Verification of a rapid technique for corrosion measurement using reinforced concrete slabs after long-term field exposure

Paper i proceeding, 2007

This paper presents the results from the measurement of reinforcement corrosion in slabs after over 13 years’ exposure in the marine environment, using a newly developed rapid nondestructive technique. In the beginning of 1990’s over 40 reinforced concrete slabs with different types of binder and water-binder ratios were exposed in a real marine environment at Swedish west coast. In the past years a rapid technique for non-destructive measurement of corrosion was developed at SP Technical Research Institute of Sweden. The technique is based on the classic galvanostatic pulse technique with the time-dependent behaviour of polarisation taken into account and the mathematical modelling for estimation of current distribution. The technique was implemented into a handheld instrument for easy use in the field. This instrument was used to measure the corrosion conditions of the steel bars embedded in the concrete slabs exposed in the field site. Based on the results from the nondestructive measurement, the actual corrosion of steel bars in five concrete slabs was visually examined. The results from the visual examination show that the newly developed rapid technique is a useful tool with reasonably good accuracy for assessment of corrosion of steel in concrete. It has been found that the corrosion rate measurement is the most reliable parameter, while the half-cell potential and resistivity can only be used as complementary parameters in the assessment of corrosion status.