RU2394007C2 - Dry mixture for making cellular foamed fibre reinforced concrete - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to building materials and can be used in making cellular non-autoclave foamed concrete, as well as for making pieces and monoliths. The dry mixture for making cellular foamed fibre reinforced concrete contains the following in wt %: portland cement 20-75, mineral filler 7-75, microsilica 0-6, superplasticiser based on sodium salts of products of condensation of naphthalene sulphonic acid and formaldehyde 0.1-2.5, modifying additive consisting of a combination of aluminosilicate microspheres and one or more multilayered carbon nanotubes in ratio of 1:10 0.1 - 5, foaming agent 0.002-0.45, polypropylene fibre up to 1.5 kg per 1 m³ of the dry mixture.

EFFECT: simple manufacturing technology, improved physical and mechanical characteristics: frost resistance, resistance to different types of emissions, including radiation.

2 ex, 1 tbl

Description

The present invention relates to the field of building materials and can be used in the manufacture of non-autoclaved aerated concrete, as well as for the manufacture of piece goods and monoliths.

The well-known "Raw mix and method of preparation of vibration-expanded gas-ash concrete", patent No. 2281267, IPC С04В 38/00, decl. 2004.12.20, publ. 2006.08.10.

This mixture contains, wt.%:

Portland cement - 9.7-23.3;

ash - ablation of CHPP - 7 of Bratsk, obtained by burning

brown coals of KATEK, - 43.2-54.8;

building plaster - 1.9-2;

Detergent "Taiga" - 0.21-0.2;

aluminum powder - 0.06-0.07;

water is the rest.

Gas and ash concrete is prepared as follows: this mixture is placed in a mold, the mold is mounted on a vibrating plate, vibrated at a frequency of 50-100 Hz, and the mixture is expanded at the same time. Then the products are kept in the molds for 2-3 hours, cut off from them a "hump", after which the mold is placed in a heat-moisture treatment chamber with an isothermal exposure temperature of 95 ° C.

The disadvantages of the known mixture include the high energy intensity of the process (autoclave, vibrating platform), its duration, the impossibility of producing the mixture at the construction site, the presence of Taiga detergent with flavoring and bleach in the mixture, which also leads to an increase in the cost of the obtained asphalt concrete.

The well-known "Method for the preparation of aerated gas-ash concrete" according to the patent of the Russian Federation No. 2284979, IPC С04В 38/00, decl. 2007.08.10.

According to the description of the patent, the raw mixture includes, wt.%:

Portland cement - 9.7-23.3;

fly ash - 43.2-54.8;

gypsum building - 1.9-2;

Detergent "Taiga" - 0.16-0.23;

aluminum powder - 0.06-0.07;

water is the rest.

A method of preparing this mixture includes: preparing a raw mixture, its molding and heat and moisture treatment. The latter is carried out in an autoclave. The total duration of autoclave processing alone is from 11.2 to 14.5 hours.

The disadvantages of the above method as well as in the first case include: high energy intensity and cost of the process, its duration, the inability to produce and use gas and ash concrete at the construction site.

The well-known "Dry mixture for the preparation of non-autoclaved aerated concrete and method for its production", RF patent No. 2304127, IPC SB04/02, decl. 2006.03.07, publ. 2007.08.10.

This mixture contains the following components: Portland cement in an amount of 40.1-45.8 (wt.%), Quicklime in an amount of 8.1-9.2, ground sand as a mineral filler (41.3-48.0), aluminum powder as a blowing agent (0.210-0.214) and textile cord in an amount of 3.5-8.5 wt.%.

The disadvantages of the known mixture include the complexity of the process, expressed in the need for grinding sand, as well as in the need for twice accurate dosing of the components and double mixing, the presence of quicklime as a component, the extinction of which, as a rule, is uneven. The disadvantages include the impossibility of producing the mixture at the construction site.

Also known is the "Method of production and composition of a mixture of non-autoclaved aerated concrete" according to the patent of the Russian Federation No. 2243189, IPC SB04/02, decl. 2003.07.30, publ. 2004.12.27.

The mixture for the production of non-autoclaved aerated concrete contains cement, a silica component in the form of TPP ash or fine sand, gypsum, aluminum powder as a blowing agent, a plasticizer, an activating additive - soda sulfate waste from the production of alumina or another product, in which sodium sulfate predominates, and water, in the following ratio of components, wt.%:

cement - 48-52;

siliceous component (ash TPP or fine sand) - 10-14;

water - 35-37.5;

a gasifier (aluminum powder or paste) - 0.04-0.06;

building plaster - 1.2-1.4;

activating additive - 1.2-1.4;

plasticizer - 0.25-0.35.

The disadvantages of the known mixture include: a large amount of cement, as well as the presence of gypsum in the mixture, which leads to early "setting" of the mixture and the loss of some strength of aerated concrete at the end of the process.

The closest in composition to the proposed raw material mixture is "Porobeton", which is described in RF patent No. 2297993, IPC С04В 38/00, decl. 08/29/2005, publ. 04/27/2007.

Porous concrete obtained by curing the raw material mixture, includes two foaming agents, aluminum powder, silica fume, water and a fibrous aggregate in the following components, wt.%:

Portland cement - 44-83.3;

silica fume - 9-0;

natural sand - 0-30;

PPC - 0.7-1.5;

fibrous aggregate - 7-10;

water - up to W / T 0.32-0.53.

As a mixer using a turbulent mixer "Turbo-0.25" with the turbine speed per minute 800-1000.

The disadvantages of the known mixture include the complexity of the process, the need for special equipment (turbulent mixers of a certain brand with mixers, foaming agents, etc.), the need for an independent search and purchase of the necessary ingredients, the complexity of the production of concrete directly at the construction site.

The main objective of the invention is to simplify the manufacturing technology of cellular gas-fiber concrete, providing the possibility of manufacturing and using concrete at the construction site. The associated goal is to improve the physical and mechanical characteristics, such as frost resistance, resistance to various kinds of radiation, including radiation.

This goal is achieved in that the dry mixture for the production of cellular gas-reinforced concrete, including Portland cement, mineral filler, silica fume, polypropylene fiber and a blowing agent, additionally contains a superplasticizer based on sodium salts of the condensation products of naphthalenesulfonic acid and formaldehyde and a modifying additive consisting of a combination of alumina microspheres and or multilayer carbon nanotubes in a ratio of 1:10, with the following ratio of components:

Portland cement 20-75 Mineral filler 7-75 Silica fume 0-6 Specified Superplasticizer 0.1-2.5 Specified Modifier 0.1-5 Blowing agent 0.002-0.45 Polypropylene fiber up to 1.5 kg per 1 m ³

The use of a modifying additive, which contains carbon nanotubes and aluminosilicate microspheres, can significantly increase the strength of the material. These components, located on the surfaces of the filler fragments, in a polarized state, directionally affect the process of crystalline hydrate formation, while forming fibrillar microstructures of a multi-micron order. The consequence of this process is a significant hardening of non-autoclaved aerated concrete, as well as the acceleration of its hardening.

By optimizing the concentration of carbon nanotubes in an aqueous colloid, it was possible to increase almost all the indicators (strength, frost resistance, thermal conductivity) presented by GOST for cellular aerated concrete by 25-50%, to strengthen its water-repellent properties.

In addition, with the introduction of the modifying additive, cellular concrete has acquired the ability to counteract high-frequency radiation and radiation.

The modifying additive consists of a combination of aluminosilicate microspheres of the MS 100-500 brand and single or multilayer carbon nanotubes obtained by gas-phase chemical deposition (catalytic pyrolysis-CVD) of gaseous hydrocarbons on catalysts (Ni / Mg) at atmospheric pressure with the following characteristics: outer diameter - 10-60 nm, inner diameter 10-20 nm, length 2 and more nm in a ratio of 1:10.

Regarding the remaining components of the raw mix:

Portland cement must comply with the requirements of SN 277-80 and GOST 10178 for Portland cement without mineral additives (PC-DO) and Portland cement with active mineral additives (PC - D5, PC - D20) of grade not less than 400.

The following are used as mineral filler (mineral additives): fly ash from burning coal, ash and slag mixtures, silica sand, limestone, mixtures consisting of two or more of these additives. At the same time, mineral additives must meet the requirements of current standards or specifications:

quartz sands - GOST 8736 and SN - 277-80;

fly ash - GOST 25818;

slags of ferrous and non-ferrous metallurgy - GOST 5578;

carbonate rocks - GOST 15050-936, STB 1417-2003, GOST 16557-78, TU RB 00294585.003-97.

Silica fume - an active additive of the MKU-85 brand, waste from metallurgical production.

Pore former - an active additive that forms pores, for example, aluminum powder of the PAP grades, aluminum paste, bleach, hydrogen peroxide, etc.

Superplasticizer is an additive based on sodium salts of condensation products of naphthalenesulfonic acid and formaldehyde.

The dry mixture is prepared as follows.

Example 1. Portland cement, then silica fume, superplasticizer, a modifying additive and a blowing agent are fed to the mixer in a predetermined proportion, after 5 minutes of mixing, polypropylene fiber and filler are added, then at least 10 minutes are mixed and the prepared mixture is fed into a mechanical activator.

Example 2. Portland cement, then silica fume, superplasticizer, modifying additive, blowing agent and polypropylene fiber are fed into the mixer in a predetermined proportion, all mixed for at least 10 minutes and the prepared mixture and filler are fed into the mechanical activator in a predetermined proportion.

The table below shows the composition of the dry mix for the production of cellular gas-fiber concrete.

Table The components of the dry mixture, in wt.%: one 2 3 Portland cement twenty fifty 75 Mineral filler 75 * 41.3 ** 11.05 *** Silica fume 2 four 6 Superplasticizer 0.1 1,5 2.5 Modifying additive 2,8 3 5 Blowing agent 0.1 * 0.2 ** 0.45 *** Total: one hundred% one hundred% one hundred% Polypropylene fiber, kg per 1 m ³ dry mix one 1,2 1,5 * - as a mineral filler use a mixture consisting of ash - fly ash from the burning of coal, slag and silica sand
** - as a mineral filler use a mixture consisting of ash - fly ash from the burning of coal and silica sand
*** - limestone is used as a mineral filler
* - aluminum powder is used as a blowing agent
** - bleach is used as a blowing agent
*** - hydrogen peroxide is used as a blowing agent

Claims (1)

A dry mixture for the production of cellular gas-fiber concrete, including Portland cement, a mineral filler, silica fume, polypropylene fiber and a blowing agent, characterized in that it additionally contains a superplasticizer based on sodium salts of the condensation products of naphthalene sulfonic acid and formaldehyde and a modifying additive consisting of a combination of alumina or microspheres multilayer carbon nanotubes in a ratio of 1:10 with the following ratio of components:
Portland cement 20-75 mineral filler 7-75 silica fume 0-6 specified superplasticizer 0.1-2.5 specified modifier 0.1-5 blowing agent 0.002-0.45 polypropylene fiber up to 1.5 kg per 1 m ^{3 of} dry mix