DESCRIPTION

The present patent relates to disposable formworks for the building construction industry and particularly it concerns a novel type of self- supporting disposable formwork made of a foam material with a metal stiffening reinforcement, for use in making reinforced concrete floors and ceilings in general.

There are known types of formwork for making concrete floors, which may be of the reusable or of the disposable type.

Known types of disposable formwork commonly consist of elements made of polystyrene foam in a generically parallelepiped shape, the lateral or upper surfaces of which contain longitudinal seats in which the reinforced concrete floor beams are made with corresponding metal reinforcement bars.

There are known disposable forms for making floors that comprise two half- forms made side by side so as to obtain a whole form by juxtaposing two half-forms.

The known disposable formwork is typically of modular width, corresponding to the distance between centres of the floor joists, e.g. approximately 600 mm, and long enough to cover the span or section of floor, which is generally of the order of several metres.

Said disposable formwork is installed and placed directly on the joists or lintels, and it must be supported by a temporary structure in order to provide a flat surface at a given elevation, on which the concrete floor can then be cast.

Said disposable formwork has the advantage of being much lighter than the known concrete slabs, or the known ribs with hollow bricks, and it is consequently easier to transport and also easier to handle and place in position.

On the other hand, using said disposable formwork makes it necessary to provisionally install intermediate supporting structures, that must remain in place for various days, preferably until the concrete has set completely. Known types of self-supporting formwork additionally comprise one or more metal reinforcement structures or sheets, embedded and/or arranged longitudinally inside the polystyrene foam body.

Said metal reinforcement structure serves the purpose of supporting not only the self weight of the formwork when installed, but also and more importantly the weight of the reinforcement bars, of the cast concrete and of the workers preparing the ribbed floor.

One advantage offered by the use of the known disposable formwork lies in that the foam material used to make said formwork has excellent thermal and acoustic insulation properties.

The known type of formwork also contains metal elements, integral with or embedded in the underside, designed to enable the subsequent attachment, with the aid of screws, of panels (made of plasterboard, for instance) for covering said underside, or of a metal mesh for the application of plaster coats.

To make the reinforcement structure for the floor beams, one or more main bars are placed inside seats provided in the disposable formwork.

Said reinforcement bars have to be inserted before casting the concrete and, on completion of the procedure to make the floor, they will consequently be positioned close to the bottom of the seat in the form.

As a result, the reinforcement bars may be incompletely covered with concrete, with consequent problems of bending in the load-bearing structures of the floor, i.e. in the ribbed floor beams.

There are known spacer elements, i.e. elements generically made of plastic that are placed adjacent to, or attached to the lower floor beam reinforcement bars before said reinforcement is placed inside the seat in the form. These spacer elements entail significant production costs and it takes time and manpower to position them adequately along the lower floor reinforcement bars inserted in each seat in the disposable formwork.

To overcome said drawbacks, a novel type of disposable formwork for making floors has been studied and developed which comprises at least one body or element made of foam material and at least one metal structure for stiffening purposes and for supporting the reinforcement bars in the floor beams.

One object of the present invention is to enable the proper placement of the main reinforcement bars in the floor beams exactly according to the requirements of the design calculations.

Another object of the present invention is to prevent said reinforcement bars from lying adjacent to the bottom of each seat in the formwork.

Another object of the present invention is to avoid the risk of said floor beam reinforcement bars lacking the concrete covering layer.

These and other direct and complementary objects are achieved by the novel disposable formwork for making floors that comprises a body or element made of foam material and at least one metal structure for stiffening purposes and for supporting the reinforcement bars in the floor beams.

The characteristics of the novel disposable formwork will be better clarified in the description that follows with reference to the drawings, that are attached as a non-limiting example.

Figure 1 shows a vertical cross-sectional view of the novel formwork.

Figure 2 shows an axonometric view of a metal stiffening and supporting structure (S).

Figure 3 shows a vertical cross-sectional view of a metal stiffening and supporting structure (S).

Figure 4 shows a vertical cross-sectional view of a metal stiffening and supporting structure (S) complete with the main floor beam reinforcement bars (F).

Figure 5 shows a view of the novel formwork with seats (El , E4) generically orthogonal to one another for containing the main bars (F, F') for reinforcing the floor crossbeams.

Figure 6 shows a cross-sectional view of a U-shaped metal element (S).

Figure 7 shows the same metal element (S) inserted in the body made of foam material (E) with a main reinforcement bar (F) lying thereon.

Figures 8 and 9 show an equivalent solution wherein the metal structure (S) comprises underlying U-shaped sheets of welded mesh.

The novel formwork comprises a body made of foam material (E) and at least one metal stiffening and supporting structure (S).

The body (E) of the novel formwork has a shape similar to that of the known forms, i.e. it is a parallelepiped with an elongated rectangular layout and a generically rectangular vertical cross-section, the upper surface of which comprises one or more concave seats (El) of dimensions suitable for creating the concrete ribbing on the underside of the floor and for containing the main bars (F) for reinforcing the concrete floor beams.

In this example, the main floor beam reinforcement bars (F) are shown merely for the purpose of illustrating the invention.

The lateral sides (E2) of the body (E) of the novel formwork may also contain seats and/or male-female coupling profiles for the connection of identical adjacent forms.

Each stiffening and supporting structure (S) comprises several generically U-shaped parallel bars (SI) and at least two longitudinal round bars (S2) for connecting and joining together said U-shaped bars (SI). Each stiffening and supporting structure (S) is embedded in the body (E) made of foam material so that said U-shaped bars (SI) have the lateral vertical portions (SI a) of the U shape substantially parallel and lateral to the walls of each seat (El) created inside said body (E), and so that said U- shaped bars (SI) have an intermediate portion (Sib) of the U shape substantially parallel to the lower surface (E3) of the body (E) made of foam material and substantially parallel to the lower surface or bottom (El a) of each seat (El) for the main floor reinforcement bars (F).

In particular, each U-shaped bar (SI) of the stiffening and supporting structure (S) has its lateral portions (SI a) positioned at a wider distance from one another than the width of each seat (El) in the body (E) so that they are substantially embedded in the foam material of the body (E). In addition, the intermediate portion (Sib) of each U-shaped bar (SI) lies parallel and proximal to the lower surface (E3) of the body (E) made of foam material.

The longitudinal round bars (S2) of the stiffening and supporting structure (S) connect all of said U-shaped bars (SI), keeping them in position.

Some of said U-shaped bars (S 1 ) have a part of their lateral portions (S 1 a) that is partially bent towards the midline, i.e. towards the other lateral portion (SI a), and thus forms a portion (Sic) generically parallel to the intermediate portion (Sib).

These bent portions (Si c) extend from the lateral walls (Elb) of the seats

(El) in the body (E), generically parallel to the bottom (El a) of the seats

(El) and spaced from said bottom (El a) of the seats (El).

Said bent portions (Sic) of the lateral portions (SI a) of said U-shaped bars

(S I) support the main floor reinforcement bars (F) at a distance from the lower surface or bottom (El a) of each seat (El) in the body (E) of the novel formwork. The various stiffening and supporting structures (S) in the body (E) are designed to be connected and joined together by additional longitudinal round bars (S3) orthogonal to and attached to the longitudinal round bars (S2) of the various formwork stiffening and supporting structures (S).

Moreover, said disposable formwork is designed to include at least two of said metal structures (S), wherein each of said U-shaped bars (SI) is coupled, by means of an intermediate portion (Sli), to a U-shaped bar of the other metal structure (S).

Said metal stiffening structures (S) are conveniently obtained from a single welded mesh (El), 111 with one or more bends to form a U shape, wherein said welded mesh (El) is placed at least partially on the lower part of the body (E) made of foam material, said welded mesh (El) having one or more bends to form a U shape and being positioned also underneath said seats (El) to serve as the ribbing for the floor.

The novel formwork can additionally comprise a further welded mesh (R) incorporated in the body (E) made of foam material and positioned underneath the U-shaped bars (S I) and the longitudinal round bars (S2), in the vicinity of the lower surface (E3) of said body (E) made of foam material (Figure 1). Said welded mesh (R) enables and facilitates the bonding of a coating of plaster to the underside of the novel formwork and to the floor.

The novel formwork can also be designed to include anchoring means (G, Gl) attached to said metal structure (S) so as to enable the attachment of the novel formwork to the underside and of coating elements, such as panels of plasterboard (Figure 7) to the floor.

The metal stiffening and supporting structure (S) of the novel formwork can also be designed to include and be joined, already during the manufacturing process, to the main floor beam reinforcement bars (S4) in accordance with the design calculations, as shown in Figure 4. The making of the floor thus only involves installing the novel formwork and casting the concrete.

The longitudinal round bars (S2) for connecting and joining said U-shaped bars (SI) can be designed so that they are all located inside said U-shaped bars (SI) (Figure 6), or all located outside said U-shaped bars (SI) (Figure

4), or so that some are located on the inside and others are located on the outside of said U-shaped bars (SI) (Figure 3).

The body (E) can be designed to include seats (El, E4) generically orthogonal to one another for containing the main reinforcement bars (F) for parallel floor beams, and also the main reinforcement bars (F') for additional floor crossbeams.

The body (E) of the novel formwork can also be designed so that it has projections (E5) on the upper surface suited to support the welded mesh (R2) for the slab of the finished floor, as shown in Figures 1 and 5.

The upper surface of the body (E) of the novel formwork may also be designed to include projections (E6) or other types of finish so as to enable workers to walk on said body (E) of the novel formwork without slipping. The novel disposable formwork for making floors offers considerable advantages.

The novel formwork requires fewer supporting structures during its installation and the casting of the concrete, because the weight of the reinforcement bars, the cast concrete and the workers making the ribbed floor is partially supported by the stiffening and supporting structure (S). The novel formwork does not demand the use of spacer elements for the installation of the main floor beam reinforcement bars (F).

The novel formwork enables the main floor beam reinforcement bars (F) to be kept at a distance from the lower surface or bottom (El a) of each seat (El) so that said main reinforcement bars (F) are substantially covered completely with the cast concrete.

The novel formwork can be quickly and easily manufactured using any of the known methods, e.g. the sintering and expansion of the foam material in a moulding chamber, in which the stiffening and supporting structures (S) have previously been inserted.

Therefore, with reference to the above description and to the attached drawings, the following claims are expressed.