Concrete manufacturing method and concrete manufacturing apparatus

Abstract

To provide a method and an apparatus for producing concrete by which the amount of dust generated in a mixer is reduced, the loss of silica fume is reduced and the operation of a dust collector is minimized.SOLUTION: The concrete is manufactured by spraying mist from a mist spraying means 9 into a mixer 2 for kneading a raw material containing silica fume in a mist spraying process. The mist spraying means 9 sprays mist using the first compound water before the mixed kneading water feeding means 8 feeds the second compound water into the mixer 2 as the mixed kneading water.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a concrete manufacturing method and a concrete manufacturing apparatus for manufacturing concrete containing silica fume using a mixer. [Background technology]

[0002] In a batcher plant, which is a typical example of a ready-mix concrete manufacturing device, ready-mix concrete is manufactured by kneading materials such as gravel (coarse aggregate), sand (fine aggregate), cement, water, and admixtures in a mixer. In the mixer, dust is generated by the addition and mixing of various materials, so a suction pipe is connected to the mixer and the dust is collected by a dust collector (for example, Patent Document 1).

[0003] Silica fume is sometimes mixed into concrete that requires ultra-high strength, such as concrete that forms segments that serve as linings for large cross-section tunnels (for example, Patent Document 2).

[0004] Silica fume is available in powder, slurry, and granular forms, but powder form, which has good dispersibility, is generally used.

[0005] Silica fume is sometimes pre-blended into cement products, and sometimes added on its own when mixing concrete, but in either case, the particle size of powdered silica fume is extremely fine, about 1 / 100th the size of cement particles, and this results in further dust generation inside the mixer of the batcher plant. Dust generation is particularly noticeable when powdered silica fume is added on its own. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2-265710 [Patent Document 2] Patent No. 7381623 Summary of the Invention [Problem to be solved by the invention]

[0007] Fine dust caused by silica fume is generated inside the mixer, and if this dust is removed with a dust collector as described in Patent Document 1, there is a risk that the amount of silica fume contained in the concrete will decrease. Furthermore, as mentioned above, silica fume is very fine and therefore easily clogs the filters of dust collectors, increasing the amount of work required for maintenance.

[0008] The problem to be solved by the present invention is to provide a concrete manufacturing method and concrete manufacturing apparatus which reduce the amount of dust generated in the mixer, minimize the loss of silica fume, and minimize the operation and maintenance of the dust collector. [Means for solving the problem]

[0009] The invention of claim 1 is a concrete manufacturing method for manufacturing ultra-high strength reinforced concrete segments containing silica fume using a mixer that mixes raw materials, and is characterized by including a mist spraying step that sprays mist inside the mixer.

[0010] The invention of claim 2 is a concrete manufacturing method for manufacturing concrete using a mixer that mixes raw materials, characterized by including a mist spraying step of spraying mist inside the mixer.

[0011] The invention according to claim 3 is the method for producing concrete according to claim 2, characterized in that the raw material contains silica fume.

[0012] The invention according to claim 4 is the concrete manufacturing method according to any one of claims 1 to 3, characterized in that it further comprises a mixing water introduction step of introducing liquid mixing water into the mixer, and the mist spraying step is started before the mixing water introduction step is started.

[0013] The invention of claim 5 is a method for producing concrete according to any one of claims 1 to 3, characterized in that the raw materials contain water to be mixed into the concrete, the water mixture including a first water mixture used for the mist sprayed in the mist spraying step and a second water mixture used as liquid water mixture, the method further comprising a water mixture introduction step of introducing the second water mixture into the mixer as water mixture, and the mist spraying step involves spraying mist using the first water mixture.

[0014] The invention according to claim 6 is the concrete manufacturing method according to claim 5, characterized in that the mist spraying step is started before the mixing water introducing step is started.

[0015] The invention of claim 7 is the concrete manufacturing method described in claim 1 or claim 3, characterized in that it includes a silica fume adding step of adding the silica fume to the mixer, and the mist spraying step is started after the silica fume adding step is started.

[0016] The invention of claim 8 is a concrete manufacturing apparatus having a mixer for mixing raw materials and for manufacturing concrete for ultra-high strength reinforced concrete segments containing silica fume, characterized in that it is equipped with a mist spraying means for spraying mist inside the mixer.

[0017] The invention of claim 9 is a concrete manufacturing apparatus for producing concrete having a mixer for mixing raw materials, characterized in that it is equipped with a mist spraying means for spraying mist inside the mixer.

[0018] A tenth aspect of the present invention is the concrete manufacturing apparatus according to the ninth aspect, wherein the raw material contains silica fume.

[0019] The invention according to claim 11 is the concrete manufacturing apparatus according to any one of claims 8 to 10, characterized in that it comprises a mixing water injecting means for injecting liquid mixing water into the mixer, and the mist spraying means sprays mist before the mixing water injecting means injects the liquid mixing water.

[0020] The invention of claim 12 is a concrete manufacturing apparatus according to any one of claims 8 to 10, characterized in that the raw materials include water to be mixed into the concrete, the water mixture having a first water mixture used for the mist sprayed by the mist spraying means and a second water mixture used as liquid water mixture, the apparatus further comprising water mixture feeding means for feeding the second water mixture into the mixer as water mixture, and the mist spraying means sprays mist using the first water mixture.

[0021] The invention of claim 13 is the concrete manufacturing apparatus described in claim 12, characterized in that the mist spraying means starts spraying mist before the mixing water supplying means starts supplying the second mixing water into the mixer as mixing water.

[0022] The invention of claim 14 is the concrete manufacturing apparatus described in claim 8 or claim 10, characterized in that it is provided with a silica fume dosing means for dosing the silica fume into the mixer, and the mist spraying means starts spraying mist after the silica fume dosing means has dosed the silica fume into the mixer.

[0023] The invention according to claim 15 is the concrete manufacturing apparatus according to any one of claims 8 to 10, characterized in that it has an openable / closable lid capable of covering the spray nozzle of the mist spraying means. [Effects of the Invention]

[0024] According to the present invention, even if dust is generated when cement and finer silica fume are mixed in a mixer, the dust is adsorbed by the mist sprayed into the mixer, falls down, and is mixed into the concrete. This reduces the amount of cement and silica fume that remains inside the mixer and is not mixed into the concrete, thereby reducing the loss rate of cement and silica fume. Even when a dust collector is used in combination, the mist removes dust from inside the mixer, reducing clogging of the dust collector filter and reducing the effort required for dust collector maintenance. Since less dust is dispersed inside the mixer, it is easier to see the situation without being obstructed by dust, even when a camera is installed inside the mixer or when inspecting visually.

[0025] In addition, the raw materials contain mixing water that has a first mixing water used for the mist and a second mixing water used as liquid mixing water, so the water content of the concrete does not become too high, as would be the case if water for the mist were added separately from the mixing water mixed into the concrete, and the appropriate amount of water can be maintained.

[0026] In addition, by starting the spraying of the mist before the introduction of the mixed kneading water, it is possible to suppress the generation of dust during dry kneading before the introduction of the mixed kneading water.

[0027] In addition, if the device has an openable / closable lid that can cover the spray nozzle of the mist spraying means, by covering the spray outlet when mist is not being sprayed, it is possible to prevent dust from adhering to the spray nozzle and clogging it. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a plan view of a concrete manufacturing apparatus showing an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Figure 3] 2 is a cross-sectional view of FIG. 1 taken along line B-B. [Figure 4]FIG. 2 is a plan view of the mist spraying means according to the embodiment of the present invention. [Figure 5] FIG. 2 is a cross-sectional view of a mist spraying means according to an embodiment of the present invention. [Figure 6] 10A and 10B are diagrams illustrating the dust adsorption effect of mist. [Figure 7] 1 is a diagram showing an example of a flow of a concrete manufacturing method using a concrete manufacturing apparatus according to an embodiment of the present invention. FIG. [Figure 8] 1 is a process diagram for producing ultra-high strength concrete according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiments.

[0030] Figure 1 is a plan view of a concrete manufacturing apparatus, Figures 2 and 3 are cross-sectional views of the concrete manufacturing apparatus, Figure 4 is a plan view of a mist spraying means, Figure 5 is a cross-sectional view of a mist spraying means, Figure 6 is a diagram explaining the dust adsorption effect of mist, Figure 7 is a diagram showing an example of the flow of a concrete manufacturing method using a concrete manufacturing apparatus, and Figure 8 is a process diagram for manufacturing ultra-high strength concrete.

[0031] In this embodiment, the concrete manufacturing apparatus 1 is an apparatus for manufacturing ultra-high strength concrete for forming concrete segments that will become the tunnel lining of a shield tunnel.

[0032] Ultra-high strength concrete is made by adding powdered silica fume, which accounts for more than 10% of the cement weight, to the cement as raw materials, and further mixing coarse aggregate (gravel), fine aggregate (sand), reinforcing fiber, expansion agent, admixture, etc. Ultra-high strength concrete containing silica fume has a design standard strength of, for example, 80 N / mm 2 ~120N / mm 2 This refers to reinforced concrete to this extent.

[0033] As shown in Figures 1 to 3, the concrete manufacturing apparatus 1 includes a mixer 2, a cement chute 3, an admixture chute 4, a fine aggregate chute 5, a coarse aggregate chute 6, a dust collecting means 7, a mixing water introducing means 8, and a mist spraying means 9.

[0034] The mixer 2 is a device for mixing the concrete ingredients, and is a so-called twin-shaft forced mixing mixer, with a pair of parallel mixer blades 20 for mixing rotatably mounted on the bottom of the mixer 2. The rotation of the mixer blades 20 is driven by a drive source (not shown).

[0035] An openable and closable discharge port 22 is formed at the bottom end of the mixer 2, so that the concrete that has been mixed can be supplied to a mixer truck or the like (not shown).

[0036] A camera 21 is installed in the center of the top surface of the mixer 2 to visually check the internal conditions of the mixer 2.

[0037] The cement chute 3 has a downstream end connected to an opening at the top of the mixer 2 and an upstream end connected to a cement silo (not shown).

[0038] A measuring device (not shown) is installed between the cement silo and the cement chute 3, and the cement from the cement silo is measured, and a predetermined amount is poured into the mixer 2 via the cement chute 3. These devices that feed cement into the mixer 2 correspond to cement feeding means.

[0039] The admixture chute 4 has its downstream end connected to the opening at the top of the mixer 2 and its upstream end connected to a silica fume silo (not shown).

[0040] A weighing device (not shown) is installed between the silica fume silo and the admixture chute 4, and the powdered silica fume from the silica fume silo is weighed and a predetermined amount is fed into the mixer 2 via the admixture chute 4. These devices that feed silica fume into the mixer 2 correspond to the silica fume feeding means.

[0041] The fine aggregate chute 5 has a downstream end connected to an opening at the top of the mixer 2 and an upstream end connected to a fine aggregate supply device (not shown).

[0042] The fine aggregate supply device is equipped with a fine aggregate measuring device, which measures fine aggregate from a fine aggregate storage section and feeds a predetermined amount into the mixer 2 through a fine aggregate chute 5. These devices that feed fine aggregate into the mixer 2 correspond to fine aggregate feeding means.

[0043] The downstream end of the coarse aggregate chute 6 is connected to an opening at the top of the mixer 2, and the upstream end is connected to a coarse aggregate supply device (not shown).

[0044] The coarse aggregate supply device is equipped with a coarse aggregate measuring device, which measures the coarse aggregate from the coarse aggregate storage section and feeds a predetermined amount into the mixer 2 through the coarse aggregate chute 6. These devices that feed the coarse aggregate into the mixer 2 correspond to the coarse aggregate feeding means.

[0045] In addition to the above, the mixer 2 is provided with an admixture feeding means, an expansion agent feeding means, a reinforcing fiber feeding means, etc., which are not shown in the figure, and are configured so that predetermined amounts of admixture, expansion agent, reinforcing fiber, etc. are appropriately fed into the mixer 2.

[0046] The dust collecting means 7 is a device that sucks in the air inside the mixer 2 together with dust and removes the dust with a built-in filter, and is provided with an intake duct 70 and a dust collector 71.

[0047] One end of the intake duct 70 is connected to an opening at the top of the mixer 2, and the other end is connected to a dust collector 71, and dust inside the mixer 2 is transported to the dust collector 71 via the intake duct 70.

[0048] The dust collector 71 collects and treats dust inside the mixer 2 through the intake duct 70. The dust collector 71 is, for example, a bag filter type dust collector.

[0049] The mixing / kneading water introducing means 8 includes a water supply pipe 80 , a water tank 81 , a water supply amount measuring device 82 , and a water supply pump 83 .

[0050] The water supply pipe 80 has an upstream end connected to a water tank 81 and a downstream end connected to an opening at the top of the mixer 2 .

[0051] The mixing water supplying means 8 supplies water stored in a water tank 81 by driving a water supply pump 83 into the mixer 2 via a water supply pipe 80 as liquid mixing water to be mixed into concrete.

[0052] The water supply amount measuring device 82 measures the amount of water supplied into the mixer 2 through the water supply pipe 80, and when the measured amount of water reaches a predetermined amount, it stops the water supply pump 83, thereby stopping the water supply.

[0053] The mist spraying means 9 is a device that sprays water supplied from a mist water supply means (not shown) into the mixer 2 as an electrically charged mist, and is installed at two locations on both ends of a diagonal line on the upper wall 2a of the mixer 2. The mist water supply means may be configured to supply water from a water tank 81.

[0054] As shown in Figures 4 and 5, the mist spraying means 9 comprises a water supply pipe 90 connected to a mist water supply means (not shown), a power supply unit 91 connected to a power supply unit (not shown), a spray nozzle 92, a dielectric electrode unit 93, and a casing 94.

[0055] The spray nozzles 92 are fixed to a frame 90a supported by the water supply pipe 90, and four of them are installed at equal intervals around the periphery of the lower surface of the mist spraying means 9 with their spray ports 92a facing downward.

[0056] Water supplied to water supply pipe 90 from mist water supply means (not shown) is divided by a branch pipe (not shown) into four spray nozzles 92, and spray nozzles 92 spray the supplied water radially downward, for example, as mist with particle sizes of approximately 25 to 300 μm. The mist water supply means is equipped with a water supply amount meter, a supply pump, and a control unit that adjusts the amount and time of mist spraying, allowing it to spray an appropriate amount of mist for the dust being generated.

[0057] The dielectric electrode portion 93 is formed by coating a conductive metal with an insulating material, and is disposed downstream of the spray nozzle 92 so as to surround the spray port 92 a of the spray nozzle 92 . An electric field is formed by passing a high-voltage current from the power supply unit 91 to the dielectric electrode unit 93, and the water film sprayed by the spray nozzle 92 is charged as it passes between the dielectric electrode units 93. The charged water film is then sprayed in the form of a mist, and the charged mist is sprayed into the mixer 2.

[0058] The casing 94 has a side wall 94 a and an openable / closable lid 94 b , and is provided in the mixer 2 so as to cover the water supply pipe 90 , the power supply unit 91 , the spray nozzle 92 and the dielectric electrode unit 93 .

[0059] The side wall 94a surrounds the water supply pipe 90, the power supply section 91, the spray nozzle 92 and the dielectric electrode section 93 in a plan view, and extends downward from the inner surface of the upper wall 2a of the mixer 2 to a position beyond the dielectric electrode section 93.

[0060] The opening / closing lid 94b is attached to the lower end of the side wall 94a via a hinge 94c, and the opening formed at the lower end of the side wall 94a can be opened or closed by a drive control unit not shown.

[0061] When the opening / closing lid 94b is open (the state shown by the solid line in Figure 5), the spray nozzle 92 and the dielectric electrode part 93 are exposed inside the mixer 2 and can spray mist, and when the opening / closing lid 94b is closed (the state shown by the dashed line in Figure 5), the spray nozzle 92 and the dielectric electrode part 93 are covered by the casing.

[0062] When the mist spraying means 9 is not spraying mist, the opening / closing lid 94b is closed to cover the spray nozzle 92 and the dielectric electrode part 93, thereby preventing problems caused by dust adhering to the spray nozzle 92a and the electrode.

[0063] As shown in FIG. 6, water particles a of the charged mist and dust particles b floating inside the mixer 2 are attracted to each other by Coulomb force, and the dust particles b are adsorbed by the water particles a and fall. Therefore, the amount of dust b floating inside the mixer 2 decreases, the amount of dust clogging the filter of the dust collector 71 decreases, and the situation inside the mixer 2 can be easily observed by the camera 21.

[0064] The mixing water to be mixed into the concrete mixed in the mixer 2 includes the first mixing water used for the mist sprayed from the mist spraying means 9 and the second mixing water introduced from the mixing water introduction means 8 as liquid mixing water.

[0065] The amount of water mixed is preset, so if you add mist separately from the mixed water, the amount of water will be too much. Therefore, the amount of the second water blend used as the mixing water is the amount of water obtained by subtracting the amount of the first water blend used for the mist from the amount of the water blend.

[0066] The mixing and kneading water supplying means 8 is equipped with a control unit (not shown), and the amount of water used for the mist sprayed by the mist spraying means 9 is deducted from the first blended water to set the second blended water, and when the amount of water measured by the water supply amount measuring device 82 reaches the set second blended water, the water supply is stopped.

[0067] An example of the flow of a method for manufacturing one batch of concrete using the concrete manufacturing apparatus 1 will be described below with reference to FIG.

[0068] In step ST1, the mixer blades 20 of the empty mixer 2 start to rotate. Next, the dry mixing step ST2, the mortar mixing step ST3, and the mixing and mixing step ST4 are carried out in this order.

[0069] Next, in step ST5, the discharge port 22 of the mixer 2 opens and the mixed concrete is discharged into a mixer truck or the like, and then in step ST6, the rotation of the mixer blade 20 of the mixer 2 is stopped, ending the flow of one batch.

[0070] The dry mixing process in step ST2 includes a cement addition process, a silica fume addition process, and a fine aggregate addition process. In other words, in the dry mixing process, relatively fine raw materials are added and mixed without adding mixing water.

[0071] In the cement charging step, a predetermined amount of cement is charged into the mixer 2 through the cement chute 3 and mixed.

[0072] In the silica fume introduction step, a predetermined amount of silica fume is introduced into the mixer 2 through the admixture chute 4 and mixed.

[0073] In the fine aggregate charging step, a predetermined amount of fine aggregate is charged into the mixer 2 through the fine aggregate chute 5 and mixed.

[0074] The cement addition process, silica fume addition process, and fine aggregate addition process may be carried out in any order, but in order to prevent the cement and silica fume from being blown up by the paddles (agitating blades) of the mixer blade 20, it is desirable to carry out the cement addition process and silica fume addition process in parallel after the start of the fine aggregate addition process.

[0075] The mortar mixing step of step ST3 includes a mixing water introduction step in which mixing water is introduced into the dry-mixed raw materials and mixed.

[0076] In the mixing / kneading water introducing step, a predetermined amount of second mixing water is introduced into the mixer 2 by the mixing / kneading water introducing means 8 and mixed therein.

[0077] In the mixing and kneading step of step ST4, a coarse aggregate adding step is carried out in which coarse aggregate is added to and mixed with the mortar-kneaded raw material.

[0078] In the coarse aggregate charging step, a predetermined amount of coarse aggregate is charged into the mixer 2 through the coarse aggregate chute 6 and mixed.

[0079] In addition, there are processes such as an expansion agent addition process, an admixture addition process, and a reinforcing fiber addition process in which the raw materials such as expansion agents, admixtures, and reinforcing fibers are added and mixed. These are adopted as needed and are carried out in parallel with the dry mixing process, mortar mixing process, and mixing and kneading process as appropriate.

[0080] In the expansion agent introduction step, a predetermined amount of expansion agent is introduced into the mixer 2 by an expansion agent introduction means (not shown) and mixed. The expansion agent introduction step is preferably carried out in parallel with the dry mixing step in order to efficiently mix the powder material in the same way as cement and silica fume.

[0081] In the admixture introduction step, a predetermined amount of admixture is introduced into the mixer 2 by an admixture introduction means (not shown) and mixed. The admixture introduction step is preferably carried out in parallel with the mortar mixing step, so that the liquid admixture is introduced simultaneously with the mixing water and mixed efficiently.

[0082] In the reinforcing fiber introduction step, a predetermined amount of reinforcing fibers is introduced into the mixer 2 by a reinforcing fiber introduction means (not shown) and mixed. The reinforcing fiber introduction step is preferably carried out in parallel with the mixing and kneading step, since adding the reinforcing fibers simultaneously with the coarse aggregate allows for efficient mixing.

[0083] In this flow, a mist spraying step STM is performed. In the mist spraying step STM, mist is sprayed from the mist spraying means 9 into the mixer 2 using the first blended water, and the mixture is mixed.

[0084] The mist spraying step STM is performed at an appropriate timing depending on the state of dust generated inside the mixer 2. The mist spraying step STM is performed, for example, from before the start of the dry kneading step to the end of the mixing and kneading step.

[0085] The mist spraying step STM is preferably started before the mixing / kneading water adding step in which the second blending water is added, since dust will already be generated inside the mixer 2.

[0086] It is desirable to start the mist spraying process STM simultaneously with or after the dry mixing process, since this allows the mist to be sprayed as soon as dust is generated inside the mixer 2. It is particularly effective to start the mist spraying process STM simultaneously with or after the silica fume addition process, which generates fine dust particles.

[0087] The mist spraying step STM may be performed in parallel with the mortar mixing step or the mixing and kneading step, as long as dust is generated in the mixer 2. The mist spraying step STM may also be started before the dry kneading step, so that the mist is sprayed into the mixer, and then the dry kneading step is performed.

[0088] FIG. 8 shows a specific example of the flow and mix for manufacturing ultra-high strength concrete segments. In the following explanation, the input amount of raw material is 1m 3 This is based on the assumption that the concrete is produced in one batch.

[0089] In this example, the dry mixing step is carried out for 30 seconds, the mortar mixing step for 60 seconds, and the mixing and mixing step for 240 seconds in this order.

[0090] First, at the start of production, the mixer blade 20 starts to rotate, and the fine aggregate charging process starts. 3 The fine aggregate is added within 10 seconds (up to 10 seconds after production begins).

[0091] When half of the fine aggregate has been added (5 seconds after production begins), the cement addition process, silica fume addition process, and expansion agent addition process begin, and the total weight is 570 kg / m 3 of cement, 110 kg / m 3 of powdered silica fume and 30 kg / m 3 The leavening agent is added over a 10-second period, and the dry kneading process is carried out for 30 seconds (until 30 seconds after the start of production).

[0092] The mist spraying process begins simultaneously with the completion of the cement addition process, silica fume addition process, and expansion agent addition process (15 seconds after the start of production), and continues for 30 seconds (until 45 seconds after the start of production).

[0093] The amount of mist sprayed is set based on experience, testing, etc. as appropriate depending on the dust generated, and in this example, the amount of water A (amount of first blended water) is set to, for example, 0.276 L (kg). In this case, the mist spraying means 9 has four spray nozzles 92, with a spray rate of 0.069 L / min per spray nozzle, and since two mist spraying means 9 are installed, the amount of mist sprayed is 0.552 L / min, and the mist spray time is set to 0.276 L ÷ 0.552 L / min = 30 seconds.

[0094] Dry mixing, in which fine aggregate, cement, silica fume, and an expansion agent are mixed with the mixer blade 20, tends to generate a large amount of dust, but the mist spraying means 9 sprays mist, so the dust is adsorbed by the mist and falls, reducing the amount of dust floating inside the mixer 2.

[0095] The mixing water addition process and admixture addition process were started 15 seconds after the mist spraying process started (30 seconds after the start of production), and the mixing water and 10.2 kg / m of the second mixing water were added. 3 Each of the admixtures is added to mixer 2 for 10 seconds.

[0096] The amount of water mixed into the concrete is 170 L / m 3However, since the first blended water used as mist is A (0.276 L), the amount of second blended water used as liquid mixing water is the amount of blended water 170 L minus A (0.276 L).

[0097] The mist spraying process is carried out from 15 seconds after the start of production until 45 seconds after the start of production, and is therefore carried out in parallel with the dry mixing process and the mortar mixing process.

[0098] The dust collector 71 may be started at the same time as the mist spraying process is completed (45 seconds after the start of production) and may be operated until the mortar mixing process is completed (90 seconds after the start of production) to suck up the dust inside the mixer 2. It is desirable to minimize the use of the dust collector 71, and the operation of the dust collector 71 can be reduced by the amount of time required for the mist spraying process.

[0099] The dust collector 71 may be operated until the mixing and kneading process is completed (up to 330 seconds after the start of production). When the operation of the dust collector 71 and the mist spraying process are carried out in parallel, the blending of the raw materials may be adjusted taking into consideration the amount of mist and silica fume dust sucked by the dust collector 71.

[0100] When the mortar mixing process is completed (90 seconds after the start of production), the coarse aggregate addition process begins and the mixing process begins. 3 The coarse aggregate is fed into mixer 2 for 10 seconds.

[0101] At the same time as the start of the mixing and kneading process (90 seconds after the start of production), 2.73 kg / m of reinforcing fiber (polypropylene) PP1 for preventing explosion and 2.73 kg / m of reinforcing fiber (polypropylene) PP2 for preventing peeling were added. 3 Add the ingredients one by one into Mixer 2 over a 90 second period.

[0102] When the dust collector 71 is operated during the mixing and kneading start process, if there is a risk that the reinforcing fibers will be sucked in by the dust collector 71 after the reinforcing fibers are added, the dust collector 71 may be stopped, and then operated again once the reinforcing fibers have mixed into the mixture and there is no longer a risk of them being sucked in.

[0103] The mixing and kneading process is carried out for 240 seconds (330 seconds after the start of production), and then the mixing and kneading process is completed. The discharge port 22 of the mixer 2 opens and the concrete is discharged. Then the rotation of the mixer blade 20 stops, and the production of concrete is completed.

[0104] According to the present invention, even if dust is generated when cement and finer silica fume are mixed in mixer 2, the dust is adsorbed by the mist sprayed into mixer 2, falls down, and is mixed into the concrete. This reduces the amount of cement and silica fume that remains inside the mixer and is not mixed into the concrete, thereby reducing the loss rate of cement and silica fume. Even when the dust collector 71 is used in combination, the dust inside the mixer 2 is removed by mist, so clogging of the filter of the dust collector 71 is reduced, and the effort required for maintenance of the dust collector 71 is reduced. Since less dust is scattered inside the mixer 2, even when a camera 21 is installed inside the mixer 2 or when visual inspection is performed, the situation can be easily viewed without being obstructed by dust.

[0105] The raw materials contain mixing water that has a first mixing water used for the mist and a second mixing water used as liquid mixing water, so that the water content of the concrete does not become too high, as occurs when water for the mist is added separately from the mixing water mixed into the concrete, and the appropriate amount of water added to the concrete can be maintained.

[0106] By starting the spraying of the mist before the introduction of the mixed kneading water, it is possible to suppress the generation of dust during dry kneading before the introduction of the mixed kneading water.

[0107] If the mist spraying means 9 has an open / close lid 94b that can cover the spray nozzle 92, by covering the spray nozzle 92 when mist is not being sprayed, it is possible to prevent dust from adhering to and clogging the spray port 92a.

[0108] [Other Modifications] The present invention is not limited to the above-described embodiment, and may also include the following, for example.

[0109] In this embodiment, powdered silica fume and cement are mixed in the mixer 2 of the batcher plant, but this is not limited to this. So-called premixed silica fume cement, in which silica fume and cement are mixed in advance, may also be used. In this case, the premixed silica fume cement is introduced through a cement chute, and this is also effective against dust that is generated during this process.

[0110] In the embodiment of the present application, the mist sprayed into the mixer is charged, but since uncharged mist also has a certain degree of dust adsorption power, it is also possible to spray uncharged mist into the mixer. In addition, since the positive or negative charge of the generated dust may change depending on the materials mixed into the concrete, it is also possible to provide a charge discrimination means to determine whether the charge of the dust in the mixer is positive or negative, and to charge the mist with an opposite charge to that of the dust.

[0111] In the embodiment of the present application, mist spraying means are provided at two locations on the mixer, and each mist spraying means has four spray nozzles, but the number of mist spraying means and the number of spray nozzles on each mist spraying means may be adjusted as appropriate depending on the size of the mixer, the capacity of the mist spraying means, etc.

[0112] In the embodiment of the present application, the amount of the first compounded water used as mist is subtracted from the compounded amount of the compounded water to determine the amount of the second compounded water added. However, taking into account the amount of mist adhering to the walls of the mixer, a water amount less than that of the first compounded water may also be subtracted from the compounded water to determine the amount of the second compounded water added. In this case, the mist spraying process may be carried out in parallel with the operation of the dust collector. Furthermore, if the amount of water used as the mist does not affect the quality of the concrete, the amount of water used as the mist may be produced without being counted as mixing water.

[0113] The types of ingredients, the amounts of ingredients, and the time required for adding ingredients described in the specific examples of concrete production above can be adjusted as appropriate. It is also possible to adjust the amount of mist sprayed by changing the diameter of the mist spray nozzle, and it is also possible to adjust the particle size of the mist.

[0114] Although the present embodiment relates to the production of ultra-high-strength reinforced concrete segments containing silica fume, the present invention is not limited to this. The present invention is particularly effective in the production of concrete containing powdered silica fume, but it may also be applied to the production of concrete not containing silica fume, and is effective in suppressing dust generated by cement, fine aggregate, etc.

[0115] The technical matters in the embodiments including the modified examples may be combined and applied to other embodiments to form examples. [Explanation of symbols]

[0116] 1. Concrete manufacturing equipment 2. Mixer 2a Upper wall 20 mixer blades 21 Camera 22 Outlet 3 Cement Chute 4 Admixture chute 5 Fine aggregate chute 6 Coarse aggregate chute 7 Dust collection means 70 Intake duct 71 Dust collector 8 Means for adding mixing water 80 Water Supply Pipe 81 Water Tank 82 Water supply measuring device 83 Water Pump 9. Mist spraying means 90 Water supply pipe 90a frame 91 Power supply unit 92 spray nozzle 92a spray nozzle 93 Dielectric electrode part 94 Casing 94a Side wall 94b Opening and closing lid 94c hinge a water particles b Dust

Claims

1. A concrete manufacturing method for manufacturing concrete for ultra-high strength reinforced concrete segments containing silica fume using a mixer that mixes raw materials, comprising: A mist spraying step is provided for spraying mist into the interior of the mixer. A method for producing concrete comprising the steps of:

2. A concrete manufacturing method for manufacturing concrete using a mixer that kneads raw materials, A mist spraying step is provided for spraying mist into the interior of the mixer. A method for producing concrete comprising the steps of:

3. The raw material includes silica fume 3. The method for producing concrete according to claim 2.

4. A mixed kneading water introduction step is provided in which liquid mixed kneading water is introduced into the mixer, The mist spraying step is started before the mixing and kneading water introducing step is started.

4. The method for producing concrete according to claim 1, wherein the concrete is mixed with the mixture.

5. the raw material contains water to be mixed into the concrete, the water mixture including a first water mixture used for the mist sprayed in the mist spraying step and a second water mixture used as liquid mixing water, a mixing / kneading water introducing step of introducing the second blending water into the mixer as a mixing / kneading water, In the mist spraying step, the first blended water is used to spray mist.

4. The method for producing concrete according to claim 1, wherein the concrete is mixed with the mixture.

6. The mist spraying step is started before the mixing and kneading water introducing step is started.

6. The method for producing concrete according to claim 5.

7. a silica fume introducing step of introducing the silica fume into the mixer; The mist spraying process is started after the silica fume introduction process is started.

4. The method for producing concrete according to claim 1 or 3.

8. A concrete manufacturing apparatus having a mixer for mixing raw materials, and for manufacturing concrete for ultra-high strength reinforced concrete segments containing silica fume, A mist spraying means is provided to spray mist into the inside of the mixer. A concrete manufacturing apparatus characterized by:

9. A concrete manufacturing apparatus for manufacturing concrete having a mixer for kneading raw materials, A mist spraying means is provided to spray mist into the inside of the mixer. A concrete manufacturing apparatus characterized by:

10. The raw material includes silica fume 10. The concrete manufacturing apparatus according to claim 9.

11. a mixed water introducing means for introducing liquid mixed water into the mixer, The mist spraying means sprays mist before the mixed kneading water introduction means introduces the liquid mixed kneading water.

11. The concrete manufacturing apparatus according to claim 8, wherein the concrete manufacturing apparatus is a concrete manufacturing apparatus having a plurality of suction holes.

12. the raw materials contain water to be mixed into the concrete, the water mixture including a first water mixture used for the mist sprayed by the mist spraying means and a second water mixture used as liquid mixing water, a mixed kneading water introducing means for introducing the second blending water into the mixer as a mixed kneading water, The mist spraying means sprays mist using the first blended water.

11. The concrete manufacturing apparatus according to claim 8, wherein the concrete manufacturing apparatus is a concrete manufacturing apparatus having a plurality of suction holes.

13. The mist spraying means starts spraying mist before the mixed-kneading water feeding means starts feeding the second blended water into the mixer as mixed-kneading water.

13. The concrete manufacturing apparatus according to claim 12.

14. a silica fume feeding means for feeding the silica fume into the mixer; The mist spraying means starts spraying mist after the silica fume feeding means feeds silica fume into the mixer.

11. The concrete manufacturing apparatus according to claim 8 or 10.

15. The mist spraying means has an opening and closing lid that can cover the spray nozzle.

11. The concrete manufacturing apparatus according to claim 8, wherein the concrete manufacturing apparatus is a concrete manufacturing apparatus having a plurality of suction holes.

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