Experimental characterization of the textile-to-mortar bond through distributed optical sensors

TRM (Textile Reinforced Mortar) and FRCM (Fiber Reinforced Cementitious Mortar) strengthening materials are highly heterogeneous composites involving domains that have dramatically different mechanical properties (i.e., inorganic matrix and fabric textile). Maximizing their exploitation ratio involves achieving a better bond be- tween textile and inorganic matrix which shifts the failure mode from textile sliding to textile rupture or cohesive failure modes. So far, the local bond behaviour between fiber bundles and inorganic matrix has been analysed indirectly through the evaluation of the global performance of TRM/FRCM materials subjected to tensile tests or single lap shear tests. In this article, the authors adopted distributed fiber optic sensors directly installed to textile bundles to track the strain evolutions of PBO-TRM strengthening materials. The strain evolutions were used, for the first time, (i) to understand the behaviour of TRM coupons subjected to tensile tests and (ii) to experimentally calibrate the interfacial tangential bond-slip law in flat masonry pillars strengthened with TRMs. The results allowed a better insight of the response of TRM materials not possible with traditional sensors and an accurate characterization of their bond performance. The interfacial tangential stress-slip law was then adopted in analytical models to predict the global performance of TRM materials providing satisfactory results compared with experimental outcomes.