Apparatus for producing fresh concrete

Abstract

To provide a technique capable of promoting floc formation of cement particles in a manufacturing process of fresh concrete.SOLUTION: The fresh concrete manufacturing apparatus 1 includes a mixer body 10, a kneading blade 20, and a liquid feed unit 60. The mixer body contains a material comprising cement particles. The kneading blade 20 kneads the material in the mixer body 10. The liquid feeder 60 supplies the mixing water to the mixer body 10. The liquid feeding part 60 has a supply time adjusting mechanism for adjusting the supply time of the mixed water. Therefore, the floc formation of the cement particles can be promoted by extending the supply time of the mixing water.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for producing fresh concrete. [Background technology]

[0002] Concrete, a building material, is made from the main ingredients of fine aggregate (sand), coarse aggregate (gravel), cement, and mixing water, which are mixed together in a mixer. Fresh concrete (ready-mixed concrete) has fluidity immediately after production, but as time passes, the hydration reaction progresses and it eventually hardens.

[0003] Concrete mixes vary depending on the application, but the ratio of cement to mixing water affects the strength after hardening. In recent years, there has been an increasing demand for high-strength concrete, which is used for the columns of skyscrapers and civil engineering structures. High-strength concrete is a high-powder mix, with a relatively small amount of mixing water compared to the amount of cement.

[0004] Such a high powder content tends to reduce the fluidity of fresh concrete. However, when using fresh concrete, there are requirements for handling, such as pumping, so it is necessary to ensure that the fluidity is at least as high as required during construction.

[0005] Therefore, when producing high-strength concrete, a predetermined amount of industrial chemicals called admixtures (a type of surfactant) is added to ensure the fluidity of fresh concrete. Conventional techniques for producing high-strength concrete using admixtures are described in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2-107543 Summary of the Invention [Problem to be solved by the invention]

[0007] In the conventional method of producing fresh concrete using admixtures, fine aggregate, cement, mixing water, and admixtures are all charged into a mixer at once. Then, the fine aggregate, cement, mixing water, and admixtures are mixed in the mixer to produce mortar. After that, coarse aggregate is added to the mixer and further mixed to produce fresh concrete.

[0008] When fine aggregate, cement, mixing water, and admixtures are all added to a mixer at the same time, the admixtures are adsorbed onto the surfaces of individual cement particles in the early stages of mixing. In this case, it is difficult for cement particles to aggregate and form flocs. Furthermore, with conventional methods, most of the admixtures are consumed by adsorption onto the cement particles in the early stages of mixing. As a result, even if the required amount of admixtures is added, fresh concrete may not have the required fluidity. In such cases, it becomes necessary to increase the amount of admixture added.

[0009] Meanwhile, research by the present applicants has shown that the fluidity of fresh concrete improves when cement particles form flocs in the early stages of mixing. This is thought to be because, when cement particles form flocs, the specific surface area of ​​the cement decreases, reducing the amount of admixtures adsorbed to the cement particles in the early stages of mixing, and the excess admixture remaining in the liquid phase effectively acts on the cement particles during subsequent mixing. In this way, it is possible to improve the fluidity of fresh concrete produced by mixing (at least to achieve the desired fluidity) while saving on admixtures.

[0010] Generally speaking, the flocculation of cement particles can affect the desired properties of fresh concrete, such as its fluidity, by suppressing the amount of admixture adsorption in the early stages of mixing. Therefore, it is expected that the properties of fresh concrete can be controlled by intentionally promoting flocculation according to the mix proportion. However, no device specifically suited to promoting flocculation is known.

[0011] The present invention has been made in view of the above problems, and has an object to provide a technique capable of promoting flocculation of cement particles in the process of producing fresh concrete. [Means for solving the problem]

[0012] In order to solve the above problems, the first invention of the present application is a fresh concrete manufacturing device comprising a mixer body that contains material including cement particles, mixing blades that mix the material within the mixer body, and a liquid delivery unit that supplies a predetermined amount of mixing water to the mixer body, and the liquid delivery unit has a supply time adjustment mechanism that adjusts the supply time of the predetermined amount of mixing water.

[0013] The second invention of the present application is a fresh concrete manufacturing apparatus of the first invention, wherein the liquid supply section has a first liquid supply path that supplies mixing water using a pump and a second liquid supply path that supplies the mixing water by its own weight without using the pump, and the supply time adjustment mechanism switches between the first liquid supply path and the second liquid supply path.

[0014] A third invention of the present application is the fresh concrete manufacturing apparatus of the second invention, wherein the second liquid supply path includes a pipe having a smaller diameter than the first liquid supply path.

[0015] A fourth invention of the present application is the fresh concrete manufacturing apparatus of the second or third invention, wherein the second liquid supply path has a discharge port that locally discharges mixing water into the mixer body. [Effects of the Invention]

[0016] According to the first to fourth inventions of the present application, the supply time adjusting mechanism can be used to lengthen the supply time of mixing water, thereby promoting the formation of flocs of cement particles.

[0017] In particular, according to the second invention of the present application, the supply time of the mixing water can be adjusted by switching between the first liquid supply path and the second liquid supply path.

[0018] In particular, according to the third aspect of the present invention, the supply time of the mixing water can be extended when the second liquid feed path is selected.

[0019] In particular, according to the fourth aspect of the present invention, the second liquid supply path locally discharges mixing water into the mixer body, thereby lengthening the time required for the mixing water to reach the materials in the mixer body, thereby further promoting the flocculation of cement particles. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic diagram of a fresh concrete manufacturing apparatus. [Figure 2] 1 is a flowchart showing a procedure for producing fresh concrete. [Figure 3] FIG. 10 is a diagram schematically illustrating the state of cement particles when the second control is performed. [Figure 4] FIG. 10 is a diagram showing a schematic diagram of adsorption of a chemical admixture onto cement particles on which flocs are not formed in the case of the first control. [Figure 5] FIG. 10 is a diagram showing a schematic diagram of adsorption of a chemical admixture onto cement particles on which flocs F are formed in the case of the second control. [Figure 6] FIG. 10 is a schematic diagram of a fresh concrete manufacturing apparatus according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0022] <1. Configuration of fresh concrete manufacturing equipment> Fig. 1 is a schematic diagram of a fresh concrete manufacturing apparatus 1 for manufacturing fresh concrete (ready mixed concrete). As shown in Fig. 1, the fresh concrete manufacturing apparatus 1 includes a mixer body 10, a mixing blade 20, a motor 30, a first supply device 40, a second supply device 50, and a control unit 90.

[0023] The mixer body 10 is a container capable of containing the materials for fresh concrete. The mixer body 10 is located below the first supply device 40 and the second supply device 50. The mixing blade 20 is disposed within the mixer body 10. The end of the mixing blade 20 is connected to the motor 30. When the motor 30 is operated, the mixing blade 20 rotates due to the power output from the motor 30. This causes the materials contained within the mixer body 10 to be mixed.

[0024] In the example of Fig. 1, two kneading blades 20 that rotate around a horizontal shaft 21 are arranged inside the mixer body 10. However, the number of kneading blades 20 and the orientation of the shaft 21 are not limited to the example of Fig. 1.

[0025] The first supply device 40 is a device that supplies fine aggregate, cement, and coarse aggregate, which are materials for fresh concrete, into the mixer body 10. The first supply device 40 is composed of a weighing scale, a hopper, etc. In accordance with a control signal input from the control unit 90, the first supply device 40 can supply the fine aggregate, cement, and coarse aggregate to the mixer body 10 at a specified timing and in a specified amount, respectively.

[0026] The second supply device 50 is a device that supplies mixing water and admixtures, which are ingredients of fresh concrete, into the mixer body 10. As shown in FIG. 1 , the second supply device 50 has a water tank 51, an admixture metering device 52, a water metering device 53, and a liquid delivery section 60.

[0027] The water tank 51 is a tank for storing mixing water before it is measured. The mixing water is stored inside the water tank 51. The mixing water is, for example, tap water, groundwater, or river water. However, the mixing water may be a mixture of water from any of these suitable water sources and recovered water (such as the supernatant of concrete sludge).

[0028] The water tank 51 and the water metering device 53 are connected via a pipe 511. The pipe 511 is provided with a valve 512. The valve 512 is electrically connected to the control unit 90. When the control unit 90 opens the valve 512, mixing water is supplied from the water tank 51 to the water metering device 53 through the pipe 511.

[0029] The admixture metering device 52 is a device that stores the admixture before supply, and measures the required amount of admixture and supplies it to the water metering device 53. The admixture (chemical admixture) in this embodiment is an industrial chemical that adsorbs to cement particles and has the effect of causing the cement particles to repel each other.

[0030] The admixture used in this embodiment is a water-reducing agent, a high-performance water-reducing agent, or a combination thereof, which is a type of surfactant. The admixture mainly contains, for example, a polycarboxylic acid-based water-reducing agent with steric hindrance, or a naphthalene-based or melamine-based water-reducing agent with electrostatic repulsion. The base of the admixture may be, for example, polystyrene sulfonate, polycarboxylate, naphthalene sulfonate, or melamine sulfonate.

[0031] The admixture metering device 52 and the water metering device 53 are connected via a pipe 521. A valve 522 is provided in the pipe 521. The valve 522 is electrically connected to the control unit 90. When the control unit 90 opens the valve 522, the admixture is supplied from the admixture metering device 52 through the pipe 521 to the water metering device 53.

[0032] The water metering device 53 is a device that stores the mixing water supplied from the water tank 51 and the admixture supplied from the admixture metering device 52, and also measures the mixing water containing the admixture. Hereinafter, the mixing water containing the admixture will be simply referred to as "mixing water."

[0033] The liquid supply unit 60 is a piping unit that supplies a predetermined amount of mixing water appropriate for the mix of fresh concrete to be produced from the water metering device 53 to the mixer body 10. As shown in Fig. 1, the liquid supply unit 60 has a first supply pipe 611, a first valve 612, a pump 613, a first discharge pipe 614, a second supply pipe 621, and a second valve 622.

[0034] The first supply pipe 611 is a pipe that connects the water metering device 53 and the first discharge pipe 614. The upstream end of the first supply pipe 611 is connected to the water metering device 53. The downstream end of the first supply pipe 611 is connected to the first discharge pipe 614. A first valve 612 and a pump 613 are provided on the first supply pipe 611. The first discharge pipe 614 is arranged inside the mixer body 10. More specifically, the first discharge pipe 614 is arranged along the periphery of the upper end of the mixer body 10. The first discharge pipe 614 has a plurality of discharge ports 610.

[0035] The first valve 612 and the pump 613 are electrically connected to the control unit 90. When the control unit 90 opens the first valve 612 and drives the pump 613, the mixing water is sent from the water metering device 53 through the first supply piping 611 to the first discharge pipe 614. Then, due to the pressure of the pump 613, the mixing water is discharged in a shower-like manner from the multiple discharge ports 610 of the first discharge pipe 614 into the inside of the mixer body 10.

[0036] The second supply pipe 621 is a pipe for supplying mixing water from the water metering device 53 without using the pump 613. An upstream end of the second supply pipe 621 is connected to the water metering device 53. A downstream end of the second supply pipe 621 is connected to a portion of the first supply pipe 611 that is downstream of the pump 613. The inner diameter of the second supply pipe 621 is smaller than the inner diameter of the first supply pipe 611. In addition, a second valve 622 is provided on the second supply pipe 621.

[0037] The second valve 622 is electrically connected to the control unit 90. When the control unit 90 opens the second valve 622, mixing water is supplied from the water metering device 53 through the second supply pipe 621 to the first supply pipe 611. Here, the water metering device 53 is disposed above the mixer body 10. For this reason, the mixing water flows out into the second supply pipe 621 due to its own weight. Then, the mixing water supplied from the second supply pipe 621 through the first supply pipe 611 to the first discharge pipe 614 is slowly supplied into the inside of the mixer body 10 from the multiple discharge ports 610 of the first discharge pipe 614.

[0038] That is, the liquid supply unit 60 of this embodiment has a first liquid supply path 61 that supplies mixed water through the first supply pipe 611 without using the second supply pipe 621, and a second liquid supply path 62 that supplies mixed water using the second supply pipe 621. The liquid supply unit 60 switches between the first liquid supply path 61 and the second liquid supply path 62 by selectively opening either the first valve 612 or the second valve 622.

[0039] The second supply pipe 621 has a smaller diameter than the first supply pipe 611. Therefore, the flow path resistance of the second supply pipe 621 is larger than the flow path resistance of the first supply pipe 611. Furthermore, while the pump 613 is used to transfer the liquid through the first liquid transfer path 61, the liquid is transferred by gravity without using the pump 613 when transferred through the second liquid transfer path 62. At this time, under the same formulation, the amount of mixing water to be transferred is fixed to a predetermined amount, so the time required for transferring the liquid through the second liquid transfer path 62 is longer than the time required for transferring the liquid through the first liquid transfer path 61. In this way, the liquid transfer unit 60 is provided with a supply time adjustment mechanism that adjusts the time required to supply a unit amount of mixing water (supply time) by switching between the liquid transfer paths 61 and 62.

[0040] In this embodiment, the supply time of mixing water through the first liquid supply path 61 is set as the standard, and by using the second liquid supply path 62 under a predetermined blending condition, the supply time of mixing water can be extended. That is, the supply time adjustment mechanism adjusts the supply time per unit amount of mixing water so as to extend it relative to a predetermined standard supply time. The extended supply time is, for example, at least twice the standard supply time, more preferably at least five times, and even more preferably at least ten times. In this embodiment, the standard supply time is set to 5 seconds, and the extended supply time is set to 60 seconds (12 times the standard supply time).

[0041] As will be understood by those skilled in the art, the amount of mixing water is strictly controlled in the mix design of fresh concrete, and the total amount cannot be increased or decreased under a given mix ratio. In other words, extending the supply time of mixing water relative to the standard supply time does not mean increasing the total amount of mixing water. Therefore, adjusting the supply time of mixing water by the supply time adjustment mechanism is synonymous with adjusting the supply time per unit amount, and includes both extending the supply time relative to the standard supply time and shortening the extended supply time back to the standard supply time.

[0042] Furthermore, the standard supply time is a predetermined time that corresponds to the batch cycle (the time required to produce one batch of fresh concrete), and it is recommended that the standard supply time be within 5 seconds, or at most 10 seconds. In this case, the lower limit of the batch cycle is determined by the mix ratio and the performance of the mixer. Therefore, those skilled in the art who wish to shorten the batch cycle as much as possible may consider adjusting the time by shortening some of the manufacturing processes, such as the individual mixing processes, so that the total manufacturing time falls within the batch cycle when the supply time of mixing water is extended relative to the standard supply time. Such time adjustments for each process that take the batch cycle into account will be discussed later.

[0043] The control unit 90 is a unit that controls the operation of each part of the fresh concrete manufacturing apparatus 1. The control unit 90 is configured, for example, by a computer having a processor such as a CPU, a memory such as RAM, and a storage unit such as a hard disk drive. The control unit 90 outputs control signals to each part of the fresh concrete manufacturing apparatus 1 in accordance with a computer program and various set values. As a result, materials are supplied from the first supply device 40 and the second supply device 50 to the mixer body 10, and the mixing blades 20 rotate within the mixer body 10 to mix the materials.

[0044] <2. Manufacturing method of fresh concrete> Next, a description will be given of a method for producing fresh concrete using the above-mentioned fresh concrete production apparatus 1. Fig. 2 is a flowchart showing the procedure for producing fresh concrete. The production procedure in Fig. 2 is realized by the above-mentioned control unit 90 controlling the operations of the motor 30, the first supply device 40, and the second supply device 50.

[0045] This fresh concrete manufacturing apparatus 1 can manufacture fresh concrete by two types of methods: first control and second control. The first control and second control differ only in the method of supplying mixing water by the second supply device 50 in the first mixing step S3, which will be described later.

[0046] When producing fresh concrete, first, fine aggregate and cement are charged from the first supply device 40 into the mixer body 10 (step S1: first material charging step). The fine aggregate is an aggregate having a smaller particle size than the coarse aggregate described below.

[0047] Examples of fine aggregates that can be used include natural sand (sea sand, mountain sand), crushed sand, and crushed lime sand. Crushed sand conforming to JIS A 5005:2009 is preferably used, and natural sand conforming to JIS A 5308:2019 is preferably used, but these are merely examples and are not intended to be limiting. Furthermore, the fine aggregate may be recycled aggregate, slag aggregate, or other substitute aggregate. The fine aggregate may be bone dry or may contain surface water. Various cements, such as ordinary cement, high-early-strength cement, moderate-heat cement, and low-heat cement, can be used depending on the blending ratio and application.

[0048] Next, the motor 30 starts to rotate the kneading blade 20 (step S2: start of rotation), whereby the materials that have already been charged into the mixer body 10 start to be kneaded and mixed.

[0049] Simultaneously with or following the start of rotation of the kneading blade 20, the second supply device 50 starts supplying mixing water to the mixer body 10. As a result, the charged materials are mixed while the mixing water is being supplied (Step S3: first kneading step). That is, the execution time of the first kneading step S3 is the same as the supply time of the mixing water.

[0050] When the first control is selected, in the first kneading step S3, the above-described first liquid supply path 61 is used to supply the mixing water to the mixer body 10 in a relatively short standard supply time (for example, about 5 seconds) using the pressure of the pump 613. On the other hand, when the second control is selected, the above-described second liquid supply path 62 is used to supply the mixing water to the mixer body 10 over a relatively long extended supply time (for example, 60 seconds).

[0051] Even after the supply of mixing water is completed and the first kneading step S3 is finished, the control unit 90 continues to rotate the kneading blade 20 by the motor 30 to further knead the materials (step S4: second kneading step). The control unit 90 performs kneading so that the total time of the first kneading step S3 and the second kneading step S4 is a predetermined time within a predetermined batch cycle.

[0052] After the second mixing step S4 is completed, the first supply device 40 then charges coarse aggregate (gravel) into the mixer body 10 (step S5: second material charging step). Coarse aggregate is aggregate with a larger particle size than the fine aggregate described above. Various types of coarse aggregate are used, such as crushed stone, natural gravel (such as river gravel), or recycled aggregate. The motor 30 then continues to rotate the mixing blade 20, further mixing the materials (step S6: third mixing step). As a result, fresh concrete consisting of fine aggregate, cement, water, admixtures, and coarse aggregate is produced. The time of the third mixing step S6 is appropriately adjusted by the control unit 90 within a predetermined batch cycle.

[0053] That is, in this embodiment, the control unit 90 controls the rotation of the mixing blade 20 by the motor 30 so that the total mixing time, which is the sum of the times for the first mixing step S3, the second mixing step S4, and the third mixing step S6, falls within a predetermined batch cycle range. In particular, when the second control is performed, the time for the first mixing step S3 increases, so it is preferable to appropriately shorten the time for the second mixing step S4 and / or the third mixing step S6. This makes it possible to prevent an excessive increase in the total mixing time, improving the productivity of the fresh concrete manufacturing apparatus 1.

[0054] In the above-described fresh concrete manufacturing method, the difference between the first control and the second control when the same mix proportion is assumed will be explained below. In the first control, in the first mixing step S3, a predetermined amount of mixing water appropriate for the mix proportion is supplied evenly throughout the mixer body 10 in a short time. Therefore, in the first control, mixing water is supplied sufficiently to the entire cement in a short time. In contrast, in the second control, the amount of the predetermined amount of mixing water supplied per unit time in the first mixing step S3 is less than in the first control. Therefore, in the second control, mixing water is supplied to the cement in small amounts.

[0055] Fig. 3 is a diagram showing a schematic diagram of the state of cement particles when the second control is performed. In the second control, in the initial stage of the first mixing step S3, mixing is performed by the mixing blade 20 with a small amount of mixing water supplied around the cement particles. Then, as shown in Fig. 3, the cement particles aggregate with each other due to the action of the small amount of mixing water, forming flocs F.

[0056] Floc F is an aggregate with an average particle size equal to or larger than the average particle size of cement particles (approximately 10 μm). When cement particles form floc F, the specific surface area of ​​the cement becomes smaller than when floc F is not formed. Floc F comes in a variety of particle sizes, but it is believed that the formation of floc F with particle sizes of approximately several tens of μm can significantly reduce the specific surface area of ​​cement. The mechanism by which floc F is formed is thought to be that, for example, when water is added to cement, a hydration reaction generates positive charges on the surfaces of cement particles, making them unstable and causing the particles to adsorb to each other.

[0057] Fig. 4 is a diagram showing a schematic diagram of adsorption of a chemical admixture onto cement particles on which flocs F are not formed in the first control. Fig. 5 is a diagram showing a schematic diagram of adsorption of a chemical admixture onto cement particles on which flocs F are formed in the second control.

[0058] In the first mixing step S3 of the first control, as shown in Figure 4, the admixture is adsorbed onto individual cement particles without forming flocs F on most of the cement particles. Therefore, in the first mixing step S3 of the first control, excess admixture is unlikely to be produced in the liquid phase.

[0059] In contrast, in the first kneading step S3 of the second control, as shown in Figure 5, the admixture is adsorbed to the cement particles whose specific surface area has been reduced by the formation of flocs F. Therefore, the amount of admixture adsorbed to the cement particles is less in the case of Figure 5 than in the case of Figure 4. As a result, in the first kneading step S3 of the second control, some of the admixture supplied is not adsorbed to the cement particles and remains as excess admixture in the liquid phase.

[0060] The excess admixture contributes to improving the fluidity of the mortar in the second mixing step S4 (for example, the flow value measured using the test method specified in JIS R 5201:2015). Furthermore, the dispersion effect of the excess admixture continues in the third mixing step S6. As a result, the fluidity of the finally produced fresh concrete (for example, the flow value measured using the test method specified in JIS A 1150:2007) is improved. Thus, the fresh concrete manufacturing apparatus 1 can adjust the supply time of mixing water per unit amount by switching between the first control using the first liquid supply path 61 and the second control using the second liquid supply path 62. This allows the fluidity of the produced fresh concrete to be adjusted by switching between the first control using the first liquid supply path 61 and the second control using the second liquid supply path 62.

[0061] That is, the fresh concrete manufacturing apparatus 1 of this embodiment can switch between a first control that does not promote the formation of flocs F and a second control that promotes the formation of flocs F. This allows the control method to be selected depending on the use of the fresh concrete, etc. For example, when producing high-strength concrete, selecting the second control can promote the formation of flocs F and improve the fluidity of the fresh concrete. Note that the switching between the first control and the second control can be performed either automatically or manually (at the discretion of the operator).

[0062] At least a portion of the floc F generated in the first mixing step S3 may be decomposed into multiple cement particles in the second mixing step S4 and the third mixing step S6. However, it is believed that the decomposed cement particles also become well dispersed due to the adsorption of the excess admixtures described above. Alternatively, in the second mixing step S4 and the third mixing step S6, the mixing water and cement particles come into contact with each other, and hydration products are sequentially generated. If the admixtures already adsorbed to the cement particles (or hydration products) are absorbed into these hydration products, the dispersing effect of the admixtures is weakened. However, it is believed that the excess admixtures described above sequentially adsorb onto the surfaces of the newly formed hydration products, thereby maintaining the hydration products in a dispersed state. As a result, it is believed that the fluidity of fresh concrete can be improved compared to when there is no excess admixture.

[0063] When the second liquid supply path 62 is used to supply the mixing water, the liquid supply path may be switched from the second liquid supply path 62 to the first liquid supply path 61 in the final stage of the first kneading step S3. In this way, at the end of the first kneading step S3, the mixing water can be forcefully discharged from the first discharge pipe 614 using the pump 613. This makes it possible to reduce the amount of mixing water remaining in the first discharge pipe 614 after the end of the first kneading step S3.

[0064] <3. Modifications> Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. Below, several modifications will be described, focusing on the differences from the above embodiment.

[0065] <3-1. First modified example> Fig. 6 is a schematic diagram of a fresh concrete manufacturing apparatus 1 according to a first modified example. In the above embodiment, regardless of whether the first liquid supply path 61 or the second liquid supply path 62 is selected, mixing water is discharged from the first discharge pipe 614 into the mixer body 10. In contrast, in the example of Fig. 6, the first discharge pipe 614 that discharges mixing water from the first liquid supply path 61 into the mixer body 10 and the second discharge pipe 623 that discharges mixing water from the second liquid supply path 62 into the mixer body 10 are provided separately. The first discharge pipe 614 is equivalent to the first discharge pipe 614 in the above embodiment.

[0066] In this embodiment, the second supply pipe 621 does not merge with the first supply pipe 611. A second discharge pipe 623 is provided at the downstream end of the second supply pipe 621. The second discharge pipe 623 is a pipe-shaped nozzle that discharges mixing water from a single discharge port 620, rather than discharging mixing water in a shower-like manner from multiple discharge ports 610 like the first discharge pipe 614. In this way, even when the second liquid sending path 62 is used, it is possible to prevent mixing water from remaining in the second discharge pipe 623 after the end of the first kneading step S3.

[0067] Furthermore, the second discharge pipe 623 locally discharges the mixing water into the mixer body 10. This increases the time required for the mixing water to reach all of the material, including the cement particles, inside the mixer body 10. As a result, the formation of flocs F by the cement particles can be further promoted.

[0068] <3-2. Other variations> In the above embodiment, the supply time of the mixing water to the mixer body 10 is adjusted by switching between the first liquid supply path 61 and the second liquid supply path 62. However, the supply time of the mixing water to the mixer body 10 may be adjusted by a method other than switching the liquid supply paths. For example, the supply time of the mixing water to the mixer body 10 may be adjusted by adjusting the output of the pump 613 of the first liquid supply path 61, without providing the second liquid supply path 62. Also, the supply time of the mixing water to the mixer body 10 may be adjusted by adjusting the opening of the first valve 612 of the first liquid supply path 61, without providing the second liquid supply path 62.

[0069] The mix proportions of fresh concrete targeted by the present technology are not limited to the above-described embodiments, and the present technology can be applied to any desired mix proportions in which the floc-forming action can have a beneficial effect on the properties of fresh concrete.

[0070] In this case, the type of admixture is not limited to the above embodiment, and various chemical admixtures or admixture materials (special materials included in the mixed volume) may be used in combination with the admixtures appearing in the above embodiment, or alone.

[0071] Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate within the scope of not causing any contradiction. [Industrial Applicability]

[0072] INDUSTRIAL APPLICABILITY The present invention can be used in an apparatus and method for producing fresh concrete. [Explanation of symbols]

[0073] 1. Fresh concrete manufacturing equipment 10 Mixer body 20 Mixing blade 30 motor 40 1st supply device 50 Second supply device 51 Aquarium 52 Admixture metering device 53 Water metering device 60 Liquid delivery unit 61 First liquid transfer path 62 Second liquid transfer path 90 Control Unit 610 Discharge port 611 1st supply piping 612 First Valve 613 Pump 614 1st discharge pipe 620 Outlet 621 2nd supply piping 622 Second Valve 623 2nd discharge pipe F Frock

Claims

1. A fresh concrete manufacturing apparatus, a mixer body containing a material including cement particles; a mixing blade for mixing materials in the mixer body; a liquid supply unit that supplies a predetermined amount of mixing water to the mixer body; Equipped with The liquid delivery unit is a supply time adjusting mechanism for adjusting the supply time of the predetermined amount of mixing water; A fresh concrete manufacturing apparatus having the above.

2. The fresh concrete manufacturing apparatus according to claim 1, The liquid delivery unit is a first liquid supply path for supplying mixing water by a pump; a second liquid supply path that supplies the mixing water by its own weight without using the pump; and The fresh concrete manufacturing apparatus, wherein the supply time adjustment mechanism switches between the first liquid supply path and the second liquid supply path.

3. The fresh concrete manufacturing apparatus according to claim 2, A fresh concrete manufacturing apparatus, wherein the second liquid supply path includes a pipe having a smaller diameter than the first liquid supply path.

4. The fresh concrete manufacturing apparatus according to claim 2 or 3, The second liquid transfer path is A discharge port for locally discharging mixing water into the mixer body A fresh concrete manufacturing apparatus having the above.

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