Comparison of In-Situ Monitoring Methods for Soil Corrosion of Grounding Galvanized Round Steel

The corrosion behavior of grounding galvanized round steel buried in soil environment of Wuhan was studied by weight loss method, guard ring electrode method and electrochemical impedance method, and the correlation of the monitoring techniques was compared. The results showed that the corrosion rate of the sample was large when buried for 1-2 months, and then gradually decreased. The dissolution of the zinc coating was uneven, and there was little residual zinc coating on the sample surface after 3 months of burial. The polarization resistance measured by electrochemical impedance method displayed a good correlation with corrosion rate. However, due to the influence of the galvanic couple between zinc coating and Q235 steel substrate, the corrosion rate cannot be directly calculated using traditional method. Under appropriate conditions, the polarization resistance obtained by guard ring electrode method could be comparable to that measured with electrochemical impedance method.