Development of tall oil compound rejuvenator: a molecular dynamics and quantum chemistry approach

This study investigates the aging mechanism of asphalt and proposes a molecular simulation-based method for designing compound rejuvenators. Quantum chemistry (QC) was employed to select rejuvenator components by comparing molecular surface electrostatic potential (ESP), polarity, orbital energy gap, and bond dissociation energy (BDE). Molecular dynamics (MD) simulations were used to determine the optimal component ratio of the compound rejuvenator by evaluating viscosity, diffusion ability, compatibility, and disaggregation ability, followed by experimental validation. The results show that the introduction of oxygen-containing functional groups after asphalt aging leads to charge concentration and increased polarity in asphalt molecules, resulting in large-scale aggregation. Among the asphalt components, asphaltenes exhibit the highest reactivity, with aging reactions mainly occurring on benzene rings and adjacent regions. Aged asphalt molecules display reduced chemical stability. Tall oil fatty acids (TOFA) demonstrate excellent disaggregation ability, significantly reducing viscosity and improving the rheological properties of aged asphalt. Aromatic oil shares a similar molecular structure and chemical properties with asphalt, ensuring good compatibility of the compound rejuvenator. Lignin has high reactivity and can act as a sacrificial agent against chemical attacks, thereby slowing down the aging process. When the ratio of tall oil fatty acids, aromatic oil, and lignin is 1:2:1 (1Z2F1M), the compound rejuvenator achieves the best overall rejuvenation performance.