Cathodic protection of bridge decks: a study of three Ontario bridges

Many concrete bridge decks are being damaged by surface spalling or internal delaminations caused by corrosion of the reinforcing steel. Cathodic protection can be applied to bridge decks to stop this type of damage. Cathodic protection was applied to three bridge decks in Ontario: two slab decks on AASHTO beams and a voided, posttensioned structure. Each deck was equipped with resistance probes, which showed that the corrosion of the reinforcing steel was stopped when cathodic protection was applied. The bridges were studied to determine the minimum potential required and the most advantageous electrode configuration and spacing for adequate protection. The technique for measuring the polarized potential on the steel was studied, and probes buried in the conductive layer were found to be more effective than half-cell measurements. Data for all three bridges are presented. The protection on the first two of these bridges has been operated successfully for 1 year, and that on the third bridge has been operated successfully for 9 months.