75504 2712-8172 Magazine of Civil Engineering 3 103 2021 1-168
RAR RUS 10301-10301 0000-0002-7774-1013 Peter the Great St. Petersburg Polytechnic University Gumeniuk Vasiliy gumenyuk.vi@yandex.ru 0000-0003-0301-0696 Saint-Petersburg University of State Fire Service of EMERCOM of Russia Kuzmin Anatoliy kaa47@mail.ru
St.Petersburg, Russia
 0000-0002-0220-0407 Saint-Petersburg University of State Fire Service of EMERCOM of Russia Romanov Nikolai nik57nik@mail.ru
St. Petersburg, Russia
 0000-0002-2081-6934 Saint-Petersburg University of State Fire Service of EMERCOM of Russia Permiakov Alexey jouker2005@yandex.ru
St. Petersburg, Russia
 Peter the Great St. Petersburg Polytechnic University Gumenyuk Oksana gumenyuk_ov@spbstu.ru
St. Petersburg, Russia
 57197818952 0000-0002-9822-3637 Graz University of Technology Dmitriev Ivan i.i.dmitriev@yandex.ru
Graz, Austria
 Porous inorganic materials for fire protection of industrial structures The necessity to study the thermophysical properties of porous inorganic materials is due to the wide use of thin-walled structures, the fire protective coating of which is performed when use porous materials. One of the most dangerous physical influence, leading to the destruction of thin-walled constructions in a fire, is a rapid increase in the temperatures of the combustion products in the fire zone. For a fire fencing, just 20÷30 minutes after its start, the temperature of the products in the combustion zone can reach 800÷900 °C, while the temperature can increase under more favorable conditions for the combustion process of air exchange. For open fires, when the air exchange conditions are not limited, the temperature of the combustion products can quickly reach 1100 °C of more. In the article, analyzing the effect on the porous materials of high-temperature combustion products, high humidity, direct exposure to water, as well as the process of phase of phase transitions of moisture contained in capillaries and its possible consequences. Presented and analyzing the influence of the process of thermal radiation inside gas-filled cellular structures on the heat-conducting properties of porous material based on perlite and expanded vermiculite. The results of an experiment to study the dependence of the thermal conductivity coefficient of expanded vermiculite on the specific particle size density and pressure suggest that with an increase in the temperature of the combustion products a thin-walled fire protection layer made of fibrous materials (for example, perlite and expanded vermiculite) with a decrease in the size of the solid fraction, the thermal conductivity coefficient of expanded vermiculite increases to a greater extent than of perlite, nab a certain tendency is observed to increase the share of the convective component in the thermal conductivity of expanded fire-protective materials as the particle sizes of their solid fraction decrease. 10.34910/MCE.103.1 fire fire protective materials thermo inductivity convections thermal radiation porous materials expanded vermiculite perlite https://engstroy.spbstu.ru/article/2021.103.1/
RAR RUS 10302-10302 Future expansion project of Tengizchevroil Zhakipbekov Shariphan science_2019@mail.ru
Atyrau, Republic of Kazakhstan
 8953635700 0000-0002-7700-0303 Eurasian National University named after L.N. Gumilyov Aruova Lyazat ecoeducation@mail.ru
St. Petersburg, Russia
 Karaganda State Technical University Toleubayeva Shamshygaiyn shamshygaiyn@mail.ru
Karaganda, Republic of Kazakhstan
 57140694600 0000-0002-6386-037X Karaganda State Technical University Ahmetganov Talgat ecology_2018@mail.ru
Karaganda, Republic of Kazakhstan
 57203584966 0000-0002-4173-206X Kyzylorda State University Utkelbaeva Aizhan ecoeducation@mail.ru
Kyzylorda, Republic of Kazakhstan
 The features of the hydration and structure formation process of modified low-clinker binders The effect of a complex additive consisting of silica fume and enrichment waste from the Karagailinsky mining and processing plant on the hydration and structure formation processes of cement systems is investigated. It was established that the introduction of a complex modifying additive consisting of silica fume and enrichment waste from the Karagailinsky mining and processing plant into the cement composition CEM I 42.5 N SR increases the compressive strength at the age of 28 days by 15.7–28 %. It was revealed that the studied complex additives contribute to an increase in the amount of chemically bound water. The processes of hydration and hardening of multicomponent modified binders were investigated. It is shown that the high strength of cement stone on a modified binder is due to the formation of stable low-base hydro silicates. The source of the formation of low-base calcium hydro silicates is the pozzolanic reaction, which proceeds with the binding of the clinker minerals released during hydration, portlandite silica complex additive. It is shown that purposefully changing the composition of the binder and hydration conditions, it is possible to improve the phase composition, morphology of hydrates and influence its final properties. 10.34910/MCE.103.2 modified binder hydration processes calcium hydro silicates binder composition complex modifying additive physical and chemical studies https://engstroy.spbstu.ru/article/2021.103.2/
RAR RUS 10303-10303 56450509500 0000-0002-4131-6138 Belgorod State Technological University named after V.G. Shukhov Frolov Nikolay frolov_pgs@mail.ru
Belgorod, Russia
 6507734920 0000-0003-2182-2049 Belgorod State Technological University named after V.G. Shukhov Smolyago Gennady tpk-psv@yandex.ru
Belgorod, Russia
 Reinforced concrete beams strength under power and environmental influences The article is devoted to the problem of assessing and predicting the strength of normal sections of bended reinforced concrete elements, which are exposed during operation to long-term force and environmental influences. It is noted that together with the accumulation of concrete and steel reinforcement corrosion damages, the load bearing capacity of reinforced concrete structures can be significantly reduced. At the same time, the existing methods for strength calculating are still applied and do not allow from a single point of view to reflect sufficiently strictly and in detail the stress-strain state of normal sections of bended reinforced concrete elements, taking into account the influence of all operational factors on it. Thereby, based on the nonlinear deformation model of reinforced concrete, a universal calculation procedure was developed. To approve it, the experimental studies of reinforced concrete beams samples that were under static load in sulfate- and chloride-containing aggressive environments for a long time were carried out. New features of corrosion damages accumulation in concrete and steel reinforcement in these aggressive environments were determined. After comparing the experimental and calculated data of normal sections strength, it was concluded that the proposed method has sufficient accuracy and can be used for practical calculations of operated bended reinforced concrete elements with defects and damages. 10.34910/MCE.103.3 durability reinforced concrete beams experimental investigations bending strength corrosion damages mechanical properties load https://engstroy.spbstu.ru/article/2021.103.3/
RAR RUS 10304-10304 0000-0001-5689-9906 Mizan-Tepi University Garedew Girmaye girmegare@gmail.com
Tepi, Ethiopia
 Cement and animal bone powder on rheological characteristics of bitumen The developed countries have adopted the use of modifiers for assessment of asphalt binder long term performance. Asphalt contributes 90 to 95 % in cost estimation of Flexible pavement while compared to all other major material components. Since Ethiopia is one of the landlocked country without any fossils fuel source for the production of Asphalt, moreover Ethiopian importer depends on neighbour country Djibouti. This research analyzes the effect of modifiers on the rheological characteristics and also considers fatigue resistance with the main aim of preventing rutting in asphalt pavement due to different temperatures. Hence a seminal effort is assessed in evaluation of Portland cement and Waste Animal Bone as cost effective modifying agents. The conventional bitumen penetration grade (80/100) is used in this research. The control specimen four binders were obtained by mixing the asphalt binder with four different percentages (0 %, 1 %, 3 % and 5 %) of PCWAB by weight of asphalt binder. Rheological characteristics were evaluated with Dynamic Shear Rheometer test (DSR) such as Amplitude sweep test (AST), Frequency sweep Test (FST) and Multiple-stress creep and recovery test (MSCR). AST and FST were adopted for determining linear visco-elastic range, Master curve were developed for same temperature (21.1 °C, 37.8 °C, and 54.4 °C) respectively while MSCR and Performance Grade (PG) were determined for four different temperatures (52 °C, 58 °C, 64 °C, and 70 °C). Finally, the master curve shows that 3% and more addition of PCWAB on asphalt binder increases the stiffening property of asphalt binder at high temperatures and low loading frequencies (susceptible for rutting). On the other hand, from the test result obtained from MSCR test the smallest total strain value was 5 % for PCWAB followed by the 3 % and 1 %. Thus, up to 3 % addition of PCWAB significantly improves the resistance of asphalt binder to rutting. In addition, using PCWAB as asphalt binder modifier has a positive impact on environmental preservation. The performance grade determination also depicted the improvement in PG as content of modifier increases. Therefore, the evaluation showed that the 3 % modified binder is better in its rutting performance with improved performance grade. 10.34910/MCE.103.4 asphalt binder animal bone cements rheological characteristics mechanical properties stiffness https://engstroy.spbstu.ru/article/2021.103.4/
RAR RUS 10305-10302 0000-0001-8079-2578 University of Civil Protection of the Ministry of Emergency Situations of the Republic of Belarus Marozau Artsiom
Minsk, Respublika Belarus
 University of Fire Safety of the Ministry of Public Security of the Socialist Republic of Vietnam Tran Duc Hoan websitet34@yahoo.com.vn
Hanoj, Vietnam
 0000-0002-9347-0778 University of Civil Protection of the Ministry of Emergency Situations of the Republic of Belarus Kamluk Andrei kan@ucp.by
Minsk, Respublika Belarus
 University of Civil Protection of the Ministry of Emergency Situations of the Republic of Belarus Parmon Valerij niipb@yahoo.ru
Minsk, Respublika Belarus
 University of Civil Protection of the Ministry of Emergency Situations of the Republic of Belarus Striganova Marina striganovam@tut.by
Minsk, Respublika Belarus
 Pump-hose systems with universal fire barrels for extinguishing buildings The hydraulic calculation of pump-hose system was carried out, taking into account the influence of its elements on the performance of fire barrels. Corresponding dependences for mixed pump-hose systems consisting of one and three fire barrels are presented. Based on the hydraulic calculation of the pump-hose system, it was found that an increase in the number of hoses to 12 in the main and up to 3 in the working line leads to a decrease in barrel consumption by 1.5 %, which does not affect fire fighting process. As a result of the analysis of the pump-hose system with three fire barrels when changing the main parameters in one of them, we can conclude that a significant effect on the flow rate is exerted by a change in the position of the dispenser, the height of the barrel and the number of hoses in the working line (total line resistance). It was also established that the flow rate of the other two system trunks varies slightly (1.5 %), which in practice can be ignored. Based on the data obtained, recommendations are given to the operator working on the pump of a fire truck when feeding fire extinguishing substances to a height. The presented research results are obtained in the field of fire extinguishing agents and methods of their application and can be used in fire fighting and emergency response. 10.34910/MCE.103.5 mechanical properties pressure buildings experimental investigations hydraulic calculation hydraulic resistance numerical methods https://engstroy.spbstu.ru/article/2021.103.5/
RAR RUS 10306-10306 57191530761 0000-0002-4765-5819 Moscow State University of Civil Engineering (National Research University) Alekseytsev Anatoly aalexw@mail.ru
Moscow, Russia
 Mechanical safety of reinforced concrete frames under complex emergency actions An approach to the calculation of the frame reinforced concrete structures taking into account the potential risk of financial losses in an emergency is proposed. The simplified conditions for the strength of structural components considering the potential relative risk of the financial losses for the structure during emergency failure of these components is formulated. The strain-stress state analysis using the finite element method based on bar models can be performed in dynamics. The reinforced concrete structural component in the form of a package of concrete and reinforcement layers that can be deformed according to actual diagrams approximated by piecewise linear functions. The calculations were considered by accounting geometric, structural and physical nonlinearity. As an example, illustrating the operability of the presented approach, were considered the frame of the building with several scenarios for emergency actions. This is a complete or partial exclusion of one column from the calculation model, accompanied by a horizontal impact. The exclusion of 0.75 and 0.5 parts of the cross section of the column as well as its complete exclusion, accompanied by a horizontal impact pulse were examined. A collision of a damaged structure with a rigid barrier and with a deformable base were simulated. The proposed approaches to modeling the stress-strain state and strength conditions of the bar reinforced concrete systems have prospects for using in algorithms of optimum parametric synthesis of structures based on metaheuristic approaches. 10.34910/MCE.103.6 reinforced concrete dynamic behaviour impact loading column removal progressive collapse risk safety frames nonlinear analysis https://engstroy.spbstu.ru/article/2021.103.6/
RAR RUS 10307-10307 6602722133 0000-0001-6895-4511 V.G. Shukhov Belgorod State Technological University Strokova Valeria vvstrokova@gmail.com
Belgorod, Russia
 6505921687 0000-0002-2761-0584 IMT Mines Alès Le Saout Gwenn gwenn.le-saout@mines-ales.fr
Alès, France
 56237522700 0000-0002-5736-5962 V.G. Shukhov Belgorod State Technological University Nelubova Victoria nelubova@list.ru
Belgorod, Russia
 56180889700 0000-0002-0199-7274 Belgorod State Technological University named after V.G. Shukhov Ogurtsova Yulia ogurtsova.y@yandex.ru
Belgorod, Russia
 Composition and properties of cement system with glutaraldehyde The experience of operating livestock farms shows that periodic reorganization does not prevent biological corrosion of building structures. In this work, the possibility of using glutaraldehyde as a fungicide for volumetric administration in the preparation of biostable concrete was investigated. The study aims to minimize the adverse effects of the components of commercial biocidal products on the physical and mechanical characteristics of products. For research, we used an aqueous solution of glutaraldehyde with an active substance concentration of 0.5 and 1 %, which was introduced into Portland cement CEM I 42.5 N as mixing water. The degree of influence of the active substance on the properties of cement paste and mortar was estimated according to data on heat release during hydration, strength, and phase composition. The fungicidal activity evaluation of glutaraldehyde in cement systems and the degree of their growth with the Aspergillus niger test culture were evaluated. It was established by isothermal calorimetry that, in mixtures with glutaraldehyde, a delay in the achievement of the main hydration peak is observed – by 30 minutes for 0.5 %, by 1 hour for 1 %. After 72 hours of hydration, a lower total amount of released heat of hydration is observed – for 0.5 and 1% solutions by 6.8 and 5.8 %, respectively. According to X-ray phase and differential thermal analyzes, the phase composition of the initial and aldehyde-modified cement stone on day 28 does not differ and consists of the following phases: ettringite, portlandite, calcite and clinker minerals. Varying the phase composition leads to a change in strength: when using a 0.5 % solution of aldehyde, the power of the cement-sand mortar increases by 6.5 %, and a 1 % solution decreases by 6.7 %. The use of a 0.5 % solution of glutaraldehyde provides a decrease in the intensity of fungal development and the formation of a fungistatic effect. Based on the results, a 0.5 % solution of glutaraldehyde can be recommended for the development of cement composites with prolonged bio-resistance. 10.34910/MCE.103.7 concrete construction biodegradation biocide cements hydration fungi chemical attack Aspergillus https://engstroy.spbstu.ru/article/2021.103.7/
RAR RUS 10308-10308 0000-0001-5912-1235 Don State Technical University Tiraturyan Artem tiraturjanartem@gmail.com
Rostov-on-Don, Russia
 57190176042 Don State Technical University Uglova Evgenia uglova.ev@yandex.ru
Rostov-on-Don, Russia
 0000-0002-7119-002X Don State Technical University Nikolenko Denis d.a.nikolenko@mail.ru
Rostov-on-Don, Russia
 0000-0002-3500-7187 Don State Technical University Nikolenko Maxim twinmax@mail.ru
Rostov-on-Don, Russia
 Model for determining the elastic moduli of road pavement layers A mathematical model of dynamic stress-strain state of a multilayer half-space, and a method for constructing and adjusting the design bowl of dynamic deflections under shock loading were developed to solve the problem of determining the elastic moduli of layers of non-rigid road pavement at the stage of its operation. Using this method, the actual dynamic elastic moduli of pavement layer materials were determined for a test section of road. In conclusion, the development prospects of the presented method are discussed as a result of analysis of amplitude-time characteristics of displacements recorded on road pavement surface under shock loading. 10.34910/MCE.103.8 asphalt pavements mechanical properties durability backcalculation numerical model deflection bowl https://engstroy.spbstu.ru/article/2021.103.8/
RAR RUS 10309-10309 57200793249 0000-0003-4851-1822 Beirut Arab University Jahami Ali ahjahamy@hotmail.com
Beirut, Lebanon
 0000-0001-8576-5544 Beirut Arab University Temsah Yehya ytemsah@bau.edu.lb
Beirut, Lebanon
 6701635056 0000-0002-4393-6728 University of Wolverhampton Khatib Jamal j.m.khatib@wlv.ac.uk
Wolverhampton, United Kingdom
 0000-0002-4854-0247 Beirut Arab University Baalbaki Ossama obaalbaki@bau.edu.lb
Beirut, Lebanon
 15080874300 0000-0003-3996-984X University of Blida Kenai Said sdkenai@yahoo.com
Blida, Algeria
 The behavior of CFRP strengthened RC beams subjected to blast loading Carbon Fiber Reinforced Polymer (CFRP) sheets have been widely used in strengthening different concrete elements such as beams, slabs, and columns. This sparked the interest of many researchers to conduct research on CFRP sheets; to have a better understanding for their behavior. This paper studied numerically the effect of using CFRP as a strengthening technique for Reinforced Concrete (RC) beams subjected to blast loading. A previous experimental investigation done by a Chinese researchers was considered in this study as a reference, and was modeled numerically (using ABAQUS) for this study. The model was then calibrated in order to conduct the numerical analysis on the effect of CFRP. Three different configurations of CFRP were considered: bottom CFRP strips for flexural strengthening, diagonal side strips for shear strengthening, and U-shaped strips for both shear and flexural strengthening. The variables considered in this study were; the mid-span deflection, strain in steel reinforcement and structural damage in both beams and CFRP sheets. Results showed that using CFRP in the bottom tensile face of RC beams helps in absorbing blast energy. In addition, using CFRP has shown a reduction in the tensile strain of the beam reinforcements. 10.34910/MCE.103.9 blast loading CFRP sheets deflection dynamic analysis impact damage strengthening https://engstroy.spbstu.ru/article/2021.103.9/
RAR RUS 10310-10310 0000-0002-0977-5086 Federal University of Rio Grande – FURG Pinto Vinicius viniciustorreseng@gmail.com
Rio Grande, Brazil
 0000-0003-1083-7341 Federal University of Rio Grande – FURG Cunha Marcelo marcelolamcunha@hotmail.com
Rio Grande, Brazil
 0000-0001-8441-0848 Federal University of Rio Grande – FURG Martins Kaue leaodoparque@gmail.com
Rio Grande, Brazil
 0000-0003-2409-3152 Federal University of Rio Grande – FURG Rocha Luiz luizor@unisinos.br
Rio Grande, Brazil
 0000-0003-4566-2350 Federal University of Rio Grande – FURG Dos Santos Elizaldo elizaldosantos@furg.br
Rio Grande, Brazil
 0000-0002-9337-3169 Federal University of Rio Grande – FURG Isoldi Liercio iercioisoldi@gmail.com
Rio Grande, Brazil
 Bending of stiffened plates considering different stiffeners orientations In engineering, the search for geometric configurations that lead to superior performance is always a design goal. Regarding structural components, such as plates, it is necessary to guarantee limits for its deflections, according to design standards. In this sense, methodologies devoted to reducing the out-of-plane displacements by geometric analysis are a relevant to subject research. Therefore, the present work is addressed to study several arrangements of stiffened steel plates defined by the Constructal Design Method (CDM). These plates were analyzed and solved applying computational modeling based on the Finite Element Method (FEM), aiming through the Exhaustive Search (ES) technique to evaluate the influence of stiffeners orientation on to the maximum deflection. Taking a non-stiffened plate as reference and keeping the total material volume constant, portions of its volume were transformed into stiffeners through the volumetric fraction parameter, representing the ratio between the volumes of stiffeners and reference plate. Adopting volumetric fraction values of 0.1; 0.2; 0.3; 0.4 and 0.5, it were established for each one 25 geometric arrangements of stiffened plates, considering the stiffeners orientations in 0 ° and 45 °, varying for each new arrangement the ratio between the height and thickness of the stiffeners hs/ts. The results showed that transforming a portion of material from a non-stiffened plate into stiffeners can decrease the maximum deflections by more than 95 %. Besides that, it has been demonstrated that stiffeners oriented at 45 ° can reduce maximum deflection by more than 60 % compared to stiffeners traditionally oriented at 0 °. 10.34910/MCE.103.10 stiffeners geometric optimization deflection numerical simulation computational modeling https://engstroy.spbstu.ru/article/2021.103.10/
RAR RUS 10311-10310 S-2766-2018 0000-0002-6111-201X National Research Moscow State Civil Engineering University Bazhenova Sofya sofia.bazhenova@gmail.com
Moscow, Russia
 National Research Moscow State Civil Engineering University Vu Kim Dien kimdienxdtb@gmail.com Modeling the influence of input factors on foam concrete properties The paper presents the use of blast furnace slag as a fine aggregate in foam concrete. Besides, the paper also presents the research results of the effect of the water-cement ratio and Silica fume on the mechanical properties of foam concrete. The absolute volume method was used to calculate the ratio of foam concrete mixture. Besides, the mechanical properties of foam concrete were determined at the age of 28 days. The method of Box-Wilson central composite design for two factors was used to predict the effect of the water-cement ratio and Silica fume on foam concrete properties. The results showed that the proposed regression equations of this mathematical model achieved an adequate prediction accuracy. Using computer programs obtained surface images of equations (10) and (12). Besides, the maximum value of the objective function was determined with compressive strength = 8.52 MPa and flexural strength = 1.21 MPa. This research result is a premise for studying foam concrete bricks to replace clay bricks in construction works. 10.34910/MCE.103.11 optimization concrete mixtures mechanical properties cement brick silica fume https://engstroy.spbstu.ru/article/2021.103.11/
RAR RUS 10312-10312 0000-0003-2533-9732 National Research Moscow State Civil Engineering University Samarin Oleg samarin-oleg@mail.ru Thermal mode of a room with integrated regulation of cooling systems An air-conditioned room with automatic regulation of the climate systems serving it using complex control algorithms is one of the most difficult objects for calculating non-stationary thermal regime, so to date, this method is insufficiently studied. At the same time, such objects are typical when organizing the internal microclimate of civil buildings. In this paper, we consider the mathematical formulation and solution of the problem of changing the temperature of internal air in a room equipped with automated local cooling systems and a background supply ventilation system under variable thermal influences. The main equations connecting the most important components of the heat flow in the room are analyzed. The dependence on time for the deviation of the room air temperature from the setpoint is presented, and the expression for the moment of time at which the maximum temperature deviation is observed, with a jump-like change in the heat flow from heat sources in the case of regulating the equipment of local cooling systems according to the integral law. Calculations were performed to confirm the analytical solution obtained using a finite-difference approximation of the differential equations of heat balance and heat transfer on the example of one of the currently existing residential buildings in the climatic conditions of Moscow, taking into account the structural characteristics of the building and the thermal properties of its enclosing structures. It is noted that the greatest deviation of the temperature from the setpoint (dynamic control error) in the first approximation is inversely proportional to the cubic root of the transmission coefficient of the regulator, as well as the moment of time for which this deviation is observed. The obtained relations are proposed to be used for an analytical assessment of the non-stationary thermal regime of an air-conditioned room served by local cooling systems equipped with an automation system with an integral law of regulation, to check the conditions of human comfort and safety, as well as to determine the required parameters of the regulator. 10.34910/MCE.103.12 microclimate temperature heat balance heat gain regulation integral algorithm transmission coefficient civil engineering building construction industry https://engstroy.spbstu.ru/article/2021.103.12/
RAR RUS 10313-10313 26031561100 0000-0003-0085-9934 Eurasian National University of L.N.Gumilyov Lukpanov Rauan Rauan_82@mail.ru
Nur-Sultan, Kazakhstan
 0000-0001-6118-5238 Eurasian National University named after L.N. Gumilyov Dyussembinov Duman dusembinov@mail.ru
Nur-Sultan, Kazakhstan
 55848149600 0000-0001-6723-175X L.N. Gumilyov Eurasian National University Utepov Yelbek utepov-elbek@mail.ru
Nur-Sultan, Kazakhstan
 55339733600 0000-0001-8547-5440 Eurasian National University named after L.N. Gumilyov Bazarbayev Daniyar phdd84@mail.ru
Nur-Sultan, Kazakhstan
 57204727444 0000-0002-7061-699X Eurasian National University named after L.N. Gumilyov Tsygulyov Denis denis_riza_72@mail.ru
Nur-Sultan, Kazakhstan
 57193734744 0000-0002-5984-9346 Eurasian National University named after L.N. Gumilyov Yenkebayev Serik yenkebayev-serik@mail.ru
Nur-Sultan, Kazakhstan
 55378440800 0000-0003-1680-5287 Eurasian National University named after L.N. Gumilyov Shakhmov Zhanbolat zhanbolat8624@mail.ru
Nur-Sultan, Kazakhstan
 Homogeneous pore distribution in foam concrete by two-stage foaming The article addresses the issues of investigating the homogeneity of foam concrete produced by three methods: the classical method (CM), dry foam mineralization (DM), as well as the proposed method of two-stage foaming (TSF). The study is necessary due to the impact of the manufacturing process on the homogeneity degree of foam concrete. Therefore, the TSF method is aimed at improving the homogeneity of the material structure by evenly distributing the pores through the sequential foam introduction. The homogeneity of the materials produced by the three methods was evaluated by comparing the results of discrete (point and localized) strength testing over the entire volume of the foam concrete blocks, as well as the results of thermal conductivity measurements. The test results obtained gave an understanding of the degree of materials homogeneity, and confirmed the impact of the foam concrete manufacturing process on its quality. Thus, the most homogeneous material structure throughout the entire volume is observed in TSF specimens, as evidenced by the minimum deviations of particular values of strength and thermal conductivity, ranging from 4.19 % (in the analysis of thermal conductivity) to 6.71 % (in the analysis of strength), while the same indicators for CM specimens are 22.4 % and 48.35 %, and for DM specimens are 11.05 % and 19.21 %, respectively. 10.34910/MCE.103.13 concretes pore size foam mortar strength mixtures https://engstroy.spbstu.ru/article/2021.103.13/
RAR RUS 10314-10314 56434340300 0000-0002-5694-1737 Peter the Great St. Petersburg Polytechnic University Usanova Kseniia plml@mail.ru
St. Petersburg, Russia
 7801686579 0000-0001-7011-8213 Peter the Great Saint Petersburg Polytechnic University Barabanschikov Yuri ugb@mail.ru
Polytechnicheskay, 29
 0000-0002-4393-8205 Peter the Great St. Petersburg Polytechnic University Krasova Anastasiya krasova-nastya14@mail.ru
St. Petersburg, Russia
 0000-0002-2908-4565 Peter the Great St. Petersburg Polytechnic University Akimov Stanislav akimov_sv@spbstu.ru
St. Petersburg, Russia
 Peter the Great Saint Petersburg Polytechnic University Belyaeva Svetlana sbelaeva@gmail.com
Polytechnicheskay, 29
 Plastic shrinkage of concrete modified by metakaolin The subject of research is concrete containing a polycarboxylate superplasticizer admixture and metakaolin. The effect of water-cement ratio, superplasticizer, and metakaolin on plastic shrinkage of cement paste was investigated. Two types of cement are also compared. One of them was alite-aluminate cement (cement A). Another one was belite-celite cement (cement B). If the water-cement ratio is increased, then the plastic shrinkage of samples with both cements develops more intensively and achieves higher values. However, the w/c ratio affects the shrinkage of the cement A more. For the first 8 hours, the cement A shrinkage is 1.71–5.21 mm/m at W/C = 0.2–0.35. For cement B, the corresponding values are 0.953–2.63 mm/m. The cement A's plastic shrinkage is 1.51–1.98 times higher than cement B's plastic shrinkage. If polycarboxylate superplasticizer content is increased, then the shrinkage of both cements increases significantly due to the release of part of physically bound water and its evaporation. The addition of the superplasticizer increases the shrinkage of the cement A by an average of 40 %, and the shrinkage of cement B by approximately twice. Simultaneously, the shrinkage of two cements becomes approximately equal due to the same rate of interaction of water with the cement, limited by the diffusion of water through the polycarboxylate adsorption film. Selective capacity of polycarboxylate concerning two types of cement is shown. The alite-aluminate cement gives the same shrinkage as the belite-celite cement, with a 1.89 times higher superplasticizer content. Replacing part of the cement by metakaolin reduces the initial shrinkage, however, not so significantly as the other two factors. If the metakaolin content in the binder is increased, then the shrinkage of both cements decreases. More noticeable is the effect of metakaolin on the cement A. The shrinkage of the cement B has not changed much. 10.34910/MCE.103.14 cement concrete heat release heat of hydration plastic shrinkage early age shrinkage autogenous shrinkage superplasticizer metakaolin concrete mixtures concrete additives cracks https://engstroy.spbstu.ru/article/2021.103.14/