RU2210552C2 - Concrete mix - Google Patents

Abstract

FIELD: manufacture of building materials. SUBSTANCE: concrete mix for manufacturing high- quality concretes in fabrication of ferroconcrete items for underground tunnel construction and hydroengineering structures includes, wt +ACU-: as binding component, low-aluminate additive-free Portland cement M500, 17.97-18,23+ADs- broken granite fraction 5-10 mm, 17.97-18.24, and 10- 29 mm, 29.79-31.00+ADs- sand, 28.69-30.49+ADs- superplasticizer C-3, 0.076-0.136+ADs- mineral component (hermetic), 0.76-1.36+ADs- and water, the balance. Portland cement contains tricalcium aluminate in amount 4-7+ACU- of the weight of binder. Sand is, more particularly, river sand with fineness modulus 2-3. Ratio tricalcium aluminate (in Portland cement)/superplasticizer/hermetic is 10: 1: 10. EFFECT: intensified concrete strength growth in early stage and reduced expenses. 2 tbl

Description

 The invention relates to building materials, in particular to compositions of concrete mixtures for the manufacture of high-quality reinforced concrete products of underground and hydraulic engineering.

 Known [Batrakov V. G. Modified Concretes. - M .: Stroyizdat. - 1990 - p. 139] concrete mixtures for the manufacture of concrete with compression strength at 28 days of age up to 50 MPa, containing Portland cement, high-strength aggregate, sand, an additive in the form of superplasticizer and water, and also with compression strength at the age of 28 days up to 65 MPa [ibid. from. 201]. The water resistance of such concrete after 28 days of normal storage reaches the brand W12 [ibid, p. 223].

 The disadvantage of an analogue is the lack of strength and waterproofness of concrete.

Known concrete mixture [Scheinfeld A.V. Concretes of increased strength and impermeability on Portland cement with the addition of silica fume of various ferroalloy industries. Specialty 05.23.05. Abstract. dis. Cand. tech. Sciences, 04.9.10 01923, Moscow, 1991, p.109] for the preparation of high-quality concrete, including Portland cement M400, two-fraction granite crushed stone, river sand, S-3 superplasticizer, mineral component in the form of silica fume and water, the rest with the following ratio of components:
Portland cement M400 - 16.75-18.55
Granite crushed stone - 45.34-46.70
Sand of the river - 26.39-27.21
Superplasticizer S-3 - 0.16-0.41
Silica fume MK - 1.85-3.35
Water - Else
The disadvantage is the high cost and scarcity of silica fume, as well as the complexity of its delivery. In addition, concretes with MK in their composition are not sufficiently intensive in building strength at an early age.

 The prototype of the invention is a concrete mixture for the manufacture of high-quality concrete in the production of reinforced concrete products for underground tunneling and hydraulic structures, including binder Portum cement M500, granite crushed stone fractions of 5-10 mm and 10-20 mm, sand, S-3 superplasticizer, as a binder. component and water [RU 2058952, C 04 V 7 / 02-04, publ. 04/27/1996, 81с.].

 The disadvantage of the prototype is the lack of strength and complexity of the preparation of concrete mix.

 The invention is aimed at intensifying a set of high-quality concrete strength, especially at an early age and reducing the cost of manufacturing concrete while maintaining a high waterproof grade.

The result is achieved in that in the concrete mix for the manufacture of high-quality concrete in the production of reinforced concrete products for underground tunneling and hydraulic structures, including low-aluminate additive-free Portland cement M500, granite crushed stone fractions of 5-10 mm and 10-20 mm, sand, C- superplasticizer 3, the mineral component and water, said Portland cement contains C ₃ A tricalcium aluminate in an amount of 4-7 wt.% Of the binder, river sand with a particle size of 2-3 is used as sand, and as a mineral component, the Aquatron-6 sealant, and the ratio of the content of tricalcium aluminate, C ₃ A in Portland cement to the content of C-3 and the Aquatron-6 sealant is determined by the formula C ₃ A: C-3: "Aquatron-6" = 10: 1: 10 in the following ratio of components wt.%:
Portland cement M500 - 17.97-18.23
Granite crushed stone. fr. 5-10 mm - 14.24-15.25
Granite crushed stone 10-20 mm - 29.79-31.00
Sand of the river - 28.69-30.49
Superplasticizer S-3 - 0.076-0.136
Sealant "Aquatron-6" - 0.76-1.36
Water - Else
Characteristics of the components.

As the initial components for the preparation of the concrete mixture recommended in the present invention, non-additive Portland cement of the “500” grade of the Volsky, Staro-Oskolsky and Sebryakovsky plants with the corresponding content of C ₃ A - 4%, 7 and 5.5% (GOST 10178-85) was used.

 Granodiorite crushed stone of the Shershninsky deposit (Ural) fr. 5-20 mm, corresponding to GOST 8267-93, which was previously fractionated into two fractions of 5-10 and 10-20 mm.

 Fine aggregate - river quartz sand with a particle size modulus of 2.5–3 of the Kama-Ustinsky quarry RT (GOST 8736-93).

 Superplasticizer S-3 (TU 6-36-02042229-625-90) was used in dry powder form, from which an aqueous solution of a given density was then prepared.

The Aquatron-6 sealant (Biysk, Polyex), which meets the requirements of TU 75 080 05.080-97, was used as the mineral component. "Aquatron-6" belongs to the family of sealants for various purposes, manufactured by Polyex OJSC. This is a gray powder, which is a mixture of high-quality Portland cement and specially prepared quartz sand with regulated granulometry and modifying additives. Setting time: start - not later than 2 hours, end - not later than 5 hours, average density - 2.3 g / cm ³ . In addition, it is a multicomponent composite, which also includes inorganic salts - nitrates, sulfates of alkali and alkaline earth metals and other compounds.

 The technology for preparing the concrete mixture consists in pre-weighing the components, mixing in the laboratory mixer a gravel of fractions 5-10 and 10-20 mm, sand, cement and Akvatron-6 sealant in dry form until a uniform color is obtained, followed by adding 2/3 of the mixing water and re-mixing. After 100-120 seconds, the remaining 1/3 of the water is introduced along with the addition of a superplasticizer in the form of a 10% solution. The total mixing time is 3 minutes. Then conduct a standard definition of mobility and average density of compacted concrete mix.

The prepared mixture is placed in standard cubes of 10 • 10 • 10 cm, compacted on a vibrating plate and kept under normal conditions at a temperature of 20 ^o C and a humidity of 95%.

 Examples of compositions in the proposed concrete mixture are given in table. 1. Physico-mechanical properties of concrete of the proposed compositions are given in table. 2.

The introduction of the Aquatron-6 sealant into the concrete mix contributes to the formation of a denser waterproof structure of concrete, as when interacting with water, inorganic salts of the sealant's mineral acids form stable crystalline hydrates, which block the progress of the liquid through the capillaries. The introduction of "Aquatron-6" into the mixture leads to a change in the phase composition and pore structure of the concrete cement stone as a result of the formation of low-basic calcium hydrosilicates of the CSH type. This leads to a redistribution of differential porosity: a decrease in the number of capillary pores (with a diameter of 5 • 10 ^-3 -4 • 10 ^-1 microns) and an increase in the number of pores of the gel (with a diameter of 1 • 10 ^-3 -5 -5 • 10 ^-3 ), which is also a consequence increase the degree of hydration. The combined effect of three factors: C ₃ A, C-3 and Aquatron-6, contributes even more to the formation of an impermeable concrete structure.

It has been experimentally proved that, while observing the ratio of the content of C ₃ A in the mineralogical composition of Portland cement clinker to the content of C-3 (wt.%) And Aquatron-6, equal to 10: 1: 10, the maximum values of the physicomechanical properties of concrete are achieved. In the case of an increase in C ₃ A, the effectiveness of the superplasticizer decreases, since the adsorption capacity of the aluminate phases significantly exceeds the adsorption capacity of the silicate phases. An increase in the content of С-3 leads to an increase in the adsorption layers on the solid phase or on its active centers, which complicates the subsequent coagulation of small and medium-sized particles to large blocks and screening of intermolecular attraction, which in turn leads to an increase in the setting time and a slowdown of the structure formation processes . A decrease or increase in the sealant "Aquatron-6" leads to a decrease in water resistance in the first case and a decrease in strength in the second.

 From the table. 2 it can be seen that the introduction of the Akvatron-6 sealant into the concrete mix contributes to an increase in early stripping strength, while the cost of materials and, consequently, the cost of manufacturing concrete of the proposed composition is low.

Claims (1)

Concrete mixture for the manufacture of high-quality concrete in the production of reinforced concrete products for underground tunneling and hydraulic structures, including M500 Portland cement, 5-10 mm and 10-20 mm granite crushed stone, sand, S-3 superplasticizer, mineral component and water as a binder characterized in that said Portland cement contains tricalcium aluminate-C ₃ A in an amount of 4-7 wt. % of the binder, river sand with a fineness modulus of 2-3 is used as sand, and Aquatron-6 sealant as a mineral component, the ratio of the content of tricalcium aluminate-C ₃ A in Portland cement to the content of C-3 and to the Aquatron sealant -6 "is determined by the formula C ₃ A: C-3:" Aquatron-6 "= 10: 1: 10 in the following ratio of components, wt. %:
Portland cement M500 - 17.97-18.23
Granite crushed stone of fraction 5-10 mm - 14.24-15.25
Granite crushed stone of a fraction of 10-20 mm - 29.79-31.00
Sand of the river - 28.69-30.49
Superplasticizer S-3 - 0.076-0.136
Sealant "Aquatron-6" - 0.76-1.36
Water - Else

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