RU2742784C1 - Method of making foam concrete, the raw mixture for making foam concrete and foam concrete - Google Patents

Abstract

FIELD: construction materials industry.

SUBSTANCE: group of inventions relates to the construction materials industry and namely to the production of cellular concrete, particularly foam concrete used for manufacturing any product, more preferably for small wall blocks of industrial premises, multi-storey and individual residential buildings. The method of producing foam concrete encompasses the following stages: supplying water, the foaming agent ”PB-Lux” and urea-formaldehyde “KF-ZH” to a foam generator for producing foam; stirring the above components in the foam generator until foam is obtained; mixing Portland cement, fine aggregate - quartz sand and water in a concrete mixer to make a homogeneous solution of the required consistency; feeding foam from the foam generator into a concrete mixer containing cement mortar and stirring the above components for 2-5 minutes until a homogeneous foam concrete mixture is obtained with the formation of a porous structure; laying the foam concrete mixture in pre-lubricated metal molds; curing and/or keeping the foam concrete mixture for a period of time under normal conditions. The components for making the foam concrete mixture are used in the following ratio: wt%: Portland cement 48.5-49.44; fine aggregate - quartz sand 19.7-20.0; the foaming agent “PB-Lux” 0.16-0.18; urea-formaldehyde “KF-ZH” 1.20-1.32; water for making foam 9.8-10.0; water for making cement mortar 19.7-20.0. The raw mixture for foam concrete was made as described above. Foam concrete was made of the raw mixture mentioned above in accordance with the above description. The group of inventions is developed in the formula subclaims.

EFFECT: improved strength and softening coefficient while the coefficient of thermal conductivity of foam concrete is reduced.

5 cl, 1 tbl

Description

The technical field to which the invention relates

The invention relates to the building materials industry - to the production of aerated concrete, in particular, foam concrete, used for the manufacture of any products from aerated concrete, more preferably for small wall blocks of industrial premises, multi-storey and individual residential buildings. More specifically, the invention relates to a method for preparing aerated concrete, to a raw material mixture for preparing aerated concrete and to aerated concrete prepared from such a raw material mixture by the aforementioned method.

State of the art

From the patent of the Russian Federation No. 2471753 C1, published on January 10, 2013, a method for producing foam concrete and a raw mixture for producing foam concrete are known, including, wt%: Portland cement 52.06-57.73, foaming agent PB-2000 0.24-0.25 , quartz sand 7.99-18.56, water 23.96-24.75. In addition to the above components, the raw mixture contains liquid soda glass and ground broken sheet glass. According to this method of producing foam concrete, quartz sand, broken glass and Portland cement are mixed in a separate container. In another container for 5 minutes a homogeneous foam is whipped from a 4% working solution of the PB-2000 foaming agent with the addition of liquid sodium glass. After preparing the foam, a mixture of dry components is gradually introduced into it, continuing to constantly stir the mass. After preparing the foam concrete mixture, it is poured into metal molds pre-oiled with oil and left until hardened. The disadvantage of this known from the prior art method is the low strength of foam concrete due to the absence of the effect of compression of pores in its porous structure, as well as due to the absence of resin in the raw mixture having the appropriate characteristics.

For the prototype of the invention, a method for producing foam concrete and a raw mixture is adopted according to the patent of the Russian Federation 2377225 C1, IPC С04В 38/10, published on December 27, 2009 The raw material mixture according to the prototype contains, wt%: Portland cement 30.0-32.0, foaming agent PB-2000 0.6-0.7, saponified wood resin (SDO) 0.7-1.0 and water 36.0- 37.0. In addition to the above components, the raw mix contains TPP ash and silica dust. According to the prototype in a foam generator, foam is whipped from a mixture of resin and a foaming agent (SDO and PB-2000) with water. All concrete components are mixed in a screw mixer, into which dry components are first fed: cement, TPP ash (fractions less than 0.14 mm), silica dust, and then prepared foam. From the mixer, the prepared mixture is evenly distributed in metal molds pre-oiled with oil and fed to the heat and moisture treatment, which is carried out according to the mode 3 + 9 + 3 hours at an isothermal holding temperature of 90 ° C. Then the finished products are removed from the molds and transported to the warehouse, where the material "ripens". The disadvantage of the method, the raw material mixture and the foam concrete according to the prototype is the low strength of the foam concrete due to the absence of the resin in the raw mixture, intended to create the effect of compression of the pore surface in it. Saponified wood resin used in the raw material mixture according to the prototype does not provide the desired effect in increasing the strength of foam concrete, since it does not have the necessary parameters for this, leading to the compression of the pore surface in the porous structure of foam concrete. In addition to increasing the strength of foam concrete, the use of resin in the foaming agent can lead to positive effects that are important for foam concrete - an increase in the softening coefficient of foam concrete and a decrease in its thermal conductivity coefficient.

Disclosure of invention

The technical objective of the invention is to obtain a new method for the preparation of foam concrete, to obtain a new raw mixture for the preparation of foam concrete (including for the manufacture of structural products) and to obtain a new foam concrete of increased strength, having improved performance indicators, estimated values of the softening coefficients and thermal conductivity.

The technical result consists in increasing the strength and softening coefficient while reducing the thermal conductivity coefficient of foam concrete (products) prepared by the claimed method, primarily due to the introduction into the claimed mixture of a resin together with a foaming agent having the appropriate indicators / characteristics to ensure the declared effect by compressing the pore surface porous structure of foam concrete during its curing. In this case, various types of cement can be used: Portland cement (including white and colored), Portland slag cement, alumina cement, pozzolanic cement or special cements, as well as fine aggregate and / or fillers (quartz sand, TPP ash, silica dust, etc.) ...

To achieve the above technical result, a method for the preparation of foam concrete is proposed, according to which the following steps are carried out:

- water is poured into the foam generator to prepare foam, to which a foaming agent is added (for example, PB-Lux brand according to TU 2481-004-59586231-2005 PB-Lux foam agent. Technical conditions) and a water-soluble resin (for example, urea-formaldehyde resin of the KF-Zh brand according to GOST 14231-88 Urea-formaldehyde resins. Specifications);

- mix the above components in a foam generator until foam is obtained;

- mix cement, fine aggregate and / or filler with water in a concrete mixer to prepare a homogeneous solution of the required consistency;

- the foam is fed into the concrete mixer with the solution from the foam generator and mixed until a homogeneous foam concrete mixture is obtained with the formation of a porous structure.

According to the present invention, PB Lux foaming agent can be used as a foaming agent.

According to the present invention, quartz sand can be used as fine aggregate.

According to the present invention, mixing until a homogeneous foam concrete mixture is obtained can be carried out for 2-5 minutes, the finished foam concrete mixture can be placed in pre-lubricated metal molds, and the obtained foam concrete samples can be subjected to heat and moisture treatment and / or kept under normal conditions, followed by testing them preferably at the age of 28 days.

According to the present invention, the components for the preparation of foam concrete can be used in the following ratio, wt%:

Portland cement 48.5-49.44 Fine aggregate 19.7-20.0 Foam concentrate (PB Lux) 0.16-0.18 Urea-formaldehyde resin (KF-Zh) 1.20-1.32 Foam water 9.8-10.0 Water for preparing cement mortar 19.7-20.0

According to the present invention, the pores of the porous structure of the foam concrete can have a diameter of no more than 2.0 mm, are uniformly distributed in its volume and are polyfractional.

Also, to achieve the above technical result, a raw material mixture for the preparation of foam concrete is proposed, containing Portland cement , a filler based on quartz sand, a PB Lux foaming agent according to TU 2481-004-59586231-2005, water for preparing a cement mortar and water for preparing foam, which is additionally contains urea-formaldehyde resin grade KF-Zh according to GOST 14231-88 with the following ratio of components, wt%:

Portland cement 48.5-49.44 Fine aggregate 19.7-20.0 Foaming agent 0.16-0.18 Urea-formaldehyde resin (KF-Zh) 1.20-1.32 Foam water 9.8-10.0 Water for preparing cement mortar 19.7-20.0

Also, to achieve the above technical result, the proposed foam concrete, prepared from the above raw mixture by the above method.

Implementation of the invention

The preparation of foam concrete is carried out in a concrete mixer, according to its characteristics close to the serially produced industrial installations. First, water is poured into the foam generator to prepare foam, a foaming agent, for example, PB Lux according to TU 2481-004-59586231-2005, and a water-soluble resin, for example, carbamide-formaldehyde resin of the KF-Zh grade according to GOST 14231-88. Then the above components are mixed until a foam with the required characteristics is obtained. Next, in a concrete mixer, Portland cement is mixed with a fine aggregate, for example, with quartz sand, and water to prepare a solution until a homogeneous mortar mixture is obtained. Foam from the foam generator is fed into the concrete mixer with the resulting mortar mixture. Then the solution and foam are mixed, preferably 2-5 minutes, until a homogeneous foam concrete mixture is obtained with the formation of a porous structure.

The finished foam concrete mixture is placed in pre-lubricated metal molds having, for example, dimensions of 100 × 100 × 100 mm ³ . The foam concrete samples molded in them are subjected to heat and moisture treatment and / or kept under normal conditions, followed by testing them, preferably at the age of 28 days. Tests of finished samples of foam concrete are carried out to determine the compressive strength in accordance with GOST 12852.1-77 “Cellular concrete. Method for determining compressive strength ", thermal conductivity coefficient - according to GOST 7076-87" Building materials and products "and water resistance - by the value of the softening coefficient, equal to the ratio of the compressive strength of water-saturated samples to the strength of samples in a dry state.

The compositions of the developed raw mixture for the preparation of foam concrete and the properties of foam concrete obtained on its basis by the above method are presented in Table 1.

Table 1

No.
p / p Compositions Consumption of materials, wt.% Compressive strength R _SJ, MPa Softening coefficient K _in , rel. units Thermal conductivity coefficient λ, W / (m ∙ K) one Cement (Portland cement)
Fine aggregate (quartz sand)
Foam concentrate PB Lux
Foam water
Water for preparing cement mortar 50.0
19.0
0.20
eleven
19.8 1.5-1.8 0.6-0.7 0.09-0.10 2 Cement (Portland cement)
Fine aggregate (quartz sand)
Foam concentrate (PB Lux)
Foam water
Water for solution preparation
Resin (carbamide-formaldehyde grade KF-Zh) 49.44
19.7
0.16
9.8
19.7
1.20 2.9 0.81 0.05 3 Cement (Portland cement)
Fine aggregate (quartz sand)
Foam concentrate (PB Lux)
Foam water
Water for solution preparation
Resin (carbamide-formaldehyde grade KF-Zh) 48.5
20.0
0.18
10.0
20.0
1.32 2.6 0.81 0.06 4 Cement (Portland cement)
Fine aggregate (quartz sand)
Foam concentrate (PB Lux)
Foam water
Water for solution preparation
Resin (carbamide-formaldehyde grade KF-Zh) 49.3
19.84
0.16
9.8
19.7
1.20 2.8 0.82 0.05

The average density of foam concrete in a dry state was 500-525 kg / m ³ .

In the claimed method for the preparation of foam concrete, the formation of a porous (cellular) structure occurs under conditions of low surface tension of solutions due to the presence of surfactant and urea-formaldehyde resin KF-Zh in the mixtures. Reduced surface tension, increased viscosity and mechanical strength of this layer, the absence of a noticeable pressure difference in the pores, dynamic effects in the process of mixture porization (mixing) ensure the fulfillment of one of the main principles of the thermodynamic stability of the system - the creation of the smallest surfaces at the gas - dispersion medium interface ... Therefore, in materials obtained by the claimed method (by the method of foaming), the porous structure is better than in materials obtained by gas swelling: the pores are smaller (not higher than 2.0 mm) and are uniformly distributed in the volume of the product, there are no through pores and cracks on interpore partitions, and the inner surface of the pores is smooth, dense, covered with a polymer film that squeezes it. The latter circumstance significantly reduces the level of tensile stresses on the pore contour during loading of foam concrete, which ensures the production of products with increased strength. Foam porosity method has the ability to control the volume of porosity and characteristics of the porous structure of the material, in particular, the creation of polyfractional pores. This is achieved by regulating the content of surfactants and urea-formaldehyde resin KF-Zh in the mixture (solution) and the hydrodynamic mixing conditions (for example, by changing the rotation speed of the mixing shaft, the surface area of the mixer blades and its shape, using mixers with several mixing shafts rotating at different speeds).

As can be seen from Table 1, the optimal compositions are compositions No. 2 - 4. From Table 1 it follows that the strength and water resistance, characterized by the softening coefficient obtained from the raw foam concrete mixture prepared according to the claimed invention, is significantly higher than that of the prototype, transferring the foam concrete from non-water resistant (composition 1) into a water resistant material (compositions 2 - 4) with a softening coefficient above 0.8. At the same time, a low value of the thermal conductivity coefficient was obtained, and the foam concrete in terms of physical and technical indicators meets the requirements of GOST 25485-89 “Cellular concretes. Technical conditions ", transferring D500 foam concrete from heat-insulating (composition 1) to structural and heat-insulating (compositions 2 - 4) with higher operational properties.

Claims (13)

1. A method of preparing foam concrete, according to which the following steps are carried out: - water is poured into the foam generator for the preparation of foam, the PB-Lux foaming agent and urea-formaldehyde resin KF-Zh; - mix the above components in a foam generator until foam is obtained; - Mix Portland cement in a concrete mixer, fine aggregate - quartz sand and water to prepare a homogeneous solution of the required consistency; - foam is fed into the concrete mixer with cement mortar from the foam generator and mixing is carried out for 2-5 minutes until a homogeneous foam concrete mixture is obtained with the formation of a porous structure; - the finished foam concrete mixture is placed in pre-lubricated metal molds; - the obtained foam concrete samples are subjected to heat and moisture treatment and / or kept under normal conditions, while the components for preparing the foam concrete mixture are used in the following ratio, wt%: Portland cement 48.5-49.44 Fine aggregate - quartz sand 19.7-20.0 Foam concentrate PB-Lux 0.16-0.18 Urea-formaldehyde resin KF-Zh 1.20-1.32 Foam water 9.8-10.0 Water for preparing cement mortar 19.7-20.0 2. The method according to claim 1, in which the pores of the porous structure have a diameter of not more than 2.0 mm, are uniformly distributed in the volume of foam concrete and are polyfractional. 3. Raw mix for the preparation of foam concrete, containing Portland cement, fine aggregate, foaming agent, water for making foam and water for preparing cement mortar, characterized in that it contains quartz sand as a fine aggregate, PB-Lux foaming agent as a foaming agent and additionally urea-formaldehyde resin KF-Zh with the following ratio of components, wt%: Portland cement 48.5-49.44 Fine aggregate - quartz sand 19.7-20.0 Foam concentrate PB-Lux 0.16-0.18 Urea-formaldehyde resin KF-Zh 1.20-1.32 Foam water 9.8-10.0 Water for preparing cement mortar 19.7-20.0 4. Foam concrete prepared from the raw mixture according to claim 3 by the method according to any one of claims. 12. 5. Foam concrete according to claim 4, in which the pores of the porous structure have a diameter not exceeding 2.0 mm, are uniformly distributed in the volume of foam concrete and are polyfractional.