FR2706922A1 - Anti-pollution device for trapping wind-borne cement fines, in particular when using a road reconditioning machine including two chassis moving one after the other - Google Patents

Abstract

Anti-pollution device making it possible to trap wind-borne cement fines, in particular when using a reconditioning machine for a road, including two chassis moving one after the other, namely, on the one hand, a first chassis fitted with a water tank, a cement tank and a cement dispenser (60), in particular of the cavity type, associated with a protective skirt (10) capable of pouring and distributing a layer of cement with controlled thickness over the entire width of the road, and, on the other hand, a second chassis, following the first and capable of engaging at a predetermined height on the cement-covered road in order to fragment it and crush it into aggregrates before homogenising it and mixing it and, finally, redistributing it over the road, which anti-pollution device is characterised in that it includes spray means (12, 13; 18, 19) capable of capturing and/or fixing the cement fines in order to agglomerate them and drop them onto the ground and/or hold them there.

Description

 The present invention relates to an anti-pollution device making it possible to trap fine cement entrained by the wind, in particular during the implementation of a pavement reconditioning workshop comprising two chassis moving one at a time.

following each other.

The very significant development of road traffic, in particular that of heavy vehicles such as trucks, the problems of freezing the road network, etc ..., require a strengthening of the roadways
To this end, reconditioning devices have been developed which make it possible to effectively reinforce pavements for a very long period and this for a limited cost price, considerably lower in most cases than the costs of temporary maintenance work.

 Such a reconditioning device is, by way of example described in document FR-A-85 12 724: it is a device which moves on the pavement to be reconditioned and distributes therein a layer of binder, in particular of cement and water, then attack it to a predetermined thickness to fragment and crush it into aggregates before homogenizing and kneading it and finally redistributing it on the pavement.

 This device consists of a self-towing vehicle comprising in the direction of travel a cement metering device, a milling rotor arranged in a decohesion chamber to attack the roadway to be treated, a calibration grid and a mixing rotor.

 Despite its definite advantages, this machine has not given the expected results in use, in particular because it does not offer sufficient adjustment possibilities for the quantity of cement distributed over the width of the roadway before being put in place. milling rotor work.

 A precise adjustment of this quantity (therefore of the mass of cement distributed per unit of surface) is indeed essential to obtain at the end of treatment a satisfactory reconditioned pavement, that is to say homogeneous, stable, resistant and above all insensitive to gel.

 It is important to note that in this presentation, the term cement must be understood in a very general sense and covers both standardized cements used in civil engineering and slow-setting "road" cements specially developed for road technique or even powdery hydraulic binders such as: ground or ground slag, fly ash from the combustion of coals, ground or ground natural pozzolans and hydraulic lime; similarly the term cement can also include quicklime or slaked lime widely used for the treatment of soils, in earthworks and pavements.

 To overcome this drawback, it has been proposed, in accordance with document FR-A-86 03 362, a pavement reconditioning workshop comprising two chassis moving one after the other, namely, on the one hand, a first chassis provided with a water tank, a cement tank and a cement doser capable of spilling and distributing over the entire width of the roadway a layer of cement of controlled thickness , and, on the other hand, a second chassis following the first one and capable of attacking the pavement covered with cement over a predetermined height to fragment and crush it into aggregates before homogenizing and kneading it and finally redistributing it on the road.

 We have been able to verify, in use, that the "splitting" of the workshop into two separate frames allows better control of the quantity of cement discharged by the cement metering device.

 In such a workshop, this metering device can advantageously be constituted by a drive rotor mounted in a tube and on the periphery of which are welded equidistant longitudinal bars delimiting between them metering cells.

 It has been observed that the implementation of a reconditioning workshop of the aforementioned type in which the two chassis moves at a distance of the order of 5 to 10 meters from each other is not without danger for the environment, in particular for crops, or when the workshop is implemented in urban areas: in fact, the fact of spreading cement on the pavement, and the fact that this (about 30kg / cm2 for 30 cm of treatment) or in the open air between the two machines, in particular in windy weather, the departure of fines (dust) which correspond to a significant source of pollution for the environment.

 To limit this problem, the cement metering device, in particular of the cellular type, cooperates well in a conventional manner, at its rear part in the direction of advancement of the first chassis, with a protective skirt extending over the entire length of the metering device. cement (which corresponds to the width of the pavement to be treated) and extending laterally on either side of it; however, it has been observed that the presence of such a protective skirt does not prevent the flight of fines which can escape through the lower part thereof, in particular laterally.

 The object of the invention is to provide an anti-pollution device capable of remedying these drawbacks by making it possible to trap the fine cement entrained by the wind, in particular during the implementation of a workshop for reconditioning a pavement of the type mentioned above.

 According to the invention, this device is characterized in that it comprises spraying means capable of capturing and / or fixing the cement fines to agglomerate them and cause them to fall on the ground and / or keep them there.

 It has been noted that the main source of pollution corresponds to the flight of fines at the level of the cement metering device, that is to say where the cement is in motion before reaching the pavement to be treated.

 To eliminate this source of pollution, the spraying means comprise, according to an essential characteristic of the invention, a misting ramp equipped with misting nozzles supplied with air and water, mounted inside the protective skirt and extending essentially perpendicular to the axis of the carriageway, over the entire width of the latter so as to send a mist of water such as to capture the cement fines as soon as they leave the metering device.

 This is, in fact, a system comparable to those used in industrial wet dust collectors. Thanks to this system, the fines are immediately agglomerated as soon as they leave the cement dispenser before falling to the ground under the effect of their gravity and being held there.

 The water supplying the misting ramp can advantageously be taken from the water tank provided on the first chassis to send water to the milling rotor of the second chassis to which it is connected by a flexible pipe.

 The air supplying the misting ramp can be taken from a compressor with which the first chassis is also fitted.

 Besides this pollution "at the source", it is necessary to take into consideration the pollution resulting from the presence between the two frames of a layer of dry cement which can, in windy weather, give rise to a significant flight of fines.

 To remedy this second source of pollution, the spraying means comprise, according to another essential characteristic of the invention, a spray boom fitted with spray nozzles supplied with pressurized water and, where appropriate, with air, mounted to the rear part of the protective skirt, in the direction of advancement of the first chassis, and extending essentially perpendicular to the axis of the road over the entire width of the latter, so as to fix the bed cement spread on the roadway by humidification.

 According to the invention, the spray nozzles can advantageously be equipped with diffusers making it possible to send a linear beam of very fine jets in the form of a brush, so as to guarantee a good distribution of the humidity on the floor.

 For this device to function satisfactorily, it is imperative that the nozzles are not likely to be blocked by dust for this reason, and according to another characteristic of the invention, the spray boom cooperates with a filter.

 The water supplying this ramp can, of course, advantageously also be taken from the existing water tank on the first chassis.

 According to another characteristic of the invention, the misting boom and / or the spraying boom cooperate with members for adjusting the height and / or direction.

 The presence of such bodies may indeed prove to be essential in order to obtain a satisfactory elimination of any risk of the flight of fines and of pollution of the environment by them.

 Of course, the example of pavement reconditioning machines should only be considered as an example of implementation of the invention which can also be applied to all machines which spread pulverulent materials, whether in the field of road engineering or other techniques, particularly in the field of agriculture.

The characteristics of the antipollution device which is the subject of the invention will be described in more detail with reference to the accompanying drawings in which - Figure 1 is an overall side view of a
reconditioning workshop for a compliant pavement
to that described in document FR-A-86 03 362, - Figure 2 is a diagram representing the device
anti pollution.

 According to FIG. 1, the reconditioning workshop which is, as a whole, mobile in a direction of advance represented by the arrow A, comprises two chassis 2 and 3 moving at a distance of the order of 5 to 10 meters each other to recondition a pavement 1.

 The role of the chassis 2 is to distribute, with a precise dosage over the entire working width of the roadway 1, a layer 4 of dry cement represented in hatched form and to dose a predetermined quantity of water to inject it into the housing. of the chassis rotor 3 to which it is connected by a flexible pipe 8.

 The role of the second chassis 3 is to attack the pavement 1 coated with the cement layer 4 over a determined height h and to fragment and crush it into aggregates before homogenizing and kneading it and finally redistributing it over the pavement in a layer of predetermined thickness H.

The configuration of the second chassis 3 corresponds to that described in the above-mentioned document
FR-A-86 03 362 and will therefore not be described in detail in this presentation.

 The first chassis 2 comprises a water tank 5, a cement tank 6 cooperating with a cement metering device 60 as well as an air compressor 9 which is shown diagrammatically in FIG. 1.

 The water tank 5 is, of course, connected, in a manner not shown, to the flexible pipe 8 supplying the second chassis 3.

 In a similar manner to that which has been described in the document FR-A-86 03 362, the cement doser 60 whose role is to distribute a predetermined quantity of cement on the layer 4 is constituted by a drive rotor 61 mounted in a tube 62 and carrying on its periphery equidistant longitudinal bars 63 which delimit metering cells between them; the assembly thus constituted is very rigidly constructed to guarantee the volume of the cells.

 It is essential that the tube 62 extends over the entire width of the roadway 1 in order to be able to pour onto it a layer of cement whose characteristics can be perfectly controlled.

 According to Figure 1, the cement metering device 60 also cooperates at its rear part in the direction of advance A of the chassis 2 with a protective skirt 10 whose role is to guide the dry cement flowing through the cells dosing to avoid uncontrolled flow.

 According to FIG. 2, the protective skirt 10 comprises a central branch 11 extending to the rear part of the cement metering device 60, in the direction A of advancement of the first frame 2, over the entire length of the tube 62, and extending laterally by two branches 11 and 11 '.

 To avoid that, in windy weather, in particular in the presence of a crosswind, fines escape from the dry cement distributed by the cement metering device 60 and fly away through the lower part of the skirt 10, according to the arrows a or b, the latter is provided, at its internal part, with a misting ramp 12 extending over the entire length of the tube 62, parallel to the axis xx 'thereof, therefore perpendicular to the direction of movement A of the chassis 2. This misting ramp is equipped with misting nozzles 13 distributed over its entire length and supplied, on the one hand, with water from a pipe 14 connected to the water tank 5 of the first chassis 2 , and, on the other hand, in air from a pipe 15 connected with the compressor 9 of this chassis; the pipe 15 leads to a main air distribution pipe 16 from which leave secondary pipes 17 capable of independently supplying each of the misting nozzles 13. This system, which is largely comparable to known industrial wet dust collectors, makes it possible to send at the outlet of the cement metering device 60, a mist of water capable of capturing the cement fines as soon as they leave the metering device so as to allow them to agglomerate and fall onto the ground under the effect of their gravity; one can thus avoid any uncontrolled escape of fines according to the arrows a and b at the lower part of the skirt 10, in particular at the level of the lateral branches 11, 11 ′ thereof under the action of transverse winds.

 According to FIG. 2, the misting ramp 12 cooperates with a spraying ramp 18 mounted essentially parallel to the latter at the rear part of the protective skirt 10 in the direction of advance A of the first chassis 2. This spraying ramp which also extends over the entire length of the tube 62 is provided with a series of spray nozzles 19 equipped with diffusers not shown in the figure which are supplied with pressurized water via a pipe 20 also connected to the water tank 5, this by means of a filter 21 making it possible to avoid any clogging of the spray nozzles 19 by fines of cement.

 The ramp 18 thus equipped sends, onto the bed of cement 4 which has just been spread over the roadway, a linear beam of very fine jets in the form of a brush which makes it possible to obtain fixing of the cement by humidification until that -this be treated by the second chassis 3 while avoiding any untimely flight of fines likely to pollute the environment.

 Not shown in the figures, it is particularly advantageous to equip the misting boom 12, on the one hand, and the spraying boom 18, on the other hand, with height and direction adjustment members.

Claims (9)

 RESELL I CAT IONS  1 Antipollution device making it possible to trap fine cement entrained by the wind, in particular during the implementation of a pavement reconditioning workshop comprising two chassis moving one after the other, namely, on the one hand, a first frame (2) provided with a water tank (5), a cement tank (6) and a cement metering device (60), in particular of the cellular type, associated with a protective skirt (10) capable of spilling and distributing over the entire width of the roadway (1), a layer of cement (4) of controlled thickness, and on the other hand, a second chassis (3) following the first and likely to attack over a predetermined height (h), the pavement (1) covered with cement (4) to fragment and crush it into aggregates before homogenizing and kneading it and finally redistributing it over the roadway, anti-pollution device characterized in that it comprises spraying means (12, 13; 18, 19) of a nature to capture and / or fix the fines of cement to agglomerate them and make them fall on the ground and / or keep them there.  2 ") anti-pollution device according to claim 1, characterized in that the spraying means comprise a misting ramp (12) equipped with misting nozzles (13) supplied with air and water, mounted inside the skirt of protection (10) and extending essentially perpendicular to the axis of the roadway (1), over the entire width of the latter so as to send a mist of water such as to capture the cement fines to their output from the metering device (60).  3 ") Anti-pollution device according to claim 2, characterized in that the water supplying the misting ramp (12) is taken from the water tank (5).  4 ") anti-pollution device according to any one of claims 2 and 3, characterized in that the first chassis (2) is provided with an air compressor (9) at the level of which the air supplying the misting ramp is taken (12).  5) anti-pollution device according to any one of claims 1 to 4, characterized in that the spraying means comprise a spray boom (18) equipped with spray nozzles (19) supplied with pressurized water and, where appropriate , in air, mounted at the rear part of the protective skirt (10) in the direction of advance (A) of the first chassis (2) and extending essentially perpendicular to the axis of the roadway (1) on the the entire width thereof, so as to fix the bed of cement spilled on the roadway by humidification.  6) anti-pollution device according to claim 5, characterized in that the spray nozzles (19) are equipped with diffusers making it possible to send a linear beam of very fine jets in the form of a brush, such as to guarantee a good distribution of the humidity on the road (1).  7 ") Anti-pollution device according to any one of claims 5 and 6, characterized in that the spray boom cooperates with a filter (21).  8 ") Device according to any one of claims 5 to 7, characterized in that the water supplying the spraying boom (19) is taken from the water tank (5).  9 ") Device according to any one of claims 2 to 8, characterized in that the misting boom (12) and / or the spraying boom (18) cooperate with members for adjusting the height and / or direction.