Nanotechnologies in Construction: A Scientific Internet-Journal

6-11

Authors: Pukharenko Yu.V., Khrenov G.M., Tkachenko V.I.

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.

22-31

Authors: Kozhevnikova O.V., Bokova E.S., Dedov A.V., Nazarov V.G., Ivanov L.A.

Introduction. The objective of this study is to examine the impact of the impregnation (with the aliphatic polyurethane water dispersion) degree on the deformation properties of the polyacetal, polyethylene terephthalate and polypropylene fibers based nonwoven needle-punched composite fabrics. Materials and methods. We investigated the deformation properties of the nonwoven fabrics manufactured from the 0.33 tex linear density fibers of: polyethyleneterephthalate (diameter 20–25 microns, according to TU 6-13-0204077-95-91), polypropylene (diameter 27–30 microns, according to TU 2272-007-5766624-93) and the original polyacetal ones (diameter 18–22 microns). The nonwoven fabrics were obtained by the mechanical formation technique. The needlepunching surface density was 180 cm–2. The water dispersion of anionic stabilized aliphatic polyethyruretane (IMPRANIL DL 1380 (China)) with a dry residue of 40% was used for the impregnation. The experimental samples’ linear dimensions were determined in accordance with the requirements of GOST 15902.2-2003. The sample’s thickness was determined by a thickness gauge with a pressure of 10 kPa and an instrumental error ~ 0.01 mm according to GOST 11358-70. The samples’ mechanical properties were determined in accordance with the requirements of GOST 15902.3-79. Results and discussion. The fiber filler composition influence on the ob-tained (by the impregnation of polyethyleneterephthalate, polypropylene and polyacetal fibers based non-woven needle-punched fabrics with polyurethane aqueous dispersion) composite materials tensile resistance has been established. We found the impregnation degree (depending on the chemical nature of the fibers and on the direction of nonwoven fabrics formation) at which the tensile resistance of the composite materials reaches the maximum value. It is demonstrated that, in the construction of buildings and structures, it is advisable to utilize materials based on composite polyacetal fibers. These materials exhibit higher tensile resistance compared to those based on polypropylene and polyethylene terephthalate at equivalent impregnation levels. Conclusion. The obtained optimal impregnation degree (at which the maximum tensile resistance of polyacetal fiber based composite materials was achieved) depends on the direction of the non-woven fabric formation. The maximum tensile resistance was observed: in the transverse direction – at 0.44 and in the longitudinal direction – at 0.35 impregnation degree values

50-58

Authors: Graneva A.V., Lushin K.I., Pulyaev I.S., Kudryavtseva V.D.

Introduction. In the process of demolition and dismantling of emergency buildings, as well as during construction and reconstruction, more than 70 million tons of construction waste are generated annually in Russia. The circular economy is based on the principle of resource renewal, recycling of secondary raw materials, technological measures to return waste to the repeated economic turnover. Nowadays the problem of saving natural resources and reducing construction waste is especially urgent. About 80% of construction waste is heavy and light reinforced concrete, from which can be produced secondary crushed stone, increasing the use of which is one of the tasks in the transition of linear economy to a circular economy. Materials and methods. The study of the implementation of a set of organizational, economic and technological solutions aimed at the reuse of construction waste was carried out. The analysis was carried out on the example of using secondary aggregates obtained from concrete scrap. Results and discussions. In the course of the research the necessity of concrete scrap involvement into repeated economic turnover was proved, as its use in construction fully meets the requirements of the set tasks in the field of energy and resource saving and environmental safety. Conclusion. Recycled crushed stone is a valuable resource that contributes to the sustainable development of the economy as a whole and reduces the harmful impact of the construction industry on the environment.

519-530

Authors: Kovalenko Y.F., Shulaeva E.A., Shulaev N.S.

ABSTRACT: Introduction. The application of nanocomposites in various industries has increased in recent years due to their unique properties and performance characteristics. Enhancing the quality performance of nanocomposites presents a formidable challenge, primarily attributable to the intricate interactions among their constituent elements. This paper presents an overview of the methods used to analyze and calculate the quality performance of nanocomposites using PVC as the base material. Methods and materials. To calculate technological parameters that are not directly measurable, we conducted a thorough analysis of literature sources related to the specific process under consideration. Through this analysis, we established appropriate relationships between empirical data in accordance with the fundamental principles of thermodynamics and mass transfer processes. In the course of the research, the method of neural networks was applied in order to describe the process of vinyl chloride polymerization carried out by suspension method. To solve this problem, a cascade network with forward propagation of the signal and backward propagation of the error was applied. Network composition: in the hidden layer – ten sigmoid neurons, in the output layer – two linear neurons. Results and Discussion. Throughout this research, it was observed that the heat flux during polymerization exhibits temporal variation, contingent upon the concentration level of the initiator. Further the dependencies obtained can be used in controlling the flow rate of refrigerant into the reactor cooling jacket, to ensure that the entire process is isothermal. It was found that by varying the stirrer speed, it is possible to change the particle size and hence the molecular weight distribution of polyvinyl chloride. The developed neural network was tested. The obtained results have minimal error and are close to the real values, from which we can conclude that the network is trained correctly and the dependence between the data is found. Conclusion. Dependencies linking physicochemical parameters of the technological process with the design features of the apparatus have been established. To maintain the quality of PVC, in particular the appropriate molecular weight distribution, a neural network (a cascade network with direct signal propagation and reverse error propagation, consisting of ten sigmoidal neurons in the hidden layer and two linear neurons in the output layer) was developed in MATLAB environment. The network was trained on a sample and tested on test values, which showed that the network predicts the outcome of the process with minimal tolerable error, with other parameters unchanged.

543-551

Authors: Asfandiyarova L.R., Khakimova G.V., Ovsyannikova I.V., Matveeva A.Yu.

ABSTRACT: Introduction. The advantages of nano-modified composite materials for construction purposes based on polyvinyl chloride (PVC) include enhanced strength characteristics compared to other materials [1]. Composite nanomaterials based on plant resources are versatile materials, whose properties can be modified through additives and processing technology to obtain a wide range of products in various application areas, particularly in construction, decking, outdoor and garden furniture, siding, picket fences, packaging, pallets, and much more. The research aims to investigate the influence of different additives on the technological and operational properties of the resulting composite. Nano-modified composite materials based on PVC are superior to polyolefin composites in terms of stiffness and strength, have high light-resistance as well as resistance to many chemicals, and are comparatively inexpensive as raw materials [2]. Methods and materials. The research aims to determine the preparation of composite materials that provide a highly effective stabilizing system against thermal decomposition, which increase the flow properties of the polymer melt, reduce water sorption, and impart sufficiently high outdoor stability; therefore, products made from composite materials can be successfully used in the construction area. Results. Research results have shown that the use of nanostabilizers in the technology of producing building materials can ensure preservation and ageing quality of polymer composites. They also have application potential on industrial scale. Conclusion. Investigations carried out on the use of a number of nanostabilizers, give to construction composites higher color retention and therefore increase environmental resistance of material

564-573

Authors: Kabdushev A.A., Agzamov F.A., Manapbayev B.Zh., Moldamuratov Zh.N.

ABSTRACT: Introduction. The efficiency of oil and gas well construction depends largely on the stage of casing cementing and is completed by checking the quality of its fixing by various methods, most often by geophysical methods. The necessity of highquality cementing and ensuring the quality of technical conditions in the subsequent years of oil and gas well operation is the main task. Materials and methods. Microstructural features of cement slurries and cement stone were analyzed with advance methods. The essential technological properties were developed according to the requirements of GOST 1581-96 and API standards (API spec.10B). Class G cement (PCT-I-G) was used for all formulations. Polypropylene fiber and expanding additive СMA were used to increase impact resistance and to ensure tight contact with the confining surfaces of the obtained plugging stone. Microstructural analysis of the obtained cement stones and developed plugging mortars was carried out by X-ray diffraction (XRD) and scanning electron microscope (SEM). Results and discussion. The results of the study showed that the expanding additive in tandem with polypropylene fiber works effectively to ensure the integrity of the cement ring. Conclusion. Microstructural analysis of plugging stones showed a tight bond between polypropylene fiber and cement stone at a concentration of – 0.25%. The expanding additive is fully hydrated and the obtained cement stone has no expansion cracks at 7 days. The developed grouts with a water-cement ratio of 0.44 showed high compressive strength.

583-591

Authors: Rada A.O., Kuznetsov A.D., Akulov A.O., Kon’kov N.Yu.

ABSTRACT: Introduction. Existing automated construction inspection technologies do not allow the user to select the level of detail. At the same time, in the context of the use of nanotechnology, there is a growing need to expand the capabilities of monitoring and control of construction projects. The aim of the research is to develop, implement software, and validate a technology for controlling the speed and accuracy of constructing three-dimensional models from dense point clouds for automated monitoring of construction works. Materials and methods. The research is based on the methodology of non-binary data trees, including the method of constructing octant trees. An unmanned aerial vehicle with an aerial laser scanner, a ground-based scanning total station, and specialized software were used, including the web application “Management System for Monitoring Construction Works on Objects that have undergone state expertise” developed with the participation of the authors. Results and discussion. In the course of the study, a technology was developed and implemented in software that allows the user to select the required balance between accuracy, degree of detail of monitoring and control data for construction work and time costs and computing power requirements. The comparison is made between a construction project, presented in the form of a building information model, and a three-dimensional model of a real object, obtained from a dense point cloud. The degree of comparison accuracy is set by choosing the level of octrees used. By default, the web application uses level eight. However, in the early stages of construction, when the geometric parameters of a dense point cloud deviate significantly from the design boundaries, the ninth, tenth and other levels can be used. In this case, the accuracy and degree of detail increases. Positive and negative deviations are visualized in red and blue colors, respectively, which allows the user to monitor and control the progress of work at the site. Conclusions. The developed technology can be used by customers and other decision makers to control and monitor work.

397-407

Authors: Samchenko S.V., Kozlova I.V., Zemskova O.V., Dudareva M.O.

ABSTRACT: Introduction. The evolution of the construction industry in its current stage calls for the alteration of traditional building materials through the incorporation of nano- and fine-dispersed additives. These additions confer new, unique attributes to cement-based construction materials, enabling control over structure formation processes. Consequently, this allows for the creation of materials with specifically defined characteristics. Additives can be introduced into the cement composite during the joint grinding with clinker minerals, as a component of dry building mixture, or in the form of a suspension instead of mixing water. Therefore, it is essential to obtain fine particles suspensions resistant to aggregation and sedimentation. Thus, the purpose of this study is to obtain stabilized suspensions of bismuth titanate fine particles for cement systems and to study the properties of modified cement stone. Materials and methods. The purpose of this work was to establish the optimal concentration of polycarboxylate plasticizer in industrial water, necessary for the stabilization of fine bismuth titanate suspensions using surface tension and conductometric determination methods, the sedimentation stability of the obtained suspensions and the effect of ultrasonic exposure, as well as the physical and mechanical characteristics of cement stone modified with the obtained suspensions. Results and discussion. In order to establish the optimal concentration of the plasticizer necessary to obtain stable suspensions of bismuth titanate particles, the critical micelle concentration (CMC) for the plasticizer was determined with tap water as the dispersed medium. The CMC value was 1.3 g/l. If the concentration exceeds CMC, the process of micelle formation begins. In the micellar form, the plasticizer no longer provides stabilizing effect on the additive particles, therefore, the concentration of the plasticizer should be lower than the CMC. It was also found that ultrasound exposure increases the sedimentation stability of suspensions. The resulting stabilized suspensions were used instead of mixing water to obtain modified cement stone samples. There is an increase in the compressive strength of cement stone samples obtained after the introduction of fine bismuth titanate into the cement composite in the form of water suspensions stabilized by ultrasonic treatment with concentrations of 10, 30 and 50 g/l. The increase in compressive strength of modified samples compared to reference sample was from 24 to 33 MPa at first day age (by 13, 25 and 38% respectively), and from 80 to 93 MPa at 28 days age (by 4, 9 and 16%). Compressive strength of samples modified with bismuth titanate suspensions after ultrasonication compared to reference sample with plasticizer increased mostly at the first and third days age: from 29 to 42 MPa (by 31, 38 and 45%) and from 53 to 70 MPa (by 28, 30 and 32%) respectively. Conclusion. As a result of the research carried out in this study, the Critical Micelle Concentration (CMC) of a polycarboxylate plasticizer was determined, optimal for stabilizing fine-dispersed additive of bismuth titanate for cement systems, the effectiveness of ultrasonic treatment to achieve sedimentation stability of the obtained suspensions of the additive was confirmed, an increase in the strength characteristics of modified cement stone samples was established both in the initial hardening periods and at 28 days age. The results allow to consider a cement composite with fine bismuth titanate as a basis for obtaining building materials of new generation

418-423

Authors: Vakhitova R.I., Saracheva D.A., Kiyamov I.K., Sabitov L.S., Oleinik V.Iv.

ANNOTATION: Introduction. This article presents the outcomes of research investigations examining the impact of carbon nanotube additives on the phase composition of cement mortars employed in well cementing operations. The quality of work on cementing and ensuring the impermeability of the casing string is quite important in terms of ecological compliance. Research methods. To solve this problem, heavy concrete was modified with a carbon nanoadditive. For research, a cement stone obtained by normalmoisture curing was chosen. Cement mortar CEM III/A32.5H was mixed with tap water for curing, preliminarily stirring a suspension of carbon nanotubes in water solution, a mixture of a water repellent and a hyperplasticizer. To ensure a homogeneous and highly dispersed structure of this suspension, its constituent components were subjected to preliminary dispersion in an ultrasonic field. Results and their discussion. The optimal ratio of carbon nanotubes in the composition of the cement mortar was determined, which amounted to 0.005% of the mass of cement for single-walled carbon nanotubes and 0.0005% for multilayer ones. The process of influence of the selected modifiers on the hydration products and the phase composition of the cement mortar was studied. An additive of complex action, including single-layer carbon nanotubes, was dispersed into solutions of a mixture of hydrophobic and hydrophilic surfactants, which made it possible to increase the strength of cement mortars up to 55%. Conclusion. In terms of modification, single-walled carbon nanotubes are the most efficient

443-452

Authors: Kopanitsa N.O., Demyanenko О.V., Kulikova А.А., Buryanov А.F., Lukyanova N.A., Soloviev V.G.

ABSTRACT: Introduction. This research work investigates the combined influence of nano-sized silicon dioxide (nano-SiO2 ), carbon nanotubes and surfactants on the structural and technological characteristics of cement compositions. Materials and research methods. The paper reveals the findings of a study on the effects of various dispersion techniques of carbon nanotubes (CNT) in surfactants, such as mechanical dispersion, ultrasonic treatment, and a combined method. It considers the uniformity of CNT distribution within the plasticizer and within the cement system, along with their impacts on the physical and mechanical properties of cement stone and concrete. Differential thermal and electron microscopic analysis of aqueous dispersions of carbon nanotubes and hardened activated nanomodified cement stone was carried out. Results and discussion. It has been experimentally proven that mixing nanotubes in dry cement does not allow them to be evenly distributed throughout the volume of the mixture. When using carbon nanotubes, the maximum effect is achieved when they are introduced into aqueous dispersions of plasticizers. The percentage of plasticizer was 1%, CNT 0,1% per 1 liter of water. The most effective method of dispersing carbon nanotubes in a plasticizer is a combined one. The results obtained were used in the preparation of cement stone and concrete compositions. Conclusion. The results show that complex additives consisting of nano-SiO2 and aqueous dispersions of carbon nanotubes have a positive effect on the physical-mechanical and structural-technological properties of cement stone and concrete. Graphic dependencies are shown indicating the effectiveness of using complex additives in the production of cement composites

465-473

Authors: Pavlenko V.I., Gorodov A.I., Yastrebinsky R.N., Lebedev M.S., Kashibadze V.V.

ABSTRACT: Introduction. Silicon oxide film coatings have unique properties and are widely used in various industries, including construction. This paper presents the results on the preparation of polyalkylhydroxysiloxane liquid film in the presence of nanoscale particles of metallic bismuth. Methods and materials. Laser ablation method of metallic bismuth in aqueous medium was used to obtain bismuth nanoparticles. The surface of the target was treated with a laser beam at the workstation of an ytterbium pulsed fiber laser are discussed. The particle size and electrokinetic properties of colloidal bismuth sols were determined method by dynamic light scattering. After drying, Bi powder was added to polyalkylhydroxysiloxane liquid. Thin films cured under different heat treatment modes are applied to glass substrates by dipping. The resulting films were characterized by SEM, X-ray phase analysis, and FTIR spectroscopy. Results. In this work, the electrokinetic properties of colloidal bismuth sols are discussed. Laser ablation of a bismuth substrate leads to an increase in electrical conductivity and the appearance of a double electric layer in colloidal sols. The effect of the curing temperature on the properties of the coating is shown. It was found that the content of bismuth nanoparticles in the polyalkylhydroxysiloxane coating (3 wt.%) does not lead to the formation of crystalline phases. At the same time, he composition of the film and the mode of heat treatment affect the short-range order of molecular bonds. Increasing the content of bismuth nanoparticles in the coating of more than 10 wt.% leads to the appearance of microcrystalline phases of bismuth silicates in the system. Conclusion. The results obtained in the course of the study supplement the information about the production of bismuth nanoparticles by laser ablation and are of great importance in the practice of creating composite films.

482-493

Authors: Bashirov M.G., Bashirova E.M., Yusupova I.G., Akchurin D.Sh., Yulberdin R.T.

ABSTRACT: Introduction. Approximately 20% of accidents in buildings and structures are associated with the destruction of metal structures. Nanocoatings applied to metal structures significantly improve their operational properties, but at the same time make it difficult to use traditional non-destructive testing methods that require access to the surface of the base metal. The quality of the nanocoating is controlled during its formation. To prevent the destruction of metal structures, it is necessary to identify structural heterogeneities of the base metal in micro- and sub-micron sizes, which arise in areas of increased mechanical stress concentration and transform into macrodefects leading to structural failure. Methods and tools are required to non-destructively identify the stress-strain state and damage of the base metal structure through the layer of nanocoating. Electromagnetic-acoustical (EMA) transformation, is considered promising for solving this problem. Existing EMA tools do not fully utilize the potential of EMA conversion, have insufficient sensitivity and the lack of informativity. Methods and materials. For experimental research, we selected widely used in construction structures steels. Research was conducted on the interrelationship of structural alterations in standard samples of metals and the parameters of the electro-magnetic (EMA) transducer under static and cyclic loads. Results. Load diagrams of metal samples were obtained, with accompanying photographs of microstructure in control points, along with their frequency models derived through spectral analysis of the signal from EMA transducer. Discussion. Changes in the stress-strain state of the metal and accumulation of damage in its structure result in a complex interrelated set of changes in mechanical, acoustic, and electro-physical properties, all of which are reflected in the changes in the parameters of the frequency model. Conclusion. Based on the results of the conducted research, the use of a frequency model has been proposed as an integral parameter for identifying the stress-strain state and damage of metal in the equipment. The use of an artificial neural network for analyzing frequency model parameters simplifies the process of identifying the stress-strain state and damage of metal structures and increases its reliability

298-309

Authors: Kuzina V.V., Samchenko S.V., Kozlova I.V., Koshev A.N.

ABSTRACT: Introduction. The complexity and laboriousness of system studies of physical and chemical processes in the volume and at the interface of the porous medium determines the need to apply mathematical modeling. This allows not only to identify and study the determining physical and chemical processes in a porous medium, but also to solve the problems of optimization and optimal control of processes and regimes by selecting the most favorable conditions. Methods and Materials. The method of mathematical modeling is used to study the processes, including the creation of composite and nanocomposite materials, as well as the moistening and moisture absorption in porous materials. In this context, the porous material is treated as a pseudohomogeneous medium with averaged physical and technological parameters. Results. The mathematical models of physical and chemical processes in the porous medium have been developed, the boundary conditions have been formulated, physical and effective constants have been determined. The processes in porous medium during metallization of carbon-graphite fibrous material, moistening of compacted textile material by an air flow, and moisture absorption by porous construction materials have been studied. Discussion. The adequacy of mathematical models to real physical and chemical processes is discussed. The results of calculations obtained by modeling equations implemented in the form of computer computational algorithms and experiments are compared. Conclusions. The effectiveness of the method for studying physical-chemical processes in a porous medium and for calculating optimal values of technological parameters has been established.

319-327

Authors: Kurmangalieva A.I., Anikanova L.A., Kudyakov A.I., Steshenko A.B., Buryanov A.F., Lukyanova N.A., Inozemtsev A.S., Inozemtsev S.S.

ABSTRACT: Introduction. This article presents the results of the research works on formation of building gypsum plaster porous structure with the use of recovered anhydrite raw materials and chemical additives, and describes a method for production of wall materials. The relevance of this paper is stipulated by the need to expand the range and increase the manufacture of heat-insulating and structural-heat-insulating products based on gypsum binders and local mineral raw materials, as well as the development of technologies to ensure the production of gypsum materials with improved performance. The authors proposed certain methods for forming the porous structure of building gypsum plaster and improving its performance in terms of porosity and thermal conductivity through the use of modified recovered raw materials and chemical additives of calcium chloride and sodium carbonate. Materials and methods. The study of the effect of modifying additives on the properties of the mixture was carried out using gypsum paste of normal consistency (NC = 55%). The preparation of samples and testing were performed according to the methods specified in the national standards with the use of porous additives of calcium carbonate, fluoroanhydrite and chemical additives for the rheological properties of the mixture, average density and strength of the samples, the patterns and mechanism of the processes of gypsum stone structure formation were established. Results. The application of fluoroanhydrite modified in the disintegrator with an equimolar amount of calcium carbonate leads to a decrease in the average density of the samples to 40% with evenly distributed pores. The analysis of the microstructure of heat-insulating material samples with a density of 550 kg/m3 showed that the average diameter of micropores is 0.45 mm, while the thermal conductivity of samples with complex chemical additives has the thermal conductivity coefficient of 0.25 W/m°C, which is 30% lower than the thermal conductivity of samples without complex additives. Conclusions. The results obtained create the basis for using recovery raw materials and domestic modifying additives as a pore-forming agent, which allow regulating the structure of gypsum stone in order to produce effective wall materials.

342-348

Authors: Boev E.V., Kasyanova L.Z., Islamutdinova A.A., Aminova E.K.

ABSTRACT: Introduction. Currently, wood-polymer compositions (WPC) are widely used in the national economy and construction. The composition of WPC varies widely depending on the further purpose. Improving the binding quality in the wood-polymer system is one of the promising areas for enhancing operational characteristics. Organic and inorganic substrates nanostructured with individual substances, including metal particles, are used as binding components. In the petrochemical industry, most high-capacity productions use catalysts based on active carriers like heavy metals when developing targeted products for various purposes. After several stages of regeneration, recovering these heavy metals becomes impossible. Consequently, spent catalysts accumulate in sedimentation tanks and sludge collectors, lacking an efficient method for disposal and secondary use. One of the components included in the composition of spent catalysts is chromium (+6), which belongs to carcinogenic metals. Numerous disposal methods are currently inadequate for neutralizing this metal on an industrial scale, which is of interest for research. Methods and materials. The study is aimed at converting carcinogenic chromium (+6) into non-carcinogenic chromium (+3) by ultrahigh frequency exposure (microwave), which will open up opportunities for its use as a chromium-containing nanocomplex binding a tree-polymer. Results and discussions. The ultrahigh-frequency effect on the mixture of wood-polymer composition and spent chromium (+6) causes an increase in the penetration depth of high–frequency waves, characterized by a uniform distribution of energy over the entire area of the composite, which is explained by the reduction of chromium (VI) oxide into chromium (III) oxide, and there is also a change in the color of the nanostructured wood-polymer composition (WP – compositions) from yellow to malachite. Conclusion. This study, which consists in the application of microwave exposure to the wood-nanoparticle-polymer system, confirms the receipt of a durable construction product and its use in the construction of roofs, facade boards, sidewalks, piers, port facilities, etc

359-372

Authors: Dorogaya E.S., Suleymanov R.R., Kuzina E.V., Yurkevich M.G., Bakhmet O.N.

ABSTRACT: Introduction. Currently a significant number of quarry restoration strategies have been developed, based on different aspects of soil impact: specifically, mixing the topsoil with the empty rock of exhausted quarries; introducing organic waste; applying mulching and polymer structure formers; using the adapted plants. In this study we attempt to combine the positive aspects of the previously mentioned methods. Therefore, the aim of our research is to create artificial soil-like structures with specified agroecological properties. We anticipate further use of the obtained mixture as a layer between the quarry waste material and fertile soil, which is to be applied to the reclaimed surface and followed by the planting of local plant species. Materials and methods. Studies on the possibility of reclamation of mine tailings were conducted under conditions of model experiment with sodium lignosulfonate (SL), a waste organic material from the pulp and paper industry, as the organic base for the soil-like body. Fine fraction soil (FS) sampled from the mine tailings was mixed with SL in ratios of 1/0.5, 1/1, and 1/2; to accelerate the decomposition of organic matter depending on the experimental scheme, strains of bacteria Acinetobacter calcoaceticus and Pseudomonas kunmingensis were added. The obtained mixtures have been composting for three months at a room temperature, with regular mixing and maintaining moisture levels. The phytotoxicity of the obtained mixtures was assessed by germinating seeds of a short duration radish variety called "18 days". Results and discussion. The application of sodium lignosulfonate (SL) into the fine fraction soil (FS) significantly increased the organic matter content and decreased the acidity of the medium. The fertilizing with nitrogen in the SL experimental variants has led to a significant increase in the content of alkali-hydrolysable nitrogen compared to the variants in the absence of N and the presence of SL. Conclusion. The research results showed that the application of sodium lignosulfonate (SL) to the fine fraction soil (FS) contributed to a decrease in acidity, an increase in organic matter and alkali-hydrolysable nitrogen content in the mixture, as well as a reduction in substrate toxicity

200-210

Authors: Beregovoy V.A., Snadin E.V., Inozemtsev A.S., Pilipenko A.S.

ABSTRACT: Introduction. The unique combination of rheotechnological properties and mechanical performance opens up prospects for the application of self-compacting and high-strength concretes in the manufacturing of base elements for machines and industrial equipment. The processes of adsorption of modern plasticizers on various mineral and polymeric modifiers of concrete mixtures were investigated. The compatibility of nano- and micro-scale mineral additives in composite cementitious binders was determined using calorimetry with an improved semi-adiabatic setup. Materials and methods. The cementitious binders used were CEM 52.5N Portland cement (Asia Cement LLC, Russia) and Nanodur (Germany, Dyckerhoff GmbH); hyperplasticizers included Melflux 1641F, 2651F, 5581F (Germany), PCE TR-6088 (China), Sika ViscoCrete 240 HE Plus and 226-P (Russia); superabsorbent polymer; nano- and micro-scale mineral additives included microsilica MK-85, metacaolin VMK-45, microcalcite MM-315, marshalite Silverbond 15 EW, and ground silica-containing rocks. Selective dissolution, differential thermal analysis, laser granulometry, and semi-adiabatic calorimetry were employed. Results and discussion. The quality of ultrafine mineral additives determines their ability to chemically bind portlandite through pozzolanic activity. Among the investigated additives, microsilica and gaize demonstrated the highest pozzolanic activity. Thermal activation was effective for components consisting of crystalline silica (marshalite, ground quartz sand), resulting in a 25% increase in performance. There was no selective adsorption of hyper plasticizer molecules by superabsorbent modifiers based on sodium polyacrylate compositions. Metakaolin and tremolite exhibited high adsorption to hyper plasticizers among the mineral additives. The rapid evaluation of the influence of formulation factors on the setting of cementitious composites was tested on an improved version of the semi-adiabatic calorimeter. Conclusions. The presence of micro-scale mineral additives based on microsilica in composite cementitious binders enables the development of high-performance concretes adapted for machine building. The study of pozzolanic activity, adsorption capacity, and cumulative heat release curves has indicated the feasibility of replacing microsilica with metacaolin and the potential for its partial blending with finely ground natural gaize. Analysis of the thermal effects accompanying the hydration processes of the "cement-additive-water" system with calorimeters allows us to provide more efficient research on the compatibility of additives in high-performance concrete compositions.

220-227

Authors: Zhegera K.V., Ryzhov A.D.,Sokolova J.A., Shestakov N.I.

ABSTRACT: Introduction. One of the reasons for coating destruction enclosing structures is the formation of condensate at the boundary of the fence and the finishing layer. As a result of external impact and freezing of moisture in the pores of the plaster coating, a network of small cracks is formed, and it is also possible to peel off the finishing layer. To test this hypothesis, the facades of three different buildings were examined. It is established that all the studied plaster coatings are made on the basis of cement mortar. It is also known that lime mixture is used less often due to the lack of sufficient resistance to moisture. Therefore, there is a need to increase the resistance of coatings based on lime compositions. This can be achieved by introducing an alumosilicate-based modifying additive into it. Materials and methods. Liquid sodium glass, aluminum powder PAP-1 and distilled water were used for the synthesis of the additive. Slaked lime (pushonka) with an activity of 84% was used to prepare test samples. Fritsch particle sizer Analysette 22 was used to analyze the granulometric composition of the additive. Compressive strength was determined on the samples measuring 20×20×20 mm. A testing machine of the type “IR 5057-50” was used for the study of compressive strength of samples. The analysis of rheological properties was determined by the Shvedov-Bingham equation. To study the plastic strength (ultimate shear stress) of the finishing mixture, a conical plastometer KP-3 was used. The plastic viscosity of the composition was determined with a rotary viscometer BCH – 3. Results and discussions. The synthesized additive is a light powder of light gray color with a bulk density of 0.55 ± 0.05 g/cm3. The synthesized additive revealed a high content of oxides Al2O3, SiO2, Na2O respectively, amounting to 51.03%, 36.36%, 11.89%. The additive consists of particles of 100.0–200.0 microns, which make up more than 20% of the total composition. The influence of an aluminosilicate additive on a lime binder on rheological properties was investigated, a slight increase in static shear stress was revealed, respectively, an increase in the percentage of the additive. The value of the dynamic shear stress increases significantly with an additive content of more than 10%. Conclusions. The regularities of hardening of a lime binder with a nanostructured additive based on amorphous aluminosilicates are established, and the optimal content of an aluminosilicate additive in the amount of 10% by weight of lime is determined.

238-245

Authors: Morozova М.V.

ABSTRACT: Introduction. The simplest and most common method of obtaining fine mineral powder is mechanical dispersion. In the process of grinding the material went through some work (energy), which is spent on the formation of a new surface. Therefore, it is not always clear whether the destruction of the crystal lattice of a solid lead to the activation of the resulting crushed material. Thus, the key characteristics of finely dispersed mineral powders, by which activation processes can be judged, are the value of the specific surface area (Ssp) and the specific free surface energy, numerically equal to the surface tension (σ) of the solid. Therefore, a number of models based on the determination of these characteristics have been proposed to estimate the mechanical activation process of the raw material. So, one of the most correct methods, in our opinion, is the method based on an energy approach to the evaluation of mechanical activation processes. This model determines the relative change in the free surface energy (ΔES/ES0) of the material when obtaining a dispersed system. At the same time, the choice of the most effective raw materials for obtaining composite binders can be carried out on the basis of the surface activity criterion (ks), which is used as a criterion characterizing the reactivity of fine mineral powders after their mechanical disintegration. Therefore, the aim of this study was to calculate the relative change in the surface energy of fine mineral powders of various raw materials and to identify possible functional relationship between the parameter ΔES/ES0 and the amount of surface activity for the studied rock systems. Methods and Materials. Sedimentary rocks formations the Arkhangelsk region were selected as materials for the research: polymineral sand and saponite-containing material (a representative of bentonite clays). Before conducting experiments, rock samples were brought to a constant mass at a temperature of 105о С. The chemical composition of the samples was determined on an X-ray fluorescence analyzer “Metexpert”. Highly dispersed rock fractions were obtained by dry grinding on a planetary ball mill Retsch PM100. The dimensional characteristics were determined using the DelsaNano submicron particle size analyzer by photon correlation spectroscopy. The specific surface area was determined by the gas permeability method on the PSX-10 device. To calculate the surface tension, the edge angle was measured on the “Easy Drop” installation. The surface tension for highly dispersed samples was calculated by the OWRK method. Results and Discussion. The calculated macro-energy characteristics of the studied samples have showed that the atomization energy for polymineral sand was 1910.72 kJ/mol, and for saponite–containing material was 1826.94 kJ/mol. At the same time, the mass specific atomization energy for sand and SCM are 30.41●103 kJ/kg and 26.94●103 kJ/kg, respectively. In the process of dispersion, several fractions of highly dispersed rock powders were obtained, which are characterized by an average particle size and specific surface area. The surface tension (and its components) calculated by the OWRK method showed that for all the samples studied, the polarization effect (σSP) prevails over the dispersion interaction (σSD). At the same time, as Ssp increases, the numerical value of the ratio σSP/σSD increases. This indicates an increase in the number of active surface centers associated with the redistribution of the energy potential of the system. The calculated values of free surface energy (ЕS), surface activity (ks) and the relative change in free surface energy showed, that ks and ΔES/ES0 increase as the duration of powder dispersion increases.The obtained functional dependences ks = f(ΔES/ES0) for the studied samples of polymineral sand and saponitecontaining material are linear in nature and obey the general equation у = a●x + b. In this case, the coefficient “a” characterizes the dynamics of changes in the reactivity of the material with an increase in the duration of mechanical grinding, and the parameter “b” – reactivity in the microstate. Comparison of the coefficients “a” of the studied dispersed systems showed that, unlike polymineral sand, the reactivity of saponitecontaining material increases 1.5 times faster as the grinding duration increases. The obtained functional relationship between the criteria used for evaluating the process of mechanical activation of mineral raw materials of various natures shows the correctness of the models used. Conclusion. The calculated macro-energy characteristics of rock samples showed that the atomization energy for polymineral sand and saponitecontaining material has similar values. To assess the effectiveness of the process of mechanical activation for mineral raw materials, it is proposed to use the relative change in free surface energy or surface activity. A functional relationship between above mentioned criteria has been established, which is characterized by a linear dependence

258-266

Authors: Poluektova V.A., Shapovalov N.A., Cherkashina N.I., Kozhanova E.P., Starchenko S.A.

ABSTRACT: Introduction. In the binary dispersed systems of different origins (mineral and polymer) with particles differing in size by an order of magnitude, heterocoagulation is observed. Regulation of the aggregate stability is crucial in controlling the properties of functional dispersed materials based on such mixed dispersions. This study focuses on the investigation of waterborne mono and binary dispersions of polyvinyl acetate, Portland cement, and chalk by means of static laser light scattering and optical microscopy. Materials and research methods. In order to investigate the action mechanism of the FF modifier based on phloroglucinol furfural oligomers as disperse phase we used chalk (CaCO3 – chalk dispersed technical MTD-2, LLC “Technostroy”, Kopanishchenskoe deposit), Portland cement CEM I 42.5N (JSC “Belgorod Cement”), and polyvinyl acetate (LLC “Kuban-Polymer”). Particle distribution and the aggregate stability of dispersions were studied with an Analysette 22 NanoTecplus device. The particle sizes were determined by optical microscopy with “Axio.Scope.A.1” microscope, and the adsorption of oligomers on the particles of dispersions was analyzed using a UV spectrometer (SPECORD UV). Results and discussion. It has been established that the phloroglucinol furfural modifier contributes to the stabilization of binary polymer-mineral dispersions. Integral and differential distribution curves of polymeric particles have been obtained in a wide range of 0.01–2100 µm. Research has shown the regularity of the modal diameter reduction of adsorption-modified particles with a transition from a narrow to a wider distribution with the absence of large coagulums. Conclusion. The hypothesis has been proposed that the adsorption-solvation factor of aggregate stability makes a significant contribution to the aggregate stability of binary polymer-mineral dispersions. The impact of this factor is different for mono-mineral and binary polymer-mineral dispersions and depends on the hydrophilicity of the surface, increases with the transition from mineral surface to the polymer surface as the Hamaker constant increases.

274-284

Authors: Denisova О.А.

ABSTRACT: Introduction. The use of liquid crystals is attractive for solving technical problems when creating a new generation of monitors, pressure sensors, seismic activity, determining the level of dry or liquid media, indicators of the concentration of harmful substances due to the small size of devices, low power consumption, simple design, low cost, and easy controllability of liquid crystals by various external fields. Under the action of mechanical shear, the liquid crystal layer is deformed, as a result of which surface polarization occurs. The purpose of the research is to conduct an experimental study of the effect of an electric field on flexopolarization occurring in a thin layer of a liquid crystal to create an acousto-optic shutter. Materials and methods. Nematic liquid crystals 10 – 100 µm thick with homeotropic orientation of molecules were used as materials: n – methoxybenzylidene n – butylaniline; 4 – octyl – 4 – cyanobiphenyl; nitrophenyloctyloxybenzoate; cyanophenyl ester of heptylbenzoic acid. Methods. The experimental setup consisted of a charge-sensitive amplifier with a high input resistance of 10 GΩ and a selective amplifier (2 MΩ). The design of the amplifier made it possible to apply a constant voltage of up to 100 V to its input, as well as linear and synchronous signal detections, which were then fed to the ADC that recorded them. Results and discussion. The behavior of charges induced on the surface of a liquid crystal due to internal mechanisms of molecular-orientation polarization was considered as a function of the magnitude and direction of the external electric field. For this, a liquid-crystal layer (MBBA) was placed in an electric field. The dependences of the first U1ω and second U2ω harmonics, when a positive potential is applied to a deformable plate, reach lower values than with a negative one. The electric field at a positive potential stabilizes the molecules of the polarized layer, and at a negative potential it makes it less stable, which leads in one case to a decrease in the slope angle on the surface, and in the other to an increase, which leads to an increase in the second harmonic. Under weak boundary conditions, a polar deformation occurs in the bulk of the NLC. When the field is applied to the homeotropic layer of NLC (CPEHBA), the value of the second harmonic U2ω increases linearly from the voltage Uc up to the achievement of “saturation”, which is due to an increase in the stabilizing dielectric moment over the viscoelastic one. At low fields (Е ≤ 104 V/cm), the value of U2ω first increases and then decreases due to an increase in the tilt angle of the director relative to the normal to the surface. At low polarizing voltages Uc ≤ 15 V (CPEHBA) dependence U1ω is approximated by a power function of the Uc3 type, at Uc >> 15 V the second harmonic U2ω depends as Uc–1. At low bias voltages, the position of the minima of the values of the first U1ω and second U2ω harmonics (for MBBA and CPEHBA) does not coincide with the zero point along the abscissa at Uc = 0. The harmonics U1ω and U2ω have a maximum when a positive potential is applied to the moving electrode. In the region of positive displacement voltages, the molecules stabilize, while at negative voltages, the molecules are less resistant to orientational perturbations. The value of the second harmonic U2ω sharply decreases with the perturbation frequency. Conclusion. The obtained research results can be used in the development of pressure sensors, seismic sensors for buildings and structures, light modulators, as well as an acoustooptic switch for glass units