•FGD gypsum is firstly applied for the production of calcium sulfoaluminate cement.•Hydration of FGD gypsum blended CSA cement at 0, 10, 20 and 40 °C were identified.•The utilization of FGD gypsum in producing CSA cement is very promising.With the rapid development of industries, flue gas desulfurization (FGD) gypsum has become one of the bulk industrial solid wastes which trigger many local environmental problems in China. Due to the high purity of calcium sulfate dehydrate, FGD gypsum has a high potential for eco-friendly calcium sulfoaluminate (CSA) cement manufacture. This would reduce nature resource and energy consumption in cement industry, and bring economic and ecological benefits for waste management. Given the high sensitivity of hydrates to the temperature, the hydration features of FGD gypsum blended CSA cement under usual climate temperature (0, 10, 20 and 40 °C) were identified by using calorimetry, XRD and DSC-TGA analysis in this work. Meanwhile, the compressive strengths and dimensional stability of prepared pastes were measured in an effort to correlate the overall performance with microstructure development. Results demonstrate that the hydration of CSA cement is highly dependent on the variations of FGD gypsum dosage and curing temperature. The addition of FGD gypsum contributes to more ettringite and alumina hydroxide generated under all curing regimes, and restrains the formation of monosulfate and strätlingite at 40 °C. Therefore, it favors the strengths development of those pastes cured at 40 °C. Additionally, moderate dosage of FGD gypsum leads to the lowest shrinkage. As a by-product generated from industry, utilizing the FGD gypsum in CSA cement production is a promising and value-added way for waste management, especially when the products applied under high temperature climate region.

In this paper, the effects of curing temperature on the hydration of calcium aluminate cement (CAC) dominated ternary binders (studied CAC: Portland cement: calcium sulfate mass ratio were 22.5: 51.7: 25.8) were estimated at 0, 10, 20 and 40 °C, respectively. Both α-hemihydrate and natural anhydrite were employed as the main source of sulfate. The impacts of temperature on the phase assemblages, morphology and pore structure of pastes hydrated up to 3 days were determined by using X-ray diffraction (XRD), backscattered electron imaging (BEI) and mercury intrusion porosimetry (MIP). Results reveal that the main hydration products are firmly related to calcium sulphoaluminate based phases. Increasing temperature would result in a faster conversion from ettringite to plate-like monosulfate for both calcium sulfate doped systems. When the temperature increases to 40 °C, an extraordinary formation of strätlingite (C2ASH8) and aluminium hydroxide is observed in anhydrite doped pastes. Additionally, increased temperature exerts different effects on the pore structure, i.e. the critical pore diameter shifts to finer one for pastes prepared with α-hemihydrate, but changes to coarser one for those made with anhydrite. From the mechanical point of view, increased temperature accelerates the 1-day strength development prominently, while exerts marginal influence on the development of 3-day strength.