Cupola slag as partial replacement of fine aggregate in concrete - An experimental study

Cupola slag is one of the industrial by-products obtained from cupola furnace which is a device usually used in foundry industries for the melting of metals. Cupola slag is underutilized and very few studies are documented in literature wherein cupola slag has been utilized in concrete production. An attempt has been made to examine the effectiveness of cupola slag, as a partial substitute to fine aggregates, on the mechanical and durability properties of concrete. Fine aggregate was replaced by cupola slag at five different percentages (0%, 10%, 20%, 30% and 40%). In addition, the w/c ratios varied were 0.40, 0.45 and 0.50 at a fixed cement content of 380 kg/m(3). Across all the concrete mixes and at all curing ages, an increase in the compressive strength was observed due to incorporation cupola slag up to 30% replacement level of fine aggregates after which a decrease in strength was observed on further addition of cupola slag. This increment in compressive strength was higher at lower w/c ratios. Similar trends were observed for split tensile strength. For all curing ages, a decrease in water penetration depth was observed with an increase in the percentage of cupola replacement (CR) from 0% to 40% and this decrease was most prominent at the w/c ratio of 0.4. Similarly, for all the aforesaid parameters a significant improvement of abrasion resistance in terms of reduction in wear depths was observed. Correlations were developed between strength and durability properties so as to validate the experimentally obtained results. To examine the 'effect' and 'size of effect' of CR percentage and w/c ratio on the concrete properties, two-way analysis of variance was carried out and statistically significant results were obtained. At all curing ages, quadratic relationships were developed for establishing the dependence of concrete properties on CR and w/c ratio. The results of this investigation indicate that cupola slag is a sustainable material which can be effectively used as partial substitute to natural sand.