Study on corrosion characteristics of steel rebars and corrosion-induced cracks in reinforced concrete by employing X-ray microcomputed tomography

Abstract

The aim of this study was to use X-ray microcomputed tomography (X-μCT) method to analyze the corrosion characteristics of steel rebars and corrosion-induced cracks in reinforced concrete. This non-destructive method was used for the qualitative observation (2D/3D information) and quantitative measurements of volumes of steel rebars, corrosion products and corrosion-induced cracks, which were affected by accelerated-corrosion durations and inhibitors (inorganic inhibitor NaNO<inf>2</inf> and organic inhibitor DEA (C<inf>4</inf>H<inf>11</inf>NO<inf>2</inf>)). For all corrosion durations, the volumetric change rates of corrosion products and corrosion-induced cracks showed strong linear relationships, as the slope values, i.e., the volumetric change rate ratios of corrosion-induced cracks and corrosion products for different inhibitor systems were all close to 1.7 in all linear regression models. Further, a new technique of measurement of the corrosion-inhibition efficiency for steel rebar by using the X-μCT method was developed on the basis of experimental research results. The obtained experimental laws and proposed technique enable the prediction and impart a better understanding of the corrosion behavior in reinforced concrete. In addition, electrochemical impedance spectroscopy (EIS) and Raman spectroscopy measurements were also used to support the results of X-μCT analysis.