Critical analysis of using recycled wax oils in asphalt binder considering exudation effects

The tendency of asphalt to exude oil under certain conditions is often overlooked as a form of aging in asphalt pavement. To better understand the issue of oil exudation in asphalt during long term cold storage, two different oil sources of asphalt binders with recycled wax oils were investigated using the extended bending beam rheometer test (Ex-BBR), double edge notched tension test (DENT), extended Hansen solubility model, and fluorescence and polarizing microscopy. The results of the Ex-BBR and DENT tests demonstrate that the addition of recycled wax oils significantly enhances the low-temperature performance of asphalt. However, the use of fluorescing markers in cooling media indicates that recycled wax oil exudation can lead to ethanol diffusion in the asphalt binder. To further elucidate the factors influencing exudation, a device for accelerating the exudation of asphalt was developed. The research results show that, in addition to the intrinsic properties of asphalt and recycled wax oils, pressure, time, and temperature significantly influence the acceleration of exudation. The primary changes in recycled wax oil exudation occur early on, with the exudation rate decreasing over time. The fluorescent microscope reveals the separation of recycled wax oils as a fluorescent ring. Recycled wax oils alter the internal stability of asphalt, as evidenced by an increase in polarity and hydrogen bonding. This change is expected to impact the compatibility of asphalt binders. The mechanism of these interactions varies significantly depending on the source of the asphalt binder. After accelerated exudation, the three interaction forces representing sensitivity to chemical environments are further reduced.