模拟混凝土孔溶液对钢筋钝化的影响

Influence of Simulated Concrete Pore Solution on Reinforcing Steel Passivation

通过线性极化、电化学阻抗谱、循环极化和Mott-Schottky曲线的测试,研究了不同模拟混凝土孔溶液(不同pH值和不同阴离子)对钢筋钝化的影响.结果表明:随着模拟混凝土孔溶液pH值的升高,钢筋钝化膜更容易生成,且更稳定.在pH值为13.63的模拟混凝土孔溶液(CP)中,钢筋钝化膜生成且稳定大约需要7d;在pH值为12.54的模拟混凝土孔溶液(CH)中大约需要10d;而在pH值为11.00的模拟混凝土孔溶液(CN)中钢筋无法生成稳定的钝化膜.掺加大量矿物掺合料会明显降低混凝土孔溶液的pH值,故从钝化膜生成与稳定角度考虑,掺合料的掺量应有所控制.CP中掺入微量SO42-和SiO23-后,明显增加了钢筋的极化电阻,促进了钢筋钝化膜的生成,其中SiO32-的作用更明显.

The effect of simulated concrete pore solutions with different pH values and some anions on the passivation of reinforcing steel was studied by means of linear polarization resistance（LPR）,electrochemical impedance spectroscopy（EIS）,cyclic polarization and Mott-Schottky curves.The results indicate that the increase in pH value facilitates the formation of passive film of reinforcing steel.It has been found that for the reinforcing steel to be passivated,it needs to be kept about 7 d in CP solution with pH=13.63 and 10 d in CH solution with pH=12.54.However,passive film may not be perfectly formed in CN solution with pH=11.00.The pH value of concrete pore solution decreases evidently when lots of supplementary cementitious materials（SCMs） are added.Therefore,the amount of SCMs should be controlled in view of the formation and stability of passive film.The results also show that the addition of SO2-4 and SiO2-3 in CP solution allows the increase in the polarization resistance,promoting the passivation of reinforcing steel,particularly for SiO2-3.