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In-situ monitoring of pH and Cl− concentration and rebar corrosion at the rebar/mortar interface
Highlights pH and [Cl−] monitoring in cement mortar was realized using electrochemical sensors. Emembrane was confirmed to bring errors in [Cl−] and pH determination in pore water. pH of pore water decreased from 13.4 to 11.5 in mortar immersed in NaCl solution. [Cl−] increased from 0.005 to 1.37 mol∙L−1 near the rebar/mortar interface. The passive rebar surface became active with the evolution of pore water chemistry.
Abstract This study performed in-situ monitoring of pH and [Cl−] in pore water near the rebar/mortar interface using embedded electrochemical sensors (i.e., IrOx and Ag/AgCl electrodes). Membrane potential (E membrane), which is the potential difference across the mortar/bulk electrolyte interface, was found to bring significant errors in determining pH and [Cl−]. These errors could be eliminated by measuring the potential of the sensors against the home-made-embedded reference electrode. In a long-term immersion experiment, the corrosion of steel rebar was recorded using electrochemical impedance spectroscopy. Results showed that over the 75 days of immersion experiment, [Cl−] in pore water near the rebar/mortar interface increased from 0.005 mol∙L−1 (at day 2) to 1.37 mol∙L−1, while pH decreased from 13.4 to 11.5. With the evolution of [Cl−] and pH, the corrosion of steel surface was accelerated due to passive film breakdown. The “passive to active” transition occurred when [Cl−] was ≥0.25 mol∙L−1 and pH was ≤12.1.
In-situ monitoring of pH and Cl− concentration and rebar corrosion at the rebar/mortar interface
Highlights pH and [Cl−] monitoring in cement mortar was realized using electrochemical sensors. Emembrane was confirmed to bring errors in [Cl−] and pH determination in pore water. pH of pore water decreased from 13.4 to 11.5 in mortar immersed in NaCl solution. [Cl−] increased from 0.005 to 1.37 mol∙L−1 near the rebar/mortar interface. The passive rebar surface became active with the evolution of pore water chemistry.
Abstract This study performed in-situ monitoring of pH and [Cl−] in pore water near the rebar/mortar interface using embedded electrochemical sensors (i.e., IrOx and Ag/AgCl electrodes). Membrane potential (E membrane), which is the potential difference across the mortar/bulk electrolyte interface, was found to bring significant errors in determining pH and [Cl−]. These errors could be eliminated by measuring the potential of the sensors against the home-made-embedded reference electrode. In a long-term immersion experiment, the corrosion of steel rebar was recorded using electrochemical impedance spectroscopy. Results showed that over the 75 days of immersion experiment, [Cl−] in pore water near the rebar/mortar interface increased from 0.005 mol∙L−1 (at day 2) to 1.37 mol∙L−1, while pH decreased from 13.4 to 11.5. With the evolution of [Cl−] and pH, the corrosion of steel surface was accelerated due to passive film breakdown. The “passive to active” transition occurred when [Cl−] was ≥0.25 mol∙L−1 and pH was ≤12.1.
In-situ monitoring of pH and Cl− concentration and rebar corrosion at the rebar/mortar interface
Wang, Yuanxia (author) / Liu, Nazhen (author) / Liu, Xiangju (author) / Liu, Xinyu (author) / Sun, Congtao (author) / Chen, Xuwei (author) / Hou, Baorong (author)
2023-07-30
Article (Journal)
Electronic Resource
English
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