EXPERIENCES WITH THE USE OF CUPOLA FURNACE SLAG IN CONSTRUCTION INDUSTRY

Abstract

Gray cast iron is still the most used material for the production of castings. It can be made in several ways, but the most efficient and economical way to make gray cast iron is in a cupola furnace. A by-product in its production is slag, which arises from impurities that may be present in the charge, from coke, which is used as fuel for the cupola furnace and part of it also passes into the slag, from the lining of the cupola furnace as well as from oxides formed during of the smelting process, sulfides and phosphides. The amount of slag from the cupola furnace represents 5-10% of the weight of the produced metal. Gray cast iron can be melted in a hot-air or cold-air cupola furnace, and the slag can be cooled on the air to form lump slag, or it can be water-cooled to form granular slag. In the article, the authors dealt with the treatment of slag and its use in the preparation of concrete. In the first series of experiments, slag was used as a substitute for sand in concrete, being added in different amounts and the properties of the concrete were tested after 28 days, 3 months, 6 months and after a year. In the second series of experiments, it was ground to the grain size of cement and was added as a substitute for cement in concrete. The quality of the raw concrete was monitored by the cone test and the quality of the hardened concrete by measuring the compressive strength and hardness. However, the achieved results did not meet our expectations and were the worst compared to other metallurgical slags.