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Comparison of technological properties of clay raw materials during the tests using plastic and soft methods of brick molding

https://doi.org/10.58224/2618-7183-2026-9-2-7
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Abstract
The article presents the results of studies of technological properties of clay raw materials using the example of highly dispersed refractory clays of Vladimirovskoye deposit and low-dispersed fusible loams of Aksayskoye deposit in relation to plastic and soft methods of product molding. Research in this area is being conducted due to the lack of testing methods for clay raw materials in relation to the wet method of product molding, despite the fact that ceramic bricks produced using this production technology are in high demand in modern construction and architecture. In Russia, only a few companies produce bricks using this technology, and many companies have not yet been able to master this technology. Comparative tests on typical water-soaked clay raw materials showed that the existing accepted methods approved by regulatory documents cannot be applied to soft molding technology and that a separate method needs to be developed. Thus, with soft molding, molding materials are characterized by an increased degree of deformation under load, reduced plastic strength and critical compressive stress, as well as increased stickiness. It has been shown that a simple increase in the moisture content of molding materials leads to the deterioration in the basic pre-firing technological properties: air shrinkage, sensitivity to drying, cohesion; and to achieve the required degree of sintering, an increased firing temperature is required. Therefore, increasing the moisture content of molding materials is not a simple solution. Molding materials for soft molding must contain increased amounts of leaners with grain compositions approaching the densest packing and the presence of the required amount of sand fraction particles. Otherwise, obtaining high-quality facing ceramic bricks with high decorative properties becomes extremely problematic from a technological perspective. The results of the conducted research will allow to move closer to the development of a method for selecting raw materials for soft molding of ceramic bricks and, in practical terms, will help in organizing production using this technology.
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The effectiveness of internal hydrophobization of concrete in biologically aggressive environments

https://doi.org/10.58224/2618-7183-2026-9-2-8
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The article is devoted to the effect of internal hydrophobization of concrete cement stone on the kinetics of damage by Aspergillus niger fungi. The studies were carried out on samples made of ordinary Portland cement with a W/C = 0,3. As a hydrophobic agent, 0,5 and 1% by weight of cement of calcium stearate were introduced into the cement mixture. The kinetics of calcium leaching from cement stone was evaluated by changes in the calcium content in the liquid when samples were exposed to water. Internal hydrophobization of cement stone with calcium stearate makes it possible to reduce the removal of calcium from the solid phase by 2,5-3 times, even with biofouling of the surface. The equilibrium state in the «cement stone – water» system occurs 70 days after the samples are immersed in a liquid medium. The profiles of calcium concentrations along the thickness of the cement stone characterize a decrease in mass transfer in samples with hydrophobic additives. The introduction of calcium stearate into the cement mixture increases the total calcium content in the structure and reduces calcium leaching as a result of liquid and fungal corrosion. Volumetric hydrophobization of cement stone leads to a decrease in the values of mass conductivity coefficients by two orders of magnitude, from 10-9 to 10-11 m2/s. Using a mathematical model of concrete biocorrosion, the degree of destruction under the influence of fungal microorganisms and water is predicted after 15 years. During this period, corrosion processes will occur in ordinary concrete throughout its entire thickness, in hydrophobic concrete – only in the surface layer. With calcium stearate additives to concrete, it is possible to extend the maintenance-free service life under conditions of exposure to fungi and moisture for up to 30 years.
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Impact of aircraft landing load on the crack resistance of hybrid basalt fibre-reinforced aerodrome concrete pavements

https://doi.org/10.58224/2618-7183-2026-9-2-9
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Abstract
Hybrid basalt fibre-reinforced concrete (HBFRC) has emerged as a high-performance material capable of addressing the severe mechanical demands placed on aerodrome pavement systems. By integrating basalt micro and macro fibres, the composite gains improved stiffness, enhanced crack-arrest capacity, and greater resistance to repeated aircraft-induced loads. This study develops and analyses 25 hybrid concrete mixes using both laboratory testing and a detailed finite element simulation in Ansys Workbench to quantify how different fibre proportions influence compressive strength, stiffness, and deformation under an Airbus A321neo load. A 3D fracture-based pavement model incorporating predefined semi-elliptical crack geometry was used to evaluate the de-formation response across 7-, 14-, and 28-day curing periods. Results show a clear improvement in mechanical performance with hybridisation, with the mix containing 2% basalt microfibres and 1% macrofibres consistently yielding the lowest deformation values (0.0054353mm, 0.005815mm and 0.0057363mm) for 7 days, 14days and 28 days respectively, indicating superior crack-resistance and load-bearing capacity throughout the curing stages. While the mix containing 0.5% basalt microfibres and 0.5% macrofibres yielded the highest deformation values (0.0059277mm and 0.0058474mm) for 14 and 28 days respectively. The findings demonstrate that optimal hybrid fibre combinations significantly reduce pavement vulnerability to its risk of being susceptible to damage from changing aircraft loads like heaving traffic and can serve as practical reinforcement strategies for strengthening modern airfield infrastructure. The study further highlights the importance of micro–macro fibre synergy in improving fracture behaviour and offers valuable guidance for developing next-generation high-durability airport pavement materials.
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Peculiarities of perception of the urban environment in the system of a modern metropolis (on the example of children’s autonomy in an urban environment)

https://doi.org/10.58224/2618-7183-2026-9-2-10
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This article explores how preschool children perceive the urban environment and how urban space influences the development of their autonomy. Drawing on interdisciplinary perspectives from urban planning, environmental psychology, and child development, the study analyzes the ways young children interact with and interpret their everyday urban surroundings. A mixed-methods research design was employed, combining qualitative and quantitative approaches, including semi-structured interviews, children’s drawings, and content and cluster analyses. The empirical study was conducted with a sample of 130 preschool children aged 4-6 years living in the central districts of Baku. The findings demonstrate that children’s urban experiences are largely shaped by interactions with parents and close relatives, while environmental awareness is strongly influenced by intergenerational factors, particularly the role of grandparents. Limited opportunities for independent interaction with urban objects and spaces lead many children to compensate through imaginative constructions of an idealized, fairy-tale city. Children’s perceptions reveal early sensitivities to environmental problems, social behavior in public spaces, and the availability of safe and accessible areas for play and communication. The results highlight that children’s views of the city serve as an important indicator of how urban environments support or constrain cognitive, emotional, and social development. The study emphasizes the necessity of incorporating children’s perspectives into urban planning and social policy, offering practical implications for the design of inclusive, child-friendly, and sustainable urban environments.
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Assessment of seismic response of a 29-storey building on raft and piled raft foundations considering soil–structure interaction

https://doi.org/10.58224/2618-7183-2026-9-1-1
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This paper presents a comparative analysis of the performance of raft and piled raft foundations using the case study of a 29-storey building designed for the seismically hazardous area of Grozny. The investigation is based on numerical modelling of the interaction within the “structure–foundation–multilayered soil” system taking into account the actual geotechnical conditions and dynamic properties of soil. Seismic loading is considered as a stationary random process. The analysis investigates the distribution of resonant frequencies of the system, the spectral density of the random acceleration function of the system, and its dynamic amplification factor. Frequency characteristics of the building were obtained using the LIRA-SOFT software package. The evaluation of the dynamic amplification factor was carried out by solving a stochastic problem of wave propagation in a multilayered medium.
The results demonstrate that the piled raft foundation reduces the dynamic response of the building. Despite its higher cost, the use of such a foundation is justified in the conditions of increased seismic hazard and weak soils. The obtained findings allow us to recommend a piled raft foundation as the preferred structural solution for high-rise buildings under engineering-geological and seismic conditions similar to those of Grozny.
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Prediction of concrete nonlinear creep using machine learning methods

https://doi.org/10.58224/2618-7183-2026-9-1-2
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Abstract
Based on the experimental data of concrete nonlinear creep under high stress levels (40-80% of prismatic strength), this study explores the application of machine learning methods for predicting creep deformation. A recurrent artificial neural network (ANN) and the CatBoost algorithm were employed to model the time-dependent creep strain, using stress and time as input parameters. The ANN demonstrated high predictive accuracy, with training achieving a mean square error of 0.000154, and its generated creep curves showed an excellent fit with the experimental data. In contrast, the CatBoost algorithm, while effectively capturing the physical trend that creep strain increases nonlinearly with stress and decelerates over time, exhibited lower prediction accuracy than the ANN. Feature importance analysis within the CatBoost model highlighted the significant influence of lagged stress parameters and time-squared terms, aligning with the nonlinear physical nature of concrete creep. The results confirm the strong potential of machine learning, particularly recurrent neural networks, for modeling complex nonlinear creep in concrete, even with limited datasets. Future work is suggested to incorporate concrete strength class and loading age as additional parameters to enhance model generalizability.
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Salt spray corrosion test, hardness test, and abrasion test of nanomodified phosphate coatings

https://doi.org/10.58224/2618-7183-2026-9-1-3
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Abstract
The development of new rust converter formulations is a relevant issue that contributes to increasing the competitive edge of domestic products and sustainable development of various branches of the economy. The aim of the study is to determine the corrosion resistance of various phosphate films on the metal surface when exposed to salt spray, as well as to determine hardness and resistance to abrasion (scratching).
Materials and methods: Metal rods are coated with a film using a special surface treatment with orthophosphoricacid-based rust converters. The study introduces a new experimental rust converter formulation containing a Lewis acid (or its salts) and dispersed nanopowders of oxide and other inorganic/organic complexes.
Results: Tests revealed that full-scale corrosion of metal rods treated with the experimental formulations began after 9 and 10 days, while untreated rods were showing signs of corrosion as early as on the second day. These films also demonstrated a hardness of 490 HV (modified scale of a TEMP-4 hardness tester) and withstood a maximum indenter load of 4.1 kg (measured with PROMTPP-1518) based on ISO 1518 method (scratching with a needle).
Conclusions: Based on the test results, it was concluded that the modified phosphate films exhibit high hardness and resistance to needle scratching according to ISO 1518 method, and also exhibit increased corrosion resistance to salt spray. However, the demonstrated resistance is insufficient for exposure to a salt spray chamber for 42 days.
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Effect of curing regimes on phase composition and compressive strength of geopolymer binders based on ash and slag waste from thermal power plant

https://doi.org/10.58224/2618-7183-2026-9-1-4
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This study focuses on the investigation of compressive strength of geopolymer binders based on alkali-activated ash and slag waste from thermal power plant. It has been found that the significant factors affecting the mechanical strengths are the reactivity of the precursor and curing regimes of geopolymer binders. First of all, the quantity and the structural characteristics of amorphous phases in these materials play a crucial role in determining the mechanical performance. According to the X-ray data, both fly ash and slag as well as the geopolymers based on these precursors, demonstrate the presence of an amorphous hump. The quantity of amorphous phase in slag component (70.4%) is higher than in fly ash one (63.9%). Besides, compared to the original slag, the radius of the first coordination shell for the “low-angle” amorphous phase R1 = 7.3 Å is higher than that of the fly ash R1 = 7.0 Å. This indicates that the slag component demonstrates the presence of regions of increased free volume. On the other hand, the proportion of the crystalline phase in the original slag is 29.6% in comparison with fly ash (36.1%) and is represented primarily by silicon oxide along with minor amount of hematite and magnetite. It has been determined that a sharp decrease in the crystalline phase content with increasing the heating medium temperature and pressure for slag-based geopolymers is observed. The geopolymer obtained by autoclave curing contains only 1.8% crystalline inclusions. DTG analysis indicates that the peaks corresponding to the geopolymers cured under autoclave regimes (both based on fly ash and slag components) are deeper and broader in comparison with binders cured under elevated temperature and atmospheric pressure. The compressive strength of slag-based geopolymer samples is much higher than of ash-based ones regardless of the curing regime. This is due to the properties of slag component: improved reactivity – the higher proportion of amorphous phase and aluminum oxide, lower water demand – the proportion of loss on ignition is practically negligible.
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Influence of heat resistance of the enclosing structures of a heated room on the choice of the type and location of the heating device

https://doi.org/10.58224/2618-7183-2026-9-1-5
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The article examines the influence of heat resistance of enclosing structures on the choice of type and location of heating devices in the room. The main attention is paid to the relationship between the thermal characteristics of fences and the method of heat transfer of heating devices. The paper considers two main types of heat transfer: convective and radiative. It is shown that at low thermal stability of structures, it is advisable to use devices with a predominant convective heat transfer (convectors, panel radiators), and at high – with radiation (radiators, underfloor heating, infrared heaters). A mathematical model of spatial non-stationary heat transfer in a heated room is developed, taking into account various thermophysical characteristics of enclosing structures and the type of heat release sources. The study of the amplitude of fluctuations in the temperature of air and internal surfaces, depending on the type of heating device, is carried out. The practical significance of the work is the development of scientifically based recommendations for the selection and placement of heating devices, taking into account the heat resistance of enclosing structures. The results of laboratory tests confirm the theoretical conclusions and demonstrate the nature of the temperature distribution in the room under various heat exchange conditions. The results of the study show that the correct choice of the type and location of the heating device allows you to ensure uniform heating of the room, minimize energy consumption for heating and create comfortable microclimate conditions.
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Features of using national symbols, geometric forms, decorative elements, and color schemes to reflect state identity in the architectural composition of diplomatic missions

https://doi.org/10.58224/2618-7183-2026-9-1-6
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The visual identification of diplomatic missions has gained particular importance in the context of globalization and intercultural interaction. Embassy architecture represents functional structures and a powerful means of expressing national identity. However, professional practice still lacks a consistent system of criteria for selecting architectural and symbolic elements that reflect the unique characteristics of the sending state. The focus of this study is on identifying architectural approaches to integrating national symbolism into the design of modern embassies.
The methodological foundation of this study is a qualitative and quantitative approach that includes the selection of case studies, comparative architectural analysis, and expert surveys. The research identifies stable categories of symbolism: official (flag, coat of arms) and secondary (historical style, color schemes, geography). An analysis of diplomatic missions in various countries has revealed that architects typically employ three main strategies: the use of dominant structural forms, the incorporation of traditional decorative elements, and the symbolic integration into the local context.
The results confirm the importance of national color schemes and geographical metaphors in creating a recognizable image. The conclusions emphasize the need to find a balance between national identity and contextual appropriateness, as well as respect for the architectural traditions of the host country. The study highlights the architectural tools of soft power and proposes a systematic approach to designing diplomatic missions as spaces for representing statehood.
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