The results of the specialists’ and scientists’ researches. Рубрика в журнале - Nanotechnologies in Construction: A Scientific Internet-Journal
The photocatalytic activity of cement-sand plaster under the influence of natural solar radiation
Статья научная
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
Статья научная
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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Статья научная
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
Статья научная
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
Статья научная
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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