Utilization of Copper Smelting By-Product as a Sand Substitute in High-Performance Concrete

·        The workability of concrete improved consistently with an increase in copper slag content due to its smooth surface texture and low water absorption. However, very high workability at 80–100% replacement may lead to segregation and bleeding. ·        The optimum compressive strength was achieved at 40% replacement (78 MPa at 28 days), showing about a 15% improvement over the control mix. Strength values declined beyond 60% replacement. ·        Split tensile strength followed a similar trend, with a maximum of 5.4 MPa at 40% replacement, indicating enhanced resistance to cracking up to moderate replacement levels. ·        Flexural strength also improved with copper slag, peaking at 9.3 MPa at 40% replacement. This demonstrates that copper slag enhances the bending resistance of high-strength concrete at moderate levels. ·        Beyond 60% replacement, all strength properties showed a decline due to weak interfacial bonding and the presence of excess free water. ·        Overall, 40–60% replacement of fine aggregate with copper slag can be recommended as the optimum range for M60 grade high-strength concrete. ·        The use of copper slag not only enhances mechanical performance but also addresses sustainability concerns by reducing reliance on natural sand and enabling effective disposal of industrial by-products. ·        Economically, copper slag offers a cost-effective alternative to natural sand, especially in regions where it is locally available

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