Confinement of Damaged and Nondamaged Structural Concrete with FRP and TRC Sleeves

The potential for using textiles impregnated with cement as a means for in situ strengthening and retrofit of structural concrete was explored and compared with the conventional epoxy method. Fabrics of different geometries, yarns, and modulus values were evaluated. Simulation of repair and strengthening was carried out by wrapping fabric impregnated with cement and epoxy around damaged and undamaged concrete cylinders. The cylinders with the impregnated sleeves were loaded in compression, and their performance was compared with that of the “virgin” (control) concrete. In addition, the mechanical properties of the cement composite layer were evaluated, as well as the stiffness of the fabrics themselves, and correlated with that of the repaired system. Efficient repair with the cement binder was accomplished with the high modulus fabric (Kevlar) in particular. However, even the lower modulus (polypropylene) could be effective in repairing and inducing some postpeak resistance (although to a smaller extent than with the Kevlar). Improved behavior was also obtained with the nondamaged concrete cylinder when it was strengthened with the cement–fabric jacket, mainly at composite strain values of up to 0.2–0.3%.