Сonstruction, repair and reconstruction of roads require high costs of mineral raw materials in the form of sand, gravel, mineral powder. However, its reserves on the territory of our country are distributed unevenly, which causes significant transportation costs for the delivery of mineral resources to construction sites. In addition, mineral resources are inevitably reduced over time, which requires extensive involvement in the construction of roads of non-traditional types of raw materials, as well as industrial waste.
The paper presents the results of studies of the properties of electric steel slag, the current output and stored in the dumps for several years. The main component of electric steel-smelting slags, both fresh and dumped, lying in dumps for about 20 years, is shannonite or γ-modification of calcium orthosilicate C2S. It has been established that the mineralogical composition of the Oskol Electrometallurgical Combine's slag is represented by hematite, wuistite, calcite, periclase, and also portlandite, formed during quenching of lime. Analysis of diffractograms of slags of different shelf life shows that in the initial periods of slag storage in the dumps there is a final quenching of lime and its carbonization with the formation of calcite. The results of the determination of the granulometric composition of the slag of different storage periods showed a decrease with time of the number of fine fractions and an increase in large fractions. It is established that when using electric steel-smelting slags in the construction and repair of highways, it is necessary to take into account changes in the physical and mechanical properties of materials. The processes that take place during the maintenance of slags in dumps determine the suitability of the use of slag mineral materials in road con-struction.