Discrete Element Simulation of Asphalt Pavement Milling Process to Improve the Utilization of Milled Old Mixture

In order to improve the utilization of milling materials, save stone resources and reduce milling energy consumption, the aged Styrene-butadiene-styrene (SBS) modified asphalt was used as a binder to prepare AC-16 asphalt mixture to simulate old asphalt pavement materials. First, the test and discrete element simulation results of uniaxial compression tests were used to calibrate the parameters of the parallel bonding contact model between asphalt mortar and aggregates. On this basis, a microscopic model of the asphalt mixture was established to simulate the old asphalt pavement. Then, the discrete element software PFC (Particle Flow Code) was used to simulate the milling process of the old asphalt pavement. Analyzed the force of the cutting tool and the utilization rate of milling materials, and the optimal milling speed and milling depth were determined. Finally, the energy consumption in the milling process was measured. It is concluded that in the process of milling the old asphalt pavement, using a cutting angle of 42 degrees, milling speed of 0.5 m/s and milling depth of 20 mm can reduce the wear of the cutting tool. In this case, the direct utilization rate of milling materials is 85.3%, and the rate of energy consumption reduction is 33.53%. After parameter optimization, the utilization rate of milling materials can be increased by 17.4%.