RU2282601C2 - Concrete mixture - Google Patents

Abstract

FIELD: industry of building materials.

SUBSTANCE: invention relates, in particular, to preparing monolith concrete or ferroconcrete used in civil and industrial building. The concrete mixture comprising sand and crushed stone as a filling agent, a plasticizing agent, cement and water involves additionally the technological additive representing product of interaction of triethanolamine and higher unsaturated fatty acids or their mixtures with saturated fatty acids wherein the content of unsaturated fatty acids is 80%, not less, in the mole ratio of triethanolamine to higher unsaturated fatty acids from 1:0.8 to 1:1.35 in the following composition of the concrete mixture, kg/m³, cement, 350-362; sand, 735-770; crushed stone, 1072-1120; water, 168-181; plasticizing agent, 0.35-0.60, and indicated additive, 0.0006-0.008% of cement mass. Invention provides enhancing degree of concrete density and durability of concrete constructions, effectiveness of foam quenching and acceleration of concrete hardening for the first days.

EFFECT: improved and valuable properties of concrete mixture.

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Description

The invention relates to the production of building materials, in particular, to obtain monolithic concrete or reinforced concrete used in civil and industrial construction.

Known concrete mixtures containing Portland cement, sand, gravel, water, S-3 superplasticizer and mineral additives (Russian Patent No. 2223242), S-3 superplasticizer mixed with dextrin (RF patent application No. 20022100515), S-3 superplasticizer mixed with hydrophobizing liquid GKZH (Russian Patent No. 2203241), superplasticizer C-3 mixed with organosilicon liquid in an amount of 0.009-0.8 wt.%. (RF patent application No. 92006790). The closest in technical essence and the achieved result is a concrete mixture (RF patent No. 2149851), including, wt.%: Portland cement 22.3-24; aggregate - sand and crushed stone 67.0-72.0; pigment 0.67-1.22; a plasticizer 0.11-0.21 selected from the group: superplasticizer C-3 based on the condensation product of the sodium salt of naphthalenesulfonic acid and formaldehyde; a mixture of C-3 superplasticizer with a 50% aqueous solution of polyvinyl acetate emulsion in the ratio of 3.33-4.7: 1, the same mixture with epoxy resin and amine hardener, the rest is water. The compressive strength of concrete is up to 72.0 MPa, frost resistance up to 300 cycles, the structural viscosity of the concrete mix is up to 1100 Pa · s, the cone draft is 9 cm.

The disadvantage of this mixture is the low ductility of the resulting concrete. The tasks solved by the invention are:

- an increase in the solidity of concrete, the effectiveness of defoaming and acceleration of hardening of concrete in the early days;

- ensuring the compatibility of the processing aid with plasticizer solutions (C-3 superplasticizer, lignosulfonates, etc.).

The tasks are solved in that the concrete mixture containing aggregate - sand and gravel, plasticizer, cement, water, additionally contains a technological additive - the product of the interaction of triethanolamine and higher unsaturated fatty acids, mainly oleic and linolenic acids, or their mixture with saturated fatty acids in which the content of unsaturated fatty acids is not lower than 80%, with a molar ratio of triethanolamine and higher unsaturated fatty acids from 1: 0.8 to 1: 1.35 and the following concrete mixture, kg / m ³ : cement - 350-362, ne juice - 735-770, crushed stone - 1072-1120, water - 168-181, plasticizer - 0.35-0.60, the specified additive - 0.0006-0.008% by weight of cement.

The synthesis of a technological additive — triethanolamine esters — was carried out in a pilot plant or in a laboratory reactor equipped with a reflux condenser, a refrigerator, and a distillation tank. Triethanolamine, unsaturated fatty acids and up to 0.2% of conventional polyester synthesis catalysts were loaded into the reactor in the required ratio (see Table 1), they turned on heating, raised the temperature of the reaction mass to 180-190 ° С and kept the reflux number at 0, 3-0.7. After holding at this temperature and reaching an acid number of not more than 50 mg KOH / g, vacuum was applied and the reflux at the reflux condenser was increased to 1.0-1.5 and by the end of the process to 2-3. When the acid value was less than 2.5 mg KOH / g, the reaction mixture was cooled and the finished product was analyzed. Product specifications are given in table 1.

Table 1
Synthesis of a technological additive with a different molar ratio of triethanolamine - unsaturated acid (A / (B + C + D)).
Components: A-Triethanolamine, B-oleic, B-linoleic. G-linolenic, D-synthetic fatty acids fractions (C ₁₀ -C ₁₆ ) (saturated) No. No. Additives Mole components The molar ratio A / (B + C ++ D) Product Performance BUT B AT G D %IT c.h.mg
KOH / g one P-1 1.00 1,1 - - 1: 1,1 3.0 1,2 2 * P-2 1.00 0.39 0.35 0.06 0.25 1: 0.80 4.0 1,5 3 P-3 1.00 0.53 0.49 0,03 - 1: 1.05 6.06 1.8 four* P-4 1.00 0.68 0.62 0.05 0.30 1: 1.35 3,7 2,4 * In example 2, the content (B + C + D) is 80%, in example 4 - 81%.

The synthesized products were used for comparative tests in concrete mixtures together with plasticizing additives. The test plasticizers used were C-3 superplasticizer (a salt of a high molecular weight condensate of naphthalene sulfonic acid and formaldehyde, in particular sodium polynaphthalene methyl sulfanate) and lignosulfonate.

For each example, a series of samples was prepared on the same raw material. For testing and comparison, samples of concrete solutions were prepared and measured: cone sediment, air content, compressive strength at the age of 1, 3, 7, 14, 28 days. A concrete solution was prepared as indicated in table 2.

The amount of technological additives was varied within 0.1: 6% by weight of the C-3 superplasticizer or lignosulfonates (0.0006-0.008% by weight of cement). The quality of concrete mixtures was characterized by composition, measurement of cone precipitation, air content and density of the concrete mixture. The rate of hardening of concrete was determined by measuring the compressive strength at the age of 1, 3, 7, 14, 28 days.

As can be seen from examples 1-4, shown in table 2, technological additives according to the invention are highly effective and can be used in amounts of less than 0.001% by weight of cement. In such quantities, they provide an increase in strength in the first 1-7 days (in comparison with a concrete mixture containing only plasticizers) by 10-18%, with a low air content of less than 2.3%.

In addition to the properties of defoaming and hardening acceleration, technological additives according to the invention provide high monolithic concrete. Examples 5, 6 illustrate this property. The density of concrete, determined according to GOST 10181-2000, using the technological additive according to the invention when using plasticizers C-3 or its mixture with lignosulfonate is higher not only in relation to concrete with plasticizing additives, but also to concrete without plasticizing additives. High density of concrete provides not only high strength of concrete (see table 2), but as a result of this high resistance to all types of corrosion damage, i.e. provides increased durability of concrete structures.

Claims (1)

A concrete mixture containing aggregate - sand and gravel, plasticizer, cement, water, characterized in that it additionally contains a technological additive - the product of the interaction of triethanolamine and higher unsaturated fatty acids or their mixture with saturated fatty acids, in which the content of unsaturated fatty acids is not lower 80%, with a molar ratio of triethanolamine and higher unsaturated fatty acids from 1: 0.8 to 1: 1.35 and the following concrete mix, kg / m ³ : Cement 350-362 Sand 735-770 Crushed stone 1072-1120 Water 168-181 Plasticizer 0.35-0.60 The specified additive,% by weight of cement 0,0006-0,008