Impact of Waste Iron Slag on Mechanical and Durability Properties of Concrete

Waste management is of great concern in today’s world. Every year, an enormous amount of solid waste is generated from different industrial activities, especially the waste which is produced by iron industries in a particular form of slag. The major issue of emission of carbon dioxide (CO2) from cement industries is a serious problem for the earth's environment and the surrounding area. Thus, in this study, the waste iron slag obtained from nearby iron industries was used as a partial substitute for cement. The cement was replaced with iron slag (IS) at the substitution levels of 7.5%, 15%, 22.5%, 30% and 37.5% by weight of cement. The doses of superplasticizer for every mix were taken based on the essential workability requirements for the reinforcedconcrete work. Performance of control and blended mixes was evaluated by workability evaluation, compressive strength test, flexural strength test, water permeability test, water absorption evaluation, rapid chloride penetration test (RCPT) and carbonation test. Scanning electron microscopy (SEM), X-ray diffraction (XRD) technique and thermogravimetric analysis (TGA) technique were used to assess the micro-structural changes and to evaluate the chemistry of the blended mixes. The results obtained from this study were encouraging in terms of compressive and flexural strengths. The maximum compressive and flexural strengths were recorded at a 22.5% replacement level of slag. The results obtained at 30% replacement were also better compared to the control mix. The resistance of slag-made concrete mixes against adverse conditions; i.e., CO2 penetration, chloride penetration and water penetration was far better than that of conventional ones. The results obtained from TGA indicated that the productivity of calcium silicate gel of slag concrete is better than that of control concrete. KEYWORDS: Concrete, Slag, Carbonization, RCPT, XRD, TGA, SEM.