RU2719804C1 - Crude mixture for production of non-autoclave foam concrete - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to the industry of construction materials, specifically to crude mixtures for production of non-autoclave foam concrete, and can be used for production of heat-insulating and structural-heat-insulating gas concrete. Raw mixture for production of non-autoclave foam concrete contains the following, wt. %: binding substance - calcium slaked lime 12–21 and Portland cement 12–21, stone and marble limestone waste deposits of Crimean deposit 24–42, aluminium powder 0.05–0.07, water balance.

EFFECT: technical result is high strength and heat-insulating properties of articles made from non-autoclave foam concrete of low density.

1 cl, 4 ex

Description

The technical solution relates to the building materials industry, namely, raw material mixtures for the production of non-autoclaved aerated concrete and can be used for the production of heat-insulating and structural-heat-insulating aerated concrete.

The composition of the raw material mixture for producing aerated concrete is known (RU No. 2255073, class C04B 38/02, June 27, 2005), in which Portland cement is used as a binder, sand is used as a filler, gas-forming agent in the form of aluminum powder, caustic soda as a reaction accelerator gas formation and water in the following ratio of components, wt. %:

- Portland cement - 15-50;

- sand-31-42;

- aluminum powder - 0.10-1.0;

- caustic soda - 0.05-0.45;

- water - the rest.

A disadvantage of the known composition is the increased consumption of the most expensive component of the raw material mixture - aluminum powder, which entails an increase in the cost of aerated concrete. In addition, the use of caustic soda in the composition of the raw material mixture may entail the appearance of such a negative phenomenon as efflorescence on finished products. Also, the use of natural dispersion in sand in this composition can cause the phenomenon of sedimentation in the manufacture and laying of aerated concrete mixture, which leads to heterogeneity of the structure of aerated concrete, an increase in the thickness of partitions, coalescence of pores, which entails sedimentation of the mixture, an increase in average density and a decrease in the strength of finished products.

The closest in technical essence and technical result that is achieved, and selected as a prototype, is the patent "Raw mix for the production of cellular aerated concrete, hardening in a carbon dioxide environment" (RU No. 151756, class С04В 14/02, С04В 14/36, 10.04 .2015). The composition of the raw mix includes hydrated calcium lime, waste stone sawing and processing limestone-shell rock, aluminum powder and water in the following ratio, wt. %:

- slaked calcium lime - 18-27;

- waste of stone sawing and limestone-shell rock processing - 22-33;

- aluminum powder - 0.07-0.2;

- water - the rest.

The disadvantages of the prototype are:

- increased consumption of the most expensive component of the raw mix of aluminum powder, which entails an increase in the cost of aerated concrete;

- the use of a large amount of slaked lime, which entails an increase in water-solid ratio and a decrease in the future, the strength of the finished product due to an increase in the degree of manifestation of shrinkage phenomena in the drying process, increases the cost of aerated concrete;

- the proposed composition allows to obtain exclusively thermal insulation material with low strength indicators.

The objective of the invention is to develop a raw material mixture for the production of non-autoclave heat-insulating and structural-heat-insulating aerated concrete, which has improved physical and mechanical characteristics, gaining strength due to hydration and carbonate hardening, with the achievement of the technical result is to increase the strength and thermal insulation properties of products from non-autoclave aerated concrete of low density by lime-cement binder.

The problem is solved in that in the raw material mixture for the production of non-autoclaved aerated concrete, which contains aggregate, a mixed binder, a gasifier and water, the fillers use stone sawing waste and processing marble-like limestone of the Crimean field, and Portland cement and slaked calcium lime as a mixed binder. The ratio of raw materials, wt. %:

- slaked calcium lime - 12-21;

- Portland cement - 12-21;

- waste of stone sawing and processing marble-like limestone - 24-42;

- aluminum powder - 0.05-0.07;

- water - the rest.

Between the totality of the essential features of a utility model and the technical result, there is the following causal relationship.

In the inventive raw material mixture, Portland cement and slaked calcium lime are used as a binder in a ratio of 1: 1 in an amount of 24-42% of the total weight of the mixture, which is the basis for hydration and carbonate hardening under conditions of heat and moisture treatment and an increased concentration of carbon dioxide. This contributes to the formation of the maximum number of crystalline tumors and increase the strength of products.

The introduction of a binder in an amount of less than 24% is not enough to form a spatial crystalline structure, which would provide the necessary physical and mechanical characteristics of the products. The coefficient of expansion of the aerated concrete mass also decreases and a mixture precipitation is observed.

The introduction of more than 42% of a mixed binder into the composition entails the formation of a torn cellular structure with irregular pores due to an increase in the rate of gas formation. The water-solid ratio increases, which leads to the formation of a large number of microcracks and reduces the physical and mechanical characteristics of the finished product. Also, the introduction of a large amount of astringent is impractical from an economic point of view.

Using as a filler waste stone-cutting and processing marble-like limestones with a specific surface of 2500-3500 cm ² / g in an amount of 24-42% of the total weight of the mixture allows you to create additional centers of crystallization in the limestone-cement matrix, as well as improve the accretion contacts on the border "aggregate - binder "due to the similar structure of the aggregate substance with the product of lime carbonization - secondary calcium carbonate.

The grinding of stone-cutting limestone stone-cutting waste is less expensive than quartz sand, because this material does not have significant strength compared to the siliceous component used as a filler in traditional raw material mixtures for the production of aerated concrete. Milling of sawmill waste to a specific surface of 2500-3500 cm ² / g takes 15-30 minutes.

The proposed aggregate is industrial waste and is mainly disposed of in dumps, so its use is a priority in the production of non-autoclaved heat-insulating and structural-heat-insulating cellular concrete.

The raw material mixture is prepared as follows.

Dose components in the amount, wt. %:

- slaked calcium lime -12-21;

- Portland cement - 12-21;

- waste of stone sawing and processing marble-like limestone - 24-42;

Water is poured into the mixer to the optimum mobility of the mixture, due to the standard Suttard cone spread (330-350 mm) (amount of water 29-38% of the total weight of the mixture), and a gasifier is added - 0.05-0.07% of the total weight of the mixture .

Mix thoroughly.

Next, a binder and aggregate are added to the mixer from the dispenser.

The resulting raw material mixture is thoroughly mixed and poured into molds, which, after preliminary exposure and setting the mixture, are sent to the stripping and sawing station. Further, aerated concrete is sent to the chamber of heat-moisture treatment, then to the carbonization chamber. As a source of carbon dioxide, you can use the gases of lime kilns and thermal power plants. These conditions provide hydration and carbonate hardening of aerated concrete.

In the preparation of the raw material mixture, waste from stone sawing and processing of marble-like limestone from a deposit located in s. Marble. Chemical analysis of the aggregate showed the presence of the following compounds,%: SiO ₂ - 1.9; Al ₂ O ₃ - 1.57; Fe ₂ O ₃ - 0.68; MgO - 2.54; SO ₃ 0.67; CaO - 48.08.

The claimed raw material mixture is characterized by increased strength (3.5 MPa) and corresponding density (500-600 g / cm ³ ) with low thermal conductivity (0.09-0.13 W / (mK)) for the production of non-autoclaved aerated concrete.

For comparison: according to the prototype, the physical and mechanical characteristics of porous concrete: compressive strength - 2.5 MPa; average density - 700 kg / m3; thermal conductivity coefficient - 0.16-0.18 W / (mK).

Example 1

The ratio of components in the raw mix, wt. %: slaked calcium lime - 12; Portland cement - 12; stone-cutting waste and processing of marble-like limestone of the Crimean deposit - 42; a gasifier (aluminum powder) of the total mass of the mixture is 0.07. The amount of water - the rest, to the optimum mobility of the mixture, due to the standard spread of the Suttard cone (330-350 mm).

Physico-mechanical characteristics of the obtained porous concrete: compressive strength - 2.5 MPa; average density - 500 kg / m ³ ; thermal conductivity coefficient - 0.089-0.095 W / (mK).

Example 2

The ratio of components in the raw mix, wt. %: slaked calcium lime - 21; Portland cement - 21; waste of stone sawing and processing marble-like limestone of the Crimean deposit - 24; pore former (aluminum powder) of the total mass of the mixture is 0.05. The amount of water - the rest, to the optimum mobility of the mixture, due to the standard spread of the Suttard cone (330-350 mm).

Physico-mechanical characteristics of the obtained aerated concrete: compressive strength - 3.5 MPa; average density - 600 kg / m ³ ; thermal conductivity coefficient - 0.10-0.12 W / (mK).

Example 3

The ratio of components in the raw mix, wt. %: slaked calcium lime -10; Portland cement - 10; waste of stone sawing and processing of marble-like limestone of the Crimean deposit - 46; pore former (aluminum powder) of the total mass of the mixture is 0.09. The amount of water - the rest, to the optimum mobility of the mixture, due to the standard spread of the Suttard cone (330-350 mm).

Physico-mechanical characteristics of the obtained aerated concrete: compressive strength - 1.0 MPa; average density - 650 kg / m ³ ; thermal conductivity coefficient - 0.12-0.13 W / (mK).

Example 4

The ratio of components in the raw mix, wt. %: slaked calcium lime - 25; Portland cement - 25; stone-cutting waste and processing of marble-like limestone of the Crimean deposit - 16; pore former (aluminum powder) of the total mixture weight is 0.08. The amount of water is up to the optimal mobility of the mixture, due to the standard spread of the Suttard cone (330-350 mm).

Physico-mechanical characteristics of the obtained aerated concrete: compressive strength - 2.5 MPa; average density - 600 kg / m ³ ; thermal conductivity coefficient - 0.10-0.11 W / (mK).

The advantages of the mixture include the possibility of obtaining heat-insulating and structural-heat-insulating aerated concrete, which is gaining strength due to both hydration and carbonate hardening. This ensures the reduction of carbon dioxide emissions into the atmosphere by its sequestration into finished products. When this mixture is used in non-autoclaved aerated concrete production technology, the cost of the finished product is reduced due to the use of limestone mining and stone sawing waste instead of expensive quartz sand, the use of stone sawing waste and processing of marble-like limestone of the Crimean field ensures waste disposal in Crimea.

Claims (2)

Raw mix for the production of non-autoclaved aerated concrete, including aggregate, mixed binder, blowing agent and water, characterized in that the filler uses waste stone sawing marble-like limestones of the Crimean deposits, as a binder - slaked calcium lime and Portland cement in the following ratio of raw materials, wt .%: slaked calcium lime 12-21 Portland cement 12-21 stone cutting and marbled limestone processing waste 24 - 42 aluminum powder 0.05 - 0.07 water rest