基于电化学腐蚀的桥梁钢筋混凝土耐腐蚀性试验研究

Experimental Research on Corrosion Resistance of Bridge Reinforced Concrete Based on Electrochemical Corrosion

针对沿海地区以及冬季除冰盐大量使用所造成的氯盐腐蚀桥梁的情况,以沿海沪通铁路工程为依托,使用施工现场的钢筋、水泥等原材料,制作三组钢筋混凝土试件,将其分别浸泡在摩尔质量分数为1 mol/L、2 mol/L和3.5 mol/L的氯化钠溶液中,利用电化学方法在不同时间点测出溶液中钢筋混凝土试件中钢筋的腐蚀极化曲线,然后再使用塔菲尔外推法对测出的数据进行拟合计算得到腐蚀电位、腐蚀电流密度和腐蚀速率值,最后利用上述三种腐蚀状态的评价指标对比分析浸泡在不同氯离子含量溶液中钢筋混凝土的腐蚀状况。结果表明,氯化钠对混凝土中钢筋的腐蚀明显,基本呈现出腐蚀速度先逐渐加快后减弱最后再加速的趋势;随着溶液中氯离子含量的增加,钢筋混凝土中钢筋的腐蚀量增大,钢筋的整体腐蚀速度也越快,且在中前期腐蚀速度减弱的现象也越明显。

In view of the situation of the chlorine salt corrosion bridge caused by the heavy use of deicing salt in winter and coastal chloride environment, on the basis of Hu Tong Railway Project, 3 groups of reinforced concrete specimens were made in the experiment by using the steel, cement and other raw materials at the construction site. Then, they were soaked in sodium chloride solutions of 1 mol/L, 2 mol/L, and 3.5 mol/L, respectively, and the polarization curves of reinforced concrete in solution at different time points were measured by electrochemical methods. In addition, Tafel extrapolation, a nonlinear least-squares method, was used to fit the measured data. The corrosion potential, corrosion current density, and corrosion rate were calculated from the software included in the electrochemical workstation. Finally, the corrosion status of reinforced concrete soaked in different concentrations of sodium chloride solution were compared and analyzed using the above three evaluation indicators of corrosion status. The results show that the sodium chloride solution can significantly corrode steel in concrete, and the corrosion law basically shows that the corrosion rate in the early period is gradually increasing, then weakened, and then accelerated; The more concentrated the concentration of sodium chloride solution, the greater the amount of corrosion of steel bars in reinforced concrete, the faster the corrosion rate, and the phenomenon of weakening corrosion at early and middle stages is more obvious.