Techno-ecological Optimization of Silico-Manganese Fume and Blast Furnace Slag Blended Cement Mortar Using Response Surface Methodology

This study investigates the optimization and modeling of greener cement mortar incorporating ground granulated blast furnace slag (GGBFS) (0–50%) and silico-manganese fume (SiMnF) (0–20%) to identify optimal combinations that balance workability, strength, and sustainability. Additional mix parameters included sand-to-binder and water-to-cementitious material ratios ranging from 1.5 to 2.5 and 0.35 to 0.45, respectively. A total of 25 mortar mixes were designed using response surface methodology (RSM) and evaluated for flowability and compressive strength up to 56 days of ambient curing. The optimization was essential to address the complex interactions among investigated parameters, particularly in blended systems involving low-OPC content and reactive industrial by-products. Statistical modeling of flow and 28-day strength yielded highly accurate predictions (R² > 0.95) and facilitated optimization of mix parameters. Five optimization scenarios were proposed wherein the sustainable binary and ternary mixes demonstrated the feasibility of achieving flow values in the range of 140–178 mm and strength values in the range of 43–51 MPa, corresponding to 90% and 85%, respectively, of the control mix. Microstructural analysis revealed that the combined use of SiMnF and GGBFS influences hydration kinetics, refines the matrix structure, and improves pore connectivity through the modification of Ca/Si ratios. Finally, this study underscores the trade-off between mechanical performance and environmental benefits, guiding the selection of mix designs for specific applications. Beyond the technical merits, this study advances the valorization of industrial by-products, conserves natural resources, mitigates water scarcity, and supports carbon neutrality, aligning with the Sustainable Development Goals (SDGs) in the construction sector.