Steel in concrete with blastfurnace slag aggregate

Abstract

Summary Tests have been carried out on the rate of weight loss of steel in aqueous extracts from four air-cooled, crystalline blastfurnace slags and on steel reinforcement in concrete prisms containing such slag as the coarse aggregate exposed for two years. The results indicate that, whereas theoretically the sulphide content of the aggregate may influence the corrosion behaviour, under practical conditions negligible corrosion occurs even at low (¾ in.) depths of cover. It is concluded that the alkalinity produced by reaction of the slag with water restricts the extent of corrosion and that blastfurnace slag may be used satisfactorily as coarse aggregate in reinforced concrete. The work described forms a part of a programme which included tests of slag concretes without metal reinforcement, for compressive and transverse strength, sulphate resistance and dimensional stability. The results of these other tests are reported in a separate paper in the same issue.