PT87020B - PROCESS AND PRODUCTION AND LEAKAGE DEVICE FOR BETUME MASS AND ITS APPLICATION FOR THE REALIZATION OF SURFACE COATINGS - Google Patents

Abstract

The apparatus comprises: a chamber (10) having a face (11) open on the side towards which the spreading is effected, the said face being equipped with at least one grid (12); equipment for simultaneously spraying bitumen and water towards the said grid (12) in order to ensure, in the vicinity of the latter, dispersion of the water in the bitumen, and means for producing, inside the said chamber (10), a current of air passing through the latter and being discharged via the said grid (12). The invention also relates to a process for implementing this apparatus and to a process for producing surface coatings. <IMAGE>

Description

PRODUCTION AND PROCESS PROCESS AND DEVICE

BITUME PASTA LEAKAGE AND ITS APPLICATION

SURFACE COATINGS

The present invention relates to an i

production and pouring of bitumen in the state of foam or spongy mass, to its realization process as well as to its application. application of surface coatings.

The formation of a spongy bitumen mass is a known technique, which consists of injecting a determined amount of: water into the bitumen heated to a high temperature. 'Evaporation of water produces a spongy mass that will be more or less important depending on the quality of the bitumen, the amount of water, the presence or absence of foam-creating products and numerous surrounding factors (temperature, humidity, wind, ...).

The formation of the spongy mass has the essential property of giving the bitumen a low apparent viscosity due to the presence of a dispersed gas phase in the form of fine nozzles and above all a high apparent volume that can reach up to twenty times that of the bitumen in the liquid state. An overexpanded health will have a short life span, that is, its return to the unexpanded state will be rapid. lA little expanded but excessively thin mass will return to an unexpanded, very slow state.

Surface coatings consist of depositing a layer of bitumen on the substrate to be covered, pouring gravel over the bitumen and making the gravel compact.

This process offers a seductive solution to the problems of preserving coatings. However, it is necessary to fix the gravel or inert in the bitumen layer so that the coating does not degrade with the passage of vehicles. As a consequence, the most critical problem in the realization of surface coatings lies in the choice of the viscosity of the binder, which must satisfy two traditional requirements:

ΐ '- on the one hand, it is necessary that the binder has a mist; relatively small at the time of the launch of the gravel or inert to ensure an effective fixation of the inert grains,

- on the other hand, so that the grains are not dragged by the circulation, it is necessary that the binder has a sufficiently high viscosity after cooling, in order to guarantee the grain / soil bond, an appropriate cohesion for the transit.

i It is therefore a question of finding the best compromise in viscosity of the binder that reconciles the requirement for an effective anchoring of the grains with the solidity of its fixation to the soil, assuming well understood that the other parameters that condition the result have been mastered of a coating (fines and water content of the aggregates, state of the substrate, content of the binder, binding-grain affinity, realization).

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I j Until now, to ensure the anchoring of the gravels, the viscosity of the binders is adjusted to different values by means of fluxing agents (coal oils) or fluidizing agents (kerosene), depending on the circulation and climate conditions , which allows to minimize gravel rejections

during the more or less long period of solvent evaporation, during which the gravels are fixed on the sidewalk.

This technique has the drawback of evaporating some 50,000 tons of solvents per year in the atmosphere. In addition, the use of these solvents increases the cost of making the surface coating.

The spongy bitumen mass contributes to a decisive improvement in the performance of surface coatings, solving the problem of gravel fixation! by viscous binders, capable of directly supporting an intense, heavy and fast transit.

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FR-A-2 370 126 relates to a process ¹ for making surface coatings in which a binder in the form of a spongy mass is used. The granules are then poured over a layer of bitumen in the state of spongy mas. This mass is made either by injecting a non-binding gas brought to a temperature higher than the condensing temperature, or by vaporizing a liquid in the binder.

! i li i 'l · In this technique, the foam is obtained by injecting one! gas or liquid in the hot bitumen under pressure, the mixture of which begins to create voids as soon as the ejection nozzles exit, by escaping the gas or by vaporizing the injected liquid. These gaps continue to develop on the application support before they are finally reduced. Controlling the characteristics of these masses becomes very difficult and, above all, their dimensional development and life span (the time it takes to expand to the point of losing the advantages of their structure and behavior).

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The present invention aims to contribute to. a solution to the problems mentioned above and aims, in particular, to improve the characteristics of the spongy masses of be

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tume (life span ...) in such a way that they are thin and stable and that their handling is facilitated. The present invention has a device and a process for the production and casting of bitumen that allows the production of a bitumen foam inside a room and from there pouring it into a bed of the continuous, said foam showing improved characteristics in relation to the foam of the prior art. It also relates to the use of the process and the device according to the invention for making surface coatings.

bitumen production and casting device according to the invention is characterized by the fact that it comprises:

- an enclosure with an open face on the side to which the pouring takes place, with said façade equipped with at least one grid,

- equipment for simultaneous spraying of bitumen and water onto the grid, ensuring that water is dispersed in the bitumen in the vicinity of the grid,

- means for producing an air stream inside said room, said air stream going through said room and leaving through said grid.

A device of this nature is simple to design, manufacture, operate, maintain and repair and can adapt very easily to any bitumen leak ramp, adding only a water circuit and an air circuit.

According to another characteristic of the invention, the sprayed bitumen jets and the sprayed water jets completely crash at least in the immediate proximity of the grid reference, with virtually no impact on the side walls of the enclosure.

the production and casting process according to the invention is characterized by the fact that, inside a room that has an open face on the side to which the casting takes place, said face equipped with at least one grid, is carried out simultaneous spraying of bitumen and water to the said grid, in order to guarantee, in the vicinity of the latter, the dispersion of water in the bitumen and also due to the fact that a current of air is simultaneously produced inside the enclosure, said stream of water. air passing through said enclosure and exiting through said grid.

Finally, the invention applies to the realization of surface coatings, which implies a phase of placing spongy bitumen mas on the substrate to be covered, a phase of pouring gravel on said mass and a phase of conpacting the said gravel. This process, of the type known per se, is characterized by the fact that said dough placement is carried out according to the process previously described.

I Throughout the entire text of this description and the claims, the word bitumen also designates bitumen incorporating additives. These additives are well known to those skilled in the art; these are essentially surfactants that favor the formation of voids and that give the bitumen a better grip. Obviously, these additives do not include fluidizers and fluxants that are intended to be eliminated. The water may also contain, in certain cases, fixing or adhesion agents.

Other features and advantages of the present invention can be deduced from reading the description that will follow, made with reference to the attached drawings in which:

figure 1 represents a cross-sectional view of a device according to the present invention,

- figure 2 represents, very schematically, in longitudinal and transversal section, an example of area f

use of a variant of the device of the present invention,

figure 3 shows a second example of a variant of the device of the present invention, in longitudinal and transverse section,

figure 4 shows an example of a preferred embodiment of the device of the present invention, in longitudinal and transverse section, and

figure 5 is a top view of the device in figure 4.

With reference to figure 1, a cross-sectional view of a device according to the present invention is shown.

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This device comprises a container 10 which can be fixed by any classical means to a vehicle intended for pouring bitumen. This container, in a substantially parallelepiped form, comprises an open base 11, equipped with at least one grid. In the particular embodiment of figure 1, the open base 11 comprises two parallel grids 12 and 12 ', spaced apart by a distance of approximately 15 mm or less.

The container 10 is further equipped with a plurality of bitumen spray nozzles 13, of which only one is visible here. These nozzles 13 are oriented along the axis 14 of the cross section of the container 10, perpendicular to the sinks in the grids 12 and 12 '. These nozzles are connected to a liquid bitumen supply circuit of the known type which is not shown here.

The container 10 also has water spray nozzles 15 coupled to a circuit independent of the bitumen supply circuit. The axis 16 of the water spray nozzle 15 advantageously may be offset angularly with respect to the axis of the bitumen spray nozzle in an angle6

it less than or equal to 15q. The choice of the particular nature and the regulation of the spray nozzles 13 and 15 allow conical or lamelliform jets to be obtained, which are totally at the level of the grid 12, without meeting the side faces of the container 10.

The container 10 also includes means (not shown here) that are intended to produce an air stream inside it. They consist, for example, of a fan equipped with heating means connected to a duct that flows into a side face of the container 10; the air stream passes through the container and exits through grids 12 and 12 *.

I 'Always referring to figure 1, the operation of the device is as follows.

hot bitumen and water at room temperature, both under pressure, are projected simultaneously on the grid 12 by the nozzles 13 and 15, respectively. Its impact on the grid 12 causes the spraying of bitumen and water, allowing the formation of a spongy bitumen mass.

ΐ A forced hot air current pushes this mass out of room 10, through grids 12 and 12 '.

By choosing bitumen and its additives, regulating the bitumen flow rates and temperatures of water and air, as well as dimensioning the mesh of the grid (or grids), and the evacuation hopper is able to make a continuous layer of spongy bitumen put out over the entire length of the container.

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The regulation of the displacement speed of the device allows the leakage of this layer on the cover.

At the end of using the device, it is desirable to circulate hot air inside the container, while

that the water bitumen feed circuits are closed. In fact, in the course of making the spongy bitumen mass, bitumen accumulates at the level of the grids. The hot air expels that bitumen out of the container and cleans the latter.

Tables I and II, below, give technical characteristics of the masses made thanks to a device such as that described with reference to figure 1. Tests were carried out with a bitumen spray nozzle equipped with a GIESLER ^R type jet.

The characteristics of the container are as follows:

- Distance between the bitumen spray nozzle / first grid: '73 .mm

- Angle in the vertex of the bitumen jet under 4.6x10 Pa: 50s

- Transverse dimension of the grids: 68 mm j- Mesh opening: 2 and 3 mm

TABLE ί

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With water with additives and pure bitumen '

- bitumen flow: 30 1 / min.

- water flow: 36 1 / h

- air flow: 16 m / h

- bitumen pressure: 4,6.10 Pa

Test No. Mesh opening mm Distance between nm grids Bitumen weight removed kg Expansion rate E * Lifetime ** (s) 1 2 15 1,270 6.50 40 2 2 10 1,385 6.81 42 3 2 0 1,375 7.03 44 4 3 15 2,090 3.16 100 5 3 10 1,460 5.52 74 6 3 0 1,787 4.9 80

* The expansion rate is the ratio of the volume occupied by the spongy bitumen mass to the volume of bitumen before foaming.

** the life span of the spongy bitumen mass corresponds to the time that elapses between the moment when the foam is formed and the moment when the bitumen returns to the liquid state again.

TABLE

II

With bitumen with additives and water with additives

- bitumen flow: 12 1 / min.

- water flow: 14.4 1 / h

- air flow: 6.4 m / h

- bitumen pressure: 5.6.10 ^ Pa

Test No. Mesh opening mm Distance between grids mn Bitumen weight removed kg Expansion rate E * Lifetime ** (s) 7 2 15 2,267 5.09 140 8 2 10 2,524 4.29 214 9 2 0 1,475 7.19 124 10 3 15 2,100 5.95 170 1 1 3 10 1,792 6.45 154 12 3 0 1,653 7.27 130 13, without water - 0 1,769 there is no foaming

| * The expansion rate is the ratio of the volume occupied by the spongy bitumen to the volume of bitumen before

I [foaming.

ί ** The life span of the spongy bitumen mass corresponds to the time that elapses between the moment when the foam is formed and the moment when the bitumen returns to the liquid state again.

By reading in Tables I and II, it appears that the pres are spray 5,6.10 ⁵ Pa is more favorable than the pulverized rização Pa and 4,6.10 the place of the thinner mass and a more homogeneous structure ; this finding is not valid, however, except for conical jets.

In operation with 5.6.10 ⁵ Pa, it is clear that the grids having a mesh opening of 3 mm give a better expansion rate than the other grids.

The closer the two grids get together (even if only one is at sea), the more the rate of expansion of the mass increases; but at the same time, its life span is shortened.

ι In practice, it turns out that the dough made with a sieve [theme and grids, having a mesh opening of 3 mm is very thin, very homogeneous and free from large bubbles.

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Figure 2 illustrates, very schematically, in longitudinal and transverse sections, an embodiment of the device according to the invention. The container 20 has 8 conical bitumen spray jets 21 arranged at a distance equal to each other. The water spray nozzles 22 are arranged between the bitumen spray nozzles 21 [in such a way that at the level of the grid 23, the bitumen jets 24 and water jets 25 collide. A side inlet 26 of hot air draws the mass formed through the grid 23. The container 20 is also equipped with a converging double deflector 27 that channels the mass pushed beyond the grid 25 by the flow of

I | air.

Another embodiment is illustrated in Fig. 3. The container 30 holds 8 conical bitumen spray jets 31. However, the water spray nozzles are oriented in the same direction as the bitumen spray nozzles 31 The adjustment of the nozzles 32 is such that

I that a jet of bitumen 33, close to grid 34, is co11 ζ

1 'opened by the two water jets 35 and 35' located on each side of the bitumen jet 33. The container 30 is also equipped with an air inlet 36 and a converging double deflector 37.j i

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Finally, a third embodiment is shown in Figures 4 and 5, respectively, in longitudinal and transversal section and in top view.

The container 40 has several bitumen spray nozzles 41 facing the grid 46. Water spray nozzles 43 are arranged on the side face 44 of the container opposite the air duct 45 and just behind the nozzles 41 in the direction of displacement of the device illustrated by the two sections, in full. The bitumen jets 41 are flat jets, parallel to each other. These jets can be advantageously inclined at an angle of 15 to 203 with respect to the large axis of the device.

I The bitumen outlet pressure can be advantageous! 5 5

I mind, in this particular case, between 2.10 and 4.10 B Pa.

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In order to allow a pouring of bitumen to the length of a variable width, the device of the present invention may include a spraying equipment that consists of a central part and two foldable elongations. The preferred dimensions of these elements are about 2.40 m and 1.00 m respectively. In this case, the container contains three elements that overlap. The interface between two consecutive elements consists of two vertical dividers that have no effect on the continuity of the dough mat.

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The pouring width can also be adjusted by completely stopping one or more jets of bitumen and water. The container is then equipped with vertical shutters. The hydropneumatic or electric control to open and close the jets acts simultaneously on the moving shutters and isolates the leakage area from the rest of the device.

RESUME

The present invention relates to a foam bitumen production and casting device, characterized by the fact that it comprises: an enclosure (10) with an open face (11) on the side to which the casting takes place, said face being equipped with at least one grid (12); a equipment for simultaneous spraying of bitumen and water to the said grid (12) to ensure, in the vicinity of the latter, the dispersion of water in the bitumen and means to produce inside the said enclosure (10) an air stream that attracts the latter comes out and leaves the grid (12).

It also concerns a process for making this device as well as a process for making surface coatings. .

Claims (11)

1â - Foam bitumen production and casting device, characterized by the fact that it comprises: - an enclosure (10, 20, 30, 40) with an open face (11) on the side to which the pouring takes place, said face being equipped at least with a grid (12, 12 ', 23, 34, 46 ), - a equipment for simultaneous spraying of bitumen and water to the said grid (12, 23, 34, 46) to guarantee, in the vicinity of the latter, the dispersion of water in the bitumen, and - means for producing inside the said enclosure (10, 20, 30, 40) an air stream that crosses the latter and leaves the said grid (12, 23, 34, 46). 2a - Foam production and pouring device according to claim 1, characterized by the fact that the sprayed bitumen jets and the sprayed water jets completely hit the wall ^! us in the immediate vicinity of that grid and, practically! without impact on the side walls of the enclosure. i 3a - Foam bitumen production and casting device according to the claim 2, characterized in that said spraying equipment consists of a bitumen feeding ramp and an independent water supply circuit, each of which is provided with at least one spray nozzle against said grid. i 4a - Foam production and casting device in the foam state according to the claim 3, characterized in that said bitumen spray nozzle (13, 21, 31, 41) develops substantially perpendicular to the plane of said grid. 5a - Foam bitumen production and casting device according to claim 4, characterized in that the axis of said water spray nozzle (15, 22, 43) is displaced angularly with respect to said spray nozzle of water bitumen (13, 21, 41) from an angle less than or equal to 15Q. 6a - Foam bitumen production and casting device according to one of claims 1 to 5, characterized in that the means for producing said air flow are made up of a fan connected at least to a duct that emits at least on one side of the enclosure. 7ã - Foamed bitumen production and casting device according to one of claims 1 to 6, characterized in that it has two parallel grids (12, 12 ') close to each other, preferably spaced apart from each other in a distance less than or equal to approximately 15 mm. Foam bitumen production and casting device according to one of claims 3 to 7, characterized in that the pressure at the outlet of said bitumen spray nozzle is at least 2.10% Pa. Foam bitumen production and casting device according to one of claims 1 to 8, characterized in that at least one of the large side faces of said enclosure extends through a deflector. 10ã - Process of production and casting of bitumen in the foam state, characterized by the fact that, inside a room (10, 20, 30, 40) presenting an open face (11) on the side to which the pouring takes place However, said face being equipped with at least one grid (12, 23, 34, 46), the simultaneous spraying of bitumen and water to the said grid will be carried out, in order to guarantee, in the vicinity of the latter, water dispersion. in the bitumen and also due to the fact that a current of air is simultaneously produced inside the said enclosure, said air current passing through said enclosure (10, 20, 30, 40) and exiting through said grid (12, 23, 34, 46). 11a - Application of the production and pouring process according to claim 10 to the realization of surface coatings. The corresponding request was filed in France, under No. 87 03817, _ on March 19, 1987, whose priority it claims.