Bond behaviour of naturally corroded plain bars in reinforced concrete structures.

Reinforced Concrete is known to be susceptible to corrosion damage. Corrosion, by reducing strength and ductility of the reinforcing bar and modifying the steel/concrete interface, hinders the overall safety of the structure. This work investigates the bond of naturally corroded, plain reinforcing bars. Specimens were taken from an 80-year-old bridge and tested using pull-out and 3-point bending tests. Additionally, neutron and X-ray tomography is used to observe the distribution of corrosion products. Results highlight the influence of casting position on the bond of plain bars. Specifically, the distribution of corrosion products is influenced by the bleeding zone underneath top-cast bars. Corrosion products are shown to deposit in macro-pores and to adhere to the bar