— This paper clarifies phenomena occurring during the production of gypsum binder, anhydrite, and potentially eco-friendly calcium sulfate-based ceramics at 22–1300 °C by in-situ XRD, thermal analysis, and SEM.

 — The results show that the obtained hemihydrate gypsum mixing with water can prepare high-performance building gypsum after the FGD gypsum adding 3–5 wt% of CaO is calcined at 160–220 °C...

Depending on the calcination by-product(s), the behavior of set gypsum (after re-hydration) can fluctuate. For example, it has been observed that set α-hemihydrate can obtain a four times higher compression strength than concrete (Arredondo 1961; Ye 2011).

Calcium sulphate dihydrate (CaSO4·2H2O or gypsum) is used widely as building material because of its excellent fire resistance, aesthetics, and low price. Hemihydrate occurs in two formations of α- and β-type.

 — The effect of PG calcination temperature (100 °C, 140 °C, 180 °C, and 220 °C) on the properties of SG was evaluated, and it was found that 180 ºC calcination temperature was able to fully convert the PG to β-hemihydrate SG.

 — Gypsum calcined at 400 °C (Fig. 4 c) contained ∼ 90 wt% anhydrite and exhibited a feather-like morphology likely due to further mineral contraction, which can be explained by the additional reduction in molar volume of ∼ 15 % upon formation of anhydrite II (45.64 cm 3 /mol molar volume).

 — Calcination at different temperatures, three phase CG structures, namely, bassanite, anhydrite III, and anhydrite II, may be generated. We herein investigated the relationship between the phase structure and the efficacy of CG and the optimum phase structure for CG.

 — In the US, 47% of the domestically mined and synthesised gypsum supplies are calcined to hemihydrate to be used as plaster 14.

 — The aim of the study was to evaluate the effect of the calcination temperature of synthetic gypsum binder on the binding properties of innovative gypsum pastes, as well as on the properties of masonry and plastering mortars.

 — The dehydration of PG to β-hemihydrate gypsum depends on the calcination temperature and time, and an increase in the calcination temperature is beneficial to shortening the dehydration time.