To create composite building materials with a polymer matrix, various fillers of both plant (wood-polymer composites - WPC) and mineral (mineral-polymer composites - MPC) origin can be used. The article evaluates the feasibility of using twelve different minerals in MPC from the standpoint of strength, cost and weight of the resulting materials in comparison with similar indicators of WPC. By sequentially considering each of the evaluated parameters, the sample of fillers is reduced by excluding combinations with characteristics worse than those of the reference material - a wood-polymer binary composite consisting of wood flour and polypropylene. It has been shown that one of the most effective mineral fillers can be waste from construction industry enterprises, as well as structures recycled during the demolition of buildings and structures.

Keywords: composite, matrix, filler, mineral, wood flour, dust, cost, volumetric weight, strength, elastic modulus, Poisson's ratio

The article is devoted to the topic of secondary use of oil industry waste, namely drilling mud, as an additive in the production of building bricks. In the article, the most used methods of drilling mud processing in the oil production industry are discussed. To date, there is no ecologically effective method of processing, utilization and neutralization of drilling waste. Processing technologies that involve the use of drilling waste as secondary raw materials are gaining popularity, but are not fully developed. Special attention in the article is devoted to consideration of the use of drilling mud waste as a secondary raw material. The laboratory studies of the application of drilling mud in the production of ceramic bricks are presented, the main purpose of which is to reduce the negative impact on the environment, reduce the costs of transportation, storage, processing of drilling waste, as well as the economy of natural resources.

Keywords: drilling, oil industry waste, drill cuttings, sludge pits, negative impact on the environment, recycling, secondary resource, component composition, construction

The analysis of the dependences of the "flexural strength – compressive strength" of ordinary concretes obtained as a result of processing numerous experimental data of the authors and borrowed from published works, as well as data presented in various regulatory documents is presented. Based on the obtained regression equations describing the dependence of the flexural strength of concrete on the compressive strength in the compressive strength range from 30 to 100 MPa, it is concluded that it is advisable to normalize the classes of flexural strength without taking into account the prescription features of concrete. Some inconsistency of the ratios of classes for flexural strength and compression in the analyzed regulatory documents has been revealed. The high reliability of the previously obtained dependence of the flexural strength of concrete on the compressive strength has been confirmed. A formula is proposed that takes into account the effect of the addition of silica fume in the composition of the concrete mixture on the ratio of flexural strength and compression. The role of the quality of aggregates in ensuring high flexural strength of concrete is noted.

Keywords: the flexural strength of concrete, the compressive strength of concrete, concrete strength classes, concrete for road and airfield coatings

The features of classification of construction products and construction materials are considered, and optimization of their existing classification structure is proposed. The analysis of existing domestic and international systems of classification of construction information, domestic normative and technical literature is carried out and classification features for construction material and construction product are determined. The optimization of the classification tables (CTs) based on the application of the principles of the ISO 81346 standard series and the refusal to duplicate the structure of the construction resources classifier, on reducing the number of classes and subclasses taking into account the ISO 81346 criteria and moving classes and subclasses within CTs with the corresponding changes in the code designations is suggested.

Keywords: construction information classifier, information modeling, information model of capital construction object, classification of construction materials and products

In this paper, the analysis of technical solutions in the manufacturing technology of concreted pipes is considered. When constructing underwater crossings, the most reliable and effective method of ballasting is the method involving the use of pipes with a solid concrete coating. Concrete coatings, among other things, provide protection of the main pipeline from mechanical damage, as well as from the effects of an aggressive environment. The compositions of fine-grained concrete for concreting the surface of steel pipes using non-recycled waste of steel wire rope or pipe production are proposed. It has been established that the use of these wastes in certain dosages contributes to an increase in the strength of concrete, high frost resistance while reducing the amount of expensive heavy aggregates.

Keywords: weighting pipe coatings, production waste, fine-grained concrete, strength, frost resistance

The article presents the technological aspects of obtaining solid synthetic hydrocarbons (paraffins) used to obtain and improve building materials. It is shown that a promising alternative to petroleum paraffins is the production of synthetic hydrocarbons from non-oil, including renewable carbon-containing raw materials. The main reaction conditions, synthesis catalysts, promoters that contribute to the maximum yield of a solid product, the prospects for the use of biomass, carbon-containing wastes, and carbon dioxide in the technology for producing synthetic hydrocarbons are considered.

Keywords: synthetic hydrocarbons, catalysts, promoters, building materials, modifiers

Products made of gypsum binders have heat and sound insulation properties, fire resistance, high technical, economic and environmental indicators, which are used in construction in the construction of internal walls and partitions, the total area of which, as a rule, is several times larger than the area of external walls. By reducing the density of gypsum products due to the introduction of light aggregates, it is possible to reduce the mass of walls, lighten the building, reduce the load on foundations and reduce the cost of construction, while improving thermal protection. However, traditional lightweight fillers increase the water demand of the mixture and reduce the strength of the material. Therefore, in the article, the purpose of the study was to determine the optimal composition of gypsum compositions with various types of filler to obtain the best set of properties of the obtained samples.

Keywords: gypsum concrete, perlite, vermiculite, experiment, filler, density

The article considers the use of collapsible road surfaces on temporary roads and develops a method for substantiating the composition of a set of collapsible road surfaces, the use of which will ensure the construction of a section of highway in the most likely conditions, such as entrances to construction sites, as wooden roads and even bridges, approaches to the bridge, detours of main roads during construction. the proposed method of substantiating the composition of a set of collapsible pavement allows you to calculate the composition of the set not only taking into account its weight and size characteristics, but also the conditions of use. The main of these conditions is the uncertainty of the length of the sections of the highway that require the use of the SRDP. In contrast to the existing ones, the proposed method allows to reduce the influence of uncertainty and obtain the composition of the kit, the use of which will ensure the construction of a section of the highway in the most likely conditions.

Keywords: highway, entrance, road surface, bridge, approach to the bridge, construction site, collapsible road surfaces, slab, road construction, method

The assumptions of mathematical models for calculating the crack resistance of reinforced concrete structures are considered. For each of them, an analysis was carried out to determine whether they correspond to reality throughout the entire life cycle of the structure: from the hardening of the concrete mix to destruction. Based on the results of the analysis, it was proposed to use only one single calculation at the level of standards to assess the crack resistance of structures - according to the crack opening width, acrc. So, for example, at a certain value of acrc, the structure will still remain airtight (the cracks will be non-through), and if this value is exceeded, it will not. At the same time, the calculations already available in the norms for limiting permeability and the safety of reinforcement will still remain in demand. At the junction of the theory of damage accumulation and nonlinear fracture mechanics, a compressed algorithm is proposed for possibly taking into account the influence of cracks at all scale levels of the concrete structure, the key for which is the normalization of the statistical parameters of the distribution of discontinuities by diameters, lengths, openings, depths, directions, distances between discontinuities, etc.

Keywords: reinforced concrete, crack resistance, cracking moment, crack width, plasticity coefficient, damageability, non-linear fracture mechanics

An approach is proposed to determine the parameters of concreting flat massive foundation slabs - the operational performance of the concrete mix supplier, vehicles and concrete pump, taking into account the limiting factors - the intensity of the supply and placement of the concrete mix and the time of overlapping layers. A scheme for determining the overall coefficient of operational performance is proposed. As a result of timing, the values ​​of the transition coefficient from technical to operational productivity, respectively, for a concrete mixer truck with a volume of 10 m3 from 0.54 to 0.65 and 0.41 for a concrete pump truck with a technical productivity of 120 m3 / h, respectively, were determined when concreting a massive flat foundation slab with a volume of 1500 m3 using concrete mix with grade P4 for workability at a delivery distance of up to 50 m. It is proposed to consider a coefficient that takes into account the decrease in the productivity of an autoconcrete pump due to the variability of the concrete mix supply mode as the main reserve for increasing operational productivity. Schemes are given for determining the duration of concreting a structure without technological interruptions, both with an equal thickness of the stacked layers, and with different schemes for assigning the thicknesses of the stacked layers. The inexpediency of erecting such structures with a layer overlapping time of less than 4 hours is shown. The approach considered in the work can be used to select rational methods for concreting such structures in a continuous pattern or with division into temperature-shrinkage blocks and the construction of working joints. The latter scheme, in connection with the problem of ensuring the quality of the seams and the solidity of the structure, seems to be less preferable.

Keywords: concreting intensity, technical productivity, operational productivity, massive flat foundation slabs, layer overlap time, layer thickness

The paper presents the results of research on the development of the composition of the raw mixture for the production of facing composite material for construction purposes. The composition of the raw material mixture included a brick fight as a filler, waste products from non-plasticized polyvinyl chloride as a binder and methylene chloride for dissolving polymer waste. This composition allows mixing and pressing without heating, which eliminates the possibility of destruction of the polymer component. After pressing, heat treatment is carried out at the solvent evaporation temperature. The paper shows the dependences of the main physical and mechanical characteristics of the resulting material on the degree of filling. The maximum amount of filler has been set, which allows to obtain the material without a lack of binder. With a lack of binder, a decrease in strength and an excess of the proportion of open pores over closed ones were observed. According to the results of the experiments, the polymer : solvent ratio and the degree of filling were selected, allowing to obtain a material with the maximum value of strength characteristics. Practical application of the developed composition of the raw mixture will allow complex utilization of low-demand and large-tonnage polymer and brick waste to obtain composite material for cladding buildings and structures.

Keywords: polymer composite material, facing material, polymer waste, brick fight, polyvinyl chloride, methylene chloride

The article deals with the problem of disposal of the sludge formed after the treatment of wastewater at the production of chemical fibers. Sludge after sedimentation is stored in storages and pollutes the environment. We carried out a comparative analysis of existing methods of disposal of sewage sludge from chemical production, which showed that the most environmentally friendly way is pyrolysis. We have analyzed the chemical and fractional composition of ash sludge after pyrolysis. The analysis revealed that the resulting ash waste is similar to ash from coal-fired power plants, which makes it possible to use it as a microfill for paving roads or sidewalks. By selling the ash waste it is possible to reduce the payback period of the pyrolysis unit installation and reduce the ecological load on the environment.

Keywords: pyrolysis, sludge, sediment, ash, disposal

The thickness of the steel sheets used in the element was gradually increased to meet the load bearing capacity requirements of large span steel bridges. As the main method of joining heavy plate steel, welding results in significant residual welding stresses with a complex distribution. Large residual stress during welding will significantly affect the performance of steel bridges. In this work, the distribution of residual stress in a welded thick steel sheet is systematically investigated, a specimen with a thickness of 80 mm was designed and manufactured, and the residual stress of welding was measured by X-ray diffraction.

Keywords: steel bridge, thick steel plate, welding residual stresses, X-ray diffraction method, weld joint

Cement compositions based on slag-Portland cement containing finely ground slag in its composition are considered. Fine-ground slag was obtained by grinding in a laboratory jet mill equipped with an automatic classifier. The upper limit of slag grinding was 20 microns. It was found that the introduction of 1-3% fine-ground slag into the composition of slag-Portland cement made it possible to increase the strength and structural characteristics of cement stone in the early stages of hardening. To ensure the stabilizing effect of finely ground slag particles in the cement matrix, cement compositions were sealed with water with the addition of a sulfonaphthalene-formaldehyde-based plasticizer in an amount of 0.5% of the cement content. In the course of research, it was found that the strength of samples containing finely ground slag and plasticizer increased by 50% at an early age of hardening (1-3 days), by 30% on average at 28 days of hardening, while the porosity of the samples decreased by 19% and 33%, respectively.

Keywords: fine-ground slag, ultrafine grinding, slag-Portland cement, plasticizer, cement stone, strength, porosity, normal density, setting time, degree of hydration

The study findings on the utilization of ethyl silicates for enhancing bitumen properties are showcased. The impact of ethyl silicate grades 28, 32, and 40 on the characteristics of BN 90/10, BN 70/30 construction bitumen, and BND 60/90 road bitumen was evaluated. On the basis of the conducted studies, grades of bitumen and ethyl silicate were selected, the compositions based on which have the best performance. The compatibility of ethyl silicates with bitumen was tested. It has been established that a smaller amount of ethyl silicate is combined with high-quality bitumen. Based on the infra-red spectra, it was shown that there is no chemical interaction between bitumen and ethyl silicate, but a hydrolysis reaction occurs with the formation of hydrogen bonds. It has moreover been determined that ethyl silicates exhibit both plasticizing and structuring effects on bitumen, resulting in improved frost resistance of polymer-bitumen compositions. Requirements for materials aimed at waterproofing of structures for soil and concrete constructions have been developed and presented. In order to increase the low-temperature limit of applicability of polymer bitumen compositions, additives of liquid oligomeric rubbers from the Yaroslavl synthetic rubber plant (SK-1), as well as latexes from the Krasnoyarsk and Omsk plants were studied together with ethyl silicates. Recommendations are given on the use of ethyl silicates in waterproofing mastics and asphalt polymer concrete.

Keywords: bitumen, ethyl silicates, compatibility, properties, plasticizing and structuring additives, waterproofing mastics, asphalt polymer concrete, IR spectra, soil and concrete structures

The expediency of using a finely ground mineral additive from burnt mudstone clay for the production of heat-resistant expanded clay concrete based on Portland cement with a rational dose of the additive of 30...50% by weight of the binder is shown. Compositions of heat-resistant expanded clay concrete with a maximum permissible application temperature of I10 classes in compressive strength up to B15 and an average density of up to 1500 kg/m3 have been developed. The efficiency of the technology for obtaining heat-resistant expanded clay concrete using pre-forced electric heating of the concrete mixture up to 60°C is substantiated and rational technological parameters of electric heating are determined. The residual strength of heat-resistant expanded clay concrete obtained using the developed technology, after short-term heating to 1000oC, exceeds 0.65 of the initial, which is higher than the values for analogues according to SP 27.13330.2017. The coefficient of linear temperature expansion of the developed heat-resistant expanded clay concrete in the temperature range of 200...1000oC varies within 2 ...5,8ˑ10-6 1/oC. The increase in the coefficient of thermal conductivity of the studied concretes with an increase in temperature up to 1000°C is up to 34%. The heat resistance of heat-resistant expanded clay concrete at 800oC, obtained using the technology of pre-forced electric heating of the mixture, was 12, 14 and 15 air heat changes, respectively, at a temperature of pre-forced electric heating of 60, 80 and 90 оC.

Keywords: heat-resistant expanded clay concrete, fine-ground mineral additive, mudstone, thermal conductivity coefficient, coefficient of linear thermal expansion, residual strength

The increasing complexities in the development of new fire-protective coatings hinder the attraction of private investments and impede the progress of innovation. The review provides an overall picture of the research and specifically illustrates the extraordinary diversity of their directions and explains the inherent reason for such diversity. The goal of this review is to establish an information foundation for a critical analysis of the feasibility of private investments in developments in this field and to show some possible ways. The wide range of choices for specific components in fire-protective coatings and the diversity of mechanisms they employ result in a factorial number of possible combinations. The variety of properties of these components and the complexity of their interactions make it difficult to assess the outcomes of their selection unequivocally without conducting experiments during the development of new materials. Therefore, confident prediction of the results of new research is extremely challenging. As a consequence, there is a broad spectrum of directions and sub-directions in ongoing developments. Summing up the results of these investigations is further complicated by the difficulty of testing materials for aging parameters and resistance to external influences. The wide range of choices for specific components in fire-protective coatings and the diversity of mechanisms they employ result in a factorial number of possible combinations. The diverse properties of these components and the complexity of their interactions prevent a definitive evaluation of the results of their inclusion in the composition prior to conducting experiments in the development of new materials. Therefore, confident forecasting of the results of new research is extremely challenging. As a consequence, there is a broad range of directions and sub-directions in ongoing developments. Summing up the results of these investigations is further complicated by the difficulty of testing materials for aging parameters and resistance to external influences. The high uncertainty in forecasting the prospects of specific developments stimulates the advancement of simulation methods for compositions and coating manufacturing technologies, as well as the prediction of their effectiveness, etc. However, these methods only provide a partial increase in the reliability of expectations. A more thorough execution of a feasibility study is recommended to substantiate venture investments. One of the additional approaches capable of enhancing its credibility is the utilization of non-traditional specialized methods for researching patent information.

Keywords: fire-protective coatings, specifically illustrates the extraordinary diversity, prospects of specific developments stimulates, simulation methods for compositions and coating manufacturing technologies

The article is devoted to the issue of increasing the efficiency of ventilation systems through the use of a new type of air ducts. The main advantage of microperforated textile air ducts is the possibility of supplying fresh air with laminar micro jets to the human breathing zone. The need to adapt the existing methods for calculating the main parameters of jets for the laminar regime is noted. The article presents the results on the development of a mathematical model of a stationary boundary layer for the numerical calculation of the movement and heat and mass transfer of air in a laminar microjet. A discrete analog of the generalized differential equation is derived, on the basis of which a software package is developed that allows one to determine the main parameters of laminar microjets. Verification of the developed software package was carried out, the discrepancy with the known engineering method was less than 3%.

Keywords: mathematical modeling, air exchange, microperforated textile air duct, microperforation, laminar jet, control-volume method, round jet, micro jet

A promising direction for improving the durability and transport and operational performance of road pavements is the use of modifiers, including those based on sulfur as a component of the asphalt concrete mixture. However, sulfur and its toxic gases are active substances that can enter into chemical interactions with fillers to form water-soluble calcium and magnesium sulfides CaS and MgS. This process leads to the destruction of the dispersed phase and a decrease in the water resistance of sulfur asphalt concrete. A promising direction that has received wide approbation in the manufacture of polymer composites is the finishing of the filler surface, which makes it possible to prevent the formation of water-soluble sulfides. The coupling agents form a shell impermeable to sulfur, which prevents its chemical interaction with the dispersed phase. The following components are offered as coupling agents: Polymethylsiloxane (PMS-100), SKDN-N rubber, silicic acid sol in a medium containing Fe(OH)3 nanoparticles, and iron (III) hydroxide sol.

Keywords: sulfur asphalt concrete, asphalt concrete, water resistance, strength, sulfur bitumen binders, nanoscale additive

The results of research permissible longitudinal axial and fiber tensions are given for various characteristics of gas distribution and gas consumption systems.

Keywords: polyethylene gas pipeline, longitudinal axial tension, longitudinal fiber tension, gas pipeline deformation, optimal gas pipeline bending radius

The paper presents the results of studies of the characteristics of a polymer coating for the protection of steel and concrete surfaces based on low molecular weight dimethylsiloxane rubber SKTN-A. For cold curing of the binder and its modification, the MSN-7-80 hardener was used, an additional functional additive was galvanic sludge calcined at 1000 °C and crushed to a particle size of no more than 40 microns. It was found that polymethylsilazane, which is part of MSN-7-80, increases the strength characteristics of the coating, especially its cohesive strength, while reducing water absorption by increasing the hydrophobicity of the surface. In turn, galvanic sludge increases the mechanical strength upon impact. The ecological safety of the obtained material was confirmed by the method of biotesting on the mortality of Daphnia magna Straus. As a result of comparison with a protective coating similar in composition and purpose, it was revealed that the coating obtained in this work surpasses it in strength and adhesion characteristics. The developed polymer composition can be used to protect steel and concrete surfaces in construction and mechanical engineering from shock and moisture, including in extreme conditions of high or low temperatures and in contact with aggressive media.

Keywords: polymer composition, protective coating, organosilicon binder, electroplating sludge, polymethylsilazane, cold curing

The article presents a feasibility study of the use of the izoproflex-115A pipeline based on thermal and hydraulic calculations of existing thermal networks in Saransk. When modeling two variants (pipe networks made of steel in polyurethane foam insulation and polymer pipelines "izoproflex-115") of pipelines, the same technique was used. Analysis of the calculation results of the longest section of the heat network showed that ISOPROFLEX pipes, on average, have a three-fold capacity reserve in relation to a steel pipe. The use of modern izoproflex-115A pipeline systems will ensure high-quality and uninterrupted heat supply to consumers, increase energy security and energy efficiency, reduce the accident rate of heat supply systems and improve the financial performance of heat supply organizations.

Keywords: heating networks, pipeline, reserve, capacity, heat supply, consumer, insulation, electronic model, isoproflex-115A, Zulu Thermo

Insulating materials are widely used in the petrochemical, energy and other industries. Thermal insulation materials play an important role in the energy saving of district heating systems and in the construction sector. In this work, the influence of the wetting and drying cycle on the thermal conductivity and density of the heat-insulating material is determined by the experimental method. The thermal conductivity of the insulating material was determined by the protected hot plate method. It has been established that after four cycles of wetting and drying, the thermal conductivity and density of the heat-insulating material increase up to 2 and 2.5 times, respectively.

Keywords: thermal conductivity of heat-insulating materials, density of heat-insulating materials, dampening of heat-insulating materials

In the article, it is proposed to take the density of soil particles as the maximum density, the determination of which does not require sophisticated equipment, is determined in the laboratory using a pycnometer, while the density of soil particles is a fairly stable value, depending only on the composition of the soil. As a result, a more advanced method has been developed for assessing the degree of compaction of sandy soils by using the density of soil particles and statistical dependencies as the maximum soil density without directly determining the maximum density and optimal soil moisture in the laboratory according to GOST 22733-2016. Based on the research of BeldorNIA, it is proposed to take the density of soil particles as the maximum density, the determination of which does not require the presence of complex equipment.

Keywords: highway, soil, soil compaction, soil composition, road surface, road defects, trackage, road construction, method, pycnometer

The experience of standardization of modular construction and factory-ready buildings of China, the USA, Canada, Great Britain, France, the Netherlands, Germany and others is considered. The analysis of the existing profile regulatory and technical documentation (RTD) in the Russian Federation. The analysis of domestic and foreign RTD showed that there is no unified approach to rationing of the considered subject area. At the present time it is necessary to update the Russian RTD in the field of modular construction. Based on the results of the analysis and synthesis of the world practice in the field of modular construction, recommendations and suggestions for working with terms and definitions, the variants of development of normative and technical documentation of the Russian Federation in the field of modular construction and themes of work for the development of modular construction regulation were developed.

Keywords: modular construction, quickly erected buildings, prefabricated buildings, technical documentation