a b s t r a c tFabric Reinforced Cementitious Matrix (FRCM) composites are advanced cement-based materials often used for strengthening masonry or concrete structures. The system is usually composed of a dry grid of fibers embedded in a cementitious matrix enriched with short fibers.An important parameter for designing the structural reinforcement is the tensile load-bearing capacity of FRCM composites. For their heterogeneity, FRCM composites show an interesting mechanical behavior in tension, that depends on the properties of the components and of the bonding strength. These values could be estimated with mechanical models but must be validated experimentally by means of proper testing campaigns.In this work several FRCM materials made with different fiber grids were investigated. Four different types of fibers were considered: polyparaphenylene benzobisoxazole (PBO), carbon (C), glass (G) and PBO and glass (PBO-G) fibers and three different types of cementitious mortars.The behavior of FRCM under tension and the influence of the bond properties between the dry textile and the inorganic matrix are studied developing an extensive experimental program that included the characterization both of the materials components and of the composites. A series of push-pull double lap tests and pull-off tests were performed to determine the bonding properties of FRCM composites applied to masonry structures.The paper presents results and considerations that can provide background data for future recommendations for the use of FRCM systems in the rehabilitation of elements.

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Fabric-reinforced cementitious matrix (FRCM) composites made of dry-fiber fabric embedded in an inorganic matrix are advanced cement-based materials designed for retrofitting masonry or concrete structures. Characterization of the tensile behavior of FRCM composites provides the parameters needed for the design of the structural reinforcement and has given rise to numerous research studies on the aspects that influence its mechanical properties. To obtain the tensile behavior characteristics of this composite under different boundary conditions, two test setups were investigated. A clevis grip (pin action) was used to reproduce field boundary conditions from typical installation and to obtain design parameters. A clamping grip was used to obtain a complete characterization of the composite by inducing a tensile failure of each constituent material. Several FRCM systems made with different fabrics were used for the investigation: polyparaphenylene benzobisoxazole (PBO), carbon (C), and glass (G), plus carbon and glass with a special protective coating. This paper offers a critical analysis of the experimental results and provides recommendations for the tensile characterization of FRCM materials

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Composite materials made with textile fibers both with polymeric and cementitious matrices are often adopted for the retrofitting of masonry arches and vaults. A specific project that analyzes the performance of ancient masonry arches and vaults strengthened with composite systems has been recently concluded at Politecnico of Milan. The project involves the experimental evaluation and the development of numerical and analytical simulations. In this paper the experimental campaign is described, whereas the numerical validation is provided in an accompanying paper [1]. The tests were performed in-situ on ancient masonry arches and vault elements. In particular, three barrel vaults and two arches either unreinforced or reinforced with Steel Reinforced Grout (SRG), Textile Reinforced Mortar (TRM) and Fiber Reinforced Polymer (FRP) were tested. The arches had a span equal to 3.30 m, a rise equal to 0.83 m and were built with common Italian bricks regularly spacing out two bricks laid edge on (thickness of the arch 12 cm) with two bricks (one over the other) disposed in single leaf. Barrel vaults had the same geometry of the arches but were made with a single leaf. In all cases, an eccentric vertical load was applied at ¼ of the span and was increased up to failure. The experimental results on unreinforced structures are compared with those obtained on the strengthening ones in terms of failure mode, maximum load, stiffness and ductility.