A systematic characterization of the mixture of red mud and bottom ash as a geomaterial: an efficient utilization in subgrade pavement.

Red mud and bottom ash are two industrial wastes generated in huge quantities by the aluminum industry and coal-based power plants, worldwide. The high alkaline nature and high specific gravity of red mud are the major hindrances in utilizing as constructional geomaterial. The manuscript aims to utilize these two wastes as subgrade material in pavement by mixing different proportions of red mud with bottom ash. The physical behavior i.e., specific gravity, grain size pattern, and chemical characterization i.e., pH of all the mixes were assessed. Geotechnical properties such as compaction, compression, strength, and permeability tests were conducted to investigate the efficiency of different mixes as suitable geomaterial. The California bearing ratio, cyclic triaxial test under different confining pressure, resilient modulus, and nonactivity of clays by methylene blue test results provide the proficiency of different mixes in utilizing as subgrade material. The highest strength, high CBR, and resilient modulus values suggest that the mixture of 70% HRM with 30% HBA is suitable and strength gain upon drying suggests that it can be used as a structural subgrade material. Further, a leachate analysis of all the mixes concluded that the chemicals are within permissible limits and hence not hazardous to the ecosystem. [ABSTRACT FROM AUTHOR]