Rebar's corrosion is a serious problematic of civil constructions that hugely reduces the serviceability of structure, mainly in maritime zone due to aggressive agents that could lead to corrosion. For decades, many Non-Destructive (ND) methods have been developed to address this issue, however, most of them focus on diagnosis the rebar’s corrosion and there is a lack of reliable techniques for prognosis. Under framework of French ANR project LabCom OHMIGOD, we want to propose a novel Structural Health Monitoring (SHM) embedded tool for detection of chlorides penetration front in cover concrete, as preventive ND method. It calls Functional Magnetic Material (FMM) by using magnetic and ferromagnetic materials. The output signature is magnetic flux density (B), as Magnetic Observable (MO). Embedding FMM tool in concrete, exposes to chlorides penetration, it would be corroded. By evolution of corrosion, its geometrical and physical properties would be changed and it causes the MO variations. Using an external interrogator and regular monitoring, we aim to evaluate the probability of chloride ions in media, associated with MO variations caused by corrosion. To evaluate the tool’s performance, we would investigate the amount of MO variations by numerical modeling of corrosion on FMM tool and experimental test. Firstly, through parametric study on geometrical variation and also evolution of corrosion products layer on the tool, as index of corrosion, the amount of MO variations is investigated. Secondly, through a real time monitoring test of FMM tool, placed on concrete core and corroded by accelerating corrosion for 46 hours, the MO variations are also measured. Comparing the numerical modeling and experimental results demonstrate an upward MO tendency, in line with corrosion. Moreover, a similar relative MO variation range is obtained (about 14.01\% and 12.05\%, respectively, for experimental and numerical modeling) that validates the FMM tools performance as novel SHM technique.