Investigating geopolymer mortar incorporating industrial waste using response surface methodology: A sustainable approach for construction materials

The environmental impact of conventional cement production necessitates sustainable alternatives in construction materials. Replacing cement mortars with geopolymer mortars offers a promising approach. This study focuses on geopolymer mortars as a potential solution by incorporating industrial waste, specifically red mud (RM), as a partial substitute for aluminosilicate materials. In fact, this research investigating the influence of RM content, curing temperature, and alkaline solution concentrations on GGBS-based geopolymer mortar properties. The findings suggest that replacing RM in GGBS-based geopolymer mortars can extend their setting time, addressing a key limitation. However, an increase in RM content correlates with decreased mortar workability. Additionally, to illustrate the properties of hardened mortar, Response Surface Methodology (RSM) was employed. The RSM modeling results indicate that water absorption increases with increasing RM content but remains relatively unaffected by solution concentration or curing temperature. Importantly, incorporating RM consistently decreases the compressive strength of the mortar. However, the results demonstrate that for RM-containing specimens, the compressive strength reaches its peak at a curing temperature of 44°C and declines at higher temperatures. Moreover, the optimization results indicate that a sodium hydroxide solution with a molarity of approximately 11 M yields the optimal balance of higher strength and lower water absorption. Furthermore, FTIR and SEM/EDS analysis provide insights into the chemical composition and microstructure of the mortars, elucidating the intricate relationship between their composition and performance.