A strengthening technique for existing masonry based on FRP mesh reinforced mortar coating. Influence of the strength of the mortar

Many experimental tests were carried out on different types of masonry: solid brick masonry (different thickness), rubble stone masonry, cobblestone masonry, two-leaf brick masonry with very poor infill. The role of type of masonry mortar, type of reinforcement, number of connectors was also investigated. The scope of the study was to check the influence of the resistance and the thickness of the mortar coating through a specific experimental campaign of diagonal compression tests. 16 different types of mortar, with tensile strengths ranging from 0.76 to 2.97 MPa, were considered. The resistance of the reinforced masonry specimens is appreciably influenced by the mechanical characteristics of the mortar coating, but the dependence to each parameter is not known yet. An analytical formulation for the calculation of the resistance of reinforced masonry was proposed: the summation of the unreinforced masonry resistance to that of the coating multiplied by a coefficient β, which depends on strength and stiffness of the coupled materials. A characteristic curve for β in function of the tensile strength of the β g coating was drawn: an exponential function with decreasing trend and with a horizontal asymptote at 0.8. For small thickness coating slightly better performances were found for equivalent reinforcement.