Patent Publication Number: US-2022228379-A1

Title: Shuttering element and method for constructing a concrete structure in a cavity

Description:
TECHNICAL FIELD 
     The invention relates to a shuttering element and to a method for constructing a concrete structure in a cavity. 
     PRIOR ART 
     A conventional poured concrete structure intended to contain a liquid, and in particular a swimming pool, comprises on the one hand a concrete slab (which forms the bottom of the structure) and generally vertical walls. Given its intended purpose, such a structure must be perfectly watertight. 
     Conventionally, it is possible to ensure the watertightness of such a structure by applying thereto a polyvinyl chloride (PVC) tarpaulin known as a “liner.” A liner completely covers the faces of the structure, referred to as interior faces, oriented towards the interior of the structure, and is intended to be in contact with the liquid. 
     However, it is known that liners have a very low tear resistance, which necessitates their complete replacement in the event of damage. 
     In view of this prior art, the inventor has determined that it could be advantageous to have a method for constructing a concrete structure which is watertight ab initio and does not require the use of a liner to be watertight. 
     SUMMARY OF THE INVENTION 
     The invention aims to overcome this drawback. 
     Thus, the invention relates to a shuttering element. 
     The invention also relates to a method for constructing a concrete structure in a cavity. 
     To this end, the invention provides a shuttering element for the construction of a vertical wall of a concrete structure intended to contain a liquid. 
     The shuttering element has inner faces and outer faces which are oriented toward the interior and the exterior of the shuttering element, respectively. 
     The shuttering element comprises:
         a first shuttering panel made of perforated sheet metal,   a second shuttering panel made of fiber cement, and   spacers fixed to the inner faces to keep the shuttering panels parallel to each other and at a distance from each other.       

     Furthermore, the shuttering element comprises, at its lower end, a lower opening made in one of the outer faces, referred to as the first outer face, and through which the concrete may flow when the shuttering element is installed in the vertical position. 
     In addition to the features mentioned in the preceding paragraphs, the shuttering element may have one or more of the following additional features, considered individually or according to the possible technical combinations. 
     In one particular embodiment, the lower opening extends over the entire width of the first outer face. 
     In another particular embodiment, the spacers are articulated between a folded transport position, in which the inner faces are held against each other, and a deployed position of use, in which the inner faces are parallel to each other and at a distance from each other. 
     According to a particular embodiment, the inner faces each comprise a plurality of stiffeners, in which the plurality of spacers are fitted. 
     According to another particular embodiment, the shuttering element further comprises
         at its upper end, an upper opening made in the other one of the outer faces, referred to as the second outer face, and   a third panel made of perforated sheet metal, which is folded at least in two parts, referred to as the first part and the second part, the first part and the second part each comprising an inner face and an outer face.       

     Furthermore, the third panel is fixed on the second outer face so that the outer faces of the first part and of the second part are oriented toward the outside of the shuttering element and in such a way as to:
         hold the inner face of the first part substantially below the upper opening, and   arrange the second part substantially at the level of the upper opening to form a predetermined acute angle between the inner face of the second part and a plane containing the upper opening.       

     Preferably, the upper opening extends over all or part of the width of the second outer face. 
     According to one embodiment, the shuttering element further comprises a plurality of horizontal stiffeners fixed on the upper leveling of the second outer face and on at least one side of the second part. 
     The invention also provides a method for constructing a concrete structure in a cavity, the structure being intended to contain a liquid. 
     The method according to the invention comprises the following steps:
         providing a plurality of shuttering elements according to the above embodiments,   vertically juxtaposing the plurality of shuttering elements on a bottom surface of the cavity, so as to orient the first openings toward the interior of the cavity,   arranging first reinforcements inside the plurality of shuttering elements,   arranging second reinforcements on the bottom surface of the cavity, so as to insert all or part of the ends of the second reinforcements in the lower openings,   first pouring fresh concrete inside the plurality of shuttering elements, in order to form the walls of the structure, and   then pouring fresh concrete on the bottom surface of the cavity, in order to form the concrete slab, while the concrete inside the plurality of shuttering elements is still fresh.       

     In a particular embodiment, the method further comprises the following step, when the first outer faces of the plurality of shuttering elements are made of fiber cement:
         applying a first layer of a first watertight liquid membrane on the outer faces of each of the plurality of shuttering panels, so that the first liquid membrane forms a first watertight shell upon drying.       

     In another particular embodiment, the method further comprises the following step:
         applying a second layer of a second watertight liquid membrane on the first watertight shell, so that the second liquid membrane forms a second watertight shell upon drying.       

     According to a particular embodiment, the first liquid membrane and the second liquid membrane are applied in crossed layers. 
     According to another particular embodiment, the first watertight liquid membrane is different from the second watertight liquid membrane. 
     According to yet another particular embodiment, a finishing covering is applied to the first watertight shell or to the second watertight shell. 
     Other aims, features, and advantages of the invention will become apparent on reading the following description, which refers to the appended figures which represent preferred embodiments of the invention, which are provided solely by way of non-limiting examples. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a shuttering element according to the invention, in the installation position on a bottom surface of a cavity. 
         FIG. 2  shows the third shuttering panel of the shuttering element of  FIG. 1 . 
         FIG. 3  is a side view of the third shuttering panel of  FIG. 2 . 
         FIG. 4  shows the shuttering panel of  FIG. 2  when installed on the shuttering element of  FIG. 1 . 
         FIG. 5  shows the arrangement of  FIG. 4  with the attachment of stiffeners on the upper leveling of the shuttering element. 
         FIG. 6  shows the arrangement of  FIG. 4  with the attachment of stiffeners on the third shuttering panel of  FIG. 2 . 
         FIG. 7  shows a method for constructing a concrete structure in a cavity. 
         FIG. 8  shows a conventional arrangement of a curbstone on a wall for a liquid containment pool. 
         FIG. 9  shows a conventional arrangement of a curbstone on a wall for a liquid containment pool obtained according to an embodiment of the invention. 
     
    
    
     The figures do not necessarily respect the scales, particularly in terms of thickness, and are for illustrative purposes. 
     DESCRIPTION OF THE EMBODIMENTS 
     The shuttering element according to the invention is intended for the construction of a vertical wall of a concrete structure intended to contain a liquid. 
     In one example, the structure is a swimming pool, and the liquid is water. However, the invention also covers any liquid containment pool and any liquid suitable for being contained in the liquid containment pool. 
     In the rest of the description, the terms “upper,” “lower,” “top” and “bottom” refer to the arrangement of the shuttering element in the figures, which generally corresponds to its installation arrangement on a bottom surface of a cavity. The term “bottom surface” is understood to mean the bottom of the cavity which is generally flat and horizontal. 
     In general, the shuttering element is designed to be installed in a vertical position. In addition, it has inner faces and outer faces which are oriented toward the interior and the exterior of the shuttering element, respectively. Furthermore, the shuttering element is configured to allow the concrete to be poured into its interior from its upper part. 
     In  FIG. 1 , the shuttering element  100  comprises a first shuttering panel  110 , a second shuttering panel  120 , and a plurality of spacers  130 . 
     In the example of  FIG. 1 , the first shuttering panel  110  is made of perforated sheet metal. 
     In another example, the first shuttering panel  110  is of the same type as those marketed under the brand Metal Deploye, namely, a sheet perforated by multiple, staggered incisions in a metal sheet, then stretched to open those incisions. 
     In this example, the shuttering panel  110  may have openings less than or equal to 16 mm by 7 mm for a thickness greater than or equal to 1 mm, or have openings less than or equal to 28 mm by 9 mm for a thickness greater than or equal to 1.5 mm. However, the invention also covers other dimensions without requiring modifications to the principles of the invention. 
     In a particular embodiment, the first shuttering panel  110  has an inner face and an outer face which are oriented toward the interior and the exterior of the shuttering element  100 , respectively. Thus, the inner face and the outer face of the first shuttering panel  110  correspond to one of the inner and outer faces of the shuttering element  100 , respectively. 
     In another particular embodiment, the first shuttering panel  110  is made of galvanized steel to protect the steel against oxidation. 
     The first shuttering panel  110  thus configured allows the concrete to spread and to leak through the openings slightly so as to limit the thrust forces experienced by the second shuttering panel  120 . 
     In the example of  FIG. 1 , the second shuttering panel  120  is made of fiber cement, namely a prefabricated material consisting of very fine fibers agglomerated by a cement binder. 
     This material is advantageous because it is resistant to water and is unaffected by the moisture and laitance provided by the concrete poured during the construction of the structure, nor subsequently by the liquid contained in the structure. Moreover, with the construction process that will be described below, it will be shown that this material does not need to be covered with a finishing covering, such as polyvinyl chloride (PVC) tarpaulins known as “liners,” to make the structure watertight. 
     In one example, the second shuttering panel  120  is of the same type as those marketed under the brand Fibrociment and has a thickness of approximately 1 cm. However, the invention also covers other types of products and other dimensions without requiring modifications of the principles of the invention. 
     In a particular embodiment, the second shuttering panel  120  has an inner face and an outer face which are oriented toward the interior and the exterior of the shuttering element  100 , respectively. Thus, the inner face and the outer face of the second shuttering panel  120  correspond to one of the inner and outer faces of the shuttering element  100 , respectively. 
     In practice, the outer face of the second shuttering panel  120  is solid, flat, and smooth, which is not necessarily the case for the inner face of the second shuttering panel  120 . 
     In the example of  FIG. 1 , spacers  130  are fixed to the inner faces of the shuttering element  100  to keep the first shuttering panel  110  and the second shuttering panel  120  parallel to each other and at a distance from each other. 
     In one example, the spacers  130  have a thickness of at least 15 cm to ensure the watertightness of the structure. However, the invention also covers other dimensions without requiring modifications to the principles of the invention. 
     In a particular embodiment, the spacers  130  are articulated between a folded transport position in which the inner faces of the shuttering element  100  are held against each other and a deployed position of use in which the inner faces of the shuttering element  100  are parallel and at a distance from each other. 
     In this embodiment, an articulation mechanism of a known type may be used. 
     In another particular embodiment, the spacers  130  comprise anchor heads for fitting in the stiffeners  103 . 
     In this particular embodiment, the inner faces of the shuttering element  100  each comprise a plurality of stiffeners  103  in which the anchor heads of the plurality of spacers  130  are fitted. 
     In one example, the stiffeners  103  are formed by galvanized steel rails whereby they have a U-shaped cross section. The stiffeners  103  comprise a core, two wings which extend along the side edges of the core, and two wing returns which extend the wings so that the wing returns extend in a plane parallel to the plane of the core. 
     In this example, the stiffeners  103  are fixed to the inner faces of the shuttering element  100  by screws and are arranged so as to extend vertically when the shuttering element  100  is in the installation position. 
     The stiffeners  103  have a predetermined length whereby they project from the bottom of the first shuttering panel  110  or from the second shuttering panel  120  and delimit a lower opening  101 , through which the concrete may pass. 
     In other words, the shuttering element  100  comprises at its lower end, the lower opening  101 , which is made in one of its outer faces, referred to as the first outer face, and through which the concrete may flow. 
     In one example, the lower opening  101  extends over the entire width of the first outer face. 
     This arrangement has the effect of making the shuttering element  110  reversible, in particular in its use in the construction process which will be described below. Thus, the shuttering element may be oriented in any desired direction, as long as the lower opening  101  is at the bottom of the shuttering element  100 . 
     In a first example, the first outer face corresponds to the outer face of the first shuttering panel  110 . This configuration makes it possible to obtain a wall with a good metallic grip which is suitable for certain types of coverings. These are, for example, coverings such as undercoats (conventional mortar) or finishing coats applied in thickness (for example, approximately 2.5 cm). 
     On the other hand, in a second example, the first outer face corresponds to the outer face of the second shuttering panel  120 . This configuration makes it possible to obtain a wall suitable for all types of finishing covering such as liners, tiling, or paint. 
     In an optional embodiment, in view of the example of  FIG. 1 , the shuttering element  100  also comprises, at its upper end, an upper opening  102  made in the other of the outer faces of the shuttering element  100 , referred to as the second outer face. 
     Thus, due to the reversibility of the shuttering element  100 , if the lower opening  101  is made in the first shuttering panel  110 , then the upper opening  102  will be made in the second shuttering panel  120 . Conversely, if the lower opening  101  is made in the second shuttering panel  120 , then the upper opening  102  will be made in the first shuttering panel  110 . 
     In one example, the upper opening  102  extends over all or part of the width of the second outer face. For example, in  FIG. 1 , the upper opening  102  corresponds to a cutout of the second shuttering panel around the stiffeners  103 . 
     In this optional embodiment, the shuttering element  100  also comprises a third shuttering panel  140  made of perforated sheet metal of the same type as the first shuttering panel  110 . However, as illustrated in  FIG. 2 , the third shuttering panel  140  is substantially narrower than the first shuttering panel  110 . 
     In a particular embodiment, the width of the third shuttering panel  140  is less than approximately a third of the width of the first shuttering panel  110 , preferably less than half the width of the first shuttering panel  110 . 
     Furthermore, as illustrated in  FIG. 3 , the third shuttering panel  140  is folded at least in two parts, referred to as the first part  131  and second part  132 . The first part  131  and the second part  132  each comprise an inner face and an outer face. 
     In this optional embodiment, as illustrated in  FIG. 4 , the third panel  140  is fixed orthogonally on the second outer face, so that the outer faces of the first part  131  and of the second part  132  are oriented toward the outside of the shuttering element  100 , so as to hold the inner face of the first part  131  substantially below the upper opening  102  and so as to arrange the second part  132  substantially at the level of the upper opening  102  to form a predetermined acute angle α between the inner face of the second part  132  and a plane containing the upper opening  102 . 
     In one example, the first part  131  is fixed on the second outer face with screws on the stiffeners  103  mounted on the first shuttering panel  110 . 
     In another example, the acute angle α is between approximately 0° and approximately 90°, preferably between approximately 30° and approximately 50°. 
     This optional embodiment has the effect of allowing the widening of the upper leveling of the concrete wall according to the desired dimension L so that it can support curbstones, often made of natural or reconstituted stone, without the risk of cracks and/or breakage. This wider upper leveling may be reinforced by the arrangement of reinforcements in the space created. 
     The perimeter of a liquid containment pool generally comprises curbstones which separate the pool from a terrace formed around the swimming pool. As illustrated in  FIG. 8 , in the prior art, a curbstone  300  rests partly on the upper leveling of a wall  400  of the liquid containment pool and partly on the backfill  500 , which is located on the side of the ground in place  600 , because the width of the curbstone  300  is greater than the width of the wall  400 . In effect, the width of a curbstone  300  is generally 25 to 35 cm, while the width of the wall  400  is of the order of 15 cm. However, over time, the backfill  500  collapses and the curbstone  300  is then cantilevered with the risk of cracking and/or breaking. Thus, as illustrated in  FIG. 9 , the solution according to the invention makes it possible to better support the curbstones of the type of curbstone  300 . 
     In an example of this optional embodiment, as illustrated in  FIGS. 5 and 6 , the shuttering element  100  further comprises a plurality of horizontal stiffeners  104  fixed on the upper leveling of the second outer face and to at least one side of the second part  131 . 
     In one example, the horizontal stiffeners  104  are fixed on the upper leveling of the second outer face and on one of the sides of the second part  131  with screws. For example, one of the sides of the second part  131  may be the upper side and/or a lateral side. 
     The invention also involves a method  200  for constructing a concrete structure in a cavity. 
     In one example, the cavity is an excavation made in the ground. 
     In another example, the cavity is a reservoir of an existing containment pool. This arrangement has the effect of allowing the renovation of the existing damaged containment pool without requiring excavation or the removal or dismantling of the existing containment pool. 
     In step  210 , referred to as the provision, a plurality of shuttering elements  100  are provided as described above. 
     In step  220 , referred to as the juxtaposition, the plurality of shuttering elements are juxtaposed vertically on a bottom surface of the cavity, so as to orient the first openings  101  toward the interior of the cavity. 
     In step  230 , referred to as the first arrangement, first reinforcements are arranged inside the plurality of shuttering elements  100 . 
     In step  240 , known as the second arrangement, second reinforcement are arranged on the bottom surface of the cavity, so as to insert all or part of the ends of the second reinforcements into the lower openings  101 . 
     The arrangement of the first reinforcements and of the second reinforcements is of the type known in the field of civil engineering. Furthermore, the two arrangements may be achieved at the same time. 
     In step  250 , referred to as the first pour, fresh concrete is poured first inside the plurality of shuttering elements  100  in order to form the walls of the structure. 
     Fresh concrete refers to the state of the concrete when it has not started its setting and hardening process. 
     The first pour has the effect that the concrete flows through the lower openings  101 . 
     In step  260 , referred to as the second pour, fresh concrete is then poured on the bottom surface of the cavity, in order to form the concrete slab, while the concrete inside the plurality of shuttering elements is still fresh. 
     The second pour has the effect that the concrete poured on the bottom surface mixes with the concrete which flows from the openings  101  to form a one-piece reinforced concrete structure which is dimensionally stable and is not likely to crack. 
     Conventionally, the concrete is pulled over the top face of the concrete slab to obtain a flat and smooth surface. 
     In one example, it is ensured that the concrete slab has a thickness of at least 15 cm to ensure the watertightness of the structure. However, the invention also covers other dimensions without requiring modifications to the principles of the invention. 
     In a particular embodiment, the method further comprises a step  270 , referred to as the first application, wherein, when the first outer faces of the plurality of shuttering elements  100  are made of fiber cement, a first layer of a first watertight liquid membrane is applied to the outer faces of each of the plurality of shuttering panels  100 , so that the first liquid membrane forms a first watertight shell upon drying. 
     In this particular embodiment, the method further comprises a step  280 , referred to as the second application, in which a second layer of a second watertight liquid membrane is applied to the first watertight shell, so that the second liquid membrane forms a second watertight shell upon drying. 
     In one example, the first liquid membrane and the second liquid membrane are applied in crossed layers, namely, alternately in one direction and then in a perpendicular direction. 
     The application of a liquid membrane strengthens the watertightness of the structure since it adheres to the fiber cement material, blocking all or some of the pores of the material. 
     The cross-layered application is suitable for allowing the longitudinal and transverse placement of the fibers of the second shuttering panel  120 . 
     In another example, the first watertight liquid membrane is different from the second watertight liquid membrane. 
     The structure thus obtained may be used as is without the application of a liner, since it is watertight ab initio. 
     Indeed, the combination of a concrete veil, a fiber cement panel and a liquid membrane prevents the migration of water from the exterior of the structure to its interior. This migration water is generally rainwater which migrates into the backfill that surrounds the structure. This migration phenomenon corresponds to more than 50% of accidents involving water containment pools. However, the use of a liner as a watertight system does not make it possible to protect against this phenomenon. On the contrary, in this case, unsightly water pockets tend to form. 
     Furthermore, with the structure according to the invention, the water filling is immediate, unlike the structures which require the use of a liner, for which the liner must first be manufactured in the factory according to the measurements of the structure. 
     In yet another example, a finishing covering is applied to the first watertight shell or to the second watertight shell, such as liners, tiling, or paint. In this way, the structure according to the invention is scalable, because any finishing covering can be applied later. For example, it can be applied years after applying the liquid membrane.