Durability study on reinforced concrete axial members retrofitted with fibre-reinforced cementitious matrix (FRCM)**********

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Fabric-reinforced cementitious matrix (FRCM) is a retrofitting system that has been introduced recently to retrofit/strengthen reinforced concrete (RC) structures. FRCM consists of one or more layers of anti-corrosive textiles made of carbon, glass, or Polyparaphenylene benzobisoxazole (PBO) grids that are sandwiched between layers of cementitious mortars. Unlike the epoxy-based fiber-reinforced polymers, mortars used in FRCM systems inherit the compatibility between the system and the concrete substrate since both materials have the cement as a common "base". To date, no data is available on the aging performance of FRCM-wrapped RC elements under the combined effect of axial loading and the exposure to harsh environmental conditions. The proposed research aims at examining such performance through a series of laboratory tests that will be conducted on RC prisms and cylinders wrapped with FRCM and tested under axial loads. The test parameters include the specimen's cross section (square and circular), the type of FRCM systems (2 types), the number of FRCM layers (1 or 2 layers), the specimen's condition prior to wrapping (conditioned or unconditioned), and the exposure condition after wrapping, which include (1) freeze-and-thaw cycles, (2) high temperatures, (3) humidity and high temperatures, (4) alkali solution, and (5) saltwater. Unconditioned specimens will be tested for reference. Specimens will be instrumented with strain gauges and/or compressometers to monitor the loads and strains during the test until failure occurs. Experimental results in terms of capacity, debonding, straining, modulus, and ductility will be recorded. The effect of different exposures on such quantities will be determined and verified against the provisions of ACI-549.4R-13. The results would be used to develop conceptual design rules for FRCM systems, which consider the effect of environmental aging in RC compression members such as columns and walls.