Strength Determination of High Strength Concrete Blended with Copper Slag and Fly Ash

An experimental analysis was conducted to study the effects of using copper slag as a fine aggregate (FA) and the effect of fly ash as partial replacement of cement on the properties high strength concrete. In this analysis total ten concrete mixtures were prepared, out of which five mixes containing different proportions of copper slag ranging from 0% (for the control mix) to 75% were prepared and remaining five mixes containing fly ash as partial replacement of cement ranging from 6% to 30% (all mixes contains 50% copper slag as sand replacements). Concrete matrix were tested for compressive strength, tensile strength and flexural strength tests. Addition of copper slag as sand replacement up to 50% yielded comparable strength with that of the control matrix. However, further additions of copper slag, caused reduction in strength due to an increment of the free water content in the mix. Concrete mix with 75% copper slag replacement gave the lowest compressive strength value of approximately 80 MPa at 28 days curing period, which is almost 4% more than the strength of the control mix. For this concrete containing 50% copper slag, fly ash is introduced in the concrete to achieve the better compressive, split and flexural strengths. It was also observed that, introduction of the fly ash gave better results than concrete containing 50% copper slag. When concrete prepared with 18 % of fly ash, the strength has increased approximately 4%, and strength decreased with further replacements of the cement with fly ash. Hence, it is suggested that 50% of copper slag can be used as replacement of sand and 18% fly ash can be used as replacement of cement in order to obtain high strength concrete.