The influence of temperature on RC beams strengthened with externally bonded CFRP reinforcement

Strengthening of Reinforced Concrete (RC) structures with externally bonded Fibre Reinforced Polymer (FRP) reinforcement has become increasingly popular in the construction industry last two decades. Failure of the FRP strengthening is generally initiated by debonding of the FRP reinforcement from the concrete surface. It is expected that temperature will affect this debonding behaviour due to the significant difference in the coefficient of thermal expansion between concrete and FRP and due to the change of the material properties at elevated temperatures, especially of the adhesive. This paper presents the results of an experimental investigation into the effect of temperature on the strengthening of reinforced concrete beams with externally bonded Carbon Fibre Reinforced Polymer (CFRP) reinforcement. Four different beam configurations have been investigated, each at 20°C, 50°C and 70°C. Test results have shown that, compared to room temperature, the type of failure and the failure load of the beams tested at 50°C were not significantly affected. At 70°C, the type of failure changed for one of the beams from failure in the concrete adjacent to the concrete-adhesive interface to failure exactly in the concrete-adhesive interface. The failure loads of the beams tested at 70°C were not significantly affected compared to room temperature, except for the beam with a relatively short laminate length. For this beam, the load capacity is expected to be mainly related to the capacity of the end anchorage zone, which was negatively affected by the effects of the elevated temperature