Minnesota Department of Transportation

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Anchorage of epoxy-coated rebar using chemical adhesives

Status:  Complete
Report Date:  02/15/2019

Summary:

As bridges age, local and state agencies are called on to repair and upgrade elements. Local agencies may install new light posts and replace chain-link rails, while state agencies may replace slabs on wing walls, deck and crash barriers, and other non-hanging bridge components. Work like this requires replacing concrete elements and installing new reinforcement bars. Until recently, MnDOT and local agencies used epoxy-coated steel rebar for these post-installed concrete panels and barriers. A survey of state transportation agencies found that many use chemical adhesives to post-install epoxy-coated rebar in hardened concrete, a practice that MnDOT has suspended. Laboratory testing showed that the practice works well and provides a safety level 200 to 300 times that predicted by manufacturer specifications. Performance varied by about 10 percent among the different adhesives and with epoxy-coated versus uncoated rebar. Researchers recommended modifications to the process that would allow MnDOT to resume using coated rebar in post-installed concrete crash barriers.

Final Deliverables:

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