Evaluation Based On The Viscoelastic Properties Of Asphalt Mixture Fatigue

Fatigue cracking is the main pavement distress in the field. Fatigue is a very important control index, and a lot of countries use this index to design the asphalt pavement. Many kinds of fatigue tests have been developed to evaluate the fatigue performance of asphalt mixtures by scholars. As the viscoelasticity is a character of asphalt, the character will influences the property of fatigue. But few studies were focused on the the property of asphalt material, so the evaluation method couldn’t reveal the essentials of the mixture fatigue performance. All the evaluation methods have some limitations and imperfections. So explore the influence of the viscoelasticity character to the mixture fatigue performance and the reason of failure of mixture is very necessary.To solve this problem, the paper studied mortar which makes the most contribution to the mixture viscoelasticity firstly. With the utilization of dynamic shear rheometer(DSR), the paper researched 11 kinds of mortars which includes different ratio of filler bitumen and different bitumen types. At first, the researcher used frequency sweeping test to get the index of viscoelasticity. Through comparing the size of viscoelastic parameters to analyze the viscoelastic law and got the master curve to get further viscoelasticity analysis. On this basis, the paper got the accumulated damage of asphalt mortar by linear amplitude sweeping test. The C-S curve is fitted with viscoelastic continuum damage model(VECD), and the fatigue property of different material are carried out based on these model parameters.Then the paper studied the static viscoelastic of asphalt mixtures. Trough the Burgers constitutive model, research analyzed the different mix grading 、 asphalt content、asphalt type effect on instaneous elastic modulus and viscoelastic proportion coefficient. The paper also studied asphalt mixtures viscoelastic under dynamic load. Dynamic modulus test was carried out with mathematical method for fitting. The index which can characterize the mix viscoelastic was got based on the analyze of the master curve of complex modulus、phase angel and storage modulus.Finally, the paper evaluate the fatigue performance of asphalt mixture with different amount and types of asphalt and different gradation. With the basic of the analysis above, the paper confirmed the influence of asphalt property to the fatigue performance utilized viscoelasticity parameter. By analysis the index of viscoelasticity which is related to the fatigue performance of mixture directly, the paper confirmed the viscoelastic range of the best fatigue performance.The paper researched how the asphalt mixture viscoelasticity influence the fatigue performance. The research result provided a new method and basic to asphalt mixture fatigue performance and asphalt mixture design.