Heat treatment of concrete, along with steaming, is one of the main methods for accelerating the hardening of concrete and achieving its transfer, stripping and design strength. These concrete processing technologies are more often used in factories in the manufacture of mass-produced concrete and reinforced concrete products in curing chambers of periodic and continuous action, under portable hoods on stands and other installations, or in special thermoforms, thermal packs, cassettes, etc. However, there is an increasing need acceleration of concrete strength gain at the construction site at the time of construction and installation works associated with new construction, repair or reconstruction of existing buildings. The aim of the study is to study the acceleration of the strength development of concrete subjected to heat treatment using the energy of an electromagnetic field of microwave frequencies. The article presents the results of an experimental study of concrete samples for compression treated with microwave energy and the control group of samples gaining strength in natural conditions. The experimental data obtained indicate an increase in the strength of the treated concrete samples by 72.94% on day 1, by 27.83% on day 2, by 14.23% on day 3, and by 1.1% on day 7 in comparison with samples not subjected to microwave exposure. From the 14th day, a gradual drop in strength begins in comparison with the samples not subjected to heating with the help of electromagnetic fields, so on the 14th day the strength of the treated concrete samples decreased by 2.45%, on the 21st day by 32.17%, on the 28th day by 25.61%. As a result of the analysis of the obtained experimental data, it was concluded that microwave exposure to the concrete solution significantly increases the strength of concrete in the early stages, but negatively affects the design strength of concrete as a whole.

Keywords: microwave radiation, microwave, concrete, heat treatment, strength, construction

Factors affecting the limited mineral resources of the planet and requiring the expansion of the raw material base of the construction industry are considered. The negative impact of overburden dumps on the ecological state of the habitat was noted. The importance of their processing into a useful product was emphasized in connection with the need to implement the industry program of the Russian Federation ""Involvement of overburden and containing rocks classified as production waste in economic circulation for 2022-2030."" The properties of sand and opoka as raw materials for making foam concrete were analyzed. The result of the analysis made it possible to formulate a list of restrictions, as a result of which it is undesirable to use opoku in concrete of a cast-in-place structure and a list of reasons, based on which it is possible to predict the feasibility of its use in foam concrete. The results of experimental studies are presented, reflecting the influence of the individual properties of sand and opoka on the density of foam concrete mixtures, the density of solidified foam concrete and the kinetics of their plastic strength during three hours of hardening from which it follows that replacing sand with opoka allows significantly improving the technological properties of foam concrete mixtures without compromising the achievement of their design density. It follows from the analysis of experimental data that the structural features of the foam concrete mixtures have a positive effect on the technological properties of foam concrete mixtures, which accelerate the gain of plastic strength of foam concrete mixtures after their placement into molds. The most important reason for the achieved result should be considered mesopores located in the volume of dispersed particles of aggregate from opoka. The established scientific facts make it possible to predict the expanded use of overburden rock - opoki in order to save resources in the construction industry and construction.

Keywords: resource saving, sand, opoka, foam concrete mixture, plastic strength

The article presents the results of a study of the rheological properties of cement compositions with a polycarboxylate-based plasticizer and stone flour from carbonate rocks of the Saratov region.

Keywords: cement, rheological matrix, powder-activated concrete, superplasticizer, hyperplasticizer, finely dispersed additive, stone crushing waste, stone flour, water-cement ratio, water-reducing effect

The influence of the type and dosage of some redispersible polymer powders on the shrinkage deformation of building mortars obtained from dry building mixes, including for underfloor heating, after exposure at a temperature of 70 ° C in accordance with GOST R 56387-2018 was investigated. The introduction of admixtures 4042N, E06RA, 5603 into the mixtures did not lead to an increase in shrinkage deformations when maintained according to GOST R 56387-2018 relative to the additive-free standard, regardless of the type and dosage of the admixture, while with these admixtures, regardless of their dosage, within 1-3%, the values of shrinkage deformations were less than 1.5 mm / m. The greatest influence of the type and dosage of the redispersed polymer powders on the shrinkage change is manifested at the heating stage, which is due to their influence on the kinetics of dehydration and the magnitude of the E-modulus. Depending on the type of cement, type and dosage of the admixture, the moisture loss values by the end of heating to 70oC ranged from 0.114 to 0.629 relative to the total moisture loss by the end of holding. Naturally, a change in shrinkage by the end of heating from 0.027 to 0.595 relative to complete shrinkage by the end of aging was noted, while a proportional relationship between moisture loss and shrinkage was revealed. In some formulations, an expansion of up to 0.469 mm/m was recorded by the end of heating. For a comprehensive assessment of the degree of influence of admixtures on changes in the deformation and strength properties of mortar at a holding temperature of 70 ° C according to GOST R 56387-2018, an indicator of the conditional stress level is proposed, varying depending on the holding stage, type of cement, type and dosage of the additive in the range from 0.489 to 3.05.

Keywords: Shrinkage, building mortars, dry building mixes, redispersible polymer powders, underfloor heating

The influence of the ratio of fly ash and blast furnace slag in a geopolymer binder on the properties of concrete hardening during heat and humidity treatment was studied. The article obtained data on the influence of the binder composition on the workability of the concrete mixture, the strength and shrinkage of concrete. The dependences of the influence of hardening temperature and the proportion of slag in the binder on the strength of geopolymer concrete were established. The results obtained made it possible to recommend the studied binder and concrete based on it for pilot industrial production of prefabricated reinforced concrete.

Keywords: geopolymer binder, fly ash, blast furnace slag, concrete, strength, workability, water absorption, shrinkage

For last 10 years creating of new patents in the field of nonisocyanate polyurethane have passaged Chinese inventors. Chinese inventions in the field of NIPU consist about 15% all such inventions, but that are not pioneer ones, especially for foam application.

Keywords: patents, nonisocyanate polyurethanes, oligomeric cyclocarbonates

The technological process of manufacturing self-adhesive radio-absorbing materials is considered. The technological mode of manufacturing radio-absorbing materials consists of two operations – the preparation of a mixture and the production of radio-absorbing materials from the resulting mixture. An important step is mixing the mixture. The quality of the radio-absorbing material depends on the quality of the mixture.

Keywords: mixture, mixing time, scanning probe microscope, microstructure study

The effectiveness of fly ash from the Novo-Irkutsk Thermal Power Plant and ash and slag mixtures from Thermal Power Plant-10, formed during the combustion of solid fuel fossils of JSC Irkutskenergo, in the composition of cements with low water demand has been shown. The chemical composition and physical and technical properties of this waste have been determined. The grindability was studied and the specific energy consumption of cements with different ash contents (30-70%) was calculated. It has been established that low-water-demand cements with fly ash and ASM are not inferior to Portland cement in technological and physical-mechanical indicators, and can be recommended for use in construction.

Keywords: large-tonnage waste, ash and slag mixtures, grindability, low water demand cement, superplasticizer, joint grinding

A review of studies of photovoltaic chromatic devices for regulating the transparency of glass and simultaneous generation of electrical energy through an internal photoelectric effect is given. Devices based on thin-film heterostructures with kesterite as a photocell are considered in detail. Kesterite is an absorbing material consisting of copper, tin, zinc, sulfur and selenium, a new promising material for creating "smart" glazing with adjustable transparency. The energy characteristics of coatings based on kesterite are compared with coatings of other types. The prospects of kesterite as a basis for creating effective autonomous photovoltaic windows of adjustable transparency are shown.

Keywords: photoelectric effect, transparency, glass, kesterite, perovskite, silicon, window, energy efficiency, electrochromic effect

The researches directed on control by gelation, regulating of composition and properties of swelling up fireproof composite coatings (fireproof composites) for security of fire-resistant building constructions are presented. In-process on the basis of the topological analysis and gelation modelling component composition schungite in fireproof aggregates with demanded thermal and hardness in performances is optimised. The interconnection of structural performances, modifications of mineralno-phase composition and properties of fireproof aggregates is experimentally positioned at high-temperature impact. The rated-analytical method positions efficiency of fireproof aggregates for raise of flame-resistance of reinforced concrete constructions. The obtained data have allowed to develop representations about the gelation gear at interacting of corpuscles schungite in swelling up cement system at high-temperature heat and justify to approach to creation of effective fireproof aggregates for fire-resistant building constructions.

Keywords: fireproof composites, swelling up coatings, schungite, granulometry of components, composition optimisation, structure modelling, gelation of aggregates, mineralno-phase composition, properties of composite, fire-resistant of constructions

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