WO1998026138A1

WO1998026138A1 - Wall element for swimming pool with variable curvature

Info

Publication number: WO1998026138A1
Application number: PCT/FR1997/002028
Authority: WO
Inventors: Philippe Bach; Jocelyn Bourgeois
Original assignee: Procopi
Priority date: 1996-12-09
Filing date: 1997-11-12
Publication date: 1998-06-18
Also published as: AU5124498A; FR2756856A1; DE69722811D1; FR2756856B1; ATE242829T1; EP0943043B1; EP0943043A1

Abstract

This element, which serves as casing, consists of a caisson (1) in the form of a right-angled parallelepiped, for being vertically erected and attached to adjacent elements by its narrow lateral vertical edges; this element is characterised in that its external surface (14), initially plane, has vertical recesses (4) the width of which can be increased or, on the contrary, decreased, such that it is possible to give to the element (1) a concave or a convex curvature.

Description

VARIABLE CURVED WALL ELEMENT FOR POOL

The present invention relates to a wall element for the construction of a swimming pool, this element acting as formwork, intended to receive poured concrete.

It is therefore a so-called "lost" formwork, which remains in place once the concrete has set. The objective of the invention is to propose a wall element for swimming pools, the curvature of which can be modified at will, both to make it convex and concave, this in a relatively large range of radii of curvature, sufficient in any case in common applications.

Another object of the invention is to propose an element of the type mentioned, which is of a relatively low cost price, while being of a simple and easy-to-use design by the persons responsible for the construction of the swimming pool. .

The element proposed is initially planar, and therefore makes it possible to build conventional swimming pools, of polygonal outline, in particular rectangular.

However, at the time of installation, by bending the element, in one direction or the other, according to a determined radius of curvature, it is possible to construct swimming pools of various shapes, in particular swimming pools having an end portion of semicircular outline.

Document FR-A-2 637 933 discloses a stackable formwork block made of light material (expanded polystyrene for example), suitable for the manufacture of a swimming pool, the curvature of which is variable. It is a hollow block, which is indented on its external face. The opening thus formed is intended to receive a spacer. By playing on its width, you can bend the block, in one direction or the other, according to a variable radius of curvature. The spacer also prevents the escape of concrete when it is poured into the block. Such a solution is satisfactory for individual blocks, intended to be stacked one on top of the other in the manner of concrete blocks, in staggered staggered fashion.

It cannot be transposed to elements in the form of panels whose height corresponds to that of the swimming pool because the opening provided in the external wall of the element would not give this wall sufficient strength to retain the weight of the concrete. sunk over this entire height.

In addition, for straight blocks, it is either necessary to have specific blocks (without opening), or also to insert spacers therein.

In addition, said spacers must have the same height as the block to prevent the escape of concrete. The above-mentioned objectives are achieved, in accordance with the invention, thanks to the fact that the wall element consists of a box in the shape of a rectangular parallelepiped, intended to be erected vertically and adjoined to adjacent elements by its lateral vertical edges, characterized by the fact that its initially planar outer wall has vertical recesses formed by a folding of this wall, and the natural width of which can be increased or, on the contrary, reduced, so that it is possible to give the element a concave or convex curvature.

The external wall of the element is therefore not open. In addition, the wall fold delimiting the recess constitutes a reinforcing rib, so that the wall resists the weight of the poured concrete satisfactorily.

Furthermore, according to a certain number of additional, non-limiting characteristics of the invention:

- The element is compartmentalized by vertical transverse partitions, and includes a recess to the right of each compartment; - its internal wall is a double wall allowing good thermal insulation;

- its external wall is also a double wall, except opposite the recesses (good insulation);

- its side edges are double-walled; - Each of its side edges has complementary nesting members allowing its fixing by clipping against the edge of an adjacent element;

- the element is made of extruded plastic;

- Said recesses have a semi-cylindrical bottom, or approximately semi-cylindrical.

According to a first embodiment of the invention, the modification of the width of said vertical recesses is carried out by means of spacer members, adapted to increase this width, or by means of pliers, adapted, on the contrary, to reduce it. In this case, advantageously, the semi-cylindrical, or approximately semi-cylindrical, bottom of said recesses is bordered by a pair of grooves capable of receiving the spacer members.

Said spacer members are for example plates of generally rectangular shape, which ensure the spacing of the grooves by quarter-turn rotation, while said clamps have the approximate shape of a "C" and are put in place by translation, in vertical direction, inside the element, around the recesses. According to a possible characteristic of the element, its lateral vertical edges and - if necessary - its transverse vertical partitions have openings allowing the passage of poured concrete.

According to a second embodiment of the invention, the shaping of the element is ensured by means of a pair of horizontal bars capable of being fitted into its thickness, on the one hand at its base, on the other hand at its top.

The aforementioned openings which are at the base and at the top of the element are open, respectively downwards and upwards, constituting notches serving for the interlocking of said bars. The subject of the invention is also:

- A set of spacer members and clamps, of different dimensions, associated with an element, in accordance with the first embodiment;

- a shaping bar associated with an element, in accordance with the second embodiment. This element shaping bar advantageously has the following characteristics:

- Its ends have complementary male / female interlocking profiles allowing the end-to-end fixing of several bars;

- It has vertical openings intended to receive reinforcing bars for poured concrete;

- it is provided with lateral legs used to fix it to the ground;

- It is made of molded plastic, and it has two side walls defining an interior space open upwards and downwards, connected by reinforcing ribs; - one of these side walls has vertical slots which facilitate its bending.

The invention also relates to a set of spacer members and clamps, of different dimensions, associated with such an element.

Other characteristics and advantages of the invention will appear from the description and the appended drawings which present, by way of nonlimiting example, a possible embodiment. In the drawings:

- Figure 1 is a schematic top view of an element according to the invention; - Figure 2 is a schematic top view of a corner element capable of adapting to the element of Figure 1; - Figure 3 shows an element whose width is half that of Figure 1, this "half-element" being obtained by cutting the element of Figure 1;

- Figure 4 shows, on a larger scale, and in more detail, the lateral end portion of the element of Figure 1; - Figure 5 is also an enlarged view of the corner element of Figure 2;

- Figure 6 is a perspective view, with parts cut away from an end portion of an element;

- Figure 7 is a front view, external side, of the element of Figure 1 (on a smaller scale);

- Figures 8 and 9 are schematic views similar to those of Figure 1, which illustrate the method of bending the element, respectively using spacer elements (to make it concave), and using clamps (to make it convex), in a first embodiment of the invention. - Figures 10 and 11 are respectively front and top views of a spacer element;

- Figures 12 and 13 are respectively top and left views of a clamp;

- Figure 14 is a partial view, partly cut, similar to that of Figure 7, which shows a recess in the open state;

- Figure 15 shows, in cross section, a variant of the rear wall of the element, at a recess;

- Figure 16 is a schematic top view showing a part of the periphery of a swimming pool constructed using a number of elements according to the invention.

Figures 17 to 21 illustrate a second embodiment of the invention.

Figure 17 is a perspective view of a shaping bar, intended to be associated with an element according to the invention during the construction of the pool;

- Figure 18 is a top view of the bar of Figure 17;

- Figure 19 is a partial view, similar to Figure 18, illustrating the method of end-to-end assembly of two bars;

- Figure 20 is a top view similar to Figure 18, which shows a variant of the bar;

- Figures 20A and 20B are views similar to Figure 20, showing deformations by bending the bar, in different directions; FIG. 21 is an exploded view, diagrammatic and in perspective, illustrating the erection of a swimming pool wall using bars similar to those of FIGS. 18 or 20.

The element 1 illustrated in FIGS. 1 and 7 is a one-piece element, made of relatively rigid, but slightly flexible plastic material, for example PVC, obtained by extrusion.

The wall has a thickness of the order of 1.2 mm.

It is a hollow panel, in the shape of a rectangular parallelepiped box, of constant cross section, open at both ends. The open ends are the upper and lower ends when the panel is erected in a vertical position, in its normal position for the construction of a swimming pool.

This type of element is intended in particular for the construction of a buried, or semi-buried swimming pool, and the element serves as formwork receiving a concrete pour. It is a lost formwork, the formwork itself serving as a wall element once the concrete has set.

As an indication, the element has for example a length L of 500mm, a width 1 of 125mm.

Its height H corresponds to the height of the wall of the pool. This height is for example between 0.90 and 2.10 m. The height dimension is not critical for the manufacture of the element, since it is produced by extrusion, so that it is easy to cut it into sections of desired length, which will correspond to the height of the swimming pool.

This element has been designated by the reference 1, its internal wall, that is to say facing the interior of the future swimming pool, is referenced 10. For good thermal insulation, it is preferably a double partitioned wall, the internal side

(smooth) is referenced 100. It is against this face 100 that the sealing film - usually called "liner" - of the swimming pool will be applied.

The transverse end walls, or edges, of the element have been designated by the references 11 and 12. These are also double-walled (honeycomb structure), so that the element has good mechanical strength.

In the illustrated embodiment, the interior space of the box is compartmentalized by vertical transverse partitions, three in number, namely a central double-walled partition 13 and two simple intermediate partitions 15. These partitions very significantly improve the mechanical strength of the element, and prevent the deformation of the internal and external walls under the pressure of the mass of poured concrete. The outer wall 14 (single wall) has four folds which define as many vertical recesses 4, located to the right of the central part of each of the compartments, the interior space of which is referenced E.

As will be seen below, with particular reference to FIG. 4, the shape of these recesses, which are open towards the outside, allows a deformation of the wall, either in the direction of the reduction in width of the recess, or at otherwise in the direction of increasing its width.

The side walls 11, 12 of the element are provided with a set of elastic male / female latching members 2, 3. The male member 2 consists of a pair of tongues with non-return spouts, which extend vertically, parallel to the large direction of the element, while the female member is a vertical groove intended to receive said tongues 2.

The positions of elements 2 and 3 are reversed from one field to another, in such a way that it is possible to obtain the fixing by clipping of two adjacent elements, placed end to end.

In the example illustrated, the central partition 13 also has male 2 ′ and female 3 ′ elements similar to those of the end wall 11.

Thanks to this arrangement, it is easy to obtain a half-element, such as the element 1 'shown in FIG. 3, by simply cutting out an entire element at its central partition 13.

Figure 2 shows a corner element 5.

It is a vertical box, with a square outline, the interior space of which is referenced F.

This box has a double wall 50 on each of its faces, and has, on two adjacent faces, male / female clipping elements 2a, 3a on the one hand and 2b, 3b on the other hand.

This element 5 therefore allows the connection of two elements 1 perpendicular to each other, in a corner part of the pool.

Figure 4 shows in detail the configuration of a recess 4. It has a symmetrical shape, relative to a transverse plane. It comprises an entry bordered by two transverse faces 40, extending by transverse grooves 41, and an approximately semi-cylindrical bottom 42.

The bottom 42 is elastically deformable due to the flexibility of the wall 14. It should be noted that the recess 4 forms an integral part of the external wall 14, and each of the compartments E is therefore completely closed on all sides. It is open only at its upper and lower ends, to allow the passage of reinforcements and the pouring of concrete.

The views of FIGS. 4 and 5 also show the configuration of the male and female members 2, 3. It will be noted that the male part is carried by a projecting part 20 of the wall, which is centered in a complementary counterbore 30 bordering the opening at the time of clipping.

A similar configuration is provided on the corner element 5.

As can be seen in FIG. 6, the end edges (side walls) and the internal partitions of the element 1 are pierced by openings 16.

In the figure, only the edge 11 and a partition 15 are shown. Similar openings are made in the opposite edge and in the other internal partitions (not visible in the figure).

They advantageously have a circular shape, cut out with a hole saw. These openings 16 are arranged in a vertical line, at regular spacing.

As an indication, for a width of partitions of the order of 120 mm, their diameter and their spacing will both be of the order of 50 mm.

Similar openings are formed in the two walls 50 of the corner element 5, against which the elements 1 are applied.

The role of these openings is to let the poured concrete flow from one compartment to another (within the same element), and from one element to another. There is thus an invasion of all the elements by the concrete, and a global monolithic structure is obtained. Of course, the dimensioning and the positioning of the openings are the same for all the elements, so that the series of openings of an element comes opposite that of the adjacent element when two elements are joined and fixed the to each other by their end edges.

In a first possible embodiment of the invention, the element is bent by means of spacer elements or clamps.

Figures 10 and 11 show a spacer element.

It is a piece 6 of injected plastic, with high mechanical resistance, formed by a base 60 and a tenon 600.

The base 60 has an approximately rectangular general shape, its short sides 61 having a dimension B and its long sides 62 a dimension A greater than B. Two of its opposite angles are rounded to form cam surfaces 63.

The tenon 600, of square section, is perpendicular to the base 60, and is arranged in the center of the latter. A set of elements 6 of different dimensions is provided.

In this game, the odds B are always the same, but the odds A are different.

In practice, we will choose a dimension B slightly smaller than the value of the mutual spacing of the two recess entry edges 40 (see FIG. 4).

Thus, if these two parts are distant from 41mm, one will choose for example B = 40mm.

The value A will be greater than the value of the mutual spacing of the bottoms of grooves 41. Thus, if this value is 50mm, one can provide a set of four spacer elements having dimensions A of 56, 58, 60 and 62mm .

The clamp 7 - also made of injected plastic - illustrated in Figures 12 and 13 has the general shape of a "C" composed of a plate 70 and a pair of jaws 71. The clamp 7 is intended to come to the interior of space E; it is adapted to be put in place by translation from top to bottom around the recess 4, so that the jaws 71 are placed against the back of the entry edges 40 of the recess 4. As for the spacer members, it is provided a set of clamps 7, which have different dimensions C.

As an indication, if the mutual spacing of the portions 40 of the recess is 41mm, one could provide a set of four clamps 7, having dimensions C of 40, 39, 38 and 37mm respectively.

FIGS. 8 and 9 make it possible to understand how the positioning of the spacer elements 6 or of the clamps 7 makes it possible to carry out the bending of the element, so that its internal face 100 has a concave or, respectively convex, bending.

In one case, the action of the spacer element 6 has the effect of opening the semi-cylindrical part 42. The length of the external wall 14 is increased, which forces the element to bend as illustrated in the figure. 8.

In the other case, on the contrary, the clamp 7 has the effect of closing the part 42. The length of the wall 14 decreases, and the element bends in the opposite direction (FIG. 9). Each of the recesses 4 plays the role of a bellows which authorizes the deformation of the element.

The amplitude of this deformation, of course, is a function of the dimensions of the element 6 or 7 used. Of course, if no element 6 or 7 is used, the element retains its initial configuration, in the form of a flat panel.

For the same element, it is possible to use members 6 or 7 which do not have the same dimensions, in order to give it a progressive bending. For each of the recesses, a number of spacer elements or a number of clamps more or less important will be used, this depending on the height of the element.

For ordinary heights (about 1 meter), three elements will be used, for example, one in the upper part, the other in the central part and the third in the lower part.

This is what has been provided in the illustration of FIG. 14; this figure makes it possible to understand how the spacer members 6 are placed.

In this view, the lower and central members 6 are already in place. The upper element is presented in such a way that its large dimension is vertical, that is to say parallel to the grooves 41, the tenon 600 being turned outwards.

The member 6 is lowered by translation T into the recess.

This operation is easy because the dimension B mentioned above is smaller than the entry width of the recess. This is especially interesting for the establishment of the first member 6, which will "open" the recess. When it has reached the desired level, it is rotated a quarter of a turn, as symbolized by the arrow R. This operation can be done using a wrench that fits onto the square tenon 600. The zones curves 63 push the edges of the opening in the manner of cams, after which the member 6 is automatically retained by friction against the grooves 41.

The clamps 7 are put in place by simple axial translation inside the compartments.

Note that the jaws 71 have beveled edges which facilitate the adaptation of the clamps on the areas 40 of the recess at the time of this establishment.

In a variant of the system, the edges of the recesses and the clips are shaped in such a way that said clips can be placed not inside, but outside of the compartments (like the spacer members).

To build the pool wall, elements 1 are fixed next to each other, possibly bending them in one direction or the other, and according to the desired amplitude, as the contour is formed. of the swimming pool. It should be noted that, despite the bending, the lateral edges 11, 12 remain perpendicular to the internal walls 10 and external 14, so that the edges in contact with two neighboring blocks are applied perfectly against each other. This construction is done in a pit previously dug and provided with a concrete base provided with fittings or other protruding reinforcing elements, on which the elements are inserted during the operation.

In the corners, elements 5 are used. Where appropriate, half-elements 1 ′, curved or not, are also used.

Concrete is then poured inside all of the elements.

Concrete can flow from one compartment to another and from one element to the neighboring element, through the aforementioned openings 16. We therefore obtain a monolithic structure. The presence of the clamps 7 in the spaces E of the compartments absolutely does not contradict this operation.

Of course, the possible presence of organs 6 is not a problem either, since these organs are located outside the spaces E.

It is important to note that the wall recess 4, which forms an integral part of the external wall 14 of the element, constitutes not only a deformable part, allowing bending, but also a rib which considerably reinforces the external wall during casting. concrete.

After setting the concrete, the exterior space of the pool is filled with backfill. It then remains to carry out the finishing (installation of the "liner", the coping, etc.).

In the variant illustrated in FIG. 15, the external wall 14 is also (like the internal wall 10) a honeycomb wall - or double wall - formed of two "skins" 140-141 connected by a partition 142.

In this figure, the interior space E of the element is located on the left. This double wall is nevertheless interrupted at the level of the recess 4, only the internal skin 141 extending at this level to form the fold constituting the recess.

In this variant, the rigidity of the rear wall 14 is significantly increased. The fact that the recess is single wall is not a problem since - as already explained - this recess plays the role of a reinforcing rib.

In the illustration of FIG. 16, which shows a portion of the wall of a swimming pool thus constructed, there has been shown a corner element 5 which is connected on one side to an element 1A, and on the other side ( in a 90 ° direction) to a half-element 1 '.

The interior space of the swimming pool is designated El in the figure. The half-element 1 'is connected to two concave curved elements 1B, 1C. This same figure shows the concrete 101 poured inside the various elements, as well as the sealing film, which is applied against the internal face of the wall. This film, shown in broken lines, is referenced 102.

It is possible to produce elements in accordance with the invention at a reasonable cost, by the extrusion process, since a single die is sufficient to obtain an element which can have configurations of different shape.

This is also beneficial for storing items, since only one item template needs to be stored.

It is only necessary to provide sets of spacer members 6 or clamps 7 having different dimensions.

Since these parts are relatively inexpensive, the storage problem is not essential.

It goes without saying that the form of recess shown in the figures is only one possible example; other forms may be provided. In a second possible embodiment of the invention, illustrated by FIGS. 17 to 21, shaping members are associated with the wall elements 1.

In FIG. 21, the same references have been used to designate the different parts of this element, identical or similar to those illustrated in FIGS. 1 to 7. The bar 8 shown in FIGS. 17 and 18 is a single piece of plastic material injection molded. It is a part in the general shape of a rectangular parallelepiped, the longitudinal dimension of which is relatively large compared to the transverse dimension and to the height, which gives it the form of a "bar". This part is largely hollowed out, open upwards and downwards, its two parallel lateral partitions 80 being connected by ribs with vertical faces 82 arranged obliquely to form a zigzag partition. Certain ribs 82 carry vertical cylindrical sleeves 83 which constitute openings allowing the passage of reinforcing bars for the poured concrete. The ends 84 of the bar each have a set of male / female interlocking members, of the tenon 85 and mortise 86 type in dovetail, which allow several elements to be simply fixed end to end by interlocking from top to low. Such an assembly is illustrated in Figure 19, where two adjacent elements 8a, 8b are shown partially, after joining.

At the base of the bar are provided attachment tabs 81 having an opening 810 for the passage of a fixing member such as a screw. These legs are for example three in number, one placed in the central region of a side face 80, and the other two in the end regions of the opposite side face. Such a bar is intended to be associated with a wall element 1 such as that illustrated in FIG. 21 which, relative to the element previously described, has a particularity with regard to its openings 16 provided in its transverse partitions 15 and in its end edges 11, 12. This feature relates to the fact that the bottom openings 16 'and high 16 "affect the form of notches - or notches -, that is to say open downwards and towards the In the example illustrated, the openings 16 are in the form of elongated openings, of vertical longitudinal direction, with semi-cylindrical ends, and the upper and lower notches correspond to half-openings. has a length equal to that of element 1, for example 500 mm.

According to an important characteristic, its transverse dimensions are slightly smaller than those of the notches 16 ', 16 ", so that the bar can be embedded inside these notches, in the" thickness "of the element, without overflowing from it upwards or downwards. As an indication, the bar 8 has, for example, a height of 60 mm and a width of 40 mm.

As will now be explained, the bars 8 ensure the mounting and chaining of the elements 1 during the erection of the wall of the swimming pool as well as, if necessary, the shaping and the keeping in shape of said elements when 'they must be bent.

These bars therefore replace the spacer elements and / or the clamps of the first embodiment described. The deformable recesses 4, of variable width, can therefore be devoid of the ribs 41 which served to receive these members; they can have a simply semi-cylindrical wall 42. The bar of Figure 20, referenced 8 ', has the distinction of being able to be easily bent. For this, one 80 ′ of its side walls is not continuous. It is interrupted by vertical gaps 800 'of width i ₀ .

This discontinuity increases the deformability of the bar, which can easily be shaped by bending in a horizontal plane. FIGS. 20A and 20B represent deformations corresponding to a face 80 'made concave, with reduction of the gap width 800' (ii _< i ₀ ), and, respectively to a face 80 'made convex, with increase in width gap (i ₂ > i ₀ ) -

The ribs 82 can bend slightly to allow bending of the bar. Figure 21 illustrates the erection of a planar element during the construction of a swimming pool wall. We start by tracing on the ground, and more precisely on a concrete slab

D previously poured on the ground, the outline of the future swimming pool. The bars are then fixed to the ground, after having given them the appropriate configuration of curvature, and abutting them by fitting their male / female end members. This fixing is done using screws 811 passing through the fastening tabs 81, which are screwed into the slab.

A closed contour profile is thus produced on the ground on which all of the wall elements can be fitted.

Prior to this interlocking, holes are drilled in the slab D, using the sleeves 83 as a drilling template, for receiving the ends of reinforcing bars 9.

Then all the wall elements are fitted onto the series of bars, possibly by bending them, in one direction or the other, to adapt them to the conformation of the bars.

As illustrated in FIG. 21, each element 1 is advantageously offset, by half a length, relative to a bar. It is therefore placed "on horseback" on two adjacent bars.

However, such a shift is not compulsory.

The elements 1 fit from top to bottom on the bars 8 by their low notch 16 'which is fitted on the bar, while the peripheral edge of the element comes to rest on the slab D.

Thus the bars 8 are hidden and hidden in the thickness of the wall.

According to an important characteristic of the invention, each opening 83 is positioned in such a way that after fitting of the elements 1, it is located opposite a space E situated between two transverse partitions 11, 12, 15 (and not in look of such a partition).

Thus, it is possible to introduce from top to bottom inside these spaces E vertical bars 9, the end of which is inserted into the openings 83 and into the holes previously drilled in the slab. Horizontal fittings (not shown) can also be installed through the openings 16 to form, with the vertical bars, a solid frame intended to be embedded in the concrete.

Then place, end-to-end, a set of bars 8 (in the inverted position) in the upper notches 16 ". These bars are threaded through their openings 83 on the upper end portions of the irons 9, while giving them the same conformation (possible curvature) as the corresponding low bars. The entire wall is thus perfectly shaped, the series of bars 8 playing the role of chaining - or belts - peripheral high and low which stiffen the entire structure.

Concrete can then be poured into all of the elements. The presence of the bars does not interfere with this pouring since the bars are open upwards and downwards. The fluid concrete can flow between the spaces E, and from one element to the neighboring element, via the openings 16. It binds intimately to the ground thanks to the embedding of the wall on the low bars 8 which, remember the, are integral with the slab D, and also thanks to the presence of reinforcing bars which are driven into said slab. The presence of the high and low belts prevents any relative displacement of the elements 1 during filling.

Once the concrete has been poured and hardened, it suffices to cut off, if necessary, the projecting upper ends of the irons 9. The high bars 8 are embedded in the concrete and are invisible. The use of bars 8 (second embodiment) is not incompatible with that of spacer elements 6 and / or clamps 7 (first embodiment) which can be used additionally, in particular in the event of pronounced bending elements.

Rather than providing deformable bars, one could provide for different sets of bars, some straight, other curves but rigid, with a given radius of curvature.

Claims

1. Variable curvature wall element for swimming pools, which acts as formwork, characterized by the fact that it consists of a box (1) in the shape of a rectangular parallelepiped, intended to be erected vertically and joined to adjacent elements by its vertical edges side (11, 12), characterized in that its outer wall (14), initially planar, has vertical recesses (4) formed by a folding of said wall (14), and which it is possible to increase or reduce the natural width, so that it is possible to give the element (1) a concave or convex curvature.

2. Element according to claim 1, characterized in that it is compartmentalized by transverse vertical partitions (13, 15), and that it comprises a recess (4) in line with each compartment (E).

3. Element according to claim 1 or 2, characterized in that its internal wall (10) is a double wall.

4. Element according to one of claims 1 to 3, characterized in that its outer wall (14) is a double wall (140, 141), except vis-à-vis said recesses (4).

5. Element according to one of claims 1 to 4, characterized in that its lateral edges (11, 12) are double walled.

6. Element according to one of claims 1 to 5, characterized in that each of its lateral edges (11, 12) has complementary interlocking members (2, 3) allowing its fixing by clipping against the edge of an adjacent element.

7. Element according to one of claims 1 to 6, characterized in that it is made of extruded plastic.

8. Element according to one of Claims 1 to 7, characterized in that the said recesses (4) have a semi-cylindrical, or approximately semi-cylindrical, bottom (42).

9. Element according to one of claims 1 to 8, characterized in that the modification of the width of said vertical recesses (4) is carried out by means of spacer members (6), adapted to increase this width, or by means of pliers ( 7), adapted, on the contrary, to reduce it.

10. Element according to claims 8 and 9 taken in combination, characterized in that the semi-cylindrical, or approximately semi-cylindrical, bottom (42) of said recesses (4) is bordered by a pair of grooves (41) suitable for receive the spacer members (6).

1 1. Element according to claim 10, characterized in that said spacer members (6) are plates of generally rectangular shape, which ensure the spacing of the grooves (41) by quarter-turn rotation.

12. Element according to one of claims 9 to 11, characterized in that said clamps (7) have the approximate shape of a "C" and are put in place by translation, in vertical direction, inside of the element, around the recesses (4).

13. Element according to one of claims 1 to 12, characterized in that said lateral vertical edges (11, 12) and - if necessary - said vertical transverse partitions (13, 15) have openings (16) allowing the passage of poured concrete.

14. Element according to one of claims 1 to 8, characterized in that its shaping is ensured by means of a pair of horizontal bars (8) capable of being fitted into its thickness, on the one hand at its base, on the other hand at its upper part.

15. Element according to claims 13 and 14 taken in combination, characterized in that the openings (16 ', 16 ") which are at its base and at its upper part are open, respectively downwards and upwards, constituting notches used for fitting said bars (8).

16. Set of spacer members (6) and clamps (7), of different dimensions, associated with an element according to one of claims 9 to 13.

1 7. Shaping bar (8) associated with an element according to claim 14 or 15.

18. Bar according to claim 17, characterized in that its ends (84) have complementary male / female interlocking profiles (85, 86) allowing the end-to-end fixing of several bars (8).

19. Bar according to claim 17 or 18, characterized in that it comprises vertical openings (83) intended to receive reinforcing bars (9) for the poured concrete.

20. Bar according to one of claims 17 to 19, characterized in that it is provided with lateral tabs (81) serving to fix it to the ground.

21. Bar according to one of claims 17 to 20, characterized in that it is made of molded plastic, and that it comprises two side walls (80) defining an interior space open upwards and downwards and which are connected by reinforcing ribs (82).

22. Bar according to claim 21, characterized in that one

(80 ') of said walls has vertical slots (800') which facilitate its bending.