Experimental tests on bond performance between corroded steel reinforcements and concrete

The corrosion of steel bars in concrete is a dangerous and extremely costly problem, that causes losses of serviceability and structural capacity in buildings and bridges. Once that the depassivation occurs, as a result of concrete carbonation or chlorides attack, at the steel-concrete interface the iron oxides expand approximately 2–6 times in volume, causing cracks and bond-slip degradation. In particular, the reinforcement - concrete bond degradation, influences the deformability of the element and consequently its service behaviour. The present study is a part of an extensive research project, CONSTIN, between Oslo Metropolitan University and Niccolò Cusano University aiming to evaluate the steel-to-concrete interaction in the presence of corrosion and to establish a variation law for the bond strength as a function of the corrosion level. The research aims to assess the influence of different level of corrosion on the interface between the concrete and the most typical steel reinforcement typologies (the steel strands, and the smooth and the ribbed bars), characterized by the same diameter (equivalent to 12 mm) and bonded length. The different level of corrosion is reached with a specific duration of exposition of the embedded reinforcements to the accelerated electrolytic corrosion process. Some details about the laboratory procedure, the duration of exposition and the current density will be provided. The preliminary results of the experimental campaign will be presented.