Experimental investigation on use of ferrochrome slag as an alternative to natural aggregates in concrete structures

In view of reducing the cost of concrete and to meet the demand of conventional raw materials used in concrete, various industrial and solid wastes are being studied for their utilization in concrete without affecting its fresh, hardened and durability properties. Ferrochrome slag is waste material obtained from manufacturing of high carbon ferrochromium alloy. Depending upon cooling process, two types of ferrochrome slag are produced i.e. air cooled by letting molten slag cooled down under normal temperature and water cooled ferrochrome slag by quenching molten slag. Presence of chromium in Cr+3 and Cr+6 state in ferrochrome slag is an area of concern towards its feasibility to be used as a constituent material in concrete. In this study, physical and chemical properties of both types of slags were evaluated to check the feasibility of replacing natural fine aggregates with water cooled ferrochrome slag and natural coarse aggregates with air cooled ferrochrome slag. In concrete mix designs, natural aggregates were replaced with ferrochrome slag at replacement levels of 30%, 60% and 100%. Mixes were prepared at two w/c ratios and were evaluated for different fresh, hardened and durability properties of concrete. It was concluded that 60% replacement of natural coarse aggregate with air cooled ferrochrome slag and 60% replacement of natural fine aggregate with water cooled ferrochrome slag in concrete is feasible.