Molecular dynamics study on improvement effect of bis(2-hydroxyethyl) terephthalate on adhesive properties of asphalt-aggregate interface

The objectives of this study include the development of an environmentally friendly anti-stripping agent for asphalt, and prediction and evaluation of the improvement effect of this agent on the cohesive and adhesive properties of an asphalt mixture based on molecular dynamics simulation. Bis(2-hydroxyethyl) terephthalate (BHET), achieved through the depolymerization of main urban waste (polyethylene terephthalate (PET)), was blended with asphalt to build an asphalt/BHET model for the first time. Moreover, a representative acidic aggregate (granite) was adopted to construct an asphalt-aggregate interface model. Based on a reasonable model, the cohesive energy density (CED) was adopted to predict the cohesion property of asphalt binder, and the work of adhesion was used to evaluate the effect of BHET on the adhesive properties of the interface. At the same time, the energy ratio value was used to evaluate the moisture damage resistance of the asphalt mixture. The simulation result showed that BHET increased the CED of the asphalt binder because of the similar molecular structure of the two materials, and also due to the formation of some hydrogen bonds. The strongly polar BHET formed a stronger bond with granite than with asphalt and improved the adhesive performance of the interface by 29%. Moreover, moisture damage resistance of the asphalt mixture enhanced by 42% because addition of BHET resulted in the increase in the hydrophobic properties of the asphalt binder and also the bond energy between the asphalt and granite increased. Most simulation results agree well with experimental data reported in previous studies.

Automated summary

This study developed an environmentally friendly anti-stripping agent for asphalt and evaluated its improvement effect on the cohesive and adhesive properties of an asphalt mixture through molecular dynamics simulation. The simulation results showed that the anti-stripping agent increased the cohesion and adhesion of the asphalt, while also enhancing the moisture damage resistance of the asphalt mixture. Most simulation results were in agreement with experimental data reported in previous studies.