Nanotechnologies in Construction: A Scientific Internet-Journal @nanobuild-en
Статьи журнала - Nanotechnologies in Construction: A Scientific Internet-Journal
Все статьи: 523
Effect of laser modification on composite films with nanodispersed SiO2
Статья научная
Introduction. This research is aimed at studying the effect of laser modification on composite films obtained on the basis of polyimide track (nuclear) membranes and filled with nanodispersed SiO2; to change their optical and structural properties. Materials and research methods. Polyimide track (nuclear) membranes were used as a polymer matrix. Track diameter is 200 nm, membrane thickness is 25 μm. The tracks were filled with nanosized SiO2 by hydrolysis of tetraethoxysilane in the presence of track membranes. For composite film surface modification, we used ytterbium pulsed fiber laser Minimarker 2-20 A4 PA. We studied the change in the surface microscopy of composite films, their optical density, IR-Fourier spectra and surface wettability depending on laser treatment. Results and discussion. The authors have found the possibility of creating a composite film based on a polyimide track (nuclear) membrane and nanodispersed SiO2 by hydrolysis of tetraethoxysilane in the presence of a membrane. It is shown with the energy dispersive analysis method that silicon oxide has completely filled the pore volume of the track membrane. Laser modification of the composite material surface (composite film) leads to an increase in the contact angle of wetting from θ = 66.75 ± 1.55° to θ = 101.52 ± 3.03°. Thus, the material acquires hydrophobic properties. Also, the laser films modification has a positive effect on the transmittance of the films, namely, this coefficient increases. The greatest change is observed in the infrared region of еmitted spectrum, the average increase in transmission is +70.48%. Conclusion. The obtained results of the study are of great importance for understanding the mechanisms of creating composite films with improved optical properties, which can later be used to create composite films with desired optical properties for various applications.
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Effect of nanofibrillar cellulose on the cement paste setting kinetics
Статья научная
Introduction. The study addresses the effect of nanofibrillar cellulose (NFC) on the setting process of cement paste during the first hours of gauging. A brief justification of the research topic relevance is given. It has been noted that the modification of cement materials by nanoscale additives has sparked significant scientific and practical interest in recent years. NFC has emerged as one such additive, and the potential impacts of its incorporation into cement systems are currently under active investigation. The study aims at investigating the effect of NFC on the cement paste setting kinetics during the first hours of gauging. Materials and methods. We present the materials used in the research and their characteristics, in particular, two types of cement characterized by the presence or absence of false setting, as well as cement paste compositions with different NFC consumption (from 0 to 0.24% of dry matter by weight of cement). The technique of measuring conditional viscosity in time with a laboratory rheometer and a special measuring system is described. Results. The results of cement paste tests are presented in the form of setting process diagrams. Discussion. The results obtained and experimental data are given. The complex character of NFC influence on the cement paste setting kinetics has been noted, which depends on the cement quality and additive consumption. For cement without signs of false setting, a decrease in setting onset time was observed when increasing the NFC content. Conversely, increase in the amount of NFC leads to an increase in the setting onset time for cements with signs of false setting. Conclusion. NFC has a noticeable effect on cement paste setting kinetics in the first 3 hours: it accelerates the process when using cement without false setting and slows down the setting when using cement with false setting.
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Статья научная
Introduction. In the article the use of powder elastomeric modifier capable of rapid breakdown into micro- and nanofragments upon contact with hot bitumen to improve the low-temperature properties of bitumen is presented. The indicators of resistance to cracking are determined by various methods and their dependence on the thermal history of the samples. Methods and Materials. At temperatures up to –36оC the oscillatory rheological tests (4-mm DSR test) of RTFO-aged samples of bitumen BND 60/90 and modified binder (MB) which contain the active powder of discretely devulcanized rubber (APDDR) produced by high-temperature shear-induced grinding from the crumb rubber of worn tires have been conducted. MB was prepared by mixing bitumen (3 min; 160оC and 600 rpm) with 12.5 wt.% APDDR. Results and Discussion. The effect of the test parameters on the rheological parameters has been studied. Structural transitions in bitumen and MB by methods of differential scanning calorimetry (DSC) and the cracking temperature of the same samples in static conditions in the ABCD test were detected. It is revealed: a decrease in the temperature of actual cracking of the MB sample compared to bitumen. Conclusion. It is shown that APDDR as a modifier affects the structure of bitumen and reduces the temperature sensitivity of bitumen to external influences.
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Effective gypsum compositions with the addition of underburned ash and slag mixtures
Статья научная
Introduction. Currently, research and development in the field of nanomaterials science is being conducted worldwide. The rationale for developing innovative energy-saving materials based on gypsum binders for buildings and structures with optimized carbon dioxide (CO2) emissions allows us to consider underburnt ash and slag mixtures as a promising technogenic product that allows us to comprehensively solve technological, economic and environmental problems in the construction industry. The study of the possibility of synthesizing promising mineral compositions based on underburnt products isolated from non-recyclable ash and slag mixtures (ASM) of coal-fired power plants ensures the development of a base of design and engineering solutions for buildings and facilities with rational energy consumption and optimized CO2 emissions using gypsum nanomaterials with unique properties. Materials and methods. In the study, technogenic carbon (underburning) was isolated from ash and slag mixtures by flotation enrichment using reagents (flotators). Results and discussions. The results of the study of energy-efficient gypsum composites based on a technogenic carbon modifier confirm its active participation in the processes of structure formation and crystallization of nanostructured building materials with high-tech characteristics. Conclusion. The research results obtained in the field of developing innovative, energy-efficient, cement-free building materials can contribute to an increase in the level of knowledge and the development of innovative approaches in construction materials science. These findings will be useful for subsequent implementation in the construction industry. The research topic is in line with the implementation of state programs, including the Strategy for Scientific and Technological Development of the Russian Federation.
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Статья научная
The use of concrete in building allows obtaining reliable and long-lasting operation of buildings, but such conditions require concrete with specified characteristics. Today hardly one can produce a concrete structural mix of high quality without any additives. To control actively the structure and properties of a concrete mix and concrete, along with chemical additives, mineral additives are used. The mineral additives are the powders of various mineral nature, obtained from natural or man-made raw materials: ground slag, rocks, etc. The article introduces the method of obtaining a mineral additive for a structural mix, in particularly for concrete. Qualitative characteristics of the additive obtained were studied as follows: the index of the degree of grinding to be equal to 1, standard consistency (normal density) – (180±5) mm with a mass ratio of «additive: water») – 100: 70, setting time – beginning 20 min, water absorption 0.27%, water content 9.65%, the proportion of insoluble residue in hydrochloric acid solution is 1.70%. Implementation of the additive in the concrete composition has shown that the quality of the product does not fall, and the actual strength is 250.7 kgf/cm2, which is slightly higher than the strength of the concrete sample without an additive. It was determined that the quality of concrete products with a mineral additive corresponds to GOST as follows: density 1775 kg/m3; mass humidity 0.3%; volume humidity 0.5%. The introduction of a structural mix will significantly improve the properties of a concrete structural mix and will also reduce the fuel resources consumption for production of the concrete structural mix, products and constructions of its basis.
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Статья научная
Introduction. The elaboration of foamed eco-friendly gypsum nanocomposites with low specific gravity, high thermal insulation, operational and technical and economic characteristics remains an urgent task. Controlled hardening of gypsum foam nanoassemblers using dry foaming agents is a promising direction in the technology of production of heat-insulating building materials. Methods and materials. The production of a foam gypsum composition was carried out in an ejector-turbulent mixer by mixing a gypsum nanobinder with functional foaming nanoadditives. Building gypsum G5 BII was used as a binder in the work; porization of gypsum compositions was carried out using an adsorbed foaming agent PBNS. Results. The transformation of liquid-phase foaming agents into solid-phase ones by binding water allows the production of gypsum foam compositions from dry mixtures, which gives high dosing accuracy, a good degree of homogenization of components and stable characteristics of foamed gypsum nanocompositions. In production conditions, a one-storey small-sized pavilion was built using a pilot 3D printer AMT S1160, in which vertical enclosing structures are filled with foamed heat-insulating nanostructured foam gypsum. Monolithic foam gypsum nanomaterial with a density of 300–400 kg/m3 was used for insulation and sound insulation of attic floors during the overhaul of the historic building of the Veterans Hospital in Ufa. Discussion. The elaboration of technology for obtaining foam gypsum from dry mixtures is based on the advantage of manufacturing and using thermal insulation nanocompositions, which allows for significant punctuality of dosing and stable characteristics of foam gypsum building materials. Surfactants have a significant effect on the kinetics of the structure formation of the foam gypsum nanocomposition and slow down the coalescence of air bubbles. Conclusions. Nanoporous foam gypsum concrete, obtained as a result of controlled hardening, with a density of 400 kg/m3 has a thermal conductivity of 0.12 W/(m•ºС) and a compressive strength of 1.4 MPa. The compressive strength of foamed foam gypsum using a dry foaming agent on sorbents is 17% higher than the strength of a heat-insulating nanomaterial prepared using traditional technology.
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Статья
Introduction. The most effective binding agents in wood-polymer composites based on polyvinyl chloride are carboncontaining nanostructures, which improve the electrical, physical-mechanical, rheological properties, as well as the structure and durability of the composites. Their main disadvantage is a high degree of particle aggregation, which makes it difficult to mix and process them in polymer compositions. In this regard, an urgent task is to search for such carbon nanomodifiers that would have a low degree of aggregation and low cost. Methods and materials. The paper studies the effectiveness of mechanically activated petroleum cokes as binding agents in building wood-polymer composites based on polyvinyl chloride. Mechanical activation leads to the functionalization of carbon particles of coke with the formation of oxygen-containing groups on the surface. The effect of various amounts of coke (up to 10% of the mass of wood flour) is considered and the relationship between the nature of coke and their concentration in the polymer compositions with the main technological (melt flow) and operational (tensile and bending strength, high elasticity modulus, hardness, water absorption and thermal stability) indicators and supramolecular structure of woodpolymer composites has been identified. Results and discussion. With the introduction of cokes, a high degree of orientation of the supramolecular structures of the composites in the direction of extrusion of the samples is observed, which leads to an increase in the breaking strength and bending strength, as well as the high elasticity modulus. The optimal concentration of additives was determined from 0.1 to 5%. In relation to wood flour, the amount of which in the wood-polymer composition is 50 mass parts per 100 mass parts PVC. Conclusion. The introduction of mechanically activated petroleum cokes as binding agents in wood-polymer composites based on polyvinyl chloride has been carried out. Mechanical activation made it possible to reduce the aggregation of coke particles into larger agglomerates, which makes it possible to efficiently introduce the nanomodifier in dry form and to exclude the introduction of nanomodifier in the form of aqueous dispersions, which is a rather energy-intensive production operation.
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Статья научная
Introduction. In the context of the need to improve energy efficiency and decarbonize cement production, the development of technologies using natural active mineral additives is becoming increasingly relevant. This article examines the use of opoka and diatomite as active additives for producing Portland cement, which allows the clinker content to be reduced by up to 50% while maintaining the operational properties of the cement. Methods and Materials. The research was conducted using electron microscopy, X-ray phase analysis, and energy-dispersive microanalysis. The study analyzed the composition of clinker from SAS-Tobe Technologies, gypsum from the Bagalin deposit, slags from the Novo-Dzhambul Phosphorus Plant, opoka from the Turkestan-Urangay deposit, and diatomite from the Utesai deposit. Physicochemical tests were carried out in the “SAPA” laboratories and at the LLP “SAS-Tobe Technologies” plant. Results and Discussion. The results of the study showed that the addition of opoka and diatomite in a quantity of 15% accelerates mineral formation processes due to the formation of a liquid clinker phase at lower temperatures. This reduces the firing temperature by 100–150 °C, leading to lower energy consumption and improved thermodynamic processes in clinker formation. Conclusion. The introduction of natural mineral additives in Portland cement production reduces clinker content by up to 50%, contributing to energy and resource savings without compromising cement quality. The research results confirm the potential of using opoka and diatomite for decarbonizing the cement industry and increasing its energy efficiency.
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Energy resource efficient designs of small-sized water circulating cooling devices
Статья научная
To use natural sources in rational way, plantsof continuous cooling of closed systems of recycling water supply are used. The paper presents designs of small-sized devices for recycling water cooling which are energy resource effective due to twisted motion of air flow, moving countercurrent to the cooled water. Heat and mass transfer is a nanotechnological process that occurs at the intermolecular level. Methods and materials. Countercurrent mini cooling towers are widely used in all industries, but there are some disadvantages, the main of which is the insufficient interaction time of the moving phases. Screw motion of air flow is created by the tangential supply of cooling air in the bottom part of cylindrical small-sized cooling tower. The rate of rotary motion decreases as air flow moves up in cooling towers, and vertical parameter of the rate – increases. Such scheme of the air flow motionmakes it possible to decrease average vertical parameter of the rate and to increase phases contact time. Laboratory research. To determine the technological and hydroaerothermal characteristics, as well as to estimate the efficiency of cooling recycled water, and to carry out mass-heat exchange at the intermolecular stagean experimental facility of small-sized cooling tower with twisted air flow has been developed. Conclusions. In accordance with the exponential law it is shown that the rotational component decreases at increasing height, and in accordance with the power law the vertical component increases component with the exponent ~1,79. It is determined that moisture content x and air temperature tv in the volume of the height of the sprinkler varies according to a power law, in particular for a screw cooling tower proportionally x ~ h0,83, tв ~ h1,25. It was determined that the coefficients of mass transfer βxv and heat transfer αv of a mini cooling tower with twisted air flow at the intermolecular level with equal irrigation densities are 20% higher than the coefficients of a mini cooling tower with counter-current flow. Also it has been determined experimentally a dependence of aerodynamics resistance coefficient of the twisted irrigator of the cooling tower on criterium Refor air flow, and it was determined that it decreases like Re–K2 as the exponent K2 varies in the range 0.114÷0.193 depending on the irrigation density.
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Epoxy composites modified with coal tar
Статья научная
Introduction. Despite significant progress in the creation of high quality polymer composites with a unique combination of key indicators, some issues in this area have not been fully studied. This paper presents the results of research on the structure of materials based on epoxy-coal binder and analysis of physical and mechanical properties at the microstructure level, which are influenced by various factors: the quantitative content of modifying additives and various fillers, the degree of particle dispersion, their size and shape. It has been revealed that nanoscale particles are one of the potential modifiers of the microstructure of composites. Materials and methods. As part of the experiment, composites were studied, in which ED-16 epoxy resin modified with coal tar was used as the main binder. Polyethylene polyamine served as a hardener. Reduction of viscosity and plasticization of compositions was achieved through the use of gasoline, acetone, turpentine, white spirit, dibutylphthalate, etc. Quartz sand, fine powders of brick, marble, glass, limestone, and in addition, Portland cement were used as fillers. Two nano additives were used: carbon black and carbon nanotubes. Standard techniques were used to reveal the mechanical characteristics. Physicochemical investigations were carried out by IR spectroscopy. Tests of samples for fungus resistance and fungicidal properties were carried out in accordance with the State Standard (SS) 9049-91. Results. The results of composite tests are presented in the form of spectrograms, graphical dependencies, and tabular data. Discussion. The results of analyzing the obtained experimental data are presented. The optimum content of polyethylene polyamine for curing of epoxy-coal compositions has been determined. The following has been established: the physical and mechanical properties of composites depend to a great extent on the nature of the solvent, and changes in wide ranges have been recorded. It has been determined that the properties of composite materials are seriously influenced by the dispersity and quantitative content of the filler. The expediency of nano-additives application in epoxy compositions has been revealed. In the course of the experiment the dependences of the change of chemical resistance and biological resistance of composites on the type and quantitative content of the modifying additive, on the nature of the filler were determined. Conclusions. Modified epoxy-coal composites with the use of multilevel fillers and additives have been developed. This makes it possible to increase the strength, increase the deformability and crack resistance of building materials composites for operation, which is very important under the influence of chemical and biological aggressive environment.
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Статья научная
Today technological communities often consider lack of funding and ideas for establishment of startups as the biggest hitch for launching and development of innovative startups for the moment. But that seems to be unsound as the statistics says that there are plenty of financial institutions, venture funds, business angel investors as well as incoming offers from startups showing that there is a host of ideas. One of the most significant tasks in the international technology community is the development of technology entrepreneurs who are able to approach the establishment of their technological startups insightfully. As a rule, such entrepreneurs launching startups are focused on the process of design and development of a unique device, software and other products which they find outstanding, and only after that such issues as: who needs this product and how this product is going to be built into the manufacturing chain are considered by them. A technology entrepreneur with strong technology skills should direct his efforts to the market and end user. In the USA, Israel, Canada and European countries, this function is performed by the inventor, developer, scientist. Therefore fostering of skills of technology entrepreneurship is a very significant factor which allows inventors, developers and scientists to get basic knowledge of entrepreneurial activities and realize their own ideas at early stages. We will try to answer the basic questions which allow scientists, developers, and engineers to build a successful business based on their own developments and research.
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Статья научная
Introduction. Creation of highly efficient photocatalysts for construction composites, which are characterized by increased activity and an extended spectral range of action, is a very important area of research. It is known that “core (substrate) – shell (photocatalyst)” compositions, where mineral raw materials of various genesis can act as carriers, are one of the most effective types of photocatalytic additives for cement systems. It is worth noting that for integrated assessment of the substrate efficiency, we need to obtain information on the composition and properties of raw materials used among which its chemical activity and structure-forming role in cement systems are of paramount importance. The purposes of this study are (1) to establish the influence pattern of four types of mineral additives (silica fume, metakaolin, expanding sulfoaluminate modifier and microcalcite) on the structure formation processes of plasticized cement systems and (2) to identify the most effective modifiers for further use as mineral substrates in the photocatalytic compositions. Methods and materials. Specific surface area and granulometric composition of mineral modifiers were determined by the Kozeny-Karman and laser diffraction methods. The phase composition of mineral additives and modified cement systems were studied using X-ray diffraction phase analysis. Results and discussion. Features of mineralogical and granulometric compositions of mineral additives were revealed. It was determined that the use of individual and complex mineral additives based on silica fume, metakaolin and ESAM made it possible to directionally influence on content of the main phases of cement stone such as ettringite, portlandite, calcium hydrosilicates of different basicity. Conclusions. The increased chemical activity of these modifiers in cement systems, due to presence of reactive minerals in the structure, along with features of the granulometric composition (high dispersity and narrow particle size distribution), indicated the potential prospects for their use as mineral substrate in “core – shell” photocatalytic compositions.
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Статья научная
Introduction. The economic activity of a person entails environmental, economic and social damage to the environment. The production of goods or services is associated with the consumption of natural resources and emissions that negatively affect the ecological state. Currently, there is an acute problem of the negative impact of man on the natural environment and is the main source of deterioration in the health of living beings. In modern conditions, chemical safety is one of the priority tasks of socio-economic development. To protect the environment, it is important to take appropriate measures and develop appropriate mechanisms to promote sustainable development. For this purpose, an assessment of the environmental and economic damage from human activities is required. Materials and methods. The work employs the method for determining the prevented environmental damage, approved by the Chairman of the State Committee of the Russian Federation for Environmental Protection, to perform ecological and economic assessment of the environmental impact of new environmentally friendly biodegradable additives for polyvinyl chloride based on adipic acid. Results and discussion. Polymeric materials, as the most popular and widespread, make a significant contribution to the deterioration of the environmental situation. In this regard, the main values of the prevented environmental damage from soil degradation were calculated when using new environmentally friendly additives for PVC based on adipic acid. Conclusion. The introduction of the developed additives into the composition of the developed additives provides economic and environmental efficiency in order to accelerate the biodegradation of polymer composite materials, protects against chemical pollution by hazardous toxic compounds and helps prevent soil degradation.
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Статья научная
Introduction. Mineral wool is one of the widely used materials in the construction industry. A wide range of technologies and structures with integrated mineral wool is also connected with the following: ventilated facades of buildings, facades made using FICS (facade insulation composite system) technology, insulation of roofs and attics, and much more. Methods and materials. Under different conditions, the nanostructure durability for mineral wool fibers will vary significantly. Currently, there are no scientifically based methods for assessing the durability of the nanostructure. Results. The article proposes to evaluate the nanostructure durability for the of mineral wool fibers based on the developed method of chemical destruction of building ceramics. The methods of laboratory analysis of the building ceramics material and their modernization for the nanostructure of mineral wool fibers are given. Discussion. According to the results of experimental studies, it was found that the corrosion process in the mineral wool material occurs by the mechanism of reaction of alkali metal hydroxides with silicon and aluminum oxides in the mineral wool material, removing them into solution and leading to chemical destruction of the material, which is generally similar to the studied process of destruction of the wall ceramics material. The results obtained allow us to conclude that the process of chemical destruction of mineral wool has a greater dependence on temperature and less dependence on the concentration of hydroxides than the process of destruction of brick material. Conclusions. The results of the conducted studies allow us to calculate the temperature coefficient of the destruction process rate in the Van't-Hoff formula, the coefficients in the Arrhenius equation and the value of the activation energy of the destruction process. Examples of field studies are given.
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Статья научная
Introduction. An important performance characteristic of many building materials is one related to water. Therefore, hydrophobization of the surface of the material is an important task, which at the current level is solved by applying special means. It has been found that it is possible to impart water repellent properties to the surface by using polydisperse mineral materials capable of forming a rough surface. Fine powder from polymineral sand is proposed to be used as a hydrophobisate. The revealed functional relationship between the specific surface and the value of the average particle diameter of the powders, having a linear character, allows assessing their morphological structure and predicting the powder's ability to form a rough layer that enhances the water repellent properties of the surface. Methods and Materials. Four deposits of polymineral construction sands are selected as raw materials. The samples were washed and dried. Then their size modulus and true density were determined. To obtain finely dispersed powders, the raw material was ground by dry dispersion. Particle dimensional characteristics were determined by photon-correlation spectroscopy. The visual characteristic of the shape and size of the particles is determined on a laser analyzer. The specific surface area of highly dispersed rock systems was determined by gas sorption, according to BET theory. Measurement of the edge stationary wetting angle was carried out by applying a drop of distilled water to the powder surface. Results and Discussion. The dimensional characteristics of the obtained fractions showed that with a milling time (30 min) for the sands of all deposits, the average particle size (d) is 360±45 nm. At the same time, the sands of the Kenitsy and Nekhtskoye deposits have the highest values of specific surface area (Ssp). The functional relationship between the Ssp of the powders tested and 1/d was determined. The resulting linear dependencies were characterized by mathematical expressions of the form Ssp = (a/d)+b, a where reflects the rate of change in the specific surface value as the average particle diameter of the samples changes; b – is the regression line shift associated with the asymmetric shape of the particles and the non-uniformity (roughness) of the surface. It has been found that as the value of b increases, the degree of inhomogeneity of the surface formed by these particles also increases. Determination of the edge wetting angle of the surface of the powders under study showed that as the grinding time increased, the wetting angle (surface hydrophobicity) increased. So, for the surface of the fine powder of the Nekhtskoye deposit, the wetting edge angle reaches a value (114о) close in magnitude to superhydrophobicity (120о). Conclusion. The experiments showed the validity of the proposed working hypothesis related to the possible assessment of surface hydrophobicity by the experimentally determined dependence of Ssp = f (1/d). This technique can be used to select mineral powders whose fine systems are capable of hydrophobizing (if necessary hydrophilizing) the surface of the material.
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