利用动态模量主曲线研究沥青混合料水稳定性

摘要

Targeting at that the current moisture stability test methods of asphalt mixtures have deficiencies such as the significant specimen-to-specimen variability and single test temperature condition, the dynamic modulus master curve is employed to improve the evaluation methods.Uniaxial dynamic modulus tests are performed on two types of asphalt mixtures including 70# asphalt and SBS modified asphalt before and after the freeze-thaw cycles, the results of which are used to calculate the dynamic modulus and to further determine the dynamic modulus master curve.The concept of dynamic modulus ratio is proposed and the dynamic modulus ratio at each frequency is calculated.The results indicate that the moisture stability of asphalt mixture increases significantly with the frequency and gradually approaches to that of SBS modified asphalt mixture.Besides, the moisture damage is found to have a more pronounced impact on the viscoelastic properties of asphalt mixture at low frequencies or under high temperature.%针对目前国内评价沥青混合料水稳定性试验方法存在的试件个体差异性明显以及试验温度条件单一等不足,利用动态模量主曲线对评价方法进行改进.采用2种沥青混合料进行单轴压缩动态模量试验,随后将其冻融循环并再次进行试验,绘制冻融前后动态模量主曲线.提出动态模量比的概念,并计算各频率下的动态模量比.结果表明,70#基质沥青混合料水稳定性随频率增大而明显增强并逐渐接近SBS改性沥青混合料,并且水损害对两种沥青混合料低频时(或高温时)的粘弹性质影响均更为显著.