RU2532816C1 - Complex additive for concrete mixtures and mortars - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to building equipment and can be applied in the production of concrete products for the improvement of their basic physical-chemical properties. The complex additive for concrete mixtures and mortars contains a superplasticiser C-3, a mixture of Iceland spar, aluminium sulphate and fine-grained pyrite in a ratio, wt %: superplasticiser C3 10-30, Iceland spar 50-80, aluminium sulphate 5-7.5, fine-grained pyrite 5-7.51.

EFFECT: improvement of basic properties of concrete: increase of strength and reduction of moisture permeability.

1 dwg, 1 tbl

Description

The invention relates to the building materials industry, in particular to concrete mix for the manufacture and production of concrete and reinforced concrete products with increased service life by reducing the water resistance of concrete, for high-rise construction, to increase the bearing capacity of facades.

Concrete used in hydraulic engineering and road construction has high demands on durability, which, first of all, is evaluated for frost resistance and water tightness of concrete. The modern variety and complexity of technical problems form new challenges for improving building materials used in various fields. One of the solutions to such problems is the creation and use of new complex additives for concrete mixtures and mortars, rationally combining the necessary technological and operational characteristics.

Water resistance is a very important characteristic of concrete, not only used in hydraulic structures, for example for dams, reservoirs, pools, bridge supports, but also in everyday construction. Repeated penetration of moisture into the pores of concrete and its freezing leads to the appearance of cracks in the concrete stone and a decrease in the strength of concrete.

Water permeability of concrete

Filtration of water in medium-density concrete can occur mainly bypassing the cement stone along microcavities at the points of contact of the cement stone and aggregates formed as a result of internal water separation during the sedimentation of cement paste or uneven shrink stresses, as well as through pores and capillaries in the cement stone. The general porosity of concrete and its permeability are ambiguous concepts. Concrete can have sufficient porosity and at the same time have low permeability. Thus, capillaries with a diameter of up to 1 μm are practically impermeable to water, since the adsorption layers of the water of the wall layer narrow the living section of the capillaries by approximately 0.5 μm and sometimes completely overlap them, making it difficult to filter water through these capillaries. However, the movement of water in concrete can occur not only purely mechanically, as a result of direct filtration in the presence of pressure, but also due to diffusion processes. Moisture transfer in the thinnest capillaries, called capillary moisture permeability, can take place in a sufficiently dense cement stone and concrete, for this only a small moisture or thermal potential is required. The intensity of migration or capillary suction depends on the shape and diameter of the capillaries.

Obtaining practically waterproof concrete is ensured by the necessary cement content in concrete, which depends on the granulometric composition of aggregates, a small water-cement ratio and a corresponding water content in the concrete mixture during molding in molded concrete units, as well as an optimal moisture setting of concrete hardening, which allows to extend the hydration process. Water permeability can be sharply reduced in some cases when surfactants are added to concrete, both hydrophilic and hydrophobic. So, with the introduction of surface-active additives into concrete, the water permeability of concrete is significantly (10-20 times) reduced. This effect of additives is explained by a change in the structure of cement stone due to a decrease in the water demand of the concrete mixture and a decrease in water separation by the cement paste. In turn, this leads to a decrease in the number and size of pores in the cement stone and to improved contact of the latter with aggregate grains. Although with the introduction of additives involving air, the total number of pores increases slightly, but these micropores, being closed, block the communication between individual capillaries and reduce the capillary permeability of concrete.

In the modern market of building materials, there is a need for particularly strong and heavy concrete containing aggregates, for example barite, limonite, and used for the manufacture of various building parts and structures with a bulk density of concrete Y _o = 3000-3300 kg / m ³ , for example, massive foundations, test benches, various weights, balancers, etc.

Known concrete mixture for the manufacture of products and structures made of heavy concrete, including high-calcium fly ash, crushed stone, sand, chloride-containing additive and water (RU 2101251 C1, C04B 28/08, 08/15/1995). The specified mixture does not allow on its basis to obtain structures with a bulk density in the range of 3000-3300 kg / m ³ , and a chloride-containing additive can cause corrosion of the reinforcing cage of the concrete product.

A concrete mixture is known, including hydraulic cement, barite, fly ash, as well as various chemical additives, including those based on carboxylates and sulfonates (GB 1413121, C04B 28/04, 11/05/1975).

The specified mixture provides structures with a bulk weight of 3000-3300 kg / m ³ , but does not adequately provide other characteristics of concrete: mobility and storage for long-distance transport.

The problem is solved in that the concrete mixture includes clinker cement of normalized composition ПЦ 500Д0-Н, barite concentrate of various fractions, fly ash (powder from production waste), as well as complex chemical additives based on polycarboxylates and lignosulfonates, in the following ratio of components, wt.%

Portland cement PC 500D0-N 10.9-11.5 fly ash 0.97-2.4 barite concentrate 79.1-80.72 additives: polycarboxylates 0.11-0.16 and lingosulfonates 0.01-0.02 water 6.76-6.88

The essence of this invention lies in the fact that, reducing the cost of cement and water per unit volume (m ³ ), the released part of the volume of the mixture is filled with barite concentrate, thereby increasing the specific gravity of the concrete mixture. The specified composition of the concrete mixture for the manufacture of heavy concrete can increase the average density and strength of the material, as well as expand the raw material base by reducing the dosage of the lightest components of the concrete mixture, in particular water. The concrete mix for the manufacture of this concrete is intended for building structures with increased bulk density, includes Portland cement made of clinker of standard composition, weighted aggregate (barite or limonite concentrate with a density of at least 3.8 g / cm ³ ) of various fractions depending on the purpose of the concrete mixtures, conditions of transportation and styling. The concrete mixture also includes dry fly ash from electrostatic precipitators of thermal power plants resulting from the burning of coal in a dusty state, i.e. waste from fuel combustion is used, thereby improving the environment. In addition, polycarboxylate-based superplasticizers are used in the concrete mix.

The ratio of the components of the concrete mixture is by weight in%: cement ПЦ 500Д0-Н 10.9-11.5 wt.%, Barite concentrate 79.1-80.72 wt.%, Fly ash 0.97-2.4 wt. %, polycarboxylates 0.11-0.16 wt.%, lignosulfonates 0.01-0.02 wt.% and water 6.76-6.88. Water is dosed depending on transportation conditions, concrete mix laying, required strength, etc. Cement ПЦ 500Д0-Н must meet the requirements of GOST 10178, barite concentrate - GOST 4682, fly ash - GOST 25818.

Fly ash has the following chemical composition: SiO ₂ 46.44%; Al ₂ O ₃ 10.86%; Fe ₂ O ₃ 10.00%; CaO 22.15%; MgO 5.98%; SO ₃ 2.17%; TiO ₂ 0.60%; Na ₂ O 0.74%; K ₂ O 0.56%. The specific surface is 374 m ² / kg. The residue on the sieve is 008-7.0%.

The use of fly ash in this composition of concrete mix for the manufacture of heavy concrete allows, in addition to recycling production waste, to obtain a denser structure of concrete, reduce cement consumption or increase its strength characteristics, as well as improve the technological properties of concrete mix.

Disadvantages - relatively low strength and high moisture permeability.

Known mineral additive for concrete according to the patent of the Russian Federation for the invention No. 2478589, IPC C04B 7/12, publ. 04/10/2013

The technical result is a decrease in the content of alkaline oxides in the liquid phase of cement and obtaining high-quality cement, mortar and concrete with the specified additive without compromising their properties. A mineral cement additive containing cement dust removal of electric filters from rotary kilns additionally contains a component with a specific surface area of at least 800 m ² / kg, at least one selected from the group: chalk, clay, limestone, with a ratio between the specified component and dust from 1: 1 to 1:10, while the content of R ₂ O in terms of Na ₂ O in the additive is not more than 4%. The additive may contain as the specified component dust from the electrostatic precipitators of the unit for joint drying and grinding of cement raw materials.

Disadvantages - the basic characteristics of concrete are not improved

Known additive for concrete according to the patent of the Russian Federation for the invention No. 2478589, IPC C04B 7/12, publ. 04/10/2013

Effect: obtaining an environmentally friendly mixture of substances used as an additive, which helps to increase the flexibility of concrete and reduce shrinkage. The mixture of substances used as an additive for cured materials, in particular for concrete mix, contains, wt.%: Xanthan gum 1-8; pseudo-viscous thickener containing water, 1-6; thinner 2-10; synthetic resin compatible with cement, 20-50; foaming agent 0.1-3; curing accelerator 30-70, a preservative of 0.2-4, and the total weight of all components of the mixture of substances should be 100 wt.%. The use of the specified mixture of substances for a concrete mixture containing 0.01-0.5 kg, preferably 0.05-0.1 kg per kg of cement, a mixture of substances, cement, aggregate. The above concrete mixture containing as aggregate any kind of sand, any kind of soil, contaminated or uncontaminated, and / or materials such as bauxite, laterite, volcanic ash, pumice and ash from incinerators.

Disadvantages - the basic characteristics of concrete are not improved: strength and moisture resistance.

Known complex additive for concrete according to the patent of the Russian Federation for the invention No. 2457190, IPC C04B 22/08, publ. 07/27/2012

The technical result is an increase in the growth rate of concrete strength in the early stages of hardening while maintaining its high final strength, ensuring frost resistance and water resistance. The complex additive for the concrete mixture contains, wt.%: Phenylethoxysiloxane 2-4, carboxylate polyester 30-35, hardening accelerator 61-68.

The disadvantages are that despite the accelerated growth in strength, the level of concrete strength did not increase and the moisture permeability did not change.

Known complex additive for concrete mix according to the patent of the Russian Federation for the invention No. 2443648, IPC C04B 24/24, publ. 02/27/2012

The technical result is the preservation and improvement of the technological properties of the concrete mixture and the increase in compressive strength of cement stone and concrete with a more rational use of plasticizing additives. The complex additive for concrete mix contains, wt.%: Melflux 265IF - 50-75, polyethylene glycol-PEG 2000 - 25-50.

Disadvantages - the use of expensive imported fillers and poor moisture resistance of concrete.

Known complex additive for Portland cement according to the patent of the Russian Federation for the invention No. 2431623, IPC C04B 22/00, publ. 10.20.2011 g.

The complex additive for Portland cement contains, wt.%: Gypsum or anhydrite 30-54, superplasticizer C-3 0.5-4.5, blast furnace dust 10-25, ash and slag waste with an alumina content of at least 25 wt.% 16.5 -52.5, carbonate rock 12-35. The technical result is an increase in the degree of expansion of Portland cement with increased hydraulic activity, a decrease in the porosity of concrete on Portland cement with the specified additive.

Disadvantages - low strength and high moisture resistance of concrete.

Known complex additive for concrete mix according to the patent of the Russian Federation for the invention No. 2422395, IPC C04B 24/24, publ. 06/27/2011

The technical result is an increase in the strength of concrete in the early stages of hardening while maintaining their high final strength, increasing frost resistance and water resistance. The complex additive for concrete mix contains, wt.%: “Mobet brand 2” hyperplasticizer - 33-40, hardening accelerator “Mobet brand 3 economy” - 60-67.

The disadvantage is the high moisture permeability of concrete.

Known modifier of concrete and the method of its production according to the patent of the Russian Federation for the invention No. 2421424, IPC C04B 22/00, publ. 06/20/2011

EFFECT: increased concrete tensile strength and axial tensile bending, enhanced passivating properties of concrete in relation to steel reinforcement. In the method of producing a concrete modifier, including the combined dry grinding of bauxite sludge and an organic additive, bauxite sludge from the production of alumina by the alkaline method is used, as an organic additive, a powdery plasticizer is one of the group: sulfonated melamine or naphthalene formaldehyde, modified lignosulfonate, polycarboxylate, indicated carried out in a percussion apparatus at a particle velocity of 100-400 m / s to a particle size of 15-30 microns

Disadvantages - low strength and moisture permeability of concrete.

The use of urea (urea) as a modifier that accelerates the setting of concrete mixes and hardening of concrete is known (GOST 2081-75, also VG Batrakov. Modified Concretes, M., 1998, p. 746).

It is known to use polyethylene oxide (polyoxyethylene, polyethylene glycol) as a modifier of the stabilizing, water-retaining effect and improving the pumpability of concrete mixtures (GOST 2081-75, also VG Batrakov. Modified concretes, M., 1998, p.745).

It is known the use of polyethylene oxide in the composition of complex additives for concrete (ed. St. USSR No. 14447779, publ. In 1988; 1143719, publ. In 1985), reinforcing the plasticity of the concrete mortar, its strength and frost resistance. It is known to use polyethylene oxide with a molecular weight of (4.1-6.0) · 10 ⁶ as an organic additive for a heat and sound insulating construction mixture to improve stackability and volume uniformity.

A common disadvantage of these compositions are low strength indicators when applied in concrete compositions, as well as low frost resistance.

Known complex additives for concrete mixtures and mortars according to the patent of the Russian Federation for the invention No. 2479522, IPC C04B 24/18, publ. 04/20/2013

Effect: increase the frost resistance of concrete in salts and increase the strength of concrete at the age of 28 days. The complex additive contains (parts by weight): superplasticizer C-3 5-50, isopropyl alcohol 10-55, urea 5-45. In the particular case of carrying out the invention, the complex additive contains (parts by weight): superplasticizer C-3 10-30, isopropyl alcohol 10-55, urea 5-45, ballast salts of coke oven gas purification based on thiosulfate and sodium thiocyanate 5-50.

The disadvantage is the high moisture permeability of concrete.

Known complex additive for concrete mix and mortar containing a mixture of sodium salts of polymethylene naphthalene sulfonic acids sold under the trade name superplasticizer C-3, and a mixture of ballast salts of coke oven gas desulfurization based on thiosulfate and sodium thiocyanate according to RF patent No. 2228306 (publ. In 2004 ) Significant disadvantages of this complex additive are insufficient strength in the early stages of hardening and low frost resistance in salts.

It is known to use C-3 superplasticizer as an additive (Ukrainian patent No. 24298, publ. In 1998). Superplasticizer C-3 is added to the concrete mixture in an amount of 1.35-1.65 by weight of cement. The known additive causes an increase in the ductile properties of the concrete mixture at a reduced water content, which prevents its delamination during transportation, and also contributes to the production of high-density concrete. Significant disadvantages of the solution of the prototype are insufficient strength in the early stages of hardening and low frost resistance in salts.

Known complex additive containing superplasticizer C-3 and other components according to the patent of the Russian Federation for the invention No. 248208, IPC C04B 24/24, publ. 05/20/2013, The essence of this invention is as follows.

The specified technical result is achieved due to the use of a complex additive C-3 superplasticizer, a mixture of polyethylene glycol and / or polypropylene glycol with a molecular weight of 250-3500 and urea in the following ratio of components (parts by weight):

Superplasticizer S-3 10-30 Polyethylene glycol and / or propylene glycol 5-55 Urea 10-60

In the particular case of the invention, the inventive complex additive further comprises sodium formate in the following ratio of components:

Superplasticizer S-3 10-30 Polyethylene glycol and / or propylene glycol 5-55 Urea 10-60 Sodium formate 5-35

The achievement of the technical result is due to the synergistic effect of the ingredients used.

The following substances may be used to carry out the invention:

Superplasticizer S-3 TU 5745-001-97474489-2007;

Low molecular weight polyethylene glycol TU 2483-71150986-2006;

Polypropylene glycol TU 6-09-2434-81;

Urea GOST 2081-92 "Urea. Technical conditions ";

Sodium formate TU 2432-011-00203803-98.

The advantages of this invention were evaluated by comparison with the prototype of the following indicators: frost resistance in salts (according to the second and third basic methods for determining frost resistance according to GOST 10060-2-95), cone precipitation, concrete density, concrete strength at 28 days.

To study the properties of the claimed additives, a concrete mixture was prepared containing cement 1 part, sand 1.8 parts, crushed stone fractions 5-20 mm 2.8 parts, water 0.4 parts.

This additive was introduced into the concrete mixture with mixing water in an amount of 0.7-2% of the liquid product by weight of cement. Tests of the inventive integrated additives in the composition of concrete mixtures was carried out according to GOST 10181-200 "Concrete mixtures. Test methods ", GOST 10180 - GOST 10060.2-95" Concretes. An accelerated method for determining frost resistance during repeated freezing and thawing. ”

The disadvantages of the prototype are the relatively low strength of concrete and its high moisture permeability.

The objective of the invention, which coincides with the technical result, is to increase the strength of concrete while reducing its moisture permeability.

The solution of these problems was achieved in a complex additive for concrete mixtures and mortars containing S-3 superplasticizer in that according to the invention it additionally contains a mixture of Icelandic spar, aluminum sulfate and finely divided pyrite in a ratio, wt%.

Superplasticizer C3 10-30 Icelandic Spar 50-80 Aluminum sulphate 5-7.5 Fine pyrite 5-7.5

Additionally, the additive may contain calcium hydrosulfoaluminate 10-15, calcium hydrocarbonaluminate 5-7.5 and calcium hydroaluminate 5-7.5%.

The invention is illustrated in the graph (drawing), which shows the change in the strength of the proposed concrete and prototype depending on the percentage of superplasticizer C-3. Line 1 shows the physical properties of the concrete prototype, and line 2 shows the proposed concrete.

Proof of the optimality of the composition of the concrete mixture when using domestic additives and additives C-3: shown in the table.

The preparation of high-strength waterproof concrete with the addition of S-3 superplasticizer and Icelandic spar was carried out in the following proportions per 1 m ³ :

Cement - 315 kg;

Sand - 580 kg;

Crushed stone - 1350 kg;

Water - 156 kg.

Grades of the tested cement M250, M400 and M500.

The complex additive was introduced into the cement mixture in an amount of from 1 to 2% wt., Based on the weight of concrete. The introduction of more complex additives did not give any positive results and increased the cost of concrete work due to the relatively high cost of some components of the additive.

The main data from the table are shown in the graph: line 1 shows the change in the strength of concrete according to the prototype, and line 2 shows the change in the strength of the proposed concrete. The comparison was made for concrete based on cement grade M-400.

It is obvious that the proposed concrete, ceteris paribus, has a strength of at least 10% higher than the concrete of the prototype, in addition, the proposed concrete has a much higher permeability.

findings

The strength of cement M-400 with the use of complex additives is higher than with the use of additives according to the prototype S-3 by 10%.

The optimal range of additives modifier C-3 coincided with the prototype.

The moisture resistance of concrete has increased several times compared to the prototype.

The application of the invention allowed:

- increase the strength of concrete products by 10%.

- reduce moisture permeability several times.

- reduce the cost of complex additives compared to additives based on imported fillers

 .

Test results for complex mixed concrete Substance % % % % % % % % Icelandic Spar,%  85  70  6 7 6 4   61  58  55  70 Aluminum sulfate,%  5  5   5.5 6   6.5 7, 0 7.5 10 Fine pyrite,%  5 5   5.5 6   6.5 7, 0 7.5 10 Superplasticizer, C-3,% 5 10 twenty 24 26   28 thirty 10 Physical properties of concrete based on cement M-250 using the proposed complex additives Compressive strength, MPa 16.6 24.9 26.46 28.02 29.58 31.14 32,7 32.9 Adhesion, kg / cm ² 89.5 92.5 92.8 93.1 93,4 93.7 94.0 98.0 Density, kg / cm ³ 2395 2400 2401 2402 2403 2404 2405 2407 Water resistant W W4 W10 W12 W12 W12 W12 W12 W12 Optimally Physical properties of concrete based on cement M-400 using the proposed complex additives Strength, MPa 48.3 50,5 50.6 50,5 49.9 49.3 49.5 48.3 Adhesion, kg / cm ² 89.5 92.5 92.8 93.1 93,4 93.7 94.0 98.0 Density, kg / cm ³ 2395 2400 2401 2402 2403 2404 2405 2407 Water resistant W W4 W10 W12 W12 W12 W12 W12 W12 Optimally Prototype Physical properties of concrete based on cement M-400 with the use of additives C-3 (prototype) Compressive strength, MPa 44,2 46.2 45.9 45.6 45.3 45.0 44.7 - Water resistant W W4 W4 W4 W4 W4 W4 W4 W4

Claims (1)

A complex additive for concrete mixtures and mortars containing S-3 superplasticizer, characterized in that it additionally contains a mixture of Icelandic spar, aluminum sulfate and finely divided pyrite in the ratio,% wt .:
Superplasticizer C3 10-30 Icelandic Spar 50-80 Aluminum sulphate 5-7.5 Fine pyrite 5-7.5

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