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Evaluation of Ag/AgCI sensors for in-situ monitoring of freee chloride concentration in reinforced concrete structures

Pargar, F. and Koleva, D. A. and Copuroglu, O. and Koenders, E. A. B. and Breugel, K. van (2014):
Evaluation of Ag/AgCI sensors for in-situ monitoring of freee chloride concentration in reinforced concrete structures.
University College London, In: Young Researchers’ Forum II: Construction Materials, London, UK, 19th February 2014, [Online-Edition: http://resolver.tudelft.nl/uuid:95faa6e6-bfa9-4f7b-8e25-de4a...],
[Conference or Workshop Item]

Abstract

The level of free chloride concentration in reinforced concrete structures essentially determines the onset of steel corrosion initiation and further propagation. One of the well-known methods for monitoring free chloride concentration is using silver/silver chloride electrodes (Ag/AgCl). These electrodes are sensitive mainly to chloride ions and establish a certain electrochemical potential depending on the chloride ion activity in the environment. Although the functioning principles of these electrodes are well-established, their use in concrete is challenging when durability and practical engineering issues are considered. In order to be able to accurately determine free chloride content in concrete, it is important to evaluate the performance of Ag/AgCl electrodes (sensors) in strong alkaline environments i.e. those existing in non-carbonated concrete (pH~12–13.5). Furthermore the linear response of these sensors to a wide range of chloride concentrations in highly alkaline medium, as well as their sensitivity to pH changes, need a more in-depth investigation. In this paper the response of Ag/AgCl electrodes in simulated pore solutions having different chloride concentrations and different pH values was studied. The electrodes were calibrated in cement extract solution, distilled-water and simulated pore solution. The results show that at chloride concentrations of \textgreater 4 mM the effect of pH on the response of the sensors is insignificant which makes using Ag/AgCl sensors in concrete feasible i.e. this concentration is much lower than the generally reported thresholds for corrosion initiation. Keywords: Ag/AgCl electrode, cement extract solution, free chloride, pH value, pore solution.

Item Type: Conference or Workshop Item
Erschienen: 2014
Creators: Pargar, F. and Koleva, D. A. and Copuroglu, O. and Koenders, E. A. B. and Breugel, K. van
Title: Evaluation of Ag/AgCI sensors for in-situ monitoring of freee chloride concentration in reinforced concrete structures
Language: English
Abstract:

The level of free chloride concentration in reinforced concrete structures essentially determines the onset of steel corrosion initiation and further propagation. One of the well-known methods for monitoring free chloride concentration is using silver/silver chloride electrodes (Ag/AgCl). These electrodes are sensitive mainly to chloride ions and establish a certain electrochemical potential depending on the chloride ion activity in the environment. Although the functioning principles of these electrodes are well-established, their use in concrete is challenging when durability and practical engineering issues are considered. In order to be able to accurately determine free chloride content in concrete, it is important to evaluate the performance of Ag/AgCl electrodes (sensors) in strong alkaline environments i.e. those existing in non-carbonated concrete (pH~12–13.5). Furthermore the linear response of these sensors to a wide range of chloride concentrations in highly alkaline medium, as well as their sensitivity to pH changes, need a more in-depth investigation. In this paper the response of Ag/AgCl electrodes in simulated pore solutions having different chloride concentrations and different pH values was studied. The electrodes were calibrated in cement extract solution, distilled-water and simulated pore solution. The results show that at chloride concentrations of \textgreater 4 mM the effect of pH on the response of the sensors is insignificant which makes using Ag/AgCl sensors in concrete feasible i.e. this concentration is much lower than the generally reported thresholds for corrosion initiation. Keywords: Ag/AgCl electrode, cement extract solution, free chloride, pH value, pore solution.

Publisher: University College London
Divisions: 13 Department of Civil and Environmental Engineering Sciences
13 Department of Civil and Environmental Engineering Sciences > Institute of Construction and Building Materials
Event Title: Young Researchers’ Forum II: Construction Materials
Event Location: London, UK
Event Dates: 19th February 2014
Date Deposited: 04 Jun 2015 08:42
Official URL: http://resolver.tudelft.nl/uuid:95faa6e6-bfa9-4f7b-8e25-de4a...
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