High-strength, quick-hardening, self-compacting concrete mix

Abstract

FIELD: construction materials.SUBSTANCE: invention relates to the field of building materials, in particular to fine-grained self-sealing concrete mixtures, and can be used in the production of construction and installation work in winter. High-strength, quick-hardening concrete, consisting of a composite binder, quartz sand, microsilica, microcalcite, an accelerating additive and water, contains as a binder a composite binder consisting of Portland cement and aluminous cement, as sand - quartz sand of two fractions: 0.1–0.4 mm, 0.4–0.8 mm, as an active mineral additive - microsilica MK-85 with a bulk density of 152.2 kg / m3, as an inert mineral additive - microcalcite with the largest particle size (98%) of 100 μm, as a plasticizing additive - a plasticizer based on polycarboxylate esters with a densityρ =1.064 g / cm3 and pH=5.04, as an accelerator additive - anhydrous trisodium citrate with an aqueous solution pH = 8.3–8.5 and water in the following ratio of components, wt.%: Portland cement – 31.5; aluminous cement – 3.5; water – 8; microsilica – 5.2; microcalcite – 7; quartz sand grade 0.1–0.4 – 12.7; quartz sand grade 0.4–0.8 – 29.6; plasticizer – 0.7; sodium citrate 3 – substituted anhydrous – 1.8.EFFECT: increasing in the rate of concrete strength gain in the first hours of hardening, due to which the proposed composition can be used in winter concreting.1 cl, 1 tbl

Description

[0001] The invention relates to the field of building materials, in particular to fine-grained self-compacting concrete mixtures, and can be used in the production of construction and installation works in the winter period (the time of year with an expected average daily outdoor air temperature below +5°C and a minimum daily temperature below 0°C).

[0002] A fast-acting concrete mix for repairing building structures is known (RU 2522588). The composition of the mix contains, wt. %: general construction Portland cement CEM I 42.5 - 32.5…34.5; aluminous cement - 8.1…8.6; modified in shape fractionated and finished waste from mining enterprises - 41.0…42.4; plasticizing additive based on polycarboxylate esters - 0.20…0.25; active mineral additive microsilica - 4.0…4.5; polypropylene bicomponent fiber - 0.03…0.05; water - the rest. The disadvantage of this invention is the absence of hardening accelerator additives, which will not allow the use of the composition in winter concreting.

[0003] A concrete mix and an additive to the concrete mix are known (RU 98112279). The composition of the additive contains the following components, wt. %: pentaerythritol production waste based on sodium formate - 15 ... 17; Lignopan - technical lignosulfonates modified with electrolytes with a molecular weight of 10-50 kDa - 1. The concrete mix should have included at least one cement from the following group as a binder: Portland cement, pozzolanic cement, slag Portland cement, quick-hardening Portland cement, aluminous cement. The concrete mix also includes coarse and fine aggregate. The disadvantage of this solution is the use of Lignopan as a plasticizing additive, which will not allow obtaining a self-compacting concrete mix, as well as the use of sodium formate, which limits the temperature range of application of the invention to -15 ° C.

[0004] A self-compacting concrete mixture is known (RU 2775294). The self-compacting concrete mixture contains cement, sand, crushed stone, superplasticizer, active and inert mineral additives and water in the following ratio of components, wt. %: Portland cement CEM I 52.5N with a tricalcium aluminate content of no more than 5% - 7.9-15.7, condensed uncompacted microsilica - 1.96-1.97, mineral powder from carbonate rocks - 3.9-11.9, sand with a fineness modulus of 1.8 - 32.32-32.4, crushed stone of fraction 5-20 mm - 39.4-39.5, superplasticizer based on modified polycarboxylate esters Sika ViscoCrete 25 HE-C - 0.22, water - 6.11-6.5. The disadvantage of this technical solution is the lack of hardening accelerator additives, which made it possible to carry out concrete work at sub-zero air temperatures.

[0005] The closest technical solution to the stated one is high-strength concrete with accelerated strength gain in the first 7 days of hardening (RU 2562625). Accelerated strength gain is achieved through the use of a complex additive, which contains, wt. %: polycarboxylate polymer based on methacrylic acid with a density of ρ = 0.95 g / cm 3 and pH=7±0.5 - 9.0-10.5; polycarboxylate polymer based on allyl ester and maleic acid anhydrite with a density of ρ=1.03 g / cm 3 and pH=7±0.5 - 10.5-11.0; sodium gluconate C6H 11 NaO7 - 2.5-2.9; sodium formate, HCOONa - 1.3-1.4; water - 75.2-75.7. High-strength concrete also contains a binder, crushed stone, sand, a silica-containing component, and water. A disadvantage of this solution is the use of sodium formate as a hardening accelerator, the maximum application temperature of which is no more than -15°C, and the acceleration of concrete hardening by only the seventh day of curing.

[0006] The technical result of the invention is an increase in the rate of concrete strength gain in the first hours of hardening, due to which the proposed composition can be used in winter concreting.

[0007] The technical result is achieved by the fact that a composition of high-strength, quick-hardening, self-compacting concrete is proposed, consisting of a binder, quartz sand, microsilica, microcalcite, plasticizer, accelerating additive and water, while using

[0008] as a binder - a composite binder consisting of Portland cement and aluminous cement,

[0009] as sand - quartz sand of two fractions: 0.1-0.4 mm, 0.4-0.8 mm,

[0010] as an active mineral additive - microsilica MK-85 with a bulk density of 152.2 kg / m3 3 ,

[0011] as an inert mineral additive - microcalcite with the largest particle size (98%) of 100 μm,

[0012] as a plasticizer - a plasticizer based on polycarboxylate esters with a density of ρ=1.064 g / cm 3 and pH=5.04,

[0013] as an accelerating additive - anhydrous trisodium citrate with an aqueous solution pH of 8.3-8.5 with the following ratio of components, wt. %:

[0014] Portland cement 31,5 aluminous cement 3,5 water 8 microsilica 5,2 microcalcite 7 quartz sand fraction 0.1-0.4 12,7 quartz sand fraction 0.4-0.8 29,6 plasticizer 0,7 accelerating additive 1,8

[0015] High-strength, quick-hardening, self-compacting concrete mix is ​​produced by pre-mixing high-alumina cement and Portland cement, followed by the addition of microsilica, microcalcite, and quartz sand, and mixing until smooth. Mixing water containing pre-dissolved additives is then added to the resulting dry mix.

[0016] To test the strength of concrete produced from the declared high-strength, quick-hardening, self-compacting concrete mix, 70×70×70 mm cube specimens were prepared. The metal mold was pre-cooled at the holding temperature, then filled with concrete mix at room temperature (23°C), after which the molds containing the mix were placed in a climatic chamber for the specified time. After the specified time, the specimens were stripped, thawed to a surface temperature of 5°C, and tested using a hydraulic press in accordance with GOST 10180-2012. The compressive strength results for the concrete specimens are presented in Table 1.

[0017]

[0018] The results obtained confirm the achievement of the declared technical result.

Claims

High-strength self-compacting quick-hardening concrete consisting of a binder, quartz sand, microsilica, microcalcite, plasticizer, accelerating additive and water, characterized in that it contains as a binder - a composite binder consisting of Portland cement and aluminous cement, as sand - quartz sand of two fractions: 0.1-0.4 mm, 0.4-0.8 mm, as an active mineral additive - microsilica MK-85 with a bulk density of 152.2 kg / m3 3 , as an inert mineral additive - microcalcite with the largest particle size (98%) of 100 µm, as a plasticizer - a plasticizer based on polycarboxylate esters with a density of ρ = 1.064 g / cm 3 and pH=5.04, as an accelerating additive - anhydrous trisodium citrate with an aqueous solution pH of 8.3-8.5 with the following ratio of components, wt. %: Portland cement 31,5 aluminous cement 3,5 water 8 microsilica 5,2 microcalcite 7 quartz sand fraction 0.1-0.4 12,7 quartz sand fraction 0.4-0.8 29,6 plasticizer 0,7 accelerating additive 1,8

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