International Conference on Advances in Structural and Geotechnical Engineering ICASGE’15 6-9 April 2015, Hurghada, Egypt 1 EFFICIENCY OF CEMENT BASED BONDING AGENT FOR FRP SHEETS VERSUS EPOXY HESHAM DIAB 1 1 Civil Department, Assiut University, Assiut 71516, Egypt. E-mail: heshamdiab2@yahoo.com 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. Keywords: Concrete, FRP sheets, Epoxy, Cement-based bonding agent 1 Introduction Strengthening of Reinforced Concrete (RC) structures based on the application of fiber reinforced polymer (FRP) has become an accepted solution in the last decades, presenting many advantages, such as high strength-to-weight ratio, corrosion resistance, and relative ease of application (Ferrari et al. 2013). It has been shown through experimental and theoretical studies that externally bonded FRP composites using epoxy adhesive improves the desired performance of a structural member such as its load carrying capacity and stiffness, ductility, and performance under static and fatigue loading (Diab and Farghal 2014, Diab and Wu 2008). Despite evident advantages of FRP technique over other strengthening methods, some aspects still need to be investigated (Di Ludovico et al. 2008) Indeed, organic epoxy resins imply some drawbacks such as; do not adhere well to wet surfaces, are sensitive to low temperature, in practical during curing, and have low performance under direct fire. The greatest obstacle to applications of FRP to concrete element using epoxy resin is the degradation of mechanical and bond properties when it exposed to high temperature. The fire behaviour of FRP composites depends mainly on the behaviour of the epoxy adhesive. At elevated temperatures, normally beyond the glass transition temperatures of epoxy adhesive, the mechanical properties of the polymer matrix deteriorate rapidly (Wu et al. 2005). The exposure to elevated temperatures will lead to rapid and severe deterioration of FRP- strengthened structures, even though the FRP composites themselves have very good thermal performance. Gamage et al. (2006 and 2009) has noticed a rapid strength loss in epoxy bond