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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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Development of Public Spaces: the Impact of Metro Stations Construction on the Formation of the Structure of the Adjacent Territory

https://doi.org/10.58224/2618-7183-2023-6-5-5
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Аннотация
The article aims to study the development potential of local urban centers around the rapid transit system with due regard to the historical traditions of urban development and modern urban planning principles. To attain this end, the authors use a set of methods, including site analysis, data collection, classification, and project proposal development. The paper presents the tradition of forming a peripheral public space within the historical boundaries of the city. It is demonstrated that the current development of local public spaces based on peripheral rapid transit stations can be considered a continuation of this tradition at a new historical and technological stage. The authors select metro stations suitable for the formation of local urban centers. To determine the possibility of placing a pub-lic space in the vicinity of metro stations, calculations are made for territories included in forty-three metro zones of the peripheral part of the city and thirteen zones of the middle part of the city. Based on a group of indicators for the selected stations, the authors conduct an analysis and compile a table that characterizes the territories near each rapid transit station. As a result, the density and floor space index, passenger traffic per day, and the balance of the adjacent territory for each station were deter-mined. There are draft projects for the development of territories, layouts, and visualizations of the proposed options for building open public spaces. The authors consider scenarios for the placement and transformation of public centers near metro stations. The study reveals how the construction of each metro station affects the adjacent territory. It is worth mentioning that new stations affect not only the lifestyle of citizens, with improved transport accessibility, the status of the territory increases, new centers of social activity, and new public spaces emerge.
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National Artistic Traditions in the Formation of a Model of Architectural Development of City Limits

https://doi.org/10.58224/2618-7183-2023-6-5-6
Аннотация
The study considers the planning of Russian estates from both architectural and social perspectives, as well as their influence on the modern construction of urban outskirts, which is necessary for the development of city limits. The article examines the planning and organization of socio-cultural space as exemplified by the Russian estate at the turn of the 18th and 19th centuries. By analyzing the architectural complexes of the Russian estate and developing surroundings in this period, the authors propose a model for organizing the socio-cultural space of city limits. The article dwells on the historical architectural ensembles of Arkhangelskoye and Abramtsevo, as well as various types of Russian estates, whose territories are being developed as city outskirts. The study considers modern opinions and assessments of planning territories bordering historical architectural monuments through various research methods. The obtained results allow the authors to develop a model of a socially sustainable architectural ensemble, including its socio-cultural, artistic, and educational functions.
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Recycling of Municipal Solid Waste in Construction

https://doi.org/10.58224/2618-7183-2023-6-5-7
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Аннотация
This article discusses a promising direction focused on the use of recycled municipal solid waste in construction. In Russia, there are problems related to municipal solid waste management, which necessitates the modernization of this process and confirms the relevance of the issues raised. Analysis and use of the experience of foreign countries in the processing of municipal solid waste and its secondary use in Russia contributes to the search for a more environmentally responsible approach that entails both economic and social benefits. The use of solid municipal waste recycling products in construction is aimed at minimizing the negative impact on the environment and is a step towards the transition to a circular economy, where waste is turned into valuable resources.
The article reflects on the various methods of recycling municipal waste and analyzes the priority areas for the processing of municipal solid waste. In addition, examples of successful building projects using recycled products are given, and the challenges and prospects of this approach, as well as its significance for sustainable development and environmental responsibility in the construction industry, are revealed.
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Circumpolar Aspect in the Development of Urban Environment Organization in Russian Cities

https://doi.org/10.58224/2618-7183-2023-6-5-8
Аннотация
The purpose of the paper is to examine the effect of the Arctic Hectare program on the development of Russian cities in the Arctic region. In particular, the study analyzes the role of the program in changing the borders of settlements and the possibility of their regulation. The research employs a qualitative approach, including the collection of data from government documents, research literature, and electronic resources associated with urban development, regional development, and the Arctic Hectare program. Data analysis shows that most Arctic cities continue to compress: with preserved infrastructure, entire houses and areas of settlements go empty. In contrast, the Gulf of Ob shows an increase in settlements, as its mining areas actively expand. The area demonstrates a principle characteristic of circumpolar urban development, e.g., a fractal system of settlement growth with the development of the next branch of the city tree. The restart of empty suburbs outside the zone of active mining is attributed to the stage program of Arctic Hectare. As a result, the authors identify two concepts of urban planning: one that emphasizes development along outbound highways, and another that assumes the development of satellite cities. In the near future, the familiar urban landscape may change, as its outskirts may be supplemented by low-rise development. A large share of applicants use the Arctic Hectare to solve the housing problem. It becomes clear that the suburbs are a realistic way of habitation in the Arctic region. The researchers argue that the sustainability theory can allow pre-dicting urban development in the territory based on adaptive cycles.
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Влияние плазменной обработки высокочастотным индукционным разрядом пониженного давления на повышение адгезионных характеристик стекловолокна

https://doi.org/10.58224/2618-7183-2023-6-4-5-14
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 5-14 стр.
Аннотация
В статье приведены результаты исследований, подтверждающие преимущества плазменной обработки при производстве стеклонаполненных композиционных материалов на основе полиамидов, заключающиеся в экологичности, ресурсосбережении и отсутствии зависимости от химических растворов, которые предлагает плазменная обработка по сравнению с традиционными методами. Путем оптимизации параметров обработки в исследовании также изучается, как плазменная обработка может управлять характеристиками поверхностного слоя и структурой материала, чтобы улучшать определенные характеристики стекловолокна без ущерба для других свойств.
В рамках исследования проводились эксперименты по изучению влияния низкоэнергетических ионов, генерируемых высокочастотной плазмой, на технологические характеристики стеклян-ных волокон. Предыдущие исследования показали, что плазменная обработка в различных га-зовых средах (аргон, воздух, пропан-бутановая смесь) позволяет удалять замасливатель с по-верхности стекловолокна, активировать его поверхность, увеличивать адгезию в системе поли-мер-наполнитель.
Для оценки адгезионных характеристик обработанных плазмой стеклянных волокон были про-ведены тесты на капиллярность. Результаты показали прямую зависимость между увеличением показателя капиллярности, длительностью и интенсивностью плазменной обработки. В резуль-тате исследования были определены оптимальные параметры обработки для достижения жела-емых адгезионных характеристик, в результате чего адгезионная прочность увеличилась в 1,5-1,7 раза.
Результаты исследования подтвердили сохранение эффекта плазменной обработки во времени, в связи с чем, рекомендуется использовать модифицированные стекловолокна для армирования полимерных матриц в течение первых 10-25 дней после обработки.
Полученные данные позволяют рекомендовать плазменную обработку для модификации стек-лянных волокон при производстве армированных полимерных композитов.
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Инъекционные растворы на композиционных цементах для закрепления грунтов

https://doi.org/10.58224/2618-7183-2023-6-4-15-29
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 15-29 стр.
Аннотация
Закрепление просадочных грунтов является важной практической научно-технической задачей, позволяющей осуществлять строительные и ремонтные работы на слабых (просадочных) грунтах оснований. Разработаны композиционные цементы (КЦ), включающие алюмосиликаты (АС), полученные обогащением золошлаковой смеси (до 65 мас. %), портландцементный клинкер и гипс. На основе разработанных КЦ создана широкая номенклатура инъекционных растворов с водовяжущими отношениями от 1,0 до 2,0, включающих отсев гранитного щебня с модулей крупности 0,7. Разработанные инъекционные растворы способны эффективно закреплять грунты оснований подземных сооружений, обеспечивая прочность грунтобетонного массива до 25,6 МПа с модулем деформации 10,1 ГПа. По данным седиментационного анализа растворов видно, что эти материалы обладают процентом водоотделения от 22,5 при В/В=1 до 36,5% при В/В=2. При этом показатели вязкости этих материалов говорят о высокой проникающей способности, так как время истечения растворов через вискозиметр Марша для растворов ИР5 и ИР6 составляет 39 и 40 секунд при В/В=1,5 и В/В=2, соответственно. Эффект повышения плотности инъекционных растворов на композиционном цементе в возрасте 28 су-ток, был максимальным при дозировке АС 45% по массе, далее он снижался с ростом содержа-ния алюмосиликатной составляющей. Отмечаются высокие отношения значений прочностных свойств во вторые сутки к аналогичным показателям в марочном возрасте: для прочности при сжатии 0,24 (0,20-0,22 у бездобавочных клинкерных композиций), для прочности при изгибе 0,16 (0,15 у бездобавочных клинкерных составов; при этом при повышении содержания АС выше 45% это отношение снижается до 0,14). Высокая ранняя прочность позволяет эффектив-но применять инъекционные растворы для срочного закрепления грунтов в ходе ремонта под-земных сооружений.
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