Textile Reinforced Mortar (TRM) systems are a class of composite materials widely adopted for the structural strengthening of masonry constructions. They are usually made of inorganic matrix, which can be a lime-based or cement-based mortar, and are reinforced with layers of strengthening grids, often made of steel or glass fibres. In recent years, growing concern about sustainability has increased the interest towards materials with a lower environmental impact, by favouring the adoption of natural fibres in TRM systems. These systems are also known as Natural Textile Reinforced Mortar (NTRM). In this research, basalt-TRM composites are analysed for the structural strengthening of masonry cross vaults subjected to quasi-static shear settlement of two abutments. The mechanical characterization of the strengthening system is conducted by direct tensile tests on bare textiles and one-layer composite coupons. The durability of the strengthening system is assessed by applying an ageing protocol to both basalt textiles and composite coupons. In detail, the bare textiles were conditioned for 1000 h at 23 ℃ in a 0.16% Ca(OH)2 alkaline solution, simulating the exposure to a lime-based-mortar aggressive environment. Meanwhile, the composite coupons were conditioned for 1000 h in water at a constant temperature of 23°. The tensile strength of conditioned samples is compared to those of the non-aged reference specimens. Then, the Finite Element (FE) simulation of a masonry cross vault is performed to assess the efficiency of the basalt-TRM strengthening system applied to the extrados, incorporating the mechanical properties of the composite material.