Studies on effects of burning conditions and rice husk ash (RHA) blending amount on the mechanical behavior of cement

The properties of RHA samples obtained at different conditions in muffle furnace and their effects on the mechanical behavior of cement have been studied. The properties were characterized by SEM, XRF, XRD and specific surface area. The effect of using RHA as a partial replacement for cement has been investigated by compressive and flexural strengths test. It is showed that in muffle furnace 600 °C is the appropriate temperature for RHA preparation with large specific surface area due to the existences of nanoscale and amorphous SiO₂. While, long combustion time could increase pozzolanic activity of RHA. The presence of K could decrease the specific surface area and increase the residual carbon content which content should be control strictly. RHA obtained in proper conditions can be used as cement additive to increase compressive and flexural strengths of cement mortar specimens. It is verified that RHA replacement ratio of 10% (by weight) has the best enhancement effect on cement strength.