Ijireau

nCT

of Stanaarusi

4 1939
The program of research on building materials and structures, carried on by the

National Bureau of Standards, was undertaken with the assistance of the Central

Housing Committee, an informal organization of Government agencies concerned

with housing construction and finance, which is cooperating in the investigations through

a subcommittee of principal technical assistants.

CENTRAL HOUSING COMMITTEE

SUBCOMMITTEE ON TECHNICAL RESEARCH

Walter Junge, Chairman. Arthur C. Shire, Vice Chairman.

Federal Housing Administration. United States Housing Authority.

Sterling R. March, Secretary

Albert G. Bear,

Veterans' Administration.

Pierre Blouke,

Federal Home Loan Bank Board.

Carroll W. Chamberlain,

Procxu-ement Division (Treasury).

Joseph M. DallaValle,

Public Health Service.

John Donovan,

Farm Security Administration (Agriculture).

George E. Knox,

Yards and Docks (Navy).

Vincent B. Phelan,

National Bureau of Standards (Commerce).

Edward A. Poynton,

Office of Indian Affairs (Interior).

George W. Trayer,

Forest Service (Agriculture).

Elsmere J. Walters,

Construction Division (War).

CHAIRMEN OF SECTIONS

Specifications Materials Maintenance

Carroll W. Chamberlain Elsmere J. Walters John H. Schaefer

Mechanical Equipment Methods and Practices

Robert K. Thulman

NATIONAL BUREAU OF STANDARDS

STAFF COMMITTEE ON ADMINISTRATION AND COORDINATION

Hugh L. Dryden, Chairman.

Mechanics and Sound

Phaon H. Bates, Gustav E. F. Lundell,

Clay and SUicate Products. Chemistry.

HoBART C, Dickinson, Addams S. McAllister,

Heat and Power. Codes and Specifications.

Warren E. Emley, Henry S. Rawdon,

Organic and Fibrous Materials. Metallurgy.

The Forest Products Laboratory of the United States Department of Agriculture

is cooperating with both committees on investigations of wood constructions.

[For list of BMS publications and how to purchase, see cover page III.]
UNITED STATES DEPARTMENT OF COMMERCE • Harry E. Hopkins, Secretary

NATIONAL BUREAU OF STANDARDS • Lyman J. Briggs, Director

BUILDING MATERIALS

and STRUCTURES

REPORT BMS24

Structural Properties oi a Reinforced-Brick Wall Construction

and a Brick-Tile Cavity-Wall Construction

I Sponsored by the Structural Clay Products Institute

by HERBERT L. WHITTEMORE, AMBROSE H. STANG,

and CYRUS c. fishburn

ISSUED AUGUST 24, 1939

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

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

UNITED STATES GOVERNMENT PRINTING OFFICE • WASHINGTON • 1939

FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, WASHINGTON, D. C. • PRICE lO CENTS
Foreword

This report is one of a series issued by the National Bureau of Standards on the structural properties of constructions intended for low-cost houses and apartments. Practically all of these constructions were sponsored by groups within the building industry

which advocate and promote the use of such constructions and which have built and

submitted representative specimens as outlined in report BMS2, Methods of Determining

the Structural Properties of Low-Cost House Constructions. The sponsor is responsible

for the representative character of the specimens and for the description given in each

report. The Bureau is responsible for the test data.

This report covers only the load-deformation relations and strength of the walls of a house when subjected to compressive, transverse, concentrated, impact, and racking

loads by standardized methods simulating the loads to which the walls would be subjected in actual service. It may be feasible later to determine the heat transmission at ordinary temperatures and the fire resistance of these constructions and perhaps other

properties.

The National Bureau of Standards does not "approve" a construction, nor does it express an opinion as to the merits of a construction, for the reasons given in reports

BMSl and BMS2. The technical facts on these and other constructions provide the

basic data from which architects and engineers can determine whether a construction

meets desired performance requirements.

Lyman J. Briggs, Director.

in]
Structural Properties of a Reinforced-Brick Wall Construction and

a Brick-Tile Cavity-Wall Construction Sponsored by

the Structural Clay Products Institute

by HERBERT L. WHITTEMORE, AMBROSE H. STANG, and ('YRUS C. FISHBLTRN

CONTENTS

Page

Foreword n

I. Introduction 1

II. Sponsor and product 2

III. Specimens and tests 2

IV. Wall AT. 3

1. Sponsor's statement 3

(a) Materials 3

(b) Description 4

(c) Fabrication data 4

(d) Comments 4

2. Compressive load 5

3. Transverse load 5

4. Concentrated load 6

5. Impact load 6

VI.

Page

Wall AU 6

1. Sponsor's statement 6

(a) Materials 6

(b) Description 9

(1) Four-foot wall speci- mens 9

(2) Eif<ht-foot. wall speci- mens 9

(c) Fabrication data 9

(d) Comments 9

2. Compressive load 10

3. Transverse load 10

4. Concentrated load 11

5. Impact load 11

6. Racking load 15 Selected references 17

1. Reinforced brick masonry 17

2. Cavity (hollow) walls 17

ABSTRACT

For the program on the determination of the structural properties of low-cost house constructions, the

i Structural Clay Products Institute submitted 9 speci-

; mens representing a reinforced-brick wall construction

J and 18 specimens representing a brick-tile cavity-wall

i| construction.

I The reinforced-brick wall specimens were subjected

j to compressive, transverse, concentrated, and impact

jl loads. The brick-tile cavity-wall specimens were subII jected to compressive, transverse, concentrated, impact, and racking loads. The transverse, concentrated, and

impact loads were applied to both faces of the brickil tile cavity-wall specimens. For each of these loads

three like specimens were tested. The deformation

under load and the set after the load was removed were measured for uniform increments of load, except for concentrated loads, for which the set only was de- termined. The results are presented graphically and

in tables.

I. INTRODUCTION

In order to provide technical facts on the per- formance of constructions which might be used

in low-cost houses, to discover promising constructions, and ultimately to determine the

properties necessary for acceptable performance,

the National Bureau of Standards has invited

the building industry to cooperate in a program

of research on building materials and structures

for use in low-cost houses and apartments. The

objectives of this program are described in re- port BMSl, Research on Building Materials

and Structures for Use in Low-Cost Housing,

and that part of the program relating to struc- tural properties in report BMS2, Methods of Determining the Structural Properties of LowCost House Constructions.

As a part of the research on structural properties, six masonry wall constructions have been

subjected to a series of standardized laboratory

tests to provide data on the properties of some

constructions for which the behavior in service

is generally known. These data are given in

report BMS5, Structural Properties of Six

Masonry Wall Constructions. Similar tests have been made on wood-frame constructions

by the Forest Products Laboratory of the

1]
United States Department of Agriculture, the

results of which will be given in a subsequent

report in this series. The present report describes the structural

properties of two wall constructions sponsored

by one of the groups in the building industry.

The specimens were subjected to compressive,

transverse, concentrated, impact, and racking

loads, simulating loads to which the elements of a house are subjected. In actual service, compressive loads on a wall are produced by the

weight of the roof, second floor and secondstory walls, if any, furniture and occupants,

wind load on adjoining second-story walls, and snow and wind loads on the roof. Transverse

loads on a wall are produced by the wind, con- centrated and impact loads by furniture or accidental contact with heavy objects, and racking loads by the action of the wind on adjoining

walls. The deformation and set under each increment of load were measured because the suit- ability of a wall construction depends in part on its resistance to deformation imder load and

whether it returns to its original size and shape

when the load is removed.

II. SPONSOR AND PRODUCT

The specimens were submitted by the Structural Clay Products Institute, Washington,

D. C, and represented a reinforced and grouted

brick wall construction designed to resist trans- verse loads, such as those caused by high winds

and earthquakes, and a brick-tile cavity-wall

construction which has been used extensively

in Europe.

The remforced-brick wall specimens were

built with a brick facing and backing connected

(bonded) by steel wall ties, and reinforced by

steel bars set in grout in the vertical collar joint

between the facing and backing. The bed

joints and the outside of the head joints were cement mortar. The collar joint and the inside

of the head joints were filled with grout.

The brick-tile cavity-wall specimens were

built with a brick facing and a structural claytile backing separated by an air space and con- nected by steel wall ties. The joints were

cement-lime mortar.

III. SPECIMENS AND TESTS

The reinforced-brick woll construction was

assigned the symbol AT, and the brick-tile

cavity wall was assigned the symbol AU. The

specimens were assigned the designations given

in table 1.Table 1.

Specimen designations

Element

Construc- tion symbol

Specimen

designation Load Load applied

Wall AT CI, Ct, CS..- Compressive- Upper end. Do AT Tl, T2, TS . Transverse-- - Either face. Do AT PI, P2, PS • Concentrated

Do. Do AT //, 12. IS Impact Do. Do AU CI, C2, CS.. Compressive.- Upper end. Do AV Tl, T2. TS.- Transverse Inside face. Do AV Ti, T5, r«__ do Outside face. Do AU P1,P2,P3^. Concentrated. Inside face. Do AU Pi,PS,P6'. do Outside face. Do AU 11, 12, IS Impact.. Inside face. Do AU

AU U, 15, 16 do Outside face. Do_ _ Rl. R2. RS.. Racking. . Near upper end.

" These specimens were undamaged portions of the transverse speci- mens.No racking specimens were built for the reinforced-brick wall AT because for the 8-in. brick walls AA, AB, and AC, reported in BMS5, Structural Properties of Six Masonry

Wall Constructions, none of the specimens

failed under a racking load of 50 kips, the

capacity of the racking equipment, and the

deformations and sets for this load were very

small. The compressive, transverse, and impact strengths of wall AT were greater than

those of walls AB and AC, and it is probable

that the racking strength also would have been

greater.

The specimens were tested in accordance

with BMS2, Methods of Determining the

Structural Properties of Low-Cost House Constructions, which also gives the requirements

for the specimens and describes the presentation of the results of the tests, particularly the

load-deformation graphs.

For the transverse, concentrated, and impact loads, only three specimens of the reinforced-brick wall construction were tested be- cause the wall was symmetrical about a plane

midway between the faces, and the results for loads applied to one face of the specimens

should be the same as those obtained by

applying the loads to the other face. The tests were begun on March 28, 19.S8,

and completed July 8, 1938. The specimens

[2]
were tested 28 days after they were built. The sponsor's representative witnessed the

tests. IV. WALL AT

I. Sponsor's Statement

(a) Materials

Brick. —Side-cut clay brick manufactured in

Baltimore and furnished by the Baltimore

Brick Co. through the Hydraulic Press Brick

Co., Washington, D. C. The average dimensions were 8.02 by 3.85 by 2.29 in. (about 8 by

32^2 by 2%2 in).

The physical properties of the brick, determined by the Masonry Construction Section of the National Bureau of Standards, are given in

table 2. The brick complied with grade SW

of the American Society for Testing Materials

Tentative Standard C 62-37T.

Table 2.

Physical proprrtics of the brick

Water absorption

Compressive strength

Modulus of rupture 5-hr cold

24-hr

cold, C

,5-hr boil, B

Saturation coefficient, CB

1-min

partial immersion,"

as laid

Weight,

dry

lb/in.'' 5,160

Ib/inJ 830 %

9.5 %10.2 %14. 7 0. 69

g/brick19Ib/hrick

4. 76

» Immersed on flat side in in. of water.

Mortar.—The materials for the mortar were Medusa Cement Co.'s "Medusa" portland

cement, lime putty made by slaking Standard

Lime and Stone Co.'s "Washington" powdered

quicklime, and Potomac River building sand.

The mortar was 1 part of portland cement,

0.11 part of hydrated lime, and 2.6 parts of dry

sand, by weight. The proportions by volume

were 1 part of cement, 0.25 part of hydrated

lime, and 3 parts of loose damp sand, assuming

that portland cement weighs 94 Ib/ft^, dry

hydrated lime 40 Ib/ft^, and 80 lb of dry sand

are equivalent to 1 ft^ of loose damp sand.

The materials for each batch were measured by

weight and mixed in a batch mixer having a capacity of 2/3 ft^. The amount of water

added to the mortar was adjusted to the satis- faction of the mason. The following properties of the mortar materials and the mortar were determined by the

Masonry Construction Section. The cement

complied witli the requinjments of Federal

Specification SS-C-19]a for fineness, soundness,

time of setting, and tensile strength. The lime

putty contained about 40 percent of dry l)ydrate, by weight, and had a plasticity of over

600 measui-ed in accordance with Federal

Specification SS-L-351. The sieve analysis of

tlie sand is given in table 3.

Table 3.

Siem analy.si.i of the. Hand

U. S. standard Passins,

sieve number by weight

Percent

8 100

16 96

30 82

50 24 inn 2

The average water content of the mortar was

19.8 percent, by weight of dry materials.

Samples were taken from at least one batch of mortar for each wall specimen, the flow determined in accordance with Federal Specification

SS-C-181b, and six 2-in. cubes made. Three

cubes were stored in water at 70° F and three

stored in air near each specimen. The compressive strength of each cube was determined on the day the corresponding wall specimen was

tested. The physical properties of the mortar

are given in table 4.

Table 4.

Physical properties of mortar, wall AT

Specimen

CIC2OS

TlT2

TS

//

12n

.^verai

Flow

Percent

126

138 135

139 132

132

123

127

131 126

126

124

123

119 130

130 128

129

Compressive strength

Air storage

lb/in.'

1, 540 1,660 1,720

1,530

1,700 1,670

1,820

1,740

1,600

1,780

1,910

1,650

1, 510 1,690

1,540

1,620

1,800

1,

Water

storage

lb/in.'

3, 780 3,810

3, 620

3. 680 3,310

3,440

3, 760

3, 650 3,660

3,910

3, 750

3, 720

3. 030 3.660

3,550

3, 760

3, 800

3.640

Grout.—The grout was 1 part of cement,

0.062 part of hydrated lime, 1.45 parts of dry

sand, and 0.63 part of water, by weight.

[3]
Ties.—Steel, K-in. diam, bent to a Z-shape

with 90° angles between the outstanding legs

and the stem. The length of the stem was

6 in. and of the outstanding legs 3 in. Reinforcement bars.—Deformed, billet steel,

Ys in. diam; yield point, 53,200 lb/in. ^; tensile strength, 78,400 Ib/in.^; weight, 0.375 lb /ft.

(6) Description

The wall specimens had either 35 or 36

courses of briclc. The average height was

8 ft 2 in. for specimens with 35 courses and

8 ft 5 in. for specimens with 36 courses. The

width was 4 ft 2)^ in. and the thickness 8}^ in. The wall was reinforced with two vertical reinforcement bars. A, shown in figure 1, and five horizontal reinforcement bars, B. The horizontal bars were spaced eight courses apart, the

first bar being between the second and third

Figure 1.

Four-foot wall specimen AT, having 35

courses.

A, vertical reinforcement bars; B, horizontal reinforcement bars; C, wall

ties.

course. In addition, four wall ties, C, were

placed every fifth course. The ties were spaced

1 ft on centers. The building of each specimen was begun by

laying five stretcher courses of the facing. The

bed joints were level, and the head joints were

buttered on the outside face, leaving the greater

portion of these joints open. The first course

of the backing was then laid with the same kind

of joints as was used in the facing. The collar

joint, 1 in. wide, was left open except for a plug

of mortar at each end. The vertical reinforcement was supported in position, using a temporary wood support at the top of the bars. The collar joint and the open portions of the

head joints in both faces were then filled with

grout to the level of the top of the brick in the

backing. This operation was then repeated

course by course until five courses of the backing were laid. The wall ties, C, were then

placed in the wall and the next five courses of the facing were laid. The bed joints were level and were completely

filled with mortar. The head joints were filled partly with mortar and partly with grout.

The collar joints were completely filled with

grout. The joints were cut flush with the faces

of the specimen.

The price of this construction in Washington,

D. C, as of July 1937 was $0.50/ftl

(c) Fabrication Data

The fabrication data, determined by the

Masonry Construction Section, are given in table 5.Table 5.

Fabrication data, wall AT

[The values per square foot were computed using the face area of the specimens]

Thickness of joints Masonry

units

Mortar materials Mason's

Bed Head Cement Lime, dry

hydrate

Sand, dry

time

in.

0. 52

in.

0. 51 No.IP12. 2 Iblff9.2

Iblff1.0

IblfP 23.9 hrip

0. 16

id) Comments

Reinforced-brick masonry is used for retaining walls and foundations, and also for walls

above grade subjected to high winds and earthquakes. When used as a facing for large con-

[4]
Crete structures, such as dams, retaining walls,

etc., it may be used as part of the formwork for the concrete. The horizontal reinforcement bars in spandrel

walls (above and below window and door openings) are bent and lapped at the corners to make

the building act as a unit under load. The

vertical joints between the backing and facing

are filled with grout or mortar. Grout-filled

walls are strongly preferred because they offer more resistance to moisture penetration.

The outside of foundation walls should })c

waterproofed under all conditions where waterproofing is recommended for other types of foundation walls. However, for grout-filled

walls, flashings around openings may be omitted.

The outside mortar joints should be concave,

tooled with a round jointing tool to compress

firmly the mortar against the brick. The inside

face may be used without decoration or may be

finished with paint or plaster applied directly

to the brick.

2. Compressive Load

Wall specimen AT-C3 under compressive

load is shown in figure 2. The results for wall

specimens AT-Cl , C2, and CS are shown in table 6 and in figures 3 and 4.

Table 6.

Structural pi-operties, wall AT

[Weight, 88.7 lb/ft']

Load Loail applied

Speci- men

desig- nation

Maximum

height

of drop

Maxi- mum

load

Compressive

Transverse

rUpper end, 2.83 in. from

\ the inside face.

Average

I CI

{ Ci

\ CS

ft 'kipKlfl 154 142

191

l')2

One face; span, 7 ft 6 in..

Average

I Tl

\ Tt

\ TS

Ib/fP218

184 206

Concentrated _ .

.

Impact

203

One face \ P2

\ PS

b 1, 000

b 1,000

b 1, 000 Average . ... b 1, 000

One face; span 7 ft fi in.._

Average

\ 12

[ IS

!> 10.0

b 10.0

b 10.0

b 10, 0

« A kip is 1.0001b.

b Specimen did not fail. Test discontinued.

Figure 2. —Wall specimen AT-C3 under compressive

load

The compressive loads were applied 2.83 in. from the inside face. The shortenings and

sets shown in figure 3 for a height of 8 ft were computed from the values obtained from the

compressometer readings. The gage length of the compressometers was 7 ft 3 in. Specimens Cl and C2 failed by rupture of the collar joints at both edges of the specunens

and crushing of bricks in several courses on the

inside face. For specimen CS the lower third

of the specimen completely collapsed.

3. Transverse Load

The results for wall specimens AT Tl , T2,

and TS are shown in table 6 and in figure 5.

[5]
0 0.04 0.08 0.12

Figure 3.

Compressive load on wall AT.

Load-shortening (open circles) and load-set (solid circles) results for spec- imens AT-Cl, C2, and CS. The load was applied 2.83 in. from the

inside face. The loads are in kips per foot of actual width of specimen.

At loads of 190, 142, and 166 Ib/ft^ for specimens Tl, T2, and T3, respectively, the

bond between the brick and the mortar ruptured at one or more bed joints between the

loading rollers. At the maximum loads these

cracks opened further and new cracks developed. Each of the specimens failed by deflect- ing continuously under constant load.

4. Concentrated Load

Wall specimen AT-P2 under concentrated

load is shown in figure 6. The results for wall

specimens AT-Pl, P2, and PS are shown in table 6 and in figure 7. The indentations after a load of 1,000 lb had been applied were 0.006, 0.002, and 0.002

in. for specimens Pi, P2, and PS, respectively,

and no other effect was observed.

5. Impact Load

The results for wall specimens AT-Il, 12,

and IS are shown in table 6 and in figure 8.

The set after a drop of 10 ft was 0.020 in. for specimen II, and there was a crack about

2 in. long between a brick and the mortar at one edge of the specimen in a bed joint near midspan. The sets after a drop of 10 ft were

0.007 and 0.015 in. for specimens 12 and IS,

respectively, and no other effect was observed.

V. WALL AU

1. Sponsor's Statement

(a) Materials

Brick.—The brick were the same as for wall

AT. The water absorption for 1-min partial

immersion, as laid, was 19 grams/brick.

Tile.—The structural clay tile were obtained

from the National Fireproofing Company and were made in Magnolia, Ohio. The tile had

four cells, as shown in figure 9. The average

dimensions were 3.76 by 4.95 by 11.95 in. (about

3% by 41^(6 by 12 in).

0 0.2 0.4. 0.6

/afera/ def/echon in. Figure 4.

Compressive load on wall AT.

Load-lateral deflection (open circles) and load-lateral set (solid circles) results for specimens AT-Cl, C2, and CS. The load was applied 2.83

in. from the inside face. The loads are in kips per foot of actual width

of specimen. The deflections and sets are for a gage length of 7 ft 3 in., the gage length of the deflectometers.

[6]
240

^200

160

0)

40,

0

m•-•

-L-j

o • c cr<O—

O

) o

AT 0 0.2 0.4 0.6

deflecfion in. Figure 5.—Transverse load on loall A7\

Load-deflection (open circles) and load-set (solid circles) results for speci- mens AT-Tl, T2, and TS on the span 7 ft 6 in.

The physical proportios of the tile, deterniiiiPfl by tlie Masoiiiy C'oTistnictioii Section,

ai'c liivcii in table 7.

Table 7.

Physical /jroperiits of the tile, -wall A U

Thickness

of face

shell, minininiTi

liatio of width of

cell to over-all

Compressive

stronRth, load applied to side Water absorption Weight, dry thickness

of hearing

shell Not area dross area

24-hr cold

l-hr)ioil

in.

0. 40 2. 1

Ihlvn.i

4, Olll 1, 720 Percevl4. (1 Percent

r,. II

Ibltile

U. W

The tile coiuplied with the American Society

for Testing Materials Standard C 34-36, except

for the water absorption determined by the 1-hr

boil test. The average value of 5.9 percent

complied with the Standard, but the hldi^•idual

values for four of the ten specimens were less than the specified minimum value of 4 percent.

These values were 2.9, 2.9, 3.0, and 3.6 percent.

Mortar.—The materials for the mortar were

the same as for wall AT.

The mortar was 1 part of cement, 0.42 part

of hydrated lime, and 5.1 parts of dry sand,
5p

I L

1 (»-•-

1 <»-•—

1 (-•-

1 <^«—

1 o

1 «

1 •

1•

0 0.02 0.04 0.06

indenfafion in.

FiGiTiiE 7.

Concentrated load on wall AT.

Load-indenlatinn results for specimens AT-Pl. P2, and PS.

10

8

^ 6

y-jior AT 0 0.2 0.4 o.e deflecfion in. Figure S.—Impad load on wall AT.

Height of drop-deflection (open circles) and height of drop-set (solid

circles) results for specimens AT-11 , 12, and IS on the span 7 ft 0 in.

Figure 9.

Structural clay tile.

by weight. The proportions by vohime were

1 part of cement, 1 part of hydrated Hme, and

6 parts of loose damp sand, assuming that portland cement weighs 94 Ib/ft^, dry hydrated

lime 40 Ib/ft^, and 80 lb of dry sand is equivalent to 1 ft^ of loose damp sand. The

materials for each batch were measured by

weight and mixed in a batch mixer having a capacity of 2/3 ft^ The amount of water

added to the mortar was adjusted to the satis- faction of the mason.

Table 8.Physical properties of mortar, wall AU

Specimen

CI«...

CS

TlT2

TSnr.5 ren

ISU

u.

IS... RlmRSA verage

Compressive strength Flow

Air storage Water

storage

Percent

j 118

\ 115

116

116

362

361 417

388

Iblin.i 656 636

647 685

119

118 382307

687

597

120

121 114

112

280

398

360

379

658

675

654 620

112

111 110 108

111

113

r no

1 112

81 109

466

450 356

533

371 604

528 452

421 469

676

663

651 663

631

607 596

591 685 722

112 414 650

The physical properties of the mortar were

determined by the Masonry Construction

Section. The average water content of the

mortar was 23.2 percent, by weight of dry

materials. Samples were taken from at least one batch of mortar for each wall specimen, the

[8]
flow determined in accordance with Federal

Specification SS-C-181b, and six 2-in. cubes

made. Three cubes were stored in water at 70° F and three stored in air near each speci- men. The compressive strength of each cube was determined on the day the corresponding

wall specimen was tested. The physical properties of the mortar are given in table 8. Ties. —Steel, }{-in. diam, bent to a Z-shape

with 90° angles between the outstanding legs

and the stems. The length of the stem was

fi in. and of the outstanding legs, 3 in.

ih) Description

(1) Four-foot wall S2)ecimens.— -The 4-ft wall

specimens were 8 ft 3 in. high, 4 ft 1 in. wide,

and 9% in. thick. The specimens were built

with a brick facnig, A, as shown in figure 10,

and a structural clay-tile backing, B, separated

by an air space, C, and connected by wall ties, D. There were 36 courses of brick and 18 courses of tile. The ties were placed every

sixth brick course starting with the fourth

course from the lower end. The ties were

spaced as shown in the figure, at least K in. from the nearest head joint.

The bed joints under both the brick and the

tile were furrowed. The head joints of the

brick were completely filled with mortar by

hea\dly buttering the end of each brick before

placing. Wlien necessary, additional mortar was slushed into the joint from above. The

head joints in the tile were made by buttering

the outside edges of the tile, leaving the inside

of the cross joint open. The nominal thickness

of the joints was ^4 in., and the joints were

cut flush with the faces of the masonry units.

The price of this construction in Washington,

D. C, as of July 1937 was $0.50/ftl

(2) Eight-foot wall specimens.—The 8-ft wall

specimens were 8 ft 3 in. high, 8 ft 3 in. wide,

and 9% in. thick. The specimens were similar

to the 4-ft specimens. There were four wall

ties, spaced 2 ft 0 in. on centers, in every sixth

brick course starting with the fourth course from the lower end.

(c) Fabrication Data

The fabrication data, determined by the

Masonry Construction Section, are given in table 9.

Figure 10.

Four-foot wall specimen AU.

A, facing; B, backing; C, air space; D, wall ties. Table 9.

Fabrication data, wall AU

[The values per square foot were computed using the face urea nf the specimens]

Thickness of joints Mortar materials

Bed Head

Masonry

units Ce- ment

Lime,

dry

hydrate

Sand, dry

Mason's time

in.

0. 46(brick~i. .56 (tile)..

in.

0. 58 (brick).

.3!) (tile) ..

No.lft'

6. 1 (brick).

2. 1 (tile) . } 2.0 0.8

Ibljf 10 2hr/fP

0. 15

{(1) Comments

Cavity walls with brick ties have been used in

this country for at least 50 years in all types of buildings. In the last 20 years many buildings

have been erected with All-Rolok and RolokBak walls, two types of cavity walls with brick

ties.Cavity walls with metal ties have been used

in England for several decades; and almost all the masonry structures built during the past

15 years have been of this type. This construction was introduced into the United States many

[9]
years ago, and the number of buildings built

with cavity walls has increased greatly during

the past 5 years. About 300 houses of this construction were built in 1938. In a house, the cavity wall extends from the

top of the foundation wall to the eaves or to the

base of the parapet wall. The bottom of the

cavity should be below the damp-proofed course.

FiGXfRE 11.

Lintel flasliijig and damp clieck for cavity

wullf!.

A, flashing; B, wall ties; C, damp check; and Z>, weep hole.

but above ground level. Weep holes should be

provided at intervals in the head joints in the

facing at the bottom of the cavity. These holes

should slope down from the bottom of the

cavity to the outside of the wall. The cavity may be either closed (except for weep holes) or ventilated. If closed, the upper

and lower ends are sealed. If ventilated, the

entire wall or only the upper or lower portiou

may be ventilated. The closed cavity has

better thermal insulation, while the ventilated

cavity will allow moisture to evaporate more

quickly, if any penetrates the facing.

Flashings, extending at least 6 in. beyond the

jambs, must be used over all openings for doors

and windows, as shown in figure 11. Parapet

walls used above cavity walls should have watertight copings and should be adequately flashed. Cavity walls have somewhat higher insulating

value than solid masonry walls because of the

air space between the backing and the facing.

This space also provides a barrier against

moisture penetration when the wall is properly

flashed. Paint or plaster may be applied directly to the inside face, or the wall may be used without

any finish. If greater thermal insulation is desired, for example in northern latitudes, the

inside face may be furred and plastered.

2. Compressive Load

The results for wall specimens AU-Cl, C2,

and C3 are shown in table 10 and in figures 12 and 13. The compressive loads were applied to both

the facing and the backing, 3.25 in. from the

inside face. The shortenings and sets shown in figure 11 for a height of 8 ft were computed

from the values obtained from the compressometer readings. The gage length of the compressometers was 7 ft 4 in. Each of the specimens failed by breaking of

the tile in the upper two or three courses. No

failure of the brick facing was observed.

3. Transverse Load

Wall specimen AU-T3 under transverse load

is shown in figure 14. Tlie results are shown in table 10 and in figure 15 for wall specimens

AU-Tl, T2, and T3, loaded on the inside face,

[10]
and in figure 16 for wall specimens AU-T4, T5,

and T6, loaded on the outside face. Table 10.

Structural properties, wall AU

[Weight. fi2.3 lb/ft*]

Load

Do.

Average,

/Outside f 1 span, 7 ft

Average.

Do.

DoLoad applied

(Upper end, 3.26

I in. from the in-

( side face.

Average.

flnside face;

1 span, 7 ft 6 in.

face;

6 in.

Inside face_

Average

Outside faceAverage

Inside face;

span, 7 ft 6 in.

AverageOutside face; span, 7 ft 6 in.

Average

Near upper endAverage

Speci' men

desig- nation

CIC3

TlT2

TSnT6T6

PIPB

PS

PiPSP6

Fail- ure of loaded

face, height

of drop

Fail- ure of opposite

face, height

of drop

3.0

3.5 3.5

3.3

2. 5 3.0

3.0

2.8

RlR2

RS

3.5 3.5 4.0

3.7

2.5

2.5

3.5

2.8

Maxi- mum

height

of drop

3.5

3.5 4.0

3.7

2.5

3.0

3.5

Maxi- mum

load

•Kips/ft

27.

2fi. 4 29.8

27.8

17.0 23.8

23.7

21.5

30.0

26. 2

31. 2

29. 1

lb

' 1, 000

> 1. 000

!• 1,000

' 1, 000

' 1.000

1, 000

» 1.000

'Kips/ft

5. 34

5. 11

5. 03

5. 16

" A kip is 1,000 lb.

' Specimen did not fail. Test discontinued. Each of the specimens Tl, T2, and T3 failed by rupture of the bond between the brick and

the mortar at a bed joint at midspan in the facing, and rupture of the bond between the tile and the mortar at one or two bed joints at or between the loading rollers in the backing. In each case the failures in the tile backing oc- curred at joints having ties. For specimens T4, T5, and T6 at loads of

27.5, 17.2, and 15 lb/ft^ respectively, the bond

between the tile and the mortar ruptured at a bed joint near midspan in the backing. At the

maximum load each of the specimens failed by

24

20

16

I 12

^ 8

I

0

u

• O

m O O

1

m Cj/( )

o/o

1p \ ?/ °

11

1 j

\l•go

AU

Figure 12.

0.02 OM 0.06

shorfenitK^ injdff

-Compressive load on wall AU.

Load-shortening (open circles) and load-set (solid circles) results for specimens AV-Cl, Ci, and CS. The load was applied 3.25 in. from

the inside face. The loads are in kips per foot of actual width of speci- men.

rupture of the bond between the brick and the

mortar at a bed joint between the loading roll- ers in the facing. For specimens TI^. and T5

the failure of the brick facing occurred at joints

having ties.

4. Concentrated Load

The results are shown in table 10 and in fig- ure 17 for wall specimens AU-Pl, P2, and PS,

loaded on the inside face, and in figure 18 for wall specimens AU-PIi., P5, and P6, loaded on

the outside face. The concentrated loads were applied to the

faces of the specunens at midwidth and midway between ties. The indentations after a load of 1,000 lb had been applied were 0.002,

0.018, 0.002, 0.001, 0.001, and 0.004 m. for

specimens PI, P2, PS, P4, P5, and P6, respectively, and no other effect was observed.

5. Impact Load

Wall specimen AU-I2 during the impact

test is shown in figure 19. The results are

[11]
[12]
I

K)

1 m

( o

O

T

(

(io

fl

(1

30

0.4

defiedion

0.6

in Figure 15.—Tranaverse load on ivall AU, load applied to inside face.

Load-deflection (open circles) and load-set (solid circles) results for speci- mens A U-Tl, T2, and T3 on the span 7 ft 6 in. The deflections and

sets are for a gage length of 7 ft 4 in., the gage length of the deflec- tometers. shown in table 10 and in figure 20 for wall

specimens AU~I1, 12, and IS, loaded on the in- side face, and in figure 21 for wall specimens

AU-I4, 15, and 16, loaded on the outside face. The impact loads were applied to the center

of the inside face of specimens II, 12, and 13,

the sandbag strilting the tile backing at midspan, one tile course below the nearest joint with

ties. For each of the specimens II, 12, and IS

at drops of 2, 2, and 3 ft, respectively, the bond

between the brick and the mortar in the facing

ruptured transversely (across the specimen) near midspan. For specimens II and IS the breaks

occurred at joints with ties. At drops of 2, 2.5,

and 3 ft for specimens II, 12, and IS, respectively, the bond between the tile and the mortar

in the backing ruptured transversely (across the

specimen) near midspan. The rupture in specimen II occurred at a joint with ties. At higher

drops both the backing and the facing failed by

opening of these cracks or by the formation of new cracks. In all cases the tile backing failed

first, followed by the failure of the brick facing

at the next drop.

^1 25

^ 20

15*

10^

0<

Dm,

Tl

w

f

•• r

D 0

0 0.2 0.4 0.6

def/ec Hon in.

Figure 16.—Transverse load on wall AU, load applied to outside face.

Load-deflection (open circles) and load-set (solid circles) results for speci- mens A U-T4, TB, and T6 on the span 7 ft 6 in. The deflections and

sets are for a gage length of 7 ft 4 in., the gage length of the deflec- tometers.

^1000

^800

^600

1400

^200

Oi

—

—•-•

•

V

/

1

1•

1•

1 •

/le/-/ 0 002 0.04 0.06

indenfahon in. Figure 17.

Concentrated load on wall AU, load applied

to inside face.

Load-indentation results for specimens A U-Pl, P2, and PS.

[13]

—•- o —•-^

/»— Q

W w

1

AMI— T

1

o

AU-I 0 OA 0.8 1.2

defiedion in

Figure 20.

Impact load on wall AU, load applied to inside face.

Height of drop-deflection (open circles) and height of drop-set (solid

circles) results for specimens A U-Il, 12, and IS on the span 7 ft 6 in.

2

1—

«

—

1 rO—

1

T

/

—o- o

/

/U

S_ - AU-4 0 0.2 0.4 0.6

deflecfion in

Figure 21.

Impact load on wall AU, load applied to outside face.

Height of drop-deflection (open circles) and height of drop-set (solid

circles) results for specimens 17-/^, IB, and 16 on the span 7 ft 6 in.

The impact loads were applied to the center

of the outside face of specimens 7^, I^, and 16,

the sandhag striking the brick facing at midspan, between joints with ties. For each of the

specimens 14, 15, and 16 at drops of 1 .5, 2, and

2 ft, respectively, the bond between tbe tii(^ and

the mortar in the backing ruptured transversely

(across the specimen) at or above midsj)aii. For

specimen 16 the break occurred at a joint with

ties. At drops of 2, 2, and 3 ft for specimens

14, 15, and 16, respectively, the bond between

the brick and the mortar in the facing ruptured

transversely (across the specimen) at or above

midspan. The breaks in specimens I4 and 15

occurred at joints with ties. At higher drops

both the backing and the facing failed by opening of these cracks or by the formation of a new

crack in the tile backing. For specimens I4

and 16 both the backing and the facing failed at the same drop. For specimen 15 the tile backing failed first, followed by failure of the brick

facing at the next drop.

6. Racking Load

Wall specimen AU-Rl under racking load is shown in figure 22. The results for wall speci- mens AU-Rl, B,2, and R3 are shown in table

10 and in figure 23. The racking loads were applied near the upper end of each specimen to a bearing plate

covering both the facing and the backing, and

the stop was also in contact with both. The

deformations and sets shown in figure 23 for a height of 8 ft were computed from the values

obtained by the measuring-device readings.

The gage length of the vertical measuring device was 6 ft 5 in. for specimen Rl and 6 ft 0 in. for specimen R3. The gage length of the

horizontal measuring device was 5 ft 0 in. for both specimens. The deformations and sets for specimen R2 are not given in figure 23 because

there was relative motion between the facing

and backing which caused errors in the readings.

At loads of 2.92, 4.75, and 3.75 kips/ft for specimens Rl, R2, and R3, respectively, the

tile backing of each specimen cracked in the

bed and head joints, along the diagonal from

the load to the stop. In addition a few tile were broken. At the maximum load the facing

and the backing of specimen Rl and the backing of specimens R2 and RS failed by rupture of

[15]
[16]
the bond between the masonry units and the

mortar in the bed and head joints, along the

diagonal from the load to the stop. The fac- ings of specimens R2 and US did not fail.

The drawings of the specimens were pre- pared by E. J. Schell, G. W. Shaw, and T. J. Hanley of the Bureau's Building Practice and

Specifications Section, under the supervision of V. B. Phelan.

The structural properties were determined

by the Engineering Mechanics Section, under

the supervision of H. L. Whittemore and A. H.

Stang, and the Masonry Construction Section,

under the supervision of D. E. Parsons, with

the assistance of the following members of the

professional staflt": C. C. Fishburn, F. Cardile, R. C. Carter, H. Dollar, M. Dubin, A. H.

Easton, A. S. Endler, C. D. Johnson, P. H.

Petersen, A. J. Sussman, and L. R. Sweetman.

VI. SELECTED REFERENCES

1. Reinforced Brick Masonry

M. Vaugh, Reinforced brickwork, Bui. Univ. Missouri Eng. Exp. Sta. Series 28, 29, No. 37 (1928).

L. B. Lent, Possibilities for reinforced brickvwrk, Eng.

News-Record 102, 304-6 (1929). Reinforced brickwork used in much Japanese construction,

Eng. News-Record 105, 142-3 (1930).

S. Kanamori, Reinforced brickwork opens greater possibilities. Brick and Clay Record 77, 96-100 (1930). A practical test for reinforced brickwork. Brick and Clay

Record 78, 532-4 (1931).

Results of tests on ten demonstration structures with sum- mary covering tests on thirteen structures, Nat. Brick

Mfrs. Research Foundation, Bui. No. 4 (1932).

J. R. Shank, Reinforced unit masonry, Ohio State Univ.

Eng. Exp. Sta. News 4, No. 2, 3 (1932).

J. W. Whittemore and P. S. Dear, An investigation of

the performance characteristics of reinforced brick masonry slabs, Virginia Polytech. Inst., Bui. No. 9

(1932). Wall of reinforced brickwork incloses steel water tank, Eng. News-Record 108, 892-3 (1932). Reinforced brickwork: A new construction material,

Eng. News-Record 109, 71-4 (1932). D. E . Parsons, A. H. Stang, and J. W. McBurney,

Shear tests of reinforced, brick masonry beams, BS J. Research 9, 749 (1932) RP504.

H. S. Haworth, Reinforced brick masonry for industrial

use, Civil Eng. 3, 204-6 (1933). M. O. Withey, Tests on brick masonry beams, Proc. Am.

Soc. Testing Materials 33, pt 2, 651 (1933).

J. H. Hansen, Developments in reinforced brick masonry,

Proc. Am. Soc. Civil Eng. 59, 407-27 (1933). A. L. Harris, A. H. Stang, and J. W. McBurney, Compressive strength of steel columns incased in, brick walls, BS J. Research 10, 123 (1933) RP520.

H. Filippi, Reinforced brick masonry—principles of de- sign and construction, Common Brick Eng., Brick

Mfrs. Assn. of Am. 3 (1933).

J. W. Whittemore and P. S. Dear, A comparison of the performance characteristics of reinforced brick masonry

slabs and reinforced concrete slabs, Virginia Polytech.

Inst., Bui. No. 15, 27, No. 1 (1933).

J. Vogdes, A unique reinforced brick masonry fence. The

Clay Worker, 100, 154-5 (1933). Inge Lyse, Tests of reinforced brick columns, .1. Am.

Ceram. Soc. 16, 584 (1933). M. O. Withey, Tests of reinforced brick masonry columns,

Proc. Am. Soc. Testing Materials 34, pt. 2, 387

(1934). H. D. Williamson, Reinforced brickwork, Rensselaer

Polytech. Inst. Bui., Eng. and Sci. Series No. 46

(1934). Reinforced brick masonry slab tests. Construction

(Canada) p. 139-41 (Oct.-Nov. 1934). Load tests on structures of reinforced brick masonry. The

Canadian Eng. 67, No. 26, 3-6 (1934). C. H. Fork, Proving reinforced brick masonry as a

structural material. Brick and Clay Record 90, 323-8 (1937). C. H. Fork, Brick school built earthquake resistant, Eng.

News-Record, 119, 227-9 (1937).

2. Cavity (Hollow) Walls

Hollow walls of brick and how to build them. Common

Brick Mfrs. Assn. of Am., Pub. No. 11 (1925, Revised

1930). A. H. Stang, D. E. Parsons, and J. W. McBurney, Compressive strength of clay-brick walls, BS J. Research 3, 507 (1929) RP108.

Cavity wall construction. Pamphlet issued by the Clay

Products Technical Bureau of Great Britain.

J. H. Hansen, Low cost walls can be designed with clay

brick. Brick and Clay Record 88, No. 5 (1936). The barrier wall, Eng. Notes on Brick Masonry, The

Brick Mfrs. Assn. of Am. Bui. No. 2 (1936).

J. H. Hansen, Cavity walls. Brick Mfrs. Assn. of N. Y. Tech. Bui. No. 10 (1938). Washington, March 21, 1939.

[17]

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