Carbon fiber reinforced polymer (CFRP) inserted in different configurations of the tensile zone retrofitting with microconcrete containing steel fibers to the strengthening of beams

It is researched, in this study, the strengthening technique known as Near Surface Mounted (NSM), which consists of the insertion of laminates of Carbon Fiber Reinforced Polymer (CFRP) into notches in the covering concrete structures. In the strengthening in beams, the tensile zone is found damaged for several reasons (cracking and corrosion, for instance), which demands, in the practice of engineering, its preliminary retrofitting. It should be considered that the good performance of the material used in this retrofitting is fundamental for a higher efficiency of the strengthening. Therefore, it is proposed a methodology that consists of the reconstitution of the tensile zone of the beams with a cement-based composite of high performance (CCAD), which acts as a substrate for the application of CFRP and as an element for the transfer of efforts to the part strengthened. The retrofitting of this tensile zone was performed only in the shear span, as well as throughout of the zone with a view to evaluating the influence of this aspect on the performance of the beams. The CCAD, produced from Portland cement, steel fibers and microfibers, was evaluated using the Rilem (2002), showed to be able to delay the cracking. Tests performed in the beams with the tensile zone retrofitting by CCAD and strengthening using the technique NSM showed the efficiency of the proposed methodology.