Nanotechnologies in Construction: A Scientific Internet-Journal @nanobuild-en
Статьи журнала - Nanotechnologies in Construction: A Scientific Internet-Journal
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The inventions in nanotechnologies as practical solutions. Part III
Статья научная
A brief review of patents is given. The research performed by scientists, engineers and specialists in the area of nanotechnologies and nanomaterials resulted in increased efficiency of construction, housing sector and adjacent fields of economy. For example, the invention «Construction structural element» refers to the field of construction. The building element is made of a cured mixture containing the following components, wt. %: dispersed foamglass – 60–85; 25–30% alumina solution in phosphoric acid – 13–34; basalt microfiber – 2–6; fulleroid type carbon toroid-like nanoparticles (fractions from 15 to 150 nm) – 0.009–0005. The dispersed foamglass is made in the form of foamed glass beads, on the surface of which a layer of polyparaxilylene 2–5 microns thick is applied. The mixture is cured at a temperature of 160–180оC. The technical result is increased strength, toughness, crack resistance and durability at low density, that is important when building objects, for example, to create internal walls and cellular partitions in rooms. The specialists can also be interested in the following inventions in the area of nanotechnologies: composite reinforcement, a method of manufacturing composite powder material from alumina carbon nanotubes; the method of plasma deposition of nanostructured heat-shielding coating; the method of degassing tungsten nanopowder; method to produce mixtures of highly dispersed heterophase powders based on boron carbide, etc.
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The inventions in nanotechnologies as practical solutions. Part IV
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A brief review of patents is given. The research performed by scientists, engineers and specialists in the area of nanotechnologies and nanomaterials resulted in increased efficiency of construction, housing sector and adjacent fields of economy. For example, the invention «Carbon ceramic fiber-reinforced composite material and method for its production» refers to a class of carbon-based composite materials of heat-shielding, structural, chemical-resistant purposes, can be used under static and dynamic loads when heated to 2000оC in an oxidizing environment (aerospace engineering, construction facilities for special purposes, high-temperature electrothermal equipment, equipment for nuclear reactors, etc.). The technical result of the invention is the strength of the composite increased up to 40% in terms of flexural strength and twice in terms of compressive strength. The specialists can also be interested in the following inventions in the area of nanotechnologies: building construction elements; a method for synthesizing a composite carbon material with metal nanoparticles with transferring a part of their electron density to a carbon matrix; a method of manufacturing marker of fuel and lubricants; wastewater treatment system with nano-modified natural sorbents; nanocrystal, hydrosol of nanocrystalline cellulose and method for producing it; a method for producing membranes for ultrafiltration of aqueous media; a method of obtaining transparent ceramics of yttrium-aluminum garnet; method and device for atomic emission spectral analysis of nanoobjects, etc.
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The inventions in nanotechnologies as practical solutions. Part V
Статья научная
A brief review of patents is given. The research performed by scientists, engineers and specialists in the area of nanotechnologies and nanomaterials resulted in increased efficiency of construction, housing sector and adjacent fields of economy. For example, the invention «A method to produce fireproof wood-polymer composites on the basis of secondary polyolefine» can be used in construction, car industry, shipbuilding, machine manufacturing, furniture trade and other industries. The method includes following stages: drying of composite components, mixing and heat forming of them by means of extrusion in extrusion Co- Kneader plant under treatment temperature120оС–150оС and conveyor screw rotation speed 350–450 RPM with further granulation. The obtained fire-resistant wood-polymer composite possesses high performance characteristics. The specialists can also be interested in the following inventions in the area of nanotechnologies: a method to produce strengthened nanocomposite with additional properties, anodic material for lithium-ion battery and a method to produce it, a method to rise breaking strength of composite material by preliminary impregnation of carbon fibers with carbon nanotubes, a method to produce carbon metal-containing nanostructures, a method to produce volume microscale structures from nanoparticles and a device to perform it, antistatic floor coating with carbon nanotubes and other.
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Статья научная
This study presents an investigation of the effects of high temperature on the thermal and microstructural properties of cement mortars modified with nanosilica. In the first stage of the research, the effects of nanosilica (NS) and silica fume (SF) on the hydration and compressive strength of cementitious composites were compared. In the second stage, four different types of cement mortars, containing an optimal dosage of NS, were produced. Two of them contained a normal weight aggregate (quartz or limestone), whilst two contained a heavy weight aggregate (barite or magnetite). Specimens without NS were produced for control purposes. The specimens were exposed to 300, 450, 600 and 800°C, with their post-heating properties – including thermal conductivity, specific heat, solvent absorption and cracking behavior – analyzed. The results show that NS exhibits significantly higher reactivity with cement than SF. NS accelerates the cement hydration process and contributes more significantly to the 28 and 365 day compressive strength of mortar, as compared to SF. The incorporation of NS in a composite substantially decreases the amount of CH in the mixture and leads to the production of additional C–S–H gel phase, which improves microstructure. The study also shows that NS contributes to a decrement in the thermal conductivity and density of mortar, both prior to and after heating. The incorporation of NS has a beneficial effect on decreasing the deterioration rate of mortars after heating, by decreasing absorption rate and the amount of cracks in in them.
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Статья научная
This study presents an investigation of the effects of high temperature on the thermal and microstructural properties of cement mortars modified with nanosilica. In the first stage of the research, the effects of nanosilica (NS) and silica fume (SF) on the hydration and compressive strength of cementitious composites were compared. In the second stage, four different types of cement mortars, containing an optimal dosage of NS, were produced. Two of them contained a normal weight aggregate (quartz or limestone), whilst two contained a heavy weight aggregate (barite or magnetite). Specimens without NS were produced for control purposes. The specimens were exposed to 300, 450, 600 and 800°C, with their post-heating properties – including thermal conductivity, specific heat, solvent absorption and cracking behavior – analyzed. The results show that NS exhibits significantly higher reactivity with cement than SF. NS accelerates the cement hydration process and contributes more significantly to the 28 and 365 day compressive strength of mortar, as compared to SF. The incorporation of NS in a composite substantially decreases the amount of CH in the mixture and leads to the production of additional C–S–H gel phase, which improves microstructure. The study also shows that NS contributes to a decrement in the thermal conductivity and density of mortar, both prior to and after heating. The incorporation of NS has a beneficial effect on decreasing the deterioration rate of mortars after heating, by decreasing absorption rate and the amount of cracks in in them.
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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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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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