混凝土拉伸荷载条件下细观破损过程的CT试验研究

对静力、动力拉伸荷载条件下混凝土的细观破损过程进行了CT试验研究,获得了试样内部裂纹萌生、扩展、贯通的全过程CT图像。通过对CT图像及图像兴趣区中整体统计区域、局部统计区域CT数均值的分析,研究了混凝土拉伸荷载条件下细观破损过程。结果表明:静力拉伸荷载条件下,裂纹在界面的薄弱区域形成后逐渐往相邻的薄弱部位扩展,两个统计区域CT数均值呈降低趋势,试样破坏时伴有少量骨料被拉断的现象;动力拉伸荷载条件下,裂纹从界面薄弱区域形成后追随最快的路径扩展,局部统计区域CT数均值呈下降趋势,而整体统计区域CT数均值变化幅度较小,破坏后骨料沿界面脱离砂浆粘结,且试样破裂面更为平整;由于加载速率的提高,骨料被拉断的现象非常显著。

CT test analysis of meso damage and fracture process of concrete under tensile loading

The real time scanning observation on meso damage process in concrete was carried out using CT technology .CT images of crack propagation ,coalescence and failure were obtained under static and dynamic tension .Meso‐damage mechanism of concrete under tension was analyzed the mean CT numbers in large statistical region small statistic region of scanning layers ROI .The results showed that the cracks developed in the interface of weak region and expanded to adjacent weak partsthe mean CT numbers of the two statistical regions showed decreasing trend . Parts of aggregates were ruptured when the concrete was damaged under static tension .While in small statistic region ,the cracks developed in the interface of weak region and expanded along the fastest path ,and the mean CT numbers showed a decreasing trend The mean CT numbers in large statistical region changed slightly . The aggregate divorced from mortar along interface ,and the failure plane was smoother when the concrete was damaged under dynamic tension .So , the aggregate was ruptured obviously because the loading rate was higher .