CEMENT PREMIXER, A DEVICE FOR PRODUCING A CONCRETE MIXTURE AND METHOD FOR PRODUCING A CEMENT SUSPENSION

Description

[0001] The invention relates to a cement premixer for producing a cement suspension, as well as a device for producing a concrete mixture comprising such a cement premixer and a method for producing a cement suspension and / or a concrete or mortar mixture.

[0002] Precast concrete elements are of great importance in the construction industry due to their weather-independent production. The precast elements can be produced year-round in high quality. However, with current technologies, concrete production requires large amounts of material and energy. To ensure an efficient process for producing precast elements, the concrete must exhibit rapid strength development so that the turnaround time for the precast elements is kept as short as possible. Rapid strength development is typically achieved with highly reactive Portland cements and heat treatment of the concrete. However, highly reactive Portland cements are very expensive and have a significant carbon footprint. Additional heat treatment of concrete can be achieved using superheated steam or thermal oil directly in the formwork or in heating chambers with hot air.This consumes significant amounts of fuel, which in turn causes high CO2 emissions. Furthermore, approximately one-third of the heat produced is used to heat the steel formwork, and this portion is therefore also unavailable to accelerate the chemical reaction. This issue is addressed and discussed, among others, by Weisheit et al.; "Potential for Heat Recovery in Precast Concrete Production," 2018, i-bausil, Weimar, Germany, pp. 1146-1153, Volume 1, ISBN 78-3-00-059950-7.

[0003] Furthermore, heat treatment cannot be increased indefinitely, as excessively high treatment temperatures can lead to structural damage and significant losses in the durability of the concrete. This is explained, among others, by Stark, Jochen; Wicht, Bernd (2013): Durability of Concrete. 2nd, updated and expanded edition. Berlin: Springer Vieweg

[0004] The use of chemical accelerators allows for an increase in compressive strength. However, chemical accelerators can interact negatively with other concrete components and may not be a cost-effective replacement for heat treatment. Furthermore, the compressive strength achieved by chemical accelerators may not be sufficient at low temperatures to maintain a fast and efficient process.

[0005] DE 10 2017 206 660 A1 describes a device for producing a concrete or mortar mix directly in a concrete mixer using high-frequency vibrations. These high-frequency vibrations are transmitted into the concrete or mortar mix, which contains cement, sand, gravel, chippings, possibly other admixtures, and water.

[0006] RU2496748C1, RU2533516C1 and describe methods for mixing and ultrasonically treating water and / or cement-water mixtures. These methods differ in the selection of ultrasonic parameters and the resulting physical effects with respect to the present invention. RU2496748C1 also discloses a cement premixer according to the preamble of claim 1 and a method for providing a cement suspension according to the preamble of claim 10.

[0007] The preparation of the cement suspension on a laboratory scale is also described in "The Influence of Power Ultrasound on Setting and Strength Development of Cement Systems" by Horst-Micahel Ludwig ET AL dated January 20, 2016, pages 1-146 and in "Influence of Power Ultrasound on the Flow Properties and Early Hydration of Portland Cement Paste" MASTER'S THESIS, BAUHAUS UNIVERSITY WEIMAR, DE dated November 30, 2010, pages 1-145.

[0008] The aforementioned documents describe an intensity of up to 2.5 W / cm 2 , which leads to the region of so-called stable cavitation. This means that gas / vapor bubbles grow and oscillate around their position over many acoustic cycles. See, among others, Mason, Timothy James; Lorimer, John Phillip (2002): Applied sonochemistry. The uses of power ultrasound in chemistry and processing. Weinheim: Wiley-VCH.

[0009] In the present invention, significantly higher intensities (25 - 250 W / cm 2 ) are selected to generate so-called transient cavitation. This means that gas / vapor bubbles grow in the ultrasonic field and exist for only a few acoustic cycles before imploding, releasing large amounts of energy (heat + pressure), and thereby generating cavitation. Furthermore, RU2496748C1 and RU2533516C1 propose increasing the ambient pressure during sonication, whereas the present invention preferably operates at ambient pressure (1 bar + / - 0.1 bar).

[0010] The RU2410237C1 discloses intensities in the range of the invention application 7-70*10 4< W / m 2<, however without specifying ultrasonic amplitudes and with the aim of dispersing and / or grinding cement.

[0011] The present invention is intended to describe a cement premixer of the type mentioned at the outset and a method of the type mentioned at the outset in such a way that this cement premixer can be integrated into existing plants and, on the other hand, enables a faster, more efficient and cost-effective strength development of the concrete by means of this device.

[0012] The present invention solves the above-mentioned problem by providing a cement premixer having the features of claim 1, as well as by providing an apparatus having the features of claim 7 and by providing a method having the features of claim 10.

[0013] A cement premixer according to the invention according to claim 1 comprises a treatment tank with a treatment chamber, wherein the treatment tank has a side wall and a bottom. It also comprises at least one agitator which projects at least partially into the treatment chamber, wherein the agitator is connected to a shaft with a rotation axis. In addition, the cement premixer comprises at least one ultrasonic probe which projects at least partially into the treatment chamber. Finally, the cement premixer comprises at least one ultrasonic oscillator, e.g., a piezo element, which applies ultrasound to the at least one ultrasonic probe.

[0014] The ultrasonic probe is designed as a sonotrode and operates in the following range (values ​​refer to T=25°C and normal pressure): Intensity of the ultrasound emitted by the ultrasonic probe: 25-250 W / cm 2 . When ultrasound is introduced into a medium, the particles and the medium begin to vibrate. This vibration transfers the kinetic energy of the ultrasonic wave. The intensity (I) corresponds to the power (e.g., watts) transported per unit area. The unit is power per unit area (e.g., W / cm 2 ). Amplitude of the ultrasound emitted by the ultrasonic probe: 15-500 µm.

[0015] The amplitude (u) describes the deflection of the ultrasonic wave (e.g., in µm). At a constant frequency, higher amplitudes lead to increased intensity. The larger the amplitude, the greater the pressure differences during high- and low-pressure cycles. Frequency of the ultrasound emitted by the ultrasound probe: preferably 10-30 kHz

[0016] The frequency (f) describes the rate of oscillation at the tip of the ultrasonic probe. Since the formation, growth, and implosion of vapor bubbles is a time-dependent process, higher frequencies result in smaller cavitation bubbles. Specific energy input (into the medium - water): preferably 25-250 Ws / ml

[0017] The above values ​​can be determined, for example, electroacoustically in water using a hydrophone.

[0018] The cement premixer according to the invention has at least a first inlet opening for the supply of cement and an outlet for the flow supply of a cement suspension provided by the cement premixer into a concrete mixing device or into a concrete mixer.

[0019] Furthermore, the cement premixer according to the invention can have a control and / or regulating device which is equipped to adjust the operation of the cement premixer in the above-mentioned operating range.

[0020] The side walls and the floor enclose the treatment chamber laterally and downwards. The side walls run along the agitator's rotation axis. A lid can at least partially close off the treatment chamber at the top.

[0021] In addition to cement, water can also be supplied through the inlet opening. Alternatively, water can be supplied via a separate supply line through a separate inlet opening.

[0022] The drain can preferably have a drain opening. This is preferably located in the bottom of the treatment tank. The drain can be designed, for example, as a drain pipe with a flange connection at the end. A chute is also conceivable as a drain.

[0023] The outlet has a control device, for example a dosing device, in particular a dosing valve, by means of which the amount of cement suspension fed into the concrete mixer can be regulated. As an alternative to a valve, an adjustable flap or a lock can also be provided.

[0024] The inlet can also include a control device for regulating the amount of cement and / or water and / or other additives entering the treatment tank. This can be, for example, a solids valve or an adjustable solids flap. If the water and / or other additives are fed into the treatment tank through separate inlets, e.g., supply lines, these can also each have a separate control device.

[0025] In the cement premixer, the agitator can be coupled to a drive unit via the shaft and move within the treatment chamber by rotation.

[0026] The ultrasonic oscillator can include a controller for adjusting the amplitude of the oscillations. The amplifier, along with the amplitude adjustment and resulting intensity of the ultrasonic oscillations, allows for easy adaptation of the oscillations to different requirements in the production of various cement suspensions. This setting and the time interval of the ultrasonic treatment correspond to an energy input that can be adjusted to the volume of the cement suspension.

[0027] In a further embodiment of the cement premixer, the cement premixer has a mechanical interface, preferably a flange, via which it can be connected, preferably in a medium-tight manner, to the concrete mixer.

[0028] For this purpose, the concrete mixer can have a counterflange for detachably connecting it to the flange of the cement premixer as a flange connection. In this case, a drain pipe can be provided in the bottom of the treatment tank for transferring the produced cement slurry, for example, to a concrete or mortar mixer.

[0029] According to the cement premixer of the present invention, the at least one ultrasonic probe projects through the side wall of the treatment tank at least partially into the treatment chamber.

[0030] In a further embodiment of the cement premixer, the treatment tank has an axially symmetrical, preferably rotationally symmetrical side wall, wherein the axis of symmetry of the side wall preferably runs parallel to the axis of rotation of the agitator.

[0031] In the case of a rotationally symmetric side wall, it has a largely cylindrical shape. The axis of symmetry and the axis of rotation can coincide.

[0032] In a further embodiment of the cement premixer, the side wall has a widened portion in the half toward the bottom, which extends around the entire circumference of the side wall concentrically to the rotation axis. The widened portion extends away from the rotation axis.

[0033] In a further embodiment, the ultrasound probes are arranged in the side wall in the area of ​​the expansion.

[0034] In a further embodiment of the cement premixer, at least two ultrasonic probes, preferably three or four ultrasonic probes, project into the treatment chamber at the same angle to each other and distributed around the axis of symmetry of the side wall.

[0035] In a further embodiment of the cement premixer, at least one ultrasonic probe has a longitudinal axis and the longitudinal axis is arranged at an angle of 50° to 70°, in particular of 55° to 65° to the axis of symmetry of the side wall of the treatment tank and is oriented towards the bottom of the treatment tank.

[0036] The ultrasound probe has one end inside the treatment chamber, which is directed towards the bottom of the treatment tank.

[0037] In a further embodiment of the cement premixer, the agitator is arranged in such a way that during operation the solids are drawn in at the center of the treatment chamber.

[0038] The center of the cement premixer is located around the agitator shaft. The rotation of the shaft with the attached agitators creates a vortex. This vortex transports the material downwards in the center or along the longitudinal axis of the device to the agitators, where it rises again along the edge of the cement premixer.

[0039] This creates a flow in the medium, with the cement suspension being repeatedly guided past the sonotrodes. The size of the vortex is determined by the rotational speed and the agitator diameter and can be adapted to the dimensions of the cement premixer.

[0040] In a further embodiment of the cement premixer, it can have a control and / or evaluation unit for controlling the agitator in such a way that operation takes place at speeds of 200 revolutions per minute to 300 revolutions per minute.

[0041] To ensure good homogenization of the cement suspension, the agitator can operate in a working range of 200 revolutions per minute to 300 revolutions per minute.

[0042] In a further embodiment of the cement premixer, the agitator is designed such that, during operation, the agitator transports the cement suspension to the floor and back up again in the treatment chamber.

[0043] For this purpose, the agitator has a propeller or blade inclination of 50-55°, preferably 52-54°, ​​to promote the upflow and downflow. In another embodiment of the cement premixer, the cement premixer has a sensor for detecting the fill level of the cement premixer. The fill level can be measured using radar waves or ultrasonic waves, for example.

[0044] In a further embodiment of the cement premixer, the control and / or evaluation unit is designed to control the stirring speed of the agitator and / or to control the ultrasonic oscillator, preferably the energy input of the ultrasonic oscillator, depending on the determined fill level.

[0045] In particular, the control and / or evaluation device can control or record the specific energy input per unit volume of the cement suspension. However, this energy input can also be calculated.

[0046] In a further embodiment, the control and / or evaluation device can also control the inflow of cement, water, and, if applicable, admixtures. The inflow of water can be controlled, for example, by the level measurement in the treatment tank.

[0047] In a further embodiment, the control and / or evaluation device can also control the flow of the cement suspension, for example as a function of the energy input per unit volume of the cement suspension.

[0048] The invention also includes a device for producing a concrete mixture comprising a concrete mixer and a cement premixer according to the invention.

[0049] The cement premixer can be fluidically connected to the concrete mixer, preferably by a flange connection between an outlet of the cement premixer and an inlet of the concrete mixer.

[0050] The connection can be made mechanically, whereby the connection is ensured, for example, by the fit of the pipes.

[0051] In a further embodiment of the device, the device has at least one of the following elements: a first cement container, a second cement container, a water tank and / or an additive container, wherein the inlet is designed as an inlet pipe or inlet shaft which is detachably connected, preferably by means of a flange connection, to at least a first cement container and / or a water tank and / or an additional container of the device.

[0052] In a further embodiment of the device, the device comprises a dosing device between the cement premixer and the concrete mixer, which regulates the dosage of the cement suspension depending on the supplied amount of sand, gravel or chippings.

[0053] The amount of sand, gravel, or chippings (aggregate) added can be measured by sensors or by the feed time when the valve is open. A mass flow sensor or weighing belt can also measure the corresponding amount of aggregate.

[0054] The dosing device is located between the outlet of the cement premixer and the inlet of the concrete mixer.

[0055] The concrete mixer can also be equipped with ultrasonic probes, which can introduce ultrasonic vibrations into the concrete or mortar mixture.

[0056] The invention is also based on a method for providing a cement suspension according to claim 10, which comprises at least the following steps: Providing cement, water and optionally at least one additive in a treatment tank having a treatment chamber, Mixing by means of at least one agitator protruding at least partially into the treatment chamber to produce a cement suspension, wherein the agitator is connected to a shaft with a rotation axis, Transferring ultrasonic vibrations to the cement suspension by means of at least one ultrasonic probe protruding at least partially into the treatment chamber Discharge of the cement suspension via an outlet for further processing, in particular into a concrete mixer, The emitted ultrasound has an intensity of 25-250 W / cm2 and an amplitude of 15-500 µm.

[0057] The addition of admixtures is optional. When preparing the cement slurry, admixtures can be omitted; in this case, only cement and water are provided.

[0058] In particular, in the process for producing a cement suspension, cement, water and optionally additives are suspended in a cement premixer according to the invention.

[0059] In particular, the cement suspension contains from 50 parts by weight to 80 parts by weight of cement from 20 parts by weight to 40 parts by weight of water from 0 to 10 parts by weight of admixture based on the total mass of the cement suspension, whereby all components in the cement suspension add up to 100 parts by weight.

[0060] The aforementioned admixtures are considered concrete admixtures. These are liquid, powdered, or granular substances that are added to the concrete during mixing in small quantities, relative to the cement content. They influence the properties of the fresh or hardened concrete through chemical and / or physical effects. In concrete according to DIN EN 206-1 / DIN 1045-2 (in the current version as of July 2019), only concrete admixtures according to DIN EN 934-2 (in the current version) or concrete admixtures with general building authority approval may be used. Aggregates are generally not considered concrete admixtures.

[0061] In particular, in the process according to the invention, the agitator is operated at a speed of 50 revolutions per minute to 500 revolutions per minute.

[0062] The ultrasonic probes transmit ultrasound in the frequency range from 16 kHz to 30 kHz, especially in the frequency range from 18 kHz to 22 kHz, into the cement suspension.

[0063] The concrete or mortar is produced in particular using a combination of the cement premixer according to the invention with a concrete mixer.

[0064] The process can be operated either in a batch or continuous process. In the batch process, the components are added to the treatment tank, mixed using ultrasound and stirring to form an activated cement suspension, and then transferred, for example, to a concrete mixer. In the continuous process, the components are continuously added to the treatment tank, and the process is operated in such a way that the activated cement suspension can be continuously withdrawn from the cement premixer and transferred, for example, to the concrete mixer.

[0065] The cement premixer according to the invention enables particularly efficient homogenization and physical and chemical activation of the cement binder. Since the ultrasonic treatment in the cement premixer is limited to the components cement, water, and optionally admixtures, the energy generated by high-frequency ultrasonic vibrations can be used directly to activate the cement binder. This enables significantly improved utilization of the input energy compared to the use of ultrasonic vibrations on a mixture of cement, water, additives, and chemically inactive sand, gravel, or chippings. The reactive part of the concrete, cement and water, makes up only 20-35% of the concrete, while the chemically inactive part, sand, gravel, and chippings, makes up the remaining portion. Therefore, with the device according to the invention, the energy is applied to a much smaller proportion of materials and is therefore used much more efficiently.In addition, the production of the cement suspension in the cement premixer enables a significantly better degree of mixing to be achieved compared to conventional methods.

[0066] By improving the activation of the reactive part of the concrete and homogenizing the cement slurry in the cement premixer, a significant reduction in cement content can be achieved. Furthermore, the heat treatment time can be drastically reduced. For many applications, heat treatment can be omitted entirely.

[0067] In addition, the use of the cement premixer according to the invention accelerates concrete hardening and improves the workability (processing properties) of the concrete.

[0068] The cement premixer according to the invention also has the advantage of being very easy and cost-effective to integrate into an existing concrete mixing plant as an add-on module without great effort. The arrangement of the inlet opening for the supply of cement (from the cement scale) and, if necessary, water, as well as the outlet for the flow line for the discharge of the finished cement suspension, is particularly suitable for such integration. The mechanical interface, preferably a flange, further enhances efficient integration.

[0069] By using the fill level measurement, the inflow quantity of cement and / or water can be determined via the change in the fill level.

[0070] The combination of ultrasonic probes and agitator has proven particularly advantageous. Cement and water require significantly higher mixing intensities for complete disintegration than the concrete aggregate. Therefore, a synergistic interaction of the agitator and ultrasonic vibrations was demonstrated to produce an activated cement suspension.

[0071] The agitator according to the invention, especially in combination with the introduction of ultrasonic energy, enables a relatively low speed to generate a homogeneous suspension. This leads to lower power consumption and reduced wear on the agitator.

[0072] As can be seen from the preceding description, the present invention can be used for various applications in the field of concrete and mortar production. Accordingly, the present invention opens up a wide range of possible uses and applications, for example in the production of precast concrete elements. The variants and features mentioned and described here can also be implemented in combinations of two or more variants or features, and these combinations are also encompassed by the present invention, provided such combinations are not mutually inconsistent and do not exceed the scope of the appended claims.

[0073] An embodiment of the invention will now be described in more detail with reference to the accompanying drawings.

[0074] It shows Fig. 1a schematic cross-sectional view of an embodiment of the cement premixer according to the present invention; Fig. 2 shows a top view of the embodiment from Fig. 1 ; Fig. 3 shows a schematic representation of concrete production using a conventional method, and Fig. 4 shows a schematic representation of concrete production according to an embodiment of the present invention.

[0075] The following definition applies to the entire further description: If reference numbers are included in a figure for the purpose of graphic clarity, but are not explained in the immediately associated descriptive text, reference is made to their mention in previous figure descriptions.

[0076] As in Fig. 1As can be seen, the cement premixer 1 comprises a treatment tank 2, which has a treatment chamber 20. The treatment chamber 20 is delimited laterally by a rotationally symmetrical side wall 21 and downwards by a floor 22. At the top, the treatment chamber is closed by a cover 24. An agitator 3 with a shaft 30 projects into the treatment chamber 20, with the shaft projecting into the treatment chamber through an opening in the cover 24.

[0077] In this embodiment, the side wall 21 has an outward extension 25 in the lower half. Four ultrasound probes 4 are mounted in this area.

[0078] In this embodiment, the agitator 3 has two agitators (3.1, 3.2) attached to the shaft 30. The stirring blades of the agitators (3.1, 3.2) are spaced such that they do not touch the ultrasonic probes 4. The shaft 30 is set in rotation via the turntable by an external drive 5.

[0079] The shaft has a rotation axis 31, which coincides with the axis of symmetry 23 of the side wall 21. The extension 25 is arranged concentrically to the axis of symmetry 23 outwards (away from the axis of symmetry 23).

[0080] The ultrasound probes 4 are arranged laterally at an angle of 60° to the vertical axis of symmetry 23 of the side wall 21 and are directed downwards towards the floor 22.

[0081] In this embodiment, a control and / or evaluation unit 9 records the parameters fill level, energy input by the ultrasonic probes, and added water quantity by the water flow meter 64. It controls the drive 5 for the agitator 3 (adjusting the rotational speed of the agitator 3), the ultrasonic oscillators 42 in terms of amplitude and frequency of the ultrasound (the energy input is determined by the control and / or evaluation unit 9), the solids valve 61, the water control valve, and the discharge of the suspension via the dosing valve 71.

[0082] Furthermore, the lid 24 contains an inlet opening 60 into which a pipe 6 for the inflow of solid material extends. This is controlled by the solid material valve 61. In this embodiment, cement is added, and the addition of the cement is controlled by the solid material valve 61. A water inlet line 62 for water is arranged through the side wall 21. Thus, water can be added via the water control valve 63 to create the cement suspension. The amount of water added is determined in this embodiment by the water flow meter 64.

[0083] The fill level sensor 8 determines the fill level within the treatment chamber 20. This fill level measurement can be used, for example, by the control and / or evaluation unit as a basis for controlling the addition of water.

[0084] Located in the bottom 22 of the treatment tank 2 is an outlet 70 for the flow line 7 for discharging the finished cement slurry to the concrete mixer. The discharge of the cement slurry is regulated via the dosing device 71 depending on the specific energy input per unit volume. The outlet line 7 is provided with a flange 72, which allows the outlet line 7 to be quickly and easily connected to a concrete mixer.

[0085] Fig. 2 shows a top view of the embodiment of Fig. 1 , whereby the arrangement of the four ultrasound probes 4 at an angle of 90° to each other in the side wall 21 is particularly visible. A view into the treatment chamber 20 shows that the ultrasound probes 4 are directed towards the axis of symmetry 23 of the side wall 21.

[0086] A flange can be coupled to the drive by means of mounting holes to enable the drive of the shaft 30 and thus the agitator 3.1 and 3.2.

[0087] Fig. 3 This diagram shows a schematic of the conventional method. In a concrete mixer 100, water is added from the water inlet 200, admixtures from the admixture tank 300, cement from the first or second cement tanks 400 and 500, and aggregate (sand, gravel, and / or chippings) from the corresponding tanks 600, 700, and 800. The components are mixed directly in the concrete mixer to produce a concrete mix.

[0088] In contrast to this conventional procedure, in the process according to the invention, which is shown schematically in an embodiment in Fig. 4As shown, a cement suspension is produced separately in the cement premixer 1. Water from the water inlet 200 and cement from the cement tanks 400 and / or 500, as well as any admixtures from the admixture tank 300, are processed into a cement suspension in the cement premixer. This cement suspension is then transferred from the cement premixer 1 to the concrete mixer 100. The concrete mixture is then produced in the concrete mixer by adding the aggregate from the corresponding tanks 600, 700, and 800, which can then be further processed.

[0089] The combination of the cement premixer 1 and the concrete mixer 100 forms the device 1000 for producing a concrete mixture.

[0090] The preparation of the activated cement suspension can be carried out either in a batch process or in a continuous process. Example

[0091] A concrete was produced according to the method of the invention for producing a cement suspension.

[0092] A cement premixer according to the invention on a laboratory scale as in Fig. 1 shown with a diameter of 400 mm up to 493 mm at the widest point and a total height of 550 mm is distributed with 4 ultrasonic probes (sonotrodes) at a 90° angle to each other around the symmetry axis of the treatment tank.

[0093] The treatment room contains 45 kg of cement, 20 liters of water and 0.5 kg of flow agent (addition).

[0094] The agitator operates at a speed of 250 revolutions per minute. Vibrations in the low ultrasonic range of 20 kHz are transmitted into the treatment chamber via the sonotrodes.

[0095] By using ultrasonic treatment and the mixing tool, a fast and efficient homogenization of the cement suspension is achieved within less than 180 seconds.

[0096] The resulting cement slurry is transferred to a concrete mixer, where 225 kg of aggregate is added and the concrete is mixed.

[0097] The flowability of this concrete is significantly increased compared to conventional manufacturing methods, and the early strength is significantly improved. This leads to decisive advantages, especially in the production of precast concrete elements, and precast elements of higher quality that can be produced in a shorter time. List of reference symbols

[0098] 1 Cement premixer 2 Treatment tank 20 Treatment chamber 21 Side wall 22 Floor 23 Axis of symmetry 24 Lid 25 Side wall extension 3 Agitator 3.1 First agitator 3.2 Second agitator 30 Shaft 31 Rotation axis 32 Drive disk 33 Mounting holes 4 Ultrasonic probe (sonotrode) 41 Longitudinal axis of the ultrasonic probe 42 Ultrasonic oscillator 5 Drive 6 Inlet (solids inlet for cement) 60 Inlet opening 61 Solids valve 62 Water inlet line 63 Water control valve 64 Water flow meter 7 Flow inlet 70 Outlet 71 Dosing device 72 Flange 8 Fill level sensor for the fill level in the cement premixer 9 Control and / or evaluation unit 100Concrete mixer 200Water inlet 300Additive tank 400Cement tank 500Second cement tank 600Sand tank 700Gravel tank 800Gravel tank 1000Device

Claims

1. Cement premixer (1), comprising - a treatment container (2) having a treatment space (20), wherein the treatment container (2) comprises a side wall (21) and a bottom (22), - at least one stirring unit (3; 3.1, 3.2) which projects at least partially into the treatment space (20), wherein the stirring unit (3; 3.1, 3.2) is connected to a shaft (30) having an axis of rotation (31), - at least one ultrasound probe (4) which projects at least partially into the treatment space (20), - at least one ultrasonic oscillator (42) which applies ultrasound to the at least one ultrasonic probe (4), wherein the cement premixer (1) has at least a first introduction opening (60) for the supply of cement and an outlet (70) for the flow supply line (7) of a cement suspension provided by the cement premixer (1) into a concrete mixer, characterized in, that the cement premixer has a control and / or evaluation unit (9) and for adjusting the emitted ultrasound with an intensity of 25-250 W / cm2 and an amplitude of 15-500 µm and that the ultrasonic probe is designed to emit an ultrasound with an intensity of 25-250 W / cm2 and an amplitude of 15-500 µm.

2. Cement premixer (1) according to claim 1, characterized in that the at least one ultrasonic probe projects at least partially into the treatment space (20) through the side wall (21) of the treatment container (2).

3. Cement premixer (1) according to claim 1 or claim 2, characterized in that the treatment container (2) has an axially symmetrical, preferably rotationally symmetrical side wall (21), wherein the axis of symmetry (23) of the side wall (21) preferably extends parallel to the axis of rotation (31) of the stirring unit (3; 3.1, 3.2) and wherein the side wall (21) has an extension (25) in the half towards the bottom (22), which extension (25) extends around the entire circumference of the side wall (21) concentrically to the axis of symmetry (23) and wherein the ultrasonic probes (4) are arranged in the area of the widening (25) in the side wall.

4. Cement premixer (1) according to one of the preceding claims, characterized in that at least two ultrasonic probes (4), preferably three or more ultrasonic probes (4), project into the treatment space (20) distributed at the same angle to one another about the axis of symmetry (23) of the side wall (21).

5. Cement premixer (1) according to one of the preceding claims, characterized in that the at least one ultrasonic probe (4) has a longitudinal axis (41) and the longitudinal axis (41) is arranged at an angle of 50° to 70°, in particular of 55° to 65° to the axis of symmetry (23) of the side wall (21) of the treatment container (20) and is aligned in the direction of the bottom (22) of the treatment container (2).

6. Cement premixer (1) according to one of the preceding claims, characterized in that the cement premixer (1) comprises a level sensor (8) for detecting the level of the cement premixer and that the control and / or evaluation unit (9) is designed to control the agitation speed of the stirring unit and / or to control the ultrasonic oscillator, preferably the energy input of the ultrasonic oscillator, as a function of the determined filling level.

7. Device (1000) for producing a concrete mix, comprising a concrete mixer (100) and a cement premixer (1) according to one of the preceding claims.

8. Device (1000) according to claim 7, characterized in that the cement premixer (1) is fluidically connected to the concrete mixer (100), preferably by a flanged connection (72) between an outlet (60) of the cement premixer (1) and an inlet of the concrete mixer (100).

9. Device (1000) according to claim 7 or 8, characterized in that the device comprises at least one of the following elements: a first cement container (400), a second cement container (500), a water inlet (200), and / or an admixture container (300), wherein the inlet (6) is formed as an inlet pipe or inlet shaft, which is detachably connected, preferably by means of a flange connection, to at least a first cement container (400) and / or a water tank (200) and / or an admixture container (300) of the device (1000).

10. Method for providing a cement suspension, comprising the following steps: - providing cement, water and optionally at least one admixture into a treatment container (2) having a treatment space (20), - mixing by means of at least one stirring unit (3) projecting at least partially into the treatment space (20) to produce a cement suspension, wherein the stirring unit (3) is connected to a shaft (30) with an axis of rotation, - transmitting ultrasonic oscillations by means of at least one ultrasonic probe (4) projecting at least partially into the treatment space (20), - discharging the cement suspension via an outlet (60) for further processing, in particular in a concrete mixer, characterized in, that the emitted ultrasound has an intensity of 25-250 W / cm2 and an amplitude of 15-500 µm.

11. Method for providing a cement suspension according to claim 10, characterized in that the discharging of the cement suspension is performed according to a specific energy input per unit volume of the cement suspension.

12. Method for providing a cement suspension according to claim 10 or 11, characterized in that the cement suspension is - from 20 parts by weight to 80 parts by weight cement - from 20 parts by weight to 80 parts by weight water - from 0 to 10 parts by weight admixture based on the total mass of the cement suspension, with all components in the cement suspension adding up to 100 parts by weight.

13. Method according to one of claims 10 to 12, characterized in that the stirring unit (3; 3.1, 3.2) is operated at a speed of 50-500 revolutions per minute, preferably 200-300 revolutions per minute.

14. Method according to one of claims 10 to 13, characterized in that the ultrasonic probes transmit ultrasound in the frequency range from 16 kHz to 30 kHz, in particular in the frequency range from 18 kHz to 22 kHz, into the cement suspension.

15. Method for mixing concrete or mortar using a device according to one of claims 7 to 9.