Effects of rising damp and salt crystallization cycles in FRCM-masonry interfacial debonding: Towards an accelerated laboratory test method

Fiber-reinforced composites with inorganic matrix (FRCMs) have been recently proposed as a more compatible and durable route to strengthen masonry structures with respect to FRPs (fiber-reinforced polymers), but their weathering mechanisms in aggressive environments are still scarcely known. In this paper, brick masonry specimens were reinforced with FRCM strips, made of galvanized steel fibers embedded within a hydraulic lime-based mortar, and were subjected to an artificial weathering procedure designed by the authors, involving capillary water absorption and salt crystallization cycles. Finally, direct shear tests were performed on the FRCM-masonry joints. To reproduce conditions that may be found in real buildings, shear tests were also carried out after applying the FRCM composite on salt laden masonry blocks. Interfacial debonding behavior was interpreted based on the salt distribution within the masonry joints and the porosity of materials. The permeable matrix did not hinder the migration of the saline solution used in some cycles, which in turn resulted in no significant accumulation of salts beneath the composite strip, and no micro-crack opening in the composite after accelerated weathering. Some corrosion of the galvanized steel cords in presence of high amount of chlorides was observed in the composite.