Application of nanomaterials and nanotechnologies in construction. Рубрика в журнале - Nanotechnologies in Construction: A Scientific Internet-Journal
Modification of portland cement with nanoadditives
Статья научная
Introduction. Portland cement slurries (suspensions) used for well cementing have high water-cement ratios (0.45–0.6). They also contain a minimum amount of inert fillers, must have zero water separation and controlled hardening with a minimum time between the start and end of setting. Literature review. Most of the scientific work on the use of nano-additives in binder systems relates to the construction industry. Nanosilicon, nanotitanium, nanocarbonate, nanoclays, carbon nanofibers, etc. were widely used as modifiers of cement systems, which showed an increase in the strength characteristics of the resulting concretes. Literature review showed that there is a very wide range of concentrations of nanoadditives in cement systems from 0.001 to 10.0%. An increase in the strength of cement with high concentrations of additives in a number of publications is explained by a decrease in its capillary porosity due to clogging of the pore space. However, nanoadditives should not play the role of microfillers in the hardened stone. They should work in cement slurry at the stage of cement hydration and cement structure formation at concentrations less than 1.0%. Results and Discussion. The paper presents the results of experimental studies of the rheological properties and early strength of stone based on Portland cement with additives (0.01%) of nanocarbonate and nanoiron. The role of nanoadditives is to increase the rate of cement hydration by reducing the activation energy, and accelerating the dissolution of the solid phase in the liquid. Nanoadditives can be a “substrate” on which two-dimensional nuclei of a new phase are formed. The probability of the appearance of two-dimensional nuclei on the substrate is much higher than for the formation of three-dimensional nuclei of a new phase in the bulk of the solution. Conclusion. The results show an ambiguous effect of additives on the tested parameters, which indicates the need to optimize the amount of additives. One of the reasons for the ambiguity of the results may be high water-cement ratios, which reduce the likelihood of the formation of “constrained” conditions in cement slurries. At the same time, the effects of accelerated cement hydration are “levelled” and the number of contacts between hydration products is reduced.
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Nanocoatings in modern construction
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The review analyzes the state of the nanocoating market, shows main types of nanocoatings, as well as drivers and barriers to their development and application. Modern progress in the field of nanotechnology allows us to attribute nanocoating to high performance materials, the structure and properties of which can be “designed” according to specific functional criteria and the level of environmental impact. They present unique remarkable characteristics compared to conventional coating materials in construction industry. The government’s grandiose plans to commission new housing and road infrastructure, as well as ambitious projects to develop the Arctic and ensure national security, should lead to the growth of the industry as a whole, as well as to an increase in demand for more efficient, innovative building materials, including nanocoatings and nanopaints.
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Obtaining the retainer for waterproofing road bitumens
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Bitumen is a mixture of hydrocarbons and hetero-organic compounds. It is one of the most popular building materials today. Due to the growing consumption of bitumen for various purposes, the requirements for its quality characteristics are increasing, which prompts a comprehensive study of the physical and mechanical properties and methods of its modification. Currently, various additives are used, from inorganic materials to organic binders, including waste chemical, petrochemical and household industries. These additives create a nanodispersed structure inside the bitumen, which provides a change in the physical and mechanical properties in the required direction. Methods and materials. The work proposes a method for obtaining a fixer for waterproofing road bitumen based on nitrogen-containing organic compounds. The goal of research is to study the effect of the additive-derivative of triethylenediaminedicyan, which leads to the formation of a nanodispersed structure of bitumen of the “sol-gel” type, the quality indicators of which will meet the requirements of the new standard GOST 33133-2014 “Viscous road oil bitumen”. The object of the study is the bitumen production unit of workshop No. 14 of Gazprom neftekhimSalavat LLC, designed to produce commercial bitumen: oil road grades CB 90/130 in accordance with GOST 22245-90, used in road, civil and industrial construction as a binder and waterproofing material. Results and discussion. In the course of the study, the nature of the interaction and the effect of the modifier on the properties of bitumen, which ensure the production of nanostructured bitumen of the “sol-gel” type, were revealed. As a result of the study, a comparative assessment of the effect of the fixer on the properties of waterproofing bitumen revealed a significant improvement in physical and mechanical properties in comparison with bitumen grade CB 90/130. Conclusion. The obtained compound based on triethylenediaminedicyancan can be used as a fixing additive to road bitumen
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Peculiarities of the formation of silicon oxide films modified with metal nanoparticles
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Introduction. Silicon oxide film coatings have unique properties and are widely used in various industries, including construction. This paper presents the results on the preparation of polyalkylhydroxysiloxane liquid film in the presence of nanoscale particles of metallic bismuth. Methods and materials. Laser ablation method of metallic bismuth in aqueous medium was used to obtain bismuth nanoparticles. The surface of the target was treated with a laser beam at the workstation of an ytterbium pulsed fiber laser are discussed. The particle size and electrokinetic properties of colloidal bismuth sols were determined method by dynamic light scattering. After drying, Bi powder was added to polyalkylhydroxysiloxane liquid. Thin films cured under different heat treatment modes are applied to glass substrates by dipping. The resulting films were characterized by SEM, X-ray phase analysis, and FTIR spectroscopy. Results. In this work, the electrokinetic properties of colloidal bismuth sols are discussed. Laser ablation of a bismuth substrate leads to an increase in electrical conductivity and the appearance of a double electric layer in colloidal sols. The effect of the curing temperature on the properties of the coating is shown. It was found that the content of bismuth nanoparticles in the polyalkylhydroxysiloxane coating (3 wt.%) does not lead to the formation of crystalline phases. At the same time, the composition of the film and the mode of heat treatment affect the short-range order of molecular bonds. Increasing the content of bismuth nanoparticles in the coating of more than 10 wt.% leads to the appearance of microcrystalline phases of bismuth silicates in the system. Conclusion. The results obtained in the course of the study supplement the information about the production of bismuth nanoparticles by laser ablation and are of great importance in the practice of creating composite films.
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Production method of nanostructured wood-polymer composition with microwave application
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Introduction. Currently, wood-polymer compositions (WPC) are widely used in the national economy and construction. The composition of WPC varies widely depending on the further purpose. Improving the binding quality in the wood-polymer system is one of the promising areas for enhancing operational characteristics. Organic and inorganic substrates nanostructured with individual substances, including metal particles, are used as binding components. In the petrochemical industry, most high-capacity productions use catalysts based on active carriers like heavy metals when developing targeted products for various purposes. After several stages of regeneration, recovering these heavy metals becomes impossible. Consequently, spent catalysts accumulate in sedimentation tanks and sludge collectors, lacking an efficient method for disposal and secondary use. One of the components included in the composition of spent catalysts is chromium (+6), which belongs to carcinogenic metals. Numerous disposal methods are currently inadequate for neutralizing this metal on an industrial scale, which is of interest for research. Methods and materials. The study is aimed at converting carcinogenic chromium (+6) into non-carcinogenic chromium (+3) by ultrahigh frequency exposure (microwave), which will open up opportunities for its use as a chromium-containing nanocomplex binding a tree-polymer. Results and discussions. The ultrahigh-frequency effect on the mixture of wood-polymer composition and spent chromium (+6) causes an increase in the penetration depth of high–frequency waves, characterized by a uniform distribution of energy over the entire area of the composite, which is explained by the reduction of chromium (VI) oxide into chromium (III) oxide, and there is also a change in the color of the nanostructured wood-polymer composition (WP – compositions) from yellow to malachite. Conclusion. This study, which consists in the application of microwave exposure to the wood-nanoparticle-polymer system, confirms the receipt of a durable construction product and its use in the construction of roofs, facade boards, sidewalks, piers, port facilities, etc.
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Production of a nanostructured bitumen modifier in the reprocessing of automobile tires
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Introduction. Polymer-bitumen binders are innovative nano-binders for asphalt concrete pavement. Introduction of a polymer modifier improves the characteristics of bitumen and asphalt concrete. The use of waste tires rubber for bitumen modification is considered to be an environmentally friendly solution, but it is limited due to the poor cosite of rubber with bitumen. Various methods based on activation of the rubber surface, dispersion of rubber to nanosized particles, and thermochemical transformations of rubber into individual organic compounds are known to overcome this limitation. Methods and materials. The method of joint pyrolysis of rubber with oxygen-containing oil under pressure is proposed to be used for converting it into a nanostructural bitumen modifier. The resulting product is studied by the methods of thermogravimetry, NMR-spectroscopy, chromatomasspectrometry, scanning electron microscopy and solubility in toluene. Results and discussion. It has been established that during joint pyrolysis rubber undergoes devulcanization, cracking and dispersion to nanosized particles, and as a result the product becomes compatible with bitumen. Thermochemical reprocessing of waste automobile tires can be considered to be a promising method for the production of a nanostructured bitumen modifier. Conclusion. The use of thermochemical pressure treatment of waste tire rubber in the presence of oxygen-containing oil makes it possible to obtain a nanostructured product compatible with bitumen for further use of the resulting modifier in the production of asphalt concrete.
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Regulation of the aggregate stability for binary polymer-mineral dispersions
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Introduction. In the binary dispersed systems of different origins (mineral and polymer) with particles differing in size by an order of magnitude, heterocoagulation is observed. Regulation of the aggregate stability is crucial in controlling the properties of functional dispersed materials based on such mixed dispersions. This study focuses on the investigation of waterborne mono and binary dispersions of polyvinyl acetate, Portland cement, and chalk by means of static laser light scattering and optical microscopy. Materials and research methods. In order to investigate the action mechanism of the FF modifier based on phloroglucinol furfural oligomers as disperse phase we used chalk (CaCO3 – chalk dispersed technical MTD-2, LLC “Technostroy”, Kopanishchenskoe deposit), Portland cement CEM I 42.5N (JSC “Belgorod Cement”), and polyvinyl acetate (LLC “Kuban-Polymer”). Particle distribution and the aggregate stability of dispersions were studied with an Analysette 22 NanoTecplus device. The particle sizes were determined by optical microscopy with “Axio.Scope.A.1” microscope, and the adsorption of oligomers on the particles of dispersions was analyzed using a UV spectrometer (SPECORD UV). Results and discussion. It has been established that the phloroglucinol furfural modifier contributes to the stabilization of binary polymer-mineral dispersions. Integral and differential distribution curves of polymeric particles have been obtained in a wide range of 0.01–2100 μm. Research has shown the regularity of the modal diameter reduction of adsorption-modified particles with a transition from a narrow to a wider distribution with the absence of large coagulums. Conclusion. The hypothesis has been proposed that the adsorption-solvation factor of aggregate stability makes a significant contribution to the aggregate stability of binary polymer-mineral dispersions. The impact of this factor is different for mono-mineral and binary polymer-mineral dispersions and depends on the hydrophilicity of the surface, increases with the transition from mineral surface to the polymer surface as the Hamaker constant increases.
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Статья научная
Introduction. Phenols and petroleum products are common wastewater contaminants in many industries. Due to their persistence and toxicity in the natural environment, an efficient waste disposal technology is needed. Ozonation in the presence of heterogeneous catalysts is one of the advanced methods for treating wastewater from these toxicants. Since most catalysts are expensive, they are being sought on the basis of transition metals and their oxides, which have high activity and relatively low cost. In this regard, the Scientific and Educational Center for Innovative Technologies (SECIT) of USPTU carried out work on the search for an effective and affordable catalyst for the deep oxidation of phenol and petroleum products in wastewater under the influence of ozone. Methods and materials. To study catalytic ozonation, we used model waste water containing phenol and oil products at concentrations of 8 and 30 mg/dm3, respectively. Ozonation was carried out in the presence of fresh (1) and spent (2) NiO–MoO3 catalyst deposited in the form of a film on cylindrical Al2O3 granules weighing 0.5 – 2 g. Results. Optimal conditions of ozonation have been found (1), within 10 min of the decomposition process in its presence, COD decreased by 25% compared to the oxidation process with a catalyst (2), and by 40% compared to classical ozonolysis. It was found that the optimal loading of catalyst (1) is 1 g, duration is 35 min, pH = 8.5, temperature – 22 – 30оC, ozone dose – 5 g/dm3. Discussion. At catalyst dosages of less than 1 g/dm3, the low efficiency of removing phenol and hydrocarbons is probably due to a lack of the adsorption surface of the catalyst. Conclusion. The studied method of purification allows to reduce the content of phenol and oil products to the standard indicator of drinking water quality (0.001 and 0.05 mg/dm3, respectively), COD by 96% and solve the problem of the harmful effects of these toxicants on ecosystems.
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Статья научная
Introduction. Small innovative enterprises are able to solve the problems of technological support of the construction sector. A special place is occupied by enterprises created on the basis of the results of intellectual activity (RIA) of higher educational institutions. The activities of small companies created with the participation of universities have a number of advantages. The scientific and educational environment creates additional opportunities for small businesses in conducting research and development, as well as opens up access to human resources. An example of the commercialization of RIA is the technological developments based on nanomaterial of St Petersburg University enterprises in solving the problem of abandonment of orphan wells, which contribute to the pollution of groundwater. Methods and materials. Abandoned wells are abandoned according to “standard designs” that provide for the abandonment of only the wellbore limited by the inner diameter of the casing pipes, and do not contain technical solutions for the elimination of behind-the-casing flows. Results. An ownerless well, after its abandonment according to the “standard project”, continues to contaminate groundwater, but on a permanent basis, since repeated abandonment of such wells is practically impossible. Each such “abandoned” well is an officially created channel for groundwater contamination in the long term. Discussion. The article contains an analysis of the existing technology of abandonment of wells, including ownerless ones, as well as the justification of the futility of its use to eliminate sources of groundwater pollution. An alternative solution based on the use of modern nanomaterials is proposed. Conclusion. Examples of successful application of the proposed technology with the use of cemented nanomaterials for the liquidation of emergency wells in the North-West region are given. Based on the study, conclusions and recommendations are made.
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Introduction. The article discusses the current state of the possibilities to improve the efficiency of construction processes by using fibre-reinforced concrete in the construction of transport and utility tunnels, as well as other critical building structures. The authors present foreign experience with widespread use of fibre-reinforced concrete in transport construction, as well as few such cases for domestic practice. The inconsistency of domestic experience with the modern state of art has been noted. The main blockers in the development of the issue are under consideration, the theoretical approach and practical application are presented. Materials and methods. The principal aspects of the current approach to the quality indicators of fibre-reinforced concrete and the classification principles of fibre-reinforced concrete based on quality criteria, which are the basis for the normalization of material characteristics, are described. The continuity of domestic and European regulatory documents is shown. Results. Illustrated examples of the possibilities of an optimization approach to the selection of structural solutions in the design of transport construction facilities used in international practice are described. Conclusion. The argumentation in favor of technology development is shown. This opens up possibilities for significant cost reduction justified by a scientific approach. In conclusion, the authors provide recommendations on the general application of the promising material in the domestic practice.
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Wood-polymer nano-modified composite materials for construction purposes
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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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X-ray spectral methods for measuring the degree of ordering of carbon nanoparticles
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Methods for the quantitative assessment of the content of ordered structures in the products of synthesis of fulleroid materials based on the spectra of characteristic X-ray radiation and X-ray diffraction are considered. The introduction shows that the use of carbon fulleroid materials (fullerenes, fullerenols and their compounds, fulleroid nanoparticles) as modifiers of the properties of various structural materials and plasticizers of concrete mixes is currently one of the most rapidly developing areas in the field of nanotechnology in construction. Methods and materials. In this work, the following analytical control methods were used: scanning microscopy, local X-ray spectral analysis and X-ray diffractometry. The products of synthesis of fulleroid materials were studied: samples of fullerene-containing soot collected at different distances from the arc synthesis zone. Results. Raster images of the synthesis products with various magnifications are shown, as well as the X-ray fluorescence spectra and the elemental composition of the synthesis products. The X-ray phase analysis of the synthesis products was carried out. It is shown that the analysis of the amorphous component of the composition, which is one of the products of the yield, will make it possible to control the synthesis at each stage and under various conditions of its implementation. Analysis of a nonlinear dynamic system. To construct an attractor of a dynamic system, the correlation dimension, the dimension of the phase space and the fractal dimension of the process under study were calculated. The correlation dimension and the dimension of the phase space were calculated using the Takens’ method. The fractal dimension is calculated using the Hurst exponent. Conclusions. To study the dynamics of chemical reactions occurring during arc synthesis, the system of differential Rössler attractor is used. A solution to this system is obtained – Rössler attractor – an attracting set of trajectories in the phase space, which is identical in appearance to the process under study, which makes it possible to estimate, relying on attractors characteristic of each sample (synthesis material), at what stage the synthesis process occurs, and by making differential model, to organize the control to improve the quality of output products. Thus, the possibility of evaluating the efficiency of the synthesis of fulleroids used for the modification of building materials is demonstrated.
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