Study on component optical properties and photoaging behavior mechanism for asphalt binders

To investigate the potential relationship of component optical properties and performance degradation for asphalt binders, molecular dynamics (MD) and scanning electron microscopy (SEM) were used to study the optical absorption spectral characteristics and evolution mechanism of components molecules. Firstly, based on the natural light aging test of asphalt binders, the unaged, short-term aged and long-term aged asphalt samples were obtained, and the reliable asphalt component models and asphalt micro models were determined. Secondly, the component optical properties of asphalt binders were analyzed by MD simulation, and the evolution mechanism of optical properties for asphalt binders was explored by combining with its electrostatic potential and functional group characteristics. Finally, the rationality of MD simulation can be proved by asphalt SEM tests, and the component optical properties of asphalt binders and the photoaging behavior mechanism can be further analyzed. Studies have shown that different component molecules have different optical absorption spectral characteristic, and the optical absorption spectra of aged components tend to be in the relatively long-wave region, the surface micro topography characteristics include larger roughness, larger fluctuation range and larger microsurface area. Excluding other environmental factors, the photoaging behavior of asphalt binders can be affected by the optical absorption spectrum range and intensity, component proportion, solar radiation flux. The results explain the photoaging behavior mechanism of asphalt binders from the perspective of component optical properties, which can provide theoretical basis for strengthening the anti-photoaging properties of asphalt binders.