Industrial copper waste as a sustainable material in high strength SCC

Abstract

The present study is focused on High strength self-compacting concrete (HS-SCC) using fly ash (FA) and copper slag (CS) as supplementary cementitious materials (SCM) as cement and fine aggregate replacement, respectively. Fly ash was initially replaced as 0, 5, 10, 15, 20, 25, and 30% by cement in M60 grade of concrete. The optimum content of fly ash was noticed to be 20% based on the highest compressive strength. Twelve different HS-SCC mixes were further used in the study by keeping the optimized content of FA as constant, by varying the CS at 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%. The objective of the study is to determine the optimum content of CS in high strength blended self-compacting concrete based on the compressive strength of the blended mix at various ages such as 28, 56, 90 and 180 days. The study was also focused on the durability aspects such as sorptivity, sulfate attack and advanced techniques such as rapid chloride ion penetration test to assess the chloride ion penetration into the concrete. The concrete specimens were also assessed for the homogeneity of concrete by performing an ultra-sonic pulse velocity test. Microstructural study of HS-SCC was performed with Scanning Electron Microscope (SEM) and X-Ray diffraction (XRD) techniques. The experimental studies show that fresh properties were improved with the increase of copper slag content. The maximum compressive strength was obtained at 40% copper slag substitution. Copper slag showed a significant effect on reduction of chloride penetration and increased in quality of concrete. Sulfate immersion increases the weight but a decline in compressive strength. This study recommends copper slag as a sustainable material to develop high strength self-compacting concrete(HS-SCC).