Performance enhancement mechanism of limestone calcined clay cement (LC3) blended with seawater

This study investigates the hydration mechanism and microstructural evolution of limestone calcined clay cement (LC 3 ) prepared with seawater. Results demonstrate that seawater significantly enhances compressive strength across all curing ages. At 28 days, seawater-based mixtures containing 35% and 50% LC 3 exhibited strength increases of 32% and 17%, respectively, compared to deionized-water references. Mechanistic analyses reveal that seawater effectively activates the pozzolanic reaction and accelerates calcium hydroxide consumption, promoting additional C-A-S-H gel formation. Notably, in the 35% LC 3 paste, seawater increased the calcium carbonate reaction degree by 115%. The resulting carboaluminate phases further react with chloride ions to form Friedel's salt, which fills pores and contributes to strength development. Furthermore, the synergistic effect of LC 3 and seawater refines the pore structure by reducing the critical pore entry radius. This microstructural densification endows the binder with excellent resistance to gas and water transport, highlighting the potential for seawater-mixed LC 3 in sustainable constructiont.