EP2337819A1

EP2337819A1 - High-modulus bituminous mix based on recycled materials

Info

Publication number: EP2337819A1
Application number: EP09744740A
Authority: EP
Inventors: Gilles Gauhtier; Alain Montpeyroux
Original assignee: Total Raffinage Marketing SA
Current assignee: TotalEnergies Marketing Services SA
Priority date: 2008-10-14
Filing date: 2009-10-12
Publication date: 2011-06-29
Also published as: WO2010043945A1; FR2937059A1

Abstract

The present invention relates to a high-modulus bituminous mix according to the NF P 98-140 standard or the NF EN 13108-1 standard based on recycled roadway material millings comprising a residual bituminous binder, based on fresh aggregates and based on bituminous binder (residual bituminous binder plus additional bituminous binder), the bituminous binder content in the mix being between 5.5 and 6.5% by weight. The performance of the bituminous mix is equivalent and even superior to that of a high-modulus mix. The high-modulus mixes according to the invention have a modulus of rigidity E*, measured at 15°C and at 10 Hz, of greater than 15 × 103 MPa and a reversed bending fatigue strength e6, at 10°C and at 25 Hz, of greater than 140 × 10-6.

Description

HIGH MODULE ENROBE BASED ON RECYCLING MATERIALS

TECHNICAL AREA

The present invention relates to a high-modulus bituminous mix according to standard NF P 98-140 or NF EN 13108-1 obtained from recycling materials, and more particularly from recycling charges for roadway materials.

The invention also relates to the use of these high-modulus bituminous mixes, in the preparation of road pavements, in particular in the preparation of base layers or roadbed layers. TECHNICAL CONTEXT / PRIOR ART

Conventionally, pavements are covered with bituminous mixes a few centimeters thick. After a number of years, these coatings age due to deformations caused by traffic, weather conditions and light. These different parameters result in hardening of the bituminous mix by evaporation of the lightest fractions of the bituminous binder contained in said bituminous mix. This results in a weakening of the bituminous mix which becomes brittle and has a tendency to crack. It is therefore necessary to treat the pavement surface after a number of years. One solution is to mill the surface of the bituminous mix with a machine and replace it with a new bituminous mix. During this operation, pavement materials called "costs" are recovered. These mills are aggregates surrounded by a film of bituminous binder. The increase in prices of petroleum products, especially bitumen and the development of resources, especially oil, have led tankers and truckers to take an interest in the recycling of these costs and their reuse for the maintenance or construction of roadways. These economic and environmental concerns should not, however, be to the detriment of the performance of bituminous mixes in place. The incorporation of the costs must therefore take into account the standards established for asphalt mix performance. The incorporation of costs in bituminous mixes requires a good knowledge of the costs and an optimization of the mixture costs / new aggregates / bituminous binder.

Thus, in the patent granted EP0959105, the applicant company has successfully incorporated costs into bituminous mixes while maintaining acceptable mechanical performance. Thus, the bituminous mixes described have a modulus of rigidity equivalent to that of a severe bitumen according to standard NF P 98-138. GOALS

In the continuity of its work, the applicant company applied itself to formulate bituminous mixes including costs to obtain high modulus bituminous mixes (EME) according to standard NF P 98-140 or NF EN 13108-1. Another object of the invention is to provide bituminous mixes comprising mills having performance equivalent to or greater than that of high-modulus bituminous mixes (EME), particularly with regard to the resistance to rutting, of the modulus of rigidity, fatigue resistance and resistance to cracking. Another object of the invention is to provide high modulus bituminous mixes (EME) comprising costs for reducing the thickness of bituminous mixes.

Another object of the invention is to provide high modulus mixes (EME) comprising costs to increase the life of bituminous mixes.

BRIEF DESCRIPTION

In the first place, the present invention relates to a high modulus bituminous mix according to standard NF P 98-140 or NF EN 13108-1 based on recycling charges for roadway materials comprising residual bituminous binder, based on new aggregates and based on bituminous binder, said mix comprising between 40 and 60% by weight of blends and 5.5 to 6.5% by weight of bituminous binder (residual bituminous binder and bituminous binder), relative to to the total mass of bituminous mix.

The high-modulus bituminous mix has a modulus of stiffness E *, measured at 15 ° C and 10 Hz, greater than 15.10 ³ MPa and an alternating flexural fatigue resistance ε ₆ at 10 ⁰ C and 25 Hz , greater than 140.10 ^"6 .

The high modulus bituminous mix comprises between 40 and 60% by weight of new aggregates, relative to the total weight of the bituminous mix.

The charges have a residual bituminous binder content of between 2 and 6% by weight, relative to the total mass of the costs.

The residual bituminous binder of the charges has a penetrability at 25 ^° C. of between 5 and 40 1/10 mm, preferably between 10 and 30 1/10 mm.

The bituminous binder content is between 1 and 5% by weight, relative to the total weight of the bituminous mix. The bituminous filler, has a penetration at 25 ° C between 10 and

50 1/10 mm, preferably between 20 and 30 1/10 mm. The bituminous binder (residual bituminous binder and bituminous binder) has a penetrability at 25 ° C of between 10 and 1/10 mm, preferably between 15 and 25 1/10 mm.

The vacuum content according to the NF P 98-252 standard is less than or equal to 5%. Secondly, the invention relates to the use of high modulus bituminous mix as defined above in the road industry, for the production of base layers or pavement layers for pavements.

Finally, the invention relates to a method for preparing a high modulus bituminous mix as defined above, said method comprising mixing, at a temperature of between 12O ⁰ C and 220 ° C, preferably between

160 ° C and 18O ⁰ C, a bituminous binder, new aggregates and recycling costs.

Preferably, the charges are introduced after the mixing of the new aggregates and the bituminous binder.

DETAILED DESCRIPTION

The invention relates to a bituminous mix based on mills, new aggregates and bituminous binder having the performance of a high modulus bituminous mix. High modulus bituminous mixes or "EME" are defined in standard NF P 98-140 or NF EN 13108-1. High modulus bituminous mixes are distinguished from other bituminous mixes in terms of rigidity modulus, rut resistance and fatigue resistance. In terms of mechanical performance, the name EME translates, in standards NF P 98-140 or NF EN 13108-1, by one or more of the following minimum performances:

a complex modulus of rigidity measured at 15 ^° C., 10 Hz greater than 14,000 MPa,

- fatigue strength, measured in the 2-point bending test, greater than 100.10 ^-6 for the Class 1 EME and greater than 130.10 ^-6 for the Class 2 EME,

- rut depth less than 7,5%, - resistance to stripping measured by the Duriez test greater than 0,70 for class 1 EME and greater than 0,75 for class 2 EME (NF P 98-140) or an ITSR water sensitivity greater than 70% (NF EN 13108-1),

- a vacuum content of less than 10% for class 1 EME and less than 6% for class 2 EME. These values, and in particular the high values of modulus and fatigue resistance, as well as the low value ruts, give the EMEs mechanical performance superior to most bituminous mixes. EMEs thus have the ability to withstand creep and traffic-related efforts and to maintain the properties of the bituminous mix according to the repetition of the application of the charges, which gives the material a high resistance to the phenomenon of ruin by fatigue. The mechanical characteristics of EMEs also allow them to have a reduced thickness compared to conventional bituminous mixes, while retaining good properties. EMEs are generally used at thicknesses of 5 to 12 cm, preferably 6 to 8 cm. The thickness depends on the particle size of the mixture. For EME of particle size 0/10 (that is to say aggregates whose dimensions are less than 10 mm), the thickness is 6 to 8 cm. For EME of particle size 0/14, the thickness is 7 to 13 cm. For EME of particle size 0/20, the thickness is 9 to 15 cm. EMEs are generally used for foundation layers and basecoats.

EMEs are conventionally formulated from bituminous binder and new aggregates. In the EMEs according to the invention, charges are added. The bituminous mixes according to the invention comprise at least 30% of costs, relative to the total mass of the bituminous mix. Preferably, the bituminous mix comprises between 30 and 70% by weight of charges, relative to the total mass of the mix, more preferably between 40 and 60% by weight.

For the purposes of the present invention, the term "mills" means pavement materials obtained by milling the surface of roads. The costs are thus mixtures bituminous binding / aggregates. In particular, the charges are aggregates covered with a film of bituminous binder. This bituminous binder present in the mills is called a "residual" bituminous binder, as opposed to the bituminous binder additionally added to the new aggregates to form the bituminous mixes according to the invention. This residual bituminous binder is generally a bitumen which has aged, has been oxidized and therefore has low penetrability. It is possible to know the content and the penetrability of the residual binder of the costs by extraction of the binder.

The charges used have a residual bituminous binder content of 2 to 6% by weight relative to the total mass of the charges, preferably 4 to 6% by weight relative to the total mass of the costs.

The penetrability at 25 ⁰ C of the residual bituminous binder costs is between 5 and 40 1/10 mm, preferably between 10 and 30 1/10 mm (according to standard NF EN 1426). The residual bituminous binder is therefore a particularly hard binder. To obtain a particularly hard residual bituminous binder, it is possible to mill roads composed of draining asphalt. In fact, since the draining mixes are asphalts with a high void content, they are mixes whose binder oxidizes more easily, and therefore mixes whose binder is particularly hard. The granulometry of the charges is between 0 and 20 mm, preferably between 0 and 14 mm, preferably between 0 and 10 mm. To be able to be within the specified size ranges, the charges may be crushed and sieved. The bituminous mix according to the invention also comprises new aggregates.

The bituminous mixes comprise between 30 and 70% by weight of new aggregates, relative to the total weight of the bituminous mix, preferably between 40 and 60% by weight.

The new aggregates according to the invention have usual particle sizes 0/10, 0/14, 0/20. The chemical nature of the aggregates does not pose any particular problems.

Calcareous or predominantly calcareous aggregates are preferred. The mechanical and manufacturing characteristics, concerning the angularity, the cleanliness of the aggregates are specified in the standard XP P 18-540.

The bituminous mix according to the invention optionally comprises a mineral filler portion having a particle size of less than 63 μm added to the other granular fractions. The bituminous mix according to the invention comprises between 1 and 5% by weight of filler, relative to the total weight of the mix, preferably between 1 and

3% by mass.

The new aggregates, the filler and the mills constitute the granular skeleton of the bituminous mix. It is necessary to know the particle size of each of these constituents in order to be able to develop a particle size curve of the type of a high modulus bituminous mix.

The bituminous binder additionally supplies the residual bituminous binder provided by the costs. This bituminous binder, just like the residual bituminous binder, consists of pure bitumen, modified bitumen or special bitumen, taken alone or mixed. We can first mention bitumen of natural origin, those contained in deposits of natural bitumen, natural asphalt or oil sands. The bitumens according to the invention are also bitumens derived from the refining of crude oil. Bitumens come from the atmospheric and / or vacuum distillation of oil. These bitumens can be optionally blown, vis-reduced and / or deasphalted. Finally, the bitumens according to the invention may also be bitumen called "synthetic", pigmentable or colorable, containing no or little asphaltenes. The bitumens may be bitumens / polymers containing optionally crosslinked elastomers or plastomers. Fluxed bitumens may also be used with petroleum oils and / or vegetable oils. The residual bituminous binder can of course come from the various bitumens mentioned above, taken alone or in mixtures. The bituminous binder content is between 1 and 5% by weight, relative to the total weight of the bituminous mix.

It is necessary to use a bituminous binder whose penetrability is between 10 and 50 1/10 mm, preferably between 20 and 30 1/10 mm (according to standard NF EN 1426).

The penetrability of the bituminous binder (residual bituminous binder and bituminous filler) is between 10 and 1/10 mm, preferably between 15 and 25 1/10 mm (according to standard NF EN 1426). The penetrability of the bituminous binder (residual bituminous binder and bituminous binder) is very important, the bituminous binder must be particularly hard. The amounts of residual bituminous binder and of bituminous binder, as a function of their penetrability, will be adjusted to obtain a bituminous binder in the end, which is particularly hard, that is to say, according to the invention, a bituminous binder in the end. having a penetrability is between 10 and 1/10 mm, preferably between 15 and 25 1/10 mm, preferably around 1/10 mm.

The total content of bituminous binder (residual bituminous binder and bituminous binder) is extremely important and must be between 5.5 and 6.6% by mass relative to the weight of the bituminous mix to obtain the EME according to the invention. The selection of this particular range for the bituminous binder content gives the bituminous mixes particularly good mechanical properties especially in rut resistance, fatigue resistance and rigidity modulus. Bituminous mixes according to the invention have the properties of EME and even properties superior to EME. Thus, the EMTs according to the invention have both a rigidity modulus E *, measured at 15 ° C. and at 10 Hz, greater than 15 × 10 ³ MPa and an alternating flexural fatigue strength, at 10 ° C. and at 25 ° C. Hz, greater than 140. 10 ^"6 .

Similarly, the void content of EMEs according to standard NF P 98-252 is less than 5%. These high-modulus bituminous mixes are therefore particularly resistant and indicated for their use in particular in the road industry, for the production of base layers or pavement layers for pavements.

To prepare these high-modulus bituminous mixes, new aggregates, possibly the filler, of the bituminous binder and blends are mixed. Before mixing these different constituents, it is desirable to dry the new aggregates, the filler and the mills. Preferably, the new aggregates and optionally the charge are dried in an oven at a temperature between 160 ° C and 18O ⁰ C for a duration greater than 16 hours. At a constant temperature, the charges must not be heated for so long, to avoid the effect of agglomeration, clumping of the costs. For a temperature of 160 ° C to 180 ° C, the drying time is less than 8 hours. One could also consider heating at a lower temperature for an equivalent period of 16 hours. After drying of new aggregates, and optionally filler, and milled, are mixed at a temperature between 120 ° C and 220 ⁰ C ₅ preferably between 16O ⁰ C and 180 ⁰ C, the new aggregates, optionally of the load , mills and bituminous binder. Preferably, the new aggregates are first mixed, possibly with the filler with bituminous binder, and then the charges are added. Typically, the method comprises the following steps:

(i) heating the new aggregates and optionally the filler to a temperature between 160 ⁰ C and 180 ⁰ C for at least 16 hours, (ii) heating the milled material at a temperature comprised between 16O ⁰ C and 18O ⁰ C maximum for 8 hours,

(iii) mixing the new aggregates and optionally the filler, at a temperature of between 180 ^° C. and 180 ^° C. for a few seconds, (iv) adding, at a temperature of between 160 ^° C. and 180 ^° C., the bituminous binder; adding to the mixture obtained in step (iii) and mixing for 5 to 10 seconds,

(v) adding the blends to the mixture obtained in step (iv) and mixing from 60 to 90 seconds.

EXAMPLES Three bituminous mixes A, B and C according to the invention and two control bituminous coatings Tj and T _{2 are} prepared from:

- mills containing 5% by mass of residual bituminous binder of penetrability 29 1/10 mm (according to standard NF EN 1426),

- new aggregates of 0/20 mm particle size in accordance with XP P 18-540, with a calcareous load and,

- bituminous binder providing penetration 12 1/10 mm (according to standard NF EN 1426).

The bituminous mixes are prepared in the following manner: the charges are brought to the temperature of 18O ⁰ C for a duration of about 8 hours, the new aggregates and the calcareous load are brought to the temperature of 18O ⁰ C for a longer duration at 16 o'clock, the new aggregates and the calcareous filler are mixed in a thermoregulated mixer type LPC 85 L at 18O ⁰ C for 10 seconds, the bituminous binder addition to 18O ⁰ C is added and the bituminous binding additive / aggregates new The batch is blended at 180 ° C for 10 seconds, the blends are then added and mixed with the bituminous binder / new aggregate / filler at 180 ^° C for 90 seconds. The mass concentrations of the various constituents are given in Table I below. The values are given as a percentage by mass throughout the bituminous mix.

Table I

The mechanical performances of bituminous mixes are given in Table II below and compared to the performances required to obtain the designation Asphalt bitumen with High Modulus (EME): Table II

^ - * Compressive shear press compactability test (PCG) according to standard NF P 98-252 or NF EN 12697-31 and NF EN 12697-10, reflects the capacity of the bituminous mix to be put in place with a specified compactness.

⁽²⁾ Water stripping resistance test according to standard NF P 98-251-1, reflects the adhesion between the bituminous binder and the aggregates.

⁽³⁾ Test of resistance to smearing according to standard NF P 98-253-1 or NF EN 12697-22, reflects the capacity of the bituminous mix to resist the creep related to the application of the traffic.

⁽⁴⁾ Measurement of the complex stiffness modulus according to standard NF P 98-260-1 or NF EN 12697-26, reflects the ability of asphalt to withstand the forces.

2-point flexural fatigue test according to standard NF P 98-261-1 or NF EN 12697-24, reflects the ability of the bituminous mix to maintain the properties of the bituminous mix according to the repetition of the application of the charges.

Gyratory shear press (GCP) compaction tests yielded void rates of 1.5-5.0%. All bituminous mixes are therefore quite compact and meet the EME standard.

The Duriez de-coating tests show that the adhesion between the bituminous binder and aggregates is good enough for all bituminous mixes and that they therefore meet the EME standard. The shading tests give rut values of 0.9 to 4% with respect to the thickness of the test piece (10 cm), ie from 0.9 to 4 mm. All bituminous mixes meet the EME standard and therefore have good hot performance.

The complex modulus tests demonstrate that the bituminous binder content (bituminous feedstock + residual bituminous binder) of the bituminous mix is decisive for satisfying the EME standard. Indeed, the bituminous mix T ₂ too rich in binder, does not meet the standard, since it has a module less than 14 000 MPa. Bituminous mixes according to the invention A, B, C have modules greater than 14000 MPa. For these bituminous mixes, these high module values make it possible to envisage reductions in pavement thickness, all the more so since the value of the module is high.

The fatigue strength tests demonstrate once more that the bituminous binder content (bituminous feedstock + residual bituminous binder) of the bituminous mix is decisive for meeting the EME standard. This time, it is the bituminous control coating Ti too poor in binder that has a low resistance to fatigue, the other bituminous mixes have a much higher fatigue behavior.

The bituminous mixes Tj and T ₂ , the binder content of which has not been finely selected, do not simultaneously exhibit good behavior in terms of modulus of rigidity and fatigue resistance, and can not be considered as EMEs. Only the bituminous mixes according to the invention, the bituminous binder content of which has been adjusted simultaneously exhibit good behavior in the form of modulus of rigidity and fatigue resistance, and are therefore comparable to EMEs. The bituminous asphalt that is better able to withstand the forces, able to maintain its properties according to the repetition of the application of the fillers and allowing a greater reduction of the roadway thicknesses, is bituminous asphalt A. The performance of bituminous mixes according to the the invention were not degraded by the addition of costs and are even comparable to those of conventional EMEs without charges. It is therefore possible to combine mechanical performance and sustainable development with bituminous mixes according to the invention.

Asphalt mixes A and T ₂ were then compared using the French pavement design method developed by SETRA using "Alizé" software. This method compares the long-term behavior of pavement structures including asphalt mix for different traffic and climate conditions. For a given traffic and a given lifetime, the software gives an estimate of the thickness that the asphalt must have (taking into account complex modulus and fatigue values). For each mix, the assumptions are as follows: a traffic of 600 trucks per day for 30 years with an annual geometric increase of 2%, a pavement structure including a thickness in cm "x" of asphalt on a platform support PF3 of 120 MPa lift, asphalt and the platform is not glued.

Table III

For a traffic of 600 trucks per day for 30 years, the software "Alizé" gives a thickness of "x" asphalt of 12 cm for the asphalt A. Under the same traffic conditions, the thickness "x" of the asphalt T ₂ is 21 cm. The mix A according to the invention, will therefore be able to withstand a traffic of 600 trucks per day for 30 years with a thickness almost twice as low as that of the mix T ₂ under the same conditions. The asphalt A according to the invention thus makes it possible to significantly reduce the thickness of the roadway, while being also resistant.

Claims

1. High modulus bituminous mix according to Standard NF P 98-140 or NF EN 13108-1, based on recycling charges for roadway materials comprising residual bituminous binder, based on new aggregates and based on bituminous binder. supply, said mix comprising between 40 and 60% by weight of charges and 5.5 to 6.5% by weight of total bituminous binder (residual bituminous binder and bituminous binder), relative to the total mass of bituminous mix.

High modulus bituminous mix according to claim 1, having a modulus of rigidity E *, measured at 15 ° C. and at 10 Hz, greater than 15 × 10 ³ MPa and an alternating flexural fatigue resistance ε ₆ at 10 ° C. and at 25 Hz, greater than 140.10 ⁶ .

3. high modulus bituminous mix according to claim 1 or 2 comprising between 40 and 60% by weight of new aggregates, relative to the total weight of the bituminous mix.

4. A high modulus asphalt mix according to any one of claims 1 to 3 wherein the charges have a residual bituminous binder content of between 2 and 6% by weight, based on the total weight of the charges.

The high modulus asphalt binder of claim 4 wherein the residual bituminous binder of the packs has a penetrability at 25 ° C of from 5 to 40 1/1 mm.

6. asphalt high modulus asphalt according to any one of claims 1 to 5 wherein the bituminous binder content of the filler is between 1 and 5% by weight, relative to the total weight of the bituminous mix.

7. A high modulus asphalt mix according to any one of claims 1 to 6 wherein the bituminous binder additive has a penetrability at 25 ⁰ C ₅ between 10 and 50 1/10 mm.

8. Asphalt high modulus asphalt according to any one of claims 1 to 7 wherein the bituminous binder (residual bituminous binder and bituminous binder filler) has a penetrability at 25 ⁰ C, between 10 and 1/10 mm .

9. High modulus bituminous mix according to any one of claims 1 to 8 wherein the vacuum content according to NF P 98-252 is less than or equal to 5%.

10. Use of the high-modulus asphalt according to any one of claims 1 to 9, in the road industry, for the production of basecoats or pavement layers for pavements.

A process for the preparation of a high modulus bituminous mix according to any one of claims 1 to 9, said method comprising mixing, at a

.3 temperature between 120 ⁰ C and 220 ⁰ C ₃ preferably between 160 ⁰ C and 180 ⁰ C, new aggregates, bituminous binder and recycling costs.

12. A method of preparing a high modulus asphalt mix according to claim 11, wherein the charges are introduced after mixing new aggregates and bituminous binder additive.