多孔沥青混凝土多场动态蠕变过程的细观表征

Microscopic Characterization of Porous Asphalt Concrete During Multi-physics Dynamic Creep Process

为了研究多孔沥青混凝土(PAC)高温蠕变的细观退化过程,采用多物理场动态蠕变试验和图像分析方法研究多孔沥青混凝土蠕变过程的细观结构变化,表征了多孔沥青混凝土内部空隙在蠕变3个阶段中的变化规律。结果表明:PAC空隙率和连通空隙率在多物理场动态蠕变第一阶段显著减小,直径介于1 mm和5 mm之间的空隙比例上升,其余空隙比例减小,降雨中条件下PAC空隙的压密程度比干燥条件下要更大;多物理场动态蠕变第二阶段中,PAC空隙率和连通空隙率增大,空隙数量整体上升,部分直径介于1 mm和5 mm之间的空隙被压密成直径小于1 mm的空隙;在第三阶段,PAC破坏时空隙率和连通空隙率继续增大,直径小于1 mm的空隙占比持续上升,试件上部空隙数量减小而中部空隙数量增大,在试验结束时出现压剪破坏。

To study the microscopic degradation process of high-temperature creep of porous asphalt concrete,the microstructure changes of porous asphalt concrete were studied by using multi-physics dynamic creep test and image analysis methods.The inner voids of porous asphalt concrete at 3 stages of creep processes were characterized.The result indicates that the porosity and connected porosity of PAC decrease significantly in the first stage of multi-physics dynamic creep.The proportion of voids between 1 mm and 5 mm in diameter increases.The proportion of other voids decreases.The compaction degree of mixture voids under rainfall condition is greater than that under dry condition.In the second stage of multi-physics dynamic creep,the PAC porosity and connected porosity increase,the number of voids increase,and some voids with diameters between 1 mm and 5 mm are compacted into voids with the diameter of less than 1 mm.In the third stage,the porosity and connected porosity of the mixture continue to increase.The proportion of voids with the diameter of less than 1 mm continue to increase.The number of voids in upper part of the specimen decrease,and the number of voids in the middle increase.The compressive shear failure of the asphalt concrete occurres at the end of test.