Mechanical properties and debonding strength of Fabric Reinforced Cementitious Matrix (FRCM) systems for masonry strengthening

Fabric 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. (C) 2014 Elsevier Ltd. All rights reserved.