Non-destructive evaluation of chloride-induced corrosion in reinforced concrete: Electrochemical impedance spectroscopy sheds new light on generally applied sensors performance

Farhad Pargar, Dessi Koleva, Eddie Koenders, Klaas van Breugel

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

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Abstract

Service life of reinforced concrete structures exposed to chloride enriched environment is well known to be mainly determined by steel passivity breakdown in the event of chloride-induced corrosion initiation and propagation. Since Cl- induced (localized) corrosion is caused by the free (water-soluble) chloride, present in the pore network of a reinforced concrete structure, quantifying the level of free chloride locally, e.g. via embedded Ag/AgCl electrodes (chloride sensors), is a generally accepted and applicable approach to monitor the time to corrosion initiation. The measurement is essentially a potential (voltage) reading over time and as such logically depends, among other factors, on the electrical and microstructural properties of the surrounding medium. Therefore, an accurate determination of the time to corrosion initiation significantly depends on the properties of relevant interfaces, such as the steel|cement paste interface and/or the Ag|AgCl|cement paste interface. In this paper, steel rods were coupled with Ag/AgCl sensors and embedded in cement paste cylinders. The specimens were immersed in simulated pore solution, containing 855 mM chloride concentration. Electrochemical impedance spectroscopy (EIS) was employed for quali-/quantification of the corrosion process on the steel surface (medium to low frequency response), while simultaneously providing information for the electrical properties of the bulk cement-based matrix through the high frequency response. The open circuit potential (OCP) values of both sensors and steel rods were recorded for more than 30 days. The results show a good agreement between sensor readings and steel electrochemical response i.e. time to corrosion initiation was recorded via steel OCP readings, whereas the relevant chloride content was estimated via the sensors’ OCP readings.
Original languageEnglish
Title of host publication6WCSCM, Barcelona, Spain
Number of pages7
Publication statusPublished - 2014
Event6th edition of the World Conference of the International Association for Structural Control and Monitoring - Edificio Vèrtex, Universitat Politècnica de Catalunya, Barcelona, Spain
Duration: 15 Jul 201417 Jul 2014
Conference number: 6
http://www.6wcscm.es/

Conference

Conference6th edition of the World Conference of the International Association for Structural Control and Monitoring
Abbreviated title6WCSCM
CountrySpain
CityBarcelona
Period15/07/1417/07/14
Internet address

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