Threshold chloride concentration for stainless steels activation in concrete pore solutions

The threshold chloride concentration for stainless steels activation in concrete environments depends not only on chemical composition of the steel and on pH level of concrete pore solution but is also considerably affected by the superficial state of the steel. The presence of scales leads to significant decrease of corrosion resistance. This study evaluates the corrosion resistance of various stainless steels exposed to pore solutions of fresh concrete by means of electrochemical methods. All tested materials with bare surface, except for martensitic chromium steel FeCr12, proved to be completely resistant to fresh concrete pore solution containing chlorides. If the surface is scaled, the identically high resistance cannot be expected even for the most alloyed stainless steels.