Process and unit for treating bituminous road waste, process and unit for manufacturing bituminous coating

Abstract

Method and unit for treating bituminous road waste, method and unit for manufacturing bituminous coating Method for treating bituminous road waste in which, by gravimetric sorting of the road waste, batches of aggregates for bituminous coating are produced, the aggregates for bituminous coating of each batch having a density less than a predetermined maximum density and / or greater than a predetermined minimum density. Method for manufacturing bituminous coating, in which a bituminous coating is manufactured by mixing a plurality of components including at least one batch of aggregates for bituminous coating, the aggregates for bituminous coating of said at least one batch having a density less than a predetermined maximum density for the batch and / or greater than a predetermined minimum density for the batch.Road waste treatment and bituminous coating manufacturing units for the implementation of these processes. Figure for the abstract: Fig. 1.

Description

Title of the invention: Method and unit for treating bituminous road waste, method and unit for manufacturing bituminous coating Technical field

[0001] The present disclosure relates to the treatment of road waste and the manufacture of bituminous coating. Prior art

[0002] To remedy the wear of road surfaces made of bituminous coating, it is necessary to periodically redo these surfaces. This operation involves first removing the old surface, then creating a new one.

[0003] The removal of the old coating by milling produces a considerable quantity of waste, known as road waste. This is partly recycled, after screening (sieving) and crushing operations, in the form of aggregates for bituminous coating, which are incorporated into new bituminous coatings and consequently, into new road surfaces.

[0004] However, with this process, the proportion of aggregates for bituminous coating used in the manufacture of bituminous coatings remains low, due to the variability of the physical characteristics of these aggregates. For this reason, the average recycling rate of road waste in France, in 2019, still remains below 20%. An example of a bituminous coating manufacturing process in which road waste is incorporated into the manufactured coating, is provided by the document:

[0005] Zhang, K., Huchet, F., & Hobbs, A. (2019). A review of thermal processes in the production and their influences on performance of asphalt mixtures with reclaimed asphalt pavement (RAP). Construction and Building Materials, 206, 609-619.

[0006] It is therefore desirable to propose methods and units for treating road waste and / or manufacturing bituminous coating which make it possible to increase the proportion of recycled road waste in the bituminous coatings manufactured to create new roads or new surface coverings. Statement of the invention

[0007] A first objective of the invention is to propose a method for treating bituminous road waste which can be part of an industrial process making it possible to increase the proportion of recycled road waste in road surfaces.

[0008] To achieve this objective, in accordance with the present disclosure, the following method for treating bituminous road waste is proposed. This method comprises the following step:

[0009] S140) by gravimetric sorting of bituminous coating aggregates, at least one batch of aggregates for bituminous coating is produced, the aggregates for bituminous coating of each batch of said at least one batch having a density less than a maximum density predetermined for the batch and / or greater than a minimum density predetermined for the batch.

[0010] Gravimetric sorting (or gravimetric separation) is a sorting operation in which aggregates are separated according to their density (or, equivalently, their density (relative to water)). The gravimetric sorting operation carried out in step S140 makes it possible to produce several batches of aggregates; for each batch thus produced, the density of the aggregates is either less than a minimum reference value, or between two reference values, or greater than a maximum reference value.

[0011] In some embodiments, in step S140, the gravimetric sorting is performed using a water, aqueous suspension, or air gravimetric separator.

[0012] In certain embodiments, at least two gravimetric separators (or two gravimetric sorting separation steps) are carried out successively, in order to sort the aggregates more finely.

[0013] In some embodiments, the method for treating bituminous road waste further comprises the steps:

[0014] SI 10) bituminous road waste is provided;

[0015] S120) bituminous road waste is crushed; and

[0016] a maximum permitted diameter being defined as a function of a maximum diameter of the natural aggregates present in said road waste,

[0017] S130) by screening said road waste, after the crushing step, aggregates with a diameter less than the maximum permitted diameter are separated from aggregates with a diameter greater than the maximum permitted diameter; and

[0018] the gravimetric sorting step S140 is carried out only for aggregates with a diameter less than said maximum permitted diameter.

[0019] In certain embodiments, the aggregates which, at the end of the crushing operation, have a diameter greater than the maximum permitted diameter (or possibly the maximum diameter of the natural aggregates present in said road waste) are returned to the crushing installation to undergo the crushing operation S120 again.

[0020] In certain embodiments, a minimum permitted diameter is defined as a function of a minimum diameter of the aggregates that can be sorted during the gravimetric sorting operation; the minimum permitted diameter may for example be equal to this latter diameter.

[0021] In this case, preferably, during step S130 of screening the road waste, the aggregates with a diameter less than the minimum permitted diameter are separated from the aggregates with a diameter greater than the minimum permitted diameter.

[0022] In addition, the gravimetric sorting step S140 is then carried out only for aggregates with a diameter greater than the minimum permitted diameter.

[0023] In addition to the method for treating bituminous road waste presented previously, in accordance with the present disclosure, a method for manufacturing bituminous coating is proposed. This method comprises a manufacturing step S200, during which the bituminous coating is manufactured by mixing a plurality of components including at least one batch of aggregates for bituminous coating, the aggregates for bituminous coating of each batch of said at least one batch having a density less than a maximum density predetermined for the batch and / or greater than a minimum density predetermined for the batch.

[0024] Advantageously, the information relating to the minimum and / or maximum density of the aggregates of said at least one batch of aggregates (which are typically the batch(es) of aggregates produced during step S140 of the preceding road waste treatment method) can be used to optimize the manufacture of road coatings, and this in different ways. This information can be used for example to optimize the formulation of the coating, and / or manufacturing parameters, for example during heating operations and / or addition of additives.

[0025] Thus in certain embodiments, at least one parameter of a machine used in the manufacturing step S200 is determined as a function of the maximum and / or minimum density of the aggregates of said at least one batch of aggregates for bituminous coating.

[0026] In certain embodiments, the manufacturing step S200 comprises a sub-step S210 during which a formulation of the bituminous coating is obtained, the formulation taking into account the maximum and / or minimum density of the aggregates of said at least one batch of aggregates for bituminous coating; and in step S200, the bituminous coating is manufactured in accordance with said formulation.

[0027] In some embodiments, the manufacturing step S200 comprises a sub-step:

[0028] S230) heating is carried out on a mixture comprising at least one heated batch among said at least one batch of aggregates for bituminous coating; and

[0029] at least one heating parameter of said mixture, for example the heating temperature or a residence time in a furnace, is determined as a function of the maximum and / or minimum density of the aggregates of said at least one heated batch.

[0030] In certain embodiments, during the manufacturing step S200, at least one additive is injected, and at least one parameter relating to the injection of additive, by for example the proportion of additive, the nature of additive, etc., is determined based on the maximum and / or minimum density of the aggregates of at least one batch among said at least one batch of aggregates for bituminous coating.

[0031] In certain embodiments, said at least one batch of aggregates for bituminous coating used for the manufacture of the coating is obtained by the process for treating bituminous road waste defined above.

[0032] The methods for treating bituminous road waste and for manufacturing bituminous coating according to the present disclosure make it possible to produce bituminous coatings in which the proportion of aggregates for bituminous coating from road waste is increased compared to prior methods.

[0033] Indeed, it has been noted that the density of aggregates for bituminous coating is strongly correlated with the bitumen content of these aggregates. According to the present disclosure this property is exploited by separating the aggregates for bituminous coating according to their density. This makes it possible to obtain different batches of road aggregates, such that for each batch, the minimum and / or maximum density of the aggregates in the batch is known and consequently, an approximate value of the maximum and / or minimum bitumen content of the aggregates is available. Thanks to this information, these batches can be used to the best advantage (in particular: in the greatest possible proportion) for the manufacture of bituminous coatings. In addition, the manufacturing process itself can be optimized.

[0034] The manufacturing process can naturally be optimized all the more if a large number of batches of aggregates with different densities are prepared in step S140. In this case, with the exception of the batches with the lowest and highest densities, for the other batches the densities of the aggregates in the batch, or 'batch densities', can be estimated based on the maximum and minimum densities of the aggregates in the batch. The manufacturing of road asphalt can then be optimized based on these batch densities.

[0035] It should also be noted that the step of sorting the aggregates according to their density, carried out during the gravimetric sorting step S140, is more efficient than a simple screening (sieving) operation for sorting the aggregates according to their bitumen content. Indeed, even if the bitumen content is generally higher on small diameter aggregates, there are, however, larger aggregates which also have a high bitumen content. These latter aggregates cannot be identified by the screening operation; the operation of sorting by density, or gravimetric sorting, is therefore necessary to detect these aggregates and integrate them into a batch of asphalt aggregates with a low density, and therefore with a high bituminous binder content. By taking these aggregates into account, it is possible to optimize the recovery of road waste and thus reduce the cost of asphalt.

[0036] The present disclosure also relates to a unit for processing bituminous road waste, comprising a crushing installation capable of crushing road waste, and a gravimetric separator capable, from the crushed road waste, of producing batches of aggregates for bituminous coating, the aggregates for bituminous coating of each batch of said batches produced having a density less than a predetermined maximum density for the batch and / or greater than a predetermined minimum density for the batch.

[0037] The present disclosure also relates to a unit for manufacturing bituminous coating, comprising a gravimetric separator capable of producing batches of aggregates for bituminous coating, the aggregates for bituminous coating of each batch of said batches produced having a density less than a predetermined maximum density for the batch and / or greater than a predetermined minimum density for the batch, and a mixing unit capable of manufacturing a bituminous coating incorporating at least one of said batches produced.

[0038] Finally, by extension, the present disclosure also relates to a road coating manufactured by the bituminous coating manufacturing process presented above, as well as a road comprising a bituminous coating thus manufactured. Brief description of the drawings

[0039] The invention will be better understood and its advantages will appear better on reading the detailed description which follows, of embodiments shown as non-limiting examples. The description refers to the appended drawings, in which:

[0040] [Fig. 1] [Fig. 1] is a block diagram showing the process steps according to the present disclosure;

[0041] [Fig.2] [Fig.2] is a schematic view showing the steps of processing bituminous road waste according to the present disclosure;

[0042] [Fig.3] [Fig.3] is a schematic view of a bituminous coating manufacturing unit according to the present disclosure;

[0043] [Fig.4] [Fig.4] is a graph showing the relationship between the density of asphalt aggregates and their bitumen content; and

[0044] [Fig.5] [Fig.5] is a schematic representation of the stages of stripping a road and reconstructing the road surface.

[0045] Description of embodiments

[0046] An exemplary embodiment of the present disclosure will now be presented in relation to Figures 1 to 5. This example illustrates a method of treating road waste, a method of manufacturing bituminous coating, a road waste treatment unit and a bituminous coating manufacturing unit in accordance with the present disclosure.

[0047] The method for treating road waste aims to prepare one or more batches of aggregates for bituminous coating. Such batches are batches (quantities of aggregates) which can be used during the manufacture of a road coating.

[0048] This method is implemented using a road waste treatment unit 100A shown in [Fig.2]. This unit 100A and a bituminous coating manufacturing unit 100B ([Fig.3]) are two units of the same coating unit or plant 100.

[0049] The road waste treatment unit 100A comprises a crushing installation K, screens S, a gravimetric separator G, and different containers for storing road waste and aggregates at the different stages of the road waste treatment process.

[0050] In the proposed example, the method for treating road waste comprises a crushing step S120 and a screening step S130. It further comprises an initial step SI 10 in which road waste is provided. This waste most often comes from road reconstruction operations, in which, initially, the road surface is destroyed and recovered, which therefore constitutes road waste.

[0051] The method can be optimized by taking into account the maximum diameter of the natural aggregates (sand and gravel) present in the road waste thus collected, for example usually 14 mm or 20 mm.

[0052] The method of treating road waste comprises the following steps (Figs.1,2,5):

[0053] SI 10) road waste is provided. This step is generally carried out by destroying the surface C of a road RI using a bulldozer B (Figs.2,5). The road waste D thus obtained is transported by a truck T to the road waste treatment unit 100A.

[0054] S120) the road waste is crushed in the crushing plant K. This crushing operation produces crushed waste DK which are aggregates, generally of relatively small diameter (less than 20 mm). These aggregates are made up of natural aggregates (sand, gravel), aggregated by a binder, normally bitumen. These aggregates can therefore be used to be incorporated into other components so as to produce a bituminous coating; they are therefore aggregates for bituminous coating.

[0055] S130) The road waste DK thus crushed is sorted by screening using one or more sieves S. Several batches of aggregates for road surfacing are thus formed.

[0056] Depending on the origin of the waste supplied in step S110, it may or may not be necessary to proceed to step S120 of crushing this waste.

[0057] For the screening operation S130, a maximum permitted diameter Dmax is defined beforehand, which is defined as a function of the maximum diameter Dmax_nat of the natural aggregates present in the road waste. For example, the maximum permitted diameter Dmax may be equal to the maximum diameter Dmax_nat of these natural aggregates. In addition, since the method includes a step of separation by gravimetric sorting, a minimum permitted diameter Dmin is also defined, which is the minimum diameter of aggregates that the gravimetric sorting installation is capable of sorting correctly.

[0058] In step S130, in the embodiment presented, the aggregates are separated into a batch L1 of aggregates with a diameter less than Dmin, a batch L2 of aggregates with a diameter between Dmin and Dmax, and a batch L3 of aggregates with a diameter greater than Dmax.

[0059] The aggregates of batch L3, which at the end of the crushing operation have a diameter greater than the maximum permitted diameter Dmax, are returned to the crushing installation K to undergo the crushing operation S120 again.

[0060] When it is known in which bituminous coating manufacturing installation(s) the batches of aggregates obtained by the road waste treatment method will be used, the diameter Dmax is chosen to be less than the maximum aggregate diameter which can be accepted at the input of this or these installations.

[0061] Thanks to this precaution, the screening operation S130 completed by the return to the crushing step S120 of the aggregates with a diameter greater than Dmax makes it possible to guarantee that the maximum diameter of the aggregates obtained by the present waste treatment method is less than the maximum diameter of the aggregates acceptable by the bituminous coating manufacturing installation(s) in which the aggregates will be recycled.

[0062] The aggregates of batch L2, sorted during the screening step S130, which have a diameter greater than the minimum permitted diameter Dmin and less than the maximum permitted diameter Dmax are subjected to a gravimetric sorting operation S140, carried out in the gravimetric separator G.

[0063] By this operation S140, the aggregates are separated into several batches according to their density. In the present example, reference density values ​​pi, i=1,2 regularly distributed have been defined in order to divide the aggregates into several batches. For each of these batches, the density of the aggregates is correlated with its bitumen content; in general, the higher the bitumen content of an aggregate, the lower its density. Consequently, gravimetric sorting of the aggregates makes it possible to sort the aggregates substantially according to their bitumen content.

[0064] In each batch prepared in step S140, the aggregates of the batch are therefore characterized by a density lower than a predetermined maximum density for the batch and / or higher than a predetermined minimum density for the batch. Thus, the first batch L21 groups together all the aggregates with a density lower than p 1; the second batch L22 groups together all the aggregates with a density greater than pl and less than p2; the third batch L23 groups together all the aggregates with a density greater than p2.

[0065] The gravimetric sorting operation can be carried out using a water, aqueous suspension or air gravimetric separator G.

[0066] In the case of an air gravimetric separator, a separator such as the Allair separator (registered trademark) from the company Hazemag, can be used. The technology of gravimetric sorting and air separators, used in another field, namely that of recycling demolition materials containing concrete, is also presented by the document:

[0067] Hoffmann Sampaio C, Cazacliu BG, Ambrôs WM, et al. Demolished concrete recycling by the use of pneumatic jigs. Waste Management & Research. 2020;38(4):392-399. doi:10.1177 / 0734242X20902835.

[0068] At the end of the gravimetric sorting operation S140, the different batches L21, L22 and L23 obtained are stored (step S150).

[0069] Furthermore, the aggregates of batch L1 obtained at the end of the screening operation and whose diameter is less than Dmin are directly stored (step S150), and are therefore not subjected to the gravimetric sorting operation S140.

[0070] The road waste treatment method presented above makes it possible to obtain different batches of aggregates. These batches have different characteristics, depending on the diameter of the aggregates, but also (for aggregates that have been subjected to gravimetric sorting) also on their density. These batches can then be used for the manufacture of bituminous coatings.

[0071] A method of manufacturing bituminous coating using such batches, in accordance with the present disclosure, will now be presented ([Fig.l]).

[0072] This method is implemented in the bituminous coating manufacturing unit (or coating unit) 100B shown in [Fig.3].

[0073] This unit 100B comprises the gravimetric separator G already presented, a storage 10 of batches of aggregates, a storage of bitumen 20, a storage of fine aggregates 30, a storage of natural aggregates 40, a first rotary kiln 50, a second rotary kiln 60, a mixing unit 70, a loading installation 80, a bag filter 90.

[0074] In the present example, the road waste treatment unit 100A and the bituminous coating manufacturing unit 100B are part of the same coating plant 100; the gravimetric separator G is part of both units 100A and 100B. In other embodiments, the road waste treatment unit 100A and the bituminous coating manufacturing unit 100B are completely separate, and for example are not on the same site.

[0075] In the example presented, storage 10 contains batches L21, L22 and L23 obtained at the end of the waste treatment process presented previously, and two other batches of aggregates for bituminous coating L41 and L42, also obtained from road waste. Batches L21, L22 and L23 are directly stored in storage 10 at the outlet of the gravimetric separator G.

[0076] The bitumen storage 20 contains three batches of bitumen L20 having different characteristics; the storage 30 contains different batches of fine aggregates L30; and the storage 40 contains different batches of natural aggregates L40.

[0077] The method of manufacturing road asphalt mainly comprises the following step:

[0078] S200) the bituminous coating is manufactured by mixing a plurality of components including at least one batch of aggregates for bituminous coating, this (these) batch(es) being such that the aggregates of this (these) batch(es) have a density lower than a maximum density predetermined for the batch and / or higher than a minimum density predetermined for the batch.

[0079] In the coating unit 100, these batches are therefore the batches obtained at the end of the road waste treatment process presented previously, and more precisely at the end of the gravimetric sorting step S140.

[0080] The manufacturing step S200 is carried out in the bituminous coating manufacturing unit 100B. In the implementation method presented, it comprises the following steps:

[0081] S210) a formulation is determined for the bituminous coating to be manufactured (The formulation is most often prepared in advance). This formulation includes the proportions of each of the components used for the manufacture of the asphalt mix, namely natural aggregates (generally gravel); fines; bitumen; and at least one batch of aggregates for bituminous asphalt mix, this batch being such that the aggregates in this batch have a density lower than a maximum density predetermined for the batch and / or higher than a minimum density predetermined for the batch.

[0082] The formulation is determined so as to take into account the density or densities (pi) of the batch or batches of bituminous coating aggregates from road waste, for which the maximum value and / or the minimum value (pi) of the density of the aggregates is available.

[0083] S220) the components indicated in the formulation thus determined are provided: The aggregates for bituminous coating, bitumen, fine aggregates, natural aggregates are stored in storages 10, 20, 30 and 40 respectively.

[0084] S230) the components provided for by the formulation for the manufacture of bituminous coating, so that the coating is manufactured in accordance with the chosen formulation.

[0085] In the coating unit shown in [Fig.3], operation S230 is carried out in three main stages.

[0086] First, the aggregates from the different batches of aggregates selected for the manufacture of the asphalt are transported on a conveyor into the first rotary kiln 50. In the kiln, they are both heated and mixed. The mixture thus obtained (first mixture M1) is then transferred into the second rotary kiln 60.

[0087] In the second rotary kiln 60, natural aggregates from storage 40 are added to the first mixture M1, in accordance with the chosen formulation. A second mixture M2 is obtained, which is then transferred to the mixing unit 70.

[0088] In the mixing unit, bitumen and optionally, depending on the formulation, one or more additives are added to the second mixture; the M3 bituminous coating is then obtained.

[0089] The M3 mix is ​​pumped to the loading installation 80, in which it is loaded into the T2 truck tanks.

[0090] The T2 trucks then transport the M3 coating to the place of use.

[0091] [Fig.5] shows for example the construction of an R2 road using M3 coating, using R finishers.

[0092] Advantageously, the manufacture of the M3 coating can be optimized thanks to the information available on the density, and therefore on the bitumen content, of the batches of aggregates from road waste and which are used in the formulation of the coating manufactured.

[0093] This information makes it possible to improve the production of the coating in several ways.

[0094] First of all, naturally the formulation itself can be optimized. A better knowledge of the bitumen content of batches of aggregates for bituminous coating makes it possible to optimize the bitumen content of the bituminous coating. The relationship between the density of the aggregates and their bitumen content is illustrated by [Fig.4],

[0095] This figure represents a reference whose abscissa axis represents the bitumen content X of aggregates, in the form of a percentage, and whose ordinate axis represents the density of these same aggregates. Measurements were carried out on different batches of aggregates; the result of each of these measurements is shown in the figure in the form of a point. It can be seen that the density p of the aggregates is substantially an affine function of their bitumen content X.

[0096] Based on this equation, knowing the desired bitumen content for the asphalt to be manufactured, the choice of batches of aggregates for bituminous asphalt to be included in the formulation of the asphalt can be optimized, and likewise the proportion of aggregates from these different batches can itself be optimized. For example, in the formulation, the proportion of a batch of aggregates for road surfacing can be determined based on the maximum and / or minimum density of the aggregates in that batch.

[0097] In addition, the information available on the density of the batches of aggregates from road waste used makes it possible to better understand the composition of the mixture M1 and of the mixture M2. This information therefore makes it possible, if necessary, to optimize one or more parameters of the coating unit 100, such as, for example, the heating power required in the ovens 50 and / or 60, the residence time of the products in the oven, the rotation speed of this / these oven(s), etc. The value(s) of this / these parameter(s) are then determined as a function of the information available on the density(s) of the aggregates of the batch(es) of aggregates for bituminous coating used for the manufacture of the coating.

[0098] During the mixing step S230, in certain embodiments at least one additive is injected (for example, a rejuvenator), and at least one parameter relating to the injection of additive, for example the proportion of additive, the nature of the additive, etc., is determined as a function of the minimum and / or maximum density of aggregates of batches of aggregates for bituminous coating for which this information is available.

[0099] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made therefrom without departing from the general scope of the disclosure. Furthermore, individual features of the various embodiments discussed may be combined in additional embodiments. Therefore, the description and drawings are to be considered in an illustrative rather than a restrictive sense.

Claims

Claims

1. A method for treating bituminous road waste, comprising the following step: S140) by gravimetric sorting of the road waste, at least one batch of aggregates for bituminous coating is produced, the aggregates for bituminous coating of each batch of said at least one batch having a density less than a predetermined maximum density for the batch and / or greater than a predetermined minimum density for the batch.

2. Method for treating bituminous road waste according to claim 1, wherein in step S140, the gravimetric sorting is carried out using a water, aqueous suspension or air gravimetric separator.

3. A method for treating bituminous road waste according to claim 1 or 2, further comprising the steps: S110) providing bituminous road waste; S120) crushing the bituminous road waste; and a maximum permitted diameter (Dmax) being defined as a function of a maximum diameter (Dmax_nat) of the natural aggregates present in said road waste, S130) by screening said road waste, after the crushing step, separating aggregates with a diameter smaller than the maximum permitted diameter (Dmax) from aggregates with a diameter larger than the maximum permitted diameter (Dmax); and wherein the gravimetric sorting step S140 is carried out only for aggregates with a diameter smaller than said maximum permitted diameter (Dmax).

4. A method of manufacturing bituminous mix from bituminous road waste treated by the method of treating bituminous road waste according to one of claims 1 to 3, comprising the following step: S200) the bituminous mix is ​​manufactured by mixing a plurality of components including at least one batch of aggregates for bituminous mix, the aggregates for bituminous mix of each batch of said at least one batch having a density less than a predetermined maximum density for the batch and / or greater than a predetermined minimum density for the batch and having been produced by step S140 of gravimetric sorting of the road waste.

5. Method for manufacturing bituminous coating according to claim 4, of which at least one parameter of a machine used in manufacturing step S200 is determined as a function of the maximum and / or minimum density of the aggregates of said at least one batch of aggregates for bituminous coating.

6. A method of manufacturing bituminous coating according to claim 4 or 5, wherein the manufacturing step S200 comprises a sub-step: S210) a formulation of the bituminous coating is obtained, the formulation taking into account the maximum and / or minimum density of the aggregates of said at least one batch of aggregates for bituminous coating; and in step S200, the bituminous coating is manufactured in accordance with said formulation.

7. A method of manufacturing bituminous coating according to any one of claims 4 to 6, wherein the manufacturing step S200 comprises a sub-step: S230) heating is carried out on a mixture (M2) comprising at least one heated batch among said at least one batch of aggregates for bituminous coating; and at least one heating parameter of said mixture, for example the heating temperature or a residence time in an oven (50, 60), is determined as a function of the maximum and / or minimum density of the aggregates of said at least one heated batch.

8. A method of manufacturing bituminous coating according to any one of claims 4 to 7, wherein during the manufacturing step S200, at least one additive is injected, and at least one parameter relating to the injection of additive, for example the proportion of additive, the nature of additive, etc., is determined as a function of the maximum and / or minimum density of the aggregates of at least one batch among said at least one batch of aggregates for bituminous coating.

9. Unit (100) for processing bituminous road waste, comprising a crushing installation (K) capable of crushing road waste, and a gravimetric separator (G) capable, from the crushed road waste, of producing batches (L21, L22, L23) of aggregates for bituminous coating, the aggregates for bituminous coating of each batch of said produced batches (L21, L22, L23) having a density lower than a predetermined maximum density for the batch and / or greater than a predetermined minimum density for the batch.

10. Unit (100) for manufacturing bituminous coating, comprising a gravimetric separator (G) capable of producing batches (L21, L22, L23) of aggregates for bituminous coating, the aggregates for bituminous coating of each batch of said produced batches (L21, L22, L23) having a density less than a predetermined maximum density for the batch and / or greater than a predetermined minimum density for the batch, and a mixing unit (70) capable of manufacturing a bituminous coating incorporating at least one of said produced batches.

Images