FR2833627A1 - Application of soil mortar into a cavity, e.g. a hole in a road or a pavement, involves meting and mixing soil mortar and a setting and hardening accelerator in an endless screw conveyor, and pouring the mixture into a cavity - Google Patents

Abstract

Soil mortar and a setting and hardening accelerator are mixed in an endless screw conveyor (13), and the obtained mixture is poured by gravity through a loading chute (14, 28, 30) into a cavity (8) Filling a cavity (8) in, e.g., a road or pavement with soil mortar involves adding at least one setting and hardening additive to the soil mortar, and discharging the soil mortar from a vehicle that conveys the treated soil mortar to the vicinity of the cavity. The process involves: forming a first material comprising the soil mortar and moving it towards the cavity; forming a second material comprising the setting and hardening accelerator and moving it in the direction of the first material; mixing the first and second materials to obtain a third material; and introducing the third material into the cavity (8) by gravity. The amount of the second material is a function of the amount of first material in order to adjust the proportion of the setting and hardening accelerator in the third material. The soil mortar is based on Portland cement, and the accelerator is based on calcium aluminates. The Portland cement does not contain mineral additives such as fly ash or filler. The setting and hardening accelerator includes at most 1% C12A7, and is in the form of a powder, or a grouting liquid containing hardening inhibitors and, optionally, dispersants. Preferably, the cement comprises around 100 kg/m<3> cement, a water/cement ratio of around 2, solely sand whose granulometry is at most 4 mm, and an air-entraining additive that provides an air content of around 15-25% of the total volume. The fluidity of the third material is high enough to allow the mixture of the soil mortar and the setting and hardening additive to be self-coating, i.e. it flows freely into the cavity (8) and fills it completely without leaving significant voids. An Independent claim is given for an installation for implementing the invented process.

Description

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The present invention relates to a method and a device for filling cavities, such as holes or trenches, in particular in infrastructure works, such as street or road pavement, sidewalks, etc.

We know that the maintenance work of such infrastructure works or the maintenance and construction of networks of electric cables, gas or water pipes, etc., buried under these works, require the digging of cavities, annoying for the users of these works. Also, it is essential to quickly fill these cavities, so that said structures can be put back into service as quickly as possible after the end of said work.

For this purpose, it has already been thought to fill these cavities with an ultra-rapid setting mortar making it possible, for example, to put a roadway back into service no more than two hours after the end of this work. To do this, we bring, by transport vehicles of the mixer truck type, a ready-to-use cement-based mortar manufactured in a specialized factory, generally called a concrete batching plant, and we add, in said mixer , a setting and hardening accelerator of said mortar, in powder form and generally based on calcium aluminates, before using said mortar to fill said cavities. However, this process has many drawbacks: - from the point of view of work safety: an operator must climb at the back of the mixer truck, up to the mouth of the said router, carrying bags of the accelerator product of setting and hardening, weighing 25 kg or even 50 kg, he must open said bags and empty the contents

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in the spinning top. This results in a risk of falling and exposure to accelerator dust; from the point of view of the uniformity of the mortar: the setting and hardening accelerator added to a full load of mortar filling the tower cannot mix satisfactorily with the latter during the rotation of the said top , so that the effect of accelerating setting and hardening is not uniform over the entire mortar load. To remedy such a defect, it is possible not to fill the top to the full load of mortar, but then this results in a significant additional logistical cost; - from the point of view of the rapidity of setting and hardening of the mortar: the setting and hardening of a cement mortar, accelerated by a calcium aluminate, are very rapid and depend on the proportions and the nature of the cement and temperature. Consequently, if the emptying of the top cannot be carried out immediately and quickly, the mortar risks hardening in said top, rendering it unusable. In addition, if the emptying of the router is immediate and rapid, but if the use of the mortar cannot be instantaneous, for example due to the nature of the filling process, the mortar hardens before it can be used. to fill the cavities. The latter case occurs in particular when a plurality of small individual cavities or else narrow cavities, such as a narrow-width trench, must be filled; from the point of view of the clogging of the router: after emptying the router, a layer of mortar still remains which adheres to the internal blades of the router. This layer of mortar hardens before the router truck is returned to the plant and can be cleaned and a new layer will be added on the next delivery. Router fouling can become excessive within a single day of delivery and require jackhammer cleaning;

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- du point de vue de la contamination de la charge de la toupie : si le ca- mion-toupie n'est pas soigneusement nettoyé avant d'être chargé à nouveau, le mortier restant peut avoir un effet accélérateur indésirable sur la nouvelle charge de mortier ; et - du point de vue de l'exécution d'un chantier : puisque la prise et le dur- cissement du mortier sont très rapides après l'addition de l'accélérateur, on ne peut introduire celui-ci dans la toupie, que lorsque le camion est en place, prêt à décharger. Mais alors, comme l'introduction de l'accélé- rateur dans la toupie et le malaxage du mortier et de l'accélérateur par la rotation de ladite toupie prend plusieurs minutes, il en résulte un délai d'attente incompressible pour tous les opérateurs, avec interruption momentanée du chantier.

- from the point of view of the contamination of the router load: if the router truck is not thoroughly cleaned before being loaded again, the remaining mortar may have an undesirable accelerating effect on the new load. mortar; and - from the point of view of the execution of a building site: since the setting and the hardening of the mortar are very fast after the addition of the accelerator, it is not possible to introduce this one into the spindle moulder, when the truck is in place, ready to unload. But then, as the introduction of the accelerator into the router and the mixing of the mortar and the accelerator by the rotation of the said router takes several minutes, this results in an incompressible waiting period for all the operators, with temporary interruption of the site.

The object of the present invention is to remedy all these drawbacks.

To this end, according to the invention, the process for filling a cavity by means of a mortar capable of setting, said mortar having to be added with at least one setting and hardening accelerator and being available at the discharge orifice of a transport vehicle bringing it to the vicinity of said cavity, is remarkable in that: a first flow is formed, consisting of said mortar and moving in the direction of said cavity; - A second flow is formed, consisting of said setting and hardening accelerator and moving in the direction of said first flow; - We merge, by mixing them, said first and second streams into a third stream; and - said third flow is introduced by gravity into said cavity.

Thus, thanks to the present invention, the addition and the continuous mixing of the setting and hardening accelerator with the mortar can be carried out outside the router of the transport vehicle, after de-

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loading the ready-to-use mortar and just before the accelerated setting and hardening mortar is placed in said cavity. All the drawbacks of the prior art mentioned above are thus avoided.

Preferably, in order to obtain a desired setting time and rapidity of hardening for the accelerated mortar filling the cavity, the flow rate of said second flow is adjusted as a function of the flow rate of said first flow to adjust the proportion of setting accelerator and hardening in said third stream.

Excellent results have been obtained when said mortar is based on Portland cement, while the setting and hardening accelerator is based on calcium aluminates. The desired acceleration can also be obtained with other types of accelerators.

Advantageously, Portland cement is of the CEM1 type and its formula does not include mineral additions such as fly ash or filler. However, it is possible to obtain an acceptable result with cements of other types and in the presence of mineral additions.

The effectiveness of the setting and hardening accelerator is a function of its mineralogy and it has been observed that a reduced content of C12A7 (less than 1%) is preferable. The aluminous cement known commercially under the reference LSR 5000 constitutes an excellent setting and hardening accelerator.

This setting and hardening accelerator can be in the form of either a powder or a liquid, for example a grout.

In such a grout, the calcium aluminate particles are found in suspension in water, together with calcium aluminate setting inhibitors and, optionally, dispersants. The inhibitors can be zinc borate, boric acid or citric acid and they are incorporated into the calcium aluminates in proportions varying between 0.1% and 3% of the weight of calcium aluminates. Dispersants can

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be one or the other of those known commercially under the references SPE 9413, PE 56-1 or Premia 150 and used in proportions varying from 0.1% to 3% by weight of calcium aluminates. The setting inhibitors, with or without dispersant, have, in this case, the characteristic of giving very stable suspensions over time allowing their storage and transport over a fairly long period, which can reach several months with the appropriate dosages. Dispersants, which are not essential, provide additional stability and viscosity facilitating handling, in particular by pumping. This type of grout has the advantage, when the grout is mixed with a ready-to-use mortar, of accelerating the setting and hardening of the mixture, the acceleration inhibitor being deactivated by simple contact with the mortar. Portland cement base which deactivates it completely and then allows the desired acceleration of setting and hardening.

For the quality of the mixture and the speed of implementation, it is often preferable that the setting and hardening accelerator is in the form of a grout, rather than in the form of powder.

In the case where it is desirable that, after complete filling and hardening of the mortar, said cavity can optionally be opened again (for example to carry out maintenance operations on cables or pipes which it contains), it is advantageous that said cavity mortar has low compressive strength so that it can be easily removed. To do this, one can use a limited cement dosage, for example of the order of 100 kg 1m3, a water / cement ratio of the order of 2, only sand (maximum grain size 4 mm), and a powerful adjuvant. air entrainer making it possible to obtain an air content of the order of 15% -25% of the total volume.

Furthermore, it is advantageous for the fluidity of said third stream to be sufficiently high - which is achieved with the above formulation.

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above - so that the mixture of mortar and setting and hardening accelerator of which it is made is self-placing, that is to say that it flows freely in said cavity while completely coating the walls with it - and any objects therein - and filling the entire volume of said cavity without leaving significant voids.

Optionally, colored pigments can be added to at least one of said fluxes in order to color the accelerated mortar in the mass. It is thus possible to signal the proximity of an object buried in said cavity.

For the implementation of the method described above, the present invention further relates to a device which is remarkable in that it comprises: a first receptacle for receiving the mortar leaving said discharge orifice of said transport vehicle; - first advance means, supplied with mortar from said first receptacle and forming said first flow; a second receptacle for receiving said setting and hardening accelerator; second advance means, supplied with setting and hardening accelerator from said second receptacle and forming said second flow; - Means for melting and mixing said first and second streams; and third advance means, supplied from said melting and mixing means and forming said third flow of mortar and setting and hardening accelerator, resulting from the melting and mixing of said first and second stream.

In an advantageous embodiment, said first and second advancing means, said melting and mixing means and

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said third advance means are constituted by a single endless screw conveyor. This worm conveyor can be inclined relative to the horizontal, its lower end being supplied with mortar from said first receptacle, its intermediate part being supplied with setting and hardening accelerator from said second receptacle and said third flow of mortar and setting and hardening accelerator exiting from the side of the upper part of said worm conveyor.

It may be advantageous that the device of the invention comprises a third receptacle arranged under the upper part of said worm conveyor and intended to receive said third flow of mortar and of setting and hardening accelerator and that the lower part of said third receptacle is in the form of a chute capable of introducing said third flow of mortar and of setting and hardening accelerator into said cavity.

In order to facilitate the movement of the device of the invention from one cavity to another or along an elongated cavity, the first, second and third receptacles and said worm conveyor can be carried by a frame provided with wheels. . A cavity filling trolley is thus obtained.

Advantageously, in the case where the cavity to be filled is a trench, said wheels are able to bear on the ground on either side of said trench, so that the device according to the invention is then placed astride the latter. The device may, in this case, comprise guide means cooperating with said trench and intended to guide it along the latter.

In addition, there can be provided a plate integral with said frame, capable of acting as a float for the accelerated setting and hardening mortar just introduced into said trench. Such a float can be applied

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dig on the ground on either side of the trench to be flush with the level of said mortar to that of the ground. It can also, as a variant, penetrate inside the trench to provide said mortar with a smooth surface set back from the level of the ground.

For the filling of the trench, the wheeled device can be moved along said trench, said first receptacle being continuously supplied with mortar by said vehicle for transporting the mortar along a road parallel to said trench. In this case, it is advantageous that said wheeled device and said transport vehicle are coupled to a common tractor.

The figures of the appended drawing will make it easier to understand how the invention can be implemented. In these figures, identical references designate similar elements.

FIG. 1 is a perspective view of an exemplary embodiment of the device according to the present invention, specially designed for filling narrow trenches.

Figure 2 is a side elevational view, partially cut away, of the device of Figure 1.

Figure 3 is a rear elevational view of the device of Figures 1 and 2, along the line III-III of Figure 2.

Figure 4 is a top view of the device of Figures 1, 2 and 3.

Figure 5 shows, in enlarged perspective from above, a detail of the device of Figures 1 to 4.

FIG. 6 schematically illustrates an alternative embodiment for the device of FIGS. 1 to 4.

FIG. 7 schematically illustrates, in top view, an example of implementation of the method according to the present invention, for filling a trench using the device of FIGS. 1 to 4.

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The device, according to the present invention and shown in Figures 1 to 4 and 7, is in the form of a carriage 1 comprising an elongated frame 2, provided with a pair of front wheels 3 and a pair of rear wheels 4. In the embodiment shown, the two front wheels 3 are mounted in clevises 5 free to rotate around vertical axes, so that said front wheels 3 are spontaneously orientable (which is particularly advantageous in the application. illustrated in figure 7). On the other hand, the two rear wheels 4 are wedged on their shaft 6, without the possibility of orientation. In addition, as illustrated in phantom in Figure 2, the front wheels 3 and / or the rear wheels 4 are mounted adjustable in height under the action of jacks, such as that designated by the reference 7 in Figures 1 and 2, so that said carriage can occupy either a high displacement position or a low working position.

The carriage 1 is specially designed for the filling of trenches 8 made in the ground 9 and the spacing of the pairs of wheels 3 and 4 is provided so that one wheel of each of the pairs can rest on said ground 9, with a side of said trench 8, the other wheel of each pair resting on the other side of said trench, so that the carriage 1 can be placed astride it, as shown in Figures 1, 3, 4 and 7. At its front part, the carriage 1 is provided with coupling means 10.

On the frame 2 of the carriage 1 are mounted a hopper 11, a tank 12, a worm conveyor 13 and a hopper 14.

The worm conveyor 13 is inclined relative to the horizontal, with its front part lower than its rear part. The screw of this conveyor 13 is driven by a motor 15 arranged in the upper rear part. The hopper 11 is arranged above the lower front part of the worm conveyor 13. It can communicate with the latter by

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through an opening 16 made in its lower part, in correspondence with an opening 17 provided in the casing 18 of the worm conveyor 13. The opening 16 of the hopper 11 can be closed by a door 19, actuated by a mechanism 20.

The reservoir 12 comprises a hopper 21, at the base of which is disposed a screw extractor 22, driven by a motor 23. The extractor 22 is provided with an outlet duct 24 opening into a receptacle 25, disposed above. of said worm conveyor 13 and in communication with the intermediate part of the latter by an opening 26, made in said casing 18.

At its upper part, the worm conveyor 13 comprises a discharge mouth 27, directed downwards and arranged above the hopper 14.

The bottom of the hopper 14 is pierced with an oblong opening 28, delimited laterally by two longitudinal plates 29 and 30, able to penetrate into said trench 8.

The electrical, hydraulic and / or pneumatic energy necessary for the operation of the devices of the carriage 1 is supplied to the latter by cables or conduits 31, only shown in FIG. 1. The operation of the devices of the carriage 1 is controlled from the ta - control panel 32.

The motors 15 and 23 are connected to each other by a control device, shown schematically by a link 33 in FIG. 2.

The carriage 1 further comprises, at its front part, a lug 34 able to penetrate into said trench 8 to guide said carriage when it moves along the latter and, at its rear part, a plate 35 covering said trench. When the carriage 1 is in the upper position (see

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position in mixed dashes in Figure 2), the lug 34 is released from the trench 8.

In Figure 7, there is schematically illustrated in top view, the application of the carriage 1 to the continuous filling of the trench 8. To do this, the carriage 1 is coupled with lateral offset, by a chain 36 attached to its means. coupling 10, at the rear of a tractor 37, which moves in the direction of arrow F parallel to the trench 8 and which is, for example, able to lay a cable 38 inside the trench 8. A ready-to-use mortar transport mixer truck 39 is also hitched to tractor 37, by a drawbar 40. During the advance of tractor 37, router 41 of truck 39 continuously unloads the mortar. it contains in the hopper 11, via a chute 42. As a result, said mortar passes through the openings 16 and 17 and is driven by the worm conveyor 13 in the form of a flow of mortar.

Simultaneously, the setting and hardening accelerator for said mortar, kept in reserve in the hopper 21, is extracted therefrom by the extractor 22 and falls into said receptacle 25. It passes through the opening 26 and it is driven by the worm conveyor 13 in a second stream, which is mixed and merged with said first stream, to form a third accelerated setting and hardening mortar stream, which exits the mouth 27 of the worm conveyor 13 and falls into the hopper 14. From there it passes into the trench 8 through the oblong funnel formed by the opening 28 and the plates 29 and 30.

The accelerated setting and hardening mortar introduced into the trench 8 is floated by the plate 35, in order to obtain a smooth surface 8C for said mortar.

Of course, the rotational speed of the worm conveyor 13 is matched to the forward speed of the tractor 37 so that the trench

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8 is correctly filled with accelerated mortar. Thanks to the control 33, the content of setting and hardening accelerator is kept constant at the desired value, whatever the speed of advance.

In an experimental embodiment in which the top 41 had a capacity of 6m3 of mortar, it was possible to continuously fill trenches 8, 10 to 20 cm wide and 30 to 50 cm deep, at the speed of 40 m per minute.

In the above description, it has been implicitly assumed that the setting and hardening accelerator is in powder form. In the case where said accelerator is a grout, the hopper 21 and the extractor 22, 23 of the reservoir 12 are replaced by a container 43, containing said grout, and by a positive displacement pump 44, controlled by said servo 33 and supplying said conduit outlet 24 in grout (see Figure 6).

Claims (19)

1. Method for filling a cavity (8) by means of a mortar capable of setting, said mortar having to be added with at least one setting and hardening accelerator and being available at the discharge orifice of. a transport vehicle (39) bringing it to the vicinity of said cavity (8), characterized in that: - a first flow is formed, consisting of said mortar and moving in the direction of said cavity (8); - A second flow is formed, consisting of said setting and hardening accelerator and moving in the direction of said first flow; - We merge, by mixing them, said first and second streams into a third stream; and - said third flow is introduced by gravity into said cavity (8). 2. Method according to claim 1, characterized in that the flow rate of said second flow is adjusted as a function of the flow rate of said first flow to adjust the proportion of setting and hardening accelerator in said third flow. 3. Method according to one of claims 1 or 2, characterized in that said mortar is based on Portland cement, while the setting and hardening accelerator is based on calcium aluminates. 4. Method according to claim 3, characterized in that said Portland cement does not include mineral additions, such as fly ash or filler. 5. Method according to one of claims 3 or 4, characterized in that said setting and hardening accelerator has a CizA content? at most equal to 1%. <Desc / Clms Page number 14> 6. Method according to one of claims 1 to 5, characterized in that said setting and hardening accelerator is in the form of a powder. 7. Method according to one of claims 1 to 5, characterized in that said setting and hardening accelerator has the liquid form of a grout, comprising setting inhibitors of said accelerator and, optionally, dispersants. 8. Method according to one of claims 3 to 7, characterized in that said mortar comprises approximately 100 kg / m3 of cement, a water / cement ratio of the order of 2, only sand with a particle size of at most 4. mm and an air-entraining adjuvant making it possible to obtain an air content of the order of 15% to 25% of the total volume. 9. Method according to one of claims 1 to 8, characterized in that the fluidity of said third flow is high enough for the mixture of mortar and setting and hardening accelerator of which it is made is self-placing. , that is to say that it flows freely in said cavity while completely coating the walls and filling the entire volume of said cavity without leaving large voids. 10. Device for implementing the method specified in any one of claims 1 to 9, characterized in that it comprises: - a first receptacle (11) for receiving the mortar leaving said discharge orifice of said transport vehicle (39); - first advance means (13), supplied with mortar from said first receptacle (11) and forming said first flow; - a second receptacle (25) for receiving said setting and hardening accelerator; <Desc / Clms Page number 15> - second advance means (13), supplied with setting and hardening accelerator from said second receptacle (25) and forming said second flow; - means (13) for melting and mixing said first and second streams; and - third advance means (13), supplied from said melting and mixing means and forming said third flow of mortar and setting and hardening accelerator, resulting from the melting and mixing of said first and second flux. 11. Device according to claim 10, characterized in that said first and second advancing means, said melting and mixing means and said third advancing means consist of a single worm conveyor (13). 12. Device according to claim 11, characterized in that said worm conveyor (13) is inclined relative to the horizontal, in that its lower end is supplied with mortar from said first receptacle (11), in that its intermediate part is supplied with setting and hardening accelerator from said second receptacle (25) and in that said third flow of mortar and setting and hardening accelerator exits from the side of the upper part of said conveyor to worm screw (13). 13. Device according to claim 12, characterized in that it comprises a third receptacle (14) disposed under the upper part of said worm conveyor (13) and intended to receive said third flow of mortar and setting accelerator. and hardening and in that the lower part of said third receptacle is shaped as a chute (28,29, 30) capable of introducing said third flow of mortar and setting and hardening accelerator into said cavity (8). <Desc / Clms Page number 16> 14. Device according to one of claims 10 to 13, characterized in that the first, second and optional third receptacles, as well as said first, second and third advance means and said melting and mixing means are carried by a frame (2) provided with wheels (3,4). 15. Device according to claim 14, intended for filling a trench (8) made in the ground (9), characterized in that said wheels (3,4) are able to bear on the ground on both sides. other of said trench (8). 16. Device according to claim 15, characterized in that it comprises means (34) for guiding along said trench. 17. Device according to one of claims 15 or 16, characterized in that it comprises a plate (35) integral with said frame (2) and capable of acting as a float. 18. Method according to one of claims 1 to 9, for filling a cavity in the form of a trench (8) made in the ground (9), said filling being carried out by means of the device (1). of one of claims 14 to 17, characterized in that said device (1) is moved along said trench (8) and in that said first receptacle (11) is continuously supplied with mortar by said transport vehicle (39) along a road parallel to said trench. 19. The method of claim 18, characterized in that said device (1) and said transport vehicle (39) are coupled to a common tractor (37).