Device and method for casting concrete objects

Abstract

The invention relates to a device and a method wherein a product mold is placed in a basin. The product mold is filled with wet concrete and an intermediate space between the product mold and the basin is filled with a non-hardening slurry having a density substantially similar to the density of the wet concrete. During the filling, the level difference between the wet concrete surface level and the non-hardening slurry surface level is controlled such that the pressure of the wet concrete on the inside of an outer wall of the form mold is substantially balanced by the pressure of the slurry on the outside of the outer wall of the form mold. The invention thus enables the use of a product mold that differs from traditional form works in that its outer wall does not need to support the pressure of the wet concrete contained within the product cavity.

Claims

1. A device for casting a concrete product, the device comprising: a product mould, the product mould defining a product shape defining cavity, said cavity being delimited by an outer wall of the mould and being adapted to be filled with wet concrete that hardens in the cavity to form the concrete product, a slurry basin, which slurry basin is adapted to receive therein at least partially the product mould such that an intermediate space is present between at least a portion of the outer wall of the product mould and the slurry basin, a wet concrete supply device, which wet concrete supply device is adapted to provide a flow of wet concrete into the product cavity of the product mould to fill the product cavity with wet concrete, a non-hardening slurry supply device, which non-hardening slurry supply device comprises a slurry storage for storing a non-hardening slurry having a density substantially similar to the density of concrete, and which non-hardening slurry supply device is adapted to provide a flow of the non-hardening slurry into the intermediate space present between at least a portion of the outer wall of the product mould and the slurry basin, to fill the intermediate space with non-hardening slurry, and a control system, the control system comprising a control device adapted to control filling of the product cavity and/or filling of the slurry basin such that, while filling the product cavity with wet concrete and the intermediate space with non-hardening slurry, the level difference between the wet concrete surface level inside the product mould and the slurry surface level in the intermediate space of the slurry basin can be controlled.

2. A device for casting a concrete product, the device comprising: a product mould, the product mould defining a product shape defining cavity, said cavity being delimited by an outer wall of the mould and being adapted to be filled with wet concrete that hardens in the cavity to form the concrete product, a slurry basin, which slurry basin is adapted to receive therein at least partially the product mould such that an intermediate space is present between at least a portion of the outer wall of the product mould and the slurry basin, a lowering device configured for, when the slurry basin is at least partially filled with slurry, lowering the product mould into the slurry basin, more in particular for lowering the product mould into non hardening slurry held by the slurry basin, such that an intermediate space filled with non hardening slurry is present between at least a portion of the outer wall of the product mould and the slurry basin, a wet concrete supply device, which wet concrete supply device is adapted to provide a flow of wet concrete into the product cavity of the product mould to fill the product cavity with wet concrete, which wet concrete supply device is adapted to provide the flow of wet concrete into the product cavity of the product mould while the product mould is lowered into the slurry held in the slurry basin, and a control system, wherein the control system comprises a control device adapted to control the lowering device and/or the wet concrete supply device, and is adapted to control the lowering of the product mould and/or the supply of the wet concrete such that, while the product cavity is being filled with wet concrete, the level difference between the wet concrete surface level inside the product mould and the slurry surface level in the intermediate space of the slurry basin can be controlled.

3. The device according to claim 2, wherein the device further comprises a non-hardening slurry supply device, which non-hardening slurry supply device comprises a slurry storage for storing a non-hardening slurry having a density substantially similar to the density of concrete, and which non-hardening slurry supply device is adapted to provide a flow of the non-hardening slurry into the slurry basin, into the intermediate space present between at least a portion of the outer wall of the product mould and the slurry basin while the product mould is lowered into the basin, to fill the intermediate space with non-hardening slurry.

4. The device according to claim 2, wherein the control system is adapted to maintain the wet concrete surface level substantially level with the non-hardening slurry surface level during the filling of the product cavity with wet concrete and the intermediate space with non-hardening slurry, such that the pressure of the wet concrete against an inside of the outer wall of the form mould is substantially the same as the pressure of the non-hardening slurry against an outside of the outer wall of the form mould.

5. The device according to claim 2, wherein the control device is adapted to control the flow rate of a flow of wet concrete into the product cavity and/or to control the flow rate of a flow of non-hardening slurry into the intermediate space.

6. The device according to claim 2, wherein the device comprises a product mould transport frame, which product mould transport frame supports the product mould, wherein the slurry basin is configured for receiving the product mould transport frame supporting the product mould, and which product mould transport frame is adapted for cooperating with the lowering device, such that the product mould can be lowered into slurry held in the slurry basin by lowering the product mould transport frame into the slurry basin using the lowering device.

7. The device according to claim 1, wherein the control system is adapted to maintain the wet concrete surface level substantially level with the non-hardening slurry surface level during the filling of the product cavity with wet concrete and the intermediate space with non-hardening slurry, such that the pressure of the wet concrete against an inside of the outer wall of the form mould is substantially the same as the pressure of the non-hardening slurry against an outside of the outer wall of the form mould.

8. The device according to claim 1, wherein the control device is adapted to control the flow rate of a flow of wet concrete into the product cavity and/or to control the flow rate of a flow of non-hardening slurry into the intermediate space.

9. The device according to claim 1, wherein the device comprises a product mould transport frame, which product mould transport frame supports the product mould, wherein the slurry basin is configured for receiving the product mould transport frame supporting the product mould, and which product mould transport frame is adapted for cooperating with a lowering device, such that the product mould can be lowered into slurry held in the slurry basin by lowering the product mould transport frame into the slurry basin using the lowering device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 shows a schematic side view in cross section of a first embodiment of a device according to the invention;

(3) FIG. 2 shows a schematic perspective view in cross section of a second embodiment of a device according to the invention;

(4) FIG. 3 shows a perspective view of a third embodiment of a device according to the invention, in which the slurry basin is partially shown in cross section; and

(5) FIG. 4 shows a detail in cross section of the embodiment of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a schematic side view in cross section of a first exemplary embodiment of a device 1 for casting a concrete product according to the invention. The device 1 comprises a product mould 2, a slurry basin 3, a wet concrete supply device 4, a non-hardening slurry supply device 5 and a control system 6. The product mould 2 is partially filled with wet concrete 17, providing a wet concrete surface level 33, and the slurry basin 3 is partially filled with a non-hardening slurry 19, providing a non-hardening slurry surface level 34.

(7) The product mould 2 defines a product shape defining cavity 7, the cavity being delimited by an outer wall 8 of the mould. In the particular embodiment shown, the product mould 1 is substantially cylinder shaped a placed centrally in the cylinder shaped slurry basin 3.

(8) The product mould 2 is formed using a tube of flexible, sheet like fabric material 9. The sheet like material is suitable for contact with wet concrete, and provided with a coating to facilitate removing the sheet like material from a concrete product formed in the mould. The sheet like material 9 is fastened at its top end to a ring 12 secured on top of the basin 3, and at its bottom end to a second ring 13 lying on a bottom surface 14 of the slurry basin 3. The product mould is thus supported by the top of the slurry basin to prevent the product mould, more in particular the flexible sheet like material 9, from collapsing.

(9) It is noted that the product mould 2 has an open bottom, such that the bottom of the product cavity 7 is defined by the bottom of the slurry basin 3.

(10) It is noted that, when the bottom of the product cavity is defined by the bottom of the slurry basin, a sheet, foil, coating, etc. can be applied to the bottom surface of the slurry basin to prevent the wet concrete from adhering to the bottom surface of the slurry basin.

(11) In the embodiment shown, an insert 26 is provided in the product cavity. When the wet concrete has hardened in the product cavity, the insert forms part of the final concrete product. In the embodiment shown, the insert forms a foot of the final concrete product.

(12) In the embodiment shown the slurry basin 3 is provided with a bottom wall. In an alternative embodiment, the slurry basin comprises no bottom, and is positioned on an existing support structure, for example a floor element in a building. This is for example useful when casting a concrete product in situ, for example when casting a concrete product on a bracket that is partially received in an existing concrete floor element and which is to be incorporated in the final concrete product to be casted using the device according to the invention. In such an embodiment, the product mould is mounted on the floor element such that the bracket extends into the product cavity. The slurry basin can subsequently be raised around the product mould. In an embodiment, the slurry basin is provided with a flexible sheet to cover the surface of the existing support surface, e.g. a floor element, inside the intermediate space. Thus, the non-hardening slurry does not stain or otherwise influences the existing floor element. This technique can also be used for example for providing concrete support structures, for example for buildings, bridges, etc., in situ. These kinds of structures are often too large to be transported and thus are preferably made where they are to be used.

(13) It is noted that the use of inserts when moulding concrete products is known in the art, and that many types of inserts can be used with a device according to the invention. For example, an insert can be provided near the top of the product cavity which provides the final product with hooks or brackets for mounting the product. In a further embodiment, the product cavity is provided with inserts, for example Styrofoam blocks, that constitute a hole, being for example a door or a window, in the final product. In a further embodiment according to the invention, the product cavity can be provided with spacers to position for example the outer walls of the form mould relative to each other. Such an insert is for example temporarily attached to the wall of the product mould, to a positioning frame provided in the product cavity, or to an external support structure for supporting the insert, for example supporting the insert from above the product cavity. Other known types of inserts can be used.

(14) The product mould shown in FIG. 1 is furthermore formed using a first form element 10 and a second form element 11, both of material less flexible than sheet 9. The sheet material 9 is glued to the form elements 10, 11, such that flexible sheet material forms the surface of these form elements 10, 11. The first form element 10 is supported by the sheet like material 9, while the second form element is mounted via a bracket 15 to a wall of the basin 3. The bracket 15 and the wall of the basin thus form a positioning frame, that positions part of the support mould.

(15) The flexible sheet 9, support rings 12, 13 and form elements 10, 11 form the product shape defining cavity 7 to be filled with wet concrete that hardens in the cavity to form the concrete product.

(16) The slurry basin 3 in the embodiment shown is adapted to fully receive therein the product mould 2 such that an intermediate space 16 is present between a portion of the outer wall 8 formed by the sheet 9 and the first form element 10. The intermediate space 16 inbetween the non-hardening slurry basin 3, more in particular the slurry basin wall, and the product mould 2 almost covers the entire outer surface of the product mould 2, more in particular the outer surface of the outer wall 8 of the product mould 2. The part of the wall 8 of the product mould 2 formed by second form element 11 is covered by support bracket 15 of the product mould 2. The intermediate space runs along the surface of the outer wall 8 not covered by the support bracket 15.

(17) In FIG. 1, the product cavity is in the process of being filled. The wet concrete supply device 4 is adapted to feed wet concrete 17 into the product cavity 7 of the product mould 2. In the embodiment shown, the concrete supply device comprises an inlet in the form of a tube 20 for guiding the wet concrete into the product cavity. Alternative types of conduits and channels can be used. The concrete supply tube 20 is with one end connected to a wet concrete supply reservoir 24 (schematically shown). The tube is supported with its other end located in the product cavity 7. The wet concrete supply tube is provided with a valve 18 for controlling the flow of wet concrete 17 through the tube from the wet concrete supply reservoir 24 to the product shape defining cavity 7. In the embodiment shown, the concrete supply tube is lifted from the product cavity while the cavity is filled, preferably such that the tube outlet is kept just above the wet concrete surface level during the filling process.

(18) Lifting the inlet while filling the cavity can be achieved in many ways. For example, the tube can be provided on a reel which is turned by a motor drive to lift or lower the outlet end of the tube. In such an embodiment, the motor drive is connected to a control system monitoring at least the wet concrete surface level, or a representative thereof. Thus, the control system can keep the tube end at a constant position relative to the wet concrete surface level, for example just below or just above the wet concrete surface level, during the filling process.

(19) In an alternative embodiment, the concrete supply tube is kept stationary during the filling process and is only removed from the product shape defining cavity after the product cavity has been filled with wet concrete.

(20) The non-hardening slurry supply device 5 is adapted to feed a non-hardening slurry 19 into the intermediate space 16 between the outer wall 8 of the product mould 2 and the slurry basin 3, more in particular the inside surface of the slurry basin 3. In FIG. 1, the intermediate space is in the process of being filled.

(21) In the embodiment shown, the non-hardening supply device comprises an inlet in the form of a tube 21 for guiding the none-hardening slurry into the intermediate space. The tube is with one end connected to the non-hardening slurry reservoir 25 (schematically shown). The slurry supply tube 21 is supported with its other end located in the intermediate space 16. The slurry supply tube 21 is provided with a valve 22 for controlling the flow of non-hardening slurry 19 through the tube from the slurry reservoir to the intermediate space 16. The supply tube can remain in the intermediate space after it has been filled with non-hardening slurry since the slurry does not harden. However, similar to the tube for filling the product mould with wet concrete, the tube for providing the non-hardening slurry preferably is removed while the intermediate space is being filled.

(22) In the embodiment shown, the slurry basin 3 is provided with a slurry outlet in the form of a channel 27 and with a slurry outlet channel valve 28. In the Fig. the slurry basin and the mould cavity are being filled. The slurry outlet valve blocks the slurry outlet channel to allow for filing the intermediate space. After the product mould has been filled with wet concrete, and after the concrete has hardened, the slurry can be removed from the intermediate space via the outlet channel 27. Subsequently the product mould and the concrete product can be removed from the slurry basin, for example by opening the slurry basin or by lifting the product and product mould from the slurry basin.

(23) The control system 6 is schematically shown in FIG. 1. The control system can for example comprise a computer or pc. In the embodiment shown, the control system furthermore comprises control means in the form of sensors 23 provided in the bottom wall of the slurry basin, which sensors are pressure sensors. It is noted that in the embodiment shown, the product mould has an open bottom such that the bottom of the product cavity is defined by the bottom of the slurry basin. The pressure sensors in the part of the bottom of the slurry basin 3 that forms the bottom of the intermediate space 16 provide information on the pressure of the non-hardening slurry 19 in the intermediate space, and thus on the non-hardening slurry surface level 34. The pressure sensors in the part of the bottom of the slurry basin that forms the bottom of the form mould or product cavity provide information on the pressure of the wet concrete 17 in the product cavity 7 and thus on the wet concrete surface level 33.

(24) The control system 6 furthermore controls the wet concrete supply valve 24 and the slurry supply valve 25. Thus, the control system can adjust, i.e. reduce or increase the flow of wet concrete and non-hardening slurry.

(25) In the embodiment shown in FIG. 1, the control system is thus able to use the information provided by the pressure sensors at the bottom of the product cavity and the intermediate space to adjust the flow of the wet concrete and the flow of non-hardening slurry into the product cavity and the intermediate space respectively and to thus control the pressure below, and thus the surface levels in, the respective product cavity and intermediate space, while filling the product cavity with wet concrete and the intermediate space with non-hardening slurry.

(26) With a device according to the invention shown in FIG. 1 a concrete product can be provided by way of a method according to the invention.

(27) The device shown comprises a product mould 2, the product mould defining a product shape defining cavity 7 for receiving wet concrete to form the concrete product, and a non-hardening slurry basin 3, which slurry basin is adapted to receive the product mould 2.

(28) The slurry basin 3 is a tank like structure with a removable top. The top is removed for positioning the product mould in the slurry basin, and, after casting and hardening of the concrete, for removing the product mould and concrete product from the basin. The product mould is provided inside the tank such that an intermediate space between the slurry basin and at least part of the product mould is created. In the particular embodiment shown, the product mould and parts thereof are partially supported by the slurry basin. Thus, the outside wall of the product mould is almost over its entire surface in contact with the intermediate space.

(29) In the situation shown in FIG. 1 the product mould 2 has been positioned in the slurry basin 3. A non hardening slurry inlet tube 21 has been positioned in the intermediate space 16, and a wet concrete supply tube 20 has been positioned in the product cavity 7.

(30) Furthermore, the product cavity 7 is being filled with wet concrete 17 and the intermediate space 16 is being filled with non-hardening slurry 19 having a density substantially similar to the density of the wet concrete.

(31) While filling the product cavity 7 with wet concrete 17 and the intermediate space 16 with non-hardening slurry 19, the level difference between the wet concrete surface level 33 and the non-hardening slurry surface level 34 is controlled by a control system 6. The level difference between the non-hardening slurry surface level 34 and the wet concrete surface level 33 in the situation shown is substantially zero. Thus, the pressure of the wet concrete upon the inside of the outer wall 8 is balanced by the pressure of the non-hardening slurry on the outside of the outer wall 8. Thus, the flexible sheet like material of the product mould is not pressed outward or inward, and the final product will have a shape conform the product mould prior to filling it with wet concrete.

(32) During the filling of the product cavity and the intermediate space, the pressure in the wet concrete and the non-hardening slurry is measured near the bottom of the basin, and the flow of concrete and slurry into the respective product cavity and intermediate space is adjusted if necessary to keep the non-hardening slurry surface level and the wet concrete surface level substantially level. Alternatively or in addition, during the filling of the product cavity and the intermediate space, the wet concrete surface level and/or the slurry surface level in the respective product cavity and the intermediate space are directly measured while filling the product cavity and the intermediate space, for example using optical sensors or a floater type device.

(33) It is noted that as an alternative, the filling process can be executed and/or controlled by hand, for example by manually operating the inlet valves.

(34) When the filling of the product mould 2, and thus the filling of the intermediate space 16, have been completed, the supply tubes 20, 21 are removed from the product cavity and the intermediate space, and the wet concrete is left to harden. In the embodiment shown, the supply tubes are lifted during the filling process in pace with the rising surface levels, such that they are removed from the respective spaces when these are filled. After the filling process has been completed, the non-hardening slurry is left in the intermediate space until the concrete has sufficiently hardened. Subsequently the slurry is removed from the intermediate space via the slurry outlet channel 27 and the concrete product and the product mould are removed from the slurry basin.

(35) It is noted that in the embodiment shown, the product is removed via the top of the slurry basin. In an alternative embodiment for example the slurry basin comprises two parts which are secured, for example hingeably connected, to each other to form the basin. The parts can thus be separated from each other to open the basin and allow easy access to the slurry basin and to facilitate positioning a product mould inside the basin and removing a product mould and or product from the basin. Alternative embodiments are also possible.

(36) When the concrete product has been removed from the product mould, the concrete product is ready. However, it is possible that the concrete needs to harden further and/or further processing, for example treatment of the outer surface of the product, is required.

(37) It is noted that in an embodiment according to the invention, the product mould, or part thereof, remains part of the finished concrete product.

(38) FIG. 2 shows an alternative device according to the invention in perspective view, partially in cross section. In FIG. 2 those features which are similar to the ones of the device shown in FIG. 1 are provided with identical reference signs. The features are not again explained. In the embodiment shown in FIG. 2 pressure sensors are provided at the bottom surface of the product cavity and, at the same height, in the intermediate space. The pressure sensors and the control system are not shown in FIG. 2 but are similar to the ones shown in FIG. 1.

(39) The device shown in FIG. 2 differs from the one shown in FIG. 1 mainly in the construction of the product mould. In the embodiment shown in FIG. 2, the product mould comprises a frame 29, comprising a bottom, side walls and a top. The frame is self-supporting, made from flat wooden or metal plates, and simple in form. Within the frame, on opposite sides of the product cavity, two flexible sheets 30a 30b are mounted. The sheets are made of a plastic material having a thickness of about 0.2 mm. The sheets 30 are along their edges connected to the frame 29, for example using staples, tape and/or glue, such that the sheets form a curved surface. Furthermore, a positioning frame, in the form of ribs 31, is provided. The ribs are with their ends secured to the frame and extend along the outer surface of the sheets to correctly position them and further shape the mould. The function of these positioning ribs is similar to the function of the second form element 11 in FIG. 1, however, the sheets 30 are not fixed to the ribs but loosely lie against it.

(40) The product cavity shown in FIG. 2 is thus defined by the frame 29 and the sheets 30 supported by that frame and the support ribs 31. The product cavity is open along the top to allow filling of the cavity. Furthermore, the open top provides an air drain that prevents enclosed air to get trapped in the cavity during the filling process. It is noted that the intermediate space is also provided with such an air drain.

(41) In contrast with the product mould shown in FIG. 1, the product mould show in FIG. 2 is not supported by parts of the slurry basin. The product mould in FIG. 2 can thus be moved in and out of the slurry basin without demolishing it.

(42) FIG. 4 shows a detail in cross section of the embodiment of FIG. 2. Depicted are part of the intermediate space 16 and the non-hardening slurry 19 provided therein, part of the product cavity 7 of the product mould 2 and the wet concrete 17 provided therein, and the concrete supply tube 20. FIG. 4 furthermore depicts the wet concrete surface level 33 and the non-hardening slurry surface 34. It is noted that in the particular embodiment shown, the wet concrete surface level 33 is located slightly above the non-hardening slurry surface level 34. This creates a level difference 35, i.e. a vertical distance between the wet concrete surface level and the non-hardening slurry surface level.

(43) According to the invention this level difference is controlled during the filling of the product mould and the slurry basin, more in particular during the filling of the form cavity and the intermediate space. The level difference is controlled by controlling the wet concrete surface level and/or the non-hardening slurry surface level. By controlling the wet concrete surface level and the non-hardening slurry surface level the pressure in the wet concrete inside the mould and the pressure in the non-hardening slurry outside the mould are controlled. Thus, by controlling the level difference between the wet concrete surface level on one side of the wall of the mould and the non-hardening surface level on the opposite side of the wall, the pressure to which the wall of the mould is exposed to is also controlled. When the wet concrete surface level and the non-hardening surface level are level with each other, the level difference, i.e. the vertical distance between the two surface levels, is substantially zero and the pressure difference between the inside and the outside of the wall of the mould is also substantially zero. When the level difference is increased, the pressure difference between the inside and the outside of the wall of the mould is also increased. Due to this pressure difference the wall of the mould is displaced and/or exposed to stresses.

(44) According to the invention, the level difference is controlled such that pressure differences which may damage the mould are avoided. This can be done by keeping the level difference to a minimum, preferably substantially zero. It is noted that small pressure differences may be useful in correctly stretching the mould or positioning the wall of the mould during the filling process. Thus, small pressure differences may be provided during parts of the filling process, or be maintained throughout the filling process, to help the mould to keep its correct shape or to attain its correct shape.

(45) In the situation shown in FIG. 2 the product cavity 7 and the intermediate space 16 are both partially filled. It is noted that by providing a wet concrete surface level 33 slightly above the non-hardening slurry surface level 34, a slight over pressure is created inside the mould 8, more in particular inside the product cavity, and the sheets 30a, 30b are pressed outward and thus positioned and/or secured in their position against the positioning ribs 31 provided along the outside surface of the product mould.

(46) It is noted that the device in FIG. 2 is partially shown in cross section. Part of the slurry basin 3 has been removed to show the product mould 2 in the slurry basin and the non-hardening slurry in the intermediate space 16, and part of the foremost sheet 30a has been removed to show the wet concrete surface level inside the product cavity 7. In the product cavity an insert in the form of a framework 32 is provided to provide the final concrete product with additional structural strength. In a further embodiment according to the invention, the framework can also function as a positioning frame for positioning the walls of the product mould during the filling process.

(47) FIG. 3 shows a perspective view of a third embodiment of a device according to the invention. FIG. 3 shows a device 101 according to the invention, comprising a product mould 102, a slurry basin 103, a wet concrete supply device 104, a lowering device 105, a control system 106, and a slurry basin 103, partially shown in cross section.

(48) The product mould 102 comprises a round going form defining frame 137 and two outer wall sections 108. The frame 137 supports the outer wall sections 108 on opposite sides thereof. An inlet is provided at the top of the frame 137, which inlet is coupled to the wet concrete supply device 104. Inside the product mould 102 a product mould positioning frame 132 is provided to further position the outer wall sections 108.

(49) For example, the round going frame can be 3D printed and the wall sections can be a plastic sheet material. Alternatively, the entire mould can be 3D printed.

(50) The product mould 102 is provided in a product mould transport frame 100. In the particular embodiment shown the product mould transport frame 100 is a steel frame. Alternatively, the product mould transport frame can be made off for example wooden beams, plastic profiles, etc. The product mould transport frame 100 is configured to enable moving the product mould 102 and also functions as a product mould support for positioning parts of the product mould 102, more in particular for positioning the form defining frame 137 of the product mould 102.

(51) The product mould transport frame 100 and the product mould 102 are partially shown in cross section, such that the product mould positioning frame 132 and the wet concrete surface level 133 inside the mould are visible.

(52) In contrast with the embodiments shown in FIGS. 1 and 2, in the embodiment shown in FIG. 3 the product mould 102 is lowered into the non hardening slurry basin during the filling of the product mould with wet concrete. Therefore the product mould is provided in the product mould transport frame 100. The product mould transport frame, and thus the product mould, is supported by a crane like lowering device 105. The product mould transport frame furthermore supports the wet concrete supply means 104, which are configured for providing a flow of wet concrete into the product cavity of the product mould.

(53) In the particular embodiment shown, the product mould is closed along its top side. Providing the mould with an at least partially closed top end allows for casting products having a curved top surface. Furthermore, when the product mould is fully closed along its top end it can be fully submerged into the slurry. Thus, when the product mould is fully filled with wet concrete, the non-hardening slurry surface level 134 can be raised above the top of the product mould 102.

(54) In the embodiment shown, the control system 106 is linked to the lowering device 105 and the wet concrete supply device 104. The control device is furthermore provided with sensors (not shown in the Fig.) located on the product mould transport frame 100 to monitor the non hardening slurry surface level 134 relative to the product mould transport frame, more in particular relative to the product mould during the lowering of the product mould into the non hardening slurry. The control system 106 can adjust the flow rate of the wet concrete and/or the speed at which the product mould 102 is lowered into the non hardening slurry to control the distance between the wet concrete surface level 133 inside the product mould and the non hardening slurry surface level 134 in the slurry basin 103, for example keep them substantially level or at a constant level difference of 2 cm, during the filling process. Preferably, the control system is provided with control means for monitoring the wet concrete surface level, and the rising thereof, inside the product mould during the filling and lowering into the slurry of said mould.

(55) It is noted that it is also possible to add slurry to or remove slurry from the non hardening slurry basin while the product mould is lowered into the slurry.

(56) For example, in an alternative embodiment, the non hardening slurry basin is provided with slurry removal means, for example a pump or an overflow, to keep the non hardening slurry surface level at a constant level. Such a slurry basin is filled with non hardening slurry up to a level sufficient for submerging the product mould in the non hardening slurry. When the product mould is lowered into this slurry basin, while being filled with wet concrete, the non hardening slurry replaced by the product mould and wet concrete is removed from the slurry basin, keeping the non hardening slurry surface level in the slurry basin at a constant level. Thus, in such an embodiment, the non hardening slurry surface level is known and does not need to be monitored by the control system. Thus the control system only needs to actively control the lowering of the product mould into the non hardening slurry and or the flow of concrete into the product mould, to keep the wet concrete surface level at a correct position relative to the non hardening slurry surface level, for example level with the non hardening slurry surface level.

(57) The particular product mould transport frame shown in FIG. 3 is of a cage like configuration, enclosing the product mould. Alternatively, the transport frame can only partially enclose the product mould.

(58) On top the product mould transport frame 100 shown in FIG. 3 is provided with connecting means 136 for cooperating with the crane type lifting device 105. In the particular embodiment shown the product mould transport frame is provided with a ring type fastening device to be engaged by a hook of the lifting device, to enable lifting and lowering the product mould transport frame into and out of the non hardening slurry basin using the lifting means.

(59) In another embodiment, the product mould is configured such that it can be directly supported by lowering device, and the product mould transport frame is absent. In another alternative embodiment, the product mould is supported on a foot plate, which is provided with fastening means for coupling with a lowering device.

(60) Preferably, the product mould is provided with a product mould transport frame to facilitate moving the product mould. When providing the product mould with a product mould transport frame, the product mould can be comparatively delicate and of a complicated design, while the product mould transport frame is comparatively firm, for example be made from wood ore steel profiles, and of a simple design. The product mould transport frame is for example provided with coupling means for cooperating with a lowering and/or a lifting device for lowering and/or lifting the product mould transport frame, and thus the product mould, into and/or out of the non hardening slurry basin.

(61) The non-hardening slurry preferably closely matches the concrete in all aspects but the hardening. Like wet concrete, the slurry comprises a coarse aggregate, sand and water. The non-hardening slurry preferably has a density substantially similar to the density of concrete. In an embodiment the non-hardening slurry matches the mass and the viscosity of the wet concrete. In an embodiment, the non-hardening slurry also matches the thixotropic properties of the wet concrete. In an embodiment, the non-hardening slurry comprises a mixture of natural gravel, sand, betonite, barium sulfate and water, for example, for one cubic meter of slurry, 865 kg natural gravel, 860 kg sand, 25 kg bentonite, 175 kg barium sulfate, and 235 liters water. Bentonite is added for mirroring the characteristics of cement in the wet concrete, in particular to copy the thixotropic characteristics of the wet concrete. For fine tuning the specific mass of the non-hardening slurry, a high density material like barium sulfate is added.

(62) In an alternative embodiment, one cubic meter of non-hardening slurry comprises a mixture 27 kg bentonite, 1500 kg barium sulfate, 630 liters water and no gravel or sand. Such a mixture is in particular suitable for use with a device according to the invention in which the product mould is lowered into the slurry during the filling of the product mould with wet concrete.

(63) Other configurations of the slurry are also possible.

(64) It is noted that non-hardening slurries that match the properties of wet concrete are known in the art. It is believed that the common general knowledge of the skilled person and the information provide in this text provide the skilled person with sufficient information to enable the skilled person to provide a non-hardening slurry that sufficiently matches the properties of wet concrete to be used to cast a product.

(65) In an embodiment, the wet concrete is self-compacting, and the slurry matches the properties of the self-compacting wet concrete. The self-compacting concrete needs no additional supply of compacting energy, such as mechanical stifling of the wet concrete. Thus, the risk that a disturbance in the hydrostatic pressure, caused by the applied compacting energy, would lead to a deformation of the outer wall of the product mould, and thus to a deformation of the final product, is reduced.

(66) A device and method according to the invention can be used to manufacture concrete products of different size and shape, for example concrete objects which are round, circular, square, rectangular or are any other well-defined linear or symmetrical shape, such as walls, floor slabs, pillars, tiles and a few other constructional elements. The invention allows for a simplified construction of the formworks or product mould. The device and method according to the invention are therefore especially beneficial when manufacturing concrete product with a non-flat surface, for example a curved or wave like surface.

(67) In an embodiment, the device according to the invention is provided with a product mould that is shaped to mould a concrete product that constitutes a beam or beamlike structure, having a rectangular, square, circle, ellipse, or polygon cross-section. In another embodiment, the mould is shaped for providing a concrete object having an irregular cross section.

(68) It is furthermore observed that since the hydrostatic pressure exerted by the wet concrete and the non-hardening slurry on opposite sides of the outer wall of the product mould is substantially similar, the risk of leakage and the wet concrete flowing from the mould is substantially eliminated. Also for this reason, the construction of the mould is less critical.

(69) It is noted that with a device according to the invention, the slurry basin has to be able to support the volume of wet concrete and non-hardening slurry. The basin is thus comparatively heavy build compared to the product mould which is subjected to minimal pressures only. The slurry basin however can be of a simple design, for example box or cylinder shaped, and can be used with multiple form moulds. The form moulds can be of a complicated design. However, since the product mould does not need to support substantial pressures, it can be made of simple, light weight, and flexible materials. The product mould is thus easy to assemble. The combination of a slurry basin with a form mould according to the invention thus provides a fast and low cost way to manufacture curved concrete products, in particular concrete products of different shapes.

(70) It is noted that for providing support to the product mould, the non-hardening slurry surface level in the slurry basin is relevant. The slurry basin can thus in principle be provided in any kind of size and shape suitable for holding one, or more, product moulds. In a preferred embodiment, the basin has a rectangular lay out with a flat bottom floor. Preferably, the basin is dimensioned such that, when a product mould is placed in the basin, the volume of the intermediate space is substantially similar or smaller than the volume of the mould cavity.

(71) In an embodiment, the slurry basin has a rectangular lay out with a width of about 1 m, for example 0.8 m, a length of over 5 m, for example 8 m and a depth of over 3 m, for example 3.6 m. Other dimensions and/or ratios are possible. For example, the basin can be provided with a rectangular floor surface.

(72) In an embodiment, the slurry basin is built up out of standard modular panels as are commonly used in falsework for wall type constructions. In this embodiment these panels constitute a barrier for the slurry.

(73) The product mould can be provided in different kind of shapes, as long as the height of the product to be made is not larger than the depth of the basin. The form mould is preferably placed on the bottom floor of the slurry basin. However, it is also possible to for example hang the product mould in the basin from an overhead crane, or support the product mould in the basin with a support structure.

(74) In an embodiment, the product mould has a curved surface and an overall width of less than 1 m, for example 0.2 m, and an overall height of more than 3 m, for example 3.6 m. Other dimensions and/or ratios are possible.

(75) In an embodiment, metal sheets with a thickness of 2.0 mm are used to form a product mould for a typical one story high building element. By supporting the metal sheet walls of the product mould with the non-hardening slurry according to the invention, additional supports in the form of for example elaborate scaffolding or traditional formworks can be avoided.

(76) It is noted that a slurry basin of a device according to the invention can be used with moulds of different shapes and sizes, as long as they fit in the basin. When the form mould is substantially smaller than the basin, inserts, for example Styrofoam or wooden blocks, can be placed in the basin to reduce the volume thereof. Thus the difference between the volume of the basin and the volume of the product cavity is limited. This facilitates filling both at a substantial similar speed. Furthermore, the over-all volume of non-hardening slurry needed for filling the basin is reduced.

(77) It is noted that according to the invention filling the intermediate space in pace with the filling of the product cavity provides a counter pressure build up on the outside of the outer wall of the product mould that matches the pressure build up on the inside of the outer wall of the product mould. Such a pressure build up is not possible when the intermediate space is filled prior to or after filling the product mould with wet concrete, and/or when the intermediate space is filled with a fluid such as a gas or a slurry that not substantially matches the properties of the wet concrete, such as water.

(78) In an embodiment according to the invention, the non-hardening slurry or the wet concrete is provided at a pre-determined volume per minute, and respectively the flow of the wet concrete or the non-hardening slurry is controlled, and if needed adapted, to control the level difference between the respective surface levels.

(79) Furthermore, the product mould of a device according to the invention only defines the shape of the product to be made, and does not need to support the weight of the wet concrete in the product cavity. Therefore the mould design can be kept simple.

(80) Also, because the product mould according to the invention does not need to support the weight of the wet concrete, changes to the shape of the mould do not require a redesign of the overall product mould to prevent collapse when filled with wet concrete. A device according to the invention thus enables the use of moulds of which the form cavity can be changed without much effort and thus enables the production of a great variety of products in less time and/or against lower costs when compared to known formworks.

(81) In this text the terms form mould and product mould are considered interchangeable because they relate to the same feature of the invention, i.e. the mould that shapes the final product.