Bonding behavior between reinforced concrete after fire and carbon fiber reinforced polymer

Abstract

Nowadays, the fire accidents of building frequently occur in many countries including in Thailand and cause severe damages to structures. Those critical incidents can diminish the concrete strength, reduce bond strength between concrete and steel reinforcement and spalling occurs on concrete surface. Consequently, the structural repair by strengthening with Fiber Reinforced Polymer (FRP) is one of the popular solutions owing to high strength to weight ratio, high corrosion resistance and conveniently in situ at construction site. This research focused on the effects of interfacial bond stress in order to investigate the bonding behavior of concrete exposed to fire according to standard temperature-time curve of ASTM E119. To accomplish this, the strain distribution was obtained from the modified pull out test and three parameters were varied; concrete covering, bond length and exposed time to fire. Concrete specimens varied with concrete covering 1, 2 and 3 cm were burnt with different time exposures (0, 45 and 90 minutes) and attached with Carbon Fiber Reinforced Polymer (CFRP) through epoxy. The attached CFRP also had various bond lengths; 15, 20 and 30 cm. Finally, the important parameters for bonding behavior were shown in term of interfacial fracture energy from experimental data.