EP1100663A1

EP1100663A1 - Method and apparatus for adding a liquid additive to a material comprising at least a liquid

Info

Publication number: EP1100663A1
Application number: EP99932965A
Authority: EP
Inventors: José Galeote
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-07-24
Filing date: 1999-07-23
Publication date: 2001-05-23
Also published as: BR9912383A; FR2781392B1; FR2781392A1; WO2000005047A1; AU4916499A; AR021166A1; MXPA01000799A

Abstract

The invention concerns an apparatus (20) comprising: at least a first device (25) for volumetric measurement of the additive based on a predetermined amount of liquid, said device (25) being designed to operate said measurement according to a relatively wide range of additive proportions, for example from 2 to 10 %; at least a second device (24) of similar type, designed to operate said measurement according to a relatively narrow range of additive proportions representing a fraction of additive percentage, ranging from 0.2 to 1.9 %, both said devices (24, 25) being mounted in series; means (26, 27) forming branch connections, for collecting the additive dose determined by one or the other measuring devices (24, 25) and mixing said dose to said amount of liquid downstream of the device (25) located furthest downstream; means (28) for subsequently mixing the amount of liquid containing the additive with other constituents of the material, for forming the latter.

Description

METHOD AND APPARATUS FOR ADDING A LIQUID ADDITIVE TO A MATERIAL COMPRISING AT LEAST ONE LIQUID

The present invention relates to a method and an apparatus for adding one or more additives, liquid or suspended in a liquid, to a multi-component material comprising at least one liquid entering into its composition, this liquid which enters the composition of said material reacting with one or more of the other components of this material, with a view to the implementation of the latter. The invention is particularly applicable, in the field of building or public works, to the addition of additives or adjuvants, in particular one or more dyes, to water which reacts to the components of a material of the mortar, concrete, plaster or plaster type, which combines with a hydraulic binder which this material comprises.

It is well known to color formulations based on hydraulic binders in the factory, this coloring being carried out by mixing the additive or coloring pigment in the dry state with the other constituents of the formulation. In particular, for ready-to-use coatings, these formulations are sold under different coloring references depending on the supply and formulation of the added oxides (pigments). There are therefore as many bags of colored products as there are colors to be produced, and these are then used on construction sites.

In addition, this pre-coloring in the factory poses a certain number of essential practical problems on a site:

- the order of a quantity of material of a certain shade may exceed the needs of the user for this material; the excess quantity is then unused, which results in a loss;

- conversely, the quantity ordered could have been underestimated, which leads to a stoppage of the site for a period which can be relatively long, given the time periods for supplying this type of material.

In practice, the use of exterior plasters, for example, can be carried out by one or other of the following methods:

- mixing the dry colored product prepared in the factory with the quantity of water prescribed by the manufacturer, which poses the problems indicated above, whether or not we use plaster spraying machines; - use of a silo containing bulk material, this silo being equipped with a machine kneading this material and, for certain models, with a spraying machine; in this case, when different colors are necessary on the same site, it would be necessary to have a silo for each color, which is economically impossible.

Another coloring process, tending to replace that above, consists in adding a predetermined dose of coloring product to the mixing water and then mixing a white mortar with this colored water. According to this process, the quantity of coloring product is calculated by proceeding to the ratio between the mass of binder (cement, lime, plaster) that the material comprises and the quantity of water necessary for its mixing. The amount of coloring product, in particular iron oxide, is determined by weighing. Other additives (various additives, accelerators, antifreezes, plasticizers, retarders ...) can be added, by calculating the quantity of these additives in the same way.

There are generally, with pigment pastes, problems of abrasion, and, moreover, this process poses problems of imprecision of the quantity of additive determined by weighing, of deposition of the additive in the water of mixing which is awaiting use, and imprecision of the amount of colored water when mixed with the powder (binder).

Damaging consequences may result, in particular as regards, in the case of a coloring product, the shade of shade obtained.

Other methods for coloring hydraulic materials, already described, for example in GB patents 1,577,321, or GB No. 2,302,817, consist in introducing a dye suspended in water directly into the mortar already spoils. This solution has the disadvantage that the distribution of the dye in the mortar remains random and not homogeneous (in the specific case of these patents, this effect is precisely sought). In addition, these solutions are ill-suited to operating conditions on a building site.

The dosing of additives, automatically, on site, is currently carried out in different ways, for example using electromechanical or hydraulic metering pumps with double diaphragm. These devices are inconvenient to use, for several reasons:

- they operate on electricity, (380 or 220 V), which imposes strict protection standards (class F); - the pump is heavy, especially due to the existence of electric motors (6 kg minimum), and its volume is large, which makes it difficult to handle; in addition, there is a need for special tanks for the location of the pump;

- the desired quantity of additive cannot be adjusted, the pump flow rate being fixed (for example, 3 or 7 or 1 1 or 15 liters per hour) and its precision being only 5% of the volume;

- finally, the cleaning of these pumps is restrictive: part of the pump must be dismantled on site; some models must be rinsed with hydrochloric acid, which induces a risk of accidents, before rinsing with clear water; cleaning must also be carried out twice a day, which adds to the wear of the parts comprising a thread.

Other systems are also used: in particular a volumetric metering system, which must often be accompanied by a membrane pump, which again generates the drawbacks mentioned above; on the other hand, the cylinder of the positive displacement pumps is made of acrylic glass, therefore fragile. This system works well in the laboratory or at a fixed station, but it is unsuitable for use on a construction site. Electronic rocker dosing systems also exist, but they have the same drawbacks as above (need for electricity, reduced maneuverability, etc.), with the additional need for a drain pump.

The present invention aims to remedy all of these essential practical drawbacks, by providing a method for adding one or more additives, liquid or suspended in a liquid, to a material with several components comprising at least one liquid. entering into its composition, as well as an apparatus for the implementation of this process, which make it possible to respond precisely to the needs of their users, in particular with regard to the production of a determined quantity of material of a certain shade , without problems of imprecision of the amount of additive added or of abrasion in the devices used, and which can be used easily on a building site, that is to say without involving constraints of electrical supply, heaviness of the device, limitations as to permitted dosages or cleaning. To this end, the process which it concerns comprises the successive operations consisting of:

- to determine the quantity of liquid entering into the composition of the material;

- passing this quantity of liquid through at least two volumetric metering devices, mounted in series, these devices operating an additive metering and being able to operate independently of one another, one of these devices being provided to operate this dosage according to a relatively wide range of additive proportions, for example from 2 to 10%, while the other device is provided to operate this dosage according to a range of relatively narrow additive proportions, including proportions representing a fraction of a percentage of additive, ranging for example from 0.2 to 1.9%;

- mixing the additive dosed by said devices and said quantity of liquid downstream of the dosing device located furthest downstream, and - combining this quantity of liquid and the additive which has been mixed with it with the other components of the material, for the implementation of the latter.

Thus, it is the liquid itself which receives the additive and which serves as a vehicle for mixing this additive with the other components of the material. The invention therefore makes it possible to eliminate the weighing of the additive and to obtain, in the case of a coloring product, a precise shade of material.

The two dosing devices make it possible to determine a precise quantity of additive. In the event of a proportion of additive remaining in the range permitted by said second device, only this second device is put into operation, while in the case of a proportion of additive exceeding this same range, the first device is also put into operation, these two devices then acting jointly to dose the quantity of additive precisely required. This quantity of additive dosed by one or both devices is not mixed with the liquid in one and / or the other of the devices but is mixed with the liquid downstream of the device located furthest downstream. Thus, the liquid loaded with additive does not pass through the devices, which, in the case of very abrasive additives such as iron oxides generally constituting the coloring products used for coloring materials of the mortar, concrete, plaster or plaster type, eliminates any damage to these devices, in particular their pumping systems. These devices can therefore be of the common type, that is to say of the type of those normally used for metering non-abrasive additives, and the abovementioned cleaning problems are eliminated. The method advantageously includes the operations consisting of:

to obtain the quantity of liquid entering into the composition of the material from a source of liquid under pressure, and

- to use volumetric metering devices operating an additive metering while being actuated by the pressure of said liquid.

This process can thus be implemented without electrical energy. For the implementation of a material of the mortar, concrete, plaster or plaster type, the liquid is water, and the source of liquid under pressure can simply be a pipe connected to the water distribution network.

The method can however be implemented by using metering devices actuated by a source of energy of their own, in particular electrical.

When the material with several components comprising at least one liquid entering into its composition is a material of the mortar, concrete, plaster or coated type, and said liquid is water, the additive is then in particular an iron oxide in suspension in water, which is usually a coloring product used to color such a material. The device includes:

- At least a first volumetric dosing device for an additive, liquid or suspended in a liquid, according to a predetermined quantity of liquid, this device being provided for carrying out this dosing according to a relatively wide range of proportions of additive , ranging for example from 2 to 10%; at least one second device of the same type, provided for carrying out this assay according to a relatively narrow range of proportions of additive, including proportions representing a fraction of percentage of additive, ranging for example from 0.2 to 1.9% , the two aforementioned devices being connected in series;

- means forming bypasses, making it possible to collect the dose of additive determined by one or by the two metering devices and to mix this dose with said quantity of liquid downstream of the device located furthest downstream, and - means for then mix the quantity of liquid thus added with additive to the other constituents of the material, for the implementation of the latter.

To use the device according to the invention, it suffices to introduce the suction pipes for the additive into the container (s) containing this additive, the end of these pipes advantageously comprising strainers, and to put the device Operating. The change of the additive (s) is easy and very fast.

The metering devices are advantageously of the type actuated automatically by the quantity of liquid entering into the composition of the material, which is under pressure and which passes through them.

Said first metering device is preferably that sold by the company DOSATRON INTERNATIONAL (located at TRESSES 33370,

France) under the reference "DI210" and the second is that sold by this same company under the reference "DM 6", the dosage range allowed by this second device having been increased to go, in the upper limit, from 1.6 to 1.9%, by increasing the maximum capacity of the metering chamber of this device.

Extending this range to 1.9% fills the existing range between that allowed by the standard DM 6, whose upper limit is 1.6%, and that allowed by the DI210, the latter starting only at 2%.

Each of these two devices is modified to allow it to dose abrasive additives or not, in particular as mentioned above, these modifications consisting: - in the upper closure of the metering chamber of each device, to isolate this chamber from said liquid which passes through the device, in order to prevent any mixing of this additive and this liquid within the device, and

- By arranging a lateral opening in the wall delimiting this chamber, to allow the ejection of the quantity dosed by each device not in the device but in a pipe located downstream of the two devices.

Each of these two devices can also include one or other of the following modifications:

- the non-return valve located at the bottom of the metering chamber of each device includes a ceramic or stainless steel ball;

- the connection of the additive suction tube is of the quick connection type to avoid air intakes (instead of a conventional connection by thread). These DOSATRON dosing devices

INTERNATIONAL have been selected for their operation without electricity and the proportional volumetric dosage they allow (dose / quantity of liquid). The method according to the invention can however be implemented by means of any other similar volumetric device, provided that the appropriate modifications indicated above are carried out.

In order to decide whether to start or stop the device, an upstream valve for controlling the flow of liquid may be provided; the control handle of this valve can be located in the outer part of a box housing the device, so as to easily reach this handle.

It is also possible to provide, upstream of the metering device located upstream, a filter which makes it possible to ensure the perfect quality of the liquid, in particular of the water, which must operate the metering devices. Indeed, on a construction site, the connection of the pipe to the water distribution network is done through so-called GK fittings (or firefighters' fittings), which, dragging on the ground, contain impurities (sand, etc.) .

It is possible to provide a flow limiter upstream of the metering device located upstream, limiting the flow rate of the liquid so that this flow rate remains below the maximum flow rate that can be supported by the metering devices. The apparatus may also comprise a homogenization device for mixing the dose of additive determined by one or both of the metering devices with the liquid, this homogenization device preferably operating by means of the pressure of the liquid and allowing mixing. of this liquid and the additive before the mixture leaves the device.

A non-return valve can be provided, downstream of the metering devices and upstream of the connection of the additive supply branches, to prevent this additive from entering the metering devices.

If the introduction of the liquid mixed with the additive into the material must not take place continuously (for example, if the material is contained in a tank, in a concrete mixer or in a spraying machine etc.), it is possible to provide a metering valve operating with liquid pressure, which can program the quantity of liquid to be injected. This valve will be positioned at the level of the mains water supply.

An easy-to-use cleaning system can also be installed, for example in the form of a three-way cleaning valve, which includes water outlets fitted with quick couplings of diameters identical to those allowing the connection of the suction pipes. of additive, and a line connected to a cleaning gun.

Cleaning is then carried out as follows: at the end of the work, the flow of liquid is stopped; the strainers are extracted from the containers containing the additive, then the valve is opened to allow the strainers to be cleaned; the latter are separated from the additive suction lines, then the ends of these lines are connected to the cleaning system; a pressurized water flow is then carried out to clean the entire circuit.

The apparatus according to the invention can also be arranged in an at least partially electrically controlled version. In this case, this device includes:

- a turbine crossed by said liquid entering into the composition of the material, this turbine being connected to an electricity generator; - electrically actuated means, fulfilling at least one of the following functions: (i) control of setting on / off operation of each dosing device; (ii) counting the number of operating cycles of each metering device, to make it possible to determine the amount of liquid flowing through each device and, consequently, the amount of additive metered; (iii) control of the modification of the quantity of additive dosed by each device.

For a good understanding, the invention is again described below with reference to the appended diagrammatic drawing representing, by way of nonlimiting example, a preferred embodiment of the apparatus which it concerns.

Figure 1 is a side view, in partial longitudinal section, of a volumetric metering device, the device according to the invention comprising two of these devices, modified; Figure 2 is a side view of the apparatus according to the invention, according to a first version; Figure 3 is a view of a modified metering device, which includes a second version of the device; Figure 4 is a view of two metering devices, modified according to this second version, and Figure 5 is a schematic and very simplified view of the device according to this second version.

FIG. 1 represents a volumetric metering device, of the kind making it possible to meter a product in proportion to a quantity of liquid under pressure, generally water, passing through this device and to add this product to this liquid within this device.

The device shown is one of those manufactured and marketed by the company DOSATRON INTERNATIONAL, which is well known in itself and will therefore not be described precisely. It comprises a body 1 delimiting a chamber 2, a piston 3 integral with a rod 4, an orifice 5 for the entry of pressurized liquid, this liquid tending to move the piston 3 upwards, a lower chamber 6 for metering an additive, the lower part of which is connected to a pipe 7 for supplying the additive and the upper part of which opens into a chamber 8 for mixing this additive and the liquid flowing in the device, a piston 9 carried by the rod 4, which comprises at least one valve and which moves in the chamber 6, a valve in the lower part of the chamber 6, means (not visible in FIG. 1) authorizing the descent of the piston 3 beyond a determined top dead center, to allow said mixing in chamber 8 and to evacuate this mixture through an outlet orifice 10. A such a device further comprises a lower cup 1 1 said

"metering device", which can be moved axially relative to the rest of the device and can be immobilized in a determined axial position relative to this device, by means of a clamping ring, to adjust the amount of additive to be metered. FIG. 2 shows an apparatus 20 intended to be used on a building site, to allow the addition of one or more additives, liquid or in suspension in a liquid, in particular one or more dyes, to water intended for be added to the components of a material such as mortar, concrete, plaster or plaster, for the implementation of this material.

The apparatus 20 comprises a box (not shown) in which are successively placed:

- a filter 22;

- a flow limiter 23; - a first additive metering device 24;

- a second additive metering device 25;

a member 26 for connecting two bypass pipes 27 coming from these two additive metering devices 24, 25, and

- A homogenization device 28. These different members 22 to 28 are connected to each other so as to allow the passage of pressurized water through them, this water coming from the water distribution network, the upstream opening of the filter 22 being connected to a water inlet pipe 30 while the downstream opening of the homogenization device 28 is connected to a water outlet pipe 31 to which the additive has been mixed.

In addition, the device comprises four three-way valves (not shown), two of which are located immediately on either side of the device 24 and are connected by a bypass pipe making it possible to bypass ("by-pass") this device. 24, and the other two of which are located immediately on either side of the device 25 and are connected by a bypass pipe making it possible to bypass this device 25. The filter 22 makes it possible to ensure the perfect quality of the water entering the device 1, by eliminating the impurities (sand, etc.) which can, on a site, get lodged in the fittings of this pipe. in order to prevent any damage to the organs placed downstream. The flow limiter 23 makes it possible to limit the flow of water in the apparatus 20, in the event of an increase in pressure in the distribution network, so that this flow remains permanently below that admissible by the organs placed downstream, in particular the devices 24 and 25. These are respectively those sold by the company DOSATRON under the reference DM 6 and DI210, making it possible to dose an additive as a function of the amount of water passing through them, as described above. .

In the apparatus 20, each of these devices 24, 25 undergoes the following modifications:

- Closing, around the rod 4, of the metering chamber 6, so that this chamber 6 does not communicate with the mixing chamber 8, and arrangement of an upper lateral orifice in the wall which delimits this chamber 6 ; these orifices of the two devices 24, 25 are connected by the conduits 27 to the connection element 26, the latter being downstream of the device 25 most downstream;

- replacement of the standard non-return valve located at the bottom of each chamber 6 with a valve comprising a ceramic or stainless steel ball; - replacement of the threaded connection connection of the pipes 7 with a quick coupling avoiding any air intake;

- Modification of the volume of the metering chamber 6 of the device 24 (DU 6), so as to bring to 1.9% the upper limit of the metering range permitted by this device 24. The homogenization device 28 allows, at by means of the pressure of the water passing through the apparatus 20, to mix the dose of additive determined by one or by the two devices 24, 25 with this water.

In practice, either one or the other of the devices 24, 25 is used, or the two devices 24, 25 are used, depending on the proportion of additive to be dosed as a function of the amount of water passing through these devices. In the event of proportions of additive remaining in the range permitted by the device 24, only this device 24 is put into operation, the other device 25 being bypassed by means of the aforementioned bypass pipe. In the event of proportions of additive exceeding the dosage range permitted by the device 24 and not corresponding to a dosage value permitted by the device 25, the two devices 24 and 25 are put into operation and then act jointly to dose the quantity additive specifically required.

After adjusting the volume of the chambers 6 of the device (s) 24 and / or 25 to be used, the pipe (s) 7 are immersed in the additive tank (s) then a supply valve (not shown) is open to allow passage pressurized water through the various organs of the apparatus 20, in order to carry out the metering of the additive and then the homogeneous mixture of this water and this additive. The device 20 thus designed is handy, easy to use, withstands the ambient conditions (dust and humidity), possible shocks and does not need electricity to operate. It saves labor time and is very safe to operate, since it does not require electricity, pressurized air or excessive water pressure, and no moving parts are required. is apparent.

A very significant advantage of this device is that it allows a volumetric dosage of the additive proportional to the passage of water, whatever the pressure of this water. The device is also versatile and can be used as an auxiliary to any equipment (concrete mixer, spraying machine, plastering machine or silo with automatic feeding and mixing, simple mixing tank, etc.).

One or more devices 24 and / or 25 can be added to obtain the desired percentage of additive, for example beyond a proportion of 11.9%, while remaining within the usual application standards.

FIGS. 3 and 4 represent the devices 24 and 25 fitted with functional assemblies 35, 36 to allow their control by electrical means, within the framework of the second version of the apparatus 20 shown in FIG. 5. In this case, each device 24, 25 is equipped with an electrically controlled assembly 35, which makes it possible to block its operation; this set 35 includes:

- A metal rod 40 passing through the body 1 of the device at the top of the wall of this body which delimits the chamber 2, this rod being fixed axially on the piston 3;

- a plate 41, mounted on the upper part of the bodies 1 of the two devices 24, 25, and comprising

- a gear motor 42; - a pivoting plate 43 mounted on the motor axis of the gear motor 42; this axis is vertical and comprises the plate 43; the latter is movable in a horizontal plane, by rotation of said axis, between an inactive position (cf. device 24 in Figure 4), in which it is outside the path of the rod 40 and therefore does not prevent the operation of this device 24, and an active position (cf. device 25 in FIG. 4), in which it blocks the sliding of this rod 40 and prevents the operation of the device 25.

The piston 3 is thus blocked in a position in which the flow of the liquid is permitted but in which no metering is carried out.

Each device 24, 25 could comprise its own plate 41 and not a common plate as shown in FIG. 4.

The assembly 35 further comprises a presence detector 45 of the optical type, mounted on the plate 41 facing the rod 40, while the rod 40 comprises a socket 46 fixed on it, the passage of which opposite said detector 45 is suitable for being detected by this detector 45. The detector 45 is connected to electronic means for accounting for said passages of the socket 46 facing it during the operating cycles of the device. This assembly 35 therefore makes it possible to determine the quantity of liquid flowing through these devices and therefore the quantity of additive dosed.

Each assembly 36 comprises, as shown in FIG. 3:

- A longitudinal plate 50, fixed along the lower part of each device 24, 25 by means of a collar 51 tightening the base of the body 1 of the latter; a threaded rod 52 rotatably mounted on the plate 50; a gear motor 53 for driving this rod in rotation

52

- A nut 54 engaged on the latter, integral with two half-collars 55 coming to grip the metering device 1 1 of the device 24, 25;

- A knurled head screw 56, which connects these half-collars 55 to allow them to be tightened on said metering device 1 1.

The control of the geared motor thus makes it possible to raise or lower the nut 54 and therefore the metering device 1 1, to adjust the volume of additive metered at each reciprocating cycle of the pistons 3 and 7.

The assembly 36 also includes a potentiometer 57 carried by the plate 50, making it possible to detect each revolution of the rod 52 and to count these revolutions to determine the axial position of the nut 54 and of the metering device 11. FIG. 5 shows said second version of the apparatus 20.

In this case, this device comprises, in addition to the filter 22, devices 24, 25 equipped with the assemblies 35 and 36, element 26, pipes 27 and device 28:

- A turbine 60 located downstream of the filter 22, crossed by the water flowing in the device;

- an electricity generator 61 connected to this turbine 60; a storage battery 62 at 12 V, supplying the devices that comprise the sets 35 and 36, a screen / control panel 63, grouping the data collected by said sets 35 and 36, a solenoid valve 64 located upstream of the device 24 and downstream of a pipe 65, as well as an electronic card comprising the electronic members allowing the operation of the assembly (microprocessor, EPROM memories, Clock ...).

The solenoid valve 64 allows the apparatus 20 to operate on / off, as well as, when it is closed, the upstream cleaning of the apparatus 20 via line 65.

The device thus developed in electronic version is an automaton which can be programmed taking into account several parameters and is capable of calculating several formulas (density of the additive, water / cement ratio of each product, quantity of the additive according to the desired effect). It is possible to include other parameters as desired, by adding suitable sensors to transmit information to the device (current and / or future air temperature, water temperature, air humidity, aggregate humidity, etc.).

Claims

CLAIMS 1 - Process for adding one or more additives, liquid or suspended in a liquid, to a multi-component material comprising at least one liquid entering into its composition, this liquid which enters into the composition of said material reacting with one or more of the other components of this material, with a view to implementing the latter, a process characterized in that it comprises the successive operations consisting of: - determining the quantity of liquid entering into the composition of the material; - to pass this quantity of liquid through at least two volumetric dosing devices (24, 25), mounted in series, these devices (24, 25) performing an additive dosage and being able to operate independently of one of them the other, one of these devices (24, 25) being designed to carry out this dosage according to a relatively wide range of additive proportions, ranging for example from 2 to 10%, while the other device is designed to carry out this dosage according to a relatively narrow range of additive proportions, including proportions representing a percentage fraction of additive, for example ranging from 0.2 to 1.9%; - to mix the additive dosed by said devices (24, 25) and said quantity of liquid downstream of the dosing device (25) located furthest downstream, and - to combine this quantity of liquid and the additive which been mixed with the other components of the material, with a view to the implementation of the latter. 2 - Method according to claim 1, characterized in that it comprises the operations consisting of: - obtaining the quantity of liquid entering into the composition of the material from a source of liquid under pressure, and - using devices for volumetric dosage (24, 25) carrying out an additive dosage by being actuated by the pressure of said liquid. 3 - Method according to claim 1, characterized in that it comprises the operation consisting of: - using dosing devices (24, 25) actuated by an energy source specific to them, in particular electrical. 4 - Method according to one of claims 1 to 3, characterized in that the multi-component material comprising at least one liquid entering into its composition is a material of the mortar, concrete, plaster or coating type, in that said liquid is water, and in that the additive is in particular an iron oxide suspended in water, which generally constitutes a coloring product used to color such a material. 5 - Apparatus (20) for implementing the method according to one of claims 1 to 4, characterized in that it comprises: - at least a first device (25) for volumetric dosing of an additive, liquid or suspended in a liquid, as a function of a predetermined quantity of liquid, this device (25) being designed to carry out this dosage according to a relatively wide range of additive proportions, ranging for example from 2 to 10%; - at least a second device (24) of the same type, designed to carry out this dosage according to a relatively narrow range of additive proportions, including proportions representing a percentage fraction of additive, for example ranging from 0.2 to 1 .9%, the two aforementioned devices (24, 25) being connected in series; - means (26, 27) forming derivations, making it possible to collect the dose of additive determined by one or both dosing devices (24, 25) and to mix this dose with said quantity of liquid downstream of the device ( 25) located furthest downstream, and - means (28) for then mixing the quantity of liquid thus added with additive to the other constituents of the material, for the use of the latter. 6 - Apparatus (20) according to claim 5, characterized in that the dosing devices (24, 25) are of the type actuated automatically by the quantity of liquid entering into the composition of the material, which is under pressure and which passes through them. 7 - Apparatus (20) according to claim 6, characterized in that said first dosing device (25) is that sold by the company DOSATRON INTERNATIONAL under the reference "DI210" and in that the second device (24) is that sold by this same company under the reference "DM 6", the dosage range allowed by this second device (24) having been increased to go, in upper limit, from 1.6 to 1.9%, by an increase in the capacity maximum of the dosing chamber (6) of this device (24). 8 - Apparatus (20) according to claim 7, characterized in that each of these two devices (24, 25) is modified to enable it to dose abrasive or non-abrasive additives, in particular as mentioned above, these modifications consisting of: - in the upper closure of the dosing chamber (6) of each device (24, 25), to isolate this chamber (6) from said liquid which passes through the device, in order to prevent any mixing of this additive and this liquid within the device , and - in the provision of a lateral opening in the wall delimiting this chamber (6), to allow the ejection of the quantity dosed by each device not in the device but in a pipe located downstream of the two devices ( 24, 25). 9 - Apparatus (20) according to claim 7 or claim 8, characterized in that each of the two dosing devices (24, 25) comprises at least one of the following modifications: - the non-return valve located at the lower part of the dosing chamber (6) of each device comprises a ceramic or stainless steel ball; - the connection of the additive suction tube (7) is of the quick-connect type to avoid air intakes (instead of a conventional threaded connection). 10 - Apparatus (20) according to one of claims 5 to 9, characterized in that it comprises at least one of the following arrangements: - an upstream valve for controlling the flow of the liquid, the control handle of which is located in the exterior part of a box (21) housing the device (20); - a filter (22) located upstream of the dosing device (24) located upstream, to filter said liquid; - a flow limiter upstream of the dosing device (24) located upstream, limiting the flow rate of the liquid so that this flow rate remains below the maximum flow rate that can be supported by the dosing devices (24, 25); - a homogenization device (28) for mixing with the liquid the dose of additive determined by one or both dosing devices (24, 25); - a non-return valve, downstream of the dosing devices (24, 25) and upstream of the connection of the additive supply branches; - a dosing valve operating with the pressure of the liquid, which can program the quantity of liquid to inject; - a three-way cleaning valve, which includes water outlets equipped with quick couplings of identical diameters to those allowing the connection of the additive suction pipes, and a pipe connected to a cleaning gun. 1 1 - Apparatus (20) according to one of claims 5 to 10, characterized in that it comprises: - a turbine (60) through which said liquid entering into the composition of the material, this turbine (60) being connected to an electricity generator (61); - means (35, 36) electrically actuated, performing at least one of the following functions: (i) controlling the switching on/off of each dosing device (24, 25); (ii) counting the number of operating cycles of each dosing device (24, 25), to make it possible to determine the quantity of liquid flowed through each device and, therefore, the quantity of additive dosed; (iii) controlling the modification of the quantity of additive dosed by each device (24, 25). 12 - Apparatus (20) according to claim 1 1, characterized in that each dosing device (24, 25) comprises in particular a body

(1) delimiting a chamber (2) and a piston (3) movable in this chamber

(2); and in that the means (35) fulfilling the function of controlling the switching on/off of each dosing device (24, 25) comprise:

- a metal rod (40) passing through the body (1) of a dosing device (24, 25) at the top of the wall of this body, this rod being fixed axially on the piston (3);

- a plate (41), mounted on the upper part of the body (1); - a gear motor (42) carried by the plate (41); - a pivoting plate (43) mounted on the motor axis of the gear motor (42); this axis is vertical and includes the plate (43); the latter is movable in a horizontal plane, by rotation of said axis, between an inactive position, in which it is outside the trajectory of the rod (40) and therefore does not prevent the operation of the device (24, 25) , and an active position, in which it blocks the sliding of this rod (40) and prevents the operation of the device (24, 25).

13 - Apparatus (20) according to claim 1 1 or claim 12, characterized in that each dosing device (24, 25) comprises in particular a body (1) delimiting a chamber (2) and a piston (3) movable in this room (2); and in that the means (35) fulfilling the function of counting the number of operating cycles of each dosing device (24, 25), to make it possible to determine the quantity of liquid flowed through each device and, consequently, the quantity of additive dosed, include:

- a metal rod (40) passing through the body (1) of a dosing device (24, 25) at the top of the wall of this body, this rod being fixed axially on the piston (3); - a plate (41), mounted on the upper part of the body (1);

- a presence detector (45) of the optical type, mounted on the plate (41) facing the rod (40);

- a socket 46 fixed on the rod (40), the passage of which opposite said detector (45) is capable of being detected by this detector (45), and - electronic means for accounting for said passages of the socket (46) in gaze of the detector (45) during the operating cycles of the device.

14 - Apparatus (20) according to one of claims 1 1 to 13, characterized in that each dosing device (24, 25) comprises in particular a body (1) and a lower cup (1 1), called "doser" , which can be moved axially relative to the rest of the device and be immobilized in a determined axial position relative to this device to adjust the quantity of additive to be dosed, and in that the means (36) fulfilling the function of controlling the modification of the quantity of additive dosed by each device (24, 25) include: - a longitudinal plate (50), fixed along the lower part of each device (24, 25) by means of a collar (51) tightening the base of the body (1) of the latter;

- a threaded rod (52) rotatably mounted on the plate (50); - a gear motor (53) for rotating this rod (52);

- a nut (54) engaged on the latter, secured to two half-collars (55) enclosing the doser (1 1) of the device (24, 25);

- a knurled head screw (56), which connects these half-collars (55) to allow them to be tightened on said dispenser (1 1).

15 - Use of the method and the apparatus (20) according to one of claims 1 to 14 for the dosage of a coloring product, in particular an iron oxide suspended in water, and the mixing of this product water coloring used in the composition of a material such as mortar, plaster or coating, to color this material.

16 - Use of the method and the apparatus (20) according to one of claims 1 to 14 for the dosage of additives or adjuvants and the mixing of these additives or adjuvants with water entering into the composition of a mortar or concrete type material.