LCA-guided design and optimisation of sulfoaluminate cement with GGBFS and fly ash

The urgent need to mitigate the carbon dioxide footprint of cement production has driven the development of innovative blended cements. The focus of this study was a hybrid system integrating sulfoaluminate cement (SAC), ground granulated blast-furnace slag (GGBFS) and fly ash (FA), with desulfurisation gypsum (DG) as a functional addition to balance performance and sustainability. Life cycle assessment revealed that the optimised blended cement formulation achieved a 70% reduction in carbon dioxide emissions compared with conventional ordinary Portland cement, primarily attributed to 50% SAC replacement and reduced clinker dependency. The experimental results demonstrated that 4% DG incorporation enhanced the 28-day compressive strength and reduced the chloride diffusion coefficient, correlated with a refined pore structure and suppressed harmful phase transitions. Microstructural analysis confirmed that the DG modulated the hydration kinetics, which promoted continuous ettringite formation and reduced the pores of size >50 nm by 17.7% at 28 days, thereby enhancing matrix densification. The synergy within the GGBFS–FA binary system under DG modulation established a viable pathway for sustainable cement design, addressing the goals of both reducing carbon dioxide emissions of construction materials and industrial waste valorisation.