方波电流对混凝土中钢筋腐蚀的电化学修复效应

Electrochemical Rehabilitation of Square Wave Current on Reinforcement Corrosion in Concrete

为降低电化学修复对钢筋的氢脆作用,对比了恒电流和方波电流2种电场对钢筋混凝土构件进行电化学修复的效果.通过开路电位、线性极化、交流阻抗、拉伸试验及扫描电镜等方法对比分析两种电流施加方式对砂浆中钢筋耐蚀性和力学性能的影响.结果表明:相较于恒电流电化学修复,方波电流作用下的钢筋腐蚀电流密度更小,砂浆保护层电阻、钢筋钝化膜电阻及钢筋电荷转移电阻更大;方波电流电化学修复对砂浆保护层的修复效果更显著,增强了钢筋钝化性能,减小了钢筋腐蚀速率;方波电流还可降低电化学修复阴极极化对钢筋塑性的影响,减少钢筋氢脆风险.

In order to study the effects of square wave current on the electrochemical rehabilitation of concrete structures,two kinds of electric fields,i.e.constant current and square wave current,were used.The open circuit potential,liner polarization,electrochemical impedance spectroscopy,tensile test and scanning electron microscope were used to compare and analyze the influence of electric fields on the corrosion and mechanical properties of the reinforcements in mortars.The results show that the corrosion current density of reinforcement under the square wave electric current is smaller than that under the constant current electrochemical rehabilitation,while the mortar resistance,the resistance of passive film on steel and the reaction resistance are larger than those under the constant current field electrochemical rehabilitation.The electrochemical rehabilitation under the square wave electric field has a more significant effect on the cement mortar layer,enhances the stability of the passive film on reinforcement,and reduces the corrosion rate.The square wave current can reduce the influence of cathodic polarization on the plasticity of reinforcement and decrease its hydrogen embrittlement.