Holistic characterisation of rice husk ash-modified asphalt: Integrating chemical, thermal, and rheological perspectives

: Rice Husk Ash (RHA), an agro-industrial byproduct, has recently gained global attention as a promising asphalt modifier, owing to its potential to improve the asphalt performance while promoting waste valorisation. Although previous studies have predominantly focused on the high-temperature performance of RHA-modified asphalt (RMA), its behaviour under intermediate and low temperatures remains largely unexplored. Moreover, the interlinking of the physicochemical properties of RMA with asphalt performance is still unclear. This study aimed to investigate the physicochemical, thermal, and viscoelastic properties of RMA and evaluate its performance over a wide range of temperatures and frequencies using advanced micro-level characterisation techniques and potential rheological parameters. Thermal sensitivity and workability of RMA were analysed using the consistency indices and activation energy concepts. Cole-Cole plots, master curves, and black space diagrams were effectively utilised to evaluate the rheological behaviour and performance characteristics of RMA. Furthermore, the significance of the key findings concluded from the experimental analyses was statistically assessed using MANOVA. Overall, it was observed that RHA incorporation impacts the physicochemical, thermal, and viscoelastic properties of asphalt, leading to its potential usage in high temperatures and controlled usage in intermediate and low-temperature regions.