Mechanical properties and hydration mechanisms of high-strength fluorogypsum-blast furnace slag-based hydraulic cementitious binder

Abstract Microstructure and mechanical properties of new binder with high fluorogypsum amount and low Portland cement amount were investigated. The strengths of mortars with fluorogypsum-blast furnace slag-based hydraulic cementitious binder (FBB) were studied at different hydration ages, showing that their later strengths increased rapidly. In 28 days, their compressive strengths, flexural strengths and softening coefficients were all above 59.0 MPa, 10.0 MPa and 0.90, respectively. Microscopic analysis indicated that their hydration products were mainly ettringite, C–S–H gels, xonotlite, dihydrate gypsum crystals, with wairakite generated after 90 days. The generation of zeolite minerals and packing action of filamentous C–S–H gels further improved the strength and water resistance of the paste.