关于混凝土钢筋锈蚀等效电路模型中各元件的物理意义理解不尽相同. 为了对模型元件的物理意义给出合理解释, 设计了由氯盐侵蚀和混凝土碳化导致钢筋锈蚀的两种加速试验. 通过对钢筋锈蚀试块阻抗谱特征的分析研究, 对模型元件的物理意义给出了合理解释. 研究发现, 氯盐锈蚀试块具有三段容抗弧, 即三个时间常数; 而碳化锈蚀试块阻抗谱与钝化钢筋试块阻抗谱都只有两个容抗弧, 即两个时间常数, 可以使用相同的等效电路模型来表示. 随着锈蚀的逐渐开展, 低频段的容抗弧逐渐收缩. 当环境湿度升高时, 阻抗谱中高频段与低频段容抗弧均发生收缩, 所表现的物理意义为混凝土电阻率的降低和钢筋极化电阻的降低. 最后, 本文提出了等效电路的简化模型, 并通过试验验证了简化模型的合理性.
Understandings of the physical significance of elements in equivalent circuit model of rebar corrosion in concrete are not quite similar. In order to give a reasonable explanation, experiments of rebar corrosion in concrete induced by chloride penetration and carbonation were designed, and then the characteristics of electrochemical impedance spectroscopy(EIS) of test specimens were carefully examined. It was found from the test results that, for the rebar corrosion induced by chloride attack, three capacitance arcs were observed in impedance spectroscopy. However, for the rebar corrosion induced by carbonation, there exsited only two capacitance arcs in impedance spectroscopy, which corresponded with characteristics of rebar in passivation state. Low frequency capacitance arc shrank gradually with corrosion going on. As relative humidity increasing, high frequency and low frequency capacitance arcs both shrank, which meant decreasing of concrete resistivity and polarization resistance of rebar. Finally, a simplified equivalent circuit model was proposed and verified by experiment.
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