Nondestructive determination of chloride concentration using Ag|AgCl electrodes produced by electrochemical anodization

The stability of chloride ion selective electrodes in highly alkaline solutions is an important aspect when reliability and feasibility within reinforced concrete applications are concerned. The sensitivity of these electrodes largely depends on the properties of the AgCl layer, including uniformity, porosity, orientation, thickness, etc. These...

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

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...

Activated Carbon as a Pseudo-reference Electrode for Potentiometric Sensing Inside Concrete

The half-cell potential of the Activated carbon (AC), due to its high double layer capacitance (EDL), remains stable in high ionic electrolyte. The open circuit potential (OCV) of the AC, with EDL of 40 – 50 F, shows a stable potential (10 mV variation) over two weeks in the cement pore solution (sat. Ca(OH)2). The OCV is less sensitive to the...

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

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...

The importance of chloride sensors stability in monitoring ageing phenomena in concrete structures: Ag/AgCl electrodes performance in simulated pore-water environment

One of the reported problems associated with the performance of Ag/AgCl electrodes in alkaline environment, as concrete pore water, has been their poor stability. Open circuit potentials are typically observed to be stable for a time period of a few minutes to some days depending on the thickness and microstructure of the sparingly soluble AgCl...

Activated Carbon as a Pseudo-reference Electrode for Potentiometric Sensing Inside Concrete

The half-cell potential of the Activated carbon (AC), due to its high double layer capacitance (EDL), remains stable in high ionic electrolyte. The open circuit potential (OCV) of the AC, with EDL of 40 – 50 F, shows a stable potential (10 mV variation) over two weeks in the cement pore solution (sat. Ca(OH)2). The OCV is less sensitive to the...

Potentiometric response of chloride sensors in cementitious materials of varying chemical composition and water-to-cement ratio

Free chloride ions are the main cause of steel corrosion in reinforced concrete structures. Ag/AgCl electrodes, as chloride sensors, are predominantly sensitive to chloride ions and respond electrochemically to the chloride ion activity in the environment. This is reflected by changes of the open circuit potential (OCP) of the sensors. To...

Polarization Behaviour of Silver in Model Solutions

When studying chloride-induced corrosion in reinforced concrete structures, essential information of interest is the concentration of chloride ions in the system. The absence of a reliable method for monitoring the free chloride ions justifies the attempts towards establishing a feasible practice in the application of the already known Ag/AgCl...

Determination of Chloride Content in Cementitious Materials: From Fundamental Aspects to Application of Ag/AgCl Chloride Sensors

This paper reports on the advantages and drawbacks of available test methods for the determination of chloride content in cementitious materials in general, and the application of Ag/AgCl chloride sensors in particular. The main factors that affect the reliability of a chloride sensor are presented. The thermodynamic behaviour of silver in the...

Potentiometric response of Ag/AgCl sensor in Portland and slag cement pastes

Determination of the free chloride content in a concrete structure is important for evaluation of the risk of corrosion of reinforcing steel. The Ag/AgCl sensor is sensitive to chloride ions and exhibits an open circuit potential (OCP) that depends on the chloride ions activity in the environment. The interference of hydroxide and sulfide ions...

Microstructure, surface chemistry and electrochemical response of Ag|AgCl sensors in alkaline media

Characterization of the Ag/AgCl electrode is a necessary step toward its<br/>application as a chloride sensor in a highly alkaline medium, such as concrete.<br/>The nucleation and growth of AgCl on Ag in 0.1 M HCl was verified through<br/>cyclic voltammetry. Ag anodization was performed at current densities, determined<br/>by potentiodynamic...

Potentiometric Response of Ag/AgCl Chloride Sensors in Model Alkaline Medium

The stability and reproducibility of an Ag/AgCl sensors’ response in an alkaline medium are important for the application of these sensors in cementitious materials. The sensors’ response, or their open circuit potential (OCP), reflects a dynamic equilibrium at the sensor/environment interface. The OCP response in an alkaline medium is affected...

The application of Ag/AgCl electrodes as chloride sensors in cementitious materials

Determination of the chloride content in a reinforced concrete structure is important for evaluation of the risk of chloride-induced corrosion of reinforcement. The traditional techniques for chloride determination in concrete are laborious, time-consuming and cannot be used for continuous monitoring of the chloride content. The investigation on...

Determination of chloride content in cement-based materials: Comparison of results derived by conventional methods and chloride sensor readings

In this paper the potentiometric response of a Ag/AgCl electrode as a chloride sensor in cementitious materials of different mix design was studied. The chloride sensor’s response was discussed with respect to the presence of hydration products around the sensor. The free chloride content inferred from the sensor’s response was compared to the...