EP1260334B1 - Process and device for producing building components - Google Patents

Abstract

The procedure consists of filling a multi-compartment mould (14) with a mixture of plaster, sand and water, and compressing the mixture slowly to compact it and remove surplus water and air, reducing its volume to a minimum level. The pressure applied at a low level for a long course, followed by a higher lever for a short course, reaching a maximum of about 10 MPa. The mould is removed simultaneously from all the blocks, which measure about 25 x 50 x 10 cm each and are then allowed to set on their own.

Description

The present invention relates to a method and a device for manufacturing building elements, in particular for interior walls of buildings, from a mixture of plaster, a load such as sand and water.

He is already known, for example by EP-A-0619773 , fabricating building blocks from a mixture of plaster, a filler such as sand and water, by pressure molding the mixture for a time sufficient to hydrate the plaster under pressure and obtain thus a densification of its crystal lattice.

The building blocks thus obtained have excellent mechanical characteristics, comparable to those of building stones, they can be used in construction at the outlet of the molds without prior drying, and they have a very high dimensional accuracy that allows them to be mounted on one another. on others without joints.

In this known method, the mixture of plaster, sand and water is slowly compressed and left under pressure in the mold during the setting of plaster, this duration being in general of several minutes, then the mold is opened and the block is demolded to be stored or used in construction. It is necessary for the demolding to exert a relatively strong thrust on the block, due to the relatively high pressure that the block applies to the walls of the mold, resulting from the expansion of the plaster inside the mold. Sometimes, if the block is left in the mold too long, the expansion of the plaster is completed and it is impossible to unmould the block, if one does not have a sufficiently powerful hydraulic cylinder. For these reasons, it is necessary to demold the blocks for example two-thirds of the expansion of the plaster, which requires knowing the duration of the maximum expansion of the plaster with sufficient precision, either to equip the machine. manufacturing very powerful cylinders, so relatively very expensive.

In addition, the setting of the plaster inside the mold results in immobilization of the mold for a relatively long period, which requires having a large number of molds or supporting relatively low production rates.

The document EP-A-0184551 discloses a device for molding building blocks from a plaster mixture comprising a mold with rigid and non-deformable side walls and with upper and lower openings receiving trays displaceable in translation inside the mold, compression means of the mixing in the mold and means for demolding the building blocks comprising support means on the upper faces of said blocks in the mold compartments and means for translating the mold parallel to said blocks. This device allows the execution of a method of manufacturing building blocks from a mixture of plaster, a load such as sand and water, the amount of water in the mixture being slightly greater than that necessary to obtain the maximum compactness of the mixture, the process of slowly compressing this mixture in the multi-compartment mold to compact it and to evacuate the excess water and the air contained and reduce its volume substantially to a minimum minimum value.

The present invention is intended in particular to provide a simple, satisfactory, effective and cheap solution to these problems, particularly in the case of the manufacture of building elements for use inside a building.

It proposes, for this purpose, a method of manufacturing building elements, according to the features of claim 1.

• on peut démouler les éléments de construction dès que leur compression dans le moule leur a donné une cohésion interne suffisante, c'est-à-dire après un temps de l'ordre de 30 secondes au maximum,
• on peut mouler et démouler simultanément plusieurs éléments de construction, ce qui augmente la cadence de fabrication,
• le démoulage des éléments s'effectue avant la prise du plâtre, donc pratiquement sans expansion volumique du plâtre et peut être réalisé sans effort avec un vérin hydraulique relativement peu puissant,
• la compression du mélange dans le moule permet de conférer aux éléments de construction des caractéristiques mécaniques relativement élevées, très largement supérieures aux minima imposés, et une bonne précision dimensionnelle.

The method according to the invention has a certain number of advantages over the known technique:

• the building elements can be demolded as soon as their compression in the mold has given them sufficient internal cohesion, that is to say after a time of the order of 30 seconds maximum,
• several construction elements can be molded and demolded simultaneously, which increases the production rate,
• the demolding of the elements takes place before the setting of the plaster, so practically without volume expansion of the plaster and can be achieved without effort with a relatively weak hydraulic cylinder,
• the compression of the mixture in the mold makes it possible to give the construction elements relatively high mechanical characteristics, very much greater than the imposed minima, and a good dimensional accuracy.

According to another characteristic of the process according to the invention, the maximum final pressure applied to the mixture in the mold is of the order of 10 MPa.

The construction elements thus manufactured have a compressive strength of at least 15 MPa and is typically about 25 to 30 MPa.

These elements can be used to make load-bearing partitions.

Advantageously, this method also consists of using a delayed or relatively slow-setting plaster, and mixing it uniformly and progressively with the amount of water mentioned above.

Thanks to the slow or delayed setting of this plaster, it is possible to mix without being obliged to do it very quickly, which allows to mix more evenly plaster, sand and water.

In general, the amount of filler in the above mixture may vary between about 30 and 80%, by weight.

Advantageously, the compressed mixture in the mold contains hydrophobic agents such as silicones, for example.

Typically, the construction elements thus produced are planar elements for interior walls, for example having dimensions of the order of 25 cm × 50 cm × 10 cm, but it is of course possible to produce, by execution of the method according to the invention, building elements. having all desired shapes and sizes.

The invention also proposes a device for carrying out this method, according to the features of claim 8.

This device makes it possible to simultaneously mold and demold easily a plurality of elements, with a single mold.

According to another characteristic of this device, the compression means comprise means for moving the upper plate and / or the lower plate inside parts of the mold which are devoid of internal partitions.

These compression means may be independent of the support means used for demolding, or include the same means as these support means.

• la figure 1 est une vue schématique en coupe axiale d'un dispositif selon l'invention, le moule étant représenté ouvert ;
• la figure 2 est une vue correspondant à la figure 1, mais représente le moule fermé ;
• la figure 3 est une vue schématique de dessus du moule ;
• la figure 4 est une vue semblable aux figures 1 et 2, mais représente le dispositif au cours du démoulage des éléments de construction.

The invention will be better understood and other characteristics, details and advantages thereof will appear more clearly on reading the description which follows, given by way of example with reference to the appended drawings in which:

• the figure 1 is a schematic view in axial section of a device according to the invention, the mold being shown open;
• the figure 2 is a view corresponding to the figure 1 but represents the closed mold;
• the figure 3 is a schematic top view of the mold;
• the figure 4 is a view similar to Figures 1 and 2 but represents the device during the demolding of the building elements.

The manufacturing device according to the invention is intended in particular to be used with a hydraulic press, comprising at least one hydraulic cylinder and preferably two axially aligned hydraulic cylinders.

In the example shown in Figures 1, 2 and 3 , the press comprises an upper hydraulic cylinder 10 and a lower hydraulic cylinder 12 with vertical action, which are axially aligned and between which is mounted the manufacturing mold of the construction elements.

This mold 14 is of rectangular parallelepipedal general shape and comprises side walls 16 which are rigid and dimensionally stable. Its upper and lower ends 18, 20, respectively, are open and receive substantially horizontal upper closure plates 22 and lower 24 that are displaceable in vertical translation inside the mold 14 with a small clearance with respect to the side walls of the mold.

The internal space of the mold 14 is divided into a plurality of identical compartments 26 by internal partitions 28 which extend vertically between the side walls 16 of the mold and which are fixedly mounted on these walls. The internal partitions 28 have a height less than that of the mold 14 and terminate at a distance from the open ends 18, 20 of the mold, forming stops which limit the strokes of the trays 22 and 24 inside the mold.

The upper plate 22 can be fixed or hooked on a plate 30 displaceable in vertical translation by the upper cylinder 10, and likewise the lower plate 24 is fixed or hooked on a plate 32 displaceable in vertical translation by the lower cylinder 16.

As shown, the lower part of the mold 14 which extends under the internal partitions 28 may be formed by a tubular element 34 independent of the upper part of the mold or may alternatively be in one piece with this upper part .

• initialement, l'extrémité inférieure 20 du moule est fermée par le plateau 24 qui est engagé sur une très faible hauteur, par exemple un centimètre environ, à l'intérieur de la partie inférieure 34 du moule, et le plateau supérieur 22 est retiré ou écarté de l'ouverture supérieure du moule. Un mélange de plâtre, d'une charge telle que du sable et d'eau est ensuite versé à l'intérieur du moule 14, pour remplir les compartiments 26 et recouvrir les bords supérieurs des cloisons 28.

The method of manufacturing building elements according to the invention by means of this device is as follows:

• initially, the lower end 20 of the mold is closed by the plate 24 which is engaged on a very small height, for example about one centimeter, inside the lower part 34 of the mold, and the upper plate 22 is removed or away from the upper opening of the mold. A mixture of plaster, a filler such as sand and water is then poured into the mold 14, to fill the compartments 26 and to cover the upper edges of the partitions 28.

This mixture comprises about 30 to about 80% by weight of filler and about 70 to about 20% by weight of plaster, the amount of water being slightly greater, for example by a few percent, than that required for maximum density. of the mixture (optimum Proctor). Depending on the granulometry of the filler and the plaster, the amount of water can vary between 1.5 and 1.9 liters in the case of a mixture comprising about 6 kilos of sand and 4 kilos of plaster.

Advantageously, a delayed or slow setting plaster can be used to provide sufficient time to mix the sand, plaster and water substantially uniformly before the plaster begins to set.

A small amount of hydrophobic products, such as silicones, may be added to the mixture in a proportion of about 1 to 5 per thousand of the weight of water used.

The homogeneous mixture of plaster, sand and water is difficult, if not impossible, if you just pour a suitable amount of water on a mixture of plaster and sand. You must either spray the water on the mixture of plaster and sand when this mixture falls in the mold, or spray the water on a mixture of plaster and sand in a kneader designed for this purpose, as described for example in WO 00/30819 . Otherwise, the plaster, sand and water form a compact and sticky block in which the water is poorly distributed and that we can not mold properly, even by compressing strongly.

When a quantity of the mixture corresponding to the internal volume of the mold has been poured into the mold, this mixture is slowly crushed and compressed in the mold to obtain a maximum density resulting from an evacuation of the excess water and the air contained in the mixture, which can escape by the clearances between the plates 22 and 24 and the side walls of the mold, these games being weak, of the order of one tenth of a millimeter or less.

For this compression and compression, depending on the conditions of filling of the mold 14, it is possible either to move only the lower plate 24 upwardly to bring it into abutment with the lower edges of the partitions 28, or to simultaneously move the trays 22 and 24 towards each other inside the mold.

• suppression des plans de clivage qui pourraient résulter de l'application d'une pression unidirectionnelle,
• bon mouillage de la totalité de la surface des grains de la charge,
• déplacement de ces grains et organisation de leur disposition pour une compacité maximale.

When the elements to be manufactured have a height of 25 centimeters for a length of 50 centimeters and a thickness of 10 centimeters, for example, the total displacement travel of the trays 22 and 24 for packing and compression of the mixture in the mold may be as follows. first fifteen centimeters, the pressure applied to the mixture by the or plates 22, 24 being relatively low. Then on a stroke of a few centimeters, the pressure increases gradually to a value for example between 5 and 10 MPa for which we arrive at neighborhood of the maximum compactness of the mixture in the mold. In general, the slow compression of the mixture is exerted for a time necessary for the progressive evacuation of excess water and air and has the additional effect of creating inside the mixture an omnidirectional hydrostatic pressure which has several advantages:

• removal of cleavage planes that could result from the application of unidirectional pressure,
• good wetting of the entire grain surface of the load,
• moving these grains and arranging them for maximum compactness.

This latter advantage is increased when finer grains are added to the mixture than those normally used.

The volume of water used in the mixture of plaster, filler and water to obtain the maximum compactness (optimum Proctor) corresponds to the volume of water necessary for the hydration of the plaster contained in this mixture and its transformation into gypsum .

The duration of this compression phase may vary from a few seconds to about 15 to 20 seconds, depending on the particle size characteristics of the materials used.

At the end of this compression, the plates 22 and 24 are in the positions shown in FIG. figure 2 and are substantially in abutment with the internal partitions 28.

The elements 36 which are formed by the compacted and compressed mixture in the compartments 26 of the mold are then demolded.

For this, the upper plate 22 is lifted and, as shown in FIG. figure 4 , we bring means support 40 on the upper faces of the elements 36 to maintain these elements in place when moving the mold 14 in vertical translation upwardly to completely clear the molded elements 36 of the side walls 16 and internal partitions 28 of the mold.

When this is done, the support means 40 are moved aside and the molded elements 36 are removed from the lower plate 24.

As shown schematically in figure 4 , the support means 40 are carried by vertical rods 42 connected at their upper ends to means 44 for support and maneuvering.

In this embodiment, the means 40, 42, 44 for holding the molded elements 36 in place during their demolding are independent of the means 10, 22, 30 for compressing the mixture in the mold.

As a variant, these means can be confused, especially when provision is made for separate means for compressing the mixture in the various compartments 26 of the mold. In particular, the rods 42 may be piston rods of hydraulic cylinders and the support means 40 are then movable by these piston rods vertically over a distance corresponding to the end of the compression of the mixture in the mold. This can be done by providing a hydraulic cylinder per compartment.

In all cases, the rods 42 must have a height allowing vertical translation of the mold 14 and internal partitions 28 sufficient for demolding the elements 36.

These elements can be used in construction very shortly after demolding, as soon as the setting of the plaster is completed, which can take from a few minutes to a few tens of minutes. depending on the temperature and characteristics of the materials used.

When the compressed mixture in the mold contains the aforementioned hydrophobic agents, the elements obtained can be used in bathrooms, kitchens, laundries, etc., because of their hydrophobic nature. They can also be used outdoors.

Of course, the invention is not limited to the embodiment described and shown and applies to the manufacture of building elements having various shapes and dimensions.

Claims (8)

1. A method for producing building components, in particular panels for interior walls of buildings, from a mixture of plaster, of a filler such as sand and water, the amount of water in the mixture being slightly larger than that required for obtaining maximum compactness of the mixture, this method consisting of slowly compressing this mixture in a mould (14) with multiple compartments (26) for packing it and for evacuating excess water and the air contained in the mixture and reducing its volume substantially up to a minimum value, further characterized in that the components (36) are simultaneously removed from the mould by vertical translation of the mould with multiple compartments relatively to the components (36) maintained immobile and setting of the plaster is left to occur in the components (36) outside the mould (14).
2. The method according to claim 1, characterized in that it consist of carrying out compression of the mixture in the mould (14), first of all with a relatively low pressure over a relatively large stroke, and then with a stronger pressure over a relatively small stroke.
3. The method according to claim 1 or 2, characterized in that the maximum final pressure applied to the mixture in the mould is of the order of 10 MPa.
4. The method according to any of the preceding claims, characterized in that it consists of using a retarded plaster or one with relatively slow setting and of mixing it substantially in a uniform manner with the aforementioned amount of water.
5. The method according to any of the preceding claims, characterized in that the amount of filler in the mixture is comprised between about 30 and 80% by weight.
6. The method according to any of the preceding claims, characterized in that the compressed mixture in the mould contains hydrophobic agents such as silicones for example.
7. The method according to any of the preceding claims, characterized in that the components (36) are panels with dimensions of the order of 25cm x 50cm x 10cm.
8. A device for performing the method described in any of the preceding claims, comprising a mould (14) with rigid and undeformable sidewalls (16) and with upper (18) and lower (20) apertures receiving trays (22, 24) translationally displaceable inside the mould, means for compressing the mixture in the mould and means for removing from the mould said building components (36) comprising means (40) for bearing upon the upper faces of the components (36) in the compartments of the mould and means for translating the mould parallel to said components (36), characterized in that the mould (14) comprises internal partitions (28) delimiting moulding compartments of said components (36), fixedly mounted on the sidewalls (16).

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