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Features of the pyrolysis process of waste batteries using carbon black as an additive in the construction industry

https://doi.org/10.58224/2618-7183-2023-6-6-4
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Аннотация
The paper discusses the technology for recycling used lithium-ion batteries. At the same time, one of the important components in the technology for processing such waste is the recycling of anode material with the extraction of graphite or carbon black, which can be used in the production of fire bricks. It has been shown that materials and compounds contained in lithium-ion batteries are sources of hazardous waste of the second hazard class. At the same time spent accumulators are a source of valuable secondary material resources and contain in their composition up to 16 % wt. % of graphite.The paper proposes to consider the process of processing anode materials of lithium-ion bat-teries in order to obtain graphite and carbon black from them by pyrolysis. Experimental studies were carried out on the process of decomposition of cathode and anode materials of lithium-ion batteries separately, as well as their mixture by pyrolysis. When studying the kinetics and mechanism of pyrol-ysis of carbon-containing materials, thermogravimetric analysis of the following materials was carried out: 1) powdered graphite grade GAK-2 (GOST 10273-79); 2) graphite released from the anode dur-ing manual disassembly of the LKIT; 3) mechanically activated powders containing cathode material LiNiMnCoO2. The characteristics of the pyrolysis process were assessed using thermogravimetric and differential thermogravimetric analyses. Pyrolysis characteristics demonstrate that organic substances contained in batteries can decompose at a pyrolysis temperature of 500 °C for cathode materials and 450 °C for anode materials. This subsequently leads to higher efficiency in the extraction of valuable components with shorter grinding times. It has been shown that the decomposition of a mixture of lith-ium-ion battery materials removes a larger amount of organic components than the pyrolysis of anode and cathode materials separately. In this case, the rate of decomposition of the mixture of materials occurs more slowly. The activation energy values for lithium-ion battery materials after the pyrolysis stage were determined. The content of components in powder obtained after the pyrolysis stage was determined using the method of atomic emission spectrometry with inductively coupled plasma.
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Dry mixes on gypsum and mixed bases in the construction of low-rise residential buildings using 3D printing technology

https://doi.org/10.58224/2618-7183-2023-6-6-5
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Аннотация
3D-printed building construction technology is developing in most countries, such as France, China, Russia and others, and the dry mixes and equipment used are being improved. The development of 3D-printing construction technology is dictated by its many advantages: architectural diversity, speed and automation of the technological process of construction of buildings and structures with a noticeable reduction in the cost of production. However, there are a number of problems of this technology that are waiting for optimal solutions. The paper proposes solutions to two such problems: firstly, the choice of mixture with gypsum and gypsum-cement binders, ensuring the continuity of the 3D printing process of the building and allowing the construction of buildings up to three floors with sufficient safety margin, high seismic stability, as well as with good heat and noise insulation; secondly, the design of buildings with a rational structural and technological solution of the roof and floor, allowing the interface of these structures with load-bearing printed walls.
Different compositions of dry mixes were tested in a series of field tests of large-sized wall blocks made with the use of a construction 3D-printer and filled with especially light porous expanded claydite, expanded clay concrete or heat-insulating foam gypsum with subsequent testing on press equipment of increased load-carrying capacity (with determination of bearing capacity and deformability of the large-sized block).
When designing low-rise buildings, erected by additive technology, as an optimal design of floors, it is proposed to use frame-monolithic beam structures made of metal thin-walled steel galvanized profiles, filled with foam gypsum mix, providing heat and noise insulation and covered with a thin layer of high-strength self-leveling gypsum mix, providing the necessary structural strength of the floor and, accordingly, the minimum load on the foundation.
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Investigation of the stress-strain state of domical masonry vaults

https://doi.org/10.58224/2618-7183-2023-6-6-6
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Аннотация
The results of analytical study of stress-strain state of one of the varieties of vaults erected in various function buildings, i.e. domical masonry vaults covering Orthodox churches, are presented in this article. Due to the ongoing restoration of architectural monuments and religious buildings, as well as in connection with the construction of such facilities as Orthodox churches, the study of stress-strain state of masonry arches and vaults has become especially important in recent decades. Despite the rapid development of new building technologies in the construction of temples, use of these new technologies is shown to be limited and focused on the use of traditional materials. The current level of engineering of building structures with the use of software enables to significantly improve the calculation models and to obtain more reliable results, in particular for the structures under consideration. The domical vault considered herein is formed by wall extensions inclined along a given curve, converging in a horizontal crown under rectangular plan or in one point under square plan. The authors of the article have performed calculations of vaults in both linear and nonlinear formulations, with the results thereunder the forces and deformations of vaults have been analyzed. As a result profiles of vertical pressures and lateral pressures of the vault mounting groups, isopoles of principal stresses, vertical displacements, bending moments and normal forces were calculated.
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Failure criterion for concrete under volumetric stress state conditions

https://doi.org/10.58224/2618-7183-2023-6-6-7
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Аннотация
Based on the experiments conducted by the authors, a six-parameter failure criterion for concrete has been developed, which makes it possible to take into account the volumetric stress state in strength calculations of massive concrete and reinforced concrete structures. The developed strength criterion is adapted to a spatial eight-node finite element (solid type) and implemented in the PRINS software. To verify the developed criterion, the work provides a com-parison with both experimental data and calculation results that meet other strength criteria widely used for concrete. Thus, the compression and tension meridians of the developed fracture criterion were compared with experimental data, as well as with the Willam & Warnke criterion and the modified Drucker & Prager criterion with Mohr & Coulomb constants. A comparison of compression meridians shows that in the mode of low hydrostatic stresses , these criteria converge with each other and with experimental data. In the mode of average hydrostatic stresses , the criterion proposed by the authors and the Willam & Warnke criterion show similar results, while the modified Drucker & Prager criterion shows on 20% overestimation of the failure value.
In the mode of high hydrostatic stresses , the Willam & Warnke criterion in com-parison with the proposed criterion and experimental data, gives an underestimated value of concrete failure.
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Assessment of the quality of the urban environment in the process of construction project management

https://doi.org/10.58224/2618-7183-2023-6-6-8
Аннотация
Recently, the construction of residential buildings in the Russian Federation has been carried out at an accelerating pace, not only in large cities, but in almost all regions of our country. In the current conditions, the issues of rational planning of residential development within the framework of urban construction development are becoming increasingly relevant. At the same time, an important role is assigned to the methods of assessing the quality of such planning. The analysis of the available methods of this kind carried out by the author indicates that at the moment, there are practically no adequate and objective methods for quantifying the degree of accessibility of critical social infrastruc-ture facilities of the city in relation to newly constructed or already existing residential buildings.
Based on the results of the applied research carried out within the framework of writing the pre-sented scientific work, the author proposed an innovative method for quantifying the degree of acces-sibility of socially significant urban objects relative to residential structures. The proposed methodolo-gy is unique in that, thanks to the use of such a universal and statistically accessible indicator as the average level of wages, experts have the opportunity to conduct a comparative assessment of the de-gree of accessibility of social objects, not only located within a walking distance, but also at longer distances, involving the use of public passenger transport.
The application of the methodology proposed in the framework of writing this applied scientific work for assessing the quality of the urban environment for the accessibility of socially significant in-frastructure objects relative to the location of residential buildings will allow, on a mathematically ac-curate quantitative basis, not only to assess the effectiveness of the work of regional state authorities and local self-government as qualitatively and objectively as possible, but also to conduct a compara-tive analysis of the quality layouts of newly designed residential neighborhoods. In addition, this tech-nique may be of practical interest to realtors and developers in the development and practical imple-mentation of various types of business processes, both in the field of housing construction and in the sale of residential buildings and premises.
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Vernacular architecture in the space of a modern city, based on deep learning methods and three-dimensional structural analysis

https://doi.org/10.58224/2618-7183-2023-6-6-9
Аннотация
This research paper describes the process and results of a project to automatically classify historical buildings using aerial photography and satellite imagery. New computational scientific methods and the availability of satellite images have created more opportunities to work on automated recognition of pieces of historical architecture. In this regard, the convolutional neural network (CNN) is the main classification approach within the project. As a result, the trained model is tested using a validation data set and has a roughly 98% accuracy. In addition, being affected by urbanization and other factors, local architectural heritage faces the challenge of introducing innovations for sustainable development, with originality and authenticity being preserved in redesign and planning. Thus, this study uses a visualized quantitative analysis to analyze the research trends in Russian vernacular architecture and study new ways of coexistence between vernacular architecture, object perception and cultural ecology. The most important task of this study is to analyze the theory of coordination between the emotion social and cultural structure and the cultural ecosystem in vernacular architecture. The main contribution of this study is the proposed concept of a subjective-cultural eco-design system for vernacular architecture sustainable development to establish a 3D structural analysis design paradigm and evaluation analysis matrix, and to ensure that vernacular architecture demonstrates the ability to self-renew by continuous exchange and revision in the dynamic cycle of the current design system.
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Improving Reinforced Concrete Column Strengthening Techniques for Reconstruction Projects Using Composite Jacketing Formworks

https://doi.org/10.58224/2618-7183-2023-6-5-1
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Аннотация
The paper looks at the issues of reconstruction of modern construction systems, in particular, the possibility of their functional repurposing. Examples from the global practice are provided to illustrate the conversion of industrial facilities for use as residential and public buildings. Based on an overview of scientific publications, the paper offers a set of rationales for the preservation of industrial facilities and highlights the benefits of reconstruction aimed at improving their residual lifespan and ensuring further reliable operation. Reconstruction is noted to enable resource savings, which allows efficiently investing in the development of modern machinery and technology as well as launching production of innovative products. Interior details are displayed as an example of industrial building conversion into a preschool educational facility.
The purpose of the study is to improve the techniques of enhancing the bearing capacity of reinforced concrete columns by using composite materials and reducing related labor inputs. To this end, it is suggested that removable or permanent formwork systems be replaced with a jacketing formwork combining the benefits of both removable formworks (quick turnaround, adaptability due to the use of high-strength and light-weight composites) and stay-in-place formworks (the factory-made decking forms part of the column to be reinforced and does not require extra finishing). The paper argues that a jacketing formwork is multifunctional, as it performs the protective function in addition to the molding one, and provides the description and schematic design featuring two formwork options. The use of jacketing formworks allows reducing labor inputs when reinforcing columns and restoring their geometric dimensions, thus cutting down on the overall reconstruction time.
A conclusion is made that the use of modern composite materials for manufacturing jacketing formworks allows not only making or reinforcing rectangular-section columns, but also changing the geometric configuration of the cross section for reconstruction purposes.
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Optimization of Rectangular and Box Sections in Oblique Bending and Eccentric Compression

https://doi.org/10.58224/2618-7183-2023-6-5-2
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Аннотация
The article presents a solution to the problem of finding the optimal ratio of the height of the cross-section to the width for a rectangular and box-shaped section in the case of oblique bending and eccentric compression. Optimization is performed according to the strength criterion, and for the case of oblique bending of a rectangular beam, a solution was also obtained from the condition of a minimum full deflection. For a rectangular section, the solution is made analytically, and for a box section, numerically using the MATLAB environment and the Optimization Toolbox package. As a numerical method of nonlinear optimization, the interior point method is used. To simplify the solution, the box section is assumed to be thin-walled, i.e. it is assumed that the wall thickness is significantly less than the height and width of the cross section. An estimate of the error of such an assumption is also performed. It has been established that in the case of oblique bending of a rectangular beam, when optimizing according to the strength criterion, the optimal ratio of the cross-sectional height to width is equal to the cotangent of the angle between the force plane and the vertical axis, and when optimizing according to the rigidity criterion, it is the square root of the cotangent of this angle. In the case of eccentric compression of a rectangular beam with eccentricities in two planes, the optimal ratio of the height of the cross section to the width is equal to the ratio of the eccentricity along the vertical and horizontal axes. For a box-shaped section, graphs of the change in optimal parameters depending on the angle between the force plane and the vertical axis in the case of oblique bending, as well as depending on the ratio of eccentricities along the axes in the case of eccentric compression, are plotted.
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Research Trends in the Mechanoactivation of Clay Minerals Used in Obtaining Geopolymers

https://doi.org/10.58224/2618-7183-2023-6-5-3
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Аннотация
The article is an attempt to review scientific achievements in the field of obtaining aluminosilicate geopolymers and current research trends in the field of mechanical treatment (mechanical activation or mechanoactivation, as the term is used in the article) of their predecessors. A geopolymer, also referred to in the literature as geopolymer resin and geopolymer cement, is a mineral binder resulting from geopolymerization, the main step of which is the polymerization (or polycondensation) of precursors in an alkaline or acidic medium. This review focuses on geopolymers whose precursors are natural aluminosilicates, i.e., clay minerals, because, firstly, clay minerals are widespread and available worldwide, and secondly, geopolymers based on heat-treated kaolinite (or metakaolin) have a number of advantages that make kaolinite attractive for further study in terms of reducing energy consumption and carbon footprint in their manufacturing. On the other hand, the review considers the potential of mechanoactivation of clay minerals in an air medium and establishes that mechanoactivated kaolin clays have the potential to replace metakaolin.
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Study of the Influence of Hydrothermal Treatment Parameters on the Properties of Lightweight Silicate Bricks Using Aluminosilicate Microspheres and Substandard Clay Rocks

https://doi.org/10.58224/2618-7183-2023-6-5-4
Аннотация
This article investigates the influence of various parameters of hydrothermal treatment on the properties of lightweight silicate bricks obtained using substandard clay raw materials, construction lime and aluminosilicate microspheres. It was found that it is possible to obtain products with the required performance characteristics at a minimum hydrothermal treatment pressure of 0.2 MPa. With an increase in pressure to 0.4 MPa, it is possible to reduce the time of isothermal exposure while main-taining the required properties, which helps to reduce the energy intensity of production. The optimal amount of CaO depends on the specific parameters of hydrothermal treatment. So in order to achieve maximum strength indicators, the content of CaO is 10 wt. % at a pressure of 0.2 MPa and 15 wt. % at a pressure of 0.4 MPa, respectively. The addition of aluminosilicate microspheres makes it possible to significantly reduce the average density and obtain a lightweight silicate brick with this indicator from 930 to 1610 kg /m3. The rational time of isothermal exposure, ensuring the formation of a cementing compound of optimal composition, and as a result, obtaining a material with high physical and me-chanical properties at a pressure of 0.2 MPa is 8 hours, and at a pressure of 0.4 MPa is 6 hours. Math-ematical models are proposed for the selection and optimization of lightweight silicate brick compositions based on construction lime, substandard clay rocks and aluminosilicate microspheres.
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