Un-reinforced masonry walls (URM) are one of the oldest and most widely used types of construction in the world but they are prone to failure when subjected to over-stresses caused by out-of-plane and in-plane loads. URM can fail for many reasons including structural weakness or overloading, dynamic vibrations, settlements, wind pressure, earthquakes. Recent failures of masonry walls around the word have driven to the development of new techniques for the repair and strengthening of URM walls.

The use of near-surface-mounted (NSM) FRP bars is an attractive method for increasing the flexural and the shear strength of deficient RC members and masonry walls and, in certain cases, can be more convenient than using FRP laminates. This technique consists of placing a bar in a groove cut into the surface of the member being strengthened. The FRP bar may be embedded in an epoxy or latex modified cementitious paste, which transfers stresses from the substrate to the bar. Application of NSM FRP bars does not require any surface preparation work and requires minimal installation time compared to FRP laminates. Another advantage is the feasibility of anchoring these bars into members adjacent to the one to be strengthened. For instance, in the case of the strengthening of a masonry infill with FRP bars, they can be easily anchored to columns and beams.

At the moment, due to the high cost of the embedding materials, the NSM FRP bars technique applied to the masonry has not found many applications. Thus, find more economical materials for encapsulating the bars is a need: these materials may be mortars with improved bond properties, which can transfer tensile stresses to the reinforcement.

Therefore, the purpose of this experimental program is to analyze the characteristics and the effectiveness of the NSM GFRP bars by using a cementitious-based paste as matrix. Since this is the first time that cementitious paste has been used with FRP materials, the entire experimental program is based on the comparison between using epoxy-paste and cementitious-paste.

In more details, the addressed issues were to evaluate the bond behavior by using GFRP NSM rods embedded in two different matrixes, to illustrate the ability of this system to increase flexural and shear capacity of the masonry walls and to provide design guidelines and recommendations.

Obviously, these design approaches have to be validated and modified by future experimental programs, since these are the means through which an experimental technology can become accepted field practice.