EVALUATION OF THE LOCAL MANUFACTURING AND BOND BEHAVIOUR OF GFRP RODS HYBRIDIZED WITH STEEL WIRES FOR CONCRETE REINFORCEMENT

Steel erosion and environmental harm caused by manufacturing of steel bars, motivate engineers and material scientists to define new alternatives for the oldest material in construction. Even though, Fibre-Reinforced Polymers stands as a promising alternative, the low modulus of elasticity barriers their wide-use. Recently, hybridization of FRP with steel leads to a new type of reinforcement which can be used as a good alternative to steel rods and overcome the flaw of low modulus of elasticity of conventional FRP. Depending on the ratio of hybridization an approximately 200% increase in the modulus of elasticity with sufficient tensile strength is experimentally proved. Still, the ability of the new rods and their integration with surrounding concrete were not extensively studied in previous studies. Bonding between new rods and the surrounding concrete is a key parameter to assess the integrity of reinforced concrete components. Therefore, this paper investigates the bonding behaviour of the new hybrid rods with concrete. The manufacturing techniques for the used hybrid rods are first presented then, the bonding between the rods and concrete is investigated using pull out test. Two types of reinforcement, glass FRP rods and Hybrid wire FRP rods of 8 mm, 10 mm and 12 mm diameter were used in this study. Several relevant factors have been considered in this study including concrete compressive strength and the rod diameter among other parameters. It has been concluded that the bond strength increased by increasing in concrete compressive strength while the bond strength between the surrounding concrete and the hybrid wires FRP rods decreased with the increasing of the rod diameter and the increasing of embedded length from rods. Eventually, it has been shown that ribbing of rods surface has a significant enhancement on the bond strength.