Laboratory experiments established that corrosion of steel reinforcement can be arrested within relatively short periods if a sufficient cathodic current density higher than 20 mA/m2 is applied. After corrosion is arrested, it is only necessary to maintain steel passivity longer-term by cathodic prevention, a process that requires a much-reduced current density. Once the two-stage principle was tested and established in the laboratory, self-contained anodes were developed, each product comprising a battery-operated Impressed Current Cathodic Protection element and a galvanic anode component. A high initial current output substantially above 20 mA/m2 by area of steel is delivered over a period of weeks during which corrosion arrest is achieved. The galvanic anode components then deliver the lower cathodic prevention current long-term. This paper introduces the concept and principles of the technique, illustrates products developed and presents medium-term field studies to demonstrate the success of the Two-Stage CP technique.

Subject
Depolarization, Steel reinforcement, Corrosion prevention, Galvanic anodes, Impressed current cathodic protection, Cathodic protection, Corrosion currents, Constants, Cathodic current density, Steel, Galvanic current, Chlorides, Anodes
Keywords:
Galvanic anodes, Cathodic Protection, Corrosion control, Steel reinforcement
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2023
Association for Materials Protection and Performance (AMPP)
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