Using the physical and chemical analysis, the possibility to obtain a dense and crack-resistant Portland cement-based composite material filled with aluminosilicate and glass microspheres and a complex additive which purposefully enhances each of the mentioned properties have investigated. During the molding of a composite material, in which particles of a filler and a binder have the same size in microns, micro-reinforcing fibrous additives will not be effective because their particles are larger than filler’s particles. To specify the conditions for the formation of a micro-reinforcing layer of etryngite needles and for increasing the density of the cement matrix structure, relevant theoretical and experimental studies were carried out and a complex additive consisting of calcium nitrate and chloride, carboxymethylcellulose and plasticizer was proposed. Based on the physical and chemical analysis performed, it has been found that adding a complex additive facilitates the compacting of the cement matrix structure through the additional synthesis of crystalline hydrates: ettringite, calcium hydrochloroaluminate, calcium hydroxychloride, and calcium hydrosilicates of the felt-like structure, which improves physical and mechanical properties of a Portland-based composite material.

The article deals with the analysis of SPT® polyurethane materials and maintenance technologies based on them, and an analytical review of literature on the topic. Solidification with SPT® materials and technologies makes it possible to compact unstable foundation soils of structures and buildings. The solidification is implemened through a guided increase of polymeric material injected into a foundation. As a result, polymeric root-like reinforcing bodies are formed in the foundation, and the water is extruded out of the soil, thus considerably increasing the bearing capacity of the foundation. In order to assess the actual efficiency of the material the authors conducted the full-scale research into the general overhaul technology of the pipe culvert, the static and the dynamic tests on the models of solidified soil was conducted and compared with the results of the tests on the models of non-solidified soil. The authors investigated into the life ratio of SPT® material and the soil solidified with it. By comparing characteristics of SPT® materials and technologies with those of conventional materials, the basic analogies and differences were established. And the possibility to use them for construction, refurbishment and maintenance of rail facilities was determined.

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