U.S. Department of Transportation
Federal Highway Administration
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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
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Publication Number: FHWA-HRT-07-043
Date: July 2007
Chapter 1. Introduction
Epoxy-coated reinforcement has been in use for more than 30 years and, when used in conjunction with increased concrete cover, has provided significant improvements over uncoated bars in the corrosion performance of reinforcing steel.(1,2) The system, however, has not been without its problems or critics.(3,4) Problems include the poor performance of epoxy-coated reinforcement when the concrete remains saturated, such as occurs in bridge piers in the salt water(4) and the observation that, with time, the epoxy tends to lose its adhesion to steel. (See references 1, 4, 5, 6, and 7). The loss of adhesion is accelerated when the concrete remains wet.
In spite of the problems and the observation that portions of epoxy-coated reinforcement rusts, this rust has not resulted in the need for repairs when used in structures, such as bridge decks, that allow the concrete occasionally to dry.(1,2) Because epoxy-coated reinforcement is a good, but not perfect, corrosion protection system, there is strong impetus to develop methods that improve its performance.
With this in mind, the objective of this research is to evaluate a number of techniques for making epoxy-coated reinforcement (ECR) more corrosion resistant by using multiple corrosion protection strategies for ECR in bridge decks, as well as for bridge members in a marine environment where abundant salt, moisture, and high temperatures (tropical weather) are prevalent.
This interim report describes the results of ongoing tests of systems that include chemical pretreatments and epoxy formulations that increase the adhesion of the epoxy coating, conventional epoxy-coated reinforcement used in conjunction with inorganic and organic corrosion inhibitors, and bars that are initially coated with zinc prior to epoxy application.
The details of the study are presented in the following chapters.