The molecular model of asphalt binder was established by means of molecular dynamics (MD). The MD model was validated with respect of density, glass transition temperature, viscosity and solubility parameters. An interface system was created by inserting a vacuum pad of 50 Å between 2 groups of asphalt binders to study the self-healing behavior of the asphalt binder, e.g. internal volume, diffusion rate of each component and energy variation of the model. The molecular diffusion of aged asphalt binder, SBS modified asphalt binder, and virgin asphalt binder are studied. The results show that the “compression” of asphalt binder volume and the “stretching” of the asphalt binder molecules is responsible for the disappearance of vacuum micro-cracks inside the asphalt binder. When the model volume is “compressed”, the volume of the asphalt model decreases until the micro-cracks in the asphalt binder disappear completely. The molecular volume of asphalt decreases greatly at the beginning of the MD simulation, and then becomes stable. The length of asphalt model increases in the OZ direction, while the length of the OX and OY directions decreases, indicating that asphalt “stretces” during the self-healing process. During the self-healing process, the diffusion coefficient of asphaltene molecule is the lowest, while the diffusion coefficient of the saturates is the highest at 360 K, aromatics and resins are close to the average value 6.227 × 10 −4 cm 2/s in the MD model. Self-healing is mainly based on the Van der Waals forces between non-bonded molecules. The aging of asphalt molecules reduces the diffusion rate of the asphalt model, and the SBS additive indirectly enhances the diffusion rate of asphalt.
|Journal||Construction and Building Materials|
|Publication status||Published - 10 Sept 2020|
Bibliographical noteFunding Information:
This work was supported by Inter-governmental S&T Cooperation Project of China-Poland ( 37-13 ), Inter-governmental S&T Cooperation Project of China-Czech Republic ( 43-9, 8JCH1002 ), Fund from Key Laboratory of Highway Engineering in Special Region of Ministry of Education ( 300102218508 ), Fund from Key Laboratory of Special Environment Road Engineering of Hunan Province ( kfj170501 ), National Natural Science Foundation of China ( 51611130189 , 51978547 ).
© 2020 Elsevier Ltd
- Diffusion coefficient
- Molecular dynamics simulation
- Self-healing behavior
ASJC Scopus subject areas
- Civil and Structural Engineering
- Building and Construction
- Materials Science(all)