WO2008028986A1 - Recoverable formwork device - Google Patents

Abstract

The invention relates to a recoverable formwork device which has been designed preferably for concrete slabs reinforced with prestressed beams in the form of a recoverable metal module made from a laminar material that has been stiffened by means of folding and bending, preferably metal plates. Typically the invention takes the form of an arch with a cavity between the beams beneath the compression layer, such as to form a ribbed-type slab. The inventive device includes: a slightly curved upper horizontal branch which is symmetrical in relation to the centre line thereof and which has an angle of descent from said centre line towards the ends thereof, and two vertical branches which form an acute angle with the ends of the horizontal branch. Said vertical branches provide support for the supporting means that rest on the beams.

Description

 STATE RECOVERY FORMWORK DEVICE OF THE ART OF THE INVENTION

Field of the Invention

The present invention relates to a novel recoverable formwork device preferably applied in the construction of reinforced concrete slabs with prestressed joists.

Description of the prior art

The formwork systems currently used in the works for the construction of slabs, use the method that is commonly called lost materials or simply, lost formwork.

In order to carry out this type of formwork, the joists are mounted on sturdy beams propped up with beams and formwork columns, among them the lost formwork material (ceramic bricks, compressed concrete blocks or expanded polystyrene blocks) is supported; on this set the armor is laid and finally the concrete is cast.

Also known by those skilled in the art are formwork systems recoverable by hoisting for the construction of vertical structures, such as walls, partitions and their equivalents; In general these types of formwork are formed by wooden structures or similar materials forming molds where the concrete is cast.

SUBSTITUTE SHEET (RULE 26) Returning to lost formwork, the materials normally used for this type of practice between prestressed joists are: hollow ceramic bricks, expanded polystyrene blocks or compressed concrete blocks.

In this type of lost formwork, either the one that uses ceramic bricks or the one that uses compressed concrete blocks, the lost formwork material placed between the prestressed joists is left in the place where it was arranged, and when casting the reinforced concrete, becomes part of the filling of the structure. Clearly this characteristic of lost formwork increases the weight of the structure to be built. According to those skilled in the art, this weight gain is a minimum of approximately 20%.

With respect to lost findings that use expanded polystyrene, which do not significantly increase the weight of the structure, they have the disadvantage of being highly flammable materials and also emit toxic fumes if they are reached by fire. Also expanded polystyrene is a high-cost material, and difficult to obtain in certain areas, due to shortages.

On the other hand, when the lost formwork systems mentioned above are used, areas of materials with very different mechanical properties are generated in the structure. For this reason, people who understand the subject will know that it is common to see catastrophic failures in bricks or concrete blocks that are part of the lost formwork of a

SUBSTITUTE SHEET (RULE 26) ceiling, due to, for example, thermal solicitations, structure settlements or earthquake solicitations.

These solicitations will generate displacements in the structure formed by the lost formwork material and the slab. These displacements may be accompanied by the slab (because it has a certain flexibility), but the bricks or ceramic blocks, firmly attached to the slab, will not have the flexibility to accompany the movement of the slab and will fail before such solicitation, taking place the explosion of the bricks or ceramic blocks generating situations of risk for the people.

Although these failures affect the formwork material (filling) and do not usually affect the strength of the structure, they are equally risky due to the shedding of materials caused.

Another common problem observed by those skilled in the art are the different lights to be saved by ceramic bricks or blocks of compressed concrete.

With the common methods of lost formwork, it is only possible to save measures of multiple lights of half a module of ceramic brick or block of compressed concrete, because these elements are sold only in whole and halves.

Another disadvantage observed in ceramic bricks, compressed concrete blocks or expanded polystyrene blocks used in the lost formwork described up to

SUBSTITUTE SHEET (RULE 26) Now, it is that they produce waste due to breakage and insecurity for operators and equipment due to danger when they are traveled once placed in their place.

Another of the disadvantages of ceramic bricks and blocks of compressed concrete is that they are hollow and when the reinforced concrete beams are filled, concrete also enters these gaps, which generates material loss and weight gain in the structure.

Due to the surface characteristics of the formwork materials used so far, when removing columns and formwork beams, the exposed surface is rough and has numerous imperfections. It is therefore commonly used in art for aesthetic reasons, to provide suspended or applied ceilings, producing an increase in weight, costs and work time.

Ceramic bricks and concrete blocks also generate losses of water from concrete kneading by absorption and by multiple joints, since their length is 25 cm, as this separates some joints from the others.

Another of the disadvantages of lost formwork is that in the sense of stop they are presented in only three standard measures.

BRIEF DESCRIPTION OF THE INVENTION

SUBSTITUTE SHEET (RULE 26) It is therefore an object of the present invention to provide a recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists, in the form of a domed module made of folded and curved sheet material, preferably metal sheets, as formwork material whose weight It will be much smaller than that of ceramic or compressed concrete blocks (4: 1 weight ratio). This feature of lower weight, introduces technical, economic and safety advantages in the work in which they are applied.

It is also the object of the present invention, to provide a recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists that allows, by the removal of bolts for market use, to remove said formwork material after the setting time.

In this way, the use of these devices allows not to leave lost formwork material as filler material in the structure, so that areas with mixed mechanical properties are not generated, generating a homogeneous structure.

It is also the object of the present invention to provide a recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists by means of which it is possible to cover any light between reinforced concrete beams by means of the use of recoverable formwork modules of different sizes and from

SUBSTITUTE SHEET (RULE 26) adjustment formwork modules that are overlapped, compared to common modules.

It is another object of the present invention to provide a recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists whose use does not generate waste or leftover formwork material.

It is still the object of the present invention to provide a recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists where the laminar surface of said formwork devices in contact with the concrete is smooth and polished and non-adherent, in order to that at the time of decoupling, the resulting concrete surface is of the type seen, with adequate surface termination; being able to obviate in this way the application of an additional ceiling.

It is still the object of the present invention to provide a recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists whose use allows height variation in the void left between joists according to the slab load conditions, as well as not generating absorption of kneading water, reducing open joints, facilitating the vibrating of concrete.

BRIEF DESCRIPTION OF THE DRAWINGS

SUBSTITUTE SHEET (RULE 26) For clarity and understanding of the object of the present invention, it has been illustrated in several figures, in which the invention has been represented in one of the preferred embodiments, all by way of example, where:

Figure 1 is the cross-section of the recoverable formwork device of folded and curved stiffened sheet material, preferably metal sheets, in one of its preferred embodiments. The surface that is in contact with the concrete is curved or at an appropriate angle to facilitate the release.

Figure 2 shows a perspective view of the recoverable formwork device of Figure 1.

Figure 3 shows the arrangement of the formwork devices between prestressed joists, simply supported by the latter by means of support elements (1) at a predetermined height. In this figure you can see the final folding of stiffening in the lower part of the vertical branch

Figure 4 shows a perspective view of a typical arrangement of a tandem or arrangement of folded sheet formwork devices arranged between prestressed joists with the inclusion of an adjustment module.

Figure 5 shows a first variant of the cross-sectional profile of the formwork device that is applied with the same principle according to the aesthetic termination that is intended to be achieved.

Figure 6 shows a second variant of the cross-sectional profile of the formwork device that is applied with

SUBSTITUTE SHEET (RULE 26) identical principle according to the aesthetic termination that is intended to be achieved.

Figure 7 shows a detail of the support element of the lost type of straight rectangular prismatic form together with the screw, of market use, that supports it.

Figure 8 shows a detail of the support element of the lost type, of a square-shaped pyramidal trunk together with the screw, for market use, that supports it. The hole left by the support when it is removed is filled with fine, hardened concrete or other material compatible with the slab concrete. The angle of the wedge of the support allows its removal.

Figure 9 shows the recoverable formwork device when used without the support brackets on the vertical branches. It is clearly observed that in this case, the formwork device is simply supported on the formwork beam, which is drawn with dashed lines.

Figure 10 shows the recoverable formwork device mounted on prestressed joists using the support means. Said support means located in the middle part of the vertical branch of the formwork device to achieve a different measurement of vacuum according to the demand of the calculation of the slab due to its loading state.

Figure 11 shows the recoverable formwork device mounted on prestressed joists using the support means. Said support means located in the lower part of the vertical branch of the formwork device to achieve another measurement other than vacuum according to the demand of the calculation of the slab due to its load state.

SUBSTITUTE SHEET (RULE 26) DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures, we see that the invention consists of a recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists in the form of a ^' recoverable module, made of a folded and curved stiffened sheet material, preferably metal sheets, as depicted in fig. 1. Its typical shape is like a vault and leaves a gap between joists below the compression layer, resulting in a ribbed slab type.

The device of folded sheet in vaulted form, has a horizontal upper branch (6) slightly curved, symmetrical with respect to its midline nn and with a drop angle (β) from it towards its ends (7) and (8), and two vertical branches (9) and

(10) forming an acute angle (δ) with the ends (7) and (8) of said horizontal branch of the device. These vertical branches

(9) and (10) will provide the support for the support means (1) that will rest on the joists (2) and in their lower part they have a final folding of stiffening that, in addition to mechanical rigidity, gives it greater resistance in the I handle

The support elements may be located in different positions along the vertical branches of the formwork device, as shown in Figures 10 and 11, to achieve a different measurement of vacuum according to the demand for the calculation of the slab due to its state of charge

SUBSTITUTE SHEET (RULE 26) As shown in Figure 3, the recoverable formwork modules step through the supports (1) on the joists

(2); these are supported on formwork beams placed perpendicular to the joists (2), supported in turn by formwork columns that transmit the loads to the floor.

At this point it should be noted that it is also possible to mount the recoverable formwork modules, without the use of the mentioned support means (1). In this way the formwork devices will simply rest on the formwork beams, as shown in Figure 9, secured only by their own weight.

As already mentioned, the location of the supports (1) can be varied in height, along the vertical branches (9) and (10), so that the supports can be supported at different heights to achieve different vacuum measurements according to the demand of the calculation of the slab due to its state of load.

To use the recoverable formwork device, several of said devices are mounted in tandem, or forming an arrangement, as seen in fig. 4; Type modules are placed, ie modules of standardized lengths

(4), and adjust the length of the tandem or arrangement to the light to be covered by using the adjustment modules

(3) . These adjustment modules are of similar characteristics as the type devices, and are used when it is necessary to save lights that are not covered exactly with the use of common formwork modules (whole, medium, quarter, three quarters or eighth).

SUBSTITUTE SHEET (RULE 26) The way to mount the adjustment modules is, overlapping the ends of said adjustment modules, with the ends of said type modules, in order to cover exactly the desired light. Finally, at the ends of the tandem or arrangement, covers (5) are placed to avoid concrete spills. Likewise, the joints between modules are made butt, in the case of union of type modules, or in an overlapping way if it is the union with adjustment modules. All these joints, butt or overlapping, must be sealed and conveniently fixed, to avoid relative movements between them, which would produce concrete leaks.

The formwork is carried out by removing the screws that fix the formwork to the supports (1), the latter can be lost in the reinforced concrete, or they can be removed according to the support model used. A detail of the supports of the lost and removable type respectively is shown in Figures 7 and 8.

The lost support of fig 7 is a straight rectangular prismatic volume of resistant material of approximately 7 cm3 in volume, with a metal thread insert waiting for the screw for market use. The recoverable formwork system that uses this type of supports allows them to hang ceilings, pipes, artifacts, etc. structures.

On the other hand, figure 8 shows the removable type supports. These are square-shaped pyramidal trunk, whose approximate volume is 7cm3. They also have a

SUBSTITUTE SHEET (RULE 26) Metal thread insert waiting for the market use screw.

In both cases, lost media (fig. 7) or removable

(fig. 8), the angle (α) with which the support rests on the joist is the same, this angle (α) has the function of retaining the formwork module in place, avoiding relative movement with respect to The joists.

The laminar surface of the formwork modules in contact with the concrete is smooth, polished and lacks adhesion, whereby at the time of release the resulting concrete surface is of the type seen; being able to obviate the application of additional ceiling. In addition to being reusable modules, it is a more cost effective method than the previous ones.

SUBSTITUTE SHEET (RULE 26)

Claims

CLAIMS Having thus described and determined the nature of the present invention and the manner in which it is to be carried out, it is claimed to claim as property and exclusive right: 1. A recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists characterized in that it comprises: A module of laminar material material stiffened by folding and curved in a domed shape, which has a slightly curved upper horizontal branch, and two vertical branches that support the support means that will rest on the joists; 2. The recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists of claim 1 characterized in that: said horizontal branch of said single module of domed material is slightly curved, symmetrical with respect to its midline and with a angle of broth from it to its ends; and because said two vertical branches that form an acute angle with the ends of said horizontal branch of the module. Said vertical branches will support the support means that will support the joists; SUBSTITUTE SHEET (RULE 26) 3. The recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists of claim 1 characterized in that: in said two horizontal branches of said formwork module holes are made to fix the support means that support the element on the joists , at a certain distance from its lower ends, according to the thickness of the slab that is desired to be obtained according to the state of loading of the slab. 4. The recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists of claim 1 characterized in that: the supports used are of the straight prismatic type of rigid material and suitable for receiving a screw for market use in order of holding said module in position during the concrete casting task, and which are left in place once the formwork has been performed. 5. The recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists of claim 1 characterized in that: the supports used are of the removable type of square-shaped pyramidal trunk also suitable for receiving a screw for market use in order of holding said module in position during the concrete casting task, and removed from its place while the formwork is taking place. 6. The recoverable formwork device preferably developed for reinforced concrete slabs with prestressed joists of claim 1 characterized in that: it has different lengths in order to constitute standard modules for saving standardized lights between joists or has SUBSTITUTE SHEET (RULE 26) shorter lengths to constitute adjustment modules, to save lights other than normalized ones. 7. A method for using the recoverable formwork device of claim 1 characterized in that: - For the use of said devices in a slab formwork task, a plurality of devices are mounted in tandem or arrangement; - Said tandem or arrangement is constituted by: a) Type modules, that is to say modules of standardized lengths, b) Adjustment modules that are used to adjust the length of said tandem or arrangement to that of the light to be covered by. - The joints between modules are made butt, in the case of union of type modules, or in an overlapping way if it is the union with adjustment modules. - All these joints, butt or overlapping, must be sealed and fixed, by some convenient method, to avoid relative movements between modules and material leaks. - All this set is mounted on the joists that in turn support on sturdy beams propped up with beams and formwork columns. SUBSTITUTE SHEET (RULE 26)