Corrosion behaviour of stainless steel in concrete exposed to carbonation

The study investigated the corrosion behaviour of stainless steel in concrete exposed to carbonation. Three types of steel, SUS304 (18% Cr), SUS410L (12% Cr) and ordinary carbon steel SD295A, were cast in several OPC-concrete scenarios. The following were observed: (1) Both stainless steels were unaffected by carbonation in concrete with proper cover even with high water/cement ratio (0.7w/c) and high temperature exposure (40oC). (2) Galvanic effect was observed and enhanced by carbonation though was not a great corrosion threat for steels; while early ingress of carbonation (due to thin cover) served as corrosion threat for the economical SUS410L stainless steel; while both stainless steels remained passive at pH 8 solution. Overall, carbonation was not a great threat for stainless steels; however, some factors enhanced its effects. The new economical stainless steels (ex. SUS410L) with lowered chromium content merit caution when used in carbonated environments, especially in thin cover scenarios