Utilization of aluminum sludge (AS) to enhance mine tailings-based geopolymer

This paper investigates the feasibility of using aluminum sludge (AS) to enhance copper mine tailings (MT)-based geopolymer. The Si/Al and Na/Al molar ratios were adjusted by adding AS into the high silica content MT and using different amounts of NaOH. Unconfined compression tests and SEM, XRD, and FTIR studies were conducted on geopolymer specimens prepared at different Si/Al and Na/Al ratios and after 7-day curing. The results indicate that by adding AS and utilizing appropriate amount of NaOH, the unconfined compressive strength increases significantly. The main reason is because the addition of AS along with utilization of appropriate amount of NaOH makes both the Si/Al and Na/Al ratios reach the optimum values for geopolymerization, leading to higher degree of geopolymerization and more compact geopolymer microstructure. Based on this study, it can be concluded that AS can be used to effectively enhance the MT-based geopolymer.