Fine production method of ultra-high performance concrete premix

Abstract

The present application relates to the technical field of concrete, more particularly, to a fine production method of ultra-high performance concrete premix.The fine production method of ultra-high performance concrete premix comprises the following steps: S1, raw material selection and mix proportion design; S2, raw material preparation; S3, raw material feeding into a tank; S4, raw material metering; five scales are arranged for classified metering of each material, namely, a first scale, a second scale, a transition bin scale, a rotary vibrating screen scale and a manual scale; S5, raw material feeding; S6, variable frequency stirring; the stirring is divided into three stages, namely, low frequency 30Hz-50Hz, high frequency 50Hz and low frequency 50Hz-30Hz; S7, fly knife start-stop; S8, unloading after completion of stirring; S9, finished product storage and transportation.The method not only significantly improves the strength, toughness, durability and other performances of UHPC premix, but also realizes efficient, energy-saving, continuous and low-loss production process, and has outstanding industrial application value.The present application is mainly applied to fine production of ultra-high performance concrete premix.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and more specifically, to a refined production method for ultra-high performance concrete premixes. Background Technology

[0002] Currently, the production of ultra-high performance concrete (UHPC) premixes mainly relies on traditional premixing plants, which suffer from significant bottlenecks restricting their quality and efficiency. Firstly, the predominantly intermittent operation, with construction breaks between cycles, prevents automated continuous production, leading to low efficiency and batch-to-batch contamination. Secondly, it has poor adaptability to diverse formulations, particularly lacking special treatment for key performance-determining fines (such as silica fume and nanomaterials), making precise feeding and thorough uniform dispersion difficult. Thirdly, inadequate environmental protection measures result in significant losses of fines during production and dust removal, leading to low fines recycling rates and directly disrupting the particle size distribution of the premix design, resulting in unstable final product performance. These problems severely impact the level of refined control and large-scale application of UHPC premixes, necessitating the development of a novel construction method that enables continuous production, refined processing of key fines, and effective fines recycling. Summary of the Invention

[0003] To overcome the shortcomings of the existing technology, this invention provides a refined production method for ultra-high performance concrete premixes. This method realizes centralized, continuous, and intelligent production of ultra-high performance concrete premixes in factories, achieving a closed continuous production mode of "raw material lifting into tanks + automatic batching and metering + temporary storage + continuous production." The highly intelligent mechanized production greatly reduces manpower input and basically realizes continuous production operations.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A refined production method for ultra-high performance concrete premix includes the following steps:

[0006] S1. Raw Material Selection and Mix Design: Analysis of particle morphology, particle size distribution, and physicochemical characteristics of UHPC matrix materials at the microscale. Based on the experimental test results of each matrix material, its unique properties are compared with existing specifications to identify the quality of raw materials. A combination of qualitative and quantitative analysis methods is used. On the one hand, a 10,000x industrial electron microscope is used to obtain the microscopic geometric morphology of the matrix materials, qualitatively comparing and selecting matrix materials, making it easier to distinguish between good and bad quality. On the other hand, a laser particle size analyzer is used to obtain the particle size distribution of the matrix materials and quantitatively compare and select matrix materials based on the closeness of the synthetic gradation of the constituent materials to the target gradation.

[0007] S2. Raw material preparation: The raw material storage warehouse needs to be divided into areas and stacked reasonably. Moisture-proof bags should be placed in the corners of the warehouse to prevent the materials from getting damp and deteriorating.

[0008] S3. Raw material loading: During the raw material loading process, one vehicle is required to assist in the loading and unloading process using a gantry crane equipped at the loading port.

[0009] S4. Raw material metering: All raw materials are conveyed to the metering scales via screw conveyors. Five scales are set up to classify and meter each material, namely scale No. 1, scale No. 2, transition bin scale, vibrating screen scale, and manual scale. After the materials are metered by scale No. 1, a second lifting operation is performed, in which the metered materials are conveyed to elevator No. 3 via screw conveyors, so that the materials are transferred from scale No. 1 to transition bin scale for use.

[0010] S5. Raw material input: Steel fiber is simultaneously added and mixed using a process.

[0011] S6. Variable frequency mixing: Mixing is achieved by equipping a variable frequency heavy-duty mixer. The mixing is divided into three stages: low frequency 30Hz-50Hz → high frequency 50Hz → low frequency 50Hz-30Hz.

[0012] S7, Flying Knife Start-Stop: Utilizes three 3000RPM high-speed flying knives;

[0013] S8. Discharge after mixing: After mixing is complete, open the discharge hopper door to discharge the material into the premix storage tank;

[0014] S9. Finished material storage and transportation: Premixed materials shall be packaged in drums or ton bags.

[0015] In step S1, the fiber used is copper-plated rust-proof steel fiber. The fiber length is measured using a vernier caliper. The main fiber length is 12mm-16mm, and the auxiliary short fiber length is 7mm-9mm. The equivalent diameter of the fiber is measured using a micrometer. The equivalent diameter of the main fiber should be 0.20±0.02mm, and the equivalent diameter of the auxiliary fiber should be 0.12±0.005mm. The aspect ratio of both the main fiber and the auxiliary fiber is required to be 60-70.

[0016] In step S2, cement is stored directly in tanks, ensuring that cement is delivered as needed during production. Silica fume and fly ash are stored and transported in ton bags with inner moisture-proof films. Semi-density silica fume is selected for delivery, and its particle size and microstructure are tested and analyzed upon arrival. After passing the tests, it is stored in the warehouse, with each bag placed on a forklift pallet for easy transport. All quartz sand is delivered and stored in ton bags. Its particle size is tested and analyzed upon arrival, and it is stored in the warehouse after passing the tests. Steel fiber is packaged in moisture-proof paper bags, with 5 bags stacked per layer, 12 layers per pallet, and a total of 60 bags per pallet, all wrapped with a moisture-proof film.

[0017] In step S3, the ultra-high performance concrete premixing plant is designed with two elevators for feeding raw materials into the tank. The first elevator is responsible for lifting aggregates and effectively feeding powder by controlling the opening of the elevator's inlet and outlet valves, so that different materials are fed into the tank accordingly. The second elevator is responsible for feeding ultrafine powders, including silica fume and fly ash. The feeding of steel fibers is achieved through a conveyor belt set on one side of the mixing tank.

[0018] In step S4, the first scale is mainly responsible for measuring the three types of quartz sand and cement. To effectively control the measurement accuracy of each material and reduce losses during the secondary lifting process, the measurement sequence of the first scale is set as coarse sand → fine sand → cement → medium sand. The transition bin scale is responsible for re-measuring the various raw materials measured by the first scale after transfer to ensure complete transfer. The second scale is responsible for measuring the two types of ultrafine particle materials. This scale is directly connected to the mixing tank to ensure that the materials can be directly put into the mixing pot after measurement, so as to reduce the mass loss of the core materials after weighing and ensure a high degree of consistency between the material measurement and the mix ratio. The vibrating screen scale is responsible for the addition of steel fibers and can be precisely measured according to the mix ratio requirements, with an accuracy of ±0.1%. The manual scale is a reserved scale. Given the variability of the material mix ratio, the reserved manual scale is directly connected to the mixing tank to accurately add the core raw materials, so as to ensure a high degree of consistency between the core material measurement and the mix ratio.

[0019] In step S5, the materials in the transition silo are first added, namely various aggregates and cement, then steel fibers are added, and finally the materials in the second silo are added, namely silica fume and fly ash.

[0020] In step S6, low-frequency stirring is used during the material addition process to improve energy efficiency; after all materials are added, high-frequency stirring is performed to ensure that the materials are mixed evenly in a short time; after stirring is completed, low-frequency stirring is resumed to save energy and improve efficiency.

[0021] In step S7, during the stirring process, the flying knife starts 10 seconds after the initial addition time of each material. The cutting time of the flying knife is calculated based on the stirring time, and the flying knife stops operating 10 seconds before the stirring is completed.

[0022] In step S8, the unloading time is 10-12 seconds. After the silo door is completely closed, the next batch of mixing begins, forming continuous automated production.

[0023] In step S9, when using a premixed material container, the plastic container of the premixed material is covered with a lid and sealed with two layers of self-adhesive film; when using a ton bag packaging method, after the ton bag opening is sealed, an outer film moisture-proof bag is placed over it to prevent the material from getting damp.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] Microscale analysis, employing an industrial electron microscope combined with a laser particle size analyzer, is used for both qualitative and quantitative screening of the matrix materials. This ensures precise identification of raw material quality and guarantees that the source materials meet high-performance requirements. A five-level metering system, consisting of a No. 1 weighing scale, a No. 2 weighing scale, a transition bin weighing scale, a vibrating sieve weighing scale, and a manual weighing scale, has a clear division of labor, reducing cross-contamination and metering interference. The transition bin weighing scale effectively monitors transfer losses, ensuring accurate total quantities. The No. 2 weighing scale is directly connected to the mixing tank, and the manual weighing scale is designed to ensure "zero loss" of core ultrafine powders after metering, maximizing the consistency between the mix proportions and the design. The system also employs "simultaneous steel fiber addition" and "final addition of ultrafine powders." The "release" process sequence completely avoids the agglomeration problem caused by premature coating of ultrafine powder with steel fibers, significantly improving the uniformity of fiber dispersion and interfacial bonding in the matrix, thereby optimizing the toughness and crack resistance of concrete. The mixing method of low-frequency addition → high-frequency mixing → low-frequency unloading can efficiently disperse fiber bundles and powder clumps, while avoiding damage to fibers or waste of energy due to over-mixing. Through refined and intelligent process design and strict material control, this method not only significantly improves the strength, toughness, and durability of UHPC premix, but also achieves high efficiency, energy saving, continuity and low loss in the production process, and has outstanding industrial application value. Attached Figure Description

[0026] Figure 1 This is a production process diagram for the present invention. Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0029] like Figure 1 As shown, a precision production method for ultra-high performance concrete premix includes the following steps:

[0030] S1. Raw Material Selection and Mix Design: Analysis of particle morphology, particle size distribution, and physicochemical characteristics of UHPC matrix materials at the microscale. Based on the experimental test results of each matrix material, its unique properties are compared with existing specifications to identify the quality of raw materials. A combination of qualitative and quantitative analysis methods is used. On the one hand, a 10,000x industrial electron microscope is used to obtain the microscopic geometric morphology of the matrix materials, qualitatively comparing and selecting matrix materials, making it easier to distinguish between good and bad quality. On the other hand, a laser particle size analyzer is used to obtain the particle size distribution of the matrix materials and quantitatively compare and select matrix materials based on the closeness of the synthetic gradation of the constituent materials to the target gradation.

[0031] S2. Raw material preparation: The raw material storage warehouse needs to be divided into areas and stacked reasonably. Moisture-proof bags should be placed in the corners of the warehouse to prevent the materials from getting damp and deteriorating.

[0032] S3. Raw material loading: During the raw material loading process, one vehicle is required to assist in the loading and unloading process using a gantry crane equipped at the loading port.

[0033] S4. Raw material metering: All raw materials are conveyed to the metering scales via screw conveyors. Five scales are set up to classify and meter each material, namely scale No. 1, scale No. 2, transition bin scale, vibrating screen scale, and manual scale. After the materials are metered by scale No. 1, a second lifting operation is performed, in which the metered materials are conveyed to elevator No. 3 via screw conveyors, so that the materials are transferred from scale No. 1 to transition bin scale for use.

[0034] S5. Raw material input: Steel fiber is simultaneously added and mixed using a process.

[0035] S6. Variable frequency mixing: Mixing is achieved by equipping a variable frequency heavy-duty mixer. The mixing is divided into three stages: low frequency 30Hz-50Hz → high frequency 50Hz → low frequency 50Hz-30Hz.

[0036] S7, Flying Knife Start-Stop: Utilizes three 3000RPM high-speed flying knives;

[0037] S8. Discharge after mixing: After mixing is complete, open the discharge hopper door to discharge the material into the premix storage tank;

[0038] S9. Finished material storage and transportation: Premixed materials shall be packaged in drums or ton bags.

[0039] Preferably, in step S1, the fiber used is copper-plated rust-proof steel fiber. The fiber length is measured using a vernier caliper, with the main fiber length being 12mm-16mm and the auxiliary short fiber length being 7mm-9mm. The equivalent diameter of the fiber is measured using a micrometer, with the equivalent diameter of the main fiber preferably being 0.20±0.02mm and the equivalent diameter of the auxiliary fiber preferably being 0.12±0.005mm. The aspect ratio of both the main fiber and the auxiliary fiber is required to be 60-70.

[0040] Preferably, in step S2, cement is stored by direct loading into tanks, ensuring that cement is delivered as needed during production; silica fume and fly ash are stored and transported in ton bags with inner moisture-proof films. Semi-density silica fume is selected for delivery, and its particle size and microstructure are tested and analyzed upon arrival. After passing the tests, it is stored in the warehouse, with each bag placed on a forklift pallet for easy transfer; all quartz sand is delivered and stored in ton bags, and its particle size is tested and analyzed upon arrival. After passing the tests, it is stored in the warehouse; steel fiber is packaged in moisture-proof paper bags, with 5 bags stacked per layer, 12 layers per pallet, and a total of 60 bags per pallet, wrapped with an outer moisture-proof film.

[0041] Preferably, in step S3, the raw material feeding tank design of the ultra-high performance concrete premixing plant is equipped with two elevators. The No. 1 elevator is responsible for the aggregate feeding, and the powder is effectively fed by controlling the opening of the elevator's inlet and outlet valves, so that different materials are fed into the tank accordingly. The No. 2 elevator is responsible for the feeding of ultrafine powders, and is responsible for the feeding of silica fume and fly ash into the tank. The feeding of steel fibers is achieved by a conveyor belt set on one side of the mixing tank.

[0042] Preferably, in step S4, the first scale is mainly responsible for measuring the three types of quartz sand and cement. To effectively control the measurement accuracy of each material and reduce losses during the secondary lifting process, the measurement sequence of the first scale is set as coarse sand → fine sand → cement → medium sand. The transition bin scale is responsible for re-measuring the various raw materials measured by the first scale after transfer to ensure complete transfer. The second scale is responsible for measuring the two types of ultrafine particle materials. This scale is directly connected to the mixing tank to ensure that the materials can be directly put into the mixing pot after measurement, so as to reduce the mass loss of the core materials after weighing and ensure a high degree of consistency between the material measurement and the mix ratio. The vibrating screen scale is responsible for the addition of steel fibers and can be precisely measured according to the mix ratio requirements, with an accuracy of ±0.1%. The manual scale is a reserved scale. Given the variability of the material mix ratio, the reserved manual scale is directly connected to the mixing tank to accurately add the core raw materials, so as to ensure a high degree of consistency between the core material measurement and the mix ratio.

[0043] Preferably, in step S5, the materials in the transition silo are first added, namely various aggregates and cement, then steel fibers are added, and finally the materials in the second silo are added, namely silica fume and fly ash.

[0044] Unlike other machinery, adding ultrafine powder last can solve the problem of steel fibers clumping due to the large amount of ultrafine powder coating during production.

[0045] Preferably, in step S6, low-frequency stirring is used during the addition of each material to improve energy efficiency; high-frequency stirring is performed after all materials have been added to ensure that the materials are mixed evenly in a short time; low-frequency stirring is resumed after stirring is completed to save energy and improve efficiency. The stirring process can be adjusted appropriately according to changes in the raw material ratio.

[0046] Preferably, in step S7, during the stirring process, the flying knife starts 10 seconds after the initial addition time of each material, and the flying knife stops operating 10 seconds before the stirring is completed, based on the stirring time.

[0047] Preferably, in step S8, the unloading time is 10s-12s. After the bin door is completely closed, the next batch of mixing is carried out to form continuous automated production.

[0048] Preferably, in step S9, when using premixed material drums for storage, the plastic drums should be covered and sealed with self-adhesive film wrapped around them twice; when using ton bags, after sealing the ton bag opening, an outer moisture-proof film bag should be placed over it to prevent the material from getting damp. The corresponding production date and expiration date should be clearly marked on the drum or ton bag packaging.

[0049] The above description only illustrates the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention, and all such changes should be included within the protection scope of the present invention.

Claims

1. A precision production method for ultra-high performance concrete premix, characterized in that, Includes the following steps: S1. Raw Material Selection and Mix Design: Analysis of particle morphology, particle size distribution, and physicochemical characteristics of UHPC matrix materials at the microscale. Based on the experimental test results of each matrix material, comparing its unique properties with existing specifications, the quality of raw materials is identified. A combination of qualitative and quantitative analysis methods is used. On the one hand, a 10,000x industrial electron microscope is used to obtain the microscopic geometric morphology of the matrix materials, qualitatively comparing and selecting matrix materials, making it easier to distinguish between good and bad quality. On the other hand, a laser particle size analyzer is used to obtain the particle size distribution of the matrix materials, and the matrix materials are quantitatively compared based on the closeness of the synthetic gradation of the constituent materials to the target gradation. S2. Raw material preparation: The raw material storage warehouse needs to be divided into areas and stacked reasonably. Moisture-proof bags should be placed in the corners of the warehouse to prevent the materials from getting damp and deteriorating. S3. Raw material loading: During the raw material loading process, one vehicle is required to assist in the loading and unloading process using a gantry crane equipped at the loading port. S4. Raw material metering: All raw materials are conveyed to the metering scales via screw conveyors. Five scales are set up to classify and meter each material, namely scale No. 1, scale No. 2, transition bin scale, vibrating screen scale, and manual scale. After the materials are metered by scale No. 1, a second lifting operation is performed, in which the metered materials are conveyed to elevator No. 3 via screw conveyors, so that the materials are transferred from scale No. 1 to transition bin scale for use. S5. Raw material input: Steel fiber is simultaneously added and mixed using a process. S6. Variable frequency mixing: Mixing is achieved by equipping a variable frequency heavy-duty mixer. The mixing is divided into three stages: low frequency 30Hz-50Hz → high frequency 50Hz → low frequency 50Hz-30Hz. S7, Flying Knife Start-Stop: Utilizes three 3000RPM high-speed flying knives; S8. Discharge after mixing: After mixing is complete, open the discharge hopper door to discharge the material into the premix storage tank; S9. Finished material storage and transportation: Premixed material shall be packaged in drums or ton bags. In step S4, the first scale is mainly responsible for measuring the three types of quartz sand and cement. To effectively control the measurement accuracy of each material and reduce losses during the secondary lifting process, the measurement sequence of the first scale is set as coarse sand → fine sand → cement → medium sand. The transition bin scale is responsible for re-measuring the various raw materials measured by the first scale after transfer to ensure complete transfer. The second scale is responsible for measuring the two types of ultrafine particle materials. This scale is directly connected to the mixing tank to ensure that the materials can be directly put into the mixing pot after measurement, so as to reduce the mass loss of the core materials after weighing and ensure a high degree of consistency between the material measurement and the mix ratio. The vibrating screen scale is responsible for the addition of steel fibers and can be precisely measured according to the mix ratio requirements, with an accuracy of ±0.1%. The manual scale is a reserved scale. Given the variability of the material mix ratio, the reserved manual scale is directly connected to the mixing tank to accurately add the core raw materials, so as to ensure a high degree of consistency between the core material measurement and the mix ratio. In step S5, the materials in the transition silo are first added, namely various aggregates and cement, then steel fibers are added, and finally the materials in the second silo are added, namely silica fume and fly ash.

2. The precision production method for ultra-high performance concrete premix according to claim 1, characterized in that: In step S1, the fiber used is copper-plated rust-proof steel fiber. The fiber length is measured using a vernier caliper. The main fiber length is 12mm-16mm, and the auxiliary short fiber length is 7mm-9mm. The equivalent diameter of the fiber is measured using a micrometer. The equivalent diameter of the main fiber should be 0.20±0.02mm, and the equivalent diameter of the auxiliary fiber should be 0.12±0.005mm. The aspect ratio of both the main fiber and the auxiliary fiber is required to be 60-70.

3. The precision production method for ultra-high performance concrete premix according to claim 1, characterized in that: In step S2, cement is stored by direct loading into tanks, ensuring that cement is delivered as needed during production. Silica fume and fly ash are stored and transported in ton bags with an inner moisture-proof film. Semi-density silica fume is selected for delivery, and its particle size and microstructure are tested and analyzed upon arrival. After passing the tests, the bags are stored in the warehouse, with forklift pallets placed at the bottom for easy transport. All quartz sand is delivered and stored in ton bags. Upon arrival, its particle size is tested and analyzed, and after passing the tests, it is stored in the warehouse. Steel fiber is packaged in moisture-proof paper bags, with 5 bags stacked per layer, 12 layers per pallet, and a total of 60 bags per pallet, all wrapped with a moisture-proof film.

4. The precision production method for ultra-high performance concrete premix according to claim 1, characterized in that: In step S3, the ultra-high performance concrete premixing plant is designed with two elevators for feeding raw materials into the tank. The first elevator is responsible for lifting aggregates and effectively feeding powder by controlling the opening of the elevator's inlet and outlet valves, so that different materials are fed into the tank accordingly. The second elevator is responsible for feeding ultrafine powders, including silica fume and fly ash. The feeding of steel fibers is achieved through a conveyor belt set on one side of the mixing tank.

5. The precision production method for ultra-high performance concrete premix according to claim 1, characterized in that: In step S6, low-frequency stirring is used during the material addition process to improve energy efficiency; after all materials are added, high-frequency stirring is performed to ensure that the materials are mixed evenly in a short time; after stirring is completed, low-frequency stirring is resumed to save energy and improve efficiency.

6. The precision production method for ultra-high performance concrete premix according to claim 1, characterized in that: In step S7, during the stirring process, the flying knife starts 10 seconds after the initial addition time of each material. The cutting time of the flying knife is calculated based on the stirring time, and the flying knife stops operating 10 seconds before the stirring is completed.

7. The precision production method for ultra-high performance concrete premix according to claim 1, characterized in that: In step S8, the unloading time is 10s-12s. After the silo door is completely closed, the next batch of mixing begins, forming continuous automated production.

8. The precision production method for ultra-high performance concrete premix according to claim 1, characterized in that: In step S9, when using a premixed material container, the plastic container of the premixed material is covered with a lid and sealed with two layers of self-adhesive film; when using a ton bag packaging method, after the ton bag opening is sealed, an outer film moisture-proof bag is placed over it to prevent the material from getting damp.

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