Nanotechnologies in Construction: A Scientific Internet-Journal @nanobuild-en
Статьи журнала - Nanotechnologies in Construction: A Scientific Internet-Journal
Все статьи: 572
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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