Structural Performance of FRCM/CRM-Strengthened Calcarenite Masonry: Experimental and Numerical Investigation on Shear Behaviour of Panels and Asymmetrically Loaded Barrel Vaults

The conservation and strengthening of existing masonry buildings represent one of the main challenges in structural engineering, particularly in the context of the preservation of the built heritage, due to the vulnerability of these structures to seismic actions and the need to ensure an adequate level of safety while preserving their historical and architectural value. This need drives research into the mechanical behaviour of common structural elements, such as walls, arches and vaults, with a view to understanding their load-bearing mechanisms under severe conditions and identifying effective and compatible reinforcement strategies.In recent years, inorganic matrix composites, including Fabric Reinforced Cementitious Matrix (FRCM) and Composite Reinforced Mortar (CRM) systems, have emerged as innovative solutions for reinforcing masonry structures. Despite extensive research in this area, several aspects still require further investigation. While technical documents are available to support the design of FRCM systems, recent experimental results have highlighted the need to investigate the numerous variables involved in their application in greater depth, with a view to updating and improving current calculation methods. Existing formulations for the shear reinforcement of masonry panels focus primarily on the mechanical properties of the fabric, while neglecting the contributions of the matrix, connectors, and complementary geometric parameters. Further studies are also required to assess the compatibility of the reinforcement system with the masonry substrate in terms of both the materials used and the mechanics involved.The formulations developed for FRCM systems are not directly applicable to CRM systems due to differences in geometry, mechanics and behaviour. Furthermore, the available experimental evidence, particularly on full-scale structural elements, remains limited. Another growing area of interest is the potential use of CRMs as integrated systems for improving the structural performance and energy efficiency of buildings.The aim of this research is to expand the experimental database available in the literature and contribute to a better understanding of the effectiveness of these technologies. To this end, an extensive experimental programme is carried out on structural elements made of calcarenite masonry, a material widely used in historic city centres in Mediterranean regions. The study focuses on two critical vulnerabilities commonly observed in historic masonry buildings subjected to seismic actions: the in-plane shear strength of walls and the structural behaviour of barrel vaults. The effectiveness of FRCM and CRM systems for shear reinforcement was evaluated using diagonal compression tests on masonry panels. In parallel, the behaviour of barrel vaults reinforced with CRM systems featuring both traditional and geopolymer matrices was analysed through mechanical tests under asymmetric loading conditions. This helped to expand the limited knowledge available in the literature. Thermal tests were also conducted on the same vaults to evaluate the potential application of CRM as a dual structural and energy retrofitting solution.The entire experimental campaign was supported by the 2 Dimensional Digital Image Correlation (2D-DIC) technique, which was used to monitor strain field evolution, cracking phenomena, and delamination processes. The experimental work was complemented by simplified and detailed numerical modelling, which was employed as a predictive tool and to aid interpretation of the results.The results of the diagonal compression tests were incorporated into a database of experimental data from the literature. This was done with a view to analysing the main influencing parameters, as well as contributing to the validation and updating of existing calculation formulations. On the other hand, the results relating to vaults and the use of CRM systems as an integrated solution provide an original contribution to the development of intervention strategies aimed at jointly optimising the structural and energy performance of existing masonry buildings.