Evaluation of Copper Slag as a Fine Aggregate Substitute in Concrete for Industrial Applications in Lagos State

This study evaluates the use of copper slag, a by-product of copper refining operations, as a partial and full substitute for river sand in concrete production for industrial floor slab applications in Lagos State, South West Nigeria. Lagos hosts Nigeria's highest concentration of secondary metal processing facilities and substantial copper slag deposits that are currently stockpiled without systematic utilisation. Copper slag samples are obtained from a recycling facility in Ikorodu, Lagos, and characterised for chemical composition, specific gravity, absorption, and surface texture by XRF, SSD absorption testing, and SEM. Concrete mixes are prepared with copper slag replacement at 0, 25, 50, 75, and 100 percent of fine aggregate by weight. Compressive strength, splitting tensile strength, flexural strength, and abrasion resistance are measured at 28 days. Results indicate that compressive strength increases progressively up to 75 percent copper slag replacement, achieving a 28-day value of 38 MPa compared to 31 MPa for the control mix, attributed to the superior packing density and angular particle shape of copper slag. Abrasion resistance also improves significantly, suggesting suitability for industrial floor applications. Workability decreases at higher copper slag contents due to reduced water absorption. The study recommends 50 to 75 percent copper slag replacement as optimal for industrial floor concrete in Lagos. Keywords: copper slag, fine aggregate, concrete, compressive strength, Lagos State.