On the Role of Iron Oxides in the Electrochemical Behaviour of Steel Embedded in Concrete

摘要

Magnetite is a common product of iron corrosion and oxidation processes. This mixed Fe~(2+)/Fe~(3+) oxide can transform reversibly into species having higher or lower oxidation degree than the stoichiometric 1:2 Fe~(2+) to Fe~(3+) ratio. The redox activity associated to magnetite transformations is of major importance in alkaline solutions as those found in concrete pores solution and can mask the electrochemical response corresponding to iron corrosion. The present paper discusses the state of the art on this aspect. It appears that the electrode potential (or the corrosion potential) is a key parameter necessary for assessing steel rebars corrosion rate as well as for defining the critical ratio Cl~- to OH~- necessary for rebar depassivation.