Introduction. The use of the thermal power station’s (TPS) waste in the construction industry becomes the norm in world practice of recent decades. Basically, the researches use ash and slag in the construction of automobile roads as a material for filling the subgrade or in the form of a cement-bound material in industrial and civil construction as a material for planning work, when filling inconveniences and quarries. However, the potential of the ash and slag’s usage is much wider. Coarse-grained slag deposits that form in the zone of slag erosion have a greater potential for application than other ash and slag mixtures, however, these mixtures have been less studied by both domestic and foreign researchers. The paper discusses the use of the boiler slag formed at power plants with boilers involving liquid slag removal for the construction of road pavement bases with the position of its mechanical properties.Materials and methods. The author studied samples of boiler slag from Novosibirsk TPS-2, operating (Kuznetsk coal basin) and Novosibirsk TPS-3 (Kansko-Achinsk coal basin). Moreover, the author determined the crushing losses of individual fractions of the investigated materials in a dry and water-saturated state. The author determined the modulus of deformation of boiler slag.Results. The researcher found the difference in mechanical strength of the different genesis material. The crushing values of the investigated materials are determined.The author estimated the graphs obtained during testing and calculated the deformability characteristics of the material.Discussion and conclusions. The author determines possible directions of the studied materials’ usage in the road construction.The author has read and approved the final manuscript. Financial transparency: the author has no financial interest in the presented materials or methods. There is no conflict of interest.