A cupola furnace is the most frequently used furnace aggregate for cast iron production. A by-product of the production of cast iron in cupola furnaces is cupola slag. Its amount is 40-80kg per 1 tonne of the produced cast iron, and that is one of the reasons why this material is not as favoured as, for example, the blast-furnace slag. The purpose of this article is to provide the basic information on the formation of slag in a cupola furnace, and its chemical composition, structure and current potential applications. The greatest potential for the use of cupola slag is in the building industry; therefore, a section of the present article deals with the property that plays an important role particularly with regard to the use of slags in the building industry, i.e. the slag hydraulicity. The achieved results indicate that the hydraulicity of the cupola slag is incomparable with the hydraulicity of the blast-furnace slag; this may be associated with the problems that arise when the slag of this type is used in the building industry. The authors used the air-cooled as well as granulated slags from cupola furnaces in the production of concrete that was made from the slags alone. While the air-cooled slag may be used as a partial replacement for the blast-furnace slag in concrete mixtures, the use of granulated slag from cupola furnaces as a replacement for granulated blast-furnace slag in cement-free concrete has not proven to perform well.
