The article considers the problems of using construction materials of improper quality in Russia. The concepts of sub-standard, fraudulent and counterfeit construction materials (SFC materials) are defined. The distinctive features of SFC products in the construction materials market and the consequences of non-compliance with general requirements for their quality are highlighted. Features of digital marking of construction materials in Russia are analyzed. Key problems of incoming inspection made by the contractor and their causes are highlighted. In conclusion, recommendations are given to improve the efficiency of the incoming inspection system for construction materials.

Keywords: construction materials, quality, fraudulent products, counterfeit products, labeling, safety of buildings and structures, construction control, incoming inspection

The article provides a justification for the concept of a folding system for a prefabricated residential module based on wooden structures. An analysis of foreign analogues of prefabricated transformable wooden buildings and an assessment of the possibility of their use in northern climatic conditions has been performed. A transformation system for a prefabricated wooden module for use in northern and Arctic conditions is proposed and substantiated.

Keywords: low-rise housing construction, transformation, transformation of low-rise residential buildings, prefabricated transformable buildings, pre-manufactured at the factory, high degree of factory readiness

The article shows the possibility of obtaining an epoxy-containing adhesive composition using fibrous magnesium hydrosilicate of the composition Mg3Si2O5(OH)4 as a reinforcing filler. The fibrous filler is selected as a reinforcing component to impart adhesive strength to the adhesive joint between the glued surfaces of a wooden beam.Higher values ​​of the adhesive joint strength limit were obtained for the epoxy-containing composition using Mg3Si2O5(OH)4 fibers.

Keywords: adhesive composition, composition, epoxy resin, polyethylenepolyamine, polyethylenesiloxane, polyvinyl acetate, Kleiberit, water resistance, saturation, load, tensile strength, testing, properties

The results of studies of the strength properties of plaster solutions with vermiculite on a mixed binder using a multifunctional additive D-5 are presented. A slight acceleration of the setting time of solutions with a multifunctional additive D-5 was found, while the bending and compressive strengths of the solutions did not change significantly after 2 hours and 28 days. Replacing part of the expanded vermiculite fraction 0 – 0.315 mm with volcanic pumice fraction 0 – 0.315 mm in the construction mortar allows to significantly increase their strength characteristics and reduce the cost without a noticeable increase in density. Expressions of the dependence of the compressive strength of the mortars on the calculated total porosity are obtained.

Keywords: construction gypsum, Portland cement, volcanic pumice, expanded vermiculite, D-5 multifunctional additive, plaster composites, compressive and bending strength

Adhesive joints of reinforcing rods and wood are the weakest point in reinforced wooden structures, since they have low shear resistance of the reinforcing rod and contribute to the development of plastic deformations of wooden elements. To achieve elastic operation and increase adhesion to the rods, a reinforced adhesive compound with the inclusion of quartz sand is used. This article examines the operation of a reinforced adhesive joint with various types of core fittings – steel periodic profile, smooth steel and fiberglass. The work of the adhesive joint in solid and glued wood was also recognized as an important factor for the operation of the reinforced adhesive composition. Experimental studies are confirmed by graphs and tables of numerical results, which allows us to establish the reliability of the results obtained and conclude that it is necessary to improve certain methods of manufacturing reinforced wooden structures.

Keywords: rebar, reinforcing bar, reinforced wooden structure, pulling out, wooden structure, wood, glue, adhesive joint, strength, epoxy resin

Fiberglass core reinforcement could find its application in wooden structures due to a number of specific practical advantages not inherent in steel rods or other types of reinforcement. However, due to the weak adhesive properties of the surface of fiberglass rods, their full-fledged joint work with wood as a single body is not observed. The study suggests some ways to increase the strength of the adhesive joint of fiberglass reinforcement and wood, such as applying quartz sand to the surface of the rods, grinding the surface of the rods, as well as adding sand-resin casting molds to the adhesive composition. Tests of each of these methods were carried out and the results obtained were compared with the initial model of the adhesive joint, as well as with the calculated model of the adhesive joint in order to determine the most effective method.

Keywords: adhesion, reinforcing rod, pulling out, wood, adhesive joint, adhesive composition, bearing capacity, strength, fiberglass rod, epoxy glue

The article presents a comparative analysis of the results of verification calculations of a monolithic reinforced concrete floor slab and full-scale tests, and also formulates the main factors affecting the accuracy of determining the bearing capacity of monolithic reinforced concrete structures when performing verification calculations. In accordance with regulatory documentation, the bearing capacity of building structures is determined by performing verification calculations according to current design standards and conducting full-scale tests (if necessary) to confirm the bearing capacity established by the calculations. In modern practice of technical inspection, full-scale tests are extremely rare due to their high labor intensity and the complexity of interpreting the results. However, it is full-scale tests that allow the most accurate determination of the bearing capacity of a structure. This makes it possible to correctly assess the technical condition, optimize the development of strengthening projects due to a reasonable choice of method, accurate calculation of the required volumes of work and, as a result, minimize material costs.

Keywords: bearing capacity, full-scale tests, verification calculation, reinforced concrete, floor, deflection, limit state groups, technical inspection

The article presents an analysis of methods for strengthening reinforced concrete columns without changing the original design scheme. The calculation of reinforcement with a metal collar, a reinforced concrete collar, using prestressed struts and reinforcement with composite materials under central and eccentric compression is performed. A comparative analysis of the technical indicators of the considered reinforcement methods is made. A strategy for selecting a method for strengthening reinforced concrete columns is formed. An analysis of the optimal areas of application of various methods for strengthening reinforced concrete columns shows that the choice of a specific technology should be determined by the nature of their stress state depending on the magnitude of the eccentricity of load application. This study confirms that there is no universal "best" method for strengthening reinforced concrete columns; each of the considered methods has its own advantages and disadvantages. The results allow choosing optimal solutions based on the criteria of efficiency, reliability and cost-effectiveness.

Keywords: columns, reinforced concrete, steel, reinforcement, frame, carbon fiber, comparison, optimal method

The article presents the results of laboratory testing of a precast lintel made of D600 aerated concrete blocks fastened together using assembly adhesive for laying aerated concrete blocks and three reinforcing bars, two bars in the lower zone with a diameter of 20 mm A400 and one bar in the upper zone with a diameter of 16 mm A400. When testing the beam lintel, 3 loading schemes were assembled, each of which was a beam hinged on concrete supports. The obtained data were analyzed. Based on the test results, destructive loads, the nature of destruction were determined and the resulting deformations were assessed. The nature of destruction is similar to that of reinforced concrete beam structures with insufficient transverse reinforcement; destruction in all tested prototypes occurs in the support zone along inclined sections. The bearing capacity of aerated concrete lintels made of piece material is sufficient for use in construction practice.

Keywords: testing, bearing capacity, reliability, deformability, gas blocks, lintels, destruction

The article examines methods of surface stabilization of loess slopes subject to erosion and landslides. The authors consider the use of soil concrete based on slag-alkaline binder using local loess as a filler. Experiments were conducted with various binder compositions, including liquid glass with different modules and sodium hydroxide, which made it possible to determine the optimal parameters for achieving high strength and frost resistance. For decorative purposes, the use of natural pigments, such as siderites, providing color stability, is proposed. The practical part of the work includes a description of the technology of pneumatic spraying of soil concrete to create monolithic lattice structures.

Keywords: loess slopes, soil concrete, slag-alkali binder, liquid glass, frost resistance, pneumatic spraying, decorative pigments

The stability of inorganic ultraviolet pigments synthesized from phosphogypsum in relation to the action of a number of solvents has been studied. It is noted that under the conditions studied, the samples are stable in the presence of water and solutions of organic solvents, and treatment of the samples with concentrated solutions of sulfuric acid and sodium hydroxide leads to a decrease in luminescent properties. The luminescence ability of the samples remains when heated to 800 ° C. Based on the developed pigments, building mixes can be obtained that have luminescent properties when irradiated with ultraviolet light.

Keywords: building mixes, putty, luminescent pigments, phosphogypsum processing, thermal stability, solvent treatment, action of acid and alkali solutions

The impact of various types of loads on the integrity of the insulating shell is being evaluated and proposals are being developed to improve the operational resistance of light mineral wool slabs in the pitched roof structure. The result of the research was the development of mineral wool products with an alkali-resistant glass mesh reinforced outer layer. The operational resistance of the insulating shell increases by 1.7 times compared to light slabs based on stone wool and by 2.4 times compared to slabs made of glass wool.

Keywords: mineral wool plate, thermal insulation material, stone wool, glass wool, erosion of the product, temperature effect, humidity effect, air flow, operational stability, energy efficiency

The authors of this article raise the issue of the correct selection of internal material for sandwich panels. The use of these structures is widespread in the construction of industrial facilities, so it is important to consider all the parameters of possible options for the optimal choice. The authors define the objectives of the article as the creation of an auxiliary comparative table with the parameters of the most popular thermal insulation materials for sandwich panels based on regulatory and theoretical information, as well as the formulation of recommendations for the use of a certain material depending on the specified conditions. Particular attention in the study is paid to such properties of materials as moisture resistance, flammability, durability, density and thermal insulation. It is also important to note that the article touches upon the cost issue, namely, market prices for sandwich panels are compared with the considered insulation materials of some suppliers.

Keywords: thermal insulation materials, sandwich panels, properties of materials, analysis of properties, moisture resistance of structures, density

The article considers the issues of improving the technology of preparing concrete mixtures for road surfaces at existing concrete mixing units without additional costs for their technical re-equipment. The essence of improving the preparation of concrete mixtures lies in the complex use of carbonate microfiller and superplasticizer additives in combination with the developed innovative method of preparing concrete mixture. The article shows that when using a polycarboxylate superplasticizing additive and a microfiller based on porous shell limestone in combination with the proposed method of preparing concrete mixture, it is possible to obtain road concrete with the required strength properties with a cement consumption reduced by 50 kg/m³.

Keywords: road concrete, superplasticizer, mineral micro filler, method of preparation of concrete mix

Disposal of drilling waste in construction The methods of disposal of drilling waste are considered and the mechanisms of their biological purification by microorganisms are described. A technology for the disposal of biologically purified drilling mud is proposed by manufacturing concrete structures of marine artificial reefs, barrier breakwaters and other products on an offshore platform. Compositions of fine-grained fiber-concrete mixtures have been developed, including Portland cement, biologically purified well drilling waste, basalt fiber fibers and superplasticizer "SP-3". The sufficiently high parameters of the strength characteristics and frost resistance of the obtained fiber concrete compositions have shown the possibility of their use in harsh climatic conditions. materials.

Keywords: drilling waste, biodegradation, fine-grained fiber concrete, dispersed reinforcement, mechanical properties, offshore platform

The article examines the features of dismantled paving slabs as raw materials for the production of recycled aggregate for concrete. The effect of crushed fine fractions of secondary crushed stone screenings on the properties of fine-grained self-compacting concrete was investigated. It was experimentally shown that the use of this material as a mineral additive leads to an increase in the water demand of the self-compacting fine-grained mixture and a significant decrease in strength.

Keywords: demolition waste, vibro-pressed paving slabs, recycling, screening of secondary crushed stone, mineral additive, self-compacting fine-grained concrete, consistency of concrete mix, strength, shrinkage

The importance of recycling construction waste for the development of closed-loop economy technologies in the construction industry is considered. The effect of replacing high-quality granite and limestone crushed stone with secondary aggregate obtained by crushing concrete scrap on the strength properties of geopolymer concrete was investigated. It was established that such a replacement does not lead to a decrease in the strength of such concrete, and the impact resistance increases significantly.

Keywords: demolition waste, concrete scrap, recycling, geopolymer concrete, blast furnace granular slag, crushed stone crushing screening, closed-loop economy technologies, secondary aggregate, strength, impact resistance

The use of the contact angle as a criterion for the degree of hydrophobization of a solid surface and gypsum particles in suspensions containing surfactants showed that an increase in the concentrations of ethyl silicone oil and soap naphtha in the initial gypsum suspensions led to an increase in the contact angle of wetting of solid particles to 82.5° and 77.5°, respectively. However, on the surfaces of the formed solid samples containing ethyl silicone oil, a drop of water spreading and its rapid absorption were observed. Solid samples containing soap naphtha in an amount of 3% had a hydrophobic surface characterized by a contact angle of 82.2°. Probably, the hydrophilic and hydrophobic properties of the solid surface of the material are determined by its bulk structure at the stage of formation, including under wave action. In this case, the porous-capillary structure of the formed samples containing gypsum and surfactants affects the determination of the wetting criterion.

Keywords: contact angle, hydrophobization, gypsum, soap naphtha, ethyl silicone oil, ultrasonic treatment

In the production of bitumen-mineral mixtures, it is proposed to use artificial granite as a filler - waste from the production of porcelain stoneware (OPK). To assess the durability of road and pavement network coatings, a method for determining the aging coefficient of bitumen-mineral mixtures was developed. It was concluded that in the presence of sand from the screenings of crushed porcelain stoneware, the bitumen binder of fine-grained BMS is less susceptible to aging processes.

Keywords: artificial granite, aging of bitumen binder, aging coefficient, sand from crushing screenings

The article describes the process of sedimentation in water treatment, as well as the formation of tap sludge. A new method of water supply sludge treatment with coagulant regeneration at high turbidity of initial water is proposed. On the basis of the conducted research it is revealed that the greater the coagulant consumption obtained by the sulfatization method, the better the degree of coagulation. The basic technological scheme of water sludge processing by sulfatization method is developed. It is suggested that the obtained coagulant from water supply sludge can be used for repeated preliminary sedimentation. Taking into account the urgency of the problem of providing the population with clean drinking water, it is recommended to conduct pilot testing of the obtained coagulant from tap sludge by the sulfatization method.

Keywords: water treatment, tap sludge, daily regulation basin, sedimentation, turbidity, sulfatization method

The paper presents the results of research into the efficiency of fine-grained concrete made using substandard materials and complex modifying admixture. The aim of the work is to evaluate the effect of multicomponent admixture on strength characteristics and efficiency of concrete. For this purpose the fractional factor experiment with variation of seven factors was applied, which were: microsilica, superplasticizers and other additives influencing both the properties of fine-grained concrete mixture and the properties of fine-grained concrete. The main criteria for assessing the influence of complex modifying admixtures were taken as the coefficient of structural quality and specific cement consumption per unit strength. The conducted research allowed to establish that the optimal composition of the additive increases the CQC by 29.9% and reduces the specific cement consumption by 24.6% in comparison with the control samples. It is shown that a balanced combination of additives improves the performance properties of concrete, contributing to resource saving and reducing the environmental load.

Keywords: fine-grained concrete, substandard materials, complex modifying admixture, structural quality coefficient, specific cement consumption, mathematical planning of the experiment, resource saving, compressive strength

The effect of nanosized boehmite microadditives on the surface properties of carboxymethyl cellulose polymer suspensions with aluminum microparticles was studied. It was found that with an increase in the boehmite content from 0.10 g to 0.20 g in suspensions, the surface tension of liquid systems increases by 8 mN/m. The contact angle of the liquid composition wetting the fluoroplastic surface also increases: from 62 ° to 85 °. It is shown that on a low-energy fluoroplastic surface, boehmite nanoparticles act as a pore-forming agent, leading to the generation of ordered cells on the surface of films formed from suspensions. The morphology of the initial powders and the formed films with cells was studied using optical and electron microscopy. It was established that ordered cells of similar size with dimensions of ratio 500 to 1,000 microns in size are formed with a boehmite content in the base composition of 0.15 g.

Keywords: carboxymethyl cellulose, aluminum powder, nanosized boehmite, suspension, surface tension, wetting angle, pore

The reuse of ash and slag waste from coal combustion is of great economic and environmental importance. The most material-intensive area of their reuse is the stabilization of ash and slag mixtures with Portland cement for the construction of layers of highways. A technical understanding of the processes of structure formation in stabilized ash and slag mixtures makes it possible to regulate the final properties and quality of the layers of road clothing and the roadbed. Strengthening of ash and slag mixtures with Portland cement makes it possible to increase the physical and mechanical properties of ash and slag mixtures: strength, frost resistance, density, etc.

Keywords: ash and slag mixtures, stabilized ash and slag mixtures, structure formation of stabilized ash and slag mixtures, sportland cement, microstructure of the ash and slag mixture

We conducted experimental studies to determine the thermal conductivity of polyurethane foams with different structural parameters, such as cell type and size. The purpose of the study was to investigate the contribution of radiant heat exchange to the thermal conductivity of polyurethane foams. The studies were conducted using the ITP-MG4 thermal conductivity meter in two distinct versions. In the first instance, the thermal conductivity of polyurethane foam was measured without the inclusion of a foil layer, whereas in the second instance. The results of the studies demonstrated that, depending on the morphology of the foam, the contribution of radiant heat exchange to thermal conductivity ranges from 5.88% to 15.87%.

Keywords: cellular materials, thermal insulation, polyurethane foam, thermal conductivity, radiation, morphology

The work investigated the effect of the complex application of the nanomodifying additive "Taunit-M", superplasticizer SP-3 and steel fiber "Mixarm" with a diameter of 1 mm and a length of up to 54 mm. The dependence of the amount of introduced steel fiber on the strength characteristics of concrete was established. Data on the stability of the suspension of mixing water with a nanomodifier are given. An improvement in the intensity of concrete strength gain in the early stages of hardening from the introduced complex nanomodifying additive was determined.

Keywords: concrete, carbon nanotubes, ultrasonic dispersion, steel fiber, suspension stability, superplasticizer