The Research On Meso-Structure Of Large Particle Porous Asphalt Mixture Material Crack Propagation

Asphalt mixture is the multiphase material with the mainly formed by aggregate, asphalt mortar and void. Its micro structure has close connection with its macro-performance.The large particle porous asphalt mixture material has excellent performance of crack resistance. Models were generated by digital image processing technique, CT scan, Matlab image processing software and Abaqus software. The author obtained the section information of large particle porous asphalt mixture material through CT scan and extracted three parts of the large particle porous asphalt by programming system, which can realize the enhancement, segmentation and vector quantization of image. The models of2D reconstruction were finally made with Abaqus software of finite element analysis.Due to different properties of aggregate and asphalt mortar, the author set up to virtual tensile test with asphalt samples. Compare with2D models in stress, strain and displacement, the thesis discussed the influence of clearance on the split test of asphalt mixture material, the influence of modulus of asphalt mixture on split crack of asphalt. The study reveals that large particle porous asphalt mixture material showed great nonhomogeneity in ess-strain, which highlights the importance of mechanical property on aggregate and clearance in the asphalt mixture material.The author used extended finite element method (XFEM) to imitate the influence of aggregate and void on crack propagation and presented that extended rules of mixed mode crack in homogeneous small beams and that influenced by aggregate and by void. The research found that both aggregate and clearance can "attract" cracks, which can change the propagation paths of crack and delay the crack. Based on the numerical simulation method, the author found that the large particle porous asphalt mixture material has superior performance in preventing the reflection crack of propagation.