Influence of Calcium Sulfate Varieties on Properties of Calcium Aluminate Cement-Based Self-Leveling Mortars

摘要

The effect of calcium sulfates varieties on the properties of calcium aluminate cement-based self-leveling mortar have been investigated, and the hydration kinetics, hydrated products and microstructures were measured by isothermal calorimeter, X-ray diffraction and mercury intrusion porosimetry, respectively. The results show that the technological properties of mortars are significantly affected by calcium sulfate varieties and content. The setting times were shortened drastically with the addition of calcium sulfates. Mortars with hemihydrate showed higher early strength and less drying shrinkage. In contrast, using anhydrite in mortars caused lower strength and higher drying shrinkage at early age but larger growth of strength in the late. The increasing calcium sulfates content might result in the delay of main hydration peak in the heat evolution curve. Moreover, mortar microstructures were optimized by addition of β-hemihydrate, the proportion of large pores were lower than that of mortars with anhydrite.