Introduction. Currently, such an innovative material as composite cement mats (concrete cloth) is widely used in construction. Due to the novelty of this material, there are currently no approved regulatory and technical documents regulating the general technical conditions of the concrete cloth (including a list and normalized values of indicators that determine the quality of the material), as well as test methods for its normalized indicators.

The aim of the research was to study and systematize the currently available information about cement composite mats, as well as to form approaches for the development of a number of relevant regulatory and technical documents.

Materials and methods. A review, systematization and analysis of domestic and foreign research and practical works, as well as aspects of technical regulation for cement composite mats, has been carried out.

Results. The characteristic of the current status of technical regulation for cement composite mats is given, approaches for its development are indicated. The areas of application of cement composite mats are summarized; material quality indicators recommended for rationing and test methods for their determination; recommendations for the development of standard test methods are given.

Conclusions. To improve cement mats quality and accessibility, as well as to increase the share of their use in the construction industry, it is necessary to develop regulatory documents that establish technical requirements for the material, its standardized quality indicators and test methods for their control. When developing them, it is rational to use the accumulated experience of practical application and research of cement composite mats, which is summarized in this article and reflects the main trends in the development of the regulatory framework for this material.

Introduction. Blocks of non-combustible polystyrene concrete of D300 density grade, B1 compressive strength class with normalized thermal conductivity λ₀ = 0,078 W/(m·°C) and frost resistance grade not lower than F75, developed by LLC “Institute VNIIZhelezobeton”, were used in masonry with a thickness of 375 mm without special fireproof lining. Such masonry successfully passed standard fire tests for fire hazard and fire resistance, which showed the possibility of its use in external non-bearing energysaving walls of multi-storey buildings (up to 25 floors inclusive, about 75 m high).

Aim. Evaluation of the strength and deformation characteristics of non-combustible wall masonry made of noncombustible polystyrene concrete blocks with a density of D300 at design wind loads at a height of about 75 m. Materials and methods. Fragments of uncoated wall masonry 375 mm thick, 2,7 m high and 1,2 m wide of noncombustible polystyrene concrete blocks mounted on a mortar with over-all dimensions of 295 × 375 × 595 mm were tested.

The test procedure is in accordance with State Standard 8829-2018.

Results. The destructive bending load exceeded the calculated one by an average of 4,1 times, while the deflection in the middle of the fragment was 1,9 times less than the permissible one.

A methodology has been developed for calculating the strength and deformability of masonry of polystyrene concrete blocks under wind loads, taking into account the influence of horizontal and vertical masonry joints, which is scheduled to be reflected in Amendment No. 1 SP 434.1325800.2018.

Conclusions. The results of wind load tests showed that for unlined masonry made of non-combustible polystyrene concrete blocks with a density of D300 and a thickness of 375 mm, the requirements for strength and deformability are met with a significant margin. 
The results of tests for wind and fire effects of the specified block masonry make it possible to use it in nonbearing external walls of multi-storey residential energyefficient buildings up to 75 m high in virtually all regions of Russia.

Introduction. The article presents the methodology and results of design calculations and features of the technology of the construction of domes.

Aim. Development of design solutions for two main central (upper and lower) and four small domes of the Church of the Ascension of the Lord under construction in the city of Elektrostal, Moscow region.

Materials and methods. The project provided for the execution of domes in monolithic reinforced concrete using the technology of shotcrete in the design position. According to the project, the complete assembly of the reinforcement frames was carried out on the assembly moulds near the building. The finished frameworks were installed in the design position by a crane and were covered with a steel fine mesh. Concreting of domes was carried out by layer-by-layer application of fine-grained concrete by the method of shotcrete.

Results. A complex of works was carried out on the design and construction of two main central (upper and lower) and four small domes of the Church of the Ascension of the Lord under construction in the city of Elektrostal, Moscow region.

Conclusion. The experience of performing a complex of works on the design and construction of dome structures using shotcrete technology has shown the rationality of the design and technological solutions adopted and can be effectively used in the construction of objects with dome coverings made of monolithic reinforced concrete.

Introduction. The construction technology of prefabricated buildings, along with the high quality of construction, is widely used for all types of buildings and structures.

Aim. To maximize the safety of people and equipment after impact. This is achieved by:

1) development of a design solution for a thin-walled plate-membrane capable of obtaining significant deflections without collapse;

2) technologies for assembling spatial block modules made of membrane plates without welding;

3) working out technological issues of manufacturing plates-membranes; assembly of block modules; sealing joints between block modules.

Materials and methods. In the manufacture of membrane plates, fine-grained concrete of the VSM B25 P2 F200 W4 brand was used with the use of a fine additive (barite), spiral reinforcement of spring wire d = 1.6 mm.

Results. The proposed design solution has significant reserves of strength and deformability. This ensures the safety of people and equipment.

Conclusions. The use of spiral reinforcement makes it possible to manufacture thin-walled structures with the further construction of block modules with them and, after filling with light concrete, to obtain prefabricated buildings and structures that can withstand significant loads by external shock forces.

Introduction. The main results of the application of the method of acoustic emission criteria for the diagnosis of the pre-destructive state of reinforced concrete structures are presented. The paper considers the relationship between the origin and growth of microcracks in reinforced concrete beams with deviations of invariant ratios from stable values of acoustic emission parameters.

The aim of the research is evaluate the possibility of using the invariant method for the diagnosis of reinforced concrete structures. Refinement of numerical values of time and amplitude invariants, time and amplitude information parameters for reinforced concrete beams. Determination of the relationship of invariants with the scale of destruction in reinforced concrete structures.

Materials and methods. Experimental studies were carried out on reinforced concrete beams made of heavy concrete (compressive strength class B60, B90) and fiber concrete (compressive strength class B30, B60). In the process of testing the beams, acoustic emission measurements were carried out, the crack sizes were fixed.

Results. The test results allowed us to establish numerical values of time and amplitude invariant criteria, time and amplitude information parameters for reinforced concrete beams. The numerical values of the time invariant have values close to 1, the amplitude invariant has a value of 0,1, and the information parameter of the time intervals and the amplitude information parameter are equal to 0 at the initial stage of loading the samples.

Conclusions. Studies have shown the possibility of quantifying the size of cracks (the total length in the control zone) of the structure using the invariant method. The most informative are the time and amplitude invariant criteria.