Alkali and temperature long-term effect on the bond strength of fiber reinforced polymer-to-concrete interface

Abstract

The effects of such environmental conditions as alkali media at temperatures of 23℃, 40℃, and 60℃ were investigated on the fiber reinforced polymer-to-concrete bond strength. For this purpose, 42 specimens were strengthened via the externally bonded reinforcement and the externally bonded reinforcement on grooves techniques. The specimens were later subjected to the single-shear test after the specified durations of exposure to an alkaline medium. The particle image velocimetry technique was used to investigate such bond characteristics of the strengthened specimens as load-slip behavior, strain profiles, and strain fields along the fiber reinforced polymer-to-concrete bond. Experimental results showed that the specimens strengthened via the externally bonded reinforcement on grooves method exhibited ultimate bond loads by up to 50% higher than those strengthened via the externally bonded reinforcement method.

CFRP-to-concrete bond behavior under aggressive exposure of sewer chamber

“…Finally, FRP sheets are installed using proper amounts of the epoxy on the concrete surface. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] In both strengthening methods, FRP sheets were cut into pieces 735  48 mm (length  width) bonded on 200 mm of the concrete surface, leaving 35 mm unbonded to avoid stress concentration. 13,25 Besides, a length of 500 mm of the FRP sheet was left as the free end length.…”

CFRP-strengthened RC beams under fire condition: numerical model

“…The failure of bond generally occurs at temperatures near or above the Glass Transition Temperature (T g ) 1 of the adhesive. Glass Transition Temperature is the point at which a material alters state -going from a glass-like rigid solid to a more flexible compound.…”

“…However, in some cases, the bond failure happens for temperatures below T g . The T g of the adhesive varies usually from 50 and 120 ºC [1]- [5], depending on the polymeric matrix of constituents and the type of resin, among others. The better understanding of the temperature effects on this type of structures makes it possible for reliable and safe design in case of fire.…”