ational Bureau of Standards

Library, N. W. Bidg.

AUG 1 9 1952

Physical Properties of Some

Samples of Asbestos-Cement Siding

IL

United States Department of Commerce

National Bureau of Standards

Building Materials and Structures Report 122
BUILDING MATERIALS AND STRUCTURES REPORTS

On request, the Superintendent of Documents, U. S. Government Printing OfiBce, Washington 25, D. C., will place your name on a special mailing list to receive notices of new

reports in this series as soon as they are issued. There will be no charge for receiving

such notices. An alternative method is to deposit with the Superintendent of Documents the sum of $5,

with the request that the reports be sent to you as soon as issued, and that the cost thereof be charged against your deposit. This will provide for the mailing of the publications

without delay. You will be notified when the amount of your deposit has become exhausted.

If 100 copies or more of any report are ordered at one time, a discount of 25 percent is allowed. Send all orders and remittances to the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C.

The following publications in this series are available by purchase from the

Superintendent of Documents at the prices indicated:

BMSl Research on Building Materials and Structures for Use in Low-Cost Housing * BMS2 Methods of Determining the Structural Properties of Low-Cost House Constructions., 10^ BMS3 Suitability of Fiber Insulating Lath as a Plaster Base 15^ BMS4 Accelerated Aging of Fiber Building Boards 10^ BMS5 Structural Properties of Six Masonry Wall Constructions 15(4 BMS6 Survey of Roofing Materials in the Southeastern States 15(i BMS7 Water Permeability of Masonry Walls * BMS8 Methods of Investigation of Surface Treatment for Corrosion Protection of Steel 15^ BMS9 Structural Properties of the Insulated Steel Construction Co.'s "Frameless-Steel" Constructions for Walls, Partitions, Floors, and Roofs 10^ BMSIO Structural Properties of One of the "Keystone Beam Steel Floor" Constructions

Sponsored by the H. H. Robertson Co 10^ BMSll Structural Properties of the Curren Fabrihome Corporation's "Fabrihome" Constructions for Walls and Partitions 10(6 BMS12 Structural Properties of "Steelox" Constructions for Walls, Partitions, Floors, and

Roofs Sponsored by Steel Buildings, Inc 15^ BMS13 Properties of Some Fiber Building Boards of Current Manufacture 10^ BMS14 Indentation and Recovery of Low-Cost Floor Coverings 10^ BMS15 Structural Properties of "Wheeling Long-Span Steel Floor" Construction Sponsored

by the Wheeling Corrugating Co lOji BMS16 Structural Properties of a "Tilecrete" Floor Construction Sponsored by Tiiecrete

Floors, Inc 10^ BMS17 Sound Insulation of Wall and Floor Constructions 20(i Supplement to BMS17, Sound Insulation of Wall and Floor Constructions 5jS Supplement No. 2 to BMS17, Sound Insulation of Wall and Floor Constructions 15(4 BMS18 Structural Properties of "Pre-fab" Constructions for Walls, Partitions, and Floors Sponsored by the Harnischfeger Corporation 10^ BMS19 Preparation and Revision of Building Codes t BMS20 Structural Properties of "Twachtman" Constructions for Walls and Floors Sponsored by Connecticut Pre-Cast Buildings Corporation 10^ BMS21 Structural Properties of a Concrete-Block Cavity-Wall Construction Sponsored by

the National Concrete Masonry Association 10(S BMS22 Structural Properties of "Dun-Ti-Stone" Wall Construction Sponsored by the W. E. Dunn Manufacturing Co 10(4 BMS23 Structural Properties of a Brick Cavity-Wall Construction Sponsored by the Brick

Manufacturers Association of New York, Inc 10^ BMS24 Structural Properties of a Reinforced-Brick Wall Construction and a Brick-Tile Cavity-Wall Construction Sponsored by the Structural Claj' Products Institute 15^ BMS25 Structural Properties of Conventional Wood-Frame Constructions for Walls, Partitions, Floors, and Roofs 20^ BMS26 Structural Properties of "Nelson Pre-Cast Concrete Foundation" Wall Construction

Sponsored by the Nelson Cement Stone Co., Inc 10^ BMS27 Structural Properties of "Bender Steel Home" Wall Construction Sponsored by the Bender Body Co - 10^ BMS28 Backflow Prevention in Over-Rim Water Supplies 15^ BMS29 Survey of Roofing Materials in the Northeastern States 20ji BMS30 Structural Properties of a Wood-Frame Wall Construction Sponsored by the Douglas Fir Plywood Association 15ji BMS31 Structural Properties of "Insulite" Wall and "Insulite" Partition Constructions

Sponsored by the Insulite Co 25^

•Out of print.

t Superseded by BMS116.

[List continued on cover page in]
UNITED STATES DEPARTMENT OF COMMERCE • Charles Sawyer, Secretary NATIONAL BUREAU OF STANDARDS • E. U. Condon, DirfClar

Physical Properties of Some

Samples of Asbestos-Cement Siding

Cyrus C. Fishburn

Building Materials and Structures Report 122

Issued July 6, 1951

For sale by the Superintendent of Documents, U. S. Government Printing Office, Washington 25, DC- Price 15 cents
Foreword

This report gives the physical properties of some samples of American

asbestos-cement siding and briefly discusses similar data contained in a recent

British report on the efi^ects of natural and artificial weathering of asbestoscement roofing. In this country, asbestos-cement building products have had,

in the past, a satisfactory durability record on exposure to natural weathering.

The information in this paper may be of interest and value to specification

writers and to the users of asbestos-cement siding.

E. U. Condon, Director.
CONTENTS

Page

Foreword ii I. Introduction 1 11. Siding samples 1

1. General description 1 2. Preparation and marking of specimens 2

III. Tests of the siding samples and discussion of test results 2

1> Thickness and other dimensions 3

2. Water absorption 4

3. Density and porosity 5

(a) Specific gravity 5

(b) Amount of voids 5

4. Dimensional stability 6

(a) Linear expansion on exposure to high-pressure steam 6

(b) Linear change in wetting and diying , 6

(c) Warping 8

5. Flexural strength and extensibility under fiexural load 9

(a) Strength 9

(b) Extensibihty 10

(c) Modulus of elasticity 11 IV. Tests made by the British BuUding Research Board 12

1. Laboratory measurements 12

(a) Flexure tests 12

(b) Tensile tests 12

(c) Impact tests 12

(d) Water absorption 12

(e) Moisture movement 13

2. Effects of natural weathering 13

3. Effects of accelerated weathering.. 13

(a) Wetting and drymg 13

(b) Acid ram water 14

(c) Frost action 14

V. Conclusions . , 14 ra

Physical Properties of Some Samples of

Asbestos-Cement Siding

Cyrus C. Fishburn

Measurements were made of the water absorption, weight, porosity, dimensional sta- bihty, flexural strength, and flexibility of 23 samples of American asbestos-cement siding furnished by eight manufaoturers. A report of an investigation on the weathering of British asbestos-cement roofing products was studied and is briefly reported in this paper. The modulus of elasticity of the siding samples increased with decrease in absorption.

The British investigation indicated that samples of roofing products having a high resistance

to freezing and thawing also had low absorption and high modulus of elasticity. Slight decrease In length and in moisture movement were noted with repeated cycles of wetting

and drying.

I. Introduction

The large-scale manufacture of asbestos-cement

shingles began in Europe during the 1890's through

the invention of the wet, or laminated Hatschek

process. Shortly after 1900, this process was used

and protected by patent in the United States. The

bhth of the shingle industry in the United States was coincident with the initial rise in the production of Portland cement.

In the Hatschek process, the wet solids from a mixture of cement, asbestos, and water, of thin

consistency, are picked up on a wire screen and

transferred from a cloth belt to a rotating smooth

cylinder that builds up the stock to the desired

thickness. The resulting cylindrical tube is slit, peeled from the cylinder to form a flat sheet, cut

into smaller slabs, and hydraulically pressed. In

1907, patents were issued in the United States on

a "Dry-Process" of making asbestos-cement shingles. A dry mixture of cement and asbestos is deposited on a moving conveyor, leveled, pressed,

wetted, and then consolidated by hydraulic pressure. Refinements of the two basic processes are being used today. Although asbestos-cement

shingles were developed primarily as a roofing

material, they were also used to a limited extent

as siding prior to 1932. In 1932 the first shingles

designed particularly for use as siding were manufactuz-ed, and since that time siding shingles

have been used m increasing quantities.

The physical properties of some samples of

asbestos-cement sidings were measured to obtain

information to develop methods of testing that

may be suitable for use in specifications. The

dimensions of the units were obtained, and tests were made of their water absorption, density, and

porosity, dimensional stability, and flexural strength. The agreement of the results of the

measurements made on dift'erent specimens cut from one shingle was used to obtain an estimate of

the precision of some of the test methods.

Some of the data and conclusions obtained from

a British investigation on cement-asbestos roofing

materials ' are also presented in this paper. The

physical properties of the United States and

British products were compared in those cases where similar .data were obtained.

I Building Research Technical Paper 29, Weathering Tests on Asbestos- Cement Roofing Materials, Department of Scientiflo and Industrial Research, Park House 24, Rutland Gate, South Kensington, London S. W. 7, Eng.

II. Siding Samples

1. General Description

Twenty-two samples of shingle siding and one

sample of clapboard siding were furnished to the

Bureau by eight manufacturers of asbestoscement building products. Little or no information was obtained from the manufacturers regarding the methods of making the samples and the

kinds and proportions of the materials used in

them. Twenty of the 23 samples were woodgrained, 19 were either white or gray in color, and

4 contained pigments or aggregates of colors other

than white or gray. Some samples were slightly

water repellent and the units in one sample were

highly water repellent on both faces. The ex- posure face of the units in one sample were treated

1
with a white pigmented organic coating. It is probable that some of the samples were subjected

to high-pressure steam curing at the place of

manufacture.

Each sample is identified in this report by a number, the sample numbers running consecutively in the order that the samples were received

at the Bureau. Samples 4 and 4x of similar units, were made at the same plant but were received at

different times.

2. Preparation and Marking of Specimens

The units in each siding sample were numbered

as selected for test, and specimens cut from the

units, were marked with the sample number and

III. Tests of the Siding Sampl

Tests were made on like groups of specimens

cut from all the samples. Only in table 1, which

lists the dimensions, are the data presented in

full, for all samples. In tables 2 to 15, inclusive,

the data are given only for the samples representing the maximum, the minimum, and the

normal, or an intermediate, value of the property

or function under consideration. The selection

of the normal, or intermediate, sample was an

arbitrary one, based on no fixed rule. The precision of a method depends upon the

degree of consistency among repeated measurements. This is usually weighed either in terms

of the standard deviation or in terms of the

coefficient of variation. The coefficient of variation may be defined as the ratio of the standard

deviation to the average or arithmetic mean.

Where, as in this investigation, the number of

measurements on a shingle unit or the number

of specimens cut from a shingle is limited, it is desirable to combine the information obtained

from several shingles. This combination is done

by the technique described in H. A. Freeman's

Industrial statistics, formula 1, p. 58. The

formula gives the standard deviation or precision

of an individual measurement about its mean for a shingle. The precision of a test procedure, or

test method is l/^J 7i times the precision determined from equation 1 ; the symbol n represents

tne unit number. "Wlien the direction of the

principal axis of a specimen with relation to the

vertical or horizontal dimension of the unit, as used on the wall, was of importance, the direction was indicated by A or B on the specimen. The

long axis of the A specimen was parallel to the

verticle dimension of the unit as used on the wall. The long axis of the B specimen was parallel to the

horizontal dimension of the unit. The grain ran

parallel to the A direction in specimens cut from

units whose faces simulated a wood grain. A and

B are used through the remainder of the text without further definition.

Specimens were cut to the proper size and shape

with a }^-in. -thick silicon-carbide cut-off wheel. A

diamond saw was used to trim the ends of some

specimens.

J and Discussion of Test Results

the number of determinations per shiagie. The

lower the value for the precision as determined

above, the better the agreement among the

measurements.

The variability among different shingles, taken

at random and representing a sample, may be

determined by computing the standard deviation

of the shingle averages about the grand average,

as in formula 2, p. 59 of Industrial statistics. A

judgment of the adequacy of a test method may

be made by comparing the precision of the test method with the variability of the shingles. The

variability of shingle averages and the precision

of the test method are given m this paper for measurements of shingle thicloiess by three

difl"erent methods and for the water absorption of

the shingles. The variability of shingle averages,

alone, are given for other data. Throughout the

paper, the coefficient of variation is used instead

of the standard deviation.

It should be understood that error in measure- ment in the tests is mclucled in the variability of

the shingles. The variability among shingle

averages listed in the paper are not corrected ^ for the precision of the test method.

- The corrected variability of tlie shingle average would be V (variability of shingle average)^— (precision of test metllod)^.
Table 1. Dimensions " of siding shingles and clapboards.

Sample Width, W

Height, H Thickness ^ Number of nail holes

Diameter of nail holes

Average dis- tance of nail holes from

top edge

Average dis- tance of nail holes from

side of shingles

Lap

Gross

area

max min ma.\ min Average ' Top

holes

Bot- tom

holes Top

holes

Bot- tom

holes Top

holes

Bot- tom

holes max min

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

12

3

4 i 4x d

56

78

9 e

10

1112

1314

1516

17

18

19

20

2122

23

in. 23. 99

24. 00

23. 99

24. 00

23. 99

27. 01

26. 90

23. 99 23.98

96. 02

23. 96

24. 00

24. 00 24.00

23. 99

23. 99

23. 99

23. 98

24. 00

24. 04

24. 00

24. 01 24.03 23.98

in. 12.00 12.02

12.02

12. 01 12.00

12.01 12.00

12.00

12.00

9. 50

12.01

12. 04

12. 00 12.00

12.00

12.00

11.76

11.76

12.01 12.03

12.01 12.02 12.02

12.02

in. 11.76

11.80

11.81 11.75 11.72

11. 63 11.60 11.78 11.78

9. 48

11.84 11.86

12. 00 12.00

11.70

11.70

11.45 11.46

11. 75

11.77

11.75

11. 76 11.77 11.75

in.

0. 163

. 166

. 159

. 158 .149

.159

. 154

. 194 .195

. 196

.170

. 169

. 134

. 139 .152

.167

.161 .179 .150

.154

.159

.151 .155 .156

in.

0. 148

. 143

. 143

. 134 .123

.136

.130

.181

. 185

. 196

. 152 .150

. 134 .139

. 137

. 149

. 145 .165

. 130 .125

. 141 .136

. 131 .131

in.

0. 15 .17 .16

. 14 .14

. 15

. 14 .18

. 19

. 19

. 15 .16

. 13

. 14

. 15

. 16 .15

.17

. 14

. 15

.15

. 14

. 15 .15

in.66

6

5

5

6

6

5

514

66

5

56

6

6

6

5

5

55

5

5

-

in.

0. 11

. 10

. 11 .11 .10

.10 .09

.10

.10

. 11

.10

.11

. 10

. 11

. 11

.11

. 12

. 12 .10

.10

.10

.10

.10

.10

in.

0. 16 .15

.16

.15

.15

. 15

. 15

. 15

. 15

. 15

.13

. 14

. 14

. 15

. 15

. 15 .12

. 11

. 16

.15

.16

.16

. 14

. 15

in.

0. 74 .76 .84

.83 .82

. 75

. 77 .82

.82

1.02

0.77

.77

. 76 .79

.75

.75 1.07

1.08

0. 77

.77

.77 .76

.77 .82

in.

10. 49

10. 49

10. 44

10. 49

10.49

10. 44

10. 42

10. 46

10.46

7. 95

10.46

10. 48

10. 42

10. 46

10. 67

10.66

10. 42

10. 43

10. 46

10. 47

10.46

10. 47

10. 48

10. 46

in. 1.01

1.01 1.39 3.02

3.02

1.02

1.00 2.98

2.99

0. 57

.98

.99

3. 02

3.04

1. 50

1.50

1.50

1. 50

3, 02

3. 02

.3. 00

3.01

3. 02

3.01

in. 1.38

1.55 1,38

1.40

1.40

2.02

2. 00

1.39 1.38

0. 57

1.99

2.00

1.40

1.38

1.50

1.50 1.62

1.52

1.49

1.53

1.50

1.50

1.61 1.39

in. 1.48

1.47

1.53

1.44 1.45

1.52 1.54

1. 50 1.51 1.55

1.51 1.50

1.53

1. 51 1.29

1.28

1.28

1.28

1.50

1.50

1.28

1.50

1.47

1.52

in. 1.21 1.25

1.31 1.20

1.20

1. 14 1.15

1.27 1.27

1.50

1.33

1.30

1.52

1.45

0. 98

.99

.97

.98

1. 24

1. 26

1.24

1.25

1.25 1.23

ft'

1.98

1.98

1.93

1.93

1.93

2.21

2.21

1.98

1.98

6. 33

1.98

1.99 2.00

2.00

1.97

1. 97

1.95

1.95

1.98

1. 98

1.98

1.98

1.98

1. 98

" Unless otherwise noted, the values are an average of measurements on 10 shLugle imits and' 3 clapboard units. The values are an average of 9 observations on each of 5 shingle units and of 14 observations on each of 5 clapboard units.

« Average values observed by a water displacement method on a different gi'oup of specimens,

d Samples 4 and 4x were two different shipments of similar units.

= Sample of clapboards.

1. Thickness and other dimensions

The thickness of the samples was measured by

three different methods

:

Method 1. The thicknesses of five whole units

taken at random from each sample were measured

with a micrometer dial reading to 0.001 in. for each

division of the dial. The plunger on the dial was

fitted with a sharp point, and the dial was mounted

in a vertical position on a metal base. A ball bearing was fixed in the base directly below the

dial plunger, and the projecting top of the bearing was machined to a horizontal surface having a diameter of 0.1 in. The units were moved over

the bearing with their faces upward, and both the

maximum and the minimum thicknesses of the

units were measured at each of nine places on each

shingle unit, and at 14 places on each clapboard

unit. The places where the measurements were made were spaced symmetrically about the units

so that a general average of the maximum and

minimum thicknesses could be obtained. The

thicknesses obtained by this method are listed in columns 5 and 6 of table 1. Method 2. The maximum thickness of each sample was measured in a manner similar to one once proposed for use in Federal specifications. Twenty

A and 20 B specimens 6 by 12 in. in size w^ere cut from different units taken from each shingle sample. They were placed, one at a time, between

steel plates % by 6 by 12 in. with polished parallel

faces. The over-all thickness of the plates and

specimen was measured with a micrometer caliper.

Four observations were made on each specimen,

the micrometer caliper being placed at the midpoint of each side and near the edges of the plates.

The average maximum thickness of the samples

obtained in this manner is listed for samples 6, 12, and 16 in column 2 of table 2. The differences

between the maximum thicknesses of the samples

obtained bv methods 1 and 2 are listed in column

3 of table 2.

3
Table 2. Comparison of maximum thickness obtained by methods 2 and 1

Sample

Average maximum

thickness determined by

method 2 "

Apparent differ- ence in maximum

thickness measured by

methods 1 and

2 b

Inch Inch

6 (max) 0. 241 0.087

12 (mill) .150 .016

16 (normal). . .189 .028

» Specimens placed between steel plates and their maximum thickness measured with a micrometer caliper. The thicknesses obtained by method 1, listed in column 5 of table 1, are subtracted from the thickness obtained by method 2. Method 3. The average thickness of the samples was also measured by a water-displacement

method. Ten or more 4- by 9-in. specimens M^ere cut from five or more units taken from each sample.

These units were not the same as those selected

for the maximum and minimum thickness measurements. The specimens, fully saturated, were weighed when suspended in water and when in aii-. The average thicknesses obtained in this manner

are listed in column 7 of table I. The most precise method of measuring the maximum thickness of the samples was method 1, in in which a micrometer dial was used. As the precision of the measurements depended directly upon

the number of observations, the method was some- what tedious. The coefficients of variation for the

variability of the shingle averages and for the precision of test method 1, are listed below for samples

6, 12, and 16.

Sample

Variability

of shingle averages »

Precision of

test method i>

pfmax thickness. 2.7 4.9

1.4

9.9

11.3

1.0

1.2 0.8

1.7 1.7

\min thickness. ______ _.. 12 0 __ jc/max thickness. \min thickness

" Based on the variability among 5 shingle averages.

•> Based on the variability of 9 determinations per shingle, combined over

5 shingles. " Shingles of sample 12 were smooth-faced. Any curvature of the specimens introduced a

positive error in the measurements of thickness by

the use of steel plates, method 2. The coefficients

of variation for the variability of the shingle

averages and for the precision of test method 2, are listed below.

Sample

Variability

of shingle averages «

Precision of

test method >>

7.7 4.9

1.9 7.7

S.3

2.6

1.9

1.0

1.8

1.7

«{!::::::

12, A and B » Ki:::::::::::;::

« Based on the variability among 20 shingle averages.

>> Based on the variability of 4 determinations per shingle, combined over

6 shingles. " Shingles of sample 12 were smooth-faced.

The precision of the test method for maximum

shingle thickness obtained by methods 1 and 2 indicates, for samples 6 and 12, that method 1 was slightly more precise than method 2. Actually, there was a great difference in the maximum

thickness of the samples, as measured by the two

methods. From table 2 it is clear that method 2

is higlily inaccurate. An analysis of the data obtained from all samples indicates that the average

positive difference, bias, in thickness between the

values obtained by methods 1 and 2 was about 16

percent of the average by method 1. For sample

6 the difference was over 50 percent. The method

of calculating the precision of the test method does

not, of course, include the effects of constant

errors inherent to a method of measurement.

Another important factor regarding method 2 was

the difficulty at making steel plates with parallel

faces. The plates used in this investigation had a thickness tolerance of ±0.0005 in., and it was found

necessary to select plates having a thickness of

K in. or more before grinding and polishing their

surfaces.

The measurement of average thickness of the

samples by water displacement, method 3, was a simple operation, giving accurate and reproducible results. The coefficients of variation for the

variability of the shingle averages and for the

precision of test method 3, are listed below for samples 6, 12, and 16.

Sample

Variability

of shingle averages "

Precision of

test method

6 5.

1

b 1.8

12 1.9 » 0.5

16 . 8.2 <i.7

» Based on the variability among the different groups of shingle averages. ;'

•> Based on the variability of 14 determinations combined over 6 shingles. i « Based on the variability of 18 determinations combined over 5 shingles.

'

<i Based on the variability of 14 determinations combined over 5 shingles.

Except where the minimum thickness is required

to calculate the modulus of rupture, the maximum

and the minimum thickness of a wood-grained unit

are of little practical interest. The average thickness, determined by method 3, appears to be a more practicable requirement of specification purposes than the maximum thicknesses determined

by either method 1 or 2. Excepting the large and constant errors inherent

in method 2, because of the warping of the specij mens, the precision of all test methods is sufficient

in the light of the variability of the material i tested

.

2. Water Absorption

The water absorption of the samples was determined from tests of 4- by 9-in. specimens cut from

five shingles or clapboard units taken from each

sample. The specimens were dried to constant * weight in an oven at 221° to 239° F (105° to 115° '

4
C). After cooling, they were immersed in water

at 70° F (21° C) for periods of 1, 3, 5, 15 min,

1 hr, 1 day, 3 days, and 7 days. The absorptions

during each of these immersion periods are listed

in table 3 for samples 2, 10, and 12.

Table 3. Water absorption »

Sample

Immersion period

2 12 10 (max) (min) (normal) % % %

1 min - .3.8 0.6 3.1

3 min . . . . 7.6 .8 4.6

5 min. 15.4 1.2 ' 5.0 15 min... 21.4 1.8 7.4

1 hr 25.5 3.7 11.8

1 day 27.0 10.4 15.0

3 days 27.7 10.8 1.5. 5 27.9 11,0 16.

1

• Observed on groups of 5 to 18 specimens cut from 5 different shingles.

The average absorption for all samples during a 7-day immersion period was 16.2 percent, by dry

weight. The maximum absorption was 27.9 per- cent (sample 2) and the minimum absorption was

11.0 percent (sample 12). For all samples, the

absorption during immersion periods of 1 min,

1 hr, and 1 day were, respectively, 18, 65, and

93 percent of the absorption during a 7-day immersion period. A study of the data for all samples indicates that samples having waterrepellant faces or backs had greater than average

absorptions during immersion periods of 1 hr or

less. It follows that, for the initial periods of

immersion, most of the water absorbed by the 4- by 9-in. specimens pentrated the cut edges of the

specimens. The coefficients of variation for the

variability of the shingle averages and the precision

of the test method for absorption during a 7-day

immersion period are listed below for samples

2, 10, and 12.

Sample

Variability

of shingle averages »

Precision of

test method

2 i) 8.8

12 .5.6 2.8

10 3.3 d 0.9

» Based on the variability among 5 shingle averages.

^ Only 1 determination on each of 5 shingles.

' Based on the variability of 18 determinations combined over 5 shingles,

i Based on the variability of 15 determinations combined over 5 shingles.

The same specimens, sample 12, were used both

in the absorption and in the average thickness

measurements. An examination of the coefficient

of variation data indicates, for this sample, that

the variability of the shingles was greater and

the agreement among the measurements (precision

of test methods) was less for the absorption than

for the average thickness.

3. Density and Porosity

The specific gravity and the pei'cenlage of voids were determined on groups of 5 to 18 specimens,

4 by 9 in., cut from 5 shingle or clapboard units

taken from each sample.

(a) Specific Gravity

The specimens were dried in an oven at 221°

to 239° F (105° to 115° C). Volume determinations were made with a gas-expansion volumenometer.^ The specific gravities of samples 15,

13, and 10 are listed in table 4. Table 4. Specific gravity

Sample Number of Specific specimens gravity

15 (max) 13 2. 64

13 (min) 18 2. 41 10 (normal) 15 2. 50

(b) Amount of Voids

The specimens previously used to determine the

specific gravitv of the samples were immersed in

water at 70° F (21° C) for 7 days, and the gross volume of the saturated specimens was calculated

from their difference in weight when supported

in water and in air. The volume of the voids was

found by two methods. In method 1 the voids were determined by comparing the gross volume,

obtained as stated above, with the solid volume

determined by means of the gas-expansion volumenometer. In method 2 the voids were

obtained by comparing the gross volume with

the volume of water absorbed during the 7-day

immersion period. The volume of the voids, as found by methods 1 and 2, is listed in table 5 in percentage of the gross volume of samples 2, 12, and 10. The specific gravity of the samples ranged between 2.39 and 2.64, and the average value for all samples was 2.48. With few exceptions, those

having a high specific gravity also had a low water

absorption. Sample 12 was one of the exceptions,

having a specific gravity of 2.45 and a minimum

water absorption.

As determined by method 2, the volumes of the

voids ranging between 22 and 43 percent of the

gross volume, averaged 30-percent, and were

about 5 percent higher than the volumes determined by method 1, see table 5. The observed

amount of absorbed water was used in determining the voids by method 2, and the absorption of the samples was almost directly proportional to the amount of voids. The solid volumes of the

specimens and their absorptions during the 7-day

water immersion were not redetermined after

the initial drying and wetting. Some changes

in the ph3'sical properties of the specimens ma}^

'Joseph C. Richmond, John B. Peterson, and Winslow H. Herschel, An

improved volumenometer, J. Am. Ceram. Soc. 26, No. 4 (April 1943).

932016—51 2 5
have occurred as a result of the exposure to drying and wetting, but it is not known how much

such changes, if any, affected the amount of voids.

Table 5. Volume of the voids *

Table 6. Linear expansion on exposure to high-pressure steam »

Volume « determined Sample Number of by—

specimens Method 1 b Method 2 0

2 (max).._ % %

.5 38 43

12 (min) 18 15 22

10 (normal)- __ ._ 15 26 29

» Volume in percentage of the gross volume of the specimens.

•> Ratio of the solid volume, as determined by means of a gas-expansion volumenometer, to the gross volume.

« Ratio of the volume of absorbed water to the gross volume.

4. Dimensional Stability

(a) Linear Expansion On Exposure To High-Pressure

Steam

A measure of the dimensional stability of the

siding shingles was obtained by observing the

linear expansion of specimens exposed to highpressure, steam. The specimens were 2 in. wide

and 10 in. long. A pair of specimens, one A and

one B, was cut from each of five diflferent units

taken from each shingle sample. The definition

of the A and B specimens is given in section II of

this paper.

Changes in length of the specimens were observed with a horizontal dial-micrometer comparator. The comparator, figure 1, consisted of a heavy frame supporting a movable table between

two brackets. A micrometer dial supported by

one of the brackets was used as a zero indicator.

The other bracket supported a 50-tlu-ead/in.

micrometer screw giving a vernier reading of

0.0001 in. The table was fitted with two vertical

lifts and crossarms on which the specimens rested. The positions on the brackets of the micrometer

dial and screw could be adjusted to fit a range in

specimen length from about 8 to 24 in. Brasscoated drive screws inserted in the ends and on

the longitudinal axis of the specimens provided

suitable bearing surfaces between the specimens

and the comparator. A flat steel plate of a size and shape similar to those of the specimens was

used as a standard bar for the comparator measurements.

The specimens were immersed in water at 70° F

(21° C) for 2 days. After removing them from

the water, excess surface water was wiped off with a damp cloth, and the initial comparator

observations were made. Wliile still damp, the

specimens were placed in an autoclave and were

subjected to steam at a pressure of 295 psi for 3 hr, as prescribed in Federal Specification SS-C-158b,

Section F-63d (9). The specimens were then

removed from the autoclave, cooled to 70° F

(21° C) by immersion in water, and their lengths were determined with the comparator.

Sample

Linear expansion

Direction A>> Direction B <= Average of A and B

6 (max).

Percent

0. 051

•i -.001

.030

.027

Percent

0. 065

.003 .019

.027

Percent

0. 058

.001 .025

.027

8 (min)

3 (normal) «. 23 (normal) '

» 3-hour exposure to steam at 295 lb/in.' Measured in a direction parallel to the vertical dimension of the shingles

as used on the wall. Average for 5 shingles.

» Measured in a direction parallel to the horizontal dimension of the shingle

as used on the wall. Average for 5 shingles.

d The minus sign indicates a shrinkage.

e A normal sampli- in which the expansion in one direction was significantly greater than that in the (it her direction.

' A normal samjile in which the expansion was about equal in both the A

and the B directions. The greatest linear expansion of specimens subjected to high-pressure steam was the 0.065 per- cent observed in the B specimens cut from sample

6, see table 6. The A specimens from two samples, 8 and 7, showed little or no expansion as a

result of this exposure. The average expansion

for all samples was 0.024 percent in the A direction

and 0.023 percent in the B direction. The coeffi- cients of variation for the expansions are listed below for samples 6, 8, 3, and 23.

Sample

6 (max)|^

8 (min)[^

3 (normal)

23 normal)

Variability

of shingle average a

14

14 340

300

3

» Average for one A and one B specimen cut from each of 5 shingles,

b The expansion in the A direction was 50 percent higher than that in the B direction. The linear changes noted for sample 8 were about equal to the limits of sensitivity for the

observations and are barely significant. The high

value for the coefficient of variation reflects this condition. In general, the expansion of the samples may have been dependent upon the incidence

of steam curing of the units. There was little or no correlation between the absorption of the samples and the linear expansion on exposure to steam.

(b) Linear Change in Wetting and Drying

The linear changes resulting from the alternate

wetting and drying of small specimens cut from

the siding units were measured on the comparator

(fig. 1) previously described. The specimens were

2 in. wide; those cut from the shingle units were

10 in. long, and those from the clapboard units

(sample 9) were 9 in. long. Each sample was

6
The following procedure was used in testing

samples 3 to 23. Specimens were placed in water

at about 70° F (21° C) for 2 days, removed from

the water one at a time, wiped witli a damp cloth,

and initial observations made at once in the

comparator. While still wet, the specimens were

placed in an oven at 122° F (50° C) for 2 days.

On removal from the oven, and while still warm,

they were placed in a desiccator containing

potassium acetate. The air in the desiccator was

at a temperature of about 70° F (21° C) and a

relative humidity of about 20 percent. As indicated in table 7, the specimens usually remained

in the desiccator for 1 day before comparator

observations were made. Immediately after their

removal from the desiccator, the specimens were

again placed in water, completing the first cycle.

The specimens were subjected to foiu* or five cycles.

The specimens representing samples 1 and 2 were

subjected to more cycles and to periods of wetting

and drying that were of longer duration. The

changes in length during these wettjng and drying

tests are listed in table 7 for samples 14, 12, and 11,

and are based on the initial comparator observations.

Table 7. Moisture movement and length change of siding samples on wetting and drying *

Sample

1

Cycle

Water storage Oven storage Desiccator stor- age Moisture movement Length change "

Duration Temp Duration

Relative humidity

Duration Temp Change in condition A d B ' Average Condition A <! B ' Average

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

14 (max)

12 (min)

11 (nor- mal)

1

2

3

4

/ 1

J ^

1 ^

I 4

1

2

3

4

5

Days

{ :

{

{

> 2

t 2

{ :

{

( :

{ :

{

^ 2

° F

71

71

69

69

71

71

71

4

1

d

70

68

70

69

71

Days

2

2

2

2

2

2

2

2

2

2

2

2

2

Percent

16

15

14

15

16

15

14

15

16

17

15

18

17

Days 0 p

71

71

69

71

71

71

69

71

71

72

71

72

71

Wet to dry

Dry to wet Wet to dry

Dry to wet Wet to dry

Dry to wet Wet to dry

Dry to wet

Wet to dry

Dry to wet Wet to dry Dry to wet Wet to dry

Dry to wet Wet to dry

Dry to wet

Wet to dry

Dry to wet Wet to dry

Dry to wet Wet to dry

Dry to wet Wet to dry

Dry to wet Wet to dry

Dry to wet

Percent -0. 144 +. 122

134 +. 124 -. 126 +.119

-.116

+. 112

-.061 +. 060 -.065 +. 064 -.063 +.062

-.062 +.062

-.098

+. 091 -.090 +. 090 -.097 +.092

-.086 +.085

-.096 +.096

Percent -0. 141 +. 124 -.134 +. 125 -. 126 +. 117 -.118 +.113

-.060 +.059

-.065

+. 064 -.063

+. 061 -.061 +. 061

-.092

+. 084 -.084 +. 083 -.089

+. 086 -.082 +. 081 -.087

+. 085

Percent -0. 143 +. 123 -. 134 +. 125 -. 126 +. 118 -. 117 +. 112

-.060

+. 060 -.065 +.064

-. 063 +. 061 -.061 +. 061

-.095 +.088

-.087 +.087

-.093 +.089

-.084 +.083

-.091 +. 091

Wet

Dry Wet

Dry Wet

Dry Wet

Wet

Dry

Wet

Dry Wet

Dry Wet

Wet

Dry Wet

Dry Wet

Dry Wet

Dry Wet

Percent

-0. 022 -.012

-.032

-.014

-.040 -.012

-.044

-.001 -.004

-.001 -.004

-.003

-. 003 -. 003

-.007

+.001 -.008

-.006

-.013

0-.013

-.011 -.013

Percent -0. 016 -.010

-.026

-.011

-. 034 -.012 -.038

0-.005

-.001 -.004

-.003 -.004

-.003

-.008

0-.009

-.006

-.012

0-.011 -.006

-.013

Percent

-0. 019 -.011 -.029

-.012

-. 037 -.012

-.041

-.001 -.005

-.001 -.004

-.003

-.004

-.003

-.008

0-.008 -.006

-.012

0-.012

-.008

-.013

a The cyclical wetting and drying exposure given the specimens was usually as follows: Two days in water at 70° F, 2 days in an oven at 122° F (50° F) and

1 day in a dessicator at 70° F. The linear change produced by a change in moisture content from the wet to the dry and from the dry to the wet condition.

» The cumulative length change when in the wet or in the dry condition, based on the original lengths for the initial wet and for the initial dry condition. The long axis of A specimens was parallel to the vertical dimension of the unit as used on the wall.

" The long axis of B specimens was parallel to the horizontal dimension of the unit as used on the wall.

Figure 1. The comparator. A flat plate instead of the round bar was used as a standard bar.

represented by 10 specimens, 5 A specimens and

5 B specimens. With but few exceptions, only

one pair of specimehs, A and B, were cut from a

single unit. Stainless-steel drive screws, size 00

by /i6 in., were inserted in the ends of the speci- mens in the longitudinal axis and provided suitable

noncorrosive contacts between the ends of the

specimens and the comparator used to measure

the changes in length.

7
Wlien stored in water, in the oven, and in the

desiccator, the specimens were racked about % in. apart, with their long axes horizontal. When in the oven the long axes were parallel to the direction of air flow. The heated air passed over trays

of calcium chloride before meeting the specimens.

Although the oven was operated with all doors

and vents closed, it was noted that the relative

humidity of the air in it fluctuated with changes

in the relative humidity of the outside air. The time interval required to make comparator

observations in duplicate was short, and it was

noted that the specimens tended to decrease

slightly in length (about 0.0001 in.) after removal

from the water and to increase slightly in length

after removal from the desiccator.

In this paper the moisture movement is defined

as the linear change pi'oduced by a change in

moisture content from the wet to the dry and

from the dry to the wet condition. The length

changes are defined as the cumulative changes

in length of the specimen when wet and when dry,

based on the original length for the initial wet

and the initial oven-dry conditions, respectively.

The cyclical moisture movements and length

changes that were produced by wetting and drying were much more affected by slight changes in the

relative humidity of the air in the drying oven

than by changes in the temperature of the air and

water. The moisture content of the wet specimens was usually about the same for each cycle, and the

data obtained from measurements of the speci- mens when wet were more consistent than those

obtained from them when dry. The length

changes when either dry or wet, listed in column

14, 15, and 16 of table 7 were dependent upon

the relative dryness (or wetness) of the specimens on the initial and all later cycles of wetting and

drying. The data showed that the moisture

movement and the lengths of the samples tended

to become progressively smaller with continued

wetting and drying.

The coefficients of variation for the moisture

movement of samples 14, 12, and 11 are listed below. The listed coefficients are the average

of the coefficients for length change produced by

changes in moisture content during the 8 to 10

half-cycles, wet to dry and dry to wet, that are

listed in table 7.

Variability Sample of shingle average "

14 (max)

12 (min) {^--;

11 (normal)

> The average of a group of 8 to 10 coefficient determinations, each represent- ing an average for a group of 5 shingles.

(c) Warping

The warping, or change in curvature, of the

siding samples was observed in specimens 6 in. wide and 11 in. long. Each sample was rep- resented by four specimens, two of A and two

of B. One A and one B specimen was cut from

each of two units.

Curvature of the specimens was observed after an initial drying, after wetting and after a second

drying. Each drying consisted of storage for 2 days in an oven at 122° F (50° C) and 2 days in a

desiccator containing potassium acetate at about

80° F (27° C). The relative humidity of the air in the oven at the time the specimens were re- moved was about 33 percent. The wetting ex- posure consisted of immersion in water at about

73° F (23° C) for 2 days.

The specimens were supported in a horizontal

position on a device, figure 2, and is described in detail in the following section. A micrometer dial placed under the center of each specimen was used

to measure the curvature. One end of the specimen was placed in contact with a positioning

frame, not shown in figure 2.

/

Figure 2. Load support for flexural tests. Each measurement consisted of two observations. One observation was made with exposed

(outer) face of the specimen up and the other with

the exposed face down. The difference between

the two dial readings was halved to obtain the

deflection at the center of the specimen. The

curvature of the specimens is defined as the reciprocal of the average radius of curvature in inches,

which was calculated from the deflection. The

curvature and the warping or change in curvature

produced by wetting and drying the specimens are

listed in table 8, for specimens 17 (max), 2 (min),

and 4 (noi'mal). A positive value for the curvature indicated that the exposed face of the specimen was convex, curved outward.
Table 8. Warping of ndinq samples "

Curvature t Change in curvature—>>

Sample After initial drying After wetting After final drying On wetting From initial to

final drying A B .4 B A B A B A B

17

2

4

Inch-'

«-f0.0004

-I-.0006 -.0009

Inch-' '-0.0004 "-.0002 -.0003Inch-' +0. 0030 =+.0000 -.0017Inch-'

"-1-0.0018 «-.0002 -.0014

Inch-' =4-0.0004 =+. 0006 -.0010Inch-' "-0.0001 "-.0002 -.0005

Inch-' +0. 0026 +0

-.0008

Inch-' +0. 0022

0-.0011

Inch-'

0

0-.0001

Inch-'

-f0,0003

0-.0002

» Each value represents the average obtained from tests on 2 specimens of A, and on 2 of B. The long axes of the A specimens were parallel to the vertical dimension of the unit, as used on the wall. The long axes of the B specimens were normal to this dimension.

i> The curvature is the reciprocal of the radius of curvature, in inches. A positive value of curv.iture indicates that the exposed face of the unit was convex.

« The face of 1 of the 2 specimens was convex, that of the other specimen was concave. The values are the algebraic mean of the curvatures.

The greatest change in curvature occurred on

wetting the specimens from the dry condition.

Most of the specimens tended to regain their

original shape on the final dr^ying, after wetting.

Specimens from sample 2 did not warp on wetting

and drying for both the A and the B specimens.

A specimens, cut from samples 5, 7, 10, and 19,

warped in a different direction than did the B

specimens.

5. Flexural Strength and Extensibility Under

Flexural Load

The strength and extensibility in flexure of the

siding samples were determined from tests on

specimens 6 in. wide and about 11 in. long. Each

sample was represented by at least 40 specimens

divided into 8 groups of 5 or more specimens each.

At least five different units were used in making

the specimens for each group. Four of the eight

groups contained A specimens only and 4 contained B specimens. Other variables between the

groups were the positions of the exposed face of the specimens on the loading support, face up or

face down, and the moisture content of the speci- mens at the time of test. Specimens in the dry

condition were dried in an oven at 221° to 239° F

(105° to 115° C) for 1 day and were cooled to room

temperature in a desiccator before being tested. Wet specimens were immersed in water at room

temperature for 1 day before being tested. The loading support for the specimens is illus- trated in figure 2. The specimens were supported on }2-in. round steel bars spaced 10 in. apart, center to center. The ends of the bars were in- serted in and supported by ball bearings, which

permitted the bars to rotate. The supporting

base under one bar was rounded, permitting the

bar and its support to rock slightly in a vertical

plane normal to the span. The radius of curvature of the base was equal to the height of the top

of the bar above the base. A micrometer dial

reading to 0.001 in. was fastened to the loading

plane, and was in contact with the bottom of the

specimen at midspan. The flat, circular top of

the dial plunger in contact with the bottom of the

specimen had a diameter of yi in. A 1-in. -diameter aluminum tube was fastened to the head of the testing machine, and load was

applied to the specimens on a line at the center of

the span. The load was applied continuously to the specimens at the rate of 20 Ib/min until failure

occurred. Deflection observations were made at zero load and at each load increment of 2 lb. Failure of the specimens was not sufficiently

abrupt to damage the micrometer dial. The

specimens were tested on a Southwark hydraulic

testing machine equipped with a dial having a

load range of 0 to 240 lb. The maximum loads

are listed in table 9 for samples 8,2, and 13. The

loads were corrected for a nominal specimen width

of 6 in.

Table 9. Corrected maximum flexure loads ^

Condition Specimen Face

Sample

8 (max)2 (min)

13 (nor- mal)

Dry b

Wet c

[Up \Down

lUp

\Down-. . .. fUp

IDown.- _. rup

\Down..

lb <i65.8 66.7

<i57. 4 51.9

45.5

46.9 35.2

''34.9

lb 25.2

25.9 33.4

30.4

22.0

20.5 31.6

26.1

lb 39.9

38.1 37.7

37.0

25.2

24.3

23.9 121.3

Coefficient of variation ». _ 10 10 8

» Average maximum load for 5 specimens, 1 specimen from each of 5 shingles, unless otherwise noted. The specimens were 6 in. wide and were loaded on

a line at the center of a 10-in. span. The loads are corrected for a nominal

G-in. width.

t> Dried in an oven at 105° to 115° C for 1 day.

< Immersed in water at room temperature for 1 day.

<< Average for 10 shingle specimens. A second parcel of 5 was tested when

the dispersion of the loads on the initial group was high,

e Average coefficient for the 8 groups of specimens.

(a) Strength

Strength of the wet specimens was approximately 70 percent of that of the dry specimens.

Specimen groups from some samples were con9
sistently stronger when the dhection of bending was parallel to either the vertical or the horizontal

dimension of the units {A or B specimens).

Again, in some cases, the specimen groups for some samples were consistently stronger when the

specimens were tested either with the face up or down. However, the effect of moisture content on the strength of the specimens was the only

consistent relation applying to all samples.

The coefficients of variation for the loads on

groups of like specimens were calculated for all samples but are listed in table 9 for only samples

8, 2, and 13. The coefficients, averaged for all sample groups, were not consistently higher or lower for any particular group, such as specimen

A or B, tested when dry or wet or face up or down.

It is likely that the flexural strengths of some B si^ecimens that were cut from some units with

simulated wood grain were somewhat reduced by

the graining. Significant and consistent differ- ences between the strengths of A and B specimens

cut from the same sample probably resulted from

an orientation of the asbestos fibers in one dhection or another. For samples 1, 2, 3, 10, and 11,

the groups of B specimens were 25 percent or more

stronger than were similar groups of the A speci- mens. For samples 5, 6, and 7, groups of the

A specimens were markedly stronger than were

similar groups of the B specimens. From an ex- amination of the data obtained from wetting and

drying all samples, it was noted that for samples

1, 2, 3, 10, and 11, the moisture movement for the

B specimens was less than that for the A specimens

and for samples 5, 6, and 7, the moisture move- ment for the A specimens was less than that observed for the B specimens. Further data on this matter are found in table 6 for sample 3. The

average linear expansion of the 3, A, specimens was 50 percent greater than that of the 3, B,

specimens. These observations on the effects of

fiber orientation on flexural strength and on

moisture movement correlate those previously

found and discussed in the excellent British Technical Paper 29. (See footnote 1, p. 1.) The average modulus of rupture is listed in table 10 for samples 12, 2, and 3. As the thick- ness at the line of break of the specimens was not

measured, the values are only approximate. The

thickness used in the calculations was measured

as described for method 1 (section III-l) and was

equal to the average minimum thickness of five units taken at random from each sample. These

thicknesses are listed in table 1.

Table 10. Modulus of rupture

Condition

Dry.

Wet.

Specimen Face

\DownfUp...., \Do\vn- Up„...

Down_.

/Up..._. \Down..

Coefficient of variation

Sample

12 (max)

t 5, 600

5, 300

5, 300

b 5, 100

3, 700 3,700

3, 500

b 3, 300

2 (min)

Ib/in.^ 2,200

2, 300

2, 900

2, 600

1,900

1,800

2, 700 2,300

3 (normal)

3, 100

3, 000 3,900

4, 100 2,000

2, 300

2, 300

2,600

• » Average for 5 specimens, 1 from each of 5 shingles, unless otherwise

noted.

"t" Average for tests on 10 shingle specimens. Average coefficient for the 8 groups of specimens.

(b) Extensibility

The average deflection at maximum load is listed in table 11 for samples 16, 20, and 13 and was estimated from the load-deflection data obtained from tests of the flexure specimens. Although the deflection at maximum load of the

specimens tested in a wet condition averaged about

77 percent of the deflection of the dry specimens,

the average deflection per pound of maximum

load was about 10 percent higher for the wet than

for the dry specimens.

Table 11. Estimated deflection at inaximum load ^

Sample

Condition Specimen Face

16 20 13 (max) (min) (normal)

Inch Inch Inch fUp 0.252 b 0. 179 0.199 fA iDown.. .251 .146 . 185 Dry.

ItJp b. 308 .156 . 197 LB Idowti .346 .150 .195 fUp .181 .139 .152 fA [Down .188 .133 . 163 Wet

fUp .201 .143 .154 Ib

[Dovra. .241 .123 b. 151

Coefficient of variation " 14 10 12

a Average for 5 specimens, 1 from each of 5 shingles, unless otherwise noted,

b Average for tests on 10 shingle specimens. Average coefficient for the 8 groups of specimens.

10
The deflection of the specimens at loads less than the maximum may be determined by interpolation with greater accuracy than the deflection

at maximum load. If the deflection is to be used

in specifications as a measure of the extensibility

of siding units, it is probable that the deflection at loads slightly under the maximum load rather than

the deflection at maximum load would give a more

accurate measure of extensibility. The deflection

of the samples at loads equal to 80 percent of the

maximum loads are listed in table 12 for samples

16, 23, and 18.

Table 12. Deflection at 0.8 maximum load *

Condition

Dry.

Wet.

Specimen Face

rup.-.., \Do\vnfUp,._. \Dovvn_

/Up,... \Down.

/Up.... \Down.

Coefficient of variation <

Sample

16 (max)

Inch

0.181

. 181

b. 218

.241

.123 .122 .142

. 166

23 18 (min) (normal)

Inch

0. 118

. 115

.113 .119 .102

.094 .095

.087

Inch

0. 162

I'. 149 .145

.135

. 123

. 110 .115

.109

» Average for 5 specimens, 1 from each of 5 shingles, unless otherwise noted.

i> Average for tests on 10-shingle specimens.

" Average coefficient for the 8 groups of specimens. A combined measure of both strength and extensibility of siding samples that may also be

suitable for use in speciflcations is the product of

the maximum load and the deflection at 80-percent maximum load. These products are listed

in table 13 for samples 8, 4x, and 13.

Table 13. Product of the maximum load and the deflection

at 0.8 maximum load "

Condition

Dry.:

Wet.

Specimen Face

/Up-.-.

\Dovvn.

/Up-... \Down..

/Up....

IDown..

/Up.... \Down.

Cofficient of variation '

Sample

(max)

Iblin. 11.3

b 11.9

i>8. 7 7.4

5.5 6.4

3.3 bS. 6

4x (min)

lb/in.

b 4. 5 3.3

4.6

3.0 2.2

1.6

1.9

b 1. 5

14 (normal)

Iblin

.

b 6.4

b 6.2

8.3

7.3.2

b 2.9

4.1 3.3

" Average for 5 specimens, one from each of 5 shingles, unless otherwise

noted.

b Average for tests on 10 shingle specimens.

" Average coefficient for the 8 groups of specimens.

(c) Modulus of Elasticity

The secant modulus of elasticity of the samples,

calculated at the maximum and at 80 percent of the maximum loads, is listed for samples 12, 2,

and 17 in tables 14 and 15, respectively. The

thickness used in calculating the modulus was

assumed equal for all specimens from any one

sample. This thickness was the same as that

used in calculating the modulus of rupture, table

10. As the variation in thickness between individual specimens Avas ignored, the values may be

slightly in error. The modulus of elasticity of specimens tested in a dry condition was consistently greater than that for the wet specimens

and, as may be expected, was greater at loads

of 80 percent of the maximum than at the maximum loads.

Table 14. Secant modulus of elasticity at maximum flexure load "

Condition Specimen Face

Sample

12 (max)2 (min)17 (normal)

Drv

Wet

/Up

\Down... . . /Up \Down

/Up

\IJown. .. .. /Up

\Down...

b 3, .500

3, 400

3, .500

b 3, 600 2,900

2,700

2, 900

2,700

Kipslin.^

b l,.3t0

b 1, 400

1,500

1. 400

1,300

b 1, 200

1,500

1,600

Kipslin.^

2,500

1,900

2, 300 2,300

2, .300

1, 700

2.500

2, 100

Coefficient of variation <

. 8 10 21

» Average for 5 specimens, 1 from each of 5 shingles, unless otherwise noted,

b Average for tests on 10 shingle specimens.

« Average for the 8 groups of specimens.

Table 15. Secant modulus of elasticity at 0.8 maximum

flexure load "

Condition Specimen Face

Sample

12

(.max)

2 (min)17 (normal)

Dry

Wet.

t;;::::

/Up

\Down-_

/Up

(Down.

/Up

IDown. /Up

(Down

Kips.Hn.-

b 4, 100 3,800 3,800

b 4, 300 3,300

3,200

3, 400

3, 100

Kips/in.-

b 1. 500

b 1. 600

1. 700 1,600

1, 500

b 1, 400

1,800

1,600

Kips/in.' 2,700

2, 300 2,600

2. 500

•

2, 600

2, 100 2,800 2,600

Coefficient of variation » 6 15 18

f Average for 5 specimens, 1 from each of 5 shingles, unless otherwise noted,

b Average for tests on 10 shingle specimens.

= Average for the 8 .groups of specimens. The coefficients of variation for the modidus of

elasticity at maxinrum load were significantly

greater than the coefficients for the mocMus at 80

percent of maximum load. The differences between the coefficients for the modulus of elasticity,

determinations may be due, in part, to the diffi- culty of properly estimating the deflection at maximum load.

A somewhat consistent relation was found between the absorption of the samples and theu11
modulus of elasticity. The modulus increased

with decreases in the absorption. Samples having

absorptions of 16 percent or over had secant moduli at loads of 80 percent of the maximum of

2,200,000 lb/in.- or less. From the investigation

described in the British Paper 29, it was found

that frost resistance of roofing shingles varied

with their absorption and initial modulus of

elasticity. The frost resistance decreased as the

absorption increased and as the modulus of elas- ticity decreased. These relations may provide a key to the probable weathering resistance of a

siding sample without resorting to either artificial or actual weathering-exposure tests.

IV. Tests made by the British Building Research Board

The effects of weathering on the physical properties of British asbestos-cement roofing products were observed on samples of roofing shingles * flat sheets and corrugated sheets and are described in Building Research Technical Paper 29.® Some of the test methods described in T.P. 29, and the

effects of natural and accelerated weathering are

briefly discussed below. Data obtained from

similar tests on Bi-itish roofing and American

siding samples are compared.

1. Laboratory Measurements

(a) Flexure Tests Most of the flexural tests were made on 1- by

7-in. saturated specimens loaded at the center of a 6-in. span. Some of the tests were made on

10- by 10-in. saturated specimens loaded on a line at the center of a 9-in. span, in accordance with

the method described in British Standard Specification BS 690.*^ The fiber direction was usually

parallel to the direction of bending and the flex- ural strength of the flat specimens was greatest in

this du-e(;tion. The values of Young's modulus of

elasticity of dry specimens was obtained by a djmamic method from the resonant frequencies of

forced longitudinal vibration. In a few cases the

values of Young's modulus were checked by using

data obtained in the bending tests, and good agree- ment was obtained.

The fading load on the 1- by 7-in. specimens of

roofing shingles ranged between 12 and 20 lb. The maximum loads on saturated specimens 6 in. wide, cut from samples of American siding and

loaded on a line at the center of a 10-in. span

ranged between 17 and 47 lb, with an average

value of 27 lb. The roofing shingles (British) and

the siding shingles (American) were about the same thickness, so that for an approximate

comparison of flexural strength it is only necessary

to correct for the differences in the width and

length of the specimens. On such a corrected

basis, the relative flexural strength of the roofing

shingles and of the siding samples was 2 to 1. A

similar comparison of flexural strength was ob-

< Designated as slates or flat slates in T. P. 29.

5 Buildins Research Technical Paper 29 may be purchased for 30 cents from the British Information Services, Sales Department, 30 Rockefeller

Plaza, New York 20, N. Y.

» British Standard 690:1945 Asbestos Cement Slates and Sheets may be purchased for 90 cents from the American Standards Association, 70 E. 45th

Street, New York 17, N. Y.

tained from the modulus of rupture. The average

modulus of rupture for two samples of roofing

shingles was 5,600 lb/in.-, and the average modulus

for the siding samples was 2,900 Ib/in.^ The

average modulus of rupture for two samples of corrugated sheets (table 9 of T. P. 29) was 3,900

lb/in.2

The values of Young's modulus of elasticity

given in tables 3 and 5 of T. P. 29 range from

about 2 to 2.5 million lb/in. ^ for dry specimens of

flat and corrugated sheets to values between 2.8 and 3.9 for dry roofing shingles. The average

modulus of elasticity of dry specimens cut from

siding shingles was 2.6 million Ib/in.^, and the

maximum value was 4 million Ib/in.^ The modulus of elasticity for the American siding shingles was generally less than that for the roofing shingles

and greater than that for flat and corrugated

sheets.

(b) Tensile Tests The specimens for tensile strength tests were

6 in. long and had a mmimum Avidth of % in. at tlu center. They were held at the ends by steel wedge grips. The tensile strength of saturated

specimens cut from corrugated sheets was approximately 1,700 lb/in.2 (table 2 of T. P. 29).

(c) Impact Tests Tests of impact strength were made on speci- mens 3 in. long and 1 in. wide. The bottom VA in. of each specimen was clamped in a modified Izod

machine and broken with a single blow. The

impact strength of wet specimens cut from flat slates and from corrugated sheets reported in T. P. 29 (table 9) averaged 15 and 18 Ib/in.^

respectively.

(d) Water Absorption

The method of determining water absorption

used in the accelerated weathering tests was as

follows: Specimens 7 in. long and 3 in. wide were

dried for 48 hr at 221° F (105° C) in an electric oven and weighed. They were then placed in a

steel vessel evacuated to a pressure of approximately 5 mm of mercury, and the pressure was

maintained at that value for 1 hr. Water was

then admitted to cover the specimens. After

immersion for 7 days the specimens were taken

out, wiped to remove surface water, and weighed.

12
' This test was designed to give maximum values of absorption, and it dift'ers from the test incorpo-

; rated in the British Standard 690. In that test, the

specimens are immersed in water for 18 hours and

I dried in an oven at 302° F (150° C) for 4 hi-. However, the values obtained by the two test methods are very similar.

In tables 5, 6, and 8 of T. P. 29 the range in the

: absorption of roofing shingles, flat sheets, and cor- rugated sheets are

j Roofing shingles 15 to 29 percent by dry weight.

' Flat sheets 20 to 25 percent by dry weight.

' Corrugated sheets 22 to 30 percent by dry weight.

The average water absorption of the American

i siding samples during a 7-day immersion period was 16 percent. The maximum absorption was

;j 28 percent and the minimum was 11 percent.

These absorptions are comparable to those of the

|i roofing shingles and less than those of the flat

|! sheets and corrugated sheets (British).

(e) Moisture Movement

The length changes produced by alternate wetj ting and drying were observed on specimens 7 in.

I long and 3 in. wide. The measurements were

j made with a screw-gage micrometer head sup-

' ported in a metal frame and reading to 0.0001 in. The specimens were dried in an electric oven at

I 50° C (122° F) and were cooled to room temperature in a desiccator. They were wetted by immersion in water. Some tests consisted of 240 to 480 cyles of alternate wetting and chying. One

cycle of wetting and drying was completed in 1 day. In other tests the specimens were dried for 96 hr and immersed for 7 days. The results of

the wetting and drying exposures and measure- ments are described in section IV of T. P. 29.

2. Effects of Natural Weathering

Three types of corrugated asbestos-cement sheets were laid on a roof at the Building Research Station and a portion of them were removed from the

roof and tested at intervals of 3, 6, 10, and 14

years. Visual observation of the corrugated sheets

disclosed the collection of dirt and moss growth

that was typical of roofing shingles on older buddings. Cut and broken edges of the corrugated

sheets were faded from the original light-gray

color to a drab light yellow. The discoloration was producted by the carbonation of lune. The strength tests indicated that the modrdus

of rupture and the tensile strength were not adversely affected during 10 years of roof exposure.

The impact strength was greatly reduced and,

after 14 years of exposure, was about one-half

that of the initial value.

The moisture movement (change in linear di- mensions from the dry to the wet condition) was

measured after roof exposures of 1, 2, 18, and 22

njonths duration. The initial movement decreased with increase in the duration of roof ex- posure. Sheets placed on the roof 1 month after manufacture showed higher subsequent shrinkage

than sheets aged 2 months before they were

exposed.

3. Effects of Accelerated Weathering

(a) Wetting and Drying

Length changes: The length changes and moisture movements induced by alternate wetting and

drying were aft'ected by carbonation of the speci- mens and by their age when first tested. The

effects of carbonation on moisture movement of

the specunens and on length were shown by

changing the carbon dioxide content of the drying

atmosphere. For example, one group was clried in an atmosphere free of CO2 gas. Other groups were exposed to carbon dioxide gas while drying

or were dried in air. In general, carbonation

tended to reduce the moisture movement and

both the chy and wet length of the specimens.

The amount of moistui'e movement and the

length of the specimens were also said to be affected

by a contmued hydration of the cement and the

effects by hydration on length were of opposite

sign to those produced by carbonation. Speci- mens subjected to cycles of wetting and dr^dng

10 weeks after manufacture tended to increase in length when dry. ^"NTien first dried and wetted at an age of 20 weeks or more, the specimens showed

a decrease in dry and in wet length. For example,

the data in T. P. 29 (table 12) for roofing shingles

subjected to 70 cycles of wetting and drj'ing in air indicated the foUowing:

Age when

test began

Length change at 70 cycles

Dry Wet

Weeks

9 20 to 24 %

+0. 09 -.06 %

-0. 08 -.19

The effects of age on dry length, as indicated

above, were not greatly changed by increasing the

nmnber of cycles of wetting and drying from 70 to 240 or more. There was a shght, but significant,

further decrease in wet length.

The moisture movement during the initial cycle

of wetting and drying in ah of roofing shingles

ranged between 0.17 and 0.25 percent (fig. 2 of

T. P. 29). The movement for the initial cycle of

American siding shingles ranged between 0.06 and

0.17 percent. The data obtained from only four

or five cycles of wetting and <lr3Tng specimens cut from the siding shingle indicate changes in length

and in moistm'e movement that were similar to those found for the aged samples of roofing shingles

(British). For a like number of C3^cles of wetting

13
and drying it is probable that the magnitude of the

length changes and moisture movements of the

roofing shingles would be equal to or greater than

those for the siding shingles.

Water absorption: The initial water absorptions

of the roofing shingles was about equal to that

of the siding shingles. The absorption tended to decrease with increase in number of cycles of wetting and drying. After several hundred cycles of

wetting and drying in air, the range in water

absorption of the slates dropped from an initial value of 15 to 23 percent to a range of 5 to 15 per- cent (fig. 3 of T. P. 29). Transverse strength. The transverse strength of

1- by 7-in. specimens cut from roofing shingles

increased appreciably during the first 70 cycles of

wetting and drying in air (fig. 4 of T. P. 29).

Above 70 and up to 480 cycles, a small but significant increase in transverse strength was noted.

It is probable that some carbonation of the speci- mens occurred during the wetting and drying and

that some of the increase in transverse strength

may have been caused by carbonation. This is indicated by tests made on specimens exposed to carbon dioxide gas. The transverse strength of

the specimens was increased about 20 percent by

carbonation, and the impact strength was reduced

about 20 percent, (table 9 of T. P. 29).

Modulus of Elasticity. Young's modulus of

elasticity for roofing shingles, flat sheets, and

corrugated sheets increased during the first 60

cycles of wetting and drying in air, (table 3 of

T. P. 29). No change in the modulus was noted

between the 60th and the 180th cycles. The

initial modulus of elasticity for two dry samples

of roofing shingles was 3.i million Ib/in.^; at 60

cycles of wetting and drying the average value was 3.55 million Ib/in^.

(b) Acid Rain Water

The attack of acid rain water was observed to have a surface effect, and the extent of attack was

measured as the ratio of the loss in weight to surface area. Kain water containing carbon

dioxide produced a weight loss in specimens of roofing shingles of about 0.1 g/cm^ during an immersion period of 50 weeks (fig. 6 of T. P. 29).

The rate of attack on roofing shingles of a rain

water spray containing 0.05 percent by weight of

sulfur dioxide was about 0.07 g/cm^ in 6 weeks.

A solution of humic acid in rain water had little effect on the specimens. The loss in weight produced by acid rain water did not appear to be

affected by the absorptive properties of the

specimens.

(c) Frost Action

The effects of freezing and thawing were observed on specimens 7 in. long and 1 in. wide.

The specimens were frozen in air over night at 5° F (— 15° C) and thawed by immersion in water. Determinations of modulus of elasticity were

carried out up to 140 cycles of freezing and thawing. The value of the modulus approached a maximum u-respective of whether or not marked

deterioration occurred in the specimens. The

deterioration was mainly lamination accompanied

by flaking of the specimen.

In general, the frost resistance was highest for specimens having a high initial modulus of elas- ticity and a low absorption.

V. Conclusions

1. As little information was available regarding

the method of manufacture of the American siding

samples or about the kinds of materials used in them, it was not possible to correlate these factors

with the data obtained from the tests.

2. Samples of the American siding shingles and

of the British roofing shingles had similar absorptive properties.

3. The most practical method of measuring the

thickness of the siding samples was the measure- ment of average thickness by a water-displacement

method.

4. The initial rate of water absorption through

the cut edges of specimens cut from the sidingsamples appeared to be much greater than the

initial rate through the faces or backs of the

specimens.

5. Some samples of siding showed little or no

increase in length on exposure to high-pressure

steam. There was no correlation between the

water absorption and the increase in length of samples exposed to high-pressure steam.

6. The lengths of the samples when wet and

when dry tended to become progressively smaller

with cycles of alternate wetting by immersion m

water and drying in an oven. This was also true

of the amount of moisture movement or change in length with change in moisture content. The

length changes and the reduction in the moisture

movement were attributed to atmospheric car-- bonation of the specimens. Carbonation of

British roofing products, which resulted from

both natmal and artificial weathering exposures,

had similar effects and tended to increase the

flexural strength and to decrease the impact

strength of the specimens.

7. Some of the siding samples showed little or no change in curvature on wetting and drying.

14
! and most of the samples tended to regain their

original form on drying after immersion in water. Some samples were warped badly before testing.

8. The jflexural strength of British roofing

I shingles was about double that of the American

i siding shingles and Young's modulus of elasticity for the roofing shingles was significantly greater.

9. Samples of the siding shingles were about

45 percent stronger when tested in the dry condition than when tested in the wet or saturated

condition. The deflection per pound of load was

slightly greater for the wet than for the dry

specimens.

10. Wlien the strength of the siding units was

significantly affected by the direction of bending,

the moisture movement was least in the direction

giving the greatest flexural strength. The difi'er- ences in flexural strength and in moisture move- ment on testing in different directions was probably

due to an orientation of the asbestos fibers in the

specimens.

11. The tests indicated that the flexural strength

of siding samples could be determined more easily

by measuring the maximum flexural load than by

calculating the modulus of rupture. Similarly,

the extensibility mider flexural load could be

determined more accurately by measuring the

deflection at loads slightly less than the maximum

than by estimating or attempting to measure the

deflection at the maximum, or critical load. The

product of the maximum load and the deflection at about 80 percent of the maximum load may be

a satisfactory measure of both strength and

extensibility.

12. The siding samples having a high specific

gravity also tended to have a low water absorption.

The modulus of elasticity was greatest for samples

having low water absorption.

13. The resistance to freezing and thawing of

British roofing products increased with increase

in the modulus of elasticity and with decrease in

absorption. These correlations (between absorption properties, modulus of elasticity and re- sistance to freezing and thawing) may possibly

be used as an index for measuring the probable

durability of cement-asbestos building products.

Acknowledgment is made to Joseph M. Cameron

of the Statistical Engineering Laboratory, Division of Applied Mathematics, for his able assistance

in obtaining an estimate of the variability found

among the different shingles and of the precision

of the test methods used; to Melvin E. Herrmann

for his help in preparing the paper; and to Norman

A. Seese, Jr., for his assistance in the testing

of the specimens.

Washington, May 15, 1950.

16

BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page a]

BMS32 Structural Properties of Two Brick-Concrete-Block Wall Constructions and a Concrete-Block Wall Construction Sponsored bj' the National Concrete Masonry

Association 15^ BMS33 Plastic Calking Materials 15^ BMS34 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 1 15jt BMS35 Stability of Sheathing Papers as Determined by Accelerated Aging * BMS36 Structural Properties of Wood-Frame Wall, Partition, Floor, and Roof Constructions With "Red Stripe" Lath Sponsored by The Weston Paper and Manufacturing Co 10(t BMS37 Structual Properties of "Palisade Homes" Constructions for Walls, Partitions, and

Floors, Sponsored by Palisade Homes * BMS38 Structural Properties of Two "Dunstone" Wall Constructions Sponsored by the W. E. Dunn Manufacturing Co lOjS BMS39 Structural Properties of a Wall Construction of "Pfeifer Units" Sponsored by the Wisconsin Units Co 10^ BMS40 Structural Properties of a Wall Construction of "Knap Concrete Wall Units" Sponsored by Knap America, Inc 15ji BMS41 EfiFect of Heating and Cooling on the Permeability of Masonry Walls * BMS42 Structural Properties of Wood-Frame Wall and Partition Constructions with "Celotex" Insulating Boards Sponsored by The Celotex Corporation 15jS BMS43 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 2 15^ BMS44 Surface Treatment of Steel Prior to Painting 10^ BMS45 Air Infiltration Through Windows * BMS46 Structural Properties of "Scott-Bilt" Prefabricated Sheet-Steel Constructions for Walls,

Floors, and Roofs Sponsored by The Globe-Wernicke Co * BMS47 Structural Properties of Prefabricated Wood-Frame Constructions for Walls, Partitions,

and Floors Sponsored by American Houses, Inc 20^ BMS48 Structural Properties of "Precision-Built" Frame Wall and Partition Constructions

Sponsored by the Homasote Co 15(5 BMS49 Metallic Roofing for Low-Cost House Construction 20^ BMS50 Stability of Fiber Building Boards as Determined by Accelerated Aging lOfi BMS51 Structural Properties of "Tilecrete Type A" Floor Construction Sponsored by the Tile- crete Co 10^ BMS52 Effect of Ceiling Insulation Upon Summer Comfort 15jS BMS53 Structural Properties of a Masonry Wall Construction of "Munlock Dry Wall Brick"

Sponsored by the Munlock Engineering Co 10^ BMS54 Effect of Soot on the Rating of an Oil-Fired Heating Boiler 10^ BMS55 Effects of Wetting and Drying on the Permeability of Masonry Walls lOji BMS56 A Survey of Humidities in Residences 10^ BMS57 Roofing in the United States—Results of a Questionnaire * BMS58 Strength of Soft-Soldered Joints in Copper Tubing 10^ BMS59 Properties of Adhesives for Floor Coverings 15^ BMS60 Strength, Absorption, and Resistance to Laboratory Freezing and Thawing of Building

Bricks Produced in the United States 30(i BMS61 Structural Properties of Two Nonreinforced Monolithic Concrete Wall Constructions. 10^ BMS62 Structural Properties of a Precast Joist Concrete Floor Construction Sponsored by the Portland Cement Association 15f5 BMS63 Moisture Condensation in Building Walls 15^ BMS64 Solar Heating of Various Surfaces 10^ BMS65 Methods of Estimating Loads in Plumbing Systems 15^ BMS66 Plumbing Manual 35^ BMS67 Structural Properties of "Mu-Steel" Prefabricated Sheet-Steel Constructions for Walls,

Partitions, Floor, and Roofs, Sponsored by Herman A. Mugler 15^ BMS68 Performance Test for Floor Coverings for Use in Low-Cost Housing: Part 3 20^ BMS69 Stability of Fiber Sheathing Boards as Determined bv Accelerated Aging 100 BMS70 Asphalt-Prepared Roll Roofings and Shingles I 20^ BMS71 Fire Tests of Wood- and Metal-Framed Partitions 20^ BMS72 Structural Properties of "Precision-Built, Jr." Prefabricated Wood-Frame Wall Construction Sponsored by the Homasote Co 10^ BMS73 Indentation Characteristics of Floor Coverings lOjS BMS74 Structural and Heat-Transfer Properties of "U. S. S. Panelbilt" Prefabricated SheetSteel Constructions for Walls, Partitions, and Roofs Sponsored bj' the Tennessee

Coal, Iron & Railroad Co 200 BMS75 Survey of Roofing Materials in the North Central States 150 BMS76 Effect of Outdoor Exposure on the Water Permeability of Masonry Walls 150 BMS77 Properties and Performance of Fiber Tile Boards 100 BMS78 Structural Heat-Transfer, and Water-Permeability Properties of Five Earth-Wall

Constructions 250 BMS79 Water-Distributing Systems for Buildings 200 BMS80 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 4 150 BMS81 Field Inspectors' Check List for Building Constructions (cloth cover, 5 x 7}i inches).. 300

•Out of print. [List continued on cover page iv]
BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page iii] BMS82 Water Permeability of Walls Built of Masonry Units 25{S

BMS83 Strength of Sleeve Joints in Copper Tubing Made With Various Lead-Base Solders 15^ BMS84 Survey of Roofing Materials in the South Central States 15^ BMS85 Dimensional Changes of Floor Coverings With Changes in Relative Humidity and

Temperature 10^ BMS86 Structural, Heat-Transfer, and Water-Permeability Properties of "Speedbrik" Wall

Construction Sponsored by the General Shale Products Corporation 20^ BMS87 A Method for Developing Specifications for Building Construction—Report of Subcommittee on Specifications of the Central Housing Committee on Research,

Design and Construction 15jt BMS88 Recommended Building Code Requirements for New Dwelling Construction With

Special jReference to War Housing * BMS89 Structural Properties of "Precision-Built, Jr." (Second Construction) Prefabricated

Wood-Frame Wall Construction Sponsored by the Homasote Co 15(6 BMS90 Structural Properties of "PHC" Prefabricated Wood-Frame Construction for Walls,

Floors, and Roofs Sponsored by the PHC Housing Corporation 15(5 BMS91 A Glossary of Housing Terms 15ji BMS92 Fire-Resistance Classifications of Building Constructions 30^ BMS93 Accumxilation of Moisture in Walls of Frame Construction During Winter Exposure. _ 10^ BMS94 Water Permeability and Weathering Resistance of Stucco-Faced, Gunite-Faced, and

"Knap Concrete-Unit" Walls 15^ BMS95 Tests of Cement-Water Paints and Other Waterproofings for Unit-Masonry Walls... 25^ BMS96 Properties of a Porous Concrete of Cement and Uniform-Sized Gravel 10^ BMS97 Experimental Dry-Wall Construction With Fiber Insulating Board 10<5 BMS98 Physical Properties of Terrazzo Aggregates 15^ BMS99 Structural and Heat-Transfer Properties of "Multiple Box-Girder Plywood Panels"

for Walls, Floors, and Roofs 15j5 BMSlOO Relative Slipperiness of Floor and Deck Surfaces 10(i BMSlOl Strength and Resistance to Corrosion of Ties for Cavity Walls 10(4 BMS102 Painting Steel 10^ BMS103 Measurements of Heat Losses From Slab Floors 15^ BMS104 Structural Properties of Prefabricated Plywood Lightweight Constructions for Walls,

Partitions, Floors, and Roofs Sponsored by the Douglas Fir Plywood Association... 30^ BMS105 Paint Manual with particular reference to Federal Specifications $1. 25

BMS106 Laboratory Observations of Condensation in Wall Specimens 15^ BMS107 Building Code Requirements for New Dwelling Construction * BMS108 Temperature Distribution in a Test Bungalow With Various Heating Devices 10(4 BMS109 Strength of Houses: AppHcation of Engineering Principles to Structural Design $1. 50 BMSllO Paints for Exterior Masonry Walls 15^ BMSlll Performance of a Coal-Fired Boiler Converted to Oil 15j5 BMS112 Properties of Some Lightweight-Aggregate Concretes With and Without an Air- entraining Admixture 10^ BMS113 Fire Resistance of Structural Clay Tile Partitions 15^ BMS11 4 Temperature in a Test Bungalow With Some Radiant and Jacketed Space Heaters 25^ BMS115 A Study of a Baseboard Convector Heating System in a Test Bungalow 15(S BMS116 Preparation and Revision of Building Codes 15^ BMS117 Fire Resistance of Walls of Lightweight-Aggregate Concrete Masonry Units 20(S BMS118 The Stack Venting of Plumbing Fixtures 15(4 BMS119 Wet Venting of Plumbing Fixtures 20^ BMS120 Fire Resistance of Walls of Gravel-Aggregate Concrete Masonry Units 15^ BMS121 Investigation of Failures of White-Coat Plasters 25(i BMS122 Physical Properties of Some Samples of Asbestos-Cement Siding 15^ BMS123 Fire Tests of Wood-Framed Walls and Partitions With Asbestos-Cement Facings 15^ BMS124 Fire Tests of Steel Columns Protected With Siliceous Aggregate Concrete 15^

*Out of print.