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BMSl Research on Building Materials and Structures for Use in Low-Cost Housing lOfi BMS2 Methods of Determining the Structural Properties of Low-Cost House Constructions 10^ BMS3 Suitability of Fiber Insulating Lath as a Plaster Base 10^ BMS4 Accelerated Aging of Fiber Building Boards 10^ BMS5 Structural Properties of Six Masonry Wall Constructions 15^ BMS6 Survey of Roofing Materials in the Southeastern States 15^ BMS7 Water Permeability of Masonry Walls 10^ BMS8 Methods of Investigation of Surface Treatment for Corrosion Protection of Steel 10^ 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 lOjS 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 Identation and Recovery of Low-Cost Floor Coverings 10^ BMS15 Structural Properties of "Wheeling Long-Span Steel Floor" Construction Sponsored by

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Fir Plywood Association 10^ BMS31 Structural Properties of "Insulite" Wall and "Insulite" Partition Constructions Sponsored by The Insulite Co 15j5 [List continued on cover page m]
UNITED STATES DEPARTMENT OF COMMERCE • J

esse H. Jones, Secretary

NATIONAL BUREAU OF STANDARDS • Lyman J. Briggs, Director

BUILDING MATERIALS

and STRUCTURES

REPORT BMS98

Physical Properties of Terrazzo Aggregates

by

DANIEL W. KESSLER, ARTHUR HOCKMAN, and ROSS E. ANDERSON

ISSUED M AY 20, 1943

The National Bureau of Standards is a fact-finding organization;

it does not "approve" any particular material or method of construction. The technical findings in this series of reports are to be construed accordingly

UNITED STATES GOVERNMENT PRINTING OFFICE • WASHINGTON • I943

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Foreword

The extensive use of terrazzo in a wide variety of buildings and some variability in

its performance have caused a demand for more specific information on the materials

used in making this product. Samples supplied for this investigation were secured from

practically all of the domestic soiu'ces, and the producers are responsible for the selection

of samples that are representative of the various aggregates. Since a few of these

aggregates have been reported to give trouble in terrazzo mixtures, certain studies were made on these to determine if they contribute to excessive shrinkage in terrazzo mixtures.

The laboj'atory studies reported herein were made to supply data on the aggregates that

may be usefid in controlling the quality of terrazzo and adapting it to various service

conditions.

Lyman J. Briggs, Director.

[n]
Physical Properties of Terrazzo Aggregates

By DANIEL W. KESSLER, ARTHUR HOCKMAN, AND ROSS E. ANDERSON

CONTENTS

Page

Foreword ii

I. Introduction 2

II. Description of aggregates 2

1. Color 4

2. Mineralogical classification 5

3. Texture 5

4. Structure 5

5. Fabrication 5

III. Description of tests 6

1. Wear resistance 6

2. Toughness 7

3. Absorption 7

4. Bulk specific gravity . 7

5. Dust content 8

6. Percentage of voids S

7. Thickness grading . 9

Page

III. Description of tests—Continued.

8. Dimensional changes 9

(a) Moisture effects 9

(b) Temperature effects 9

IV. Results of tests 10

1. Wear resistance 11

2. Toughness 11

3. Absorption 12

4. Bulk specific gravity 12

5. Dust content 12

6. Percentage of voids 13

7. Thickness gradings 13

8. Dimensional changes 17

(a) Moisture effects 17

(b) Temperature effects 17 V. Summary 18

ABSTRACT

Terrazzo s])ecifications seldom afford adequate control over the quality of the aggregates, and since troubles sometime occur that are attributed to faulty

aggregates, this investigation was undertaken to supply

data on certain properties of the marbles usefi for making terrazzo chips. Comparative data are given on 77 samples of the commonly used products. Sanijfles were supplied by 24 producers representative of various

quarries in 12 States. The abrasive resistance, bulk

specific gravity, absorption, and toughness tests were made on the rock in the original condition, and the percentage of dust, percentage of voids, and thickness grading tests were made on samples of No. 2 chips.

Moisture-expansion tests were made on a few samjiles,

including two thought to be faulty. Thermal coeffi- cients were determined for one sample in three dii-ec- tions at right angles to each other. A few samples were found to be rather low in abrasive

resistance and friable enough to produce a considerable amount of dust in their shipping containers. Bulk

specific gravity and absorption values varied consider- ably for the entire series and also for samples of similar mineral compositions.

The percentages of voids in chips of No. 2 aggregates were determined for samples when poured into a

volumetric measure and also when compacted by vibrating. The void space obtained for loose chips is assumed

to be comparable to that of portions measured by work- men in mixing, whereas the values for the vibrated

samples give an indication of the minimum amount of cement paste required in a well-rolled terrazzo floor. Since it is commonly believed that flat or thin chips

are undesirable, a test was devised to separate samples

of No. 2 aggregates (chips passing % in. and retained on }^-in. mesh) into four thicknesses. The percentages

of particles in each of these fractions show characteristic differences for samples that are similar in other

properties. The shape of the particles seems to bear no

relation to the type of crushing equipment used, but is a characteristic of the rock. A few terrazzo slabs were made with chips of unusual thickness distribution and

were cut through the middle for studying the orientation of flat or elongated chips in the finished product.

These show a tendency for such particles to assume

horizontal positions when the terrazzo mixture is rolled, and thus interfere with the removal of excess cement paste. One sample showed a large expansion while absorbing

water, the amount being about equal to that of a

70° C temperature change, but the expansions for other samples were comparatively low. Contractions of tlie samples while drying were about the same as expansions

while soaking. Thermal-expansion measurements on

an impure calcite marble over the range —24° to + 60° C gave variable coefficients over different temperature intervals, and for different directions in the

stone. The highest coefficient (0.0000087) was obtained when the specimen was cooled from 60° to 0° C.

[1]
I. INTEODUCTION

Terrazzo floors are usually made with 1 part

of Portland cement and 2 parts of crushed

marble (usually by volume), the aggregate

sizes varying from }i to in. The colors are obtained by selecting aggregates of the desired

hue and sometimes by adding a pigment to the

mixture. Grinding the surface to expose the

aggregate brings out the aggregate colors. The

color scheme in any installation limits the

number of aggregates from which the choice can be made, particularly if certain shades of

red, yellow, and green are wanted.

In recent years, specification writers have

shown a desire to place certain qviality requirements on terrazzo aggregates, especially on

the abrasive resistance. Since little information was available on many of the marbles used

for terrazzo aggregates, this study was undertaken mainly to supply basic data for quality

control. Incidentally, some attention was giv- en to determining the causes of failure in a few

cases where monolithic floors have cracked

excessively.

Through the cooperation of the National

TeiTazzo and Mosaic Association and the aggregate producers, a representative collection of samples was obtained and tested to secure comparative data. The samples consisted of solid

blocks of stone in its original state and also parcels of No. 2 aggregate (chips passing %-in.

and retained on Yi-in. openings). Each sample was selected by the producer to represent the

average quality of a particular grade or variety of his product. Since most deposits of stone vary appreciably in diflferent ledges or parts of one ledge, it should not be expected

that the test results reported herein for particular products will conform exactly with

those of materials of the same designations

supplied in future years.

II. DESCRIPTION OF AGGREGATES

The chief characteristics of the materials and

the methods used by producers in preparing the

aggregates are briefly described in table 1. For

most samples it was necessary to determine the

classification, texture, structure, and color

from the samples submitted, because examinations of the quarries were not feasible. Geological reports on the deposits were consulted

whenever available, because such features as texture and structure are not always well defined in small samples. Details of the methods

used in selecting the descriptive terms are outlined in the following sections.

Table 1.

Description of raw materials and fabrication processes

Source and description of raw materials Equipment used for crushing and

grading

Sample number

Source riassifioation

Color

Producer's

designation ISCC-NBS 1 designation

Texture Structmc Type of crushers Types of sieve openings

9..

10- n_

12_

13.

Gantt's Quarry,

Ala. Canon City, Colo do

Calcite. White. White.

.do.

.do.

.do.

.do. .do.

Dolomitic. do

Calcite

do..... Dolomitic. dodo

Red.... Yellow.

Red....

Blue... Yellow.

.do.

.doCarbonaceous

calcite. Dolomitic

Black.

Dusky red * Moderate yellow.. Weak purplish red Weak orange pink- Medium gray ^ Weak yellow Pale reddish

brown. Dark grayFine.

..do..

..do..

..do.. ..do..

..do., .-do..

..do..

Stratified. Gyratory. Massive

...do 16 Stratified... do Massive

Stratified >». do

Jaw; hammer mill do

do

dodo .... do

do

Cream

.do.

-do-

-doCalcite. ...-do.. ....do..

Pink...

Green.. Yellow.

Weak purplish

pink. Pale red * Light olive gray... Light brownish

gray.

-do.

.do.

-do.... -do....

.do..-.

-.do IS-,

..do '»..

.-..do i«. do IS. do '9.

.do.

.do.

.do. .do.

.do.

Square. Do.

Do. Do.

Do.

Do. Do.

Do.

Do. Do.

Do. Do.

Do.

See footnotes at end of table.

[2]
Table 1.

Description of Taw materials and fabrication processes —Continued

Source and description of raw materials Equipment used for crusiiing and

grading

Source Classification

Whitestone, Ga.

do.

Cardiff, Md_

do Asliley Falls,

Mass. West Stockridpe, Mass. Winona, Minn

-do- Carthage, Mo.

---do—.

Herculaneum, Mo.

do

do -. do -.. ----do Sainte Genevieve, Mo.

Easton, Pa --

Williams, Pa

Nottingham, Pa_

do Ashbury, Tenn_

-

Friendsville,

Tenn.

---do Concord, Tenn-._

- .do.- --- -.-do Llano, Tei --

--do. -do. -do.

-do- do Marble Falls, Tex

-.--do

- do- do

-

-do-

. --do

-do

---do Bertram, Tex-

.--do Sudduth, Tex-

----do

Burnett, Tex.-

-.do Sipe Springs, Tcx- -do

Oak Hill, Tex- Hooper, TeiTalcose

mite. do

Serpentine

do-... DolomitCdoloCalcite.

DolomitiC- doCalcits- do-

-do. -do-

-do-

-do- -do-

-doSerpentincDolomitic--

Serpentine-

- . . do

Calcite ----do

-do-

-do-

-do-

-do. SerpintincDolomitic--

])olomite--- SerpentineDolomite.--

----do Hcmatitic dolo- mite. ----do Polomitic

Calcite Carbonaceous

calcite. Dolomitic- . Carbonaceous

calcite. Calcite- -

-

Siliceous calcite

-

-do

DolomiticCalcite.

do.. ---do

Hemititic calcite

CalcitfeLonghom Cavern,' Tex.

'

See footnotes at end of table.

-do-

. doColor

Producer's

designation ISCC-NBS I designation

Texture

White-,

-do. GreenLight green White

.doPinkBufC.

Cream.

Green.

.

lyight green Dark green- Gray

Pink Dark cedar- Cedar Gray

Pink

Green

Blue-.. White.

Green.

Blue.-. White- Red--,

Salmon - Red

Cream -

.

Black.

.

Pink---

Black..

Yellow. .--do— RedPink- Brown.

Red-... Cream.

Red.... AmberCream

-

Sienna

Light gray. do Dusky green ». Weak green. White

Weak yellowPale brown Medium gray. Light gray

Yellowish gray Weak orange pink

Yellowish gray.-- do

Pale brown ' Very pale orange

-

Weak yellow

green. Light yellowish brown. Very dusky green

.

do

Pinkish gray Weak pink

Weak purplish red Dusky red purple . Pinkish gray Moderate pink Dusky yellow

green.' Dark bluish gray '

.

I/ight bluish gray" Weak yellow

green.'" Medium bluish

gray. Yellowish gray Dusky red Weak reddish brown, n

Palo reddish brown

Yellowish gray

I )ark gray Very pale brown - - Dark gray Dark yellowish

orange. ---do

Pale reddish brown

Reddish gray Moderate reddish brown. Moderate pink Very palebrown . Moderate reddish brown. Moderate brown Weak yellowish

orange. Very pale brown -

.

Light yellowish brown.

Fine-

.-do..

Medium

-.do

Fine.

.do- Coarse.

-.do.... Fine - -- .--do---

..-do- —

.--do—

-

.--doCoarse.

FincCoarse. .--do—

-

---do.-

---do-- ---do- ---doMedium

Fine

Medium

CoarseFine- - -

-do--. .--do—,

—do..-,

--do---. —do—.

—do—.

--do---

Coarse

.

-do---- Fine--.

Coarse

-

Fine - - -

--do- -do- -do—

.-do--

.do-

.doStructurc

Laminated

-

.do. Veined-

.do. Massive.

Veined...

Stratified

-do .do--, -do-.. Massive "

do

Stratified- do '9- do !«_- Massive...

-do.

Stratified- Veined.

doMassive. do—

dododo.. doVeined. Massive "

----do Veined

Stratified- Massive. do 18- -do isdo 19-. do 18-- Stratified. Massive

Stratified

do- - Massive

-do--, .do 16

Stratified-. Massive ^i-

--..dO 18- ._-.do-. -do-

-do--

Stratified i«

Massive i8..

Type of crushers Types of sieve openings

Gyratory; rotary

crusher. Hammer mill Jaw; gyratory

crusher; rolls. do

Jaw; rotary; rolls- Gyratory; roll mill Gyratory; jaw;

rotary. do

Gyratory; jaw

Gyratory

Jaw; hammer mill do

dodo

do Ring

Jaw; roller

-

Jaw; gyratory- Jaw; roller- do- Hammer mill Jaw; grinder; ro- tary. do Hammer mill do—

do Jaw ; hammer mill: cone. dodo

Jaw; hammer mill;

roller. do

---.do Jaw; hammer mill; cone, --.do

do

do

do

Jaw; hammer mill;

roller. do - Jaw; hammer mill: cone. Jaw; hammer mill;

ro Her.

. ..do Jaw; hammer mill: cone. do

Jaw; hammer mill;

roller. dodo

do

do Jaw; hammer mill; cone. ...do...

[3]
Table 1.

Description of raw materials and fabrication processes—Continued

Source and description of raw materials Equipment used for crushing and

grading Samnle number

Source Classification

Color

Producer's

designation ISCC-NBS 1 designation

Texture Structure Type of crushers Types of sieve openings

65. 66-

67_

69.

70.

71 _ 72.

73-

74.

75.

76. 77-

Middlebury, Vt. Brandon, Vt

dodo

Swanton, Vt- Roxbury, Vt- Danby, Vt

Isle LeMotte, Vt.

Pittsford, Vt

Harrisonburg, Va

doItaly-., doCalcite_..- Dolomitic- do

White.

Pink.- ._-dO—

-doHematitic dolo- mite. Serpentine

Cream

Red

Green..

Calcite Carbonaceous

calcite. Calcite Carbonaceous

calcite. do

Calcite do

White.

Black.. White.

Black.

White Weak red purple .

.

Weak orange pink.

orange. Weak yellowish

orange. Moderate reddish brown i'. Very dusky blue

green. White Dark gray White Dark gray.

Fine..

..do..

...do..

..do..

...do..

Coarse. Fine. .

.

.do.

.do.

Veined.

do..

do..

do... Massive.

Veined.. do. . Stratified.

Gyratory: roller.

.

do

do

do

Gyratory.

do..... ...do

....do.

.do. do Weak yellow... Yellowish gray

.

.do.

.do. .do.

Veined

Stratified. do Massive >8. Stratified-.

do Hammer mill. Jaw; gyratory. Gyratory

do

Square. Do.

Do. Do. Round.

Do. Do.

Do.

Do. Do.

Do. Do.

Do.

1 Inter-Society color council-National Bureau of Standards.

2 Occasional white spots.

3 Light gray veins.

* Light gray areas.

' Light gray veins.

' Frequent light yellowish brown areas.

7 Weak yellow green veins.

8 Light gray veins.

9 White veins. w Dark gray specks.

1' White and medium gray veins.

" Frequent moderate yellowish orange areas.

'3 Frequent light gray spots, n Medium gray veins.

15 Frequent white chalky inclusions.

16 Irregular fractures.

1' CelluLir st rued no (travertine).

18 irrepiil:!! It.icIiiu's, mostly healed.

i» Some crlliiLii pdi tions.

20 Frequent brown chalky lenses.

21 Yellowish calcite pebbles in a pink grounil mass.

1. Color

Most aggregates on the niai-ket have trade

designations based on color, but in order to convey a more accurate conception of the

diffei'ences between the so-called reds, greens,

yellow^s, etc. from various sources, more specific

terms are desirable. The method ^ used in

designating the color teims in column 5 of table 1 has been employed in several other

fields."

1 Deane B. Judd and Kenneth L. Kelly, Method of desigiiadny colors,

J. Research NBS Z3, 3.5.5 (1939) RP1239.

2 Delegates from the following national groups have approved the method of color designations recommended by the Inter-Society Color Council for the description of drugs and chemicals: American Association of Textile Chemists & Colorists. American Ceramic Society. American Psychological Association. American Society for Testing Materials. Illuminating Engineering Society. National Formulary, American Pharmaceutical Association. Optical Society of America.

Technical Association of the Pulp & Paper Industry. United States Pharmacopoeial Convention. This method has also been adopted by the United States Department

of Agriculture for the description of the colors of soils (T. D. Rice, Doro- thy Nickerson, A. M. O'Neal, and James Thorp, Preliminary Color Standards and Color Names for Soils, U. S. Department of Agriculture Misc. Pub. 425), and it is one of the provisions of the American War

Standards (Z44-1942) for the specification and description of color.

In column 4 of table f are given the pi'Oducers' color designations, so far as they indicate a color. Where a producer has two or more

shades of one color, his designation usually

distinguishes between them by such terms as

''light green" and "dark green." These terms

are sufficient to distinguish the colors of these

pai'ticulai' pi'oducts, but his light green may

differ greatly fi-om some other pi-oducer's light green. The terms in column 5 are intended to overcome this objectionable feature of trade

designations by rating all the samples by

reference to a single standard, and the following

is a brief outline of the method used.

The first step was to determine the Munsell

notation of the color by visual interpolation on

the Munsell color scales. A gray mat with

perforations was used to give a uniform backgi'ound, and the interpolations were made by

viewing the samples and scales perpendicularly

with daylight strildng them at 45 degrees.

From the Munsell notation for each sample

the color designations were found by means of charts showing the standard designations apply-

[4]
iiig to various ranges of Miinscll hue, value,

and chroma. Each designation appUes to a considerable color range. Furthermore, colors

falling on boundaries of these ranges may take

any of the contiguous terms. The color terms

used in table 1 apply to the predominant

colors of the samples. Mottled or prominently

veined samples are described more specifically

by the footnotes to table 1.

2. MiNERALOGICAL CLASSIFICATION

Classification of the materials was determined

for most samples from the results of such

physical tests as density, hardness, and absorption, along with etching tests with cold dilute

acids. In a few instances where such means

did not give conclusive results, thin sections were made for microscopic examination, antl for two samples it was necessary to make

partial chemical analyses. The samples composed mainly of calcium carbonate were classi- fied as calcites, and those near the theoretical

composition CaMg(C03)2 were called dolomites.

Several samples were intermediate between

calcites and dolomites, and these were called

dolomitic marbles. Impure materials like the

black marbles or the highly siliceous varieties were indicated by modifying terms, such as carbonaceous or arenaceous, to denote the

nature of the main impurity. All the green

samples were classified as serpentines (hydrous

silicates of magnesia and iron). Of the 77

samples included in this study, 44 were calcites, 9 dolomites, 16 dolomitic marbles, and 8

serpentines.

3. Texture

The marbles were graded into three textures,

namely fine, medium, and coarse, depending on

the grain diameter. The system recommended

by Dale ^ was followed, except that all grades

with maximum grain diameters less than U.75 mm were designated "fine", and all with

maximum grain diameters of 1.5 mm or greater were designated "coarse." No attempt was made to grade the serpentines because of

' The Commercial Marbles of Western Vermont, U. S. Geological Survey Bulletin 521 (1912).

tii(>ir varial)ility. The mmeral serpentine is fibrous, but the rock is usually a mixture of serpentine with other minerals, such as magnetite, pyrite, hornblende, talc, calcite, dolomite,

and magnesite, the carbonates commonly

forming the white veining material.

4. Stiiuctore

Structure refers to the arrangement of the

mineral constituents. The common terms

"stratified" (parallel ari-angement) and "massive" (no definite arrangement in layers) are applicable to the greater portion of the samples.

Some marbles show no definite signs of stratifi- cation but contain veining matter of different

color or composition from that of the main

portion. The serpentines are good examples

of such structure, but it is often found in calcites or dolomites. Although these are massive rocks, their structures are better

defined by the term "veined." Two samples,

numbers 14 and 15 in table 1, contain frequent

parallel layers of talc along which the rock can be easily split. Such structures are defined as "lammated."

5. Fabrication

Preparation of aggregates for the market is a

three-stage operation, namely removal of the

rock from the quany, crushing, and grading.

Where the rock is used only for aggregate, the

common means of removal from the ledge is blasting. Quarries producing building stone use channeling machines to remove large blocks

from the ledge. These large blocks are then

sawed in slabs or smaller blocks, and only the

waste material is crushed for aggregate. Crushing machines are of six types, namely gyratory,

jaw, hammer mill, roller, ring, and cone. Some

producers do the crushing in one operation, but

most of them do it in two stages. The primary

crushing is ordinarily done Avith a jaw or gyratory crusher and the final with a hammer mill or roller. After crushing the rock, it is necessary to remove the fine particles and grade the chips

into thi'ee sizes, as follows: No. 1 aggregate

[5]
passes a Yi-in. sieve and is retained on the ^s-in. sieve; No. 2 passes a %-'m. sieve and is retained on the y4-in. sieve; No. 3 passes the K-in. sieve

and is retained on the %-in. sieve. Chips

smaller than }^-in. are not used in terrazzo. Sieves are of two types, namely round hole and

square hole. Round-hole sieves are made of sheet' metal with circular perforations, and

square-hole sieves are made of wu'e mesh.

III. DESCRIPTION OF TESTS

1. Wear Resistance

Abrasion tests were made with the apparatus

shown in figure 1.^ This consists essentially of a power-driven grinding lap, A, 10 in. in diameter, which is revolved at 45 rpm; tliree specimen holders, B, with superimposed weights,

^ D. W. Kr-sslor, }]'ear resistance of natural stone flooring. BS J. Research H, 635 (1933) RP612.

and gears, C, for revolving the specimen; and

a means of feeding abrasive at a constant rate

to the lap. The guide rings, D, are clamped in

position slightly above the specimen holders,

and the 2,000-g weight bearing on the specimen

is the combined weight of the specimen holder,

vertical shaft above with the attached spur

gear, and a weight hopper, E, containing additional adjustment weights. The frame, F,

carrying the guide rings is adjustable vertically

to accommodate dift'erent specimen thicknesses.

Gears, C, are adjusted on the shafts for each

specimen thickness, so they are slightly above

the plate, G, throughout the test. The test specimens were 2 by 2 by 1 in., and

eight were prepared from each sample in such a way as to give the wear resistance for two

directions perpendicular to each other. For

stratified materials, four specimens were pre- pared with the 2- by 2-in. faces (those abraded)

[6]
parallel to the bedding direction and four others

with these faces perpendicular to the bedding.

For samples showing no stratification, half of the specimens were cut with the test faces

parallel to some arbitrary direction and the

others perpendicular to that direction.

After the specimens were dried at 105 ±2° C

and weighed, one was inserted in each specimen

holder and abraded with No. 60 artificial corun- dum for 225 turns of the lap. The final weights were determined, and the wear resistance {Ha) was computed by the formula „ _ 106'(W, +2000)

" 2000 Wa '

in which G is the bulk specific gravity, Ws is the

average weight of the specimen (original weight

plus fnial weight divided by 2), and Wa is the

difference between the original weight and final weight of specimen. The results are expressed

as reciprocals of the volume abraded in order to give values in the same order as those commonly

used for expressing the hardness of minerals.

2. Toughness

The resistance to impact, commonly called

toughness, was determined with the apparatus

shown in figure 2. It consists of a heavy iron

base, A, with a device for holding the specimen,

B. The plunger, C, is held in position in the

sleeve, D, and the lower end rests on the specimen, is a 2-kg weight which drops on the

plunger from variable heights until the specimen breaks. The test procedure (Standard

Method of Test for Toughness of Rock ASTM

Designation D 3-18) followed in this study was

to drop the weight from successive heights of

1, 2, 3, or more centimeters imtil the specimen

broke, and the height of the last drop was taken

as the toughness index. The operation is mechanical except that the operator controls the

height of each drop of the weight with the

crank, F. The tests were made on two cyhndiical speci- mens 1 in. high and 1 in. in diameter cored from

each sample. The stratified samples were cored

with the axis of specimens ])crp('ii(li( ular to the bedding, whereas the others were cored in any convenient direction. The ends of the

cores were finished by grinding them to smooth,

parallel surfaces. Before the tests were made

the cores were dried for 24 hr at 105° C. Since

the lower end of the plunger is rounded, it has

a mild chiseling action, which usually splits the

specimen in two or three pieces, as shown by

the broken specimens in figure 2.

3. Absorption

The 2- by 2- by 1-in. specimens prepared for the abrasive-resistance tests were used for absorption and bulk specific gravity determinations before the abrasion tests were made.

These blocks were dried for at least 18 lu' at 105° ±2° C, cooled, and weighed to the nearest

0.01 g, then totally immersed in water at 20° ±5° C for 48 hr. They were then removed

from the bath, surface dried with a towel, and

weighed again.

The results are computed by the formula

Absorption (%) = Ei^xi00,

in which Wi is the dry weight of the specimen,

and W2 is the weight of the specimen after soaking it for 48 hr.

4. Bulk Specific Gravity

After the final weighing for the absorption

test, the specimens were again inmiersed in water to maintain them in a soaked condition

until their volumes could be determined. This was done by weighing them suspended in water. The bulk specific gravity was computed by

the formula

W2-W,'

in which Ws is the weight of the specimen sus- pended in water. No density corrections were

applied for the water temperatures, since a high degree of accuracy was not necessaiy.

[7]

516850—43 2
FiGUTiK 2. —Toughness apparatus

used for determining resistance to impact.

5. Dust Content

The dust content, i. e., the portion of the

sample that could be washed tlu'ough a No. 100

sieve, was determined on samples of No. 2 aggregate. The entire sample received from the

producer was used, because it was found verydifficult to mix the sample so the dust would be

uniformly distributed through all portions, and

for this reason the samples varied in weight

from about 1 to 5 lb. After drying the sample

at 105° ±2° C and weighing it to the nearest

0.01 g, it was placed on a No. 8 sieve nested in a No. 100 sieve. The sample was then washed

with a stream of water until the water passing

through the lower sieve ran clear. The sieves

and their contents were then thoroughly dried

and the material on them weighed. The dust,

i. e., the difference between the original and

final weights of the samples, is expressed as a percentage of the original dry weight.

6. Percentage of Voids

This determination was made on samples of

the aggregate averaging about 1 lb in weight.

A glass measure was made for this purpose by

cutting off the top of a Pyrex beaker, then

grinding the top edge until a ground-glass cover

plate made perfect contact at all points. The

volume of the container was determined by first

[8]
weighing it empty, then full of water, and

finally dividing the weight of the water by its density. The percentage of voids of the samples were determined for two methods of filling the measure: (1) pouring the aggregate slowly from

a height of about 10 in. while the measure was

rotated slowly, and (2) by fastening a strong

paper around the measure so that it extended

1 in. above the top, filling with aggregate to the

top of the paper, then vibrated on the table of a vibrating machine for 10 min. In both methods

the excess aggregate was carefully leveled off imtil the cover plate made contact with the top

of the measiu'e at all points without being

pressed down. In the vibration method the measure was set on a rubber mat on the vibrator

table (frequency 3,450 cycles /min, and amplitude 0.003 in.) and- held in place by a ring

slightly larger than the outside diameter of the measure. The weight of aggregate required to fill the measure was divided by the bidk specific

gravity of the sample to obtain the volume of the particles. The difference between the

volume of the measure and that of the particles

gave the void space. The results are expressed

as a percentage of the bulk volume of the

material.

7. Thickness Grading

A special type of sieve was constructed for

this test, consisting of a box about 8 in. square

and 1 in. deep. The bottom and two sides were made of K-in. brass plates, and the other

two sides were wood. The brass sides were

adjustable vertically so that slots of any desired width could be formed with the bottom

plate. By means of gage blocks the slot width was made %6 in. for the first test, }i in. for the

second, and Xe in. for the third. It was found

that the slot width for any one setting did not

vary more than 0.003 in. at any point from that

of the gage thickness.

The specimens used in the thickness-grading

tests were obtained by thoroughly mixing the

entire sample on a large sheet of strong paper,

quartering, and taking diagonally opposite

quarters. The slots were first adjusted to /(e in., and a 200-g sample was put on the sieve

and sieved by hand with a rotary motion, first sieving from one slot and then the other to avoid clogging as far as possible. The part

remaining on the sieve was weighed. The slots were then set to Yg in., and the part passing

through the ^{e-in. slot was resieved as in the

first operation. This was followed by resieving

with the Ke-in. slot the part passing the %-m

slot. The weight of each fraction is expressed

as a percentage of the entire specimen.

8. Dimensional Changes

(a) MoiMure E;ffects Linear measurements were made at controlled temperature (73° ± 2° F) on a few speci- mens while they were absorbing water and

also while drying. A Tuckerman optical strain

gage ^ reading to 0.000002 in. was mounted

along the diagonal of the 2' by 2' by 1-in. specimen, giving a gage length of 2 in. The

dried specimen was laid on microscope slides

in a glass dish and, after taking the original

reading, a sufficient amount of water was

poured in the dish to bring the level about

one-tliii'd of the way to the top of the specimen.

Readings of the gage were taken at 2-hr in- tervals during the first 8 hr. and at convenient

intervals during the days following. Wlien no further expansion occurred the water level was raised neai'ly to the top of the specimen

and readings continued until the maximum

expansion was recorded. The water was then

syphoned oft', and readings were made durmg

the drying period until the minimum was

reached.

(6) Temperature Effects. Linear expansions were measured at controlled humidity over the temperatm'e interval —24° to -f 60° C by the interferometer method.^ The specimens were made in the form

of a tripod with legs averaging about )'i in. in height. These were dried at 105° C and

' L. B. Tuckerman, Optical strain gages and e-Ctensometers, Proc. Am.

Soc. Testing Materials, 23, pt. 2, 602 (1923).

' G . E . Merritt, The interference method of measuring thermal expansion, BS J. Researcli 10, 59 (1933) RP515. J. B. Saunders, Improved interfero- metric procedure with application to eipansion measurements, NBS J Research «S, 179 (1939) RP1227.

[9]
put between fused quartz plates in a specimen

chamber, the humidity of which was maintained at a low level by means of a desiccant.

Specimens of stone usually expand at a higher

rate than fused quartz, and hence some

horizontal slippage occurred between the two

materials as the temperature was varied.

By weighting the upper quartz plate with a small U-shaped bar of lead over the leg of the

specimen near the reference point where meas- urements were made, the slippage was confined

to the other two points of contact. The temperature was lowered to —24° C for the first leading and raised at the rate of 1° C each 3 min. Expansion readings were made at about

7° C intervals. After the reading at -1-60° C

was obtained, the temperature was then lowered at a rate of 1° C in 3 min until 0° C was

reached, contraction readings being made at appropriate intervals.

IV. KESULTS OF TESTS

The results of the physical tests on the rock

in its original condition and on the crushed

material are given in tables 2 and 3. Table 2.

Results of tests on the original rock

Table 2.

Results of tests on the original rock—Con.

Sample number

Abrasive resistance (//a) Bulk

specific gravity

48-hr absorption

Toughness Direction A Direction B

Max. Min. Avg. Max. Min. Avg.

Pet. 1... - 16. 2 12.7 14.7 16.7 12.8 14.8 2.71 0. 10 6 2 18.8 17.

1

17.8 19.7 16.7 18.6 2, 76 .84 6

3 2, 74 1.06

4 31.0 19.1 23.9 30.7 16.9 21.5 2. 72 0. 56 9

5 14.2 6.8 10.0 9.7 7.9 8.9 2. 23 4. 00 4 6 33.6 27.8 31.4 34.7 29.0 31.4 2. 77 0. 07 12

7 30. 2 26.1 28.5 33.6 30.2 32. 1 2. 74 .67 6

8 30.5 21.8 25.6 29, 6 26.5 28. 1 2. 74 .58 10

9 36.4 30.

1

33.

1

35. 7 30.2 33.4 2.69 .36 4 10 30.7 26. 6 28.5 29. 2 25.9 28. 1 2. 76 .84 17

11 24.7 22. 7 24.0 23.9 21. 2 22, 4 2. 66 1.88 10

12 2,5.9 21. 6 23.0 25.0 22.5 23, 5 2. 65 0. 18 8 13 24. 4 21. 1 22.8 25.9 21.2 23.3 2. 70 .22 6 14 10.6 6.5 8.9 18.7 16.5 17.9 2. 84 .21 6

15 19. 8 14.5 16.0 30.3 26.9 28.3 2. 84 .08 9 16 47.3 34. 1 41. 5 63.0 45.0 52,8 2. 61 1. 37 8

17 52. 7 43.4 47. 1 53.7 36.9 43. 6 2. 71 0. 40 6 18 10.6 9.3 10.0 13.5 12. 0 12.6 2. 86 . 12 3 19 17.0 1.3.3 15.3 2.71 . 13 20 17.6 15. 6 16.fi 17.1 14.9 15.7 2. 63 2.02 4

21 14.0 9.8 12. 3 2. 51 2. 67 3 22 17. 1 15.1 16.0 20. 9 i7.4 18.9 2. 67 0. 29 6 23 19. 3 16. 9 18.4 20.2 16.9 19.0 2. 63 .80 4 24 ^ 32.0 25. 8 29.8 32.0 25. 3 28. 6 2. 69 .36 6

25 35. 4 30.3 32. 5 33. 5 25. 7 30.4 2. 68 . 29 6 26 29. 7 23.4 25. 9 30. 6 22, 5 26,8 2. 67 .41 5 27 30. 2 21. 5 25.0 28. 1 22, 3 24, 3 2, 52 2, 00 5 28 39.5 28. 3 35. 3 33.9 27. 7 31, 1 2. 65 0, 96 5 29 19. 3 13.9 16.8 19.

1

13. 2 16,7 2, 68 . 26 4 30 70.0 59. 8 63. 6 66.7 56. 3 61,0 2, 64 .46 24 31 _.. 22. 6 18.0 20. 2 25. 2 22. 4 23. 7 2, 82 .37 4 32 61.4 63.4 68.5 64.4 52.6 57.6 2. 66 .05 19

Sample number

Abrasive resistance (i7a) Bulk

specific gravity

48-hr absorption

Toughness Direction A Direction B

Ma.x. Min. Avg. Ma.x. Min. Avg.

33 39.3 24.

1

3L8 35.0 30.0 33.

1

2. 65 . 13 14

34 - - 22.5 18. 9 21. 2 24. 3 17.9 21.8 2. 70 .09 6 35 24. 6 20. 2 22.

1

24.0 20.

1

21.9 2. 70 .08 4

36 25.0 23.3 24. 1 26.2 21. 4 25.0 2. 72 .06 6

37 26. 5 22. 3 23.9 23.9 21.9 22.9 2. 72 .08 6 38 25,3 20. 2 23.0 24.7 20.9 23. 1 2. 70 .08 4 39 29. 5 25. 8 27.6 27. 5 24.0 25. 5 2. 71 .08 6 40 . . 14.4 10.9 12.3 19.8 12.9 15.6 2. 39 3. 23 8 41 _ . _ 14.3 12, 5 13.4 17.4 15. 3 16. 2 2. 81 0. 14 6 42 — 33.3 30, 2 32.

1

30.8 20. 3 2.5.0 2, 98 .04 8 43 10.4 9.6 10.0 9.9 8.7 9.3 2, 20 7. 43 4 44 16.9 11.9 13.4 17.0 11.3 14. 1 2. 87 0. 06 4 45 . „_ 21. 2 14.8 18. 1 20.4 16.4 18. 2 2. 89 .07 6 46 44. 6 33,3 38. 9 41,8 36. 7 39.9 2. 81 . 38 7 47 49. 4 38. 8 43.0 47.7 36,8 41.0 2. 81 . 34 12

48 - 40, 5 36. 2 39.6 42.8 38,0 40. 5 2. 79 . 47 16 49 46.8 41. 5 44.0 56.8 42.7 48.9 2. 69 . 20 4 50 _ . . 79.7 61.0 70. 7 77.0 60. 7 66.9 2, 64 . 43 33

51 _ 30. 5 27.7 29.6 30.3 28.

1

29. 1 2. 81 . 11 12 52 94.7 69. 4 78.3 83.6 61.4 76.7 2. 62 . 27 34

53 27. 4 18. 6 24.

1

28.4 20.5 24.8 2. 56 2. 02 8

54 20.8 17.2 18.8 20.8 17.5 18.8 2. 61 1. 50 6

55 _ _ 21.

1

16.0 18.0 19.1 18.1 18.4 2, 60 1. 68 5 56 ... 26.7 20.4 24. 2 31.0 26.0 28.

1

2. 79 0. 24 8

57. 25.9 22.7 23.7 26, 6 22. 2 24.7 2. 69 1. 27 6 58 32.

1

26.6 29. 6 32. 3 22, 8 27.4 2. 67 0. 69 6

69 . .- 51.8 46.3 48.6 51.8 46.8 48.6 2. 71 .08 6

60 . 31.6 27.8 29.2 33.3 30.5 32,

1

2. 64 .86 8

61. ... . 36. 8 30.0 32, 8 36.4 27. 3 33, 1 2. 64 . 68 12 62 .. .. 35. 8 30. 8 33. 5 41. 2 36. 5 38.4 2. 66 . 60 8 31.4 26. 1 29.

1

32. 1 24.0 27.6 2. 60 1. 28 8 64 . . 43.

1

37. 1 40.7 42. 5 37.

1

40.8 2. 70 0. 11 6

65 . . .

.

22. 4 17.2 19.8 22.

1

20. 5 21. 3 2. 70 . 09 4 66 39.3 26.3 32. 5 32.8 28.

1

30.6 2. 81 . 18 7 67 34. 2 26.

1

31.4 32.4 29.3 31.0 2. 82 . 19 8 68 36. 5 28, 1 31. 6 38.8 31.3 35.0 2. 81 . 26 69 40.0 34. 6 36.6 37.4 30.4 34.6 2. 83 '. 11 20

70 108.0 94, 2 99.9 126. 5 103.9 112. 2 2. 68 . 14 34 71 14.3 11.1 12. 8 16.7 11.7 13.8 2. 71 . 10 3 72 30.0 25.9 29.0 29. 5 27. 1 28.0 2. 78 . 16 10 73 19.1 14. 3 15.9 23, 1 15. 6 18.4 2. 73 . 13 4 74 37.8 33.5 36.0 32.6 30.0 31, 6 2.72 .03 6 75 38,8 34. 1 36.6 33. 6 30.6 32.0 2. 72 .04 6 76 42.8 39, 4 41. 1 41.0 38.4 40.0 2. 71 . 13 6 77 23.3 15.6 19.5 20, 1 16.8 18.9 2.46 .98 4

Table 3.

Results of tests on No. 2 chips

Sample number

9

10.

11. 12. 13.

14.. 15.

16..

17-, 18.. 19 ' 20..

21..

Dust

content

%

0. 87 .44

.47 .27

1.25

0. 21 .45

.29

.16 .22

.33

.33 .42

.37 .76

.61 .37

1.83

Void space Amounts of chips of stated thickness

Loose

0.28

1.47

%

45. 07 45.82

45.23

44. 16 39.75

44. 94

43. 13 45.93

42. 64

44. 32

41.93 42.28

46. 33

44. 36

45. 58 48.00

63,61 42.56

47.08 46.86

Vibrated

Less than Me in. (Ti) %

41. 12

43. 09 41.55

40. 35 36.63

40. 94

40. 59 41.87

39.28

40. 94

38. 34

38. 83

42. 27

40. 62 41.34

43. 31

50. 14

38. 26

43. 55

40. 32

Mo to

]4i in. (Ti)

%

0.25

.14

.42

.24

.53

%

13.50 7.32

9. 52

H to Me in. (Tz)

43.38

38. 11 41.23

10.02

9. 36

5, 64 6,48

8. 34

16, 84

18, 10

37. 38 35.03

46. 56

28. 29 37.09

57.31 49.05

Greater than Me in.

20. 30

[10]
Table 3.

Results of tests on No. 2 chips—Continued

Sample number

Dust

content

Void space Amounts of chips of stated

thickness

Loose Vibrated

Less than Me in. (Ti)

Mo to M in. {Ti)

Vi to Ym in. (Ti)

Greater than

'Mo in.

% % % % % % %

22 ... 0. 55 46. 58 42. 31 23 .74 46. 52 42. 94

24_- ___ ___ . 40 43. 74 40. 32

25, _ . 46 44.01 39. 62 1.00 4. 69 26. 51 67. 89

26 . 55 43. 50 39. 16 0. 77 5. 47 31, 31 62. 43

27 2. 08 40. 43 36. 52 6. 63 9. 85 34, 66 48 80

28 . 0. 40 43. 04 39. 19 0. 77 6. 07 35. 08 58. 07

29 . . 52 44. 89 41. 17 30 _ ... . 73 44. 86 40. 98

31 .45 44. 68 41. 46 . 75 19. 72 39. 76 39. 71 32 .30 45. 02 42. 00

33 . 38 47. 68 44.81 1.36 24. 28 47. 21 27. 14 34 . 73 45. 35 43. 42

35 . . 41) 46. 38 42. 75 0. 21 10.76 34. 18 54. 83

36 . 28 45. 04 41. 17 . 13 10, 26 53. 23 36, 40

37 . 31 44. 88 42. 61 . 20 8, 53 36. 72 54, 53

38 . 33 44. 60 42.80 .53 9, 63 39. 18 60, 63

39 ... . 39 44. 37 42, 70 .81 13, 35 36. 83 49, 00

40. _ . 62 46. 10 42, 14 1.66 18. 52 41.77 38.02

41 .61 44. 02 40, 81 0. 82 15, 84 50. 81 32. 49 42 .44 44. 95 41, 53

43 . 76 40. 36 37,70

44... - 1. 31 41.24 37. 89 1. 44 6, 64 29. 77 62. 07

45 0. 62 43. 96 40, 68 0. 63 9. 97 44. 85 44. 49 46 .25 45. 16 41, 72 . 50 6. 63 36. 27 57. 56

47 1. 13 45. 84 41,40

48 0. 37 44. 62 41, 66 1. 10 17. 84 42. 97 38. 07

49 . 38 43, 06 40, 45 1. 17 16. 80 51 36 30 66

50 _. . 27 43. 74 41, 22 0. 08 9. 34 53.80 36. 76

51 .41 45. 86 42, 58 .44 11. 37 47. 09 41.07

52 . . 45

.88

47. 55 43, 96

53 43. 42 39.94

54 .54 46.20 41.60 .87 24. 62 68.89 15. 62

55__ . 30 45. 39 41. 11 .79 14, 35 60. 93 33.97

56. ... _ . . 27 43. 19 39. 96 .08 5. 13 41.22 53.69

57 .69 44. 78 41.02

58 . 31 44.77 41. 75

59 . 17 44, 04 41. 15 .58 16. 33 46. 78 36. 32

60 . 26 45. 03 42. 62 1. 23 19 80 52. 32 26, 67

61. . . 28 45, 24 41.70 0. 12 13. 98 43.31 42.53

62__ _. . 46

. 53

44. 67 40. 90

63. _ 43. 84 40. 20 .92 17. 90 50. 52 30. 64

64 . 55 41.42 39. 04

65. 1. 25 44. 90 40. 84

66 0. 57 45. 67 41. 32 1.42 23, 61 52.59 22. 45

67 !32 44. 81 41. 52 2. 42 33. 15 54. 02 10. 37

68 .60 43. 91 41. 57

69 .33 46. 35 42. 57 0. 90 16. 23 37. 22 45. 65

70 .31 48. 57 44. 47 1. 96 23. 06 40. 92 34. 05

71 2. 07 41.81 38, 49 0. 19 0. 77 17. 00 82. 04

72 0. 36 45. 89 42, 65 1.17 18. 97 38.66 41.20

73__ 1. 94 42. 83 39. 05 0. 76 7. 37 45. 22 46. 65

74 0. 16 44. 97 41. 57 .04 4.79 49.84 45. 33 75 .09 46.47 41.77 1.62 20. 67 45. 50 32. 25 76*

77 .43 44. 29 40. 38 0. 21 11. 81 45.60 42. 38

a No sample of chips.

1. Wear Resistance

Among the aggregates studied, the serpentines, as a class, are shown to be the most

resistant to wear, and in the calcite, dolomitic,

and dolomite classifications there are no very

appreciable differences in average values, these

being, in round numbers for the order stated,

28, 26, and 25. There are rather large variations in all of these types, and although the

serpentines have high resistance as a group,

two samples in this series gave results much

lower than the average of all classes. Serpentine is a weathered form of the original deposit

and may be expected to be quite variable even

in one quarry, depending on how near it is taken from the surface of the ground or to an

open joint where it is exposed to surface water. In arriving at a suitable abrasive-resistance

value for floors, one may consider the actual

performance of marbles, which have been extensively used in tile form for a considerable period

of time. One variety of marble in this series has given satisfactory service in such buildings

as the Grand Central Station, New Yoi'k City,

for more than 25 yr. The Ha values obtained

for this marble are in the range 18 to 22. It may be assumed, therefore, that aggregates

giving such test values will prove to be durable

in terrazzo under severe conditions of foot

traffic. The average Ha value of all the aggregates tested is considerably above 20, and hence

the wear resistance of the greater portion of these should be satisfactory. One marljle gave

a test value below 9 in one direction (parallel to the lamination) and a value nearly 100 per- cent higher at right angles to that direction.

Few of the aggregates showed any appreciable

difference in the two directions. When two or more aggregates are combined for color effects, one is apt to differ considerably in hardness

from the other. In such mixtures the rate of wear on the floor will probably be governed by

the most resistant portion.

2. Toughness

The residts of toughness tests given in table 2 show the relative resistance of the materials to impact and give a measure of the coherence of the components. The average toughness for the 75 samples tested was 8 and the range from

3 to 34. This test has been extensively used on

paving materials, and the following average

values for dift'erent types of rock reported by

the United States Bureau of Public Roads ^ are of

interest. Trap rocks, including andesite, basalt,

diabase, and rhyolite have an average toughness

of 18; gabbros, 14; granite, 8; limestone, sandstone, and marble, 7; and quartzite, 15.

' Pfevost Hubbard and Frank H. Jackson, Jr., Results of physical

tests of road building rocks, U. S. Department of Agriculture Bulletin

370 (1916).
Jn niaicj'ials of low colicr-cncc llic iiidividiial grains or crystals may be (Jisiodged liiuJcr alji-a- sion and, hence wear away more rapidly than

materials with the same mineral constituents

having a higher degree of coherence. It may be

noted that all the samples giving toughness

values above 20 were very resistant to abrasion,

regardless of their mineral compositions. One

of these samples was a serpentine, one a dolomitic marble, and two were calcites. Correlations between the toughness and 11,, values for materials of low toughness are not

very satisfactory. I^'or flooi'S subjected only lo foot traffic, it is doMlifl'ul if tlie toughness of Un; aggregate is of iniich ((•iicci-n, but where heavy

trucks are used, an aggj-egatc, of iiigh toughness

is desirable.

3. Ae.sokption

The absorption of most marbles used as building stone is less than 0.5 percent, but the aver- age of all samples in tliis series is 0.7 percent.

Fifteen samples absorbed more than 1 percent,

and eight, more than 2 percent. The sample

giving the highest absorption of the series (7.43

percent) was a serpentine reported to have given

imsatisfactory pei'formance in terrazzo. Higli

absorption in itself is not deti-imental, and a

better bond between aggi'egate and cement

probably would be obtained with a moderately

porous aggregate than with one of low porosity.

Anol-her point in favor of aggregates of higher

porosity is the fact that they absorb some of the

excess water from the fresh mixture and later contribute to better curing conditions. However, a very porous aggregate in terrazzo is apt

to soil and to absorb stains more readily than one of low pore space. The absorption values

in table 2 give some information on the relative

porosities for different samples, but the actual

porosity (percentage of pores by volume) is from 4 to 6 times the percentage absorption by

weight.*

s Since the porfs of such matfrials arc usually about 50 percent fiUprl in the absorption test, an approximation of the total fiore space may be

obtained by multiplying the absorption values in table 2 by twia^ the bulk specific gravity. Multiplying the absorption values by bulk

specific gravity converts the percentage weight relation to a volume

relation.

There seems to be no relation between the

a})SOTption and abrasive resistance for any of

tlie classes of materials except serpentines. A

correlation coefficient was calculated between

these two properties for the eight serpentines,

and the result was r= —0.67. This means

that the serpentines of low absorption are usually more wear resistant than those of

high absorption, but the degree of correlation

is not sufficient to justify estimates of abrasive

resistance from the results of absorption tests.

4. Bl'lk SpEfinc Gravity

Bulk specific gi-avity was used in computing

llie abrasive resistance and void space values

gi\cn in table 2. Bulk specific gravity values

indicate the relative weights of the samples in

their original condition, and they can be readily

converted to weights per cubic foot by multiplying by 62.35. For example, sample 42 in

its original state weighs 186 Ib/ft^ Sample 43,

the lightest material tested, weighs 137 lb/ft

The df)lornites are the heaviest materials in the series. From the bulk specific gTavity and void

space of the ciushed rock one may approximate

tlie unit weight of the No. 2 aggregate by multiplying the weight of the solid rock by

1 — (void space/100) , thus : The weight per cubic

foot of aggregate of sample 42 loose (not compacted) is approximately 186X0.55 = 102 lb; and that of sample 43 is 137X0.596 =82 lb.

5. Dust Content

The average dust content in the 75 samples

tested was 0.57 percent, and the range was 0.09

to 2.08 percent. Two samples contained more

than 2 percent, 9 samples more than 1 percent,

and 46 samples less than 0.5 percent of dust. Dust particles clinging to the aggregate are considered to be unflesirable because they

interfere with the bond between cement and

aggregate. Some of the dust from the original

crushing operation clings to the aggregate and

proi)ably more is formed by grinding of the

fragments together in shipping and handling.

Exi:)eriments show that it is not possible to

[12]
remove all the dust by dry sieving, and measurable amounts are formed in sieving some materials for a few minutes. The particles of most

aggregates have sharp edges, but in some

samples submitted for this study the particles were rounded somewhat like watcrworn pebbles. This rounding was probably caused by

abrasion in handling or shipping. Most aggregates with high dust content were those in the

lower abrasive-resistance group or those having

soft chalk or clay-like inclusions. Rounded

particles should produce mixtures that are more

easily woi'ked than angular ones and thus ofl'set, to some extent, a high dust content. The dust

should not be considered as a serious objection,

because it can be easily washed off the aggregate before mixing.

G. Percentage oi'' Voids

The percentages of voids obtained on 75

samples of No. 2 aggregate by the two methods

described in section III-6 are given in table 3. The average for all the samples was 44.7 per- cent for the "loose" method and 41.2 percent

for vibrated samples. For the first method

the range of values was from 39.8 percent

(sample 5) to 53.6 percent (sample 17), and for the second 36.6 to 50.1 percent (same samples).

Although the samples were labeled No. 2 aggregate (Ya to % in.), a considerable number of them contained large amounts of particles that

would pass a K-in. square-hole mesh. On a few samples, tests were made with mixtures of No. 1 ()s to Yi in.) and No. 2 aggregates in equal

portions to obtain comparisons with results on

No. 2 alone. The voids in such mixtures were from 1 to 2 pei'cent lower than for No. 2 aggregate alone.

These values indicate that for most aggregates, the usual mixtures, namely 1 bag of cement (1 ft^) to 2 ft^ of aggregate, provides

a considerable excess of cement paste over that

necessary to fill the voids of the aggregate. In

cases where the quantities are proportioned by

weight, appreciable variations in the volume

ratios will occur for dift'erent aggregates. . For

example, consider two mixtures, one made with

aggregate A (bulk specific gravity =2. 20 and

voids=40 percent), and the other made of aggregate B (bulk specific gravity =2. 87 and

voids=41 percent). The weight per cubic foot

of aggregate A is 62.4X2.20X0.60, or 82.4 lb, and the weight of B is 62.4X2.87X0.59, or 105.7 lb. Hence 200 lb of aggregate A would

be 2.44 ft^ and of B, 1.89 ft^ The actual

volume of voids in aggregate A would be 2.44 X

0.40, or 0.98 ft^ and in B 1.89X0.41, or 0.77

ft^. One bag of cement would provide an excess of paste in either case, but for aggi'egate B

there would be considerably more excess. The rolling operation is assumed to remove,

to some extent, the excess paste, but since

cracking is reported to occur more frequently

when certain aggregates are used, it may be

assumed that the shape of particles has some

cfl'ect on the amount of paste that can be worked

out of the mixture. It is a well-established

fact that rich mixtures shrink more than lean

ones," and where monolithic terrazzo floors crack excessively, the most plausible explanation therefor is, that the mixture was too rich.

It was apparent from examinations of several

aggregates with high voids, that the shape of particles as well as gradation of sizes has a marked eft'ect on the void content. Appreciable

amounts of elongated, thin, or irregularly

shaped chips increase the voids, and equidimensional particles in various sizes decrease the

voids. The sample with the highest percentage

of voids had many slender particles up to 1 in. in length but consisted mainly of flat shapes.

One sample that consisted of very irregular

particles with rough faces and almost free of elongated or flat chips had a high pei'centage of voids.

7. Thickness Gradings

Since the results of the foregoing tests do not

afl'ord any satisfactory explanation of the cause

of failure reported by terrazzo workers for cer- tain aggregates, it was decided to study the

variations in the shapes of particles for the

« Max Gary, Trans. Am. Soc. Civil Engrs. 30. 16. (1893). M. Considere, Compt. rend. i19. -167 (1809). E. D. Campbell and A. H. White, J. Am. Chem. Soc. 28, 1273 (1906).

J. Bauschinger, Mitth. Meoh. Tech. Lab. d. Tech. Hochschule in Munchen 8th Heft. (1879).

J. C. Pearson, Eng. Contract Record 55, 187 (1921).

[13]
different samples. British and American "

specifications for crushed stone to be used in

bituminous concrete require that the aggregate

be free of excessive flat or elongated pieces.

Although there appears to be no tangible

proof that such shapes cause undesirable results, it is inferred that this requirement is based on experience. Methods for determining

the amounts of flat and elongated pieces of crushed stone have been devised at the Department of Scientific and Industrial Research

(London)

.

These methods are not well adapted for use on terrazzo aggregate sizes, since they involve

the hand gaging of individual pieces, which

would prove to be too tedious for terrazzo chips.

Although sieves with various widths or elongated holes have been used for separating

samples into various thicknesses of particles,

it was considered more feasible to construct one

sieve with adjustable slots, as described in

section 111-7, p. The pro])ortions of particles of four thick- nesses are given in table 3 for 48 samples. The

other samples were found to be poorly graded

and contained too much fine material to con- form even approximately to No. 2 chips. The

tabulated results are sufficient to show that

"> Tho British Standard Specification for Rolled Asphalt (594-1935 and

595-1935)

.

11 ASTM Specification for crushed stone for bituminous concrete base and surface courses (D 486-39T),

12 Report of the Road Research Board for I lie period ended 31st Mareli

1S35; Road Research Bulletin No. 2 "The Shape of Road Aggregate and

its Measurement" by A. H. D. Markwiok.

marked differences exist between certain aggregates with respect to the amounts and distri- bution of particles of certain thicknesses. In a majority of the samples the amount of very

thin chips was below 1 percent, but four contained more than 2 percent of this grade.

These results show at least fotir types of distri- bution, as illustrated by graphs A to D in figure 3. Graph A shows the grading of a sample for which terrazzo workers claim uniformly good

results in practice. In this, the thinnest grade

of chips is negligible, and the increase in amount

fi-om thin to thick is almost constant. Graph

B (for sample 71) shows a preponderance of chips in the thick grade, while graph C is for a sample (No. 27) with a relatively high amount

of the thinnest grade. Nearly half the samples

showed a distribution as in graph D, in which

there is a pi'eponderance of the T3 grade and a

distinct drop in the amount of T'4 chips. One

aggregate (No. 54) which some terrazzo workmen believe is the cause of poor performance in

several histallations gave this type of distribution in the tests. Graphs E to H, (fig. 3) based on averages,

are presented as evidence that the type of

distribution shoAvn in graph D tends to increase

the percentage of voids in the aggregate.

Since some samples of this type of distribution

have a lower void content than other samples

with distributions as shown in graph A, it is evident that the amount of voids in the aggregate is not a satisfactory basis for comparison.

FiGTJRE 3.

Thickness-grading

curves.

A, grading of sample 36. B, grading of sample 71. C, grading of sample 27. D, grading of sample 14. E, average grading of 48 samples.

F, average grading of samples having voids over 43 percent.

G, average grading of samples having voids over 42 percent.

/-/, average grading of samples having voids

less than 39 percent.

T, T2 T3 T, T3 r, T3 r, T, T4 TMcAness ofc/7/ps : T; 7^,£/o^"; ^, ffOyj"; > J"

[14]
FiGTJEE 4:.- Cross sec- tions of terrazzo slabs, illusirating the tendency

of fiat or elongated chips

to assume horizontal

positions.

In order to gain some idea of iiow flat or elongated particles arrange themselves in ter- razzo mixtures, made and placed as in actual

installations, several samples were obtained

from the National Terrazzo and Mosaic

Association. These were made in large slabs

by experienced woi'kmen and then sawed into

smaller slabs. Eight of these are shown in figure 4. A few thicker slabs were made in the

laboratory and cut in sections. Slabs S~l and

S-2 in figure 4 were selected from the latter group to illustrate the orientation of aggregates

having marked elongation. All these were made in the position shown, i. e., the top faces were rolled. It appears from these that long

or flat particles are more often turned with

their greatest dimensions parallel to the rolled surface. A count of the particles showingelongation in S-1 and S-2 was made, in which

the particles with inclination less than 45

degrees to the top surface of the slab were

recorded as horizontal and all others as vertical. For S-1, 70 percent and for S-B, 72 percent of the elongated particles were rated as horizontal.

The tendency for elongated fragments to assume horizontal positions m bituminous

concrete has been pointed out by Lonsdale

and Markwick (see footnote 9). Flat particles arranged mainly horizontal in terrazzo mixtures may interfere with the re- moval of excess cement paste in the rolling process, thus causing the finished product to be

too rich in cement. The failures reported re- sulted from cracking and indicate that excessive

shrinkage occurred. Variations in shrinkage,

due to richness of the mix, have been referred

[15]
60

I

I

—

o

1 1 1 Samo/e No. 28

r' r- . -0 Soak/'ng * Dry/ng^

-•

10-

0

400

I

t

-10060 40

20

0^

-20

60'

40

20

0

0

c 5a/77p/e No.c0

0

-0 O o

]5 O -0 0

<-)

np/e No. 43

O Sarvp/e No..^4

o -o

No. 56

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160' 170 180. 190

T'/'rne, hours

Figure 5.Cui-ves for four calcites and a serpentine, showing expansion of samples while soaking in water and contraction while drying.

to in section IV-6. Further studies on the

effect of flat and elongated chips in causing

richer mixtures and increasing the shrinkage

might prove to be of value.

Since there is evidence that thin chips are

objectionable, each producer was asked to supply information on the types of crushing

and grading equipment used in his plant. This

information is given in table 1. Comparisons

of various aggregates obtained by similar

crushing methods and also comparisons between

similar products obtained with different types

of crushers have been made. It was concluded

that the shape of particles is influenced more by

certain characteristics of the rock than by the

type of crusher. Studies have been made at the United States Bureau of Mines on the

amounts of flakes obtained by two types of

crushers, and the conclusion was that rolls produce more flakiness than ball miUs. Although the sizes of crushed material studied were considerably smaller than terrazzo chips,

the conclusion might justify further studies on

the shapes of particles obtained by crushing

certain materials with various types of crushers.

13 Will H. Cohgill, 0. W. Holmes, and A. B. Cambell, Determination

of Flakiness of Ores, U.S. Bureau of Mines Reports of Investigations

2899, 4896 (October 1928).

[16]
8. Dimensional Changes

(a) Moisture Effects The results of linear expansion and contraction measurements made while specimens were

soaking and while drying are shown in figm'e 5 for five samples. For all of these, except sample 43, the changes were small. Contractions

during the drying period were usually somewhat

less than the expansions during the soaking.

This probably was due to the fact that the speci- mens were oven-dried at 105° C for the original

measurement (before soaking), whereas the

final drying was at room temperature (73° +

2° F). Sample 38 showed the least changes, and

these were about equivalent to those that would

result from a 2-degree temperature change.

Sample 43 expanded very much more than any

other sample tested, and the total expansion

probably was equivalent to that which would

result from a 70-degree change in temperature.

The expansion continued over a period of about

6 days, and 70 percent of the total occurred

during the first 30 hr. The contraction was more rapid than the expansion, and most of it occurred in 1 day.

Expansions or contractions of a few thousandths of 1 percent, as found for four of the

five samples tested, probably have no practical

significance. The comparatively large changes

found, for aggregate 43 (0.03 to 0.04 percent)

might be regarded at least as a contributory cause of cracking. When dry chips are incorporated in a mixture, they will absorb water,

and expansions will occiu* over a period of several hours. Some of the expansion will evidently take place after the cement has

undergone the initial stages of hardening. If the mixture is properly cured, one may expect

the aggregate to remain in an expanded condition for sev eral days. Shrinkage of the aggregate will probably not begin for a few days

after sprinkling of the surface has been discontinued. Thereafter, shrinkage of the aggregate

will occur simultaneously with shrinkage of the

cement paste.

Several small slabs of terrazzo, cut transversely, have been examined to determine if the

effects of shrinkage of the aggr(>gate and

cement paste were in evidence. Very few in- stances of separation of aggregate and paste were noted except where rather long cracks

occurred. Few such cracks were noted in the

small slabs, and in these the cracks sometimes

followed the boundaries of chips, and other

times, passed through the chips. One sample

of terrazzo taken from a monolithic floor showed

a network of cracks, and the greatest length of uncracked surface observed was about 8 in. This seems to indicate that shi'inkage in terrazzo tends to draw the material in small sections

toward tlie centers of the sections, causing

tensile stresses between these centers, which

may exceed the tensile strength of the aggregate

or cement paste. All the samples examined showed frequent

air pockets which were roughly spherical in shape and varying in diameter from 0.004 to 0.25 m. In several samples there were also numerous voids resembling short cracks in the

cement paste. The average length of these was about 0.2 in., and the width varied from

0.004 to 0.02 in. The pecuhar shapes of these

voids indicate that they were neither air pockets nor cracks, and if they resulted from

shrinkage, they were probably formed before

the mixture had hardened.

(b) Temperature Effects. Three determinations of thermal expansion were made on sample 54, the aggregate which is claimed to give trouble in terrazzo installations.

For each determination the specimens were cut

in different directions to give the expansion in three directions at right angles to each other.

The expansion curves in figure 6 show that the

expansion rates in the directions measured differ considerably and vary for different temperature ranges. All show hysteresis effects and

inflection points on the heating cm'ves between

0° and 11° C. The highest coefficient of ex- pansion (0.0000087) was indicated for direction

A in cooling the specimen from 60° to 0° C.

and negative expansion was found for the direction Cm heating the specimen from 7° to 20° C. No inflection points occuiTed on the cooling

[17]
I

i

Curi/t? foreiireci ion 3

-I

Curvt' for ci/recf/onC

-30 -20 -10 0 10 ZO 30 40

Tempercrfure, ° C

50 60 70

Figure 6.—Thermal-expansion curves for a calcite (sample 54) for three directions at right angles to each

other

curves, and the expansion rates gradually

decreased as the temperatures were lowered.

The sample was a calcite marble, and calcite

crystals are known to have a positive coefficient

of expansion in the direction of the principal

axis and a negative coefficient perpendicular to

tliat axis. The different expansion values obtained on sample 54 for different directions may

possibly have been caused by a preponderance

of its crystals being alined in the direction

designated A. The effects of such differential

expansion of an aggregate on the performance

of terrazzo have not been determined. Differ- ences between the coefficients of expansion of

the aggregate and cement paste have been cited

as a cause of disintegration in concrete,^* and

aggregates having marked differences in expansions for dift'erent directions liave been regarded

" J. C. Pearson. A Concrete Failure Attributed to Aggregate of Low- Thermal Coefflcient. J. Am. Concrete Inst. 13 No. 1 (September 1941, and Discussion Vol. IG, No. 6 (June 1942).

as detrimental, but there is considerable doubt

as to whether such aggregates in terrazzo would

cause trouble because of the comparatively

small temperature range inside of buildings.

V. SUMMARY

Seventy-seven samples of terrazzo aggregate were supplied by 24 producers from deposits

in 12 States and 1 foreign country. The samples were classified as to mineral composition,

and descriptive terms for color, texture, and

structure are given. The color terms were

derived by the method recommended by the

Inter-Society Color Council. These designations often differ from the trade color designations, so the latter are also stated. The tests for comparative data on the rock in its original

condition included wear resistance, absorption,

bulk specific gravity, and toughness. Tests on

No. 2 chips were made to determine the dust

content and percentage of voids in the aggregate

in the "loose" and "vibrated" states. Certain

aggi'egate samples in the series, including some

which have been reported to give unsatisfactory

results in terrazzo mixtures, have been subjected

to additional tests, such as thermal and moisture expansion.

The abrasive-resistance values (Ha) for the

samples range from 8.9 to 112.2 and average

30. Aggregates having Ha values of 18 or higher are considered to be suitable for the

most severe conditions of foot traffic. The bulk specific gravity values range from

2.20 to 2.98, corresponding to weights of 137

to 186 Ib/ft^ of the original rock, respectively.

Unit weights of No. 2 aggregate (not compacted)

have a range from 82 to 105 Ib/ft^

Absorption values range from 0.03 to 7.43

percent and average 0.67 percent.

Toughness values (impact resistance) range

from 3 to 24. Aggregates having low toughness values show a tendency to abrade and

form dust in the shipping containers.

The dust content of the samples varied from

0.09 to 2.08 percent and averaged 0.57 percent.

The average amount of voids in No. 2 chips,

not compacted in the measure, was 44.7 per- cent and wlien compacted, 41.2 percent. The

[18]
range for all the samples when compacted was

from 36.5 to 50.1 percent. Tests on a few 1:1 mixtures of No. 1 and No. 2 chips gave void

contents about 2 percent lower than for No. 2 chips alone. For most aggregates the com- monly used proportions (1 part of cement to 2 parts of aggregate) provide considerably more

cement paste than is required to fill the voids

in the aggregate.

The shapes of chips made fi'om different rocks

vary considerably. Some varieties yield fragments approximating spheres, whereas others

yield a large portion of flat chips. Flat particles near the surface of terrazzo mixtures are usually turned to a horizontal position during

the rolling process and probably interfere with

the removal of excess cement paste from the

mixture. A test was devised to grade the

various samples of No. 2 aggregate into four

parts, based on the least diameter of particles.

A comparison of the graphs illustrating the

distribution of thickness grades in various aggregates shows marked differences in the shapes of

these curves for dift'erent aggi'egates. Four

varieties of chips which have been rated high

in performance by terrazzo workmen, show a

fairly uniform increase in amounts from thin to thick particles. Two aggregates reported to give trouble showed large decreases in the

amounts of thickest particles from that in the

next thuiner grade.

Five samples tested for moisture expansion

showed a large range in values. One sample

expanded nearly 0.04 percent while soaking, an amount about equal to that of a 70° C

increase in temperature. None of the others

expanded more than that which would result

from a 12° C increase in temperature. Contractions of the material while drying were approximately the same as the expansions while

soaking.

One sample tested for thermal expansion in three directions at right angles to each other

indicated that the material expands at dift'erent rates in these directions and that the rates are

vai-iable over dift'erent temperature ranges. In one direction the specimen contracted as the

temperature increased from 7° to 20° C and

expanded at higher temperatures. Contractions caused by temperature drops are probably

not sufficient to account for the cracking of terrazzo.

The authors express their appreciation to the producers for their cooperation in supplying

samples, to D. B. Judd in determining the

proper color designations; and to Herbert

Insley for microscopic studies in cormection

with classifying the materials.

Washington, December 14, 1942.

[19]

1

BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page ii] BMS32 Structural Properties of Two Brick-Concrete-Block Wall Constructions and a Concrete- Block Wall Construction Sponsored by the National Concrete Masonry Association. . 10^ BMS33 Plastic Calking Materials 10^ BMS34 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 1 10^ BMS35 Stability of Sheathing Papers as Determined by Accelerated Aging 10^ 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^ BMS37 Structural Properties of "Palisade Homes" Constructions for Walls, Partitions, and

Floors, Sponsored by Palisade Homes 10^ BMS38 Structural Properties of Two "Dunstone" Wall Constructions Sponsored by the W. E. Dunn Manufacturing Co lOjS BMS39 Structural Properties of a WaU 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 10^ BMS41 Efifect of Heating and Cooling on the Permeability of Masonry Walls 10^ BMS42 Structural Properties of Wood-Frame Wail and Partition Constructions with "Celotex"

Insulating Boards Sponsored by The Celotex Corporation 15^ BMS43 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 2 10^ BMS44 Surface Treatment of Steel Prior to Painting 10^ BMS45 Air Infiltration Through Windows 10^ BMS46 Structural Properties of "Scot-BUt" Prefabricated Sheet-Steel Constructions for Walls,

Floors, and Roofs Sponsored by The Globe-Wernicke Co 10^ BMS47 Structural Properties of Prefabricated Wood-Frame Constructions for Walls, Partitions,

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

Sponsored by the Homasote Co 10^ BMS49 Metallic Roofing for Low-Cost House Construction 10^ BMS50 Stability of Fiber Building Boards as Determined by Accelerated Aging 10^ BMS51 Structural Properties of "Tilecrete Type A" Floor Construction Sponsored by the

Tilecrete Co 10^ BMS52 Efifect of Ceiling Insulation Upon Summer Comfort 10^ BMS53 Structural Properties of a Masonry Wall Construction of "Munlock Dry Wall Brick"

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

Bricks Produced in the United States 15^ 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 10^ BMS63 Moisture Condensation in Building Walls 10^ BMS64 Solar Heating of Various Surfaces 10^ BMS65 Methods of Estimating Loads in Plumbing Systems 10^ BMS66 Plumbing Manual 20^ 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 15^ BMS69 Stability of Fiber Sheathing Boards as Determined by Accelerated Aging 10^ BMS70 Asphalt-Prepared Roll Roofings and Shingles 15^ 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 10^ BMS74 Structural and Heat-Transfer Properties of "U. S. S. Panelbilt" Prefabricated SheetSteel Constructions for Walls, Partitions, and Roofs Sponsored by the Tennessee

Coal, Iron & Railroiad Co 15j5 BMS75 Survey of Roofing Materials in the North Cenral States 15^ BMS76 Effect of Outdoor Exposure on the Water Permeability of Masonry Walls 15^ BMS77 Properties and Performance of Fiber Tile Boards 10^ BMS78 Structural, Heat-Transfer, and Water-Permeability Properties of Five Earth-Wall

Constructions 20^ BMS79 Water-Distributing Systems for Buildings 156 BMS80 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 4 15^ BMS81 Field Inspectors' Check List for Building Construction (cloth cover, 5 x 7K inches) 20^ BMS82 Water Permeability of Walls Built of Masonry Units 20<S [List continued on cover page iv]
BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page iii] BMS83 Strength of Sleeve Joints in Copper Tubing Made With Various Lead-Base Solders lOjl 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 15^ BMS87 A Method for Developing Specifications for Building Construction 10^ BMS88 Recommended Building Code Requirements for New Dwelling Construction with Special Reference to War Housing 20^ BMS89 Structural Properties of "Precision-Built, Jr." (Second Construction) Prefabricated Wood-Frame Wall Construction Sponsored by the Homasote Co 15j5 BMS90 Structural Properties of "PHC" Prefabricated Wood-Frame Constructions for Walls,

Floors, and Roofs Sponsored by the PHC Housing Corporation 15^ BMS91 A Glossary of Housing Terms 15^ BMS92 Fire-Resistance Classifications of Building Constructions 25j! BMS93 Accumulation 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 10^ BMS95 Tests of Cement-Water Paints and Other Waterproofings for Unit-Masonry Walls 15^ BMS96 Properties of a Porous Concrete of Cement and Uniform-Sized Gravel lOji BMS97 Experimental Dry-Wall Construction with Fiber Insulating Board lOjS BMS98 Physical Properties of Terrazzo Aggregates 150