Anchorage and tension-stiffening effect between near-surface-mounted CFRP rods and concrete

The aim of the experimental program developed in this work was to investigate the effects of concrete strength, filling material, groove dimensions, groove surface preparation for such CFRP rods used in the Near-Surface Mounted reinforcement (NSM) technique. Two interfaces are involved in the NSM technique: one between the reinforcing composite rod and the filling material and the other between this material and the old concrete. The coupling between the two interfaces was studied through two mechanical tests: the usual pull-out test, which assessed the anchoring capacity of the CFRP rods, and the tension member test, which simulated the behavior of the CFRP rod bond in the tensile zone of an RC-structural element. The specimen was designed to study the specific problems of NSM: reduction of contact surface area between filling material and concrete and eccentricity of FRP rods. The rods were 12-mm-diameter carbon-epoxy pultruded FRP. The experimental results indicate that NSM technique gives satisfactory results for both anchoring and reinforced concrete flexural member strengthening. (C) 2010 Elsevier Ltd. All rights reserved.