Enhancement of strength and microstructural characterization in red mud-iron carbonate binders: Effects of CO2 sequestration and oxalic acid concentration

• A novel binder with red mud and iron powder as source material • Red mud-iron carbonate binders with oxalic acid enhance CO 2 sequestration • CO 2 curing technique can reduce CO 2 emission and enhances iron carbonate biner strength. • Extended CO 2 curing durations enhance the matrix strength formation in Redmud-based iron carbonate binders. This study explores the use of industrial waste products and carbon sequestration techniques to examine sustainable alternatives to traditional cement-based building materials. Previous studies demonstrate the performance of iron carbonate-based binders in the presence of fly ash and other pozzolanic material, but red mud (RM) as an addition to the iron carbonate matrix is a novel approach, which this study has aimed to address. This investigation primarily uses iron powder, red mud, metakaolin, and calcium carbonate. Oxalic acid is added at varying concentrations (0.5M, 1M, 1.5M, and 2M) to the binder matrix, and CO 2 curing is performed for 3 days and 6 days. The CO 2 -cured samples are compared with non-cured samples. The samples are tested for their flow, strength, and microstructural characterization. Results indicate that higher oxalic acid concentrations (1.5M and 2M) increase viscosity and reduce flowability, while 0.5M oxalic acid enhances the binder's workability. The compressive strength is the highest in 0.5M oxalic acid after 3 days of CO 2 curing and 1M oxalic acid after 6 days of CO 2 curing. This study shows that lower oxalic acid concentrations and extended CO 2 curing foster the formation of dense carbonate phases, such as siderite and calcite, enhancing matrix density and reducing pores, thereby enhancing strength development.