Utilization of Steel Slag in Concrete as a Partial Replacement to Fine Aggregate

Concrete is largest produced material in the construction industry and as per WHO concrete is the largest consumed material by human beings after food and water. About 75% of the concrete is composed of aggregates and because of huge demand of concrete all over the world, availability of natural aggregates is becoming scarce. Civil engineers have always been looking for an alternative for the use of more eco-friendly and easily available materials as a replacement to conventional constituents in concrete. Concrete industry has always welcomed the use of various industrial waste materials as a replacement to these constituents since, otherwise such industrial waste need to be disposed in the form of landfills causing enormous amount of land pollution. This project presents the experimental investigation carried out to evaluate the effect of partial replacement of fine aggregate in concrete by steel slag which is waste product generated during the production of steel. The use of steel slag reduces the need of natural rock as constructional material, hence preserving our natural rock resources besides provides an environmental friendly option of concrete production. Steel slag mainly consists of calcium carbonate and is produced as a by-product of oxidation process in steel industry. The primary aim of this study is to evaluate the various properties of a concrete, obtained by partial replacement of fine aggregate by steel slag. In this research, apart from cement, fly ash and metakoalin (as a partial replacement to cement) were used as binding material. Five sample mixes were taken whose compression tests, tensile tests, sorptivity and water absorption tests were conducted. The mixes were obtained with 0, 30 and 40 percent replacement of fine aggregate by steel slag besides using different percentage replacements (25% of cement by fly ash in three trials, 15% and 10% cement by fly ash and metakoalin respectively in other two trials) of cement by pozzalonas. The experimental results were plotted and compared. It was observed that compressive and tensile strength increased with the increase in steel slag percentage upto to certain limit (30%). Increasing the percentage to 40% there was a sharp decline in magnitude of strength parameters and furthermore increasing metakoalin content had an effect of increasing strength. Capillary rise and water absorption increased with addition of steel slag and decreased with increase in metaloalin content.