Hydration and marine durability of high-ferrite Portland cement-fly ash blends under varied curing temperature

Abstract

To meet the demanding conditions of marine environment, cementitious materials of concrete must exhibit low hydration heat, high strength, and superior erosion resistance. This study investigates the hydration and marine durability of high-ferrite Portland cement (HFPC)-fly ash blends under varied curing temperature. Its mineral composition, rich in C4AF and C2S, results in significantly slower and lower early-age heat release – only 86.7% of ordinary Portland cement at 3 days (20°C). Fly ash slightly delays early hydration and reduces heat release of HFPC, but accelerates it after an initial inhibition period (~12 h at 20 °C, ~6 h at 60 °C) through providing hydration product nucleation sites and dilution effects. Incorporating fly ash (40% being optimal) markedly refines pore structure and enhances chloride penetration resistance. HFPC-fly ash blends demonstrate excellent early durability in NaCl and Na2SO4 solutions, offering promising marine applications.