Frank Papworth, Specialist Repair & Construction Products
Cathodic protection (CP) offers the advantage of permanent repair that does not require the expensive break out of sound but chloride contaminated concrete. Current is passed between an anode and the reinforcement, the reinforcement becomes cathodic and corrosion is halted, even if there are high levels of chlorides at the bar.
Although recognised as providing the ultimate corrosion protection impressed current CP (ICCP) may, in some circumstances be expensive to design, install and maintain. Michael Moore of Road and Marine Services (RMS) has been trialling a range of sacrificial anode CP (SACP) systems that have the potential to provide low cost, low maintenance holding repairs. If ICCP systems were all that was available Mr. Moore believes it would be difficult to provide the required maintenance in NSW bridges within budgetary constraints. Unfortunately there are reservations about sacrificial systems as historically zinc anodes have passivated and CP Standard criteria for potential decays have not been met. Three new innovative systems available in Australia are changing how people perceive ICCP and SACP.