Abstract
Urban Heat Island (UHI) phenomena lead to elevated surface temperatures, increased energy consumption, and accelerated pavement degradation. This study aims to enhance the thermal and mechanical performance of asphalt mixtures by incorporating fly ash (FA), a byproduct of coal combustion, as a partial replacement for cement. Asphalt mixtures were prepared using various FA contents (0%, 2%, 4%, 6%) through the dry mixing method. Thermal conductivity was evaluated using the QTM-500 device, while Marshall tests assessed mechanical stability. Results showed that 6% FA reduced thermal conductivity by 20.13%, whereas 4% FA provided the best balance between thermal insulation and structural stability. A clear inverse relationship was observed between thermal conductivity and properties such as bulk density, Marshall stability, and air voids, indicating that FA can enhance insulation without compromising durability. The study focused on the surface asphalt layer, as it serves as the primary interface for solar radiation and heat exchange. Improving its thermal behavior reduces heat transfer to underlying layers, thereby extending pavement lifespan. Moreover, these improvements contribute to mitigating UHI effects, by lowering heat absorption during the day and minimizing heat retention at night supporting sustainable urban development.