The article considers the relevance of the use of nanomodified concrete in construction. The compositions of the studied mixtures are given, as well as the methods of their preparation using ultrasonic dispersion, the results of the experiment on the destructive effect of standard samples of beams are obtained. The conclusions of the obtained experimental data are presented.

Keywords: concrete, foam concrete, carbon nanotubes, superplasticizer, dispersion

The main objects in the field of inspection and strengthening of reinforced concrete structures are the bearing elements of buildings and structures, however, a huge number of structures subject to the destructive effects of negative factors are reinforced concrete power transmission line poles and lighting poles. Due to the large margin of safety, often their damage is not critical and repair and restoration work is not carried out until the final loss of the bearing capacity of the structures. This state of affairs is a consequence of the significant labor intensity and cost of strengthening work, especially for power transmission towers located far from cities. Modern reinforcement methods based on the use of composite materials allow solving this problem without significant labor costs. These methods do not require laborious and time-consuming costs, which will allow you to quickly respond to the devastating consequences of negative factors that destroy power transmission line supports and lighting poles. This article discusses the existing methods for strengthening reinforced concrete supports of power transmission lines, identifies their shortcomings and proposes new methods based on the use of composite materials.

Keywords: concrete, reinforced concrete, reinforcement, carbon fiber, composite material, rebar, carbon fabric, supports

A study was made of aggregates used for the production of decorative concretes. Since slabs of these concretes are planned to be used for floors and platforms that are subject to high mechanical stress, aggregates must have the necessary properties. The resistance of crushed stone to impact on a copra, abrasion in a shelf drum and frost resistance were studied. For sands used as aggregates, such characteristics as granulometric composition, particle size modulus, stability of the stabilized mixture, etc. were determined. According to the results obtained, aggregate samples were determined that are most suitable for the production of decorative concrete, which are used for the installation of decorative floors and platforms.

Keywords: wear-resistant materials, decorative effect, size modulus, crushed sand, crushed stone

The article presents the results of computational studies that are part of the authors' comprehensive research on the development of a methodology for predicting the resistance of steel fiber concrete to thermal effects at NPP facilities with various parameters of dispersed reinforcement. The studies were carried out using selected models to describe the processes of thermal deformations and changes in the most important properties of steel fiber based on previously obtained experimental and calculated data on thermal changes of steel fiber on an optimized cement-sand matrix with five types of steel fiber with a volume content of 0.5% to 6% after heating at 110-1100 oC. Based on calculations in accordance with the accepted hypothesis and the selected models, the dependences of thermal changes in the properties of steel fiber concrete relative to matrix changes from the calculated changes in linear dimensions due to the formation of cracks in the fiber concrete are established. The dependences of thermal changes in the linear dimensions of steel fiber concrete due to the formation of cracks on the ratio of the calculated unreliaxed tensile structural stresses in the matrix to the tensile strength of the matrix are established. Based on the performed studies, a method for predicting thermal deformations, changes in mass, linear dimensions due to the formation of cracks, strength, water resistance of steel fiber concrete, based on thermal deformations and changes in the properties of the matrix, parameters of dispersed reinforcement is formulated.

Keywords: steel fiber concrete, prediction of resistance to thermal effects, cracking, thermal changes in linear dimensions and properties

The article collects and structures information about the effect of chemical additives on the properties of concrete and concrete mix. The relevance of topic is due to the fragmentation of the background information and the lack of data on the study of new additives. The presentation of information in the form of a morphological table simplifies the selection of additives and reduces the risk of errors in the selection of concrete composition. Mineral additives were not considered in this article.

Keywords: construction materials, concrete, concrete mix, chemical additives, concrete properties, concrete composition, modified concrete

The article is devoted to the selection of the mobility of the concrete mixture for monolithic densely reinforced reinforced concrete columns directly on the construction site. The main defects in pouring concrete mixtures are described, the causes of their occurrence are analyzed. Empirically, the mobility of the concrete mixture, the technology of laying and the organization of work during the concreting of structures of heavily reinforced columns were selected. Recommendations are given for eliminating defects in monolithic reinforced concrete columns.

Keywords: column, densely reinforced structure, monolithic structure, concrete mix, cone slump, plasticity of concrete, workability, composition selection, monolithic defects

The problems of modern monolithic construction, namely errors in the installation of sound insulation in monolithic construction, require special attention, since the increased level of noise and vibrations during the operation of premises affects the psychophysical state of a person. Modern enclosing structures are often used in standard solutions without the necessary additional sound insulation. Therefore, in order to develop and introduce effective measures to prevent existing defects in the premises, this paper lists the main factors affecting the high level of permissible noise in the premises. The practice of applied methods and solutions used to improve the sound insulation of individual structures is given. The technology of performing works on the device of sound and noise insulation in residential premises, with an indication of the maximum permissible noise level, is considered.

Keywords: sound insulation, shock noise, residential buildings, noise insulation, air noise, monolithic house, comfortable environment, noise, construction, materials

From the standpoint of controlling the behavior of steel floor beams during the operation of a structure, the use of elastically compliant joints in the beam support nodes at the construction stage is considered. Elastic joints are an intermediate link between an ideal hinge and an absolutely rigid connection of the beam ends to the main load-bearing structures and can provide an effective structural solution for connecting elements of any materials with a real reduction in their stress-strain state. The use of resilient joints can be an effective solution for running roofs and ceilings, in load-bearing structures of steel frames, multi-span beam structures. This approach, in principle, is also applicable to beam structures of a through section.

Keywords: system behavior control, steel structure nodes, elastic joints, joint stiffness, analytical solution, finite element method, high-strength fiber

The recycling of industrial waste has always been relevant. In the modern world with the development of technology and the construction industry, it is necessary to find new opportunities for the disposal of industrial waste. One of the disposal options is to obtain synthetic anhydrite. Features of production and the finished product of processing make it difficult to use a binder for housing and civil construction. The study of the process of hardening of anhydrite binder and the properties of the resulting stone allows it to be used in different technologies for the manufacture of various building structures based on this binder.

Keywords: gypsum, anhydrite, synthetic anhydrite, industrial waste.

This paper studies the effect of recycled fillers on the properties of waterproofing mastics made for the tough climatic conditions in Siberia. Currently mineral powders from carbonate rocks are used for mastics production. However, these rocks are not located in all regions of Russia Federation and the production of mineral filler powders from these rocks is often associated with great production costs. The aim of this study is to develop bitumen mastics with reduced overall production costs that are able to comply with GOST standards. The experiment was conducted to provide insight on the recycled fillers (RF) in reliability, durability, climatic, freezing resistance of bitumen mastics. The method we applied involved in classic (with limestone filler) bituminous mastics comparison with recycled mineral fillers the tailings of neutralization (Norilsk) as well as the waste of barite production (Chernogorsk). A laboratory test method for bituminous mastics was used so what we could ascertain their properties like softening temperature, penetration value, low-temperature extensibility, Fraas breaking point, Modulus of elasticity. Results indicate that the mastics freezing resistance have increased with combined use of the recycled mineral fillers and thermoelastoplastic elastomer (TPE) DST-30. They recognize the possibility of waste utilization as alternative fillers in bitumen mastics that could lead to cost reduction effect. Developed mastic compositions recommended for use in commercial construction which contribute to the goals of waste processing and recycling in the Krasnoyarsk Territory.

Keywords: stone-mastic asphalt concrete, industrial waste, nepheline sludge, mineral powder, stabilizing additive, cord fiber waste, bitumen, road surfaces

This publication is devoted to the method of applying coatings from various materials to carbide cutting tools by the method of electrospark alloying, as well as the experience of using this method in practice. The formation of the surface layer, its structure were studied, and cutting tests were carried out. It has been found that nickel and aluminum coatings are more resistant than copper and zinc coatings.

Keywords: coating, carbide, cutting tool, wear, electrospark alloying, roughness, hardness

The aim of the work is to study the possibility of using mineralized fiber as a damping additive in the production of paving slabs and curbs. Fiber mineralization was carried out with an electrolyte solution and sodium silicate. An assessment was made of the physical properties of fiber and their influence on the physical and mechanical properties of fine-grained concrete, hardening both under normal conditions and after heat and moisture treatment. It was revealed that the strength of concretes modified with fiber and hardening under normal conditions is higher than concretes that have undergone heat and moisture treatment by 4.2%.

Keywords: fiber, organic compounds, sugars, cement clinker, blocking, hardening, hydration, strength, paving slabs

The paper considers a structural model of a solid body. Yu. N. Malashkin proposed a structural model of concrete, the main idea of ​​which is an elementary volume in the form of a polyhedron formed from rod octahedra. When developing the model, only its analytical analysis was carried out. In this work, in the development of the model, its finite element analysis was carried out in the LIRA-SAPR software package. The study showed the coincidence of the qualitative and quantitative parameters of the model obtained by numerical and analytical calculations, confirmed its adequacy in relation to concrete.

Keywords: structural model, concrete, elementary volume, polyhedron, rod octahedron, finite element analysis, lira-sapr software package

The use of biogas complexes has found wide application, first of all, as a solution to environmental problems associated with the disposal of waste from the agro-industrial complex, as well as obtaining additional types of energy and organic fertilizers. Many designs of biogas plants have been developed that are suitable for operation in various climatic conditions. The choice of a biogas plant design is the most important stage of the planning process. The article discusses the improvement of the bioreactor installation in order to obtain a larger volume of final raw materials, increasing its quality and efficiency of the installation as a whole. The conditions that contribute to improving the efficiency of biogas plants are determined. The technical characteristics of the biogas plant are presented. The pros and cons of bio-installations, their impact on the environment are considered. The prospects for the development of this energy sector in Russia are assessed.

Keywords: biomass, biogas plant, gas production process, waste disposal, harmful emissions

Every year, for the implementation of any oil and gas project in the Far North, the largest oil and gas companies use new technologies. This is due to attempts to reduce the cost of field development and operation. The article reveals the advantages of using composite materials in the construction of oil and gas fields. The cost of using composite and metal supports is given. The main objects, the construction of which is possible with the use of composites, are shown, and conclusions are drawn on the large-scale introduction of this material during construction.

Keywords: composite materials, field development, construction, labor intensity reduction, construction time reduction

The increased fire hazard of foamed polymers hinders their widespread use in the construction industry. An effective method of reducing the combustibility of carbonizing polymers is the use of phosphorus-containing flame retardants. Therefore, investigation of the influence of phosphorus-containing flame retardants to the composition of pyrolysis products and operational properties – heat resistance, flammability, combustibility and smoke generating ability – is the important objective. In the article we have presented the results of related experimental studies. The effects of phosphorus-containing flame retardants on heat resistance and main operational properties related to fire-safety of foamed constructional polymers are examined. A correlation was found between the results of evaluating the combustibility of foams by the limiting oxygen index and the combustibility index. Optimal concentrations of phosphorus in the foamed thermosetting polymers are established. It was shown that optimal concentration of the flame retardants leads to low combustibility of polyurethane-, resole- and urea-based foamed polymers.

Keywords: foamed polymers, fire hazard, оптимальное сдержаниеreducing the combustibility, phosphorus-containing flame retardants, heat resistance, flammability, combustibility and smoke generating ability

In this work, the effective thermal conductivity of porous materials is studied by a numerical method. A technique for designing an insulating material with specified geometric characteristics is proposed, which makes it possible to predict the thermal conductivity of porous insulation with sufficient accuracy. The design of foamed porous heat-insulating materials was based on the 3D Voronoi tessellation. The effective thermal conductivity of porous media was determined for twenty structures with different geometric characteristics. The thermophysical properties of the material corresponded to melamine. To verify the numerical solution, the effective thermal conductivity of the melamine sponge was determined experimentally. One regular structure and three irregular structures were compared with each other. The porosity of the insulating structures ranged from 0.722 to 0.987, the fiber diameter ranged from 0.0489 mm to 0.1259 mm. A theoretical solution is proposed for determining the effective thermal conductivity of regular structures. The technique proposed in the work can be used to design heat-insulating materials based on additive technologies, with specified heat-insulating and structural properties.

Keywords: effective thermal conductivity, porous structure, porous insulating material, 3D Voronoi tessellation

The priority of modern construction is the consolidation of existing urban development, with existing infrastructure, communications, developed transport network, proximity to the historical center of the city, providing the population with comfortable accommodation and amenities. Construction has a number of features associated with the cramped conditions of the construction site, the development of underground space, which requires fundamentally new organizational and technological approaches in construction, justification and development of the most effective and economical methods for the construction of buildings and structures in dense urban development.

Keywords: cramped construction conditions, underground space, resource conservation, energy efficiency of construction facilities, construction production

The paper presents the results of engineering and environmental surveys at the object of accumulated environmental damage - an unauthorized dump on the territory of the Shuvalov industrial zone in the Leninsky district of Nizhny Novgorod. A description of the study of the territorial and natural features of the object is given: landscape, representatives of flora and fauna, as well as data from laboratory studies of soil samples. An analysis of the morphological composition of the waste and data on the volume and mass of the disposed waste are presented. The level of microbiological, parasitological, and chemical contamination of soil samples with heavy metals is assessed. For carrying out reclamation work at the site, the authors of the work propose a composition that includes natural mineral-organic compounds. The results of the laboratory application of natural mineral-organic compounds with the production of soil-recultivator from the screening of landfill masses are presented.

Keywords: industrial and consumer waste, engineering and environmental surveys, unauthorized dumping, soil pollution, heavy metals, technogenic soil reclamation, reclamation soil

The article is devoted to the problems of the use of building waste in the demolition of houses, as well as substandard products at housing enterprises. The issues of concrete scrap processing, methods of its crushing to obtain materials that can be reused to create reinforced concrete products and structures are considered. Concrete scrap has been investigated for compliance with requirements for large aggregate for construction works. Compositions based on conventional coarse aggregate, concrete scrap and conventional fine aggregate have been developed. For the compositions, the technological characteristics of the concrete mixture are determined, as well as the physical and mechanical characteristics of the concrete at 28 days of age. The use of such compositions for the production of reinforced concrete structures is justified.

Keywords: concrete scrap, secondary crushed stone, concrete, characteristics of concrete scrap, recycling, construction waste, large aggregate from concrete scrap, application of concrete scrap

Hardening of concrete in the conditions of a construction site under constantly changing temperature and humidity conditions does not provide the desired performance properties of concrete and reinforced concrete structures. An assessment was made of the influence of the conditions of hardening of concrete samples at a water-cement ratio (W / C) of 0.45 and a hardening of 28 days. The hardening of concrete samples took place under conditions of a normal hardening chamber (air temperature T = 20 ± 50С, humidity W = 90 ± 2%), samples in water when completely immersed in a bath at water temperature T = 20 ± 30С and samples immersed in a plastic bag , hardening in the conditions of the air environment of the laboratory (T=20±50C). The samples gain the greatest strength when hardening completely immersed in water, and the smallest when hardening in an insulating polyethylene sheath.

Keywords: concrete scrap, fractionated crushed stone, water-cement ratio, hardening conditions, clinker hydration, strength development kinetics, moisture migration

The article presents the calculation of various variants of corrugated rollers with different characteristics of wall shelf thicknesses and comparison with the standard adopted I-beam used in construction. The main requirement when comparing options is the maximum deflection of the studied beams with a deflection in the reference beam based on the calculation in the Ansys software package, which calculates models using the finite element method.

Keywords: corrugator, finite element method, Ansys software package, comparison of variants, modeling, I-beam, beam

An analysis of the use of ceramic products in the total volume of use of wall materials is given. It is shown that with the plastic method of molding ceramic products, a change in the quality of raw materials can lead to the production of low-quality products (defective products). The basic technological properties of clay raw materials from the Taushinsky deposit in the Perm Territory, as well as its granulometric and mineral compositions, have been studied. It is shown that the adjustment of the composition of the ceramic mixture with a change in the characteristics of the feedstock should be carried out taking into account the features of mineral formation in an 8-component oxide system. A comparison of the physical and mechanical characteristics of two batches of bricks of the current and corrected compositions was made, which makes it possible, with some assumptions, to consider them identical.

Keywords: ceramics, brick, clay, deposit, optimization,batch mixture, firing, production, plastic molding method , strength

The main message of the scientific article is overview of types construction concrete structures at low temperatures. Two main methods of concreting at low temperatures are considered. The first method is using of antifreeze additives. Second method is application of electric heating of concrete with PNSV heating cable. In end of the article shows a technical and economic comparison of these method, is given a short calculation.

Keywords: concrete, reinforced concrete, concreting, low temperatures, hardening problems, concrete strength, antifreeze additives, electric heating of concrete

The use of anti-friction materials in moving units reduces the likelihood of component wear, increases reliability, service life of parts and mechanisms as a whole. The paper considered the effectiveness of molybdenum coating in the design of oil and gas fittings, namely, an axisymmetric check valve and a control valve. Tests for strength, thickness, microhardness of the coating in the rack and pinion mechanism of oil and gas fittings were carried out.

Keywords: molybdenum, plain bearing, rack and pinion mechanism for oil and gas fittings, coating parameters, tests