Aggregates Behavior Analysis And District Division Of Asphalt Mixture

Asphalt mixture is a three-phase composite material which consisting of aggregates,voids and asphalt mastic, it’s a typical heterogeneous, discontinuous particle propertiesmaterials. However, the existing elastic layered system theory assumes asphalt mixture ishomogeneous isotropic material, is clearly incompatible with the actual situation.Firstly, formed a continuous gradation and gap-graded asphalt rutting specimen,cutting, assembling. and then carried out cutting tests under different temperatures andloading conditions, qualitatively analyzed the behavior of internal particles in the specimenbased on the displacement contours; combined with digital image processing techniques andstatistical methods, quantitatively analyzed the law of the particles inside the specimen,according to this law, divided the rutting specimens board into homogeneous andheterogeneity district; Finally, used PFC discrete element program, simulated and analyzedtwo different graded asphalt mixture’s rutting test, further verified the homogeneous andheterogeneity district division method. The main conclusions are as follows:(1)、Under the same conditions and external loads, the region that had particleirregular motion of the gap-graded mix slightly bigger than the dense graded mix. And asthe temperature rises or load increasing, the range of irregular particles motion wasincreasing, namely the district which particles should consider particulate or non-homogeneity has increased.(2)、After compacted the asphalt mixture we can found that the spindle orientation ofaggregates focused on80-100°. The displacement of the particle beneath loading positionin the Y direction (vertical) basically downward, and angular displacement direction of theregion is evenly distributed. The range of positions on both sides of the load, the verticaldisplacement of the particles there are some negative shift (upwards), and the displacementangle is mainly concentrated in the0-50°, namely the particle’s displacement on both sidesof the loading position is mainly spread to both sides, and some particles are upwards.(3)、By using gray correlation analysis method, we know that the sensitivity of dense graded mix to temperature affection is relatively smaller than loads, and gap-graded mixes affected bythe load was stronger than the effect of temperature on them.(4)、Discrete element simulation results show that the law of transmission of forcechain and particle displacement vector is coincide with the real test, so discrete element isable to simulate the particle displacement law of real loading process in some extent.