Durability and strength characteristics of NSM–GFRP rods retrofitted corrosion–damaged RC beams: experimental and analytical approach

Despite the tremendous research conducted to explore the near-surface-mounted (NSM) with fibre-reinforced polymer (FRP) strengthening systems, there is a dearth of studies on using glass FRP (GFRP) rods as a cost-effective alternative to carbon FRP. In this study, the technical feasibility of using the NSM-GFRP technique for the rehabilitation of corroded reinforced concrete beams is evaluated. Investigated variables include flexural stiffness, yielding, ultimate strength capacity, ductility, mode of failure and durability of the employed repairing system under further corrosion conditions. Two different degrees of acceleration corrosion process, 10 and 30%, were applied in the initial stage and upon the RC beam strengthened with the GFRP system. The experimental results showed that strengthening the corroded beams with NSM-GFRP improved their stiffness, ductility and flexural resistance at all loading stages. At the post-cracking stage, however, both reinforcements, NSM-GFRP and corroded steel bars, contributed complementarily to resisting the applied loads. Upon specimen ageing with an additional corrosion phase, the strengthening system used maintained its efficiency in restoring beams’ strength, ductility and energy absorption capacity, regardless of the initial mass loss that occurred. The ACI 440.2 provisions predicted the peak strengths of the strengthened beams reasonably well with conservative estimations.