Experimental and analytical investigation on the use of NSM-BFRP and NSM-GFRP bars in strengthening corrosion-damaged RC slabs

This paper presents the results of an experimental and analytical study on the flexural behavior of corrosion-damaged reinforced concrete (RC) slabs strengthened with different near-surface mounted fiber-reinforced polymer (NSM-FRP) bars. An accelerated corrosion technique was used to induce corrosion in the steel reinforcing bars of the tested slabs. The investigated parameters comprised the number of NSM-FRP bars (two and four bars), the type of the NSM-FRP reinforcement (basalt B and glass G bars), and the mass loss in the steel rebars due to corrosion (10 and 20%). The yielding and ultimate capacity of the strengthened slabs was not only restored but surpassed those of the virgin control slab. Slabs strengthened with two and four NSM-BFRP bars showed 32-42% increase in their yielding load and 45-50% in their ultimate loads, respectively, as compared to the unstrengthened corroded slab. Similarly, the strengthened slabs showed 5-50% increase in their ductility index as compared to the virgin slab. The strengthened slabs failed due to the yielding of the steel reinforcing bars followed by compression concrete crushing. ACI-440 formulations reasonably predicted the performance of the strengthened slabs with conservative capacities when ACI strain limit of 0.7 & epsilon;fu was considered.