Repair of shear-deficient and sulfate-damaged reinforced concrete beams using FRP composites

Reinforced concrete structures often demonstrate nonstructural cracking caused by the action of sulfates from external sources. These cracks are signs of concrete damage that reduces the flexural and shear capacity of reinforced concrete structural elements and require therefore immediate attention. In this paper, the potential of using advanced composite materials in repairing shear deficient reinforced concrete prototype beams that are damaged by a sulfate cyclic treatment to a predetermined level is investigated. Prototype sulfate-damaged beams were repaired using varying configurations of (carbon and glass) fiber reinforced polymer (FRP) sheets or strips. Experimental data on shear strength capacity, stiffness, deflection, FRP strain, crack opening and mode of failure of the repaired beams were obtained, and compared with those of control, and sulfate-damaged ones. The results confirmed that FRP composites applied to shear spans not only enhanced the shear capacity but also improved deflection characteristics, stiffness, toughness, profitability index, crack resistance, performance factor, and FRP composites strain. However, the effectiveness of the present FRP repair schemes in terms of load capacity was negatively affected by the level of sulfate damage. Finally, a suitable analytical model was developed and examined for the prediction of FRP contribution to shear capacity of sulfate-damaged beams.