Nanotechnologies in Construction: A Scientific Internet-Journal

90-99

Authors: Kozlova I.V., Dudareva M.O.

Introduction. Modification of traditional materials based on mineral binders with fine-dispersed and nano-additives is an essential way to create new functional construction materials with a set of unique characteristics. However, the main difficulty in this process is the method of introducing a finely dispersed component into the cement matrix and the uniformity of its distribution. The homogeneous distribution of the additive particles in the cement composite improves the physical and mechanical characteristics, intensifies the hydration of cement clinker minerals, and is leading to a more durable and dense cement stone structure. The main methods of introducing additives into the cement composition include joint grinding, dry mixing and the introduction of a stabilized suspension of the additive instead of mixing water. Thus, the purpose of this research is to compare the options for the introduction of additives based on the TiO2–Bi2O3 oxide system, which can provide the cement composite with improved physical, mechanical and structural characteristics and the ability to resist mold fouling. The object of this research is the cement compositions modified with an additive based on the TiO2–Bi2O3 system. Materials and methods. The studies were carried out to establish the optimal method of introducing a fine-dispersed additive based on the TiO2 –Bi2O3 system. At the first stage, the phase and granulometric composition of the additive was studied, then the additive was introduced into the cement composition in four different ways. The cement stone samples were obtained by dry mixing of the components then mixed with water, by mixing cement powder with water suspension of the additive after ultrasound processing, by mixing a dry mixture of cement and an additive with water-plasticizer solution, and cement powder mixed with water-polymer suspension of the additive after ultrasound processing. After that, the strength characteristics, porosity and ability of the samples to resist fungi fouling were investigated. Results. As a result of the study, the authors concluded that the highest physical and mechanical characteristics of cement stone can be provided by introducing an additive in the form of a stabilized water-polymer suspension. This method contributes to the formation of a more durable and dense structure of cement stone, with an increase in strength of 31; 38 and 44.8% at first day age, 28; 30 and 32% at third day age and 2.4; 9.0 and 14% at 28 days age relative to the control sample containing cement, water and plasticizer. It was found that the highest strength results were shown by a sample containing a stabilized suspension of an additive with a concentration of 50 g/l. The study of the cement stone porosity showed its decrease by 13% at first day age in relation to the control sample with a plasticizer, and by 10% after 28 days of hardening. It was also shown that samples modified with 50 g/l (1.7 wt.%) of the additive demonstrate resistance to bio-fouling. Conclusion. As a result of the research, the authors concluded that the optimal way to introduce a finely dispersed additive based on the TiO2–Bi2O3 system is to mix cement powder with a stabilized water-polymer suspension of the additive, resulting in a more durable and dense structure of cement stone, especially at an early stage of hydration, which can also resist fungi bio-fouling. Thus, the authors came to the conclusion that the cement compositions obtained by this method can be applied as repair compounds and tile grout in damp shaded rooms with favorable conditions for fungi colonization.

109-124

Authors: Vikhareva I.N., Antipin V.E., Enikeeva D.V., Kruchinina P.A.

Introduction. Coatings on hard materials are widely used in many industries. Coating technologies help prevent or reduce corrosion, contamination and biofouling, chemical and structural degradation, and wear and tear of external surfaces due to exposure to the elements and natural environments. The range of materials used for functional coatings is wide enough: from organic polymers to hybrid composites and inorganic nanoparticles, depending on the desired properties and functionality of the final product. Despite the excellent anti-corrosion characteristics of non-polymer coatings, their usage causes environmental damage. Organic coatings are among the most widely used. Such compositions are applied in liquid form; organic solvents are one of the major components. Environmental concerns have encouraged the development of alternative technologies. The main areas for development are availability of raw materials and the cost of environmentally friendly coatings. Results and discussion. The review substantiates the relevance of research on the development of multifunctional polymer-based coatings. The market for polymer coatings is presented. Methods of surface protection, types of coatings formed, their main components, features of the formation of coatings, the influence of various factors on the formation of polymer coatings, including methods of preparation and pre-treatment of the protected surface are presented. Methods for preventing corrosion are discussed in detail, as well as the primary lines in the development of anti-corrosion coatings based on various protective mechanisms. The characteristics of the main components of protective coatings are given. The issue of destruction of polymer coatings depending on the operating environment is considered in detail. The types of media, their influence and mechanisms of action on protected objects are considered. Factors and mechanisms of destruction of polymer coatings, methods for preventing degradation of coatings are listed. The latest technologies for the formation of protective polymer coatings are highlighted. Conclusion. Currently, coatings provide a wide range of quality indicators. An important characteristic of modern coatings is minimal negative impact on the environment, which requires an integrated approach to the design and production of coatings.

140-151

Authors: Massalimov I.A., Massalimov B.I., Akhmetshin B.S., Khusainov A.N., Mustafakulov Sh.S., Mustafin A.G.

Introduction. A method for protecting concrete and aerated concrete by treatment with a calcium polysulfide-based solution is considered. The solution penetrates into the pores of the materials and, after drying, forms a water-repellent nanoscale layer, protecting the material from water penetration. This ultra-thin layer is formed as a result of the destruction of calcium polysulfide molecules while drying the impregnating solution and gives the material hydrophobic properties. The paper presents research results of the properties and composition of the forming protective layer and its effect on water penetration into the materials. Materials and methods. In the article authors present data on water penetration into the studied concrete and aerated concrete samples, the size and composition of the hydrophobic agent using laser and X-ray diffraction, ultraviolet spectroscopy, as well as using visual research methods, including electron microscopy. Results. It has been revealed that the hydrophobic surface is formed from a mixture of sulfur and calcium carbonate. It is shown that concrete and aerated concrete impregnated with a calcium polysulfide-based solution acquires pronounced water-repellent properties, expressed in contact angles corresponding to superhydrophobic surfaces. The presence of sulfur was established by ultraviolet spectroscopy, and force microscopy showed the formation of nanocomposite particles from sulfur and calcium compounds. X-ray phase analysis showed that the protective layer deposited on the surface of the materials consists of sulfur nanoparticles (65%), as well as nanoparticles of calcium compounds – vaterite (21%) and calcite (13%). Surface treatment of concrete with a sprayer leads to a decrease in water absorption from 5.4% to 3.1%, and in the case of treatment by immersion to a value of 1.5%, while the use of preliminary vacuuming before immersion of the samples allows achieving a water absorption parameter of 0.9%. It is shown that impregnation with preliminary vacuuming leads to water absorption values of less than 1%, which indicates the practical water impermeability of samples of full-scale products (concrete curbs and pipes). Discussion. It is noted that during surface treatment of aerated concrete with a sprayer, a chemically resistant superhydrophobic layer in the form of a nanocomposite is being formed, which penetrates to a depth of 3–3.5 cm, reliably protecting the material from water and chemical penetration. Surface treatment is effective in cases where objects (facades, above-ground structural elements, etc.) are exposed to water in the form of rain. Treatment of concrete products by immersion and immersion treatment with vacuuming can be carried out in harsh cases of constant water exposure (underground utilities, tunnels, manholes). Conclusions. The limitation of water penetration, and in some cases the absence of water in the pores of building materials impregnated with calcium polysulfide, indicate the preservation of substance, since water is a carrier of substances that destroy concrete and aerated concrete. Accordingly, there is no destructive effect from freezing of water in the pores of such materials as a result of the formation of a nano-sized coating of sulfur particles. Comparison of the results for aerated concrete shows that it acquires superhydrophobic properties, which indicates its excellent modification and expands the possibilities of its use. The data observed for concrete products indicate that after treatment with a calcium polysulfide-based solution, they can be used under conditions of long-term and constant exposure to water.

170-179

Authors: Perevoshchikova A.N., Valtsifer I.V., Kondrashova N.B., Voronina N.S.

Introduction. It is known that concrete is the main building material, despite the introduction of new technologies. The combination of strength and durability makes this material indispensable for the construction of civil and industrial infrastructure. However, the impact of aggressive external factors on concrete structures, such as an acidic or alkaline environment, temperature fluctuations, and the presence of water at low temperatures, can lead to a significant decrease in their strength characteristics. The introduction of various additives based on organic and inorganic compounds into the composition of concrete allows for the regulation of its performance properties and protect concrete structures from the negative impact of the environment. Therefore, research works aimed at improving physical and mechanical properties and quality of concrete structures are relevant. Methods and materials. The objects of our research were concrete samples, prepared with and without the use of a multifunctional additive called “Betomix-ITH Gel”, which was developed by the researchers of the Institute of Theoretical and Applied Mechanics of the Ural Branch of the Russian Academy of Sciences (ITC UB RAS). The physical and chemical properties of the compared samples were studied in accordance with Russian and interstate regulatory documents in accredited laboratories of the Russian Federation and the Republic of Turkey. Results and discussion. As a result of the research, we have found that the introduction of the multifunctional additive "Betomix-ITH Gel" to the concrete mixture significantly increases the water resistance, frost resistance, and strength of concrete samples, compared to samples without the additive. It has been shown that Betomix-ITH Gel imparts the property of "self-healing" to concrete, with cracks up to 0.5 mm in size, and increases the resistance of steel reinforcement to corrosion. Conclusion. The research has proved experimentally the effectiveness of the Betomix-ITH Gel additive for improving the quality characteristics for concrete of various classes, which allows the use of this additive in concrete mixtures in the construction of reinforced concrete structures located in aggressive conditions.

189-197

Authors: Kotlyarevskaya A.V., Klimenko K.E.

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

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.