大空隙沥青混合料内部冻融损伤特征

Characteristics of Internal Freeze-Thaw Damage of Porous Asphalt Mixture

通过冻融劈裂试验,得到大空隙沥青混合料冻融循环前后劈裂强度。结合CT测试技术,得到试件在冻融劈裂前后不同层位的图像。分析大空隙沥青混合料试件在冻融劈裂后内部损伤的状况,并利用损伤变量对混合料内部微观结构的变化进行对比分析。分析结果表明:随着冻融循环作用次数的增加,大空隙沥青混合料试件的劈裂强度逐渐下降;混合料试件冻融后劈裂破坏多发生在试件初始空隙分布密集处,裂缝的扩展方向与初始空隙的方向基本一致;空隙大的沥青混合料试件其力学性能较差,且空隙率大的层位损伤变量增加比空隙率小的层位损伤变量增加更多。

With freeze-thaw splitting test, this paper introduces the splitting strength of the porous asphalt mixture before and after freeze-thaw cycle. With the help of CT test technique, the images of different layers of the specimen before and after freeze-thaw splitting were obtained. Status of the internal damage after freeze-thaw splitting of the porous asphalt mixture was analyzed, and the change of the microstructure of the mixture was comparatively analyzed by using the damage variables. Results show that with the increase of the number of freeze-thaw cycles, the splitting strength of the porous asphalt mixture decreases gradually. The splitting fracture of the mixture specimen occurs at the concentrated area of initial void of the specimen, and the direction of the crack is basically the same as the direction of the initial void; The more porous asphalt mixture specimen has limited mechanical performace and layer damage increment variable is much higher than that of the less porous specimen.