RU2778225C1 - Method for obtaining a foam concrete mixture - Google Patents

Abstract

FIELD: construction materials.

SUBSTANCE: invention relates to the production of foam concrete used in the construction and repair of residential, industrial buildings and structures where continuous supply of foam concrete mixture is required. The method for obtaining a foam concrete mixture includes mixing in a given ratio of cement with water, filler: sand fractions less than or equal to 0.315 mm and/or a reinforcing additive: microfiber in a mixer-activator with a rotation speed of 200-500 rpm with heating of the mixture to 30 - 45 degrees Celsius and hydro-activation of cement at a water-cement ratio from 0.28 to 034, preparation of the foaming agent by stirring for one minute in a container of protein foaming agent concentrate with water in a ratio from 1:50 to 1:25, followed by aeration of the resulting foaming agent solution with compressed air at a pressure of 0.5 - 0.6 MPa in a foam generator until foam is formed with a multiplicity of 20 - 40, obtaining a foam concrete mixture at the place of application of foam concrete by mixing in a mixer-porizer with a rotation speed of working bodies 100 - 500 rpm in a given ratio of the specified activated cement mixture and the resulting foaming agent solution.

EFFECT: development of a method that provides continuous production of foam concrete mixture directly at the construction site without loss of quality of the foam concrete mixture.

1 cl, 1 dwg, 3 ex

Description

The present invention relates to the field of producing foam concrete in various sectors of construction, in particular in the construction and repair of residential and industrial buildings and structures, where a continuous supply of foam concrete is required.

The main disadvantages of the production of foam concrete mix by known methods include the cyclical production, which entails a large heterogeneity of the mixture not only from batch to batch, but also in the same batch in the upper and lower parts of the mixer, high water-cement ratio, relatively low initial and final strength , large shrinkage, the formation of shrinkage cracks, and in monolithic foam concrete it is also impossible to pour light foam concrete with a layer more than 50 cm high at a time. In addition, according to the known technology, it is difficult to obtain high-quality heat-insulating foam concrete of low density (200 kg/m ³ and below). These shortcomings hinder the widespread use of foam concrete in construction.

Known methods for producing foam concrete close to the claimed technical essence and the achieved result: SU 461916, published 02/28/1975; RU 2099313, published 12/20/1997; RU 2197380 published. 09/10/1999.

The disadvantages of the known methods are the cyclic (periodic) mode of operation, the relatively low productivity of the equipment, the high heterogeneity of the foam concrete and the imperfection of the pore structure, and, as a result, the high shrinkage and low mechanical strength of the foam concrete.

A known method for producing foam concrete, which is the closest analogue to the claimed technical solution [RU 2581068, published: 10.04.2016]. A known method for producing foam concrete includes mixing in a given ratio of cement with water, while mixing cement with water is carried out in mixers with the possibility of activating the cement mixture, obtaining foaming agent and obtaining foam concrete.

The disadvantages of the known method are the complexity and multi-stage technology for producing foam concrete, in which the manufacturing process of foam concrete is extended into 3 stages. The known method requires rather complex equipment, especially at the last, third stage, at which, in fact, the final process of manufacturing foam concrete takes place, while at this stage it is very difficult to control the quality of the resulting foam concrete mixture, tk. this process occurs during the transportation of the foam mass from the mixer-aerator through a special foam-mass pipeline-structure former in the form of a diffuser to the place where the foam concrete is placed in the formwork. The diffuser is a pipeline with a variable section, in which, due to the pressure drop at the beginning and end of the pipeline, the foam ratio changes from 2-5 to 8-15. The manufacture of a diffuser with a variable cross-section along the length is a complex technical and technological task, since when changing the length of the pipeline-diffuser or the height of the foam concrete mixture, it is necessary to recalculate each time, and then redo the variable cross-sectional areas of the pipeline-diffuser along the length. The authors of the well-known method mistakenly consider foam with a multiplicity of 8-15 to be high-expansion, and contributing to the production of high-quality foam concrete in low and ultra-low densities, while, according to GOST R 50588-93 "Foam concentrates for extinguishing fires", foam with a multiplicity of up to 20 is considered low-expansion, and the quality of foam concrete, especially in light and ultra-light densities, largely depends on the quality of the foam. From open sources it is known (the article "Basic parameters and characteristics of foam for foam concrete" on the website LIGHTBETON (Lightweight Concrete) www.Litebeton.ru) that it is recommended to use foam with a multiplicity of 15-35 for the production of high-quality foam concrete. Thus, the known technology allows, in the best, ideal case, to obtain foam with an expansion of 15, which is the minimum allowable for the production of foam concrete, while for the production of foam concrete of light and ultralight densities, the expansion of foam should be in the range from 25 to 40. Therefore, the use of foam with a multiplicity of 8-15 in the known method will not be able to provide high-quality stable foam concrete of light and ultra-light densities (from 300 kg/m ³ to 70 kg/m ³ ) as stated in the known method. The main disadvantage of the known technology is that the actual maximum range of movement of the foam concrete mixture from the mixer-aerator to the place of laying in the formwork is 25 meters horizontally, because in such a case, the diameter of the foam structurant at the outlet will be 20 cm (with 5 cm at the inlet), as indicated in FIG. 7 known analogue, and even in this case, the use of such a foam pipeline is problematic, because it will be impossible to pour foam concrete into formwork with a wall thickness of less than 20 cm. Moreover, at a construction site, the pouring site is very often located at a distance of 30-40 meters or more, and at a height of over 30 meters.

The complexity of the known technology and the constant need for calculations does not contribute to its widespread use in practice and is inaccessible to small businesses. The Applicant has not found any operating industrial installations using known technology.

The technical task to which the claimed invention is directed is to eliminate the disadvantages of analogues, to develop an improved method that allows continuous production of a foam concrete mixture directly at the construction site using compact and high-performance equipment, while the manufacturing process is divided into two stages: the production of an activated cement slurry (or activated cement-sand mortar) in the mixer-activator at 400 rpm with the supply of the solution (or suspension) through the hose directly to the place of laying the foam concrete mixture, even if this place is located on the 10th floor and above, where the production of foam concrete takes place in a compact and high-performance mixer-porizer, in close proximity to the place of laying.

The technical result, which the claimed method of obtaining a foam concrete mixture is aimed at, is a high-performance continuous mode for preparing a foam concrete mixture, the possibility of producing a foam concrete mixture directly at the place of its laying, which can be located at a great distance and at a considerable height from the installation site of the main equipment, which makes it possible to exclude loss of quality of the foam concrete mixture at the stage of its transportation from the place of manufacture to the place of laying in the formwork.

To achieve the specified technical result, the method for producing a foam concrete mixture includes mixing in a given ratio of cement with water, aggregate and additives, while mixing cement with water and additives, aggregate is carried out in mixers with the possibility of activating the cement mixture, obtaining foaming agent, obtaining foam concrete, mixing in the mixer of the activated cement mixture is carried out at a water-cement ratio from 0.28 to 0.34, obtaining the foaming agent is carried out by mixing the protein foaming agent concentrate with water in a ratio of 1:50 to 1:25 in a container, followed by aeration with compressed air,production of foam concrete is carried out by mixing in a mixer-porizer in a given ratio of activated cement mixture and foaming agent until foam concrete is formed with a foam ratio of 20-40, while mixing the activated cement mixture and foaming agent is carried out for a given amount of time at the place of application of foam concrete.

Significant differences between the proposed method and the known ones are:

1. The production technology of the foam concrete mixture according to the proposed method takes place in 2 stages, instead of 3 stages, as in the known technology [the closest analogue of RU 2581068, published: 04/10/2016], and can be described in two words "hydroactivation-porization", instead of " activation-aeration-structuring".

2. According to the proposed technology, at the first stage, to mix the binder, aggregates, additives and water, an activator mixer is used without cavitation effect and with a rotation speed of the working bodies of 200-500 rpm, instead of 1000-1500 rpm in an activator mixer with cavitation effect in a known technology and a known installation, while the working bodies of the proposed mixer-activator are fundamentally different from the working bodies of high-speed cavitation mixers in a known technology and a known installation.

3. In the proposed technology, the pump for pumping a cement-sand mixture or cement slurry is equipped with a capacious receiving hopper, therefore, the proposed technology does not require an intermediate storage tank for the activated mixture (suspension), as is the case in the known technology and in the known installation.

4. The proposed technology assumes the use of modern environmentally friendly protein foaming agents, which are very easily mixed with water by manually mixing with any paddle-shaped object for one minute and do not require the use of a mixer-activator with a cavitation effect and with a rotation speed of the working bodies of 1000-1500 revolutions per minute. minute, as is the case in known technology in a known installation.

5. In the well-known technology, all equipment is located together, on the same platform and at the same level, and the distance between the pump for pumping the activated mixture (suspension), the pump for pumping the foam concentrate solution to the mixer-aerator, in which all components are mixed and the initial stage of production of foam concrete mixture is taken as the minimum possible and is several meters, and the actual distance of the foam concrete mixture supply is no more than 25 meters, and the proposed technology provides that all the main equipment, including pumps for pumping the activated mixture (suspension) and the foam concentrate solution, are located in one place, and a compact mixer-porizer, in which all components are mixed and the finished foam concrete mixture is produced, is located directly at the place of laying the foam concrete mixture, while the distance from the pumps to the mixer-porizer in the proposed installation can be up to 100 meters or more both horizontally and vertically.

6. In the known technology, the mixing of all components and the initial stage of manufacturing the foam concrete mixture takes place in a mixer-aerator with a rotation speed of the working bodies of 1000-1500 rpm and at an excess air pressure of up to 2.5 MPa, and in the proposed technology, mixing of all initial components, including reinforcing (microfiber of different types), takes place in a mixer-porizer with a speed of rotation of the working bodies of 100-500 rpm and at normal atmospheric pressure.

7. In the known technology, in the process of manufacturing the foam concrete mixture, a foam expansion rate of 8-15 is achieved, and in the proposed technology and on the proposed installation, the foam expansion rate reaches 20-40, which is a significant difference.

8. In a well-known technology, the process of manufacturing a foam concrete mixture occurs in several stages and is stretched both in time and space: first, all components are mixed at high air pressure up to 2.5 MPa and the process of porousization of the activated mixture begins, after which the prepared foam mass enters into the channel of the foam mass pipeline-structurant in the form of a diffuser that combines the continuous transportation of the foam mass and its defect-free structuring in the free movement mode under the influence of the pressure difference at the inlet and outlet of the channel while limiting the maximum linear flow rate and the minimum residence time of the foam mass in the channel, and in the proposed technology, the manufacturing process foam concrete mixture occurs continuously, in one stage and for several seconds at atmospheric pressure in a high-performance mixer-porizer, with a volume of 10 to 20 liters, and the finished foam concrete mixture is fed through a conventional pipeline (hose) with a diameter of 50-60 mm. tsya without loss of quality in the formwork.

The inventive method is illustrated by a diagram, where figure 1 shows the following symbols:

1 - Mixer-activator of binders;

2 - Water dosing pump;

3 - Bulk material dispenser;

4 - Gerotor pump with a receiving hopper;

5 - Control panel for dosing components;

6 - Hose for supplying activated cement slurry;

7 - Container with a foaming agent solution;

8 - Foaming agent supply pump;

9 - Hose for supplying a foaming agent solution;

10 - Compressor;

11 – Compressed air supply hose;

12 - Foam generator;

13 - Mixer-porizer;

14 - Control panel for the production of foam concrete;

15 - Hose for supplying the finished foam concrete mixture;

16 - Formwork for pouring foam concrete mixture;

17 - Water tank.

The method is carried out as follows. Before starting the process of manufacturing a foam concrete mixture according to the proposed technology, in a plastic container 7 with a volume of at least 1 m ³ , a working solution of a foaming agent is made by diluting the concentrate of a protein foaming agent with cold water in a ratio of 1:50 to 1:25, depending on the hardness of the water and the quality of the foaming agent. Next, the pump for supplying the foam concentrate solution 8 is turned on, the resulting foam concentrate solution is fed through the hose 9 to the foam generator 12. The compressor 10 is turned on and compressed air is supplied through the hose 11 at a pressure of 0.5-0.6 MPa to the foam generator 12, while the foam generator is adjusted to the required density and foam performance for each specific foam concrete density. After the foam generator is set up and the foam of the desired density is obtained, they begin to manufacture and activate the cement slurry or cement-sand mortar in binder activator mixers 1 (cement-sand mortar or cement slurry), each of which is equipped with a frequency converter with the ability to change mixer speed from 0 to 500 rpm. The control is carried out from the control panel 5. Water is poured into the mixer-activator 1 from the tank 17 using a water metering pump 2 in an amount corresponding to the required value of the water-cement ratio (from 0.28 for ultra-light heat-insulating foam concrete to 0.4 for structural) . Then one of the mixer-activators of binders 1 is turned on at medium speed and smoothly increased to maximum, dry additives and cement are poured from the dispenser 3. If it is planned to obtain foam concrete with a density above 350 kg / m ³ , then a certain amount of sand is added to the mixer-activator 1 , which is calculated depending on the quality of sand and the required density of foam concrete. Sand is preferably used in fine fractions (less than or equal to 0.315 mm). At the same time, the higher the density of foam concrete is planned, the more sand is added to the mixture. After adding all the components, the mixer-activator 1 continues to operate at maximum speed for another 2 minutes. At this time, the production and activation of binders (cement slurry or cement-sand mortar) is started in the second mixer-activator of binders 1, which is located on the other side of the pump 4. After two minutes of operation of the first mixer-activator of binders with all components of the mixture, the turns this mixer-activator is reduced to low speed, the shutter is opened at the bottom of the mixer and the resulting activated binder mixture is discharged into the pump hopper 4, while the specified binder pump is equipped with a frequency converter. After the mixture from the first mixer-activator was drained into the receiving hopper of the pump 4, the valve of the unloaded mixer-activator is closed, then the next batch of the binder mixture is started in this mixer-activator. To implement the continuous mode of preparation of the foam concrete mixture, the activated cement slurry or the cement-sand mixture is alternately fed into the receiving hopper of the pump 4 from both mixer-activators 1. The prepared binder mixture is continuously fed at a certain speed into the mixer-porator 13, where the binder mixture is mixed in a certain proportion with foam, which is continuously produced in the foam generator 12 and at a certain speed is continuously fed into the mixer-porator 13. In the mixer-porizer 13, the binder mixture is thoroughly turbulently mixed with foam to obtain foam concrete of the required density. All parameters of the foam and foam concrete are adjusted using the control panel 14, which controls the performance of the pump 4, the performance of the foam concentrate solution pump 8, and the performance of the compressor 10. formwork 16 or on the horizontal surface of the slab for pouring.

In the claimed method, the equipment for producing a binder mixture consists of two mixer-activators of a cement-sand mortar or cement slurry, two dosing pumps for water, dispensers of bulk materials, a gerotor pump with a receiving hopper, a control panel for dosing all components, a container with a foam concentrate solution , the pump for supplying the foaming agent solution and the compressor are placed on the construction site at zero height. The foam generator, the mixer-porator 13 and the control panel 14 are placed at the required height and distance from the main equipment, next to the formwork into which the foam concrete mixture is poured.

The claimed method for the production of foam concrete was repeatedly tested by the applicant on a working prototype of an experimental plant in 2021. Below are examples of the implementation of the proposed method.

Example 1. In one of the mixer-activators of the installation, cement was mixed with water, sand and additives. The mixer-activator was a vertical mixer with a volume of 150 liters. with a rotation frequency of the working body of 200-500 rpm. In the process of mixing the cement slurry, accelerated and deep hydroactivation of cement in an aqueous medium was ensured with heating of the mixture to 30-45 degrees Celsius. Using a gerotor pump, the resulting mixture was fed through a hose with a diameter of 60 mm to a height of 10 m to the place where the foam concrete mixture was poured under an overpressure of 1.2 pgH, into a high-speed mixer-porizer with a volume of 10 liters. The foaming agent solution was prepared separately in a plastic container at the ratio: 4 kg of protein foam concentrate per 100 kg of water. In this case, the entire installation, including the compressor, containers with a foaming agent solution were placed at zero, and the high-speed mixer-porizer was located at a height of 10 meters in relation to the installation. Within 3 minutes, the required density was set by the adjusting control devices, and the foam concrete mixture of the required density was continuously produced. The inventive method made it possible to obtain a foam concrete mixture using a continuous technology with a low water-cement ratio (0.28), a density of 100 kg/m ³ , with increased initial and final strength (not less than 30%).

Example 2. In the same mixer-activators of the installation, cement was mixed with water and additives. In the process of mixing the cement slurry, accelerated and deep hydroactivation of cement in an aqueous medium was ensured with heating of the mixture to 45 degrees Celsius. Using a gerotor pump, the resulting mixture was fed through a hose with a diameter of 60 mm to a height of 6 m to the place where the foam concrete mixture was poured under an overpressure of 1.15 pgH, into a high-speed mixer-porizer with a volume of 10 liters. The foaming agent solution was prepared separately in a plastic container at the ratio: 4 kg of protein foam concentrate per 100 kg of water. In this case, the entire installation, including the compressor, containers with a foaming agent solution were placed at zero, and the high-speed mixer-porizer was located at a height of 6 meters in relation to the installation. Within 2 minutes, the required density was set by the adjusting control devices, and the foam concrete mixture of the required density was continuously produced.

The inventive method made it possible to obtain a foam concrete mixture using a continuous technology with a low water-cement content (0.3), a density of 200 kg/m ³ , with increased initial and final strength (not less than 30%).

Example 3 In the plant mixer-activators mentioned above, cement was mixed with water, sand and additives. In the process of mixing the cement slurry, accelerated and deep hydroactivation of cement in an aqueous medium was ensured with heating of the mixture to 45 degrees Celsius. Using a gerotor pump, the resulting mixture was fed through a hose with a diameter of 60 mm to a height of 12 m to the place where the foam concrete mixture was poured under an overpressure of 1.3 рgH, into a high-speed mixer-porizer with a volume of 10 l. The foaming agent solution was prepared separately in a plastic container at a ratio of 3 kg of protein foam concentrate per 100 kg of water. In this case, the entire installation, including the compressor, the tanks with the foaming agent solution were placed at zero, and the high-speed mixer-porizer was located at a height of 12 meters in relation to the installation. Within 2 minutes, the required density was set by the adjusting control devices, and the foam concrete mixture of the required density was continuously produced.

The inventive method made it possible to obtain a foam concrete mixture using a continuous technology with a low water-cement content (0.31), a density of 400 kg/m ³ , with increased initial and final strength (by 30%).

The most effective field of application of foam concrete, obtained from the foam concrete mixture by the claimed method, is the insulation of roofs, external walls of buildings and various communications. A promising direction of application of the method is the construction of energy-efficient low-rise buildings, all structures of which are made of foam concrete reinforced with a frame. Using this technology, it is also possible to build cheap and comfortable attic floors above 5- and 9-storey buildings with apartments for young people.

Claims (1)

A method for producing a foam concrete mixture, characterized by mixing in a given ratio of cement with water, aggregate - sand fractions less than or equal to 0.315 mm and / or reinforcing additive - microfiber in an activator mixer with a rotation speed of the working bodies of 200 - 500 rpm with heating the mixture up to 30 - 45 degrees Celsius and hydroactivation of cement, mixing in the mixer-activator of the specified cement mixture is carried out at a water-cement ratio of 0.28 to 034, the preparation of the foaming agent is carried out by mixing for one minute in a container of a concentrate of a protein foaming agent with water in a ratio of 1:50 to 1 :25 followed by aeration of the resulting foam concentrate solution with compressed air at a pressure of 0.5 - 0.6 MPa in the foam generator until foam is formed with a ratio of 20 - 40; - 500 turnover ov per minute in a given ratio of the specified activated cement mixture and the resulting foam solution.

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