Experimental Studies of Heat Resistance and Compressive Strength of Heat-Resistant Concrete

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Here, instead of large and small aggregates, the effect of the use of secondary refractory substances in reducing the cost of the concrete mixture is studied. The value of the study is to prove that heat-resistant concrete meets the technological requirements of a liquid-layer furnace, as well as experimental confirmation of the possibility of using secondary refractory materials as heat-resistant concrete aggregates. To solve this problem, it was proposed to replace the traditional method of facing the boiling floor furnaces (Fireclay brick of the SHB brand) with a monolithic concrete version. Considering that the technological feature of the boiling layer of the furnace is a high temperature up to 1000°C and an aggressive environment that causes SO 3 gaseous sulfur, one of the well-known types of heat-resistant concretes, the sodium-infused liquid glass concrete type is selected as the base, and instead of cement, it is recommended to use liquid glass with low thermal conductivity, such as a material in the amorphous phase and a glass-layered composite viscous substance. fluidized bed furnace heat-resistance concrete fire-resistance concrete lining secondary refractories Figures Figure 1 Figure 2 Figure 3 1. Introduction The increasing construction of various thermal units, as well as load-bearing structures operating in conditions of simultaneous exposure to high (constant and variable) temperatures and various aggressive environments, requires an increase in the production of heat-resistant and chemically resistant materials, the creation of new heat-resistant materials and the development of such building structures that would increase the service life of thermal units and apply industrial methods construction [ 1 ]. Fluidized bed furnaces (hereinafter referred to as fluidized bed furnaces) are one of the units that operate under conditions of simultaneous exposure to constant high temperature and aggressive environment. Currently, fluidized bed furnaces are lined with fireclay refractories, [ 2 ]. The working chamber lining consists of a working layer made of fireclay refractory and a thermal insulation layer made of sheet asbestos. In the lower part of the chamber, the lining thickness is 3 bricks, in the upper part – 0.5 bricks. To maintain the gas temperature sufficient to complete the particle oxidation process, the thermal insulation layer of the working chamber above the fluidized bed is additionally lined with lightweight fireclay or diatomaceous earth refractories (40–70 mm thick with asbestos), [ 3 ]. The furnace bottom is made of heat-resistant concrete on liquid glass or Portland cement and is a plate or arch with a thickness of 200–300 mm with holes for gas distribution nozzles. The furnace roof, the arched loading chamber, and the discharge chamber adjacent to the furnace wall are also lined with fireclay refractory [4[. One of the problems that arise during operation is the lack of compliance with the quality of work performed when lining fluidized bed furnaces. Currently, the shaft walls and the furnace dome are lined with category I fire-resistant masonry, and the furnace bottom is filled with heat-resistant concrete [ 5 ]. In the process of operation of the furnace was identified deficiencies in the lining piece materials such as [ 4 ]: the structure of mastic density less than the density of the brick – it leads to blowing mastic from the masonry joints; incorrect sequence of works is manifested in the fact that, you first need to fill the bottom of the furnace, and then is made masonry walls of the furnace stack, now do the opposite, resulting in the lining of the hearth furnace technology of the seam, in the process of operation of the furnace, at high temperatures, concrete can shrink, which leads to the formation of crack – this in turn leads to the melting of the steel sheet of the base of the furnace, also, the defect violates the technological process of firing, due to the fact that the steel sheet hearth furnace took a bowl, there are additional areas between the liner and the steel furnace body, where it goes part of the air supplied to create a fluidized bed is a violation of the forced to serve a greater amount of air [ 6 ]; the absence or the insufficient size of the expansion joint between the liner and the steel furnace body, now as an expansion joint acts 1 sheet 5 mm thick asbestos cardboard that are glued to a steel furnace body, this event is not effective due to the low thickness of the expansion joint is that in winter, resulting in deformation, and in some cases the rupture of the steel casing of the furnace [ 7 ]. All these disadvantages lead to disruption of the technological process of zinc production, which leads to a decrease in the concentration of SO 2 in the exhaust gases, leads to an increase in the amount of oxygen required for the oxidation reaction of zinc concentrates during the firing process and, as a result, a decrease in the quality of the resulting cathode zinc [ 8 ]. Currently, one of the dominant issues facing non-ferrous metallurgy enterprises is to increase the productivity of fluidized bed roasting furnaces by increasing the lifetime of the furnace [ 9 ]. Therefore, to solve this issue, it is proposed to replace the traditional method of lining fluidized bed furnaces with piece materials fluidized bed with a monolithic concrete version, but for this it is necessary to prove that heat-resistant concrete meets the technological requirements of these furnaces [ 10 ]. The technological feature of fluidized bed furnaces is that the lining is simultaneously affected by high temperatures up to 1000°C and an aggressive environment caused by sulfur dioxide SO 3 . Of the known types of heat-resistant concretes, liquid glass concrete with the addition of sodium silicofluoride is both heat-resistant and chemical-resistant [ 11 ]. It was this type of concrete that was chosen as the basis. The relevance of the chosen topic is to increase the productivity of fluidized bed furnaces by reducing downtime during repairs. 2. Main Part of Research 2.1 Materials and Methods Heat-resistant concrete is currently being used for the manufacture of prefabricated elements, as well as monolithic structures. Examples of its rational use in industry can be multi-pod furnaces for burning sulfur pyrite, coarse dust collectors and dust chambers, covers of the ABM-1.5A unit, lining of profitable superstructures, furnaces with a boiling (fluidized) layer, lining of trolleys of tunnel furnaces [ 12 ]. The developed design of the monolithic lining of the fluidized bed furnace is a cylindrical steel furnace body, glued with several layers of asbestos cardboard. Next comes a layer of monolithic heat-resistant concrete on liquid glass with structural reinforcement with grids in the walls and a spatial frame in a domed vault [ 13 ]. The hearth is filled with heat-resistant concrete, the role of reinforcement is performed by steel nozzles of the hearth [ 14 ]. The new design of the monolithic lining of fluidized bed furnaces was developed taking into account the requirements of regulatory documents of the Republic of Kazakhstan, and the requirements of foreign documents. Thus, the value of the concrete protective layer for reinforcement was determined in accordance with the requirements [ 5 , 15 ], and the results of scientific tests [ 16 , 17 ]. A team of authors Bolshakov D. V., Bolshakov V. V., Nemtsev V. S., Goltsev A. G. obtained an innovative patent of the Republic of Kazakhstan for the developed design of a monolithic furnace lining under the number 28370. A special feature of the composition of heat-resistant concrete is that in order to reduce the cost of the concrete mix, a broken brick of the SHCU brand from the fireclay zone of the refractory lining of the Welz furnace is used as a coarse and fine aggregate [ 18 ]. Bricks of the SHCU brand were crushed to a certain fraction in accordance with the interstate standard − 20910 − 2019. The main task of selecting the composition of heat-resistant concrete on liquid glass, is to choose such a ratio between fine and coarse aggregate, in which the binder consumption would be minimal in order to ensure minimal porosity and shrinkage of concrete, as well as high refractory properties of concrete [ 19 ]. The true total porosity of concrete on liquid glass depends on the true porosity of the aggregate, which is reduced to some extent due to impregnation with liquid glass, on the true porosity of the hardened binder and on the voids that have appeared in the concrete between the aggregate grains. Porosity is one of the most important characteristics of materials operating at high temperatures. As the porosity decreases, the strength of the material increases and its resistance to high temperatures and aggressive environments increases [ 20 ]. In addition to porosity, one of the main characteristics of heat-resistant concrete is temperature shrinkage, which mainly depends on the composition and amount of binder. The more binder is added to the concrete, the greater the shrinkage of the concrete. In this regard, to reduce shrinkage, it is necessary to reduce the consumption of binder in concrete. In most cases, the reduction in consumption is also due to its lower refractoriness compared to aggregates. Selection of the composition of heat-resistant concrete производиwas made using the method proposed by F. I. Melnikov as a basis. The basic principle of calculating the composition of heat-resistant concrete on liquid glass is to ensure that the voids between the aggregate grains are filled with a binder dough in such a way that the necessary workability of the concrete mixture is obtained. The volume of the binder dough must be introduced into the concrete mix with some excess in comparison with the volume of intergranular space. This excess should correspond, first, to the volume that is necessary to ensure the workability of the concrete mix, and, secondly, to the volume that is absorbed into the pores when using a porous aggregate [ 21 , 22 ]. 2.2 Mathematical Justification of the Research To obtain aggregate mixtures with minimal voidness, dry mixtures of coarse and fine chamotte aggregate were prepared in different weight ratios. For each mixture, the bulk density was determined when compacting it on a vibrating platform. It was found that the highest bulk density of 1700 kg /m 3 corresponds to the ratio of fine and coarse fractions 65: 35 (%by weight), i.e. with a higher proportion of fine aggregate. However, experimental studies have shown that with a large flow rate of fine aggregate, the need for liquid glass increases significantly due to the large specific surface area of the aggregate [ 23 ]. Taking into account the consumption of liquid glass, it was found that the optimal ratio of fine and coarse aggregates is 40: 60. The average density of the mixture in this case is 1620 kg/m 3 . All calculations were performed according to the main methods set out in regulatory documents [ 24 , 25 ]. The consumption of aggregates (coarse and fine) per 1m 3 of concrete mix is determined by Eqs. ( 1 ) $${P}_{a}=\frac{1000}{\frac{1}{{\rho }_{a.d}}+\frac{\alpha \cdot {К}_{exc}}{{\rho }_{a}}}$$ 1 where: ρ a aggregate consumption kg, ρ a.d apparent aggregate density t/m 3 , α voidness of the aggregate. K exc excess coefficient of the binder dough (taking into account the workability of the concrete mix, the excess coefficient can be assumed to be equal to 1.5. ρ a average density of a mixture of fine and coarse aggregates t/m 3 (not in the compacted state). The consumption of coarse aggregate K is determined based on the established optimal ratio of aggregates by Eqs. ( 2 ): $$K={P}_{a}\cdot k$$ 2 where k is the percentage of a large placeholder. The consumption of fine aggregate M is determined by Eqs. ( 3 ) $$M=\left({P}_{a}-K\right)\cdot \left(1+\text{g}\right)$$ 3 where g is the fraction of particles with a size of at least 0.14 mm in the fine aggregate. The voidness of the aggregate α a is determined experimentally or by the Eqs. ( 4 ) $${\alpha }_{a}=\frac{{\rho }_{a.d}-{\rho }_{a}}{{\rho }_{a.d}}$$ 4 where ρ a.d apparent density (or average density in a piece) of aggregate, t/m 3 ρ a bulk density of aggregate t/m 3 . The consumption of a mixture of hardener and fine-ground additives for concrete on liquid glass is calculated by Eqs. ( 5 ) $$N=\frac{{\alpha }_{a}\bullet {P}_{a}\bullet {\rho }_{\text{f}}\bullet {K}_{exc}}{{\rho }_{a}}$$ 5 where N is the mass of the mixture of finely ground additive and hardener kg, Р a total mass of small and large aggregates kg, ρ f bulk density of the fine-ground additive t/m 3 , K exc coefficient of excess of astringent dough, ρ a is the bulk density of a mixture of fine and coarse aggregates t/m 3 . The excess coefficient of astringent dough was determined experimentally. To do this, based on the calculation, test mixes were prepared with different coefficients of excess binder in the range of 1.2–1.8, while the workability of the concrete mixture was also determined. As a result of the conducted studies, it was found that sufficient workability of concrete mixes was obtained with an excess coefficient of binder dough equal to 1.5. The flow rate of liquid glass should be determined by the Eqs. ( 6 ) $${Р}_{l}=\left(\frac{N}{{\rho }_{f}}+\frac{{Р}_{l}\cdot W}{{\rho }_{l}\cdot 100}\right)\cdot {\rho }_{l.\text{g}}$$ 6 where Р l mass of liquid glass kg, W water absorption of aggregates %, p l.g density of liquid glass t/m 3 , p f is the density of the fine-ground additive t/m 3 . To determine water absorption, take an average sample of 0.5 kg of aggregate fraction 2.5 mm, dried to a constant mass, placed in a vessel and filled with water at room temperature. After 2 hours of soaking, the water is drained through a sieve with holes of no more than 1.25 mm. The aggregate is lightly wiped with a pre-moistened and wrung out towel and weighed. Partial water absorption,%, is calculated by Eqs. ( 7 ) $$W=\frac{{Р}_{w}-Р}{Р}\cdot 100$$ 7 where P w mass of the aggregate saturated with water kg, P mass of dry aggregate kg. The hardener consumption is determined by Eqs. ( 8 ) $$O=m\cdot {P}_{l}$$ 8 where O is the mass of the hardener kg, m is the proportion of the hardener. The consumption of hardener is determined experimentally in the development of binder and concrete compositions, and it depends on the type of fine-ground additive. When using chamotte, its share is 0.1–0.15 of the mass of liquid glass. The consumption of fine-ground additives is calculated by Eqs. ( 9 ) $$T=N\cdot O$$ 9 where T is the weight of the fine-ground additive kg, N mass of the mixture of finely ground additive and hardener kg, O mass of the hardener kg. Further, the calculation of heat-resistant concrete on liquid glass was performed by Logunin and Sokov (2018), in the presence of the following materials: liquid glass with a density of 1.38, fireclay aggregate with a particle content of less than 0.14 mm in fine aggregate of 10%, water absorption of aggregate of 9%, fine-ground additive (mortar). The consumption of fine and coarse aggregates is determined from formula Eqs. ( 1 ): \({P}_{з}=\frac{1000}{\frac{1}{2}+\frac{\text{0,3}\cdot \text{1,5}}{\text{1,35}}}=1200\) kg; Mass of coarse aggregate according to Eqs. ( 2 ) \(K=1200\cdot \text{0,6}=720\) kg; Mass of fine aggregate according to Eqs. ( 3 ) \(М=\left(1200-720\right)\cdot \left(1+\frac{10}{100}\right)\approx 530\) kg; The voidness of the aggregate is determined by the Eqs. ( 4 ) $${\alpha }_{з}=\frac{2-\text{1,35}}{2}\approx \text{0,32}$$ ; The consumption of fine-ground additive and hardener is found by the Eqs. ( 5 ) \(N=\frac{\text{0,32}\cdot 1200\cdot \text{1,2}\cdot \text{1,5}}{\text{1,35}}=511\) kg; The flow rate of liquid glass is calculated from Eqs. ( 6 ) \({Р}_{l}=\left(\frac{511}{\text{2,65}}+\frac{1200\cdot \text{0,09}}{\text{1,35}}\right)\cdot \text{1,38}=385\) kg; The consumption of sodium silicofluoride per 1m 3 of heat-resistant concrete according to formula (8) is 10–15% of the mass of liquid glass, then \(O=\text{0,12}\cdot 385=46\) kg; The consumption of the fine-ground additive according to Eqs. ( 9 ) is \(T=511-46=465\) kg. The consumption of materials per 1m 3 of heat-resistant concrete on liquid glass with fireclay aggregate using welz-furnace lining breakage is shown in Table 1 . Table 1 Material consumption, kg per 1m 3 of heat-resistant concrete Name Consumption, kg Liquid glass 385 Sodium silicofluoride 46 Mortar 465 Chamotte filler: small 530 large 720 Figure 1 shows a broken welz furnace lining, a brick SHCU and a large aggregate made from it. 3. Methods of Conducting Experimental Research To assess the quality of the fluidized bed furnace lining with heat-resistant monolithic concrete using secondary refractories, it is necessary to check experimentally, highlighting the main characteristics from a number of physical and mechanical properties of heat-resistant concrete. The fluidized bed furnace lining consists of a shaft with a height of 13 m, a diameter of 7.6 m and a dome arch with a lifting boom of 1.15 m. Therefore, to calculate the lining structure for load-bearing capacity, it is necessary to determine the compressive strength of concrete. In order to find out whether concrete can withstand the gradual heating and cooling associated with stopping the furnace for current and major repairs, it is necessary to determine its thermal resistance. To obtain a composition with a degree of reliability of P = 0.9, for strength testing, in accordance with The interstate standard 20910 − 2019, it is necessary to produce at least 3 cubes with a rib height of 100 mm, for heat resistance testing, in accordance with the interstate standard 20910 − 2019, it is necessary to produce at least 3 cubes with a rib height of 70 mm. Existing methods of testing for thermal stability are very imperfect, as they do not reflect the actual operating conditions of fluidized bed furnaces and other thermal units. Each heating unit has its own time period for heating and cooling, and cannot be equated with another unit. Also, not all types of heat-resistant concrete are resistant to cooling in an aqueous environment; for heat-resistant concrete on liquid glass, air cooling is necessary [ 20 , 26 ]. The standard method for determining the thermal resistance of refractory materials for testing heat-resistant concrete on liquid glass is not applicable, since the destruction of concrete during testing can occur not only as a result of a sharp change in temperature, but also from the action of water on concrete. To determine the thermal resistance of heat-resistant concrete, a method was adopted in accordance with the interstate standard 20910 − 2019 in the Appendix 5 "Method for determining the heat resistance of concrete”, in which samples-cubes with a size of 70×70×70 mm are placed in a preheated oven to 800°C and kept at this temperature for 40 min. Then the samples are removed from the furnace and cooled in an air stream (air cooling) to a temperature of 30–50°C. After each heat change, the remaining cubes are examined and then the appearance of cracks, the nature of destruction and weight loss are noted. Then the cubes are placed back in the oven, kept at 800°C for 40 min , and cooled in the above order. Heating and subsequent cooling of the cubes is carried out until the samples lose 20% of their original weight or until they are completely destroyed. For testing, two series of samples “1 from 12.07” and “4 from 16.07” were made from a given concrete composition. The series "1 from 12.07" consists of six cubes, the series "4 from 16.07" consists of three cubes. All cubes with an edge height of 70 and a mass from 630 to 710 g. The test progress is described below: - when heated to 800°C, all cubes lost approximately 20 g in mass; - when heated to 900°C, the cubes marked " 4 from 16.07” began to stick to the fireclay brick on which they were standing. After cooling, dark streaks and shallow depressions appeared, there were no noticeable mass losses (cubes “4 from 16.07 " were no longer tested). Cubes marked " 1 from 12.07” withstood 12 heat changes without significant changes and weight losses; - when heated to 1000°C on the cubes marked “1 from 12.07”, dark streaks and small depressions appeared, there were no noticeable losses in mass. - when heated to 1200°C, the cubes marked "1 from 12.07" melted, darkened and melted to the fireclay brick on which they stood. 4. Results and Discussions According to the test results of two series of samples “1 from 12.07” and “4 from 16.07", it is safe to say that the series “1 from 12.07” with the predominant number of cubes from two series, withstood 12 heat changes at a temperature of 900°C, which proves that it fully meets the requirements of heat-resistant concrete for heat resistance according to SN 156 − 67. A series of cubes "4 from 16.07" withstood a smaller number of heat changes at a temperature of 900°C, but at a temperature of 800°C, this series of samples showed good resistance indicators. The reason for the small number of heat changes in the series of samples “4 from 16.07” was the unsatisfactory quality of liquid glass in the composition of heat-resistant concrete. In the production of two series of cubes, liquid glass of different batches of cooking was used. The results of tests for determining heat resistance are shown in Table 2 , photos are shown in Fig. 2 (a), (b) and (c). Table 2 Thermal stability of heat-resistant concrete № p/p Dimensions of samples, mm Weight of samples, g Volume weight of samples at the time of testing, kgs/m 3 Age, day Number of heat changes of the sample, R ts air, 900°C Average number of heat changes in a series of samples, R ts Heat-resistant concrete №1 1 70 610 1780 90 12 12,5 2 70 640 1870 12 3 70 640 1870 12 4 70 650 1900 94 12 5 70 660 1920 14 6 70 670 1950 13 Heat-resistant concrete №4 4 70 640 1870 93 2 1,3 5 70 690 2010 1 6 70 690 2010 1 To determine the compressive strength of concrete from a given concrete composition, two series of samples “2 from 13.07” and “3 from 13.07” were made, three cubes in each series with a rib height of 100 mm. The strength test was performed on a MS-500 press. Before starting the tests, the manufactured cubes were weighed and the actual dimensions of the sides were measured. After that, the cubes were placed under a press, where they were crushed to complete destruction [ 4 , 13 ]. The calculated value of the brand strength was determined by Eqs. ( 10 ). $${R}_{b\left(n\right)}={R}_{b\left(28\right)}\cdot \frac{{ln}28}{{ln}n}$$ 10 where R b(n) and R b(28) are the ultimate strength of concrete after n and 28 days, kgs /cm 2 , ln n and ln 28 are decimal logarithms of the concrete age. The test results for determining compressive strength are shown in Table 3 , photos are shown in Fig. 3. Table 3 Compressive strength of heat-resistant concrete № p/p Dimensions of samples, mm Weight of samples, g Volume weight of samples at the time of testing, kgs/m 3 Age, day. Strength of samples during testing, kgs / cm 2 Strength of concrete during testing, kgs/cm 2 Calculated value of brand strength, kgs / cm 2 Heat-resistant concrete №2 1 100×99×103 1960 1922 83 250,47 270,45 203,94 2 102×100×101 1990 1932 273,40 3 105×100×101 1995 1881 267.49 Heat-resistant concrete №3 4 104×101×102 1990 1858 83 262,90 269,53 203,25 5 102×101×101 1980 1903 266,98 6 105×100×103 2025 1872 272,08 (a) two series of samples “2 from 13.07” (b) testing of samples on the MS-500 press and " 3 from 13.07” Figure 3 Photos of cube strength tests 5. Conclusions The conducted experiment proved the possibility of using secondary refractory products as aggregates for heat-resistant concrete. This will allow using secondary refractories to reduce the cost of the concrete mix. Changing the composition of concrete can improve its heat resistance and strength. It has been found that the addition of various additives, such as mixtures of second-use refractories, can increase the ability of concrete to withstand high temperatures without losing strength. Experiments have shown that heat-resistant concrete can retain a significant part of its strength at high temperatures. However, when a certain temperature is reached, the material begins to lose strength due to changes. Under these conditions, the solution to the problem is to use liquid glass for a boiling furnace as a filling material, presented by the research experience. Experimental data allow us to evaluate the behavior of concrete at different temperatures and give recommendations for its use in different conditions. The research results contribute to the creation of standards for heat-resistant concrete that help engineers and builders choose materials according to specific projects, taking into account the operating conditions, and are the optimal solution. The possibility of using heat-resistant concrete on liquid glass for lining fluidized bed furnaces has been proven, which is characterized by a number of advantages over lining the furnace with piece materials: - reduction in the number or complete absence of masonry seams; - increases the service life of the furnace due to the durability of the lining – this is due to the fact that мthe monolithic lining has high strength characteristics and resistance in aggressive environments; - reduces the repair time of the unit due to the high adhesive properties of heat-resistant concrete on liquid glass; - faster commissioning of the unit due to rapid strength gain and accelerated drying modes. These results are important for developing more efficient building materials that can withstand extreme conditions and ensure the safety and durability of structures in a variety of environments. 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Journal of University of Science and Technology Beijing - J UNIV SCI TECHNOL BEIJING. 13. 497-503. DOI:10.1016/S1005-8850(06)60101-1 Zhao, Hong-bo & Huo, Shou-feng & Cheng, Shu-sen. (2013) Study on the early warning mechanism for the security of blast furnace hearths. International Journal of Minerals, Metallurgy, and Materials. 20. DOI: 10.1007/s12613-013-0733-4 Zuginisov, M.T. & Myrzahmetov, M.M. & Sartayev, D.T. & Orynbekov, E.S.. (2014) Heat-resistant ferrochrome slag based concrete. Magazine of Civil Engineering. 51. 38-45. DOI:10.5862/MCE.51.5 Logunin, Alexey & Sokov, Victor. (2018) Effective polystyrene concrete using glass cullet and liquid glass. IOP Conference Series: Materials Science and Engineering. 365. 032045. 10.1088/1757-899X/365/3/032045. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4005194","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Method Article","associatedPublications":[],"authors":[{"id":275943965,"identity":"1c96fc14-5d7c-468f-86f9-68a5252f5012","order_by":0,"name":"Baitak Apshikur","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6ElEQVRIie3RMQrCMBSA4ScFuzxwTSneISVQEUWvklLIVMXRUXBw8QARvIdrJKvSVXASV3EpiIOg0YIgSujokB+SofCRlxTA5frDqFkeUA7gT4C8P1QjqEqC1QgYQnhF0vK3uhiNRLJaHNd7hC7rE+5FVwtpz4cilDRLlnuRdhBEjIZwYhtMZbGHdJzIMItDBN19EkVtJD+x4kWC/GLIvSTcRnYZDdEMJgnWDVHlYMp2F3kWhggmUbD2kqYMN4dpNLGQVmOgC7ylTenrw+407kWzWaoD24uZX/gx53Or2c74Ii6Xy+X60QOOPUM0W/k5CwAAAABJRU5ErkJggg==","orcid":"","institution":"Ust-Kamenogorsk","correspondingAuthor":true,"prefix":"","firstName":"Baitak","middleName":"","lastName":"Apshikur","suffix":""},{"id":275943966,"identity":"6509510b-b250-4f47-a45c-0ea875fb8e1a","order_by":1,"name":"Anatoly Grigoryevich Goltsev","email":"","orcid":"","institution":"Ust-Kamenogorsk","correspondingAuthor":false,"prefix":"","firstName":"Anatoly","middleName":"Grigoryevich","lastName":"Goltsev","suffix":""},{"id":275943967,"identity":"61fd5dd9-27e5-4485-81f8-f6787ab6ab34","order_by":2,"name":"Murat Mametkulovich Alimkulov","email":"","orcid":"","institution":"Ust-Kamenogorsk","correspondingAuthor":false,"prefix":"","firstName":"Murat","middleName":"Mametkulovich","lastName":"Alimkulov","suffix":""},{"id":275943968,"identity":"5454d4ac-d6d6-4598-919c-bf70a81d2f60","order_by":3,"name":"MarzhanYessenbekovna Rakhymberdina","email":"","orcid":"","institution":"Ust-Kamenogorsk","correspondingAuthor":false,"prefix":"","firstName":"MarzhanYessenbekovna","middleName":"","lastName":"Rakhymberdina","suffix":""},{"id":275943969,"identity":"2535f688-0fd3-4c5e-a7cc-7867bb5957f8","order_by":4,"name":"Valeriy Chernavin","email":"","orcid":"","institution":"Ust-Kamenogorsk","correspondingAuthor":false,"prefix":"","firstName":"Valeriy","middleName":"","lastName":"Chernavin","suffix":""},{"id":275943970,"identity":"8c69040e-1bec-4aa8-93b3-3ebe6437fb16","order_by":5,"name":"Ayazhan Aitkazin","email":"","orcid":"","institution":"Ust-Kamenogorsk","correspondingAuthor":false,"prefix":"","firstName":"Ayazhan","middleName":"","lastName":"Aitkazin","suffix":""}],"badges":[],"createdAt":"2024-03-02 02:34:48","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4005194/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4005194/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":52040319,"identity":"f28ee260-09e2-46a8-8ac4-666cb74d4197","added_by":"auto","created_at":"2024-03-05 17:46:54","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":889677,"visible":true,"origin":"","legend":"\u003cp\u003eBreaking out of the welz-furnace lining\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4005194/v1/53f5e0c0cc1b24c96f3113b9.png"},{"id":52040317,"identity":"b356f7a8-084d-4676-862c-4882fb793c8d","added_by":"auto","created_at":"2024-03-05 17:46:54","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1981173,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4005194/v1/02d0b2633397cf13de9e9339.png"},{"id":52040318,"identity":"3c300e5c-3638-42ec-aae7-1e6fd7d4c242","added_by":"auto","created_at":"2024-03-05 17:46:54","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":576134,"visible":true,"origin":"","legend":"\u003cp\u003ePhotos of cube strength tests\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4005194/v1/1f2dd251c445c2d3aba24c24.png"},{"id":53449275,"identity":"bd79f837-d3eb-44b9-b7be-f4ec5bdeb346","added_by":"auto","created_at":"2024-03-26 06:13:17","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3303011,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4005194/v1/7df83fd0-24c9-4f7b-8ab3-7af86e31f83b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Experimental Studies of Heat Resistance and Compressive Strength of Heat-Resistant Concrete","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe increasing construction of various thermal units, as well as load-bearing structures operating in conditions of simultaneous exposure to high (constant and variable) temperatures and various aggressive environments, requires an increase in the production of heat-resistant and chemically resistant materials, the creation of new heat-resistant materials and the development of such building structures that would increase the service life of thermal units and apply industrial methods construction [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFluidized bed furnaces (hereinafter referred to as fluidized bed furnaces) are one of the units that operate under conditions of simultaneous exposure to constant high temperature and aggressive environment. Currently, fluidized bed furnaces are lined with fireclay refractories, [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe working chamber lining consists of a working layer made of fireclay refractory and a thermal insulation layer made of sheet asbestos. In the lower part of the chamber, the lining thickness is 3 bricks, in the upper part \u0026ndash; 0.5 bricks. To maintain the gas temperature sufficient to complete the particle oxidation process, the thermal insulation layer of the working chamber above the fluidized bed is additionally lined with lightweight fireclay or diatomaceous earth refractories (40\u0026ndash;70 mm thick with asbestos), [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe furnace bottom is made of heat-resistant concrete on liquid glass or Portland cement and is a plate or arch with a thickness of 200\u0026ndash;300 mm with holes for gas distribution nozzles. The furnace roof, the arched loading chamber, and the discharge chamber adjacent to the furnace wall are also lined with fireclay refractory [4[.\u003c/p\u003e \u003cp\u003eOne of the problems that arise during operation is the lack of compliance with the quality of work performed when lining fluidized bed furnaces. Currently, the shaft walls and the furnace dome are lined with category I fire-resistant masonry, and the furnace bottom is filled with heat-resistant concrete [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the process of operation of the furnace was identified deficiencies in the lining piece materials such as [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]: the structure of mastic density less than the density of the brick \u0026ndash; it leads to blowing mastic from the masonry joints; incorrect sequence of works is manifested in the fact that, you first need to fill the bottom of the furnace, and then is made masonry walls of the furnace stack, now do the opposite, resulting in the lining of the hearth furnace technology of the seam, in the process of operation of the furnace, at high temperatures, concrete can shrink, which leads to the formation of crack \u0026ndash; this in turn leads to the melting of the steel sheet of the base of the furnace, also, the defect violates the technological process of firing, due to the fact that the steel sheet hearth furnace took a bowl, there are additional areas between the liner and the steel furnace body, where it goes part of the air supplied to create a fluidized bed is a violation of the forced to serve a greater amount of air [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]; the absence or the insufficient size of the expansion joint between the liner and the steel furnace body, now as an expansion joint acts 1 sheet 5 mm thick asbestos cardboard that are glued to a steel furnace body, this event is not effective due to the low thickness of the expansion joint is that in winter, resulting in deformation, and in some cases the rupture of the steel casing of the furnace [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAll these disadvantages lead to disruption of the technological process of zinc production, which leads to a decrease in the concentration of SO\u003csub\u003e2\u003c/sub\u003e in the exhaust gases, leads to an increase in the amount of oxygen required for the oxidation reaction of zinc concentrates during the firing process and, as a result, a decrease in the quality of the resulting cathode zinc [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCurrently, one of the dominant issues facing non-ferrous metallurgy enterprises is to increase the productivity of fluidized bed roasting furnaces by increasing the lifetime of the furnace [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Therefore, to solve this issue, it is proposed to replace the traditional method of lining fluidized bed furnaces with piece materials fluidized bed with a monolithic concrete version, but for this it is necessary to prove that heat-resistant concrete meets the technological requirements of these furnaces [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The technological feature of fluidized bed furnaces is that the lining is simultaneously affected by high temperatures up to 1000\u0026deg;C and an aggressive environment caused by sulfur dioxide SO\u003csub\u003e3\u003c/sub\u003e. Of the known types of heat-resistant concretes, liquid glass concrete with the addition of sodium silicofluoride is both heat-resistant and chemical-resistant [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. It was this type of concrete that was chosen as the basis.\u003c/p\u003e \u003cp\u003eThe relevance of the chosen topic is to increase the productivity of fluidized bed furnaces by reducing downtime during repairs.\u003c/p\u003e"},{"header":"2. Main Part of Research","content":"\u003cdiv id=\"Sec3\"\u003e\n \u003ch2\u003e2.1 Materials and Methods\u003c/h2\u003e\n \u003cp\u003eHeat-resistant concrete is currently being used for the manufacture of prefabricated elements, as well as monolithic structures. Examples of its rational use in industry can be multi-pod furnaces for burning sulfur pyrite, coarse dust collectors and dust chambers, covers of the ABM-1.5A unit, lining of profitable superstructures, furnaces with a boiling (fluidized) layer, lining of trolleys of tunnel furnaces [\u003cspan\u003e12\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe developed design of the monolithic lining of the fluidized bed furnace is a cylindrical steel furnace body, glued with several layers of asbestos cardboard. Next comes a layer of monolithic heat-resistant concrete on liquid glass with structural reinforcement with grids in the walls and a spatial frame in a domed vault [\u003cspan\u003e13\u003c/span\u003e]. The hearth is filled with heat-resistant concrete, the role of reinforcement is performed by steel nozzles of the hearth [\u003cspan\u003e14\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe new design of the monolithic lining of fluidized bed furnaces was developed taking into account the requirements of regulatory documents of the Republic of Kazakhstan, and the requirements of foreign documents. Thus, the value of the concrete protective layer for reinforcement was determined in accordance with the requirements [\u003cspan\u003e5\u003c/span\u003e, \u003cspan\u003e15\u003c/span\u003e], and the results of scientific tests [\u003cspan\u003e16\u003c/span\u003e, \u003cspan\u003e17\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eA team of authors Bolshakov D. V., Bolshakov V. V., Nemtsev V. S., Goltsev A. G. obtained an innovative patent of the Republic of Kazakhstan for the developed design of a monolithic furnace lining under the number 28370.\u003c/p\u003e\n \u003cp\u003eA special feature of the composition of heat-resistant concrete is that in order to reduce the cost of the concrete mix, a broken brick of the SHCU brand from the fireclay zone of the refractory lining of the Welz furnace is used as a coarse and fine aggregate [\u003cspan\u003e18\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eBricks of the SHCU brand were crushed to a certain fraction in accordance with the interstate standard \u0026minus;\u0026thinsp;20910\u0026thinsp;\u0026minus;\u0026thinsp;2019.\u003c/p\u003e\n \u003cp\u003eThe main task of selecting the composition of heat-resistant concrete on liquid glass, is to choose such a ratio between fine and coarse aggregate, in which the binder consumption would be minimal in order to ensure minimal porosity and shrinkage of concrete, as well as high refractory properties of concrete [\u003cspan\u003e19\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe true total porosity of concrete on liquid glass depends on the true porosity of the aggregate, which is reduced to some extent due to impregnation with liquid glass, on the true porosity of the hardened binder and on the voids that have appeared in the concrete between the aggregate grains. Porosity is one of the most important characteristics of materials operating at high temperatures. As the porosity decreases, the strength of the material increases and its resistance to high temperatures and aggressive environments increases [\u003cspan\u003e20\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eIn addition to porosity, one of the main characteristics of heat-resistant concrete is temperature shrinkage, which mainly depends on the composition and amount of binder. The more binder is added to the concrete, the greater the shrinkage of the concrete. In this regard, to reduce shrinkage, it is necessary to reduce the consumption of binder in concrete. In most cases, the reduction in consumption is also due to its lower refractoriness compared to aggregates.\u003c/p\u003e\n \u003cp\u003eSelection of the composition of heat-resistant concrete производиwas made using the method proposed by F. I. Melnikov as a basis. The basic principle of calculating the composition of heat-resistant concrete on liquid glass is to ensure that the voids between the aggregate grains are filled with a binder dough in such a way that the necessary workability of the concrete mixture is obtained. The volume of the binder dough must be introduced into the concrete mix with some excess in comparison with the volume of intergranular space. This excess should correspond, first, to the volume that is necessary to ensure the workability of the concrete mix, and, secondly, to the volume that is absorbed into the pores when using a porous aggregate [\u003cspan\u003e21\u003c/span\u003e, \u003cspan\u003e22\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\"\u003e\n \u003ch2\u003e2.2 Mathematical Justification of the Research\u003c/h2\u003e\n \u003cp\u003eTo obtain aggregate mixtures with minimal voidness, dry mixtures of coarse and fine chamotte aggregate were prepared in different weight ratios. For each mixture, the bulk density was determined when compacting it on a vibrating platform. It was found that the highest bulk density of 1700 kg /m\u003csup\u003e3\u003c/sup\u003e corresponds to the ratio of fine and coarse fractions 65: 35 (%by weight), i.e. with a higher proportion of fine aggregate. However, experimental studies have shown that with a large flow rate of fine aggregate, the need for liquid glass increases significantly due to the large specific surface area of the aggregate [\u003cspan\u003e23\u003c/span\u003e]. Taking into account the consumption of liquid glass, it was found that the optimal ratio of fine and coarse aggregates is 40: 60. The average density of the mixture in this case is 1620 kg/m\u003csup\u003e3\u003c/sup\u003e. All calculations were performed according to the main methods set out in regulatory documents [\u003cspan\u003e24\u003c/span\u003e, \u003cspan\u003e25\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe consumption of aggregates (coarse and fine) per 1m\u003csup\u003e3\u003c/sup\u003e of concrete mix is determined by Eqs. (\u003cspan\u003e1\u003c/span\u003e)\u003c/p\u003e\n \u003cdiv id=\"Equ1\"\u003e\n \u003cdiv id=\"FileID_Equ1\" name=\"EquationSource\"\u003e$${P}_{a}=\\frac{1000}{\\frac{1}{{\\rho }_{a.d}}+\\frac{\\alpha \\cdot {К}_{exc}}{{\\rho }_{a}}}$$\u003c/div\u003e\n \u003cdiv\u003e1\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003ewhere: \u003cem\u003e\u0026rho;\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e aggregate consumption kg, \u003cem\u003e\u0026rho;\u003c/em\u003e\u003csub\u003e\u003cem\u003ea.d\u003c/em\u003e\u003c/sub\u003e apparent aggregate density t/m\u003csup\u003e3\u003c/sup\u003e, \u003cem\u003e\u0026alpha;\u003c/em\u003e voidness of the aggregate. \u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eexc\u003c/em\u003e\u003c/sub\u003e excess coefficient of the binder dough (taking into account the workability of the concrete mix, the excess coefficient can be assumed to be equal to 1.5. \u003cem\u003e\u0026rho;\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e average density of a mixture of fine and coarse aggregates t/m\u003csup\u003e3\u003c/sup\u003e (not in the compacted state).\u003c/p\u003e\n \u003cp\u003eThe consumption of coarse aggregate \u003cem\u003eK\u003c/em\u003e is determined based on the established optimal ratio of aggregates by Eqs. (\u003cspan\u003e2\u003c/span\u003e):\u003c/p\u003e\n \u003cdiv id=\"Equ2\"\u003e\n \u003cdiv id=\"FileID_Equ2\" name=\"EquationSource\"\u003e$$K={P}_{a}\\cdot k$$\u003c/div\u003e\n \u003cdiv\u003e2\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003ewhere \u003cem\u003ek\u003c/em\u003e is the percentage of a large placeholder.\u003c/p\u003e\n \u003cp\u003eThe consumption of fine aggregate \u003cem\u003eM\u003c/em\u003e is determined by Eqs. (\u003cspan\u003e3\u003c/span\u003e)\u003c/p\u003e\n \u003cdiv id=\"Equ3\"\u003e\n \u003cdiv id=\"FileID_Equ3\" name=\"EquationSource\"\u003e$$M=\\left({P}_{a}-K\\right)\\cdot \\left(1+\\text{g}\\right)$$\u003c/div\u003e\n \u003cdiv\u003e3\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003ewhere \u003cem\u003eg\u003c/em\u003e is the fraction of particles with a size of at least 0.14 mm in the fine aggregate.\u003c/p\u003e\n \u003cp\u003eThe voidness of the aggregate \u003cem\u003e\u0026alpha;\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e is determined experimentally or by the Eqs. (\u003cspan\u003e4\u003c/span\u003e)\u003c/p\u003e\n \u003cdiv id=\"Equ4\"\u003e\n \u003cdiv id=\"FileID_Equ4\" name=\"EquationSource\"\u003e$${\\alpha }_{a}=\\frac{{\\rho }_{a.d}-{\\rho }_{a}}{{\\rho }_{a.d}}$$\u003c/div\u003e\n \u003cdiv\u003e4\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003ewhere \u003cem\u003e\u0026rho;\u003c/em\u003e\u003csub\u003e\u003cem\u003ea.d\u003c/em\u003e\u003c/sub\u003e apparent density (or average density in a piece) of aggregate, t/m\u003csup\u003e3\u003c/sup\u003e \u003cem\u003e\u0026rho;\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e bulk density of aggregate t/m\u003csup\u003e3\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eThe consumption of a mixture of hardener and fine-ground additives for concrete on liquid glass is calculated by Eqs.\u0026nbsp;(\u003cspan\u003e5\u003c/span\u003e)\u003c/p\u003e\n \u003cdiv id=\"Equ5\"\u003e\n \u003cdiv id=\"FileID_Equ5\" name=\"EquationSource\"\u003e$$N=\\frac{{\\alpha }_{a}\\bullet {P}_{a}\\bullet {\\rho }_{\\text{f}}\\bullet {K}_{exc}}{{\\rho }_{a}}$$\u003c/div\u003e\n \u003cdiv\u003e5\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003ewhere \u003cem\u003eN\u003c/em\u003e is the mass of the mixture of finely ground additive and hardener kg, \u003cem\u003eР\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e total mass of small and large aggregates kg, \u003cem\u003e\u0026rho;\u003c/em\u003e\u003csub\u003ef\u003c/sub\u003e bulk density of the fine-ground additive t/m\u003csup\u003e3\u003c/sup\u003e, \u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eexc\u003c/em\u003e\u003c/sub\u003e coefficient of excess of astringent dough, \u003cem\u003e\u0026rho;\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e is the bulk density of a mixture of fine and coarse aggregates t/m\u003csup\u003e3\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eThe excess coefficient of astringent dough was determined experimentally. To do this, based on the calculation, test mixes were prepared with different coefficients of excess binder in the range of 1.2\u0026ndash;1.8, while the workability of the concrete mixture was also determined. As a result of the conducted studies, it was found that sufficient workability of concrete mixes was obtained with an excess coefficient of binder dough equal to 1.5.\u003c/p\u003e\n \u003cp\u003eThe flow rate of liquid glass should be determined by the Eqs.\u0026nbsp;(\u003cspan\u003e6\u003c/span\u003e)\u003c/p\u003e\n \u003cdiv id=\"Equ6\"\u003e\n \u003cdiv id=\"FileID_Equ6\" name=\"EquationSource\"\u003e$${Р}_{l}=\\left(\\frac{N}{{\\rho }_{f}}+\\frac{{Р}_{l}\\cdot W}{{\\rho }_{l}\\cdot 100}\\right)\\cdot {\\rho }_{l.\\text{g}}$$\u003c/div\u003e\n \u003cdiv\u003e6\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003ewhere \u003cem\u003eР\u003c/em\u003e\u003csub\u003e\u003cem\u003el\u003c/em\u003e\u003c/sub\u003e mass of liquid glass kg, \u003cem\u003eW\u003c/em\u003e water absorption of aggregates %, \u003cem\u003ep\u003c/em\u003e\u003csub\u003e\u003cem\u003el.g\u003c/em\u003e\u003c/sub\u003e density of liquid glass t/m\u003csup\u003e3\u003c/sup\u003e, \u003cem\u003ep\u003c/em\u003e\u003csub\u003ef\u003c/sub\u003e is the density of the fine-ground additive t/m\u003csup\u003e3\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eTo determine water absorption, take an average sample of 0.5 kg of aggregate fraction 2.5 mm, dried to a constant mass, placed in a vessel and filled with water at room temperature. After 2 hours of soaking, the water is drained through a sieve with holes of no more than 1.25 mm. The aggregate is lightly wiped with a pre-moistened and wrung out towel and weighed.\u003c/p\u003e\n \u003cp\u003ePartial water absorption,%, is calculated by Eqs.\u0026nbsp;(\u003cspan\u003e7\u003c/span\u003e)\u003c/p\u003e\n \u003cdiv id=\"Equ7\"\u003e\n \u003cdiv id=\"FileID_Equ7\" name=\"EquationSource\"\u003e$$W=\\frac{{Р}_{w}-Р}{Р}\\cdot 100$$\u003c/div\u003e\u003cdiv\u003e7\u003c/div\u003e\u003c/div\u003e\u003cp\u003ewhere \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003ew\u003c/em\u003e\u003c/sub\u003e mass of the aggregate saturated with water kg, \u003cem\u003eP\u003c/em\u003e mass of dry aggregate kg.\u003c/p\u003e\u003cp\u003eThe hardener consumption is determined by Eqs.\u0026nbsp;(\u003cspan\u003e8\u003c/span\u003e)\u003c/p\u003e\u003cdiv id=\"Equ8\"\u003e\u003cdiv id=\"FileID_Equ8\" name=\"EquationSource\"\u003e$$O=m\\cdot {P}_{l}$$\u003c/div\u003e\u003cdiv\u003e8\u003c/div\u003e\u003c/div\u003e\u003cp\u003ewhere \u003cem\u003eO\u003c/em\u003e is the mass of the hardener kg, \u003cem\u003em\u003c/em\u003e is the proportion of the hardener.\u003c/p\u003e\u003cp\u003eThe consumption of hardener is determined experimentally in the development of binder and concrete compositions, and it depends on the type of fine-ground additive. When using chamotte, its share is 0.1\u0026ndash;0.15 of the mass of liquid glass.\u003c/p\u003e\u003cp\u003eThe consumption of fine-ground additives is calculated by Eqs.\u0026nbsp;(\u003cspan\u003e9\u003c/span\u003e)\u003c/p\u003e\u003cdiv id=\"Equ9\"\u003e\u003cdiv id=\"FileID_Equ9\" name=\"EquationSource\"\u003e$$T=N\\cdot O$$\u003c/div\u003e\u003cdiv\u003e9\u003c/div\u003e\u003c/div\u003e\u003cp\u003ewhere \u003cem\u003eT\u003c/em\u003e is the weight of the fine-ground additive kg, \u003cem\u003eN\u003c/em\u003e mass of the mixture of finely ground additive and hardener kg, \u003cem\u003eO\u003c/em\u003e mass of the hardener kg.\u003c/p\u003e\u003cp\u003eFurther, the calculation of heat-resistant concrete on liquid glass was performed by Logunin and Sokov (2018), in the presence of the following materials: liquid glass with a density of 1.38, fireclay aggregate with a particle content of less than 0.14 mm in fine aggregate of 10%, water absorption of aggregate of 9%, fine-ground additive (mortar).\u003c/p\u003e\u003cp\u003eThe consumption of fine and coarse aggregates is determined from formula Eqs.\u0026nbsp;(\u003cspan\u003e1\u003c/span\u003e):\u003c/p\u003e\u003cp\u003e\u003cspan\u003e\u0026nbsp;\u003cspan\u003e\\({P}_{з}=\\frac{1000}{\\frac{1}{2}+\\frac{\\text{0,3}\\cdot \\text{1,5}}{\\text{1,35}}}=1200\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003e kg;\u003c/p\u003e\n \u003cp\u003eMass of coarse aggregate according to Eqs.\u0026nbsp;(\u003cspan\u003e2\u003c/span\u003e)\u003c/p\u003e\n \u003cp\u003e\u003cspan\u003e\u0026nbsp;\u003cspan\u003e\\(K=1200\\cdot \\text{0,6}=720\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003ekg;\u003c/p\u003e\n \u003cp\u003eMass of fine aggregate according to Eqs.\u0026nbsp;(\u003cspan\u003e3\u003c/span\u003e)\u003c/p\u003e\n \u003cp\u003e\u003cspan\u003e\u0026nbsp;\u003cspan\u003e\\(М=\\left(1200-720\\right)\\cdot \\left(1+\\frac{10}{100}\\right)\\approx 530\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003ekg;\u003c/p\u003e\n \u003cp\u003eThe voidness of the aggregate is determined by the Eqs.\u0026nbsp;(\u003cspan\u003e4\u003c/span\u003e)\u003c/p\u003e\n \u003cdiv id=\"Equa\"\u003e\n \u003cdiv id=\"FileID_Equa\" name=\"EquationSource\"\u003e$${\\alpha }_{з}=\\frac{2-\\text{1,35}}{2}\\approx \\text{0,32}$$\u003c/div\u003e\n \u003c/div\u003e; \u003cp\u003eThe consumption of fine-ground additive and hardener is found by the Eqs.\u0026nbsp;(\u003cspan\u003e5\u003c/span\u003e)\u003c/p\u003e\n \u003cp\u003e\u003cspan\u003e\u0026nbsp;\u003cspan\u003e\\(N=\\frac{\\text{0,32}\\cdot 1200\\cdot \\text{1,2}\\cdot \\text{1,5}}{\\text{1,35}}=511\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003e kg;\u003c/p\u003e\n \u003cp\u003eThe flow rate of liquid glass is calculated from Eqs.\u0026nbsp;(\u003cspan\u003e6\u003c/span\u003e)\u003c/p\u003e\n \u003cp\u003e\u003cspan\u003e\u0026nbsp;\u003cspan\u003e\\({Р}_{l}=\\left(\\frac{511}{\\text{2,65}}+\\frac{1200\\cdot \\text{0,09}}{\\text{1,35}}\\right)\\cdot \\text{1,38}=385\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003ekg;\u003c/p\u003e\n \u003cp\u003eThe consumption of sodium silicofluoride per 1m\u003csup\u003e3\u003c/sup\u003e of heat-resistant concrete according to formula (8) is 10\u0026ndash;15% of the mass of liquid glass, then\u003c/p\u003e\n \u003cp\u003e\u003cspan\u003e\u0026nbsp;\u003cspan\u003e\\(O=\\text{0,12}\\cdot 385=46\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003ekg;\u003c/p\u003e\n \u003cp\u003eThe consumption of the fine-ground additive according to Eqs.\u0026nbsp;(\u003cspan\u003e9\u003c/span\u003e) is\u003c/p\u003e\n \u003cp\u003e\u003cspan\u003e\u0026nbsp;\u003cspan\u003e\\(T=511-46=465\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003e kg.\u003c/p\u003e\n \u003cp\u003eThe consumption of materials per 1m\u003csup\u003e3\u003c/sup\u003e of heat-resistant concrete on liquid glass with fireclay aggregate using welz-furnace lining breakage is shown in Table \u003cspan\u003e1\u003c/span\u003e.\u003c/p\u003e\n \u003cdiv\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 1\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eMaterial consumption, kg per 1m\u003csup\u003e3\u003c/sup\u003e of heat-resistant concrete\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eName\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eConsumption, kg\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eLiquid glass\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e385\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eSodium silicofluoride\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e46\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eMortar\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e465\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eChamotte filler:\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003esmall\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e530\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003elarge\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e720\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eFigure\u0026nbsp;1 shows a broken welz furnace lining, a brick SHCU and a large aggregate made from it.\u003c/p\u003e\n \u003cdiv\u003e\n \u003c/div\u003e\n \u003c/div\u003e"},{"header":"3. Methods of Conducting Experimental Research","content":"\u003cp\u003eTo assess the quality of the fluidized bed furnace lining with heat-resistant monolithic concrete using secondary refractories, it is necessary to check experimentally, highlighting the main characteristics from a number of physical and mechanical properties of heat-resistant concrete. The fluidized bed furnace lining consists of a shaft with a height of 13 m, a diameter of 7.6 m and a dome arch with a lifting boom of 1.15 m. Therefore, to calculate the lining structure for load-bearing capacity, it is necessary to determine the compressive strength of concrete. In order to find out whether concrete can withstand the gradual heating and cooling associated with stopping the furnace for current and major repairs, it is necessary to determine its thermal resistance.\u003c/p\u003e\n\u003cp\u003eTo obtain a composition with a degree of reliability of P\u0026thinsp;=\u0026thinsp;0.9, for strength testing, in accordance with The interstate standard 20910\u0026thinsp;\u0026minus;\u0026thinsp;2019, it is necessary to produce at least 3 cubes with a rib height of 100 mm, for heat resistance testing, in accordance with the interstate standard 20910\u0026thinsp;\u0026minus;\u0026thinsp;2019, it is necessary to produce at least 3 cubes with a rib height of 70 mm.\u003c/p\u003e\n\u003cp\u003eExisting methods of testing for thermal stability are very imperfect, as they do not reflect the actual operating conditions of fluidized bed furnaces and other thermal units. Each heating unit has its own time period for heating and cooling, and cannot be equated with another unit. Also, not all types of heat-resistant concrete are resistant to cooling in an aqueous environment; for heat-resistant concrete on liquid glass, air cooling is necessary [\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eThe standard method for determining the thermal resistance of refractory materials for testing heat-resistant concrete on liquid glass is not applicable, since the destruction of concrete during testing can occur not only as a result of a sharp change in temperature, but also from the action of water on concrete.\u003c/p\u003e\n\u003cp\u003eTo determine the thermal resistance of heat-resistant concrete, a method was adopted in accordance with the interstate standard 20910\u0026thinsp;\u0026minus;\u0026thinsp;2019 in the Appendix 5 \u0026quot;Method for determining the heat resistance of concrete\u0026rdquo;, in which samples-cubes with a size of 70\u0026times;70\u0026times;70 \u003cem\u003emm\u003c/em\u003e are placed in a preheated oven to 800\u0026deg;C and kept at this temperature for 40 \u003cem\u003emin.\u003c/em\u003e Then the samples are removed from the furnace and cooled in an air stream (air cooling) to a temperature of 30\u0026ndash;50\u0026deg;C. After each heat change, the remaining cubes are examined and then the appearance of cracks, the nature of destruction and weight loss are noted. Then the cubes are placed back in the oven, kept at 800\u0026deg;C for 40 \u003cem\u003emin\u003c/em\u003e, and cooled in the above order. Heating and subsequent cooling of the cubes is carried out until the samples lose 20% of their original weight or until they are completely destroyed.\u003c/p\u003e\n\u003cp\u003eFor testing, two series of samples \u0026ldquo;1 from 12.07\u0026rdquo; and \u0026ldquo;4 from 16.07\u0026rdquo; were made from a given concrete composition. The series \u0026quot;1 from 12.07\u0026quot; consists of six cubes, the series \u0026quot;4 from 16.07\u0026quot; consists of three cubes. All cubes with an edge height of 70 and a mass from 630 to 710 g.\u003c/p\u003e\n\u003cp\u003eThe test progress is described below:\u003c/p\u003e\n\u003cp\u003e- when heated to 800\u0026deg;C, all cubes lost approximately 20 g in mass;\u003c/p\u003e\n\u003cp\u003e- when heated to 900\u0026deg;C, the cubes marked \u0026quot; 4 from 16.07\u0026rdquo; began to stick to the fireclay brick on which they were standing. After cooling, dark streaks and shallow depressions appeared, there were no noticeable mass losses (cubes \u0026ldquo;4 from 16.07 \u0026quot; were no longer tested). Cubes marked \u0026quot; 1 from 12.07\u0026rdquo; withstood 12 heat changes without significant changes and weight losses;\u003c/p\u003e\n\u003cp\u003e- when heated to 1000\u0026deg;C on the cubes marked \u0026ldquo;1 from 12.07\u0026rdquo;, dark streaks and small depressions appeared, there were no noticeable losses in mass.\u003c/p\u003e\n\u003cp\u003e- when heated to 1200\u0026deg;C, the cubes marked \u0026quot;1 from 12.07\u0026quot; melted, darkened and melted to the fireclay brick on which they stood.\u003c/p\u003e\n"},{"header":"4. Results and Discussions","content":"\u003cp\u003eAccording to the test results of two series of samples \u0026ldquo;1 from 12.07\u0026rdquo; and \u0026ldquo;4 from 16.07\", it is safe to say that the series \u0026ldquo;1 from 12.07\u0026rdquo; with the predominant number of cubes from two series, withstood 12 heat changes at a temperature of 900\u0026deg;C, which proves that it fully meets the requirements of heat-resistant concrete for heat resistance according to SN 156\u0026thinsp;\u0026minus;\u0026thinsp;67. A series of cubes \"4 from 16.07\" withstood a smaller number of heat changes at a temperature of 900\u0026deg;C, but at a temperature of 800\u0026deg;C, this series of samples showed good resistance indicators.\u003c/p\u003e \u003cp\u003eThe reason for the small number of heat changes in the series of samples \u0026ldquo;4 from 16.07\u0026rdquo; was the unsatisfactory quality of liquid glass in the composition of heat-resistant concrete. In the production of two series of cubes, liquid glass of different batches of cooking was used.\u003c/p\u003e \u003cp\u003eThe results of tests for determining heat resistance are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, photos are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e (a), (b) and (c).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThermal stability of heat-resistant concrete\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e№\u003c/p\u003e \u003cp\u003ep/p\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDimensions of samples, mm\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWeight of samples, g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eVolume weight of samples at the time of testing, kgs/m\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAge,\u003c/p\u003e \u003cp\u003eday\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNumber\u003c/p\u003e \u003cp\u003eof heat changes of the sample,\u003c/p\u003e \u003cp\u003eR\u003csub\u003ets\u003c/sub\u003e air, 900\u0026deg;C\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eAverage number of heat changes in a series of samples, R\u003csub\u003ets\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003eHeat-resistant concrete №1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e610\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1780\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003e12,5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e640\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1870\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e640\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1870\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e650\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1900\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e660\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1920\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e670\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1950\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003eHeat-resistant concrete №4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e640\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1870\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e1,3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e690\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2010\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e690\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2010\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo determine the compressive strength of concrete from a given concrete composition, two series of samples \u0026ldquo;2 from 13.07\u0026rdquo; and \u0026ldquo;3 from 13.07\u0026rdquo; were made, three cubes in each series with a rib height of 100 mm. The strength test was performed on a MS-500 press.\u003c/p\u003e \u003cp\u003eBefore starting the tests, the manufactured cubes were weighed and the actual dimensions of the sides were measured. After that, the cubes were placed under a press, where they were crushed to complete destruction [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe calculated value of the brand strength was determined by Eqs.\u0026nbsp;(\u003cspan refid=\"Equ10\" class=\"InternalRef\"\u003e10\u003c/span\u003e).\u003cdiv id=\"Equ10\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ10\" name=\"EquationSource\"\u003e\n$${R}_{b\\left(n\\right)}={R}_{b\\left(28\\right)}\\cdot \\frac{{ln}28}{{ln}n}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e10\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003eb(n)\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003eb(28)\u003c/em\u003e\u003c/sub\u003e are the ultimate strength of concrete after \u003cem\u003en\u003c/em\u003e and 28 days, kgs /cm\u003csup\u003e2\u003c/sup\u003e, ln \u003cem\u003en\u003c/em\u003e and ln 28 are decimal logarithms of the concrete age.\u003c/p\u003e \u003cp\u003eThe test results for determining compressive strength are shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, photos are shown in Fig.\u0026nbsp;3.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCompressive strength of heat-resistant concrete\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e№\u003c/p\u003e \u003cp\u003ep/p\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDimensions of samples,\u003c/p\u003e \u003cp\u003emm\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWeight of samples, g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eVolume weight of samples at the time of testing, kgs/m\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAge, day.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eStrength of samples during testing, kgs / cm\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eStrength of concrete\u003c/p\u003e \u003cp\u003eduring testing, kgs/cm\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eCalculated value of brand strength, kgs / cm\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"8\" nameend=\"c8\" namest=\"c1\"\u003e \u003cp\u003eHeat-resistant concrete №2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u0026times;99\u0026times;103\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1960\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1922\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e250,47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e270,45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e203,94\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e102\u0026times;100\u0026times;101\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1990\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1932\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e273,40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e105\u0026times;100\u0026times;101\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1995\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1881\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e267.49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"8\" nameend=\"c8\" namest=\"c1\"\u003e \u003cp\u003eHeat-resistant concrete №3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e104\u0026times;101\u0026times;102\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1990\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1858\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e262,90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e269,53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e203,25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e102\u0026times;101\u0026times;101\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1980\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1903\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e266,98\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e105\u0026times;100\u0026times;103\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1872\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e272,08\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e(a) two series of samples \u0026ldquo;2 from 13.07\u0026rdquo; (b) testing of samples on the MS-500 press\u003c/p\u003e \u003cp\u003eand \" 3 from 13.07\u0026rdquo;\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;3 Photos of cube strength tests\u003c/p\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eThe conducted experiment proved the possibility of using secondary refractory products as aggregates for heat-resistant concrete. This will allow using secondary refractories to reduce the cost of the concrete mix.\u003c/p\u003e\n\u003cp\u003eChanging the composition of concrete can improve its heat resistance and strength. It has been found that the addition of various additives, such as mixtures of second-use refractories, can increase the ability of concrete to withstand high temperatures without losing strength.\u003c/p\u003e\n\u003cp\u003eExperiments have shown that heat-resistant concrete can retain a significant part of its strength at high temperatures. However, when a certain temperature is reached, the material begins to lose strength due to changes. Under these conditions, the solution to the problem is to use liquid glass for a boiling furnace as a filling material, presented by the research experience.\u003c/p\u003e\n\u003cp\u003eExperimental data allow us to evaluate the behavior of concrete at different temperatures and give recommendations for its use in different conditions.\u003c/p\u003e\n\u003cp\u003eThe research results contribute to the creation of standards for heat-resistant concrete that help engineers and builders choose materials according to specific projects, taking into account the operating conditions, and are the optimal solution.\u003c/p\u003e\n\u003cp\u003eThe possibility of using heat-resistant concrete on liquid glass for lining fluidized bed furnaces has been proven, which is characterized by a number of advantages over lining the furnace with piece materials:\u003c/p\u003e\n\u003cp\u003e- reduction in the number or complete absence of masonry seams;\u003c/p\u003e\n\u003cp\u003e- increases the service life of the furnace due to the durability of the lining \u0026ndash; this is due to the fact that мthe monolithic lining has high strength characteristics and resistance in aggressive environments;\u003c/p\u003e\n\u003cp\u003e- reduces the repair time of the unit due to the high adhesive properties of heat-resistant concrete on liquid glass;\u003c/p\u003e\n\u003cp\u003e- faster commissioning of the unit due to rapid strength gain and accelerated drying modes.\u003c/p\u003e\n\u003cp\u003eThese results are important for developing more efficient building materials that can withstand extreme conditions and ensure the safety and durability of structures in a variety of environments.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAmkpa, Job \u0026amp; Badarulzaman, Nur Azam \u0026amp; Aramjat, Abu. 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IOP Conference Series: Materials Science and Engineering. 365. 032045. 10.1088/1757-899X/365/3/032045.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"fluidized bed furnace, heat-resistance concrete, fire-resistance concrete, lining, secondary refractories","lastPublishedDoi":"10.21203/rs.3.rs-4005194/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4005194/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe research purpose of the work is to extend the service life by experimental study of the performance of the liquid-layer furnace. Here, instead of large and small aggregates, the effect of the use of secondary refractory substances in reducing the cost of the concrete mixture is studied. The value of the study is to prove that heat-resistant concrete meets the technological requirements of a liquid-layer furnace, as well as experimental confirmation of the possibility of using secondary refractory materials as heat-resistant concrete aggregates. To solve this problem, it was proposed to replace the traditional method of facing the boiling floor furnaces (Fireclay brick of the SHB brand) with a monolithic concrete version. Considering that the technological feature of the boiling layer of the furnace is a high temperature up to 1000\u0026deg;C and an aggressive environment that causes SO\u003csub\u003e3\u003c/sub\u003e gaseous sulfur, one of the well-known types of heat-resistant concretes, the sodium-infused liquid glass concrete type is selected as the base, and instead of cement, it is recommended to use liquid glass with low thermal conductivity, such as a material in the amorphous phase and a glass-layered composite viscous substance.\u003c/p\u003e","manuscriptTitle":"Experimental Studies of Heat Resistance and Compressive Strength of Heat-Resistant Concrete","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-05 17:46:49","doi":"10.21203/rs.3.rs-4005194/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"66ca28a6-c2e6-49f7-aa0e-91f544876c0b","owner":[],"postedDate":"March 5th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-03-26T06:05:08+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-05 17:46:49","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4005194","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4005194","identity":"rs-4005194","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}