NCHRP Project 10-37, Performance of Epoxy-Coated Reinforcing Steel in Highway Bridges, and major studies conducted by the Federal Highway Administration (FHWA), the Canadian Strategic Highway Research Program (CSHRP), and the Concrete Reinforcing Steel Institute (CRSI), have examined past and current practices on the use of epoxy coatings to prevent corrosion of reinforcing steel. These studies, coupled with the experiences of state highway agencies, indicate a potential for less service life than previously expected and, consequently, the premature need for rehabilitation. Also, epoxy-coated reinforced concrete bridges will need to be rehabilitated because of deterioration caused by a number of other factors in addition to the corrosion of reinforcing steel. State departments of transportation and other users of epoxy-coated reinforcing steel in structures, particularly those structures subjected to chlorides from deicing salts or marine environments, need to be prepared to repair and rehabilitate these structures.
The presence of epoxy-coated reinforcement will require repair and rehabilitation strategies different from those used on bridge components with uncoated reinforcing steel. Research conducted to date has involved the application of cathodic protection techniques to arrest deterioration; however, other techniques and factors involved in repair and rehabilitation should be examined. Factors, such as the quality of the coating, the extent to which the coating must be removed, cleanliness of the bar, and the electrochemical properties, must be addressed. It is therefore necessary to identify suitable repair and rehabilitation techniques and the conditions under which they should be used.
The objective of this research is to identify short-, medium-, and long-term strategies for repair and rehabilitation of distressed concrete bridge components containing epoxy-coated reinforcing steel. Although distress may result from a number of causes, and strategies shall address all situations, it is expected that the major emphasis will be placed on distress caused by corrosion of reinforcing steel. The advantages and limitations of strategies, including the optimum time of intervention, will be listed, and validation testing will be conducted. The final product will be a decision matrix that defines repair and rehabilitation strategies as a function of the component, the condition of the component, and the life expectancy of the technique.
Research will be accomplished by conducting, as a minimum, the following tasks: (1) Identify and assess possible repair and rehabilitation strategies for reinforced concrete bridge components containing epoxy-coated reinforcing steel. It is expected that the repair and rehabilitation strategies will include, but not be limited to, the following: patches, overlays, corrosion inhibitors, electrochemical techniques, barrier techniques (e.g., sealers, coatings, membranes), partial replacement, and the do-nothing option. New strategies--previously untried or applied on a limited basis--shall not be overlooked. Recommend strategies for repair and rehabilitation of concrete bridge components with epoxy-coated reinforcing steel. Describe those strategies that may be suitable without additional investigation and those that will require further evaluation or validation for use on components with epoxy-coated reinforcing steel. (2) Prepare an interim report summarizing the results of Task 1 and containing an updated work plan for those repair and rehabilitation strategies recommended for evaluation or validation. The work plan to be executed in Task 3 should include the strategies to be investigated, the rationale, the details of test procedures, and the proposed method of analysis. (The interim report will be due 4 months after contract initiation. NCHRP approval will be required before proceeding with subsequent tasks.) (3) Conduct investigations to determine the capabilities and limitations of the techniques and conditions for use. It is expected that this task will generate information on materials, procedures, type of component, and condition of component at time of intervention. Laboratory and/or field investigations are anticipated. (4) Develop the decision matrix as described in the objective paragraph. While it is not expected that specifications for the repair and rehabilitation strategies will be prepared, it is required that key activities in each technique will be identified and sufficiently described. (5) Submit a final report that includes an implementation plan for moving the results of this research into practice.
: Research is complete. The agency's final report documents the entire research effort and, of particular interest, includes the Task 4 decision matrix.
The agency's revised final report is available online as NCHRP Web Document 50