Study on the influence of coarse aggregate morphology on the meso-mechanical properties of asphalt mixtures using discrete element method

To investigate the influence of coarse aggregate morphologies on the performance of asphalt mixture, three discrete element models with different coarse aggregate morphologies were proposed in this study. Skeleton contact characteristics, skeleton contact stress, coarse aggregate movement characteristics, interfacial stress distribution, and micro -crack development characteristics with different coarse aggregate morphologies were compared and analyzed. The results indicate that there is often 40 % - 50 % of compressive stress at the coarse aggregate contact point, 10 % - 20 % of tensile stress, and 30 % - 40 % of tensile and compressive mixed stress. Aggregate morphology has a more significant impact on the contact area than it does on the type of stress at the contact point or the number of main skeleton contact points. Contact stress, coarse aggregate movement, and crack development in the asphalt mixture are all greatly influenced by coarse aggregate morphologies. More needle-flake aggregates result in less contact stress, more coarse aggregate movement displacement, and faster asphalt mixture cracking. Shear stress makes up the majority of the micro -cracks that are caused by induced stress in asphalt mixture; tensile stress micro -cracks are quite minor, making up around 10 % of the total number of micro -cracks. In order to increase the aggregate - asphalt interface qualities and the crack resistance of the asphalt mixture, it is important to avoid using too much needle-flake coarse aggregate. The findings can provide guidance for the choice of raw materials and mix ratios for asphalt pavement design, improving the asphalt mixture ' s meso-mechanics and macroscopic road performance.