Corrosion behaviour of carbon steel and corrosion resistant steel under elevated temperature and chloride concentration in simulated concrete pore solution

摘要

Corrosion of reinforcing steel in marine environment is a major durability problem in reinforced concrete structures. This problem is exacerbated under hot weather conditions. Specialty steel bars are used in place of conventional carbon steel (CS) bars to avoid corrosion problems in severe environments. This article reports the corrosion-resistance behaviour of carbon and two specialty steel bars under varying chloride concentration (500, 1000 and 2000 mg/L) and temperature (25 and 55 degrees C). The corrosion resistance of CS and specialty bars was evaluated using linear polarization resistance and potentiodynamic polarization techniques. The morphology of the exposed specimens was evaluated using a scanning electron microscope coupled with energy dispersive spectroscope. The corrosion rate increased as the exposure temperature was increased from 25 to 55 degrees C. Uniform corrosion was noted on the specimens exposed to low temperature (25 degrees C) while pitting corrosion was noted on those exposed to elevated temperature (55 degrees C). Both uniform and pitting corrosion was noted, at both the exposure temperatures, on alloying/microstructure (A/M) steel while marginal pitting corrosion was noted on stainless steel (SS) specimens exposed to 55 degrees C. Polarization data indicated enhanced corrosion resistance of A/M and SS under hot chloride environments compared to CS bars.