UNIT FOR THE CONSTRUCTION OF SIAB FOUNDATIONS

DESCRIPTION

The present invention refers to a unit for the construction of slab foundations. In the construction field, slab foundations are used on so-called "expansive" ground, or rather on ground which is subject to variations in volume following wet and dry cycles, and comprising a grid of bearing beams which lean directly onto the ground and a composite completion slab, which is produced on the bearing beams in such a way as to form with the latter a number of cavities which are uniformally distributed on the ground inside of which the ground itself can discharge during its own expansion. The sizing of the beams must be able to endow rigidity to the entire slab foundation, and must be able to define a supporting surface on the ground for each beam in such a way that the weight of the slab foundation divided by the support surface results in a permissible stress which is always greater than the stress of the ground in expansion thus containing the movements of the foundation.

Technical literature in the construction field makes known units for the construction of slab foundations comprising a number of domes made of

cardboard, or in some cases, of polystyrene, which are laid side by side at a determined distance from each other in order to form a gridwork of channels, inside which reinforcing bars are subsequently positioned before the whole unit is covered with concrete. These units with cardboard domes present some disadvantages which are described and dealt with in the American patent No. US 5,540,524, in which is made known, instead, a unit for the construction of slab foundations provided with a number of domes made of plastic material, which present four slightly inclined lateral walls and an upper horizontal wall, and which are suitable for being distributed on the ground in such a way as to form the above-mentioned gridwork of channels which may be filled with concrete .

The American patent US 5,540,524 also describes that the unit comprises a number of tension tie-rods, which are suitable for pre-tensioning the concrete inside the channels, and which extend inside sheaths which are in turn arranged along the channels before the concrete is cast.

The unit for the construction of slab foundations which is described in the above-mentioned American patent, while resolving the technical

problems which are due to the use of cardboard domes, presents some disadvantages which limit the speed at which the foundation may be laid, a task which is essentially left to the fixers and any eventual reference systems that they might use, such as, for example, the production of a grid of tightened cables above the ground in order to delimit the single area where each dome is to be laid. Furthermore, even the laying of the tension tie-rods is not guided inside the channels in any way whatsoever, to the detriment of the speed of the laying operation, once again, as well as to the precision of the production of the relative slab foundation.

The American patent No. US 6,550,207 describes a unit for the construction of aerated slabs which comprise a number of modules of domes made of plastic material, and a number of auxiliary connecting elements, which are shaped, substantially like arches or cradles, and which are arranged in an intermediate position between two adjacent modules of domes in order to connect the adjacent modules of domes themselves to each other in univocal fashion at a reciprocal positioning distance.

The American patent No. US 6,550,207 describes modules of domes made of groupings formed of one, two

or four domes, and in which the domes of each module are coupled one to the other and are coupled to the domes of the other modules by means of the above- mentioned auxiliary connecting elements, the presence of which, while resolving on the one hand the problem of defining the reciprocal positioning distance between the various domes, or rather the various modules of domes, during the laying process, does not, on the other hand, permit the production of a slab foundation due to the fact that the said auxiliary elements form respective compartments on the ground once the concrete has been cast, thus impeding the production of the above-mentioned gridwork of bearing beams directly on the ground with specific and well-defined supporting surfaces.

The aim of the present invention is to produce a unit for the construction of slab foundations which will be quick and easy to lay into position.

According to the present invention, a unit for the construction of slab foundations will be produced, comprising:

- a number of modules of domed bodies which are made of plastic material and which are suitable for being placed in position in a construction site with an own concavity turned towards the construction site

itself and in conformity with modules of at least one domed body arranged laterally in relation to each other;

- a number of channels which are formed by the modules of the adjacent domed bodies and which are suitable for being filled with aggregating material in order to form bearing beams; and a number of interconnecting elements which are arranged in an intermediate position between at least two adjacent Modules of domed bodies in order to connect to each other the adjacent modules of domed bodies themselves defining in univocal fashion a reciprocal positioning distance; the unit being characterised by the fact that the said interconnecting elements comprise two firewalls which are connected to respective domed bodies facing each other along a said channel and distancing means which are interposed between the two firewalls in such a way as to transmit the static load of the bearing beams directly onto the site where they are to be laid and in order to determine the said reciprocal positioning distance.

The present invention will now be described with reference to the attached drawings, which illustrate a non-limiting form of embodiment of the

present invention, and in which:

- FIGURE 1 is a plan view of a first preferred form of embodiment of a unit for the construction of slab foundations according to the present invention; - FIGURE 2 is a perspective view on a reduced scale of the unit which is shown in FIGURE 1;

- FIGURE 3 illustrates, on an enlarged scale and in lateral elevation, a detail of the unit which is shown in FIGURE 1; - FIGURES 4 and 5 illustrate respective details of the unit which is shown in FIGURE 1 ;

- FIGURE 6 is a plan view of a second preferred form of embodiment of a unit for the construction of slab foundations according to the present invention; and

- Figure 7 is a side view of the unit of Figure 6.

With reference to FIGURES 1 and 2, the number 1 indicates a unit for the construction of slab foundations in its entirety, in which a number of beams made of reinforced concrete form a gridwork of beams which lean directly on, or rather are in contact with, the ground where they are laid, and are also connected to each other by a composite completion slab above the beams themselves.

The beams, as well as the composite slab, are produced by filling the site where they are laid by means of casting concrete over the unit 1, which comprises a number of modules M arranged on the ground in such a way as to define both an upper reference surface S for the composite slab and a gridwork of channels 2 which are suitable for being flooded with concrete for the formation of the above- mentioned gridwork of beams. Each module M comprises, in its turn, a determined number of domed bodies C, which are made of plastic material in such a way as to remain internally hollow in order to give blowholes for the expansion of the ground, and which may be defined, as is illustrated in FIGURES 1 and 2, by domes, to which the description which follows will make explicit reference without in any way losing its general nature .

Each dome C comprises an upper plane Cl defining with the planes Cl of the other domes C the surface S, and four lateral windows C2 , each of which starts directly from the ground and is encircled by a shaped border C3 for the substantially sealed connection of one dome C with the other domes C of the same module M, in the case in which the latter

presents more than one dome C as is in fact so in the case which is being described where each module M comprises four domes C which are connected to each other in order to form a square. In addition, the upper plane Cl of each dome C may be flat as illustrated in the previously cited American patent No. US 5,540,524, or may be arched as illustrated in the previously cited American patent No. US 6,550,207: in any case, the import of the present invention is not limited by the specific shape of the domes C, which may be selected according to the specific production demands of the unit 1.

As is also illustrated in FIGURE 3, the unit 1 also comprises a number of interconnecting elements 10, which are arranged in an intermediate position between at least two adjacent modules M in order to connect the adjacent modules M to each other defining in univocal fashion a reciprocal positioning distance, and comprising a firewall 20 which may be coupled to each dome C facing along a channel 2 and at least two spacers 30 with a space between them if order to leave the ground free along the channels 2 themselves .

Each firewall 20 comprises a wall 21 for laterally closing a window C2 of the relative dome C,

a shaped connecting border 22 which is integral with the wall 21 and presenting a shape which is complementary to that of the relative border C3 in order to be engaged in the border C3 itself, and two engaging housings 23, which are arranged at the opposite lower ends of the wall 121, and are defined by respective hollow cylindrical bodies which are integral with the wall 21 itself.

The wall 21 of each firewall 20 is inclined towards the relative window C2 and defines with the wall 21 of the firewall 20 which is arranged in front a portion of the channel 2 which, thus, presents a substantially trapezoid section which tapers towards the ground where the foundation is to be laid. Still in accordance with the illustration which is shown in FIGURE 3, the firewalls 20 may also be of two kinds: a firewall 20', in which the shaped border 22 is arranged in contact with the relative border C3 of which it traces the shape, and a firewall 20' , in which the shaped border 22 presents a slit in the shape of a half-moon inside which is positioned a lip C6 of the border C3.

In addition, according to a second form of embodiment which is not illustrated, but which may be easily understood from the above description, the

firewalls 20 may also be obtained directly in a single piece with the domes C with the further advantage of a reduction in the assembly time of the unit 1. According to what is better illustrated in FIGURE 4, each spacer 30 comprises a shaped base plate 31, two collapsible pins 32 which are arranged at opposite ends of the base plate 31 and which may be snap-engaged inside a relative housing 23, and an upper rib 33, which is integral with the base plate 31 and which presents three saddles 34 which are at an equal distance from each other for housing respective reinforcing elements F, such as bars or sheaths . The base plate 31 is shaped in correspondence with the pins 32 in such a way as to leave a gap between it and the ground where the foundation is to be laid once the pins 32 have been inserted into the housings 23 of two different firewalls 20, and in particular, presents a double fold 35 in the shape of an L in such a way as to be substantially aligned with the upper border of the rib 33. Each pin 32, instead, is defined by two semi -cylindrical shells which are engaged in the plate 31 and are distanced from each other by a split, 37, and presents a

security turn-up which is arranged along he free end of each shell 36 in order to prevent the accidental exit of the pin 32 itself from the relative housing 23. According to what is illustrated in FIGURE 5, and with reference to FIGURE 1, when the housing 23 of four firewalls 20 are arranged in a rectangle inside the channel 2, with the aim of achieving greater stability and also speed of the connection, each spacer 30 comprises two further base plates 31' which are arranged transverse to the base plate 31 in order to define a rigid connection between two spacers 30.

Referring to a module M formed by four domes C like that which is illustrated in FIGURES 1 and 2, laying a unit 1 occurs by assembling each module M on the ground where it is to be laid and subsequently closing eight windows C2 with the same number of firewalls 20. Gradually, as each module M is laid in place, the one which is subsequently laid in place is connected to the one which was laid before by means of the spacer 30, in the form with two plates 31 as well as in the form with four plates 31' . In the latter form the spacers 30 mean that the laying in place is rendered even more uniform and the distance

between the two adjacent modules M permits it to be carried out at high speed, with the additional certainty of producing channels 2 which are also of uniform size. When the unit 1 is produced with more than one module M which, it should be remembered, may also be formed by a single dome C, or by two or four domes C according to different cases, the reinforcing bars or sheaths F are positioned along the channels 2 thus formed and become part of the unit 1 and are supported inside the saddles 34 which maintain them at an equal distance from each other and parallel to each other.

At this point, in order to obtain a slab foundation, it is sufficient to cover the unit 1 itself with concrete, flooding the channels 2 and covering the whole of the surface S.

According to what is illustrated in FIGURES 1 and 2, the domes C of each module M also present grooves C7 which are obtained along the respective plane Cl in order to house additional reinforcing bars or sheaths F, which will become part of the composite slab.

Taking into account the high level of freedom of assembly of the unit 1 which has been described

above it is also possible to produce a slab foundation with beams in a single direction as well as with a gridwork of beams in that it is sufficient to connect several modules M directly to one another in order to form a series of modules M and connect each series of modules M by means of the elements 10 which have been described above.

In addition, with the aim of further isolating the bearing beams from the ground where the foundation is to be laid when the latter might be, for example, particularly damp, the two spacers 30 may be connected to each other by means of a plastic membrane covering the ground where the foundation is to be laid along the channel 2 and via which would be discharged the static load of the relative bearing beam on the ground where the foundation is to be laid as such a plastic membrane would not be capable of exerting any resistance whatsoever.

Finally, as has been discussed above concerning the possibility of producing the firewalls 20 and the domes C in a single piece, it would also be possible to produce in a single piece the two firewalls 20 which face each other on the channel 2 by replacing the connecting elements 30 as described above directly with a connecting bridge produced,

preferably but not necessarily, of plastic material, the rigidity of which would be such as to guarantee the reciprocal positioning distance between the two modules M. The cited connecting bridge could be of any shape as long as it were suitable for discharging onto the ground the static load of the beam above it, or rather suitable for adhering to the ground where the foundation is to be laid itself once the casting of the concrete has been carried out. By way of an example, which, however, is non-limiting, the connecting bridge could have the form of a semi -tube along the opposite free sides of which the walls 21 of the two firewalls 20 were produced in a single piece.

In addition, the cited semi-tube could present its own concavity either turned towards the two firewalls 20, or turned opposite the two firewalls 20, and in the second case it should have a rigidity such as to ensure the correct reciprocal positioning distance between the two firewalls 20 themselves and also such as to be able to collapse at the opportune moment under the weight of the concrete casting in order to permit, as has been stated several times, the transmission of the static load of the relative

beam onto the ground where the foundation is to be laid.

It is evident from the above description that the spacing elements 30 can connect two firewalls 20 which face each other either in discontinuous fashion leaving the ground on which the foundation is to be laid in direct contact with the above-mentioned bearing beams, or in continuous fashion thereby completely isolating the bearing beams from the ground but, in both cases, still determining the reciprocal positioning distance between the firewalls 20 or rather between the modules M facing onto the same channel 2.

Figures 6 and 7 illustrate a unit 1' for the construction of slab foundations which is substantially similar to the unit 1 from which unit 1' differs as the spacers 30 are defined by a U-shape bar whose opposite extremities 32' are engaged inside a relative housing 23. The U-shaped bar 30 further comprises an intermediate portion 31' which links together the two opposite extremities 32' and which could also presents some saddles (not illustrated) which are able to house respective reinforcing elements F, such as bars or sheaths.

Furthermore, in the unit 1', the interconnecting elements 10 further comprises another U-shaped spacer 30' , whose opposite extremities 32" are engaged inside a respective housing 23' which are arranged at the top of each firewall 20. Also the U- shaped spacer 30' comprises an intermediate portion 31" which links together the two opposite extremities 32" and which could also presents some saddles (not illustrated) which are able to house respective reinforcing elements F, such as bars or sheaths.

It is intended that the present invention should not be limited to the form of embodiments which are herein described and illustrated, which are to be considered as examples of a form of embodiment of the unit for the construction of slab foundations, and which may instead be subject to further modifications relating to the shape and disposition of the parts, as well as to details pertaining to construction and assembly.