Nanotechnologies in Construction: A Scientific Internet-Journal @nanobuild-en
Journal articles - Nanotechnologies in Construction: A Scientific Internet-Journal
All articles: 636
Scientific article
Introduction. Recent years have seen a pressing need to dispose of municipal solid waste due to rapid urbanization. The municipal solid waste incineration fly ash (MSWIFA) produced from solid waste incineration power plant exhibits pozzolanic properties and poses concern of toxicity leaching when used directly as building materials. This paper presents an alkali-activation method to produce sustainable alkali-activated MSWIFA materials (AAFMs) with various MSWIFA dosages and investigate the corresponding fabrication and performance. Materials and Methods. Composited alkali activators activate the MSWIFA with constant alkalinity of 5% and the molar ratio of Si/Na = 0.86. The resulting geopolymers' bulk densities, mineral composites, morphology, and compression strength are thoroughly examined. Results and discussions. Results show that the use of MSWIFA may lead to more loose structures because the bubbles are generated from metallic aluminum and alkali activators. Additionally, the production of multiple crystals also accounts for increasing porosity. The generated multi-crystals such as Sylvite, Halite, Hydrocalumite, Calcium Hydroxide, and Ettringite are further detected from the morphology and mineral analysis. Furthermore, compression tests and toxicity characteristic leaching procedures (TCLP) are conducted to investigate the mechanical performance and heavy metals solidification performance of AAFMs, with an optimal compression strength of 19.99MPa at 28 days for AAFM-10 while toxicity leaching is subject to regularity limits. Conclusions. This study shows that great potential of using the alkali-activation method to recycle hazardous municipal solid fly ash into construction materials with both ecological safety and high performance.
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Scientific article
Introduction. The use of bitumen microdispersed emulsion as a resource-saving method for road surface construction is a popular trend in the development of innovative nanostructures. The technological use of petroleum bitumen as a binder for road materials requires a reduction in rheological viscosity. This can be achieved through synergistic developments that involve the use of various additives and modifiers. Methods and materials. The composition of bitumen microheterogeneous emulsions includes: bitumen-containing raw materials (up to 70–80% of mass); water with hardness up to 6 mg-eq/l (from 20 to 30%); emulsifiers (up to 3%) and other components. For large-tonnage production of water- bitumen emulsions, a colloid mill is the most technologically advanced equipment. Results. Water-bitumen emulsions are formed as a result of two competing processes: crushing (dispersion) and coalescence (merging) of microdroplets of the bitumen dispersed phase. The microheterogeneous bitumen phase is distributed in the aqueous dispersion medium in the form of microdroplets ranging in size from 1 to 10 μm (the main share is made up of bitumen microdroplets with a diameter of 2–4.5 μm). The synergetic durable microstructure of asphalt concrete road surfaces, which is formed by supplementing interaction in the boundary layers of the bitumen binder with the surface of the mineral component, is determined by the dominant interaction of complementary factors. Discussion. The synergetic approach to extending the service life of asphalt concrete road surfaces by using bitumen microdispersed emulsions holds promise for interpreting their evolution. The road construction industry of the Russian Federation at the beginning of the 21st century is characterized by a large-scale revision of regulatory documents, regulating the requirements for the construction and operation of highways. Conclusion. The optimal solution to the current problems of intensive construction and reconstruction of Russian highways is the improvement of technological characteristics of road surfaces by adding bitumen microdispersed emulsions to the composition. In complementary strengthening of weak soils of the road surface of high-speed highways, the use of water-bitumen microdispersed emulsions is also recommended.
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Synthesis of an active substance for microcapsules in a polymer composite with a self-healing effect
Scientific article
Introduction. The aim of this study is to examine the properties of a synthesized epoxy resin hardener based on dicyclopentadiene and maleic anhydride. Materials and methods. The following chemical reagents were used for synthesis: dicyclopentadiene 98%, maleic anhydride (technical), trichloromethane (C.P.). The research was carried out with the Sintecor IR 10 FTIR spectrometer, the STA 449 F1 Jupiter thermogravimetric analyzer. Results and discussion. Studying the initial substances allowed the calculated and experimental data to be correlated. Subsequent operations then revealed the structure and thermal properties of the obtained adduct. Conclusion. As a result of this research, an epoxy resin hardener has been obtained that can withstand a wide range of temperature variations. The synthesized substance is expected to find practical application in self-healing polymer composites.
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Scientific article
Introduction. Currently, one can witness a boom of renewable energy in foreign countries: zones with earth, coastal and even offshore wind power plants are emerging, and the roofs of houses, hotels, schools and hospitals are being "dressed" by solar batteries and by panels to generate electricity and water. At the same time, despite the fact that these installations are unreliable and rare sources, many experts and politicians begin to mistakenly consider them as the basic ones. All that poses a scientific and technical problem of determining the place of nature-like technologies in the structure of life support systems of the population. Methods, models and tools. The paper analyzes the engineering systems of multi-apartment residential buildings and individual residential buildings that deliver life support resources (electricity, gas, cold and hot water, etc.). But one should also note that the engineering systems often keep potential fire-energy and environmental harm. To resolve the mentioned problems, some nanotechnologies and Russian patents concerning autonomous electricity, water, heat supply of individual residential buildings on them were proposed. Results and discussion. Modeling has shown that the combination of "Shukhovskaya" and vortex wind turbines with domestic hydraulic panels and solar panels makes it possible to create duplicated and tripled engineering systems of individual residential buildings, which, in terms of quality, reliability and safety parameters, are several orders of magnitude higher than the existing centralized resource supply systems for the residential sector of cities and rural settlements. Conclusion. The proposed approach makes it possible to determine the place of the so-called renewable energy in the structure of the resource supply system for cities and rural settlements, and it remains to assess its effectiveness, which is supposed to be done using the Leontiev-Ford model and the retro-forecasting method.
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Synthesis of self-healing microcapsules based on dicyclopentadiene
Scientific article
Introduction. The study aims to explore the possibility of creating microcapsules using a carbamide-formaldehyde shell (coat) that contains dicyclopentadiene. Materials and methods. The following reagents were used to synthesize carbamide-formaldehyde microcapsules: distilled water; carbamide (urea) with a purity of 99%; technical formalin; sodium hydroxide (Pro Analysis «PA»); neem seed oil (NSO); polysorbate Twin-80; dicyclopentadiene with a purity of 98%; absolute ethyl alcohol (dehydrated); hydrochloric acid (Pro Analysis «PA»). Results and discussion. Organic microcapsules were obtained by polymerization of carbamide-formaldehyde resin. Filling of microcapsules with dicyclopentadiene has been carried out by establishing equilibrium between concentrated solution of dicyclopentadiene in alcohol and capsule contents. Average size of capsules was ~100 μm. Capsules have spherical shape and solid shell. Fourier-transform IR (FTIR) spectrum confirmed required compositions of capsule shell and filler. Analysis of DSC curve (Differential scanning calorimetry curve) showed that filling of capsules with dicyclopentadiene was successful. Conclusion. The result of the research done is the successful synthesis of microcapsules using a carbamide-formaldehyde shell. This synthesis of microcapsules and its application in building materials technology opens up new prospects for creating composites with selfhealing properties.
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Techniques to lower carbon footprint in producing, transporting, and laying concrete mixtures
Scientific article
Introduction. The concentration of CO2 in the atmosphere over the past 70–80 years has been showing steady growth. A key contributor to this increase is the manufacturing of concrete building materials and structures, for which cement is the primary component. One of the advance solutions to reduce carbon dioxide emissions in the construction sector may be the use of modified concrete in structures. The purpose of this study is to analyze the processes of concrete mix production in terms of carbon dioxide emissions at each stage, as well as to select the composition of the modified concrete mix to reduce these emissions. Methods and Materials. The assessment of the carbon intensity of the components of the concrete mixture and the stages of its life cycle has been carried out. Processes related to CO2 emissions include production, transportation of raw materials and production of concrete mix. Results and Discussion. The data analysis demonstrates the dominant contribution of cement production to the total carbon footprint of raw materials. A comparative assessment of the carbon intensity of various formulations revealed a significant potential for the use of mineral additives to reduce it. A comprehensive analysis of the properties of modified concrete served as the basis for the development of a detailed technological scheme for its production. Conclusion. The partial replacement of Portland cement with carbon-inert materials such as fly ash, microsilicon and nanosilicon can significantly reduce the carbon footprint of the final product.
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Scientific article
Physico-chemical processes of structure formation in nanocomposite building materials are associated with transformations of binding matrices and reinforcing components. The efficiency of building composites in the designed structures depends on the accurate choice of the source components: nanobinders, fillers (aggregates) and manufacturing technology. Increased corrosion resistance of building materials is provided by optimal selection of nanobinders and fillers, by increased density and treatment of the structure surface with protective coatings. The manufacturing feasibilities for nanocomposites based on various raw materials, nanobinders (gypsum, cement, bitumen, polymer, etc.), and inclusion of various dispersed phases (nanofillers, natural and technogenic aggregates) expand the variety of building composite materials. The synergistic dynamism of the occurrence of geometrical regularity of nanostructures during the structure formation of binders correctly demonstrates the fractal concept. Fractal nanostructures of binders with a rough surface are formed according to mechanism of diffusion-limited aggregation.
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Technological equipment management for 3D additive printing of building nanocomposites
Scientific article
Introduction. The development of innovative approaches to digital equipment control that ensure the production of 3D building structures with high operational and technical-economic characteristics remains an urgent task. The handling and maintenance of technological equipment during the process of 3D-printing of construction objects do not always meet the modern requirements of technical systems management. Methods and materials. 3D-printing is based on the method of extrusion: molding of a building structure layer-by-layer with the addition and fairly rapid subsequent solidification of nanocomposite building materials. The resulting optimized nanocomposition must have the required rheology, which set the comb-like polycarboxylate esters with nanosteric repulsion at a distance of ≈ 11 nm. In order to organize a stable 3D-printing technology, it is also necessary to select the appropriate optimal fillers that provide the necessary physical, mechanical and operational characteristics to the hardened nanocomposite. Results. The effectiveness of three-dimensional printing calls for the coordinated operation of a construction-grade 3D-printer. In this regard, it is necessary to have concrete pumping equipment that is able to pump the initial nanocomposition through flexible pipelines at a certain speed. It is necessary to consider the influence of pressure and volume to increase the power of the concrete pump motor by 14–17%, and at the same tine reduce the level of vibrations. Discussion. Digital 3D-technologies reveal unique opportunities for innovative production of three-dimensional construction objects and engineering structures. Technological quality management of 3D-printing depends on the correct alignment of the printer mechanisms, and the reduction of defective products can be achieved by adjusting the molding parameters of building nanocomposites. The structure-forming curing of Portland cement nanocomposites is based on the formation of fractal structures of calcium hydrosilicate clusters with dimensions of 47–51 nm, that form nanoaggregates (125–132 nm), which gradually cement the fillers due to adhesive interactions. The high demand for the corresponding equipment only strengthens the advantages of 3D-additive technologies: its practical waste-free operation, low power consumption of 3D-printers, time reduction of design-to-completion process by 8–11 times. Conclusions. Technological managing of concrete pump equipment for 3D-additive printing of building nanocomposites reduces energy costs by 26–29%, and at the same time reduces the level of vibration.
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Technological innovation and the emergence of a new interdisciplinary field – Management Analytics
Scientific article
The Introduction argues that interdisciplinary research relies on shared knowledge. When knowledge is shared, a fundamental shift can occur over time, and a new interdisciplinary field can emerge. For example, nanoscience, quantum computation emerges as interdisciplinary fields that eventually grew to become their own disciplines. Main part. The article provides a review of extant papers on management analytics. The field of management analytics is a newly developing interdisciplinary field that is attracting more and more attention. In this study, overall, 201 papers were examined. The results show that that the field of management analytics is emerging. Two main aspects of the field are investigated: application-based research and theory-based research. This study aims at providing a status of the area called Management Analytics for academia and practitioners. Conclusion. This paper focuses on the emerging interdisciplinary field called Management Analytics, based on an analysis of 201 published articles on the subject. For the first time, this study provides a comprehensive literature review of the emerging field of management analytics. The developing trends, characteristics, and related applications are introduced.
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Scientific article
Introduction. The theoretical foundations and practical aspects of implementing technological justification for design concept of railway roadbed on permafrost soils using an expert system are considered. Railway construction in permafrost regions requires specific design solutions and technologies due to complex natural and climatic conditions, geological process dynamics, and the need to coordinate multiple project participants. In such conditions, the development of efficient technological processes, including the construction of railway roadbed, becomes crucial and is achieved through the implementation of an engineering-intelligent subsystem for technical support. The aim of this study is to develop a methodology that integrates intelligent technologies into the processes of designing railway roadbed on permafrost soils to achieve an optimal balance between timelines, cost, resources, and operational reliability of the structure. To this end, an analysis of the technological features of construction in the cryolithozone was conducted, including site-specific localization, resource intensity of processes, variability of design parameters, and year-round work operations. Methods and Materials. The methodology includes the decomposition of the railway roadbed into constructional elements using graph models that formalize the interconnections between subsystems, as well as the development of an expert system based on a production knowledge model for automating the generation of construction work nomenclature. The results of the decomposition and generation of construction work nomenclature form the basis for optimizing the technological process, scheduling, and the development of work production projects. Results and Discussion. Based on the results of the theoretical research, the article explores the possibilities of applying a specially developed experimental software module for the technological justification of design solutions for railway roadbed on permafrost soils. The practical significance of the study is confirmed by the implementation of experimental software modules, including those incorporating intelligent components. This enables a transition from traditional variant-based design to adaptive real-time solutions, minimizing errors and time expenditures. Conclusion. The results of the work demonstrate the potential of intelligent information systems for railway construction in permafrost regions, where process formalization and decision automation play a key role in achieving sustainable development in the industry.
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Scientific article
Introduction. Small innovative enterprises are able to solve the problems of technological support of the construction sector. A special place is occupied by enterprises created on the basis of the results of intellectual activity (RIA) of higher educational institutions. The activities of small companies created with the participation of universities have a number of advantages. The scientific and educational environment creates additional opportunities for small businesses in conducting research and development, as well as opens up access to human resources. An example of the commercialization of RIA is the technological developments based on nanomaterial of St Petersburg University enterprises in solving the problem of abandonment of orphan wells, which contribute to the pollution of groundwater. Methods and materials. Abandoned wells are abandoned according to “standard designs” that provide for the abandonment of only the wellbore limited by the inner diameter of the casing pipes, and do not contain technical solutions for the elimination of behind-the-casing flows. Results. An ownerless well, after its abandonment according to the “standard project”, continues to contaminate groundwater, but on a permanent basis, since repeated abandonment of such wells is practically impossible. Each such “abandoned” well is an officially created channel for groundwater contamination in the long term. Discussion. The article contains an analysis of the existing technology of abandonment of wells, including ownerless ones, as well as the justification of the futility of its use to eliminate sources of groundwater pollution. An alternative solution based on the use of modern nanomaterials is proposed. Conclusion. Examples of successful application of the proposed technology with the use of cemented nanomaterials for the liquidation of emergency wells in the North-West region are given. Based on the study, conclusions and recommendations are made.
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Technology of three-dimensional laser scanning as a tool to provide safety for sport facilities
Scientific article
Introduction. Human safety during sport activities depends mostly on the technical states of sport facilities. According to current legislation, every school and higher education institution with sport facilities must meet nationwide standards for safety requirements. Sports facilities with existing codes and GOSTR are inspected by a special committee, which is required for accreditation, and which has been applied for several decades. This study offers more accurate and up-to-date methods for inspection of these sport facilities, specifically three-dimensional laser scanning. The technology of three-dimensional laser scanning is used mainly to obtain high precision and detailed measurements of any object. The authors analyzed the methods of application of three-dimensional laser scanning to assure human safety during sport activities at schools and higher educational institutions. Materials and methods. The objects analyzed were running tracks at the stadium at Kuban State Technological University. The main research method is an empirical one, namely field measurements. Scanning of racetracks was performed with the Leica ScanStation C10 from six stations. After field measurements were taken, point cloud was imported into special software to process the results of the laser scanning by the Leica Cyclone. After measurements were taken, all the critical points of the racetracks were classified by the height. According to existing standards for racetracks at athletic stadiums, the allowable value of roughness is 10 mm. Results and discussion. Classification of points revealed that the limit value for roughness of University’s racetrack was 9 mm (which meets existing safety requirements for racetracks). Thus, racetracks of Kuban State Technological University underwent the accreditation process performed by the research group from the Department of Cadaster and Geo-Engineering. Conclusion. The conclusion of the paper detertmined that, in fact, laser scanning can be applied to control safety of race tracks.
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The application of calcium polysulfide to increase corrosion resistance of the timbering of wells
Scientific article
The cement slurries used in well casing should ensure the tightness of the lining and protect the casing from aggressive formation fluids. At the same time, cement and water based solutions are used for cementing, with a water-cement ratio of 0.45–0.9, which predetermines their high porosity and low corrosion resistance. The technologies for increasing the durability of concrete used in con-struction practice when fixing wells are not acceptable. One of the most aggressive components of reservoir fluids is hydrogen sulfide, depending on thermodynamic conditions, can be both dissolved and gaseous. The analysis of various types of corrosion of cement stone shows the ki-netics is determined by the diffusion of aggressive ions into the stone. To reduce the porosity of the cement stone, calcium polysulfide has been proposed, which can precipitate in the pores of the stone during hardening of the cement slurries, clogging the pores, reducing their size, slowing down the diffusion rate of aggressive ions into the cement stone. In addition, calcium polysulfide adsorbing in the pores on cement hardening products will ensure the inhibition of pore space. Three methods of calcium polysulfide injection into the cement slurries were tested: into the tempering fluid (water), directly into the prepared cement slurry and dry method, through cement powder, which was subsequently subjected to disintegrator treatment. The results of the experiments showed calcium polysulfide make an impact on the rheological properties and pumpability of cement slurries, increasing the strength of the obtained stone and reducing its permeability. The stability of a stone in an acidic environment was estimated by its corrosion by one molar hydrochloric acid. The depth of stone corrosion with increasing concentration of PSS decreased from 30 to 6 mm in 21 days. When testing the cement stone under the action of dissolved hydrogen sulfide for 45 days, it was shown that the increased concentration of calcium polysulfide from 0 to 5% reduced the corrosion depth from 5.0 to 0.3 mm, depending on the technology of adding the reagent. Micrographs of cement stone samples proved that calcium polysulfide, being distributed in the pore space, blocks the surface of the cement stone, limiting the contact of aggressive ions with hardening products.
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Scientific article
The extrudability and firm stability are the criteria rheological characteristics of building 3D printable mixtures. This paper presents the results of experimental studies of the rheological behaviour of fresh cement pastes as matrices for 3D printable mixtures. The squeezing test, with constant plate speed, has been used for determination plasticity of cement pastes as criteria of their extrudability. As a result, the typical rheological models of the fresh cement pastes have been identified. In addition, the value of plastic yield stress was evaluated as criteria for the extrusion process. The squeezing test, with constant strain rate, has been used for determination structural and plastic strength, plastic deformations as criteria for the ability of a 3D printable mixture to hold shape during multi-layer casting. It is shown that these properties are significantly controlled by the plasticizer and viscosity modifying additives as factors of changes of disperse system «cement + water» properties. It is established that electrolytes, nanodispersed adsorption-active inorganic modifying additives increase the plasticity of the fresh cement pastes. At the same time, the nanodispersed adsorption-active inorganic modifying additives develop plastic strength as criteria of firm stability. The introduction of inorganic polymers, inert to cement, improves the structural strength of fresh cement pastes but significantly reduces their plasticity. It is shown that the management of rheological behaviour of 3D printable mixtures should be based only by the complex using of chemical addi-tives such as electrolytes, plasticizers and nanodispersed inorganic viscosity modifying additives.
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