Ontario Ministry of Transportation and Vector Corrosion Technologies Investigate Galvanic Cathodic Protection Systems for Concrete Bridge Deck Overlays
March 04

Over the past three and a half years, Vector Corrosion Technologies has been working with the Ontario Ministry of Transportation (MTO) to develop an innovative galvanic protection system that can be used to provide cathodic protection for chloride contaminated bridge decks.

Galvanic systems can be used to provide cathodic protection to the embedded reinforcing steel if the system provides a sufficient level of current. Typical systems that are currently used to achieve galvanic cathodic protection on bridges and other structures include activated zinc metalizing for substructures and other non-traffic bearing surfaces and galvanic jackets (zinc anodes inside an FRP jacket) for columns and piles.

In November 2001, the Ontario Ministry of Transportation wished to evaluate galvanic anodes for protecting chloride contaminated bridge decks underneath a concrete overlay. Galvanic cathodic protection systems have the potential to provide effective corrosion protection for concrete structures, while reducing the operating cost associated with monitoring and maintaining impressed current cathodic protection (ICCP) systems used in bridge deck overlays. By providing cathodic protection to the original parent concrete which is chloride contaminated, the service life of the bridge deck would be significantly enhanced.

To test the concept, various galvanic cathodic protection systems were installed on 40 year old chloride contaminated concrete bridge deck slabs. The current output of the galvanic anodes were monitored and depolarization tests were completed at various times. Depolarization testing has indicated that the level of polarization varies over time but has consistently exceeded the National Association of Corrosion Engineers 100 mV polarization criteria.

Based on the performance of the galvanically protected bridge deck slabs, MTO proceeded with field installation in a bridge deck overlay in September 2003. This galvanic system was similar to the trial above but was prefabricated to facilitate field installation and quality control.

Blanket protection was provided by distributed galvanic anodes that were embedded into the new concrete overlay. The distributed anodes were bonded to the prepared surface with a low resistance mortar to ensure a conductive path existed between the galvanic anode and the base concrete bridge deck. The anodes were interconnected on the surface and connected to the reinforcing steel. Before the new concrete was placed, a carbon fiber mesh was installed over the anodes to minimize the potential for overlay cracking. Data from this field site is showing that the system continues to provide galvanic cathodic protection.

Details regarding the MTO research program were published in the February, 2004 issue of MTO Road Talk. In this publication, MTO states that based on this testing "...sacrificial anode systems may eventually replace impressed current systems as the standard for cathodic protection..."

For additional information regarding galvanic cathodic protection, please contact Vector Corrosion Technologies.

	Vector Introduces Galvashield XP+, 2nd Generation Discrete Galvanic Anode
	Vector Introduces Galvanode™ ASZ+ Activated Arc Spray Zinc
	Norcure® ECE and Galvashield XP protects I-480, as Published in Bridge Builder
	Corrosion Management Systems for Concrete, as Published in Concrete International
	FDR Drive Rehabilitation Selected New York Construction Project of the Year
	Reagan National Airport Selects Norcure® Re-alkalization and Chloride Extraction
	I-480 Bridge Repair Project Receives ICRI Award
	Vector Corrosion Technologies Receives Sustainable Development Award