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Eco-Friendly Foam Concrete with Improved Physical and Mechanical Properties, Modified with Fly Ash and Reinforced with Coconut Fibers

https://doi.org/10.58224/2618-7183-2025-8-1-1
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Аннотация
The development of new types of environmentally friendly and cost-effective building materials is currently a relevant topic and is actively developing throughout the world. In modern construction materials science, the most popular direction is the development of new concrete compositions using waste of various origins. The objective of this study is to develop new compositions of foam concrete using local waste from the fuel and energy complex and plant natural fibers. To determine the optimal amount of the modifying additive fly ash (FA), 7 experimental concrete compositions with different percentages of cement replacement by FA were made. The content was established as optimal. Foam concrete with 15% FA has the lowest density of 1075 kg/m3 and a minimum thermal conductivity coefficient of 0.248 W/m × °C, as well as increases in compressive and bending strength of 23.3% and 21.7%, respectively. The effect of coconut fiber (CF) was assessed on the composition of foam concrete modified with the optimal amount of FA 15%. The optimal dosage of CF was 0.6%. As a result of FA modification and CF dispersed reinforcement, a complex effect was obtained. The increase in compressive and bending strength was 30.14% and 72.83%, respectively, compared to conventional foam concrete. The density and thermal conductivity coefficient decreased by 9.8% and 8.34%, respectively. The results obtained during the experimental studies prove the effectiveness of the proposed formulation solutions and allow obtaining an energy-efficient foam concrete composite with improved characteristics.
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Photocatalysts based on Zn-Ti layered double hydroxide and its calcination products for self-cleaning concretes: Structure formation and photocatalytic activity

https://doi.org/10.58224/2618-7183-2025-8-1-2
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Аннотация
Currently, the development of highly active photocatalytic additives for self-cleaning cement materials is a topical direction of building materials science. Mixed transition metal oxides are one of the effective types of photocatalysts, because they have improved functional characteristics compared to monometallic compounds. The purpose of this study was to establish the effects of synthesis conditions on the structure parameters and photocatalytic activity of zinc-titanium layered double hydroxide (Zn-Ti LDH) with Zn2+/Ti4+ molar ratio of 2/1, as well as its calcination products in the form of zinc-titanium mixed metal oxides (Zn-Ti MMOs). It was found that the mixing temperature of solutions of precursor salts and precipitators, as well as the temperature of sediment aging, were the main synthesis parameters that had the greatest impact on the phase composition and crystallite size of layered double hydroxide.
The research results showed differences in the kinetics of photodestruction of methylene blue (MB) in solution under UV radiation in the presence of Zn-Ti layered double hydroxide and Zn-Ti mixed metal oxides. The photocatalytic process involving Zn-Ti MMOs, corresponding to a pseudo-first order reaction kinetic, proceeded in a diffusion mode with limiting step in the form of dye adsorption on the surface of photocatalyst. The photodegradation of MB in the presence of Zn-Ti LDH, which was more accurately described by a pseudo-second order model, occurred in a kinetic regime, where the photocatalytic reaction was the limiting stage.
Mixed metal oxides of zinc and titanium had significantly higher functional characteristics compared to their Zn-Ti LDH precursor. The calcination of Zn-Ti layered double hydroxide at 200–500 °C allowed to achieve the highest photocatalytic activity of Zn-Ti MMO, which was due to phase transformations occurring during thermal treatment. The decomposition of Zn-Ti LDH at 200–250 °C resulted in the formation of a crystalline phase of zinc oxide (ZnO), which had a hexagonal wurtzite crystal structure with the ability to effectively absorb radiation from almost the entire UV spectral region. The rise of the Zn-Ti LDH calcination temperature to 500 °C led to an increase in the crystallinity degree of ZnO.
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Heat dissipation of cement and design the composition of concrete for massive structures

https://doi.org/10.58224/2618-7183-2025-8-1-3
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Аннотация
Introduction. When designing a concrete composition depending on the type of structure, cement content is determined taking into account regulatory requirements for the minimum cement content depending on the operating environment. The maximum cement content is limited by economic indicators and technical conditions depending on the methods and conditions of work; the limitation on the amount of heat dissipation is not considered. Research objective: to develop a methodology for accounting for the heat dissipation of cement when assigning its consumption in concrete compositions for massive structures depending on their parameters and construction conditions. Methods. Experimental studies and analysis of regulatory documents and literary data on heat dissipation of cements and concretes. Modeling the parameters of temperature fields and stress fields depending on the class of concrete and its specific heat dissipation using the example of a foundation slab with specified dimensions and parameters of heat exchange with the environment. Results: An approach is proposed to standardizing the value of the maximum heat dissipation of concrete when designing a concrete composition for massive reinforced concrete structures. The article substantiates the position that the value of the level of tensile temperature stresses is less significantly affected by the concrete class than by its specific heat dissipation, since it is the heat dissipation of concrete that forms the temperature field and the temperature difference "center – top". Prevention of the risk of early cracking is associated not with slowing down heat dissipation, but with the value of specific heat dissipation, which determines the parameters of temperature fields, temperature gradients and stresses. The example shows that for a massive flat foundation slab with an accepted permissible level of tensile stresses of 0.67, the value of specific heat dissipation of concrete should not exceed 140 mJ / m3. A principle is proposed for determining the maximum class of concrete for compressive strength depending on the properties of cement. A dependence between the level of tensile temperature-shrinkage stresses and the criterion of thermal crack resistance of Zaporozhets I.D., independent of the concrete class, is revealed.
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Investigation of structure and properties of expanded clay waste with the purpose of their use in the construction industry

https://doi.org/10.58224/2618-7183-2025-8-1-4
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Аннотация
This paper describes the structure and properties of large-tonnage expanded clay gravel waste, which is generated as dust from the cyclone, or clay dust (when drying granules), and expanded clay dust from filters (when leaving the kiln, from the cooler and screen). The mineralogical and phase composition of expanded clay dust and its hydraulic activity were determined. Clay dust from cyclones corresponds to the specific surface of 2500 cm2/g, and expanded clay dust from filters - 6800 cm2/g, which allows us to recommend it for use as a fine mineral additive to cement mortars and concretes. Due to the fact that the bulk density of clay dust is about 1000 kg/m3, and expanded clay dust - 6300 kg/m3, it allows to recommend it in the form of facilitating raw material additives in the production of wall and partition products. The results of X-ray phase analysis of clay dust from cyclones showed the presence of significant residues of unburnt clay (more than 80%), and the analysis of expanded clay dust from filters showed the presence of solid high-temperature phases consisting of: Quartz (SiO2) – 50.28%, Albite C-1 (NaAlSi3O8) – 14.82%, Microcline maximum (KAlSi3O8) – 15.73%, Lime (CaO) – 2.77%, Calcite (CaCO3) – 5.11%, Alunogen (Al2(SO4)2(H2O)22) – 11.29%. Hydraulic activity of clay and expanded clay dust according to the methods of GOST R 56593 and GOST 30744 showed that it is extremely low, especially for clay dust (0.3 MPa). On the contrary, the characteristics of samples of clay-alkali compositions showed sufficient strength (for clay dust up to 6.8 MPa, and expanded clay dust up to 3.6 MPa), which allows them to be recommended as a component of slag-alkali binder for cement-soil bases of highways.
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The effect of the temperature difference in the thickness of three-layer reinforced concrete enclosing structures in the operational stage on their stress-strain state

https://doi.org/10.58224/2618-7183-2025-8-1-5
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Аннотация
In three-layer reinforced concrete structures, the inner and outer layers of concrete of different physical and mechanical characteristics have different coefficients of thermal conductivity and linear temperature deformation. During the operation of buildings and structures, due to the temperature difference in the thickness of the structure along the contact planes of the layers, shear stresses may occur, which leads to bending of the structure, an increase in its deflections and a decrease in crack resistance. In this regard, when designing and calculating such structures, it is necessary to take into account the operational stresses and deflections caused by the temperature difference in the thickness of the enclosing structure.
Taking into account the fact that the cross-section of three-layer enclosing structures with a monolithic connection of layers includes various types of concrete and reinforcement, differing in the values of the initial modulus of elasticity, to solve the problem, the cross-section of the enclosing structure is reduced to a homogeneous one corresponding to the largest initial modulus of elasticity of the concrete of the outer layers.
Studies have been carried out to identify the effect of the thickness of the enclosing structure on the change in deflection, depending on the temperature difference, and its share in the total deflection of the structure. Despite the fact that the calculation results revealed a slight increase in the total deflection, taking into account the proportion of deflection that depends on the temperature difference, the study allows us to increase the accuracy of the calculation. The tendency to reduce the material consumption of structures and, consequently, a decrease in the thickness of the structure can lead to an increase in the proportion of deflection, depending on the temperature difference, which must be taken into account when choosing design solutions.
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Predicting the risk of early cracking in massive monolithic foundation slabs using artificial intelligence algorithms

https://doi.org/10.58224/2618-7183-2025-8-1-6
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Аннотация
The article presents a study of the application of artificial intelligence algorithms in predicting the risk of early cracking in massive reinforced concrete structures using monolithic foundation slabs as an example. The current experience of using algorithms such as convolutional neural networks, deep learning tools (YOLOv5 model) for crack detection at various stages of the life cycle of massive reinforced concrete structures is analyzed. The causes of crack formation, physical and mechanical processes, including cement hydration are considered.
A model has been developed that predicts the magnitude of the tensile stress level in monolithic foundation slabs during construction, based on CatBoost using Python, allowing to predict the risks of early cracking with an accuracy of up to 98%.
The model was trained on synthetic data containing various design parameters and material properties, including the geometric dimensions of the slabs, the temperature on the upper surface, the heat transfer coefficient on the upper surface, the curing rate, the class of concrete and the characteristics of the soil base. Statistical analysis of the data was performed, a correlation matrix was constructed. Practical and predicted values of the model were visualized in the form of a scatter plot. The most significant parameters influencing the risk of early cracking in massive monolithic foundation slabs were obtained. The constructed model passed quality assessment according to three metrics: MAE=0.0011; MSE=4.038; MAPE=0.0014.
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The effect of the aerodynamics of indoor air flows on the power of the heating system

https://doi.org/10.58224/2618-7183-2025-8-1-7
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Аннотация
An analytical dependence is presented for calculating the power of a heating system, taking into account the aerodynamics of the movement of air flows inside a heated room. The analytical dependence is derived on the basis of the theory of a two-zone mathematical model of a heated room. The method allows us to determine a rational way of organizing heating to ensure minimal transmission heat loss through enclosing structures, taking into account factors affecting thermal and air processes in a heated room and contributing to a decrease in the power of the heating system as a whole. The results of the analysis carried out on the regularity of the movement of air flows in a room divided into two control volumes (CV): upper and lower CV. A mathematical model of the processes of heat and mass transfer of a heated room in an administrative or residential building has been developed, which takes into account the heat exchange between the upper and lower CV. The physical picture of the distribution of air and heat flows in a heated room with a local heat source located in the window sill space of the heated room is analyzed. A method for calculating the power of the heating system is proposed, taking into account the nature of the aerodynamics of the distribution of air flows in a heated room. An analytical dependence for calculating the thermal power of a heating system is presented, taking into account the characteristics of the distribution of heat and air flows across two control volumes of the heated room.
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Factors of territorial resource use in the reconstruction of multi-purpose healthcare facilities

https://doi.org/10.58224/2618-7183-2025-8-1-8
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Аннотация
Medicine is one of the most important directions for the country development and has a fundamental position in the socio-economic policy of the state, ensuring the human health and well-being. With the development of medical technologies, the standards of medical care are also growing, and the requirements to healthcare facilities are becoming more stringent. In the conditions of dense urban development, the construction of a multi-purpose medical center that fully meets the standards may be problematic, and therefore the possibility of reconstruction of existing healthcare facilities to meet up-to-date requirements is being considered. The purpose of this article is to determine the possibility of reconstruction of multi-purpose healthcare facilities through densification of development; to analyze the methods of densification in relation to the territories of multi-purpose healthcare facilities; and to detect the architectural principles in the densification of development of multi-purpose healthcare facilities. The article authors also show the architectural techniques used in reconstruction with an increase in the technical and economic indices of the facility. The methodology of this research represents the analysis of academic papers, as well as the analysis and generalization of practical experience in the architectural design and reconstruction of multi-purpose healthcare facilities, including the personal experience of the article authors. The result of the research is the determination of the basic principles of the reconstruction of multi-purpose healthcare facilities, which make it possible to create the up-to-date typology of a healthcare facility, and have an impact on the formation of the architecture of multi-purpose healthcare facilities. The research is aimed at forming the up-to-date typology and architecture of multi-purpose healthcare facilities during reconstruction.
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Methods for assessing the quality of architectural spaces of educational institutions

https://doi.org/10.58224/2618-7183-2025-8-1-9
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Аннотация
School plays a key role in the development of a person's personality throughout their life. The educational atmosphere largely shapes behavior patterns, especially for children and adolescents. The foundations laid at an early age often become decisive for the further development of the personality. Today, approaches to the educational process have undergone significant changes. The article presents a methodology developed by the authors that allows assessing the quality of architectural spaces of educational institutions by four main parameters. This will allow obtaining an objective picture of the state of educational spaces and making adequate architectural and design decisions at the administrative level. This work is based on an integrated approach to assessing architectural space, developing universal assessment models that allow correlating different-quality characteristics of school subsystems into a single assessment system, which will allow obtaining a quantitative assessment of the state of spatial indicators of educational institutions. Methods for assessing architectural spaces of educational institutions suggest entering a new stage of designing specific schools, eliminating serious consequences of architectural and design errors with large budget losses when implementing poor-quality development scenarios. The priority task of reforming the system of public authority is to create a qualitatively new level of public administration efficiency, including in matters of spatial development of educational institutions and renovation of existing schools. Because of the study, the main criteria and indicators of the quality of the architectural educational space were developed. The matrix of criteria includes such evaluation blocks as safe environmental design; formation of space; inclusiveness; stages of the physical condition of the building. The evaluation criteria were tested and refined in schools of the Republic of Bashkortostan. The results of the project implementation are methodological tools for assessing the quality of architectural spaces of educational institutions, an application for assessing the initial level of quality of architectural space, modeling the architectural planning solution of an educational institution and estimate documentation at the stage of an application for major repairs.
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Principles of the organization of space-planning solutions for nuclear medicine facilities

https://doi.org/10.58224/2618-7183-2025-8-1-10
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Аннотация
It is nearly impossible to imagine modern medicine without the use of nuclear technologies, the introduction of which has led to the emergence of new methods of prevention, diagnosis and treatment of various diseases, as well as reduced mortality rates among patients and improved the quality of life of patients with diseases in the field of oncology, cardiology, neurology and others. The purpose of this article is to systematize the principles of the organization of architectural space-planning solutions based on the studied experience of the constructed nuclear medicine facilities. The methodology of this research constitutes an analysis of statistical data and academic papers, in which the authors examine the core process equipment used at nuclear medicine facilities, the main architectural typological zones of nuclear medicine facilities, and highlight the requirements to the premises in which the source of ionizing radiation is located. In addition to the analysis of academic papers, the methodology of this research includes the analysis of practical experience in the architectural design and construction of nuclear medicine facilities, as a result of which the authors analyzed space-planning and architectural solutions used in the design and construction of nuclear medicine facilities. As part of this article, the authors present, in particular, an analysis of the experience of personal design of a number of Russian nuclear medicine facilities. Furthermore, special attention in the article is paid to the principles of architectural and planning solutions for children’s medical institutions (in particular, with oncological specialization). The result of the research is to build up a sketch model of the space-planning solution of the nuclear medicine facility as a multi-purpose facility, to determine the principles that affect the formation of space-planning solutions. The research is aimed at forming a space-planning solution for a multi-purpose nuclear medicine facility, taking into account the possibility of increasing its capacity during operation.
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