Bond Characteristics of Glass Fibre Reinforced Polymer Bars Embedded in High Strength and Ultra-High Strength Concrete

摘要

The use of high strength concrete (HSC) and ultra-high strength (UHSC) with glass fibre reinforced polymer (GFRP) bars in construction is an emerging technology. The performance of reinforced concrete depends on the transfer of forces between the concrete and the reinforcement, which depends on the quality of the bond between the two materials. Studies have attempted to understand the bond behaviour of FRP rebars in concrete, however, the complexity of the parameters that influence the bond behaviour and the diverse types of commercially available FRP bars have made it difficult to establish a comprehensive understanding. In this study, the bond characteristics of sand coated GFRP bars embedded in HSC and UHSC concrete were explored. 32 beam tests were performed to determine the effects of the concrete strength, bar diameter, embedment length, and the concrete cover on the bond behaviour of GFRP bars. 15.9 mm and 19.1 mm diameter GFRP bars were used with embedment lengths of three, five and seven times the bar diameter. This research showed that the compressive strength had a minimal affect the bond behaviour of concrete in HSC and UHSC and that it was related to the hydrostatic pressure due to the low w/c_m. It also showed that the bleed water trapped beneath the bar caused the bond strength of the 19.1 mm GFRP bar to be 6% lower than the 15.9 mm GFRP bar and that the addition of fibres created a localized disturbance in the bond interface of the GFRP bar. The research also showed that the bond strength decreased with the increase in embedment length.