EP0864692B1 - Method and apparatus for concreting of rail support points for a ballastless railway track structure - Google Patents

Abstract

Shuttering with filter liner (5) has a hollow chamber (4) corresponding to the support, and concrete is poured-in via a socket (9). The concrete has a water/cement ratio of between 0.4 and 0.6, and immediately after pouring is subjected to excess pressure in the area of the socket, and in the area of the filter liner, to underpressure, until green bond has been achieved and the shuttering can be removed. The concrete contains steel and/or plastic fibres. The excess pressure is at 1-8 kPa, and the underpressure is at 0.3-0.9 kPa. Pressure is applied over a period of 1 - 8 minutes. The shuttering is removed when the water/cement ratio is 0.30 - 0.35.

Description

The invention relates on the one hand to a method for Concreting rail bases for a ballastless Track superstructure - also known as slab track -, whereby on a slab with a filter liner, a cavity corresponding to the rail base showing slip formwork tightly and position-oriented is supported, then via a filler neck the slip form concrete into the slip form with escape of air and water introduced through the filter liner and after reaching a green stability Slip-on formwork is removed, and on the other hand a device to carry out this procedure, consisting of one lined with a filter liner, one the Corresponding cavity having the rail base Slip-on formwork, being between the filter liner and the Inverted formwork a network of interconnected depressions is provided for the removal of air and water and the cavity can be filled with concrete via a filler neck is.

As part of the known method of the type mentioned (DE 195 22 478 A1) are after filling in the concrete the slip formwork additional measures until reaching the green stability or removal of the slip formwork not realized. Nevertheless, they have known measures proven in practice, it arise precise and low-tolerance rail support points. Disadvantageous is, however, that the period of time between introductions of the concrete in the slip formwork and stripping or Reaching the basic stability passes relatively is long. In this respect there is also the mechanical effort for a continuous production of the track superstructure.

The invention is based on the technical problem in Within the known measures of the type mentioned the time span to shorten to formwork, but without the To make processing of the concrete difficult by special additives.

The achievement of this task consists in procedurally in that the one Water / cement value between 0.4 and 0.6 filled concrete immediately after filling in the filler neck over concrete pressure Overpressure and a negative pressure in the area of the filter liner exposed until the green stability is reached.

The invention is based on the surprising Realization from the fact that the green stability permitting the stripping reach much faster than before can by turning on the concrete with excess water, so that it completely fills the cavity of the slip formwork fills, and then the excess water by exposure of the concrete in the filler neck with an overpressure above the concrete pressure and in the area of the filter liner with a negative pressure above expels the filter liner and accelerates the associated volume reduction of the in the cavity concrete by automatic tracking of Leveling out concrete from the filler neck. It is advantageous in any case, that on any concrete admixtures, the one Accelerate hardening, or on special cements, that are set for quick hardening, as well as heating the concrete to accelerate the Hardening can be dispensed with. All of that makes it easier Maintenance of the machinery used, as early Material caking and the like do not occur.

For further development there are within the Invention several ways. Generally one will work with a concrete of minimum quality B 35 according to DIN 1045. The liquid consistency required for processing of the starting concrete, which is even softer than that of a flow concrete should be in accordance with DIN 1045, by adding sufficient water, but also through a smaller amount of water and the simultaneous addition of a plasticizer or a superplasticizer. The only important thing is that the water / cement value of the starting concrete is between 0.4 and 0.6 is. Preferably a concrete with a Largest grain of 8 mm and a water / cement value of 0.55 used. It is also important how much water in the course of the Pressure treatment is removed by the filter liner. Preferably the slip formwork is removed when the concrete of the rail base a water / cement value of 0.30 up to 0.35, in particular 0.34. Otherwise it can recommend to improve durability and resistance to dynamic loads with a concrete work that contains steel and / or plastic fibers; preferably become steel fibers of 25 mm length and 0.5 mm Diameter used.

The liquid concrete is poured into the slip formwork through the filler neck located in the concrete reservoir. Either a pump is used for this, which generates a pressure of at most 1 kPa. It is also possible to let the liquid concrete run in through a funnel in free fall and then pressurize it with compressed air of 1 kPa, for example, over the concrete in the filler neck to ensure that the filter liner clings to the slip formwork everywhere. During or after this, the concrete required to compensate for the loss of volume is poured into the filler neck. The concrete located in the filler neck is then subjected to an air pressure of preferably 1 to 8 kPa, in particular 2.5 kPa. At the same time, the negative pressure is applied in the area of the filter liner. According to a preferred embodiment, this vacuum is 0.3 to 0.9 kPa, in particular 0.8 to 0.9 kPa. Overpressure and underpressure should be maintained for about 1 to 8 minutes until a compressive strength of 1 N / mm ^{2 is} reached, so that it can be switched off. The concrete body is then able to support its own weight without any disturbing deformation. To further accelerate the process or improve green stability, the concrete in the slip formwork can be shaken before stripping. The vibrations cause a reduction in the internal friction of the concrete, which facilitates the removal of air and water and the concrete is even better compacted. Since the vibrating vibrations introduced into the concrete by the slip formwork in particular compress the edge zones of the concrete body, this measure is only applied towards the end of the pressure treatment in order not to hinder the water drainage from the interior of the concrete body.

The hardening of the concrete takes several weeks Process. While this is referred to as hydration The process binds water. So here for sufficient Water must be prevented that water evaporates from the concrete during this time. Consequently, according to the preferred embodiment after the Post-treatment carried out. This can e.g. from spraying on one that prevents water release After-treatment film exist. Other treatments, such as covering with foils are also conceivable.

In terms of the device, the invention consists in
that the outer end of the filler neck can be closed by a cover which is provided with a connection for a positive pressure source, and the network has a vacuum connection for a negative pressure source. The filter liner is preferably made of cardboard, which can be fixed in the slip formwork. The cardboard is preferably made in such a way that it is not permeable even to solid-sized solids of the liquid concrete. Instead of cardboard, filter materials made from other materials can be used, e.g. woven and knitted fabrics made from artificial and natural fibers. The network of depressions used for the removal of air and water can consist of an interposed plastic or wire mesh or knitted fabric, in particular with a clear mesh size of 0.5 to 6 mm, preferably 2 mm. In another preferred variant, the network is formed from depressions provided on the inside of the slip formwork, in particular in the form of grooves with a width of 0.5 to 6 mm, preferably 2 mm and a depth of 2 to 10 mm, preferably 5 mm. The depressions in the slip formwork and the consistency of the cardboard are expediently coordinated with one another in such a way that a smooth surface of the concrete body is produced.

As stated above, the filler neck should be like this be trained to have an adequate concrete reservoir for conveying concrete during the pressure treatment. For shaking the concrete the slip formwork is preferably with a vibrator Mistake. Otherwise, the slip formwork has on her bottom edge expediently a sealing and height compensation frame on.

In the following the invention with reference to a drawing explained that schematically in a longitudinal section Device for performing the method represents.

The device is used for concreting rail support points for a ballastless track superstructure (festivals Roadway) and consists of its basic structure a slip form 1 made of cast graphite. The slip formwork 1 is with the help of appropriate facilities in the Drawing is schematically represented by arrows 2, can be pressed against the carriageway slab 3. The slip formwork 1 is positively lined with a filter liner 5, the preferably made of cardboard and in the inserted state after concreting has a contour that the desired Surface contour of the rail base corresponds. This filter liner 5 is in the slip form 1 with the help one provided at the lower edge of the slip formwork 1 Sealing and height compensation frame 6, road dowels 7 for the later rail fastening and a screw and Clamping ring 8 fixed to a filler neck 9, through which the Cavity 4 can be filled with concrete and a concrete reservoir 10, via which the resulting during the pressure treatment Volume reduction of that located in the cavity 4 Concrete can be balanced; High and low of the concrete in the filler neck 9 are indicated. In the Figure is indicated by a dashed line that between the filter liner 5 and the slip formwork 1 Network 11 interconnected wells in the form an interposed fabric or on the inside of the Slip-on formwork 1 provided grooves for discharging air and water is provided.

The filler neck 9 is with a pressure source 12, the Network 11, however, can be connected to a vacuum source 13. In detail, this is the outer end of the filler neck 9 sealed by a lid 14, the with a connection 15 for the pressure source 12, e.g. Air pressure source is provided. For the vacuum source 13 is a vacuum connection stub opening into the network 11 16 provided. There is another vibrator on the slip formwork 1 17 attached.

The device described is exemplified as follows used: First the slip formwork 1 is placed on the carriageway slab 3 set, adjusted and fixed. After that liquid concrete into the slip formwork 1 up to the one before maximum height determined by experiment, whereby the filter liner 5 is soaked and spread over the network 15 hugs the slip formwork 1. The filled in Concrete volume is at least larger by the volume that the Corresponds to the amount of water sucked out of the liquid concrete to achieve a green concrete. Then the concrete in the filler neck 9 with compressed air of 2.5 kPa, while at the cavity 4 of Slip-on formwork 1 has a negative pressure of 0.8 to 0.9 kPa becomes. The overpressure and underpressure turn water out sucked off the liquid concrete by passing it through the filter liner and the space between the network and the vacuum connection drains away. The volume that the water and Any air that may be present was previously taken in the concrete is due to the pressure drop through the filler neck 9 crushed concrete balanced. The whole takes about 2 minutes. During the last 30 seconds additionally shaken with the help of the vibrator 17. Finally, the slip formwork 1 is lifted off and the Post-treated concrete as already described.

Claims (19)

1. A method of concreting rail support points for a ballastless track superstructure, wherein covered shuttering (1) which comprises a cavity (4) corresponding to the rail support point and which is lined with a filter liner (5) is placed, sealed and positionally-oriented, on a trackway slab (3), thereafter concrete is introduced into the covered shuttering (1) via a filling nozzle (9) of the covered shuttering (1) with the escape of air and water through the filter liner (5), and the covered shuttering (1) is removed after green stability under load is reached, characterised in that the concrete, which is introduced at a water/cement ratio between 0.4 and 0.6, is subjected directly after its introduction, to an overpressure in the filling nozzle (9) which is higher than the concreting pressure, and is subjected to a reduced pressure in the region of the filter liner (5) until green stability under load is achieved.
2. A method according to claim 1, characterised in that concrete containing steel and/or plastics fibres is employed.
3. A method according to claims 1 or 2, characterised in that the concrete in the filling nozzle (9) is subjected to an overpressure of I to 8 kPa.
4. A method according to any one of claims 1 to 3, characterised in that the concrete in the region of the filter liner (5) is subjected to a reduced pressure of 0.3 to 0.9 kPa.
5. A method according to claim 4, characterised in that the concrete in the region of the filter liner (5) is subjected to a reduced pressure of 0.8 to 0.9 kPa.
6. A method according to any one of claims 1 to 5, characterised in that the concrete situated in the covered shuttering (1) is vibrated before the shuttering is removed.
7. A method according to any one of claims 1 to 6, characterised in that the concrete is subjected to the overpressure and to the reduced pressure for a period of 1 to 8 minutes.
8. A method according to any one of claims 1 to 7, characterised in that the covered shuttering (1) is removed when the concrete of the rail support point has reached a compressive strength of about 1 N/mm².
9. A method according to any one of claims 1 to 8, characterised in that the covered shuttering (1) is removed when the concrete of the rail support point has a water/cement ratio of 0.30 to 0.35.
10. A method according to any one of claims 1 to 9, characterised in that after removing the shuttering the concrete surface of the rail support point is protected from the evaporation of water.
11. An apparatus for carrying out the method according to any one of claims 1 to 10, consisting of covered shuttering (1) comprising a cavity (4) corresponding to the rail support point and lined with a filter liner (5), wherein a network (11) of interconnected indentations is provided behind the filter liner (5) for carrying away air and water, and the cavity (4) can be filled with concrete via a filling nozzle (9), characterised in that the outer end of the filling nozzle (9) can be closed by a cover (14) which is provided with a connection (15) for a source of overpressure (12), and the network (11) comprises a vacuum connection nozzle (16) for a source of reduced pressure (13).
12. An apparatus according to claim 11, characterised in that the filter liner (5) consists of a cardboard insert which can be fixed in the covered shuttering (1) and which is preferably impermeable to solids from the concrete which are the size of grains of flour.
13. An apparatus according to claims 11 or 12, characterised in that the network (11) is formed from an inserted woven fabric or knitted fabric made of plastics or wire.
14. An apparatus according to claim 13, characterised in that the woven or knitted fabric made of plastics or wire has a clear mesh aperture of 0.5 to 6 mm.
15. An apparatus according to claims 11 or 12, characterised in that the network (11) is formed from indentations provided on the inside of the covered shuttering (1).
16. An apparatus according to claim 15, characterised in that the indentations consist of channels with a width of 0.5 to 6 mm and a depth of 2 to 10 mm.
17. An apparatus according to any one of claims 11 to 16, characterised in that the filling nozzle (9) comprises a concrete reservoir (10) which is sufficient to compensate for the reduction in volume of the concrete situated in the cavity (4) on the application of the overpressure and reduced pressure.
18. An apparatus according to any one of claims 11 to 17, characterised in that the covered shuttering (1) is provided with a vibrator (17).
19. An apparatus according to any one of claims 11 to 18, characterised in that the covered shuttering (1) comprises a sealing and height compensating frame (6) at its bottom edge.

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