A New Corrosion Sensor to Determine the Start and Development of Embedded Rebar Corrosion Process at Coastal Concrete

Abstract

The corrosion of reinforcements induced by chloride has resulted to be one of the most frequent causes of their premature damage. Most corrosion sensors were designed to monitor corrosion state in concrete, such as Anode-Ladder-System and Corrowatch System, which are widely used to monitor chloride ingress in marine concrete. However, the monitoring principle of these corrosion sensors is based on the macro-cell test method, so erroneous information may be obtained, especially from concrete under drying or saturated conditions due to concrete resistance taking control in macro-cell corrosion. In this paper, a fast weak polarization method to test corrosion state of reinforcements based on electrochemical polarization dynamics was proposed. Furthermore, a new corrosion sensor for monitoring the corrosion state of concrete cover was developed based on the proposed test method. The sensor was tested in cement mortar, with dry-wet cycle tests to accelerate the chloride ingress rate. The results show that the corrosion sensor can effectively monitor chloride penetration into concrete with little influence of the relative humidity in the concrete. With a reasonable corrosion sensor electrode arrangement, it seems the Ohm-drop effect measured by EIS can be ignored, which makes the tested electrochemical parameters more accurate.

Electrochemical Sensors for Monitoring the Corrosion Conditions of Reinforced Concrete Structures: A Review

“…The main conclusion from this study was that the experience with monitoring systems has increased significantly [96]. In the same year Xu et al [97] published a manuscript proposing a fast weak polarization method to test the corrosion state of reinforcements based on electrochemical polarization dynamics. Additionally, the authors developed a new corrosion sensor to monitor the corrosion state of concrete cover based on the proposed method.…”

“…Additionally, the authors developed a new corrosion sensor to monitor the corrosion state of concrete cover based on the proposed method. The authors concluded that the corrosion sensor effectively monitored the chloride penetration into concrete with insignificant influence of the relative humidity in the concrete [97].…”

Determination of pH in Powdered Concrete Samples or in Suspension

“…The measuring system was composed of a white light source, a camera, and two optical filters. More accurate measurement of pH values in concrete have been achieved by various methods including: (a) a flat-surface electrode system in combination with filter paper [15], (b) a sensor based on a three-electrode electrochemical test [16] and (c) Ag/Ag 2 O sensors manufactured using a screen-printing process, which demonstrated good response time and reproducibility [17]. Further, a technique for measuring the free chloride concentration and pH value of mortar specimens was reported in [18] based on several Ag/AgCl ion-selective and iridium/iridium oxide electrodes.…”

Simulation of Real Defect Geometry and Its Detection Using Passive Magnetic Inspection (PMI) Method

“…Each NDT method has limitations [23]; for instance, the macro-current measurement is complicated to interpret, since its results are influenced by the distance between anode and cathode and humidity [24]. GPR results are influenced by the existence of voids and variable internal moisture conditions [25], which can confound interpretations in many ways, such as confusion with background structures, shadowing, or false identification of gaps or previously repaired sites as being corrosion sites (Type I errors) [4].…”