Kiiamova L.I. — 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.

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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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.

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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Experimental analysis of a new high-tech method of strengthening reinforced concrete structures based on the use of metal and CFRP materials

https://doi.org/10.58224/2618-7183-2025-8-6-9

Georgiev S.V., Mailyan D.R., Solovyeva A.I., Che Xiang Yu, Kiiamova L.I.

Аннотация

This paper presents a large-scale experimental analysis of a new high-tech method for strengthening reinforced concrete columns using metal and CFRP materials. The research is justified by evaluating existing traditional and modern methods of strengthening reinforced concrete compressed elements, identifying their main drawbacks, and taking these into account, a new strengthening method was developed. To study the large-scale effect of the new high-tech metal and composite-based strengthening method, two groups of a total of 46 reinforced concrete column samples with different flexibilities were designed and tested for central and eccentric compression until failure. The main test parameters included column flexibility, load application eccentricity, internal and external metal reinforcement, spacing, and cross-sectional area of composite strengthening. The study investigated the influence of the above-mentioned variable factors on the failure pattern, ultimate strength, peak stress, and deformation characteristics of columns strengthened with carbon fiber composite materials (CFRP). The results showed that reinforced concrete columns strengthened with CFRP, having the same dimensions and tested under the same load application eccentricities, demonstrated different increases in ultimate strength compared to unstrengthened columns. Peak stress increased with an increase in the cross-sectional area of metal reinforcement and decreased with an increase in the distance between composite stirrups. Ultimate axial strains of strengthened samples increased with a decrease in the distance between composite stirrups. The difference in the cross-sectional area of composite strengthening did not have a significant impact on the load-bearing capacity and ultimate strains of reinforced concrete strengthened structures.

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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.

Аннотация

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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