Assessing the Efficacy of Alkali-Activated Rice Husk Ash Amended Bauxite Residue Composites for Pavement Applications

The study investigates the use of agricultural waste, i.e., Rice Husk Ash (RHA), in altering Bauxite Residue (BR) for pavement applications. Locally available natural soils (NS) was used for comparison. Samples were prepared with water and varying proportions of alkali activators, and their mechanical characteristics were examined through Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) tests. Microstructural analyses were carried out using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Heavy metal analysis was performed to assess environmental safety. Results showed that 95% BR with 5% RHA exhibited a remarkable UCS increase from 106.19 kPa (water) to 1247.78 kPa (alkali-activators). The CBR values confirmed superior strength under alkali activation. Both the UCS and CBR fulfilled the sub-base and subgrade requirements specified by standards. Morphological and mineralogical studies supported these improvements. The heavy metal concentrations in optimized samples were within the acceptable limit, further recommending it for field application.