EP0603369A1

EP0603369A1 - Advanced rising crack prevention system between the structural and wearing courses of a roadway, and method for producing same

Info

Publication number: EP0603369A1
Application number: EP93914814A
Authority: EP
Inventors: Pierre Chaverot; Emile Lopez
Original assignee: Elf Antar France
Current assignee: Elf Antar France
Priority date: 1992-07-07
Filing date: 1993-07-05
Publication date: 1994-06-29
Anticipated expiration: 2013-07-05
Also published as: JPH07501371A; ATE165130T1; ES2112746A1; WO1994001623A1; CA2117087A1; FI941042A; DE69317989D1; EP0603369B1; ES2112746B1; FR2693490A1; FR2693490B1; BR9305576A; US5445473A; FI941042A0

Abstract

PCT No. PCT/FR93/00690 Sec. 371 Date Apr. 25, 1994 Sec. 102(e) Date Apr. 25, 1994 PCT Filed Jul. 5, 1993 PCT Pub. No. WO94/01623 PCT Pub. Date Jan. 20, 1994.A rising crack prevention system between the structural and wearing courses of a roadway is provided which includes a geotextile layer impregnated with a first asphalt binder, and further includes a layer of roadstones coated with a second asphalt binder adjacent to the geotextile layer impregnated with the first asphalt binder. The unique double-layer construction of the rising crack prevention system is efficient in preventing or at least greatly slowing down the spread of cracks from the structural course to the wearing course of the road.

Description

IMPROVED ANTI-RISE OF CRACKS SYSTEM INTERCAL BETWEEN THE STRUCTURE LAYER AND THE ROAD LAYER OF A PAVEMENT AND METHOD FOR THE PRODUCTION OF SUCH A SYSTEM

The invention relates to an improved system for preventing cracks from rising between the structural layer and the wearing course of a roadway. It also relates to a method for producing such a system.

Road or airport pavements are generally formed of several layers, namely an upper layer, called a wearing course, based on a material of the surface-coated type or even of the bituminous concrete type and one or more lower layers forming the structural layer. pavement, based on materials treated with hydraulic binders such as cements, blast furnace slag, pozzolan, fly ash, bituminous binders.

For structures with hydraulic binders, the various mechanical and thermal stresses of a static nature, for example setting shrinkage and thermal shrinkage of materials, or of a dynamic nature, namely constraints related to traffic, to which the roadways are subjected, cause cracking of the structural layer, the cracks generated are transmitted more or less quickly to the wearing course and then appear on the surface of the latter. The presence of cracks on the surface of the road allows water to enter the body of said road, which causes rapid and significant degradation of the latter.

To prevent or at least delay the appearance of cracks in the wearing course of a roadway, the structural layer of which is subject to cracking, various solutions have been proposed, such as: creation of an interface consisting of a membrane in bitumen / rubber poured on the layer of structure to decouple the movements of the latter and those of the wearing course which overcomes it,

- tensile reinforcement of the bituminous concrete surface layers by polyester grids having sufficient mechanical characteristics, or

- depositing a polyester nonwoven on the cracked structure layer, then covering the nonwoven with a layer of about five centimeters of bituminous concrete which constitutes the wearing course.

Such solutions have not led to satisfactory results, the cracks reappearing more or less quickly on the surface.

A more efficient solution, proposed in the citation FR-A-2592411, consists in interposing, between the structural layer and the wearing course, an interface in non-woven geotextile impregnated with a bituminous binder consisting of a modified bitumen, for example , by a copolymer of styrene and a conjugated diene such as butadiene.

We have now found that it is possible to improve the performance of anti-rising systems of cracks of the type described in FR-A-2592411, by adding a layer of aggregates coated with a bituminous binder to the geotextile layer. itself impregnated with a bituminous binder.

The crack prevention system according to the invention, which is interposed between the structural layer and the wearing layer of a roadway, is of the type comprising a layer of a geotextile impregnated with a first bituminous binder, and it is characterized in that it also includes a layer of aggregates coated with a second bituminous binder, which is attached to the geotextile layer impregnated with a first bituminous binder. According to a first embodiment, the anti-rising crack system is arranged so between the structural layer and the wearing course of the roadway that the geotextile layer impregnated with the first bituminous binder rests on the structural layer of the road, while the layer of aggregates coated with the second bituminous binder is coated with the wearing course. According to a second embodiment, the anti-rising crack system is arranged so between the structural layer and the wearing course of the roadway that the layer of aggregates coated with the second bituminous binder rests on the structural layer of the pavement, while the geotextile layer impregnated with the first bituminous binder is coated with the wearing course.

The layer of aggregates coated with the second bituminous binder can advantageously be a layer of sand coated with said binder. One can also constitute the layer of aggregates coated with the second bituminous binder by a layer of a cold-cast mix or even by a layer of draining mix.

By geotextile is meant according to the invention any textile web of tight texture, which is produced from natural or synthetic yarns or fibers and which is used in the usual way in road construction and land stabilization operations. Advantageously, the geotextile used according to the invention consists of a nonwoven web formed from continuous filaments based on a polymer such as polyester, isotactic polypropylene, polyamide, polyacrylonitrile, cellulose acetate, polyvinyl chloride, polyvinylidene chloride. Especially suitable for a geotextile consisting of a tightly woven nonwoven web formed from continuous filaments based on isotactic polypropylene, or else a polyester, especially polyethylene terephthalate glycol such as polyethylene terephthalate, or else a polyamide, in particular polycaproamide or polyhexamethylene adipamide. The nonwoven web formed from continuous filaments based on a polymer may in particular be the web described in one or other of the citations FR-A-1601049, FR-A-2108145 and FR-A- 2592411, said citations indicating the general method of producing such a web.

The surface mass of the textile sheet constituting the geotextile can vary quite widely and is advantageously between 50 and 500 g / m2. For example, when the textile web has the structure of the web described in the quote FR-A-2592411, the surface mass of said textile web is preferably between 100 and 300 g / m2.

The first bituminous binder, which impregnates the geotextile to form the geotextile layer impregnated with the anti-crack recovery system, is advantageously used in an amount between 200 g and 1500 g and preferably between 300 g and 1000 g per square meter of sheet. geotextile. The second bituminous binder associated with the aggregates, to form the layer of aggregates coated with the anti-crack-lifting system, is used in an amount advantageously between 3 and 20% and more particularly between 4 and 12% of the weight of the aggregates. In the variant "sand coated with the second bituminous binder", the aggregate component can be chosen from the various sands which are used on road construction sites and whose passing through a 6 mm sieve is greater than 80% and preferably equal to 100 %. In the variant "cold-cast mix", the aggregate component, chosen from sands that are used on road construction sites and whose 6 mm sieve pass-through is greater than 80%, is coated with the second bituminous binder, used as an aqueous emulsion, after having previously been brought into contact with a surfactant solution and optionally with an amount of cement less than 3% of the weight of the sand forming the aggregate component.

In the "coated asphalt" variant, the aggregate component, chosen from gravel which is used on road construction sites and whose 20 mm sieve is greater than 90%, is hot-coated with the second bituminous binder so as to provide, after compaction, a vacuum content in the mix between 15% and 35% and preferably between 20% and 30%.

The first bituminous binder, which permeates the geotextile, as well as the second bituminous binder, which coats the aggregates, can be of identical or different natures and are chosen from bitumens and bitumens modified by polymers, which have a dynamic viscosity at 100 ° C between 0.4 Pa.s and 25 Pa.s and preferably between 0.7 Pa.s and 20 Pa.s. The first and second bituminous binders can be chosen in particular from bitumens modified by copolymers of styrene and a conjugated diene and very especially from bitumens modified by block copolymers of styrene and a conjugated diene such as butadiene, isoprene , carboxylated butadiene, the preparation of which is described in the citations FR-A-2376188, FR-A-2429241, FR-A-2528439 and FR-A-2636340.

To impregnate the geotextile or coat the granules with the chosen bituminous binder, the latter can be used either in the molten state or in the form of an aqueous emulsion, for example the emulsion described in one or the other of the citations FR-A-2517317, FR-A-2577545 and FR-A-2577546.

To produce an anti-crack recovery system according to the invention, interposed between the structural layer and the wearing layer of a roadway, said system comprising a layer of a geotextile impregnated with a first bituminous binder and attached to a layer of aggregates coated with a second bituminous binder, one of the layers of the anti-rising crack system is applied to the pavement structure layer, then the layer thus formed is coated with the other layer of the anti-crack recovery system and the wearing course is applied to the assembly thus formed.

According to a first embodiment, the geotextile layer impregnated with the first bituminous binder is first applied to the pavement structure layer, then the geotextile layer is coated with the layer of coated aggregates of the second bituminous binder and on this last layer, the road surface is applied.

According to a second embodiment, the layer of aggregates coated with the second bituminous binder is first applied to the structural layer of the roadway, then the said layer of aggregates coated with the layer of geotextile impregnated with first bituminous binder and on this last layer the road surface is applied. The wearing course of the road, which rests on the anti-rising crack system, can be of any type known in the art, the binder used for this wearing course being a pure bitumen or a bitumen modified by a polymer. and in particular by a copolymer of styrene and of a conjugated diene such as butadiene, isoprene or carboxylated butadiene.

When the structural layer of the pavement is cracked, it is useful to plug the widest cracks, for example cracks wider than 2 mm, using a bridging agent consisting of bituminous mastic before apply, on said structural layer, the first layer, namely impregnated geotextile or coated aggregates, as the case may be, with the anti-crack rise system. The layer of aggregates coated with the second bituminous binder which constitutes one of the two layers of the anti-rising crack system according to the invention has a thickness which may be between 1 cm and 6 cm.

The invention is illustrated by the following examples given without limitation. EXAMPLES 1 TO 3:

In these examples, we study the propagation of cracks in test pieces simulating a pavement structure with or without an anti-rising crack system.

The test pieces used each consisted of a rectangular multilayer plate, said plate having a length of 560mm and a width of 110mm and comprising a pre-cracked support layer along its transverse axis simulating the cracked structure layer of a roadway and an apparent layer simulating the wearing course of the roadway, the latter layer resting directly on the pre-cracked support layer or being separated from this support layer by a anti-crack recovery system.

By using said test pieces, tests were carried out to determine the rate of ascent of the crack of the support layer in the layer of the test piece simulating the wearing course.

These tests were carried out on a withdrawal-bending test machine comprising a fixed plane support element and a plane support element movable in translation, together defining a horizontal support plane. The test piece was mounted on the test machine so that one of the halves of the free face of the transverse pre-cracked support layer of the test piece was glued to one of the flat support elements and that the other of said halves was glued to the other of said planar support elements.

Each test piece mounted on the testing machine was subjected, under constant temperature conditions (operation at a temperature of 5 ° C), simultaneously to two types of stress, namely - slow continuous longitudinal traction, with a speed of 5 μm per minute, simulating thermal shrinkage, and

- a cyclic vertical bending, at the frequency of 1Hz, simulating the traffic. The progress of the crack in the layer of the test specimen simulating the wearing course was followed by means of a network of electrically conductive wires glued at different heights to the edge of said layer in the area of this edge where the crack so that the rise of the crack in the layer causes a successive cut of these wires, the position of the cut wires being recorded as a function of the stressing time of the test piece. On the curve thus obtained, representative of the propagation of the crack as a function of time, the time tR2 was determined at the end of which the crack had risen by 2 cm in the wearing course. The test pieces used during the tests had the following structures:

EXAMPLE 1: two-layer test pieces not comprising an anti-rising crack system, said test pieces being formed of a prefissured support layer 15 mm thick directly surmounted by a wearing layer 50 mm thick.

EXAMPLE 2: test pieces comprising a pre-cracked support layer 15 mm thick and a wearing layer 30 mm thick between which was interposed a witness system anti-crack recovery consisting of a geotextile sheet impregnated with a bituminous binder of bitumen / polymer type.

EXAMPLE 3 test pieces comprising a pre-cracked support layer 15 mm thick and a wearing layer 30 mm thick between which was interposed an anti-crack recovery system according to the invention, said system being formed of a layer consisting of a geotextile sheet impregnated with a bituminous binder of the bitumen / polymer type resting on the support layer and surmounted by a layer of 20 mm thick of sand coated with a bitumen / polymer binder, this layer of coated sand being surmounted by the wearing course.

The transverse pre-cracked support layer of the various test pieces was made from the same bituminous concrete based on sand, bitumen and sulfur.

The wearing course of the various test pieces consisted of a discontinuous 0/10 bituminous concrete formed from 6 parts by weight of a bitumen / polymer composition vulcanized with sulfur and from 100 parts by weight of a mixture consisting, by weight, of 60%. gravel 6 / 10mm, 10% 0 / 4mm sand, 27.5% 0 / 2mm sand and 2.5% filler fines (80% of said fines passing the 80μm sieve and 100% passing the 315μm). The bitumen / polymer composition used for producing the wearing course of the test pieces was prepared as follows. 100 parts by weight of a 180/220 bitumen with a penetration equal to 200 were mixed at 170 ° C. with stirring, with 3 parts by weight of a butadiene / styrene block copolymer having an average viscosimetric molecular weight equal to 75,000 and a styrene content by weight equal to 25%, then after 3.5 hours of mixing, 0.1 part by weight of sulfur was added to the mass obtained and stirring was continued at the temperature of 170 ° C. for another 30 minutes.

The bitumen / polymer composition obtained had a dynamic viscosity at 100 ° C equal to 8.5 Pa.s.

The geotextile sheet impregnated with bituminous bitumen / polymer binder, used in the test pieces of Examples 2 and 3, consisted of a sheet of a nonwoven of isotactic polypropylene yarns having a grammage of 170 g / m ² impregnated with 900 g / m ² d 'a bitumen / polymer binder having a dynamic viscosity at 100 "C equal to 1 Pa.s, said binder being applied to the web in the form of an aqueous emulsion.

This bitumen / polymer binder was prepared as follows. A stock solution was first formed by incorporating, at 100 ° C. and with stirring, 2.4 parts by weight of orthorhombic crystallized sulfur and 62 parts by weight of the styrene / butadiene block copolymer defined above at 230 parts by weight of an oil cut of naphtheno-paraffinic character having an initial point and an end point of ASTM distillation (standard ASTM D8 667) equal respectively to 162 ° C and 233 ° C, said incorporation being carried out in 1 hour. The mother solution thus obtained was then incorporated into 1950 parts by weight of a bitumen with a penetration equal to 82, maintained at 170 ° C with stirring, after which the mixture thus produced was still kept under stirring at 170 ° C for 30 minutes.

The bitumen / fluidized polymer binder (dynamic viscosity at 100 ° C equal to 1 Pa.s) thus obtained was then put into an aqueous emulsion as indicated in Example 3 of the citation FR-A-2577546 to produce the bitumen / polymer binder emulsion used to impregnate the geotextile sheet.

The layer of sand coated with bitumen / polymer binder present in the test pieces of Example 3 was formed by 9 parts by weight of bitumen / polymer binder consisting of the same bitumen / polymer composition as that used in the constitution of the wearing course. and 100 parts by weight of a mixture made up, by weight, of 44% 2/6 mm gravel, 53% 0 / 2mm sand and 3% of filler fines of the same kind as those used to produce the layer of rolling.

The results of the control tests and according to the invention are collated in the table below.

BOARD

The comparison of the results recorded in the table clearly shows the greatly improved efficiency of an anti-crack recovery system according to the invention (example 3) compared to a anti-crack recovery system according to the state of the art. (example 2).

Claims

CLAIMS - Anti-rising crack system, interposed between the structural layer and the wearing course of a roadway, of the type comprising a layer of a geotextile impregnated with a first bituminous binder, characterized in that it also includes a layer of aggregates coated with a second bituminous binder, which is attached to the geotextile layer impregnated with the first bituminous binder.

- System according to claim 1, characterized in that it is arranged so between the structural layer and the wearing course of the road that the geotextile layer impregnated with the first bituminous binder rests on the structural layer of the road , while the layer of aggregates coated with the second bituminous binder is coated with the wearing course.

3 - System according to claim 1, characterized in that it is arranged so between the structural layer and the wearing course of the road that the layer of aggregates coated with the second bituminous binder rests on the structural layer of the pavement, while the geotextile layer impregnated with the first bituminous binder is coated with the wearing course.

4 - System according to one of claims 1 to 3, characterized in that the geotextile consists of a textile sheet of tight texture having a surface mass of between 50 and 500 g / m2.

5 - System according to claim 4, characterized in that the textile web consists of a nonwoven formed of continuous filaments based on a polymer. 6 - System according to claim 5, characterized in that the filaments forming the nonwoven web are based on a polyester, for example alkylene glycol terephthalate such as polyethylene terephthalate glycol, or a polyamide, for example polycaproamide or polyhexamethylene adipamide, or isotactic polypropylene.

7 - System according to one of claims 1 to 6, characterized in that the first bituminous binder which permeates the geotextile is used in an amount between 200 g and 1500 g and preferably between 300 g and 1000 g per m2 of geotextile sheet .

8 - System according to one of claims 1 to 7, characterized in that the second bituminous binder associated with the aggregates to form the coated layer is used in an amount between 3 and 20% and more particularly between 4 and 12% of the weight of aggregates

9 - System according to one of claims 1 to 8, characterized in that the layer of aggregates coated with the second bituminous binder consists of a layer of sand coated with said binder.

10- System according to claim 9, characterized in that the sand used to form the layer of coated sand is chosen from sands which are used on road construction sites and whose passing through a 6 mm sieve is greater than 80% and of preferably equal to 100%.

11- System according to one of claims 1 to 8, characterized in that the layer of aggregates coated with the second bituminous binder consists of a cold-cast mix. 2- The system as claimed in claim 11, characterized in that the cold-cast mix consists of an aggregate component, chosen from the sands which are used on road construction sites and whose passing through a 6 mm sieve is greater than 80%, coated with the second bituminous binder, used in aqueous emulsion, after having previously been brought into contact with a surfactant solution and optionally with an amount of cement less than 3% of the weight of the sand forming the aggregate component.

3- System according to one of claims 1 to 8, characterized in that the layer of aggregates coated with the second bituminous binder consists of a draining asphalt.

4- The system as claimed in claim 13, characterized in that the draining asphalt consists of an aggregate component, chosen from gravel which is used on road construction sites and whose passing through a 20 mm sieve is greater than 90%, coated with hot by the second. bituminous binder so as to provide, after compaction, a void content in the mix between 15% and 35% and preferably between 20% and 30%.

15- System according to one of claims 1 to 14, characterized in that the first bituminous binder, which permeates the geotextile, and the second bituminous binder which coats the aggregates, are of different or identical natures and are chosen from pure bitumens and bitumens modified by polymers, which have a dynamic viscosity at 100 ° C of between 0.4 Pa.s and 25 Pa.s and preferably between 0.7 Pa.s and 20 Pa.s.

16- System according to claim 15, characterized in that the first and the second bituminous binders are chosen from bitumens modified by copolymers of styrene and a conjugated diene and in particular from bitumens modified by block copolymers of styrene and a conjugated diene such as butadiene, isoprene or carboxylated butadiene.

17- System according to one of claims 1 to 16, characterized in that the bituminous binder is used in the molten state or in the form of an aqueous emulsion to effect the impregnation of the geotextile and the coating of the aggregates.

18- Method for producing an anti-rising crack system, sandwiched between the structural layer and the wearing course of a roadway, said system comprising a layer of a geotextile impregnated with a first bituminous binder and attached to a layer of aggregates coated with a second bituminous binder, said process being characterized in that one of the layers of the anti-crack recovery system is applied to the structure layer of the roadway, and then the layer is coated formed using the other layer of the anti-rising crack system and the wearing course is applied to the assembly thus formed.

19- The method of claim 18, characterized in that one firstly applies the geotextile layer impregnated with the first bituminous binder on the pavement structure layer, then coating said geotextile layer with the layer of aggregates coated with the second bituminous binder and on this last layer, the road surface is applied.

20- The method of claim 18, characterized in that firstly applies the layer of aggregates coated with the second bituminous binder on the structural layer of the road, then coating said layer of aggregates coated with the layer of geotextile impregnated with the first bituminous binder and on this last layer, the road surface is applied. 21- Method according to one of claims 18 to 20, characterized in that the geotextile consists of a textile sheet of tight texture having a surface mass between 50 and 500g / m ² .

22- The method of claim 21, characterized in that the textile web consists of a nonwoven formed of continuous filaments based on a polymer.

23- The method of claim 22, characterized in that the filaments forming the nonwoven web are based on a polyester, for example polyethylene terephthalate such as polyethylene terephthalate, or a polyamide, for example polycaproamide or polyhexamethyleneadipamide, or isotactic polypropylene.

24- Method according to one of claims 18 to 23, characterized in that the amount of the first bituminous binder which permeates the geotextile, is between 200g and 1500g and preferably between 300g and 1000g per m ² of geotextile sheet.

25- Method according to one of claims 18 to 24, characterized in that the amount of second bituminous binder which coats the aggregates is between 3 and 20% and more particularly between 4 and 12% of the weight of said aggregates.

26- Method according to one of claims 18 to 25, characterized in that the layer of aggregates coated with the second bituminous binder consists of a layer of sand coated with said binder or in a cold poured mix or in a drained mix.

27- Method according to one of claims 18 to 26, characterized in that the first and the second bituminous binders are chosen from pure bitumens and bitumens modified by polymers, which have a dynamic viscosity at 100 ° C of between 0.4 Pa.s and 25 Pa.s and preferably between 0.7 Pa.s and 20 Pa.s, said bituminous binders being more particularly bitumens modified with copolymers of styrene and of a conjugated diene, said copolymers being more especially block copolymers of styrene and of a conjugated diene such as butadiene, isoprene or carboxylated butadiene.

- Method according to one of claims 18 to 27, characterized in that the bituminous binder is used in the molten state or in the form of an aqueous emulsion to effect the impregnation of the geotextile and the coating of the aggregates.

- Method according to one of claims 18 to 28, characterized in that the wearing course contains a binder consisting of a pure bitumen or a bitumen modified by a polymer and in particular by a block copolymer of styrene and a conjugated diene such as butadiene, isoprene or carboxylated butadiene.

- Method according to one of claims 18 to 29, characterized in that the structural layer of the roadway being cracked, the widest cracks are plugged, in particular cracks of width greater than 2mm, using a putty bituminous before applying, on said structure layer, the impregnated geotextile layer or the layer of aggregates coated with the anti-crack recovery system.