RU2245246C1 - Installation for production of foamed concrete by aeration - Google Patents

Abstract

FIELD: production of foam concrete.

SUBSTANCE: the invention is dealt with devices for preparation of foam concrete. The invention allows to distribute the dosed amount of compressed air uniformly. The installation for preparation of foam concrete by aeration includes a baromixer supplied with a rotor planted on a shaft, a bogie, a drive, a control panel, a control instrumentation, an air outlet for compressed air feeding in the body the baromixer. The rotor of baromixer is made in the form of a hollow cone with a corrugated surface, the base of which rests on an elastic element with a reversible deformation. On perimeter of the cone there are slots. The shaft of the rotor is supplied with a channel connected with a cavity of a channeled taper through open slots.

EFFECT: the invention ensures a uniform distribution of the dosed amount of compressed air.

2 dwg

Description

Installation for the preparation of foam concrete by aeration is designed to obtain a foam concrete mixture used in the construction industry.

Currently, the following methods are used in foam concrete technology for the preparation of foam concrete mix (Gridchin AM “Bulletin of the Belgorod State Technological University named after V.G. Shukhov”, Scientific and Theoretical Journal, Belgorod, issue. No. 4, p. 120 2003 g):

1. Porization of concrete mix with pre-prepared foam:

- the traditional foam method, which consists in separately preparing high-level foam and porous solution, in their subsequent mixing in a separate mixer or mixer for preparing a solution;

- a method of dry mineralization of the foam, which consists in the preliminary preparation of low-level foam and its mineralization with the dry components of the mixture by gradually and uniformly introducing them into the prepared foam mass while stirring in a mixer.

2. Preparation of foam concrete without foam:

- a method of preparing foam mass by aeration based on air entrainment with a solution of a binder and siliceous component with a foaming agent during their high-speed mixing.

In the first two methods of preparing a foam concrete mix, foam generators are used in the technological kit of the equipment set to prepare foam. So, the technological kit of the Italian company “LASTON” model 5 / 8M includes a mixer, aerator (foam generator), pump (“Materials of the international scientific-practical conference“ Foam-concrete-2003 ”April 9-11, 2003 Belgorod). This is their main disadvantage, since the need for the use of foam generators complicates the equipment for the preparation of foam concrete and increases the cost of the resulting porous material.

A method of preparing foam mass by aeration is based on air entrainment with a solution of a binder and silica component with a foaming agent during their high-speed mixing.

When preparing a foam concrete mixture by aeration, there is no need to use a foam generator. A positive feature of the aeration method is that partial activation of the mixture is observed, obtaining a finely porous cellular structure of foam concrete, which is interconnected with the strength of foam concrete and the coefficient of porosity (V. A. Martynenko, “Cellular and porous lightweight concrete”, Dnepropetrovsk, “Porogi”, 2002) .

However, due to the fact that all porosity processes are combined in one unit (in a high-speed mixer), a number of special technical and technological requirements are presented to it. Technical requirements include: the volume of the mixer and the ratio of its main dimensions, the speed of rotation of the shaft, the dynamics of the flow of the mixture with stirring. Technological factors include load factor by volume, aeration time, quantity and type of blowing agents, initial and final mobility of the concrete mix. The multifactorial interconnection of the mixture preparation process significantly affects both its preparation time and the properties of foam concrete products.

One of the disadvantages of producing aerated concrete by aeration is that when using aeration, fluctuations in the density of the concrete mixture are observed due to the lack of an accurate dosage of the components of the mixture and control of its density. Including non-dosed supply of compressed air into the cavity of the mixer. In this case, air cavities in the volume of the mixture are distributed unevenly. The diameters of the air cells are scattered over a wide range, macropores are formed. With a large number of macropores, the air emulsion passes into the cellular structure of foam concrete (L.D. Shakhova, V.V. Balyasnikov “Frothers for aerated concrete”, p. 98, Belgorod, 2002), which negatively affects the thermal insulation and strength characteristics of the material.

These drawbacks are dry, for example, to a small-sized mobile concrete mixer type “SIC” (V. A. Martynenko, “Cellular and porous lightweight concrete”, p. 142, Dnepropetrovsk, “Porogi”, 2002). A concrete mixer of this brand includes a trolley, a vertically located bar mixer mounted on it with a hermetically sealed lid. Inside the housing of the mixer is a rotor. A drive for rotating the rotor shaft, an installation control panel is installed on the trolley. The foam concrete mixer is equipped with instrumentation. A fitting is integrated in the lower part of the mixer housing, through which compressed air is supplied to the mixer cavity to aerate the concrete mixture. The main disadvantage of this design is that compressed air is supplied to the mixer cavity only in the area adjacent to the mixer body on one side. Such an eccentric arrangement of the nozzle does not contribute to a uniform distribution of air bubbles in the entire volume of the mixture, and undosed air supply leads to air pores of various diameters. This negatively affects the strength and thermal insulation properties of the resulting material.

The aim of this invention is to meter the volume of compressed air supplied to the internal cavity of the aeration mixer; its uniform distribution in the entire volume of the mixture; the production of air pores in a mixture with the same, predetermined diameters.

The task is achieved by supplying compressed air directly to the mixing zone of the solution, i.e. into the zone located around the rotor of the mixer bar. For this, the rotor is made in the form of a hollow cone with a corrugated surface. The base of the cone rests on an elastic element with reversible deformation (for example, of rubber), and slots are made along the perimeter of the base of the cone. The rotor shaft is provided with a channel that communicates with the cavity of the corrugated cone of the rotor through the through slots.

In the initial state, the slots are closed by an elastic element, since the base of the rotor cone is pressed against it and the elastic element, being deformed, is pressed into the slots and overlaps them. When compressed air is supplied to the inner cavity of the rotor cone, through the rotor shaft channel and through slots, the elastic element is forced through by air and leaves the slots. Bubbles of air from the cavity of the conical rotor penetrate into the mixer body and, not having time to increase to macro sizes, are disrupted by a turbulent flow of cement mortar, which is mixed in the mixer body by a rotating rotor, and aerate the solution, evenly distributed in its mass. Thus, by changing the pressure of the air supplied to the inner cavity of the rotor, while maintaining a constant number of revolutions of the rotor shaft, it is possible to produce air bubbles of any given size. As you know, the smaller the size of micropores in foam concrete and the larger their number per unit volume of foam concrete, the better the mechanical and heat-conducting properties of the material.

Figure 1 shows the communities view of the installation for preparing aerated concrete, where 1 is a mixer, 2 is a mixer cover, 3 is a mixer body, 4 is a trolley, 5 is a drain pipe, 6 is a rotor drive, 7 is an air duct, 8 is a control panel , 9 - high pressure valve of the gas pressure reducer, 10 - low pressure valve of the gas pressure reducer, 11 and 12 - low and high pressure drain valves, 13 - bypass valve, 14 - pressure gauge.

Figure 2 shows the layout of the grooves along the end of the rotor, where 15 is a cone with a corrugated surface, 16 is a channel of the shaft, 17 is a slot, 18 is an elastic element, 19 is a through gap.

Installation for the preparation of foam concrete by aeration works as follows.

Cart 4 with the installation is brought to the place of work, and into the mixer 1 through the open cover 2 are loaded the ingredients determined in the technological process. After that, the lid is hermetically closed and the rotor shaft drive 15 is actuated by means of the control panel 8. The low pressure valve 10 of the gas reducer opens (valve 9 is closed), and low pressure compressed air enters the rotor shaft channel 16 through the air duct 7. After passing through the through slots 19, the air enters the internal cavity of the cone with the corrugated surface 15. Under the influence of air pressure, the elastic element 18 bends and opens the slots 17. Air from the cavity of the cone enters the mixer. The resulting air bubbles break from the surface of the rotor by a rotating stream of the prepared mixture and are evenly distributed in its volume. After the mixture is saturated with air bubbles, the excess air in the cavity of the mixer is vented to the atmosphere through the bypass valve 13. It is also possible to manually vent excess pressure by opening the drain valves 11 and 12. The pressure in the cavity of the mixer is controlled by a pressure gauge 14. The finished mixture under the influence of high pressure air supplied into the cavity of the mixer with valve 9 (with the valve 10 closed), through the drain pipe 5, the corrugated hose is fed to the destination.

Claims (1)

Installation for preparing foam concrete by aeration, including a bar mixer equipped with a rotor mounted on a shaft, a trolley, a drive, a control panel, instrumentation, a fitting for supplying compressed air to the bar mixer body, characterized in that the bar mixer rotor is made in the form of a hollow cone with corrugated a surface whose base rests on an elastic element with reversible deformation, and slots are made along the perimeter of the base of the cone, the rotor shaft being provided with a channel that communicates with the corrugated cone through the through slots.

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