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Assessment of Epoxy Coating on Bridge Deck Reinforcement

In the early 1970s, when the U.S. Interstate Highway System was being built, premature deterioration of reinforced concrete bridge decks in the northern portions of the U.S. became evident. The cause was identified as chloride-induced corrosion of the reinforcing steel from deicing salt applications. Techniques used to decrease the rate of deterioration of bridge decks included increasing the clear concrete cover depth, reducing the permeability of the concrete, and improving the deck surface drainage characteristics. Further extension of the initial service life and time to overlaying was sought through development of epoxy-coated reinforcement (ECR). The effectiveness of ECR has been questioned, with field studies reporting service life extensions ranging from 1 to 82 years. In this article, the authors summarize a portion of their study of core specimens taken from existing bridge decks and subjected to accelerated testing in the lab. Drilled core specimens were taken from 10 bridge decks in Virginia, with 28 cores containing uncoated reinforcement (UCR) taken from 2 decks and 113 cores containing ECR taken from 8 decks. Using a dry saw, the top surface of each specimen was removed to yield a top cover of 13 mm. The authors then verified that chlorides has not penetrated the concrete to the depth of the newly exposed top surface. The accelerated testing program comprised cyclic ponding with 3% NaCl solution for 2 days, followed by 5 days of drying under lab conditions. Ponding continued for 3 years or until a specimen cracked. From early in the study, percentages of specimens exhibiting bar corrosion or cracking of the cover concrete were much lower for those containing ECR than for those containing UCR. Even so, corrosion initiated in a few of the ECR specimens before corrosion initiated in any of the UCR specimens. Corrosion initiated in all of the UCR specimens in less than 1 year, and the cover concrete cracked on all of the UCR specimens in about 2 years. At the end of the 3-yr study period, corrosion had initiated in 70% of the ECR specimens, and cracking of the cover concrete had occurred in about 25% of the ECR specimens. Although the concrete cover was only 13 mm, and chloride penetration into the concrete was accelerated through weekly ponding cycles, the results clearly demonstrate the variability of corrosion protection provided by ECR.

  • Availability:
  • Authors:
    • Weyers, Richard E
    • Brown, Michael Carey
    • Sprinkel, Michael M
  • Publication Date: 2008-6

Language

  • English

Media Info

  • Media Type: Print
  • Features: Figures; Photos; References; Tables;
  • Pagination: pp 55-60
  • Serial:
    • Concrete International
    • Volume: 30
    • Issue Number: 6
    • Publisher: American Concrete Institute (ACI)
    • ISSN: 0162-4075

Subject/Index Terms

Filing Info

  • Accession Number: 01103607
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jun 25 2008 9:25AM