Suggested Citation:
Li, Hui, Ning Xie, Xue Zhang, Lijun Sun, John T. Harvey, Lei Wang (2025)

Investigation on Mixed Reflection Behavior of Cool Pavement Coating and Its Impact on Safety of Road Light Environment

. Institute of Transportation Studies, University of California, Davis, Journal Article UCD-ITS-RP-25-54

Abstract:

Due to low reflectance (5%–10%) of black asphalt pavement, most of the incident solar radiation (295–2500 nm) is absorbed and stored. This results in the high temperature (even exceeding 70 °C in summer) of the pavement surface, which leads to pavement diseases, exacerbates the heat island effect, and reduces human thermal comfort. Reflective pavement coating with high reflectance ranging from 20% to 80% is an effective way to solve the above problems. However, excessively improving the visible reflectance and ignoring the mixed reflection behavior (including specular and diffuse reflection properties) may cause glare problems and negatively affect road light environment safety. Therefore, precise control of reflectance is very significant. In this study, an automated test platform of reflection behavior was developed to investigate the mixed light reflection distribution pattern of reflective coating. Additionally, the impact of reflective coating on the light environment was explored. It was found that there was obvious specular reflection under conditions of a low incidence angle (less than 10°). Moreover, reflective coating could change the lightness index and specular reflection coefficient of traditional pavement. Finally, considering glare during the daytime and the nighttime illumination safety, the control indexes of reflective pavement coating were proposed. The visible reflectance and specular reflection coefficient should be lower than 22% and 1.5, respectively. The results will provide a theoretical basis for the precise and safe design of reflective pavement coatings. The coatings aim to improve the thermal and light environments, thereby enhancing driving safety, while also providing better illumination during emergency repair and maintenance of road infrastructure.