Enhancing durability of reclaimed asphalt through interface diffusion optimization: Experimental and molecular dynamics

The diffusion behavior between aged asphalt and rejuvenators is critical for designing effective pavement recycling strategies. This study investigated the diffusion behavior of three rejuvenators using experimental and molecular dynamics (MD) simulations. The interaction performance was assessed by wetting, anti-aging, and self-healing analysis. The micro-interface diffusion was characterized by optical parameters, while MD simulations illuminated the underlying mechanism. Comprehensive behavior was evaluated by a weighted sum model (WSM). Results showed that Industrial vegetable oil (IV) achieved a superior comprehensive performance with the strongest interfacial energy (increased at least by 28 %), attributed to polar bonds between its carboxyl groups and oxidized asphalt. Refined waste engine oil (RW) exhibited the highest diffusion coefficient indicating rapid diffusion, while Naphthenic oil (NO) showed slower diffusion and weaker integration (50 % difference). Increased time and elevated temperature (from 25 °C to 70 °C) significantly enhanced diffusion, with IV achieving the most uniform morphology at high temperatures. The WSM score ranked the overall performance as IV (0.82) > RW (0.75) > NO (0.58). MD-derived diffusion coefficients aligned with experimental data, providing multi-scale insights for rational rejuvenators selection in asphalt recycling. • Multi-criteria evaluation of rejuvenator effectiveness through wettability, anti-aging, self-healing, interface diffusion assessments. • Image-based diffusion process enabling quantitative monitoring of diffusion homogeneity across asphalt interfaces. • Molecular dynamics-driven analysis identifying polar-aromatic interactions and bio-oil components as critical diffusion accelerators. • A multi-scale experimental and simulation approach provides integrated insights for rejuvenator evaluation.