Mechanical properties and durability assessment of rice husk ash concrete

The effect of rice husk ash (RHA) on concrete properties and durability was studied. To establish the suitable proportion of RHA for the partial replacement of cement, concrete mixtures with 0–30% RHA were produced and their mechanical properties were determined. The effect of RHA on the uniformity of concrete was also examined. The durability of the specimens exposed to aggressive environments (5% NaCl with wet-dry cycling) was evaluated for a total of eleven months. The degree of damage was studied by determining the percentage of reduction in compressive strength and chloride ions penetration as compared with control specimens that had cured normally. The results indicate that the partial replacement of cement by RHA improved durability and homogeneity but did not increase the early age compressive strength of concrete. However, concrete containing RHA showed higher compressive strength at the later ages. The scanning electron microscopy (SEM) studies of the microstructure of mortar specimens showed that the RHA filled up the pores and this explained the superior mechanical performance of the mortar with RHA.