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No 1-2 (2026)
Статьи
Investigation of heavy concrete hardening processes under condition of alternate freezing and thawing during winter concreting. Part 2
Abstract
The paper presents the results of comprehensive experimental investigations of the microstructure of cement concretes taken from monolithic structures that exhibited frost-induced deterioration during concreting under severe sub-zero temperatures. The tests were carried out using direct methods for determining the strength properties of specimens at early and long-term curing stages (over 800 days), including samples extracted from frost-damaged reinforced-concrete ele-ments and laboratory specimens subjected to artificial freezing. The structure of the cement paste was examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The study reveals changes in the morphology of hydra-tion products in the cement matrix of the frost-damaged concrete; qualitative and quantitative analyses were performed on samples obtained from different height levels of the cores. The quantitative contents of the main structure-forming crys-talline hydrates–calcium silicate hydrates (C–S–H), calcium sulfoaluminate hy-drates (ettringite and monosulfate), portlandite, and others –were identified and evaluated. It was established that concrete subjected to frost deterioration is ca-pable of significant strength gain at later curing stages. This finding contributes to understanding the mechanism of frost damage and supports the development of effective methods for the rehabilitation and strengthening of reinforced-concrete structures.
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The composition and structure of sand lime concrete as a factor of corrosion resistance with exposed to sodium chloride. Part 1. Structure at the macro- and micro-scale level as a permeability factor
Abstract
The article is devoted to the study of the structure of lime sand concrete based on a lime-silica binder, depending on the initial activity of the raw material mixture and its effect on the kinetics of absorption of chlorine ions under the influence of alternating wetting and drying in a solution of sodium chloride. Lime sand concrete samples were made from mixtures of quartz sand and lime-silica binder, the CaO activity of the mixtures ranged from 7.5 to 11.5%, in increments of 2%. Autoclave treatment of the samples was carried out in an industrial autoclave at a pressure of 0.9 MPa with exposure for 8 hours. It is shown that the structure of lime sand concrete at the macro level consists of a continuous matrix of crystalline formations and discretely distributed sand particles and gaseous inclusions in the form of pores with a diameter of 10-(4–5) m, which are significantly larger in the composition with an activity of 7.5% of the raw material mixture. At the micro level, the structure is represented by individual consolidated morphological differences consisting of calcium hydrosilicates: tobermorite and α-C2S hydrate, as well as elements of their fusion and intergrowth, which are permeated by micropores with a radius of 10-(6–7) m.
18-23
Fine-grained concrete usage for borehole piles manufacture in case of geotechnical emergency
Abstract
Using the example of an unique case of emergency elimination in a deformed due to a landslide dam section, which was the base of the main urban pressure water supply pipelines, it is shown that the use of drilling piles made with electric discharge technology (EDT) prevented the soil embankment further destruction and ensured the pressure water pipe system safe operation. The technological cycle of manufacturing EDT drill-injection piles using discharge-pulse pile technology is presented. It is noted that the injected fine-grained concrete which is produced on the construction site just before it is injected into the well must be homogeneous and not delaminate during injection.
24-27
Eco-friendly and natural additives effect on building mixes strength at portland сement replacement
Abstract
A review of studies on Portland cement (PC) replacement in concrete is conducted in order to reduce negative impact on the environment. The factors such as the additives type and characteristics, hardening conditions (time, temperature), and mixture composition (water, Solid components, alkali, and binder proportion) influence on the concretes mechanical properties and microstructural characteristics is analyzed. It was found that the geopolymer binders (GPB) usage contributes to the denser and more homogeneous with fewer voids microstructure formation, what explains the increase in strength indicators. The key oxides (SiO2, Al2O3, CaO) content optimal ranges in the raw materials composition was determined. The main conclusion is the critical importance of the mixture and technological parameters composition optimizing for high mechanical properties achievement. Insufficient knowledge of the GPB structural elements behavior is noted, what determines the need for their operation under various loads research and development of the correct models establishing the relationship between compressive strength, bending, shear and elasticity modulus.
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Technology for producing foam concrete with predominantly closed porosity
Abstract
A brief analysis of the causes and stages of development of cellular concrete technologies has shown that the measure of gas porosity closure is one of the most important factors in determining their thermal efficiency and practical applicability. It has been noted that most types of layered building walls currently being constructed are prone to moisture accumulation during their operation, which can lead to negative sanitary and hygienic conditions inside the buildings and a decrease in their thermal efficiency. A comparison of the mass transfer features in two- and one-stage foam concrete mixtures during the homogenization stages revealed a list of reasons that contribute to an increase in the closed porosity in hardened foam concretes in the D400–D800 range. It has been experimentally established that the transition from a two-stage technology for producing foam concrete mixtures to a one-stage technology, by eliminating micelle formation at the stage of predominance of viscous bonds between the raw material components, reduces the volume of communicating pores in equal-density foam concretes by 12–40%. Dispersed reinforcement of such materials further reduces the communicating porosity by several times.
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Additive construction production: assessment of the technology economic efficiency in comparison with traditional construction methods
Abstract
The study results of the additive construction production technology (3D concrete construction printing) economic efficiency in comparison with traditional construction methods in low-rise individual housing construction (IHC) segment are presented. The research relevance is due to the need for an objective assessment of the innovative technology competitiveness amid systemic challenges in the industry – staff shortages and stagnation in labor productivity. Based on the questionnaire method and open source data, a unique sample of implemented pilot 3D printing projects from key participants in the Russian market was formed and analyzed. A comparative analysis with an extensive database of standard projects built according to the traditional technologies was performed. The article identifies and substantiates the current objective price range for additive construction facilities, identifies key factors affecting their cost, and ranks the technology relative to traditional analogues. It is established that in terms of unit cost, 3D printing in construction is already competing with the top quartile of projects implemented according to traditional technologies. The results obtained form an empirical basis for assessing investment attractiveness and scaling potential of additive technologies in the construction industry.
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Cement-free and unburnt binder and its activation method
Abstract
The article provides information on the development of a cement-free and unburnt binder based on glass waste and an alkali solution. These components are subjected to joint fine grinding in a ball mill. The resulting mass is highly thixotropic and easily liquefies under impact or vibration, while its adhesive properties are revealed. The glass-alkali adhesive mass hardens under heat treatment conditions (in the temperature range of 85–90оC) for 4–5 hours. During this process, the strength increases to more than 25 MPa. During the electrolysis process, the water of the mixture is activated, and its pH increases (increasing its alkalinity), which makes it possible to reduce the amount of alkaline component in the binder and increase its strength to 34 MPa. The binder can be used in the production of mortar and fine-grained concrete of medium grades instead of Portland cement.
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Prospects for the use of phase change materials as thermal insulation
Abstract
Modern requirements for building energy efficiency necessitate the use of materials capable not only of reducing heat losses but also of actively controlling thermal processes within building envelopes. Phase change materials are considered one of the most promising solutions due to their ability to store thermal energy through latent heat during phase transition. The aim of this paper is to analyze the types of phase change materials (PCMs), their physical operating principles, performance characteristics, and application features in the construction industry. The paper examines the main categories of PCMs, including paraffin-based materials, organic eutectics, hydrated salts, and composite systems, with a comparative assessment of their advantages and limitations. Global practices of PCM application in buildings of various purposes are reviewed, along with regulatory approaches adopted in Europe, the United States, China, and Russia. Particular attention is paid to current technological trends such as improvements in microencapsulation, stabilization of salt-based PCMs, and reduction of production costs. It is shown that phase change materials have significant potential for increasing the thermal inertia of buildings and reducing energy consumption; however, their widespread implementation requires further development of regulatory frameworks and technological solutions that take into account the specifics of local climatic conditions.
60-69
Recommendations for predicting the durability of asphalt concrete when using an inert gas environment
Abstract
Analyzing the main scientific papers and conference materials of oil industry experts on the problem of bitumen aging, it can be concluded that the basic cause of aging is the very fact of oxidation at the stage of bitumen production. New GOST standards and advanced laboratory control technologies are pushing for the introduction of new technologies, but in the Russian reality it is almost impossible to abandon oxidized bitumen, which is taken as the main starting point. If we objectively consider this issue, the aging factors that occur during the preparation of the asphalt concrete mixture play a much more significant role in the aging of bitumen than the problem of its oxidation during the production of a binder. There are many scientific papers, as well as various ways to solve this problem. Major scientists both in our country and abroad have been working on the issue of bitumen aging, but the problem is still relevant today.
70-75
Thermomechanical modeling of foam glass porous structure stabilization at annealing. Part 1. Mathematical models and computational methods review
Abstract
The analysis of annealing parameters effect on foam glass structural characteristics in order to purposefully control its properties is presented. The main attention is paid to the mathematical modeling of heat transfer processes and foam glass sample stress-strain state at the technological stage of annealing. The mathematical modeling methods for glass and foam glass annealing evolution is considered, various modeling approaches, including algebraic equations, integral and differential models, relaxation kinetic theory, numerical methods, and discrete modeling are analyzed. The study highlights that to understand the mechanisms of the heat transfer and the foam glass structure formation for production optimization is especially important.
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Development of domestic scientific research directions in the field of equipment for separation of particulate materials
Abstract
The article presents a comprehensive analysis of the development of domestic scientific research directions in the field of design and modernization of equipment for grinding and separation of particulate materials over the period 1989–2025. Based on a foresight analysis of doctoral dissertations in the field of mechanical equipment, systems, and technologies, research topics have been clustered, and the dynamics of scientific activity, its geographical distribution, and interdisciplinary connections have been assessed. Key trends have been identified: the predominance of studies focused on centrifugal separators and classifiers (accounting for approximately 40% of all works), a growing interest in mathematical modeling of aerodynamic processes (reaching up to 25% by the 2020s), and optimization of grinding plant operations. Particular emphasis is placed on the role of leading scientific schools and their contributions to advancing calculation methods, structural refinement of equipment, and the development of energy-efficient technologies.
90-104
Methods of functional nanomodification in the development and scientific submission of paint and varnish coatings for metal structures of bridge structures
Abstract
The paper presents the results of developing paint and varnish coatings for protecting metal bridge structures, featuring high durability under operating conditions. The focus is on preparing metal surfaces for painting, specifically developing a formulation for a pre-treatment composition prior to paint and varnish application. The composition is a solution based on mixed solvents, one of which is an ester and the other an aromatic hydrocarbon, containing nanomaterials. The specific solvents used in the composition, as well as the types and amounts of nanomaterials, depend on the type of film-forming agent in the applied paint and varnish. The conducted studies on a specific example of a composition formulation, including a solution based on mixed solvents (butyl acetate (52-55 wt.%) and toluene (45-48 wt.%), containing a concentrate with carbon nanotubes and silicon dioxide, in an amount of 0.01-0.2 wt.%, including 10 wt.% single-wall carbon nanotubes and silicon dioxide nanoparticles and 90 wt.% mixture of triethylene glycol dimethacrylate and alkylammonium salt of high-molecular copolymers showed that acrylic paint and varnish coatings acquire increased physical and mechanical properties (adhesive strength, abrasion resistance, resistance to deformation effects, etc.). At the same time, there is an increase in the dielectric constant of the coating (from 16.45 to 18.39), which characterizes its increased conductivity, as well as a decrease in the dielectric loss tangent (from 0.017 to 0.008), which indicates the production of antistatic coatings. The chemical resistance of the coatings increases, which characterizes their resistance to aggressive environments, expressed in better preservation of properties according to the criteria: change in gloss (hue), whitening, blistering, peeling, wrinkling. When considering the formation of interaction on the metal surface during its contact with the coating during surface treatment with nanomaterials, the following mechanisms of action of nanomaterials with a metal surface were revealed, which are consistent with the provisions of the electrical theory of adhesion and the theory of the physical chemistry of polymers: interaction of nanomaterials with surface atoms of the metal with the formation of electrovalent interaction by the donor-acceptor mechanism; Chemical interaction (chemisorption) of the active sites on the surface of carbon nanotubes with the metal surface layer. Industrial testing of the resulting solution yielded a positive result: after 28 months of operation, the coating obtained by surface treatment with the nanomaterial composition, compared to the untreated coating, performs its functions and exhibits superior decorative and protective properties. The technical and economic efficiency of the developed approach is ensured by improved adhesive-cohesive interaction of paint and varnish coatings, which creates conditions for extending their service life and periods between repairs; and by reducing resource and energy costs without compromising coating quality due to the use of a small amount of binary nanomaterials in the developed composition.
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