National Bureau of Standards

JUL 2 2 1943
BUILDING MATERIALS AND STRUCTURES REPORTS

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BMSl Research on Building Materials and Structures for Use in Low-Cost Housing 10^

BMS2 Methods of Determining the Structural Properties of Low-Cost House Constructions 10^

BMS3 SuitabiUty 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 PermeabiUty 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 10^ BMS12 Structural Properties of "Steelox" Constructions for Walls, Partitions, Floors, and Roofs

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

the Wheeling Corrugating Co 10^ BMS16 Structural Properties of a "Tilecrete" Floor Construction Sponsored by Tilecrete Floors, Inc m

BMSl7 Sound Insulation of Wall and Floor Constructions 10 Supplement to BMS 17, Sound Insulation of Wall and Floor Constructions „_ 5(i BMS18 Structural Properties of "Pre-fab" Constructions for Walla, Partitions, and Floors Sponsored by the Hamischfeger Corporation 10^ BMS19 Preparation and Revision of Building Codes 16)5 BMS20 Structural Properties of "Twachtman" Constructions for Walls and Floors Sponsored

by Connecticut Pre-Cast Buildings Corooration 10^ BMS21 Structural Properties of a Concrete-Block Cavity-Wall Construction Sponsored by the National Concrete Masonry Association 10^ BMS22 Structural Properties of "Dun-Ti-Stone" Wall Construction Sponsored by the W. E. Dunn Manufacturing Co 10f5 BMS23 Structural Properties of a Brick Cavity-Wall Construction Sponsored by the Brick

Manufacturers Association of New York, Inc 10^ BMS24 Structural Properties of a Reinforced-Brick Wall Construction and a Brick-Tile CavityWall Construction Sponsored by the Structural Clay Products Institute 10^ BMS25 Structural Properties of Conventional Wood-Frame Constructions for Walls, Partitions,

Floors, and Roofs 16^ BMS26 Structural Properties of "Nelson Pre-Cast Concrete Foundation" Wall Construction

Sponsored by the Nelson Cement Stone Co., Inc lOi

BMS27 Structural Properties of "Bender Steel Home" Wall Construction Sponsored by the Bender Body Co 10^ BMS28 Backflow Prevention in Over-Rim Water Supplies 10^ BMS29 Survey of Roofing Materials in the Northeastern States lOjS BMS30 Structural Properties of a Wood-Frame Wall Construction Sponsored by the Douglas

Fir Plywood Association 10^ BMS31 Structural Properties of "Insulite" Wall and "Insulite" Partition Constructions Sponsored by The Insulite Co , . — 15^

[List continued on cover page m]
UNITED STATES DEPARTMENT OF COMMERCE • Jesse H. Jones, Secretary

NATIONAL BUREAU OF STANDARDS • Lyman J. Briggs, Director

BUILDING MATERIALS

and STRUCTURES

REPORT BMSlOl

Strength and Resistance to Corrosion of

Ties for Cavity Walls

by

CYRUS C. FISHBURN

ISSUED JULY 1, 1943

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 ot reports are to be construed accordmgly

UNITED STATES GOVERNMENT PRINTING OFFICE • WASHINGTON • 1943

FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, U. S. GOVERNMENT PRINTING OFFICE

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Foreword

Ties for cavity-wall construction are usually specified in accord- ance with empirical rules for a minimum thickness and a minimum

spacing. This report presents data on the resistance to axial loads

of wall ties and the corrosion resistance of some steel ties exposed to weathering, either when unprotected or when coated with corrosiveresistant metals, portland cement, or a bituminous paint.

Lyman J. Briggs, Director.

[II]
Strength and Resistance to Corrosion of Ties for Cavity Walls

by CYRUS C. FISHBURN

CONT

Page

Foreword ii

I. iBtroduction 1 II. Specimens 2

1. Materials 2

(a) Ties 2

(b) Brick 3

(c) Mortars 3

(d) Cementitious and coal-tar- paint coatings 3

2. Construction of specimens 4

(a) Compressive-strength speci- mens 4

(b) Tensile-strength specimens 5

(c) Indoor-weathering specimens. _ 5

(d) Outdoor-weathering specimens^ 5

III. Method of testing 5

1. Tests for structural strength 5

(a) Compressive-strength test 5

(b) Tensile-strength test 5

ABSTRACT

The resistance to axial loads of ties for cavity walls was determined by testing steel and cement-asbestos

ties when they were embedded at the ends in brick masonry. Fourteen different ties and three mortars were represented in a group of about 110 specimens.

The ties, with one exception, when spaced one to every

3 ft 2 of wall area, provided connections of ample

strength to resist the usual lateral forces to which

cavity walls are subjected.

The corrosion resistance of some of the steel ties was

measured by exposing them when unprotected and when

coated to accelerated and to outdoor weathering.

I. INTRODUCTION

The cavity wall, a form of hollow masonrywall construction widely nsed in Great Britain,

and to some extent elsewhere, consists of two

parallel tiers of unit masonry separated by a continuous cavity about 2 in. wide. The tiers are joined by ties, usually consisting of bent steel rods or wires spaced one for each 2 or 3 ft ^ of wall area. According to Fitzmaurice,^ properly

1 Principles of Modern Building, vol. 1, Walls, Partitions and Chimneys, London (1939), p. 159.

E NTS

Page

III. Method of testing—Continued

2. Weathering tests 5

(a) Indoor-weathering exposure 5

(b) Outdoor-weathering exposure. 5 IV. Results of the strength tests 5

1. Compressive strength 5

(a) Effect of shape and diameter of

steel ties 6

(b) Strength of specimens containing Copperweld, corrugated

galvanized steel, and cementasbestos ties 6

2. Tensile strength 6

3. Discussion of strength data 7

V. Results of weathering tests 7

1. Indoor exposure 7

2. Outdoor exposure 8

VI. Summary and conclusions 8

1. Compressive strength 8

2. Tensile strength 8

3. Corrosion of the ties 9

built cavity construction has two desirable

features, namely, a high resistance to rain

penetration and a greater heat insulation than

solid walls of the same materials and thickness.

Available evidence,^ based largely on experience, indicated that steel ties equivalent in

strength to }^-in. steel bars have adequate

strength when well anchored in strong mortar.

Also that galvanized iron or steel ties are likely

to have a satisfactory durability for use in ordinary buildings under conditions of normal

exposure. For monumental structures or for unusually corrosive conditions more resistive

materials would be preferable.

The tests described in this report were made

to determine : (a) the strength of ties under axial

tensile and compressive loads and .(b) the cor- rosion resistance of steel ties coated with vari- ous materials. Fourteen different types of ties and three moi'tars were represented in the

specimens subjected to strength tests. The

ties exposed to accelerated or outdoor weathering were either unprotected or coated with

' Footnote 1, p. 164 to 166.

[1]
copper, zinc, portland-cement mortar, or coal- tar paint.

II. SPECIMENS

1. Materials

(a) Ties

The ties used in the compressive-strength

specimens are illustrated and described in figure 1 and table 1, respectively. Ties 1 and 2

(fig. 1), made of copper-coated steel, are known

as Copperweld nonrusting cavity-wall ties, and

were donated by the Copperweld Steel Co.,

Glassport, Pa. Tie 1 was No. 182-30 type

Z-6300. Tie 2 was No. 204-30.

Ties 3 to 8, inclusive, were made of concretereinforcing steel wire donated by the Pittsburgh

Steel Co., Pittsburgh, Pa. They differed in

thickness (No. 6, 8, or 10 gage) and in shape

(table 1). Tie 8, of rectangular shape, was made of the 8-gage wire, and had the ends of

the whe butted at the center of one end of the

tie. The square ties 9, 10, and 11 were cut from welded wire fabric, donated by the PittsTable 1.

Wall ties

Tie

number Kind of material

w

Over-all dimensions

J. y yKi

Length |

Width

Thickness.

In. 7?!. In.

1 Copperweld ^ 6 6 0. 183

2 do 6 6 .207 Do.

3 Steel ^ Q 6 G . 188 Do

4 do 8 6 4 .158 Do!

5 do 8 6 6 .158 Do.

6 do 8 6 8 .158 Do.

7 do 10 6 6 .131 Do.

8 Steel b 8 6 4 .158 Rectangular, ends butted on 4 in. side.

0 do b 6 7 7 .192 Welded wire fabric, 6- by 6-in. mesh.

10 do 8 7 7 .161 Do.

11 do 10 7 7 .135 Do.

12 Steel, galvanized"- 24 6.8 0.94 .06 Corrugated, 5^-in. pitch.

13 Cement - asbestos 7 4.5 .275 1 -shape, perforated at board. ends.

14 do 7 4.5 .134 Do.

a Furnished by the Copperweld Steel Co., Glassport, Pa. Tie 1 was

No. 182-30, type Z-6300; tie 2 was No. 204-30.

b Brisfht basic wire made by the Monessen, Pa. plant of the Pittsburgh

Steel Co.

" Purchased from Fries, Beall & Sharp Co., Washington, D. C.

Figure 1.

Ties for compressive-strength specimens.

[2]
burgh Steel Co., and made at the same plant

of a similar steel as that used in ties 3 to 7. The strengths of the wire in the welded fabric

and of those used in ties 3 to 8 were approximately equal. The average yield strength (off- set=0.2 percent) and the average tensile strength of the wires ^ were, respectively,

86,000 and 90,000 lb/in.'

Tie 12 was a corrugated galvanized sheet

strip of the type often used in brick veneer on wood-frame construction.

The cement-asbestos ties 13 and 14 contained

six J^riii. -diameter holes, were of like shape, and

were % and }i in. thick, respectively. The ties were cut from sheets of cement-asbestos fiber

board weighing about 120 Ib/ft^. The moduli

of rupture, when diy and when wet, of strips

cut from the %-in. -thick board were, respectively, 6,850 and 3,400 Ib/in.^ Deflection measurements made on strips 4 in. wide loaded at the center of an 8-in. span indicated that the

moduli of elasticity of the strips, when dry and

when wet, at loads of 0.6 the vdtimate were,

respectively, 2,700,000 and 1,800,000 Ib/in.^

The tensile strength, when dry, of the M-in. board was 3,240 Ib/in.^ The tensile strengths

of the )8-in. board, when dry and when wet, were, respectivelj^, 2,690 and 1,340 Ib/in.^

(b) Brick

The brick * used in the specimens were sidecut shale units made in Alartinsburg, W. Va.

They had an absorption of 3.1 percent during

24-hr. cold immersion. The compressive strength

and the modulus of rupture of the brick were,

respectively, 15,700 and 2,030 Ib/in.^

(c) Mortars

The proportions and physical properties of

the three mortars, designated as mortars H, AI,

and L, are given in table 2. They differed in strength and in the relative proportions of portland cement and hydra ted lime. The cementing materials were Medusa brand portland

cement, which met the physical requirements

of Federal Specification SS-C-191a, and Miracle

' Tested in accordance with the Standard Methods of Tension Testing

of Metallic Materials (E8-36) A. S. T. M. Standards, 1939.

* The briclc were similar to brick A, described in Building Materials and Structures Report BMS82.

hydrated lime manufactured by the G. & W. H.

Corson Co., Plymouth Meeting, Pa. A sieve

analysis of the Potomac River building sand

used in the mortai-s is given in table 3. The mortars were proportioned by weight,

and mixed in a batch mixer having a capacity of

0.6 ft.^ The water used for tempering was

adjusted in amount to give an initial flow ^ of

110 to 115 percent. Since the Miracle brand

hydrated lime was higlily plastic, the water

retentivity of the mortars was much greater

than that usually obtained with mortars containing dry lime hydrates (table 5, BMS82).

Six 2-in. cubes made from each batch of mortar

were cured as indicated (table 2) and tested in compression when 28 days old.

Table 2.

Proportions and physical properties of mortars

Properties of mortars

Mortars H M L

Proportions!

of cement, Iby volume .

.

1:0. 25:3. 0.._. 1:1:6.0 1:3:12.0. limp, and (by weight 1:0.11:2.6 1:0.42:5.1 1:1.28:10.2. sand. » J Average water content, percentage by weight of

17.7 20.4 22.5. dry materials.

2,450 800..-- - 230. 4,450 1,330 270.

• Proportioning was by weight, assuming that portland cement weighed

94 lb/ft 3, Miracle brand hydrated lime 40 lb/ft 3, and that 1 ft 3 of loose, damp sand contained 80 lb. of dry sand.

•> The initial flow of the mortars, determined according to Federal

Specification SS-C-181b, was about 110 percent.

° Strength at age of 28 days of 2-in. cubes molded in accordance with

paragraph F-4m of Federal Specification SS-C-158. Dry-cured cubes were removed from the molds when 2 days old and stored in air at 70°F

until tested. Wet-cured cubes were removed from the molds when

2 days old, stored in air at 70°F in the damp closet for 5 days, and then immersed in water at 70°F until tested.

Table 3.

Sieve analyses of sand

U.S. standard Sieve , A— U. S. Standard Sieve Amount

passing

4 -. Percent100.

0

99.8 97.0

30 Percent

79.0

27.5 4.6

8 50

16 100

(d) Cementitious and coal-tar-paint coatings

The protective coatings applied to ties 3, 4, and 7 embedded in the weathering specimens were mortar M, a coal-tar paint, and a neat

portland-cement paste containing 40 percent

by weight of water. The paint was Eternium

' Measured in accordance with Federal Specification SS-C-l81b.

[3]
brand made and donated by the Barrett

Division of the Allied Chemical & Dye Corporation, New York, N. Y. The ties treated

with neat cement and Eternium paint were

dipped in the coating material, and the coatings were hardened in air before the ties were placed

in the specimens. The ties dipped in mortar

M were immediately embedded in the

specimens.

P/as^er <?/ Par/s cap- 2

ik-.,= -6-

"""1

P/an V/eiv

-ffas/er ofPans c-cp

P/an y/eiv

End V/'eiy

Compress/i^e 3freng/ft Specimen

€nd y/etv

Tensi/e Sfreng/h Spec/'meo

Figure 2.

Drawing of compressive- and tensile-si rcngth

speci7nens, showing embedment of Z-shaped ties.

2. Construction of Specimens

(a) Compressive-strength specimens

A typical compressive-strength specimen is illustrated in figure 2. A T-shaped jig was used

to aline the brick in the first course of the speci- mens so that the distance between the brick was

2 in. The ties were alined by eye in the mortar

bed, and they were covered with mortar before

the upper bricks were laid. It required about

35 min. to make 30 specimens, and the mortars H and M were retempered once dm*ing

this interval, if and when the mortar has stif- fened to a flow of 100 percent or less. The edges

of the joints were cut flush with the surfaces of

the brick. The average joint thiclmess in

specimens containing metal ties was %6 in., that in specimens containing cement-asbestos

ties (tie 13) was % in. Joints containing mortar

L averaged nearly in. less in thickness than

did the joints containing the other mortars.

At least five like specimens of each kind of tie and mortar were made and tested after curing

in air at 71°F for 28 days.

Figure 3.

Outdoor-weathering specimens. The small (indoor) •sM.'athermg specimens were placed above the w allettes after the indoor tests were completed.

[4]
(b) Tensile-Strength Specimens

The ties in the tensile-strength specimens were embedded at one end only (fig. 2). Five like specimens were made of each kind of mortar

for ties 3 to 7, inclusive. They were stored in

air at about 71° F for 28 days before they were

tested.

(c) Indoor-Weathering Specimens

The indoor-weathering specimens were similar to the compressive-strength specimens,

except that each contained two like ties. The ties used were Nos. 2, 3, 4, 7, and 12, of which the steel ties 3, 4, and 7 were either

uncoated or protected by coatings of Eternium,

neat cement, or mortar M.

(d) Outdoor-Weathering Specimens

The outdoor-weathering specimens, figure 3, were cavity-type wallettes. These specimens were three stretcher brick in length, five stretcher courses high, and were topped with a

covering course of header brick. The cavity was 2 in. wide. Mortar H was used in all but

the covering courses, which contained mortar i.

Two ties were placed near the ends of the

specimens in the bed joint between the first and second courses, and one tie was placed at midlength of the wall between the fourth and

fifth courses. The joints were cut flush with

the surfaces of the brick. The ties were of the same kind and were given the same protective

coatings as those represented in the indoorweathering specimens.

III. METHOD OF TESTING

1. Tests for Structural Strength

(a) Compressive-Strength Test The ends of the compressive-strength speci- mens were capped with a thin coating of cal- cined gypsum (see fig. 2) about 2 days before

they were tested. Steel loading plates containing a )^-in-wide slot were placed over the

caps, and the slots in the plates were alined

with the mortar joints so that no pressure was

exerted directly against the joint. The speci- mens were loaded to failure, and the type of

failure was observed. The rate of load application was about 400 Ib/min.

(b) Tensile-Strength Test The specimens were capped with gypsum and

supported on a slotted steel plate with the end

of the tie projecting through a hole at the center

of the slot. A pull was exerted on the end of

the tie until failure occiuxed, and the type of

failure was obsei'ved.

2. Weathering Tests

(a) Indoor-Weathering Exposure

Each specimen was covered with a strip of

damp burlap and was supported above heated

water in a metal pan. The ends of the burlap

drapings hung in the water, and the pan was

fitted with a cover so that the burlap over the

specimens remained moist. The temperatiu-e

of the humid air adjacent to the specimens

ranged between 95° and 100° F. The speci- mens were exposed for 180 days, and the extent

of the corrosion of steel in the ties was observed.

(6) Outdoor-weather exposure

The specimens (fig. 3) were built outdoors at Washington, D. C, in June 1942 and exposed

to the weather.

IV. RESULTS OF THE STRENGTH TESTS

1. Compressive Strength

The type of failure, the average tie stress, and the compressive strength of the specimens

are listed in table 4. The specuneiis failed

either by budding of the ties or by crushing of

the mortar against the ends of the ties. The

strength of those that failed in budding was

affected by irregularities of alinement of the

ties in the specimens, but it is probable that the

accuracy of tie alinement was equal or better

than that usually found in cavity-wall construction.

[S]
Table 4.

Compressive strength of wall tie specimens

'

Tie number

11, 12

13.

14.

Area

of cross

sec- tion

in.'

0. 0263

.0336

.0278

.0196 .0196

.0196

.0135 .0392

.0579 .040

.0286

.019

.412

.201

Kind of failure >> and kind of mortar M

BM

Bm

B

B

B

B

Bm

Mb

B

B

B

Mb

B

MM

MbM

MM

M

BM

Maximum load on specimens and kind of mortar H M

lb

2, 070

3,880

2, 025

1, 140

1, 060

1, 150 600

2, 310

3, 740 2,440

1. 730

70

4, 370

lb 1,900

2, 180

1, 810 990

1,115

1, 120 520

2. 060

3, 000

2, 345

1,600

60

3, 580

2,065

lb970

1,030 780

860

770 800

660

1.010

1,370

1.500 1,100

Maximum compressive stress in ties and kind of mortar H

Ibjin.i

78, 700 115,300

72,900

58, 100

54, 100 58,600

44, ,500 58, 900

64.600

59, 900

60, 400 3,700

10, 600

M

lb/in.' 72, 200

64,800

65, 200

50, 500

56. 900

57, 100

38, 600

52, 500

52, 800

57, 600

55, 900

3.200

8, 700

10,300

lb/in.'

36, 900

30, 600

28, 100

43, 900

39, 300

40, 800

49, 000

25, 800

23, 700

36, 800

38, 400 4,700

4, 500

» Average values obtained from tests on groups of 5 or more like specimens,

b Key:B =Buckling or crushing of the tie between supports. M =Crusliing of mortar over the tie. iJm=Predominant buckling failure with 2 or more mortar failures. A-/6=Predominant mortar crushing with 2 or more buckling fail- ures.

(a) Effect of shape and diameter of steel ties

Over 90 percent of the specimens containing

ties 3 to 11, inclusive, embedded in mortars H

and M failed in bnckling of the tie. Specimens

containing mortar H were nearly 10 percent

stronger than those built of mortar M. As

would be expected, the ultimate stress developed in the ties was least for the single-stem

ties of the smallest diameter (10 gage). The

length of ear in ties 4, 5, and 6 (2, 3, and 4 in., respectively) had a slight but significant effect on the strength of specimens built of mortars

H and M, but had no significant effect on the

strength of those specimens that failed by crushing of the mortar (table 4). The rectangular,

double-stemmed ties, sustained approximately

twice the ultimate loads, as did the single-stem

Z-shaped ties. Specimens containing the square

tie 10, cut from welded fabric, were stronger

than those containing the narrower rectangular

tie 8.

(b) Strength of specimens contain ing Copperweld,

corrugated galvanized-steel, and cement-asbestos

ties The ultimate stresses developed in the Copperweld ties (tie 2) embedded in mortar Hwere

exceptionally high. Specimens containing these

ties embedded in mortar M failed by crushing

of the mortar, the average maximum bearing

stress over the 3-in. lear length was 3,500 b/in.l

The corrugated galvanixed-steel strips (tie 12) were extremely weak in compression, and care had to be taken in handling the specimens to prevent budding of the ties before they were

tested. Specimens containing tie 13, cut from portland-cement and asbestos fiber board, sustained

the greatest compressive loads of any of those

listed in table 4. The mortar M in some speci- mens containing these ties was crushed against

the ends of the ties, and the average maximum

bearing stress of this mortar on the ties was

about 2,900 lb/in. ^ Tie 14 approximately onehalf the thickness of tie 13 buckled at the same

stress when embedded in mortar M as did tie 13 embedded in mortar H.

The possibility of failure in )'4-in. -thick ties similar to tie 13, produced by a differential

vertical movement between the two faces of a cavity wall, was investigated. Assuming the

tie to be fixed at the inner faces of a 2-in. cavity, a modulus of rupture of 6,850 lb/in. ^ and a value

of E of 2,720,000 Ib/in.^ (calculated from observed beam deflections at 0.6 maximum load),

it was estimated that the tie may break if one

support was moved vertically 0.01 in. relative

to the other. The estimated vertical movement

required to break a tie Yg. in. thick was similarly

estimated to be 0.02 in.

2. Tensile Strength

The tensile-strength specimens, listed in table 5, failed by crushing of the mortar under

the tie, with subsequent splitting of the brickmortar assembly, by pulling out of the tie or by tension in the tie. Many of the ties in specimens that failed by pull-out or by mortar

crushing were necked, the reduction in area

usually occurring at or immediately below the

ear in the ties. Likewise, a partial bond failure

of the tie occurred in many specimens that

failed in tension of the tie or by crushing of the

mortar, and the ends of the ties often slipped

in the bed as much as }i in. Ties of 6- and 10-gage wire (ties 3 and 7)

embedded in mortar H faUed by pull-out; the

ties of 8-gage wire, similarly bedded, failed in tension (with two exceptions) , and the variation

in the length of ear had but a slight effect on

strength. An increase in the ear length of 8-

[6]
gage ties bedded in mortar M (ties 4, 5, and 6), however, did increase the strength of the speci- mens. All the 10-gage-wire ties (tie 7) bedded

in mortar L pulled out of the specimen, whereas

most of the specimens containing 6- and 8-gagewire ties, bedded in this mortar, failed by crushing of the mortar.

Table 5. —Tensile strength of ivall He specimens^

Tie number

Area

of cross

sec- tion

Kind of failure i> and kind of mortar

Maximum load and Ifind of mortarMaximum tensile

stress in ties and

Icind of mortar H M L H M L H M L

lb lb lb lb/in.'' Ib/inJ Ib/in.i 3 0. 0278 P Pm M 1,540 1, 570 1, 210 55, 500 56, 600 43, 600

4 .0196 T P M 1,470 1, 220 840 75, 000 62, 200 42, 800

5 . 0190 T" Tp Mp dl, 580 1,320 800 •180, 600 67, 300 40. 800

6 .0190 r« Tp Up dl, 550 1, 420 900 <i79, 000 72, 400 45, 900

7 .0135 p P P 890 870 540 65, 100 63, 700 39, 500

a Average values obtained from tests on groups of 5 like specimens

unless otherwise noted.

i> Key:A/= Crushing of mortar under tie followed by splitting of specimen. P=Pull-out of tie. T= Tensile failure of tie. Afp=Predominant crushing of mortar, with pull-out failure of 2 specimens. Pra= Predominant pull-out failure with motrar failure on 2 specimens. Tp=Predominant tensile failure with pull-out failure for 2 specimens.

" Four specimens failed in tension, 1 by pull-out of the tie. ^ Average of 4 specimens that failed in tension.

3. Discussion of Strength Data

Ties in cavity walls are intended to connect

the two tiers and to serve as struts or tension

members between them. Wall ties of the usual

type do not have sufficient flexural rigidity to transmit shear across the cavity. Consequently, when one tier is subjected to a vertical load,

only a small part of the load is transmitted to the other, and the two tiers do not exert common

action under such loading.

Z-shaped ties of X-in. round steel bars, similar except for diameter to tie 3, were used in cavity-wall specimens subjected to impact and

transverse loads ; ^ ties of Yu-in. wire, similar ex- cept for diameter to tie 8, were in other cavity

walls similarly tested.'' Weakness of the indi-

« Building Materials and Structures Reports BMS23, Structural Properties of a Briclc Cavity-Wall Construction Sponsored by the Briclf Manufacturers Association of New York, Inc., and BMS24, Structural Properties of a Reinforced Brick Wall Construction and a Brick-Tile Cavity- Wall Construction Sponsored by the Structural Clay Products Institute.

' Building Materials and Structures Report BMS21, Structural Properties of a Concrete-Block Cavity-Wall Construction Sponsored by the National Concrete Masonry Association.

vidual ties did not contribute to the failure of the walls. The strength of tie needed to assure that they

would not deform excessively under lateral loading before the failure of a wall will depend

upon such factors as the thickness of the tiers,

the properties of the masomy materials, and the

workmanship. Excepting tie 12, and assuming

a tie spacing of one to each 3 ft ^ of wall area, the data in table 4 indicate that any combination of the ties and mortars included in the

tests would provide connections of ample

strength to resist the lateral forces such as wind loads to which cavity walls are usually

subjected.

V. RESULTS OF WEATHERING TESTS

1. Indoor Exposure

The effects of the indoor-weathering exposure on the rusting of the ties are listed in table 6. The uncoated steel ties and those coated with

neat cement or mortar were lightly rusted in 10

days or less, and most of them were severely

rusted in 30 days. The cementitious coatings,

especially those of the mortar M, did not retard

rust formation, and even appeared to have had

an accelerating effect on rusting. Coatings of Eternium coal-tar paint afforded some protection, but within 120 days the ties were severely

rusted over portions adjacent to the inside faces

of the brick. It is possible that the coatings at these points were nicked with the trowel when

the mortar protruding from the joints was cut away.

The copper coatings on the Copperweld ties

(tie 2) were darkened by the exposure, but no

evidence of rusting of the steel beneath the

copper was noted. One cut edge of one galvanized tie (tie 12) showed two very small and

barely perceptible rusted spots after 180 days

of exposure. A white discoloration was noted on the underside of these ties after 65 days of exposure.

The specimens were handled frequently during the exposure period, and it is possible that

the high temperatures during weathering and

the flexure of the ties during handling produced some damage to the coatings of Eternium paint

and to those of cementitious materials.

[7]
Table 6.

Results of weathering ex-posure tests of coated and uncoated steel wall ties

Tie number Kind of tie

2..

3..

4..

7.. 3-

4_.

7..

3-.

3-.

4-

7-12

Copperweld

Steel wire__. DoDo

Steel wire.. Do.

Do_ DoDo.

Kind of coating

Do

Do

Corrugated

steel.

Copper _. No coating do

do Portland ce- ment.

do

do Mortar M Eternium coal- tar paint. do

do

Galvanized

Indoor-weathering time re- quired for de- velopment of rust as indi- cated by degree of rusting •>

Dayn Days Days

Outdoor-weathering time re- quired for de- velopment of rust as indi- cated by " de- gree of rusting i>

Days Days Days

25

20

30

(')

(«)35

35

(')

(') (')

a Dashes indicate no failure was noted during an exposure period of 6 months.

b Liijht rusting was the first visible rusting, Moderate rusting was the formation of alight crust or caking of rust. No visible enlargement of tie diameter; and, severe rusting was a thick encrustation of rusl, irregular in

color with a noticeable enlargement of tie diameter, and accompanied by

pitting of the ties.

o Not noted.

<> A white discoloration, probably of metallic salts was noted on the underside of the ties at 60 days. There was no rusting noted at 120 days. At ISO days, 2 very small rust spots were noted at 1 cut edge of 1 tie.

» No severe rusting noted at 70 days. At 180 days, severe rusting and

cracking of the cement was noted. / Moderate to severe rusting, principally at the ends of the ties, was

noted at 180 days.

2. Outdoor Exposure

As can be noted (table 6) the uncoated steel

tics corroded in less time when exposed to the

outdoor than to indoor weathering. The ce- mentitious coatings seemed to offer better protection to the ties when exposed outdoors than

to those weathered indoors, but it is possible

that rust on the ties in the outdoor-weathering

specimens did not become noticeable until the

corrosion of the steel had. cracked the coatings.

Ties coated with Eternium paint were moderately to severely rusted at points adjacent to the inner faces of the brick, after 180 days of exposure.

There was no rusting of steel in the ties coated with copper or zmc (ties 2 and 12,

respectively).

VI. SUMMARY AND CONCLUSIONS

Ties for cavity-wall construction were tested

in tension and compression when embedded at the ends in brick-mortar assemblies spaced to

give a 2-in. cavity. Most of the ties were made of 6-, 8-, or 10-gage concrete-reinforcing

steel wire, cut either from welded fabric or from

coiled lengths. Other ties that were tested were Copperweld copper-coated Z-shaped steel ties, corrugated and galvanized steel strips, and

I -shaped ties cut from sheets of cement-asbestos

board. Tkree kinds of mortar were used, designated as H, M, and L, and mixed in the

respective volume proportions of 1 : 0.25 : 3, 1:1:6,

and 1:3:12.

Some of the ties coated with neat cement,

mortar M, Eternium brand coal-tar paint, copper, or zinc, were exposed outdoors and others

to artificial indoor weathering.

The following pertains to the structural

strength of the specimens and to the corrosive

effects on the plain and coated steel ties produced by exposure indoors to warm humid air and to outdoor weathering.

1. Compressive Strength

(a) Brick-mortar assemblies containing ties of 6-, 8-, and 10-gage steel wire embedded in mortars H and Mfailed by buckUng of the ties

;

when the ties were embedded in mortar L the

specimens failed by crushing of the mortar

against the ends of the ties. (b) Specimens built with mortar H that

failed by buckling of the ties were nearly 10

percent stronger than similar specimens built

with mortar M.

(c) Increase in the length of ear on Z-shaped

ties, from 2 in. to 3 or 4 in., resulted in a slight

but consistent increase in the strength of the

specimens.

(d) Specimens containing a square tie cut from welded wire fabric of 6-in. mesh were

stronger than those containing a rectangular

tie 4 in. wide (of the same kind and diameter of

steel wire) bent from one piece with butted, not

welded, ends.

(e) I-shaped cement-asbestos ties with stems

IK by }^ in. in cross section were stronger than

two-stem ties of No. 6 gage welded steel- wire

fabric, 6-in. mesh.

2. Tensile Strength

(a) Z-shaped ties of 6- and 10-gage steel wire

embedded in mortar H pulled out of the mortar

beds; ties of 8-gage wke failed in tension.

[8]
(b) Most of the Z-shaped ties of the 6-, 8-, and 10-gage steel wire, embedded in mortar AI,

pulled out of the mortar beds, some of the 8-gage

ties with ears 3 and 4 in. long failed in tension.

(c) Most of the specimens containing Z- shaped ties of 6- and 8-gage steel wire, embedded

in mortar L failed by crushing of the mortar,

with subsequent splitting of the brick-mortar

assembly; ties of 10-gage wiie pulled out of the

mortar beds.

3. Corrosion of the Ties

(a) Light rust was observed on plain, uncoated steel wire dm'ing the first week of ex- o

posure, and these ties were severely rusted in about 30 days.

(b) Coatings of neat portland cement and

mortar were ineffective and cracked away from

steel ties that had rusted.

(c) Coatings of Eternium coal-tar paint pre- vented the corrosion of steel ties except where

the coatings had been nicked with the mason's

trowel during construction of the specimens.

(d) Zinc and copper coatings were effective in

preventing the corrosion of steel ties.

Washington, February 12, 1943.

[9]

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(5 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. Dimn Manufacturing Co 10^ BMS39 Structural Properties of a Wall Construction of "Pfeifer Units" Sponsored by the Wisconsin Units Co 10^ BMS40 Structural Properties of a Wall Construction of "Knap Concrete Wall Units" Sponsored

by Knap America, Inc 10(5 BMS41 Effect of Heating and Cooling on the Permeability of Masonry Walls lOjS BMS42 Structural Properties of Wood-Frame WaU and Partition Constructions With "Celotex"

Insulating Boards Sponsored by The Celotex Corporation 15(5 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-Bilt" 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 10(5 BMS48 Structural Properties of "Precision-Built" Frame Wall and Partition Constructions

Sponsored by the Homasote Co 10(5 BMS49 Metallic Roofijig 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 Tile- crete Co 10^ BMS52 Effect 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 Effect of Soot on the Rating of an Oil-Fired Heating Boiler _ 10^ BMS55 Effects of Wetting and Drying on the Permeability of Masonry Walls 10^ BMS56 A Survey of Humidities in Residences 10^ BMS57 Roofing in the United States—Results of a Questionnaire i 10^ BMS58 Strength of Soft-Soldered Joints in Copper Tubing... 10^ BMS50 Properties of Adhesives for Floor Coverings 10(5 BMS60 Strength, Absorption, and Resistance to Laboratory Freezing and Thawing 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 Wsdls,

Partitions, Floors, and Roofs Sponsored by Herman A. Mugler 15(5 BMS68 Performance Test of 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(5 BMS73 Indentation Characteristics of Floor Coverings 10^ BMS74 Structural and Heat-Transfer Properties of "U. S. S. Panelbilt" Prefabricated Sheet-Steel Constructions for Walls, Partitions, and Roofs Sponsored by the Tennessee Coal,

Iron, and Railroad Co 15(5 BMS75 Survey of Roofing Materials in the North Central States 15(5 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(5 BMS79 Water-Distributing Systems for Buildings 15^ BMS80 Performance Tests of Floor Coverings for Use in Low-Cost Housing: Part 4 15(5 BMS81 Field Inspectors' Check List for Building Construction (cloth cover, 5 by 7^ inches) 20^

[List continued on cover page irj
BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page iii] BMS82 Water Permeability of Walls Built of Masonry Units 20^ BMS83 Strength of Sleeve Joints in Copper Tubing Made With Various Lead-Base Solders 10^ 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 15^ BMS90 Structural Properties of "PHC" Prefabricated Wood-Frame Constructions for Walls,

Floors, and Roofs Sponsored by the PHC Housing Corporation 15fi BMS91 A Glossary of Housing Terms 15^ BMS92 Fire-Resistance Classifications of Building Constructions 25^ 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" WaUs 10^ BMS95 Tests of Cement-Water Paints and Other Waterproofings for Unit-Masonry Walls 150 BMS96 Properties of a Porous Concrete of Cement and Uniform-Sized Gravel 100 BMS97 Experimental Dry-Wall Construction With Fiber Insulating Board 100 BMS98 Physical Properties of Terrazzo Aggregates 150 BMS99 Structural and Heat-Transfer Properties of "Multiple Box-Girder Plywood Panels"

for Walls, Floors, and Roofs . 150 BMSlOO Relative Slipperiness of Floor and Deck Surfaces , 100 BMSlOl Strength and Resistance to Corrosion of Ties for Cavity Walls 100