Research On Creep Shear Microscopic Property Of Asphalt Mixture Based On Digital Image Processing

Currently, Asphalt Mixtures lack of shear resistance and generates a great deal of shear stress in the asphalt layer heavy traffic, making the asphalt pavement damage by buckling ruts or load-type cracks and so on. So this article using digital image processing technology to research Creep Shear and microscopic mechanism destroy of Asphalt Mixtures under the indoor loading conditions. Using digital image processing technology to analysis the changes of porosity?CT number?damage variable at different graded and levels before or after destroyed inside mixes, then make fractal analysis. Also examines the trajectory before or after destroyed of the inside coarse particles, later using finite element software to validate the applicability of use digital image to make the numerical simulation.Using digital image processing technology binary the CT images before and after the SPT shear creep test destroyed, calculated the porosity, shear failure of the specimen occurred in the initial void that densely distribution. The initial CT number presentation the rule of "two large, intermediate small" at all levels with the specimen, The corresponding to distribution of Void ratio. The CT number is proportional to the density, the shear failure specimens of middle layer CT the number of larger void ratio decreased more significantly. The CT number decreased more significantly in the specimens middle layer which have larger void ratio after the Shear failure. The damage variable maximum value appeared in the middle specimens which porosity of is relatively large, that shear failure is more serious, the damage variable of gradation of AC-13 was higher than that SMA-13, so the SMA-13 graded Creep Shear performance is stronger. Before and after the Creep Shear failure of the Asphalt mixture has the characteristic of fractal.Analysis of the trajectory of coarse particles before and after damage, the mean values and the discrete of translational displacement of particle before and after the test distribution AC-13 is greater than SMA-13, the specimens have the larger displacement in the middle layer of the two graded; The overall mean value and standard deviation of translational displacement angle that is graded AC-13 greater than SMA-13. The changes of rotation trajectory also called spindle orientation after shear failure, the fluctuation of axis direction that gradation of AC-13 slightly bigger than SMA-13; The unity of particle axis direction is the graded AC-13 larger than SMA-13, SMA-13 has more particles tend to be arranged horizontally; The main direction of the difference between before and after damage the middle layer slightly larger than other layer, failure is uneven. Also verified the performance of fatigue shear that graded SMA-13 is greater than AC-13.Through the ABAQUS numerical simulation of split test, found that stress distribution are relatively regular of homogeneous two-dimensional specimen, distribution is very uneven of the stress parameters that with the help of 2D digital image processing technology to reconstruct the non mean sample splitting test, This consistent with the actual splitting test stress condition of mixture. Concentration factor can well reflect the mechanical properties of asphalt mixture, in order to verify the applicability of DIP-FEM method.