FR2891562A1 - Prefabricated concrete unit for forming e.g. passage slab, has reinforcing sheet with connecting elements each being cut and folded to present anchoring faces, where elements are inclined with respect to sheet and extended inside body - Google Patents

Abstract

The unit has a concrete body comprising a reinforcing face opposed to a circulation or passage face, and a reinforcing sheet (5) integrated to the reinforcing face. The sheet has connecting elements each being cut and folded to present two main anchoring faces, where the connecting elements are drowned into the body. The connecting elements are inclined with respect to the sheet and extended inside the body at a distance from the sheet.

Description

The present invention relates to the technical field of concrete elements

  prefabricated or manufactured in situ, used to make accessories for covering road elements or, for example, but not exclusively, structural elements.

  In the above field, it is known to manufacture concrete slabs used in combination with pads to achieve a protective surface and circulation on the roof terraces for example.

  Such slabs must then have a very high resistance to bending, insofar as the latter are simply held by their four corners on four studs, the central portion of the slab receiving no support.

  Thus, it is not uncommon, in order to obtain sufficient strength and compatible with the safety standards in force, to produce slabs having a mass of the order of 30 kg for a square-shaped useful surface of 50 cm. side.

  However, if such slabs effectively make pavements with satisfactory strength characteristics, their weight make them particularly tedious to implement, a disadvantage that can be prohibitive as it is increasingly difficult to find personnel agreeing to ensure manual handling of such slabs.

  Thus, it has emerged the need to have a new type of concrete element allowing, for example, to produce slabs having a lower weight for mechanical strength characteristics at least equivalent to those of slabs according to the art. prior.

  In order to achieve this objective, the invention relates to a concrete element comprising a concrete body, one face of which is provided with a metal sheet of plane reinforcement. According to the invention, the concrete element is characterized in that: - the concrete body forms a circulation slab having a traffic face and, on the opposite side, a reinforcing face at which the reinforcing sheet is located - and the reinforcing sheet comprises connecting elements embedded in the concrete body, each connecting element being cut from the reinforcing sheet and folded to present two main anchoring faces, at least a part of which is inclined relative to to the reinforcing sheet and extends inside the concrete body away from the reinforcing sheet.

  It should be noted that according to the invention the main anchoring faces of the connecting elements form continuous surfaces with the two large faces of the reinforcing sheet.

  According to the invention, the reinforcing sheet is then flush with the surface of the corresponding face of the body or, on the contrary, is projecting relative to this corresponding face of the concrete body, without however being completely embedded or embedded in the concrete.

  The implementation of such a reinforcing sheet makes it possible to increase, very significantly, the tensile or flexural strength of the concrete element.

  Thus, it has been possible to observe a greater resistance to fracture and, above all, an increase in the crack resistance of a concrete element according to the invention, constituting a road slab, with respect to the mechanical characteristics of the concrete. a concrete element of the same dimensions but having an internal reinforcement embedded to constitute what could be called a traditional reinforced concrete.

  A concrete element according to the invention can be either made in the factory to form a prefabricated concrete element, or made to cast in situ at the time of implementation.

  According to the invention, the reinforcing sheet may be made of any suitable metal and, preferably but not exclusively, galvanized or galvanized steel sheet.

  According to the invention, the connecting elements may have different shapes or conformations. Thus, according to one embodiment of the invention, each connecting element is cut in the reinforcing sheet and stamped to have a generally frustoconical general shape converging towards the interior of the concrete block.

  According to another form of each connecting element is cut in the reinforcing sheet and stamped to have a generally pyramidal truncated general shape converging towards the interior of the concrete block.

  According to yet another embodiment, each connecting element comprises a series of substantially triangular teeth cut in the reinforcing sheet being arranged in a circle and folded to extend inwardly of the concrete block converging in the same direction . Thus, the series of teeth of each connecting element defines a kind of truncated cone.

  In the context of this embodiment and according to a characteristic of the invention, the anchoring teeth are arranged around a circular opening having a diameter of between 20 mm and 40 mm.

  According to another embodiment of the invention, each connecting element comprises a series of substantially triangular teeth cut in the reinforcing sheet being arranged in a polygon and folded to extend towards the interior of the concrete block while converging in the same direction. Each set of teeth then defines a kind of pyramid trunk.

  According to another characteristic of the invention and when the connecting elements are defined by teeth, some of the teeth may be twisted or deformed locally to increase their anchoring in the concrete.

  According to yet another characteristic of the invention, each connecting element comprises between 4 and 8 anchor teeth. It has indeed been found that these numbers of teeth offer good compromise between the individual strength of each large and the anchoring surface in the concrete.

  According to yet another characteristic of the invention, the connecting means are staggered on the reinforcing sheet. This advantageous characteristic of the invention makes it possible to obtain a homogeneous distribution of the connecting elements while preserving the mechanical strength of the reinforcing sheet.

  Of course the various features of the invention can be combined with each other in different combinations, insofar as they are not incompatible.

  Furthermore, various other features of the invention appear from the following description made with reference to the accompanying drawings which illustrate a preferred, but not limiting, embodiment of a prefabricated element according to the invention.

  Fig. 1 is a schematic perspective of a concrete element according to the invention, forming a slab of circulation.

  Fig. 2 is a partial section, according to the plane II-II of FIG. 1.

  Fig. 3 is a partial perspective of a reinforcing sheet constituting the concrete element illustrated in FIG. 1.

  Fig. 4 is a schematic perspective of a mold for the manufacture of the concrete element according to the invention, as illustrated in FIG. 1.

  Figs. 5 and 6 illustrate steps of a method of manufacturing the concrete element according to FIG. 1.

  A concrete element according to the invention is, for example, likely to constitute a slab passage or road, as illustrated in FIG. 1 and designated as a whole by the reference 1. Of course, this is only a preferred example of application of the concrete element according to the invention which can also be made to form for example, a gutter or, still, a beam for the realization of prefabricated floors or, still, any other functional and / or decorative element of the concrete.

  As is apparent from FIG. 1, the element 1 comprises a concrete body 2 which has, according to the illustrated example, a parallelepipedal general shape. The body 2 then comprises a passage or circulation face 3 and, opposite this circulation face 3, a face 4 which will be said reinforcement, at which is placed a sheet of reinforcing material which is secured of the reinforcing face 4 According to the invention, the reinforcing sheet 5 may be made of any suitable material. According to the illustrated example, the sheet 5 is made of a metal blank treated against corrosion, such as galvanized steel. Of course, it could be envisaged to implement another type of anticorrosive treatment or a blank of stainless steel.

  In order to ensure a connection between the reinforcing sheet 5 and the concrete body 2, the invention also provides for the use of means or connecting elements 10. According to the invention, these connecting elements 10 are obtained by plucking -drawing or cutting and folding the reinforcing sheet 5. According to the illustrated example and as is more particularly apparent from FIG. 3, the connecting elements 10 are arranged in a staggered manner, being distributed substantially uniformly over the entire surface of the reinforcing sheet 5. According to the illustrated example, each connecting element 10 comprises a series of six triangular teeth 11 disposed in a circle or around a substantially circular opening having a diameter of between 20 mm and 40 mm. As is more particularly apparent from FIG. 1, the teeth 11 of each connecting element 10 are inclined relative to the sheet 5 to converge in the same direction and thus define a kind of truncated cone particularly favorable for anchoring the reinforcing sheet 5 in the concrete. It will be noticed that each anchor tooth has two main anchor faces each in the continuity of a large face of the reinforcing sheet. The main anchoring faces are inclined relative to the reinforcing sheet and extend inside the concrete body away from the large faces of the reinforcing sheet. In order to further increase this anchoring, it is possible to twist all or some of the teeth 11.

  The concrete element 1, thus constituted, is manufactured using a mold 15, as illustrated in FIG. 3, having at least one imprint 16 to the shape of the element to be produced.

  Furthermore, it is prepared a concrete load that can be of any suitable nature, depending in particular on the use of the prefabricated element 2, it being understood that the term concrete is used here in the broad sense to refer to cement mixtures (s), aggregates (sands and / or gravel and / or chippings) and water, as well as, optionally, various adjuvants. Such additives may have, for example but not exclusively, a plasticizing function, a decorative function or a retarding function or the like.

  The impression 16 of the mold 15 is then filled with concrete, as illustrated in FIG. 5, then, before setting and drying of the latter, the reinforcing sheet 5 is placed on the concrete load, so as to include the anchoring elements 11, as shown in FIG. 6.

  After setting the concrete, the concrete element according to the invention is removed from the mold.

  It could also be envisaged to manufacture the concrete element according to the invention by placing, first of all, the reinforcing sheet at the bottom of the cavity 16 of the upwardly pointing pins, then filling the impression. 16 of concrete.

  The concrete element 1 according to the invention, thus obtained, has the particular feature of having a very high resistance to bending or traction and, more particularly, a greater resistance to cracking than traditional reinforced concrete elements, in which the reinforcements are completely embedded in the concrete body.

  The invention allows, for example, square slabs of 50 cm square and having a weight of 14 kg which meets the standards of mechanical strength for slabs, said sealer, while without reinforcing sheet slab having the same General square shape of 50 cm side and respecting the same standards of mechanical strength has a mass of 28 kg. The invention therefore makes it possible, by incorporating on the surface of the concrete body of the reinforcing sheet, substantially reducing the mass of the concrete element to an equivalent mechanical strength, so that it is possible to obtain prefabricated elements or not that can be easily transported and reduce the amount of concrete implemented.

  In order to demonstrate this superiority of the mechanical characteristics of the invention, a series of comparative tests has been carried out. These tests were carried out using, for all the elements tested, the same concrete whose composition by weight is as follows: water 8.5% sand: 48.5%, gravel 27.5%, cement: 15.5%, plasticizer adjuvant and air-entraining agent: 1.1% by weight of cement. This concrete has a compressive strength of 35 MP at 7 days.

  It was then realized slabs of different thicknesses and dimensions according to the invention, but also slabs without reinforcement, with an embedded reinforcement formed by a steel mesh or with an embedded reinforcement formed by a lattice of carbon fibers.

  The results of these tests are presented in the table below which shows the values measured after 7 days of drying of the slabs tested.

  Side Thickness Weight Nature of Stress Load Load of Stress (mm) (mm) (kg) reinforcement cracking rupture cracking rupture (daN) (daN) (MPa) (MPa) 210 25 2.6 None 310 310 7.3 7.3 210 25 2, 5 mesh 330 845 7.7 19.9 steel drilled 210 25 2.5 mesh 500 1310 11.7 30.7 carbon drilled 210 25 2.5 sheet 2 110 2 480 49.4 58, 1 according to the invention 400 25 9.3 None 309 309 7.3 7.3 Side Thickness Weight Nature of the Stress Load Load of Stress of (mm) (mm) (kg) reinforcement cracking rupture cracking failure (daN) ( daN) (MPa) (MPa) 400 25 9, 3 sheet 1800 2250 51 58.1 according to the invention 400 48 18 None 1120 1 120 7.2 7.2 500 25 14.6 None 312 312 7.4 7, 4,500 25 14,6 Mesh 370 1,080 8.8 25.7 Carbon Embedded 500 48 28 None 1140 1140 7.3 7.3 500 24 14 Sheet 1 700 2100 56.2 64.7 According to the invention It appears that the invention makes it possible, by incorporating the reinforcing sheet, to reduce substantially, at equivalent mechanical strength, the mass of the concrete element, so that it is possible to obtain prefabricated elements or not which can be easily transported and / or reduce the amount of concrete used.

  Of course, the invention is not limited to the above examples and, in particular, the realization of slabs, and various modifications can be made without departing from its scope.

Claims (9)

  1 - Concrete element comprising a concrete body (2), one side of which is provided with a metal sheet of plane reinforcement (5), characterized in that: - the concrete body forms a slab of circulation having a traffic face ( 3) and, in contrast, a reinforcing face (4) at which the reinforcing sheet (5) is located - and the reinforcing sheet comprises connecting elements embedded in the concrete body, each element of link (10) being cut from the reinforcing sheet and folded to present two main anchoring faces at least a portion of which is inclined relative to the reinforcing sheet and extends inside the concrete body at a distance of the reinforcement sheet.   2 - prefabricated element according to claim 1, characterized in that each connecting element (10) is cut in the reinforcing sheet and stamped to have a generally frustoconical general shape converging towards the interior of the concrete block.   3 - prefabricated element according to claim 1, characterized in that each connecting element (10) is cut in the reinforcing sheet and stamped to have a generally pyramidal truncated general shape towards the interior of the concrete body (2).   4 - prefabricated element according to claim 1, characterized in that each connecting element (10) comprises a series of teeth (11) substantially triangular cut in the reinforcing sheet (5) being arranged in a circle and folded to extend towards the inside of the concrete body (2) converging in the same direction.   5 - prefabricated element according to claim 4, characterized in that the anchoring teeth (11) are arranged around a circular opening having a diameter of between 20 mm and 40 mm.   6 - prefabricated element according to claim 1, characterized in that each connecting element (10) comprises a series of teeth (11) substantially triangular cut in the reinforcing sheet being arranged in a polygon and folded to extend towards the interior of the concrete body (2) converging in the same direction.   7 - prefabricated element according to one of claims 4 to 6, characterized in that some of the teeth (11) are twisted or deformed locally to increase their anchoring in the concrete.   8 - prefabricated element according to one of claims 4 to 7, characterized in that each connecting element (10) comprises between 4 and 8 anchor teeth.   9 - prefabricated element according to one of claims 1 to 8, characterized in that the connecting elements (10) are arranged staggered on the reinforcing sheet (5).