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 discusses the surface-active properties of casein and its potential for use as a bioorganic additive in repair and restoration compounds (RRC). An analysis of literary sources confirming the amphiphilic nature of casein, its ability to stabilize interfacial systems and form stable micelles is carried out. The results of an experimental study of the dependence of the surface tension of aqueous solutions of casein on its concentration, carried out by the hanging drop method on a DSA-100 tensiometer, are presented. It is shown that casein effectively reduces the surface tension of an aqueous solution, especially at concentrations of up to 4–5%, which confirms its active adsorption at the phase boundary. Based on the obtained surface tension isotherm, the predicted wettability is considered based on the Young equation. The data obtained emphasize the prospects of using casein as a natural surfactant for creating environmentally friendly and authentic restoration materials that meet the requirements of construction and restoration.

Keywords: casein, surfactants, repair and restoration compounds, surface tension, wettability.

Reinforced concrete structures (RCS) operating under the natural conditions of the Far North are subjected to alternating freezing and thawing. The impact of freezing–thawing cycles (FTC) leads to the degradation not only of the strength but also of the deformation properties (DP) of concrete. In the current design standards for RCS, the DP of concrete and reinforcement are specified as average statistical values. This study investigates the influence of the variability of concrete’s deformation properties on the reliability of the load-bearing capacity of flexural reinforced concrete elements before and after exposure to FTC. It was shown that considering the variability of concrete’s deformation characteristics at reinforcement ratios up to 1% under alternating temperature conditions has practically no effect on the load-bearing capacity, while at reinforcement ratios close to the limiting values it leads to its reduction. In addition, recommendations were provided for the design of flexural reinforced concrete elements under alternating temperature conditions.

Keywords: freeze-thaw cycle, statistical regularities of resistance, flexure, reinforced concrete, ultimate deformation of concrete, assurance

Fiber concrete is one of the most promising building materials. However, it is most commonly used in finishing materials, small architectural forms, industrial floors, and decorative facade details, and is less commonly used in load-bearing structures. Meanwhile, the use of fiber concrete, including fiber reinforced concrete, in load-bearing structures is limited due to a lack of information about the material's behavior under load, and additional experimental data is needed for theoretical understanding. The article discusses experimental studies of concrete reinforced with polypropylene fiber for compression and central tension. Qualitatively different patterns of destruction of concrete and fiber concrete samples were identified. The analysis of the results showed that the highest peak load values were observed in samples with a 1% polypropylene fiber content. Compared to the control series, the load-bearing capacity increased by up to 45%. 

Keywords: fiber concrete, fiber, polypropylene fiber, compression tests

Concretes based on ground blast-furnace granulated slag activated with alkaline solutions exhibit excellent mechanical properties. However, they have significant drawbacks, such as rapid setting and poor workability during concreting. The effect of various superplasticizers on the properties of pastes prepared from ground blast-furnace granulated slag activated with alkaline solutions was studied. An aqueous solution of sodium silicate and sodium hydroxide was used as an alkaline slag hardening activator. The effect of superplasticizer dosage on the setting time, flowability, and changes in compressive strength of slag-alkali solutions was studied. It was found that properties of the freshly prepared paste, such as the initial and final setting times, increase with increasing the solution-to-slag ratio and with the addition of a superplasticizer. Superplasticizers based on naphthalene sulfonic acid and polycarboxylate ether were found to effectively influence both the setting time, workability, and strength of slag-alkali binder-based compositions. It was established that a slag-alkali composition with a mortar-to-slag ratio of 0.4 exhibits low workability and is not technologically feasible for on-site concreting, while its optimal value is 0.5. A superplasticizer dosage of 2% of the slag mass ensures not only the technological requirements for concreting (the initial and final setting time and concrete mix mobility), but also the strength properties of the formed concrete based on ground blast-furnace granulated slag.

Keywords: metallurgical waste, granulated slag, hardening activator, binder, superplasticizer, setting time, spray, strength

The compositions of self-compacting fine-grained concrete using mineral additives such as silica, limestone flour and trepel, as well as polycarboxylate superplasticizer, have been studied. The main attention is paid to the effect of the composition of the mixture on the compressive and flexural strength, density, water resistance and frost resistance of concrete. The test results showed that samples with silica demonstrate increased strength, while the introduction of trepel and limestone flour reduces this indicator. The highest density and frost resistance (F600) were achieved in formulations with silica, without additional additives. The work highlights the importance of optimizing the grain composition of aggregates and the choice of plasticizers to improve concrete performance.

Keywords: self-compacting concrete, fine-grained concrete, silica, polycarboxylate superplasticizer, limestone flour, trepel, strength, density, frost resistance, water resistance

Modern road surfaces are subject to intense wear due to the effects of studded tires and deicing agents, which leads to significant economic losses. In Russia, the annual damage from such wear is estimated at hundreds of billions of rubles. To increase the durability of asphalt concrete, methods for modifying bitumen binders are being investigated, including the addition of rubber chips, polymers (SBS, EVA) and modified sulfur.
The most promising direction is the use of modified sulfur, which improves wear resistance, crack resistance and stability.
to deicing reagents. The article describes in detail the process of obtaining modified sulfur, including degassing and modification with 5-ethylidene-2-norbornene (ENB). Laboratory tests have shown that the optimal sulfur content in bitumen is 25-30%, while 30% demonstrate the best characteristics: increased heat resistance, shear stability and adhesion to mineral aggregate.
The results of IR spectroscopy confirmed the physical mixing of sulfur with bitumen without chemical reactions. The use of modified sulfur makes it possible to increase the service life of road surfaces and reduce repair costs, which is especially important in the context of an increasing sulfur surplus in the Russian Federation.

Keywords: road surface, asphalt concrete, wear resistance, wear gauge, studded tires, modification, degassing, sulfur, bitumen binder, ecology

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

Within the framework of this article, experimental studies of concrete reinforced with polypropylene fiber of two geometric dimensions of 6 mm and 12 mm are presented. Studies were carried out on samples of cubes 10 × 10 × 10 cm and samples of prisms 10 × 10 × 40 cm. In total, more than 100 samples were tested. The objectives of the experimental study: testing fiber concrete samples for compression, analyzing the results obtained, identifying changes in strength and deformation characteristics as a result of fiber reinforcement. Tests of the samples showed an increase in strength of up to 20%, as well as the effect of the percentage of fiber reinforcement on strength properties. The limit percentage of fiber reinforcement was determined, when exceeding which a decrease in strength properties occurs

Keywords: polyarmoured fibre concrete, fibre concrete, low-modulus fibre, polypropylene, strength properties

The article considers the influence of surfactants on the physicochemical and technological properties of repair and restoration solutions, mixtures and compositions and the areas of their application. Particular attention is paid to the mechanisms of interaction of surfactants with solid and liquid phases in repair composites, including the processes of hydrophobization and hydrophilization of surfaces, adsorption, peptization and change in the contact angle. The influence of surfactants on the value of water demand, strength, water resistance and frost resistance of binders, mixtures and compositions is described. The parameters determining the efficiency of surfactant application, as well as quantitative estimates of the surface of dispersed components and their effect on the consumption of additives are given.

Keywords: surfactants, repair and restoration solutions, hydrophobization, hydrophilization, wetting, adsorption, rheology, water demand, additives

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, polyethylenepolyami

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