FR2824772A1 - Interior wall building block manufacturing procedure and equipment uses mould with compartments in which mixture is compressed slowly - 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

Method and device for manufacturing construction elements La

  The present invention relates to a method and a device for manufacturing construction elements, in particular elements for interior walls of buildings, from a mixture of plaster, a

filler such as sand and water.

  It is already known, for example from EP-A-0619773, lo to manufacture building blocks from a mixture of plaster, of a filler such as sand and water, by pressure molding of this mixture during a hardness sufficient to achieve hydration under pressure of the plaster and thus obtain 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 exit of the molds without previous drying, and they have a very high dimensional precision which makes it possible to assemble them.

on top of each other without joints.

  In this known process, the mixture of plaster, sand and water is compressed slowly and left under pressure in the mold during the setting of plaster, this duration generally being several minutes, then the mold is opened and the block is unmolded for storage or use in construction. It is necessary for demolding to exert a relatively strong push on the block, due to the relatively high pressure that the block applies to the walls of the mold, and which results from the expansion of the plaster inside the mold. It sometimes happens, if the block is left too long in the mold, the expansion of the plaster is finished and it is impossible to unmold the block, if one does not have a sufficiently powerful hydraulic cylinder. For these reasons, one is led either to demould 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, or to equip the machine with manufacture of very powerful cylinders, therefore

relatively very expensive.

  o In addition, the setting of the plaster inside the mold results in an immobi l i sat ion of the mold for a relatively long period, which requires having a large number of molds or supporting relatively high production rates.

low.

  The object of the present invention is in particular to provide a simple, satisfactory, effective and inexpensive solution to these problems, in particular in the case of the manufacture of construction elements intended to be used for

inside a building.

  To this end, it proposes a method of manufacturing construction elements, such as for example panels for interior walls of buildings, from a mixture of plaster, a filler such as sand and water. , the amount of water in the mixture being slightly greater than that necessary for the hydration of the plaster, this process being characterized in that it consists in compressing this mixture in a mold with multiple compartments to pack it and to evacuate the excess water and the air contained in the mixture and reduce its volume appreciably to a minimum value, then simultaneously unmold the elements contained in the mold compartments and leave the pr se se of the

  plaster to operate outside the mold.

  The method according to the invention has a certain number of advantages compared to the known technique: - the construction elements can be removed from the mold 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 elements are demolded before setting the plaster, therefore practically without volume expansion of the plaster and can be carried out with a relatively weak hydraulic cylinder i5, - the compression of the mixture in the mold makes it possible to give the construction elements relatively high mechanical characteristics, very much higher than the minima imposed, and a

good dimensional accuracy.

  According to another characteristic of the process according to the invention, the maximum final pressure applied to the

  mixing in the mold is of the order of LOMPA.

  The construction elements thus manufactured have a compressive strength at least equal to 1 5 MPa. According to yet another characteristic of the invention, this method consists in demolding the elements by displacement of the mold relative to the

  elements which are kept fixed in position.

  Advantageously, this process also consists in using a delayed or relatively slow setting plaster, and in mixing it uniformly and

  progressive to the aforementioned quantity of water.

  Thanks to the slow or delayed setting of this plaster, it is possible to mix without having to do it very quickly, which makes it possible to mix more

  uniformly plaster, sand and water.

  In general, the amount of filler in the aforementioned mixture can vary between 30 and 80 approximately,

in weight.

  Typically, the construction elements thus produced are planar elements for walls or interiors, for example having dimensions of the order of 25 cm × 50 cm × 10 cm, but it is of course possible by carrying out the method according to the invention of the elements construction having all

desired shapes and dimensions.

  The invention also provides a device for the exception of this process, comprising a mold with rigid and non-deformable lateral walls and with upper and lower openings closed by plates which can be moved in translation inside the mold, means for compressing the mixture. in the mold and means for demolding construction elements, this device being characterized in that the mold comprises internal partitions delimiting compartments for molding said elements and in that the demolding means comprise means for bearing on the faces elements in the mold compartments and mold translation means

parallel to said elements.

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

one 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 have no internal partitions.

  These compression means can be independent of the support means used for demolding, or else include the same means as

these support means.

  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 in

  reference to the accompanying drawings in which: - Figure 1 is a schematic view in axial section of a device according to the invention, the mold being shown open i - Figure 2 is a view corresponding to Figure 1, but shows the mold closed; - Figure 3 is a schematic top view of the mold; - Figure 4 is a view similar to Figures 1 and 2, but shows the device during

  release of construction 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 hydraulic cylinders

axially aligned.

  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 mold for manufacturing

building elements.

  This mold 14 is of generally rectangular parallelepiped shape and comprises side walls 16 which are rigid and non-deformable Its upper and lower ends 18, 20 respectively, are open and receive substantially horizontal upper 22 and lower 24 closing plates which are movable in translation vertical inside the mold 14 with little play 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 of the mold, forming stops which limit the

  races of the plates 22 and 24 inside the mold.

  The upper plate 22 can be fixed or hung on a plate 30 movable in vertical tranelation by the upper cylinder 10, and similarly the lower plate 24 is fixed or hung on a plate 32 movable 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. . 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 at a very low height, for example a about a centimeter, inside the lower part 34 of the mold, and the upper plate 22 is removed or separated from the upper opening of the mold. A mixture of plaster, of a load such as sand and water is then poured inside the mold 14, to fill the compartments 26 and cover the edges

0 superiors of partitions 28.

  This mixture comprises approximately 30 to 80% by weight of filler and approximately 70 to 20% by weight of plaster, the quantity of water being slightly greater, for example by a few percent, than that which is necessary at a maximum density. of the mixture (optimum Proctor). Depending on the grain size of the filler and the plaster, the amount of water can vary between 1.5 and 1.9 liters approximately in the case of a mixture comprising approximately 6 kilos of

sand and 4 kilos of plaster.

  It is advantageous to use a delayed or slow setting plaster to have sufficient time to mix the sand, the plaster and the water in a substantially homogeneous manner before the plaster

begins taking.

  Homogeneous mixing of plaster, sand and water is difficult, if not impossible, if you simply pour a desired amount of water onto a mixture of plaster and sand. It is necessary either to spray water on the mixture of plaster and sand when this mixture falls in the mold, or to spray water on a mixture of plaster and sand in a malaxcur 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 which cannot be molded correctly, even when compressing strongly. When an amount of the mixture corresponding to the internal volume of the mold has been poured into the mold, the mixture is slowly compressed and compressed in the mold to obtain a maximum density resulting from the evacuation of the excess water and the air contained in the mixture, which can escape through 0 the clearances between the plates 22 and 24 and the side walls of the mold, these clearances being small, of

  around a tenth of a millimeter or less.

  For this compaction and this compression, it is possible, depending on the filling conditions of the mold 14, either to move only the lower plate 24 upward until it abuts on the lower edges of the partitions 28, or to simultaneously move the plates 22 and 24 towards each other

inside the mold.

  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 travel of displacement of the plates 22 and 24 for the compaction and the compression of the mixture in the mold can be d 'about fifteen centimeters at first, the pressure applied to the mixture by the plate or plates 22, 24 being relatively low. Then on a stroke of a few centimeters, the pressure gradually increases to a value for example between 5 and lOMPa for which we arrive in the vicinity of the maximum compactness of the mixture in the mold. In general, the slow compression of the mixture is exerted during a hardness 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: - elimination of the cleavage planes which could result from the application of a unidirectional pressure, - good wetting of the entire surface of the grains of the charge, - displacement of these grains and organization of

  o their arrangement for maximum compactness.

  This latter advantage is increased when finer grains than those normally used are added to the mixture. The volume of water used in the mixture of: 5 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 can vary from a few seconds to about 15 to 20 seconds, depending on the characteristics

  particle size of the materials used.

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

internal 28.

  The elements 36 which are formed by the packed and compressed mixture are then removed from the mold.

the compartments 26 of the mold.

  For this, the upper plate 22 is raised and, as shown in FIG. 4, support means 40 are brought to the upper faces of the elements 36 to hold these elements in place when the mold 14 is moved in vertical translation upwards until the molded elements 36 are completely released from the side walls 16 and from the internal partitions 28

of the mold.

  When this is done, the support means 40 are removed and the molded elements 36 are removed from the lower plate 24. As shown diagrammatically in FIG. 4, the support means 40 are carried by vertical rods 42 connected at their upper ends.

  to support and maneuvering means 44.

  o In this embodiment, the means 40, 42, 44 for holding in place the molded elements 36 during their demolding are independent of the means

  , 22, 30 compression of the mixture in the mold.

  As a variant, these means can be combined, in particular when separate means are provided 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 can then be moved by these piston rods vertically over a distance corresponding to the end of the compression of the mixture in the mold. We can provide a cylinder for this.

hydraulic by compartment.

  In all cases, the rods 42 must have a height allowing vertical translation of the mold 14 and the internal partitions 28 sufficient to

demolding of the elements 36.

  These elements are useful in construction very soon after they are removed from the mold, 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.

  Of course, the invention is in no way limited to the embodiment described and shown and applies to the manufacture of building elements before various shapes and sizes.

Claims (6)

  1 - Process for manufacturing construction elements, in particular panels for interior walls of buildings, from a mixture of plaster, a filler 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, this process being o characterized in that it consists in slowly compressing this mixture in a mold (14) with multiple compartments (26) to pack it and to evacuate the excess water and the air contained in the mixture and reduce its volume appreciably to i5 a minimum value, then simultaneously unmold the elements (36) contained in the mold compartments and allow the setting of the plaster to take place at the outside of the mold (14).   2 - Process according to claim 1, characterized in that it consists in compressing the mixture in the mold (14) firstly with a relatively low pressure over a relatively large stroke, then with a higher pressure over a relatively small stroke. 3 Method according to claim 1 or 2, characterized in that the maximum final press ion applied to the mixture in the mold is of the order of lOMPa.   4 - Method according to one of claims   previous, characterized in that it consists in demolding the elements (36) by displacement of the mold (14) relative to the elements (36) kept stationary.   - Method according to one of claims   previous, characterized in that it consists in using a delayed or relatively slow setting plaster and mixing it in a substantially uniform manner to the above quantity of water.   lo 6 - Method according to one of claims   above, characterized in that the quantity of filler in the mixture is between 30 and 80 about by weight.   7 - Method according to one of claims   previous, characterized in that the elements (36) are panels having dimensions of the order of cmx 50cmx lOcm.   8 - Device for carrying out the process described   in one of the preceding claims, comprising   a mold (14) with rigid and non-deformable side walls (16) and with upper (18) and lower (20) openings receiving plates (22, 24) movable in translation inside the mold, means for compressing the mixture in the mold and means for demolding said construction elements (36), characterized in that the mold (14) comprises internal partitions (28) delimiting compartments for molding said elements (36) and in that the means for mold release comprise means (40) for bearing on the upper faces of the elements (36) in the mold compartments and means for translating the mold parallel to the said elements (36).   9 - Device according to claim 8, characterized in that the compression means comprise means (10, 12) for moving the upper plate (22) and / or the lower plate (24) inside parts of the mold ( 14) who are devoid of internal partitions.   - Device according to claim 9, lo characterized in that the compression means are independent of the support means (40) used for the