Strength and leaching characteristics of red mud (bauxite residue) as a geomaterial in synergy with fly ash and gypsum

Red mud (Bauxite residue) comprises microscopic particles and other chemical constituents that pose a major threat to the environment. The most common solution to resolve issues related to any solid waste is its reuse in construction. This paper delves into the possibility of using red mud as a geomaterial in synergy with fly ash and gypsum. In this regard upon finding the geotechnical properties of virgin red mud, it is strengthened with fly ash by replacing 10, 20, and 30% of red mud by its dry weight and to these combinations gypsum was added by 0.5% and 1% and prepared various combinations. The impact of these material additions on the characteristics of red mud were investigated using the Unconfined compressive strength and California bearing ratio values and their environmental compatibility was further studied by conducting the leaching characteristics using Toxicity Characteristics Leaching Procudure (TCLP) method. The findings of the tests indicated that fly ash and gypsum significantly enhanced the strength qualities of red mud as compared to unstabilized red mud. The stabilization helps red mud to attain a minimum strength required to use as a subgrade material. Furthermore, leaching investigations performed on stabilised samples have revealed that the vast majority of leaching heavy metals are within the WHO's authorised threshold for toxicity.