Mechanical properties analysis of asphalt nanostructures based on atomic force microscope and discrete element method

In order to further reveal the mechanical properties of asphalt nanostructures, the formation and evolution of "bee structure" were analyzed by means of discrete element method (DEM) combined with atomic force microscope (AFM). Firstly, asphalt AFM images, including virgin asphalt and aged asphalt, were obtained by AFM, and the "bee structure" characteristics were preliminarily analyzed. Secondly, the micro models of asphalt AFM images were established by using DEM, and the mechanical parameters provided by known correlation experiments were assigned to asphalt nanostructures. Finally, the mechanical simulation and analysis of the asphalt nanostructure models based on DEM were carried out to obtain the stress characteristics of "bee structures" under different stress states (tensile stress, compressive stress and shearing stress). It is found that the location of newly formed "bee structures" during asphalt aging is not random, which is related to the stress concentration of asphalt nanostructures. When the asphalt nanostructures were subjected to external forces, the "bee structure" has stronger resistance to external forces, but its overall mechanical properties depend on the "non-bee structure". The spatial characteristics of "bee structure" can be explained by the non-uniform stress at the same location of asphalt nanostructures. The research results provide a theoretical basis for the crack resistance of asphalt nanostructures, and have certain significance for the research and development of asphalt nanostructures.