Determination of loss of reinforcement due to corrosion through X-ray computer micro-tomography

Abstract

X-ray computer scanning tomography (CT scan) is an increasingly more available technique, which has been applied to material sciences for years. Although most of its use is qualitative for gaining insights on material behavior, quantitative analysis for estimations of deterioration rates is possible. This paper describes an unbiased, straightforward method to determine the amount of reinforcement lost to corrosion through the use of X-ray tomography without the need to remove the concrete cover. Other methods of assessment such as gravimetric analysis, half-cell potential, resistivity of mortar cover, corrosion current, and scanning electron microscopy (SEM) are used in the same samples for comparison. While the electrical and electrochemical tests are valuable to describe the state of the samples, those demonstrated poor capacity of determining the stage of corrosion of the reinforcement in terms of amount of material lost. Electron microscopy could determine how much of the reinforcement corroded with high accuracy; however, these results are deficient in representativity, being based on a single plane of the steel. X-ray tomography, while suffering from sample size limitation, could provide quantitative information on the total volume of material lost for each sample with far higher accuracy than indirect techniques, which is significant for the forensic determination of remaining life service of structures.