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Iowa State University--Becoming the Best

Long Term Performance of Overlays: Thin Epoxy Overlay vs. Traditional Rigid Overlay


Principal investigators:

Co-principal investigators:

Project status

In progress

Start date: 08/01/17
End date: 07/31/18



About the research


Improving long-term bridge performance through better design and maintenance practices is an essential component in effectively managing our transportation assets. Demonstrating the integration of the Second Strategic Highway Research Program (SHRP2) R19A Service Life Design (SLD) recommendations on a fleet of bridge preservation projects is a part of the efforts aimed at promoting SLD concepts.

The Iowa Department of Transportation (DOT) has completed two of these projects, which include the use of A1010 steel in multiple girder lines of a newly constructed bridge and an extensive evaluation of concrete mixes to identify best practices that align with improving deck performance for SLD on another bridge. For this project, the Iowa DOT is proposing to integrate the recommendations from the R19A SLD guide into future bridge preservation. To be more specific, the performance of thin epoxy overlays will be evaluated and compared with the performance of low slump dense concrete (LSDC) overlays.

The objectives of this project are as follows: 1) evaluate the bond strengths of two types of overlays (i.e., thin epoxy overlay and LSDC overlay) and investigate the change in bond strength over time with on-site testing, 2) understand the long-term performance of epoxy overlays and rigid overlays via accelerated lab testing, 3) investigate how existing chloride that has been sealed in a deck by an epoxy overlay migrates and how that might relate or contribute to additional deck deterioration, 4) identify factors that affect the initial and long-term performance of overlays, and 5) estimate the expected service life for these two types of overlays.