两种流变仪在沥青性能评价方面的应用

Application of Dynamic Shear and Bending Beam Rheometer Evaluation of Asphalt Performance

高温车辙及低温开裂是沥青路面在使用过程中普遍存在的问题。其中沥青作为结合料,其性能的好坏是影响沥青路面使用寿命的重要因素。常规评价沥青性能的方法是利用针入度、软化点、延度、粘度等指标,及三点针入度回归后得到的当量软化点(T800)、当量脆点(T1.2)来评价沥青的使用性能。而SHRP新的评价沥青性能的方法模拟了沥青路面在使用过程中的实际情况,因而在许多方面得到了推广和应用。选用国内外有代表性的几种沥青,按照AASHTO标准方法,用动态剪切流变仪及弯曲梁流变仪对沥青的高、低温性能进行了评价,并与常规评价沥青的方法进行了对比。试验结果表明,利用这两种流变仪评价沥青的使用性能与常规评价指标有很好的相关性。此外,两种流变仪测定的指标能够反映沥青结合料的流变性随荷载、时间、温度的变化而发生的变化,是一种更为合理的评价手段。同时,探讨了影响沥青高温车辙及低温开裂的主要因素。

There are some problems of high temperature tracks and low temperature cracks in application of asphalt. The performances of asphalt are important affecting factors in service life of asphalt pavement. The several index were usually applied to evaluate the performance of asphalt,that are penetration, softening point ,ductility, viscosity and equivalent softening point(T800),equivalent breaking point(T1.2). SHRP method of evaluating the asphalt performance was spread and applied in many ways since it simulated real application condition of asphalt in the period of service. The high and low temperature performance of asphalt was evaluated with dynamic shear and bending beam rheometer, according to AASHTO standard testing method in the research. The asphalt products were selected from a few representative domestic and abroad asphalt products. The mainly factors which influence high temperature tracks and low temperature cracks were discussed and compared with general evaluate methods of asphalt. The results show that there is a good relativity between two methods. Otherwise, the results indicate that the rheology of asphalt binder change with load, time and temperature. It is a reasonable evaluation method.