AU2012360752B2

AU2012360752B2 - Panel intended to form a lost form panel for the production of walls

Info

Publication number: AU2012360752B2
Application number: AU2012360752A
Authority: AU
Inventors: Guy Sarremejeanne
Original assignee: INGEREC
Current assignee: INGEREC
Priority date: 2011-12-30
Filing date: 2012-10-24
Publication date: 2015-09-10
Anticipated expiration: 2032-10-24
Also published as: FR2985275B1; AU2012360752A1; FR2985275A1; EP2798129A1; WO2013098495A1; BR112014015704A8; IN2014CN04411A; BR112014015704A2

Abstract

The invention relates to a panel (1) intended to form a lost form panel for the production of walls, said panel (1) comprising a plurality of circular recesses (10) parallel to each other and each extending between a so-called upper ridge (AS) and a so-called lower ridge (AI) of the panel, said circular recesses (10) being distributed over the whole of the panel (1) between two lateral edges (RL) and being separated by a distance of between 3 centimetres and twice the diameter of the circular recesses (10), a sealing line (11) positioned at the bottom of the panel connecting the circular recesses (10) and perpendicular to said recesses, and at least one so-called side locking opening (12) between each lateral edge (RL) and the closest circular recess (10).

Description

Title of the invention Panel intended to form a lost form panel for the production of walls' 5 gBackround of the invention The present invention relates to the general field of panels used in the field of constructing buildings easily and quickly. Numerous products are known for this purpose. There thus exist prestressed beams, prestressed 10 pre-slabs, and honeycomb slabs for constructing floors. In this context, solutions are being developed in the construction industry to enable walls to be constructed easily and quickly. The products to which the invent ion applies are semi-finished products, where 15 such smi-finished products constitute temporary stages for use in constructing vertical concrete structures for the fabric of building and civil engineering works without having recourse to reusable materials for providing shuttering. The use of such conventional 20 shuttering means constitutes a technique requiring a large amount or specialized labor, which the building industry would like to reduce or eliminate. The idea is to propose a semi-finished product that acts as a permanent form in the wall as finally obtained. 25 In presently-known products, two concrete plates that are 5 centimeters (cm) to 7 cm in thickness, known as "pre-slabs" are associated with each other, being placed face t face and spaced apart by reinforcing bars connecting the two concrete plates together in order to SO constitute a "precast wall". A precast wall of this type is described, for example, in US 4 731 971. The method of fabricating such semi-finished products implies casting a first thickness of concrete in which reinforcing bars are arranged. After thermal 35 maturing, the resulting first concrete plate together Translation of ,he title as established ex cfficio with the included reinforcing bars is extracted from the mold and another slab is fabricated in the same manner. The first concrete plate is then turned over before the concrete of the second concrete plate has hardened so as 5 to embed the reinforcing bars of the first concrete plate in the concrete of the second plate. At the end of the thermal maturing for solidifying the assembly, the horizontal mold that was used for casting the concrete is tilted up and the semi-finished 10 product as obtained in that way is handled and stored vertically prior to being installed in a likewise vertical wall. Various aspects are liable to increase the cost of precast walls: firstly, since the duration of each 15 thermal-maturing cycle is of the order of thirteen hours, it can be seen that when using that technique equipment is unavailable for two cycles and is thus less productive. This doubling of the thermal maturation cycle time is incompressible. Secondly, the industrial 20 tool needed by the method involves installations that are cumbersome and expensive. Nevertheless, such precast walls are in more and more widespread use, insofar as they provide savings in terms of specialized labor. In contrast, although transporting presently 25 available semi-finished products is inexpensive because of their small bulk and weight, the need to transport precast walls vertically is expensive. Given the small thickness of the two pre-slabs used, once the panel is inclined, its stiffness in its plane leads to excessive 30 deformation that always leads to the assembly breaking whenever semi-finished products are not transported vertically. This problem of handling and transport is to be observed even when using concrete that presents a Young's modulus that is high. 35 Thus, road transport requires special equipment, generally trailers that allow the elements to be left on site so as to avoid taking trucks out of service while 3 the trailers are being unloaded, and so as to avoid taking worksite cranes out of service to perform intermediate storage operations. This avoids making use of any handling equipment. However it involves managing 5 trailer logistics so as to enable empty trailers to be recovered in order to be reloaded and reused for other deliveries. Finally, i is known that using precast walls on site requires them to be stabilized vertically by means 10 of push-pull props fastened to concrete blocks weighing about 500 kilograms (kg) to 1 (metric) tonne (t) Another weakness of precast walls is observed during a temporary stage while a portion of the work is not final and needs to be stabilized. With precast walls, it 15 is not possible to install antd stack higher structures, typically floor type. horizontal structures, on such walls before the concrete has been cast. Nor is it possible to cast the concrete on a single occasion for both the vertical and the horizontal structures, Under the effect 20 of a load applied vertically on its top margin, a precast wall that has not already been filled with concrete will warp and impair the stability of the work and the safety of people. With precast walls, it is therefore necessary for 25 the wall to be comletely stabilized during casting and for the concrete to be complIetely hydrated before a floor is put into place, This lengthens the time required for constructing and building works. it is also known that even though precast walls 30 enable openings of the window or door type to be incorporated initially in the wall, such integration involves having recourse to using shuttering made of wood to stop the concrete at the outl ines of the openings between the two facing walls. A precast wall thus laks 35 flexibility concerning finishings of the window and sill type and remains restricted to relatively marginal uses.

4 To sum up, the use of precast walls is relatively expensive, since in 60% of situations it is found that costs are 50% to 60% greater than the costs of conventional techniques. 5 Also, the absence of in-plane stiffness and the impossibility of superposing elements and of making the walls and the floors of a building in a single stage are weaknesses from the point of view of speed of construction. 10 Other products constituted by honeycomb slabs are also known from GB 1 127 219. Those honeycomb slabs for fabricating floors are not suitable for constructing walls. 15 Object and summary of the invention An object of the present invention is to mitigate the drawbacks of precast walls and to propose a product that is to be finished off by casting concrete in the construction of walls in a manner that is easy and fast, 20 while also enabling the semi-finished product constituting a permanent form to be handled freely. The invention thus provides a panel for constituting a permanent form for fabricating walls, the panel forming a monolithic block of concrete and presenting: 25 a plurality of circular section cylindrical cavities referred to as "circular cavities" that are mutually parallel and that extend in a longitudinal direction of the panel between a "top" edge face and a "bottom" edgoe face of the panel, these circular cavities 30 being distributed all along the panel between two side edge faces and spaced apart by a distance lying in the range 3 centimeters (cm) to twice the diameter of the circular cavities in the transverse direction perpendicular to the longitudinal direction of the panel, 35 and preferably regularly spaced apart in said transverse direction; a fastening duct placed at the foot of the panel connecting together the circular cavities and extending perpendicularly thereto, the fastening duct being for illing with concrete when the panel is used; 5 1 a bottom fdge race forming a continuous "bottom" recess over its length in said transverse direction, being delimited by two bottom "bearing" margins extending in sa id tran sverse erection and preferably arranged symmetrically relative to a transverse longitudinal 10 midplane of the panel, the bottom recess being for filling with concrete when the panel is used as a permanent form; an asymmetric top edge face forming a continuous "top" recess extending over its entire length in said 15 transverse direction between a "support" top margin suitable for receiving and supporting a horizontal slab, and a "retention" top margin, the support and retention top margins extending along the length of the top edge face in said transverse direction, said support top 20 margin being at a height higher than said retention top margin, said retention margin being suitable for retaining concrete cast over said horizontal slab resting on said support top margin; and metal reinforcing bars incorporated in the 25 concrete outside said circular cavities and said fastening duct, extending at least along the length of the panel in said transverse direction of the panel; and side edge faces each forming a side recess, each being delimited by two "side" margins, said side edge 30 faces and said side margins extending in said longitudinal direction, preferably symmetrically relative to a said transverse longitudinal m.idplane of the panel, each said side recess being continuous over the entire length of each said side edge face in the longitudinal 35 direction of the panel, each side recess being for filling with concrete when joining the panel with a side edge face of another panel while fabricating a wall, side 6 bars projecting from said side edge faces extending outside the panel in said transverse direction of the panel; and , at least one "bonding" side cavity in each side 5 edge face extending in said transverse direction between an opening in eacn side edge face and the nearest circular cavity, Preferably, the panel has a single said fastening duct. 10 It can be 'nderstood that: said panel has two parallel opposite plane main faces with the top, side, and bottom edges of the two faces delimiting said top, side, and bottom edge faces respectively that form the edges on the edge face of the 15 thickness of the panel; and - each of the two parallel opposite main faces of the panel is delimited by a top margin, two side margins, and a bottom margin; and the "longitudinal" and "transverse" directions 20 correspond to the vertical and horizontal directions respectively of the two parallel opposite main faces of the panel when said panel is vertically in place for use as a prefabricated wall element; and * the "top" and "bottom" positions correspond to a 25 position in which said panel is vertically in place to be used as a prefabricated wall element; and -the top and bottom edge faces are situated at the two ends of the panel in the longitudinal direction and they extend in said transverse direction perpendicular to 30 the longitudinal direction of the panel; and * the side edge faces are situated at the two ends of the panel in the transverse direction and they extend in said longitudinal direction of the panel; and * said longitudinal and transverse midplane of the 35 panel is a plane parallel to the two parallel opposite main faces of the panel, said midplane extending in the longitudinal and transverse directions of the panel; and 7 the top and bottom edge faces present sections in a vertical longitudinal plane perpendicular to the two opposite parallel faces of the panel, i.e. in the thickness of the panel as defined by said two top margins 5 or two said bo ttom margins, respectively, in the shape of concave or hollow outlines, and said side edge faces present sections in a transverse plane perpendicular to the two opposite parallel faces of the panel, i.e. likewise in the thickness of the panel as defined by two 10 of said side margins, with an outline shape that is convex or hol low; and the term "margin" is used broadly herein, since each of said margins presents its own small plane outer free face perpendicular to the opposite faces of the 15 panel, each said small face delimzs.ing one end of a said main face of the panel, each said small plane edge face thus being suitable for acting as a bearing face or as a support face. The invention proposes using the principle of 20 honeycomb slabs with a particular structure specifically adapted to constructing walls with side, top, and bottom junctions that are optimized for easy and fast const rucoion. The use of mutually parallel circular cavities makes 25 it possible to obtain a lightweight honeycomb structure wh ile providing very good behavior from the point of view of arch effects under the effect of hydrostatic pressure. The stresses on the circular cavities are isotropic, in contrast to cavities of other sections, and the stiffness 30 that is obtained is optimized. Th.-is enables panels obtained in this way to be handled very freely, with panel stiffness being close to that of a solid slab, even when though the weight of the semi-finished product is much less than the weight of a solid slab. 35 Thus, the circular cavities and the fastening duct make it possible for panels to be installed in walls in highly effective and reliable manner, When solid slabs B are used, concrete can be cast only over the sides of the panels, thereby reducing bonding properties at the foot of the wall. One of the advantages of the semi-finished products s of the invention is to enable the concrete to be cast as a single piece in and between two adjacent panels and at the interface with horizontal structures on which they are placed. The bonding together of two panels placed laterally relative to each other is thus optimized with 10 semi-firished products of the invention, whereas with solid panels, it is known that the result obtained is unsatisfactory from a mechanical point of view. Once filled with concrete by casting concrete into one of said vertical circular cavities, the bonding 15 channel provides communication between the vertical circular cavities and optimizes continuity of concrete simultaneously in the horizontal direction and the vertical direction, at the foot of the panel, in the zone where hydrostatic pressure is at its greatest, and in the 20 vicinity of nodes of the structure constituted by points where walls made up of said panels converge with floors or lower structures on which the panels are placed. In addition, using a permanent form in accordance with the invention enables better incorporation of the 25 concrete of the first stage within the final volume by providing greater contact area with the concretes of the second stage. This makes it possible to limit micro cracking. Concretes of the first and second stages should be understood as being two concretes that are 30 bonded together but that were incorporated at different instants or ages in order to form a final monolithic assembly. Because of the continuous bottom recess in the bottom edge face, a maximum contact area is obtained between the first stage concrete of a lower structure 35 that is already in place on which the panel is placed, and the second stage concrete that is cast into the bottom recess via the circular cavities.

9 Because the reinforcing bars lie outside the circular cavities, they are situated relatively close to the main outside faces of the panel, thereby providing the panel with better bending strength. In addition, 5 with precast walls, the distance between the reinforcement and the bare outside face of the walls is about 6 cm. This arrangement is likely to encourage micro-cracking to form because the interface between the two plates is "dry" over 5 cm. The surface indentations 10 during casting of the concrete move the reinforcing bars 1 cm further away from the outside face, With a permanent form, this distance is only 3 cm, i.e. the thickness of concrete that is present between the circular cavities and the outside face. In addition, the 15 interface between two permanent forms, situated at the side edge faces, is not a dry interface since it is used for bonding together the concretes of the first and seconds stages. This arrangement tends to limit micro crack initiation. The dry interface is of only 2 cm with 20 a permanent form. Overall, the interface area is 1.5 times greater. Because of the combination of continuous side recesses fitted with side bars projecting from said transverse bonding cavities, good side bonding is 25 obtained using a single continuous transverse cavity of said fastening duct. With the invention, the advantages of slabs with square section channels are combined with the advantages of precast walls when making the junction between two 30 panels placed side by side or one above the other. In addition, it should be observed that the presence of top, bottom, and side recesses on each of the panels makes it possible to obtain weight that is even lower and to cast concrete that forms a single block bonded inside each 35 panel and between the two panels by filling the side or top/bottom recesses.

10 Not having side or top/bottom recesses would lead to junctions between the two panels of doubtful quality that could lead very quickly to defects in the construction. It should be observed that with the invention, the 5 presence of the side bonding opening between each side edge face and the closest circular cavity is essential, since it enables a single piece of concrete to ne created during casting between the circular cavities and the side recesses because of the link, after filling, with the 10 panel directly adjacent to the panel under consideration. The characteristics of the invention enable each panel to be bonded with each of the adjacent panels by the concrete that is cast within it and into the gap arranged between the panels as a result of the presence 15 of the recesses. It should also be observed that the fastening duct makes it possible not only to obtain a single piece block of concrete at the foot of the panel, but also for casting to be performed very simply into only one of the 20 parallel circular cavities of the slab, The fastening duct allows still-liquid concrete to flow between the circular cavities and thus to fill the panel while using only one circular cavity for casting the concrete. With the fastening duct, the cylindrical cells are 25 bonded to one another. This limits cracking of the panel. The bottom, top, and side recesses thus provide a form of bonding between the cylindrical cells of two adjacent panels, Finally, an essential advantage of the monolithic 30 panel of the invention is its simplified method of fabrication as defined below. According to an advantageous characteristic of the invention, the fastening duct is situated at a distance of more than 3 cm from the bottom edge face (and thus the 35 bottom recess), According to this characteristic, the fastening duct is separated from the bottom recess by partitions between 11 the circular cavities. Material is thus present in the these partitions over a height of more than 3 cm, This thus serves to separate the function of providing a junction with the bottom panel that is 5 performed using the bottom recess, and the function of fastening and filling the circular cavities in a single step. According to a preferred characteristic, a said side bonding cavity is in alignment with the fastening duct at 10 each of its ends. The presence of such a side bonding cavity in alignment with the fastening duct makes it possible to obtain a monolithic block of concrete running not only within the panel between its two side edge faces, but 15 also over its sides and indeed in the adjacent panel This makes it possible to provide double retention at the bottom of the panel by means of a single piece of concrete situated generally horizontally above the single piece of concrete filling the bottom recess. 20 Nevertheless, it should be observed that in accordance with a preferred additional characteristic of the invention, a plurality of bonding openings are distributed along the side edge faces. Such a characteristic makes it possible to provide 25 stronger two-dimensional bonding of the panel in question with the adjacent panel side-by-side and with the adjacent panel below. Concrete is obtained in the form of a single piece having the shape of two combs, a horizontal comb on the bottom of the panel and a vertical 30 comb on the side of the panel, According to particular characteristic of the invention, the circular cavities are separated from the edge faces and from one another by a distance lying in the range 3 cm to the diameter of the circular cavities. 35 With such a characteristic, a particularly advantageous reduction in the weight of the panel is 12 ensured while also ensuring that the panel is suitably stiff, According to another particular characteristic of the invention, said fastening duct presents a section in 5 a longitudinal plane perpendicular to said transverse longitudinal midplane of the panel that is of area greater than or equal to the area of said circular section of the circular cavities in a transverse plane perpendicular to said midplane, 10 it can be understood that when said panel has its main faces placed vertically, the circular section of said circular cavities is a section in a plane that is horizontal, and the section of said fastening duct is a section in a vertical plane. 15 This characteristic makes it possible to ensure that concrete flows well between the circular cavities during filling, Advantageously, said transverse side bars project from said vertically-extending side margins delimiting 20 said recess, by a distance that is less than the depth of the side recess, said side bars being distributed, preferably regularly distributed, over the entire length of the panel in said longitudinal direction of the panel. More particularly, in order to comply with minimum 25 percentages of steel as defined in standards for reinforced concrete, said bars extending in said transverse direction present an accumulated sectional area of steel of at least 1,2 square centimeters per linear meter of the panel in the longitudinal direction 30 of the panel. Also advantageously, said steel bars embedded in the concrete comprise steel bars extending both in the longitudinal direction and in the transverse direction of the panel. 35 The invention also provides a method of fabricating a panel of the invention for constituting a permanent form for use in fabricating walls.

13 The method comprises the steps of: placing two "bottom" combs on a concrete casting surface on either side of a concrete casting plane, each bottom comb having the same number of semicircular 5 notches spaced apart from one another by an "interval" distance lying in the range 3 cm to twice the diameter of the notches; - placing a plurality of inflatable tubes above the casting plane between the two bottom combs and 10 perpendicularly relative thereto, the plurality of tubes being side by side, parallel to one another, and resting in the notches of the bottom combs; placing two "top" combs above the bottom combs and the tubes placed between them, the top combs having the 15 same number of semicircular notches separated from one another by the interval distance, the inflatable tubes then being installed in the notches of the combs, each set of top and bottom combs presenting a profile constituting the negative of the bottom edge face or the 20 top edge face; * placing metal reinforcing bars on the inflatable tubes; . placing optionally-permanent tube spacers for creating a fastening duct between the inflatable tubes, 25 the tube spacers being in alignment along a line perpendicular to the tubes; placing side edge face shuttering parallel to the tubes on either side of the plurality of tubes, the shuttering enabling the bars to project laterally from 30 the edge face shuttering and presenting in profile the negative of the side recesses; . placing at least one edge face spacer on either side of the future panel between the edge face shuttering and the nearest tube to provide a said bonding cavity; 35 . connecting a device for inflating the tubes to one end of the tubes; 14 inflating the tubes so that they block the spacers between the tubes and between the edge face shuttering and the nearest tube; casting concrete up to the top of the combs, 5 thereby covering the tubes and the spacers; waiting for the concrete to harden completely; extracting the inflatable tubes; removing the top combs; releasing the edge face shuttering; 10 separating the resulting panel-forming permanent form from the concrete casing plane; and extracting the spacers if they are not permanent. This method associated with the invention enables a panel of the invention to be fabricated in a manner that 15 is particularly fast and simple. It makes use of a principle of inflatable shuttering made up of a membrane made using a matrix of rubber reinforced by a textile (sometimes referred to as "mine fabric") that is inflated under pressure from injected 20 gas. The inflatable shuttering of the invention consists in a plurality of inflatable and expandable pipes that are closed at each end. This method makes it possible very easily to obtain circular cavities in the concrete and thus to fabricate 25 the permanent form of the invention, Nevertheless, the invention implies using particular elements for imparting the characteristics of the invention to the concrete slab with square section grooves. Thus, the features of the top and bottom combs and of the edge face shuttering make 30 it possible to ensure that these particular technical characteristics are present. Furthermore, the use of spacers between the various tubes of the inflatable shuttering enables the fastening duct to be made in particularly simple manner and enables 35 the side bonding openings to be made. It should be observed at this point that in the event of window or door type openings being needed in the 15 panel that is to be obtained, the tubes used should be shorter so as to stop either above or below the intended opening, In the particular circumstance of making a window, a monolithic wall portion is thus obtained either 5 above or below the opening. Nevertheless, the saving in weight for the panel remains advantageous when using the invention. Depending on the intended application, the tubes may be placed above or below the opening. Then the tubes are placed below the opening, they 10 have access to the fastening duct, thereby enabling them to be filled together with the other circular cavities. in contrast, when the tubes are placed above the opening, they cannot be filled from the fastening duct and the circular cavities need to be filled in 15 conventional manner from the top of the panel. Nevertheless, under such circumstances, specific spacers may be installed at the time of fabricating the panel so as t o enable such circular cavities situated above the fastening duct to communicate with the 20 neighboring circular cavities in order to avoid any need to fill the circular cavities located in this way above the opening in independent manner. It should also be observed that it is possible to perform a step of inserting recoverable cones, typically 25 having a diameter of 20 millimeters (mm) and a length equal to the thickness of the finished wall, before the step of casting concrete. This makes it possible to pass threaded rods for fastening stays once the cones have been removed from the form that is finally obtained. 30 Brief description of the drawings Other characteristics and advantages of the present invention appear from the following description made with reference to the accompanying drawings which show an 35 embodiment having no limiting character. in the figures: Figures !A and lB are respectively a perspective view of the top portion of a panel of the invention (the 16 circular sections of the circular cavities 10 appear flattened in the figure because of the optical effect of perspective), and a perspective view of the bottom portion of a panel of the invention also showing the 5 internal structures in dashed lines, Figures 2A to 2H show the conduct of the method of the invention in a section view taken in one of the circular cavities and parallel thereto. Figures 3A to 31 show the same method in a section 10 view taken between the circular cavities in a plane parallel thereto. Figures 4A to 4J show the conduct of the method of the invention in a section view taken on a plane perpendicular to the circular cavities of the panel that 15 is finally obtained. Figures 5A to SE are respective face views of the bottom and top combs, a face view of two combs assembled together, and two section views showing the top and bottom combs that are located at the top and the bottom 20 of the panel, the first section being taken in a circular cavity and the second between the circular cavities. Figures 6A to 6D show a preferred embodiment of tube spacers used between the tubes enabling circular cavities to be made in the method of the invention. 25 Figure 7 shows a particularly advantageous example of edge face shuttering. Figures 8A to 8C show a first stage in laying a panel of the invention side to side with another panel of the invention. 30 Figures 9A to 9C show the second stage of this laying method. Figure 10A to 10C show the third stage of this laying method, prior to casting concrete in and between the two panels. 3S Detailed description of an embodiment Figure 1A shows a panel 1 of the invention including 17 a plurality of circular cavities 10 arranged in parallel and extending in the vertical longitudinal direction of the panel between a top edge face AS and a bottom edge face Al visible in Figure 1B, the cavities being 5 regularly spaced apart in the transverse direction of the panel perpendicular to the long tudinal direct ion The top edge face AS presents a recess ES along its entire length, The top edge face AS is asymmetrical and the top recess ES is formed along the entire length of the top 10 edge face which is asymmetrical, This asymmetry defines a "support" top margin SAS and a "retention" top margin referenced FR. This retention margin FR serves as permanent shuttering for stopping the concrete while the concrete is being cast for securing the floor with the 15 wall. The margins FR may be provided with the ribs in association with the circular cavities 10 in order to stiffen them. The panel 1 also has vertical side edge faces referenced PL, each presenting a recess EL along its 20 entire length. Because of the presence of the recess EL, each side edge face RL thus presents two side margins SAL visible in Figures lA and 1B. The side junction bars referenced A' project level with the side edge faces RL. Said transverse side bars (A') are arranged between the 25 side margins and they project in the transverse direction out from the panel, the distance over which they project being less than the depth of the side recesses, said side oars being distributed, preferably regularly distributed, along the entire height of the panel. 30 Figure 1B shows the foot of the panel I of the invention. In this figure, the bottom edge face AI is visible. It presents a bottom recess EI over its entire length into wh ch the circular cavities 10 open out. The recess EL defines two "bearing" margins SAA that are 35 symmetrical about a vertical and transverse midplane of the pane> In addition, it should be observed that the panel 1 includes a fastening duct referenced 11 and shown 18 in dashed lines, This duct 11 connects with all of the circular cavities 10 above the recess El. It is advantageously oblong in section in a (vertical) longitudinal plane perpendicular to said transverse and 5 longitudinal midplane of the panel, being of width lying in the range 3/4 of the diameter of the circular cavities 10 to said diameter. In this example it presents a section of area lying in the range 2 to 4 times the area of the section of a circular cavity 10. 10 it should be observed most particularly that the fastening duct 11 in this example is separated from the bottom recess EI. Advantageously, this separation distance is greater than 3 cm so as to ensure that the section of the concrete present between the fastening 15 duct and the recess can deliver sufficient strength to oppose the traction force induced by the maximum hydrostatic pressure of concrete at the foot of the wall. In addition, the panel 1 includes a transverse bonding cavity 12 between the circular cavity 10 closest 20 to the side and an opening in the side edge face RL. It should be observed that in the embodiment shown, the side bonding cavity 12 is in alignment with the fastening duct 11. This characteristic is advantageous, since under such circumstances, when filling the two side panels, it 25 is ensured that the concrete matrix is continuous so as to provide a monolithic junction between the two fastening ducts of two adjacent panels. in the embodiment of Figure 1, it can be seen that a single bonding opening and cavity is provided. 30 Nevertheless, it is advantageous to provide a plurality of bonding openings and cavities over the entire length of the side edge face, these bonding openings and cavities being distributed at regular spacing along the height of the panel. This enables the gaps between the 35 panels to be filled with concrete at a plurality of points. This leads to a single piece of concrete of comb shape that provides very good bonding between two panels.

19 Finally, in the embodimerit of Figure 1B, it should be observed that the fastening duct 11 presents a section in a longitudinal plane perpendicular to said midpiane of the panel that is of area greater than the area of the circular section in a horizontal plane of a circular cavity. Such a characteristic enables the concrete to flow well during filling via a single circular cavity LnLo the fastening duct 11. Advantageously, the thickness of the concrete is 10 greater than 4 cm between the circular cavities 10 and the outside of the panel 1. The panel typically presents thickness lving in the range 15 cm to 100 cm, and preferably in the range 16 cm to 30 cm, the diameter of the circular cavities lying in the range 7 cm to 27 cm, 15 A panel in a particularly advantageous embodiment presents a thickness of 20 cm, circular cavities 10 having a diameter of 12 cm that are spaced apart from the side edge faces by 5 cm and between one another by 4 cm. The recess advantageously presents a depth of the order 20 of about ten centimeters. The fastening duct 11 is advantageously situated about ten centimeters from the bearing margins SAA of the panel I. Figures 2, 3, and 4 show the steps of the method of the invention respectively in three different section 25 views. The first view, shown in Figure 2, is taken in a circular cavity 10 In parallel therewith. The second view, shown in Figure 3, is taken between the circular cavities, and parallel thewith. The third view, shown in Figure 4, is taken in a pLane perpendicular to the 30 circular cavities. The first step of the method shown in Figures 2A and 3A consists in placing two "bottom" combs PI and PiS that extends parallel in a said transverse direction of the panel that is to be made, on either side of a casting 35 plane PC. The profile face view of a bottom comb Pi is shown in Figure SA. The combs PiT and PiS thus include a plurality of notches Ei distributed along the comb. The 2L0 notches Ei present an internal section outline of semicircular shape suitable for receiving and holding the tubes 2 at both of their longitudinal ends. It should be observed that the "bottom" combs PiS and PI are 5 advantageously spaced apart in the longitudinal direction so that their respective notches Ei can respectively support of the ends of the tubes 2. The notches Ei are spaced apart from one another in the transverse direction by a distance lying in the range 3 cm and the diameter of 10 the notches. A thickness of 3 cm constitutes a limit for enabling concrete to be cast correctly and for obtaining sufficient tear-out strength. The spacing between the tubes may be up to twice their diameter, Nevertheless, the advantage of the invention would then be reduced 15 since the panel would be only a little lighter. The combs PiS and PiI also have a side recess profile PEL at their transverse ends on either side of the notches Ei, In a second step shown in Figures 2B and B, a plurality of inflatable tubes 2 are placed above the 20 casting plane PC between the two bottom combs PiI and PiSM Figures 2B and 3B also show the third step of the invention in diagrammatic manner, which step consists in placing the "top" combs PsI and PsS including 25 semicircular notches Es above the tubes 2, themselves placed in the bottom combs Pi! and PiS. Figure 51 gives a profile face view of a comb Ps. In this figure the notches face downwards as does the side recess profile PEL. The notches Es are spaced apart 30 at distances identical to those spacing apart the notches Ei of the bottom combs Pi. Figure 5C is a face view showing the combs Pi and Ps as assembled together as a result of the steps performed in Figures 2B and 3B. 35 Figures SD and SE show the specific profiles in cross-section of the bottom and top combs. The bottom and top combs Pil and Psi arranged at the bottom of the panel and the bottom and top combs PiS and PsS arranged at the top of the panel have different transverse profiles. Figures 5D and SE are two section views, Figure 5D 5 being taken through the notches Ei and Es, and Figure 5E being taken between these notches. in both of these figures, the combs Pit and PsI for placi ng on the bottom of the panel present bottom recess profiles PEI. 10 Top recess profiles PES appear on the combs PiS and PsS that are to be placed on the top of the panel, with these profiles being negatives of the recesses as finally obtained on the panels of the invention. Figure 4A shows a step of the method of the 15 invention that is not shown in Figures 2 and 3 and that consists in incorporating reinforcing bars A arranged perpendicularryto the tubes 2 so as to give the panel the ability to withstand horizontal shrinkage of the concrete, where that shrinkage is .he greatest. It 20 should be observed at this point that two-directional reinforCement, in particular in the form of a mesh extending in both the longitudinal and the transverse directions could equally well be used. Under such circumstances, the bars should be installed 25 perpendicularly and in parallel relative to the tubes 2. Where necessary, prestress bars could in particular be installed at this stage of the method of the invention. After casting the concrete, the steel reinforcing bars A are arranged at about 3 cm from the nearer main outside 30 face of the panel Thereafter, the method of the invention presents a step of inserting tube spacers 3 that are interposed between the tubes 2 in a common transverse alignment close to the bottom ends of the panel in order to hold 35 the tubes Parallel to one another and enable a fastening duct to be created between the circular cavities that are 22 to be created by the presence of the inflatable tubes, This step is shown in Figures 2C, 3C, and 4B. Advantageously, the tube spacers 3 are not permanent and they are recovered after thermal maturation of the 5 concrete of the resulting panel 1. An embodiment of such a tube spacer 3 is shown in Figures 6A to 6D. For this purpose, the tube spacers 3 are advantageously made of a flexible resin having a central opening 30, as can be seen in Figure 6A. This enables them to be extracted 10 after the panel has hardened. As shown in Figures 6A to 6D, the tube spacers 3 are shaped so as to fit closely to the shape of the tubes 2 once inflated. Their width, written "W", in the transverse direction advantageously lies in between the 15 diameter of the tubes before inflation and the diameter of the tubes after inflation. This is shown in Figures 4B and 4C. It should be observed at this point that the steps of putting metal reinforcement into place and of putting 20 the tube spacers into place may be performed one after the other or vice versa, the order in which these steps are performed not being critical, Figure 4C shows the step of installing an edge face shuttering 4 beside the tubes. in an advantageous 25 embodiment, these edge face shutterings 4 have reinforcing bars A" that project sideways from the edge face shuttering 4 beyond the side margins by a distance that is less than the depth of the side recess so as to be capable of being received in the side recess of 30 another panel placed adjacently and with which a junction is to be made. By way of example, the reinforcing bars A' are installed on the edge face shuttering 4 beforehand and they are held by means of resin-based shutters serving both to hold them and to close the orifices 35 needed for installing the bars A' on the edge face shuttering 4 so as to prevent concrete from escaping through these orifices while casting.

23 Figure 7 shows such an edge face shuttering 4 carrying reinforcing bars A' - It is explained below that such an edge face shuttering structure 4 is advantageously deformable so as to enable it to be 5 extracted once the panel 1 has been fabricated. It should also be observed that the edge face shuttering 4 presents a lateral recess profile referenced PEL that runs on in continuity with the lateral recesses profile FEL of the combs Pi and Ps shown in Figures 5A and 5B. 11 Insofar as the edge face shuttering 4 is deformable, a spacer 4' is advantageously installed at one or more locations of the edge face shuttering, as shown in Figure 4D. This figure also shows the step of installing an 15 Hedge face" spacer 3' between the edge face shuttering 4 and the last side tube 2, as shown in Figure 4D. The edge face spacer 31 serves to obtain at least one fastening opening 12, and it can be seen at this point that a plurality of edge face spacers may 20 advantageously be installed along the edge face shuttering 4 and the tube 2 closest to the edge face shuttering 4. in a step 4E, the tubes are inflated so as to wmargin the edge face spacer 3' between the edge face 25 shuttering 4 and the tube closest to the side, and also wmargin the tube spacers 3 between the tubes 2, it should be observed at this point that inflating the tubes 2 may possibly be performed before installing the edge face spacer, which is then installed by force between the 30 edge face shuttering 4 and the tube closest to the side. It should be observed in general terms that the order in which the steps of the method are performed may be modified considerably without departing from the definition of the method of the invention, 35 The following steps shown in Figures 2D, 3D, and 4F shows the end of casting concrete and the begining of the maturing cycle. At the end of the thermal maturing 24 cycle, as shown in Figure 4G, the inflatable shuttering tubes 2 are deflated and then removed. The end of this step is shown in Figures 2E and 3E, Thereafter the head and foot combs are removed from 5 the panel 1, as shown in Figures 2F and 3F. The edge face shuttering is also removed after removing the spacer 4' shown in Figure 4G and then deforming the shuttering 4, as shown in Figure 4H, The resulting panel 1 as shown in Figures 2F, 2, 10 and 41 is thus ready for handling, as shown in Figures 2G, 3G, 2P, 39, and 4. Figure 3K shows an example of storing panels as obtained in this way, which panels can be handled while flat without any difficulty, unlike precast walls. 15 Finally, Figures 8, 9, and 10 show the method of laying a panel lb of the invention beside an adjacent panel la that has already been paid. in building methods, an margin or a floor is generally available that presents a plurality of starter 20 bars A" extending vertically waiting to start installing the storey above, These bars A" may be extracted from flooring, With the invention, it should also be observed that it is particularly simple to install such vertical bars on a panel of the invention, It suffices to place 25 metal bars vertically in the panel of the invention before casting concrete in the circular cavities. Once the concrete has been cast, these bars are fastened vertically on the top of the panel and they are ready for use in installing structures above. It can 30 thus be seen that the invention is of great advantage since it is completely modular and it simplifies numerous steps of construction, including those consisting in preparing a lower storey for installing a higher storey. In Figure SA, a new panel lb carrying side bars A' 35 is brought up to a previously installed panel wA. Figure 3B shows that the bars A" are situated outside the 2S panel lb and that their top ends are received in the bottom recess EI of the panel lb. It should be observed at this point that the side bars A' of the panels La and lb need to be spaced apart 5 by a height that is greater tnan or equal to the maximum expected height of the bars A" of the lower structures on which the Panels are to be inst called. This can be seen in Figure 10 that is described below. Once the panel lb has been brought up to the panel 10 la and is at a minimum height relative to the already installed bars A" so as to allow the Panel lb to slide sideways over there, as shown in Figure 8C, the panel lb is slid horizontally. Figure 9 shows the horizontal sliding of the panel 15 lb over the bars A" towards the panel la. It can be seen that the bars A' of the two panels la and lb the irnterpenetrate and overlap as shown in Figure 9C. This is pari cu larly advantageous, given that since the bars are arranged in the side recesses of the two panels la 20 and lb, this ensures that when concrete is cast into the recesses, the bars of each of the panels are complete l y secured to the other panel. In Figure 9B, it can be seen that the panel 1b is still situated above the bars A". Finally, in the third stage, shown in Figure 10, the 25 panel is slid downowards so as to cause the bars A" preinstalled on te existing structure to pen et ra te into the circular cavities 10 These circular cavities 1.0 can thus receive bars A" that will engage directly with the concrete when it is cast. It can be understood at this 30 point that in order to enable the panel lb to slide verically without the bars A' preventing such movement-, it is necessary for the bars A' to be situated at regular intervals that are greater than the greatest length expected for a bar A", 35 With the invention and the presence of side fastening openings in the panels, concrete is cast simultaneously into both panels la and lb. Casting 26 concrete also serves to provide fastening with the lower structure carrying the bars A", so construction thus takes place very quickly, while also providing very good strength for the wall as obtained in this way. 5 Finally, it should be observed that various embodiments can be provided in accordance with the principles of the invention.

Claims

1. A panel forming a monolithic block of concrete for constituting a permanent form for wall fabrication, the 5 panel presenting: - a plurality of circular section cylindrical cavities referred to as "circular cavities" that are mutually parallel and that extend in a longitudinal 10 direction of the panel between a "top" edge face and a "bottom" edge face of the panel, these circular cavities being distributed all along the panel between two side edge faces and spaced apart by a distance lying in the range 3 cm to twice the diameter of the circular cavities 15 in the transverse direction perpendicular to the longitudinal direction of the panel; - a fastening duct placed at the foot of the panel connecting together the circular cavities and extending 20 perpendicularly thereto, the fastening duct being for filling with concrete when the panel is used; - a bottom edge face forming a continuous "bottom" recess over its length in said transverse direction, 25 being delimited by two bottom "bearing" margins extending in said transverse direction and preferably arranged symmetrically relative to a transverse longitudinal midplane of the panel, the bottom recess being for filling with concrete when the panel is used as a 30 permanent form; - an asymmetric top edge face forming a continuous "top" recess extending over its entire length in said transverse direction between a "support" top margin 35 suitable for receiving and supporting a horizontal slab, and a "retention" top margin, the support and retention top margins extending along the length of the top edge 28 face in said transverse direction, said support top margin being at a height higher than said retention top margin, said retention margin being suitable for retaining concrete cast over said horizontal slab resting 5 on said support top margin; and - metal reinforcing bars incorporated in the concrete outside said circular cavities and said fastening duct, extending at least along the length of 10 the panel in said transverse direction of the panel; and - side edge faces each forming a side recess, each being delimited by two "side" margins, said side edge faces and said side margins extending in said longitudinal direction, preferably symmetrically relative 15 to a said transverse longitudinal midplane of the panel, each said side recess being continuous over the entire length of each said side edge face in the longitudinal direction of the panel, each side recess being for filling with concrete when joining the panel with a side 20 edge face of another panel while fabricating a wall, side bars projecting from said side edge faces extending outside the panel in said transverse direction of the panel; and - at least one "bonding" side cavity in each side 25 edge face extending in said transverse direction between an opening in each side edge face and the nearest circular cavity.

2. A panel according to claim 1, wherein it has a single 30 said fastening duct.

3. A panel according to claim 1 or claim 2, wherein said fastening duct is situated at a distance of more than 3 cm from the bottom edge face. 35 29

4. A panel according to any one of claims 1 to 3, wherein a said side bonding cavity is in alignment with the fastening duct at each of its ends.

5 5. A panel according to any preceding claim, wherein a plurality of said bonding cavities are distributed along said side edge faces.

6. A panel according to any preceding claim, wherein said 10 circular cavities are spaced apart from the side edge faces and spaced apart from one another by a distance lying in the range from 3 cm to the diameter of said circular cavities. 15

7. A panel according to any preceding claim, wherein said fastening duct presents a section in a longitudinal plane perpendicular to said transverse longitudinal midplane of the panel that is of area greater than or equal to the area of said circular section of said circular cavities 20 in a transverse plane perpendicular to said midplane.

8. A panel according to any preceding claim, wherein said transverse side bars project from said side margins delimiting said side recess, by a distance that is less 25 than the depth of the side recess, said side bars being distributed, preferably regularly distributed, over the entire length of the panel in said longitudinal direction of the panel. 30

9. A panel according to any preceding claim, wherein said bars extending in said transverse direction present a cumulative steel section area of at least 1.2 square centimeters (cm 2 ) per linear meter of the panel in the longitudinal direction of the panel. 35 30

10. A method of fabricating a panel for constituting a permanent form for fabricating walls according to any preceding claim, the method comprising the steps of: 5 - placing two "bottom" combs on a concrete casting surface on either side of a concrete casting plane, each bottom comb having the same number of semicircular notches spaced apart from one another by an "interval" distance lying in the range 3 cm to twice the diameter of 10 the notches; - placing a plurality of inflatable tubes above the casting plane between the two bottom combs and perpendicularly relative thereto, the plurality of tubes 15 being side by side, parallel to one another, and resting in the notches of the bottom combs; - placing two "top" combs above the bottom combs and the tubes placed between them, the top combs having 20 the same number of semicircular notches separated from one another by the interval distance, the inflatable tubes then being installed in the notches of the combs, each set of top and bottom combs presenting a profile constituting the negative of the bottom edge face or the 25 top edge face; - placing metal reinforcing bars on the inflatable tubes; 30 - placing tube spacers for creating a fastening duct between the inflatable tubes, the tube spacers being in alignment along a line perpendicular to the tubes; - placing side edge face shutterings parallel to the 35 tubes on either side of the plurality of tubes, the shutterings enabling the bars to project laterally from 31 the side edge face shuttering and presenting in profile the negative of the side recesses; - placing at least one edge face spacer between each 5 edge face shuttering and the nearest tube to provide a bonding cavity; - connecting a device for inflating the tubes to one end of the tubes; 10 - inflating the tubes so that they block the spacers between the tubes and between the edge face shuttering and the nearest tube; 15 - casting concrete up to the top of the combs, thereby covering the tubes and the spacers; - waiting for the concrete to harden completely; 20 extracting the inflatable tubes; - removing the top combs; - releasing the edge face shutterings; 25 - separating the resulting panel-forming permanent form from the concrete casing plane; and - extracting the spacers if they are not permanent. 30

11. A panel as claimed in any one of claims 1 to 9, wherein the circular cavities are regularly spaced apart in the transverse direction. 35

12. A method as claimed in claim 10 wherein the tube spacers are permanent.