Polypropylene as a Retrofitting Material for Shear Walls

In the recent years, on account of their excellent mechanical properties, composite materials (made of epoxy-bonded carbon, glass or aramid fibers) have been used to reinforce masonry walls against in-plane actions. These materials have proven to be an effective solution for the strengthening of unreinforced masonry (URM) walls. Lately, research shift to the study of different types of fibers to avoid the use of epoxy adhesives, whose long-term behavior and compatibility with masonry are poor. This paper describes an experimental program on the behavior of URM shear walls strengthened with two types of commercially available polypropylene products: short fibers (fibre length = 12 mm) and polypropylene nets. This investigation intended to evaluate the influence of polypropylene reinforcement, embedded into an inorganic matrix, for improvement of the lateral load-carrying capacity, failure mechanism, ductility, and energy-dissipation capacity of URM wall panels: 9 walls were subjected to in-plane loads using a racking test setup. The study showed that using two layers of polypropylene fibers embedded into a cementitious matrix has highly increased the in-plane load capacity of the brickwork masonry. On the other hand, test results indicated that polypropylene nets, used as a repair method for cracked shear walls, cannot improve the structural performance of the walls.