Demonstration Project No. 34, Cathodic Protection for Reinforced Concrete Bridge Decks, Woodinville Interchange Bridge No. 522/30 ES

Under FHWA Demonstration Project No. 34, "Cathodic Protection for Reinforced Concrete Bridge Decks," a slotted cathodic protection system was installed on the ES ramp in the Woodinville Interchange during the summer of 1985. The slotted cathodic protection system involves sawing 3/4" slots longitudinally in the existing deck at one-foot centers. Platinum wire or carbon strand wire is placed in the cut slots first and then conductive polymer is filled in the slots. Electric power from a rectifier supplies current to the wire and conductive polymer. The current then flows to the top mat reinforcing steel, giving the steel protection from further corrosion.

The objective of the demonstration project was to familiarize the Washington State DOT with this new technology. This objective was fulfilled.

Some problem areas with the system were identified during the work:

  1. A more positive method of finding grounding locations from the anode to rebar nicks, ties, etc. needs to be developed. Perhaps an instrument can be used to supplement visual inspection.
  2. The necessity for having a minimum of 1/2-inch cover from the bottom of the slot to the top of the rebar needs to be resolved.
  3. A better method of installing the conductive polymer needs to be developed. Hand-spreading of the material from plastic bags results in sloppy work.
  4. Procurement time for the rectifier needs to be shortened.
  5. Since the project, once it has started, moves along very rapidly, there is very little time for on-the-job training of workers. Workmen should have prior experience at this work.
  6. In remote areas, sources of electrical power may not be available. It will be necessary for sources of power, such as solar panels or long-lasting batteries to be developed for this system.

These problems need to be overcome to obtain a better quality product. 

Publication Date: 
Thursday, April 3, 1986
Publication Number: 
WA-RD 087.1
Last modified: 
10/12/2016 - 15:41
Tom H. Roper, Edward H. Henley.
Washington (State). Dept. of Transportation. Bridge and Structures Branch.
Number of Pages: 
Anodes, Bridge decks, Building, Cathodic protection, Concrete, Corrosion protection, Demonstration projects, Electrical conductivity, Facilities, Installation, Polymers, Reinforced concrete, Wire.