The possibility of recycling the ash and slag mixture of the Mogocha boiler station (Trans-Baikal Railway) as part of a composite material for the device of protective layers under the ballast of the railway track and establishes the role of cryogenic treatment in the formation of its structure is established. A set of modern physical and physicochemical research methods were used to study the composition, properties, microstructural features of the ash and slag mixture to assess the efficiency of its use as a discrete phase and participation in the pro-cesses of composite structure formation.