Effect of Curing Temperature on the Hydration of Calcium Sulfoaluminate Cement-Ground Granulated Blast Furnace Slag-Gypsum Mixture

Abstract

In this work, the effect of curing temperature on the hydration of calcium sulphoaluminate cement (CSAC) blended with ground granulated blast furnace slag (GGBFS) and flue gas desulfurization gypsum (FGDG) was investigated. The hydration products (mineral phase, micromorphology, and amount), pore structure, setting time, and mechanical strengths of cement pastes or mortars cured at 5, 10, 20, and 35°C for different times were monitored by X-ray diffractometer (XRD), thermogravimetric-differential scanning calorimetry (TG-DSC), scanning electron microscope (SEM), mercury intrusion porosimetry (MIP), Vicat apparatus, and pressure testing machine. Results showed that high curing temperature accelerated the early-age hydration of the blended cement paste; however, it had little effect on the 28-day hydration. Meanwhile, high curing temperature increased the total porosity of hardened cement paste. The setting time of cement paste had an obvious decrease with increasing curing temperature. The 1-day and 3-day mechanical strengths of mortars increased as the curing temperature increased from 5°C to 35°C, while the 28-day mechanical strengths reduced gradually.