The development of cost-effective methods to mitigate rebar corrosion in existing chloride-contaminated bridge decks is a key research objective of many asset owners, including the Ministry of Transportation, Ontario (MTO). Such methods and technologies are vital to asset owners for the management of ageing transportation infrastructure. One such method is the use of distributed galvanic anode systems to provide cathodic protection to reinforced concrete.

A distributed galvanic anode system was installed in the bridge deck of MTO’s North Otter Creek Bridge on Highway 9 near Walkerton, Ontario in 2003. The performance of this system has been monitored regularly since its installation through direct readings of the system’s polarization and current density. MTO has also installed distributed galvanic anode systems in existing abutments as part of rapid superstructure replacement projects in Ottawa; the first was installed in 2007. Distributed galvanic anode systems have also been used in pier jackets and other bridge deck overlays. The monitoring data collected to date shows effective continuing corrosion protection.

This paper will first discuss the process of rebar corrosion in a bridge deck, then introduce the distributed galvanic anode system. This paper will then detail the anode monitoring data that has been collected and an analysis of the performance and ageing of distributed galvanic anodes in a number of MTO applications. Finally, this paper will present a case study of the design and installation of a distributed galvanic anode system for the King Street Overpass on Highway 401 in Cambridge, Ontario.