DE19632666C1 - Foam concrete production - Google Patents

Abstract

In the preparation of an air pore concrete, the fresh concrete or mortar mixture (10) is fed continuously from a pump (12) through a carrier channel (13) to the delivery outlet (14) together with an added continuous feed of a stable foam stream (5) through an outlet (131) into the channel (13). The two streams are mixed together as they move through the following carrier channel (132). At the foam (5) outlet (131) into the channel (13), the fresh concrete/mortar (10) and the foam (5) are at the same pressure of 2-8 bar in their continuous flow together. Also claimed is an assembly with a pressure vessel (2) for a water/foaming agent mixture (22), and a feed (11-13) for the fresh concrete mixture (10). A mixing zone combines the flows of fresh concrete (10) and foam (5), which are carried together to the delivery outlet (14). The fresh concrete (10) is carried (13) from a continuous feed pump (12) to the delivery outlet (14). The vessel (2) for the water/foaming agent mixture (22) has a compressed air supply (3) and a pair of jets (43) to form the foam in an enclosed pressure zone at the start of the foam channel (44). The paired jets (43) are linked to the pressure vessel (2) by a branch pipe (21) at one side and to the compressor (3) for the compressed air supply through an air pipe (42) on the other side. The foam channel (44) ends at a junction (131) with the concrete feed channel (13) in a pressure-sealed fit, near the feed pump (12). The mixing zone (131, 132), to mix the fresh concrete (10) and foam (5) extends from the foam channel outlet (131) to the delivery outlet (14).

Description

The invention relates to a method and an apparatus for manufacturing of air-entrained concrete, using a water-cement mixture with silicate Admixtures a foam consisting of water, foaming agent and air added and applied in a prepared position after a mixing process will.

DE 23 48 915 A1 describes a method and an apparatus for Production of a so-called air entrained concrete has become known. After this In the process, water is first mixed with a foaming agent and with Pumped into the mixing system with the aid of a piston pump. Promotes in parallel a second pump air in the same room of the mixing plant. Under application In the absence of air, a foam forms which is spread over a hose of the Feed position for the water-cement mixture is approaching.  

At the beginning of this mixing zone, the foam-guiding tube becomes coaxial the fresh concrete flow is introduced centrally, so that the foam the mortar encloses in a ring. In a subsequent, long, twisted hose the mixture of foam and fresh concrete thus formed is to be mixed further and be promoted.

The changes in direction of the hose and spiral beads on the The inner wall of the hose is intended on the one hand for a backflow of the mortar with foam and on the other hand for a good mixing of the mortar with worry about the foam.

Such a procedure can practically not lead to success. Because the mortar and the prepared foam are pulsating are fed and the resistance in the hose is very high the mixture of the foam with the fresh concrete or mortar mixture Air displaced from the foam and in the form of large air bubbles on the Inner wall of the hose collected. These big air bubbles are up carried to the discharge and go unused outdoors.

The resistance of the fresh concrete mix in the described hose ensures also for the fact that the fresh concrete is also in the foam formation zone spreads. Foaming is interrupted. The device is radio unable to function.

The air bubbles are therefore not regularly arranged inside the concrete net. The density of the concrete is very different. The inclusion of air in the The pores in the concrete are small.  

DE 27 18 918 A1 is a further modification of the described Procedure became known. With this method you also have that Water-foam mix with air under high pressure into one Foam processed. A foam with higher resistance was expected ability.

This foam was fed via pipes to containers in which the fresh concrete or mortar mixture was.

With the help of a mixer, the foam was mixed into the freshness concrete or mortar mixture. This foam-concrete mix was in temporarily stored in a tank and by means of a screw conveyor pump pumped to the destination via a hose.

Even with this procedure, the desired results were not achieved nits. The foam did not become so stable that the mixing process with the Fresh concrete protruded using a mechanical mixer.

The results were insufficient.

Another modified procedure is described in DE 31 32 667 A1 described. One released under the pressure of the usual water pipe Foam is added to the water jet before adding to this mixture air is pressed under the pressure of about 1.4 bar. The then in an expanding room, the so-called. Foam lance, under pressure reducing foam is then at normal pressure in the premixed building material distributed using a mixer.  

This presentation also addresses the mixing of fresh concrete and foam in a delivery line with a spiral internal structure. A is such a mixing process with foam provided under normal pressure but supposedly only possible if foam and fresh concrete are combined Container premixed, sucked in by a pump and through the conveyor tion are pressed. Only in these circumstances is in the delivery line appropriate mixing is possible.

However, as already described above, it is not possible under these conditions foam and fresh concrete to mix without the Foam is destroyed from the outset. This procedure is also included unusable.

One application of the method described in DE 23 48 915 A1 is but not possible because the fresh concrete is pumped into the Lance would penetrate. Foaming is interrupted immediately. The The device would be inoperable.

Such a procedure is therefore not applicable.

With the CH 657 844 A5, a method and a device for Production of a foamed mixture proposed, in which in a only mechanical mixer with agitator one after the other dry binders and the aggregates, then water and finally a prepared foam is fed.

Such a way of working is not suitable to solve the problem because of a Much of the foam touches it arbitrarily and strongly  moving concrete sludge is destroyed. The air escapes in large bubbles either back into the foam container or first into the mixture and then in the subsequent collector in the area.

Another disadvantage of this procedure is that the mixing of the Fresh concrete and the application of foam in a single operation he follows.

Is the concrete mixed, as usual, at a central station and then transported to the construction site by means of a transport mixer, then must at Applying this procedure automatically also involves a significant amount of air be transported. This means that valuable transport space is lost.

According to a further procedure disclosed by DE 38 07 250 A1 a concrete slurry is pumped into a continuous mixer. In these Continuous mixer also becomes a specially prepared one, with polymers Stabilized foam injected directly using an injection device. The Zem the sludge and the stabilized foam are then carefully added to the conti mixed mixer. The mixture obtained in this way is then intended for Deposit ready.

This way of working is also unsuitable, the problem in a satisfactory manner to solve. It is not possible to make the air-entrained concrete special without it stabilized foam.

The injection device, which is not described in detail, must Promote pressure without pressure and obviously  bring under pressure into the continuous mixer. It is not with one stabilized foam impossible. As a rule, the structure of the Foam is lost and the concrete supplied under pressure makes the injection establishment ineffective.

On the other hand, the use of a stabilized foam requires additional chen material expenditure and complicates the entire process.

The finished mixture is unsatisfied because of the size of the resulting cells with regard to the compressive strength that can be achieved. The area of application this cellular or cellular concrete is limited.

With the aim of increasing the number of pores in the concrete and the specific To reduce density, foaming agents were subsequently used, which in Connection with the water and the cement release gases that build up settle like pores inside the fresh concrete and the porous structure formed.

The disadvantage of this modification of the method is that the chemical Reaction to form the gases took a long time.

The productivity of the production of gas concrete - that's what they called it now Product - was accordingly low.

Because of the relatively quick hardening of the fresh concrete, regular use was possible only small portions can be made one after the other without interruption.

Another disadvantage is that the gas that forms is in most cases Contained hydrogen or hydrogen compounds that are harmful to health are. The use of such building materials was therefore in the interior of Buildings excluded.  

As a result, the focus was on the preferential chemical reaction Rende, gas-forming foam agents evenly in the fresh concrete mixture to distribute.

With DE 34 08 007 A1, one has initially switched to the Spray nozzle to mix the dry cement with a foaming agent, then add water and air and after a short mixing stretch the mixture of fresh concrete within the nozzle arrangement, To complete foam and water.

Such a process was without the use of chemically reactive foam medium not practicable at all. For its realization, it required that the gas formed was present before the time when the Fresh concrete mix was still capable of blistering. The blistering was only carried out regularly in the form in which the fresh concrete was to harden.

Problems regarding dimensional accuracy, the stability of the shapes and before everything regarding the stress distribution in the finished building material Limits. The mixing was insufficient and the one produced with it Product had cracks and irregular strength properties. At the end there was also only a gas concrete, its area of application, as above described, is limited.

DE 34 15 782 A1 discloses a second method of this type. It dry cement and foaming agent were first mixed mechanically. This was achieved by adding water and air under normal pressure  Mix in a second mixer, which is mechanically mixed with water and water Should bring air into the present mixture.

This system has also not proven itself. The second mechanical Mixer was unable to inject air particles into the mortar and to store as bubbles.

According to EP 517 207 A1, a sand-free cement-water mixture was used first the foam agent within a compact nozzle arrangement injected and after a very short mixing distance the Ge thus produced mixed air fed under high pressure. A pump should do this with air Promote enriched mixture to the order item.

This process also did not lead to the desired success. The genesis and distribution of the air pores was very differentiated.

In order to ensure a reasonably acceptable reliability, a very low viscosity water-cement mixture with a mixing ratio 1: 1. At such a ratio, only about 70% of the water chemically set. The remaining water must evaporate.

This caused the drying process to take a long time. The abrasion resistance and the compressive strength are unsatisfactory. Cracks could not be avoided. To ensure adequate Stability was forced to surface with a normal freshness to cover concrete or mortar layer, which then the manufactured element should give better properties.  

Another crucial disadvantage was that the air pore cement This type of mixture is only processed horizontally due to the thin liquid could be. Application on vertical surfaces or processing overhead was completely impossible.

Another device of this type is known from DE 40 41 727 A1. After dry mixing of binders, aggregates and foam Water is first added to the agent and the mixing process at high Mechanically continued speed. Air is only integrated in the small dimensions and is purely coincidental. A subsequent thick matter pump delivers the fresh mortar with the foaming agent. After the discharge port this Pump, the necessary, remaining water is supplied under high pressure. With this procedure, gas pores are only created by the released Reaction product of the foaming agent formed and filled.

In practice, this series of failures has led to rules moderate, as already mentioned above, as foam-forming elements or agents chose such substances that released corresponding gases chemically ten, which then often in the form during curing the pore formation realized.

The disadvantages in terms of productivity, damage to health and dimensional accuracy in at least one geometric size - as above described - one accepted knowingly.  

The present invention has set itself the task with simple With a prepared foam into a cement-water-sand mixture - in a fresh concrete - to bring in that a large number of air pores - if possible without support from chemical Operations - can be evenly distributed.

In particular, it should be ensured that the wall structures of the show mes are essentially retained during the mixing process and by the fresh concrete elements are reinforced.

It is imperative to avoid having the walls of the vesicles before their on bond in the concrete and the air in large bubbles uncon trolls escapes.

According to the invention, this object is achieved by the method features of the 1st Claim solved in a surprisingly simple way.

In the essentially continuous stream of fresh concrete is on the way also continuously to the discharge nozzle in the mouth of the delivery line A stabilized foam above the fresh concrete or mortar current under a defined, high pressure.

The thin components of fresh concrete or mortar penetrate the effect of cohesive and adhesive forces (capillary effect) and the high pressure in the walls of the foam bubbles. The bubbles are stabilized and the air trapped inside remains in the structured structure preserved (suction phase).  

The walls of the vesicles continue to stabilize and the aspiration of the Pore walls of the foam, with other parts of the fresh concrete or Connecting mortar improves.

The then increasingly effective cohesive forces are significantly larger than the previously effective adhesive forces. More and more part The fresh concrete is stored in the walls. Now kick z. B. sharp-edged grains of sand burst into the bubbles, they burst, but they do Air can no longer escape, but forms because of the larger upper surface tension levels of the walls and because of the preserved structure of the Foam a larger number of significantly smaller bubbles.

During the subsequent mixing process within the further one These air pockets are distributed through the pipe or hose in the fresh concrete evenly.

Additional elements of the fresh concrete are specifically stored during the mixing process the spaces between the vesicles.

This mixing process can now also be carried out using purely mechanical means, since the vesicle walls are stabilized so far that they start the mixing process survive undamaged.

The smaller bubbles lead to a higher stability of the building material without reduce the total amount of air entrapment. The bubbles will so small that they are barely visible to the naked eye.

However, the measured density proves the still high proportion of air.  

Experiments have confirmed that an air-entrained concrete can be produced by this method, the density of which can be set between 1.8 and 0.5 kp / dm ³ depending on the pressure conditions in the mixing zone and the amount of foam supplied.

Normally, this process becomes flowable to pumpable Consistency of the fresh concrete mix with a grain size of 0 to 2 mm used. The liquid fresh concrete foam mixture is reliable horizontal surfaces can be processed.

In a somewhat stiffer consistency, this mixture can also be used as a plaster Apply vertical surfaces and overhead.

The stability of the air-entrained concrete is sufficiently high. He has a good one Abrasion resistance.

The components cast from this air-entrained concrete either on site or the building blocks, plates, beams produced in a stationary system or the like can be machined using known working elements (Drilling, milling, sawing).

Otherwise, at least all users can use this air-entrained concrete areas that have been realized with gas concrete so far.

The air enclosed in the air-entrained concrete is not harmful to health enough. The building materials can thus also be used inside rooms be in which people are constantly or regularly over long periods of time stop rooms.

The air-entrained concrete produced in this way is highly recyclable.  

The recovered material can be shredded mechanically Process raw materials again into building materials in new forms.

Very positive results can be achieved using the given method visibly the trapped air when merging foam and fresh concrete is carried out at 4 to 6 bar.

It has been shown that a particularly effective way of working then can be guaranteed if - according to claim 2 - the foam on the over a supply to a cross-sectional expansion of the delivery line is supplied.

To ensure the necessary pressure in the mouth section of the foam, with simultaneous discharge capacity of the fresh concrete foam mixture the line for the fresh foam concrete between the mouth section and the discharge nozzle according to claim 3, so that the in this Resistance to overcome the necessary pressure in the section Muzzle section corresponds.

This pressure can be adjustable by either means of change the length or means of changing the cross-sections in the conveyor section are arranged.

To improve the transition from liquid components of the Fresh concrete mix in the walls of the foam bubbles is recommended in Area of the mouth section temporarily the fresh concrete flow on a to lead wider area and also ver  Apply the foam under pressure to a larger surface.

This design of the mouth section allows, even at higher Discharge speeds, a high quality of air-entrained concrete range (claim 4).

With regard to an optimal design of the strength of the air-entrained concrete and its crack free training will have very positive results from the Composition achieved according to claim 6. This proportion of water will almost completely chemical together with the water content of the foam bound. The proportion of water that has to be eliminated by evaporation is kept to a minimum.

With the addition of a foaming agent to the fresh concrete mix schung - according to claim 7, the results in terms of number, Size and amount of air inclusions in the air entrained concrete additionally ver be improved.

The formation of the foam according to the method of claim 8, made possible light it, the foam under the conditions of the necessarily high To produce pressure and the same under this pressure in the mouth bring section.

Extending the length of time the foam stays in the area between the Combining air and water with foam and the coin section according to claim 9 leads to a stable foam, the starting point for an even distribution of air in the fresh Is foam concrete.  

The device defined in claims 10 and 11 is suitable in be special way to produce a fresh concrete foam mixture for the Air-entrained concrete.

The device according to claim 12 shows means enabling the Produce foam on site with the least technical effort and under to bring a desired pressure into the mouth section.

The formation of the foam line according to claim 13 ensures a reliable stable formation of the foam with simple means. A Hose clamp works in the same sense.

It has proven to be useful to continuously feed the To ensure fresh concrete with the help of a vane pump. Such Pump is optimal when using the usual raw materials. You can with high efficiency generate the necessary pressure and secure immediately timely almost continuous promotion of fresh concrete (claim 14).

In the case of stationary systems in particular, the fresh can be fed concrete under appropriate pressure also via a sloping concrete pipe reach from a collection container with the appropriate fill level.

An optimal mixing of foam and fresh concrete is guaranteed when the fresh concrete delivery line is in the area of the Mün extension section is expanded by about 40% (claim 15).

On the one hand, thorough mixing of the fresh concrete and foam mixture on the other hand, an optimal way of working on site or in one place for the Manufacturing of individual components is guaranteed if, according to claim 16, as a mixing zone between the mouth section and the discharge nozzle  a flexible hose with a length of 5 to 15 meters is provided, whose inside diameter is about 60 mm.

An optimal way of working on site is described by the arrangement of the benen device on a mobile device in the version according to An Proof 17 guaranteed.

The invention will be explained in more detail below using an exemplary embodiment will. In the accompanying drawings:

Fig. 1 is a schematic illustration of the overall plant for the realization of the method according to the invention,

Fig. 2 is an enlarged schematic representation of the mouth portion in a side view;

Fig. 3 is a view of the mouth portion in a schematic view from above,

Fig. 4 is a side view of a mobile station for the production of the fresh concrete-foam mixture and

Fig. 5 is a plan view of Fig. 4.

The fresh concrete 10 or mortar is generally brought to the processing site via a transport mixer, not shown, where it is temporarily stored in a funnel-shaped container 11 and fed to further processing by means of a pump 12 .

In the conveyor line 13 for the fresh concrete 10, which leads from the pump 12 to the discharge nozzle 14, in the flow direction initially, the mouth portion 131 is arranged and at the end, after the conveying section 132, the discharge nozzle attached fourteenth

A foam line 44 for a prepared foam 5 , which is to be inserted into the fresh concrete 10 , opens into the mouth section 131 from above.

After the mouth of this foam line 44 , the delivery line 13 for the fresh concrete 10 is expanded in this case and is from here, preferably with this expanded cross section, to the discharge nozzle 14 .

This conveying section 132 serves both to transport the mixture and to intensively mix the constituents of the mixture.

With its internal frictional resistance, it also secures the pressure required for the mixing process in the mouth section 131 .

For the production of the foam 5 under a high pressure, this device has a pressure vessel 2 , which contains a larger amount of water (about 150 l), which is mixed 22 with a foaming agent (1-2% of the amount of water).

Proteins are expediently used as foaming agents.

A compressor 3 maintains a pressure of 2 to 6 bar in this pressure vessel 2 via the pressure line 41 . The pressure is adjustable by means of throttle valve 412 and check valve 411 .

The pressure vessel 2 has a riser pipe 21 leading to a pair of nozzles 43 , which can optionally act as an injector or ejector.

The throttle valve 412 and the check valve 411 can optionally also be assigned to this riser pipe 21 .

This riser pipe 21 opens into a pressure line 42 in which the foam formation 5 is triggered on the pair of nozzles 43 .

This foam 5 stabilizes and evens out within the foam line 44 . The internal frictional resistance in the foam line 44 acts as a support. A very stable and uniform foam 5 is achieved if the foam line 44 is designed as a flexible, sinuous hose with a length of about 10 m.

It is possible to work with a shorter hose and to generate part of the frictional resistance by means of an adjustable throttle valve 442 .

The stable and uniform foam 5 thus produced is positively pressed into the mouth section 131 under pressure.

The air led to the pair of nozzles 43 is compressed with the aid of the compressor 3 . The pressure in the pressure line 42 is adjustable via the adjustable throttle valve 422 and the check valve 421 .

The pressure there depends on the pressure in the riser pipe 21 .

It should be at least 2 bar, but preferably up to 6 bar.

The mutual adjustment of the pressure in the riser pipe 21 to the pressure in the pressure line 42 depends on the effect with regard to the foam formation. The pair of nozzles 43 can work both as an injector and as an ejector.

At the selected pressure conditions, a foam 5 is formed immediately behind the nozzle pair 43 under pressure, which is stabilized via the subsequent foam line 44 and continuously reaches the mouth section 131 under the existing pressure.

The pump 12 described above also delivers the fresh concrete 10 continuously at a speed of 1 to 2 m / s and an adjustable pressure of likewise 2 to 6 bar into the mouth section 131 .

In the mouth section 131 , the cross section of the fresh concrete line 13 expands, preferably gradually, by about 40% or by the cross section of the foam line 44 opening there.

In the mouth section 131 , the pressure generated by the pump 12 and by the compressor 3 is secured by the internal frictional resistance of the subsequent delivery section 132 , which extends to the discharge nozzle 14 and is designed as a hose.

The length of this conveyor section 132 or hose and its cross section ensure that the resistance of the fresh concrete foam mixture 54 , which is located in the hose, withstands the pressure in the mouth section 131 and still allows the flow of this mixture 54 .

The consistency of the fresh concrete 10 supplied is preferably fluid to pumpable. Fresh concrete 10 , category KF according to DIN 1045, has proven particularly useful. Under certain circumstances, fresh concrete with pumpable consistency (KR) can also be used.

The use of sand with a grain size of 0 has proven to be essential up to 2 mm.

In the area of the mouth section 131 there is a high probability that a process is taking place which has not previously been considered in the manufacture of air-entrained concrete.

The stable and uniform foam 5 pressed under high pressure and low speed onto the fresh concrete 10 first sucks in the mouth section 131 the liquid components of the fresh concrete mixture 10 , consisting of water, cement and dust-like sand, into the walls of the bubbles (foam in the suction phase 51 ).

The walls of these bubbles 51 are thereby reinforced and the molecular forces to the remaining fresh concrete mixture 10 change in a positive sense.

As a result, these bubbles 51 get deeper into the fresh concrete 10 while simultaneously stabilizing their walls and increasing the surface tension. The walls of the vesicles (foam in the first stabilization phase 52 ) become thicker.

The bubbles 52/53 which have been retained in their structure and the air contained in them thus remain within the fresh concrete 10 and are reliably enclosed there.

The further increase in the surface tension acts in conjunction with the grains of sand contained in the fresh concrete 10 in the sense that the foam bubbles now divide within the fresh concrete (foam in the second stabilization phase 53 ) and form smaller pores there.

The so enclosed in the fresh concrete 10 , stable, small air bubbles 54 are evenly distributed in the following conveying section 132 to the discharge nozzle 14 by the turbulent flows occurring there, without their air content being expelled from the fresh concrete-foam mixture.

As a rule, the bubbles are further divided during this process. An almost homogeneous fresh concrete / foam mixture 54 with a high proportion of air is created. The air bubbles can become so small that they are no longer visible to the naked eye in the finished, hardened mixture. However, their actual presence is confirmed when the density is determined.

It is also noticeable through the on-site apparent growth in the volume of fresh foam concrete 53 compared to the fresh concrete 10 used .

In this phase, the fresh foam concrete 54 can also be exposed to intensive mechanical loads. It is pumpable.

It can be mixed mechanically again. It is also possible to densel can be applied as plaster and the applied layer in conventional Way to rub.

Almost all components of this mixture 54 serve to harden the mixture. Excess water, which is usually only added to the fresh concrete 10 within normal tolerances in an amount of 40 to 50% of the cement portion (weight) and then supplemented by the water of the foam 5 , does not have to be eliminated by evaporation. Long drying times and cracking are avoided.

The air-entrained concrete produced in this way has a high strength. The abrasion Strength is given in such a quality that it is on walls and Floors withstands the normal loads occurring there.

To illustrate the mixing process of fresh concrete 10 and foam 5 , FIG. 2 shows a side view of the mouth section 131 . The För derleitung 13 affects the further expanded pipe section in the region of the mouth portion 131th

The cross section of the expanded pipe section is almost twice as large as the cross section of the incoming delivery line 13 for the fresh concrete 10 . The foam line 44 opens out over the delivery line 13 .

The foam 5 is under approximately the same pressure as the fresh concrete 10 supplied. It is not possible for fresh concrete 10 to penetrate into the foam line 44 .

In this arrangement, the foam 5 lies on the fresh concrete 10 and fills the larger free space up to where - due to the pressure balance - the fresh concrete-foam mixture 53/54 fills the cross section of the further hose or conveying section 132 .

Due to the high pressure of the foam 5 , the foam walls with the fresh concrete 10 are intensively touched.

The low-viscosity components of this mixture instantly get into the foam walls and thus create the conditions for a good mixing of foam 5 and fresh concrete 10 - as described above.

In this process, the penetration of liquid components of the fresh concrete 10 into the foam walls can be optimized by increasing the surface of the fresh concrete 10 in the area of the foam feed.

This is possible by making the cross section flatter in the mouth section 131 . The then wide-running fresh concrete 10 offers the foam 5 a larger contact surface. Mixing improves.

It is understood that the pressure of the foam 5 must be adjusted accordingly.

Adjustment processes are easier if transparent, possibly translucent components are inserted in the mouth section 131 , which allow the boundary between foam 5 and fresh concrete to be recognized under the conditions of the current pressure.

To keep the mouth section 131 formed in this way , it is expedient to design this section with feeds for the fresh concrete 10 and the foam 5 so that it can be cleaned independently of other construction elements also inside.

For this purpose, this section consists of two in a manner known per se Parts made that are detachably connected by screws.

In the lower part, the fresh concrete 10 flows regularly and in the upper section, only the foam 5 is initially guided.

Instead of the commonly used fresh concrete 10 , of course, as usual, mortar can be used, the other additives, such as. B. lime.

Taking into account the basic teaching described, substances other than fresh concrete 10 can also be used. The only condition is that the binder used in conjunction with a liquid that can also mix with foaming agents cures to a solid material.

In those cases in which a particularly high proportion of air bubbles in the air-entrained concrete is to be achieved, it is expedient to add foam agent to the fresh concrete 10 already during its production and to distribute the same evenly therein.

The surface tension of the liquid components of the fresh concrete mixture 10 is thereby increased from the outset. In the phase of merging, the process of air inclusion can be additionally stabilized. In parallel, it is advisable to increase the pressure in the system 4 for the foam production.

With the larger amount of foam 5 , more air is also provided for introduction into the fresh concrete 10 .

This process can be done using the actuating means 411 , 412 ; 421 , 422 in the supply lines 41 , 42 between compressor 3 and pair of nozzles 43 and between compressor 3 and pressure vessel 2 in a simple manner.

The cross-sectional enlargement in the area of the mouth section 131 is expedient, but not in principle conditional. It is also possible to keep the cross section of the delivery line 13 after the mouth of the foam line 44 in the same size. Due to the same high pressure in both lines, mixing takes place in the same way as described above.

The resulting larger volume creates space through an increased discharge rate of the fresh foam concrete 53 in the conveying section 132 .

The use of such a system is both on site on construction sites also in a stationary system for the production of building blocks, carriers or wall elements possible.

For use on construction sites, on site, it is expedient to install the units required for the production of the air-entrained concrete on a mobile unit, an equipment trolley 6 .

This mobile equipment trolley 6 is shown in simplified form in FIGS. 4 and 5.

It has a pump 12 , which is preferably designed as a vane pump.

This pump 12 is assigned a funnel-shaped container 11 into which the transport mixer unloads the fresh concrete 10 .

In addition to this pump 12, there is the pressure vessel 2 , which are assigned to lines 41 , 42 , the compressor 3 and the pair of nozzles 43 for foam formation.

Both units 12 and 3 convey their media, the fresh concrete 10 or the foam 5 , under pressure into the mouth section 131 .

At the mouth section 131 , the flexible hose then connects as a conveying section 132 , which is equipped at its end with the discharge nozzle 14 .

Parallel to this latter hose, a second pressure hose 45 can be guided, which additionally guides air compressed by the compressor 3 into the area of the discharge nozzle 14 and in turn supports the discharge of the mixture 53 .

This equipment trolley 6 is also usually equipped with a hose carrier 61 and with an electrical control unit 62 . The control unit 62 is preferably located near the container 11 , near the mouth section 131 and close to the actuating means of the throttle valves 412 , 422 , 442 .

Given the good achievable strength properties of this Such a system is suitable for air-entrained concrete also for high quality, professional at a central manufacturing facility Manufactured blocks from this material.

These components can be mechanically loaded using standard tools work and adapt to the given conditions at the construction site.

In the same way you can of course also individual bars or complete Manufacture wall elements from this material centrally and adapt them on site and assemble.

If you add fine sand to the fresh foam concrete 54 , it is also possible to plaster vertical walls or ceilings with this raw material. Such plaster increases the thermal insulation of a wall, on the one hand, and on the other hand, such a layer guarantees the breathability of the wall.

Due to the high smudge resistance and the high stability of the air-entrained concrete overall, this material offers a real alternative for the renovation of Old buildings.

The in many places controversial renovation by the application of synthetic Foam layers and their protection by fabrics and plaster layers, can be replaced by the air-entrained concrete as a building and cleaning material.

Because of the better properties of this material in terms of its Strength, its tolerance for humans in normal condition and at Fires can also be used indoors without hesitation.

Outside, you can also use chemical gas-generating Foam agent has larger pores and thus a higher thermal insulation value achieve a lower density.

Reference list

Fresh concrete feed

10th

Fresh concrete

11

container

12th

pump

13

Conveyor line

131

Mouth section

132

Conveyor section (with mixed function)

14

Discharge nozzle

141

Compressed air supply

2nd

pressure vessel

21

Riser pipe

22

Water-foam compound

3rd

compressor

4th

Foam forming unit (system)

41

Pressure line (e.g. pressure accumulator)

411

check valve

412

Throttle valve, adjustable

42

Pressure line (also jet line)

421

check valve

422

Throttle valve, adjustable

43

Pair of nozzles

44

Foam line

442

Throttle valve, adjustable

45

pressure hose

5

foam

51

Foam in the suction phase (bubbles) (slightly liquid parts of the fresh concrete are sucked up)

52

Foam in the first stabilization phase (heavier parts of the fresh concrete are sucked up - air is enclosed in stable bubbles)

53

Foam in the second stabilization phase (bubbles are divided by granular components of the mixture, several small bubbles form)

54

Fresh concrete-foam mixture (the stable, small bubbles are evenly distributed in the fresh concrete)

6

Equipment cart

61

Hose carrier

62

Control unit.

Claims (17)

1. Process for the production of air-entrained concrete, wherein

• - A fresh concrete or mortar mixture with silicate admixtures
• a foam consisting of water, foaming agent and air is added and discharged in a prepared position after a mixing process,
  characterized in that a fresh concrete or mortar mixture ( 10 )
• - Between a continuously conveying pump ( 12 ) and a discharge nozzle ( 14 ) of a delivery line ( 13 ) at a mouth section ( 131 ), a stable foam stream ( 5 ) is fed continuously and
• - is mixed with the fresh concrete ( 10 ) during the conveying in a subsequent conveying section ( 132 ),
• - The fresh concrete or mortar mixture ( 10 ) and the foam ( 5 ) in the mouth section ( 131 ) are brought together under the same pressure between 2 and 8 bar continuously flowing.

2. The method according to claim 1, characterized in that the foam stream ( 5 ) to the fresh concrete ( 10 ) at the transition to a cross-sectional expansion of the delivery line ( 13 ) is fed continuously. 3. The method according to claim 1 or 2, characterized in that the flow of the fresh concrete-foam mixture ( 53/54 ) after the merge via a conveyor section ( 132 ) in a line in which the sum of the frictional resistances to builds up a resistance to the discharge nozzle ( 14 ), which secures the pressure in the mouth section ( 131 ). 4. The method according to claim 1 to 3, characterized in that the stable foam stream ( 5 ) fed at a pressure of at least 2 bar and in a subsequent, at least 5 m, preferably up to 15 m long conveyor section ( 132 ) with the fresh concrete ( 10 ) is mixed during conveying. 5. The method according to claim 1 to 4, characterized in that the fresh concrete mixture ( 10 ) has a flowable to pumpable consistency. 6. The method according to claim 1 to 5, characterized in that the fresh concrete mixture ( 10 ) has a water content of 40 to 50% of the mass of the cement portion. 7. The method according to claim 1 to 5, characterized in that the fresh concrete mixture ( 10 ) before the combination with the foam ( 5 ) additionally gas-forming foaming agents are added evenly distributed. 8. The method according to claim 1 to 7, characterized in that the foam ( 5 ) by means of free rectified, mutually adjacent jets of air and a water-foam mixture ( 22 ) under an adjustable pressure in a closed space between two and eight bar is generated by means of a pair of nozzles ( 43 ). 9. The method according to claim 1 to 8, characterized in that the foam ( 5 ) between the pair of nozzles ( 43 ) and the mouth section ( 131 ) under pressure in a limited, elongated space, the foam line ( 44 ), via a defined Period is stabilized and promoted. 10. Device for the production of air-entrained concrete according to the method of claim 1, consisting of

• - a pressure vessel ( 2 ) for a water-foam mixture ( 22 ),
• - a foaming unit ( 4 ) with feeds ( 42 , 21 ) for compressed air and a water-foam mixture ( 22 ),
• - A feed ( 11 , 12 , 13 ) for a fresh concrete mixture ( 10 ),
• a mixing zone for combining fresh concrete ( 10 ) and foam ( 5 ) and a fresh concrete delivery line ( 13 ) from the mixing zone to the discharge nozzle ( 14 ),
  characterized,
  that the fresh concrete delivery line ( 13 ) extends from a continuously conveying feed pump ( 12 ) for the fresh concrete ( 10 ) to the discharge nozzle ( 14 ),
  that a compressed air source ( 3 ) is assigned to the pressure container ( 2 ) for the water-foam mixture ( 22 ),
  that a pair of nozzles ( 43 ) is provided in a closed pressure chamber, at the beginning of the foam line ( 44 ), for foam formation,
  that the pair of nozzles ( 43 ) is connected on the one hand via a riser pipe ( 21 ) to the pressure vessel ( 2 ) and on the other hand to a pressure line ( 42 ) for the compressed air fed by a compressor ( 3 ),
  that the foam line ( 44 ) opens close to the feed pump ( 12 ) at the mouth section ( 131 ) in the fresh concrete delivery line ( 13 ), and
  that the mixing zone ( 131 , 132 ) for combining fresh concrete ( 10 ) and foam ( 5 ) in the fresh concrete delivery line ( 13 ) from the mouth section ( 131 ) to the discharge nozzle ( 14 ).

11. The device according to claim 10, characterized in that the total cross section of the delivery line in the area of the Mündungsab section ( 131 ) corresponds approximately to the sum of the cross sections of the feed lines of the fresh concrete ( 10 ) and the foam ( 5 ). 12. The apparatus of claim 10 and 11, characterized in that the compressor ( 3 ) for foam formation

• - A pressure line ( 41 ) to the pressure vessel ( 2 ), which feeds the water-foam mixture ( 22 ) to the pair of nozzles ( 43 ) via the riser ( 21 ), and
• - A pressure line ( 42 ) for the compressed air is assigned directly to the pair of nozzles ( 43 ) and
  that a check valve ( 411 , 421 ) and an adjustable throttle valve ( 412 , 422 ) are arranged in each of the two pressure lines ( 41/21 , 42 ).

13. The apparatus of claim 10 to 12, characterized in that the foam line ( 44 ) is designed as a flexible pressure hose with a length of 4 to 10 m. 14. The apparatus according to claim 10 to 13, characterized in that the continuously feeding pump ( 12 ) for the fresh concrete ( 10 ) is a vane pump. 15. The apparatus according to claim 10 to 14, characterized in that in the fresh concrete line ( 13 ) subsequent to the mouth section ( 131 ) a cross-sectional expansion of at least 40% is provided. 16. The apparatus according to claim 10 to 15, characterized in that the mixing zone adjoining the mouth section ( 131 ) is designed as a tubular conveying section ( 132 ) of the conveying line ( 13 ) which has a length of between 5 and 15 meters and an inside diameter of about 6 cm. 17. The apparatus according to claim 10 to 16, characterized in that on a mobile equipment trolley ( 6 )

• - The pressure vessel ( 2 ) for the water-foam mixture ( 22 )
• - the compressor ( 3 ) for foam production,
• - The pump ( 12 ) with container ( 11 ) for the fresh concrete ( 10 ),
• - The delivery line ( 13 ) for the fresh concrete with the mouth section ( 131 ),
• - Adjustable throttle valves for the water, air, foam and fresh concrete feed as well
• - A control unit for motors and / or valves are arranged.