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. 2025 Jul 24;18(15):3472.
doi: 10.3390/ma18153472.

Molecular Dynamics Insights into Bio-Oil-Enhanced Self-Healing of Aged Asphalt

Liuxiao Chen  1   2 , Silu Tan  2 , Mingyang Deng  2 , Hao Xiang  1   3 , Jiaxing Huang  4 , Zhaoyi He  3 , Lin Kong  5
Affiliations

Molecular Dynamics Insights into Bio-Oil-Enhanced Self-Healing of Aged Asphalt

Liuxiao Chen et al. Materials (Basel). .

Abstract

Long-term aging deteriorates asphalt's self-healing capacity, yet the molecular mechanisms of bio-oil rejuvenation remain unclear. The fluidity and healing index of an asphalt binder were tested using a dynamic shear rheometer, and a healing model was established using molecular dynamics software to analyze the movement state. The results show that after adding the bio-oil, the healing index of aged asphalt increases significantly, lowering the optimal healing temperature by 10.1 °C. MD simulations demonstrate that bio-oil weakens van der Waals forces (with a 15.3% reduction in non-bonded energy) to enhance molecular diffusion, with a critical healing distance of 0.87 Å and aggregation at 1.11 Å. The bio-oil reduces the activation energy for healing from 4.97 kJ/mol (aged asphalt) to 3.75 kJ/mol. Molecular dynamics simulations can effectively aid scholars in understanding the asphalt healing process and movement patterns.

Keywords: bio-oil-recycled asphalt; mean square displacement; molecular diffusion; molecular structure; self-healing.

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Conflict of interest statement

Author Jiaxing Huang was employed by the company Survey and Design Company of Sichuan Road & Bridge (Group) Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Molecular structures of asphalt components.
Figure 2
Figure 2
Asphalt healing model with initial crack.
Figure 3
Figure 3
Composite viscosity of asphalt at different temperatures.
Figure 4
Figure 4
Flow behavior index of different asphalts.
Figure 5
Figure 5
Healing index of asphalts at different temperatures.
Figure 6
Figure 6
Density of asphalt molecular models at different temperatures.
Figure 7
Figure 7
Specific volume of asphalt molecular models.
Figure 8
Figure 8
Radial distribution function of asphalt healing models.
Figure 9
Figure 9
Cell size of asphalt healing models.
Figure 10
Figure 10
Density of asphalt healing model.
Figure 11
Figure 11
Energy distribution of asphalt healing models.
Figure 12
Figure 12
Mean square displacement during asphalt model healing.
Figure 13
Figure 13
Diffusion coefficient of asphalt molecules at different temperatures.
Figure 14
Figure 14
Relationship between ln (D) and 1/T.
See this image and copyright information in PMC

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