| Coarse aggregate abrasion value, based on Los Angeles abrasion test, is one of the most important mechanical indicators of road construction materials design. The factors that affect abrasion loss are analyzed by using the discrete element method, to simulate this progress. Based on energy tracking method, a computer program of discrete spheres’movement procedure is redeveloped on the platform of3D particle flow code (PFC3D). To determine the stress state of the aggregates, the further analysis is completed by tracking the unit body’s energy within a specify time step, which discussed the experiment condition and the aggregate micro properties. Sever subjects were studied in this dissertation as follows:Firstly, the mechanism of energy transfer were analyzed between crushing process and wear loss in the Los Angeles abrasion test, which explaining the objective evaluation of the simulation test is energy transfer, and verifying the interaction force and friction of aggregate has a significant impact on wear loss. The results show that the mechanism of abrasion loss is mainly from the steel balls and the aggregate particles’collide, rolling and trace wear.Secondly, virtual test model was build with Los Angeles abrasion tester by using the PFC3D software. By tracking the energy change of aggregate unit during the process, the method of energy transfer has been analyzed between aggregate and aggregate, aggregate and steel ball. This paper presents the realization method of wear energy redistribution in numerical simulation, that is, distributing peak energy according to the specified level, it also associated with particles’ size and velocity, which provides a feasible path to the virtual test.Thirdly, the fragmentation process of aggregate particles has been analyzed by impacting test. Changes in the percentage of crushed stone chips as index to assess the content of reducing the amount of primary particle volume, and then, obtained the relationship by calculating between impact energy and volume change rate of the primary particles, so as to realize the virtual implementation process of coarse aggregate abrasion.Finally, In view of the number of steel balls, the strength and stiffness of coarse aggregate, typical aggregates used in asphalt mixture was analyzed by numerical simulation. The process was compared to Los Angeles entity test, and the results showed that:(1) In the Los Angeles abrasion test, steel ball is worn tool to aggregate that effect of the implementation, but also is the abrasion energy transfer medium body, which play a crucial role in the aggregate abrasion. In the steel ball function, aggregate abrasion loss caused by impact, shear failure of material is more man6times larger than the pure wear loss in numerical value.(2) Particle contact stiffness reflects the strength of the material, which has a great effect on the aggregate abrasion loss degree, with the particle contact stiffness increases, the macro material abrasion resistance performance increases, and the ability of anti-impact and anti-friction are increased. Compared with entity test, the study found that, basalt had a higher strength, and its wear loss was significantly less than pebble’s, which confirms the reasonableness of simulation results.(3) The phenomena of wear and breakage coexist in coarse aggregate Los Angeles abrasion test, and breakage been a main role. The more surface texture rougher, The better wear resistance in coarse aggregate. |
