Utilization of agricultural waste-based fillers from rice husk ash and bagasse ash in asphalt concrete-binder course (AC-BC) pavement

The increasing emphasis on sustainable infrastructure has prompted the utilization of alternative and eco-friendly materials in pavement construction. This study investigates the potential use of rice husk ash (RHA) and Bagasse ash (BA), both agricultural waste by-products, as alternative fillers in Asphalt Concrete–Binder Course (AC-BC) mixtures. A quantitative experimental approach was used, involving laboratory tests on aggregates, asphalt, and fillers, followed by Marshall testing. Filler contents of 0%, 2%, 4%, 6%, and 8% were evaluated for stability, flow, void in mix (VIM), voids in mineral aggregate (VMA), voids filled with bitumen (VFB), and Marshall Quotient (MQ). The optimum asphalt content was 6.65%. Results showed that BA improved the mixtures mechanical properties, especially at 4% filler, achieves the highest stability and MQ. RHA performed well at lower levels, but excessive use increased stiffness and risk of cracking. Both fillers meet Indonesian National Standard (SNI) specifications, proving their technical feasibility. Furthermore, their application contributes to waste reduction and environmental sustainability by recycling biomass waste into valuable construction materials. This research confirms that RHA and BA are promising eco-friendly alternatives to conventional mineral fillers, aligning with sustainable infrastructure goals without compromising the structural integrity of pavement layers.