WO2008037911A2 - Composition of rolled and compacted concrete reinforced with fibres and including bituminous chippings and method for making a pavement using said composition - Google Patents

Abstract

The invention relates to a composition of rolled compacted concrete reinforced with fibres that comprises granulates, a hydraulic binder and metallic fibres, the hydraulic binder content ranging from 150 to 400 kg per cubic metre of concrete, the water content ranging from 90 to 160 litres per cubic metre of concrete, characterised in that said granulates include bituminous drilled fragments, the metallic fibre dosage not exceeding 25 kg per cubic metre of concrete.

Description

 FIBER-REINFORCED COMPACT ROLLER CONCRETE COMPOSITION COMPRISING BITUMINOUS FRAISATS AND METHOD FOR PRODUCING A PAVEMENT

The present invention relates to a compacted rolled concrete composition reinforced with metal fibers and containing a variable proportion of recycled bituminous materials resulting from the deconstruction of roadways, as well as to a process for producing continuous pavements or industrial areas without attached from this composition. To achieve a sustainable pavement seamless cast concrete seamless, it is known a method, said continuous reinforced concrete process (BAC), in which steel bars, generally 16 mm in diameter, are connected to each other in continuous over the entire length of the roadway. Once the steel bars are laid, the concrete is applied, usually using a slipform machine. Continuous reinforced concrete, however, remains a heavy technique to implement and expensive.

Compared with poured or unsaturated concrete, compacted rolled concrete compositions allow, for at least equal mechanical performance, a reduction in the cement content of the order of 20% because of both a reduction in the order 15% of the water content and also a higher density obtained by compaction with heavy equipment (and not by a mere pervibration with vibrating needles). The lower water content makes it possible to use the material with an asphalt paver finisher, then compact it with a heavy vibratory compactor and a tire compactor usually weighing 3 tonnes per wheel. The compacted rolled concrete has the advantage of an immediate lift which allows the traffic of the construction trucks: thus it is possible to implement the bituminous wearing course as soon as the compaction of the compacted concrete is finished, which makes it possible to open the pavement to the circulation as soon as the bituminous mix is cooled, that is to say after a very short delay of the order of 4 hours. By comparison, the consistency of the pervious cast concrete requires an implementation with the traditional techniques of slipping machine or vibrating rule and not allows re-circulation until after a sufficient setting time which is usually 7 days.

In the two types of conventional concrete mentioned above, it is known to insert metal fibers. The metal fibers used in perverted concrete in industrial slabs are most often drawn fibers, in particular hook fibers such as those marketed by Bekaert under the trademark "Dramix", corrugated fibers such as those marketed by the company. Trefil Arbed or the total anchored fiber marketed under the trademark "Twincone" by Trefil Arbed.

After reinforcement with steel fibers, the traditional concretes, which are perforated or cast, make it possible to produce industrial pavements (often covered and thus less exposed to weather and temperature variations than pavements) of large dimensions up to 2,000 m without joints. , the mechanical properties of the fibers to space the joints. On the other hand, these concretes have not hitherto been used effectively for the manufacture of continuous pavements without joints, despite the interest presented by such an application. Indeed, relatively high dosages of cement and water generate in these concretes a hydraulic shrinkage to which is added the thermal shrinkage. The mechanical stresses are such that the fibers can not control them. As a result, the phenomena of shrinkage of the concrete lead to a much greater cracking than pavements, with an unacceptable degree of opening more than 1 mm of opening. Thus, it is necessary to practice joints in these fiber reinforced concrete pavements in order to locate the effects of the shrinkage and to reduce the crack openings, which makes lose the economic benefits of a continuous pavement and considerably hinders the development of pavements. made of fiber-reinforced, corrugated cast concrete.

The document EP 1 278 925 describes a compacted rolled concrete composition reinforced with metal fibers, for the realization of a continuous road without joint which offers good properties in terms of the number of cracks and control of the opening of these cracks. This composition comprises metal fibers of a particular type, at a dosage of 30 kg to 40 kg per cubic meter of concrete. Metal fibers are described in detail in this document and may be defined by the fact that they consist of substantially cylindrical son having a substantially straight longitudinal central portion extending on each side through a spacer portion of a portion of curved end whose shape is of the type which prevents the attachment of two neighboring fibers, said threads having a diameter of between 0.38 and 1.05 mm, a total length of between 19 and 80 mm, a length of the parts of end between 1.5 and 4 mm, a transverse offset between the central portion and each end portion of at least 0.75 mm, an obtuse angle of not more than 160 ° between each intermediate portion and the central portion , an obtuse angle between each intermediate portion and end portion, a minimum tensile strength of 900N / mm2.

These metal fibers have a relatively high cost of the order of 1000 € per ton. The fiber dosage therefore has a significant impact on the final cost of the concrete composition.

Moreover, it is known that, as soon as a roadway begins to show significant degradation by mechanical fatigue of the bound materials, it is necessary to carry out a heavy maintenance operation which can be either reinforcement by adding materials. additional, if at least the constraints of the site allow it, a partial or total reconstruction at the same altimetric level, especially in the case of the presence of bridges that do not allow to elevate the road or urban site. The partial or total reconstruction of the roadway requires, beforehand, a deconstruction operation called milling (or planing) existing materials with very powerful machines capable of working to a depth exceeding 30 cm. The planed elements, called costs, are therefore constituted in variable proportions, depending on the case and the type of pavement, bituminous materials from the wearing courses and basecoats of pavements, and possibly from materials treated with hydraulic binders from pavement foundation layers. Bituminous blasting thus comes from the deconstruction of bituminous pavements for which the original material was manufactured in hot asphalt plants, with a bitumen dosage generally between 4.2% and 5% of the weight of aggregates. Bituminous blasting is therefore composed of natural aggregates which remain coated with a film of bitumen.

It is known that bituminous blotches can be partially recycled for the manufacture of bituminous mixes in hot-mix asphalt plants, but generally at a maximum rate of 25% in most existing installations, with higher rates being possible. achieved with particular technologies, to date with a maximum of 35% to 50%. Indeed, the introduction of spoilage firstly poses material problems related to hot-dip tube technology and the limits of the corresponding device called ring recycling. In addition, the heating of the costs entails an aging of the bitumen whose mechanical properties are thus degraded. As a result, the quality criteria for the manufacture and implementation of hot-mix asphalt usually limit the maximum amount of recycled bituminous paste in the final mixture to a maximum of 25%. This means that the manufacture of hot mix asphalt requires at least 50% new aggregates, from quarries, and most often at least 75%. In France, bitumen production from pavement deconstruction is estimated at at least 2 million tonnes per year, of which about 50% is recycled. In many other countries, the practice of recycling is less widespread than in France because of the difficulty of managing the various constraints related to the collection and transport of the costs to the coating stations. The international result, for example in China where pavement structures built in the last ten years have been undersized and require generalized deconstructions / reconstructions, particularly on the existing motorway network, is an accumulation of tens of millions of tons of expenses. These materials, however manufactured with new aggregates of high quality, are not valued but are simply deposited, at best on storage areas set up near pavement reconstruction sites, and at worst in landfill. With a composition of bituminous and new aggregates, the presence of bitumen which coats the natural aggregates, in the mixing part of the mixture, causes significant modifications of the bonds related to the hydraulic setting of the binder. In fact, the setting grows then, not only between aggregates as in the case of traditional concretes, but also partly between the bitumen films coating the mills or between a film of bitumen and a new aggregate. The mechanical characteristics of the bitumen film thus provoke a viscoelastic effect comparable to that found in traditional bituminous materials and give the composition a relative flexibility, as opposed to the much more rigid hydraulic connections observed in cement concretes. This is why the modulus of elasticity characterizing the stiffness of the material obtained is significantly lower in the case of compositions containing bituminous blast, compared with the cast concretes pervérés or compacted rolled concrete containing only new aggregates. Patent EP 1 634 858 discloses the introduction of bituminous blast in traditional concretes. Similarly, tests for producing a continuous pavement seamless with a pervious cast concrete composition comprising between 10% and 90% of bituminous blasting were carried out. However, these tests did not give satisfactory results because of the appearance of cracks in number and opening incompatible with a good behavior of the roadway in time under heavy traffic. These tests were carried out with the use of a pervious poured concrete and a formulation adapted to the implementation with a slip-form machine, that is to say with high dosages in water and hydraulic binder. which generate a strong cracking as seen previously. Consequently, in order to be able to produce continuous pavements without joints with this type of composition, it is necessary to add metal reinforcements making it possible to control the cracking, which leads to the use of the expensive and cumbersome technique to be implemented. continuous reinforced concrete.

The object of the invention is to provide a compacted rolled concrete composition containing bituminous blast which does not exhibit, at least, some of the aforementioned disadvantages of the prior art.

Another objective of the present invention is that the composition can be implemented with the asphalt mix application workshops, that is to say, finisher and compactors. The reference in terms of evaluation of the control of cracking is the Technical Guide for the Maintenance of Concrete Pavements, published by the Roads and Highways Technical Service associated with the Central Bridges and Roads Laboratory (October 2002), which provides for different severity levels for slab beats measured between crack edges. The beat is measured under the passage of a 13-tonne axle with roadside equipment called the Lacroix deflectograph. Level 1, corresponding to the lowest severity for which no maintenance intervention is required, is set at a beat threshold of less than 20 hundredths of a millimeter. The experience of pavements in service under heavy traffic shows that this level of slabbing can only be obtained for cracks whose opening is less than 1 millimeter: in this case, the load transfer between the edges of cracks is ensured. by the aggregates meshed in the crack, and not by the steels in the case where one is in the presence of a continuous reinforced concrete or a compacted rolled concrete reinforced with steel fibers according to the document EP 1 278 925.

For this, the invention provides a fiber-reinforced compacted rolled concrete composition comprising aggregates, a hydraulic binder and metal fibers, the hydraulic binder content being between 150 and 400 kg per cubic meter of concrete and the water content being between 90 and 160 liters per cubic meter of concrete, characterized in that said aggregates comprise bituminous blotches, the dosage of metal fibers being at most 25 kg per cubic meter of concrete. The metal fibers are those described in EP 1 278 925, that is to say that they consist of substantially cylindrical son having a substantially rectilinear longitudinal central portion extending on each side via a intermediate portion of a curved end portion whose shape is of the type which prevents the attachment of two adjacent fibers, said wires having a diameter of between 0.38 and 1.05 mm, a total length of between 19 and 80 mm, a length of the end portions between 1.5 and 4 mm, a transverse offset between the central portion and each end portion of at least 0.75 mm, an obtuse angle of not more than 160 ° between each intermediate portion and the portion central, an obtuse angle between each intermediate portion and end portion, a minimum tensile strength of 900 N / mm ² .

This composition makes it possible to recycle, in the cold, a high proportion of bituminous mix and thus requires only a limited consumption of new aggregates coming from the quarries. In addition and as compared to bituminous materials manufactured in the HMA positions at a temperature generally on the order of 150 ⁰ C, without heating the aggregates in the present composition avoids the corresponding consumption of fuel or of natural gas. Finally, with this composition, a fiber dosage of less than or equal to 25 kg per cubic meter of concrete is sufficient to achieve the objective of satisfactory charge transfer and controlled cracking with a crack opening of less than 1 millimeter, without which it is necessary to implement the technique of continuous reinforced concrete. Advantageously, the dosage of metal fibers is between 20 and 25 kg per cubic meter of concrete.

Preferably, the aggregates comprise between 10% and 90% of bituminous straws. According to a particular embodiment, the granular mixture comprises at least 40% of bituminous drums. In one embodiment, said aggregates comprise between 0% and 50% corrector sand.

In one embodiment, said aggregates comprise between 0% and 50% of crushed cement concrete resulting from the demolition of pavements, buildings or various works. Preferably, the composition has a content of plasticizer adjuvant and / or retarder at most equal to 1, 8% by weight of hydraulic binder.

The concrete composition according to the invention offers a particularly advantageous behavior in terms of control of cracking. Specifically, the spacing between cracks is generally greater than 20 meters and the opening of these cracks varies between 0.2 mm and 1 mm maximum. Such cracking behavior allows good load transfer between cracks edges and thus avoids damage related to the so-called slabbing phenomenon frequently found on perverted concrete pavements. The invention also provides a method for producing continuous pavements or industrial areas without joints, characterized in that it comprises the step of producing a compacted rolled reinforced concrete layer of fibers from the composition according to the invention above.

For example, the method can be realized:

either by a continuous concrete batch plant and the metal fiber dosing means both described in the document EP 1 324 865. In this case, the implementation of the material thus manufactured is carried out with a bituminous mix workshop comprising a paver and compactors;

- or by recycling in place of the pavement on site.

Preferably, the on-site recycling comprises the steps of: - spreading metal fibers and a hydraulic binder on a road to be reconstructed comprising a bituminous material;

milling said roadway to be reconstructed, so as to obtain a composition comprising bituminous blasting agents, a hydraulic binder and metal fibers; kneading and then compacting said composition so as to obtain said compacted rolled concrete layer.

According to these characteristics, on-site recycling of the bituminous mix is carried out, which has the advantage of limiting both the consumption of new aggregates, the quantity of material to be transported and the storage or disposal of the constituent materials of the existing roadway.

In one embodiment, the method comprises the step of adding new aggregates, mills or recycled aggregates in the materials spread on the road to be rebuilt, in a proportion of between 10% and 90%.

In one embodiment, the new aggregates comprise a correction sand.

In one embodiment, the aggregates added comprise a proportion of crushed cement concrete from the demolition of pavements, buildings or various works. The invention will be better understood, and other objects, details, features and advantages thereof will appear more clearly in the following description of a particular embodiment of the invention, given solely for illustrative purposes and not limiting, with reference to the accompanying drawings.

In these drawings, FIGS. 1 and 2 are graphs showing the evolution of the mechanical properties of compositions according to embodiments of the invention, as a function of the rate of bituminous blasting.

In the context of the present invention, different compositions of perverted cast concrete and compacted rolled concrete have been studied according to Table I, with for each composition a grain size curve adjusted to the average curve given by the specification zone of the French NF standard. P 98-128.

Table I The study illustrated in Table I only deals with concrete matrices before the introduction of metal fibers, in order to isolate the phenomena related to the action of the bituminous mix in the aggregate mixture. However, the compositions 2, 3 and 4 are formulated for the use of the metal fibers described in the document EP 1 278 925 and sold in particular by the company Bekaert under the trademark "Dramix 80/60".

In the case of compositions 1, 2 and 3, the new aggregates are chippings with a granularity of 6/10 mm and 10/14 mm, with the addition of a 2/6 mm sand and a corrective sand 0 / 4 mm. Corrective sand is a rolled river sand that serves both to optimize the grain size curve according to the French standard NF P 98-128 and to facilitate the compaction of the final material on site, the aim being to obtain the highest density possible for an increase in resistance. In the case of composition 4, the new granulate is the same 0/4 mm corrector sand as for compositions 2 and 3; bituminous drums come from a stock on a coating station, the granularity being 0/10 mm.

In each of the above compositions, a CEM II / B 32.5 cement was used as the hydraulic binder. The proportion of plasticizer / retardant admixture is 0.4% of the weight of the cement.

Compositions 1 and 2 do not include bituminous blotches and are given for reference. The composition 1 is a pervious cast concrete and the composition 2 is a compacted rolled concrete comprising a lower water dosage of 45 liters relative to the composition 1, a reduction of the water content of 28%. The study illustrated in Table I thus confirms that, despite a lower cement dosage of 50 kg, a reduction of 15%, the resistance of the compacted rolled concrete, that is to say 4.5 MPa, is greater 25% to that of perverted cast concrete which is 3.4 MPa.

Composition 3 comprises 40% of bituminous blot in a formulation of new aggregates of compacted rolled concrete, resulting in a bitumen content of 2.05% in the mixture thus obtained. With the same cement dosage as the composition 2, Table I shows that the strength of the composition 3 is 2.54 MPa, a decrease of 44% compared to the composition 2 whose resistance is 4.5 MPa . Similarly, the modulus of elasticity also decreases by about 50% by comparing the two compositions 2 and 3. At the same dosage cement, the introduction of bituminous blot in proportion of 40% in a mixture of new aggregates therefore leads to reduce both the resistance and the modulus of elasticity by a factor of the order of 2.

Composition 4 comprises 90% bituminous blotches, ie 4.6% bitumen, in compacted rolled concrete. At the same dosage cement that the composition 1 which contains 100% new aggregates, Table I shows this time a decrease in strengths and modulus of elasticity in a factor of 3.

Sizing calculations demonstrate that the decrease in the rigidity of the materials of compositions 3 and 4, in parallel with the decrease in their strength, makes it possible to reduce the tensile stress by flexing under heavy loads and thus to maintain the same thickness of material as in the case of composition 2 which comprises 100% new aggregates.

It is known, in the French method of sizing pavements and through numerous cross-international studies, that bituminous pavements in wearing course, manufactured with 5% of grade 60/70 bitumen, have a modulus of elasticity in the range of 5,000 to 6,000 MPa at a temperature of 15 ° C and a dynamic test frequency of 10 Hz. Similarly, the low-bitumen manufactured at 4.2% or 4.5% of bitumen and used as a basecoat pavement have a module of the order of 9 000 MPa under the same test conditions. Also known are high modulus bituminous mixes which are manufactured with 35/50 grade hard bitumens or with modified bitumens, for example by polymers. With modules of the order of 14,000 MPa under the above test conditions, high-modulus asphalt pavements reduce pavement base layer thicknesses because of their higher stiffness than conventional low-density asphalt pavements. .

FIGS. 1 and 2 of the accompanying drawings show the respective evolutions of the splitting resistances and the modulus of elasticity (in static compression at a temperature of 20 ^° C.) of the various compositions 2 to 4 of the aforementioned Table I, as a function of the bituminous paste content. At the reserve near test conditions which are not exactly the same in both cases but remain comparable, we note that a compacted rolled concrete dosed at 280 kg of cement and containing from 60% to 70% of bituminous drums, a bitumen content of the order of 3% to 3.5%, has a modulus of elasticity, so a stiffness, close to that of a high-modulus bituminous mix generally dosed at 5% of bitumen. This result is unexpected because according to the invention there is obtained a hybrid material, formulated with a relatively strong cement dosage and containing relatively little bitumen, which nevertheless shows a viscoelastic mechanical behavior close to that of a high modulus bituminous mix.

Mechanically speaking, the material according to the invention is interesting because it has the same structural power, at the same time:

- a compacted rolled concrete manufactured with new aggregates,

- and also a high-modulus asphalt mix, which is, to date, the most structurally efficient product among all the existing bituminous materials.

The composition described in document EP 1 278 925 gives good results in terms of controlling cracking of pavements for a fiber dosage of the order of 30 to 40 kg per cubic meter of concrete. However, a correlation has been observed between the stiffness of a material treated with a hydraulic binder (cement or blast furnace slag in particular) and its cracking behavior in pavements in service, with a decrease in cracking which is parallel to the decrease in the modulus of elasticity of the material. In the case of the present invention and compared with compacted rolled concrete manufactured with new aggregates described in EP 1 278 925, the introduction of bituminous blast, the viscoelastic nature of the final material and the corresponding reduction of the modulus of elasticity in the composition thus obtained result in a significant reduction in the number and openings of cracks.

This is demonstrated in situ in pavement behavior at cracking. Indeed, for a fiber dosage of 30 kg per cubic meter of concrete, auscultations carried out on the sites in service since the year 2000 show that the compositions dosed at 280 kg of cement per cubic meter of concrete manufactured with new aggregates described in the aforementioned document EP 1 278 925 give results satisfactory in terms of control of pavement cracking, that is crack openings less than 1 mm and beats less than 20 hundredths of a millimeter between cracks edges below the axle of 13 tons. However, with a 4 cm thick (35/50 bitumen grade) bituminous concrete surfacing covering these compositions of EP 1 278 925, most of the cracks traversed the bituminous wearing course and appeared visible on the surface of the roadway at the end of the first winter following the implementation of the said composition. By comparison, in the case of the present invention, with the same cement dosage of 280 kg and the same quality of cement as in the above example according to EP 1 278 925 but with a fiber dosage limited to only 20 kg per cubic meter of concrete, the sites made according to the above composition 3 of the present invention, that is to say with 40% of bituminous mix in the granular mixture, do not reveal any visible crack which, from the first winter, would have crossed the wearing course of only 2.5 cm of very thin asphalt concrete made with the same grade of 35/50 bitumen. These first field results confirm the experimental correlation between, on the one hand, the viscoelastic nature of a material containing at least 25% of bituminous aggregates treated with cement and, on the other hand, its cracking behavior. in the pavements. Other sites will be realized and auscultated, this time with compositions including higher rates of costs up to composition 4 above to 90% of costs. An ambitious research program, lasting four years, will start in France in autumn 2007 and includes laboratory tests in fatigue and dynamic module, an experimental section at the Manège de fatigue of the Central Laboratory of Roads and Bridges and a complete set of field auscultations. The purpose of this program is to precisely quantify the impact of the dosing of both bituminous blast and steel fibers on the mechanical performance of the material according to the present invention, as well as the control of cracking in the corresponding pavements.

From now on, field auscultations implementing the present invention, with the introduction of bituminous drums in the granular mixture, show the possibility of reducing the dosage. fiber and reduce it to 25 kg or even 20 kg per cubic meter of concrete. Despite the reduction in the fiber dosage, the result obtained on construction sites is at least as satisfactory, in terms of the number of cracks, crack openings and flapping of the edges of cracks, as that obtained with the compositions with new aggregates described in EP 1 278 925.

It is therefore considered that the introduction of 25% to 90% of bituminous paste in a compacted rolled concrete composition according to the document EP 1 278 925 makes it possible respectively to reduce by at least 15% to 30% the fiber dosage required to ensure satisfactory control of the cracking of the pavement material. Compared with competing techniques, a reduction in fiber dosage has significant economic effects that are favorable to the competitiveness of the final material thus obtained. It is also recalled that the present invention is part of a sustainable development approach by limiting both the sampling of new aggregates in the quarries, as well as the consumption of fossil fuel related to the transport and heating of bituminous drums in traditional techniques. hot coating.

Compositions 3 and 4 make it possible to produce a compacted rolled concrete layer for continuous pavements or industrial areas without joints. With these compositions, the thickness of the compacted rolled concrete layer is very close, within half a centimeter, to the thickness required for composition 2 described in document EP 1 278 925. For example, the thickness may be from 7 to 20 cm.

The compacted rolled concrete layer may be covered, for example, with a bituminous asphalt surface course selected, for example, for its ability to drain rain water and / or to limit the emission of noise.

Of course, the invention is not limited to compositions 3 and 4 above.

In particular, other types of hydraulic binder and new or recycled aggregates could be used, for example crushed cement concrete from the deconstruction of rigid pavements or other concrete structures. The levels of hydraulic binders, water and adjuvant can be modified, within limits allowing an implementation of the composition with the techniques generally used with compacted rolled concrete.

An example of a method for producing a seamless continuous roadway, using a composition according to one embodiment of the invention, is now described. Specifically, it is a pavement reconstruction process, with on-site recycling of bituminous blasting.

The fiber dosing means described in EP 1 324 865 can be installed on a self-propelled semi-trailer unit which allows it a high mobility. This is why the manufacture of the composition can be carried out using a recycling workshop in cold place of the roadway, by the use of the aforementioned dosing means for the fibers, associated with materials specifically adapted as for example the ARC 700 or the EMF 200 developed by the company Eiffage Travaux Publics or the MARINI CoId Recycler MCR 250 developed by the company FAYAT. These materials have the advantage of mobility while being equipped with a continuous mixer as that of the continuous plants described in the document EP 1 324 865. The judicious combination of these materials thus allows to obtain a good quality of mixing and drying. fiber integration for the manufacture and implementation of the aforementioned composition on the site of the building site, with the following realization steps: a. spreading of a corrective sand on the pavement to be recycled, using a sandblasting truck, the aim being to add an additional sandy fraction so as to obtain a granulometric curve making it possible to optimize the performance of the granular mixture treated with a hydraulic binder. The proportion of corrective sand is generally of the order of 10 to 20% in the granular mixture, which corresponds to a use of 80 to 90% of the materials of the site; b. spreading the fibers on the correction sand with the semitrailer assembly carrying the equipment described in document EP 1 324 865; vs. spreading of the hydraulic binder and the plasticizer-retardant additive described in EP 1 278 925. The spreading of the binder is carried out above the fiber-covered corrective sand layer, for example with ARC dosing equipment developed by the company Eiffage

Public Works or by a binder spreader for soil treatment in place; d. milling / planing of existing pavement previously covered with sand, fiber and hydraulic binder. Milling is performed on a variable thickness according to the sizing calculation of the roadway to be reinforced, for example using a machine marketed by Wirtgen. The milling operation can also be carried out for example with a material of the ARC 700 type of the company Eiffage Travaux

Publics, in which case this machine also ensures the mixing of the composition; e. mixing and implementation of the composition with, for example, EMF 200 material from Eiffage Travaux Publics or equivalent material such as MARINI CoId

Recycle MCR 250 from the company FAYAT; f. compaction of the composition using a heavy vibratory compactor and a tire compactor; boy Wut. spreading a gravel bitumen emulsion which serves as a curing product, in order to conserve the water necessary for the setting of the hydraulic binder in the composition. From this stage of realization, the recycled pavement can already support the traffic of trucks and construction machines; h. spreading a bonding layer composed of bitumen emulsion, in order to ensure the bonding of the wearing course to the layer made with the composition according to the invention; i. implementation and compacting of the bituminous wearing course which may be for example a very thin or thin mix of respectively 2.5 cm or 4 cm thick, with possible phonic qualities to reduce the emission of rolling noise, or a draining asphalt to prevent splashing of rainwater by traffic.

Steps a. have. above ground recycling can be carried out successively without waiting time between them, this due to the immediate lift of the material according to the composition of the present invention, a material that allows the circulation of trucks and construction equipment for the implementation of the bituminous wearing course. The pavement thus recycled can therefore be opened to traffic as soon as the wearing course is cooled, that is to say about half a day after the application of the latter. The recycling in place also has the advantage of limiting transportation costs and fuel consumption by avoiding the displacement, by trucks, of the materials to be recycled to the plant and then their return to the site.

Although the invention has been described in connection with a particular embodiment, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Claims

1. Fiber-reinforced compacted rolled concrete composition comprising aggregates, a hydraulic binder and metal fibers, the hydraulic binder content being between 150 and 400 kg per cubic meter of concrete, the water content being between 90 and 160 liters per cubic meter of concrete, in which the metallic fibers are constituted by substantially cylindrical threads comprising a substantially rectilinear longitudinal central portion extending on each side by means of an intermediate portion of a curved end portion of which the shape is of the type which prevents the attachment of two adjacent fibers, said threads having a diameter of between 0.38 and 1.05 mm, a total length of between 19 and 80 mm, a length of the end parts lying between 1.5 and 4 mm, a transverse offset between the central portion and each end portion of at least 0.75 mm, an obtuse angle less than or equal to 160 ° e each intermediate portion and the central portion, an obtuse angle between each intermediate portion and end portion, a minimum tensile strength of 900 N / mm ² , characterized in that said aggregates comprise bituminous blotches, the proportioning metal fibers being not more than 25 kg per cubic meter of concrete. 2. Composition according to claim 1, wherein the dosage of metal fibers is between 20 and 25 kg per cubic meter of concrete. 3. Composition according to one of claims 1 to 2, wherein said aggregates comprise between 10% and 90% of bituminous straws. 4. Composition according to claim 3, wherein said aggregates comprise at least 25% of bituminous straws. 5. Composition according to one of claims 1 to 4, wherein said aggregates comprise between 0% and 50% correction sand. 6. Composition according to one of claims 1 to 5 wherein said aggregates comprise between 0% and 50% of crushed cement concrete from the demolition of pavements, buildings or various works. 7. Composition according to one of claims 1 to 6 having a content of plasticizer adjuvant and / or retarder at most equal to 1, 8% by weight of hydraulic binder. 8. A method of producing continuous pavements or industrial areas without joints, characterized in that it comprises the step of producing a layer of compacted rolled concrete reinforced with fibers from the composition according to one of the Claims 1 to 7. 9. The method of claim 8, wherein said composition is manufactured in a mixing plant. The method of claim 8, comprising the in-place recycling steps of: - spreading metal fibers and a hydraulic binder on a road to be rebuilt comprising a bituminous material, milling said roadway to be reconstructed, so as to obtain a composition comprising bituminous drums, a hydraulic binder and metal fibers, kneading and then compacting said composition so as to obtain a continuous pavement layer without joint. The process according to claim 10, comprising the step of adding new aggregates, mills or recycled aggregates in the materials spread on the road to be reconstructed, in a proportion of between 10% and 90%. The method of claim 11, wherein said new or recycled aggregates comprise a correction sand. 13. The method of claim 11 and 12, wherein said recycled aggregates comprise crushed cement concrete from the demolition of pavements, buildings or other works.