This paper presents experimental study carried out on un-reinforced concrete beams strengthened with well-known reinforced technique, such as externally bonded Fiber Reinforced Polymer sheets (FRP) to concrete surface using epoxy adhesive. This technique is compared to both of externally bonded FRP sheets using cement-based material and externally strengthening with Fiber-added Reinforced Concrete (FRC). A total of 12 un-reinforced concrete beams strengthened with Glass Fiber-added Reinforced Concrete (GFRC), glass FRP bonded to concrete using cement-based bonding agent, and GFRP bonded with epoxy adhesive have been tested. Efficiency of each type of strengthening in flexure was investigated through three-point loading test. Results are analyzed with regard to the load-displacement curve, bending stiffness and failure load. The Results showed that strengthening system using the epoxy adhesive as bond agent gives high failure load. However, the use of cement-based bonding materials is a promising technique in FRP applications for structures located in hot regions or in danger of fire.