Research On High Temperature Performance Of Asphalt Mixture Using Discrete Element Method

Rutting, corrugation, shoving and other diseases may appear on the surface of asphalt pavement due to the lack of asphalt mixture’s high temperature performance. Rutting has a negative effect on pavement planeness, which also reduces skid resistance and even affects driving comfort and safety. Because of nonuniform and complex material, the method of traditional laboratory test requires not only a lot of time and cost, but also has difficulties finishing relevant repeatability and reproducibility studies. Discrete Element Method can be used for auxiliary analysis of high temperature performance of asphalt mixture. And it is important to improve pavement performance. In this paper, Discrete Element Method about high temperature performance of asphalt mixture was analyzed:Firstly, asphalt mixture was divided into coarse aggregate, asphalt mortar and gap. The asphalt mixture discrete element model was built according to the different component.Secondly, after completing laboratory test, macro parameters were obtained, and then microscopic parameters were calculated by conversion formula. Then the result of virtual test was compared with the result of laboratory test.Again, virtual uniaxial creep test was introduced to study creep when varying gradation and asphalt-aggregate ratio. Correlation of different factors to high temperature performance was obtained. Asphalt content was the most important factor influencing high temperature performance of asphalt mixture, followed by aggregate with diameter from 4.75mm to 9.5mm, then followed by aggregate with diameter from 9.5mm to 13.2mm.Finally, with constant contact parameters of asphalt mortar, the content of aggregate diameter greater than 2.36mm were changed. After that the results of virtual experiment were analyzed, and different micro-parameters such as contact force, velocity, displacement were studied. For asphalt mixture, a more uniform contact force inside the mortar, between the mortar and the aggregate, a smaller mean force between the coarse aggregate, and a smaller vertical displacement and displacement angle of the coarse aggregate, and a smaller strain rate of the test pieces, a smaller the translational and rotational speed of the coarse aggregate behaved a better high temperature performance. It was also studied that aggregate reached peak speed more quickly under the direction of the load. In addition, the coarse aggregate had a smaller vertical displacement, a bigger horizontal displacement and rotation angle when the diameter decreased.It was suggested in the paper that the content of aggregate with diameter from 4.75 mm to 9.5mm,9.5mm to 13.2mm should be more than 20% and 15% separately when design gradation. The passing rate of aggregate with diameter of 4.75mm should be less than 45%, and the content of aggregate with diameter from 4.75mm to 9.5mm should be more than 15%.