Sustainable Utilization Of Copper Slag, Iron Slag And Recycled Concrete Aggregate For High-Performance And Durable Concrete

Abstract

The increasing demand for infrastructure has intensified the consumption of natural aggregates and the disposal burden of industrial and construction wastes. This study investigates the combined use of copper slag (CS), iron slag (IS), and recycled concrete aggregate (RCA) as sustainable replacements for conventional aggregates in M30 concrete. Twenty-eight concrete mixes, including a control mix, were prepared by varying CS and IS at 30%, 40%, and 50% as fine aggregate replacements and RCA at 20%, 25%, and 30% as coarse aggregate replacement. Mechanical performance was evaluated using compressive, flexural, and split tensile strength tests at 28 days, while durability was assessed through rapid chloride permeability test (RCPT), half-cell potential measurement, and accelerated corrosion/gravimetric weight loss evaluation. The optimum mix, M14, containing 40% CS, 40% IS, and 25% RCA, achieved compressive, flexural, and split tensile strengths of 34.0 N/mm², 6.9 N/mm², and 3.80 N/mm², respectively. Compared with the control concrete, these values represent improvements of 17.24%, 25.45%, and 9.51%, respectively. M14 also recorded the lowest reported RCPT charge passed of 392.36 C and the lowest corrosion rate of 5.38 mpy, confirming improved resistance to chloride ingress and steel reinforcement corrosion. The results demonstrate that the balanced incorporation of CS, IS, and RCA improves particle packing, matrix densification, interfacial bonding, and durability, while reducing natural resource consumption and industrial waste disposal. The proposed mix therefore offers a technically feasible and environmentally beneficial approach for sustainable concrete production.