Numerical Simulation Of Asphalt Concrete Specimen Cracking Process Based On The Microscopic Material Interface Features

Various kinds of damage appeared in using process of asphalt pavements, and the crack has been one of the main problems during the use of asphalt pavements in all countries of the world. Currently, the cracking research of asphalt pavement is mostly carried out by means of experimental methods, but in view of the special nature of the asphalt concrete material, it is time-consuming and difficult to achieve the desired effect by means of a large-scale experimental study. Therefore, it is necessary to establish a means of numerical methods of asphalt concrete meso-fracture model to study the fracture behavior of asphalt concrete.In this paper, starting from the microscopic scale, crack initiation and propagation mechanism of asphalt pavements at low temperature is carried out with cohesive zone model (CZM). This study will help optimize the design of asphalt pavement. The study have important theoretical and practical value for asphalt materials and asphalt layer structure, and also have a certain significance for road maintenance and conservation.Firstly, taking into account of two-dimensional digital specimens, the study propose a method of determining the particle size of coarse aggregate number, a method of coarse aggregate generating irregular shape, an aggregate random delivery algorithm and specimen a dimensional digital visualization algorithm. These methods can characterize the asphalt concrete aggregate gradation, aggregate content, aggregate size, aggregate spatial distribution, the gap size, porosity size, void distribution and other characteristics. Taking into account of three-dimensional digital specimens, the aggregate is regarded as spherical particles in order to simplify consideration in this paper. The study propose a method of determining the particle size of coarse aggregate number, an aggregate random delivery algorithm and a algorithm of distinguishing aggregates and asphalt mortar. The study introduce the concepts and basic theory cohesion model and select bilinear cohesive force model which is suitable for asphalt concrete material. The study describe the two-dimensional zero thickness cohesion unit embedding algorithm and three-dimensional zero thickness cohesion unit embedding algorithms.Secondly, the study test the cohesion of the model parameters, using composite specimens to measure the bond strength and the fracture energy of asphalt mortar-aggregate interface and using asphalt mortar specimens to measure the bond strength and the fracture energy of asphalt mortar-asphalt mortar interface. Based on the validation of the test material, the paper calculate the grading and Whetstone ratio of asphalt mortar. By the three-point bending beam test and the indirect tensile test, the study identify the fracture energy (80.82J/m2 for asphalt mortar-aggregate interface and 326.91J/m2 for asphalt mortar-asphalt mortar interface) and the bond strength (2.87MPa for asphalt mortar-aggregate interface and 4.33Mpa for asphalt mortar-asphalt mortar interface).Thirdly, based on the three-point bending beam test of asphalt concrete, the study obtain and process the digital image of the specimen, then import ABAQUS software for modeling. With the two-dimensional zero thickness unit cohesion embedding program, two kinds of zero thickness cohesion unit are embedded in the model for the asphalt mortar-aggregate interface and the asphalt mortar-asphalt mortar interface. Then the model is submitted to ABAQUS software to calculate. Based on the load-displacement response and the energy consumption-displacement response, the study compare and analysis the difference between the test results and the numerical simulation results. The study demonstrate the applicability of the numerical simulation results and analyze The fracture process of the numerical simulation.Then, based on the two-dimensional meso-fracture model and the virtual fracture test, the paper study some factor’s influence on the low-temperature fracture properties of asphalt concrete. These factor include the aggregate properties (aggregate gradation, fraction, the maximum particle size, spatial distribution, flat-ratio, long axis angle, angularity and the parameters of the asphalt mortar-aggregate interface),asphalt mortar properties (the parameters of the asphalt mortar-asphalt mortar interface) and void properties (void percentage, size and spatial distribution). It concrete has conducted a comprehensive analysis of parametric sensitivity for AC-16 asphalt.Finally, the study crete a three-dimensional meso-fracture model and compare the simulation results of the three-dimensional meso-fracture model and the two dimensional meso-fracture model. The paper study some microparameter’s influence on the low-temperature fracture properties of asphalt concrete.