Performance and Environmental Evaluation of Incinerated Bottom Ash as Fine Aggregate in Asphalt Mix

Abstract: The growing scarcity of natural aggregates and the pressing need for sustainable waste management solutions have spurred interest in using Municipal Solid Waste Incineration Bottom Ash (MSWI-BA) in road construction. This study investigates the feasibility and performance of replacing fine aggregates with MSWI-BA in Bituminous Concrete Grade II (BC-II) mixes, with replacement levels ranging from 0% to 50%. Results demonstrate that MSWI-BA incorporation increases the optimum binder content due to its higher porosity but yields significant improvements in crucial pavement performance properties at moderate replacement levels. A 20% replacement of fine aggregates with MSWI-BA was found to provide an optimal balance between Marshall Stability, flow, stiffness, and moisture resistance, all while complying with Ministry of Road Transport and Highways (MoRT&H) standards. Although higher MSWI-BA levels increased rutting susceptibility and mix brittleness, up to 30% replacement levels still showed acceptable performance. Furthermore, environmental assessments through the Toxicity Characteristic Leaching Procedure (TCLP) confirmed that MSWI-BA is non-hazardous, with no significant leaching of harmful substances. This research demonstrates that up to 20% MSWI-BA incorporation into BC-II mixes enhances pavement performance while mitigating environmental impact, presenting a sustainable alternative to natural aggregates. However, further investigation into long-term field performance is recommended to harness the potential of MSWI-BA in road construction fully.