RU2439020C2 - Concrete mixture - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to composition of a concrete mixture for producing high-strength concrete and can be used in industrial-civil, ameliorative construction and when building unique high-load structures - bridges, television relay towers, oil and gas platforms, piers and berths. The concrete mixture contains portland cement, polycarboxylate ether-based superplasticiser, microsilica, average or coarse quartz or feldspar sand, dense rock chips with crushing capacity grade 1200-2000, very fine quartz sand with particle size 0.1-0.63 mm and ground quartz sand or dense rock flour with specific surface area (3-5)·10³ cm²/g and water, with the following ratio of components in kg/m³ of the concrete mixture: portland cement of a grade not lower than M500 330-480, polycarboxylate ether-based superplasticiser as a percentage of the weight of the cement in terms of dry substance 0.5-1.5, microsilica as a percentage of the weight of the cement 10-15, average or coarse quartz or feldspar sand 300-600, dense rock chips 800-900, ground quartz sand or rock flour 200-350, fine quartz sand with particle size 0.1-0.63 mm 400-600, water 140-180.

EFFECT: low specific consumption of cement per unit strength of the concrete.

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Description

The invention relates to concrete mixtures for producing concrete with low specific cement consumption per unit of strength (the ratio of cement consumption in kilograms to concrete strength under compression in megapascals), and can be used in civil engineering, land reclamation, transport construction, mainly in prefabricated construction technology from reinforced concrete. It can be implemented in the monolithic construction of residential, public and administrative buildings.

Known concrete mixtures with normalized cement consumption for medium grades M300-500, including binder, coarse and fine aggregate and water, containing “400” or “500” grades as Portland cement, quartz or feldspar sands up to 5 mm in size as fine aggregate , as a large aggregate, crushed stone from rocks or gravel fractions from 5 to 20 mm [All-Union norms for technological design of precast concrete enterprises (ONTP-7-85). Moscow, 1986, p.26, table 2, p.6].

The disadvantage of these concrete mixtures is that the concretes made of them of medium grades M300-M500 contain increased cement consumption from 270 to 500 kg per 1 m ³ . For concrete grades M300 (30 MPa), M400 (40 MPa), M500 (50 MPa), the normalized cement costs for bench and aggregate-flow technologies, respectively, are 370, 400 and 500 kg / m ³ . For this reason, in these concrete mixtures, the specific consumption of cement per unit of strength is relatively large, respectively 12.3 kg / MPa, 10 kg / MPa and 10 kg / MPa.

Also known are concrete mixtures for high-grade concrete with a maximum strength of 58-73 MPa with Portland cement costs M500 330-380 kg / m ³ , quartz sand - 820-880 kg / m ³ , granite crushed stone - 920-950 kg / m ³ , water - 150-170 kg and a modifying additive - 40-75 kg / m ³ , which is used as a modifier MB, consisting of superplasticizer, silica fume and setting agent [Kaprielov S.S., Travush V.I., Karpenko N.I. ., Sheinfeld A.V., Kiseleva Yu.A., Prigozhenko O.V. Modified concretes of a new generation in the structures of the Moscow City Business Center. Part 1 // Building materials. No. 10, M., 2006. p.13-16. Table 2, C.15. Compositions No. 1 to 5, composition No. 6 - Tower A, composition No. 7). The specific cement consumption in these concrete mixtures is from 4.52 to 6.55 kg / MPa.

The disadvantage of these concrete mixtures is also the relatively large specific consumption of cement per unit of strength.

In addition, a concrete mixture is known [RU 2357940, С04В 28/04, С04В 18/04, С04В 24/00, С04В 111/20, 06/10/2009] containing Portland cement, sand fraction 0.315-2 mm, gravel fraction 5-20 mm, silica fume, superplasticizer C-3, finely ground quartz sand, mixing water, an organosilicon mixture — a mixture of methyl phenylcyclosiloxanes and soot white, and mixing water additionally contains PVA polyvinyl alcohol and tar resin — a product of processing coal by pyrolysis method, in the following ratio of components, oil, pyrolysis method, .%:

Portland cement 18.0-20.0 silica fume 1.0-2.0 crushed stone fractions 5-20 mm 39.98-40.68 sand fraction 0.315-2 mm 28.0-32.0 white soot 0.9-1.0 superplasticizer C-3 0.15-0.25 fine quartz sand 0.8-1.0 organosilicon additive - mixture of methylphenylcyclosiloxanes 0.02 polyvinyl alcohol 0.07-0.15 tar water 0.4-0.6 water 6.0-7.0

The disadvantage of this concrete mixture is also the relatively large specific consumption of cement per unit of strength.

Closest to the proposed one is concrete mix for high-grade concrete with a strength of 106 MPa, containing 485-495 kg per 1 m ^{3 of} Portland cement concrete, 725-740 kg of quartz sand, 975-990 kg of crushed granite, and MB 30C modifier 108 -110 kg, silicone emulsion CE 30-40 - 0.4 kg, water - 140-141 kg [S. S. Kaprielov, Travush V.I., Karpenko N.I., Sheinfeld A.V., Kardumyan G. S., Kiseleva Yu.A., Prigozhenko O.V. "Modified high-strength concrete of classes B80 and B90 in monolithic structures." Part 2 // Building materials. No. 3, M., 2008. S.9-13. The composition of B90 P5, p.11].

The disadvantage of this concrete mixture is the increased specific consumption of cement per unit of strength, amounting to more than 4.57 kg / MPa.

The required technical result is to reduce cement consumption per unit of strength (not more than 4.2 kg / MPa).

The required technical result is achieved in that a concrete mixture including Portland cement, a polycarboxylate ether-based superplasticizer, silica fume with an amorphous (glassy) silica content of at least 75-80%, medium or large quartz or feldspar sand, crushed stone from rocks with a crushability grade M1200-M2000 and water, additionally contains ground quartz sand or ground stone flour from dense rocks with a specific surface area of (3-5) · 10 ³ cm ² / g and very fine quartz sand fraction 0.1-0.63 mm in the wake containing component content, kg per 1 m ^{3 of} concrete mixture:

Portland cement grade not lower than M500 330-480 carboxylate-based superplasticizer ether, in% by weight of cement on dry matter 0.5-1.5 silica fume, in% by weight of cement 10-15 medium or large quartz or feldspar sand 300-600 solid rock crushed stone 800-900 ground quartz sand or stone flour 200-350 very fine quartz sand fraction 0.1-0.63 mm 400-600 water 140-180

The introduction of an increased amount of dispersed stone flour or ground quartz (with a specific surface area of (3-5) · 10 ³ cm ² / g) close to cement consumption, as well as the addition of a significant amount of very fine quartz sand fraction from 0.1 to 0.63 mm forms in the aqueous medium together with cement and silica fume a specific rheological flow matrix and provides a strong liquefaction of the fine-grained mixture under the action of superplasticizer. This allows you to additionally fill the fluid mixture with ordinary sand and gravel and significantly reduce the specific consumption of water and cement.

The finest nanosized particles of quartz from ground quartz sand or stone flour from ground silica-containing rocks - diabase, andesite, etc. - react with hydrolysis lime to form hydrosilicates, calcium hydroaluminates, complementing the positive effect of nanosized particles of silica fume (in the formation of hydrosilicates concrete). Basalt rheolite glasses are also involved in strength formation.

The following materials are used for the manufacture of low-cement concrete mix:

Portland cement ПЦ500Д0 according to GOST 10178-85 and GOST 30515-97;

Super softener Melflux F 1641; Melflux F 2641;

Silica fume with a content of amorphous (vitreous) silica 79%;

Ground stone flour with a specific surface of 3100-3500 cm ² / g from dense rocks with a true density: basalt with ρ _and = 3.05 g / cm ³ , diabase with ρ _and = 3.0 g / cm ³ , andesite with ρ _and = 2.8 g / cm ³ , granite with ρ _and = 2.71 g / cm ³ , limestone with ρ _and = 2.72 g / cm ³ with a grade for crushing ability from 1000 to 1400;

Ground quartz sand with a specific surface area of 3500 cm ² / g;

Very fine quartz sand fraction 0.1-0.63 mm;

Average quartz sand with a particle size of up to 5 mm with a particle size modulus M _cr = 2.2;

Coarse quartz sand with a particle size of up to 5 mm with a particle size modulus M _cr = 2.7;

Coarse feldspar sand with a particle size of up to 5 mm with a particle size modulus M _cr = 2.2;

Crushed stone diabase fractions 5-10 mm.

The concrete mixture is prepared in a forced-action concrete mixer.

Testing the concrete mixture is carried out according to GOST 10181-2000.

The compressive strength of concrete is determined according to GOST 10180-90.

The composition of the concrete mixture and workability indicators are shown in table 1.

Cement consumption per 1 m ^{3 of} concrete mixtures, compressive strength of concrete and specific cement consumption per unit of concrete strength are given in table 2.

The above research results indicate that the raw material mixture according to the invention has a lower specific cement consumption per unit of concrete strength, not exceeding 4.2 kg / MPa, and is not inferior in strength to concrete according to the closest and other analogues.

Thus, the proposed concrete mixture is characterized by a reduced cement consumption per unit of strength, not exceeding 4.2 kg / MPa, which proves the achievement of the required technical result.

Claims (1)

Concrete mixture including Portland cement of a grade of at least 500, a superplasticizer based on polycarboxylate ether, silica fume with an amorphous vitreous silica content of at least 75-80%, medium or large quartz or feldspar sand, crushed stone from rocks with a crushing grade M1200-M2000 and water , characterized in that it further contains ground quartz sand or ground stone flour from dense rocks with a specific surface area of (3-5) · 10 ³ cm ² / g and fine quartz sand fraction 0.1-0.63 mm in the following composition ntov, kg per 1 m ^{3 of} concrete mix:
Portland cement grade not lower than M500 330-480 carboxylate-based superplasticizer ether, in% by weight of cement on dry matter 0.5-1.5 silica fume, in% by weight of cement 10-15 medium or large quartz or feldspar sand 300-600 solid rock crushed stone 800-900 ground quartz sand or stone flour 200-350 fine quartz sand fraction 0.1-0.63 mm 400-600 water 140-180