Ceramics-Silikáty

The utilization of fluorogypsum (FG) is limited by its low early strength and poor dimensional stability. In this study, FG was activated using low dosages (0.25-1.0 wt%) of Na₂SO₄, K₂SO₄, and KAl(SO₄)₂·12H₂O in the presence of 1 wt% quicklime, while 5 wt% desulfurization gypsum (DG) was introduced as seed crystals to promote heterogeneous nucleation. The effects on hydration kinetics, mechanical properties, and dimensional stability were systematically investigated. The results demonstrate that the combined action of low-dosage sulfate activation and DG seeding significantly enhances early hydration, and that mixtures with higher early hydration exhibit improved strength and reduced expansion. The optimal activator dosage was identified at approximately 0.5 wt% for all systems, providing a balance between hydration kinetics, strength development, and dimensional stability. Compared with continuous standard curing (CSC), staged curing (STC) of “3 days of standard curing–7 days of air drying–re-curing” significantly enhanced strength development due to microstructural densification and secondary hydration. These results indicate that the combined regulation of sulfate activation, crystal seeding, and curing regime enables effective control of early hydration, long-term performance, and dimensional stability in FG-based systems, which is essential for improving FG-based materials