混凝土中钢筋腐蚀过程的极化曲线分析

为了确定混凝土中钢筋锈蚀速率的控制因素,运用腐蚀极化曲线图分析活化钢筋阴阳极极化曲线和腐蚀电流随环境相对湿度的变化规律,并讨论在干湿循环过程中混凝土中钢筋的锈蚀过程.结果表明,有锈蚀产物存在时,锈蚀产物中FeOOH可以取代氧成为钢筋锈蚀过程的阴极去极化剂,钢筋的总腐蚀电流为氧去极化和锈蚀产物去极化产生的腐蚀电流的加和.钢筋的总腐蚀电流随着环境相对湿度的提高而增大,和氧在混凝土中的扩散速率的变化趋势截然相反,从而证明氧仅是混凝土内钢筋开始的锈蚀的必备条件,但却不是混凝土中钢筋锈蚀过程控制因素.

Study on polarization curve diagrams of steel corrosion in concrete

In order to confirm the controlling factor of steel corrosion rate in concrete,variation of cathodic and anodic polarization curves and corrosion rate of active steel under different relative humidity was analyzed with the polarization curve diagrams.Based on metal corrosion theory,the corrosion mechanism of the reinforcing bar in concrete in the process of wet and dry cycles was fully explained.The results show that after the corrosion products are enough,FeOOH in corrosion layer can act as depolarizer instead of oxygen.The total corrosion current is the summation of corrosion currents produced by oxygen depolarization and corrosion products depolarization.When concrete dries,the total corrosion rate of active steel decreases while the diffusion rate of oxygen in the concrete increases.So the oxygen is one of the factors that influence corrosion rate but is not the factor controlling corrosion process of steel in concrete.