混凝土裂缝表征方法研究进展及裂缝对氯离子传输影响

氯离子侵蚀导致混凝土中钢筋锈蚀,是钢筋混凝土耐久性劣化的主要表现形式,然而混凝土裂缝的存在将加快氯离子在混凝土中的传输并缩短钢筋混凝土的服役寿命。首先对已有的裂缝表征方法进行了介绍,包括线性位移传感器、图像分析法、CT扫描等。然后综述了带有裂缝的混凝土基体中氯离子扩散的影响因素,重点介绍了裂缝的宽度、水灰比、矿物掺合料、龄期、荷载等因素对氯离子扩散行为的影响。结果表明当裂缝宽度在50~200μm之间时,对氯离子扩散系数的影响最大,在此区间内,氯离子扩散系数随着裂缝宽度的增加而增大;其余因素也对氯离子扩散系数有不同程度的影响。

Review on characterization methods of concrete cracks and effects of cracks on chloride ion transport

Chloride ion erosion causes corrosion of steel in concrete,which is the main form of deterioration of reinforced concrete durability.However,the presence of concrete cracks will accelerate the transmission of chloride ions in concrete and shorten the service life of reinforced concrete.The existing fracture characterization technology and equipment are introduced which including LVDT,image analysis,CT scanning,etc.And the influencing factors of chloride ion diffusion in concrete matrix with cracks are reviewed.The effects of crack width,water-cement ratio,mineral admixture,age,load and other factors on chloride ion diffusion behavior are highlighted.The results show that when the crack width is between 50 μm and 200 μm,the diffusion coefficient of chloride ion has the greatest influence.The diffusion coefficient of chloride ion increases with the increase of crack width.The other factors also have the diffusion coefficient of chloride ion different degrees of impact.