The work aims to study pH thresholds of rebar corrosion of different types of buffer solution and simulated con-crete pore solution under carbonation.The electrochemical impedance spectroscopy was used for electrochemical behavior measurement of rebar specimens in buffer solution and simulated concrete pore solution of different pH and preparation meth-ods.Different equivalent circuits were selected for fitting,so as to explain the electrochemical process of steel specimen during measurement,while the measurement and simulation results were used to judge the corrosion condition of specimens in combi-nation with the typical macro morphology of working electrodes,through which the pH thresholds of rebar corrosion corre-sponding to different solution were given.The result showed that due to the different ionic environment,the pH threshold of re-bar corrosion in each buffer solution and simulated concrete pore solution was different,ranging from 9 to 10.5.In conclusion,the introduction of HCO3-and CO32-promotes the corrosion of rebar in concrete and the rebar corrosion is more likely to initiate with lower pH.The reliability of judgement on corrosion condition of rebar in concrete based on pH values is limited.
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