Electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels

Electrochemical kinetics of corroded steel bars is of importance in evaluating corrosion process and subsequent structural deterioration under different aggressive environments. This paper presents an experimental programme to investigate corrosion kinetics of steel bars in pseudo-transparent concre...

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Main Authors: Bui, Huy Tang, Maekawa, Koichi, Tan, Kang Hai
Other Authors: School of Civil and Environmental Engineering
Format: Article
Language:English
Published: 2024
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Online Access:https://hdl.handle.net/10356/176042
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1760422024-05-13T02:14:03Z Electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels Bui, Huy Tang Maekawa, Koichi Tan, Kang Hai School of Civil and Environmental Engineering Engineering Alkaline property Chloride contamination Electrochemical kinetics of corroded steel bars is of importance in evaluating corrosion process and subsequent structural deterioration under different aggressive environments. This paper presents an experimental programme to investigate corrosion kinetics of steel bars in pseudo-transparent concrete subjected to different levels of chloride contamination and alkalinity in pore solution. The results show that corrosion current density increased with the rise of chloride content in simulated pore solution until Cl−/[OH−] ratio reached around 10. However, further chloride contamination with Cl−/OH−=12.5,15or20 tended to reduce current density. The phenomenon of decreasing corrosion rate and increasing corrosion potential when concrete was severely contaminated by chloride ions has not been widely reported in previous publications. An electrochemical mechanism was proposed based on the concepts of thermodynamics, anodic and cathodic polarisation kinetics to explain this extraordinary phenomenon, in which the decrease of corrosion current density when Cl−/[OH−] ratio increased from 10 to 20 was due to the rises of both anodic and cathodic Tafel slopes. On the other hand, a more neutralised pore solution in pseudo-transparent concrete induced a greater corrosion current density. When pH value was larger than 13, corrosion current density was negligible, while it substantially increased once pH value decreased to lower than 12.5. Ministry of National Development (MND) National Research Foundation (NRF) This research is supported by the National Research Foundation, Singapore, and Ministry of National Development, Singapore, under its Cities of Tomorrow R&D Programme (CoT Award No. COT-V2–2019–1). Any opinions, findings and conclusions expressed in this material are those of the authors and do not reflect the views of National Research Foundation, Singapore and Ministry of National Development, Singapore. 2024-05-13T02:14:03Z 2024-05-13T02:14:03Z 2024 Journal Article Bui, H. T., Maekawa, K. & Tan, K. H. (2024). Electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels. Construction and Building Materials, 421, 135636-. https://dx.doi.org/10.1016/j.conbuildmat.2024.135636 0950-0618 https://hdl.handle.net/10356/176042 10.1016/j.conbuildmat.2024.135636 2-s2.0-85187199727 421 135636 en COT-V2-2019-1 Construction and Building Materials © 2024 Elsevier Ltd. All rights reserved.
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering
Alkaline property
Chloride contamination
spellingShingle Engineering
Alkaline property
Chloride contamination
Bui, Huy Tang
Maekawa, Koichi
Tan, Kang Hai
Electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels
description Electrochemical kinetics of corroded steel bars is of importance in evaluating corrosion process and subsequent structural deterioration under different aggressive environments. This paper presents an experimental programme to investigate corrosion kinetics of steel bars in pseudo-transparent concrete subjected to different levels of chloride contamination and alkalinity in pore solution. The results show that corrosion current density increased with the rise of chloride content in simulated pore solution until Cl−/[OH−] ratio reached around 10. However, further chloride contamination with Cl−/OH−=12.5,15or20 tended to reduce current density. The phenomenon of decreasing corrosion rate and increasing corrosion potential when concrete was severely contaminated by chloride ions has not been widely reported in previous publications. An electrochemical mechanism was proposed based on the concepts of thermodynamics, anodic and cathodic polarisation kinetics to explain this extraordinary phenomenon, in which the decrease of corrosion current density when Cl−/[OH−] ratio increased from 10 to 20 was due to the rises of both anodic and cathodic Tafel slopes. On the other hand, a more neutralised pore solution in pseudo-transparent concrete induced a greater corrosion current density. When pH value was larger than 13, corrosion current density was negligible, while it substantially increased once pH value decreased to lower than 12.5.
author2 School of Civil and Environmental Engineering
author_facet School of Civil and Environmental Engineering
Bui, Huy Tang
Maekawa, Koichi
Tan, Kang Hai
format Article
author Bui, Huy Tang
Maekawa, Koichi
Tan, Kang Hai
author_sort Bui, Huy Tang
title Electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels
title_short Electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels
title_full Electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels
title_fullStr Electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels
title_full_unstemmed Electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels
title_sort electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels
publishDate 2024
url https://hdl.handle.net/10356/176042
_version_ 1800916189153591296