Effect of Rice Husk Ash Silica as Cement Replacement for Making Construction Mortar

Abstract

Rice husk ash (RHA) is used as a replacement to cement to produce mortar. The effect of 5, 10, and 15wt% addition to the density and compressive strength of mortar is investigated. It was found that with the increasing addition of RHA causes the decrease of compressive strength and density of mortars. Compressive strength of mortar drops with addition of RHA, from a value of 42 MPa of no RHA addition, to 24 MPa of 15wt% RHA addition. Reduction in compression strength may be due to the decrease in density, which arises from porous RHA. This is more dominant in mortar made from addition of RHA without prior acid treated. Carbon residue and impurity in RHA further reduce the compressive strength of mortar. In addition, this research validate the use of a more environmentally friendly citric acid for partially removal of oxide impurities prior to burning the rice husk.