Corrosion study of steel rebars embedded in a 70-years-old concrete structure exposed to a sulphur-containing environment

摘要

Steel rebars embedded in concrete and exposed to mountain weather conditions in a sulphur-containing environment during 70 years were characterized. The research has the objective of understanding the rusting of steel in concrete in a non conventional environment, and provide information concerning the nature of the corrosion products formed on the steel rebars in order to make accurate predictions of the time-to-cover cracking by means of analytical models. The identification of a clear and unique corrosion pattern has not been possible. Apart from the compounds usually found in this type of studies (goethite, lepidocrocite, akaganeite, magnetite, maghemite, hematite, etc.), iron sulfides were also found in the present work. The presence of these compounds is due to the particular environment to which the structure was exposed, and it has been reported previously only in the case of corrosion of steel in anoxic soils. The different corrosion compounds found have volume expansions that lie between 2.08 (magnetite) and 3.48 (akaganeite), being this information relevant when evaluating analytical models to predict the time to-cover cracking.