钢筋混凝土不同劣化阶段的电化学特征

Electrochemical Characteristics of Steel Reinforced Concrete at Different Deterioration Stages

针对现有氯盐侵蚀混凝土结构耐久性研究中模拟氯盐侵蚀环境方法的弊端,采用电迁移加速氯离子侵蚀的方法,以较快的速度模拟出不同劣化阶段的钢筋混凝土试件.通过分析电迁移氯离子侵蚀后钢筋表面状态的检测结果和劣化状况,验证了电迁移法制备不同劣化阶段试件的有效性和准确性,揭示了混凝土不同劣化阶段的电化学特征.结果表明:电迁移法较预掺氯盐法更能真实反应不同劣化阶段的钢筋混凝土结构;混凝土中钢筋由钝化状态转入锈蚀状态时,阳极极化曲线变缓,阴极极化曲线变陡;随着氯离子侵蚀,钢筋劣化程度增加,阳极反应交换电流密度增大,钢筋的腐蚀电位逐步向阳极反应平衡电位偏移.

In view of the disadvantages of the existing methods of simulating chloride corrosion environment in the concrete durability study,using the electromigration method to accelerate the intrusion of chloride ions,concrete specimens with different durability stages can be simulated and prepared at a faster rate.By analyzing the detection results and deterioration of the surface state of the steel after electromigration instrusion of chloride ions,the effectiveness and accuracy of the electromigration method for preparing specimens with different degradation stages were verified,and the electrochemical characteristics of different durability stages of concrete durability was revealed.The results show that,compared with the method of pre-mixed chloride,the electromigration method can simulate the chloride intrusion more effectively in different deterioration stages.When the reinforcement begins to rust,anode polarization curve becomes slower,but cathode polarization curve becomes steeper.With chloride ion erosion,the deterioration degree of reinforcement is increased,the exchange current density of anode is also increased,and then the corrosion potential gradually moves to anode reaction equilibrium potential.