Study On Asphalt Mixture Compaction Characteristics In Vacuum Based On Discrete Element Method

Because of smooth, low noise, simple maintenance and driving comfort etc, asphalt pavement is the first choice for road construction around the road. Compaction can increase the strength of the pavement materials, reduce the pavement deformation produced by the traffic load, improve the supporting capacity and stability of asphalt pavement as the end of procedure. If the compaction degree of asphalt pavement increases by 1%, its supporting capacity can increase by 10%~15%, and the cost of compaction accounts just for 1%~4% of total budget of construction. Therefore, improving the strength and supporting capacity of the pavement from the aspects of compaction in road construction is very economic and effective. But roller drum contact ground pressure should not be more than material’s ultimate strength, generally for 0.8~0.9 times of ultimate strength. So just relying on improving the mass of roller or linear pressure to improve the compaction effect is limited.In order to improving the compaction degree and quality, the formation process and composition characteristics of asphalt mixture were analyzed in theory, and put forward vacuum compaction, a new method of compaction aimed at gas phase structure.First, the micromechanics model of asphalt and the principle of vacuum compaction were expounded and analyzed, then the conceptual model of void was given from microscopic. The relationship between void content and bulk modulus was deduced, and pinpointed that void content can influence compatibility and pavement performance of asphalt mixture through theoretical analysis.Then, making the improved Marshall compactor can be realized for compacting asphalt mixture in vacuum environment. Simulate asphalt mixture compaction test in no vacuum, and the degree of vacuum was-0.04,-0.06,-0.08,-0.09 MP environment with using AC13 gradation of mixture and vacuum compaction mould, measure the settlement after every compaction and accumulated settlement under different status. It was concluded that vacuum compaction can increase compaction efficiency, improve compaction effect, and compaction effect will be more better with the increase of vacuum degree.Finally, compaction characteristics’ analyses and influencing factors’ measurement were limited in view of vacuum compaction test, so generated a certain number of particles to simulate aggregate, asphalt mortar and pore gas to establish an asphalt mixture discrete element model to simulate vacuum compaction with using PFC3 D software. A corresponding relationship with vacuum compaction test was established to analyze asphalt mixture compaction characteristics and influencing factors.