Experimental Research On Numerically Implemented Three-dimensional Viscoelastic Constitutive Model Of Asphalt Mastic

Asphalt mixture consisting of particulate composites has a very complex internal structure, which is mainly composed of aggregates, asphalt binder materials and voids. Fine aggregate as a dispersed phase dispersed in the asphalt mortar medium forms fine dispersion,which is called asphalt mastic in this paper. Combined with computer finite element simulation and laboratory test methods to explore the predictive power and precision of three-dimensional viscoelastic constitutive model of asphalt mastic for its viscoelastic mechanical property,we can lay the research foundation for asphalt mixture meso-mechanical behavior and the performance of asphalt pavement road.Firstly, we derived both creep type and relaxation type of three-dimensional linear viscoelastic constitutive equations for asphalt mastic and its incremental form of expression,and then numerically implemented the constitutive model for asphalt mastic by using Fortran language to compile UMAT subroutine.In order to receive the model parameters,the aggregate gradation and material usage of the asphalt mastic with maximum nominal diameter of 1.18 mm were designed based on Aggregate gradation and best Whetstone ratio of AC-20 asphalt mixture. Through the results of uniaxial tensile creep and torsional shear creep test for asphalt mastic by using Kyle M-100 measurement and control electromagnetic dynamic mechanical test system under 20 ℃,we obtained tensile creep compliance and shear creep compliance parameters with correction generalized Kelvin model By using fitting tool Origin. Then the parameters of relaxation modulus can be calculated through Laplace transform and Matlab program.Finally,the numerical simulation and experimental validation of uniaxial compression and three-point bending test through three different load patterns under different load paths were Implemented,and the comparative analysis of the results proved the applicability of the asphalt mastic three-dimensional linear viscoelastic constitutive numerical model in this paper. Within the range of allowable error,the model can describe the mechanical behavior of asphalt mastic. Therefore,the finite element numerical simulation method can be used for reasonable forecast on the mechanical response behavior of asphalt mastic in the practical application,which has important practical significance actually.