Abstract
Effects of cement composition and silica content on the microstructure and compressive strength of autoclaved mortar with silica powder were studied. The strength of autoclaved mortars prepared by mixing with portland cement and silica powder with low water cement ratio (W/S=0.25) was affected by the amount of silica powder. The maximum strength was obtained for the mortar with silica content where calcium hydroxide was completely consumed by the reaction with silica powder added. The correlation between formation of tobermorite and compressive strength of autocraved mortar was not clear. The excessive addition of silica powder resulted in the formation of gap between the silica particles and matrix, with decreasing in the strength of mortars. A correlation between pore volume and compressive strength was obtained when these gap did not exist.
