Pozzolana Cement Obtained By Calcining Raw Clays/Rice Husks Mixtures

The aim of the study was to investigate thermal activation of clays from selected regions of Mwea using rice husks (RH), as the only source of energy, to produce low cost pozzolanalime cement. The clays were sampled from Gikiiro and Ugweri regions and coded 2060 and 2062 respectively. The clays were calcined at temperatures between 500 and 800 oC for one and two hours. Further, the raw clays were blended with rice husks at different ratios and fired in a fixed bed kiln (FBK). The resultant ashes were subjected to the usual pozzolanicity tests. The ashes were also mixed with lime at different ratios and subjected to compressive strength tests. There was no significant difference in the test results between calcined clays at different activation periods and temperatures. Except for the Ugweri clay at 2:1 ratio, there was no significant difference between the 1:2, 1:1 and 2:1 RH to clays ratios in terms of compressive strength development. The results suggest that the clays, whether calcined separately in an electric furnace, or in mix with RH, are pozzolanic materials. Further, the clays were activated using rice husks, without any other external source of energy, to produce pozzolanic ash