NATIONAL BUREAU OF STANDARDS REPORT

8009

SECOND PROGRESS REPORT

ON

BONDING TO TREATED CONCRETE SURFACES

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards arc set forth in the Act of Congress,

March o, 1901, as amended by Congress in Public Law G19, 1950. These include the development and maintenance of the national standards of measurement and the provision ol means

and methods for making measurements consistent with these standards; the determination of

physical constants and properties of materials; the development of methods and instruments

for testing materials, devices, and structures; advisory services to government agencies on

scientific and technical problems; invention and development of devices to serve special needs

of the Government; and the development of standard practices, codes, and specifications. The

work includes basic and applied research, development, engineering, instrumentation, testing,

evaluation, calibration services, and various consultation and information services. Research

projects are also performed for other government agencies when the work relates to and supplements the basic program of the Bureau or when the Bureau’s unique competence is required.

The scope of activities is suggested by the listing of divisions and sections on the inside of

the back cover.

Publications

The results of the Bureau’s research are published either in the Bureau’s own series of

publications or in the journals of professional and scientific societies. The Bureau publishes

three periodicals available from the Government Printing Office: The Journal of Research,

published in four separate sections, presents complete scientific and technical papers; the Technical News Bulletin presents summary and preliminary reports on work in progress; and the

Central Radio Propagation Laboratory Ionospheric Predictions provides data for determining

the best frequencies to use for radio communications throughout the world. There are also

five series of nonperiodical publications: Monographs, Applied Mathematics Series, Handbooks.

Miscellaneous Publications, and Technical Notes.

A complete listing of the Bureau’s publications can be found in National Bureau of Standards Circular 460, Publications of the National Bureau of Standards, 1901 to June 1947 ($1.25),

and the Supplement to National Bureau of Standards Circular 460, July 1947 to June 1957

($1.50), and Miscellaneous Publication 240, July 1957 to June 1960 (includes Titles of Papers

Published in Outside Journals 1950 to 1959) ($2.25); available from the Superintendent of

Documents, Government Printing Office, Washington 25, D.C.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

1004-12-10449 30 June 1963 8009

SECOND PROGRESS REPORT

ON

BONDING TO TREATED CONCRETE SURFACES

by

Winthrop C. Wolfe

%

Organic Building Materials Section

Building Research Division

0*

Sponsored by

Office of the Chief of Engineers

Department of the Air Force

Bureau of Yards and Docks

IMPORTANT NOTICE NATIONAL BUREAU OF

for use within the Governmen

and review. For this reason, whole or in part, is not aut Bureau of Standards, Washii

the Report has been specifics

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

iress accounting documents intended

is subjected to additional evaluation

jre listing of this Report, either in the Office of the Director, National by the Government agency for which

il copies for its own use.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

SECOND PROGRESS REPORT

ON

BONDING TO TREATED CONCRETE SURFACES

1 . INTRODUCTION

The subject of bonding to treated concrete surfaces is a broad one. Concrete

can be treated with curing and parting agents., chemical ’'hardeners", sealers,

and other treatments. The concrete surface can be finished with a variety

of organic coatings and coverings. The present work was mostly on vinyl

asbestos tile, laid with asphalt cutback or asphalt emulsion adhesive on

concrete treated with curing and parting agents. Parting agents are used

with lift-slab and tilt-slab construction and are not of great importance

at present. The term "curing agents" generally refers to organic coatings

applied to fresh concrete to seal in the moisture and allow the concrete to

cure. The main problem to be investigated was the adhesion of vinyl asbestos

tile, applied with asphaltic adhesive, to concrete floors. Specifically, it

is important to know how to lay tiles on old floors and how to treat new

floors so that tiles can be applied. The problem with old floors is to

determine what treatment, if any, is necessary to enable tile to be laid

satisfactorily. In the case of new floors, specifications should be written

such that the floors will be suitable to receive tile.

Resilient floor coverings are not suitable or necessary for some purposes

and some buildings are constructed with the intention of leaving concrete

floors bare or painted. In such cases, oily or waxy curing agents may be

left on the floor, the floors may have been painted, waxed, or both, or there may be an accumulation of oil, grease, and dirt on the floors.

Materials such as oils and waxes on the floor are known to cause poor

adhesion of resilient tiles. The problem would be simpler if the previous

history of each surface were known, but this is not always the case. In

the past, specifications have banned application of resilient floor coverings if oily or waxy materials or any membrane curing compounds had been

applied to the floor. Apparently the only remedy was costly grinding or refinishing. It would be desirable to have a field test to determine

whether a floor was suitable to receive resilient tiles and what, if any,

treatment was necessary. This might be a test for adhesion of tiles or

an analysis of the surface coating.

As already mentioned, membrane curing compounds in general have been

prohibited on concrete floors which are to receive resilient floor coverings.

This attitude is gradually changing as reliable products become known and

progress is made in the relatively new field of membrane curing. Accordingly

specifications are in the process of change.
.

1
- 2 -

The work reported here was undertaken with the above considerations in

mindo An attempt was made to develop a field test which would be simple,

reliable, and as rapid as possible. A good field test could be used to

determine whether tile can be laid satisfactorily on a concrete floor and

also as a part of specifications for membrane curing compounds and for

concrete work. Some work was done on the analysis of concrete surfaces

for oils and waxes and an attempt was made to evaluate concrete surfaces

for wettability. Several widely used commercial curing and parting agents

were analyzed and further information on the composition of such materials

obtained from the Bureau of Public Roads. This provided information about

the kind of materials currently used for this purpose. Analytical data

was used to prepare known formulations which were tested along with

commercial curing agents. Although a suitable field test has not been

developed, some progress has been made towards a laboratory test which

might be used as a basis for a qualified products list. Also, knowledge

has been gained from the tests to enable more satisfactory decisions

regarding the tiling of old concrete floors.

2. FIELD INSPECTIONS

Manufacturers of curing compounds have cited a large number of cases in

which their products were used to cure concrete floors with subsequent

satisfactory installation of resilient tile. As mentioned in the previous

report, a number of buildings were inspected, the concrete floors of which

had been cured with "West Concrete Floor Treatment", then successfully

tiled. Another large building in Washington was inspected two days after

the ground slab was poured. The floor appeared yellowish gray and had a dull sheen, obviously from a transparent coating. There were some unopened

drums of "West Concrete Floor Treatment", which the superintendent said was

part of a shipment which had been used to coat the floors. Construction work

was proceeding on the "green" slab. A year later the completed building was

inspected. In the meantime, asphalt tile had been applied, using bentonite

clay type asphalt emulsion adhesive. The tile appeared to be in perfect

condition and the maintenance staff said that there had been no loose tiles

or other complaints about the flooring.

A small building in Washington was inspected while the ground slab was

poured and hard troweled and "Toch RIW Seal Cure" applied, using a lamb's

wool applicator. The completed building was inspected a year later.

Vinyl asbestos tile had been applied, with asphalt emulsion adhesive. The

tile installation appeared to be satisfactory with no loose tiles.
v i"
- 3

-

A building in Arlington was erected by the lift-slab method; using Thompson’s

Water Seal as the parting agent c After about six months; the uneven first

floor was refinished with a terrazzo grinder . About 10 percent of the upper

three floors was refinished with a grinder 0 Asphalt tile was laid on the

floors; using asphalt emulsion adhesive. After about a year,, the building

was inspected again. The tile installation was reported to be satisfactory

throughout. Adhesion of tiles was so good that it was difficult to remove

damaged tiles.

3. LABORATORY ADHESION TESTS

A number of qualitative adhesion tests were run on panels arid slabs of

concrete,, 1/2 to 5/8 inch thick; made from 2 parts port land cement,, 6 parts

of concrete sand,, and 1 part of water* by weight,, Sometimes slightly more

water was added to make the mix workable,, depending on the water content

of the sand. This proportion was used in tests described by Percy A. Sigler

and Robert I„ Martens,, Building Materials and Structures Report BMS 59,

National Bureau of Standards,, September 19,, 1940 ? ""Properties of Adhesives

for Floor Coverings*" . Most of the panels were 4-1/2- by 9-inches or half

the size of a standard 9- by 9-inch vinyl asbestos tile. Some of the panels

were 6- by 6 -inches and a series of seven 27- by 28-inch slabs was prepared

for nine 9- by 9-inch files each; leaving a 1- by 27-inch strip for marking.

One of the 27- by 28-inch slabs or a set of eighteen 4-1/2- by 9-inch panels

weighed about 29 pounds.

The object of the tests was to evaluate various concrete curing agents for

adhesion of floor covering cement and to devise a suitable test method for

evaluation. According to the ““Bond Test"8 on page 34 of Technical Data,,

1962-63^ Armstrong Cork Company,, 3- by 3-ft. panels of the flooring material

to be used are installed approximately 50 feet apart on the floor. Panels

are checked for bonding or adhesion after two weeks. In NAVDOCKS Specification 13Yf, December I960; p. 12; under 2.13.7; Liquid chemical compound , a simple; quantitative adhesion test is described. In this test; concrete

slabs are prepared; cured; dried; and floor covering applied in the normal

manner. After the adhesive has set; cuts; an inch apart and 6 to 10 inches

long; are made; forming strips to one end of which a calibrated spring

balance or other device is attached. The strips are peeled off at a rate

of 2 to 10 inches per minute. Adhesion to concrete treated with curing

agent must be at least 90 percent of adhesion to the same concrete untreated.

The test method used in the present work was to first apply curing agents

to the "“green** or fresh concrete in a manner similar to that which would

be used on actual floors. In similar tests performed elsewhere; precast

concrete blocks are sometimes used and the blocks are soaked in water for

24 hours before applying curing agents. Untreated panels were steam cured

for 28 days. Treated panels were placed in a constant temperature, constant

humidity room at about 73°F., 50% relative humidity. Before applying floor

coverings, the steam cured panels were allowed to dry in an ordinary room

for several days. After curing, the panels were coated with suitable adhesive

cements and appropriate floor covering materials applied. Most of the tests

were made with vinyl asbestos tile, using asphalt cutback and asphalt

emulsion adhesive. Some tests were performed using linoleum and linoleum

paste. Since tests with floor coverings are slow, an attempt was made to

devise a quicker test, using cotton gauze strips in place of floor covering.

It was thought that the cement would dry faster and simulate a longer period

of time.

The gauze strip test was based on a method for testing the adhesion of paint

films, reported on page 176 of Henry A. Gardner and G. G. Sward, ’’Physical

and Chemical Examination of Paints, Varnishes, Lacquers, and Colors”,

Henry A. Gardner Laboratory, Bethesda, Md., 11th ed., 1950. This method is

called the ’’Gardner Laboratory Adhesion Method”. Figure 266 in this book

shows the ’’Gardner -Parks tensile strength meter adapted for quantitatively

determining the adherence of films”. Apparently this refers to the ’’Gardner

Tensile Strength and Elongation Apparatus 8 , Catalog No. TG-1500, Gardner

Laboratory, Inc., P. 0. Box 5728, 5521 Landy Lane, Bethesda 14, Md., priced

at $603.75. The test method was based on preliminary work by a committee

of the ASTM. A film of the coating material is applied by any suitable

method to a panel about 3- by 5-inches. A piece of silk cloth is then

placed upon the film while it is still in a tacky condition and pressed

firmly in contact with the base panel by means of a broad, flat spatula.

After further drying for any desired period of time, the surface is cut

up into areas 1 cm. wide by means of a sharp razor blade. Each test panel

is then fastened into the tensile strength apparatus as shown in the illustration and one of the strips is partly removed at the top of the panel in- order to form a grip for the machine. By applying the load, the strip is

slowly and gradually removed from the coated panel. The load usually is

constant for the entire length of the panel, thus showing that the adhesion

is the same over the entire surface where normal conditions obtain.

In the gauze test for flooring adhesives, 1-inch wide cotton gauze was used

in place of silk cloth. Adhesive coatings are thicker than paint films and

a more open fabric seemed more likely to shorten drying time and to ’’key”

better with the adhesive. Adhesives were spread as thin as possible with

a putty knife, which was also used to coat the gauze and press it into the

adhesive.

5

No quantitative measurements were made in tests with flooring materials or with cotton gauze. Adhesion was judged mainly by the amount of adhesive

remaining on the concrete surface after the strip of material was removed,

although ease of removal was also taken into account. Flooring materials

applied to the 4-1/2- by 9-inch and 6* by 6-inch panels were cut into

1-inch wide strips at various intervals of time and the strips pulled back

manually. Sometimes it was necessary to pry up the strips with a putty

knife. The 27- by 28-inch slabs were covered with standard 9- by 9-inch

tiles, which were removed at intervals. Tests were completed and all

material removed after three months.

The gauze strips were removed beginning in 1 to 2 days, the idea of the

test being to develop a rapid method. However, results of this test

were inconsistent both as to time and as to materials, as reported

earlier. Earlier reports also mentioned that tests with flooring materials

were variable and only general conclusions could be drawn. Adhesion was

poor to concrete surfaces treated with oils and waxes, but even in such

cases, satisfactory results were achieved by using asphalt cutback

adhesive or asphalt primer.

Photographs at the end of this report show tests on the 27- by 28-inch

concrete slabs and on the corridor on the fourth floor of the Industrial

Building, National Bureau of Standards. No oozing between tiles was

noted, even with oily and waxy materials, such as Thompson’s Water Seal.

Light sanding of a slab treated with paste wax improved adhesion to

asphalt emulsion adhesive cement.

It was found that adhesion of tile cement was not always good to untreated

or steam cured panels. A good example is an untreated 27- by 28-inch

concrete slab which had been steam cured for 28 days. After curing, the

surface had a whitish appearance, suggesting efflorescence. After air

drying for several days, half of the slab was coated with asphalt cutback

adhesive cement and half with asphalt emulsion adhesive. Nine 9- by 9 -inch

vinyl asbestos tiles were laid on the slab. Some of the tiles were removed

after a month and the rest after three months. The tiles were pried up,

in each case, with moderate difficulty. About half of the concrete

surface was bare on each half of the slab. Judging from the appearance of

the concrete surface, adhesion would be considered fair to poor. However,

the concrete surface appeared ” 8 dusty8B and the underside of the adhesive

remaining on the tiles was whitish in appearance, as can be seen from the

photograph. Apparently, due to the composition of the concrete mix and

the manner of finishing, there was considerable laitance or a layer of

loose material which prevented good adhesion. Another difficulty with

6

the test method is that sometimes the bond between the adhesive and the

concrete surface is so good that when the tile is removed,, concrete is

torn from the surface and bare spots result.

The results were too variable for quantitative evaluation of curing and

parting agents or to serve as a basis for specifications. However,, from

a large number of tests,, the following tentative conclusions and recommendations are offered:

(1) Curing , parting, and other concrete treatment agents should not contain oils or waxes if resilient flooring is to be laid on the concrete

floor so treated". A specification such as CRD-C-3Q0-55 , requiring drying

time to touch in not more than 4 hours, should be sufficient to exclude

oily and waxy curing agents. It might be better to add a simple test

such as described in Method 4061 (May 15, 1 958) ^ . 5 'Drying Time (Varnishes,

Lacquers and Enamels)’*, Federal Test Method Standard No. 141. The test

is to touch the tip of a finger lightly to the coating, then touch the

finger tip immediately to a piece of clean, clear glass, observing

whether any of the coating is transferred to the clean piece of glass.

Since concrete is porous and oils and waxes may soak into the mass of

the material, this might not be suitable as a test of a coating already

applied, but as one applied to a metal panel. This could even be done

in the field, sampling the curing agent before application.

(2) Some commercial curing agents have been shown to be satisfactory as

a substrate for vinyl asbestos tile. Known formulations shown to be

satisfactory include butadiene styrene copolymer or petroleum hydrocarbon

resin dissolved in xylene or other suitable hydrocarbon solvent, sueh

that the resin content is about 25-307. and the drying time approximately

that of xylene. The product should dry to a hard film in 4 hours.

(3) Old concrete floors which have been treated with any oil or wax,

such as paraffin wax, kerosene, floor wax, etc., or the previous history

of which is unknown, can generally be tiled using asphalt cutback

adhesive cement. Such floors can also be coated with asphalt primer.

Light sanding should improve adhesion.

(4) It is unlikely that oozing between tiles is caused by curing or parting agents or by products containing oils or waxes.

(5) All parting agents that we have analyzed contain non-volatile oils

or waxes or both. Floors constructed by the lift-slab method may cause

trouble with resilient flooring installations.

7

(6) Adhesion of resilient flooring to water cured concrete depends on

the composition and finishing of the concrete. Adhesion varies considerably on the surface of a concrete slab. In performing any adhesion

tests, enough observations must be made so that the results will be

significant. In laboratory tests., It might be better to use as a standard a concrete surface treated with a known membrane curing agent.

4. PLANS FOR FUTURE WORK

It has been mentioned already that the appearance of the concrete surface

after removal of flooring material is not a perfect criterion of adhesion.

Perhaps a better property for testing adhesion is the force required to

break the bond between the concrete surface and the adhesive. Tests on

linoleum along these lines were reported in BMS 59, previously mentioned

in this report. Tests described in BMS 59 were performed with concrete

blocks and panels cast with steel pins running through them and made to

fit special yokes. These yokes were made to fit in the jaws of a Scott

tester.

The yokes described in BMS 59 were obtained for use in pull tests or as

a basis for designing new yokes. Concrete blocks and panels similar

to those used in BMS 59 were cast. The blocks were 2-inch cubes, designed

to be used in straight or 180° pull tests. A 2-inch square of flooring

material is applied to one surface of a cube and a wooden block cemented

on top of the flooring material. A steel pin is run through the wooden

block, made to fit in a yoke which fits in one of the jaws of a pull

testing machine. The concrete panels were 2- by 6- by 3/4-inch and were

designed for stripping or 90° pull tests. The yoke fits in one jaw of a testing machine and the flooring material is placed in the other jaw. It

is planned to use an Instron tester in place of the Scott tester, which

is now obsolete. The Instron tester gives more complete and precise

information.

Some concrete panels, 3- by 5- by 1 /2-inch were cast to be used in further

exploratory tests. For example, it would be desirable to test a concrete

surface for the presence of oils and waxes. One possibility would be to

press a piece off filter paper on the surface with a hot iron.

The Organic Coatings Group has been consulted with the idea of collaborating

in testing adhesion of paints to concrete surfaces.

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U. S. DEPARTMENT OF COMMERCE

Luther H. Hodges, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards at its major laboratories in Washington, D.C.,and

Boulder, Colorado, is suggested in the following listing of the divisions and sections engaged in technical work.

In general, each section carries out specialized research, development, and engineering in the field indicated by

its title. A brief description of the activities, and of the resultant publications, appears on the inside of the

front cover. WASHINGTON. D. C.

Electricity. Resistance and Reactance. Electrochemistry. Electrical Instruments. Magnetic Measurements.

Dielectrics. High Voltage. Absolute Electrical Measurements.

Metrology. Photometrv and Colorimetry. Refractometry. Photographic Research. Length. Engineering Metrology.

Mass and Volume.

Heat. Temperature Physics. Hdat Measurements. Cryogenic Physics. Equation of State. Statistical Physics.

Radiation Physics. X-ray. Radioactivity. Radiation Theory. High Energy Radiation. Radiological Equipment.

Nucleonic Instrumentation. Neutron Physics.

Analytical and Inorganic Chemistry. Pure Substances. Spectrochemistry. Solution Chemistry. Standard Refer- ence Materials. Applied Analytical Research. Crystal Chemistry.

Mechanics. Sound. Pressure and Vacuum. Fluid Mechanics. Engineering Mechanics. Rheology. Combustion

Controls.

Polymers. Macromolecules: Synthesis and Structure. Polymer Chemistry. PolymeF Physics. Polymer Characterization. Polymer Evaluation and Testing. Applied Polymer Standards and Research. Dental Research.

Metallurgy. Engineering Metallurgy. Metal Reactions. Metal Physics. Electrolysis and Metal Deposition.

Inorganic Solids. Engineering Ceramics. Glass. Solid State Chemistry. Crystal Growth. Physical Properties.

Crystallography.

Building Research. Structural Engineering. Fire Research. Mechanical Systems. Organic Building Materials.

Codes and Safety Standards. Heat Transfer. Inorganic Building Materials. Metallic Building Materials.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics. Operations Research.

Data Processing Systems. Components and Techniques. Computer Technology. Measurements Automation.

Engineering Applications. Systems Analysis.

Atomic Physics. Spectroscopy. Infrared Spectroscopy. Far Ultraviolet Physics. Solid State Physics. Electron

Physics. Atomic Physics. Plasma Spectroscopy.

Instrumentation. Engineering Electronics. Electron Devices. Electronic Instrumentation. Mechanical Instru- ments. Basic Instrumentation.

Physical Chemistry. Thermochemistry. Surface Chemistry. Organic Chemistry. Molecular Spectroscopy. Ele- mentary Processes. Mass Spectrometry. Photochemistry and Radiation Chemistry.

Office of Weights and Measures. BOLLDER, COLO.

CRYOGENIC ENGINEERING LABORATORY

Crvoge nic Processes. Cryogenic Properties of Solids. Cryogenic Technical Services. Properties of Cryogenic

Fluids.

CENTRAL RADIO PROPAGATION LABORATORY

Ionosphere Research and Propagation. Low' Frequency and Very Low Frequency Research. Ionosphere Research. Prediction Services. Sun-Earth Relationships. Field Engineering. Radio Warning Services. Vertical

Soundings Research.

Troposphere and Space Telecommunications. Data Reduction Instrumentation. Radio Noise. Tropospheric

Measurements. Tropospheric Analysis. Spectrum Utilization Research. Radio-Meteorology. Lower Atmosphere

Physics.

Radio Systems. Applied Electromagnetic Theory. High Frequency and Very High Frequency Research. Fre- quency Utilization. Modulation Research. Antenna Research. Radiodetermination.

Upper Atmosphere and Space Physics. Upper Atmosphere and Plasma Physics. High Latitude Ionosphere

Physics. Ionosphere and Exosphere Scatter. Airglow and Aurora. Ionospheric Radio Astronomy.

RADIO STANDARDS LABORATORY

Radio Standards Physics. Frequence and Time Disseminations. Radio and Microwave Materials. Atomic Fre- quency and Time-Interval Standards. Radio Plasma. Microwave Physics.

Radio Standards Engineering. High Frequency Electrical Standards. High Frequency Calibration Services. High

frequency Impedance Standards. Microwave Calibration Services. Microw'ave Circuit Standards. Low F requencv

Calibration Services.

Joint Institute for Laboratory Astrophysics- NBS Group (Univ. of Colo.).
I