考虑触变性的沥青疲劳过程分析

Analysis of Fatigue Process of Asphalt Considering Thixotropy

为了深入研究沥青的疲劳机理,解决现有沥青疲劳机理中没有考虑触变性的影响这一关键问题,对4种沥青进行了稳态剪切试验、疲劳试验和愈合试验。根据试验结果建立了沥青的触变模型,分析了触变性对沥青疲劳过程的影响,并将触变性的影响从沥青的疲劳过程中分离出来。试验结果表明:指数触变模型可以较好地拟合稳态剪切试验下沥青粘度与剪切时间的关系;沥青抗剪切能力随着间歇时间的增加逐渐恢复;沥青的动态模量-相位角关系曲线可以较好地反映触变性对沥青疲劳过程的影响;触变性影响分离前后,沥青的疲劳曲线存在明显差别,因此仅依据损伤机理研究沥青的疲劳是不合理的,应综合考虑损伤和触变性在沥青疲劳过程中发挥的作用。

For the close study at the fatigue mechanism of asphalt and resolving the problem that the influence of thixotropy was not considered in the existent fatigue mechanism of asphalt, steady-state shear test, fatigue test and healing test of four kinds of asphalts were conducted. Based on the test results, thixotropic model of asphalt was established, the effect o{ thixotropy on fatigue process of asphalt was analyzed, and further analysis was conducted without the consideration of the effect of thixotropy. The results show that exponential thixotropic model can fit the relationship between viscosity and shear time well in steady-state shear test. The ability to resist shearing can heal gradually with increase of interval time. The relation curve of dynamic modulus and phase angle can reflect the effect of thixotropy on fatigue of asphalt. Besides that, the fatigue curve has remarkable difference with and without the consideration of the effect of thixotrophy. All of the results show that it is not suitable to study the fatigue of asphalt only based on damage mechanism, both of the effects of damage and thixotropy should be considered.