橡胶沥青混合料的动态弯拉模量研究

Study on Dynamic Flexural Modulus of Rubber Asphalt Mixture

为了研究沥青混合料的模量特性,应用UTM材料试验机分别采用四点弯曲和梯形梁两种试验方法测试采用70#基质沥青和橡胶沥青两种不同沥青的混合料动态弯拉模量和相位角,根据时温等效原理计算主曲线移位因子并绘制动态模量主曲线和相位角主曲线,分析橡胶沥青混合料的动态黏弹特性;对比分析两种动态弯拉模量试验方法对沥青混合料动态弯拉模量和相位角的影响。结果表明:沥青混合料动态弯拉模量受温度和荷载频率影响较大,随着温度升高而显著减小,同时随着频率增大而增大;高温时,橡胶沥青混合料的动态模量显著大于70#基质沥青混合料,拥有更好的高温性能;橡胶沥青混合料受频率(温度)影响较小,温度敏感性更好;两种试验方法得到的主曲线在低温阶段趋势一致,在高温阶段有所差别,梯形梁试验最低频率为10 Hz,而四点弯曲试验的最低频率为0. 1 Hz,拟合得到的主曲线高温阶段形状更加完整,能更有效地反映混合料高温时的动态力学性能。

In order to study the modulus characteristics of asphalt mixture,the dynamic bending moduli and phase angles of the mixtures of matrix asphalt No. 70 and rubber asphalt are tested by UTM material testing machine using 4-point bending and trapezoidal beam test methods. According to the time-temperature equivalent principle,the shift factor of the master curve is calculated and the master curves of dynamic modulus and phase angle are drawn to analyse the dynamic viscoelasticity of rubber asphalt mixture. The influences of the 2 dynamic bending modulus test methods on the dynamic bending modulus and phase angle of asphalt mixture are compared and analyzed. The result shows that( 1) the dynamic bending modulus of asphalt mixture is greatly affected by temperature and load frequency,it decreases with the increase of temperature,and increases with the increase of frequency;( 2) at high temperatures,the dynamic modulus of rubber asphalt mixture is significantly greater than that of matrix asphalt mixture No. 70,with better high temperature performance;( 3) the rubber asphalt mixture is less affected by frequency( temperature) and has better temperature sensitivity;( 4) the master curves obtained by the 2 test methods have the same trend in the low temperature stage and different in the high temperature stage,the lowest frequency of the trapezoidal beam test is 10 Hz,while the lowest frequency of the 4-point bending test is 0. 1 Hz. The shape of the master curve obtained by fitting is more complete in the high temperature stage,which can moreeffectively reflect the dynamic mechanical property of the mixture at high temperature.