Cooling efficiency of thermochromic asphalt pavement material and its contribution to field performance enhancement of asphalt mixture

The thermochromic asphalt pavement material (TAPM) has the potential to bilaterally regulate the pavement temperature according to seasonal environment, which is beneficial to heat island effect mitigation and pavement performance enhancement. However, studies on quantifying the cooling efficiency and verifying the field performance of TAPM are still limited. This study aims to more extensively verify the cooling efficiency of TAPM in different climatic regions and to reveal its cooling mechanism in the field. The key thermophysical parameter, solar albedo, of TAPM was back-calculated using an interpolation methodology to match the numerical simulation results with the specimen temperature data monitored experimentally. The cooling efficiency of TAPM in broader climatic regions was demonstrated through the numerical simulation combined with real meteorological conditions. In view of the cooling characteristics of TAPM as well as the temperature dependency attribute of asphalt mixture, various field performance properties of TAPM were characterized. It was found that at a temperature larger than 31 ℃, the solar albedo of TAPM is 0.30, which is six times larger than that of the conventional asphalt pavement material, indicating a strong reflection ability to solar radiation. The average temperature reduction of TAPM compared with the conventional asphalt pavement material in different regions is 6.26 ℃ with a standard deviation of 0.79 ℃, demonstrating the effective, universal and stable cooling effect of TAPM in summer across China. The cooling function of TAPM contributes to the improvement of high-temperature stability, aging resistance and low-temperature cracking performance of asphalt mixture. Therefore, it is necessary to consider the unique cooling function of TAPM for a more objective evaluation of its field performance.