Evaluation of tensile, rutting and fatigue performance of asphalt mastic utilizing paper sludge ash as an alternative filler

Paper-sludge-ash a byproduct of the paper industry, is generated globally, exceeding 200 million tonnes/year, creating a disposal challenge. This study investigates the impact of Paper-sludge-ash as an alternative filler in asphalt mastic by replacing conventional basalt filler at 0%, 10%, 15%, 20%, and 25% by mass, while keeping a constant filler-to-binder ratio of 0.8. An in-depth characterisation of Paper-sludge-ash confirmed similar physiochemical characteristics to conventional fillers. Rheological and mechanical performance were assessed (across low-medium-high temperatures); through force-ductility, rutting resistance through Superpave-rutting parameter and Multiple-stress-creep-recovery, and fatigue behaviour by using Superpave-fatigue-parameter and Linear Amplitude Sweep tests based on the Viscoelastic-continuum damage framework. Obtained results indicate that, utilisation of 20–25% Paper-sludge-ash increased tensile deformation energy by 26.6%, improved rutting resistance by 2.7 times, and extended fatigue life in comparison to conventional basalt-filler mastic. These findings demonstrate the potential of Paper-sludge-ash as a high-performance and low-carbon alternative for sustainable pavement applications.