Flexural behavior of corroded one-way slabs strengthened with CFRP in two different techniques

The experimental investigation conducted in this paper investigates the flexural behavior of corrosion-damaged reinforced concrete (RC) slabs reinforced with carbon fiber-reinforced polymer (CFRP) using two different techniques, namely NSM with CFRP ropes and CFRP strips. The steel reinforcing bars of the examined slabs underwent corrosion induction using an accelerated corrosion approach. This study included three groups of corroded slabs (weak, moderate, and sever corrosion), two models in each group that were strengthened using CFRP in two different ways, with a reference model in each group. Weight loss percentages for each corrosion level is were 11%, 26%, and 40%, respectively. The result showed that not only the yielding and ultimate capacities of the reinforced slabs were recovered, but they also outperformed those of the virgin control slab. Slab strengthened with CFRP strips showed an increased in yielding strength from 15 to 65%, 20–53%, and 38–58% for 10,17, and 24 days, respectively. Also, for NSM, an increase in the yield strength from 15 to 38% and from 20 to 23% was recorded. While, for the 40% corrosion a clear reduction in the yield strength was recorded due to losing a third of the depth of the section due to the effect of steel corrosion as well as losing some of the steel cross-sectional area. Results show that increasing corrosion levels from 11 to 42%, reduce the strengthening of the load capacity of the slab to the applied loads from 38 to 15%. It is worth mentioning that the examined reinforced slabs were failed due to both yielding in the steel reinforcing bars as well as compression crushing of the concrete.