Experimental and RSM-based multi-objective optimization of low-carbon high-performance concrete incorporating silica fume and slag: Compressive strength, durability, environmental impact, and cost analysis

This study employs response surface methodology (RSM) to comprehensively evaluate the effects of silica fume and ground granulated blast-furnace slag (GGBFS) on the mechanical, durability, environmental, and economic performance of concrete. The novelty of this research lies in the integrated assessment of these parameters within a multi-objective optimization framework across a broad range of mix design variables. Key properties, including compressive strength, corrosion resistance, time to corrosion initiation, and carbonation depth, were analyzed alongside indicators of CO 2 emissions, energy consumption, and production cost. Results revealed that the optimal combination of silica fume (approximately 9–12%) and slag (30–40%) enhanced compressive strength by more than 30%, improved corrosion resistance by over 50%, doubled the time to corrosion initiation, and reduced carbonation depth by up to 40%, while simultaneously lowering the environmental index by more than 60% compared to ordinary Portland cement reference mixtures. Furthermore, five optimization scenarios—durability-focused, cost-driven, eco-efficient, high-strength with controlled durability, and Pareto frontier—were examined, offering flexibility for selecting mix designs tailored to different project priorities. The findings highlight that the systematic and combined use of supplementary cementitious materials within an RSM framework provides a practical pathway for developing low-carbon, durable, and economically viable concretes.