Composition optimization and diffusion behavior of a cold rejuvenator in aged asphalt using molecular dynamics

To address the challenges of low utilization efficiency and weak adhesion in the cold recycling of reclaimed asphalt pavement, this study developed a novel cold recycling rejuvenator (CRR) designed for ambient temperatures. Guided by molecular dynamics (MD) simulations, the research screened penetrants using asphalt dissolution tests and determined the optimal CRR dosage and regeneration time via dynamic shear rheometry. Diffusion mechanisms were analyzed through MD-derived metrics, including diffusion coefficients and interaction energies, and further validated using fluorescence microscopy. Results indicate that CRR composition and dosage significantly impact diffusion behavior at 25 ℃, with limonene playing a dominant role in the process. Specifically, the RA3 formulation achieved optimal diffusion at a 12% dosage. The CRR effectively reduced interactions between asphaltene molecules, which enhanced molecular dispersion and partially restored the asphalt’s colloidal structure. Notably, after only 10 min of rejuvenation, the aged asphalt recovered 96% of the performance of virgin asphalt.