Influence of sillimanite sand and corundum sand on the mechanical property, durability and pore structure of cement mortar

Abstract

The present study investigates the effects of sillimanite sand and corundum sand on the mechanical property, durability, and pore structure of cement mortar. Normal sand in the cement mortar mix was replaced with sillimanite sand or corundum sand at 25, 50, 75, and 100 % by volume. Further, a binary blend of sillimanite sand and corundum sand was considered to study the dual aggregate effect on cement mortar. The incorporation of 75 % corundum sand in the mortar improved the compressive strength and flexural strength by 177.7 % and 41.5 %, respectively. The higher hardness, specific gravity, and rough surface texture of corundum sand improved the mechanical properties. Further, corundum sand was found to increase the bulk density and reduce the number of permeable pores as well as the sorptivity, shrinkage, and pore connectivity in the mortar. The properties of mortar prepared using sillimanite sand and binary blend (sillimanite sand and corundum sand) were superior to those of the control sample. The average particle size of sillimanite sand was 2.40 times lower than that of normal sand. The lower particle size of the sillimanite sand formed a dense microstructure, which enhanced both the strength and the durability. It is concluded that sillimanite sand and corundum sand are feasible alternatives to normal sand in the design of engineered cement mortars.