Study on the Photothermal Performance of a "Thermal Shielding" Coating Using Tungsten Bronze as Functional Material for Asphalt Pavement

Asphalt pavements absorb more than 90% of the incident solar radiation, which induces not only high-temperature degradation but also the urban heat island (UHI) effect. In this study, a novel nanoscale non-stoichiometric compound containing tungsten (M_xWO₃) was used for the first time to prepare thermal shielding coatings to reduce the temperature of pavements and mitigate the UHI effect. Coatings with good shielding characteristics were selected for outdoor thermal insulation tests to evaluate their properties. M_xWO₃ (M = K, Na, Cs) exhibited significant thermal shielding, especially Cs_xWO₃. Outdoor thermal insulation tests were performed for the Cs_xWO₃ coatings, and it was found that the greater the doping, the more significant the thermal shielding effect. Compared with untreated pavements, the surface-coated pavement exhibited significant cooling at 5 cm and 15 cm depth-wise, which reduced the overall pavement temperature by 1-2 °C, and the coating thickness affected the cooling effect.