Rice Husk Ash and its Application as a Cement Replacement Material in Kenya

Abstract

AAS and XRD amdysls of rice husk ash (RHA) from Mwea and Ahero regions in Kenya, and physical tests of the strength of cernenl;itious materials obtained when the ash is used to replace ordinary portland cement (OPe) are reported. The major constitnent of the RHA was sHica (82.3-89.9%) which was mainly amorphous. Both regions had minor yariations in the amount of Si, K, Fe, AJ,MD, Mg, aad Ca, but sigJUlic:ant differences in the levels of Na and P were found. Heating RHA to lOOO"C was found to induce crystallinity in the silica. An indirect method of determining the amount of silica in RHA by use of the loss on ignition (I.O.I) is suggested. Results show that a stroager cementitious material Is obtained by replacing upto 13.4% OPC with RHA.