Why is steel slag the proven industrial aggregate? There are two principal reasons. Firstly, there is a long success record in many countries, and secondly the material is environmentally friendly and will always be available wherever steel is made. It is only since the early 1900's that slag has been extensively re-cycled in a global sense. Some of slag's common uses today include concrete and asphalt aggregates, road sub-base, pipe bedding and railway ballast. The first documented use of blast furnace slag in asphalt was in England in 1903 by E. Purnell Hooley, the Nottingham County Surveyor. Today, almost all blast furnace slag in industrialised countries is used for aggregates and cement production. Steel slag, as distinct from blast furnace slag, is generally considered unsuitable for use in concrete because it normally contains small quantities of expansive lime and Magnesite. However steel slag has been commercially used as a road aggregate for over 90 years, and as an asphalt aggregate since at least 1937. In other fully industrialised countries like USA, Canada, Australia, New Zealand, Singapore, Japan, Europe and in some South America countries, slags are no longer viewed as wastes, but as "process co-products". All Ferrous slags contain varying amounts of valuable metal which can be recovered by a magnetic separation methods, and at the same time valuable construction aggregates are made by crushing and screening. Converting a disposal cost into a sale revenue offers considerable cost benefits to the steel-maker whilst giving engineers access to quality raw materials and at the same time reducing the consumption of mineral resources. This paper focuses on steel slag, its value as a cost-effective high performance construction material, and the potential benefits for steelmakers, slag processors, engineers and the community at large. (A)
Abstract