BACKGROUND ART In the flooring and wall facing field, the weight of the product to be laid is known to be of fundamental importance.

In the particular case of marble floorings and facings, this weight is very high, and negatively affects the structural calculations and transport and installation costs.

In particular, in constructing large-area floors and large buildings, the weight factor often prevents marble facings being used.

The problem can be viewed in terms of product thickness. In this respect, because of poor material resilience, marble slabs can be cut and machined down to an achieved limiting thickness of fifteen-twenty millimetres, below which the slabs tend to crumble during machining or subsequent finishing operations (polishing, etc.).

In addition, even if lesser thicknesses are achieved by the use of sophisticated machine tools, the slabs obtained would be unusable because of their considerable fragility.

To partly overcome this problem, the current technology of the sector provides for the use of slabs formed from marble grit mixed with epoxy resin and other lighter materials.

Besides not presenting the considerable esteem and salubriousness of natural marble, this solution often requires the use of special binders to ensure their adherence to the support on which they are to be laid.

An object of the present invention is to provide a slab-like marble product which presents weight characteristics less than those currently attainable by the marble slabs currently used.

Another object is to provide a slab-like marble product which presents a thickness considerably less than that of currently used common marble slabs.

Another object is to define a slab-like marble product as aforestated which, by virtue of increased strength, can be machined and handled more easily than currently used marble slabs.

DISCLOSURE OF THE INVENTION These and further objects will be seen to have been attained on reading the following detailed description illustrating the method for obtaining a marble composite slab-like product, and the product obtained, the inventive aspects of which are defined in the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated by way of non-limiting example in the accompanying drawings and in the examples described hereinafter.

In the drawings: Figure 1 is a section through the composite slab-like product obtained.

Figure 2 is an exploded perspective view of the composite slab-like product obtained.

BEST MODE FOR CARRYING OUR THE INVENTION

With reference to the aforesaid figures, some embodiments of the method of the present invention are given hereinafter.

Example one Two rectangular slabs 1A and 1 B of Bardiglio marble are used having a thickness 5 of twenty millimetres and side dimensions of three hundred by four hundred millimetres. On one face of one of these there is applied a layer 2 of conventional two-component epoxy resin (for example the product known by the name of Araldite of Ciba-Geigy) by spreading. A piece of mesh fabric 3 (glass fibre net), also conventional, is laid on the resin layer 2. This fabric piece has dimensions virtually identical to those of the slabs and a thickness of about three tenths of a millimetre. The weft of the mesh fabric 3 presents an indicative preferential pitch of two millimetres. The total thickness of the combined resin+fabric is about one millimetre. The second slab 1 B is then placed on the combined resin+fabric, exerting a moderate pressure. This produces a compression of the binder 2, causing it to seep through the apertures of the mesh fabric 3, and reach the lower surface of the slab 1 B (i. e. a sort of imbibition).

After polymerization of the resin, which is preferably made to take place at ambient temperature (within the temperature limits defined by the manufacturers of the resin used), the two slabs 1A and 1 B, and the interposed mesh fabric, are found to be rigidly joined together to form a single composite 4. The composite 4 is then mechanically machined by usual machine tools (e. g. cutting discs or cup grinding wheels) to reduce its thickness by removing material. This machining is performed on both faces until a thickness 6 of six millimetres is achieved, to obtain a slab-like

product of low weight but of high strength, as required by the present invention. The slab-like product can then be polished or treated in traditional manner, this not forming part of the present invention.

Example two Two rectangular slabs 1A and 1 B, of which one slab 1A is of Botticino marble and the other slab 1 B is of Bianco Carrara marble (hence different marbles) are used. These slabs both have a thickness 5 of fifteen millimetres and side dimensions of eight hundred by four hundred millimetres. On one face of one of these there is applied a layer 2 of conventional two-component epoxy resin (for example the product known by the name of Allbond of Bacon Industries) by spreading. A piece of mesh fabric 3 (carbon fibre mesh), also conventional, is laid on the resin layer 2. This fabric piece has dimensions virtually identical to those of the slabs and a thickness of about two tenths of a millimetre. The weft of the mesh fabric 3 presents an indicative preferential pitch of two millimetres.

The total thickness of the combined resin+fabric is about one millimetre.

The second slab 1 B is then placed on the combined resin+fabric, exerting a moderate pressure. This produces a compression of the binder 2, causing it to seep through the apertures of the mesh fabric 3, and reach the lower surface of the slab 1 B (i. e. a sort of imbibition). After polymerization of the resin, the two slabs 1A and 1 B, and the interposed mesh fabric, are found to be rigidly joined together to form a single composite 4. The composite 4 is then mechanically machined by usual machine tools (e. g. cutting discs or cup grinding wheels) to reduce its thickness by removing material. This machining is performed on both

faces until a thickness 6 of six and a half millimetres is achieved, to obtain a slab-like product of low weight but of high strength, as required by the present invention. In the present example the slab-like product obtained is then polished on both faces, such as to present two different appearances which make it suitable, for example, for partition walls.

Example three Utilizing the aforedescribed method, a composite slab-like product was produced having a thickness 6 of three and a half millimetres, starting from slabs 1A, IS both of Bianco Statuario Venato marble and side dimensions of 1200 x 600 mm, with a thickness of two and a half millimetres.

Example four Utilizing the method described in the preceding examples and using a slab of Nero Assoluto marble of side dimensions three hundred by two hundred millimetres and a thickness 5 of twenty-three tenths of a millimetre, a glass slab 1 B of twenty-three tenths of a millimetre in thickness, and using two- component polyurethane adhesive (for example LitoElastic PU34 of LITOKOL) and glass fibre fabric 3, a marble/glass slab-like product having a thickness 6 of sixty-six tenths of a millimetre is obtained after mechanically machining the side of the marble to remove material.

Example five The already described method is utilized, but using as adhesive an acrylic- based paste filled with inert microbeads (for example Litoacril LA201 of LITOKOL).

The mesh fabric 3 ideally consists of glass fibre strands; in this respect, glass has been found to be the most versatile material for the different varieties of marble. Notwithstanding this, for certain particular types of marble it may be preferable to use fibres of materials other than glass, such as mineral fibres (for example carbon) or synthetic fibres (for example Kevlar).

In addition to collaborating with the resin to ensure good adherence between the slabs 1A, 1 B, the mesh fabric 3 increases the strength of the composite slab 4, to considerably reduce the risk of breakage or chipping during machining, and the resultant scrap.

The results of tests carried out have shown that a composite marble slab- like product of six and a half millimetres thickness, obtained by the method of the present invention, presents strength characteristics of three-four times those of a normal twenty millimetre thick slab of the same type of marble.

Moreover, as a consequence of the small thickness, the product of the present invention has a weight much less than that of common marble floor slabs, so achieving easier handling during transport and installation, and enabling it to be also used in those cases in which the floor weight must necessarily to be low.

A further advantage of the product of the present invention is its impermeability, ensured by the presence of the epoxy resin layer 2, which dispenses with the need for the common chemical anti-absorption treatments carried out on usual marble floors. This ensures that the

composite marble slab-like product obtained by the present method is totally salubrious and natural.

Lastly, said advantages result in a saving in transport ; laying and other costs, making the composite marble slab-like product 4 competitive both with respect to average quality flooring and to products of high esteem.

Other tests have been carried out which demonstrate the capability of obtaining composite slab-like products between five and seven millimetres thick, with mesh fabrics preferably of between two and five tenths of a millimetre thickness, and a combined thickness of resin plus mesh fabric of between five and fifteen tenths of a millimetre.

Instead of one of the two marble slabs, it is possible to use (in addition to the glass already described) other slab materials, such as wood or wood- based materials incorporating a polyurethane resin binder (plywood, masonite, chipboard, etc.), ceramic, metal, etc.

The adhesive compound used is preferably of epoxy type. However in certain cases it can be appropriate to use other different adhesives, such as acrylic, polyurethane etc., possibly filled with microbeads (for example glass beads) to optimize adhesion in relation to any material difference between the two slabs and to ensure satisfactory final strength of the layer 2.