Probabilistic Modeling of the Relationship between Concrete Crack Width and Corrosion-Induced Mass Loss of Steel Bar

Corrosion-induced concrete cover cracking generally experiences two stages: initial stage when cracks are developed from the bar until reaching the concrete surface; propagation stage in which cracks connect and widen on the concrete surface. A lot of studies have been conducted to investigate corrosion-induced concrete cracking. However, most of them are focused on the initiation stage and less work are done in the propagation stage, particularly on the relation between the crack width and the cross-sectional area loss of steel bars. The relation between the concrete crack width and the area loss of steel bar is not deterministic, due to the variation of environmental parameters such as temperature, moisture, availability of oxygen, and the non-homogeneity of concrete cover, passive film, and metallurgical properties of steel bars. Therefore, probabilistic method will be more realistic than the deterministic approaches. In this study, the relation between concrete crack width and corrosion-induced mass loss of steel bar was studied in a probabilistic way. Concrete block specimens containing steel bars were prepared and subjected to accelerated corrosion test (ACT). Three concrete cover thicknesses were considered including 25.4 mm, 50.8 mm and 63.5 mm. The ACTs are terminated when the corrosion of steel bar reached to different levels ranging from 0% to 30% mass loss. The crack width is measured using a crack meter and the residual area of corroded steel bars is determined with a 3D laser scan. For a fixed corrosion loss, the corresponding crack width was fitted with a probabilistic density function (PDF). Probabilistic analysis results showed that normal distribution function best fitted the distribution of crack width. The mean crack width increases logarithmically with an increase in the corrosion-induced area loss of steel bars.