RU2559235C1 - Method of concrete mixture preparation - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: in the method of concrete mixture preparation 50% of the calculated amount of cement is previously mixed with gauged water and additives of superplasticisers of different chemical base: polycarboxylate ether - REMICRETE SP60 and condensation product based on sodium salt of naphthalenesulfonic acid and formaldehyde - RELAMIKS T2 in the ratio 1:1 and subjected to mechanochemical activation in rotary pulsation apparatus with speed of rotation of working body of 5000 rev/min during 2-3 min, followed by mixing the remaining portion of cement, coarse and fine filler in the concrete mixer for at least 5 minutes.

EFFECT: increase of growth rate of the concrete strength, especially in the early stages of hardening while maintaining their high final strength, increased mobility of concrete mixture, increased frost and water resistances.

2 cl, 1 tbl

Description

The invention relates to the field of construction, in particular to a technology for the preparation of concrete mixtures used for the manufacture of concrete and reinforced concrete products and structures in monolithic and prefabricated construction.

A known method of preparing a concrete mixture, including mixing part of the estimated dose of mixing liquid with cement in the mixer-activator, introducing the remaining part of the calculated dose of mixing liquid into the concrete mixer with aggregate, subsequent introduction of the suspension obtained in the mixer-activator into the concrete mixer and finally mixing the resulting mixture, characterized in that water is used as mixing liquid, which is preliminarily poured into the activator mixer in the amount of (40-70)% of the calculated (recipe d) mixing a dose of liquid, which during pouring of the mixer-activated activator (RU A 2496748, publ. 10.27.2013).

The disadvantage of this invention is the low strength of the resulting concrete, as well as the technical complexity of the process of preparing the concrete mixture.

A known method of preparing a concrete mixture, comprising mixing a binder, aggregates, mixing water, in which glycerol is previously dissolved in an amount of 0.05-0.3% by weight of cement, mechanical activation is performed at the end of stage 1 of the structure formation process. The mixture of sand and cement is closed with a part of the calculated amount of water for mixing with the estimated amount of glycerol, and the rest of the water, which contains the hardening accelerator, together with the coarse aggregate, is introduced into the concrete mixture after preliminary mixing for 1.5-2.5 minutes ( RU 2097364 A, publ. 11/27/1997).

The disadvantages of this invention are the lengthy process of preparing the concrete mixture, as well as the low strength of the resulting concrete.

A prototype of the present invention is a method for producing a concrete mixture, comprising preactivating a portion of the cement from its calculated amount with superplasticizer and then mixing it with the remainder of the cement, aggregate and water. Activation is carried out by stirring in an aqueous medium at W / C = 0.5-1.0 for 40-45 minutes, while part of the cement is 10% of the calculated amount (RU 2371412 C1, publ. 27.10.2009).

The disadvantage of this invention is the high energy intensity and duration of the process of preparing the concrete mixture, as well as the low strength of the resulting concrete.

The objective of the present invention is to increase the growth rate of concrete strength in the early stages of hardening, especially in the first day, while maintaining their high grade strength, increasing frost resistance and water resistance.

The result is achieved in that in a method for preparing a concrete mixture, including preliminary activation of a portion of the calculated amount of cement with mixing water containing superplasticizers and subsequent mixing with the rest of the cement and aggregates, according to the invention, the mechanochemical activation is carried out by mixing in a rotary-pulsating apparatus with a number of working revolutions body 5000 rpm for 2-3 minutes, part of the cement is 50% of the calculated amount, using superplasticizers t additives based on polycarboxylate ether - REMICRETE SP60 and condensation product based on the sodium salt of naphthalenesulfonic acid and formaldehyde - RELAMIKS T2 in the ratio 1: 1.

The result is also achieved by the fact that the consumption of additives taken in the specified ratio is 1% by weight of cement.

RELAMIX T2 additives, a condensation product based on the sodium salt of naphthalene sulfonic acid and formaldehyde (hereinafter RELAMIX T2 additive) according to TU 5870-002-14153664-04 with change No. 1, REMICRETE SP60 - based on polycarboxylate ether - certified, were used as superplasticizers the additive to concrete from the group of plasticizers (FM) has the certification number: 0764-CPD-0012 (according to EN 934-2: 2001).

A method of preparing a concrete mixture is as follows.

For the preparation of the concrete mix of the production composition, M400 PC D20 cement of the Ulyanovsk plant was used, which meets the requirements of GOST 31108-2003, sand of the Kama-Ustinsky field, which meets the requirements of GOST 8736-93 and GOST 8735-88, and crushed stone of the Kamsko-Ustyinsky field, which meets the requirements of GOST for concrete , with the following ratio (parts by weight):

Cement: sand: crushed stone = 1: 1.13: 2.68.

Consumption of cement per 1 m ^{3 of} concrete amounted to 490 kg.

Mechanochemical activation was carried out in a rotary pulsation apparatus RPA 0.8-55A-2.2UZ according to TU 5132-001-70447062.

Preliminarily, 50% of the calculated amount of cement was mixed with mixing water, where the indicated additives of superplasticizers were previously dissolved, and subjected to mechanochemical activation (MHA) in a rotary pulsation apparatus with a working body speed of 5000 rpm for 2-3 minutes, followed by mixing of the remaining parts of cement, coarse and fine aggregate in the concrete mixer for at least 5 minutes.

The dosage of Relamix T2 additive was 0.5% by weight of cement, the dosage of REMICRETE SP60 additive was 0.5% by weight of cement.

Samples — cubes with sizes of 10 × 10 × 10 — were made from concrete mixtures. After 1.3, 28 days of normal hardening, the samples were subjected to mechanical tests. The strength of the samples was determined in accordance with GOST 18105-86. Frost resistance of the samples was determined in accordance with GOST 10060.3-95, water resistance in accordance with GOST 12730.5-84, the mobility of the concrete mixture was determined in accordance with GOST 10181.1-81.

The results of physical and mechanical tests of the samples are shown in table 1.

Based on the data obtained, it is seen that concrete obtained on the basis of mechanochemically activated cement slurry with the addition of superplasticizers of various chemical bases has a compressive strength of 2.86 times greater in daily age than concrete obtained by the prototype. At three days and 28 days, the concrete obtained by this method has a compressive strength of 1.84 and 1.43 times higher than the strength of concrete obtained by the prototype.

Frost resistance of concrete F500 and water resistance W12. The draft of the cone when determining the mobility of the concrete mixture was 12 cm.

Claims (2)

 1. A method of preparing a concrete mixture, including the preliminary activation of a portion of the estimated amount of cement with mixing water containing superplasticizers and subsequent mixing with the rest of the cement and aggregates in the concrete mixer for at least 5 minutes, characterized in that the mechanochemical activation is carried out by mixing in an aqueous medium in a rotary pulsation apparatus with a working body speed of 5000 rpm for 2-3 minutes, part of the cement is 50% of the calculated amount, as a soup plasticizers use additives based on polycarboxylate ether - REMICRETE SP60, the condensation product based on the sodium salt of naphthalenesulfonic acid and formaldehyde -RELAMIKS T2 in the ratio 1: 1. 2. The method according to p. 1, characterized in that the consumption of additives taken in the specified ratio is 1% by weight of cement.