METHOD FOR THE HIGH SPEED INDENTATION OF A RECYCLABLE HEAT EXCHANGER IN A LAND-BASED INFRASTRUCTURE

Abstract

The present invention relates to a method for manufacturing a road surfacing comprising on the surface the pipes of a heat exchanger device, characterised in that it comprises the following steps: a) spreading at a temperature below 160 C. asphalt mix, comprising a granular fraction, a hydrocarbon-based binder, said asphalt mix being workable, having a workability, measured with a Nynas workability meter at the working temperature of the asphalt mix, of less than 400N, then b) depositing the pipes, said pipes having a crushing strength greater than 3000 N per linear metre of pipe at 100 C., a thermal expansion less than 200.10.sup.6 K.sup.1 at 20 C. in such a way as to enable their indentation even in the absence of cooling means or pressure application means, then c) indenting the deposited pipes into said integration layer by compacting said asphalt mix during the workability period of said asphalt mix, to form an integration layer comprising the pipes of a heat exchanger device, then d) applying a surface layer there above for the road surface, in particular a surface course.

The present invention also relates to a method for recycling a road surface.

Claims

1.-19. (canceled)

20. Method for manufacturing a road surfacing comprising on the surface the pipes of a heat exchanger device, comprising the following steps: a) spreading at a temperature below 160 C. asphalt mix, comprising a granular fraction, a hydrocarbon-based binder, to form an integration layer, said asphalt mix being workable, having a workability, measured according to the 98-258-1 Standard of 2013, with a Nynas workability meter at the working temperature of the asphalt mix, of less than 400 N. b) depositing the pipes on said integration layer, said pipes being made of polymer, having a crushing strength greater than 3000 N per linear metre of pipe at 100 C., a thermal expansion less than 200.10.sup.6 at 20 C. in such a way as to enable their indentation even in the absence of cooling means or pressure application means. To determine the crushing strength of the pipes, a sample of pipe, of a length between 5 cm and 10 cm, is cut out. This sample is next placed for 2 hours in an oven at a temperature of 100 C. The crushing test is next carried out at the temperature of 100 C. The sample is next positioned, on its generating line, between the two parallel plates of a press, placed in a climatic chamber regulated to 100 C. The press imposes on the sample a displacement of 10 mm/min. The crushing strength value is determined when the diameter of the sample is divided by two compared to the initial diameter of the sample. It is expressed in Newtons per linear metre of pipe using the relationship:
Rt=Ft/Lt with: Rt: crushing strength of the pipe in N/m Ft: force developed to crush the pipe up to a reduction of half of its diameter in N Lt: length of the sample subjected to the test in mm, then c) indenting the deposited pipes into said integration layer by compacting said asphalt mix during the workability period of said asphalt mix, to form an integration layer comprising the pipes of a heat exchanger device, then d) applying a surface layer there above for the road surface, in particular a surface course.

21. Method according to claim 20, wherein a geometry is imposed on the pipes of the heat exchanger device before the deposition step b).

22. Method according to claim 20, wherein during step c) no vibrations are applied.

23. Method according to claim 20, wherein the indentation depth varies from 0.5 d to 1.5 d, advantageously from 0.8 d to 1.2d, with d representing the diameter of the pipes.

24. Method according to claim 20, wherein the working temperature of the asphalt mix is below 130 C., advantageously between 60 C. and 120 C., more advantageously between 90 C. and 120 C.

25. Method according to claim 20, wherein the compactness of the asphalt mix measured by means of a gyratory shear press at 60 gyrations, according to the NF EN 12697-31 Standard of August 2007, is greater than 90%.

26. Method according to claim 20, wherein the workability of the asphalt mix, measured with a Nynas workability meter at the working temperature of the asphalt mix, is less than 300 N, advantageously less than 250 N.

27. Method according to claim 20, wherein the binder comprises a workability additive, having a melting point above 60 C. and below 130 C., in particular the workability additive is a trigylceride of fatty acids, the fatty acid being selected from the group constituted of saturated fatty acids comprising from 12 to 30 carbon atoms, optionally substituted by at least one hydroxyl function or by a C.sub.1-C.sub.4 alkyl radical, in particular the fatty acid is selected from the group constituted of 12-hydroxy-octadecanoic acid, hexadecanoic acid, octadecanoic acid, 9,10-dihydroxy-octadecanoic acid, icosanoic acid, nonadecanoic acid, and mixtures thereof.

28. Method according to claim 20, wherein the elements of the granular fraction of the asphalt mix have dimensions between 0 mm and 10 mm, advantageously between 0 mm and 6 mm.

29. Method according to claim 20, wherein the thermal conductivity, , of the asphalt mix is greater than or equal to 1 W/m.Math.K.

30. Method according to claim 20, wherein the thermal conductivity, , of the asphalt mix is less than 1 W/m.Math.K.

31. Method according to claim 30, wherein the granular fraction of the asphalt mix comprises elements selected from light aggregates of specific gravity less than 1.6 t/m.sup.3.

32. Method according to claim 31, wherein all or part of the light aggregates are non-absorbent light aggregates having a water absorption coefficient less than 15%.

33. Method according to claim 20, wherein the asphalt mix is resistant to rutting, advantageously with a percentage rutting after 30,000 cycles of less than 7.5%, advantageously of less than 5%.

34. Method according to claim 20, wherein the heat exchanger device indented into said integration layer does not comprise any metal element.

35. Method according to claim 20, wherein the thickness of the integration layer varies from d to 10 cm, with d representing the diameter of the pipes.

36. Method according to claim 20, wherein the combined thickness of the layer(s) applied thereafter on said integration layer is less than 30 cm, advantageously less than 10 cm.

37. Method according to claim 20, comprising a step, prior to the spreading of the asphalt mix of the integration layer, of application of a layer of insulating materials.

38. Method for recycling a road surface, comprising a heat exchanger device on the surface, as defined in claim 20, the heat exchanger device indented into said integration layer not comprising any metal element comprising the following successive steps: i. breaking up and removing bound materials including the integration layer comprising the heat exchanger device; ii. recycling the elements recovered at the preceding step, without operation of sorting or separating the elements of the heat exchanger device.

Description

DETAILED DESCRIPTION OF THE METHOD

[0160] The method according to the invention is characterised in that the pipes of a heat exchanger device are integrated in a layer of asphalt mix, designated integration layer, by indentation. This integration layer could support all traffic, including heavy traffic.

[0161] The integration layer is next recovered from at least one road surface layer: [0162] i. adapted to traffic, from light traffic to heavy traffic as a function of the compositions of the layers of the roadway [0163] ii. that is going to capture solar energy (in energy recovery mode) or which will be to heat up (in energy restitution mode)

[0164] The road could be of large surface area, which would provide a heat exchanger of large dimensions.

[0165] To optimise energy efficiency, the integration layer is close to the surface. In particular, the combined thickness of the layer(s) applied thereafter on said integration layer is less than 30 cm, advantageously less than 10 cm. It may for example vary from 2 cm to 30 cm, advantageously from 6 cm to 10 cm.

[0166] The road surface layer could comprise a multilayer constituted of at least one binder course and one surface course.

[0167] In an alternative, the binder course has a thickness ranging from 4 cm to 14 cm, advantageously from 4 cm to 7 cm.

[0168] In an alternative, the surface course has a thickness ranging from 2 cm to 10 cm, advantageously from 5 cm to 7 cm.

[0169] For all the thicknesses, unless indicated otherwise, it is the thickness after compacting.

[0170] The method according to the invention makes it possible to integrate the pipes of the heat exchanger device in an integration layer during the laying of the roadway integrating said integration layer.

[0171] The pipes are indented into the integration layer during the implementation period of the asphalt mix of the integration layer, before the end of compacting. This implementation period is defined by the workability of the asphalt mix.

[0172] A successful indentation depends both on the workability of the asphalt mix and the crushing strength of the pipe. The greater the crushing strength of the pipe, the wider the tolerance threshold on the workability of the asphalt mixes. The more workable the asphalt mix, the wider the tolerance threshold on the crushing strength of the pipes.

[0173] However, whatever the workable asphalt mix, the pipe has a crushing strength greater than 3000 N per linear metre of pipe at 100 C.

[0174] However, whatever the pipe, the minimum workability of the asphalt mix, measured with a Nynas workability meter at the working temperature of the asphalt mix, is less than 400 N.

[0175] In one embodiment of the invention, the workability of the asphalt mix is between 300 N and 400 N. Then, the crushing strength of the pipes is greater than 4500 N per linear metre of pipe at 100 C.

[0176] In another embodiment of the invention, the workability of the asphalt mix is less than 300 N. Then, the crushing strength of the pipes is greater than 3000 N per linear metre of pipe at 100 C.

[0177] The indentation depth advantageously varies from 0.5 d to 1.5 d, more advantageously from 0.8 d to 1.2 d, with d representing the diameter of the pipes. To ensure a planeness of the integration layer, it is desirable that not more than half of the diameter of the pipes juts beyond the layer. On the other hand, to ensure good thermal exchanges with the overlying roadway, the pipes have to be as close as possible to the surface.

[0178] A great advantage of the method according to the invention is that compacting may be carried out directly, without requiring additional step(s) of protection of the pipes.

[0179] Moreover, the following steps, of application above the integration layer of the surface layer(s) for road surface may be carried out directly, without requiring additional step(s) of protection of the pipes. Indeed, the integration layer makes it possible not only to maintain on the ground the desired geometry but also to protect the pipes.

[0180] The asphalt mix is spread according to traditional methods, advantageously using a paver. Hot or lukewarm asphalt mix could be used, with a preference for lukewarm asphalt mix.

[0181] In particular, the working temperature of the asphalt mix is below 160 C., advantageously below 140 C., more advantageously below 130 C. In one embodiment, the working temperature of the asphalt mix is between 60 C. and 120 C., advantageously between 90 C. and 120 C.

[0182] The pipes of the device are next deposited and indented by compacting in the asphalt mix during their implementation period. By the method according to the invention, the pipes are not damaged, in particular deformed, by the rollers of the compactor and remain in position, whatever their curvature, and thereby including in the loops or bends. The same is true when pavers, including pavers with caterpillar tracks, next pass over the indented pipes.

[0183] As is the practice, the compacting could be done in several passes.

[0184] Advantageously, no vibration is applied during compacting. Thus, advantageously, during step c) no vibration is applied.

[0185] Conditioning the pipes in the form of rolls or slabs makes it possible to ensure high laying speeds. Advantageously, the laying and indentation speed is greater than 2 m/min, more advantageously from 4 m/min to 10 m/min.

[0186] The laying of the pipes simultaneously with the conception of the integration layer according to the invention, in particular with a compact asphalt mix, makes it possible to ensure optimal contact between the pipes and the asphalt mix and thereby limit the presence of voids around the pipes. Thus, the method according to the invention does not require the use of a filling material and/or adhesive.

[0187] Advantageously, the heat exchanger device integrated in the integration layer does not comprise any metal element. Thus, the materials constituting the device (the pipes, the substrate and optional attachment elements) do not form an obstacle to a recycling, advantageously simultaneously, of the asphalt mix, as has already been described previously.

[0188] The addition of pipes, made of polymer, in the surface layer is not detrimental either to its recycling.

[0189] The integration layer advantageously comprises less than 10%, more advantageously less than 5%, even more advantageously less than 1%, by volume of polymer per m.sup.3 of asphalt mix. Thus, this layer, after planing during reworking of the roadway, may be recycled and re-used without prior treatment.

[0190] The thickness of the integration layer advantageously varies from d to 10 cm, more advantageously from d to 8 cm, with d representing the diameter of the pipes.

[0191] As mentioned previously, the integration layer may be insulating.

[0192] In a complement or in an alternative, the method according to the invention may comprise a step, prior to the spreading of the asphalt mix forming the integration layer according to the invention, of application of a layer of insulating materials.

[0193] These insulating materials may for example be a layer of asphalt mix comprising the light aggregates described previously, a cellular glass thermal insulation that comes in the form of plates of 60 cm45 cm or 120 cm60 cm format, and composed of rigid and hermetically sealed glass beads sold under the name FOAMGLAS, polystyrene, etc.

[0194] Advantageously, the thermal conductivity, , of the layer of insulating materials is less than 1 W/m.Math.K.

[0195] This layer of insulating materials is advantageously implemented when the integration layer is not itself insulating. This layer of insulating materials may also fulfil the function of support layer.

[0196] An anchoring layer may be deposited on the integration layer. This anchoring layer makes it possible to improve the anchoring between the asphalt mix of the integration layer and the surface course or the binder course. It also makes it possible to protect the integration layer comprising the heat exchanger device.

[0197] The anchoring layer meets the specifications of the NF P 98-150-1 Standard of June 2010.

[0198] Advantageously, the method according to the invention comprises the following successive steps: [0199] aaa) If need be, application of a layer of insulating materials, then [0200] aa) If need be, application of an adhesion layer, then [0201] a) spreading at a temperature below 160 C. of the asphalt mix, comprising a granular fraction, a hydrocarbon-based binder, said asphalt mix being workable, having a workability, measured with a Nynas workability meter at the working temperature of the asphalt mix, of less than 400N, then [0202] b) depositing the pipes, said pipes having a crushing strength greater than 3000 N per linear metre of pipe at 100 C., a thermal expansion less than 200.10.sup.6 m/mK at 20 C., then [0203] c) indenting the deposited pipes into said integration layer by compacting said asphalt mix during the workability period of said asphalt mix, to form an integration layer comprising the pipes of a heat exchanger device; [0204] dd) applying an anchoring layer, advantageously a layer of cold asphalt mix, then [0205] d) applying a surface course.

[0206] The anchoring layer meets the specifications of the NF P 98-150-1 Standard of June 2010.

[0207] It is also possible to deposit above the integration layer or the anchoring layer, if need be, a coloured layer serving as visual warning.

[0208] The surface layers of the road surfacing constitute a thermal exchanger operating by capturing or restoring heat, as a function of the climate, of large surface area. In operation, a heat-transfer fluid circulates in the pipes connected to any suitable thermal system, including geothermal ground water at depth, a vertical geothermal probe, a heat pump, etc.

[0209] The invention also relates to a method for recycling a road surface according to the invention, comprising a heat exchanger device as defined previously, comprising the following successive steps: [0210] A. Breaking up and removing bound materials including the integration layer comprising the heat exchanger device; [0211] B. Recycling the elements recovered at the preceding step, without operation of sorting or separation of the elements of the heat exchanger device.

[0212] A sectional view of a road surfacing comprising on the surface a heat exchanger device is represented in FIG. 1.

[0213] The pipes 1, in which a heat-transfer fluid circulates, are indented into an integration layer 2. This integration layer 2 may be of high conductivity or insulating, depending on the nature of the granular fraction of the asphalt mix.

[0214] This integration layer 2 is deposited on a support layer 3, which could be an insulating layer. This support layer 3 is advantageously insulating when the integration layer 2 is not itself insulating.

[0215] On the integration layer 2 is deposited a surface course 4. This surface course 4 has a high conductivity and constitutes the heat exchanger that is going to capture solar energy or constitutes the surface to heat, notably with a view to snow clearance or ice clearance from the roadway.

[0216] In FIG. 2 is represented the integration layer 2 comprising the pipes 1 on which a surface course 4 is deposited.

[0217] In FIG. 3, an example of possible geometry of the pipes 1 in the integration layer 2 is represented.

[0218] An exploded view of the integration layer 2, of the pipes 1 and of the surface course 4 is represented in FIG. 4.

Protocols:

Workability:

[0219] A workability test carried out according to the 98-258-1 Standard, of 2013, and suited: [0220] with a Nynas workability meter (version designated large volume and having a width of 30 cm, a length of 32 cm and a height of 13 cm) [0221] to a compactness of the asphalt mix of 75% (void content: 25%) [0222] with a temperature below or equal to the working temperature (suitable temperature)

Compactness:

[0223] The compactness of a formula is measured by means of a gyratory shear press (NF EN 12697-31 of August 2007). A cylindrical test specimen of asphalt mix is compacted by combining a rotatory shear action and a resulting axial force applied by a power head.

[0224] This test makes it possible to determine the compactness of a test specimen for a given number of gyrations by measuring the associated test specimen height.

Laboratory Indentation Test:

[0225] An asphalt mix is implemented on a compacting test bench according to the NF P 12697-33 Standard of September 2007, in a mould of 500 mm180 mm dimensions at its working temperature. The compactness of the asphalt mix is taken to 75% by compacting with the roller. The pipes are positioned on the surface of the asphalt mix, transversally to the direction of circulation of the roller. They are maintained in place by a scotch tape placed in the direction of circulation of the roller. The pipes are indented into the asphalt mix by 6 to 10 passages of roller. The correct indentation of the pipe is assessed visually on two criteria: the shape of the imprint left by the pipe in the asphalt mix: this must be deep with a dimension close to the diameter of the pipe. The shape of the section of the pipe at the end of the test, said pipe must not be made oval.

Thermal Conductivity Measurements:

[0226] To determine the thermal conductivity, a cylindrical test specimen (diameter 16 cm, thickness that can vary, usually 5 cm to 10 cm) of the material to be characterised, after a maturation time of 14 days, is subjected to a difference in temperature: 25 C. on one face, 10 C. on the other face. The measurement of the thermal flux passing through it, the difference in temperature between the faces and the thickness of the test specimen make it possible to determine the thermal conductivity of the material using the relationship:

=.Math.T/L with: [0227] the thermal conductivity expressed in W/m.Math.K [0228] the thermal flux traversing the test specimen expressed in W/m.sup.2 [0229] T the difference in temperature at the edges of the test specimen expressed in C. or Kelvin [0230] L The height of the test specimen in mm

Crushing:

[0231] To determine the crushing strength of the pipes, a sample of pipe, of a length between 5 cm and 10 cm, is cut out. This sample is next placed for 2 hours in an oven at a temperature of 100 C. The crushing test is next carried out at the temperature of 100 C. The sample is next positioned, on its generating line, between the two parallel plates of a press, placed in a climatic chamber regulated to 100 C. The press imposes on the sample a displacement of 10 mm/min. The crushing strength value is determined when the diameter of the sample is divided by two compared to the initial diameter of the sample. It is expressed in Newtons per linear metre of pipe using the relationship:

Rt=Ft/Lt with: [0232] Rt: crushing strength of the pipe in N/m [0233] Ft: force developed to crush the pipe up to a reduction of half of its diameter in N [0234] Lt: length of the sample subjected to the test in mm

[0235] Thermal expansion: it is measured according to the NF EN ISO 2505 Standard, of September 2005,

Adherence to Bitumen:

[0236] The pipes adhere to the bitumen when the following criterion is met: the pipes are smeared with a cationic emulsion of 50/70 bitumen dosed at 65% by weight of bitumen in accordance with the NF EN 13808 Standard of August 2013 using a brush. After one minute, a visual examination is carried out. If the emulsion does not form beads on the surface the adherence of the pipe is sufficient.

[0237] The example that follows illustrates the invention and also presents comparative tests. It reports tests carried out in roadwork conditions.

Description of the Samples:

Pipes

[0238] Three types of pipes are evaluated: [0239] 1. PIPE 1: Pipe made of high density polyethylene, cross-linked with anti-oxygen barrier (AOB) of diameter of 20 mm and wall thickness of 1.9 mm. The expansion coefficient of this pipe is 140.10 m/mK at 20 C. The hot shrinkage, measured according to the NF EN ISO 2505 Standard of September 2005, is less than 3% (in an oven, at 150 C. for 60 min). The crushing strength measured at 100 C. is 3000 N per linear metre of pipe. [0240] 2. PIPE 2: Pipe made of high density polyethylene of diameter of 20 mm and wall thickness of 3 mm. The expansion coefficient of the HD-PE is 280.10.sup.6 m/mK at 20 C. The crushing strength measured at 100 C. is 10,000 N per linear metre of pipe. [0241] 3. PIPE 3: Pipe made of polypropylene of diameter of 17 mm and of wall thickness of 2.2 mm. The expansion coefficient of this pipe is 160.10.sup.6 m/mK at 23 C. The hot shrinkage, measured according to the NF EN ISO 2505 Standard of September 2005, is less than 2% (in an oven, at 150 C. for 60 min). The crushing strength measured at 100 C. is 4500 N per linear metre of pipe. [0242] 4. PIPE 4: Pipe made of high density polyethylene, cross-linked, of diameter of 16 mm and wall thickness of 2 mm. The expansion coefficient of this pipe is 140.10.sup.6 m/mK at 20 C. The hot shrinkage, measured according to the NF EN ISO 2505 Standard of September 2005, is less than 3% (in an oven, at 150 C. for 60 min). The crushing strength measured at 100 C. is 2500 N per linear metre of pipe.

Pipe Support

[0243] Several substrates were used as support for the pipe serpentines: [0244] 1. SUBSTRATE 1: Geo-grid roadway reinforcement made of glass fibre with mesh size of 25 mm25 mm, with adhesive surface integrated on one face. [0245] 2. SUBSTRATE 2: Geo-grid roadway reinforcement made of glass fibre with mesh size of 25 mm25 mm. [0246] 3. SUBSTRATE 3: Rails made of polypropylene making it possible to clip the pipes to maintain them in shape. [0247] 4. SUBSTRATE 4: Grassing slabs made of high density polyethylene.

[0248] The sheets of pipes are prefabricated according to several patterns: [0249] transversally (that is to say that the pipes will be arranged perpendicularly to the advancement of the roadworks implementing the plant mix) under a pattern having 4 to 6 parallel straight lines of 4.5 m, spaced apart by 30 cm, and 3 to 5 bends of which the angle of curvature is 180, or [0250] longitudinally (that is to say that the pipes will be arranged parallel to the advancement of the roadworks implementing the plant mix) under a pattern having 4 to 6 parallel straight lines of 4.5 m, spaced apart by 30 cm and 3 to 5 bends of which the angle of curvature is 180.

[0251] The PIPE 3 is prepared beforehand by thermoforming. The tube is laid hot by sprinkling hot water at 80 C. minimum using an apparatus consisting of a heater and an unwinder during step b) to give it the desired shape. During the indentation, there is no longer circulation of water in the pipes. The pipes, of a length of the order to 30 m, are open to the outside at each of the two ends and thus contain nothing other than ambient air.

Asphalt Mix Formula

[0252] The following asphalt mix, ASPHALT MIX-1 was used in the laboratory tests:

TABLE-US-00001 TABLE 1 % by weight compared to the total weight of the granular fraction Granular fraction Filler* (<0.063 mm) 9.8% Sand (0.063-2 mm) 30.8% Microdiorite/ THIVIERS Aggregates 2/10 mm 59.4% Microdiorite/ THIVIERS Bitumen 35/50 5.0%** Workability additive None Manufacturing temperature 160 C. Workability 300 N NF P 98-258-1 of 2013 Rutting (NF EN 12697-22, 2007) Number of cycles 30,000 Rutting (%) 9% PCG (NF EN 12697-31, 2007) Number of gyrations 60 Voids (%) 4.1 *filler = fines **% =, compared to the total weight of the plant mix

[0253] Hot produced asphalt mix without sequencing or foaming of the binder. The workability is provided by the manufacturing temperature and the granular backbone.

[0254] The following asphalt mix, PLANT MIX-2 was used in the laboratory tests:

TABLE-US-00002 TABLE 2 % by weight compared to the total weight of the granular fraction Granular fraction Filler* (<0.063 mm) 8.9% Sand (0.063-2 mm) 27.8% Microdiorite/ THIVIERS Aggregates 2/10 mm 63.3% Microdiorite/ THIVIERS Bitumen 13/20 5.4%** Workability additive None Manufacturing temperature 160 C. Workability 500 N NF P 98-258-1 of 2013 Rutting (NF EN 12697-22, 2007) Number of cycles 30,000 Rutting (%) 3.2% PCG (NF EN 12697-31, 2007) Number of gyrations 60 Voids (%) 5.1 *filler = fines **% =, compared to the total weight of the asphalt mix

[0255] Hot produced asphalt mix, without sequencing.

[0256] The following asphalt mix, ASPHALT MIX-3 were used in the worksite test plate tests:

TABLE-US-00003 TABLE 3 % by weight compared to the total weight of the granular fraction Granular fraction Filler* (<0.063 mm) 8.3% Sand (0.063-2 mm) 37.1% SGC Aggregates 2/8 mm 56.5% SGC Bitumen 35/50 5.0%** Workability additive 0.4% Manufacturing temperature 140 C. Workability 350 N NF P 98-258-1 of 2013 Rutting (NF EN 12697-22, 2007) Number of cycles Rutting (%) PCG (NF EN 12697-31, 2007) Number of gyrations 60 Voids (%) 5.4 *filler = fines **% =, compared to the total weight of the asphalt mix

[0257] Hot produced asphalt mix without sequencing or foaming of the binder. The workability is provided by the workability additive and the granular backbone.

[0258] The workability additive is a hydrogenated ricin oil having the following characteristics:

TABLE-US-00004 Melting point ( C.) 84-89 Acid index (mg KOH/g) 2 Saponification index (mg KOH/g) 174/186 Iodine index (gl.sub.2/100 g) 3.5 Hydroxyl index (mg KOH/g) 155-165 Acetyl index 139 Unsaponifiables (%) 1.0

[0259] This hydrogenated ricin oil has, after saponification, approximately the following fatty acid composition (percentages expressed by weight compared to the total weight):

[0260] 87% of 12-hydroxy-octadecanoic acid

[0261] 11% of stearic acid

[0262] 2% of palmitic acid

[0263] traces of (9, 10)-dihydroxystearic acid

Results

[0264] For SUBSTRATES 1 to 3, the prefabricated sheet is arranged directly on the plant mix at the paver output before being indented by the compactor. The paver is of ABG 7820 type with a screed width adjustable from 2.5 to 5 m; it made it possible to lay a 5 m wide road in a single pass. The compactor is of Hamm DV 90 type (tandem vibrant), its weight is around 9 tonnes.

[0265] The results are reported in the following table:

TABLE-US-00005 TABLE 4 Nature of the pipe Substrate Realisation Observations PIPE 1 SUBSTRATE 1 The sheet is arranged Lack of adherence of the pipe SUBSTRATE 2 transversally directly on Lack of rigidity of the pipe the asphalt mix at the (crushing, flattening of the pipe) paver output before for this workability of asphalt mix being indented by the compactor PIPE 1 SUBSTRATE 1 The sheet is arranged Difficulty of implementation: SUBSTRATE 2 longitudinally directly on lack of adherence implying a the asphalt mix at the displacement leading to the paver outlet before being destruction of the prefabricated indented by the sheet compactor PIPE 2 SUBSTRATE 1 Sheets of pipes fixed onto Rigidity of the pipes sufficient: No SUBSTRATE 2 adhesive and non- ovalisation of the pipe adhesive grids are Adherence of the pipe satisfactory arranged transversally Significant thermal shrinkage directly on the asphalt leading to the exiting of the pipes mix at the paver outlet at the level of the bends before being indented by No significant difference as a the compactor function of the substrate PIPE 2 SUBSTRATE 1 The sheet is arranged Difficulty of implementation SUBSTRATE 2 longitudinally directly on longitudinally: displacement of the the asphalt mix at the sheet during the compacting step paver output before being indented by the compactor PIPE 3 SUBSTRATE 1 The sheet is arranged Rigidity of the pipes sufficient: no transversally directly on ovalisation of the pipe the asphalt mix at the Adherence of the pipe satisfactory paver outlet before being No shrinkage of the pipes which indented by the remain indented compactor PIPE 3 SUBSTRATE 1 The sheet is arranged Rigidity of the pipes sufficient: No transversally ovalisation of the pipe longitudinally directly on Satisfactory adherence of the pipe the asphalt mix at the The pipes remain indented paver outlet before being indented by the compactor PIPE 1 SUBSTRATE 4 A pipe serpentine is fixed Destruction of the sheet on the onto stabilisation slabs passage of the paver: before application of the The sheets are not integral with asphalt mix the ground support and are deformed on the passage of the paver. Outside The shaped pipes are The pipes deform during the the deposited on the ground passage of the paver, that is to say method and held by clips before during the application of the according application of the asphalt asphalt mix to the mix Appearance of surface fissuring invention - INVPIPE 3

[0266] It emerges from this series of tests that the choice of a workable (350 N) 0/6 asphalt mix makes it possible to indent the pipes, not protected, without deforming or damaging them, from the moment that they are sufficiently rigid (crushing strength greater than 4500 N per linear metre of pipe at 100 C.), and for this type of asphalt mix, adherent to the bitumen. In a workable (350 N) 0/6 asphalt mix, a pipe having a crushing strength greater than 4500 N per linear metre of pipe at 100 C. and a controlled thermal expansion (expansion coefficient less than 160.10.sup.6 m/mK at 20-25 C.) makes it possible to obtain satisfactory results without thermal and/or mechanical protection means, in particular without cooling or without pressurisation.

[0267] The integration layer is necessary and sufficient to protect the pipes during the passage of site machinery.

[0268] When the pipes may be shaped by shape memory, the use of a substrate does not seem useful.

[0269] It should be noted that to indent less rigid pipes (crushing strength between 3000 N and 4500 N per linear metre of pipe at 100 C.), it is necessary to increase the workability of the asphalt mix.

[0270] Other laboratory results:

[0271] Indentation tests were carried out at the laboratory model scale.

[0272] The results are reported in the following table:

TABLE-US-00006 TABLE 5 PIPE-1 PIPE-2 PIPE-3 PIPE-4 ASPHALT MIX-1 Satisfactory Satisfactory Satisfactory Pipe totally Very workable indentation indentation indentation crushed Without additive ASPHALT MIX-2 Poor Satisfactory Poor Pipe totally Not very indentation with indentation indentation with crushed workable ovalisation of ovalisation of Without additive the pipe the pipe ASPHALT MIX-3 Poor Satisfactory Satisfactory Pipe totally Workable indentation with indentation indentation crushed With additive ovalisation of the pipe