Asphalt mixture skeleton main force chains composition criteria and characteristics evaluation based on discrete element methods

• Skeleton structure is the main body to transfer external loading in asphalt mixtures. • External loading was transferred effectively via main force chains for asphalt mixture skeleton. • Under external loading, AC type asphalt mixtures are easier to form III type force chains compared with others. To overcome the deficiency of existing force chains identification criteria for evaluating asphalt mixture skeleton structure, a new force chains identification criteria and skeleton main force chains ( MFC ) are proposed and investigated in this study. Firstly, discrete element method (DEM) models of different asphalt mixtures were established to conduct virtual bearing plate tests. And then, asphalt mixture MFC morphological characteristics were analyzed. Relevant results indicate that although dense-graded asphalt concrete (AC) has more number force chains, stone mastic asphalt (SMA) and open-graded asphalt friction course (OGFC) have higher MFC number proportions. Under external loading, AC is easier to form III type force chains. SMA and OGFC have longer length MFC in terms of a single MFC . MFC of SMA is closer to linear compared with AC. This is beneficial to hold stability and transfer external loading for MFC. OGFC has the relatively worst quasi-linearity. Under thinner pavement structural thickness, SMA has a small external loading extension area compared with AC type asphalt mixture which is beneficial to improve external loading transferring efficiency.