Nanotechnologies in Construction: A Scientific Internet-Journal @nanobuild-en
Статьи журнала - Nanotechnologies in Construction: A Scientific Internet-Journal
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Статья научная
Introduction. Research to improve the quality of foam concrete products through targeted control of technological processes of structure formation of cement-based compositions is relevant. The strength of foam concrete is significantly influenced by the adhesion strength of the hardened cement paste to the aggregate. This article discusses methods of chemical and mechanochemical activation of foam concrete filler with glyoxal-containing additives, interaction with hydration products of binders and increasing the strength of the contact zone. The quality of foam concrete can be improved by controlling the properties of the contact zone. Materials and methods. The study was conducted using standard test procedures specified in national standards. Results. With preliminary chemical and mechano-chemical exposure of the sand surface to glyoxal-containing additives and its subsequent introduction into the foam concrete mixture the grade of strength of foam concrete increases to B1 while maintaining the average density grade D500 in comparison with foam concrete of the control composition, while the shrinkage value decreases by 20–38.5% and thermal conductivity coefficient by 37%. Conclusion. The use of glyoxal-based additives in foam concrete mixtures by pre-activating the sand surface can improve the quality of cement foam concrete.
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Conversion of limestone-limestone mining waste by impregnation with polysulfide solutions
Статья научная
The data of studies on the effectiveness of impregnating Aquastat waste generated as a result of the development of limestone-shell rock deposits are presented. As a result of sand impregnation, the water absorption coefficient as a result underwent a significant decrease from 7 to 17 times, while the water absorption coefficient decreases from 32.5% for the initial to 1.9% impregnated. Even treatment with low concentrated (ρ = 1.17 g / cm3) calcium polysulfide solution made the water absorption coefficient to decrease to a value of 4.5%. As a result of impregnation of crushed stone from limestone-limestone with a solution of calcium polysulfide, the water absorption coefficient decreases from 25.0% for untreated to 5.2% for treated, and the decrease in the coefficient of water absorption is greater for concentrated solutions. It was found that a solution density of 1.24 g/cm3 is sufficient to reduce the water absorption coefficient to a value of 5.2%, the same as for a density value of 1.35 g/cm3. Comparison of the results of impregnation with «Aquastat» solution and sulfur melt showed that as a result of treatment with sulfur melt, the water absorption coefficient decreases by 13.3 and strength increases by 2 times, and as a result of impregnation with «Aquastat» solution decreases by 4.62%, strength increases by 1.35 times. Despite the high efficiency of sulfur melt processing, such treatment has drawbacks associated with the use of autoclave technology and high temperatures. The results of the modification of sand and crushed stone from shell rock by impregnating it with the «Aquastat» solution, a significant decrease in the water absorption parameter, an increase in compressive strength, revealed the possibility of using impregnated crushed stone as the layer material lying at the base of the road structures of local roads in the form of crushed stone and sand instead of the more expensive imported crushed stone.
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Creation of a composite material based on plant-based components. Nanotechnologies in construction
Статья научная
Introduction. The study is aimed at analyzing the possibility of creating a building composite material based on amylose and amylopectin with the introduction of crushed walnut shells as a filler. Materials and methods of research. To obtain the composite, the following components were used: distilled water, potato starch (NevaReaktiv, St. Petersburg, Russia), acetic acid 70% (NevaReaktiv, St. Petersburg, Russia), highly dispersed walnut shell powder. For this research, we used walnut shells of the Chandler variety (engrafted) collected form the Belgorod region. The composite was produced in several stages. At the first stage, a mixture of starch and walnut shells was added to distilled water, followed by a pre-prepared 9% acetic acid solution. The resulting mixture was thoroughly mixed, after which it was transferred to a stainless-steel bowl and subjected to heat treatment. The resulting mixture was then pressed with solid-phase compaction method at a pressure of 72 MPa. We studied the physical and mechanical characteristic of the resulting composite, its thermal properties, as well as the hydrophobic-hydrophilic balance of the surface. Results and discussion. The resulting composite has good strength characteristics. Flexural strength at break is σf = 25.85±2.51 MPa and σf = 28.44±5.71 MPa for filling 50% weight and 75% weight. Accordingly, they put it on a par with similar composites made from more conventional thermo- and thermoset polymers. The temperature limit for the composite material exploitation has been established, the upper of which can be considered the temperature at which the polymer matrix begins to soften – 103.1 °C. Conclusion. The results obtained are crucial for understanding the mechanisms involved in creating composite materials made entirely from plant components, utilizing, among other factors, agro-industrial waste.
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