EP3910129A1 - Method for producing a three-dimensional single-piece concrete structure or part thereof and three-dimensional concrete structure or part thereof thus obtained - Google Patents

Abstract

This method uses a closed mold composed of a lower mold (2) and an upper mold or cover (3, 4) defining between them a volume intended to be filled with concrete, consisting of: ▪ installing the mold lower (2) intended, ultimately, to define said at least one horizontal flat surface: ▪ to position the upper mold or cover (3, 4) facing said lower mold (2), and to fix it on said lower mold; ▪ to be injected into the volume defined by the two lower and upper molds respectively, and from the lower base of said volume, self-placing concrete, until the entire said volume is filled; ▪ after the concrete has solidified, in removing the upper mold and the lower mold, and therefore in unmolding the structure or part of a three-dimensional structure in concrete; then in turning over the structure or part of the structure thus obtained, in order to have the at least one horizontal flat surface in operational position , i.e. in the upper position when said structure is erected in place on site.

Description

FIELD OF THE INVENTION

The invention relates first of all to a method for the production, in particular in a factory, of structures or parts of three-dimensional monobloc concrete structures, and more particularly, although in a non-limiting manner, of staircases or parts of monobloc staircases. concrete.

The invention also relates to the structures or parts of three-dimensional one-piece concrete structures thus obtained and, more specifically, to one-piece concrete stairs or parts of stairs.

PRIOR STATE OF THE ART

Traditionally, concrete stairs, in particular of the monobloc type, are produced on site. However, more and more, these stairs are made in the factory, then transported and erected on site.

Thus, in the context of the production of such concrete stairs directly on site, they are produced as follows, for example in the case where the staircase has a central shaft.

First of all, a mold is placed, defining a central column intended to constitute the barrel. The latter is produced by pouring concrete through the upper end of the mold defining such a central shaft. Then the concrete is poured on the areas of the mold intended to define the steps and risers. The concrete thus deposited is vibrated, then the operator smooths the steps thus made, in particular using a shovel or a trowel, then smooths the concrete not yet solidified with a smoothing machine.

Indeed, conventionally, it is created concomitantly with the pouring of the concrete, air bubbles, which rise to the surface when the concrete solidifies. These air bubbles can congeal in the mass of the concrete or on the walls of the formwork, but can also burst on the upper surface of each of the steps, causing craters to appear, which should be eliminated. This bubbling phenomenon, well known in the field in question, generates the need to carry out a second smoothing operation when the concrete has started to set.

What is more, it is not uncommon, notwithstanding this double smoothing operation, for a deposit of another coating or plaster to be applied to the facing of concrete parts, for aesthetic reasons in particular, in order to completely conceal this bubbling phenomenon, but also in order to make up for any flatness defects.

From now on, it will easily be understood that the production of monobloc concrete stairs, as described above, whether these stairs are produced on site or in the factory, involves significant finishing work, which is particularly time-consuming.

Moreover, although certain techniques, such as the vibration of concrete, have been developed in order to reduce this problem, the product nevertheless comes out bubbled and then requires a significant finishing work to mask these bubbles.

In addition, the finish must be strong enough to allow repeated passages of users without showing any wear or bursting related to the presence of air bubbles. This explains the need sometimes for two coats of plaster, further increasing the loss of time.

In addition, the realization of such stairs is accompanied by a great difficulty for the operator (s), insofar as the latter must proceed, in addition to the pouring of the concrete, to its equalization at the level of each of the steps in particular at the using a shovel, it being emphasized that this operation must be carried out even though the concrete is not solidified. In addition to this aspect of arduousness, there is also a safety problem, precisely because of the positioning of the operator as best he can, to ensure this operation of equalizing the steps and then smoothing the concrete, the operator having to work in the staircase in progress, the risk of falling from a certain height remaining present.

Finally, due to the implementation of a relatively firm concrete, it is traditionally appropriate to carry out an operation of vibration of the mold or internal with vibrating needles, adding to the aforementioned drawbacks a noise nuisance, additionally affecting the conditions of operator's job.

• ▪ à fixer et installer le moule inférieur en position opérationnelle ;
• ▪ à positionner le moule supérieur ou capot en regard dudit moule inférieur et à le fixer sur ledit moule inférieur ;
• ▪ à injecter dans le volume défini par les deux moules respectivement inférieur et supérieur, et à partir de la base inférieure dudit volume, du béton notamment de type auto-plaçant, jusqu'à combler l'intégralité dudit volume ;
• ▪ puis, après prise en masse du béton, à ôter le moule supérieur et le moule inférieur, et donc à démouler l'escalier ainsi réalisé.

In order to overcome these difficulties, the Applicant has proposed, for example in document FR 3,081,896 , a method for producing such monobloc concrete stairs, using a closed mold composed of a lower mold and an upper mold or cover, defining between them a volume intended to be filled with concrete, said method consisting of :

• ▪ to fix and install the lower mold in operational position;
• ▪ positioning the upper mold or cover facing said lower mold and fixing it on said lower mold;
• ▪ injecting concrete, in particular of the self-placing type, into the volume defined by the two lower and upper molds, respectively, and from the lower base of said volume, until all of said volume is filled;
• ▪ then, after the concrete has solidified, removing the upper mold and the lower mold, and therefore unmolding the staircase thus produced.

In doing so, by virtue of the method thus described, the presence of air bubbles is reduced, in particular at the level of the walking platforms, this reduction of air bubbles being able to be optimized, still according to the teachings of this document, by the implementation. work at the level of the internal face of the upper mold or cover, that is to say of the face opposite the tread plate, of a mortar, prior to the injection of the self-compacting concrete, said mortar having mainly intended to trap the air resulting from the solidification of the concrete between said concrete and the mortar.

• ▪ une étape supplémentaire dans le cadre de la réalisation d'un tel escalier,
• ▪ un surenchérissement du prix de revient d'un tel escalier,
• ▪ mais également la difficulté à caler concomitamment l'adhérence du mortier contre la face inférieure, en l'espèce huilée du capot supérieur, et sa prise en masse.

While undoubtedly the method thus described makes it possible to significantly improve the techniques known from the prior art, and in particular to have the possibility of climbing a staircase directly on site, it nevertheless has a certain number of drawbacks. Among these, in particular the step of spraying the mortar on the underside of the upper mold or cover, which in fact generates:

• ▪ an additional step in the construction of such a staircase,
• ▪ an increase in the cost price of such a staircase,
• ▪ but also the difficulty in simultaneously wedging the adhesion of the mortar against the underside, in this case the oiled upper cover, and its solidification.

To sum up, if the process thus described in the prior art makes it possible to reduce the phenomenon of bubbling concrete, experience shows, first of all, that we are not completely free from said phenomenon, since indeed, the air bubbles are frequently found enclosed substantially in the vicinity of the upper horizontal faces, that is to say, at the level of the tread plates.

In addition, and as already said, the use of a mortar to reduce this bubbling phenomenon ultimately turns out to be relatively complex to control.

The object of the invention is to overcome these drawbacks.

SUMMARY OF THE INVENTION

If the method described in the previously mentioned prior art advantageously allows the production of a staircase on site, therefore directly without requiring transport of said staircase or parts of such a staircase, the present invention is more oriented towards the production of structures. three-dimensional concrete monoblocks produced in the factory, certainly then requiring the displacement of said structure or part of a structure on the site with a view to its final assembly or its final assembly or erection.

The method according to the invention for producing a structure or part of a three-dimensional monobloc structure in concrete, provided with at least one horizontal flat surface, basically consists in producing said structure "upside down", that is, that is to say, to reverse the erection of the mold with respect to the method described in the document FR 3081 896 . This method therefore also implements a closed mold composed of a lower mold and an upper mold or cover defining between them a volume intended to be filled with concrete.

• ▪ à installer le moule inférieur destiné, in fine, à définir ladite au moins une surface plane horizontale, ledit moule inférieur présentant une succession de parties verticales et horizontales, lesdites parties horizontales étant destinées à définir ladite au moins une surface plane ;
• ▪ à positionner le moule supérieur ou capot en regard dudit moule inférieur, et à le fixer sur ledit moule inférieur ;
• ▪ à injecter dans le volume défini par les deux moules respectivement inférieur et supérieur, et à partir de la base inférieure dudit volume, du béton auto-plaçant, jusqu'à combler l'intégralité dudit volume ;
• ▪ après prise en masse du béton, à ôter le moule supérieur et le moule inférieur, et donc à démouler la structure ou partie de structure tridimensionnelle en béton ;
• ▪ puis à retourner la structure ou partie de structure ainsi obtenue, afin de disposer de la au moins une surface plane horizontale en position opérationnelle, c'est-à-dire en position supérieure lorsque ladite structure est érigée en place sur site.

This process consists of:

• ▪ to install the lower mold intended, ultimately, to define said at least one horizontal flat surface, said lower mold having a succession of vertical and horizontal parts, said horizontal parts being intended to define said at least one flat surface;
• ▪ positioning the upper mold or cover facing said lower mold, and fixing it to said lower mold;
• ▪ injecting into the volume defined by the two lower and upper molds respectively, and from the lower base of said volume, self-placing concrete, until all of said volume is filled;
• ▪ after the concrete has solidified, removing the upper mold and the lower mold, and therefore unmolding the structure or part of a three-dimensional structure in concrete;
• ▪ then turning over the structure or part of the structure thus obtained, in order to have the at least one horizontal flat surface in the operational position, that is to say in the upper position when said structure is erected in place on site.

In other words, contrary to the teachings of the patent FR 3,081,896 , the structure, and typically the staircase, is made upside down, without the use of any mortar, since also, as mentioned in the description of the prior art, the air bubbles resulting from the pouring concrete are found enclosed at the level of the upper face of the mold, therefore in this case, due to the realization of said structure and in particular of the staircase upside down, at the level of the lower face of said staircase once this one erected. This avoids observing defects at the level of the functional surface of the staircase, that is to say of the tread plate and, moreover, due to the injection of concrete through the lowest point of the staircase. volume defined by the mold, said air bubbles, where appropriate formed, tend to form at the upper level of said mold and therefore, once again, at the level of the non-functional lower face of the three-dimensional structure, in particular of the staircase .

According to an advantageous characteristic of the invention, a vent is positioned at the highest point of the volume defined by the two molds, respectively lower and upper. In doing so, the injected concrete not only fills the entirety of said volume, but also overflows from said volume in its upper part, that is to say higher than the three-dimensional structure to be produced. This ensures complete filling of the mold. The Concrete core resulting from this overflow, and obviously unnecessary, is broken after the concrete sets solid during demolding.

According to an advantageous characteristic of the invention and, here again, with the aim of avoiding the formation of air bubbles during the solidification of the concrete, once the mold has been produced, that is to say after installation of the lower mold and the upper mold, the assembly is inclined, typically at an angle of between 3 and 25 degrees relative to the horizontal, during the operation of pouring the concrete. Because of this low inclination of the mold thus formed during the concrete pouring operation, air bubbles which naturally tend to be trapped at the horizontal faces, have not de facto more horizontal faces come to be imprisoned, and are liable to escape at the level of the creepage line arising from the inclination of said mold.

In the same spirit, according to another variant of the invention, at least part of the surfaces of said mold intended to define the non-vertical faces of the structure is provided with a draft, again typically inclined from 3 to 25 degrees relative to the structure. horizontally, thus making it possible to avoid any horizontal face when pouring concrete, thus promoting the evacuation of any air bubbles formed. In doing so, once the structure, and in particular the staircase has been completed, then turned over, and erected, the lower face no longer has a rack-and-pinion section with parallel faces as frequently observed, but a lower face having a plane inclined with respect to the 'horizontal.

According to yet another variant of the invention, and here again always with the objective of avoiding the formation of bubbling during the solidification of the concrete, the upper face of the mold is no longer in the form of a rack, as in the previous case, but has a continuous curvature, which will become the underside of the staircase, this continuous curvature thus avoiding any horizontal faces liable to allow the imprisonment of air bubbles.

The invention also relates to three-dimensional monoblock structures and concrete monobloc stairs obtained by implementing this method.

DESCRIPTION OF FIGURES

• La figure 1 est une représentation schématique en perspective d'un moule inférieur conforme à l'invention en vue de la réalisation d'un escalier monobloc en béton à fût central.
• La figure 2 est une vue schématique latérale du moule inférieur de la figure 1.
• La figure 3 est une vue schématique en perspective, selon deux orientations différentes de la partie inférieure du moule supérieur conforme à l'invention, et apte à coopérer avec le moule inférieur des figures 1 et 2.
• La figure 4 est une vue analogue à la figure 3, mais de la partie supérieure dudit moule supérieur.
• La figure 5 est une vue schématique en éclaté illustrant les différentes parties du moule, outre l'escalier en béton résultant de la mise en œuvre du procédé de l'invention.
• La figure 6 est une vue schématique illustrant un escalier résultant du procédé de l'invention, représenté à l'envers, et présentant au niveau de sa sous-face des zones inclinées, résultant de dépouilles ménagées au sein du moule.
• La figure 7 est une vue schématique en perspective d'un escalier représenté à l'envers ou retourné, mettant en évidence une autre variante de l'invention, en l'espèce un escalier à surface inférieure lisse et à courbure continue avec fût central.
• La figure 8 est une vue analogue à la figure 7, mais d'un escalier sans fût central.

The manner in which the invention can be implemented and the advantages which result therefrom will emerge more clearly from the exemplary embodiments which follow, given by way of indication and without limitation, in support of the appended figures.

• The figure 1 is a schematic perspective representation of a lower mold according to the invention with a view to producing a one-piece concrete staircase with a central shaft.
• The figure 2 is a schematic side view of the lower mold of the figure 1 .
• The figure 3 is a schematic perspective view, in two different orientations of the lower part of the upper mold according to the invention, and capable of cooperating with the lower mold of the figures 1 and 2 .
• The figure 4 is a view analogous to figure 3 , but from the upper part of said upper mold.
• The figure 5 is a schematic exploded view illustrating the different parts of the mold, in addition to the concrete staircase resulting from the implementation of the method of the invention.
• The figure 6 is a schematic view illustrating a staircase resulting from the process of the invention, shown upside down, and having inclined areas at its underside, resulting from undercuts made within the mold.
• The figure 7 is a schematic perspective view of a staircase shown upside down or turned upside down, showing another variant of the invention, in this case a staircase with a smooth lower surface and continuous curvature with a central shaft.
• The figure 8 is a view analogous to figure 7 , but of a staircase without central shaft.

DETAILED DESCRIPTION OF THE INVENTION

The following description is made in relation to the manufacture of a one-piece concrete staircase.

It must however be kept in mind that the invention is aimed at the production of any three-dimensional concrete structure, and that only the shape of the molds is liable to vary in order to produce said structure, the general principle described below remaining strictly identical. According to the method of the invention, in order to produce such a one-piece concrete staircase (1), more particularly in the factory and not on site, two molds are used, respectively a lower mold (2) shown in the drawings. figures 1 and 2 , and an upper mold, in this case consisting of a lower cover (3) and an upper cover (4) shown within the figures 3 and 4 . As can be seen in these figures, the molds are erected vertically.

With regard to the lower mold (2) shown in said figures 1 and 2 , the latter has a succession of vertical (5) and horizontal (6) parts, said horizontal parts (6) being intended to define the tread plates (7) of the staircase (1) resulting from the method of the invention , being recalled that according to said process, the staircase is molded in an inverted or inverted position, as can be observed in particular on the figures 7 and 8 . Typically, this mold is made of steel and corresponds to the entire flight of stairs that one wishes to produce.

As a corollary, the figures 3 and 4 respectively illustrate the lower part or lower cover (3) of the upper mold and the upper part or upper cover (4) of the upper mold, intended, once in place and fixed on the lower mold (2) described in relation to the figures 1 and 2 , to define a volume, into which a self-compacting concrete will be injected.

In this embodiment, said lower (3) and upper (4) covers also consist of a succession of horizontal (8) and vertical (9) parts, so that the lower face, also called underside (13 ) of the staircase resulting from the method of the invention is in the form of a rack, like the one shown in figure 5 . It should in fact be recalled that, due to the realization of the staircase in an inverted position, this upper mold will define, in fact, the lower face of the staircase. In the specific case, this lower part therefore has a rack.

However, and as described for example in relation to figures 7 and 8 , this lower surface (13) of the staircase could be smooth and continuous, so that the shape of the upper cover would be adapted accordingly.

We have shown in relation to the figure 5 an exploded view tending to illustrate the assembly of the various parts of the mold and their cooperation with the staircase following its realization. These different parts of the mold are assembled together, in particular by screwing, in order to promote the subsequent demolding of the staircase, once the concrete has solidified.

This assembly defines a closed volume, into which the self-compacting concrete is injected. According to an essential characteristic of the invention, this injection is carried out at the level of the base of said volume. We have thus materialized on the figures 3 and 5 , the injection point (10) of the concrete within this volume, said injection point in this case being made within the lower vertical part (9) of the upper mold.

This concrete, with a much more liquid consistency than the traditional concretes used for stairs, is therefore injected from the lower end of the mold in an upward movement, in particular by means of a suitable pump, and more particularly of a peristaltic pump. Self-compacting concrete therefore does not need to be vibrated, an operation usually very physical and painful, and has a greatly reduced number of air bubbles, making it possible to obtain a finished product that is smoother on the surface.

This pumping takes place until the volume defined by the molds, respectively lower and upper, is completely filled.

According to an advantageous characteristic of the invention, the upper end (11) of the mold is provided with a vent (12), allowing the air to escape as the volume defined by the assembly of said molds together, and de facto favoring the elimination of air bubbles proper, one of the essential pitfalls that the present invention aims to avoid.

More precisely, as the self-placing concrete is injected at the level of the lower injection zone (10), the concrete progresses inside said volume towards the top of the mold, inducing full filling of the volume defined by the mold, until the concrete reaches the top of said volume and escapes at the level of the vent (12). When the concrete actually reaches the vent, the injection of concrete ceases.

Once the concrete has set in mass, the duration of solidification depending on the nature of the concrete, that is to say once the stairs can be removed from the mold and therefore the various elements of the molds illustrated in relation to be removed. with the figures 1 to 4 , this results in the presence of an upper core corresponding to the vent, which can be broken at this time.

According to an advantageous embodiment, and illustrated in relation to the figure 6 , in which there is shown a staircase (1) provided with a central shaft (14) in the inverted position, the mold is provided with undercuts, typically inclined from 3 to 25 degrees relative to the horizontal. The implementation of such undercuts, resulting in inclined sides (15) at the level of the underside (13) of the staircase, aims to optimize the objective sought by the present invention, namely to avoid the formation of air bubbles that can get trapped. Indeed, the presence of these spoils tends, due to the mode of injection of the concrete from the lower base of the volume defined by the two molds, to drive out the concrete as and when at each of the steps in direction of the upper step and, consequently, to expel air bubbles.

Alternatively, or even cumulatively, it is also possible according to the invention to slightly incline the entire mold during the concrete injection operation, again typically by a value of between 3 and 25 degrees relative to the horizontal, always with the same objective of expelling air bubbles. Whatever the embodiment of the invention, the primary objective is to avoid the formation of air bubbles between the upper mold and the concrete.

Alternatively, and as mentioned above, it is conceivable to eliminate any discontinuity at the level of the casing of the upper mold. In other words, said upper mold is given a smooth and continuous shape, making it possible to produce a staircase as illustrated in the figures. figures 7 and 8 , respectively with and without central shaft. It is observed that the lower face of the staircase, since it is also represented in the inverted or inverted position, no longer has a rack, but a continuous surface. Because of this continuity of the upper mold, there is therefore no longer any horizontal or substantially horizontal surface capable of allowing the trapping of air bubbles.

Advantageously, whatever the embodiment chosen, robust self-compacting concrete is used while avoiding saturation in the dosage of admixtures in order to avoid the risk of microsegregation or foaming on the surface, liable to be caused by plasticizers or superplasticizers type deflocculants. Typically, this self-compacting concrete belongs to class SF2 (spreading between 660mm and 750mm), or to class SF3 (spreading between 760mm and 850mm), these two classes being defined by standard NF EN 206, the spread being a test described by standard NF EN 12350-8.

The method of the invention results in the possibility of producing a three-dimensional concrete structure, and in particular a one-piece concrete staircase, making it possible to dispense with air bubbles at the level of the tread plates, that is to say of the truly functional area of the staircase, without requiring prior treatment of the molds, except for oiling the internal face of the molds in order to promote demolding (this demolding oil may consist of a solvent (for example sold under the reference Grâce wax E-31), a synthetic oil (for example marketed under the reference Chryso Dem Oléo 64), a vegetable or vegetable-based oil (for example marketed under the reference Grâce Décobio S33)) or the implementation of any additional mortar, thus making it possible to facilitate the production process and to reduce its manufacturing costs.

Claims (7)

Method for producing a three-dimensional monoblock structure or part of a concrete structure, provided with at least one horizontal flat surface (7), said method using a closed mold composed of a lower mold (2) and an upper mold (3, 4) or cover defining between them a volume intended to be filled with concrete, consisting of: ▪ to install the lower mold (2) intended, ultimately, to define said at least one horizontal flat surface, said lower mold (2) having a succession of vertical (5) and horizontal (6) parts, said horizontal parts (6) ) being intended to define said at least one planar surface (7); ▪ positioning the upper mold (3, 4) or cover facing said lower mold, and fixing it on said lower mold (2); ▪ injecting into the volume defined by the two lower and upper molds respectively, and from the lower base of said volume, self-placing concrete, until all of said volume is filled; ▪ after the concrete has solidified, removing the upper mold (3, 4) and the lower mold (2), and therefore unmolding the structure or part of a three-dimensional structure in concrete; ▪ then turning over the structure or part of the structure thus obtained, in order to have the at least one horizontal flat surface in the operational position, that is to say in the upper position when said structure is erected in place on site. A method for producing a structure or a part of a three-dimensional monobloc concrete structure according to claim 1, in which a vent (12) at the most point is furthermore positioned on one or the other of the two molds. top of the volume defined by said molds (2, 3, 4), so as to allow the self-compacting concrete injected from the lower base of said volume to fill all of said volume, then to overflow from said volume in its upper part, that is to say higher than the three-dimensional structure to be produced. Process for producing a structure or part of a three-dimensional one-piece concrete structure according to one of claims 1 and 2, in which, once the mold has been produced, that is to say after installation of the lower mold and the upper mold, the assembly is inclined at an angle of between 3 and 25 degrees relative to the horizontal during the concrete pouring operation. Method for producing a structure or part of a three-dimensional monobloc concrete structure according to one of claims 1 to 3, in which the mold has a sagittal section in the form of a rack, suitable for defining at the level of the structure three-dimensional to produce vertical faces and non-vertical faces, at least part of the surfaces of said mold intended to define the non-vertical faces being provided with a draft. A method for producing a three-dimensional one-piece concrete structure or part of a structure according to claim 4, wherein the undercuts are inclined 3 to 25 degrees from the horizontal. Method for producing a structure or part of a three-dimensional monobloc structure in concrete according to one of claims 1 to 3, in which the upper face of the upper mold or cover has a continuous curvature. Staircase or part of a concrete monobloc staircase having a series of counter steps and tread plates obtained by the process according to one of claims 1 to 6.

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