Classifications

• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
  • E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
  • E04C5/01—Reinforcing elements of metal, e.g. with non-structural coatings
  • E04C5/012—Discrete reinforcing elements, e.g. fibres

Definitions

• the present invention relates to a compacted rolled concrete composition reinforced with fibers and to a process for producing continuous pavements and industrial areas without joints, from said composition.
• compositions of rolled compacted concrete differ from conventional poured or spoiled concrete by the fact that, for similar mechanical properties, they require a reduced cement dosage as well as a reduced water content. This lower water content makes it possible to obtain sufficient bearing capacity to implement the material with road vehicles in order to compact it using a vibrating compactor and a tire compactor, then to return it to circulation without delay.
• the consistency of poured concrete requires implementation with traditional techniques of sliding formwork machine or vibrating rule and allows recirculation only after a sufficient setting time which is generally at least 7 days.
• metallic fibers In the two types of conventional concrete mentioned above, it is known to insert metallic fibers.
• the metallic fibers used in industrial paving are most often drawn fibers generally comprising wires of 1 mm in diameter.
• the different existing fibers differ from each other by the type of active anchoring in the concrete matrix.
• There are fibers made with a so-called deformable anchor for example hook fibers such as those sold by the company Bekaert under the brand “Dramix” or wavy fibers such as those sold by the company Trefnox Arbed.
• This company also manufactures a fiber sold under the brand "Twincone” which has a non-deformable cone at each of its ends.
• This type of anchoring is much more rigid than the anchoring obtained by hooks or corrugations, hence its name of fibers with so-called total anchoring.
• concrete comprises, on the one hand, 5 to 10% of the weight of cement in ultra-fine fillers such as silica fumes, which makes it possible to fill the interstitial voids of the concrete.
• Continuous reinforced concrete which is the benchmark for continuous seamless concrete, has fine and close cracking.
• the cracks With compacted concrete reinforced with corrugated fibers, the cracks are spaced but wide.
• “Twincone” fibers When “Twincone” fibers are used, the sum of the crack openings is 30% less than that observed in the case of wavy fibers.
• the behavior of concrete reinforced with fibers with total anchoring is similar to that of continuous reinforced concrete, this fiber allowing an anchoring more efficient than that of corrugated fiber.
• the tests have shown that the evolution of cracks in compacted rolled concrete reinforced with "Twincone” fibers is equivalent to that of cracks in continuous reinforced concrete.
• FIG. 1 of the appended drawings illustrates the results of a comparative pull-out test (“Pull-out test”) of a “Twincone” fiber A with total anchorage and of a fiber with deformable anchorage B, the two fibers with an identical diameter of 1 mm.
• Pull-out test a comparative pull-out test
• the use of fibers with total anchorage is necessary for the production of continuous pavements without joints, these making it possible to better limit the opening of the cracks.
• patent application FR 2 684 397 defines a concrete composition for making seamless pavements, having a determined composition which includes fibers with non-deformable anchoring such as those described in European patent applications EP 130 191 and EP 098 825.
• the compacted rolled concrete reinforced with fibers according to the invention comprising aggregates, a hydraulic binder and metallic fibers with deformable anchoring, is characterized in that the metallic fibers consist of wires substantially cylindrical comprising a substantially rectilinear longitudinal central portion extending on each side by means of an intermediate portion of a curved end portion whose shape is of the type which prevents the attachment of two neighboring fibers, said threads having - a diameter between 0.38 and 1.05 mm,
• composition comprising a content of hydraulic binder of between 180 and 400 kg per cubic meter of concrete , a water content of between 90 and 150 liters per cubic meter of concrete, a dosage of metallic fibers of between 25 and 60 kg per cubic meter of concrete, and a content of plasticizer and / or retarder adjuvant at most equal to 1, 8% by weight of the hydraulic binder.
• the hydraulic binder consists of a combination, in variable proportions, of clinker, ground slag, fly ash, gypsum (phosphogypsum or anhydrite) and ultrafine (silica fumes, pozzolans) .
• the fibers which have been selected in the present invention, to be inserted into a composition of compacted rolled concrete have led to better results in terms of limitation and control of cracking.
• the use of fibers as defined above, having curved end portions, substantially cylindrical over the entire length, in a composition of compacted rolled concrete surprisingly, achieves a fair balance between limiting the number of cracks and limiting the opening of the cracks present.
• Fibers with total anchoring or very rigid anchoring have a strong anchoring resistance up to a crack opening of 1 mm.
• the fiber according to the invention provides a strong anchoring effect, practically equivalent to that of the fiber with total anchoring.
• the performance of the anchoring is kept at much larger crack openings of up to 3 to 4 millimeters.
• the composition according to the invention has a much more secure ductility plateau than the breaking effect observed beyond 1 mm with a fiber with total anchoring, for example in the case of localized sagging of the platform. the roadway and a crack opening which could exceed 2 mm.
• the threads constituting the fibers have a diameter between 0.65 and 0.85 mm and a total length / diameter ratio between 65 and 85.
• the fibers have a total length / diameter ratio of the order of 80.
• each curved end part is formed of a rectilinear part connected to the central part by said inclined part comprising at least two elbows.
• the fibers used in the present invention are fibers of 0.75 mm in diameter, with a total length of 60 mm and with a tensile strength of at least 1100 N / mm 2 .
• This fiber also has the advantage, with an equal dosage by weight in concrete, of a number of fibers double that of the number of fibers of diameter of 1 mm traditionally used. Due to a hardening pushed further to the wire drawing, the thinner wire moreover has a higher elastic limit which makes it more efficient than a wire of 1 mm in diameter.
• the cracking observed in concretes obtained from the composition according to the invention remained limited to values between 0.3 and 1 mm.
• the aggregates of the concrete forming the irregular surface of the walls of the crack remain embedded between them and maintained in position, the effect of embedding being ensured by the fibers anchored in the matrix of the concrete on both sides of the crack .
• This mutual locking of the aggregates with one another and of the fibers which ensures a "seam" of the edges of the crack means that the crack thus controlled does not significantly weaken the overall structure of the pavement.
• the crack is not active, in the sense that it does not evolve under the constraints of heavy traffic during the service life of the roadway.
• the edges of the crack remaining mechanically embedded by the intergranular contacts between the constituents of the concrete the fibers are consequently less stressed in fatigue, which ensures good durability of the pavement.
• the aggregates used comprise from 70 to 100% of crushed material, having sharp angles and a shape close to the square, and a particle size between 0 and 14 mm so as to avoid the phenomena of segregation, that is to say of separation of large elements.
• the concrete composition also preferably includes a plasticizing aid which facilitates compaction by intergranular lubrication and makes it possible to obtain a density close to 2400 kg / m 3 of concrete with favorable consequences, such as higher strength and the possibility of reducing dosing with hydraulic binder
• the optimal water content is determined by the Modified Proctor test and varies between 4 and 6% of the dry constituents of the concrete.
• the composition comprises a content of hydraulic binder in the region of 250 to 300 kg per cubic meter of concrete, a water content of 4 to 6% of the weight of the dry constituents of the concrete, ie approximately 100 to 150 liters of water per cubic meter. of concrete, a dosage of metal fibers between 25 and 50 kg, preferably between 30 and 40 kg, per cubic meter of concrete.
• the composition includes 280 kg of hydraulic binder and 110 liters of water per cubic meter of concrete.
• the content of adjuvant is at least equal to 0.3% of the weight of the hydraulic binder.
• plasticizer for example 0.3 to 0.5% of the weight of hydraulic binder.
• the setting effect of the concrete insofar as the same product is used for the plasticizing and retarding effect, can only be obtained with higher dosages of plasticizer, for example at least 0.7 % of the weight of hydraulic binder if you want to keep the workability of the fresh concrete for about 20 hours, for example for a recovery the next day on the concrete of the day before.
• the concrete composition according to the invention can be used for the production or reinforcement of road structures or industrial areas having to support high rolling loads, such as those produced by frequent passages of trucks, heavy vehicles or large aircraft for example.
• composition according to the invention allows a layer of concrete having a continuously variable flexural strength over an extended crack opening range, for example from 0 to 4 mm, and without breaking the fibers.
• the variation in resistance over said range is less than 20% less than its nominal value.
• the processing of the material according to the invention is carried out by means of a heavy table finisher, which is a material generally used for processing bituminous materials, or by means of a grader.
• the concrete is then densified by a compactor of several tonnes comprising one or two vibrating rollers. This compaction can then be followed by a kneading effect provided by the action of a tire compactor applying for example a load of 3 to 5 tonnes per wheel.
• the fiber-reinforced compacted concrete can then be directly covered with a bituminous wearing course, the curing of the concrete can be carried out by an emulsion of gravel bitumen.
• a pavement consisting of a concrete base layer according to the invention, then covered with a bituminous wearing course has the advantage of a separation of functions, the cement concrete ensuring a long service life for the structure under heavy traffic, and bituminous mix making it possible to obtain a carpet having high specific qualities, for example a draining asphalt which absorbs rain water and / or an acoustic asphalt which limits rolling noise.
• the concrete layer can also be covered with a highly proportioned micro-concrete in cement, made up of a mixture of three components, namely cement, a fillerized sand (comprising a significant part of fine elements), and a sand containing little fine, fillerized sand comprising at least 10 to 20% of fine elements less than 0.080 mm.
• the rolled compacted concrete reinforced with fibers according to the invention can be used in reinforcing pavements. Simultaneously with reinforcement, this process can also resolve the problem of rutting of bituminous pavements by adding a thin layer of 5 to 18 cm, covered with a thin or very thin bituminous mix.
• FIG. 1 is a diagram illustrating the prior art and representing the results of tearing tests of a fiber with total anchoring and a fiber with deformable anchoring both having a wire diameter of 1 mm;
• FIG. 2 is a partial schematic side view of a fiber usable in a composition according to the invention.
• FIG. 3 is a diagram illustrating bending tests of several prisms obtained from a composition according to the invention in comparison with compositions according to the prior art.
• the composition according to the invention comprises metallic fibers constituted by wires 10 provided with curved end portions 12.
• the wires are substantially cylindrical over their entire length L and comprise a central portion 11 substantially rectilinear extending from each side by an inclined intermediate portion 13 which is extended by said part end 12.
• Each part 12 is formed of a rectilinear part connected to the central part 11 by said inclined intermediate portion 13 comprising at least two elbows.
• the wires have a diameter d of between 0.38 and 1.05 mm, a total length L of between 19 and 80 mm, and a minimum tensile strength of 900 N / mm 2 .
• the two end portions 12 of a wire can have a different or similar shape.
• the length £, V of the rectilinear parts of the end parts 12 may be different or similar and is between 1.5 and 4 mm.
• the inclined portion 13 of each end part forms with the rectilinear central part 11 an obtuse angle ⁇ or ⁇ ′ equal to or less than 160 °.
• the two angles ⁇ , ⁇ 'thus defined can be identical or different.
• One of the intermediate portions of an end portion is not necessarily in the plane formed by the other intermediate portion and the central portion 11. Furthermore, each end portion is not necessarily in the plane constituted by its intermediate part and the central part.
• the transverse offsets h, h 'between the central part 11 and each end part can be identical or different and are at least 0.75 mm.
• the composition according to the invention comprises fibers sold under the brand "Dramix 80/60".
• the fiber "Dramix 80/60” is a fiber which is characterized by a total length L of 60 mm for a diameter d of 0.75 mm, ie a ratio ⁇ of 80, and a tensile strength of at least 1100 N / mm.
• the two angles ⁇ ⁇ ' are substantially identical and the intermediate portions, the end portions and the central portion 11 are substantially in the same plane.
• compositions 1, 2 and 4 differ from each other only by the nature of the fibers that they contain.
• Composition 1 comprises “Twincone” fibers of the fully anchored type
• composition 2 comprises “Dramix FL 45/50” fibers of type with flattened hook ends
• composition 4 according to the invention comprises “Dramix 80 fibers”. 60 ".
• the fibers are dosed at 30 kg / m.
• Composition 3 comprises "Dramix FL 45/50" fibers like composition 2 but these are dosed at 35 kg / m 3 .
• the formulation of the concrete compositions has been defined so as to meet a criterion of compressive strength of the order of 50 to 60 MPa, while respecting the grading range in force for concretes compacted with a roller (NF P 98 -128).
• the compressive strength measured on cylinders of dimension 16x32 cm, in accordance with the standard in force, is given in table III. The tests were carried out on three concrete cylinders for each composition 1 to 4.
• FIG. 3 shows the results of the comparative bending tests carried out to assess the performance of the different fibers in controlling cracking of the concrete.
• Curves 1 to 4 correspond respectively to compositions 1 to 4 defined above.
• the appearance of the crack takes place under a load level of the order of 25 kN for the different compositions.
• the prism obtained with composition 1 comprising “Twincone” fibers has a pressure drop after the appearance of the crack up to approximately 0.2 mm of opening, then the fibers allow a resumption of effort. From a millimeter of crack in flexion, corresponding to the maximum bearing capacity, the fibers begin to break, which results in successive jumps of load and a very rapid decrease in the bearing capacity of the prism.
• the prism of composition 4 according to the invention exhibits a slight pressure drop at the appearance of the crack and then a resumption of effort.
• the maximum bearing capacity is obtained for a crack opening between 1 and 1.5 mm. The bearing capacity then decreases very gradually.
• composition 2 comprising "Dramix FL 45/50" fibers dosed at 30 kg
• the prism displays a very large pressure drop (of the order of 50%) after the appearance of the crack. Beyond a certain crack opening of the order of 1.8 mm, load jumps are visible on the curve. These jumps reflect fiber breaks as in the case of composition 1.
• composition 3 comprising "Dramix FL 45/50" fibers dosed at 35 kg
• the results are similar to those obtained with composition 2, only the increase in the dosage of fibers allows a higher load capacity.
• the capacity to recover from stress after cracking is substantially of the same order of magnitude for compositions 1, 3 and 4.
• the fibers have substantially the same potential with regard to cracking for openings restricted to 1 mm. Beyond this, the intrinsic behavior of the fibers, leading to rupture or tearing, modifies the behavior of a cracked section.
• the fully anchored fiber shows the strongest strength of the anchor up to a crack opening of 1 mm. However, if the crack opens further, there is a break in the fibers and a very rapid drop in the sewing effect of the edges of the crack.
• the fiber according to the invention shows a slightly lower anchoring resistance, of the order of 7%, than that obtained with a fiber with total anchoring.
• the performance of the anchoring is preserved at much larger crack openings ranging from 3 to 4 mm, which is not the case when using fibers with total anchoring or other fibers.

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• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Road Paving Structures (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Producing Shaped Articles From Materials (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Publications (2)

Family

ID=8849828

Family Applications (1)

Country Status (15)

Cited By (2)

Families Citing this family (8)

Family Cites Families (6)

• 2000
  • 2000-05-03 FR FR0005624A patent/FR2808522B1/fr not_active Expired - Fee Related
• 2001
  • 2001-04-27 ES ES01929737T patent/ES2217143T3/es not_active Expired - Lifetime
  • 2001-04-27 DE DE60102148T patent/DE60102148T2/de not_active Expired - Lifetime
  • 2001-04-27 EP EP01929737A patent/EP1278925B1/fr not_active Expired - Lifetime
  • 2001-04-27 SK SK1562-2002A patent/SK15622002A3/sk unknown
  • 2001-04-27 AT AT01929737T patent/ATE260386T1/de not_active IP Right Cessation
  • 2001-04-27 TR TR2004/01157T patent/TR200401157T4/xx unknown
  • 2001-04-27 AU AU2001256431A patent/AU2001256431A1/en not_active Abandoned
  • 2001-04-27 CZ CZ20023619A patent/CZ301483B6/cs not_active IP Right Cessation
  • 2001-04-27 CN CN01800007.XA patent/CN1122130C/zh not_active Expired - Fee Related
  • 2001-04-27 HU HU0300620A patent/HU223747B1/hu not_active IP Right Cessation
  • 2001-04-27 WO PCT/FR2001/001304 patent/WO2001054471A2/fr active IP Right Grant
  • 2001-04-27 PL PL359002A patent/PL206537B1/pl not_active IP Right Cessation
  • 2001-04-27 JP JP2001555463A patent/JP2003531794A/ja active Pending
  • 2001-05-02 BE BE2001/0294A patent/BE1014022A3/fr not_active IP Right Cessation

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