Effect of temperature on RC elements strengthened with CFRP

The strengthening of RC elements with CFRP is a technique that has been acquiring more and more potential. The bond between the CFRP reinforcement and the concrete support is usually made with epoxy adhesives. However, it is here that the integrity of the system can be affected, namely by exposure to high temperatures. In order to study the effect of an increase of air temperature on the behaviour of the epoxy adhesive, CFRP strengthened RC and reference RC specimens were tested. After cyclical thermal exposures, with temperatures rising between 20 and 80 degrees C, specimens were subjected either to compressive shear tests or bending tests. The results demonstrated that epoxy adhesive exhibits poor behaviour when subjected to increased temperatures, causing important bond deterioration. The improvement achieved with the CFRP reinforcement tends to disappear with an increase of the environment temperature. So, the thermal resistance of this strengthened system cannot be considered very high. However, the inclusion of insulating materials can be a good solution to protect the strengthened RC elements. Among tested materials, the foamed polyurethane showed the best behaviour.