Effects of Rust and Scale of Reinforcing Bars on the Bond Performance of Reinforcement Concrete: Fid-Bau Portal

Effects of Rust and Scale of Reinforcing Bars on the Bond Performance of Reinforcement Concrete

Huang, Chung-Ho

To investigate the effect of reinforcement corrosion on the bond properties between concrete and reinforcing steel bar, pullout tests were conducted on a total of 20 specimens using corroded reinforcement bars embedded in concrete specimens. No. 3 (9.5-mm diameter) and No. 6 (19-mm diameter) bars corroded by an accelerated corrosion method were selected for testing. Two groups of corrosion specimens were prepared: one was whole-surface corroded (100%), and the other was partial-surface corroded with 40, 60, and 100% corrosion. Each group of specimens included four levels of corrosion: 3, 5, 10, and 15%. Results indicate that the tensile strength of steel bar decreases with the increase of corrosion level. Corrosion levels less than 3% present a minor tensile-strength reduction of approximately 3%, whereas the tensile strength may decrease to 75–90% when the corrosion level increases more than 10%. The critical bond strength and ultimate bond strength of corroded bars may increase slightly with corrosion level less than 3%, but tend to decrease as the corrosion level exceeds 3% and, likewise, to decrease with increasing corroded-surface percentage of steel bar. The range of partial-surface corrosion shows no significant effect on yield strength and ultimate strength of the steel bar. However, the critical bond strength and ultimate bond strength in a reinforcing steel bar decrease with the percentage of corroded surface for various corrosion levels when the corroded area increases from 40–100%.