The invention relates to a shuttering element to be repeatedly used for keeping poured concrete in the required shape until it is sufficiently hardened. It is generally known that for making a concrete construction, one needs shuttering. The shuttering forms an auxiliary construction that keeps the concrete cement in the required shape until it is sufficiently hardened. A shuttering has to meet a number of requirements. For instance, it has to be possible to work on and in the shuttering in order to provide iron reinforcement. The shuttering has to be sufficiently strong to bear the weight of the concrete cement. In addition, the sides of the shuttering have to be able to withstand the pressure of the not yet hardened concrete cement and the shuttering must not bulge or burst. Finally, the shuttering must not adhere to the concrete cement and it must be easy to remove the shuttering from the concrete, to unload or decentre without damaging the shuttering, the concrete or other building parts.

The use of, for instance, wood or a wood-like board material as shuttering material is generally known, while steel is also used. With smaller objects the shuttering is made on site by concrete joiners who are skilled in the art.

For the construction of houses in particular, but also for many other building projects, the shuttering is made from wood. Although basically wood can be reused sev¬ eral times for shutterings, much wooden shuttering material is still lost, for instance due to the panels needing to be sawn or otherwise machined. As a consequence the building trade annually requires very large quantities of wood for shutterings, which involves a considerable burden on the environment. In addition, the wood which cannot be used any more has to be destroyed as building waste, which not sel¬ dom causes pollution. It is the object of the invention to provide a shut¬ tering element of the kind described in the introduction,

exhibiting a favourable balance with respect to the envi¬ ronment. To this end the invention is characterized in that the element consists of form-retaining and impact-resistant polystyrene and is made from recycled plastic waste. It should be noted that board elements of this kind are already known and used as sheeting partitions. This application also has a favourable effect on the environment because it saves wood and waste plastics may be used with good results for this purpose. Surprisingly, recycled waste plastic is also exceedingly suitable as material for shut¬ tering elements in the building industry. Experiments have shown that there is no significant adherence of the con¬ crete cement to the material of the shuttering element. As a result of this finding it is for the first time that large quantities of shuttering elements from recycled plas¬ tic waste are used in the building industry with the double advantage for the environment that on the one hand less wood is required and on the other hand more plastic waste can be reused. The shuttering elements according to the invention are cheap, easy to machine with the customary tools, well suited for repeated use and may finally, at the end of a useful life span, be again recycled.

One embodiment of the invention is characterized in that the element comprises a substantially rectangular shuttering board having a concrete side facing the concrete to be poured and opposite to it, an outside. Such a shut¬ tering element replaces the in the building industry much used wooden boards. It is further possible to advantageous¬ ly use another embodiment which is characterized in that at its outside, the shuttering board is provided with a sup¬ port organ which is integrally formed with the board, for the support of a further shuttering element. The fact that the recycled plastic waste can be formed into any required shape by means of suitable machining methods such as extru- sion or compression, makes it possible for the first time to provide a shuttering board with support organs formed as a whole, for the support of further shuttering elements.

The invention also creates the possibility for another embodiment which is characterized in that the

element comprises a corner element consisting of two shut¬ tering boards joined together at an angle and formed as a whole. The invention makes it possible for the first time to produce shuttering elements consisting of shuttering boards which are joined, for instance, at right angles to form a whole. This allows an efficient assembly of corner constructions for shutterings.

Another embodiment of the invention is characterized in that the element consists of a girder placed at the out- side of the shuttering on the support organs of the shut¬ tering boards. This shuttering element according to the invention is particularly suitable for use in combination with the above-mentioned shuttering boards, so that the already mentioned advantages are further increased. The invention will now, exclusively by means of a non-limiting example, be further elucidated with reference to a schematic drawing of a few possible embodiments of the invention, in which:

Fig. 1 is a perspective view of the outside of a shuttering board, not facing the concrete to be poured,

Fig. 2 is a side view of a shuttering board of Fig. 2,

Fig. 3 is a perspective view of the concrete-facing side of a shuttering board according to Fig. 1, Fig. 4 is a continuous top view, partly in cross- section and, drawn at a distance from each other, parts of a number of shuttering boards according to Fig. 1 coupled to each other, as well as click pins used for this purpose, Fig. 5 is a perspective view of the outside of a shuttering element comprising two shuttering boards joined at an angle,

Fig. 6 is a top view of the shuttering element of Fig. 5,

Fig. 7 is a view of a shuttering element similar to that of Fig. 5, but now showing the side facing the con¬ crete,

Fig. 8 is a cross-section of a shuttering construc¬ tion using shuttering elements according to the invention, and in between the concrete cement, and

Fig. 9 shows a click pin of the kind illustrated in Fig. 4 on an enlarged scale and half of it in cross-sec¬ tion.

Identical parts in the different Figures are indi- cated by identical reference numbers.

Fig. 1 shows a shuttering element 1 for repeated use with shutterings intended for keeping the poured concrete in the required form. The element 1 consists of form-retai¬ ning and impact-resistant polystyrene and is manufactured in the known manner from recycled plastic waste. The element forms a substantially rectangular shuttering board having a concrete-facing side 2, see Fig. 3, and an oppo¬ site outside 3. The outside 3 is provided with two support organs 4 forming a whole with the board 1 for the support of a further, still to be discussed, shuttering element. To reinforce the shuttering board 1 an elongated flange 5 is provided at its top side as well as longitudinal ribs 6 and cross ribs 7. The flange forms not only a reinforcement but it also facilitates manipulation of the panels. Their dimensions are about 60 cm x 120 cm, while the mass is about 8 kg.

The panels can be connected longitudinally to form a roughly continuous elongated shuttering. To this end each separate shuttering board 1 is equipped with a few provi- sions. Near a side 8, the flange 5 is provided with a recess 9 located on the outside 3. At the side 10, the con¬ crete side 2 is provided with a recess 11. The side 10 is also provided with a wide reinforcement rib 12. As illus¬ trated in Fig. 3, the concrete side 2 of the shuttering board 1 is provided with a somewhat recessed part 13 oppo¬ site the reinforcement ribs 12. In this part 13 there are two centring pegs 14 forming a whole with the shuttering board, while near the side 8 corresponding slotting holes 15 are provided to admit, with clearance, centring pegs 14 of a adjacent shuttering board. At corresponding locations a number of passage openings 16 are provided near the sides 8 and 10.

Fig. 4 shows how, in accordance with Figs. 1-3, the shuttering panels can be connected to each other to form a

substantially continuous elongated shuttering. Fig. 4 shows portions of three shuttering boards 1, wherein the refer¬ ence numbers relating to the three separate shuttering boards are distinguished by the addition of an A, a B and a C respectively. To couple the shuttering boards they are placed next to each other such that the centring pegs 14 fall into the appropriate slotted holes 15 of the adjacent shuttering board. Then click pins 17, which are also made from recycled polypropylene and which can easily be fixed without any tools, are pressed through the passage openings 16.

The click pins 17, see also Fig. 9, comprise a stem 18 having a diameter slightly smaller than that of the pas¬ sage opening 16, so that the pins may be fitted into the opening without effort. A free end is provided with a tapering part 19 to facilitate the insertion of the click pens, while the other end is provided with a head 20 having a larger diameter than the stem 18. Inside the click pin is provided with a blind cylindrical cavity 21. The walls of the cylindrical part 18 are on both sides provided with recesses 22 having a hooked catch 23 forming a whole with the other part of the click pin and which is able to slightly move sideways with respect to an integrated hinge part 24 having a thickness which is somewhat less than that of the remaining wall portion of the stem 18. When fitting the click pin into the aligned openings 16 of two adjacent shuttering boards, see Fig. 4, the inner wall of the pass¬ age opening 16 pushes the catches 23 a little inward. The distance between the top of the catch 23 and the bottom of the head 20 is a little more than the sum of the thicknesses at that point of the two shuttering boards to be fastened to each other so that, after the entire click pin 17 has been pushed through the passage openings 16, the hooked catches 23 are again able to resiliently expand out- ward preventing the click pin from being retracted, so that it is secured in its position.

It is emphasized that apart from the support organs 4, the illustrated shuttering boards l and the click pin 17 are substantially the same as the sheeting partitions and

click pins already known from the state of the art. How¬ ever, the invention relates, as already stated, not first and foremost to a partition or board from recycled poly¬ styrene as such, but to the application of recycled poly- styrene in the manufacture of repeatedly usable shuttering elements for keeping poured concrete in the required shape.

Figs. 5, 6 and 7 relate to a novel corner element not known from the state of the art, wherein Figs. 5 and 6 relate to a so-called exterior angle element and Fig. 7 relates to an interior corner element. The exterior corner element is indicated with the general reference number 25 and the interior corner element with the general reference number 26. In view of the great similarity of these two elements to the shuttering board according to Figs. 1-3, these shuttering elements will only briefly be discussed. In the embodiment drawn, the corner elements do not possess any support organs corresponding with the support organs 4 of the shuttering board l. However, they may also be pro¬ vided on corner elements if so desired. The corner element 25 possesses two shuttering boards joined together at an angle, generally indicated with 25-1 and 25-2. In the embodiment drawn, these two shuttering elements stand at right angles to each other, e.g. the interior angle 27 is 90°. Such an element may be manufactured as standard element and may be used for on site construction of an exterior corner of a shuttering. The shuttering boards 26-1 and 26-2 which together form the corner element 26, also form an angle 27 of 90°. It differs from the corner element 25 in that the concrete is on the other side, so that this corner element is suitable for on site construction of an interior corner of a shuttering.

Finally, Fig. 8 shows the application of two shut¬ tering boards 1 for keeping in shape the concrete 28 poured in between. The shuttering boards are placed on a base 29 and fastened thereto to at the bottom of the shuttering boards 1 are so-called splash clamps 30. At that point these splash clamps absorb the lateral pressure which the poured concrete exerts on the shuttering boards 28. Accord¬ ing to the invention, a further shuttering element 30 is

placed in the support organs 4 at the outside of the shut¬ tering, which further shuttering element consists of a girder 31. Said girder consists of a prismatic beam of the drawn cross-section having any suitable length and is, just like the shuttering boards 1, manufactured from recycled impact resistant polystyrene plastic waste. In view of the elementary shape of such a beam, its cross-section is only indicated in Fig. 8 and is not further illustrated in the drawing. The top side of the thus formed shuttering is held together against the lateral pressure exerted by the con¬ crete cement 28 by means of a typical form brace 32 which is completely known in the art so that it will not be dis¬ cussed any further, except that the holding jaws are sup¬ ported by the girders 31. Although the invention has been elucidated above with reference to embodiments of only a few possible examples of shuttering elements which, in the drawn embodi¬ ments exhibit great similarity with already existing sheeting partitions, the person skilled in the art will, after reading the above description, be able to design other embodiments or adapted embodiments to suit the requi¬ rements. It is also possible to design and use completely different shuttering elements and the invention extends to any such shuttering elements intended to be repeatedly used for keeping the poured concrete in the required form, if said shuttering elements are manufactured in accordance with claim 1 and made from form-retaining and impact-resis¬ tant polystyrene produced from recycled plastic waste.