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

[Display omitted] • The strong polar plasticizers have poor inter-solubility with the saturates and good inter-solubility with the other three components of asphalt. • The ranking of the compatibility between plasticizers and asphalt obtained by simulation and experiment, from best to worst, is trioctyl trimellitate, dioctyl adipate, dioctyl phthalate, and acetyl tributyl citrate. • Molecular polarity and spatial configuration are important factors affecting the binding stability of plasticizers and asphalt's four components. • The selection of plasticizer schould be based on the proportion of the four components in asphalt during engineering applications. 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 °C to 170 °C. The optimal temperatures for DOP, DOA, ATBC, and TOTM in modified asphalt preparation are 140 °C, 130 °C, 140 °C, and 150 °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 plasticizers. Asphaltenes and resins have more stable benzene ring structures, they have greater binding energy with DOA, which is chain-variable and weakly polarized. [ABSTRACT FROM AUTHOR]