The effect of long-term loading on the CFRP-concrete bonding strength

Results of an experimental campaign concerning the long-term behavior of FRP plates bonded to concrete are presented. Four CFRP plates with three different bonded lengths (from 100 mm to 400 mm) have been subject to long-term constant traction force. The tests have been carried out in a climatic room with a constant temperature T=20°C and humidity RH=60%, for about five years. The strain profile evolution with time along the bonded length has been recorded by using a number of strain gauges along the plates. An appreciable stress redistribution with time along the plate has been observed. At the end of the long-term test, all specimens have been subjected to failure load in order to verify if the interface behaviour was affected by the long-term loading application. No remarkable degradation has been found.