Research On Crack Of Interface For Asphalt Mixture Using Microstructure

In order to adapt to the mode of modern transportation development for ecological design and improve road performance, crumb rubber(CR) modified asphalt mixtures widely used in high grade road construction. With the growth of the pavement service time for CR modified asphalt mixtures, it ineluctably appears various damages. Among them, early cracking of pavement is one of the main form of road damage, the crack formation is seriously influence use pavement performance and service life. So it is important to study the crack mechanism and crack propagation law.Because of asphalt mixtures is a kind of poly phase and compound material, and it has anisotropy adhesion property. Conventional macroscopic test which based on dimension as principle can only establish macro features and road asphalt mixture performance, but the generation of crack for macroscopic test develop with microscopic structural damage. So macroscopic test can’t fundamentally to study crack generating mechanism and crack propagation law. We must from microstructure to study essence of interaction among species and behavior. The paper use DSCM and CZM numerical simulation to study crack generating mechanism and crack propagation law of CR modified asphalt mixtures from microstructure.By using DSCM and Semi-Circular Bending to test the asphalt mixture(simulate long term temperature aging and water, salt solution freeze-thaw cycle) crack initiation and the propagation rules of crack in terms of microcosmic view. The full-field displacement and strain were analyzed by Vic-3D software, we can extract the deformation field and strain field from the sample’s surface.In view of the characteristics of the complex surface for asphalt mixtures, use Digital Image Processing to manipulate images. The surface information of specimen was capture by CCD camera, grayscale transformation, histogram modification, image smoothing, image sharpening edge detection, binarization and so on by use IPP6 and R2 V,with large finite element analysis software ABAQUS to finish two-dimensional model reconstruction.For mesoscopic characteristics of aggregate and asphalt mortar contact interface,construction CZM microstructure model of CR modified asphalt mixtures. The CZM fracture parameters were got from SCM, viscoelastic parameters was got from compression creep test. The paper perform numerical simulations of pre incision CR modified asphalt mixtures CZM model. Compare crack propagation path, horizontal displacement field, vertical displacement, strain field of numerical modeling with DSCM,it can validate the reliability of numerical modeling result. Study influencing factors of interface crack though CZM model. Study main influence factors of crack expansion though stress intensity factor of different crack. Design and complete the crack propagation path prediction of CR modified asphalt mixtures by crack influencing factors.Combine with DSCM and CZM. We study crack generating mechanis and crack propagation law of CR modified asphalt mixtures from microstructure. Through horizontal strain and horizontal stress cracking in asphalt mixture of different phase in the process of evolution and deformation characteristics of a crack are analyzed; through the changing rate of horizontal displacement and horizontal strain cracking in asphalt mixture is influenced by the external environment factors for analysis; explore the influence factors of extension in the process of the crack propagation rate; for asphalt mixture without advance incision semicircle specimen to carry on the numerical simulation of finite element model of cohesion, feasibility analysis on the simulation results.