Influence of Acceleration Approaches on the Corrosion Behavior of Embedded Steel in Mortar

In this article, the influence of three acceleration approaches (electrochemical corrosion method, alternate wetting and drying method, and salt spray method) on the corrosion behavior of a steel bar embedded in mortar cover was investigated. The steel corrosion and the mortar cracking were characterized by using an X-ray microcomputed tomography (μCT) and scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS) techniques. The results showed that the cracking time of mortar was the longest in the salt spray method (approximately 384 days), followed by the alternate wetting and drying method (approximately 269 days), and the electrochemical corrosion method (approximately 66 days). For similar maximum width of cracks on the surface of concrete cover, the electrochemical method generally resulted in a higher level of corrosion in reinforcement than the other two methods. The corrosion products of steel and the distribution of crack patterns obtained from the salt spray method were more nonuniformly distributed than the ones obtained from alternate wetting and drying method whereas those formed via the electrochemical method had a uniform distribution. The aforementioned findings are also valid for the distribution of crack patterns. In terms of the composition of corrosion products, the value of the atomic ratio of iron to oxygen (Fe/O) in the wetting and drying and salt spray methods was smaller than that obtained in the electrochemical method because the specimens under the former two methods were exposed to air for a much longer period of time than in the electrochemical method.