Field of the Invention

The present invention relates to a method of manufacturing a panel made from a cement-based material as well as a mould for using that method. The method is particular in that it provides a finished cement-based panel having mould sides/surfaces on both the front and back side as will be discussed and described in further detail below.

This application concerns a method as well as a mould where a cement-based hardenable material is used. For the sake of the description and the embodiments mentioned below, reference will be made to concrete, and in particular a high strength concrete, but it should be understood that any type of material having hardenable properties and preferably involving a cement used as a hardening agent will be contemplated within the scope of the present invention.

Background of the Invention

Traditionally, when casting concrete panels such as used for wall panels, a mould is used into which the substantially fluid hardenable material is poured or sprayed onto the surface. Prior to pouring or spraying of the concrete, reinforcement, inserts etc. may be placed in the mould. The mould typically comprises a bottom mould plate typically made from a smooth steel plate or a wood plate as well as side limitations also made from either steel or wood. Prior to casting the liquid concrete, the mould sides are usually provided with a release agent in order to make the mould release a semi- hardened concrete panel relatively easy such that the moulding does not in any way damage the panel, and the mould is not exposed to excessive force. After the concrete is poured into the mould, the exposed upper surface of the concrete is usually finished either by manual means or by machine means in order to obtain a substantially smooth, flat, and even surface. These upper surfaces will never obtain the same kind of finish as the lower surfaces or the surfaces in contact with the mould. One reason for this is the fact that during the pouring of the concrete and/or immediately after the pouring of the concrete, the mould will be exposed to vibrations in order to distribute and compact the concrete evenly in the mould and in order to let the air trapped between the mould and the concrete escape along the mould sides or into the concrete as such. Furthermore a liquid containing fine particles and water will migrate to the surface layer immediately adjacent the mould, and will result in an extremely smooth surface. In this manner a very even, smooth and substantially closed surface is obtained in the concrete facing the mould sides. This surface is therefore substantially different than the surfaces which are manually or machine finished, i.e. not mould sides.

For a number of applications it is desirable to have mould sides on both sides of the finished wall and for these purposes sandwich elements are made where for example two panels are manufactured as described above and then after the casting process, they are connected such that the mould sides will be facing the exterior and thereby providing the impression that mould sides are present on both sides. In this procedure, there is a number of disadvantages, one of the major disadvantages being that, in practice in order to manufacture one concrete panel, two concrete panels need to be manufactured and finished in order to provide the desired outcome.

Object of the Invention

Consequently, it is an object of the present invention to address this and other problems.

Description of the Invention

The invention addresses this object by proving

. Method of manufacturing a panel made from a cement-based material, where said method comprises the following steps: a mould is prepared, where said mould comprises two mould plates, each plate pivotably connected to the sides of a middle beam along one side of said plates, and where, along the other sides of the mould plates, side limitations are provided;

placing said mould such that the mould plates and the middle beam are substantially in the same plane;

placing a layer of cement-based material onto the mould surfaces, middle beam and optionally side limitations; folding the mould by the pivot means, such that the mould plates are folded into a substantially parallel position whereby the cement-based material covered surfaces are facing each other, and substantially perpendicular to the middle beam while the cement-based material is still fresh and non-hardened;

allowing the cement-based material to harden, and hereafter the mould is removed.

By providing a mould with pivotable mould plates it becomes possible to deform the mould after a concrete is placed and thereby alter the shape of the mould after the concrete has been placed. This naturally puts restrictions on the concrete placed in the mould in that the concrete must be sufficiently viscous such that the concrete, at least during the folding of the mould will not tend to slide down the mould. By providing the pivot means, for example in the shape of hinges below the mould plates, the folding action will provide a very clean corner construction, as will further be elaborated with reference to a particular embodiment of the invention.

In this way a panel created by using the described mould and method to form a unique two sided extremely strong and ductile panel or strong and insulated panel, with 2 perfect surfaces.

In a further advantageous embodiment of the invention, the placing in step ii is carried out by spraying said material onto the mould plates. In addition to achieving that the cement base material, for example a concrete, adheres to the mould plate, it is also achieved that the surface due to the spraying up of the concrete becomes very compact and smooth, and as such a very good result may be obtained by this technology. The sprayed layer may be as thin as a couple of millimetres and will need no further compaction or vibrating to obtain perfect surfaces.

It is particularly advantageous to use a high strength concrete for spraying as the resulting surface in addition to the extremely smooth surface also will be very dense and compact and as such will be very protective against the influences of the environment. This in turn provides a long lasting surface with a minimum of maintenance.

In a further advantageous embodiment of the invention, the middle beam has a length corresponding to the extent of the mould plates, and the width of the beam is greater than the combined thickness of the sprayed layers, and where, before step iv, a further step is added in which a second substantially rigid material is placed perpendicularly on the beam, such that when the mould plates are folded in step iv, the rigid material is sandwiched between the plates. In this embodiment of the invention, it is in particular advantageous where the spray technique is used in that it becomes possible to spray very thin layers and still achieve very high finishes, and by using high strength concrete also very strong surfaces are achieved. Therefore, by folding the mould around a rigid material, a sandwich structure is obtained. The rigid material may, as disclosed in a further embodiment, be selected among insulating panels, reinforcement structures, a honeycomb structure, etc. The honeycomb structure is made from thin but relatively wide strips assembled in a honeycomb. The structure will not directly provide strength, but due to the moment of inertia/resistance provided by the distance between the two opposing concrete layers, it will provide stiffness and at the same time it will provide a very light construction. Naturally, by filling with any insulating material, or inserting an insulating panel as the rigid material and in particular a vacuum insulation, very thin, rigid, strong, and highly insulating panels may be obtained with very limited thickness dimensions.

In a further advantageous embodiment, the middle beam has a middle section extending out of the plane attained in step ii, and where said middle section is arranged along the length of the beam. The middle section serves to provide a groove in the finished panel which will be useful for establishing joints between panels and/or tightness and other constructional details depending on the shape of the middle section.

In a still further advantageous embodiment of the invention, the middle beam has a length corresponding to the extent of the mould plates, and where the width of the beam is greater than the combined thickness of the sprayed layers, and where, after step iv, a further step is added in which a second material is placed in the space limited by the beam, the mould plates, and the side limitations.

In this manner, it is obtained that the large side surfaces of the finished panel will have a finish as a mould surface, whereas the centre of the panel is poured, for example by pouring a reinforced Ultra High Performance Concrete, normal concrete, a light weight concrete, or an expanding concrete, or a foam, such that the resulting concrete panel becomes a extremely strong and ductile panel and/or a highly insulating sandwich panel having two mould surfaces. Especially in an embodiment where the layers which on contact with the mould plates are sprayed and in particular sprayed with a high strength concrete, very light weight and though high strength concrete panels are achievable by this method.

The top part of the mould, where the top mould part is positioned, provides that only the concrete placed in the second gap in the top mould does not exhibit a mould surface and as such obtain a very smooth finish.

In a further advantageous embodiment of the invention, a second gap has a distance between the two sides which is equal to or smaller than the width of the middle section of the middle beam. With these geometrical relationships, it is possible that the tongue is created by the concrete material placed in the second gap where the tongue is insert- able in the groove provided by the middle section of the middle beam, and in this manner a very traditional but yet a rigid, stable and well-proven method of connecting two concrete panels is provided. Furthermore, since all surfaces, except the top surface of the material placed in the second gap in the top mould part, are to be considered as mould surfaces, a very smooth and homogenous panel is provided with comparatively small tolerances such that a high degree of finish and assembly of light panels may be obtained.

In some embodiments it is desirable to connect front and rear plates, and therefore, in a further embodiment of the method, the invention provides that, after step iii, connectors are placed lightly embedded in the fresh sprayed material layer, such that, when the mould is folded in step iv, the connectors will be slightly embedded in the material lay- ers sprayed onto both mould plates. The connectors will naturally be selected such that their length is not longer than the distance between the mould plates when they are in the folded state. Therefore, in an embodiment where the mould plates are provided with a thin spray of for example a high strength concrete, the connectors are very short such that they will be lightly embedded in the sprayed concrete layer on one mould side, and as the mould is folded the connector will embed itself in the concrete on the other side. In another embodiment where insulation or a further material is poured between the two mould sides, the connectors shall be provided with an appropriate length in order to achieve the desired connection between the front and rear sides of the panel.

If desired any type of reinforcing mesh or bars made of steel, glass fibre, Carbon, basalt etc. or any type of reinforcing fibres for concrete can be used in the space between the two sides of the panel to improve strength and ductility of the panel. In certain embodiments, it will furthermore be necessary taking into account the very thin concrete layers used with the spray technique and/or high strength concrete to further strengthen the embedding of the connectors, for example by spraying a little extra material around the connectors embedded in the concrete layer. The invention is also directed to a mould for use in a method as discussed above where the mould comprises two mould plates, where each mould plate along one side of respective plates is pivotably connected to a middle beam, allowing said plates to pivot relative to said beam, thereby folding the mould into a folded state, and where the other free edges are provided with side limitations.

Further embodiments of the mould are disclosed in the dependent claims, but naturally the mould will have all the features which are necessary in order to carry out the method disclosed above. Description of the Drawing

The invention will now be explained with reference to the accompanying drawings wherein Figure 1 illustrates an example of a mould according to the present invention.

Figure 2 illustrates a mould where the mould plates may be pivoted into position by means of hinges.

Figure 3 illustrates a further embodiment where the mould sides of the mould plates 2, 3 in the mould positions illustrated with reference to figure

1 have been sprayed with a thin layer of high- strength concrete 10 on all mould surfaces including the side limitations 5, 6.

Figure 4 illustrates a further embodiment of the invention where the middle beam 4 is very narrow.

Figure 5 illustrates an embodiment where the mould side plates 2, 3 are sprayed with concrete and folded into upright position.

Figure 6 illustrates a mould provided with a further top mould 20.

Figure 7 illustrates a panel 50 manufactured according to the invention.

Figure 8 illustrates part of a mould 1 according to the invention.

Figure 9 Illustrate a cross-section through a mould combining unique concrete surfaces combined with reinforced Ultra High Performance Concrete in the space between the exterior surfaces.

Detailed Description of the Invention

In figure 1 is illustrated an example of a mould according to the present invention. The mould 1 is illustrated in its unfolded state where two mould plates 2, 3 are pivotably connected to a middle beam 4 along one side of each mould plate 2, 3. In this manner the two mould plates 2,3 and the middle beam are substantially in the same plane. The pivot may be provided by a hinge or the like. Along the three other sides of the mould plates 2, 3 side limitations 5, 6 are provided. Although the side limitations are not illus- trated on the third side it shall be understood that these have been removed for illustrative purposes. By means of the hinges 7 the mould plates 2, 3 may be pivoted into the position illustrated with reference to figure 2, i.e. where the mould plates 2, 3 are raised into a substantially vertical position and where the mould plates 2, 3 are parallel and perpendicular with respect to the middle beam 4.

In figure 3 is illustrated a further embodiment where the mould sides of the mould plates 2, 3 in the mould positions illustrated with reference to figure 1 have been sprayed with a thin layer of high- strength concrete 10 on all mould surfaces including the side limitations 5, 6. In this embodiment the side limitations 5', 6' are special in that they are provided with flanges 11, 12. Furthermore, an insulating panel 13 has been placed on a middle section of the middle beam 4 substantially parallel to the mould sides 2, 3. In this position the mould 1 is ready to be filled with a further filling material in the space provided between the high strength concrete layer 10 and the insulating panel 13.

As the mould is filled, the filling material, typically a concrete, will finally fill the mould 1 until the top edges of the flanges 11, 12. In this manner only the surface between the free edges of the flanges 11, 12 will not be mould sides, and as such a completely finished panel is provided.

By furthermore providing a middle beam 4 having a middle section 4' which is larger in the direction perpendicular to the plane of the panel, and where the distance between the two flanges 11, 12 is smaller than the width of the central part of the beam 4' a groove and tongue connection is provided such that when assembling the panels manufactured according to the inventive process these may be assembled for example by placing one panel on top of the other such that the tongue on one panel fits into the corresponding groove on an adjacent panel.

In figure 3 an insulating panel has been placed on the middle beam between the two side mould plates 2, 3, but any type of material may be placed and thereby be part of the panel (sandwich) structure.

In figure 4 is illustrated a further embodiment of the invention where the middle beam 4 is very narrow such that as the mould side plates 2, 3 are sprayed with concrete and folded into upright position as illustrated with reference to figure 5, the sprayed layers will come into contact thereby providing a very thin substantially massive panel having sprayed surfaces and therefore do not need any further manual finishing work.

It is contemplated within the scope of the present invention that the middle beam and the side limitations may have any desired dimensions in order to produce panels ac- cording to the inventive method such that panels are provided with mould sides on both sides due to the foldable structure of the mould as described above with reference to for example figure 1. In further advantageous embodiments of the invention a mould may as illustrated with reference to figure 6 be provided with a further top mould 20. In addition to the middle beam 4 the side mould plates 2, 3 and the upstanding flanges 11, 12 the mould is provided with a top mould 20 which also is provided with two parallel flanges 21, 22. The distance between the flanges 21, 22 is larger than the distance between the flanges 11, 12 such that the top mould may be fitted on top of the side limitations 5', 6' and the flanges 11, 12.

Alternatively, the top mould may have an extent perpendicular to the plane of the panel, such that the flanges 21,22 may fit on the outside surfaces of the side mould plates 2,3 in the moulds folded state. In this version of the invention the top side limitations may be dispensed with, if the finished panel does not need sprayed surface characteristics in that area.

In this manner it becomes possible to cast the concrete panel where also a large part of the tongue, see figure 7, has mould sides and only very small sections of the overall surface of the panel has to be manually finished. In figure 7 is illustrated a panel 50 manufactured according to the invention with a mould system as described above. The surfaces of the panel 50 which have been in contact with the middle beam 4, the side mould plates 2, 3 and the side limitations 5, 6 as well as the flanges 21, 22 are all very smooth and normally do not need any further finishing work, but will appear to be mould sides. Consequently, only the upper part 51 which has not been cast against a mould will need some finishing. As the tongue 52 will typically be fitted inside the groove 53, the finish of the top surface 51 of the tongue is not that important in that all exposed surfaces such as for example the side surfaces 54, 55, 56 all will appear with a superior finish. In order to make use of a mould system as described above in order to manufacture a panel as schematically illustrated in figure 7 the procedure comprises the following steps. Initially the mould is arranged in a position as illustrated with figure 1, and a suitable mould release agent may be provided on the surfaces of the mould which are to be sprayed with the concrete material, for example the surfaces of the middle beam 4, the mould side plate surfaces 2, 3 and the side limitations 5, 6. In this position the side mould plates 2, 3 and the middle beam are substantially arranged in the same plane. After this, a layer of cement-based material is places onto the mould plate surfaces 2, 4, 3, 5, 6 (for example by spraying) such that the interior sides of the mould are completely covered with a concrete material. A preferred method is a spraying technique spraying a high strength concrete optionally provided with fibre enforcement, against the mould sides. Typically the layer thickness will be from a couple of millimetres up to 20- 25 millimetres. After having placed the concrete in contact with the mould sides and the middle beam, the mould side plates 2, 3 are pivoted by means of the hinges 7 into a substantially vertical position relative to the middle beam as already illustrated and described above with reference to figure 2. Before this process is carried out it should be ensured that the concrete arranged against the side limitations and the mould side plates has set sufficiently such that it will not flow down the mould sides due to the influence of gravity or the like. In embodiments where a thin massive concrete panel as illustrated above with reference to figure 5 is to be manufactured the sprayed concrete layers will come into contact with each other and after the concrete has set sufficiently, the mould may be unfolded again in order to remove the finished panel.

In other embodiments the process includes placing an insulation layer on the middle beam prior to folding the two side mould plates 2, 3 such that an arrangement as illus- trated with reference to figure 3 is achieved.

It should also in this context be noted that although the embodiment in figure 3 is described with reference to an embodiment where a further material is filled into the mould the middle beam 4 may also be dimensioned such that as the side mould plates 2, 3 are folded, the sprayed layer 10 will come into contact with the rigid plate 13 arranged on the central section 4' of the middle beam 4. In figure 8 is illustrated part of a mould 1 according to the invention. The mould is in the open state, i.e. where the two mould plates 2, 3 and the middle beam 4 are arranged in the same plane. A thin layer of sprayed concrete 10 (indicated by edged marking) has been arranged on the interior surfaces of the mould sides. Embedded in the thin layer of concrete 10 are connectors 58. The connectors are arranged such that they will project substantially perpendicular to the sprayed surface 10. The length of the connectors is selected such that as the two mould side plates 2, 3 are folded into position as schematically illustrated with reference to figure 3, i.e. by pivoting around the hinges 7. The free end of the connectors 58' will be embedded in the concrete arranged on the opposite mould side plate in this instance the mould side plate 3. In this manner it becomes possible to connect the two outer layers of concrete on the finished panel. Where an insulation is to be arranged between the two sides of the panel, the insulation, for example as illustrated with reference to figure 3, may be provided with apertures such that before the mould side plates 2, 3 are folded, an insulation material is arranged on top of the sprayed concrete where the apertures are superposed the connectors 58 which thereby will extend through the insulation material.

In a further embodiment of the invention, a cross-section through a very strong panel 22 in the mould 1 is illustrated see fig. 9. The panel has thin layers 10 of high strength concrete sprayed onto the mould sides 2, 3, such that as the mould is removed the sprayed surfaces will constitute the outside of the panel 22. After having sprayed the layer 10 in the mould 1, a reinforcement, for example a resin covered glass-fibre reinforcement 23, is arranged in the space between the sprayed surfaces facing the inner part of the mould. Finally an ultra high performance concrete 24 is filled into the void inside the mould.

After curing the mould may be removed, to expose a panel with superior surfaces due to the spraying process, and exceptional strength characteristics due to the ultra high performance concrete 24. Above, the invention has been described with reference to a few embodiments, but the invention should only be limited by the scope of the appended claims.