The building industry significantly contributes to natural resource depletion and environmental imbalances through unregulated mining activities. To address the sustainability challenges associated with concrete manufacturing, this study evaluates the potential of industrial by-products, such as imperial smelting furnace (ISF) slag, fly ash, and nanosilica, as partial replacements for fine aggregates in concrete. The physical and mechanical properties of these industrial wastes were assessed, and their effects on concrete performance were systematically compared. The investigation showed that ISF slag, due to its higher specific gravity, significantly enhances the density and mechanical properties of concrete, with compressive strength reaching up to 56.17 MPa at a 40% replacement level. Fly ash demonstrated a steady increase in compressive strength, peaking at 40 MPa with a 50% replacement. Nanosilica also improved the compressive strength, achieving 40.22 MPa at a 50% replacement. The study concludes that incorporating these industrial by-products not only mitigates environmental impacts but also produces concrete with superior mechanical properties, making it suitable for various infrastructure applications. These findings underscore the viability of using ISF slag, fly ash, and nanosilica as sustainable alternatives to natural sand in concrete formulations.