Nanotechnologies in Construction: A Scientific Internet-Journal

Number 5, 2021

276-281
Integral quality indicators of waste concrete

Authors: Ayzenshtadt A.M., Danilov V.E., Drozdyuk T.A., Frolova M.A., Garamov G.A.

Abstract

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Introduction. Waste concrete is one of the main heavy construction waste having good recycling prospects with regard to rational nature management related to reducing the consumption of natural resources. However, the widespread introduction of waste concrete is hindered on the one hand by the variety of compositions and structures of recycled scrap, and on the other hand by the lack of quantitative criteria to choose the most rational area of its use (a binder component, coarse and fine aggregate,finely dispersed filler, etc.). Materials and methods. Case studies of experimental powders obtained by mechanical grinding from the concrete scrap of internal wall panels and floor slabs (heavy concrete) and external wall panels (light concrete) of a five-storey residential panel house built in 1979 in the Obozersky village, Arkhangelsk region, demonstrated the possibility of choosing the optimal secondary use of waste concrete fractions featuring residual compressive strength. The indicators of residual strength, grindability and contraction of mineral powders were used as optimization criteria. Results and discussions. The applicability of the mathematical model for calculating the raw material grindability index is shown. A criterion for grinding equipment selection is proposed to obtain powders with an extended active surface. Conclusions. Powders obtained from the fraction of waste light concrete featuring low strength properties and grindability by mechanical grinding to a specific surface area comparable to that of Portland cement used and having a higher value of contraction can be rationally used as a composite binder component. Concrete scrap fractions featuring by higher grindability and strength properties are optimally suited for crushed aggregate preparation in the concrete composite production process.

282-292
Arrangement of chemical elements in the three-dimensional matrix

Authors: Gusev B.V., Yin S.Y-L., Speransky A.A.

Abstract

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Number of views: 151

It is emphasized in the article that thanks to the discovery of D.I. Mendeleev and the Periodic Table of chemical elements existing for more than 150 years, as well as the international table IUPAC, chemistry has been actively developing and keeps developing. A new model for arranging chemical elements in the form of a three-dimensional matrix has been proposed. This makes it possible to predict new elements with the designation of nuclear masses and the electronic structure of shells. There have been developed new patterns according to the cyclicity (block structure) of horizontal rows and the structure of vertical groups and their physical conception have been specified.

293-305
Properties of Nano Engineered Concrete Subjected to Accelerated

Authors: Maher El-TairA.,El-Feky M.S., Mohsen Alaa, KohailM.

Abstract

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Number of views: 158

Introduction. Many research had worked on improving the performance of concrete subjected to severe environment and improve concrete corrosion resistance. Using nano-materials is one of the methods had been used recently to improve concrete properties. In this research, a comparison between the performance of nano-silica and nano-clay in enhancing the durability properties of concrete was investigated. Methods and Materials. The experimental program was carried out through examining water absorption, water permeability, rapid chloride penetration test, corrosion resistance, bond strength of steel rebar before and after subjected to corrosion, and finally microstructure test. Nano-silica and nano-clay were added at 1%, 3%, and 5% as a partial replacement by weight of cement. Results. Both nano-silica and nano-clay showed significant performance in reducing the permeability and porosity of concrete and improve corrosion resistance of concrete. For comparison, nano-clay had a significant impact than that of nano-silica on concrete properties; in which the water permeability resistance of nano-clay mixes was enhanced by 87% than that of the control mix, while for nano-silica, it was 51% only. The chloride ion penetration was reduced by 72% for nanoclay mixes, while in nano-silica was 28%. Discussion. Nano-clay had a significant effect than that of nano-silica on the concrete durability properties; the flat-shaped of nano-clay particles had improved the microstructure of the cement matrix through the damping effect, besides the filling effect through the microstructure of the matrix which reduces the chloride ion penetration and improves water absorption and permeability of concrete. Conclusion. The optimum percentage of nano-silica is 1% by weight of cement as a partial replacement of cement by weight. However, for nano-clay is 5%, which gives the best performance in improve the durability properties of concrete.

311-318
Inventions of scientists, engineers and specialists from different countries in the area of nanotechnologies. Part V.

Authors: Ivanov L.A., Xu L.D., Razumeev K.E., Feoktistova V.M., Prokopiev P.S.

Abstract

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Number of views: 143

Introduction. Advanced technologies impress people’s imagination demonstrating the latest achievements (materials,methods, systems, technologies, devices etc.) that dramatically change the world. This, first of all, concerns nanotechnological inventions designed by scientists, engineers and specialists from different countries. Main part. The article provides an abstract overview of inventions of scientists, engineers and specialists from different countries: Russia, USA, China, Belarus, Italy. The results of the creative activity of scientists, engineers and specialists, including inventions in the field of nanotechnology and nanomaterials allow, when introduced to industry, achieving a significant effect in construction, housing and communal services, and related sectors of the economy. For example, the invention «Protective coating and method of its application» relates to the field of protecting metals from corrosion. To obtain a protective coating, a composition containing an industrial oil with a powder of a phosphorusmodified copper-carbon nanocomposite is applied to the surface of an unalloyed steel and subjected to thermochemical activation by heating for 20 minutes at a temperature of 100–200°C. During the formation of the coating, strong donor-acceptor bonds of iron atoms with phosphorus, which are in the composition of the copper-carbon nanocomposite, are formed. In the course of experiments, it was found that heating samples with a coating of oil with the addition of a phosphorus-modified copper-carbon nanocomposite to 100–200°C increases the chemical activity of the nanocomposite, as a result of which a protective coating forms on the surface, which re uces the corrosion rate depending on the concentration of the modified metal-carbon nanocomposite.by 70–95%. The following inventions the field of nanotechnology are also of interest to specialists: a method for obtaining a nanostructured surface of a metal workpiece by laser treatment, a device for producing nanodispersed metal oxides, a method for producing a nanostructured composite material based on aluminum, a method for modifying the surfaces of plates of a brazed plate heat exchanger, etc. Conclusion. One of the most challenging tasks the economy of every country face is to increase industrial competitiveness through technological upgrade. From the side of the state and companies the principal object to control in this process are the people and enterprises dealing with introduction of inventions and new technologies.

319-327
Obtaining the retainer for waterproofing road bitumens

Authors: Boev E.V., Islamutdinova A.A., Aminova E.K.

Abstract

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Number of views: 113

Introduction. 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.