The invention relates to a system for assessing chloride concentration at one predetermined area of a porous or composite material, such as a reinforced concrete structure, comprising a sensor (1) embedded in the predetermined area of the material, an analyser (2) connected to the sensor, and a processing module (4) connected to the analyser. The sensor (1) comprises two facing or coplanar electrodes (11), called electrodes, an intermediate layer (13) arranged between said electrodes, said intermediate layer being in contact with the material of the first area of the structure and comprising calcium aluminates. The analyser (2) is configured to apply an alternate current between the electrodes and output an impedance value or capacitance value of the intermediate layer. The processing module (4) is configured to compute a chloride concentration assessment in the predetermined area of the material based on the impedance value or capacitance value outputted by the analyser.