Applications of a rapid non-destructive technique in assessment of corrosion conditions of steel in reinforced concrete structures

This paper presents some applications of a rapid technique for non-destructive assessment of corrosion conditions of steel in reinforced concrete structures. The technique involves a short time galvanostatic pulse measurement followed with the numerical calculation for correcting the preset polarisation current from the measured ohmic and polarised potential responses, so as to be able to estimate the “true” values of ohmic and polarisation resistances related to the confined area. Owing to its rapidity (in a few seconds per measurement), this technique provides a useful tool for mapping electrochemical characteristics of reinforcement steel in concrete structures, including half-cell potential, ohmic resistivity and corrosion rate. These three corrosion-related parameters supply better information to an inspector for condition assessment of reinforced concrete structures. It has been shown from a number of case applications that the measured corrosion rate is in good agreement with the actual visual observations, while the half-cell potential sometimes may mislead the judgement. Even though the resistivity of concrete alone cannot tell much information about reinforcement corrosion, it indeed supplies some information that can help the judgement of corrosion conditions when used together with the measurement of corrosion rate