RU2465250C1 - Foaming agent for foamed concrete - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of stable foam used in the industry of construction materials for producing porous materials based on different binding substances (cement, gypsum, soot, clay, as well as hard fibre and other fibres). The foaming agent for foamed concrete contains the following, in wt %: primary C₁₂-C₁₄ sodium alkylsulphates 18.0 - 22.0, higher C₁₂-C₁₄ fatty acids 3.0 - 5.5, carbamide 9.0 - 10.0, butanol 5.0 - 10.0, glycerine 5.0 - 10.0, gelatin 2.0 - 5.0, setting and hardening accelerator 0.5 - 10.0, hard water softening agent 0.0 - 1.0, water - up to 100.0. Technical gelatin T-4 or T-7 can be used. The water softening agent used can be trilon B or sodium phosphate.

EFFECT: obtaining a stable fine form of high density, higher bearing capacity and syneresis time of said foam, low consumption of foaming agent.

3 cl, 1 ex, 3 tbl

Description

The invention relates to the field of producing resistant foams, which are used in the building materials industry to produce porous materials based on various binders: cement, gypsum, soot, clay, as well as fiber and other fibers.

Known foaming agent used in the building materials industry, which contains the following components, wt.%:

C ₁₀ -C ₁₁ alkyl sulfates 10 ÷ 30 higher fatty alcohols fraction C ₁₂ -C ₁₆ 0.5 ÷ 5.0 urea 10 ÷ 30 butanol 5 ÷ 15 water up to 100

(Copyright certificate No. 1291585, bull. No. 7.1987)

The disadvantage of this foaming agent is the low multiplicity of the foam, which causes an increased consumption of the foaming agent, which negatively affects the properties of the foam concrete product, and also causes a large water separation from the concrete dough in the initial period of time.

The closest in technical essence and the achieved result is a foaming agent, comprising the following components, wt.%:

secondary sodium alkyl sulfates fractions C ₁₀ -C ₁₆ 10 ÷ 26 higher fatty alcohols fraction C ₁₂ -C ₁₆ 0.1 ÷ 5.0 urea 1,0 ÷ 8,0 butanol 0.5 ÷ 5.5 CEP (vat residues of organic synthesis) 0.5 ÷ 10.0 glycerol 0.5 ÷ 5.5 plasticizer 0.2 ÷ 8.5 setting and hardening accelerator 0.5 ÷ 6.0 water up to 100

(Patent No. 2150447, bull. No. 16, 06/10/2000)

The disadvantage of this technical solution is the increased water separation in the initial period of preparation of the foam concrete test (34%), low resistance to liquid leakage (syneresis), as well as the inaccessibility of the COO component (bottoms of the organic synthesis of N-vinylpyrrolidone, 1,4butanediol, polyvinylpyrrolidone, γ- butyrolactone, N-methylpyrrolidone, etc.) in Russia due to the liquidation of these industries. Therefore, the organization of the production of foam concrete with the specified characteristics is not possible.

The objective of the technical solution is to obtain a stable finely dispersed foam of high density, its bearing capacity with increased syneresis time, and also to reduce the consumption of a foaming agent in order to improve the operational characteristics of foam concrete (for example, strength).

The problem is solved due to the fact that the foaming agent, including primary sodium alkyl sulfates of the C ₁₂ -C ₁₄ fraction, higher fatty alcohols of the C ₁₂ -C ₁₄ fraction, urea, butanol, glycerin, gelatin, setting and hardening accelerator, hard water softener, in the following the ratio of components, wt.%:

Primary sodium alkyl sulfates C ₁₂ -C ₁₄ 18.0-22.0 Higher fatty alcohols fraction C ₁₂ -C ₁₄ 3.0-5.5 Urea 9.0-10.0 Butanol 5.0-10.0 Glycerol 5.0-10.0 Gelatin 2.0-5.0 Setting and hardening accelerator 0.5-10.0 Hard Oxide Softener 0,0-1,0 Water up to 100.0

The foaming agent of the given composition increases the foam life time due to the introduction of gelatin (denatured collagen of connective tissues), promotes the formation of stable finely dispersed foam of high density (62 ÷ 75 g / dm ³ ), an increase in the viscosity of the films in the foam bubbles, an increase in its carrying capacity and time of syneresis ( up to 12.5 min). Used technical gelatin T-4 and T-7.

In addition, glycerin increases the multiplicity of the foam, increases the viscosity of the mixture, also contributes to the production of fine foam, actively affects the hydration processes in concrete.

Sodium nitrite, monoethanolamine (they are also corrosion inhibitors), as well as sulfates of divalent and trivalent metals can be used as an accelerator of setting and hardening. The proposed limit for the introduction of this accelerator is explained by the fact that, otherwise, the expandability is reduced.

Urea (urea) increases the resistance of the foam in the air and the fire resistance of the composition, but in large quantities reduces the plasticity of the foam concrete test.

It is recommended to use Trilon B, sodium phosphates, etc. as a softener for hard water.

The preparation technology is carried out in three stages: the preparation of foam in a foam generator, the preparation of a cement-sand mortar and the introduction of foam into a liquid concrete dough. To prepare the foam, the foam concentrate and water are dosed by volume into the mixer. The finished solution is transferred to a foam generator to obtain foam. A cement-sand mortar mixture is prepared in a concrete mixer. Then the foam is fed there and mixed for 3-5 minutes. Further, by means of a flexible sleeve, it is transported into molds or formwork.

An example of a specific implementation:

Portland cement grade 500 in an amount of 800 g is mixed with 950 g of quartz sand in a dry state, then water - 380 g is added and mixed until a homogeneous mass (dough) is obtained. At the same time, foam is obtained in the foam generator by loading a mixture of 532 g of water and 14 g of a foaming agent of the composition (option No. 4 of table 1), wt.%:

Primary sodium alkyl sulfates C ₁₂ -C ₁₄ 21.0 Higher fatty alcohols fraction C ₁₂ -C ₁₄ 3.0 Urea 9.0 Butanol 6.0 Glycerol 9.0 Gelatin 5,0 Setting and hardening accelerator 6.0 Hard water softener 0.5 Water 40.5

Then the resulting foam is thoroughly mixed with cement-sand dough for 5 minutes and poured into molds 10 × 10 × 10 cm and after exposure for 16 hours, steamed at 80 ° C for 8 hours. Then cooled to room temperature and incubated for 4 hours at 20 ± 5 ° C. Next, determine the characteristics of the foam after 4 hours and 28 days.

Examples of the compositions of the foaming agents are shown in table 1, the characteristics of the properties of the foam are shown in table 2. The results of testing the foam blocks for compressive strength are presented in table 3.

Table 2. Characteristics of foam properties The composition of the foaming agent Foam ratio The density of the foam, g / DM ³ Syneresis (time of the first drop of liquid from the foam), min Water separation after 1 hour,% one 16,0 62.5 6.7 30,0 2 16.6 60.3 7.5 30,2 3 15.6 64.0 6.5 31,0 four 14,4 74.7 12.0 22.3 5 13.5 74.0 8.0 25.0 6 15.9 63.0 9.0 25.0 7 13,4 75.0 12.5 22.0 8 16,4 61.0 8.0 31,0 9 15.9 62.0 8.0 30,0 10 16,2 61.8 8.5 30,0 prototype 21,2 47.0 5.2 34.0 According to the norms. those. doc for low foam No more than 20.0 60-80 Not less than 8.0 No more than 50.0

Table 3. Characteristics of foam blocks Characteristics of foam concrete Foam concrete 800-900 kg / m ³ using a foaming agent Famous (prototype) Proposed one 2 3 four 5 6 7 8 The composition of the foam on 1 m ³ : Portland cement, kg 420 410 420 420 420 410 420 400 410 Quartz sand, kg 420 200 180 180 180 150 160 160 150 Foaming agent (≤2% aqueous solution), l fifty 60 57 52 fifty 49 47 45 40 Water, l 145 150 160 160 160 160 150 160 160 The compressive strength 4 hours after steaming, MPa 3.8 3.8 3.9 3.9 3.9 3.8 3.9 3.6 3.6 The same after 28 days 5.1 5.3 5.5 5.7 6 5.8 6 5.8 6

When using a foaming agent of the specified composition, the manufacturing process of foam concrete becomes more technologically advanced. The time of allocation of the first drop of liquid from the foam increases to 8 ÷ 12 minutes (according to the known 5.2 minutes), the foam density increases to 60 ÷ 75 g / dm ³ (according to the prototype 47 g / dm ³ ). By increasing the time of syneresis increases the time interval for performing technological operations. In addition, the presence of gelatin in the composition stabilizes the foam and does not allow it to settle during the setting and steaming.

The multiplicity of the foam on the proposed foaming agent can be adjusted using its dosage in the cement composition. It has been experimentally proved that the lowest concentration of foaming agent ≤2% provides an increase in the strength of foam concrete. Therefore, in the proposed technical solution, the calculation according to the amount of foaming agent introduced is performed based on a concentration of ≤2%.

The uniqueness of the foam obtained on the basis of the proposed composition consists in a stable microporous structure, and also in that it is able to maintain porosity in a mixture with cement-sand dough until it hardens without changing the volume.

Foam blocks obtained using the proposed blowing agent, have high heat-insulating properties, due to the uniform distribution of pores of the same size throughout the array. Pores are almost 100% closed, that is, water does not penetrate into the pores. The strength of foam blocks is at the level of world standards and after 28 days is 5.5 ÷ 6.0 MPa.

Claims (3)

1. Foaming agent for foam concrete, including alkyl sulfates, higher fatty alcohols, butanol, glycerin, urea, an accelerator setting and hardening, water, characterized in that it additionally contains softener hard water and gelatin, and as alkyl sulfates use primary alkyl sulfates of fraction C ₁₂ -C ₁₄ in the following ratio, wt.%:
primary sodium alkyl sulphates C ₁₂ -C ₁₄ 18.0-22.0 higher fatty alcohols fraction C ₁₂ -C ₁₄ 3.0-5.5 urea 9.0-10.0 butanol 5.0-10.0 glycerol 5.0-10.0 gelatin 2.0-5.0 setting and hardening accelerator 0.5-10.0 hard water softener 0,0-1,0 water up to 100.0 2. Foaming agent for foam concrete according to claim 1, characterized in that the technical gelatin T-4 and T-7 are used. 3. The foaming agent for foam concrete according to claim 1, characterized in that it contains Trilon B or sodium phosphates as a softener.