Behaviour of concrete beams reinforced with hybrid FRP composite rebars

Recent extensive research has led to a better understanding of the application of various corrosion protection methods in reinforced concrete (RC) structures. One method is to use fiber reinforced polymer (FRP) composite rebars for conventional reinforcement in concrete. However, obstacles such as low elastic moduli, low pre-rupture elongation, brittle fracture, poor alkaline resistance as well as high cost currently restrict the use of composite rebars as a common construction material. In order to overcome such deficiencies, a new core-shell model of a hybrid composite rebar was developed for RC structures. In this new model, steel fibers and glass fibers randomly dispersed through the cross section of the core, while Kevlar and carbon fibers are placed within the shell to increase the elastic modulus, as well as to serve as a shield for protecting the glass fibers and the steel fibers from alkaline attack. Samples of the new hybrid composite rebars were fabricated by the hand winding method, and a series of concrete beams, reinforced with the hybrid FRP rebars, were tested to determine the bending moment capacity and mechanical properties of the beams. The test results were compared with those of traditional RC beams. The hybrid FRP rebars were also studied in accelerated alkaline ageing tests, using concrete pore solutions at different temperatures, and their service life and alkaline resistance were determined