An Investigation of the Debonding Mechanism between FRCM Composites and a Masonry Substrate

Fiber reinforced cementitious matrix (FRCM) composites have recently become a hot topic in Europe as an alternative to traditional fiber reinforced polymer (FRP) composites for several strengthening applications of existing masonry buildings. The terrific success of this new retrofitting system is mainly due to some advantages that it offers when compared to FRP, such as the possibility of application of the composite to wet surfaces and the vapor permeability featured by the inorganic matrix. In this work, the stress transfer between FRCM composites and a masonry substrate is investigated. FRCM strips comprised of ultra-high-strength steel fibers embedded in a cementitious grout are externally bonded to masonry blocks. Single-lap direct shear tests are performed. Parameters studied are bonded length and density of the steel fibers. Load responses are presented and failure modes are discussed. Change in the bond behavior and load carrying capacity with increasing bonded length is analyzed to determine the effective bond length.