The mechanism of load transfer in a pretensioned beam entirely depends on the bond characteristics between the tendons and the concrete. This paper investigates the bond performance of two types of carbon fibre based (CFRP) and two types of polyaramid fibre based (AFRP) tendons. Sections of Fibre Reinforced Plastic (FRP) tendons were observed using a Scanning Electron Microscope (SEM) in order to characterize the initial surface configurations. With the characterization of the surface configurations of these FRP tendons, the bond between the tendon and the concrete can be better understood. The compressive strength of the concrete used for the pretensioned beams ranged from 40 MPa to 100 MPa and the cementitious materials included silica fume which had a mean particle size of about 0.1 μm. The effect of particle size of silica fume, cement, fine aggregate and coarse aggregate and the nature and size of hydration products (surrounding the FRP tendons) on the bond strength of FRP have also been studied. Bond-slip relationship between the FRP tendons and concrete was established by standard pull-out tests of concrete specimens. The bond performance of FRP is compared with a plain steel wire and a steel strand. In this paper, the experiments carried out, the results obtained and the main conclusions are presented.
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