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.