低温下沥青混凝土的拉伸变形特性

Tensile deformation of asphalt mixtures under low temperature

将数字图像测量系统替代传统的位移传感器采集系统应用于间接拉伸试验,得到沥青混凝土细观结构上的位移场分布和破坏形态。分析了粗骨料和细骨料结构沥青混凝土的低温抗裂性能,并研究了不同状态下材料的轴向、径向和体积应变特性以及泊松比的变化。数据分析表明:材料的弹性压缩和剪切膨胀与荷载作用历史紧密相连,反映了材料的结构性变形过程;沥青混凝土的低温开裂更多地依靠粒料与沥青结合料的界面黏聚力,良好的骨架结构是材料抵抗拉伸变形的前提。

A digital image processing system instead of the traditional displacement sensor data acquisition system was used to the indirect tensile test of asphalt mixtures, and their displacement field and damage form in meso-structure were recorded. The low-temperature tensile perforrnances of asphalt mixtures with fine and coarse aggregate structures were analyzed and the variations of the axial, radial and volume strains and Poisson ratio of asphalt mixtures under different states were investigated. Data analysis indicates that the elastic compression and shear dilatation of asphalt mixture are closely related to its loading history, reflecting its structural deformation process. The lowtemperature cracking of asphalt mixtures is more dependent on the interface cohesive strength between granule and asphalt binder. The good skeleton structure is the prerequisite for the resistance of asphalt mixture against the tensile deformation.