热流变复杂行为对沥青温度应力计算的影响

Influence of thermo-rheological complex behavior on thermal stress calculation of asphalt binder

摘要:

为了完善现有沥青胶结料温度应力计算方法,利用弯曲梁流变试验（BBR）得到沥青材料的蠕变柔量,代入线性粘弹性的Burgers模型的应变-应力关系式得到不同温度下的流变参数,再利用Burgers模型的本构状态方程的解析解,计算沥青层下温度应力的数值解（增量法）,并将计算结果与传统Hopkins & Hamming算法的结果进行对比。结果表明:总体来看两种方法大致吻合,但在较低的温度下（-30 ℃左右）,Hopkins & Hamming算法的结果较增量法偏小,低估了热可逆老化的影响；低温养护对沥青的硬化效果与沥青的流变性质相关,流变性质越复杂的沥青,受到低温养护的硬化效果越明显；当处于低温或者长期加载时,热流变复杂沥青的主曲线会偏离时间温度叠加原理。

Abstract:

For improving the existing thermal stress calculation methods of asphalt binders, the bending beam rheological (BBR) test was performed to obtain the creep compliance of asphalt material, and the strain-stress relationship of the linear viscoelastic Burgers model was introduced to obtain the rheological parameters at different temperatures. The analytical solution of the constitutive equation of state of the Burgers model was used to calculate the numerical solution of the thermal stress under the asphalt layer (incremental method), and the calculation results were compared with the results of the traditional Hopkins and Hamming′s algorithm. Results show that the two methods were basically consistent, but at a lower temperature (around -30 ℃) the results of the Hopkins and Hamming′s algorithm were smaller than those of the incremental method, underestimating the effect of thermally reversible aging. The hardening effect of low-temperature curing on asphalt was related to the rheological properties of asphalt. The more complex the rheological properties of asphalt were, the more obvious the hardening effect of low-temperature curing was. When under low temperature or long-term loading, the rigidity master curve of the thermo-rheological complicated asphalt deviated from the timek-temperature superposition principle.