Influence of Elevated Temperatures on the Bond Between CFRP Strips and Concrete Using the NSM Technique - Definition of Local Bond vs. Slip Laws

Azevedo A. S., Firmo J. P., Correia J. R., Tiago C.

10th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering (CICE), İstanbul, Turkey, 8 - 10 December 2021, vol.198, pp.300-311 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 198
  • Doi Number: 10.1007/978-3-030-88166-5_25
  • City: İstanbul
  • Country: Turkey
  • Page Numbers: pp.300-311
  • Keywords: CFRP strips, NSM strengthening technique, Concrete-CFRP bond, High temperatures, Experimental study, Bond vs. slip laws
  • Istanbul Technical University Affiliated: No


This paper presents experimental and numerical investigations about the effects of elevated temperatures on the bond behaviour between concrete and carbon fibre reinforced polymer (CFRP) strips installed according to the near-surface mounted (NSM) technique. Firstly, single-lap shear tests were performed on concrete prisms strengthened with CFRP strips inserted into slits pre-cut in the concrete cover and bonded with an epoxy-based adhesive. The specimens were heated up to the target temperature (from 20 to 270 degrees C, measured in the adhesive) and then loaded up to failure while the temperature was maintained constant. The experimental results show that with increasing temperatures (i) the bond strength is significantly reduced, and (ii) the failure mode changes from CFRP tensile failure at 20 degrees C and 50 degrees C to adhesive failure in the CFRP-adhesive interface at higher temperatures. Secondly, a numerical procedure was developed to calibrate (based on the experimental results) the local bond vs. slip laws at different elevated temperatures. Overall, both the stiffness and maximum bond stress of the obtained laws decrease with increasing temperatures; in addition, the predicted load vs. slip curves fit well the experimental counterparts.