Ceramics-Silikáty 70, (1) 138 - 150 (2026)

Supersulfated cement (SSC) is considered a promising low-carbon cement, but its low early strength largely limits its application. Compared with dihydrate gypsum, anhydrite shows a much higher dissolution rate, which could promote the formation of ettringite (AFt) and improve the early strength of SSC. In this study, fluorogypsum (FG), primarily composed of anhydrite, was used to prepare SSC. The influence of the FG fineness on the hydration and properties was investigated. The results show that increasing the FG fineness increases the water demand at normal consistency. However, the early-age dissolution rates of Ca²⁺, Al³⁺, and SO₄^2- in SSC can be accelerated by an elevated FG fineness, thereby increasing the AFt saturation index (SI) and promoting AFt precipitation as the main hydration product of SSC. Therefore, increasing the FG fineness improves the 3-day compressive strength of SSC. At the hydration age of 28 days, with increased fineness, the amount of AFt also increases, while the amounts of mesopores and large pores decrease. Therefore, increasing the FG fineness improves the 28-day compressive strength of SSC. In addition, increasing the FG fineness could significantly reduce the drying shrinkage. This study provides practical guidelines for optimising the FG use in SSC and improving the early strength, thereby promoting its practical application.