Evaluating FRP/Concrete Bond Using Infrared Thermography

Damaged concrete structures are often reinforced with fiber-reinforced polymer (FRP) composites. Although FRP composites are known to greatly increase the strength of these structures, enhancement is dependent upon the bond between the concrete and the FRP composite. The current method of evaluating that bond is known as the pull-off test in which a circle is drilled through the FRP and concrete, a steel disk is then affixed to the FRP composite and pulled off. The layer that fails is the weakest layer. If the bond is correct the test will fail in the concrete. This test is very destructive and only tests the one circular section; infrared thermal imaging can test the entire area and is not harmful to the test specimen. This research focused on using infrared thermal imaging in conjunction with the pull-off test to better evaluate the bond and prove the legitimacy of thermal imaging. Twenty-four small concrete blocks were built, FRP was applied, images were taken and processed, and 104 holes were drilled and are ready to be tested in the fall. Results will come shortly