This work uses X-ray computed micro tomography (XCT) to investigate the role of the critical degree of saturation (DOS) and air void system on the crack propagation of portland cement mortar subjected to freeze-thaw cycles. Three-dimensional imaging before and after freezing allow quantitative measurements on the location and volume of the formation of new cracks and the infilling of air voids. Cracks present before freeze-thaw cycles are observed to extend and new cracks initiate from the paste-aggregate interface. In addition, calcium-rich products were observed to fill > 20% of the volume of the air voids with a diameter < 50 μm. These observations provide insights into the freeze-thaw performance of mortar and are a step in understanding the damage in concrete.

这项工作使用X射线计算机断层扫描（XCT）来研究临界饱和度（DOS）和气孔系统在经历冻融循环的硅酸盐水泥砂浆裂缝扩展中的作用。冻结前后的三维成像可以对新裂纹的形成位置和体积以及气泡的填充进行定量测量。观察到冻融循环之前存在的裂纹扩展，并且新的裂纹从糊料-骨料界面开始。此外，观察到富含钙的产品填充了直径小于50μm的气孔的> 20％。这些观察结果可洞察砂浆的冻融性能，并且是理解混凝土损伤的一步。