EP3292254B1 - Lost formwork panel, assembly of such panels and a method for construction of a concrete floor slab - Google Patents

Description

TECHNICAL AREA

The present invention relates to the field of the manufacture of pre-slabs or concrete compression slabs cast in place by means of formwork panels. More particularly, the invention relates to panels for the production of these slabs or pre-slabs, the assembly of such panels and the process for producing such concrete slabs or pre-slabs.

PRIOR ART

Two main ways of manufacturing concrete compression slabs have been implemented so far.

According to the first way, the method of manufacturing concrete compression slabs cast in place, the underside of which is used as a support for the visible finishing of the ceilings, comprises a shoring system consisting of props and beams connecting the props together. . Formwork plates are then placed on the beams and are provided with a smooth and oiled upper face called the formwork face allowing the stripping of these plates from the lower level after the concrete has hardened.

This process is the cause of many defects that disrupt the progress of building construction sites and cause manufacturing defects. The stripping of the plates presents a safety risk for the operators because they can fall in an unpredictable way. The descent of the reusable formwork plates requires a manual mechanical device cumbersome and difficult to move between floors of a building. This process generates a lot of manual handling to remove the plates from the area after stripping.

In addition, the imperfect junctions between the formwork plates cause defects on the ceilings which then require long operations of sanding and patching the surfaces by hand.

In addition, the coarse surface condition of raw concrete does not allow it to be painted directly, it is necessary to apply at least two coats of smoothing filler before painting.

Reusable formwork plates, which are generally panels of plywood or polymeric materials, degrade and deform as they are reused, which leads to a deterioration in the quality of the finish of the ceilings over time. construction progress. This results in an extension of the duration of the leveling and sanding work of the ceilings before the application of the filling coating and then of the paint.

According to the second way, a usual method consists in setting up pre-slabs, that is to say concrete plates prefabricated in the factory or in fairground prefabrication. Once positioned on the floor formwork area, the pre-slabs serve as a formwork bottom for pouring an additional thickness of concrete working with the pre-slab. This process makes it possible to use a simplified shoring system because the pre-slabs have their own structural strength and incorporate part of the reinforcement of the compression slab.

The major drawback noted on the pre-slab system is the treatment of the joints on the underside of the latter. The joint is treated with a suitable coating, but surface cracks inevitably appear between the pre-slabs due to the shrinkage of the concrete. Pre-slabs are also heavy and expensive to transport. They require large storage areas on the site.

Finally, the installation of networks incorporated into the slab is more complex because the volume of concrete cast in place is less compared to a compression slab entirely cast in place.

The underside of the pre-slabs is made of raw concrete and cannot be painted directly for the aforementioned reasons, the application of a filling coating and mandatory before painting.

The document FROM 1,066,725 discloses a panel according to the preamble of independent claim 1.

DESCRIPTION OF THE INVENTION

A first object of the invention is to remedy the problems of safety, ergonomics and quality of finish when producing compression slabs forming a floor in the field of construction.

Another object of the invention is to provide formwork panels allowing the production of such concrete compression slabs forming a floor.

• une face supérieure dite d'adhérence comportant une surface rugueuse et/ou des moyens d'accroche à la dalle, en creux ou en relief,
• une face inférieure de parement,
• et sur au moins l'un de ses chants, des moyens de liaison à un panneau adjacent sous forme de moyens d'emboîtement et/ou de réservation logeant des éléments de liaison.

To this end, the present invention relates to a lost formwork panel for producing a concrete compression slab forming a floor, said panel constituting, in the cast state of the slab, the lower part of said slab, characterized in that the panel present :

• a so-called grip upper face comprising a rough surface and/or means for gripping the slab, in hollow or in relief,
• an underside of the facing,
• and on at least one of its edges, means for connecting to an adjacent panel in the form of interlocking and/or reservation means housing connecting elements.

This lost formwork panel therefore cooperates with the concrete compression slab cast above it, throughout the life of the structure.

By slab is meant here both a slab produced directly on a construction site, and a slab prefabricated in the factory and transported to the construction site.

The implementation of such a panel makes it possible to eliminate the stripping operation, the time and the associated constraints. In addition, thanks to the structure of the upper face of the panel, the concrete, after it has set, adheres to said panel and the lower facing face of said panel does not require the application of a coating before painting.

Even if it remains attached to the concrete slab throughout the life of the structure, the formwork panel according to the invention does not participate in the structural dimensioning of the concrete compression slab. This is what differentiates it from a pre-slab. After the concrete has set, the formwork panel according to the invention remains integral with the slab and serves as a finishing coating for the underside of the slab.

The attachment means of the upper face of said panel are
undercut-shaped dimples, such as dovetail-shaped dimples.

The casting of the slab, or the pre-slab, requires the assembly of several panels according to the invention comprising means of connection between them. These means of connection to an adjacent panel can comprise means of direct interlocking with said adjacent panel, such as complementary rabbets or groove-tongue type shapes. As a variant, the connecting elements can comprise connector-type elements, which will be detailed later in the description.

According to the invention, the underside of said panel has chamfered edges or tapered edges, constituting housings for the application of a grouting coating and optionally of an anti-cracking tape. between two adjacent panels, which makes it possible to obtain a finish without visible joints and without extra thickness.

The underside of said panel, called facing face, advantageously has a surface of generally planar shape and is preferably light in color. A reflection factor greater than 70%, preferably greater than or equal to 80%, more preferably greater than or equal to 90%, is entirely suitable for constituting the finishing face, such as a ceiling, of the slab or of the pre-slab.

Preferably, the underside of said panel is made of a material having porosity and/or capillarity which also allows it to be covered by a coating and/or a paint.

According to a first embodiment of the invention, the panel is formed from a monolithic block, preferably made of a material based on MgO, MgCl2 and fibers. Advantageously, the fibers are flush with the surface of at least the upper face of the panel to form the rough adhesion face of the concrete. This material based on MgO, MgCl2 and fibers is sufficiently porous to allow, by capillarity, the attachment of a paint, for example.

According to a second embodiment of the invention, the panel comprises a core comprising a material that insulates heat and/or confers acoustic insulation properties on said panel.

For example, the core of said panel may be surrounded by an upper layer and a lower layer each formed of a material comprising fibers coated in a binder, preferably said binder of the upper layer comprising an elastomeric polymer, such than a polymer of the latex or styrene-butadiene type, preferably the binder of the lower layer comprising a material comprising magnesium oxide and magnesium chloride.

The polymer of the upper layer can be a latex polymer emulsion of the EVA ethylene-vinyl acetate type (C ₄ H ₆ O ₂ -C ₂ H ₄ )n) or of the SBR styrene-butadiene type (C ₈ -H ₈ .C ₄ -H ₆ )n , optionally mixed with a hydraulic binder such as Portland cement

The fibers mentioned below can be of any type, but are advantageously glass fibers.

The panel according to the invention is not a structural element of the slab, it has a main role of supporting the concrete poured on its upper face. Consequently, as mentioned above, its thickness is less than a traditional pre-slab. The thickness of the concrete above is large enough to embed reinforcements, electrical, hydraulic or aeraulic connection ducts.

Consequently, according to an advantageous variant, at least the upper face of the panel of the invention has means for receiving elements such as boxes and/or electrical and/or hydraulic connection sheaths, said elements preferably being suitable to be removably mounted to said upper face of the panel. These said receiving means can then advantageously be arranged projecting from said upper face, such as collars of the cable tie type, collars or self-gripping coatings, or be in the form of grooves provided in the upper part of said panel.

• sur la face supérieure, des éléments destinés à être incorporés au béton à couler sur ledit panneau, tels que armatures pour le béton, boîtiers et/ou gaines électriques, hydrauliques et/ou aérauliques, emplacements de portes et fenêtres, de rupteurs thermiques ou de balcons,
• et/ou sur la face inférieure en vue de guider le positionnement de cloisons, soffites du niveau d'étage sous-jacent et/ou d'éléments à fixer audit panneau formant plafond.

According to another variant of the invention, at least one of the faces of said panel can be provided with markers and/or lines capable of positioning it as formwork on the site and of guiding the positioning of additional elements:

• on the upper face, elements intended to be incorporated into the concrete to be poured on the said panel, such as reinforcements for the concrete, boxes and/or electrical, hydraulic and/or aeraulic ducts, locations of doors and windows, thermal breaks or balconies,
• and/or on the underside in order to guide the positioning of partitions, soffits of the underlying floor level and/or elements to be fixed to said panel forming the ceiling.

In a preferred embodiment, the panel according to the invention comprises both means for receiving elements such as boxes, electrical, hydraulic and/or aeraulic connection ducts, reinforcements for concrete and thermal breaks, and markers and/or positioning plots on one or both of its upper and lower faces.

At least one of the faces of said panel may be provided with pre-cuts for adjusting the dimensions of said panel to the limits of the area to be formed and/or for drilling through holes. Such through orifices can for example constitute reserved passages (from one level of floor to another) or to house therein sheaths or through conduits.

The present invention also relates to an assembly of lost formwork panels for the production in elevation of a concrete compression slab forming a floor, comprising panels as described above.

According to a preferred embodiment of the invention, said assembly may comprise, positioned in the reservations made between two adjacent panels, connectors comprising a conical-shaped foot adapting to a housing, in the shape of an inverted V, made between said adjacent panels, surmounted by a rod ending in a head resting on the upper face of the two adjacent panels. The head of said connector can also be conical or rounded in shape to allow stacking for assembling panels with connectors, for storage or transport.

The present invention also relates to a method for producing a concrete compression slab in elevation or for prefabricating concrete compression slabs.

• réalisation de panneaux de coffrage tels que décrit ci-dessus,
• assemblage et étayage desdits panneaux selon un plan prédéfini et des repères numériques et visuels (pour l'orientation) de leur positionnement,
• pose d'armatures, gaines et/ou câblages, pose des boîtiers ou coffrages et mise en place des cloisons suivant des tracés réalisés et/ou à l'aide de moyens de réception prévus sur au moins l'une des faces desdits panneaux,
• coulage du béton sur la face supérieure desdits panneaux.

The method for producing a concrete compression slab in elevation forming a floor advantageously comprises the following successive steps:

• production of formwork panels as described above,
• assembly and shoring of said panels according to a predefined plan and numerical and visual markers (for orientation) of their positioning,
• laying of reinforcements, ducts and/or wiring, laying of boxes or formwork and installation of partitions according to routes made and/or using reception means provided on at least one of the faces of said panels,
• pouring concrete on the upper face of said panels.

• réalisation de panneaux de coffrage tels que décrits ci-dessus,
• assemblage desdits panneaux sur le banc de préfabrication selon un plan prédéfini et des repères numériques et visuels de leur positionnement,
• pose d'armatures, gaines et/ou câblages, réalisation des réservations et mise en place des cloisons suivant des tracés réalisés et/ou à l'aide de moyens de réception prévus sur au moins l'une des faces desdits panneaux,
• coulage du béton sur la face supérieure desdits panneaux.

The process for prefabricating concrete slabs forming a floor advantageously comprises the following successive steps:

• production of formwork panels as described above,
• assembly of said panels on the prefabrication bench according to a predefined plan and numerical and visual markers of their positioning,
• laying of reinforcements, ducts and/or wiring, creation of reservations and installation of partitions according to routes made and/or using reception means provided on at least one of the faces of said panels,
• pouring concrete on the upper face of said panels.

Finally, the present invention also relates to any assembly comprising a concrete slab and at least one panel as described above, produced in accordance with one of the above methods.

BRIEF DESCRIPTION OF FIGURES

• La Figure 1 est une vue de dessus en perspective de la mise en oeuvre de panneaux de coffrage selon la présente invention sur un dispositif d'étaiement ;
• La Figure 2 est une vue de dessus en perspective d'un panneau selon l'invention ;
• La Figure 3 est une vue de dessous en perspective d'un panneau selon l'invention ;
• La Figure 4 est une vue partielle en coupe d'une extrémité d'un panneau munie d'une languette ;
• La Figure 5 est une vue partielle en coupe de deux panneaux adjacents à bords de type rainure-languette ;
• La Figure 6 à est une vue partielle en coupe de deux panneaux adjacents à bords présentant des feuillures complémentaires ;
• La Figure 7 est une vue partielle en perspective d'un panneau montrant un premier bord comportant une languette et un second autre bord une réservation latérale pour une telle languette ;
• La Figure 8 est une vue partielle en coupe de deux panneaux adjacents à bords inférieurs chanfreinés ;
• La Figure 9 est une vue partielle en coupe de deux panneaux adjacents à bords inférieurs amincis ;
• La Figure 10 est une vue en perspective de dessous d'un panneau à bords inférieurs chanfreinés comportant des réservations pour des connecteurs ;
• La Figure 11 est une vue en perspective de dessous d'un panneau à bords inférieurs amincis comportant des réservations pour des connecteurs ;
• La Figure 12 est une vue de côté d'un connecteur ;
• La Figure 13 est une vue partielle en perspective de dessus d'un assemblage de deux panneaux adjacents et d'un connecteur ;
• La Figure 14 est une vue en coupe partielle de deux panneaux superposés avec des connecteurs ;
• La Figure 15 est une vue en coupe d'un panneau comportant une âme en matériau à propriétés isolantes acoustiques ;
• La Figure 16 est une vue de dessus d'un assemblage de plusieurs panneaux selon l'invention équipés de gaines électriques ;
• La Figure 17 est une vue partielle en perspective de dessus montrant un détail d'une connexion électrique prévue sur la face supérieure d'un panneau selon l'invention ;
• La Figure 18 est une vue partielle en perspective de dessus montrant des détails de moyens de réception de câbles électriques disposés sur la face supérieure d'un panneau selon l'invention ; et
• La Figure 19 est une vue de dessus montrant différents repères et tracés sur la face supérieure d'un assemblage de panneaux selon l'invention.

The invention will be better understood on reading the following description of exemplary embodiments, with reference to the appended drawings in which:

• There Figure 1 is a perspective top view of the implementation of formwork panels according to the present invention on a shoring device;
• There Figure 2 is a perspective top view of a panel according to the invention;
• There Figure 3 is a bottom perspective view of a panel according to the invention;
• There Figure 4 is a partial sectional view of one end of a panel provided with a tab;
• There Figure 5 is a partial cross-sectional view of two adjacent panels with tongue-and-groove type edges;
• There Figure 6 to is a partial sectional view of two adjacent panels with edges having complementary rabbets;
• There Picture 7 is a partial perspective view of a panel showing a first edge comprising a tongue and a second other edge a lateral reservation for such a tongue;
• There Figure 8 is a partial sectional view of two adjacent panels with chamfered lower edges;
• There Figure 9 is a partial sectional view of two adjacent panels with tapered lower edges;
• There Picture 10 is a perspective view from below of a panel with chamfered lower edges comprising reservations for connectors;
• There Picture 11 is a perspective view from below of a panel with tapered lower edges comprising recesses for connectors;
• There Picture 12 is a side view of a connector;
• There Figure 13 is a partial perspective view from above of an assembly of two adjacent panels and a connector;
• There Picture 14 is a partial sectional view of two overlapping panels with connectors;
• There Picture 15 is a sectional view of a panel comprising a core of material with acoustic insulating properties;
• There Picture 16 is a top view of an assembly of several panels according to the invention equipped with electrical sheaths;
• There Picture 17 is a partial perspective view from above showing a detail of an electrical connection provided on the upper face of a panel according to the invention;
• There Picture 18 is a partial perspective view from above showing details of means for receiving electric cables arranged on the upper face of a panel according to the invention; And
• There Picture 19 is a top view showing various marks and lines on the upper face of an assembly of panels according to the invention.

Referring to the figures, the panel 1 according to the invention is a formwork panel of rectangular shape, the mechanical characteristics of which are dimensioned so as to resist a point load such as the passage of a man circulating on the formwork before the pouring of the concrete and to resist the thrust of the concrete during its pouring.

The resistance to bending of the panel depends on the span between the structural beams 3 supported by vertical struts 2 of the shoring device provided in the context of its use. This resistance to bending is adjusted by modulating the thickness of the formwork panel according to the shoring system used. The admissible deflection between beams 3 is calculated according to the admissible tolerances of a finished ceiling in the building sector.

The material constituting the formwork panel 1 advantageously has a high dimensional stability, in particular a maximum expansion or shrinkage of preferably 0.2% when it is subjected to the maximum variations in hygrometry and temperatures observed in the zone where the device is implemented. In particular, the material exhibits a maximum expansion or shrinkage of 0.2% when it is covered with concrete in the liquid state.

In the example presented here, the material constituting the formwork panel according to the invention is a composite material consisting of a mineral body 5 formed by the agglomeration of magnesium oxide (MgO -30% to 60%), magnesium chloride (MgCl ₂ -20% to 50%), and perlite (Fe ₃ C - 3% to 15%).

The upper 4 and lower 6 faces (see figure 4 ) include a layer of woven or non-woven glass fibers. These two layers of fiberglass are embedded in the matrix of the body of the panel.

The face called "lower face" 6 ( picture 3 ) of the formwork panel 1 is that which is placed below when the panel is placed on the beams 3 of the shoring device. It is this surface which becomes apparent on the underside of the concrete slab when the shoring device is removed.

The formwork panel according to the invention is characterized by a healthy, smooth, regular underside 6 meeting in particular the requirements of adhesion capacity with all types of water-based paints used as common surfaces in buildings for use as dwelling. The surface has a porosity and a capillarity suitable for the adhesion of such a paint.

The aforementioned mineral composite material responds in particular to these paint adhesion and regularity constraints of the lower face 6. A lower face 6 of the formwork panel produced by means of this composite material has a water absorption capacity of between 5% and 30%, preferably close to 20%, and a light color (surface reflection factor of at least 70%) allowing it to be painted in two color coats.

The lost formwork panel 1 according to the invention has, on its four edges, connection means to adjacent panels, making it possible to ensure continuity between several panels of identical design assembled end to end. The connecting means make it possible in particular to ensure the flatness between the panels 1 in order to correspond to the flatness requirements of the supports ready to paint and serve to ensure the seal so that the concrete cannot flow between the panels 1.

• l'assemblage de type "bouvetage" (figure 5). Le panneau comporte alors des portions en saillie de type languette 8 sur deux de ses tranches contigües et des portions en retrait des tranches, de type rainures 9 de forme complémentaire sur les deux autres tranches. Ces bouvetages sont dimensionnés de manière à former un emboîtement lorsqu'on joint plusieurs panneaux (figure 1) l'un à côté de l'autre pour former un ensemble extensible à l'infini (figure 1). L'emboîtement (figure 5) permet de garantir un ajustement et un affleurement précis des panneaux 1 entre eux et compense les éventuels défauts de réglage du dispositif d'étaiement. Un tel assemblage permet d'assurer un jointoiement hermétique entre les panneaux 1 et empêche ainsi l'écoulement de béton entre les panneaux.
• l'assemblage de type "tenon-mortaise" ou "lamelles" (figures 4 et 7). Le panneau présente alors des tenons ou lamelles 12 réparties à intervalles réguliers sur deux tranches contigües et des réservations 13 de forme complémentaire, taillées dans la tranche et situées exactement aux mêmes intervalles sur les deux autres tranches. Ces appendices sont dimensionnés de manière à former un emboîtement lorsque qu'on joint plusieurs panneaux 1 l'un à côté de l'autre pour former un ensemble extensible à l'infini (figure 1). Cet assemblage est moins étanche que le précédent entre les panneaux 1 lors du coulage du béton. Il est alors prévu un bord supérieur chanfreiné 15 sur toutes les arêtes de la face supérieure (figure 8). Ces bords chanfreinés 15 servent de réservation pour l'application d'un joint élastomère d'étanchéité après assemblage des panneaux sur le site de réalisation du coffrage.
• l'assemblage de type "recouvrement" (figure 6). Le panneau 1 présente alors des bords à feuillures 10 et 11 complémentaires, ménagées respectivement au niveau de la face supérieure pour deux bords contigus (exemple de la feuillure 11) et au niveau de la face inférieure pour les deux autres bords (exemple de la feuillure 10). Lorsqu'on assemble plusieurs panneaux de coffrage (comme sur représenté sur la figure 1), ces formes permettent de recouvrir une feuillure sur une autre feuillure de forme inverse. L'emboîtement permet de garantir un ajustement et un affleurement précis des panneaux 1 adjacents entre eux et compense les éventuels défauts de réglage du dispositif d'étaiement. Cet assemblage permet d'assurer un jointoiement hermétique entre les panneaux et évite ainsi l'écoulement de béton entre les panneaux.
• l'assemblage aux moyens de "connecteurs" 18 (voir figures 12, 13, 14) qui sont répartis sur deux bords contigus de chacun des panneaux à assembler. Dans l'exemple présenté sur les figures 12 et 13, les connecteurs 18 comprennent un pied 19 de forme conique s'adaptant à un logement, en forme de V inversé, ménagé entre les bords inférieurs des panneaux adjacents. Ce pied 19 est surmonté d'une tige 20 se logeant dans les réservations 17 (voir les figures 10 et 11) ménagées dans les chants des panneaux, et se terminant par une tête 21 s'appuyant sur la face supérieure 4 des deux panneaux adjacents.

The connecting means allow for example the following assemblies:

• the "bouvetage" type assembly ( figure 5 ). The panel then comprises protruding portions of the tongue type 8 on two of its adjoining edges and recessed portions of the edges, of the groove type 9 of complementary shape on the other two edges. These grooves are sized so as to form an interlocking joint when several panels are joined ( figure 1 ) next to each other to form an infinitely expandable set ( figure 1 ). The nesting ( figure 5 ) makes it possible to guarantee precise adjustment and flushness of the panels 1 with each other and compensates for any faults in the adjustment of the shoring device. Such an assembly makes it possible to ensure hermetic jointing between the panels 1 and thus prevents the flow of concrete between the panels.
• the "tenon-mortise" or "slats" type assembly ( figure 4 And 7 ). The panel then has studs or slats 12 distributed at regular intervals over two adjoining edges and reservations 13 of complementary shape, cut in the edge and located at exactly the same intervals on the other two edges. These appendages are sized so as to form a nest when several panels 1 are joined next to each other to form an infinitely extendable assembly ( figure 1 ). This assembly is less tight than the previous one between the panels 1 during the pouring of the concrete. There is then provided a chamfered upper edge 15 on all the edges of the upper face ( figure 8 ). These chamfered edges 15 serve as a reservation for the application of an elastomeric seal after assembly of the panels on the formwork production site.
• the "covering" type assembly ( figure 6 ). The panel 1 then has edges with complementary rabbets 10 and 11, provided respectively at the level of the upper face for two contiguous edges (example of the rabbet 11) and at the level of the lower face for the two other edges (example of the rabbet 10). When combining several formwork panels (as shown on the figure 1 ), these shapes make it possible to cover a rebate on another rebate of the opposite shape. Interlocking makes it possible to guarantee a precise adjustment and flushness of the panels 1 adjacent to each other and compensates for any faults in the adjustment of the shoring device. This assembly ensures hermetic jointing between the panels and thus prevents the flow of concrete between the panels.
• assembly by means of "connectors" 18 (see figure 12 , 13, 14 ) which are distributed over two contiguous edges of each of the panels to be assembled. In the example shown on the figure 12 And 13 , the connectors 18 comprise a foot 19 of conical shape adapting to a housing, in the shape of an inverted V, formed between the lower edges of the adjacent panels. This foot 19 is surmounted by a rod 20 which is housed in the reservations 17 (see the figures 10 and 11 ) made in the edges of the panels, and ending in a head 21 resting on the upper face 4 of the two adjacent panels.

The reservations 17 made in the edges of the panels make it possible to define the precise positioning of these connectors 18 and ensure the maintenance by interlocking of the connectors in their predefined position on said panel. These reservations 17 in the edges make it possible to adjust the panels 1 against each other without any gap, thus making it possible to ensure maximum sealing during the pouring of the fresh concrete (see figure 13 ).

If necessary, the edges of said panel which are devoid of connectors also have reservations whose shape is designed to match the shape of the connectors fixed on another identical plate when these two plates are positioned side by side, whether in the direction of the width or in the direction of the length, the panels assembled between them always being oriented in the same direction. These reservations can then also act as keying device when assembling the panels on site.

The shape of the connectors 18 is designed to allow the panels to be superimposed during their storage: the base of the foot 19 is hollowed out to receive the conical or rounded head 21 of said connector and thus allow the assembly of panels with connectors to be stacked.

The upper face 4 (see picture 2 ) of the lost formwork panel 1 according to the invention has means of attachment with the concrete of the slab after it has hardened.

• une ou plusieurs réservations 7 non débouchantes (schématisées sur les figures 2, 4, 8, 9) sont taillées dans la face supérieure 4 du panneau de coffrage perdu 1. La (ou les) réservations ont une forme en contre-dépouille, empêchant un corps liquide durci de s'en défaire. Il peut s'agir d'une forme en queue d'aronde avec un profil trapézoïdal (comme schématisé sur les figures 2, 4, 8 et 9) dont la base large est située dans le fond de la réservation ou tout autre profil présentant un élargissement par rapport à la largeur mesurée en surface du panneau. Ces moyens d'accroche par réservations ayant une forme de contre-dépouille constituent des moyens de liaison indémontables du panneau avec le béton coulé en place sur sa face supérieure (figure 2) et qui vient s'emprisonner dans ces réservations une fois qu'il a fait prise. La ou les réservations sont de préférence uniformément réparties sur la surface supérieure 4 (figure 2) afin d'assurer la répartition de la charge sur toute la surface du panneau de coffrage perdu 1.
• un ou plusieurs appendices sont fixés sur la face supérieure (figure 2) du panneau de coffrage perdu et font saillie à la surface du panneau. La forme du ou des appendices présente alors obligatoirement une contre-dépouille empêchant de le ou les dissocier du béton durci après qu'il ait été coulé sur la surface supérieure 4 du panneau de coffrage. L'assemblage du ou des appendices au panneau de coffrage peut être réalisé par collage, fixation mécanique, ou assemblage de formes complémentaires. Ce type d'assemblage est privilégié lorsque l'épaisseur du panneau est trop faible pour réaliser une réservation dans la matière du corps du panneau. Le ou les appendices d'accroches peuvent également servir de cale pour la pose d'une éventuelle nappe d'armatures métalliques sur le coffrage qui seront enrobées lors du coulage du béton et formeront un béton armé. L'appendice permet alors de maintenir une distance de quelques centimètres (par exemple 2 à 5 cm) d'enrobage de béton entre le panneau de coffrage perdu et la nappe d'armatures.

The connection with the concrete can be created in several ways:

• one or more non-opening reservations 7 (schematized on the figure 2 , 4 , 8, 9 ) are cut in the upper face 4 of the lost formwork panel 1. The reservation(s) have an undercut shape, preventing a hardened liquid body from getting rid of it. It may be a dovetail shape with a trapezoidal profile (as shown on the figure 2 , 4 , 8 and 9 ) whose wide base is located in the bottom of the reservation or any other profile having a widening in relation to the width measured at the surface of the panel. These fastening means by reservations having a form of undercut constitute means of unremovable connection of the panel with the concrete cast in place on its upper face ( figure 2 ) and who comes to imprison himself in these reservations once he has taken hold. The reservation or reservations are preferably uniformly distributed over the upper surface 4 ( figure 2 ) in order to ensure the distribution of the load over the entire surface of the lost formwork panel 1.
• one or more appendages are attached to the upper surface ( figure 2 ) of the lost formwork panel and protrude from the surface of the panel. The shape of the appendage(s) then necessarily has an undercut preventing it or them from being separated from the hardened concrete after it has been poured onto the upper surface 4 of the formwork panel. The assembly of the appendix or appendages to the formwork panel can be achieved by gluing, mechanical fixing, or assembly of complementary shapes. This type of assembly is preferred when the thickness of the panel is too small to make a reservation in the material of the body of the panel. The attachment appendix(es) can also be used as a shim for laying a possible layer of metal reinforcement on the formwork which will be coated during the pouring of the concrete and will form a reinforced concrete. The appendage then makes it possible to maintain a distance of a few centimeters (for example 2 to 5 cm) of concrete cover between the lost formwork panel and the layer of reinforcement.

In the case where the desired finish of the smooth ceiling should not allow any gap to appear between the adjacent panels 1, a jointing system partially integrated into the panel is then provided.

• les quatre bords du panneau de coffrage perdu sont des bords amincis 16, sur la face inférieure 6 (figure 3) uniquement, par exemple d'une profondeur de un à trois millimètres et sur une largeur de soixante millimètres au maximum. La mise en place bout à bout des bords amincis 16 de deux panneaux de coffrage adjacents offre une réservation permettant la pose ultérieure d'une bande anti-fissuration collée et enduite en plusieurs passes avec un enduit adapté au matériau support sans générer de surépaisseur apparente à l'oeil nu. La bande est collée dans la réservation crée par les bords amincis 16 (voir figure 9) de chacun des deux panneaux adjacents assemblés.
• les quatre bords du panneau de coffrage perdu sont des bords chanfreinés 14 sur sa face inférieure 4 (figure 8). Le chanfrein présente un angle ouvert, de préférence supérieur à 45° afin d'offrir une surface d'accroche maximale pour l'enduit de rebouchage.

Grouting can, for example, be done in two ways:

• the four edges of the lost formwork panel are tapered edges 16, on the underside 6 ( picture 3 ) only, for example with a depth of one to three millimeters and a width of sixty millimeters at most. The end-to-end positioning of the thinned edges 16 of two adjacent formwork panels provides a space allowing the subsequent laying of an anti-cracking strip bonded and coated in several passes with a coating adapted to the support material without generating any apparent excess thickness. the naked eye. The strip is glued in the reservation created by the tapered edges 16 (see figure 9 ) of each of the two adjacent panels assembled.
• the four edges of the lost formwork panel are chamfered edges 14 on its underside 4 ( figure 8 ). The chamfer has an open angle, preferably greater than 45° in order to provide a maximum adhesion surface for the filler.

The reservation formed by the positioning end to end of the chamfered edges 14 of two adjacent panels allows the subsequent application of a specially dedicated filler coating. After the filler has dried, it is possible to apply a finishing coat to permanently hide the junction between the two panels.

The permanent formwork panel according to the invention 1 can be placed at the bottom of the formwork on the marble of an industrial or fairground prefabrication bench. After stripping the slab, the formwork panels cooperate with it permanently and irreversibly. They thus serve as a permanent finishing coating for the underside of the precast slab. This arrangement makes it possible to paint the underside of the prefabricated slab directly without any prior preparation of the support.

In the example shown schematically in figure 15 , the panel 1 comprises a core 22 comprising a thermally insulating material and/or conferring acoustic insulation properties on said panel, interposed between an upper layer 24 with a rough upper face 4 and a lower layer 26 with a lower face 6 ready to paint .

Each of the upper 24 and lower 26 layers can be formed from a material comprising fibers, such as glass fibers, coated in a binder. The binder of the upper layer 24 can comprise an elastomeric polymer, such as a polymer of the latex or styrene-butadiene type, optionally mixed with cement, such as Portland cement. The binder of the lower layer 26 can be a material comprising magnesium oxide and magnesium chloride.

The core 22 can be formed from a high resilience material whose sound absorption coefficient αw is greater than 0.10 (according to the ISO 11654 standard) for sound frequencies ranging from 0 to 40,000 Herz. After pouring the slab, and dismantling the shoring device, said resilient core is found between two rigid walls called masses: the top mass is made up of concrete which generally has a density of 2.4 to 2.8, the mass below is the lower layer 26 of the formwork panel 1 with a density greater than 1.

The assembly thus created constitutes a mass/spring/mass system which improves the acoustic performance of the slab + panel(s) assembly, in particular in the category of airborne noise and in the category of impact noise perpetrated on the floor of the level higher than the slab as well as on the ceiling of the lower level.

In order to further facilitate work on the construction site, the panels 1 can advantageously be equipped, on their upper face 4 and/or on their lower face 6, with means for receiving elements such as boxes 30 or sheaths 31 for connections electric, hydraulic and/or aeraulic, said elements preferably being capable of being removably mounted on said upper face 4 of the panel.

For example, as shown in the figures 16, 17 And 18 ) these panels can be pre-equipped with receiving means arranged projecting from said upper face 4, such as collars 25 of the cable tie type, collars or self-gripping coatings, for example in the form of self-gripping pads glued to the surface: the housing bases 30 also having hook-and-loop zones can thus be positioned quickly, precisely and removable.

Said reception means can also be in the form of grooves formed in the upper part of said panel.

These pre-equipment of the panels 1 thus allows a positioning of the casings 30 of formwork and ducts 31 of precise and fast connection because it does not require the reading of a plan and the measurement by manual measuring means (tape measure); This positioning of the formwork boxes on the panels 1 nevertheless remains flexible because it can be, if necessary, shifted by a few millimeters to circumvent reinforcements for the concrete. The boxes 30 can also easily be detached and then put back in place.

• sur la face supérieure 4, des éléments destinés à être incorporés au béton à couler sur ledit panneau, tels que armatures pour le béton, réseaux électriques, hydrauliques et/ou aérauliques, emplacements de portes et fenêtres, de rupteurs thermiques ou de balcons,
• et/ou sur la face inférieure en vue de guider le positionnement de cloisons (tracés 28 sur la figure 19), soffites du niveau d'étage sous-jacent et/ou d'éléments à fixer audit panneau formant plafond.

In addition, at least one of the faces of said panel can be provided with markers 27 and/or lines 28,29 (see figure 19 ) able to position it as formwork on the site and to guide the positioning of ancillary elements:

• on the upper face 4, elements intended to be incorporated into the concrete to be poured on said panel, such as reinforcements for the concrete, electrical, hydraulic and/or aeraulic networks, door and window locations, thermal breaks or balconies,
• and/or on the underside in order to guide the positioning of partitions (lines 28 on the figure 19 ), soffits of the underlying floor level and/or elements to be fixed to said ceiling panel.

Thus each plate is identified by a numbering 27 which corresponds to the order of laying and refers to a plan. The plots 28 correspond to the actual layout in space and to the actual scale of the reinforcements, networks and casings 30 which must be incorporated into the concrete slab and put in place before it is poured. All of these markers and lines serve as a guide for operators to position the material to be incorporated into the slab.

The assembly of the formwork plates then forms a puzzle ( figure 19 ) on which appears all the information useful for the construction of the building in the form of a floor plan of the building in real scale. The operator no longer needs to refer to a paper plan, nor to use measuring tools to position the various elements. Measurement errors and positioning are then considerably reduced, or even eliminated. This also results in a huge time saving on the construction site.

Claims (18)

1. A non-structural lost formwork panel (1) for making a concrete compression slab forming a floor, said panel constituting, the bottom portion of said slab once the slab has been cast, the panel presenting:

   - a so-called adhesion top face (4) comprising attachment means to the slab, these so-called attachment means being sockets of undercut shape, such as sockets (7) of dovetail shape,

   - a bottom face (6) forming a facing,

   - on at least one of its edge faces, connection means for connection to an adjacent panel in the form of means for mutual engagement and/or of a recess housing connection elements,

   characterized in that the lower face (6) includes chamfered edges (14) or thinned edges (16), constituting housings for applying a jointing coating and possibly an anti-cracking strip between two adjacent panels.
2. The panel according to claim 1, characterized in that the top face has a rough surface.
3. The panel according to one of claims 1 or 2, characterized in that the means for connecting to an adjacent panel comprise means for direct engagement with said adjacent panel, such as complementary rabbets (10, 11) or shapes of the tongue (8) and groove (9) type.
4. The panel according to any one of the preceding claims, characterized in that the connection means comprise connector-type elements (18).
5. The panel according to any one of the preceding claims, characterized in that the bottom face (6) of said panel, called facing, has a surface of generally plane shape and is preferably light in color.
6. The panel according to any one of the preceding claims, characterized in that the bottom face (6) of said panel is made of a material having porosity and/or capillarity allowing it to be covered by a coating and/or paint.
7. The panel according to any one of the preceding claims, characterized in that it is constituted by a single-piece block, preferably made of a material based on MgO, MgCl₂, and fibers.
8. The panel according to any one of claims 1 to 6, characterized in that it includes a core (22) comprising a thermally insulating material and/or imparting soundproofing properties to said panel.
9. The panel according to claim 8, characterized in that the core (22) is surrounded by a top layer (24) and a bottom layer (26) each formed by a material including fibers coated in a binder, preferably said binder of the top layer comprising an elastomer polymer, such as a latex- or styrene-butadiene-type polymer, and preferably the binder of the bottom layer comprising a material including magnesium oxide and magnesium chloride.
10. The panel according to any one of the preceding claims, characterized in that at least the top face (4) of said panel has reception means for receiving elements such as boxes and/or conduits for electrical and/or hydraulic connections, said elements preferably being suitable for being releasably mounted on said top face of the panel.
11. The panel according to claim 10, characterized in that the reception means are arranged projecting from said top face (4), such as collars of cable clamp type, collars, or self-gripping coverings, or are in the form of grooves formed in the top portion of said panel.
12. The panel according to any one of the preceding claims, characterized in that at least one of the faces (4, 6) of said panel has markers and/or lines suitable for positioning it as formwork on site and for guiding the positioning of auxiliary elements:

    - on the top face, elements for being incorporated in the concrete that is to be cast on said panel, such as reinforcement for the concrete, electrical, hydraulic and/or air-flow boxes and/or conduits, locations for doors and windows, thermal barriers, or balconies; and/or

    - on the bottom face for guiding the positioning of partitions, soffits for the underlying floor, and/or elements that are to be fastened to said ceiling-forming panel.
13. The panel according to any one of the preceding claims, characterized in that at least one of the faces of said panel is provided with cutouts for adjusting the dimensions of said panel to the limits of the area to be covered in formwork and/or for forming through orifices.
14. An assembly of lost formwork panels for the making in elevation of floor-forming concrete compression slab, comprising the panels according to any one of the preceding claims.
15. The assembly of panels according to claim 14, characterized in that it comprises, positioned in the recesses (17) formed between two adjacent panels (1), connectors (18) comprising a foot (19) of conical shape fitting in a housing of upside-down V-shape that is formed between said adjacent panels, and surmounted by a rod (20) terminating by a head (21) bearing against the top faces of two adjacent panels.
16. A method of making in elevation a floor-forming concrete compression slab, comprising the following successive steps:

    - making formwork panels according to any one of claims 1 to 13;

    - assembling and propping said panels according to a predefined plan and with numerical and visible markers of their positioning;

    - laying or reinforcements, sheath and/or cabling, laying boxes or formworks, and putting partitions into place in compliance with lines made on at least one of the faces of said panels and/or with the help of reception means provided on at least one of the faces of said panels; and

    - casting concrete on the top face of said panels.
17. A method of prefabricating floor-forming concrete slabs comprising the following successive steps:

    - making formwork panels according to any one of claims 1 to 13,

    - assembling said panels on the prefabrication bench according to a predefined plan and with numerical and visible markers of their positioning;

    - laying reinforcements, sheath and/or cabling, making reservations and putting partitions into place in compliance with lines made on at least one of the faces of said panels and/or with the help of reception means provided in at least one of the faces of said panels;

    - casting concrete on the top faces of said panels.
18. An assembly comprising a concrete slab and at least one panel (1) according to any one of claims 1 to 13 made according to one of the methods of claims 16 or 17.

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