The results of the specialists’ and scientists’ researches. Рубрика в журнале - Nanotechnologies in Construction: A Scientific Internet-Journal
Scientific article
Introduction. Currently one of the focus areas for the development of construction material science is the creation of self-cleaning concretes characterized by polydisperse multicomponent composition with the presence of nanoscale photocatalytic additives, primarily based on TiO2. These photoactive modifiers give the material a number of positive properties, including the ability to decompose atmospheric pollutants, to self-clean the surface, etc. The promising method for improving the functional characteristics of titanium oxide photocatalysts is the creation of nanostructured systems with ‘core (substrate) – shell (photocatalyst)’ architecture. Previous research results show that the final efficiency of the synthesized composite photocatalytic modifiers largely depends on the level of substrate reactivity in the cement system. The purpose of this study is to investigate the impact of three types of siliceous rocks (diatomite, trepel, and opoka) on cement stone formation processes and to identify the most effective raw materials for use as photocatalytic carriers in self-cleaning concrete compositions. Methods and materials. The methods of Kozeny-Karman, laser diffraction and X-ray fluorescence spectrometry were used to determine the specific surface area and parameters of granulometric and chemical compositions of silicite samples. The phase composition of siliceous rocks and modified cement systems was studied by X-ray powder diffractometry. Results and discussion. The main parameters of granulometric composition of diatomite, trepel and opoka were determined. The predominance of reactive modifications of free silica (47.6–78.0 wt. %), represented by amorphous opal-A or cryptocrystalline OCT-phase (opal-CT), were revealed in the structure of silicites. It was found that increasing the dosages of silica-containing additives from 0 to 10% resulted in decreased by 10–27% in the quantity of portlandite in the phase composition of cement stone aged 28 days, while the content of high-strength low-basic calcium hydrosilicates (C–S–H (I)) increased by 11–27%. Conclusion. The chemical and mineralogical composition peculiarities of silicites, as well as the nature of the impact of silica-containing modifiers on the structure formation processes of cement systems, determine the prospects of using opal-cristobalite rocks as dispersed photocatalyst carriers for self-cleaning concrete.
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Stress-strain properties of polymer-based composite materials according to experimental evidence
Scientific article
Introduction. The use of polymer composites as structural materials for bridge superstructures represents a promising area for scientific research and development, particularly in challenging climatic and geological engineering conditions. The use of polymer composites as structural materials for bridge superstructures represents a promising area for scientific research and development, particularly in challenging climatic and geological engineering conditions. The aim of the work is to identify methods for increasing the efficiency of using polymer composite materials in bridge span structures based on the study of their physico-mechanical characteristics as part of experimental studies. Methods and materials. The relevance of this research stems from the need to develop a structurally similar model of a bridge superstructure made of polymer composite materials that meets modern stability and safety requirements, thereby facilitating infrastructure development in remote northern regions. The variety of fibers, matrix materials and reinforcement schemes used in the creation of polymer composite structures makes it possible to control characteristics such as strength, rigidity, operating temperature and other physical and mechanical properties of materials. Results and Discussion. The study included a brief overview of the components of polymer composite materials and the development of a testing program, which led to the production and testing of a batch of flat samples using domestically produced materials. Selecting the composition, adjusting the component ratios and improving the composite's macrostructure allows for optimal performance characteristics depending on the requirements. Conclusion. Tests of flat FRP samples aimed at determining the values of their physico-mechanical, strength and deformation characteristics have been carried out. The test results obtained for FRP are comparable to those of traditional structural materials. The expediency of using fiberglass in highly loaded structural elements is substantiated, which demonstrates the potential for developing a bridge superstructure design from FRP. The prospects for further research based on computational and experimental analysis of nodal connections of elements from FRP are outlined.
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Structure formation in the «clay soil – carbide sludge» dispersed system
Scientific article
Introduction. Clay soil is a multiphase, multicomponent aluminosilicate dispersed system with specific properties determined not only by its composition but also by the formation of coagulative and transition contacts (binds) between the soil particles. One of the methods of changing soil properties is the introduction of active mineral additives that promote the formation of phase contacts (binds) between soil particles as a result of the pozzolanic reaction. The effectiveness of using carbide sludge, which is a multi-tonnage lime-containing waste (the content of active calcium oxide reaches 56%) as an additive, has been proved. However, to date, the proposed mechanism of interaction in the «clay soil – carbide sludge» system is based only on the literature data and has not been experimentally verified. The purpose of this research is to study the mechanism of structure formation in the «clay soil – carbide sludge» dispersed system. Methods and materials. A soil model has been created by mixing saponite-containing material with sand, which corresponds to the composition and properties of sandy loam. The carbide sludge in the form of a suspension was selected from the sludge collector, dried to a constant mass and sieved. Microstructural analysis, differential thermal analysis (DTA), and X-ray phase analysis were used to study the mechanism of structure formation. Results and discussions. Based the results of the differential thermal analysis, there is a decrease in the intensity of the endothermic effect in the range of 460 to 470°C associated with the decomposition of calcium hydroxide in the treated sample. Additionally, an endothermic effect is observed at 750°C, which indicating the decomposition of calcium silicate hydrate. The results of differential thermal analysis are confirmed by X-ray phase analysis, which shows the presence of tobermorite group hydrosilicates in the reaction medium. The study of the microstructure of the analyzed mixtures revealed a decrease in the specific volume of pores with a diameter of 4–5 nm in the modified clay soil. This is associated with gelling from particles of new hydrate formations. Besides that, the volume of pores with a diameter of more than 6 nm increased, which indicates the process of contraction. Conclusion. The mechanism of structure formation in the «clay soil – carbide sludge» system has been established.
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Scientific article
Introduction. This paper examines the original design of a high-temperature tubular electric heater cartridge designed for heating industrial tooling used in the production of VT6 alloy parts. The process requires maintaining stable high temperatures exceeding 1000 °C. Without proper heat treatment after welding, cracks form in the components, which can lead to subsequent failure. This becomes especially critical when the structure of the weld and base metal is highly heterogeneous, ranging from nanoscale to coarse-grained. Furthermore, undesirable thermal effects on tooling components require additional costs for cooling and monitoring. The aim of the research is to evaluate the heat transfer of the original design of electric heaters used in the production of parts from VT6 alloy. Methods and Materials. The heat transfer study of the proposed heater design was performed using the finite element method in the Ansys software package, using the Transient Thermal calculation module. To validate the calculated values, a test rig was developed that reproduced the simulation results. A qualitative analysis of the temperature fields confirmed the hypothesis of uniform operation of the proposed heater design. Results and discussion. A quantitative analysis reflected the heating conditions of the VT6 alloy. The temperature modeling results at tooling control points were experimentally confirmed, ensuring that the target temperature of 1000 °C was achieved in a localized zone. The error was ± ≈ 70 °C. The microstructure of VT6 titanium alloy samples was examined in various zones after heat treatment. Conclusion. Based on the conducted research, recommendations are proposed for selecting optimal operating conditions for high-temperature tubular electric cartridge heaters of this design, and their potential applications are described.
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Scientific article
Introduction. Literature analysis and patent search revealed that basalt rock and its fibers have exceptional physical and technical characteristics and alongside abundant raw material reserves. Based on this, the use of basalt rocks and their fibers as a material for the development of advance composite materials with high performance characteristics is a promising direction. Diverse technological fields and economic sectors, as well as various material requirements, necessitate a spectrum of systems, compositions, and properties for basalt and its melts, whether for generating superthin or continuous fibers. Methods and materials. The chemical and mineralogical compositions of some basalt rocks from deposits in the Kyrgyz Republic were studied to determine their suitability for production of superthin fibers and continuous fibers. The acidity modulus and fusibility modulus were determined by calculation based on the chemical composition of basalts of the Kyrgyz Republic. Among them, the quality of basalts from the Suluu-Terek deposit and basalts from the Toru-Aigyr deposit fully meets the requirements for the quality of raw materials for creating the production of basalt superthin fibers (BSF) and basalt continuous fibers (CBF). In the research we used physical and chemical analysis methods to determine the chemical and mineralogical composition of basalt. By calculating the acidity and fusibility modulus of basalt raw materials from the Kyrgyz Republic, as well as comparing them with relevant standards, their suitability for the production of basalt superthin fiber (BSF) and basalt continuous fiber (CBF) was established. The object of the study was the basalts of the Sulu-Terek deposit. Results of the study include an analysis of the chemical and mineralogical compositions of certain basalt rocks from deposits in the Kyrgyz Republic in order to assess their suitability for the production of superthin and continuous fibers. The acidity modulus and fusibility modulus of basalts of the Kyrgyz Republic were determined by the calculation method. Among them, it was revealed that the quality of basalts from the Suluu-Terek deposit and basalts from the Toru-Aigyr deposit fully meets the requirements for the quality of raw materials for the production of basalt superthin fibers (BSF) and basalt continuous fibers (CBF). Conclusion. The suitability of basalt rocks from various deposits, especially Suluu-Terek, Taldy-Bulak and Kashka-Suu, was confirmed, with recommendations for use. The results also highlight the importance of compliance with standards when selecting deposits and setting production parameters.
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Scientific article
Introduction. The article discusses how artificial wood aging affects the retention of its fireproofing efficiency to evaluate the ability of a fire-bio-moisture-resistant impregnating agent to protect facing timber materials of facade systems exposed to weathering, such as varying temperature and humidity, if standardized levels of fire hazard and integrity are maintained and the impregnating agent has water-soluble phosphorus and nitrogen compounds of the nanoscale range. Research focus and methods. A specimen of pine wood was subjected to artificial aging for 120 days, which is equivalent to 15 years of outdoor operation. The method of pressurized impregnation was applied to pre-treat the specimen with the fireproofing agent. Climate testing was followed by a comparative evaluation of combustibility parameters according to a standard experimental method used to distribute combustible and hardly combustible materials between combustibility groups. Besides, before and after aging, all surfaces of fireproof wood specimens were subjected to thermo-analytical studies and visual inspection. Results and discussion. Results of combustibility group identification and principal thermal decomposition parameters of fireproof pine timber remained nearly the same before and after climate testing. Further comparative visual examination of surfaces of timber specimens identified no external changes. Conclusion. Research on the stability of fireproofing properties in pressure-impregnated timber shows that it can retain its effectiveness for up to 15 years under natural weathering conditions.
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The photocatalytic activity of cement-sand plaster under the influence of natural solar radiation
Scientific article
Introduction. Concrete and cement composites can be considered as the most demanded and versatile building materials nowadays. Recently, photocatalytic building materials containing nano- and finely dispersed oxides and salts photocatalyst particles, especially titanium dioxide of anatase modification, are becoming widespread. Under the influence of light, the surface of these materials becomes capable of self-cleaning. The materials photocatalytic activity is usually determined in the laboratory conditions by irradiating samples with an artificial source of light with certain wavelength, which does not fully characterize the behavior of the material in real-life conditions. Therefore, the purpose of this study is to evaluate the photocatalytic activity of cement-sand plaster samples under natural solar radiation. Materials and methods of research. In this study, the properties of cement-sand plaster modified with an additive of industrial TiO2 were studied. The additive was introduced into the plaster compositions in amounts of 0.3; 1.0; 1.7; 3.0; 5.0 and 10.0 wt.% during the dry mixing of the components. At the first stage, the effect of the additive on physical and mechanical properties of the samples was investigated. The second part of the research is devoted to the study of the photocatalytic properties of the material. Mineralization of the model pollutant Methylene blue was carried out in real-life conditions under sunlight irradiation, the photocatalytic activity of the samples was evaluated in accordance with the European standard UNI 11259-2016. Results and discussion. As a result of the study, the authors found that the maximal increase in compressive and flexural strength corresponds to the sample with 5.0 wt.% of TiO2, and the maximum degree of Methylene blue decomposition corresponds to the sample with 10.0 wt.% of TiO2. Thus, compressive strength increases by 69% at 2 days age, by 58% at 7 days age, and by 50% at 28 days age compared to the control sample. Flexural strength increases by 10, 13, and 50% at 2, 7, and 28 days age, respectively. The strength of the samples with 10.0 wt.% of TiO2 remains approximately at the level of the control sample. Compositions with TiO2 starting from 3 wt.% demonstrate photocatalytic activity (R), the highest R corresponds to 10 wt.% sample with R value is 40–78%. It is also noticeable that the maximum Methylene blue mineralization (58–78%) is observed after 2 days of sunlight irradiation, after 7 days there is a significant decrease in the degree of pigment decomposition. Conclusion. As a result of the research, the authors concluded that the optimal amount of TiO2 photocatalyst in the cement-sand plaster is 5.0–10.0 wt.% since these samples exhibit maximum strength characteristics combined with a high ability of model contaminant degradation.
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The physical and mechanical properties of concrete with multifunctional additive
Scientific article
Introduction. It is known that concrete is the main building material, despite the introduction of new technologies. The combination of strength and durability makes this material indispensable for the construction of civil and industrial infrastructure. However, the impact of aggressive external factors on concrete structures, such as an acidic or alkaline environment, temperature fluctuations, and the presence of water at low temperatures, can lead to a significant decrease in their strength characteristics. The introduction of various additives based on organic and inorganic compounds into the composition of concrete allows for the regulation of its performance properties and protect concrete structures from the negative impact of the environment. Therefore, research works aimed at improving physical and mechanical properties and quality of concrete structures are relevant. Methods and materials. The objects of our research were concrete samples, prepared with and without the use of a multifunctional additive called “Betomix-ITH Gel”, which was developed by the researchers of the Institute of Theoretical and Applied Mechanics of the Ural Branch of the Russian Academy of Sciences (ITC UB RAS). The physical and chemical properties of the compared samples were studied in accordance with Russian and interstate regulatory documents in accredited laboratories of the Russian Federation and the Republic of Turkey. Results and discussion. As a result of the research, we have found that the introduction of the multifunctional additive "Betomix-ITH Gel" to the concrete mixture significantly increases the water resistance, frost resistance, and strength of concrete samples, compared to samples without the additive. It has been shown that Betomix-ITH Gel imparts the property of "self-healing" to concrete, with cracks up to 0.5 mm in size, and increases the resistance of steel reinforcement to corrosion. Conclusion. The research has proved experimentally the effectiveness of the Betomix-ITH Gel additive for improving the quality characteristics for concrete of various classes, which allows the use of this additive in concrete mixtures in the construction of reinforced concrete structures located in aggressive conditions.
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Scientific article
Introduction. In the context of the global fight against climate change, the reduction of CO2 emissions and its utilization is a topical theme. One of the promising directions is the utilization of CO2 in construction, in particular, in concrete production. The present research investigates the effect of carbon dioxide on the formation of nanoscale structure and physical and mechanical properties of concrete mixtures. Methods and Materials. A special unit for mixing cement, sand, water and CO2 under pressure was developed for the research. The obtained concrete specimen were subjected to compressive and flexural strength tests using MATEST E161-03N automatic dual range testing press. The microstructure of the specimen was also analyzed using scanning electron microscope (SEM). Discussion. The experimental results showed that the introduction of CO2 into the concrete mixture promotes the formation of nanoscale structure, which improves its strength properties up to a certain pressure. With further increase in pressure, deterioration of these characteristics is being observed. Additional mixing time and increase in water volume also affect the strength of concrete and its microstructure. Conclusion. The use of CO2 in concrete production can significantly reduce the carbon footprint of construction materials and improve their physical and mechanical properties due to the formation of nanoscale structure. Further research and optimization of mixing parameters are necessary to create stronger and more stable concrete mixtures.
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The study of the formation of a hollow cellular structure with a given geometry
Scientific article
Introduction. The use of superplastic forming technology presents a number of challenges, including the lack of experimental and analytical data and the absence of specialized processing facilities. Another crucial factor limiting the widespread use of this methodology is the uniqueness and complexity of the equipment for performing the superplastic forming operation. The study is aimed at determining the optimal shape of the primary blank for the superplastic forming (SPF) process in order to obtain acceptable elongation of the bridges and minimal shrinkage. Methods and materials. Titanium alloy grade VT-6 was used as the material for obtaining the samples. The shape of the initial workpiece was optimized using a model sample, in which the ratio of the height and width of the fillets varied from 3:2 to 3:6 mm. The sample was obtained from a sheet 5 mm thick, by mechanical processing. The two halves of the sample were pre-welded together along the contour using argon-arc welding and sealed after pumping out the air from the cavity between them. Diffusion welding of the sample took place in an autoclave. The SPF was carried out in a limiting container at a temperature of 900±10 °C, argon was supplied according to the law ensuring optimal metal drawing in superplasticity modes. The width of the welded surfaces was from 2 to 4 mm. Modeling and finite element analysis of the SPF process were performed in the MSC Marc software package. The microstructure of the samples was studied using an Altami MET 1C microscope (with a USB 3.0 5 MPix camera). Results and discussion. The results of finite element analysis and a full-scale experiment of SPF are presented to verify the modeling results. During the research it was found that in order to minimize the depth of the resulting sink marks it is necessary to ensure an optimal ratio of the fillet radii equal to 3:5 and 3:6. The difference in the width of the platforms before SPF and the lintels formed after SPF was determined. The smallest narrowing of the lintels is characteristic of the widest platforms. Conclusion. The combined use of finite element modeling and a full-scale experiment made it possible to preliminarily identify the optimal ratio of the height and width of the outer fillet, which allows for acceptable elongation of the bridges and minimal shrinkage.
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Trends in the development of industrial robotic manipulators
Scientific article
Introduction. Industrial robotic manipulators are becoming an integral part of modern enterprises due to their versatility and ability to perform complex operations with high precision and speed, including in extreme conditions. Effective implementation and operation of robotic manipulators requires an understanding of their design features, control methods, and manufacturing technologies. Main part. This review presents a classification of robotic manipulators based on their design features, number of degrees of freedom, and drive types. Their application areas and market trends are analyzed. This review points to the steady growth of the industrial robotic manipulator market, driven by the transformation of production processes in line with the concept of Industry 4.0. This article examines the structural components of robotic manipulators: the mechanical part, the drive, and the control system. It also presents an overview of modern materials used in the production of manipulators. A method for enhancing the performance properties of structural components through the use of materials with a nanocrystalline structure is proposed. Current development trends in industrial robotics are identified. It is noted that the integration of machine vision and artificial intelligence into manipulator control systems is becoming a key trend in robotics. Such solutions enable rapid response to changing operating conditions and the prevention of potential accidents. Conclusion. Industrial robotic manipulators continue to evolve, opening up new opportunities for automation and increased efficiency in production processes. Their further improvement requires an interdisciplinary approach combining engineering, software, and technological solutions. The results of this review can be used for selecting, designing, and implementing industrial robotic manipulators in enterprises, as well as for further scientific research in the field of robotics.
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Сlassification of chemical elements according to the electronic structure of their atoms
Scientific article
It is widely acknowledged that the development of chemistry, both historically and in the present day, is fundamentally rooted in D.I. Mendeleev's discovery and the Periodic Table of Chemical Elements, which has been in use for over 150 years. This study proposes a novel conceptualization of chemical elements structured as a three-dimensional matrix. This approach enables the prediction of new elements, including the determination of their nuclear masses and electron shell configurations. New regularities concerning the cyclic and block structures of horizontal periods have been formulated, while the structure of vertical groups and their physical interpretation have been refined. The findings indicate that the Periodic Law fundamentally relies on the system of two equations. According to these equations, block energy increases cyclically, approaching near-zero values from negative ones in the “8s” block. The authors propose that the existence of chemical elements in nature culminates with the “8s” block. Thus, the total number of chemical elements that can exist in nature is evidently 120.
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