A methodology for the evaluation of morphology-based constitutive laws of corroded steel rebars

The assessment of degraded reinforced concrete (RC) existing structures is nowadays a topical problem since several ones have an age close to or higher than their design life. The degradation state of the structure needs to be properly assessed and included in the adopted numerical or analytical models. In this framework, rebars corrosion phenomena can modify the structural behavior of RC members, especially when the corrosive attack is localized in specific areas. As an example, in presence of localized concentrations of chlorides, pitting corrosion of the steel bars occurs, with a localized reduction of the bar section through pits. In this work, the results of a preliminary experimental survey performed on artificially corroded steel rebars are shown, to define an integrated methodology for the definition of material constitutive laws, accounting for morphological aspects of the corrosion phenomenon. A set of steel rebars, embedded in concrete prisms, have been artificially corroded with an accelerated process through electrolytic cells, to obtain local marked pits. The steel rebars have been extracted, cleaned, weighed and subjected to 3D scanning using two different techniques (one based on laser scanning and the other based on structured-light scanning) to evaluate the effective corrosion amount and morphology. Finally, tensile tests were carried out to evaluate the stress-strain curves and the values of yielding, ultimate strengths and elongation to fracture. The presented data and methodology can represent a useful reference for the definition of phenomenological constitutive laws for steel rebars affected by pitting corrosion.