TECHNICAL IKFORvIAT ION ON BUILDING KA3ERIALS

TIEN - 56

FOR JSE IN THE DESIGN OF LON-COST HOUSING

* * * * *

TxI3 NATIONAL BUREAN OF STANDARDS

UNITED STATES DEPART],iENT OF CO.RERCE

Washington, d . g.

.. Deo enter 1 5_,_ JL9.3 7_

MASONRY WALL RESISTANCE TO RAIN PENETRATION

t-itn a view to obtaining data which may he found of value in re- ducing the water leakage in masonry walls, the National Bureau of

Standards has recently completed tests under the direction of D. E.

P-a sons, on 113 sample walls of different types of construction. The

investigation was planned to obtain information on the effect of the

a ol lowing factors on the permeability of masonry walls:

(a) Thickness, bonding of units, kind of brick of hollow unit,

kind of mortar and method of filling joints.

(b) wind pressure on walls.

(c) Re pointing ana waterproofing treatments.

tlie iT^tori -' ls used were representative of those commonly used

in building construction. Tnj bricks were selected to cover a wide

range in both the rate and amount of absorption for brick used in ex- posed structures. One type of brick had a very low, one a medium and

oue tnird a very hign ana rapid absorption. These three types are designated in Table 1 as a, b, and c, respectively.

a group of 48 brick walls included specimens both 8 and 12 inches

thick, using three kinds of brie]; (see Table 1), 4 cement-lime mortars

and two classes of workmanship in various combinations.

Six different types of structural clay tile and one kind each of

stone and cinuer concrete block were faced with either stucco or ith

brick (b). All walls of hollow masonry units (Table 2) were built with

a single cement-lime mortar. The five mortars used were designed to

determine the relative permeability of walls with high—lime or high—

cement mortars; the effect on p enaeabi 1 iby of integral waterproofing, and of differences in wader retaining capacity. Physical properties of

these mortars are given in Table 5.

121537-K
The stucco used as a facing for the 8 walls of tele (j) was mixed

in the proportions by weight of one part of Portland cement to three

parts of sand; volume proportions were one part cement to about 3.5

parts of loose damp sand. The water added to each hatch was about 8.5

gallons per sack of cement. After applying the stucco to the walls

they were thoroughly wetted once a day for several days.

Walls of workmanship A were solidly built. The bed joints were spread to a uniform thickness and the cross and collar joints were care- fully filled. Face joints were tooled with round steel bars.

workmanship B was of a type commonly used for contract construction. Interior joints of the wall were ojjen ana a minimum amount of

mortar was used. Face joints were cut.

After completion, the walls were allowed to stand in the laboratory for two or three days without being moved. The walls were then

whitewashed on the ends and back and placed in the drying rooms. After one month or more, depending upon the time required for drying,

the wails were given the first permeability test. They were also dried

thoroughly between successive tests.

Table 1 - PHYSICAL PROPERTIES OF BRICK

•:Type

0•

•

•

Average dime

width: Length

)nsion:-vvg.

Bopth : dry

Absorptioi

total imine]

5 hr: 48 hr

cold: cold

i by : Time requir,

r-sion: total ponet:

5 hr: by capillary

boil: Flat: Edge

2 d for : ;ation : action:

End :

••

•

: (a)

: (b)

: (

c

3.75: 8.00

3.60: 7.75

3.95: 8.20

2.25: 5. 21

2.15:4.35

2.30:4.76

per-: percent: cent

0.4: 0.6

7.7: 9.1

15.9:16.8:

per-: hrs.: hrs.

cent: : 1.6: — : —

11.4: 0.40: 1.9

18.8: 0.12: 0.32

«

•

••

12.5 : 1.8 :

2
Table 2 -PHYSICAL PROPERTIES OP STRUCTURAL

CLTCy .PILE hollo.* COHCRETE BUILjILG UNITS

Masonry unit

Dry

wt

.

absorption by

24 hr s cold

immersion

Absorption : by 1 hour : boil : lb. percent ILyfi'S percent :

: (d) Double shell,

6 cells

33 .

3

2.8 3.9 :

: (e) Side construnion, 3 cells

15.

S

5.7 — 8.1 :

! (f) Speed-a-3acker 22 .

5

4.1 - 7.1 :

: (g) Raritile,

4 'cells

25.8 10.6 — 14.6 :

: (h) Techwood,

6 cells

33.7 10.4 — 13.3 :

: (j) Standard,

6 cells

34.1 4.1 6.3 :

: (m) Stone concrete

blocks

,

2 cells

29.9 8.9 10.8

: (n) Cinder concrete

block, 2 cell

21.9 16.2 13.3 — •

Table 3 - PHYSICAL PROPERTIES OF MORTARS

Mortars

Proportions of sAvg

edment, lime & sand: ten- By vol . : 3y dry wt . : wt

.

1 1:0.25: 3:1:0.11:2.6:

2 1:1:6 :1:0. 42:5.1:

3 1:2:9 : 1:0. 85: 7. 7: 4 1:1:6 :1:0. 42:5.1:

5 1:1:6 : 1 : 0 . 42 : 5 . 1

water con- percent by

f dry mtls.

Compressive

strength in

28 days

Flo** aft

suction'

lb/irk' percent

19.3 2850 86

22.6 640 95

23.7 250 97

22.7 550 95

19.8 950 30

(l) .^ater retaining capacity lay the method of Federal Specifications

3S-0-181a

3

0>r-»
Capillarity tost: This was the first tost applied to each wall.

The wall was supported in a vortical position and water applied near

the top of the exposed face "by moans of a perforated metal pipe, re- sulting in a thin shoot of water running down the face of the wall.

In this tost the water penetrated the walls under the. forces of capillarity and gravity only.

Heavy-rain test: The conditions of exposure simulated the. effect

of a wind storm accompanied hy heavy rain.- The wall was clamped into

position so as to form on 3 side of an air-tight pressure chamber, the

joint 'between the wall and the' chamber "being made air-tight by means of

a sponge rubber gasket. The air pressure erf 10 lbs/sq ft produced a pressure gradient within the wall from face to back.

Light-rain test: These tests- ..ere made only on some of the walls

that had been found most permeable in the heavy-rain tests. The test

differed from the heavy—rain test -only in the amount of water applied

and in the method of application, which was by means of atomizers in

amounts equivalent to 0.2 in/hr/sq’ ft of v/a'll surface.

I&TING-S

'

Since- it was desirable to: classify the walls according to their

comparative resistance to penetration by water, an arbitrary system of' rating was established. The backs of tire walls were not plastered and

the high relative humidity in the testing room prevented the drying

which would occur on the interior surface of wails in heated buildings.

The ratings of the walls were as follows:

Excellent (li) : walls ha-ving no leaks through either the wall or the facing withe, and less than 25,o of the wall area damp in 7 days.

Good (G )

halls having no leaks through either the wall or facing

withe, and less than 50)o of the wall area damp in 1 day.

Fai r ...alls having 50/a or more of the wall are., damp in 1 day,

or having a leakage through the wall or facing of less than 1 litter of

water per hour.

Po or , I’P)

Walls having a 'leakage of less than 1 liter of water per

hour through the wall ana less than 15 liters of water per hour through

the facing during the first day.

Very poor (V.P. ) : Walls .raving a leakage of more than 1 liter of

water per hour through the wall, or more then 15 liters of water per

hour through the facing.
RESULTS OF JUS TS OK BRICK WALLS

The results of the wall tests in general were consistent enough to

indicate at least the relative advantages or disadvantages of different

workmanships, kind or combination of brick, kind of mortar and of wall

thickness. Kuarly .11 the walls, on which it was necessary to make re- peated tests of the same kind, showed a decrease in permeability.

Comparative performance of all-brick walls under capillarity and

heavy-rain tests, with the capillarity test taken as unity, gave the

data shown in Table 4.

Additional data from the light rain tests on the more permeable

walls indicated that it took about 50 times as long for dampness to

penetrate the wall during a light-rain tost and about 200 times as long

for the appearance of leakage through the facing than was required for

the heavy- rain tost.

Table 4

«• .»orkrnan- Relative time for Relative area Relative :

: Brick ship and penetration as damp after amount of:

thickness indicated by: 1 day 1 eakago : Dampne s s Leakage

•

*

•

• 8 in. A 0.07 1.4 _ ;

: (a) 12 in. A 0.25 - 1.0 :

•

• 8 in. B 0.29 0.45 _1.1 3.1 :

•

• 12 in. B 0.14 0.13 1.1 2.7 :

•• 8 in. A 0.05 0.01 1.0 3.1 :

: (b) 12 in. A 0.04 — 1.6 - :

•

• 8 in. B 0.45 0.21 1.0 3.6

•

%. W ~t 12 in. B O.OS 0.02 1.3 5.9 :

•• 8 in. A 0 . 54 0.08 1.1 4.0 :

: (c

)

12 in. A 0.18 — 1.6 - :

•

• 8 in. B 0.30 0.03 1.0 2.9

12 in. B 0.29 0.05 1.1 4.1

The results of the tests showed that workmanship was the most important factor affecting th.; permeabilit;/ of brick walls of common American bond. The best performance was obtained when the interior

joints were well filled and the face joints wore tooled (workmanship A).

Walls with tooled face joints were mor-‘ resistive than similar specimens

with cut joints, but the filling of the interior joints was of greater

benefit than tooling of the face joints. In the case of workmanship A,

the least permeable walls W3re those built of the least absorptive brick,

whoreas the absorptive properties of the brick had little effect on the

performance of tho more permeable walls of workmanship B.

- 5 -
Varying percentages of lime and c oniont in tho mortar had only a . . u very small effect upon the water permeability. Tuo walls with mortar

number 1 (high cement-low lime) wore slightly loss permeable than those

with mortars of greater lime content. The addition of a metallic stearate to one of the mortars (ho. 4) iud little effect on the permeability.

The substitution of a non-plastic lime for the highly plastic putty used

in mortars 1 to 4 inclusive, had a much greater effect than changes in

the relative proportions of lime and cement, 'Tails constructed with the

1:1:6 mortar containing non-plastic lime (mortar 5) showed significantly

inferior performances to those built with the other mortars. Those re- sults indicate that the permeability of the masonry depended much more upon the water retaining capacity of the mortars than upon the lime-cement

ratio. The relative working properties of mortars of low and high water

retaining capacities wore noted by oho masons who expressed satisfaction

with tho working properties of mortars 1 to 4, but who commented on the

difficulty of using mortar 5, particularly when laying bricks having a high suction (high absorptive brick in a dry condition).

'wetting high absorptive brick before laying resulted in the con- struction of walls of much lower permeability than was the case, when tho

brick wore laid in a dry condition. The effects of water content or suction of the brick wore greatest for workmanship A.

resul ts op tests oi; tails .. ith hollo >/ strjctqbal units

The performance of the walls with a backing of hollow units was affected more by the p ermeability of the facing than by any other factor. The walls of workmanship 3 leaked considerably at the bottom and

the cells in the lower courses wore partially filled with water. However, on the average, the performance of those walls was not much different for typical 12-inch walls of brick and workmanship B. The walls

of hollow concrete units were very permeable, irrespective of workmanship.

The walls constructed with two fr-inch facing coats of stucco on a backing of 6-cell 3 x 12 x 12-inch clay tiles were the least permeable

of all walls containing hollow masonry units. f.uo data on performance

of the stucco walls, in the heavy-rain tests, are given in Table 5.

6
Tatis 5 - PERFQRLLAKGE 0? WALLS WITH STUCCO FAG IhGS

( Ilea'vy-ra in t -3 s t s )

: Cons true

: tion of

jwalls (i)

•

•

hura-:Time to fail e tion : Damp

of : through

test : wall

« days : hours

•

: E-p-a 4 : 87|e

: E-p-r 3 : 4144

: E-w-s 14 : 2074-5

• E-w-r 6 : 6445

: S-p-s 6 : 1084-7

: S-p-r 7 : 1324-7

: S-\7-s 7 : 1424-14

: S-w-r 6 : 1274-'

indicated by

Leak

through

wall

Area

damp

at end

of test

Max.

leakage

per

hour

Rating:

hours p or- cent

liters

- 55 0 G : — 8 0

n

at ; — 23 0

*rrr ill - 33 0

' G ; — 17 0 E : — 25 0 E : — 10 0 E : — 17 0 JLe l

(1) Key for cons traction symbols: : E - tils set on end. :S - tile set on side.

p - plain stucco. :w - water-proofed stucco

s - smooth texture on finish coatsr - rough texture on finish coat

SURFACE V/ATERPROQF IK

G

JFokTxFJMTS

In order to determine the effectiveness of waterproofing methods

for leaky masonry wails in existing structures, several of the walls

which leaked in the permeability tests were treated and then retested.

Three treatments wore used, classified as:

1.

Baking the face joints and ropointing with mortar.

2. Filling openings in the face of the wall (especially in the

joints) with cement-grout or wax.

3. Painting the wall with colorless solution, or oil paint or ce- ment paint.

Some, of the treatments were combinations of these and one was a molten paraffin treatment. Ropointing of the face joints was suffessful in that the permeability of nil the walls was greatly reduced. The

permeability of the brick (c) walls was not reduced as much, because

the r ’pointing operation did not affect the absorptive properties of

the brick.

The use of colorless '..'at rproofing solutions containing paraffin

with tung oil or aluminum stearate and limbi effect on the permeability
of walls that leaked through openings in the joints. These solutions were somewhat effective when used on walls that had 'been penetrated by

moisture through capillary attraction.

Two kinds of joint filling materials were used; a wax, and finely

divided cementitious mixtures. The performance, of the walls was improved by waxing the joints, the average rating being increased two

grades from V.P. to F. The paraffin wax in the joints altered (and possibly marred) the appearance of the walls because of irregular accentuation of the joints. Grouting of joints with a mixture of 40% high-earlystrength cement; 15% ppwdcred flint, and 45% Potomac River building sand

greatly reduced the permeability of the walls.

Painting of the exposed surface of walls with either oil or cement

paints was markedly effective on walls that had previously been very

permeable, irrespective of whether the water had penetrated the walls

through openings in the joints or by capillary action. Cement paint applied to walls of concrete masonry 'units (workmanship A) raised the rating of these walls from very poor to good.

CONCLUSIONS

Workmanship affected the permeability of the walls more than any

other factor. Walls with tooled joints were less permeable than similar

walls with cut joints; but the quality of the workmanship within the

walls had a greater influence than the kind of surface finish on the

joint.

The effect of wall thickness on the relative permeability of 8-inch

and 12-inch brick walls was such that it required several hundred times

as long for moisture to penetrate thu thicker walls of workmanship A,

and six times as long for the penetration of 12-inch walls as for the 8-

inch walls of workmanship B.

The absorptive properties of the brick had a greater effect on the

permeability of walls of workmanship A than on walls of workmanship B.

The least permeable walls. of workmanship A were those built with the low

absorptive brick. Walls built with high-cement, low-lime mortars were slightly less permeable. Pke use of a lime of low plasticity producing

a mortar with low water retentivity greatly increased the permeability

of the walls. This effect was more pronounced when the mortar was used

with high absorptive brick. Wetting high absorptive brick before laying

reduced the permeability of the walls, especially for workmanship A.

Walls with a brick facing and a backing of hollow units were about

equally as permeable as all-brick walls of similar workmanship.

’Walls with a structural clay tile backing and a stucco facing were

less permeable than walls f^ced with a medium absorptive brick.

__ Q _
All of tlie joint treatments sach as repointing, grouting, or filling the joints with a paraffin wax were effective in stopping leakage

through openings in the face joints. The appearance of walls was altered and possibly marred by the paraffin wax in the joints. Molten

paraffin, oil paint and cement paint were effective waterproof coatings.

DURABILITY 07- BUILDING MATERIALS

TIBM 59 and TIBM 60

The investigations relating to the durability of some loose-fill and aluminum foil insulating materials, and the

corrosion of ferrous metals used in house construction were undertaken at the National Bureau of Standards primarily

for the guidance of Federal agencies engaged in housing.

In order to afford adequate time for review of the

facts and to bring the investigations to a final conclusion,

the tentative reports (TIBM 59 and TIBM 60) relating to the

preliminary studies are being withheld from general distribution.

However, the investigations of the properties and suitabilities of various types of building materials, including

those outlined in TIBM 59 and TIBM 60, are. being carried on actively at the National Bureau of Standards, and the re- sults of these investigations will be made available in permanent form as soon as the various stages of the work can be

completed.

U/U/30