EP4182064A1

EP4182064A1 - Device and method for adding and mixing an additive into a hydraulic setting mixture

Info

Publication number: EP4182064A1
Application number: EP21739705.8A
Authority: EP
Inventors: Beat Schnider; Heinz Meier; Carsten Rieger
Original assignee: Sika Technology AG
Current assignee: Sika Technology AG
Priority date: 2020-07-14
Filing date: 2021-07-07
Publication date: 2023-05-24
Also published as: US20230219045A1; EP3939695A1; WO2022013043A1

Abstract

The invention relates to a device (100) for adding and mixing an additive into a hydraulic setting mixture, comprising a tubular hollow space (130) allowing the hydraulic mixture to flow along an intended flow direction (133), wherein a static flow-influencing element (150) protrudes into the hollow space (130), in which an opening (160) feeding into the hollow space (130) is provided for introducing the additive.

Description

APPARATUS AND METHOD FOR ADDING AND BLENDING AN ADDITIVE INTO A HYDRAULICALLY SETTABLE MIXTURE Technical Field

The invention relates to a device for adding and mixing an additive into a hydraulically settable mixture and an arrangement for conveying a hydraulically settable mixture. The invention also relates to the use of such devices in the production of shaped bodies by additive manufacturing and/or in the application of shotcrete or shotcrete. The invention also relates to a method for adding and mixing in an additive into a hydraulically settable mixture.

State of the art

Dosing or mixing small amounts of a substance, eg an additive, into a pumpable mixture is essential for many applications. However, thorough mixing is often difficult to achieve, particularly in the case of heterogeneous mixtures containing solids. The metering of additives into hydraulically settable mixtures, which usually have a relatively high proportion of solids in the form of sand, gravel and cement with very different particle sizes and shapes, is particularly problematic. The addition of additives is made more difficult in particular by the fact that hydraulically settable mixtures, such as concrete, represent an extremely compact mass which does not absorb liquid additives without assistance. The use of dynamic mixing devices, for example, is known for admixing additives. The additive can be added to the hydraulically settable mixture in a container in a batch process and with rotating mixing elements be mixed in. However, a continuous supply of hydraulically settable mixtures is not possible with a batch process. In addition, the space requirement increases with the batch process as the production volume increases.

Also known is the use of expanded pipelines, in which the additive can be mixed into the hydraulically settable mixture during conveying with rotating mixing elements arranged therein.

For example, DE 202 15662 U1 (Tachus AG) describes a mixing device in the form of an elongated tube, in which liquid concrete and accelerator can be fed in separately and, after mixing, can be passed on via a separate outlet. Mixing is done by rotating mixing elements. With the system of DE 202 15662 U1, fast-setting concrete can be produced in a continuous process, which can then be built into concrete parts using formwork. However, dynamic mixers with rotating parts, seals and drives are prone to failure and require a high level of maintenance.

Since the aggregates in concrete compositions can also be very large compared to typical pipe diameters, there is an increased risk that the aggregates will jam in the rotating mixing elements and the delivery will be blocked and interrupted abruptly (so-called "blockage").

A different approach to dosing is followed when processing shotcrete. Here, the shotcrete flows at high speed through a delivery line with an attached spray nozzle. Necessary recipe components, such as water (in the case of dry shotcrete), compressed air and additives (eg setting accelerator) are then injected directly in front of the spray nozzle and mix, among other things, during the flight from the Nozzle to the point of impact as well as on impact with the other concrete components.

In this context, EP 1 570908 A1 (Sika Technology AG) discloses, for example, a shotcrete nozzle for applying wet shotcrete or dry shotcrete. The nozzle has side openings through which an additive can be dosed into the shotcrete.

Although nozzles of this type do not have any rotating mixing elements, they are not suitable, for example, for providing formwork concrete for more massive concrete components, since the additives cannot be mixed into the concrete composition sufficiently homogeneously.

There is therefore still a need for new approaches and improved solutions which, if possible, do not have the disadvantages mentioned above.

Presentation of the invention

The object of the present invention is to provide improved devices and methods for admixing an additive into a hydraulically settable mixture. A solution should preferably be found with which an additive can be mixed as homogeneously and controlled as possible into a hydraulically settable mixture before it emerges from an outlet nozzle. The solution should be usable for different hydraulically settable mixtures and as independently as possible of the processing technique.

Surprisingly, these objects are solved by a device according to claim 1. The core of the invention is therefore a device for adding and mixing an additive into a hydraulically settable mixture, comprising a tubular cavity for passing the Pumpable mixture along an intended direction of flow, wherein a static flow-influencing element protrudes into the cavity, at which there is an opening opening into the cavity for introducing the additive.

As has surprisingly been found, the additive can be introduced directly into the inner areas of the hydraulically settable mixture through the static flow-influencing element and the opening arranged thereon and at the same time be homogeneously distributed in the mixture within a short distance. This leads to a very effective mixing. Since the flow-influencing element is a static element without moving parts, the susceptibility to errors and the maintenance effort are significantly lower compared to dynamic mixing systems. It has also been shown that the device according to the invention can be used in connection with various processing techniques. For example, it is possible to add additives to concrete compositions that are filled into formwork in a conventional manner via pipelines. In this way, for example, concrete that has been delayed for a long time can be activated with a liquid accelerator during delivery, so that the setting process is started. The device according to the invention is also suitable for admixing additives in additive manufacturing, e.g. 3D printing, of shaped bodies. The additive, such as an accelerator or a thickening agent, can be added to the delivery line directly in front of the print head. The device according to the invention has proven to be particularly advantageous since the additive can be admixed efficiently and homogeneously despite the high viscosity of the hydraulically settable mixtures usually used.

Furthermore, the device according to the invention can also be used for applying hydraulically settable mixtures in the dry or wet spraying process. The device according to the invention can thus be used extremely flexibly. Further aspects of the invention are the subject of further independent claims. Particularly preferred embodiments of the invention are the subject matter of the dependent claims.

Ways to carry out the invention

A first aspect of the invention relates to a device for adding and mixing an additive into a hydraulically settable mixture, comprising a tubular cavity for conducting the pumpable mixture along a planned flow direction, with a static flow-influencing element protruding into the cavity, at which a opening opening for introducing the additive is present.

The "hydraulically settable mixture" is a mixture containing a hydraulic binder which, in the presence of water, reacts in a hydration reaction to form solid hydrates or hydrate phases. The mixture preferably also contains aggregates, water and optional additives. The hydraulic binder can, for example, be selected from mineral and/or organic binders. For example, the binder comprises cement, lime, hydraulic lime or gypsum, each alone, as a mixture of several of the binders mentioned or in a mixture with latently hydraulic binders and/or pozzolanes. Aggregates are present in particular in the form of sand, gravel and/or aggregates. Organic binders can be, for example, epoxy or polyurethane-based binders. The hydraulically settable mixture is particularly preferably a concrete composition or a mortar composition.

An "additive" is in particular a substance which is able to change the physical and/or chemical properties of the hydraulically settable mixture. It is preferably a setting accelerator, hardening accelerator and/or a thickener.

In the present case, a “flow-influencing element” is understood to mean a body which protrudes into the cavity and influences the flow of the hydraulically settable mixture flowing through the cavity. The influencing can take place in particular in the form of an at least partial change in the direction of flow of the mixture and/or an at least partial separation of the mixture into partial flows.

The addition "static" means that the flow-influencing element is fixed immovably to the device and is not moved while the hydraulically settable mixture is being passed through. The device includes a tubular cavity. In particular, it is a cylindrical piece of pipe with an inlet and an outlet. In principle, however, the device can also have a different shape. For example, the device can be in the form of a cuboid element with a through hole.

The device consists in particular of metal and/or plastic, in particular of stainless steel.

The tubular cavity for conducting the hydraulically settable mixture is preferably in the form of a circular cylinder. However, other shapes are also possible. Thus, the tubular cavity can also have a non-circular or non-round cross-section. A fluid channel preferably runs inside the flow-influencing element, via which the additive can be conveyed, in particular from a region outside the cavity, to the opening for introducing the additive. This enables a particularly compact design.

In principle, however, it is also possible to supply the additive through a fluid channel running outside of the flow-influencing element. Particularly preferably, in the area of the flow-influencing element on an outside of the device there is a fluid inlet which communicates with the opening for introducing the additive and via which the additive can be supplied. The device can thus be connected directly to a conveying device for the additive.

According to another embodiment, however, it is also possible to provide the fluid inlet in another area and to route it to the flow-influencing element via a fluid line. The opening leading into the cavity is preferably designed in such a way that the additive can be introduced into the cavity at a distance from a wall of the cavity. In particular, a distance between the wall and the opening is 25-70%, in particular 35-50%, of the diameter of the tubular cavity.

In this way, the additive can be introduced directly into the inner region of the hydraulically settable mixture that is passed through, which leads to particularly effective mixing. In particular, the opening opening into the cavity is designed in such a way that the additive can be introduced into the cavity in a direction essentially along the longitudinal axis of the tubular cavity or at an angle thereto. In particular, the additive in a Direction which has an angle of 0 - 45 °, in particular 15 - 30 °, initiated to the longitudinal axis of the cavity. The additive can thus be added in the direction of flow or slightly obliquely, which has proven to be advantageous with regard to the fastest possible homogeneous distribution.

The opening leading into the cavity is preferably designed in such a way that the additive can be introduced into the cavity on a downstream side of the flow-influencing element. In other words, the opening opening into the cavity is preferably present on the downstream side of the flow-influencing element. In this way, on the one hand, it can be prevented that the hydraulically settable mixture is pressed into the opening as it is being conveyed through, and at the same time the pressure which is required for conveying the additive can be minimized.

However, it is also possible to arrange the opening opening into the cavity to the side of the flow-influencing element and/or in an upstream area.

If required, several openings can also be arranged in different areas of the flow-influencing element.

According to a particularly advantageous embodiment, the flow-influencing element is designed as a cylindrical socket, which protrudes into the cavity with its longitudinal axis in a direction essentially perpendicular to the longitudinal axis of the cavity or in the radial direction of the cavity. In particular, the opening leading into the cavity is present on the end face and/or the lateral surface of the cylindrical connecting piece. An arrangement in a downstream region of the lateral surface is particularly preferred. According to a further advantageous embodiment, the flow-influencing element is designed in such a way that it continuously protrudes further into the cavity along its length running in the longitudinal direction of the cavity, in particular in the direction of flow.

In particular, the flow-influencing element has a leading edge running from the upstream end to the downstream end at an angle to the direction of flow into the cavity. This has proven to be particularly advantageous with regard to the mixing effect. In addition, the risk of clogging is significantly reduced.

According to a particularly preferred embodiment, the flow-influencing element is designed as a fin, in particular as a triangular fin. A "fin" is in particular a flat one

Element understood, which has a relation to the length and the height small thickness. The thickness is preferably at most 25% of the length or the width. The fin preferably has a leading edge and an opposite trailing edge which are connected via two side surfaces, in particular two triangular side surfaces.

The fin is preferably a triangular fin. Such fins can, for example, be in the form of a flat right-angled triangle. One or more corners can be rounded and/or one or edges can be curved.

A triangular fin is arranged in particular in such a way that one of its tips protrudes into the cavity, while a side of the fin opposite the tip is arranged on the wall of the cavity. In principle, however, differently shaped fins can also be used.

In the area of the wall of the flea space, the fin is preferably aligned along the longitudinal axis of the flea space or it has an acute angle of 0-15°, in particular 1-10°, relative to the longitudinal axis of the flea space. The hydraulically settable mixture can thus be locally divided with the fin as it is passed through. At the same time, the risk of clogging in the fin area is greatly reduced.

According to a particularly preferred embodiment, the fin is at an angle to a longitudinal axis of the flea space, so that the side surfaces of the fin are at an angle to the longitudinal axis of the flea space. The inclination is preferably >0-15°, in particular 1-10°. This can further improve the mixing effect.

It has also proven to be advantageous if the fin is curved, in particular in such a way that the first side surface is configured as a concave surface and the second side surface is configured as a convex side surface.

The leading edge of the fin preferably has an angle of 20-60° to the longitudinal axis of the flea space and/or the flinter edge has an angle of 80-90° to the longitudinal axis of the flea space.

The opening for introducing the additive is preferably arranged on the flinter edge of the fin.

A cross-sectional area in the flea space of the device according to the invention, without taking into account the element(s) influencing the flow, is preferably 100-1,500 ^{cm 2} , in particular ^{500-1,200 cm 2} , especially ^{600-800 cm 2} or approx. 706 cm ² . A diameter of the flea space at the widest point is preferably 50-300 mm, in particular 80-250 mm, in particular 120-180 mm or 150 mm. The device preferably has connecting elements on the upstream side and/or on the downstream side. The connecting elements are preferably designed for connecting to pipelines and/or for connecting several devices according to the invention to one another. The connecting elements can be present, for example, in the form of flanges, clamps and/or elements of screw connections. According to an advantageous embodiment, there are at least two, in particular at least three, particularly preferably at least four, flow-influencing elements spaced apart from one another in the longitudinal direction of the flea space. Each of the flow-influencing elements is preferably a fin, in particular a triangular fin, in particular an inclined and/or curved fin, as described above.

The mixing effect can be significantly increased by several flow-influencing elements connected in series.

The at least two flow-influencing elements preferably protrude into the flea space from different radial directions.

The radial directions of the at least two flow-influencing elements are preferably at an angle of 360°/(number of flow-influencing elements) to one another. In the case of two flow-influencing elements, the angle is in particular 180°, in the case of three flow-influencing elements it is 120° and in the case of four flow-influencing elements it is 90°.

Such an arrangement benefits the mixing effect. In principle, however, irregular arrangements with other angles are also possible. In particular, the device comprises at least two, in particular at least three, preferably at least four, individual devices as described above that can be releasably connected to one another. The devices are designed in such a way that in the connected state they communicate with one another with their tubular cavities.

In this case, the device can be in the form of a set of equipment comprising at least two, in particular at least three, preferably at least four, individual devices that can be detachably connected to one another, as described above. In addition to the at least two devices according to the invention, the equipment set can contain additional connection devices for connecting the devices according to the invention to one another and/or to third-party elements. The equipment set can also contain, for example, one or more pipe sections, in particular pipe sections as are described below in connection with the arrangement according to the invention.

In the case of several devices that can be detachably connected to one another or a set of devices, the mixing effect and the addition of the additive can be flexibly adapted to specific circumstances.

Another aspect of the present invention relates to an arrangement, in particular for conveying a hydraulically settable mixture, comprising at least one device as described above, wherein a pipe section is arranged on the downstream side and/or on the upstream side, the pipe section being at least in a section has a free internal cross section which is smaller than the internal cross section of the cavity of the device according to the invention.

The free internal cross-section in the tube section at the narrowest point is preferably smaller by a factor of 0.2-0.8, in particular 0.3-0.5, compared with the cross-sectional area in the cavity of the device according to the invention, without taking into account the element(s) influencing the flow. A The diameter of the tube section at the narrowest point is preferably smaller by a factor of 0.4-0.9, in particular 0.5-0.7, compared to the cross-sectional area in the cavity of the device according to the invention. A cross-sectional area in the tube section at the narrowest point is preferably 100-600 cm ² , in particular 200-400 cm ² , in particular 300-350 cm ² or approx. 314 cm ² . A diameter of the tube section at the narrowest point is preferably 30-300 mm, in particular 50-200 mm, in particular 80-120 mm or 100 mm.

A pipe section which tapers in the direction of flow with respect to the free internal cross section is preferably connected to the downstream side. In particular, the free internal cross section in the pipe section tapers conically.

It has been shown that by combining the device according to the invention with the tapering tube section, the mixing effect can be further increased, so that a more homogeneous distribution of the additive is achieved more quickly or within a shorter distance.

The free internal cross-section in the tapering pipe section preferably decreases by a factor of 0.2-0.8, in particular 0.3-0.5, in particular over a length of 0.25-2 m, preferably 0.5-1.5 m. On the one hand, additional mixing of the additive can thus be achieved. On the other hand, the risk of clogging can be kept low.

It is also preferred if, at the same time, a second pipe section that tapers in terms of the internal cross section counter to the direction of flow is connected to the upstream side, with the second pipe section preferably tapering in a stepped manner. With regard to cross section and diameter, the second tube section is preferably dimensioned as described above. As a result, the volume flow flowing into the device according to the invention is limited, so that the risk of blockages in the area of the flow-influencing elements can be reduced.

A further aspect of the present invention relates to the use of a device according to the invention or an arrangement as described above for adding and mixing in an additive into a hydraulically settable mixture. The hydraulically settable mixture is defined as described above. In particular, it is a concrete or mortar composition.

In particular, the device or arrangement according to the invention is used in the production of shaped bodies by additive manufacturing and/or in the application of shotcrete or shotcrete.

'Additive manufacturing' refers to a process in which a three-dimensional object or a shaped body is produced through targeted spatial deposition, application and/or solidification of material.

For example, the additive manufacturing can be carried out by a print head that can be moved in at least one spatial direction, with the hydraulically settable mixture being passed through a device or arrangement according to the invention before it emerges from the print head.

Additive manufacturing can be carried out, for example, as described in EP 3558679 A1, with a device or arrangement according to the invention being connected into the supply line between pump 25 and print head 20 in addition to or instead of metering device 21 shown in FIG. 1 for adding a hardening accelerator.

A method for applying sprayed concrete or sprayed mortar can be, for example, a dry or wet spraying process. The device or arrangement according to the invention is arranged in front of the spray nozzle. In particular, the method for applying sprayed concrete or sprayed mortar can be a method as described in WO 2015/034438 A1. The sprayed concrete or sprayed mortar is sprayed into a prefabricated mesh, which serves as formwork, and built up into a shaped body.

The invention also relates to a method for adding and mixing in an additive in a hydraulically settable mixture using a device according to the invention or an arrangement as described above, the additive being introduced into the hydraulically settable mixture via the opening opening into the cavity.

The method is particularly suitable for the production of shaped bodies by additive manufacturing and/or for the application of shotcrete or shotcrete.

In particular, in the method according to the invention, the additive is metered in as a function of the volume flow of the hydraulically settable mixture conveyed through the device. In this way, the quantity of the additive can be metered precisely, so that the desired effect is achieved essentially constantly, independently of the respective delivery rate of the hydraulically settable mixture. According to a further advantageous embodiment, the additive is added with a device according to the invention containing at least two flow-influencing elements, with a first subset of the additive being added via a first flow-influencing element, while at least one further subset is added via at least one other of the flow-influencing elements. It has been shown that by adding additives in partial amounts over a number of flow-influencing elements, an even more homogeneous distribution of the additive can be achieved. It is also advantageous if the opening for introducing the additive on at least one flow-influencing element is charged with a gas, in particular air, and/or blown out after the end of the introduction of the additive. This can take place, for example, during an interruption in the delivery of the hydraulically settable mixture or after the end of the process.

In this way, it can be prevented, in particular by the gas pressure, that hydraulically settable mixture enters the opening(s) and clogs them.

Various exemplary embodiments are listed below, which are intended to explain the invention described in more detail. Of course, the invention is not limited to the exemplary embodiments described. Brief description of the figures

The drawings present to explain the exemplary embodiments show: FIG. 1 a perspective view of a device according to the invention

Device for adding and mixing an additive into a hydraulically settable mixture with a curved, triangular fin as a flow-influencing element; Figure 2 is a plan view of the downstream side of the device

Figure 1;

Fig. 3 shows a section along the line B - B of Fig. 2; 4 shows a plan view of the device from FIGS. 1-3 in the direction of the fluid inlet via which an additive can be supplied;

5 shows an arrangement with a device from FIGS. 1-4 in a schematic representation, with a pipe section that tapers conically in relation to the free internal cross section in the direction of flow being connected to the downstream end and a second pipe section being connected to the upstream end, which extends counter to the direction of flow gradually tapered;

6 shows a further arrangement comprising a set of four identically constructed devices connected to one another, as shown in FIGS. 1-4, with pipe sections connected thereto;

7a-d Variants of the invention with flow-influencing elements in the form of circular-cylindrical nozzles, trapezoidal fins and rectangular fins with differently arranged openings for introducing an additive. examples

1-4 show a device 100 according to the invention for adding and mixing in an additive into a hydraulically settable mixture. As can be seen from FIG. 1, the device 100 is in the form of a circular-cylindrical pipe section with a circular-cylindrical cavity 130 through which a hydraulically settable mixture flows along the longitudinal axis 131 (see FIG. 3), which corresponds to the intended direction of flow corresponds, can be passed through. At the downstream end 110 there is a first annular mounting flange while at the upstream end 120 there is a second annular mounting flange. The device 100 can be connected to other tubular elements via the flanges.

A triangular and curved fin 150 protrudes from the inner wall of the device 100 as a flow-influencing element into the flea space 130. An opening 160 opening into the cavity 130 for introducing an additive is arranged on the downstream flinter edge 150c of the fin 150.

The additive can be routed from the outside to the opening 160 via a fluid inlet 140 in the area of the fin 150 and a fluid channel 151 running through the fin 150 (see FIG. 3).

FIG. 2 shows a top view of the downstream end 110 of the device 100. As can be seen from FIG. 2, the fin 150 is curved along its entire height or in the radial direction. It includes a convex side 150d (visible in Figure 2) and an opposite and concavely curved side surface 150b (hidden in Figure 2; see Figure 4). The opening 160 for introducing the additive is at a distance of approximately half the diameter 132 from the wall of the circular-cylindrical cavity 130 . The diameter 132 is, for example, about 150 mm.

The triangular shape of the fin 150 can be seen in FIG. 3, which shows a section along the line BB from FIG. The fin 150 has a leading edge 150a that runs obliquely into the cavity 130 from the upstream end 120 . The angle 152 between the leading edge 150a and the longitudinal axis 131 or direction of flow is approximately 30°, for example. The fin 150 thus protrudes as a flow-influencing element continuously along its length running in the longitudinal direction 131 of the cavity 130 further into the cavity 130 . In the region of the downstream end of the fin 150, the flinter edge 150c, already shown in FIGS. 1 and 2, runs, which is approximately perpendicular to the longitudinal axis 131.

A fluid channel 151 runs through a bore in the wall of the device 100 and inside the fin 150 from the fluid inlet 140 parallel to the trailing edge 150c to the tip of the fin 150. In the area of the tip of the fin, the direction of the fluid channel 151 changes by 90°, see above that the additive 141 to be introduced can be introduced into the cavity 131 in a direction with a main component along the longitudinal axis 131 .

Fig. 4 shows a plan view of the device 100 in the direction of the fluid inlet 140. It can be seen that the fin 150 in the region of the wall of the cavity 130 runs in a direction 153 obliquely to the longitudinal axis 131 of the cavity, the direction 153 being opposite to the Longitudinal axis 131 of cavity 130 has an angle 153 of approximately 5°.

The opening 160 is designed in such a way that a flow of additive emerging from it runs in a direction 162 at an angle to the longitudinal axis 131 of the cavity. Specifically, the configuration is such that the additive can be introduced into the cavity 130 in a direction 162 which runs at an angle of approximately 30° to the longitudinal axis 131 of the cavity. 5 shows an arrangement with a device 100 from FIGS. 1-4 in a schematic representation, with a pipe section 200 tapering conically with respect to the free internal cross section in the direction of flow 133 being connected to the downstream end 110 . The pipe section 200 has a length of 1 m, for example. In the area of its upstream end, the inner diameter of the pipe section 200 corresponds to the diameter 132 of the cavity 130 of the device 100 of approx. 150 mm, while the inner diameter of the pipe section in the narrowest area or in the area of its downstream end is about 100 mm. Furthermore, a second pipe section 300 is connected to the upstream end 120 of the device 100 , which tapers in a stepped manner counter to the direction of flow 133 . In the area of its end connected to the device 100, the inner diameter of the pipe section 300 corresponds to the diameter 132 of the cavity 130 of the device 100 of approx. 150 mm, while the inner diameter of the pipe section 300 in the tapered area or in the area of its upstream end is approx. 100 mm amounts to.

6 shows a further arrangement comprising a set 400 of four structurally identical devices 100 connected to one another. The second, third and fourth of the devices according to the invention are provided with the reference symbols 100', 100", 100"'.

The four devices 100, 100′, 100″, 100″″ are detachably connected to one another via the respective flanges on the devices via clamps, so that a continuous cylindrical cavity is formed. The second device 100 ′ is rotated by 90° about the longitudinal axis relative to the first device 100 , so that the fin 150 ′ of the second device 100 ′ is at an angle of 90° to the fin 150 of the first device 100 . The third device 100" is accordingly rotated by a further 90° in relation to the second device 100' and the fourth device 100'" in turn by a further 90° in relation to the third device 100". All fins 150, 150', 150", 150 '" in the radial direction in four 90° different directions, while at the same time being spaced from each other in the longitudinal direction of the cavity.

Partial flows of an additive, e.g. a

Solidification accelerator, are introduced into the cavity or a hydraulically settable mixture passed through it. It is also possible to introduce a different additive at each of the fluid inlets 140, 140', 140", 140"'.

7a - 7d show variants of the invention with differently configured flow-influencing elements. In FIG. 7a, the flow-influencing element is a circular-cylindrical connecting piece 150.1, which has an opening 160.1 on the lateral surface in the region of its free end for introducing an additive.

In the variant from FIG. 7b, the flow-influencing element is designed as a fin 150.2 in the form of a right-angled trapezium, with the opening 160.2 for introducing the additive being present at the downstream flinter edge.

7c shows a variant with a rectangular fin 150.3. The opening 160.3 for introducing the additive is located on the lower edge of the fin, so that the fluid can be introduced into the cavity in a radial direction.

In Fig. 7d the flow influencing element is a fin 150.4 in the form of a general trapezium without right angles. In this case, the additive can be introduced via three openings 160.4. Two of the openings are at different levels on the downstream trailing edge and one opening is on the side surface.

Tests were also carried out with various configurations in order to examine the influence of the flow-influencing elements.

Experiment 1: A concrete composition was pumped through an arrangement as shown in FIG. 6 at a constant flow rate. A hardening accelerator mixed with red dye was added at a constant feed rate via the inlets 140, 140', 140", 140"' and mixed in. the like that The mixture produced was filled into a test tube closed to the tube section 200 and allowed to harden. After curing, the concrete body in the test tube was cut open transversely and the cross-sectional area analyzed optically.

Experiment 2: The procedure was the same as in experiment 1. The fins 150, 150′, 150″, 150″″ were, however, replaced by non-curved fins of the same dimensions, which were aligned parallel to the longitudinal axis and were not inclined.

Experiment 3: The procedure was the same as in experiment 1. However, the fins 150, 150', 150", 150"' have been replaced by flow-influencing elements as shown in FIG. 7a.

Experiment 4: The procedure was the same as in experiment 1. The fins 150, 150′, 150″, 150″″ were completely removed in this case, so that the accelerator was only introduced through bores in the wall of the devices 100, 100′, 100″, 100″″.

Apart from the different flow-influencing elements, all tests were carried out under identical conditions. The homogeneity of the distribution of the red dye, which represents a measure of the distribution of the hardening accelerator, was assessed visually. Specifically, the ratio of colored cross-sectional area to non-colored cross-sectional area was determined and rated on a scale from 1 (poor) to 6 (very good). Table 1 gives an overview of the results achieved. Table 1: Test results

The tests show that the addition and mixing in of an additive according to the invention with the aid of flow-influencing elements results in a significantly more homogeneous distribution of the additive in a hydraulically settable composition in comparison with conventional solutions (test 4). Flow-influencing elements in the form of fins (experiments 1 and 2) are particularly advantageous, especially if they are curved and inclined (experiment 1).

The arrangements according to the invention were also used and successfully tested in additive manufacturing processes as described in EP 3558679 A1. The arrangements according to the invention were also successfully tested for applying shotcrete in methods such as are described in WO 2015/034438 A1.

However, the exemplary embodiments shown above are not to be understood as limiting and can be modified as desired within the scope of the invention.

Claims

patent claims

1. Device (100) for adding and mixing an additive into a hydraulically settable mixture, comprising a tubular cavity (130) for conducting the hydraulically settable mixture along a planned flow direction (133), with a static flow-influencing element (150) in the cavity (130) protrudes, at which there is an opening (160) opening into the cavity (130) for introducing the additive.

2. Device according to claim 1, wherein in the cavity (130) opening

Opening (160) is designed such that the additive can be introduced into the cavity (130) at a distance from a wall of the cavity (130).

3. Device according to at least one of the preceding claims, wherein the opening (160) opening into the cavity is designed such that the additive can be introduced into the cavity (130) on a downstream side of the flow-influencing element (150).

4. The device according to at least one of the preceding claims, wherein the flow-influencing element (150) has an inflow edge (150a) running from its upstream end to its downstream end at an angle to the flow direction (133) into the cavity (130).

5. The device according to at least one of the preceding claims, wherein the flow-influencing element (150) is designed as a fin, in particular as a triangular fin.

6. Device according to claim 5, wherein the fin is inclined to a longitudinal axis (131) of the cavity (130), so that side surfaces (150b, 150d) of the fin are inclined to the longitudinal axis (131) of the cavity (130) and/or wherein the fin is curved, in particular such that a first side surface (150b) is designed as a concave surface and a second side surface (150d) is designed as a convex side surface.

7. The device according to at least one of claims 5-6, wherein a

The leading edge (150a) of the fin is at an angle of 20 - 60° to the longitudinal axis (131) of the cavity (130) and/or the trailing edge (150c) is at an angle of 80 - 90° to the longitudinal axis (131) of the cavity ( 130).

8. The device according to at least one of the preceding claims, wherein there are at least two, in particular at least three, particularly preferably at least four, flow-influencing elements (150, 150', 150", 150"') spaced apart from one another in the longitudinal direction of the cavity, with preferably the at least two flow-influencing elements project into the cavity (130) from different radial directions.

9. Device according to claim 8, wherein the radial directions of the at least two flow-influencing elements (150, 150', 150", 150"") have an angle of 360°/(number of flow-influencing elements).

10. The device (400) according to any one of the preceding claims 8 - 9, wherein the device comprises at least two, in particular at least three, preferably at least four, individual devices (100, 100', 100", 100"") that can be detachably connected to one another according to one of Claims 1 - 7 comprising, wherein the devices are designed such that they communicate with each other in the connected state with their tubular lumens.

11. Arrangement, in particular for conveying a hydraulically settable mixture, comprising at least one device (100, 400) according to any one of the preceding claims, wherein on the downstream side connected to a first pipe section (200) that tapers in the direction of flow (133) with respect to the internal cross section, with the internal cross section in the first pipe section (200) preferably tapering conically, and with a pipe section that tapers with respect to the internal cross section counter to the direction of flow (133) on the upstream side second pipe section (300) is connected, the second pipe section (300) preferably tapering in a step-like manner.

12. Use of a device according to any one of the preceding claims or an arrangement according to any one of the preceding claims in the production of shaped bodies by additive manufacturing and / or in the application of shotcrete or shotcrete.

13. A method for adding and mixing an additive into a hydraulically settable mixture, with a device (100, 400) according to any one of the preceding claims or an arrangement according to any one of the preceding claims, wherein the additive via the in the

Cavity opening opening (160) is introduced into the hydraulically settable mixture.

14. The method according to claim 13, wherein the additive is added with a device according to one of claims 8 - 9 with at least two flow-influencing elements (150, 150 ', 150"', 150'") and wherein a first subset of the additive via a first flow-influencing element (150) is added, while at the same time at least one further subset is added via at least one further of the flow-influencing elements (150', 150", 150'").

15. The method according to any one of claims 13 - 14, wherein the openings (160) opening into the cavity (130) are acted upon and/or blown out after the end of the introduction of the additive with a gas, in particular air. 1/4

140 2/4

141 3/4

figure 5

200 4/4

150.1 150.2

Fig. 7a Fig. 7b

150.3 150.4

160.4

Fig. 7c Fig. 7d