Thermal and Electrical Conductivity of Modified Asphalt Mixes Reinforced with Waste Tyre Metal Fiber and Graphite

Asphalt is a vital material in road construction due to its durability and flexibility. However, conventional asphalt mixtures often face performance challenges, such as cracking, rutting, and thermal deformation under heavy traffic loads and temperature fluctuations. This study aims to enhance the thermal and electrical conductivity of asphalt mixtures by incorporating Waste Tire Metal Fiber (WTMF) and Graphite, thereby improving overall performance and pavement longevity. The study begins with the evaluation of volumetric properties and Optimum Bitumen Content (OBC) of the control mix, which was determined to be 4.9%, in compliance with Jabatan Kerja Raya (JKR) specifications. Modified asphalt samples with 0.2%, 0.5%, and 1.0% WTMF and 1.0%, 3.0%, and 5.0% graphite were prepared and tested for Marshall stability, flow, volumetric properties, electrical resistivity, and thermal conductivity. Results showed that air voids (AV) increased with higher WTMF content, while voids filled with bitumen (VFB) decreased. Stability values decreased beyond 0.5% WTMF, while graphite-modified samples improved stability up to 3.0% graphite. For conductivity properties, electrical resistivity decreased by 92% (1.0% WTMF) and 72% (5.0% graphite), while thermal conductivity improved by 56% and 48%, respectively. The optimal composition of 0.5% WTMF and 3.0% graphite achieved the best balance between conductivity enhancement and mechanical performance, paving the way for resilient, sustainable asphalt pavement solutions. Future work will focus on enhancing fiber distribution and further optimizing bitumen content to maximize long-term performance.