Geotechnical Behaviour of Bauxite Residue (Red Mud): A Review of Global Parameter Variability and Chemical–Mechanical Interactions

Bauxite residue (red mud) is a highly alkaline byproduct of the alumina refining process generated in large volumes worldwide. Most alumina operations currently rely on long-term storage facilities due to the high costs and technical constraints of residue reuse technologies. Therefore, understanding the mechanical behaviour of bauxite residue is critical to minimising environmental contamination risks, preventing structural failures, and ensuring the long-term stability of storage facilities. However, obtaining reliable geotechnical parameters is challenging due to the residue’s complex composition and chemical characteristics, particularly given the current fragmented state of the literature. This review compiles an extensive database of bauxite residue parameters across alumina operations worldwide, synthesising existing knowledge and research needs. The database encompasses 940 data points extracted from 63 studies across 25 countries. The findings reveal considerable variability in parameter values across countries, potentially exacerbated by inconsistencies in experimental methodologies. Few studies have integrated geochemical conditions, such as pH and salinity, with geomechanical behaviour, thereby limiting understanding of the mechanisms that govern key parameters, including strength and deformability. Enhancing the predictability of bauxite residue behaviour requires the development of standardised experimental protocols that explicitly account for the coupled effects of chemistry and mechanics to support reliable risk assessments of storage facilities.