Copper slag from different dumps in the Atacama Region used in mortars as partial replacement of cement

Abstract

The use of copper slag as a partial substitute for cement in mortar preparation was studied. Copper slag samples were collected from three dumps in the Atacama Region (Northern Chile). Mortars of 40x40x160 mm (width, height, length) and curing times of 7, 28 and 90 days were used in mechanical testing. Tests were performed with 0% (control mortar), 5, 10, 15 and 20% copper slag as partial replacement of cement. The results of mechanical tests showed a gradual increase in compressive and flexural strength at 7, 28 and 90 days in mortars containing copper slag when compared with the control mortar. The major differences between the control and copper slag mortars are evident after 7 days, which indicates that the presence of slag in the blends has a retardant effect on the hardening process. On the other hand, at 90 days, compressive and flexural strength was very similar for both control mortar and mortars containing copper slag. Optimal compressive and flexural strength values are achieved with 5% of cement substitution by copper slag. The study concludes that the use of copper slag in mortars presents a viable alternative for partial cement replacement, and also contributes to mitigate adverse environmental effects of copper mining.