In reinforced concrete, when slits take places, the problem arises to control the growth of it. If the critical limit is exceeded due to further load increases, the final strength relies on the integrity of the tight rods. The ability of finding possible defects in these rods and in controlling the relevant growth is therefore of great importance in structural safety at the ultimate stage. In particular, thin reinforced concrete structures draw researchers attention to such a point that several theoretical models have been developed with the aim to reproduce with adequate reliability the real behaviour, taking into consideration the actual deformability, the rising and spreading of fissuring, together with the mechanisms and the loads leading to collapsing. In this work, an experimentation is carried out on a deflect less reinforced concrete specimen, which underwent to rising traction up to the fissuring. The employed investigation technique is an application of the well-known eddy current-based methodology. The magnetic fields maps which were got by this way constitute an electromagnetic representation of the tensional condition of the specimen at the different values of the applied traction, using the above mentioned experimental database, concerns the extraction of inferences to predict and assess the growth of defects in reinforced concrete elements similar to the employed specimen.