| 1. | Arrangement to form a leadthrough in a construction of concrete, comprising a hollow spacer (3) and at least one hollow endpiece (1, 4, 5), wherein the endpiece (1, 4,5) is removed after curing of the concrete, c h a r a c t e r i z e d i n that a removeable separate bushing (2) with external threadlike denticulations (10), wherein the bushing is designed for arrangement to the exterior of the endpiece before pouring, to form grooves in the concrete. |
| 2. | Arrangement according to claim 1, c h a r a c t e r i z e d i n that the endpiece (1,4, 5) is adapted to the bushing (2). |
| 3. | Arrangement according to claim 1, c h a r a c t e r i z e d i n that the denticulations (10) comprise raised parts which extend from one end of the bushing (2) to form a threadlike configuration in the cured concrete. |
| 4. | Arrangement according to claim 3, c h a r a c t e r i z e d i n that each raised part which constitute the denticulations (10) of the bushing (2) extends around a part of the periphery of the bushing (2). |
| 5. | Arrangement according to claim 1, c h a r a c t e r i z e d i n that the bushing (2) is made of a flexible material. |
| 6. | Arrangement according to claim 4, c h a r a c t e r i z e d i n that the bushing (2) has a compressive strength sufficient to withstand the pressure of the concrete during pouring. |
| 7. | Arrangement according to claims 16, c h a r a c t e r i z e d i n that aplug (6) or a cover (7) is adapted to the denticulations (10) of the bushing (2), and is designed for introduction into the concrete after removal of the endpiece (1) and the bushing (2) and to seal the cavity in the spacer (3). |
| 8. | Arrangement according to claim 7, c h a r a c t e r i z e d i n that the cover (7) has weakened regions to facilitate creating openings in the cover (7). |
| 9. | Arrangement according to claim 7, c h a r a c t e r i z e d i n that the plug (6) has openings (9) for injection of a sealing compound. |
| 10. | Method for sealing of a leadthrough in a construction of concrete, wherein a cavity is sealed by means of plugs or covers (7), c h a r a c t e r i z e d i n that the plugs (6) or the covers (7) are arranged in threadlike grooves formed in the concrete by a removable bushing (2) installed prior to pouring. |
| 11. | Method according to claim 10, c h a r a c t e r i z e d i n that the plugs (6) or the covers (7) are arranged in the grooves, and the cavity subsequently is filled with a sealing compound. |
| 12. | Method according to claim 10, c h a r a c t e r i z e d i n that the plugs (6) or covers (7) are arranged in the grooves, objects such as piping or ducts are introduced in the leadthroughs, and the cavity is filled with a sealing compound. |
Background art Lead-throughs in concrete walls and decks are found in all kinds of constructions. Examples of such lead-throughs are openings for stays when shuttering walls or decks for technical installations in the final construction.
Currently the existence of complete solutions to provide such lead-throughs is lacking, both in quality, execution and design.
Several methods for providing lead-throughs for stays when shuttering and pouring walls, are currently in use. One method. discloses a bushing with hollow frustoconical end pieces through which the stays are introduced to support the formwork of e. g. a wall. After curing of the concrete the end pieces are removed and the ducts are filled with concrete. It has been proven difficult to seal the duct with concrete due to lack of adherence between the cured concrete and the mortar used. Further it is difficult to remove the frustoconical end pieces without damaging the surrounding concrete. Removing the end pieces is also time- consuming and not cost effective.
In other known arrangements, e. g. in US 4,196, 906, where the end pieces are sealed by means of a plug, the material will deterioriate over time and leakages will occur.
Further all use of plastic plugs will provide poor
adherence for possible refacing, which may result in scaling or chipping.
When running piping or cables through walls and decks, recesses or cut outs are provided in the construction. The supplementary work in such an operation is substantial. The formwork should envelope the pipe and the installation of this formwork often results in damages on the surrounding regions. Further, it is difficult to obtain a sealing with the required quality, especially in areas with fire barriers.
Recently, post-tensioning of concrete constructions has been common, especially in bridges and deck constructions.
In known art, the conical end-pieces at the fixings of the tensioning cables are removed and the aperture is filled with mortar. As for the above described stay-solution, lack of adherence and waste will eventually result in leakages and loss of quality. This is alarming considering that the poststressing steel armatures are sensitive to corrosion.
Different solutions to form duct and openings through concrete are described, for example DE2522887 describes a solution where threaded conical end-pieces with a spacer tube similar to the present invention. However, this device has the disadvantage that it is hard to remove the end- pieces after the concrete is cured. The grooves are formed as threads in the concrete, and it is difficult to remove the end-pieces without damaging the threads. The purpose of the threads is according to the invention to simplify removal of the cone after curing of the concrete. It is not an object of this prior invention to make use of these grooves formed in the concrete. It is also a problem that the surrounding concrete is damaged when removing such conical end-pieces.
A further disadvantage with known solutions is that the spacer-tube and the end-pieces are subjected to excessive
strain during shuttering and expand when the formwork is removed. Hence stress arises in the construction and cracks may be formed and propagate, which makes it difficult to obtain a sealed construction.
Brief description of the invention The main object of the present invention is to solve the problems of the prior art. Improved quality and an easier application will be less time consuming and incur lower costs.
It is an object of the present invention to form lead- throughs and openings in constructions of concrete which can be sealed in an effective and secure way while providing an aesthetic finish.
It is a further object of the invention to provide a device which forms grooves in the cured concrete for arranging plugs or covers for sealing the lead-through or opening.
Yet another object of the present invention is that the grooves in the cured concrete are formed by a bushing which can easily be removed without damaging the surrounding concrete.
Another object of the present invention is that the plugs or covers act as formwork when injecting or introducing expanding concrete during sealing in order to avoid the problems associated with shuttering and post sealing of the ducts and openings.
A further object of the invention is to provide an arrangement which can accept a certain amount of compression during shuttering without damaging the concrete due to expansion.
It is also an object of the present invention to provide a solution for forming an opening in concrete which can be applied when forming openings for stays when shuttering as well as for forming openings and ducts for leadthrough of piping electrical wiring etc. and for sealing off post- tensioning cables in constructions of concrete.
The above objectives are achieved by an arrangement and a method according to the appended claims.
Brief description of the drawings Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, where: Figure la is a perspective view of an embodiment of an arrangement according to the present invention, Figure 1b is a side view of the arrangement in figure 1 a, Figure 2 is a perspective view of an embodiment of a conical end piece according to the invention, Figure 3 is a perspective view of a second embodiment of an end piece, in the form of an installation ring, Figure 4 is a perspective view of a third embodiment of an end piece, Figure 5 shows an embodiment of a bushing according to the invention, Figure 6a and 6b shows an embodiment of a plug according to the invention, Figure 7 and 8 shows examples of embodiments of the plug in figure 6a and 6b, and
Figure 9a-9c shows three different embodiments of a cover according to the invention.
Detailed description of the invention The invention comprises a spacer tube 3, a conical end piece 1, bushing 2 and a plug 6. The spacer-tube 3 may be produced of plastic material or fibre reinforced concrete.
The end piece 1 matches the bushing 2 and is slightly conical. The bushing 2 is made of a flexible material with a compressive strength as low as possible but sufficient to withstand the pressure of the concrete during pouring. The bushing is further provided with denticulations comprising a plurality of teeth forming a thread like configuration in the cured concrete. Each tooth does not run completely around the periphery of the bushing 2 which is the case for most conventional threads. This will ease the removal of the bushing 2 : and facilitate the positioning of the plug 6.
The bushing 2 is preferably cylindrical and is removed by distorting and/or twisting the bushing, which is made possible due to the flexibility of the bushing 2. The bushing can be made disposable or reuseable. The bushing can be made of any suitable material, preferably a flexible plastic material.
Figur 1 shows an embodiment for providing lead-throughs for stays when shuttering walls or decks. In this field of application the present invention will provide a durable seal of the construction as well as simple installation and use. The bushing 2 is placed on the conical end-piece 1 and is installed with the spacer-tube 3 which preferably is made of fibre reinforced concrete. The stay is brought through the formwork and is fastened in a conventional way to support the formwork during pouring of the construction.
After curing of the concrete and removal of the formwork, the conical end piece 1 and the bushing 2 can be removed.
According to the invention, the bushing 2 is made of a flexible material and can be removed using an appropriate
tool or manually by hand. The flexibility of the bushing 2 makes it possible to remove the bushing 2 without damaging the surrounding concrete. Hence, a denticulation is formed which facilitates fastening of a plug 6. Note that the denticulation does not run completely around the periphery of the bushing and facilitates the positioning of the plugs 6 or covers 7, 8,9 at different orientations. This feature will be described below with respect to use of the invention for making lead-throughs for ducts and pipes.
The plug 6 can be made of fibre reinforced concrete and is produced with sufficient clearance according to the denticulations which will be formed in the concrete.
Expanding mortar is applied to the plug 6 and the plug is pushed and twisted into position. If desired the plug 6 can be provided with openings to facilitate injection of an adequate material in the cavity in the construction. On the inner end, the plug 6 may be provided with a compressible portion (not shown), e. g. foam plastic, or a groove in the plug 6 covered by a flexible membrane to absorb expansion of the mortar injected into the cavity.
This system also makes it possible to utilize the plugs for decoration of a construction. Examples of possible designs are shown in figure 7 and 8.
Application of the present invention when forming ducts and openings for lead-through of piping electrical wiring etc, provides a simple but high quality and aesthetic solution.
The system comprises a spacer-tube, and an installation ring 4 shown in figure 3, a bushing and a cover 7,8, 9 shown in figures 9a-9c. The bushing is formed similar to the embodiment described above, but the dimensions are adjusted to the size of the duct or opening which is going to be formed. In this embodiment, the spacer-tube is made of a plastic material, wood fibre material (cardboard) or a fibre reinforced concrete. All of the appropriate materials have a coarse surface in order to provide sufficient
adherence to the surrounding material. The installation ring 4 is made of a plastic material and will form the base for fastening the cover and the spacer tube. After curing of the concrete and removal of the formwork, the installation ring 4 and the bushing 2 are removed. A denticulation has been formed in the concrete to receive the cover 7. The cover 7 can be made of various materials depending on the application e. g. plastic material, thin steel sheet material, or fibre reinforced concrete. The cover 7 is provided with openings for various tubing, ducts, wiring etc. The opening in the cover can be of any geometry. It is therefore possible to lead rectangular duct through the circular covers as shown in figure 9. The number of openings and the dimensions of a cover can also vary, for example one opening of 0200 mm and two openings of 0100.
An elastic membrane or gasket may be provided around the edge of the openings in the covers to seal the gap between the piping, duct, wire etc. and the cover.
I some cases the object passing through the concrete construction is angled, hence it does not pass the construction at a 90° angle. The present invention solves this situation by rotating the covers. The opening in the cover 7 is positioned off centre of the cover as shown in figure 9, hence the two corresponding covers on opposite sides of the construction can be rotated relative to each other to obtain the desired angle. The configuration of the denticulations makes this possible. The denticulations do not extend around the periphery of the cover and the mutual distance between the denticulations determine the rotation of the cover for each step of rotation.
According to the other applications, the cover 7 is fastened by applying expanding mortar and subsequent positioning of the cover by pushing and twisting. After positioning the cover, the cavity between the-spacing tube
and the object which is lead through the opening can be filled by injection. The substance used should meet the requirements in each specific case. For lead-throughs in structures with fire classification, the substance must of course be fire-retardent. The cover 7 is therefore provided with two openings, one for injection and one for ventilation, placed at the edge symmetrically around the centre of the cover 7. The cover may be provided with weakened areas which can easily be removed by applying a suitable tool at the construction site. This makes it possible to ensure that the ventilation opening is placed at the highest point regardless of the position of the cover 7 to secure a proper sealing.
An alternative method may be applied for ventilation ducts.
Instead of introducing the duct through the wall for subsequent injection, a method without injection can be applied. In this method the cover 7 is provided with a transition region to the ventilation duct. After the first cover is fasrened, the ventilation duct accommodated on the transition region of the cover. Hence the ventilation duct does not need to be lead through the construction after curing of the concrete.
A third area of application of the present invention relates to sealing off tensioning cables in constructions of concrete. The system comprises a conical end piece 5, a bushing 2 and a plug 6. This application mainly corresponds to the application for forming lead-throughs for stays when shuttering walls or decks, but unlike this application the cavity behind the plug must be injected to provide the required sealing. Therefore, the plug 6 is provided with two openings 9, one for injection and one for ventilation, by the edge, symmetrically round the centre of the plug 6.
This makes it possible to ensure that the ventilation opening is placed at the highest point regardless of the position of the plug 6 to secure a proper sealing and improved distribution of the injected substance.
The present invention may be used on all kinds of anchoring and fixing/sealing in constructions of concrete, i. e. both prefabricated and on site installations. The bushing 2 which forms the denticulations and thread like configuration will be the basic element for all these applications. A further example for use is for vents. It is usual to provide an opening in the structure at the position of the vent and install the vent device by sealing with mortar or other suited material. According to the invention a system and method corresponding to the above embodiment related to lead-throughs of ducts may be applied, where the cover 7 may be replaced by a complete ventilation device. The application will be simple and cost effective as expanding mortar or other adhesive is applied to the denticulations of the cover to arrange a complete ventilation unit in one operation.
Next Patent: DIRECTION AND MOTION REGULATOR