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

Abstract

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 presence or absence of chloride ions is described and kinetic restrictions are addressed. The parameters that can affect the activity of chloride ions in the medium and/or the rate of ion exchange and dissolution/precipitation processes at the sensor’s surface are also considered. In this regard, the contribution of morphology and microstructure of the AgCl layer, binding of chloride ions and the compactness of hydration products around the chloride sensor are highlighted. The important parameters for a reliable sensor’s response are discussed and the possible causes of inaccuracies are evaluated.

Facial Fabrication and Characterization of Novel Ag/AgCl Chloride Ion Sensor Based on Gel-Type Electrolyte

“…When no kinetic restrictions are applied, the dynamic equilibrium between metallic silver (Ag 0 ) and Ag + can be established in a short duration. This feature makes the noble Ag metal prone to “corrosion” in environments with aggressive ions such as Cl − (Pargar et al, 2017 ). As shown in Figure 9C , a good linear fit curve is obtained, and the correlation coefficient ( R 2 ) of the Cl − sensor is 0.9712.…”

Application of Ag/AgCl Sensor for Chloride Monitoring of Mortar under Dry-Wet Cycles

“…In addition, Ag/AgCl electrode has the advantages of small temperature coefficient and good reversibility. In general, the common Ag/AgCl chloride electrode is a solid-state membrane electrode that consists of an Ag core with a coating layer of AgCl [14][15][16][17][18]. For the formation of Sensors 2020, 20, 1394 3 of 14…”

“…Compared with ALS, it demonstrates that Ag/AgCl electrodes are more sensitive to chloride. The research provides the key element for the specific application of Ag/AgCl electrode for corrosion monitoring in the future.outer AgCl layer, there are several commonly manufactured methods such as powder pressing, sintering [11,19], chlorination and DC current polarization [20].With regard to application of Ag/AgCl, it has been used as the reference electrode for many purposes [15,20,21] and in recent decades has began to be studied in its use as chloride sensor in the concrete industry [17,22,23]. Relative attempts to embed Ag/AgCl electrodes into cement-based materials were gradually reported since the 1990s [24][25][26][27].…”

“…With regard to application of Ag/AgCl, it has been used as the reference electrode for many purposes [15,20,21] and in recent decades has began to be studied in its use as chloride sensor in the concrete industry [17,22,23]. Relative attempts to embed Ag/AgCl electrodes into cement-based materials were gradually reported since the 1990s [24][25][26][27].…”

Developing a Multi-Element Sensor to Non-Destructively Monitor Several Fundamental Parameters Related to Concrete Durability

“…However, most of them were limited to be used in the laboratory and unable to provide accurate information about the free Cl − (Cl f ) content in pore solution of concrete. Compared to other techniques, the potentiometric technique such as Ag/AgCl sensor is more appropriate conduct non-destructive and in-situ measurement of Cl f concentration due to these advantages such as accuracy and simplicity [ 23 ]. As early as the 1990s, Atkins et al [ 24 ] and Climent-Llorca et al [ 25 ] reported using the Ag/AgCl sensor to detect the Cl f concentration in simulated pore solution and mortar specimens.…”