Anchorage of epoxy-coated rebar using chemical adhesives

Principal Investigator(s):

Ben Dymond, Assistant Professor, UMD-Civil Engineering

Project summary:

Post-installed reinforcement is used to connect a new concrete member to an existing concrete structure. Use of traditional black steel in post-installed applications may lead to corrosion. To this end, the Minnesota Department of Transportation (MnDOT) and local bridge owners have used and continue to use epoxy-coated rebar in anchorage applications with chemical adhesives (e.g., post-installed traffic barriers or pier crash struts). However, chemical adhesive suppliers (e.g., Red Head, Hilti, Powers, or ATC) have indicated that design tables specifying tensile pullout strength of rebar installed with a chemical adhesive were all developed using traditional black rebar. The objective of this project is to answer the following questions: a) What is the effect of the rebar epoxy coating on the tensile pullout strength when compared to traditional black rebar, where both types of bars are post-installed with the same chemical adhesives? b) Is the tensile pullout strength of epoxy-coated rebar greater or lesser than the tensile pullout strength of traditional black rebar? To achieve the project objectives, the researchers will conduct a laboratory study that involves casting and testing representative sample specimens that include both epoxy-coated rebar and traditional black rebar. The test setup and specimens will be built in accordance with ACI 355.4-11, entitled, "Qualification of Post-Installed Adhesive Anchors in Concrete," which references the test setup outlined in ASTM E488-15, entitled, "Standard Test Methods for Strength of Anchors in Concrete Elements." In each test specimen, the amount of applied load, displacement, and failure mechanism will be recorded.

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