FR2674904A1 - MIXTURES BASED ON AGGREGATES AND HEAT MELT BINDERS FOR ROAD COVERINGS, AND METHOD OF MANUFACTURE. - Google Patents

Abstract

In one embodiment of the process, a hot mix with a translucent hydrocarbon binder is prepared, it is separated into fragments on a vibrating sheet (1) and these fragments are dropped in rain in a tank (2) filled with cold water. , to obtain a non-cohesive mix that can be stored for an extended period and regains its initial properties after heating.

Description

Mixtures based on aggregates and hot-melt binders for coatings

  roads, and manufacturing process. The invention relates to mixtures suitable for the production of floor coverings for the development of roads, comprising

  at least aggregates and a hot-melt binder.

  This type of mix includes in particular bituminous mixes with

  in which the hot-melt binder is a two-part binder

  miners, and which are obtained by kneading together the aggregates and the binder at a temperature sufficient for the binder to be fluid, then stored, transported and used hot.

  bituminous mixes are used on a large scale, in particular

  for the construction of roads, and are prepared in numerous coating plants spread over the territory so that an application site is always at a distance from the nearest coating plant allowing the transport of the asphalt mix by lorries, if necessary insulated,

  without solidification by cooling.

  In recent years, asphalt mixes with hydro-

  translucent carbonaceous materials, which differ from the bituminous mixes mentioned above by replacing the bituminous binders with binders which are also of petroleum origin but which

  do not contain the carbon rich constituents

  responsible for the black color of bitumens These mixes with translucent binders are used in lower quantities than the mixes with bituminous binders, in particular for the creation of sidewalks, squares, garden paths, schoolyards, islets traffic lanes, and generally

  all kinds of decorative surfaces with or without circulation

  Pigments are frequently introduced there to obtain attractive colors which cannot be produced in the presence of bitumen. The relatively low production volume of binder mixes

  translucent does not justify reserving a network of ins

  coating plants similar to that used for bituminous mixes The same installations are therefore used for the

  production of these two types of asphalt If the production

  prement known as asphalt with translucent binders occupies these installations only for short periods, on the other hand, for

  prevent them from being stained with traces of bitumen, a pre-

  very important fitting and adaptation of the installation are necessary before each manufacturing operation. Indeed, all the organs having been in contact with the bituminous binder must be cleaned (mixer, storage hopper, transfer carriage) and adapt a circuit of special dosage and injection for the translucent hydrocarbon binder, the duration of use

  of this special circuit being further reduced.

  The need for prior cleaning also applies to any transport or application equipment used for both

types of asphalt.

  The use of the same installations for asphalt mixes with bituminous binders and for mixes with translucent binders have the following consequences:

  the manufacture of these must be rigorously planned

  trusted; the normal operation of the coating plant is disrupted, all other manufacturing to be stopped;

  the daily output of the installation is lowered.

  In addition, the production, as required, of small quantities of mixes with translucent binders does not always make it possible to achieve stable operating conditions of the station,

  which implies a fluctuating quality of asphalt.

  The object of the invention is to remedy these drawbacks.

  The invention relates to a method of manufacturing a mixture suitable for producing a floor covering for the development of

  roads, comprising at least aggregates and a hot-melt binder

  ble, in which the binder is brought to a temperature high enough to make it fluid, and it is brought into contact with the aggregates, characterized in that it comprises a step during which the binder is rapidly cooled by forming

  discrete fragments which do not stick together.

  The mixture can be made in advance, in large quantities,

  stored for a long time and transported over large quantities

  tances in the particulate state, and reheated at the time and at the place of its use to form an asphalt very similar to hot asphalt prepared according to the process

classic.

  The process according to the invention is particularly advantageous

  when the binder is a translucent hydrocarbon binder, the increase

  cost ratio which results from cooling and reheating having a moderate impact on the cost price of the mixture which is already relatively high otherwise This makes it possible to have simpler installations, permanently reserved or assigned for long periods of time to manufacture mixtures

  containing translucent hydrocarbon binders.

  Moreover, the process is technically applicable, and may be of interest in appropriate circumstances, with any type of hot-melt binder used for the installation of

roads and the like.

  Likewise, the method is not limited as regards the nature of the aggregates used, which can in particular comprise

  classic mineral aggregates, glass, wood or metals.

  According to one embodiment of the method according to the invention, the binder is poured onto the cold aggregates, the cooling of the binder occurring during its contact with the aggregates and leading to the formation of binder pellets juxtaposed with the aggregates and of which at least the essential part does not adhere to these. Where appropriate, the binder pellets include fine particles of aggregates, and / or pigments mixed with the aggregates. When using the mixture of aggregates and pellets, it is heated by kneading it in order to thin the binder and to bind the aggregates, and the asphalt obtained is spread on a substrate.

to make a coating.

  According to another embodiment of the method, a hot mix is prepared by bringing the hot binder into contact with the aggregates also heated, this mix is separated by mechanical treatment into fragments each comprising at least one particle of aggregates coated with the binder, and these fragments are quickly cooled to prevent them from sticking

between them.

  Advantageously, the mix is separated into fragments by depositing it on a vibrating support, and the fragments are cooled by dropping them in a cold liquid or in a stream of cold gas. When using the mixture obtained according to this second embodiment, the fragments are reheated in order to bond them to each other by the fluidized binder, and the continuous asphalt obtained is spread over a substrate to make a coating, or else it is spread the fragments on a substrate and we heat them to bind them between

  them by the fluidized binder forming a continuous coating.

  The invention also relates to a mixture comprising at least unbound aggregates and a hot-melt binder in the form of discrete pellets, as can be obtained according to the first embodiment of the method according to the invention, as well as a coated non-cohesive when cold, and becoming cohesive by temperature rise, formed of fragments each comprising at least one particle of aggregates coated with a hot-melt binder, such as

  can obtain it according to the second embodiment of the method.

  Other characteristics and advantages of the invention emerge-

  will have examples of embodiment described below without any

  limiting character, and of the attached single figure which represents

  schematically feels a device for the implementation of the

  method according to the invention in its second embodiment.

EXAMPLE 1

  A conventional asphalt mixing plant is used, such as those used for the manufacture of hot or cold bituminous mixes, provided

  special piping for the supply of hydrocarbon binders

  translucent bonés If the station was previously used for the

  production of bituminous mixes, it is properly cleaned.

  The installation is loaded with cold crushed mineral aggregates, onto which a translucent hydrocarbon binder is brought brought to a temperature of 150 to 1600 ° C., at a rate of 4 to 8 parts by weight of binder per 100 parts by weight of Le aggregates. if necessary, these are mixed with 0.5 to 2 parts by weight

pigments.

  On contact with cold aggregates, the binder cools quickly and therefore undergoes quenching, forming pellets which contain

  where appropriate fine particles of aggregates and / or pigments.

  We therefore obtain a mixture formed of these pellets and particles.

  discrete aggregates and, where appropriate, pigments, including residual fine particles, the pellets not sticking

  between them or discrete particles.

  This intimate mixture can be stored for a prolonged period, in bulk or conditioned, for example in bags, without there being any gain in mass, nor segregation of the components, nor aging of the

  binder comparable to that which would be observed in the event of conservation

tion of a hot mix.

  When the time is right, the product is picked up and transported to the site by dump truck. It is then heated and mixed by a

  site heater to be spread in the form of a coating

  ment Pigments can be added if necessary during mixing, especially if the mixture does not already have one, which makes it possible to obtain different colors on request from a

same production batch.

  The final hot mixture and the coating formed therefrom

  these are very similar to a conventionally manufactured hot mix and to the corresponding coating, both in appearance

  only by the mechanical characteristics determined in laboratory

re.

EXAMPLE 2

  A hot mix with binders is prepared by the traditional process

translucent hydrocarbons.

  This asphalt is poured onto a vibrating sheet inclined about 35 o from the horizontal Due to this vibration and

  this tilt, the aggregate particles roll individually-

  Lement on the sheet, each remaining coated with binder Arrived at the lower edge of the sheet, the coated particles fall in rain and are received in a tank 2 filled with cold water In contact with cold water, the binder is suddenly cooled and

  solidified, forming a gangue around each particle of

  gats One thus obtains a non-cohesive mix formed of fragments each comprising at least one particle of aggregates coated with translucent binder These fragments fall on a conveyor belt 3 immersed in the lower part of the tank 2, which transfers them to a bucket elevator 4 partially submerged This rises them out of the water and pours them onto a discharge mat The tank 2 is shared by a vertical partition 6, interrupted at the bottom to allow the conveyor 3 to pass, into two compartments 7 and 8, the lower edge of the sheet 1 being above the compartment 7 and the elevator 4 plunging into the compartment 8 Cold water is continuously introduced through an inlet 9 at the bottom of the compartment 7, and the same quantity of water is evacuated by an outlet 10 at the top of this same compartment It therefore establishes a circulation of cold water from bottom to top in compartment 7, against the flow of the chu te fragments of the mixture. This mixture can be stored and transported under the same conditions as that of Example 1 After reheating, there is a coated material having the same properties as the starting product. This reheating can be carried out before or after placing the mixture on the substrate to be coated, a new

mixing is not necessary.

  The mixtures according to the invention can in particular be produced in winter, a period of low occupancy of the installations,

  be used in other seasons.

Claims (12)

Claims   1. Method for manufacturing a mixture suitable for producing a floor covering for the development of roads, comprising at least aggregates and a hot-melt binder,   process in which the binder is brought to a sufficient temperature   ment high to make it fluid, and it is brought into contact with the aggregates, characterized in that it comprises a stage during which the binder is rapidly cooled by forming   discrete fragments which do not stick together.   2. Method according to claim 1, characterized in that the   binder is a translucent hydrocarbon binder.   3 Method according to one of claims 1 and 2, characterized   by pouring the binder on the cold aggregates, cooling it   sement of the binder occurring during its contact with the aggregates and leading to the formation of binder pellets juxtaposed with the aggregates and of which at least the essential part does not adhere to these.   4. Method according to claim 3, characterized in that the binder pellets include fine particles of aggregates   and / or pigments mixed with the aggregates.   5. Method according to one of claims 3 and 4, characterized   in that the mixture of aggregates and pellets is reheated by kneading it in order to thin the binder and to bind the aggregates, and that the asphalt obtained is spread over a substrate to produce a coating.   6. Method according to one of claims 1 and 2, characterized   in that a hot mix is prepared by bringing the hot binder into contact with the aggregates also heated, that this mix is separated by a mechanical treatment into fragments each comprising at least one particle of aggregates coated with the binder, and that these fragments are suddenly cooled so as to prevent them from stick together.   7. Method according to claim 6, characterized in that the asphalt is separated into fragments by depositing it on a vibrating support.   8 Method according to one of claims 6 and 7, characterized   by cooling the fragments by dropping them in   cold liquid or in a stream of cold gas.   9. Method according to one of claims 6 to 8, characterized in   that the fragments are heated in order to bind them together by the fluidized binder, and that the continuous asphalt obtained is spread over   a substrate for making a coating.   10. Method according to one of claims 6 to 8, characterized   in that the fragments are spread on a substrate and that they are heated to bind them together by the fluidized binder in forming a continuous coating.   11. Mixture comprising at least unbound aggregates and a hot-melt binder in the form of discrete pellets, such as   can be obtained by the method according to one of claims 3   and 4. 12. A non-cohesive cold mix which becomes cohesive by temperature rise, formed of fragments each comprising at least one particle of aggregates coated with a hot-melt binder, such as   can be obtained by the method according to one of claims 6 at 8.