RU2392245C1 - Dry mortar for preparation of cellular concrete - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: dry mortar for preparation of cellular concrete on the basis of gypsum contains the following components, wt %: gypsum binder 60.0-95.0, modifying additive 4.99-37.0, foamer and/or gasifier 0.01-3.0. At the same time modifying additive has specific surface of 1000-10000 m²/kg, average size of particles of not more than 50 micrometre, hydraulic activity of at least 1 mg/g and contains the following components, wt %: hydraulic binder 50.0-90.0, active mineral component 9.9-45.0, plasticising additive - 0.1-5.0, controller of setting and hardening times 0.1 over 100, stabiliser 1.0 over 100.

EFFECT: simplified production-process cycle of cellular concrete preparation and products from it with simultaneous improvement of physical and mechanical properties.

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Description

The invention relates to the production of building materials, namely, the preparation of dry mixtures with the addition of foaming and / or gas-forming agents, and can be used in construction - monolithic housing construction for the manufacture of light, durable and heat-insulating wall structures and products from materials based on it, and in road construction as a base layer under the road surface.

A known raw material mixture for the preparation of cellular concrete based on cement (slag Portland cement M400) as a binder, also containing silica sand as a siliceous component, C-3 superplasticizer, ground quicklime, rosin, a 27-28% solution of triethanolamine salt of alkyl sulfates, liquid glass with a siliceous module 2.8 with a density of 1300 kg / m ³ , gypsum building and tap water / RU 2064913, class. С04В 38/02 from 08/10/96 /.

The introduction of gypsum does not significantly reduce the shrinkage of cellular concrete, but it has a long formwork strength and, as a result, the difference in density and strength of the upper and lower layers. In addition, the need to use autoclave technology complicates the manufacturing process of aerated concrete, leads to high energy time costs for production and low technical and economic indicators, such as cost.

A known raw material mixture for the preparation of cellular concrete based on cement or a mixture of cement with gypsum and / or lime, where Portland cement, slag Portland cement, pozzolanic cement or a mixture thereof is used as a binder. As a filler, it uses sand, ash, slag, finely ground ceramic or silicate brick, a foaming agent and / or aluminum powder, an additive (1 ... 10 wt.%) / RU 2187485, cl. С04В 38/02 from 08.20.2002 /.

The resulting cellular concrete solves the problem of uniformity in height of pouring while improving other indicators - reducing the cycle of manufacturing the raw mixture to autoclave hardening, lack of shrinkage, however, the use of autoclave technology complicates the manufacturing process of cellular concrete, leads to high energy costs for concrete production and low technical economic performance.

Also known is a raw material mixture for the production of cellular concrete based on gypsum, containing one part of gypsum, 0.1-0.15 parts of lime, 0.03-0.05 parts of cement (obtained by grinding red brick or burning clay at 700-800 ° C followed by grinding), 0.8-0.9 water and a foaming agent / G.V. Nagibin, P.F. Pavlov, M.A. Ellern. Technology of heat-insulating and gypsum materials. 2nd edition, revised and supplemented. M.: Higher School, 1973, pp. 136-137 /.

The closest technical solution is lightweight concrete based on composite gypsum, which is a mixture of gypsum binder with an organo-mineral modifier - OMM and a blowing agent. OMM consists of Portland cement of any kind, siliceous additives, superplasticizers, setting and hardening regulators, polymer additives and thickeners. As a siliceous additive in OMM, fly ash, ceramic dust, ceramic waste products, glass break, fine quartz sand, silica fume, silica gel, spent silica gel and similar materials are used, and S-3 superplasticizer, technical lignosulfonates, etc. . / U.B. Bazhenov et al. Dry mortar technology. M.: DIA, 2003, pp. 21-27 /.

The use of gypsum as a binder improves a number of characteristics, such as shortening the production and technological cycle, reducing energy consumption, improving physical and mechanical properties - compressive strength occurs after two hours, the time to reach formwork strength is reduced several times, the cost of the resulting product is reduced, while no autoclave technology is used. However, after exposure, the products are dried in a drying chamber at a temperature of 40-50 ° C for 16 hours. In addition, the resulting gypsum-based cellular concrete products have reduced strength and insufficient frost resistance and water resistance.

The technical task of this invention is to simplify the production cycle of the preparation of cellular concrete and products from it, while improving physical and mechanical properties.

The technical problem and the industrial applicability of the present invention are ensured by the fact that the dry mortar for the preparation of cellular concrete based on gypsum binder contains a gypsum binder, a modifying additive and a foaming agent and / or blowing agent in the following ratio, wt.%:

gypsum binder 60.0-95.0 modifying additive 4.99-37.0 foaming agent and / or blowing agent 0.01-3.0

wherein the modifying additive has a specific surface area of 1000-10000 m ² / kg, an average particle size of not more than 50 μm, the hydraulic activity of CaO at the age of 28 days at a temperature of 20 ° C of at least 1 mg / g and contains, wt.%:

hydraulic binder 50.0-90.0 active mineral component 9.9-45.0 plasticizer 0.1-5.0 setting and setting times 0.1 over 100% stabilizer 1.0 in excess of 100%.

Moreover, as a gypsum binder, semi-aquatic gypsum or anhydrite is used, or a mixture thereof in any proportion.

A hydraulic binder contains one of the following components or mixed in any proportion: Portland cement of any kind, white cement, non-ferrous cement, alumina cement, hydraulic lime.

The active mineral component contains one of the following components or mixed in any proportion: fly ash, rice husk ash, buckwheat ash ash, TPP ash and slag, blast furnace slag, ceramic dust, ceramic waste, metakaolin, fine quartz sand, silica fume, pumice, glass break, silica gel, tuff, diatomaceous earth, soot, aerosil, waste products from the production of aluminum compounds — epoxy residues containing clay particles and amorphous silica.

Known components based on natural or synthetic raw materials are used as a foaming agent, for example, a “Pioneer” brand foaming agent, and hydrogen peroxide, aluminum powder and others as a blowing agent.

The regulator of the setting time and hardening in the claimed invention can be a gypsum hardening inhibitor - natural tartaric acid, citric acid, malic acid, casein glue or gypsum hardening accelerator - two-water gypsum, sodium carbonate, copper sulfate, ferrous sulfate.

As a stabilizer, hydroxyethyl cellulose, hydroxypropyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxymethyl propyl cellulose are used.

The plasticizing additive is presented in the form of a superplasticizer containing one of the following or mixed in any proportion: plasticizers based on sulfonated melamine formaldehyde compounds, plasticizers based on sulfonated naphthalene formaldehyde compounds, plasticizers based on modified lignosulfonates or plasticizers based on water-soluble carboxylate polymers. As a plasticizing additive, which is a mixture of the above plasticizers, for example, a mixture containing, wt.%: A plasticizer based on sulfonated naphthalene formaldehyde compounds 70, a plasticizer based on modified lignosulfonates 30, or a mixture containing, wt.%: Plasticizer based on sulfonated melamine formaldehyde compounds 90, a plasticizer based on water-soluble carboxylate polymers 10, or a mixture containing, wt.%: a plasticizer based on modified lignosulfon onat 90, a plasticizer based on water-soluble carboxylate polymers 10, or a mixture containing, wt.%: a plasticizer based on modified lignosulfonates 60, a plasticizer based on water-soluble carboxylate polymers 40.

With this value, the specific surface area of the additive increases significantly from 1000 to 10,000 m ² / kg. The modifying additive has indicators that satisfy the following requirements - with a specific surface area of at least 1000 m ² / kg, with an average particle size of not more than 50 μm and a CaO hydraulic activity of 28 days at a temperature of 20 ° C of at least 1 mg / g.

The preparation of aerated concrete on the basis of a dry construction mixture containing a gypsum binder, a modifying additive and a foaming agent and / or gasifier is carried out according to any known scheme, for example using barotechnology, that is, by mixing the mixture under high pressure, or according to the classical scheme, or using a foam generator, while the dry components are mixed in a conventional mixer, and the production of additives for the modification of gypsum binders, mortars and concrete based on them includes two of these a. First, the dosed components of the additive are pre-mixed in a forced action mixer. At the second stage, the resulting mixture is fed into a mixer-activator of a centrifugal-shock type of continuous action, for example, SCS-450.

To illustrate the production of aerated concrete based on a dry building mixture containing a gypsum binder, a modifying additive and a foaming agent and / or gasifier, examples of specific performance are given below.

Example 1

For experimental verification of the claimed composition, the following raw mixture of ingredients was prepared (% by weight):

1. gypsum binder - semi-aquatic gypsum 72 2. modifying additive 27

wherein the addition of the following composition (% by weight):

- hydraulic binder - Portland cement 87.9 - active mineral component - silica fume 10.0 - superplasticizer - Melflux 1,0 - gypsum hardening inhibitor - natural tartaric acid 0.1 (in excess of 100%) - stabilizer - hydroxyethyl cellulose 1.0 (in excess of 100%) 3. the foaming agent - Pioneer-118 1,0.

The tests were carried out in accordance with GOST-21520-89. The test results of the samples of cellular concrete are shown in table 2. The resulting composition has improved physicomechanical characteristics - high density, high compressive strength, high tensile strength, frost resistance, high resistance to weathering.

Example 2

For experimental verification of the claimed composition, the following raw mixture of ingredients was prepared (% by weight):

1. gis binder - semi-aquatic gypsum 80.0 2. modifying additive 19.5

wherein the addition of the following composition (% by weight):

- hydraulic binder - Portland cement 87.9 - active mineral component - silica fume 10.0 - superplasticizer - C-3 1,0 - gypsum hardening inhibitor - natural tartaric acid 0.1 (in excess of 100%) - stabilizer - hydroxypropyl cellulose 1.0 (over 100%) 3. gasifier - aluminum powder grade PAP-31 0.5

The tests were carried out in accordance with GOST-21520-89. The test results of the samples of cellular concrete are shown in table 2. The resulting cellular concrete has medium strength and average bulk density, has improved physical and mechanical characteristics - good compressive strength, frost resistance and good resistance to weathering.

Example 3

For experimental verification of the claimed composition, the following raw mixture was prepared (% by weight):

1. gypsum binder - semi-aquatic gypsum 90.0 2. modifying additive 7.0

wherein the addition of the following composition (% by weight):

- hydraulic binder - Portland cement 58.0 - active mineral component - glass break (up to 3 mm) 40,0 - superplasticizer - LST 0.9 - gypsum hardening inhibitor - natural tartaric acid 0.1 (in excess of 100%) - stabilizer - hydroxyethyl cellulose 1.0 (over 100%) 3. foaming agent and blowing agent - Pioneer-118 and PAP-31 with a weight ratio of 1: 1 3.0.

The tests were carried out in accordance with GOST-21520-89. The test results of the samples of cellular concrete are shown in table 2.

Table 1 shows the comparative characteristics of the known and proposed cellular concrete. As can be seen from the example, despite the fact that only 7% of the additive was used to modify gypsum binders, the lightweight concrete obtained has high mobility, frost resistance and high resistance to weathering, while the specific surface area of the additive is 600 m ² / kg.

Thus, the proposed invention provides the achievement of the task of simplifying and accelerating the production and technological cycle of obtaining cellular concrete and products from it several times with simultaneous improvement of physical and mechanical properties - high compressive strength, high tensile strength, frost resistance, high resistance to weathering . As a result, energy and time costs and the cost of the resulting cellular concrete products were significantly reduced.

Table 1 Options Suggested composition Example 1 Example 2 Example 3 Prototype 1. Compression strength, MPa: 28 days 52 55 35 thirty 2. Tensile strength in bending, MPa: 28 days thirty 36 16 12 3. Setting time, min: Start thirty fifty thirty 10 The ending 60 90 60 twenty 4. Water-solid ratio 0.18 0.20 0.18 0.26 5. Frost resistance, cycles fifty 60 40 thirty 6. Softening coefficient 0.86 0.90 0.82 0.80 7. Water retention capacity,% 99 99 99 70-75 8. The mobility of the mixture Sutgard, mm After 5 min 250 250 250 200 In 10 minutes 250 250 250 150 After 15 min 250 250 250 70

table 2 Options Suggested composition Prototype Analogue Example 1 Example 2 Example 3 1. Compressive strength, MPa: 28 days 3,5 3,5 four 1.8 3 2. Setting time, min: Start thirty thirty thirty 10 240 the ending 60 60 60 twenty 480 3. Water-solid ratio 0.43 0.20 0.18 0.67 0.35 4. Frost resistance, cycles thirty thirty thirty 2 20-30 5. Softening coefficient 0.8 0.84 0.9 0.3 0.9 6. The time of formwork strength, hours 2 2 2 2 24 7. Shrinkage,% 0 0 0 0 up to 2 8. Density, kg / m top layer 600 600 600 600 500 bottom layer 600 600 600 600 700 9. The drying time of the product in the drying chamber, hours 0 0 0 16 24

Claims (1)

Dry building mix for the preparation of cellular concrete based on gypsum, characterized in that it contains a gypsum binder, a modifying additive and a foaming agent and / or blowing agent in the following ratio of components, wt.%:
gypsum binder 60.0-95.0 modifying additive 4.99-37.0 blowing agent and / or blowing agent 0.01-3.0
wherein the modifying additive has a specific surface area of 1000-10000 m ² / kg, an average particle size of not more than 50 μm, hydraulic activity of not less than 1 mg / g and contains, wt.%:
hydraulic binder 50.0-90.0 active mineral component 9.9-45.0 plasticizer 0.1-5.0 setting and setting times 0.1 over 100 stabilizer 1.0 over 100