Utilization of copper slag and Metakaolin in Geopolymer concrete synthesis

Lorna Njenga

This research investigates the viability of utilizing Copper Slag (CS), a mining waste, and Metakaolin (MK) as precursors in geopolymer concrete (GPC) synthesis, particularly for application in African countries such as the Democratic Republic of Congo (DRC) and Zambia, where copper smelting waste is abundant. Copper Slag, a by-product of pyrometallurgical extraction, was sourced from the Nkana slag dump in Zambia and processed through crushing, grinding, and sieving. MK was derived from natural kaolinite deposits in Western Australia and calcined to enhance its amorphous content from Kaolin. Four mix designs were explored: 100% CS, 100% MK, 70% CS – 30% MK, and 50% CS– 50% MK. A constant A/B ratio of 0.5 and an alkali solution of 8M were maintained across all the mix designs. Experimental methods included mineralogical (XRD), morphological (SEM), and chemical (FTIR) characterization of the raw materials. Compressive strength was tested at 7, 14, and 21 days. Preliminary findings from material characterization support CS's potential to serve as a durable and eco-friendly binder when supplemented with MK. The findings also conclusively indicate that blending CS with MK effectively leverages the limitations of each material, resulting in an optimized and superior-performing geopolymer. Of all the mix designs, 50% CS-50% MK achieved the best results with a compressive strength of 35.59 MPa under oven curing and had better workability. In contrast, 100% CS showed the weakest performance. 100% MK had the highest compressive strength but poor workability. The research contributes to environmental sustainability and circular economy goals by valorising mining waste into high-performance construction material. The results are promising for regions with abundant CS waste and offer a viable alternative to Ordinary Portland Cement.

Utilization of copper slag and Metakaolin in Geopolymer concrete synthesis

Files and links (1)

Abstract

Details

Metrics