The role of mortar matrix in the bond behavior and salt crystallization resistance of FRCM applied to masonry

Fiber-reinforced cementitious matrix (FRCM) composites are a new category of composites recently proposed for seismic strengthening of historical masonry structures, to provide a more compatible solution compared with fiber-reinforced polymer (FRP) composites. Despite the rapidly increasing number of research papers dealing with the mechanical behavior of FRCM composites applied to masonry, their long-term performance and susceptibility to weathering processes are still largely unexplored. In this paper, the response of FRCM-masonry joints to accelerated weathering is investigated. A laboratory testing procedure, previously developed by the authors, which involves wetting-drying cycles in water and saline solutions, is employed. Two different types of mortars (based on natural hydraulic lime and Portland cement) were used for the composite matrix, without changing the geometry, the type of masonry substrate and the fibers (galvanized steel cords), in order to assess the role of the matrix in the FRCM-masonry joint bond behavior and deterioration processes. Results show that the matrix played a key role in the debonding mechanism of the FRCM-masonry joints as well as in the capillary absorption of water and in the resulting salt crystallization patterns. (C) 2019 Elsevier Ltd. All rights reserved.