Multi-gradient analysis of temperature self-healing of asphalt nano-cracks based on molecular simulation

In order to accurately explain the temperature self-healing mechanism of asphalt nano-cracks, the correlation of temperature self-healing of asphalt nano-cracks with different gradients was studied. Molecular dynamics (MD) on nano-gradient was used to simulate the temperature self-healing process of asphalt nano-cracks, and it was proposed that activation energy plays a key role in self-healing. The experimental results of the atomic force microscope (AFM) and scanning electron microscope (SEM) were interpreted by the asphalt molecular model. Simulation and experiment can be correlated and verified. The temperature self-healing phenomenon of asphalt nano-cracks was studied by three different resolution gradient methods, and the uniformity of different gradients was formed. The results show that the width of nano-cracks has a greater effect on self-healing than the temperature. Aging has a negative effect on the self-healing, and the self-healing of aging asphalt requires longer time and more activation energy. In addition, the shape of the wave crest in AFM is influenced by the number and shape of the voids on the asphalt model surface, and the folding in SEM is also closely related to the concave and convex changes on the asphalt model surface. Therefore, the multi-gradient explanation and unified demonstration of the self-healing mechanism of asphalt nano-cracks widths at different temperatures are carried out in this paper. The research results have certain theoretical and application value for promoting the further development of asphalt materials. (C) 2020 Elsevier Ltd. All rights reserved.