Corrosion Susceptibility of Blued Steel Reinforcement in Concrete by Electrochemical Impedance Spectroscopy

Abstract

The main aim of this study is to quantify the rate of corrosion in reinforced steel bars embedded within concrete structures exposed to a simulated high-chloride marine environment. This involved selecting specific frequencies that corresponded to the solution resistance and charge transfer resistance, enabling faster measurements. A total of five cement mortar specimens were meticulously prepared for the investigation. The study focused on assessing the impact of variations in bluing temperature on corrosion minimization. Bluing was carried out at 450, 550, 650, and 750oC, and then immersing the specimens in a 3 wt.% NaCl solution for 21 days. Frequent tests, just after immersion, 7,14-, and 21-days immersions. Measurements through alternative current (AC) impedance were conducted across a frequency spectrum ranging from 100kHz to 10MHz. The results showed a significant decrease in the corrosion rate for specimens blued at 750, which was attributed to the development of thicker protective layers on the rebar. Higher corrosion rates were observed for bluing at lower temperatures.