Light scattering from asphalt pavements: A review of measurement, factors, and modeling

The light scattering performance of asphalt pavement describes its ability to scatter incident light, which is crucial for driving safety, comfort, and maintaining a cooler near-surface environment. Although the use of light-colored aggregates and nano-optical modifiers can significantly enhance the light scattering performance of asphalt pavements, research gaps remain regarding its influencing factors and prediction models, due to the temporal variations in pavement materials and the operational environment. This paper reviews 125 studies on asphalt pavement light scattering, providing an in-depth summary of four key aspects: mechanisms, measurement methods, influencing factors, and related models. The results show that: (1) the light scattering properties of pavement can be effectively improved by optimizing the color and surface morphology of pavement. At the same time, the structural design of pavement additives can reduce glare (visible light reflectance <22%) and lower the pavement's thermal absorption in the near-infrared range (cooling >11℃). The research on asphalt pavement surface reconstruction models and solar radiation models has formed a relatively perfect technical system. Among the light scattering models, the Kirchhoff approximation, geometric optics ray tracing method, and four-dimensional bi-directional reflectance distribution function (BRDF) scattering model have been verified to have high simulation accuracy in simulating the light scattering from asphalt pavements (the accuracy is more than 95% under specific conditions). In addition, the shielding effects of factors such as clouds, roadside vertical buildings and trees on incident radiation exhibit seasonal periodicity.