A durability study of externally bonded FRP-concrete beams via full-field infrared thermography (IRT) and quasi-static shear test

Durability of 36nos. externally-bonded CFRP-concrete beams was studied by monitoring the intermediate cracking (IC) processes using infrared thermography (IRT) and quasi-static direct shear test. Specimens were exposed to three elevated water temperatures (25 °C, 40 °C and 60 °C) for 5, 15 and 30 weeks. In addition to the measurement of the properties at ultimate state, this work attempts to characterize the intermediate states of the intact, softened and ruptured part during the IC debonding process. The results show that the adhesive bond layers of the 40 °C and 60 °C specimens were ruptured and softened at a force level much lower than that for the 25 °C and control specimens. This is explained by the exposure condition that the water temperature exceeded the heat distortion temperature of the adhesive layer, which accelerated the bond deterioration of the composites.