RU2460708C1 - Composition of raw mix to manufacture nonautoclave-hardening aerated concrete - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: composition of raw mix for manufacturing of nonautoclave-hardening aerated concrete contains the following components, wt %: portland cement 35.30-49.40, limestone 2.6-2.65, aluminium powder 0.06-0.10, calcium chloride 0.18-0.25, limestone crushed down to specific surface of 300-700 m²/kg 12.40-26.50, water - balance.

EFFECT: stabilisation of a process of aerated concrete mixture aeration, improved operational characteristics of an aerated concrete, reduction of its prime cost with simplification of mixture composition.

1 ex, 2 tbl

Description

The invention relates to the production of building materials and products from cellular concrete, porous with gas, and can be used in the manufacture of products used for the construction and thermal insulation of residential, administrative and industrial buildings and structures.

The known composition of the raw material mixture for the production of aerated concrete (RU No. 2255073, class C04B 38/02, 06/27/2005), including Portland cement, sand, aluminum powder, caustic soda, mixing water, with a ratio of components, wt.%:

Portland cement 15-50 Sand 31-42 Aluminum powder 0.10-1.0 Caustic soda 0.05-0.45 Water rest

A disadvantage of the known composition is the increased consumption of the most expensive component of the raw material mixture - aluminum powder, which leads to an increase in the cost of aerated concrete. In addition, the use of natural dispersion in a known sand composition can cause sedimentation phenomena when preparing and laying aerated concrete mixture, which leads to a variotropic structure of aerated concrete, an increase in the thickness of the inter-pore wall, which negatively affects the strength characteristics, and leads to an increase in its average density.

Closest to the proposed composition is the composition of the mixture for the manufacture of autoclaved aerated concrete (RU 2209801, class C04B 38/02, 2003), including Portland cement, a suspension of aluminum powder, milk of lime, semi-aquatic gypsum in the form of a suspension in water in a ratio of 1: 1.63 ÷ 7, silica fume, calcium chloride, mixing water with a ratio of components, wt.%:

Portland cement 51-71 Aluminum powder 0.01-0.15 Lime 0.04-0.7 Semi-aquatic gypsum 0.1-0.4 Silica fume 0.6-3.5 Calcium chloride 0.5-3 Water rest

A disadvantage of the known composition is the increased consumption of Portland cement - a relatively expensive component of the raw mix, which leads to an increase in the cost of aerated concrete. The introduction of lime mortar into the composition of the aerated concrete mixture does not provide sufficient intensification of the porization process (the process begins not earlier than 10 minutes after mixing).

The objective of the invention is to develop a composition of non-autoclaved aerated concrete, which can be used in the manufacture of piece goods used for the construction and insulation of residential, administrative and industrial buildings and structures.

The technical result of the invention is the stabilization of the process of porosity of aerated concrete mixture, improving the operational characteristics of aerated concrete, reducing its cost while simplifying the composition of the mixture.

The task and the specified technical result are achieved in that the composition of the raw material mixture for the manufacture of non-autoclaved aerated concrete, including Portland cement, lime, aluminum powder, calcium chloride and water, according to the invention additionally contains limestone, ground to a specific surface of 300 ÷ 700 m ² / kg in the following the ratio of components, wt.%:

Portland cement 35.30 ÷ 49.40 Limestone 12.40 ÷ 26.50 Lime 2.60 ÷ 2.65 Aluminum powder 0.06 ÷ 0.10 Calcium chloride 0.18 ÷ 0.25 Water rest

When the content of Portland cement in non-autoclaved aerated concrete is less than 35.3%, the strength of aerated concrete is below the level acceptable by standards, and when the Portland cement content is more than 49.4%, shrinkable deformations appear in aerated concrete, leading to a decrease in strength and frost resistance.

When the lime content is less than 2.60%, sufficient alkalinity of the liquid phase and effective gas formation of the mixture are not provided, and when the lime content is more than 2.65%, the strength of aerated concrete unreasonably decreases.

When the limestone content is less than 12.4%, shrinkage deformations appear, leading to a decrease in strength and frost resistance. When the limestone content is more than 26.5%, the strength of aerated concrete is below the level acceptable by the standards. The specific surface of limestone of less than 300 m ² / kg can cause sedimentation phenomena during the preparation and laying of aerated concrete mixture, which leads to a variotropic structure of aerated concrete, an increase in the thickness of the inter-pore septum, which negatively affects the strength characteristics and leads to an increase in the average density of the material. If the specific surface of limestone is more than 700 m ² / kg, then the mobility of the aerated concrete mixture sharply decreases and the average density of aerated concrete increases.

When the content of aluminum powder is less than 0.06%, aerated concrete does not reach the specified porosity, which leads to an increased average density. When the content of aluminum powder is more than 0.10%, an excess amount of hydrogen is formed, which leads to the merging of gas bubbles and tearing them out through the surface to the outside. As a result, sediment aerated concrete mixture.

Calcium chloride improves the expansion of the aerated concrete mixture, and also helps to accelerate the hardening of aerated concrete, which allows to obtain products without heat treatment. When the content of calcium chloride is less than 0.18%, effective acceleration of the hardening of aerated concrete is not provided. When the content of calcium chloride is more than 0.25%, the hardening acceleration effect is reduced.

The composition of the raw mix for the manufacture of non-autoclaved aerated concrete is illustrated by an example.

Example 1

To obtain non-autoclaved aerated concrete, Portland cement, limestone, lime, preferably quicklime, aluminum powder, calcium chloride were used. Table 1 shows the specific compositions for the production of non-autoclaved aerated concrete.

All dry components of the mixture were weighed in the required amount and mixed. Limestone was preliminarily dried and ground to a specific surface of 300, 500 and 700 m ² / kg. The resulting mixture was placed in water at a temperature of 60 ° C and stirred for 1 min. Then, a prefabricated aluminum suspension was added to the mixture and mixed for another 1 min. The resulting aerated concrete mixture was poured into molds of 10 × 10 × 10 cm. After 3 hours exposure, the “hump” was cut. Forms were dismantled after 48 hours, after which the samples were covered with a plastic film, where they hardened at a temperature of 20 ± 2 ° C for 26 days. Subsequently, the samples were dried to constant weight and subjected to physical and mechanical tests. The test results are shown in table 2. The remaining examples of the preparation of the composition for non-autoclaved aerated concrete was carried out analogously to example 1, the data of which are presented in tables 1 and 2.

Table 1 No. p / p Formulation Examples The content of components, wt.% Cement Limestone Calcium chloride Lime Alum. powder Water one The specific surface of limestone is 300 m ² / kg 1.1 Composition No. 1 35.3 26.5 0.18 2.60 0.10 35.32 1.2 Composition No. 2 41.2 20.6 0.21 2.63 0.08 35.28 1.3 Composition No. 3 49.4 12,4 0.25 2.65 0.06 35.24 2 The specific surface of limestone is 500 m ² / kg 2.1 Composition No. 4 35.3 26.5 0.18 2.60 0.10 35.32 2.2 Composition No. 5 41.2 20.6 0.21 2.63 0.08 35.28 2.3 Composition No. 6 49.4 12,4 0.25 2.65 0.06 35.24 3 The specific surface of limestone is 700 m ² / kg 3.1 Composition No. 7 35.3 26.5 0.18 2.60 0.10 35.32 3.2 Composition No. 8 41.2 20.6 0.21 2.63 0.08 35.28 3.3 Composition No. 9 49.4 12,4 0.25 2.65 0.06 35.24

table 2 Composition number The average density, kg / m ³ The compressive strength at the age of 28 days, MPa Quality factor Composition No. 1 455 0.7 1,5 Composition No. 2 470 1,5 3.2 Composition No. 3 460 1,5 3.3 Composition No. 4 430 0.9 2.1 Composition No. 5 460 1,5 3.3 Composition No. 6 505 1.9 3.8 Composition No. 7 440 0.8 1.8 Composition number 8 465 1.7 3,7 Composition No. 9 495 1,2 2,4

The joint presence of these substances in the mixture of the proposed composition ensures the production of aerated concrete products with an average density of up to 505 kg / m ³ with a strength of up to 1.9 MPa, which exceeds the strength characteristics of aerated concrete products of a non-autoclave hardening method of known compositions, as well as those specified in GOST 25485-89 " Cellular concrete. Technical conditions. " The use of waste crushing limestone, reducing cement consumption and reducing the components of the composition (simplification), compared with the prototype, helps to reduce the cost of aerated concrete by 30%.

Claims (1)

The composition of the raw mix for the manufacture of non-autoclaved aerated concrete, including Portland cement, lime, aluminum powder, calcium chloride and water, characterized in that it additionally contains limestone, ground to a specific surface of 300-700 m ² / kg, in the following ratio, wt.% :
Portland cement 35.30-49.40 limestone 12.40-26.50 lime 2.60-2.65 aluminum powder 0.06-0.10 calcium chloride 0.18-0.25 water rest