Corrosion attack in existing reinforced concrete structures: in-field investigation and analysis of naturally corroded bars

Corrosion of steel bars is a major issue for the management of existing reinforced concrete structures, since affecting many ageing structures and infrastructures and introducing risk for safety and reliability, as well as high maintenance costs. Intervention strategies should be planned and carried out according to the effective state of deterioration and to the expected evolution of performances over time. The critical parameters needed to evaluate these performances are the intensity and pattern of the corrosion attack, referring to both extension and depth of the attack. However, this information is rarely available and hard to predict when dealing with real structures. This paper presents a field investigation on existing corroded structures characterized by different environmental conditions. Corroded bars were removed from structural elements, the corrosion patterns were studied, and then the bars were tested to determine their mechanical properties. The objective of this study is to increase the knowledge of the effects of corrosion in natural environments and to propose a method to relate easy-measurable environmental conditions with the characteristics of the expected corrosion attack, which need to be further validated.