Analysis of the bond between Fabric Reinforced Cementitious Mortar (FRCM) strengthening systems and concrete

The paper is devoted to the analysis,both experimental and theoretical, of the bond between a cement based fiber reinforced strengthening material and the concrete substrate. Results of tests on concrete specimens strengthened with the PBO-FRCM system, made by PBO (short of Polypara-phenilene-benzo-bisthiazole) fiber meshes embedded into a cementitious mortar (FRCM, Fabric Reinforced Cementitious Mortar), are presented and discussed. Tests were carried out varying both the bond length, the amount of the strengthening system and the service temperature. Obtained results furnish useful information (i) to determine the loss of bond between the PBO-FRCM system and the concrete, (ii) to define the failure modes and (iii) to evaluate both the influence of environmental conditions (service temperature) and mechanical and geometrical parameters on the loss of bond PBO-FRCM-to-concrete. Test results were, then, utilized to calibrate a local bond-slip relation. A comparison between experimental results and theoretical predictions of the bond-slip law PBO-FRCM-to-concrete is, finslly, presented and discussed.