Influence of External Compressive Stresses on the Performance of GFRP-to-Concrete Interfaces Subjected to Aggressive Environments: An Experimental Analysis

Despite the fact that fiber reinforced polymer (FRP) composites are a reliable structural material with reasonable durability performance, the environment to which the strengthened structure is exposed can make the strengthening system vulnerable. In this study, the effectiveness of externally bonded reinforcement (EBR) systems when external compressive stresses are applied to glass fiber reinforced polymers (GFRP)-to-concrete interfaces in several aggressive environments is analyzed. The compressive stress imposed on the GFRP-to-concrete interface intends to simulate, for instance, the effect produced by a mechanical anchorage system applied to the EBR system. The design and the region to set those mechanical anchorage systems are not yet well understood and are mostly applied without really knowing how they will behave. This work shows an exhaustive experimental program based on several double shear tests subjected to salt fog cycles, dry/wet cycles and two distinct temperature cycles: from -10 degrees C to +30 degrees C and +7.5 degrees C to +47.5 degrees C. The Mohr-Coulomb failure criterion was found to provide a good representation of the performance of the GFRP-to-concrete interface, and changes of cohesion and the internal friction angle of those interfaces during the hours of exposure to the aggressive environments are reported.