Advancing Sustainability and Performance with Crushed Bottom Ash as Filler in Polymer-Modified Asphalt Concrete Mixtures.

Amid the growing demand for sustainable pavement solutions and the need to incorporate recycled materials into construction practices, this study explored the viability of using crushed thermal power plant bottom ash as a filler in polymer-modified asphalt concrete mixtures. Conventional lime filler was replaced with bottom ash at varying levels (0%, 25%, 50%, and 75%), and the resulting mixtures were evaluated using several performance tests. The optimal replacement level was determined to be 25%, based on the results of the indirect tensile strength (ITS) test. Comparisons between the control mixture and the 25% bottom ash-modified mixture were conducted using the dynamic modulus test, Cantabro test, Hamburg wheel tracking (HWT) test, and tensile strength ratio (TSR) test. The findings indicate that the 25% bottom ash-modified mixture demonstrated improved performance across multiple parameters. The HWT test showed enhanced rut durability, with a recorded depth of 7.56 mm compared to 8.9 mm for the control mixture. The Cantabro test results revealed lower weight loss percentages for the modified mixture, indicating better abrasion resistance. The dynamic modulus test indicated higher resilience and stiffness in both high- and low-frequency stages. The TSR test highlighted improved moisture resistance, with higher TSR values after 10 wet-drying cycles. These improvements are attributed to the fine particle size and beneficial chemical composition of bottom ash, which enhance the asphalt mixture's density, binder-aggregate adhesion, and overall durability. The results suggest that incorporating 25% crushed bottom ash as a filler in polymer-modified asphalt concrete mixtures is a viable and sustainable approach to improving pavement performance and longevity.