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Engineers, Architects, Builders, Roofers 
and Waterproofers 













k t. 


WATERPROOFING engineering is not taught in any college, and 
the writers of engineering papers descriptive of engineering works 
only rarely embody information on waterproofing. In general, this 
branch of engineering is given far too little consideration and study 
in the laboratory and in construction. Its importance warrants 
a better acquaintance with its laws than exists among those most 
vitally interested. To remedy this condition and seemingly to 
supply a real need to the profession, I commenced, early in 1914, 
a systematic search and diligent study of existing literature on 
the subject of waterproofing. The field was large but the harvest 
surprisingly small. Secrecy is the keynote in nearly all commercial 
literature on waterproofing; but with the aid of chemistry much 
of this was dispelled. The technical literature is often but semi- 
illuminating, though some excellent papers and reports have been 
read before various engineering societies. In fact, the impression 
gained from perusing the literature extant on waterproofing was, 
that the subject seemed to be regarded as a sort of necessary evil in 
engineering, to be overcome as best as the exigency of the case would 
permit, and if this failed to try again and again until successful. 
The cost of waterproofing was often the last consideration, but 
it invariably became the least in the mad effort to successfully 
waterproof the more important structures. This attitude is funda- 
mentally and morally wrong and economically unsound, because 
we may find it expedient to justify our ignorance, but never 

In writing this book it is believed that my extensive practical 
experience and experimental research work in waterproofing engi- 
neering has qualified me to undertake this task, the magnitude of 
which has not been underestimated. Much thought and labor 
were devoted to the task of compiling and simplifying the text so 
as to make it understandable by all interested in the subject of 
waterproofing, which interest, fortunately, is gradually increasing 
among engineers, architects and contractors. 

An effort is also made to explain past and present methods and 



materials of waterproofing; investigate their efficiency; draw 
helpful, if not perfectly exact conclusions, and, where possible, 
establish standard methods and materials for general waterproofing; 
and lastly, to emphasize the value of careful study of the whole 
subject by engineers, especially those engaged in design. 

In the hope that it will engender new thought and investigation, 
and in the belief that waterproofing engineering is now coming into 
its own, this book is dedicated to the engineering profession. 

It has been found impracticable in many cases to acknowledge 
due indebtedness, for material used, to those writing in technical 
and engineering society journals on waterproofing; I herewith extend 
to all my grateful thanks. 

Most kind acknowledgment for valuable assistance and sugges- 
tions are due and gratefully given to Mr. Percy S. Palmer, C.E., 
Mr. William F. Holzschuch, C.E., Mr. Samuel G. Margies, C.E., 
Mr. Max Miller, C.E., and particularly to Mr. Raymond J. 
Reddy, who, besides contributing information gained from practical 
experience, has been of great assistance in the preparation of the 
manuscript and drawings. I also take pleasure in acknowledging 
my indebtedness to and esteem for Mr. George L. Lucas, General 
Inspector of Materials of the Public Service Commission, 1st Dist. 
of New York, in whose department the opportunity and material 
for writing this book were secured. 


November, 1918. 





Introduction 1 

Conditions Creating Necessity of Waterproofing 1 

Waterproofing The Universal Structural Bodyguard 2 

Density for Watertight Concrete 3 

Source and Location of Ground Water, and Its Effect on Concrete 5 

Waterproofing and Drainage as a Protection against Ground Water 5 

Ineffectiveness of Weep Holes in Preventing Cracks in Masonry 6 

Causes and Effects of Porosity in Concrete 7 

Effect of Freezing Water on Concrete 7 

Effect of Sewage' and Sea Water on Concrete 8 

Destructive Effect of Electrolysis on Concrete 9 

Elimination of Electrolytic Effects 10 

Effect of Temperature Changes on Concrete 11 

Effect of Expansion Joints in Masonry 12 

Effect of Uneven Settlement on Masonry 13 

Hygienic Need of Waterproofing 13 



Progress of the Art of Waterproofing 17 

Surface Coating System of Waterproofing: Definition, Purpose and 

Development 18 

Methods of Applying Surface Coatings 19 

Preparation of Masonry Surface Prior to Application of Coating 21 

Application of Slush, Scratch and Finishing Coats 22 

Materials Used for Surface Coatings 23 

Application of Cement Mixtures 23 

Use of Lean and Rich Mortars 25 

Application of Powdered Metal 27 

The Sylvester Process '. 28 

Application of Paraffin 28 

Application of Bituminous Compounds 29 

Membrane System of Waterproofing: Definition, Purpose and Development 31 

Surface Preparation Prior to Application of Membrane 33 

Necessity of Continuity of Membrane 34 

Protection of Membrane 35 




Methods of Applying Membrane Waterproofing 40 

Making Membrance Mats 42 

Connecting New and Old Membranes 42 

Placing Membranes around Projections and in Vicinity of Steam Pipes ... 43 

Use of Special Membranes 45 

Considerations for Selecting Membrane Reinforcement 46 

Storing and Unrolling Felt and Fabric 48 

Precautions when Heating Coal-tar Pitch and Asphalt 49 

Proper Use of Kettles and Fuel when Heating Pitch or Asphalt 50 

Differentiating between Coal-tar Pitch and Asphalt in the Field 51 

Coal-tar Pitch Versus Asphalt for Waterproofing 51 

Mastic System of Waterproofing: Definition, Purpose and Development. . 52 

Applying Mastic Waterproofing 53 

Precautions when Joining New and Old Brick-in-Mastic 57 

Placing Mastic around Projections and in Vicinity of Steam Pipes 57 

Preparation of Wall Surfaces for Brick-in-Mastic 58 

Precautions for Setting-up, Filling and Stripping Forms for Brick-in-Mastic 

Walls 59 

Settlement and Bracing of Brick-in-Mastic Walls 61 

Materials for Making Mastic Their Properties and Proportions 62 

Hand Versus Machine-made Mastic 63 

Brick-heating Methods 65 

Weather Conditions Governing Waterproofing Operations 66 

Integral System of Waterproofing: Definition, Purpose and Development 66 

Limitations of the Integral System of Waterproofing 68 

Integral Waterproofing Materials and Their Application 69 

Use of Hydrated Lime 69 

Use of Inert Fillers 70 

Use of Active Fillers 72 

Use of Proprietary Cements 72 

Use of Integral Liquids 74 

Use of Integral Pastes 75 

Self-densified Concrete : Definition, Purpose and Development 76 

Methods of Making Dense Concrete 77 

Scientific Proportioning 78 

Grade of Workmanship and Supervision Necessary for Watertight Concrete 81 

Grouting Process of Waterproofing: Definition, Purpose and Development 82 

Application of Grout for Waterproofing 84 

Cement and Sand for Grouting 85 

Equipment for Grouting Process 86 

Steam Pressure Concrete Mixing and Placing Machine 89 


Impervious Roofing Defined 91 

Properties and Application of Shingles 92 

Wood Shingles 92 

Slate Shingles 93 



Tile Shingles 95 

Prepared Shingles 100 

Asbestos Shingles 101 

American Method of Applying Asbestos Shingles 103 

Hexagonal and French Methods of Applying Asbestos Shingles 103 

Tin Roofing 105 

Properties and Application of Tin Roofing 105 

Felt (or Composition, or Built-up) Roofing 108 

Applying Felt Roofing 108 

Varieties of Prepared or Ready Roofings 112 

Applying Ready Roofings 114 

Roof Flashings 116 

Roof Gutters 118 

Functional Roofings 12Q 

Definition; Use and Varieties of Functional Roofings 120 



Function and Properties of Expansion Joints 124 

Monolithic Construction Obviates Expansion Joints 125 

Design .and Spacing of Expansion Joints 126 

Joints in Brick Masonry 126 

The Slip-tongue and Plane-of- Weak-Bond Joints 127 

Illustrations of Expansion Joints 128 

Cut-offs in Expansion Joints 134 

Physical-acting Expansion Joint Fillers , 140 

Chemical-acting Joint Fillers 143 


Selection and Adaptability of Materials 145 

Materials for Different Systems of Waterproofing 145 

Nature of Materials Acting Chemically as Waterproofing Agents 147 

Nature of Materials Acting Mechanically as Waterproofing Agents 153 


Applicability of Tools and Machinery for Waterproofing 166 

Varieties of Mastic Mixers 166 

Varieties of Heating Kettles 170 

Sundry Waterproofing Implements 176 

The Cement Gun 184 

The Grouting Machine 186 





Necessity of Testing Waterproofing Materials 188 

Significance and Description of Technical Tests on Bitumens 189 

Specific Gravity 190 

Flash Point 191 

Solubility in Carbon Bisulphide 192 

Solubility in Carbon Tetrachloride 194 

Solubility in Petrolic Ether 194 

Penetration Test 195 

Methods of Determining Melting-points of Bitumens 197 

Ductility Test on Bitumen 209 

Evaporation Test on Bitumen 212 

Determination of Free Carbon in Coal-tar Pitch ' . . . 214 

Ash Test 217 

Fixed Carbon Test 217 

Paraffin Test 218 

Dimethyl Sulphate Test 219 

Tests on Treated and Untreated Cement Mortar and Concrete 219 

Standard Instructions for Permeability Tests 220 

Description of Standard Apparatus 221 

Method of Testing Permeability of Waterproofed Concrete 222 

Results of Permeability Tests on Waterproofed Concrete 224 

Results of Permeability Tests on Plain Concrete 227 

Description and Results of Practical Tests 229 

Test on Absorption of Concrete 229 

Test on Concrete Floor Hardeners 231 

Comparison of Melting-points of Bitumens 235 

Effect of Heat on Various Pitches Mixed with Linseed Oil 236 

Flowing and Bonding Properties of Pitch Containing Small Quantities of 

Asphalt or Linseed Oil 238 

Effect of Asbestos Filler on the Physical Properties of Bitumen 238 

Ductility of Asphalt Containing Coal-tar Pitch 240 

Effect of Temperature on Penetration and Ductility of Asphalt and Coal- 
tar Pitch 241 

Comparative Tests on Coal-tar and Asphalt Mastics 247 

Volume Reduction of Asphalt Mastics 248 

Mastic Bond Affected by Surface Condition of Bricks 249 

Relative Compression of Plain Brick, Brick and Mortar, and Brick-in-Mastic 249 

Effect of Temperature of Saturants on Waterproofing Fabrics 251 

Relative Amount of Saturant and Coating Material on Treated Water- 
proofing Felts and Fabrics 252 

Effect of Drinking Water on Waterproofing Fabrics 254 

Effect of Ground Water on Waterproofing Fabrics 255 

Relative Absorption and Strength of Raw and Treated Waterproofing Felts 

and Fabrics 256 

Immutability Test on Various Waterproofing Felts and Fabrics 260 

Compressibility of Treated Jute-fabric Waterproofing Membranes 260 





Specification Requisites 262 

Specifications for Waterproofing-Materials 263 

Specifications for Waterproofing Concrete and Masonry Structures 273 

Specifications for Waterproofing Tunnels and Subways 280 

Specifications for Waterproofing Railroad Structures. 293 

Specifications for Waterproofing Concrete Floors 305 

Specifications for Waterproofing Roofs 306 


Origin and Nature of Special Formulas 313 

Masonry Treatments . 314' 

Treatments for Tanks 317 

Floor Treatments . 319 

Roofings 319 

Waterproof Cements 320 



Examples of Surface-coating Applications 323 

Examples of Membrane Applications 331 

Examples of Mastic Applications 353 

Examples of Integral Waterproofing Applications 356 

Examples of Self-densified Concrete Applications 356 

Examples of Grouting Applications 357 

Examples of Special Waterproofing Applications 360 



Planning and Estimating 368 

Importance of Accurate Estimates 368 

Accurate Estimates Dependent on Accurate Methods 369 

Labor and Materials - 370 

Waterproofing Labor, Contractors and Manufacturers Graded 370 

Cost Data Tables 371 


Explanation of Tables 379 

Thermometric Equivalents 380 

Specific Gravities and Degrees, Baume, for Liquids Heavier and Lighter 

than Water.. 381 



Specific Gravity and Coefficient of Expansion-of Various Materials 387 

Weight and Thickness of Burlap, Felt, and Cotton Fabric Membranes with 

Coal-tar Pitch Binder 388 

Thickness of Waterproofing Materials Required for Different W 7 ater 

Pressures 389 

Volumes and Weights of Ingredients Used in Brick-in- (Asphalt) Mastic 

Waterproofing 390 

Pressure Exerted by Water Beneath Floors and against Walls 392 

Approximate W 7 eights and Thicknesses of Various Sheet Metals for Roof, 

Gutters and Flashings 393 

Weights of Roof Coverings 395 

Square Feet Covered by 1000 Wooden Shingles 396 

Number of Slates and Pounds of Nails Required for Roofing 97 

Size, Length, Gauge and Weight of Roofing Nails 397 


Explanation of Mechanical Analysis for Grading Concrete Aggregates 399 

Concrete in Sea Water 403 

Report on Waterproofing American Society for Testing Materials 408 

Glossary of Terms Used in the Waterproofing Industry 413 

References 423 

INDEX. . 428 




THE art of waterproofing, while having passed its infancy, is 
not yet in its adult stage of development. That it has developed 
from a crude understanding and practice is evident from the fact 
that the ancient Romans would waterproof their structures by 
building foundation walls so thick that water could not possibly 
percolate through them. 

Searching through both ancient and modern annals for a his- 
tory of the subject, we are consistently confronted by the scarcity 
of reliable literature on waterproofing; but it is quite well ascer- 
tained that the early Egyptians used asphalt * to waterproof the 
foundations of the pyramids, that they waterproofed the ground 
floors of some houses by internal and external applications of bitu- 
minous material, and used it also in the construction of cisterns, 
silos, and other works where waterproofing was necessary: that the 
Romans were among the first to apply successfully the early prin- 
ciples of waterproofing and were the first successful manufacturers 
of hydraulic cement. This cement was a natural cement similar 
to our present day puzzolan cement. Of course, waterproofing 
engineering as practiced by both the Egyptians and Romans must 
be taken in a restricted sense, for the art, as now developed and as 
we comprehend it to-day, was quite unknown then. 

Conditions Creating Necessity of Water roofing. It has been 
quite definitelv proven that water is practically a universal 
solvent; i.e., given time and water, especially sub-surface water, 
very few things will resist the deteriorating effect of the latter. At 

* For earliest history of asphalt, see: " Manufacture of Varnishes and Kindred 
Industries " by Livache and Mclntosh, Vol. 2, p. 3D. 

* " *- ." 


certain distances below ground surface, varying both seasonally 
and locally, water is nearly (within several feet) at the same level 
(called ground-water level) throughout the year. All engineering 
structures, of course, have their foundations in earth or rock (which 
is the same thing so far as water pressure is concerned) and may be 
partly or entirely submerged by ground water; consequently they 
are subject to considerable water pressure and to the disintegrating 
influences of the acids or alkalies usually present in ground water. 
It is also evident that due to uneven settlement and continual 
variations of temperature, cracks may develop in superstructural 
and subsurface masonry, foundation walls, etc., through which water 
will seep regardless of how minute these cracks may be; hence 
waterproofing in some form becomes essential to the life and sta- 
bility of the structure. What this form of waterproofing should be 
is a problem not susceptible to precise mathematical solution, but 
by a careful study of conditions and with the help of past and present 
experience, and a knowledge of the chemical and physical properties 
of waterproofing materials, a form or method can be devised suitable 
for any special condition. Therefore, a knowledge of all manner of 
waterproofing systems and the properties of suitable materials 
becomes indispensable, at least to the engineer and architect, who 
usually specify how and what should be used under given conditions 
or for particular structures. 

Waterproofing The Universal Structural Bodyguard. Our era 
has rightly been designated the " Concrete Age." In fact, the 
growth of our civilization might be measured by the quantity produc- 
tion of cement, and the commercial progress of a community might 
be measured by the number and size of the concrete structures 
within its boundaries. In the not distant past, most solid struc- 
tures were composed of ordinary brick or stone masonry, and to-day 
not a few are similarly constructed, but these are rapidly being super- 
seded by concrete and steel. Even for dwellings concrete is becoming 
more adaptable and is being used more every day, and the prediction 
is made that the future will see a predominance of concrete buildings 
of all varieties. 

But co-ordinately with the use of concrete, or nearly so, is the 
provision of a " body guard " in the form of waterproofing. For, 
as iron and steel must be protected from corrosion, so must concrete 
be protected from disintegration, but unlike the former, concrete 
must also be made impermeable. Water, by its capacity of alternate 
freezing and thawing, reacting upon concrete as ordinarily made, 
with its inherent porosity, wherein water may lodge and exert its 


expansive or disintegrating forces, is the bane of such structures. 
On the other hand, water pressure is an added bane of subsurface 
structures. All of these causes and their effects preclude the possi- 
bility of making a permanently element-resisting structure without 
some form of protection. Waterproofing affords this protection. 
Efficient waterproofing is therefore rightly co-ordinate with concrete, 
the universal structural material, and the materials used to accom- 
plish this should therefore be classed as structural materials. Water- 
proofing not only protects but prolongs the life of any structure 
to which it has been properly applied. Proper waterproofing 
materials intelligently and adequately applied is the keynote of 
success in making all engineering structures watertight. But even 
appropriate materials unsystematically applied, or vice versa, will 
not produce a waterproof medium. This emphasizes the necessity 
of knowing all the related factors in waterproofing a structure as 
well as in designing it. 

Density for Watertight Concrete. In the making of concrete it 
is attempted to duplicate natural stone, in form, design and color, 
but especially in density. The density of average concrete is more 
nearly equal to that of the lighter stones (see Table I), though in 
practice the effort is universal to make it approach that of the heavier 
ones, which effort has the desirable effect of reducing its porosity. 
To accomplish this, engineers often and rightly resort to scientific 
proportioning of the aggregates, increased time of mixing, careful 
tamping, spading and closer supervision of construction, or again, 
by incorporating certain water-repellent or void-filling ingredients 
in mass concrete or in the mortar used for laying up the stone 
masonry. Where these precautions are impossible or inadequate, 
the structure may be placed in or surrounded with an impervious 
bituminous sheet-layer or membrane, forming an external water- 
proofing medium. 

From Table I it is evident that not only concrete but all kinds 
of stone are more or less porous. Hence this property, being inherent 
in all stones, must not be overlooked in construction work where 
it may cause damage. But this is especially true of concrete, 
because, as is obvious from the table, it is very difficult to make 
ordinary concrete denser than average limestone, and consequently, 
its porosity being always present, is more menacing to the integrity 
of any concrete structure. 

Ordinary concrete will absorb water more readily than is generally 
supposed. The presence of alkaline, such as magnesium or sodium 
sulphate, or of acid in ground water, tends to attack the cement in 


some manner not yet definitely known, and is one of the chief causes 
for the disintegration of concrete. This is especially true of the 
action of sea water on concrete. Other causes tending to disintegrate, 
or in some manner to disrupt concrete, are electrolysis, temperature 
changes and uneven settlement. A brief review will be made of each 
of these causes and their effects. 



Kind of Stone. 

Lb. per 
Cu. Ft. 


Lb. per Cu. Ft. 



2 92 

Max. Min. 
1 03 23 



2 72 

1 04 10 

Slate . . 


2 70 

2 10 05 



2 70 

2 77 04 



2 60 

6 62 02 



2 60 

3 71 60 



2 40 

11 60 02 




18 . 75 



2 65 



1 50 


Kind of Aggregate. 

Lb. per 
Cu. Ft. 


Lb per Cu. Ft.* t 



2 48 




2 40 











2 30 

2 48 



2 29 



1 79 

9 61 

* For exact method of determining absorption of water per cubic foot of rock, see 
American Society of Civil Engineers Transactions, Vol. 82, p. 1437 (1918). 

t The figures in the last column were estimated from tests made on 6-inch cubes of 1 : 2 : 4 




Since water is the all-important cause creating the necessity for 
waterproofing, we will consider briefly its source and general loca- 
tion in the ground. 

Ground water is that part of rain, hail or snow that has percolated 
through and accumulated in the ground as water, either in soil or 
in rock, usually in consequence of an underlying impervious stratum 
which materially retards or totally prevents its further percolation 
downward. The upper surface of ground water is called the water 
table, or the ground-water level. The depth of ground-water level 
below the earth's surface varies with the locality, topography and 
character of the earth's material.* Ground-water level has nothing 
to do with mean high water, though in some localities they are at 
the same elevation; the latter surface, however, is usually lower. 
Proper drainage will, of course, lower ground-water level, and this 
is often resorted to in order to obviate the need of more extensive 
waterproofing. But as the limit of this level is mean high-water 
level, its successful possibilities are not unlimited. So far as water- 
proofing is concerned, therefore, the two water levels require equal 
consideration, because one or the other, or both, are always operative. 
A clause in the specifications for waterproofing the new subways 
in New York reads: " waterproofing cf the structure will be limited 
to the roof and to those surfaces near ground water, or mean high 
water, if ground-water level is found for any reason to be below mean 
high water." Flood water is less difficult to control than either 
sea or ground water, and only affects certain localities at certain 
times, often due to accident. Its effects are readily overcome by 
proper drainage, damming or simple waterproofing methods. 

Waterproofing and Drainage as a Protection against Ground 
Water. The most general effect of ground water on engineering 
works is to necessitate these works being constructed with special 
waterproofing considerations. The earth below ground-water level 
remains wet constantly, often subjecting an underground structure 
to a large hydrostatic head. It is this head of water which requires 
careful attention and design to make it effective. And what can- 
not be accomplished by design -alone can be accomplished by inclu- 
ding a system of waterproofing to prevent the percolation of water 
through the more or less porous concrete, or through slight cracks 
that may develop in it. 

* Turneaure and Russell, " Public Water Supply." 


An underground system of drainage is often included even where 
a complete system of waterproofing is called for and provided, as in 
the above cited subway specification, to wit: "Every part of the 
railroad must, so far as possible, be so arranged that any water 
finding access thereto will be led away automatically to the city 
sewers. Where the railroad is on an inclined gradient, and is con- 
structed in dry, porous soil, the floor of the railroad may be depended 
on to act as a conduit. At the bottom of the inclined gradient 
connection must be made with a sewer or with subdrains lying 
beneath the railroad and draining into the sewers. 

" Along such parts of the work where the soil is not porous, or 
where the floor of the railroad cannot, in the judgment of the engineer, 
be used as a conduit there shall be laid, beneath the rail level and on a 
continuous descending gradient, drain pipes of vitrified tile. Each 
drain shall be laid in the concrete or directly in the soil with tight 
or open joints, as directed, and in such manner and in such position 
as, in the opinion of the engineer, local circumstances require." 

Ineffectiveness of Weep Holes in Preventing Cracks in Masonry. 
Concrete retaining walls and abutments, but more especially the 
former, are, as a rule, provided with weep holes to take care of the 
water at their backings. The practice adhered to is to let one weep 
hole 3 or 4 inches in diameter suffice for every 3 or 4 yards of wall 
front. But experience has demonstrated that such weep holes 
do not always suffice to protect a wall against water pressure (in 
so far as it affects percolation), still less against deteriorating agencies 
in the water, and least of all do they prevent surface disfiguration 
due to efflorescence. Neither do weep holes prevent subsequent 
and uneven settlement with consequent cracking of the masonry. 
The reason is quite obvious; for weep holes too often and too easily 
become clogged, and are in consequence unable to carry off the 
storm water rapidly, which is their main function, consequently the 
water accumulates in the backfill and backs up behind the wall, 
causing, with the aid of head and frost, the damages referred to 

While waterproofing would not overcome all of these defects, 
it would undoubtedly eliminate to a marked degree their effects. 
In fact, the tendency in present-day construction is to eliminate 
weep holes and substitute a type of waterproofing meeting the 
purpose and need of the structure. Thus it is seen that ground 
water is the elemental cause against which concrete structures must 
be protected by the application of some waterproofing material or 
drainage system, or both. 



Cement mortar and concrete, even when made under laboratory 
conditions, are far from being dense enough to completely pre- 
vent the percolation (independent of absorption) of water through 
them if time is reckoned as a factor. The volume of total voids 
in mortars averages about 26 per cent, and in concrete, of pro- 
portions commonly employed in practice, the voids range from 
13 to 17 per cent. That this is a common as well as a serious 
condition follows from the fact that many laboratory tests show 
that 70 to 80 per cent of the tempering water evaporates, 
leaving behind it the cells that it formerly occupied, and as these 
cells are more or less connected, a system of ducts through the 
entire structure is established. This cellular condition creates 
a natural capillary passageway for water to enter and be absorbed 
in the mass. But the permeability of mortar or concrete is 
practically independent of that form of porosity wherein the voids 
form an unconnected system , but the freezing effect is quite different, 
and is referred to below. 

At this point it is probably well to remind the reader not to 
confound porosity with either permeability or absorption, for con- 
crete may be porous and yet absorb little water, and it may be 
absorptive, and yet not permeable. 

Porosity of concrete may be defined as the net-work of uncon- 
nected voids or honeycombing of its mass by the entrained air and 

Absorption of concrete is the property of drawing in or engrossing 
water into its pores or voids by capillary action or otherwise. 

Permeability (or percolation) of concrete may be defined as that 
quality, due to cracks or connected voids, which permits the flow of a 
liquid through it. 

Effect of Freezing Water on Concrete. All three states, that is 
porosity, permeability and absorption, are allied, and each one in 
some way is detrimental to concrete, for, whether water is entrained 
in the mass * or flows through it, or is absorbed by the concrete, 
when it freezes some form of damage is done. There are but few 
bonds strong enough to resist the expansive force of freezing water. 
It increases its bulk approximately 10 per cent, and the consequent 
expansive force is probably more than 10,000 pounds per square inch. 
A section of concrete 100 feet long, under 100 deg. Fahr. (55.5 deg. 
Cent.) change in temperature, will contract or expand T % 6 ^ of an 
* See striking example in Engineering News, Vol. 77, No. 9, p. 356. 


inch. This change is infinitesimal in comparison to the volumetric 
change in freezing water; hence the need for eliminating the porosity 
of concrete and also preventing the percolation of water through it. 
For evidence of the effect of the expansive force of freezing water, 
one need but observe the physical condition of natural stones exposed 
to the elements for a more or less protracted period of time. Even 
mountains, with their proverbial strength, are crippled by this agency. 
A very striking example of the effect of this tremendous mechanical 
force is seen in the crumbling of the exposed portions of the rocky 
Palisades on the New Jersey shore of the Hudson River. 

Effect of Sewage and Sea Water on Concrete.* That the dura- 
bility of concrete is materially impaired by its porosity is strikingly 
illustrated by the easy prey it falls to the action of alkali waters, 
sewage and sea water. 

The alkalies contained or formed by or in these waters, which 
are most active in causing disintegration of concrete, especially 
when allowed to penetrate into the interior of the mass, are the 
sulphates of sodium, magnesium, and calcium. 

Disintegration of concrete in sewers and sewage disposal works, 
whether due to the use of poor materials, poor workmanship, or lean 
mixtures, each of which tends to decrease the density of concrete, 
has been found to take place above the normal surface of the liquid 
contained. This action probably results from the fact that quanti- 
ties of hydrogen sulphide are evolved from the sewage. This sul- 
phide is produced in two ways: (a) By the bacterial decomposition 
of sulphur-containing proteins and related compounds, and (6) the 
reduction of sulphates which are contained in unusual amounts in 
some water supplies. Of the two, the second seems to be more 
important. The hydrogen sulphide which escapes as gas from the 
sewage is partially dissolved in the moisture on the under side of the 
roof and concrete walls. Here it is oxidized to sulphuric acid partly 
by atmospheric oxidation and partly by bacterial action. The 
sulphuric acid acts upon the calcium compounds in the concrete, 
forming calcium sulphate, thus breaking down the concrete. 

Where the effect of sea water on concrete has been other than 
mechanical, it is probable that disintegration is caused by the sub- 
stitution of magnesium oxide (MgO) from the sea water in the place 
of the calcium oxide (CaO) of the cement, as well as to the decrease 
in the proportion of silica and the increase in sulphuric anhydride 
(SOs). Interesting examples of these processes will be found in 
Engineering and Contracting, Vol. 57, No. 26, p. 580. The United 
States Bureau of Standards, after some extensive tests on the " action 
* American Railway Engineering Association, Vol. 14, p. 834. 


of the salts in alkali water and sea water on cements," described in 
Technologic Paper No. 12 of the Bureau, remarks as follows: 

" The cause of the disintegration of cement structures is not 
certain, though it is almost universally believed that it is the reaction 
of sulphate of magnesia of the sea water with the lime and the 
alumina of the cement, resulting in the formation of hydrated 
magnesia and calcium sulpho-aluminate, which crystallizes with a 
large number of molecules of water. Other constituents of sea 
water, especially sodium chloride and magnesium chloride, have also 
been noticed to attack the silicates of the cement and produce rapid 

To safeguard concrete structures against the destructive action 
of the above agents, it is necessary to make dense, impermeable 
concrete by the use of a well-graded aggregate, moderately rich 
mixture, proper consistency and good workmanship, and allowing 
the concrete to harden under favorable conditions before being 
exposed; or, where practicable, by applying a surface mortar coat 
from 1 to 2 inches thick. Both of these methods are included in 
distinct systems of waterproofing, which are explained in Chapter II. 
In Appendix II will be found more explanatory information on this 
interesting phenomenon. For experimental confirmation the reader 
is referred to the above Technologic Paper. 


In the principle of electrolysis we have a very formidable 
agent at work against the integrity of concrete structures; one 
that requires careful study and attention in structural design 
and during construction. Its effect is mechanical and, though 
not widespread, is as disastrous as the freezing of water in 
concrete. The passage of an electric current through reinforced 
concrete causes, amongst other effects, oxidation of the iron rein- 
forcement. The oxides formed occupy 2.2 times as great a volume 
as the original iron and the pressure resulting from this increase 
of volume is very great. That it is possible to damage re- 
inforced concrete structures by stray currents from electric 
railways, power-houses, and general ground connections is an 
established fact.* Electric currents passing from the reinforcing 
material into the concrete for electrolytic action takes place only 
where the current leaves the conductor cause corrosion of the 
reinforcement and cracking of the surrounding concrete more or 
less seriously, but always sufficiently to permit the percolation of 
water through it, which further aids electrolysis; this, in turn, 
* Technologic Paper No. 18 of the Bureau of Standards, U. S. A. 



creates more cracks, thus permitting more water to enter and attack 
the reinforcement, whence the action is further enlarged until there 
arises serious danger that rupture may ensue.* 

Elimination of Electrolytic Effects. Partial elimination of elec- 
trolysis is possible by the selection of courses of masonry or con- 
crete of a high specific resistance and their careful distribution about 
the structure. As an illustration: If blocks of granite are inter- 
posed between the footings of a building and the soil, the tendency 
of the building to pick up stray currents is materially reduced because 
of the high electrical resistance of the granite. It may be impractic- 
able to take these precautions, but it is nearly always possible to 
surround the footings with a waterproofing membrane which will 
accomplish the desired end. See Fig. 1. 

Various proportioned concrete aggregates offer greater or less 
resistance to electrolysis with a showing in favor of what would 
ordinarily be called a poor concrete. 

Table II f shows the specific resistance of concrete made of Old 
Dominion cement, river sand and crushed trap. The specific resist- 
ance of concrete will, of course, vary greatly with the aggregate, 
method of making, etc., and the values given below are indicative 
only of the order of magnitude of the specific resistance that may be 


of Mortar. 

in Ohms cm. 3 

of Concrete. 

in Ohms cm. 3 

Neat cement 


1 :2! :4 


1 :2 


1:3 : 5 


1 :4 




In general, complete protection from electrolytic effects is not 
practically possible by any other means than efficient waterproofing. 
What form of waterproofing should be used for this, purpose depends 
on local conditions and the type of structure, but invariably that 
system which is of a membraneous nature will be most efficient. 
Precautionary measures against electrolysis must be taken both 
in the city and in the country, but perhaps more so in the country 
because electrical feeders are usually much better protected in cities, 
where laws are enacted for this purpose. 

* Engineering News, Vol. 66, June 8, August 3 and 17, 1911; Vol. 68, July 12, 
December 19, 1912. 

t Technologic Paper No. 18 of the Bureau of Standards, U. S. A. 




A fourth disrupting force, and one not easily overcome, is 
change of atmospheric temperature, to which influence can be 
ascribed many concrete failures. Additional steel embedded near 




C.I. Manhole Cover. 

8 Brick- 
Waterproofing Membrane- 

4 "Brick Protection- 
Hollow Tile Protection 

FIG. 1. Methods of Waterproofing around Column Bases and Footings to 

Prevent Electrolysis. 

the surface of the concrete is one of the means employed to combat 
this force. The effect of the temperature change, however, is 
never wholly lost, especially, though rarely, where concrete is 
depended upon to take tensile stress. Just to illustrate: Assuming 


the coefficient of expansion of concrete as .0000055 per deg. Fahr., 
and its modulus of elasticity as 2,000,000 pounds per square inch, 
then the stress due to temperature is 11 pounds per square inch per 
degree change of temperature, or, for 60 deg. Fahr. it is 660 pounds 
per square inch, which is double the ultimate unit tensile stress for 
concrete. A temperature difference between summer and winter of 
twice 60 deg. Fahr. is not uncommon in certain parts of the United 
States.* Fortunately, in this country, tensile strength of concrete 
is neglected. It must not be supposed, however, that steel rein- 
forcement, however efficiently placed, does more than diminish 
the size and distribute the cracks which are caused by temperature 
changes. But this result is sufficient to materially increase the 
impermeability of the structure. 

Effect cf Expansion Joints in Masonry. In steel, a change of 
temperature of 1 deg. Fahr. causes a stress of about 200 pounds per 
square inch if resisted. In concrete a change of 18 deg. Fahr. causes 
an equal stress if likewise resisted; that is, if expansion joints are 
not provided to take care of the expansion and contraction, the 
resulting stresses may cause cracks in the structure, with the usual 
result cf disfigurement due to efflorescence and damage due to seepage. 
But, on the other hand, these very expansion joints create one of the 
most urgent needs for waterproofing a concrete, or for that matter, 
any form of masonry structure. 

Expansion and contraction in a structure and their resulting 
stresses are due to changes in atmospheric temperature or change 
in temperature of the concrete while it is setting and hardening. 
This latter temperature change may be as high as 150 deg. Fahr., 
depending on the thickness of the masonry, f With steel rein- 
forcement to take care of stresses resulting from temperature 
change, the cracks are kept small, but not entirely prevented. The 
expansion joints necessary to relieve the atmospheric Jbemperature- 
change-stresses require special study. Their form and location in a 
structure not only have a great bearing on the stresses set up in it but 
also on their effectiveness. While expansion joints tend to relieve the 
effects of these stresses, they are not always effective in preventing 
hair cracks or cracks at angles in the structure, or leakage through 
the joints themselves as commonly constructed. Hence the need of 
an efficient type of waterproofing, in conjunction with well-designed 
expansion joints, > which together will most effectively overcome 
these defects. 

* American Civil Engineers' Pocket Book, 2d Edition, p. 1255. 

t Taylor and Thompson, "Concrete, Plain and Reinforced," 2d Edition, p. 285. 



A fifth important destroying agency to consider in concrete con- 
struction is uneven settlement. An inequality of bearing power will 
cause uneven settlement in a structure. Only the most careful de- 
signer can minimize and perhaps eliminate settlement, which some- 
times causes unsightly cracks, and, of course, reduces the imperme- 
ability of the structure. Retaining walls are particularly subject 
to stresses of this character. Bridge abutments and building foun- 
dations sometimes suffer a good deal from this cause. When to this 
is added the vibration in each, due to traffic or the operation of 
machinery, the injuries are enhanced in a manner that invites further 
damage when water enters the cracks. 

Where masonry walls support backfill behind them and tracks 
above them, settlement may occur due to pounding of trains on 
the tracks. Or, if drainage behind the walls is, or becomes, inade- 
quate for any unforeseen reason (due to clogging of weep holes, for 
instance), the earth, underneath the foundation may be undermined, 
causing more or less settlement with consequent cracking and the 
percolation of water. Concrete reservoirs often develop cracks 
from this cause, and in spite of their eventual silting-up often con- 
tinue to be troublesome until properly waterproofed. In fact, it most 
generally happens that settlement cracks are too large to be closed 
up by silting, or there may be no silt to depend on, as when building 
in rocky strata. But even where silt is abundant and is depended 
upon to close up any cracks, it always takes time, invariably defaces 
the structure, and the cracks may reopen by further settlement. 
Consequently, nothing remains to be done but to waterproof the 
structure, in a manner that will minimize or vitiate the effects of 
this agent. 

Hygienic Need of Waterproofing. The above considerations 
undoubtedly establish the fact that the ill effects of the inherent 
porosity of concrete and the perviousness of general masonry should 
be eliminated as far as possible as a matter of economy and safety. 
And, incidentally with the exclusion or repulsion of water (which 
action depends on the system of waterproofing employed) from a 
concrete structure, that is, with a dampproof and waterproof 
condition of a structure, follow other results and benefits that have 
both an aesthetic and hygienic effect which can ill afford to be over- 
looked. Concrete construction which proceeds with the idea of 
permanency should embody the co-ordinate functions of damp- 
proofness and waterproofness and uniform surfaces, free from 







unsightly blotches and discoloration by efflorescence. (See Fig. 2.) 
The latter defect in concrete and brick masonry is mainly due to the 
absorption of atmospheric moisture, which dissolves the salts of soda, 
potash, magnesia, etc., present in the cement and, on evaporating, 
deposits them on the surface. But in many instances rain or 
ground water from behind walls or other structures percolates 
through the mortar or expansion joints, day's-work planes, cracks, 
or through the very body of the masonry, carrying with it also various 
oxides which leave rusty looking streaks or white and yellow patches 
on the face of the masonry that often makes an eyesore of an othei- 

FIG. 3. Evidence of Exudation of Lime Salts through Wall Unprotected by 
Waterproofing or Dampproofing. 

wise beautiful engineering structure. (See Fig. 3.) This condition 
is true of masonry both above and below ground, although in the 
latter case it is usually neglected. Where only this condition is 
to be prevented, the incorporation of a bona-fide integral compound 
is the most efficient means of accomplishing the desired end. Where, 
however, cracks are inevitable, only a membraneous system of 
waterproofing can. overcome this defect. 

In building construction, the absorption and retention of moisture 
in walls above ground, and moisture and water in cellar and founda- 
tion walls and floors below ground, cause dampness which is harm- 


ful to health. Hence dampproofing, particularly in exposed build- 
ings, assumes grave importance, and further emphasizes the n3ed of 
waterproofing, because this always acts as an effective dampproofing; 
that is, any structure that has been waterproofed has necessarily 
been dampproofed. There are conditions, however, where damp- 
proofing alone is necessary or possible, as for instance, exposed walls 
of buildings. These are usually and successfully coated with a bitu- 
minous compound or covered with a thin (J inch to J inch) layer 
of plaster or cement mortar. Sometimes a waterproofed cement 
mortar coat is applied an inch or less in thickness for this purpose, 
and if the work is carefully done so that no separating plane is left 
or peeling follows, proves an efficient dampproofing medium. 

From the foregoing it may be concluded that waterproofing 
requires as careful consideration in engineering work as fireproofing 
does in building work. With so many deleterious agents constantly 
at work, not only on concrete but on all masonry, the imperative 
need of protecting all manner of structures against them, or against 
their effects, becomes apparent. The form of this protection is 
known by the broad name of waterproofing, and the art of applying 
it as waterproofing engineering. To dampproof is to make a struc- 
ture impervious to moisture. To waterproof is to render a structure 
impervious to moisture and water. To accomplish this is to preserve 
and lengthen the life of a structure, and this in turn tends towards 
economy, which is an equally important consideration to the archi- 
tect or engineer in design and construction as to the builder or owner 
of a structure. 


Progress of the Art of Waterproofing. The progress that the art of 
waterproofing has made since it began to receive serious consideration 
Is quite notable. It is difficult to affix any definite date to the adop- 
tion of scientific waterproofing, but even as late as 1870 waterproofing 
engineering, in the broad sense we are now considering it, was more 
speculative than experimental. About this time the " Sylvester 
Process " of waterproofing (originated in England) came into vogur 
among American engineers, and while it still is sometimes employed, 
it has, in the main, been superseded by better methods and materials. 
Not that asphalt 'was unused prior to this date for waterproofing 
purposes, but there seems to have been no certainty of results con- 
nected with its use. 

Since this period and up to comparatively recent times there were 
developed four distinct systems of waterproofing, namely, " Mem- 
brane," " Mastic/ 7 " Surface Coating," and " Integral." In the 
last decade, a fifth system one that will often obviate the need 
of any of the first four has received wide experimentation with 
very good and consistent results. This system is applicable only to 
concrete structures and is designated " Self-densified Concrete." 
Another recent system of waterproofing is known as the " Grouting 
Process," which is especially applicable to subsurface structures 
such as tunnels and cutoff walls either in rock or earth. Both of 
these systems will be considered in due order. 

The modern systems of waterproofing then, if arranged in the 
order of their development, appear to be as follows: 

(1) " Surface coating." (4) " Integral." f 

(2) "Membrane."* (5) " Self-densified concrete." 

(3) "Mastic." (6) " Grouting process." 

* Mr. E. W. DeKnight claims to have introduced this term in 1902; but 
this term as applied to waterproofing has only been used extensively in the last 

t This term as applied to waterproofing was used as far back as 1875 but not 
extensively until the last decade. 




Definition, Purpose and Development. The surface coating 
system of waterproofing refers to the application of: (1) In imper- 
vious coating of plastic or liquid bituminous materials; (2) various 
liquid hydrocarbons, and chemical salt solutions forming, usually, 
water-insoluble compounds; (3) a wash or plaster coat of neat 
cement or cement mortar, the former varying in thickness from 
-2 inch to -2 inch, used principally on brick walls, and the latter 
from \ inch to 2 inches; both applied either to an interior or 
exterior surface of concrete or other masonry. The cement 
mortar coating, again, may be composed of: (a) cement, sand 
and water mixed in any efficient proportion that will produce 
a dense and impervious coating; (6) cement, sand, water and a pow- 
der, paste or liquid waterproofing compound (usually of a proprietary 
nature) which is mixed in specified proportions for the purpose of 
producing similar or more impervious coatings. 

The surface coating system of waterproofing is adapted to water- 
proof structures either during construction or after erection. It is 
applicable either to the external or internal surfaces of the structure, 
depending on the physical condition of the surface to receive the 
waterproof coating, the water pressure behind the surface, the kind 
of material used and the thickness of the coating to be applied. This 
method is comparatively cheap and has a wide application in spite 
of the few materials (other than proprietary ones) adapted for such 

Amongst the oldest preserving processes in construction work 
are plastering and painting. Since paint forms an impervious coat- 
ing easily and cheaply applied, it was utilized not only for decorative, 
but also for dampproofing purposes. It was a matter of general 
knowledge that linseed oil paints and varnishes, besides serving 
other obvious purposes, were also a dampproofing medium; that 
lime plaster and cement mortar, especially the latter, applied in 
comparatively thin coats, performed the same function. Hence the 
next step in the development of this system of waterproofing was to 
apply a coat of bituminous paint or a mortar coat, thick and dense 
enough for each material to act also as waterproofing. Eventually 
there came into use proprietary waterproofing compounds employed 
directly as surface coatings or incorporated in the plaster or mortar 
coat to increase its imperviousness. 

The surface coating system of waterproofing is in common prac- 
tice to-day, especially the mortar surface coat, because with it the 



engineer encounters the least difficulties. The invention of the 
" cement gun " has made this possible more so than any improvement 
in the grading or proportioning of the ingredients for producing 
impervious mortar. The history of this invention is rather inter- 
esting. About 1895 Mr. C. F. Akeley, a taxidermist of Chicago, 
invented the cement gun for the special purpose of coating the 
framework of a dilapitated house with morta^ to save it from de- 
struction. This proved so successful that he coated other frame 
buildings by the same means. In 1911 engineers in the United 
States service in the Philippines experimented with a similar machine 
until they perfected it, and then used it quite extensively. Since 
then the cement gun has come in modified and improved form, 
into quite general use. 

FIG. 4. Applying Plaster Coat Over Bituminous Dampproofing Coat. 

Methods of Applying Surface Coatings. There are three com- 
mon methods of applying impervious coatings: (1) by brush, (2) 
by trowel, (3) by machine. All liquid compounds are applied with 
a brush (see Fig. 4) , or paint-spraying machine, both processes being 
done in the same manner that paints are applied. When thus applied, 
the compound either forms a film on the surface or penetrates the 
surface of the mortar or concrete, and by capillary action is drawn 
further in to a depth varying between J and J inch (see Fig. 5), 
depending on the solvent, porosity of the surface and density of the 
mortar or concrete. As a plaster coat, the given waterproofing 
material is applied with a trowel by hand (see Fig. 4) . In this proc- 
ess pressure and uniform motion are essential, but most essential 
is the continuity of the coating. As a mortar coat it may be applied 



either with a trowel or with the cement gun. When the plaster, 
neat cement, or mortar surface coatings are applied with a trowel, 
as on the back of a retaining wall, the outside of a brick sewer or 
manhole, the inner face of a tunnel or swimming pool, they should 
be finished off to bear a smooth or granolithic face. The granolithic 
surface on these coatings, produced only by careful troweling, 
materially increases their imperviousness. The coatings should 
not be made too thin, as peeling, blistering, and cracking inevitably 
follow, especially if used where they are subject to atmospheric 

When mortar is applied with the cement gun, the coat can be 
made a very efficient waterproofing medium, provided the materials 
are properly used and proportioned. In no case should a leaner 
mixture than 1 : 3 be used and the best results will follow the use of 

FIG. 5. Ideal Penetration of Surface Coating. 

a clean, somewhat moist and coarse, but graded sand in the mixture. 
In operating the cement gun (see Fig. 6) the dry materials are forced 
through a hose by means of compressed air, hydrated at the nozzle, 
and applied with any desired velocity. This velocity of approach 
of the mixture produces a considerable rebound of the sand, which 
is wasted; this leaves, however, the adhering mixture richer in 
cement. The combination of cement, sand and water which pro- 
duces the plastic material, takes place in transit, i.e., the hydra tion 
takes place immediately before and during the placement; the 
chemical combination or initial set of the cement takes place in its 
final resting place. If the surface is floated immediately after placing, 
a smoother finish is obtained. Troweling, however, will not always 
increase the imperviousness of the mortar, and may even offset the 
good effects of floating, hence it should be practiced with great care 
or not at all. The technique of cement-gun applications requires 
thorough familiarity with the machine and proportioning of aggregate 


before any important waterproofing work can be prosecuted success- 
fully. Chapter VI contains a more detailed description of the 
modern cement gun. 

Preparation of Masonry Surface Prior to Application of Coating. 
Before applying any of the dampproof or waterproof coatings, all 
masonry surfaces should be prepared by chipping off all skins of 
dried or hardened cement or other material, so that practically an 
entirely new surface is produced. It is best to do this not more 
than a few days prior to the application of the coatings. Chipping 

FIG. 6. Applying Mortar Coat with Cement Gun. (Operated with Power 
from Automobile Engine.) 

the surfaces will be facilitated and a much better bond secured by a 
previous application of muriatic acid of about 1 to 10 solution, the 
strength of the solution depending on the age of the structure to 
be treated. The acid should remain on the surface until it has 
exhausted itself. This will require about fifteen minutes. Then 
a second coat, and if necessary a third coat of acid solution should 
follow the first and be brushed in with a stiff wire brush. When 
sufficient aggregate has been exposed and the entire surface cleaned, 
all traces of the acid must be removed. This is best accomplished 
by a rigid application of water from a hose immediately after the 


acid treatment has reached a satisfactory stage. This slushing, 
which should be done with perfectly clean water, should continue 
until all the salts (formed by the chemical action of the acid on the 
cement) are removed and the surface is free from acid. All holes, 
large or small, should be plastered up independently of the surface 
coating unless the coating is a waterproofed mortar. 

Application of Slush, Scratch, and Finishing Coats. If the wall 
or other surface is not washed with acid it should at least be chipped 
and brushed, and just before the mortar coating is to be applied, 
the surface should be thoroughly drenched and soaked to its full 
absorbing capacity. Then, before the walls or other surfaces show 
marked signs of drying, a " slush coating " should be applied over 
the entire surface. To prepare this slush coat some of the mixed 
ready-for-use coating material may be thinned with water to the 
consistency of cream. It is then applied with a stiff brush, with a 
scouring effect, care being exercised to fully cover the inner surfaces 
of all crevices and holes. 

Before the slush coating has dried, the first application of the 
regularly mixed coating material should be applied as a scratch coat, 
from J to J inch thick, and pressure brought on the trowel to push 
the coating on, and so obtain a uniformly thick layer, well bonded. 
The best practice is to trowel the scratch coat to a fairly good sur- 
face, and then to scratch criss-cross over the entire surface before it 
hardens. This insures a better bond for the finishing coat. 

Upon the scratch coat, and before its final setting, a finishing 
coat of sufficient thickness to obtain the required thickness of mortar 
coat should then be applied. If this required thickness is more than 
1J inches, the thickness of the scratch coat should be increased 
accordingly. The finishing coat, too, should be pushed on hard and 
uniformly troweled and floated to a true surface, free from pits, 
pin holes, sagging cracks, projections or other defects. The floating 
of the finished surface is best done from the bottom of the wall up. 
These instructions are applicable whether the coating contains a 
waterproofing compound or not. 

In general, also, the surface of masonry to be waterproofed by 
the surface coating system of waterproofing should be cleared of 
any interference from timbers and temporary struts, because the 
presence of such false timbering interferes with the proper and con- 
tinuous application of the waterproofing. If such false timbering 
is not readily removable, then the locations of struts and posts, etc., 
resting on or against the surface to be waterproofed, require very 
careful workmanship and close inspection to insure the proper and 


Complete waterproofing of holes left by removal or shifting of such 
false work on the completion of the construction in hand. This 
is especially true when such timbering is situated in poorly illumined 
and cramped areas. A method of overcoming these difficulties is 
explained in the article on the membrane system of waterproofing. 
Other means of procuring a continuous surface so as to avoid leaving 
unwaterproofed areas will suggest themselves as the occasion arises; 
the important point to remember is that every temporarily unsur- 
faced spot constitutes a weakness in the waterproofing system. 

Materials Used for Surface Coatings. The materials generally 
used for surface coatings are: (1) neat cement, cement mortar, 
and proprietary cements, i.e., ordinary cements containing void- 
filling or water repelling substances; (2) finely powdered metals, as, 
for instance, powdered pig iron; (3) mixtures of soap and alum; 
(4) paraffin, either in liquid form, or in solid form, but melted, or in 
solution with petroleum oil or coal-tar naphtha; (5) patented bitu- 
minous products, i.e., mixtures of asphalt, linseed oil or wood oil 
and resin with some form of inert filler, as powdered or shredded 
asbestos; (6) proprietary liquid hydrocarbons, i.e., solutions of 
paraffin in benzine or benzol, or emulsions of petroleum oil and fat 
oil. Some of these can be applied to a wet or submerged surface 
(varieties of the patented bituminous products), but a dry surface is 
always preferable. The general properties of some of these materials 
are treated in Chapter V. 

Practical but simple illustrations of the manner and method by 
which coatings are applied are shown in Figs. 4, 7, 8. Fig. 4 shows 
a brick wall below ground surface, coated with a liquid bituminous 
paint which in turn is surfaced with a treated (i.e., waterproofed) 
mortar. This process is most effective as a dampproofing rather 
than as a waterproofing. Fig. 7 shows a culvert arch waterproofed 
with a plastic, bituminous compound. Fig. 8 is a cross-section of a 
swimming pool waterproofed with a cement mortar coating. To 
this mortar was added a definite amount of a proprietary powdered 
metallic compound to increase its imperviousness. 

Application of Cement Mixtures. In applying either neat cement 
or cement mortar, the engineer is not handicapped by lack of knowl- 
edge of the materials or results. The required information is readily 
obtainable with considerable certainty. However, when patented 
cements are used this is not true to the same degree. Experiments 
and experience have proven the waterproofing qualities of the former, 
but the same cannot be said of the latter. In fact, in many instances 
ordinary well-made and applied mortar will be more effective. 



The United States Army engineers recommend the use of sand- 
cement for mortar coatings.* This cement is sometimes substituted 
for the natural, but Portland cement has been found to be the best 
to use for waterproofing purposes. For coating sea walls and other 
marine constructions, puzzolan or slag cement mortar is well adapted. 
For coating exterior concrete wall surfaces and interior surfaces of 
cisterns or tanks, and especially any masonry below ground-water 
level, Portland cement mortar in proportions 1 : 1 or 1 : 1J will 
create watertightness. The mortar should preferably be applied 
against the surface which is to come in contact with the water. 

FIG. 7. Applying Bituminous Coat with Brush to Arch of Culvert. 

But where a good hold can be secured for the mortar and if made 
thicker than J of an inch, it may be applied to the other side. In 
Table XXXII are given suitable thicknesses applicable to varying 
heads of water. Where imperviousness is desired both ways, both 
sides should, of course, be coated. Increased watertightness will be 
secured under all conditions, whether the mortar coat be applied 
by hand or machine, by troweling the surface to a granolithic finish. 
However, this granolithic finish must be produced with the greatest 
care, otherwise it will vitiate its purpose. 

* Taylor and Thompson, " Concrete, Plain and Reinforced," 2d Edition. 



Use of Lean and Rich Mortars. The use of lean or rich mortar is 
mainly dependent on the purpose each is to be put to. Mortar 
contracts on drying and expands on wetting, hence cracking invari- 
ably results. This is greatly reduced by reducing the proportion 
of cement, which alone is affected and causes the cracks. In stucco 
work or on other superstructural applications the leaner mortar 
is most advisable. The sand should be graded so that the pro- 
portion of medium-sized grains is small, and the coarse and fine grains 
are about equally mixed. 

Experience shows, for instance, that a plain 1 : 3 stucco, prop- 
erly applied, remains free from cracks, but is rather porous. A 1 : 2 
stucco, however, while less porous, is subject to considerable crack- 
ing, unless well protected during the setting period. But such pro- 
tection (i.e., protection against freezing, or exposure to the sun and 
quick drying out) besides being a good deal neglected, is often 

12 Concrete 

FIG. 8. Swimming Pool Waterproofed with Waterproof Mortar Coat. 

Hence it resolves itself to a question of how to make stucco 
mortar lean enough to avoid cracks, yet dense enough to be damp- 
proof. This difficulty is often overcome by the use of a suitable 
integral waterproofing compound, or a surface coating material 
which evaporates slowly and leaves the surface pores filled. 

Since the strength of mortar* here is of least consideration, and 
absolute impermeability of the mortar of secondary consideration, 
(i.e., the mortar for stucco work need but be made dampproof) these 
waterproofing materials find a very good field of usefulness. But 
the indiscriminate use of such compounds as, for instance, soap and 
alum washes, caustic potash, stearin and resin compounds, or 
chloride of lime and other metallic salts, or, for that matter, any 
of the many waterproofing or dampproofing compounds, without 
test or careful investigation is unwarranted. The architect who 
specifies any of these compounds without investigating or experi- 
menting (and all too many do so) to ascertain their value for this 


particular purpose is wasting his clients' money and hazarding his 
own reputation. The many worthless and the few worth while 
compounds on the market make it imperative to search most con- 
scientiously for a material that will not wash out after a few rain 
storms; that will not discolor or disintegrate, or induce disintegra- 
tion; that will prevent hair checks and remain cementitious while 
creating imperviousness in the stucco, and that will not induce 
peeling or blistering of the stucco. Service and practical tests are 
the best, and in fact, the only means for determining the effectiveness 
of any of these materials. 

In connection with the use of a large proportion of cement in 
mortar or excess cement in concrete, it must be borne in mind that 
the practice is wrought with many dangers for vitiating its ostensible 
purpose, i.e., increasing the density of mortar or concrete. For 
underground construction this practice is entirely warranted and 
efficacious, but for superstructural work of any sort this practice is 
successful only on the performance of the work with the most pains- 
taking precautionary measures for curing, drying, and seasoning the 

Only a few of the many patented cements and bituminous paints 
on the market for waterproofing by the surface coating system 
possess the requisite properties for efficient usage. In general, these 
properties are : (a) That absolute dampproof ness or waterproof ness 
be effected by their use; (6) reasonable cheapness; (c) applicability; 
(d) durability. Experience and experiment have shown that only 
a very few of these special dampproofing and waterproofing com- 
pounds possess the same effectiveness as a moderately thick coating 
of neat cement or cement mortar, the latter of a maximum thickness 
of about 2 inches for the most adverse conditions. 

Cement mortar, as ordinarily mixed, can be made practically 
impervious by the addition of alum and potash soap. One per cent 
by weight of powdered alum added to the dry cement and sand and 
thoroughly mixed, and about 1 per cent of any potash soap (ordinary 
soft soap) dissolved in the water used in mixing the mortar will make 
it remarkably impermeable, but the results are not lasting. A dry 
clay mixed with cement in equal proportions and applied as a coat- 
ing is also effective as a waterproofing agent, provided any form of 
cracking is prevented. 

A surface coat of cement mortar of a thickness and proportion 
best judged from requirements at hand, is sometimes used for 
creating a dry surface upon which to apply a different system of 



The impermeability of plain cement mortar is well shown in 
Table III, which is adapted to our purpose from the United^ States 
Bureau of Standards, Technologic Paper No. 3. 


Proportion by 
Volume of 
Portland Cement 
to Meramic River 

Ago in Weeks 
when Tested. 

Cubic Millimeters of Water Passed per Minute per 
Square Centimeter of Surface Subjected to 1.4 km. 
(3.1 Ib.) Hydrostatic Pressure.* 

Thickness of Test Pieces in Inches. 




1 :2 




1 :4 






1 :6 










. 19 



1 :8 













* Average value of three test pieces tested for six hours. 

Application of Powdered Metal. The waterproofing effective- 
ness of powdered metal, such as powdered pig iron or other iron oxide 
depends upon the barricading effect of its increased bulk due to 
corrosion while it is held in suspension in the gaging water, which, 
of course, permeates the mass. When mixed with the cement, 
which is the most usual way, the moist particles of iron oxidize and 
expand, thus filling the voids in the concrete mass; or, when applied 
to the surface of concrete, either as a slush coat or thin mortar coat, 
its action results in the production of a hard, dense, and impervious 
finish. The corrosion is often assisted by the addition, in very small 
quantities, of some oxidizing agent such as sal-ammoniac or sulphur. 
This same mixture is often used, under various trade names, as a 
concrete floor hardener. In fact, powdered metal finds its greatest 
usefulness in this field. When so used it should be floated on the 
surface and then finished off with a trowel. Success in the Use of 
this material necessitates the employment of very careful and skillful 


labor. Quantities and rules for applying powdered metal are usually 
issued by the manufacturers of these materials, and should be care- 
fully followed. 

The Sylvester Process. The use of soap and alum solutions for 
coating a masonry surface is known as the Sylvester Process of damp- 
proofing and waterproofing. It is applicable alike to concrete and 
other masonry. It does not, however, form a permanent water- 
proofing, and is not much used at the present time. In using these 
materials the following precautions must be observed: (a) Each 
should be perfectly dissolved before being applied. (6) The masonry 
surface should be dry and clean before application, (c) The air 
temperature at the time of application should be between 50 and 60 
deg. Fahr. (10 and 15.5 deg. Cent.), (d) The soap solution should 
be boiling hot and applied first, using a flat brush for this purpose. 
The alum solution is then brushed on at a temperature between 60 
and 70 deg. Fahr. (15.5 and 21 deg. Cent.), thoroughly covering the 
first coat. An interval of one day should elapse between the appli- 
cation of each set of coats. The number of coats is dependent 
on local conditions, including water pressure and exposure to the 

The proportion of soap and alum giving the best results is f pound 
of castile soap to 1 gallon of hot water; J pound of common alum 
to 4 gallons of lukewarm water. The action is chemical. The two 
materials combine to form a stearate of aluminum, which fills the 
voids in the concrete and is insoluble in water. A solution con- 
sisting of 1 pound of concentrated lye, 5 pounds of alum, and 2 
gallons of water, applied while the concrete is green and until it 
lathers freely, has been successfully used. A cheap and effective 
substitute is a mixture of. 1 part of aluminum sulphate and 3 parts 
of hard soap, by weight. This may also be used as an integral 
compound, in proportions determined by experiment, for mass 
mortar or concrete. 

Application of Paraffin. The application of paraffin is universal 
and adapted to all classes of masonry above ground. If applied 
cold it is specially treated, e.g., it is boiled to rid it of water, the 
presence of which renders it difficult to apply, and dissolved in a 
highly volatile compound. Being an almost colorless, translucent 
liquid, it does not change the color of the surface to which it is 
applied. It is easily applied with a stiff flat brush, and the best results 
are obtained by thoroughly rubbing it into the surface, using three 
coats if the surface is rough. If the surface is clean and smooth, 
two coats are sufficient, because the solvent has a high penetrating 


capacity, by which function it leaves the pores filled with paraffin 
after the volatile matter has evaporated. Most paraffin compounds 
are prepared for use by the manufacturer, who usually issues direc- 
tions for their application, but ordinary commercial products 
may be used. In general, however, the following precautions should 
be observed: (1) The surface treated should be made smooth 
and dry, the first by chipping all projections and rubbing with a 
stiff wire brush if necessary, the second by doing the work after a 
dry period. (2) No fire should be near the material when applied, 
because the volatile solvent is very combustible. 

If the paraffin is to be applied hot, it is merely melted and 
thoroughly rubbed into the surface, which has been previously pre- 
pared and warmed, to be waterproofed. The latter is most economic- 
ally done with improvised salamanders, using charcoal as fuel. If 
dissolved in the proportion of one-third paraffin and two-thirds 
kerosene, it remains soft longer and penetrates the stone further. 
Paraffin is the very best waterproofing material for exposed work 
of all kinds, but needs to be applied by men experienced in this work. 
With a sufficient penetration, durability and effectiveness is assured 
because of the natural inertness of the paraffin. 

Application of Bituminous Compounds. There are many bitumi- 
nous paints, pastes, and enamels offered by manufacturers for use in 
the surface-coating system of waterproofing. Compounds of this 
nature are also used for dampproofing. When used for this purpose, 
the film or coat is usually applied somewhat thinner than for water- 
proofing. For the latter purpose, the film or coat does not exceed 
J inch, except when the material is a bituminous mastic, in which 
case it is applied in thicker form. If employed as dampproofing for 
exposed walls of buildings or other superstructures, these bituminous 
compounds are usually applied on the interior or between wall sur- 
faces. As waterproofing, these compounds are applied either on the 
exterior or interior surfaces of underground works, depending on 
conditions. In structures already erected some of these compounds 
are well adapted to remedy leaky conditions because they can 
be applied on the inside and sometimes to a moist surface. 
This obviates the expense of excavating around the foundation. 
Allowing bituminous waterproofing materials to remain in direct 
contact with earth or other backfill, i. e., unprotected, is poor practice 
because the acids or alkalies present in the backfill will eventually 
destroy such materials. Bituminous coatings are sometimes applied 
to the inner surface of foundation walls and tunnels even where a 
water pressure exists, but they are not dependable to withstand 


this condition unless backed up with an inch or two, or more, of 
cement mortar or concrete, and the work done with care. 

A priming coat should always be used before applying liquid 
bituminous surface coatings to waterproof a structure, and in this 
connection field engineers and inspectors will do well to guard against 
the following practices: (1) Failure to apply a continuous priming 
coat; (2) the use of a viscous material as a priming coat. On cer- 
tain construction work, especially municipal work, it is often to the 
advantage of the manufacturer or his agent to supply material of 
the same consistency for the priming coat as for the other coats, 
because very much more of it is required for the first than for the 
succeeding coats on account of the usual roughness of the surface. 
The waste of material, however, is the least objectionable in this 
case. The serious nature of such practice lies in the failure to utilize 
the priming coat for what it was intended to accomplish, namely, 
to enter the surface pores of the concrete or other masonry, to find 
every little depression or small hole and coat it, and to assure the 
adhesion of the coats which follow. These objects are not well 
accomplished by using a viscous material for a priming coat. The 
right consistency of a priming coat is one as liquid as water or milk, 
in which state it can penetrate deeper below the surface. 

The composition of most surface coating compounds is kept 
secret by the manufacturer, and the only real safeguard one has in 
purchasing them discriminately is to observe the results on structures 
already waterproofed with any of these products. In general, the 
following precautions should be observed when buying and applying 
such materials: (1) Chemical test on a representative sample of 
the material should show (a) preponderance of bitumen, (6) resistance 
to acids and alkalies, (c) strong adhesion to concrete or other ma- 
sonry, (d) toughness at low temperatures. (2) Results of tests on 
representative specimen should be checked with material as received 
and then applied according to the manufacturer's directions. (3) 
The surface to be waterproofed must be made clean and dry, 
applying not less than two coats; the first coat, usually a primer 
(that is, the same material, or ordinary asphalt or tar, thinned to a 
more liquid consistency) is allowed to become dry or nearly so, 
before the second is applied. (4) Great care is required (a) to 
obtain a continuous film of coating, (6) to fill all corners, recesses and 
depressions, (c) to leave the final surface roughened, yet coated, 
if a plaster or mortar coat is to be applied directly on the film, (d) 
not to injure the film in applying these coats, and (e) not to expose 
the applied material unduly. 


Straight-run coal-tar products are often and successfully used 
in the surface-coating system of waterproofing. For example, in 
protecting abutments and retaining walls from disintegration due 
to their natural permeability, various dampproofing bitumens are 
successfully and cheaply made and applied, of common creosote oil 
and coal-tar pitch. The creosote oil is applied first and penetrates 
the wall to a degree depending on its quality and the density of the 
masonry, and this is followed by at least two moppings of the coal- 
tar pitch. In some instances where the concrete is very porous, a 
third and fourth mopping may be required in order that the entire 
surface may be well covered. Dull spots on the surface are evi- 
dence that the pitch has only penetrated into the pores of the con- 
crete but the outer surface is not completely coated. A mixture 
of coal-tar and powdered slate of the consistency of molasses is often 
used for similar purposes. Occasionally, a 2 or 3-ply felt- and pitch- 
membrane is applied to such structures. 

Instead of the tar products, refined asphalts of good grade may 
be also used. Where a first or priming coat is required, and it is 
practically always advisable to apply one, this usually consists of 
asphalt diluted in naphtha or gasolene. Of course, both the pitch 
and asphalt must be of a consistency and melting-point to withstand 
the local climate or special condition of the work. Either of these 
materials will be benefited by a protective coat of some form, especi- 
ally when this waterproofing is in the form of a felt or fabric mem- 
brane. A bituminous paste composed of chinawood oil, asbestos 
and pine tar is well adapted for such and similar purposes, but its 
consistency and application must be carefully watched. Coating the 
surface with boiled linseed oil until the oil ceases to be absorbed is 
another method that has been used with success. In Chapter IX 
are to be found various formulae of compounds usable for damp- 
proofing and waterproofing purposes. 


Definition, Purpose and Development. The membrane system 
of waterproofing refers to : (1) a built-up, elastic, continuous bitumi- 
nous blanket or membrane composed of one or more layers of water- 
proofing felt or fabric cemented together with asphalt or coal-tar 
pitch, and which more or less completely surrounds the structure 
waterproofed; (2) metal linings, which usually also constitute an 
integral part of the structure, as in steel-plate or ring tunnel 


tubes* wherein the metal lining is protected within and without by 
masonry. (3) Any method or material which permits the more or less 
complete enveloping of a structure to prevent the passage of water 
through its exterior parts, but which is itself not in direct contact 
with the water, that is, which is itself protected by some other cover- 
ing. Such protective covering may be of concrete, vitrified hollow 
tile, or brick in cement mortar and sometimes a layer of mastic. 

The purpose of the membrane system of waterproofing is princi- 
pally to waterproof structures in course of erection, particularly those 
below ground surface, such as subways, tunnels and building founda- 
tions; but it applies equally well to retaining walls, arches, reser- 
voirs, etc. It is not so well adapted to the waterproofing of structures 
already erected or to remedy leaky conditions developing subsequent 
to erection, owing to the fact that the membrane must be applied 
to the outside of the structure, thereby usually necessitating con- 
siderable excavation. 

In the very earliest times, asphalt was used simply as a surface 
coating, that is, to serve as dampproofing. In this condition it was 
not well adapted to resist water pressure, even when placed between 
two masonry surfaces. To overcome this defect, fibrous paper was 
introduced between these surfaces, with a coating of bitumen on 
either side. For greater water pressures, the number of plies of 
paper was increased, each being coated with bitumen as applied. 
Paper was gradually superseded by waterproofing felt; this was 
largely composed of rag and wool, or pulp. The wool variety of 
felt has had until comparatively recent times a very extensive use, 
but because of the unreliable quality of wool purchasable now, and 
to an extent, its high cost, rag felt and pulp felt are now more com- 
monly used. These felts are now in sharp competition with cotton 
and jute fabric. Commercially, refined asphalt and coal-tar pitch 
have been used for a long time in connection with the treatment of 
paper, felt, jute and cotton fabric, and also as a binder for forming 
waterproofing membranes of these materials. Now there is some- 
times incorporated in these bitumens mineral fillers, such as shredded 
asbestos for instance, for the purpose of increasing their plas- 
ticity and substantiality 

Applying the felt or fabric membrane to a structure calls for 
certain precautions which can ill afford to be neglected. These pre- 

* Metal linings or castings may be used anywhere, but especially where 
great stresses are anticipated or where it is practically impossible to apply the 
ordinary membrane. This type of construction, however, requires special 
design for each case, 


cautions are embodied in three fundamental requirements to be care- 
jfully observed in order to insure good waterproofing by the membrane 
system. These are (1) surface preparation; (2) continuity of 
membrane; (3) protection of membrane. 

Surface Preparation Prior to Application of Membrane. It is 
impossible to make a bituminous sheet adhere properly to a wet or 
rough masonry surface, but it is advisable to make it adhere to what- 
ever surface it is applied. The surface to be waterproofed should, 
therefore, be prepared by chipping all projections and smoothing off 
with mortar and trowel all depressions; cleaned by sweeping or 
scraping off all foreign matter of whatever nature ; dried (when water- 
proofing must proceed during rainy weather, or before the concrete 
has completely dried after setting), by heating the surface, if not 
large, with a gasoline torch, by burning gasoline on the surface to 
be waterproofed, or by employing salamanders; or again, by pro- 
viding a temporary drainage system that will keep the surface dry 
during the application of the waterproofing. If these measures are 
impracticable or insufficient, then one or two plies of felt, with the 
first laid dry, that is, without a bituminous binder on the under side, 
and nailed to or against the wet surface, if necessary, will create a 
dry area for the application of the waterproofing proper. Where it 
is difficult or impossible to apply this dry-ply, as on arches of tunnels, 
a thin sheet metal lining nailed to the masonry, or a cold application 
of asphalt dissolved in naphtha, or a reasonably thick plaster coat 
of neat cement or mortar, provides a dry surface on which to start 
waterproofing. Of course the concrete in all cases must be thoroughly 
set before any waterproofing is applied. As an illustration of how 
such problems are met in practice, may be cited the following 

In building the east face of the south Manhattan shafts of the 
Pennsylvania Railroad tunnels,* preparations were made to place 
the felt and coal-tar pitch waterproofing in the ordinary way, but 
it soon became necessary to drain away water that was running down 
over the face of the wall from the exposed rock above. To accom- 
plish this a drain was constructed on the face of the wall near its 
top. This consisted of a strip of tin set in a ridge of plaster of Paris 
stuck on the face of the wall. The drain had a slight grade down- 
ward. It answered the purpose very well, allowing the wall to 
dry out below the drain. This type of drain was found useful at 
many points, because it could be applied quickly and at small 

* Transactions, American Society Civil Engineers, Vol. 69, p. 80. 


Necessity of Continuity of Membrane. Continuity of the mem- 
brane is more important than the preparation of the surface to be 
waterproofed, for it is not always necessary to make the membrane 
adhere to a surface as long as the sharp projections have been removed 
and a reasonably smooth surface obtained; but lack of continuity 
creates a condition directly opposed to the purpose of waterproofing; 
for water will find the break, large or small, percolate through it, 
and be a source of annoyance at first and danger at last. 

The continuity of a waterproofing membrane may best be secured 
by breaking joints systematically and leaving sufficient lap to form 
a good connection with the adjoining section. In applying the 
bituminous binder it is necessary to avoid blowholes, " dry spots," 
and other common defects. But these dangers are partly obviated 
by the very method of building up a membrane (see Fig. 14). In 
using either felt, fabric or cotton drill for this purpose, such defects 
will be greatly reduced by lightly pressing into the hot binder, which, 
incidentally, prevents " kinks " and also insures better adhesion 
between successive plies as well as to the original surface. Where 
the fabric is of the open mesh variety, the formation of air pockets 
between successive plies is automatically prevented, and pressing 
it into the binder will insure the filling up of all the interstices of the 

Where a connection is made between a wall and roof of a structure, 
the lap should be about 1 foot wide. The successive plies of the 
membranous mat forming the lap on the wall should be interwoven 
with those of the roof mat and stuck fast against the side of the wall 
with binder. In joining the floor membrane with that on the wall, 
the latter should be interwoven as shown in Fig. 9A, with the lap 
ends of the floor membrane turned up an amount depending upon 
local conditions, but never less than 6 inches. 

One of the most important matters in regard to the continuity 
of the waterproofing membrane, and one requiring careful attention, 
is the joining of new work to old. The old waterproofed surfaces, 
or the old laps, should be cleaned of all foreign matter, and, where 
necessary, softened by heating, as explained in " Surface Prepara- 
tion." Such laps should receive a coat of bituminous material 
before the new strips of fabric are applied and pressed down 
as previously explained. Where possible, a mesh joint should 
be made of the laps of the old and new fabric as the plies are laid up. 
After long exposure of a portion of a membrane or its end lap, as 
on an uncompleted portion of work, the felt or fabric may have 
deteriorated or have been torn off. It is absolutely necessary to 



provide sufficient lap width to properly join the old and new water- 
proofing; hence the safest expedient is to recoat the membrane with 
a thick binder film in the first instance, and to cut back at least 6 
inches of the concrete or other masonry to secure sufficient lap in 
the second instance. 

:*' *SSSi^-te? 4-f^\ f^ssKxy^Sfxn: 




FIG. 9. Methods of Applying Membrane Waterproofing to Walls and Footings. 

Protection of Membrane. The third fundamental requirement 
of the membrane system of waterproofing is the protection of the 
membrane during construction, but more particularly after. During 
construction the waterproofing membrane may be injured by the 
workmen carelessly throwing about iron tools which sometimes 
puncture the membrane. The placing of temporary struts on the 
membrane may have a similar effect. Dumping of bricks and the 
unrestricted hauling of material, or walking on the membrane is 
particularly harmful to its continuity. A waterproofing membrane 


appHed to vertical masonry tends to sag and produce a rippled 
surface, especially in warm weather or when a particularly soft 
binder is used. In fact, no bituminous membrane, no matter how 
well applied or what binder is used, will stand up completely intact 
without support of some sort under such conditions. 

After construction the waterproofing membrane may be injured 
by the impact of stones in the backfilling material, or by the large 
aggregate in the protective concrete if this is deposited from an 
undue height; or by bulging and running of the bituminous material 
due to heat, or cracking and chipping due to cold. Where there is 
any considerable hydrostatic pressure behind the membrane it may 
be perforated in a weak spot, or where a slight bulge or " ripple " 
has occurred in it, the added weight of the water on the bulge may 
drag the membrane down. 

A serious menace to bituminous membranes surrounding under- 
ground structures arises from leaks in gas mains and sewers in city 
streets. All gas mains collect a kind of a pungent oil called gas-drip, 
which frequently comes out of leaky joints in the mains, saturating 
the ground over considerable areas. This oil will, in a comparatively 
short time destroy a portion of a waterproofing membrane by dis- 
solving the bituminous binder, and, where felt is used, turn it into 
a soft, mushy and worthless material. Then again the membrane 
may be attacked by lubricating oil and other solvents from leaks in 
underground pipes or from machinery, as for example, where switch 
pits for surface railroads are in close proximity to the waterproofing 
of the structure. 

Nearly all sewers, besides carrying sewage (which is sometimes 
acidulated and sometimes alkaline), carry steam and other gases, 
and where leaks occur, which happen quite often, the ground becomes 
saturated over a considerable area. The deleterious effect on the 
membrane in this instance is quite the same as in the case of gas-drip 
or oil, but not so marked. 

Again, if a membrane is injured in any way, then the worst and 
perhaps the only serious drawback of the membrane system of 
waterproofing is encountered. The leak in the membrane is usually 
inaccessible from the outside without costly excavation, and cannot 
be gotten at on the inside except by removing considerable masonry. 
But what is still worse, it is almost impossible to tell where to begin 
excavation or tearing out the inner masonry, due to the fact that 
water is likely to travel a long way between the membrane and the 
wall so that the location of the leak or leaks on the inside may be as 
much as 150 feet from the injury in the membrane. This, incidentally, 



emphasizes the need for making the membrane adhere to the 

To avoid possible injuries to the membrane during construction 
due to the causes mentioned above, temporary protection should be 
provided according to circumstances; for example, on the floor 
of a structure, by laying a gang-plank or enclosing the area with 
an improvised board fence; or if on a wall, by bracing strips of 
wood against it, especially to hold up the loose lap of the membrane 
and not allow it to dangle. Other expedients will suggest themselves 
as the need arises; the important thing to remember is that any 
properly designed protection will greatly minimize the above dangers. 

After construction there should be placed on or against the water- 
proofing a protective coat of metal at the most vulnerable points, 

2 Layers of Brick / 4* 0" Sewer 

in Asphalt Maetic 

FIG. 10. Roof of Ventilating Chamber Waterproofed with Sheet Lead Membrane. 

and a protective coat of cement mortar or concrete, 2 to 4 inches 
thick, over the rest of the waterproofing. Fig. 10 shows one way 
of avoiding these dangers, by substituting a sheet lead trough 
for the regular waterproofing between a sewer and the top of a bay 
over a subway ventilating chamber. The protective concrete 
should preferably be reinforced, though this is not always necessary. 
A course or two of bricks, or a wall of flat or hollow terra-cotta tile 
are also good protective mediums. On horizontal surfaces, the 
hollow terra-cotta tile should not be used. The 3- or 4-inch concrete 
protective coat is the best in most instances because it is the least 
pervious. But in all cases the protective medium should be com- 
plete and cover every inch of membrane, and not as shown in Fig. 
11 or Fig. 12A. Fortunately engineers are fast learning the folly 
of such malpractices as are depicted in these illustrations. 



Then again, in protecting waterproofing membranes or surface 
coatings, insufficient consideration is often given to the end laps. 
Yet it is no less important and necessary to protect the ends than 
the rest of the membrane or surface coating. It should also be 
observed that in placing the protecting covering of whatever material, 
it is of primary importance not to make water seams of construction 
joints; in other words, joints in protective coverings or layers should 
be made to offer the greatest resistance to the passage of water. 
A case in point is well illustrated and self-expkiced in Fig. 12 
wherein the conditions referred to here are manifested in a striking 


Exposed Membrane 

FIG. 11. Application of Waterproofing Membrane with Insufficient Protective 


way on a very important work. The improved methods of pro- 
tecting such ends are simple, easily constructed in the field, and 
cheap from every point of view. A waterproofing membrane of any 
material or a surface coating of bituminous material will last very 
much longer and render better service when properly protected. 
In fact, even a 1-inch mortar coat is remarkably effective in this 
direction, and is sometimes used even on bridge floors. But, in 
general, for railroad bridges, which are subject to considerable 
vibration, a sheet mastic of about this thickness is preferable. 

It is best to place the protective medium not later than one or 
two days after the waterproofing is completed. Where concrete 
constitutes the protective medium, it should be poured from the 


least height possible, as depicted in Fig. 13. Also, in depositing 
heavy backfill on or against such a comparatively thin layer of 
concrete, care and judgment must be exercised not to break or 



Note exposed 
lap of 
membrane S 

4, c Concrete /Wate^oofing f N te overla PP in & of Protective concrete . 

*- * \ \ A r- 


T -^ * 

Crown of Arch / -_[ 

Crown of Arch 

i . 

f Crown of Arch 



in Earth . 

11 / --- 






K / 



v If 



-3 ; 

. 3 

\ ^C) 


** o 




Extra single row of 



brick in mastic surrounded 

Proposed 1 

n Alternate method of 

Line indicated 
on drawings. 
Line actually 
worked to in s 
the field. 
Note construc- 

L 1 \ 


by membrane to imped 
passage of water wind 
may enter construction 
joint ^ 

Construction joint.- - 


position of 1 

J ^i{ 

impeding water which 
may enter construction 
joints by lowering con- 
struction joint at least 
to the depth of one brick . 





H- . 

tion joint. 










Baee of 

E = 









1 1 '" T 1 1 1 I I 

-* i 

1 1 1 1 1 1 

1 1 1 1 1 1 

,- 1 Ply Waterproofing 



FIG. 12. Good and Bad Practice in Membrane and Brick-in-mastic Water- 

crush it. A practical and instructive illustration of this danger 
is given in the following instance : 

On the New York Terminal of the Pennsylvania Railroad Tunnel 
Extension, the protective cover over the waterproofing membrane 
was designed to be of plain concrete from 5 to 6 inches thick. As 
long as the backfilling was kept well back of the completed work 


and was stepped off in bench formation, the plain concrete cover 
served its purpose; but in one case, when the backfilling was advanced 
in bank formation close upon the completed construction work, 
the concrete cover broke and the waterproofing was damaged, 
requiring the removal of much backfilling to effect proper repairs. 
After this occurrence, the cover was reinforced with wire cloth and no 
further trouble was experienced. 

Methods of Applying Membrane Waterproofing. In applying the 
membrane to any masonry surface, the latter is first mopped with 
bitumen, then the first strip of felt or fabric is unrolled thereon, 
tightly stretched, smoothed, and pressed into the film of bitumen. 
This strip is best made continuous over the width or length of the 

FIG. 13. Height from which Protective Concrete Should be Poured on Water- 
proofing Membrane. 

structure where possible. In this " continuous type " the second 
strip is laid to break joint with the first in a manner depending upon 
the number of plies usod. The various methods of building up a 
waterproofing membrane are shown in Fig. 14. The portion of each 
strip of fabric to be lapped should be carefully mopped as the next 
strip is laid over it. When several strips have thus been laid, the 
second ply is similarly laid, then the third, fourth, fifth and sixth 
plies, as required. As each strip is laid or applied, it is important 
to see that no kinks have formed at the lap joints, for this leaves an 
opening for water to enter either between or under the membrane. 
The top ply should always be mopped completely over the entire 
surface, leaving no bare spots or other imperfections. See Table 
XXXII for the number of plies necessary to resist various heads of 
water up to 42 feet. 





One Ply 

Two Ply 

Three Ply 


One Ply 


Two Ply 

Six Ply 

FIG. 14. Four Methods of Building up Waterproofing Membrane. Applicable 
to either Felt or Fabric. 



Making Membrane Mats. Where it is impossible to build up 
the membrane directly on any part of a structure, due to physical 
obstructions, a mat of the required number of plies may be laid 
up and completely formed in any convenient place and applied as 
noted below. This mat is best made as follows: The required 
length of felt or fabric is rolled out on some clean surface, and the 
top surface of the strip mopped; then the second strip is placed 
thereon, breaking joint at the one-third, one-sixth or other portion 
of the width of the lower strip, depending upon the number of plies 
required. After mopping the second strip, the third is applied, 
making an equal lap with the second strip, and so on. The completed 
mat then receives a top coat of bitumen and is applied on the work 
in a manner similar to applying separate strips of fabric; that is, 

Single 3-Ply Mat before Laying -, 

Concrete Surface* 



FIG. 15. Method of Making Membrane Mats. 

the concrete surface is first mopped to receive the mat. Each mat 
should lap over the membrane and other mats already in place, at 
least 4 inches (see Fig. 15). In no case should the mats be placed 
so that the membrane formed has less than the specified number of 
plies in the membrane proper. All exposed joints must receive a 
final mopping and be made as smooth as possible. When a portion 
of the structure being waterproofed is on a gradient, care should be 
exercised in making and applying the mats so that the joints lap 
each other in the direction of the down grade of the structure. This 
precaution applies as well to the application of any built-up mem- 
brane, whether vertically or horizontally applied. 

Connecting New and Old Membranes. Joints form the weakest 
part of a membrane; therefore too much care cannot be exercised 
in making a joint between an old and new membrane by a proper 


lap. Joints should be so made as to form as little bulge in the 
membrane as possible, but no butt joints should be used on any form 
of waterproofing. Laps exposed for any length of time should be 
carefully examined for any defects before connecting up, and where 
any defects or insufficient lap areas are found, the concrete or other 
masonry should be cut back sufficiently to give a proper lap between 
the sound membrane in place and the new work. Laps should not 
be less than 4 inches wide for each strip of fabric, or in any case not 
less than a total of 1 foot. 

Timbers and temporary struts interfering with the proper applica- 
tion of waterproofing membranes present peculiar difficulties, and 
their locations require very careful workmanship and close inspec- 
tion. The best method to insure the proper and complete water- 
proofing of the holes left by the removal or shifting of such false 
timbering, especially when they are located in poorly illumined 
and cramped areas, is as follows: All posts, struts or other tem- 
porary supports, whether on a floor or roof, or against a wall, should 
be shifted so as to avoid breaking the continuity of the membrane, 
otherwise holes are left not waterproofed. Where it is impossible 
to so shift these posts and holes must be left in the membrane, then 
it is necessary to paint these posts red or white, or otherwise to 
distinctly mark them, in order that they may be identified later 
when removed and the space occupied by them waterproofed. In 
waterproofing the space left by the removal of a post, or other sup- 
port, a strip of fabric is cut to a size not merely sufficient to com- 
pletely cover the space, but large enough to lap 2 inches on every 
side of the waterproofing in place as illustrated in Fig. 16; this total 
area is then mopped and successive plies of fabric are applied in the 
usual manner. Each strip should extend with a 2-inch lap over the 
one directly underneath it. The entire patch should then be 
thoroughly and heavily coated with bitumen. In no case must the 
fabric be cut to fit only the space occupied by the opening. Pre- 
pared mats fitted into the hole is also poor practice. 

Placing Membranes around Projections and in Vicinity of Steam 
Pipes. Where pipes or rods project through parts of a structure 
that are to receive the membrane waterproofing, it is very important 
to make an absolutely watertight joint around these objects. These 
joints are best made as follows: As the first ply of felt or fabric is 
applied or laid against the surface, a hole should be cut in it fitting 
snugly around the previously cleaned and mopped pipe or other 
projection. Then a fairly large strip of felt or fabric, as the case 
may be, is placed completely around the object so that half adheres 







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to it and the other half slitted radially adheres to the first ply on 
the wall Or other surface. The successive plies are laid in the same 
manner. A finishing ply is then placed covering the slitted fabric 
and this ply is cut only to allow the pipe to pass through. 

Satisfactory and permanent waterproofing in the vicinity of 
steam pipes is difficult to obtain. This may be accomplished, 
however, by placing a strip of sheet lead of sufficient length and 
width, and about J-inch thick, between the waterproofing and the 
supporting material of the steam main. It is understood, of course, 
that the main -itself is first adequately insulated to prevent its radia- 
ting heat from affecting the waterproofing. A satisfactory method 
for insulating steam pipes is to surround them with a blanket of ten 
or twenty plies of untreated asbestos felt, encasing this with large 
semi-sections of vitrified sewer tiles, and packing the space between 
the two with coarse asbestos fiber. The whole must be well sup- 
ported on concrete or vitrified two- or four-way tile ducts or other 
suitable non-conductive material, all depending on the size of the 
steam main, location and working conditions. 

The above expositions are general. Modifications will often be 
necessary on such structures as railroad bridge floors, reservoirs and 
buildings, but the fundamental principles are the same. Hence, 
it is not necessary to consider here how each kind of structure is to 
be waterproofed. The main point to remember in regard to all 
types of waterproofing and all manner of structures is to suit the 
waterproofing to the structure, taking all local conditions in to con- 
sideration, including climate, purpose and type of structure. In 
the majority of cases, it may here be noted, successful and durable 
waterproofing depends not only on conscientious labor, but more 
particularly on expert supervision. 

Use of Special Membranes. A modification of the usual long- 
strip, built-up, elastic type of membrane consists of a membrane 
made up of small, square layers of cotton fabric,* thoroughly satu- 
rated and heavily coated on both sides with a suitable bitumen 
and often with a special, that is, a proprietary bituminous compound. 
The cotton fabric commonly used has a thread count of 66 by 44 per 
square inch, weighing about 4| ounces per square yard. When 
treated, the fabric has an average thickness of J inch, and weighs 
about 4| pounds per square yard. The operation of saturating 
and coating the strips of fabric is done in the field immediately 
adjacent to the work because the compound used must possess 
considerable adhesiveness so as to stick well to the applied surface 

* Developed in 1907 by Oscar Sheffield, and in practical use since 1909. 



and to itself when lapped to form the membrane, hence it is imprac- 
ticable to handle the finished sheets between the factory and the 
field work. 

The treated sheets, which are best handled when about 1 yard 
square, are laid over the surface to be waterproofed with not less 
than a 2-inch lap. The laps are then sealed with a hot smoothing 
iron to insure perfect adhesion, after which they are recoated with 
an additional layer of the bituminous compound. The membrane 
is laid so as to be continuous and unbroken over the entire area 
waterproofed. See Fig. 17. The protective masonry is then applied 
as on the built-up membrane. 

FIG. 17. Applying Treated Cotton Fabric. 

Any good quality of cotton or jute fabric is suitable for this type 
of membrane, but only a strongly adhesive, tough and elastic 
bitumen, and one that will remain plastic at all seasons, can be used 
satisfactorily for this purpose. At the present time only one pro- 
prietary compound is extensively used for this modified membrane. 
This compound consists of several hydrocarbons, each possessing 
different physical properties but mixed in proportions to secure the 
desired consistency. 

Considerations for Selecting Membrane Reinforcement. The 
following question often arises in waterproofing design: What 
reinforcing material is best adapted for the membrane system of 
waterproofing? In other words, is treated felt, jute fabric or cotton 
drill to be preferred, and under what conditions or for what types of 


structures is each best suited? This can best be judged and answered 
from experience. Felt was used extensively on the old Manhattan 
subways in New York City, in the form of a membrane composed 
of six plies of felt and seven coatings of asphalt, surrounding the 
structure like an envelope. But it has not given entire satisfaction 
apparently because this type of membrane has insufficient tensile 
strength, so that when cracks developed in the concrete shell, it too 
would break somewhere. Had this membrane been reinforced 
with two or three plies of jute or cotton fabric, this fault would not 
be operative in producing leaks. Then again, the felt in the mem- 
brane forms a stratified sheet with as many laminations as there are 
plies used. This creates many surfaces where water may creep 
along under certain conditions, and cause damage. Its close texture 
also prevents the escape of entrained air during its application, 
which tends to create air pockets between the plies. Besides, there 
is also present the capillary action of the felt fibers, though this is 
not peculiar to felt alone. It has, however, a very extensive and 
successful use on all manner of structures notwithstanding, and is 
cheaper per unit of area than either cotton or jute fabric. 

Jute fabric, on the other hand, such as was used on the new 
Dual Subways in New York, also in the form of a membrane (com- 
posed of three to six plies of fabric with from four to seven coatings 
of coal-tar pitch) , has thus far given entire satisfaction, and apparently 
for the following reasons : The fabric being of the open-mesh variety 
(and only such was used), permits the bonding of successive plies, 
thus forming a unit-membrane of bituminous material with the 
fabric acting as so much reinforcement. The open mesh automati- 
cally prevents the formation of air pockets between the plies. This 
fabric has considerable tensile strength and can easily stretch, with- 
out tearing, over ordinary cracks. This allows the bitumen to heal 
on favorable occasions. There is also somewhat more bitumen 
present in this membrane than is ordinarily present in a felt mem- 
brane of an equal number of plies. Tests by the author have proven 
that jute fabric can be thoroughly saturated and coated with either 
asphalt or coal-tar pitch, and when so treated is well preserved 
against decay. It is from 50 to 100 per cent more expensive than 
treated felt. 

On some construction work raw burlap has been used (that is, 
burlap not treated), but such practice is open to the following 
objections: The hot bituminous binder applied to it in the field 
cannot properly saturate it, neither is the workmanship in the field 
always conducive towards such accomplishment, if that were at all 


possible. And without proper treatment, the jute fabric will be 
comparatively short-lived, especially if exposed in the earth with 
insufficient binder; but this is equally true of the felts and cotton 

The use of treated cotton drill is undoubtedly very good for 
membrane waterproofing, especially if it is strong and well-treated. 
In fact, its use is only prohibitive on account of its relatively high 
cost when compared with either treated felt or jute fabric, especially 
in view of the fact that the latter is not less efficient in any regard. 
All are vegetable products and therefore require equally thorough 
saturation. The cost of the cotton drill, which is at least double 
that of jute fabric and quadruple that of treated felt, also because a 
more or less laminated sheet rather than a reinforced unit membrane 
is formed, especially with the, ordinary variety of close-woven 
cotton fabric, suggests that it be given preference only after careful 
economic consideration. Saturated cotton drill has been used quite 
extensively on the Boston subways, and, except for some few leaks 
that have developed, has given reasonable satisfaction. The very 
best and most efficient type of membrane is one composed of treated 
fabric, with small (in size and number) open mesh, united with a 
uniformly thick bituminous binder. However, for ordinary purposes 
and for rigid structures, felt is entirely serviceable. 

Storing and Unrolling Felt and Fabric. All waterproofing mate- 
rials are injured by improper storage and usage, particularly the 
felts and fabrics. Fabric and felt are delivered on the work in rolls 
usually wound on wooden cores (for types of cores see Fig. 82), from 
100 to 150 yards in length and in varying widths from 32 to 50 
inches, the 42-inch fabric and 36-inch felt being most common. The 
rolls should be stored in a dry place, and in warm weather the fabric 
rolls must not be stood on ends. The most satisfactory way is to 
pile the rolls not more than 2 or 3 feet high, so as to insure uniform 
bearing along their length, and never to pile them criss-cross. As 
it is possible to wind felt much tighter than fabric rolls, they may be 
stored lying down or standing up. In all cases, both materials 
should be protected from the weather and from heat at all times. 

Due to improper storing, fabric rolls become distorted and other- 
wise injured, and are therefore often difficult to unwind, resulting 
in tearing the fabric. Distortion is a defect which tends to create 
" waves," which persist when the roll is unwound and tend to 
occlude air in the membrane. Torn or badly wrinkled fabric should 
not be used. The surface on which the felt or fabric is unrolled 
preparatory to its use in the membrane should be clean. 


Precautions When Heating Coal-tar Pitch and Asphalt. Where 

coal-tar pitch is used as the binder for membrane waterproofing, it 
should be heated gradually up to the proper consistency for applica- 
tion. This is usually at a temperature between 250 and 350 deg. 
Fahr. (121 and 149 deg. Cent.) for a coal-tar pitch with a melting- 
point between 115 and 125 deg. Fahr. (46 and 51.6 deg. Cent.). 
Where asphalt is used, it too should be heated gradually, but its 
working temperature is higher, hence it may be heated to a tem- 
perature between 300 and 350 deg. Fahr. (149 and 177 deg. Cent.). 
Having reached the proper temperatures, the fire should be banked. 
Heating a 50-gallon kettle full of coal-tar pitch or asphalt to the 
required temperature for application, by means of a wood fire, 
should take not less than three to four hours, for the pitch, while in 
the case of asphalt heat may be applied more rapidly, but should 
take not less than two to three hours. A more violent heating in 
either case destroys these materials, especially the coal-tar pitch. 

The danger of overheating, burning or coking (particularly the 
pitch) is constantly present, and cannot be too strongly guarded 
against. One way to prevent overheating is to stir the pitch occa- 
sionally during the melting process, and frequently after it has melted 
until it is all used. Overheating is preceded by the rising of excessive 
fumes of a light bluish tinge. Burning is indicated by the rising of 
yellow fumes from the surface of the pitch. The odor or cackling 
sound is not an indication of the condition of the bitumen. Neither 
is the practice of sticking a piece of wood into the molten bitumen a 
real indication of its degree of heat or of its condition. Coking the 
pitch is indicated by the formation of a more or less thin crust or 
coating on the bottom and sides of the melting kettle. 

When by accident or otherwise the pitch is slightly burned, 
new pitch should be mixed with it before using, and, if badly burned, 
the pitch should not be used at all. It is very essential to the " life " 
of the pitch not to subject it to prolonged heating, even at a low 
temperature, as this drives off some of the volatile oils which are a 
valuable constituent of the pitch. The best practice is to heat 
only sufficient material for one day's use. 

Asphalt, though not as readily affected by heat as coal-tar pitch, 
also requires in its use the observance of the above rules. The burnt 
condition becomes manifest by the rise of blue fumes from the sur- 
face of the asphalt, and when this happens, the fire should immediately 
be extinguished, and additional asphalt put into the kettle. If 
the heat has been excessive and protracted, and if the blue fumes 
have been excessive and constant for more than an hour, the asphalt 


should not be used, because it will undoubtedly have changed or 
lost some of its properties. The effects of prolonged heating are 
inversely proportional to the natural hardness of the bitumen. 

Precautions should always be taken against fire in the heating 
kettles, and if one starts water must not be used to extinguish it. 
As the temperature of the pitch or asphalt during use is far above 
the boiling-point of water, the result of throwing on water may be 
serious. Fires may best be put out by the use of sand or steam. 
As pitch and asphalt hold heat for a considerable time, the workmen 
should be warned of the danger of being burned by these materials. 

Whenever it becomes necessary to transport bitumen, as when the 
particular waterproofing job is beyond a 500-foot radius from the 
location of the heating kettles (which is quite common on large 
construction work), small portable kettles are used for transporting 
the pitch or asphalt. The same precautions must be taken to avoid 
burning and coking the bitumen in these kettles as was previously 
explained for the stationary heating kettles. Where the bitumen 
is carried in buckets, it is best not to allow these to stand more than a 
few minutes before using, as the temperature falls rapidly and the 
material thickens. This condition prevents uniform spreading 
when the bitumen is mopped on the felt or fabric in making the 

Proper Use of Kettles and Fuel when Heating Pitch or Asphalt. 
Coal-tar pitch and asphalt have no serviceable affinity in water- 
proofing by the membrane or sheet-mastic systems. Their mixture 
produces a product which resembles putty in some of its physical 
properties, except when the amount present of one or the other 
does not exceed 5 per cent. Hence the heating kettles should not 
be alternated; i.e., kettles used for melting pitch should not be used 
for melting asphalt or making mastic, and vice versa. Where kettles 
must so be used, it is necessary to clean them, especially where either 
material has caked on the sides and bottom of the kettles, as often 
happens. In fact it is good practice to thoroughly clean the heating 
and mastic-mixing kettles, portable kettles and pails not less than 
once a week even though their use was intermittent. Kettles 
encrusted with bitumen or mastic require more fuel and time for 
heating the contents. The life of the kettle is also reduced by 
the presence of caked bitumen or mastic. 

The easiest obtainable and cheapest fuel for heating kettles is 
discarded construction timber. Staves of asphalt or pitch barrels 
are objectionable on account of the unbearable volumes of smoke 
they produce. Much trouble and a public nuisance would be avoided 


if there was a law prohibiting their use in city streets. Cord wood 
is the best to use, because with it a smouldering fire may be main- 
tained for a long time. This keeps the bituminous material hot 
without burning it. 

Differentiating between Coal-tar Pitch and Asphalt in the Field. 
Engineers unfamiliar with bitumen find it difficult to distinguish 
between coal-tar pitch and asphalt, consequently, mistakes some- 
times occur by using one for the other. Asphalt may be a product 
of asphaltic petroleum, a refined natural asphalt or a mixture of 
both. Coal-tar pitch is a product of the destructive distillation 
of coal in the manufacture of coke or illuminating gas. The follow- 
ing characteristics will aid in identifying each on the work. Asphalt, 
when newly cut, is a bright, lustrous black. It has a pungent and 
somewhat rancid odor and taste. With the application of heat of 
equal intensity, it requires longer heating than coal-tar pitch to be 
brought to the same liquid condition or equal temperature. When 
asphalt burns without flame its fumes are decidedly blue. Coal- 
tar pitch, when newly cut, is somewhat of a dull black and more 
brittle, as compared to asphalt. It has an aromatic taste and odor, 
which is characteristic of pitch only. When coal-tar pitch burns 
without flame, its fumes are a dense, greenish yellow. The safest 
and most advisable thing to do where both materials are used on 
the same work is to require the manufacturers to mark or label the 
containers, so as to make identification easy and certain. 

Coal-tar Pitch Versus Asphalt for Waterproofing. Whether 
asphalt or coal-tar pitch is to be preferred for membrane water- 
proofing is still a mooted question. No doubt, for certain special 
uses, as for instance, where the temperature varies widely, the 
asphalt is a preferable material because it remains soft and workable 
through wide temperature ranges; if the temperature varies but 
little, as it often does in underground work, straight-run coal-tar 
pitch will give better results on account of its greater chemical 
stability. But on general construction work, a good quality of 
either material is equally serviceable, the prevalent contrary view 
among engineers notwithstanding. The author's experience has led 
him to the conclusion that certain brands of asphalt now on the 
market are even to be preferred to some grades of pitch, for this 
reason: The asphalts (all too few, though) as now refined, have 
been constantly improving in quality, while coal-tar pitch did not 
keep pace. In fact, in the last decade or so, on account of the 
increasing value and importance of the by-products from coal tar, 
and, due to the keen competition in the waterproofing field, the 


quality of pitch has materially suffered. Where the quality of 
pitch or asphalt can be controlled or ascertained and verified, how- 
ever, their preference for waterproofing purposes, assuming the con- 
sistency to be right for the climate or local requirement, becomes a 
question of cost. The heretofore superiority of pitch was due to the 
fact that asphalt was often produced as a by-product in oil refineries. 
Now the practice is being reversed, hence the improved quality of 
asphalt now available. But of course, good straight-run coal- 
tar pitch is also available. The point to remember is that both 
materials, if of good and certified quality, are practically equally 
serviceable, with the exception noted above with regard to 


Definition, Purpose and Development. The mastic system of 
waterproofing consists of (1) the application of sheet mastic (com- 
posed of asphalt or coal-tar pitch, sand, grit and cement or stone 
dust), in the form of a comparatively thin layer, which more or less 
surrounds the structure to be waterproofed; (2) a brick-in-mastic 
or tile-in-mastic layer composed of a course or two of bricks or tile, 
the joints being filled and all faces covered with a bituminous mastic, 
the course or courses covering the structure below ground- water level. 

The sheet mastic varies between J inch and 2 inches in thickness; 
the brick-in-mastic varies between 2\ inches and 8 inches in thick- 
ness. The brick-in-mastic layer, being between five and eight times 
as thick as a 3- or 6-ply membrane, and from four to five times as 
thick as the sheet mastic, is usually used where great water pressure 
exists. It is the most dependable system of waterproofing, though 
also the most expensive. In underground construction where head- 
room is a factor, or in general where insufficient space exists for the 
application of one or two courses of brick-in-mastic, and where 
sheet mastic cannot be used, as for instance, on sidewalls of subsur- 
face structures a fabric membrane of from 4 to 8 plies is usually sub- 
stituted. A felt membrane of an equal number of plies should be 
used only when reinforced with 1 ply of fabric for at least each 3 plies 
of felt. This precaution is not necessary, however, on very rigid 
structures, or where expansion joints properly distributed in the 
structure, are provided. 

Almost simultaneously with the development of the fabric 
membrane went the development of the sheet mastic and the brick- 
in-mastic layers. Originally, a coating of mastic (composed of rock 


asphalt, fluxed to the proper consistency) between \ and \\ inches 
thick, was used mainly on horizontal surfaces.* In an effort to 
increase the depth and weight of this coating for waterproofing 
purposes, both on horizontal and against vertical surfaces, bricks 
or tiles were introduced between thinner layers of mastic. Finally, 
even the brick joints were rilled with mastic, resulting in the present 
day brick-in-mastic layer or envelope. Where this scheme is used 
for waterproofing, the materials are always incased between concrete 
or other masonry surfaces. 

Applying Mastic Waterproofing. Sheet mastic for waterproofing 
is mostly used on railroad bridges though it has been employed on 
underground construction. It is most extensively used as a water- 
proof floor for buildings and railroad stations. Sheet mastic is, 
however, subject to abuse in its manufacture and application. For 
instance, the quantities of the various mineral ingredients might be 
poorly proportioned, resulting in a mastic that is too soft or too 
hard; the quantity of bitumen might be insufficient to give good 
cohesiveness and elasticity to the mastic. The sheet mastic might 
be applied without sufficient precautions to prevent cracks produced 
by movement due to temperature changes especially over large 
areas. While the particular purpose in hand should always be 
considered in proportioning of the ingredients for making sheet 
mastic, still the following general directions should be adhered 
to: the bitumen and the sand should each be not less than 10 per 
cent of the finished mastic; the fine mineral dust, whether limestone 
dust or cement, should be not less than 45 per cent, and the grit 
not more than 30 per cent of the finished mastic; the remaining 5 
per cent is sufficient, if carefully apportioned, to take care of any 
special requirements of the mastic. 

When serving only as a waterproofing medium, sheet mastic 
must be continuous over the surface to which it is applied, but its 
abutting extremities must not be relied on to make a watertight 
connection with steel or concrete without special provision being 
made to obtain such a condition. This may be accomplished by a 
cove finish of the ends or by the use of an adhesive, plastic joint filler. 
Often sheet mastic is used in conjunction with other systems of water- 
proofing as, for example, to cover a felt or fabric membrane. With 
due precautions in its application, sheet mastic constitutes a good 

* The use of sheet mastic (or sheet asphalt as it is popularly called) dates back 
to 1838, when it was used to make sidewalks in Paris. It was made of a bitu- 
minous limestone from Seyssel and Valde Travers, and since then nearly all 
European asphalt paving has been done with this asphaltic limestone. 


waterproofing medium, comparable to the brick-in-mastic system. 
Sheet mastic can be made to withstand shock and vibration without 
cracking by introducing a wire mesh or cloth reinforcement between 
equal thicknesses of mastic forming the layer. It is much cheaper 
than brick-in-mastic, but is not as generally applicable. 

Compared to felt or fabric membranes, the use of brick-in-mastic 
to waterproof a structure is more costly, and its application often 
more difficult and more exacting. The reason for this is that the 
amount of labor necessary for preparing the mastic and laying the 
courses to form the envelope about the structure is considerably more, 
as also the quantity of material required for equal areas to be cov- 
ered, than the bituminous membrane. Figs. 19 and 20 illustrate 
some of the difficulties contended with in the application of brick- 
in-mastic to an underground structure, such as a subway. The 
section in Fig. 18, representative of the construction of the new 
Dual Subway in New York City, shows a typical arrangement of the 
waterproofing used on this work. The brick-in-mastic, by its sub- 
stantial nature, protects the floor from percolation due to pressure, 
and the bituminous membrane protects the roof from seepage of 
ground water. 

The condition of a structure to be waterproofed is not always 
what it should be to receive the envelope of brick-in-mastic, hence 
the structure must be made adaptable by artificial means such as 
smoothing, drying, cleaning, etc. It may not be feasible to wait 
until the concrete dries before applying the bri3k-in-mastic, or the 
weather may make it difficult to obtain a dry surface. Where a 
wet or damp surface is unavoidable, a ply of felt or fabric or a mem- 
brane consisting of the two CD nbined should be placed thereon and 
its surface mopped with asphalt if asphalt mastic is being used, or 
with coal-tar pitch is pitch mastic is used. Pools of water and a 
decidedly wet concrete should first be made reasonably dry by suit- 
able means before this dry ply is laid. But no dependence for water- 
proofing is to be placed on any form of dry ply. 

The waterproofing mastic is usually brought to the place of 
application in portable fire kettles or small pouring pails. The 
mastic should not be allowed to stand in these for more than a few 
minutes before using. Failure to observe this results in a loss of heat 
and uniformity of mixture due to the quick settling of the mineral 
aggregate. In any case the mastic should be well stirred before 
pouring it on the prepared surface. The carrying pails must be 
scraped after each pouring to avoid caking of the mastic on the 
bottom by continued settlement. The mastic should always be 



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spread out to a uniform and reasonably thick film (about J inch) 
before laying the bricks therein. 

The bricks, whose function is to give a substantial and thick 
waterproofing layer, are laid in the mastic so as to be completely 
surrounded by a film not less than f-inch thick. In no case should 
brick touch brick. A simple method of obtaining good and com- 
pletely filled joints around the bricks is to slide each brick into place, 
somewhat diagonally and with a slight pressure downward. This 
will invariably bring the bed mastic up into the joints. Spalls 
should not be used under any circumstances. An effort should be 
made to use whole bricks, and bats but sparingly. In applying 
more than one course of brick-in-mastic it is best to build each 
almost simultaneously, with the lower course not more thaa a few 
feet in advance of the upper. Where two courses are decided on 
(in which the bricks are ordinarily placed on their largest bed) it 
will often be found profitable without materially reducing the-: effi- 
ciency of the envelope to build a one-course envelope, but with the 
bricks laid on the narrow side. Ihis scheme will effect a saving 
of 22 per cent in material alone. 

Each course of bricks is to be covered with mastic so that all 
joints and hollows are filled, making the surface even. When 
spreading the top coat of mastic, care is to be exercised in joining 
successive pourings. This top coat sometimes becomes pitted or 
perforated with numerous pinholes exposing the bricks. This may 
be largely overcome by increasing the amount of the fine mineral 
aggregate or by adding a small amount of asbestos fiber. When 
such a perforated condition is detected in the finished envelope 
it should be resurfaced with the pure bitumen. 

Laying protective concrete should proceed immediately or 
shortly after the surface mastic has cooled. The top or exposed film 
of mastic covering the bricks must be cleaned in a manner similar 
to that previously described for membranes. Where temporary 
construction timber cannot be removed during waterproofing opera- 
tions, these locations must t>e taken care of similarly as described 
under the " Membrane system." The forms placed about post 
holes to prevent the protective concrete from flowing into the same, 
should be made watertight to avoid coating the asphalted bricks 
as it is difficult to remove the set mortar afterwards. In 
pouring the protective concrete on the mastic, it is safest not 
to exceed a drop of 6 feet in height to avoid injuring the top 
coating. The surface of the protective concrete should be troweled 


Precautions when Joining New and Old Brick-in-Mastic. The 

ends of the courses at the finish of each day's work, or when work 
is temporarily discontinued, must be well mopped with asphalt or 
coal-tar pitch, depending on the kind of mastic used, leaving no 
bricks uncoated. To preserve the physical condition of these ends, 
2-inch boards may be laid up against them, especially where resump- 
tion of work may be delayed for a long time. In commencing the 
new work, the old surface should be cleaned and softened so as to 
properly join with the new mastic. The use of a gasoline torch 
or the burning of some gasoline on the surface is sufficient to accom- 
plish this. 

Where temporary braces, posts and other supports are used on the 
work and are not moved to accommodate the brick-in-mastic layers, 
all four sides of such post holes should be stepped when more than 
one course is used (see Fig. 16). In waterproofing these post holes 
after removing the posts, all surfaces are to be carefully cleaned and 
remopped with bitumen. The mastic is then poured on the pre- 
pared area and the bricks embedded therein in the ordinary way. 
It is advisable to dip these bricks in bitumen or mastic before laying. 
In fact, all possible precautions should be taken to secure an absolutely 
watertight joint on all kinds of patch work. 

Placing Mastic around Projections and in Vicinity of Steam 
Pipes. If, through a masonry surface which is to be waterproofed 
by the application of a layer of sheet mastic or brick-in-mastic, such 
objects as pipes or rods project, careful workmanship is required 
to make these locations watertight. Whatever the object be, that 
part of its surface which will be included in the waterproofing layer 
must be cleaned thoroughly. If these objects project through a 
floor or roof, then it is well to leave an open ring about 2 inches wide, 
completely around them, as the course or two of brick-in-mastic 
is laid down. Then this ring space is preferably filled with a mastic 
of softer consistency than that used ordinarily, or with pure asphalt. 
Sheet mastic may be applied without this temporary space around 
projecting objects. If objects project from vertical surfaces, it is 
first of all necessary to make the form (required for placing brick- 
in-mastic against walls) fit snugly around the object. Then the 
bricks should be so laid in the mastic at these projections as to leave 
a space about 1 inch wide around them, to be filled by the mastic. 
A better bond will be secured between the mastic and the pipe, rod, 
or other projecting objects, if these are first swabbed with pure 
bitumen. In some instances, where the importance of the work 
warrants it, the efficiency of these connections will be enhanced 


by the judicious application of waterproofing felt or fabric, as for 
instance, if the joints were made as described under " the membrane 
system"; then, by the further filling of the ring spaces with 
mastic or pure bitumen, more positive joints are secured. 

In the event that steam or hot- water pipes or mains project 
through the masonry, then it is first necessary to insulate them so as 
to reduce the effect of their radiating heat to a minimum. The usual 
method for doing this is also described under " the membrane 

Preparation of Wall Surfaces for Brick-in-Mastic. When exterior 
waterproofing is intended for an underground structure running 
through rock, an effort is made while excavating to leave the natural 
sides as vertical and smooth as possible. But this is never attained. 
Hence a sand wall of concrete is applied against the natural rock to 
supply a vertical and smooth surface. This acts as the " armor- 
coat " for either the membranous or mastic type of waterproofing. 
Excavation in earth requires the customary sheet piling and bracing. 
This sheet piling is generally placed sufficiently outside the neat line 
to permit the building of either a one-course brick or terra-cotta 
hollow-tile wall. This wall then acts as an " armor-coat " for the 
waterproofing. In some instances steel or wooden sheet piling is so 
placed as to preclude the possibility of building a masonry wall within 
its confines, then this piling is made to act as the armor-coat for 
receiving the waterproofing. (Fig. 19.) These conditions, however, 
only occur on large and difficult work where they must be given 
special consideration. 

If the masonry armor-coat against the rock surface or sheet 
piling is too wet to receive the waterproofing, or when the sheet- 
piling armor is in a similar condition, then a so-called dry ply of either 
felt or fabric, or a combination of the two, is first applied. Where 
water is actually running over the face of the wall or sheet piling, 
it should be diverted temporarily. This may be done either by 
inserting sufficient bleeders at the best elevation, or by attaching 
a strip of tin in the shape of a trough above the space to be water- 
proofed. Plaster of Paris or cement may be used for attaching this 
strip. If, by these methods, the surface cannot be made thoroughly 
dry, a dry-ply of felt and fabric combined is to be hung up against 
the surface. The brick-in-mastic is then laid against it in such a 
manner as to permit the water to flow down and progressively forward 
and out from behind this dry ply. Wherever there is no direct water 
to contend against, as above noted, the dry ply may consist of strips 
of felt or fabric, mopped in the usual way. In building the armor- 


coat of concrete, the form for it should be made rigid so as to avoid 
bulging. Neglect of this precaution causes a reduction in the cross- 
section of the brick-in-mastic wall, a condition to be avoided, as 
eventually it may be the cause of leaks, due to the careless practice 

FIG. 19. Showing Partly built Main Wall, 1, and Forms for Brick and Mastic, 2. 
Note Top Row of Bricks Covered with Mastic, and Sheet Piling left in 
Place Acting as Armor for Waterproofing. 

of filling the narrow parts of the forms with small pieces of brick, or 
squeezing in whole bricks and thus thinning the joints. 

Precautions for Setting-up, Filling and Stripping Forms for 
Brick-in-Mastic Walls. In building brick-in-mastic walls, forms 
are necessary mainly to allow the mastic to set, and in warm weather, 
even after. Fig. 19 shows a form for a two-course mastic wall in 



2 Courses 

FIG. 20. Building of Two-course Brick-in-mastic Wall, Showing Form, Form 
Bracing, and Sand Wall. 


course of construction against a sand wall preparatory to the placing 
of the finished wall within. Therefore, after the surface of the 
armor-coat has been properly prepared, the forms should be placed 
the required distance from it. This distance is governed by the 
manner of laying up the bricks; i.e., if the longest edges of the bricks 
are perpendicular to the wall (all bricks being laid as headers) 8J 
inches form space is required; if they are laid parallel to the wall 
in two courses, 8 inches are required, and in single courses, 4 inches. 
Of course this assumes the use of common red brick, as no better 
or special kind is necessary. The height of form sections are not to 
exceed 3 feet, so as to enable the waterproofer to easily reach the 
bottom in laying the bricks. In bulkheading the forms, tight 
joints are necessary. 

To insure the easy and successful stripping of forms, the inner 
surfaces of the forms are to receive a wash coat of neat cement, or 
have a strip of felt attached. Washes of lime or clay may also be 
used to good advantage, but in no case should lumpy clay be 
applied. Any of these coatings are best applied before the forms 
are set up. 

When the forms are erected, a pail of mastic is poured and spread 
uniformly therein. The bricks are immediately embedded in the 
mastic, usually on their largest bed and with their longest edge 
parallel to the wall. In laying the brick no mastic should be allowed 
to collect or extend beyond any course of bricks. In laying the 
successive courses of brick, they may be made to break joints in the 
same manner as in a brick and mortar wall, but this is not essential. 
Where the space between the wall and the form is not wide enough 
to allow one or two bricks as the case may be to be laid on their 
largest bed and with proper joints (in the manner described above) 
due to bulging of the sand wall or armor-coat, the bricks should be 
laid so as to leave more mastic in the joints and faces. Sometimes 
a ply of fabric is added for each inch of reduction of form width 
due to this bulging, but this is inadequate and should be guarded 

Settlement and Bracing of Brick-in-Mastic Walls. Where the 
mastic forms must be removed prior to the building of the main 
wall, the mastic wall should be well braced to prevent buckling and 
undue settling. In warm weather the removal of mastic forms should 
be done only shortly before building the main wall. Where failure 
to observe this rule has caused any decided deformation in the mastic 
wall, this portion should be cut out and properly replaced with new 
materials. But quite often it will be possible to push the bulge back 


into place by applying a constant force, pressing on as large an area 
of the bulge as possible. 

All asphalt mastic on cooling will reduce in volume and settle, 
(about | inch in a height of 10 feet per 30 deg. Fahr. (16.5 deg. Cent.) 
change in temperature for a 2 : 1 : 1 mastic) therefore no concrete 
should be placed on top of a mastic wall until complete cooling and 
settlement has taken place in it. Neither should a mastic wall be 
counted on to carry any weight at any time because it cannot per- 
form this function by the very nature of its make-up. On extended 
flat surfaces, however, it can be made to safely carry about 300 pounds 
per square inch at about 60 deg. Fahr. (15.5 deg. Cent.) if movement 
in the layers is impossible. 

Where a mastic wall is to join the brick-in-mastic on the roof of a 
structure, it should be brought up to the level of the roof-masonry, 
and allowed to settle and cool, then the mastic on the roof should be 
laid and joined to the wall mastic. The protective concrete or other 
masonry is then laid so that its joints are not directly over the joints 
in the mastic waterproofing. 

Materials for Making Mastic : their Properties and Proportions. 
Asphalt or coal-tar pitch may be used for making mastic. Both must 
be carefully selected and tested to insure their adaptability. The 
usual practice is to use a minimum of 33 per cent of bitumen, but this 
may be decreased to 25 per cent where a stiff mastic is required, or 
increased to 50 per cent where a less viscous mastic is desired. The 
mineral aggregate, the presence of which tends to increase the tensile 
strength of the binder, is usually sand, cement or limestone dust, 
and sometimes asbestos fiber is added as a filler. The proportions 
are often arbitrarily and carelessly specified. The aim in this regard 
should be to proportion the mineral filler to produce maximum den- 
sity which insures maximum strength. 

The sand for making mastic should all pass through a 10-mesh 
sieve. It should never be used when wet or moist, and in general, 
should be heated before using. (Figs. 77 and 78 show the customary 
ways of doing this.) This will lessen the formation of bubbles and 
pin holes in the mastic caused by the escape of the occluded moisture. 
The sand should also be clean, free from dirt, silt, or vegetable 

Any cement in good condition is suitable for making water- 
proofing mastic. Fineness of the material is the important factor, 
because the finer the grain, the more intimate is its incorporation 
with the bitumen. The limestone dust need not be as fine as the 
cement, but it should pass at least 80 per cent through a 100-mesh 


sieve, and 10 per cent through a 200-mesh sieve. Slate dust is 
sometimes substituted, but it usually lacks the fineness of either 
cement or limestone dust. 

Bricks used for brick-in-mastic waterproofing should be of good 
quality common brick, burned hard entirely through, regular and 
uniform in shape and size and of compact texture. They should 
also be heated to complete dryness before using, and so heated as to 
remain practically clean, i.e., free of excessive soot. The various 
methods for doing this are discussed below. 

The two-thirds mineral aggregate referred to above may consist 
of a mixture of sand and cement or sand and limestone dust with a 
reasonable amount (not more than 1.5 per cent), in either case, of 
asbestos fiber. The latter material, however, may be dispensed with, 
as it is only necessary in special cases, as, for instance, on the top 
or final coating of the mastic layer when this is located a few feet 
below ground surface. The sand and cement is usually mixed in 
equal proportions by weight or volume, but it would be much 
better to mix these with due regard to the percentage of voids in 
the sand. In the rare instances where mastic is to be laid in a very 
wet location, more mineral matter should be used, as this will 
increase the weight of the mastic and decrease the tendency to create 
bubbles in the asphalt due to the steaming and upward pressure of 
the water, also when it is to be used on an incline, as more sand 
stiffens the mastic. In the mastic that is used as a top coating for 
the upper course of bricks, less sand should be used. This will 
leave the mastic more ductile and plastic, permitting it, if cracked, 
to heal more readily when the temperature is suitable An addition 
of asbestos fiber may be made instead of reducing the sand, as this 
also gives a more flexible coating. 

Hand- versus Machine-made Mastic. When making water- 
proofing mastic by hand, it is important to see that the sand and 
limestone dust are thoroughly dry. The sand and cement or lime- 
stone dust are first mixed in proper proportions and then put into 
the mixing kettle after sufficient asphalt has been melted therein. 
The temperature of the asphalt mastic should be kept between 350 
and 400 deg. Fahr. (177 and 204 deg. Cent.) and coal-tar pitch mastic 
between 275 and 325 deg. Fahr. (135 and 163 deg. Cent.). The 
aggregate should not be dumped into the melted asphalt but sprinkled 
into it. Stirring the mastic must be continued until a uniform mix- 
ture has been obtained. This requires at least twenty minutes of 
continued stirring for a 50-gallon kettle. 

On large work a battery of mixing kettles is usually centrally 


located, but where the particular waterproofing jobs are beyond a 
500-foot radius from the mixing kettles, the mastic must be trans- 
ported in portable fire kettles. The mastic in the mixing kettles 
is to be stirred before pouring into the portable kettles, and when it 
arrives at the place of waterproofing, the mastic should again be 
stirred before pouring into the carrying pails. No mastic from the 
hot portable kettles must be poured into the carrying pails unless 
it is to be used immediately, otherwise settlement of the aggregate 
results and the uniformity of the mixture is destroyed. 

The practice of making mastic by hand in open fire-heated kettles 
is as old as the mastic industry, which began between 1880 and 1885. 
But, though paving mastic has for many years been made by machine, 
floor and waterproofing mastic continue to be made by hand. This 
is partly due to the fact that (1) heretofore such mastic was not a 
commonly used material, (2) natural rock asphalt was mostly used 
in the belief that an artificial mastic was impossible or very inferior, 
(3) the secretiveness with which the mastic industry was developed,* 
and (4) the comparatively small quantities of floor mastic generally 
called for on any particular job. 

Making reasonably good mastic by hand is of course possible. 
But there are many drawbacks not usually considered. For instance; 
the consistency of the mastic is usually determined by the operator 
and hence no two batches are alike; neither are the proportions of 
ingredients constant, for they are usually dumped in by "eye"; 
then, what is worst of all, the man mixing the mastic naturally 
desires to lighten his labor and occasionally either does not suffi- 
ciently mix the batch, or adds more bitumen than the amount 
specified. All of these objections would be absent in a machine- 
made mastic, because the ingredients would necessarily have to 
be weighed or measured, as is done in mixing concrete by machine. 
The quality would also be easily regulated and the engineer could 
better inspect the work to see that his specifications were lived-up to, 
especially in the matter of cooking the mastic. On large work this 
is very important. 

A type of mastic-mixing machine which makes this possible, 
and indeed, makes a superior mastic, is shown in Fig. 67. The 
author, who has experimented with and observed the product of a 
machine of this type for a long time, can state confidently that it 
would be to the interest of the mastic industry to abolish the hand- 
mixed product and resort to a machine-mixed mastic, especially 

:2l ln the early days of the mastic industry it was not beneath some of those 
engaged in it to employ the tricks of witchcraft to fool the inquisitive. 


because of its economy. This economy results from the fact that 
the asphalt does not have to be first melted and heated as with the 
use of open kettles, and also because none of the mineral aggregates 
needs preheating. This is all accomplished in the drum of the 
machine, which, besides, can mix a much larger batch in considerably 
less time than men can mix it in open kettles. Machine-mixed 
mastic is, however, admittedly impracticable on small jobs, and has 
not yet been used for making waterproofing mastic such as described 
above, that is, its use heretofore has been limited to floor and paving 

Brick-heating Methods. In the use of bricks for brick-in-mastic, 
the question often arises as to (a) when the bricks should be heated, 
(6) to what extent they should be heated, and (c) by what method 
they should be heated. In answering these questions experience 
is the best guide. Bricks used as above noted should be heated (a) 
when the temperature is below 40 deg. Fahr. (4.5 deg Cent.), (6) 
when they are moist or damp (because either condition prevents 
good bonding between the bricks and the mastic) , (c) they should be 
heated to a degree not exceeding that which permits their being 
handled with the bare hands (because otherwise the mastic film 
surrounding the bricks will be melted off), and (d) the method of 
heating should be such as will not cover the bricks with an over 
amount of soot, because this tends to prevent proper bonding, and 
bonding is very essential to the continuity of the layer or envelope 
of brick-in-mastic. 

A method of heating bricks to be strictly avoided is the following: 
A small make-shift furnace, constructed by enclosing three sides of a 
convenient area with walls of either brick or stone, laid dry. These 
walls are of any convenient length and about a foot high ; the fourth 
side remains open and through it the fire is fed. On top of the walls 
is placed a wire screen strong enough to support about 200 or 300 
bricks piled promiscuously. A wood fire is kindled underneath 
and the heat and smoke pass up between the bricks. This method 
not only fails to heat the bricks alike but also covers them with more 
or less soot, and is slow and wasteful. 

A better method is the following: A hollow cylinder about 
4 or 5 feet in diameter is made by piling bricks one upon the other 
with loose joints, but interlocked so as to make the entire cylinder 
self-supporting. The bricks are laid on their largest bed and built 
up to a convenient height, say 3 or 4 feet. Next, a wood fire 
is made within the cylinder, or, better still, a coke fire is main- 
tained in a salamander placed within the cylinder. If a wood 


fire is used the flames should be kept low. This scheme permits 
the escape of smoke without covering the bricks with soot. The 
radiating heat dries the bricks to any desired degree depending 
on how long they remain near the fire. If a second row of bricks is 
built around the first one it will receive its incipient heat and as the 
inner cylinder of bricks is used up the outer one will gradually receive 
its share of heat. This method, however, is also slow. A mechani- 
cal brick heater is described in Chapter VI, and is the most efficient 
means for heating and drying bricks known to the author. 

Weather Conditions Governing Waterproofing Operations. To 
obtain the best results, no waterproofing should be done wherein 
ordinary bitumen is used as the cementing or binding material, 
especially in the form of a membrane, sheet mastic, or brick-in- 
mastic layers, when the air temperature is below 40 deg. Fahr. 
(4.5 deg. Cent.), nor during snow, rain, or drizzle. Coal-tar pitch 
chills rapidly in cold weather and will not stick well to cold masonry; 
and asphalt is even less adhesive to cold masonry. Neither pitch 
nor asphalt will adhere to a wet surface, therefore these conditions 
must be avoided. However, if the work be amply protected from 
cold and wet weather, waterproofing may proceed with due precau- 
tions for eliminating the hazards of these conditions. On the other 
hand, in warm weather, care must be taken to protect the finished 
waterproofing promptly, especially if it is exposed to the sun, other- 
wise expensive repairs may become necessary, before or soon after 
completion of the work. 


Definition, Purpose and Development. The integral system of 
waterproofing is the process of making impermeable mortar or con- 
crete by incorporating in the mass, certain ingredients which act 
either as void fillers, as lubricants for the aggregate, or chemically 
upon the cement, thus densifying the mass. These ingredients con- 
sist of (1) finely ground powders, such as clays, silicates, feldspars 
and hydrated lime, which are usually mixed with the dry cement 
at the mill or on the work; (2) liquids and pastes such as stearate of 
lime (water-insoluble soap), sodium or potassium oleate (water- 
soluble soap), aluminum stearate, calcium chloride and oil com- 
pounds, which are usually mixed with the gaging water, though 
they are sometimes added to the mixed mass to form an integral 
part of the resulting mortar or concrete. 

The fillers may be inert or active. If inert, as the above powders 


are, they merely fill up the pores or voids inherent in the concrete, 
but if active, as the above soap compounds are, they may either 
unite with the cement or crystallize in themselves. The resulting 
compounds tend either to fill the voids and barricade the pores or to 
become water repellent. Most of the liquids and some of the pow- 
ders are inactive lubricants of a fatty nature, and these assist the 
aggregates to slide more compactly into place. 

The purpose of the integral system of waterproofing is to make 
concrete and mortar impermeable by the application of the water- 
proofing materials during the process of mixing, thus reducing the 
cost of the construction by eliminating the necessity for any addi- 
tional treatment. This system of waterproofing, however, does not 
remove the need for thorough mixing and careful placing of the 

The integral system of waterproofing is best adapted for treat- 
ment of structures in the course of construction, principally of the 
type not subject to vibration or shock. For water tanks, dams, 
foundations, and other stationary or rigid concrete structures, where 
absorption or percolation through the concrete may work serious 
havoc, it is particularly well adapted. However, the possibilities of 
making mass concrete impermeable by the simple expedient of care- 
fully grading and correctly proportioning the aggregate and pro- 
longing the time of mixing should not be forgotten. For railroad 
subways and bridge floors, this system should not be specified, no 
matter how promising may be the materials offered; for, even if the 
waterproofing materials added do not weaken the concrete (as 
sometimes happens when inferior compounds are used), they cannot 
prevent its cracking under vibration of traffic and the consequent 
percolation of water through such cracks. 

The incorporation of foreign ingredients in mass concrete to 
increase its density, or, what amounts to the same thing, decrease 
its permeability, is not so very old. Originally quick lime was used, 
then certain patented compounds began to appear on the market, 
such as stearates and resinates (water-insoluble substances), and 
finally hydrated lime began to be used for this purpose. In recent 
times numerous secret and patented compounds have been exten- 
sively used, but owing to a general dissatisfaction with the results 
obtained, they have received a considerable setback. And with 
them some very good materials were thrown into disrepute. The 
practice of adding an arbitrary but small percentage of cement 
over and above the calculated amount is quite prevalent, and often 
accomplishes the results claimed for many of these special compounds, 


Limitations of the Integral System of Waterproofing. The use 

of integral waterproofing compounds should be limited to conditions 
where certainty exists regarding character of stresses in the structure, 
and then only after the materials have been analyzed, tested and 
proven efficient. The following pertinent remarks by the U. S. 
Bureau of Standards* corrobate the foregoing: " The addition of 
so-called integral waterproofing compounds will not compensate 
for lean mixtures nor for poor materials, nor for poor workmanship 
in the fabrication of the concrete. Since in practice the inert 
integral compounds (acting simply as a void-filling material) are 
added in such small quantities they have very little or no effect 
on the impermeability of the concrete. If the same care be taken 
in making the concrete impermeable without the addition of water- 
proofing material, as is ordinarily taken when waterproofing materials 
are added, an impermeable concrete can be attained." 

The incorporation of any kind of integral waterproofing material 
into a mass of concrete will not materially prevent the formation of 
hair cracks or temperature cracks or cracking due to uneven settle- 
ment. Results with different materials will vary, but very few 
have proven entirely satisfactory. Neither can this system prevent 
seepage through day's work planes, and expansion joints, or joints 
between steel and concrete. Furthermore, this system of water- 
proofing, or rather the materials used in connection therewith, may 
reduce the strength of concrete and sometimes may even induce 
disintegration in the concrete. The integral waterproofing materials 
that will not do these things are, in fact, few, and their successful 
use requires so much care and labor that better results may often 
be obtained by the self-densified system of waterproofing, f In the 
light of present-day knowledge and experience with integral water- 
proofing compounds, their use and need are debatable on the basis 
of real efficiency. There are many cases, nevertheless, where any 
other system of waterproofing as well as the integral system might 
be used with equally good results, the selection under such cir- 
cumstances, being, of course, a comparison of costs. The integral 
system has, however an advantage always worthy of consideration, 

* Technologic Paper No. 3, p. 83. 

fThe author is able to say that several manufacturers of integral water- 
proofing materials have admitted this to him, but they asserted that these 
materials are worth their cost merely by acting as a factor of safety. It seems 
more probable, however, that these materials act more psychologically than as a 
safety factor. That is to say, workmen will probably feel more inclined to 
prolong the mixing and tamp more vigorously when told or shown that some- 
thing has been added, but which will really be effective only by such activity. 


namely, it requires no additional excavation or protective masonry, 
and the waterproofing operation proceeds with the construction, 
which is often a great advantage. In justice to some materials of this 
type that have apparently given satisfaction, it must be admitted 
that there is really great need for more extensive, and exhaustive 
practical tests, that is service tests, on this entire class of materials. 


The types of materials above mentioned namely, po*wders, 
pastes and liquids, will now be considered in a more detailed manner. 
The many integral compounds appearing on the market are mostly 
of a water-repellent nature, but their compositions are seldom 
divulged, except those which are patented. The powders are usually 
of a white, floury consistency, and water-repellent. This property 
is imparted to them by the addition of some metallic stearate such as 
limesoap, which is of a fatty nature. The fineness of the powders 
gives them their void-filling properties, while those of a fatty nature 
act also as a lubricant for bringing into closer proximity the con- 
stituent materials of the concrete. The addition to the concrete 
mass of various amounts of hydrated lime also creates a dense mixture 
by the same procress. 

Use of Hydrated Lime. In regard to the addition of hydrated 
lime, experience has demonstrated that it serves to increase the 
plasticity and also to lubricate, as it were, the aggregate of the con- 
crete, resulting in a denser and more uniform mass. But the United 
States Bureau of Standards* states that the value of hydrated lime 
as a waterproofing medium is probably due to its void-filling prop- 
erties, and that the same results could be expected from any other 
finely ground inert material, such as sand or clay. While this is 
true, it is none the less an indisputable fact that hydrated lime acts 
in a greater measure as a lubricant, which the others would only do 
in a very limited way. Many proprietary compounds are composed 
mainly of finely ground sand and clay. 

By adding from 10 to 15 per cent of hydrated lime, the tendency 
of concrete to check and hair crack is materially reduced, as the 
lime absorbs and retains a large percentage of water and therefore 
holds the moisture in freshly poured concrete until the slower acting 
cement can utilize it. 

Mr. Sanford E. Thompson,! in a series of experiments on the 

* Technologic Paper No. 3. 

t American Society for Testing Materials, June, 1908. 



effects of hydrated lime in concrete, arrived at the figures in Table 
IV in regard to the effective proportions of hydrated lime for pro- 
ducing water-tight concrete. 






(Per Cent). 













The percentage of lime is in terms of weight of cement. The 
sand and stone are representative of average materials throughout 
the country. The coarser the sand, however, the more lime should 
be used. 

Lime paste occupies more than two times the bulk of paste made 
from an equal weight of Portland cement. Hence, by replacing 
the cement in mortar by about 15 per cent of hydrated lime, 
its density, and in consequence its strength and permeability are 

But even with the addition of hydrated lime, the concrete 
materials must be graded, and 'the proper proportions of cement and 
hydrated lime used. If the concrete is poorly mixed or made with 
insufficient water, or improperly placed, or if joints are left unpro- 
tected, the structure will inevitably leak. The mixing must be 
thorough, sufficient water must be employed to give a " mushy " 
mixture so that it will settle into place with the least amount of 
ramming. Fully as important as the care in mixing is the bonding 
of one day's layer of concrete with the next; even small inter- 
ruptions of an hour on a hot day will materially injure the bond of 
the concrete. 

Use of Inert Fillers. Inert fillers vary greatly in durability and 
resistive properties, and should therefore be selected with con- 
siderable care. A governing property of all inert fillers is that they 
should not only be inert in the presence of the cement but also to 
atmospheric moisture and gases and percolating waters. 

Many fillers now used consist of clay, sand, lime and ordinary 
natural or Portland cement, this latter in a form exceedingly finer 
than ordinarily used, or in the form of " excess quantity " to make 
a rich mixture of the mass of mortar or concrete. 



The chemical composition of some inert powder fillers are given 
in Table V together with a comparative analysis of average Portland 
and natural cements. The first two are taken from a Technologic 
Paper of the United States Bureau of Standards* together with part 
of the following remarks: 

" Those materials which act as void fillers or increase the density 
of the concrete and are without any action on the cement and do not 
themselves change, are known as inert fillers. Included in this class 



N. Y. 






58 30 


64 02 

89 50 

1 34 


16 85 

15 01 

19 38 

2 36 


Ferric oxide 
Manganese oxide 












32 19 

Sulphuric anhydride (SO:.) . 
Sodium oxide 
Potassium oxide 



2 12 

11 76 



15 05f 

Water (105) 





Ignition loss 










* Carbon dioxide. 

t Total water. 

are hydrated dolomitic lime, clays, finely ground sand, and finely 
ground feldspar. Some of these may be partly changed in time 
when in the concrete. The hydrated lime may be partly carbonated, 
especially on the surface; the feldspar may decompose by the 
leaching out of the alkalies; the sand will change but very little, 
if composed of a high-grade quartz sand ; the clays will be very inert, 
although some theories have been brought forward which assume a 
very important role for clay when mixed with concrete ; this is to the 
effect that the colloids of the clay protect the calcium compounds 
from quick hydration, and consequently prevent increase in volume 
due to chemical action." However, reliable data show that the 
addition of clay to concrete or mortar decreases their permeability 
considerably and even increases their strength to a slight degree. 
But the use of clay as balanced against the addition of extra cement 
* Technologic Paper No. 3, p. 44. 


to accomplish the same results should be carefully considered, 
especially in the light of a comparison of costs. For, reasonably good 
clay must be used, and unless cheaply obtained the balance will 
invariably be in favor of the cement. Plain blue brick clay and pure 
white Georgia clay may be used with good results as inert void 

Use of Active Fillers. Active fillers consist of compounds which 
react with certain constituents of the cement, thus forming new 
compounds which are themselves inert and either barricade or fill 
up the voids. In most of these compounds on the market the active 
fillers form, but a small percentage of the compound proper as 
illustrated by the analysis in the first column of Table VI. " This 
compound was a white powder with a strong aromatic odor of 
Kauri resin. It was in fact partly a resinate of potash, which 
would be decomposed by the lime present to the corresponding lime 
rcsinate, which is comparatively insoluble. The great part of the 
compound is entirely inert, being china clay and hydrated lime. 

"As, however, in themselves these materials are not waterproofing, 
but become so only as a result of a series of reactions, it would be 
better to use the result of these reactions directly and not depend 
upon something that may not always take place either wholly or 
in part." 

Use of Proprietary Cements. Some proprietary cements are 
compounds made of Portland cement that has been altered by the 
addition of either stearates of lime, or soda and potash, sand, and 
other materials and specially treated until the mass becomes a water- 
repellent cement. Again, some waterproof cements are made by 
mixing about 5 per cent (by weight) of a lime-oil compound in 
clinker form, with Portland cement clinker and grinding them 
together. The powder formed is then used as ordinary cement, 
and results in a more or less dense concrete, not, however, in- 
dependent of the necessary care in mixing and placing. Another 
form of compound of this nature consists of fish-oil boiled in hydro- 
chloric acid, then mixed with burnt lime while slaking with water, 
the resulting product being a paste which dries and hardens as 
clinker. Another similar compound is made by combining a pow- 
dered resinate compound consisting of copal gum, hydrated lime and 
fine clay in proportion of 1 : 1 : 1 by weight with Portland cement, 
the use of which tends to make waterproof mortar or concrete. These 
compounds are also used for surface coatings as well as direct cements. 
When used as a direct cement, the lime-oil cement compounds depend 
for their impervious tendencies upon the formation of stearates of 





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lime which are practically insoluble in water, and the presence of a 
large amount of hydrated lime, which also acts as a lubricant and 
inert void filler. On the other hand, the stearates of soda and potash 
are ordinary soap, readily soluble in water. With these soaps a 
reaction occurs when they are treated with water in the presence of 
cement; the soda or potash is dissolved and the more insoluble 
lime soaps are precipitated. If this kind of cement is used as a sur- 
face coating, however, it is doubtful whether the above reactions 
take place in a sufficient quantity of the soap to effect proper water- 
proofing properties before it is dissolved and washed off the surface. 
Experience indicates that in general, soap solutions do not bring 
lasting results as a waterproofing agent. Several cements of this 
nature have been analyzed by the United States Bureau of Standards 
with the results shown in Table VII.* 



Compound Used as 
Direct Cement 

Compound Used as 
(Cement Content) 


23 75% 

22 40% 


5 96 

7 98 

Iron oxide 

1 97 

3 63 




IVIajrnesia r 



Sulphuric anhydride (SO ). 

1 21 


Sodium oxide 


Potassium oxide 


Ignition loss 



Carbon dioxide 



fOrcanic (fat acid) 







*This compound consists of Portland cement (27.73%) and sand (72.27%). The sand 
(all passing one-eighth sieve), is mixed with the cement, and is composed of quartzite and 
dolomite; there is also a trace of fat acids present. 

t The organic is fat acids with a melting point of 52 deg. Fahr. and present as a lime soap. 

Use of Integral Liquids. The liquids are mainly composed of 
metallic salts, such as chloride of lime; they also consist of oil 
emulsions and soap solutions, and solutions of paraffin in benzine 
* Technologic Paper No. 3, pp. 41 and 47. 


or benzol. But the paraffin solutions are usually not added to the 
gaging water, these being applied to a masonry surface with a brush 
as explained under the surface-coating system. The waterproofing 
properties of these liquids are derived from the formation of gela- 
tinous coatings around the smallest particles of the constituents 
of the masonry. Of course, this would tend to decrease the strength 
of the concrete, and often does. There is also a coal-tar product 
used as an integral waterproofing from which the volatile oils have 
been almost entirely removed, and the remaining materials tend to 
bind together the particles of cement and fill the voids in the concrete. 
Some other compounds are composed of fish oil and water glass 
(sodium silicate). The fish oil, which is semi-drying, is slowly 
saponified by the lime of the cement, and the water glass forms a 
lime silicate, both actions, however, being incomplete, due to the 
insufficiency of lime present in the cement for such action. Analyses 
of a fish-oil compound and one of calcium chloride follow.* 

Fish-oil Compound. Calcium Chloride Compound. 

Soap 1 .05% Silica trace 

Oil 47 . 29 Alumina and iron oxide . 25% 

Ash water glass 11 . 64 Calcium chloride 27 . 19 

Volatile (water) 40 . 02 Magnesium . 04 

Water (and iron resinate 15%) 72 . 52 

Use of Integral Pastes. Most pastes are soluble mixtures of 
secret ingredients which derive their waterproofing properties by the 
precipitation of insoluble materials in the voids of the concrete. 
Some also act so as to consolidate the mass by increasing its 
plasticity. These contain either fine clay, lime, or colloidal matter, 
or all of these. 

Sometimes pastes are made by mixing a powder, such as alum, to 
the cement, and a soap solution to the tempering water. In making 
the concrete this paste is added, and the two constituents combine 
to form a stearate of aluminum which, as noted before, is a stable, 
water-insoluble, void-filling compound. 

In the employment of integral pastes or any of the above com- 
pounds it is advisable first to investigate the efficacy of the materials 
by inspection of results accomplished on previous work. By sub- 
mitting samples for analysis to qualified chemists, or by sending 
them to the United States Testing Laboratory the following neces- 
sary information can be obtained for a nominal cost: (a) effect on 
the strength of the concrete; (b) waterproofing properties when 
subjected to extreme ranges of temperature; (c) effect of common 
* United States Bureau of Standards, Technologic Paper No. 3, p. 48 


acids and alkalies on their waterproofing properties; (d) effect on 
steel reinforcement, i.e., if productive or preventive of corrosion, etc. 
In all cases the manufacturer's written instructions should be 
followed with due observance, of course, to any special conditions 
arising on the work necessitating variation or change of manipulation. 


Definition, Purpose and Development. The system of water- 
proofing, or, more properly speaking, the practice of making imper- 
meable concrete or mortar by means of self-densification, is, as the 
name implies, a process of proportioning the constituent materials 
and mixing them so as to create as dense a finished mass as possible. 
This is as difficult to obtain as it is finally effective in producing 
watertight concrete. The reason for this difficulty is that the 
requisite density is dependent upon varying factors, the ones most 
frequently militating against density being the lack of interest and 
inevitable fatigue of the labor employed together with the uncer- 
tainty of obtaining the specified quality and exact amount of materials 
for each batch without exceptional precautionary measures. 

The self-densifying system of waterproofing like the integral 
system is adapted to any kind of mortar or concrete structure not 
subject to severe vibration, undue settlement or extreme variations 
in temperature, unless the movements due to such settlement or 
temperature changes are taken care of by properly located and 
waterproofed expansion joints. Its main purpose, however, is to 
eliminate the use of any form of waterproofing, because of the extra 
cost of materials, and the requisite time, labor, and attention neces- 
seary in the application or incorporation of most forms of water- 
proofing compounds. If the energy spent in preparing and applying 
waterproofing materials were expended on careful proportioning, 
mixing, and supervision in making the mass concrete or the mortar, 
the engineer would obtain more nearly impervious masonry. The 
supervision required in either case, to obtain the best results, is in 
fact, about the same. 

The origin of self-densified concrete is probably coincident with 
the origin of making concrete. In attempting to duplicate natural 
stone in strength, it was but one step further to attempt to make the 
concrete as dense as such stone. This probably led to the develop- 
ment of a form of cement so fine in itself as to have practically no 
voids whatsoever. Such a fine-ground cement carries more sand, 
and makes denser and more impervious concrete than the cement 


of the old standard of fineness. This standard of fineness was 5 
per cent passing a 2500-mesh sieve, as against 78 per cent passing a 
200-mesh sieve of the present-day standard. But only in com- 
paratively recent times was the further discovery made of the value 
of proportioning the constituents of concrete in such a manner 
that the voids of the stone, or largest aggregate, are completely 
occupied by the sand, the voids of the sand by the cement, and 
the whole united by the hydration of this cement in the presence of 
water. Though this is theoretically correct, in practice it is found 
necessary to use about 10 per cent of extra cement to obtain the best 
results; first, because of incomplete hydration of the cement; 
secondly, because of the practical impossibility of exact grading of 
aggregates; thirdly, because of insufficient mixing, tamping and 
supervision of details. 

Methods of Making Dense Concrete. Concrete may be mixed 
either by hand or by machine, both methods, if properly applied, 
giving about the same grade of concrete, though the balance is 
always in favor of machine-mixed concrete. The work done by 
hand is likely to be uneven in quality, and some batches will be less 
thoroughlly mixed than others, while machine-mixed concrete is 
usually of a more uniform quality and is generally less expensive. 
Hand-mixed concrete is employed only when the quantity is small 
or when machinery is unobtainable, but not where uniformly dense 
and impervious concrete is an essential factor. 

The fundamental requirements for obtaining self-densified 
mortar or concrete are: (1) destruction of the inherent porosity 
of the mortar or concrete; (2) scientific proportioning of aggregates; 
(3) careful supervision and good workmanship. 

The inherent porosity of concrete is due partly to the fact that 
only about 20 per cent of the cement* used in making concrete is 
hydrated, or, in other words, acts as a cementing material, the other 
80 per cent remains lying in the pores as so much inert matter, but 
only partly closing the pores; and partly to the fact that since every 
62J pounds of water weight in concrete occupies 1 cubic foot of space, 
which amount of water, if lost by evaporation or drainage during the 
setting period, means 1 cubic foot of voids remaining in the mass. 
Again, improperly graded aggregate or poorly proportioned mixtures, 
or both, are very conducive to porosity in concrete and not so easily 
remedied. Too much water and too little mixing are factors in the 
workmanship which often results in porous concrete. 

* See series of articles on microscopic study of concrete by N, C, Johnson, 
in Engineering Record, January, February, March, 1915, 


The porosity due to the first two causes, i. e., insufficient 
hydration and excessive evaporation, may be reduced, first, by 
mixing each batch longer than is now common in practice (with the 
significant slogan in the industry of " a batch a minute "), and, 
secondly, by mixing with just sufficient water to obtain a medium 
or mushy consistency. Concrete of this consistency may be defined 
as a mixture of cement, sand, and stone or gravel of jelly-like con- 
sistency, which is not watery, but can be spaded and readily 
worked into place in the form. This consistency is illustrated 
in Fig. 21.* 

Coarseness of sand and aggregate, is also effective in reducing 
porosity and absorption, although gravel seems to produce the 
denser concrete, f In fact, gravels are preferable to crushed-stone 
aggregate, particularly for underwater work, because they mix 
and settle in place more easily. Either crushed stone or gravel 
may be used, however, if carefully handled. But bank-run gravel 
should never be used, as its quality is not uniform. 

Scientific Proportioning. The second essential requirement for 
the production of impermeable mortar or concrete is scientific 
proportioning. It is of the greatest importance that concrete 
should be made as dense as possible if it is to be made impervious, 
that is, that it should have the smallest practicable percentage of 
voids. This is best accomplished, or, at least, the various methods 
tending toward this result in practice are as follows : 1 

(1) Arbitrary selection; one arbitrary rule being to use half as 
much sand as stone, as 1 : 2 : 4 or 1 : 3 : 6; another, to use a volume 
of stone equivalent to the cement plus twice the volume of the sand, 
such as 1 : 2 : 5 or 1 : 3 : 7. 

(2) Determination of voids in the stone and sand, and pro- 
portioning the materials so that the volume of sand is equivalent to 
the volume of voids in the stone and the volume of cement slightly in 
excess of the voids in the sand. 

(3) Determination of the voids in the stone, and, after selecting 
the proportions of cement to sand by .test or judgment, proportion- 
ing the mortar to the stone so that the volume of mortar will be 
slightly in excess of the voids in the stone. 

* Technologic Paper No. 3, Bureau of Standards, Washington, D. C. 

t Engineering News-Record, Vol. 79, No. 16, p. 740. 1917. 

J " Proportioning Concrete," by Sanford E. Thompson, Journal, Association 
Engineering Societies, Vol. 36, April, 1906, t . 185. 

Proportioning by voids has seemingly been proven fallacious. See Techno- 
logic Paper No. 58 of the U. S, Bureau of Standards, p. 39. 





FIG. 21. Appearance of Gravel Concrete of Three Consistencies. (From 
United States Bureau of Standards Technologic Paper No. 58.) 


(4) Mixing the sand and stone and providing such a proportion 
of cement that the paste will slightly more than fill the voids in 
the mixed aggregate. 

(5) Making trial mixtures of dry materials in different pro- 
portions to determine the mixture giving the smallest percentage of 
voids, and then adding an arbitrary percentage of cement, or else 
one based on the voids in the mixed aggregate. 

(6) Mixing the aggregate and cement according to a given 
mechanical analysis curve. (See Appendix I.) 

(7) Making volumetric tests or trial mixtures of concrete with 
a given percentage of cement and different aggregates, and selecting 
the mixture producing the smallest volume of concretes; then 
varying the proportions thus found, by inspection of the concrete 
in the field. 

The two most practical methods, however, for accurately deter- 
mining the proportions of each material is by mechanical analysis 
of the aggregates and volumetric synthesis, or proportioning by 
trial mixtures. The method of proportioning concrete according to 
Fuller's curve gives 1 I 1.41 : 4.34 as an ideal mix for producing the 
densest concrete. 

From the above methods of proportioning the following laws, 
which relate especially to the grading of the aggregate, have been 
evolved : 

1. Aggregates in which particles have been specially graded 
in sizes so as to give, when water and cement are added, an artificial 
mixture of greatest density, produce concrete of higher strength 
than mixtures of cement and natural materials in similar proportions. 

2. The strength and density of concrete is affected but slightly, 
if at all, by decreasing the quantity of the medium size stone of the 
aggregate and increasing the quantity of the coarsest stone. An 
excess of stone of medium size, on the other hand, appreciably 
decreases the density and strength of the concrete. 

3. The strength and density of concrete are affected by the 
variation in the diameter of the particles of sand more than by 
variation in the diameters of the stone particles. 

4. An excess of fine or medium sand decreases the density and 
also the strength of the concrete, as will also a deficiency of fine 
grains of sand in a lean concrete. 

5. The substitution of cement for fine sand does not affect the 
density of the mixture. 

6. In ordinary proportioning with a given sand and stone and 
a given percentage of cement, the densest and strongest mixture is 


attained when the volume of the mixture of sand, cement and water 
is so small as just to fill the voids in the stone. In other words, in 
practical construction, use as small a proportion of sand and as 
large a proportion of stone as is possible without producing visible 
voids in the concrete. 

7. The best mixture of cement arid aggregate has a mechanical 
curve resembling a parabola, which is a combination of a curve 
approaching an ellipse for the sand portion and a tangent straight 
line 'for the stone portion. 

Grade of Workmanship and Supervision Necessary for Water- 
tight Concrete. The third requirement is careful workmanship and 
supervision, particularly the latter, for obviously, where the engineers' 
directions are not followed, or orders are neglected; where supervi- 
sion or inspection is lax, little can be done in the way of making 
dense concrete, in spite of willing and conscientious help. In this 
connection it is also well to remember that when inexperienced 
laborers or foremen are depended on to produce an impervious 
concrete, no scientific proportioning or prolonged mixing will turn 
the doubtful balance in favor of the concrete. To produce impervious 
concrete it is imperative to give strict supervision to details, and 
this phase is usually neglected by inexperienced labor. To accom- 
plish these various objects, alert foremen and experienced workmen 
should be selected, and details of design and construction carefully 
attended to. 

From the foregoing articles it may be seen that a 1 : 2 : 4 con- 
crete is for all practical purposes impermeable, and that with scientific 
proportioning of ingredients and grading of aggregates, as outlined 
above, a 1 : 3 : 7 concrete can be made almost equally impervious. 
Further, the maximum density of concrete is obtained when the 
particles lay as close together as possible. Consequently its imper- 
viousness depends upon the varying degree of roughness of the 
stone and sand, the relative sizes of stone, sand and cement, the 
proportionate quantities of the various sizes, the readiness with 
which the materials compact, and the amount of water used. The 
sizes and quantities being determined and adhered to, careful work- 
manship and cautious supervision will do the rest. 

The use of these ingredients according to the varied but specific 
methods outlined, in no way alters the present standard methods of 
mixing and laying concrete. A variation though, in the general 
method of mixing concrete by machine must be noted because of 
its successful accomplishment in the matter of producing dense and 
impervious concrete. Contrary to the prevalent adverse opinion 


of the practice of mixing concrete by first turning on the water and 
then dumping the aggregate into the mixer, this practice, slightly 
modified in that each material is put into the drum separately, 
starting with the water, followed by the cement, the sand, and 
finally the large aggregate, the drum revolving continuously, actually 
produces very impervious concrete. This practice is now resorted 
to in the manufacture of reinforced concrete water pipe. 

Wherever the three essential requirements can be fulfilled and 
the suggestions for making them effective followed, there is but 
little need to add any waterproofing compound, providing the struc- 
ture is not subject to vibration and other harmful physical influences. 
If it is subject to such influences, then the only systems well adapted 
for the waterproofing, especially on large engineering structures, 
under these conditions, are the membranous or sheet mastic sys- 
tems, or, possibly, the surface coating system and in some cases, the 
grouting process. However, by the judicious arrangement and 
distribution of well-made and watertight expansion joints, all water- 
proofing may sometimes be eliminated, even in the non-rigid type of 

The general subject of the self-densification of mortar and con- 
crete is treated exhaustively in standard works on concrete, and 
for more particular and detailed information, these may be con- 
sulted to good advantage. 


Definition, Purpose and Development. Waterproofing by the 
grouting process means the placing (usually) of a very wet cement 
mortar behind and around a finished iron or masonry tunnel or other 
underground structure, injected through the walls or some portion 
of its body. The mortar or grout is forced, generally by means 
of a pneumatic grouting machine, through cracks, joints, or pipes 
suitably located in the structure, until refusal, or until there is 
evidence of the grout having filled all the seams in the rock, or per- 
meated the ground in the immediate vicinity of the structure. The 
purpose of this is to force the ground water to find or make new 
channels for itself, so that it will not come in direct contact with the 
structure, which may not be sufficiently watertight in itself to prevent 
seepage. The mortar or grout is, of course, in itself very impervious. 
This follows from the richness of the mixtures used, in many instances 
being nothing more than a neat cement. In fact, such mixtures, 
that is, either neat cement, grout, or mortar, form the most imper- 


vious materials, and constitute the best waterproofing mediums if 
applied in the proper place and manner. For the grouting process, 
these materials are well adapted, and serve their purpose admirably. 

This system or process of waterproofing is well adapted for solidi- 
fying masonry, various soils * and fissured rock, for sinking wet con- 
struction shafts, and for driving tunnels in unstable and water- 
bearing material, for cutoff walls and in general where great water 
pressures are to be resisted by the finished structure as, for instance, 
around tunnels underneath river beds. Grout is also used in tunnel 
headings which must pass through water-bearing ground, to fill 
the voids in the dry packing over a tunnel arch or elsewhere, to 
cut off heavy flows of water from cracks, seams, and fissures in the 
rock about the tunnel or its shafts, in the solidification of rock and 
quicksand at dam sites, and to insure a watertight contact with, 
and the complete protection of, steel work imbedded in the masonry. 
In fact the grouting process has a wider field of usefulness than is 
generally known. 

The grouting process originated or was invented before 18P1, but 
was only patented in that year. The inventor, Mr. Robert L. 
Harris, set forth many of the possibilities of this process, and to-day 
it is a recognized engineering procedure and is used on practically 
all tunnel construction, though somewhat modified in method. 
One of these modifications, perhaps the most radical and of very 
recent origin, consists of a pneumatic concrete machine that mixes, 
conveys and places the concrete in one continuous stream and 
operation, producing a reasonably dense, and impervious concrete. 
This process eliminates dry packing over arches of tunnels, permits 
the placing of the complete ring of tunnel or lining but does not 
readily fill up seams or fissures in the natural rock. This particular 
apparatus is still undergoing improvement and promises fair to be a 
most important addition to the engineer's equipment of machines 
for making and placing dense mortar and concrete. The grouting 
process in general will have a wider field of usefulness when its 
operation and manipulation, its simplicity and effectiveness are 
better understood, and the apparatus perfected, resulting also in 
greater economy in its application. 

* In sinking a large steel caisson shaft for constructing a tunnel under the 
East River to connect the new subways between Brooklyn and Manhattan, 
New York City, the bulkheads of the caisson contained a number of 2^-inch 
diameter openings, capped during sinking, and used for consolidating the sur- 
rounding material by grouting. Public Service Record, Vol. 3, No. 3, March, 
1916. Published by the Public Service Commission, 1st District, State of New 


Application of Grout for Waterproofing. To secure good results 
from the grouting process, great care must be exercised in conducting 
the work. This work is most advantageously carried on at a rea- 
sonably low temperature. Attention to details and a thorough 
understanding of the nature of the problem at hand are necessary. 
In the case of driven tunnels, for instance, great judgment and care 
are required in panning off running water so that none of it will come 
in contact with fresh concrete; and such considerations as the best 
method of drilling and placing holes for grouting, the proper con- 
sistency of the grout mixture, the best cement to use, what injection 
pressure should be applied, the best means of producing and control- 
ling the flow of grout, are matters vital to the success of the process. 
But these are not difficult to determine as a rule by the performance 
of a few preliminary field tests. 

In tunnels grouting under pressure is not done until some time 
after placing the complete ring of masonry lining at the location 
to be grouted, except to reduce leakage in wet ground, or in connec- 
tion with sections of masonry lining built to control such leakage 
or to support wet and heavy ground. Generally, grout is mixed 
as thick as can, with certainty, be made to completely fill the voids. 
Good proportions for grout are 1 : 1 (or 1-|) : 1. Sand or stone dust 
and either Portland or natural cement can be used to equal advantage. 
Grouting should be carried on continuously at any particular seam 
or void until completed, without intermission sufficient to allow 
the grout to take an initial set. The grout should be delivered uni- 
formly and steadily to avoid occluding air in the interstices of the 
dry packing. This is usually accomplished by using two grouting 
machines so that while one is shooting grout the other is being 
charged. This is especially necessary where large seams or voids 
in rock are to be grouted. 

For filling large voids thick grout is best, but for small cracks 
and fine seams a thin mixture should be used, as, for instance, a 
mixture so lean that the water will carry the cement as far as possible 
into the fine seam and so avoid blocking up close to the drill hole. 

In tunnels through rock, all voids over the arch should be filled 
without requiring the grout to travel a great distance, not more than 
25 feet after leaving the grout pipe. Grouting of any section of 
tunnel should begin at the bottom and proceed uniformly upward, 
unless some other order is found more desirable. If the upper ends 
of each series of grout pipes are at different elevations, the grouting 
should invariably begin at the lowest pipes, and no higher pipe con- 
nected until the grout from a lower pipe begins to flow out of it (see 



Figs. 22 and 134). Cutoff walls of masonry are sometimes built 
tight against the roof and across the arch of the tunnel, dividing 
the space above the arch into sections. This makes more certain 
the filling of the voids in the packing of that section, except in unsound 
rock where the grout can flow around the cutoff, or where the cutoff 
has not been properly made. 

Grouting is usually considered completed when no more grout 
can be forced into the seam, void or dry packing space under the 
required pressure. 

Cement and Sand for Grouting. Various materials are sometimes 
found effective for grouting purposes. For instance, muddy water, 
liquefied clay, soft clay, and ground horse manure have been used 

FIG. 22. Electric-driven Compressor Connected to Grout Mixer, Showing 
Arrangement of Equipment and Use of Grout Pipe. 

alone or with cement for sealing fissures in rock or cracks in massive 
concrete. But grout alone is usually and most extensively used with 
marked success on all kinds of underground structures, success de- 
pending, however, on the care and attention exercised in applying it. 
Though Portland cement is the most commonly used, natural cement 
may be used. Sand cement is also used and is found very efficient 
because it not only sets as well as Portland cement but seems to 
mix better and produce a smoother flowing grout.* However, almost 
any standard commercial but preferably quick-setting cement is 
suitable for grouting. 

The best sand for grout is that grade which will pass approxi- 
mately 100 per cent through a sieve having 64 openings per square 
inch and approximately 45 per cent pass through a sieve having 

* Engineering News-Record, Vol. 78, No. 13, p. 627. 1917. 


1600 openings per square inch. If it is desired to use stone screenings 
instead of sand it should be the finest obtainable or such as will pass 
at least 60 per cent through an 8-mesh sieve, 85 per cent retained on 
a 50-mesh sieve and 90 per cent retained on a 100-mesh sieve. The 
quantity of water necessary to form the mixture depends on the 
physical condition of the ground, rock or masonry to be grouted as 
well as upon the condition of the sand or stone screenings. It is 
always best to commence with a very liquid mixture, say one part of 
cement to five or seven parts of water, by volume, increasing the 
amount of cement untill a 3 : 6 to 3 : 7 (sand : water) mixture is 
obtained. But it is not possible to adhere to any set rule in 
grouting, therefore the operator should possess both judgment 
and experience if the greatest efficiency and economy are looked 

Equipment for Grouting Process.* The best equipment to use 
for forcing grout into the spaces to be filled depends upon the pres- 
sure necessary to make the grout travel, and the consistency of the 
mixture best adapted to the size and kind of voids to be filled. If 
a considerable yardage of grout is required a large capacity equip- 
ment is best, but where a small quantity is to be placed, especially 
under high pressure, a different equipment is necessary to secure 
the best results. In the past, and to a certain extent at present, 
grouting has been done by pouring the mortar or grout through pipes 
arranged in such a way as to secure the necessary pressure. Gener- 
ally, however, more pressure than that afforded by the head of grout 
alone is required. 

The equipments ordinarily used at the present time are as follows : 
(1) Reciprocating pumps furnishing a continuous flow with inde- 
pendent means of mixing the grout; (2) Pneumatic mixers and 
placers, which are of two classes f- (a) paddle mixing and air ejecting, 
(6) air mixing and air ejecting; (3) paddle mixing and water ejecting. 
A paddle mixing and air ejecting type of grout tank has been exten- 
sively used on shield-driven tunnels. This type is well adapted for 
placing large quantities of grout, as in* grouting dry packing behind 
tunnel linings, especially over the arch. 

A tank of the air-mixing and ejecting type was used very largely 
on the work of the New York Board of Water Supply, particularly 
in grouting shafts and pressure tunnels. To counteract the extremely 
high head over the Hudson crossing, a Cameron pump was used to 
force water into the grout tank. This raised the pressure as high 

* Engineering News, May 6, 1916, Vol. 75. 

f Developed and patented by William Lester Canniff in 1907. 


as 600 pounds per square inch, which was sufficient to force the 
grout in against the external head. 

Great care must be exercised in the manipulation of these types 
of grout mixers as, for instance, to shut off the discharge valve the 
instant the last bit of grout leaves the tank; otherwise an afterblast 
of air follows, which stirs up the grout, air collects in the spaces 
to be filled by the grout and is displaced only with great difficulty. 

The paddle-mixing and water-ejecting type of grouting machine* 
is a newly invented modification of the ordinary grout mixer. This 
water-ejecting type seems better suited than the air-ejecting types, 
when great pressure is required, to accomplish the ejecting process 
against a great head. This water-ejecting grout machine can be 
and is also used for low heads with ordinary pressures. Its main 
object, however, is to provide an inelastic driving power, formed by 
a fluid (water) piston, for forcing out the grout. As built, this 
machine is more easily and certainly controlled and dispenses with 
air compression when water under a head is available. Its limited 
use does not yet permit a statement of its relative efficiency when 
compared to the air-using mixers. 

The following description of the equipment employed in grouting 
the City Tunnel (Manhattan) of the Catskill Aqueduct is partic- 
ularly interesting because it was evolved there and used with 
remarkable success. It is in fact a typical equipment for all deep 
tunnel grouting. Figs. 22 and 23 show the arrangement of the plant 
commonly used on the Catskill Aqueduct, and which was adopted 
in some sections of the City Tunnel. Air, piped from the compressor 
plant on the surface, was delivered directly to the grout tanks at a 
pressure of from 80 to 100 pounds per square inch for the low-pressure 
work. When the grouting required higher pressure the air was 
further compressed to 200 or 300 pounds per square inch by means 
of an auxiliary air-driven compressor or " booster," supplied from 
the compressor at the surface. Fig. 22 shows a type of equipment 
in which the low-pressure grouting was carried on as usual with the 
air furnished from the surface compressor plant. The high-pressure 
grouting was also done with a small compressor driven from the light- 
ing or power circuits. With a plant as shown in Fig. 23, both the low- 
and high-pressure grouting was done with the electrically driven 
compressor in the tunnel. The adoption of this equipment, in which 
the compressor in the tunnel is operated only when grouting is 
actually being done, makes unnecessary the more or less continuous 
operation of the large compressor plant on the surface and effects a 
* Patented by S. C. Hulse, February. 1917. 













further economy in avoiding the piping of compressed air through 
the tunnel for grouting work. 

Many good details of operation and experience with the grouting 
process are described in a series of articles by Mr. James F. Sanborn,* 
Division Engineer, Board of Water Supply, New York, which are well 
worth persual by readers contemplating similar work. 

Steam-pressure Concrete Mixing and Placing Machine. A new 
machine embodying the principles of both the grout mixer and 
cement gun has recently been developed and used for making water- 
tight concrete direct by materially increasing its density during 
placing. This machine is called a concrete atomizer and the details 
of its operation are as follows : f 

The machine illustrated in Fig. 24, A, can make concrete weigh- 
ing about 170 pounds per cubic foot. Superheated steam at from 
75 to 80 pounds pressure is turned into the mixing chamber while 
the concrete is being thoroughly mixed by mechanical means. The 
mixture is then discharged through an outlet, and a fresh supply of 
superheated steam takes it to the form at high velocity through a 
special hose, which is provided with a nozzle opening which can be 
instantly increased to the diameter of the hose in case it is plugged. 
Where conditions prevent the use of steam, superheated compressed 
air gives almost as good results. Fig. 24, B, shows a plant where 
high-pressure steam is supplied from a locomotive, passed through a 
reducing valve, and superheated to supply the mixer. The super- 
heating effectively prevents condensation of water in the stream of 
concrete being delivered from the nozzle to the point of work, and 
enables the workman to see the face upon which he is playing the 

The pressure and superheating produce a concrete of considerably 
increased strength, while the force with which the mixture is applied 
gives it great density. A thin slab placed in this way has been found 
to be waterproofed under high water pressure. When the amount 
of mixing water is properly regulated little aggregate is lost by falling 
from the working face, and sections 1 foot in thickness have been 
placed in continuous operation on vertical walls. One of the photo- 
graphs shows this machine at work repairing a concrete retaining 
wall. It has also recently been successfully employed to reline a 
badly leaking tunnel with gravel concrete about 5 inches thick, t 

* " Grouting, an Effective Remedy for Stopping Leakage in Tunnels and 
Shafts," Engineering Record, April 15, 22, and 29, 1916. 

t Invented and described by Harold P. Brown in Journal of American Con- 
crete Institute, Vol. Ill, No. 7, July, 1915. 

I Proceedings American Concrete Institute, Vol. 12, 1916. 



FIG. 24. 

A. "Concrete Atomizer," which Turns Out Concrete under 80-lb. Steam 

B. Mixer Outfit at Work on Delaware, Lackawanna & Western R. R. 
Retaining Wall, Newark, N. J. 


Impervious Roofing Defined. The subject of impervious roofing 
is vast and complex, and we can only hope to cover its more general 
aspects with as much detail as is consistent with the practical limits 
desired for this chapter. The term " Impervious Roofing " is taken 
to mean those materials which are used as a topmost covering for 
any form of building construction and whose main function is to 
create a watertight roof. These materials always require properly 
constructed supports regardless of the character of the roofing or 
structure. Impervious roofing, however, does not include the sup- 
ports, such as trusses, beams, purlins and rafters, but does include 
everything else such as sheathing boards, masonry tiles and slabs 
or other suitable sheathing materials, which are placed upon the 
roof supports for the double purpose of providing a uniform and 
continuous surface for receiving the waterproofing materials and 
adding to the protection of the interior from the elements. Rain, 
hafl and snow are, of course, the particular scourges which create the 
necessity for making roofs absolutely watertight. The cost of roof- 
ing depends on so many different factors, that no worth-while 
estimate could be given as a general indication of the relative saving 
to be expected from the use of the types explained below. However, 
one thing should be borne in mind, namely, the annoyance and 
maintenance expense occasioned by leaky and short-lived roofs, 
are hardly compensated for by any possible saving in first cost. 
The following considerations should guide the selection of a roofing:* 
(1) Chance of leaks due to character of construction; (2) Probable 
life, including chance of damage by the elements and by wear from 
other causes; (3) Fire-resisting value; (4) Cost of maintenance; 
(5) Cost of materials; (6) Cost of laying. 

The simplest form of roof is the primitive flat roof of the Orient 
made with cross beams, thatch, and a heavy layer of stamped clay, 
which made the roof more or less watertight. In central Syria and 

* American Railway Engineering and Maintenance of Way Association, 
Bulletin No. 131, January 19, 1911. 



in Egypt important buildings were roofed with beams and" made 
watertight with slabs of stone. The Greeks used mainly low- 
pitched, gabled roofs protected with tiles of marble or terra cotta. 
The Romans were the first to use domes of brick or concrete covered 
with cement and lead sheeting for watertight ness. On elaborate 
structures the roofs were covered with tiles or with bronze plates. 
In the mediaeval cathedrals the roofs, which invariably had a very 
steep pitch, were for the first time in history sheathed with boards, 
then covered with slate, tiles, sheet copper or lead. The Italian 
classic type of roof was made nearly flat; and this type now pre- 
dominates in tropical and subtropical climates. Steep roofs quite 
obviously predominated in regions of much rain or nnow, as in 
northern countries, and continue to do so. Most modern roofings 
have not the same architectural beauty as those of ancient classic 
types, but they are more economical and efficient, also more varied 
and numerous in material and design than the old roofings. Some 
of the more important ones will be considered separately in the 
following articles. 


Wood Shingles. For securing watertight roofs, many materials 
are now in common use, all of which fall under four general heads of 
roofing, namely: the shingle roof, the tin roof, the felt roof (also 
called the composition of built-up roof), and the functional roof. 
The oldest and most commonly used^ of these roofings is the shingle 
roof. Wooden shingles are universally used for this purpose. These 
are made of various woods, such as cypress, redwood, cedar, juniper, 
white pine and spruce; this also being the order of their durability. 
Cypress is the most durable of wood shingles, though, as with all other 
woods, it is only the heartwood that shows greatest durability.* 
On the other hand redwood is much less inflammable than any of the 
others and spruce is the cheapest. Wooden shingles are usually 
packed in bundles (four of which constitute a " thousand," or the 
equivalent of one thousand shingles 4 inches wide) sawed to dimension 
sizes, which range from 4 to 6 inches wide and 16 to 24 inches long, 
or in random sizes, which range from 2J to 16 inches wide and 16 
to 24 inches long. Wood shingles are easy to apply, being fastened 
to the sheathing boards with two or three nails driven into the part 
that will be covered by the exposed portion of the superimposed 

* Cypress shingles were laid on a roof of a building in Greenwich, Conn., in 
1640 and were serving well 250 years afterwards. 


shingle. Unfortunately it is almost impossible to secure nails that 
will not corrode before good shingles will deteriorate, hence 
the shingles become loosened and displaced. The use of pure 
iron nails, rather than galvanized iron nails, will reduce this hazard 
to a minimum. No shingle should show more than one-third of its 
face to the weather. For the number required and the covering 
area of shingles, see Table XXXVII. For protecting wooden 
shingles from rapid incineration and deterioration, they are usually 
dipped into fireproof liquids, such as solutions of sodium silicate 01' 
aluminum sulphate, or coated with a wash mixture composed of 
lime, salt and fine sand or wood ashes. The sodium silicate, however, 
is readily soluble in water hence it will wash off unless the shingles 
are given a top coat of oil or paint; and the lime-salt-sand solution 
will not stick long unless also covered with a coat of oil or paint. 
The most effective and in the end the economical way would be to 
paint the shingles with a zinc borate paint. This paint is also 
remarkably fireproof. For preserving purposes such salt solutions as 
zinc chloride and sodium fluoride; or such oils as carbolineum and 
dead oil (creosote oil) are much used. The shingles are dipped in 
either of these for a period determined by experiment but usually 
depending on the grade of wood used. If creosote oil is objection- 
able, then besides the above salt solutions a solution of persulphate 
of iron of 2 to 2J deg. Baume", can be substituted. But if the per- 
sulphate of iron solution is used then it is advisable to top coat the 
shingles with hot, raw, linseed oil. Often, however, besides receiving 
preservative treatment the shingles are painted or stained to create a 
pleasing effect. Since dipping the shingles is mainly for their pres- 
ervation, they are completely submerged in the liquid, but in paint- 
ing them, which is mainly for appearance, only the weather portion 
of the shingles is coated. However, unless this is done with the 
greatest care, it would be better to paint the whole shingle, because 
otherwise dry-rot will hardly be prevented. For shingles that are 
merely to be stain-treated (they can be stained almost any color), 
the staining is best and most durably applied by dipping. 

Slate Shingles. Next in general use are slate shingles, especially 
the black and the red varieties, but various shades of green and gray 
are also used. These are supplied commercially in thicknesses of J, 3^, 
and J inch, increasing by | inch, to 1 inch. Slate should be hard 
and tough, and have a well-defined vein, which must not be too 
coarse; if the slate is too soft, it will absorb moisture, if too brittle, 
it cannot be cut and punched without splitting, and it will easily be 
damaged by walking on the roof. A clear metallic ring when the 



slate is struck is an indication of its soundness; a muffled sound 
indicates a cracked or soft condition. For the number of shingles 
required per square of roof surface, see Table XXXVII. Slate 
shingles are usually attached to the sheathing over two or more 
plies of treated felt. Sometimes this felt membrane is cemented 
with a bituminous binder. Occasionally the slate shingles are laid 
up in neat cement, or rich cement mortar, but more often they are 
nailed to the sheathing boards like wood shingles (see Fig. 25). On 
irregularly shaped roofs and in locations near hips and valleys and 
flashings great care and skill are required in laying the shingles so 
as to avoid leaks. For these places tin is often used but copper or 
sheet lead are best adapted for the purpose. 


FIG. 25. Typical Details of Slate Roofing 

Slate shingles are often attached to concrete or porous terra- 
cotta roofs, by being nailed directly to the surfaces. This is poor 
practice especially on roofs having the minimum allowable pitch. 
A means for attaching them more securely is to nail 1} by 2 inch- 
wood strips to the outer face of the concrete or terra cotta, the 
strips being set the proper distance apart to receive the slate 
shingles, and then plastering between the strips with cement mortar. 
This gives a good nailing base for the roofing. Among the best 
impervious roofings that can be put on a flat or moderately inclined 
roof is one of slate shingles, laid over a membrane of five plies of 
treated felt. The membrane is applied with bituminous binder as 
for a felt roof, and the slates bedded on the membrane in cement 


mortar.* For this arrangement the shingles/ are thicker than ordi- 
nary and laid butt-joint fashion. 

Tile Shingles. Next in order of usage are tile shingles. Clay 
tiles were used before historic times, and, of course, all down the 
ages there has been considerable improvement in the product. Not, 
however, till 1851, when the first tile-making machine was invented, 
did the manufacture of clay tiles assume a real industrial aspect, 
as previously all tiles were made by hand. To-day the tile industry 
is extensive and exists practically in all countries of the world. 
Tiles are manufactured in various sizes and forms and of such 
materials as clay, shale (vitrified tiles), cement mortar, and even 
reinforced concrete. (See Figs. 27, 28, and 29.) Clay roofing tiles 
properly made, that is, well-glazed and hard-burned throughout, 
cannot be excelled for durability. The application of vitrified tiles 
often depends on their form. Some are curved on both ends and 
hook on each other downward from the ridge tile, which is straddled 
on the ridge pole; some are rectangular (the usual dimensions being 
1J by 6 by 9 inches), and of various shades, such as red, black, green 
and gray. It is harder to get a tight roof with ordinary tile than 
with slate, but the interlocking shapes that have been devised give 
very good results in this respect. Sometimes the tile is imbedded 
in a plastic cement or in cement mortar upon an underlying three- 
to six-ply built-up felt roof, replacing the gravel. In fact, this 
scheme has become the practice for roofs of modern high and expen- 
sive buildings. Flat porous tiles similar to the above, but of larger 
size are usually attached in the same manner as slate shingles. 
Sometimes the large-size tile is laid directly on steel or wooden 
purlins, which must be spaced to suit the length of the tile. 

The cement tiles are of various shapes and sizes; those shown in 
Fig. 28 being an extensively used type. They are, of course, fire- 
proof as well as waterproof, strong and practically permanent. 
They are usually made so as to lay directly on the purlins. 

The reinforced concrete roofing tiles are mostly home made, so to 
speak. They can be made anywhere in all sizes, shapes and colors, 
hence are very adaptable for special purposes. Reinforced concrete 
roofing tiles were extensively used on nearly all superstructures of 
the New York Catskill Aqueduct. Because of their relative high 
cost their use is limited to elaborate and expensive structures; but 
because of their permanence and serviceability they should have a 
wider usage. In this connection the following brief suggestions for 
making reinforced concrete tiles will be of material aid. 

* Kidder's " Architects and Builders Pocket Book," p. 567. 



Success in using reinforced concrete roofing tiles depends on the 
care with which they are made, handled and placed. The first 
requisite is that they be made impervious to water and as dense 
and strong as practicable. The thickness of tiles varies from f inch 
to 3 inches, depending on appearance and extraneous functions. The 

FIG. 27. Baked-clay (Vitrified Tile) Roofing, Showing A, Spanish; B, German; 
and C, Closed-shingle Types. 

thickness of pan (flat) tiles (as used on the above mentioned work*) 
except at the ribs, or along the edges, was approximately If inches, 
being nowhere less than 1 inch, while the average thickness was not 

* New York Catskill Water Supply, Type " A " Reinforced Concrete Roof 


to exceed 1| inches (see Fig. 29). In placing the tiles upon the steel 
frames of the roof (and steel frames are preferably used for their 
support so as to obtain the necessary rigidity) , the steel should be 
covered with mortar or other suitable coating material for protection 
against corrosion. It is important that this covering be neither 
chipped, cracked nor otherwise injured. Flashings for tiles about 

FIG. 28. Types of Cement Roofing Tile. 

the chimneys should preferably be of sheet copper, such as weighs 
20 ounces per square foot. 

The best aggregate for concrete tiles is clean quartz, which con- 
tains both fine and coarse particles of suitable limiting sizes and is 
satisfactorily graded. All aggregates, however, should not contain 
sufficient loam or clay, or other objectionable matter, to render them 
unsuitable for making an impervious and uniformly clean-looking 














Tiles marked "X" 

Slight modificatioi 

tay be necessary. 



tile. For best results it is important to use clean water and to form 
a medium consistency concrete. In general the mixture may be 
approximately in the proportions of 1 : 2f to 1 : 3, the aggregates 
being measured by weight or volume, as found practicable. It is 
important to thoroughly mix the concrete in a good mechanical 
mixer, except that very small quantities may be mixed by hand. 
Concrete mixing by machine should be continued for at least ten 
minutes. No tiles should be made of retempered concrete. Where 
it is desired to tint the tiles, mineral coloring materials may be added 
during the mixing, but if the bottom surfaces are to be exposed 
inside of a building they should preferably be a very light gray or 
white. The top surface of tiles may be tinted by the surface applica- 
tion of a suitable paint. 

Steel reinforcement for concrete tiles should be ample, pref- 
erably of the mesh fabric variety, firmly fastened at each inter- 
section and properly placed. For reinforcing the ridge, hip, rib and 
finial tiles or other special shapes and the bearing lugs of pan tiles, 
steel rods about \ inch in diameter will be very useful in addition 
to the mesh reinforcement. The best practice is to put the steel 
in the lower part of the tile and every part of it at least -f$ inch 
from the surface. The reinforcement must be placed in exact 
positions specified by design, and held in position so as to prevent 
displacement while the concrete is being deposited and while it is 
setting. If the concrete is not sufficiently wet to thoroughly coat 
the steel with cement, it is advisable to coat the steel with cement 
grout as it is being placed in the form or immediately before 

After fabrication the tiles should be seasoned; that is, in order 
to avoid all manner of cracks, the tiles, on removal from the forms, 
should, during the first month, be kept constantly moist. It is very 
important that all the tiles should be true to the shapes required 
by the particular design; especially is it important to see that the 
flat tiles are not warped. Particular attention is also necessary for 
making those edges which bear on the surfaces of other tiles so 
true and smooth as to form good joints. Variations from any 
dimension ought not to exceed | inch. The tiles should be adjusted 
in place so as to give close joints where exposed to the weather, and 
so that each tile will have a satisfactory bearing. The exposed 
spaces between the soffits of the eaves tiles and the cornices should 
be pointed smooth with Portland cement mortar, which may be 
made to match the tiles in color. All joints should be made per- 
manent with an elastic roofing cement. Tiles having unevenness, 


voids or other objectionable imperfections which would reduce their 
impermeability, should not be used. 

To test the permeability of concrete tiles, at least two seasoned 
pan tiles should be placed separately in a horizontal position, top up, 
and subjected over the area which would be exposed in the roof, to a 
3-inch depth of water for seven consecutive days, after which a 
well-made tile should not show any dampness over the bottom. 
The strength of tiles may be tested by placing flatwise, horizontally, 
top up, a tile not less than twenty-eight days old, on rigid supports, 
one near each end of the tile and extending across its full width. 
Thus supported, a tile as illustrated in Fig. 29 should be able to 
support a central load of at least 600 pounds, applied gradually, 
bearing across the whole width of the tile. 

Prepared Shingles. Then there are what, for want of a better 
name, are called " Prepared Shingles."* Indeed, these shingles 
are fast becoming a very staple roofing material. Prepared shingles 
are composed of various materials, such as asbestos fiber compressed 
into boards of various thicknesses, sizes and shapes : or of two or three 
plies of wool and rag felt, saturated and coated with various grades 
of asphalt, made, smooth or rough-surfaced and cut into shingles 8 by 
12 J inches or 8 by 16 inches which are the two standard sizes; or of a 
thick, treated, wool-felt, surfaced either with fine sand cr carefully 
screened grit, but sometimes with mica flakes, or stone screenings 
(see Figs. 30 and 34) such as slate, feldspar and silicate, whose varied 
colors create pleasing roof effects. In the felt shingles, it is, of 
course, the asphalt (or coal-tar pitch) treatments which give the 
weather-resisting qualities to them. If unsurfaced, they are of light 
weight and sometimes the asphalt-treated shingles tend to disin- 
tegrate or the coal-tar pitch hardens and the shingles become brittle 
on exposure. Hence, the final surfacing with a layer of mineral 
matter serves a threefold purpose. 

In view of the growing importance of prepared shingles, the 
following instructions for applying them will be found helpful : 

The sheathing boards should be laid closely and securely nailed. 
It is necessary to see that the surface is clean and free of all pro- 
jecting nail heads or other obstructions. On particular work, it is 
good practice to first cover the sheathing boards with a single ply 
of building paper or treated felt. One row of shingles is laid length- 
wise along the entire lower edge of the sheathing, extending J inch 
over the edge of the sheathing or inner edge of the gutter. These 
must fit closely and each lower corner nailed, driving the nails 2 
* Prepared shingles were originated in 1901 and first marketed in 1910. 



inches from the lower edges and ends. One nail is driven half way 
between the two, thus using three nails to each shingle on this row. 
It is best to use 1-inch galvanized nails with large, flat heads about 
\ inch in diameter. 

The regular course should begin with a full-sized shingle, as shown 
in Fig. 30, laying same parallel to, and flush with, the outer edge or 
vertical end of the roof. The lower end is flushed with the first layer, 
allowing J-mch space between the shingles. The course is thus 
continued, using two nails to the shingle, driven 4| inches from the 
lower edge. The second row is thus begun with two-third-sized 

FIG. 30. Undersurfaced, Prepared-shingle Roofing. (A, Nails.) 

shingles, laid 4 inches to the weather, and nailed as the others. The 
third row follows with one-third-sized shingles and the same spacing, 
etc. In beginning the fourth row, full-sized shingles are again used 
and continued as before. The J-inch space between shingles allows 
for contraction and expansion and improves the general appearance. 
If shingles are laid 4 inches to the weather and 4| inches from 
the lower ends, all nail heads will be fully covered and protected. 
Metal should, of course, be used for all. flashings and for lining 

Asbestos Shingles.* There are on the market various brands of 
pressed asbestos shingles mostly cut to a standard size, usually 

* Originated in Austria. Patented in the United States in January, 1907. 



8 by 16 inches (see Fig. 31, A) which are in demand because they 
are both fireproof and waterproof. They are made of a mixture of 
asbestos and Portland cement and compressed to any desired thick- 

FIG. 31. 

A. The American or Straight-laid Method of Applying Shingles. 

B. The Honeycomb or Hexagonal Method of Laying Square-cut Shingles. 

C. The Diagonal or French Method of Applying Shingles. 

ness under hydraulic pressure. When new, they absorb between 
5 and 10 per cent by weight of water, depending on the compression 
they underwent. But when exposed to the air for any length of 
time, further hydration of the cement decreases their absorptiveness 


and increases their impermeability. The strength, durability, imper- 
meability and fireproof properties of asbestos shingles are important 
factors in overbalancing their high cost. Asbestos shingles like most 
others are also made in special sizes and forms (see Fig. 31, B) and 
sometimes are applied in the same manner as tile or slate shingles. 
Sometimes they are laid up in proprietary cements, a common 
cement for such purpose being a paste made of China wood oil and 
heavy petroleum residuum. 

There are three standard methods for applying shingles which 
will be described briefly in connection with the application of asbestos 
shingles, although these methods are equally applicable to other 
kinds of shingles. These are the American method, the Hexagonal 
method and the French method. But regardless of the method of 
application it is absolutely necessary that all asbestos shingles be 
very hard pressed, only slightly absorbent, reasonably strong, and 
cut to uniform size and thickness to secure the best results. 

American Method of Applying Asbestos Shingles. This method 
has many modifications of application, but the commonest way is 
as follows: 

The roof boards are laid so as to break joints and nailed securely 
in place, leaving no loose ends. They should be well-seasoned and 
preferably of a narrow width. One ply of felt is laid horizontally 
over the roof boards with a 2-inch lap, and with 6-inch laps on hips 
and valleys. Furring strips J to \ inch wide are laid under the felt, 
parallel to and flush with the eaves, and then one course of shingles 
is laid at eaves lengthwise and parallel to same, overhauling the eaves 
about \ inch. The second course of shingles entirely covers the 
first course (see Fig. 31, A), but breaking joints; after which the 
process is the same as with wooden shingles or slates, exposing not 
more than 7 inches to the weather and fastening each shingle in 
place with at least two galvanized iron roofing nails. Nails must 
never be driven down tight; it is only necessary to drive them 
firmly. Over the ridges and hips asbestos ridge and hip rolls should 
be applied with not less than 3-inch laps, fastened in place with ridge 
roll fasteners. Where the ridge pole does not project high enough 
above the roof boards to allow direct application of the ridge roll, it 
is necessary to put in a false pole, so that it is possible to get a direct 
fastening through the top of the ridge roll (see Fig. 32) . All chimneys 
and valleys must be flashed with copper or other suitable metal. 

Hexagonal and French Methods of Applying Asbestos Shingles. 
The Hexagonal method for applying asbestos shingles is as follows : 

The roof is prepared as in the American method. Furring strips 



i to \ inch thick by 1| inches wide are laid underneath the felt 
parallel to and flush with the eaves. Then one course of asbestos 
shingles is laid end to end, parallel with and overhanging the eaves, 
not less than J inch; over which is applied one course of shingles 
entirely covering the starter, breaking all joints (see Fig. 31, B). 
The balance of the roof is covered with shingles, 12 by 12 inches, 
laid as shown, exposing 9f by 9J inches to the weather. All shingles 
are fastened in place with galvanized nails, but the points of the main 
body shingles are fastened with copper storm nails. Here also the 
nails must not be driven down tight, but firmly. All the main body 
shingles should be laid with the diagonal lines on a 45-degree angle 
with the eaves. Over the ridges and hips asbestos ridge and hip 
rolls must be applied in the same way as for the American method. 
In applying the hexagonal shingles the same method is used as with 
the rectangular ones of the American method. 

FIG. 32. Details of Ridge Roll Construction. 

The French method is illustrated in Fig. 31, C, which is quite 

In general, shingles of all materials when well laid make a hand- 
some and watertight roof, and are easily replaced and repaired. 
They are serviceable on all but flat roofs, except as noted under 
slate and tile shingles. The minimum pitch for wooden shingles, 
slates, tile (when laid as roofing proper) and prepared shingles, is 
one-third, that is, 1 foot of rise for each 3 feet of span. Table VIII 
gives the minimum pitch for other roofing materials, but these 
values may vary somewhat, because each manufacturer usually 
establishes the incline upon which his own roofing should be applied. 

In connection with all shingled roofs, sheet lead is often used 
for gutters, flashings, etc. The weights recommended for these 
purposes are as follows: 

Gutters 7 pounds lead per square foot. 

Hips and ridges 6 pounds lead per square foot. 

Flashings 4 to 5 pounds lead per square foot. 


Table XXXV gives the thickness and weight of sheet lead. 
Where sheet lead is to be used to form rather large hips and other 
important parts of the roof, it is not desirable to lay it in greater 
lengths than 10 or 12 feet without a joint roll or drip to allow for 
movement due to the great expansion and contraction of lead from 
changes of temperature. 



Asphalt composition 1/24 

Tin (standing seam) 1/8 

Tin (flat seams) 1/24 

Corrugated iron 1/4 

Sheet iron 1/4 

Copper ....1/6 

Lead 1/6 

Thatch ,. 1/2 

Shingles 1/3 

Slate 1/3 

Tiles, terra-cotta 1/3 

Reinforced concrete slabs 1/24 

Ready roofing 1/24 

Felt, asphalt (or tar) , and gravel (or slag) (maximum) 1/4 


Properties and Application of Tin Roofing. The second type of 
roofing, that is, tin roofing, is applicable to both flat and pitched 
roofs, and is adaptable to special and difficult conditions, as well 
as practicable in every climate. Tin plate (which consists of iron 
or steel sheeting, tinned with an alloy of lead and tin), copper and 
zinc sheetings, are the most generally used for this purpose and their 
predominance is in the order given. The coat on the tin plate is, 
as noted above, mostly an alloy of lead and tin with the quantity 
of lead usually predominating. The best grade of tin is that which 
is coated with an alloy consisting of 30 per cent pure tin and 70 per 
cent pure lead. The weight of this coating varies between 8 pounds 
and 40 pounds per box of 112 sheets, 14 by 20 inches, depending on 
the thickness of the coat. Plates carrying less than 20 pounds 
should not be used for permanent buildings ; for such use 30 to 40- 
pound coating is most serviceable. Where the coating is all of 
lead it is called terne plate and this grade is generally used on inex- 


pensive roofs. Tin plates usually come in standard sizes, either 
14 by 20 inches, or 20 by 28 inches, with prepared edges to enable 
the roofer to make locked seams between them as they are applied. 
A modified form of tin-plate roofing consists of rolls of tin plates 
about 2 feet wide and of various lengths (between 10 and 50 feet) as 
required. These strips are applied by unrolling, joining and solder- 
ing them into a continuous sheet over the entire roof, usually with 
standing seams. Copper and zinc sheeting also come in standard 
sizes but are often made in any required size and thickness to suit 
the particular conditions of the roof. 

Tin plates for flat roofs are usually put on with the ordinary 
flat-lock joint, the sheets of tin being nailed under the lock. After 
the sheets are nailed and hooked together the hook joints are beaten 
down with a wooden mallet and then soldered. 

When it is desired to make some allowance for contraction and 
expansion the sheets are fastened with tin clips nailed to the roof as 
shown at A, Fig. 33; in this way there are no nails through the sheets 
of tin, being held in place by the clips. Fig. 33, B, shows a section 
of this joint.* 

To allow for greater ease of movement due to expansion and 
contraction and to reduce the use of nails and soldering of joints to a 
minimum, what are known as standing seams are used. These 
seams are always placed perpendicular to the eaves, but not carried 
into the gutter, where they would interfere with drainage or cause 
leaks through water making its way into the seams. Standing-seam 
roofs are fastened with clips nailed to the sheathing and turned 
down in the standing seam. Fig. 33 (C, D, E) shows a standing- 
seam roof in the different stages of construction. 

Fig. 33, F, shows the joint turned down as a flat lock joint. 

In standing-seam roofs or any roof where the tin is laid in long 
lengths the cross-joints should be double-locked; this is shown at 
G, while the ordinary single lock is shown at H. 

Tin roofs are sometimes put on in lengths running with the slope 
of the roof, the strips of tin being turned up and laid between 
strips of wood, as shown at J. This method provides ample allow- 
ance for expansion and contraction, and also enhances the appearance 
of the roof. 

Fig. 33, K, shows a method used for zinc and copper, while L 

shows how the cross-joints should be made at the ends of the sheet 

metal; a rise or step is made in the roof and the two sheets of 

metal turned and locked as shown. In working zinc care must be 

* Richey's " The Building Mechanics' Ready Reference." 



exercised in making the bends and angles, for if they are made too 
sharp the metal is liable to crack. 

Wherever any metal roof covering finishes at a wall or any place 
where flashing is necessary the roof metal should be turned up 8 or 
10 inches and securely fastened; then this metal should be counter- 







(Cleat Omitted) 

flashed and the flashing let into the joint of the wall at least 2 inches 
and well cemented. This is a part of the work that requires partic- 
ular attention so as to get everything watertight. 

In all metal roofing the main points are to get the joints water- 
tight and to make provision for expansion and contraction. 


* % 

As soon as the roofing is in place and the joints all soldered, it 
should then be painted. But just before painting, however, the 
metal roofing should be gone over and all grease, oil, resin, etc., 
removed with gasoline or benzene. 

Roofs of less than one-fifth pitch are best made with flat seams 
well locked together. The sheets of tin should preferably be of the 
small size, 14 by 20 inches, as the small sheets cause more seams and 
make a stiff roof which prevents buckling. Ordinarily, nails are 
driven through the edge of the sheet under the lock, but in good work 
the sheets should be fastened with tin clips or cleats nailed to the 
roof. This leaves the tin of the roof free to expand and contract. 
Nails or cleats should be used about every 6 or 7 inches. In solder- 
ing the seams rosin, and not acid, should be used, as the latter may 
attack and destroy the body of the tin, and great care should be 
exercised and time taken to " sweat " the solder well up into the lock 
of the seam. 

A standing seam should not be used on a roof of less than one- 
fifth pitch; as, on a flatter roof, while it may be tight for rain, in 
the winter the snow and ice will cause the water to back up under 
the seam. 

Tin roofing should always be painted on the under side to pre- 
vent rusting; a layer of good rosin-sized paper directly on the 
sheathing is of great benefit, as it absorbs the moisture from the rooms 
below, and acts as a cushion to the tin. 

The metal type of roofing is the most expensive, but is very 
durable (where a good grade of block tin or copper sheeting is used) 
and least troublesome if properly cared for; e.g., if a tin roof 
receives a coat of paint composed of raw linseed oil and iron oxide, 
once every two years, its life will be prolonged indefinitely. Perhaps 
the most objectionable feature present in a tin roof is its capacity for 
absorbing heat, which it retains, often to the great discomfort of 
dwellers directly underneath such a roof. Most roofers are very 
expert in the application of this type of roofing, hence it is more 
important to obtain a good quality of material than to issue exhaust- 
ive instructions for applying it. 


Applying Felt Roofing. The third and most modern method is 
the Felt or Composition roof. A felt roof generally consists of several 
plies of treated felt (a product of rag, pulp or asbestos) laid on a 
properly prepared surface and cemented together with coal-tar 


pitch or asphalt and generally (except the asbestos felt roofing) 
covered with slag, stone screenings or gravel (see Figs. 113 and 114). 
The felt may be treated with asphalt, oil tar, or coal tar, but the 
impregnation must be thorough in any case. The slag or 
gravel must cover the entire roofing surface so as to protect 
the bituminous coating from direct exposure, and to add weight 
to the membrane. For approximate weights of various roofings, 
see Table XXXVI. 

The method of applying felt roofings is practically standard; 
still, roofers and builders may find the following directions helpful. 
These directions* represent the best practice, but refer only to coal- 
tar pitch binder and felt. However, any good grade asphalt binder 
(of the right consistency for the local climate) and felt might be 
substituted, and equally good results obtained. 

First: One thickness of sheathing paper, or unsaturated felt, 
weighing not less than 5 pounds per 100 square feet, is applied, lapping 
the sheets at least 1 inch. 

Second: Two plies of saturated felt, weighing 14 to 16 pounds 
per 100 square feet, are applied, lapping .each sheet 17 inches over 
the preceding one, nailing as often as is necessary to hold it in place 
until the remaining felt is laid. 

Third: The entire surface is then uniformly coated with straight- 
run coal-tar pitch. 

Fourth: Three plies of treated felt are laid, lapping each sheet 
22 inches over the preceding one, and mopping the pitch the full 
22 inches on each sheet, so that in no place shall felt touch felt. 
Such nailing as is necessary shall be done so that all nails will be 
covered by not less than two plies of felt. 

Fifth: Over the entire surface is spread a uniform coating of 
pitch, into which, while hot, is embedded not less than 400 pounds 
of gravel, or 300 pounds of slag to each 100 square feet of surface. 
The gravel or slag should be from J to f inch in size, dry and free 
from dirt. 

The shea'ching paper, or unsaturated felt, is placed on the bottom 
next to the roof boards, mainly to keep any pitch which might 
penetrate the 2-ply felt above it from cementing the roofing to the 
sheathing boards. It also is of value in preventing the drying out 
of the roof through open joints from below. The saturated felts 
should be nailed not only to hold it in place while laying, but where 
there is any chance of disturbance of the roof from underneath by 
the wind. The practice in regard to nailing varies in different 

* Proceedings of Engineers' Society Western Pennsylvania, October, 1911. 


parts of the country, but the fewer nails the better, so long as the 
roof is held in place. 

The two layers of saturated felt first laid are necessary in order 
to carry and give full value to the amount of pitch which must be 
handled in one mopping. 

For a concrete roof, where the pitch does not exceed 1 inch in 1 
foot, nailing is not necessary, and the practice of applying the felt 
membrane is similar except that a dry sheet is not necessary, the 
concrete being first coated with pitch and the first two layers mopped 
the full 17 inches. Special care should always be taken in regard 
to flashing and to prevent the roofing from being loosened at the 
edge either by wind or fire. Most leaks occur around flashings 
and openings. 

After the original two layers of saturated felt are used, the 
additional layers are merely to give additional thickness of wearing 
material, and with a roof properly laid, the greater the amount of 
felt and pitch used the greater the life of the roof. Five plies are 
sufficient for most roofing purposes and when well applied make a 
very good roof covering. 

The coating of gravel, crushed stone or slag helps to hold the 
coal-tar pitch in place, protects it from wear and from the action of 
the elements; it also has considerable fire-retarding value. Slag is 
better than rounded gravel for moderately steep roofs, because be- 
sides having sufficient weight it has exceptional bonding power. 
But if the mineral coating material be too fine its holding power is 
lessened. If it be too large the stones may cause damage to the roof 
when it is walked upon and are more apt to roll off. Crushed 
material with rough, sharp edges has a much better holding power 
than rounded gravel. Sand or dirt mixed with the gravel is objec- 
tionable, as it tends to prevent the gravel from bedding itself in the 
pitch. Sometimes the sand mixes with the pitch, the resultant being 
more inert and liable to crack than the clean pitch. 

In the final mopping of a felt roof the effect is to get the maximum 
amount of coal-tar pitch coating which can be kept in place. The 
flatter the roof the greater the amount of pitch that can be used and 
the better the pitch and gravel will stay when put in place. 

The melting-point of the pitch should be varied to suit climatic 
conditions. This variation is easily- accomplished because it only 
depends upon the source of the tar, and the point to which the dis- 
tillation of the coal-tar is carried in the process. But the melting- 
point of pitch is not definite and in defining it for a particular pur- 
pose and locality a specification is advisable. The use of a pitch 


with a melting-point too high to allow satisfactory working and 
requiring the addition of a flux on the work, giving what is known 
as a " cut-back " pitch, should not be allowed. 

The best results are obtained when the slope of the roof is only 
enough to allow it to thoroughly drain. A method which gives good 
results on steeper roofs is the addition of some asphalt to the pitch 
which is used for the top coating. This must be carefully done, as an 
intimate mixture of the asphalt and coal-tar pitch is not easily 
obtained. Coal-tar pitch is often prepared for use on moderately 
steep slopes by the addition of some finely ground inert material, 
but this is liable to give uncertain results unless the mineral dust is 
thoroughly and uniformly mixed throughout the mass. Powdered 
slate and actinolite* are much used for this purpose. Portland 
cement and plaster of Paris are also used. 

In place of felt alone, for building up this membrane-roofing, 
treated jute or cotton fabric is sometimes alternated between plies. 
While a stronger membrane results no other advantage accrues to 
the roofing to counterbalance the increased cost thereof, even when 
the number of felt plies is reduced thereby. 

Where waterproofing and fireproofing are equally important, an 
asbestos roofing felt is often used. The asbestos, being a mineral, 
besides being fire-resistant, has the advantage that it will not decay. 
It is not as absorbent of the preservative though, as felt. This 
type of roofing is ordinarily applied only by the manufacturer. 
It usually consists of one or more plies of asbestos felt, with a 
strengthening material, such as jute or cotton fabric, in the center, 
and cemented together with asphaltic compounds. Here the reinforc- 
ing fabric is essential due to the extreme weakness of the asbestos 
felt. Roofs composed of this material usually do not need slag or 
gravel, thereby reducing the weight and presenting a clean, smooth 
finished surface. The absence of slag or gravel incidentally precludes 
the possibility of clogging down-spouts and gutters, which seems 
almost an unavoidable defect of all felt roofs with mineral 

Asbestos felt roofs of the built-up type are applied over boards 
as follows: First, a composite membrane composed of one untreated 
asbestos sheet and one treated sheet (usually combined at the 
factory) is laid on the roof boards, lapping and cementing, and 
nailing the sheets every 2 inches, with the untreated side down. 
This is followed with two more sheets of impregnated asbestos felt, 
placing these succeeding sheets so as to always break joints and 
* A calciUm-magnesium-iron mineral. 


having the next nailing in the center of; the sheet thereunder. All 
nails are on the under edge, protected by the asbestos and binder. 
Each sheet is mopped .its full width. 

Asbestos, felt roofing over concrete is laid the same way as over 
boards, except that usually three impregnated sheets are used as 
described. Sometimes the concrete is first coated with a liquid 
priming coat, making it possible for the hot bitumen to better stick 
to the concrete surface. 


To reduce cost and labor, and to meet some of the conditions 
wherein a built-up roof is not satisfactory, innumerable substitutes 
are made and sold extensively in the form of " ready " or " prepared " 
roofings. They are of special value for steep roofs and temporary 
structures. Ready roofings consist mainly of thick, heavy, specially 
treated rag or pulp and wool felt, covered on one or both sides with 
rather .tough bitumen, leaving a smooth or corrugated finish similar 
of prepared shingles (see. Fig. 34, A), and sometimes also surfaced 
with fine sand or grit (Fig. 34, B), or stone screenings (Fig. 34, C). 
The amount of surfacing material. that can be used is limited to the 
amount that can be successfully rolled on the felt. If the particles 
are too. large they may damage the felt in rolling. Ready roofings 
are also made. of one, two, or three plies of thin treated felt, bonded 
and surface coated with asphalt or coal-tar pitch in the factory, and 
applied as individual sheets in the field. Coal tar, however, is not 
considered the best material for a high-grade ready roofing. These 
and other varieties are made up in rolls of standard widths and 
weights, of one and two squares, accompanied by the nails and 
cement necessary to apply them. The standard width is 36 inches, 
and the standard weights are: 35 pounds for one ply, 45 pounds 
for two plies, and 55 pounds for three plies. However, there is no 
uniformity of practice among, the different manufacturers. In apply- 
ing these sheets they are usually laid in the direction of the width of 
the roof, overlapping from 2 to 6 inches, cemented with a bitumi- 
nous solution (usually some bitumen dissolved in a volatile oil), and 
nailed down with the nails,not more than 2 inches apart. The best 
type of nails are made;of 'No.l? gauge wire, with a cap made of cold- 
rolled hoop steel welded bt in the .factory. 

Prepared roofings are 'cheap, easily applied, and quite durable, 
but as a class, somewhat inferior to a first class built-up roof. The 
weakest points abo.ut ready roofing are the. narrow laps and the fact 




that usually a large part of the roof is covered with but one layer 
of the material, hence a single break will cause a leak. 

There are a great many varieties and qualities of ready roofing, 
the heavier varieties, in general, being more desirable. There are 
also many methods for holding them down against weather con- 
ditions. Fig. 35 shows ready roofing applied to a flat roof, lapped, 
and nailed down with metal cleats. So or similarly protected, 
these roofings are equally serviceable for flat and pitched roofs. 

Applying Ready Roofings. There are various ways of applying 
prepared roofing, depending on whether utility or architectural 
effects are most desirable. To secure the latter effect, the roofing 
felt should be applied with the pitch of the roof, the joints and roofing 
nails being covered with a molded batten of wood, about f inch by 1 J 
inches. The under side of this batten should be rabbeted to a depth 
of | inch to make room for the heads of the roofing nails. The rabbet 
should be filled with a plastic cement, such as accompanies the roof- 
ing, and the latter then securely nailed. Roofs so prepared have the 
appearance of a standing-seam tin roof. The most common method 
of applying ready roofings, however, is as follows: 

A good foundation for the roofing is very important. Hence the 
practice advised for applying sheathing boards in connection with 
shingle roofs is directly applicable here. Also in the case of cracks 
or knot holes, in the boards it is good practice to tack pieces of 
tin over them. If the weather is warm, the ready roofing should be 
unrolled and allowed to lie exposed to the sun and air to thoroughly 
flatten out, and stretched before being nailed down, otherwise it 
may wrinkle or buckle. If the weather is cold, the roofing should be 
kept in a warm room just before it is unrolled and used, taking special 
care to stretch it out thoroughly and nailing it in place while still 
warm. Sheets should not be cut when spread on top of those 
already laid, nor should the roofing be torn, but always cut with a 
sharp knife to insure straight edges. For very steep roofs it is often 
better to cut the desired lengths on the floor. It is very important 
to plan the work in advance as far as possible, particularly at flash- 
ings, around vertical walls, chimneys or any other projections from 
the roof and at laps or joints. 

The roofing material should always be laid so as to have the 
seams or laps run parallel with the sheathing boards, as this arrange- 
ment will insure a uniform and even nailing surface for securing it. 
Great care is required to see that the roofing laps over solid sheathing 
boards, and not over a joint or crack. If a lap, on account of the 
position of a previous sheet, should occur so as to bring the nailing 




r ,* ' t .-..--.. ~ ->..- .. 

points directly over a joint or a crack in the sheathing boards, 
the next sheet should be shifted an inch or two so as to avoid 
the crack. 

Upon a flat roof the sheets are laid with the slope of the roof 
when the sheathing boards run that way. Beginning at the left, 
the first sheet is unrolled and placed so as to permit about 3 inches 
to extend up against the fire wall, or in the event that the roofing is 
turned over sheathing boards at the side, 1 or 2 inches should be 
allowed for this purpose, and from 1J to 2 inches at the eaves or 
end'^of the sheet. This sheet must be carefully adjusted and flattened 
into! position, folding the sheet carefully where it projects against 
the ifire wall so as to make a good corner without breaking the felt. 
It is temporarily secured in place by driving a few nails along its 
edg and end; then the next sheet is unrolled, allowing it to overlap 
at (east 2 inches, being careful to obtain a uniform lap along the 
entire seam. After this second sheet is carefully adjusted and 
flattened out, it should be nailed directly over the 2-inch lap, placing 
the nails within J inch of its edge. This is repeated until the entire 
roof is covered. 

Making watertight flashings against fire walls, is equally as 
important as making watertight joints between plies and laps in 
the! various roofing materials. This is discussed in the following 



'An important part of the construction of roofs and roof parapet 
walls on large brick or concrete buildings is the flashing. Flashing 
may be defined as a piece of metal or waterproof material used to 
keep water from penetrating the joints principally between a fire 
wall or projection through the roof of a building or other structure. 
Its 'efficient location and application as well as the selection of the 
best material are matters that require careful study. For general 
work most roofers can supply and apply flashings meeting all re- 

The vital part of a brick parapet wall is the inner side, which 
heretofore was made up of common brick laid up in ordinary lime 
mortar. As a result, and owing to the freezing of the brick above 
the roof flashing due to saturation from snow or rain many brick 
parapet walls, after a few years became a crumbling mass. In 
consequence the flashing became loosened and water percolated 
through the joints to the detriment of the interior, To avoid the 


above condition it is now the practice to build the inner side of the 
brick parapets of hard burned vitrified brick laid up. in cement 
mortar and covering the top with a waterproof Doping;-, ; In addi- 
tion to this the roofing material is sometimes carried": up to the 
under side of the coping. But a common procedure .Is. ' to take 
one or more strips of felt or ready roofing about 12 inches wide, 
folded in the center and fitted into angles at fire walls, chimneys, 
etc., so that 6 inches project up these surfaces and 6 inches lap over 
the roofing. These strips are fastened (if more than one is used 
as on composition roofs) with a row of nails at the upper edge of the 
upper strip by driving them into the mortar joints between the 
bricks, and securing the lower edges (if ready roofing is being applied) 
with a row of nails applied similar to an ordinary lap, or by mopping 
with pitch or asphalt (if composition roofing is applied) and com- 
pletely coating the surface of the flashing strip as is ordinarily done 
on the roofing proper. All flashings on brick walls, etc., should be 
counter flashed with metal so as to prevent water from eventually 
working in behind them. These counter flashings must be thoroughly 
secured in a mortar joint above the roof flashings and turned down 
over the seam for at least 4 inches. For buildings subjected to 
gases and fumes, saturated felt properly coated with good asphalt 
or pitch preparations will give good results. For buildings located 
outside of industrial centers, non-corrosive metal flashings give very 
good results. A very efficient means of fastening both the flashing 
and counter flashing is shown in detail (applicable both for com- 
position and ready roofing at parapets) in Fig. 36. This detail, 
recommended as good practice by the American Railway Engineering 
Association,* makes use of a 2- by 4-inch timber with one edge 
beveled, laid continuous in the parapet at the proper height in place 
of a stretcher course of brick. This serves as a nailing strip for a 
light wooden strip holding the flashing and counter flashing in place. 
After placing the flashing the slot is completely sealed up with cement 
grout or roofing cement. 

For the proper flashing of concrete parapet walls the detail shown 
in Fig. 36 can be recommended. * A 2- by 4-inch piece of lumber is 
ripped on the diagonal as shown and then placed in the forms at the 
desired height, the upper strip being securely nailed thereto, so as to 
insure its removal when forms are taken down, while the lower piece 
is just tacked to forms (from outside) with wires or nails driven into 
it as shown to anchor it to the concrete. The flashing and counter 
flashing are then placed in the same manner as for brick walls. 
* Concrete. Vol. 9, No. 6, December, 1916, p. 197. 


An ingenious and inexpensive flashing is shown in Fig. 37. The 
metal lock referred to in the diagram is of galvanized sheet iron, 
and acts as the backbone for the flashing, which may be made of 
ordinary felt or strips of prepared-roofing felt, these often being 
substituted for the more expensive all-metal flashings. 

2 'x 4 (Continuous 1 ) 

Seal of Cement Grout 
or Roofing Cement 



FIG. 36. Flashing Details. 


The function of impervious roofing is to shed the rainwater so 
that none finds entrance into the building. On small and unim- 
portant structures, rainwater is allowed to drip off the eaves, often 
discoloring the walls. On most structures, however, both large and 
small, provision is made for taking care of the drip by providing 
gutters directly under the eaves, or other roof plane, and in the 
valleys of the roof. The most modern practice is to slope the roofs 
of buildings so as to provide drainage in the direction of the center 
of the structure, where the gutters and conductors are arranged for 
easy access. This arrangement avoids marring the architectural 
effect of the facade. Fig. 38 shows typical arrangements of metal 
gutters and conductors, for mill and factory buildings. 



Portion of lock 
before hammered 

Metal lock is hammered to 
ready-roofing flashing-strip* 

gripping same by means of 
clinch holes in the lock 

Joints are filled with 
cement mortar or 
flexible cement. 

with pitch 
or asphalt. 

FIG. 37. Showing Method of Using Felt in Place of Metal Flashings. (Metal 
Lock Illustrated is Patented.) 


FIG. 38. Eave and Valley Gutters of Galvanized Iron or Steel. (American 
Bridge Co.'s Standards.) 


Gutters should be sloped not less than 1 inch in 15 feet, and 
if made of sheet iron, or steel, should preferably be galvanized than 
tinned because the latter variety corrodes more easily around an 
abrasion or other slight damage. The gutters and leaders, or con- 
ductors, made of these metals should be of No. 22 to 20 gauge 
(18 to 22 ounces per square foot). On the better class of structures, 
gutters and conductors are usually made of copper, in which case 
the metal used varies in weight, from 14 to 20 ounces per square foot. 
Hanging gutters are frequently made of considerable length; there- 
fore they should be strongly built, as otherwise they are liable to 
deflect from a uniform grade. Simple and inexpensive gutters are 
often made by fastening a strip of wood, of appropriate size, close 
to the end of the eave of the roof and sloping towards the conductor. 
This strip runs along the entire length of the eave, and is covered 
by the material used for the roofing, or by sheet metal. This 
practice, however, is mainly resorted to on low buildings, such as 
mill buildings and small-town railroad stations. 


Definition, Use and Varieties cf Functional Roofings. Functional 
roofings consist of such materials as both waterproof and roof the 
uppermost part of a structure; that is, they are compositive and 
include all those not covered by the previous types of roofings. 
Most of the functional roofings are of recent origin and have a 
limited use because they are usually adapted to special types or 
temporary structures. They are for the most part though, efficient 
and often inexpensive. The following are examples of functional 

Corrugated or crimped galvanized sheet iron (see Fig. 39) and 
asbestos-covered corrugated sheet iron (see Fig. 40). These are 
often used for the roofs of freight cars and small mill buildings; 
also metal shingles, which have a limited use on railroad structures. 
In general, however, steel or impure iron materials are avoided, 
especially on important structures, even though these materials are 
protected, because of the necessity of frequent repair or renewals. 
The structural-composite roofing shown in Fig. 41 is serviceable 
for train sheds, depots, and large mill buildings. Heavy cotton 
canvas, sometimes treated with a preservative, but always painted, 
is extensively used as roofing for freight and passenger railroad 
cars and on decks of ferry boats. Glass roofings, for which there 
are many methods of making watertight joints (two of which are 



11 " " 

11 ,. " ,. " " 

FIG. 39. Corrugated Galvanized-iron Roofing, Showing Method of Lapping 

and Flashing. 

FIG. 40. Asbestos-covered Corrugated Roofing. 



FIG. 41. Structural-composite Roofing. 

[ Purlin Clip 


"^ h^ 

\ \ /Condensation 

i)\ / Gutter 

-Insulation and 
Rust Proofing 

Purlin Clip | 

FIG. 42. Two Types of Watertight Joints in Puttyless Glass Roofing. (Patented.) 



shown in Fig. 42) are well-adapted for depots and general skylights 
of -buildings; also for roofs of buildings used in the production of 
motion pictures. Roofs of many factory buildings and all concrete 
buildings are made either of reinforced concrete or, to insure better 
watertightness, have an integral waterproofing compound added to 
the concrete. 

The method of applying functional roofings depends on the 
material and also somewhat on the structure. Sheet and corrugated 
galvanized iron are usually nailed down to the purlins and lapped 
both lengthwise and crosswise as shown in Fig. 43, A. Sometimes 

FIG. 43. 

A. Methods of Nailing Down Corrugated Sheet Iron on Roofs and Sidings. 

B. Methods of Applying Sheet or Corrugated Roofing to Roof Framework. 

small iron cleats are riveted to the sheets which hook on to angle 
irons screwed on to the purlins or roof frame work. Fig. 43, B, 
shows several methods in common use. The former method pro- 
duces a more durable and watertight roof. . 

The slab type of functional roofing is usually made so as to lap 
over each other and fit into prepared grooves. The joints are usually 
made watertight with an adhesive, elastic compound. 

A roof built of concrete blocks or blocks of any other material 
will not of itself be watertight because of the many joints; such 
roofs must first be waterproofed usually with a membranous roofing 
material, hence these materials cannot be classed as functional 


Function and Properties of Expansion Joints. Expansion joints 
constitute one of the basic causes contributing to the difficulty of 
making masonry structures watertight. When masonry is to be 
waterproofed its expansion joints must be so made that water cannot 
pass through them. This is usually accomplished either by some 
form of tongue and groove, by a bent cutoff plate, by gaskets, and 
so forth, in endless variety. Designers usually include some form 
of bitumen or other sticky, plastic material as a joint filler. 

To devise a joint that will remain tight under all conditions of 
weather and stress is exceedingly difficult. Most failures of water- 
proofing are due to the lack of joints, to joints not placed where the 
tensile stress is large, to narrow joints, or to joints which do not 
remain watertight. In a great many cases if an adequate number of 
good watertight joints were provided no other waterproofing would 
be required. Concrete and other masonry can nearly always be 
made as impervious as necessary between cracks, and therefore the 
waterproofing of a structure is often a question of waterproofing 
its joints. Hence, we shall investigate, (1) the methods used for 
the proper provision for expansion and contraction in concrete or 
other masonry; and (2) the methods used for proper waterproofing 
of the joints. 

Expansion joints are used in structures to allow the masonry to 
expand and contract freely with changing temperature, and to per- 
mit other necessary, small, internal movements and readjustments. 
Expansion joints are, in fact, simply cracks built into the masonry 
to anticipate or take the place of the internal cracks and breaks. 
A sufficient number of these joints must be provided to avoid dis- 
figuring the masonry with unsightly cracks (see Fig. 124). The 
following instance demonstrates the commonest way that cracks 
occur in masonry. Structural materials have a varying coefficient 
of expansion* (see Table XXX). 

* The coefficient of expansion for. any material is the factor which expresses 
the change per unit of length for each degree of temperature. 



The coefficient of expansion for concrete is variously assumed 
as .0000055 or .0000065 per deg. Fahr. (about | inch in 100 feet 
for each 15 deg. Fahr.). These coefficients vary somewhat with 
different proportions and kinds of aggregate in the concrete. Assum- 
ing for concrete a modulus of elasticity of 2,000,000 pounds per 
square inch and an ultimate tensile strength of 200 pounds per square 
inch, a distortion, in tension, of 0.0001 inch will fracture it.* Fifteen 
degrees Fahr. drop in temperature produces this change in length 
and is thus just sufficient to break restrained concrete. 

Monolithic Construction Obviates Expansion Joints. To avoid 
the use of expansion joints, small structures are often built as mono- 
liths for which the waterproofing is fairly simple. Larger structures 
can be built monolithic by imbedding sufficient steel in the concrete 
so that the concrete is not stressed beyond its breaking strength. 

The elimination of joints by this method may be carried a step 
further. Reinforcing metal can be placed the whole length of a 
structure of any size or of a structure whose ends are restrained. 
But in this case the function of the steel is quite different from 
ordinary reinforcing steel. Fifteen degrees drop in temperature will 
break the concrete as if the steel was not present. But the intro- 
duction of the steel merely causes the cracks to be smaller and 
closer together. Steel has about the same coefficient of expansion 
as concrete. But the ratio of ultimate tensile strength to modulus 
of elasticity is so much greater with steel than with concrete that, 
while concrete is broken by a 15 deg. Fahr. drop in temperature, 
a drop of 100 degrees only stresses steel to its safe working stress, 
a drop of 175 degrees to its yield point, and no temperature change 
whatever is able to break it. A moderate amount of steel makes 
the cracks so small and close together that they are unnoticeable. 
The actual quantity of steel, which can be readily computed, varies 
between .1 per cent and .3 per cent of the cross-sectional area 
of the concrete depending on climate and local conditions, as, 
for instance, whether the structure is above or below ground. 
None the less it must be borne in mind that the concrete 
is fractured and that therefore water will find its way through, 
particularly if under a head. The total cross-section of the cracks 
will be about the same in both cases, but the capillary and fluid 
friction through the mass will considerably reduce the permeability 
of the concrete, and eventually these minute cracks may be closed up 
with silt, thus making the structure completely watertight. 

* Modulus of elasticity equals stress divided by deformation; using these 
values the deformation is 0.0001. 


Design and Spacing of Expansion Joints. The width of a joint 
controls the longitudinal movement of each section, and, hence, 
controls the movement of the entire structure. Therefore expansion 
joints should be large enough to accommodate any movement that 
may occur and spaced sufficiently close together to eliminate all other 
cracks or joints. In other words, the joints must be so spaced that 
under all conditions of temperature change, loading, vibration, or 
foundation settlement, the masonry between the joints will be a 
single monolith. The proper location and design of these joints 
require forethought, experience and good judgment. 

To design a joint, the change in length is computed for the tem- 
perature variation of the particular climate. This is increased as 
needed to allow for other movements, plus a small amount as a fac- 
tor of safety. The spacing of the joints is determined by computing 
the frictional resistance to movement between the masonry surfaces. 
The joints must be so close together that the stress resulting from this 
friction is within the safe tensile strength of the masonry. Stresses 
due to other causes must of course be computed and combined with 
the friction stress. 

Joints may be located at intervals of from 25 to 50 feet, although 
under favorable conditions and sufficient reinforcement, larger 
sections may be used. But the larger the section between joints, 
the wider should the joint be made. For restrained structures and 
large gravity retaining walls, the maximum distance that joints 
should be spaced is 50 feet. Concrete walls which are less than 3 or 
4 feet in thickness, and subject to about 60 deg. Fahr. seasonal 
change of temperature, should have joints spaced about 30 feet apart. 

Joints in Brick Masonry. Expansion joints in brick masonry 
are rarely employed, but the joints between the bricks require care- 
ful attention where impervious walls are necessary, as for instance, 
in residences. 

The mortar in the joints of brick masonry is usually deficient in 
density and hence is quite absorbent and more or less permeable. 
Often for the sake of enhancing the appearance of a residence the 
mortar is raked out of the joints for a depth varying between | and 1 
inch and left so. This is poor practice because very little mortar 
may remain near the front face of the brick to prevent the percolation 
of water especially when aided by a driving rain. This often happens, 
resulting in damp and wet interiors. Where it is proposed to use 
this type of joint in the masonry, then, to make these joints imper- 
vious, half the raked-out space should be filled with a pointing 
mortar. The pointing material may be either neat cement or mortar 


composed of Portland cement and sand in equal proportions, mixed 
with enough water to form a stiff paste. This paste should be 
tamped in with a metal calking tool and the joint facings can then 
be finished according to one of the pointings shown in Fig. 44. 

Where this practice is not resorted to, i.e., where neither raking 
nor special joint mortar are employed, and where dry and damp- 
proof interiors are desired (assuming that the best grade of bricks 
were used) then the mortar joint' proper, madeas the work progressed, 
should also be pointed as illustrated. 

The Slip-tongue and Plane-of-weak-bond Joints. The types of 
expansion joints used in practice are almost as varied as the types of 
masonry structures built nowadays. The simplest expansion joint 
for concrete dams, walls, etc., is a plane of weak bond in the structure, 


FIG. 44. Types of Mortar Joints Used for Appearance and Utility. 

made by building one section first and coating it with bitumen or 
other compound, or nailing to it one or more plies of treated felt, 
sometimes bonded with bitumen, against which the concrete of the 
second section is poured. 

That it is necessary to create a plane of weak bond in the structure, 
by interposing some form of coating or sheeting between the joints 
of all sections, is evident from the fact that the separation at the 
joints is not otherwise uniformly perfect. When joints are formed 
without interposing any sheetings or other separating material, 
then by pouring one section after the adjoining section has set, no 
adhesion of any large amount would be expected under these con- 
ditions; yet it often happens that there is a strong enough bond to 
break through solid concrete alongside the joint. This is evidenced 
by the many meandering cracks (other than shrinkage cracks) often 
seen close to and paralleling the V-groove formed in the face of 
concrete walls at joints, 



Another phase of the joint problem worth noting is the protection 
of horizontal joints. In the construction of concrete walls, abut- 
ments, etc., almost sole attention is given to vertical expansion 
joints and their protection against the seepage of water through 
them. Little if any real attention is paid to horizontal joints, and 
yet it is these joints that are mostly responsible for discoloration 
(see Fig. 2) and equally responsible for leakage in these and other 
structures. Whether the horizontal joint be a days- work joint or a 
construction joint, its existence is a source of danger to the unity 
of the structure from the waterproofing point of view, and should be 
cared for as effectively as vertical joints. Fig. 45 shows an effective 

Lap Joint- Strips 
joined by heatin 


Expansion Joint, 








^ Asphalt Strip Baffle^ 
^Construction Joints * x M x 8' 


^^Viscous Bituminous Compound 


r -r.-;^:^- :^-^:t-- :-:?*: :*.-: 



""Joint Coated with Paraffine 

FIG. 45. Location of Horizontal Baffle Joints in Walls and Tanks. 

method of waterproofing horizontal joints. Its efficiency is some- 
times doubtful because the slip tongue, which is generally made of 
sheet iron, and though sometimes painted with a preserving com- 
pound, too often corrodes and vitiates its function. What should be 
used as a slip tongue to avoid such defects is a non-corrosive material 
and such may be made of tough elastic asphalt strips similar to the 
precast expansion joint fillers used in concrete road construction. 
Fig. 48 shows such a scheme of protecting horizontal joints in which 
the barrier is placed on the finished concrete in the form of a strip, 
before the new concrete is deposited. 

Illustrations of Expansion Joints. One requisite for all forms 
of expansion joints is that they be so constructed as to retain the 


joint filler (which alone waterproofs the joints) as long as the struc- 
ture lasts. A second requisite is that the joint filler itself retain its 
properties, and last equally as long, or allow of replacement at 
definite intervals. The first requisite will be well provided for by 
adhering to the basic type of joints shown in Fig. 46, modified, of 
course, to conform to any special requirement. The second requisite 
will be satisfied by any material which does not lose its " body " 
or substantial character, adhesiveness and elasticity, at least not 
rapidly, and is not affected by water. Such compounds are dis- 
cussed further on in this chapter. 

Front of Walk 


^ M 


rr~'. . '*-'* ' *V- ' ' 

/.:-V::v.:.:d. : ..ij.;. : 


x-Joint Filler 

Joint Filler 

1 Stiiieifc?d : ^ah?i ; 

D E 

FIG. 46. Basic Types of Waterproofed Expansion Joints. 

Fig. 47 (A, B, C and D) is taken from a report by the Committee 
on Buildings and Structures of the American Electrical Railway 
Engineers Association. These joints have several interesting 
features which are evident and self-explanatory. 

Fig. 48 illustrates a method of waterproofing horizontal and 
vertical joints in concrete walls; the former by means of gaskets or 
strips of fabric thickly coated with a bituminous material ; the latter 
by means of rolls of the same material fitted in a prepared groove of 
one section and surrounded by the concrete as poured for the next 



J " 










" Separation made! 
by insertion of 

. Stone laid 
.dry packed 
/against wall 1 
xfor 3'0'at each 
joint and 
weep hole. 


Top of Platform 



FIG. 47. Typical Forms of Waterproofed Expansion Joints Used for Various 



section, with the rest of the joint between sections filled with several 
plies of treated felt. It is possible to make very efficient expansion 
joints in this manner, provided the compound used for treating the 
fabric, of which the gaskets and rolls are made, remains tacky and 

Back of Wall 








Horizontal Joint/ 
Filler. 2 Layers 

^ v- 

^Vertical Joint Filler, 
Tight Roll, 3 Dia. 



3 Ply Treated Felt 


FIG. 48. Horizontal Waterproof Baffle, and Vertical Expansion Joint and Joint 
Filler Used on Concrete Retaining Wall of the Brighton Beach Line, B.R.T. 
Railroad System, Brooklyn, New York. 

adheres to the concrete when set, and elastic, so that it " gives " 
when contraction and expansion take place. 

Fig. 49 shows a horizontal joint for a concrete floor. This joint 
is waterproofed by means of a copper V-joint anchored and filled 
with a joint roll, consisting of treated fabric wound tightly on itself 
and covered with some tenacious and elastic compound, which when 



the joint contracts, forms a bulb upward, and on expansion forms a 
groove. But this operation is only possible when the joint filler 
adheres tenaciously to the sides of the joint. 


FIG. 49. Type of Waterproofed Expansion Joint Used on Public Service Railway 
Terminal, Newark, N. J. 

Fig. 50 is a form of expansion joint advocated for solid bridge 
floors, and patented by Mr. A. H. Rhett, Engineer. Fig. 51 (A and B) 
is from the Waterproofing Specifications of the Chicago, Milwaukee 
and St. Paul Railway, and shows their method of waterproofing 

j.-jy.;-:c--:ii:-'^:-.:p.-:w-- j [\-~.-m\o > o *v:-X2&-B-ff.W.&Wt^. 

FIG. 50. Waterproofed Expansion Joint for Solid Floor Bridge. (Patented.) 

bridge floor expansion joints. This method consists in applying 
two continuous strips of treated felt, 36 inches wide, over the expan- 
sion joints, being careful to see that no bitumen gets between or 
under the two strips of treated felt. Then the top strip is mopped 
with hot bitumen and the waterproofing proper carried over the top 
of the felt as if no joint existed. 


The joint shown in Fig. 52, A, is a vertical square or rectangular 
recess filled with plastic clay. The clay must be of the best quality, 
placed while wet and rammed absolutely solid into place, otherwise 
it will not cohere into a unit mass. Fig. 52, B, shows tne rectangular 
and triangular tongue-and-groove types of joints commonly used 
for small masonry bridges and abutments, parapet walls and retain- 

2 Layers of Tar Paper 


Expanded Metal- 

Round off corners of slab 

2 Layers of Tar Paper 




FIG. 51. "Unfilled" Type of Waterproofed Expansion Joint. 

ing walls. They form merely a weak bond in the structure, but 
permit lateral movement and so prevent disalignment. However, 
unless some barrier, as a bituminous sheet or membrane, is inter- 
posed, water will readily seep through these joints. 

Fig. 53 shows a reinforced tongue-and-groove joint successfully 
used on the Compton Hill Reservoir, St. Louis, Missouri.* The 
* Engineering News, December 23, 1915, Vol. 74. 



joint was filled with treated felt and pitch binder as each section was 
built up. Fig. 54 shows an all-adaptable form of joint waterproofed 
with a soft asphalt contained in a copper bulb the imbedded portion 
of which is perforated so as to bond more securely. Fig. 123 is an 
efficient form of joint used by the Delaware, Lackawanna & 
Western R. R. on two of its viaducts. 

Cutoffs in Expansion Joints. Water should not be allowed to 
enter expansion joints; but if this be inevitable, then it is best to 
use some form of cutoff, near one face of the structure, and to provide 
proper drainage within the structure. Copper, tin, galvanized iron, 
lead and zinc sheeting are often used as cutoffs in expansion joints, 

A Clay 

Pi IS 

fe^v lliSil 

- ^| 

^-M*^*^K ; vV 

' } -."^--^- : ' 

FIG. 52. 

A. Rectangular Recess in Expansion Joint, Filled with Plastic Clay. 

B. Rectangular and Triangular Tongue-and-groove Expansion Joints. 

and all serve their purpose very well, but the copper sheeting best of 
all. There are two types of cutoffs, known as the internal and exter- 
nal. One of the best illustrations of modern practice showing the 
use of the internal type of cutoff is in the expansion joints of the 
Kensico Dam on the Catskill Aqueduct of New York City. 

The expansion joints in this dam contain a strip of copper placed 
across each joint near the upstream face to cut off leakage (see Fig. 
55, B). This cutoff was constructed in the following manner: 
A portion of the strip was placed in a groove in the vertical face 
of the masonry forming one side of the expansion joint, and sur- 
rounded with concrete or mortar, allowing the remainder of the 
strip to project, as shown in detail in Fig. 55, A. 



O % 15 c. to c. 

/./'.'? -."Expansion Joint 


^. H Bent Bars 
.'-.- 12 "c. toe. 


FIG. 53. Detail of Reinforced Expansion Joint for Retaining Walls. 

Sidewalk or 
Road way Slab \ 


:.: - ::.'. : : .'.' ip'orta pn.'<^'.-. ': <{ 

: '&/.:i&y$$&ft?ty&s. : : 
.'.':' : .:;.; .':j>:.-.'-';'- : -'-" '.'.":' \ 

^^ ; ^::-'/-^:&':- : -:& 

P13lf ; ^ lR 


FIG. 54. Type of Waterproofed Expansion Joint Used on the Brooklyn-Brighton 
Viaduct, Cleveland, Ohio. 




After the concrete or mortar in the groove had set, the central 
part of the projecting strip and the portions of the vertical faces of 
the masonry against which it rests were coated with hot paraffin or 
other suitable substance to prevent the adhesion of the strip to 
the concrete where it crosses the expansion joint. Concrete was 
then placed and carefully rammed around the projecting strip on 
the other side of the joint, care being taken to thoroughly clean 
the uncoated portion of the strip before placing the concrete. The 
strips were built up in sections, riveted together with copper rivets. 

The operation of this cutoff is as follows: As the masonry 
contracts, the expansion joint is, of course, enlarged. Water enter- 
ing at D (Fig. 55, C) will proceed as far as the junction of the copper 
strip E and the masonry. From there the water cannot get around 

Exterior of Pipe Wall'" 

FIG. 56. Expansion Joint with Internal Cut-off Used in Reinforced Concrete 
Waterpipe. (Patented.) 

to the other junction at F. Hence, it remains there and freezes 
when cold weather sets in. The effect of this freezing and the con- 
sequent thawing is cumulative upon the structure in that when 
ice forms the water expands, exerting a force in the same direction 
as the contraction of the masonry, caused by the lowering of the 
temperature. On the other hand, when thawing sets in the mobility 
of the water returns and the masonry expands unimpeded. The 
copper strip being placed near the upstream face keeps the rest of 
the joint practically dry. 

The internal cutoff is not limited only to large and massive struc- 
tures, but may be and has been used very successfully on reinforced 
concrete pipes for conveying water even under pressure. These 
pipes are usually made in small lengths, 3 to 10 feet, of scientifically 
graded aggregate mixed in about the following proportions, 1 : 1J : 2J. 
The connection between lengths is made in the form of an expansion 
joint, such as shown in Fig. 56, which is patented. This expansion 



joint has an internal cutoff in the form of a strip of soft copper cast 
in the spigot end and passing clear around the pipe, being crimped 
as shown to permit the longitudinal movement of the sections. 
The other end is set in mortar rammed into the joint from the inside, 
and protected with a coat of neat cement, as shown. The joints 
are made free to open and close by the application to the face of the 
spigots of a bituminous paint. 

-Asphalt Block Paving 

Steel Plate 

Tar Paper. 

Vitrified Pipe 
if required' 

-Vitrified Pipe 

FIG. 57. Detail of Expansion Joint for Bridge Floor. 

An expansion joint in which the water is not only prevented from 
entering, but is quickly drained off if it should enter, is shown in 
Fig. 57. This was also used on work connected with the Catskill 
Aqueduct in New York City. Fig. 58 shows another joint of this 
type (sliding expansion joint) unique in its design, adapted to and 
used on the road slabs and sidewalks of the concrete arch bridge in 
City, Mo.* A similar joint, modified so that sliding is 
* Engineering Record, Vol. 75, No. 3, January 20, 1907, p. 109. 


obtained by means of short pieces of old rails imbedded in the base 
of slabs and top of piers and abutments, was used on a double- 
track concrete railroad bridge over the Oka w River in Illinois.* 

The external cutoff is much used by railroad engineers for retain- 
ing walls and deserves a wider application than it at present enjoys. 
This cutoff usually consists of a fold formed by laying the membrane 

1 Layer Paraffin Treated 

Felt, between 2 Layers 

of Tarred Felt 

Drainage Groove 

l"wlde, 2 deep, 

Full Length ol Plates 


Paint under surface with hot asphalt 

x %' Bar 2Vc. to c. 
--Drainage Groove 


FIG. 58. Road Slab and Sidewalk Waterproofed Expansion Joints Used in 
Floor of Concrete Arch Bridge over the Blue River, Swope Park, Kansas 
City, Mo. 

of whatever material is being used for the waterproofing, over a 
1-inch pipe at the joint in the concrete to allow for the expansion 
in the structure. The pipe is removed after the mat is completed. 
This mat is then covered with a protective coat of mortar or concrete, 
and sometimes with mastic. The external cutoff type of expansion 
>int shown in Fig. 59 was designed by H. J. Finebaum, engineer, 
* Engineering News-Record, Vol. 80, No. 8, February 21, 1918. 



and used on the new Hill-to-Hill bridge at Bethlehem, Penn.* It 
consists of two pieces of copper held in the concrete by lugs made by 
bending back the split ends of each piece and placed on each side 
of the joint with one end projecting through a groove in the con- 
crete beyond the inside face of the wall. These protruding ends 
are then bent over to hold a copper flashing piece across the joint 
between the sections of the wall. The flashing and straps are then 

No. It (Am. Gage) 
Soft-rolled Copper 
Straps, spaced. 
2 ft. c. to <r. 





of Fabric, contii 
at Expansion Joint 


No. 16 (Am. Gage) 
Soft-rolled Copper 

FIG. 59. An External Cut-off Type of Expansion Joint Used on the new Hill- 
to-Hill Bridge at Bethlehem, Penn. 

bound together, as shown, with the waterproofing fabric, against 
which the fill is placed. A thin masonry protective cover would be 
of advantage to the waterproofing fabric. In place of the copper 
straps the grooves might be' filled with mortar with better assurance 
of watertightness. 

Physical-acting Expansion Joint Fillers. Various materials are 
needed for filling expansion joints such as those considered above, 
* Engineering News-Record, Vol. 80, No. 8, February 21, 1918. 


and their properties must differ in accordance with the uses they 
are put to. 

There are on the market numerous expansion-joint fillers, but 
comparatively few possess all of the requisite properties for such a 
material. The essential properties are (1) to be chemically unaf- 
fected by the elements; (2) to completely fill the joints at all tem- 
peratures; (3) to constantly adhere to the two sides of the joint; 
(4) to be elastic, plastic and cohesive at climatic temperatures. 

As with many waterproofing materials so with many expansion- 
joint fillers, their composition is usually kept secret and carefully 
guarded, even from the purchaser. Therefore the only assurance 
one has of obtaining the right materials is the selling companies 7 
guarantee; or else the architect, engineer or contractor must resort 
to chemical analyses and physical tests, and though these tests are 
quite expensive, it is the safest way. On large engineering work 
this is very important and on building construction quite essential. 

In this connection it is of material interest to know that the 
chief cause of failure of joint fillers is loss of their sticky condition. 
This occurs for the following reasons: (1) Evaporation of solvents 
with the consequent hardening of the material; (2) loss of light oils 
due to capillary action with the consequent decrease in volume of 
the material ; (3) leading on of water-soluble material with the conse- 
quent porosity of the joint fillers; (4) chemically unstable material 
with the consequent decay of the joint filler. A material that is 
immune, at least for several years, from the ravages of these four 
agents makes an ideal joint filler. 

It is common knowledge that such materials as tar compounds 
and blown asphalts* are extensively used and make good expansion 
joint fillers for many purposes. But their indiscriminate use in the 
past was followed by many failures. Investigation beforehand 
would have obviated these disappointments. It would have dis- 
closed the fact that many, tar compounds (made for this purpose) 
leach out all too soon, and that blown asphalts are but short-lived 
when exposed to the elements. Various putties are used as joint 
fillers, but unless the liquid part is of such nature and consistency 
that it will not evaporate or be absorbed, these mixtures will harden 
and shrink, as will also those containing animal and vegetable 
materials. Hence the necessity for thorough testing of these 

* Refined asphalts acted upon by steam or air infused through its mass, which 
process produces a certain amount of oxidation in the asphalt, resulting in greater 
toughness of the product. 


A commonly used joint filler for joints between steel and con- 
crete (such joints usually being shaped like a " V," or sometimes 
rectangular) is a good grade of medium hard refined asphalt, mixed 
with from 5 to 10 per cent of grahamite, depending upon the melting- 
point desired for the final product. Such a mixture is tough, rub- 
bery and durable. At ordinary temperatures it is hard, but elastic. 
In applying this compound, it must be melted and poured into or 
mopped over the joints. 

Bituminous mastics are also much used for filling V-joints and 
for roof flashings with good results. These are usually made of 
medium-consistency coal-tar pitch or asphalt, mixed with about 20 
per cent of cement or limestone dust and asbestos. A mixture of 
about 45 per cent pine-tar pitch, 30 per cent of petroleum oil and 25 
per cent of fiber asbestos, is another extensively used filler for the 
same purpose. 

For certain types of concrete structures such as retaining and 
abutment walls, a mixture of clay and oil in various proportions is 
sometimes used as an expansion joint filler. The vertical joint in 
these structures is usually a plane of weak-bond with an enlarged 
space near the back of the wall shaped either as a rectangle or a 
triangle, and it is in this space that the joint filler is placed. The 
rest of the joint is closed up by the insertion of from one to three 
plies of treated felt, usually nailed to the face of the green concrete, 
and against which the new concrete is poured in forming the wall. 
The specific object of the joint filler is to intercept any percolation 
of water along the joint. 

Another joint filler usable for the same purpose and also for 
roof flashings, is composed of coal tar and powdered slate, in equal 
parts by weight. This mixture is applied cold with a trowel. 

The following compounds are very serviceable for filling hori- 
zontal joints in masonry because they remain elastic at comparatively 
low temperatures. However, all the bituminous fillers must be 
completely encased, as they have a constant though imperceptible, 
flowing tendency, and will actually flow away in time unless pre- 
vented. Many expansion-joint failures are traceable to the neglect 
of guarding against this. The degree of hardness for all bituminous 
joint fillers is based on climate and local conditions. Usually these 
types of joint fillers also require preheating and pouring during 

(1) A Mexican petroleum of about 18 deg. to 21 deg. Baume, 
refined so as to leave the heavier oils with the basic asphalt, then 
blown with compressed air until it has a melting-point of about 175 


deg. Fahr. (79.5 deg. Cent.) by the Cube-in-water method. To 
apply this material it must be heated and poured into, or mopped 
over, the joint. 

(2) Any good-grade refined asphalt of medium consistency to 
which is added about 5 per cent of stearin pitch and then boiled 
down to a dense consistency. This material is melted and poured 
into the joint when applied. 

(3) A blown refined Mexican asphalt mixed with about 3 per cent 
of gilsonite. The asphalt used in making this mixture should melt 
at about 140 deg. Fahr. (60 deg. Cent.) by the Cube-in-water method, 
and the mixture at about 175 deg. Fahr., by the same method. The 
kind of asphalt used governs the percentage of gilsonite to be added ; 
for example, a California asphalt would require about 10 per cent 
gilsonite. The amount also depends on the climate and local 
condition of the work. 

(4) A refined Trinidad asphalt having a melting-point of about 
200 deg. Fahr. by the Cube-in-water method, 88 per cent; gilsonite 7 
per cent; and grahamite 5 per cent. This mixture is especially ap- 
plicable to warm climates. 

(5) Any good-grade refined asphalt of medium consistency, 80 
per cent; linseed or China wood oil 10 per cent; and fine mineral 
matter (but no sand) 10 per cent. 

(6) A petroleum residuum in the form of a grease (petrolatum), 
for instance, and free of light or volatile oils makes one of the best 
joint fillers for V-joints of the type shown in Fig. 129. 

Chemical-acting Joint Fillers. Chemical joint fillers, that is, 
those compounds that become operative only after chemical action 
has proceeded in their substance while embedded in the joint, are 
not really expansion-joint fillers. But they are considered here 
because they are a means of making watertight joints in engineering 

For calking joints in steel and iron tunnels, especially those of 
the segmental type (see Fig. 136) , materials of the following formulas 
have been found serviceable. 

(1) Powdered pig iron, mixed with half as much lime, a quarter 
as much of powdered sand, and about one-eighth as much of salam- 
moniac. This gives a hard, waterproof, joint filler. 

(2) Eighty parts fine iron borings, one part salammoniac, two 
parts flour of sulphur, all by weight and mixed to a paste. This 
mixture forms a quick-setting joint filler.* 

(3) The following mixture is a slow-setting joint filler: Two 

* Molesworth's Pocket Book of Engineering. 


hundred parts fine iron borings, two parts salammoniac, one part 
flour of sulphur, all by weight and mixed to a paste. This is prefer- 
able to the former, if the joint is not to be put into use immediately. 

(4) A rust joint can be made by mixing ten parts of iron filings 
and three parts of chloride of lime to a paste with water. This 
material, when applied to the joint, will harden in about twelve hours. 

(5) For some time past steel joints have been made' watertight 
by the application of a paste composed of powdered pig iron and 
water only. But an accelerative oxidizing agent is now usually 
added and preferred. 

The joints of steel tanks and all manner of steel and iron con- 
struction where rigidity is practically a property of the structure 
can be made watertight by properly calking with a steel calking 
chisel (see Fig. 115). In fact, this is the common and very successful 
practice at present. Lead wool, introduced a few years ago, has 
been successfully used without oakum on similar work, and in special 
cases, as when used for calking joints in structural steel work where 
watertightness is an essential feature of the structure. 

It is often necessary to make floor joints of buildings watertight 
so as to prevent leakage and consequent defacement of the ceiling 
below when the floor above it is washed. A compound well adapted 
for filling such joints, and for filling knot holes in wooden floors 
and for other similar purposes, is made of five parts of fresh cheese 
(the so-called Dutch or cottage cheese), one part of unslaked or pul- 
verized lime, both by volume, kneaded together to a stiff dough. 
This mixture becomes stone-hard, and is insoluble in water. By 
the addition of mineral colors, such as raw or burnt sienna or umber, 
yellow or red ochre, Venetian or Indian red, this putty can be colored 
to any desired shade.* 

* '739 Paint Questions Answered," published by the Painter's Magazine 
of New York, 1904. 


Selection and Adaptability cf Materials. There are on the 
market numerous waterproofing materials, but comparatively few 
are extensively used. We shall examine the most important of 
them, however, to determine their general properties whence we will 
be able to better understand their use and adaptability for the 
different systems of waterproofing in which they are employed. 
The system of waterproofing and the method of application usually 
determine the character or kind of material to be used, while both 
the material and the system of waterproofing are dependent on the 
type of structure to be waterproofed. For, obviously, an existing 
structure presents different conditions and waterproofing possi- 
bilities from one in the course of construction. Again, a tunnel or 
subway presents different conditions and difficulties than does a 
building or bridge. Hence the need for different waterproofing 
systems, methods and materials. Of course, where several materials 
are equally good, or methods equally applicable, then cost governs. 
A low first cost, however, is not necessarily the most economical, and 
it behooves the architect, engineer and contractor to be calculating 
and cautious in this regard. 

Materials for Different Systems of Waterproofing. Nearly all 
waterproofing materials readily fall under the six systems of water- 
proofing previously considered, namely: (1) " surface coating"; 
(2) "membrane"; (3) " mastic"; (4) " integral"; (5) " self- 
densified concrete "; (6) " grouting process." 

Each system however, has certain materials best adapted to 
itself as, for example, in the "surface coating" system, are used: 

(a) Scores of patented and secret compounds. 

(6) Coatings of elaterite, paraffin (oil and solid), mastic, tar, 
asphalt, and mixtures of these, cement, cement grout, neat cement, 
and mixtures of caustic potash or soap and alum. 

(c) Paints composed cf suet, lime, asphalts dissolved in naphtha, 
in benzine or mixed with linseed oil, and other hydrocarbons. 

(d) Enamels consisting of mixtures of linseed oil and rosin or 




bitumen; solutions of bakelite, and proprietary bituminous com- 

In the membrane system are mainly used: 

a. Bitumens 

6. Sheetings 

c. Metals 

Natural (refined). 

Asphalt Artificial (Asphalt-petroleum residuum). 

f Coal-tar. 
Pitch* Oil-tar. 

I Proprietary. 

Asphalt saturated felts, papers and fabricsf 
Coal-tar pitch saturated felts, papers and fabrics. 
Oil-tar pitch saturated felts, papers and fabrics. 
Saturated asbestos-felts, asbestos-covered sheet metal. 

Plate steel. 

Cast steel. 

Cast iron. 

Sheet lead, sheet tin, sheet copper, sheet iron. 

In the mastic system are used : . 

(a) Coal-tar pitch sheet mastic, asphalt sheet mastic. 

(6) Brick-in-mastic courses, tile-in-mastic courses. 

In the " integral " system are used: 

(a) Scores of patented and secret compounds. 

(6) Fattening and void-filling materials, such as hydrated lime, 
colloidal clay, mixtures of iron and salammoniac, stearin and stearates, 
gelatinous and bituminous compounds, powdered calcium minerals, 
and combinations of some of these; also, graphite and petroleum oils. 

In " self-densified concrete" are used: (a) All the well-known 
mineral aggregates, as stone, gravel, sand and cement, plus experi- 
enced labor and careful supervision. 

In the " grouting process " are used: 

(a) Patented and special cements. 

(6) Portland or natural cements (either as neat cement, or with 
sand as grout, and either wet or dry) . 

All of the above materials may again be approximately grouped 
under the general terms of " chemical " and " mechanical " - act- 

* Pitch is a general term including asphalts and many other substances of a 
hydro-carbon nature, but by usage in the waterproofing field has come to be 
regarded as the designation of coal-tar products, especially coal-tar pitch. 

| Fabrics include Jute, Paper and Cotton (Burlaj)), also Cotton drill. 


ing materials depending on whether they act directly or indirectly 
as waterproofing agents, i.e., whether they act through a chemical 
or mechanical change or adaptation, either in their own structure 
or the body of the concrete. This is not always certain or easy to 
determine, but the following division is sufficiently correct for all 
practical purposes. 

(a) Materials acting chemically as waterproofing agents: 
Soap, alum, caustic potash, suet, stearin and stearates, rosin, 
calcium, minerals, linseed oil, lime, hydrated lime,* salammoniac, 
powdered iron, Portland cement, natural cement, Puzzalon cement, 
sand cement and neat cement. 

(6) Materials acting mechanically as waterproofing agents: 
Paraffin, asphalt, elaterite, gilsonite, grahamite, tar, bakelite, 
coal-tar pitch, oil-tar pitch, mastic, bituminous paints, colloidal clay, 
graphite, gasoline, benzine, naphtha; treated paper, paper burlap; 
treated asbestos felt, treated rag and pulp felt, jute burlap, fabric, 
cotton drill; cast iron x plate steel and all sheet metal, water, sand, 
gravel, stone, cement grout and cement coatings. 



A certain amount of knowledge regarding the nature of these 
materials is essential to the proper understanding of their use and 
application in the art of waterproofing. It was therefore deemed 
expedient to make the following notes relating to, and affecting 
their use in waterproofing engineering. It is not intended that these 
remarks be exhaustive, but merely explanatory of the properties 
and uses of the more important materials. 

Alum. Common alum is a white powder or crystalline substance 
consisting of a double sulphate of aluminum and potassium. It is 
found native as kalinite and manufactured. It is soluble in 
boiling water in equal parts by weight, but only about 5 per cent 
in water at 60 deg. Fahr. (15.5 deg. Cent.). In the form of a solu- 
tion it is brushed on a masonry or concrete surface over a previous 
coat of soap solution with which it combines chemically forming a 
stearate of aluminum which acts as a void-filler and also forms a 
water-repellent coating. 

Calcium (compounds). Calcium is a lustrous, white, very duc- 
tile, and malleable metal about as hard (and scarce in the pure form) 
as pure gold. It has the peculiar property of decomposing water 
* Also acts in part at least as an inert void-filler. 


with evolution of hydrogen. Calcium compounds, are salts of 
calcium and it is these that are used in waterproofing. They occur 
largely diffused in nature in the form of chalk, marble, limestone, 
coral, etc. As calcium sulphate or calcium carbonate (marble) 
it is used in powder form in the manufacture of dampproof paints. 
These compounds when mixed with cement and aluminum, form 
many secret (?) waterproof and dampproof surface-coating com- 

Casein. Casein is an albumen found in the milk of animals. 
When milk curdles it is due to the coagulation of the casein present, 
which averages about 3 per cent. Acetic acid or a bit of rennet 
will produce curdling and the casein separates as curd. Casein 
is not easily affected by heat. When moist and fat-free, it forms 
insoluble precipitates with quicklime, borax or strong sodium silicate 
solutions. In any of these forms it is used as a waterproofing cement. 

Caustic Potash. Potassium hydroxide is commonly called 
caustic potash. It is a white, solid substance, very easily melted 
and quite soluble in water or alcohol. In solution it possesses, in the 
very highest degree, the properties termed alkaline. In water- 
proofing it is sometimes substituted for soap as a surface coating, 
or it is used with various chemicals in secret (?) waterproofing 

China Wood Oil. China wood oil is obtained from the seeds 
of the fruit that grows on the wood oil tree of the Aleurites species 
of China and Japan. These trees are of comparatively rapid growth, 
with trunks of light, soft wood. The oil is a rapid drying one and 
is largely used in the manufacture of varnish and waterproof cements. 
It is often advantageously substituted for linseed oil in the manu- 
facture of some waterproof paints and varnishes. It is slightly 
heavier than the boiled or raw linseed oil, its specific gravity being 

Hydrated Lime. Hydrated lime is a finely divided white powder 
made of ordinary lime by the addition of just sufficient water to 
insure complete slaking, and so that the heat generated will evaporate 
all the excess water, leaving the product dry. There are several 
grades made, the difference being mainly in the calcium and mag- 
nesium content; but this is dependent on the source of the carbonate. 
High magnesium lime, though it slakes and sets slower, is superior 
in other important properties to the high calcium limes. For 
ordinary purposes hydrated lime is used for and in precisely the 
same way as common lime. In waterproofing it is used to a greater 
extent than common lime as it is much more effective, because when 


properly manufactured, it slakes and mixes more thoroughly in the 
concrete (see Chapter III). 

Iron (Powdered). Iron is an element abundant in nature and 
universal in its existence and application. For waterproofing pur- 
poses pig iron is used in granulated or powdered form. When mixed 
with appropriate chemicals, as, for instance, salammoniac, sulphur 
and even cement, it forms a surface-hardening substance for concrete 
and mortar. When mixed with water, it forms and is often used as 
a " rust joint." In this manner it is sometimes used in calking 
joints in cast-iron tunnel linings. It can readily be tempered in its 
oxidizing action by mixing it with Portland cement. 

Lime. Lime is a white substance resulting from the burning 
of limestone in kilns until the carbon dioxide is driven off as a gas, 
leaving the calcium oxide, or lime, which slakes when water is added 
to it. On exposure to the air it sets and hardens, by reverting to 
its original state, i.e., it takes in carbon dioxide from the atmosphere. 
It is often incorporated in concrete and mortar to reduce their 
porosity, or mixed with certain salts in cement mortar to form a 
waterproof mortar coat. But its benefits are limited as well as its 
use, because it will not set under water. 

Linseed Oil. Linseed oil is obtained from the seed of flax either 
by pressing or by extraction with naphtha or other solvents. It is 
used either raw or boiled; the boiled toughens or dries quicker in 
air. The unadulterated linseed oil possesses a characteristic but 
disagreeable taste and odor. Its color is light amber or greenish 
yellow. The boiled oil dries more rapidly on exposure to the air 
than the unboiled and is mostly used for interior work, the raw for 
exterior work. Both kinds thicken and toughen with time, and dry 
by oxidation, i.e., they have the property of absorbing oxygen and 
forming a tough and elastic substance which, however, eventually 
deteriorates. It is often used to flux asphalt and coal-tar pitch, 
to make surface coatings for dampproofing and waterproofing 

Natural Cement. Natural (or Roman) cement is a very fine 
powder, made from clinkers resulting from the burning, at a com- 
paratively low temperature, of an impure limestone, containing from 
15 to 40 per cent of silica, alumina and iron oxide. It was first 
manufactured in England in 1796 by James Parker. This cement is 
comparatively slow setting and is not as widely used as Portland 
cement. Neither is it as reliable, because the proportions vary 
not at will, but according to the nature of the source. It is not 
generally used where a very impervious concrete is desired. 


Neat Cement. Neat cement is a term applied to a paste-like 
mixture of cement and water regardless of proportions. It is 
applicable to any kind of masonry both above and below ground 
surface in the form of a thin coat or surface wash. The thicker the 
coat however, the more impermeable it is and hence the more effec- 
tive as a waterproofing agent. Neat cement is often used for grout- 
ing purposes especially where rock seams or cracks are small but 

Portland Cement. Portland cement (named for its resemblance, 
when set, to limestone quarried at Portland Isle, England, where it 
was first made in 1811, and patented by Joseph Aspdin, a bricklayer, 
of Leeds, England, in 1824), is a very fine powder made from clinkers 
resulting from the burning, at a temperature of about 3000 deg. 
Fahr. (1649 deg. Cent.), of a finely ground artificial mixture of lime, 

FIG. 60. 

A. Cement Rock, as it Appears in Nature. 

B. Cement Materials being Burned in Rotary Kilns. 

C. Cement Clinker as it Comes from the Kilns. 

D. Cement, Ground Fine for Use. 

silica, alumina and iron oxide in certain definite proportions (see 
Fig. 60). This combination is made by mixing limestone or marl 
with clay or shale in the proportions of about three to one respec- 
tively. The finer the cement the more impervious is the concrete 
made with it. Most concrete construction is done with Portland 

Puzzolan Cement. Puzzolan cement is a mechanical mixture 
of powdered slaked lime with either a volcanic ash or a blast furnace 
slag. In the form of a mixture of powdered slaked lime and volcanic 
ash, puzzolan cement was first used by the Romans in their building 
construction. Unlike the other cements, this mixture is not burned 
but is finely ground. The resulting powder is somewhat superior 


to other cements in its resistance to the action of sea water, for 
which reason it is often used in maritime construction. 

Resin. Resin is a solid or semi-solid substance composed of 
carbon, oxygen and hydrogen, mainly of dark amber color, homo- 
geneous and translucent, though some varieties are colorless and 
transparent. It is mostly of vegetable origin. Common rosin 
is a similar substance remaining when turpentine, from gum or pine 
resin, is distilled until the water and volatile oils are expelled. Resin 
is insoluble in water but soluble in alcohol, ether and various oils. 
Rosin is used extensively as a flux in inexpensive paints, varnishes, 
dampproofing and roofing compounds in which it acts as a filler 
and for making soap. Nearly all surface coating compounds con- 
tain resin or rosin, where it is often used as an adulterant and tends 
to make the compound brittle. 

Salammoniac. Salammoniac (NH4-C1) is ammonium chloride, 
a white crystalline substance, obtained from the ammoniacal waters 
of gas works by adding sulphuric acid and then sublimating the sul- 
phate thus formed with sodium chloride, or by absorbing ammonia 
gas in hydrochloric acid, also by heating ammonium sulphate with 
common salt. It is freely soluble in cold water, but much more so in 
hot water. In waterproofing it is mainly used as an oxidizing agent, 
particularly for powdered iron, with which it is often mixed for calk- 
ing joints in steel and iron-lined tunnels, and in modified form for 
hardening concrete surfaces, which tends to make these surfaces 
water tight and dustproof. 

Sand-cement. Sand- or silica-cement is a mechanical but inti- 
mate mixture of Portland cement with a pure clean sand, very finely 
ground together. In the best grade of sand-cement the proportions 
of cement to sand are 1 : 1 but as lean a mixture as 1 : 6 has been 
made. This cement, efficiently proportioned, has been and may well 
be used for making impervious concrete, providing the equally 
important matters of grading and mixing are properly attended to.* 

Soap. Soaps are metallic salts of the higher fatty acids or, more 
particularly, compounds formed by the substitution of the alkalies, 
sodium and potassium, or magnesium and aluminum for the glycerine 
in common fats. Soaps containing sodium harden on exposure to 
the air and are known as hard soaps, and those containing potassium 
absorb water under the same conditions and tend to liquefy, hence 
they are known as soft soaps. The sodium and potassium soaps 

* It is of course beyond the scope of this book to discuss in detail the respective 
properties of cements. Further and full information will be found in any stand- 
ard book on concrete. 


are water-soluble, the magnesium and aluminum soaps are water- 
insoluble. In waterproofing the -soaps are used (1) by being dis- 
solved in water and the solution brushed on a concrete or other 
masonry surface and then coated with an alum solution with which 
it unites chemically forming an insoluble stearate (soap) of aluminum 
which acts as a void filler and water repellent; (2) by being suitably 
mixed with colloidal matter it is often incorporated in concrete to 
aid in increasing its density. Castile soap is most generally used in 
making soap solutions, but any of the common soaps in everyday 
use may also be used. Aluminum soaps are used for making various 
proprietary integral waterproofing compositions. 

Stearate. Stearate is a salt of stearic acid. Stearates, such as, 
for example, ammonium stearate or lime stearate, are used as integral 
waterproofing compounds. They have the consistency of hard 
soap and are mostly insoluble in water but are decomposed by most 
acids. Ammonium stearate can be made by taking stearic acid and 
combining it with ammonium hydroxide in the presence of con- 
siderable water or water-yielding material. This forms a more 
or less air-unstable quasi-soap of a water-soluble nature. This 
soap-like material, when brought in contact with cement in 
the presence of moisture, reacts and forms a water-insoluble 
stearate, with, water shedding properties, while the alkali, that is, 
the ammonia, being liberated as a volatile, supposedly disappears 
in time. 

Stearic Acid. Stearic acid is a derivative product of the more 
solid fats of the animal kingdom and vegetable fats, especially those 
of cacao-beans, and certain African nuts. It is prepared from mutton 
suet or cacao fat by saponifying* the fat with soda-lye. Pure stearic 
acid has a specific gravity of 1.00 at 50 deg. Fahr. (10 deg. Cent.). 
It melts at 156 deg. Fahr. (69 deg. Cent.) to a colorless oil, which 
cools into a solid, white scaly mass. It is insoluble in water and is 
much used for making dampproofing varnishes and integral water- 
proofing compounds. 

Stearin. Stearin, a solid substance at ordinary temperatures, 
is the chief ingredient of suet and tallow. Stearic acid is obtained from 
it by the application of steam to the harder fats, and chemical 
treatment. Stearin is used for making various waterproofing 
materials, and is often mixed with asphalt to make proprietary joint- 
filling compounds. 

* Saponification is the process by which the fatty acids and glycerine are 
separated with the latter set free; that is, the process of converting a fat or oil 
into a soap by combination with an alkali. 


Stearin Pitch. Stearin pitch is an animal by-product obtained 
from stearic acid in the manufacture of candles. It is used as a 
coating for some smooth-surfaced ready roofings, and is a very 
stable material, being practically unaffected by the action of the sun. 

Suet. Suet is animal fat, especially the harder and less fusible 
fat about the kidneys and loins, and whose chief ingredient is stearin. 
It is cheap and when chemically treated is used as a water-repellent 
for mass concrete. When mixed with colophony in certain propor- 
tions it is used as a dampproofing and as a water-repellent varnish. 



Asbestos. Asbestos is a fibrous mineral (see Fig. 61, A, B) 
derived from certain igneous and metamorphic rocks (by the action 

FIG. 61. 

A. Asbestos as it Comes from the Mines. 

B. Asbestos Fiber as Used with Bitumen to Form Plastic Compounds. 

of heated waters, in nature) and is chemically known as a hydrous- 
magnesium silicate. Commercially asbestos has been used since 
ancient times, but its discovery is attributed to the Romans. It is 
incombustible and non-perishable and because of its fibrous nature 
is often incorporated in- various bitumens to form a plastic water- 
proofing cement. It is also powdered, and in this form it is used as 
a filler in dampproofing paints. It is also used for making asbestos 
felt which is often saturated in the same manner as roofing felt 
and also used for the same purpose. As such it is, however, much 
more expensive. It is also made into roof shingles. 

Asbestos Felt. Asbestos felt is made of about 95 pier cent asbestos 
with some form of sizing to permit its being rolled into long thin 
sheets of various widths and thicknesses similar to roofing felt. It 


is weaker than the ordinary felts, does not saturate as well, and has 
not as wide an application, but it will not decay and is fireproof 
while the felts and fabrics are not. This latter property is inherent 
in the asbestos proper. Asbestos felt, saturated with bitumen, is 
mostly used for roofing, and is ordinarily applied only by the manu- 
facturer. Sheet iron covered on both sides with asbestos felt is 
used as a form of fireproof and waterproof roofing. 

Asphalt. Asphalt is a solid or semi-solid native* bitumen found 
in a natural state, or produced artificially, as petroleum residuums. 
In its origin it is decomposed vegetable matter comprising mainly 
carbon and hydrogen of complex Ynolecular construction, but also 
containing oxygen, sulphur and nitrogen in very small proportions. 
As found naturally, asphalt is not commercially available even 
after the impurities are removed, being usually too hard and 
brittle for waterproofing purposes. This is ordinarily remedied by 
softening or fluxing with various petroleum oils, which fluxes have an 
important effect upon the finished product. The fluxes should be 
sufficiently stable to insure against too rapid hardening of the fluxed 
asphalt. To avoid the process of fluxing, which requires skill, a 
straight refined asphalt from petroleum oil of an asphaltic base is 
used. Pure bitumen has a density less than water, but in con- 
sequence of impurities mixed with it, its specific gravity varies from 
1.0 to 1.7. The distinguishing characteristics of all bituminous 
substances are their elasticity and binding power (or adhesiveness), 
their considerable immunity against attack by water and their solu- 
bility in oils and certain other organic compounds. Most water- 
proofing asphalts are elastic at ordinary temperatures, slightly 
viscid at low temperatures and usually liquid at comparatively high 
temperatures. Asphalt is quite soluble in petrolic ether, and entirely 
soluble in carbon bisulphide. Aside from the paving industry where 
nearly all varieties of asphalt are used and the varnish industry 
where the very best and purest varieties are used, it is chiefly used as a 
saturant, coating and bonding material for felts and fabrics in the 
membrane system of waterproofing, and as binding material in the 
mastic system of waterproofing. 

Bakelite. Bakelite is an artificial coal-tar product produced by 
warming together equal weights of phenol and formaldehyde and a 
small amount of an alkaline agent. The resulting mixture separates 
into two layers, the lower of which, when heated above 212 deg. 

* The term " native bitumen " implies that the natural asphalt, such as 
Bermudez or Trinidad asphalt, requires treatment merely for the removal of 
water and extraneous organic and inorganic materials before using. 


Fahr. (100 deg. Cent.) and worked under a pressure of 50 to 100 
pounds per square inch, results in a hard, solid, inelastic mass 
known as bakelite, from its inventor, Dr. Leo Baekeland. This 
mass has a specific gravity of 1.25 and is an excellent insulator, 
but when dissolved in neutral petroleum oil is used as a varnish for 
dampproofing and waterproofing purposes. 

Benzine. Benzine is a light volatile petroleum oil used as a 
solvent for fats, gums, resin and bitumen. Bituminous solutions 
are formed with this petroleum oil and used as a surface coating 
which penetrates into the pores of the concrete to which it is usually 
applied with a brush. After evaporation the bitumen remains 
in the pores and on the surface in the form of a thin coat. 

Benzol. Benzol (or benzene), CeHe, is a volatile, colorless, fluid 
hydrocarbon, obtained as a by-product from the distillation of coal- 
tar and water-gas tar, and from petroleum. It was discovered 
first by Faraday, in 1825, in oil gas, and by Hofmann, in 1845, in 
coal-tar. Benzol is an active solvent for fats, resins, most bitumens 
and is used for that purpose in waterproofing. 

Bituminous Paints. Some bituminous paints are made of solu- 
tions of liquid paraffin in either asphalt or coal-tar pitch, or by mixing 
bitumen, while hot, with some drying oil such as linseed oil, or China 
wood oil with either of which the bitumen readily enters into solution. 
Similar products are obtained by mixing paraffin and petroleum with 
naphtha, benzine or gasoline. Some of these paints are applied hot, 
others cold. Some will adhere to a wet surface or a surface under 
water, but most of them need a thoroughly dry surface. They are 
in general quite durable, cheap and easily applied. 

Burlap. Burlap is made of jute, which is the fiber obtained from 
the inner bark of the Asiatic plant, genus Corchorus, of the Linden 
family. It is a very cheap fiber, woody in its nature and more 
perishable than flax. It is mainly grown in the northeast section 
of India, and is manufactured in Calcutta, but the best grades of 
burlap are manufactured in Dundee, where the industry was first 
started on a commercial scale in 1838. The burlap is woven in many 
widths and has considerable tensile strength. It is sold by weight. 
The most used varieties for waterproofing purposes are 7, 7|, and 8 
ounces per square yard. This weight, however, is materially affected 
by the moisture content, which under normal conditions, that is, 
at an average relative humidity of 70 per cent, the jute may con- 
tain about 14 per cent of moisture by weight. Burlaps of these 
weights have open meshes, the size of which vary with the weight, 
as, for example, the 7-ounce burlap is approximately 60 per cent 


open, the mesh being about i inch square. The size of the mesh 
decreases with increase of weight. Burlap in the raw state is some- 
times used as reinforcement, in the membrane system of water- 
proofing; but when saturated and coated with asphalt or oil-tar 
pitch, which preserves it, it is very extensively used in membrane 

Cast Iron. The cast iron here considered is that usually used in 
the construction of tunnels and for tunnel linings. The best castings 
for this purpose are made of gray iron produced by the cupola proc- 
ess, of the second melting. The castings, called tunnel segments, 
must be true to pattern and flawless in every other respect. In 
order to reduce the leakage through the joints to a minimum the 
castings are faced by machine. Provision must also be made for 
calking the flanges after the segments are erected (see Fig. 136) . 

Cement Mortar (Grout). Cement mortar or grout is a mixture 
of cement, sand and water in any proportion from 1:1 to 1:6. 
This mixture is termed mortar or grout when the size of sand does 
not exceed that Which will pass 100 per cent through a 4-mesh sieve, 
or what is ordinarily called " bird-sand." When it does exceed the 
J-iflch size, a smaller aggregate is required to fill the voids besides 
the cement, and this mixture is therefore correctly termed con- 
crete. Cement grout of the proportion 1 : 1 or 1 : 2 is used very 
successfully in the grouting process and as mortar in the surface- 
coating system of waterproofing. In the above proportions it is very 
impervious, but as a coating its impermeability also depends on its 
thickness. It adheres readily to a roughened surface and is applica- 
ble to any kind of masonry. 

Clay. Clay is an uncrystallizable silicate of aluminum. It is 
produced in nature by the disintegration of the various silicates of 
aluminum in the stones known as feldspars and micas, due to weath- 
ering. Clays are usually moist or wet and plastic in varying 
degrees depending in part on the fineness of the grain and in part 
on the amount of colloidal substances present. This plasticity may 
be increased by the addition of water. The fineness and glue-like 
or gelatinous composition of clay makes it a good inert void filler, 
and in small quantities is used for that purpose in mineral paint and 
mass concrete. It is often used as a cutoff in specially constructed 
expansion joints in masonry structures. In the form of a thick 
blanket (not less than 4 inches thick) applied to an underground 
structure, for instance, it can be made a very efficient waterproofing 
medium for equal mixture of clay and Portland cement is used for 
a like purpose. 


Coal-tar Pitch. Coal-tar pitch is a semi-solid or solid residue 
resulting from the fractional distillation or boiling of coal-tar. This 
process removes certain volatile oils and results in a black, more or 
less viscid residuum product called coal-tar pitch. There are various 
grades of pitch, the best being used for general waterproofing. In 
comparison with asphalt, this best grade of coal-tar pitch is harder 
at low temperatures and more liquid at high temperatures than 
the asphalt. It is, however, more adhesive at ordinary temperatures 
and less affected by water than most asphalts; but it is somewhat 
less durable in air.* Coal-tar pitch contains free carbon, in amounts 
depending on the method and degree of reduction, and the source 
of the tar. The more free carbon in pitch up to about 30 per cent 
the less it is affected by changes in temperature and apparently has 
more " life " than another with less free carbon, f Coal-tar pitch is 
extensively used as a saturant, coating and bonding material for 
waterproofing and roofing felts and fabrics and is in close competition 
with asphalt for use as binder in the membrane system of water- 

Cotton Drill. Cotton drill, as usually used in the membrane 
system of waterproofing, is a woven-cotton fabric, weighing not less 
than 4 ounces to the square yard. This weight of cotton fabric 
has a thread count of 56 by 60 per square inch. Different grades 
are made, but those generally used vary in thread count between 
34 by 34 and 66 by 68, per square inch, both inclusive. When either 
saturated, or saturated and coated with bitumen, these cotton 
fabrics are sold as standard products, but often also under various 
trade-names. The cheaper grades are somewhat less durable, and 
the better grades are usually more expensive per yard than most 
waterproofing felts or jute fabrics. Treated cotton fabric, in com- 
parison with the untreated, gains about 20 per cent in strength 
due to treatment. It is comparatively close-woven, and therefore, 
unlike the open-mesh jute fabric which acts only as a reinforcment 
in the bituminous membrane, it acts also as a waterproofing agent 
in approximately the same manner that waterproofing felts do, that 
is, it helps to keep the water out. 

Elaterite. Elaterite is a soft, elastic variety of asphalt (hydro- 
carbon), resembling India rubber, mined in Utah and Colorado, 
U. S. A., and in several places in England, notably in Derbyshire. 
It is subtranslucent, has a brownish color, and a specific gravity 
varying from 0.9 to 1.0. It is also known as " mineral rubber." 

* American Society for Testing Materials, June 24, 1913. 
| American Railway Engineers' Association, Vol. 14, p. 844, 


Commercially it is combined with certain petroleum oils, linseed 
oil, asphalt, gilsonite, and even castor oil (because the latter is a 
non-drying oil), and used as a surface coat on concrete. The com- 
pounds thus formed are quite plastic at all temperatures to which 
this climate is subject to. Elaterite is very difficult to melt, but in 
solution with various materials forms a much used dampproofing 

Felt (Waterproofing) . Felt made for waterproofing purposes is a 
product composed chiefly of pulp or cotton rags with a little wool; 
the latter makes the felt open and spongy, and materially increases 
its saturating power. The first mechanical process for making felt 
was invented by J. R. Williams, an American, about 1820. It is 
made in sheet form, usually 36 inches wide, and saturated with asphalt 
or tar. The asphalt felting has an advantage over ordinary coal-tar 
felting, in that it does not become brittle under the influence of heat 
or with age. As now made waterproofing felt comes in several 
thicknesses and is sold by weight or roll, the standard for the latter 
being a roll containing 3 or 4 squares, plus 8 to 12 square feet per 
square extra for laps. The quality of the raw felt is designated by 
a number as, for instance, No. 23 felt would mean a felt equal in 
weight to a ream of 480 sheets each one foot square. A No. 28 felt 
would be one weighing 28 pounds per ream.' These numbers also 
happen to approximate the weight of the felt in grams per square 
foot, which fact it may be useful to remember. There are soft and 
hard felts made, hence the word soft or hard must follow each number. 
The soft felts are usually asphalt treated, the hard ones, tar treated. 
The soft felts are usually dearer, because they contain more wool. 
All-wool felt is generally not made because of its high cost, softness 
and tenderness. A wool content of about 25 per cent produces a 
felt of good saturating power, and saturation is very essential for 
the preservation of all the raw felts. Good saturated felts are quite 
durable, but they lack tensile strength, though they gain about 500 
per cent strength due to such treatment. They readily absorb water 
though, in spite of their saturation. 

Gasoline. Gasoline is one of the very volatile distillates of petro- 
leum. It consists of a mixture of several hydrocarbons containing 
carbon and hydrogen in varying percentages. Its chief use is for 
fuel, but in waterproofing it serves as the distillate or " carrier " 
for many bitumens which readily dissolve therein. These solutions 
are applied cold to the surface of masonry, but mainly for damp- 
proofing purposes. The gasoline penetrates the pores of the masonry 
surface, carrying with it the bitumen which remains after evapora- 


tion. Thus, besides forming a film on the surface the pores are also 

Gilscnite. Gilsonite is a hard and brittle, native bitumen, mainly 
found in Colorado and Utah, with a specific gravity of 1.07. It is 
lustrous black and equally soluble in cold carbon tetrachloride and 
carbon bisulphide. It is also readily soluble in heavy asphaltic 
petroleum. When mixed or fluxed, while hot, with certain petroleum 
residuums (it begins to melt at about 480 deg. Fahr. 249 deg. Cent.) 
in proportions according to the consistency desired, a rubbery and 
somewhat elastic but only slightly ductile material is formed. Gil- 
soriite is mainly used for making dampproof paints and varnishes 
and proprietary waterproof compounds mostly for surface coatings. 
It is sometimes mixed with a light asphaltic residue to bring the 
latter's consistency up to certain specification requirements for par- 
ticular waterproofing purposes. 

Grahamite. Grahamite or " Choctaw " is a hard and brittle 
native bitumen mainly from Oklahoma, with a specific gravity of 
1.14. The deposit is now exhausted. It is a dull black and melts 
only with great difficulty (at about 500 deg. Fahr. 260 deg. Cent.) 
and therefore has but a limited use. It is slightly soluble in alcohol 
and partly so in ether, petroleum, and benzol, but almost completely 
in turpentine and entirely in carbon bisulphide and chloroform. It 
is used for the same purposes as gilsonite. 

Graphite. Graphite is essentially a pure carbon which comes in 
two forms flake and amorphous and found abundantly in nature. 
It is friable and has an oily quality, for which reason it acts as a 
lubricant. (Lamp-black or soot should not be substituted for 
graphite because they have not the same properties.) Graphite 
when finely ground and mixed with silica and linseed oil is commonly 
used as a preservative paint for metals. For waterproofing it has a 
limited use as an integral because of the black color it gives to the 
concrete. Hydrated lime serves the same purpose, i.e., as a lubricant 
for the concrete aggregate, without this defect. Graphite enters 
into many dampproofing compounds. 

Gravel. Gravel is an aggregation of water-worn and rounded 
fragments of rocks, in which quartz is the most common mineral. 
Included under the name gravel are pebbles ranging in size from 
J inch to 2 inches. Gravel is usually classified according to the 
largest size pebble which it contains as, for instance, IJ-inch gravel; 
1-inch gravel; f-inch gravel, etc. For making impervious concrete, 
gravel must be sound and clean. Concrete is considerably densified 
by using gravel graded from fine to coarse, but the best results follow 



when it contains no pebbles that will pass through a hole f inch in 
diameter and none that will not pass through a hole l\ inches in 
diameter. No gravel that is all of one size or practically so should 
be used where impervious concrete is desired. 

Jute Fabric. Jute fabric* employed in the art of waterproofing 
is a burlap saturated and coated with asphalt or coal-tar pitch. 
When thoroughly saturated and coated it is very much less perishable 
than raw burlap, while its strength is nearly doubled thereby. It 

m Hint unit utisti 

!*& *tl*f|, 

1 ' 

||*t**i ***ll 

*!. 4 iifti**i 

tlfiPUWMlf *!*!. 

FIG. 62. 

^4. Seven-ounce Untreated Burlap, Showing open Mesh. 
B. Same Burlap, Saturated and Coated with Asphalt. 

retains between 35 and 50 per cent of its open mesh after treatment, 
becomes more pliable, and weighs between 14 and 18 pounds per 100 
square feet. It acts as a reinforcement in the waterproofing mem- 
brane much the same as does expanded metal in reinforced concrete 
slabs. It is now very extensively used for waterproofing under- 
ground structures, and is in keen competition with felt, which, 
formerly, was used exclusively. Fig. 62, A, shows a photographic 
reproduction of a piece of 7-ounce raw burlap; Fig. 62, B, shows 
the same piece properly saturated and coated with bitumen. 

* "Manufacture, Test and Use of Waterproofing Fabric," Engineering News, 
September 24, 1914. 


Mastic. Mastic employed in the art of waterproofing, is composed 
of asphalt or coal-tar pitch mixed with cement or limestone dust 
often also with sand, and all in varying proportions depending 
on the particular use to which it is put. Mastic may also be made 
of fluxed natural rock asphalt and grit. The mineral matter in the 
mastic gives it " body " i.e., makes it more substantial, raises its 
melting-point, lessens the fluidity and increases its bearing power 
as compared with the bitumen used. The latter properties depend 
on the relative proportion of the bitumen and mineral matter. The 
usual proportions for waterproofing-mastic such as used with bricks 
to form a brick-in-mast'ic layer are from 30 to 50 per cent of bitumen, 
the remainder being equal proportions of sand and cement. The 
sand used in making the mastic is usually fine enough to pass 100 
per cent through a 10-mesh sieve. In some cases, the mastic is 
used as mortar with bricks for waterproofing floors, walls, roofs and 
underground structures. It is often used alone to form a continu- 
ous sheet an inch or more in thickness, to waterproof subsurface 
structures. For such use the mastic may contain from 10 to 15 
per cent of bitumen, 8 per cent cement, 40 to 45 per cent 
limestone dust, 25 per cent grit and from 12 to 17 per cent 
of sand. 

Naphtha. Naphtha is a thin white oil obtained mainly from 
petroleum by distillation and also from the distillation of wood and 
coal-tar. There are several varieties and grades of naphtha and 
they are differentiated by their boiling-points and specific gravity 
but all are hydrocarbons. Commercial bitumen is partly soluble 
in naphtha but when heated in a steam-jacketed kettle and not 
thinned out too much, a mixture of the two is obtained in which the 
part of the asphalt not dissolved is held in suspension. In this form 
it is used for making bituminous dampproofing paints. 

Oil-tar Pitch. Oil-tar pitch is the residue of the distillation of 
oil tar, which itself is a by-product of the manufacture of oil gas 
or carbureted water gas. It is produced in the cracking of oil vapors 
at very high temperatures. This process causes the oils to undergo 
marked changes and to acquire some of the characteristics found 
in coal tar. These oils are then distilled down and treated much as is 
coal tar, resulting in what is known as oil-tar pitch. The free carbon 
content of oil-tar pitch is low, ranging between 5 and 15 per cent; it 
is, however, always less viscid than coal-tar pitch, though about equal 
in its resistance to the action of water and not materially less stable 
than coal-tar pitch. Its chief use is on roofs of buildings as a roof- 
ing binder and sometimes as a saturant for waterproofing felts and 


fabrics. Where -coal-tar pitch is to be applied as a surface coat, 
oil-tar pitch is often used as a primer because of its penetrating 
power, but for this purpose dead oil is preferable. 

Paper. Paper was first made by the Chinese, from whom it spread 
to other races, and was brought to Europe in the Twelfth Century. 
The first paper mill in America was built by William Rittenhouse, 
at Roxborough, near Philadelphia, in 1690. There are innumerable 
varieties of building paper on the market, but in waterproofing 
only two or three of these are used. These are made of various 
kinds of wood pulp, rope, rags or wool or from a combination of pulp 
and rags or wool. None of these papers can be completely saturated 
with bitumen, but all can be sufficiently saturated to preserve them 
for a considerable time. Those known as " building papers " are 
not saturated at all. Some papers are merely coated on one or both 
surfaces with bitumen. Some are weak in tension, others very 
strong, and of late a very strong variety of paper has been success- 
fully treated and is sometimes used in place of felt. 

Paper Burlap. Paper burlap, as made for waterproofing pur- 
poses, is an open mesh paper fabric, similar to jute burlap and some- 
times substituted for it. It can be saturated with bitumen only 
with difficulty. It may be used in waterproofing in the same manner 
as jute burlap. It comes in several weights and widths and is 
slightly reinforced with cotton, but it is not nearly so strong as the 
jute variety. It is also more perishable. By pasting a very thin 
tissue paper completely over one side of the paper burlap and coat- 
ing the whole with a tacky asphalt or coal-tar product, it is made 
into an efficient electric cable duct wrap. 

Paraffin (Solid). Solid paraffin is a hard, white, waxlike sub- 
stance, chemically of the higher hydrocarbons. It is obtained by 
distillation from petroleum,* but is also found native in coal and 
other bituminous strata. The manufacture of paraffin was begun 
in 1851 by James Young, a Scottish chemist. It is very inert, insoluble 
in water, and can be mixed in all proportions in various oils when 
in a melted condition but lacks adhesiveness and is useless as a 
binding material. For waterproofing it is often mixed with asphalt 
(complete solution therein is essential) , or used alone in various ways, 
e.g., to render fabrics waterproof. When used unblended, as a 
masonry surface coating it is the most efficient waterproofing medium 
for the purpose. It is also used in the manufacture of secret (?) 
waterproofing compounds. 

* The Pennsylvania and, in general, the Eastern (U. S. A ) oils are largely 
made up of compounds of the paraff n scries. 



Paraffin Oil. Paraffin oil is a by-product of the manufacture of 
paraffin. It is a liquid compound practically of the same nature as 
the solid paraffin with the same properties and adaptability as 
regards waterproofing. Both kinds of paraffin are extensively 
used as surface coatings for stone, brick, and concrete, making the 
latter both dampproof and waterproof. Stones are often impreg- 
nated with paraffin to prevent erosion when exposed to the elements. 

Sand. Nearly all sand is more or less pure quartz grains which 
will all pass through a J-inch sieve with not more than 8 per cent 
passing a No. 100 sieve. The sand best suited for making impervious 
concrete is coarse, sharp and silicious, containing not more than 2 
per cent of mica, loam, dirt or clay, separately or combined. For 
good results as regards impermeability it should be graded about as 
follows : 

No. of Sieve. 

Limit of 
(Per Cent 
Passing) . 

Limit of 
(Per Cent 
Passing) . 


















See Appendix 1 for explanation of mechanical analysis curves 
for grading concrete aggregates. 

Steel Plate. Steel plate used for tunnel linings is made by the 
open-hearth process.* In tunnel construction, it often acts both as a 
structural component of the tunnel and its waterproof lining. To 
reduce leakage through the joints to a minimum after erection, the 
plates should be perfectly fitted and riveted through properly 
reamed holes. Edges of all plates must be planed and calked inside 
and out. When steel plates are used for tanks and sometimes even 
for structural purposes it is also necessary to make the joints water- 
tight. A very good scheme is to introduce a strip of treated felt 
a little wider than the pitch of rivets between the joints. The heat 
and compression of the rivets bring out the cementing properties 
of the joint filler. 

Stone Aggregate. Stone used for concrete consists mainly of 
trap, limestone, marble, granite, syenite and gneiss. The composi- 

* The Journal of the Municipal Engineers of the City of New York, Vol. 1, 
No. 6, p. 16 ; December 1, 1915. 


tion and characteristics of these stones are more or less a matter of 
common knowledge, and a discussion of their properties would 
encumber this article. What is true of gravel, as regards the making 
of dense concrete, is approximately true of any of these stones for 
the same use. See Appendix 1 for explanation of mechanical analysis 
curves for grading concrete aggregates. 

Tar. (A) Coal tar: Coal tar is a black, more or less viscid, 
oily liquid, a mixture of hydrocarbon distillates resulting from the 
destructive distillation of soft coal in the production of illuminating 
gas. It was first recovered in 1771 by Stauf, a German chemist. 
There are various kinds of tars, depending on the type of oven and 
kind of coal used. The chief difference in these tars is the varying 
percentage of free carbon present. By fractional distillation, that is, 
by the removal of certain of the more volatile oils present in the crude 
tar, it can be carried to a point at which the residuum in the still 
has acquired any desired consistency at normal temperature. This 
semi-solid or solid residual product is called pitch. The best water- 
proofing pitches are obtained from straight-run (unadulterated) 
coal tar produced at reasonably high temperatures, though for 
roofing purposes pitch is also made of oil and 'water-gas tars. Coal 
tar is used as a dampproof and protective paint and for saturating 
waterproofing felts. 

(B) Water-gas tar: Water-gas tar is a mixture of hydrocarbon 
distillates, produced by cracking oil vapors at high temperatures 
in the manufacture of carbureted water gas. Crude water-gas tar 
is a thin, oily liquid having a specific gravity lying usually between 
1 and 1.10. As a rule it contains a considerable quantity of water, 
which is, however, largely removed by mechanical devices before 
the tar is placed upon the market. The composition of water-gas 
tar varies with the character of the oil which is carbureted and 
varying conditions affecting the process. It always shows a low 
percentage of free carbon, usually less than 2 per cent, and is more 
easily decomposed and more affected by water than coal tar. In 
crude form it is used as a road dust-palliative. When reduced to the 
proper consistency by distillation it is used as a road binder, in the 
manufacture of a few minor waterproofing materials and for treating 
a special grade of waterproofing felt and fabric. 

Water. The term " water " is ordinarily understood to mean the 
liquid composed of two parts of hydrogen and one part of oxygen, 
chemically combined. But to the engineer the " EkO " of the water 
is of less concern than the suspended and dissolved matter in the water 
in general use. Its abundance is too often taken as proof positive 


of its purity. But reasonably pure, clean, fresh water is not always 
available. Still these qualities and the amount used in making a 
specific mixture of concrete are as essential in the making of good 
concrete as good cement, sand and stone. Water for good concrete 
should be free of every form of pollution, excessive amounts of acids 
and alkalies and all forms of organic matter. Salt water should 
never be used in making reinforced concrete. The presence of any 
of these foreign ingredients affects the cement more or less and 
reduces the density and consequently the impermeability of the 
concrete. The functions of water in concrete are: (a) to form, with 
the cement, the binding material uniting the sand and stone; this is 
accomplished automatically by dissolving the cement, forming acids 
from anhydrides, and bringing these new acids and dissolved bases of 
cement into intimate contact for chemical reaction; (b) to flux the 
cementing substances over the surfaces of the aggregate so as to 
insure extensive adhesion; (c) to act as a lubricant for the aggregate. 
These are completely operative only if the water is reasonably pure. 

Some of the materials above considered are, of course, used for 
many other purposes than waterproofing, but such enumeration 
would be foreign to this subject. 

The many secret compounds referred to throughout the book 
consist mostly of (a) chemical salts and limes; (b) solutions of 
various petroleums and linseed oil, and (c) mixtures of powdered 
metal, slag and Portland cement. 

Analyses of many patented waterproofing materials by Govern- 
ment and private chemists prove some of them of questionable merit, 
and some of but temporary value, imparting impermeability to 
concrete but for a short time only, and with some of these compounds 
unfortunately, their secrecy more often overbalances their efficacy. 


Applicability of Tools and Machinery for Waterproofing. The 
tools, implements and machinery employed in the waterproofing 
industry are somewhat connected with the asphalt pavement in- 
dustry with which most engineers and contractors are more or less 
familiar. Some tools are used in common and some implements 
are easily modified to suit either industry. The tools and implements 
are usually of simple construction, and some are often home-made, 

Saturath f Tank 

Brush to Remove 
ricess Bawdust 

FIG. 63. Diagrammatic View Showing Process of Saturating and Coating 
Burlap or Cotton Fabric with Bitumen. 

though all are supplied by manufacturers who make a specialty of 
this trade; but the machinery, such as is used for saturating and 
treating waterproofing felts and fabrics, is more complicated (see 
Fig. 63), and requires design. The manipulation of most of these 
tools and machines, however, is simple and does not require partic- 
ularly skilled labor, either in the field or factory. There are varia- 
tions and even distinctly different forms of these articles in the 
market, but those described herein are mostly standard or fast 
becoming so. 


Spherical Mastic-mixing Kettle. The mastic-mixing kettle 
shown in Fig. 64 is very extensively used by general waterproofers. 
The pot in the figure fits into the jacket, or mantle. The kettle 
and mantle are made of steel plate, with top and bottom bands. 



- FIG. 64. Asphalt or Mastic Heating Kettle. 


FIG. 65. Typical Dipper and Pouring Pail Used in Waterproofing with Asphalt 

or Tar. 


The bottom of the kettle is riveted but easily removable when burnt 
and removal is necessary. The dimensions of the kettle are as 
follows: Kettle, 38 inches diameter at top, j^-inch plate, 21 inches 
deep; bottom, f inch thick. Mantle, 40 inches diameter, 36 inches 
high, of 3^-inch plate. Kettles of 50 gallons capacity are the most 
generally used. Through the opening in the mantle a wood fire 
is built under the kettle in which the bitumen gradually melts. 
While in a hot and molten condition, the bitumen is poured into 
small kettles or pouring pails by means of dippers, both of which 
are shown in Fig. 65. 

Cylindrical Mastic-mixing Kettle. Cylindrical mastic-mixing 
kettles are well adapted for making mastic because every part of 

FIG. 66. Cylindrical Mastic Kettle. 

its interior surface is accessible to the kettleman. This is all the 
more so because straight-edged stirrers are the most generally used, 
regardless of the type of kettle. This type of kettle is made in several 
sizes, of f-inch metal, with sand and gravel-drying pockets on either 
side and a fire space underneath the cylinder, as shown in Fig. 66. 
The kettle rests directly on the ground and can readily be carried 
away by four men. 

Mechanical Mastic Mixer.* The mechanical mixer shown in 
Fig. 67 is constructed so that it can be drawn without any difficulty 
to any location or to any part of the work. It consists of a steel 
rotary drum which revolves in a fire brick-lined steel casing set on a 

* Originated by the Guelich Paving Process Co. of Philadelphia, Pa., and 
patented November, 1911. 


rectangular I-beam truck; the drum proper is 5 feet long and 34 
inches in diameter. The drum heads revolve about a horizontal 
axis, while the barrel of the drum has a 6-inch eccentricity on each 

FIG. 67. Mechanical Mastic Mixer, Rear View. (Patented in U. S. A., 

November, 1911.) 

end. The drum is perfectly smooth, being butt jointed. Within 
the drum is a series of flat, rectangular paddles set at an angle of 
45 degrees with the axis. Attached to the forward end of the drum 


is a curved rack which meshes with a gear driven by a direct-connected 
gasoline engine also at this end. To the engine is connected an air 
blower which supplies the air for vaporizing the fuel oil, the heat 
source for this machine. A fire box is connected to, but underneath, 
the truck and is also lined with fire brick. The flame spreads on 
either side of the drum and comes in direct contact with it. For 
this reason the torch is never lighted except when the drum is 

In the center of the forward head of the drum is a 10-inch hole 
through which, by the aid of a hopper the machine is charged while 
revolving. The rear end of the drum is used for discharging; an 
opening near the edge of the drum head, provided with a hinged door, 
8 by 12 inches, being used for this purpose. In this hinged door is 
a small shuttle door through which the material in the drum is 
sampled while being cooked. 

In starting the machine the mastic constituents, that is, the 
sand, grit, limestone dust and cement, are thrown into the drum 
through the hopper and at the same time pieces of asphalt are also 
thrown in so as to mix more thoroughly with the aggregate. All 
materials must be weighed, but none of them needs preheating 
preparatory to mixing. 

The total weight of the machine, when empty, is about 3 tons. 
Its dimensions are: height, about 5 feet; width, 4 feet; and length, 
8 feet. 

The capacity of the machine is about 1000 pounds of mastic in 
about thirty-five minutes. It requires one engine runner and two 
laborers to tend this machine, and between 1000 and 1400 square 
feet of 1-inch floor mastic or sheet mastic for waterproofing purposes 
can be produced by it per working day. 

The drum must be cleaned after each day's work. This is accom- 
plished by throwing some grit into it, allowing it to revolve for a 
few minutes while the torch is burning, and drawing off the product 
gradually until the drum is empty. 


Steam- jacketed Heating and Mixing Kettle. Steam-jacketed 
kettles for heating bituminous materials, or mixing bituminous 
mastic, are used in many asphalt plants throughout the country; 
but these are invariably of very large sizes, ranging between 200 
and 500 gallons capacity, and also of various forms. 

Small kettles of this type, say between 50 and 100 gallons capa- 


city, could be employed on engineering work where large quantities 
of these materials are used for floor paving or waterproofing purposes. 
While this has never been tried, so far as the author is aware, never- 
theless he feels confident that it would result in marked economy 
were these kettles substituted, where possible for the fire-heated 
kettles of the present day. This would follow for several reasons. 
It is a demonstrated fact that coal-tar pitch is robbed of some of its 
volatile oils by being heated over a fire preparatory to its use, because 
of the concentration of heat and the natural lightness of some of the 
constituent oils. Asphalt likewise suffers deterioration, though not as 
readily as pitch. The cost of handling fire-wood, plus the cost of at 

Inner Kettle 

FIG. 68. Double-jacketed, Steam-heated Mastic Mixing and Asphalt Heating 


A. Kettle with mastic mixing device. 

B. Pip? connection for kettle. 

C. Asphalt heating kettle, showing arrangement of jackets 

least three hours' overtime every day for a man to start the fires under 
the kettles at early dawn; the lack of a uniform product so often the 
result of making hand-mixed mastic; the fact that all work of any 
magnitude at all, has a steam plant working practically all the time 
with considerable waste of steam for lack of use ; all these facts taken 
together and the frequent need for replacing the burnt fire-heated 
kettles make a cost item to be considered in comparison, and would 
show it to be decidedly advantageous and economical to use the steam- 
jacketed kettles. 

Various types of steam-jacketed kettles are on the market and 
used for various purposes such as making chemicals, paper, glues, 
etc. The type suitable for heating bitumen is shown in Fig. 68, C. 
This is made of plain iron with or without a cover and with or without 



an outlet from the inner kettle. The cost of this kettle depends on 
\he capacity: 45 gallons costing about $66.00; 65 gallons $81.00; 
100 gallons about $121.00. Fig. 68, A, shows the kettle adapted to 
making mastic mechanically by the addition of a double mixer, gear, 
shaft and hand crank hinged arbor. The cost of this type of mixer 
also depends on the capacity, namely, 45 gallons about $125.00; 
65 gallons about $150.00 and 1000 gallons about $207.00. At B is 
shown the pipe connections for each style of kettle. 

The steam pressure required for raising the cold materials in these 
kettles to their proper temperature is about 100 pounds per square 
inch applied for about one hour. 

FIG. 69. Roofer's Kettle, Used for Heating Bitumen and Mastic. 
A. Mantle. B. Kettle. 

A modified steam-jacketed kettle can be made out of the present 
fire-heated kettles by lining them with steam coils suspended from the 

Round Roofer's Kettle. The kettle shown in Fig. 69 is used 
mostly by roofers in exactly the same manner as the asphalt and heat- 
ing mastic kettles. This kettle is strongly constructed, handy 
for small jobs and for patching purposes. These roofer's kettles 
are generally built and used in sizes of 20, 30 and 50 gallons capacity. 

Rectangular Roofer's Kettle. The roofer's kettle shown in Fig. 
70 is made rectangular in form and in capacities of 50, 100 and 150 
gallons. They are built of No. 14 sheet steel, riveted and braced 
in all corners with angle iron. The tank is made with bottom semi- 
cylindrical in form, separate from fire box, thus facilitating repairs 
in replacing burnt bottoms. The furnace is reinforced on the inside 


by an extra thickness of No. 14 steel to resist the heat. The kettles 
are usually provided with four carrying handles attached to the side 
sheets as shown. 

Portable Heating Kettle (Drag Type). In Fig. 71 is shown a 
large portable heating kettle mainly used by roofers. It is very 
serviceable, especially the davit, which greatly facilitates handling 
barrels. In warm weather the heat from the melted bitumen in 
the kettle is sufficient to make the bitumen flow from the bung of the 
barrel, which is placed so that it opens downward. This keeps the 
barrel intact which may then be used again. The kettle may be had 
in capacities of 150 to 500 gallons. 

Portable Heating Kettle (Wagon Type). The portable heater 
shown in Fig 72 is used chiefly by roofers. This type of heater is 

FIG. 70. Stationary Roofer's Kettle. (End View has Outside Jacket Removed.) 

intended for long hauls and small jobs. The bitumen can be heated 
while being hauled to the work. In places where the municipal 
authorities will not allow a thoroughfare to be blockaded by station- 
ary kettles, this is found a desirable outfit. The space back of the 
driver's seat is arranged for holding wood, having sufficient space 
for about two days' supply. There is also a rack for carrying pails, 
dippers, mops, etc. The heating tank is provided with a hinged 
cover. This type of heater usually comes in sizes of 100 to 150 
gallons capacity. 

Portable Heating Kettle (Hand Cart Type). The portable kettle 
illustrated in Fig. 73 is much used by roofers and waterproofers, 
particularly the latter, because it is made in as small capacities as 
desired. By the use of this type of small portable heating kettles, 
the stationary mixing kettles can be almost any distance from the 



work, and the bitumen, or mastic, can, by means of them, be trans- 
ported hot from the heating or mixing kettles to the place of applica- 
tion. The smaller portable kettles need no projecting chimneys. 

FIG. 71. Portable Asphalt and Tar-heating Kettle with Davit Attachment. 

The furnace is equipped with sheet steel bottom, of No. 12 gauge, 
and is tongue-riveted to the tank. It has a wrought-iron handle 
provided with a foot rest in front, and a discharge pipe from the tank 
in the rear, 


Combination Tar and Gravel Heater. A tar and gravel heater, 
similar in construction to but usually larger than the portable 

FIG. 72. Wagon Type of Tar and Asphalt Heater. 

kettle shown in Fig. 73 is used by roofers and general waterproofers 
alike. On top of the heater are two doors, one enclosing a round- 

FIG. 73. Hand-portable Type of Tar, Asphalt, and Mastic-heating Kettle. 

bottom tank in which the bitumen is heated, and the other an inclined 
container for the sand or gravel which is drawn out as needed from an 


upper door in the end. A lower door encloses the fire box. In the 
rear of the heater is a spout for drawing the bitumen. The heater 
can be transported from place to place by attaching it to a wagon. 
The standard kettle has a capacity of 70 gallons of bitumen and 
gravel. This heater will produce one ton of hot, dry gravel per hour. 


Roofing Mops. The mops shown in Fig. 74 are used for roofing 
and waterproofing alike. They are made of a cotton warp, attached 

FIG. 74. Roofing and Waterproofing Mops. 

to wooden handles 4 feet long, the weight and length of warp being 
as follows : 

3-ounce cotton warp, 5J inches long. 

12-ounce cotton warp, 9J inches long. 

20-ounce cotton warp, 12 inches long. 

32-ounce cotton warp, 15 inches long. 

The two smallest are used chiefly for roofing, the two longest, 
chiefly for general waterproofing. 

The general practice is to buy bales of cotton warp, and make the 
mops on the work, as needed. 


Mastic Stirrers. Fig. 75, A, illustrates an efficient type of mastic 
stirrer. for round-bottom kettles. Other types consist of a long- 
handled paddle whose end is shaped like an oar; or an iron rod 
terminating in a flat triangle as shown in Fig. 75, B. This is best 
suited to the cylindrical type of mixing kettle. Another type of 
stirrer is made of a coffin-shaped piece of sheet iron perforated with 
1-inch holes, and securely fastened to the end of a long pole. Some- 
times a strong flat stick, picked up on the work, is used. This type, 
however, as well as the oar or coffin-shaped stirrers, are not efficient 
tools. A modification of the stirrer shown in Fig. 75, A, consists in 
making the frame square, but as the majority of kettles used are 
round-bottomed, this also does not make an efficient stirrer. In the 
stirrer shown in the figure the handle is made of wood inserted 
into an iron rod, which terminates in a ring, the hole of which is 

FIG. 75. 

A. Paddle Type of Mastic Stirrer, (Hnch Wire Mesh). 

B. Stirring Rod. 

occupied by a f- or |-inch iron- wire screen of J-inch mesh securely 
fastened to the ring. 

Dipper and Pouring Pail. The dipper and pouring pail shown in 
Fig. 65 are usually made of galvanized sheet iron, or other sheet 
metal, in several sizes and capacities, the most common of which 
being the 3-gallon type. They are both reinforced with a heavy 
wire band at the top. The base of the ferrule of the best dippers is 
riveted to the bottom. The dippers have wooden handles from 
6 to 8 feet long. The type of pouring pail shown in Fig. 76, A, may 
serve also as a melting pot and when so used, is placed in a suitable 
portable furnace, like a salamander. The seams in this kettle are 
rolled and the top is divided and hinged across the middle. 

Asphalt Smoother. The asphalt smoothers shown in Fig. 76, B, 
have but a limited use in waterproofing work. They are, however, 
very efficient for the limited purpose for which they are applicable, 



especially the very small ones, whose base is about 3 by 4 inches 
(curved like the larger smoothers) with short iron handles. They 
are heated and used to soften the exposed ends and laps of bituminous 
membranes to insure a good waterproof joint between old and new 

work. The manner of using the smoother for waterproofing is the 
same as in paving work. The larger smoothers are made of cast 
iron in two sizes, their faces being ground smooth and to a curve. 
They are provided with handles made of IJ-inch pipe, bent at the 
upper end, and welded to a steel stub cast in the head of the smoother. 


Gasoline Torch. The torch shown in Fig. 76, D, is the one most 
generally used for heating laps and small surfaces of old waterproofing 
of the membrane and surface coating types. It is sometimes also 
used for heating concrete in the mixer, in freezing weather, where it 
is very effective, and helpful in producing good concrete in cold 
weather. This torch produces a blue flame of great heat efficiency. 
The shipping weight of this type of torch is about 4| pounds. 

FIG. 77. Method of Drying and Sieving Sand; Typical Arrangement of Fire- 
heated Kettles for Making Mastic. (Note Yoke for Carrying Pails of 
Hot Pitch or Mastic.) 

Asphalt Cutter. In Fig. 76, C, is shown an asphalt cutter widely 
used where asphalt or hard tar products are employed in construction. 
With it, wooden barrels and tin drums, in both of which the pitch 
and asphalt are received on the work, are readily cut up, exposing 
the materials. These are in turn cut up into small pieces for easy 
handling. The cutters are made of tool steel, with tempered edges, 
thus giving long service before the tool has to be repaired. The 
length of cutter from edge to edge is 20J inches; width of edge 3 
inches; shipping weight of double-edge cutter is 10 pounds. 



Gravel Heating Pan. The gravel heating pan shown in Fig. 
76, E, is much used by roofers and general waterproofers. In ser- 
vice it is usually supported by several bricks under each corner 

FIG. 78. Method of Drying, Heating, and Sieving Sand in Large Quantities. 

permitting a wood fire to be built underneath. The sand or gravel 
is spread over the pan, and dried or heated as desired. These pans 
are made of soft steel with riveted sides. The most generally used 
size is 106 inches long, 42 inches wide and 8 inches deep. 


Sand and Gravel Heating Pipe. The pipes shown lying on the 
ground in Fig. 77 are sheet metal, but more usually old, discarded, 
cast-iron water pipes, over 1J feet in diameter. They are used very 
extensively by waterproofers for drying and heating sand and gravel 
in large quantities. Where possible, the sand or gravel is dumped 
directly on the pipes as shown, otherwise these materials are shoveled 
on until a pile, 2 or 3 feet high, rests on them. A wood fire is built 
inside of these pipes, in which a 
natural draft is always present. 
When the sand is sufficiently heat- 
ed, it is usually screened (see man 
with shovel at wheelbarrow) before 
being used. Tig. 78 shows an 
improvised pipe furnace for dry- 
ing, heating and screening sand in 
large quantities. 

Salamander. The salamander 
shown in Fig. 79 is used for 
drying bricks which are intended 
for brick-in-mastic waterproofing, 
and also for heating enclosed 
areas to be waterproofed' in cold 
weather. Salamanders are usually 
made of J- or j^-inch steel plate 
and equipped with heavy cast-iron 
gratings. They come in several 
sizes, the most common being 17 
inches in diameter by 20 inches 
high and 20 inches in diameter by 
24 inches high. 

Wheel Barrow. A steel-tray wheel barrow, besides serving its 
obvious purpose, is very commonly used for volume measurements 
of the mineral ingredients entering into the making of mastic for 
waterproofing. Such a wheel barrow is usually constructed of 
Nos. 16 to 12 gauge steel, and in capacities of 2J to 6 cubic feet. 

Concrete Tampers. The tampers shown in Fig. 80, A , B and C, 
are designed to insure a compact concrete mass. The tamping process 
is really a slicing and cutting process for the purpose of letting air 
bubbles out of the concrete. Ordinary tamping is done by a form 
of tamper shown in Fig. 80, B. For facing work, the gridiron tamper 
in Fig. 80, A, gives excellent results. The tamper shown at C is 
constructed with two spacings. 

FIG. 79. Iron Salamander Used for 
Drying and Heating tricks. 



Trowels and Floats. Fig. 81, A, represents the usual form of 
trowel used for pointing between copings, or flashings and walls, etc. 
Fig. 81, B, represents the usual form of trowel used in applying and 
smoothing waterproofed plaster and mortar. Fig. 81, C, is a wooden 
spreader or float generally used for spreading and floating bitumi- 
nous-mastic floors, sheet mastic waterproofing, etc. It is about 1 


FIG. 80. Concrete Tampers. 

foot long, 4 inches wide and 2 inches thick, with smooth and true 
faces all around. In using the float its beveled edge is held forward 
and applied in a somewhat diagonal direction while pressure is brought 
to bear on the handle. It is not possible to secure the same fine, 
finished surface on these materials with an iron trowel or smoother. 
Cores for Felt and Fabric Rolls. Waterproofing felt and fabric is 
put up in rolls so as to make handling easy (see Fig. 120). In ship- 


ping, hauling and storing, these rolls \vould be badly crushed, warped, 
bent and wrinkled but for the solid core on which they are usually 
wound. The cores are sometimes made of paste-board roll and 
slat crates but most often of solid square or round sticks. Water- 

FIG. 81. 

A. Mastic trowel. 

B. Mortar Trowel. 

C. Wood Spreader or Float for Mastic Floors. 

proofing felts are often rolled up without any cores, but waterproofing 
fabric can never be handled without cores. The various types 
employed are illustrated in Fig. 82. 

Mechanical Brick Heater. A practical and economical method 
of drying and heating bricks is by the use of an iron furnace, or 





Wood Crate 
3 -2" Blocks 

' Box Core 
3"x 3" 

FIG. 82. Types of Cores upon which Felt and Fabric is Rolled for Shipping. 

heater.* This heater consists of a rectangular sheet-iron box about 
4 by 4 feet and 8 feet high. On opposite sides and .at different 
elevations it has rectangular openings 10 or 12 inches high and 4 feet 
wide. To the bottom of these openings are attached hinged doors. 
* Designed and used by the New York Roofing Co. 


Gratings inclined about 45 degrees connect with the bottoms of the 
door openings. A low, flat, iron, box-like salamander placed on the 
ground under the lowest grating completes the equipment. The 
process of heating the bricks is commenced by kindling a charcoal 
fire in the salamander, and placing bricks on the first grating through 
the most elevated door connected therewith, the lower one remaining 
closed. Then bricks are placed on the second grating and finally 
on the third grating. By the time this is done the bricks on the first 
grating are sufficiently dry and warm and may be dumped from the 
heater into a wheel barrow or other conveyance by opening the door 
on the lower level. Then the second and third doors above are 
opened in succession, allowing the bricks to fall out automatically. 
With this heater, 14,000 to 20,000 bricks per day can be dried and 
heated to quite a high temperature and without soot. 


Fig. 83 illustrates a modern type of cement gun. A sectional 
view is shown in Fig. 84. This type is built to withstand air-pressure 
up to 60 pounds per square inch. The following description will 
aid in understanding its operation: 

The tanks marked in the figure as 4 and 5 are steel sheet, welded 
on both sides and riveted to flanges as shown. The tank is hinged 
to the cast-iron base to permit access to the interior for cleaning. 
The cone valves 3 and the feed wheel 6 are of cast iron with a 
smooth finish. The air motor 9 drives the feed wheel through a 
worm and worm gear. The dry materials, mixed in the proper 
proportions, are placed in both tanks through the open valves, 
before any air is turned on. Then the upper cone valve 3 is closed 
by means of lever 2 and compressed air is admitted through cock A, 
which holds the cone valve in place. Cock B is then opened, admit- 
ting air through a gooseneck and the outlet valve 8. Cock C is then 
opened which makes the feed wheel 6 revolve, and the material in 
each pocket of same, as it registers with the gooseneck, is blown out 
through valve 8, into the material hose attached thereto, to the 
nozzle where the water from a separate base is added. 

To recharge the machine it is not necessary to stop it, as the lower 
cone valve 3 is held in the position shown when the air in the upper 
tank is exhausted. The upper cone valve then opens and a new 
charge is put into the machine. The operation of this machine 
must be continuous while the mortar is being applied. 


FIG. 83. Cement Gun. (Height, 69 Inches; Floor Space, 42 by 44 Inches; 

Weight, 1350 Ib.) 




Grouting machines are manufactured in several sizes to with- 
stand presures up to 600 pounds per square inch. They can be 

made to stir the grout mechanically, or by compressed air. Fig. 85 
shows a small-sized patented grout mixer designed for mixing grout 
by compressed air only. The space occupied by such a machine is 


about 3 by 3 feet and 4 feet high. The average batch capacity is 
about 4 cubic feet. 

Referring to its operation, B is the compressed air inlet. Valves 
C, D, and F are closed and door A opened. The sand and cement 
are charged through the door A, and a measured quantity of water is 
admitted through A by means of a hose. Then the door A is closed. 
Valve D is now opened, allowing the compressed air to blow in at 
the bottom to mix the grout. This keeps the mixture agitated and 

Blow off when Mixing 


Grout Discharge 
to Place, 

FIG. 85. Section of Ransome-Caniff Grout Mixer. (Patented.) 

prevents the sand and cement setting into and choking the outlet, 
pipe G. During this operation, the blowoff valve K must be open. 
When the batch is mixed, valves K and D are closed, and valve C 
opened. When the batch is to be ejected, valve F, controlled by 
handle H, is opened and the grout discharged through a hose attached 
to outlet G. Then valves C and F are closed, the excess pressure 
allowed to blow off through valve K, when the door A drops open, 
and the machine is again ready to be charged. 


Necessity of Testing Waterproofing Materials. Testing of 
waterproofing materials is necessary to insure good and uniform 
products. Representative specimens of materials to be used should be 
tested in the laboratory for comparison with specified requirements. 
Analysis should be made when any doubt exists regarding the true 
nature of the material. This is especially true of tar and bituminous 
compounds and proprietary products, as has, no doubt, become 
evident. Some practical field tests may reveal certain undesirable 
qualities, but laboratory tests can often be relied upon to reveal 
more, and should not be neglected. 

To know the properties of materials is not more essential than 
knowing how to test for these properties, at least in a practical way. 
In the light of present-day knowledge of waterproofing materials, 
it is necessary for the engineer to be acquainted with methods of 
testing and to be able to correctly interpret results of tests. Of 
equal importance to the tester is a knowledge of the significance of 
the tests called for in specifications. For this, however, both techni- 
cal knowledge and experience are necessary. 

In this chaper technical tests on pitch and asphalt are briefly 
described and their significance explained; also tests and results 
on the impermeability of plain and waterproofed concrete and cement 
mortars, and certain practical tests related to general waterproofing 
are described. The results of some of the tests described herein 
will make evident certain statements of facts made in other chapters. 
Particular attention is directed to the many practical tests as show- 
ing the logical way of aiding the engineer's judgment in arriving at 
conclusions in regard to the adaptability of some materials for 
unusual purposes. , Waterproofing involves comparatively little 
theory, which , perhaps, explains its slow progress, and its continu- 
ance as an art rather than as an exact science. 




The bitumens form the most important and widely used. materials 
for waterproofing. It will be well, therefore, to describe some of the 
laboratory tests made on this class of materials in more detail than 
the others. 

The following list of tests includes all those of more or less value 
in determining and recording the characteristics of tar and bituminous 
materials used for waterproofing purposes: 

Coal-tar Pitch. Specific . gravity at 60 deg. Fahr. (15.5 deg. 
Cent.) or 77 deg. Fahr. (25 deg. Cent.). 

Flash point. 

Solubility in carbon disulphide (082). 

Penetration (consistency) at 39 deg. Fahr. (4 deg. Cent.) and 
77 deg. Fahr. (25 deg. Cent.). 

Flow point. 


Loss on evaporation at 325 deg. Fahr. (163 deg. Cent.). 

Penetration (consistency) of residue at 39 deg. Fahr. (4 deg. 
Cent.), 77 deg. Fahr. (25 deg. Cent.). 

Melting-point of residue. 

Free carbon content. 

Ash test. 

Asphalt. Specific gravity at 60 deg. Fahr. (15.5 deg. Cent.), 
or 77 deg. Fahr. (25 deg. Cent.). 

Flash point. 

Solubility in carbon disulphide (082). 

Solubility in carbon tetrachloride (CCU). 

Solubility in petroleum naphtha. 

Penetration (consistency) at 39 deg. Fahr. (4 deg. Cent.) and 77 
deg. Fahr. (25 deg. Cent.). 


Ductility at 39 deg. Fahr. (4 deg. Cent.) and 77 deg. Fahr. (25 
deg. Cent.). 

Fixed carbon content and paraffin content.* 

Loss on evaporation at 325 deg. Fahr. (163 deg. Cent.). 

Penetration (consistency) of residue at 39 deg. Fahr. (4 deg. 
Cent.), 77 deg. Fahr. (25 deg. Cent.). 

Melting-point of residue. 

* The fixed carbon and paraffin content tests are of little practical value, 
but are included here because this fact is not yet generally so accepted. 


Ductility of residue at 39 deg. Fahr. (4 deg. Cent.), 77 deg. Fahr. 


Specific Gravity. Specific gravity is mainly used to differentiate 
between different tars or bitumens and as a means of identification. 
The temperature at which the tar or bitumen is tested is a governing 
factor in the determination of its specific gravity. This temperature, 
which has been standardized, and always accompanies the specific 
gravity value, is either 60 or 77 deg. Fahr. (15.5 or 25 deg. Cent.), 
selected arbitrarily. The specific gravity of the semi-solid asphalts 
varies with their origin, mode and degree of refinement, and lies 
between .87 and 1.21 at 77 deg. Fahr. The specific gravity of the 
tars varies with the method of manufacture and degree of distilla- 
tion, and lies between 1.10 and 1.25 at 60 deg. Fahr. 

The specific gravity* of thin fluid pitches or bitumens is usually 
determined by the hydrometer method, which consists in selecting 
the proper hydrometer, inserting it in the material at 77 deg. Fahr. 
(25 deg. Cent.) and reading the specific gravity off the scale to the 
third decimal place. 

The specific gravity of hard, solid, bitumens is determined by the 
displacement method, i.e., suspending a small piece of the bitumen 
by means of a silk thread from the hook of one of the pan supports 
of an analytical balance, about 1J inches above the pan and weighed. 
This is weight " a." It is then weighed immersed in water at 25 deg. 
Cent, and this weight is called " 6." The specific gravity of the. 


bitumen is then equal to 


The specific gravity of viscous and semi-solid bitumens is usually 
determined by the pyknometer method, which requires the following 

A large metal kitchen spoon, a steel spatula or kitchen knife, 
Bunsen burner and rubber tubing, one 250-c.c. low-form glass 
beaker, a chemical thermometer reading from 18 deg. Fahr. to 
230 deg. Fahr. (-10 deg. Cent, to 110 deg. Cent.), a special 
pyknometer (Fig. 86), an analytical balance, capacity 100 grams, 
sensitive to 0.1 mg. 

The pyknometer consists of a fairly heavy, straight-walled glass 
tube, 70 mm. long and 22 mm. in diameter, carefully ground to 
receive an accurately fitting solid glass stopper with a hole of 
1.6 mm. bore in place of the usual capillary opening. The lower 
part of this stopper is made concave in order to allow all air 

* Methods for the examination of bituminous road materials. Bulletin No. 
314, U. S. Dept. of Agriculture. 


j n i 

bubbles to escape through the bore. The depth of the cup-shaped 
depression is 4.8 mm. at the center. The stoppered tube has a 
capacity of about 24 c.c. and when empty weighs about 28 grams. 

When working with semi-solid bitumens which are too soft to be 
broken and handled in fragments, the following method of deter- 
mining their specific gravity is employed. The clean, dry pyknometer 
is first weighed empty and this weight is called " a." It is then filled 
in the usual manner with freshly distilled water at 77 deg. Fahr. 
(25 deg. Cent.), and the weight is again taken and called " b." 
A small amount of the bitumen should be placed in the spoon and 
brought to a fluid condition by the gentle appli- 
cation of heat, with care that no loss by 
evaporation occurs. When sufficiently fluid, 
enough is poured into the dry pyknometer, 
which may also be warmed, to fill it about 
half full, without allowing the material to 
touch the sides of the tube above the desired 
level. The tube and contents are then allowed 
to cool to room temperature, after which the 
tube is carefully weighed with the stopper. 
The weight is called " c." Distilled water, at 
77 deg. Fahr. (25 deg. Cent.), is then poured 
in until the pyknometer is full. After this the 
stopper is inserted, and the whole cooled to 77 
deg. Fahr., by a 30-minute immersion in a beaker 
of distilled water maintained at this tempera- 
ture. All surplus moisture is then removed 
with a soft cloth, and the pyknometer and con- 
tents are weighed. This weight is called " d." 
From the weights obtained the specific gravity of the bitumen may 
be readily calculated by the following formula: 

Specific gravity at 77 deg. Fahr./77 deg. Fahr. = - - ^ ^- -. 


Flash Point. The flash point of an asphalt determines the pos- 
sibility of explosions in the melting kettles and general fire risk. It 
is the temperature at which volatile oils are given off in a gaseous 
state and which may catch fire. This is guarded against by keeping 
the flash point as high as possible, that is, refining the asphalts 
so as to exclude as much volatile oil as practicable. An asphalt 
with a flash point below 400 deg. Fahr. is not ordinarily used. 

Although for ordinary purposes the open-cup method for deter- 
mining the flash and burning-points of tars and bituminous materials 

Uged to obtain 
Specific Gravity of 



is reasonably accurate, the closed-cup method described below is to 
be preferred. 

The oil tester consists of a copper oil cup (Fig. 87) having a 
capacity of about 300 c.c. It is heated in a water or oil bath by 
a small Bunsen flame. The cup is provided with a glass cover, 

carrying a thermometer and a hole 
for inserting the testing flame. The 
testing flame is obtained from a jet 
of gas passed through a piece of glass 
tubing, and is about 5 mm. long 1 . 

The flash test is made as follows: 
The oil cup is first removed and the 
bath filled with water or cottonseed 
oil, depending on the volatile nature 
of the material tested. The oil cup 
is replaced and filled with the material 
to be tested to within 3 mm. of the 
flange joining the cup and the vapor 
chamber above. The glass cover is 
then placed on the oil cup and the 
thermometer adjusted so that its bulb 
is just covered by the bituminous 
material. The Bunsen flame is then 
applied in such a manner that the 
temperature of the material in the cup 
is raised at the rate of about 9 deg. 
Fahr. (5 deg. Cent.) per minute. 
From time to time the testing flame 
is inserted in the opening in the cover 
to about half way between the surface 
of the material and the cover. The 
appearance of a faint bluish flame 
over the entire surface of the bitu- 
minous material will show that the 
flash point has been reached and the 

temperature at this point is taken. The burning-point of the material 
may be obtained by removing the glass cover and replacing the 
thermometer in a wire frame. The temperature is raised at the same 
rate and the material tested as before. The temperature at which 
the material ignites and burns is taken as the burning-point. 

Solubility in Carbon Bisulphide. In nearly all asphalts there is a 
pertain quantity of insoluble bitumen present. This insoluble bitu- 

Fia. 87. New York State Board 
of Health Oil Tester. 


men lessens the cementing value of the remainder of the asphalt, 
raises its melting-point, causes it to become brittle at low tempera- 
tures, and otherwise impairs its suitability for waterproofing purposes. 
A pure asphalt of uniform consistency, containing the highest per 
cent of soluble bitumen, is the most workable and durable, and the 
solubility test in carbon disulphide aids the chemist in deciding 
these points. A determination of the amount of pure bitumen 
present in any specimen by this test should not show less than 95 
per cent. 

The test consists in dissolving the bituminous material in car- 
bon disulphide, and recovering any insoluble matter by filtering 
the solution through an asbestos felt filter. This felt is carefully 
placed in the bottom of a Gooch crucible, washed several times with 
water, and drawn firmly against the bottom of the crucible by 
suction. The crucible used for this determination should be 4.4 
cm. wide at the top, tapering to 3.6 cm. at the bottom, and 2.5 cm. 
deep. The crucible containing the filter is first placed in a drying 
oven for a few minutes, removed and ignited to red heat over a 
Bunsen burner, cooled in a desiccator and weighed. 

Two grams of bituminous material is then placed in a flask, 
which has been weighed previously, and the accurate weight of the 
sample obtained. One hundred cubic centimeters of chemically 
pure carbon disulphide is poured into the flask, in small portions, 
with continual agitation, until all lumps disappear and nothing 
adheres to the bottom. The flask is then corked and set aside 
for fifteen minutes to allow settlement of the insoluble material. 

This solution should then be decanted through the felt filter in 
the Gooch crucible without stirring up any precipitate that may have 
settled down. The sides of the flask should now be washed down 
with a small quantity of carbon disulphide, after which the whole is 
poured on the felt and suction applied until there is practically 
no odor of carbon disulphide in the crucible. The crucible and con- 
tents should then be dried at 212 deg. Fahr. (100 deg. Cent.) for 
about twenty minutes, cooled in a desiccator and weighed. The 
weight of insoluble matter may include both organic and mineral 
matter. The former must be burned off by ignition at a red heat, 
thus leaving a mineral matter or ash which is weighed when cool. 
The difference between the total weight of the material insoluble in 
carbon disulphide and the weight of substance taken equals the 
total bitumen. The percentage weights are calculated as total 
bitumen, and insoluble matter, on the basis of the weight of material 
taken for analysis. Further detailed information for those partic- 


ularly interested in this test will be found in the Transactions of 
the American Society of Civil Engineers, Vol. 82, p. 1450 (1918). 

Solubility in Carbon Tetrachloride. The solubility test in carbon 
tetrachloride shows whether or not the asphalt has been overheated 
in refining. The greater the percentage of insoluble bitumen, the 
greater the overheating; in other words, it indicates the amount 
of incipient destruction that the asphalt has undergone. This test 
also determines the amount of other impurities present in the asphalt. 
The amount of pure bitumen (the soluble part) present in any given 
specimen should not be less than 95 per cent. 

The test is conducted in exactly the same manner as described 
for " Solubility in Carbon Bisulphide," except that 100 c.c. of 
chemically pure carbon tetrachloride is used in place of carbon 
disulphide, and the percentage of bitumen insoluble in carbon tetra- 
chloride is reported on the basis of the bitumen taken as 100, the 
quantity of the bitumen having been determined by the method 
previously described. 

Solubility in Petrolic Ether* (Petroleum Naphtha). The solu- 
bility test in petrolic ether is to determine the per cent of petroline 
present in asphalt, which material is considered to give the viscous or 
adhesive quality to the asphalt. This test also shows the amount 
of true bitumen in the asphalt, i.e., the amount of hydrocarbon 
called " asphaltine." Asphaltine is supposed to possess the greatest 
durability and resistance to deteriorating agents ; it also gives hard- 
ness to the asphalt. The petrolic ether dissolves out the petroline, 
leaving the insoluble asphaltine. A reasonably good asphalt will be 
greater than 66 per cent soluble in petrolic -ether of 88 deg. Baume. 

This determination is made in the same general manner as the 
test for solubility in carbon disulphide, except that 100 c.c. of 86 
to 88 deg. Baume paraffin naphtha, at least 85 per cent distilling 
between 95 and 149 deg. Fahr. (35 and 65 deg. Cent.) is employed 
as a solvent instead of carbon disulphide. Considerable difficulty 
is sometimes experienced in breaking up some of the heavy semi- 
solid bitumens; the surface of the material is attacked, but it is 
necessary to remove some of the insoluble matter in order to expose 
fresh material to the action of the solvent. It is, therefore, ad- 
visable to heat the sample after it is weighed, allowing it to cool 
in a thin layer around the lower part of the flask. If difficulty 
is still experienced in dissolving the material, a rounded glass rod 
will be found convenient for breaking up the undissiolved particles. 
Not more than one-half of the total amount of naphtha required 
*U. S. Dept. of Agriculture. Bulletin No. 314, Dec. 10, 1915, p. 28. 


should be used until the sample is entirely broken up. The balance 
of the 100 c.c. is then added, and the flask is twirled a moment in 
order to mix the contents thoroughly, after which it is corked and 
set aside for thirty minutes. 

In making the filtration the utmost care should be exercised to 
avoid stirring up any of the precipitate, in order that the filter may 
not be clogged and that the first decantation may be as complete 
as possible. The sides of the flask should then be quickly washed 
down with naphtha and, when the crucible has drained, the bulk of 
insoluble matter is brought upon the felt. Suction may be applied 
when the filtration by gravity almost ceases, but should be used 
sparingly, as it tends to clog the filter by packing the precipitate 
too tightly. The material on the felt should never be allowed 
to run entirely dry until the washing is completed, as shown by the 
colorless filtrate. When considerable insoluble matter adheres to 
the flask no attempt should be made to remove it completely. In 
such cases the adhering material is merely washed until free from 
soluble matter, and the flask is dried with the crucible at 100 
deg. Cent, for about one hour, after which it is cooled and weighed. 
The percentage of bitumen insoluble is reported upon the basis of 
total bitumen taken as 100. 

The difference between the material insoluble in carbon disul- 
phide and in the naphtha is the bitumen insoluble in the latter. 
Thus, if in a certain instance it is found that the material insoluble 
in carbon disulphide amounts to 1 per cent and that 10.9 per cent 
is insoluble in naphtha, the percentage of bitumen insoluble would 
be calculated as follows: 

Bitumen insoluble in naphtha 10.9 1 9.9 

= = = 10 per cent. 

Total bitumen 100-1 99 

Penetration Test.* Consistency of an asphalt is a measure, 
especially in commerce, of its hardness and softness at various tem- 
peratures, and this property is usually determined by the penetra- 
tion test. The greater the penetration, the softer is the bitumen. 
All coal-tar pitches and asphalts have the property of being softened 
by heat and hardened by cold, hence it is necessary to determine to 
what degree they are so affected. It is evident that the less a pitch 
or asphalt is changed in consistency by changes in temperature, the 
more desirable it is as a waterproofing material. But what the 
penetration of coal-tar pitch or asphalt for waterproofing should be 
depends largely on the specific use they will be put to. 

* Journal of Industrial Engineering Chemistry, Vol. 6, No. 2, February, 1914. 



The test is performed on a standard machine called a pene- 
trometer. Penetrometers consist essentially of a needle of specified 
size (Roberts No. 2) fixed in a rod, the rod and needle being of, 
or loaded to, definite weights. A clamp on the body of the instrument 
holds the rod with the needle, which, on being released, allows the 
latter to penetrate as nearly as possible without friction. A device 
for measuring the amount the needle has penetrated after it has been 
released for a specified time and again grasped by the clamp is also 

included. (The Dow pene- 
trometer is constructed on 
this basis.) The penetration 
is expressed in hundredths of 
a centimeter, though it is not 
always designated so. Pene- 
trations are most commonly 
made at 77 deg. Fahr. (25 deg. 
Cent.), with the needle loaded 
to 100 grams penetrating for 
five seconds. In order to 
ascertain the extent a bitumen 
will harden when chilled to 32 
deg. Fahr. (0 deg. Cent.), 
penetrations are frequently 
made at this temperature with 
the needle loaded to 200 grams 
penetrating for one minute. 
A new form of penetrometer 
electrically controlled and 
timed is shown in Fig. 88. A 
new and much more accurate 
machine of this type, called a 
consistometer, in which the 
needle is replaced by a rod and 

penetration or consistency is measured by volume displacement, is 
described in the Proceedings of the American Society for Testing 
Materials, Vol. 11, 1911. For a more detailed description of the 
Penetration Test see Transactions of the American Society of Civil 
Engineers, Vol. 82, p. 1454 (1918). 

FIG. 88. Electrically Controlled 



There are nine or more different methods of obtaining the melt- 
ing-point of bitumen, giving results varying by as much as 30 and 
40 deg. Fahr. What causes the real trouble, though, is that chemists 
are at variance as to which method is most nearly correct. The 
technique of the methods differs so considerably that it is difficult 
or impossible to note any definite relation between the results obtained 
with each method. 

But, as a matter of fact, all methods are more or less incorrect. 
They all depend on varying, arbitrary factors and special technique. 
They all attempt to determine the melting-point of materials that 
have no melting-point. Pitch and asphalt have no melting-point 
for the reason that they are composed of complex mixtures of hydro- 
carbons, which are of indefinite consistence and specific gravity. 

Were it possible to measure in absolute units the fluidity of a 
-pitch or asphalt, this would furnish the ideal method, but as this 
seems unattainable it would be advisable to select one method 
possessing the most practicable apparatus and technique. Or per- 
haps a new method could be evolved embodying the good features 
of all the present ones. Up to the present time nothing has been 
done to co-ordinate these methods. 

However, one thing is certain, any method, the results of which 
are influenced by the specific gravity of the material tested is 
wrong. This refers particularly to what is known as the " Cube-in- 
water Method," described below. For instance, the average specific 
gravity of asphalt derived from paraffin petroleum is 0.961; from 
asphaltic petroleum, 1.004. The buoyant effect of the material 
whose specific gravity is so nearly unity is obvious, hence no worth- 
while melting-point is found by the cube-in-water method. This 
is equally the case when applied to coal-tar pitch, whose specific 
gravity varies with the method of manufacture or reduction as 
follows: * Gas-house tars, 1.22; coke-oven tars, 1.18; water-gas 
tars, 1.10. A standard method of finding the melting-point of 
bitumens ought to be established for general use for all laboratories; 
or else it should become the general practice to state the method 
whenever the melting-point of a bitumen is given, otherwise, as at 
present, this value is practically meaningless. 

Nearly all the other properties of pitch or asphalt are modified 
by the melting-point. It is, in fact, a measure of the fluidity, con- 

* " Some experiments on Technical Bitumens," by S. R. Church, American 
Society for Testing Materials, April, 1915. 


sistency and ductility of these materials. But because it is an 
arbitrary value, dependent to a great extent on the method of test, 
it is not as reliable as its importance warrants. The nine methods 
explained below, are more or less used in industrial plants and 
laboratories, but no one method predominates. These are: 

1. Ring-and-ball Method. 

2. Cube-in-air Method. 

3. Cube-in-water Method. 

4. Kraemer-and-Sarnow Method. 

5. New York Testing Laboratory Method. 

6. Mabery-Sieplein Method. 

7. Richardson Method. 

8. General Electric Method. 

9. Drop Point Test. 

Ring-and-ball Method. The apparatus of the C. I. Robertson 
or the ring-and-ball method consists of a brass ring f inch in diam- 
eter, J-inch deep, ^-inch wide; a steel ball f inch in diameter, 
weighing 350 grams; a standard thermometer; a glass beaker, 
about 600-c.c. capacity. The test is made as follows: 

Press the ring full of the bitumen, cutting it off slightly with a 
hot knife. Place the ball in the center of the ring and suspend 
the apparatus in a beaker of water, the ring and ball being about 
1 inch from the bottom of the beaker; also suspend a thermometer 
in the beaker of water to the same depth. Heat up at the rate of 
9 deg. Fahr. (5 deg. Cent.) per minute. The melting-point is that 
temperature at which the ball drops through the ring (and reaches 
the bottom of the beaker). The bitumen in the ring usually sags 
down before the melting-point is reached, but the temperature of 
the water at the time the ball reaches the bottom of the beaker 
is the temperature recorded as the melting-point. 

For testing bitumen having a melting-point above 110 deg. 
Fahr. (43 deg. Cent.) the sample should first be cooled to 50 or 77 
deg. Fahr. (10 or 25 deg. Cent.). For testing bitumen having a 
melting-point above 210 deg. Fahr. (99 deg. Cent.) the sample should 
be cooled to 60 or 100 deg. Fahr. (15.5 or 38 deg. Cent.). 

Cube-in-air Method. The material under examination should 
be melted in a spoon by the gentle application of heat until suffi- 
ciently fluid to pour readily. Care shall be taken that it suffers no 
appreciable loss by volatization. It shall then be poured into a 
12.7-mm. (0.5-inch) brass cubical mold, which shall have been 
amalgamated with mercury and shall be placed on an amalgamated 


brass plate. The hot material shall slightly more than fill the mold, 
and, when cooled, the excess shall be cut off with a hot spatula. 

After cooling to room temperature, the cube shall be removed 
from the mold and fastened on the lower arm of a No. 10 wire (B. and 
S. gauge), bent at right angles at one end and suspended beside a 
thermometer in a covered Jena glass beaker having a capacity of 
400 c.c. (13.526 ounces), which shall be placed in a water bath, 
or, for high temperatures, a cottonseed-oil bath. The wire shall be 
passed through the center of two opposite faces of the cube, which 
shall then be suspended with its base 25.4 mm. (1 inch) above the 
bottom of the beaker. The water or oil bath shall consist of an 
800-c.c. (27.051 ounces) low-form Jena glass beaker suitably 
mounted for the application of heat from below. The beaker in 
which the cube is suspended shall be of the tall-form Jena type, 
without lip. The metal cover shall have two openings. A cork, 
through which passes the long arm of the wire, shall be inserted in 
one hole and the thermometer in the other. The bulb of the ther- 
mometer shall be just level with the cube and at an equal distance 
from the side of the beaker. 

After the test specimen shall have been placed in the apparatus, 
the liquid in the outer vessel shall be heated in such a manner that 
the thermometer registers an increase of 9 deg. Fahr. (5 deg. Cent.) 
per minute. The temperature at which the bituminous material 
touches the bottom of the beaker shall be taken as the melting-point. 
Determinations made in the manner described shall not vary more 
than 3.6 deg. Fahr. (2 deg. Cent.) for successive trials on the same 
material. At the beginning of this test the temperature of both 
bituminous material and bath shall be approximately at 77 deg. 
Fahr. (25 deg. Cent.). 

Cube-in-water Method. The cube-in-water method consists of 
(1) the use of apparatus shown in Fig. 89; (2) the manipulation of 
same, as follows. (For bitumens with a melting-point of 110 deg. 
to 170 deg. Fahr. (43 to 77 deg. Cent.)). A clean, well-shaped J-inch 
cube of the bitumen is formed in the mold, as described under the 
cube-in-air method above, placed on the hook of the No. 12 wire 
and suspended in a 600-c.c. beaker, so that the bottom of the bitumen 
is 1 inch above the bottom of the beaker. The bitumen should 
remain five minutes in 400 c.c. of water at a temperature of 60 deg. 
Fahr. (15.5 deg. Cent.) before heat is applied. Apply heat in such 
a manner that the temperature of the water is raised 9 deg. Fahr. 
(5 deg. Cent.) per minute. The temperature recorded by the ther- 
mometer (which is at the same depth as the bitumen when the test 



is started), at the instant the bitumen touches the bottom of beaker 
is considered the melting-point. For bitumens with a melting- 
point below 110 deg. Fahr. (43 deg. Cent.) the same method can be 
used except that at the start the water should have a temperature 
of 40 deg. Fahr. (4 deg. Cent.). For bitumens 170 deg. Fahr. (77 
deg. Cent.) up, cottonseed oil should be substituted for water, 
otherwise the method remains the same. 

No. 1. Pitch Mould (Special). 
No. 2. Hook; Made of # 12 Copper Wire. 
No. 3. Thermometer. 

FIG. 89. Apparatus for Determining the Melting-point of Bitumen by the 
Cube-in-water Method. 

Kraemer-and-Sarnow Method.* The Kraemer-and-Sarnow 
method of making the melting point test for asphalts, tars, etc., is as 
follows: Some asphalt in a layer 10 mm. thick is melted in a beaker 
contained in an oil bath. Into this is dipped an open-end glass tube 
10 cm. long and 6 or 7 mm. internal diameter. The upper end of 
the tube is closed with the finger, the tube is removed and the 
asphalt is allowed to solidify in the tube while it is held horizon- 
* Peckhan's " Solid Bitumens," p. 272. 


tally and rotated. When the asphalt has set the portion adhering 
to the outside is removed. The length of the column inside the 
tube will be about 5 mm. On top of this is poured 5 grams of 
mercury. The -tube containing the asphalt and mercury is then 
suspended in a beaker full of oil or water resting in another beaker 
also full of oil or water. The inner beaker contains a thermometer, 
the bulb of which stands at the same level as the asphalt. The outer 
beaker is heated by means of a small flame. The temperature of the 

FIG. 90. Apparatus for the Determination of the Melting-point of Bitumen 
by the New York Testing Laboratory Method. 

asphalt and thermometer being thus raised uniformly at the rate of 
9 deg. Fahr. (5 deg. Cent.) per minute. 

The temperature recorded when the mercury falls through the 
layer of asphalt is taken as the melting-point. This method depends 
for its accuracy upon the diameter of the tube, the thickness of the 
asphalt and the height of the mercury in the tube above the asphalt. 

New York Testing Laboratory Method. The air method for 
determining the melting-point of semi-solid or solid bitumens requires 
the apparatus shown in Fig. 90 and described below. 


Outer vessel or container for the glycerine bath, 600. c.c. Griffin 
type Jena beaker. 

Inner vessel of air bath, 200 c.c. tall lipless Jena beaker. 

Chair or support for inner vessel, cut out of r^-inch sheet 

Cover for inner vessel, cut out of sheet aluminum or brass. 

Support for molds, disc of brass with tapped holes for two or 
four molds suspended on three hangers. 

Molds for shaping bitumen. 

Commercial glycerine; standard thermometer; double thickness 
20-mesh iron gauze; iron tripod, stand and clamps; Bunsen or 
alcohol burner. 

The test is performed as follows: One or more of the brass molds, 
standing upon a piece of amalgamated brass or tin, should be filled 
with the bitumen under examination. The bitumen may be softened 
by cautiously heating it in a small casserole or tin box until it is 
sufficiently fluid to be poured into the mold. After trimming off 
the upper surface level with the mold, place the sample in water at 
77 deg. Fahr. (25 deg. Cent.) for about ten minutes. It should then 
be suspended in the air bath of the apparatus and the cover and 
thermometer placed in their proper positions. 

The temperature of the glycerine bath should also be 77 deg. 
Fahr. (25 deg. Cent.) at the beginning of the test. 

The apparatus should stand on double 20-mesh iron gauze, 
supported on an iron tripod, and heated at the rate of 5 deg. Fahr. 
(2.6 deg. Cent.) per minute. The temperature at which the sample 
of bitumen flows from the mold and first touches the bottom of the 
inner vessel is recorded as the melting or flowing point. 

Mabery-Sieplein Method.* The apparatus consists of the 
following parts: 

One Jena beaker, 600 c.c. and one 400 c.c. capacity, tall forms 
without lips. 

One wooden stopper to fit 400-c.c. beaker; stopper to have two 
holes, one of inch diameter, in exact center, one of sufficient size 
to admit thermometer f inch from center. 

One metal shelf, J by 1} by -^ inch thick, in the center of which 
and at right angles to which is fastened a rod of inch diameter. 

Mold which will prepare a tablet of asphalt 1 by \ by f inch. 

One standard gas-filled thermometer reading to 300 deg. Fahr. 
(149 deg. Cent.). 

Liquid medium to serve as bath (such as anhydrous glycerine to 
* Journal American Chemical Society, Vol, 23, p. 16. 


be used for temperature up to 280 deg. Fahr. (138 deg. Cent.), linseed 
oil above 280 deg. Fahr.) A slightly modified apparatus is shown 
in Fig. 91. 

The 400-c.c. beaker is set inside the 600-c.c. beaker, and the 
space between is filled with the proper liquid to expand to approxi- 
mately within | inch of the top of the beaker when heated to 280 


] - Strip of Metal 

Cork. Rubber Gasket 



FIG. 91. Apparatus for Determining the Melting- point of Bitumen by the 
" Mabery-Sieplein " Method. 

deg. Fahr. The f-inch rod supporting the shelf is inserted through 
the central hole in the stopper and set so that the top of the shelf is 
exactly 1 inch from the bottom of the beaker. The thermometer 
is inserted in the other opening and is set so that the top of the 
bulb is | inch above the top of the shelf and the bulb itself is f inch 
from the rod supporting the shelf. 

At least 1 ounce of the sample to be examined is carefully melted 
at as low a temperature as possible, care being taken, however, to see 


that it is sufficiently liquid to completely fill the mold and allow the 
escape of any confined air. The asphalt* is then poured into the 
mold, which has previously been amalgamated by brushing with a 
solution of nitrate of mercury. When the asphalt has cooled the 
specimen is removed from the mold and placed on the shelf in 
such a position that the longest side of the specimen is at right 
angles to the longest side of the shelf, and lies perfectly flat so that 
an equal amount of the specimen extends on either side beyond the 
edge of the shelf. Care should of course be taken that the specimen 
just touches the supporting rod. The apparatus is then heated 
gradually by suitable means, preferably by an electric oven, allow- 
ing at least fifteen minutes for the temperature to reach 120 deg. 
Fahr. (49 deg. Cent.). When this point is reached the temperature 
is increased at the rate of 6 deg. Fahr. (3.3 deg. Cent.) per minute 
until the portions of the specimen extending beyond the sides of the 
shelf have sufficiently softened so that they have dropped to the bot- 
tom. The temperature at which the asphalt just touches the bottom 
of the beaker is the melting-point. 

Richardson or Pellet Method. The melting-point of bitumen 
by the Richardson or Pellet method is determined as follows: A 
thin porcelain dish, about 2| inches in diameter, and with 1^-inch 
sides, filled with clean mercury to a distance of \ inch from the top, 
is placed over a 20-mesh wire gauze and heated by a small flame 
protected from draughts by a chimney. On the surface of the 
mercury is placed a thin microscopic cover-glass, No. 2-0, carrying 
the specimen of asphalt under examination. 

When dealing with hard asphalts that can be ground rather 
coarsely, several fragments, which will pass a 40-mesh sieve and be 
retained on a 50-mesh sieve (about .50 mm. diameter), are spread 
on the glass. This is then placed upon the surface of the mercury, 
covered with a glass funnel, from which the stem has been cut and 
the thermometer passed through the orifice until the bulb is immersed 
in the mercury. It is held in position by a clamp attached to a 
ring-stand on which rests the dish. Under the dish a Bunsen burner 
is placed and regulated to a small flame, or so that the dish is heated 
at the rate of 5.4 to 9 deg. Fahr. (3 to 5 deg. Cent.) per minute. 
In a short time it would be noticed that the specimens will have 
changed from the brown or brownish-black color of the powder to 
that more nearly approaching the original, with a slight rounding 
of the individual grains. On further heating, these globules flow 

* This method is to be used only on asphalt having a penetration less than 
105 at 77 deg. Fahr. (25 deg. Cent.). 


together and form a thin sheet on the glass. The temperature as in- 
dicated by the thermometer, at which the specimen begins to flow, 
is taken as the melting-point. 

Asphalts that cannot be ground are softened and pulled out to a 
thread and cut into small pieces, about 1 Several pieces 
should be placed on the glass together, as one will serve as a check on 
the other, and thereby lessen the chance of error. The softening- 
point may be noted by the rounding of the particles and the irelting- 
point by the beginning of the flow, or when the specimen begins 
to spread out (which is always at the point of contact with the glass), 
is set down as the temperature at which the specimens will melt. 

General Electric Method. This method is quite simple and 
consists of heating a quantity of the bitumen to be tested in a small 
can until liquid. The can containing the liquified bitumen is placed 
on a gram scale and balanced up. Then the scale is set 2 grams 
back and enough bitumen is taken out to rebalance the scale. The 
bitumen is to be removed by immersing the bulb of an ordinary 
Fahrenheit thermometer about 1J inches, or to about the 20-degree 
point. As the thermometer is dipped into the liquid it should be 
turned so as to get an even coating all over the surface covered. 
Then the thermometer should be held horizontally and turned 
constantly until the coating of bitumen is cooled. Next the ther- 
mometer is placed in a large test tube, which in turn is immersed 
in a beaker filled with glycerine. The beaker is then heated over a 
Bunsen burner at the rate of 7.2 deg. Fahr. (4 deg. Cent.) per minute. 
The test tube should have a small amount of glycerine placed in it. 
The thermometer is run through a cork large enough to support 
it \ inch above the glycerine. The temperature, as read directly 
on the thermometer, at which the bitumen drops and touches the 
glycerine is regarded as the melting-point. Fig. 92 shows the 
arrangement of the apparatus. 

Drop Point and Softening-point of Bituminous Compounds. The 
inventor of an apparatus for determining the drop-point test, Mr. 
II. W. Fisher,* says that his investigation showed: first, that a large 
majority of bituminous compounds, unlike minerals, have no well- 
defined melting-point ; that what some chemists specify as a melting- 
point is really a softening-point of the material; and third, that the 
melting-point as used by chemists corresponds to the temperature 
at which the compound will drop; hence, he believes that instead 
of using the misnomer " melting-point," it would be more practical 
to speak of the softening-point and drop point of compounds. 

* Proceedings of American Society for Testing Materials, Vol. 11, 1911, 



Fig. 93 gives a working drawing of an apparatus designed to put 
this idea into practice. For making the drop-point test, the com- 
pound in placed in hole 2, Fig. 93, A, hole 1 being the vent hole. 
Hole 2 can conveniently be filled by inverting the apparatus and 
letting the compound drip from a heated wire against which it is 
held. During this operation the vent hole should, of course, be 
filled with the rod /. The apparatus and rod are then cooled, 
after which the rod is removed. The surplus compound is removed 
so that its surface is flush with the bottom surface of the hole. 




FIG. 92. Apparatus for Finding the Melting-point of Bitumen by the " General 

Electric" Method. 

For making the softening-point test, the nipple shown in Fig. 
93, (d) is provided. A wrench for removing and inserting the nipple 
is shown at () The rod (/) is placed into the nipple through vent 
hole 4, after which both are heated above the melting-point of the 
compound. The compound hole 3 is then filled, and after partial 
solidification the rod is removed and the surplus compound cut off 
flush with the top of the nipple. Afterwards, the nipple is screwed 
into place as shown at Fig. 93 (c). 




Heating Coil 

For making the softening-point test and the drop-point test in one 
operation, the apparatus is filled with the compound, and a ther- 
mometer inserted as shown in Fig. 93 (c). The temperature i& 
increased at the rate of 7 deg. Fahr. (4 deg. Cent.) per minute until 
the compound comes up through the mercury. The temperature 
at which this occurs is called the softening-point of the the compound. 
Continuing the test further, the temperature at which a drop of the 
compound falls through the glass tube is called the drop point cf the 
compound. If the compound has a high softening-point and a high 
melting-point, a somewhat greater rise of temperature per minute 

is admissible to within about 30 
deg. Fahr. (16.6 deg. Cent.) of the 

Fig. 94 illustrates the method 
by which heat is applied unifcrirly 
over the entire apparatus. A fiter 
spool approximately 1^ inches 
inside diameter, 3 inches Icng, 
and 4 inches outside diameter, is 
wound with about 240 turns of 
No. 12 D.C.C. magnet wire. By 
means of alternating current of 60 
cycles, the iron testing apparatus 
is heated to any desired degree. 
The voltage employed varies 
between 30 and 55 volts, and the 
current from 4 to 8 amperes. For 
use with a direct current on a 110- 
volt circuit, wire of half the size 

should be used, and the voltage could be varied between 60 and 110 
volts. By either method the temperature can be kept almost con- 
stant at any degree or can be made to vary as desired. 

The testing apparatus and coil are placed on top of a large glass 
tube which is embedded in a wooden base. By means of a mirror 
at the side of the glass tube in the base, the melting of the compound 
in the drop-point test can be observed. When doing this, it is 
necessary to have an incandescent lamp on the opposite side of the 
base from the mirror. 

Flow Point of Bitumen. The flow-point test is mainly for com- 
parison of roofing pitches and asphalts. It is a method for obtaining 
the relative flow, or progressive tendency to glide, of one asphalt 
or pitch with another accepted as a standard, under the following 

FIG. 94. Electric Apparatus for 
Applying Heat Uniformly to the 
Apparatus for Determining the 
Drop Point and Softening-point 
of Bituminous Compounds. 


condition: On a corrugated strip of metal called a flow plate (Fig. 
95, A), 8 inches long and 2 inches to 4 inches wide, two pills of equal 
volume (made in a flow mold, Fig. 95, B), one of each material, 
are placed side by side but in separate grooves on one end of the 
plate. The plate is then placed in an air bath with the loaded end 
2J inches higher than the other. The whole is then placed in a water 
bath and heated to the boiling-point. This temperature is main- 
tained for an arbitrary period of time and then the glide of each 
material is measured. If the tested material is longer than the 
standard material, this indicates that it is softer; if the reverse 
obtains, that it is harder. 

As a practical test the flow point is quite serviceable in compar- 
ing the relative flow of roofing pitches and asphalts, but it is not 
serviceable and in fact is not used on waterproofing bitumens. It 



FIG. 95. Mold and Plate for Flow-point Test. 

bears no direct relation to either the melting-point or the penetration 
of the pitch or asphalt tested. 

Ductility Test on Bitumen. It is generally true that the greater 
the ductility of an asphalt, i.e., the extent to which it is capable of 
being drawn out in the form of a fine thread, the greater its cement- 
ing or cohesive value. The main function of the ductility test, 
however, is to reveal the possible amount of healing to be expected 
in a fractured bitumen in .the form of applied waterproofing. For 
a given penetration, the greater the ductility of an asphalt, the 
greater the healing or cohesive quality. Except when used for 
joint fillers and other special purposes, no asphalt should have a 
ductility less than 20 cm. at 77 deg. Fahr. (25 deg. Cent.). 

The test as made on the Abraham Tensometer* is shown in 
* Proceedings of American Society for Testing Materials, Vol. 10, 1910. 



FIG. 96. Abraham's Tensometer. 


Fig. 96. In this instrument the mold is the most vital part. In 
its new and improved form it consists of two cylindrical hardened 
steel sections (Fig. 97), resting together on circular knife edges and 
maintained in that position by three guide rods. The cross-section 
at the knife edges is exactly 1 sq. cm. The further ends of these 
two cup-like sections are threaded, and bear the outer caps which 
serve to fasten the mold in the instrument. 

After warming the mold, it is filled by unscrewing the upper cap, 
bringing the two sections firmly together and pouring in the melted 
bituminous substance, which assumes the form of a rivet, the smallest 
cross-section of which has an area of exactly 1 sq. cm. Then it is 

Note: All dimensions in 

FIG. 97. Details of Mold for Abraham's Tensometer. 

replaced in the machine and drawn apart until it breaks; the dis- 
tance thus traversed being recorded as the ductility of the specimen. 
Detailed information on this instrument may be found in the Pro- 
ceedings of the American Society for Testing Materials, Vols. 10 
and 11, 1910 and 1911. 

A simpler and more commonly used machine, the " Smith Duc- 
tility Machine," is shown in Fig. 98. The preliminary treatment 
of the bitumen and the preparation of the briquette for testing it 
with this machine are conducted as follows: The mold is placed 
upon a brass plate. To prevent the asphalt from adhering to the 
plate and the inner side of the two removable pieces of the mold, they 



are well amalgamated. The different pieces of the mold are held 
together in a clamp or by means of an India rubber band. 

The material to be tested is poured into the mold while in a 
molten state, a slight excess being added to allow for shrinkage on 
cooling. After the bitumen is nearly cooled, the briquette is 
smoothed off level by means of a heated palette knife. When 
cooled, the clamp is taken off and the two center pieces of the mold 
removed, leaving the briquette of asphalt firmly attached to the two 
ends of the mold, which serves as clips. The briquette is then 
immersed in water maintained at 77 deg. Fahr. (25 deg. Cent.), 

FIG. 98. The "Smith," Direct-connected, D.C. Electric Ductility Machine 

and Briquette Forms. 

for at least thirty minutes, or until the whole mass of bitumen is at 
that temperature. It is then placed in the machine and pulled 
apart as follows: The pointer is set at zero on the centimeter rule, 
and a thermometer is placed through a cork in the carriage, which 
will test the variation in the temperature of the water which may 
take place during the test. The distance registered by the pointer 
at the moment the thread of bitumen breaks gives the ductility, 
expressed in centimeters, of the sample under examination. 

Evaporation Test on Bitumen. In practice it is often necessary 
during waterproofing operations to keep pitch or asphalt for a long 
time in a molten condition at between 250 and 350 deg. Fahr. (121 
and 177 deg. Cent.). The pitch or asphalt which will volatilize 


off the least amount of oil and be the least changed in consistency 
by this heating is the most desirable. A heating test is therefore 
performed to determine the amount of loss of volatile oil during 
an arbitrary period of time. This, combined with the penetration 
of the residue left after such heating, is taken as a measure of the 
hardening effect to be expected, due to aging of the tar and bitumen 
materials. The reason for this is that evaporation and hardening 
go on continuously, though slowly, after the waterproofing is in 
place. To guard against rapid hardening and consequent brittleness 
of the bitumen, it is desirable to use an asphalt which will not lose 
more than 1 per cent and a pitch which will not lose more than 6 

FIG. 99. "Frea's" Electric Oven. (Chamber, 12 by 12 by 12 Inches.) 

per cent in weight when heated for five hours at 325 deg. Fahr. 
(163 deg. Cent.) in an electric oven, and not more than 3 per cent 
and 9 per cent respectively in a gas oven. After such heating, 
neither bitumen shall have its penetration reduced more than one- 
half the origind. The different amounts volatilized in each oven is 
due to the relative restricted circulation of air in the electric oven. 

This test* is usually made on 50 grams of bitumen which are 
weighed in a flat-bottomed dish, 2^ inches inside diameter, and If 
inch deep, placed in the oven and held exactly at 325 deg. Fahr. (163 
deg. Cent.) for five hours. Then it is cooled in a desiccator, and the 
loss in weight is noted. The electric oven shown in Fig. 99 is some- 

* Journal of Industrial and Engineering Chemistry, Vol. 3, No. 4, April, 1911. 



times used but gives lower results than the gas oven. Therefore 
specifications should state the type of oven to be used for the test. 

The gas oven shown in Fig. 100, which is still widely used, has 
the top and sides covered with 1.8-inch asbestos. The shelf is pro- 
vided with a J-inch asbestos pad, large enough to accommodate the 
dishes. The bulb of a Centigrade thermometer should be 1 inch 
above the shelf and the emergent stem should show the 90-degree 
mark. Not more than four tests must be run in the oven at a time. 



FIG. 100. Drying and Evaporating Gas Oven. 

1. Chamber, 8 by 8 by 12 inches, asbestos covered. 2. Dishes, 2 inches diameter, cen- 
trally located. 3. Thermometer. 

Determination of Free Carbon in Coal-tar Pitch. It has been 
stated that free carbon in pitch is an impurity from a chemical 
standpoint. This is not correct, as the so-called free carbon content 
in pitch is normally produced in the tar itself during the destructive 
distillation of bituminous coal in gas retorts or by-product coke 
ovens. This free carbon is present not as an impurity but as a product 
of the decomposition of hydrocarbon vapors during their travel 
along the heated walls of the retort or oven. It is a black, organic, 
powder held in suspension by the tar and probably consists, not only 


of free carbon, but also of hydrocarbons extremely rich in carbon. 
Actual analysis* show this free carbon to be composed of approxi- 
mately as follows: 

Carbon 89.85 

Hydrogen 3.30 

Nitrogen ..'...... 1 . 10 

Oxygen 3 . 13 (by difference) 

Sulphur 1.28 

Mineral ash 1 . 34 

The presence of more or less free carbon in tars is due to the heats 
at which the tar is produced and the size and shape of the retort, and 
the consequent relation between the quantity of vapors and surface 
of hot walls at which the vapors are exposed. Hence the production 
of free carbon is attended by the production of other characteristic 
hydrocarbon compounds, and the free carbon content of pitch is 
therefore, to a great extent, an index of the character of the hydro- 
carbon in the bitumen. In general, low temperature tars contain 
smaller amounts of free carbon and are characterized by the presence 
of large amounts of phenol bodies and sometimes paraffin com- 
pounds. The tars produced at higher temperatures containing 
more free carbon also contain large quantities of the characteristic 
aromatic hydrocarbons. Therefore, the belief that pitch can be 
made artificially to meet certain specifications, after introducing 
into an otherwise pure bitumen an adulterant of lamp black, or other 
carbon, cannot be substantiated, for such a mixture would violate 
the requirement of a straight-run pitch, and in the second place, 
while the result produced might contain the necessary amount of 
free carbon, it would not produce the characteristic bitumen accom- 
panying the normal free carbon content. 

Experience of years has even demonstrated that for certain 
purposes, and particularly for roofing and waterproofing work, 
pitch, fairly high in free carbon (containing between 20 and 30 per 
cent) is much more staple and less susceptible to temperature changes 
than pitches of low free carbon. 

The test to determine the free carbon content of bitumens or, 
as it is often alluded to, the hot toluol-benzol extraction test, is 
applicable to asphalts and coal-tar pitches, but is used especially 
in connection with the latter because other solvents, such as carbon 
bisulphide, are slower and more troublesome. The apparatus 

* Journal of Industrial and Engineering Chemistry, Vol. 6, No. 4, April, 1914. 
Adopted in slightly different form, in 1916, by the Am. Soc. for Testing Materials. 



for this test is shown in Fig. 101. The pitch is first dried, then it is 
passed through a 30-mesh sieve to remove any foreign substances. 
In testing materials of 5 per cent or more insoluble matter, 5 grams 
should be taken for the test. With lesser percentages, 10 grams 
should be used. The amount is weighed in a 100-c.c. beaker, and 
digested with about 50 c.c. of c.p. toluol on a steam bath for a period 
not to exceed thirty minutes. A filter cup, previously prepared, 
is weighed in the weighing bottle and placed in a carbon filter tube 
over a beaker or flask. The toluol-tar mixture is now decanted 
through the thimble and washed with hot c.p. toluol until cleaned, 


FIG. 101. Extraction Apparatus for Free Carbon. 

1. Flask. 2. Knorr extraction apparatus. 3. Copper wire. 4. Filter cup (2 sheets). 

using some form of " policeman," which is unaffected by toluol, 
for the purpose of detaching any residue which may adhere to the 
benker. The cup is finally given a washing with hot c.p. benzol 
and then after draining, is covered with a cap of filter paper or 
alundum, and placed in the extraction apparatus in which the c.p. 
benzol is used as solvent. The extraction is continued until the 
descending liquid is colorless. The thimble is then removed, the 
cap taken off, dried in the steam oven and weighed in the weighing 
bottle after cooling in the desiccator. For more detailed information 
regarding this test, the reader is referred to the " Journal of Indus- 


trial and Engineering Chemistry," Vol. 3, No. 4, April, 1911, and 
Vol. 6, No. 4, April, 1914. 

Ash Test. The ash test is not of great significance, and denotes 
whether there has been a mineral filler of any sort added to the 
pitch or bitumen. Normal coal-tar pitches will run between \ and 1 
per cent of ash, so that if extraneous matter is present, the ash 
may run above this amount. Refined asphalts, except Bermudez 
and Trinidad asphalt, run about \ of 1 per cent ash. 

The ash determination is made by burning to ash a 1-gram 
sample of the material in a weighed platinum crucible or dish of 
sufficient size. Heat is gently applied until the pitch or bitumen 
ignites, after which it is withdrawn. After the material ceases to 
burn, the heat is again applied until the residue is burnt free of 
carbon. The crucible and contents are then cooled and weighed 
and the ash determined. 

Fixed Carbon Test. Fixed carbon, as such, does not exist in 
any bituminous binder, but is the amount of coke produced by 
burning the bitumen in a certain specified and generally accepted 
manner. The test is frequently used in laboratories to aid in the 
classification of different bituminous materials, and in some instances 
is of value in helping to determine their probable origin. Aside from 
this, the test is of no value at all, as a means for determining the 
quality of the material, though it is also supposed to indicate the 
mechanical stability and substantial nature of the bitumen. There 
is, however, little or nothing in the fixed carbon test, either theo- 
retically or practically, which shows that a material containing over 
or under a certain definite percentage of fixed carbon is or is not 
suitable for waterproofing purposes. Because this is not a generally 
accepted view, it was deemed advisable to include a description of 
this test. 

The test is conducted as follows: One gram of the bituminous 
material is placed in a platinum weighing crucible between 20 and 30 
grams, between 28 and 38 mm. in height, and having a tightly fitting 
cover provided with a flange about 4 mm. in depth. The crucible and 
its contents are then heated, first, gently, and then more severely, 
until no smoke or flame issues between' the crucible and the lid. 
It is then placed in the full flame of a Bunsen burner for seven 
minutes, holding the cover down with the end of a pair of tongs 
until the most volatile products have been burnt off. The crucible 
is supported on a platinum triangle with the bottom 6 to 8 cm. 
above the top of the burner. The flame should be fully 20 cm. 
high when burning free, and the determination should be made in a 


place free from drafts. The upper surface of the cover shall burn 
clear, but the under surface may or may not be covered with carbon, 
depending on the character of the bituminous material. The 
crucible is removed to the desiccator, and, when cooled, shall be 
weighed, after which the cover shall be removed and the crucible 
placed in an inclined position over the Bunsen burner and ignited 
until nothing but ash remains. Any carbon deposited on the cover 
should also be burnt off. The weight of ash remaining should be 
deducted from the weight of the residue after the first ignition of 
the sample. The resulting weight is that of the fixed carbon, which 
should be calculated on the basis of the total weight of the sample, 
exclusive of mineral matter. 

.Paraffin Test. Paraffin is probably the best water-resisting 
material, but one of its adverse properties is lack of cohesiveness. 
Therefore its presence in a bitumen in more than moderate quantities 
would reduce the ductility of that bitumen and also its adhesiveness, 
or cementing value. Hence, it is sometimes desirable to determine 
the amount of paraffin present and to limit this amount depending 
upon the use to which the bitumen is to be put. But as all except 
paraffin petroleums (i.e., all semi-asphaltic and asphaltic petroleums) 
are known to contain less than 6 per cent, of paraffin it becomes 
unnecessary for practical use to determine the exact amount; first 
because this amount is not very injurious, and, secondly, the duc- 
tility test automatically precludes the possible presence of an excess 
quantity of paraffin in the asphalt. However, the subject is believed 
to need further investigation. The test for this material follows: 

One hundred grams of the bituminous material should be dis- 
tilled rapidly in a retort to a dry coke. Five grams of the distillate 
should then be thoroughly mixed in a 60-c.c. flask with 25 c.c. of 
Squibb's absolute ether. Twenty-five c.c. of Squibb's absolute 
alcohol should then be added, and the flask packed closely in a 
freezing mixture of finely crushed ice and salt for at least thirty 
minutes. The precipitate is then filtered out quickly with a suction 
pump using a No. 575 C. S. and S. 9-cm. hardened standard filter 
paper. The flask and precipitate are then rinsed and washed with a 
mixture of equal parts of Squibb's alcohol and ether, cooled to 
1 deg. Fahr. (17 deg. Cent.), until free from oil (50 c.c. of washing 
solution is usually sufficient). When sucked dry, the filter paper 
should be removed and the waxy precipitate transferred to a small 
glass disc and evaporated on a steam bath. The residue (paraffin) 
remaining on the disc is weighed, and from this weight the per- 
centage on the original 5-gram sample is calculated. 


Dimethyl Sulphate Test.* 'The dimethyl sulphate test is 
employed to detect the presence of petroleum or asphalt in coal tar. 
It is used either to determine the percentage mixture of asphalt with 
coal tar to meet certain specifications or to detect the presence of 
asphaltic products in coal tar as an adulterant. The test is mainly 
qualitative, but is valuable when even as little as 3 per cent of pe- 
troleum or asphalt products are present in the coal tar. 

The equipment necessary for the dimethyl sulphate test is the 
same as that specified for the distillation test recommended by the 
American Society for Testing Materials; Proc. 1911, Vol. 11, p. 240, 
and adopted in 1916. 

The pitch specimen is distilled and fractions taken at 518 to 572 
deg. Fahr. (270 to 300 deg. Cent.), 572 to 662 deg. Fahr. (300 to 350 
deg. Cent.), and 662 to 707 deg. Fahr. (350 to 375 deg. Cent.). These 
fractions are separately stirred and, if necessary, heated to dissolve 
solids which may be present. 

Four cubic centimeters of distillate from each fraction are sep- 
arately shaken with 6 c.c. of dimethyl sulphate ((CHa^SCU) in a 
10-c.c. cylinder. After standing thirty minutes the resultant super- 
natant layer of insoluble oil, from the petroleum or asphalt, is read 
and calculated to its percentage by volume of the sample of distillate 
taken. The results are reported as follows: 


Per Cent of 

Per Cent of Distillate 
Insoluble in Dimethyl . 







Many tests have been made to determine the permeability of 
cement mortars and concrete with and without admixtures of water- 
proofing materials. It is well to understand at least some of these. 
A brief description of the methods and the apparatus used and 
instructions on the performance of these tests will therefore be given. 
It is assumed that the reader is already acquainted with the physical 
properties and methods of testing the constituent materials of con- 
crete, and that he has a general knowledge of the manipulation of 
* U. S. Dept. of Agriculture. Bulletin No. 314, p. 25. 


apparatus for such tests. If this be not so, any standard book on 
concrete may be consulted with advantage. 

Standard Instructions for Permeability Tests. The following 
standard instructions for permeability tests on mortar waterproofed 
by the integral method have been used very successfully in the 
concrete testing laboratory of the Public Service Commission, First 
District, State of New York: 

" Mix the mortar in accordance with the directions accompanying 
the waterproofing compound which is to be tested. Make several 
specimens to be tested after seven days and several more to be 
tested after twenty-eight days. In no case make fewer than eight 
treated specimens (total number) and eight untreated specimens, 
for comparison. Use extra clean, coarse sand (not Ottawa sand) 
for these specimens in order that the waterproofing compound may 
receive no assistance from silt in the sand. 

" In the absence of different directions, mix the mortar to the 
same consistency as that of Ottawa sand mortar when mixed with 
60 per cent of water above what is required for normal consistency, 
e.g., if 10 per cent of water is required to make Ottawa sand mortar 
of normal consistency, then 16 per cent of water will be required to 
make Ottawa sand mortar of the desired consistency. Place the 
mortar in the 7J- or 8-inch pipe sections (see Fig. 102, A,) after it 
has been mixed hard with the hands for the time specified, or until 
a satisfactory mixture has been obtained. Specimens are then 
worked thoroughly into this mold with hands and trowel. Place a 
small amount in each mold and work it well to force out air bubbles 
before adding more mortar. Continue in this manner until the 
molds are full. The iron plates under the specimens must be 
thoroughly greased. Strike off the tops of specimens with a straight 

" Store the specimens in moist air twenty-four hours. Then 
brush both surfaces with a wire brush, mark, and place them in water 
until tested. Paint marks must not be placed on the surfaces which 
are to be tested. Specimens are not to be removed from the mold 
until after they have been tested. 

" Upon removing specimens from water for testing, brush both 
surfaces again with a wire brush. Test under a pressure of 50 
pounds per square inch for at least seven hours. If a measuring 
glass is used, some means must be found to prevent water from the 
outside from leaking into the measuring glass, since it has a tendency 
to follow down the outside of the outlet pipe. 

" Record results at fifteen-minute intervals. 


u On report show the time elapsed from application of pressure to 
first leakage, the average leakage for the time after specimen began to 
leak, and the maximum leakage for one hour. Express results in 
cubic centimeters per square foot per hour." 


FIG. 102. 

A. Permeability Molds and Test Pieces. 

B. Permeability Test Piece Holder. 

Description of Standard Apparatus. The apparatus* for holding 
the test pieces is shown in Fig. 102, B, in sections ready to assemble. 
Fig. 103 is a cross-sectional view of the test piece assembled ready 
for testing. A , A are rubber washers of 5-inch inside diameter and 
8-inch outside diameter; B, B are cast-iron top and bottom sections 

* Technologic Paper No. 3, U. S. Bureau of Standards, Dept. of Commerce 
and Labor, 



of the holder; C is the test piece 7J inches in diameter and 1, 2 or 3 
inches thick and is retained in corresponding short-length sections 
of 7^-inch diameter wrought-iron pipe; D is the retainer in which 
the water passing through the test piece is caught. 

The foregoing directions and apparatus have become most 
generally used in laboratory practice. Other methods are employed 
but the basic principles remain the same, that is, the measurement 
of the quantity of water that will come through mortar or concrete 
under a given static head of water. One of these methods used by 
Mr. Francis M. McCullough, B.S., in testing the permeability of 

FIG. 103. Cross-section of Apparatus for Holding Permeability Test Pieces. 

waterproofed concrete at the University of Wisconsin,* is exemplary 
and the following is a description. 

Method of Testing Permeability of Waterproofed Concrete. 
The apparatus used by Mr. McCullough for testing the permeability 
of concrete consists essentially of eight 6-inch pipes filled with con- 
crete and a pipe system connected with air and water reservoirs. 
Fig. 104, A, shows in detail the mold and attached casting and Fig. 
104, B, is a general drawing of the pipe system for four specimens, 
the apparatus for the remaining four specimens being the same as 

* Bulletin No. 336, University of Wisconsin. 


The molds are 6-inch wrought-iron pipe, 12 \ inches long, with 
a cast-iron flange screwed to the upper end. In order to prevent 
the passage of water between the pipe and the cement lining ten 
or twelve V-shaped grooves were cut in each pipe, each groove 
extending around the inner surface of the pipe. 

This flanged pipe was attached to the casting by means of six 
eyebolts. A f-inch pipe, 4 feet 6 inches long, was screwed into this 
casting. Each of these f-inch pipes was jointed to the main pipe, 
which, in turn, connected with the water main and with the air 
reservoirs. The shut-off globe valves for water and air are shown 
on the pipes connecting the main pipe with the water main and with 

Water Main Connected with University Supply 

Water Valve 


Pipe Connecting 
with Air Tank 

FIG. 104. 

A. Apparatus for Testing Permeability of Concrete. 

B. Section of Mold and Casting. 

the air reservoirs. The cast-iron cylinders, 6J inches in diameter and 
4 feet 8 inches long, formed the air reservoirs. They were connected 
with a large air tank, not shown, by means of the pipe shown in 
Fig. 104, B, a shut-off globe valve being placed between the air tank 
and air reservoirs. 

A glass tube and attached scale graduated to hundredths of a 
foot were fastened to each f-inch pipe in order to obtain the water 
level in the pipe. The globe valve V was used in order to dis- 
connect any specimen proving defective. The f-inch pipe and glass 
tube were drained by means of the needle valve. A gauge registered 
the air pressure. 


The specimens were securely bolted to the castings, a rubber 
gasket being used between the finished faces of flange and casting. 
With the air valve A closed and the air valve B opened, air was 
admitted to the reservoirs until sufficient pressure was obtained. 
The water valve was opened and water was allowed to fill the f-inch 
tubes. Care was taken that the pressure did not exceed that used in 
the test, this being regulated by opening the needle valves. Air 
valve B was closed and air valve A connecting with the air reser- 
voirs was opened, thus subjecting the specimens to pressure. 

The rate of flow of the water through the concrete was obtained 
by noting the scale readings and the time. Pressures were also 
noted, but they showed very little decrease as the volume of the 
air reservoirs was very large compared to the volume of the f-inch 
pipes. No readings were taken for five minutes after the pressure 
was on. As the rate of flow rapidly decreased readings were taken at 
intervals of ten or fifteen minutes for the first few hours and then at 
intervals gradually increasing from two to eight hours. The bottoms 
of the specimens were frequently examined and any dampness noted. 

When readings are taken all joints should be carefully examined 
and any leaks noted, and the effect of this leakage eliminated as much 
as possible in reducing the data. 

The proportions by volume of the concrete were 1:3:5, the 
required amount of materials being weighed. No attempt was made 
to secure a waterproof concrete by proper proportioning. On the 
contrary, a lean mixture was desirable in order to bring out the water- 
proofing qualities of the compounds. Local stone and sand and 
Portland cement were used. The stone was a rather sandy lime- 
stone, while the sand was of the fine .bank variety. 

Results of Permeability Tests on Waterproofed Concrete. We 
will now consider the results of these tests on concrete treated with 
a few waterproofing compounds. These compounds may be classi- 
fied according to the manner in which they were used in the tests. 

(1) Compounds applied to the surface of the concrete, which in 
themselves may be sub-divided into three classes : 

(a) Compounds which are applied as surface paints. 

(b) Compounds which were applied in layers to form a 


(c) Compounds which were applied as a surface coating in the 

form of a thick layer. 

(2) Foreign ingredients added to the body of the concrete. 

(3) Foreign ingredients added to the mortar coating. 

(4) Plain cement mortar. 


Different methods, as illustrated in Fig. 105, were used in 
finishing the upper surface of the specimens, depending upon the kind 
of waterproofing compound used. As shown in Fig. 105, A and B, 
the concrete was finished flush with the top of the pipe, the upper 
surface of the concrete being well troweled. Before troweling, the 
specimens were allowed to stand a half hour in order that the free 
water on the concrete might be absorbed. The cement lining extends 
to the top of the concrete in B, while in A it is cut off \ inch below. 
In the specimens that were coated with mortar, as shown in Fig. 105, 
C and D, the surface of the concrete was f inch below the top of the 

Waterproofing Material 


Mortar Coating for 

Mortar Coating for 

C D 

FIG. 105. Methods of Finishing Upper Surface of Concrete Specimens. 

pipe. After the concrete had absorbed the standing water the 
mortar top was added, the surface of the concrete and the mortar 
being thoroughly troweled. In applying all surface preparations, 
care was taken to secure a dry, clean surface and to have the prep- 
aration well brushed in. The water pressure varied from 20 
pounds to 40 pounds per square inch applied continuously from 
three to seven days. 

In all cases except those in which the compounds were applied 
in the form of a membrane, the results were variable. The materials 
used were more or less reliable but the results obtained were not 
often enough satisfactory to establish a single superior compound. 


In most cases where a material withstood the low pressure it failed 
completely under the higher pressure. None withstood either 
pressure absolutely without absorption or percolation, with the 

^ Bolt* 


-U< Tubing 

,%"</> BolU 


On No. 8-12 


FIG. 106. Types of Permeability Specimens. 

one exception noted above. Similar tests made on f-inch plain 
cement mortar of proportions 1 : 1J applied to the concrete (Fig. 
105, C), proved two facts: (1) that plain mortar can be made rea- 


sonably watertight; (2) that some of the above compounds, such 
as the foreign ingredients added to the mortar coating, are also 
reasonably effective and warrant their use under certain conditions. 
Results of Permeability Tests on Plain Concrete. Still another 
method for testing the permeability of mortar and concrete, though 
only occasionally used, is worth noting. In an elaborate series of 
permeability tests,* in which machine-mixed concrete and large 
specimens having a prescribed volume of concrete were used without 

FIG. 107. Longitudinal Sections of "PU" and "PUHC" Permeability Specimens. 

any waterproofing added to them, many valuable facts are made 
patent. The forms of specimens are shown in Figs. 106 and 107. 
In molding these test pieces, both mortar shell and concrete core 
were cast at the same time. The area of the core is 1 square foot, 
hence the leakages read were in terms of this unit. 

The results of these permeability tests, made on 294 gravel- 
concrete specimens, agree very well with similar tests made by 
other experimenters. Of the above number 88 were of 1 : 1^ : 3 
and 67 of 1:2:4 proportions by volume; 98 were of 1:3:9 
proportions by weight. 

* Journal of the Western Society of Engineers, November, 1914, Vol. 19, No. 9. 


None of the coricretes tested was absolutely watertight if we 
consider continuous flow into the specimen as proof of permeability, 
but the majority of mixes were so impervious that no visible evidence 
of flow appeared. For most purposes such mixes can be considered 

The visibility of dampness on the bottom of the specimens 
increased with the humidity of the air and the non-homogeneity of 
the concrete. The minimum rate of flow for which leakage was indi- 
cated was 0.00011 gallon (approximately .42 c.c.) per square foot 
per hour. 

In tests of nearly all of the properly made mixes of 1 : 2| : 4J 
proportions, or richer, the rate of flow for a fifty-hour period was less 
than 0.0001 gallon (approximately .38 c.c.) per square foot per hour 
under a pressure of 40 pounds per square inch. 

Through increasing the fineness of the cement a reduction in 
the rate of flow and a considerable increase in the strength of a 
1:3:6 mix were secured. 

By grading the sand and gravel in accordance with Fuller's 
curve it was possible to obtain practically watertight concrete of 
1:3:6 proportions under pressures less than 40 pounds per square 
inch. To secure such results, however, requires great care and 
careful supervision in mixing, in determining the proper consistency, 
in placing, and in curing the concrete. 

In the proportioning of such materials as these, volumetric 
analysis coupled with a determination of the density and air voids 
yields very valuable information concerning the best proportions of 
sand and gravel for a given proportion of cement. If proportions 
must be selected arbitrarily, a 1 : 1J : 3 mix, by volume, is very 
impervious. It should be remembered, however, that the volume 
changes in rich mixtures due to alternate wetting and drying are 
much greater than for lean mixtures. Consequently due attention 
must be given to the provision of expansion joints and reinforce- 
ment in structures made of rich mixtures. 

The use of the proper amount of water necessary to produce 
a medium or mushy consistency is one of the most important con- 
ditions in securing impervious concrete, especially when lean mix- 
tures are used. Dry mixtures cannot be sufficiently compacted in 
the molds and are more difficult to cure properly than the mushy 
mixtures. Although the use of a wet consistency does not materially 
affect the imperviousness of very rich mixes, such as 1 : 1J : 3, it 
greatly increases the flow through a lean mix. 

For lean mixes made from damp sand, it seems advisable to mix 



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of a cement floor are almost directly proportional to the amount of 
troweling work put upon it without crazing the surface. 

From a study of numerous applications, of mineral, metal, and 
liquid floor hardeners, and a review of Table X, the liquids, in 
general, seem to give much better service, being also more easily 
applied, and when wear develops, may be as easily reapplied. 

The abrasion tests,* results of which are given in Table X, 
were made on an abrasion apparatus consisting of a 16-inch cast- 
iron disc, revolving at the rate of 42 revolutions per minute. Fine 
sand was fed upon this disc by means of two funnels each placed 
6 inches from the center of the disc. The size of the opening at 
the bottom of each funnel was regulated by means of a metal slide. 
The sand used was fine beach sand graded so that all particles 
passed a No. 50 sieve and were retained on a No. 100 sieve. Two 
test samples placed opposite each other, were held down upon this 
disc by being placed in weighted cylindrical holders. This machine 
was so devised that these holders could hold the center of the speci- 
mens always on the circumference of a 12-inch circle. 

Mortar cylinders 2 inches in diameter and 1| inches high were 
used as test samples. A good grade of Portland cement and Long 
Island bank sand were used throughout. No attempt was made to 
surface a sample with a thin coating of any compound. Wherever 
specific directions were furnished with a compound, these directions 
were closely adhered to. Eight cylinders were made with each 
batch of mortar to be tested, four cylinders containing the com- 
pound to be tested and the remaining four were of plain mortar. 
Two treated and two untreated specimens were tested at seven 
days and the remaining specimens were tested at twenty-eight days. 

All specimens were dried until they showed no further loss in 
weight. The specimens were then carefully weighed and calipered. 
Measurements were taken by micrometer calipers at five points 
the center and at four points equally distant on the circumference. 
The cylinders were ground in groups of two one plain and one 
treated specimen for thirty minutes. Approximately 450 grams 
of sand were used in each test. The samples were then again 
weighed and calipered. In determining the loss in thickness of each 
cylinder, the cylinder was considered as being composed of four 
triangles, the center being the common vertex. For this reason, 
the center measurement was given a weight of four and each mea- 
surement on the circumference given a weight of two. 

* Tests made in Physical Laboratory of the Public Service Commission, 1st 
Dist., New York, 1917. 


The results noted in the table are undoubtedly representative of 
average 1:2:4 concrete. 

The most interesting fact disclosed is that the absorption of con- 
crete is very little affected by the greater or less absorptiveness of 
the various large aggregates except cinders (see Table I). In other 
words the absorption of concrete is dependent mainly on the matrix. 


Concrete floor hardeners are applied to floors for the purpose of 
making them dustproof and waterproof by surface densification. 
The term " floor hardener " is a misnomer, as most of the materials 
used, with the exception of carborundum and like materials, do not 
add to the hardness of the floor, but give merely a better wearing 
floor due to other properties than hardening properties. Abrasive 
tests described below on these materials conclusively prove the fact 
that they do not add hardness to a cement floor. However, these 
materials are not confined to minerals or metals only, but may be 
liquids, with bases of wax, oil, varnish, etc., these generally being 
applied to the finished floor. The mineral or metal materials are 
sometimes incorporated in the concrete or cement mortar before 
these have finally set, but in most instances, they are merely dusted 
on the surface and troweled in. This gives a floor surface with a 
more or less thin layer which may wear through, leaving the floor 
practically in the same condition as an untreated cement floor. 
The effect of the more successful floor hardeners is to produce a 
floor really more dust proof, due to the smooth surface of the finished 
floor. This naturally implies a floor with a minimum of surface 
voids and crevices to hold dust and moisture, and also little liability 
to raveling. However, when a hard material like carborundum 
is used, a hard floor and not a smooth floor is obtained. This type of 
floor presents a rough, coarse surface, and is in fact a very dusty one. 
From the point of view of floor hardeners, the best dustproof floor 
is a terrazzo floor (mainly used in public buildings), in which the 
wearing surface is largely the coarse aggregate used in the floor. 
This is ground by hand or by machine to present a maximum wear- 
ing surface and reduce the mortar of the wearing surface to a 

The efficiency of some of the floor hardeners is often less due to 
the character of the hardener than to the extra work required in 
troweling the treated floor. In fact, the smoothness and hardness 



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of a cement floor are almost directly proportional to the amount of 
troweling work put upon it without crazing the surface. 

From a study of numerous applications, of mineral, metal, and 
liquid floor hardeners, and a review of Table X, the liquids, in 
general, seem to give much better service, being also more easily 
applied, and when wear develops, may be as easily reapplied. 

The abrasion tests,* results of which are given in Table X, 
were made on an abrasion apparatus consisting of a 16-inch cast- 
iron disc, revolving at the rate of 42 revolutions per minute. Fine 
sand was fed upon this disc by means of two funnels each placed 
6 inches from the center of the disc. The size of the opening at 
the bottom of each funnel was regulated by means of a metal slide. 
The sand used was fine beach sand graded so that all particles 
passed a No. 50 sieve and were retained on a No. 100 sieve. Two 
test samples placed opposite each other, were held down upon this 
disc by being placed in weighted cylindrical holders. This machine 
was so devised that these holders could hold the center of the speci- 
mens always on the circumference of a 12-inch circle. 

Mortar cylinders 2 inches in diameter and 1J inches high were 
used as test samples. A good grade of Portland cement and Long 
Island bank sand were used throughout. No attempt was made to 
surface a sample with a thin coating of any compound. Wherever 
specific directions were furnished with a compound, these directions 
were closely adhered to. Eight cylinders were made with each 
batch of mortar to be tested, four cylinders containing the com- 
pound to be tested and the remaining four were of plain mortar. 
Two treated and two untreated, specimens were tested at seven 
days and the remaining specimens were tested at twenty-eight days. 

All specimens were dried until they showed no further loss in 
weight. The specimens were then carefully weighed and calipered. 
Measurements were taken by micrometer calipers at five points 
the center and at four points equally distant on the circumference. 
The cylinders were ground in groups of two one plain and one 
treated specimen for thirty minutes. Approximately 450 grams 
of sand were used in each test. The samples were then again 
weighed and calipered. In determining the loss in thickness of each 
cylinder, the cylinder was considered as being composed of four 
triangles, the center being (he common vertex. For this reason, 
the center measurement was given a weight of four and each mea- 
surement on the circumference given a weight of two. 

* Tests made in Physical Laboratory of the Public Service Commission, 1st 
Dist., New York, 1917. 


From a detailed review of Table X the following facts are 
noted: Iron filings injure the wearing qualities of a concrete floor. 
Iron filings treated with salammoniac cause a mortar to fail 
completely. These results, however, are not regarded as conclusive. 

A 4 per cent solution of calcium chloride will rapidly increase 
the hardness and tensile strength of a mortar during the first seven 
days. This advantage however is overcome after twenty-eight days. 

Carborundum greatly increases the hardness of a floor. Very 
little wear occurs after the top skin of cement has been ground off. 

A coarse sand aggregate or an aggregate of sand and grits gives a 
more wear-resistant mortar than that made of finer sand. 

Comparison of Melting-points of Bitumens.* Ten samples of 
asphalt were tested according to the requirements of each of the 
first three of the following standard methods for finding the melting- 
point of bituminous material and twenty samples according to the 
fourth method (but not tabulated below). 

(1) C. I. Robinson, or the Ring and Ball Method. (R. and B. 

(2) Cube-in-water Method (C.-in-W. Method). 

(3) Kraemer and Sarnow Method (K. and S. Method). 

(4) Mabery-Sieplein Method (M.-S. Method). 

A careful perusal of the description of these methods, given on 
page 197 will facilitate understanding the purpose and results of this 
test, especially because of lack of uniformity of opinion by chemists 
as to preference, superiority or correctness of any of them. 

From the values in Table XI it is evident that the Cube-in-water 
Method registers a comparatively high melting-point and cannot 
be altogether reliable for the reason that the specific gravity of the 
bitumen enters as a factor in these figures. It is also evident that 
the Ring and Ball and Kraemer and Sarnow Methods are probably 
more correct, because of close agreement of the results and because 
these are independent of the specific gravity of the bitumen. 

A similar but more extended series of tests f was made on various 
asphalts and pitches, to determine the conversion factors between 

* This and the following eighteen tests are reprinted from a paper by the 
author in the N. Y. Municipal Engineers' Journal, Vol. 3, No. 7, September, 1917. 
Attention is directed here to the fact that the following tests are far from being 
exhaustive or complete either in technique or interpretation of results. But 
partly for the reason explained in the forepart of this chapter and partly because 
of their suggestive value it was considered warrentable to reprint them here. 

f These tests were made in the Chemical Laboratory of the Public Service 
Commission for the First District, State of N. Y.; R. L. Oberholser, Chief 



the four methods. From the results thus obtained, and the tabu- 
lated values given above, Table XII was constructed. By means 
of this table the known melting point of a bitumen by one method 
is readily converted to an equivalent value by another method. 




and Cube-in 


Water and 
Kraemer and 

Kraemer and 




























6. . 


























Method Given Values 
in Degrees Fahrenheit. 



and Sarnow 




Add 5 

Add 25 
Add 35 

Subtract 20 
Subtract 25 

Subtract 30 
Subtract 35 
Subtract 15 

Kraemer and Sarnow . . 

Subtract 5 
Add 20 
Add 30 


Effect of Heat on Various Pitches Mixed with Linseed Oil.* A 
mixture of pitch and linseed oil is often used as a pipe-coating, 
and as a coating for steel and cast-iron tunnel segments. In applying 
this compound, it is found necessary to heat it in open tanks IGI very 
long periods. Hence, the question: what effect has such heating 
upon the mixture? To learn the answer to this question, a seventy- 
two hour heating test was made with three grades of pitch, the 
results of which are given in Table XIII. 

* Test made in Chemical Laboratory of Public Service Commission for 
the First District, State of N. Y.; R. F. Oberholser, Chief Chemist. 
















Kind of Pitch. 




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Straight-run coal-tar pitch and raw linseed oil of good quality 
were used in this test. The melting-point was determined by the 
Cube-in- water Method. 

This test discloses the fact that prolonged heating of pitch even 
when mixed with linseed oil, is injurious, as shown by the amount 
of oil evaporated, and the great rise in melting-point. 

Hence it is imperative not to subject this coating material to 
continuous heat, but if this becomes unavoidable, the tank must be 
frequently replenished with new material. 


Flowing and Bonding Properties of Pitch Containing Small 
Quantities of Asphalt or Linseed Oil. To obviate the danger and 
nuisance of using hot coal-tar pitch for waterproofing by the mem- 
brane method under compressed air, tests were made to determine 
the flowing and bonding properties of different melting-point pitches 
mixed with either 5 per cent of raw linseed oil or 5 per cent of dif- 
ferent melting-point asphalts. These additions were made in an 
effort to increase the fluidity of the pitch somewhat without reducing 
its " substantiality " and to avoid the necessity of heating it on 
the work during application. These additions had the desirable 
effect of lowering the melting-point of the pitch about 10 deg. Fahr. 
(5.5 deg. Cent.) without increasing its hardness. 

Four pitches were tested having the following melting-points: 
75, 85, 95 and 105 deg. Fahr. (24, 29.5, 35 and 40.5 deg. Cent, respec- 
tively). (Cube-in-water Method.) 

The three asphalts used to make the 5 per cent additions had the 
following melting-points: 107, 154 and 182 deg. Fahr. (42, 68 and 
83 deg. Cent.). (Cube-in-water Method.) 

The oil used was a good quality raw linseed oil. 

Sixteen samples of pitch were weighed out in pint cans and 
each set of four of equal melting-point received an addition of 5 per 
cent by weight of one of the three different asphalts or the oil. These 
were then heated,' thoroughly stirred, and allowed to cool to about 
75 deg. Fahr. (24 deg. Cent.) which was approximately the tem- 
perature of the compressed air chamber under about 21 pounds 
pressure. On reaching this temperature each sample was troweled 
onto the surface of pieces of treated fabric until a 3-ply membrane 
was built up on planed boards as a ground work. None of the 
pitches was fluid enough to be mopped on, hence the troweling. 
The boards were then inclined at an angle of 45 degrees for seventy- 
two hours to compare the relative amount of sliding of each mem- 
brane. Table XIV shows the results obtained from the various mixes. 

Specimens Nos. 2 and 5 appear to be best suited for the purpose, 
because at the temperature under which they will be used, they are 
both more substantial and v/orkable than the others. Finally, 
since the admixture of linseed oil greatly increases the cost of the 
product, the one (No. 5) with an admixture of asphalt is to be pre- 

Effect of Asbestos Filler on the Physical Properties of Bitumen.* 
The purpose of this test was to determine whether any real benefit 

* Test made in Chemical Laboratory of the Public Service Commission for the 
First District, State of New York, R. L T Oberholser, Chief Chemist. 



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accrues to waterproofing asphalt by the incorporation of asbestos 
of the shredded or fibrous variety, as was the practice on some of 
the subway work in New York City. 

In preparing the specimens the bitumen was heated until liquefied 
and the various amounts of asbestos added and stirred until the 
mixture was a homogeneous mass. Table XV shows the results 
of the test. 





at 32 

at 62 

at 77 

and Sarnow 




























The most evident conclusions from this test are, that due to the 
presence of the asbestos the ductility of the bitumen is considerably 
decreased and the melting-point is increased. The former fact 
indicates that the mixed bitumen would not hold together in the form 
of a thin coating as well as the pure bitumen, while the latter indicates 
that the mixed bitumen would flow with greater diffculty than the 
pure bitumen at the same temperature. 

Ductility of Asphalt Containing Coal-tar Pitch. The purpose of 
this test is to determine the effect on the ductility of asphalt of the 
addition of coal-tar pitch in various percentages. Both the asphalt 
and the pitch were of the grade regularly used in waterproofing the 
dual subways in New York. 

The melting-point of the pitch was about 116 deg. Fahr. (47 deg. 
Cent.) by the cube-in-water method, and the asphalt about 120 
deg. Fahr. (49 deg. Cent.) by the Kraemer and Sarnow method. 


Starting with the pure asphalt in a molten condition the mix- 
tures were made by adding the pitch in increments of 5 per cent by 
weight. The specimens were then tested and gave the following 
results: The melting-points of the mixtures showed a decided but 
not constant increase with increase of pitch. The penetration of 
the mixtures showed an almost constant decrease and at propor- 
tions between 25 and 40 per cent of asphalt the penetration 
approached zero. The addition of 30 to 40 per cent of pitch to the 
asphalt reduced the ductility of the mixture to zero, while even as 
little as 5 per cent reduced the asphalt's ductility from more than 
100 to 30 or 40 cm. It seems, therefore, inadvisable to mix coal- 
tar pitch and asphalt when this is intended for waterproofing by the 
membrane system. It may, though, be good as a waterproof or 
dampproof surface coating on masonry suited for its application, 
or as a roof flashing compound. A waterproofing membrane must 
be elastic and ductile to a reasonable degree to avoid cracking in 
conjunction with the structure it surrounds. Mixing these two 
materials tends to vitiate this by giving the product the property of 
" shortness," or lack of ductility. 

It should be remembered, however, that inferior grades of 
pitch might even have a deleterious effect on the asphalt or 
vice versa. 

Effect of Temperature on Penetration and Ductility of Asphalt 
and Coal-tar Pitch. The penetration and ductilities noted in these 
tests were made with the Dow penetrometer and tensometer, both 
standard testing machines used in asphalt laboratories. 

Fig. 108, which is quite self-explanatory, shows that according 
to penetration the coal-tar pitch, though of lower melting-point, 
and tested in both pure and mastic forms, is harder at low tem- 
peratures and softer at high temperatures than the asphalt; also 
that the asphalt has a wider temperature range, that is, the asphalt 
is less affected for a given temperature change and softens more 
slowly than coal-tar pitch. 

The curves in Figs. 109 and 110 show the relative penetration 
and ductility of asphalt and coal-tar pitch whose melting-points 
are practically equal, as determined by the Kraemer and Sarnow 

From a study of the penetration curves the following facts may 
be noted: 

(1) The asphalt and its mastics are softer than coal-tar pitch 
between the approximate limits of 40 and 90 deg. Fahr. (4.5 and 
32 deg. Cent.). 





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(2) The coal-tar pitch curves show that the pitch is more affected 
by change of temperature than the asphalt. This is not quite 
obvious, however, unless we assume a common point for both curves, 
which would very likely be near the melting-point of both materials. 
Then, if measured from this point, the above fact is readily proved. 

(3) Of both pitch and asphalt mastics the pitch mastic of pro- 
portions 2 : 2 : 1 is more affected by temperature changes. 

(4) Of the asphalt mastics, the one of proportions 1:1:1 is 
least affected by temperature changes. 

Melting Points (K.& S.Method) 
Asphalt 126 F. 

Coal-tar Pitch 103 F. 



60 70 

Temperature, Deg. Fahr. 

FIG. 108. Relation of Penetration to Temperature of Asphalt and Coal-tar 
Pitch; also Asphalt and Coal-tar Pitch Mastic, Mixed in the Proportions 
of 1 Part Bitumen, 1 Part Sand, and 1 Part Limestone Dust. (Points of 
Curves are the Means of three Sets of Readings on Penetration Machine 
Using a No. 2 Cambric Needle, Weighted to 100 Grams and Acting for 
Five Seconds.) 

The following conclusions are noted from a study of the ductility 
curves : 

(a) Asphalt and its mastics are more ductile than coal-tar pitch 
(both of the same melting-point), but its rate of change of ductility 
is less, hence it is less affected by temperature changes. 

(6) For work exposed to great temperature changes the asphalt 
is to be preferred to coal-tar pitch. For work not exposed to great 
temperature changes coal-tar pitch is to be preferred on account of 
its greater chemical stability. 





Comparative Tests on Coal-tar and Asphalt Mastics.* Here- 
tofore asphalt alone Has been used for making mastic for brick-in- 
mastic usually used for waterproofing underground structures. The 
purpose of these tests was to ascertain the adaptability of straight- 
run coal-tar pitch for making mastic for the same purpose. 

The tests were made to cover the requisite properties of a mastic 
for waterproofing by this method, these properties being as follows: 

(1) The mastic must have a small and limited compressibility 
at a temperature between 32 deg. Fahr. (0 deg. Cent.) and 77 deg. 
Fahr. (25 deg. Cent.) 

(2) It must be flexible or pliable, that is, it must be able to bend 
on itself without fracture at 40 deg. Fahr. (4.5 deg. Cent.) or less. 

(3) It must be adhesive and cohesive enough to heal at 40 deg. 
Fahr. or less. 

(4) It must be tough enough at 32 deg. Fahr. to resist cracking 
due to impact and vibration caused by moving loads. 

(5) It must be reasonably ductile at temperatures between 32 
deg. Fahr. and 77 deg. Fahr. 

(6) It must be of uniform consistency however proportioned. 

(7) The extracted bitumen must have very little (not more than 
3 per cent) volatile oil. 

(8) The mineral aggregate must pass 100 per cent through a 
10-mesh sieve. 

Two kinds of coal-tar pitch and one of asphalt were used in 
making the test specimens. One pitch was a straight-run product 
meeting the specifications given on page 281; the other was also a 
straight-run product brought down to the same penetration as the 
asphalt under test. The asphalt was a refined Mexican oil made 
to meet the specifications given on page 282. 

Two sets of tests were made. In one, the ingredients were pro- 
portioned by weight one sand, one limestone dust or cement, 
four bitumen. In the other, the ingredients were proportioned 
by volume one sand, one limestone dust or cement, two bitumen. 

The reason for making two sets of tests, one with about twice as 
much bitumen as the other, was to ascertain the relative effect on 
the properties of the mastic by the presence of more or less 

Since in the past asphalt mastic has been used exclusively in the 
brick-in-mastic system of waterproofing, and since there is no 
reported failure of this method or material, it was accepted as the 

Test made under supervision of author in the Research Laboratory of the 
Barrett Company, in 1915. 


standard, i.e., all results were compared to the results obtained on 
the asphalt mastic. These values, given in Table XVI, were averaged 
and the following conclusions are drawn from a study of this 

(1) A limited amount of compressibility being both useful and 
necessary in a bituminous mastic, this property shows up generally 
in favor of the hard-pitch mastic. 

(2) Penetration a measure of the hardness of the mastic, 
but not a very reliable test, owing to the presence of sand particles 
is generally in favor of the hard-pitch mastic. 

(3) The bending test, showing the temperature at which fracture 
will occur, shows in favor of the soft-pitch mastic ; this may be bent 
at about 140 deg. Fahr. (60 deg. Cent.) lower than the hard-pitch 

(4) The healing test, probably the most important, indicating 
the inherent capacity of the mastic to restore itself after cracking, 
shows in favor of both pitch mastics. 

(5) The impact test, indicating the resiliency of the mastics, 
a property important for the conditions under which the material 
is usually used, shows in favor of the soft-pitch mastic. 

(6) The ductility test, indicating the tenacity of the material, 
shows in favor of the soft-pitch mastic. 

(7) The gas-drip test, indicating the capacity of the material to 
resist the deteriorating effect of gas-polluted earth, shows in favor 
of both the pitch mastics. This resistance is mainly due to the 
presence of the free carbon in the pitches, but is obviously not a 
governing property. 

From the foregoing it is evident that both pitches are better 
in some of the desirable properties than the asphalt, but neither 
excels in all the requisite properties. But by interpolating the results 
given in the table, a grade of coal-tar pitch was evolved, meeting 
the specifications for brick-in-mastic waterproofing given in Chapter 
VIII, and this may be used under the same conditions where the 
asphalt mastic is used. 

Volume Reduction of Asphalt Mastics. In the mastic and water- 
proofing industries it is a matter of common knowledge that the 
volume of the finished mastic is not equal to the total volume of its 
ingredients, just as in the case of concrete. The loss in volume was 
assumed to be anywhere between 5 and 20 per cent. The follow- 
ing test was therefore made to determine this value with closer 
approximation : 

Equal volumes of asphalt, sand and cement were mixed in a 


fire-heated kettle until a satisfactory mastic was formed. The volume 
was then measured and found to be approximately 30 per cent less 
than the total volume of ingredients. 

Another mastic was then made with equal volumes of asphalt 
and mineral aggregate; the latter composed of one part cement and 
three parts sand. This mixture showed about 20 per cent loss in 
volume. Other mixtures were made and showed losses between these 
limits depending on the proportions of sand and cement in the mineral 
aggregate, and the length of time the mastic was stirred. This 
established the fact that 20 per cent and not 5 per cent is the mini- 
mum, and about 30 per cent the maximum reduction of volume for 
mastic used with bricks to form what is known as the brick-in- 
mastic waterproofing envelope. But even these figures are materi- 
ally affected by the duration of the mixing process, the volume 
further decreasing with prolonged stirring. 

Mastic Bond Affected by Surface Condition of Bricks. In an 
effort to determine the relative bonding power of waterproofing 
mastic on bricks in various conditions, the following test was made: 

Five bricks were embedded in a 50 per cent asphalt mastic, that 
is, a mastic composed of fifty parts asphalt and fifty parts mineral 
matter. The first brick embedded was dry and clean; this was 
followed by a moist brick, then by a wet brick, then by two bricks 
somewhat blackened with soot, as would be the case if the bricks 
were dry heated over an open wood fire, as is often done. When the 
mastic cooled and hardened the bricks were pulled up and showed 
the following: 

(1) The dry and clean brick could not be extracted from the 
mastic intact. 

(2) The moist brick showed but little bond and was easily 

(3) The wet brick showed no bond at all. 

(4) The soot-blackened bricks showed fairly good bond, enough 
to demonstrate that a thin coat of soot is not objectionable in brick- 
and-mastic work. 

Relative Compression of Plain Brick, Brick and Mortar and Brick- 
in-mastic. The brick-in-mastic specimens were made in accord- 
ance with prevailing practice, that is, two bricks were laid in mastic, 
side by side, on their largest bed, as stretchers. But for testing, the 
specimens were not incased in concrete, as is usually done in prac- 
tice. The specimens were four bricks high, with a minimum of 
|-inch joints and each completely covered with asphalt mastic. The 
proportions of the mastic ingredients were about 40 per cent asphalt, 



30 per cent sand and 30 per cent cement, by weight. The bricks 
were the ordinary building variety, 2J by 3f by 8 inches. 

The joints of the wooden form used for making the specimens 
were purposely made not absolutely tight, as this is a condition which 
occasionally occurs in practice. As a result, some of the hot mastic 
leaked out, leaving a considerable void between two bricks above 
the level of the leak. 

One of the forms was also made somewhat narrow, that is, its 
width did not permit more than about a -j^-inch joint. The result 
was that on inserting the brick the mastic was squeezed out between 
the form-side and brick. The latter was in consequence only partly 
covered with mastic. 

These conditions illustrate the necessity of making tight-joint 
forms and also wide enough to allow sufficient mastic between all 
brick faces. 

Three specimens were made as above noted (in good forms) and 
when tested for compression at about 70 deg. Fahr. (21 deg. Cent.), 
gave the results noted in Table XVII, to which, also, are added for 
comparison, the ultimate compressive strength of plain brick and 
brick and mortar. 


(Lb. per Square Inch) 

Brick and Mastic. 

Brick and Mortar.* 

Plain Bricks.f 





2440 (a) 





*Compression on column./S X8 inch base, 1 foot 4 inches high, of common brick and mortar, 
(a) Lime mortar, 1 : 3 proportion; (6) Portland cement mortar, 1 : 2 proportion, 
t Compression on largest bed of single bricks. 

On all three tests of the brick-in-mastic, the bricks failed first. 
The reason for this is that the mastic, when compressed, tends to 
spread and actually does so, and however slight this may be, it 
places the brick under a transverse tension, consequently reducing 
its compressive strength, as indicated in the table above. However, 
it should be borne in mind that the compressive strength of brick- 
in-mastic would be increased considerably, perhaps quadrupled, 
by being encased in concrete, as it actually is in practice. The 
temperature of the brick-in-mastic will also have a marked effect 


upon its strength. A continued, comparatively low temperature, 
however, will not prevent the ultimate destruction of the bricks by 
transverse tension, but only retard it, unless, of course, the brick- 
in-mastic is well encased in masonry to prevent it. 

Effect of Temperature of Saturants on Waterproofing Fabrics. 
The purpose of this test was to determine (1) the effect of high tem- 
peratures on waterproofing felt and fabrics while in course of treat- 
ment; (2) the charring temperature of these materials; (3) the 
result of treating fabrics without the use of the usual compression 

Specimens of cotton drill and open-mesh jute burlap were cut 
into workable pieces and treated as follows: Eighteen pieces were 
saturated with asphalt at different temperatures ranging from 180 
deg. Fahr. (82 deg. Cent.) to 500 deg. Fahr. (260 deg. Cent.), raised 
by increments of 30 deg. Fahr. ; fourteen pieces were saturated with 
coal-tar pitch at different temperatures ranging from 180 deg. Fahr. 
to 420 deg. Fahr. (215.5 deg. Cent.) raised by increments of 25 deg. 
Fahr. ; ten pieces were saturated with a mixture of asphalt and coal- 
tar pitch in equal proportions; the temperatures of the mixture 
ranged from 300 deg. Fahr. (149 deg. Cent.) to 520 deg. Fahr. (271 
deg. Cent.), raised by increments of 50 deg. Fahr. 

The melting point of the pitch used was about 120 deg. Fahr. 
(49 deg. Cent.) and that of the asphalt about 160 deg, Fahr. (71 deg. 
Cent.), both determined by the cube-in-water method. 

The method of saturating the forty -two specimens was as follows: 
Each piece was drawn slowly, as in practice, through its saturant, 
completely immersed, and, when withdrawn, was hung up imme- 
diately to dry in the air. Of course, this is not the method used by 
manufacturers of waterproofing products for treating fabrics. At 
the factory the felts and fabrics are drawn through steam-heated 
compression rollers immediately after they leave t:^e saturating tank, 
which operation forces the compound into the fibers and removes 
the excess saturating material. (See Fig. 60.) 

It was interesting and instructive to know though what the re- 
sulting condition of the product is when treated as above. All were 
well saturated but excessively coated with bitumen. The burlap 
specimens showed very few or no open meshes remaining. Both the 
asphalt- and pitch-saturated specimens, when weighed, showed a 
gradual decrease in the amount of saturant with the increase of tem- 
perature, but the " A.-P." (asphalt-pitch) mixture saturated 
specimens showed almost constant weight of saturant notwithstand- 
ing increase of temperature; in other words, the " A.-P." mixture 


remained at practically the same consistency while the others became 
more fluid. The pitch-saturated fabrics lost their tackiness first, then 
the "A.-P." saturated fabrics and lastly the asphalt-saturated fabrics. 
The " A.-P/' mixture saturated specimens were devoid of ductility, 
cracked easily on being bent around the finger at normal tempera- 
ture and showed a dull-black, rough and pitted surface. The 
asphalt-saturated and pitch-saturated samples showed a smooth 
and lustrous surface. 

Several specimens of untreated felt, raw burlap and cotton drill 
were then put into a sand bath and heated gradually; at about 
400 deg. Fahr. (204.4 deg. Cent.) the felt charred; at 425 deg. Fahr. 
(218.3 deg. Cent.) the burlap charred and at about 450 deg. Fahr. 
(232.1 deg. Cent.) the cotton drill began to char. The charring 
temperatures thus obtained verified previous values obtained dur- 
ing the saturation process. 

Manifestly the fabrics must be drawn through compression rollers 
to obtain not only good saturation but also the proper amount of 
coating and, in the case of burlap, sufficient open mesh in the finished 
product. The temperature of the saturant has much to do with 
the degree of saturation and is, in fact, almost proportional to it. 
The possibility of charring the felts and fabrics during treatment is 
remote because such temperatures never exceed 350 deg. Fahr. in 
practice and besides, the bitumen, especially the pitch, would be 
injured first by over-heating, and detected by the excessive fumes 
it gives off at the higher (charring) temperatures. The saturant 
composed of equal parts of asphalt and coal-tar pitch is obviously 
not as good as either of the other two when used as a saturant for 


It has often been stated that jute fabric cannot be saturated as 
well as felt. The results noted in Table XVIII indicate that this 
is true for asphalt-treated fabric but quite the reverse for pitch- 
treated fabric. It must, however, be borne in mind that the satura- 
tion of the jute fabric, even with asphalt, is only a preliminary step 
to its final treatment, while with the saturation of the felt its treat- 
ment is completed. This is true of most asphalt- and all pitch- 
treated felts. On the other hand, saturated cotton fabric (satura- 
tion being its only treatment) has 25 per cent more saturant than 
the felt. 


























Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Averages .... 

20 30 




66 . 40 



50 35 








61 . 45 
















Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 
Open-mesh jute fabric 

Felt (light grade) . . 
Felt (light grade) . . 
Felt (light grade) . . 
Felt (light grade) . . 
Felt (light grade) . . 
Felt (light grade) . . 



Felt (light grade) . . 
Felt (light grade) . . 
Felt (light grade) . . 
Felt (light grade) . . 
Felt (light grade) . . 

Felt (heavy grade).. . 
Felt (heavy grade).. . 
Felt (heavy grade).. . 
Felt (heavy grade) . . . 
Felt (heavy grade) . . . 
Felt (heavy grade) . . . 

Cotton fabric 
Cotton fabric 






132 7 

45 52 





It has also been stated that an asphaltic-treating compound for 
jute fabric intended for membrane waterproofing with coal-tar 
pitch as a binder is injurious to the membrane because the two 
materials are forced to mix (on account of the binder being applied 
hot), and produce thereby an inelastic and perhaps deleterious 
compound. Careful investigation, however, seems to show that 
the amount of treating compound used in the fabric is so little in 
comparison with the amount of binder used in the membrane that 
there is no apparent harm in using asphalt-treated fabric with coal- 
tar pitch binder. The results of weights of specimens noted in Table 
XVIII permit the determination of the proportion of treating com- 
pound to binder used to form, say, a 3-ply or a 6-ply membrane; 
for instance, a square foot of a 3-ply fabric membrane, approximately 
J-inch thick, weighs 2 pounds, of which 80 per cent is pitch-binder 
and 15 per cent asphaltic-treating compound. Pitch and asphalt 
in these proportions, were they actually mixed, would not produce 
a very bad compound to be used as a binder. In the field, not more 
than the coating on the fabric mixes with the binder, therefore 
the percentage of treating compound that mixes with the binder 
is still less than that given here. 

Further facts disclosed in Table XVIII are that though asphalt- 
treated jute fabric has only about 75 per cent as much total bitumen 
(that is, saturant plus coating material) as the pitch-treated fabric, 
the amount of coating proper on the asphalt-treated fabric is 45 per 
cent greater than that on the pitch-treated fabric. 

Asphalt-treated and pitch-treated felts of approximately the same 
weights are equally well saturated, but heavy felts contain about 
10 per cent more saturant than lighter felts. 

Effect of Drinking Water on Waterproofing Fabrics. The pur- 
pose of this test is to determine the effect on treated and untreated 
fabric of one-half year's immersion in water and one-half year's 
gradual drying. 

In March, 1914, nine specimens of jute fabric, some treated with 
asphalt and some with coal-tar pitch and one untreated specimen, 
were immersed in plain water, contained in a rectangular tank 
1 by 1 by 3 feet. The specimens were suspended from strings 
stretched across the tank and labeled for identification. The 
water was constantly replenished for six months after which it 
was allowed to evaporate completely, which also took about six 

In March, 1915, the specimens were carefully examined, and the 
following results noted. The untreated jute burlap though thor- 


oughly wet for at least six months, had retained its strength com- 
pletely but was a little stiff and darker in color than originally. 
The bituminous treated specimens showed hardly any loss of strength 
and practically no deterioration. Where the coating on the fabric 
was good originally, the fabric was entirely unaffected, that is, no 
water penetrated the fabric fibers. The bitumen retained its 
elasticity and the fine sawdust, which is sprinkled on the 
surface of the fabric to prevent self adhesion in the rolls 
during shipment and storage, remained intact. Where the fabric 
was poorly saturated, a slight loss of tensile strength was mani- 
fested. In general, however, the asphalt treated specimens showed 
somewhat less resistance than the specimens of fabric treated with 
coal-tar pitch. 

The test proves (1) the value of thoroughly coating and saturating 
the fabric, because thereby it is prevented from absorbing water, 
and (2) that plain water is not particularly injurious to bituminous 
treated fabric. 

Effect of Ground Water on Waterproofing Fabrics. To deter- 
mine the effect on fabrics treated with asphalt and with coal-tar 
pitch by the action of ground water in direct contact with them, 
thirteen specimens of treated jute fabric, each about 4 by 6 inches, 
were buried about 3 feet in the ground at City Hall Park, N. Y., 
near the new Broadway Subway location, for a period of 106 days 
(from May 6th to August 22d, 1914). Table XIX shows the char- 
acteristics of the interred waterproofing fabric. 

In another test similar to the above, various grades of cotton 
fabric, paper fabric and felt were buried in the ground at Battery 
Park, N. Y., at a depth of 4 feet. In less than three months, when 
the specimens were examined, it was found that the cotton and 
paper fabrics had almost completely decayed and the felt had become 
so brittle that it broke in handling. 

Another test of a similar nature with various cotton, jute and felt 
specimens, but this time each heavily coated with pitch or asphalt, 
showed on examination, after 2 months' burial, that both the fabric 
and felt were well preserved though the coatings were considerably 

In each of the above tests the specimens were obtained from 
various manufacturers. 

These tests conclusively prove the necessity of thoroughly coat- 
ing any felt or fabric used as reinforcement in a bituminous water- 
proofing membrane. Also that the binder and not the felt or 
fabric is the waterproofing material in such a membrane- 






(1). 7 oz. open-mesh asphalt- treated 
fabric; well saturated and coated. 

2. 7 oz. open-mesh asphalt- treated 
fabric; well saturated, one side well 
coated, other side poorly coated. 

(3). 7 oz. open-mesh asphalt- treated 
fabric; well saturated and coated. 

(4). 7 oz. open-mesh asphalt-treated 
fabric; poorly coated; not saturated. 

(5) 8 oz. open-mesh oil-tar pitch- 
treated fabric; poorly saturated but 
well coated; pliable. 

(6). 8 oz. open-mesh oil-tar pitch- 
treated fabric; well saturated and 
coated; somewhat stiff and brittle 

(70- Seven pieces of 7 oz. open -mesh 
asphalt- and pitch-treated fabric, more 
or less well saturated and coated. 


Shows almost complete decay. Both 
asphalt and burlap are very brittle. 
No " life " left. 

Shows no strength. Asphalt coating 
very brittle. Burlap saturated with 

Shows brittleness and more or less 
decay. Lacks strength. 

Shows almost complete decay. Very 

Shows almost complete decay. Re- 
mainder is pliable but weak. 

Is brittle, weak and decayed in 
several spots. 

Specimens so badly deteriorated that 
identification is impossible. 

Relative Absorption and Strength of Raw and Treated Water- 
proofing Felts and Fabrics. To determine the relative amount of 
water absorbed by various waterproofing felts and fabrics, and 
also their relative tensile strength and stretch, 88 specimens, of 
which 35 were untreated, and the remainder treated with either 
asphalt or pitch, were partly immersed in water for three hours and 
weighed before immersion and at the end of the first and third hours. 
Then the specimens were allowed to dry, after which they were 
cut into 1-inch strips and tested for strength and stretch on a 
stretching machine. A review of Table XX reveals the following 
facts : 

1. Untreated jute burlap is much more absorbent than paper 
fabric, cotton fabric, felt, building paper, and ready-roofing, all 





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2. Saturated (only) jute burlap is but little more absorbent than 
saturated paper fabric and felt, but much less absorbent than satu- 
rated cotton fabric. 

3. Untreated jute burlap will absorb in one hour about 70 per 
cent, and in three hours about 80 per cent of its weight of water, 
while the same burlap, asphalt-saturated and coated, will absorb 
in one hour only about 2J per cent and in three hours only about 3J 
per cent of its weight of water; while the oil-tar saturated and 
coated burlap will absorb in one hour about 5 per cent and in three 
hours about 6 per cent of its weight of water. 

4. Untreated paper fabric will absorb in one hour about 20 per 
cent and in three hours about 30 per cent of its weight of water, 
while the same paper fabric, coated either with asphalt or pitch, 
will absorb about 4 per cent of its weight of water during both 

5. Untreated cotton fabric will absorb in one hour about 24 per 
cent and in three hours about 27 per cent of its weight of water, 
while the same cotton fabric, treated, will absorb in one hour only 
14 per cent and in three hours only 15 per cent of its weight of water. 

6. Untreated felt will absorb in one hour about 55 per cent and 
in three hours about 70 per cent of its weight of water, while the 
same felt, asphalt-treated, will absorb about 2 per cent and the 
tar-treated felt about 3| per cent of its weight of water during 
both periods. 

7. The tensile strength (of the warp) of asphalt-treated jute 
burlap is increased about 100 per cent and the tar-treated jute 
burlap over 125 per cent, as compared to the untreated burlap. 
The percentage of stretch is diminished by treatment and is less 
for the tar-treated than for the asphalt-treated fabric. 

8. The tensile strength of treated paper fabric is practically the 
same as that of the untreated, but the stretch is only about 50 per 
cent as great. 

9. The tensile strength of treated cotton fabric is about 20 per 
cent more than the untreated, but the stretch is about 200 per 
cent greater. 

10. The tensile strength of asphalt-treated felt is increased about 
300 per cent, and the tar-treated felt about 600 per cent. But the 
stretch is the same for both treated and untreated, this being an 
average of 3 per cent in a 2-inch length. 

The above conclusions are based on consideration only of the 
warp of the fabrics. 

It is interesting to note that ordinary blotting paper is about 200 


per cent stronger than untreated felt of the same weight, but is about 
200 per cent more absorbent, though their unit stretch is the same. 

Immutability Test on Various Waterproofing Felts and Fabrics. 
To determine the effect of exposure to the elements for a period of 
time, thirty-four specimens of waterproofing felts and fabrics, vari- 
ously treated, were left in the open air completely unprotected 
for periods ranging from five to ten months. During the time of 
their exposure they were subjected to rain, hail, snow and sunshine. 
From careful examination of these specimens, the following facts 
are made evident and considered as warranting attention: (1) The 
asphalt-treated fabric is practically unaffected by exposure. (2) 
Oil-tar pitch-treated fabric is not in itself affected, but tends to 
become stiff from the evaporation of the saturant oils. (3) Raw 
and pitch-treated felts are practically unaffected except for the latter, 
which tend to harden and become brittle, due to the evaporation of 
the saturant oils. 

Hence the general conclusion : Pitch-treated felts or fabrics should 
not be stored in the open for more than a few weeks before using, and 
all membrane roofings should receive a top-coating of bitumen 
to preserve the top sheeting. 

Compressibility of Treated Jute-fabric Waterproofing Mem- 
branes. The purpose of this test was to ascertain the amount of 
compression that a waterproofing membrane can withstand without 

Six membranes were tested, two composed of three plies each, 
placed between J-inch mortar discs; two composed of six plies each, 
also placed between J-inch mortar discs, and one composed of six 
plies and one of twelve plies, both without bituminous binder or 
mortar protection discs. 

The asphalt binder used in making half the specimens had a melt- 
ing-point of about 125 deg. Fahr. (52 deg. Cent.) by the K. and S. 
method, and the pitch binder used for making the remaining speci- 
mens had a melting-point of about 120 deg. Fahr. (49 deg. Cent.) 
by the Cube-in- water method. The temperature of the specimens 
was about 75 deg. Fahr. (25 deg. Cent.) when tested. 

When pressure was applied to each of the first four membranes, 
the mortar discs were the first to fail at about 1000 pounds per square 
inch, the membranes remaining uninjured. At about 2000 pounds 
per square inch the fabric began to push out on all sides. When 
pressure was released and the membrane examined it was found that 
when the membrane began to push out radially it was crushed to 
destruction at the center. The two membranes that were tested 


without the binder and mortar discs were not affected at all at a 
pressure of about 3000 pounds per square inch. Both these mem- 
branes were merely compressed and became as hard as a board. 
On tearing the separate plies apart each of them was found to be 
uninjured except for the bituminous coating with which the fabric 
was treated, which had been forced into the open mesh of the fabric. 
This test demonstrates that a built-up, jute fabric membrane 
can safely withstand a direct compression of 1000 pounds per square 
inch; that both pitch and asphalt binder of the melting-points and 
at the temperature indicated above behave alike for membrane 
waterproofing when subjected to compression. 


Specification Requisites. Many architects and engineers are 
not sufficiently familiar with waterproofing engineering, hence, in 
writing specifications, abstractions are freely made from one speci- 
fication and used in another. Such practice is inadvisable and should 
be guarded against. In writing specifications there is usually re- 
quired some of the lawyer's skill in phraseology and the experienced 
engineer's knowledge. For those not so fortunate as to possess 
both these qualities, a few remarks on the writing of waterproofing 
specifications will not be amiss. 

The specification writer should avoid being general, for, to be 
specific is the first requisite of good specification writing. Water- 
proofing specifications, as indeed all specifications, should be written 
open enough to admit of fair competition. They should describe 
the materials, their properties and application well enough to enable 
manufacturers to make them, contractors to apply them, and engi- 
neers or inspectors to approve or reject the materials or their appli- 
cation, or the field work in general, on the strength of such specifica- 
tions. They should be suited to the conditions surrounding the 
particular work. Sufficient instructions should be embodied in the 
specifications to enable the engineer to assure himself that the water- 
proofing work can be properly executed under them. Equivocal 
or incomplete statements should be avoided, while explanatory 
clauses should be inserted wherever necessary. The application 
of waterproofing materials is more difficult and important than their 
manufacture; hence, efficient and sufficient supervision should be 
called for. Specific laboratory tests should also be called for, and 
these should be basic, not supplemental as they often are at present. 
No waterproofing specifications should allow a variation from any 
numerical requirement for strength or composition, as determined 
by test, of anything more than is consistent with best practice for 
the particular property under consideration. Such values are given 
for a great many materials, and will be found in the book of yearly 
proceedings of the American Society for Testing Materials. But 



while the results of some acceptance tests may vary more than others 
the governing values and their significance should be well understood 
before rejecting the material on such grounds. Easy identification 
and proper care of all waterproofing materials in the field should be 
provided for; also, access to the manufactories to observe the mate- 
rials m the various stages of their manufacture. The intent of the 
specifications should be carefully set forth; the price agreed upon a 
lump sum or per unit of completed work. The material alternatives, 
the guarantee and necessary bonds should be clearly set forth. 

These few suggestions well pondered, and a careful study of all 
the conditions under which the work of waterproofing is to proceed, 
coupled with a knowledge of the properties of waterproofing mate- 
rials all in the hands of an experienced engineer or architect would 
result in a type of specification under which litigation would be almost 

The specifications considered herein are fairly representative 
of the advancement that the art of waterproofing has made and which 
it enjoys to-day. The selection is varied enough to be of assistance 
to the architect or engineer in drawing up waterproofing specifica- 
tions for many kinds of structures. The specific information in 
each, though not always complete, is modern and in accord with 
present practice. Several specifications of proprietary waterproof- 
ing materials are included for their suggestive value. The same is 
true of the roofing specifications. Some specifications are given in 
full while only abstracts from others are stated to avoid cumbrance. 
A few original specifications and several specifications of the more 
common materials used in waterproofing engineering are included. 

By a careful perusal and comparison of these specifications, it 
is believed the architect or engineer will find material guidance in 
drawing up explicit and practical waterproofing specifications. 


Treated Woven Cotton Fabric for Membrane Waterproofing. 

Woven cotton fabric for waterproofing purposes shall be made of a 
good grade of cotton. In its raw or untreated state, it shall contain 
no oils of any kind. It shall weigh not less than 5 ounces to the 
square yard and its thread count shall not be less than 50 by 60 
per square inch. To be made into a waterproofing fabric, it shall be 
thoroughly saturated with either asphalt or coal-tar pitch meeting 
the requirements hereinafter specified. No oils or bitumen solvents 
shall be used to liquefy either the asphalt or pitch in order to produce 


a thoroughly saturated fabric. The fabric after treatment shall 
weigh not less than three and one-half times the weight of the 
untreated fabric. During treatment, the temperature of the satu- 
rating material shall not exceed 275 deg. Fahr. (135 deg. Cent.). 
The fabric after treatment shall be elastic and have a stretch in 
either direction of at least five (5) per cent without fracture. A 
1-inch strip, cut with the warp, shall sustain a weight of at least 60 
pounds, and at least 50 pounds with the woof. It must be flexible at 
all temperatures between 32 deg. Fahr. and 150 deg. Fahr. (0 to 66 
deg. Cent.), and shall not flake or crack when folded upon itself. 
It must be of such a nature as to readily conform to any unevenness 
of the surface to which it is applied. 

The asphalt for treating the woven cotton fabric shall be a refined 
product meeting the following requirements: Its melting-point 
by the Kraemer and Sarnow method shall be 155 deg. Fahr. (68 
deg. Cent.); its penetration by the Dow method shall be .30 cm., 
and its ductility not less than 10 cm. nor more than 20 cm. as meas- 
ured on a Smith ductility machine. 

The tar pitch for treating the woven cotton fabric shall be a 
straight-run, coal-tar pitch meeting the following requirements: 
Its melting-point by the cube-in-water method, shall be 110 deg. 
Fahr. (43 deg. Cent.); its penetration by the Dow method, shall 
be 1.5 cm.; the loss on heating in an electric oven, for five hours 
at 325 deg. Fahr. (163 deg. Cent.) shall be not more than 8 per cent 
and its free carbon content shall not be more than 28 per cent nor 
less than 22 per cent. 

Specifications for Bituminous-treated Waterproofing Felt. The 
felt must be saturated with an approved asphalt or coal-tar pitch, 
and must conform to the following requirements: 

The weight per 100 square feet shall be from 12 to 15 pounds 
saturated and 5 to 6 pounds unsaturated. 

The saturation shall be thorough and complete. 

The ash from the unsaturated felt shall not be less than 25 per 
cent by weight. 

The wool in the unsaturated felt shall not be less than 10 per 
cent by weight. 

Soapstone, fine sand, or other substance on the surface of the 
felt to prevent adhesion shall not exceed J pound per 100 square feet 
of felt. 

The asphaltic saturating compound and the coal-tar pitch satu- 
rant shall remain plastic, at ordinary temperatures, after being 
heated to 325 deg. Fahr. (163 deg. Cent.) for ten hours. 


Both the asphalt- and tar-pitch-treated felts shall be soft, pliable 
and tough when received from the factory and until placed in the 

The quotient obtained by dividing the tensile strength in pounds, 
of a strip 1 inch wide cut lengthwise, by the weight in pounds of 
100 square feet shall not be less than 7, and, when cut crosswise, 
shall not be less than 3J. 

The strength saturated shall be at least 25 per cent more than 
the strength unsaturated, taken lengthwise (along the warp) and at 
least 15 per cent more taken crosswise (along the woof). 

Remarks. The above specification applies mainly to a light- 
grade felt, such as is commonly used for roofing. A wool-content 
of 25 per cent produces the best felt, but unfortunately this has been 
reduced to practically zero in the ordinary felts used at the present 
time. The requirements for weight and strength called for is readily 
exceeded by an average good felt. Only the former, though, is 
important, since it is an index of the amount of preserving material 
in the felt. 

Specifications for Bituminous-treated Jute Fabric for Water- 
proofing. Jute fabric for waterproofing purposes shall be made of 
jute burlap, saturated and coated with bitumen, and if necessary 
sprinkled with sawdust to prevent adhesion in the roll. 

The burlap shall have a trade weight rating of either seven and 
one-half (7J) ounces or eight (8) ounces per square yard and shall 
show a uniform open mesh with a uniform thickness of thread in 
both the warp and the woof. 

The bitumen used for saturating and coating the burlap shall be 
asphalt or coal-tar or oil-tar pitch meeting the following require- 
ments : 

The coal-tar pitch shall be either a straight-run pitch containing 
not less than 25 per cent, and not more than 32 per cent of free carbon ; 
or an oil-tar pitch containing not less than 10 per cent of free carbon. 
The coal-tar or oil-tar pitch used as saturant shall melt at approxi- 
mately 70 deg. Fahr. (21 deg. Cent.). The coal-tar or oil-tar pitch 
used as coating shall melt at approximately 175 deg. Fahr. (80 deg. 
Cent.). The melting-points are to be determined by the cube-in- 
water method. 

The asphalt shall contain in its refined state not less than 98J 
per cent of bitumen soluble in cold carbon tetrachloride. The 
remaining ingredients shall be such as not to exert an injurious effect 
on the burlap. 

The asphalt, both saturant and coating shall not flash below 


350 deg. Fahr. (177 deg. Cent.) when tested in the New York State 
Closed Oil Tester. When heated in an electric oven for five hours 
at a temperature of 325 deg. Fahr. (163 deg. Cent.) it shall not lose 
over two (2) per cent by weight, nor shall the penetration at 77 deg. 
Fa"hr. (25 deg. Cent.) after such heating be less than one-half of the 
original penetration. 

The melting-point of asphalt saturant shall be between 100 and 
115 deg. Fahr. (38 and 46 deg. Cent.) and of asphalt coating, approxi- 
mately 225 deg. Fahr. (107 deg: Cent.) as determined by the Kraemer 
and Sarnow method. 

The consistency of the asphalt shall be determined by the pene- 
tration, which must be between 0.75 and 1.00 cm. for the saturant, 
and between 0.15 and 0.25 cm. for the coating. 

A briquette of the saturant of a cross-section of 1 sq. cm. shall 
have a ductility of not less than fifty (50) centimeters and of the 
coating not less than five (5) cm. at 77 deg. Fahr. on a Smith ductility 

All tests herein specified must be conducted according to methods 
approved by the engineer. 

The very fine sawdust shall be a granulated cedar, pine, or other 
suitable wood, and applied on one side of the fabric so that not 
more than 5 ounces will cover 100 square feet. 

The burlap shall be thoroughly dried before being saturated; 
it shall be thoroughly saturated and coated with bitumen, but 
shall retain between 30 and 40 per cent of the open mesh of the un- 
treated burlap. The fabric after treatment shall be pliable without 
flaking at all working temperatures after treatment. 

The temperature of the saturant and coating materials during 
the process of treating the fabric shall not exceed 300 deg. Fahr. 
(149 deg. Cent.). 

The machinery and method of saturating and coating the burlap 
shall be subject to the approval of the engineer. 

The treated fabric shall have a tensile strength in the direction 
of its length (warp) of not less than eighty (80) pounds and in the 
direction of its width (woof) , not less than sixty (60) pounds per lineal 
inch of test specimen. 

The fabric, when examined under a magnifying glass, shall show 
the inner strands to be actually saturated and the outer strands well 
coated. A piece of fabric ripped along a line diagonal to the warp 
and the woof shall show thorough saturation of the strands. The 
percentage of open mesh may be approximated by holding a large 
piece of fabric before a light. 


The finished fabric shall weigh not less than two and one-half 
times nor more than three and one-half (3J) times the weight 
of the raw burlap. 

The finished roll of fabric shall unroll easily. The completed 
fabric shall be wound on a core or spool of wood, fiber or other strong 
material, not less than two (2) inches in its smallest dimension, and 
equal in length to the width of the fabric. 

The fabric shall be delivered in rolls not exceeding one hundred 
seventy-five (175) feet in length. The width shall not be less than 
three (3) feet. The shrinkage due to saturation shall not exceed 
two (2) per cent. When the fabric is brought on the work it shall be 
stored in a dry and cool place, piled no more than four rolls high, 
never stood on ends, and protected against rain and other weather 
conditions as well as from injury from resting or falling weights. 

Remarks. The above specifications are probably the most com- 
plete of their type. Fabric made according to them has been used 
very extensively and very successfully on the New York Subway 
System. Engineers sometimes contend that it is unnecessary to 
saturate and coat burlap, arguing that the bituminous binder applied 
on the work is sufficient to protect it. Experience has proven that 
saturation and coating of the fabric is essential for best results. 
The practice of applying untreated burlap, never very extensive, 
is gradually being abandoned. 

Specifications for Asphalt for Waterproofing or Dampproofing.* 
These specifications cover asphalt for waterproofing and damp- 
proofing recommended for use under uniformly moderate tempera- 
ture conditions. 

The melting-point shall be between 100 and 140 deg. Fahr. (38 
and 60 deg. Cent.) as determined by the ball-and-ring method, 
and shall be specified for one of the following classes: 130 to 140 
deg. Fahr. (54.5 to 60 deg. Cent.); 115 to 130 deg. Fahr. (46 to 54.5 
deg. Cent.); 100 to 115 deg. Fahr. (38 to 46 deg. Cent.). 

The penetration at 77 deg. Fahr. (25 deg. Cent.), under a load of 
100 grams for 5 seconds, shall be not less than 50 nor more than 

The penetration shall bear the following relation to the melting- 
point: Penetration of 50 to 75 for melting-points between 130 and 
140 deg. Fahr. Penetration of 75 to 100 for melting-points between 
115 and 130 deg. Fahr. Penetration of 100 to 125 for melting- 
points between 100 and 115 deg. Fahr. 

* Proposed tentative specifications, Proceedings American Society for Test- 
ing Materials, Vol. 17, pp. 712-722 (1917). 


The ductility at 77 deg, Fahr. (25 deg. Cent.), when a briquette 
of the material having a minimum cross-section of 1 sq. cm. is pulled 
apart at the rate of 5 cm. per minute, shall not be less than 30 cm. 

The specific gravity shall not be more than 1.08 at 77/77 deg. 
Fahr. (25/25 deg. Cent.). 

The bitumen soluble in cold carbon bisulphide shall not be less 
than 95 per cent. 

The loss of a 50-gram sample on heating at 325 deg. Fahr. (163 
deg. Cent.), for five hours, shall not exceed 1 per cent. The pene- 
tration of the residue from this test shall not be less than 50 per cent 
of the original penetration. 

The ash shall not exceed 4 per cent. 

Specifications for Primer for Use with Asphalt for Waterproofing 
or Dampproofing.* These specifications cover primer for use when 
specified with asphalt for waterproofing or dampproofing. 

The primer shall consist of an asphaltic base, complying in 
every respect with the specifications of asphalt for waterproofing 
below grade (page 267), which shall be thinned to ordinary paint 
consistency with a petroleum distillate having an end point on 
distillation not above 500 deg. Fahr. (260 deg. Cent.). Not more 
than 20 per cent of this petroleum distillate shall distill under 
248 deg. Fahr. (120 deg. Cent.). 

Specifications for Asphalt for Waterproofing Surface and Sub- 
surface Structures.! Asphalt shall be used which is of the best grade, 
free from coal tar or any of its products, and which will not volatilize 
more than \ of 1 per cent under a temperature of 325 deg. Fahr. 
(163 deg. Cent.) for seven hours. 

It must not be affected by a 20 per cent solution of ammonia, 
a 25 per cent solution of sulphuric acid, a 35 per cent solution of 
muriatic acid, nor by a saturated solution of sodium chloride. It 
should show no hydrolytic decomposition when subjectec .. for a period 
of ten hours, to hourly immersions in water with alternate rapid 
dryings by warm air currents. 

For metallic structures, exposed to the direct rays of the sun, 
the asphalt must not flow under 200 deg. Fahr. (93.5 deg. Cent.), 
nor become brittle at deg. Fahr. ( 17.7 deg. Cent^ /vhen spread 
on thin glass. 

For structures under ground, such as masonry arcl 53, abutments, 
retaining walls, foundation walls of buildings, subways, etc., a flow 

* Proposed tentative specifications, Proceedings American Society for Testing 
Materials, Vol. 17, Part 1, pp. 712-722 (1917). 
f Chicago & Northwestern Railway Company. 


point of 180 deg. Fahr. (82 deg. Cent.) and a brittle point of deg. 
Fahr. will be required. 

A mastic made from either grade of asphalt by mixing it with 
sand in the proportion of 1 of asphalt to 4 of sand, must not percepti- 
bly indent, when at a temperature of 130 deg. Fahr. (54.5 deg. Cent.) 
under a load of 20 pounds per square inch. It must also remain 
pliable at a temperature of deg. Fahr. 

Remarks. It may be noted that the above specifications call 
mainly for physical tests. The kind of asphalt specified must 
necessarily be fluxed, as neither natural nor artificial asphalts can, 
of themselves, meet the above requirements. Yet the few tests called 
for are undoubtedly sufficient to guarantee the quality of the asphalt, 
for the loss on heating test limits the amount and grade of fluxing 
material, and the flow point and brittle point requirement limits 
the grade and quality of the original asphalt. Unless both of these 
materials are of the proper consistenty and properly blended, the 
results of the tests would not check with the requirements. The 
test requirements of the aboye specifications are a material departure 
from the almost standard requirements for waterproofing asphalts, 
which usually call for a melting-point test, loss on heating, solubility 
in carbon bisulphide or carbon tetrachloride, solubility in petrolic 
ether, penetration, ductility, and specific gravity. 

In the flow-point test requirement, a time limit should be speci- 
fically stated, as also in the indent test for mastic, because neither 
the asphalt nor the mastic will fulfill the requirements in unlimited 
time. It would seem, though, that one of the so-called melting- 
point tests would be better to use then the flow-point test because 
the function of the latter is primarily to show the relative flowing 
properties of bituminous, and besides, it is not extensively used in 
the industry. 

Specifications for Coal-tar Pitch for Waterproofing and Damp- 
proofing.* These specifications cover coal-tar pitch for waterproofing 
and dampproofing recommended for use under uniformly moderate 
temperature conditions. 

The melting-point as determined by the cube-in- water method, 
shall be between 120 and 140 deg. Fahr. (49 and 60 deg. Cent.). 
In specifying the melting-point desired within the above limits, a 
variation of not more than 5 deg. Fahr. (2.5 deg. Cent.) in either 
direction will be permitted. 

The penetration at 77 deg. Fahr. (25 deg. Cent.), under a load of 

* Proposed tentative specifications, Proceedings American Society for Testing 
Materials, Vol. 17, Part 1, pp. 712-722 (1917). 


100 grams for five seconds shall not be less than 20 nor more 
than 120. 

The ductility, at 77 deg. Fahr. when a briquette of the material 
having a minimum section of 1 sq. cm. is pulled apart at the rate 
of 5 cm. per minute shall not be less than 40 cm. 

The loss of a 20-gram sample on heating at 325 deg. Fahr. (163 
deg. Cent.) for five hours on pitch of melting-point between 120 and 
130 deg. Fahr. (49 and 54.5 deg. Cent.) shall not exceed 9 per cent, 
and on pitch of melting-point between 130 and 140 deg. Fahr. (54.5 
and 60 deg. Cent.) shall not exceed 7 per cent. 

The specific gravity of the pitch at 77/77 deg. Fahr. (25/25 deg. 
Cent.) shall not exceed the limits of 1.24 and 1.34. 

The specific gravity at 140/140 deg. Fahr. (60/60 deg.Cent.) of the 
distillate to 671 deg. Fahr. (355 deg. Cent.) shall not be less than 1.06. 

The matter soluble in hot toluol-benzol shall not be less than 65 
nor more than 85 per cent. 

The ash shall not exceed 1 per cent. 

Specifications for Creosote Oil for Priming Coat with Coal-tar 
Pitch for Waterproofing and Dampproofing.* When it is specified 
that previous to the mopping on of the hot coal-tar pitch, the wall, 
floor, or foundation, shall be painted with a priming coat, the following 
specifications for creosote oil shall apply: 

Creosote oil shall be of pure tar distillate, free from any sub- 
stance foreign to a tar distillate. 

The oil shall be entirely fluid at 100 deg. Fahr. (38 deg. Cent.). 

The specific gravity at 100 deg. Fahr. shall not be less than 1.00 
nor more than 1.06. 

Insoluble matter in hot benzol shall be less than 1 per cent. 

When distilled, it shall yield: (a) water not more than 2 per cent; 
(b) not more than 5 per cent shall distill under 392 deg. Fahr. (200 
deg. Cent.); (c) not more than 50 nor less than 30 per cent shall 
distill under 455 deg. Fahr. (235 deg. Cent.) : (d) the residue above 
671 deg. Fahr. (355 deg. Cent.) shall not exceed 15 per cent; (e) 
the residue shall be soft; (/) the specific gravity at 100 deg. Fahr. 
(38 deg. Cent.) of the fraction distilling between 455 and 599 deg. 
Fahr. (235 and 315 deg. Cent.), shall not be less than 1.00. 

Coal-tar Pitch for Mastic Waterproofing. Coal-tar pitch in- 
tended for mastic for brick-in-mastic waterproofing shall be a 
straight-run residue obtained from the distillation of coal tar and 
shall meet the following requirements- 

* Proposed tentative specifications, Proceedings American Society for Testing 
Materials, Vol. 17, Part 1, pp. 712-722 (1917). 



The melting-point shall be not less than 116 nor more than 122 
deg. Fahr. (47 and 50 deg. Cent.), determined by the cube-in-water 
method. The penetration (Dow machine) at 77 deg. Fahr. (25 
deg. Cent.) with 100 grams acting for five seconds, shall be not 
more than 180 and not less than 110. 

The matter insoluble in hot extraction in benzol and toluol shall 
be not less than 24 and not more than 32 per cent. 

The ash shall not exceed 1 per cent. 

On distillation to 671 deg. Fahr. (355 deg. Cent.), the specific 
gravity of the total distillate shall be not less than 1.06, determined 
at 140/140 deg. Fahr. (60/60 deg. Cent.). 

Remarks. Coal-tar pitch meeting the above specifications has 
not yet been used for making waterproofing mastic. In fact, no 
coal-tar pitch has ever been used for the purpose mentioned in the 
specifications, because it was always considered impossible to obtain 
a tar-pitch that would be at all plastic at 32 deg. Fahr. (0 deg. Cent.). 
But as a result of extensive tests a grade of pitch has been evolved in 
which this objection has been overcome. The above specification 
is based on that series of tests. The method of making mastic is 
explained in Chapter II. 

Hydrated Lime for Integral Waterproofing.* Hydrated lime is 
a dry flocculent powder resulting from the hydration of quicklime. 
It is commercially divided 'into four classes: (a) High calcium; 
(6) calcium; (c) magnesian; (d) high-magnesian. 

The classes and chemical properties of hydrated lime shall be 
determined by standard methods of chemical analysis. 

The non- volatile portion of hydrated lime shall conform to the 
following requirements as to chemical composition : 


Properties Considered. 

High Calcium. 




Calcium oxide. ..... 

Per Cent. 

90 (min.) 

Per Cent. 


Per Cent. 

Per Cent. 

Magnesian oxide 


Sufficient to 
hydrate the 

25 (min.) 

Sufficient to 
hydrate the 

Silica alumina oxide 
of iron (max.) 
Carbon dioxide (max.). . 
Water. . 

Sufficient to 
hydrate the 

Sufficient to 
hydrate the 

Book of American Society for Testing Materials Standards, p. 472, 1916. 


A 100-gram sample shall -leave by weight a residue of not over 
five (5) per cent on a standard 100-mesh sieve and not over 0.5 per 
cent on a standard 30 mesh-sieve. 

Hydrated lime shall be tested to determine its constancy of 
volume in the following manner : 

Equal parts of the hydrated lime under test and volume-con- 
stant Portland cement shall be thoroughly mixed together and 
gaged with water to a paste. Only sufficient water shall be used 
to make the. mixture workable. From this paste a pat about 3 
inches in diameter and J inch thick at the center, tapering to a thin 
edge shall be made on a clean glass plate about 4 inches square. 
This pat shall be allowed to harden twenty-four hours in moist 
air and shall be without popping, checking, cracking, warping or 
disintegration after five hours' exposure to steam above boiling water 
in a loosely closed vessel. 

The sample shall be a fair average of the shipment. Three per 
cent of the packages shall be sampled. The sample shall be taken 
from the surface to the center of the package. A 2-pound sample to 
be sent to the laboratory shall immediately be transferred to an air- 
tight container, in which the unused portion shall be stored until 
the hydrated lime has been finally accepted or rejected by the 

Hydrated lime shall be packed eitfier in cloth or in paper bags 
and the weight shall be plainly marked on each package. 

The name of the manufacturer shall be legibly marked or tagged 
on each package. 

All hydrated lime shall be subject to inspection. 

The hydrated lime may be inspected either at the place of manu- 
facture or the point of delivery, as arranged at the time of purchase. 

The inspector representing the purchaser shall have free entry 
at all times while work on the contract of the purchaser is being per- 
formed, to all parts of the manufacturer's works which concern the 
manufacture of the hydrated lime ordered. The manufacturer shall 
afford the inspector all reasonable facilities for inspection and 
sampling, which shall be so conducted as not to interfere unneces- 
sarily with the operation of the works. 

The purchaser may make the tests to govern the acceptance or 
rejection of the hydrated lime in his own laboratory or elsewhere. 
Such tests, however, shall be made at the expense of the purchaser. 

Unless otherwise specified, any rejection based on failure to 
pass tests prescribed in these specifications shall be reported within 
five working days from the taking of samples. 


Samples which represent rejected hydra ted lime shall be pre- 
served in airtight containers for five days from the date of the test 
report. In case of dissatisfaction with the results of the tests, the 
manufacturer may make claim for a rehearing within that time. 

Remarks. The above specifications will be of material aid to 
the architect and engineer in obtaining a product dependably suit- 
able forjwaterproofing by the integral method. Though it is claimed 
that there is little or no difference which grade of hydrated lime is 
used, still, the following facts have positively been ascertained: 
The high magnesian lime (25 to 40 per cent magnesia) though it 
slakes and sets more slowly, takes up less water, generates less heat 
and expands and shrinks less than the high calcium lime; also that 
even ordinary magnesian lime (5 to 25 per cent magnesia) works 
more smoothly and though it also sets slower, it is stronger than high* 
calcium lime. 



Specifications for Dampproofing Concrete with Coal Tar. The 

concrete surface to be dampproofed should be smooth, thoroughly 
clean and dry. The entire surface should be mopped with a coating 
of dead oil, using all that the concrete will absorb. If applied in 
cold weather, the dead oil should be heated; in hot weather it can 
be applied cold. 

The dead oil should conform to the Specifications for Creosote 
Oil for Priming Coat with Coal-tar Pitch for Waterproofing and 
Dampproofing, page 270. 

When the entire surface is completely mopped with the dead oil, 
it should be remopped with a straight-run coal-tar pitch, following 
same with additional moppings until the whole surface has a bright, 
patent-leather appearance.' The coal-tar pitch should conform to 
the Specification for Coal-tar Pitch for Waterproofing and Damp- 
proofing, page 269. 

Both the dead oil and the coal-tar pitch must be delivered on the 
work in packages that are plainly marked with the manufacturer's 
brand, and indicating the grade and quality of the material. 

Waterproofing Flat Concrete Surfaces with Coal-tar Pitch Mastic. 
The mastic shall consist of gravel, sand and coal-tar pitch. The 
materials shall be mixed together in the proportion of three parts of 
gravel, two parts of sand, and one part of coal-tar pitch by volume. 
The sand and gravel shall be thoroughly dried, and all materials 


heated sufficiently to permit thorough mixing, but in no case shall the 
temperature exceed 300 deg. Fahr. (149 deg. Cent.). 

The gravel shall be from f to f inch in size. 

The sand shall pass 100 per cent through an 8-mesh sieve. 

The pitch shall have a melting-point of about 125 deg. Fahr. 
(52 deg. Cent.) by the cube-in-water method. 

The mixture shall be spread over the surface to the required thick- 
ness, compacted either by tamping or rolling, and given a mopping 
of coal-tar pitch the same as is used in the mixture. 

If ballast is to be applied directly on the mastic, the latter should 
be 2 inches thick. If there is sufficient space to allow for a sand 
cushion above the mastic, 1J inches of mastic is sufficient. 

Remarks. The above specifications are concise but somewhat 
incomplete. By specifying a |-inch (maximum size) gravel; the in- 
corporation of at least one part cement or limestone dust in place 
of one of the parts of gravel; and more test requirements for the 
pitch, such as free carbon content, specific gravity of distillate oils 
and penetration (which would permit identification of the pitch on 
the work), a more certain grade of mastic would result. 

Specifications for Waterproofing Concrete Structures by the 
Integral Method. Watertightness shall be secured by the addition 
of A * into the mass or by plastering or veneering the interior or 
exterior of the structure with a continuous coat of waterproofed 
cement mortar. 

Concrete should consist of one (1) part of cement, two (2) or three 
(3) parts of sand and four (4) or five (5) parts of stone each to meet 
standard requirements. The quantity of A to be used is 8 to 16 
pounds per cubic yard of puddled concrete. Introduce the water- 
proofing at the mixer, by mixing it into water first. 

Placing of concrete shall be continuous throughout definite 
stages and joints between different days' work shall be carefully 
treated to obtain positive bond. 

Cement mortar shall be prepared by thoroughly tempering a dry 
mixture of one (1) part of cement to either two (2) or three (3) parts 
of sand with water to which A has been added as follows : 

Under ordinary conditions 10 pounds per cubic yard of mortar; 
permanent ground water, 16 to 24 pounds per cubic yard of mortar; 
ground water pressure, up to 32 pounds per cubic yard of mortar; 
the mortar to be \ to 1 inch thick. 

The continuous cement coat must be applied in several layers 

* These specifications are for the use of a proprietary calcium-oleate com- 
pound, herein designated by A. 


after the underlying concrete has been cleansed of dust and dirt. 
The concrete surface should be washed with a 10 per cent solution 
of acid water and afterward rewashed thoroughly with clear water 
to remove the acid. 

The prime or scratch coat is to be well troweled. 

The final coat must be floated with a wooden or cork float to 
avoid air-cushions. The work is to be protected against the rays of 
the sun or in winter against freezing. 

Keep mortar damp so as to prevent too rapid drying. 

Remarks. The above specifications are cited merely because 
they are typical of many of those issued for proprietary integral 
waterproofing compounds. It is explicit enough, but since no state- 
ment of composition or properties of the waterproofing compound 
is included, what may be expected of the use of the material depends 
upon the integrity of the manufacturers. In Chapters II and X 
will be found information which should be consulted before the above 
type of specifications are accepted as a model by the architect or 

Specifications for Waterproofing Concrete and Masonry Struc- 
tures by the Integral-mortar Surface Coating Method. It is the 
intent of these specifications to obtain a watertight structure. 

Watertightness shall be secured by plastering the interior sur- 
face of the structure with a continuous coat of Portland cement 
mortar waterproofed with B * waterproofing paste. 

The mortar composing the plaster coat shall consist of one (1) 
part of cement and two (2) parts of sand, to meet the following 

The cement shall be a high-grade Portland, which has been care- 
fully tested and found to satisfactorily meet the requirements of the 
Standard Specifications of the American Society for Testing Materials 
and preferably ground so that eighty per cent (80%) shall pass a 
standard two hundred (200) -mesh sieve. 

The sand shall consist of spherical grains of any hard rock that 
is practically free from clay, absolutely free from organic matter, 
and uniformly graded in size from coarse to fine. 

The waterproofed cement mortar shall be prepared by thoroughly 
tempering (to required consistency) a dry mixture of one (1) part of 
cement and two (2) parts of sand, with water to which B waterproof- 
ing paste has been added in the proportion of one (1) part of paste 
to eighteen (18) parts of water, as directed by the manufacturer. 

* These specifications are for the use of a proprietary alum-soap paste 
compound, herein designated by B. 


Before plastering the cement mortar on the hardened concrete, 
the surface of same shall be treated as indicated in the following: 

The hardened surface shall be mechanically roughened by chip- 
ping and very thoroughly cleaned with a heavy wire broom, so as to 
remove all dust and dirt. A jet of steam shall be employed to clean 
the wall, if available. 

To the mechanically cleaned surface apply with a large acid 
brush, a liberal coat of one to ten (1 : 10) solution of hydrochloric 
acid (muriatic acid) . Allow the acid to remain until it has exhausted 
itself, which will require at least ten minutes. Apply a second coat 
of acid solution. if the first does not sufficiently clean and expose 
the surface of the aggregate. 

With a hose under good pressure, slush the surface so as to remove 
the salts and loose particles resulting from the action of the acid. 
Continue the slushing until the old concrete is thoroughly cleaned and 
soaked to its full capacity. Thoroughly wire-brush the surface so 
as to remove the particles which have been loosened by the action 
of the acid. 

To the cleaned saturated surface apply with a strong fiber brush 
a coating of pure cement mixed to a thick creamy consistency with 
water to which B waterproofing paste has been added in the pro- 
proportion of one (1) part of paste to eighteen (18) parts of water. 
Rub in vigorously so as to fill all crevices and cavities produced by 
the action of the acid. 

Immediately after applying the above slush coat, the first coat 
of waterproofed cement mortar shall be applied to a thickness of 
three-eighths (f) of an inch directly on the slush coat, and well 
troweled and rubbed into the crevices of the surface. This first 
coat shall be lightly scratched before showing initial set. Before 
this first coat has reached its final set, the second coat shall be applied, 
of equal thickness, so as to give a full average thickness of three- 
quarters (|) of an inch. Special care shall be exercised to apply 
this finish coat before the first coat has reached its final set. The 
finish coat shall be thoroughly floated to an even surface and sub- 
sequently troweled free from any porous imperfections. 

Where water is running through the wall, proper drainage must 
be provided by drilling holes and inserting tubes in the wall, to con- 
centrate the flow of water. With the pressure relieved, the water- 
proofed plaster coat shall be applied to the drained portions of the 
wall. The drainage pipes shall remain open until the waterproofed 
plaster coat has thoroughly set and is capable of resisting the pressure 
by its own adhesive strength, when the drainage pipes shall be closed 


with suitable plugs and coated with the waterproofed cement 

The floors shall be prepared and treated exactly as indicated 
above, and finished with a waterproof cement mortar to a thickness 
of two (2) inches. Special care should be exercised to bond the wall 
coating to the floor coating, so as to make the waterproofed coating 
continuous over the entire surface. 

When hardened, the waterproofed plaster coat shall be sounded 
with a light hammer and all loose and defective plaster shall be cut 
out and replaced. 

Remarks. Consistent with proprietary waterproofing materials 
specifications the one above does not mention anything about the 
property or quality of the compound specified. Neither is there 
included a guarantee that the application of this material will make 
a watertight job for any period of time. On small or unimportant 
work, the engineer or architect may permit waterproofing under 
the above type of specifications, but for large or difficult work 
careful investigation and technical and practical tests are essential. 
This procedure would undoubtedly tend toward final economy and 
more certainty of results. 

Specifications for Waterproofing Cement Stucco by the Integral 
Method. The materials composing the stucco should consist of: 
Twelve parts clean sharp sand; one part hydrated lime; five parts 
standard Portland cement. 

The waterproofing paste * should be mixed : One part water- 
proofing paste; eighteen parts water. 

The paste should be dissolved in one part of water to insure a 
perfect blending, after which add the other seventeen parts water 
and stir until smooth. 

The cement and hydrated lime should be mixed to a uniform 
color, before sand is added, then add sand and mix again to a uniform 
color, after which add the waterproofed water, or " milk " obtained 
as per preceding paragraph. This mortar must be well " worked " 
and applied immediately. No mortar should be used after standing 
more than thirty minutes. 

All stucco should be two-coat work. The first coat should be 
mixed as above with the addition of sufficient long cow hair for key- 
ing, when applied to metal lathe. If on masonry, the surface must 
be saturated with water before applying and the plaster applied before 
base is dry. 

* The waterproofing paste referred to in these specifications is a quasi-soap 
or quasi-colloidol paste. 


After the first coat has been applied it should be roughened so 
as to form a base for keying the finishing coat, which must be floated 
in order to densify the plaster. 

The finished stucco must be kept wet for four or five days by 
covering with burlap or other suitable material and sprinkled at 
least twice a day. 

Remarks. The remarks appended to the preceding specifica- 
tions also apply here. The hydrated lime called for in this speci- 
tion is of itself an efficient waterproofing agent. 

Specifications for Waterproofing Foundations by the Membrane 
System. The foundation shall be waterproofed, so that the interior 
will be permanently free from moisture, by a continuous sheet of 
waterproofing surrounding the exterior and bottom to the height 
directed by the engineer. 

The surface of all masonry upon which the waterproofing is to 
be applied shall be comparatively smooth and as dry as is practic- 

Coat the entire surface on which the waterproofing is to be applied 
with tar pitch,* into which, while hot, imbed a layer of treated felt,f 
following this with alternating layers of felt and pitch until five 
layers of felt and six moppings of pitch have been applied. All felt 
must be bedded into the pitch while the latter is still hot but in no 
place shall felt touch felt. 

At all wall angles, corners and any place 'where in the opinion of 
the engineer the waterproofing course will be subjected to unusual 
strain, there shall also be used one layer of reinforced felt t and an 
additional mopping of pitch. Where laps are left to be connected 
after other work is completed, they shall be not less than 10 inches 
wide and at least two of the five plies shall be of reinforced felt, and 
care shall be taken to protect such laps while other work is in progress. 

Where waterproofing is applied on the exterior of perpendicular 
walls, it must be permanently protected by a layer of concrete or 
course of brick, and until such permanent protection is in place, 
care must be taken not to break or injure the waterproofing in any 
way. On horizontal waterproofing the temporary protection must 
be 1 inch of cement mortar applied immediately after the felt and the 
pitch are laid. 

* A straight-run coal-tar pitch, having a melting-point between 140 and 150 
deg. Fahr. by the cube-in-water method. 

t A tar-saturated felt of good grade and medium weight. 

t This reinforced felt is composed of one layer of tar-saturated felt bonded 
to one layer of unsaturated cotton-woven fabric. This combination is used as a 
single ply in itself. . . 



On all interior waterproofing, the permanent covering must be 
of sufficient weight and strength to withstand the maximum water 

Specifications for Waterproofing Subsurface Structures by the 
Integral Motor Surface Coating Method. Waterproofing shall con- 
sist of cement mortar facings waterproofed with C.* These facings 
(or coatings) shall be applied to those surfaces of walls (interior or 
exterior below grade); upper surface of floor slabs; basement and 
sub-basement; pits, tunnels, etc., where waterproofing is indicated 
in plans and specifications. 

The mortar for these facings shall be composed of one part of 
cement of brand approved by architect, two parts of clean sharp 
sand, to which shall be added 1J gallons of C for each bag of cement. 

These waterproof facings shall be from f to 1 inch applied in at 
least two coats on walls and not less than 1 inch thick applied in 
one coat on floor surfaces. The finish coat shall be well floated to 
close all pores. 

Thoroughly mix the cement and sand dry. 

Put enough C for one batch into an empty barrel and add a small 
quantity of water, stirring until entirely smooth. Then stir in more 
water, but not more than will be required to give a stiff mortar. 

Mix this liquid in the cement and sand as usual, turning over 
until the color of the mortar is uniform. 

The measured amount of C may be added to the charge in a 
batch mixer without first dissolving in the gaging water; no more 
than the usual time of mixing is needed. 

Where the masonry is new, clean and rough, it is necessary merely 
to saturate the surface with water. It is very important to use as 
much water as the surface will take up; otherwise the mortar will 
be sucked dry before it has a chance to set properly. 

Old surfaces, such as smooth concrete, brick- work, stone, etc., 
must be chipped, bush-hammered or sand-blasted until suitably 
rough; rubbed with a wire scratch-brush to remove loose particles, 
paint, slime, etc.; washed with dilute muriatic acid (mixed one to 
four in a wooden pail), and finally flushed down with clean water to 
remove all traces of acid. After seeing that the wall is saturated 
v/ith water, the mortar must be applied as soon as possible. 

Over a very hard, seasoned concrete, a thin cement wash, applied 
before the mortar coat, and allowed to harden slightly, will promote 
the adherence of the new mortar. ,* 

* These specifications are for the use of a proprietary asphaltic-emulsion 
paste compound, herein designated by C. 


C waterproofing compound will not make up for careless or un- 
skilled labor. The precautions of ordinary good practice must be 
observed in every point, just as if C were not used. 

Remarks. The company issuing the above specifications is 
frank enough to admit that the material it specifies will not make 
up for careless or unskilled labor, and that the precautions of good 
practice must be observed in every point if the waterproofing mate- 
rial is to be effective. In Chapters II and X will be found facts 
and figures showing what may be accomplished by the use of experi- 
enced labor and careful supervision without the addition of any in- 
tegral waterproofing, if the importance of the work warrants the 
expense of these extra precautions. 


Specifications for Waterproofing New York Subways * by the 
Membrane and Brick-in-mastic Systems. General Directions. In 
general, waterproofing of the structure will be limited to the roof 
and to those surfaces near ground water or mean high water if ground- 
water level is found for any reason to be below mean high water. 
At other places free drainage shall be provided by pipe drains, hollow 
tile or broken stone. 

At the stations the entire structure shall be waterproofed. 

The protecting masonry shall be concrete, common bricks or 
hollow terra-cotta blocks as directed, and shall be not less than four 
(4) inches in thickness. 

In places where permanent sheeting is placed at the waterproofing 
line, the waterproofing, if permitted by the engineer, may be applied 
against the sheeting. 

All surfaces to which waterproofing is to be applied shall be made 
as smooth as possible; on these surfaces there shall be spread hot 
melted coal-tar pitch in a uniformly thick layer; on this layer of 
pitch shall be laid a treated woven fabric of such material as may be 
approved by the engineer; this process shall be repeated until such 
number of layers as may be required by the engineer have been placed 
and a final coat of the pitch shall then be applied. 

The term " ply " as used in these specifications shall mean a layer 
of treated woven fabric (except the dry-ply), both sides of which 
shall be coated with coal-tar pitch at the time of laying. 

The number of plies of waterproofing over the roof between sta- 

* Dual Subway System built under supervision of Public Service Commission 
for the First District, State of New York, D. L. Turner, Chief Engineer. 


tions shall in no case be less than three (3), except as hereinafter 
provided where brick laid in asphalt mastic is used. 

On the sidewalls at the station the same conditions as in the pre- 
ceding paragraph shall apply. 

On the sides and bottom of the structure below a line two (2) 
feet above ground water, or, if ground water is below mean high- 
water level, then (2) feet above mean high water, one (1) ply of water- 
proofing, as described above, shall be used with one or more courses 
of brick laid in asphalt mastic; the number of courses of brick to 
be determined by the engineer. 

The requirements in the preceding paragraphs of this section 
likewise shall apply to the roof of the structure within station limits 
and over the tracks passing through the station within said limits. 

The quality of brick used for brick-in-mastic waterproofing 
shall be the best quality common brick, burned hard entirely through, 
regular and uniform in shape. The brick shall be properly dried 
and shall be heated before laying. 

Six (6) plies of waterproofing fabric may be substituted for brick- 
in-asphalt-mastic, if approved by the engineer, and will be paid for as 
provided for fabric waterproofing. 

Asphalt mastic shall contain not less than one-third (i) asphalt, 
the other ingredients to be sand and limestone dust or sand and 
cement. The ingredients are to be in proportions governed by local 
requirements and weather conditions. In melting and mixing the 
mastic its temperature shall not exceed 350 deg. Fahr. (177 deg. 

Any masonry that is found to leak at any time prior to the com- 
pletion of the work and final acceptance thereof shall be cut out and 
the leak stopped, at the sole expense of the contractor. 

Both the coal-tar pitch and the asphalt must be delivered on the 
work in packages that are plainly marked with the manufacturer's 
brand, and indicating the grade and quality of the material. 

The coal-tar pitch shall be straight-run pitch containing not 
less than twenty-five (25) per cent and not more than thirty-two 
(32) per cent of free carbon, which will soften at approximately 70 
deg. Fahr. (21 deg. Cent.), and melt at 120 deg. Fahr. (49 deg. 
Cent.) (by the cube-in-water method) being a grade in which dis- 
tillate oils distilled therefrom shall have a specific gravity of 1.05. 

The asphalt used shall consist of fluxed natural asphalt, or 
asphalt prepared by the careful distillation of asphaltic petroleum, 
subject to the approval of the engineer, but however prepared, it 
shall comply with the following requirements: 


The asphalt shall contain in its refined state not less than ninety- 
five (95) per cent of bitumen soluble in cold carbon disulphide, 
and at least ninety-eight and one-half (98J) per cent of the bitumen 
soluble in cold carbon disulphide shall be soluble in cold carbon 
tetrachloride. The remaining ingredients shall be such as not to 
exert an injurious effect on the work. 

The asphalt shall not flash below 350 deg. Fahr. (177 deg. Cent.) 
when tested in the New York State Closed Oil Tester. When twenty 
(20) grams of the material are heated for five (5) hours at a tempera- 
ture of 325 Fahr. (163 deg. Cent.) in a tin box two and one-half 
(2|) inches in diameter, it shall not lose over three (3) per cent by 
weight, nor shall the penetration at 77 deg. Fahr. (25 deg. Cent.) 
after such heating be less than one-half (J) of the original penetra- 

The consistency shall be determined by the penetration which 
must be between 75 and 100 at 77 deg. Fahr. 

The melting-point of the material shall be between 115 and 135 
deg. Fahr. (46 and 57 deg. Cent.) as determined by the Kraemer 
and Sarnow method. 

Penetrations indicated herein refer to the depth of penetration 
at 77 deg. Fahr. in hundredth centimeters of a No. 2 cambric needle 
weighted to one hundred (100) grams acting for five (5) seconds. 

A briquette of the solid bitumen of cross-section of 1 sq. cm. 
shall have a ductility of not less than twenty (20) cm. at 77 deg. 
Fahr. the material being elongated at the rate of five (5) cm. per 
minute. (Dow molds.) 

All tests herein specified must be conducted according to methods 
approved by the engineer. 

The fabric to be used shall be a woven fabric which shall have 
been treated with coal-tar pitch or asphalt before being brought on 
the work. The fabric * and the material used in its treatment shall 
be approved by the engineer. 

All concrete shall be dry before waterproofing is attached. If, 
in the judgment of the engineer, it is impracticable to have the con- 
crete dry, then there shall be first laid a layer of treated felt of 
approved quality, on the upper surface of which is to be spread the 
first layer of pitch or asphalt. 

Each layer of pitch or asphalt must completely and entirely 
cover the surface on which it is spread without cracks or blow 

The fabric must be rolled out into the pitch or asphalt while the 
* For fabric specifications, see p. 205, 


latter is still hot, and pressed against it so as to insure its being 
completely stuck over its entire surface, great care being taken that 
all joints are well broken by overlapping, and that, unless other- 
wise permitted, the ends of the rolls of the bottom layers are carried 
up on the inside of the layers on the sides, and those of the roof 
down on the outside of the layers on the side so as to secure a full 
lap of at least one (1) foot. Especial care must be taken with this 

When the finishing layer of concrete is laid over or next to the 
waterproofing material, care must be taken not to break, tear or 
injure in any way the outer surface of the pitch or asphalt. 

None but competent men, especially skilled in work of this kind, 
shall be employed to lay the waterproofing. 

Standard Specifications fcr Waterproofing the Philadelphia 
Subways by the Sheet-mastic Brick-in-mastic and Membrane 
Systems. It is the intent of these Specifications * to secure a sub- 
way structure that shall be entirely free from percolation of outside 
water, and the contractor shall do all the work in such manner and 
take such precautions as will secure this result and shall guarantee 
the watertightness of the work for three (3) years. Surfaces shall 
be hard and dry before any waterproofing is attached, and shall 
first be coated with an asphalt paint made from the asphalt herein 
specified diluted with 42 deg. Baume naphtha to the proper con- 
sistency and free of oil. If for any reason it is impracticable to 
have the surface dry, and the engineer so orders, there shall first be 
applied one (1) layer of double-thick roofing felt. 

The waterproofing shall be done as follows: 

The roof shall be waterproofed with two (2) layers of asphalt 
mastic, each one-half (|) inch thick, and protected on top by three 
(3) inches of 1 : 3 : 6 concrete. 

The floor or invert shall be waterproofed with one (1) ply of 
treated fabric in compound and two (2) courses of hard brick, laid 
flat in compound, all laid on a bottom course of 1 : 2 : 4 concrete. 

The side walls shall be waterproofed with one (1) ply of fabric 
treated in compound, against four (4) inches of 1 : 3 : 6 concrete, 
four (4) inches of hollow tile brick or the concrete sheathing of the 
trenches. Against the fabric shall be laid eight and one-half (8) 
inches of brick dipped in compound. The sidewall treatment shall 
extend up to an elevation two (2) feet above ground water line. 

^The asphaltic compound to be used for waterproofing or for the 

* Standard Specifications for Construction of Subway Structure; Dept. of 
City Transit, City of Philadelphia, January, 1917. 


preparation of mastic shall be composed of fluxed refined natural 
lake asphalt, or of asphalt obtained by the distillation of asphaltic 
petroleum. It shall contain at least ninety-five (95) per cent of 
bitumen soluble in carbon disulphide (82), shall have a melting- 
point between 150 and 180 deg. Fahr. by the cube method, and a 
ductility at 40 deg. Fahr. of at least 5 cm., and at 77 deg. Fahr. of 
at least 20 cm. by the Dow method. The mastic shall be prepared 
on the work by thoroughly mixing with the asphaltic compound 
properly graded limestone dust and sand, at a temperature between 
300 and 375 deg. Fahr., so as to make a homogeneous mass. The 
mastic shall be proportioned as follows: 

Soluble bitumen, 12 to 18 per cent as may be found necessary; 
Mineral aggregate passing 200-mesh screen, 25 to 30 per cent; 
Mineral aggregate passing 50-mesh screen, 20 to 30 per cent; 
Mineral aggregate passing 4-mesh and retained on 10-mesh screen, 
20 to 30 per cent. 

Coal-tar pitch, if used for either fabric waterproofing or for the 
" brick in compound " method, shall be straight-run residue from the 
distillation of coal tar. It shall have at least seventy-five (75) per 
cent of bitumen soluble in benzol (CeHe), a melting-point between 
120 and 140 deg. Fahr., and a ductility at 40 deg. Fahr. of at least 
5 cm. Where coal-tar pitch is to be used for waterproofing, the 
sizing paint to be applied to the concrete surfaces in advance of the 
waterproofing shall be raw coal-tar. 

The plans show the invert and sidewalls of the subway structure 
waterproofed, where waterproofing is expected to be necessary, 
by brick laid in compound, but all or part of this work may be 
ordered to be done by using one or more plies of the fabric water- 

The brick used in waterproofing shall be straight and hard, of the 
quality prescribed for " Brick Masonry." The floor and sidewalls 
of the subway structure shall be waterproofed in the following man- 
ner : The excavation for the subway floor shall be made to the proper 
grade and thereon shall be placed a layer of 1 : 2 : 4 concrete, trow- 
eled smooth on top. After this concrete has set and is hard there 
shall be spread on it a complete layer of the hot compound described 
above, as thick as is workable, without cracks or blow holes. On^ 
(1) layer of the treated fabric shall be spread on the coated surface 
while the compound is still hot and be pressed flat against its entire 
surface with an electrically heated iron, so that it shall firmly adhere 
to the surface without bubbles or air spaces. The exposed surface 


of the fabric shall then be completely coated with hot compound. 
On this surface two (2) courses of brick shall be laid flat. The 
brick shall have previously been dried, and while warm shall be 
dipped in compound and laid on a bed of the compound on the 
coated fabric. The compound shall completely fill the spaces between 
the bricks and the top course finished off with a thin layer of the 
compound. The waterproofing shall be continuous and extend 
around all projections of the invert and sidewalls of the subway. 
Upon the coated brick laid on the invert there shall be built at the 
sides the waterproofing for the sidewalls by placing one (1) ply 
of treated fabric as herein described against the concrete sheeting, 
or against four (4) inches 1:3:6 concrete or hollow-tile masonry. 
Against this coated layer of fabric there shall be laid eight and 
one-half (8J) inches of dried warm brick, dipped in hot compound 
and laid in compound while hot. The bricks shall break joint, 
and the spaces between the bricks be completely filled with com- 

The fabric shall be an approved woven cotton cloth, weighing 
before treatment, not less than 5 ounces per square yard-, with at 
least thirty (30) threads per inch. It shall be thoroughly saturated 
with the asphaltic compound described above before laying, shall 
have no admixture or coating of mineral or other matter, and shall 
weigh after saturation not less than fourteen (14) ounces per square 
yard. The term " ply " shall be understood to mean a layer of woven 
cotton fabric saturated with compound before laying, with a layer 
of compound on each side of it applied in laying. A complete layer 
of hot compound as thick as is workable shall be evenly spread on 
the surface to be waterproofed, without cracks or blow holes. The 
fabric shall then be spread on the coated surface while the compound 
is still hot, and be pressed flat against its entire surface with an 
electrically heated iron, so that it shall firmly adhere to the surface 
without bubbles or air spaces. The exposed surface of the fabric 
shall then be completely coated with the hot compound. Where 
steel or concrete sheathing is placed at the waterproofing line, the 
waterproofing from the floor line to two (2) feet above ground water 
line shall be applied against the sheathing. 

Asphaltic material shall be delivered to the work in original pack- 
ages, marked with the manufacturer's name and brand, and indicating 
the grade and quality of the material. 

Where holes or void spaces are to be filled or built in after the 
removal of temporary posts, shores or braces, the utmost care shall 
be taken to bond the new concrete or other material to the prior 


work, and to make the placing of patches of waterproofing continu- 
ous and watertight. The contractor shall execute his work in such 
a manner as to eliminate as far as possible such patchwork. 

Every care shall be exercised not to puncture or otherwise injure 
the waterproofing after it is in place and when applying the protect- 
ing masonry. If any leaks are found before the completion of the 
work, the defective portions shall be cut out and efficiently 

Only competent men skilled in this particular class of work will 
be 'permitted to do the waterproofing. The contractor will be 
required to guarantee the efficiency of waterproofing by the render- 
ing of watertight structure during the three-year period for' main- 

Waterproofing shall not be done when exposed to wet weather, 
nor to a temperature below 40 deg. Fahr., and it shall be applied 
only when the surface to be treated is perfectly dry. 

Remarks. The above specifications refer to the method of deter- 
mining the melting-point of bitumen as the "cube-method"; 
there are two distinct methods for finding the melting point of bitu- 
mens that fall under this head; one is the " cube-in-air," the other 
is the " cube-in- water " method, the latter giving lower results for 
the same bitumen and is not as suitable for asphalt. It would be 
better if the exact method preferred were stated in the specification. 

The specifications further call for bricks to be imbedded not in 
the usual mastic but in pure asphalt. A good mastic is stronger than 
its constituent asphalt. Mastic is also more substantial than pure 
asphalt and cheaper as well. For these reasons alone, brick-in- 
mastic is preferable to brick-in-asphalt. 

The specifications permit the use of coal-tar pitch with a melting- 
point between 120 and 140 deg. Fahr. For waterproofing by the 
membrane system, coal-tar pitch of this melting-point has been very 
successfully used on underground work. But mastic made of coal- 
tar pitch with a melting-point above 120 deg. Fahr. is not suitable 
for subsurface waterproofing in this climate. On the other hand, 
if the pitch is intended for use with bricks without incorporating 
any foreign ingredients it will lack " body " and the bricks will soon 
rest one upon the other. 

One test requirement of coal-tar pitch in the specification is 
that it should have a ductility of 5 cm. at 40 deg. Fahr. A straight- 
run coal-tar pitch of the melting-point called for, has practically 
no ductility at this temperature. 

The specifications also call for a woven cotton fabric of a certain 


weight, raw and treated; as weight has little bearing on the strength 
of the material it would seem a better policy to specify a tensile 
strength. A woven cotton fabric whose ratio of tensile strength in 
the warp and woof approaches unity, is best for the purpose of water- 
proofing. The tensile strength in the warp should not be less than 
60 pounds per lineal inch. 

Specifications fcr Waterproofing Tunnels on the Pennsylvania 
Railroad.* It is intended that the interior of waterproof structures 
shall be permanently free from moisture or discoloration due to the 
percolation of water or other liquids from outside sources. This 
end shall be attained by means of a continuous flexible waterproof 
sheet surrounding the exterior of the structures. 

Pitch used shall be straight-run coal-tar pitch, which shall soften 
at 60 deg. Fahr. (15.5 deg. Cent.) and melt at 100 deg. Fahr. (36 
deg. Cent.) : being a grade in which distillate oils distilled therefrom 
shall have a specific gravity of 1.05. 

The felt shall be (trade name and manufacturer giceri) or be equally 
satisfactory to the engineers. 

Coal-tar pitch, when applied, shall be at a temperature of not 
less than two hundred fifty (250) deg. Fahr. (121 deg. Cent.). The 
pitch shall be mopped on the surface of the masonry to a uniform 
thickness of not less than -^ inch. Each layer of pitch must com- 
pletely cover the surface on which it is spread without cracks or 
blowholes. The felt must be rolled out into the pitch while the latter 
is still hot and pressed against it so as to insure its being completely 
stuck to the pitch over its entire surface. Great care must be taken 
that all joints in the felt are well-broken, and that the ends of the 
rolls of the bottom layer are carried up on the inside of the layers 
on the sides, and those of the roof down on the outside of the layers 
on the sides, so as to secure the full laps herein specified. 

Waterproofing must be protected against injury at all times 
to the satisfaction of the engineers. 

Any waterproofed structure that is found to leak at any time prior 
to the completion of this contract shall be made tight by the con- 
tractor in a manner satisfactory to the engineers. 

Waterproofing shall consist of six (6) layers of felt and seven (7) 
layers of pitch alternating, each strip of felt to lap not less than one 
(1) foot upon the previously laid strip and each section of water- 
proof sheet shall lap at least one (1) foot with the adjoining section. 

Waterproofing will be measured by the square or one hundred 
(100) superficial feet and paid for accordingly. 

* Transactions, American Society of Civil Engineers, Vol. 69, p. 211, 


Remarks. The above specification would have increased merit 
did it not leave the acceptance of materials, the protection of the 
waterproofing, etc., to the discretion of the field engineer. The 
engineer's judgment is undoubtedly sound, and his intentions 
undoubtedly good, but his experience may be very limited in regard 
to waterproofing and too often he considers waterproofing not a 
very important item of the work. The properties of waterproofing 
materials are not a matter of common knowledge as the properties 
of other construction materials are, neither are systems of water- 
proofing as standardized as other branches of construction. It seems 
therefore that the specification writer would be amply justified in 
receiving the best advice and information regarding these matters 
and incorporating them in the specification as a help and guidance 
to the field engineer. The melting-point of the pitch called for 
in the specifications is indefinite since the method of determining 
same is not given. 

Specifications for Mixing and Placing Grout for Waterproofing 
Tunnels.* Under this item shall be included the transportation of 
grouting materials, the operation of grouting plant and all other 
labor, not specifically included in other items, connected with the 
mixing and placing of all grout in any part of the work included in 
this contract, whether such placing is by pouring, by forcing through 
pipes or by impregnation by use of the grouting pad, under any 
required pressure not exceeding 300 pounds per square inch. The 
work to be done under this item shall include all requisite precau- 
tions to prevent the setting of grout which may escape upon the 
exposed surfaces of the masonry, and all measures necessary for the 
removal of grout which may have adhered to such surfaces and for 
restoring such surfaces to their original condition. 

Grouting will be done to fill all voids in dry packing or elsewhere 
over the tunnel arch, to close cracks, seams and fissures in the 
rock about the tunnel or shafts, to increase the imperviousness of the 
masonry lining, to insure a watertight contact with, and the com- 
plete protection of, steel work embedded in the masonry, and for 
other purposes as required. 

Except where it may be ordered to reduce leakage in wet ground, 
or to increase the stability of shattered, moving or unstable ground, 
or in connection with sections of masonry lining built to control such 
leakage or to support such heavy ground, grouting under pressure 

* The above specifications are extracted from the general specifications 
issued by the Board of Water Supply of the City of New York in 1910, for the 
construction of a portion of the City Tunnel of the Catskill Aqueduct, in the 
Boroughs of Bronx and Manhattan. 


will not generally be ordered under this item, in any place, except 
in less deep portions of shafts where the external water-pressure is 
comparatively light, until three months after placing the complete 
ring of lining masonry at that place. Grouting shall be kept as 
nearly up with the concreting as the three months' interval permits. 

Grout shall be mixed of a consistence suitable to the work in hand, 
in general as thick as can with certainty be made to completely fill 
the voids. It is the intention to make grout which is to be forced 
into pipes not less rich than 1| parts, by weight, of sand or stone 
dust to one part of cement. All ingredients shall be entirely free 
from lumps when put into the mixer. When the grouting of any 
seam, void, or section of dry packing has begun, it shall, unless other- 
wise expressly ordered, be prosecuted continuously until completed, 
without any intermission long enough to allow the grout to take an 
initial set. In order to insure a complete filling of voids, as in dry 
packing over the tunnel arch, and to avoid occluding air in the 
interstices of such dry packing, the grout shall be delivered uni- 
formly and steadily, not in violent spurts or blasts. 

By a sufficient number and suitable spacing of grout pipes, by 
the simultaneous use of a sufficient number of grouting machines, 
and by changing of connections as required, grouting of dry-packed 
spaces or of other spaces over the tunnel arch shall be so done, except 
in cases where the engineer deems it impracticable, that all voids 
can be filled without requiring any grout to travel more than 25 feet 
after leaving the grout pipe; and this distance shall be reduced as 
required. Grouting of any section of tunnel shall begin at the bot- 
tom and proceed uniformly, upward unless some other order of grout- 
ing is directed. In grouting spaces over the tunnel arch through 
pipes having their upper ends at different elevations, grouting shall 
invariably begin at the lowest pipes, and no connection shall be made 
to pipes higher up until the grout has completely filled the space 
below such higher pipes, as shown by the grout flowing out of them. 
These spaces, whether dry-packed or not, are to be divided into 
sections of a length not exceeding 50 feet by masonry cut-off walls 
built across them and tight against the tunnel roof. 

Wherever 50-foot sections over the tunnel arch, or other large 
voids, are being grouted, such number of grouting machines as may 
be ordered, generally not less than two, shall be concentrated on 
each such section or void. Grouting will be considered to be com- 
pleted, in each case, when no more grout can be forced into the seam, 
void or dry-packed space under the required pressure up to 300 pounds 
per square inch. 


Regrouting of sections of shaft or tunnel once grouted shall be 
done if and as required. Water may be ordered forced into pipes 
for the purpose of opening channels in grout previously placed, or 
for other purposes, in which case any required pressure up to 300 
pounds per square inch shall be applied. 

Under the item of sand for grout the contractor shall furnish at 
some central point natural or artificial sand of the quality below 
specified, for grout. The specifications for sand for concrete shall 
apply equally to the sand furnished hereunder, except that the sand 
for grout is to be of such fineness that 100 per cent will pass a sieve 
having sixty-four openings per square inch, and 45 per cent will 
pass a sieve having 1600 openings per square inch, the wires of the 
sieves being respectively, 0.035 and 0.013 inch in diameter. To 
obtain this degree of fineness it may be necessary to roll coarser 
natural sand or stone screenings. 

For convenience in handling and measuring into the grouting 
machine the sand shall, unless otherwise specifilly permitted, be put 
up in strong sacks each containing a standard weight of sand con- 
taining not more than an ordinary degree of moisture (3 to 5 per cent) . 
The quantity to be paid for under this item shall be the number of 
toni of sand actually mixed in grouting machines, in accordance 
with order, for grout placed as above specified. 

The quantity to be estimated for payment under this term shall 
be the number of cubic yards of liquid grout actually mixed in accord- 
ance with orders. The volume will be computed from the quantities 
of dry materials, on the assumption that the grout is mixed, in each 
case, of the consistency established as a standard for that case. The 
contractor shall keep an accurate tally of the quantities of materials 
used in grout each day, in each heading or shaft, and shall report 
such quantities to the engineer not later than the following day. 
From time to time as the engineer deems necessary, tests will be 
made to determine the relation between the volume of grout and the 
quantities of the dry materials, and the estimates will be based upon 
these tests. 

If in the opinion of the engineer there is avoidable waste of grout 
into the interior of shaft or tunnel, the volume of grout unnecessarily 
wasted, as estimated by him, shall be deducted from the quantity 
to be paid for. 

Remarks. The process of grouting has been resorted to in several 
other places throughout the country for sinking shafts in coal mines 
and salt mines, for waterproofing linings in waterworks tunnels and 
inverted siphons, for solidifying rock foundations for dams and other 


structures; but nowhere has this process been used so extensively, 
so exhaustively studied and experimented with, and so successfully 
prosecuted as on the aqueduct grouted under the above specifica- 
tions. A complete description of the grouting process, the grouting 
equipment, a history of grouting on various works, and a great 
deal of other valuable information will be found in the Proceedings 
of the Brooklyn Engineers' Club, Vol. XIX, page 131, 1915, Brooklyn, 
New York. 

Specification for Waterproofing Pneumatic Caisson.* The floors 
of shaft caissons (see Fig. Ill) shall be waterproofed with six (6) 
plies of fabric f and seven (7) layers of coal-tar pitch. In order to 
avoid fumes from hot pitch in compressed air, the fabric shall be 
made up in normal air in pieces or mats of three plies with coal-tar 
pitch binder (melting-point 120 deg. Fahr. (4Q deg. Cent.) by the 
(cube-in- water method), each thickness bonding four (4) inches on 
edges. These triple layers shall be in pieces of convenient size as 
required by the engineer and shall be passed through the airlock 
intD the air chamber of the caisson. The earth or rock in the bot- 
tom of the chamber shall be covered with a layer of concrete, about 
six (6) inches in thickness, troweled smooth with a coating of mortar 
containing equal parts, by volume, of cement and sand. Upon this 
coating shall be spread a layer, not less than one-sixteenth (^) 
inch in thickness of soft pitch which will soften at 32 deg. Fahr. 
(0 deg. Cent.) and melt at about 60 deg. Fahr. (15.5 deg. Cent.) 
so that it can be spread without heating. Upon this shall be spread 
a triple layer of fabric with lap of twelve (12) inches on longitudinal 
joints giving four-ply along the laps, and with lap cf eighteen (18) 
inches on transverse joints. All laps shall be laid in soft coal-tar 
pitch. The three-ply layer shall be covered with a layer of one- 
sixteenth (r-) inch of soft pitch, and another three-ply layer of 
fabric, laid in the manner described, and so as to break joints with 
the first layer, followed by a final coating of soft pitch. Upon this 
shall be laid one course of brick, on the flat, in mortar containing 
equal volumes of cement and sand. Care shall be taken to secure the 
best obtainable bond between the waterproofing and the metal work 
of the caissons. Other parts of the railroad which are not lined with 
cast iron and which are required to be waterproofed in compressed 
air, may be required to be waterproofed in the manner described 

* Public Service Commission Specifications for New York Rapid Transit 
R. R. Route 48, Section 31 (William and Clark St. Tunnel), April, 1914. 
t For quality of fabric here referred to, see p. 265, 



Before placing the first course of concrete in the floors of shaft 
caissons, under drains shall be laid to a central sump as directed by 
the engineer, and all tendency to uplift of the concrete floor shall 

__L__^ ^___-____^_^_-_ t_^HT g*:j.-.. 

be prevented by continuous pumping for a period of ten (10) days 
after the completion of the concrete floor above the waterproofing. 
The arrangement for pumping shall be such as to prevent drawing 
sand from beneath the floor. After the expiration of said period of 


ten (10) days, pumping from the sump shall be suspended and the 
sump capped and made watertight and the air pressure gradually 
reduced to one-half the pressure due to the hydrostatic head. If 
defects in the waterproofing appear, the contractor shall repair the 
defects. After a satisfactory test, the concrete filling in the sump 
shall be completed. 

The utmost precautions in regard to fire in the caisson chamber 
shall be taken at all times while the waterproofing layers of fabric 
and pitch are exposed, and no lighted candles or matches will be 


Specifications for Waterproofing Concrete Structures on the 
Chicago, Milwaukee & St. Paul Railway. The necessary pro- 
vision- for drainage and expansion must be made in designing the 
structure. The waterproofing should never be compelled to resist 
hydrostatic pressure, and the membrane should always be protected 
by a layer of concrete. 

Fill all openings and pockets in the concrete, except expansion 
joints, with cement mortar, and round off all sharp corners. Wher- 
ever waterproofing stops on a vertical parapet, the end should be 
flashed into a groove in the concrete. 

Thoroughly clean and dry the concrete surface, using wire 
brushes and being careful to remove all the laitance. If necessary, 
use hot sand to dry the concrete. Apply a coat of gasoline to the 
clean dry surface and follow with a coat of cold primer spreading 
the primer evenly with a brush. Omit the primer where tar paper 
is to be placed and over expansion joints. 

After the primer coat has completely dried, apply a coat of pure 
hot asphalt, and mop until the layer has a thickness of f inch. 
While the asphalt is still hot, begin laying the burlap. Lay the 
first strip of burlap transverse to the drainage at the lowest point. 
Lay the strips shingle fashion, as for tar and gravel roofs, and parallel 
to the first strip working up to the summit and exposing one-third 
of each width of burlap to the weather. Press each strip firmly 
into the asphalt, then mop well with pure melted asphalt taking 
care to thoroughly saturate the burlap and to fill all cracks and blow 
holes. Lap the joints in the strips 6 inches. On this three-ply 
layer of burlap spread a continuous layer of hot asphalt mopping 
well until a layer of J inch is obtained. See (/) Fig. 112. 



After the |-inch layer of asphalt on top of the burlap has become 
cold spread a f-inch layer of concrete evenly over the surface. 
Then press a layer of expanded metal into the concrete and cover the 
metal with a layer of concrete | inch thick making the total thick- 
ness of the concrete If inch thick and trowel the concrete smooth. 



Concrete^ Expanded Metal > 3 Layers of Burlap 


irface of Waterproofing to conform 

to Surf ace or Base 

Coat of Primer Asphalt 

Expanded Metal 


3 Layers of Burlap-. 


2 Layers ofjlar Paper ) _ 



FIG. 112. Standard Methods of Waterproofing Bridge Floors, C. M. & St. P. Ry. 

Protect the concrete from the sun for twenty-four hours after laying. 
The joints in the expanded metal should be lapped 6 inches. (See 
(d) Fig. 112). 

After the work has been brought up to the desired point from both 
sides, interlap, in order, the strips which reach across the joint, 
mopping asphalt between burlap surfaces. Place a strip of burlap 


along the joint for a closing strip; complete by laying the upper 
| inch of asphalt as before described. See (g) Fig. 112. 

If possible the waterproofing should be laid in one run the full 
width transverse to the drain slope of the surface to be waterproofed. 
The ends of the burlap strip should be flashed into recesses in the 
walls, curbs or parapets as shown &t (e). Where longitudinal 
joints are necessary cut the burlap long enough to extend 12 inches 
beyond the primed and asphalted surface of the concrete and use 
care as the strips are laid that the 12-inch strip is kept free from 
asphalt. When the succeeding section is to be waterproofed, fold 
back the projecting strips of burlap over the completed waterproofing 
and bring the new up against the completed portion of the water- 
proofing, interlapping the projecting ends of the burlap with the new 
burlap as the work progresses; this is shown at (/). On concrete 
trestle or subway slabs longitudinal joints in the waterproofing 
should preferably be on the center line of the slabs. If it is neces- 
sary to place joints in the waterproofing over joints in the slabs 
special care should be taken. 

Lay two continuous strips of tar paper 36 inches wide over the 
expansion joint, being careful to see that no asphalt gets between or 
under the two strips of tar paper. Then mop the top strip with hot 
asphalt and carry the waterproofing over the top of the paper 
the same as if no joint existed. See (6) and (h). 

The burlap is to be a treated, 8-ounce, open-mesh burlap fur- 
nished in widths of 36 to 42 inches. 

The concrete is to be one part Portland cement, two parts tor- 
pedo sand and three parts stone or gravel that will pass a J-inch 

The mortar is to be one part Portland cement and two parts 
washed torpedo sand. 

The primer is made by pouring hot asphalt in 80 deg. Baume" 
gasoline until mixture will spread readily with a brush. 

Pure asphalt conforming to accepted specifications is to be used. 
Before using the asphalt heat it in a suitable kettle to a temperature 
not exceeding 450 deg. Fahr. (232 deg. Cent.). The temperature 
is to be taken with a thermometer. Asphalt heated above 450 deg. 
Fahr. or giving off yellow fumes is to be discarded as overheated. 

The expended metal is to be equivalent to (manufacturer's name 
stated) " 2J-inch No. 16 Regular " expanded metal. The tar paper 
will be furnished in rolls 36 inches wide. 

Remarks. In describing the color of fumes coming from the sur- 
face of overheated asphalt as being yellow, the author desires to 


correct this general misconception and state that the fumes of burned 
asphalt are bluish black and the fumes of coal-tar pitch are yellow 
with a greenish tinge. 

Specifications for Waterproofing Concrete Structures on the 
Chicago, Burlington & Quincy Railroad. The waterproofing shall 
consist of a mat of four ply of burlap and one ply of felt thoroughly 
saturated and bonded together with waterproofing asphalt and 
covered with 1 inch of sand-and-asphalt mastic. No waterproofing 
shall be done when the temperature is less than 60 deg. Fahr. 
(15.5 deg. Cent.). 

The surface of the concrete shall be smooth, clean and dry. 
Upon this surface there shall first be applied, with brushes, a coat 
of priming paint, which shall be thin enough to penetrate the con- 
crete and form an anchorage for the waterproofing. 

After this priming coat has dried, a heavy coat of waterproofing 
asphalt, heated to a temperature of 400 deg. Fahr. (204 deg. Cent.), 
shall be applied with mops, the width of the burlap, and while 
this is still hot a layer of burlap shall be bedded in it. The burlap 
shall be laid just behind the mopping and swept with a broom, and 
must be free from folds and pockets. The surface of this burlap 
shall be heavily mopped with waterproofing asphalt, and three 
more ply laid in the same manner, making a four-ply burlap mat all 
thoroughly saturated and bonded together. The top of the burlap 
mat shall be heavily mopped and one thickness of felt saturated 
with asphalt laid on it, the edges lapped at least 3 inches, and sealed 
with asphalt. The top of this felt shall also be mopped with water- 
proofing asphalt. This shall then be covered with 1 inch of asphalt 
mastic laid in one layer, the mastic to be composed of one part of 
waterproofing asphalt and four parts of fine gravel graded from 
J inch to fine sand, the top leveled off with wooden floats and 
mopped with a heavy coat of asphalt. 

At all the expansion joints in the concrete a fold, to allow for the 
expansion of the structure, shall be formed by laying the burlap and 
felt over a 1-inch pipe and removing the pipe as the mat is being 

Where the work is stopped before being completed, at least 3 feet 
of burlap at the end and half the width of the burlap at the side shall 
be left exposed to form a splice. Special care shall be taken to seal 
the waterproofing at the sides and ends of the bridge. The burlap 
and mastic shall be carried up the parapet walls at the sides and the 
ends concreted in a recess in the walls so that no water can enter. 
The burlap shall be carried down over the back walls at the ends of 


the bridge to cover all construction joints and shall run into a line 
of tile to facilitate the escape of the water. 

The burlap shall be 8-ounce, open-mesh, high-grade burlap satu- 
rated with an asphalt meeting the specifications for waterproofing 
asphalt. It shall come in rolls which shall be placed on end for ship- 
ment and storage, and shall not stick together in the roll. The felt 
shall be a good quality wool felt, saturated and coated with an 
asphalt meeting the specifications for waterproofing asphalt. It 
shall come in rolls, which shall be placed on end for shipment and stor- 
age, and shall not stick together in the roll. It shall not weigh less 
than 15 pounds per 100 square feet. The primer shall be an asphaltic 
compound of approved quality and capable of adhering firmly to the 

The waterproofing asphalt shall meet the following requirements: 
(1) The specific gravity of the asphalt desired shall be greater than 
0.95 at 77 deg. Fahr. (25 deg. Cent.). (2) The flowing-point shall 
not be less than 130 deg. Fahr. (54.5 deg. Cent.) nor more than 
140 deg. Fahr. (60 deg. Cent.). (3) The flash point shall not be 
lower than 450 deg. Fahr. (232 deg. Cent.). (4) The penetration 
at 80 deg. Fahr. (27 deg. Cent.) for a period of thirty seconds shall 
be at least 15 mm. and must not exceed 20 mm. This penetration 
to be measured with a Vicat needle weighing 300 grams, one end 
being 1 mm. in diameter for a distance of 6 cm. (5) When heated 
to a temperature of 325 deg. Fahr. (163 deg. Cent.) for seven hours 
the loss in weight shall not exceed 2 per cent and the penetration 
of the residue at 80 deg. Fahr. and for the period of thirty seconds 
using the same instrument as described above shall not be reduced 
more than 50 per cent. (6) The total soluble in carbon disulphide 
shall not be less than 99 per cent. (7) The total soluble in 88 deg. 
naphtha shall not be less than 70 per cent. (8) The total inorganic 
matter or ash shall not exceed 1 per cent. (9) Cold test, (a) A 
cube of asphalt 1 inch on edge shall be soft and malleable at a tem- 
perature of deg. Fahr. ( 18 deg. Cent.). (6) A film of the asphalt 
having a thickness not less than ^ inch shall be so pliable at deg. 
Fahr. that it can be bent in a radius of 2 inches. The total time 
consumed in the bending of this film shall not exceed three seconds. 
(10) The asphalt shall not be affected by any of the. following solu- 
tions, after being immersed in them for a period of three days: (a) 
A 25 per cent solution of sulphuric acid; (b) a 25 per cent solution 
of hydrochloric acid; (c) a 20 per cent solution of ammonia. 

Remarks. The above specification differs from the previous one 
mainly in that it specifies a 1-inch thickness of asphalt mastic as a 


protective coat over the membrane. This is good practice but it 
requires very careful selection of materials, and good workmanship 
in its preparation and application for the best results. In describing 
the testing of the waterproofing asphalt, no mention is made of the 
method of determining the flowing-point. Besides, from the tem- 
perature given, it is evident that the melting-point is meant, and not 
the flowing-point, because the flowing-point is only a comparative 

Limiting the work of waterproofing to an atmospheric tempera- 
ture of 60 deg. Fahr. is at least 20 deg. too high and therefore too 
restrictive a clause. A surface-coating of sand on top of the mastic 
is an advisable requirement, as this tends to prevent abrasion of the 
surface by the ballast. 

Specifications for Waterproofing Solid-floor Railroad Bridges, f 
The depth of steel or concrete construction shall be such as to allow 
a sufficient distance from top of rail to top of steel or concrete 
floor for proper waterproofing and protection from the cutting action 
of the ballast. Under ordinary conditions, a depth of from 3.5 to 
4.0 feet from top of rail to clearance line below is sufficient. 

Provision shall be made for grades of at least 1 per cent on the 
floor of the bridge to remove water promptly. Where this cannot 
be done in the steelwork, cement mortar, with a minimum thick- 
ness of 2J inches, shall be placed so as to drain the water to the inlets. 

Cast-iron inlets shall be set at proper places in the floor and 
provided with movable top grates. The down-spout from each 
inlet shall be provided with a trap and cleanout, which shall be 
accessible from below the bridge. The down-spout shall be of 
wrought iron, and connected to a sewer or arranged according to local 

On top of the prepared surface of the concrete shall be placed 
either of the following: 

1. One or more thicknesses of felt or fabric, of quality and 
applied as specified hereafter, together with proper protection. 

2. Asphalt mastic at least 1J inches in thickness, of quality and 
applied as specified hereafter. 

Felt, Burlap or Fabric. When waterproofing material of this 
kind is to be used, either of the following types shall be adopted: 

1. From four to six layers of felt. 

2. One middle layer of treated burlap, with four layers of felt. 

3. One layer of felt, two layers of burlap, and two layers of felt. 

* See Chapter VII on Flow-point Test. 

f Proceedings, American Society of Civil Engineers, Vol. 40, No. 10, 


4. One middle layer of treated burlap, and two layers of asbestos 

5. Either one or two layers of treated cotton-drill fabric. 

After the completion of the felt or fabric waterproofing, the entire 
surface shall be covered and protected by one of the following 
methods : 

1. Straight, hard-burned brick laid flat, with joints filled either 
with waterproofing compound or cement grout. (Waterproofing 
compound should only be used as a filler on flat or nearly flat 

2. A layer of concrete from 2 to 2| inches thick with wire rein- 

3. A layer of about 1J inches of asphalt mastic used only on top 
of asbestos felt. 

On top of the protection coat, and outside the line of the ties, 
a line of half-round cast-iron pipe, 6 inches in diameter, and per- 
forated frequently, shall be placed to collect the water and convey 
it to the inlets. 

All openings in the steelwork shall be thoroughly closed, either 
by calking with burlap dipped in hot asphalt, or by the use of sheet 
metal sufficient to maintain the concrete base before applying the 
burlap and asphalt. 

Wherever called for by the plans, the decks of the bridges shall 
be protected with 1:3:5 concrete, with f-inch stone or gravel, 
mixed as specified hereafter, finished with a 1 : 2 mix of cement 
mortar, \ inch thick, troweled to a smooth surface on top. This con- 
crete shall be allowed to dry thoroughly so as to prevent the forma- 
tion of steam when the hot waterproofing materials are applied. 

All vertical or sloping surfaces of concrete or steel shall be cleaned 
of dust, dirt, loose particles, paint, and grease. The use of a hand- 
bellows is recommended for cleaning loose dust and dirt from the 
surfaces. For cleaning paint and grease from the steel and freshen- 
ing the surfaces of asphalt, where a junction of old and new is to be 
made, or where a pocket of pure asphalt is used against the girders 
and the felt or mastic, gasoline shall be used, either by swabbing 
the surface with it, or by pouring a small quantity over the surface 
to be cleaned and setting fire to it. The use of a blow-lamp is 
also recommended. 

These surfaces shall then be painted with two coats of approved 
asphalt, diluted with gasoline. The materials of the first coat shall 
be proportioned so as to give a brownish tint. The second coat shall 
have a larger quantity of asphalt. 


Both coats of paint shall be thoroughly applied and worked into 
the surfaces, so as to give a uniform coating of the asphalt. 

Paint shall not be applied to damp concrete or steel. The paint- 
ing shall be done immediately in advance of the application of the 
waterproofing materials and before dust has had time to collect. 

If the concrete is damp before the waterproofing is applied, the 
surface shall be first covered with a 2-inch layer of hot sand and 
allowed to stand for from one to two hours, after which the sand 
shall be swept back, uncovering sufficient surface to begin work, 
and the operation repeated over a new surface. 

All concrete shall be of such consistency that when dumped in 
place it shall not require much tamping, and shall be laid with a 
view to be an aid to the watertightness of the structure, and not 
merely a support for the waterproofing materials. All showing 
surfaces shall be troweled to a smooth, hard surface. 

In cases where concrete haunching against girders is called for by 
the plans, forms shall be used, and the concrete shall be of a wet 

On the prepared surface, apply the specified number of layers of 
approved saturated and coated felt (with a finished surface) weighing 
about 14 pounds per 100 square feet. 

The bids shall be based on the use of the type of felt specified 
in the above paragraph, but additional alternate bids will be con- 
sidered, based on felts or fabrics other than these, which may be 
approved by the chief engineer. In the event of such alternate 
bids being made, the bidders shall present with them sufficient data 
as to the methods of manufacture, quality of materials, and references 
to places where such felts or fabrics have been used, giving dates of 

All materials shall be delivered on the work in their original 
packages, and properly branded. 

The asphalt used shall consist of fluxed natural asphalt, or asphalt 
prepared by the careful distillation of asphaltic petroleum. 

It shall contain, in its refined state, not less than 98 per cent of 
bitumen soluble in cold carbon-disulphide. The remaining ingre- 
dients shall be such as not to exert an injurious effect on the 

When 20 grams are heated for five hours at a temperature of 
325 deg. Fahr. (163 deg. Cent.) in a tin box 2J inches in diameter, 
it shall not lose more than 2 per cent by weight, nor shall the pene- 
tration at 77 deg. Fahr. (25 deg. Cent.) after such heating, be less 
than one-half of the original penetration. The consistency shall 


be determined by the penetration, which must be between .75 and 
1.00 cm. at 77 deg. Fahr. 

The penetration indicated herein refers to the depth of penetra- 
tion, in hundredths of a centimeter, of a No. 2 cambric needle, 
weighted to 100 grams, at 77 deg. Fahr., acting for five seconds. 

The melting-point shall be between 150 deg. and 190 deg. Fahr. 
(66 and 88 deg. Cent.). 

A briquette of the solid bitumen, having a cross-section of 1 
sq. cm., shall show ductility at 40 deg. Fahr. (4 deg. Cent.) and at a 
temperature of 77 deg. Fahr. shall show a ductility of not less than 
20 cm., the material being elongated at the rate of 5 cm. per min. 
(Dow molds.) 

All flashing and reinforcing around inlets and other places speci- 
fied shall be carefully executed. 

Waterproofing shall not be done in wet weather, or at a tempera- 
ture below 32 deg. Fahr., without special orders from the chief 
engineer. The felt shall be laid shingle fashion, the first two layers 
longitudinally and the last three transversely to the center line of 
the bridge, where five layers are called for, and as specified in detail 
in other cases, and shall be carried up the haunching and made secure 
against the girder in a satisfactory manner. The flashing against 
vertical or inclined surfaces shall be in accordance with the direc- 
tions of the chief engineer, if not indicated on the plans. The first 
layer of felt shall not be cemented to the floor of a steel bridge, 
except around the drain outlets. On an arch bridge, the first layer 
shall be cemented to the top of the arch. At no point shall there be 
less than the specified number of thicknesses. 

As the hot asphalt is spread, the felt shall be immediately rolled 
into it, rubbed and pressed over the surface so as to eliminate air 
bubbles and insure thorough sticking. One mopful of the asphalt 
shall not be spread over more than 1 square yard of surface at one 
mopping. Not less than 2.5 to 3 gallons of asphalt shall be used on 
100 square feet of a single layer of felt. The top layer shall also be 
mopped and the work done so that the layers shall be one compact 

The finish of the waterproofing against the girders or concrete 
shall be made with a pocket of pure elastic asphalt of the quality 
specified above, except that the melting-point shall be between 140 
and 180 deg. Fahr. (69 and 82 deg. Cent.), the ductility at 40 deg. 
Fahr. shall be at least 3 cm. and the adhesive qualities shall be 
satisfactory to the chief engineer. The surfaces with which this 
material comes in contact shall be dry, absolutely free from dust or 


grease, and, previous to its application, shall be covered with a 
thin paint made by dissolving the asphalt in gasoline. 

Particular care shall be taken to make a tight joint around gus- 
sets, stiffeners, and the ends of girders. 

Care shall be taken to prevent injury in any way to the waterproof- 
ing by the passing of men or wheelbarrows over it, or by throwing 
any foreign materials on it. 

After the waterproofing course has been completed, the horizontal 
surfaces shall be protected by a course of straight, hard-burned and 
dense brick, laid flat in a bed of 1 to 3 cement mortar, with full 
joints. There shall be not less than \ inch of mortar between the 
felt and the bricks. The brick shall not increase in weight more 
than 10 per cent when immersed in water for seven hours. 

The haunching, and about 18 inches in width of the horizontal 
surface adjacent to the haunching, shall be protected by about 
2J inches of 1 : 3 : 5 concrete, reinforced with No. 8 or No. 10 wire 
cloth, electrically welded. 

Every care shall be taken to insure satisfactory and thoroughly 
watertight joints between the main layer of waterproofing and the 
girders; and special attention shall be given to stiffeners, gussets, 
etc. The waterproofing shall also be carried down over the back 
walls to below the elevation of the bridge seat, or as directed. 

Rolls of felt shall be stored on end, and not laid on their sides. 

Waterproofing shall be done only by experienced and expert 

Application of Waterproofing. Wherever called for, the decks 
of bridges shall be waterproofed with natural rock asphalt mastic, 
as specified below. 

The concrete, prepared as specified heretofore, shall be water- 
proofed with asphalt mastic equal in quality, as to ingredients used 
and resistance to water, to the following specifications: 

Sicilian rock asphalt mastic 60 parts 

Clean, sharp, graded grit and sand to pass a sieve of 8 

meshes per inch 30 parts 

Asphalt as specified above for membrane binder 10 parts 

These proportions shall be varied when required by special con- 
ditions on the work. 

The mixture shall be made at the site of the work, shall be heated 
to a temperature of from 250 to 300 deg. Fahr. (121 to 149 deg. Cent.) 
and shall be stirred until all the ingredients are thoroughly incor- 
porated. It shall then be spread and thoroughly worked, to free 


it from voids, and shall be ironed to a smooth surface with smoothing 
irons, if so directed. All mastic shall be applied in two coats, making 
the required thickness. The two coats shall break joints, and the 
mastic shall be distributed evenly. Where the thickness of the 
concrete plus mastic is less than 2J inches, the full thickness shall be 
made up of asphalt mastic. 

Pockets of asphalt shall be placed against all metal, and mastic 
along girders, around stiffeners, gussets, etc., as specified above. 

Great care shall be taken around expansion joints, drain-pipes, 
and similar places, where a separation may take place. 

After the mastic is laid, it shall be mopped with pure melted 
asphalt, and the surface shall be spread with a layer of clean, coarse 
sand, to harden the top. 

The pockets of asphalt placed against the girders, stiffeners and 
gussets shall be protected by about 2| inches of 1 : 3 : 5 concrete, 
reinforced with No. 8 or No. 10 wire cloth, electrically welded. 

The furnishing and erection of the steelwork for the bridge to 
be waterproofed will be executed under a separate contract, and the 
riveting will be completed, the erection finished, and the steel floor 
cleaned up ready for the waterproofing, before the work on this 
contract is begun. In addition to the foregoing, the contractor 
shall make a final cleaning of the steelwork before the work of water- 
proofing is begun. 

Specifications for Waterproofing Station and Platform Floors 
of Railroad Viaducts by the Sheet-mastic Method. Where an asphalt 
floor is called for on mezzanines or station platforms, it shall be laid 
on 2-inch, tongue and grooved, yellow pine, the maximum width of 
the board being 6 inches. This board surface shall not be mopped 
with asphalt, but shall be covered with a layer of one-ply building 
paper or untreated felt. Where the asphalt floor is laid on concrete, 
the dry-ply shall be omitted, and a mopping of asphalt substituted. 

The surface mixture shall consist of the following proportions 
by weight: Eleven and one-half (11J) parts of asphalt, ten and one- 
half (10|) parts of sand, thirty (30) parts of grit, forty-four (44) 
parts of limestone dust, and four (4) parts of Portland cement. 

The sand shall be clean, sharp, and free from dirt, mica and 
vegetable matter. It shall contain both coarse and fine particles 
and shall be graded according to the percentages herein specified. 
Sand which does not fulfill the above requirements in its natural 
condition shall be screened, washed, or mixed with other sand to 
produce a result in accordance with said requirements. Of the ten- 
and one-half (10J) parts of sand, 100 per cent shall pass through a 


ten-mesh sieve; 40 per cent shall pass through a forty-mesh sieve, 
10 per cent shall pass through an eighty-mesh sieve. 

All the grit shall pass through a four-mesh sieve, 30 per cent 
through an eight-mesh sieve, and 100 per cent shall be retained on a 
sixteen-mesh sieve. 

All limestone dust shall be of such fineness that it shall leave a 
residue of not more than 20 per cent on a hundred-mesh sieve, and 
not more than 90 per cent on a two hundred-mesh sieve. 

The fineness of the Portland cement shall be such that it shall 
leave, by weight, a residue of not more than 8 per cent on a hundred- 
mesh sieve, and not more than 25 per cent on a two hundred-mesh 
sieve; the wires of the sieves being respectively .0045 and .0024 inch 
in diameter. 

All proportions herein mentioned are by weight. 

The asphalt shall conform to the requirements (given in the 
specifications for " Waterproofing Subways by the Membrane 
System," page 281), except that when 20 grams of the material are 
heated for five hours at a temperature of 325 deg. Fahr. (163 deg. 
Cent.) in an electric oven, the loss in weight shall be not more than 
1 per cent and the penetration shall be between .30 and .50 cm. 
at 77 deg. Fahr. (25 deg. Cent). 

The asphalt floor mixture shall be made in an approved mechani- 
cal mixer or by hand in open fire-heated kettles. When made by 
machine, the ingredients should be weighed out and put into the 
mixer which shall cook and mix the mastic until it is of uniform con- 
sistency and temperature. Pre-heating of ingredients is dependent 
on the type of machine used, and shall be resorted to as directed by 
the engineer. At the end of each day's work, the mixer shall be 
thoroughly cleaned. All materials used in making mastic should 
not be unduly exposed to the weather. The mastic shall be brought 
to the place of application in wooden pails properly covered so as to 
retain the heat. The temperature of the mastic in the mixer should 
not exceed 400 deg. Fahr. (204 deg. Cent.) and it should not be less 
than 300 deg. Fahr. (149 deg. Cent.) at the time of application. 

When the mastic is made by hand, the sand, grit, limestone dust, 
cement and asphalt shall be heated to approximately 325 deg. Fahr., 
the asphalt being heated separately. The maximum temperature 
of the sand, grit and limestone dust, as delivered at the mixing 
kettle, shall not exceed 375 deg. Fahr. (191 deg. Cent.) and the 
maximum temperature of the asphalt shall not exceed 350 deg. Fahr. 
(177 deg. Cent.). 

The Portland cement shall be thoroughly mixed dry with the 


sand, grit and limestone dust. This mixture shall then be sprinkled 
into the hot and molten asphalt until a homogeneous mixture is 
produced, in which all particles are thoroughly coated with asphalt. 

The mastic shall be prepared on or close to the work and in 
amounts not exceeding that quantity which can be laid in one working 
day. The maximum temperature of any batch of mastic immediately 
after being mixed shall not exceed 400 deg. Fahr. and the minimum 
temperature when delivered on the pine floor shall be not less than 
300 deg. Fahr. 

The mastic, containing materials which will become separated 
by subsidence while the asphalt is in a melted condition, shall be 
thoroughly agitated before being drawn and while in the supply 
kettles. Approved methods of agitation shall be used. 

The contractor shall, at his own expense, provide a sufficient 
number of accurate, properly constructed thermometers for deter- 
mining the temperatures of the mastic at all stages of the work. 

After the mixture has been spread and compressed to a uniform 
thickness of one (1) inch, it shall be rubbed to a smooth surface with 
a wooden float. Expansion joints shall be provided where neces- 

Remarks. The above specifications are used by the Public 
Service Commission, 1st Dist., State of New York, on all new elevated 
work of the New York Dual Subway System. The clause calling 
for the board surface not to be mopped, but covered with a layer 
of building paper or untreated felt, is at variance with most similar 
specifications, but has been found necessary to avoid the formation 
of vapor bubbles on the finished mastic surface. The clause per- 
mitting the asphalt floor mastic to be made either in a mechanical 
mixer or by hand, is believed to be a good departure from former 
limitation to hand mixing. 

Specifications for Waterproofing Concrete Floors. Thoroughly 
mix one-half each of D * and tested Portland cement by weight. 
They should be mixed (dry) until absolutely uniform in color and 
showing no streaks. Then set aside until ready for use. 

Lay floor base and topping as usual. The topping should be at 
least f inch thick and should be made of one part good tested Portland 
cement and two parts clean, sharp, coarse sand, free from loam and 
clay. See that the topping is not made too wet, then float well. 

After the topping is laid and evened, as is usually done, powder 
or dust the floor with the D cement mixture, using 30 pounds of 

* These specifications are for the use of a proprietary preparation of finely 
powdered iron, and designated by D. 


mixture (15 pounds each of D and cement) to each 100 square feet 
of topping. Use a small flour sieve for sifting or distributing this 
mixture over the surface. Allow dust coat to stand about five 
minutes, then float mixture in well with wooden trowel and tjowel 

When fairly set, showing no signs of surplus water on surface, 
trowel a second time until the topping has a smooth, hard finish. 

After the floor is from twenty-four to forty-eight hours old, 
cover it evenly with an inch layer of wet pine sawdust or shavings, 
sand or bags and rewet same twice daily for four or five days. Do 
not apply the sawdust, etc., until the floor is thoroughly set, as same 
may adhere to and ruin the finish of the floor. 

Do not use floor for seven days, or while it is curing. Under no 
circumstances should heavy trucking be done on a floor less than 
thirty days old. Cover the floor with boards to assure complete 


The Shingle (Tile) Method. The intention of this specification 
is to secure a watertight roof by the application of a waterproofing 
felt layer and an overlying covering of tiles. The roof, prior to the 
application of the roofing, shall have been constructed in strict 
accordance with the plans. The roof sheathing should be well 
laid and tight, all chimneys and walls above roof line completed, 
and all vent-pipes through the roof properly fastened. 

The gutters shall be placed in position, extending over the roof 
sheathing (and cant strips, if same are used), and under the felt 
and tile at least 8 inches. All valley metal shall be in place, and the 
width of same must be 24 inches with both edges turned up J inch 
for the entire length of the valley. This valley metal shall be laid 
over one layer of felt running the entire distance of the valley. All 
flashing metal used alongside and in front of dormers, gables, sky- 
lights, towers, perpendicular walls, also around vent-pipes and 
chimneys, shall be placed in accordance with the requirements of 
the tiles. 

Upon the properly prepared roof, the sheathing shall be covered 
with one thickness of asphalt or pitch-treated roofing felt, weighing 
not less than 30 pounds per square. The felt should be laid with 
2J-inch laps, and fastened with capped nails. The felt shall be 
laid parallel with the eaves, and lapped about 4 inches over all 
valley metal. It shall also be laid under all flashing metal, and turned 


up about 6 inches against all vertical walls. Upon this felt layer 
the tiles shall be fastened with copper nails. They shall be well 
locked together, lay smoothly, and no attempt shall be made to 
stretch the courses. The tile must be laid so that the vertical lines 
are parallel with each other, and at right angles to the eaves. 

The tiles that verge along the hips shall be fitted close against 
the hip board, and a watertight joint made by cementing the cut hip 
tile to the hip board with a good elastic cement. Each piece of hip 
roll shall then be nailed to the hip board, and the hip rolls cemented 
where they lap each other. The interior spaces of the hip and ridge 
rolls must not be filled with pointing material. 

The tiles shall be of the pattern known as (brand of tile and name 
of manufacturer here mentioned). The tile as specified above must be 
of shale, hard burned, and of (insert color desired) color. All hip and 
valley tile shall be cut to the proper angle before burning. 

Remarks. The above specifications are applicable to pitched 
roofs only. It does not emphasize the importance of the felt layer 
underlying the tiles. The one defect of tile roofing is that it is sub- 
ject to breakage, and when this happens almost sole dependence for 
continued watertightness (until the tile is replaced) is upon the felt. 
Therefore the felt should be applied with care, and be of the elastic, 
built-up, membrane type, that is, consist of at least two plies 
cemented and properly nailed down. The grade and hardness of the 
pitch or asphalt used, as binder, must also be considered. A good 
feature is that it permits the selection and use of many patterns of 

Composition Roofing Method. (A) Over Board Sheathing* 
Lay one (1) thickness of sheathing paper or unsaturated felt weigh- 
ing not less than five (5) pounds per one hundred (100) square feet, 
lapping the sheets at least one (1) inch.. See Fig. 113. 

Over the entire surface lay two (2) plies of tarred felt, lapping 
each sheet seventeen (17) inches over preceding one, and nail as 
often as is necessary to hold in place until remaining felt is laid. 

Coat the entire surface uniformly with coal-tar pitch. 

Over the entire surface lay three (3) plies of tarred felt, lapping 
each sheet twenty-two (22) inches over preceding one, mopping with 
coal-tar pitch the full twenty-two (22) inches on each sheet, so that 
in no place shall felt touch felt. Such nailing as is necessary shall 
be done so that all nails will be covered by not less than two (2) 
plies of felt. 

* This specification should not be used where roof incline exceeds three (3) 
inches to one (1) foot. 



FIG. 113. Details of Built-up Slag Roof over Board Sheathing. 


Spread over the entire surface a uniform coating of pitch, into 
which, while hot, embed not less than four hundred (400) pounds 
of gravel or three hundred (300) pounds of slag to each one hundred 
(100) square feet. The gravel or slag shall be from one-quarter (f) 
to five-eighths (f ) inch in size, dry and free from dirt. 

The roof may be inspected before the gravel or slag is applied 
by cutting a slit not less than three (3) feet long at right angles to 
the way the felt is laid. All felt and pitch shall bear the manufac- 
turer's label. 

(B) Over Concrete.* 1. Coat the concrete uniformly with hot 
pitch, see Fig. 114. 

2. Over the entire surface lay two (2) plies of tarred felt, lapping 
each sheet seventeen (17) inches over preceding one, mopping with 
coal-tar pitch the full seventeen (17) inches on each sheet, so that in 
no place shall felt touch felt. 

3. Coat the entire surface uniformly with pitch. 

4 and 5. Same as for waterproofing roofs over board sheathing. 

Remarks. The above specifications are equally applicable to 
roofs waterproofed with asphalt-treated felt and asphalt binder. 
For best result, with built-up roofings, both the coal-tar pitch and 
the asphalt must be carefully selected, as other than the best grades 
of these materials are very vulnerable to the weather. 

The Tin Roofing Method, f All of the tin used for roofing all 
parts of a building shall be tinned iron sheets, which shall be stamped 
with the brand and thickness on each sheet. 

All tin used for standing seam roofing shall be ICt thickness, 
14 by 20 inches, applied with the 14-inch face parallel to the eaves, 
forming seams with a double lock. All tin for standing seam roofing 
shall be put together in rolls with the cross seams formed and 
soldered, same as specified for flat seam roofing. 

All standing seam roofing shall be fastened to roof with 2-inch 
wide tin cleats, spaced 8 inches apart, with cleats locked into seams, 
and each cleat fastened with two 1-inch barbed wire nails. 

All tin used for flat roofing shall be 1C thickness, 14 by 20 inch 
size, using flat seams, with f-inch lock. Flat seam roofing should 

* This specification should not be used where roof incline exceeds three (3) 
inches to one (1) foot, and when incline exceeds one (1) inch to one (1) foot, the 
concrete must permit of nailing or nailing strips must be provided. 

t Richey's " Building Mechanics' Ready Reference." 

t Plates are made in two weights, 1C and IX. The 1C is No. 30 gauge, 
and weighs 0.5 pound to the square foot. The IX is No. 28 gauge, and weighs 
0.625 pound per square foot. Either grade is suitable for either flat or standing 
seam roofing. 





Pitch^ Felt 


FIG, 114. Details of Built-up Slag Roof over Concrete Slab. 


be made up and soldered in the shop in long lengths, which must be 
painted on under side with one coat of paint and allowed to dry 
before applying to the roof. All flat-seam roofing shall be fastened 
to roof with 2-inch wide flat tin cleats, spaced 8 inches apart, with 
cleats locked into seams, and each cleat nailed to roof with two 1-inch 
barbed wire nails. When the rolls of tin are laid on roof the edges 
shall be turned up \ inch at right angles to roof, when the cleats shall 
be installed. Then another course shall be applied with J-inch 
upturned edge, the adjoining edges shall be locked together, and the 
seam so formed shall be flattened to a rounded edge and well soldered 
and soaked in. 

All valleys shall be formed with flat seam roofing, using 14 by 20 
inch sheets laid in the narrow way, with cross seams put together and 
well soldered, same as specified for flat roofing. 

All flat seams throughout the roof, including such other parts as 
may need soldering to make perfectly watertight, shall be soldered 
with best grade of guaranteed half-and-half solder (half tin and half 
lead), using nothing but rosin as a flux. Not less than 2 pounds of 
solder shall be used per square on standing seam roofing, and not less 
than 8 pounds per square on flat seam roofing, all to be well sweated 
into the joints. 

All rosin used in soldering must be carefully cleaned off from all 
surfaces before any paint is applied to the tin. 

All tin shall be painted one coat on concealed or under side, as 
heretofore specified, and two coats on all exposed surfaces: the first 
coat shall be given four weeks to dry before the second coat is applied. 
All paint shall be applied with hand brushes and well rubbed in. 
Litharge only shall be used as a drier. No patent drier or turpen- 
tine is to be used. The first coat on upper surface shall be applied 
as soon as laid, and the tin must not be permitted to rust before 

Specification for Waterproofing Railroad Station Roof.* All 
roofs in connection with the station buildings shall be made 
absolutely watertight and weatherproof with (name of manufacturer) 
" Built-up Asbestos Roofing " or equal thereto. 

The asphalt shall be (name of brand) or equal thereto and shall 
be applied sufficiently hot to flow freely. 

The felt shall be asphalt-saturated asbestos felt (name of brand) 
or equal thereto. 

The parapet walls, plumbing pipes, smoke pipes, etc., to a height 
of not less than 4 inches, the lower edge of the main roofs and all 
* New York Municipal Railway Corporation, Brooklyn, N. Y. 


roofs at the walls and pipes to a width of not less than 12 inches 
shall be thoroughly mopped with asphalt and therein, while it is 
still hot, shall be embedded one thickness of felt to which a second 
thickness of felt shall be thoroughly wiped with hot asphalt. The 
two thicknesses shall be not less than 4 inches high on the walls and 
pipes nor less than 12 inches wide on the roofs and shall be applied 
before the flashings and roof boxes are set in place. 

After the copper flashings and roof boxes have been set and the 
leaders connected, the surface of the roofs shall be covered with not 
less than three thicknesses of felt laid 10 J inches to the weather, 
thoroughly embedded and wiped down in hot asphalt and well wiped 
to the flashings and leader boxes, the felt to be rolled close behind 
the mop so that no missing of hot asphalt can possibly take place. 

The entire surface shall be finished to a smooth, even surface with 
a heavy coat of (name of manufacturer) " Asphalt Roof Coating " 
or equal thereto. 

All flashings and cap flashings in any way required to make the 
entire work absolutely weathertight shall be furnished as a part of the 
work under this section. 

The' flashings, cap flashings, and roof boxes shall be made of 16- 
ounce cold rolled copper except the flashings and cap flashings to the 
smoke pipes which shall be 20-ounce cold rolled copper. 

The mason shall be furnished the cap flashings to be built into the 
concrete; -these are to be 8 inches wide and built 2 inches into the 
concrete with the built-in edge turned up \ inch; they are to be set 
not less than 8 inches above the roof and where stepped should be 
lapped not less than the height of the step. 

The flashings shall be turned 4 inches under the roofing and shall 
be of sufficient width to fit closely under the built-in portion of the 
cap flashings ; they are to be set after two layers of roofing have been 
applied as hereinbefore specified, and the cap flashings are to be bent 
down and heavily tinned and soldered at all corners and angles. 

All soldering in any way required to make the entire work abso- 
lutely watertight and weatherproof, shall be done in the neatest and 
best manner. The copper which is to be soldered shall be heavily 
tinned and all joints shall be thoroughly sweated and neatly soldered 
over and all superfluous solder shall be neatly removed. 

All sheet metal work and roofing shall be delivered at the final 
completion of the works, clean, whole, perfect, and absolutely water- 
tight and waterproof. 



CONSIDERING the many varied purposes and conditions under 
which the different systems of waterproofing are found serviceable, 
it is surprising how few are the basic waterproofing compounds in 
common use. Not more than fifty of such compounds are in the 
market. Of these compounds the integral system claims about 
30 per cent, the surface coating system about 40 per cent, and the 
membrane and mastic systems about 30 per cent. The grouting and 
self-densified processes are not considered in this connection because 
they require, besides a good grade of material, only scientific manipu- 
lation for successful work. The general nature of most of the basic 
compounds is discussed in Chapter V. On the other hand, of the 
special waterproofing compounds there are at least several hundred. 
The nature of these, of course, is in most instances kept as a trade 
secret. Still, from time to time, some chemists and engineers dis- 
cover or invent useful waterproofing compounds or new processes 
for utilizing old compounds. These are often published in the 
technical press of both the chemical and engineering professions. 
Government chemists, and engineers in particular, are very resource- 
ful and liberal in this regard. The United States Department of 
Agriculture, the Department of Interior and the Department of 
Commerce and Labor, publish annually scores of bulletins and tech- 
nical papers some of which are replete with valuable information, 
suggestions, and tests on new and old waterproofing methods and 
materials,* which are often distributed free and never for more 
than cost. These publications are regarded with great favor and au- 
thority in the waterproofing industry; and well they may be, for they 

are always unbiased, truthful and practical, the only adverse criticism 

* As illustrations of the types of these papers, see Bulletin No. 230 of the Office 
of Public Roads, U. S. Department of Agriculture; Technologic Paper No. 3 
of the Bureau of Standards, Department of Commerce and Labor; Bulletin No. 
329 of the U. S. Geological Survey, Department of Interior. 



being occasioned, in a few instances, by the occasional incompleteness 
of the data and the results based thereon. 

Waterproofing formulas, like paint formulas, are often individual 
secrets, kept by the discoverer from the world for his commercial 
advantage. Like most paints, waterproofing compounds, unless 
investigated by the most competent chemists, often baffle chemical 
analysis, and more often chemical synthesis. The method of com- 
bining, or the process of manufacturing most waterproofing com- 
pounds, is more difficult and kept more secretive than is the knowl- 
edge of the constituent ingredients. Of course, where compounds 
are patented, a certain amount of information is divulged to the 
public, but the patent prevents the unlicensed use of the compounds. 
This facilitates and sometimes encourages the marketing of imita- 
tions, better or worse, which the purchaser must guard against by 
careful investigation. 

In compiling this chapter the author has freely availed himself of 
all the above-mentioned sources with due acknowledgment. In- 
cluded also are formulas and practical recipes derived from personal 
experience and the experience of a few associates in both the 
chemical and engineering professions. In making compounds from 
any of these formulas, care and judgment are essential to success. 
They are arranged under the general heads of Masonry Treatments, 
Treatments for Tanks, Floor Treatments, Roofings, and Water- 
proof Cements, but no strict divisions were attempted. 


Waterproof Mortar. For masonry joints: equal parts of sand 
and cement with sufficient water to form a plastic paste produces a 
very waterproof mortar; for surfacing and stucco work a 1 : 2 
mortar is very efficient provided it is allowed to dry very slowly. 
A mixture consisting of one-sixth underburnt and one-sixth well- 
burnt powdered brick, one-third slaked lime, and one-third sand, 
will make a dense, waterproof mortar. 

Dampproof Coating Compounds for Masonry. An easily made 
and applied coating for dampproofing purposes consists of about 
20 per cent, by weight, of paraffin (melting-point between 104 and 
122 deg. Fahr. (40 and 50 deg. Cent.) dissolved in 80 per cent of a 
petroleum oil mixture. This mixture may be made of about 45 per 
cent benzene, 25 per cent wood turpentine and 30 per cent 


A similar compound can be made by mixing about 5 per cent, by 
weight, of paraffin, 5 per cent alumina resinate, 45 per cent benzine 
and 45 per cent kerosene. 

A good surface-coating compound can be made in the form of a 
thin paste by mixing with water to the required consistency, about 
96 per cent by weight of powdered cast iron and 4 per cent of sal- 
ammoniac. This paste should be carefully applied, preferably in 
two coats with a stiff brush, as it is necessary for it to adhere to the 
concrete to be effective. 

A solution of water glass (about 5 per cent) when applied as a 
coating to a surface containing lime will form a hard, impervious 
finish by the chemical action between the lime and the alkaline 
silicate or water glass. On concrete it is rather difficult to accomplish 
this action because the lime is not free to get at. 

Surface Coatings for Masonry. A liquid, waterproof, surface 
coating, consists of the following formula: 70 per cent of asphalt, 
30 per cent of turpentine substitute or other petroleum product. 
The petroleum product should be added while the asphalt is hot. 
The mixture can then be applied cold with a brush. It may also be 
mixed as an integral compound in mass concrete or mortar in quanti- 
ties ranging between 5 and 10 per cent by weight of cement. 

A plastic form of waterproof surface coating may be made as 
follows: Pine creosote oil, about 40 per cent; fiber asbestos, 30 per 
cent; pine pitch 30 per cent. The pitch and oil must be cooked 
together and the asbestos added while the mixture is hot. This 
material is viscous enough to be troweled on the masonry and can 
be applied to a wet or dry surface. 

A durable, tough, and elastic compound that can be used for 
both roof coverings and flashings consists of a good grade of refined 
asphalt mixed with from 5 to 25 per cent of stearine pitch. The 
proportion is governed by the consistency desired and the melting- 
point of the asphalt. 

The following surface coating will remain plastic and elastic for 
a long time. It is applied cold, by troweling on the surface to be 
waterproofed. Hot elaterite, about 85 per cent; mixed with about 
15 per cent of castor oil or cotton-seed oil. If a little gutta percha is 
added, the compound is considerably improved. 

An impervious surface coating for industrial concrete wash basins, 
etc., can be obtained by rubbing the inside surface with a cement 
brick just after removing the forms. This brick can be made of a 
1 : 2 mortar. While rubbing, the concrete surface should be sprinkled 
constantly with water; this will form a paste over the surface and 


tend to fill the pores. Two or three rubbings in this manner will 
produce a very impervious surface. 

Dampproofing for Brick Walls.* In applying the following com- 
pounds all dampness of the wall must first be allowed to dry up as 
much as possible. The process of dampproofing then proceeds as 
follows: One coat of boiled linseed oil is first applied over the wall 
and all joints. All holes are then puttied up with a paste composed 
of pure linseed oil and whiting, colored with fine brick dust or Vene- 
tian red. Venetian red, thinned with equal parts of boiled linseed 
oil and turpentine, is then applied as a second coat. Finally a third 
coat of red oxide and drier is applied as a finish coat. The color 
may be changed from a red to any desirable tint using white lead as 
the base, tinting with oil color to suit. 

Another formula is as follows: Venetian red mixed with skim 
milk (casein) . The action of the lime base in the Venetian red will 
make the curd of the milk insoluble in water. Should the Venetian 
red be free from lime, then lime water, whiting or quick lime must 
be added to the milk before mixing the Venetian red with it. (To 
ascertain whether the Venetian red contains whiting or lime, a portion 
of it is dropped in some commercial sulphuric acid, and if the red 
powder does not effervesce, lime in the form needed is not present, 
and the aforesaid alkaline addition must be made.) If the color 
is to be waterproofed, however, to each gallon thereof must be added 
one-half gallon boiled linseed oil and well stirred. Both these mix- 
tures, when properly made, will not wash off for years. 

A water-shedding, dampproofing compound for brick and con- 
crete masonry may be made by mixing about 80 per cent of kerosene 
with 10 per cent of acetone and 10 per cent of creosote. This com- 
pound should be applied with a brush and thoroughly rubbed in on 
a clean surface. It tends to fill the pores of the masonry and shed 
water from the surface. 

A damp-resisting paint can be made by mixing, until solution is 
effected, melted Manila or Copal gum with linesed oil or China wood 
oil ; this mixture is then dissolved in benzol or naphtha. It is applied 
with a brush in several coats. For a top coat it is well to evaporate 
more of the gum and add more of the drying oil. The compound 
may also be mixed with any desired pigment. 

Stone Preserving Compositions.! With the following liquid 
compound it is possible to preserve a brownstone front against the 

* " 739 Paint Questions Answered," published by The Painters' Magazine of 
New York in 1904. 

t " Scientific American Cyclopedia of Formulas," 1915. 


weather without altering its appearance, its stony aspect not being 
altered by the liquid after it has penetrated and dried. Ten gallons 
of thinning liquid, such as fish oil, or linseed oil, mixed with 2 pounds 
dry zinc white, and 5 pounds powdered brown oxide. Before apply- 
ing the liquid, the surfaces should be brushed clean with wire brushes. 

Paraffin is the best material for rendering natural stones, con- 
crete and brick-work impervious to water. If dissolved in the pro- 
portion of one-third paraffin and two-thirds kerosene, it remains 
soft longer and penetrates the stone further. Paraffin is unaltered 
by weather or acids. If carefully melted in, it does not change the 
color of the stone; it simply deepens the color like water. It is 
cheap, easily applied and efficacious. It is most easily applied in 
hot weather. 

Leaks in concrete walls can be stopped by enlarging the cracks 
and applying a hot mixture of Portland cement and caustic soda, 
which sets almost instantly. The concrete around the leak should 
be cut out so that the hole or groove is larger at the base than at the 
surface. The hot paste is then applied rapidly with gloved hands, 
first against one side of the cavity and then successively around the 
sides of the cavity until it is completely closed. The soda should 
be mixed with little water and be boiling hot when the cement is 
added in amounts enough to make a stiff paste.* 


Preserving Concrete Tanks from Cemmercial Liquids, f The 

following fluids may be stored in tanks made of plain dense con- 
crete of 1 : 2 : 4 mix without causing any deterioration in the con- 
crete: Menhaden oil, linseed oil, rosin oil, 4 per cent caustic soda 
solution, tanning solution, and sauerkraut. 

For safely storing sulphite liquor and cider vinegar in concrete 
tanks, the only satisfactory method found to protect the concrete 
from disintegration is by applying a surface coat of an oil-gilsonite 
compound. This compound is made by dissolving 100 parts, by 
weight, of gilsonite in 250 parts of turpentine, and adding 5 parts 
of neutral petroleum oil. At ordinary temperatures, with frequent 
stirring, about twenty-four hours will be required for a perfect 

* Engineering Record, March 3, 1917. 

t Results of a series of tests, extending over a period of more than a year, 
made for the Portland Cement Association to determine the effects of commercial 
liquids on concrete tanks, by the Institute of Industrial Research, Washington, 
D. C, Reported in Engineering Record, Vol. 74, No. 16, October 14, 1916. 


solution. Two coats of this mixture, should be applied with a brush 
to the inner surface allowing at least twenty-four hours for each 
to dry. 

For safely storing molasses in concrete tanks, in a manner so that 
neither the molasses nor the concrete is injured, the inner surface 
should be well protected with two coats of Bakelite varnish. Con- 
centrated brines may similarly be stored in concrete tanks by coat- 
ing the inside with two layers of the above-mentioned oil-gilsonite 
compound between which is placed an asphalt-treated fabric. 
Upon this one-ply membrane should be placed a 1 : 2 cement mortar 
coating, and the latter painted with two coats of Bakelite. 

Cement to Resist Benzine and Petroleum.* Gelatine mixed 
with glycerine yields a liquid compound when hot, but which 
solidifies on cooling, and forms a tough, elastic substance, having 
much the appearance and characteristics of India rubber. The 
two substances unite to form a mixture absolutely insoluble in pe- 
troleum or benzine, and the problem of making casks impervious to 
these fluids may be solved by brushing or painting them on the 
inside with this compound. Water must not be used with this 

Wooden and Iron Tanks Made Watertight. Wooden tanks should 
first be drained well and permitted to dry out thoroughly. Then 

the hoops must be tightened and 
the inside be given a coat or two 
of hot paraffin oil or melted paraffin 
wax, applied while hot. This done, 
the iron or steel hoops should receive 
a coat of red lead and the outside of 
the tank one or two coats of good, 
elastic oil paint of any color desired, f 
Joints in iron tanks that have 
opened up can be sealed effectively 
by calking with proper tools (see 
Fig. 115). This operation consists 
FIG. 115. Calking Operation with in beating down the edges of the 
Hand or Pneumatic Calking metal against the face of the opposite 
Tool s- plate. The round -nosed calking 

tool is usually employed in modern 
practice. A more effective way of calking is with lead wool hammered 

* " Scientific American Cyclopedia of Formulas," 1915. 
t " 739 Paint Questions Answered," published by The Painters' Magazine 
of New York in 1904, 


into the joint. Coating the outside of the joint with a thick applica- 
tion of a hard, tough asphalt or a sealing w.x of a similar nature, 
is also effective except for hot-water tanks. Both of these materials 
must be applied on a properly cleaned surface. 

A preserving varnish for wood and metal tanks is easily made by 
mixing three parts of pure asphalt (solid or liquid variety) with four 
parts of boiled linseed oil and from fifteen to eighteen parts of 


Concrete Floor Hardener. The following formula is used for 
hardening concrete floors: Powdered pig iron mixed with about 
2 per cent, by weight, of salammoniac. This mixture may be 
floated on a partially set concrete surface which is thereby hardened 
for a depth of a fraction of an inch, but it is not very durable. The 
mixture may also be combined with Portland cement in equal 
proportions by weight to form a mortar that is applied, about 
f inch thick on a clean surface of concrete. This mortar coat will 
create a dense and impervious floor if properly and carefully applied. 
A serious objection to the use of this formula is the frequent discol- 
oration of the surfaces treated due to the uneven distribution and 
oxidation of the powdered metal. 

Wooden Floor and Flooring Made Watertight.* Flooring 
may be made impermeable by being painted with a solution of 
paraffin wax dissolved in kerosene. The coat will last for about 
two years. 


Roofing Paner.f Old newspapers or sheets of wrapping paper 
in good condition may be converted into waterproof roofing material 
by coating them with hot coal-tar pitch or asphalt with a brush, 
and uniting two or more sheets. These mats can then be applied 
to a roof, shingle fashion, creating a cheap but good roofing for sheds 
and shanties and for temporary, small constructions. 

Roofing Cement. A waterproof bituminous cement for binding 
roofing felt, one that will not flow readily in the summer's heat, 
may be made by mixing one part of burnt lime (but not slaked) 
with seven parts of coal tar, both by weight. The lime is powdered 

* " Scientific American Cyclopedia of Formulas," 1915. 
t " Scientific American Cyclopedia of Formulas," 1915, 


and sprinkled into the hot tar, with which it mixes intimately. The 
mixture hardens on cooling and therefore must be applied hot. 


Adhesives. The following waterproof cements can be made with 
but little difficulty or previous experience:* 

(1) Shellac, 4 ounces; broax, 1 ounce; boiled in a little water 
until dissolved, and concentrated by heat to a paste. 

(2) Carbon bisulphide, 10 parts; oil of turpentine, 1 part; 
mixed with as much gutta-percha as will readily dissolve in the 

(3) Tar, 1 part; tallow, 1 part; fine brick dust, 1 part; the 
latter should first be warmed over a very gentle fire; the tallow 
added, then the tar, and the whole thoroughly mixed. This com- 
pound must be applied while hot. 

(4) Good quality gray clay, 4 parts; black oxide of manganese, 
6 parts; lime, reduced to powder by sprinkling with water, 90 
parts; the combination mixed, calcined and powdered. 

(5) A very strong cement, but one which requires to be applied 
directly after being made as it sets very quickly, is the following: 
Quicklime, 5 parts; fresh cheese, 6 parts; water, 1 part. The lime 
is slaked by sprinkling with water; thereupon it is passed through 
a sieve, and the fresh cheese is added. The latter is prepared by 
curdling milk with a little vinegar and removing the whey. 

(6) A cement adapted for joining stone, metal, wood, etc., can 
be made as follows: Fresh curd, as before, 1 pert; Roman (natural) 
cement, 3 parts. This must be well mixed and quickly applied. 

(7) A cementing paste composed of hydraulic lime and dissolved 
water glass will withstand the action of heat as well as water. 

(8) Glue, 1 part; black rosin, 1 part; red ochre, } part; mixed 
with the least possible quantity of water. 

(9) Glue, 4 parts; boiled linseed oil, 1 part; oxide of iron, 1 part 
all by weight and well mixed together. 

(10) A good cement is made by mixing about 7 parts of litharge 
and 93 parts of burned clay or whiting together reduced to a fine 
powder and made into a paste with linseed oil. 

f (11) A cement may be formed by mixing into a paste freshly 
calcined oyster shell lime, well sifted and ground fine with white of 

* " Scientific American Cyclopedia of Formulas," 1915. 

t " 739 Painters Questions Answered," Painters' Magazine, New York, 


(12) Four parts, by weight, of shellac boiled with 1 part, by 
weight, of borax in water until the shellac is dissolved. This mix- 
ture should be kept boiling until it is of a paste-like consistency. 
To use this paste it must be heated and applied with a clean brush. 

(13) For many odd and varied purposes, commercial sealing wax 
will prove a very good waterproof cement. It consists of hard 
resinous materials, such as lac, with some form of pigment, as ver- 
milion. Beeswax alone or mixed with a fine mineral dust can also 
be used to advantage. 

Waterproof Cement for Leather.* A waterproof cement for 
leather is prepared by dissolving gutta-percha, caoutchouc, benzoin, 
shellac, mastic f and similar materials, in some convenient solvent 
like carbon disulphide, chloroform, ether or alcohol. The best 
solvent, however, in the case of gutta-percha is carbon Ksulphide, 
and ether for mastic. The most favorable proportions are as follows: 
Gutta-percha 200 to 300 parts to 100 parts of the solvent, and 75 to 
85 parts of mastic to 100 parts of ether. From 5 to 8 parts of the 
foimer solution mixed with 1 part of the latter and boiled in a water 
bath to any consistency desired makes a good cement. 

Waterproof Compounds for Textile Fabrics. { Textile fabrics 
can be made waterproof by successive impregnations with a solution 
of soap and a solution of alum. Or, by successive impregnations 
with a solution of alumina sulphate (made by dissolving in ten times 
its weight of water), and a soap solution composed of 1 ounce light- 
colored rosin, 1 ounce of crystallized soda, boiled together in 10 
ounces of water until dissolved. Also by impregnation, first with a 
solution of ammoniacal cupric sulphate of 10 deg. Baume at 77 deg. 
Fahr. (25 deg. Cent.) then, with a solution of caustic soda of 20 
deg. Baume. Increased impermeability will be obtained by using 
sulphate alumina in place of caustic soda. To waterproof one side 
of cloth, it must be imbued on the wrong side with a solution of 
isinglass, alum, and soap in equal parts each dissolved separately, 
and made into a solution with- sufficient water. Another method is 
to impregnate the fabric with hot, molten paraffin. 

Sheets of canvas or tarpaulins may be made waterproof by paint- 
ing the surfaces with or clipping them in a mixture of coal tar, 
gasoline and a good Japan drier in the proportion of 5 : 1 : 1. 

* " The Manufacture of Varnishes and Kindred Industries," by Livache 
and Mclntosh, Vol. 3, p. 376. 

f A form of resin secreted by shrubby trees cultivated on the island of Chios 
in the Greek Archipelago. 

J " Scientific American Cyclopedia of Formulas," 1915, Munn & Co., Inc. 


Waterproof Compound for Drawing and Tracing Sheets.* 
Drawing and tracing sheets can be made waterproof, so that they 
may be used in wet places, as in mines, for instance, by the applica- 
tion, to one or both sides, of a preparation composed of rubber and 
benzol. The preparation is made by dissolving a quantity of pure 
rubber in benzol and thinning down with more benzol to any desired 
consistency. The rubber first swells enormously and in about 
twenty-four hours is ready for use. For use as a waterproof adhe- 
sive the solution should be fairly stiff. Only the pure gum rubber 
is satisfactory for this purpose. 

* Engineering News-Record, Vol. 81, No. 13, September 26, 1918, p. 597. 


WATERPROOFING applied forms an important part of waterproof- 
ing engineering and also a very interesting one. It describes accom- 
plishment in the field. Chemical analyses and physical tests of 
waterproofing materials are important but they are, after all, mostly 
accelerated tests. Service is the real " acid test " for all waterproof- 
ing materials and their application. The best criterion of the rela- 
tive merits of the various materials and systems of waterproofing 
discussed in previous chapters is their efficacy and endurance in 
service. Many secret and patented compounds and various types 
of waterproofing cannot be fairly judged in any other way than by 
their past performences. In fact, certain grades of asphalt have won 
favor and preferance for waterproofing purposes by no other means 
than past service. Coal-tar pitch is extensively used for water- 
proofing underground structures for the same reason. On the other 
hand, many integral and surface-coating compounds proved their 
unworth in this manner though apparently successful in the labora- 
tory. The grouting process of waterproofing is advancing rapidly 
now only because of its efficiency as proved in service. 

In this chapter will be found practical instances of each of the 
six systems of waterproofing previously discussed ; also the standard 
and special materials used, the methods of application and where 
possible the degree of success obtained. 


Water Storage Works, U. S. Reclamation Service. The storage 
works and tunnel connected with the Strawberry Valley Project * 
in the U. S. Reclamation Service are located in the Wasatch Moun- 
tains at an elevation of 7500 feet, surrounded by mountains, some of 
which reach an elevation of 10,000 feet above sea level. There is a 
wide variation in temperature in this vicinity during the entire 
* Enginerring News, Vol. 73, No. 15, April, 1915. 


year, and the climate is very severe during the winter months, the 
lowest temperature on record being 50 deg. Fahr. below zero. The 
snowfall ranges from 10 feet in low years to 24 feet in high years. 
On account of these conditions of extreme cold, with alternate thaw- 
ing and freezing, the action of water and frost on concrete that is 
not impervious is very marked. It was therefore decided to treat 
the concrete with some sort of preventive against absorption of water 
by the surfaces exposed. 

A study was made of the various waterproofing processes in com- 
mon practice. Because the structures had been completed, and in 
view of the extraordinary conditions, it was decided to treat the verti- 
cal surfaces with alum and soap solutions (Sylvester process) and the 
horizontal ones with paraffin. 

The alum solution was made by dissolving 2 ounces of alum in 
1 gallon of hot water. The soap solution was composed of f pound 
of castile soap dissolved in 1 gallon of hot water. The paraffin 
was boiled to rid it of any water content, as the presence of water 
rendered it hard to apply. Ordinary commercial products were 

The surface to be treated with paraffin was first entirely freed from 
all moisture, loose concrete, dirt and other foreign substances. The 
paraffin was then heated and applied to the surface of the concrete 
with a paint brush and was forced into the pores by flashing the 
flame of a blow torch over the surface. 

In the application of the alum and soap (which produces an in- 
soluble aluminum stearate in the pores and on the surface of the 
concrete), the surface of the concrete was first prepared in the same 
manner as for the paraffin treatment. The alum solution was 
then applied at a temperature of 100 deg. Fahr. with a moderately 
stiff brush, and was then worked in with a stiff horse-brush. While 
the surface was still moist from this treatment the hot soap solution 
was applied in the same manner. One treatment with each solution 
in the manner described above constituted a coai. If other coats 
were deemed necessary, they were applied in a manner similar to the 
first coat, after the preceding coat had been allowed to stand twenty- 
four hours or more. The work of application was carried on by two 
men, one applying the solution and the other following and working 
it in as described above. 

No actual tests were made to determine the imperviousness of 
the concrete after treatment, but the structures that were repaired 
and treated have gone through two severe winters and no further 
disintegration of the concrete on any part* thereof has occurred. 


Gate Houses of Croton Reservoir.* In the New York City 
Croton Reservoir the face walls of the back bays of gate houses were 
built of hard-burnt brick laid in cement mortar. A space between 
the walls 4 feet wide was filled with concrete. The brick walls were 
12 inches thick and 40 feet high and impounded water under a 
head of 36 feet. When the reservoir was first filled and water let 
into the gate houses, it filtered through the walls to a considerable 

The Sylvester process for repelling moisture from external walls 
was used to waterproof the walls of these gate houses. This con- 
sisted of two washes or solutions for covering the surface of brick 
walls, one composed of castile soap and water and one of alum and 
water. The proportions were f pound of soap to 1 gallon of water; 
and | pound of alum to 4 gallons of water, both substances being 
perfectly dissolved in the water before being used. 

The first, or soap wash was applied, at boiling heat, with a flat 
brush, taking care not to form a froth on the brick work. This 
wash remained twenty-four hours so as to become dry and hard 
before the second or alum wash was applied ; which was done in the 
same manner as the first. The temperature of this wash when 
applied was between 60 and 70 deg. Fahr. At least twenty-four 
hours elapsed before a second coat of the soap wash was put on. 
These coats were repeated alternately until the walls were made im- 
pervious to water. Four coatings rendered the brick wall imperme- 
able under a pressure of 40-foot head. The cost was about ten cents 
per square foot for four coats. 

Retaining Walls, Rock Island Pailrcad. The retaining walls 
and abutments on the Chicago track elevation work of the Rock 
Island Railroad Lines are waterproofed with a coal-tar pitch com- 
position applied to the back of the walls. The expansion joints of 
these walls were waterproofed by placing a strip of burlap and felt 
over each joint and mopped with the same composition. Later 
observations showed these coatings to be satisfactory. 

Beaver Park Dam.f The Beaver Park Dam in Colorado is a 
masonry structure of the rock-fill type. It was made watertight 
by the application of reinforced concrete facing to its upstream 
face, as indicated in Fig. 116. This concrete face was placed with 
no rods or ties to secure it to the rubble face of the dam, as the 
interstices in the rubble face were depended upon to give sufficient 

* Abstract of Paper read before the American Society of Civil Engineers by 
Mr. Wm. L. Deardon, May 4, 1870. 

t Engineering News, Vol. 73, April 8, 1915. 



bond between the concrete and the hand-laid wall. The concrete 
is reinforced horizontally and vertically with wire fabric of diamond 
mesh, the main wires being No. 4 gauge, spaced 5 inches apart. No 
expansion joints were provided, and although the concrete face has 
been exposed to severe temperature conditions, few or no tempera- 
ture cracks have occurred. 

The concrete in the lower portion of the wall forming the water 
face and in the gate tower was of 1:2:4 mixture, the aggregate 
consisting of crushed trachite, while the upper portion of the wall 
and tower was made of a mixture consisting of practically equal parts 
of sand and gravel. Up to a point about 20 feet below the crest, 
a calcium-oleate waterproofing compound was added to the water 
used to gauge the mixture. The specifications provided that one part 

JE1.194 K-16*) 
H.W.L.E1 185 

1 Slope, Rubble 

Masonry pointed 

with Cement Mortar 


FIG. 116. Sections through Beaver Park Dam Showing Waterproof Facings. 

of the compound was to be added to an equal amount of water 
and thoroughly dissolved, after which eleven more parts of water 
were to be added, and this solution used in mixing the concrete for 
all 24-inch walls and a somewhat weaker solution for thinner walls. 
The results obtained by using this compound seemed so unsatis- 
factory to the engineer, that its use was ordered discontinued, and 
extra cement was added to the concrete at the same cost, which gave 
much better results. 

Queensboro (Steinway) Tunnel. The Queensboro tunnel in 
New York City (formerly known as the Steinway tunnel), is about 
80 feet below ground-water level in water-bearing rock. In its 
reconstruction the stations were enlarged and waterproofed. It was 
proposed to waterproof one very large station by the membrane 
system, and two remaining small ones by the surface-mortar-coating 
system. The membrane was to consist of six plies of treated fabric 
laid in coal-tar pitch and applied over the arch as shown in Fig. 117. 
For lack of head room and on account of the great expense involved 
in securing this head room the membrane was not installed. In- 



stead, a waterproofed surface mortar-coat was applied. In 1916 
the two small stations and a portion of the very large station were 
treated with a 1-inch mortar coat, waterproofed with a proprietary 
liquid compound composed of a mixture of calcium chloride and a 

Proposed 6 ply waterproofing 

membrane, abandoned for 

lack of headroom. 

Pay line for 

Net line 

FIG. 117. Typical Half-section through Station. 

carbohydrate and applied with a trowel on the inside of the arch and 
sides. This surface mortar coat contained about 7 per cent of the 
waterproofing liquid (added to the gauging water) was easy to apply 
but troublesome after application, required repairing, and even then 
it did not remain entirely impervious thereafter. In 1917 the remain- 


ing and major portion of the large station was waterproofed by the 
application of a similar mortar coat J inch thick, made of a 1:2 
mixture containing an alum-soap paste compound mixed in the pro- 
portion of one part paste to fifteen parts of gauging water. As a 
result of this work the leakage was markedly reduced. Some blast- 
ing in the vicinity may have contributed to the difficulty of making 
these waterproofed mortar coats entirely impervious. 

Nashville Water Works Reservoir. In repairing and water- 
proofing the Nashville Water Works Reservoir * precaution was 
taken against cracks opening at the junction of the new masonry 
with the old, by using a flexible U-shaped, heavy, sheet-lead stop 
joint. This was inserted by cutting a dove-tail groove in the con- 
crete core from bottom to top of the ends of the old wall, and by 
anchoring one end of the lead joint therein with rich concrete in 
advance of the new masonry, but leaving the other end free. The 
fold in the joint was protected with tar felt to assure free movement, 
and the new masonry was built around the free end thereof. This 
contrivance was simple, effective, of very little trouble, and inex- 
pensive. See Fig. 118. For waterproofing the interior face of the 
walls, the cement gun was used and the work proceeded in the fol- 
lowing manner: The walls were first thoroughly cleaned of all 
scale and foreign matter by means of pneumatic-hammer chisels 
so as to afford sound stone faces for the mortar. By the same 
means the old mortar joints were gouged out to depths varying from 
1 to 3 inches for the cement-gun mortar. The walls were therl 
sinrl-blasted and sprayed immediately in advance of the cement- 
gun, resulting in clean, sound, stone faces and mortar joints. 

The cement-gun mortar, composed of one volume of Portland 
cement to three volumes of clean sand, followed right behind the sand 
blasting and spraying before the walls could dry. The whole 
interior of the walls, including the new masonry, was thus coated 
and made watertight. 

Before laying the asphalt-treated felt membrane used to water- 
proof the floor, the old concrete floor was carefully cleaned and 
flushed off with a powerful stream, and all loose scale removed. All 
rough places and sharp depressions were then filled and brought to a 
smooth plane with rich cement mortar. After thoroughly drying, 
the floor was well painted with a priming coat of asphalt dissolved 
in naphtha. This was followed with a very heavy coat of asphalt 
heated to a temperature of about 325 deg. Fahr. The asphalt- 
treated felt followed closely behind this mop coat, in alternate layers 
* Engineering News, Vol. 73, May 6, 1915. 



of felt and heavy mop coats. Each layer of felt was carefully rolled 
down before the succeeding coat and next layer of felt were applied, 
care being taken to squeeze out all the air bubbles. The felt over- 

6 Ply 

Limestone facing stones 
laid ia Portland Cetneut, 
mortar to match exist- 
ing wall 

Broken stone 

around i" Vit. 
drain laid with 
open joints, 
slope 1:100 

All reinforcing rods to Theoretical inside 

;o /Theoretical in 
J line of wall 
I i" A^////^/ 

(Theoretical inside 
VJ Hne of wall 

71., / '//////. 

30. toC. 

_ g Asphalt 




FIG. 118. Showing Waterproofing Details of Nashville Reservoir Wall and 


lapped and broke joints 3 inches on longitudinal edges and 10 or 
12 inches on ends. Five layers of the felt were employed, ending 
with a heavy mop coat all over the top. 


The reservoir, repaired as above described, was for all practical 
purposes watertight for over two years. In May, 1916, it was 
emptied during the warm weather for cleaning. During the process 
of cleaning and removing the mud out of the basin, the cement-gun 
mortar was exposed to the sun's rays, and badly checked and cracked. 
These defects were corrected by cutting the mortar out of all visible 
checks and cracks to the original masonry. These cut-out cracks 
were then rilled with cement gun-mortar. A water curtain was 
then provided to sprotect the walls from the effect of the sun's rays. 
This was accomplished by means of a perforated pipe kid around 
the inner edge of the top of the wall, from which the water trickled 
down and spread over the mortar lining. By these means, the basin 
was again made watertight. 

The Hudson-Manhattan Tunnels.* Wherever work was executed 
by open-cut methods on the Hudson-Manhattan Tunnels, between 
New York and New Jersey, the" structure was waterproofed with 
treated fabric and coal-tar pitch applied in the usual manner, making 
a complete envelope around it. As the greatest part of this work, 
however, was executed by tunnel methods this manner of waterproof- 
ing was not feasible except in small portions of the work. The 
method adopted, therefore, was invariably to grout with Portland 
cement in the rear of the cast-iron ring lining or concrete lining, and 
in the majority of cases this application 'answered the purpose of 
making the tunnels perfectly watertight. Owing to the impervious- 
ness of neat cement this was the only waterproofing adopted 
on the coffer-dam walls of the Church Street terminal and 

In the iron-lined sections of the tunnel all joints of the plate 
segments were made watertight by grommetting the bolts with flax 
and red lead under the bolt washers, and calking the spaces between 
the joints of the plate lining with a thread of lead wool, followed up 
and supported with rust-joint cement. Throughout the concrete 
work, waterproofing was done by plastering the internal and exposed 
surface with one of the usual types of waterproofing compounds 
mixed with neat Portland cement and applied with a trowel, this 
method answering admirably in a majority of cases. At the same 
time, in persistent leaks, it was found necessary to cut right back 
into the concrete and expose the voids and then reconstruct such 
portion of concrete with a rich mixture of cement. As a general 
rule, for waterproofing of concrete work a rich mixture of cement in 

* " Subways and Tunnels of New York," by G. H. Gilbert, Lucius I. Wight- 
man and W. L. Saunders. 


the concrete with thorough and efficient ramming answered the 
purpose and constituted the only waterproofing used. 

Reinforced Concrete Standpipe. At Attleboro, Mass., a large 
reinforced concrete standpipe, 50 feet in diameter, 106 feet high from 
the inside of the bottom to the top of the cornice, and with a capacity 
of 1,500,000 gallons, has been constructed and is in the service of the 
waterworks of that city. The walls of the standpipe are 18 inches 
at the bottom, and 8 inches at the top. A mixture of 1 part cement, 
2 parts sand, and 4 parts broken stone, the stone varying from J inch 
to 1| inches, was used. The forms were constructed, and the con- 
crete placed, in sections of 7 feet. When the walls of the tank had 
been completed, there was some leakage at the bottom with a head 
of water of 100 feet. The inside walls were then thoroughly cleaned 
and picked and four coats of plaster applied. The first coat con- 
tained 2 per cent of hydrated lime to 1 part of cement and 1 part 
of sand; the remaining three coats were composed of 1 part sand to 
1 part cement. Each coat was floated until a hard, dense surface 
was produced; then it was scratched to receive the succeeding coat. 

On filling the standpipe after the four coats of plaster had been 
applied, the standpipe was found to be not absolutely watertight. 
The water was drawn out; four coats of a solution of castile soap 
and one of alum (Sylvester process) were applied alternately, 
and under a 100-foot head, only a few leaks then appeared. Prac- 
tically no leakage occurred at the joints; but in several instances a 
mixture somewhat wetter than usual was used, with the result that 
the spading and ramming served to drive the stone to the bottom 
of the batch being placed, and, as a consequence, in these places, 
porous spots occurred. The joints were obtained by inserting 
beveled tonguing pieces, by thoroughly washing the joints and 
covering them with a layer of thin grout before placing additional 


East View Tunnel.* Tunnels are usually not waterproofed by the 
membrane system because of the difficulty of applying the membrane 
and making it adhere to the arch. Therefore the grouting process 
is generally used. The surface-coating system can also be used 
successfully, but the materials must be carefully chosen and applied. 
But it may be impossible to employ either of these systems with good 
results because of the presence of disintegrating agents in the soil 
* New York Board of Water Supply Report 1916, p. 135. 


or rock through which the tunnel passes. Under such condition 
the membrane system is best used, and a case in point is the 
following: A 1700-foot portion of the East View Tunnel of the New 
York Catskill Aqueduct was built in rock containing iron pyrites 
from which the compound, sulphuric anhydride (SO p.) is dissolved by 
the ground water, forming sulphuric acid. This solution, percolating 
through the seams of the rock, attacked the limestone aggregate of 
the concrete and also the cement sufficiently to cause disintegration 
in the concrete lining of the tunnel. It was therefore decided to 
waterproof this section by means of a 3-ply bituminous membrane. 
The method pursued in doing this work was as follows: To the 
face of the partly disintegrated lining was nailed, shingle fashion, No. 
28 gauge sheet iron. This acted as a shedding surface for the drip 
and a dry-ply upon which the membrane was applied. The fabric, 
which was 3 feet wide was cut up into 6-foot lengths preparatory 
to applying same. Hot asphalt was mopped on the sheet iron over 
an area equal to about half the width of the 6-foot strips. Then a 
strip of fabric was applied (transversely to the center line of the 
tunnel) and pressed into the binder. The other half of the strip 
was similarly applied. The second and third plies were laid up like- 
wise, the top ply receiving a final coating of asphalt on its entire 
surface. Within and against this membrane a brick wall, 1 foot 
thick, was built completely around the waterproofing. 

On the completion of this work the cracks and crevices in the 
semi-disintegrated concrete, and also the space between the sheet 
iron and the concrete lining, were grouted. For this purpose 3-inch 
pipes were attached to the sheet iron and waterproofed around the 
joint before the brick wall was built. The results obtained by this 
method of waterproofing the tunnel proved entirely satisfactory. 

The asphalt used on this work was a Mexican refined asphalt 
with a penetration of .55 cm. at 77 deg. Fahr. The fabric was a 
saturated cotton drill. The asphalt was heated in the tunnel in a 
rectangular kettle whose source of heat was a battery of gasoline 
torch burners under it. The gas, contained in a tank under pressure, 
consisted of about one part gasoline to four parts kerosene. 

Long Island Railroad Subway. The Atlantic Avenue section 
of the Long Island Railroad * in Brooklyn, N. Y., is built of con- 
crete (see Fig. 119). The 5-foot arches, forming the roof are sup- 
ported by transverse I-beams. This roof was waterproofed in the 
following manner: After the concrete had thoroughly set and been 
well dried out by the sun, the upper surface was swabbed over with 
* " Modern Tunnel Practice," by D. McNeely Stauffer. 



hot, medium-hard, coal-tar pitch such as will soften at a temperature 
of 60 deg. Fahr., and melt at a temperature of 100 deg. Fahr. as deter- 
mined by the cube-ih-water method. The coal-tar pitch was put 
on until it had a uniform thickness of not less than T$ inch. Imme- 
diately upon the first coat, and while it was still melted, was laid 
1-ply of felt, lapping at least 4 inches on all cross-joints, and at least 
12 inches upon all longitudinal joints. The felt was at once covered 
with a uniform thickness of the coal-tar pitch, and upon that was laid 
a second ply of felt which was also covered by not less than y inch 
of coal-tar pitch. This membrane extended over the ends and down 

4. Iron Bands MX 2 

( Staggered 30 C . to C . 

\ Cross-section through Manhole. \ Cross-section between Manholes. 

FIG. 119. Cross-section of Atlantic Avenue Subway, Brooklyn, New York. 

the sides, as shown in the cross-section. After the waterproofing 
had thoroughly hardened, a 1-inch layer of Portland cement mortar 
was laid uniformly over it with a trowel. This mortar coat was laid 
in 5-foot squares alternately for the purpose of providing for expan- 
sion and contraction. The work was accomplished without difficulty 
and with very good results. 

Manhattan-Bronx Rapid Transit Subway. The first Rapid 
Transit Subway in New York City built and finished between 1900- 
1903, was waterproofed with a membrane composed of two to eight 
plies of felt, each mopped with hot asphalt, as laid. On several 
small sections of the subway, the felt waterproofing was made more 


effective by the application of one or two courses of hard-burnt 
brick laid in hot asphalt mastic. This was generally against the 
2-ply membrane. The membranous waterproofing on the exterior 
surfaces of the masonry shell made it unnecessary to provide an 
extensive system of drains or sump pits of any magnitude, for the 
collection and removal of water from the interior of the subway. 
A few leaks have developed, mainly due to enlarged cracks, which 
required extensive repairs; but in general the waterproofing is good 
after twelve years' service. 

The Dual Subway System, New York City.* Two types of water- 
proofing were used on the 48 miles of new two-, three-, and four- 
track subways, viz., the bituminous membrane and the brick-in- 
mastic envelope (the latter, described under examples of mastic 
applications), the former on the roof between stations and on side 
walls at stations when above mean high or ground water; the latter 
both at and between stations on roof, side walls and floor when below 
mean high or ground water. See Table XXI for details. 

The fabric used for the membrane was 7J and 8 ounces open- 
mesh, jute burlap saturated and coated with bitumen. 

The application of the membrane to the roof is typical of its 
general use on the entire structure. The concrete roof was swept 
clean and all surface projections chipped away. The smooth sur- 
face, if dry, was then carefully mopped with coal-tar pitch, using 
ordinary wash mops for this purpose. The treated fabric was care- 
fully unrolled on the mopped surface (see Fig. 120) stretched across 
the entire width of the subway, where possible, overlapping 1J feet 
on either side. As it was unrolled it was pressed into the still hot 
coal-tar pitch and its surface mopped. A bond with the first coat 
of binder on the concrete surface was thus made through the open- 
mesh of the fabric. A second ply of fabric was then applied so 
that it broke joint either at the middle or at the one-third point of the 
width of the fabric. The surface of this layer was similarly mopped. 
A third strip of fabric was applied, breaking joint over the second 
and carefully pressed into the still hot binder. This process con- 
tinued until the required number of plies were laid. The surface of 
the top ply then received a final coating of binder, leaving it smooth. 
The waterproofing membrane that was thus formed was allowed to 
cool after which a 4-inch protective coat of concrete was placed 
thereon extending over the entire width of the subway. 

* Public Service Record, published by the Public Service Commission for 
the State of New York, First District, November, 1915, D. L. Turner, Chief 



At the time of its application the pitch had a temperature of 
325 deg. Fahr. in warm weather and 375 deg. Fahr. in cold weather. 
No waterproofing was done during an air temperature below 
34 deg. Fahr. 

A few leaks developed during construction, but almost without 
exception proved to be due to careless workmanship, such as tares 
or punctures or foot-square holes accidently left unwaterproofed 
on the removal of struts and shores. 

FIG. 120. Showing Method of Applying Treated Fabric on Roof of Subway. 
(Note Rolls of Fabric, Pitch-carrying Pails, and Mop.) 

Bergen Hill Tunnels, Pennsylvania Railroad.* In waterproofing 
the Bergen Hill tunnels of the Pennsylvania Railroad System, 
three general types of construction for the arch were decided on, 
as shown in Fig. 121. The first, as shown at A, was to be used where 
the tunnel was quite dry. In this type the sand wall was omitted 
entirely and the concrete and rock packing were built up together, 
the rock packing impinging to a certain extent on the concrete and the 
concrete squeezing somewhat into the rock packing. The section 
shown at B was used where the tunnels were damp or where there 
were slight droppers, not forming a continuous stream. The back 
lagging of 1-inch boards, which was left in place provided a practically 
smooth outer surface on the concrete arch and allowed the concrete 
and rock packing to be built almost simultaneously. It was con- 

* Transactions of the American Society of Civil Engineers, Vol. 68, p ; 142. 



sidered that the free drainage through the rock packing, the surface 
of the boards and the smooth outer surface of the concrete in the 
arch would allow the comparatively small quantity of water in these 
parts of the tunnel to find its way to the sides, thence to the ditches 
at the bottom, rather than percolate through the concrete. This 
proved to be very generally the case, as is shown by the dry condition 
of the tunnel as built. The back lagging was used over the arch, 

Method of 

Method of making la PP in * Mats 

Three-ply MaU 


One layer of felt with 4" overlap to 
be nailed to lagging of inch boards, 
using tin washers on nails over the 
whole of the intrados of the arch be- 
fore starting any concrete or placing 
any of the permanent felt and pitch 
waterproofing. The waterproofing 
over the arch can be laid in mats of 
three thicknesses of felt properly 
joined together with pitch made as 

shown diagrammatically at x. 
Each of these mats of three-ply felt 

will be overlapped half the width of 

the mat, as shown diagrammatically 

at y. 

FIG. 121. Various Types of Arch Waterproofing Used on Bergen Hill Tunnels. 

both where the sand wall was built and where it was omitted, as well 
as being placed over the waterproofing of the arch as an armor 
course where waterproofing was required. Where the sand walls 
were built and waterproofed, and where the waterproofing was not 
carried over the arch, the waterproofing was turned in at the top, 
as shown at C. 

The third method provided for waterproofing the whole of the 
arch. This was the same as B except for the addition of the water- 
proofing inside the back lagging. In placing this waterproofing, 
the felt was cut in strips about 11 feet long (about 1 foot longer than 
the length of a section of arch) and six thicknesses were cemented 


together with hot coal-tar pitch. These mats were then laid, shingle- 
fashion, as shown at D, up the sides of the arch until a space about 
5 feet wide remained at the crown; shorter mats were then brought 
out over this, laying them perpendicular to the axis of the tunnel. 
Care was taken in making all laps, irrespective of the direction in 
which the arch was built, so that they would lay with the grade, 
that is, so that the water would tend to flow over the edges of the 
laps rather than against them. 

The method of waterproofing that part of the timbered section 
which was very wet is shown at F. A lagging of 1-inch boards 
was nailed up the sides sjid to the soffit of the segmental timbering, 
all the spaces outside of this lagging being carefully filled with rock 
packing. Before starting any concrete work a single thickness of 
waterproofing felt was nailed to the inner side of the lagging, which 
not only served to protect the finished surfaces of the concrete 
from the water which fell copiously from the roof, but also provided 
a comparatively dry surface to which the regular 6-ply waterproofing 
could be cemented with pitch and held in position while the concrete 
was placed against it 

Boston Tunnels.* A section of the Boston, Mass., subway con- 
sists of two tunnels underneath the Fort Point Channel. These tun- 
nels are built with an outer shell 9 inches thick made of Southern 
long-leaf pine-wood segments and an inside concrete shell 2 feet thick 
(minimum) with steel reinforcement. These tunnels are water- 
proofed by the application of a bituminous membrane to the interior 
of the wooden shell before placing the interior concrete lining (see 
Fig. 122). This membrane consists of layers of treated cotton fabric 
mopped with hot asphalt. Two layers are put on 'the invert and three 
on the sides and arch. In applying the waterproofing to the sides 
and arch, the first layer of cloth was mopped on one side with asphalt 
and then nailed to the wooden lining with roofing nails, the mopped 
side being against the wood. The second and third layers were 
then stuck on with successive moppings of hot asphalt. The result 
after three years' service is entirely satisfactory. 

Waterproofing Railroad Viaducts. The following unique method 
of waterproofing the Martins' Creek and Tunkhannock Viaducts 
on the new line which the Lackawanna Railroad has recently built 
west of Scranton, Penna., is described as follows by Mr. G. J. Ray, 
Chief Engineer. f "The structures referred to were treated alike, 
the same waterproofing materials being used in each case. The 

* Engineering Record, August 21, 1915. 

t Engineering News, Vol. 75. March 2, 1916. 



floor system over each main arch is divided into three parts by four 
transverse expansion joints two adjacent to each pier and one at 
each of the quarter points of the span. The floor is drained by 
downspouts through all spandrel walls, excepting those at the 
two intermediate expansion joints, and the drainage is discharged 
into the openings between the two ribs of the main arch. The 
drainage is prevented from flowing over the expansion joints by 
dikes built across the floor (enlarged details are shown in Fig. 123). 
" The waterproofing proper was done by using three plies of 
saturated cotton fabric laid in hot asphalt. The concrete was first 

FIG. 122. Waterproofing is Placed against Wooden Lining and Outside of 
Concrete on Shield-driven Tunnel, Boston, Mass. 

mopped with the hot asphalt. The three layers of cloth were then 
laid in the usual manner, each layer being mopped before the applica- 
tion of the succeeding layer. This waterproofing was carried up 
the sides of the parapet wall to the top of the ties and directly across 
all expansion joints, so that the waterproofing was in reality continu- 
ous from one end of the bridge to the other. At the expansion joints 
one additional layer of the saturated fabric was laid across and 
folded in the expansion joint beneath a copper flashing, similarly 
laid, over which the three layers of waterproofing were placed. A 
fold was provided in the waterproofing at the joints to provide 
for expansion and the entire joint filled with the hot asphalt. 



" As a protection to the waterproofing, asphalt-mastic mixed with 
washed torpedo gravel, was applied hot in two f-inch layers over the 
entire area of the waterproofing. In order to avoid injury to the 
waterproofing by the hot mastic, 1 ply of asbestos felt was first laid 



3-Ply Cloth 
16-oz Copper "A" 
1-Ply Cloth 



FIG. 123. Dike Form of Expansion Joint, and Details of Waterproofing on the 
Martin's Creek Viaduct. 

over the entire area of the membrane. An opening was left in the 
mastic directly over the center of each expansion joint and filled with 
the hot asphalt. The asphalt-mastic was used for protection in prefer- 
ence to brick or concrete, since our experience elsewhere with this 
mastic, under ballast, indicates that it does not crack and in reality 


forms a secondary waterproofing surface on which the drainage 
readily passes to the downspouts." 

Terrace, United States Capitol. The pavement over the terrace 
chambers of the United States Capitol at Washington, D. C., has 
been made watertight by the membrane system after many failures 
by other systems.* 

Many methods of waterproofing have been tried on this great 
expanse (about 200,000 square feet) of walk, to wit: felt and coal- 
tar pitch, asphalt and burlap, sheet asphalt, etc. In 1906 a sheet- 
lead pan was placed under one section. The sheet lead was bedded 
in cement mortar on the base slab and was covered with a 3-inch 
reinforced concrete slab and a 1-inch wearing surface. But even 
this construction was of no avail, partly because of the extreme 
expansion movement, partly because of unskilled burning of the sheet 
joints and partly because of the inherent difficulties of flashing 
around the vault light frames. The sheet lead on being uncovered 
was found to be considerably pitted. 

The expansion and contraction movements of the terrace struc- 
ture are excessive, owing to wide variations in temperature and 
extreme exposure.' Insufficient provision was made for inevitable 
expansion movement, and to this defect can be finally traced the 
repeated failures to keep the terrace chambers watertight. Final 
success was largely due to recognizing expansion difficulties and pro- 
viding for such movement by watertight, sealed expansion joints. 

Specifications were issued for this work in 1914. The notable 
features of these specifications consisted (1) in securing a bituminous 
compound having maximum adhesiveness and cohesion, (2) in using 
small (1 square yard) freshly saturated cotton fabric sheets, with 
wide laps, mopped into place and covered with protective masonry, 
(3) in the free use of special expansion and flashing joints. 

The material over the terraces was removed down to the con- 
crete slab over the floor arches which disclosed numerous fractures 
in the base slab. Each crack, treated as an expansion joint, was 
cleaned out, heated with a gasoline torch, partly filled with a special 
asphalt compound and tooled with a hot iron as shown in Fig. 124. 
The slab was also cut for expansion joints, as shown in Fig. 125. 

After the expansion joints were filled, the pavements were 
brought up to subgrade by a filling of 1 : 3 : 6 concrete. Upon the 
leveled subgrade was laid single sheets of impregnated cotton drill. 
The sheets were 1 yard square and were laid with 2-inch laps. A small 
area of subgrade was cleaned and mopped with hot compound just 
* Engineering News, Vol. 76, No. 14, October 5, 1916. 



previous to laying each sheet. The laps were made tight by follow- 
ing with a hot smoothing iron. Upon the membrane thus made there 
was laid, as armor for the waterproofing and as a wearing surface, 
a granolithic pavement (1:1:2 mixture with i to f inch washed 
bluestone chips), marked off in squares. These squares were sepa- 
rated by expansion joints continuous with the expansion joints in 
the subbase, as shown in Fig. 125, also along the balustrades, vault 
lights, and at every point where flashing would ordinarily have been 

In waterproofing the expansion joints, the cut in the bottom slab 
was heated, painted and partly filled with the asphaltic compound. 
Then the membrane was brought down into the opening and the joint 
pointed with mortar. The joint was covered with a patch strip 

FIG. 124. Slab Cracks Made into Expansion Joints in Waterproofing the 
Capitol Terraces, Washington, D. C. 

(see detail X on Fig. 125), completing the lower half. When the 
granolithic paving was laid, wood strips, tapered f to J inch, were 
inserted as joint forms. When the concrete had set, the wood was 
pulled out, the opening heated and partly filled with the compound. 
The remaining space was pointed with mortar. In this way a covered 
and sealed reservoir was created at, each expansion joint. As the 
structure contracts and expands, the mortar plug is drawn down or 
forced out, the seal being preserved. After one summer's use the 
joints were found all closed nearly tight, demonstrating that by use 
of a thin plastic membrane underlying the wearing surface the latter 
could be kept from spalling or cracking. 

Manhattan and Brooklyn Railroad Viaducts. In building rail- 
road viaducts through city streets, where space is usually very 
valuable and scarce, and economy of operation the governing factor 
in the type of structure required, it has become the practice to con- 
struct the stations underneath the track level, instead of projecting 





them into the side streets on a level with the tracks. This new 
practice necessitates the portion of track floor or road bed directly 
over the station mezzanine to be perfectly watertight. To best 
accomplish this the steel work at these locations of the elevated 

No.18 Galranized wire lath 1^'mesh 
1' 6" wide across brackets. 


_ '. ':. ..-^..v...' ;/-.;-;:-v:-J-., . ... ..::-.-.....: .--. ^JU ..-.- :' 

T- N N6.18 Galvanized wire lath 1J m 

/ f Waterproofing shall be flashed 3'0"wide, entire length. 

V < over brackets and against girders 
v to form a perfect seal. 












FIG. 126. Method of Waterproofing Concrete Decks on Through Spans, Used 
by the New York Municipal Railway Corporation. 

structure should be designed free of bays and unnecessary connections, 
and should also be encased in concrete. This concrete, forming the 
roadbed, may be constructed in sections as shown in Fig. 128, 
which is not advisable, or in monolithic form as shown in Figs. 126 



and 127. A design very successful in this respect is used by the 
New York Municipal Railway Corporation of Brooklyn, N. Y., on 
several of its elevated lines (see Fig. 126). 

Waterproofing on the concrete roadbeds over the mezzanine floors 
of these stations consists of a 2-ply membrane composed of treated 
cotton fabric and asphalt binder, applied over the concrete and lapped 
on to the steel girders. Sometimes the ends of the membrane were 

Surface of Concrete: 
At Stiffener Angles 
Between Stiffener Angles 

4 Lap of Membrane 
Construction Joint 
Reinforcing Rods 
Stiffener Angle 



FIG. 127. Section of Girder of Railroad Viaduct Showing Membrane Water- 
proofing, Protective Concrete, and Drip Channel. 

put into V-joints between the concrete and steel webs; these joints 
were then filled with an adhesive, elastic, bituminous compound. 
Over this membrane was placed a minimum of 4 inches of protective 
concrete. This concrete is brought up the sides of the girders to the 
top flange in monolithic form. This trough-type construction of 
track floors has proved very succeesful. A design even more efficient 
than the above one, from the waterproofing standpoint, is shown 
in Fig. 127. In this design a dripping surface is provided by the 



substitution of a steel channel for one of the cover plates of the steel 
girder. Fig. 128 shows the design of a steel and concrete roadbed 
on a few railroad viaducts in New York City. The waterproofing 
details, one of which is shown in Fig. 129, were not entirely 

In connection with the design and construction of watertight steel 
and concrete road beds of railroad viaducts it is proper to point out 
to the engineer whose duty it is to design the waterproofing for such 
locations that he would do well to carefully study the details connected 
therewith. He knows, for instance, that the structure is subject to 

3x2 Sleepers Platform 

2 Board 
^"Expansion Bolta 
2"x 12 "Lumber 

a Rods 1 6 Ctrs. 

Mezzanine Floor , 

3' Finish^ 

a Rods 6 Ctrs. 

y>"a Rods i 6' Ctrs. 

FIG. 128. Typical Construction , of Mezzanine Roof on Elevated Railroad 
Structures in New York City, Showing Location and Protection of Mem- 
brane Waterproofing. 

severe vibration; he should know, also, that a comparatively thin 
layer of concrete or mortar is almost useless for the protection of 
waterproofing under such conditions. He probably knows that only 
the membrane or perhaps the surface-coating types of waterproofing 
are serviceable for such a structure, but he should know also that 
joints between steel and concrete can remain watertight only so long 
as the joint filler remains plastic, though even this is doubtful, in view 
of the difficulties experienced in the design lastly referred to. 

Still another feature peculiar to such structures, as shown in Fig. 
128, would be revealed by a careful study of details and that is, that 


openings, large and small, crevices and pockets in the joints and 
connections of the steel members which cannot be filled or covered 
with the bed concrete, require calking. Or else the waterproofing 
must be carried up the sides of the steel work, suitably protected 
and high enough to effectually prevent the percolation of water 
through the joints and connections. Unless either of these things is 
done no amount or quality of waterproofing of the roadbed proper 
will make the structure watertight. 

The following is a case in point that has been brought to the 
attention of the author and well illustrates the need for careful 
study of waterproofing details. Fig. 128 is a cross-section through a 
steel viaduct where a mezzanine floor, roadbed, and elevated plat- 
form are shown. 

The purpose of the concrete roadbed is to form a solid roof 
protection for the structure underneath, and the concrete of the ele- 
vated platform serves a like purpose. Now, it is rightly assumed by 
the engineer that the concrete may crack in the course of time and 
allow water to seep through to the mezzanine floor below. To 
obviate this danger he specifies a 3-ply membrane to be laid on the 
concrete, and covered with a 4-inch protective coat of concrete. 
Realizing that the protective concrete cannot make a watertight 
joint with the webs of the girders or beams, the concrete covering 
is designed so as to leave a V-shaped joint between it and the steel, 
as shown in Fig. 129. 

Even when a good elastic compound is used as a filler, the mate- 
rial cannot last for more than a few years and retain the properties 
requisite for waterproofing under this condition. Hence, sole reliance 
upon such a material to always effectively seal the joint, is unwar- 
ranted. Still more so is the use of a high melting-point bitumen, such 
as a hard coal-tar pitch or asphalt, because they become extremely 
brittle materials at temperatures but little below the ordinary. Al- 
most the first train that would cross the viaduct during cold weather 
would cause the pitch in the V-joints to crack and break away from 
one of the two surfaces, after which it would be useless as a means 
of preventing water from seeping through the joint or getting around 
and under the membrane. It is a fact that plastic joint fillers have 
actually failed in this regard; that is, the joints between the steel 
and the filler opened and nullified the value of the rest of the water- 
proofing. It is equally a fact that this result is inevitable, because 
of the varying rates of vibration between the structural materials 
when a train passes over the structure due to the relatively different 
inertia of the steel and the concrete. 





An arrangement that would prove more efficient, though somewhat 
costlier, is shown at A in Fig. 130. In this form of construction, the 
effective waterproofing of the structure, or rather, the making of 
watertight joints is practically independent of the joint filler. This 

-3-Ply Membrane 


3-Ply Membrane 

Mop concrete 
( under flashing 

FIG. 130. Improved Types of V-joints for Elevated Structures. 

form of construction may also be modified so as to have the angle iron 
act as a flashing instead of a joint, as shown at B in Fig. 130. A 
strip of thin sheet lead between the angle and web is recommended. 
An arrangement, whereby the angle iron is eliminated and a copper 
flashing substituted, is shown at C, Fig. 130. This desien is 



efficient than the above two, because if the joint filler should fail to 
act, it would still be almost impossible for water to get around the 
flashing and seep through the joint. This design, however, is costlier 
and requires great care when applying and soldering together the 
sections of the flashing and in the selection of the metal. In design- 
ing the protective concrete, it is often necessary and always advis- 
able to reinforce it with some form of wire mesh of which the trans- 
verse ends should be left projecting somewhat into the joint filler. 
Fig. 131 shows a way to utilize the protective concrete so as to secure 
watertightness in the track floor. Other methods will undoubtedly 


FIG. 131. Waterproofing Details around Ferrules at Drains, also Showing 
Increased Utility of Protective Concrete over Membrane on Mezzanine 
Track Floor of Elevated Structure. 

suggest themselves upon careful consideration of the conditions at 
hand. The purpose of this digression is merely to call attention to 
the need of studying waterproofing details and carefully selecting 
the materials. 

Perhaps the citation of another glaring instance of an ineffectual 
design and application of waterproofing will impress the architect, 
engineer and contractor with the serious consequences following a 
disregard of the need to study details and understand the selection 
of waterproofing materials. 

A very important station on one of the Brooklyn (New York) 
Elevated lines consists of a double-deck concrete structure built 
partly below ground surface. The ceiling above the platform of 
the lower deck is raised and forms the train platform of the upper 



deck. The track floors between the platforms of the upper deck are 
waterproofed with a 6-ply membrane made of treated jute fabric 
and coal-tar pitch having a melting-point of 120 deg. Fahr. by the 
cube-in- water method. This membrane terminates directly over 
the webs of the platform girders as shown at A, Fig. 132. These 
girders support concrete walls which, in turn, support the platform 
of the upper deck. The first summer after the station was com- 
pleted considerable quantities of the binder exuded through and all 
along the construction joints between this concrete and the top flange 
of these girders. 

u^=^ ^ 


10' ft" 


Upper Level 

1 . 

' Protective concrete 
placed Jon waterproofing 
before track was placed 

FIG. 132. Cross-section of Station Platform and Track Floor, Showing Scheme 
of Waterproofing Proposed and Used on a Sub-level Railroad Structure 
in New York City. 

The resulting defacement of the structure and injury to the water- 
proofing was, however, not due to a poor grade of material nor bad 
workmanship in the application of the waterproofing, but was entirely 
due to faulty design, as is evident from the figure, and the neglect 
to specify a binder of an asphaltic nature or a coal-tar pitch of at 
least 30 deg. Fahr. higher melting-point. That this precaution should 
have been taken follows from the fact that the station has a super- 
structure which is exposed to the elements and hence the concrete 
may easily acquire a temperature above 100 deg. Fahr. in the sum- 
mer time. 


Another point worth mentioning is that the purpose of the water- 
proofing membrane in this particular structure is such as hardly 
requires more than three plies, and the way this should have been 
applied is shown at B, in Fig. 132, which is self-explanatory. 

Waterproofing Reinforced Concrete Standpipes. In the design of 
reinforced concrete standpipes, engineers have hitherto met with 
little success in obtaining watertight tanks for several reasons: 

1. Because of insufficient attention to proper grading and 
proportioning of concrete aggregates. 

2. Imperfect design of expansion joints (see Fig. 45 for a suc- 
cessful type of expansion joint). 

3. Laxity in supervision and workmanship during construction. 

4. Insufficient attention to details. 

Nearly all standpipes are so conditioned during their use that the 
concrete, especially the lower portion of the standpipe, is subjected 
to varying stresses consequent upon changing heads of water. During 
this action the stresses in the reinforcement likewise vary, hindering 
the silting up of minute cracks that may have formed and which after 
a freezing season may become dangerously large. 

Hence, it may be concluded that any structure subject to so 
many different kinds of stresses as is a concrete standpipe is best 
made waterproof by the application of a bituminous membrane of 
from two to four plies of fabric or cotton drill applied on the inside, 
and covered with a coat of mortar J to 1 inch thick. This method 
obviates the need of extraordinary precautions in grading and super- 
vision, and it will also be found that the cost is no greater and results 
more certain than when using either the integral or self-densified 
system of waterproofing. This method has been followed in several 
instances with success. 

Waterproofing Floor of Pneumatic Caisson. To aid the engineer 
in his judgment and to avoid delay in the execution of the waterproof- 
ing work in hand, he will do well to resort to some practical field 
tests for the determination of the working properties of a material 
or method not heretofore used or not used under extraordinary 
conditions. A case in point is the following: Specification require- 
ments for waterproofing the floor of a pneumatic caisson used in 
connection with the construction of two tunnels under the East 
River connecting the William and Clark Streets subway between 
the boroughs of Manhattan and Brooklyn (see Fig. Ill) called for a 
" soft pitch which will soften at 32 deg. Fahr. and melt at about 
60 deg. Fahr. so that it can be spread without heating." Its use was 
intended for waterproofing under compressed air where the fumes 


of hot melted coal-tar pitch would be unbearable to the workmen and 
give rise to fire risks. But such a low melting-point coal-tar pitch 
is not a commonly used waterproofing material and must be made up 
specially, hence delay and increased cost may result. 

The compressed air chamber was under about 20 pounds pres- 
sure, and had an air temperature of about 75 deg. Fahr. After 
completion, the concrete floor and the waterproofing underneath 
would have a temperature about 20 deg. below this, with the result 
that the low melting-point pitch would exude from cracks or would 
tend to flow toward any hollow or other depression in the concrete 
and perhaps nullify the purpose of the waterproofing. To avoid 
this condition and still use coal-tar pitch, for pitch was the only 
material allowed under the specifications, a straight-run coal-tar 
pitch having a melting-point of about 120 deg. Fahr. by the cube- 
in-water method, was first tried; that is, it was heated to about 
325 deg. Fahr. or over, poured in small buckets and lowered into 
the caisson. But coal-tar pitch, when heated to a temperature 
of about 325 deg. Fahr. as was done in this instance, fumes offensively. 
A test, by the author, to determine the temperature at which fumes 
commence to be given off by the molten pitch showed that hardly 
any was given off until a temperature of about 225 deg. Fahr. was 
reached. Hence all that was required was not to heat the coal- 
tar pitch beyond this point and a regular, stock material could be 
used. After a single trial it was used in this manner very success- 
fully. However, in the case of another caisson under about 40 pounds 
pressure per square inch, the soft grade of pitch called for in the speci- 
fication was used (necessitated by the greater fire risk) and the work 
well accomplished. 

Waterproofing Steel Swimming Tank.* A swimming tank, 
30 by 60 feet in plan, and from 4 feet to 8J feet deep, situated between 
the 10th and llth floors of the Union League Club House in Chicago, 
was waterproofed by the application of a sheet-lead membrane and 
a felt membrane against the lead. Before applying the sheet-lead 
membrane the rivet heads on the inside of the girders forming the 
sides of the tank were flattened to J inch. Over the entire area 
1J inches of cement mortar was put on with a cement gun. Upon 
this mortar coat the sheet lead, weighing 4 pounds per square foot 
(about Te inch thick), was placed and tacked to wooden strips set 
in the mortar. All the joints were soldered. Then the felt membrane 
was applied, being bonded with coal-tar pitch, and covered with 4 
inches of cement mortar also put on with the cement gun. The entire 
* Engineering Record, Vol. 75, No. 3, January 20, 1917, p. 107. 


inside was then lined with ceramic tile J inch thick, set in cement 

The above scheme, suggested by the contractor, and which 
proved very satisfactory, was substituted for the original specifica- 
tion calling for membrane waterproofing with calking and welding 
of joints to make the steel watertight. 


Waterproofing Roadbed Over Mezzanine. Some of the track 
floors over the station mezzanines on an elevated railroad in Brooklyn, 
New York, consist of a framework of steel beams and girders with 
concrete slabs in the open spaces, forming a series of bays (similar 
to Figs. 128 and 129). These bays are waterproofed with a mastic 
sheet approximately 2 inches in thickness placed directly on the 
concrete. Each bay is drained by a pipe to the adjacent one until 
the water reaches an end but central bay, from which it passes into 
a copper gutter. The drains are 3-inch wrought-iron pipes, 12 inches 
long, passing through the steel webs to which they are fastened by 
means of ferrules and made to adhere to the mastic. 

Before the mastic was applied to the concrete slabs, 2-inch strips 
of the steel webs were mopped at the required elevation with asphalt 
to secure a good bond between both. The mastic consisted of 
approximately 12 per cent asphalt, 14 per cent sand, 22 per cent 
grit, and 52 per cent limestone dust. 

Though the mastic was well made and applied, and was in good 
condition more than a year after application, it gave very poor 
waterproofing results. This was directly traceable to the poor bond 
between the steel webs and the mastic, being broken by the severe 
vibration in the structure and especially the non-synchronous 
vibration between the concrete slabs and the steel framework. 

The Dual Subway of New York City. In waterproofing the new 
subways in New York City two systems were used. The membrane 
(described under examples of membrane applications) and the 
brick-in-mastic envelope (described below). The latter method was 
used in the manner noted in detail, in Table XXI and illustrated in 
Fig. 1324. 

The floor and side walls of the subway below ground or mean high 
water, when passing through earth, also the roof of stations, were 
waterproofed by the brick-in-mastic system. This consisted of 
one or two courses of ordinary building brick embedded in mastic. 
The mastic was composed of a minimum of one-third asphalt and 



two-thirds sand and cement, or sand and limestone dust. It was 
mixed hot on the work in round-bottom iron kettles of 50- and 100- 
gallon capacities (see Fig. 77) at a temperature not exceeding 375 
deg. Fahr. 

IPlvWP One or more "Layers of 4 Concrete 2 Layers of Brick in Asphalt i ply W P 

'_ ', ' / Brick in A&phalt .;/ | | V / / !_, ' j 

2 Min. 


3 Ply W. P. i 4 Concrete 


4 Concrete 2 Layers of Brick in Asphalt j p\ y w.P. 


6 Concrete 

3 Concrete 


FIG. 132 A. 

In applying the brick-in-mastic to the floor of the subway, the 
surface of the concrete bed, which was generally from 4 to 6 inches 
thick, was covered with a single ply of waterproofing felt or fabric, 
and its surface completely mopped. This served as a dry ply upon 
which to place the brick-in-mastic envelope. 



Two courses of brick-in-mastic were applied to the floor and 
together had a minimum depth of 5 inches. The thickness of the 
various brick-coverings of mastic was not less than f of an inch 
(see Fig. 133). 

On side-wall construction, the vertical surface of the excavation 
was first carefully faced with concrete. Forms were placed 8 inches 

FIG. 133. Showing Application of First and Second Layers of Brick-in-Mastic 
and Method of Sliding Bricks into Place. (Note Mastic Covering Finished 
Portion between the Two Posts.) 

from this facing and the brick and mastic laid therein, as follows. 
A quantity of mastic was poured into the space and bricks laid in 
it on their largest bed and in a double row, leaving a minimum of 
f-inch joints around all faces. After cooling, the forms were removed 
and the main concrete wall of the subway was built against the mastic 
wall. No leaks developed where the brick-in-mastic envelope was 



Waterproofing Reinforced Concrete Reservoir.* In renovating 
a 1,000,000-gallon reinforced concrete reservoir at New Ulm, Minn., 
watertightness was secured in the structure by exercising special 
care during construction to grade the concrete aggregate. Pebbles, 
varying in size from J to 2J inches screened from a gravel bank, were 
used in the floor and walls, as experiments had shown that these 
pebbles made a denser concrete than broken stone. To reduce the 
permeability of the concrete to a minimum, however, 20 pounds of 
hydrated lime was used to every barrel of cement. After the forms 
were removed, the walls were brushed and cleaned with steel brushes, 
and two coats of 1 : 2 cement mortar, about | inch thick, water- 
proofed by the addition of 10 per cent of finely powdered iron, were 
applied. The floor was treated with a slush coat of 1 : 2 mortar 
which after setting received a brush coating of waterproofed mortar. 
After water was let in some leaking took place and cracks developed 
which were finally remedied and the reservoir was rendered watertight. 

Concrete Tank at Duxbury, Mass. A reinforced concrete tank 
in Duxbury, Mass., f 40 feet inside diameter and 35 feet high was 
made watertight by using a rich* concrete with an addition of hydrated 
lime. The bottom is a reinforced concrete slab built in two 12-inch 
layers, the lower one of 1:2:4 concrete and the upper one of 
1 : 1J : 3 mixture with the addition of 5 per cent hydrated lime. 
The walls are of 1 : 1 : 2 concrete with 5 per cent of cement replaced 
with hydrated lime, and the dome is of 1 : 2 : 4 concrete. In order 
to prevent water from passing through the joints made by each day's 
work, thin steel bands 4 inches in width were inserted so that one- 
half of the width was embedded in the old work and one-half in the 


Reinforced Concrete Filter Plant. In the construction of the 
filter plant at Lancaster, Pa., in 1905, a pure-water basin and several 
circular tanks were constructed of reinforced concrete. The pure- 
water basin is 100 feet wide by 200 feet long and 14 feet deep, with 
buttresses spaced 12 feet 6 inches center to center. The walls at 
the bottom are 15 inches thick, and 12 inches thick at the top. Four 
circular tanks are 50 feet in diameter and 10 feet high, and eight 

* Engineering Record, December 17, 1910, Vol. 62, No. 25. 
t Engineering News, Vol. 75, May 6, 1916. 


tanks are 10 feet in diameter and 10 feet high. The walls are 10 
inches thick at the bottom and 6 inches at the top. A wet mixture 
of 1 part cement, 3 parts sand, and 5 parts stone was used. No 
waterproofing material was used in the construction of the tanks, and 
when tested, two of them were found to be watertight, the other two 
had a few leaks where wires, which had been used to hold the forms 
together, had pulled out when the forms were taken down. These 
holes were stopped up and no further trouble was experienced. In 
constructing the floor of the pure-water basin a thin layer of asphalt 
was used, but no waterproofing material was used in the walls, and 
both were found to be watertight. 

Reinforced Concrete Watertank. A reinforced concrete water- 
tank, 10 feet inside diameter and 43 feet high, designed and con- 
structed by W. B. Fuller at Little Falls, N. J., has some remarkable 
construction features. It is 15 inches thick at the bottom and 
10 inches thick at the top. The tank was built in eight hours, and 
is a perfect monolith, all concrete being dropped from the top, 
or 43 feet at the beginning of the work. The concrete was mixed 
very wet, the mixture being 1 part cement, 3 parts sand, and 7 parts 
broken stone. No plastering or waterproofing of any kind was used, 
but the tank was found to be absolutely watertight. The large 
aggregate was, however, scientifically graded. 


Waterproofing Pressure Tunnels. Some of the tunnels of the 
Catskill Aqueduct of New York City * were made watertight by 
grouting behind the tunnel lining. This grouting followed the con- 
creting within a period of two to three months, when the concrete 
had attained sufficient strength to resist high grouting pressures. 
Air-stirring, grouting machines of the Canniff type, holding about 
25 gallons, were generally employed for this work, though a few 
mechanically stirred Cockburn machines of the same capacity were 
tried. For low-pressure work, by which the voids about the lining 
were filled, air direct from the compressor plants was used; for the 
high-pressure work the air pressure was raised by means of auxiliary 
high-pressure air compressors. 

For filling the voids in the dry packing and the cavities and 

shrinkage spaces left over the arch concrete, the grout was mixed 

in the proportion of one cement to one sand, with an equal volume of 

water, and forced in under pressure of 80 to 100 pounds or more 

* Engineering News, Vol. 73, February 4, 1915. 


per square inch, depending on the ground-water head. Neat cement 
was employed in filling the drip pans and other thin cavities. See 
Fig. 134 for details. No masonry cutoff walls were built to stop 
the grout, except where dry packing was to be filled, and no attempt 
was then made to make them tight at the crown of the arch. Work 
was started at some favorable point where the grout would of itself 
make a cutoff and carried steadily on, connecting to each pipe in 
turn. The general practice was to commence grouting through the 
pipes nearest the invert, and upward to the arch. On completion 
of the low-pressure grouting, neat-cement grout, generally mixed 
in the proportion of four to eight volumes of water to one of cement, 
though sometimes containing as much as fifteen volumes of water 
to one of cement, was forced into many of the pipes previously grouted 
and into the deep-seated pipes, under pressures of 250 to 3'00 pounds 
per square inch, to fill the small spaces and seams in the rock about 
the lining. The cost of grouting the tunnels to watertightness ran 
from $2.50 to $3 per lineal foot of tunnel, including the costs for plant, 
materials and labor. The tunnel was made remarkably watertight 
as a result of these operations. 

Ashokan Dam CutofL* In making watertight the cutoff wall for 
the Ashokan Dam on the Catskill Aqueduct, a row of 3-inch grouting 
holes were drilled 20 feet below the bottom of the trench, reaching 
the greatest depth at which the boring tests had indicated the 
presence of seams. Similar grouting holes were drilled to about 
the depth of the cutoff to insure the sealing of any seams that might 
exist in the rock under the main body of the dam. Two-inch iron 
pipes were cemented in the tops of the drill holes and carried up into 
the masonry to permit grouting when the dam had reached sufficient 
height to withstand the pressure of the grout. These grout pipes 
were then grouted with neat-cement by the use of a Cockburn Bar- 
row grout machine of 4 cubic feet capacity, operated under a pres- 
sure of 25 to 80 pounds. The results were entirely satisfactory. 

Rondout Pressure Tunnel. In constructing the Rondout Pres- 
sure Tunnel of the Catskill Aqueduct, several wide shafts were sunk. 
These shafts had to be waterproofed to facilitate operations; espe- 
cially one shaft in which the seams were large and many. Twenty- 
seven vertical holes were drilled, 14 to 20 feet deep and capped with 
pipes and valves for the purpose of grouting these seams. A battery 
of 4 Canniff tank-grouting machines were set up at the top with 
2^ -inch pipe in the shaft and a 2-inch hose connection at the bottom. 
At first the grout leaked back into the shaft in considerable volume. 

* " Catskill Water Supply of New York City," by Lazarus White, C. E. 




Various methods were then tried to prevent this leakage the use 
of oats, bran, and ground horse manure, the latter finally clogging 
the seams and stopping most of the leakage in the shaft. The 
shallower holes took 2900 bags of cement and the 20-foot holes only 
60 bags. This grouting proved to be so successful that it was deter- 
mined to grout some of the deeper seams known to be porous and 


Harlem River Tunnels. The use of cast-iron, cast-steel, and 
iron and steel plates for waterproofing is not common but none the 
less quite practicable. Fig. 135 shows half-sections through the 
steel lining used as waterproofing for the Harlem River Tunnel 
tubes connecting the Lexington Avenue subway between Manhattan 
and Bronx boroughs, forming a part of the Dual Subway System in 
New York City. The steel (Fig. 135^4.) was sunk in a prepared 
channel in the river bed and surrounded with concrete within and 
without. This created an excellent watertight tunnel.* The same 
is quite true of the cast-iron and cast-steel tunnel linings used on 
the Pennsylvania railroad tunnels under the Hudson River and the 
New York Subway tunnels under the East River. See Fig. 136 for 
details of the type of cast-steel tunnel segments used on the two 
latter structures. 

These segmental linings make an effective waterproofing, though 
the joints are not absolutely watertight. The leakage, however, 
is insignificant, as proven by the following fact. In the above- 
named tunnels, a sump of some form is provided at the lowest point 
of each tunnel or pair of tunnels and pumped out when necessary 
by pumps regularly installed. This showed that the daily leakage 
into the 5J miles of river tunnels of the Pennsylvania Railroad is 
2300 gallons. The magnitude of this may be better appreciated by 
stating that the entire amount of leakage for one day would be 
removed in one or two minutes by a pump of the capacity ordinarily 
used by contractors for foundations.! 

Rubber Sheet used on Waterworks Reservoir, t A reservoir 
built in Bellaire, Ohio, in 1905, was put into successful operation 

* See paper by Howard B. Gates, " Harlem River Crossing of the Lexington 
Avenue Subway." The Municipal Engineers Society's Journal, Vol. 1, No. 6, 
New York City, December, 1915. 

t Alfred Noble, in Journal of the Franklin Institute, Vol 175, p. 383. 

t Engineering Record, June 3, 1916. 




about this line 


FIG. 135. Harlem River Tunnel Tubes, as Built. 


for the first time in eleven years after its construction. This was 
made possible only after it was waterproofed by a unique method. 
Unstable foundations had caused cracks, particularly in one corner 
of the reservoir, which defied all the many attempts to make the 
structure watertight until the following inexpensive method was used. 
A strip of sheet rubber, stretching 30 feet long by 3 feet wide by 
| inch thick, was placed in the corner of the basin covering the crack. 
A box, built around this rubber-covering and filled with soft mud, 
kept the sheet in place. Another large crack, in the bottom of the 

FIG. 135A. Steel Tubes for Harlem River Tunnel, Lexington Avenue Subway, 

before Sinking. 

basin, was also covered with a strip of rubber and held in place by a 
cement mortar covering. The basin was then filled with water, and 
it was found that, although the crack in the wall opened YQ mcn 
still further, there was no leakage. This method was suggested and 
carried into effect by Mr. F. J. Lewis, a resident of Bellaire. 

Timber Sheeting Waterproofing for Subaqueous Tunnels.* 
Referring to Fig. 137, in which timber sheeting constitutes the 
waterproofing for a subaqueous tunnel, the author believes that if 
the form of tunnel construction indicated is at all practicable, the 

* Proceedings of the American Society of Civil Engineers for November, 1914. 





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proposed waterproofing method seems impracticable. To build a 
subaqueous tunnel and to waterproof it with creosoted, tongued 
and grooved yellow pine planking, pinned on the outside of the struc- 
tural material is a unique conception, though never attempted, to 
the author's knowledge. This form of waterproofing and its applica- 
tion, Mr. D. D. McBean, the originator, believes will be possible by 
the use of his patented " Subaqueous Working Chamber " for con- 
structing the tunnel. 

Basement Waterproofed with Sheet Lead Lining. The excava- 
tion for the basement of the Proctor & Gamble Mfg. Co.'s building on 
Staten Island, N. Y., was made in red clay. Due to the existence of 
swampy ground on the site, considerable seepage had to be contended 
against and prevented from percolating into the cellar. The floor 
and walls were built of concrete, and were waterproofed by the 
application on the inside of 1-ply sheet lead weighing 3 pounds per 
square foot. This sheet lead was also applied to the columns, the 
strips being carefully soldered together so as to make a seamless pan 
of the whole. On the floor the sheet lead was laid on a 1-inch sand 
cushion, and on the wall, directly against the concrete. The entire 
lead membrane was then protected with a 5-inch layer of concrete. 
The results obtained by this method of waterproofing were quite 

Cement-clay Cover for Hudson and Manhattan Railroad Tunnel. 
A waterproofing method, in which an impervious layer of cement 
and clay was interposed between water-bearing ground and a concrete 
substructure, was used in the recent addition to the Pavonia Avenue 
station of the Hudson and Manhattan Railroad in Jersey City, N. J. 
The work consisted in excavating, by tunneling methods and sub- 
sequently lining with concrete, a station opening in a water-bearing 
stratum 200 feet from the Hudson River bulkhead line and 50 feet 
below mean sea lavel. It was imperative that the concrete lining 
be watertight, but it had been the experience of the engineers in 
building the original tunnel that it was impossible in working under 
air pressure to use any applied waterproofing mats on account of the 
danger to workmen from fumes; expected expansion and contrac- 
tion with consequent cracks forbade the use of any integral water- 
proofing material. 

It had been noted that all of the river tunnels which rest in 
river clay were quite watertight, and it was believed that if a com- 
plete coating of clay could be obtained exterior to the tunnel lining, 
no more nearly perfect or complete waterproofing could be secured. 
The difficulty with any clay application was that when wet and soft 


the clay would change its form by squeezing. Therefore, experi- 
ments were made' with clay mixed with sufficient Portland cement 
to hold its form when set. 

Hudson River silt, which is a finely pulverized clay with a con- 
siderably larger proportion of silica than ordinary clay, was dried 
and mixed with equal proportions of Portland cement, applied through 
the medium of a cement gun as a heavy coating on every portion of 
exposed timbering and lagging in the tunnel. This produced a layer 
of impervious plaster about 2 inches thick against which the con- 
crete lining of the tunnel was placed. The method has proved suc- 
cessful, the station structure being practically dry under an extreme 
head of salt water. 

Iron-lined Coal Pits.* In constructing concrete coal pits for 
railway coaling stations of the elevator type it is essential that the 
pit (for the elevator bucket) should be watertight. The pit is 
usually considerably below the ground-water level and is subject to 
pressure, and when once put in operation it is a matter of difficulty 
and expense to get at it and make repairs. 

A plan, which has been used with success, is to place within the 
concrete a steel boot or tank with joints soldered in the field. A 
6-inch thickness of concrete is placed first, and then the steel boot 
is set in position and the sections soldered. When this has beon 
made watertight it is lined with 6 inches of concrete. All attach- 
ments, bolts ladders, etc., are set in this inner lining. 

Fig. 138 shows such a pit having a boot 6 feet 11 inches by 11 
feet 6 inches and a height of 11 feet, its top being above ground- 
water level. It is made of No. 20 galvanized iron, and the expecta- 
tion is that if the metal should rust in course of time it would still 
form a waterproof diaphragm by combination with the cement. 
The concrete is a 1 : 5 mix, made with gravel, and mixed moderately 
wet. The use of a similar boot composed of burlap and asphaltic 
composition has given fair success. To place a waterproof lining 
outside of the concrete would involve greater excavation and addi- 
tional form work. 

Calking Tunnels of Pennsylvania Railroad, f In making water- 
tight the East River Tunnels of the Pennsylvania Railroad, the joints 
between the cast-steel segments composing the tunnel rings were at 
first calked with a mixture of iron filings and salammoniac in the 
proportions by weight of 400 to 1. The calking was done by hand. 

* Engineering News, Vol. 76, October 5, 1916. 

t " The Subways and Tunnels of New York," by G. H. Gilbert, L. I. Wight- 
man and W. L. Saunders, 



Later, lead wool, calked cold by pneumatic hammers, was substituted 
with better results. This calking preceded the placing of a concrete 
lining about 1 foot thick inside the iron rings. One-to-one grout 
was then forced between the top of this inner concrete lining and the 
outer iron segments. Great care was exercised in this work and very 
good results were obtained. 

Waterproofing of the North River Tunnels of the Pennsylvania 
Railroad consisted in forming a rust joint (with a mixture of sal- 

Coal Car Track 

FIG. 138. Concrete Coal Pit Waterproofed with Sheet Steel Boot. 

ammoniac and iron borings) between the plates of the metal lining 
forming the tubes, and in taking out each bolt and placing around 
the shank under the washer at each end a grommet made of yarn 
soaked in red lead. Before calking with the rust mixture the joints 
were cleaned. The usual mixture for the joints was 2 pounds of 
salammoniac, 1 pound of sulphur and 250 pounds of iron filings or 
borings. Air hammers were used with advantage in calking this 
mixture into the joints. The results were variable and not always 




Importance of Accurate Estimates. Record costs do not always 
agree with the estimates given for any particular work because anal- 
ysis for systematizing labor operations preceding the making of such 
estimates are too often insufficient, or neglected altogether. This is 
illustrated by the enormous variations in bids received from contrac- 
tors for the same job. For example, the bids received for waterproof- 
ing a section of the New York Dual Subway in 1915 were as follows: 





' E.' 


(Per cent). 

Fabric membrane, 1-ply 








Fabric membrane, 3-ply 

Fabric membrane, 6-ply 

Brick-in-mastic, cu. yd 
Protective concrete, cu. yd 

On another section of the same subway, the following bids for 
waterproofing work were received: 







Fabric membrane, 1-ply 









Fabric membrane 3-ply 

Fabric membrane 6-ply 

Brick-in-mastic cu yd 

Protective concrete, cu. yd : . . 

To account for such marked differences in estimate figures several 
items enter into consideration; usually and mainly, these are the 
result of a wrong estimate of labor cost. The methods of manage- 
ment undoubtedly affect the cost to a very large extent, but this 
hardly explains the difference of 100 and 140 per cent in the esti- 
mated costs submitted by the different contractors. The variations 



are more probably due to the following four causes: (1) Inaccurate 
estimate of volumes or cost of materials; (2) inaccurate estimates 
of overhead costs and profits; (3) manipulation of estimate prices; 
(4) inaccurate estimates of labor costs. Material costs usually are 
figured without difficulty, and these, except during abnormal busi- 
ness conditions, are reasonably constant. Hence, only mistakes are 
chargeable here. The variation in overhead charges by two different 
estimators may be large because many contractors do not properly 
charge or divide their overhead items, but this difference on any one 
job cannot account for more than 15 or 20 per cent. Manipulation 
of estimate prices, that is, figuring high on one item and low on an- 
other, unless done with great skill and foresight, proves a profitless 
process so often that it is not generally resorted to. This would, 
however, in some cases, account for about 50 per cent of the varia- 
tion. Obviously, then, the big variations must be in the estimated 
labor cost. And this indeed is the item on which money is usually 
made or lost in contracting. 

Accurate Estimates Dependent on Accurate Methods. Accurate 
estimates by architects, engineers, and contractors should be made 
a matter of careful study. An appreciable saving would always 
result in the substitution of accurate methods for guesswork in esti- 
mating., Mr. Sanford E. Thompson, Consulting Engineer,* makes 
the following remarks in regard to the reduction of general construc- 
tion costs, which are also applicable to waterproofing costs. 

" Accurate cost keeping is of value in following up construction 
costs from day to day, in showing up waste labor and in providing 
a mark for the attainment of superintendents and foremen. Unless 
cost knowledge is in the form of small units, such comparisons cannot 
be made satisfactorily. 

'' To get the full benefit of a knowledge of unit costs, and in fact 
for this the knowledge must be even more thorough and include the 
unit times of performing the various operations, it must be utilized 
in the planning of the work in advance and in distributing materials 
and jobs; in selecting materials and methods which will result in 
lower labor costs; in adapting the construction plant to the special 
conditions; and, carried to its ultimate end, in laying out jobs for 
the workmen and giving them a reward for accomplishment. 

" Such management as this involves the adoption of factory 
methods in construction. Already the need of this is being recog- 
nized, but only to a limited degree. 

"Full economy in construction, however, will only be attained 
* Engineering and Contracting, March 1, 1916, p. 221. 


as the builder discards the haphazard rule-of -thumb method and con- 
siders his job with a view to thorough analysis, planning functional 
methods, and a complete study of details. By such methods as 
these will the labor of construction be brought to a more scientific 
basis and more nearly on a par with the material end of the work." 


Waterproofing Labor, Contracters and Manufacturers Graded. 
Among waterproofing concerns there are to be found the following 
classes: (1) Waterproofing manufacturers who manufacture and 
assume responsibility for the quality and effectiveness of the water- 
proofing material; (2) Manufacturing waterproof ers who manu- 
facture and apply the waterproofing material under a guarantee; 
(3) waterproofing contractors who buy the waterproofing material 
ready made, supply the labor, and supervise and guarantee the 
work; (4) waterproofing subcontractors who often are furnished 
with the waterproofing materials, but always supply the labor, and 
give personal supervision to the work. 

Some of the concerns included under the above classes are not 
sufficiently responsible or experienced, hence it is often advisable to 
employ an experienced waterproofing inspector on the work, espe- 
cially when the magnitude of the work warrants the expense. Where 
this is not the case, experience has proven the advisability of con- 
tracting for the waterproofing work with a reputable and highly 
responsible waterproofing concern but always under a very specific 

Many waterproofing concerns maintain laboratories and staffs 
of engineers who co-operate with the contractor, or builder, in deter- 
mining the proper system and materials for waterproofing a particu- 
lar structure. The service is often given gratis. In consequence, 
the advice, or information, is not always impartial, and it seems 
advisable that the buyer, builder, architect, or engineer, should 
investigate somewhat for himself. The result may not only be an 
improved design but often a reduction in the cost of waterproofing 
the structure. 

The labor employed on waterproofing work is also divided into 
several classes, as follows: (1) Foremen, who are men generally of 
large experience in waterproofing work; (2) Waterproof ers, men who 
do the actual waterproofing work, such as laying the brick and 
mastic courses, sheet mastic, or applying bituminous membranes; 
(3) helpers, men who help the waterproofers and incidentally learn 
the trade; (4) Kettlemen, men who tend the kettles in which the 
bitumen is heated or the mastic is made up; (5) laborers, men who 


carry the bricks, wood, etc., to the waterproof ers and kettlemen, 
and perform all the unskilled labor required; (6) roofers, men who 
mainly waterproof roofs of buildings; (7) roofers' helpers, men who 
assist the roofers. In none of these divisions is any extraordinary 
skill required. Indeed, in the application of all waterproofing care 
and judgment are mostly required. 

It is not necessary to employ men of a particular trade to do water- 
proofing of a particular kind, but it is very essential to employ men 
with some experience in the particular branch of waterproofing. 
For example, in waterproofing a structure by the application of a 
brick-in-mastic envelope, it is not necessary to employ a bricklayer 
for this purpose, because no special bond of brick, nor refinement of 
line is required, as in building construction; but experience in hand- 
ling mastic and properly laying up mastic courses is necessary for 
good results. This, however, can often be done by the average 
waterproof er after a short apprenticeship. Besides, the difference 
in wages between bricklayers and waterproofers would materially 
affect the contract price of a particular waterproofing job. 

The general cost of waterproofing labor depends to a certain 
extent upon the locality of the work, the nationality of the workmen, 
but more particularly, of course, upon the character of the work 


The cost of most standard waterproofing materials, like other 
building materials, fluctuates with the market. The cost of patented 
or special waterproofing materials depends generally on the quantity 

In buying waterproofing materials, it should be the aim of those 
responsible, to buy materials that are either well-known or of proven 
efficiency because in the end they prove to be the cheapest. Some 
concerns make a practice of renaming standard materials and selling 
them at vastly inflated prices. It is no simple matter to guard against 
this, but when large quantities of waterproofing materials are to be 
bought, it will pay those concerned to look into the standard materials 
on the market before buying any special ones. This has particular 
reference to materials used in the surface coating and integral 
systems of waterproofing, and joint-filling compounds. 

In the following tables will be found the cost of waterproofing 
materials, labor, and implements for the year 1914. These tables 
are compiled with more than approximate exactness. Certain other 
information is included which will be found helpful in estimating 
and ordering materials. For the duration of the present (1918) 



abnormal status of commerce, the cost and price figures given in 
the tables should be doubled. 

Table XXII gives the average wages, during 1914, of the differ- 
ent classes of workers employed in the waterproofing industry and 
their range includes eastern and western standards of wages. The 
lower figures usually represent the western scale. 

Table XXIII gives the cost and weight of waterproofing imple- 
ments and tools and some of the manufacturers who specialize in 
these. The variation and range in cost of each article is mainly 
due to the difference in size of the articles. 

Table XXIV gives the selling price at New York and weight of 
the most important and most extensively used waterproofing 
materials. The variation in prices is due to the fact that they in- 
clude the cost of handling, trucking, etc., except the freight rate, 
which is too variable. 

Table XXV shows the cost of different types of waterproofing 
applied. The profit to the waterproof er and roofer included in 
most of these figures ranges between 15 and 30 per cent. 

Table XXVI, " Cost of Tin for Flat and Standing Seam Roofing," 
enables the architect and roofer to calculate the cost of the roofing 
material from the cheapest to the dearest made tin plate. These 
prices depend on whether the base plate is iron or steel, and upon 
the thickness of the coating thereon. The coating consists of an 
alloy of tin and lead, and the weight of this coating, per box of 112 
sheets, is the governing factor in the cost. This weight varies from 
8 to 40 pounds. Those plates carrying less than 20 pounds are re- 
garded as the cheaper grade, while those carrying more are in the 
dearer grade. The weight of coating should be distinctly called 
for in any tin roofing specification, and also stamped on the tin 
sheets by the manufacturer. 


(!N 1914) ' 


Wage Per 



$4 00 to 5 00 

Municipal and priVate inspection 


4 25 to 5 00 

Waterproof ers 

3 . 50 to 4 . 50 

On construction work of New York 


2 . 00 to 2 . 50 

Rapid Transit Subways. Union 

Waterproofers' helpers . . '. 

1.75 to 2. 25 
1 50 to 2.00 

Unskilled labor. 


3 50 to 4 . 50 

Roofers' helpers 

2. 25 to 2. 50 


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Cement (Portland 

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board sheathing under 
erage conditions. 

D 1 C3 1 3 

48 "S 4, 

i i 51 ii 

o o "5*a a ~ 















When Tin 
(per Box.) 

Flat Seam 
per Square). 

Standing Seam 
per Square). 

When Tin 
(per Box). 

Flat Seam 
per Square). 

Standing Seam 
per Square). 





























































*Price per 100 square feet at a given price per box of 112 sheets Cost of laying not 


Explanation of Tables. Tables are very useful, and in technical 
books indispensable, especially when they are all pertinent to the 
subject. A conscientious effort has been made to keep the present 
work free of the encumbrance of irrelevant tables. The few included 
herein have been found indispensable. They are believed to be 
accurate but not necessarily complete, though sufficient for all 
practical purposes. 

Table XXVII, " Thermometric Equivalents," converts the Fah- 
renheit temperature scale into the Centigrade scale and vice versa. 
This is often necessary in the laboratory and in the field. 

Table XXVIII gives the relative values of density and specific 
gravity of liquids heavier than water. 

Table XXIX, " Specific Gravity and Baume for Liquids Lighter 
than Water," shows the relation of density, as recorded on the 
Baume scale, to specific gravity of liquids lighter than water. Every 
liquid lighter than water has a definite specific gravity at a certain 
temperature, and in consequence a definite density which is usually 
measured by the hydrometer and expressed on the Baume scale. 
Some liquids, such as petroleum oils, when distilled at and to a cer- 
tain temperature, give off volatile oils, which leave the residue denser 
than the original; this denser composition is indicated by a corre- 
spondingly higher reading on the Baume" scale. This reading may 
be transformed, by means of the table, into an equivalent specific 
gravity of that liquid for that temperature. 

Table XXX, " Specific Gravity and Coefficient of Expansion of 
Various Materials," is compiled from the most reliable sources. 
Some of the values are not to be found in any book, having been 
obtained from research laboratory tests. A knowledge of the rela- 
tive expansion and contraction of mineral and organic solids and 
liquids is often necessary in waterproofing engineering. 

Table XXXI, " Weight and Thickness of Burlap, Felt, and Cot- 
ton Fabric Membranes with Coal-tar Pitch Binder," is based on water- 
proofing membranes made only with coal-tar pitch binder. If 







-* <N 00 CO-* IN OOCO-^N OOCOTj<<N 00 CO * <N 00 CO ** <N 00 CO * <N 

-tlN 00 <O Tj <N 00 


IM (N 00 CO <** IM OOCO-*(N 00 CO TT< IN 00 O * <N 00 CD * (N 



IN iM<N IN <N < 

>OOOOOr^^'-^'--i'--i(N(N(N(N(N(NC 1 OCOOOC y 3COCOTf<Tj4Tf<Tf''tiiOiO 




OOCOrJON COCO^IN COCOON 00 CO * (N 00 CO ^ <N OO CO -*<N 00 CO -^ ( 

> t^ O I-H < 

^H rH ^H i-H ^H i-l IN IN <N IN <N CO 




Specific Gravities at - F. jW^C- Corresponding to Degrees Baume* for 
Liquids Heavier than Water 

Calculated from the formula, specific gravity F. 









































































































































































1 . 1077 


















1 . 1223 



1 . 1240 

1 . 1249 











1 . 1337 

1 . 1346 










1 . 1426 



1 . 1453 

1 . 1462 



1 . 1490 



1 . 1508 








1 . 1581 



1 . 1600 

1 . 1609 



1 . 1637 







1 . 1694 




1 . 1731 








1 . 1798 




1 . 1837 


1 . 1856 

1 . 1866 

1 . 1876 



1 . 1958 

1 . 1905 



1 . 1934 






1 . 1983 

1 . 1993 





























































































































1 3242 








f*f\o r~ 1 co p*/ -| 

Specific Gravities at ^ F. ' C. Corresponding to Degrees Baum6 for 
60 L15 .55 J 

Liquids Heavier than Water 

























































































































































1 . 5073 














































































































































































































































60 ri5 56 ~\ 
Specific Gravities at 5 F. ' C. Corresponding to Degrees Baume for 

Liquids Lighter than Water 

Calculated from the formula, specific gravity 3F. = 


Baum -J 














































































































































































































































































































































TABLE XXIX.C(mtinued 

Specific Gravities at - F. i- C. Corresponding to Degrees Baume* for 
oU |_lo. oo J 

Liquids Lighter than Water 













































































































































































































































































































































.7032 .7028 










TABLE XXIX. Continued 

60 n^ 'ifi ~\ 

Specific Gravities of F. - ' C. Corresponding to Degrees Baume for 

60 |_15. 56 J 

Liquids Lighter than Water 


























































































































































































































































































































































asphalt binder is to be used instead the weight of the membrane 
may be taken as 15 per cent less than the values given in the table. 

The weights and thicknesses noted in columns 3, 4 and 5, are 
average values of many specimens actually weighed and measured. 
The rest of the items were calculated. The two thicknesses of binder 
film, Y& mcn an d ^-inch were assumed because r^-inch is the thick- 
ness of a film of binder when carefully applied with a single mopping, 
while the ^-inch film is obtained with a double mopping which is 
sometimes called for on important work. Where the ^-inch thick- 
ness of film is used only half the number of plies required for the 
YQ inch would be necessary under the same conditions of water 
pressure, etc. 

While jute burlap weighing 7, 8, 9, 10 and even 11 ounces is some- 
times used, the 7J-ounce open-mesh variety is most extensively 
used. No. 26 felt is a very commonly used grade, though anywhere 
from No. 20 to No. 50 felts are used for membrane waterproofing. 
The heavier-weight felts are usually used for roofing. The medium- 
weight cotton fabrics are most extensively used for membrane water- 
proofing. These weights range from 4 to 6 ounces per square yard. 

For obtaining weights of complete membranes consisting of more 
than 6 plies, the simplest way is to draw a curve on cross-section 
paper for three or four values in which the number of plies are the 
abscissa and the weights are the ordinates. It will be found that 
the curves so drawn are straight lines and may be produced to give 
the values sought. 

Table XXXII, " Thickness of Waterproofing Materials for Dif- 
ferent Water Pressures," shows the approximate number of felt and 
fabric plies, thicknesses of mortar and mastic layers and the number 
of courses of various kinds of waterproofing materials (applicable 
to the membrane or surface-coating types of waterproofing), required 
under various heads of water. It is compiled from a careful study 
of the general field practice in waterproofing underground structures. 
The bituminous sheet mastic layers, the brick-in-mastic courses and 
the different membranes, should be protected, or rather, encased 
in masonry, both to support them and protect them from climatic 
temperature changes. The surface-mortar coats, J inch thick or 
less, must not be put on in several layers to make up there quired 
thickness, but the thicker mortar coats may have a scratch coat, 
and together with the " finish coat " should make up the required 
thickness. Both the thin and thick mortar coats must be applied 
continuously over or on the structure until completed. 

Table XXXIII, " Volumes and Weights of Ingredients used in 



Brick-in- (Asphalt) Mastic Waterproofing/' is based on present- 
day practice of laying common bricks in a bituminous mastic to 
form a thick waterproofing envelope about an underground structure. 
It is further based on the use of asphalt only for making the mastic, 
but coal-tar pitch can be used with practically equally good results. 
The weight of asphalt was assumed to be 66 pounds per cubic foot. 
The average weight of coal-tar pitch is 76 pounds per cubic foot. 

The size of joints between bricks in the brick-in-mastie envelope 
is of vital importance. Bricks laid close together, that is, without 
joints, vitiate the function of the waterproofing envelope. It is 
obvious that the bricks do not constitute a waterproofing medium 



at 62 F. 

ent of 
sion Per 
Deg. F. 


at 62 F. 

ent of 
Per Deg. 

Alcohol (100%) 


. 00058 



Asphalt, artificial (Eastern 

Brick (common) 
Brick masonry 


. 00000306 
. 0000031 

21 Baume 
Asphalt, Bermudez Lake. . 
Asphalt, Mexican 
Asphalt Trinidad Lake 


1.06 1 

. 00035 2 
. 00028S* 

Clay ''Dry lumps) 
CoL.._ete (stone) 



. 0000068 
. 0000093 

1 21 

00035 2 

Glass . 



Asphalt, Trinidad, liquid. . 


. 00030 3 

Granite (New Hamp.). 


. 0000047 
. 0000044 

China wood oil 
Caoutchouc (rubber) 

1 07 

. 000355 

Hydrated lime 
Iron (wrought) 


. 0000067 



Lime (slaked) 


Gutta Percha 


0000408 8 


2 65 



0003 80 7 

Mortar (1 2) 

1 84 


Paraffin (hard) 



Oak (white) .... 



Oils (vegetable) 


Pine (long leaf) 


. 0000030 

Oils (mineral) 
Petroleum, Mexican as- 
phaltic (crude) 


1 298 

. 000392 
000243 5 

Plaster (white) 
Portland cement (set) . . . 
Rubble masonry 

2 44 

. 0000092 
. 0000035 

Pitch oil tar 

1 218 

000258 6 



. 0000058 

1 1 




Rubber (sheet) 

1 5 

Terra Cotta 







000454 7 

Tin (rolled) 



Water (4 C ) 

1 000 


Zinc (rolled) . .... 


. 000017 



1 Specific gravity at 77 deg. Fahr. 

2 Asphalt having penetration between 0.50 and 0.75 cm. at 77 deg. Fahr. (100 grams, '. 
seconds). Coefficient between 77 and 300 deg. Fahr. 

3 Asphalt is for cold application. Coefficient between 77 and 100 deg. Fahr. 

4 Asphalt having penetration between 0.65 and 0.83 cm. at 77 deg. Fahr. 

6 Straight-run product having a melting-point of 137 deg. Fahr. by the cube-in-water 
method. Coefficient between 60 and 180 deg. Fahr. 

6 Melting point 160 deg. Fahr. by the cube-in-water method. Coefficient between 60 
and 180 deg. Fahr. 

Between 50 deg. and 100 deg. Fahr. 

At + 30 deg. Fahr., reducing to .0000197 at - 30 deg. Fahr. 





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g 7 oz.; henc 
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ong, weig 
tively, 0.5 

of the fabric. The volume of the open meshes 
r cent of the voids of the untreated jute burlap. 

=5.34 lb. 
lling the open mes 
cu. in., or about 40 

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in themselves, they merely furnish " body," depth and weight to 
the envelope and economy in the waterproofing system. The bitu- 
minous mastic alone is the waterproofing medium, hence the more 
of it present within economical limits, of course the better. The 
smallest joint should be not less than f inch and the largest need 
not be more than J inch. Therefore the volume and weight of the 
various ingredients have been calculated on this basis; also on the 
empirical basis of a 20 per cent and 30 per cent reduction in volume 
of mastic, as compared to volume of ingredients (see Chapter VII), 
mixed in proportions of 2 : 1 : 1 and 1 : 1 : 1, respectively. 









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* Each third ply to be either jute or cotton fabric. 

t Sheet mastic composed of 15 to 25 per cent of bitumen; sand, grit and cement or lime- 
stone dust in equal proportions. 

t Mastic (for brick and mastic) composed of 35 to 45 per cent of bitumen, and equal parts 
of sand and cement, or limestone dust. 

(a) Open-mesh variety. 

(6) Closed-mesh variety. 

(c) Bricks laid on 8 X3 inch face, on horizontal and against vertical surfaces. 

(rf) Bricks laid on 8X2 inch face, on horizontal surfaces, but on the 3Hnch face against 
vertical surfaces. 





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Table XXXIV, " Pressure Exerted by Water Beneath Floors 
and Against Walls," is based on the principles of hydrostatic pres- 
sure, which are, (1) the pressure on the base of a vessel containing 
water is equal to the height of water above the base, times its area; 
(2) the average water pressure on the side of a vessel is equal to 
one-half the height of the water in the vessel, times the area of the 
vertical surface in contact with the water; (3) the pressure of water 
is transmitted equally in all directions. The type of waterproofing 
is often governed by the water pressure it will have to resist as judged 
by the height of ground or mean high water level above the base of 
the structure to be waterproofed. The table converts this height 
into pounds pressure for each of the above three conditions. 


Hydrostatic Head 

per Square Inch 

Lifting Pressure 
per Square Foot 
(Under Floor) Lbs. 

Average Pressure 
per Square Foot on Wall 
Surface Affected. Lbs. 









































































Table XXXV, " Approximate Weight and Thickness of Various 
Sheet Metals for Roofings, Gutters and Flashings," gives the weight, 
thickness and gauge number of various sheet metals commonly used 
for gutters, flashings, and roofings. Sheet metal is usually designated 
by the weight of a superficial foot, in pounds or ounces, or by some 
standard gauge. All tin, iron and steel are figured on the U. S. 
Standard gauge; copper is figured on the Brown & Sharpe gauge; 



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zinc has a gauge of its own, while lead is usually figured at so many 
pounds to the square foot, such as 2-pound lead, 3-pound lead, etc. 
Galvanized sheets have a gauge based on their weights, and not on 
the thickness. Corrugated galvanized sheets usually figured on 
the U. S. Standard gauge, are made in standard widths of corru- 
gations, and in standard lengths, ranging from 5 to 10 feet, with 
a maximum length of 12 feet. 

Table XXXVI, "Weights of Roof Coverings," gives closely 
approximate weights of various roof coverings and sheathings. 
These figures are very useful for designing and estimating. 



Average Weight in 

Lbs. per Sq. Ft 

of Roof. 

Ash wood sheathing, 1-in. thick 5.0 

Asbestos shingles (laid French method) 2.8 

Asbestos shingles (laid American method) 4.0 

Chestnut wood sheathing, 1-in. thick 4.0 

Copper, 16 oz., standing seam 1.3 

Clay tiles (plain) 10 by 6i by f ins., 5 in. to the weather. . . 18.0 

Clay tiles (Spanish) 14 by 10 ins., 7i ins. to the weather. . . 8.5 

Felt and asphalt (3 plies) (without sheathing) 2.0 

Felt, asphalt and gravel (6 plies) (without sheathing) 8.0-10.0 

Glass, i-in. thick 1.8 

Hemlock sheathing, 1-in. thick 2.0 

Iron, corrugated, No. 16, B.W.G. (without sheathing) 3.6 

Iron, galvanized, flat No. 16, B.W.G. (without sheathing) .... 3.0 

Maple sheathing, 1-in. thick 4.0 

Oak sheathing, 1-in. thick 5.0 

Sheet iron, ^g-in. thick 3.0 

Sheet-lead, about i-in. thick 8.0 

Slag roofing (four-ply) 4.0 

Slate, |-in. thick 9.0 

Slate, fk-in. thick (double-lap) 6.8 

Slate, |-in. thick (3 in. double-lap) 4.5 

Spruce sheathing, 1-in. thick 2.5 

Terne plate (tin), 1C (without sheathing) 0.5 

Terne plate (tin), IX (without sheathing) 0.7 

Tiles, 2 in. to 4 in. thick (plain, with mortar) 15.0 

White pine sheathing, 1-in. thick 2.5 

Wood shingles, 6 by 18 ins., | to the weather 2.0 

Yellow pine sheathing, 1-in. thick 4.0 

Zinc No. 20, B.W.G 1.5 


Table XXXVII, "Square Feet Covered by 1000 Wooden 
Shingles," gives the covering capacity of a thousand wooden shingles 
of various lengths and widths, according to fractions exposed to the 
weather. The number of shingles per 100 square feet of roof surface 
can be easily calculated therefrom. In doing so about 5 per Cent 
should be added for hip roofs and about 10 per cent for irregular 
roofs with dormer windows. The number of nails required is usually 
about three times the number of shingles. 

Table XXXVIII, " Number of Slates and Pounds of Nails for 
Roofing," gives the number of slate shingles and quantity of nails 
required to cover 100 square feet of roof surface. These values are 
also applicable to flat, baked-clay tiles. 

Table XXXIX, "Size, Length, Gauge and Weight of Roofing 
Nails," will prove helpful to the roofer. Nails shorter than J inch 
are generally not used. Nails with large flat heads and barbed shanks 
are best for all roofing purposes. 


O ^ 








Width in Inches. 

Width in Inches. 


Width in Inches. 




































































..'. . 












(PER 100 SQ. FT.) 

Size of 

No. of Inches 
When Laid. 

No. per 
(100 Sq. Ft.). 

Weight of 
Galvanized Nails 
per Square. 

Lb. Oz. d. 








1 10 4 




1 12 4 




1 15 4 












1 13 3 
























32 3 








3 12 3 








4 93 








6 1 3 

* American Civil Engineers' Pocket Book, p. 404 (2d Edition). 



































O t, 





























































































































. . 

. . , 

. . 







* As manufactured by Pittsburgh Steel Co. 




MECHANICAL analysis consists in separating the particles or grains 
of a sample of any material, such as broken stone, gravel, sand or 
cement, into the various sizes of which it is composed, so that the 
material may be represented by a curve (see Figs. 139-140), each 
of whose ordinates is the percentage of the weight of the total sample 
which passes a sieve having holes of a diameter represented by the 
distance of this ordinate from the origin in the diagram. 

The objects of mechanical analysis curves as applied to concrete 
aggregates are (1) to show graphically the sizes and relative sizes 
of the particles; (2) to indicate what sized particles are needed to 
make the aggregate more nearly perfect and so enable the engineer 
to improve it by the addition or substitution of another material; 
and (3) to afford means for determining best proportions of differ- 
ent aggregates. 

To determine the relative sizes of the particles or grains of which 
a given sample of stone or sand is composed, the different sizes are 
separated from each other by screening the material through succes- 
sive sieves of increasing fineness. After sieving, the residue on each 
sieve is carefully weighed, and beginning with that which has passed 
the finest sieve, the weights are successively added, so that each 
sum will represent the total weight of the particles which have passed 
through a certain sieve. The sums thus obtained are expressed as 
percentages of the total weight of the sample and plotted upon a 
diagram with diameters of the particles as abscissae and percentages 
as crdinates. 

A convenient outfit for such a mechanical analysis as above 
described, consists of a set of sieves, an apparatus for shaking the 
sieves, and scales for weighing. A standard size of sieve is 8 inches 
in diameter and 2J inches high. Sieves with openings exceeding 
0.10 inch are preferably made of spun hard brass with circular 
* Taylor and Thompson " Concrete, Plain and Reinforced," p. 193. 




openings drilled to the exact dimensions required. Sieves with open- 
ings of 0. 10 inch and less are preferably of woven brass wire set into 
a hard brass frame. Woven brass sieves are made for many purposes, 
and are sold by numbers which are approximately the number of 
meshes to the linear inch. As the actual diameter of the hole varies 
with the gauge of wire used by different manufacturers, every set of 
sieves must be separately calibrated. 

The number and sizes of sieves to be used depends upon the im- 
portance of the testing to be done. A convenient set of sieves for 
ordinary laboratory practice is given below in Table XL. 


Stone Sieves, Diameter 
of Hole (Inches). 


Commercial No. 

Diameter in Inches. 



3 00 

1 in. round 
No. 7 




" 12 




" 20 




" 30 




" 50 




" 90 




" 200 



When many analyses are to be made, it is convenient to have a 
printed cross-section form, with appropriate spaces for filling in the 
number of the analysis, description of the material, location of the 
work, and other facts relating to the material. 

For those who are unfamiliar with mechanical analysis, a detailed 
explanation of the method of locating the curve is here given. The 
method can best be understood by referring to the diagrams of 
typical materials which are also of practical interest as illustrating 
the curves which may be expected in special cases. 

Fig. 139 represents a typical mechanical analysis of crusher-run 
micaceous quartz stone which has been run through a J-inch revolv- 
ing screen so as to separate particles finer than \ inch, that is, the 
dust for use with sand. 

For a sample of stone, which may be taken by the method of 
quartering * 1000 grams is a convenient quantity for 8-inch diameter 

* The method of quartering consists in taking shovelfuls of the material 
from various parts of the pile, mixed together and spread in a circle. The circle 
is quartered, as one would quarter a pie; two of the opposite quarters are shoveled 



sieves 2J inches in depth, and also permits of easy reduction from 
weights to percentages. To obtain the analysis shown in Fig. 139, 
the sample of stone is placed in the upper (coarsest) sieve of the nest 
of stone sieves given in Table XL, and after 1000 * shakes the nest 
is taken apart, and the quantity caught on each sieve is weighed, 
beginning with the finest and placing each successive residue on 
the scale pan with that already weighed. The results obtained in 
the particular case under consideration are illustrated in Table 
LXI, which shows the method of finding the percentages: 

55 o3 

ven Diameter 

s i 

2 2 o 3 o o' -< -H 










ercent, by Weight, Smaller than gi 

8 J 










v , " 

















0.75 1.00 1.25 

Diameters of Stone in Inches 




FIG. 139. Typical Mechanical Analysis Curve of Crusher-run Micaceous 

Quartz Stone. 

The various percentages are plotted on the diagram and the curve 
drawn through the points. The vertical distance from the bottom 
of the diagram to the curve, that is, the ordinate at any point, 
represents the percentage of the material which passed through a 
single sieve having holes of the diameter represented by this particu- 
lar ordinate. Since the percentage of material passing any sieve 
is always the complement of the percentage of grains coarser than 
that sieve, the vertical distances from the top of the diagram down to 
the curve represents the percentages which would be retained 

away from the rest, thoroughly mixed, spread, and quartered as before. The 
operation is repeated until the quantity is reduced to that required for the 

* In practice to-day the custom prevails of shaking the material until no 
more comes through as determined by successive weighings. 



upon each sieve if employed alone. For example, taking 1.25, 62 
per cent, the distance from the bottom of the diagram, represents 
the percentage of material finer than IJ-inch diameter, and 38 per cent, 
the distance down from the top of diagram, represents the percent- 
age coarser than 1J inch. 


FIG. 140 

Size Sieve. 

Amount Finer than 
Each Sieve. 

Percentage Finer 
than Each Sieve. 



Per Cent 























Typical curves of a fine, a medium well graded, and a coarse sand 
are shown in Fig. 140. For convenience in plotting, the horizontal 



0.075 0.100 0.125 

Diameters of Sand in Inches 




FIG. 140. Typical Mechanical Analyses Curves of Fine, Medium, Well-graded, 

and Coarse Sands. 

scale is ten times greater than that of Fig. 139, the diagram showing 
diameters ranging from to 0.200 inch diameter. 

The mechanical analysis of crusher dust is apt to vary between 
the curves of fine sand and medium sand which are shown in Fig. 140. 


REGARDING the chemical action of sea water on concrete and its 
prevention, the following information and conclusions are presented 
here because of their bearing on and corroboration of the subject 
matter of Chapter I.f 

Investigations concerning the effect of sea water on concrete 
immersed for periods up to fifty years or more; of the relative merits 
of standard Portland cement and Portland cement made with dif- 
ferent proportions of its principal constituents, in resisting the dis- 
integrating effect of sea water; of the effect of varying the propor- 
tions of cement in the mortar and concrete; of differently graded 
aggregates; of the addition of various finely ground materials to 
the cement after burning; of the relative durability of concrete 
cast in place as compared with concrete blocks allowed to harden 
before placing in the sea ; and of the effect of various materials added 
to the concrete mixture to produce impermeability and consequent 
increased durability, have been made in European countries and in 

Regarding the chemical action of sea water on cement, the fol- 
lowing conclusions are presented: 

Cement containing up to 2J per cent of sulphuric anhydride 
(SOs) resists the action of sea water fully as well as cement with lower 
sulphuric anhydride content. 

While all the hydraulic cements now in use are liable to decomposi- 
tion in sea water, Portland cement is the one to be preferred in every 

High iron Portland cement and puzzolan cement have failed to 
show superiority over standard Portland cement in resisting the 
disintegrating effect of sea water. 

* American Railway Engineering Association, Vol. 15, March, 1914, p. 564. 

t For a presentation of practical results of marine construction and valuable 
conclusions drawn from observed effects of sea water on concrete all over the 
United States, see five articles by Rudolph J. Wig and Lewis R. Ferguson in 
Engineering News-Record, commencing Vol. 79, No. 12, 1917. 



Regarding the effect of varying the proportions of cement in the 
mortar and concrete, in general, the richer mixtures have been found 
to offer better resistance to the attack of sea water. Proportions 
recommended for mortars are those with one part cement to one part 
of sand up to one part cement to two parts sand. The bad condi- 
tion of mortars leaner than the above after exposure in sea water, 
stands out prominently. 

In the use of reinforced concrete for maritime works, it is advis- 
able to employ larger proportions of cement than are usual for similar 
works in fresh water. 

Concerning the addition of finely ground material to the cement 
after burning, it has been found that the addition of ground puzzolan 
or furnace slag to Portland cement increases the resistance of the 
resulting mortar or concrete to the disintegrating effect of sea water. 

Regarding the use of any material added to the concrete mix- 
ture in small quantities in order to reduce permeability, no results 
of practical working tests have demonstrated that the effect of any 
material in reducing permeability is other than mechanical, i.e., 
to supply a deficiency in fine material in a poorly graded concrete 

Allowing the concrete to harden under favorable conditions before 
exposure to the action of sea water greatly increases its resistance to 
attack by the sea water and is recommended wherever possible. 

When concrete is deposited under sea water, such precaution 
should be observed as will prevent the washing of the cement from the 

Forms should be so tight as to prevent the entrance of sea water 
after depositing the concrete, in order that a smooth dense surface 
may be obtained. 

The combined effect of freezing and of sea water is noted on 
marine structures in northern latitudes between high and low tide 
levels. Under these conditions the disintegrating effects are par- 
ticularly severe. 

Dense, properly hardened concrete is not affected by the action 
of sea water. Where the concrete is porous, however, it is likely 
to be damaged by frost action, especially between tides. There is no 
evidence, however, that porous concrete is damaged by sea water 
in latitudes where there is no frost. 

The making of a dense, impermeable concrete by the use of a 
well-graded aggregate, rich mixture, proper consistency, and good 
workmanship, and allowing the concrete to harden under favorable 
conditions before being exposed to the action of sea water, is generally 


conceded to be an efficient means of satisfactorily insuring the pres- 
ervation of concrete in maritime works. 

Concrete Subjected to the Action of Water Containing Alkalies. 
Investigations concerning the effect of ground waters which contain 
alkalies on concrete have disclosed several instances of apparent 
disintegration. The following points have been demonstrated in 
regard to the resistance of concrete to these agencies : 

Concrete in which poor aggregates and lean mixtures have been 
used and in which the material has been carelessly placed, when 
coming in contact with alkali seepage may be affected thereby. 

The aggregates should be composed of materials inert to alkalies 
present in the water. A chemical examination of the sand from coun- 
try known to contain alkaline soils is recommended. 

Water containing substances known to react with the elements 
of the cement should be kept from coming in contact with concrete 
until the latter has thoroughly hardened. 

Care should be taken to provide a smooth surface and sufficient 
slope to the extrados of the arch of tunnel linings when the ground- 
water level lies below the tunnel grade to facilitate the flow of seep- 
age water to the sides. The back filling over the arch should consist 
of porous material such as coarse, crushed stone, for the same reason. 
Side-drains should be used where necessary and connected with an 
underdrain, which should be provided in all cases. 

The measures to be used in making concrete which is to be exposed 
to the action of these deteriorating agencies in order to prevent 
disintegration are the same as recommended for sea water construc- 
tion. Impermeability is the prime requisite, and the results of experi- 
ments and practical tests indicate that concrete, carefully prepared, 
is just as resistant, if not more so, than if mixed with foreign materials 
or special preparations. 

The following instructive conclusions on the effect of sea water 
on concrete are from a paper by Mr. W. Walters Pagon, read before 
the Engineers Club of Baltimore.* Though somewhat a repetition 
of the previous paper, its greater detail warrants its addition 

In order to construct concrete that will have the greatest resistive 
power against the action of sea water (and also probably of alkali 
waters) it must possess the following characteristics: 

The addition of puzzolan in some form is widely practiced in 
Europe and appears to be theoretically correct. It has not been 
tried in America, to the author's knowledge, but is worth an exhaus- 
* " Concrete," Vol. 9, No. 4, October, 1916. 


tive test. The amount should not be over one part nor less than 
one-half part for each part of cement. 

Waterproofing with substances that combine chemically with the 
free lime ought to be successful and is worth testing. 

Between extreme high and low tides the concrete surface should 
be faced continuously, without joints, with about 3 inches of 1 : 1J 
or 1 : 2 mortar made with sand as specified below, well cured before 
coming in contact with the sea water. Facing must be placed simul- 
taneously with the backing. 

The cement should be low in lime and alumina and contain as 
little gypsum as possible. 

Sand must be silicious, uniformly graded from fine to coarse, 
with not less than 50 per cent nor more than 70 per cent passing 
through a No. 20 sieve, and no more than 3 per cent passing a No. 
100 sieve and must have no organic matter coating the grains. It 
must be free from roots and easily disintegrated grains, such as 
feldspar, shells, limestone, mica, etc. It should be washed free 
from clay, and should show a tensile strength for 1 : 3 specimens 
not less than the following percentages of the strength of standard 
Ottawa sand of the same consistency, using the brand of cement 
that is to be used on the work: 

A Percentage 

A e - Strength. 

1 day 85 

7 days 95 

28 days 100 

Where concrete must be exposed to sea water without mortar 
facing, gravel should not be used. Broken stone should be hard, 
durable trap, granite or other dense, hard, insoluble stone. It 
should not exceed f inch in size and should be free from crusher 
dust, sand, dirt, organic matter or other foreign substances. The 
mixture should be 1 : 1J : 3 or 1 : 2 : 4 or should be proportioned 
for maximum density. 

Pure fresh water should be used in sufficient quantity to permit 
the materials to be well puddled and spaded, so that no later surface 
treatment or patching will be require^, but not sufficient to materially 
retard the setting of the cement. Care must be exercised, however, 
to prevent the formation of laitance or pockets of neat cement or 
very rich mortar. 

Forms should be tight to prevent leakage of cement, or, where 
concrete must be submerged immediately, to prevent contact with 
the sea water. 


Facing should be reinforced with steel well covered with mortar 
and securely anchored to the backing. 

No surface treatment should be given. 

The work should be allowed to harden for two weeks, if possible, 
before coming in contact with sea water. Two months is better. 

Sea water work should never be done in cold weather, with tem- 
perature below 40 deg. Fahr. (4.4 deg. Cent.). 

Where possible, pre-cast, mortar-faced blocks cured in damp sand 
for at least one month should be used. The mortar facing should 
not only be on the outside of the block, but should extend on the faces 
which form the bed joints and vertical joints. In this way the facing 
will be continuous, back to such a point, that no water can get into 
the rear of the block. The joints between the blocks should be 
pointed with 1 : 1 mortar of coarse sand to eliminate saturation. 

The most durable surface will be obtained if granite or other dense 
stone be used as facing. This should not be less than 6 inches thick, 
anchored back with wrought-iron clamps and pointed with 1 : 1 
mortar of coarse sand and cement as noted above. 

On mortar or concrete surfaces the growth of barnacles, moss, 
etc., will frequently afford protection. 


THE following report of Committee D-8 of the American Society 
for Testing Materials corroborates the author's information and 
experience in general waterproofing preceding and since its publica- 

The committee reports that while it has not been able to arrive 
at sufficiently definite conclusions to enable it to formulate specifica- 
tions for the making of concrete structures waterproof or for materials 
to be used in such work, it has reached certain general conclusions 
which may be of assistance to the constructor in securing the desired 
result of impermeable concrete. 

Early in the investigation, the work was found to sub-divide 
naturally into three branches, and the conclusions reached will be 
grouped in order under these sub-divisions, which are: 

1. The determination of causes of the permeability of concrete as 
usually made from mixtures of Portland cement, sand and stone, or 
other coarse aggregate, in proportions of from 1 cement, 2 sand and 
4 stone, to 1 cement, 3 sand and 6 stone, and the best methods of 
avoiding these causes. 

2. The rendering of concrete more waterproof by adding to ordi- 
nary mixtures of cement, sand and stone, other substances, which, 
either by their void-filling or repellent action, would tend to make 
the concrete less permeable. 

3. The treatment of exposed surfaces after the concrete or mortar 
has be3n put in place and hardened more or less, either by penetra- 
tive, void-filling or repellent liquids, making the concrete itself less 
permeable or by extraneous protective coatings, preventing water 
having access to the concrete. 

Considering these several sub-divisions separately and in the order 
named, the committee finds : 

1. Causes of Permeability of Concrete. In the laboratory and 
under test conditions using properly graded and sized coarse and fine 
aggregates, in mixtures ranging from 1 cement, 2 sand and 4 stone, 
to 1 cement, 3 sand and 6 stone, impermeable concrete can invariably 

* Proceedings, American Society for Testing Materials, Vol. 13, 1913, p. 459. 



be produced. That even with sand of poor granulometric composi- 
tion, with mixtures as rich as 1 cement, 2 sand and 4 stone, per- 
meable concrete is seldom, if ever, found and is a rare occurrence with 
mixtures of 1 cement, 3 sand and 6 stone. But the fact remains, 
nevertheless, that the reverse obtains in actual construction, per- 
meable concretes being encountered even with 1 cement, 2 sand and 
4 stone mixtures and are of frequent occurrence where the quantity 
of the aggregate is increased. This we attribute to: 

(a) Defective workmanship, resulting from improper propor- 
tioning, lack of thorough mixing, separation of the coarse aggregate 
from the fine aggregate and cement in transporting and placing the 
mixed concrete, lack of density through insufficient tamping or 
spading, and improper bonding of work joints, etc. 

(6) The use of imperfectly sized and graded aggregates: 

(c) The use of excessive water, causing shrinkage cracks and for- 
mation of laitance seams. 

(d) The lack of proper provision to take care of expansion and 
contraction, causing subsequent cracking. 

Theoretically, none of these conditions should prevail on properly 
designed and supervised work, and are avoided in the laboratory 
and in the field, under -test conditions, where speed of construction 
and cost are negligible items, instead of being governing features 
as they must be in actual construction. Properly graded sands and 
coarse aggregares are rarely, if ever, found in nature in sufficient 
quantities to be available for large construction, and the effect of 
poorly graded aggregates in producing permeable concrete is aggre- 
vated by poor and inefficient field work. Even if we could afford 
the added expense of screening and remixing the aggregates so as to 
secure proper granulometric composition to give the density required 
and to make untreated concretes impermeable, it is seemingly a 
commercial impossibility on large construction to obtain workman- 
ship even approximating that found in laboratory work. It there- 
fore seems that we can secure impermeable concrete most economic- 
ally by adopting some special waterproofing treatment. 

2. Addition of Foreign Substances to Cement or During Mixture. 
The committee finds that in consequence of the conditions outlined 
above, the use of substances calculated to make the concrete more 
impermeable, either incorporated in the cement or added to the con- 
crete during mixing, has become general. This has resulted in the 
development and placing on the market of numerous patented or 
proprietary waterproofing compounds, the composition of which is 
more or less of a trade secret. 


While it has been impossible for the committee to test all of the 
special waterproofing compounds being placed on the market, it has 
investigated a sufficient number of these, as well as the use of certain 
very finely divided, naturally occurring or readily obtainable com- 
mercial mineral products, such as finely ground sand, colloidal clays, 
hydrated lime, etc., to form a general idea of the value of the different 
types. The committee finds: 

(a) That the majority of patented and proprietary integral com- 
pounds tested have little or no permanent effect on the permeability 
of concrete and that some of these even have an injurious effect on 
the strength of mortar and concrete in which they are incorporated ; 

(6) That the permanent effect of such integral waterproofing 
additions, if dependent on the action of organic compounds, is very 

(c) That in view of their possible effect, not only upon the early 
strength, but also upon the durability of concrete after considerable 
periods, no integral waterproofing material should be used unless 
it has been subjected to long-time practical tests under proper observa- 
tion to demonstrate its value, and unless its ingredients and the pro- 
portion in which they are present are known; 

(d) That in general, more desirable results are obtainable from 
inert compounds acting mechanically than from active chemical 
compounds whose efficiency depends on change of form through 
chemical action .after addition to the concrete; 

(e) That void-filling substances are more to be relied upon than 
those whose value depends on repellent action; 

(/) That, assuming average quality in sizing of the aggregates 
and reasonably good workmanship in the mixing and placing of the 
concretes, the addition of from 10 to 20 per cent of very finely divided 
void-filling mineral substances may be expected to result in the pro- 
duction of concrete which under ordinary conditions of exposure 
will be found impermeable, provided the work joints are properly 
bonded, and cracks do not develop on drying or through change in 
volume due to atmospheric changes, or by settlement. 

3. External Treatments. While external treatment of concrete 
would not be necessary if the concrete itself, either naturally or by 
the addition of waterproofing material, was impermeable to water, 
it has been found in practice that in large construction, no matter 
how carefully the concrete itself has been made, cracks are apt to 
develop, due to shrinkage in drying out, expansion and contraction 
under change of temperature, moisture content and through settle- 


It is, therefore, often advisable on important construction to 
anticipate and provide for the possible occurrence of such cracks by 
external treatment with protective coatings. Such coating must be 
sufficiently elastic and cohesive to prevent the cracks extending 
through the coating itself. The application of merely penetrative 
void-filling liquid washes will not prevent the passage of water due 
to cracking of the concrete. The committee has, therefore, divided 
surface treatments into two heads: 

(a) Penetrative void-filling liquid washes. 

(6) Protective coatings, including all surface applications intended 
to prevent water coming in contact with the concrete. 

While many penetrative washes are efficient in rendering concrete 
waterproof for limited periods, their efficiency is apt to decrease with 
time and it may be necessary to repeat such treatment. Some of 
these washes may be objectionable, due to discoloring the surface to 
which they are applied. The committee, therefore, believes that the 
first effort should be made to secure a concrete that is impermeable 
in itself and that penetrative void-filling washes should only be re- 
sorted to as a corrective measure. 

While protective extraneous bituminous or asphalt coatings are 
unnecessary, so far as the major portion of the concrete surface is 
concerned, provided the concrete either in itself or through the addi- 
tion of internal compounds is made impermeable, they are valuable 
as a protection where cracks develop in a structure. It is therefore 
recommended that combination of the two methods integral and 
extraneous waterproofing be adopted in especially difficult or im- 
portant work. 

Considering the use of bituminous or asphaltic coatings, the com- 
mittee finds: 

(a) That such protective coatings are often subject to more or 
less deterioration with time, and may be attacked by injurious vapors 
or deleterious substances in solution in the water coming in contact 
with them. 

(6) That the most effective method for applying such protec- 
tion is either the setting of a course of impervious brick, dipped in 
bituminous material, into a solid bed of bituminous material, or the 
application of a sufficient number of layers of satisfactory membra- 
nous material cemented together with hot bitumen. 

(c) That their durability and efficiency are very largely dependent 
on the care with which they are applied. 

Such care refers particularly to proper cleaning and preparation 
of the concrete to insure as dry a surface as possible before applica- 


tion of the protective covering, the lapping of all joints of the mem- 
branous layers, and their thorough coating with the protective mate- 
rial. The use of this method of protection is further desirable because 
proper bituminous coverings offer resistance to stray electrical cur- 

So far, the committee has considered only concretes of the usual 
proportions, namely, those ranging from 1 cement, 2 sand and 4 stone, 
to 1 cement, 3 sand, and 6 stone. It has been suggested that im- 
permeable concretes could be assured by using mixtures considerably 
richer in cement. While such practice would probably result in an 
immediate impermeable concrete, it is believed by many that the 
advantage is only temporary, as richer concretes are more subject 
to check cracking and are less constant in volume under changes of 
conditions of temperature, moisture, etc. Therefore, the use of more 
cement in mass concrete would cause increased cracking, unless 
some means of controlling the expansion and contraction be dis- 
covered. With reinforced concrete the objection is not so great, as 
the tendency to cracking is more or less counteracted by the re- 

It has also been suggested that the presence in the cement of a 
larger percentage of very fine flour might result in the production of 
a denser and more impermeable concrete, through the formation of a 
larger amount of colloidal gels. 

Neither of these suggestions have been especially investigated 
by the committee. Both appeal to the committee, however, for the 
reason that they substitute active cementitipus substances for the 
largely inactive void-filling materials previously recommended, thus 
increasing the strength of the concrete. 

In conclusion, thp committee would point out that no addition 
of waterproofing compounds or substances can be relied upon to 
completely counteract the effect of bad workmanship, and that the 
production of impermeable concrete can only be hoped for where 
there is determined insistance on good workmanship. 


Acid Sludge. A waste mixture of sulphonated hydrocarbons resulting from 
the treatment of bitumens with sulphuric acid. 

Aggregate. The inert material, such as sand, gravel, shell, slag or broken 
stone, or combinations thereof, with which the cementing material is mixed to 
form a mortar or concrete. 

Albertite. A soft jet black mineral (asphaltic hydrocarbon) derived from 
petroleum by natural oxidation, obtained in Canada. 

Alum. A white crystalline substance consisting of a hydrated double sul- 
phate of aluminum and potassium. See Chapter V. 

Anthracene. A waxy crystalline hydrocarbon found principally in coal tars. 

Artificial Bitumens. Hydrocarbon residues produced by the partial or frac- 
tional distillation of bitumen. 

Artificial Gilsonite. A product obtained from the distillation of a mixture of 
fish remains and wood and redistillation of the resulting oil. 

Asbestine. A trade name for a certain grade of powdered asbestos used in 
paints as a filler. 

Asbestos. A mineral of fibrous crystalline structure composed, chemically, 
of silicates of lime and magnesia, and alumina. See Chapter V. 

Asbestos Felt. Sheets made of asbestos shreds. See Chapter V. 

Ash Water Glass. Same as water glass. 

Asphalt. Solid or semi-solid native bitumens, solid or semi-solid bitumens 
obtained by refining petroleums, or solid or semi solid bitumens which are combi- 
nations of the bitumens mentioned with petroleums or derivatives thereof, which 
melt on the application of heat, and which consist of a mixture of hydrocarbons 
and their derivatives of complex structure, largely cyclic and bridge compounds. 

Asphalt Cement. A fluxed or unfluxed asphaltic material, especially prepared 
as to quality and consistency. 

Asphalt Mastic. A term frequently applied to refined asphalt, particularly 
to that obtained from bituminous rocks. A mixture of fine mineral matter and 

Asphalt Pavement. A pavement composed of a mixture of asphalt and sand 
or powdered mineral dust or both. 

Asphalt Putty. A mixture of a liquid and a -solid asphalt (and fine mineral 
matter, usually) or asphalt and coal-tar pitch, having a particular consistency. 

Asphaltenes.* The components of the bitumen in petroleum, petroleum 
products, malthas, asphalt cements, and solid native bitumens, which are soluble 
in carbon disulphide, but insoluble in paraffin naphthas. 

Asphaltic. Similar to, or essentially composed of, asphalt. 

* Adopted by the American Reporters on Communication No. 10 at the third International 
Road Congress. 


Asphaltic Coal. Solid forms of asphalt (originally derived from petroleum) 
which, through loss of their oil content, by oxidation, resemble glance coal. 

Asphaltic Concrete. Broken stone bound together with asphaltic cement. 

Asphaltic Limestone. Limestone or limestone sands naturally impregnated 
with asphalt or maltha, and known as " asphalt " in Europe. 

Asphaltic Oils. Asphaltic petroleums. 

Asphaltic Petroleums. Petroleums containing an asphaltic base. 

Asphaltic Sandstone. Sandstone naturally impregnated with asphalt or 
maltha and known as " asphalt " in Europe. 

Asphaltite. Same as asphaltic coal. 

Asphaltum. The Latin form of the English word asphalt. 

Bakelite. A hard amber-like substance manufactured from the coal-tar 
derivatives phenol and formaldehyde. See Chapter V. 

Bank-run Gravel. The normal product of a gravel bank. 

Barret Specification Felt. Trade name for a proprietary tar-treated roofing 

Baume Gravity. An arbitrary scale of specific gravity or density of liquids, 
usually expressed as deg. Baume, or B. on a hydrometer. See Chapter XII. 

Benzene. Benzol (C 6 H 6 ). See Chapter V. 

Benzine. A light and volatile fraction of petroleum. See Chapter V. 

Benzol. A light, volatile, colorless coal-tar distillate of the formula C fi H R . 
See Chapter V. 

Bermudez Asphalt. A very pure semi-solid native asphalt from Bermudez. 

Binder. The bituminous cementing material employed in the membrane 
system of waterproofing. 

Bitumen. A natural hydrocarbon mixture of mineral occurrence, widely 
diffused in various forms which grade by imperceptible degrees from a light gas to 
a solid; commercially the term includes only the heavy liquid and solid asphalts. 
Frequently coal-tar pitch is so referred to. 

Bituminous. A term applied to materials containing bitumen. 

Bituminous Cement. A bituminous material suitable for use as a binder 
having cementing qualities which are dependent mainly on its bituminous char- 

Bituminous Emulsion. A mixture of a bituminous oil and water made 
miscible through the action of a saponifying agent or alkaline soap. 

Bituminous Paints. Mixtures of liquid paraffin and asphalt or coal-tar; 
mixtures of bitumen with some drying oil. See Chapter V. 

Bituminous Putty. A mixture of bituminous materials and whiting or other 
mineral, of a putty-like consistency. 

Bituminous Rock. Same as rock asphalt. 

Blown Asphalt. Asphalt through which air has been blown during the 
process of refining. 

Blown Oils. Blown petroleum. 

Blown Petroleum.* Semi-solid or solid products produced primarily by the 
action of air upon originally fluid native bitumens which are heated during the 
blowing process. 

Building Paper. A paper, usually a heavy grade and strong, sized with rosin 
to make it water resisting and used to sheath buildings to exclude drafts. 

*Adopted by the American Reporters on Communication No. 10 at the third International 
Road Congress. 


Built-up Roofs. Roofing consisting of several plies of treated felt cemented 
with asphalt or coal-tar pitch. See Chapter III. 

Burlap. A woven fabric made of jute. See Chapter V. 

Byerlite. Common and trade-name of a blown asphaltic petroleum dis- 
tinguished from ordinary blown petroleums principally by the use of oxygen in- 
stead of air in the blowing process. 

Caffall Process. A proprietary process for applying paraffin to exterior 
masonry surfaces. 

Calcium Compounds. Salts of metal calcium or lime. See Chapter V. 

Caoutchouc. A hydrocarbon with the approximate formula of CioHi 6 and 
possessing properties similar to India rubber. 

Carbenes.* The components of the bitumen in petroleums, petroleum 
products, malthas, asphalt cements, and solid native bitumens, which are soluble 
in carbon disulphide, but insoluble in carbon tetrachloride. 

Carbon Bisulphide. The volatile and extremely inflammable compound of 
carbon and sulphur (CS 2 ) . 

Carbon Disulphide. Same as carbon bisulphide. 

Carbon Tetrachloride. A volatile noninflammable compound of carbon and 
chlorine (C-Cl t ). 

Carborundum. An artificial abrasive material resulting from the burning, 
in an electric furnace, of a mixture of sand, coke, sawdust and salt. 

Casein. An albumin found in milk. See Chapter V. 

Cement. An adhesive substance used for uniting particles of materials to 
each other. Ordinarily applied, only to calcined " cement rock," or to arti- 
ficially prepared, calcined, and ground mixtures of limestone and silicious mate- 
rials. Sometimes used to designate bituminous binder used in waterproofing. 

Cement Floor. A name commonly applied to concrete floors with or without 
a mortar top. 

Cerasin. Ozocerite. 

Cerite. Ozocerite. 

China Clay. Kaolin. 

Chinawood Oil. Oil pressed from the seeds of the wood-oil tree of China 
and Japan. See Chapter V. 

Choctaw. Name of mining locality (in Oklahoma) of grahamite; some- 
times, but incorrectly used for grahamite. 

Clay. Finely divided earth, generally silicious and aluminous, which will 
pass a 200-mesh sieve. 

Coal Tar. The mixture of hydrocarbon distillates, mostly unsaturated ring 
compounds, produced in the destructive distillation of coal. See Chapter V. 

Coal-tar Pitch. The residue (of a viscous consistency) resulting from the 
distillation of coal-tar. See Chapter V. 

Coat. (1) The total result of one or more surface applications. (2) To 
apply a coat. 

Coke-oven Tar. Coal tar produced in by-product coke ovens in the manu- 
facture of coke from bituminous coal. See Chapter V. 

Colloidal Material. A gelatinous substance, resembling glue or jelly, and 
consisting of microscopically fine particles of matter. 

Colophony. Rosin. 

* Adopted by the American Reporters on Communication No. 10 at the third International 
Road Congress. 


Compressed Asphalt. A European (particularly French) term for rock asphalt 

Concrete Floor Hardener. A powdered metal or mineral usually troweled on, 
or a liquid chemical reagent usually brushed on, the surface of a concrete floor 
to harden same. 

Concrete Primer. A thin liquid compound applied as a first coat to a con- 
crete surface preparatory to being coated with a more viscous compound. 

Consistency.* The degree of solidity or fluidity of bituminous materials. 

Corundum. A crystalline mineral abrasive mined in the United States and 
ground for use. 

Cotton Drill. A woven cotton fabric. See Chapter V. 

Cracked Oil. Petroleum residuum which have been overheated in the proc- 
ess of manufacture. 

Cracking. The process of breaking down hydrocarbon molecules by the 
application of heat. 

Crude Asphalt. Unrefined asphalt. 

Crude Oil. Unrefined oil. 

Crude Tar. Unrefined coal tar. 

Cut-back Products. Petroleum, or tar-residuums, which have been fluxed 
each with its own or similar distillate, to a desired consistency. 

Dampproofing. The process of treating masonry internally or externally, 
to prevent dampness or moisture from penetrating the masonry. 

Dead Oils. Heavy oils with a density greater than water distilled from tars. 

Dehydrated Tars. Crude tar from which all water has been removed. 

Destructive Distillation. The distillation of organic compounds at suf- 
ficiently high temperatures so that their identity is destroyed. 

Dipping Compound. Bituminous compound used for coating pipes and iron 
tunnel segments to preserve them against rust. 

Drainage. Provision for the disposition of water in or about a structure. 

Dust. Earth or other matter in fine, dry particles, so attenuated that they 
can be raised and carried by air currents. The product of the crusher passing 
through a fine sieve. 

Eastern Petroleum. Petroleum found in the eastern part of the United States, 
principally Pennsylvania. 

Elaterite. A soft elastic variety of asphalt, resembling rubber, Also an 
appropriated name of a proprietary waterproofing compound. See Chapter V. 

Emulsion. A combination of water and oily material made miscible through 
the action of a saponying agent. 

Expansion Joint. A separation of the mass of a structure, usually in the 
form of a joint filled with elastic material, which provides the means for slight 
movement in the structure. 

Fabric. A cotton cloth or burlap treated with asphalt or coal-tar pitch. 

Felt. A soft form of paper sheet composed chiefly of pulp and rags and 
saturated with coal-tar pitch or asphalt. See Chapter V. 

Filler. (1) Relatively fine material used to fill the voids in concrete aggre 
gate. (2) Material used to fill the voids in expansion joints. 

Fixed Carbon.* The organic matter of the residual coke obtained upon 
burning hydrocarbon products in a covered vessel in the absence of free oxygen. 

Flashing. A piece of metal or other waterproof material used to keep water 

* Adopted by the Am, Soc. for Testing Materials. 


from penetrating the joints between a wall or projection, and the roof or other 
flat part of the structure. See Chapter III. 

'Floating. Smoothing, with a trowel, the surface of mortar or concrete. 

Flux.* Bitumens, generally liquid, used in combination with harder bitu- 
mens for the purpose of softening the latter. 

Free Carbon. In tars, organic matter which is insoluble in carbon bisul- 
phide. See Chapter VII. 

Fuller's Earth. A fine-grained earthy material of cretaceous formation and 
resembling clay in appearance. 

Furring Compound. A compound used to bond plaster to masonry. 

Gaging Water. Water (in measured quantities) used in mixing mortar or 
concrete to a required consistency. 

Gas Black. Soot from natural gas. 

Gas-drip. A condensate from illuminating gas, present to a greater or less 
degree in all gas mains and tanks and an effective solvent of most bituminous 

Gas-house Coal Tar. Coal-tar produced in gas-house retorts in the manu- 
facture of illuminating gas from bituminous coal. 

Gasoline. A very volatile distillate of petroleum. See Chapter V. 

German Wax. A manufactured wax or blend of beeswax and other waxes. 

Gilsonite. Glance pitch; a pure hard lustrous asphalt found principally in 
Utah, U. S. A. See Chapter V. 

Glance Pitch. A very pure solid asphalt or gum asphalt. 

Grahamite. A pure, solid lusterless asphalt. See Chapter V. 

Graphite. A soft dark-colored form of carbon with considerable luster. See 
Chapter V. 

Gravel. Small stones or pebbles, usually found in natural deposits more or 
less intermixed with sand, clay, etc., but in which mixture the particles which 
will not pass a 10-mesh sieve predominate. 

Grit. Stone chips, slag chips, small pebbles or rounded rock particles graded 
or ranging in size between | and f inch. 

Ground Water. That part of rain, hail, or snow, that has percolated through 
and accumulated in the ground as water chiefly in consequence of an underlying 
impervious strata. 

Ground- water Level. The upper surface of ground water. See Chapter I. 

Grout. A mixture of cement and water or cement sand and water of thinner 
consistency than mortar. See Chapter V. 

Grouting. The process of injecting grout or mortar to fill small holes and 
seams in and around subsurface structures. See Chapter II. 

Gum. Varnish gum; loosely applied to asphalt. 

Gum Resins. Resins exuding from cuts in pines. 

Gumlac. Shellac. 

Gunite. Trade name for the mortar made and "shot" from the cement 
gun. See Chapter II. 

Gutta-percha. A substance consisting of a dried milky juice in many respects 
similar to caoutchouc, but not elastic; extracted from certain trees in the iropics. 

Gypsum. Erroneously referred to as plaster of Paris but actually a hydrated 
calcium sulphate (CaSO 4 , 2H 2 0). 

* Adopted by the American Reporters on Communication No. 10 at the third International 
Hoad Congress. 


High Carbon Tars. Tars containing a high percentage of free carbon (between 
15 and 25 per cent). 

Hot Stuff. Washing soda (carbonate of lime) when used to quicken the set- 
ting time of mortar. Colloquially, also hot molten asphalt, or coal-tar pitch, or 
mastic made from these. 

Hydrated Lime. A finely divided white powder, made of ordinary lime to 
which has been added just sufficient water to insure complete slaking, and 
leaving the product dry. See Chapter V. 

Hydrocarbons. Chemical compounds composed of the elements hydrogen 
and carbon. 

Hydrolithic. Proprietary trade name applied to the integral system of 

Hydrolytic. Name commonly applied to materials used in integral water- 
proofing which tend to prevent the percolation of water through the treated 

Hydrex Compound. Trade name for a proprietary asphalt. 

Imitatite, A black, hard variety of bitumen. 

Impsomite. A solid bitumen resembling gilsonite, found in Oklahoma, U.S.A. 

Integral Compound. A material incorporated in mortar or concrete, previous 
to or during mixing, to waterproof same. See Chapter II. 

Integral System. The process .of incorporating waterproofing materials in 
mass mortar or concrete. See Chapter II. 

Iron (Powdered). Cast iron or pig iron in powder form. 

Isinglass. The dried swimming bladders of several varieties of fish from 
which gelatine is extracted. 

Joint Filler. Any compound used for filling joints between moving parts 
of steel or masonry (structures) subject to expansion, contraction and vibration. 
See Chapter IV. 

Kaolin. A fine clay the purity of which gives it a white color. 

Lake Pitch. A plastic porous, and about 50 per cent impure asphalt from 
the asphalt " lake " in the island of Trinidad. 

Land Pitch. A surface deposit of solid Trinidad Lake asphalt which is 
tougher and more tenacious than the " lake " asphalt. 

Land Plaster. Powdered gypsum; also, but incorrectly, used to designate 
plaster of Paris. 

Lap Cement. A liquid bituminous compound used for cementing the laps 
of ready roofing. 

Larutan Compound. Trade name of a proprietary asphalt. 

Larutan System. Application of a waterproofing membrane in the form of 
small squares of asphalt-treated cotton fabric. See Chapter II. 

Layer. A course or coat made in one application. 

Lime. A white substance resulting from the burning of limestone. See 
Chapter V. 

Linseed Oil. Oil obtained from the seed of flax by pressing. See Chapter V. 

Lithocarbon. A commercial name for an asphaltic limestone found in 
Uvalde, Texas, U. S. A. 

Low Carbon Tars. Tars containing a low percentage of free carbon (between 
5 and 15 per cent). 

Maltha. A natural or artificial asphalt containing sufficient lighter compounds 
to be liquid. 


Malthene. Those portions of asphalt and similar materials soluble in both 
carbon bisulphide and petrolic ether and not readily volatile at a temperature of 
163 deg. Cent. 

Manjak. A pure, black, lustrous bitumen from Barbadoes, probably related 
to grahamite. 

Mastic. A mixture of fine mineral matter and asphalt or coal-tar pitch, 
applicable in a heated condition. See Chapter V. 

Mastic Rock. Rock asphalt. 

Membrane. In waterproofing, a thin layer or layers of bituminous material 
with or without fabric reinforcement, placed on or about a structure. 

Membrane System. The system of applying an elastic, membranous water- 
proofing material. See Chapter II. 

Metal Primer. A first coat of paint or preserving compound applied to iron 
or steel. 

Mineral Naphtha. A volatile petroleum distillate heavier than gasoline. 

Mineral Oil. Petroleum. 

Mineral Pitch. A popular name for asphalt. 

Mineral Rubber. A bitumen of rubbery consistency. 

Mineral Tar. A liquid bitumen, of a viscid, tarry nature. 

Mineral Wax. A common term for ozocerite. 

Minwax. A proprietary asphalt. 

Mortar. A mixture of sand, cement, or lime (or both) and water mixed to 
a paste consistency. 

Naphtha. A volatile petroleum hydrocarbon distillate heavier than 

Naphthalene. A white solid crystalline hydrocarbon, occurring principally 
in coal tar, of the chemical formula Ci H 8 . 

Native Bitumens. Bitumens occurring in nature, and for waterproofing 
purposes, generally as liquids, viscous liquids or solids. 

Native Paraffin. Ozocerite. 

Natural Cement. A fine cementing powder made by burning and grinding a 
cement rock at a somewhat lower heat than Portland cement. See Chapter V. 

Neponsit Felt. Trade name for a proprietary roofing felt. 

Neutral Oil. Neutral mineral oil. 

Oil Asphalts. Artificial oil pitches or asphaltic cements produced as a resid- 
uum from asphaltic petroleum. 

Oil Pitches. More or less hard oil asphalts. 

Oil-gas Tars. Complex hydrocarbon liquids produced by cracking oil vapors 
at high temperatures in the manufacture of oil gas or carburetted water gas. 

Oil-tar Pitch. A viscous residuum of any desired consistency from the 
distillation of oil tars. See Chapter V. 

Ozocerite. A yellow or brown hydrocarbon, greasy, waxlike substance, 
occurring in the form of small veins in tertiary rock in Galacia, Austria and 
Utah, U. S. A. 

Ozokerite. Same as Ozocerite. 

Paraffin. Commonly, the same as paraffine; a hard, white, wax-like sub- 
stance, chemically of the higher hydrocarbons. See Chapter V. 

Paraffine. A term covering a number of greasy crystalline hydrocarbons of 
the paraffin series. 

Paraffin Naphtha. Naphtha from paraffin petroleum. 


Paraffin Oil. A heavy liquid fraction of the manufacture of paraffin from 
petroleum. See Chapter V. 

Paraffin Petroleum. Petroleum, the base of which is principally of the paraffin 
series of hydrocarbons. 

Paraffin Scale. Solid paraffins in asphalt. See Chapter V. 

Petrolene. Those portions of asphalt and similar materials which are 
soluble both in carbon bisulphide and petrolic ether, and which are volatile at 
163 deg. Cent, and below. 

Petroleums. Native mineral oils or fluid native bitumens of variable com- 

Petrolic Ether. A volatile naphtha lighter than gasoline, obtained from 

Pine Oil. A heavy distillate of rosin. 

Pine Tar. Gum of the pine tree from an incision or by distillation of the wood ; 
common rosin. 

Pipe Coating. A bituminous compound applied hot or cold to iron or steel 
pipes for preservation purposes. 

Pitch. A sticky resin from pine tar. Semi-solid or solid residues from the 
distillation of bitumen; usually applied to residue obtained from tar. Short, for 
coal-tar pitch. 

Pitch (Hard). Pitch showing a penetration of not more than ten. 

Pitch (Soft). Pitch showing a penetration of more than ten. 

Pitch (Straight-run).* A pitch run in the initial process of distillation, to 
the consistency desired without Subsequent fluxing. 

Plaster Bond. Name of various bituminous compounds used for bonding 
plaster to masonry walls, and which also serve as dampproofing mediums. 

Plaster of Paris. A hydraulic cement; a chalky powder resulting from the 
calcination of pure gypsum (a hydrated calcium sulphate) at a temperature 
between 250 and 400 deg. Fahr. losing thereby three-quarters of its water of 

Plastic Roofing. A plastic (when warm) roofing compound applied 'with a 
trowel, composed of some fine or fibrous inert substance mixed with tar or other 

Plastic Slate. A mixture of coal tar and powdered slate. 

Portland Cement. A fine cementing powder made by carefully burning and 
grinding a cement rock or an artificial mixture of limestone and clay. See Chap- 
ter V. 

Primer. A first coat applied to masonry preparatory to receiving the suc- 
cessive coats of material for waterproofing or dampproofing purposes. 

Puzzolan Cement. A very fine cementing powder made by mechanically 
mixing and powdering slaked lime and volcanic ash or slag. 

Pyrobitumens. Mineral organic substances forming bitumens upon being 
subjected to destructive distillation. 

Pyrogenetic. That which originates from the action of heat. 

Quasi-colloidal Bodies. Like, or nearly colloidal, particles. 

Quasi-soap. Like, or as if it were, soap. 

Red Rope Paper. A red variety of building paper partly composed of rope 

Reduced Oils. Reduced petroleums. 

* Proposed by the Committee on Standard Test? for Road Materials (Committee D-4) 
of the American Society for Testing Materials. 


Reduced Petroleums. Residual oils from crude petroleum after removal of 
water and some volatile oils, but with the base chemically unaltered. 

Refined Asphalt. Bitumen after it has been freed wholly or in part from 
its impurities. 

Refined Tar. A tar freed from water by evaporation or distillation which 
is continued until the residue is of desired consistency or a product produced by 
fluxing tar residium with tar distillate. 

Residual Oils. Residual petroleums. 

Residual ^Petroleum. Viscous residue from the distillation of crude petroleum 
with all the burning oils removed. 

Residual Tars. Tar pitch or viscous residue from the distillation of crude 
tar with all the light oils removed. 

Resin. A dried and hardened pitch from pine and similar trees. See Chap- 
ter V. 

Rock Asphalt. A solid asphalt obtained from a naturally impregnated 
limestone or sandstone, also the naturally impregnated stone. 

Roofing Cement. A plastic mixture of paint skins, coal tar, pine tar and 
soya oil commonly used to seal flashing joints. 

Roofing Gravel. Approximately f-inch gravel. 

Roofing Slag. Slag crushed to the size ranging between \ and Hnch. 

Rosin. Pine pitch with the chemical formula C 4 4H 62 O4. See Chapter V. 

Salammoniac. Ammonium chloride; a white crystalline soluble substance 
(NH 4 C1). See Chapter V. 

Sand. Finely divided rock detritus the particles of which will pass a 10-mesh 
and be retained on a 200-mesh screen. 

Sand Cement. A very fine cementing powder made by grinding together 
a mechanical mixture of Portland cement and pure, clean sand. 

Semi-asphaltic Oils. Semi-asphaltic petroleum. 

Semi-asphaltic Petroleum. Petroleum of a semi-asphaltic base. 

Sheet Mastic. Bituminous mastic in the form of a sheet used for paving 
and waterproofing purposes. See Chapter II. 

" Short." A term applied to materials possessing little ductility. 

Soap. A metallic salt of fatty acid. See Chapter V. 

Soda Ash. Washing soda (carbonate of lime) of the chemical formula 
(Na 2 C0 3 , 10H a O). 

Soluble Glass. Water glass. 

Stearate. A salt of stearic acid. See Chapter V. 

Stearic Acid. A derivative product of the more solid fats of the animal 
kingdom. (CH 3 (CH 2 ) 16 COOH). See Chapter V. 

Stearin. The chief ingredient of suet and tallow. See Chapter V. 

Stearin Pitch. A black, elastic, non-brittle, animal by-product obtained from 
stearic acid in the manufacture of candles. See Chapter V. 

Subway Asphalt. Common name for a particular quality of asphalt used in 
waterproofing the New York Subways. See Chapter VIII. 

Subway Pitch. Common name for a straight-run coal-tar pitch used in 
waterproofing subways in New York City. See Chapter VIII . 

Suet. The hard and semi-fusible fat about the kidneys and loins of animals. 
See Chapter V. 

Surface Coating. Any compound applied to a masonry surface for damp- 
proofing or waterproofing purposes. 


Sylvester Process. The process of applying alternate coats of soap and alum 
solutions for waterproofing and dampproofing purposes. See Chapter II. 

Tar Pitches. Semi-solid or solid residual tars. 

Tar. Bitumen which yields pitch upon fractional distillation and which is 
produced as a distillate by the destructive distillation of bitumens, pyrobitumens, 
or organic material. See Chapter V. 

Texene. A trade name for a turpentine substitute. 

Torpedo Gravel. A coarse hard grit. 

Trinidad Asphalt. A solid or semi-solid asphalt, brown to black in color, 
porous and about 50 per cent impure, obtained from the island of Trinidad. 

Turrellite. A black, hard variety of bitumen. 

Vintaite. Gilsonite. 

Varnish Gum. Any resinous substance excluding rosin. A term used to 
designate, but incorrectly so, asphalt and coal tar when used in proprietary water- 
proofing compounds. 

Viscosity. The measure of the resistance to flow of a bituminous material, 
usually stated as the time of flow of a given quantity of the material through a 
given orifice. 

Volatile. Applied to those fractions of bituminous materials which will 
evaporate at climatic temperatures. 

Water Absorbent. A property of a floor-hardening or waterproofing material 
which makes it readily miscible with water. 

Water Glass. Sodium silicate (Na.Si,O 9 ) or alkaline silicates soluble in 

Water Repellent. A property of a waterproofing material which hinders 
or prevents its miscibility with water. 

Water Table. Loosely applied to ground -water level. 

Waterproofing. The process of treating masonry to exclude or prevent the 
percolation of moisture or water through it. 

Water-gas Tar. A liquid hydrocarbon produced by cracking oil vapors in 
the manufacture of carburetted water-gas. See Chapter V. 

Wurtzelite. A black, hard variety of bitumen. 


The following reference literature is arranged only approximately according 
to the caption topics. Most of this literature was consulted in the preparation of 
this book, acknowledgments being made in foot-notes. The author is gratified 
to note the increased interest manifested in waterproofing engineering since the 
commencement of this book, four years ago, and the broader viewpoint assumed 
by writers of modern literature on the art of waterproofing. 

Asphalt and Tar. 

Richardson's Modern Asphalt Pavement. 

Bituminous Road and Paving Materials, by Hubbard. 

The Art of Roadmaking, by Harwood Frost. 

Effect of Illuminating Gas on Asphalt Pavements, Eng. News, Mar. 4, 19L K , 
Vol. 73, No. 9, p. 441. 

Waterproofing, by Boorman, Proceedings National Association of Cement 
Users, 1909. 

Coke-oven Tars of the United States. Office of Public Roads, Circular No. 
97, U. S. Dept. Agriculture, 1912. 

Concrete in General. 

Concrete, Plain and Reinforced, by Taylor and Thompson. 

Concrete, Plain and Reinforced, by Homer A. Reid. 

Reinforced Concrete, by Buel and Hill. 

Cairn's " Cement and Concrete." 

Reinforced Concrete, by Marsh. 

Oil-mixed Portland Cement Concrete, Bulletin No. 230, Office of Public 
Roads, U. S. Dept. of Agriculture, 1915. 

Concrete in Sea Water. 

The effect of SO 3 in Portland Cement. Proceedings of Association of German 
Portland Cement Manufacturers, 1911. 

" Action of Sea Water on Hydraulic Binding Media," by Lombard and 
Deforge, International Association for Testing Materials Proceedings, 1912. 

" Action of Sea Water on Reinforced Concrete," by de Blocq van Kuffeler, 
International Association for Testing Materials Proceedings, 1912. 

" The Different Iron and Slag Cements," Engineering News, September 7, 
1911, Vol. 66, No. 10, Editorial. 

" Ferrite Cement and Ferro Portland Cement," by E. C. Eckel, Engineering 
News, Aug. 3, 1911, Vol. 66, No. 5. 

"The State of Preservation of Test Blocks," by W. Czarnowski. Inter- 
national Association for Testing Materials, 1912. 



" Cement in Sea Water," by A. Poulson. International Association for Test- 
ing Materials, 1909. 

" Official German Recognition of the Harmless Nature of a Slag Addition to 
Portland Cement Clinker." Engineering News, September 7, 1911. 

" Experiments on the Decomposition of Mortars by Sulphate Waters," by 
G. A. Bied. International Association for Testing Materials, 1909. 

" Some Observations on the Disintegration of Cinder Concrete," by George 
Borrowman. Journal of Industrial and Engineering Chemistry, June, 1912. 

" Disintegration of Fresh Cement Floor Surfaces," by Alfred H. White, 
American Society for Testing Materials, Vol. 9. 

Relative Effects of Frost and Sulphate of Soda Effloresence Tests on Build- 
ing Stones. Transactions of the American Society of Civil Engineers, Vol. 33, 

Action of the Salts in Alkali Water and Sea Water on Cements. U S. Bureau 
of Standards, Bulletin No. 12, Nov., 1912. 

Action of Sea-water on Mortar. Cement Age, March, 1907. 

Destruction of Cement Mortar and Concrete by Alkali at Great Falls, Mont. 
Eng. Cont., June 24, 1908. 

Durability of Stucco and Plaster Construction. U. S. Bureau of Standards 
Bulletin No. 70, Jan., 1917. 

What is the Trouble with Concrete in Sea Water? Engineering News-Record, 
Vol. 79, No. 12, page 532. 


The prevention of Dampness in Houses, by A. F. Keim. 


Electrolysis in Concrete; Tech. Paper No. 18, Bureau of Standards, U. S. 
Dept, of Commerce, 1913. 

Surface Insulation of Pipes as a Means of Preventing Electrolysis. Tech. 
Paper No. 15, Bureau of Standards, U. S. Dept. of Commerce, 1914. 

Special Studies in Electrolysis Mitigation, Tech. Paper No. 32, Bureau of 
Standards, U. S. Dept. of Commerce 19 

Engineering Structures. 

Waterproofing An Engineering Problem, by Myron H. Lewis. Proc. 
Engrs. Club of Phila.,. Vol. 25, page 339, Oct., 1908. 

Waterproofing, Progress Report of Special Committee on Concrete and Rein- 
forced Concrete. Trans. Am. Soc. C. E., Vol. 66, page 444, March, 1910. 

Waterproofing Cement Mortars and Concretes, by H. Wiederhold. Proc. 
Natl. Assoc. Cement Users, Vol. 3, page 228, 1907. 

Waterproofing Cement Mortars and Concretes, by Edward W. De Knight. 
Proc. Natl. Assoc. Cement Users, Vol. 3, page 238, 1907. 

Waterproofing Concrete and Masonry, by Edward W. De Knight, Eng. News, 
Vol. 57, page 187, Feb. 14, 1907. 

Waterproofing Cement Structures, by James L. Davis, Proc. Natl. Assoc. 
Cement Users, Vol. 4, page 323, 1908. 

Waterproofing of Concrete Structures, pages 344-74. Hand-book for Cement 
and Concrete Users, by Lewis and Chandler. 

Making Concrete Waterproof, by Prof. I. O. Baker, Eng. News, Vol. 62, page 
390, Oct. 7, 1909. 


Waterproofing of Engineering Structures, by W. H. Finley, Journal Western 
Society of Engineers, June, 1912. 

The Waterproofing of Solid Steel Floor R.R. Bridges, Am. Society Civil Engrs., 
Vol. 40, No. 10, Dec., 1914. 

Report of Committee VIII on Masonry, Proceedings Am. Railway Engineer- 
ing Association, Vol. 15, page 569, March, 1914. 

Review of Various Experiences in Waterproofing. " Concrete," April, 1916. 

" Engineering Geology," by Heinrich Reis and Thomas L. Watson. 

The Manufacture of Coke in the United States. U. S. Geologic Survey 
Bulletin, Dept. of Interior, 1913. , 

Formulas and Recipes. 

Henley's 20th Century Book of Formulas and Recipes. 

" Paint Making and Color Grinding," by Charles S. Uebele. 

General Literature on Waterproofing. 

" Masonry Construction," by Ira O. Baker. 

" Building Construction," by Prof. Henry Adams. 

Merriman's " Civil Engineer's Pocketbook." 

Subways and Tunnels of New York, by Gilbert, Wightman and Saunders. 
^ Panama Canal Waterproofing, Engineering News, Vol. 73, No. 5, page 215, 
Feb. 4, 1915. 

Treatise on Arches, by Scheffler. 
+ Impermeable Water Tanks, Eng. News, Mar. 18, 1914, Vol. 71. 


" Lining Rondout Pressure Tunnel," New York, Engineering Record, Dec. 
30, 1911, page 772. 

Grouting Big Savage Tunnel, Using Air, Eng. Rec.. page 728, Dec. 23, 1911. 

Olive Bridge Dam, New York, Eng. Rec., page 385, April 8, 1911. 

Rondout Pressure Tunnel, New York, Eng. Rec., page 315, Sept, 17, 1910. 

Grouting Arches, Hamburg, Germany, Eng. Rec., page 258, Sept. 3, 1910. 

French Methods and Machines, Eng. Rec., page 495, Oct. 30, 1909. 

Foundations in England, Eng. Rec., page 474, April 4, 1908. 

Stopping Leaks, Cincinnati Water Works, Eng. Rec., page 224, Mar. 4, 1905. 

" Grouting a Water-bearing Rock Seam on Catskill Aqueduct," Eng. News, 
Vol. 67, No. 6, page 278, Feb. 8, 1912. 

Test of Watertightness of Concrete Tunnel Lining under High Head, Eng. 
News, Vol. 66 ; No. 24, page 710, Dec. 14, 1911. 

Mixing and Conveying Concrete by Compressed Air, Eng. News, Vol. 66, No. 
6, page 173, Aug. 10, 1911. 

Rondout Pressure Tunnel, New York, Eng. News, Vol. 65, No. 22, page 654, 
Junel, 1911. 

Lining and Grouting a French Railway Tunnel in Water-bearing Material, 
Eng. News, Vol. 62, page 580, Nov. 25, 1909. 

Pumping of Cement Grout into Masonry on the Metropolitan Railway, Paris, 
Eng. News, Vol. 62, page 581, Nov. 25, 1909. 

Grouting a Leaky Tunnel on the Paris, Lyons and Mediterranean Railway, 
Eng. News, Vol. 56, No. 15, page 374, Oct. I'l, 1906. 

" Catskill Aqueduct," by Lazarus White. 



Inspection of Waterproofing for Concrete Work, by Jerome Cochran, Engr. 
and Contr., Vol. 37, pages 370 and 404, April 3 and 10 3 1912. 


Effect of Oil on Cement Mortar, Eng. News, July 4, 1907, Vol. 58, No. 1. 

Efficiency of Cement Joints in Joining Old Concrete to New, Eng. News, 
Dec. 12, 1907, Vol. 58, No. 24. 

Strength of Concrete Joints, Proceedings of Engineer's Society of Western 
Penn., Dec., 1908. 

Lime, Hydrated Lime and Clay. 

" Hydrated Lime," by E. W. Lazell, Ph. D. (1915). 

The Colloid Matter of Clay and its Measurement. Bulletin No. 388, U. S. 
Geol. Survey, Dept. of Interior, 1909. 

Lime: Its Properties and Uses; Circular No. 30, Bureau of Standards, 
U. S. Dept, of Commerce, 1911. 

Metal Sheetings. 

" Harlem River Crossing of the Lexington Ave. Subway." New York Muni- 
cipal Eng. Journal, Vol. 1, No. 6, Dec., 1915. 

Methods of Waterproofing. 

Methods of Waterproofing Concrete, by Richard H. Gaines, Eng. News, 
Vol. 58, No. 13, page 344, Sept. 26, 1907. 

Current Methods of Waterproofing Concrete-covered Bridge Floors, Eng. 
Rec., Vol. 58, page 488, Oct. 31, 1908. 

Waterproofing the New York Subways, Railway Review, Vol. 58, No. 11, 
March, 1916. 

Subaqueous Highway Tunnels, American Society C. E., Vol. 4, No. 9, Nov.> 


Inspector's Pocket Book, by A. T. Byrne. 

Building Mechanics' Ready Reference, by H. G. Richey. 

Sand and Cement. 

Standard Sand for Cement Work, Eng. Rec., July 20, 1907. 

Sands: Their Relation to Mortar and Concrete, Cement Age, July, 1908. 

A Sand Specification and its Specific Application, Proc. of the Amer. Soc. 
for Testing Materials, Vol. 10, 1910. 

The Cement Industry in the United States, U. S. Geol. Survey, Dept. of 
Interior, Bulletin for 1910. 

Brown's " Hand Book for Cement Users." 


Specifications Covering Methods of Waterproofing Engineering Structures 
by Joseph N. O'Brien, Eng. Contr., Vol. 34, page 26, July 13, 1910. 

Specifications for Obtaining Dampproof and Waterproof Substructures, Eng. 
Contr., Vol. 34, page 239, 1910. 

Specifications and Instructions for Waterproofing Metal and Masonry 
Structures, by W. H. Finley, Eng. Contr., Vol. 30, page 289, Nov. 4, 1908, 

Specifications for Waterproofing Concrete Work, by W. H. 'Finley, Proc, 
Natl. Assoc. Cement Users, Vol. 1, page .35, 1905. 


Specifications for Waterproofing Concrete Bridges Chicago and North- 
western Railway, Proc. Natl. Assoc. Cement Users, Vol. 1, 1905. 

Specifications for Waterproofing Bridges in the District of Columbia, Proc. 
Natl. Assoc. Cement Users, Vol. 5, page 146, 1909. 

Specifications for Waterproofing a Pumping Chamber in Ground under 
External Head of Water, Proc. Natl. Assoc. Cement Users, Vol. 5, 1909. 

Specifications for Waterproofing New York Rapid Transit Subway, Proc. 
Natl. Assoc. Cement Users, Vol. 1909, page 237. 

Specifications for Waterproofing Solid Steel-floor R.R. Bridges, Eng. Cont., 
Sept., 1915. 


Methods for Testing Coal tar, etc., by S. R. Church, Journal of Industrial 
and Engineering Chemistry, Vol. 5, No. 3, 1913. 

Specific Gravity, Its Determination, etc., by J. M. Weiss, Journal of Industrial 
and Engineering Chemistry, Vol. 7, No. 1, 1915. 

The Permeability of Concrete under High Water Pressure, Eng. News, 
Vol. 47, No. 26, page 517, June, 1902. 

Paraffin Test as Applied to Bituminous Road Compounds, Eng. News, July 8, 
1911, Vol. 65, page 680. 

Methods for the Examination of Bituminous Road Materials, Bulletin No. 
314, U. S. Dept. of Agriculture, 1915. 

Permeability Tests on Gravel Concrete, Eng. Rec., Sept. 26, 1914. 

Permeability Tests of Concrete, Eng. Rec., Jan. 21, 1911. 

Test of Concrete for Impermeability, Eng. Rec., May 28, 1910. 

Impermeability Tests on Concrete, Eng. News, Nov. 7, 1912. 

Investigation of Impermeable Concrete, Eng. Contr., Feb. 26, 1908. 

Progress Report on Materials for Road Construction and on Standards for 
Their Tests and Use. Amer. Soc. C. E., Vol. 40, No. 10, Dec., 1914. 

The Testing of Materials. Circular No. 45, U. S. Bureau of Standards, 
Dept. of Commerce, 1913. 

Some Practical and Technical Tests on Waterproofing Materials, N. Y. 
Municipal Engineers' Journal, Sept., 1917. 

Waterproofing Fabrics. 

Manufacture, Test and Use of Waterproofing Fabric, Eng. News, Vol. 72, 
Sept. 24, 1914. 

The Waterproofing of Fabrics by Mierzinski. 

Linen, Jute and Hemp Industries; Special Agents Series No. 74, U. S. Dept. 
of Commerce, 1913. 

Waterproofing Instructions. 

Instructions for Waterproofing Concrete Surfaces, by W. J. Douglas, Eng. 
News, Vol. 56, No. 25, page 645, Dec. 20, 1906. 

Directions for the Application of Waterproof Cement Coatings, Eng. News, 
Vol. 57, Jan., 1907, page 247. 

Suggestions for Waterproofing Subways, Public Service Record, Vol. 3, 
No. 7, July, 1916 (Publication of Public Service Commission for 1st District, 
State of New York). 

Popular Handbook for Cement and Concrete Users, by M. H. Lewis, C. E. 

Waterproofing Materials. 

Materials of Construction, by Thurston. 


Absorption, Defined, 7 

of Concrete, 4, 229, 230 
- Raw Fabrics, 256, 257 

Felts, 256, 257 

Stone, 4 

Treated Felts, 256, 257 

Fabrics, 256,257 

Abutments, Protection of, 31 
Acid Treatment, 21 

Sludge Defined, 413 
Acids, Effect of, 29 

in Ground Water, 3 
Actinolite, Use of, 111 
Adhesion between Laps, 46 
Adhesives, 320 
Aggregate for Mastic, 63 

Defined, 413 

Scientific Proportioning, 77 
Air Compressor, Use of, 87 

- Pockets, 23, 47 

Temperature, 28 
Akeley, Mr. C. F., 19 
Albertite Defined, 413 
Alcohol, Specific Gravity, 387 
Alkalies, Effect of, 29 
Alkaline, 3 

Alum, 26, 145, 147, 374 

Defined, 413 

Nature of, 147 

Solution, 28 

Use of, 197 
Alumina, 9 
Aluminum Sulphate, 28 

Stearate, 66 

Am. Ry. Engrs. Assn., 117, 129 

Soc. T. M. Report, 408 
Anthracene Defined, 413 
Arbitrary Selection, 78 
Arches, 32 

Architect's Duty, 25 
Armor Coat, 58 
Asbestine Defined, 413 
Asbestos, 23, 31, 374 

Covered Roofing, 121 

- Covered Sheet Iron, 120, 146 

- Defined, 413 

Felt, Application of, 111 
Defined, 153, 413 

- Saturated, 146 

- Use of, 45, 153 

Fibre, Use of, 63 

- Filler, Effect of, 238, 240 

- Nature of, 153 

Shingles, Application of, 11, 101, 

102, 103 
Manufacture of, 102 

Shredded, 32 

Specific Gravity, 387 

- Use of, 56, 153 

Ash Water Glass Defined, 413 
Asphalt, 32, 145, 146, 147, 374 

- Blown, Use of, 141 

Cement Defined, 413 

Characteristics of, 51 

Coefficient of Expansion, 387 

Containing Pitch, 240 

Consistency of, 49 

- Cutter, 178, 179 

- Defined, 413 

Ductility of, 240 

Effect of Overheating, 49 

Heating Kettle, 175, 174 
of, 49 

Joint Filler, 142 

- Mastic Defined, 413 

Nature of, 154 

Odor of, 49 

Pavement Defined, 413 
Preference for, 52 



Asphalt, Produced, 51 

Publications on, 423 

Putty Defined, 413 

Quality of, 51 

Smoother, 177 

Specific Gravity, 387 

- Use of, 17, 31, 32, 154 

Versus Coal-tar Pitch, 51 
Asphaltenes Defined, 413 
Asphaltic Coal, 414 

Concrete, 414 

- Defined, 413 

Limestone Defined, 414 

Oils Defined, 414 

Petroleum Defined, 414 

Sandstone Defined, 414 
Asphaltite Defined, 414 
Asphaltum Defined, 414 


Backfill, 13, 39, 40 
Bacterial Decomposition, 8 
Bakelite, 146, 147, 414 

- Use of, 154 
Bank-run Gravel, 78, 414 
Barrels, Cost of, 373 
Barret Specification Felt, 414 
Basement Waterproofed, 365 
Bats, Use of, 56 

Battens, Use of, 114 

Baume Table, 381, 382, 383, 384, 385 

Gravity, 414 

Beeswax Specific Gravity, 387 

Coefficient of Expansion, 287 
Benzene Defined, 414 
Benzine, 145, 147 

Cost of, 374 

- Defined, 414 

- Use of, 155 
Benzol, Cost of, 374 

Defined, 414 

- Use of, 155 

Bergen Hill Tunnels, 335, 336 
Bermudez Asphalt Defined, 414 
Binder, 32, 414 
Bitumen, Artificial Defined, 413 

Defined, 414 

for Mastic, 62 

Ready Roofing, 112 
Transportation, 50 

Bituminous Binder, 34 

Blanket, 31 

Cement Defined, 414 

Coat Applied, 24' 

Compound, Use of, 16, 29, 46, 146 

- Defined, 414 

Emulsion Defined, 414 

- Enamels, 29 

- Fillers, 142 

Mastic, 29, 52 

- Paint, 18, 29, 142, 147, 155, 414 

- Paste, 29, 31 

- Putty Defined, 414 

Rock Defined, 414 
Bleeders, Use of, 58 
Blistering, 20, 26 
Block Tin, Use of, 108 
Blow H61es, 34 

Blown Asphalt, Use of, 143, 414 

Oil Defined, 414 

Petroleum Defined, 414 
Board Sheathing, 308 
Bond, Effect of Surface, 249 
Bonding Fabrics, 47 

- Day's Work, 70 
Boston Tunnels, 337, 338 
Brick, Absorption of, 4 

Applied, 56 

- Bond, 249 

Compression of, 249, 250 

Cost of, 374 

Courses, 57 

Function of, 56 

- Heating Methods, 65, 66, 183, 373 

- in Mastic, 52, 53, 54, 56, 57, 63, 146, 


- Parapet, 118 

Protective Medium, 37 

Quality of, 61, 63 

Roof Domes, 92 

Sewers, 20 

Soot Covered, 65 

Specific Gravity, 4, 387 

- Walls, 58 
Bridge Floors, 67 

Waterproofed, 53 
Bronze Plate Roofs, 92 
Brooklyn Railroad Viaducts, 34 
Broom, Cost of, 373 
Bubbles in Mastic, 62 



Buckets, Use of, 50 
Building Foundations, 32 

Paper Denned, 414 

Built-up Roofs, 92, 108, 308, 310, 415 

Membrane, 31, 45 

Bulge in Mastic, 61 
Burlap, Use of, 47, 155, 375 

Denned, 415 

- Membrane, Weight of, 388 
Butt Joints, 43 
Byerlite Denned, 415 

Caffall Process Defined, 415 
Caisson Cross-section, 292 
Calcium Compounds, 9, 66, 75, 147, 
148, 415 

Minerals, 146, 147 

Oxide, 8 

Sulphate, 8 
Calking Joints, 144 

- Tunnels, 366 

Caoutchouc, Specific Gravity, 387 

Defined, 415 

Capillary Passageways, 7, 19, 47 
Carbenes Defined, 415 
Carbolineum, 93 
Carbon Bisulphide, Defined, 415 

Disulphide, Defined, 415 

Tetrachloride, Defined, 415 
Carborundum, 231, 415 
Casein, Defined, 415 

- Use of, 148 

Cast-iron Tunnel Segments, 363 

Use of, 146, 147, 156 
Cast Steel, 146 

Castor Oil, Specific Gravity, 387 
Catskill Aqueduct, 87, 359 
Caustic Potash, 145, 147, 148, 374 
Cedar, Specific Gravity, 387 
Cells in Concrete, 7 
Cement, 145, 375, 415 

Additions to, 409 

Benzine Resisting, 318 

Coating, 147 

Coefficient of Expansion, 387 

Effect of Alkali, 405, 407 
Fineness, 76, 77 

- Water, 403, 407 
Wetting, 77 

Cement, Excess, 77 

Floor Defined, 415 

- for Mastic, 318 

Grouting, 85 

-Gun Operation, 19, 20, 184, 185, 
186, 373 

Hydration of, 77 

- Mortar, Use of, 156, 16 

Petroleum Resisting, 318 

Publications on, 426 

Quick-setting, 85 

Specific Gravity, 387 

- Tiles, 97 
Cerasin Defined, 415 
Cerite Defined, 415 
Charcoal, 29 
Cheese, Use of, 144 

Chemical Acting Materials, 146, 147 
Chimneys, Flashing for, 117 
China Clay, 72, 415 

- Wood Oil, Defined, 415 

Specific Gravity, 387 

- Use of, 31, 143, 148 
Chipping of Surface, 21 
Chloride of Lime, 74 
Choctow Defined, 415 
Cinder, Concrete Absorption, 4 

Specific Gravity, 4 
Cisterns, 24 

Civilization, Measure of, 2 
Clay, 66, 75, 415 

- Oil-joint Filler, 142 

Publications on, 426 

Specific Gravity, 387 

- Tiles, 95, 96 

-Use of, 26, 71, 72,91, 156 
Clay-cement Waterproofing, 365 
Cleats, Use of, 108 
Climate, Consideration of, 31 
Clinker, 72 
Coal Tar Defined, 415 

- Pit Waterproofed, 366 
Coal-tar Pitch, 32, 146, 147, 374 
Characteristics of, 49, 51 

Defined, 415 

Joint, Filler, 142 

Overheating, 49 

Produced, 51 

Versus Asphalt, 51 
Products, 31, 75 



Coal-tar Pitch, Use of, 31, 49, 157, 164 
Coat Defined, 415 
Coating Continuous, 30 

on Felts, 252, 253 

Fabrics, 252, 253 

Coatings, Application of, 21 

Applied by Brush, 19 

Machine, 19 

Trowel, 19 

Continuity of, 19 

Coefficient of Expansion, 12, 124, 125 

of Materials, 387 

Coke Oven Tar Defined, 415 
Coking of Bitumen, 49 
Colloidal Clay, 71, 146, 147 

Matter, 75, 415 
Colophony Defined, 415 
Column Bases Waterproofed, 11 
Composite Roofing, 120, 122 
Composition Roofing, 92, 108 
Compounds, Effect of Earth, 29 

^Backfill, 29 

Compressed Asphalt Defined, 416 
Compression of Brick, 249 

Mastic, 249 

Membrane, 260 

Mortar, 249 

Concrete, 374 

Absorption of, 3, 4 

Additions to, 409 

Age, 2 

Atomizer, 89, 90 

Average Weight of, 4 

Coefficient of Expansion, 387 

Consistencies, 78 

Cutoffs for, 137 

Effect of Alkali, 405, 407 

Floor Hardener, 319, 416 

Hand Mixed, 77 

in Sea Water, 403, 406, 407 

Machine Mixed, 77 

Parapet, 118 

Pipe Joints, 137, 138 
Reinforcement, 82 

Porosity of, 7, 77 

Primer Defined, 416 

Protective Coat, 37 

Publications on, 423 

Railroad Details, 343 

Reinforcement, 125 

Concrete Roof Slab, 310 

- Roofs, 123 

Safeguarded, 9 

Specific Gravity, 4, 387 

Standpipe, 331 

Tampers, 181, 182 

Tank Waterproofed, 356 

- Tile, 95, 96, 97, 98, 99, 100, 229, 230 

Time of Mixing, 99 

Universal Material, 3 
Conglomerate, Absorption of, 4 

Specific Gravity, 4 
Consistency Defined, 415 
Construction Joints, 14, 38, 128 
Efflorescence, 14 

Shaft, 83 

Contractors, Graded, 370 
Copal Gum, ,72 
Coping, 117 

Copper Bulb Joint, 134 

- Cutoffs, 134 

Sheeting, 105, 108 

Specific Gravity, 387, 393 

V- Joints, 131 
Cord Wood, 373 
Cores, 48 

- Fabric Roll, 182 

- Felt Roll, 182 

- Illustrated, 183 
Corrosion, 2 

of Metallic Powders, 27 
Corrugated Roofing, 121 

Sheet Iron, 120, 393 
Corundum Defined, 415 
Cost Data, 371, 372 

- Low First, 145 

of Materials, 374 

Implements, 373 

Labor, 372 

Tin, 378 

Waterproofing Applied, 376, 377 

Cotton, Drill, Use of, 34, 46, 48, 157, 
375, 416 

Fabric, 45, 46, 47 

Membrane, 388 

- Roofing, 111, 120 
Cove Finish, 53 
Cracked Oil Defined, 416 
Cracking, 20, 416 
Cracks, Prevention of, 125 



Cracks, Cause of, 67 
Creosote, 93 

Oil, Application of, 31 
Crude Tar De ined, 416 

Asphalt Defined, 416 

Oil Defined, 416 
Crumbling Palisades, 8 
Cube in Air Method, 198 

Water Method, 198 

Curing, 26 

Cut-back Pitch, 111 

Products Defined, 416 

Cutoff, Use of, 134 

Wall, 17, 83, 85 
Cutters, 178, 373 
Cypress Shingles, 92 


Dam, Ashokan, Cutoff, 358 

Waterproofed, 325 
Dampproof, 13, 16 
Dampproofing Compounds, 29, 314 

Defined, 416 

Publications, 424 

Walls, 16, 316 
Davit Attachment, 174 
Day's Work Joint, 128 
Plane, 68 

Dead Oil Defined, 416 
Dehydrated Tars, Defined, 416 
Dense Concrete, 77, 78, 80 
Density, 3 

Effect of, 67 

Factors, 76 
Depressions in Surface, 33 
Design Details, 81 

Destructive Distillation Defined, 416 
Development of Waterproofing, 1 
Dike Form Joint, 339 
Dipper, 167, 177, 373 
Dipping Compound, 416 
Disintegrating Effect, 2, 8, 26 
Drain Pipes, 6 
Drainage, 5, 6, 134 

Defined, 416 

System, 33, 349 

Drop Point Apparatus, 207, 208 
Dry Spots, 34 

Ply, 33, 54, 58 

Surface, 26, 33 

Drying, 26 

Oven, 214 

Dual Subways in N. Y. C., 54 
Ductility of Asphalt, 240 . 

Relation to Temperature, 246 
Dust Defined, 416 
Dwellings, Concrete, 2 


Earth Excavation, 58 
East View Tunnels, 331 
Eastern Petroleum Defined, 416 
Efflorescence, 6, 12, 14 
Egyptians Practice Waterproofing, 1 
Elastic Membrane, 31, 45 
Elaterite, Use of, 145, 147, 157 
- Defined, 416 
Electric Oven, 213, 373 

Resistance, 10 
Electricity, Effect of, 9 
Electrolysis, 4, 9, 10 

Publications, 424 
Emulsion Defined, 416 
Enamels, 145 

Engineering and Contracting, 8, 369 
Engineering News, 325, 328, 334, 337 
Engineering News-Record, 85, 322 
Engineering Record, 337, 352 
Equipment for Grouting, 86 
Estimates, 368, 369 
Evaporating Oven, 214 
Examples of Membrane Application, 331 

Grouting, 357 

Integral Application, 356 

Mastic Application, 353 

Self-densification, 356 

Special Waterproofing, 360 

Excavating Foundations, 29 
Excess Cement, 26, 70 
Expansion Joint, Basic Types, 129 
- Cutoff, 136 

Defined, 416 

Design of, 126 

Drain Pipe, 138 

Effect of, 12 

Fillers, 129 

Function of, 124 

Illustrated, 130 

Properties of, 124, 128 

Reinforced, 135 



Expansion Joint, Sliding, 138, 139 
Spacing of, 126 

Waterproofed, 135 

Expansive Force of Freezing Water, 7 

Concrete, 7 

Exterior Applications, 29 
External Cutoffs, 134, 139 
Treatments, 410, 411, 412 
Exudation of Lime Salts, 15 

Fabrics, 34, 48, 146, 374, 416 

Membrane, 52 

Fats, Specific Gravity, 387 

Fattening Materials, 146 

Feldspar, 66, 71 

Felt Joint Protection, 132 

Felts, 32, 34, 46, 47, 48, 146, 158 

Cost of, 374 

Defined, 416 

Flashing, 119 

Membrane, 31, 52, 388 

Roofing, 92, 108, 109 

Weight of, 379 
Ferrules, Use of, 349 
Fillers, Analysis of, 72, 73 

Defined, 416 

Use of, 62, 66, 72 
Film, Continuous, 30 
Finial Tiles, 98, 99 
Finishing Coat Applied, 22 
Fire in Kettles, 50 

Wall Flashing, 16 
Fireproof Liquids, 93 
Fireproofing, 16 
Fish-oil, Use of, 72, 75 
Fissured Rock Solidified, 83 
Fixed Carbon Defined, 416 
Flashing, 116, 117, 118, 416 
Flat Roof, 92, 110 

Seam Roofing, 106, 108 
Floating Defined, 417 

Mortar Surface, 20 
Floats, 182, 183 
Flood Water, 5 
Floor Joint Filler, 144 

Hardener, 27, 231, 232, 233 
- Treatments, 319 

Waterproofing, 53 
Flow Point Apparatus, 209 

Flux Defined, 417 

Foreign Substances, Addition of, 67, 409 
Foreman of Waterproofers, 372 
Forms for Post Holes, 56 

Armor Coat, 59 
Bracing, 60 

Filling, 59, 61 

Setting up, 59 
Formulas, Special, 313 

Publications on, 425 
Foundation of Pyramids, 1 

-Walls, 29 

Frea's Electric Oven, 213 
Free Carbon, 214, 215, 216 

- Defined, 417 

Freezing Effect of Water, 2, 7 
Fuel Material, 29, 50 
Fullers' Earth, 80, 417 
Functional Roofing, 92, 120, 123 
Fundamental Waterproofing Require- 
ments, 33 
Fumes, 49 
Furring Compounds, 417 

Gable Roofs, 92 
Gas Black, 417 

Drip, 36, 417 

- House Coal-tar, 417 

- Main, Effect of Leaks, 36 

- Oven, 214 
Gaskets, Use of, 129 

Gasoline, 31, 57, 147, 158, 374, 417 

- Torch, 33, 178 
Gauging Water, 417 
Gelatinous Compound, 75, 146 
General Electric Method, 198, 205, 206 
German Wax Defined, 417 
Gilsonite, Defined, 413, 417 

- Use of, 143, 147, 159. 374 
Glance Pitch Defined, 417 
Glass Roofing, 120, 122 

Specific Gravity, 387 
Glossary of Terms, 413 
Gooch Crucible, 193 
Government Publications, 313 
Grading, Laws of, 67, 80 
Grahamite, Defined, 417 

- Use of, 147, 159 
Granite, Absorption, 4 



Granite, Specific Gravity, 4, 387 
Granolithic Finish, 20, 24 
Graphite, Defined, 417 
Specific Gravity, 387 

- Use of, 146, 147, 159, 375 
Gravel Concrete, 78 

Absorption, 4 

- Defined, 417 

- Heater, 175, 181 

Roof Covering, 109 

Specific Gravity, 4, 147, 375 

- Use of, 159 
Grit Defined, 417 

Ground Water, Depth of, 2, 5, 52 

- Defined, 417 

Effect on Concrete, 5 

- Fabric, 255 
Grout, 82, 145, 147, 417 
Grouting Machine, 186, 187, 373 

Materials, 146 

- Process, 17, 82, 84, 87.. 88, 359, 417 
Publications, 425 

Gum Defined, 417 

Gumlac Defined, 417 

Gunite Defined, 417 

Gutta Percha, Specific Gravity, 387 

- Defined, 417 
Gutters, 118, 120 

Gypsum, Specific Gravity, 387 

- Defined, 417 


Hail, 5 

Hair Checks, 26 

Hard Soap, 28 

Harlem River Tunnels, 360, 361 

Harris, Mr. Robert L., 83 

Headers, 61 

Heat, Effect on Pitch, 236 

- Linseed Oil, 236 
Heating Kettles, 50, 170, 171, 173 

- Pan, 178, 180 
High Carbon Tars, 418 
Horizontal Joints, 128 
Hot Stuff Defined, 128 
Hudson-Manhattan Tunnels, 330, 365 
Hydrated Lime, 66, 67, 146, 147, 375, 


Composition, 71, 418 

Proportion, 70 

Hydrated Lime, Specific Gravity, 7, 83 

- Use of, 69, 148 
Magnesia, 9 
Hydration of Mortar, 20 
Hydrocarbons, 23, 145, 418 
Hydrochloric acid. 72 
Hydrogen Sulphide, 8 
Hydrolitic Defined, 418 
Hydrolithic Defined, 418 
Hydrostatic Head, 5, 36 
Hydrex Compound, 418 
Hygienic Effect of Waterproofing, 13 

Ice, Specific Gravity, 387 
Ideal Mix, 80 
Imitatite Defined, 418 
Immutability Test, 260 
Impervious Roofing, 93, 94, 118 

Coatings, 19 
Imperviousness Essential, 81 
Implements, Sundry, 166, 176 
Impsomite Defined, 418 
Inert Fillers, 23, 70, 71 
Inspection of Waterproofing, 372, 426 
Integral Liquids, 15, 25, 28, 74, 75, 


System, Materials for, 69, 146 

- Purpose of, 17, 66, 67, 68, 418 
Interior Applications, 29 
Internal Cutoffs, 134, 137 
Iron Borings, Use of, 143 

- Cutoffs, 134 

- Oxide, 27 

-Powdered, Use of, 146, 147, 149, 
375, 418 

Sheeting Thickness, 394 

Specific Gravity, 387, 393 
Isinglass Defined, 418 

Joining Membranes, 34 
Joint Baffle, 131 

- Barrier, 133 

- Fillers, 140, 141, 142, 426 
Chemical Acting, 143 

- Defined, 418 

- Rolls, 129, 131 
Joints, Effect of, 42, 43 
for Bridges, 133 



Joints, Effect of, Abutments, 133 

in Brick Masonry, 126 

Concrete, 62 

Forms, 61 

Membrane, 34 

Jute Fabric, Use of, 46, 47, 48, 111, 160 


Kalinite, 147 
Kaolin Defined, 418 
Kauri Gum, 72 
Kerosene, 29 
Kettlemen, 372 
Kettles, 50, 54, 179, 373 
Knot Hole Fillers, 144 

Care of, 114 
Knowledge of Materials, 2 
Kraemer & Sarnow Method, 198 

Labor, 27, 146, 370, 372 
Lake Pitch Defined, 418 
Land Pitch Defined, 418 

Plaster Defined, 418 
Lap, Cement, 418 

Sealed, 46 

Width of, 34 
Larutan System, 418 
Layer, Defined, 418 

Type of Membrane, 41 
Leaching, Effect of, 141 
Lead Cutoffs, 134 

Sheet, Use of, 92, 365 

Sheet Thickness of, 393, 394 

Specific Gravity, 387, 393, 394 

Wool, Use of, 144, 375 
Leaks, Occurrence of, 110 
Lean Mixtures, 20 

Mortars, 25 

Lime, 19, 75, 145, 149, 375, 418 

Specific Gravity, 387 

Stearate, 66 

Washes, 61 
Limestone, Absorption, 4 

Dust, 62, 375 

Specific Gravity, 4, 387 
Linseed Oil, 93, 145, 147, 375, 418 

and Pitch, 236, 237, 238 

Specific Gravity, 387 

Linseed Oil, Paints, 18 

- Use of, 31, 149, 143 
Literature on Waterproofing, 1, 426 
Lithocarbon Defined, 418 
Long Island Railroad Subway, 332 
Low Carbon Tars, 418 
Lubricant Action, 69 
Lubricants, Function of, 67 
Lubricating Oil, 36 
Lye, Concentrated, 28 


Mabery-Sieplein Method,.198, 202, 203 
Machinery, 166 
Magnesium Chloride, 9 

Oxide, 8 

Sulphate, 3, 8, 9 
Maltha Defined, 418 
Malthene Defined, 419 
Manhattan-Bronx Subway, 333 
Manhattan Railroad Viaducts, 341 
Manhole, 20 

Marble, Absorption, 4 

Specific Gravity, 4 
Martin's Creek Viaduct, 339 
Masonry, Specific Gravity, 387 

- Solidified, 83 

Treatments, 314 
Mastic Bond, 249 

- Defined, 419 

Heating Kettle, 64, 175 

Joint Filler, 142 

- Materials, 53, 62, 168 

- Mixing Kettles, 64, 65, 166, 167, 168, 

169, 170, 373 

Properties, 242, 247 

Roof Flashing, 142 

Sheet, 52, 53, 54, 56 

Stirrers, 177 

System of Waterproofing, 17, 52 

Trowel, 183 

- Use of, 57, 63, 64, 145, 147, 161 

Volume, 62, 248, 390, 391 

Wall, 61 

- Weight, 390, 391 

Mat, Expansion Joint, 139 
Materials for Calking, 143 

Grouting, 85 

Manjak Defined, 419 
Meandering Cracks, 127 



Mechanical Acting Materials, 146, 147 

Analysis, 80, 399 

Melting Point Methods, 197, 235, 236 
Membrane, Application of, 32, 40, 42, 

Continuity, 33, 34, 40, 41 

Defined, 419 

Materials, 146 

Mats, 34, 42 

Protection of, 34, 35, 36, 37 

Reinforcement, 46 

Sheet Lead, 37 

System of Waterproofing, 17, 31, 


Mesh Joint, 34 
Metal Flashing, 101, 107, 117 

- Linings, 31, 33 

Primer Defined, 419 

Shingles, 120 
Metallic Compounds, 23 
Metals, 146, 426 
Mineral Aggregate, 62, 146 

- Fillers, 32 

Matter, 143 

- Naphtha, 419 

Oil, 419 

- Pitch, 419 

- Rubber, 419 

Surfacing, 100 

Tar, 419 

- Wax, 419 
Minwax Defined, 419 
Missouri Clay, 71 
Mixing Methods, 5, 81 
Mixtures of Soap and Alum, 23 
Modulus of Elasticity, 12, 125 
Moisture Absorption, 15 
Monolithic Construction, 125 
Mops, 176, 373 

Mortar, 23, 25, 26, 82 

Defined, 419 

Joints, 126, 127 

Porosity of, 27, 77 

- Protective Coat, 18, 37, 38 

Specific Gravity, 387 

Tiles, 95 

Trowel, 183 
Muriatic Acid Applied, 21 
Mushy Concrete, 78 


Nailheads Covered, 101 
Nailing Base, 94 
Nails, Use of, 93, 101, 397 
Naphtha, Coal-tar, 23 

Defined, 419 

- Use of, 31, 145, 147, 161 
Naphthaline Defined, 419 
Natural Asphalt, 146 

Cement, 72, 146, 147, 149, 419 
Native Bitumen, 419 

- Paraffin, 419 

Neat Cement, 82, 145, 146, 147, 150 
Necessity of Waterproofing, 1 
Neponsit Felt Defined, 419 
Neutral Oil Defined, 419 
New York Board of Water Supply, 86 

Clay, 71 

- Dual Subways, 334, 353 

Municipal Railway Corp, 343 

Testing Laboratory Method, 198, 

Oak, Specific Gravity, 387 
Oil Asphalts Defined, 419 

Compounds, 66 
- Effect of, 36 

Emulsion, 74 

Gas Tar Defined, 419 

Specific Gravity, 387 

Tester, 192 

Oil-tar Pitch, 146, 147, 161, 375, 419 
Old Laps, 34 
Oleate Pctassium, 66 

Sodium, 66 

Oxidation of Reinforcement, 9 
Ozokerite Defined, 419 
Ozocerite Defined, 419 

Paddle Mixing Machine, 86 
Pails Pouring, 167, 177, 178, 373 
Painting, 18 
Paints, 145 

Paint-spraying Machine, 19 
Paper Burlap, Use of, 162 

Rosin-sized, 108 

Saturated, 146 

Use of, 32, 162 



Parabola, Sand Curve, 81 
Paraffin Defined, 419 
Paraffine Defined, 419 

Naphtha, 419 

- Oil, Use of, 163, 419 

Solution, 72 

Specific Gravity, 387 

- Use of, 23, 28, 29, 145, 147, 162, 375 
Parapet Walls, 116 

Patented Cements, 23, 146 

Compounds, 145, 146 
Peeling of Stucco, 20, 26 
Pellet Method, 204 
Penetrometer, 196 

Penetration and Temperature, 244, 


Pennsylvania Railroad Tunnels, 335 
Percolation Defined, 7 
Permeability Defined, 7 

- Effect of, 67 

Test, 220, 221, 222, 223, 224, 226, 

227, 228 

Persulphate of Iron, 93 
Petrolene Defined, 420 
Petroleum Defined, 420 

Grease, 143 

- Oil, 23, 146 

Specific Gravity, 387 
Petrolic Ether, 420 

Pig Iron, Use of, 23, 143 

Pine Oil, 420 

Pine, Specific Gravity, 387 

-Tar, 31, 142, 420 

Pitch, Asphalt Mixture, 111, 238, 239 

- Defined, 420 

Linseed Oil Mixture, 236, 237, 238, 


of Roofs, 104, 105 

- Quality of, 49, 51, 52, 146 

Specific Gravity, 387 
Pipe, Coating, 420 

Grouting Process, 86 

Mineral Heating, 181 
Plane of Weak Bond, 127, 142 
Planning and Estimating, 368 
Plaster Bond, 420 

of Paris, 33, 58, 111, 420 

Specific Gravity, 387 
Plastering, 16, 18 
Plastic Clav. 133 

Plastic Roofing, 420 

Slate, 142, 420 
Plasticity of Bitumen, 32 
Plate Steel, 147 

Plies, Adhesion Between, 34 

Pointing Mortar, 126 

Porosity, 3, 7, 78 

Portable Kettles, 50 

Portland Cement, Use of, 24, 71, 73, 

74, 146, 147, 150, 420 
Post Holes Treated, 43, 44, 57 
Potash, 26 

Pouring Pail, 167, 177, 178, 373 
Powdered Metals, 27 
Powders Finely Ground, 66 
Practical Tables, 379 

- Tests, 26, 188, 229 
Precast Joint Filler, 128 
Preparation of Surface, 57, 58 
Prepared Roofing, 112 

Shingles, 100, 101, 113 
Preserving Concrete Tanks, 317 

Liquids, 93 

Processes, 18 
Pressure Tunnels, 357 
Priming Coat, 30, 420 
Proportioning by Eye, 64 

- Effect of, 67 

Soap and Alum, 28 
Proprietary Compounds, 18, 72, 146 
Protective Concrete, 32, 36, 37, 56, 78, 


Quaking Consistency, 27 

Quasi, Colloidal Bodies Defined, 420 

Soap Bodies Defined, 420 
Quick Lime, 67 


Rag Felt, 32 

Railroad, Concrete Roadbed, 346, 347 

Drainage, 6 

Mezzanines, 344, 345, 347 

Viaduct Waterproofed, 337 
Joint Filler, 346 

Rain, 5 

Ready Roofing, 112, 114 
Recipes, Practical, 313, 425 
Red Rope Paper, 420 



Heduced Oils, 420 

Petroleum, 421 
Redwood Shingles, 92 
Refined Asphalt, 421 

Tar, 421 

Reinforced Filter Plant, 356 

Reservoir, 356 

Standpipe, 351 

Water Tank, 357 
Reinforcement Oxidation, 9 
Report on Waterproofing, 408 
Reservoirs, 13, 32, 329 

Gate House, 325 
Residual Oil, 421 

Petroleum, 421 

- Tar, 421 
Resin, 151, 421 
Resinates, 67 

Retaining Walls, 20, 31, 32, 325 

Rich Mortar, 25 

Richardson Method, 198, 204 

Ridge Roll, 104 

Roadbeds Waterproofed, 353 

Rock Asphalt, 421, 52 

Excavation, 58 
Roman Waterproofing, 1 
Rondout Tunnels, 358 
Roof Drainage, 118 

- Gutters, 119 

Joints, 106 

Simplest, 91 
Roofers, 372 

- Kettles, 172, 173 
Roofing, 91, 110, 319, 426 

Cement, 319, 421 

Cost of, 91 

German, 96 
-Gravel, 110,421 

Modern, 92 

- Mops, 176 

- Nails. 397 

- Paper, 319 

Selection, 91 
-Slag, 109, 110,421 

Spanish, 96 
Roofs in Tropics, 92 
Rosin, 145, 147, 421 

Specific Gravity, 387 
Rubber, Specific Gravity, 387 
Rust Joint, 144 


Salamander, 33, 65, 181, 373 
Sal ammoniac, 146, 147, 151, 421 
Sanborn, Mr. James F., 89 
Sand, 25, 50, 62, 71, 80, 85, 147, 375, 
421, 426 

- Cement, 24, 85, 147, 151, 421 

- Drying, 179, 180 

- Heating, 181 

- Wall, 58, 60 

Sandstone, Specific Gravity, 4, 387 
Saturant in Felts, 252, 253 

- Fabrics, 252, 253 
Sawdust, 375 

Scientific Proportioning, 3, 78 
Scratch Coat, 22 
Screenings, 402 
Scuttle, 373 
Sea Wall Coatings, 24 

- Water, Effect on Concrete, 4, 8 
Seasoning Concrete 

Secret Compounds, 145, 146, 165 

Seepage, 12 

Self-densified Concrete, 17, 68, 76 

Materials, 146 
Semi Asphaltic Oils, 421 

Petroleum, 421 
Service Tests, 26, 323 
Sewage, Effect on Concrete, 8 
Sewer Leakage, 35 
Shale Tiles, 95 
Sheathing, 146 
-Boards, 92, 100, 114 

- Paper, 109 

Sheet Copper, 94, 97, 146 

- Iron, 123, 146 

- Lead, 37, 45, 94, 104, 105, 132, 146 

- Mastic, 38, 52, 53, 146, 421 

- Metal, 147, 393 

Piling, 58 

Tin, 146 
Shingle Roof, 92 

Shingles, 92, 93, 101, 104, 396 
Methods of Applying, 102, 103, 104 
Short, Defined, 421 
Shovel, 373 
Sieves, 400 
Silicates, 66 
Silt, Effect of, 125 
Slack Barrels, 373 



Slag Cement Mortar, 24 

Roofing, 94, 109, 308, 310 
Slate, Powdered, 31, 63, 111 

Shingles, 93 
Slates, 4, 387, 397 

Slip, Tongue Joint, 127, 128 

Slush Coat, 22 

Smith Ductility Machine, 211, 212 

Smoother, 46, 177, 178, 373 

Snow, 5 

Soap, 28, 66, 74, 145, 147, 151, 375, 421 

and Alum, Action of, 28 
Soda Ash Defined, 421 
Sodium Chloride, 9 

Fluoride, 93 

Silicate, 93 

Sulphate, 83 
Softening Point, 207, 208 
Soils Solidified, 83 
Solvent, Effect of, 28, 29 
Soluble Glass, 421 
Spading, 3 

Spalls, Use of, 56 
Special Cements, 146 

Membrane, 45 

Specific Gravity of Concrete^ 4 
of Materials, 4, 387 
Coal-tar Pitch, 197 

Petroleum, 197 

and Baumc, 381, 382, 383, 384, 


Resistance of Concrete, 10 

of Mortar, tO 

Specifications, 426 

- Asphalt, 267, 268, 269 
-Bridge, 298, 299, 300, 301, 302 

Caisson, 291 

Coal-tar Pitch, 269, 270 

Concrete, 273, 305 

Creosote Oil, 270 

Dampproofing, 273 

Fabric, 263, 265, 266 

Felt, 264, 

Floor, 303> 3Q4 

Foundation, 278 

Hydrated Lime, 271, 272 

Integral System, 274 

Masonry, 273 

Mastic Pitch, 270 

Material, 263 

Specifications, Railroad Structures, 
293, 294, 295, 296, 297 

Requisites, 262 

Roof, 206, 207, 209, 306, 311, 312 

Stucco, 277 

Substructure, 279 

- Subway, 280, 281, 282, 283, 284, 285 r 

Surface Coating, 275, 276 

- Tunnels, 280, 287, 288, 289, 290 

- Waterproofing, 273 

Writing, 263 
Spruce Shingles, 92 
Staggered Type Membrane, 41 
Standard Methods for Bridges, 294 
Standing Seam Roofing, 106, 108 
Staves, as Fuel, 50 

Steam as Fire Extinguisher, 50 

Insulation, 45 

Steam-pressure Placing Machine, 89 
Stearates, 28, 67, 72, 75, 143, 146, 147, 

152, 153, 421 

Steel Plate, Use of, 163, 146, 367, 387, 

Reinforcement, 12 
Stirrers, 177, 373 

Stone Aggregate, 78-, 80; 163 

Average Weight, 4 

Duplication of, 3 

Preserving Composition, 316 

Screenings, 86,147, 374 

- Slab Roof, 92 
Storing, Effect of, 48 
Structural Bodyguard, 2 
Structures, Bane of, 3 
Stucco, 25 

Subaqueous Tunnels, 362 
Subsurface Structures, 350 
Subway Asphalt, 421 

- Pitch, 421 

Subways, 7, 32, 47, 48, 55, 354 
Suet, 145, 147, 153, 421 
Sulphuric Acid, 8 

Anhydride, 8 

Supervision, Effect of, 3, 45, 76, 77, 81 
Surface Coating Compounds, 23, 25, 

30, 72 
System, 9, IT, 18> 19, 26, 145, 315, 

323, 421 

Preparation, 33, 58 



Swimming Pool, 20, 25, 352 

Switch Pits, 36 

Sylvester Process, 17, 28, 421 

Tables, Explanation of, 379, 386 

Tallow, Specific Gravity, 387 

Tamper, 373 

Tank Treatments, 24, 317 

Tar and Gravel Heater, 175, 174 

- Use of, 141, 145, 147, 164, 422, 423 
Technical Tests, 188 
Temperature, Effect of, 2, 4, 11, 125, 

241, 251 
Tensometer, 210 

- Mold for, 211 
Terne Plate, 105 
Terra Cotta, 37, 58, 387 
Terrazzo Floor, 231 
Tests, Asphalt, 189 

-Determination, 190, 191, 192, 194, 
195, 198 

Drop Point, 205 

- Ductility, 209 

- Flash Point, 191 

Flow Point, 208 

- Identification, 212, 213, 217, 218 

- Practical, 219, 229, 231, 234 

Publications on, 426 

Specific Gravity, 190 

- Waterproofing, 188, 189 
Texene, 422 

Thatch Roof, 91 
Thawing, Effect of, 2 
Thermometric Equivalents, 380 
Thompson, Sanford E., 69 
Tiles, 52, 99, 146, 387 

Shingles, 95 
Timber, Use of, 22, 50 
Tin, 384, 393, 394 

- Cutoffs, 134 

Drain, 33 

Flashing, 94 

Plate, 105, 106, 108 

- Roofing, 92, 105, 108 
Tongue and Groove Joints, 133 
Tools, Applicability of, 166 
Torch, 57, 178, 373 
Torpedo Gravel, 422 

Trap, Specific Gravity, 4 

Treated Materials, 147 

Trial Mixtures, 80 

Trinidad Asphalt, 143, 422 

Trough, 58 

Trowels, 182, 373 

Tunnels, Grouted, 83 

Penn. Railroad, 20, 29, 31, 32, 33, 

39, 326, 327 
Turpentine, 375, 387 
Tun-eUite, 422 


Ultimate Tensile Strength, 12, .125 
Uneven Settlement, 2, 4, 13 
United States Bureau of Standards, 8, 

27, 68, 69, 71, 74 
Capital Terrace, 340 

Varnish Gum, 422 

Vibration, Effect of, 13, 67 

Vintaite Defined, 422 

Viscosity, 422 

Viscous Priming Coat, 30 

Vitrified Tibs, 6, 45 

Voids, Determination of, 7, 78 

- Filling Materials, 3, 146 
Volatile Defined, 422 

Oil, 49 
Volumetric Synthesis, 80 

Tests, 80 


Walls, 58 
Water, 147 

Absorbent, 422 

- Diverted, 84 

Effect on Fabrics, 254 

Ejecting Grout Machine, 87 

Evaporation, 77 

Gas Tar, 164, 422 

Glass, 75, 422 

Repellent, 3, 67, 422 

Pressure, 18, 63, 392 

Specific Gravity, 387 

Storage Works, 323 

- Table, 5, 422 

Universal Solvent, 1 

- Use of, 22, 50, 99, 164 

Works Reservoir, 328, 360 



Waterproofers, Graded, 370, 372 
Waterproofing, Adaptability, 82, 422 

Applied, 323 

Art of, 1 

Cements, 320, 321 

Compounds, 313, 314, 321, 322 

Economy, 16 

Fabrics, 426 

Failures, 124 

Implements, 166 

- Materials, 145, 389, 426 

- Mortar, 314 

Paste, 72 

Progress, 17 

Projections, 43 

Publications, 425 

Roof Coverings, 395 

Specifications, 262 

Steampipes, 43 

Systems, 17 
Watertight Roofs, 91 
Wax, 387 

Weak Bond Plane, 133 
Weather and Waterproofing, 66 
Weep Holes, 6 

Weight of Implements, 373 

- Materials, 374 
Wet Surface, 66 
Wheel Barrow, 181, 373 
Wood Cores, 373 

Flour, 375 

Shingles, 92 

Spreader, 183 
Wooden Tanks, 318 

- Floor, 319 
Wool Felt, 32 
Workmanship, 77, 81 
Wurtzelite, 422 

Yoke, Pail Carrying, 179 

Zinc Borate Paint, 93 

Chloride, 93 

Coefficient of Expansion, 387 

Cutoffs, 134 

Roofing, 106 

Sheeting, 105 

Specific Gravity, 387 



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