Nanotechnologies in Construction: A Scientific Internet-Journal @nanobuild-en
Journal articles - Nanotechnologies in Construction: A Scientific Internet-Journal
All articles: 652
Scientific article
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.
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Development of armored products made from multilayer composite plates
Scientific article
Introduction. Modern requirements for personal and local armor protection dictate the creation of lightweight, durable, and efficient materials that can withstand a variety of threats, including shrapnel and low-velocity bullets. Conventional metal armor panels, while reliable, have a significant weight that limits their use. At the same time, ceramic materials, although they provide a high level of protection, are prone to the formation of secondary fragments upon impact. In this regard, composite materials such as aramid fibers and ultra-high-molecular-weight polyethylene (UHMWPE), which combine low weight with high strength and resistance to dynamic loads, are of particular interest. The article discusses the development of multilayer plates made from composite materials for personal and light armor protection. Methods and materials. Multilayer structures, including UHMWPE and aramid fabrics, were used to create armor plates. These structures were impregnated with epoxy resin and bioadditives such as collagen. The paper proposes a technology for the production of multilayer plates using aramid fabric and bioadditives. The technological process consisted of several steps: 1) a comprehensive study of the selected polymer materials with experimental determination of rigidity and strength characteristics; 2) cutting the fabric using a laser machine; 3) manufacturing an armor plate depending on the material and the loads subjected to it. Composite plates made from UHMWPE were created through hot molding using a press mold, and they consist of varying numbers of material layers. Multilayer elements (up to 30 layers) were made from aramid fabric with epoxy resin with bioadditives, which impart new elastoplastic properties to the material. Results. The ANSYS software package was used to calculate the strength of a multilayer composite plate under shock loading; field testing of the obtained plates as armor protection were also conducted, demonstrating good agreement with the calculations. Discussion. The obtained combined armor plates are highly effective in absorbing kinetic energy and preventing fragment penetration. Adding bioadditives to the epoxy matrix increased the interlayer defect zone, which contributed to the dissipation of impact energy. According to the authors, when adding bioadditives, the material acquires high fracture toughness. Conclusion (Findings). The developed armor plates offer a combination of low weight, no ricochets, and minimal deformation behind the barrier. This makes them promising for use in personal and local protective equipment. The use of bioadditives has improved the mechanical properties of the composite materials, and the test results confirm that the products comply with the Br3 protection grade, with a weight reduction of 25–30% compared to the analogues. The resulting products (low weight, absence of ricochet and traumatic consequences after impact) make them suitable for use as protection against shrapnel and pistol bullets.
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Development of artificial hydraulic lime
Scientific article
Introduction. Lime mortars used for the restoration of historical buildings are characterized by low resistance during operation. The durability of lime solutions can be increased by using hydraulic lime as a binder. However, the share of hydraulic lime in the lime binder production structure is only 19.8%. Given the low volume of production of natural hydraulic lime, it is promising to develop a formulation of artificial hydraulic lime. Materials and methods. To develop the formulation of artificial hydraulic lime, grade 2 slaked lime (pushonka) with an activity of 64% was used, as well as grade 2 air lime with an activity of 84% (GOST 9179-18). The technology for producing artificial hydraulic lime consisted of mixing slaked lime with pozzolan additives, as well as mixing air lime with pozzolan additives during the quenching process. When developing the formulation of the plaster mortar, quartz sand from various deposits was used as a fine filler. The optimal type of sand was selected based on the strength criterion of calcareous composites and sand activity, characterized by the value of free surface energy. Results. It has been established that the most effective is the addition of metakaolin. The compressive strength of the solution at the age of 28 days of hardening is 2.1 MPa when using second-grade quicklime. Increasing the dosage of metakaolin to 40% by weight of lime increases the compressive strength to 2.7–3.1 MPa. Pozzolan additives silica, dehydrated clay, diatomite at a dosage of 10% by weight of lime do not provide the required compressive strength of at least 2.0 MPa. The introduction of Portland cement in the formulation in an amount of 25% by weight of lime contributes to a significant increase in compressive strength, amounting to 2.9–4.0 MPa, depending on the type of additive and type of lime, as well as the technology of binder preparation. The porosity of calcareous stone based on artificial hydraulic lime was determined, amounting to 48–51%, while a decrease in the volume of closed pores was observed. Solutions based on artificial hydraulic lime provide sufficient adhesion strength to the brick substrate, amounting to 0.4–0.55 MPa/kg. It has been established that the use of methakaolin in the amount of 40–50% of the mass of air lime makes it possible to obtain artificial hydraulic lime. The developed compositions of artificial hydraulic lime are proposed to be used for the restoration of buildings of historical buildings, as well as finishing newly erected facilities. Conclusion. It has been established that the use of aerial quicklime in the preparation of artificial hydraulic lime promotes a more durable lime composite structure. The porosity of limestone based on artificial hydraulic lime is lower than that of limestone based on aerial lime, and for limestone based on cement-based compositions, it is lower than that of limestone based on hydraulic lime. HL artificial hydraulic lime and plaster mortar formulations based on it have been developed for the restoration of cultural heritage sites and the finishing of new buildings.
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Development of environmentally friendly PVC compositions
Scientific article
Introduction. Polyvinyl chloride (PVC) is one of the most important polymers in the economy. Due to its versatility, this material is now found in a wide variety of products used in everyday life. A wide range of physical and mechanical properties is given to it by the use of additives, the main of which are plasticizers. The most common in terms of consumption are orthophthalic acid esters, in particular, dibutyl phthalate (DBP), dioctyl phthalate (DOP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP). Phthalates are well combined with polymers, give them high physical and mechanical properties, therefore plastic compounds based on them are widely used in the construction sector, engineering, as well as in agriculture and in everyday life. Numerous studies of products made from plasticized PVC, conducted in different countries, have established the adverse effects of DOP on human health, which led to the limitation of its areas of application. Legislative bans and growing consumer pressure are forcing PVC compound manufacturers to look for an environmentally friendly replacement for DOP. Methods and materials. In this research work, the possibility of creating more environmentally friendly PVC compounds using a mixture of plasticizers: industrial dioctyl phthalate and diisononyl phthalate and dibutoxyethyl phthalate (DBOEP) developed by us was studied. The choice of the plasticizers is based on the fact that DINP and DBOEP, in contrast to dioctyl phthalate, belong to the 3rd hazard class. Results and discussion. In the course of the correlation-regression analysis, a close functional relationship was obtained between the additives used and the characteristics of PVC, which was confirmed by the calculated coefficient of determination. Using the method of nonlinear programming applied to the constructed third-order polynomial dependencies, it was found that in the basic PVC composition formulation it is promising to replace up to 25 wt.h. DOP on DINP plasticizer. The joint use of industrial plasticizers DOP and DINP, as well as the developed DBOEP in the formulation of PVC compositions, indicates an increase in plasticity and manufacturability. This can probably be explained by the synergistic effect of the studied plasticizers. The dependence of the properties and content of plasticizers DBOEP and DINP in the form of a second-order surface was studied on the basis of the obtained experimental data, the level lines of the constructed function of two variables were studied, as a result of which it was found that the greatest effect is achieved at a dosage of: DOP – 25 wt.h., DINP – 5 wt.h. and DBOEF – 20 wt.h. Conclusion. The obtained research results show that the proposed formulation of the PVC composition makes it possible to reduce the toxicity of the plasticizers used by 50 % and improve the physical, mechanical and technological characteristics of the compounds.
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Development of heavy metal-based nanostructured complex technology for use in building mortar
Scientific article
Introduction. Heavy metals (copper, zinc, nickel, lead, chromium, cobalt, cadmium) get into constructional materials with natural and man-made raw materials. The chemical and mineralogical composition of large-tonnage wastes from the petrochemical industry is perfect for constructional materials production. Heavy metals in constructional compositions provide high strength and frost resistance. Currently, nanostructured metal-containing complexes are used in the production of mortars. Therefore, it is necessary to ensure the reliable binding of heavy metals into structurally stable compounds to avoid their emission and secondary environmental pollution. The steadily growing volumes of sludge reservoirs with high concentrations of heavy metals such as chromium (Cr +6), copper (+2), lead (+2), iron (+2), and Fe (+3) cause particular interest to researchers. Qualified extraction of the listed metals and binding them as nanocomponents in the composition of the complexing agent will ensure the creation of a nanostructural composition in the recipe for the preparation of mortar for various purposes. Methods and materials. Sorption methods are the main way to isolate heavy metals. The paper proposes a method for the production of alkyleneaminopolycarboxylic acids and studies its ability to form nanometallic complex compounds for the extraction of heavy metals. Results and discussions. In order to bind metal nanoparticles in oil sludge, the efficiency of the produced compounds, carboxymethyl derivatives of hexamine, was investigated. Optimum synthesis conditions were selected and the structure of the obtained complexing agents was proved by infrared and ultraviolet radiation methods as well as by the method of nuclear magnetic resonance. Conclusion. The resulting nanostructured additions have binding properties that provide high adhesion of the heavy metal to the organic substrate and mortar components, which makes it possible to provide a strong composition that maintains operational properties that meet technical requirements.
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Development of new methods for energy technology processing of Kyrgyzstan coals
Scientific article
Introduction. This study explores methods for determining the yield of volatile matter from Kyrgyz coal and obtaining ultra-pure carbon for potential applications in modern carbon nanotechnologies used in the construction industry. Both organic and inorganic components of various coal types were analyzed, along with the composition of the released volatile substances. Methods and materials. We used in the research empirical methods (observation, experimentation, measurement, and comparison), alongside chemical methods involving acid treatment (for the removal of metallic impurities) and a transport reaction method (for the removal of silicon oxide impurities). The study focused on obtaining ultra-pure carbon from bituminous coal deposits in Kyrgyzstan. The tested raw materials included grey and brown coals from deposits in the southern region of Kyrgyzstan. Pre-weighed samples were placed in a stainless-steel reactor and subjected to slow pyrolysis under sealed conditions across specific temperature ranges. For brown coal, pyrolysis was conducted between 100 °C and 550 °C, while for bituminous coal the range was 100 °C to 1100 °C. The process continued until all liquid and gaseous pyrolysis products ceased to be released. Results. Pyrolysis was used to remove volatile liquid and gaseous impurities from the coal samples. The qualitative and quantitative composition of the volatile gases was determined. During pyrolysis in the 100 °C to 850 °C range, pyrogenetic water was formed, and gaseous products such as NO, CO₂, CO, H₂S, CH₄, and others were released. For brown coal, the yield of volatile substances at 150–170 °C was 61.9%. For bituminous coal, at 380–400 °C, the yield was 15.5%. Post-pyrolysis, the remaining coal contained only solid impurities – primarily metallic elements and silicon dioxide (SiO₂). These were removed using a chemical method involving a mixture of concentrated sulfuric and nitric acids in a 1:3 ratio. Silicon dioxide impurities were removed via a transport reaction facilitated by gas convection. As a result of this two-stage purification, ultra-pure carbon consisting solely of carbon atoms (C–C–C–) was obtained. Conclusion. The proposed experimental setup and technological scheme for impurity removal and carbon purification – including the use of transport reactions – enable industrial-scale production of ultra-pure carbon from coal. This purified carbon can be used as a component in advanced construction nanomaterials. The use of such materials significantly enhances the performance characteristics of construction structures and coatings, while also reducing the environmental impact of combustion by-products, ultimately lowering costs associated with environmental protection.
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Scientific article
Introduction. The geotechnical environment is a dynamic system, the parameters of which are pivotal in determining the reliability and safety of building and structural engineering works. Deterioration in soil properties, whether of a natural or human-induced origin, gives rise to conditions that deviate from the design specifications, thus necessitating the implementation of protective measures in the form of soil stabilization. The process entails the reinforcement of soil, resulting in the formation of a three-dimensional geotechnical massif. In this context, the microstructure of the treated soil is partially or completely filled with an grouting mixture. This enhancement leads to improvements in both cohesion and de-formation characteristics, relative to the initial values. Injection methods have been employed extensively to address a wide range of geotechnical challenges, with the objective of stabilizing and enhancing soil properties using polymeric or mineral compositions. However, the requirements for such compositions are often either not specified or stated only in general terms, and many methodologies and the underlying assumptions for design justifications are lacking. The formulation of such requirements constitutes a pivotal element in the advancement of injection technologies and the establishment of a design and technical framework. Materials and methods. A rigorous analysis was conducted to ascertain the primary deformation parameters of stabilized soil treated with grouting mixtures. This restructuring of the soil mass enhances its properties. The performance of fast-setting polymer systems was also analyzed. The subjects’ rapid development of strength is indicative of their suitability for emergency operations. Results and Conclusion. An analysis of the results indicates that grouting mixtures can enhance the properties of soil masses, suggesting the efficacy of such technologies, even in complex engineeringgeological settings. These findings imply that injection methods are practically applicable to a wide range of weak soils.
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Scientific article
Introduction. At present, the use of polymer coatings in the protection of metallic materials and structures is becoming popular in the construction industry. It is especially important to obtain nanostructured polymer insulating materials with high anticorrosive properties in order to ensure the service life of the equipment of the fuel and energy complex. Technological equipment during the extraction, transportation, processing of petrochemical raw materials is subject to regular exposure to aggressive environments. Damage to production equipment causes annual environmental damage and human health and material burden on the enterprise. The introduction of heteroatoms into the structure of the polymer molecule helps to improve the physico-chemical characteristics of polymer coatings, in particular, to increase the protective properties, since natural and synthetic polymer compounds represent a large cluster of supramolecular structures located in a certain sequence. Methods and materials. A technology has been developed for obtaining new polymeric nanostructured alkenylsuccinimides with anticorrosive properties, which can be used as part of lubricating coatings in various industries, including construction. Alkenylsuccinimides were tested according to TS 38101147-77 for succinimide additives and showed compliance with their standards TS 38101247-77. Results and discussions. In the course of the research a resource-saving non-waste technology of obtaining a nanostructured polymer additive with polyamines as a nanostructuring base to provide an anticorrosive effect has been developed. Conclusion. The obtained compounds based on triethylenetetramine, tetraethylenepentamine, alkenylsuccinic anhydride can be used as effective polymeric anticorrosion additives in the processing of metal materials and structures in the construction industry.
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Development of the actual state principle for a physical system
Scientific article
Introduction. The article briefly discusses the state of scientific research in the field of mathematical modeling of physical systems with distributed parameters. Mathematical modeling in elasticity theory. The initial boundary value problem of linear elasticity theory is formulated. It is shown that using measured and unmeasured variables, it is possible to construct a positive definite energy relationship, which allows not only to use the variational technique to find an approximate solution, but also to design objective estimates of its quality. Two-dimensional problem of elasticity theory (static case). Using the example of solving a two-dimensional static problem of linear elasticity, the advantages of the proposed approach are discussed in detail. Mathematical modeling in fluid theory. The variational principle in fluid theory is formulated. Optimal pressure control. Using the example of solving the problem of the motion control for ideal and viscous fluids in pipeline systems, the issues of finding an approximate solution and estimating its accuracy are discussed. Energy principle in the heat transfer problem. The variational principle in the linear heat transfer problem is formulated. Two-dimensional heat transfer problem. The features of constructing a solution to a control problem in a two-dimensional heat transfer theory are discussed in detail. Generalizing principle. A generalizing principle of the actual state of a physical system is formulated, which can be effectively applied for a detailed description and analysis of physical processes.
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Scientific article
Introduction. This research focuses on the study of the composition and properties of fine-grained self-compacting concrete, including the development of a methodology for designing their structure. Methods and Materials. The following materials were used: Portland cement CEM I 42.5B; crushed stone screening of 2.5–5 mm fraction from the Kurlek quarry in the Tomsk region; sand from the Tuganskoye deposit was used as fine aggregate; quartz flour was used as microfiller; a complex modifying additive consisting of microcalcite from the Dalnegorsk mining quarry and nanosilicon dioxide obtained by the arc plasma evaporation method. Results and Discussion. The proposed methodology incorporates a computational and experimental approach that enables the selection of optimal combinations of aggregate fractions, fillers, and developed additives to achieve the required grain packing density. The use of statistical methods, such as polynomial approximation and Gaussian process regression, allowed us to identify the relationship between particle size distribution and concrete properties. Optimal ratios of each quartz aggregate fraction from man-made raw materials were determined for specific self-compacting concrete requirements in terms of concrete mix flow and hardened concrete strength. Conclusion. Laboratory tests confirmed the accuracy and effectiveness of the proposed calculations. Self-compacting concrete grade B40 compositions with reduced cement consumption (412 kg/m3) and high-performance` characteristics were developed.
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Digital twin of a building as the basis for the application of nanotechnologies in construction
Scientific article
Introduction. The purpose of the conducted research is to analyze the possibilities provided by the “digital city” system and the prospects for the application of nanotechnologies. The objective of the research is to determine the possibility of digitalization in city management and the process of making more substantiated decisions regarding real estate operation. The practical application opportunities of the research results are due to the feasibility of implementing the author's approach to analyzing the operation of urban systems in general and “smart home” in particular. Methods and materials. The article explores the concept of “digital twin of a building,” its functions, components, features of construction and operation using digital twin technologies. The concept of digitalization is characterized, as well as mechanisms for introducing innovations into urban life. It is demonstrated that the “digital city” incorporates various innovative technologies: Internet of Things, artificial intelligence, data analytics, cloud computing, etc. The technologies utilized by the “digital city" not only collect data on urban life but also employ obtained data for managing electricity supply, waste collection, ensuring people's safety, and as elucidated in the article, transportation systems. Discussion. Digitization in urban management helps to create a more convenient and sustainable urban environment, a goal pursued by the governments of many countries. The implementation of sensors, detectors, and the analysis of data obtained from them provides an opportunity to improve the quality of life for urban residents and increase the efficiency of resource utilization. As a pleasant “bonus,” all of this allows making the living environment of citizens more environmentally friendly, addressing an issue that has been a “headache” for many governments – the issue of greening human existence in the city. After all, reducing the number of traffic jams automatically reduces the amount of carbon dioxide emissions, and turning on city lighting based on sensor signals saves electricity due to a reduction of consumed kilowatts since the bulbs are not unnecessarily lit. To address these issues, the use of nanotechnologies is proposed, which will enable ordinary building materials to acquire new unique properties. The emergence of nanotechnologies and their application can solve the problem of energy conservation in the construction industry. Moreover, nanotechnologies not only allow for the production of new products with unique properties but also enhance the efficiency of materials used in construction. In this regard, the key question for determining the application of nanotechnologies is the exploration of their integration into the digitization system of city management, which already incorporates a multitude of innovations and new technologies that help optimize the work of municipal services and improve the quality of life for urban residents. Conclusions. The author concludes that the provision of services by many urban services is based on 3D design technologies, as well as data collected within the framework of the “digital city” system.
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Scientific article
Introduction. The porous composite and nanocomposite materials discussed in this publication are metallized carbon-graphite materials, in particular carbon fiber materials (CFMs). At metallization of CFMs one of the actual problems is the task of applying uniform metal coating on the surface of CFMs fibers over the entire volume of the processed material. One of the most effective ways to coat CFMs with metals and their alloys is the galvanic method. This method allows, among other things, to optimize the process by optimizing both the design of the electrolyzer with flow-through three-dimensional electrodes (FTE) and the choice of electrodeposition modes, such as galvanic, concentration, and hydrodynamic. Materials and methods. Methods of mathematical modeling of porous medium metallization processes and previously published experimental data were used to solve problems on calculation of operating modes and elements of the electrolyzer design, in particular, the specific reaction surface of the UWM distributed over the thickness of the electrolyzer. Results and discussion. The development of mathematical models of the processes of electroplating metallization of CFMs is carried out. Boundary value problems of mathematical physics are formulated and calculation methods are proposed. Problems of optimization of distribution of specific reaction surface of CFMs by thickness of FTE on the basis of electrochemical theory of processes in porous medium are set, ways of their solution are presented. Specific technological problems are solved. The comparison of the most effective values of the distribution of specific reaction surface of CFMs over the thickness of FTE obtained as a result of modeling with the experimental data is given. The workability of models and methods for studying the process of copper electrodeposition from sulfuric acid electrolyte is shown. Conclusion. Calculation of regularities of electrochemical processes of metal extraction in FTE on the basis of the developed mathematical models allows to predict the results of electrolysis, determine the optimal modes of operation and elements of FTE design. The use of FTE for metallization of CFMs with properly distributed reaction surface contributes to obtaining composite materials with specified properties.
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Scientific article
Introduction. Currently, carbonate reservoirs play an increasingly significant role in the global hydrocarbon balance. Most of the deposits discovered in recent years are fractured carbonate reservoirs. The potential for effective development of carbonate reservoirs lies in the development and application of new high-tech methods and advanced well drilling technologies. The article highlights the challenges of developing productive deposits in the Paleozoic basement of Tomsk region deposits represented by fractured carbonate reservoirs. The article considers the mining and geological conditions of carbonate reservoirs in the Paleozoic basement and the challenges that arise when using traditional drilling technologies. The article presents the results of an analytical review on the application of advanced technologies for drilling wells with horizontal completion. Some aspects of the application of nano drilling fluids for conditions of low-permeability carbonate reservoirs are highlighted. The content of the article is based on the author's research and analysis of publicly available literature. Methods and materials. The work is based on the generalization, systematization and analysis of factual material, scientific publications, and results of analytical studies. Results. Based on the generalization and analysis of geological and field data, the authors established that in the conditions of the identified group of fields, when developing fractured carbonate reservoirs, the productivity of a well depends on the number of natural cracks opened during drilling that penetrate carbonate rocks. Fault tectonics had a major impact on the development of highly fractured zones of carbonate reservoirs, which are the main reason for frequent absorption of drilling fluid when drilling wells with a horizontal end. Clustering of the well stock of the development object in carbonate reservoirs allowed to identify 3 groups of wells, opening up deposits with different filtration-capacity characteristics. It was established that the nature of the distribution of porosity and permeability depends on the development of reservoir fracturing associated with the position of tectonic faults. Analytical studies in the perimeter of Russian oil and gas companies have shown that the efficiency of well drilling technologies in fractured carbonate reservoirs is achieved through an integrated approach: detailing the geological structure of the target object, adapted drilling technology with the ability to regulate differential pressure in the well-formation system, as well as selecting optimal drilling fluids.
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Dry building mixes with a silica-based modifying additive
Scientific article
Introduction. The use of dry building mixes has broad potential for use in construction due to their stability of properties, the ability to provide a specific set of quality characteristics to the material, and reduced production waste. When developing compositions of floor dry building mixes, it is necessary to ensure high mechanical properties, reduce shrinkage deformations, crack formation, and provide high adhesion to the concrete base. Expanding the range of dry building mixes, using local raw materials and modifying additives for various functional purposes for their production is an urgent task for the construction industry. Materials and methods. To ensure the rheological and technological properties of the dry building mixes, low water demand binders were produced based on Portland cement, volcanic slag, fly ash and dry superplasticizer on a polycarboxylate basis. To regulate the technological properties and increase mechanical properties of dry building mixes, a reinforcing additive in the form of basalt fiber and nanosilica was used. Results and discussion. The compositions of self-leveling dry building mixes were optimized according to the criteria for achieving the highest mechanical properties. The water-holding capacity of the mixes, compressive and flexural strength, water absorption, crack width, abrasion, and adhesion strength to the concrete base were determined. The microstructure of the mortar was studied using scanning electron microscopy. An assessment was made of the influence of modifying additives on changes in the properties of flooring dry building mixes. Conclusion. The resulting compositions of dry building mixes comply with the requirements of state standard for self-leveling flooring building mixes. With the use of a complex of mineral, plasticizing, micro-reinforcing, nano-sized additives, high performance indicators of flooring building mixes have been achieved.
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Scientific article
Introduction. The use of SiO2 and Al2O3 nanoparticles opens new possibilities for controlling the structure of cementitious materials. However, their influence on the aggregative stability of the coagulation structure and on the strength, characteristics has been insufficiently studied. This study established the effect of SiO2 and Al2O3 nanoparticles on the relationship between aggregative stability, early-age structure formation kinetics, and the strength of cementitious materials. Materials and Methods. Three cementitious systems based on Portland cement CEM I 42.5 were investigated: a reference system with a superplasticizer (Sika®ViscoCrete® 20 HE), as well as systems with the addition of SiO2 nanoparticles (dav = 10 nm, 0.01% by cement mass) and Al2O3 nanoparticles (dav = 50 nm, 0.1% by cement mass). The kinetics of early structure formation were evaluated by plastic strength using a cone plastometer. Aggregative stability was determined by compression rheometry using an Instron 5982 testing machine. The phase composition was established by X-ray diffractometry. The microstructure of the specimens was studied by scanning electron microscopy. Compressive strength was recorded after 1 and 28 days. Results. It was found that Al₂O₃ nanoparticles most significantly accelerate the process of early coagulation-crystallization structure formation in cementitious materials (the exponent of the kinetic equation is 1.13 without a change in the controlling process), increase aggregative stability by a factor of 2–3, but reduce plastic deformation. SiO2 nanoparticles maximally accelerate the hydration process (degree of hydration 93% after 28 days of hardening) while forming low-basic hydrosilicates. The 28-day compressive strength of cementitious materials modified with SiO2 and Al2O3 nanoparticles was 92.7 MPa and 96.4 MPa, respectively, which is significantly higher than that of the reference system (51.1 MPa). Discussion. The twofold increase in strength is attributed to different mechanisms: for SiO2 nanoparticles – their high pozzolanic activity and accumulation of high-strength cementitious phases; for Al2O3 nanoparticles – an increase in the aggregative stability of the coagulation structure, which ensures the formation of a homogeneous crystallization structure without major defects. Conclusion. Complex modifiers based on SiO2 and Al2O3 nanoparticles enable targeted control of both the hydration activity and structural homogeneity of cementitious materials, providing a strength increase of up to 1.9 times.
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Scientific article
Introduction. The effect of adhesion additive and nature of filler on fatigue life and interfacial interaction in mastic is analyzed in this paper. Materials and methods of research. Frequency sweep from 0.1 to 100 rad/s at strain 0.05% at temperatures from 30 to –10°С with a step 10°С and cyclic tests (LAS test) at temperatures from 16 to 1°С with a step 3°С for bitumen grade BND 100/130 and mastics based on it, containing fillers of different nature, were performed on the dynamic shear rheometer. Mastics were prepared by mixing bitumen (3 min; 160°С and 600 rpm) and filler (filler volume fraction – 0.275). Adhesion additive in an amount of 0.7%, was introduced into bitumen before the filler to investigate the effect of AD on the properties of bitumen and AB. The damage characteristic curve under cyclic loads was calculated using two models of VECD theory (Viscoelastic Continuum Damage Modeling System): dissipated strain energy and pseudo-strain energy. Results and Discussion. The influence of nature and properties of filler, adhesive additive, temperature and frequency of tests on the parameter of interfacial interaction K-B-G* and thickness of adsorbed layer has been investigated. The intensity of damage in the specimen under cyclic loads and the behavior of fatigue parameters as a function of test temperature at two variants of determining the parameter α have been analyzed. Conclusion. It is shown that an increase in the interfacial layer thickness in asphalt mastic leads to an increase in their resistance to damage accumulation (Damage Intensity) during fatigue testing (LAS), and lowers the rate of pseudo-deformation energy growth.
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Effect of laser modification on composite films with nanodispersed SiO2
Scientific article
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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Scientific article
Introduction. The article addresses the problem of improving the lubricating capacity of drilling fluids to reduce the coefficient of friction in a ”metal-to-metal“ pair, which is crucial for preventing stuck pipe incidents and reducing equipment wear during directional and horizontal drilling. Methods and materials. An analysis of modern approaches to the use of lubricating additives in drilling fluids is presented. The effect of various types of additives – paraffins, ”EZО“ nano-additive, fatty acids, waste oil, as well as compositions with surfactants – on the coefficient of friction and friction reduction efficiency in a polymer-clay fluid was experimentally studied. Tests were conducted on an OFITE E.P. lubricity tester at additive concentrations ranging from 0.2–2.0% by volume. It was shown that the greatest effect is achieved with the combined use of surfactants and nano-hydrocarbon components, providing a reduction in the coefficient of friction of up to 71% at an oil content of 2%. Results and discussion. Optimal component concentrations were established and synergy effects were identified upon the combined introduction of additives. The obtained results allow recommending the developed nano-compositions for use under high-load conditions in a ”metal–metal“ friction pair during high-angle drilling. Conclusion. Based on the conducted research, it was established that the highest efficiency (reduction of the friction coefficient up to 71%) is achieved with the combined use of surfactants and waste oil at a concentration of 2%. A synergistic effect was revealed upon the combined introduction of additives, and it was also established that exceeding the oil concentration above 0.5% reduces the efficiency of most additives, with the exception of compositions with surfactants. The developed formulations are recommended for use as a cost-effective and efficient alternative for lubricating ”metal-to-metal“ sliding contact during horizontal drilling.
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Effect of nanofibrillar cellulose on the cement paste setting kinetics
Scientific article
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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Scientific article
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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