Fatigue characteristic of asphalt

Fatigue has been one of the hot topics all the time in the world. The fatigue characteristic of asphalt has particularity because of its viscoelasticity characteristic. At present, the healing characteristic of asphalt has been found, that is when the loading is stopped the modulus of asphalt can recover slowly. So it is essential to study the fatigue characteristic of asphalt at different loading modes. The fatigue characteristic of asphalt under continuous loading mode has been studied, their fatigue characteristics were evaluated by four kinds of indexes (50%G*,DER,DR,δ) and the healing ability of asphalt has been studied. The results show that the fatigue performance of asphalt descends with the loading increasing. When the loading is bigger, the modulus decreases with the times of loading increasing, and when the loading is smaller, there is stiffness phenomenon. The indexes (50%G*,DER,DR,δ) have some deficiency in evaluating the fatigue characteristic of asphalt. The healing characteristic has an important performance on the fatigue characteristic of asphalt. The healing rate at the initial period after stopping loading is bigger than later. When the time is long enough, the modulus can recover to the initial value, but the phase angle changed.