Information on the state and main trends of the cement market development in Russia in 2020 is provided. According to the results of 2020, 55.99 million tons of cement were produced in Russia (97.1% compared to the same period of the previous year). The fall peaked in April, when cement production fell by 17.6%, but later production volumes began to gradually recover. The main volume of cement produced in 2020 fell on the share of Portland cements without mineral additives, the volume of production of this product amounted to 34.51 million tons (61.6% of the total Russian cement output). According to the GS-Expert, in case of favorable development of the epidemiological situation in the country and the absence of new restrictions, the resumption of growth of the domestic economy and the preservation of a stable ruble exchange rate in 2021, the growth rate of cement production and consumption in the country will be about 3–5% compared to 2020, followed by a slowdown to 2–3% in 2022–2023.

A.A. SEMENOV, Candidate of Science (Engineering), General Director (This email address is being protected from spambots. You need JavaScript enabled to view it.)

LLC “GS-Expert” http://www.gs-expert.ru/

The dynamic building materials market poses challenges to increase the competitiveness of piece goods. This also fully applies to autoclaved pressed materials, the quality assurance of which still requires efforts on the part of manufacturers. The aim of this work was a comprehensive assessment of the effect of a highly dispersed active mineral modifier based on natural raw materials of various genesis on the properties of silicate bricks. Silicate and aluminosilicate rocks of crystalline and amorphous structure (sand, granite, silica clay, perlite) are used as raw materials for obtaining a modifier. The regularities of the influence of the type and concentration of the modifier on the physical and mechanical characteristics of the molding mixture, raw brick and finished silicate brick have been established. It is shown that the mineral modifier, regardless of the raw material component, has a high activity in relation to CaO and a high adsorption capacity, which leads to an increase in the raw brick strength and density, a decrease in porosity and water absorption. Increase in strength and frost resistance. The boundary concentrations (optimal dosage) of the mineral modifier instead of sand were determined in the silicate mixture in terms of solid matter, which is 10–15% depending on the type of raw material used. The structural features of the samples are shown, which determine the formation of a strong consolidated composite: the addition of a mineral modifier, regardless of its composition, ensures the formation of a polymineral polymorphic structural composite with a developed structure of a newly formed substance, characterized by good adhesion to the aggregate.

V.V. NELUBOVA¹, Candidate of sciences (Engineering),
V.V. STROKOVA¹, Doctor of sciences (Engineering);
A.L. POPOV², Candidate of sciences (Engineering)

¹ Belgorod State Technological University named after V.G. Shoukhov (46, Kostyukova street, Belgorod, 308012, Russian Federation)
² North-Eastern Federal University in Yakutsk (42, Kulakovskogo Street, Yakutsk, 677007, Russian Federation)

1. Goncharova M.A., Ivashkin A.N. Development of optimal compositions of silicate concrete using local raw materials. Stroitel’nye Materialy [Construction Materials]. 2016. No. 9, pp. 6–8. (In Russian).
2. Chernyshov E.M., Potamoshneva N.D. Manufacture of silicate autoclave materials using wastes of the enrichment of KMA banded iron formation. Stroitel’nye Materialy [Construction Materials]. 1992. No. 11, pp. 4–5. (In Russian).
3. Volodchenko A.N., Lesovik V.S. Prospects for the widening of the range of autoclaved silicate materials. Stroitel’nye Materialy [Construction Materials]. 2016. No. 9, pp. 34–37. (In Russian).
4. Kuznetsova G.V., Morozova N.N., Klokov V.V., Zigangaraeva S.R. Silicate brick and autoclaved gas concrete with the use of waste of own production. Stroitel’nye Materialy [Construction Materials]. 2016. No. 4, pp. 76–79. (In Russian).
5. Kotlyar V.D., Kozlov A.V., Zhivotkov O.I., Kozlov G.A. Calcium–silicate brick on the basis of microspheres and lime. Stroitel’nye Materialy [Construction Materials]. 2018. No. 9, pp. 17–21. (In Russian).
6. Khusainov A.K., Gurova E.V. The use of the ash CHP in the production of silicate brick. Tehnika i tehnologii stroitel’stva. 2019. No. 2 (18), pp. 41–45. (In Russian).
7. Kapustin F.L., Vishnevskii A.A., Ufimtsev V.M. The use of waste ash and slag mixture in the production of autoclaved gas concrete. Gidrotekhnicheskoe stroitel’stvo. 2017. No. 5, pp. 29–33. (In Russian).
8. Zimakova G.A., Solonina V.A., Zelig M.P., Orlov V.S. Role of aleuropelites in formation of properties of lime-silicate materials of autoclaved hardening. Stroitel’nye Materialy [Construction Materials]. 2018. No. 9, pp. 4–9. DOI: https://doi.org/10.31659/0585-430X-2018-763-9-4-9 (In Russian).
9. Dzhandullaeva M.S., Atakuziev T.A. Possibility of using heat-treated tuffite as hydraulically active additives in the production of silicate products. Khimicheskaya promyshlennost’. 2017. Vol. 94. No. 1, pp. 27–30. (In Russian).
10. Leont’ev S.V., Golubev V.A., Shamanov V.A., Kurzanov A.D., Yakovlev G.I., Hazeev D.R. Modification of the structure of heat-insulating autoclaved gas concrete by the dipersion of multi-layer carbon nanotubes. Stroitel’nye Materialy [Construction Ma-terials]. 2016. No. 1–2, pp. 76–83. (In Russian).
11. Kuznetsova G.V., Shinkarev A.A., Morozova N.N., Gazimov A.Z. Additives for direct technology of silicate brick production. Stroitel’nye Materialy [Construction Materials]. 2018. No. 9, pp. 12–16. DOI: https://doi.org/10.31659/0585-430X-2018-763-9-12-16 (In Russian).
12. Ovchinnikov A.A., Akimov A.V., Hozin R.R. Studies of physicomechanical and operational indicators of modified gas concrete. Informacionnaya sreda vuza. 2016. No. 1 (23), pp. 398–405. (In Russian).
13. Sumin A.V., Strokova V.V., Neljubova V.V., Eremen-ko S.A. Foam gas concrete with nanostructured modifier. Stroitel’nye Materialy [Construction Materials]. 2016. No. 1–2, pp. 70–75. (In Russian).
14. Neljubova V.V., Podgornyj I.I., Strokova V.V., Pal’shina Ju.V. Autoclaved aerated concrete with nanostructured aluminosilicate modifier. Stroitel’nye Materialy [Construction Materials]. 2016. No. 4, pp. 72–75. (In Russian).

The accumulation of plastic waste and the pollution of ecosystems with micro plastics has become a global problem of our time. The basic industry for the efficient utilization of plastic waste is the construction industry. When collecting and sorting waste, polyolefins and polyethylene terephthalate are most successfully selected, but when they are used in building compositions as fillers, their binding potential is not realized. We have production experience in processing polyolefin waste into polymer concrete products; however, the quality of the products is unstable, due to the lack of a regulatory framework and insufficient scientific justification for the selection of compositions and manufacturing technologies. The possibility of obtaining polymer sand concrete products using thermoplastic waste as binders is shown. Polymer sand samples based on a mixture of polyethylene terephthalate and polypropylene waste in a ratio of 95–80 to 5–20% by mass have a density of up to 2000 kg/m³, and, if compared with cement concrete, the compressive strength is not lower than class B12.5, tensile strength in bending is not lower than class Вtb6.8 with a variation coefficient of 30%, have higher impact strength. Manufacturing technology is of low-power consumption; products acquire tempering strength within an hour after manufacturing. Increased reproducibility of indicators of properties of polymer concrete based on thermoplastic waste remains an important technological challenge. The use of thermoplastic waste as binders in building compositions is a real way to solve the environmental problem of plastic pollution, corresponding to the concept of sustainable development and the principles of a circular economy.

N.N. FOMINA¹, Candidate of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.);
V.G. KHOZIN², Doctor of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.)

¹ Yuri Gagarin State Technical University of Saratov (77, Polirechnicheskaya Street, Saratov, 410054, Russian Federation)
² Kazan State University of Architecture and Engineering (1, Zelenaya Street, Kazan, 420043, Russian Federation)

1. Geyer R., Jambeck J., Law K.L. Production, use, and fate of all plastics ever made. Science Advances. 2017. Vol. 3. No. 7. DOI: https://doi.org/10.1126/sciadv.1700782.
2. Geyer R. Earth and Plastic. 2020. DOI: https://doi.org/10.11647/obp.0193.24.
3. Ruimin Q., Davey L.J., Zhen L., Qin L., Changrong Y. Behavior of microplastics and plastic film residues in the soil environment: A critical review. Science of The Total Environment. 2020. Vol. 703. DOI: 10.1016/j.scitotenv.2019.134722.
4. Xu Ch., Zhang B., Gu Ch., Shen Ch., Yin Sh., Aamir M., Li F. Are we underestimating the sources of microplastic pollution in terrestrial environment? Journal of Hazardous Materials. 2020. Vol. 400. DOI: https://doi.org/10.1016/j.jhazmat.2020.123228.
5. Horton A.A., Walton A., Spurgeon D.J., Lahive E., Svendsen C. Microplastics in freshwater and terrestrial environments: Evaluating the current understanding to identify the knowledge gaps and future research priorities. Science of The Total Environment. 2017. Vol. 586. pp. 127–141. DOI: https://doi.org/10.1016/j.scitotenv.2017.01.190.
6. Packaging market. State, trends and innovations. Polimernye materialy. 2020. No. 11, pp. 43–50. (In Russian).
7. International conferences “PETF-2020” and “Recycling of polymers-2020”. Polimernye materialy. 2020. No. 5, pp. 38–42. (In Russian).
8. Rzayev K.V. Current state and trends of the market for processing plastic waste in Russia. Polimernye materialy. 2020. No. 8, pp. 4–10. (In Russian).
9. Faitelson V.A., Tabachnik L.B. Polymer concretes on a thermoplastic binder. Stroitel’nye Materialy [Construction Materials]. 1994. No. 9. pp. 21–22. (In Russian)
10. Davaasenge S.S., Burenina O.N. Technology of polymer waste processing into building materials. Izvestiya Samarskogo nauchnogo tsentra Rossiiskoi akademii nauk. 2009. Vol. 11. No. 5 (2), pp. 276–278. (In Russian).
11. Antsupov Yu.A., Lukasik V.A. Manufacturing of finishing tiles based on polymer waste. Stroitel’nye Materialy [Construction Materials]. 2004. No. 1. pp. 44–45. (In Russian).
12. Kumi-Larbi Jnr Al., Yunana D., Kamsouloum P. , Webster M., Wilson D.C., Cheeseman Ch. Recycling waste plastics in developing countries: Use of low-density polyethylene water sachets to form plastic bonded sand blocks. Waste Management. 2018. Vol. 80, pp. 112–118. DOI: https://doi.org/10.1016/j.wasman.2018.09.003
13. Dalhat M.A., Al-Abdul Wahhab H.I. Cement-less and asphalt-less concrete bounded by recycled plastic. Construction and Building Materials. 2016. Vol. 119, pp. 206–214. DOI: https://doi.org/10.1016/j.conbuildmat.2016.05.010
14. Slieptsova I.,SavchenkoB., Sova N.,Slieptsov A. Polymer sand composites based on the mixed and heavily contaminated thermoplastic waste. IOP Conference Series: Materials Science and Engineering. 2016. 111. 012027. DOI: https://doi.org/10.1088/1757-899X/111/1/012027.
15. Fomina N.N., Ivaschenko Yu.G., Polyansky M.M., Pavlova I.L. Construction compositions based on integrated binding of thermoplastic waste. IOP Conference Series: Materials Science and Engineering. 2018. Vol. 365. Iss. 3. DOI: https://doi.org/10.1088/1757-899X/365/3/032018.
16. Fomina N.N., Polyansky M.M. Components of solid municipal waste in construction compositions. IOP Conference Series: Earth and environmental Science. 2019. Vol. 337. Iss. 1. DOI: https://doi.org/10.1088/1755-1315/337/1/012022.
17. Nisticо R. Polyethylene terephthalate (PET) in the packaging industry. Polymer Testing. 2020. Vol. 90. https://doi.org/10.1016/j.polymertesting.2020.106707.
18. Patent RF 2623754. Smes’ dlya polucheniya kompozitsionnykh stroitel’nykh materialov [Mix for the composite building materials production]. Ivashchenko Yu.G., Fomina N.N., Polyansky M.M. Declared 03.29.2016. Published 29.06.2017. Bulletin No. 19. (In Russian).

In construction practice, along with other technologies, methods of external reinforcement with polymer composite materials are widely used to strengthen structures. The authors developed modified epoxy-based adhesive binders to use in the construction of external reinforcement systems for building structures. The introduction of epoxy resin into the composition of multilayer CNTs in an amount from 0.001 to 0.01 wt. h. per 100 wt. h. leads to an increase in the adhesive characteristics of the adhesive, tensile and bending strength, while maintaining manufacturability. The temperature-time dependence of the creep of a reinforced concrete beam reinforced with an external reinforcement system based on the developed adhesive binder and carbon fabric is studied, and the obtained indicators are compared with an industrial analog. The constructed creep curves indicate the identical nature of the deformation process under loading at each temperature stage. At the same time, for a reinforced concrete beam strengthened with carbon fabric and RecARM-B glue, less deformability was noted in the studied temperature ranges.

I.A. STAROVOITOVA¹, Candidate of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.);
A.R. SHAKIROV², Engineer (This email address is being protected from spambots. You need JavaScript enabled to view it.);
E.S. ZYKOVA¹, Engineer (This email address is being protected from spambots. You need JavaScript enabled to view it.),
A.N. SEMENOV¹, Engineer (This email address is being protected from spambots. You need JavaScript enabled to view it.),
A.M. SULEIMANOV², Doctor of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.)

¹ LLC «Scientific Production Firm (SPF) «RECON» (100, build 7, Technopolis «Himgrad», Vosstaniya Street, Kazan, 420033, Russian Federation)
² Kazan State University of Architecture and Engineering (1, Zelenaya Street, Kazan, 420043, Russian Federation)

1. Shilin A.A., Pshenichnyi V.A., Kartuzov D.V. Vneshnee armirovanie zhelezobetonnykh konstrukczij kompoziczionnymi materialami [External reinforcement of reinforced concrete structures with composite materials]. Moscow: Stroyizdat. 2007. 179 p.
2. Evdokimov A.A., Imametdinov E.Sh., Malakhovskii S.S. Reinforcement of concrete building structures with structural carbon fiber reinforcement system. Trudy VIAM. 2020. No. 10 (92), pp. 73–80. (In Russian). DOI: https://doi.org/10.18577/2307-6046-2020-0-10-73-80
3. Rubin O.D., Lisichkin S.E., Frolov K.E. Results of experimental studies of reinforced concrete structures of hydraulic structures reinforced with carbon belts under the action of a bending moment. Stroitel’naya mekhanika inzhenernykh konstruktsii i sooruzhenii. 2016. No. 6, pp. 58–63. (In Russian).
4. Pellegrino C., Giacomin G., Perlo R.A. Experimental investigation on existing precast PRC elements strengthened with cementitious composites. Alternativas. 2016. Vol. 17. No. 3, pp. 65–69. DOI: http://dx.doi.org/10.23878/alternativas.v17i3.214
5. Nikoloutsopoulos N., Passa D., Gavela S., Sotiropoulou A. Comparison of shear strengthening techniques of reinforced concrete beams with carbon fibre reinforced polymers (CFRPs). Procedia Structural Integrity. 2018. Vol. 10, pp. 141–147. DOI: https://doi.org/10.1016/j.prostr.2018.09.021
6. Gribniak V., Pui-Lam Ng, Tamulenas V., Misiunaite I., Norkus A., Šapalas A. Strengthening of fibre reinforced concrete elements: synergy of the fibres and external sheet. Sustainability (MDPI). 2019. No. 11, pp. 1–13. DOI: http://dx.doi.org/10.3390/su11164456
7. Chursova L.V., Raskutin A.E., Gurevich Ya.M., Panina N.N. Cold-cured binder for the construction industry. Klei. Germetiki. Tekhnologii. 2012. No. 5, pp. 40–44. (In Russian).
8. Bichaev M.I. Investigation of the effect of natural galloisite nanotubes on the adhesion in the structural reinforcement system. Perspektivy nauki. 2019. No. 6 (119), pp. 116–120. (In Russian).
9. Selivanova E.O., Smerdov D.N. Experimental studies of creeping in composite materials that strengthen bent reinforced concrete elements. Akademicheskii vestnik URALNIIPROEKT RAASN. 2017. No. 2 (33), pp. 95–99. (In Russian).
10. Starovojtova I.A., Semjonov A.N., Zykova E.S., Hozin V.G., Sulejmanov A.M. Modified glue bin-ders for systems of external reinforcement of buil-ding structures. Part 1. Requirements for glues. Technological characteristics. Stroitel’nye Materialy [Construction Materials]. 2017. No. 11, pp. 50–54. (In Russian).
11. Sulejmanov A.M., Zykova E.S., Starovojtova I.A., Semjonov A.N. Modified glue binders for systems of external reinforcement of building structures Part 2. Physical and mechanical characteristics of glue. Stroitel’nye Materialy [Construction Materials]. 2017. No. 12, pp. 64–67. (In Russian).
12. Shakirov A.R., Pichkalev A.A., Suleimanov A.M. Development of a method for assessing the creeping of reinforced concrete beams reinforced with external reinforcement systems by the method of temperature-time analogy. International Scientific and Technical Conference “Durability, Strength and Fracture Mechanics of Building Materials and Structures: Materials of the XI Academic Readings of the RAASN”. Saransk. 2020, pp. 366–374. (In Russian).

Possibility of connection between molecular and structural mechanics of cement composites based on brand of Portland cement PC 500 D0 Н of cement plant JSC “Yakutcement” (С₃А = 6,98%, normal consistency of a cement paste = 26,25%) and graphene oxide suspension prepared in accordance with the Ammosov North-Eastern Federal University (NEFU) “Graphene technologies” laboratory production procedures is investigated. For developing a forecasting technique theory, a scheme for averaging the interatomic bonds properties to obtain the stress-strain characteristics of a cement with graphene oxide sheets with further homogenization and calculation of the cement composite macromodel using the finite element method was developed. To determine the convergence, Ansys 2020 R1 software and empirical results of previously conducted experiments of the NEFU Department of Industrial and Civil Engineering were used. It was found that the homogenized model has a tensile strength of 48.8 MPa, and the actual samples have a compressive strength of 58 to 62 MPa. Thus, this forecasting theory requires significant refinement and verification on empirical data. To carry out such research, it is necessary to create an interdisciplinary universal scientific group from among post-graduate students of the Chemistry, Mathematics, and Construction Materials Departments.

A.P. SCRYABIN, Master (This email address is being protected from spambots. You need JavaScript enabled to view it.),
G.D. FEDOROVA, Candidate of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.)

North-Eastern Federal University in Yakutsk (58, Belinskogo Street, Yakutsk, 677000, Russian Federation)

1. Dreyer D.R., Park S., Bielawski C.W., Ruoff R.S. The chemistry of graphene oxide. Chemical Society Review. 2010. Vol. 39, рp. 228–240. DOI: 10.1039/b917103g
2. Ovid’ko I.A. Mechanical properties of graphene. Reviews on Advanced Materials Science. 2013. Vol. 34. No. 1, pp. 1–11. http://www.ipme.ru/e-journals/RAMS/no_13413/01_13413_ovidko.pdf
3. Kim Y., Lee, J., Yeom M.S., Shin J.W. and etc. Strengthening effect of single-atomic-layer graphene in metal-graphene nanolayered composites. Nature Communications. 2013. No. 4. http://dx.doi.org/10.1038/ncomms3114
4. Bartolucci S.F., Paras J., Rafiee M.A. and etc. Graphene-aluminum composites. Materials Science and Engineering: A. 2011. Vol. 528, pp. 7933–7937. http://dx.doi.org/10.1016/j.msea.2011.07.043
5. Wang J., Li Z., Fan G., Pang H., Chen Z. and Zhang D. Reinforcement with graphene nanosheets in aluminum matrix composites. Scripta Materialia. 2012. Vol. 66, pp. 594–597. http://dx.doi.org/10.1016/j.scriptamat.2012.01.012
6. Koltsova T.S., Nasibulina L.I., Anoshkin I.V. and etc. New hybrid copper composite materials based on carbon nanostructures. Journal of Materials Science and Engineering: B. 2012. No. 2, pp. 240–246.
7. Fedorova G.D., Baishev K.F., Scryabin A.P. Graphene oxide as a promising nanomaterial for cement. Nauchnoe obozrenie. 2017. No. 12, pp. 36–41. (In Russian).
8. Fedorova G.D., Alexandrov G.N., Scryabin A.P., Baishev K.F. Influence of grapheme oxide on compressive strength of cement paste. Stroitel’nye Materialy [Construction Materials]. 2018. No. 1–2, pp. 11–17. DOI: https://doi.org/10.31659/0585-430X-2018-756-1-2-11-17
9. Fedorova G.D., Skriabin A.P., Aleksandrov G.N. The study of the influence of graphene oxide on the strength of cement stone using river sand. Stroitel’nye Materialy [Construction Materials]. 2019. No. 1–2, pp. 16–22. DOI: https://doi.org/10.31659/0585-430X-2019-767-1-2-16-22
10. Fedorova G.D., Aleksandrov G.N., Scryabin A.P. Activa-tion of structure-forming properties of graphene oxide in cement composites. Stroitel’nye Materialy [Construction Materials]. 2020. No. 1–2, pp. 17–23. DOI: https://doi.org/10.31659/0585-430X-2020-778-1-2-17-23
11. Peng Hui, Ge Yaping, Cai C.S. etc. Mechanical properties and microstructure of grapheme oxide cement-based composites. Construction and Building Materials. 2019. Vol. 194, pp. 102–109. https://doi. org/10.1016/j.conbuildmat.2018.10.234
12. Wu-Jian Long, Jing-Jie Wei, Feng Xing etc. Enhanced dynamic mechanical properties of cement paste modified with graphene oxide nanosheets and its reinforcing mechanism. Cement and Concrete Composites. 2018. Vol. 93, pp. 127–139. https://doi. org/10.1016/j.cemconcomp.2018.07.001
13. Zhao Li, Guo Xinli, Liu Yuanyuan, Zhao Yuhong etc. Hydration kinetics, pore structure, 3D network calcium silicate hydrate, and mechanical behavior of graphene oxide reinforced cement composites. Construction and Building Materials. 2018. Vol. 190, pp. 150–163. https://doi.org/10.1016/j. conbuildmat.2018.09.105
14. Nasedkin A.V. Finite element homogenization of nanostructured piezoelectric composites with interface phase boundaries. Materials of Xth All-Russian conference on mechanics of deformable solid body. Samara: SSTU. 2017. Vol. 2, pp. 98–101. (In Russian).
15. Sokolov A.P., Pershin A. Ya., Kozov A.V., Kirillov N.D. Homogenization of multilevel multicomponent heterogeneous structures for determining the physical and mechanical characteristics of composites. Physical Mesomechanics. 2018. Vol. 21. No. 5, pp. 90–107. (In Russian)
16. Semenov B.N. Finite-element models of mechanical characteristics of “(nano)metal-graphene” nanocomposites. Materials Physics and Mechanics. 2017. Vol. 30. No. 1, pp. 86–92. (In Russian).
17. Fedorova G.D., Alexandrov G.N., Smagulova S.A. The study of grapheme oxide use in cement systems. Stroitel’nye Materialy [Construction Materials]. 2016. No. 1–2, pp. 21–26.
18. Shenghua Lv, Yujuan Ma, Chaochao Qiu, Ting Sun, Jingjing Liu, Qingfang Zhou. Effect of graphene oxide nanosheets of microstructure and mechanical properties of cement composites. Construction and Building Materials. 2013. Vol. 49, pp. 121–127. https://doi.org/10.1016/j. conbuildmat.2013.08.022
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The subject of this research is a multicriteria analysis of the results of studies on the use of graphene oxide (GO) as a modifying additive for cement systems, the assessment of the efficiency and prospects of its use in the composition of cement concrete. Collected publications and empirical material are summarized and structured according to the following criteria: bibliometric indicators of publications over a ten-year period, the type of carbon nanomaterial, its properties both in the form of a starting material and as a raw material for the synthesis of GO; type of binder and functional additives; a method for stabilization, introduction and distribution of GO in a concrete mixture; controlled parameters and physical and mechanical properties of concrete. It is shown that in most of the considered studies GO nanosheets are synthesized by chemical separation according to the Hammers method. In order to increase the efficiency of dispersion and distribution of GO in a concrete mixture, the complex methods are used with a different sequence of introduction of components and physical and mechanical effects, including preliminary stabilization of carbon nanomaterial together with a superplasticizer, microfillers of various compositions, morphostructure and functional purpose (silica fume, ash, fiber, etc.) and ultrasonic processing (in a neutral or alkaline solution), as well as mechanical mixing. In addition, generalized versions of the mechanism of interaction between GO and individual components of the concrete mixture, its effect on the processes of structure formation of the modified cement stone and the physical and mechanical properties of concrete are presented.

V.V. STROKOVA¹, Doctor of Science (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
S.K. LAKETICH¹, postgraduate student (This email address is being protected from spambots. You need JavaScript enabled to view it.),
V.V. NELUBOVA¹, Candidate of Science (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.);
ZHENGMAO YE², Doctor of Science (This email address is being protected from spambots. You need JavaScript enabled to view it.)

¹ Belgorod State Technological University named after V.G. Shukhov (46, Kostyukova Street, Belgorod, 308012, Russian Federation)
² School of Materials Science and Engineering, University of Jinan (336, Nanxin Zhuang West Road, Jinan, Shandong, 250022, China)

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97. Baoguo Han, Qiaofeng Zheng, Shengwei Sun, Sufen Dong, Liqing Zhang, Xun Yu, Jinping Ou. Enhancing mechanisms of multi-layer graphenes to cementitious composites. Composites Part A: Applied Science and Manufacturing. 2017. Vol. 101, pp. 143–150. https://doi.org/10.1016/j.compositesa.2017.06.016
98. Sungjin Park, Kyoung-Seok Lee, Gulay Bozoklu, Weiwei Cai, Son Binh T. Nguyen, and Rodney S. Ruoff. Graphene oxide papers modified by divalent ions–enhancing mechanical properties via chemical cross-linking. ACS Nano. 2018. Vol. 2, Iss. 3, pp. 572–578. https://doi.org/10.1021/nn700349a
99. Lei Wu, Lin Liu, Bin Gao, Rafael Muñoz-Carpena, Ming Zhang, Hao Chen, Zuhao Zhou, Hao Wang. Aggregation kinetics of graphene oxides in aqueous solutions: experiments, mechanisms, and modeling. Langmuir. 2013. Vol. 29, Iss. 49, pp. 15174–15181. https://doi.org/10.1021/la404134x
100. Xiangyu Li, Chenyang Li, Yanming Liu, Shu Jian Chen, C.M. Wang, Jay G. Sanjayan & Wen Hui Duan. Improvement of mechanical properties by incorporating graphene oxide into cement mortar. Mechanics of Advanced Materials and Structures. 2018. Vol. 25, Iss. 15–16: Special Issue of the Mechanics of Advanced Materials and Structures, Honoring Professor J.N. Reddy on his 70th Birthday, pp. 1313–1322. https://doi.org/10.1080/15376494.2016.1218226
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The article presents the results of research on the production of composite binders using Portland cement and fly ash. The composite binder is produced by co-grinding of Portland cement and fly ash. The carbon nanomaterial was used, obtained by the plasma-chemical method on high production apparatus to modify the composite binder and aerated concrete on its basis. The modified carbon nanomaterial obtained by adding Portland cement to the plasma-chemical synthesis process was used in the study. Replacing a part of Portland cement with fly ash in a composite binder contributes to the additional formation of calcium hydrosilicates due to the binding of portlandite. The use of carbon nanomaterial increases the strength of both the ordinary Portland cement and the composite binder. Infrared spectroscopic data on cement and composite binder indicate additional formation of calcium hydrosilicates when fly ash is used. Compositions of non-autoclaved aerated concrete with the use of a composite binder and carbon nanomaterial with improved physical and mechanical properties have been investigated. Indicators of strength, thermal conductivity and shrinkage during drying of aerated concrete compositions have been determined. With the use of electron microscopic analysis, a change in the structure of the porosity of aerated concrete is shown when using a composite binder with fly ash and carbon nanomaterial. A quantitative assessment of the porosity of aerated concrete was carried out, which proves the change in the size and uniformity of the pore distribution.

S.A. LKHASARANOV, Candidate of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
L.A. URKHANOVA, Doctor of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
N.N. SMIRNYAGINA, Doctor of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
K.Kh. NAZAROVA, Еngineer (This email address is being protected from spambots. You need JavaScript enabled to view it.)

East Siberia State University of Technology and Management (40B, Klyuchevskaya Street, Ulan-Ude, 670013, Russian Federation)

1. Bazhenov Yu. M., Aleksandrova O.V., Nguyen Duc Vinh Quang, Bulgakov B.I., Larsen O.A., Gal’tse-va N.A., Golotenko D.S. High-performance concrete produced with locally available materials in Vietnam. Stroitel’nye Materialy [Construction Materials]. 2020. No. 3, pp. 32–38. (In Russian). DOI: https://doi.org/10.31659/0585-430X-2020-779-3-32-3
2. Lesovik V.S., Absimetov M.V., Elistratkin M.Yu., Pospelova M.A., Shatalova S.V. To the question of studying the peculiarities of structure formation of composite binders for non-autoclave aerated concrete. Stroitel’nye materialy i izdelija. 2019. Vol. 2. No. 3, pp. 41–47. (In Russian).
3. Krasinikova N.M., Kirillova E.V., Khozin V.G. Reuse of concrete waste as input products for cement concretes. Stroitel’nye Materialy [Construction Materials]. 2020. No. 1–2, pp. 56–65. (In Russian). DOI: https://doi.org/10.31659/0585-430X-2020-778-1-2-56-65
4. Fediuk R., Baranov A., Mosaberpanah M., Lesovik V. Link of self-compacting fiber concrete behaviors to composite binders and superplasticizer. Journal of Advanced Concrete Technology. 2020. Vol. 18. No. 3. pp. 67–82. DOI: 10.3151/jact.18.54
5. Toturbiev B.D., Mamaev S.A., Toturbiev A.B. Composite binders from industrial waste. Geologija i geofizika Juga Rossii. 2019. Vol. 9. No. 4, pp. 140–148. DOI: 10.23671/VNC.2019.4.44539 (In Russian).
6. Fedorova G.D., Skriabin A.P., Aleksandrov G.N. The study of the influence of graphene oxide on the strength of cement stone using river sand. Stroitel’nye Materialy [Construction Materials]. 2019. No. 1–2, pp. 16–22. (In Russian). DOI: https://doi.org/10.31659/0585-430X-2019-767-1-2-16-22
7. Nelyubova V.V., Podgorny I.I., Strokova V.V., Palshina Yu.V. Autoclaved aerated concrete with a nanostructured modifier of aluminosilicate composition. Stroitel’nye Materialy [Construction Materials]. 2016. No. 4, pp. 72–75. (In Russian).
8. Leontiev S.V., Golubev V.A., Shamanov V.A., Kurzanov A.D., Yakovlev G.I., Khazeev D.R. Modification of the structure of heat-insulating autoclaved aerated concrete by dispersion of multilayer carbon nanotubes. Stroitel’nye Materialy [Construction Materials]. 2016. No. 1–2, pp. 76–83. (In Russian).
9. Chernyshov E.M., Artamonova O.V., Slavcheva G.S. Nanomodification of cement composites at the technological stage of the life cycle. Nanotekhnologii v stroitel’stve. 2020. Vol. 12. No. 3, pp. 130–139. DOI: 10.15828/2075-8545-2020-12-3-130-139. (In Russian).
10. Gusev B.V., Kudryavtseva V.D., Potapova V.A. Concretes with nano-additive from fired secondary concrete. Nanotekhnologii v stroitel’stve. 2020. Vol. 12. No. 5, pp. 245–249. DOI: 10.15828/2075-8545-2020-12-5-245-249 (In Russian).
11. Yakovlev G.I., Skripkiunas G., Polianskich, I.S., Lahayne O., Eberhardsteiner J., Urkhanova L.A., Pudov I.A., Sychugov S.V., Karpova E., Sen’kov S.A. Modification of cement matrix using carbon nanotube dispersions and nanosilica. Procedia Engineering. 2017. Vol. 172, pp. 1261–1269. DOI: 10.1016/j.proeng.2017.02.148
12. Butters V., Kowald T., Mahjoori M., Trettin R. Surface modified carbon nanotubes for an enhanced interaction with cement based binders. nanotechnology in construction. Proceedings of NICOM5. Springer, Cham. 2015,pp. 253–258. https://doi.org/10.1007/978-3-319-17088-6_32
13. Tokarev Yu.V., Volkov M.A., Ageev A.V., Kuzmina N.V., Grakhov V.P., Yakovlev G.I., Khazeev D.R. Estimation of efficiency of applying aqueous dispersion of carbon particles in anhydrite binder. Stroitel’nye Materialy [Construction Materials]. 2020. No. 1–2, pp. 24–35. (In Russian). DOI: https://doi.org/10.31659/0585-430X-2020-778-1-2-24-35
14. Danoglidis P.A., Falara M.G., Maglohianni M. Scalable processing of cement composites reinforced with carbon nanotubes (CNT) and carbon nanofibers (CNF). Nano-tekhnologii v stroitel’stve. 2019. Vol. 11. No. 1, pp. 20–27. DOI: 10.15828/2075-8545-2019-11-1-20-27 (In Russian).
15. Danoglidis P.A., Konsta-Gdoutos M.S., Gdoutos E., Shah S.P. Strength, energy absorption capability and self-sensing properties of multifunctional carbon nanotube reinforced mortars. Construction and Building Materials. 2016. Vol. 120, pp. 265–274. https://doi.org/10.1016/j.conbuildmat.2016.05.049
16. Semenov A.P., Smirnyagina N.N., Tsyrenov B.O., Dasheev D.E., Khaltarov Z.M. Plasma-chemical synthesis of carbon nanotubes and fullerenes to create frost-resistant composite building materials. Journal of Physics: Conference Series. 2017. Vol. 830. No. 1, pp. 1–5. DOI: 10.1088/1742-6596/830/1/012123
17. Suleimanova L.A., Pogorelova I.A., Suleimanov K.A. Generalized analysis of the nature of the pore structure of non-autoclaved aerated concrete on composite binders. Vestnik Belgorodskogo gosudarstvennogo tehnologicheskogo universiteta im. V.G. Shuhova. 2016. No. 3, pp. 75–79. (In Russian).

The article presents the results of research on the modification of cement stone with microadditives of inorganic salts, such as CaCl₂, Ca(NO₃)₂, CaSO₄ and CuSO₄. The dosage of the 2% salt solution varied from 0.2 to 1%, while the dry salt consumption was from 0.004 to 0.02% of the cement weight. It was found that all investigated additives in the dosage range of 0.2–1 wt. %, counting on 2% salt solution, are accelerators of cement hardening and modifiers that increase its strength. Compressive strength of cement stone with additives at all times of hardening is higher than that of control samples. The maximum strength values were shown by samples of cement stone at the age of 28 days of hardening with the addition of CaSO₄ and Ca(NO₃)₂ – 85 MPa. For the salts CaCl₂ and CuSO₄, the compressive strength was 82.5 MPa and 68.8 MPa, respectively. It has been proven that an increase in the strength of a cement stone with microadditives of inorganic salts occurs in the early stages of hardening – 3, 7 days. The rate of strength gain of the cement stone reached 92–94% by 7 days of hardening in relation to the strength of the cement stone at 28 days of hardening. The mechanism of cement hydration with microadditives of inorganic salts is proposed

L.A. URKHANOVA, Doctor of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
P.V. BEREZOVSKY, Еngineer (This email address is being protected from spambots. You need JavaScript enabled to view it.),
N.V. ARKHINCHEEVA, Candidate of Sciences (Chemistry)

East Siberia State University of Technology and Management (40B, Klyuchevskaya Street, Ulan-Ude, 670013, Russian Federation)

1. Bazhenov Yu.M. Tekhnologiya betona [Concrete technology]. Moscow: ASV. 2002. 500 p.
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3. Ramachandran V.S., Feldman R.F., Collepardi M. et al. Dobavki v beton: spravochnoe posobie pod redaktsiei S.S. Ramachandrana [Additives to concrete: a reference manual edited by S.S. Ramachandran: translated from English]. Moscow: Stroyizdat. 1988. 575 p.
4. Guidelines for the use of chemical additives to concrete / NIIZhB Gosstroy of the USSR. Moscow: Stroyizdat, 1975.
5. Batrakov V.G. Modifitsirovannye betony. Teoriya i praktika [Modified concrete. Theory and practice]. Moscow: Tekhnoproekt. 1998. 768 p.
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9. Gonchikova E.V., Arkhincheeva N.V., Dorzhieva E.V. Sodium silicate binders and materials based on them. Stroitel’nye Materialy [Construction Materials]. 2010. No. 11, pp. 42–43. (In Russian).
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The article presents the results of the investigation on the influence of active mineral additives on the processes of structure formation of gypsum binders. Portland cement and nanosilica, previously treated with ultrasound for 3 minutes in an aqueous medium with plasticizer, were used as components of the complex mineral additive. The average particle size of nanosilica was 0.025 μm. The main component of the additive was silicon dioxide. It was found out that the introduction of the gypsum binder modifier, consisting of Portland cement and nanosilica, increased the strength of gypsum compositions up to 40%. The activated complex additive improved the physical and mechanical properties of the material, both at the stage of hydration and during the hardening of the composition. In this case, an increase in the density of gypsum stone can be caused by an increase in the dispersion level of the silicate additive, particles of which act as crystallization centers, and also have greater activity of chemical interaction with the alkaline component, compared to the untreated additive. The introduction of Portland cement and activated nanosilica lead to the change in the composition of the matrix, which was characterized by increased density and strength. This happened due to the development of new formations in the structure of the stone, that were based on calcium silicate hydrates and bonded gypsum crystalline hydrates into blocks, filling the pore space of the material. The formation of new hydration products in the composition of the gypsum matrix was confirmed by physical and chemical analysis methods, including IR spectral and differential thermal analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy.

М.D. BATOVA¹, Master student (This email address is being protected from spambots. You need JavaScript enabled to view it.),
Yu.А. SEMENOVA¹, Master student (This email address is being protected from spambots. You need JavaScript enabled to view it.),
А.F. GORDINA¹, Candidate of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
G.I. YAKOVLEV¹, Doctor of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.);
А.E.М.М. ELREFAI², Candidate of Sciences (Engineering), Associate professor (This email address is being protected from spambots. You need JavaScript enabled to view it.);
Z.S. SAIDOVA¹, Master (Graduate student) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
D.R. KHAZEEV¹, Candidate of Sciences (Engineering)

¹ Kalashnikov Izhevsk State Technical University (7, Studencheskaya Street, Izhevsk, 426000, IRussian Federation)
² Egyptian-Russian University (11829, Cairo-Suez road, Badr City, Cairo, Egypt)

1. Gipsovye materialy i izdelija (proizvodstvo i primenenie): Spravochnik / pod obshh. red. A.F. Ferronskoj [Gypsum materials and products (production and application: Handbook / under the Ed. by A.F. Ferron-skaya]. Moscow: ASV. 2004. 485 p.
2. Patent RU 2550630. Sposob prigotovleniya gipsotsementno-putstsolanovogo vyazhushchego [Method for preparing gypsum-cement-pozzolanic binder]. Izo-tov V.S., Mukhametrakhimov R.Kh., Galautdinov A.R. Declared 14.04.2014. Published 10.05.2015. Bulletin No. 13. (In Russian).
3. Petropavlovskaya V.B., Bardov N.P., Matveychuk V.V. Modification of the building gypsum properties. Science-intensive technologies and innovations: Collection of reports of the International scientific-practical conference dedicated to the 65th anniversary of BSTU named after V.G. Shukhov. Belgorod. 2019, pp. 325–329. (In Russian). DOI: 10.12737/conferencearticle_5cecedc3ad41d4.31814792
4. Kondratiena N., Sanytsky M., Soltysik R. Microstructure and properties of modified gypsum systems. Weimarer Gipstagung. Weimar. 2017, pp. 162–174.
5. Chernysheva N.V. The use of technogenic raw materials for increasing the water resistance of a composite gypsum binder. Stroitel’nye Materialy [Construction Materials]. 2014. No. 7, pp. 53–56. (In Russian).
6. Riechert C., Acshern W., Fischer H.-B. Puzzolanhaltige calciumsuifat –komposit-bindemittel für den einsatz in plattenförmigen produkten. Weimarer Gipstagung. Weimar. 2017, pp. 44–53.
7. Fernandez R., Martirena F., Scrivener K.L. The origin of the pozzolanic activing of calcined clay minerals: A comparsion between kaolinite, illite and montmorillonite. Cement and Concrete Research. 2011. Vol. 41, № 1, pp. 113–122. DOI: 10.1016/j.cemconres.2010.09.013
8. Izotov V.S., Mukhametrakhimov R.Kh., Galautdi-nov A.R. Investigation of the influence of active mineral additives on rheological, physical and mechanical properties of gypsum-cement-pozzolanic binder. Stroitel’nye Materialy [Construction Materials]. 2015. No. 5. pp. 20–23. (In Russian).
9. Yakovlev G.I. Polyanskikh I.S., Gordinа A.F. Properties of a gypsum binder modified with mechanically activated microsilica. Weimarer Gipstagung. Weimar. 2017, pp. 108–114.
10. Panchenko A.I., Kozlov N.V. Application of industrial waste to improve the water resistance of gypsum products. Weimarer Gipstagung. Weimar. 2017, pp. 345–352.
11. Khaliullin M.I., Faizrakhmanov I.I., Rakhimov R.Z. The influence of additives thermally activated clay on the properties of composite gypsum binder. Weimarer Gipstagung. Weimar 2017, pp. 328–332.
12. Pimenov A.I., Ibragimov R.A., Izotov V.S. Influence of ultrasonic treatment of the cement paste on the physical and mechanical properties of cement compositions. Stroitel’nye Materialy [Construction Materials]. 2015. No. 10, pp. 82–85. (In Russian).
13. Salakhov A.M., Morozov V.P., Salakhova R.A. Ultrasonic treatment as a method of mechanical activation of ceramic raw materials. Vestnik Kazanskogo tehnologicheskogo universiteta. 2013. Vol. 16. No. 21, pp. 88–91. (In Russian).
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15. Potapov V.V., Gorev D.S. Comparative results of increasing concrete strength by introducing nanosilica and microsilica. Sovremennye naukoemkie tehnologii. 2018. No. 9, pp. 98–102. (In Russian).
16. Batova M.D., Semenova Yu.A., Gordina A.F. Modification of binders based on calcium sulfates with finely dispersed mineral additives. Collection of materials of the XXIX Regional exhibition-session of student innovative projects and the Forum of scientific and technical creativity of youth of JSC “IEMZ” Kupol”. Izhevsk. 2020, pp. 58–61. (In Russian).

The ecological inferiority of the global linear economy based on uncontrolled consumption of natural resources, growing volumes of production and consumption waste, and the onset of the “Fourth Industrial Revolution” causes the transition to a new path of development. This path suggests a new world order based on the principles of a circular economy with a closed life-cycle, which is based on the waste-free production and consumption, and reuse of products. It is impossible to set up a closed production-use-recycling-production cycle within a single enterprise, even if it is large and multifunctional. Therefore, this problem should be solved within an economically developed region by creating a waste processing industry. Therefore, this region is turned into a waste-free industrial complex, where the principles of the circular economy are implemented. Only the building industry, which uses the widest variety of building materials and products, high levels of consumption of raw materials, and, most importantly, a long life-cycle of construction products, can become such a waste-processing industry. It is proposed to create the regional research and production associations called “Vtorstroyresurs”, which include scientific and technological centers and complexes of plants, producing construction materials and their components from waste products of the regional industry.

V.G. KHOZIN¹, Doctor of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.);
V.F. KHRITANKOV², Doctor of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
A.P. PICHUGIN², Doctor of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.)

¹ Kazan State University of Architecture and Engineering (1, Zelenaya Street, Kazan, 420043, Russian Federation)
² Novosibirsk State Agrarian University (160, Dobrolyubova Street, Novosibirsk, 630039, Russian Federation)

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2. Shalygina I.Yu., Nakhaev M.I., Kuznetsova I.N., Konovalov I.B., Zakharova P.V. Regional adapta-tion of the database of emissions of pollutants into the atmosphere. Gidrometeorologicheskiye issledova-niya i prognozy. 2018. No. 3 (369), pp. 33–45.(In Russian).
3. Chigina T.S., Iolin M.M., Borzova A.S., Chursina E.A., Sharova I.S. Analysis of emissions of pollutants into the atmosphere and the organization of their control. Geologiya, geografiya i global’naya energiya. 2017. No. 2 (65), pp. 120–130. (In Russian).
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