EP0371898A1 - Building method for a light and supple massive structure by using elementary blocks made of fragments of compressed materials - Google Patents

Abstract

The method according to the invention involves: . forming elementary blocks (3) from fragments of materials of a mass per unit volume generally lower than that of the material into which they are to be incorporated or of the structure to be produced, these fragments being compressed and stressed under load, . making a levelled bearing surface (1), . arranging the blocks (3) on the surface so as to occupy at least partially the volume of the structure to be produced and to form the body (2) of this structure, . then covering the blocks (3) with a wearing course and/or with a filler based on any suitable material.

Description

The present invention relates to the technical field of construction in the general sense, that is to say including the realization of buildings or works, as well as earthworks, roads, etc ...

In this technical field, it is frequently necessary to build massifs in order to achieve level differences, to raise a plane or to establish a load distribution base, sometimes of an insulating nature.

By way of example, it is worth mentioning level backfilling in the case of buried constructions executed from an open excavation, in the case of the construction of a parking area or a traffic lane established on sites of different levels or, again, in the case of construction of a raised load-bearing base which must have characteristics of good mechanical, sound, thermal and / or acoustic insulation with respect to a level slab of a building.

Up to now, the technique of construction of such massifs consisted in bringing back, in most cases, traditional fill materials, in earth or the like, whose density can be retained as close to 2000 kg / m³. Such a density can cause certain important problems of stresses and deformations.

In the case of backfilling a buried work, executed from an open excavation, the backfilled mass exerts, on the roof of the construction, a very significant load which obliges the builder to oversize, for this reason, the work built.

In the case of construction of parking or circulation areas on compressible land, backfill materials, having such a density, do not give great stability to the solid masses formed, due to the weak characteristics of the soil in place. Such massifs induce settlements whose evolution and magnitude over time are difficult to assess, if not by implementing expensive means of control and detection.

Such materials also induce forces and thrusts on structures in contact with or near massifs and, mainly, on structure abutments, supports, etc.

Furthermore, such a method is not practically applicable in the case of a raised load-bearing sole, since the density of these fill materials penalizes the construction of the building and does not always provide the desired insulation characteristics (for example sport, floors ...).

We therefore sought to be able to produce light and flexible massifs, so as to be able to reduce the load constraints that they generate. For this purpose, it can be considered that an acceptable proposal consists in using, for the production of a body of solid mass, materials of low density, such as, in particular, expanded polystyrene. The density of this material is, in fact, generally between 20 and 40 kg / m³, which represents a significant gain compared to traditional backfill materials.

The tests and experiments which have been carried out make it possible to envisage good reliability and acceptable longevity of such constructions which are, however, greatly penalized, because of the high cost of such a raw material, compared to traditional backfill materials.

It could be considered that the prior art offers, from a different field of application, another proposal transposable by the skilled person in the technical field concerned by the present invention.

This is the proposal to use, with backfill materials, scrap tires from vehicles, especially cars.

This technique, disclosed by the CENTRAL BRIDGE AND PAVEMENT LABORATORY (1980), consists in cutting the tread of each tire to obtain a cylindrical ring, placing the rings flat by connecting them by mutual anchors, then forming, in this way, by stacking successive layers, hollow cells connected together by the anchoring means. These cells are then filled with backfill materials which are thus immobilized and locally confined by the vertical columns formed by the superimposed treads and connected together.

In fact, such a technique is only of interest in the case of supporting structures intended to stabilize the land. The cells which are thus delimited make it possible to retain a retaining mass constituted by backfill materials which are, in general, of the same origin as the earth to be contained.

Such a technique therefore aims, mainly, the immobilization of retaining masses, but does not make it possible to reduce the density of the latter. It is therefore a technique which is not suitable for achieving the objective of the present invention which is that of making it possible to produce a light mass to reduce the stresses applied, either to the underlying layers or to the benches supporting them, either, again, to the underlying or surrounding constructions.

Mention should also be made of the teaching provided by patent FR 2 587 051 (85-13 439) constituting a development of the previous technique. According to this French patent, the realization of a flexible and light mass consists of making a volume by means of tires not filled with materials and devoid of permanent effective mutual connections, by adopting any mode of stacking or superposition, then, to do intervene one or more immobilization or anchoring layers, in particular by means of a nonwoven sheet, then cover such a solid mass with an immobilization and anchoring layer on which the load distribution layer is produced .

Such a proposal has certainly brought improvements to the previous process, but does not, however, allow to resolve all the problems which arise in all cases of obligations to carry out a light and flexible massif.

By way of example, it may be cited certain embodiments in which the permanent workload is low. The use of a lightweight block , of the type of patent FR 2 587 051 (85-13 439) is not, in all cases, the best solution, because of the low stress in vertical compression applied to the block light weight consisting of stacked or otherwise arranged tires.

It can also be cited certain embodiments in which the solid mass to be formed has only a relatively small thickness, due to the differences in levels to be filled. In these cases, the light weight is always made up of stacked tires which have a low unit cost price. On the other hand, such a massif is also always supplemented by the execution of a load distribution layer, the production of which involves a high fixed cost. The overall cost of a block is therefore proportionally higher when the thickness of the body of the block, from discarded tires, is small.

The creation of a lean mass, from discarded tires laid flat in a stack, poses, moreover, a specific problem, due to the very shape of the tires and their tangential contact. The stacking of the tires leaves, in fact, substantially vertical columns which are filled at the edge of the body of the block with filler materials making it possible to carry out a stabilization slope. The load distribution layer ordinarily covers both the light weight body and the backfill filling materials which exhibit a behavior under load different from that of tires.

In the case of massing of small volumes, such as, for example, for the abutments of works, it can then result in a heterogeneous load distribution, mainly along the edges of the mass, with consequences likely to cause, over time, disorders of the structure.

The present invention aims to propose a new process for producing a light and flexible mass representing an alternative to the previous technique, whenever it appears useful, necessary or even advantageous, to be able to strictly define a substitution volume constituting the lightened and flexible solid mass supporting directly, by itself, the load distribution layer or producing a solid mass with defined geometric contours leaving no lateral column of backfill material nested in said solid mass, or even being able to precisely regulate the prestressing to be imposed on such a light and flexible mass.

To achieve the above objectives, the invention relates to a method characterized in that it consists:
- to form elementary blocks from fragments of materials of density generally lower than that of the material in which they must be incorporated or of the work to be produced, fragments which are compressed and constrained under load,
- to establish a leveled support surface,
- to arrange the blocks on the surface to occupy, at least in part, the volume of the massif to be produced and to constitute the body of this massif,
- then to cover the blocks with a layer of use and / or filler based on any suitable material.

The invention also relates to an elementary block constituting such a block, block characterized in that it is in the form of a coherent volume made from fragments of compressed and constrained materials under load.

The present invention also has as its object, as a new industrial product, a lightweight and flexible construction block made from elementary blocks of the above type.

• La fig. 1 est une demi-coupe transversale d'un massif allégé obtenu selon le principe de l'invention mis en oeuvre dans un exemple d'application, de type remblai routier.
• Les fig. 2 et 3 sont des perspectives schématiques illustrant certains des moyens mis en oeuvre dans le procédé selon l'invention.
• Les fig. 4, 5 et 6 sont des coupes transversales illustrant différents exemples d'application de l'objet de l'invention.

Various other characteristics emerge from the description given below with reference to the accompanying drawings which show, by way of nonlimiting examples, embodiments of the subject of the invention.

• Fig. 1 is a half cross-section of a light mass obtained according to the principle of the invention used in an example of application, of the road embankment type.
• Figs. 2 and 3 are schematic perspectives illustrating some of the means used in the method according to the invention.
• Figs. 4, 5 and 6 are cross sections illustrating different examples of application of the subject of the invention.

Fig. 1 illustrates an example of application of the object of the invention in the case of the construction of a parking or circulation area raised above a ground S whose nature or composition gives it a compressible character. So as to be able to execute, on such a ground, an embankment making it possible to place the parking or circulation area at the required level, the method according to the invention consists, first of all, in producing a seat surface 1 level, which can be located in level S₁ by corresponding to the material of the site or in level S₂ by contribution of any suitable material, notably in geotechnical plan.

The method of the invention then consists in raising, on the seat surface 1 , a body 2 of light and flexible mass. The constitution of this body of block is preceded by the production of elementary blocks 3 , such as that illustrated in FIG. 2. Such an elementary block 3 is made up of fragments of materials of density generally lower than that of the material in which the block must be incorporated and, in particular, of the material of the site. By way of example, the fragments of materials are made up, more preferably, based on heterogeneous plastics waste in form and composition and coming, advantageously but not exclusively, from household waste or, by the way, by-products and / or waste industrial or, again, based on glass fibers, rock wool, etc.

An elementary block 3 is formed by compression of such waste, to form a volume, preferably but not necessarily, parallelepiped, chosen so that at least one of the dimensions is of the order of a meter. The example, illustrated in fig. 2, shows an elementary block 3 having, for example, a length l of 1 meter, a height h of 0.50 meters a width L of 0.50 meters.

The block 3 is shaped, by any appropriate means, in particular from a press, and the material fragments are compressed and constrained under load by one or more restraining means 4. Such means can be an envelope, a cover, for example in thermo-plastic shrinkable material, or, again, ligatures or straps judiciously distributed in length, width and thickness, so as to form a retaining network suitably maintaining the fragments of material. These means of restraint may or may not be final. The constraint under load, in the event of definitive means of restraint, may be significantly different from the constraint of service. On the other hand, in the event of the use of non-definitive restraint means, it is preferable, according to the invention, to subject the fragments of matter to an estimated load equal to more or less 10% of the load than the body 2 of massive will have to bear after final completion of the work.

Fig. 3 shows an elementary block 3 produced similarly to what is described above, to present, on the other hand, a height h for example equal to the fifth of the length l , the width L remaining identical to that of the previous example .

In the exemplary embodiment according to FIG. 1, the body 2 of the block is formed by juxtaposition of elementary blocks 3 which are placed side by side, contiguously, in bunk beds 5, 5₁, 5₂ ... 5 _n , by adopting a staggered device preferably. The lower bed 5 rests on the layer 1 in level S₁ or in level S₂ and constitutes a regular flat base, suitable for receiving the 5₁ bed assuming the same function for the bunk bed and so on. The body body 2 thus constituted is characterized by a great inherent stability, without it being necessary to establish it by having recourse to the interposition of anchor plies, of the woven or non woven type.

The body 2 of the massif, in the example illustrated in FIG. 1, is constituted by the superposition of different beds 5 , the proper dimension D of each gradually decreases, so as to correspond, for the bed 5 _n , to the dimension d of the structure to be produced. In this example of application, this gradual reduction is chosen so as to allow the formation of lateral slopes 6 by adding ordinary embankments mounted as the body 2 of the block is raised. The backfill materials are preferably chosen to offer the possibility of planting and revegetation.

When they exist, the embankments 6 are raised up to the upper surface of the last bed 5 _n , on which the usage slab 7 of the planned structure can be made directly. In the present case, the slab 7 is, for example, assimilated to a roadway body.

The lightened massif, produced as said above, is characterized by a low cost, due to the origin of the fragments of materials used in the constitution of the elementary blocks 3 . the massif is also characterized by a factor of flexibility which can be exactly adapted to the use or the destination of the structure, which is of particular importance for the realization of playgrounds, for example, or structures sports. The solid mass also has, due to the above characteristic, a particularly appreciable damping capacity in the preceding embodiments, as well as sound and thermal insulation capacities.

The production of elementary blocks 3 , from fragments of discarded plastics, also has the advantage of reducing, or even eliminating the existence of waste. domestic or industrial which, for the moment, still pose problems of treatment, recycling or destruction.

In addition to the above characteristics, it should be noted that the construction of the massif can be carried out quickly, without involving particularly long and delicate processes, since it is only a question of laying elementary blocks 3 which have , by their shape, their own stability on any of their faces. In the case of application according to fig. 1, the elementary blocks 3 are placed flat on one of the large side faces. It could be considered placing them on edge or, on the contrary, standing.

Another advantage of the subject of the invention lies in the absence of any particular treatment of the layer 1, at the level S₁ or S₂, since it suffices to carry out a leveling to allow the laying of the lower bed 5.

An advantage of the same order resides in the absence of need to interpose anchoring layers, textile or not, and in the absence of need to cover the solid mass with a load distribution layer on which the slab of usage, for example, must be asked.

The realization of a lean mass, under the road body of the type of fig. 1, can be easily obtained from elementary blocks 3 formed by compression of polyethylene film waste to adopt a parallelepiped shape of 1 meter in length, 0.50 meters in height and 0.50 meters or 1 meter in width. Each block is, for example, produced by compression and stress under load of 20 kPa, with restraint of the waste or fragments by means of ligatures of definitive nature or not. Such a block has a density of 3.5 kN / m³ and makes it possible to constitute a solid mass six times lighter than that which, in the same case of application, would be made from embankments usually used.

The compression and stress under load imposed on each block give it a vertical deformation modulus, a horizontal Poisson 's ratio and a thrust coefficient of particularly remarkable values.

Fig. 4 illustrates another example of application in which it is advisable to produce a lightened substitution mass below a civil engineering structure 8. In such a case, an excavation or pit 9 is made , the dimensions of which are determined in relation multiple with those of blocks 3 , so as to allow an exact filling in the three dimensions. Such an embodiment allows the execution of vertical front walls extending beyond the footprint of the structure 8 so that the load of the latter is fully supported by the various beds 5 of blocks 3 .

In such an embodiment, the blocks 3 can be formed in the form of cubic volumes of 1 m³, from waste polyethylene films, compressed and constrained under a load of 50 kPa. The means of restraint used is made up of ligatures, which may not be definitive over time.

The body 2 of the bed is made up to a level lower than that of the surface S of the ground to be covered with a sandy layer 10 on which the work 8 rests .

The density of the blocks 3 , close to 6 kN / m³, makes it possible to produce a light mass which does not increase the stress on the ground and capable of supporting, in a stable manner, the structure 8.

In an example of a similar application, it is possible to produce the elementary blocks 3 from mixtures of fragments of polyethylene films and of polystyrene waste, so as to obtain elementary blocks having a density of approximately 2.5 kN / m³.

Fig. 5 shows that a lightweight block, of the above type, can be produced in a similar way in the application to a roadway body 11 whose lateral edges are delimited by retaining walls 12. The block makes it possible to achieve lightening under road and reduce the thrust imposed on the lateral retaining walls 12.

It must be considered that a body of mass can be carried out in a similar way above the vault of a buried work to fill the excavated excavation and to cause a discharge vault according to the so-called "Marston Spangler" effect.

Fig. 6 illustrates an example of application in which it is advisable to produce a solid, with a draining and flexible character, as is, for example, the case of playgrounds and sports grounds. In such a case, the body 2 of the block consists, for example, by the establishment of a bed 5 of blocks 3 which are placed at a relative distance from each other, so as to delimit intervals 13. The block 2 is supplemented by a filling material 14, for example in sandy sand, ensuring the immobilization and the maintenance of the different blocks. A use layer 15 is then distributed over the material 14, such a layer being, for example, made entirely or partially of topsoil.

Although this is not absolutely necessary, it is possible to have, on the surface S of the ground and before the installation of the blocks 3 , a geotextile sheet 16, such as in BIDIM U 44.

In such an application example, it is also possible to provide, between at least some of the blocks 3 , devices 17 assuming a function of drainage and collection of infiltration water with the additional possibility of playing the role of a network. sub-irrigation or a heating function, in particular by circulation of a heat-transfer fluid.

The massif is characterized by a flexible character, particularly adapted to the physiological requirements or aptitudes of the human body, depending on the practice of a specific sport.

Blocks 3 , in the application according to FIG. 6, can be made from waste or fragments of plastics, such as polyethylene and polystyrene, in the form of volumes of 1 meter in length, 1 meter in width and 0.20 meters in height. Plastic waste is compressed and constrained under a load of 20 kPa, so as to have a density of 2.5 kN / m³. The constitution of blocks 3 is preferably made with restraint means of a definitive nature. Among the particularly interesting applications, it is worth mentioning the tennis courts, the running and jumping areas, in particular with the pole, in height, in length, the riding grounds, the rackets of reception of ski jump springboard , etc ...

The invention is not limited to the examples described and shown, since various modifications can be made thereto without going beyond its scope.

Claims (13)

1 - Process for producing a light and flexible massif, consisting of:
- to form elementary blocks from fragments of matter,
- to establish a leveled support surface,
- to arrange the blocks on the surface to occupy, at least in part, the volume of the massif to be produced and to constitute the body of this massif,
- then cover the blocks with a layer of use and / or filler based on any suitable material,
characterized in that the elementary blocks are made from fragments of material with a density lower than that of the material in which they are to be incorporated or of the work to be produced, said fragments being compressed and constrained under load. 2 - Process according to claim 1, characterized in that it consists in producing the elementary blocks from fragments of plastic materials, heterogeneous in shape and composition. 3 - Method according to claim 1 or 2, characterized in that it consists in forcing the fragments under load by means of restraint of definitive nature. 4 - Method according to one of claims 1 and 2, characterized in that it consists in compressing the fragments and in forcing them under a load equal to more or less 10% of the load to be supported when the means of restraint has a not final. 5 - Method according to claim 1, characterized in that it consists in placing the elementary blocks at a distance from each other and in filling the intervals separating them by providing a filling material. 6 - elementary block of constitution of a light and flexible massif for the implementation of the method according to claim 1, being in the form of a coherent volume (3) consisting from fragments of compressed and stressed materials under load, characterized in that the elementary blocks consist of fragments of materials with a density lower than that of the material in which they are to be incorporated or of the structure to be produced. 7 - Elementary block according to claim 6, characterized in that it is made from plastic fragments, heterogeneous in shape and composition. 8 - Elementary block according to claim 6 or 7, characterized in that the fragments are compressed and forced under load by a peripheral restraining means ( 4 ). 9 - Elementary block according to claim 8, characterized in that the restraining means is constituted by ligatures. 10 - Elementary block according to claim 8, characterized in that the compression means is constituted by a cover. 11 - Elementary block according to one of claims 6 to 8, characterized in that the fragments are compressed and constrained under a load equal to more or less 10% of the load that the block must support when the means of restraint has a character not final. 12 - Elementary block according to one of claims 6 to 11, characterized in that it has at least one dimension of the order of one meter. 13 - Lightweight and flexible construction mass made from elementary blocks according to one of claims 6 to 12.

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