RU2107048C1 - Method of preparing concrete mix - Google Patents

Abstract

FIELD: manufacture of building materials. SUBSTANCE: in manufacture of reinforced concrete parts from dry and low-mobility concrete mixes using iron frameworks, concrete mixes are supplemented by 0.8-2.5 wt % (calculated for solid materials) of compound additive. Additive is made up of plasticizer (glycol and Cellosolve production waste) based on crude polyglycols, hardening activator (sulfate-containing alkali metal salts), and framework corrosion inhibitor (sodium nitrate). EFFECT: improved reinforced concrete characteristics. 4 cl, 5 tbl

Description

 The invention relates to compositions of concrete mixtures with additives and can be used in the production of reinforced concrete products made from rigid and inactive concrete mixtures.

 A known method of preparing a concrete mixture, which consists in mixing cement, aggregate, mixing water and 0.1 to 0.5% of the additive by weight of cement previously prepared by mixing animal glue, lime and water, and animal - casein glue, lime and water are mixed in a ratio of 1: 0.1: 1 and subjected to heat treatment in an autoclave at a pressure of 1.8 - 2.2 bar for 2-3 hours [1].

 The disadvantages of the method are the complexity of the process of preparing a complex additive, the additional consumption of thermal energy and, as a result, the cost of the final products.

The closest in technological essence is a method of preparing a concrete mixture by mixing cement, aggregate, mixing water and 0.5 - 1.5% by weight of cement of a complex additive, including soap liquor and waste products from the production of synthetic detergents, and the complex additive additionally contains sodium polyphosphate and as a waste of the production of synthetic detergents - a waste of the production of washing powders based on alkylbenzenesulfonates in the following ratio of the components of the complex Ki, wt.%:
Sub-soap liquor - 99.58-99.70
Waste from the production of washing powders based on alkylbenzenesulfonates - 0.05-0.07
Sodium polyphosphate - 0.25-0.35 [2].

 The disadvantage of the invention is the complex composition of the additive, as well as the fact that the heat and moisture treatment of products from concrete mix is carried out at elevated temperature for a long time, which gives additional costs of thermal energy.

 The objective of the invention is to save heat and electricity in the production of concrete products.

 The technical result is the most complete involvement of cement in the process of formation of a concrete product due to the proposed complex additives and, as a consequence, the exclusion of the process of heat and moisture treatment of manufactured structures.

The technical result is achieved by the fact that in the method of preparing the concrete mixture by mixing cement, aggregate, water and a complex additive including a plasticizer and a hardening activator, the waste products for the production of glycols and celluloses based on crude polyglycols are used as a plasticizer, and sulfate-containing ones as a hardening activator salts of alkali metals and additionally introduce a corrosion inhibitor of reinforcement in the following ratio of components of the complex additives, wt.%:
plasticizer - 4.3 - 6.5
hardening activator - 84 - 95
corrosion inhibitor - 1.9 - 2.8
A complex additive is added in an amount of 0.8 - 2.5% by weight of cement (in terms of dry matter).

As a plasticizer in a complex additive, products containing a mixture of ethers based on ethylene glycol of the general formula are used.
OH (CH ₂ CH ₂ ) nH,
Where
n = 2 - 7 with a density of 0.96 - 1.2 kg / dm ³ .

In the method of preparing the concrete mixture, sulfate-containing salts of the Na ₂ SO ₄ group are used; K ₂ SO ₄ ; Na ₂ SO ₄ • 2H ₂ O; Na ₂ SO ₄ • 10H ₂ O or mixtures thereof. In the method of preparing the concrete mixture in a complex additive, NaNO _{2 is} used as a corrosion inhibitor of the reinforcement.

 Compared with the prototype, the use as a complex additive to concrete mixtures of a mixture of waste products from the production of glycols and celluloses based on crude polyglycols with various alkali metal salts in the claimed amounts is new.

Using the proposed complex additives for concrete mixtures allows plasticizing the concrete mixture while reducing the amount of mixing water by 10-15%; accelerate the hardening of concrete by 2-3 times, while the strength of hardened concrete increases by 25-35%, frost resistance by 2 times, water resistance by 2 steps; upon receipt of equal strength concrete, cement savings of 12-14% are achieved; when using cements of grades 500-600, it is possible to obtain high-strength concrete of grades 700-900; it is also possible to reduce the cost of thermal energy by 5-10 times during heat and moisture treatment due to the hardening process of concrete at temperatures above plus 10 ^o C.

 The additive does not cause corrosion of steel reinforcement in concrete and can be used in structures with conventional and prestressed reinforcement.

 For the preparation of concrete mixtures, cement, sand and gravel are used as starting materials.

Example. Use cement grade PC-M-400, the activity of which after steaming is 24.8 kg / cm ² , group 11 for the efficiency of steaming;
crushed stone ⌀ 3-20, γ _r - 1460 kg / m ³ , with a content of clay and dust particles of 2.5%. Strength grade Dr-16, and the content of needle and plate particles is 24.8%, the sand content is 8%;
Mkr sand - 2.5 with a bulk density of γ 1,450 kg / m ³ , with a gravel content of 12% in the sand.

 As a complex additive, a mixture of substances is used, the composition of which as a plasticizing component is crude polyglycols, which are wastes from the production of glycols and cellosolves that meet the requirements of TU 6-01-1352-88 developed by GOSNIIKhlorproekt.

Technical characteristics of crude polyglycols:
Appearance - a viscous liquid of dark color with a faint odor.

Density at 2 ^o C - 0.96-1.20
Boiling point - 150 ^o C
The crystallization temperature of an aqueous solution of 60 wt.% - -30 ^o C
Water Compatibility - Full
Flash point - 170 ^o C
Auto-ignition temperature - 350 ^o C
The complex additive contains Na ₂ CO ₄ salt and NaNO ₂ salt, which plays the role of a corrosion inhibitor, as a hardening activator. In addition, according to the results obtained, NaNO ₂ also accelerates the hardening of concrete, helping the plasticizing additive to involve cement in the hardening process.

 The source data for the preparation of concrete mixtures in the claimed ratios are given in table. 1-3.

The complex additive is used as an aqueous solution with a density of 1.045 - 1.15 g / cm ³ at 20 ^o C and pH ≈ 10.

 The preparation of a complex additive (the dissolution of the constituent components in water) is carried out immediately before the preparation of the concrete mixture and it is fed into a concrete mixer with mixing water. The amount of water included in the complex additive is subtracted from the total amount of mixing water.

 Below, as an example, the results of testing concrete samples made with the use of complex additives are given (see table. 4).

 All batches were carried out on inert aggregates of the Shepelevsky quarry, PC M-400 of the Voskresensky cement plant, activity after steaming was 26.8 MPa, the normative density of the cement test was 26.5%, test batches were carried out at a dosage for concrete M-200, sediment cone - 1 - 4 cm

Hardening temperature T = 16 - 20 ^o C.

Using a complex additive, cubes-samples of concrete М 300, 200, 100 with different mobility were made, hardening occurred at T (+10 ^o C), (+20 ^o C), cubes were tested at 24 hours after manufacture, after 48 hours and 7 days

 As a result of testing the cubes of samples for strength, the results are shown in table. 5.

 Note to table 5: the complex additive is 1.65% by weight of cement (in terms of dry matter).

From the data table. 5 it is seen that with less mobility and a hardening temperature of 20 ^o C, the strength increases by 16-20%, after 48 hours, the tempering strength is always obtained.

 The proposed method of preparing a concrete mixture using the proposed complex additives does not require additional processing equipment and can be used at all existing plants. The composition of the complex additives and its method of preparation are simple and original.

Claims (4)

1. A method of preparing a concrete mixture by mixing cement, aggregate, water and a complex additive comprising a plasticizer and a hardening activator, characterized in that the waste products for the production of glycols and cellosolves based on crude polyglycols are used as a plasticizer, and alkali sulfate salts are used as a hardening activator metals and additionally enter a corrosion inhibitor of reinforcement in the following ratio of the components of the complex additive, wt.%:
Softener - 4.3 - 6.5
Hardening activator - 84 - 95
Corrosion Inhibitor - 1.9 - 2.8
moreover, the specified additive is introduced in an amount of 0.8 - 2.5% by weight of cement / in terms of dry matter /. 2. The method of preparing the concrete mixture according to claim 1, characterized in that products containing a mixture of ethers based on ethylene glycol of the general formula OH / OCH ₂ CH ₂ / _n H, where N = 2 - 7 with a density of 0.96 - 1.2 kg / dm ³ . 3. The method of preparing the concrete mixture according to claim 1, characterized in that as the hardening activator use sulfate-containing alkali metal salts selected from the group of Na ₂ SO ₄ ; K ₂ SO ₄ ; Na ₂ SO ₄ • 2H ₂ O; Na ₂ SO ₄ • 10H ₂ O or mixtures thereof. 4. A method of preparing a concrete mixture according to claim 1, characterized in that NaNO _{2 is} used as a corrosion inhibitor.

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