RU2435746C2 - Concrete mixture - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to low-cement concrete mixtures and can be used in industrial, civil, ameliorative and transport construction, primarily in factory technology of reinforced concrete prefabricated structures. The concrete mixture contains portland cement, polycarboxylate ether-based superplasticiser, microsilica containing not less than 75-80% amorphous- glass-like silica, average or coarse quartz or feldspar sand with particle size of up to 5 mm, crushed rock with crushing capacity 800-1400 and water. The mixture additionally contains ground quartz sand or ground rock flour from dense rocks with specific surface area (3-5)103 cm2/g and very fine quartz sand with particle size of 0.1-0.63 mm, with the following content of components in kg per m3 of the concrete mixture: portland cement of a grade not lower than M500 150-300, 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 400-500, crushed rock 800-850, ground quartz sand or rock flour 150-290, very fine quartz sand 40-500, water 140-170. ^ EFFECT: low specific consumption of cement per unit strength of the concrete. ^ 2 tbl

Description

The invention relates to concrete mixtures for producing concrete with low specific cement consumption per unit of strength (ratio of cement consumption in kilograms to concrete strength under compression in megapascals), not exceeding 4.5 kg / MPa, and can be used in industrial civil, reclamation , transport construction, mainly in the technology of prefabricated reinforced concrete structures. 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 coarse aggregate of 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 , silica 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 a concrete mixture containing per 1 m ^{3 of} Portland cement - 330 kg, quartz sand - 800 kg / m ³ , granite crushed stone - 850 kg, MB modifier - 80 kg, mineral powder (limestone flour) - 150 kg, water - 150 kg [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, p.15. Compositions No. 6, section 13 (A1)].

The disadvantage of this concrete mixture is the increased specific consumption of cement per unit of strength, amounting to 4.85 kg / MPa.

The required technical result is to reduce cement consumption per unit of strength (not more than 4.5 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 800-1400 and water additionally contains increased amounts of ground quartz sand or ground stone flour dense rocks with a specific surface area (3-5) x 10 ³ cm ² / g, a very fine quartz sand at one granulometry fractions 0,1-0,63 mm, with the following component ratio, kg / m ³ concrete:

- Portland cement grade not lower than M500 150-300 - carboxylate-based superplasticizer ether,% by weight of cement, calculated on the dry matter 0.5-1.5 - silica fume,% by weight of cement 10-15 - medium or large quartz or feldspar sand 400-550 - crushed stone from dense rocks 800-850 - ground quartz sand or stone flour 150-290 - very fine quartz sand 400-600 - water 140-170

The concrete mixture is characterized in that the specific consumption of cement per unit of strength of concrete made on its basis does not exceed 4.5 kg / MPa. This is achieved, in particular, by the fact that the introduction of an increased amount of stone flour or ground quartz sand (with a specific surface area of (3-5) · 10 ³ cm ² / g) close to or somewhat higher than the cement consumption, as well as the addition of a significant amount very fine quartz sand fractions from 0.1 to 0.63 mm, forms a specific rheological flow matrix in the aqueous medium together with cement and silica fume and provides a strong thinning 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 rocks - diabase, andesite, granite, etc. react with hydrolysis lime to form calcium hydrosilicates, complementing the positive effect of nanosized particles of silica fume (in the formation of hydrosilicates and increasing strength) . Basalt rheolite glasses are also involved in strength formation.

For the manufacture of low-cement concrete mixture using the following materials.

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

Super softener Melflux F 1641; Melflux F 2641.

Silica fume with an amorphous (vitreous) silica content of 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 of 800-1400 crushability.

Ground quartz sand and ground rocks 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 of M _cr = 2.2.

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

Average feldspar sand with a particle size of up to 5 mm with a particle size modulus of M _cr = 2.1.

Granite crushed stone fractions of 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 low-cement raw material mixture according to the invention has a lower specific cement consumption per unit of concrete strength, not exceeding 4.5 kg / MPa, and is not inferior in strength to concrete according to the closest and other analogues.

Table 1 The consumption of concrete mixture materials, kg / m ³ concrete Name of materials Concrete mixes one 2 3 four 5 6 7 8 9 10 eleven 12 Prototype Portland cement M500 150 180 236 300 150 182 240 296 155 183 242 298 330 Super softener Melflux F 1641 0.9 1.4 - - 1,2 - - 1,5 - 1,5 - 1,5 Joint venture S-3 + Super softener Melflux F 2641 - - 1.4 1,2 - 1,2 2.1 - 1,1 - 1,1 - + silica fume (85) Silica fume 22 eighteen 24 thirty twenty twenty 28 44 23 23 31 42 Ground stone flour S _beats = 3500 cm ² / g - - - - - ground basalt - - - - 181 - - - - 190 - - - from ground diabase - - - - - 195 - - - - - - - ground andesite - - - - - - 245 - - - 276 - - ground granite - - - - - - - 268 - - - 273 - ground limestone - - - - - - - - 178 - - - 150 Ground quartz sand S _beats = 3500 cm ² / t 158 170 217 270 - - - - - - - - - Very fine quartz sand fr. 0.1-0.63 mm 550 532 485 450 545 540 482 445 540 535 478 430 - Medium Quartz Sand - - - - 545 - - - - - - - - Coarse quartz sand - - - - - 545 460 - - - 465 - 800 Middle feldspar sand 550 532 480 450 - - - 460 535 538 - 455 - Granite crushed stone 830 850 840 800 825 840 845 810 835 845 850 805 850 Water 167 162 146 160 168 165 140 158 164 165 143 156 150 The stiffness of the mixture, seconds 62 thirty - - 52 27 9 - 70 24 - - - Cone draft, cm - - 8 12 - - - 10 - - 7 eleven 28

table 2 The name of indicators Numbers of concrete mixes one 2 3 four 5 6 7 8 9 10 eleven 12 Prototype Cement consumption, kg 150 180 236 300 150 182 240 296 155 183 242 298 330 Compressive strength, MPa 34 43 64 74 35 45 65 73 35 44 62 70 68 Specific cement consumption per unit of strength, kg / MPa 4.41 4.19 3.69 4.05 4.28 4.04 3.69 4.05 4.43 4.16 3.9 4.14 4.85

Thus, the proposed concrete mixture is characterized by a reduced cement consumption per unit of strength, not exceeding 4.5 kg / MPa, which proves the achievement of the required technical result.

Claims (1)

Concrete mixture including Portland cement, a polycarboxylate ether-based superplasticizer, silica fume with amorphous - vitreous silica content of at least 75-80%, medium or coarse quartz or feldspar sand with a grain size of up to 5 mm, crushed stone from rocks with a crushing grade of 800-1400 and water, characterized in that it 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 when next containing uu components kg per 1 m ³ of concrete mixture:
Portland cement grade not lower than M500 150-300 polycarboxylate-based superplasticizer ether,% by weight of cement in terms of dry substance 0.5-1.5 silica fume,% by weight of cement 10-15 medium or large quartz or feldspar sand 400-550 solid rock crushed stone 800-850 ground quartz sand or stone flour 150-290 very fine quartz sand 400-550 water 140-170