Sabitov L.S. – Строительные материалы и изделия

The effectiveness of internal hydrophobization of concrete in biologically aggressive environments

https://doi.org/10.58224/2618-7183-2026-9-2-8

Rumyantseva V.E., Konovalova V.S., Krasilnikov I.V., Strokin K.B., Novikov D.G., Nabiullina K.R., Sabitov L.S., Kiiamova L.I.

Abstract

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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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

Pshenichkina V.A., Ivanov S.Yu., Drozdov V.V., Sabitov L.S., Kiiamova L.I.

Abstract

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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Orientation-dependent mechanical properties of 3D-printed components fabricated by selective laser melting of metal powders

https://doi.org/10.58224/2618-7183-2025-8-6-12

Kashapov N.F., Kashapov L.N., Fazlyev M.R., Kiiamova L.I., Sabitov L.S., Aktyamova L.Sh.

Abstract

This study investigates the mechanical properties of aluminum alloys AlSi10Mg and AK9ch fabricated by selective laser melting (SLM), taking into account the build orientation (longitudinal, transverse, 45°) and applied heat treatment regimes (stress-relieving annealing, T6 treatment, prolonged aging). A comprehensive tensile test program was conducted to determine ultimate tensile strength, yield strength, elongation, and hardness. Results show that SLM-processed specimens significantly outperform conventionally cast AK9ch, especially after T6 treatment, achieving up to 285 MPa in strength with ~9% elongation. For the first time, it is demonstrated that the Russian casting alloy AK9ch is suitable for SLM technology, with post-treatment strength reaching 259 MPa and ductility ~5%, comparable to that of AlSi10Mg. The influence of build orientation was found to be negligible at high relative density (>99%). The findings confirm the potential of additive manufacturing to produce high-performance aluminum parts using domestic alloys, offering a promising path toward import-independent 3D production in Russia.

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Probabilistic analysis of the “multilayer soil – structure” system response to seismic load

https://doi.org/10.58224/2618-7183-2024-7-4-6

Pshenichkina V.A., Tchantchane M., Hamici S., Ayzatullin M.M., Sabitov L.S., Kiyamova L.I.

Abstract

Based on the analytical model of a horizontal layered medium, applying the probabilistic formulation, the article presents the results of the investigation of joint work of a structure and multilayer soil bed subjected to seismic loading. The damping properties of soil were taken into account. The authors drew a comparison between the fundamental frequencies of the free vibrations of the “soil - structure” system obtained using the layered medium model and the platform model. By the example of a two-layer soil bed, the dependence of the resonant frequencies of the system on the thickness of the near-surface or buried weak layer was determined.
The results of the analysis of the “two-layer soil - structure” system for seismic loads at various locations of the weak layer were presented. The seismic acceleration of the soil bed was modeled as a stationary random process with a given spectral density. The investigation included an analysis of the amplitude-frequency characteristics, acceleration spectral densities and dynamic coefficients for both the entire system and the individual layers. It was demonstrated that the resonant frequencies of an individual layer being a part of the multilayer system can differ significantly from the resonant frequencies of a homogeneous soil bed with similar dynamic characteristics. A comparison between the dynamic responses of the two-layer soil bed system and a system with the reduced characteristics of the soil bed was drawn at various parameters of the spectral density of seismic load. The intervals of possible values of the resonant frequencies of the system were determined taking into account the random variability of the velocity of transverse waves within each layer.

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The effect of temperature difference on bending of external panel walls

https://doi.org/10.58224/2618-7183-2024-7-3-6

Korol O.A., Degaev E.N., Sabitov L.S., Ayzatullin M.M., Kiyamova L.I.

Abstract

One of the most common structural systems of buildings intended for various purposes is a prefabricated panel system of factory-made elements assembled on-site. Single-layer structures made of lightweight concrete are widely used as envelopes of these buildings. In buildings operated under various climatic conditions, exterior wall panels, as well as other envelopes, are exposed to thermal deformations and, accordingly, changes in the stress-strain state. As the temperature changes, corresponding stresses and deformations occur across the thickness of the exterior panels. To analyze their values, the bending moments and support reactions of single-layer lightweight concrete panels of different length and thickness in the range of temperature differences from 0 °С to 65 °С have been calculated. It was found that the bending moments and support reactions of 1,500 mm long panels decrease as the thickness of the panels increases over the entire temperature gradient. The values of bending moments and support reactions of panels with length of 3,000, 4,500 and 6,000 mm decrease only when the temperature rises from 0 to 10 °С, in the rest of the range 15–65 °С – increase as the thickness of the panel increases due to the bending stiffness.

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Stress-strain state during the formation of normal cracks in three-layer bendable reinforced concrete elements under the action of longitudinal and transverse forces

https://doi.org/10.58224/2618-7183-2024-7-1-3

Korol O.A., Barabanova T.A., Abdullazyanov E.U., Sabitov L.S., Ayzatullin M.M.

Abstract

Most wall panels in operating multi-storey residential buildings are in a complex stress-strain state under the influence of vertical and horizontal loads, such as their own weight, wind, etc. These features must be taken into account in the calculation in order to ensure operational safety. The combination of vertical and horizontal forces acting simultaneously for three-layer bending elements leads to the fact that the boundary between the compressed and tensile zones not only moves from one layer to another, but also has a different geometric shape depending on the ratio between the vertical and horizontal load. The stress-strain state during the formation of normal cracks in three-layer bendable reinforced concrete elements is caused by the impact on layers of different concretes. The formation of normal cracks occurs due to the achievement of ultimate tensile strength by the most stretched concrete under the influence of external loads. Since three-layer reinforced concrete elements consist of two outer layers (reinforced concrete) and a middle layer (lightweight concrete), when such an element bends, the outer layers are subject to compression, and the middle layer is subject to tension. The boundary of the compressed zone can be located either in one of the outer layers or intersect the middle layer, which falls into both the compressed and stretched zones. To analyze the stress-strain state during the formation of normal cracks, it is necessary to take into account the fol-lowing parameters: geometric characteristics of the element (dimensions and shape of the section, layer thickness, etc.), physical and mechanical properties of concrete (compressive and tensile strength, elastic modulus, Poisson's ratio, crack resistance coefficient, etc.), characteristics of reinforcement (class, diameter, pitch of bars, etc.) and its location in the section.

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