Mechanical Properties and Chloride Penetration Resistance of Low-Carbon Concrete with Blended Binder Systems

The production of ordinary Portland cement (OPC) is associated with substantial CO 2 emissions, while reinforced concrete structures exposed to marine or deicing-salt environments require improved resistance to chloride-induced deterioration. Although supplementary cementitious materials (SCMs) and fine mineral powder (FMP) have been used to reduce cement consumption, further clarification is needed regarding how binder composition and curing condition jointly influence strength development, shrinkage, carbonation, chloride binding, and chloride transport. This study investigated the mechanical properties and chloride penetration resistance of low-carbon concrete with blended binder systems incorporating ground granulated blast-furnace slag (GGBS), fly ash (FA), silica fume (SF), and FMP. Concrete mixtures with design compressive strength levels of 30 and 45 MPa were prepared using OPC, GGBS, and FA binder systems with FMP substitution, and an 80 MPa ternary binder mixture containing FA and SF was also examined. The experimental program included compressive strength, flexural strength, splitting tensile strength, static modulus of elasticity, drying shrinkage, accelerated carbonation, salt-water immersion, water-soluble chloride, total chloride, chloride binding ratio, and apparent chloride diffusion coefficient evaluations. The results showed that FMP substitution increased compressive strength, reduced carbonation rate coefficients, increased chloride binding ratio, and decreased the apparent diffusion coefficient, particularly in blended binder systems. These findings indicate that optimized blended binder systems can contribute to low-carbon concrete with enhanced durability in chloride-bearing environments, provided that mechanical performance, dimensional stability, carbonation resistance, and chloride binding capacity are considered together.