Experimental Evaluation of Bonding between CFRP Laminates and Different Structural Materials

Abstract

This study presents an analysis of carbon fiber reinforced polymers (CFRP)-to-parent material interfaces based on 40 single-lap shear tests intended to highlight the strength of the interfaces under fracture mode II. Three different substrates are analyzed: timber; concrete, and steel, using the same CFRP laminates and adhesive agent. The externally bonded reinforcement (EBR) technique was used throughout the study. The results show that the CFRP-to-timber interfaces had the highest strength but also showed that these interfaces need a longer bonded length in order to reach maximum strength, i.e., CFRP-to-timber interfaces had the longest effective bond length. The local nonlinear bond-slip curve of CFRP-to-concrete can be approximated to exponential curves, whereas the CFRP-to-timber or steel interfaces showed trilinear and bilinear bond-slip relations, respectively. Also, the CFRP-to-timber interfaces revealed the highest fracture energy.