VAN DER KLOOSTER, Johannes Gommert (Verwersstraat 20d, HW 's-hertogenbosch, NL-5211, NL)
Claims
1. Method for manufacturing a structural element manufactured from concrete, wherein the method comprises the following steps of: - providing a formwork closed on all sides; and carrying the liquid concrete mass into the formwork via a pouring channel, characterized in that the liquid concrete mass is formed by concrete mass for forming concrete with a strength greater than or equal to that of high-strength concrete, and that during the pouring the formwork is de-aerated through de-aerating openings which are arranged in the formwork and which are permeable to air but not to water and liquid concrete.
2. Method as claimed in claim 1, characterized in that air present in the formwork during the pouring is discharged via the de-aerating openings, de-aerating channels connecting to the de-aerating openings and an air pump connected to the de-aerating channels.
3. Method as claimed in claim 1 or 2, characterized in that the formwork comprises external parts and internal parts, and that the internal formwork parts are placed in the external formwork parts prior to pouring, wherein the de-aerating openings and the de- aerating channels connected thereto are arranged in the internal formwork parts.
4. Method as claimed in any of the foregoing claims, characterized in that the internal formwork parts are connected to the associated external formwork parts by means of releasable connections, such as magnetic connections.
5. Method as claimed in any of the foregoing claims, characterized in that the formwork removal takes place by removing a wall of the external formwork, and by pressing outward in the manner of a plunger from the opposite side the opposite wall of the external formwork. the part of the internal formwork connected thereto, the structural element and the part of the internal formwork on the side where the wall of the external formwork has been removed.
6. Method as claimed in claim 5, characterized in that at least one air channel with outflow openings arranged on its underside is placed in the interior of the formwork. which channel is incorporated in the workpiece during pouring, and that after the removal of a side wall of the formwork a compressed air source is connected to the air
5 chamber in order to form an air cushion during at least the formwork removal.
7. Method as claimed in any of the foregoing claims, characterized in that the formwork is adapted to form a part of a swimming pool basin and that the structural element is a part of a swimming pool basin.
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8. Method as claimed in any of the foregoing claims, characterized in that during pouring the liquid concrete is supplied under pressure relative to the formwork.
9. Method as claimed in claim 8, characterized in that the pressure is generated by 15 a peristaltic pump.
10. Method as claimed in claim 8, characterized in that the pressure is generated by a compressed air source.
_' ( ! I I . Method as claimed in claim 8, characterized in that the pressure is generated by a plunger movable in a vessel.
12. Method as claimed in any of the claims 8-11, characterized in that after mixing the concrete mixture is de-aerated by means of a vacuum pump.
13. Method as claimed in any of the foregoing claims, characterized in that the parts coming into contact with liquid concrete are impregnated prior to pouring with a release agent such as oil.
" *0 14. Formwork for forming a structural element manufactured from concrete, characterized in that the formwork is closed on all sides and that it is adapted to form a structural element of concrete with a strength greater than or equal to that of high- strength concrete, and that de-aerating openings are arranged in the formwork which are permeable to air but not to liquid concrete.
15. Formwork as claimed in claim 14, characterized in that the formwork is adapted to form a structural element with a wall thickness which is small relative to a similar structural element manufactured from concrete of normal strength.
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16. Formwork as claimed in claim 14 or 15, characterized in that the formwork comprises external parts and internal parts, and that the de-aerating openings and the de- aerating channels connected thereto are arranged in the internal formwork parts.
IU 17. Formwork as claimed in claim 14, 15 or 16, characterized in that there is arranged in the de-aerating channel a valve adapted to allow passage of air but to stop water.
18. Formwork as claimed in claim 17, characterized in that the valve is provided
: ^ wiih a chamber and a float which is placed therein and which in its uppermost position closes an upward directed discharge channel and in its lowermost position leaves the discharge channel clear.
19. Formwork as claimed in claim 16, 17 or 18, characterized in that the internal 20 formwork parts are connected to the associated external formwork parts by means of rclcasable connections, such as magnetic connections.
20. Formwork as claimed in any of the claims 16-19, characterized in that the de- acrating channels are adapted for connection to a vacuum pump. j 5
21. Formwork as claimed in any of the claims 14-20, characterized in that the formwork is adapted for the purpose of fixing during pouring lining elements to be incorporated in the structural element.
' .li 22. Formwork as claimed in claim 21. characterized in that the formwork is adapted for the purpose of fixing the lining elements against the upper wall of the formwork.
23. Formwork as claimed in any of the claims 14-22, characterized in that the external formwork is provided with at least one detachable side wall and that the side
wall of the external formwork opposite the detachable side wall is adapted to be moved into the external formwork in order to move the workpiece outward.
24. Formwork as claimed in claim 23, characterized in that the formwork is adapted 5 to move at least parts of the internal formwork outward together with the workpiece.
25. Formwork as claimed in any of the claims 16-24, characterized in that the internal formwork is manufactured from a material, such as plastic, impregnated with oil or another release agent.
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26. Structural element manufactured from concrete as part of a swimming pool basin, characterized in that the structural element is manufactured from concrete with a strength greater than or equal to that of high-strength concrete, that the wall thickness of ihe structural element is small relative to a similar structural element manufactured from l > concrete of normal strength, and that the structural element is provided with strengthening ribs on its outer side.
27. Structural element as claimed in claim 26, characterized in that the concrete is reinforced with fibres.
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28. Structural element as claimed in claim 26 or 27, characterized in that air channels are incorporated in the structural element adjacently of at least one outer surface of the structural element, that outflow openings debouching in the outer surface of the structural element are arranged in the air channel and that the air channel is
25 coupled to connecting means for connecting a compressed air source to the air channel.
29. Structural element as claimed in any of the claims 25-28, characterized in thai the structural element is provided with cast in place lining elements. |
Method, device for manufacturing a concrete structural element, and thus manufactured structural element
The invention relates to a method for manufacturing a structural element manufactured from concrete, wherein the method comprises the steps of providing a formwork closed on all sides and carrying the liquid concrete mass into the formwork via a pouring channel. Such a method is generally known.
There has been growing interest in recent times in so-called high-strength concrete, partly because of the resulting savings in material and mass. Pouring of this type of concrete does however entail problems, such as the smaller grain size and the associated greater homogeneity of the liquid concrete. Although the types of concrete falling within this concrete category flow well, they tend to form air bubbles, partly due to the usually smaller thickness of the formed structural elements. These air bubbles result in a significant reduction in strength and, when they are situated at the surface, in a deterioration in the appearance. High-strength concrete is understood to mean the following types of concrete: self-compacting concrete (B35-B75), high-strength concrete (B75-B105), very high-strength concrete (Bl 05-Bl 50), ultra high-strength concrete (B15O-B2OO) and super high-strength concrete (B200-B800). High-strength concrete is also understood to mean all the above stated types of concrete individually and in any random combination.
The present invention has for its object to prevent or reduce this problem.
This object is achieved by such a method wherein the liquid concrete mass is formed by concrete mass for forming concrete with a strength greater than or equal to that of high- strength concrete and wherein during the pouring the formwork is de-aerated through de-aerating openings which are arranged in the formwork and which are permeable to air but not permeable to water or concrete.
The formation of air bubbles is greatly reduced as a result of these measures.
The objective is also achieved by a formwork closed on all sides for forming a structural element manufactured from concrete, wherein the formwork is adapted to form a
structural element of concrete with a strength greater than or equal to that of high- strength concrete, and de-aerating openings are arranged in the formwork which are permeable to air but not to water and therefore not to liquid concrete. It is noted here that in high-strength concrete it is the aim that the amount of water in the mixture be exactly right; it is therefore less attractive when water runs out when the mixture is carried into the formwork or during curing. It is therefore recommended that the openings are adapted only for passage of air and not water.
The advantages of the present invention become particularly manifest in a formwork which is adapted to form a structural element with a wall thickness which is small relative to a similar structural element manufactured from concrete of normal strength.
According to a first preferred embodiment, the air present in the formwork during the pouring is discharged via the de-aerating openings, de-aerating channels connecting to the de-aerating openings and an air pump connected to the de-aerating channels. Air bubbles are hereby prevented from occurring in the concrete. In concrete of usual strength this is generally less of a problem, but in structural elements manufactured from high-strength concrete the wall thicknesses are generally much thinner, so that the possible air bubbles have a very adverse effect on the strength of the structural element.
These advantages likewise become manifest when the de-aerating channels are adapted for connection to a vacuum pump.
The formwork is therefore preferably adapted to form a structural element with a wall thickness which is small relative to a similar structural element manufactured from concrete of normal strength.
The formwork preferably comprises external parts and internal parts and the de-aerating openings and the de-aerating channels connected thereto are arranged in the internal form work parts.
According to a specific preferred embodiment, there is arranged in the de-aerating channel a valve adapted to allow passage of air but to stop water An effective aeration is hereby combined with preventing outflow of liquid concrete mixture.
This embodiment can be implemented in simple manner when the valve is provided with a chamber and a float which is placed therein and which in its uppermost position closes an upward directed discharge channel and in its lowermost position leaves the 5 discharge channel clear. It is not only hereby possible to achieve an effective separation between air on the one hand and water or concrete on the other using structurally simple means, but this configuration also acts as a closing means when creating vacuum in the interior of the form work. In its lowest position the float does after all close the valve connecting the channel to the interior of the formwork.
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According to a further preferred embodiment, the formwork comprises external parts and internal parts, and the internal formwork parts are placed in the external formwork parts prior to pouring, wherein the de-aerating openings and the de-aerating channels connected thereto are arranged in the internal formwork parts. The internal elements
1 5 hereby fulfil the function of determining the form of the structural element, but also that of discharge means for air enclosed in the formwork and displaced by the concrete mixture. The first function makes it possible to easily vary the form of the structural elements by only placing another internal formwork element into the external formwork.
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The internal formwork elements are therefore preferably manufactured from easily proccssable material such as plastic. They here only have to transfer forces during pouring and curing to the external formwork elements, which can be manufactured with a tireater strength and which can be retained with different forms of internal formwork.
The flexibility of the method is simplified when the internal formwork parts are connected to the external formwork parts by means of releasable connections.
This embodiment also relates to such a formwork in which the internal formwork parts " S(I are connected to the associated external formwork parts by means of releasable connections, such as magnetic connections.
A specific preferred embodiment provides a method wherein the formwork removal takes place by removing a wall of the external formwork, and by pressing outward in
lhc manner of a plunger from the opposite side the opposite wall of the external form work, the part of the internal form work connected thereto, the structural element and the part of the internal formwork on the side where the wall of the external formwork has been removed.
This embodiment likewise relates to a formwork of the above stated type, which is provided with at least one detachable side wall and wherein the side wall of the external formwork opposite the detachable side wall is adapted to be moved into the external formwork in order to move the structural element outward and through such a formwork which is adapted to move at least parts of the internal formwork outward together with the structural element.
Structural elements are provided, particularly though not exclusively, with lining elements such as tiles or pieces of natural stone. The production method for such covered elements is simplified when lining elements are placed in the formwork prior to pouring.
This embodiment moreover relates to a formwork which is adapted for the purpose of fixing during pouring lining elements to be incorporated in the structural element, and a structural element provided on its inner side with cast in place lining elements.
The formwork can be adapted for the purpose of fixing the lining elements on the upper wall of the formwork.
According to another preferred embodiment at least one air channel with outflow openings arranged on its underside is placed in the interior of the formwork, which channel is incorporated in the workpiece during pouring, and wherein after the removal of a side wall of the formwork a compressed air source is connected to the air chamber in order to form an air cushion or air bearing during at least the formwork removal. Moving of the structural element outward is hereby greatly facilitated. This simple provision incorporated in the structural element can also be further used in the handling process, for instance when placing the structural element in position at the construction site.
These advantages are likewise obtained when air channels are incorporated in the structural element adjacently of at least one outer surface of the structural element, outflow openings debouching in the outer surface of the structural element are arranged in the air channel and the air channel is coupled to connecting means for connecting a 5 compressed air source to the air channel.
The advantages of the above stated measures are particularly though not exclusively manifest when the formwork is adapted to form a part of a swimming pool basin and when the structural element is a part of a swimming pool basin. Although it is possible
10 for a U-shaped structural element to be obtained with the above described method, it is recommended, partly in respect of the further processing, that the bottom and the side walls are manufactured as separate elements. It moreover becomes easier hereby to produce the elements in the correct position so that turning over of the elements during further handling is avoided.
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The invention therefore also relates to a structural element which is formed, particularly but not exclusively, by a structural element as part of a swimming pool basin and which is provided with fibres for the purpose of performing the reinforcing function. The use of high-strength concrete does after all make the use of separate reinforcement
JO unnecessary in many cases, wherein the addition of fibres, such as strong synthetic fibres or metals, preferably fibres manufactured from stainless material, increases the tensile strength of " the manufactured structural element. Furthermore, these fibres do not disrupt the pouring process, or hardly so. The use of high-strength concrete makes it possible to manufacture a structural element of the above stated type wherein the wall
25 thickness of the structural element is small relative to a similar structural element manufactured from concrete of normal strength, and wherein the structural element is provided with strengthening ribs on its outer side.
In order to avoid still further the inclusion of air and thereby the formation of air ">u bubbles in the structural element, it is recommended that during pouring the liquid concrete is supplied under pressure relative to the interior of the formwork.
The pressure can be generated here by a compressed air source. It is however also possible for the pressure to be generated by a plunger movable in the bunker or by a
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displacement pump such as a peristaltic pump. This measure provides the option of using an easily releasable formwork which can be used with great frequency, in particular when the separate side parts are formed by separate parts which have the formwork removed simultaneously with the concrete element. When plastic is used for 5 this purpose, these parts can be easily released from the concrete element with the form work removed, and be cleaned and reused.
In order to prevent inclusion of air in the concrete mixture, it is recommended that after mixing the concrete mixture is de-aerated by means of a vacuum pump. 0
In order to facilitate release of the structural element, it is recommended that the parts coming into contact with liquid concrete are impregnated prior to pouring with a release agent such as oil.
15 Yet another preferred embodiment provides the measure that at least one air channel vs ith outflow openings arranged on its underside is placed in the interior of the formwork. this channel being incorporated in the workpiece during pouring, and that after the removal of a side wall of the formwork a compressed air source is connected to ilic air channel for the purpose of forming an air cushion at least during formwork
:0 removal. The formwork removal is greatly simplified by this measure; by feeding air to the at least one channel while pressing out the structural element an air cushion is formed between the structural element and the bottom surface of the formwork, whereby hardly any friction occurs between these parts, and the forces to be generated during pressing-out are small, thus preventing damage to the structural element.
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In accordance with the same measure, at least one air channel is incorporated in the structural element adjacently of at least one outer surface of the structural element, outflow openings debouching in the outer surface of the structural element are arranged in the air channel and the air channel is coupled to connecting means for connecting a >() compressed air source to the air channel.
The present invention will now be elucidated with reference to the accompanying drawings, in which:
Figure 1 is a perspective view of a formwork according to a first embodiment of the invention;
Figure 2 is a cross-sectional view along line H-II in figure 1;
Figure 3 is a cross-sectional view along line IH-III in figure 1 ; 5 Figure 4 is a cross-sectional view of a formwork according to a variant of the embodiment shown in the above stated figures;
Figure 5 is a cross-sectional view of a formwork according to another embodiment;
Figure 6 is a cross-sectional view of a formwork according to yet another embodiment;
Figure 7 is a detailed cross-sectional view of a formwork according to yet another 10 embodiment;
Figure 8 is a schematic perspective view of a structural element for a swimming pool;
Figure 9 is a schematic perspective view of a combination of a pouring bunker and a formwork connected to the pouring bunker;
Figure 10 is a cross-sectional view of a formwork according to an alternative ! 5 embodiment, wherein the division of the formwork into an internal formwork and an external formwork can be seen;
Figure 1 1 is a partial cross-sectional view of a structural element provided with an air channel for generating an air cushion; and
Figure 12 is a cross-sectional view of a closing means for use with the measures JO according to the invention.
Figure 1 shows a formwork designated as a whole with 1, comprising a lower panel not shown in the drawing, four side panels 3a, 3b, 3c and 3d and an upper panel 4. Arranged in upper panel 4 is a pouring opening 5 for the purpose of pouring the concrete into the .15 interior of the formwork. The formwork is dimensioned for the purpose of forming a rectangular structural element. It will be apparent that at least one of the panels is placed so as to be releasable from the other panels in order to enable removal of the formwork.
For the purpose of de-aerating the interior of formwork 1 use is made of de-aerating ><! opening 6 which is arranged in upper panel 4 and which connects to a de-aerating conduit 7 in which a closing means 8 is arranged. For the purpose of guiding the air hubbies created during the pouring toward de-aerating opening 6 grooves 9 are arranged on ihe underside of the upper panel. This is otherwise also apparent from the cross- sections of figures 2 and 3. Although it is possible to leave the grooves open, provided
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the dimensions thereof are sufficiently small to prevent concrete collecting in the grooves, it is recommended that the grooves are at least partially filled with material 10 which is non-permeable to concrete but which does allow passage of air.
5 In the above embodiment the material which is permeable to air but non-permeable to concrete is arranged only in the grooves. It is also possible to arrange pieces of such material on larger surface areas, wherein a connection to one or more de-aerating openings must be guaranteed. Such a situation is shown in figure 4. As in the embodiment shown in figures 1, 2 and 3, the pouring opening is here arranged in upper i (» panel 4 of formwork 1. De-aerating openings 6a and 6b are however arranged in mutually opposite side panels 3b, 3d. Arranged against the inner surface of the side panels are pieces l la, 1 1 b of the material which is permeable to air but non-permeable to water and concrete and which pieces of course connect to de-aerating openings 6a and 6b.
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Figure 5 shows a cross-section of a formwork 1 similar to figure 3, wherein the structural element for manufacturing in the formwork is provided with lining elements in the form of tiles 12. These tiles are herein placed in the formwork and are as it were "cast in place" during the pouring, this greatly simplifying production. Fixation elements
'< ; in the form of vacuum clamps 15 are arranged for this purpose in upper panel 4 of formwork 1. Tiles 12 are here arranged with a mutual interspacing in the form of a groove 16. not only in the direction shown in the drawing but possibly also in the direction extending transversely thereof. The width of groove 16 is chosen here such that the concrete does not extend into groove 16, for instance because the width is
25 smaller than the grain size of the concrete mass. It is possible here that the concrete mass extends into a part of groove 16 and the air is discharged via the part remaining clear, for instance to a de-aerating opening 6 in the upper panel, for which purpose a tile is for instance missing from the pattern, or via a de-aerating opening arranged in one of the side walls.
Figure 6 shows a similar configuration wherein grooves 17 are arranged for the same purpose in tiles 12 themselves.
Figure 7 shows a detail of a formwork 1, comprising a removable upper panel 3, a lower panel 2 and side panels, of which one, 20a, is shown. Arranged in side panel 20 is an opening 21 through which extends a toadstool-shaped element 22. The toadstool-shaped element is provided with a ring 23 which is placed in a cavity 24, wherein a spring 25 5 urges ring 23 and thereby toadstool-shaped element 22 outward. The head 26 of the toadstool-shaped element extends in a groove 28 extending in a removable element 27 preferably manufactured from plastic. This groove 28 allows a vertical movement of removable element 27 together with the formed structural element when the formwork is released. For form locking with the formed concrete structural element the removable IO element 27 is provided with protrusions 30.
Figure 8 further shows a structural element 32, manufactured according to the present inv enlion. in the form of a component for a swimming pool. It will be apparent that various changes must be made to the form of the above elucidated formworks.
Figure 9 shows a formwork 31 for a swimming pool element 32 to be poured. The swimming pool element comprises a floor 33 and two wall parts 34 and 35. The formwork is formed accordingly. Formed on a formwork part of wall part 34 is a pouring point to which a concrete supply conduit 36 is connected in airtight manner.
J) This concrete supply conduit 36 is likewise connected airtightly to a concrete bunker 37. The concrete bunker is provided with means for applying a pressure, in the situation shown in figure 9 by means of a plunger 38 movable inside the concrete bunker and driven by a linear displacement member. Alternatively, concrete bunker 37 can be pro\ ided with a connection for compressed air. These means for supplying liquid
.':> concrete under pressure to formwork 31 achieve that the liquid concrete reaches all parts of the formwork before the concrete cures or the concrete does not reach the extremities of the formwork as a result of the flow resistance.
Figure 10 shows a formwork 40 which is formed by external formwork parts 41.42, 43 M'I and 44, which are usually manufactured from steel, and internal formwork parts 45. 46. 47 and 48. which are preferably manufactured from plastic. The internal formwork parts enclose a cavity 49 in which the structural element must be cast. The internal formwork parts are each connected to the relevant external formwork parts by means of magnets
50. λ sealing profile 521 is placed between each pair of internal formwork parts 45-48 in order to prevent the concrete mixture flowing out of cavity 49.
Arranged in internal formwork parts 45-48 are air channels 52 which can be connected 5 by means of connecting lines (not shown in the cross-section) to a vacuum pump
(likewise not shown in the drawing). Connected to each of the air channels is a number of outflow openings 53. The dimensions of the outflow openings are so small that the concrete mixture cannot enter the air channels but that air can reach the air channels and can then be discharged by the vacuum pump. Cavity 49 is connected by means of a i 0 supply conduit (not shown in the drawing) to the supply device for liquid concrete, which is preferably adapted to supply concrete under pressure.
Figure 1 1 shows a cross-sectional view of a structural element 60 manufactured according to the present invention, wherein an air channel 62 is cast in place connecting
15 to bottom surface 61. The air channel is provided with a number of openings 63 through w hich air can exit to the outside. The air channel is provided for this purpose with a connection tor a compressed air source with which the compressed air can be supplied to the air channel. The air exiting as a result hereof serves to generate an air cushion with which movement of the structural element can be facilitated. This is not only the
20 case for removing the structural element from the formwork, but also for further transport of the structural element, including placing thereof in its position at the construction site. It will be apparent that this configuration can also be changed in various ways; a plurality of air channels 62 can thus be incorporated in the structural element, particularly on the edges of the lower surface of the structural element.
_!5 Conversely, it is also possible to generate an air cushion by arranging the air channel or the air channels in a part of the formwork; these air channels can here be used only during removal of the structural elements from the formwork; when further use must also be made of air cushions for transporting the structural elements, use must be made of supporting parts provided with such air channels.
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Use can also be made of a system for enclosing the air cushion formed beneath a structural element, for instance by making use of inflatable skirts or bellows around the edge of the lower surface of the air cushion.
Figure 12 shows a cross-sectional view of an internal formwork part 47 through which an air channel extends. In the present embodiment this air channel takes the form of a chamber 65 in which a float 66 is placed. Chamber 65 is connected to outflow openings 53 by means of short discharge channels 67, and the chamber is connected to a 5 discharge channel 68 leading to a vacuum pump. When no liquid is present in chamber 65. float 66 will rest on the outflow openings of channels 67 in chamber 65. When a vacuum is generated, float 66 will move upward, whereby these openings are left clear and air flowing out of the interior of the formwork enters discharge channel 68. When water or a liquid concrete mixture flows through one of the discharge channels into I ϋ chamber 65, the float will begin to float because the density of the float is lower than that of water, whereby channel 68 is closed. This prevents concrete or water leaving the interior of the formwork.
It will be apparent that the shown configuration can be varied in numerous ways; the .5 show n example relates to a round configuration, although it can also be embodied in rectangular or other form. It is likewise possible for the valve to be positioned at a different location.
It will be apparent that the diverse embodiments shown can be combined.
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