ABSTRACT
An overview is given of the application of cathodic protection to reinforced concrete structures in The Netherlands. Three cases of successful application of cathodic protection (CP) to concrete structures are described. One example (a large number of cantilever beams with mixed in chloride) shows the relative stability of the performance of a CP system with activated titanium strip anodes in cement-injected boreholes over 6 years. The second case with conductive coating on slabs and columns (with mixed in chloride) was successful for several years and a similar design has been adopted for more structures of the same type. In the third case, mild steel reinforcement was corroding in parts of a post-tensioned structure due to de-icing salt leakage in the joint. The reinforcement was cathodically protected with a one metre wide strip of conductive coating anode, without endangering the prestressing steel. During design, execution and monitoring of these and other projects, testing methods and evaluation procedures have been developed, which were adopted in a national Technical Recommendation. In all documented cases, CP has shown to be effective in preventing further corrosion damage. Long term monitoring of structures receiving CP has shown that significant scatter may be present in sets of depolarisation values. Drying out of the concrete (due to repairs and the application of a coating) causes the current to decrease, sometimes also reducing the depolarisation levels. Both effects pose difficulties for interpretation, which require further study.
