Preliminary results of experimental study on the diagonal compression behaviour of masonry panels retrofitted with FRCM

The use of composite fibre grids embedded in an organic matrix, namely Fabric Reinforced Cementitious Matrix (FRCM) and fibre mesh in a mortar plaster, e.g., Composite Reinforced Mortar (CRM), were increasingly applied in structural retrofitting applications and already known by the scientific community. Both systems have promising results in improving the structural performances of masonry members, such as walls, arches, and vaults. This is due to their load-carrying capacity and their great compatibility with masonry substrates, compared to other types of organic matrix composite materials. However, the literature on these strengthening systems is still quite limited, and limited research is available regarding their mechanical properties and the behaviour of strengthened masonry members. In this work, preliminary results and considerations of the experimental campaign are presented, with the goal of examining the effectiveness of various strengthening options for increasing the in-plane shear behaviour of masonry. Single-leaf masonry panels reinforced with FRCM and CRM systems using various fibre typologies and arrangements are tested under diagonal compression tests. Masonry panels are made of calcarenite stone units, a material typically used in historic Sicilian (in the South of Italy) constructions. The mortar used as a matrix is a fibre-reinforced lime-based mortar which is medium-grained and suitable for structural work on stone and brick masonry, even where there are historical and architectural constraints. Concerning the type of fibre, a glass grid and a carbon grid are used for the FRCM system, while a Glass-FRP grid is used for the CRM system. The planned experimental campaign involves the construction of masonry panels with different retrofitting systems, including control specimens, panel retrofitted with FRCM, and panels reinforced with the CRM system. The main objective is to evaluate the gains in shear strength and ductility of retrofitted masonry panels and to compare the results for different system types and configurations, also in terms of failure.