Durabiliy Of The Bond Performences Of High Strength Concrete Strengthened With CFRP Under Loading And Environmental Conditions

In recent years, large-span and high-rise structures are widely used with the development of the construction industry, consequently, high strength concrete are increasingly applied. Nevertheless, the failure of high strength concrete is brittle due to the poor ductility. Therefore, the rehabilitation and strengthening of high strength concrete structures come into focus. Becausce of good mechanical properties, high corrosion resistance and increasingly affordable price, CFRP has been widely used in structural reinforcement and rehabilitation. Good bond peformence of interface between CFRP and concrete is the key to make this strengthening method effective. CFRP reinforced concrete structure is usually exposed to harsh environment, the durability of these structures has restricted the promotion of this technology. Based on the above background, the paper has discussed durability of interfacial bond performance between CFRP and high strength concrete under couple action of sustained load and environments. The main contents are as follows:(1) The interfacial bond performance between CFRP and high strength concrete under couple action of sustained load and freeze-thaw cycle was studied. Experimental results showed that, elastic modulus of CFRP under couple action of sustained load and freeze-thaw cycle was not adversely affected; with the increase in the number of freeze-thaw cycle, initial debonding load, failure load, ultimate global slip, elastic modulus and fracture energy tended to decrease; sustained load caused additional damage to the interface under frost environment, the higher level of sustained load was, the more seriously interface was damaged.(2) The interfacial bond performance between CFRP and high strength concrete under couple action of sustained load and dry-wet cycle was studied. Experimental results showed that, elastic modulus of CFRP under couple action of sustained load and dry-wet cycle was not adversely affected; with the increase in the number of dry-wet cycle, initial debonding load, failure load, ultimate global slip, elastic modulus and fracture energy tended to decrease; sustained load caused additional damage to the interface under dry-wet environment and failure mode was changed by the shift to adhesive failure between resin and concrete from concrete shearing failure.