Evaluation on the diffusion-fusion properties and interfacial mechanical behavior of virgin and aged asphalt

Abstract

To investigate the regeneration mechanisms of rejuvenated asphalt mixtures, molecular simulation techniques were employed to research virgin and aged asphalt's fusion characteristics and interface mechanical properties. The blended zone was identified based on relative density distribution, and a molecular-scale calculation method for the Degree of binder Blended (DOB) between virgin and aged asphalt was proposed. Finally, the influence of DOB on the mechanical properties of the asphalt-aggregate interface was evaluated through interface pull-out tests. The results revealed that the proposed molecular-scale DOB calculation method effectively assessed the blending effectiveness between virgin and aged asphalt. Higher degrees of asphalt aging made it more challenging for aged asphalt to fuse with virgin asphalt, while elevated temperatures facilitated diffusion fusion between them. Under tensile loading, initial cracks were primarily initiated from the rejuvenated asphalt's blended zone. This region represented the weakest area within the interface system and was prone to fracture under load. The increase in DOB significantly improved the interfacial properties of recycled asphalt, with the increase in DOB the interfacial tensile strength increased by 4%–14% and the fracture energy increased by 10%–19%. However, this enhancement effect diminished with an increased degree of asphalt aging. At the molecular scale, increasing DOB improved the interface strength and deformation resistance of rejuvenated asphalt. The molecular simulation results provide theoretical guidance for evaluating the fusion degree of aged asphalt in RAP materials and determining the utilization efficiency of aged asphalt.