Fabric-reinforced cementitious matrix (FRCM) composites are a new class of materials used to repair and strengthen existing structures. Mechanical performance varies widely based on the type and volume of fibers, fabric architecture, mortar properties, and bond characteristics. Moreover, test setup and boundary conditions are of the utmost importance for their mechanical characterization because of the complex interaction between fabric and brittle matrix. Therefore, the challenge is to define characterization and acceptance criteria that are (1) suitable for a wide spectrum of existing FRCM systems, and (2) produce representative values for the design of strengthened members. In this paper, three FRCM systems comprising carbon, glass, and steel fabrics were tested in accordance with two different acceptance methods. One method, which has been developed and adopted in the United States, is based on tensile tests on FRCM coupons with a clevis-grip mechanism that allows slippage at the fabric–matrix interface and provides mechanical properties that are directly used for design. The other method, developed within RILEM TC 250-CSM, combines the results of clamping-grip tensile tests on bare textile specimens with those of FRCM-to-substrate shear bond tests to obtain mechanical properties accounting for a broad range of possible failure modes. The results provided by the two methods are discussed and compared in relation to FRCM field applications.

In a period characterized by the urgent need of enhancing the safety level of the building stock, including architectural heritage, externally bonded textile-reinforced mortar (TRM) systems are emerging as a particularly advantageous strengthening solution. Their use on unreinforced masonry arched members appears one of the most promising fields of application, but an improved understanding still needs to be gained on the behavior of TRM retrofitted interstorey vaults. This article describes an experimental investigation on full-scale masonry vaults, provided with buttresses and backfill, reinforced with basalt textile-reinforced mortar (BTRM) overlays either at the intrados or at the extrados. Cyclic load was applied at 1/3 span over the backfill. Digital Image Correlation was used to detect full-field displacements and map crack development. Both strengthening solutions proved effective in delaying crack occurrence and improving arch-fill interaction, enhancing both load-carrying and deflection capacity. A limit analysis-based method provided reliable ultimate strength estimates for engineering design and assessment purposes.