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iipril 14 , 1956

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HJTEGRiiL UaTLRPHOOFING FOR CONGLFTE

This is a digest of that portion of Bureau of Standards Lesearch

Paper iiP394 (December 1931) , ’’Tests of Integral and Surface Waterproofing for Goncrete",-^ by G. H, Juiiiper, dealing with integral waterproofing.

Purpose of tests: To determine the permeability, absorption and

corapressive strength of concrete treated v/ith integral waterproofing

compounds.

Materials used: Fifty coDmiercial treatments were classified in

accordance v/ith their, chemical compositions and grouped as follows:

(1) Calcium Ghloride

(2) -Galcium Ghloride plus lliscellaneous Materials

(3) Soaps

• (4) Hydrated Lime plus Soap

(5) Finely Subdivided Materials used as Fillers

(6) Miscellaneous Materials

These' were incorporated into a 1:3:6 concrete, applied as directed

and in amounts specified by the manufacturers. The specimens so treated

were subjected to a water pressure of 20 pounds per square inch for one year, and their perraeability compared with untreated concrete of the

same quality (established as standard) and tested in a similar manner,

Gompression and- absorption tests \/ere also made.

Lean concrete was purposely adopted for use to simulate that segregated portion of concrete through which leaks generally occur. Since it

^Obtainable from Superintendent of Documents, Governiaent ibrinting

Office, Washington, D. G. (Price 10 cents)

- 1 - 042036-M
is not difficult to muice concrete that is irapenaeable to v^^ater under

pressure of fO pounds per square inch, this being in exaess of pressures generally encountered, the use of adr.iixtures seeias needless.

However, even iii placing e;.cellent concrete, partial segregation into

its constituents raay develop at certain places, allowing the passage

of water. Consequently, waterproofing becories a- niatter for consideration. Of the adiiiixtures used, -sorae reduced the permeability of the

concrete while others seemed -to be of no value. Ho doubt, some of the

integral agents produce unctuousness and allow ease of placing, which

tend to prevent segregation and may react with cement to reduce the

voids .

Stearates and calcium chloride treatments were as effective as any used and are readily . obtainable, on. the open market without paying

fanciful prices

.

In the summary here 'given ' statements are somevhiat general. and. , apply more particularly to the' results obtained for the materials as, a 'group.

(1) Calciura Chloride group: The addition of calcium chloride.

did not materially reduce' permeability or absorption. It. did,, how-:. :• ever, seem to increase the compressive strength. Further amounts .of . calciim.i chloride per bag of cement decreased the initial permeability.

(2) Calcium Chloride plus Miscellaneous Materials group; The

incorporation of such materials as soap, silica, and aluminum chloride

with calciura chloride did not materially reduce the permeability nor absorption. Comipressive strength was only slightly affected. Additions of soap to calciuir chloride caused a reduction in absorption but

¥i/ithout the usual increase in strength asw^ith Calciura chloride alone,

(3) Soaps group: The addition of soap alone caused increases

in permeability. The strength of concrete containing oleate soap v/as

appreciably reduced. Other soaps reduced the strength only slightly.

In general, the presence of soap caused a reduction in absorption,

and a higher peimeability than the other Waterproofings which were , used.

(4) Hydrated Limes and Soaps group: Hydrated . limes mixed with .. soaps gave a higher permeability than the standard, hov/evcr, not so high as when soaps alone v/ere added as in group (3).. The compressive

strength o'f this group was generally decidedly less than standard.
(5) Finely Subdivided Ii^terials used as Fillers group: The

finely subdivided compounds used as fillers generally reduced the

permeability and increased the compressive strength of the specimens

The absorption v/as about the same or greater than standard.

(6) Liiscellaneous Materials group: The permeability of con- crete was not reduced by the addition of such miscellaneous materials

as cellulose and wax, or by the addition of materials containing un- combined fatty acids, fluosilicate , naphalene, vaseline, butyl stearate,

or coal tar. These compo'onds in general lowered the compressive

strength but reduced absorption. Ihe presence of a mixture of hea^^y

mineral oil and a saponifiable oil reduced the permeability, absorption, and also the strength.

Uxility of \vaterproof ings

If any benefit is to be derived from the use of waterproofings

,

the type used should be selected according to the exposure of the con- crete .

In order that concrete resist Virater under pressure, the only com- pounds to be considered are calcium chloride or the group of finely

divided materials.

adding approximately 2 percent (by weight of cement) of commercial

calciimi chloride to the concrete should hasten the hardening and tend

to reduce the permeability, especially if the period of damp curing is

short. The addition of finely divided materials to concrete mixtures

which are deficient in fine particles, should reduce permeability under

pressure. The amount to be added depends on the quantity of fine

particles present in the mix.

The addition of integral waterproofings of the v;ater repellent

tjqje such as the soaps and fatty acids (stearates) should be: used only

for reduction of capillarity. The amount to be added to the concrete

mix should provide a fatty acid content equal to from 0.1 to 0.2 percent

of the weight of the cement.