The problem of the beneficial use of large-tonnage industrial waste is acute all over the world. The metallurgical industry is no exception. One of the actual areas of application of such slags is the construction industry. Often, slags have many impurities that adversely affect the quality of the materials from which they can be made. However, in a small amount they can be used as pigment dyes, which make it possible to obtain materials of an unusual color. Decorative concretes differ from ordinary "gray" concretes in that they give architectural expressiveness to products, primarily for finishing works (walls, floors). The selection of the composition of such concrete requires a thorough study of both the raw materials themselves, including slags, and the selected compositions based on them. The article presents studies of finely ground slag from gas cleaning of metallurgical production, including physical and chemical methods. The analysis of the influence of the multicomponent composition of metallurgical slag on the structure and properties of the future composition of concrete is given. It was revealed that almost all components of the slag do not have a positive effect on the hydraulic or pozzolanic activity of the binder during the formation of the structure of the cement stone. More than half of the constituent minerals of the slag contains iron-containing compounds, giving the slag a rich brown color. The slag has a slight plasticizing effect. The slag particles contribute to the release of water retained by the cement particles, and, hence, to an increase in the total specific surface area of the cement particles. This structure hydrates the cement gel faster, resulting in faster hydration and strength development. Therefore, it is advisable to use the studied slag as a finely ground pigment additive in the selection of binder and concrete compositions. The finely ground structure of the slag makes it possible to improve the capillary-porous structure of concrete, reduce the consumption of cement by 5-15 %, while obtaining concrete in terms of compressive strength of a class of at least B30. The compositions of the decorative binder were selected using slag and fine-grained decorative concrete based on it for decorative flooring. The best concrete composition has strength class B40 for rooms with high impact intensity.