This paper reports the results of experimental research of the effect of strain-restriction conditions on the structure and properties of sulfoaluminate expanding cementitious materials. Theoretical analysis of the development of pattern formation processes is performed by applying the developed rheological model, illustrating features of the kinetics of structure-forming processes according to the ratio of the potential index of extension with linear, flat and volumetric limitation of deformations of the extension. The results show that rheological model adequately correlates with the results of experimental studies and can be described mathematically. Found that with the volume limitation of deformations arising when mixing crystallographic phases with high density and strength, the pore structure of the cement stone contains mainly gel pores. This is the main prerequisite for obtaining a dense, high-strength and durable structure of cement stone and concrete on its basis.

Introduction. The paper substantiates the actuality of the problem connected with obtaining efficient fine concretes possessing enhanced crack resistance, tightness, and duration for tunnel construction. This aim is pursued with the application of expansive cements (EC). Materials and methods. Various types of expansive agents were used in composition binders. Portland cement PTs 500 D0 was taken as the basic Portland cement. Studying hydration and structure formation processes during hardening of the ECs and EC-based concretes was executed utilizing a system of physicochemical methods. Assessment of construction and technical properties of the fine concretes based on composition binders was accomplished using standard research methods. Results. Analysis results are given for the effect of type and amount of the expansive agents on strength and volume deformation values of the concretes used in tunnel installation construction. Improvement of physical, mechanical, and technological properties and performance of sprayed concrete is shown. A general mechanism of influence of expansive additives (EA) on fine concrete properties is established. A classification of expansive cements for solving various tasks in tunnel installation construction is suggested. Conclusions. EA application efficiency is theoretically substantiated and experimentally proved for the case when the EA is used as an active agent in the composition binder for sprayed concrete in tunnel construction. General enhancement of technical indicators of concrete mixture and concretes is determined. EA classification is suggested for the different extent of hydrated EA expansion and various construction tasks. Replacement of standard Portland cement for an EC for underground structures concrete used in tunnel construction provides a significant increase in their maintainability.

The development of a modern city and the increase of its transport infrastructure, in particular metro facilities, has a significant impact on the urban environment and requires the development and implementation of a set of special protective measures. Moreover, if the construction of metro station complexes is carried out, as a rule, in relatively free areas with minimal impact on the surrounding buildings, then during the construction of tunnels and tunnel structures, engineering communications, buildings and structures located on the earth’s surface, including transport facilities, architectural monuments and cultural heritage objects fall into the zone of their influence. The effectiveness of design solutions for the protection of objects that are in the zone of influence of the construction of underground structures is largely determined by the degree of reliability of the assessment of geotechnical conditions and the results of the survey of the technical condition of building structures. Analysis of the causes of the formation and development of emergency situations and incidents arising in the construction and operation of underground structures shows that they are mainly the result of the use of unreliable initial engineering-geological and hydrogeological conditions, significantly changing due to intensive urban development. The resulting barrage effect, changes in groundwater levels and directions that are not taken into account at the design stage, can be accompanied by significant deterioration of soil properties and the General stress-strain state at the base of existing buildings and structures. This suggests the need for careful study of the properties of soils at significant depths, the development of forecasts of possible changes of the state of the soil massif and hydrogeological conditions, the implementation of a comprehensive survey of the bases of closely spaced buildings and structures, and significantly larger volume of engineering-geological surveys compared to the current regulations.

Introduction. The study proves actuality of the problem connected with obtaining efficient slag-alkali binders for usage in soil jet cement grouting. Replacement of usual portland cement for a slag-alkali binder in geotechnical underground construction activities allows solving a problem of waste (slag) utilization and increase economic efficiency of the soil jet cement grouting. In view of cement grouting technology features and possibility of usage cementation mixtures with various engineering characteristics for different soil types, a broad nomenclature of slag-alkali compositions can be used for obtaining soil-concrete structures. Materials and methods. Different types of slag were studied as constituents of composite binders. The PTs 500 D0 cement was taken as the basic portland cement. Standard requirements for cementation mixtures of mixing and pump facilities for soil-concrete bodies became the criteria. Investigations of hydration and structure formation during hardening of slag-alkali binders and soil-concretes on their base were conducted using a system of physical and chemical methods. Evaluation of construction and engineering properties of the composite slag-alkali binder was accomplished in accordance with the methods as per GOST 10181-2014 and GOST 5802-86 state standards. Results. Results of analysis how the slag type and amount influence the physical and mechanical properties of the binder used for jet soil cementation are presented. The article shows improvement of physical, mechanical, process and usage properties of the slag-alkali binder. General mechanism of impact of the slag on properties of the cementation mixture were revealed. Conclusions. Efficiency of application of the slag as an active component of the composite binder for jet cementation in geotechnical construction was theoretically substantiated and experimentally demonstrated. General applicability of the obtained concrete mixture based on the slag-alkali binder is stated for usage in cementation methods of improvement of technical parameters of concrete mixture and concretes. A classification of expanding cements possessing various expansion degrees was suggested for solving different construction problems.

For the execution of the works on the tunnel structures under water-saturated unstable soils of the nature plavannya, provided for their stabilization and strengthening with the use of chemical methods and technological equipment for 2-component jet grouting. An important factor determining the effectiveness of mineral-based injection systems is their material homogeneity with concrete enclosing structures of tunnel structures, high strength and durability, low filtration coefficient, manifestation of the effect of self-healing cracks in concrete with a width of up to 1 mm. The main criterion of manufacturability of injection mixtures designed to eliminate water seepage in the tunnel and peritonealny structures, is a low viscosity and a high sedimentation stability, stored for up to 90 min controlled structure and kinetics of curing after injecting works, durability, thermo frost, frost-salt resistance the.Based on these conditions, as well as taking into account the variety of tasks associated with the elimination of water in underground structures, experts, our UNIVERSITY developed and mastered the injection of a mixture of mineral-based «SFC+», «Aqualiner-U», «United Aqualiner-MD», «Intracom». It should be noted that particularly finely dispersed binders «Intracom» was developed in the framework of the program of import substitution, as an alternative mineral binder «microdur the» widely used for making various injection systems mineral Foundation.