沥青混合料动态模量梯形梁与SPT试验比较研究

Comparison of HMA dynamic modulus between trapezoid beam test and SPT

选用70号基质沥青和SBS改性沥青2种沥青材料、4.75 mm筛孔通过率分别为35%和55%的2种级配组合成4种沥青混合料,分别进行梯形梁和简单性能试验机(SPT)动态模量试验研究。基于时温等效原理,用非线性最小二乘法绘制参考温度为20℃的动态模量和相位角主曲线。研究结果表明:梯形梁和SPT试验得到的动态模量与相位角的主曲线变化趋势一致,但有明显区别;梯形梁试验的主曲线频域更窄,动态模量更小,相位角更大,且所得动态模量和相位角对频率(温度)的变化更敏感;频率(温度)也会对2种试验方法下动态模量和相位角的差异程度产生影响;SBS改性剂可以改善沥青混合料的动态力学性能及其路用性能;使用回归方程对2种试验方法行的动态模量进行转换拟合的相关性良好;加载模式对动态模量的影响显著,应当根据路面结构层的受力状况选择合适的动态模量试验方法。

No.70 matrix asphalt （asphalt with penetration 70） and SBS modified asphalt of two gradations with 4.75 mmsieve passing percent being 35% and 55% were used to make four asphalt mixes to conduct dynamic modulus tests usingtrapezoid beam test and simple performance tester （SPT）. Master curves of dynamic modulus and phase angle atreference temperature 20 ℃ were plotted based on temperature-time transition principle using non-linear least squaremethod. The results show that trends of the master curves of trapezoid beam test and SPT are the same. Compared with SPT, the master curve scope of trapezoid beam test is smaller, and the dynamic moduli is smaller, while the phase angle islarger; dynamic modulus and phase angle of trapezoid beam test are more sensitive to frequency （temperature） changes.The differences of dynamic modulus and phase angle between the two methods are influenced by frequency（temperature）.SBS modifier can improve dynamic mechanical property and pavement performance of asphalt mixes.Regression equation for the dynamic moduli transformation of the two methods indicates that good correlation betweenthe dynamic modulus of the two methods can be obtained. Load modes affect dynamic modulus, and appropriate testmethod should be selected according to the stress state of pavement.