Research On Preventing Reflection Cracks Of Asphalt Pavement With High Viscous Asphalt Stress Absorbing Layer

The propagation of cracks in asphalt pavement caused by the semi-rigid base course cracks is one major distress. Adding stress absorbing layer between cracking semi-rigid base course and asphalt overlay is most used to prevent reflection cracks, and asphalt-sand mixture with high content of asphalt is one most effective measure. Based on high viscous asphalt, this paper mainly studied the following four topics:Firstly, FEM (finite element method) was used to analyze the effect of stress absorbing layer in eliminating reflective cracking. The results showed that stress caused by vehicle loads is lower than the HMA admissible tension strength, and cracks propagate under repeated traffic loading. Stress absorbing layer can relieve concentrated stress significantly.Secondly, the effect of different gradations on asphalt sand mixture performance was studied. With special high viscous asphalt and improved Superpave mix design method, this paper designed six different typical mixture gradations and compared their performance. The results showed that the AC gradation and gap gradation have good anti-fatigue ability, high normal temperature strength, are flexible at low temperature and also economical, so they should be first adopted in engineering project.Thirdly, the impact of asphalt performance on stress absorbing layer mixture property was studied, and we put forward asphalt characteristic parameters and recommended criterion, which provided reference for the asphalt choice. Because of the significant correlation of stress absorbing layer mixture fatigue performance and asphalt character such as viscosity@60℃, softening point and penetration, these three asphalt parameters should be satisfied strictly.At last, we studied the technical criterion of stress absorbing layer mixture, and put forward the recommended criterion of volumetric parameters and mixture performance, and provided significative proposition for actual application.Furthermore, we also draw the following conclusions: there are good correlativity between cumulative dissipated energy and mixture fatigue performance, so it can be used as the effective character to evaluate stress...