Evaluation of Sulfate Resistance of Portland Cement Mortars Containing Low-Carbon Rice Husk Ash

Abstract

In this study, a low-carbon rice husk ash (RHA) was used as a supplementary cementing material in cement mortars to evaluate its sulfate resistance in sodium and magnesium sulfate solutions. The sulfate resistance of these mixtures in terms of expansion and loss of compressive strength was determined using the standard test method.. The water to cementitious material (w/cm) ratio and RHA dosage in the mortars was varied from 0.40 to 0.57 and 0 to 15% (by mass), respectively. The results from this investigation suggest that all mortars with a w/cm ratio of 0.40 showed little deterioration, indicating their high sulfate resistance. For mortars with a w/cm ratio of 0.48 and 0.57, the control mortars showed more deterioration than those with RHA. For mortars at any given w/cm ratio, the sulfate resistance decreased with an increase in the RHA dosage. Though both sodium and magnesium sulfates caused significant deterioration in the specimens, the former caused increased expansions in the test specimens while the latter caused significant loss in compressive strength. The sulfate resistance of RHA mortars was comparable with that of silica fume mortars.