Multi–scale observation of oxidative aging on the enhancement of high–temperature property of SBS–modified asphalt

• Models of modified asphalt was constructed, and the reasonableness was verified. • The morphology of modified asphalt was observed by AFM and FM. • The mechanism of aging was analyzed using molecular dynamics simulation. This study employed a molecular dynamics (MD) simulation to investigate the rheological and aging characteristics based on dynamic shear rheology experiments, fluorescence microscopy and atomic force microscopy (AFM) microstructure analysis. The simulation process considered both the functional groups and microstructure evaluation. Rutting factor, complex modulus, damping factor, recovery (R) and unrecoverable creep compliance (Jnr) were adopted to describe the rheological properties of virgin and aged SBS-modified asphalt (5 wt%). The microscopic morphology structure of the binder samples was characterized by AFM and fluorescence microscopy. The results showed that oxidative aging improved the rutting resistance and shear resistance of the modified asphalt, enhanced the elastic component in the asphalt matrix and promoted the generation of bee-like structures; however, it destroyed the polymer-rich phase network. Molecular simulations explained the above phenomena. Oxidative aging intensified the competition between asphaltenes and polymers, and the new equilibrium was not favorable for the development of polymer-rich phases.