Performance of non-structural masonry retrofitted with welded wire mesh and steel fibers under axial compression load

This paper evaluates the behavior of non-structural masonry built with horizontal hollow clay bricks. The aims of the study are to reduce the structural vulnerability of houses built with this type of bricks in seismic zones of Latin America, especially Colombia and Ecuador. The tested specimens were 50 centimeters wide, approximately 10 centimeters thick and 1 meter high. The retrofitting methods consisted of two types of reinforcement: the first one with a 3:1 sand:cement ratio. (S:C) mortar overlay with 2.5 centimeters thick for overlay the welded wire mesh (WWM) (φ4mm/15cm) adhered to the masonry with plastic anchors on each face of the wall. The second one with the use of mortar overlay reinforced with steel fibers (SF20) using a dosage of 20 kg/m³, with an average thickness of 2.5 centimeters and a 3:1 S:C ratio. The experimental program included the testing of 13 axial compression specimens, 4 prisms for compression with WWM reinforcement, 4 prisms for compression with SF20 reinforcement, 4 with plain mortar overlay and 1 control masonry without any type of reinforcement, only with hollow bricks. Each type of reinforcement was assessed using a monotonic quasi-static axial compression test and 3 quasi-static cyclic tests. The results showed that SF20 reinforcement increases the compressive strength, controls crack growth, but the failure mode is fragile. On the other hand, the WWM reinforcement shows a lower compressive strength, but a less fragile failure mode since the more cracks are visualized and their size increases as the load increases in the test. This is also evident in the load-deformation curves. The WWM reinforcement does contribute to life safety, by holding the collapsed clay block fragments between the mortar diaphragms. In addition, it was observed in the experimental tests that the resistance can be increased by ensuring a continuous anchorage that holds the WWM on both faces of the horizontally drilled bricks. Finally, as a conclusion, the increase of resistance by SF20 reinforcement generates stiffer prisms for compression, but it would not guarantee life protection in case of cracking or collapse of masonry walls; on the other hand, WWM does allow greater deformations, despite not having a similar resistance as the walls reinforced by SF20.