Use of Recycled Copper Slag in Cement-Treated Singapore Marine Clay

Abstract

Copper slag is a by-product obtained during the matte smelting and refining of copper. Singapore imports huge amount of copper slag to be used as abrasive material for ship clearing and repairing, and resulting in used copper slag as waste material. It has been estimated that 300,000 tonnes of copper slag needs to be disposed annually. Singapore being an island country and having shortage of landfill space, hence copper slag disposal becomes an environmental problem. The objective of this research is to study the possible pozzolanic property of this used copper slag to see if it can be effectively used as a partial cement substitute and partial soil replacement in cement-treated soft clay. If so, it will be solving environmental problem on one hand, and strengthening soft clay at the same time. In this paper the effect of copper slag on strength characteristics of cement-treated Singapore marine clay is studied by varying the percentage of copper slag at 100% water content and constant workability of cement-clay mix. The results show that when workability of cement-treated clay with and without copper slag is kept constant, the unconfined compressive strength at 28 days curing time is observed to be constant. Therefore it seems to suggest that copper slag can be used in treating soft marine clay with less amount of cement and yet no reduction in strength can be achieved.