The simultaneous impact of corrosion and the reinforcement ratio on the load-bearing capacity of reinforced concrete under axial compression

Introduction. This study presents the results of an experimental assessment of the simultaneous impact of corrosion and the reinforcement ratio on the load-bearing capacity of standard reinforced concrete elements subjected to axial compression. Materials and methods. This study was conducted using 216 experimental specimens made of ordinary concrete longitudinally reinforced by high bond reinforcing steel FeE400. The cross-sectional dimension of our experimental reinforced concrete specimens was 20 × 20 cm, and their height was 32 cm. Six cases of bond strength degradation were considered in percent: 0, 20, 40, 60, 80 and 100 %. Experimental specimens had four diameters (Ø). Reinforcing steel rods had the following diameters: Ø10, Ø12, Ø14 and Ø16. For each bond degradation strength value, nine specimens were made using 4Ø10, 4Ø12, 4Ø14 and 4Ø16 rods. The longitudinal steel reinforcement had the reinforcement ratio of 0.80, 1.13, 1.54 and 2.01 %. Bond strength degradation was simulated by applying adhesive tape to the contour surface of the steel rods to prevent the adhesion between the reinforcement and the concrete, in compliance with the required extent of bond strength degradation. The experimental reinforced concrete specimens were subjected to axial compression 28 days later. The collapsing forces, thus obtained, were transformed in compressive strength for the purpose of analysis and interpretation of the results. Results. For one and the same reinforcement ratio, the loss of the load-bearing capacity of reinforced concrete increases, as bond strength degradation goes up. For the same bond strength degradation, the loss of the load-bearing capacity of reinforced concrete also increases, if the reinforcement ratio goes up. Bond strength degradation from 0 to 100 % leads to the load-bearing capacity loss to 11.62, 16.52, 21.32, 26.26 % respectively for the reinforcement ratio μ of 0.80, 1.13, 1.54 and 2.01 %. The curves, demonstrating the load-bearing capacity loss by the reinforced concrete subjected to axial compression, are presented as functions that depend on bond strength degradation and the reinforcement ratio. Conclusions. Bond strength degradation from 0 to 100 % leads to the load-bearing capacity in the range of 11.62 to 26.26 % for the reinforcement ratios between 0.80 and 2.01 %, respectively. The load-bearing capacity loss by reinforced concrete elements subjected to axial compression is presented as the function depending simultaneously on bond strength degradation and the reinforcement ratio. Evidently, excessive reinforcement will negatively affect the durability of the reinforced concrete element under axial compression. Over-reinforced concrete elements under axial compression will be less durable compared to normally reinforced ones.