Numerical Analysis Method And Application For Creep Damage Of Asphalt Mixture

The asphalt pavements, which have the advantages of short periods of construction, good resistance to aquaplane, effective vibration reduction, effective noise reduction, comfort of driving, less dust production, and conveniences in repairs and maintenance, have been widely used in the construction of highways. However, the cracking in cold seasons and the rutting in hot seasons obviously reduce the durability of the asphalt pavements. For the sake of improving the service behavior and the durability, it is essential to research the mechanics properties of the main material of asphalt pavements, asphalt mixture deeply.Based on Two-Step Approach, asphalt mixture can be regarded as a two-phase composite material: coarse aggregates and asphalt mastic (fine aggregates, fines, and asphalt binder). Asphalt mastic is considered as a continuum and isotropic media with viscoelastic properties which can be described with a viscoelastic mechanics model. Coarse aggregates acting as a reinforcing media are distributed among the asphalt mastic. Further more, asphalt mixture can also be simplified and regarded as a kind of uniform isotropic material in macro scale.Considering micro cracks and interstices generally distributed in Asphalt mixture, it is necessary to utilize the damage mechanics theories to analyze the change in material strength due to the change in microstructure of asphalt mixture. Actually, the hardening from creep and the weakening from damage are both happening. Hardening leads to enhancement in material stability; weakening will accelerate the deformation of the material and produce irreversible deformation.An approximate constitutive model considering viscoelasticity and damage for asphalt mixture was derived by describing the Continuum Kachanov Damage Model with a single variable in piecewise form and then coupling it with a simple viscoelastic model. Based on this constitutive model, the general FEM software, ANSYS, was used to stimulate the creep failure of asphalt mixture and the rutting on pavements. The stimulated results have good agreement with the experimental results, which indicates that the proposed viscoelastic constitutive model with damage for asphalt mixture can explain the mechanism of the rutting progress well.