The effectiveness of powdered emulsions (powdered cement modifiers) and aqueous polymer dispersions (aqueous cement modifiers) on improvements in strength and elastic properties of mortars is investigated in this paper. Polymer-modified mortars using various powdered and aqueous cement modifiers were prepared with variation in polymer-cement ratio, and tested for flexural strength, compressive strength, tensile strength, deflection, extreme tensile fiber strain and tensile strain. It is concluded from the test results that powdered cement modifiers affect the properties of mortars similarly as the aqueous cement modifiers and the powdered polymer-modified mortars can be used in the same manner as the aqueous polymer-modified mortars for practical applications. 1200 M.U.IC Afridi et al. Vol. 24, No. 7 Materials Cement and Fine Aggregate
Ordinary portland cement and Toyoura standard sand as specified in JIS (Japanese Industrial Standard) were used in all mixes.
Cement Modifiers
Commercially available, four powdered and two aqueous cement modifiers were used. The powdered cement modifiers used included one brand of poly (vinyl acetate-vinyl carboxylate) (VA/VeoVa) type and three brands of poly (ethylene-vinyl acetate), (EVA) type. The aqueous cement modifiers used were one brand of EVA emulsion and one brand of styrene-butadiene rubber (SBR) latex type. Their typical properties are given in Table 1. Before mixing, a silicone emulsion type antifoamer containing 30% silicone solids was added to the cement modifiers in a ratio of 0.7% of the silicone solids in the antifoamer to the total solids in the powdered and aqueous cement modifiers.