DE3218159A1 - Method for spraying wet concrete and preparation chamber for wet-concrete spraying machines - Google Patents

Abstract

A method and an apparatus are to be provided, which allow wet concrete to be sprayed continuously and effortlessly under optimal conditions, even with regard to the quality of the sprayed concrete. For this purpose, the discontinuously produced concrete is processed to form a substantially continuous concrete stream. This concrete stream is fed to a pneumatic, at least approximately continuously operating conveying machine. Said processing consists in converting the concrete, which is produced in batches, by vibration into a continuous concrete stream. This is carried out in a preparation chamber having a concrete feeding pipe (3) and a conveying air feeding pipe (13). An unbalance vibrator (16) vibrates the concrete on a distributing floor (32) into an almost continuous, almost stationary concrete stream. The floor of the chamber (4) forms part of a cascade, a nozzle plate (36) impinged by compressed air being provided in the progressive ratio. The emerging compressed-air jets take hold of the concrete stream falling over the cascade, accelerate it and transport it pneumatically. <IMAGE>

Description

Process for spraying wet concrete and precast

Preparation chamber for wet concrete spraying systems The present invention relates to a method for spraying wet concrete, in which the concrete is first discontinuously and then pneumatically using compressed air as well as a preparation chamber for wet concrete spraying systems, with at least one Concrete feed and at least one conveying air feed.

In the wet spray process, there are basically two known ones Methods that have not yet made a breakthrough.

The flight conveyor method consists in that the precast concrete by means of Flight conveyance is transported through pipes or hoses to the spray nozzle.

This process has the following disadvantages: Risk of segregation during transport over long distances - no large conveying distances possible - knocking delivery hoses, risk of clogging - high air consumption with high Pressure - high rebound of the concrete on the structure, as the concrete partially segregates emerges from the nozzle.

The wet spray flight conveyor method never caught on and is practically no longer used today.

The problems are: limited conveying distance, layer thickness only 2 - 3 cm per spray, insufficient adhesion on the surface and between the individual ones Shotcrete layers, high shrinkage, ultimate strength 2 at approx. 20 n / mm, water permeable.

In the pumped concrete wet spraying process, the concrete is through pipe and Hose lines conveyed by means of a screw or piston concrete pump and connected to the Spray nozzle split and accelerated by means of compressed air.

This method has the following disadvantages: - The compact concrete column is only broken up at the spray nozzle by the compressed air and meets in lumps the spray surface.

- The impact speed is approx. 7 - 12 m / sec.

It's way too small.

- The compression on the object is poor and does not correspond the requirements that are placed on shotcrete.

- The delivery hose is unwieldy because it is too heavy; the whole hose is filled with a compact concrete column up to the nozzle.

- The addition of setting accelerators is problematic because none perfect mixing with the concrete can take place.

- The application thickness is due to the low compression and adhesion limited to a few centimeters. Ueberkopf is a spray without a snap fastener not possible.

- The quality of the shotcrete does not meet the required values, especially in tunnel construction.

The now widespread and technically mastered dry concrete spraying process has the major disadvantage that a lot of dust develops when it is carried out becomes, which is not only very troublesome and uncomfortable for the operating personnel, but can also have harmful consequences for health. Therefore an attempt was made to replace the Dry concrete spraying process to carry out the wet concrete spraying process in which the finished sprayable concrete in bursts with a piston pump according to the number of pistons conveyed into a pneumatic feed device and in this, by the compressed air is taken over, pneumatically conveyed and sprayed. This procedure shows well does not have the mentioned disadvantage of dust formation, but is qualitative with the Dry spraying cannot be compared, as the pneumatic conveying as a result of the The concrete is also poured in batches. This is not just detrimental to the application of the concrete to the structure, but rather places the operating team especially the nozzle operator, very high demands, because of that intermittently Spraying of the concrete as a result of the intermittently changing momentum at this nozzle high Forces occur which are essentially absorbed by the nozzle operator have to.

The poor quality and the extremely troublesome, only by a lot Strong people withstandable, wet spraying therefore brought little fans of this type.

The present invention aims to provide a method and a device that allows wet concrete to be poured continuously without the aforementioned Cons to splash.

In this sense, the method according to the invention is characterized by this from that the discontinuously occurring concrete to an essentially continuous one Prepared concrete flow and this concrete flow the pneumatic, at least approximately continuously working, conveyor system feeds.

A preparation chamber, with which it is possible to do this in bursts to convert the delivered concrete mass into a continuous stream with the air, is characterized in that means are arranged to intermittently into the Chamber conveyed concrete in an at least approximately continuous concrete stream to transform.

The invention is then illustrated, for example, with the aid of a figure explained.

The figures show: FIG. 1 the diagram of a wet concrete spraying system like that in and of itself, with the exception of the preparatory chamber and its accessories, in the concrete wet spraying technique is known, Fig. 2 is a longitudinal section through a preparation chamber with a bearing block and connections, FIG. 3 shows a cross section by c ;. Preparation chamber according to line III - III of FIG. 4, FIG. 4 is a plan view on the preparation chamber according to FIG. 2, partially sectioned along the cutting lines IV - IV of FIG. 3.

A wet concrete spraying machine 1 is used for spraying concrete, which usually has a multiple piston pump. This conveys the wet concrete Depending on the number of pistons and the pump speed, intermittently through a concrete delivery pipe 3, which opens into a preparation chamber 4.

An air pressure generator (not shown) supplies the necessary compressed air through a compressed air line 6.

Part of this compressed air is used to feed a metering device 7, in which an additive is prepared from an additive container 9 through 1 Ed a delivery line 10 is pumped.

The compressed air coming from the compressed air line 6 is, as shown in Fig. 1 can be seen, fed to an upper air line 12 and a lower air line 13, both of which open into the preparation chamber 4, the upper air at the top, the lower air more in the lower front part of the chamber 4. Also through the compressed air line 6 fed, a compressed air line 15 leads to an eccentric vibrator here 16 trained vibrators. A control air line 18, the air pressure corresponds to the air pressure in a preparation chamber 19 of the preparation chamber 4, is used to control a vibrator compressed air control valve 21.

The preparation chamber 4 is followed by a pneumatic transport line 23, at the end of which there is a spray nozzle 24. From the compressed air line 6 is also branched off a metering compressed air line 25, which the pneumatic transport and admixing the additive is used. In Fig. 1 is also one with wet concrete Rock wall 26 to be sprayed can be seen, with concrete 27 previously sprayed.

If for wet concrete spraying the wet concrete spraying machine 1 and the compressed air generator are put into operation, the concrete enters the preparation chamber in bursts 4, where it is prepared in a way that has yet to be explained so that it, with upper and lower Under air mixed, enters the pneumatic transport line 23 and through this the spray nozzle 24 is fed. This stream becomes the glue-like in the spray nozzle 24 Admixtures, e.g. quick binders, added.

In the previously known systems, the concrete, which was pumped in bursts, was used brought together with the compressed air, so that as a result of the intermittent delivery of the concrete to the compressed air flow, the concrete in bursts, according to the pumping frequency and the number of pistons through which the spray nozzle 24 was sprayed and to the initially mentioned shortcomings.

With the aid of the preparation chamber shown in FIGS. 2-4 4 it is made possible to send an air-concrete mixture to the spray nozzle 24 in the form of a continuous Feed beam. As can be seen from Fig. 2, the upper air line 12 opens into an upper air nozzle 30, the front end of which forms a perforated nozzle plate 31. Through this, the compressed air flows into the processing chamber in individual jets 19. In this chamber 19, a distributor base 32 is arranged, which with the jacket the processing chamber 19 and is welded to a closing flange 35. This The bottom 32 and the jacket of the processing chamber 19 form an under-air chamber 34 fixed, the end of which is cascaded by an air nozzle segment plate 36 of the end flange 35 takes place. The design of this air nozzle segment plate 36 can be seen from FIG. 3. Here, too, the air fed into the lower air chamber 34 through the lower air line 13 Compressed air divided into individual air pressure jets. It is possible to have several cascades to switch one after the other. Instead of or in addition to the plate 36, a Part or a complete ring air nozzle can be arranged.

A cleaning water connection is located on top of the jacket of the processing chamber 19 38, which allows the pneumatic system to be flushed through at the end of a spraying process and clean.

The preparation chamber 4 is mounted on rubber swing blocks 39, which are attached to a carrier plate 40. This is at one end by means of a bracket 41 pivotally connected to an adjusting rod 42, the lower The end is fastened to the base frame 44 via a tab 43.

On the other hand, the support plate 40 is on a fixed strut 46 arranged in a bracket 47 so as to be pivotable about a bearing pin 48.

By adjusting the anchor rod 42, the pivot position the preparation chamber 4 can be adjusted with respect to a horizontal plane, whereby ach the inclination of the distributor base 32 is changed. This possibility of change is important as it is an adaptation of the position of the chamber 4 to the concrete mix and a possibility of influencing the pneumatic conveyance is allowed.

The base frame 44 with the entire superstructure stands on one side firmly on the ground. On the other hand, it has a pair of wheels 50, which allows to move the whole preparation chamber effortlessly. The preparation chamber is in operation 4 inclined so that an angle of inclination between the floor 32 and the horizontal from 0 to 250 is created.

As can also be seen from FIG. 2, the distributor base 32 also forms the preparation chamber longitudinal axis 52 a certain fixed angle, the installation angle of about 150, while the angle that the distributor base with a horizontal plane forms, can be adjusted by adjusting the tie rod 42.

To easily get into the interior of the preparation chamber 4 and in particular To get into the processing chamber 19 is that of the processing chamber 19 following Acceleration chamber 54 connected to the latter by means of a quick release flange 53. For this purpose, two eyelets 56 connected to the end flange engage through two horizontally arranged longitudinal holes of the quick-release flange 53, whereby by means of two wedges 57 the connection shown in FIG. 4 is established. When the two wedges 57 can be released, the acceleration chamber 54 with the quick release flange 53 around the axis 55 can be pivoted so that the processing chamber 19 is freely accessible as can be seen approximately in FIG. As a conclusion to the acceleration chamber 54, a connection flange 59 is provided for the pneumatic transport line 23. It is also possible to have an adjustable built-in part in the upper half of the chamber 54 to be provided (dash-dotted). Possibly then at least one part the upper air can be dispensed with.

Observations have shown that the essential point is when spraying wet concrete of the present invention in the following: The through the concrete delivery pipe 3 of the Wet concrete spraying machine 1 concrete mix delivered in batches arrives in batches into the processing chamber 19. Here, due to the eccentric vibrator 16, dividing and distributing the concrete, for which purpose the distributor base 32 is also used.

The vibrator 16 shown is a so-called eccentric or unbalance vibrators. In principle, however, it is also possible to use the preparatory chamber 4 to be provided with a so-called throwing vibrator, in which the movement is circular, as is the case with so-called shaking transports.

Due to the shaking movement, the concrete mix spreads at least approximately uniformly over the distributor plate 32 and falls, practically continuously, in front of the compressed air curtain, which is on the outlet side of the air nozzle segment plate 36 trains. The compressed air jets capture the already loosened concrete mix in flight and promote it in the acceleration chamber 54 against the connection flange 59 and into the pneumatic transport line 23.

The ready-to-use mixture is formed at the end of the acceleration chamber 54 and at the beginning of the line 23. These parts must be designed in this way and the amount of the pumped mixture as well as the pressure and the amount of conveying air must be coordinated so that in line 23 at the latest briefly before entering the spray nozzle 24, the mixture reaches the desired speed that is the speed it takes to actually produce high-quality wet shotcrete to create on a building part. It is 50 - 100 m / sec.

As the task of the concrete in the conveying air jets from the air nozzle segment plate 36 takes place practically continuously, the air-concrete mixture emerging from the nozzle 24 is also - h an essentially continuous jet, practically without impacts and interruptions. In this way it is possible to convert an intermittent concrete mix into a quasi to transform continuous stream formation. Whose task leads into the conveying air for the desired uniformity of the concrete spray jet from the nozzle 24.

To support this movement and the process, the compressed air jets serve which emerge from the perforated nozzle plate 31. They are used to help with processing of the concrete stream. In the acceleration chamber 54 they lead the lower conveying air stream with the concrete and help avoid that sub-air by vortexing the pneumatic Transport obstructed.

By storing the preparatory boxes 4 on the rubber swing blocks 39 it is ensured that the vibrator 16 uses its vibrating energy of the preparation chamber 4 fully feed and thus the distribution of the concrete to the distributor base 32 can achieve a steady stream of concrete.

Although it would in principle be possible to use the vibrator 16, for example to be driven electrically, the tests have shown that the arrangement shown it enables a kind of self-regulation to be achieved. If namely from any one reason the removal of the amount of concrete not caused by the Concrete delivery pipe 3 corresponds to the amount of concrete delivered in batches, can be in the Prepare processing chamber 19 a concrete mountain, which the flow cross-section for the upper air from the perforated nozzle plate 31 is reduced. This leads to, that the air pressure rises immediately after the perforated nozzle plate 31 and the Air speed increases. Since usually a positive air blower is used, which supplies constant air volumes, when the compressed air decrease takes place for driving the vibrator 16 from the upper air line 12, the amount of air rise to the vibrator and this emits an increased vibrating power. this in turn accelerates the breakdown of the concrete mountain in the processing chamber 19, so that this not only remains stationary, but is reduced until the air cross-section for the upper air in the processing chamber 19 has become larger again and the The vibrator performance decreases accordingly. That way is a self-regulation of the system possible.

Another possibility of regulation can be seen in FIG. 1, in which the pressure in the rear of the processing chamber 19 as the control pressure for the vibrator compressed air control valve 21 is used, from which as much air is taken through the compressed air line 15 to the vibrator 16 is that the processing chamber 19 is neither emptied nor filled up.

With the help of this preparation chamber 4, the new process can be carried out effortlessly and without any risk of clogging. The basic ones The proportions are evident from the true-to-scale FIGS. 2-4, while the absolute dimensions depend on the required performance of wet concrete.

The method described and the devices explained show compared to the previously known advantages including: - Achievement of practical unlimited conveying distances - high compaction, water impermeability and concrete quality, similar to dry shotcrete - practically dust-free operation - handling the spray nozzle as in the dry spray process - flawless quick-release binder supply into the solid-air mixture - easy, mobile installation of the concrete injection unit.

Wet concrete with a grain size of 30 mm can now be optimally sprayed

Claims (19)

Claims: 1. Method for spraying wet concrete, in which the concrete is first discontinuous and then pneumatically using compressed air promotes and injects, characterized in that the discontinuously occurring Concrete processed into a substantially continuous stream of concrete and this Concrete flow of the pneumatic, at least approximately continuously working conveyor system feeds. 2. The method, preferably according to at least one of the claims, characterized characterized in that the intermittently accruing concrete can be shaken into a continuous stream of concrete. 3. The method, preferably according to at least one of the claims, characterized characterized in that the intermittent concrete is treated in a chamber (4) and vibrates, whereby the vibration level is determined with a change in the static pressure changes in the feed section of the chamber, e.g. increased when the pressure is increased. 4. The method, preferably according to at least one of the claims, characterized marked that the concrete is already used before the actual flight delivery Treated compressed air. 5. The method, preferably according to at least one of the claims, characterized characterized in that the concrete flow is generated on a floor that is related to the Horizontal one falling Inclination angle between 0 and -250 having. 6. Preparation chamber for wet concrete spraying systems, with at least a concrete feed and at least one conveying air feed, characterized in that, that means (16, 32) are arranged in order to convey the intermittently into the chamber To transform concrete into an at least approximately continuous stream of concrete. 7. Preparation chamber, preferably according to at least one of the claims, characterized in that the means include at least one, preferably an unbalanced vibrator (16) trained, vibrator and preferably at least one distributor base (32) include. 8. Preparation chamber, preferably according to at least one of the claims, characterized in that the bottom of the chamber (4) has one or more cascades having, wherein a compressed air can be acted upon preferably in at least one increment Blowing element (36) is provided to pneumatically accelerate the falling concrete stream. 9. Preparation chamber, preferably according to at least one of the claims, characterized in that the blowing element is arranged in the area of the increment and is designed as an annular nozzle or part of an annular nozzle. 10. Preparation chamber, preferably according to at least one of the claims, characterized in that it has at least two compressed air connections, wherein the one, preferably in the area of the concrete feed, the processing of the concrete is used, while the second, e.g. opening into the chamber floor, is the pneumatic one Promotion serves. 11. Preparation chamber, preferably according to at least one of the claims, characterized in that in the longitudinal direction of the acceleration chamber (54) in Upper part of the nozzle a preferably adjustable insert for changing the free Passage is provided. 12. Preparation chamber, preferably according to at least one of the claims, characterized in that the concrete feed in the lower and the connection for the conditioning air in the upper half of the chamber. 13. Preparation chamber, preferably according to at least one of the claims, characterized in that this chamber (4) is divided into a processing (19) and a Acceleration chamber (54) is divided, the two preferably by means of a quick release fastener (56, 57) are connected. 14. Preparation chamber, preferably according to at least one of the claims, characterized by net that the distributor base (32), preferably adjustable with respect to the horizontal, at least partially a compressed air chamber (34) limited. 15. Preparation chamber, preferably according to at least one of the claims, characterized in that the chamber (4) is rubber-elastic, e.g. on rubber buffers (39), and preferably adjuster (42) has to change the longitudinal inclination of the chamber (4). 16. Preparation chamber, preferably according to at least one of the claims, characterized in that connection means (38) are provided around the chamber (4) flush with pressurized water. 17. Preparation chamber, preferably according to at least one of the claims, characterized in that a single cascade (36) is provided, which on about half the cross section of the acceleration nozzle (54) proven. 18. Preparation chamber, preferably according to at least one of the claims, characterized in that the processing chamber (19) and the acceleration chamber (54) are approximately the same length and preferably the largest diameter to the smallest behaves like 4: 1 at most. 19. Preparation chamber, preferably according to at least one of the claims, characterized in that it relates to the accumulation of concrete in the preparation chamber is self-regulating, such that the vibrator effect increases as it grows and vice versa.