Asphalt mixture force chains morphological characteristics and bearing capacities investigation using discrete element method

Force chain morphological characteristics and bearing capacities can reflect the asphalt mixture's skeleton external loading transfer behaviour. In this study, asphalt mixture discrete element models were established by the particle flow code in two dimensions (PFC2D) software. Force chains' morphological characteristics and bearing capacities were evaluated by considering repetitive force chains (RFC). The results indicate that dense-graded asphalt concretes (AC) transfer external loading along the vertical direction, and force chains of stone mastic asphalt (SMA) and open-graded asphalt friction course (OGFC) have large expansion areas. AC-type asphalt mixtures form force chains easily with a shorter length and weak strength. Nominal maximum aggregate size (NMAS) has little influence on force chain alignment coefficient (FCAC) and force chain angle (FCA) distributions for AC, but it has stronger effects for SMA and OGFC. Whatever kinds of asphalt mixtures, with NMAS increase, the proportion of lower strength force chains will decrease gradually. The passing percentage of sieve size 2.36 mm (P2.36) needs to be limited within a certain range to ensure the asphalt mixture with the trapezoidal force chain shape for transferring the external loading better. For example, P2.36 needs to be restricted within 34% for AC16, and thresholds are 15% and 13% for SMA16 and OGFC16, respectively.