Large-scale molecular dynamics simulation and aggregate behavior research on asphalt

Case Studies in Construction Materials, vol. 21, pp. e03749

Abstract

In this comprehensive study, a molecular dynamics (MD) model consisting of approximately 150,000 atoms was developed within the Strategic Highway Research Program (SHRP) framework to investigate the behavior of AAA asphalt, focusing on asphaltene aggregate dynamics behavior over a simulation time span of 0.282 microseconds. The findings reveal that the model achieves a stable state in terms of both energy and microstructure without significant changes or the formation of densely clustered molecules, despite the extensive simulation period. Notably, the patterns of asphaltene aggregation were found to significantly influence the MD system energy, with variations ranging from loosely organized structures due to dispersed asphaltenes to more structured, energy-efficient clusters formed by encapsulated asphaltene pentamers. The size of asphaltene aggregates emerged as a pivotal factor, affecting their encapsulation and leading to distinct formation patterns. Furthermore, the research highlighted that increasing shear rates prompt the depolymerization of asphaltene aggregates, shifting from large-scale structures to smaller ones and adapting dynamically to the flow conditions by aligning parallel to the shear direction. This study underscores the critical impact of asphaltene aggregate behavior and shear rates on the structural integrity and distribution within the asphalt model, offering profound insights into the MD of asphalt materials. • The asphalt MD model stops forming new clusters after a brief stabilization period, even with more simulation time. • Asphaltene aggregate size affects asphlat's structure and energy, shaping its organization from dispersed to clustered forms. • Shear rates greatly impact asphaltene integrity, causing depolymerization and changes in orientation.

Authors 3

1. Jiegui Du
   Affiliation as printed

   Yizhao Expressway Project Headquarters, Zhaotong City 657000, China

2. Chaoliang Fu corresponding Aachen Institute of Highway Engineering

   RWTH Aachen University

   Affiliation as printed

   Institute of Highway Engineering, RWTH Aachen University, Aachen 52074, Germany

3. Guannan Li corresponding

   Harbin Institute of Technology · Chongqing Jiaotong University · Changsha University of Science and Technology

   Affiliation as printed

   National Engineering Research Center of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha, Hunan 410114, China

   School of Traffic and Transportation, Chongqing Jiaotong University, Chongqing 400074, China

   School of Transportation Science and Engineering, Harbin Institute of Technology, Harbin 150090, China