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Replacing Thermal Sprayed Zinc Anodes on Cathodically Protected Steel Reinforced Bridges - UTC

Started: August, 2008 Ended: June, 2011 Project ID #4W2276 Status: Completed

Objective

The objectives of this project are to determine the most cost-effective method to remove existing zinc anodes from a concrete surface, and to develop a protocol to prepare the concrete surface for the new anode.

Abstract

Corrosion of reinforced concrete structures is a major and increasing problem worldwide. U.S. highway departments spend an estimated $5 billion each year to remediate chloride-induced rebar corrosion of concrete bridges. The Oregon Department of Transportation (ODOT) has historic reinforced concrete bridges along the coast that employ impressed current cathodic protection (CP) to greatly reduce the corrosion of the embedded steel reinforcement. The CP systems rely on passing an electric current into the concrete through zinc metal anodes that have been sprayed onto the surface of the concrete. Some of these zinc anodes are nearing the end of their design lives, while others are beginning to separate from the concrete prematurely. Anode sections that have debonded no longer protect the underlying steel reinforcement, and the natural rate of corrosion resumes. Currently, there is no procedure established by ODOT to remove old anodes, prepare the concrete surface, and install new anodes. Using both laboratory investigation (in the WTI Corrosion and Sustainable Infrastructure Laboratory at Montana State University) and field investigation (on an Oregon bridge), researchers will investigate various methods for each of these procedures. The main “product” expected from this research will be a final report that includes procedures and recommendations for old anode removal and surface preparation before new anode application, which can be incorporated into field specifications for CP systems.

Contacts

Files & Documents

Sponsors & Partners

  • Oregon Department of Transportation (ODOT) Sponsor
  • Research and Innovation Technology Administration (RITA) Co-Sponsor

Part of: Infrastructure Maintenance and Materials, Corrosion and Sustainable Infrastructure Laboratory

Project Tagged In: corrosion, reinforced concrete, cathodic protection

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