RU2657303C1 - Fine-grained concrete and method of the concrete mixture preparation for its production - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to the construction materials manufacturing, in particular to the fine-grained concrete and to the concrete mixture for its production preparation method, and can be used for manufacturing of the concrete products and structures, both monolithic and prefabricated, used in the building materials industry and construction, where the technology requires increased mixture fluidity at the application stage, and high strength of the fine-grained concrete. Produced from a concrete mixture including the Portland cement, quartz sand, filler, based on the “Melflux” polycarboxylate ether powdered hyper-plasticizer, water-retaining additive, water, the fine-grained concrete, as the Portland cement contains the Portland cement without additive with the cement paste normal density index of not more than 26 %, as the filler, micro-calcite with the calcium carbonate content of not less than 97 % with the fraction particles of not more than 120 mcm of not less than 98 % is used, including fractions of less than 20 microns – no more than 7 %, as the water-retaining additive, the condensed unconsolidated micro-silica is used with the amorphous silica content of at least 85 % and specific surface of 12–25 m²/g or metakaolin with the amorphous alumina content of at least 40 %, amorphous silica of not less than 50 %, aluminosilicate structure amorphisation of at least 90 % and specific surface of 1.2–2.5 m²/g in following ratio of components, mass%: Portland cement without additives with the cement paste normal density indicator of not more than 26 % – 15.8–23.6, quartz sand is 35.6–61.4, micro-calcite with the calcium carbonate content of not less than 97 % with the fraction particles of not more than 120 mcm of not less than 98 %, including fractions of less than 20 microns of no more than 7 % – 1.8–27.4, based on the “Melflux” polycarboxylate ether powdered hyperplasticizer – 0.14–0.30, condensed unconsolidated micro-silica with the amorphous silica content of at least 85 % and specific surface of 12–25 m²/g or metakaolin with the amorphous alumina content of at least 40 %, amorphous silica of not less than 50 %, aluminosilicate structure amorphisation of at least 90 % and specific surface of 1.2–2.5 m²/g – 0.81–4.20, water – the balance. In the concrete mixture for the fine-grained concrete production preparation method, consisting in the concrete mixture components successive mixing until the required fluidity and mobility is obtained, initially, the Portland cement and powdered hyperplasticizer are mixed in the mixer for 1–2 minutes, then the micro-calcite and water-retaining additive are filled in and mixed for 1–2 minutes, after which quartz sand is introduced and the dry mixture is stirred until uniformity for 1–2 minutes, then the first portion of water is introduced in an amount of 60–70 % and stirred for 1–2 minutes, at the final stage, adding the remaining portion of water in an amount of 30–40 % and mixing until the required mobility and uniformity concrete mixture is obtained.

EFFECT: invention is developed in subclaims.

9 cl, 3 tbl

Description

The invention relates to the production of building materials, in particular to fine-grained concrete and a method for preparing a concrete mixture for its production, and can be used for the manufacture of concrete products and structures, both monolithic and prefabricated, used in the building materials industry and construction, where technology is required increased fluidity of the mixture at the application stage and high strength of fine-grained concrete.

Known fine-grained concrete containing Portland cement, glauconite sand, filler - ground glauconite sand with a specific surface area S _beats = 350 m ² / kg, additive - superplasticizer S-3 and water [1].

A disadvantage of the known technical solution is the low strength of fine-grained concrete under compression at the design age.

Known fine-grained concrete obtained from a mixture containing Portland cement, aggregate - quartz sand with a fineness modulus of 2.7-3.2, silica-containing component - ground quartz sand with a specific surface S _beats = 500-700 m ² / kg, additives - hyperplasticizer " Melflux 2651 F "and antioxidant DSP, water [2].

A disadvantage of the known technical solution is the insufficiently high tensile strength in compression of fine-grained concrete at the age of 28 days, as well as the insufficiently high mobility of the concrete mixture, which does not allow abandoning vibration compaction in the manufacture of products from it.

The closest in technical essence to the claimed invention is sand concrete, obtained from a mixture including Portland cement, quartz sand with a particle size of 2.7-3.2, the filler is a chemical water treatment slurry (SHHVO) with a specific surface area of from 1200 to 1300 m ² / kg, Melflux 2651 F hyperplasticizer, water-holding additive in the form of silica fume, water [3].

A disadvantage of the known technical solution is the insufficiently high strength of sandy concrete under compression at the age of 28 days, the insufficiently high mobility of the self-compacting concrete mixture with the values of settlement and spreading of the standard cone not exceeding 25 and 60 cm, respectively, the need to use high-quality non-additive Portland cement M500 D0, as well as large quartz sand with a fineness modulus of 2.7-3.2, scarce in many regions of the Russian Federation.

A known method of preparing concrete with the addition of fibers, in which all concrete components are mixed to obtain concrete with the desired fluidity or dry components are first mixed, such as cement, various types of sand, ultra-small particles of calcium carbonate, white soot and, possibly, superplasticizer and anti-foam agent, after which water, and, if necessary, a superplasticizer, and anti-foam agent, if they are present in liquid form, and if necessary fibers, are added to the mixture and mixed until concrete with the required Match [4].

In the known solution, after mixing, for example, for 4-16 minutes, the resulting concrete can be easily molded due to its very high fluidity. The disadvantage of this method is the high consumption of cement for the preparation of 1 m ^{3 of the} mixture, which entails an increase in the cost of concrete and products from it, the need for self-compacting concrete with ultra-high properties of expensive sands from calcined bauxite and, mainly, high-grade white cements, such like Portland CEM I 52.5.

Closest to the technical nature of the claimed invention is a method of preparing a self-compacting particularly high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties, which consists in sequential mixing of the components to obtain a mixture of the desired yield. Initially, water and hyperplasticizer are mixed in the mixer, then cement, silica fume, stone flour are poured and the mixture is mixed for 2-3 minutes, after which sand and fiber are introduced and mixed for 2-3 minutes until a fiber-reinforced concrete mixture is obtained. The total preparation time of the concrete mixture is from 12 to 15 minutes [5].

The disadvantage of this method is the increased time for preparing the concrete mixture, comprising from 12 to 15 minutes, which complicates the process and increases the complexity of its production. In addition, the disadvantage of the known technical solution is the need to use high-quality non-additive Portland cement M500 D0 with its high consumption (27-31 wt.%), As well as the increased consumption of other expensive components of the mixture - silica fume and hyperplasticizer, which increases the cost of self-compacting especially high-strength reaction powder fiber-reinforced concrete mix and products from it.

The patent search did not allow us to find analogues with comparable strength indicators of fine-grained concrete at design age with comparable costs and activity (33-41 MPa) of Portland cement, as well as with a comparable method of preparing a mixture with high flow rates to obtain high-strength fine-grained concrete.

The technical result consists in increasing the compressive strength at the design (28 days) age of fine-grained concrete to the level of high-strength concrete with grade strength M500-M1000 and higher (class B40-B80 and higher), expanding the range of high-strength fine-grained concrete with the possibility of using it in their composition Portland cement of reduced grades (M300 and M400, activity 33-41 MPa), large quartz sand with a particle size modulus of at least 2.6, medium, small and very small quartz sand with a particle size modulus of 1.4-2.5, concrete cost reduction mixture to obtain high-strength fine-grained concrete by reducing the consumption of expensive components (Portland cement, hyperplasticizer, silica fume), increasing the volume of cement-mineral dough, reducing the complexity and increasing the efficiency of the preparation method, which allows to increase the fluidity of the concrete mixture to self-compacting mixtures with the standard cone precipitation values - at least 26-28 cm, the diameter of its spread is at least 64-75 cm and the diameter of the spread from the Hegermann cone is at least 250-300 mm.

The essence of the invention lies in the fact that fine-grained concrete obtained from a concrete mixture including Portland cement without additives with an index of normal density of cement paste of not more than 26%, silica sand, filler - microcalcite with a content of calcium carbonate CaCO _{3 of} not less than 97% are used with particles of fraction not more than 120 microns - not less than 98%, including fractions less than 20 microns - not more than 7%, powder hyperplasticizer based on polycarboxylate ether "Melflux", water-retaining additive - condensed silica fume uncompressed th content with amorphous silica SiO ₂ is not less than 85% and a specific surface area of 12-25 m ² / g or metakaolin with a content of amorphous alumina Al ₂ O ₃ is not less than 40% amorphous silica SiO ₂ - not less than 50%, amorphization aluminosilicate structure does not less than 90% and a specific surface area of 1.2-2.5 m ² / g and water, in the following ratio of components, wt. %:

Portland cement without additives normal density of cement paste not more than 26% 15.8-23.6 quartz sand 35.6-61.4 microcalcite containing calcium carbonate CaCO ₃ not less than 97% with particles of fraction not more than 120 microns - not less than 98%, including fractions less than 20 microns - not more than 7% 11.8-27.4 powder hyperplasticizer based polycarboxylate ether "Melflux" 0.14-0.30 fumed silica fume with the content of amorphous silica SiO ₂ not less than 85% and specific surface area 12-25 m ² / g or metakaolin with the content of amorphous alumina Al ₂ O ₃ not less than 40%, amorphous silica SiO ₂ - not less than 50%, amorphization of the structure of aluminosilicate at least 90% and specific surface area 1.2-2.5 m ² / g 0.81-4.20 water rest

Portland cement without additives with an index of normal density of cement paste of not more than 26% is used with an activity of 33-41 MPa.

Quartz sand with particles of fraction less than 0.63 mm can be used with a particle size module of 1.4-1.5. Quartz sand with particles of a fraction of not more than 5 mm can be used with a particle size modulus of 1.4-2.5. Quartz sand with particles of a fraction less than 0.63 mm with a content of not more than 37%, fractions of 0.63-5 mm - not less than 63% can be used with a particle size modulus of at least 2.6.

Microcalcite with a calcium carbonate content of CaCO _{3 of} at least 97% is used with particles of a fraction of not more than 120 microns - not less than 98%, including fractions of less than 20 microns - not more than 7%, can be used additionally with particles of a fraction of not more than 60 microns - not less than 50%.

Polycarboxylate ether powder hyperplasticizer can be used with the Melflux 5581 F grade.

The technical result is also achieved due to the method of preparation of concrete mixture to obtain fine-grained concrete, which consists in sequential mixing of the components of the concrete mixture. Initially, Portland cement and powder hyperplasticizer are mixed in the mixer for 1-2 minutes, then microcalcite and a water-retaining additive are poured and mixed for 1-2 minutes, then quartz sand is introduced and the dry mixture is mixed until homogeneous for 1-2 minutes, then introduced the first portion of water in an amount of 60-70% and stirred for 1-2 minutes, at the final stage, add the remaining portion of water in an amount of 30-40% and mix until a concrete mixture of the required mobility and uniformity is obtained. The total time for preparing the concrete mixture is from 10 to 12 minutes (this time includes additional operations for filling the components).

For the manufacture of fine-grained concrete compositions in accordance with the invention, the following were used:

- Portland cement of classes CEM I 32.5B and NEM I 42.5B and a normal density of 25-26% of the production of Mordovcement OJSC, GOST 31108-2003 "Cement for general construction. Technical conditions. " In order to optimize the consumption of cement in the compositions and correctly compare the properties of the binders of the invention and prototypes [3, 5] before the manufacture of concrete mixtures, the activity of the binder was evaluated in accordance with GOST 310.4-81 “Cements. Methods for determining the tensile strength in bending and compression ", as a result of which the studied parameter for the first and second types of Portland cement was 33 and 41 MPa, which corresponds to the grades of ПЦ 300 Д0 and ПЦ 400 Д0, GOST 10178-85" Portland cement and slag Portland cement. Technical conditions ";

- Natural quartz sand of the Novostepanovsky quarry of the Republic of Mordovia with particles no more than 5 mm in size, particle size 1.6 and dust and clay particles 1.6%, GOST 8736-2014 “Sand for construction work. Technical conditions. " As a result of sand fractionation and selection of fractions less than 0.63 mm and 0.63-5 mm, the particle size modulus varied in the range 1.4–2.6;

- Fine filler to increase the content of the dispersed phase of the binder - microcalcite KM 100 of the company LLC Polypark (Moscow) according to GOST R 56775-2015 and TU 5743-002-63925093-2009 with the content of calcium carbonate CaCO ₃ - 97-98% and the following particle size distribution: the largest particle size (d 98%) is 120 microns, the average particle size (d 50%) is 30-60 microns, particles less than 20 microns in size - not more than 7%;

- Melflux 5581 F brand hyperplasticizer - a powder product obtained by spray drying based on a modified polyester carboxylate, manufactured by BASF Construction Solutions (Trostberg, Germany);

- Microsilica fused uncompacted (MK-85) manufactured by JSC "Kuznetskiye ferroalloys", Novokuznetsk TU 5743-048-02495332-96 with a silica SiO ₂ 85-92%, a specific surface area of 12-25 m ² / g and the following particle size distribution: particles less than 2.0 microns - 90%, average particle size - 0.2 microns;

- Highly active white metakaolin produced by Sinergo LLC (VMK-40), Magnitogorsk according to TU 572901-001-65767184-2010 with amorphization of the aluminosilicate structure at the level of 90-92% and the content of basic oxides: Al ₂ O ₃ - 43.8 %, SiO ₂ - 53.4%; specific surface area -1.2-2.5 m ² / g; the average particle size of 2.0 microns;

- Water for concrete and mortar according to GOST 23732-2011.

To determine the mobility of the concrete mixture after preparation in accordance with the method of the invention, its spread from the Hegermann cone according to GOST 310.4-81 “Cements. Methods for determining the strength in bending and compression ”for comparison with the same indicator of mixtures of the prototype [5]. In addition, the sediment and the spread of fine-grained concrete mixtures of the invention from a standard cone according to GOST 10181-2014 “Concrete mixtures. Test methods "for comparison with a similar indicator of mixtures of the prototype [3]. A comparison of the methods of preparing the concrete mixture to obtain fine concrete of the invention and the prototype [5] are presented in table. one.

After the concrete mixture was prepared, fine-grained concrete products and control samples were made in accordance with GOST 10180. Samples were stored under normal conditions until the design age of 28 days (temperature 20 ± 2 ° C, relative humidity of the air not less than 90% created in the normal hardening chamber). Tests of samples with determination of compressive strength were carried out at the age of 28 days.

The compositions of the proposed fine-grained concrete and sand concrete of the prototype [3] are presented in table. 2. The test results of these compositions are presented in table. 3.

The viscosity index, as for [3], was determined through the time of expiration of the concrete mixture from the inverted standard cone using the indirect method T 500 [6].

The water separation and density of the concrete mixture were determined in accordance with the requirements of GOST 10181-2014, and the tensile strength of control samples under compression was determined in accordance with GOST 10180-2012.

The volume of the cement-mineral test of the concrete mixture was determined in accordance with [3]. The compositions of cement-mineral dough without sand were prepared, in which the consumption of cement and fillers was the same as for concrete mixtures, and the amount of water was adjusted taking into account the water demand of the sand. After preparation, the mixture was poured into a special measuring container in which the volume of the mixture was determined. A characteristic fact was the lack of water separation of concrete mixtures.

As can be seen from the table. 3, the mobility of the concrete mixture according to the proposed recipe with Hegermann cone melt 250-305 mm, standard cone draft (OK) 26-28 cm (mobility grade according to GOST 7473-2010 - P5) and its melt (RC) 64-75 cm above the mobility of the prototype [3] with a brand of mobility P5 (maximum OK in [3] - 25 cm, RK - 60 cm). According to [7], the proposed compositions No. 5-11 can be attributed to true self-flowing mixtures with a cone draft of at least 26 cm and a spreading diameter of at least 55 cm. In addition, the compositions of fine-grained concrete No. 5-7, 9, 11 with an index of RK 70- 75 cm, with a characteristic of T 500 2.5-3.0 sec and a total expiration time of 57-65 sec meet the requirements for self-compacting concrete mixtures of one of the European methods [6]. According to its requirements: the maximum diameter of the cone of the Republic of Kazakhstan for self-compacting concrete mixtures should be at least 70 cm, the time to reach a diameter of 500 mm (characteristic T 500) should not exceed 3-6 seconds, and the total spreading time should be at least 45 seconds.

High rheotechnological parameters of self-compacting fine-grained concrete mixtures are due to the method of their preparation for producing fine-grained concrete of the invention (Table 1), the proposed formulation (Table 2), characterized by an increased volume of cement-mineral dough (Table 3), as well as improved compatibility of filler-microcalcite with powder polycarboxylate hyperplasticizer Melflux compared with the SHHVO prototype [3]. Despite the higher cement consumption, the use of fractions of less than 0.63 mm with a fineness modulus of 1.4 in compositions No. 8 and 10 compared to composition No. 5, which also contains larger sand fractions (0.63-5 mm), to reduce the volume of cement-mineral dough due to the increased water demand of very fine sand.

Due to the fact that self-compacting concrete mixtures with a large number of finely dispersed components are prone to delamination and water separation, ultrafine mineral additives were introduced into the compositions: condensed silica fume (85-92% SiO ₂ , specific surface 12-25 m ² / g, average size particles - 0.2 μm), which is a waste product of the production of silicon-containing alloys, as well as aluminosilicate metakaolin (43.8% - Al ₂ O ₃ , 53.4% - SiO ₂ , specific surface area - 1.2-2.5 m / g , the average particle size of the plate form is 2.0 μm), resulting in ltate high temperature firing kaolinitic clays.

The use of microcalcite with a particle size distribution as a carbonate filler: the largest particle size (d 98%) is 120 microns, the average particle size (d 50%) is 30-60 microns, particles less than 20 microns in size - not more than 7%, allows to achieve high indicators of mobility and strength of concrete mix and concrete. A change in the dispersion of microcalcite negatively affects the mobility of the mixture and the strength characteristics of concrete. An increase in dispersion beyond this interval leads to an increase in the water demand of the mixture; its decrease contributes to the separation and separation of water in the mixture. This range of dispersion of the filler allows you to get stable results without compromising the properties of the concrete mixture and concrete.

High physical and mechanical properties of fine-grained concrete are due to the balanced particle size distribution of the components used. It is known that the most favorable small aggregates for the production of high-strength concrete, including those using self-compacting mixtures, are quartz sands with a fineness modulus of more than 2.0-2.1 [8]. At the same time, the use of fine and very fine sands, widespread in the Russian Federation, with a particle size modulus of up to 1.5-2.0 is constrained by a number of factors: a decrease in strength when using these sands (up to 2-3 times), increased voidness and specific surface area of sand requiring increased consumption of cement to maintain workability of concrete mix and strength characteristics of concrete [9]. The proposed technical solution allows the use in the recipe including medium, fine and very fine quartz sands with a particle size modulus of 1.4-2.5 without reducing the rheotechnological and strength indicators.

The use of silica fume (average particle diameter 0.2 μm) and metakaolin (2.0 μm) as a water-retaining additive can effectively fill the voids between the grains of cement (average diameter 30 μm). At the same time, there remains a large gap in the particle size distribution of mineral particles during the transition from cement to fine aggregate (sand), characterized mainly by particles of 0.16-0.63 mm or 0.16-5 mm. The use of a micro-filler in the form of ground marble with an intermediate dispersion (20-120 μm) allows you to fill the voids at this level of microstructure and, accordingly, more effectively use the prescription potential of the cementing properties of cement and additives. Thanks to the tight packing of the components of the concrete mixture, the air from it was displaced as much as possible.

Using the above components while observing the specified proportion in the quantitative ratio, the sequence of their introduction and the mixing time allows you to get a self-compacting fine-grained concrete mixture with high rates of fluidity and mobility when it diffuses from the Hegermann cone (form cone from the shaking table, GOST 310.4) not less than 250 -300 mm. It should be noted that going beyond the minimum and maximum quantitative limits of the content of the ingredients of the proposed fine-grained concrete compositions, as well as using a different method of preparing the concrete mixture to obtain fine-grained concrete compared to the proposed, the claimed technical result will not be achieved.

Compared with the known solution, the proposed method for preparing a concrete mixture for producing fine-grained concrete allows to reduce the cost of the mixture and thereby increase its consumer properties by reducing the consumption of Portland cement to 15.8-23.6 wt. % and other expensive components, in particular hyperplasticizer and silica fume. In addition, the cooking method allows to reduce the total time of its preparation while maintaining high flow characteristics and mobility of the mixture.

A distinctive feature of the method of preparing the concrete mixture to obtain fine-grained concrete is a two-stage portioned water mixing of the mixture. Moreover, the increase in the rheological effect of the proposed method for the preparation of mixtures is described in [10] and is associated with a mismatch in the balance of structural and free water in one-stage and two-stage water replenishment, as well as with the concept of a critical concentration of structure formation. If the dispersion phase is closed once with an excess amount of water, when the concentration of the solid phase is lower than critical, the particles of mineral powders tend to form cluster structures and “trap” an excess amount of liquid into the bulk structure due to a significant tendency to aggregation and structure formation. Macrocluster structures containing free water in their cells can be preserved when the water-mineral system is mixed, since an excess amount of inter-aggregate water reduces friction between the aggregates when applying flow deformation.

With two-stage water filling with a lack of water, more durable aggregates with a lower water content are formed in the first stage. The energy of shear deformation is fully realized by the destruction of large aggregates during mixing and their transformation into smaller and stronger ones. The residual water introduced into the second stage replenishes the balance of the aggregate fluid, which determines the rheological properties of disperse systems. Such a redistribution of mixing water leads to a decrease in friction between the aggregates and reduces the viscosity of water-dispersed compositions.

Another distinctive feature of the method of preparing the concrete mixture for producing fine-grained concrete of the invention from the prototype [5] is the discrete distribution of the powdered hyperplasticizer when it is mixed with the mineral phase in comparison with the introduction of a diluent through the prototype solution, which leads to a change in the mechanisms of adsorption.

Adsorption in cramped conditions (at water contents not exceeding 20-30 wt.%) Does not provide complete surface overlap along the initially contacting active centers and, as a result, the maximum dispersion of aggregates is not achieved in the preparation of highly concentrated systems. The process of adsorption from a solution has a filtration character in case of deficiency, with incomplete wetting of the ion exchanger with a limited amount of ionic solution and, as a result, polymolecular adsorption of the superplasticizer in the local hydration region. When mixing and averaging the dispersion, particles saturated with adsorbed hyperplasticizer give part of it to other particles, and the water filtered from the diluent is sorbed on free surfaces, causing coagulation of the particles. Thus, at low water contents, with the introduction of a hyperplasticizer through a solution, most mineral systems do not form highly aggregate-resistant dispersions. The method of pre-adsorption dry deposition of hyperplasticizer by discrete distribution by mixing with the mineral phase significantly increases the aggregate stability of mineral systems, as well as the water-reducing, concentration and rheological effects of the thinner [11].

The optimally selected chemical-mineralogical and granulometric composition of the components of the present invention contributed to the production of self-compacting fine-grained concrete mix with high rates of fluidity and mobility, denser packing of components, lower porosity of the structure of fine-grained concrete, and also helped to increase the strength characteristics of concrete at the design age. The use of medium and fine sands, as well as non-overactive Portland cements, will make it possible to use available local materials common in many regions of the Russian Federation in the formulation of fine-grained concrete, and thereby expand their nomenclature.

Thus, in comparison with the known technical solutions, the present invention allows to increase the compressive strength at the design (28 days) age of fine-grained concrete to the level of high-strength concrete with graded strength M500-M1000 and higher (class B40-B80 and higher), to expand the range of high-strength fine-grained concrete with the possibility of using Portland cement of reduced grades (activity 33-41 MPa), large quartz sands with a fineness modulus of at least 2.6, medium, small and very small quartz sands with with a particle size range of 1.4-2.5, reduce the cost of concrete mixture to obtain high-strength fine-grained concrete by reducing the consumption of expensive components, increase the volume of cement-mineral dough, reduce the complexity and increase the efficiency of the preparation method, which improves the fluidity of the concrete mixture to the performance of self-compacting mixtures with a standard cone draft of at least 26-28 cm, a diffusion diameter of at least 64-75 cm, and a Hegermann cone diameter of at least 250-300 mm.

Information sources

1. RU 2358938, IPC С04В 28/04, publ. 06/20/2009.

2. RU 2473493, IPC C04B 28/04, C04B 111/20, publ. 01/27/2013.

3. RU 2569947, IPC С04В 28/04, С04В 18/04, С04В 24/24, С04В 103/46, publ. 12/10/2015.

4. RU 2359936, IPC С04В 28/04, С04В 111/20, С04В 111/62, publ. 06/27/2009, paragraph 12 of the claims.

5. RU 2531981, IPC С04В 28/04, С04В 111/20, publ. 10/27/2014, p. 1, 2 claims.

6. Bolotskikh ON Self-compacting concrete and its diagnosis // Concrete Technologies. 2008. No. 10. S. 28-31.

7. Kalashnikov V.I. The calculation of the compositions of high-strength self-compacting concrete // Building materials. 2008. No. 10. S. 4-6.

8. Borisov A.A., Polyakov L.G., Viktorov V.V., Gorbunova B.C., Fomina L.V. Features of the selection of materials in the development of compositions and technology of high-strength concrete // Building materials. 2001. No.6. S. 28-29.

9. Lvovich K.I. Sand concrete and its use in construction. St. Petersburg: Stroy-Concrete, 2007.320 s.

10. Bazhenov Yu.M., Demyanova B.C., Kalashnikov V.I. Modified high quality concrete. - M.: Publishing house of the Association of construction universities, 2006. 368 p.

11. Kalashnikov V.I. Fundamentals of plasticization of mineral disperse systems for the production of building materials: dis. ... Dr. tech. sciences. Voronezh, 1996.89 s.

Claims (10)

1. Fine-grained concrete obtained from a concrete mixture including Portland cement, quartz sand, a filler, a Melflux polycarboxylate ether powder hyperplasticizer, a water-retaining additive, water, characterized in that Portland cement is used as a Portland cement without additives with an indication of normal density of the cement paste more than 26%, microcalcite with a calcium carbonate content of not less than 97% with particles of a fraction of not more than 120 microns - not less than 98%, including fractions of less than 20 microns - is used as filler not more than 7%, condensed unconsolidated silica fume with an amorphous silica content of at least 85% and a specific surface area of 12-25 m ² / g or metakaolin with an amorphous alumina content of at least 40%, amorphous silica - at least 50% is used as a water-holding additive amorphization of the structure of aluminosilicate at least 90% and a specific surface area of 1.2-2.5 m ² / g in the following ratio of components, wt. %: Portland cement without additives with an indicator of normal density of cement paste not more than 26% 15.8-23.6 quartz sand 35.6-61.4 microcalcite with calcium carbonate not less than 97% with particles of fraction not more than 120 microns - not less than 98%, including fractions less than 20 microns - not more than 7% 1.8-27.4 powder hyperplasticizer based polycarboxylate ether "Melflux" 0.14-0.30 fumed silica fume with amorphous silica content of at least 85% and specific surface area 12-25 m ² / g or metakaolin with amorphous alumina content of at least 40%, amorphous silica - not less than 50%, amorphization structure of aluminosilicate at least 90% and specific a surface of 1.2-2.5 m ² / g 0.81-4.20 water rest 2. Fine-grained concrete obtained from the mixture according to claim 1, characterized in that Portland cement without additives is used with an activity of 33-41 MPa. 3. Fine-grained concrete obtained from the mixture according to claim 1, characterized in that quartz sand with particles of a fraction of less than 0.63 mm is used with a particle size modulus of 1.4-1.5. 4. Fine-grained concrete obtained from the mixture according to claim 1, characterized in that quartz sand with particles of a fraction of not more than 5 mm is used with a particle size module of 1.4-2.5. 5. Fine-grained concrete obtained from the mixture according to claim 1, characterized in that quartz sand with particles of a fraction of less than 0.63 mm with a content of not more than 37%, fractions of 0.63-5 mm - not less than 63% are used with the fineness modulus not less than 2.6. 6. Fine-grained concrete obtained from the mixture according to claim 1, characterized in that microcalcite with a calcium carbonate content of at least 97% is used with particles of a fraction of not more than 120 microns - not less than 98%, including fractions of less than 20 microns - not more than 7%, used additionally with particles of a fraction of not more than 60 microns - not less than 50%. 7. Fine-grained concrete obtained from the mixture according to claim 1, characterized in that the powder hyperplasticizer based on polycarboxylate ether "Melflux" use the brand "Melflux 5581 F". 8. The method of preparing the concrete mixture to obtain fine concrete according to paragraphs. 1-7, which consists in sequentially mixing the components of the concrete mixture to obtain the desired fluidity and mobility, characterized in that initially Portland cement and powder hyperplasticizer are mixed in the mixer for 1-2 minutes, then microcalcite and a water-retaining additive are poured and mixed for 1-2 min, after which quartz sand is introduced and the dry mixture is mixed until homogeneous for 1-2 minutes, then the first portion of water is introduced in an amount of 60-70% and mixed for 1-2 minutes, at the final stage d bavlyayut remaining portion of the water in an amount of 30-40% and stirred to give the required mobility of the concrete mix and homogeneity. 9. A method of preparing a concrete mixture to obtain fine concrete according to claim 8, characterized in that the total time for preparing the concrete mixture is from 10 to 12 minutes.

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