A Rapid Technique Using Handheld Instrument for Mapping Corrosion of Steel in Reinforced Concrete
Journal article, 2006
This paper presents a rapid technique using a handheld instrument for mapping corrosion of steel in reinforced concrete structures. The technique involves a short time galvanostatic pulse measurement followed with the numerical calculation of the effective polarization current from the measured ohmic and polarized potential responses, so as to be able to estimate the true values of ohmic and polarization 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. The results from comparative measurements on both small and large reinforced concrete slabs show that the corrosion rate measured by the new developed rapid technique is quite comparable with that measured by the Spanish Gecor instrument, which uses the modulated confinement technique. The technique has been used in a number of real concrete structures. The results show that the corrosion extent measured by the new rapid technique is in reasonably good agreement with those by the other techniques and visual observations.