Panel for poured concrete retaining walls of concrete forms , particularly for concrete slab forms or the like and process of making such panel

The invention relates to a panel for poured concrete retaining walls of concrete forms , particularly for concrete slab forms or the like, which panel is comprised of at least one bearing layer of wood or the like, which is at least partly externally covered with one or more moisture and/or water sealing and/or protecting layers . Poured concrete forms are well-known, and are composed of a plurality of panels which jointly act as concrete retaining walls for imparting the desired shape and size to concrete and which panels are mounted in such arrangement as to form said retaining walls in a load-bearing structure.

As mentioned above, each panel is comprised of at least one bearing layer of wood having such length, width and thickness dimensions as to withstand concrete stresses without deforming, while ensuring easy handling thereof by the operators that carry and mount the form. Such dimensions, especially the thickness, are substantially fixed. Hence, there currently exists the problem of increasing the load resistance of panels without changing their thickness and particularly without increasing their thickness.

It is further known to make panels of the above type, in which the wood layer is protected, at least along some of its side edges and/or portions of some

side edges, and along at least part of at least one of the two faces , by one covering layer of an impermeable material, such as resins, films or layers of plastic materials or the like. It is finally known to make the wood part in the form of two or more layers, wherein the strips of one layer and those of the adjacent layer are in crossing relationship and/or in the form of superposed sheets of wood glued together, in crossing relationship regarding the orientation of the wood fibers of each layer, such as plywood sheets .

Other known arrangements include a layer of wood fibers or the like, consisting of particles and/or dusts pressed and stuck together using resins or glues, such as the so-called particleboards or the like.

Particularly concerning the making of walls of slab forms , the panels have to exhibit a sufficient bending strength under the weight of concrete. Wooden strips have a higher strength in the longitudinal direction of wood fibers than in the transverse direction.

Therefore, the strips are formed with their longitudinal axis oriented in the same direction as the wood fibers, as indicated by the natural grain of wood, whereas the transverse end edges of the strips extend transverse to wood fiber orientation.

Therefore, a panel having improved bending strength shall be formed of a plurality of adjacent strips disposed on at least one layer, i.e. coplanar and oriented with their longitudinal axes parallel to the wood fibers and parallel to the longitudinal direction of the panel, the adjacent strips being in side-by-side positions and joined together by chemico-

physical bonding or gluing at the mutually contacting longitudinal edges .

Nevertheless, the end edges of these panels are oriented transverse to the orientation of the wood fibers and are particularly water and/or moisture permeable .

Furthermore, such end edges, as well as the corner areas that they form with the corresponding longitudinal edges are exposed to mechanical actions which might cause damages to the panel, thereby causing panel deformations and/or affecting moisture protection, which might accelerate moisture-induced wood deterioration.

The invention has the object of providing a panel as described hereinabove which, using simple and inexpensive arrangements, can exhibit a resistance to stresses acting on the panel better than or at least identical to that of the existing panels, while effectively obviating the drawbacks of existing panels, i.e. affording effective protection of the panel against both mechanical damages and vulnerability of the seal to water or moisture, without affecting and, conversely, increasing load resistance of the panel and without requiring any thickness increase or any complex and extensive changes to the structure and materials of the panel .

The invention fulfils the above objects by providing a panel as described hereinbefore, i.e. a panel for poured concrete retaining walls of concrete forms , particularly for concrete slab forms or the like, which panel is comprised of at least one bearing layer of wood or the like, and wherein at least one edge of the panel is oriented, at least over a portion

thereof, transverse to the direction of the wood fibers and has a sealing edge at least over said portion, which is made of plastic, overlies the end side of said panel at least along said portion of said edge, and is fixed to said end side of the panel by physico-chemical bonding thereby sealing it from the environment.

According to one embodiment of the invention, the panel has a bearing layer, particularly of wood or another similar material, such as a so-called particleboard or similar materials formed of wood particles or natural fibers compacted together and bonded with appropriate adhesives and/or resins , which bearing layer is covered, on one or both faces, by a layer of protective and particularly sealing material , a channel or groove being provided at least along a portion of the panel sides having the sealing edge, which groove extends directly underneath the side of the protective layer/s adhering to the bearing layer of the panel and which groove is delimited at least on one side by said side of the corresponding protective layer, whereas the sealing edge also extends into said groove and also sticks by chemico-physical bonding to the bottom and sidewalls of the groove.

In one embodiment, the groove extends throughout the entire thickness of the bearing layer and is delimited on two sides by the two opposed protective layers, the end side of the bearing layer being recessed relative to the end sides of the two protective layers . In a further variant embodiment, the groove has a thickness that corresponds to a part of the thickness of the bearing layer and is laterally delimited on one side by the corresponding protective layer and on the

other side by the surface parallel to the protective layer of a stepped recess which is formed along the corner area of the bearing layer side which directly underlies the protective layer, whereas the bottom of said groove is formed of the step of such stepped recess in the bearing layer.

Essentially, the protective layer externally covers the stepped recess, while leaving a peripheral band exposed, corresponding to the depth of the milling or the depth of the stepped recess which is exposed or accessible from the groove.

However, the sealing edge has a groove filling extension and sticks by chemico-physical bonding to the groove walls formed of the materials of the bearing layer and the protective layer.

According to one improvement, when the bearing layer is covered with a protective layer on each of the two opposite faces , then a groove of the above type is provided, having a partial thickness relative to the entire thickness of the bearing layer directly underneath each of the two protective layers and along the sides having the sealing edge, such sealing edge having thus groove filling extensions for each of said two grooves, which extensions stick by chemico-physical bonding to the materials of the groove delimiting walls .

In a further improvement, the protective layer/s are formed of plastic and the sealing edge sticks in a watertight manner to the end side of said protective layer/s and to the side of said protective layer/s which forms the side wall of the corresponding groove.

By this arrangement, an adhesive band is simply created for bonding the plastic material of the sealing

edge to the plastic material of the protective layer/s, which extends beyond the simple thickness of said layers. Thus, the penetration path of moisture or water into the bearing layer of wood or the like is longer and extends from the outer side of the junction between the sealing edge and the protective layer to the bottom of the groove through a length corresponding to the depth of said groove .

Still according to a further advantageous improvement, the sealing edge is made by injection molding, wherefore the groove filling extensions are absolutely non problematic .

According to a further feature, the panel has a bearing layer between two protective layers which adhere to one face of the bearing layer respectively, the bearing layer having a tongue in a central position with respect to the overall thickness of the bearing layer, which has a smaller thickness than the overall thickness of the bearing layer, which tongue protrudes out of the corresponding peripheral side of the protective layer/s and which tongue is embedded in the sealing edge which covers it along the sides parallel to the panel faces and the end side, thereby complementing the thickness of the panel to the overall thickness of the protective layers and the bearing layer .

According to an improvement, when the panel has a channel or groove directly underlying each of the protective layers , which channels or grooves are formed of peripheral stepped recesses of the bearing layer, said tongue is a peripheral extension of the part of the bearing layer that is interposed between the two stepped recesses, wherefore the surfaces of said tongue

parallel to the panel faces extend flush with the corresponding surfaces of the stepped recesses that form said channels or grooves .

In a further advantageous feature, holes or apertures are provided in said tongues, which extend throughout the thickness of said tongues, whereas the sealing edge penetrates therethrough with bridges of material which connect the two layers of material of said edge that cover the two faces of said tongues parallel to the faces of the panel .

This construction provides both chemico-physical and mechanical connection between the sealing edge and the material of the protective layer. The transverse bridges of sealing edge which fill the through holes form some kind of mechanical retaining nails that assist the mechanical connection between the bearing layer and the sealing edge. This is synergistically reflected on the connection between the sealing edge and the protective layers, thereby forming a watertight junction. Thus, the mechanical connection of the sealing edge to the bearing layer prevents any displacement of this edge relative to the layer and, as a result, any tears or cracks in the junction between the sealing edge and the material of the protective layers .

Still according to a further improvement, the stepped recess that forms the grooves allowing the sealing edge to penetrate beneath the protective layer/s has a bottom or riser surface with a concave shape. This optimizes absorption of thrusts during injection of the sealing edge material, and prevents high injection pressures from causing the protective edge/s to be lifted.

According to yet another variant, a fiber layer may be provided between the protective layer/s and the bearing layer. Here, such fiber layer may also extend into the corresponding channel or groove, whereby the sealing edge material would stick to the protective layer in an indirect manner, with said fiber layer being interposed between such sealing edge material and the protective layer.

In a further advantageous improvement, the sealing edge also has reinforced inserts for connection of panel lifting or dismantling tools , such as levers , crowbars or the like .

In one embodiment, rigid inserts, possibly having apertures and indentations for engagement of said lifting tools are incorporated in the sealing edge by being embedded therein.

However, in a variant embodiment, the connection inserts are formed of thicker areas of the sealing edge, when compared with its thickness parallel to the panel faces. This is obtained by providing one or more recesses in the end sides of the panel having the sealing edge, wherefore a greater thickness of material is provided at said recesses, as compared with the peripheral end edge of the finished sealing edge. While the sealing edge may be provided along all the sides or along any sides whatever of the panel, in a preferred embodiment sealing edges may be provided along the end sides of the panel .

As better explained hereafter, these end sides are oriented transverse to the direction of the wood fibers through at least a part or the whole of the thickness of the bearing layer.

In a particular case, the bearing layer is

composed of a plurality of parallel strips disposed on one, two or more layers and the strips of these layers have the wood fibers all oriented in the longitudinal direction of the strips, and in substantially identical and/or parallel directions for the strips of all the layers . Here , the fibers are oriented transverse or perpendicular to the end sides of the bearing layer throughout the entire thickness, i.e. the entire surface of the end side. When the edge of the wood layer with the sealing edge thereon is oriented transverse to the wood fibers, like in the above case, the surface along said edge has a rough or anyway porous and irregular texture, which improves mutual penetration of said wood surface and the plastic material of the sealing edge, thereby strengthening both the mechanical connection therebetween and the sealing effect, by generating a moisture barrier having a certain penetration depth into the wood layer. Alternatively to the above, the bearing layer may be composed of two, three or more layers of wood strips, which strips have identical orientations of the wood fibers and/or the longitudinal axis of the strips in a first part of the layers, whereas at least one second part of the layers has the strips with identical orientations of the wood fibers and/or the longitudinal axis of the strips within such second part of layers and with crossed, transverse or perpendicular orientations with respect to that of the strips of said first part and/or further parts or subsets of layers of strips that form the bearing layer. In this case, the layers of strips of said first part of layers and the layers of strips of said second part and/or further

parts of layers are disposed in alternating orders, with a layer of a second part interposed between two layers of said first part of layers.

Therefore, in this case the end sides of the bearing layer will be oriented transverse to the wood fibers and/or the longitudinal extension of the strips for certain layers of strips only and for a portion of the surface of the end side.

Additionally, the panel may have one or more outer protective layers on one or both faces , having a moisture barrier function as well as a concrete adhesion preventing function.

These protective layers may be formed of thin films of resins, varnishes or the like, or plastic layers, such as layers formed of vegetable flour-filled polypropylene, e.g. the one known under the name of Woodstock®. These protective layers may be joined in a watertight manner by chemico-physical bonding to the sealing edges, thereby forming a plastic or resin skin for sealing the inner wood layer, which is tightly closed on all layers by such chemico-physical bonding, such as by sealing, gluing or the like.

In the above examples, the sealing edge is applied on the panel that already has the wood layer and a covering or protective layer on at least one side, so that, during molding, the sealing edge material overlies the end surface of the wood panel edge and the corresponding thickness of the edge of the covering and/or protective layer. Particularly referring to the case in which at least one additional layer of side-by-side wood strips, joined together along the mutually contacting longitudinal sides of the longitudinal edges of such

strips, may be fixed over the first layer of strips, directly or with the interposition of additional layers of wood fibers of different types and structures from the ones described above, it was found to be highly advantageous to provide at least two superposed layers of wood, each composed of a plurality of side-by-side strips of wood joined together along the mutually contacting longitudinal sides of the longitudinal edges of such strips, the wood fibers of each strip being oriented in the longitudinal direction of the strips.

Advantageously, in this configuration the position of the strips of a first layer is transversely offset from the position of the strips of at least one second adjacent layer so that the mutually contacting and joined longitudinal surfaces of the strips of said first layer are in positions of non-coincidence with the mutually contacting and joined longitudinal surfaces of the strips of the second layer, i.e. in a position of coincidence with a longitudinal intermediate axis of the strips of the second adjacent layer and obviously vice versa.

This configuration has considerable advantages . From a mechanical point of view, the panel exhibits an improved load resistance with reference to its extension parallel to the longitudinal extension of the strips. This longitudinal direction is essentially parallel to the orientation of the wood fibers and thus to the condition in which the wood material has its highest mechanical load resistance. The at least two wood layers, each composed of a set of adjacent strips joined together, which strips are oriented with parallel longitudinal axes and which longitudinal axes are essentially parallel to the orientation of the wood

fibers ensure an increase of the load resistance with respect to said longitudinal direction of the panel . Such increase is obtained by having one wood layer of the panel composed of two layers of strips, which has a higher load resistance as compared with the resistance provided by a conventional panel having one wood layer composed of at least three superposed layers of strips and in which the strips are in mutual crossing relationship. The advantages of this configuration are well beyond those mentioned above because, as the strips of the layers are parallel, with respect to both the direction of the longitudinal axis and the direction of the wood fibers , the surfaces of the end edges of the strips oriented transverse to the wood fibers are provided only along the two transverse edges of the panel .

Furthermore, considering that the surfaces of a strip that are oriented parallel to the wood fibers have a negligible water or moisture absorption, then moisture and/or water sealing is only required along said two edges of the panel that have or are formed by the end sides of the strips.

As mentioned above, an alternative embodiment may be provided in which the bearing layer of wood is composed of a plurality of superposed layers of strips, in which successive layers have strips alternately oriented in two different directions, i.e. with a crossed or preferably perpendicular orientation with respect to the orientation of the wood fibers and/or to the longitudinal axis of the strips. In a specific configuration, two layers of strips are provided, in which the strips are oriented parallel to each other

with reference to the direction of the wood fibers and/or their longitudinal axis and have one or more layers, preferably one layer of strips interposed therebetween, in which the strips are oriented with the wood fibers and/or their longitudinal axis crossing, i.e. transverse or preferably perpendicular to the direction of the wood fibers and/or the longitudinal axis of said first two layers.

In this configuration, only the two layers of strips on the two faces of the bearing layer have wood fibers oriented transverse or perpendicular to the end sides of the panel, whereas the wood fibers of the intermediate layers are oriented parallel to the end sides and perpendicular or transverse to the longitudinal sides of the bearing layer.

While the panel with this configuration suffers from the drawback of a greater moisture absorption by the intermediate layers , as no panel protection is provided along the longitudinal edges and the wood fibers of the intermediate layers are perpendicular to the longitudinal sides of the panel, there is only one layer in which the panel has a high porosity along the longitudinal sides and moisture absorption, if any, causes at the worst a substantially homogeneous thickness increase in the panel, with no peeling off or delamination of the layers that form the panel and/or no localized swelling that would give the panel an irregular shape .

A mechanical advantage is also achieved, which obviously consists in an increased transverse rigidity of the panel, and another advantage is that, if the panel faces are perforated by nails or screws , the panel has a surprising behavior as regards the

deformation effects generated by moisture penetration in the bearing layer through such holes , i.e. swelling effects that are less localized around the hole and rather distributed on a wider surface area, with a lower deformation rate and an overall lower thickness increase . Thus the surface of the panel maintains a substantially homogeneous appearance, whereas peeling off of the outer protective layer around the hole, which is usually associated to very localized and raised swelling is considerably limited or avoided.

According to yet another advantageous feature of the present invention, which may be provided individually or in combination with the previous features, the wood layer has recessed corner areas that are filled with plastic inserts having such a shape as to complement the peripheral shape of the panel to obtain the ideal shape that might be envisaged without such recessed areas.

The recesses at the corner areas of square, rectangular or polygonal panels are curved chamfers of the corner areas which also partly extend along the initial sections of the longitudinal sides of the panel and are filled with the sealing edge material for complementing the shape of the panel to the envisaged final rectangular, polygonal or square shape. Therefore, the sealing edge also extends along the chamfered corner areas of the panel and along the initial sections of the two longitudinal edges directly adjacent to said corner areas. Advantageously, both the groove/s underneath the protective layer/s and the tongue of the protective layer, if any, with or without through holes also extend along such chamfered corner areas and along the

initial recessed section of the longitudinal sides of the panel directly adjacent such corner areas.

This arrangement provides an effective shock protection at the corner areas of the panel, which are particularly exposed to damaging during transportation, assembly and/or dismantling of the form.

The invention relates to further characteristics which form the subject of the dependent claims.

The characteristics of the invention and the advantages derived therefrom will appear more clearly from the following description of a non-limiting embodiment, illustrated in the annexed drawings, in which :

Fig. 1 is a schematic plan view of a first embodiment of the panel of the present invention, with the protective layer being removed in a median area, and the sealing edge being only provided along the end sides transverse to the wood fibers and around the corner areas , as well as at the initial sections of the longitudinal sides adjacent to such corner areas.

Fig. 2 is a perspective view of a bearing layer composed of two layers of wood strips disposed with their longitudinal axes and/or wood fibers oriented parallel to each other and parallel to the longitudinal direction of the strips.

Fig. 3 is a cross section of a panel with an intermediate bearing layer composed of two layers of strips and with two protective layers, each overlying one of the faces of the bearing layer respectively. Fig. 4 shows a panel with an intermediate bearing layer composed of a single layer of strips and with two protective layers, each overlying one of the faces of the bearing layer respectively.

Figs. 5 to 10 show enlarged details of cross sections of an end side of the panel with a sealing edge thereat, in different variant embodiments of the invention . Fig. 11 is a plan view of the transverse end edge of the panel of Figs . 1 and 5 which shows the peripheral tongue of the bearing layer protruding beyond the peripheral edge of the protective layer and the through holes in said tongue, the sealing edge being indicated by dashed lines .

Fig. 12 shows a variant embodiment of the panel of Fig. 8 in which the outline of the peripheral edge of the bearing layer and the protective layers has recesses adapted for use as connection areas for panel dismantling tools .

Fig. 13 shows a detail of one end side of the panel having a sealing edge in which connection inserts for panel dismantling tools are incorporated by being embedded therein. Fig. 14 is a perspective view of a panel as shown in Fig. 13 with said tool connection inserts being embedded in its sealing edge, which inserts have tool engagement cavities that are open at the end side of the sealing edge . Referring to Fig. 1, there is shown a panel, particularly for slab forms or the like, according to the invention .

It has to be noted that the examples of this description shall be intended without limitation and that they only represent some of the selectable variant embodiments , in which the configuration of the panel is a preferred configuration or a configuration which best illustrates the inventive teaching.

As a rule, formwork panels are about one to three meters long and about 0.5 to 1.5 meters wide , length being greater than width (thereby forming a rectangular shape) and have a thickness that changes, depending on their materials and structure, from a few centimeters to about ten centimeters . These maximum and minimum sizes change depending on the configuration of the bearing frame in which the panels are mounted in side- by-side positions for forming the retaining walls of forms .

The thickness of the panels may fall in a range of thicknesses from about one or a few decimeters to about one or a few centimeters .

Referring now to Fig. 1, there is shown a panel according to a first embodiment of the invention in which the panel has a basic configuration as regards the number of layers and the number of parts .

In this embodiment, the panel is comprised of at least one bearing layer of wood 1, which is covered on both faces by a protective and/or waterproofing layer 2 and further has, along at least the two opposite sides transverse to the longitudinal axis of the panel and/or to the orientation of the wood fibers of the bearing layer 1 , a sealing edge 4 which adheres by chemico- physical bonding to the bearing layer 1 and to the protective layers 2, while wrapping in a moisture- and/or watertight manner the corresponding end side of the bearing layer of the panel.

The sealing edges 4 extend to the corner areas of the assembly composed of the intermediate bearing layer 1 and the two opposite protective layers 2 and to a certain length along the two longitudinal sides of the panel by two extensions 104.

The covering and protective layers 2 may be formed of varnish or resin films or plastic layers in the form of sheets applied by gluing or other types of bonding or fixation to the wood layer. Particularly, the covering and protective layers 2 may be formed of vegetable flour-filled polypropylene sheets, such as sheets of a material known under the tradename Woodstock® .

The covering and protective layers 2 of the intermediate bearing layer 1 may be also composed of multiple layers of materials joined together and attached to the faces of the intermediate bearing layer 1 which, as mentioned above, may be also formed of multiple layers. The thickness of the cover and/or protective layers 2 falls, for instance, within a range from a few tenths of a millimeter to a few millimeters and may even fall below or above such values , depending on the type of the cover layer among those listed above . If the protective and/or cover layer is formed of inert-filled polypropylene sheets or the like, the thickness of such layers is from a few tenths of a millimeter to a few millimeters .

The covering and protective layers 2 may be attached to the bearing layer 1 once that each of them has been formed by joining together further layers or all the layers that form the panel .

In these cases , the covering and protective layer/s 2 are attached before application of the sealing edge/s 4 so that, upon application of these sealing edges 4 , these sealing edges 4 overlie the end sides of the edges of the covering and protective layers 2 and are connected therewith to form a

watertight junction. Therefore, the covering and protective layers 2 stick in a watertight manner to the sealing edges 4 by chemico-physical bonding between the plastic materials that form such parts. Various methods may be used to apply the sealing edges. A particular advantageous method is injection molding of the sealing edge material onto the corresponding end side of the assembly composed of the bearing layer 1 and the protective and/or cover layer/s applied thereon.

As shown in Fig. 2, the wood layer may be composed of two or more superposed wood layers IA, IB. Each of these layers may have a different structure. One of the layers or some of the layers or all of the layers may be formed of wood sheets, like in plywood. One, some or all of the layers may be formed of particleboards or the like. One of the layers or at least some of them or all of the wood layers may be composed of a plurality of strips in side-by-side relationship to form a continuous layer. The wood strips may extend continuously all along the wood layer or may be shorter than the wood layer IA, IB, the wood strips being side- by-side both laterally and longitudinally.

While the sealing edges 4 and the stiffening strips 3 may be provided along each peripheral edge of the wood layer with or without the covering and protective layers 5, the invention contemplates a further improvement which helps to increase the load resistance of the panel at least in one direction of extension thereof without requiring any increase of the thickness or weight of the panel and also avoids the need to cover the edges of the wood layers along all their sides .

Referring to Fig. 3, there is shown a wood layer 1 composed of two layers IA and IB of superposed wood strips. As shown in Fig. 3, the wood strips 3 of each layer are arranged with parallel longitudinal axes , unlike the prior art configuration. Each layer of strips IA, IB is composed of laterally contiguous strips, which are joined together by chemico-physical bonding at mutually contacting side surfaces. When the length of the strips corresponds to the dimension of the wood layer in this direction of the strips, then there are no contiguous strips in the longitudinal direction. Otherwise, the strips are also longitudinally contiguous, with the end contact surfaces transverse to their longitudinal axis offset from the end contact surfaces of two successive strips laterally adjacent threto.

Furthermore, the two layers of wood strips are disposed in superposed relationship, with the mutually contacting longitudinal side surfaces 103 of the strips of one layer laterally offset from and coincident with an intermediate longitudinal axis of the strips of the adjacent layer IB of wood strips.

The layers IA and IB of wood strips, as well as the wood strips 3 themselves are glued together in a manner known to those of ordinary skill in the art.

According to an advantageous feature, the strips are formed with their longitudinal axes oriented in the direction of the fibers and the grain of wood. Thanks to this feature, each strip and the whole panel has an improved load resistance in the longitudinal extension of the strips and the panel, because wood has a higher resistance to stresses in the direction of the fibers and grain.

In a further feature of this configuration, at least the longitudinal edges of the wood layer 1 can be free of any cover, as moisture absorption or penetration through the surfaces of the strips oriented parallel to the wood fibers and grain is considerably lower than moisture absorption and penetration through the surfaces oriented transverse to the direction of the wood fibers .

Thus, the wood layer edges oriented transversely, i.e. in the panel width direction, consist of the end sides of the strips, which are oriented transversely to the wood fibers and grain.

The sealing edge 4 is applied to such transverse edges of the wood panel . The latter are constructed as described above. By applying of the sealing edge 4 , particularly by overmolding, to the end sides of the strips oriented transverse to the wood fibers, the plastic material of the sealing edges 4 , due to the higher porosity of these surfaces, to penetrate to a certain extent into the pores and between the wood fibers, thereby causing an effective sealing action against moisture penetration, as well as a better attachment of the sealing edge 4 to the surface of the wood layer edge that generates, in addition to the intrinsic chemico- physical bonding of the plastic material, a mechanical bonding action caused by mutual penetration of such plastic material and the wood fibers.

As mentioned above with reference to Figs . 2 and 3, the wood layer 1 or the superposed layers IA and IB may have their outward faces covered by a cover and/or protective layer 2. The covering and protective layer/s 2 are formed of varnish, resin or plastic films or

sheets, which are joined by chemico-physical bonding to the wood layer/s, whereas the sealing edge 4 also overlies the end surface of the edge of said covering and protective layers 2 at the edge of the wood layer/s 1, IA, IB with said covering and protective layers 5 attached thereto, said sealing edge 4 being connected in a watertight manner to the corresponding edge of said covering and protective layers 5 by chemico- physical bonding. Obviously, a sealing edge may be also provided at the longitudinal edges of the wood layer/s 1, IA, IB.

Fig. 4 shows, like Fig. 3, a variant embodiment in which the bearing layer of wood 1 is formed of a single layer of parallel contiguous strips, which are formed with their longitudinal axis oriented substantially parallel to the wood grain and/or fibers , like in the previous examples. Once again, both opposite faces of the bearing layer 1 are covered by a protective and/or covering layer 2. For an even more reliable watertight junction between the sealing edge 4 and the protective and covering layers 2 of the panel against moisture or water infiltration, the invention provides a larger mutually contacting and watertight chemico-physical bonding surface between the sealing edge 4 and the protective and/or covering layers 2 along the part that has such sealing edge extending thereon, and in the water penetration and infiltration direction from the outside to the inside of the panel through the junction between the sealing edge and the protective and/or covering layers 2.

According to a first embodiment, as shown in Fig. 5, along the contact end side between the sealing edge

4 and the panel , the intermediate bearing layer 1 terminates in a recessed position to a predetermined length with respect to the corresponding edge of the covering and/or protective layer/s 2. This creates a peripheral channel whose bottom is formed by the end side 101 of the intermediate bearing layer 1 of wood or the like and whose delimiting side walls are formed by the peripheral bands 102 of the protective layers 2 that protrude outwards beyond the end side 101 of the intermediate bearing layer 1.

Therefore, the sealing edge 4 has a extension or rear tongue 204 whereby it engages in this peripheral groove of the panel thereby entirely filling its cavity and sticking by chemico-physical bonding to the end side 101 of the bearing layer 1 and to the free surface of the protective layers 2 which faces towards the intermediate bearing layer 1 and extends along the protruding peripheral bands 102 of the layers 2. The adhesion against the bands 102 of the layers 2 creates a water- and moisture-tight attachment extending through the thickness of each protective or covering layer 2 and the width of the peripheral band 102 that forms the side wall of the peripheral groove of the panel which is filled by the rear tongue 204 of the sealing edge 4. Thus , a watertight attachment area between the protective or covering layers 2 and the sealing edge 4 which is very large in the direction of the water penetration path with reference to the thickness of these protective layers 2. In the variant of Fig. 6, the end side of the bearing layer 1 is shaped in such a manner as to have two separate grooves instead of one groove, each extending level with the contact surface of one of the

faces of the intermediate bearing layer with its respective protective layer 2 and along the area of the corresponding edge of the end side of such bearing layer 1. Particularly, each of the two grooves is formed by a stepped recess formed along the area of the corresponding end corner of the intermediate bearing layer, whereby the groove leaves the face of the corresponding protective layer 2 facing towards the bearing layer 1 exposed through a width corresponding to the depth of the groove and of the stepped recess in the bearing layer 1. This surface forms one of the side walls of the groove, is designated by 102, and has the same function as in the previous example. The opposite side wall of the groove is formed by the parallel surface 201 of the stepped recess, whereas the bottom of the groove is formed by the end side of the stepped recess 101' .

Here, the thickness of each of the two grooves is smaller than the entire thickness of the bearing layer 1 and is, for example, of the order of a few millimeters or is as thick as the corresponding protective layer 2.

Like in the solution of the previous example, in this variant the sealing edge 4 has rear tongues 104, each of which penetrates in one of the two grooves and sticks by chemico-physical bonding both to the material of the bearing layer 1 and to the material of the protective layers 2 and in this case along the end edge thereof and along the surface bands 102 which outwardly delimit the corresponding groove.

Thus , a smaller amount of valuable material is used, and the groove filling volume is also reduced, wherefore any problem associated to injection

inaccuracies is prevented. The advantages in terms of sealing are as described in the previous example.

A further construction variant, as shown in Fig. 7, differs from that of Fig. 6 in that, while in the example of Fig. 6 the end side of the rest of the thickness of the bearing layer 1 between the two grooves extends flush with the end sides of the protective and/or covering layer/s 2, in the example of Fig. 7, the rest of the thickness of the bearing layer 1 extends beyond the end sides of the protective and/or covering layers 2. This affords a further reduction of the amount of material required to form the sealing edge which, in this case, consists of a wood tongue or the like that is covered along the end side and the two faces parallel to the faces of the panel with a layer of plastic material that forms a sealing enclosure having a substantially inverted U shape and connected by chemico-physical bonding to the material of the bearing layer 1 and to the material of the protective layer/s with which it forms a watertight junction.

Thus , in addition to the enlargement of the contact surface between the material of the sealing edge 4 and the material of the protective layer/s 2, an enlargement of the contact surface between the material of the sealing edge and the material of the bearing layer 1 is also obtained. This provides both improved watertightness and better attachment of the sealing edge 4 to the bearing surface 1 of the panel , whereby a stronger fixation of the edge to the panel is obtained. Fig. 8 shows yet another variant of the panel of Fig. 7 in which one or more rows of through holes 401 are formed in the end extension 301 of the end side of the bearing layer 1 of wood or similar materials , for

the sealing edge material to penetrate therein to form through mechanical anchor members 304 which act as fastening pins or nails, while being formed of one piece with the rest of the sealing edge 4. Therefore, in this embodiment, in addition to mechanical attachment of the sealing edge by chemico-physical bonding of the material of the sealing edge 4 to the panel and particularly to the bearing layer, such sealing edge is attached to the bearing layer 1 by a mechanical form fit.

To understand the importance of the above it shall be noted that, since the connection between the sealing edge 4 and the protective or covering layer/s 2 is designed to especially provide watertightness against moisture or water infiltrations, it has to be subjected to minimal mechanical stresses, such mechanical fastening or retention function of the sealing edge 4 being provided by the connection thereof with the bearing layer 1. Therefore, in this embodiment, the increased mechanical strength of the connection between the sealing edge and the bearing layer further reduces the mechanical stresses acting on the connection between such sealing edge and the protective layer/s.

Fig. 9 shows a further variant embodiment, in which the groove has a bottom with a curved shape, with the groove having an inverted-U cross section. This provides improved distribution of pressures by the material of the sealing edge 4 during injection molding, thereby preventing strong pressures on a corner area from causing the protective layer 2 from lifting from the corresponding face of the bearing layer 1.

Finally, Fig. 10 shows another variant in which

the protective or covering layer/s 2 are applied to the bearing layer 1 with one or more additional layers interposed therebetween, such as fiber layers in the form of fabrics, mats, nonwovens , or else. In this case, the free peripheral band protruding out of the protective layer, which is designated by numeral 102 does not directly stick to the material of the sealing edge 4 , but has additional interposed layers , designated by numeral 5. While this alternative is shown with reference to the variant of Fig. 9, it can be provided in combination with any one of the above variant embodiments . Furthermore , what was said about the variant embodiment of Fig. 10 also applies to the variant embodiment of Fig. 9.

Fig. 11 shows a detail of an end side of a panel according to the embodiment of Figs. 8 and possibly 9 and/or 10. The sealing edge is indicated by dashed lines. The figure clearly shows the extension 301 of the end side of the bearing layer 1 beyond the end side of the protective or covering layer 2. The row of through holes 401 in such extension 301 is also visible. Concerning these holes, in a further variant a row of blind holes or notches may be provided instead of the through holes on one or both opposite faces of the extension 301 of the end side of the bearing layer 1.

Also, referring to Figure 11, the panel is shown with a chamfer or a recessed or removed portion at each of the two corner areas of the end side thereof and through a certain length along a section of the longitudinal edges directly adjacent to such corner areas, whereby the sealing edge also extends along such

corner areas and, by sections 104, along such sections of the longitudinal edge. At the corner areas, the sealing edge 4 complements the shape of the assembly formed by the bearing layer 1 and the protective layer/s 2 to give the finished panel a rectangular shape, whereas along the recessed sections of the two longitudinal sides, the sealing edge sections 104 terminate flush with such longitudinal sides of the panel that are formed by the longitudinal sides of the bearing layer 1 and the protective or covering layer/s 2.

Advantageously, the assembly of the bearing layer 1 and the protective or covering layer/s 2 and the longitudinal edge are conformed according one or more of the alternatives as described and shown with reference to Figures 2 to 10 also along the chamfered corner area and along the recess of the initial section of the longitudinal sides .

Advantageously, the peripheral edge of the assembly of the bearing layer 1 and the covering layer/s along the end side, the corner area and the initial sections of longitudinal sides has a rounded and curvilinear profile at the corner areas and at the end areas of the recessed sections along the longitudinal sides .

According to a further improvement, which may be provided in any combination with one or more of the previous variant embodiments , the panel may have reinforced areas for connection of dismantling tools , such as levers, crowbars or the like. In this case, for instance when the panels are used for retention of poured concrete for slabs or the like, they are dismantled by being lifted or removed using such tools,

which are inserted at the end sides of these panels , i.e. of the sealing edge .

In a first embodiment, to prevent any panel damages caused by mechanical action along the sealing edge, which might cause its separation or weakening of its connection to the panel, at such connection areas the peripheral edge of the layer assembly composed of the bearing layer 1 and the protective or covering layers 2 has one or more recesses 6 along its length, to be filled with the material of the sealing edge 4 whose thickness in these areas is thus greater than the distance between the outer edge of the sealing edge and the edge of the assembly of the bearing layer 1 and protective layers 2. In the embodiment of Figure 12 , three recesses 6 are provided, a central recess in the end side and two side recesses at the ends of the recessed sections of the longitudinal sides of the assembly of the bearing layer 1 and the protective or covering layer/s 2. It shall be noted that the shape of the peripheral edge of the bearing layer and the protective or covering layers 2 also seamlessly extends along such recesses 6.

Figures 13 and 14 show a variant in which the connections for the mounting tools , designated by numeral 7, are elements of plastic or other materials that are incorporated and/or overmolded or anyway embedded or trapped in the material of the sealing edge 4.

In this embodiment, such connections 7 are elements, such as blocks or the like, that have an open cavity at one of their sides and particularly the end side of the sealing edge 4. This affords improved and safer engagement of the end of the lever or another

similar tool and avoids direct application of forces on the sealing edge, while preventing the connection end of the tool against the panel from causing any damage, e.g. in case of accidental slipping or disengagement thereof. As shown by the central element 7 of Figure 13, which is indicated by a dashed line, one or more of these elements 7 may be provided at different areas of the peripheral edge of the sealing edge 4.

Concerning the shape of the peripheral edge of the assembly of the bearing layer 1 and the protective or covering layer/s 2, which have a chamfer at the corner areas and a recess along the initial sections of the longitudinal sides, adjacent to such corner areas, as illustrated by the embodiments of Figure 1 and Figures 11 and 12, the function of this construction is to protect the corner areas , which are more exposed to damages .