Nanotechnologies in Construction: A Scientific Internet-Journal @nanobuild-en
Статьи журнала - Nanotechnologies in Construction: A Scientific Internet-Journal
Все статьи: 538
The photocatalytic activity of cement-sand plaster under the influence of natural solar radiation
Статья научная
Introduction. Concrete and cement composites can be considered as the most demanded and versatile building materials nowadays. Recently, photocatalytic building materials containing nano- and finely dispersed oxides and salts photocatalyst particles, especially titanium dioxide of anatase modification, are becoming widespread. Under the influence of light, the surface of these materials becomes capable of self-cleaning. The materials photocatalytic activity is usually determined in the laboratory conditions by irradiating samples with an artificial source of light with certain wavelength, which does not fully characterize the behavior of the material in real-life conditions. Therefore, the purpose of this study is to evaluate the photocatalytic activity of cement-sand plaster samples under natural solar radiation. Materials and methods of research. In this study, the properties of cement-sand plaster modified with an additive of industrial TiO2 were studied. The additive was introduced into the plaster compositions in amounts of 0.3; 1.0; 1.7; 3.0; 5.0 and 10.0 wt.% during the dry mixing of the components. At the first stage, the effect of the additive on physical and mechanical properties of the samples was investigated. The second part of the research is devoted to the study of the photocatalytic properties of the material. Mineralization of the model pollutant Methylene blue was carried out in real-life conditions under sunlight irradiation, the photocatalytic activity of the samples was evaluated in accordance with the European standard UNI 11259-2016. Results and discussion. As a result of the study, the authors found that the maximal increase in compressive and flexural strength corresponds to the sample with 5.0 wt.% of TiO2, and the maximum degree of Methylene blue decomposition corresponds to the sample with 10.0 wt.% of TiO2. Thus, compressive strength increases by 69% at 2 days age, by 58% at 7 days age, and by 50% at 28 days age compared to the control sample. Flexural strength increases by 10, 13, and 50% at 2, 7, and 28 days age, respectively. The strength of the samples with 10.0 wt.% of TiO2 remains approximately at the level of the control sample. Compositions with TiO2 starting from 3 wt.% demonstrate photocatalytic activity (R), the highest R corresponds to 10 wt.% sample with R value is 40–78%. It is also noticeable that the maximum Methylene blue mineralization (58–78%) is observed after 2 days of sunlight irradiation, after 7 days there is a significant decrease in the degree of pigment decomposition. Conclusion. As a result of the research, the authors concluded that the optimal amount of TiO2 photocatalyst in the cement-sand plaster is 5.0–10.0 wt.% since these samples exhibit maximum strength characteristics combined with a high ability of model contaminant degradation.
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The physical and mechanical properties of concrete with multifunctional additive
Статья научная
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.
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The potential of nanotechnology: issues of heat supply and heating of buildings
Статья научная
The article explores the possibility of using nanotechnology to improve the efficiency of centralized and autonomous heating systems on the way to a new technological model. A logical sequence of the development of heat supply and heating is given, conservative equipment and technologies that are used to supply thermal energy to consumers is marked. In the context of the urgent tasks of heat supply and heating of buildings, the concepts of the use of nanotechnologies that meet the goals of maximum heat transfer intensification are considered. Heat conduction analysis, concentration, size, mass and velocity of nanoparticles assesses are the basis for assessing the possibility to use nanofluids as a coolant for improving heat exchangers and to reduce heat losses in heating systems to maximize efficiency of their work. It is shown that the use of nanostructures affects the saving of coolant flow as the main task of the qualitative and quantitative regulation of the heat supply system. Attention is focused on the application of nano-structured materials in low-temperature fuel cells used decentralized heating systems for heating houses.
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Статья научная
Introduction. In the context of the global fight against climate change, the reduction of CO2 emissions and its utilization is a topical theme. One of the promising directions is the utilization of CO2 in construction, in particular, in concrete production. The present research investigates the effect of carbon dioxide on the formation of nanoscale structure and physical and mechanical properties of concrete mixtures. Methods and Materials. A special unit for mixing cement, sand, water and CO2 under pressure was developed for the research. The obtained concrete specimen were subjected to compressive and flexural strength tests using MATEST E161-03N automatic dual range testing press. The microstructure of the specimen was also analyzed using scanning electron microscope (SEM). Discussion. The experimental results showed that the introduction of CO2 into the concrete mixture promotes the formation of nanoscale structure, which improves its strength properties up to a certain pressure. With further increase in pressure, deterioration of these characteristics is being observed. Additional mixing time and increase in water volume also affect the strength of concrete and its microstructure. Conclusion. The use of CO2 in concrete production can significantly reduce the carbon footprint of construction materials and improve their physical and mechanical properties due to the formation of nanoscale structure. Further research and optimization of mixing parameters are necessary to create stronger and more stable concrete mixtures.
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Статья научная
Introduction. The use of modifying nano-additives in the production of binding building materials is one of the most effective ways to control the technological parameters of concrete by conducting good control of the rheological characteristics reliability. Plasticizing additives increase the water-holding capacity of building compositions, which leads to the dispersed nanosystems stability. This article is focused on examining the physical and chemical mechanisms of the supramolecular effects of polycarboxylate ethers on technological and rheological characteristics of cement nanobinders. Methods and materials. This study describes controlled hardening processes of concrete nanocompositions with demanded technological characteristics in the presence of highly effective plasticizers. Moreover, this paper carries out the analysis of the innovative trends in regulating the consistency of building nanocomposites with the use of new comb-like polycarboxylate esters, which as superplasticizers allow to purposefully influence the kinetics of structure formation of cement nanocomposites. Results. Electrostatic and steric repulsion mechanisms, as well as the dispersing effects of innovative and traditional plasticizing nanoparticles, affect the adsorption and diffusion layers of the hydrated cement nanobinders ultrastructure. The most effective plasticizing properties are shown by comb-like polycarboxylate esters (CPE) with a linear chain molecular weight of ≈12000 g/mol and a length of side branches which correspond to a molecular weight of ≈750 g/mol. The supramolecular mechanism of nanosteric van der Waals repulsive forces begins to be detected at a distance of ≈11 nm, and the elasticity of the lateral branches of innovative CPE is ≈ 5 nm. Individual segments of CPE macromolecules enter the diffuse layer of dispersed nanosystems due to lateral interactions of anions of functional groups, hydrophobic fragments, etc.; they enhance the plasticizing effect of cement binders in concrete nanocompositions. Discussion. When using superplasticizing CPE, the density of concrete nanocomposites can be increased by reducing the amount of water mass to the cement mass ratio to the optimal 0.3; at the same time, technological pumpability and reliability control of the joint hardening kinetics with fillers are preserved within the framework of the technological problems system solutionsconcept. Supramolecular interaction of «anchoring» functional groups of polyacrylic acid containing solid phase cations of cement microparticles, fractal clusters of calcium hydrosilicates and simultaneous steric stabilization of polyethylene glycol radicals give the necessary rheological characteristics to construction nanocompositions and allow the construction of high-strength 55÷80 MPa building materials. Conclusions. The branched comb-like nanostructure of polycarboxylate esters exhibits effective technological characteristics of superplasticizers for concrete, building mortars and dry building mixes.
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The use of geosynthetic materials to increase the bearing capacity of soil cushions
Статья научная
Introduction. The development of Kazakhstan's megacities has led the construction sites to the territories with weak, macroporous soils. Construction on such soils requires a set of measures to strengthen and improve their mechanical properties. Methods and Materials. The article discusses the development of a method of surface hardening by replacing weak soil. This development is associated with the use of different types geosynthetics. The principles of operation of a soil foundation reinforced with various geosynthetic materials are considered. The mechanical properties of geotextiles, geogrids and geogrids used to harden embankment soils have been studied. A new test procedure for geosynthetic materials has been developed. This procedure differs from the traditional method specified in GOST 32491 with a constant deformation rate. Results and Discussion. Tests of geosynthetic materials in kinematic mode have shown that a decrease in tensile strength is observed for all materials. The reduction ranges from 28% to 42% for different types of geogrids. The elongation at break decreased for the hexagonal and biaxial geogrid by 8.6% and 30%, respectively. An increase in relative elongation was noted for a uniaxial geogrid. According to geotextile, the tensile strength decreased by 15.7%, and the elongation increased by 26.5%. Conclusion. Research results have shown the effectiveness of the recommended reinforcement methods to increase the bearing capacity of the bases and the possibility of their application in various regions of Kazakhstan.
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The use of nanomaterials in pipe insulation
Статья научная
The nanotechnologies applied in engineering will increase its energy efficiency. The use of nanomaterials will make it possible to reduce costs. Currently, the search for nanomodified materials is relevant for the construction industry. Various carboncontaining structures are used as nanodispersed modifiers. Taunit has been selected as carbon nanomaterial. This nanomaterial is packaged multilayer nanotubes with a conical shape of graphene layers. To conduct this research samples of foam concrete cements have been studied. To improve the mechanical properties of the cement stone, elongated nanoparticles with high strength were used. They reinforce cement mortar, at the same time being the centers of crystallization and increase the strength of the nanomaterial. In the course of experiments, carbon nanotubes «Taunit» were added to the foam concrete in the amount of 0.005–0,0005% by weight of cement. In the manufacture of nanomodified foam concrete it is important to ensure uniform distribution of nanoparticles. The studied cement stone chips were sprayed with Au / Pd alloy in a Quorum 150T ES vacuum unit in a 80/20 ratio. The microstructure of solid samples of cement material was investigated by means of a high-resolution auto-emission electron microscope Merlin of CARL ZEISS. When multi-layered carbon nanotubes of “Taunit” brand were introduced into the cement mortar, the relief microstructure of the cement was characterized by a heterogeneous and loose structure. In the course of testing the strength of the investigated samples, the following results were obtained: under bending loads applied to cement-sand mortar for 7 days, hardening increased by 35%, and after 28 days – by 30%; under compressive loads, the increase in strength is 42% and 22%, respectively, relative to the original composition without the addition of nanomodified materials. The addition of nanodispersed modifiers to the cement stone made it possible to increase the strength of concrete and foam concrete. Based on the obtained nanomodified foam concrete, a device for insulating pipelines has been proposed.
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Three-Arch, Three-Cable Face Steel-Sided Rigid Tie Composite Arch Bridge
Статья научная
This essay proposes a new structural system for a large span three-arch, three-cable face steel edge main beamrigid tie composite arch bridge. The authors invented a new structural form of a steel edge main girder rigid tie, and developed and designed a key arch-bar three-dimensional six-way space node structure. The analysis of results show that: compared with the traditional arch bridge, the large span three-arch three-cable face steel-sided main beam rigid ties composite arch bridgeis beautiful in shape, hasareasonable structure and efficient construction. It is a high-strength, high-performance composite structural system, with better strength, stiffness, stability and dynamic performance, which overcomes the large span ultra-wide bridge deck arch bridge horizontal thrust, poor transverse stability, and the key technical problems of acable joint control. The proposed structural form has a wide range of engineering application prospects.
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Статья научная
Introduction. Increasing demands for sustainability and environmental safety in construction materials have encouraged the use of industrial by-products such as Basic Oxygen Furnace Slag (BOFS) and fly ash (FA) as alternative components in geopolymer binders. This study aims to evaluate the physico-mechanical properties, micro- and nanostructure, and resistance to alkali-silica reaction (ASR) of geopolymer mixtures based on BOFS and FA, which are particularly relevant for hydraulic engineering applications. Methods and Materials. BOFS and Class F FA were used as aggregates and pozzolanic components. Compressive strength was measured at 3, 7, 28, and 56 days. Micro- and nanostructural analyses were performed using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and X-ray Diffraction (XRD). Expansion tests were conducted according to ASTM C 1260 in both water and 1 M NaOH solution at 80 °C. Results and Discussion. The optimal compressive strength (up to 50 MPa at 28 days) was achieved with 75% replacement of sand by BOFS and an alkali activator ratio of Na2SiO3/NaOH = 1. SEM and EDS analyses revealed the formation of a dense gel-like structure with N-A-S-H and CaCO3 phases. All samples exhibited expansion below 0.1% in water, meeting the criterion for non-reactive aggregates. In alkaline solution, expansion reached 0.25% in some compositions. A correlation was observed between microstructure, the content of reactive phases (Si, Al, Ca), and mechanical performance. Conclusion. The results demonstrate that BOFS and FA can be effectively utilized in geopolymer mixtures, providing adequate strength, dimensional stability, and ASR resistance. Carbonation curing and proper selection of alkali activators enhance BOFS stabilization and reduce its expansive behavior. These findings support the potential use of such mixtures in sustainable and durable construction systems, especially for hydraulic structures.
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Use of nano-sized components in multilayer composite materials
Статья научная
Introduction. In our country, the use of composite materials for creating parts and structural components in the construction industry is not as widespread as it could be. Composite materials are multilayer structures made of reinforcing fibers, impregnated with a polymer binder, which is also an adhesive. The strength properties of layered structural materials are achieved through various reinforcing fillers and adhesive binders. Both glass fibre and carbon fibre fabrics and fibers themselves are widely available as layered materials. Various thermosetting resins (epoxy, phenolic, polyester, polyimide, polyamideimide, polyamide, etc.) are used as binding components. Among them, epoxy resins with high strength, wettability and adhesion to various materials are widely used. Layered composite materials (LCM) are used to make polymer reinforcement for reinforcing concrete structures, various pipes, shell frames to strengthen existing metal and reinforced concrete structures, load-bearing elements in light-loaded structures of bridges and crossings. However, at the same time they have a significant drawback – low interlayer strength (propensity to layering). As a result, the connection between the layers is disrupted, which leads to a significant decrease in the rigidity and strength of the structure. This phenomenon applies to all types of fabrics and fibers. Most often, defects in the form of layering are formed under the influence of shock loads. To improve the performance characteristics of such materials, various fillers have now begun to be used – powders (micro- and nano-sized) introduced into binder compositions. Main part. The analysis of the academic literature has shown that it is possible to increase the interlayer strength in structural elements made of LCM through the use of nanofilled binders and the introduction of nanoadditives into the interlayer space of layered materials. The article reviews the related inventions in Russia, USA, etc., which can be applied in the construction industry using nanodispersed components. With the widespread use of the presented materials (in bridges, pedestrian bridges and bridge decks, etc.), significant performance advantages can be achieved compared to materials traditionally used in the construction industry. Methods and materials. By comparing the data from the submitted patents for inventions, it was revealed that the introduction of from 2% to 5% of various nanocomponents to form a nanocomposite material provides a new means of modifying the physical properties of polymer binders. Results. It was revealed that the use of nanoparticles ensures the decrease in the fluidity of prepregs and the gelation time, and the increase in residual compressive strength and specific fracture energy – indicators characterizing the crack resistance of composite materials. As a result, fracture toughness, endurance and survivability increase. Conclusion. Increasing the reliability of composite materials leads to longer service life of products and structural elements in the construction industry.
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Use of pulp and paper industry waste in binding and cementitious materials technology
Статья научная
Introduction. Utilization of chemical cellulose fillers in construction industry is one of the ways of processing unused wastes from pulp and paper industry. Decorative, finishing, and heat insulation materials are widely used as construction materials. This paper proposes various compositions and insulation materials characterized by compressive strength of not less than 10 MPa, water tightness of 0.8, and density of not over 600 kg/m3. The likely curing mechanism is studied for cement systems. The possible mechanism of hardening structures formation in the systems is discussed. Methodology. Corrugated fibreboard МS-5B waste is used as a filler, high-early strength cement М-500 (CEM 47.5) – as inorganic binder, and elemental sulfur, polyethylene terephthalate, cementmodified polyurethane (PU) with the addition of nanosized silicon oxide are used as a polymeric matrix. Infrared spectroscopy, terahertz time-domain spectroscopy (THz-TDS), and scanning electron microscopy are used for investigations. Cement samples undergo compressive strength, water tightness and water absorption testing. Results and discussion. Physical and mechanical properties obtained for composites with the paper filler and polymeric matrix based on cement-modified PU, are described, and testing results are compared with the experimental data obtained for materials based on other binders. It is found that the paper filler–cement-modified PU composition is consistent with the purposes of this research. The understanding is improved for the curing mechanism of the polymeric matrix–paper filler system. The THz-TDS data demonstrate a correlation between the spectral transmission and thermal conductivity and density of synthesized heat insulation materials. Conclusion. Synthesized is the effective heat insulation material with relatively high compressive strength, low density, and high tightness to water. Scientific understanding of the curing mechanism is improved.
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Water purification from oil and petrol products by means of nano-porous super-hydrophilic materials
Статья научная
Introduction. This article reveals the research results of physical and chemical properties of the new filtering material, evaluation of its hydrophilic and oleophobic features as well as the efficiency of oil-in-water emulsions separation in laboratory conditions and in production. Methods and materials. As the base for creation of new filtering material a natural mixture of minerals with good prevalence of silicon earth also including some small amounts of fissile hydrous silicates (mica, clay) was chosen, which provide the durability of granulated end product at reservation of porosity and hydrophilic properties of the material surface. The research used spherical shape granules of various particle size obtained by drying, granulation and firing. Prior to filtration the granules are being impregnated with water aiming to obtain a water shell around each granule, which provides granules protection from oil and petrol products contamination as well as an easy filter cleaning by backwashing in fluidization mode. For the lab testing of oil-in-water emulsions separation parameters a test rig was built. In process a set of various tool methods of physical and chemical research was used. Results. The chemical and mineral composition of the developed filtering material and the results of its X-ray-structural analysis, photomicrography of ground substrate obtained with SEM are given as well as the porous structure data (pores size distribution and aggregate pores of granules material) obtained by the method of low-temperature nitrogen adsorption. The results of laboratory and pilot testing of separating and accumulating ability of the filtering material are presented. Interpretation. The obtained data prove the fact that the developed material possesses over the prominent hydrophilic properties, while after water shell creation also over the oleophobic properties. Upon exploration of the two liquid immiscible phases separation during the filtering through the granules obtained, a significant efficiency growth of the filter after attaining the special amount of oil and petrol products retained by the filter was detected. The efficiency increase of the filter is connected with formation of a prolonged structure, which was named by the authors a “fluid net”, created by the oil and petrol products entrapped. The strings of that “fluid net” being formed in the gaps between the granules are decreasing the sizes of the passages which lets the entrapping efficiency of finer oil and petrol products droplets grow. Conclusion. The obtained nano-porous granules of the filtering material exhibit super-hydrophilic properties and based on the water shell created around them provide the following: protection of granules from contamination with oil and petrol products contained in water to be purified; effective and not decreasing over the course of time filter regeneration by means of backwashing in fluidization mode; quality of water purification from oil and petrol products at the level of the most expensive purification methods. Prospective fields of applications. The “OreFilter” technology developed has passed the pilot scale validation on the basis of more than fifty industrial objects of different industrial branches (mainly on those connected with oil production and oil refining) in Russia and abroad. The technology is now being tested on industrial objects in the Near East, Canada, US, Brazil and Australia. The industrial filtering units using “OreFilter” technology are already in operation on Russian enterprises as well as in Sweden and Germany. The experimental-industrial tests have proved the application efficiency of the technology developed: in food industry; at the detergents and soaps manufacturing plants; at mining and processing plants; at purification of ballast and bilge water at ports; at purification of polluted water after oil tankers washing; in fish farming; in seaquariums and dolphinariums.
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Wood-polymer nano-modified composite materials for construction purposes
Статья научная
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.
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