RU2342347C2 - Method of preparation of dry fine frothing agent and method of preparation of dry raw mix for foam concrete with use of this frothing agent - Google Patents

Abstract

FIELD: building.

SUBSTANCE: inventions are intended for obtaining of a dry frothing agent and a dry raw mix for foam concretes. In method of preparation of dry fine frothing agent, including mixture of a concentrate of a frothing agent with the water-absorbing additive, as the water-absorbing additive use unslaked lime or its mix with silicon dioxide, either semiwater plaster, or the waterproofing additive "Penetron Admix" at a parity of the specified concentrate and the additive 1:1-8, carry out endurance of the obtained mix before end of reaction of hydration. The way of preparation of a dry raw mix for foam concrete includes a dosing and hashing of portland cement and the frothing agent received in the way specified above, at a following parity of components, wt %: portland cement 250-400, frothing agent concentrate 1.1-5.0, the water-absorbing additive 3.0-22.0. The inventions are developed in dependent points.

EFFECT: possibility of long storage of frothing agent and raw mix and accuracy of dosing raw mix component, technology simplification, increase of efficiency of frothing agent, decrease in its expense.

8 cl, 2 tbl

Description

The invention is intended to obtain a dry blowing agent and dry concrete raw mix for foam concrete and can be used in the production of foam concrete building heat-insulating and structural-heat-insulating products, cellular concrete products, walling in monolithic construction.

Most of the known foaming agents are aqueous solutions of substances (see, for example, rosin glue, Morpen foaming agent used in the description of the patent of the Russian Federation No. 2132314, С04В 38/10, “Method for preparing foam concrete, raw mix for preparing foam concrete and method for manufacturing the construction "Published on 06/27/99.). Liquid foaming agents make it difficult to accurately dose the components, for example, in foam concrete mixtures using a one-stage and two-stage preparation technology, which causes great difficulties in the production and instability of the properties of the foam concrete mixture.

The closest analogue of the proposed method for the preparation of the foaming agent is the "Method of producing a foaming agent" according to the patent of the Russian Federation No. 2284308, IPC С04В 38/10, published September 27, 2006.

In accordance with the above known technical solution, the method for producing a foaming agent includes hydrolysis of animal feed in the presence of alkali to obtain an extract, neutralizing the extract with strong acid, stabilizing with a strong acid salt and dehydration, while after stabilization the extract is cooled and dehydrated by mixing it with a dispersant (adsorbent as water-absorbing additive) in an amount of 1: 20-1: 100 to the amount of extract by weight and drying to obtain a mixture with a moisture content of 1-5%. The dispersant is used with a specific surface area of 350-1000 m ² / m ³ . As a dispersant, a mineral or organic substance with dispersing and sorption properties was used, such as finely ground minerals (chalk), mineral fibers (basalt), various silica-containing substances (silica fume), silica gel, white soot, finely ground window or container glass, finely ground clay, alumina-containing substances (alpha corundum), titanium dioxide, zinc dioxide, wood flour, textile dust, etc., as well as a mixture of dispersed substances.

The disadvantage of this method is to obtain a foaming agent of a sufficiently high humidity of 1-5%, which leads to its clumping, clumping of the binder when it is added to the mixture with the foaming agent of the specified moisture content and clumping of the mixture itself, reducing their dispersion and the inability to prepare a dry concrete mixture with long-term storage and its subsequent simple use for the preparation of foam concrete. Clumping of the concrete mixture and its components leads to a violation of the uniformity of the structure of the foam concrete from the mixture with such a foaming agent, requires more careful and longer mixing of the concrete mixture with water during the preparation of the foam concrete, does not provide a stable, non-shrinkable foam concrete.

Another disadvantage of this method is the low efficiency of the foaming agent, which requires its use in foamed concrete in an amount of 10-30 kg / m ³ , which leads to a violation of the aggregate stability of the concrete mixture and to a significant deterioration in the strength characteristics of the foam concrete.

The objective of the invention is to develop a dry, solid foaming agent for long-term storage without clumping, the use of which in dry mixtures of long-term storage for the preparation of foam concrete would increase the manufacturability of their preparation, ensure accurate dosing of the initial components of the foam concrete, obtain a stable, uniform, non-shrink, more durable foam concrete. Another objective is to increase the efficiency of the foaming agent, reducing the amount of its use per unit volume of foam concrete.

The problem is solved in a method for preparing a dry finely divided foaming agent by mixing an aqueous solution of a foaming agent (its concentrate) with a water-absorbing additive. An adsorbent in the form of chalk is used as a water-absorbing additive. The difference from the prototype is the use of not only chalk, but also other adsorbents of carbonate rock, or hydrating additives that enter the foaming solution with water into a hydration reaction to produce a solid product, as the water-absorbing additive, and the aqueous solution of the foaming agent in relation to the water-absorbing additive is taken in the ratio of 1 : 1-1: 8. As a water-absorbing additive - an adsorbent in the form of a carbonate additive - use finely ground chalk or limestone, or dolomite. As hydrating additives, a waterproofing additive in the form of Penetron Admix, quicklime, lime-silica binder (ground mixture of quicklime with silica), produced, for example, by the Kazan Silicate Plant for the production of silicate brick, is used. As a water-absorbing additive that enters the hydration reaction, you can use gypsum hemihydrate, which turns into a two-water gypsum as a result of the hydration reaction. The resulting mixture of a foaming agent with a hydrating additive is kept for 3-7 hours until the completion of the hydration reaction. The exposure time depends on the time of complete completion of the hydration reaction associated with the type of hydrating additive. When using an adsorbent, if necessary, the mixture is dried by heating in a drying chamber at a temperature of 105-200 ° C until a dry foaming agent mixture is obtained, while the heat treatment time is determined experimentally, which depends on the volume of the mixture and the ratio of its components. With a high ratio of adsorbent and foaming agent 8: 1 and a high specific surface area of the adsorbent of 2000 cm ² / g, heat treatment is optional. As a result of using the described method for preparing a foaming agent using a water-absorbing additive, water is bound and removed from the foaming agent and a dry solid product with a moisture content of not more than 0.5% is formed. The low humidity of the dry blowing agent does not lead to clumping and clumping of the components of the dry mix, for example binders, ensuring uniformity of the dry mix, uniformity of foam concrete from them, the stability of their properties and increase the strength of foam concrete.

Known methods for the preparation of foam concrete, in which the method of preparing the raw material mixture for non-autoclaved foam concrete involves dry mixing Portland cement of 31-56 wt.%, Siliceous aggregate in the form of silica sand or fly ash 16-44 wt.%, Complex additives of complex composition with aluminum sulfate, semi-aquatic gypsum, alkali metal carbonate, calcium chloride. The preparation of the cement dough is carried out by adding water to the resulting mixture, the preparation of the foam by adding a foaming agent based on secondary sodium alkolsulfites of 0.05-0.15 wt.% To the water, mixing the cement dough and foam and then molding the resulting concrete mixture (see application No. 97111476 for the grant of the patent “Raw mix for the manufacture of foam concrete, IPC S03B 38/10, published on 09/10/99.).

There is also known a method of preparing a raw material mixture for foam concrete in accordance with the patent of Russian Federation 2132314, С04В 38/10, "A method of preparing foam concrete, a raw material mixture for preparing foam concrete and a method of manufacturing a structure" published on 06.27.99., Which includes the phased separate introduction of dry components and mixing Portland cement 48-60 wt.%, siliceous filler 12-34 wt.% in the form of fine sand, foam stabilizer 0.06-0.08 wt.% from sodium silicate, lime 0.08-0.12 wt. %, anti-shrink additive TIAMAK 0.12-0.16 mA .% Setting accelerator Pozzolit and 0.04-0.06 wt.%.

The disadvantage of the above methods of preparing the raw mix is that it is necessary to form building products from the mixture immediately after mixing the components, since water enters there. It is difficult to dose the complex composition of the mixture components at the construction site, special equipment, qualified personnel are required, therefore, such foam concrete and products are made from them in the factory. In addition, there is a technological problem of introducing a foaming agent into the mixture, mixing it with other components of the mixture, because its stability is not high enough, which leads to shrinkage of foam concrete products.

The closest analogue is the method of preparing the concrete mixture for foam concrete in the form of a solution according to the patent of the Russian Federation No. 2284308 "Method for producing a foaming agent", IPC С04В 38/10, published on September 27, 2006. In accordance with the specified patent for the production of foam concrete, a concrete mixture containing a binder, for example Portland cement, a dry blowing agent with a moisture content of 1-5%, is loaded into a foam mixer, add the calculated amount of water and mix until foaming (see paragraph 3, 8 page 3 of the description, etc. .). Depending on the type of foam concrete per 1 m ³ it takes from 10 to 30 kg of foaming agent.

The disadvantage of this method is that it is impossible to prepare a dry concrete mixture of long-term storage with a foaming agent, dried to 1-5% humidity, because such a foaming agent crumbles, and its use in dry concrete mixes also leads to clumping of the binder in the concrete mix, clumping of the driest concrete mix, reduction of their dispersion, violation of the uniformity of the foam concrete structure, requires more thorough and longer mixing of the concrete mix with water during the preparation of foam concrete. Violation of the homogeneity of the structure of foam concrete leads to instability of the characteristics of foam concrete, its insufficient strength, and shrinkage.

The objective of the invention is to create a dry concrete mixture of long-term storage for the preparation of foam concrete of a homogeneous structure, making it possible to easily prepare foam concrete directly from the construction site using simple equipment by mixing the finished dry raw mix with water. Another objective is to increase the stability of the characteristics of foam concrete and reduce its shrinkage due to the formation of a more uniform structure, increase the strength characteristics of foam concrete by reducing the moisture content of the used foaming agent, reducing its clumping and clumping of the binder and the concrete mixture itself.

The problem is solved by a method of preparing a dry raw mix for foam concrete, including pre-mixing an aqueous solution (concentrate), a foaming agent with a water-absorbing additive, dosing components: a binder in the form of Portland cement and a foaming agent in dried form. If necessary, to obtain more dense and durable structural and heat-insulating products add siliceous aggregate (sand). The difference between the proposed method for the preparation of this mixture from the prototype is that an aqueous solution, preferably a concentrate, a synthetic foam former PB-2000 or protein PO-6 is used as a foaming agent, not only a mineral adsorbent in the form of a finely ground carbonate additive - chalk is used as a water-absorbing agent, but also other finely ground carbonate additives in the form of limestone or dolomites, or they use a finely ground hydrating additive - quicklime, or a mixture of calcareous silica general in a ratio of 1: 1, or gypsum hemihydrate or a waterproofing additive. The foaming agent is mixed with a water-absorbing additive in a quantitative ratio of 1: 1-1: 8 to obtain a solid product, if necessary, dried by heat treatment of a mixture of a foaming agent with a carbonate additive. With a hydrating additive, the foaming agent mixture is maintained until the hydration process is completed. Mix the dry components: foaming agent and binder. Additionally, an anionic type surfactant (hereinafter referred to as a surfactant) can be added to the composition. The components are taken in the following quantitative ratio, parts by weight:

Portland cement 250-400 Foaming agent 1.1-5.0 Water absorbing additive 3.0-22.0.

Water is added to the obtained dry raw mix directly during the preparation of foam concrete, already at the construction site.

Surfactant of the anion type is taken in an amount of 0.15-4.5 parts by weight; siliceous aggregate - 60-200 wt.h. if necessary, to obtain more dense foam concrete.

The quantitative ratio of the foaming agent and the water-absorbing additive depends on the type of foaming agent, its concentration, the type of water-absorbing additive, its water-absorbing properties.

Processing the foaming agent with a water-absorbing additive before mixing it with other components of the raw material mixture allows you to bind the moisture contained in the foaming agent and use the latter in the form of a solid dry substance, to ensure long-term storage of the dry raw material mixture without clumping. In the preparation of foam concrete from a dry raw mix in accordance with the invention, there is a separation in time of the processes of thoroughly mixing the dry components and the foaming processes when water is mixed with the already obtained dry mixture with a binder, such as cement. This leads to stabilization of the foam concrete mixture, a decrease in its shrinkage and an increase in strength properties.

Portland cement ПЦ 500 DO-Н was used as a binder; it has an additive-free and normalized clinker composition of the Volsky cement plant GOST 10178 containing tricalcium aluminate (Ca ₃ A) not more than 6%, grinding fineness - total residue on sieve 008 not more than 15% with a specific surface of 3000 -3500 cm ² / g.

As the foaming agent used, the synthetic foaming agent PB-2000, TU 2481-185-05744685-01 or the protein foaming agent PO-6CT, TU 0258-148-05744685-95.

As a water-absorbing additive used:

- chalk GOST 17498-72;

- limestone GOST 8267-93;

- Dolomites GOST 23672-79;

- quicklime construction GOST 0179-77;

- a mixture of lime with silica - lime-silica binder produced by Kazan Silicate Plant;

- gypsum hemihydrate - gypsum binder for construction purposes G4-G7 GOST 125-79;

- waterproofing additive Penetron Admix, TU 57775-001-39504194-96.

As anionic surfactants, washing powders were used - various powdered detergents of Kazan OJSC NEFIS.

As a siliceous component used sand of the group "fine" GOST 8736.

In RU 2132314, lime was also used in the preparation of the raw material mixture, as in one of the variants of the proposed method, however, lime in this analog acts as a foam stabilizer, allows to reduce the shrinkage characteristics of foam concrete by stabilizing the structure of the foam. Unlike RU 2132314, one of the options of the proposed method uses quicklime, which, when interacting with the moisture of the foam concentrate, chemically binds it, serves as a water absorber in a new set of features, leads to a new technical result of obtaining a dry blowing agent, which ultimately provides dry raw mix for foam concrete.

A method of obtaining a raw mix for foam concrete based on it is as follows.

Pre-prepare a dry mixture of foaming agent. To do this, the estimated amount of the foaming agent concentrate is thoroughly mixed with a pre-ground water-absorbing additive in the specified ratio of 1: 1-1: 8. When necessary, using this adsorbent, this mixture is dried in a drying chamber at a temperature of 105-200 ° C until a dry foaming agent mixture is obtained, while the heat treatment time is determined experimentally, which depends on the volume of the mixture and the ratio of its components. Depending on the type of water-absorbing additive used, when mixed with a foaming agent concentrate, various reactions proceed. When using a carbonate additive in a mixture with a foaming agent, its porous particles adsorb the water molecules of the foaming agent, which are subsequently removed by heat treatment. With a specific surface of a water-absorbing additive of 2000 cm ² / g, its high content in a mixture with an 8: 1 foaming agent, heat treatment is not required. When using quicklime, the hydration reaction proceeds using moisture in the blowing agent concentrate. For the complete hydration reaction to take place after mixing, the mixture should be aged 3-7 hours. When using gypsum hemihydrate or a waterproofing additive, a hydration reaction also occurs. The reaction time of the gypsum hydration reaction and the required exposure time of the foaming agent mixture are affected by its brand. Next, the dry foaming agent mixture is sieved through a sieve 09 to obtain a mixture with a specific surface area of 2000 cm ² / g When gypsum hemihydrate is used, in the process of its interaction with the foaming agent moisture, a gypsum stone is formed, which must be ground before sieving. After preparing the required amount of dry blowing agent, Portland cement is metered and thoroughly mixed with the calculated amount of the obtained dry blowing agent. If necessary, add other dry dosed components: a powdery detergent that reduces the surface tension of the mixing water, a siliceous component for denser concrete. To prepare foam concrete based on the obtained dry concrete mixture, 105-280 parts by weight of water are supplied to the turbulent mixer. and dry raw mix is added to it, mixed at a stirrer speed of 1500 rpm for at least 5 minutes. These operations can be done directly at the construction site. For pumping foam concrete to the molding site, it is possible to use pressure regulators with a pressure of 1.5 atm. After molding, to reduce shrinkage, it is desirable that the foam concrete hardens for the first 3-4 hours at a temperature of 30-40 ° C.

Depending on the qualitative and quantitative ratio of the components, different compositions of dry raw mixes of long-term storage for foam concrete were obtained, which are reflected in Examples 2-22 of Table 1. In example 1 of Table 1, data on the analogue of RU 2132314 are given, in example 23, data on the prototype RU 2284308. Table 2 shows the characteristics of foam concrete from raw mixes, including from dry raw concrete mix in accordance with the invention (examples 2-22). In the prototype example 23, heat-insulating structural foam concrete with a density of 600-800 kg / m ^{3 was used} ; for the invention, examples 2-22 prepared dry raw mixes for both light, heat-insulating and dense, structural and heat-insulating foam concrete. Comparable with the prototype in table 2 can only be dense, heavy concrete with a density close to it of 600-800 kg / m ³ . The density and compressive strength of foam concrete were determined in accordance with GOST 10180-90, the shrinkage was determined in accordance with GOST 25485-89, Appendix 1. As can be seen from Table 2, with respect to the analogue of RU 2132314, the compressive strength of foam concrete in accordance with the invention increased even without using siliceous aggregate, shrinkage decreased in all examples. With a comparable density of foam in accordance with the prototype, the compressive strength of foam in accordance with the invention increased, shrinkage decreased. In general, the foam concrete brand has risen. For the preparation of foam concrete per unit volume in accordance with the invention of the foaming agent, 5-15 kg / m ³ is required, which indicates its greater efficiency in relation to the prototype and the greater efficiency of foam concrete.

Table 1 Composition number Portland cement Foaming agent Carbonate additive Quicklime A mixture of lime and silica Semi-aquatic gypsum Waterproofing additive Surfactant Silica PB-2000 Other PO-6 a piece of chalk dolomite limestone 1 RU 2132314 45 - Morpen - - - - Lime 0.07 - - - - 26 2 250 5,0 10.0 0.15 3 300 4.4 8.8 four 300 4.4 8.8 5 350 1,875 13,125 6 400 3.14 21.98 7 300 2.08 10.42 8 300 3,125 9.0 9 300 5,0 15.0 60 10 300 2,5 10.0 eleven 300 1.26 10.1 12 300 1,5 10.5 13 300 1,875 13,125 one hundred fourteen 300 4.2 8.2 fifteen 300 2,5 7.5 16 350 5,0 15.0 17 300 4.1 8.3 eighteen 300 4.1 8.3 2.0 19 350 3,5 3,5 twenty 350 4.4 8.8 200 21 350 1.7 3.0 4,5 140 22 350 1,6 12.8 23 Prototype RU 2284308 370-420 From raw materials of animal origin 4.5-5.0 - 90-100 - - - - - - - 200-300

table 2 Characteristics of Foam Concrete 1 analogue of RU 2132314 2 3 four 5 6 7 8 9 10 eleven 12 13 fourteen fifteen 16 17 eighteen 19 twenty 21 22 23 Prototype RU 2284308 Density, kg / m ³ 450-500 260 440 430 550 750 540 500 700 410 470 460 550 405 435 550 440 380 380 650 620 670 600-800 Compressive strength, R ₂₈ kg / cm ² 1.5-1.6 1-4 7.4 7.7 23.5 37,2 19.1 15.0 29.2 8.2 16,2 11.9 15.0 7.1 6.9 14.0 8.5 8.9 7.0 14.3 13.7 29.2 10-25 Shrinkage, mm / m after 28 days under normal conditions 3.8 2.9 2.1 1.9 1.4 0.9 1,5 1.7 1.9 2.2 2.0 1,5 1.3 2,8 1,5 3.0 2.0 1.7 2.9 2.1 2,4 2.0 2,5

Claims (8)

1. A method of preparing a dry finely divided foaming agent, comprising mixing a foaming concentrate with a water-absorbing additive, characterized in that quicklime or its mixture with silica, or semi-aquatic gypsum, or Penetron Admix waterproofing additive are used in the ratio of the said concentrate to the additive 1: 1-8, carry out the exposure of the mixture to complete the hydration reaction. 2. The method according to claim 1, characterized in that after exposure, grinding is carried out. 3. The method according to claim 1, characterized in that the PB-2000 synthetic blowing agent or PO-6 protein blowing agent is used as the foaming agent concentrate. 4. A method of preparing a dry raw mix for foam concrete, comprising dosing and mixing Portland cement and a foaming agent obtained by the method according to claim 1, in the following ratio of components, parts by weight: Portland cement 250-400 blowing agent concentrate 1.1-5.0 water absorbing additive 3.0-22.0 5. The method according to claim 4, characterized in that after the exposure is carried out grinding. 6. The method according to claim 4, characterized in that the PB-2000 synthetic blowing agent or PO-6 protein blowing agent is used as the foaming agent concentrate. 7. The method according to claim 4, characterized in that it additionally use a surface-active substance of the anion type in an amount of 0.15-4.5 wt.h. 8. The method according to claim 4, characterized in that it additionally uses siliceous aggregate in an amount of 60-200 wt.h.