Near Surface Mounted GFRP Strips: An Overview

The use of glass fiber-reinforced polymer (GFRP) materials for strengthening bridges and buildings has been used extensively in the last decade. Glass fiber reinforced polymer has been used in different configurations and techniques to use the material effectively and to ensure long service life of the selected system. One of these innovative strengthening techniques is the near-surface mounted (NSM) that consists of placing Glass fiber reinforced polymer reinforcing bars or strips into grooves pre-cut into the concrete cover in the tension region of the concrete member. This method is relatively simple and considerably enhances the bond of the mounted Glass fiber reinforced polymer reinforcements, thereby using the material more effectively. NSM Glass fiber reinforced polymer reinforcing bars and strips is practical, significantly improves the stiffness, and increases the flexural capacity of reinforced concrete beams. Strengthening of reinforced concrete beams using NSM Glass fiber reinforced polymer strips provided higher strength capacity than externally bonded FRP strips using the same material with the same axial stiffness. Issues raised by the use of NSM GFRP reinforcement include the optimization of construction details, models for the bond behaviour between NSM GFRP and concrete, reliable design methods for flexural and shear strengthening, and the maximization of the advantages of this technique. This paper provides a critical review of existing research in this area, identifies gaps of knowledge, and outlines directions for further research.