ARCHIVES

Rapid industrial development and growing construction activity have created significant volumes of waste materials that strain landfills and deplete natural aggregate resources. Steel slag, a by-product of steel manufacturing, is durable, hard, and highly resistant to biological, chemical, and physical degradation, presenting a viable alternative to conventional coarse aggregate. This study investigates the compressive strength of M30 grade concrete when natural coarse aggregate is replaced with steel slag at 10%, 20%, 30%, 40%, and 50% by volume. Standard 150 mm × 150 mm × 150 mm cube specimens were cast and tested at 7, 14, and 28 days in accordance with IS 516-1965. The results demonstrate that compressive strength increases progressively from 10% to 30% replacement, with 30% replacement achieving the peak compressive strength at all test ages. Beyond 30%, strength declines noticeably, making 20%–30% replacement the optimal range. The findings support the use of steel slag as an economical, environment-friendly coarse aggregate substitute that helps divert industrial waste from landfills while maintaining or enhancing concrete performance.