Use of Copper Slag and Fly Ash in High Strength Concrete

An experimental investigation was conducted to study the effect of using copper slag as a fine aggregate and the effect fly ash as partial replacement of cement on the properties high strength concrete. Totally ten concrete mixtures were prepared. Five mixes containing different proportions of copper slag ranging from 0 % (for the control mix) to 75 %. Five mixes containing fly ash as partial replacement of cement ranging from 6 % to 30 % (all 5 mixes contains 50 % copper slag as sand replacements). Concrete mixes were tested for workability, density, compressive strength, tensile strength, flexural strength. The results indicate that there is a slight increase in the density of nearly 6 % with the increase of copper slag content, whereas the workability increased with increase in copper slag percentage. Addition of up to 50 % of copper slag as sand replacement yielded comparable strength with that of the control mix. However, further additions of copper slag caused reduction in the strength due to an increase of the free water content in the mix. Mix with 75 % copper slag replacement gave the lowest compressive strength value of approximately 80 MPa, 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 for better strength. Introduction of fly ash gave better results than concrete containing 50 % copper slag. The strength has increased approximately 4 % containing 18 % fly ash and decreased with further replacements of cement with fly ash. Whereas, workability got increased with further increase in fly ash content. Therefore, it is recommended 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.