Use of molecular dynamics to investigate self-healing mechanisms in asphalt binders

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The fatigue-cracking life of an asphalt mixture measured in the laboratory is generally a small fraction of the fatigue-cracking life observed in the field. One of the reasons for this large difference is the self-healing property of asphalt binders. Self-healing is a process that reverses the growth of fatigue cracks during rest periods between load applications. A thorough understanding of the healing mechanism is required to accurately model and predict the influence of healing on the fatigue-cracking life of asphalt mixtures. Previous studies have used experimental evidence to demonstrate a correlation between chemistry of asphalt functional groups, such as chain length and branching, and healing measured in asphalt binders. One of the mechanisms of healing is the self-diffusion of molecules across the crack interface. This paper demonstrates the use of molecular simulation techniques to investigate the correlation of chain length and chain branching to self-diffusivity of binder molecules. The findings reported in this paper are consistent with observations reported in previous studies and expand on the understanding of the relationship between molecular architecture, self-diffusivity, and self-healing properties of asphalt binders. © 2011 American Society of Civil Engineers.

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Journal of Materials in Civil Engineering