An experimental investigation on the corrosion resistance and bond behaviour of concrete reinforced with stainless steel and carbon steel bars – a comparative study

This study aimed to investigate the corrosion rate, corrosion resistance, and bond behaviour of stainless steel (SS) bars in comparison to carbon steel (CS) bars. Concrete specimens (M30) were cast using SS (grade SS550) and CS (grade Fe550D) bars and then immersed in NaCl medium with varying concentrations (0%, 3%, and 5%). Accelerated corrosion and pull-out tests were conducted to determine the corrosion resistance and bond behaviour of the concrete, while the Natural Corrosion Rate test was performed to determine the corrosion rate. The test results revealed that CS bars failed three times faster than SS bars and exhibited a corrosion rate approximately 6 times higher than SS bars. Furthermore, the limit of corrosion initiation and propagation ratios for CS vs. SS rebar was found to be 1:1.8 weeks and 1:1.7 weeks respectively. Consequently, the bond strength of CS bars after corrosion was found to be 30% lower than that of SS bars. SEM analysis indicated that the presence of a chromium oxide film on SS steel exhibited better protective properties than that of CS steel. The chloride threshold value measured by using potentiometric titration showed that SS bars had a higher resistance against the chloride penetration approximately two times higher than that of CS bars. From this experimental study, it can be concluded that corrosion resistance, bond behaviour, protective properties and service life of SS steel bars suggest its potential superiority over CS steel bars in concrete structures.