Molecular Dynamics Insights into Bio-Oil-Enhanced Self-Healing of Aged Asphalt

Abstract

Long-term aging deteriorates asphalt's self-healing capacity, yet the molecular mechanisms of bio-oil rejuvenation remain unclear. The fluidity and healing index of an asphalt binder were tested using a dynamic shear rheometer, and a healing model was established using molecular dynamics software to analyze the movement state. The results show that after adding the bio-oil, the healing index of aged asphalt increases significantly, lowering the optimal healing temperature by 10.1 °C. MD simulations demonstrate that bio-oil weakens van der Waals forces (with a 15.3% reduction in non-bonded energy) to enhance molecular diffusion, with a critical healing distance of 0.87 Å and aggregation at 1.11 Å. The bio-oil reduces the activation energy for healing from 4.97 kJ/mol (aged asphalt) to 3.75 kJ/mol. Molecular dynamics simulations can effectively aid scholars in understanding the asphalt healing process and movement patterns.

Keywords: bio-oil-recycled asphalt; mean square displacement; molecular diffusion; molecular structure; self-healing.