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Technical solutions and technologies for energy-efficient overhaul of apartment buildings

https://doi.org/10.58224/2618-7183-2025-8-3-4
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Abstract
The study presents a comparative analysis of technical solutions and technologies for energy-efficient capital repairs of apartment buildings. The purpose of the study is to determine the most effective ways to increase the energy efficiency of a residential building by carrying out repair work. The methodological approaches of the study are based on a statistical analysis of the data on the results of major repairs in the practice of world construction. According to the results of the study, it was found that when planning major repairs in order to reduce energy consumption, special attention should be paid to choosing a set of technical solutions that collectively contribute to improving the energy efficiency of a residential building. The analysis showed that with the introduction of modern energy-saving technologies, the overhaul of apartment buildings makes it possible to modernize each building, increasing its level of energy efficiency and prolong its service life for at least a quarter of a century, which as a result improves the quality of life of citizens and accelerates the economic growth of the country. In our opinion, taking into account the international experience of reducing heat losses and energy consumption in residential apartment buildings, it is necessary to adopt new rules establishing approaches to determining the energy efficiency class and appropriate labeling of construction products, with a transition from using a relative indicator (deviations of the actual or projected annual specific energy consumption from the normative value) to setting minimum and maximum values (ranges of values) of energy consumption in apartment buildings for each energy efficiency class.
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Investigation properties of microsilica to assess the possibility of its use as an additive in concrete production

https://doi.org/10.58224/2618-7183-2025-8-3-5
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Abstract
A comprehensive study of the composition, structure and properties of microsilica from the sludge field of JSC Kremniy was conducted. It was shown that the capture of microsilica during gas purification with a soda solution and its storage under a layer of water on the sludge field for many years contributed to the formation of agglomerates of particles with an average size of 7-16 μm, consisting of nanosized amorphous silica particles of spherical shape. It was found that microsilica has a relatively low pozzolanic activity, and agglomerates of its particles formed during capture during gas purification and long-term storage on the sludge field reduce the efficiency of using microsilica as an active mineral additive. To increase the activity of microsilica and destroy agglomerates, intensive mechanical action is required during the processing of microsilica as part of various building materials. The laboratory studies have confirmed the possibility of using microsilica in the construction industry as an active mineral additive to cements, including as a substitute for part of the clinker, as an "acidic" component of unfired hydraulic and autoclave hardening binder, and as a silica-containing additive to raw sludge for clinker firing. It has been shown that the use of microsilica from JSC "Kremniy" in the construction industry will improve the environmental situation in the region, and the experience of using waste described in the work can be extended to other metallurgical enterprises.
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Ferrocene-containing compounds as combustion catalysts and solid fuel modifiers

https://doi.org/10.58224/2618-7183-2025-8-3-6
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Abstract
Low pressure profile and stable burning rate are important and necessary characteristics of high-quality solid fuels. Achieving their optimal values is accomplished by incorporating combustion catalysts. There are several types of combustion catalysts, such as metal nanoparticles, oxides, transition metal chelates, and catalytic mixtures based on them. Among catalysts, ferrocene and its compounds hold a special place. They are widely used in the aerospace industry due to their superior microscopic homogeneity, proper ignitability of rocket fuel, and compatibility with organic binders. However, ferrocene compounds tend to migrate within the composite, leading to matrix degradation, reduced storage life, and shorter operational lifespan of the fuels. Polymeric ferrocene catalysts represent a new generation of catalysts that retain activity while exhibiting reduced migration tendencies. They have a polymeric structure in which the ferrocene group can be placed in the main or side chain.
In this study, in addition to reviewing current knowledge on polymeric ferrocene combustion catalysts, synthesis methods and their application results were examined, as well as their migration in fuels compared to other catalysts. The conducted research demonstrated that polymeric ferrocene catalysts are synthesized through free-radical and graft polymerization, resulting in dendrimer-like polymers. Furthermore, the use of a hyperbranched polymeric ferrocene catalyst, compared to a ferrocene catalyst bound to a small molecular group, simultaneously reduced the migration rate by 90%. The iron content in the catalyst, the polymer's molecular weight, the placement of ferrocene in the polymer structure, and the degree of linearity of the polymeric structure are among the most important factors influencing the efficiency of these catalysts.
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Study of thermal-physical properties of porous ceramic insulation products

https://doi.org/10.58224/2618-7183-2025-8-3-7
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Abstract
The detailed description of the main parameters, influencing the thermal insulation characteristics of building walls is presented in this article. In addition the analysis of this parameters study in modern construction practice is made. The main characteristics of concrete based on porous expanded clay granules are presented, including the results of studies of capillary absorption, moisture transfer rate and moisture absorption properties of porous expanded clay concrete samples affecting the thermal conductivity coefficient. The research results are presented in the context of thermal insulation and fire-resistant ceramic granules application as fillers in porous concrete walls. On the basis of results of study of the organomineral additives influence on the thermal conductivity coefficient of porous expanded clay concrete the study of porous expanded clay concrete samples were carried out. The porous and dense wall concrete sorption moisture and vapour permeability are determined in laboratory conditions. Also the main changes of these parameters at different values of relative humidity of surrounding air are determined.
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Influence of the nature of curing agents, modifiers, and fillers on the functional characteristics of epoxy polymers

https://doi.org/10.58224/2618-7183-2025-8-3-8
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Abstract
This article investigates the influence of the components of epoxy systems – curing agents, modifiers, and fillers – on the properties of epoxy resins, including the formation of materials exhibiting an electret state. The study examines three key aspects of epoxy composite formation: the type of curing agent, modifying additives, and fillers, as well as their impact on the structure and characteristics of the final material. It is demonstrated that curing agents determine the basic structure of the epoxy network, and the correct selection of a curing agent is essential to achieve the desired combination of mechanical and dielectric properties. By varying the type of curing agent and the curing conditions, it is possible to alter the gel fraction content. The uncrosslinked portion of the epoxy polymer can enable the orientation of dipolar groups or macromolecular segments under the influence of an external electric field, thereby inducing material polarization and yielding a chemoelectret with high electret performance. A high gel fraction content ensures the retention of the polarized state over extended storage (service) periods of the chemoelectret. Modifiers of the epoxy matrix serve for fine-tuning the properties. Increasing the modifier content in the composition alters the number of functional groups capable of polarization, which in turn affects their electret properties. Fillers are used to enhance the mechanical and functional (including electret) characteristics of epoxy compositions. It is shown that, for the creation of chemoelectrets capable of long-term charge retention, non-conductive fillers that do not form conductive pathways are preferable. Such fillers may act as charge traps while simultaneously increasing the strength of the polymer. To ensure long-term retention of the electret state, composite systems with minimal conductivity should be developed to prevent rapid charge dissipation. It may be assumed that, when creating an epoxy composite with a curing agent and a conductive filler (up to 5 vol.%), the dispersed particles act as sources of additional injected charge carriers, functioning even after the removal of the external electric field. It is concluded that the combination of epoxy resin with various curing agents, modifiers, and fillers enables the production of materials with tailored parameters. These materials can simultaneously serve as load-bearing structures and protective coatings, which is particularly relevant for modern construction challenges. Further research in the field of epoxy chemoelectrets will expand the application boundaries of these materials in construction.
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Evaluation of timber-fiber reinforced polymer composite systems: experimental study and reliability analysis

https://doi.org/10.58224/2618-7183-2025-8-3-9
Abstract
Timber, an ancient material widely used in construction, possesses unique properties but exhibits relative brittleness, particularly in bending. To enhance the performance and reinforce wooden structures, the incorporation of fiber-reinforced polymer (FRP) components has been proposed as a viable solution. However, the timber-FRP system has received less attention compared to the concrete-FRP system in literature, resulting in limited prediction models. Thus, the reliability of these models requires further examination. This research presents an experimental investigation aimed at evaluating the bond strength of timber members strengthened by FRPs, utilizing a pull-out test with various FRP sheets and adhesives. The acquired data is combined with existing experimental data from the literature to propose a novel probabilistic regression model. Furthermore, a comprehensive reliability analysis of the timber-FRP system is conducted by gathering models previously presented by researchers. These models are then compared with the newly developed probabilistic models. Considering three loading levels and defining uncertainty in six influential variables, 192 first-order reliability analyses are performed in two scenarios: one incorporating the model factor and the other without it. The results reveal a significant decrease in the reliability index when uncertainties are considered during member design. The existing models exhibit an average reliability index decrease from 4.26 to 2.82. Additionally, as anticipated, the influence of the live/dead load ratio on determining the reliability index diminishes in the presence of uncertainties.
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The challenges of reusing thermal power plant wastes to produce cellular concrete modified with wollastonite

https://doi.org/10.58224/2618-7183-2025-8-3-10
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Abstract
This paper presents new approaches of reusing fly ash generated in thermal power plant in the manufacturing of cellular concrete. Therefore, the research novelty is to make a meaningful utilization of fly ash as a binder to improve cellular concrete properties. The study has showed that fly ash has pozzolana properties which can boost up mechanical strength, thermal insulation and durability of cellular concrete, which may lead to obtain high quality final product in comparison with traditional building materials. Moreover, utilization of fly ash facilitates both reduction of heat conductivity and reduction of concrete density. This properties make cellular concrete resistant to heat transfer. Physical, mechanical and thermal tests have been carried out during research. The study of type of dependence between cellular concrete durability and its mix design has a valuable practical importance since it supports to reach maximum durability in lightly consumption of binder. We may conclude that the utilization of fly ash in the amount of 295 kg/m3, while the cellular concrete density is equal to 600 kg/m3, allows to solve a number of problems such as damaging of human health and environment pollution and to develop energy efficient cellular concrete. The research included the results of cellular concrete mix flowability, density, moisture, strength properties and concrete grade equal to B2,5-B3,5 with a density of porous ash concrete equal to 600 kg/m³. The natural wollastonite was utilized in this research as a reinforcing material to improve the tensile stregnth of cellular concrete.
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Sustainable gypsum composites reinforced with basalt technogenic nanofiber

https://doi.org/10.58224/2618-7183-2025-8-2-2
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Abstract
Sustainable composites based on gypsum man-made stone are produced using a technology that excludes the firing stage. It meets the requirements for resource and energy conservation, does not harm the environment and can be used in the production of a number of biopositive building materials. The use of pure dihydrate gypsum from gypsum mold waste in the composition of sustainable gypsum composites predetermines the expansion of the scope of application of materials and products based on it. These wastes are characterized by stable physicochemical and mechanical properties. However, the features of the mineralogical composition require high costs for their use in the production of fired gypsum binders using classical technologies. Binders based on them have low strength and other physical indicators. Application without firing technology allows for the maximum use of all the unique properties of gypsum – creation of a comfortable environment, high resistance in fire conditions, good insulating characteristics, etc. By introducing highly dispersed basalt dust particles into the composition of stable gypsum composites based on dihydrate gypsum, gypsum stone is reinforced and compacted at the micro- and nanoscale levels. This is facilitated by the optimal values of the pressing force and humidity of the raw mix selected during the study. They are important technological parameters. The resulting high-strength gypsum composite is characterized by a fine-crystalline structure with higher performance indicators than conventional gypsum materials due to the screening of the moisture effect on it.
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Structure formation of composite materials based on technogenic soil modified by additives of high-molecular compounds

https://doi.org/10.58224/2618-7183-2025-8-2-3
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Abstract
The article substantiates the possibility of obtaining organo-inorganic composite materials with improved functional properties based on technogenic soil and high-molecular substances. The specific effective activity of natural radionuclides (226Ra, 232Th, 40K) of technogenic soil was 97±12 Bq/kg, which allows use in the production of building materials without restrictions. Using the methods of atomic emission spectrometry with inductively coupled plasma, infrared spectroscopy, differential scanning calorimetry and thermogravimetry, powder diffraction, scanning electron microscopy, data on the composition, properties and structural features of technogenic soil were obtained, allowing us to assess the possibility of its use as a dispersed filler for the composite. It was revealed that the organo-inorganic composite material is frost-resistant, waterproof, and is characterized by a compressive strength of 6.20 MPa and a thermal conductivity of 0.20 W/(m•K). The mechanism of composite structure formation was established, which consists in the reorganization of hydrate shells and the formation of organomineral complexes during the interaction of the polymer matrix and dispersed filler particles. The effectiveness of cryogenic treatment in transforming the pore space of the composite and improving its functional properties was shown. It was revealed that cryostructuring contributes to an increase in the pore volume of the composite by 1.4 times, which determines its thermophysical properties.
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Numerical simulation of nonlinear bending behaviour of uhpc beams

10.58224/2618-7183-2025-8-4-6
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This study presents an approach to finite element (FE) modelling in Abaqus FEA for analysis of the nonlinear bending behavior of ultra-high-performance fiber-reinforced concrete (UHPC) beams. The Concrete Damaged Plasticity (CDP) model was utilized to capture UHPC’s distinctive mechanical properties, including high tensile strength, nearly linear compressive behavior up to peak stress, and unique failure modes of UHPC beams compared to normal strength reinforced concrete beams. Experimentally validated constitutive laws available in literature for plain and fiber-reinforced UHPC under compression and tension were incorporated, with tensile behavior calibrated through inverse modeling based on average strains in the tensile zone of beams. Other CDP parameters, such as eccentricity, viscosity, and dilation angle, were established based on prior research on standard UHPC specimens and simulations of beams. Three-dimensional FE models of UHPC beams, featuring fiber volume fractions 1–2 % and longitudinal reinforcement ratios 0.31–5.13 %, were developed and validated against experimental data from the authors and other researchers. The model accurately predicts load-deflection curves, moment capacities, cross-sectional strains, cracking pattern, and localization of cracks at all loading stages. This FE modeling approach provides a reliable tool for design of UHPC beams, enhancing the structural performance of critical infrastructure, including bridges, viaducts, and marine structures, under complex loading conditions.
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