Different proportions of bio-oil (5, 10, 15, and 20 wt%) were added into aged asphalt for its regeneration. Molecular dynamic simulations were used to measure the thermal and mechanical performances of bio-oil regenerated aged asphalt (BRAA). A new, simplified BRAA model was built to calculate the specific heat capacity, thermal expansion coefficient, elastic constant, shear modulus, bulk modulus, and Young's modulus. Simulation results showed that the thermal expansion coefficient (CTE α) of asphalt at 298 K decreased by 10% after aging. Bio-oil of 5 wt% could make the CTE α restore to the original level of base asphalt, while the addition of bio-oil would further decrease the specific heat capacity of aged asphalt. The shear modulus (G), Young's modulus (K) and bulk modulus (E) of asphalt increased after aging and decreased with the increasing amount of bio-oil. According to the calculated E/G value, the ductility of aged asphalt increased by 6.0% with the addition of 10 wt% bio-oil, while over 15 wt% bio-oil would make the ductility of BRAA decrease. In summary, the regeneration effects of bio-oil to the thermal expansion coefficient, flexibility, and ductility of aged asphalt had been proven, while excessive bio-oil would decrease the thermal stability of asphalt.
Keywords: aged asphalt; bio-oil; molecular dynamic simulation; regeneration; thermal–mechanical properties.