Nanotechnologies in Construction: A Scientific Internet-Journal

Number 4, 2021

213-221
Nanostructured foam ceramics for building purposes: production technology and applications

Authors: Sinitsin D.A., Shayakhmetov U.Sh., Rakhimova O.N., Khalikov R.M., Nedoseko I.V.

Abstract

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Introduction. Foam-ceramic heat-insulating building materials have the greatest stability of the demanded technological characteristics due to their unique physical and technical properties. Increasing the large-capacity production of nanostructured foam-ceramic products and developing educational programs for advanced training of process engineers remains an urgent task. Methods and materials. A technological method for manufacturing nanostructured foam ceramics is the method of direct foaming: ceramic foams are created by involving atmospheric air in a suspension. Further, the consolidated foams are carefully dried and sintered for 12 hours by heat treatment (950–1100оC) to obtain sufficiently high-strength foam ceramics for building purposes. The most important raw materials for the production of construction foam ceramics are clays, diatomites, siliceous minerals, zeolite rocks, etc., as well as ceramic and slag waste, and the like. Results. The technology of production of foam-ceramic materials for building purposes based on clay raw materials has been developed. As a result of physical and chemical transformations in the production cycle, including firing, uniformly closed micropores of foam ceramics with a diameter of up to 120 microns are formed, and the wall thickness varies from 1.8 microns to 6.3 microns. The compressive strength of the obtained nanostructured construction foam-ceramic products with an average density of 450–850 kg/m3 is 3–8 MPa, thermal conductivity is 0.12–0.15 W / (m●о C),frost resistance is at least 50 cycles. Discussion. In large-scale technological production, bubbles mass (three-phase foam) can be obtained by mixing nanostructured foam with a highly dispersed mineral powder. By controlled sintering, a dried foam mass is produced with the required technological characteristics due to the crystal bond of a solid-phase mullite based on cluster microparticles with dimensions of 15–200 nm, and the walls of micropores and nodal joints of nanostructured foam ceramics provide high mechanical strength, hydrophobicity and chemical resistance. Conclusions. Nanostructured foam ceramics for building purposes is sufficiently moisture-resistant, since it has a microstructure of closed ultramicropores; it is resistant to chemical and physical effects and therefore is the optimal thermal insulation material.

222-228
Evaluation of the possibility to use powders of polymineral silica-containing sands as a hydrophobizing coating

Authors: Morozova M.V., Ayzenshtadt A.M., Akulova M.V., Frolova M.A., Shamanina A.V.

Abstract

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Number of views: 130

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.

229-236
Compatibilization of polymer mixtures during processing of waste products from thermoplastics

Authors: Fomina N.N., Khozin V.G.

Abstract

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Number of views: 191

Introduction. The recycling of thermoplastic waste into building materials with a long-life cycle is a promising and technologically feasible disposal direction. It is advisable to develop the processing of mixed polymer waste. Thermoplastics are thermodynamically incompatible, and technological compatibility can be controlled at the melt stage by the introduction of compatibilizers and nanofillers, the formation of free radicals in the melt, and reaction compatibilization. Materials and methods. The work aimed to study the effect of a compatibilizer – an ethylene-vinyl acetate copolymer with grafted acrylate and epoxy groups on the properties of composites obtained from mixtures of polyethylene terephthalate and polypropylene waste. The polymer mixture was melted, filled with limestone flour (50–85 wt.%), the samples were pressed, and their physical and mechanical properties were investigated. Results and discussion, conclusions. Differential thermal analysis established the melt preparation temperature of 240о C, which is below the onset of thermal oxidative destruction of the compatibilizer. It was established that the optimal ratio of polyethylene terephthalate: polypropylene: compatibilizer as 70:25:5 wt.% provided the greatest improvement in the bending strength without compromising the compressive strength of filled composites; the optimal degree of filling was found to be 60–70%. The volume fractions of polymers in the mixture are comparable. Therefore, one can expect the formation of both the matrix structure of the composite and the interpenetrating networks type structures. In both cases, the compatibilizer is distributed along the interphase boundaries. Its effect on properties can be attributed to its plastic deformation in the interfacial layer and morphological changes in the structure of the polymer mixture. There is evidence of increased structure-sensitive properties, tensile and tensile strength, of polymer mixtures containing this compatibilizer. This fact indicates an increase in adhesion between polymer phases, which is difficult to explain only for physical reasons. Possible reactions between the functional groups of the compatibilizer and polyethylene terephthalate in the melt with epoxy ring opening were analyzed. An increased effect of compatibility was revealed; however, the actual effectiveness of the compatibilizer is difficult to assess. Additional mechanical tests are required as well as optimization of the melt temperature. It is also necessary to find a balance between activating the reaction compatibilization and minimizing destructive processes in polymers.

242-251
Inventions of scientists, engineers and specialists from different countries in the area of nanotechnologies. Part IV

Authors: Ivanov L.A., Xu L.D., Pisarenko Zh.V., Nguyen C.T., Muminova S.R.

Abstract

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Number of views: 167

: Introduction. Advanced technologies impress people’s imagination demonstrating the latest achievements (materials, methods, systems, technologies, devices etc.) that dramatically change the world. This, first of all, concerns nanotechnological inventions designed by scientists, engineers and specialists from different countries. Main part. The paper briefly reviews inventions made by scientists, engineers and specialists from different countries: Russia, USA, China, Belarus, Great Britain, Vietnam, Denmark, the Kyrgyz Republic. The application of the results of scientists’, engineers’ and specialists’ investigations, including inventions in the area of nanotechnology and nanomaterials allow achieving significant efficiency in construction, house and communal service, related sectors of economy. For example, the invention “A method to modify concrete with complex additive which includes hydrothermal nanoparticles SiO2 and multi-layer carbon nanotubes” refers to methods of modifying concrete by introducing combination of nanoparticles with high specific surface into concrete mixture and can be used in production of precast and monolithic parts and structures of buildings and facilities of different purpose. This method of nanomodifying concrete makes it possible to achieve increased mechanical characteristics of concrete: compressive strength (25–77% at the age of 28 days) and bending strength, resistance to damage, Young’s mod of elasticity and shearing modulus, density (up to 10%), accelerated hardening at the early age and rate of strength development, decreased water absorbtion ability and improved indicators of porous structure (pore size and pore differential size uniformity), decreased total capillary porosity, increased frost resistance. The specialists can also be interested in the following nanotechnological inventions: a method to obtain polycrystalline diamond films; phase change materials for building construction: an overview of nano-/microencapsulation, solar collector of transpiration type; a method to obtain composition for antimicrobic coating on the basis of silver sulphide associates with molecules of methylene blue; broadband electromagnetic absorbing coating; a method to produce dry building mixtures; self-organizing nanostructures and separation membrane including aquaporin water channels and the methods to produce and use them; a method to obtain nanocrystalline titanium dioxide with anatase structure, etc. Conclusion. One of the most challenging tasks the economy of every country face is to increase industrial competitiveness through technological upgrade. From the side of the state and companies the principal object to control in this process are the people and enterprises dealing with introduction of inventions and new technologies.

252-258
Development of an intelligent control system for the process of preparation and water transfer in the cooling circuit of an ammonia station

Authors: Muravyova E.A., Kochenkov A.V.

Abstract

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Number of views: 119

: Introduction. In the modern socio-economic and geopolitical development of Russia, the development of industry comes to the fore. Among the many industries, ammonia stations play the most important role. The main regularities of the process of pumping and preparing water. The process consists of six stages, this article discusses the automation of stages 1 and 2: for water treatment and pumping it out with pumps H1 and H2 from the tank P2. Products in the form of purified water are the most important criteria for subsequent production at an ammonia plant, therefore, increased requirements are imposed on the quality of finished products, including the quality of purification of the water used with the help of nanofilters. The required quality cannot be achieved without control the process in an automated mode. Development of a neural network. To control the converters frequency values during the preparation and pumping of water, an artificial neural network must be used. Its development was carried out in the Matlab environment in the Neural Network Toolbox package, input and output data were defined for this, data processing and preparation were performed, as well as the choice of the type and architecture of the neural network. The architecture of the Layer Recurrent neural network, the process of its construction and training in Matlab is described. Testing of neural networks. During testing of the Layer Recurrent network for the degree of their training, the smallest error was obtained for 30 neurons in the hidden layer. The proximity to the set values indicates the applicability of the network for controlling the parameters of frequency converters. Development of the neural network controller model in the Simulink package. The simulation of the control system in the Simulink package using a neural network controller with the Layer Recurrent architecture is performed. Checking the frequencies of the frequency converters H1 and H2 in Simulink for the level parameters in the tanks and in the tank LT1_вх, LT2_вх, LT3_вх showed that the object model works correctly, thus, the simulation of the neural network showed that the training was successful. Conclusion. As a result of the conducted research, an artificial neural network was developed to control the process of preparing and pumping water in the Matlab environment and a simulation of a neural network in the Simulink package.

259-263
Technology of three-dimensional laser scanning as a tool to provide safety for sport facilities

Authors: : Gura D.A., Bespyatchuk D.A., Samarin S.V., Kiryunikova N.M., Lesovaya E.D.

Abstract

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Number of views: 140

: 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.