Effects of bleeding on corrosion of horizontal steel bars in reinforced concrete column specimen

Abstract

The durability of reinforced concrete proved to be predominantly controlled by the resistance against ingress of harmful substances including chloride ions, carbon dioxide, and moisture. The corrosion of steel bars taking place especially in a marine environment was likely to be severe, which depends on the availability of oxygen and moisture consumed by cathodic reactions. This study aims to investigate the effects of bleeding on the corrosion of horizontal steel bars placed in reinforced concrete column specimens. This was examined through electro-chemical tests including the half-cell potential, polarization resistance, and corrosion current density carried out using specimens in which corrosion was induced via dry and wet (NaCl 10%) cycles. The presence or absence of copper slag fine aggregate and fly ash replacement were taken up as experimental factors. The results suggested that the corrosion of horizontal steel bars in the upper part of the column concrete specimen was adversely affected even for the case of OPC specimens with relatively lower bleeding water. This was attributed to less resistance against the ingress of corrosive substances especially in those locations. In the case of fly ash mixtures, the corrosion resistance was significantly improved owing to lower oxygen permeability measured via cathodic polarization technique.