EP0617180A2

EP0617180A2 - Products for the fabrication of floors with lightening box elements and floors made with these products

Info

Publication number: EP0617180A2
Application number: EP94104407A
Authority: EP
Inventors: Delmo Maffezzoni; Filiberto Muccioli
Original assignee: ONDAPLAST SpA
Current assignee: ONDAPLAST SpA
Priority date: 1993-03-26
Filing date: 1994-03-21
Publication date: 1994-09-28
Also published as: IT1264099B1; ITBO930122A1; EP0617180A3; ITBO930122A0

Abstract

Box elements (4-104-204) made from extruded cellular sheets of polypropylene and/or other suitable waterproof plastic materials, filled if necessary, are disposed in the space between the metal lattices (3) projecting from the reinforced concrete slab (1-2) of a floor, and are fixed over the whole length of this space, with or without interruptions, and act as lightening elements. The box elements are downwardly open, are provided with transverse closing and stiffening walls (8) fixed by mortising and/or other suitable means and suitably distributed over the whole length of the said elements, which are preferably also provided with small lateral openings (7-10) which prevent the entry of the floor finishing casting but which allow the water to flow freely, so that after the setting of the said casting the floor no longer releases liquid components.

Description

The invention relates to prefabricated floors, known as lattice slab floors. These products consist of a thin reinforced concrete slab in which are embedded the lower structures of the metal lattices, parallel to and equidistant from each other, in numbers variable according to the dimensions of the slab. There is a known method of disposing on the slab, in the space between the lattices, polystyrene blocks which, when the floor is in use, have a lightening function, replacing the concrete where this is not required to perform important static functions. However, the use of polystyrene has many disadvantages which may be summarized as follows. When used at high density, polystyrene is unacceptably expensive, and is undesirable because of the effects on fire safety owing to the considerable mass exposed to combustion. When used at low density, as is normally the case, it absorbs water which it then releases over an indefinite period, with serious damage to the plaster and any other elements associated with the floor. The polystyrene inserts have low mechanical strength, and may therefore fracture, thus changing the designed floor dimensions, while parts of these inserts may fall between the lattices and compromise the quality of the casting ribs. Owing to the considerable volume of the polystyrene blocks, these are expensive to transport to the site of use and present storage problems. Over a period, polystyrene waste causes considerable problems of a functional, aesthetic and ecological nature, especially since it is difficult to dispose of or reclaim. Other forms of lightening proposed up the present as alternatives to polystyrene, such as perforated brick blocks, lightweight concrete blocks, elements made of mineralized wood fibre mixed with concrete, and solid aerated concrete elements, are all of limited usefulness owing to the major operational restrictions which, for various reasons, each of them has.
The invention is intended to overcome these restrictions and disadvantages of the prior art with the following idea for a solution. The lightening elements disposed on the floors consist of box elements made from cellular sheets of polypropylene and/or other suitable plastic materials, filled if necessary, which have considerable mechanical strength, which do not absorb water, and which in case of fire have a limited mass exposed to the flame and do not evolve toxic gases. The sheets of this material are prepared by the manufacturer with suitable shapes and dimensions, with ribs and with cut-outs or punchings such that they can be transported flat to the site of use in and stacked on normal pallets, with consequent low costs in both the transport and the storage stage. On the sites, the punched and ribbed sheets are used to form box elements, open below, and with suitable longitudinal and transverse stiffenings, and these box elements are partially embedded in the concrete slab, in place of the former polystyrene blocks, being also provided laterally with suitable openings to permit the total discharge of water in the stages of prefabrication and storage, and in the subsequent stage of installation and completion of the floor casting.
Further characteristics of the invention and the advantages derived therefrom will be clearly understood from the following description of some embodiments of the invention, illustrated purely by way of example in the figures on the attached sheets of drawings, in which:

Figures 1 and 2 are plan views from above of two prefabricated floors according to the invention;
Figure 3 is a perspective view of the floor in Figure 1;
Figures 4 and 5 show two details drawn along the section lines IV-IV and V-V respectively in Figures 1 and 2;
Figure 6 is a perspective view of a different lightening element with a fretted profile;
Figures 7 and 8 show part of a floor using the lightening element in Figure 6, in transverse section at one end and in an intermediate part respectively;
Figure 9 is a schematic perspective view of a simplified embodiment of the floor;
Figures 10 and 11 show in section and in perspective view another embodiment of the invention;
Figure 12 shows in perspective view still another embodiment of the invention.

In Figures 1-3-4, the reference 1 indicates the casting of the prefabricated concrete slab, which is reinforced by the internal metal frame 2 and which has embedded in it the lower structure of the metal lattices 3 which are equidistant from each other and in any suitable number. On completion of the casting 1, while the concrete is still wet, there are disposed in the space of the slab between the lattices 3 box elements 4, preferably open below, made from extruded cellular sheets of polypropylene and/or other suitable plastic materials, composite and filled if necessary, of suitable thickness, suitably punched and jointed, in order to permit the formation of structures 5 with an inverted "U" section, formed by folding the sheet about the longitudinal joint lines 6 and having lateral vertical or inclined slits 7, open downwardly, into which are inserted trnasverse walls 8 with vertical or inclined disposition, provided with upwardly open slits 9, which engage with the portions of the lateral wall of the said structures 5 above the said slits 7. The transverse walls 8, also formed from cellular sheets of polypropylene or other material, secure the structure 5 in its channelled and downwardly open form and close it off at the ends to impart the necessary externally closed box shape, and simultaneously improve its mechanical strength since they are distributed uniformly over the whole extension of this structure and since they thus form supports and props for bracing. The tubular cavities of the cellular sheets from which the said parts 5 and 8 are made are orientated in a direction such that they impart the greatest strength to the whole lightening box structure. In their lower parts, the transverse walls 8 have additional lits 10 which partly emerge from the slab casting 1 and which have the important function of permitting the outflow of the water from the lightening structure, even in the final stage of use of the prefabricated floor.
If the box structure 4 has a considerable width, it may be formed from a number of structures 5 of lesser width, adjacent to each other, provided with corresponding transverse walls 8 or preferably joined by the said transverse walls 8, as in Figures 3, 4 and 10, 11 for example. In the embodiment according to Figures 3 and 4 the walls of the structures 5 which are in mutual contact and which are inside the box element 4 are shorter than the outer lateral walls and are joined to the transverse walls by means of mortise slits 7-9, similar to those of the outer walls. In the embodiment according to Figures 10 and 11 the walls of the structures 5 which are in mutual contact and are inside the box element 4 are of the same length as the outer lateral walls. In a variant embodiment which is not illustrated, the two inner lateral walls, in mutual contact, of the adjacent structures 5, as shown in Figures 1-3-4 and 10, 11 may be joined together by a folding line so that the two structures 5 may be formed by folding from a single cellular sheet of polypropylene. It is evident that the walls in mutual contact of the two adjacent structures 5 contribute to the imparting of a considerable mechanical strength to the lightening box element 4. It is to be understood that a box element 4 may be formed from more than two adjacent structures 5.
If the lightening box elements are to be of limited width or are to be tapered at the ends, as in Figure 2 for example, the end part 104 of each box element is made with a single inverted "U" structure 5 and with suitable transverse walls 8, as shown by way of example in the detail in Figure 5. This figure also shows the possible situation in which the transverse walls 8 may be connected more effectively to the portal structure 5-105 or 205 (see below) by means of one or more upper projections 11 of any shape such that they can be fixed by pressure into corresponding slots 12 of the upper part of the said portal structure. According to another variant which is not illustrated, the transverse walls 8 which close the ends of the box element may be connected by a joint line 6 to the ends of one of the walls of the portal structure 5-105-205 and may be connected to the other walls of the said structure by means of projections 11 and slots 12 of the type mentioned previously.
The ability of making box elements of any shape from the cellular sheet of plastic material makes it possible to meet the various requirements arising from the use of prefabricated floors. For example, if a floor with specific self-supporting characteristics is required, the lightening box element 204 may be made, as in the example illustrated in Figures 6-7-8, with a structure 205 with a fretted profile, formed by folding from a single cellular sheet provided with longitudinal joint lines 6 which, after folding, provides two downwardly open outer channels 13-113 and an upwardly open intermediate channel 14. On the lateral walls and on the intermediate base of the structure 105 there are provided slits 7 disposed in imaginary vertical or inclined planes spaced apart by a suitable amount, into which are inserted the transverse walls 8 provided with corresponding mortise slits 9 and lower drainage slits 10. At the ends of the structure 105 there are disposed transverse walls 8, as shown in Figure 7, which close all the channels 13-113-14, while the transverse walls mounted in the intermediate slits are of the type illustrated in Figure 8, being provided with a median slit or slot 15 which provides continuity of the channel 14 so that a concrete or reinforced concrete beam 16 can be formed in it, to improve the mechanical characteristics of the prefabricated floor. The beam 16 is connected to the slab 1 through apertures 17 made in the base of the channel 14 (Figure 6).
It should be understood that the ratio between the height of the stiffening box elements and the outer lattices 3, as shown in the drawings, is purely an example, and may be modified up to the point where the ratio is equal to one (as illustrated for example by the broken line in Figure 4) or may be a fraction, so that, when a number of prefabricated floors of the type in question are stacked on each other, their waight is transferred principally to the lattices and not to the lightening box elements, which are thus protected from bending and fracture. It should also be understood that the description refers only to certain possible, embodiments of the invention, to which numerous variations and modifications may be made, particularly in respect of construction, for example in relation to the shape and composition of lightening box elements.
Moreover, it is possible for the lightening box elements to be completed on site, with the rapid fixing of cellular sheet parts to other ordinary or auxiliary parts previously fixed to the slab 1 and possibly collapsible, to contain the overall dimensions of the prefabricated pieces during storage and transport. For example, Figure 9 shows a variant of this sort in which continuous strips 18 of cellular polypropylene or other sheet are embedded longitudinally in the slab 1 with symmetrical disposition, disposed alongside and parallel to the lattices 3 and provided with upwardly open slits 19. When such a floor is installed, the lightening box elements are completed by mounting the transverse walls 8 on the strips 18 and then mounting on these walls the longitudinal modules 4 or 104 or other suitable modules which in this case will be designed to be suitably fixed (by any suitable fastening means) to the slab or to the lattices to prevent the entry into these walls of the floor finishing casting, the whole in a way understandable and easily executed by those skilled in the art.
According to the embodiment shown in Figure 12, continuous stips 20 are embedded in the slab 1 with symmetrical disposition, disposed alongside and parallel to the lattices (not shown). The said continuous strips 20 are provided with suitable anchoring means such as holes 21. When such a floor is installed, the lightening box elements are completed by mounting the longitudinal modules 304, to which there have been already fixed the transverse walls 308 by means of appendices or projections 311 which fit into corresponding slots 312 provided in the walls 305 of the longitudinal modules. The said longitudinal modules 304, completed with the trnasverse walls 308 are secured in place onto the continuous strips 20 by means of bolts 23 (or any other suitable anchoring means) which pass through corresponding holes 22 provided in the side walls of the structure 305 and pass also through the anchoring holes 21 provided in the strips 20. For the same purpose, it is possible for the lightening box elements to be wholly made on site and temporarily fixed in the extrados of the slab, for example with metal wire ties or other means, fixed to the lattices 3 and/or to the reinforcement 2 in the case of a floor made completely on site.

Claims

Products for the fabrication of floors consisting of a reinforced concrete base (1-2) in which are fixed the lower structures of steel lattices (3) which form the reinforcement for the finishing casting of the said floor, characterized in that they comprise, as lightening elements for the finishing casting, disposed on the said base, in the spaces between the lattices, over all or part of the length of these spaces, box elements (4-104-204) made with sheets of any material having sufficiently low weight and high mechanical strength and preferably not absorbing water, these box elements being suitably closed in the visible parts and being downwardly open or provided with suitable lower openings and being fixed with any suitable means to the base and/or to the lattices, in such a way that the floor finishing casting cannot enter them and that the water can be completely discharged through their lower open portion and/or lower openings, so that after the setting of the casting the floor does not release any further liquid components.
Products according to Claim 1, in which the lightening box elements (4-104-204-304) are provided laterally with suitable drainage openings (7-10), appropriately distributed and such that the floor finishing casting cannot pass through them.
Products according to Claim 1, in which the lightening box elements (4-104-204-304) are provided with transverse walls (8-308) for structural stiffening, appropriately distributed over all or part of the length of these elements.
Products according to Claim 1, in which the lightening box elements (4-104-204-304) are made from extruded cellular sheets of polypropylene and/or other suitable plastic materials, filled if necessary with other suitable materials, and of suitable thickness.
Products according to Claim 4, in which the cellular sheets of polypropylene or other suitable material, used for the formation of the lightening box elements (4-104-204), are provided with suitable joint lines (6) along which they can be folded to form at least one structure (5-105-205) with an inverted "U" profile, and are provided by punching with suitable slots or slits (7), which are located at least in the lateral walls of the said structure, and in which may be inserted and fixed corresponding portions of transverse walls (8) also formed from cellular sheets of the said material and provided by punching with slots or slits (9) which can be engaged by parts of the said structure, the whole in such a way as to produce, a downwardly open box element, closed at the ends, and provided with a plurality of transverse walls which are vertical and/or inclined and are suitably distributed over the whole length, to improve the mechanical strength of the whole box element.
Products according to Claim 5, in which the transverse walls of the lightening box elements (4-104-204) are provided in their lower with slits (10) which emerge from the prefabricated slab casting (1-2) to permit the complete outflow from the lightening box element of water from the floor finishing casting or from other sources.
Products according to Claim 5, in which the inverted "U" structure (5-105-205) of the lightening box elements is provided on the lateral walls with downwardly open slits (7) into which are inserted the transverse walls (8) which in turn are provided in the portion inserted in the said slits with corresponding upwardly open slits (9) which are inserted into corresponding portions of the vertical walls of the said structure.
Products according to Claim 7, in which the transverse walls (8) of the lightening box element (4-104-204) are provided at their perimeters and in one piece with one or more projections (11) of round, elliptical, diamond or other shape, capable of being inserted by pressure and fixed in corresponding slots (12) provided in the walls of the inverted "U" structure (5-105-205), or of being fixed in other ways to this structure, with stitches or other means, to form a secure and distributed connection which avoids any deformation of the said walls under the force of the floor finishing casting.
Products according to the preceding claims, in which the transverse end walls (8) of the lightening box elements (4-104-204) may be integral with and joined to the ends of one of the walls of the portal structure (5-105-205) which forms the said box elements and may be installed with projections (11) and slots (12) or other suitable means.
Products according to the preceding claims, characterized in that when the lightening box element (4) is of considerable width it is made with two or more elements of lesser width, adjacent, and more able to withstand the stresses of the floor finishing casting.
Products according to Claim 10, in which the adjacent lightening box elements (4), of limited width, used to form a single box element of considerable width more able to withstand mechanical stresses, are interconnected by the transverse walls (8) which are common to these elements.
Products according to Claim 11, in which the lateral walls which are joined to and inside the composite box element (4) may have a height such that they do not touch the slab (1) but rest on the transverse walls (8) with which they interact with corrsponding mortise slits (7-9).
Products according to any one or more of the preceding claims, in which the lightening box elements (4-104-204) are predefined and prefixed below to the slab (1-2) of the prefabricated floor, in the stage of prefabrication of this product.
Products according to Claims 1 to 4, in which the lightening box elements (4-104-204-304) and/or other auxiliary parts which may contribute to the formation of the lightening box elements are partly prefixed to the slab (1-2) of the prefabricated floor, in the stage of prefabrication of this product, and are completed on site, before the floor finishing casting, with the joining to the remaining parts which make up and geometrically define the said lightening box elements, the whole in such a way as to contain the costs of production of the prefabricated floor and to enable the said prefabricated floors to be packed on top of each other with limited overall dimensions during storage and transport, since the parts of box elements previously associated with them can be contained within the spaces between the lattices (3) of the said prefabricated floors.
Products according to Claim 14, in which, in the areas of the slab (1) which have to carry the lightening modules, there are embedded, at the time of prefabrication of the floor, longitudinal strips, parallel and projecting (18-20), placed side by side and having upwardly open anchoring slits (19), or anchoring holes (21) provision being made to join the said strips, before the floor finishing casting, to the transverse walls (8-308), to which are then joined the longitudinal modules which make up and geometrically define the lightening box elements.
Products according to Claims 1 to 4, in which the lightening box elements (4-104-204-304) are defined as to their geometry and located on the slab (1) in the space between the lattices (13) directly at the place of installation of the floor, before the floor finishing casting.
Products according to any one or more of Claims 13 to 16, in which any suitable anchoring means are provided to enable the lightening box elements to be fixed to the slab (1) and/or to the lattices (3), to prevent the entry of the floor finishing casting into the said modules.
Products according to Claims 1 to 12, in which the lightening box element (204) has, for example, a transverse section with a fretted or sinusoidal profile, and its intermediate transverse walls (8) are provided with slits or apertures (15) next to the channel (14) of the said element which is upwardly open, this channel being provided below with apertures (17), the whole in such a way that at the time of prefabrication of the floor it is possible to form in this channel concrete or reinforced concrete beams (16) which are connected to the base slab (1-2) and which improve the mechanical characteristics of the floor.