Analysis of Fracture Failure Mechanism of Asphalt Mixture Based on the Discrete Element Method

In order to investigate fracture failure mechanism of asphalt mixture from micro-structure,probability method has been used to present a theoretical formula which develops to convert the aggregate weight gradation into the two-dimension (2D) quantity gradation.Two 2D digital specimens with different thicknesses of asphalt films are generated based on particle generation algorithm.Based on the discrete element method,the fracture process of asphalt mixture beam has been simulated and the effect of asphalt film thickness,cohesive strength of asphalt mastics and adhesive strength between asphalt mastic and aggregate on the fracture failure of asphalt mixture has been also investigated.The results show that the cracking has the tendency to occur in asphalt mastics for asphalt mixture with thick asphalt films and the cohesive strength of asphalt mastics has a great influence on fracture failure of this type mixture.For asphalt mixture with thin films,the early cracking often appears in asphalt mastics and propagation of cracking occurs at the interface between aggregates and mastics.Fracture initiation is dominated by the cohesive strength of asphalt mastics and propagation of cracking is controlled by adhesive strength between asphalt mastic and aggregate for mixture with thin films.