RU2626092C1 - Method for manufacturing variatropic cellular concrete - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method for manufacturing variational cellular concrete includes pre-treatment of a binder, a fine aggregate, and mixing water separately with low-temperature nonequilibrium plasma for 1⋅10^-2 up to 5⋅10^-2 s, mixing the components to obtain a homogeneous aerated concrete mixture, pouring it into a perforated mould, the inner surface of which is preliminarily covered with glass, carbon or basalt fiber, closing the mould with a cover and fixing it, hardening and stripping.

EFFECT: increasing the coefficient of structural quality of products based on variatoric cellular concrete with the reinforced surface, simplifying the technology of its production.

3 ex, 1 tbl

Description

The invention relates to the building materials industry and can be used for the production of structural heat-insulating products and cellular concrete structures.

A known method for producing variastropic cellular products, including filling a foam concrete mixture with a mold at 55% of its depth, feeding the foam into the mold and mixing it with a foam concrete mixture in a layer 40-50% thick of the mold depth. Mixing is carried out using a device consisting of a drill with different working bodies, the intensity of mixing varies with the depth of the processed layer. The properties of the obtained variastropic foam concrete: average density 500-600 kg / m ³ , maximum density in the bottom layer 800-820 kg / m ³ , minimum density 390-430 kg / m ³ , compressive strength 1.5-5 MPa, thermal conductivity 0.2-0.35 W / (m⋅K) [1].

The disadvantage of this method is the complexity of the technology for the formation of variastropic products, which consists in the need for a two-stage filling of the mold and mechanical mixing of the foam with the foam concrete mixture, which leads to foam syneresis, an increase in V / C and, consequently, a decrease in strength indicators. This method allows to obtain variastropic cellular concrete with unidirectional (one-vector) change in properties. Moreover, the coefficient of structural quality (K.K.K.) (the ratio of strength to the average density of products) does not exceed 0.008.

The closest analogue is a method for producing variatropic cellular concrete, including the formation of the variatropic structure of the product in a closed form with perforated surfaces. Before pouring the moldable mixture obtained on the basis of non-activated raw materials, the pan, sides and lid of the mold are lined with plastic wrap, with a perforation coefficient greater than in the mold. If necessary, the completed form is subjected to vibration [2].

The disadvantages of this method include the following: one-time use of the covering material, which is subsequently removed from the surface of the product and needs to be disposed of. When using the blocks obtained by this method in construction, an additional device is required on their surface of a reinforcing material (reinforcing mesh) to ensure reliable adhesion to protective, protective and decorative coatings, which leads to an increase in the complexity and cost of construction work. Also, when using perforated plastic film as a covering material, unequal conditions for hardening Portland cement are created (changes in moisture content in the areas adjacent to the perforation holes in relation to the zones between the perforation holes), as a result of which during operation, in particular when changing the humidity conditions, on the surface of the products defective places occur.

The technical result of this invention is to increase the coefficient of structural quality of products based on variatropic cellular concrete with a reinforced surface, simplifying the technology of its manufacture.

This goal is achieved by the fact that in the method of manufacturing variastropic cellular concrete, comprising mixing the components to obtain a homogeneous aerated concrete mixture, pouring the mixture into a perforated form, the inner surface of which is pre-covered with non-woven material, closing the form with a lid and fixing it, hardening and stripping, before mixing the components the binder, fine aggregate and mixing water are separately pretreated with low-temperature nonequilibrium plasma for f 1⋅10 ^-2 -5⋅10 ^-2 s. The inner surface of the perforated shape is covered with glass, carbon or basalt fiber.

The goal is achieved by:

- pretreatment of astringent, fine aggregate and water in the installation of low-temperature nonequilibrium plasma NTNP;

- the formation of variatropic cellular structure in closed perforated forms;

- lining the inner surface of the mold with a non-woven fibrous material — glass, carbon, or basalt fiber.

Portland cement CEM I 42.5 N GOST 31108-2003 or slag Portland cement CEM III / A 32.5 N GOST 31108-2003 is used as a binder.

As fine aggregate, quartz or diatomaceous sand with a fineness modulus M _k = 1.9, or marble chips (GOST 8736-2014) is used.

As an additive, air quicklime calcium lime without additives of the 1st grade is used (GOST 9179-77).

As a blowing agent, aluminum powder PAK-1 or PAK-2 (GOST 5494-95) is used.

Example 1

The inner surface of the perforated shape measuring 300 × 300 × 600 is covered around the perimeter with a non-woven fibrous material, for example glass fiber. The raw materials of the aerated concrete mixture, namely the binder, fine aggregate and mixing water, are separately treated in a low-temperature nonequilibrium plasma (NTNP) installation.

The NTNP installation of a continuous type consists of a funnel for feeding material, a plasma generator, a power source, a container for the processed material and a dust collector, NTNP in laboratory installations is generated by an AC source with voltage up to 8000 V and frequency up to 40 kHz. An NTNP region is created between the plasmatron electrodes with the parameter value E / N = 15 × 10 ^-16 V16cm ² , the degree of ionization (α) is 1%, and the plasma temperature is 6⋅10 ⁴ K. The processing time of the raw components varied from 1⋅10 ^-2 to 5⋅10 ^-2 s.

The binder treated in NTNP is Portland cement CEM I 42.5N 31 parts by weight, fine aggregate processed in NTNP is quartz sand with M _k = 1.9 41 parts by weight, the blowing agent is PAP-2 aluminum powder 0.07 wt. hours, quicklime calcium with a content of CaO + MgO of at least 70% 1.7 wt.h. and processed in NTNP mixing water 26.23 wt.h. mix to obtain a homogeneous mixture, which is poured into a pre-prepared form. After filling the mold with aerated concrete mixture, the mold cover is closed and fixed. After the process of gas formation, the formation of the variatropic cellular structure and the achievement of the formwork massif, the product is removed from the mold. The tests were carried out after 28 days of hardening under normal conditions (at a temperature of 20 ° C and humidity of 90-100%).

As a result of the process of gas formation in a closed perforated form, an excess pressure is created at which the fiber coating material is saturated and impregnated with a cement paste, which after curing forms a reinforced surface layer. Due to the device on the inner surface of the perforated shape of the lining of non-woven fibrous material, the molding mixture, consisting of a binder, fine aggregate, blowing agent, lime and water, does not reach the perforation holes of the form, through which only the gas component is removed, which eliminates the need for cleaning.

Example 2

The same as example 1, but without prior activation of the binder, fine aggregate and mixing water in the NTNP installation.

Example 3

The manufacture of products according to the prototype. Prepare a mixture to obtain aerated concrete. The non-activated raw components of the mixture (binder, fine aggregate, water and a blowing agent) are mixed in a single step to obtain a homogeneous mass and poured into a pre-prepared perforated mold (300 × 300 × 600), where the sides and lid are lined with plastic film, with a perforation coefficient greater than in form. The mold cover is closed and fixed. After the process of formation of the variastropic cellular structure is completed and the array reaches the formwork strength, the product is removed from the mold.

Tests of the samples obtained in examples 1-3 were carried out after 28 days of normal hardening. To compare the properties of the obtained samples, the coefficients of variability and structural quality were determined, the results are presented in the table.

The proposed method allows to obtain variastropic products based on cellular concrete, which are gradient systems with high strength of the peripheral (external) layers and low thermal conductivity of the central layers of the product. The high density of the outer layers leads to an increase in the structural properties of the products, and the low density of the central part determines the preservation of the heat-insulating properties of the products. The reinforced external surface of the products allows their use for the application of protective-decorative and decorative coatings without additional external reinforcement.

Information sources

1. Patent RU No. 2243190, 12/27/2004.

2. UA patent No. 49265, September 16, 2002.

Claims (1)

A method of manufacturing variastropic aerated concrete, including mixing the components to obtain a homogeneous aerated concrete mixture, pouring it into a perforated form, the inner surface of which is pre-covered with non-woven material, closing the form with a lid and fixing it, hardening and formwork, characterized in that it is binder, fine before mixing the components filler and mixing water, separately pretreated nonequilibrium low-temperature plasma for 1⋅10 ^{-2 -2} -5⋅10 with, and inside the perforated surface is covered with glass, carbon or basalt fiber.