Abstract
Steel corrosion is the most common reason for the premature deterioration of reinforced concrete structures. Consequently, cathodic protection of steel in concrete has been substantially developed during the past two decades. In particular, galvanic protection consists in generating a natural macrocell corrosion system in which a sacrificial metallic anode (zinc, typically) is involved to apply a cathodic polarization to the corroding steel layout, in order to mitigate or annihilate the corrosion kinetics. Whether the general principle of cathodic protection is not questionable, the global design process can be significantly improved by increasing the knowledge on electrochemical behaviours of the different components of the protecting system. Regarding zinc anodes in concrete, the literature is very scarce. The time evolution of such systems is also not rigorously addressed, aging effects are systematically ignored and zinc anodes are usually considered as non-polarizable and inert over time. In this paper, the polarization response of a zinc layer anode (ZLA) in concrete electrolyte and its time evolution are studied. The results show a rapid evolution of the ZLA behavior, once the protecting system is connected to steel reinforcements. Moreover, the characterization of ZLA provided relevant electrochemical properties for the numerical design of galvanic protection systems.
Highlights
IntroductionGalvanic protection of steel in concrete consists of generating a natural macrocell corrosion system in which a sacrificial metal (such as zinc) is involved as an anode to apply a cathodic polarization to the corroding reinforcing bars and mitigate or annihilate the corrosion kinetics
Galvanic protection of steel in concrete consists of generating a natural macrocell corrosion system in which a sacrificial metal is involved as an anode to apply a cathodic polarization to the corroding reinforcing bars and mitigate or annihilate the corrosion kinetics
The following discussion pays particular attention to the anodic behaviour of the zinc layer anode (ZLA), which is involved in the galvanic protection of steel in reinforced concrete
Summary
Galvanic protection of steel in concrete consists of generating a natural macrocell corrosion system in which a sacrificial metal (such as zinc) is involved as an anode to apply a cathodic polarization to the corroding reinforcing bars and mitigate or annihilate the corrosion kinetics. Due to the potential gradient between the zinc anode and the reinforcing steel bars, a macrocell current is generated in the concrete volume, corresponding to the so‐called galvanic protection current. This protection current is controlled by the electrical resistivity of the concrete. Abundant literature can be found regarding the experimental illustration of the mutual polarization between sacrificial anodes and the reinforcing steel to be protected [1,2,3,4], where the authors compare the performances of several galvanic anodes and developed protocols for laboratory and on‐site current monitoring
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