Low-Temperature Calcination of Belite-Calcium Sulphoaluminate Cement Clinker and the Hydration Process

To reduce the calcination temperature of belite (beta-C2S)-calcium sulphoaluminate (C(4)A(3)$) cement clinker, hydrothermal curing was applied to mixed raw materials before calcination. The influences of calcination temperature on the mineralogical composition of cement clinker were investigated, and the optimum beta-C2S/C(4)A(3)$ ratio was deduced. The phase and microstructure evolution of the hydrated paste were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The compressive strength development was also tested. The results showed that after hydrothermal curing at 95 degrees C, the belite-calcium sulphoaluminate cement clinker can be prepared with a low-temperature calcination of 1,200 degrees C. When the beta-C2S/C(4)A(3)$ ratio reached 50%/50%, the cement pastes had the highest 3- and 28-day compressive strengths of 37.34 and 62.94 MPa, respectively. The main hydration product formed in the cement paste was ettringite. (C) 2021 American Society of Civil Engineers.

Automated summary

Hydrothermal curing before calcination can reduce the temperature required for belite-calcium sulphoaluminate cement clinker production, leading to high compressive strength in cement paste with optimal beta-C2S/C(4)A(3) ratio. The main hydration product observed was ettringite in the hydrated paste.