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Toward protection of urban stone structures from decay using pleurotus ostreatus: mycokarst self-healing material

https://doi.org/10.58224/2618-7183-2026-9-2-4
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Аннотация
The ongoing decay of urban stone structures creates a need for smart materials that enhance durability over the life cycle. Biotechnologies based on fungus Pleurotus ostreatus are explored as a method to strengthen substrates prone to destruction in this study. Their ability to alter properties and adapt to extreme conditions provides the basis for self-healing, strong, resilient, and environmentally friendly biocomposites. Some fungal strains are known to precipitate calcium carbonate (CaCO3) and to heal cracks in concrete, while Pleurotus ostreatus stimulates calcium oxalate (CaOx) formation. The study investigates whether these microorganisms are able to facilitate carbonate biomineralization without compromising their ability to act as natural sealants. The resulting Mycokarst material, formed from CaCO3-based karst soil, rice, dolomite flour, and Pleurotus ostreatus mycelium, demonstrated cyclic self‑healing and strength gain. It promotes self-strengthening of weak karst soils and stone structures through the formation of mycelial and limestone frameworks without external intervention. Mycokarst represents a new generation of smart biocomposites and offers a green approach to protecting urban mineral-based infrastructure from decay, while reducing CO2 emissions and environmental impact and minimizing human and technological interference with construction and restoration.
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Autogenous shrinkage of cement and concrete with superplasticizers of various chemical bases

https://doi.org/10.58224/2618-7183-2026-9-2-5
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Аннотация
Introduction. The stress-strain state of massive monolithic reinforced concrete structures during the early stages can cause cracks due to temperature deformation and autogenous shrinkage of concrete. Ignoring the deformations caused by autogenous shrinkage in calculations of the stress-strain state is often an unjustified simplification. This emphasizes the importance of studying the influence of formulations and technological factors on the amount and rate of autogenous shrinkage in concretes. The kinetics of autogenous shrinkage, especially during the first two days of hardening, can vary significantly depending on the specific characteristics of the cement and superplasticizer used. The aim of the study. To investigate the influence of the type of cement and superplasticizers with different chemical basis on the magnitude and kinetics of autogenous shrinkage and to obtain the necessary equations for calculations of thermally stressed states in the early stages. Methods. Analysis of existing approaches to assessing autogenous shrinkage in cement paste and concrete. Experimental study of autogenous shrinkage of cement pastes. Comparison results with published data and EN and JSCE standards. Results. Based on the proposed equation a classification of autogenous shrinkage kinetic of cements is proposed. The kinetics of autogenous shrinkage was varied: at the age of one day, the amount of autogenous shrinkage relative to seven days can vary up to six times, at the age of three days up to two times. An equation of the dependence of autogenous shrinkage on concrete strength is proposed for calculating the thermally stressed state of massive monolithic structures in the early period.
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Modeling of an engineering method for calculating the thermal stability of walls with a shielded external surface

https://doi.org/10.58224/2618-7183-2026-9-2-6
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Аннотация
This paper presents a modeling methodology for an engineering calculation of the thermal stability of external walls with a shielded outer surface forming a ventilated façade system. The objective of the study is to develop a practical design tool for assessing the amplitude attenuation and phase shift of the internal surface temperature under daily climatic fluctuations. The method is based on the solution of a one-dimensional transient heat conduction problem for a multilayer structure subjected to periodic climatic effects. The external boundary condition is defined through an equivalent heat transfer formulation that accounts for shortwave solar radiation, longwave radiative exchange between the screen and the ambient environment, convective heat transfer, and possible ventilation of the air cavity. An engineering calculation algorithm is proposed that incorporates the effect of equivalent solar loading and harmonic variations of outdoor air temperature with high amplitudes of environmental and near-wall air layer fluctuations. A numerical procedure is provided for the “screen – air gap” subsystem, followed by the evaluation of internal surface temperature attenuation and transient heat transfer characteristics. Validation against numerical simulations and experimental data demonstrates a deviation not exceeding 5-10%. The results indicate a significant influence of screen reflectivity, air gap ventilation intensity, and wall heat capacity on improving thermal stability and reducing heat gains during the hot season. The proposed enhanced assessment algorithm can be widely applied in design practice, including the selection of thermal insulation thickness for building envelopes in southern regions, the determination of design loads for ventilation and air-conditioning systems, and the evaluation of indoor thermal conditions under intermittent heating and ventilation regimes. The practical significance lies in the ability to optimize façade system parameters with shielded external surfaces to prevent overheating and improve building energy efficiency. The study is conducted within the framework of ensuring thermal safety of buildings in warm climate conditions.
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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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Аннотация
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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Аннотация
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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Аннотация
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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Аннотация
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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Аннотация
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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Аннотация
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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Аннотация
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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