Ultra-high performance concrete premix production equipment based on fine gradation control and quality control method

Abstract

The application provides an ultra-high performance concrete premix production equipment and a quality control method based on fine gradation control, belongs to the technical field of concrete manufacturing, and adopts a control unit to control mutual cooperation between a feeding system, a metering system and a batching system, so that the above system can automatically complete various control operations, such as automatic washing, drying, screening, metering, feeding and mixing, and the like. The highly automated production mode avoids errors and instability that may be caused by manual operation, and specifically requires quality control of the production process, such as the clay content and water content of the aggregate, the gradation qualification rate, the metering precision of the aggregate, the powder and the additive, and the like, so as to ensure the production quality of the ultra-high performance concrete premix.

Description

Technical Field

[0001] This invention relates to the field of concrete manufacturing technology, and more specifically, to ultra-high performance concrete premix production equipment and quality control methods based on refined gradation control. Background Technology

[0002] Bridge decks are a crucial component of bridge structures, directly bearing loads from vehicles and pedestrians and transferring these loads to the main bridge structure. They require both the ability to withstand significant loads and excellent durability and corrosion resistance. While reinforced concrete is commonly used for bridge decks, ordinary concrete is insufficient for some large-span, high-load bridges. Therefore, ultra-high performance concrete (UHPC), with its superior strength, durability, and corrosion resistance, is needed. However, current UHPC production processes suffer from several drawbacks. High mud content in aggregates increases water demand, reduces workability and strength, and increases shrinkage, leading to cracking. High water content also causes hydration reactions between free water and cementitious materials in the premix, affecting premix quality. Furthermore, low material sieving and grading rates result in uneven aggregate particle distribution, a lack of intermediate-sized particles, and high porosity. Additionally, low precision in the metering and batching system prevents the achievement of designed mix proportions, further impacting the concrete's strength, durability, and stability. Summary of the Invention

[0003] The purpose of this invention is to provide a production equipment for ultra-high performance concrete premix based on refined gradation control, so as to solve the problems mentioned in the background art of high mud and water content in aggregates, low material screening and grading pass rate, and low accuracy of metering and batching system in the production of existing technologies.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] Ultra-high performance concrete premix production equipment based on refined gradation control includes a control unit, a feeding system, a metering system, and a batching system;

[0006] The control unit is used for the automated control of premixed concrete production.

[0007] The feeding system includes a feeding belt and a material bag, and the feeding system is used to transport materials;

[0008] The metering system includes a powder metering mechanism and an aggregate metering mechanism, which are used to meter powder and aggregate respectively;

[0009] The batching system includes a powder batching mechanism and an aggregate batching mechanism, used for batching powder and aggregate respectively. The powder batching mechanism includes multiple silos, with a powder conveyor belt below each silo. The powder conveyor belt transports various powders to the powder metering mechanism. Below the powder metering mechanism is a powder mixing cylinder, and below the powder mixing cylinder is the aggregate bag. The aggregate batching mechanism includes a washing machine, a dryer, and a screening machine. The aggregate is washed, dried, and screened by the washing machine, dryer, and screening machine before being fed into the aggregate metering mechanism. Below the aggregate metering mechanism is an aggregate mixing cylinder, and below the aggregate mixing cylinder is an aggregate conveyor belt. The aggregate conveyor belt extends to the location of the aggregate bag to transport the aggregate to the aggregate bag.

[0010] Furthermore, the conveyor belts of the feeding system include a powder conveyor belt between the hopper and the powder metering mechanism; an aggregate conveyor belt between the aggregate mixing cylinder and the material bag; three screening belts below the screening machine; a washing and drying belt for feeding the dryer; and the material bag is connected to the powder batching mechanism and the aggregate batching mechanism respectively, for receiving the premixed material from the batching system and transporting it to the concrete mixing device.

[0011] Furthermore, the silos store different powders, including cement, silica fume, and microspheres; each silo is equipped with a feeding hopper, which is used to control the feeding speed of the materials.

[0012] Furthermore, the washing machine is a wheel-type sand washing machine, which includes a washing tank and an impeller. The impeller drives the raw material of the aggregate to be stirred, turned over and washed in the washing tank to meet the design requirements.

[0013] Furthermore, the screening machine is a probability screen, which has multiple screen surfaces and can screen aggregates according to their probability distribution.

[0014] Furthermore, the powder and aggregate metering mechanism includes a metering hopper, which has a built-in precision weighing scale that can perform automatic metering and automatic weighing control.

[0015] Furthermore, the batching system also includes an additive dispenser, which is located between the aggregate batching mechanism and the powder batching mechanism. Its dispensing port is used to dispense the additive onto the aggregate conveyor belt and transport it together with the aggregate to the material bag.

[0016] As a preferred technical solution of the present invention, the quality control method for ultra-high performance concrete premix production equipment based on refined gradation control is characterized by comprising the following steps:

[0017] S100. Raw material cleaning and drying of aggregates: The raw materials of the aggregates are cleaned by a wheel bucket sand washing machine and then dried by a dryer. During the cleaning and drying process, the mud content and water content of the aggregates are controlled to be <0.5% and <0.5% respectively.

[0018] S200, aggregate screening

[0019] The first step is the initial screening. The probability screen is started to make the screening equipment vibrate. The aggregate is fed evenly into the screen frame through the feeding device. According to the designed material mix ratio, the aggregates of different particle sizes are separated into their respective screen layers, and the screening results are recorded.

[0020] The second step is secondary screening: Based on the screening results of the previous step, the compounding ratio is adjusted, and the probability screen is restarted for secondary screening. The gradation qualification rate of the aggregate is controlled by the secondary compounding screening of the probability screen, wherein the gradation qualification rate of the secondary screening is 100%.

[0021] S300, Metering of aggregates and powders: According to the preset ratio, the aggregates, powders, and additives are fed into each metering hopper through the feeding system. The precise weighing scale in the metering hopper monitors the weight of the aggregates, powders, and additives in real time through multiple sensors. The metering accuracy of the aggregates is 1%, the metering accuracy of the powders is 0.5%, and the metering accuracy of the additives is <5g. After metering is completed, the control unit will send a signal until the preset ratio requirement is reached and the feeding stops. Then the material enters the corresponding mixing cylinder.

[0022] S400, Concrete premix material mixing: The additives and the aggregates mixed from the aggregate mixing cylinder are transported to the material bag via the aggregate conveyor belt, and the powders batched from the powder mixing cylinder are transported to the material bag via the powder conveyor belt. The aggregates, the powders, and the additives are added to the material bag according to the designed material mixing ratio.

[0023] In summary, the beneficial effects of this invention are:

[0024] This invention is based on a high-performance premixed concrete production equipment with refined gradation control. It adopts a control unit to control the feeding system, metering system and batching system to cooperate with each other, so that the above systems can automatically complete various control operations, such as automatic washing and drying, screening, metering, feeding and mixing. This highly automated production method avoids the errors and instabilities that may be caused by manual operation.

[0025] Simultaneously, various suitable equipment are used to produce premixed materials. In the raw material cleaning and drying of aggregates, a wheel-type sand washer and a three-pass dryer are used. The wheel-type sand washer, through the transmission of an electric motor and a reducer, drives the impeller in the cleaning tank to rotate continuously in the cleaning tank, stirring, turning, and washing the raw materials of aggregates in the water, and then dewatering the raw materials of the aggregates in the impeller before they are discharged. The three-pass dryer consists of an inner cylinder, a middle cylinder, and an outer cylinder, forming a self-insulating circulating structure with strong overload resistance, large processing capacity, low fuel consumption, and low drying cost. The cleaned aggregates first enter the inner cylinder, and then pass through the middle cylinder and the outer cylinder in sequence, tumbling in the drum and fully contacting the hot air. The moisture gradually evaporates and is discharged, realizing co-current and counter-current drying.

[0026] The screening system employs a multi-point driven probability screen, which uses probability screening theory to guide the initial screening of aggregates. Then, a secondary screening is performed based on the results of the initial screening to achieve more precise gradation control.

[0027] Furthermore, specific requirements are put forward for the quality control of the production process. In step S100, ensuring that the mud content of the aggregate is <0.5% helps to reduce the water demand in the concrete mixture, thereby improving the workability and strength of the concrete; it can also reduce the unclosed pores in the concrete, improving its impermeability and freeze-thaw resistance; ensuring that the water content is <0.5% reduces the free water in the aggregate, extends the shelf life of the premix, and makes the metering and batching of various materials in the concrete more accurate.

[0028] In step S400, the screening efficiency is effectively improved by compound screening, the non-uniformity of aggregates is reduced, the gradation qualification rate of the finished product is controlled, the aggregate gradation of concrete is optimized, the porosity is reduced, thereby improving the compressive strength and durability of concrete.

[0029] In step S300, the aggregate metering accuracy is 1%, the powder metering accuracy is 0.5%, and the additive metering accuracy is within 5g. High-precision metering can ensure the uniformity and consistency of concrete and reduce the fluctuation of concrete performance caused by metering errors.

[0030] Using a suitable mixing ratio in step S400 can improve the slump and spread of concrete, making it easier to construct and pour, while reducing segregation; it can also improve the impermeability and durability of concrete; reduce the porosity inside the concrete, improve its impermeability, and extend the service life of the structure; and finally improve the crack resistance of concrete, reduce the generation and propagation of cracks, and improve the overall stability of the structure. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall elevation of the present invention;

[0032] Figure 2 This is a schematic diagram of the cleaning machine structure of the present invention;

[0033] Among them: 100-feeding system, 110-belt, 111-powder belt, 112-aggregate belt, 113-screening belt, 114-washing and drying belt, 120-material bag, 200-metering system, 210-powder metering mechanism, 220-aggregate metering mechanism, 300-batching system, 310-powder batching mechanism, 311-silo, 312-feeding hopper, 313-powder mixing cylinder, 320-aggregate batching mechanism, 321-washing machine, 322-dryer, 323-screening machine, 324-aggregate mixing cylinder, 330-additive dispenser. Detailed Implementation

[0034] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments given herein are for illustration and explanation only and are not intended to limit the present invention.

[0035] It should be noted that many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may have other embodiments and variations thereof. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0036] like Figure 1-2 As shown, this is a production equipment for ultra-high performance concrete premixes based on refined gradation control.

[0037] Includes a control unit (not shown in the figure), a feeding system 100, a metering system 200, and a batching system 300;

[0038] The control unit is used for the automated control of premixed concrete production.

[0039] The feeding system 100 includes a feeding belt and a material bag 120, and the feeding system 100 is used to transport materials;

[0040] The metering system 200 includes a powder metering mechanism 210 and an aggregate metering mechanism 220, which are used to meter powder and aggregate respectively.

[0041] The batching system 300 includes a powder batching mechanism 310 and an aggregate batching mechanism 320, respectively used for batching powder and aggregate. The powder batching mechanism 310 includes multiple hoppers 311, with a powder conveyor belt 111 below each hopper 311. The powder conveyor belt 111 transports various powders to the powder metering mechanism 210. A powder mixing cylinder 313 is located below the powder metering mechanism 210, and the material bag 120 is located below the powder mixing cylinder 313. The aggregate batching system 320... The material handling mechanism 320 includes a washing machine 321, a dryer 322, and a screening machine 323. The aggregates are washed, dried, and screened by the washing machine 321, the dryer 322, and the screening machine 323, respectively, and then fed into the aggregate metering mechanism 220. An aggregate mixing cylinder 324 is provided below the aggregate metering mechanism 220, and an aggregate conveyor belt 112 is provided below the aggregate mixing cylinder 324. The aggregate conveyor belt 112 extends to the position of the material bag 120 and is used to transport the aggregates to the material bag 120.

[0042] like Figure 1 As shown, the conveyor belt 110 of the feeding system 100 includes a powder conveyor belt 111 disposed between the hopper 311 and the powder metering mechanism 210; an aggregate conveyor belt 112 disposed between the aggregate mixing cylinder 324 and the material bag 120; three screening belts 113 disposed below the screening machine 323; a washing and drying belt 114 for feeding the dryer 322; and the material bag 120 is connected to the powder batching mechanism 310 and the aggregate batching mechanism 320 respectively, for receiving the premixed material prepared from the batching system 300 and transporting it to the concrete mixing device (not shown in the figure).

[0043] like Figure 1 As shown, the silos 311 store different powders, and the powder packages 120 include cement, silica fume, and microspheres; each silo 311 is provided with a feeding hopper 312, which is used to control the feeding speed of the materials.

[0044] like Figure 2 As shown, the washing machine 321 is a wheel-type sand washing machine. Through the transmission of the motor and the reducer, the impeller in the washing tank is driven to rotate continuously in the washing tank, stirring, turning and washing the raw materials of the aggregate in the washing tank in the water, and then discharging the raw materials of the aggregate after dehydration in the impeller.

[0045] like Figure 1 As shown, the dryer 322 is a three-pass dryer 322, which consists of an inner cylinder, a middle cylinder and an outer cylinder, forming a self-insulating circulating structure. It has strong overload resistance, large processing capacity, low fuel consumption and low drying cost. The washed aggregate first enters the inner cylinder, and then passes through the middle cylinder and the outer cylinder in sequence. It tumbles in the drum and fully contacts the hot air. The moisture gradually evaporates and is discharged, realizing co-current and counter-current drying.

[0046] like Figure 1 As shown, the screening machine 323 is a probability screen. The probability screen is a multi-point driven type, which generates vibration through multiple motors or eccentric blocks to achieve efficient screening of aggregates on the screen. It has multiple screen surfaces, with the screen surface inclination angle increasing from top to bottom and the screen hole size decreasing. It can screen according to the probability distribution of aggregates and is suitable for grading and screening of various aggregates.

[0047] In actual production, the aggregate batching mechanism 320 is also equipped with dust removal equipment.

[0048] like Figure 1 As shown, the powder and aggregate metering mechanism 220 includes a metering hopper, which contains a precision weighing scale (not shown in the figure). The precision weighing scale can perform automatic metering and automatic weighing control, thereby improving production efficiency and reducing manual operation.

[0049] like Figure 1 As shown, the batching system 300 also includes an additive dispenser 330, which is located between the aggregate batching mechanism 320 and the powder batching mechanism 310. Its dispensing port is used to dispense additives onto the aggregate conveyor belt 112 and transport them together with the aggregate to the material bag 120. The additives include expansion agents, water-reducing agents, and antifreeze agents.

[0050] In actual production, the quality control method for the production of ultra-high performance concrete premixes based on refined gradation control is characterized by the following steps:

[0051] S100, Raw material cleaning and drying of aggregates

[0052] Step 1, washing: The raw material of the aggregate is fed into the washing tank of the wheel bucket sand washing machine, water is added to the washing tank, and the wheel bucket sand washing machine is started. After washing, the aggregate is carried to the discharge chute for discharge by the movement of the impeller. The mud content of the aggregate is controlled by adjusting the impeller speed and washing time of the wheel bucket sand washing machine. The mud content of the aggregate is <0.5%.

[0053] The second step is drying: The aggregate to be dried is fed into the three-pass dryer cylinder via the washing and drying belt 114. The three-pass dryer is started, and firstly, the aggregate to be dried is fed into the inner cylinder. Under the action of the fixed stirring impeller and forward-rotating blades in the inner cylinder, it is pushed to the other end of the inner cylinder, completing the first pass of drying. Subsequently, the aggregate to be dried is blocked back into the middle cylinder by the baffles inside the dryer, and under the action of the rotating blades in the middle cylinder, it is rotated back to the inlet end, completing the second pass. Finally, the aggregate to be dried enters the outer cylinder, and under the action of the forward-rotating blades in the outer cylinder, it is pushed to the outlet, completing the third pass. The degree of drying of the aggregate, i.e., the moisture content of the aggregate, can be controlled by adjusting the amount and speed of the aggregate to be dried. The moisture content of the aggregate is <0.5%.

[0054] S200, aggregate screening

[0055] The first step is the initial screening. The probability screen is started to make the screening equipment vibrate. The aggregate is fed into the screen frame evenly. According to the designed material mix ratio, the aggregates of different particle sizes are separated into their respective screen layers, and the screening results are recorded.

[0056] The second step is secondary screening: Based on the screening results of the previous step, the compounding ratio is adjusted, and the probability screen is restarted for secondary screening. The gradation qualification rate of the aggregate is controlled by the secondary compounding screening of the probability screen, wherein the gradation qualification rate of the secondary screening is 100%.

[0057] S300, Metering of aggregates and powders: According to the preset ratio, the aggregates, powders, and additives are fed into each metering hopper through the feeding system. The precise weighing scale in the metering hopper monitors the weight of the aggregates, powders, and additives in real time through multiple sensors. The metering accuracy of the aggregates is 1%, the metering accuracy of the powders is 0.5%, and the metering accuracy of the additives is <5g. After metering is completed, the control unit will send a signal until the preset ratio requirement is reached and the feeding stops. Then the material enters the corresponding mixing cylinder.

[0058] S400, Concrete premix material mixing: The additive and the aggregate mixed from the aggregate mixing cylinder 324 are transported to the material bag via the aggregate conveyor belt 112, and the powder material batched from the powder mixing cylinder 313 is transported to the material bag 120 via the powder conveyor belt 111. The aggregate, the powder material, and the additive are added into the material bag 120 according to the designed material mixing ratio.

[0059] It should be understood that the above embodiments are one or more embodiments of the present invention, and there are many other embodiments and variations based on the present invention; any variations and modifications made by those skilled in the art through the present invention without making pioneering innovations are all within the protection scope of the present invention.

Claims

1. An ultra-high performance concrete premix production device based on fine gradation control, characterized in that: The control unit, the feeding system, the metering system and the batching system are included. The control unit is used for the automatic control of the production of the concrete premix. The feeding system includes a feeding belt and a material bag, and is used for transporting materials. The metering system includes a powder metering mechanism and an aggregate metering mechanism, which are respectively used for metering the powder and the aggregate. The batching system includes a powder batching mechanism and an aggregate batching mechanism, which are respectively used for batching the powder and the aggregate. The powder batching mechanism includes a plurality of bins, and a powder belt is arranged below the bins.

2. The production equipment of the ultra-high performance concrete premix based on fine gradation control according to claim 1, characterized in that: The aggregate batching mechanism includes a cleaning machine, a dryer and a screening machine.

3. The production equipment of the ultra-high performance concrete premix based on fine gradation control according to claim 2, characterized in that: The belt of the feeding system includes a powder belt arranged between the bins and the powder metering mechanism, an aggregate belt arranged between the aggregate mixing drum and the material bag, three screening belts arranged below the screening machine, and a washing and drying belt used for feeding the dryer.

4. The production equipment of the fine gradation control based ultra-high performance concrete premix according to claim 3, characterized in that: The bins store different powders, and the powders include cement, silica fume and microbeads.

5. The production equipment of the ultra-high performance concrete premix based on fine gradation control according to claim 4, characterized in that: The cleaning machine is a wheel bucket sand washer, which includes a cleaning tank and an impeller. 6.The ultra-high performance concrete premix production device based on fine gradation control of claim 5, characterized in that: The screening machine is a probability screen, which has a plurality of screen surfaces and can screen the aggregate according to the probability distribution.

7. The quality control method of the fine gradation control-based ultra-high performance concrete premix production apparatus according to claim 6, characterized by, The powder and aggregate metering mechanisms include metering hoppers, which are internally provided with accurate metering scales. The batching system further includes an additive feeder arranged between the aggregate batching mechanism and the powder batching mechanism. The following steps are included: S100, cleaning and drying of the raw materials of the aggregate: the raw materials of the aggregate are cleaned by a wheel bucket sand washer and then dried by a dryer, wherein the content of mud in the aggregate is controlled to be less than 0.5% and the water content in the aggregate is controlled to be less than 0.5% during the cleaning and drying processes; S200, screening of the aggregate First step, initial screening: start the probability screen to make the screening equipment vibrate, the aggregate is uniformly fed into the screen frame through a feeding device, and different particle sizes of the aggregate are separated into respective screen layers according to the designed material mixing ratio, and the screening result is recorded. Second step, secondary screening: according to the screening results of the above step, adjust the compounding ratio, start the probability screen again for secondary screening, control the passing rate of the aggregate gradation through the secondary compounding and screening of the probability screen, wherein the passing rate of the secondary screening is 100%; S300, measurement of aggregate and powder: according to the preset proportion distribution, the aggregate, the powder and the additive are sent into each measuring hopper through the feeding system, the precise measurement scale in the measuring hopper monitors the weight of the aggregate, the powder and the additive in real time through various sensors, the measurement accuracy of the aggregate is 1%, the measurement accuracy of the powder is 0.5%, and the measurement accuracy of the additive is less than 5g, the control unit sends a signal after the measurement is completed, and the feeding is stopped until the preset proportion requirement is met, and then the corresponding mixing drum is entered; S400, concrete premix material mixing: the additive and the aggregate mixed from the aggregate mixing drum are transported to the material bag through the aggregate belt, the powder mixed from the powder mixing drum is transported to the material bag through the powder belt, and the above-mentioned aggregate, powder and additive are put into the material bag according to the designed material mixing ratio.

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