Abstract
Hot dip galvanizing technology is now widely used as a method of protection for steel rebars. The corrosion behaviors of Q235 carbon steel and hot galvanized steel in a Ca(OH) 2 solution with a pH from 10 to 13 was investigated by electrode potential and polarization curves testing. The results indicated that carbon steel and hot galvanized steel were all passivated in a strong alkaline solution. The electrode potential of hot dip galvanized steel was lower than that of carbon steel; thus, hot dip galvanized steel can provide very good anodic protection for carbon steel. However, when the pH value reached 12.5, a polarity reversal occurred under the condition of a certain potential. Hot dip galvanized coating became a cathode, and the corrosion of carbon steel accelerated. The electrochemical behaviors and passivation abilities of hot dip galvanized steel and carbon steel were affected by pH. The higher the pH value was, the more easily they were passivated. DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16675
Highlights
Reinforcement concrete is widely used in modern architecture
The aim of this work is to study the protective effect of hot dip galvanizing on carbon steel and the corrosion behavior of carbon steel as well as hot dip galvanized steel in a Ca(OH)2 simulated solution with a pH from 10 to 13, through analysis of open-circuit potential (OCP) and polarization curves
The OCP data was recorded for 3600 s at a rate of 10 s after working electrode samples were immersed in simulated concrete pore (SCP) solutions of pH 10, 11, 12, 12.5, and 13 successively [15]
Summary
Reinforcement concrete is widely used in modern architecture. it is being found that reinforced concrete structures lose efficiency too quickly, especially in corrosion media or dry-wet-cycle conditions, which can cause serious losses. Concrete has pores in it, and in the early stage, the main ingredient of a concrete pore solution is a saturated Ca(OH) solution, and steel has a compact passivated layer. A neutralization reaction occurs when CO2 passed capillary pores of concrete are combined with Ca(OH) in the concrete pore solution, which creates CaCO3. This whole process is referred to as carbonation. The pH of the concrete pore solution changes, which influences passive film formation on steel bars. This result increases the possibility of reinforcement corrosion
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