Evaluating the corrosion rate of low alloyed steel in Callovo-Oxfordian clay: towards a complementary EIS, gravimetric and structural study

Dedicated integrated experiments have been used to determine in situ the corrosion rate of low alloyed steels in geological repository mockups (90°C, anaerobic, 40 bars, slow synthetic water flux…). Two possible situations have been investigated: the steel can either be in direct contact with the host rock or in a solution rich in clay suspension. Electrochemical Impedance Spectroscopy (EIS), sampling gravimetry and microanalyses have been performed to determine the corrosion rate evolution with the exposure duration of the specimens. Kinetic regime modifications have been linked to structural modifications of the corrosion products interface.