Mechanical Properties and Durability of Concrete with Water Cooled Copper Slag Aggregate

Copper slag is a voluminous waste material obtained during the manufacturing of copper (matte smelting process). As its disposal becomes a concern for environmental protection agencies and governments, possible alternative outlets for this waste material are needed. The paper presents a laboratory study on CEM-II concrete mixes, containing water-cooled copper slag waste material for a partial or full replacement of fine concrete aggregate. A series of tests were performed at two different water to cement ratios, to determine the workability, cube compressive strength, indirect tensile strength, static modulus of elasticity, and a number of durability-related characteristics (water absorption, accelerated corrosion, carbonation, alkali-silica reaction). The results showed that water-cooled copper slag had variable effects on the resulting fresh or hardened concrete properties, depending on the sand replacement level and water to cement ratio. However the measured strength values were likely to be linked to the usual variability of concrete batches, rather than a significant effect of the copper slag aggregate. This hypothesis was further supported by statistical analysis. Concerning the durability related characteristics, the overall performance of the concrete containing copper-slag was in most cases similar or better than that of normal concrete with natural sand aggregate. Based on the results water-cooled copper slag can therefore be considered to be a suitable fine aggregate for concrete. This shows promise for developing an additional viable solution to tackle the issue of copper slag waste.