WO2011077188A1

WO2011077188A1 - Machine and process for continuous manufacture of compact or self-draining slabs and slabs obtained thereby

Info

Publication number: WO2011077188A1
Application number: PCT/IB2009/055925
Authority: WO
Inventors: Max Canti
Original assignee: Max Canti
Priority date: 2009-12-23
Filing date: 2009-12-23
Publication date: 2011-06-30

Abstract

A process for continuously obtaining compact or self-draining slabs with particles (2) of various natures, having preselected particle sizes and mixed together and with a low viscosity and highly reactive two-component resin matrix (8), to form a mixture (M), comprising the steps of : layering dry particles by metering means into a substantially uniform layer on a carpet conveyor (4); containing said layer on said carpet conveyor; pouring said two-component resin matrix on said layer; introducing said carpet and mixture into continuous press means (PC) having an inlet with a predetermined gauge; recovering amounts of excess resin matrix accumulated against the gauge of the press means and flowing out in a direction opposite to the direction of the carpet conveyor (A); controlling the resin matrix outflow using sensor means (14,15) designed to decrease or increase the delivery rate; submitting the mixture to pressing and air removal actions, heating said mixture by heating means; cutting the continuous cured slab to size and picking it up from said carpet conveyor using pick-up means.

Description

MACHINE AND PROCESS FOR CONTINUOUS MANUFACTURE OF COMPACT OR SELF-DRAINING SLABS AND SLABS OBTAINED THEREBY Field of the invention

The invention relates to a machine and a process for continuous manufacture of compact or self-draining slabs and slabs obtained thereby, adapted to form conglomerate, self-draining or compact pavements made up of combined layers, using solid granules of any nature having a particle size from 0.5 to 4 millimeters and more in the mixture.

The continuously operating machine is unaffected by the fouling problems associated with the use of resins, and particularly two-component resins, that might hinder the manufacturing process; the machine also has a much higher throughput than those currently in use in conglomeration processes, because it can also use highly reactive two-component resins; furthermore, this machine may be also combined for successive processing, to obtain layered finished materials, possibly with layers of different natures and densities.

A further object is to continuously obtain self-draining or compact, i.e. non self-draining, wooden slabs, having an irregularly embossed surface, which might be designed for use in the field of phytohealth or in wellness centers, thermal centers and the like, to form barefoot walkways for "plantar reflexology", for both indoors and outdoors.

Another object is to continuously add a thermo-acoustic insulation layer to organic or inorganic composites, to be used as thin, possibly fragile claddings, or to add a light support layer in view of increasing the thickness and load bearing capacity of the slabs, to use them in the building of continuous ventilated facades and in any building application requiring a marked structural lightness, such as in shipbuilding or in elevators. MMAACCHHIINNEE AANNDD PPRROOCCEESSSS-- FFOORR CCOONNTTIINNUUOOUUSS *

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Field of the invention

Another object is to continuously add a thermo-acoustic insulation layer to organic or inorganic composites, to be used as thin, possibly fragile claddings, or to add a light support layer in view of increasing the thickness and load bearing capacity of the slabs, to use them in the building of continuous ventilated facades and in any building application requiring a marked structural lightness, such as in shipbuilding or in elevators.

1 A further object is to obtain a light composite that can be glued to a thin material to impart adequate thickness and load-bearing capacities thereto.

Yet another object of the invention is to obtain absorbent slabs, particularly water-absorbent slabs, sandwiched between two containing layers for use as a "reservoir", whenever accumulation and later gradual release of liquids, e.g. irrigation water, is required.

In a first aspect, the invention relates to a process of making continuous compact slabs as defined in claim 1.

In another aspect, the invention relates to a machine for continuously obtaining a compact slab as defined in claim 17. In a further aspect, the invention relates to continuous slabs as defined in claim 33.

Brief description of the drawings. Further features and advantages of the invention will appear more clearly upon reading of the detailed description of a machine for continuously obtaining compact or self-draining pavements and functional and decorative claddings having an insulation layer, as shown by way of illustration and without limitation in the accompanying drawings, in which:

Fig. 1 is a schematic side view of a machine for continuously obtaining compact or self-draining pavements and functional and decorative claddings having an insulation layer of the invention;

Fig. 2 is a schematic view of a first possible embodiment of a mixer apparatus for mixing particles;

Fig. 3 schematically shows a possible embodiment of a unit for feeding particles having a flexible metering screw;

Fig. 4 is a schematic view of a second possible embodiment of a mixer

2 apparatus as it feeds particles and a resin.

Embodiments of the invention Referring to Fig. 1 , a machine is shown for continuously obtaining compact or self-draining pavements and functional and decorative claddings having an insulation layer, briefly referred to as machine, where numeral 1 designates a hopper designed to contain solid particles 2, and having an adjustable opening 3.

The particles 2 are metered on a carpet conveyor 4 which has lateral retention edges 5, not shown in detail, and has a peel-apart film 6 unwound thereon from an unwinding device 7. A two-component polyurethane resin, designated by numeral 8, is delivered from a mixing head 9, which is maintained in transverse swinging motion on a beam 10 transverse to the direction of the carpet conveyor 4, to obtain a mixture " ". An additional peel-apart film 6' from another unwinding device 7' placed above the carpet conveyor 4 is deposited and coupled onto the mixture "M".

The conveyor and the mixture "M" sandwiched between the two peel-apart films 6 and 6', are fed under a continuous press "PC" that comprises a flexible steel belt 11 below the active conveying section of the carpet conveyor 4, which has a closed-loop configuration.

The belt , as it can be seen, runs on a number of rollers "R" coplanar with a rigid plate 16.

The continuous press "PC" further comprises an additional flexible steel belt 12, which is located in line with the rigid plate 16 above the active section of

3 the carpet conveyor 4.

The flexible steel belt 12 runs on a number of rollers or a rigid plate designated by numeral 17 and inclined in the feed direction, designated by the arrow "A".

Numeral 13 designates an excess of resin accumulated and flowing away in the area of the mixture "M" at the inlet of the continuous press "PC", where two photocells 14 and 15 detect and control it, by operating on the mixing heat 9 to decrease or increase the delivery rate of the two-component resin 8 therefrom.

Numerals 18 and 19 designates two press rolls which are designed to define the gauge, i.e. the thickness of the mixture "M", and are placed above and below the carpet conveyor 4.

Numeral 20 shows an additional unwinding device for a mesh 21 , typically a glass mesh, which is coupled by a bend wheel 22 to the layer of solid particles 2.

Such bend wheel 22 is required, when the mesh is adequately stretched, to retain any light particles that might otherwise float on the liquid two- component resin 8. Fig. 2 shows a mixer, designated by numeral 100, which is adapted to encapsulate particles in a long pot-life and high-viscosity two-component resin, before pouring them into the metering hopper 1.

The mixer 100 comprises a cylindrical container 101 rotating about a center axis 107, and having a double wall, with the inner wall 102 having a number of holes for communication with a vacuum chamber 103, whose wall has a disposable preformed elastic membrane 104 adhered thereto, and which is

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connected with vacuum creating means 108.

A rotating blade unit 105, with a braid 106 vacuum-adhered thereto, exerts a swinging upward and downward motion, and may be lifted when mixing is completed, to pour the mixture "M".

In the manufacture of self-draining slabs, the mixer 100 is operated by stopping the delivery of the low flow resin directly on the layers of wooden particles.

Fig. 3 shows a second possible embodiment of a mixer adapted for use in the invention, and designated by numeral 200.

The mixer 200 is fed with dry particles by means of a flexible metering screw 210 in the direction designated by arrow "Α .

Numeral 201 designates an exemplary embodiment of a cylindrical mixing chamber in which an inner wall 202 is formed of a layer of a release rubber compound.

Numeral 203 designates the opening through which the dry particles are introduced, which is fed by a flexible hose 204 with a worm 205, preferably made of a flexible plastic material, held therein. The flexible hose 204, as shown in Fig. 4, is connected to a bin 206 containing pre-mixed material "PM".

A motor unit 207, advantageously equipped with an inverter (not shown) rotates the flexible worm 205.

Still referring to Fig. 3, numeral 212 designates an inlet for receiving the two- component resin through a delivery pipe 213 having an outer concentric pipe

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214 fed with compressed air.

An end nozzle 215 produces a fan spray 216 and is oriented for the latter to impinge upon the falling granules 218, without fouling the receiving apertures.

A series of rotary mixing blades 219 are preferably driven by a hydraulic motor 220 and are appropriately mounted to a rotating shaft 222, driven by the motor 220, with two of them concurrently oriented and one countercurrently oriented, thereby causing the mixture to be intimately mixed and continuously fed towards an outlet 221.

According to the invention, in this application a selected mixture " " of particles is chosen, which has a particle size of more than one millimeter, with particles of up to about four millimeters and more; in certain cases, a lower particle size may be as low as about 0.5 mm.

Particles are dried, if needed, immediately before being fed by the metering hopper 1 , by having them pass through a series of magnetrons, i.e. magnetic heating appliances, with the advantage of providing hot particles, and thus accelerate curing of the resin matrix and hence afford energy savings; the removal of any residual moisture also allows deodorization of olive kernel wood particles, when used. The particles may be of many types, e.g. they may derive from food extraction processes, such as in the case of wooden particles deriving from extraction of oil from olives or other oilseeds; from the processing of coconuts, almonds and nuts, apricots, peaches, cherries, or consist of sterilized hard seeds, pine barks, cork processing waste.

Other particles may derive, for instance, from mechanically crushable woods, such as hemp stalk, known as "canapule" or Kenaf core ("Kenapulo").

6 Yet other particles may derive from minerals such as marbles, basalts, quartzes or processing wastes thereof, or ceramic industry wastes.

Other particles may be made of light plastic materials, possibly of foamed type, or expanded inorganic materials, such as expanded clay, cellular glass, expanded porous glass, vermiculite, perlite, pumice, etc.

The machine comprises a metering hopper 1 , continuously fed with loose particles in a dry state or previously encapsulated in a two-component resin, the latter being in turn continuously fed through a transverse opening 3 placed at the base and adjustable in height, a conveyor belt 4, or carpet conveyor, formed with a self-releasing material, and running below and flush with the transverse opening 3, which carries the uniform layer picked up through a continuous press "PC" downstream from the metering hopper 1.

Vertical side edges are also provided, which slide in closed loop arrangement and are held against the carpet conveyor 4, before, during and after passing through the continuous press "PC", which are designed for lateral retention of loose particles.

The continuous press "PC" may be of the type having flexible steel plates 11 and 12, in closed loop relation, in which the upper plate 12 is inclined in the feed direction "A" or having slat plates that can convey the mixture until it has completely cured.

The carpet conveyor 4 may also be formed of silicone rubber with semispherical irregular cavities formed therein to obtain a finished product with irregular semispherical bosses arranged all over the surface, to be used in walkways for wellness centers for plantar reflexology.

If the same carpet 4 with cavities is required to be used in combination with a deformable peel-apart film, to be interposed between it and the layer of

7 particles, the bottoms of the cavities have small holes and are connected with a vacuum chamber, preferably formed beneath the carpet, but not shown in the drawings. In order to obtain compact walking slabs, the dry particles are introduced into the metering hopper 1 which has a height-adjustable transverse opening 3 at the base, to set the thickness of the picked up final slabs flush with the carpet conveyor 4. The two-component resin is preferably of the low-viscosity, quick curing type, is delivered on the layered particles before entering the press "PC" through a mixing head 9 transversely swinging above the carpet 4; the low-viscosity resin matrix promptly fills the voids between the particles and, when first pressed under the belts of the continuous press "PC" flows out at the back, i.e. tends to accumulate in the direction opposite to the direction of the carpet conveyor, thereby forming the excess 13 as shown in Fig. 1.

When the out-flowing resin goes beyond a given retracted position of the bed of solid particles, the delivery unit, in this case the mixing head 9 automatically reduces the delivered amount until the out-flown amount close to entrance into the press "PC" is reabsorbed, and then restores the starting delivery condition.

The control may be ensured using two photocells 14 and 15 that can detect the color difference generated by the wet effect or by the addition of dyes to the resin, or using level sensors.

At the exit of the press "PC" a properly gauged, airless mixture "M" is obtained, which is enclosed, when needed, between two disposable peel- apart films 6 and 6', which may be laid by suitable unwinding apparatus 7 and 20, and between the lateral retention edges; such mixture "M" passes below a heat source, such as an infrared thermal wave, microwaves, or in

8 contact between two flexible hot plates, in closed loop arrangement.

Heat accelerates the curing process which, according to the degree of reactivity of the resin being used, may be carried out either completely or partially, with hardening being completed after the so-called "flying" cut, in the stack, if peel-apart films are provided.

As curing is completed, the peel-apart film 6 and 6', if any, may be removed and the surface may be ground to expose the conglomerated particles and highlight the decorative effect; then, they are polished by fine grinding and finally waxed.

As an alternative to a low-viscosity two-component resin, the same swinging mixer may deliver an inorganic two-component grout, consisting of aluminous cement in combination with lime milk, or a caustic magnesia grout in combination with magnesium chloride or sulfate, or other very quick-setting inorganic binders, also combined with blowing agents.

In the same machine, self-draining slabs will be obtained by feeding screened particles from 2 to 4 mm and more, previously mixed with a high- viscosity two-component resin that has a long pot-life, i.e. a long time of inertia before curing, into a mixer device, known as mixer 100, which is designed to prevent fouling by its inner wall being covered with a disposable elastic membrane 104.

The latter is caused to adhere by vacuum to the perforated walls connected to a dual chamber, renewable from time to time when required, which may consist of an appropriately preformed polyethylene bag; the inner mixing members are also covered by a braid 106 of polyethylene or other deformable material, which is caused to adhere by vacuum.

Alternatively, a continuous mixer 200 can be used, of the type that is typically

9 used in the cement mortar hydration, with certain appropriate changes, in which the dry material is fed by a flexible metering screw 210, affording it some translational motion above the metering hopper 1 , and the wet material is fed by a mixing-delivering head 212 having a Venturi tube at its outlet for atomizing the resin matrix on the falling particles, the mixing blades being oriented in series of two concurrently oriented blades and one counter- concurrently oriented blade, to enhance the mixing effect.

The cylindrical mixing chamber 201 and the rotating members 219 and 222 may be periodically quickly replaced for cleaning, with a clean chamber, no shutdown being required therefor.

The premixing feature affords the use of particles of less than one millimeter to provide resin savings, otherwise such premixing allows larger wood particles to be coated with as much curing resin as is strictly required for their conglomeration, without clogging the particle voids, so that the finished product maintains its self-draining features.

In the manufacture of self-draining slabs, the gauge of the press "PC", i.e. the space through which the bed of particles defined by the two belts 11 and 12 passes may be set to be slightly lower than the thickness of the bed of particles as formed by the metering hopper 1 , so that a lower compacting pressure will be exerted thereon, and the voids between particles will not be clogged with the resin matrix: hence, the binding action only occurs by contact of the particles that have been encapsulated before layering with the high-viscosity, long pot-life resin.

This material is thin in the case of compact finished products, but has a greater thickness in self-draining products, when wooden particles are used, and has a high penetration hardness, a very high resistance to walking and water, and may be conveniently used in renovation works, by binding or floating installation thereof on existing pavements without requiring any

10 demolition work; due to its high thermal inertia, it may be used in the replacement of carpeted and wood floorings, and is also applicable to bathrooms and kitchens: in the self-draining version, it can be used in swimming pool decks and walkways in parks and gardens or sidewalks or pedestrian precincts.

The machine of the invention can impart a load-bearing or technical thickness to prefabricated finished materials, such as thin parquet wood, terracotta cladding tiles, or thin natural cladding slabs, composite materials, possibly with embossed surfaces, which are placed in formworks that are continuously laid with a disposable spacer on the carpet conveyor where, as they move flush the metering hopper, they are layered with dry articles to be sprayed with the low-viscosity two-component resin, possibly of expanding type; or are layered with the same particles encapsulated in the high- viscosity resin; otherwise, the two-component resin mixing-delivering swinging device may be simply used to pour a known amount of expanding resin on the finished materials.

Alternatively, in the manufacture of thin compact slabs, the crystalline two- component matrix may be replaced with a polyurethane two-component elastomeric, thereby obtaining a highly walkable, flexible, incompressible material, whose lateral edges may be curved and raised over the vertical walls to obtain a skirting that ensures such hygiene features as to allow installation in hospitals, laboratories and food industry plants, as it allows seamless connection for vertical surface cladding.

The compact material obtained from wooden particles may be decorated by batch dyeing of the binding matrix, to highlight, after grinding, a natural wood effect in contrast with the colors of the binder, or may be coated with print or high surface resistance fire-proof paint, to look like a ceramic material, while maintaining the advantage of a high thermal inertia, to allow walking thereon without feeling cold. The same advantage of high thermal inertia, in combination with the possibility of obtaining an irregularly embossed surface, allows the wood particle-based compact material to be used in barefoot plantar reflexology walkways in wellness centers, thermal centers and the like, both in the indoor compact version and in the indoor and outdoor self-draining version.

By way of example, one machine having a useful width of 1300 mm can produce up to about 5000 square meters of panel each day, allowing 10,000 tons of kernel residues to be recycled in one year, considering a thickness of about 8 millimeters.

A first advantage of the process of the invention is its high throughput as compared with all processes in current use. Another advantage of such process as compared with other systems for obtaining compact conglomerate materials, is the possibility of using highly reactive two-component resin matrices that would not allow the components to be premixed and poured into a uniform layer. Another advantage is that no stops are required for cleaning the mixing instruments and the belts that convey the mixture to the location in which the uniform layer is formed.

Yet another advantage is the possibility of using very low-cost disposable peel-apart films, interleaved between the slabs, to allow stacking thereof downstream from the machine, even when curing is not completed, allowing curing to continue at a later time by the residual or ambient temperature, without affecting throughput. This possibility is particularly helpful when premixing involves the use of a high-viscosity, long pot-life resin matrix for encapsulating the particles in the formation of self-draining or non self-draining slabs.

12 Another advantage of the invention is the possibility of encapsulating the particles with a two-component curing resin while ensuring that the mixer is always clean, by removing vacuum-adhered disposable membranes or by quick replacement of the cylindrical mixing chamber of the continuous mixer.

A further advantage of the invention is the possibility of using the machine to form a first thin compact material, and later forming an additional thin self- draining material thereon to obtain, for instance, a wood pavement in which the walkway surface layer is reduced to the minimum thickness required for classification as a wood floor, whereas the underlying support layer is more inexpensive, due to its lower binding resin content and is also easy to lay using cement mortars, like a ceramic tile.

Another advantage of the invention is the possibility of using the same machine, equipped with a movable two-component resin mixing and delivering device, and a metering hopper for bulk materials, possibly encapsulated in a resin, to lay thin prefabricated elements on the carpet conveyor, in adjoining formworks and with disposable spacers, which elements possibly have an embossed surface, and are made of an organic or inorganic composite material, so that a thermo-acoustic insulation thickness may be added thereto, which is made of either an expanding two-component plastic material, or an organic or inorganic expanded bulk material in combination with a high-viscosity expanding two-component resin, to obtain functional and decorative cladding materials or as a disposable formwork for concrete casting, to provide the cladding, the insulation and the wall at the same time.

Yet another advantage in using the highly reactive resin matrix is that it allows considerable power savings.

This fulfills the object of the invention of providing a high-throughput machine and process for producing conglomerates, without any fouling of the means in use, which might hinder production and reduce the throughput.

Due to their high penetration and abrasion resistance, the materials so obtained, i.e. the slabs, can replace ceramic walkway and cladding materials and provide a dual advantage, i.e. an advantage for the biosphere, because when using olive kernels, huge amounts of carbon dioxide are fixed for a very long time, with no emission thereof that would be caused by fossil fuels used for ceramic baking, as well as the additional advantage of a high thermal inertia, allowing barefoot walking thereon with no cold sensation.

14

Claims

1) A process for continuously obtaining compact or self-draining slabs with particles of various natures, having preselected particle sizes and mixed together and with a low viscosity and highly reactive two-component resin matrix, to form a mixture, characterized in that it comprises the steps of:

- layering dry particles by metering means into a substantially uniform layer on a carpet conveyor;

- retaining said layer on said carpet conveyor;

- pouring said two-component resin matrix on said layer;

-introducing said carpet and mixture into continuous press means having an inlet with a predetermined gauge;

- recovering amounts of excess resin matrix accumulated against the gauge of the press means and flowing out in a direction opposite to the direction of the carpet conveyor;

- controlling the resin matrix outflow using sensor means designed to decrease or increase the delivery rate;

- submitting the mixture to pressing and air removal actions,

- heating said mixture by heating means;

- cutting the continuous cured slab to size and picking it up from said carpet conveyor using pick-up means.

2) A process as claimed in claim 1 , wherein a peel-apart film is placed above and below said layer.

3) A process as claimed in claim 1 , wherein continuous slabs of self-draining or non self-draining material are obtained by preparing first and second mixtures of particles respectively, the first mixture having a particle size from 2 to 4 mm and more, the second mixture having a particle size of 0.5 to 4 millimeters and more, characterized in that, before said layering, it comprises the steps of:

- encapsulating the particles in a high-viscosity, long pot-life two- component resin in mixing means, which resin is metered for conglomeration in such amounts as to prevent clogging of the voids between particles and to ensure that the slab so obtained still drains liquids; or

- alternatively encapsulate the particles in a high-viscosity, long pot-life two-component resin in such amounts as to fill the voids between particles; and

- pouring the encapsulated particles into said metering means, thereby forming said layer on the carpet conveyor;

- submitting the layer to said pressing action at low pressure, and binding the particles by mutual contact, or

- alternatively submitting the layer to the compacting action of the continuous press when it is not required to have self-draining features.

4) A process as claimed in any preceding claim, wherein in order to obtain compact or self-draining slabs embossed all over their surface, corresponding matrix cavities are formed on the carpet conveyor.

5) A process as claimed in any preceding claim, characterized in that a deformable peel-apart film is laid under vacuum on said carpet conveyor, so that it can be adhered to the surface of the carpet conveyor having such cavities.

6) A process as claimed in any preceding claim, characterized in that said particles are selected from the group of waste wood particles deriving from food extraction processes or else, that can be crushed into free-flowing dry particles or encapsulated in resin, such as olive kernels cleaned of any crumble part such as pulp residues, other oilseeds, coconut shells, nut and almond shells, peach, apricot, cherry kernels; materials containing sterilized hard seeds; pine barks; cork wastes; mechanically crushed woods, such as hemp stalks; inorganic materials deriving from minerals such as marble, basalt, quartz or processing wastes thereof; ceramic and brick processing wastes, metal waste fragments, light organic or inorganic expanded

16 materials, such as plastic materials, recycled rubber, expanded clay, cellular glass, expanded porous glass, perlite, vermiculite, pumice.

7) A process as claimed in any preceding claim, wherein compact, non self- draining slabs are obtained by:

- using particles of various natures with particle sizes from 1 to 4 mm and more;

- continuously pouring said particles on an even-thickness moving bed of dry particles of a low-viscosity, two-component fluid material, which quickly cures also at ambient temperature,

- mixing before said pouring;

said fluid material being either organic, such as a polyurethane, epoxy, alphatic, etc. material, or inorganic, such as caustic magnesia in combination with magnesium chloride or sulfate, aluminous clinker, in combination with lime milk, aluminous clinker in combination with calcium sulfate, hydrated and whether in combination with expanding agents or not.

8) A process as claimed in any preceding claim, wherein self-draining slabs are obtained by:

- using a two-component fluid material that exhibits high-viscosity, long pot-life at ambient temperature, and quick curing at high temperatures;

- encapsulating said particles before pouring them into said metering means. 9) A process as claimed in any preceding claim, wherein the values of compaction pressure by said continuous press means may be selected between a low pressure and a high pressure to obtain self-draining or non self-draining slabs respectively. 10) A process as claimed in any preceding claim, wherein in the manufacture of slabs from olive kernel particles, before said layering by said metering means, said particles are deodorized and dried by a heat treatment.

17 11) A process as claimed in any preceding claim, characterized in that said resin matrix comprises dyeing pigments.

12) A process as claimed in any preceding claim, characterized in that it provides at least surface abrasion/grinding of said compact slabs, to obtain a decorative effect.

13) A process as claimed in any claim, characterized in that it provides:

- a first thin compact slab layer;

- a second self-draining support slab layer, laid upon said first layer, using

- for said first layer, first delivery means for directly delivering low-viscosity resin on the bed of dry particles and,

- for said second layer laid directly upon said first layer, second delivery means for encapsulating the particles in the high-viscosity resin.

14) A process as claimed in claim 13, wherein said first layer comprises a walkable layer of a pavement and said second layer comprises a support layer for said first layer. 15) A process as claimed in any preceding claim, wherein said resin matrix is selected as either a rigid or an elastic resin matrix, to form flexible or rigid thin compact slabs respectively.

16) A process as claimed in claim 1 , wherein a ground compact slab is decorated by laying print or protective paint thereon.

17) A machine for continuously obtaining a compact slab from granules having a selected grain size, characterized in that it comprises:

- metering means (1) for metering dry particles into a layer (M) of substantially constant thickness;

- conveyor means in the form of a carpet conveyor (4) on which said layer (M) is formed;

18 - lateral retention means for retaining said layer, maintained against said carpet conveyor (4);

- delivery means (9) for delivering a two-component resin matrix (8) on said layer (M), equipped with delivery control means;

- sensor means (14, 15) designed to detect any excess of said resin matrix ((M) generated in a direction opposite to a direction (A) of said carpet conveyor (4);

- continuous press means (PC) through which the carpet conveyor (4) moves ;

- means for cutting the conglomerate slabs to size.

18) A machine as claimed in claim 17, wherein said continuous press means (PC) include heating means. 19) A machine as claimed in claim 17, wherein it further comprises unwinding means (7, 7') for unwinding peel-apart films or films to be embedded (6, 6'), that can be placed either above or below said layer (M).

20) A machine as claimed in claim 17, wherein it optionally comprises additional unwinding means (20) for at least one mesh (21) for retaining particles floating on said resin matrix (8) in liquid state.

21) A machine as claimed in claim 17, wherein said carpet conveyor (4) has a surface with cavities connected to vacuum means, through connection holes formed in said cavities.

22) A machine as claimed in claim 17, wherein it comprises means for picking up and stacking conglomerate slabs. 23) A machine as claimed in claim 17, characterized in that said delivery means are replaced by mixer means (100; 200) for mixing said dry particles with said resin matrix, which are arranged between said metering means (1)

19 and said carpet conveyor (4), and are designed to encapsulate said particles in said resin matrix, said mixer means (100; 200) having a feed opening and a discharge opening placed above said carpet conveyor (4). 24) A machine as claimed in claim 23 wherein said mixer means comprise:

- a cylinder (101) that rotates about its longitudinal axis (107) and is open at one end;

- a vacuum chamber (103) defined in said rotating cylinder (101) and having an inner wall (102) with holes of selected sizes;

- a preformed release membrane (104) stretched on said inner wall (102);

- a hollow shaft (105) rotatably supported in said rotating cylinder (101) and having a series of radially directed hollow mixing blades (105'), which are put in communication with suction means, through holes formed thereon;

- a disposable elastic or deformable braid (106) that covers said rotating shaft (105) and mixing blades (105'),

said release membrane (104) and braid ( 06) being cyclically replaceable.

25) A machine as claimed in claim 24, wherein said rotating shaft (105) is removably supported in said rotating cylinder (101) and is capable of axial swinging motion during mixing.

26) A machine as claimed in claims 17 and 23 wherein said mixer means comprise:

- a continuous mixer apparatus (200) comprising a removable cylindrical mixing chamber (201),

- a flexible metering screw (210) for feeding at variable flow rates the solid part of said mixture comprising dry particles into said mixing chamber (201);

- a mixing head (212) having a Venturi tube passage designed for feeding a liquid part of said mixture and for causing a spray fan (216) of two- component resin to impinge upon said solid part;

- a plurality of mixing blades (219) associated with a rotating shaft (222) and arranged in series of two concurrently oriented blades and one

20 countercurrently oriented blade.

27) A machine as claimed in any claim from 24 to 26, wherein means are provided for drying the dry particles before introducing them into said metering means (1) or said mixer means (100; 200).

28) A machine as claimed in any claim from 17 to 27, wherein said layer comprises a bed of loose particles. 29) A machine as claimed in any claim from 17 to 27, wherein said layer comprises loose particles pre-encapsulated in a high-viscosity, long pot-life resin.

30) A machine as claimed in any claim from 17 to 27, wherein said layer comprises:

- a prefabricated element;

- a layer of foamed plastic material cast upon said prefabricated element.

31) A machine as claimed in any claim from 17 to 27, wherein said layer comprises:

- a prefabricated element;

- a layer of loose particles deposited on said prefabricated element and

- and expanding two-component resin sprayed in said layer of loose particles.

32) A machine as claimed in claim 30 or 31 , wherein said prefabricated element comprises at least one metal slab.

33) Continuous slabs obtainable by a process and a machine as claimed in one or more of the preceding claims, characterized in that they alternatively have a self-draining or non self-draining structure.

21 34) Continuous slabs as claimed in claim 33, wherein at least one surface of said slabs has regularly/irregularly arranged bosses.

35) Continuous slabs as claimed in claim 32 or 33, wherein said continuous slabs are either rigid or flexible.

36) Continuous slabs as claimed in one or more of claims 32 to 34, wherein they include mixtures of two-component resin matrices and dry particles or mixtures of two-component grouts and quick inorganic binder, optionally combined with expanding agents.

37) Continuous slabs as claimed in any claim from 32 to 35, wherein said slabs have at least first and second layers in superimposed relation, whereof said first layer, defined as the upper layer, has an exposed surface and said second layer, defined as the lower layer, has a laying surface, said first layer being compact and forming a walkway layer comprising aliphatic resin matrices, said second layer being made of materials of different nature, thereby imparting technical properties to said slabs, such as heat and/or sound insulation.

38) Continuous slabs as claimed in one or more of claims 32 to 35, characterized in that they comprise a layer of hemp stalk particles capable of absorbing and holding water, with a layer of a one-component isocyanate material deposited thereon, replacing said two-component polyurethane resin.

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