混凝土结构中NO2-的不均匀性对钢筋宏电池腐蚀行为的影响

摘要

基于宏电池腐蚀理论,将阴极区钢筋和阳极区钢筋分别浇筑成两个独立的砂浆试块,并用导线将其连接成循环电路,通过断开和连接电路来控制钢筋的微电池腐蚀和宏电池腐蚀,再将不同浓度的NO2-溶液分别添加到阴极试块和阳极试块中以模拟其渗透过程,通过比较NO2-作用前后阴阳极钢筋之间宏电池腐蚀电流的大小,来评价阴阳极钢筋表面NO2-的不均匀性对钢筋宏电池腐蚀行为的影响.结果表明:当NO2作用于处于腐蚀状态的阳极钢筋时,能够增加阳极钢筋的极化阻抗,减少阴阳极钢筋间的宏电池腐蚀电位差,降低宏电池腐蚀电流,从而有效抑制宏电池腐蚀;当NO2-主要作用于处于腐蚀状态的阴极钢筋时,阴阳极钢筋间的宏电池电位差的增大易使宏电池腐蚀电流增加,存在加速钢筋宏电池腐蚀的危险.%Based on macrocell corrosion theory,cathodic steel bar and anodic steel bar were casted in two separated cement mortar blocks in which nitrite solution with different concentrations were filled to simulate the penetration process of nitrite ions,then cathodic steel bar and anodic steel bar were connected or disconnected by lead wire to simulate the macrocell corrosion or microcell corrosion.The influence of non-homogeneous nitrite ions on the macrocell corrosion behavior of reinforcing steel was investigated by comparing the magnitude of macrocell current flowing between anodic and cathodic steels.The results indicated that the presence of nitrite only on the surface of anodic steel could increase the macrocell polarization resistance of anodic steel,reduce the macrocell potential difference,decrease the macrocell corrosion currrent and therefore effectively inhibit the macrocell corrosion.The presence of nitrite only on the surface of cathodic steel could enhance the macrocell potential difference,increase the macrocell corrosion currrent and therefore have a risk to accelerate the macrocell corrosion.