Bond Behavior between Near-Surface-Mounted CFRP Strips and Concrete at High Temperatures

Fire behaviour of FRP-strengthened reinforced concrete structural elements: A state-of-the-art review

“…The first issue should be pursued in future studies as its influence on bond strength has yet to be confirmed and quantified. The second issue has been confirmed in various studies [31,35], however in which bond strength decreased within this temperature range. It is noteworthy that a common feature to all studies in which the bond strength increased at elevated temperatures below T g is that the specimens in these studies were all conditioned at elevated temperature for long durations (12 h or more) prior to structural testing.…”

“…Unsurprisingly, the available literature also confirms the superior bond performance at elevated temperature with either anchorage systems or adhesives with higher T g . Finally, these studies [31,35] have also confirmed the superior bond performance at elevated temperature of NSM as compared with EBR systems.…”

“…6 show that generally, at temperatures moderately above T g , the bond strength may remain considerable. Firmo et al [31,35] have attributed such bond strength reserves to frictional forces at the bonded interface, particularly for NSM systems. Unsurprisingly, the available literature also confirms the superior bond performance at elevated temperature with either anchorage systems or adhesives with higher T g .…”

“…Firmo et al [35] conducted double lap tests on concrete blocks strengthened with NSM CFRP strips at temperatures between 20 C and 150 C. Two bonding materials were used, an epoxy adhesive (T g of 47 C, determined by DMA) and a mixed grout with both cement and epoxy binders (T g of 44 C, determined by DMA). Regardless of the adhesive used, as in the companion study on EBR CFRP-concrete interfaces [31], elevated temperature caused a consistent reduction of bond strength, more linear strain distributions along the bonded length, an increase of effective bond length, bondeslip relationships with lower stiffness and maximum shear stress, and a change in the failure mode (from cohesive within the concrete block to adhesive at the CFRP-adhesive interface).…”

Fiber Reinforced Polymer Strengthening of Structures by Near-Surface Mounting Method

“…In this section, several existing studies in the literature related to NSM-FRP reinforced members subjected to temperature are discussed. Main test variables, specimen conditions, insulation types and failure modes, of these investigations are presented in Table 6 [43,44,45,46,47,48,49,50,51,52]. Yu and Kodur [43] revealed that the NSM-CFRP strips and bars themselves provided better resistance to high temperatures in comparison to external FRP laminates and internal FRP reinforcement.…”