Influence of short fibres in FRCM-matrix on the in–plane shear ductility of masonry walls: A preliminary study

A substantial portion of existing masonry structures is both ancient and highly vulnerable to seismic actions, particularly when assessed against modern technical regulations that demand performance levels far beyond those achieved at the time of their construction. In this context, the inherent energy dissipation capacity of masonry walls during seismic events such is markedly insufficient. The historical nature of these buildings further complicates the selection of suitable retrofitting solutions, as interventions must balance structural effectiveness with material compatibility and preservation requirements. Among the available techniques, fabric–reinforced cementitious matrix (FRCM) systems have recently gained prominence due to their favourable compatibility with diverse substrates and their proven ability to enhance shear strength. This research investigates the potential of FRCM retrofitting for masonry walls, with particular emphasis on improving shear behaviour through the incorporation of short fibres within the mortar/matrix. To this end, a preliminary experimental campaign was conducted on small-scale masonry panels subjected to diagonal compression tests, with shear stress–strain behaviour monitored until failure. The results show that FRCM strengthening increased shear strength by up to 63% and more than doubled ductility, while the incorporation of 1% PVA fibres further enhanced cracking resistance and energy dissipation. The findings demonstrate the effectiveness of combining fabric reinforcement with short fibres, leading to enhanced shear strength, improved ductility, and a transition from brittle failure to distributed cracking. • Experimental test on masonry panels strengthened with FRCM- and ECC-systems. • Validation and critical understanding of available design-oriented model.