Bond between near-surface mounted fiber-reinforced polymer rods and concrete in structural strengthening

The use of near-surface mounted (NSM) fiber-reinforced polymer (FRP) rods is a promising technology for increasing flexural and shear strength of reinforced concrete (RC) members. As this technology emerges, the structural behavior of RC elements strengthened with NSM FRP rods needs to be fully characterized, and bond is the first issue to be addressed. Bond is of primary importance since it is the means for the transfer of stress between the concrete and the FRP reinforcement to develop composite action. The objective of this research program was to investigate bond between NSM FRP rods and concrete. Some of the factors expected to affect bond performance were addressed, namely: bonded length, diameter and surface configuration of the rod, type of FRP material, and size of the groove in which the rod is embedded. Results are presented and discussed in this paper.