Effect of the fineness of limestone powder on the properties of calcium sulfoaluminate cement

The effects of ordinary limestone powder (OLP) and ultrafine limestone powder (UFLP) on the fluidity, setting time, compressive strength, hydration heat and microstructure of calcium sulfoaluminate cement (CSA) were investigated. The results show that finer limestone powder reduces the fluidity and setting time of CSA. Increasing fineness of limestone powder improves the growth rates of strength and chemical bound water content, and higher compressive strength and chemical bound water content are obtained. The hydration of CSA is dramatically promoted by adding UFLP, and the promoting effect increases with increasing dosage, but cumulative hydration heat is reduced. The higher content and finer limestone powder result in larger amount of hemicarbonate and minor amount of monosulfate phase (AFm). The microstructure of hardened CSA paste is densified by adding UFLP. Owing to the poor bond between limestone powder and surrounding hydrates, the compressive strength of CSA mortar containing larger amount of limestone powder is low.