含缺陷钢筋混凝土锈蚀特征

Corrosion characteristics of defective reinforced concrete

为深入理解钢筋的锈蚀机理及模拟自然锈蚀现象,采用X射线计算机断层扫描技术(X-ray computed tomography,XCT),无损跟踪并分析钢筋保护层中包含初始缺陷的样品腐蚀过程,对比分别在界面、中部和表面处含有缺陷的样品在通电和干湿循环两种加速锈蚀实验下的三维锈蚀形貌和破坏情况.结果表明,干湿循环倾向于产生空间上不均匀分布的大面积锈坑,通电会产生均匀分布的微小锈坑;干湿循环锈蚀在相近的真实锈蚀率下会普遍产生比通电加速锈蚀更大的裂缝宽度,更贴近真实锈蚀情况;不同的缺陷位置以及加速锈蚀方法对于界面锈蚀产物积累的影响并不明显,但保护层开裂与缺陷位置有关,靠近样品外侧的缺陷更易导致样品开裂.

In order to further understand the corrosion mechanism of reinforcement and simulate the natural corrosion phenomenon,we use X-ray computed tomography(XCT)to nondestructively trace and analyze the corrosion process of the specimens containing the initial defect in protective layer.We compare three-dimensional corrosion morphology and damage of specimens containing interface,middle and surface defects under two accelerated corrosion experiments:the applied current experiment and the wet-dry cycles(W/D)experiment.The results show that W/D tends to produce spatially randomly distributed large pits,while energization produces uniformly distributed tiny pits.W/D corrosion produces generally larger crack widths at similar actual corrosion degree than those with energized accelerated corrosion,which is closer to the natural corrosion.The effects of different defect locations and accelerated corrosion methods on the accumulation of interfacial corrosion products are not obvious,but the cover cracking is obviously related to the defect location,the closer the defect is to the outside of the specimen,the more likely it leads to the cracking of specimen.