Experimental Investigation on FRCM System for Shear Strengthening of Masonry Panels

The use of Fabric Reinforced Cementitious Matrix (FRCM), due to the inorganic matrix, has become widely popular as a retrofitting technique for historic buildings. This system increases the load-bearing capacity of masonry elements and compared to other composite materials, provides better compatibility with this type of substrate. Despite this, the literature and guidelines are still limited, although research is moving towards the characterization of this type of material when used on masonry substrates. The variables involved in assessing the strengthening effect are numerous and depend on different combinations of materials (i.e., mortar, fibres, and substrates). This study aims to evaluate the effectiveness of two systems, namely FRCM with glass and carbon fibre-based fabrics, in increasing the capacity of masonry panels when subjected to in-plane stresses by performing diagonal compression tests. The FRCM strengthened panels are made of calcarenite units, a common material in historic Sicilian constructions. The experimental campaign included tests on unreinforced samples, panels strengthened with two layers of FRCM, one on each side, and a panel with two layers connected with glass fibre connectors.. The mortar used as matrix is a fibre-reinforced lime-based mortar suitable for block and stone masonry. Glass fibre connectors were made in the laboratory from a high-strength unidirectional glass fibre rope. The objective was to evaluate the strength and ductility gains and compare results using the two types of fibres. The contributions of the connectors were also evaluated, focusing on the failure modes.