chapter  4
16 Pages

- Rice Husk Ash

Rice husk ash (RHA), used as a pozzolanic admixture in cement and concrete, is obtained from the combustion of rice husk (RH) under certain conditions of the surrounding environment, temperature and residence time* in a combustor, and subsequent size reduction. It contains low unburned carbon, and silica is mostly in amorphous form. RHA manufactured in the modern ¤uidized or cyclonic bed reactors has high surface area of the order of 20-40 m2/g, comparable with that of silica fume (SF). It is a material with proven pozzolanic characteristics and is added to cement and concrete as a partial replacement of Portland cement. However, its application has not been widely commercialized as yet, mainly on account of the nonavailability of RHA of the desired pozzolanic characteristics on a large scale on the one hand and the lack of awareness about the potential for RHA as a mineral admixture on the other.