EP1012395A1

EP1012395A1 - Grid-type reinforcement for strengthening road structures, in particular made of bitumen

Info

Publication number: EP1012395A1
Application number: EP98942757A
Authority: EP
Inventors: Daniel Doligez
Original assignee: 6D Solutions
Current assignee: 6D SOLUTIONS
Priority date: 1997-08-25
Filing date: 1998-08-20
Publication date: 2000-06-28
Anticipated expiration: 2018-08-20
Also published as: FR2767543B1; AU748483B2; AU9077398A; BR9811358A; AU9078098A; WO1999010600A1; EP1009879A1; ATE281564T1; WO1999010601A1; CA2301741A1; FR2767543A1; EP1012395B1; DE69827398D1; PL339007A1

Abstract

The invention concerns a reinforcement (7) made basic to accelerate bitumen demulsification whereon it is set, and consisting of a fibreglass grid (22), a fine nonwoven (20) on its top surface and an incorporated heat-sealing product (21). Said reinforcement strongly prevents the bitumen from being thrust upwards under the weight of heavy-construction machines It also saves time and bitumen.

Description

REINFORCING REINFORCEMENT FOR ROAD STRUCTURES, ESPECIALLY IN BITUMEN

The present invention relates to the technical sector of public works, more precisely that of the construction and maintenance of roads, motorways, roadways, roadways and the like.

We know that the roads are coated with a layer of hydrocarbon materials often called "coated", or "bituminous concrete", this product coming from an oil residue (asphalt). More specifically, the pavements are in the general case (but not limiting) constituted by the support, in general a "coated", an emulsion layer above the support, as a bonding layer, a reinforcement of the type of 'invention above, and finally a new layer of asphalt about 4 to about 25 cm thick, in one or more layers separated by a thin layer of bonding emulsion.

Remember that a mix is a mixture of gravel and bitumen.

It has long appeared that it is necessary to reinforce such coatings, in particular to avoid the formation of cracks or cracks, due to the mechanical stresses exerted by road traffic, or to thermal stresses.

Various reinforcements have been incorporated into this bitumen wearing course, such as textile reinforcements (FR A 2 592 411, FR A 2 635 542), sheets of fiberglass, grid structures, or complex reinforcements associating a grid and a nonwoven tablecloth.

The products "ROADTEX" and "ROTAFLEX" (brands of the company CHOMARAT) are known. ROADTEX type structures consist of an open grid of continuous glass filaments linked by a thermoplastic polymer. ROTAFLEX type structures consist of a polyester nonwoven reinforced with a glass grid.

Patent EP 0 368 600 (Netlon Ltd.) describes a two-layer structure comprising:

a mesh grid above, in particular made of polypropylene, and comprising a thick nodule and not oriented at each junction of strands, and

a polyester fabric under the grid, therefore intended to come into contact with the bitumen layer deposited on the floor.

According to this document, an aqueous bitumen emulsion is deposited on the road, then the two-layer structure, then a new layer of bitumen. It is specified that the polypropylene of the grid undergoes a heat treatment during manufacture, to avoid shrinkage during the thermal shock caused by the deposition temperature of the mix.

An important feature of the Netlon patent is that the laminate is characterized in that the fabric is combined with the plastic mesh only at the thicker junctions of the mesh and not at the strands of the mesh.

EP 0 318 707 (Bay Mills Ltd.) is also known, which describes a frame for road surfaces, comprising:

- an open grid pre-impregnated with resin, with meshs kept open after impregnation;

an adhesive coating applied to the underside of the impregnated grid, without blocking the meshes.

It is specified that this adhesive coating can be activated by heat or pressure and forms a bond between the grid and the asphalt. This adhesive does not, however, bond the two layers of asphalt on both sides of the grid, which may also be suitable for certain road applications.

Patent USP 3,581,631 (Enka Corp.) describes an armature which consists of a film comprising threads or filaments, forming meshes which are completely or partially clogged with an adhesive. This adhesive is chosen from certain resins and certain polymers having a softening point greater than 50 ° C. and is cast hot on the film. The adhesive, on the one hand wets and "impregnates" the film, and on the other hand is miscible with the bitumen layer.

Finally, the combination of a ROADTEX product and a layer of hot-melt product applied to one of its faces is known, which melts at a temperature below that of the bitumen layer.

The documents of the prior art have sought to optimize the behavior of road structures.

The first problem is the need to perfectly bond the different layers forming the structure, that is to say the support (often a mix), the reinforcement and, in general, a top layer (often a mix applied hot to the whole).

There is a second problem, which follows from the first. Bitumen emulsions are manufactured in a plant, and consist of liquid or semi-liquid aqueous emulsions applicable by conventional equipment. These emulsions can break as well in 5 minutes as in several hours, depending in particular on the temperature prevailing on the application site. The quality of the bitumen is best adapted to the season and the region, but we cannot produce a different batch for each site temperature. After the deposition of a reinforcement, and as long as the emulsion is not broken, or even after the emulsion breaks if the site temperature is too high (bitumen too soft), public works machinery (which in particular must still deposit a layer of asphalt) cannot roll under penalty of seeing the bitumen stick to the wheels and under penalty of tearing off the reinforcement which has just been laid.

The object of the invention is to limit the rise of bitumen through the mesh of grid-type reinforcements.

Furthermore, it would be economically advantageous to reduce the amount of bitumen to be used. With a grid product such as ROADTEX, a conventional emulsion layer (water and bitumen in a weight ratio of approximately 40 - 60%) is deposited at the rate of approximately 500 g emulsion / m ² , ie approximately 300 g / m ² of "residual bitumen". With a grid + nonwoven product such as ROTAFLEX 833, a nonwoven at 80 g / m ^{2 is used} . We must then go up to about 500 g / m ² of residual bitumen, because it is necessary to impregnate the nonwoven. According to the invention, an objective is to be able, despite a complex structure comprising a nonwoven, to reduce the rate of residual bitumen to values of 300 g / m ² or even 200 g / m ² , that is to say - say below the usual dosages of the bonding layers. This reduction contributes to the reduction of the bitumen rise.

According to one of its main aspects, the invention resides in the combined use of a fusible product.

According to another of its aspects, the invention accelerates thanks to a basic treatment the speed of breakage or rupture of the bitumen emulsion, which reduces the downtime of the site and the rise of the bitumen (which is viscous) through the grid.

The invention applies to any road structure in the broad sense, including areas, runways, airports, etc. comprising at least one hydrocarbon binder, in particular so-called bituminous structures, in particular, but for illustrative purposes only, structures comprising at least minus one layer of asphalt or asphalt. According to a particular embodiment, the invention relates to a complex reinforcement for road surfacing of the coated or asphalt type, which comprises:

a grid

- a fine nonwoven deposited on the grid

a fusible product being interposed between the nonwoven and the grid so as to only partially cover the surface.

The invention therefore provides a three-layer structure where the nonwoven is only partially clogged with the fusible product in order to limit the rise of the bitumen.

The fusible product fulfills a second function, that of a bonding layer for the final bitumen layer (hot-coated) which will be applied subsequently to the assembly, which makes it possible to significantly reduce the dosage of the bitumen emulsion.

A preferred manufacturing process consists in preparing the fine nonwoven, and in "sprinkling" the fusible on the nonwoven. By "dusting" is meant the fact that, by any means of application known to those skilled in the art, the fusible is deposited so as to cover only part of the surface of the nonwoven. The dusting should be as regular as possible, but perfect regularity is not necessary. By "part of the surface" is meant the fact that about 30 to 70% of the surface of the nonwoven is covered. By "fine" nonwoven is meant a nonwoven of the order of 20 to 80, preferably 20 to 50, preferably 20 to 30 g / m ² .

It is also possible to deposit the fusible in the form of a perforated film, that is to say to partially close the openings or pores of the nonwoven. According to a particular and nonlimiting mode, the fusible product will be an EVA (ethylene / vinyl acetate) copolymer.

The grid is then deposited on the face of the nonwoven having received the fusible.

For the application, the complex according to the invention is placed in such a way that the grid forms the lower face and the nonwoven the upper face.

If we use the option of making basic (see description below) at least one element of the complex reinforcement, we interpose this operation in the above process, or during the manufacture of the element . For example, to impregnate the nonwoven with a basic agent, it is possible either to carry out the impregnation separately, or to carry out the impregnation during the manufacture of the complex, before the deposition of the fusible, or even at the time of application to the site.

When the top layer of asphalt is applied, hot

(approximately at 160 ° C.), the grid / nonwoven assembly traps an air film which will act as a thermal shield against the cold temperature of the lower support, and will therefore optimize the melting of the EVA by the heat provided by the deposition of the upper asphalt layer.

The nonwoven will preferably be a fine hydrophobic nonwoven, of the polyester or polypropylene type, or glass nonwoven, in particular at about 20 - 50 g / m ² , or even up to 80 g / m ² . One can in particular use a polypropylene with 25 g / m ² chemically bonded ("chemical bond"). By way of comparison, the nonwovens of the prior art are used at around 120 g / m ² .

This nonwoven must degrade mechanically by puncturing by the aggregates contained in the mix, due to gravity and compaction (see Fig. 3). The fine nonwoven degrades in the event of an open grid; in the case of a tight grid, the nonwoven will be thicker and will be less degraded, or will not be degraded. By "open grid" is meant a grid with a wide mesh with respect to the granules contained in the upper asphalt layer.

The grid will preferably be a grid of glass filaments:

^* open by more than 70% in the event of asphalt reinforcement,

tight in case of reinforcement of the bituminous membrane based on emulsion.

The mesh of the products will preferably be 5 x 5 mm;

10 x 10 mm; 30 x 30 mm; 40 x 26 mm; 50 x 50 mm. A 40 x 26 mesh will be preferred.

The invention also relates to a method and an armature making it possible to break the bitumen emulsion more quickly.

According to another aspect of the invention, one or more of the elements constituting the complex are brought to a basic pH, that is to say that the grid and / or the nonwoven and / or the fusible is carried, at basic pH.

To do this, one can incorporate a basic agent in the mass of the grid, or in the mass of the fusible, or in the mass of the nonwoven.

Preferably, the structure according to the invention will be impregnated, either the grid / nonwoven assembly, or, very preferably, the nonwoven deposited on the grid, with a basic agent.

The basic agent will be any agent or mixture of agents capable of giving the structure a basic character sufficient to significantly accelerate the "breakage" of the emulsion, such as for example the soda ash. The emulsion can thus be "broken" almost instantly or instantly. This additional measure saves the site a lot of time during implementation, in particular by not making the teams wait unnecessarily.

Any basic agent or any mixture of basic agents capable of, or adapted to, meet the criterion of breakage of the emulsion may be used. Such products will be within the reach of the skilled person.

On contact with the bitumen layer deposited on the support, the basic agent acts on the emulsion and effectively, simply and practically causes this emulsion to break or break. Without wishing to be bound by any theory, the Applicant considers that the basic agent deactivates the acid sites of the surfactants used to maintain the stability of the emulsion.

The invention will be better understood on reading the description which follows, and with reference to the appended drawings, in which:

- Figure 1 schematically shows a sectional view of a representative road structure;

- Figure 2 schematically shows a sectional view of a road structure comprising the frame according to the invention. This figure is intended to represent the order in which the various elements are positioned. The final structure obtained is shown in Figure 3.

FIG. 3 schematically represents in section the final structure obtained when the elements of the invention are available in accordance with FIG. 2.

In the figures, the references have the same meanings, which are as follows:

ground base layer consisting of flattened compacted pebbles

lower bituminous emulsion, highly dosed with residual bitumen (approx. 1 kg / m ² )

4 "serious bitumen" (coated with larger particle size)

5 wearing course

6 bitumen emulsion (0.5 mm) (bonding layer)

7 reinforcement, which can be either a nonwoven which reinforces the bituminous membrane, or a grid, or a grid-nonwoven complex, and the like

8 asphalt layer (6 to 15 cm in one or more layers separated by a thin bonding layer)

20 non woven

21 iron-on

22 grid (with opening mesh "m")

23 asphalt stones

FIG. 1 describes a conventional road structure when a reinforcement is incorporated. On the ground 1 and a layer of leveled pebbles 2, a thin bonding layer (emulsion) 3 is deposited, then a coating layer 4 which forms the "serious bitumen". This layer will receive the wearing course 5 which consists, in its simplest form, of a thin layer of emulsion 6 on which the reinforcement 7 is placed, after which the final coated layer 8 is deposited.

One or more layers of asphalt 8 superimposed on the grid are applied, depending on the type of road structure. The the highest asphalt layer is called the wearing course. The asphalt layers are then bonded together by a thin bonding layer of the layer 6 type. The invention also applies to such variants.

FIG. 2 represents the order of arrangement of the elements according to the invention. On the serious bitumen 4, the bonding emulsion 6 is deposited. This emulsion, in accordance with an important advantage of the invention, will preferably be dosed at only 200 - 300 g of residual bitumen per m ² . The complex 7 according to the invention is then deposited, for example manufactured as described above. This complex consists of the grid 22 and the fine nonwoven 20, the latter carrying on its underside the fusible 21. The coated layer 8 is then deposited (or the first layer if there must be several), which contains pebbles 23. The temperature means that the water of the emulsion 6 can escape. This will be all the easier if the emulsion is broken quickly by a basic agent incorporated, as described above, for example in the nonwoven. The heat of the layer 8 also brings the fusible 21 to its melting point. If this point is relatively high, like that of EVA for example, which can have a melting point of around 80 ° C., the film of air trapped between the serious bitumen and the nonwoven will prevent the fusible and the lower surface of the mix to be cooled by the "cold" layer (4, 6).

FIG. 3 represents the final state of the road structure, after the sequence shown in FIG. 2. It can be seen that the stones 23 of the asphalt 8 have penetrated between the strands of the grid 22, through the fine nonwoven 20 , and if necessary by tearing it, possibly until it comes into contact with the bonding layer 6 which has itself been at least softened by the heat and therefore has been at least partially integrated into the assembly. It has not been possible in practice to represent the fusible 21 which has melted and has been integrated into the assembly at the level, substantially, of the nonwoven. The whole forms a structure of which all the layers are perfectly integral.

The invention also relates to a method of reinforcing road structures, characterized in that it is deposited on the layer bitumen emulsion covering the serious bitumen, a reinforcement as described above, then a coating layer, and also, as a particular variant of implementation, the method of reinforcing road structures described above, characterized in that one or more upper layers of asphalt are deposited, each layer being linked by an intermediate layer of bitumen emulsion.

The invention relates in particular, according to a preferred embodiment, the method of reinforcing road structures which consists in unwinding the complex prefabricated reinforcement according to the invention on the emulsion layer covering the serious bitumen.

The various elements of the complex framework can also be unrolled separately on the site. One can in particular unroll the grid then the nonwoven carrying the fusible "sprinkled" or deposited in perforated film on its underside. The nonwoven may have been previously impregnated with a basic agent, or may contain a basic agent in the mass. It is also possible to incorporate the basic agent into the fusible deposited on the nonwoven. Finally, a basic agent can be deposited on the grid or on the nonwoven as and when it is unrolled.

The invention also relates to a method for reinforcing road structures, characterized in that at least one layer of asphalt is deposited on the reinforcement, or characterized in that several layers of asphalt are deposited on the reinforcement, each layer being separated by a bonding layer of bitumen emulsion.

The invention also relates to a method for reinforcing road structures, characterized in that a 200 to 300 g / m ² emulsion of residual bitumen is used as the lower bonding layer of bitumen emulsion.

In general, the invention also relates to a method of reinforcing road structures according to which a nonwoven is used (possibly alone on certain sites) or any type of a complex frame of the grid type, possibly comprising a nonwoven or a structure. analogous, characterized in that said nonwoven is worn, or one or more of the elements constituting the complex of the type grid at a basic pH capable of accelerating the breakage or rupture of the lower bitumen emulsion. In this general process, all the applicable variants of the invention may be implemented, in whole or in part, by adapting them to the nonwoven or to the type of complex reinforcement used.

Those skilled in the art will be able to modify or adapt the invention according to the usual criteria of the profession.

Claims

1 - Complex reinforcement of the type comprising a grid, for the reinforcement of road structures, characterized in that it comprises:

a grid

a fine nonwoven deposited on the grid

2. - Reinforcement according to claim 1, characterized in that the nonwoven is only partially clogged with the fusible product.

3. - Reinforcement of the grid type for the reinforcement of road structures, according to claim 1 or 2, characterized in that one or more of the elements constituting the complex are brought to a basic pH.

4. - Reinforcement of the grid type for the reinforcement of road structures, according to claim 3, characterized in that the grid and / or the nonwoven and / or the fusible, are brought to a basic pH.

5. - Reinforcement of the grid type for the reinforcement of road structures, according to claim 3 or 4, characterized in that a basic agent is incorporated in the mass of the grid, or in the mass of the fusible, or in the mass of the no woven.

6. - Reinforcement of the grid type for the reinforcement of road structures, according to any one of claims 3 to 5, characterized in that the structure according to the invention is impregnated, either the grid / nonwoven assembly, or the nonwoven deposited on the grid, by a basic agent.

7. - Reinforcement of the grid type for the reinforcement of road structures, according to any one of claims 3 to 6, characterized in that the basic agent will be chosen from any agent or mixture of agents capable of imparting to the complex structure a basic character sufficient to significantly accelerate the "breakage" of the emulsion, such as for example sodium carbonate.

8. - Reinforcement of the grid type for the reinforcement of road structures, according to any one of claims 1 to 7, characterized in that at least one of the components of the complex, and in particular is the grid / nonwoven assembly , either the nonwoven deposited on the grid, or the grid, or the fusible, is impregnated with a basic agent.

9. - Reinforcement of the grid type for the reinforcement of road structures, according to any one of claims 1 to 8, characterized in that the nonwoven is deposited on the upper face of the grid and in that the fusible is interposed between the grid and the nonwoven, in "dusting" or in perforated film, to partially close the mesh of the nonwoven.

10. - Reinforcement of the grid type for reinforcing road structures, according to any one of claims 1 to 9, characterized in that the fusible product is an EVA (ethylene / vinyl acetate) copolymer.

1 1. - Reinforcement of the grid type for reinforcing road structures, according to any one of claims 1 to 10, characterized in that the nonwoven is a fine nonwoven, of the polyester or polypropylene type, or glass nonwoven, at approximately 20 - 80 g / m ² , preferably 20 - 50 and particularly 20 - 30 g / m ² , and in particular a polypropylene at 25 g / m ² chemically bonded ("chemical bond").

12. - Reinforcement of the grid type for the reinforcement of road structures, according to any one of claims 1 to 1 1, characterized in that the grid is a grid of 5 x 5 mm mesh glass filaments; 10 x 10 mm; 30 x 30 mm; 40 x 26 mm; 50 x 50 mm, preferably 40 x 26 mm.

13. - A method of reinforcing road structures according to which a complex reinforcement of the grid type is used, characterized in that a reinforcement according to any one of claims 1 is deposited on the bitumen emulsion layer covering the bituminous concrete. at 12.

14. - A method of reinforcing road structures according to claim 13, characterized in that at least one layer of asphalt is deposited on the reinforcement.

15. - A method of reinforcing road structures according to claim 13 or 14, characterized in that several layers of asphalt are deposited on the reinforcement, each layer being separated by a bonding layer of bitumen emulsion.

16. - A method of reinforcing road structures according to any one of claims 13 to 15, characterized in that one uses as the lower bonding layer of bitumen emulsion an emulsion with 200 - 300 g / m ² of bitumen residual.

17. - A method of reinforcing road structures according to any one of claims 13 to 16, characterized in that it consists in unwinding the complex prefabricated reinforcement according to any one of claims 1 to 12 on the emulsion layer covering bituminous concrete.

18. - A method of reinforcing road structures according to any one of claims 13 to 16, characterized in that it consists in unrolling separately on the site the various elements of the complex reinforcement of the prefabricated complex reinforcement according to one any of claims 1 to 12, on the emulsion layer covering the bituminous concrete.

19. - A method of reinforcing road structures according to claim 18, characterized in that the grid is unwound and then the nonwoven carrying the fusible "sprinkled" or deposited in perforated film on its underside, the nonwoven having or not been impregnated beforehand with a basic agent, or possibly comprising a basic agent in the mass, or the basic agent being incorporated into the fusible deposited on the nonwoven, or the basic agent being deposited on the grid or on the nonwoven as and as we unroll it.