Influences of the dosage of dolomite powder on the fracture properties and volume stability of cement-based materials

Abstract

The effects of dolomite powder dosage on the fracture properties and volume stability of cement-based materials were investigated by three-point bending method and corrugated tube method, respectively. The experiment results showed that the fracture toughness of cement mortar incorporating dolomite powder was raised compared to that of reference cement mortar. After dolomite powder was added into cement paste, the improvement of fracture toughness, flexure, and compressive strength was observed due to the formation of a new phase (magnesium hydroxide and calcium carbonate) combined with the nucleation and physical filling effect. Autogenous shrinkage of samples incorporating dolomite powder were higher than that of the control samples because the addition of dolomite powder increased the surface tension of water in pores and the compression on the walls of capillary pores, facilitating higher autogenous shrinkage. Drying shrinkage of cement pastes blended with dolomite powder was lower than that of the control samples. The refinement of the pore structure of samples incorporating dolomite powder decreased the internal capillary pressure, causing smaller drying shrinkage.