INVESTIGATION OF THE RESPONSE OF INTERFACES OF CFRP SHEET STRENGTHENING SCHEMES ENHANCED WITH TOUGHENED EPOXY ADHESIVE LAYERS APPLIED IN CORRODED CONCRETE SUBSTRATES.

This paper studies the behavior of enhanced strengthening Carbon Fiber Reinforced Polymer (CFRP) strengthening schemes. The CFRP systems are bonded to concrete substrates using toughened adhesive layers to limit the failure propagation in the interface and its brittle nature. Due to the importance of the integrity of the substrate two different scenarios are examined experimentally and analytically: healthy concrete and with corrosion products leached by the corroded reinforcement. The modified shear behavior (stress, slip) of the interfaces between concrete and CFRPs was investigated with a double shear test configuration. The corrosion products leached on the external layers of the substrate affected the interface response of the strengthening scheme, resulting in lower rates of shear stresses corresponding to lower slip ratios. The analysis of the sliding and shear stress distribution along the interface has also been investigated locally by finite elements using a cohesive model (CM) to examine the propagation of failure at the interface length. Toughened adhesives limit the substrate’s dislocations and shift the response of the interface from pure elastic to pseudo-ductile in distinct stages. The debonding mode (brittle or pseudo-ductile) depends heavily on the toughness of the adhesive and its tensile modulus, since the higher the modulus is, the more brittle the response becomes