Study on compatibility mechanism of plasticizer and asphalt based on molecular dynamics

This work aims to reveal the compatibility mechanism of different plasticizers with the base asphalt using molecular dynamics (MD) simulation. For this purpose, four kinds of plasticizers were chosen, namely dioctyl phthalate (DOP), dioctyl adipate (DOA), acetyl tributyl citrate (ATBC), and trioctyl trimellitate (TOTM). The compatibility between those plasticizers and the asphalt was evaluated by various MD simulation parameters, including electric dipole moment, solubility parameters, and binding energy, and the simulation results were verified using macroscopic tests. The results show that the four plasticizers are effectively miscible with asphalt within the temperature range of 130 degrees C to 170 degrees C. The optimal temperatures for DOP, DOA, ATBC, and TOTM in modified asphalt preparation are 140 degrees C, 130 degrees C, 140 degrees C, and 150 degrees C respectively. The saturate component is more miscible with weak polar plasticizers, while the other three asphalt components are more miscible with strong polar plasticizers. TOTM has the best stability in combination with asphalt and ATBC has the worst. Aromatics and saturates have better torsional and bending deformation ability, and are more likely to form stable blending systems with strong polar