Coarse aggregate ultra-high performance concrete feeding and stirring device and control method

Abstract

The invention provides a coarse aggregate ultra-high performance concrete feeding and stirring device and a control method, and belongs to the technical field of concrete manufacturing, the coarse aggregate ultra-high performance concrete feeding and stirring device comprises working steps of a control unit, a premix feeding system, a steel fiber feeding system, a stirring system and the stirring device, and three indexes including the stirring temperature, the stirring time and the stirring speed are monitored; the cement hydration reaction can be stably carried out, the concrete strength is stably improved, cement particles and coarse aggregate are tightly combined to form a compact bone glue structure, so that the erosion resistance of the concrete is improved, concrete composition materials such as the coarse aggregate, the cement and water are fully mixed and dispersed in a stirrer, the strength of the concrete is improved, and the service life of the concrete is prolonged. The performance and the quality of the coarse aggregate concrete are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of concrete manufacturing, and in particular to a coarse aggregate ultra-high performance concrete feeding and mixing device and a control method. Background Art

[0002] Bridge deck, also known as driving lane slab, is the upper load-bearing structure of the bridge. It is required to be able to bear large loads and have good durability and corrosion resistance. Bridge deck is generally made of reinforced concrete. However, in the construction of some bridges with large spans and large loads, ordinary concrete is not enough to meet its requirements. Therefore, ultra-high performance concrete UHPC with higher strength, durability and corrosion resistance is required. Since ultra-high performance concrete UHPC is added with fibers and other materials, its mixing difficulty is relatively high, and it is difficult to achieve a uniform mixing effect using ordinary concrete mixing devices. Summary of the invention

[0003] The purpose of the present invention is to provide a coarse aggregate ultra-high performance concrete feeding and mixing device and a control method to solve the problem that the ultra-high performance concrete UHPC of the prior art proposed in the above background technology has relatively high mixing difficulty and it is difficult to achieve a uniform mixing effect using an ordinary concrete mixing device.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A coarse aggregate ultra-high performance concrete feeding and mixing device, including a control unit, a premix feeding system, a steel fiber feeding system, and a mixing system;

[0006] The control unit is used for automatic control of the concrete feeding and mixing device;

[0007] The premix delivery system is used to transport the premix to the mixing system;

[0008] A steel fiber delivery system, used for delivering steel fibers into the mixing system during the mixing process;

[0009] The stirring system includes multiple mixers, each of which is equipped with multiple motors and a stirring bin. Each stirring bin is provided with stirring shafts corresponding to the number of motors. The motor is connected to the stirring shaft via a transmission device. A stirring arm is provided on the stirring shaft. The stirring shaft drives the stirring arm to rotate under the drive of the motor to stir the materials. The mixer is also provided with multiple feeding channels.

[0010] The mixing system further comprises a liquid dispenser provided on one side of the mixer, and the liquid dispenser is used for dispensing the liquid required in the concrete.

[0011] Furthermore, the premix delivery system includes a crane and a premix bag, and the crane can move the premix bag above the plurality of mixers and deliver the premix bag to the delivery channel.

[0012] Furthermore, the steel fiber delivery system comprises a steel fiber storage cylinder and a first lower hopper, wherein the first lower hopper is arranged on the mixer, and each of the first lower hoppers corresponds to a feeding channel of the multiple mixers below.

[0013] Furthermore, the control unit is arranged on one side of the mixer.

[0014] Furthermore, the mixer is arranged on a supporting frame, and a mixture outlet is provided at the bottom of the mixer.

[0015] Furthermore, a rotation speed sensor and a timer are arranged on the stirring shaft of the stirrer, and a temperature sensor is arranged on the stirring arm. The rotation speed sensor, the timer and the temperature sensor are electrically connected to the control unit.

[0016] As a preferred technical solution of the present invention, a control method for a coarse aggregate ultra-high performance concrete feeding and mixing device comprises the following steps:

[0017] S1. Place the premix bag: The crane places the premix bag into the feeding channel of the mixer;

[0018] S2, dry material mixing: the mixer receives the mixing signal and mixes the premix for the first time;

[0019] S3, adding liquid: the liquid dispenser adds liquid into the mixer;

[0020] S4, first wet material mixing: liquid and premix are mixed into premixed mortar;

[0021] S5. Putting in steel fiber: the steel fiber storage cylinder receives the putting signal and puts the steel fiber into the corresponding mixer;

[0022] S6. Second wet material stirring: The mixer receives the stirring signal and performs the second stirring until the stirring is completed.

[0023] Furthermore, the control unit monitors the stirring temperature and stirring speed in steps S2 to S6 through a rotation speed sensor and a temperature sensor, wherein the stirring temperature is 12° C. to 50° C. and the stirring speed is 24.5 r / min to 32.6 r / min.

[0024] Furthermore, the control unit monitors the stirring time by means of a timer, including:

[0025] In step S2, the dry material stirring time is 3 to 4 minutes;

[0026] In step S4, the first wet material stirring time is 3 minutes;

[0027] In step S5, 1min≤steel fiber feeding time<2min;

[0028] In step S6, the second wet material stirring time is 3 to 4 minutes;

[0029] From steps S4 to S6, i.e., from the first stirring of the wet materials to the completion of stirring, the time is ≤ 8 minutes.

[0030] In summary, the beneficial effects of the present invention are:

[0031] In steps S4 to S6 of the stirring device control method, three indicators, namely, stirring temperature, stirring time and stirring speed, are monitored. The stirring temperature affects the speed of cement hydration reaction of coarse aggregate concrete. The higher the stirring temperature, the faster the cement hydration reaction speed. When the temperature is reduced to below 12°C, the cement hydration reaction speed will be slowed down. The cement hydration reaction is slow, and the strength growth of the concrete will also be affected, resulting in low strength and easy cracking. Therefore, increasing the stirring temperature can increase the cement hydration reaction speed, but when the stirring temperature exceeds 50°C, the concrete may cause premature coagulation and cracking, thereby affecting its final performance. At the same time, during the hardening of the concrete, the cement releases a large amount of hydration heat, resulting in a continuous increase in the internal temperature. At this time, if the stirring temperature exceeds 50°C, the internal temperature rises too fast, which may generate large temperature stresses on the surface and inside of the concrete. When these temperature stresses exceed the crack resistance of the concrete, cracks will be generated. Therefore, selecting a stirring temperature of 12°C to 50°C can make the cement hydration reaction proceed smoothly, the concrete strength grows steadily, and no large temperature stresses will be generated on the surface and inside of the concrete, thereby ensuring the performance and quality of the coarse aggregate concrete.

[0032] The mixing speed refers to the rotation speed of the mixer's mixing shaft, which directly affects the uniformity, stability and strength of concrete. When the mixing speed is too high, although the concrete components can be mixed faster, air will be drawn into the concrete to form larger pores, resulting in a decrease in concrete strength. When the mixing speed is too low, the cement particles and coarse aggregate will not be tightly combined. Therefore, monitoring the mixing speed and keeping it within the design range can ensure that the cement particles and coarse aggregate are tightly combined to form a dense cement structure, thereby improving the concrete's anti-erosion performance.

[0033] Mixing time refers to the time required from feeding to mixing completion. When the mixing time is too short, the cement particles fail to fully contact with water and undergo hydration reaction, resulting in insufficient production of hydration products, which in turn affects the strength of the concrete. At the same time, the materials fail to be fully mixed and dispersed, resulting in uneven distribution of materials inside the concrete, making its various parts uneven in strength and reducing the overall performance. When the mixing time is too long, the surface of the coarse aggregate in the concrete will be excessively worn, the roughness of the coarse aggregate surface will be reduced, and the mechanical bite between the coarse aggregate and the cement slurry will be reduced, thereby affecting the overall strength of the concrete. Therefore, monitor the mixing time to keep it within the design range to ensure that the coarse aggregate, cement, water and other concrete components are fully mixed and dispersed in the mixer to improve the strength of the concrete.

[0034] Monitoring the distribution of steel fibers in concrete can affect the distribution of aggregates. Monitoring the total mixing time and the mixing time after the steel fibers are added can make the steel fibers more evenly distributed in the coarse aggregate, thereby avoiding the problem of excessive or low strength in local areas of concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic elevation diagram of the overall structure of the present invention;

[0036] Figure 2 It is a plan view of the overall structure of the present invention;

[0037] Figure 3 is a flow chart of a control method of a stirring device of the present invention;

[0038] Among them: 100-premix delivery system, 110-crane, 200-steel fiber delivery system, 210-steel fiber storage cylinder, 220-first lower hopper, 300-mixing system, 310-mixer, 311-feeding channel, 312-mixture outlet, 320-liquid dispenser, 330-support frame. DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments given here are only used to illustrate and explain the present invention, and cannot be used to limit the present invention.

[0040] It should be noted that many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention may also have other implementations and variations thereof. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0041] like Figure 1-2As shown, the coarse aggregate ultra-high performance concrete feeding and mixing device includes a control unit (not shown), a premix feeding system 100, a steel fiber feeding system 200, and a mixing system 300;

[0042] The control unit is used for automatic control of the concrete feeding and mixing device;

[0043] The premix delivery system 100 is used to transport the premix to the mixing system 300;

[0044] A steel fiber delivery system 200, used to deliver steel fibers to the stirring system 300 during the stirring process;

[0045] The stirring system 300 includes a plurality of stirrers 310, each of which is equipped with a plurality of motors and a stirring bin. Each stirring bin is provided with stirring shafts corresponding to the number of motors. The motor is connected to the stirring shaft via a transmission device. A stirring arm is provided on the stirring shaft. The stirring shaft drives the stirring arm to rotate under the drive of the motor to stir the materials. The stirrer 310 is also provided with a plurality of feeding channels 311.

[0046] The stirring shaft is a single-track shaft mixer 310. The single-track shaft design can ensure that the materials are fully mixed and evenly distributed during the stirring process, improve the stirring efficiency, and the structure is stable and reliable, and can operate stably for a long time.

[0047] The stirring arm adopts a spiral stirring arm, which forms material flow when rotating to promote mixing between materials.

[0048] The mixing system 300 further includes a liquid dispenser 320 disposed on one side of the mixer 310. The liquid dispenser 320 is used to dispense liquid required in the concrete. The liquid is water. The liquid is mixed with the premix to form a premixed mortar.

[0049] like Figure 1 As shown, the premix delivery system 100 includes a crane 110 and a premix bag (not shown in the figure). The crane 110 can move the premix bag above the multiple mixers 310 and deliver the premix bag to the delivery channel 311.

[0050] like Figure 2 As shown, the steel fiber delivery system 200 includes a steel fiber storage cylinder 210 and a first lower hopper 220. The first lower hopper 220 is arranged on the mixer 310, and each of the first lower hoppers 220 corresponds to a feeding channel 311 of the multiple mixers 310 below.

[0051] In actual production, the control unit is arranged on one side of the mixer 310 .

[0052] like Figure 1 As shown, the mixer 310 is disposed on a support frame 330 , and a mixture outlet 312 is disposed at the bottom thereof.

[0053] In actual production, a speed sensor (not shown in the figure) and a timer (not shown in the figure) are set on the stirring shaft of the mixer 310, and a temperature sensor (not shown in the figure) is set on the stirring arm. The speed sensor, timer and temperature sensor are electrically connected to the control unit.

[0054] In actual production, the control method of the coarse aggregate ultra-high performance concrete feeding and mixing device includes the following steps:

[0055] S1. Adding a premix bag: The crane 110 adds the premix bag to the feeding channel 311 of the mixer 310;

[0056] S2, dry material stirring: the mixer 310 receives a stirring signal and stirs the premix for the first time;

[0057] S3, adding liquid: the liquid dispenser 320 adds liquid to the mixer 310;

[0058] S4, first wet material mixing: liquid and premix are mixed into premixed mortar;

[0059] S5, placing steel fibers: the steel fiber storage cylinder 210 receives a placing signal and places the steel fibers into the corresponding mixer 310;

[0060] S6. Second wet material stirring: the mixer 310 receives the stirring signal and performs the second stirring until the stirring is completed.

[0061] In actual production, the control unit monitors the stirring temperature and stirring speed in steps S2 to S6 through a speed sensor and a temperature sensor, wherein the stirring temperature is 12° C. to 50° C. and the stirring speed is 24.5 r / min to 32.6 r / min.

[0062] In actual production, the control unit monitors the mixing time through a timer, including:

[0063] In step S2, the dry material stirring time is 3 to 4 minutes;

[0064] In step S4, the first wet material stirring time is 3 minutes;

[0065] In step S5, 1min≤steel fiber feeding time<2min;

[0066] In step S6, the second wet material stirring time is 3 to 4 minutes;

[0067] From steps S4 to S6, i.e., from the first stirring of the wet materials to the completion of stirring, the time is ≤ 8 minutes.

[0068] The cement hydration reaction in concrete is the main chemical reaction in the mixing process. The mixing temperature will affect its reaction speed. The higher the mixing temperature, the faster the cement hydration reaction speed. When the temperature drops below 12℃, the cement hydration reaction speed will be slowed down. The cement hydration reaction is slow, and the strength growth of concrete will also be affected, resulting in low strength and easy cracks. Therefore, increasing the mixing temperature can increase the cement hydration reaction speed, but when the mixing temperature exceeds 50℃, it may cause the concrete to coagulate and crack prematurely, thereby affecting its final performance. At the same time, during the hardening of concrete, cement releases a large amount of hydration heat, causing the internal temperature to continue to rise. At this time, if the mixing temperature exceeds 50℃, the internal temperature rises too fast, which may cause large temperature stresses on the surface and inside of the concrete. When these temperature stresses exceed the crack resistance of the concrete, cracks will occur. Therefore, choosing a mixing temperature of 12℃~50℃ can make the cement hydration reaction proceed smoothly, the concrete strength grows steadily, and no large temperature stress will be generated on the surface and inside of the concrete, ensuring the performance and quality of coarse aggregate concrete.

[0069] If the temperature does not reach the design value, temperature adjustment is required. For example, when mixing concrete in winter, in order to meet the minimum mold entry temperature requirement of 12°C, it is preferred to use heating water to adjust the mixture temperature, but the heating temperature of the water must not be higher than 80°C.

[0070] Mixing time refers to the time required from adding materials to completing mixing. When the mixing time is too short, insufficient hydration products will be generated, affecting the strength of the concrete. When the mixing time is too long, the surface of the coarse aggregate in the concrete will be excessively worn, reducing the mechanical bite between the coarse aggregate and the cement slurry, and reducing the overall performance. The dry material mixing time is 3 to 4 minutes, so that the premix is ​​fully mixed before adding the liquid, and the coarse aggregate and cement additives are more evenly distributed. After adding the liquid, the first wet material mixing time is guaranteed to be 3 minutes to ensure that the coarse aggregate, cement, water and other concrete components are fully mixed and dispersed in the mixer.

[0071] In coarse aggregate ultra-high performance concrete, steel fibers can improve the tensile, bending and shear strength, increase the toughness and ductility of concrete, and increase its impact resistance, fatigue resistance and wear resistance. They can effectively prevent the expansion of existing defects in concrete and delay the appearance of new cracks. At the same time, they can improve the compactness of the cement matrix and prevent the intrusion of external moisture, thereby enhancing the overall stability and safety of the structure. The distribution of steel fibers in concrete can affect the distribution of aggregates. By monitoring the mixing time after the steel fibers are added, the steel fibers can be more evenly distributed in the coarse aggregate, thereby avoiding the problem of excessive or low strength in local areas of concrete.

[0072] The mixing speed refers to the rotation speed of the mixer's mixing shaft, which directly affects the uniformity, stability and strength of concrete. The mixing speed should be monitored and maintained at 24.5r / min~32.6r / min to allow the cement particles and coarse aggregate to combine tightly to form a dense cement structure, thereby improving the concrete's anti-erosion performance.

[0073] It should be understood that the above-mentioned embodiments are one or more embodiments of the present invention, and there are many other embodiments and variations thereof based on the present invention; the variations and modifications made by ordinary technicians in this industry through the present invention without making pioneering innovations all fall within the scope of protection of the present invention.

Claims

1. Coarse aggregate ultra-high performance concrete feeding and mixing device, characterized by: It includes control unit, premix delivery system, steel fiber delivery system and stirring system; The control unit is used for automatic control of the concrete feeding and mixing device; The premix delivery system is used to transport the premix to the mixing system; A steel fiber delivery system, used for delivering steel fibers into the mixing system during the mixing process; The stirring system includes multiple mixers, each of which is equipped with multiple motors and a stirring bin. Each stirring bin is provided with stirring shafts corresponding to the number of motors. The motor is connected to the stirring shaft via a transmission device. A stirring arm is provided on the stirring shaft. The stirring shaft drives the stirring arm to rotate under the drive of the motor to stir the materials. The mixer is also provided with multiple feeding channels. The mixing system further comprises a liquid dispenser provided on one side of the mixer, and the liquid dispenser is used for dispensing the liquid required in the concrete.

2. The coarse aggregate ultra-high performance concrete feeding and mixing device according to claim 1, characterized in that: The premix delivery system comprises a crane and a premix bag. The crane can move the premix bag above the plurality of mixers and deliver the premix bag to the delivery channel.

3. The coarse aggregate ultra-high performance concrete feeding and mixing device according to claim 2, characterized in that: The steel fiber delivery system comprises a steel fiber storage cylinder and a first lower hopper, wherein the first lower hopper is arranged on the mixer, and each of the first lower hoppers corresponds to a feeding channel of the multiple mixers below.

4. The coarse aggregate ultra-high performance concrete feeding and mixing device according to claim 1, characterized in that: The control unit is arranged at one side of the mixer.

5. The coarse aggregate ultra-high performance concrete feeding and mixing device according to claim 1, characterized in that: The mixer is arranged on a supporting frame, and a mixture outlet is arranged at the bottom of the mixer.

6. The coarse aggregate ultra-high performance concrete feeding and mixing device according to claim 1, characterized in that: A rotation speed sensor and a timer are arranged on the stirring shaft of the stirrer, and a temperature sensor is arranged on the stirring arm. The rotation speed sensor, the timer and the temperature sensor are electrically connected to the control unit.

7. The control method of any one of the coarse aggregate ultra-high performance concrete feeding and mixing devices according to claims 1-6, characterized in that: The following steps are involved: S1. Place the premix bag: The crane places the premix bag into the feeding channel of the mixer; S2, dry material mixing: the mixer receives the mixing signal and mixes the premix for the first time; S3, adding liquid: the liquid dispenser adds liquid into the mixer; S4, first wet material mixing: liquid and premix are mixed into premixed mortar; S5. Putting in steel fiber: the steel fiber storage cylinder receives the putting signal and puts the steel fiber into the corresponding mixer; S6. Second wet material stirring: The mixer receives the stirring signal and performs the second stirring until the stirring is completed.

8. The control method for the coarse aggregate ultra-high performance concrete feeding and mixing device according to claim 7, characterized in that: The control unit monitors the stirring temperature and stirring speed in steps S2 to S6 through a rotation speed sensor and a temperature sensor, wherein the stirring temperature is 12° C. to 50° C. and the stirring speed is 24.5 r / min to 32.6 r / min.

9. The control method of the coarse aggregate ultra-high performance concrete feeding and mixing device according to claim 7, characterized in that: The control unit monitors the stirring time through a timer including: In step S2, the dry material stirring time is 3 to 4 minutes; In step S4, the first wet material stirring time is 3 minutes; In step S5, 1min≤steel fiber feeding time<2min; In step S6, the second wet material stirring time is 3 to 4 minutes; From steps S4 to S6, i.e., from the first stirring of the wet materials to the completion of stirring, the time is ≤ 8 minutes.

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