Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
  • E02D3/005—Soil-conditioning by mixing with fibrous materials, filaments, open mesh or the like
• • E—FIXED CONSTRUCTIONS
  • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
  • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
  • E01C3/00—Foundations for pavings
  • E01C3/003—Foundations for pavings characterised by material or composition used, e.g. waste or recycled material

Definitions

• the invention relates to soil preparation techniques in which sands or granular substitute materials are used, it relates in particular to the production of underlays for paths, roads or sports grounds.
• the second phase consists in depositing on the ground thus prepared a layer of form whose first function will be to allow the displacement of the convoys and machines on the ground by avoiding degrading it or clogging the machines.
• one or more other layers of a different nature are then deposited, said foundation layer, base layer, etc., the common role of which is to support the more superficial layers bound by large quantities of hydraulic or bituminous binders.
• Each of the underlying layers is made with well-defined quality sand which unfortunately is generally not available in the vicinity of the site. Although the price of such a material is not high its transport can be very expensive.
• One of the aims of the invention is to make it possible to use, for the production of the underlying layers, materials in particular sand from quarries neighboring the site to which fibers are added which give them the desired properties.
• Another object of the invention is to improve the participation of the underlying layers in the stability of the road and in the resistance of the roadway over time.
• the invention must allow the repair of degraded roads with the reuse of aggregates already in place or the addition of new powders or aggregates.
• the invention also aims to provide a product for strengthening which is compatible with the usual additions of sands such as hydraulic binders.
• Synthetic fibers have a length of 15 to 100 mm and their diameter is between 30 and 100 ⁇ m. Fibers made of various materials are cited, the examples relate to polyacrylonitrile fibers.
• the invention thanks to the choice of a suitable material and the use of new methods for the incorporation of fiber in mineral granules provides a better quality product, easier to process and, after all, cheaper.
• patent application FR-A-2 368 211 proposes to add a cable of 27,000 or 100,000 curly filaments made of polyvinyl chloride, acrylonitrile or viscose in sand to stabilize dunes and to seed them .
• the main aim here is to stabilize slopes and limit wind erosion.
• the invention was developed for a different purpose, stabilizing the floors intended to withstand localized forces such as those due to trampling or rolling of machines, during the installation of the upper layers and thereafter, ensuring stable support for the developed land or road, the means offered are also different.
• the invention provides a granular or pulverulent material intended for the production of soils, layers or sub-layers of land or pavement and comprising a mixture based on mineral or organic powders or granules and fibers, in which the fibers are filaments in the form of bundles with a length of less than 100 mm, especially mineral fibers, in particular glass fibers with bundles made up of at least 40 filaments each with a unit diameter between 5 and 25 ⁇ m.
• the beams have a length of between 20 and 50 mm.
• the proportion by weight of the filament bundles in the mixture is between 0.01% and 0.5% and preferably between 0.01 and 0.1%. They are preferably cut from textile glass threads, the filaments of which have a diameter of between 10 and 16 ⁇ m, such as 11 or 14 ⁇ m.
• the powder to which the glass filaments are added advantageously mainly comprises industrial by-products such as fly ash or slag while the granules are sand to which a variable amount of hydraulic binder can be added.
• the invention also provides that the granules are grave treated with hydraulic binders.
• the glass filaments are based on an alkali-resistant composition.
• the granular material according to the invention allows the production of soils, layers or sub-layers of land or roads which have, compared to pulverulent materials loaded with known fibers, the advantage of at least equivalent performance despite small quantities of fibers. .
• the invention also relates to a process for preparing a mixture of mineral granules and glass fibers intended to constitute a form layer for roadways, it comprises the following stages which are linked in succession or are carried out simultaneously:
• the method of the invention provides that the bundles of filaments are deposited directly on the leveled ground consisting of mineral or organic powders or granules and that the mixing of the bundles of filaments with the powders or granules is carried out by the passage of a construction machine of the strawberry type, the distribution being advantageously carried out by a construction machine of the seeder type.
• the method also provides for the bundles to be cut from strand (s) of wire, immediately before being deposited on the leveled ground.
• Another variant of the method provides that to restore a layer of pavement in gravel treated with hydraulic binders, the following steps are observed:
• the methods of the invention have the advantage of avoiding any segregation or dispersion of the fibers elsewhere than in the granules. This limits pollution and losses. Furthermore, they make it possible to obtain a much more regular distribution of the fibers which makes it possible to control the proportion thereof.
• the invention also provides a fixed device for the preparation of a mixture of powders or granules and textile glass fibers intended to constitute grounds, layers or under-layers of grounds or pavements which comprises in particular a machine of continuous yarn cutter arranged in the vicinity of a conveyor, a cut yarn distribution system on the conveyor which in particular transports powders or granules as well as, possibly downstream from the cut yarn distributor, a powder or granule distributor covering the cut wires.
• This device allows in particular the simple implementation of the method of the invention in the immediate vicinity of the mobile site for the production of sports grounds or the construction of roadways. Another device, mobile that one, is also proposed.
• FIG. 1 represents the device allowing the implementation of the process of the invention within the framework of a centralized preparation of the granulated material.
• Figures 2 and 3 show results of comparative sand cracking tests with hydraulic binders respectively: times for the first cracking of shrinkage (Figure 2) and crack width after 28 days (Figure 3).
• FIG. 1 illustrates a first centralized method for producing the mixture between the granular or pulverulent material and the fibers.
• hoppers 1, 2 containing the pulverulent or granulated materials to be used, for example on the one hand an all-purpose sand from a quarry close to the site and a corrective sand, that which, added in large quantities, is - in the absence of fibers necessary to provide the mixture with the desired lift.
• a conveyor belt 3 below the hoppers, and leading from one to the other, a conveyor belt 3 has been installed.
• the hopper 1 deposits a certain thickness of the material, such as all-purpose sand, on the conveyor.
• This sand then passes into 4 under a machine 5 for cutting the glass strands. This is supplied with strands of wire 6 from several coils such as 7 unwound from the inside.
• the machine 5 generally comprises several rollers 8, at least one of which is fitted with knives 9 which cut the set of wicks 6 into sections of defined length 10.
• Each wick has a very large number of threads, in general more than 400, 1200 per example.
• the nature of the glass constituting the fibers is not decisive for the lift. It is only in special cases, such as conditions of attack by binders, that it should be substituted for the usual E glass, a glass of a different composition.
• European patent EP-B-0040145 proposes for example a machine intended to cut wires into sections of a predetermined length and which comprises a rotary drum whose surface is smooth and a second drum equipped with blades arranged perpendicularly to its periphery, the blades being fixed by their only ends and their bases opposite to their cutting edge remaining entirely free while members ensure the compression of the wire.
• the filament bundles 10 are preferably deposited over the entire width of the sand transported by the strip 3. After the fibers have been deposited, the materials pass under the hopper 2 where an amount of sand, for example a corrective sand from a distant quarry (but then, thanks to the stabilizing effect of fibers in minimum quantity) is deposited. This avoids immediately covering the fibers that the dispersion is disturbed. At the exit of the conveyor belt 3, the materials fall into a mixer, not shown, where a homogenization of the distribution of the fibers in the sand
• the technique involves three stages, soil preparation, beam distribution and mixing.
• the preparation consists in leveling the ground and depositing the granular materials from outside there or if by its nature, itself agrees, to loosen it on the depth to be treated.
• the distribution of the beams can be done from pre-cut wires and then the distribution machine is similar to a seed drill or else with a mobile cutting machine equipped with a device for regular distribution. beams.
• the mixing operation it consists in working the soil to the depth chosen to distribute the fibers previously deposited on the surface. For this, a harrow or preferably a rotary machine such as a ROTOVATOR cutter is used.
• the three operations which require suitable equipment can be carried out separately or in a single operation with associated machines using a single means of movement (tractor).
• a variant of the previous process has been developed for repairing gravel pavement layers treated with hydraulic binders.
• the gravel is extracted by reducing them to their granular constituents (the gravel) and powders (the pulverized binders) and they are mixed with the fibers of the invention by adding water and the new hydraulic binders before replacing the material with its original location.
• the first method which has been described in detail applies as such to the production of road or motorway sub-layers and more precisely of form layers, that is to say, of the first layer deposited on the same the leveled ground.
• the same process easily adapts to other road sub-layers such as for example the foundation, that which rests directly on the form layer, or on the base layer.
• Mobile processes are more suitable for localized sites where it is the granular material of the soil itself which needs to be stabilized and for the reprocessing of degraded pavements.
• a mobile machine is preferably used.
• the functions are successively: extraction of the existing layer after milling, addition of the fiber and binders then mixing in a mixer and finally placing the product mixed on the ground.
• the function of the methods according to the invention is to increase the "lift" of the powder or of the granular material used in the soils.
• the traditional way to improve the bearing capacity of a given material such as general purpose sand consists in adding to it determined quantities of a sand of well defined particle size which is called a corrective sand.
• the addition of the fibers according to the invention makes it possible to significantly reduce or even in certain cases, to eliminate the addition of corrective sand to achieve a given lift.
• the lift of sands treated with a hydraulic binder is evaluated using a standard quantity (NF-P-98 231.4), the immediate lift index (I.P.I.).
• the test to determine it consists in pressing a punch of determined shape to push it of a given depth (2.5 mm) into the material to be tested. The measurement is that of the force necessary to obtain the insertion, it is proportional to the pressure on the face of the punch.
• the fibers make it possible to increase the I.P.I. at least 10 points.
• the quantities of hydraulic binder when it is present are more or less important, if they are zero or remain low, the bundles of filaments made of the usual glass intended for reinforcement of plastics or the production of textiles are suitable, these are, for example, glass strands of the STABI-FIL type made from a traditional glass for the reinforcing fiber known as “E glass”.
• Hydraulic binders have a well-known characteristic, their removal during hardening ("setting"). For these binders to be effective, they must remain compact, that their cracking is absent or at least, remains limited.
• test consists in determining the time formation of a crack and its width on test pieces of normal paste, in the shape of a ring, stored under the defined conditions.
• the test piece consisting of the reinforced sand mixture and the binder is poured into a cylindrical mold with vertical axis (diameter 127 mm) comprising a coaxial cylindrical steel core (diameter 90 mm).
• the test pieces are kept in a humid cabinet before demolding and in the air after demolding, demolding takes place after 24 hours. It operates by moving the two halves of the mold away from each other.
• the test tube is preserved with its nucleus.
• Two measurements relate to 3 identical test pieces for a given material.
• the first consists in noting the time elapsed between the instant of demolding and that when a crack occurs, the second, in observing the evolution of the width of the cracks.
• the test report gives the three values observed each time.
• the reinforcing glass fibers it was either STABI-FIL or CEM-FIL (alkali resistant) in both cases in the form of a wick of 2400 tex with filaments with a diameter of 14 ⁇ m, the cutting the wick was made in sections of 6 or 25 mm.
• the fiber content of the sand was 0.1 and 0.2%, respectively.
• the results are represented figure 2 for the delay before the appearance of the first crack and figure 3 for the width of this one. For each composition, the three results of the three test pieces produced are shown. In Figure 2, we see at 11 the number of days after which the crack appeared.
• the arrows 12 indicate that at the twenty-eighth day, no crack was visible.
• the technique of the invention makes it possible to improve mechanical performance, in particular the bearing capacity of soils whose sub-layers are based on powders or granules such as, for example, pulverulent natural materials containing organic products.
• This technique is particularly interesting for the use of industrial by-products.
• slag which results from the manufacture of metals from their original ores, such as blast furnace slag, as an undercoat.
• the addition of less than 0.1% of textile glass filaments associated by 40 or more makes it possible to make the pulverulent material sufficiently stable to give it the stability necessary for the production of road sub-layers or of various terrains, sports grounds, racetracks, fairgrounds, etc.
• incineration bottom ash or fly ash in particular silico-aluminous which. are by-products of the industry which in general only serve to clutter the quarries can, thanks to the invention, find a use and thus be valued.
• any powdered or granular material of organic or non-organic nature is subject to the process of the invention. This is particularly the case for residues from the treatment of household waste.
• the technique of the invention makes it possible to reuse the bass treated with hydraulic binders by limiting the external contributions of new materials.

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• Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Civil Engineering (AREA)
• Environmental & Geological Engineering (AREA)
• Agronomy & Crop Science (AREA)
• Architecture (AREA)
• Soil Sciences (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Mining & Mineral Resources (AREA)
• Paleontology (AREA)
• General Engineering & Computer Science (AREA)
• Road Paving Structures (AREA)

Applications Claiming Priority (7)

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• 1994
  • 1994-04-15 FR FR9404489A patent/FR2705977B3/fr not_active Expired - Fee Related
  • 1994-06-01 US US08/549,787 patent/US5683208A/en not_active Expired - Fee Related
  • 1994-06-01 BR BR9406781A patent/BR9406781A/pt not_active Application Discontinuation
  • 1994-06-01 AU AU69318/94A patent/AU680003B2/en not_active Withdrawn - After Issue
  • 1994-06-01 WO PCT/FR1994/000643 patent/WO1994028248A1/fr not_active Application Discontinuation
  • 1994-06-01 CA CA002163999A patent/CA2163999A1/fr not_active Abandoned
  • 1994-06-01 EP EP94917704A patent/EP0702738A1/fr not_active Withdrawn
  • 1994-06-01 JP JP7500327A patent/JPH09501996A/ja active Pending
  • 1994-06-02 IL IL10987794A patent/IL109877A0/xx unknown

Non-Patent Citations (1)

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