The paper presents the results of research on the application of gypsum hydrate cakes, the waste products of the refining process at the Krastsvetmet non-ferrous metals plant, for the production of construction materials. The study examined pasty cakes for use in building mortars, and after drying and grinding, the resulting cake powder was further used as a fine filler in asphalt concrete mixes. The optimal composition of the construction mortar was determined using a mathematical method of experimental design. The construction mortars were prepared based on cement and local mineral materials. The study demonstrated that it is possible to get construction mortars of the required strength based on the cakes. The cake powder obtained after drying was examined as a mineral powder for asphalt concrete. Tests showed that the cakes met the requirements for grade MP-3 mineral powders in all aspects. Asphalt concrete incorporating the cakes also met the regulatory standards for its key properties. Based on the research results, the optimal compositions of mortars and asphalt concrete were recommended for implementation to construction companies in the Krasnoyarsk Krai.

Keywords: waste products, cakes, construction mortars, compositions, properties, regression equations, durability, water retention capacity, segregation, mineral powder, asphalt concrete

The impact of the alkali NaOH on the structure and morphology of cellulose has been considered. Using X-ray spectroscopic microanalysis and electron microscopy, it has been determined that treatment of wood cellulose with aqueous solutions of NaOH allows to reduce the content of lignin in cellulose and significantly improve the topography of the fibers. A comparative analysis of alkali cellulose samples was conducted, obtained during treatment with NaOH solutions of 13.7% and 12.3% concentration for a process duration of 5.5 hours, at a temperature of 124 °C. It has been established that at the considered concentrations of NaOH, approximately ~75% and ~50% of lignin is removed from the original cellulose, respectively. The results of infrared spectroscopy indicate an increase in the amorphization of alkali cellulose. Alkali cellulose, formed at a NaOH concentration of 13.7%, exhibits superior morphological uniformity and a lower lignin content.

Keywords: wood cellulose, chemical treatment, alkalinity, lignin, X-ray spectral microanalysis, electron microscopy

The article examines the influence of various superplasticizers on the performance characteristics of concrete. A series of tests of samples-beams of fine-grained concrete modified with plasticizers of various types was carried out. The optimal amount of the introduced additive was experimentally determined to compare the plasticizing effect of the cement-sand mixture. Experimental data are given indicating the main operational characteristics of the material depending on the additive used. The most effective additive "Polyplast SP-3" has been determined.

Keywords: concrete, fine-grained concrete, mixture, lignosulfonates, polycarboxylates, naphthalene sulfonates, plasticizer, superplasticizer, water demand, plasticity

The influence of secondary crushed stone on the strength and shrinkage of concrete was studied. The results showed that when granite coarse aggregate is replaced with crushed recycled concrete, the compressive strength of concrete is reduced by an average of 20% and the flexural strength by 3-10%. Concrete on recycled crushed stone has a high shrinkage. The shrinkage of concrete with a minimum consumption of recycled aggregate differs slightly from the shrinkage of concrete on granite crushed stone.

Keywords: demolition waste, concrete scrap, recycling, recycled aggregate, compressive strength, flexural strength, shrinkage

The article presents the results of the effect of replacing a part of cement with volcanic ash on the strength of cement stone in building mortars. Pozzolan additives have hydraulic properties. Volcanic ash from Kabardino-Balkaria deposits can be used in building mortars and concrete mixtures as an active mineral additive.

Keywords: volcanic ash, active mineral additive of natural origin, building mortars with active mineral additives, cement stone, flexural and compressive strength

This article presents the developed compositions of dry mortar mixtures for the preparation of fine-grained concrete. For the preparation of these mixtures, the technology of electromagnetic action on the dry components of solutions was applied. As a result of the use of a magnetic field to activate and increase the reactivity of the mixture, the physical and mechanical characteristics of fine-grained concrete have significantly improved. The increase in the compressive strength of the samples reached more than 70% compared to the strength of samples prepared using conventional technology without the use of magnetic treatment of dry components of the mixture.

Keywords: dry mix, magnetic treatment, linear induction rotator, fine-grained concrete, strength

The article shows the possibility of reducing the water demand of clinker binders based on gypsum-free cement with a multicomponent additive of technical lignosulfonate and an aqueous solution of sodium silicate. The possibility of obtaining composites based on modified gypsum-free cement with improved properties for building structures has been demonstrated.

Keywords: composite, gypsum-free cement, composition, technical lignosulfonate, concrete, Portland cement, sodium silicate, strength

The article discusses the existing methods for calculating the strength of a normal section in multilayer bending structures. The experience of Russian and foreign researchers was analyzed, the approaches described in domestic and foreign regulatory documents were compared, and key differences were identified. At the same time, special attention is paid to the mathematical description of the work of concrete as a material. It was concluded that further research is expedient to find the most optimal method for calculating multilayer structures.

Keywords: concrete, reinforced concrete, multilayer structures, calculation method, bending element, normal section, stresses, high-strength concrete, stress diagram, description of concrete work, bending moment, neutral axis

The article shows the possibility of producing a composite using carbon black as a filler. Trivalent chromium oxide was chosen not only as a pigment component, but also as a light stabilizer. The results obtained allow us to say that the dispersed composition is efficient. Compositions based on carbon black and containing trivalent chromium oxide in an amount of 1% exhibit electrically conductive properties.

Keywords: pyrolysis carbon, chemical composition, structural and morphological characteristics, elemental composition, energy dispersive spectrum, micrograph, epoxy binder, polyethylene polyamine, trivalent chromium oxide, thermal conductivity, electrical conductiv

This article is a study of the physical and mechanical characteristics and wave parameters of porous fibrous materials (PFM) used in providing sound insulation and vibration protection of buildings and structures. In the work, the classification of porous-fibrous materials according to the initial raw material and various degrees of rigidity is carried out, the main physical and mechanical characteristics and wave parameters of porous fibrous materials, and theoretical methods for their determination are presented. The results of laboratory measurements of the physical-mechanical and wave characteristics of PFM samples (glass and stone bases of various density and thickness) are presented. An extensive experimental study has been carried out in order to evaluate the main relationships between the sample material, its density, feedstock, structure, size, and its acoustic, physical-mechanical and wave characteristics. The results of the study are of great practical importance for the development of acoustically effective building materials and their optimal use in construction and engineering systems.

Keywords: acoustic measurements, acoustic design, building materials, characteristics of porous-fibrous materials, sound insulation, vibration protection of buildings and structures

Utilisation a waste of stone processing in production of other kinds products is an actual task for stone-cutting enterprises. In this study, the possibilities of using basalt dust generated during sawing, grinding and polishing of basalt and related minerals in the manufacture with concrete are studied. Three groups were prepared with different content of basalt dust - 0 %, 5 % and 20 %. After the final hardening performance of the concrete, the compressive strength testing was conducted on the specimens. The results showed that the addition (5%) added basalt dust practically did not reduce the strength ratio practically, the increase of basalt dust content up to 20% caused an average 16% reduction in the strength of the specimens. The fracture character that occurred in the specimens containing basalt dust corresponded to the fracture character that happened to similarly shaped concrete products.

Keywords: concrete, stone waste, strength, basalt

Welding is the main method of joining plate steel. Its use leads to significant residual welding stresses. Residual stress can significantly affect the load-bearing capacity of long-span steel bridges. In this work, a finite element calculation of residual welding stresses of steel sheets up to 100 mm thick was carried out, and the distribution of surface residual stresses and the influence of sheet thickness on the residual surface stress were identified.

Keywords: steel bridge, plate steel, welding residual stresses, finite element method, welded joint, stress distribution

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