Study on pH Threshold of Rebar Corrosion in Concrete under Carbonation Condition
Received:January 15, 2024  Revised:February 26, 2024
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DOI:10.7643/issn.1672-9242.2024.03.011
KeyWord:concrete  rebar corrosion  carbonation  electrochemical impedance spectroscopy  pH threshold  pore solution  buffer solution
                 
AuthorInstitution
LI Qing Powerchina Huadong Engineering Co., Ltd., Hangzhou , China
SHU Wei Offshore Oil Engineering Co., Ltd., Tianjin , China
JIA Huifeng Offshore Oil Engineering Co., Ltd., Tianjin , China
YIN Yexiong School of Naval Architecture and Ocean Engineering, Dalian University of Technology, Liaoning Dalian , China
XU Yunze School of Naval Architecture and Ocean Engineering, Dalian University of Technology, Liaoning Dalian , China
HUANG Yi School of Naval Architecture and Ocean Engineering, Dalian University of Technology, Liaoning Dalian , China
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Abstract:
      The work aims to study pH thresholds of rebar corrosion of different types of buffer solution and simulated concrete 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 methods. 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 combination with the typical macro morphology of working electrodes, through which the pH thresholds of rebar corrosion corresponding to different solution were given. The result showed that due to the different ionic environment, the pH threshold of rebar 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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