Studying the effect of waterproofing admixtures on some properties of cement mortar

Abstract

This study mainly focused on testing the feasibility of using some finely divided materials (waterproofing) as a permeability-reducing admixture in mortar after mixing with sulphate resisting cement and fine sand and evaluating the effects of these materials on the other properties of mortar. Bentonite and limestone dust are used as a permeability –reducing admixture. Permeability, compressive strength, modulus of rupture, density and ultrasonic pulse velocity tests have been investigated in this study. At 1% of bentonite addition, the quantity of penetrated water reaches about 91% of the water permeation quantity of the control mix. The results indicate that the optimum percentage of limestone is 2.5% of the cement weight, the quantity of penetrated water through mortar at this level is about 18.2% and 47.8% of the water permeation quantity of the control mix of rich and lean mixes, respectively. The addition of 7.5% of limestone dust in rich mix results in an improvement in compressive strength by about 51.8%. Other mortar properties including modulus of rupture indicates trends similar to that observed in compressive strength for all materials used in this study.