Evaluation of Sustainable Concrete Incorporating Industrial By-Products

Abstract This research investigates the synergistic mechanical, microstructural, and durability performance of sustainable concrete incorporating Ultra-Fine Ground Granulated Blast Furnace Slag (UFGGBS), conventional Ground Granulated Blast Furnace Slag (GGBS), and copper slag as a partial replacement for natural fine aggregates. With global cement manufacturing accounting for roughly 7 − 8% of anthropogenic carbon dioxide (CO2) emissions and natural river sand depletion reaching critical ecological thresholds, partial material substitution offers a vital, scientifically backed pathway toward green infrastructure development. In this experimental study, Ordinary Portland Cement (OPC 53 grade) was partially replaced by a constant 30% mass fraction of conventional GGBS alongside varying high-performance levels of UFGGBS (10%, 20%, 25%, and 30%). Concurrently, natural river fine aggregate was substituted at a constant rate of 50% with industrial byproduct copper slag. Comprehensive testing was conducted across fresh properties, destructive mechanical evaluations, non-destructive wave propagation, long-term durability metrics, and morphological analysis via Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS). The findings demonstrate that optimal replacement dosages significantly refine pore size distribution, enhance particle packing density, accelerate early and late-stage compressive strength, and drastically lower permeability indices against aggressive chloride, carbonation, and acidic environments, establishing a robust framework for high-strength sustainable construction. Furthermore, the thermodynamic stability of the hydration products formed through accelerated pozzolanic interactions ensures long-term volumetric stability and mitigates micro-cracking under sustained thermomechanical stress. Beyond immediate strength gains, the multi-scale integration of supplementary cementitious materials alters the pore morphology from continuous percolation pathways to isolated capillary pockets, fundamentally restricting aggressive ionic ingress and extending the operational design life of reinforced concrete structures in aggressive marine and industrial environments. Keywords: Sustainable Concrete, Ultra-Fine GGBS, Copper Slag, Compressive Strength, Durability, Microstructure, Green Infrastructure, Interfacial Transition Zone, Pozzolanic Reactivity.