Molecular dynamics simulation on bulk bitumen systems and its potential connections to macroscale performance: Review and discussion

Molecular dynamics (MD) simulation plays an effective role in predicting the critical properties and explaining the macroscale phenomenon at the nanoscale. This review summarized the application cases of MD simulations in various bitumen systems, considering aging, modification, and rejuvenation factors. Meanwhile, the potential relationships between the nanoscale parameters predicted from MD simulations and macroscale properties measured from experimental tests were discussed for the first time. Different molecular models of virgin bitumen, commonly-used Forcefields, and validation parameters for MD simulations on bituminous materials were summarized. Based on the reactive MD simulation outputs, the oxidative aging reaction path at the atomic scale of bitumen molecules was reviewed. Furthermore, the influence of aging (short-term and long-term), modification (polymers, fillers, and bio-bitumen), and rejuvenation (various rejuvenators) on the molecular-scale properties of virgin bitumen models would be evaluated through MD simulations. This review could help us further explore the main functions of MD simulations in different bulk bitumen systems and build an integral multi-scale research method from the molecular design and performance prediction to material optimization and synthesis of bituminous materials without lots of experimental attempts.