Mixing device, projection system and associated process

Abstract

The mixing device (5) for mixing: - a composition S2 comprising at least one compound selected from a silicate and silicic acid, and - a mixture B comprising at least one powdered material and a composition S1 comprising at least one compound selected from a silicate and silicic acid, comprises a mixing chamber (16) extending between an inlet interface (5a) and an outlet interface (5b), a lateral surface of the mixing chamber extending between the inlet interface and the outlet interface, the lateral surface comprising at least one hole (17) configured to be fed by composition S2 so that the mixture B projected at the inlet interface towards the outlet interface is mixed with the composition S2 flowing through the hole to obtain at the outlet interface a mixture A comprising composition S2 and mixture B. Figure for the abbreviation: Fig 4

Description

Title of the invention: Mixing device, projection system and associated method

[0001] The present invention relates to the projection of a mixture comprising at least one powdered material and a composition onto a surface.

[0002] The present invention relates more particularly to a mixing device for mixing a composition S2 selected from a composition comprising at least one silicate and a solution comprising silicic acid, and a mixture B comprising at least one powdered material and a composition SI selected from a composition comprising at least one silicate and a solution comprising silicic acid.

[0003] The present invention further relates to a method for mixing composition S2 and mixture B, and a system and method for projecting onto a surface a mixture A comprising at least composition S2 and mixture B.

[0004] It is known to spray concrete onto a surface to erect or repair infrastructure such as bridges or tunnels or to apply a surface coating to a structure.

[0005] It is known to spray concrete by dry method by transferring a mixture of cement and aggregates previously mixed into a pipe, then the mixture is sprayed using compressed air into a spray lance and moistened with water in said lance before being sprayed from the outlet of the spray lance onto the surface.

[0006] As the cement and aggregate mixture is made before the addition of water, the mixture releases dust which volatilizes, resulting in losses of cement and aggregate.

[0007] The mixture is moistened in the projection lance so that the wetting of the mixture is not sufficiently controllable to prevent a heterogeneous mixture of cement, aggregates and water.

[0008] Furthermore, the rheology of the mixture is not controllable.

[0009] It is known to spray concrete by wet method.

[0010] A mixture of cement, aggregates and water is generally made in a concrete batching plant and transferred via a transfer pipe into a spray nozzle to be sprayed.

[0011] However, as the transferred mixture is viscous and generates friction, the length of the transfer pipe between the concrete plant and the spraying nozzle is generally limited to three hundred meters and the power of the spraying of the mixture at the outlet of the spraying nozzle is limited.

[0012] In addition, since the transferred mixture is viscous, the risk of blockages forming in the transfer pipe is high.

[0013] Furthermore, it is necessary to clean the inside of the transfer pipe along its entire length and the spray nozzle after concrete spraying is complete to prevent the mixture from solidifying and clogging the transfer pipe and nozzle. Cleaning results in significant losses of the mixture.

[0014] The mixture of cement and aggregates may further include fibers, for example metallic.

[0015] When the mixture is sprayed dry, the presence of fibers in the mixture further prevents the obtaining of a heterogeneous mixture of cement, aggregates and water.

[0016] When the mixture is sprayed wet, the presence of fibers in the mixture promotes the formation of plugs in the transfer pipe.

[0017] The object of the invention is to overcome all or part of the disadvantages of dry and wet spraying devices.

[0018] The invention relates to a mixing device for mixing:

[0019] - a composition S2 comprising at least one compound selected from a silicate and silicic acid and

[0020] - a mixture B comprising at least one powdered material and an SI composition comprising at least one compound selected from a silicate and silicic acid.

[0021] The mixing device includes a mixing chamber extending between an inlet interface and an outlet interface, a lateral surface of the mixing chamber extending between the inlet interface and the outlet interface, the lateral surface including at least one hole configured to be fed by composition S2 so that the mixture B projected at the inlet interface towards the outlet interface is mixed with the composition S2 flowing through the hole to obtain at the outlet interface a mixture A comprising composition S2 and mixture B.

[0022] As previously stated, composition S2 comprises at least one silicate or at least silicic acid.

[0023] Preferably, the silicate is an alkali metal silicate. Preferably, the alkali metal silicate is selected from potassium silicate, sodium silicate, and mixtures thereof.

[0024] Preferably, the composition S2 which includes silicic acid may further include an alkali metal hydroxide, which may be chosen from potassium hydroxide, sodium hydroxide and their mixture.

[0025] The preferred embodiments described for composition S2 can be applied to composition SL

[0026] Composition SI and composition S2 may be identical or different.

[0027] Preferably, composition SI and composition S2 are identical.

[0028] Advantageously, composition S2 is free of water.

[0029] Advantageously, the SI composition is free of water.

[0030] Particularly advantageously, composition S2 and composition SI are free of water.

[0031] Preferably, the device is configured to mix composition S2 and mixture B further comprising fibers preferably having a length greater than or equal to 10 mm, preferably from 10 to 100 mm, and more preferably from 30 to 100 mm.

[0032] Advantageously, the device is configured to mix composition S2 and mixture B further comprising at least one granular material.

[0033] Preferably, the mixing chamber is cylindrical, with the inlet and outlet interfaces located at the ends of the cylinder.

[0034] Advantageously, the device further comprises a feed chamber surrounding the lateral surface of the mixing chamber and comprising a connection for receiving composition S2 so that composition S2 flowing through the feed chamber flows through each hole.

[0035] Preferably, the device comprises a plurality of holes distributed over the lateral surface.

[0036] A projection system is also proposed for projecting a mixture A onto a surface, mixture A comprising at least:

[0037] - a composition S2 comprising at least one compound selected from a silicate and silicic acid, and

[0038] - a mixture B,

[0039] The system comprises:

[0040] - a mixer configured to mix at least one powdered material and a SI composition comprising at least one compound selected from a silicate and silicic acid to obtain a mixture B,

[0041] - a mixing device as defined above, and

[0042] - a projection device configured to project mixture B into the device mix to obtain mixture A and project mixture A onto the surface.

[0043] Preferably, the system further comprises feeding means connected to each hole in the side surface of the mixing device and configured to supply each hole with composition S2 when the mixture is projected into the mixing device and to supply each hole with a rinsing product when the mixing device is rinsed.

[0044] Advantageously, the supply means comprise a valve having a first inlet configured to be supplied by composition S2, a second inlet configured to be supplied by the rinsing product and an outlet connected to each hole on the side surface of the mixing device.

[0045] Preferably, the system further comprises a projection lance configured to project the mixture A onto the surface.

[0046] A mixing process is also proposed for mixing:

[0047] - a composition S2 comprising at least one compound selected from a silicate and silicic acid, and

[0048] - a mixture B comprising at least one powdered material and an SI composition comprising at least one compound selected from a silicate and silicic acid.

[0049] The process comprises:

[0050] - the injection of composition S2 through at least one hole in a lateral surface of a mixing chamber of a mixing device as defined above, and

[0051] - the projection of mixture B from the inlet interface to the outlet interface of the mixing device to obtain at the output interface a mixture A comprising composition S2 and mixture B.

[0052] A method is proposed for projecting a mixture A onto a surface, the mixture A comprising at least:

[0053] - a composition S2 comprising at least one compound selected from a silicate and silicic acid, and

[0054] - a mixture B.

[0055] The process comprises:

[0056] - a first mixing step of at least one powdered material and a SI composition comprising at least one compound selected from a silicate and silicic acid to obtain a mixture B,

[0057] - a projection of mixture B,

[0058] - a second mixing step as defined above, and

[0059] - a projection of mixture A onto the surface.

[0060] Preferably, the first mixing step includes mixing the powdered material, the SI composition and fibers preferably having a length greater than or equal to 10 mm, preferably from 10 to 100 mm, and more preferably from 30 to 100 mm.

[0061] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which:

[0062] [Fig.1]

[0063] schematically illustrates an example of a projection system according to the invention;

[0064] [Fig.2]

[0065] schematically illustrates an example of a barrel according to the invention;

[0066] [Fig.3]

[0067] schematically illustrates a partial view of an example embodiment of the mixing device according to the invention;

[0068] [Fig.4]

[0069] schematically illustrates a longitudinal section of the example embodiment of the mixing device according to the invention;

[0070] [Fig.5]

[0071] schematically illustrates an example of an embodiment of a mixer according to the invention, and

[0072] [Fig.6]

[0073] schematically illustrates an example of a method for projecting a mixture A.

[0074] Fig. 1 illustrates an example of a projection system 1 of a mixture A comprising a mixture B and a composition S2 onto a surface 2.

[0075] Composition S2 can be as defined above.

[0076] The projection system 1 includes a mixer 3, a projection device 4, a mixing device 5, a projection lance 6 measuring for example between six and eight meters, and a transfer pipe 7 measuring for example between 5 and 500 meters.

[0077] The projection system 1 further includes a silo 8 and a reservoir 9 storing a composition SI selected from a composition comprising at least one silicate and a solution comprising silicic acid.

[0078] The projection device 4 further includes a projection machine 10.

[0079] The SI composition can be as defined above.

[0080] Silo 8 stores a mixture C comprising a powdered material, for example a clay or mortar or cement or metakaolin.

[0081] The silo 8 includes, for example, a rigid or flexible container with a volume of, for example, between 1 m3 and 20 m3.

[0082] The mixture C stored in the silo 8 may further comprise one or more granular materials including slag, sands and aggregates, and generally has a moisture content of less than 6%.

[0083] The mixture C stored in silo 8 may further include at least one adjuvant.

[0084] The mixture C stored in silo 8 may further comprise pigments.

[0085] The mixture C stored in silo 8 may further comprise fibers.

[0086] The fibers are selected from basalt, cast iron, carbon, and aramid fibers, polyethylene, metal and alloys, natural fibers, hybrid fibers, glass fibers, plastic fibers, and mixtures thereof, preferably alkali-resistant glass fibers.

[0087] The fibers are preferably long fibers having a length greater than or equal to 10 mm, preferably from 10 to 100 mm, and more preferably from 30 to 100 mm.

[0088] A fluid inlet 3a of the mixer 3 is connected to the reservoir 9 via a first pump 9a so that the composition SI is injected by the first pump 9a into the mixer 3.

[0089] The first pump 9a can be a variable flow, constant pressure or constant flow pump.

[0090] The mixer 3 is suitable for mixing the mixture C stored in the silo 8 with the composition SI to obtain a partially wet mixture B comprising the powdery material stored in the silo 8, the composition SI and may further contain at least one element among the fibers, the granular material, an adjuvant and pigments.

[0091] The mixer 3 is also capable of delivering the mixture B obtained into, for example, a hopper 19 of the projection machine 10, the projection machine 10 being intended to be supplied by the mixture B delivered by the mixer 3.

[0092] An outlet of the projection machine 10 is connected to a first end of the transfer pipe 7.

[0093] The projection machine 10 may, for example, be of the rotor type, also known as a "barrel" type, for example with trapezoidal cells. The rotor projection machine is further connected to a compressed air source 11 intended to supply the projection machine 10 with compressed air to successively project the contents of each cell into the transfer pipe 7.

[0094] The trapezoidal cells of the barrel have a larger cross-section than, for example, circular cells, facilitating the projection of the mixture B by the projection machine 10, in particular when the mixture B includes long fibers.

[0095] The compressed air source 11 includes, for example, a compressor powered by an electrical network or a compressor driven by a heat engine.

[0096] The projection machine 10 and the compressed air source 11 can each be arranged on a trolley facilitating the movement of the projection machine 10 and the compressed air source 11.

[0097] Of course, the projection machine 10 can be of another type, for example of the piston type.

[0098] A second end of the transfer pipe 7 is connected to an inlet interface 5a of the mixing device 5.

[0099] The mixing device 5 further includes an output interface 5b connected to the projection lance 6, and a connection 5c intended to be supplied by the composition S2.

[0100] The projection machine 10 is suitable for projecting the mixture B into the mixing device 5 via the transfer pipe 7 so that the mixture B is impregnated by the composition S2 delivered on the connection 5c of the mixing device 5.

[0101] The projection system 1 may further include supply means connecting the connection 5c of the mixing device 5 to the reservoir 9 via a second pump 9b and connecting the connection 5c of the mixing device 5 to a source of rinsing product 12.

[0102] The rinsing product includes, for example, water.

[0103] The supply means include for example a valve 13, for example a guillotine valve, a butterfly valve or a simple valve.

[0104] The valve 13 has a first inlet 13a connected to a discharge outlet of the second pump 9b, a second inlet 13b connected to the source of rinsing product 12 and an outlet 13c connected to the connection 5c of the mixing device 5.

[0105] The valve 13 can be operated by a lance holder OP holding the lance 6.

[0106] Alternatively, the power supply means connect the 5c connection of the device to mixing 5 to the reservoir 9 via the second pump 9b, the supply means not connecting the connection 5c of the mixing device 5 to the source of rinsing product 12. The supply means include for example a valve having an inlet connected to the discharge outlet of the second pump 9b and an outlet connected to the connection 5c of the mixing device 5.

[0107] The mixing device 5 is capable of mixing the mixture B projected at the inlet interface 5a towards the outlet interface 5b with the composition S2 to obtain at the outlet interface a mixture A.

[0108] Mixture A comprises mixture B and composition S2.

[0109] The output interface 5b of the mixing device 5 is connected to the lance 6.

[0110] The projection lance 6 is held by an operator OP (lance holder) and is intended to project the mixture A onto the surface 2.

[0111] Alternatively, the projection lance 6 is held by a robot to automate the projection of mixture A.

[0112] The addition of aggregates in the mixture allows the mixture A to be compacted when projected by the projection lance 6 onto the surface 2 and improves the conveyance of the mixture B in the transfer pipe 7.

[0113] The surface 2 can be made of concrete, mortar, stone, geopolymer, resin or a continuous metallic surface.

[0114] Fig. 2 illustrates an example of a barrel 14 of the projection machine 10.

[0115] The barrel 14 has trapezoidal sections 15.

[0116] Figures 3 and 4 schematically illustrate respectively a partial view and a longitudinal section of an example embodiment of the mixing device 5.

[0117] The mixing device 5 includes a mixing chamber 16 extending between the inlet interfaces 5a and outlet interface 5b, and a lateral surface extending between the inlet and outlet interfaces 5a, 5b.

[0118] The mixing chamber 16 is for example cylindrical, with the inlet interfaces 5a and outlet interfaces 5b located at the ends of the cylinder.

[0119] The lateral surface includes holes 17 distributed over the lateral surface, each hole having for example a diameter of 0.01 mm to 30 mm, the cylindrical mixing chamber 16 having for example an internal diameter between 30 mm and 100 mm and being made for example from a hollow tube 16a.

[0120] The hollow tube 16a is for example made of stainless steel.

[0121] The holes 17 are arranged on the lateral surface for example in a line along a longitudinal direction of the mixing chamber 16, in a staggered pattern, in a zigzag pattern, or randomly.

[0122] Alternatively, the lateral surface includes at least one hole.

[0123] The mixing device 5 further includes a feed chamber 18 surrounding the lateral surface of the mixing chamber 16 and including the connection 5c so that the composition S2 delivered by the feed means on the connection 5c flows through the feed chamber and then through each hole 17 when the mixture A is projected onto the surface 2.

[0124] As shown ([Fig.1]), composition S2 is delivered by the second pump 9b on the connection 5c via the supply means and is identical to composition SI, compositions SI and S2 being stored in the tank 9. In other words, composition SI and composition S2 are the same compositions.

[0125] Alternatively, the identical compositions SI, S2 are stored in two separate tanks.

[0126] According to yet another variant, composition SI is different from composition S2, composition SI, S2 being stored in different tanks.

[0127] The feed chamber 18 is for example made from a hollow tube 18a held at its ends on the mixing chamber 16 by two flanges 18b, 18c welded onto the tube forming the mixing chamber 16.

[0128] Seals 19 ensure the seal between the hollow tube 16a forming the mixing chamber 16 and the hollow tube 18a forming the feed chamber 18.

[0129] Fig. 5 schematically illustrates an example of an embodiment of mixer 3.

[0130] The mixer 3 comprises the hopper 19, a screw 20, a drive means 21 of the screw 20 and an injection means 22 of the composition SI connected to the fluid inlet 3 a of the mixer 3.

[0131] The hopper 19 is connected to the screw 20 via a channel 23.

[0132] The injection means 22 is suitable for injecting the composition SI into the channel 23 and includes, for example, a pear.

[0133] The hopper 19, the screw 20 and the injection means 22 are arranged relative to the silo 8 so that the mixture C contained in the silo 8 is poured into the hopper 19 by gravity and then poured into the screw 20 by gravity through the channel 23 and is wetted by the composition SI injected by the injection means 22 to obtain the mixture B.

[0134] The screw conveyor 20 is arranged in relation to the projection machine 10 so that the mixture B is conveyed by the screw conveyor 20 above the projection machine 10, and is discharged into the projection machine 10 by gravity.

[0135] Alternatively, the worm screw 20 is replaced by a conveyor belt.

[0136] Figure 6 schematically illustrates a method of projecting mixture A onto the surface 2 implementing projection system 1.

[0137] During a first mixing step 30 or pre-wetting step, the mixer 3 mixes the mixture C stored in the silo 8 with the composition SI to obtain the mixture B, and delivers the resulting mixture continuously into the spraying machine 10.

[0138] Alternatively, mixer 3 mixes and stores mixture C stored in silo 8 with composition SI, and discharges the resulting mixture B (batch operation).

[0139] The mixing carried out by the mixer 3 makes it possible to fix the fine particles of the powdery material for and where applicable the fine particles of one or more elements among the granular material, adjuvant, pigment, fibers of the mixture C so that there is no dust when loading the projection machine 10 facilitating cleaning operations, increasing the life of the projection machine 10 and reducing the losses of the mixture delivered by the silo 8 by dry means known in the prior art.

[0140] Furthermore, the mixing of composition SI with mixture C contained in silo 8 prevents the lance operator and personnel near the projection machine 10 from inhaling dust and fine particles, unlike a dry projection system known in the prior art.

[0141] Furthermore, the addition of composition SI enables the chemical reaction leading to mixture A to be initiated.

[0142] The mass flow rate of mixture C entering the mixer 3 is for example between 40 kg / min and 120 kg / min, preferably between 55 and 100 kg / min.

[0143] The flow rate of the SI composition entering the mixer 3 is for example between 3 l / min and 25 l / min, preferably between 5 l / min and 10 l / min.

[0144] The mass ratio of the SI composition on the C Sl / C mixture is for example between 5 / 100 and 50 / 100, preferably between 10 / 100 and 24 / 100.

[0145] The flow rate of composition SI and the mass flow rate of mixture C are adjustable allowing good control of the S1 / C ratio.

[0146] The SI / C ratio is determined based on the wettability of the powdered material compounds and aggregates, the flow of mixture C, and the reactivity of the components of mixture A.

[0147] During a projection step 31, the mixture B is projected by the projection machine 10 into the transfer pipe 7 and then into the mixing device 5. As the chemical reaction resulting in the mixture A was triggered during the pre-wetting step 30, the chemical reaction continues in the transfer pipe 7.

[0148] The flow rate of the composition SI and the mass flow rate of the mixture C are chosen for example so that the mass flow rate of supplying mixture B to the projection machine 10 is equal to the mass flow rate of the mixture B projected by the projection machine 10.

[0149] The mixture B is projected by the projection machine 10 into the mixing device 5 via the transfer pipe 7.

[0150] During a second mixing step 32 or wetting step, the composition S2 is injected into the mixing device 5.

[0151] Mixture B is projected through the mixing chamber 16 from the inlet interface to the outlet interface of the mixing device 5 and is mixed with composition S2 flowing into the mixing chamber 16 through the hole 17 to obtain mixture A at the outlet interface of the mixing device 5.

[0152] The injection of composition S2 allows the chemical reaction triggered during the pre-wetting step 30 of the mixture C by the composition SI in the mixer 3 in the mixing device 5 to continue to obtain the mixture A.

[0153] The mass flow rate of the mixture B entering the mixing device 5 is for example between 44 kg / min and 157 kg / min, preferably between 62 and 115 kg / min.

[0154] The flow rate of composition S2 entering the mixing device 5 is for example between 11 / min and 25 l / min, preferably between 1.5 and 5 l / min.

[0155] The mass ratio of composition S2 to mixture B S2 / B is for example between 2 / 100 and 25 / 100, preferably between 3 / 100 and 15 / 100.

[0156] The flow rate of composition S2 and the mass flow rate of mixture B are adjustable allowing good control of the S2 / B ratio.

[0157] The S2 / B ratio is determined from the mass ratio of the compositions SI and S2 on the mixture C (Sl+S2) / C of the targeted mixture A and the ratio Sl / C.

[0158] The mass flow rate of mixture B is compatible with all commercially available projection machines.

[0159] The flow rate of composition S2 is compatible with precise adjustment by the OP lance holder.

[0160] The wetting operation in the mixing chamber reduces the amount of solution required compared to wet spraying. The resulting product A is of better quality.

[0161] The pre-wetting step allows control of the rheology of mixture A and to obtain a more homogeneous mixture A.

[0162] Then during a projection step 33 of the mixture A, the mixture A is projected under the effect of compressed air delivered by the compressed air source 11 into the projection lance 6 to be projected onto the surface 2.

[0163] The mixing device 5 is continuously supplied so that the projection of the mixture A onto the surface 2 is carried out continuously, increasing the rate of projection of the mixture A onto the surface 2.

[0164] The mass flow rate of the mixture A projected by the projection lance 6 is for example between 45 kg / min and 195 kg / min, preferably between 64 and 123 kg / min.

[0165] The projection pressure of the mixture A at the outlet of the projection lance 6 is for example between 5 bars and 25 bars.

[0166] The projection pressure of mixture A promotes the adhesion of mixture A to the support 2 and promotes low porosity in mixture A.

[0167] In addition, the projection pressure values ​​of mixture A at the outlet of the projection lance 6 are compatible with manual and robotic projections.

[0168] The setting time of mixture A is for example between 10 min and 5 days, preferably between 1h and 16 h allowing to project a mixture A having a very rapid setting to a very slow setting.

[0169] The projection machine 10 and the mixing device 5 make it possible to obtain and project the mixture A continuously comprising long fibers, of lengths greater than or equal to 10 mm, preferably from 10 to 100 mm, and more preferably from 30 to 100 mm, abrasive, for example metallic, without damage to the projection system 1, and to project the mixture A continuously to obtain a coating comprising said fibers on the surface 2.

[0170] In addition, the projection machine 10 and the mixing device 5 make it possible to project the mixture A containing a large total mass of fibers, for example greater than 30 kg / m3 and up to 150 kg / m3.

[0171] When mixture B comprises a clay so that mixture A forms a geopolymer, a gas or a chemical element can be introduced into mixture B, into composition SI or composition S2, or into the mixing chamber 16 via connection 5c to form a geopolymer foam.

[0172] When the operations of projecting mixture A onto surface 2 have ended, the system 1 comprising the mixing device 5 and the projection lance 6 is cleaned.

[0173] Advantageously, compared with a wet spraying device, the adhesion of mixture B to the spraying machine 10 and to the walls of the transfer pipe 7 is greatly reduced so that mixture B is evacuated from said machine and said pipe when compressed air is injected from the compressed air source 11.

[0174] To clean system 1, simply rinse the mixing device 5 containing mixture A and the spray lance 6 containing mixture A.

[0175] During the rinsing of the mixing device 5 and the spray lance 7, the supply means supply each hole 17 of the mixing device 5 with the rinsing product delivered by the rinsing product source 12.

[0176] The feeding means no longer deliver composition S2.

[0177] The valve 13 of the supply means is switched so that the second inlet 13b is connected to the output 13c.

[0178] Since the spraying machine 10 and the transfer pipe 7 do not need to be rinsed during the cleaning of the system 1, the amount of mixture A lost is reduced compared to a wet spraying system known in the prior art.

[0179] Furthermore, as mixture B is partially wet, the passage of mixture B through the transfer pipe 7 generates less friction, allowing a transfer pipe 7 to be longer than the transfer pipe of a known prior art wet spraying system, while reducing the risk of blockages forming in said pipe 7 and allowing a spraying power of mixture A to be greater than that of a known prior art wet spraying system.

[0180] The use of the mixing device 5 makes it possible to control the rheology of the mixture by dosing the quantity of composition S2 injected into the mixture B whose chemical reaction is initiated and in progress, to reduce the dispersion of fine particles (dust) by receiving the wet mixture B at the inlet, the use of a transfer pipe 7 of great length, for example between 5 and 500 m, and to increase the projection power by conveying the wet mixture B through the transfer pipe 8.

[0181] The mixing device 5 makes it possible, for example, to obtain a mixture A whose rheology is compatible with vertical surface holding in a thickness range between 5 and 100 mm.

[0182] System 1 combines aspects of dry spraying (spraying machine 10 and mixing device 5) and aspects of wet spraying (mixer 3).

[0183] System 1 makes it possible to obtain a ratio of powdered material / SI, S2 compositions of for example between 0.3 and 5.

[0184] Since mixture A is obtained at the outlet of the mixing device 5, system 1 allows the rapid setting mixture A to be projected.

[0185] "As mixture A is obtained following the injection of compositions SI and S2 in two different places (mixer 3 and mixing device 5), the powdery material contained in silo 8 is intimately mixed with compositions SI, S2 to obtain the binder of mixture A so that mixture A is homogeneous.

[0186] Depending on the nature of the powdered material and the nature of the SI and S2 compositions, the binder is cement or a geopolymer or an alkali-activated material.

[0187] System 1 makes it possible to increase the impact and penetration pressure of mixture A on surface 2 so that the adhesion of mixture A on the concrete surface 2 is improved, and furthermore to obtain good compactness of the coating formed by mixture A on surface 2 with low porosity when mixture B includes aggregates compressing the fresh layer of mixture A on surface 2.

[0188] System 1 can also be implemented with any type of packaging for compositions SI, S2, for example a can, a drum or a container.

[0189] Furthermore, the mixture comprising the powdered material, and where appropriate one or more elements among the fibers, the granular material, additives, pigment can be stored in any type of packaging, for example bags, silos, containers with flexible or rigid packaging.

Claims

Demands

1. A mixing device (5) for mixing: - a composition S2 comprising at least one compound selected from a silicate and silicic acid and - a mixture B comprising at least one powdered material and a composition S1 comprising at least one compound selected from a silicate and silicic acid, characterized in that the mixing device comprises a mixing chamber (16) extending between an inlet interface (5a) and an outlet interface (5b), a lateral surface of the mixing chamber extending between the inlet interface and the outlet interface, the lateral surface comprising at least one hole (17) configured to be fed by composition S2 such that the mixture B projected at the inlet interface towards the outlet interface is mixed with the composition S2 flowing through the hole to obtain at the outlet interface a mixture A comprising composition S2 and the mixture R

2. Device according to claim 1, configured to mix composition S2 and mixture B further comprising fibers having a length greater than or equal to 10 mm, preferably from 10 to 100 mm, and more preferably from 30 to 100 mm.

3. Mixing device according to claim 1 or 2, wherein the mixing chamber (16) is cylindrical, the inlet interfaces (5a) and outlet interface (5b) being located at the ends of the cylinder.

4. Device according to any one of claims 1 to 3, further comprising a feed chamber (18) surrounding the lateral surface of the mixing chamber (16) and comprising a connection (5c) for receiving composition S2 such that composition S2 flowing through the feed chamber flows through each hole (17).

5. Device according to any one of claims 1 to 4, comprising a plurality of holes (17) distributed over the lateral surface.

6. Projection system (1) for projecting onto a surface (2) a mixture A, mixture A comprising at least: - a composition S2 comprising at least one compound selected from a silicate and silicic acid, and - a mixture B, characterized in that the system comprises: - a mixer (3) configured to mix at least one powdery material and an SI composition comprising at least one compound selected from a silicate and silicic acid to obtain a mixture B, - a mixing device (5) according to any one of claims 1 to 5, and - a projection device (10) configured to project the mixture B into the mixing device to obtain the mixture A and project the mixture A onto the surface (2).

7. System according to claim 6, further comprising feeding means connected to each hole (17) of the lateral surface of the mixing device (5) and configured to supply each hole with composition S2 when the mixture B is projected into the mixing device and to supply each hole with a rinsing product when the mixing device is rinsed.

8. System according to claim 7, wherein the supply means comprise a valve (13) having a first inlet (13a) configured to be supplied by composition S2, a second inlet (13b) configured to be supplied by the rinsing product and an outlet (13c) connected to each hole (17) of the side surface of the mixing device (5).

9. System according to any one of claims 6 to 8, further comprising a projection lance (6) configured to project the mixture A onto the surface (2).

10. A mixing process for mixing: - a composition S2 comprising at least one compound selected from a silicate and silicic acid, and - a mixture B comprising at least one powdered material and a composition S1 comprising at least one compound selected from a silicate and silicic acid, characterized in that the process comprises: - injecting composition S2 through at least one hole (17) in a lateral surface of a mixing chamber (16) of a mixing device according to any one of claims 1 to 5, and

11.

12. - the projection of mixture B from the input interface to the output interface of the mixing device to obtain at the output interface a mixture A comprising composition S2 and mixture B. Method of projecting (1) a mixture A onto a surface (2), the mixture A comprising at least: - a composition S2 comprising at least one compound selected from a silicate and silicic acid, and - a mixture B, characterized in that the process comprises: - a first mixing step of at least one powdered material and an SI composition comprising at least one compound selected from a silicate and silicic acid to obtain a mixture B, - a projection of mixture B, - a second mixing step according to claim 11, and - a projection of mixture A onto the surface (2). A process according to claim 11, wherein the first mixing step comprises mixing the powdered material, the SI composition and fibers preferably having a length greater than or equal to 10 mm, preferably from 10 to 100 mm, and more preferably from 30 to 100 mm.

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