Low-modulus inclusions in the form of entrained air or ash microspheres in the composition of fine-grained concrete practically do not affect the ratio of the ultimate strength in bending and compression during hardening of concrete under normal conditions. After 75 freezing-thawing cycles, the ratio of the flexural and compressive strengths of fine-grained concrete with ash microspheres did not change, and in concretes with involved air, the influence of factors such as the type and dosage of redispersible powder and the type of cement increased sharply. Low-modulus inclusions have practically no effect on the ratio between the initial elastic modulus and the compressive strength of fine-grained concrete during hardening under normal conditions. After 75 cycles of freezing and thawing in concrete with entrained air, the influence of such factors as the type and dosage of redispersible powder and the type of cement on the ratio of the initial elastic modulus to compressive strength increases sharply. The cyclic freezing-thawing does not affect on the ratio of module and strength in concretes with an ash microsphere. Regardless of the presence of low-modulus inclusions, there is no clear relationship between adhesion to a concrete base and flexural strength of fine-grained concrete. In concretes with entrained air, the increase in adhesion to the concrete base after 75 freezing-thawing cycles, depending on the type of cement and dosage of redispersible powder, was up to 82%, and for compositions with an ash microsphere, up to 62%. Regardless of the presence of low-modulus inclusions, after 75 freeze-thaw cycles, adhesion to the base corresponds to class C-1. With an increase in the dosage of redispersible powder from 0 to 3% in compositions with low-modulus inclusions, an increase in adhesion to the base was noted up to 62%.

Keywords: dry mortar mixes, redispersible polymer powders, low modulus inclusions, adhesion to the base, elastic modulus, tensile strength, freezing and thawing cycles

The article presents theoretical studies of the effect of various plasticizers on the mechanical properties of epoxy compositions. Based on this, the method of plasticization of the epoxy polymer ED-22 was chosen using the introduction of modified epoxy resin UP-563, which differs from the previously used modified compositions for repairing automotive vehicles in the field the simplicity of the availability of modifications in the field and as providing the widest range of changes in the properties of the epoxy composition for USAGE field. The scientific novelty lies in the justification for the creation of a new repair composition consisting of ED-22 epoxy-diane resin modified by UP-563 laproxil for the repair of hull and capacitive parts of automotive equipment in the field, which has increased vibration resistance. frost resistance and impact resistance.

Keywords: epoxy composition, epoxy resin, restoration, automotive engineering, body part, chemical modification, oligomer, polymer

In this paper, the previously obtained equation of motion in displacements is used to determine the frequencies and forms of free oscillations of the underground gas pipeline. The problem of solving this equation is reduced to finding the eigenvalues of the determinant, which are the squares of the natural frequencies of the cylindrical shell. Neglecting the secondary coefficients of the determinant and equating them to zero, the formula for the square of natural frequencies of an underground rectilinear thin-walled gas pipeline exposed to the action of internal working pressure and longitudinal force is obtained, taking into account the reaction of elastic resistance of the soil. Substituting the values for the wave numbers in the longitudinal and circumferential directions into the obtained formula, expressions for determining the frequencies according to the rod and shell theory are derived.Using these expressions, the dependence of the frequencies of free oscillations of the depth of the pipeline at fixed values of the pipe wall thickness, the coefficient of elastic resistance of the soil and the length parameter of the plot, for different values of internal pressure, the ratio of longitudinal compressive forces. When analyzing the results, it was found that with increasing depth of the pipeline, the frequency of free oscillations decreases, and at a certain depth, the frequency of free oscillations becomes equal to zero, this indicates a flattening of the cross section of the pipeline. Using the dynamic stability criterion, for which the frequency of free oscillations turns to zero, an expression is obtained that allows to determine the depth of the pipeline at which the stability loss of the second kind occurs.

Keywords: pipeline, frequency of free oscillations, depth of laying, coefficient of elastic resistance of soil, loss of stability

The article deals with the survey of transport and operational condition of the highway R224 " Samara-Orenburg in which it was found that the roadway surface is in poor condition due to the presence of transverse cracks, ruts and pits. In a survey of 5 existing culvert structures were identified unacceptable defects in the structure. Based on the foregoing, the specified section of road be repaired in accordance with GOST R 50597-2017 “roads and streets” . Currently, economical and mobile methods of inspection of road structures are of particular relevance. Conducting engineering surveys of the GPR system MIRA was determined the constructive layers of road clothes light. The decision on milling to a partial thickness of the pavement that runs recyclers WR 4200, with the subsequent device of asphaltgranulate type To

Keywords: pavement engineering, GPR applications, roads, surveys, MIRA GPR systempurposes of ensuring flexibility of production

The influence of changes in the geometry of a metallic cylindrical mesh shell without reinforcements, with puffs and with horizontal trusses on the specific weight index is investigated. The span and the angle of the circumscribed circle of the shell are taken as the given parameters. They determined changes in the radius of curvature, height, cell size, shell length and stiffness characteristics of the rods. To determine the required specific gravity parameter, the number of elements was distributed by standard sizes. The calculations were performed using the application software PC LIRA. The obtained data were analyzed, as a result of which the optimal distance between the supports was determined, which made it possible to find the minimum mass and establish acceptable geometric parameters of the structure. In addition, extreme values were determined, beyond which the study of the influence of changes in geometric parameters on the specific weight index becomes impractical.

Keywords: cylindrical mesh shell, element of reinforcement, geometrical parameter, specific weight index, element of tension, horizontal trusse

The article examines the influence of observance of the frame dome-shaped roofs assembly technology on the quality of the completed object. This theme is relevant enough, as the building roofs, constructed in accordance with the aforementioned technology, are often found in modern business clusters. It`s natural that prospective investors are interested in perfect quality and seamless service properties of similar construction object designs. The authors considered features of the frame dome-shaped designs construction and assigned its pros and cons; the review of the technical investigation of one of the shopping centers was conducted with purpose of showing the consequences of inaccurate observance of the specified designs installation technology. Subject to facility technical investigation results, recommendations for the safety operation of dome support structures were given.

Keywords: steel designs, frame dome-shaped objects, frame dome-shaped roofs installation, technical investigation of frame dome-shaped roofs, spherical sheath imperfections

This article discusses the calculations of the feasibility study for the expansion of housing construction in Rostov-on-don. The main part of Rostov-on - don, where the vast majority of buildings are concentrated - the city center, residential areas, main production areas, special purpose facilities-are located on the high right Bank of the don. Active formation of new multifunctional planning areas of the city: North, West, North-East. Leventsovsky and Suvorovsky districts are under construction. For implementation of design decisions on development of housing construction in Rostov-on-don there is a need of an economic assessment of possible options that it is necessary to study in pre-project documents, such as the feasibility study of construction of objects.

Keywords: "feasibility study, Economics of urban planning, pre-project preparation, investment efficiency, urban planning, construction Economics, effective design solutions, design, housing construction, housing stock. environmental requirements, construction indu

The paper presents the research results of the influence of materials, which change a phase on the exterior surface of the outer shell, on forming of the heat flow mean value for one year, calculated on change of the exterior temperature per every three hours. The correlation between heat flow and characteristics of the phase-change material was studied. Such materials increase heat lag of the outer shell and allow reducing the amount of electric energy required to keeping of indoor climate. The paper presents the research results of the influence of materials, which change a phase on the exterior surface of the outer shell, on forming of the heat flow mean value for one year, calculated on change of the exterior temperature per every three hours. The correlation between heat flow and characteristics of the phase-change material was studied. Such materials increase heat lag of the outer shell and allow reducing the amount of electric energy required to keeping of indoor climate. Based on the implementation of the method of math planning of experiments the sufficient math model of the dependence of the heat flow density on the material coating thickness, latent heat of transition, heating capacity value and thermal conductivity before and after phase change was made. The mathematical model coefficients were interpreted and best values of very factors based on desirability function were determined. Based on these data the selection of the material with phase-change temperature of about 0 0C for Krasnoyarsk was made.

Keywords: energy efficiency, heat flow, heat saving, heat-storing material, phase-change heat storing, phase-change material

One of the main sources of electromagnetic radiation in the environment are power lines, not taking into account this fact, there are increasingly cases of construction of buildings in close proximity to the boundaries of the security zones of air lines. The purpose of this study is to improve the electromagnetic safety of the population, as a result of the use in the construction of residential facilities located near overhead power lines, structural and finishing materials with the greatest shielding ability. On the example of "corrugated Board" of different brands, used as a shielding material, the indicators reflecting the efficiency of electromagnetic shielding are obtained. Also, according to the results of the study, it was found that not only the raw material from which the material is made plays a role in the shielding of the electric field, but also its form factor.

Keywords: electromagnetic radiation, electric field, security zone, shielding ability, voltage class, power line, material

The article identifies socio-economic factors affecting the industrial architecture of the southern Federal district. The analysis of the statistical data characterizing the existing enterprises is carried out. The features of processing and food industry of the southern Federal district are considered. The features of the architecture of the modern processing enterprise are formulated.

Keywords: industrial architecture, architecture of objects of the processing industry, economic factors, economy of the southern Federal district, energy efficiency, flexible planning solutions, functional mobility, blocking of premises

The paper focuses on energy efficient reconstruction of construction systems by means of their upward extension using modular spatial structures. It is further noted that the existing contradictory definition of the term “modular structures” necessitates classifying modular structural elements by spatial dimension, type and size, weight, degree of prefabrication, constructability and environmental safety. A list of the world’s leading manufacturers is provided featuring modular spatial structures to be used in the construction of new buildings and reconstruction of existing buildings. Also, the paper underlines the importance of using added stories in making modular roof structures of lightweight metallic structures (LMS) and lightweight thin-wall steel structures (LTSS) and provides an overview of the main types of modules, pointing out the key benefits of modular structures.

Keywords: modular building structures, energy efficient reconstruction, upward construction, structural and non-structural modules, constructability

Research was conducted in the urban agglomeration (Sredneahtubinsky district, Volgograd region) / experimental territory and SNT Oroshenets / control-conditionally clean zone for assessing environmental pollution with impurities of acidic and alkaline substances with a simultaneous assessment of their electrical conductivity. The object of the study is the leaves of apricot trees (Prúnus armeníaca), the subject of the study is aqueous dust suspensions (washing off the dust from the leaves of apricot trees (Prúnus armeníaca). The obtained results indicate acidic media of aqueous dust suspensions (pH = 4.6-5.5) s high electrical conductivity (47.1-80.72 μS / cm) in the experimental territory compared with the control-contaminated clean zone (pH = 6.3; EC = 38.1 μS / cm), which indicates the presence of dust particles heavy metals and / or acid oxides and / or hydrogen sulfide and others in of substances that got into them from atmospheric air. This indicates certain environmental risks to the environment and human health. In the future, it is necessary to identify the source of environmental pollution and the development of environmental measures to improve the quality of atmospheric air in the Central Akhtuba district of the Volgograd region.

Keywords: dust particles, monitoring, plant leaves, urban areas, residential areas, urban agglomeration, atmospheric air, electrical conductivity (EU), hydrogen index (pH), impurities, aqueous dust suspensions

Today in Russia there is an acute problem of processing of waste of the logging and wood processing industry. At almost all stages of timber production, waste is generated, which is disposed of or left to rot. Felling residues obtained in the process of cutting operations are used least of all. Currently, loggers leave up to 30 % of only the stem of trees, primarily low-quality wood, not to mention twigs, conifers, stumps, while logging waste is a valuable raw material that can and should be used for further processing. The article discusses the prospects for the development of the timber industry, including related to the rational use of wood resources. A number of experiments were carried out in order to determine the influence of design and technological parameters of knife equipment on the quality indicators of wood-fiber semi-finished product.

Keywords: insulation material, finishing material, grinding, wood fiber semi-finished product, cutting waste, integrated use of wood, grinding machine

An overview of the actual problems the question of environmental or "green" building in Russia and the CIS countries. The study identified several key issues. The range of ways to solve them proposed on the basis of existing systems of environmental certification (assessment) to develop a system of assessment of the CIS countries. The list of evaluation criteria given in this article is not exhaustive and may be amended by agreement of the CIS member States.

Keywords: green building, green building, green buildings, CIS States, evaluation criteria, certification, environmental efficiency, greening, environmental management, environmental safety, environmental protection

An experimental study of the power amplifier in the frequency range 0.1-1 GHz. The amplitude and amplitude-frequency characteristics of the amplifier are obtained. The dependence of the second harmonic level of the useful signal on the input power is removed. It is shown that in the operating frequency range the gain is not less than 25 dB, and the upper limit of the linearity of the amplitude characteristic of the output is not less than 1 mW

Keywords: Transistor amplifier, ultra-high frequencies, amplitude response, amplitude-frequency response, upper limit of linearity of amplitude response, second harmonic