基于CT扫描技术的多孔沥青混凝土抗冻融破坏性能研究

冻融破坏是沥青路面常见的病害形式,目前主要通过马歇尔试件的劈裂强度在冻融环境下的变化情况来间接反映沥青混凝土的抗冻融破坏能力,未揭示出冻融破坏下沥青路面内部结构上的变化,如裂纹、空隙率的变化规律。因此,本研究中采用一种直观的方法来研究沥青混凝土的抗冻融破坏能力,主要是采用工业CT跟踪多孔沥青混凝土内部空隙率在冻融环境下的变化。结果显示沥青混凝土的抗冻融破坏性能与空隙率的分布有很大关系,总体上,在冻融破坏过程中,沥青混凝土试件内部空隙率明显增大的局部区域会造成混凝土局部或整体空隙率的显著变化,严重影响多孔沥青混凝土的抗冻融破坏性能。

The freeze-thaw damage is one main damage form of asphalt pavement. Presently, the freeze-thaw resistance of asphalt mixture is indirectly decided based on the retaining ability of splitting strength of asphalt mixture during the freeze-thaw damage process. While the internal structure changes of asphalt mixture such as the changes of micro-crack and air voids have not been revealed. An intuitive way is adopted in this research, namely using CT to track the change of air voids of porous asphalt mixture under freeze-thaw damage condition. Results suggest that the freeze-thaw damage resistance of porous asphalt mixture is related to the distribution of air voids. In general, the local area with larger air voids, within the asphalt concrete specimen, will result in the significant increase in the air voids of local area or entire specimen during the freeze-thaw damage process, which lowers the freeze-thaw damage resistance of the porous asphalt mixture markedly.