Thermo-Rheological Characterization and Performance Evaluation of Sustainable TiO2-Modified Hot Mix Asphalt (HMA) Formulations for Urban Pavement Infrastructure

Urban heat islands (UHIs), exacerbated by conventional asphalt pavements that absorb up to 95% of solar radiation, elevate urban temperatures, energy demands, and air pollution. To mitigate UHI effects, this study investigates the thermal and mechanical performance of asphalt pavements modified with titanium dioxide (TiO₂), a photocatalytic pigment that enhances solar reflectance and promotes surface cooling. The physicochemical properties of reference and TiO₂ modified asphalt mastics were evaluated, including penetration, softening point, and rheo-logical behavior (rutting resistance via G*/sinδ and fatigue performance via G*·sinδ). Aging effects were assessed through controlled UV and oxidative exposure. Results demonstrate that TiO₂ incorporation increased solar reflectance by 45,5% in 12 months, reducing surface temperatures by up to 8°C compared to conventional asphalt pavement. This cooling effect, attributed to TiO₂’s dual role as a photon-reflective and photocatalytic material, was maintained even after aging, with the solar reflectance increasing under outdoors environmental degradation. Mechanically, the modified mastic exhibited comparable rutting resistance and enhanced fatigue performance to reference mastic. Furthermore, TiO₂ modified specimens demonstrated enhanced moisture resistance (modified Lottman test) and retained deformation resistance comparable to conventional asphalt mixture in wheel tracking tests. These findings position TiO₂ modified asphalt mastic as a multifunctional solution for UHI mitigation, combining passive radiative cooling, photocatalytic pollution reduction, and robust pavement performance. Future work should optimize TiO₂ dispersion protocols and evaluate long-term cost-benefit ratios for scalable urban implementation.