This invention relates to a for worϊ system comprising first and second plate means forming therebetween a casting space for concrete or the like, and having a number of spacers, at least one of the plate means and the spacers being adapted to be incorporated into a finished wall after casting.

The formwork system can be heat insulated or not insulated and in practice can advantageously be made of first wall plates of natural gypsum and of second wall plates of woodwool-concrete, or alternatively sewage and/or industrial waste, which are interconnected for example by hook-like spacers. When a formwork based on this system is erected, it is ready to be filled with concrete in which sewage and/or industrial sludge can be added.

On the background of strong trends in the environmental field as regards the consumption and deposition of waste or sludge from various purification and industrial plants, as well as the formidable expenses involved in apartment and building projects, there are here described very advantage¬ ous solutions for coping with these problems.

Austrian patent 389.667 describes a formwork system having internal and external panels, spacers between these panels and heat insulation incorporated. This known struc¬ ture however, involves problems and drawbacks in particular related to the handling, the assembling and building up of a formwork, mainly because of the connection members or spacers shown, these being cast into one of the concrete panels which are included in the structure. Among other things there is a high risk of damaging the integrated spacers during transport and handling.

On this background and taking as a starting point the formwork system as generally recited in the first paragraph of this description, the novel and specific features

according to the present invention consist therein that the first plate means comprise first plate elements having groove and tongue profiles along at least the edges which are adapted to lie horizontally upon mounting, that the first plate elements have such thickness that the first plate means alone can stand with required stability, that first spacers are adapted to co-operate with the groove and tongue profiles and have coupling members adapted to project into the casting space, that the second plate means comprise second plate elements having longitudinal edges adapted to lie horizontally and substantially level with said edges on the first plate elements, and that second spacer elements are adapted to be anchored between said longitudinal edges on the second plate elements and to project into the casting space with coupling members shaped so as to engage the coupling means on the first spacer elements.

Further novel and advantageous features of the system according to the invention will appear from the following description and the claims.

In a possible practical embodiment this formwork system can consist of two wall plates which are held together by a hook arrangement. Thus there is established a cavity between the wall plates in which sanitary and electrical installations are located (so-called hidden installation) . Then this cavity is filled with concrete. Moreover this cavity has room for a desired choice of insulation layer (isopor, polyurethane, etc.). Reinforcement iron is put in according to current standards for reinforced concrete. First the interior plaster elements are stacked (horizon¬ tally) to the height of one storey. Then the sanitary and electrical installations are carried out, which is much simplified since there are no physical obstructions. When the installation work has been performed, the exterior wall elements are stacked. When the stacking or erection of interior and exterior wall plates has been carried out and after arranging the desired installations, the cavity is filled with concrete, and thereby the load supporting, static properties for any kind of building and load are

obtained. Such a concrete-filled formwork system excludes the possibility of thermal bridges, and the fact that the insulation layer is located in the interior of the system but outside the concret mass, and not vice versa as in the case of more common constructions, is hightly advantageous. The cost level and the time of erection of an apartment or building besides will be strongly reduced.

As a consequence of the material composition of the formwork system it is possible to saw, screw or nail directly into the wall plates. Moreover the formwork system will result in a high safety against fire, at the same time as such a formwork system is very favourable to the environ¬ ment. The exterior wall plates can be plastered or provided with a panelling respectively. The internal wall plates can be kept without treatment or possible painted, panelled, provided with wallpaper or tiles etc.

The internal or first wall plate is suitably made of pure natural gypsum and this wall plate besides has groove and tongue profiles which simplify the erection. The mounting of these internal plasterboard walls is performed with gluing by means of a sealant.

The dimensions of a plaster board can be for example : height = 50 cm, length = 66,6 cm and thickness = 60, 80 or 100 mm. The thickness of the plaster elements employed is primarily determined by the height of the building con¬ cerned. Such plasterboard elements have been produced and been commercially available for many years.

For the exterior wall plates there are two alter¬ natives: either a woodwool-concrete wall plate or a wall plate of sewage and/or industrial sludge. Such a woodwool- concrete wall plate is know in various embodiments and thus does not represent any new component per se. On the other hand the second alternative with a wall plate of sludge concrete is a novel proposal. This wall element is manufac¬ tured mainly of sewage and/or industrial sludge to which a proportion of fibre (woodwool) , lime and/or cement is added. The material composition can favourably be substantially as

described in international patent application PCT/NO90/00102.

The dimensions of the wall plate both of woodwool- concrete and of sewage and/or industrial sludge with fibre (woodwool) lime and/or cement addition, can be : height = 50 cm, length = 200 cm and thickness = 3,5 - 5 cm. These dimensions are chosen in relation to the above examples of the dimensions of the plaster boards. The height of the building concerned essentially determines the thickness of the exterior wall elements.

The connection members or spacers between both wall plates are divided into two parts, of which the one part being attatched to the plaster element (i.e. the interior wall) , is adapted to the groove and tongue of the plaster board and has a projecting part for example shaped as a simple hook. The other part has an eyelet or a hook at one end (to be connected to the hook at the plasterboard wall) . At the other end this part has a H-shape, and thus the exterior wall elements are put down into this H-part of the connection member. The lengths of the joined connection members depend on the thickness of the interior and exterior wall elements as well as the amount of concrete (i.e. the thickness thereof) to be filled into the cavity established between the interior and exterior walls. The connection members or spacers can be made of a plastic material or metal.

When filling concrete into the cavity of the formwork system it is often an advantage to employ sewage and/or industrial sludge; i.e. to the degree the concrete will thereby maintain mechanical strength properties being sufficient for the building. Such concrete based on sludge is obtained by somewhat modifying the regular composition which is sand, concrete and water. The sand proportion is reduced and sewage and/or industrial sludge is added without significantly reducing the strength of the concrete. Thus the new composition will be sewage and/or industrial sludge, sand, cement and water. As above reference can here be made to international patent application PCT/NO90/00102 which

describes suitable material compositions also for the casting mass (concrete) .

The invention shall be explained more closely in the following description with reference to embodiments shown in the drawings, in which: fig. 1 somewhat schematically and in perspective view shows two plate means with associated spacers or connection members, for erecting a wall formwork, fig. 2 shows a smaller section and somewhat more in detail a second and preferred embodiment of the formwork system according to the invention, and fig. 3 shows the design of a first spacer element incorporated in the structure of fig. 2. For clarity of illustration the first embodiment in fig. 1 is shown with the two walls or plate means somewhat removed from each other so that the various parts and components will be more easily visible. The figure shows a formwork system comprising first plasterboard elements 1 having groove and tongue profiles along the edges as shown at 11 and 12. At the groove and tongue profile 12 there is mounted a first spacer element 2 the main part of which has a shape conforming to the groove and tongue profile. A projecting part of the element 2 forms a hook or an eyelet 2A which projects into the casting space 4 between the two plate means which constitute the formwork.

A second plate means or wall plate in the formwork is formed by an exterior woodwool-cement plate 6 which on the inside is provided with an insulation layer 5. As an alternative the wall plate 6 can be made of sewage and/or industrial sludge with woodwool, lime and/or cement added, as already mentioned above. For co-operating with the first spacer elements 2 mentioned, there are provided second spacer elements 3 which with transverse members of H-shape are adapted to clamp the plate means 5, 6 upon mounting. The spacer elements 3 are mounted on the upper edge 13 of the plate means 5, 6 with the transverse members (the H- shape) projecting upwards and downwards respectively, so as to be in close contact with the inside and the outside

respectively of the plates 5, 6. Simultaneously coupling members 3A on the projecting end of the elements 3 are brought into engagement with corresponding coupling members 2A on the first spacer elements 2. Thereby the two wall parts are held in a fixed *mutual position and are intercon¬ nected so as to withstand the pressure when concrete is filled into the cavity 4 between the wall parts.

Before filling concrete into the cavity 4 it can be an advantage to arrange conduits and cables for electrical and sanitary installations respectively (hidden installation) .

It is a significant feature that the first plate elements 1 in the form of for example plasterboard, can be erected alone (but with spacer elements 2 inserted) , without any kind of strut or auxiliary devices. This means that this wall part will be sufficiently stable as a result of the groove and tongue profiles, the glueing and the thick¬ ness chosen, which results in a very efficient and a quick wall erection. With plasterboard elements of dimensions as mentioned above, it can be suitable in practice to have two or three spacer elements 2 along each horizontal joint.

As will be better seen from fig. 2 and in particular from fig. 3, the spacer elements for the plasterboard profiles can preferrably be formed of relatively thin, sheet-like strips shaped in compliance with the groove and tongue profiles. The second spacer elements 3 are suitably made of a wire or rod-like material and extend with their main parts more or less across the whole spacing between both wall parts, i.e. the cavity 4. This is the preferred arrangement, but embodiments may also be contemplated in which the first spacer elements are extended more or less into the casting cavity 4 in order to meet and be connected to the second spacer elements at a point in the cavity 4. However significant practical advantages are attained when the first spacer elements 2 are adapted to project very little into the casting cavity 4, whereas the second spacer elements 3 with their main part are adapted to extend over the major portion of the width of the casting space.

In the preferred embodiment of figs. 2 and 3 there is

shown as a component in the first plate means a plasterboard element 21. At the other side there .is shown a woodwool- cement plate 26 at the inside of which there is an insula¬ tion layer 25. Between the two wall parts there is estab¬ lished a casting cavity 24. First spacer element 22 which can be designed more in detail as shown in fig. 3, are adapted to co-operate with the profiles 32 on element 21. A projecting part 22B extends into the cavity 24 and is provided with a hole 22A so as to form a coupling member adapted to come into engagement with a coupling member in the form of a wire-shaped transverse member 23A on a spacer element 23 being attatched to the second plate means 26, 25. The main part of element 23 thus extends across the width of the cavity 24 and determines the mutual distance between the plate means 21 and 25/26. For anchoring the spacer elements 23 in wall plate 25/26 there are provided transverse members 23C and 23D which together with the main part of the element constitutes a substantially H-like shape. The distance between these transverse members 23C and 23D corresponds to the total thicknes of wall plate 25, 26. When mounting a further wall plate above the plate parts 25 and 26 shown, this will be held between the transverse members 23C and 23D projecting upwards, and the intermediate length of the main part 23B is clamped in the joint. This of course takes place after having put the transverse member 23A through the hole 22A. Thereby a stable and secure anchoring is obtain¬ ed, not only of both plate walls in relation to each other with a correct spacing, but also securing of plate parts 25 and 26 being mounted on top of each other, since the H-shape mentioned also will position such assembled plates more or less in a manner corresponding to the profiles with groove and tongue as described with respect to the plasterboard elements 21.

As seen from fig. 2 the three transverse members 23A, 23C and 23D lie substantially in the same plane and they all stand preferrably at a right angle from the main part 23B. When manufacturing these spacer elements from wire-shaped or rod-shaped material, a simple and efficient production is

obtained, which contributes to the total economy of the formwork system described here.

The fibres added to the plates described can be in the form of for example woodwool or woodchips, which means that where woodwool is mentioned herein, also woodchips can be employed and are usually preferred, such as in woodchip cement in the exterior wall plates.