Mechanical behaviour of concrete-resin-FRP interfaces under temperature ranging from -40°C to 80°C

The application of FRP to the strengthening of existing reinforced concrete structures is involved with the inevitable exposure of the layered structure to various temperature changes during its lifetime. While the FRP/resin (adhesive)/concrete interface ageing has already been studied, only few results can be found in the field of the combined effect of temperature and mechanical load. This paper takes another step in the investigation of the behavior of concrete to FRP link under the combined effect of temperature change and load. The investigation refers to a double lap shear testing conducted in a temperature controlled chamber under temperatures in the range of -40°C to 80°C. The FRP system is made of carbon fibers and epoxy adhesive/resin applied by the wet lay-up method. The emphasis in this paper is on two new directions that help exploring and explaining the response of the layered structure to the combined mechanical and environmental loading systems. The first one is the characterization of the mechanical properties of the adhesive or resin used for joining the layered structure together under the examined range of reduced or elevated temperatures. The second one looks into the results of an analytical approach that uses a high order fracture mechanics model of the debonding structure. The two directional aim to throw some light on the interaction between the thermal and the mechanical effect and on the impact of temperature change on the resilience of the layered structure.