Concrete multi-stage mixing apparatus and method employing ultrasonic technology

Abstract

This invention relates to the field of concrete mixing technology, and more particularly to a multi-stage concrete mixing device and method utilizing ultrasonic technology. The multi-stage mixing device provided by this invention includes an ultrasonic mixing module, a vertical shaft mixing module, a horizontal shaft mixing module, a pipeline transport module, a fixing device, and a coordination control module. It disperses micron- and nano-scale materials in the ultrasonic reaction chamber through a pumping pipeline, disperses cement and fine aggregates through high-speed shearing of the first impeller, and disperses coarse aggregates through the second impeller. The multi-stage mixing device provided by this invention solves the problems of limited ultrasonic range and localized overheating inherent in ultrasonic mixing by using a pumping method. The combination of vertical and horizontal shaft mixing modules improves the problem of inefficient mixing zones. It achieves uniform dispersion of concrete materials from macroscopic to microscopic scales, taking into account the characteristics of different scales of concrete materials and the movement patterns of the mixture during the mixing process.

Description

Technical Field

[0001] This invention relates to the field of concrete mixing technology, and in particular to a multi-stage concrete mixing device and method using ultrasonic technology. Background Technology

[0002] Concrete is a composite material widely used in the construction industry, composed of various components including aggregates, cement, mineral admixtures, water, and additives. These components span multiple orders of magnitude, from centimeter-sized coarse aggregates to micron- and nanometer-sized ultrafine mineral admixtures. Although traditional concrete mixing methods can achieve relatively uniform dispersion of components on a macroscopic scale, they suffer from inefficient mixing zones and a lack of variety in mixing methods. On a microscopic scale, some particles still agglomerate, becoming microstructural defects in the hardened cement paste, directly affecting the intrinsic strength and durability of the concrete. Therefore, there is an urgent need for a method and equipment capable of achieving uniform mixing of concrete composite materials on both macroscopic and microscopic scales.

[0003] Chinese Patent Publication No. CN115781922A discloses a fiber-reinforced concrete preparation device, including a cylindrical mixing box. A support is fixedly connected to the bottom of the mixing box, and a slurry discharge pipe with a valve is fixedly connected to one side of the bottom of the mixing box. The top of the mixing box is open and connected to a cover. A mixing and stirring structure is rotatably connected to the inside of the cover, and a power structure is driven by the mixing and stirring structure. An ultrasonic vibration structure is rotatably connected to the top of the cover and is driven by the mixing and stirring structure. The ultrasonic vibration structure extends through the mixing and stirring structure to the inside of the mixing box. Using these structures, a method is achieved that can quickly dissolve the agglomeration phenomenon in fiber-reinforced concrete mixing using ultrasonic vibration, reducing mixing time and improving mixing effect. Furthermore, the setting of the mixing and stirring structure driving the ultrasonic vibration structure to rotate also avoids stratification caused by different solid material densities when ultrasound is applied to concrete mixing. This invention eliminates agglomeration during the mixing process of fiber-reinforced concrete by adding ultrasonic energy, reducing mixing time and improving mixing effect. However, the following problems still exist: due to the limited effective vibration range of the ultrasonic probe, the device only performs ultrasonic dispersion on a local area below the probe during the ultrasonic process, which is random and inefficient. Summary of the Invention

[0004] Therefore, the present invention provides a multi-stage concrete mixing device and method that utilizes ultrasonic technology to overcome the problems of limited ultrasonic range and local overheating in existing ultrasonic mixing technologies.

[0005] To achieve the above objectives, on the one hand, the present invention provides a multi-stage concrete mixing device and method using ultrasonic technology, comprising: an ultrasonic mixing module, a vertical shaft mixing module, a horizontal shaft mixing module, a pipeline transportation module, and a coordination control module;

[0006] The ultrasonic stirring module is used to perform cyclic ultrasonic stirring of the primary stirring material in the ultrasonic reaction chamber to disperse the primary stirring material.

[0007] The vertical shaft mixing module is connected to the ultrasonic mixing module through a circulation pipe, and is used to perform secondary mixing of the secondary mixing material through the high-speed shearing force of the first blade to break up the agglomerates formed by cement and fine aggregate.

[0008] The horizontal shaft mixing module is located directly below the vertical shaft mixing module and is connected to the slurry discharge pipe of the vertical shaft mixing module. The second blade performs three-stage mixing of the three-stage mixing material to achieve the mixing and dispersion of the various particle size components of the concrete raw materials.

[0009] The pipeline transport module is connected to the ultrasonic mixing module, the vertical shaft mixing module, and the horizontal shaft mixing module, and is used to circulate and transport the primary mixing material between the ultrasonic mixing module and the vertical shaft mixing module, and to transport the secondary mixing material from the vertical shaft mixing module to the horizontal shaft mixing module.

[0010] The coordination control module is connected to the ultrasonic stirring module, the vertical shaft stirring module, the horizontal shaft stirring module, and the pipeline transport module, respectively. It is used to determine the number of cycles and the circulation flow rate of the primary stirring material in the ultrasonic stirring module and the vertical shaft stirring module, and to determine the start time of the secondary stirring and the tertiary stirring according to the dispersion degree of the primary stirring material and the secondary stirring material, as well as the stirring parameters of the corresponding vertical shaft stirring module and the horizontal shaft stirring module.

[0011] The primary mixing material has a particle size range of micrometers to nanometers and includes admixtures and water. The secondary mixing material includes cement, fine aggregates, and uniformly dispersed primary mixing material. The tertiary mixing material includes coarse aggregates and uniformly dispersed secondary mixing material. The mixing parameters include mixing rate and mixing time.

[0012] Furthermore, the ultrasonic stirring module includes:

[0013] An ultrasonic reaction chamber, which is a cylindrical chamber, is used to hold the primary mixing material and to provide space for ultrasonic mixing;

[0014] An ultrasonic stirring rod is disposed in the ultrasonic reaction chamber to ultrasonically disperse the primary stirring material delivered to the ultrasonic reaction chamber so as to make the primary stirring material uniformly mixed.

[0015] An ultrasonic controller, which is connected to the ultrasonic stirring rod, is used to control the opening and closing of the ultrasonic stirring rod;

[0016] The diameter of the bottom circle of the ultrasonic reaction chamber is 3 to 4 times the diameter of the ultrasonic stirring rod.

[0017] Furthermore, the vertical shaft mixing module includes:

[0018] The first stirring tank is configured as a cylindrical body to provide a stirring space for the secondary stirring;

[0019] The first impeller is disposed inside the first stirring drum and the stirring shaft of the first impeller is vertically arranged. The first impeller includes blade-type impeller and ribbon-type impeller.

[0020] The feeding port is located on the side of the first mixing drum and is used as the feeding port for the primary mixing material and the secondary mixing material;

[0021] The first drive unit is connected to the first blade via a shaft and is used to drive the first blade to rotate so that the secondary mixing material is evenly dispersed.

[0022] Furthermore, the horizontal shaft stirring module includes:

[0023] The second blade is disposed inside the second stirring drum and the stirring axis of the second blade is perpendicular to the stirring axis of the first blade. The second blade includes blade-type blades and ribbon-type blades.

[0024] The second mixing drum is a closed semi-cylindrical shape composed of three planes and a semi-cylindrical curved surface. The planes include a rectangular plane and two identical semi-circular planes. The rectangular plane is connected to the two straight sides of the semi-cylindrical curved surface and is parallel to the mixing axis of the second impeller. The semi-circular plane is connected to the rectangular plane and the two curved sides of the semi-cylindrical curved surface. The second mixing drum is used to provide mixing space for the three-stage mixing material.

[0025] The inlet and outlet are located on the rectangular plane and are used to feed the third-stage mixing material into the second mixing drum through the inlet and outlet, and to output the mixed concrete mixture to the outside through the inlet and outlet.

[0026] The second drive unit is connected to the second blade via a shaft to drive the second blade to rotate so that the three-stage mixing material is evenly dispersed;

[0027] The second impeller includes blade-type impellers and ribbon-type impellers, and the distance between the rectangular plane and the stirring axis of the second impeller is greater than the rotation radius of the second impeller.

[0028] Furthermore, the pipeline transportation module includes:

[0029] The first circulation pipe connects the ultrasonic reaction chamber to the first stirring tank;

[0030] A discharge pipe is used to connect the bottom of the first mixing drum and the top of the second mixing drum to transport the secondary mixing material to the paddle discharge pipe in the horizontal shaft mixing module.

[0031] A second circulation pipe connects the outlet of the ultrasonic reaction chamber to the paddle discharge pipe;

[0032] The second circulation pipeline is equipped with a circulation pipeline valve for controlling the passage of the primary mixing material through the second circulation pipeline and an electric pump for controlling the circulation flow rate of the primary mixing material.

[0033] The discharge pipe is equipped with a discharge pipe valve located below the connection between the discharge pipe and the second circulation pipe, which allows or prevents the secondary mixing material from passing through the discharge pipe.

[0034] On the other hand, the present invention also provides a method for multi-stage mixing of concrete using ultrasonic technology, comprising:

[0035] Step S1: After adding micron- or nano-sized admixtures and water to the vertical shaft stirring module, turn on the vertical shaft stirring module to initially disperse the primary mixing material.

[0036] Step S2: Sequentially turn on the ultrasonic stirring module, the circulation pipeline valve and the electric pump to circulate the admixture and water between the vertical shaft stirring module and the ultrasonic stirring module, and perform primary stirring of the primary stirring material.

[0037] Step S3: After the primary mixing is completed, turn off the vertical shaft mixing module, ultrasonic mixing module, circulation pipeline valve and electric pump in sequence. Add cement and fine aggregate into the vertical shaft mixing module, and add the admixture that has been mixed in the primary mixing to the vertical shaft mixing module.

[0038] Step S4: Start the first drive unit to perform secondary mixing until the secondary mixing material is evenly dispersed;

[0039] Step S5: Close the first drive unit and open the paddle discharge pipe valve to allow the secondary mixing material to enter the horizontal shaft mixing module;

[0040] Step S6: After coarse aggregate is fed into the inlet and outlet, the second drive unit is activated to perform three-stage mixing of the three-stage mixing material.

[0041] Step S7: After the three-stage mixing is completed, turn off the second drive unit and remove the concrete from the inlet and outlet.

[0042] The admixtures include silica fume, slag powder, nano-silica, and carbon nanotubes.

[0043] Further, in step S1, the mass ratio of the admixture to water is 0.3% to 103.1%.

[0044] Further, in step S2, the number of cycles of the primary cyclic stirring is determined based on the mass ratio of water to admixture;

[0045] The number of cycles is inversely proportional to the mass ratio of water to admixture. When the mass ratio of admixture to water is 10% to 100%, the number of cycles LC is calculated by the following formula:

[0046]

[0047] In the formula, w is the cycle coefficient, W is the mass ratio of water to admixture, and Lmax is the maximum number of cycles.

[0048] Further, in step S2, when the mass ratio of admixture to water is 10% to 100%, the slurry viscosity of the admixture solution is determined according to the mass ratio of water to admixture.

[0049] The viscosity E of the slurry is negatively correlated with the mass ratio of water to admixtures, and is calculated using the following formula:

[0050] In the formula, f is the ultrasonic stirring frequency, P is the ultrasonic stirring power, k is the viscosity coefficient, α is the empirical coefficient, and β is the frequency coefficient.

[0051] Further, in step S2, the stirring flow rate of the primary circulating mixer is determined based on the viscosity of the slurry:

[0052] The stirring flow rate V is inversely proportional to the viscosity of the slurry;

[0053] The flow rate is controlled by an electric pump.

[0054] Compared with the prior art, the beneficial effects of the present invention are that the multi-stage concrete mixing equipment using ultrasonic technology provided by the present invention solves the problems of limited ultrasonic range and local overheating in ultrasonic mixing by pumping, improves the problem of inefficient mixing zone by combining vertical and horizontal shaft mixers, and achieves uniform dispersion of concrete materials from macroscopic to microscopic scales based on the characteristics of concrete materials of different scales and the movement law of the mixture during the mixing process.

[0055] Furthermore, this invention avoids the disadvantage of the single material movement trajectory caused by the single mixing method in traditional methods. Based on the movement law of the mixture and the characteristics of the mixer, a significant shearing motion is formed by the vertical shaft mixer and a significant convection motion is formed by the horizontal shaft mixer. The combination of the two gives full play to their respective advantages and makes up for their respective disadvantages, forming obvious shearing and convection motion in the macroscopic material mixing process, and realizing the uniform dispersion of macroscopic materials.

[0056] Furthermore, this invention improves the problem of obvious inefficient mixing zones in traditional mixing equipment by combining a vertical shaft blade mixer and a horizontal shaft ribbon mixer. Due to the objectively existing velocity gradient near the mixing shaft of the vertical shaft mixer, the mixture is difficult to mix effectively. Some materials in this inefficient zone can undergo a certain degree of shearing motion under the action of the ribbon blades of the horizontal shaft mixer, which improves the inefficient mixing zone in the vertical shaft mixer to a certain extent.

[0057] Furthermore, the ultrasonic stirring device of the present invention further enhances the physical dispersion effect by directly depolymerizing micron- and nano-scale admixtures in the ultrasonic reaction chamber through the ultrasonic cavitation effect. The designed pumping method enables the circulation of the mixture in the pipeline transportation system, while the mixture is centrally processed in the designed ultrasonic reaction chamber, thus solving the problems of limited ultrasonic range and overheating caused by excessively high local ultrasonic energy.

[0058] Furthermore, the multi-stage concrete mixing method using ultrasonic technology provided by this invention has multiple advantages. First, the admixtures and water are initially dispersed in the vertical shaft mixing module and then circulated for primary mixing, creating favorable conditions for subsequent mixing. Second, the number of cycles for primary mixing is determined by the mass ratio of water to admixtures, and the mixing flow rate is adjusted according to the viscosity of the slurry, achieving precise control of the primary mixing material and optimization of the circulating mixing process. In addition, subsequent step-by-step operations and multi-stage mixing processes help ensure uniform dispersion and quality improvement of the concrete.

[0059] Furthermore, the multi-stage concrete mixing method using ultrasonic technology provided by this invention optimizes concrete quality and improves performance by fully utilizing ultrasonic technology and the multi-stage mixing process, providing an efficient and feasible production method for the engineering and construction field. Attached Figure Description

[0060] Figure 1 This is a diagram of a multi-stage concrete mixing device that utilizes ultrasonic technology, as described in an embodiment of the present invention.

[0061] Figure 2 This is a connection diagram of a multi-stage concrete mixing device that utilizes ultrasonic technology according to an embodiment of the present invention.

[0062] Figure 3 This is a flowchart of a multi-stage concrete mixing method using ultrasonic technology, as described in an embodiment of the present invention.

[0063] Figure 4 This is a diagram of a blade-type vertical shaft stirring module according to an embodiment of the present invention;

[0064] Figure 5 This is a diagram of a ribbon-type blade horizontal shaft stirring module according to an embodiment of the present invention;

[0065] In the diagram: 1, fixed device; 2, ultrasonic stirring rod; 3, ultrasonic reaction chamber; 4, ultrasonic controller; 5, first drive unit; 6, feeding port; 7, first stirring drum; 8, first circulation pipe; 9, second circulation pipe; 10, circulation pipe valve; 11, second drive unit; 12, inlet / outlet; 13, second stirring drum; 14, discharge pipe; 15, discharge pipe valve; 16, electric pump; 17, first blade; 18, second blade. Detailed Implementation

[0066] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0067] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0068] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0069] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0070] Please see Figure 1 and Figure 2 As shown, Figure 1 This is a diagram of a multi-stage concrete mixing device that utilizes ultrasonic technology, as described in an embodiment of the present invention. Figure 2 This is a connection diagram of a multi-stage concrete mixing device using ultrasonic technology according to an embodiment of the present invention. The present invention provides a multi-stage concrete mixing device using ultrasonic technology, comprising: an ultrasonic mixing module, a vertical shaft mixing module, a horizontal shaft mixing module, a pipeline transport module, a fixing device 1, and a coordination control module;

[0071] The ultrasonic stirring module is used to perform cyclic ultrasonication on the primary stirring material in the ultrasonic reaction chamber 3 to disperse the primary stirring material at the micron or nanometer scale.

[0072] The vertical shaft mixing module is connected to the ultrasonic mixing module through a circulation pipe, and is used to perform secondary mixing of the secondary mixing material through the high-speed shear force of the first blade 17 to break up the agglomerates formed by cement and fine aggregate; it is understood that the fine aggregate includes sand.

[0073] The horizontal shaft mixing module is located directly below the vertical shaft mixing module and is connected to the paddle discharge pipe 14 of the vertical shaft mixing module. The second blade 18 performs three-stage mixing of the three-stage mixing material to achieve the mixing and dispersion of the various particle size components of the concrete raw materials.

[0074] The pipeline transport module is connected to the ultrasonic mixing module, the vertical shaft mixing module, and the horizontal shaft mixing module, and is used to circulate and transport the primary mixing material between the ultrasonic mixing module and the vertical shaft mixing module, and to transport the secondary mixing material from the vertical shaft mixing module to the horizontal shaft mixing module.

[0075] The fixing device 1 is connected to the ultrasonic stirring module, the vertical shaft stirring module and the horizontal shaft stirring module respectively, and is used to fix the ultrasonic stirring module, the vertical shaft stirring module and the horizontal shaft stirring module, and maintain the spatial placement of the ultrasonic stirring module, the vertical shaft stirring module and the horizontal shaft stirring module.

[0076] The coordination control module is connected to the ultrasonic stirring module, the vertical shaft stirring module, the horizontal shaft stirring module, and the pipeline transport module, respectively. It is used to determine the number of cycles and the circulation flow rate of the primary stirring material in the ultrasonic stirring module and the vertical shaft stirring module, and to determine the start time of the secondary stirring and the tertiary stirring according to the dispersion degree of the primary stirring material and the secondary stirring material, as well as the stirring parameters of the corresponding vertical shaft stirring module and the horizontal shaft stirring module.

[0077] The primary mixing material has a particle size range of micrometers to nanometers and includes admixtures (powdered admixtures) and water. The secondary mixing material includes cement, fine aggregates, and uniformly dispersed primary mixing material. The tertiary mixing material includes coarse aggregates and uniformly dispersed secondary mixing material. The coarse aggregates include crushed stone. The mixing parameters include mixing rate and mixing time.

[0078] Please continue reading. Figure 1 As shown, the ultrasonic mixing module in the multi-stage concrete mixing equipment using ultrasonic technology in this embodiment of the invention includes:

[0079] The ultrasonic reaction chamber 3 is a cylindrical chamber used to load the primary mixing material and to provide space for ultrasonic mixing.

[0080] The ultrasonic stirring rod 2 is located at the highest point of the fixed device 1. Its probe is set in the ultrasonic reaction chamber 3 to ultrasonically disperse the primary stirring material delivered to the ultrasonic reaction chamber 3 so that the primary stirring material is mixed evenly. It can be understood that the diameter of the ultrasonic stirring rod 2 probe is between 1 and 2 cm, and the actual effective ultrasonic range is 2 to 3 times the probe diameter (approximately 5 cm). The effective ultrasonic stirring range is also related to the viscosity of the slurry. The effective stirring range of the stirring rod decreases as the viscosity of the slurry increases.

[0081] An ultrasonic controller 4 is connected to the ultrasonic stirring rod 2 and is used to control the opening and closing of the ultrasonic stirring rod 2.

[0082] The diameter of the bottom circle of the ultrasonic reaction chamber 3 is 3 to 4 times the diameter of the ultrasonic stirring rod 2.

[0083] Please see Figure 4 The diagram shown is of a blade-type vertical shaft stirring module according to an embodiment of the present invention. The vertical shaft stirring module provided in this embodiment of the present invention includes:

[0084] The first stirring drum 7 is configured as a cylindrical body located on the fixing device 1 to provide a stirring space for the secondary stirring.

[0085] The first blade 17 is disposed inside the first stirring drum 7 and the stirring shaft of the first blade 17 is vertically arranged. The first blade 17 includes blade-type blades and ribbon-type blades.

[0086] Feed port 6 is located on the side of the first mixing drum 7 and is used as the feed port 6 for the primary mixing material and the secondary mixing material, that is, the primary mixing material and the secondary mixing material are fed into the vertical shaft mixing module through this port;

[0087] The first drive unit 5 is connected to the first blade 17 of the vertical shaft stirring module via a shaft, and is used to drive the first blade 17 to rotate so that the secondary stirring material is evenly dispersed.

[0088] The first stirring drum 7 is vertically downward and perpendicular to the ground.

[0089] Please see Figure 5 The diagram shown is of a horizontal shaft stirring module with a ribbon-type impeller according to an embodiment of the present invention. The horizontal shaft stirring module provided in this embodiment of the present invention includes:

[0090] The second blade 18 is disposed inside the second stirring drum 13 and the stirring shaft of the second blade 18 is horizontally arranged perpendicular to the stirring shaft of the first blade 17. The second blade 18 includes blade-type blades and ribbon-type blades.

[0091] The second mixing drum 13 is a closed semi-cylindrical shape composed of three planes and a semi-cylindrical curved surface. The planes include a rectangular plane and two identical semi-circular planes. The rectangular plane is connected to the two straight sides of the semi-cylindrical curved surface and is parallel to the mixing axis of the second impeller 18. The semi-circular plane is connected to the rectangular plane and the two curved sides of the semi-cylindrical curved surface. The second mixing drum 13 is used to provide mixing space for the three-stage mixing material.

[0092] The inlet and outlet 12 is located on the rectangular plane and is used to feed the three-stage mixing material into the second mixing drum through the inlet and outlet 12, and to output the mixed concrete mixture to the outside through the inlet and outlet 12.

[0093] The second drive unit 11 is connected to the second blade 18 of the horizontal shaft stirring module via a shaft, and is used to drive the second blade 18 to rotate so that the three-stage stirring material is evenly dispersed.

[0094] The second impeller 18 includes blade-type impellers and ribbon-type impellers. The stirring axis of the second impeller 18 is perpendicular to the stirring axis of the first impeller 17. The axial direction of the second stirring cylinder 13 is parallel to the ground. The distance between the rectangular plane and the stirring axis of the second impeller 18 is greater than the rotation radius of the second impeller 18.

[0095] It is understandable that the inlet and outlet 12 of the horizontal shaft mixing module share the same port, while the feed port 6 and the first discharge port of the vertical shaft mixing module are located in different positions.

[0096] Please see Figure 1 As shown, the pipeline transportation module includes:

[0097] The first circulation pipe 8 connects the ultrasonic reaction chamber 3 and the first stirring tank 7;

[0098] The bottom of the first mixing drum 7 is connected to the top of the second mixing drum 13 to convey the secondary mixing material to the paddle discharge pipe 14 in the horizontal shaft mixing module;

[0099] The discharge port of the ultrasonic reaction chamber 3 is connected to the second circulation pipe 9 of the paddle discharge pipe 14;

[0100] It is understandable that the vertical shaft mixing module, the ultrasonic reaction chamber 3 and the slurry discharge pipe are connected through the first circulation pipe 8 and the second circulation pipe 9, and the circulation pumping of the primary mixture is realized through the electric pump 16 on the second circulation pipe 9.

[0101] The second circulation pipe 9 is equipped with a circulation pipe valve 10 for controlling the passage of the primary mixing material through the second circulation pipe 9 and an electric pump 16 for controlling the circulation flow rate of the primary mixing material. It can be understood that when the circulation pipe valve 10 is opened, the primary mixing material can enter the vertical shaft mixing module through the second circulation pipe 9; when the circulation pipe valve 10 is closed, the secondary mixing material is prevented from entering the vertical shaft mixing module through the second circulation pipe 9. In practice, the circulation pipe valve 10 is opened when the primary mixing is performed, and the circulation pipe valve 10 is closed after the primary mixing is completed.

[0102] The discharge pipe 14 is provided with a discharge pipe valve 15 located below the connection between the discharge pipe 14 and the second circulation pipe 9, which is used to allow or prevent the secondary mixing material from passing through the discharge pipe 14.

[0103] In practice, when the discharge pipe valve 15 is opened, the secondary mixing material can enter the horizontal shaft mixing module through the discharge pipe 14; when the discharge pipe valve 15 is closed, the secondary mixing material is prevented from entering the horizontal shaft mixing module through the discharge pipe 14.

[0104] Please see Figure 3 The diagram shows a flowchart of a multi-stage concrete mixing method using ultrasonic technology according to an embodiment of the present invention. The present invention also provides a multi-stage concrete mixing method using ultrasonic technology, comprising:

[0105] Step S1: After adding the micron- or nano-sized admixture and water to the vertical shaft stirring module, the vertical shaft stirring module is turned on to initially disperse the primary mixing material. It can be understood that when the admixture powder is directly poured into the aqueous solution, a considerable portion of the admixture floats on the surface of the aqueous solution due to surface tension. At this stage, the vertical shaft stirring module only needs to perform low-speed stirring (preferably 100 rpm). Its actual function is to initially mix the silica fume floating on the water surface and in the water through the paddle stirring, and to drive the solution to keep the silica fume solution in motion to better realize the pumping process. There are no requirements for the stirring effect.

[0106] Step S2: Sequentially turn on the ultrasonic stirring module, the circulation pipeline valve 10 and the electric pump 16 to circulate the admixture and water between the vertical shaft stirring module and the ultrasonic stirring module, and perform primary stirring of the primary stirring material.

[0107] Step S3: After the first stage of mixing is completed, the vertical shaft mixing module, ultrasonic mixing module, circulation pipeline valve 10 and electric pump 16 are turned off in sequence. Cement and fine aggregate are put into the vertical shaft mixing module, and the admixtures that have been mixed in the first stage are put into the vertical shaft mixing module.

[0108] In implementation, the vertical shaft mixer is equipped with a conductivity sensor (connected to the coordination control module) to monitor the conductivity of the primary mixing material in real time (admixtures dissolved in the liquid affect the conductivity of the solution; when admixtures are not completely dispersed, the concentration of the solute may increase, leading to changes in conductivity). The coordination control module determines whether primary mixing has ended (after the calculated number of cycles has been completed) based on the conductivity of the primary mixing material: if the change in conductivity within a preset time is less than or equal to a preset reference value, the coordination control module determines that primary mixing has ended; if the change in conductivity within a preset time is greater than the preset reference value, the coordination control module determines that primary mixing has not ended and a second primary mixing is required.

[0109] It is understandable that the preset time is set to 15s, and the preset reference value is >0 (preferably, the preset reference value = 2%); that is, after the first-stage stirring cycle has completed the calculated number of cycles, if the change in conductivity in the last 15s is greater than 2% (that is, the lowest conductivity and the highest conductivity in the last 15s are found and recorded as σlow and σh igh respectively, (σh igh-σlow)÷σlow×100%>2%), the coordination control module determines that the first-stage stirring has not ended and a second-stage stirring needs to be performed.

[0110] During implementation, when a second primary stirring is required, the coordination control module determines the number of cycles for the second primary stirring based on the change in ballistic rate. The number of cycles is calculated as: {[(σh igh - σlow) ÷ σlow × 100%] - 2%} ÷ 2% × number of cycles; the flow rate remains constant during the second cycle. The coordination control module determines that primary stirring has ended when the change in conductivity is less than or equal to a preset reference value within a preset time.

[0111] After determining that the first-stage mixing is finished and the electric pump 16 is turned off, the coordination control module opens the feed port 6 to feed fine aggregate into the vertical shaft mixing module.

[0112] Step S4: Start the first drive unit 5 to perform secondary stirring until the secondary stirring material is evenly dispersed;

[0113] The stirring rate of the vertical shaft stirring module is adjustable from 50 r / min to 500 r / min, and the stirring time is 1 to 3 min. The stirring time and the mixing ratio are related to the equipment of the vertical shaft stirring module. Preferably, the stirring time of the vertical shaft stirring module is 3 min, and the speed is 300 rpm.

[0114] In practice, an infrared camera is also installed in the vertical shaft mixing module to determine whether the secondary mixing material is evenly dispersed. The method to determine whether it is fully mixed is to observe the formation of the suspension. During the mixing process, cement, sand, and silica fume solution will undergo particle formation (powder wrapping water droplets), particle growth (shear action releases water droplets in the particles, wetting the dry outer surface and adhering more dry powder), and particle agglomeration (the dry powder is consumed, and the outer surface of large particles becomes wet and agglomerates together). When the suspension is finally observed by the infrared camera, if no obvious agglomeration is observed (no obvious agglomeration can be understood as all agglomerates having a particle size less than or equal to the maximum particle size of the added fine aggregate), the coordination control module considers the mixing to be sufficient and the mixing to be completed.

[0115] Step S5: Close the first drive unit 5 and open the discharge pipe valve 15 to allow the secondary mixing material to enter the horizontal shaft mixing module;

[0116] After determining that the secondary mixing is completed, the coordination control module opens the discharge pipe valve 15 to allow the secondary mixing material to enter the horizontal shaft mixing module, and opens the inlet and outlet ports 12 to feed coarse aggregate into the horizontal shaft mixing module.

[0117] Step S6: After coarse aggregate is fed into the inlet / outlet 12, the second drive unit 11 is activated to perform three-stage mixing of the three-stage mixing material. In practice, the mixing speed of the horizontal shaft mixing module is adjustable from 20 r / min to 60 r / min, and the mixing time is 1 to 3 min. Preferably, the mixing speed is 300 r / min and the mixing time is 3 min.

[0118] Step S7: After the three-stage mixing is completed, turn off the second drive unit 11 and remove the concrete from the inlet and outlet 12.

[0119] The admixtures include silica fume, slag powder, nano-silica, and carbon nanotubes.

[0120] Understandably, the admixture dosage ranges from 0.1% to 2%, slag powder from 20% to 50%, silica fume from 2% to 10%, and nano-silica from 1% to 5%. The admixture dosage is the ratio of its mass to the total designed mass of the cementitious material (cement + admixture). For example, if the designed total mass of cementitious material is 100g, with 50g of slag powder, 10g of silica fume, and 40g of cement, then...

[0121] Specifically, in step S1, the mass ratio of the admixture to water is 0.3% to 103.1%.

[0122] In practice, the mass ratio of admixture to water = mass of admixture / mass of water × 100%; the water-cement ratio (mass of water / mass of designed gel material) ranges from 0.35 to 0.65.

[0123] Specifically, in step S2, the number of cycles of the primary cyclic stirring is determined based on the mass ratio of water to admixture;

[0124] The number of cycles is inversely proportional to the mass ratio of water to admixture. When the mass ratio of admixture to water is 10% to 100%, the number of cycles LC is calculated by the following formula:

[0125]

[0126] In the formula, w is the cycle coefficient, W is the mass ratio of water to admixture, and Lmax is the maximum number of cycles (10≤Lmax≤30).

[0127] It is understandable that when the mass ratio of admixture to water is <10%, the number of cycles should be calculated based on a mass ratio of admixture to water of 10%; when the mass ratio of admixture to water is >100%, the number of cycles should be calculated based on a mass ratio of admixture to water of 100%.

[0128] In practice, w∈[1,1.2], w=1, Lmax=20.

[0129] It is understandable that if the calculated value of LC includes a decimal, it will be rounded up. For example, if the calculated value of LC is 2.2, then LC = 3.

[0130] Specifically, in step S2, when the mass ratio of admixture to water is 10% to 100%, the slurry viscosity of the admixture solution is determined based on the mass ratio of water to admixture.

[0131] The viscosity E of the slurry is negatively correlated with the mass ratio of water to admixtures, and is calculated using the following formula:

[0132] In the formula, f is the ultrasonic stirring frequency, P is the ultrasonic stirring power, k is the viscosity coefficient, α is the empirical coefficient, and β is the frequency coefficient.

[0133] It is understandable that when the mass ratio of admixture to water is <10%, the slurry viscosity is calculated based on a mass ratio of admixture to water of 10%; when the mass ratio of admixture to water is >100%, the slurry viscosity is calculated based on a mass ratio of admixture to water of 100%.

[0134] It is understandable that the viscosity coefficient k∈(0.95,1.2), α>β, α∈(1,1.5], β∈[0.8,1);

[0135] Preferably, k = 1.1, α = 1.2, and β = 0.9.

[0136] Assuming f = 20kHz, P = 500W, and W = 10, then E = 1.1 × 200.9 ×500 / 10 1.2 =1.1×18.82×500÷100×15.85=6.53; The viscosity of the slurry is calculated without dimension.

[0137] Understandably, the choice of ultrasonic power depends on the type of nanomaterial, the concentration of nanomaterial, the concrete mix proportion (different concrete mixes may require different ultrasonic powers to ensure uniform dispersion of nanomaterials in the concrete), and the dispersion time (dispersion time is related to the power and range: shorter ultrasonic dispersion time requires higher power, and longer dispersion time uses lower power); ultrasonic power affects concrete performance (the impact of nanomaterial dispersion on concrete performance includes strength testing, durability testing, and evaluation of other performance indicators).

[0138] In practice, the ultrasonic power is 500-1000W, the ultrasonic frequency is 20kHz, and the stirring time is 1-3min; preferably, the ultrasonic power is 500W.

[0139] Specifically, in step S2, the stirring flow rate of the primary circulating mixer is determined based on the viscosity of the slurry:

[0140] The stirring flow rate V is inversely proportional to the viscosity of the slurry;

[0141] The flow rate is controlled by electric pump 16.

[0142] It is understandable that when the viscosity coefficient is 6, the corresponding stirring flow rate is 35s / revolution, that is, one cycle takes 35s; in practice, the flow rate = 6×35 ÷ slurry viscosity (s / revolution) = 6×35 ÷ 6.53 ≈ 32.16s / revolution ≈ 32s / revolution.

[0143] Example 1:

[0144] The ingredients are: 294g cement, 6g silica fume, 90g water, 1g water-reducing agent, 201g sand, and 648g gravel. The cement used is ordinary Portland cement, and the mixing water is tap water. The silica fume and water-reducing agent used meet the relevant standards and specifications.

[0145] Cement, silica fume, water, and water-reducing agent are added to a vertical shaft mixer in sequence and mixed at 500±5 r / min for 3 minutes. The mixture is then removed from the mixer.

[0146] Example 2:

[0147] The ingredients are: 294g cement, 6g silica fume, 90g water, 1g water-reducing agent, 201g sand, and 648g gravel. The cement used is ordinary Portland cement, and the mixing water is tap water. The silica fume and water-reducing agent used meet the relevant standards and specifications.

[0148] Cement, silica fume, water, and water-reducing agent are added to an ultrasonic mixer in sequence and mixed at 500W and 20kHz for 3 minutes. The mixture is then removed.

[0149] Example 3:

[0150] The ingredients are: 294g cement, 6g silica fume, 90g water, 1g water-reducing agent, 201g sand, and 648g gravel. The cement used is ordinary Portland cement, and the mixing water is tap water. The silica fume and water-reducing agent used meet the relevant standards and specifications.

[0151] First, add silica fume and water to the ultrasonic reaction chamber, turn on the ultrasonic device, and perform ultrasonic stirring at an ultrasonic power of 500W and an ultrasonic frequency of 20kHz to form a silica fume solution. Add the silica fume solution, water-reducing agent, and cement to the vertical shaft mixing module and stir at 300±5r / min for 3 minutes, then remove it.

[0152] The ultrasonic stirring is a single-stage cyclic stirring, with the number of cycles calculated as 3 by the calculation method provided in this invention, and the circulation flow rate is 32s / cycle.

[0153] Example 4:

[0154] The ingredients are: 294g cement, 6g silica fume, 90g water, 1g water-reducing agent, 201g sand, and 648g gravel. The cement used is ordinary Portland cement, and the mixing water is tap water. The silica fume and water-reducing agent used meet the relevant standards and specifications.

[0155] First, add silica fume and water to the ultrasonic reaction chamber, turn on the ultrasonic device, and perform ultrasonic stirring at an ultrasonic power of 500W and an ultrasonic frequency of 20kHz to form a silica fume solution. Add the silica fume solution, water-reducing agent, and cement to the horizontal shaft mixing module and stir at 300±5r / min for 3 minutes, then remove the mixture.

[0156] The ultrasonic stirring is a single-stage cyclic stirring, with the number of cycles calculated as 3 by the calculation method provided in this invention, and the circulation flow rate is 32s / cycle.

[0157] Example 5:

[0158] The ingredients are: 294g cement, 6g silica fume, 90g water, 1g water-reducing agent, 201g sand, and 648g gravel. The cement used is ordinary Portland cement, and the mixing water is tap water. The silica fume and water-reducing agent used meet the relevant standards and specifications.

[0159] First, add silica fume and water to the ultrasonic reaction chamber, turn on the ultrasonic device, and perform ultrasonic stirring at an ultrasonic power of 500W and an ultrasonic frequency of 20kHz to form a silica fume solution. Add the silica fume solution, water-reducing agent, and cement to the vertical shaft mixing module and stir at 300±5r / min for 1.5min. Then, add the mixture to the horizontal shaft mixing module and stir at 300±5r / min for 1.5min. Remove the mixture after stirring.

[0160] The ultrasonic stirring is a single-stage cyclic stirring, with the number of cycles calculated as 3 by the calculation method provided in this invention, and the circulation flow rate is 32s / cycle.

[0161] In the above five embodiments, Embodiment 1 is equivalent to performing only vertical shaft mixing, Embodiment 2 is equivalent to performing only ultrasonic mixing, Embodiment 3 is equivalent to performing ultrasonic mixing plus vertical shaft mixing, wherein the number of ultrasonic mixing cycles is determined according to the method provided by the present invention, Embodiment 4 is equivalent to performing ultrasonic mixing plus horizontal shaft mixing, wherein the number of ultrasonic mixing cycles is determined according to the method provided by the present invention, and Embodiment 5 is the preparation of concrete using the device and mixing method of the present invention.

[0162] The performance test results of the above five embodiments are shown in Table 1.

[0163] Table 1 Performance Test Results

[0164]

[0165] As can be seen from the table, the concrete prepared using the equipment and method provided by this invention exhibits better early strength than that prepared using conventional mixing processes. This is because the silica fume treated by ultrasound has finer particles, which helps to refine the particle size distribution and improve dispersibility. Due to the better particle gradation, the finer particles can fill the pores of the cement paste, fully utilizing the filling effect of silica fume. This makes the cement paste contained in the secondary mixture generated by the secondary mixing in Example 5 more compact, thus the compressive strength of the concrete is higher than that of Examples 1 to 4. Furthermore, in Example 5, because the silica fume particles treated by ultrasound have a smaller particle size and a larger specific surface area, the pozzolanic effect of silica fume in cementitious materials is better utilized, forming more hydrated calcium silicate (CSH), which adheres to silica fume particles and cement particles, resulting in improved compactness of the hardened paste and thus increasing the compressive strength of the concrete. Moreover, through Examples 1 to 5, it was found that the early strength is significantly related to the number of cycles in the primary mixing stage, the circulation flow rate, and the staged mixing in the tertiary mixing stage, proving the effectiveness of the multi-stage concrete mixing equipment using ultrasonic technology proposed in this invention.

[0166] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0167] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-stage concrete mixing device using ultrasonic technology, characterized in that, include: Ultrasonic stirring module, vertical shaft stirring module, horizontal shaft stirring module, pipeline transportation module, and coordination control module; The ultrasonic stirring module is used to perform cyclic ultrasonic stirring of the primary stirring material in the ultrasonic reaction chamber to disperse the primary stirring material. The vertical shaft mixing module, connected to the ultrasonic mixing module via a circulation pipe, is used to perform secondary mixing of the secondary mixing material using the high-speed shearing force of the first impeller to break down the agglomerates formed by cement and fine aggregate. The first stirring tank is configured as a cylindrical body to provide a stirring space for the secondary stirring; The first impeller is disposed inside the first stirring drum and the stirring shaft of the first impeller is vertically arranged. The first impeller includes blade-type impeller and ribbon-type impeller. The feeding port is located on the side of the first mixing drum and is used as the feeding port for the primary mixing material and the secondary mixing material; The first drive unit is connected to the first blade via a shaft to drive the first blade to rotate so that the secondary mixing material is evenly dispersed. The horizontal shaft mixing module is positioned directly below the vertical shaft mixing module and connected to the slurry discharge pipe of the vertical shaft mixing module. It uses a second impeller to perform three-stage mixing of the tertiary mixing material to achieve the mixing and dispersion of various particle size components of the concrete raw materials, including... The second impeller is disposed inside the second mixing drum and the mixing axis of the second impeller is perpendicular to the mixing axis of the first impeller. The second impeller includes blade-type impellers and ribbon-type impellers. The second mixing drum is a closed semi-cylindrical shape composed of three planes and a semi-cylindrical curved surface. The planes include a rectangular plane and two identical semi-circular planes. The rectangular plane is connected to the two straight sides of the semi-cylindrical curved surface and is parallel to the mixing axis of the second impeller. The semi-circular plane is connected to the rectangular plane and the two curved sides of the semi-cylindrical curved surface. The second mixing drum is used to provide mixing space for the three-stage mixing material. The inlet and outlet are located on the rectangular plane and are used to feed the third-stage mixing material into the second mixing drum and to output the mixed concrete mixture to the outside through the inlet and outlet. The second drive unit is connected to the second blade via a shaft to drive the second blade to rotate so that the three-stage mixing material is evenly dispersed; The second impeller includes blade-type impellers and ribbon-type impellers, and the distance between the rectangular plane and the stirring axis of the second impeller is greater than the rotation radius of the second impeller. The pipeline transport module is connected to the ultrasonic mixing module, the vertical shaft mixing module, and the horizontal shaft mixing module, and is used to circulate the primary mixing material between the ultrasonic mixing module and the vertical shaft mixing module, and to transport the secondary mixing material from the vertical shaft mixing module to the horizontal shaft mixing module, including... The first circulation pipe connects the ultrasonic reaction chamber to the first stirring tank; A discharge pipe is used to connect the bottom of the first mixing drum and the top of the second mixing drum to transport the secondary mixing material to the paddle discharge pipe in the horizontal shaft mixing module. A second circulation pipe connects the outlet of the ultrasonic reaction chamber to the paddle discharge pipe; The second circulation pipeline is equipped with a circulation pipeline valve for controlling the passage of the primary mixing material through the second circulation pipeline and an electric pump for controlling the circulation flow rate of the primary mixing material. The discharge pipe is equipped with a discharge pipe valve located below the connection between the discharge pipe and the second circulation pipe, which allows or prevents the secondary mixing material from passing through the discharge pipe. The coordination control module is connected to the ultrasonic stirring module, the vertical shaft stirring module, the horizontal shaft stirring module, and the pipeline transport module, respectively. It is used to determine the number of cycles and the circulation flow rate of the primary stirring material in the ultrasonic stirring module and the vertical shaft stirring module, and to determine the start time of the secondary stirring and the tertiary stirring according to the dispersion degree of the primary stirring material and the secondary stirring material, as well as the stirring parameters of the corresponding vertical shaft stirring module and the horizontal shaft stirring module. The primary mixing material has a particle size range of micrometers to nanometers and includes admixtures and water. The secondary mixing material includes cement, fine aggregates, and uniformly dispersed primary mixing material. The tertiary mixing material includes coarse aggregates and uniformly dispersed secondary mixing material. The mixing parameters include mixing rate and mixing time.

2. The multi-stage concrete mixing equipment using ultrasonic technology according to claim 1, characterized in that, The ultrasonic stirring module includes: An ultrasonic reaction chamber, which is a cylindrical chamber, is used to hold the primary mixing material and to provide space for ultrasonic mixing; An ultrasonic stirring rod is disposed in the ultrasonic reaction chamber to ultrasonically disperse the primary stirring material delivered to the ultrasonic reaction chamber so as to make the primary stirring material uniformly mixed. An ultrasonic controller, which is connected to the ultrasonic stirring rod, is used to control the opening and closing of the ultrasonic stirring rod; The diameter of the bottom circle of the ultrasonic reaction chamber is 3 to 4 times the diameter of the ultrasonic stirring rod.

3. The mixing method using the multi-stage concrete mixing equipment employing ultrasonic technology as described in claim 1, characterized in that, include: Step S1: After adding micron- or nano-sized admixtures and water to the vertical shaft stirring module, turn on the vertical shaft stirring module to initially disperse the primary mixing material. Step S2: Sequentially turn on the ultrasonic stirring module, the circulation pipeline valve and the electric pump to circulate the admixture and water between the vertical shaft stirring module and the ultrasonic stirring module, and perform primary stirring of the primary stirring material. Step S3: After the primary mixing is completed, turn off the vertical shaft mixing module, ultrasonic mixing module, circulation pipeline valve and electric pump in sequence. Add cement and fine aggregate into the vertical shaft mixing module, and add the admixture that has been mixed in the primary mixing to the vertical shaft mixing module. Step S4: Start the first drive unit to perform secondary mixing until the secondary mixing material is evenly dispersed; Step S5: Close the first drive unit and open the paddle discharge pipe valve to allow the secondary mixing material to enter the horizontal shaft mixing module; Step S6: After coarse aggregate is fed into the inlet and outlet, the second drive unit is activated to perform three-stage mixing of the three-stage mixing material. Step S7: After the three-stage mixing is completed, turn off the second drive unit and remove the concrete from the inlet and outlet. The admixtures include silica fume, slag powder, nano-silica, and carbon nanotubes.

4. The stirring method according to claim 3, characterized in that, In step S1, the mass ratio of the admixture to water is 0.3% to 103.1%.

5. The stirring method according to claim 3, characterized in that, In step S2, the number of cycles of the primary stirring is determined based on the mass ratio of water to admixture. The number of cycles is inversely proportional to the mass ratio of water to admixture. When the mass ratio of admixture to water is 10% to 100%, the number of cycles LC is calculated by the following formula: In the formula, w is the cycle coefficient, W is the mass ratio of water to admixture, and Lmax is the maximum number of cycles.

6. The stirring method according to claim 5, characterized in that, In step S2, when the mass ratio of admixture to water is 10% to 100%, the slurry viscosity of the admixture solution is determined based on the mass ratio of water to admixture. The viscosity E of the slurry is negatively correlated with the mass ratio of water to admixtures, and is calculated using the following formula: In the formula, f is the ultrasonic stirring frequency, P is the ultrasonic stirring power, k is the viscosity coefficient, α is the empirical coefficient, and β is the frequency coefficient.

7. The stirring method according to claim 6, characterized in that, In step S2, the stirring flow rate of the primary circulating mixer is determined based on the viscosity of the slurry. The stirring flow rate V is inversely proportional to the viscosity of the slurry; The stirring flow rate is controlled by an electric pump.

Images