NATIONAL BUREAU OF STANDARDS REPORT

9014

WATER PERMEABILITY OF LATEX EMULSION COATINGS ON

CONCRETE MASONRY

by

L. F. Skoda and J. 0. Bryson

Report to

Office of the Chief of Engineers

Bureau of Yards and Docks

Headquarters , U.S. Air Force

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

421.00-12-4212401 December 30, 1965 9014

WATER PERMEABILITY OF LATEX EMULSION COATINGS ON

CONCRETE MASONRY

by

L. F. Skoda and J. 0. Bryson

to

Office of the Chief of Engineers

Bureau of Yards and Docks

Headquarters, U.S. Air Force

IMPORTANT NOTICE NATIONAL BUREAU OF STAN

for use within the Government. Be

and review. For this reason, the pi whole or in part, is not authorizec Bureau of Standards, Washington, C the Report has been specifically pre

iccounting documents intended Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

jected to additional evaluation

ting of this Report, either in

‘fice of the Director, National

e Government agency for which

s tor its own use.

NBS,

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
- .!
Water Permeability of Latex Emulsion Coatings on

Concrete Masonry

by

L. F. Skoda and J. 0. Bryson

ABSTRACT

Three waterproofing systems applied to concrete masonry

walls were tested for permeability. The object of these tests

was to determine the effectiveness of waterproof coatings that

require only an air dry cure. The walls treated with one-and

two-coat systems of polyvinyl acetate, acrylic and styrene

butadiene latex emulsions were alternately tested and allowed

to weather over a period of 5 years. The range of ratings re- sulting from these tests varied from the one-coat styrene butadiene wall which received a very poor rating prior to weathering to the two-coat acrylic wall which received an excellent

rating after over 5 years exposure to weathering.

I. INTRODUCTION

As requested by participating agencies of the Tri-Service

Program, The National Bureau of Standards makes specific investigations of properties of building materials, equipment and

structural assemblies. The test program for water permeability

of latex emulsion coatings on concrete masonry was formulated in

consultation with representatives of the Office of Chief of Engineers U. S. Army. The original test program was to include tests of

one-coat and two-coat systems of polyvinyl acetate and acrylic

emulsion coatings. At the request of the U Q S. Air Force a third

material, styrene butadiene latex emulsion, was added to the materials

under study.

For the past 30 years cement based paints have been used to

stop leakage of rain through concrete masonry walls. For proper

application of these paints, the wall must be moistened prior to

painting and the coatings must be subsequently moist cured. Under

certain conditions, such as in windy and arid locations, proper moist

curing is difficult to achieve. This investigation was intended to

evaluate the effectiveness of sanded cement base paints mixed with

polyvinyl acetate, acrylic or styrene butadiene latex emulsions when

applied to masonry walls without subsequent moist cure. The use of

paints which are effective in stopping leakage through concrete masonry,

will result in more economical treatment of leaky walls under adverse

conditions

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II. PROCEDURE 2.1

Test Walls

Six permeable concrete masonry test walls were built to

accomodate the testing of the waterproofing materials. The walls

were approximately 8-in. thick, 40-in. long and 50-in. high. The

masonry units used in the walls were autoclaved, cinder concrete,

hollow load bearing units with a nominal size of 8-by 8-by 16 inches.

The mortar used contained 1:3 parts by volume of Type II masonry

cement and masonry sand. The walls were constructed by an experienced mason and the workmanship used was that commonly found in a well constructed concrete masonry building.

2.2 Waterproofing Materials

Mixing liquids and finish paints were supplied in sufficient

quantity to meet the needs of the test program by the following

manufacturers: The Dow Chemical Company; National Starch Products

Inc,; Rohm & Haas Company. The materials were tested for quantitative requirements as outlined in the Interim Federal Specifications

designated TT-P-0019a, TT-P-005a and TT-P-0099a dated May 21, 1958.

All material met the prescribed requirements.

2.3 Application of Coatings

Two wall specimens were used for the tests of each material.

Both walls of each set received a fill coat in the proportions outlined in the Interim Federal Specifications noted above 0 One of the

two walls in each set received an additional coating of finish paint.

The procedure used in applying the fill coat to all walls was

essentially the same. The walls were thoroughly dampened one hour prior

to application of the coating. The fill coat was scrubbed into the walls

with an ordinary fiber bristled scrub brush. The waterproofing mixture was

stirred periodically during application to insure against settlement of

the cement and siliceous material.

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The fill coat was allowed to air dry at 75®F and 507, R.H 0 for

at least a week prior to application of the finish paint 0 The finish

paint was applied with a 4-in. paint brush. The volumes and weights

of all materials used were recorded before and after application so that the spreading rate could be determined.

2.4 Test Apparatus & Testing

The test apparatus simulates exposure to a heavy rain, driven

by a 50-mph wind. The treated face of a test wall forms one side of

a pressure chamber. Water at the rate of 40 gal/hr is applied to the

top of the exposed face from a tube containing a line of small holes

spaced 3/4 in. apart 0 Air pressure within the chamber is maintained

at 10 lb/ ft2 above atmospheric pressure, equivalent to a hydrostatic

head of 2 in. The test is conducted for a minimum of 24 hours and

until the best possible rating is achieved.

The test sequence is the same for all walls. The initial permeability test is performed on the untreated wall. The wall is then

allowed to dry to constant weight prior to application of the waterproofing materialo The test is then repeated on the treated wall.

Following this test the wall is moved to an outdoor exposure site for

subjection to weather ing„ At yearly intervals the wall is returned to

the laboratory, allowed to dry to constant weight and then retested.

This procedure is repeated until the performance rating is significantly reduced.

2.5 Permeability Ratings

The water permeability test ratings are listed below:

Excellent (E) - No water visible on back of the wall

(above the flashings) at the end of 1 day. Not more than

25 percent of the wall area damp at the end of 3 days.

No leaks \J through the wall in 3 days.

Good (G) - No water visible on the back of the wall at the

end of 1 day. Less than 50 percent of the wall damp at the

end of 1 day. No leaks through the wall at the end of 1 day.

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Fair (F) - No water visible on back of the wall during

first 3 hours, but visible at the end of 1 day. The rate

of leakage through the wall less than 1 liter/hr at the

end of 1 day.

Poor (P) - Water visible on back of wall in 3 hr or less

and at the end of 1 day. Rate of leakage through the wall

less than 5 liter/hr at the end of 1 day.

Very Poor (VP) - Rate of leakage through the wall equal to

or greater than 5 liter/hr at the end of 1 day.

Water-resistant coatings applied to permeable concrete masonry

should preferably have permeability ratings of Good or Excellent.

Coatings rated as Fair may possibly be considered to have a satisfactory resistance except when subjected to rain with winds

of high velocity.

Coatings rated as Poor and Very Poor would be expected to have

an unsatisfactory resistance to the penetration of wind-driven rain.

— Leaks are defined af follows: A leak is a flow of water from one or both flashings, the combined rate of flow being equal to or greater

than 0.05 liter/hr.

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II T. RESULTS

3ol Spreading Rates

The spreading rates for the fill coats and finish coats of the

three materials that were tested are given in Table I Q The spreading

rates for the polyvinyl acetate and acrylic emulsion systems are comparable for both the fill coat and finish paint treatments. The

spreading rate of the fill coat for the styrene butadiene is considerably higher than the others because the liquid portion of the

solution was incapable of holding the cement and sand in suspension.

During application of this fill coat the solution was continuously

mixed but very little of the cement and sand was brushed into the

wall (No. 6). Consequently, when the finish paint was applied to

wall No. 6 the spreading rate was somewhat less than that of the

other materials as the finish paint had to fill voids that were not

filled by the fill coat.

3.2 Permeability Tests

The results of the permeability tests are given in Table II.

There was no significant difference in the tests of the untreated

walls o This indicates that the materials of construction and the

workmanship were the same for each wall.

The determination of visible water on the back of walls numbered

2 & 3 at 2 0 7 & 3.2 years exposure occurred sometime between 5 P. M. of

the first day of the test and 9 A. M0 of the following day. The apparatus used for the permeability test is capable of operating unattended, but visual observations were only made during the working day.

The ratings of these walls were not affected by this inaccuracy because

the visible water occured more than 3 hours after the start of test and

no flashing leak was evident.

An examination of the rating column in Table II indicates that

walls numbered 1, 2 and 5 received better ratings after a number of

years of exposure than after brief periods of exposure. This phenomenon

is not unusual and has been evidenced in other test programs. This

improvement in rating is attributed to the accumulation of dust, dirt

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and other foreign matter (as a result of weathering) on the wall

surface and particularly in the voids and cracks that cause penetration and leakage of water.

3.3 Discussion of Results

Of the three materials tested, the two-coat acrylic emulsion

treatment was the most successful. After more than 5 years of ex- posure to weathering this wall withstood the penetration of wind

driven rain for 5 days with only a small area of the wall becoming

damp. In every other case where the test wall received on initial

acceptable rating (Fair or Good) the rating was reduced with time.

The styrene butadiene treated walls had a rating of Poor at best.

This is understandable in light of the relatively greater spreading

rate of the fill coat of styrene butadiene.

IV. CONCLUSIONS

a) it is possible to waterproof a highly permeable masonry wall

with latex base waterproofing compounds thereby eliminating the

necessity for any kind of curing other than air drying.

(2) Of the three materials tested the two coat acrylic emulsion system

was superior to the other systems.

(3) All systems with initially acceptable ratings (other than the two

coat acrylic) were reduced in rating after the initial exposure period.

(4) The improvement of the permeability rating after an extended period

of time is attributed to the accumulation of foreign matter in the voids

of the walls due to weathering.

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TABLE I. SPREADING RATES

Wall No.

Water Proofing

Material

Type of

Coating

Spreading

Ft. 2

/ K,

1 Polyvinyl Acetate Fill 64

2 M II Fill 68

2

II II Finish 160

3 Acrylic Fill 60

4

ii Fill 50

4

ii Finish 171

5 Styrene Butadiene Fill 204

6

ii ii Fill 204

6

ii ii Finish 137

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Table II Permeability Test Data

Time to Failure as

Wall Condition Duration Indicated Max. Area

NOo of of Test Damp Visible Flashing Rate Damp Rat ing

wa 1 1 <days on Water of at End

Back on back Leak Leakage of Test

hr hr hr L/hr 7o Untreated 1 0.05 0 o 13 0.10 28,9 91 VP

PVA Fill Coat 1 1.16 5.53 14,53 0.1 80 F

lo5 yrs Exposure 1 0.33 1.05 0.73 14.4 95 VP

n 2 0 7 yrs Exposure 1 0 o 75 lo 52 None None 85 P

3 0 6 yrs Exposure 1 0.62 1.08 None None 90 P

4.7 yrs Exposure 1 0,40 0.80 None None 83 P

5o7 yrs Exposure 1 0,40 0 o 70 None None 92 P

Untreated 1 0.06 0 o 08 0,10 30,6 97 VP

PVA Fill Coat &

Finish Paint 5 3 o 00 30 o00 None None 35 G

1 0 5 yrs Exposure 1 2.00 4,00 None None 83 F

n 2.7 yrs Exposure 1 0,51 14. 5±8 None None 80 F

3 0 6 yrs Exposure 1 0.65 2.32 None None 85 P

4o7 yrs Exposure 1 0.57 2.70 None None 30 P

5.7 yrs Exposure 1 0.68 3.67 None None 67 F

Untreated 1 0.08 0.08 0.08 20.4 97 VP

Acrylic Fill Coat 5 3.00 90.00 None None 37 G

1.1 yrs Exposure 1 1.85 7.65 None None 63 F

#3 2.3 yrs Exposure 1 3,36 6 0 55 None None 27 F

3.2 yrs Exposure 1 3 , 50 14,5±8 None None 40 F

4 0 3 yrs Exposure 1 3 o 20 6.48 None None 17 F

5o4 yrs Exposure 1 3.25 6,02 None None 40 F

Untreated 1 0.07 0.10 0.08 26.40 98 VP

Acrylic Fill Coat

Sc Finsih Paint 5 72o00 None None None 2,6 E

1.1 yrs Exposure 5 6.80 None None None 3.3 E

n 2.3 yrs Exposure 5 22.70 None None None 7 o 0 E

3,2 yrs Exposure 5 7.12 None None None 35.0 E

4.3 yrs Exposure 5 22o90 None None None 23,0 E

5 0 3 yrs Exposure 5 23 „ 20 None None None 17.0 E

Untreated 1 0.02 0,02 0,02 44.4 88 VP

:t5 Sty. Bute Fill Coat 1 0.32 0,32 0.33 31.2 90 VP

1.2 yrs Exposure 1 0.11 0.15 0.15 1.56 95 P

u

Untreated

Sty. But. Fill Coat

& Finish Paint

1 0 2 yrs Exposure

1 0.03 G.03 0.06 44.4 90 VP

1 0.48 1,13 1.30 1.2 87 P

1 0.25 0.28 0.28 1,8 88 P
* . • . .