Use of Rice Husk Ash as Partial Replacement of Cement in Sandcrete Blocks

Abstract

This paper presents the outcome of a research study aimed at the performance evaluation of rice husk ash as partial replacement of cement in sandcrete blocks used as masonry units. Rice husk from the rice cultivated in the North of Pakistan was used in the study. It was first combusted in a locally manufactured incinerator to convert it into rice husk ash (RHA) and then finely ground to powder form for use with cement. Blocks with the size of 305×203×152 mm were molded with 0, 10, 30, 40 and 50% replacement of cement with RHA to find compressive strength at 3, 7, 14 and 28 days age of curing. The results showed that water requirement for the required workability of the sandcrete increased along with the RHA content, whereas the compressive strength decreased with increase in RHA content. However, the comparison of compressive strengths of RHA sandcrete blocks with the strength of commercial concrete blocks available in the market and used as masonry units in Pakistan showed that sandcrete blocks having the sand to binder ratio of 1:8 and using up to 40% of RHA as replacement of cement gave larger compres-sive strength than that of commercial concrete blocks and only marginally lower strength for 50% replacement.