JP7280012B2 - Deaerator for grout - Google Patents

Description

TECHNICAL FIELD The present invention relates to an air venting device for grout, and more specifically, to an air venting device for grout used for manufacturing mortar or paste grout used for buildings, civil engineering structures, and the like.

The normal compressive strength range of mortars and pastes used for buildings and civil engineering structures is 20 to 50 N/mm ² .
On the other hand, in some cases, ultra-high-strength grout with a compressive strength of about 80 to 400 N/mm ² is required. For example, it is used for the purpose of filling rebar joints at joints between precast members, which are high-strength concrete, and joints between members.
In order to increase the compressive strength of the mortar grout, the water-binder ratio must be low, for example below 20%.
However, when the water-binder ratio becomes small, the viscosity tends to increase and the fluidity tends to decrease. Fluidity is increased by using chemical admixtures, but when the compressive strength reaches a strength range exceeding 150 N/mm ² , it is necessary to reduce the water binder ratio to about 15% or less. , resulting in a more viscous grout.
A hand mixer can be used for kneading the grout material, but if the grout has a high viscosity, air bubbles will be formed due to outside air (entrained air) entrained in the grout. If there are many air bubbles, there is a concern that the compressive strength of the grout will be lowered. In addition, there is a concern that the air bubbles may coalesce after filling the joints and sleeves to form large voids.

The following techniques are known for reducing entrained air in grout.
(1) A vent pipe is attached to the upper part of the mixer case of the concrete mixer, and a concrete take-out pipe is attached to the lower part on the rotating shaft. A technique for venting more air (Patent Document 1).
(2) A container capable of storing a concrete-based mixed material, a hose for taking out the mixed material from the bottom of the container and placing it in an external formwork, a propeller installed inside the container, and the container Equipped with a pressurizing device and a decompressing device for pressurizing and depressurizing the inside of the container, the raw material pre-kneaded by the mixer is put into the container, and the inside of the container is decompressed by the decompressing device while the material is being stirred by the propeller. In addition, a technique for pressurizing the contents of a container with a pressurizing device when the mixed material is placed in the mold (see paragraph 0009 of Patent Document 2).
(3) A retention tank for retaining the grout, a vacuum pump for reducing the pressure in the retention tank to a vacuum state, an inlet for charging the material kneaded by the mixer into the retention tank, and retention Equipped with a rotating body for kneading the concrete material in the tank, a mesh-like barrier placed in the convection tank, and a discharge pump for discharging the grout in the retention tank, it is kneaded by a mixer in a vacuum state. A technique of applying a rotational centrifugal action by the rotating body to the material that has been crushed, expanding and destroying air bubbles in the grout by vacuum, and removing air (see claim 1, paragraphs 0012 to 0013, etc. of Patent Document 3).

Japanese Patent Laid-Open No. 53-19644 JP 2005-161724 JP 2014-240193

The technique of Patent Document 1 is for venting air during mixing, which is good for producing grout with normal compressive strength, but in order to produce grout with ultra-high strength, the degree of air venting is required. Inadequate.
In the techniques of Patent Documents 2 and 3, materials pre-kneaded by a mixer are rotated in a reduced pressure state or a vacuum state to degas, but special equipment such as a pressure reduction pump (including a vacuum pump) is required, and energy is required to operate it.

The applicant has made a serious study of this problem, and found that when the grout material is pressurized and transported through the pipe, the air bubbles caught in the process of kneading the grout gather on the pipe surface and exit from the discharge port. It was discovered that there is a phenomenon that the grout is released. This phenomenon is characterized in particular by the escape of air from the upper tube wall.
Although the reasons for these are not clear, it is thought that the characteristics of the flow of grout in the pipe and the phenomenon of air bubbles moving in the direction of lower pressure due to the driving force of the pressure gradient. That is, the grout forms a shear laminar flow accompanied by sliding with the pipe wall in the pipe, and flows so as to be pressed against the pipe wall side where the flow speed is slow from the center of the grout where the flow speed is high. It is thought that the air bubbles in the grout pressed against the pipe wall move to the discharge port while remaining near the pipe wall and sliding. In addition, since the air bubbles collected on the pipe wall in the circumferential direction in this way move to the upper side of the pipe cross section where the pressure is lower due to the influence of gravity, it is said that many air bubbles escaped from the upper part of the discharge port. Conceivable.
The present invention utilizes this phenomenon to apply pressure to the grout material, collect air bubbles on the low pressure side, and easily and efficiently remove larger air bubbles that have grown by coalescing a plurality of air bubbles. It is something to do.

A first object of the present invention is to provide an air venting device for grout that can reduce the amount of entrained air when kneading a grout material with a relatively small water-to-binder ratio and high viscosity with a simple configuration. That is.
A second object of the present invention is to provide an air venting device for grout that is more efficient in defoaming.

The first means includes a grout channel from the inlet to the outlet,
A pressurizing unit installed near the inlet of the grout channel and provided to pressure-feed the grout to the outlet side;
A bubble removing unit installed near the discharge port of the grout channel and configured to release air bubbles in the grout to the upper side of the channel and flow the grout from which the air bubbles have been removed to the discharge port side;
and
A channel portion between the pressurizing portion and the bubble removing portion is a closed channel,
The introduction path, which is the part of the closed flow path on the side of the defoaming section, is formed by a horizontal pipe section adjacent to the defoaming section, and fine bubbles of the grout fluid are gathered on the upper side of the horizontal pipe section. In a deaeration device for grout configured to have larger air bubbles,
The bubble removing portion is formed as a pressure removing portion where the fluid is exposed to the outside and the fluid pressure applied by the pressurizing portion is released.

In this means , as shown in FIG. 7, a pressurizing unit 12 is provided near the inlet of the grouting channel 2 extending from the inlet 4 to the introducing path 8, and a foam removing unit 14 is provided near the outlet. At least the part between the pressurizing part 12 and the defoaming part 14 in the flow path is a closed flow path, and the introduction path 8 of the fluid to the defoaming part 14 in this section is oriented laterally adjacent to the defoaming part 14. It is formed in the tube portion 8a.
The flow of grout containing fine air bubbles pressure-fed from the pressurizing part 12 into the closed channel becomes a shear flow with a high flow velocity on the center side and a low flow velocity near the pipe wall due to the action of the pressure. Air bubbles tend to be pushed outward from the center side.
Also, in the horizontal tube portion 8a, the air bubbles tend to rise due to the difference in density from the grout due to the action of gravity.
Due to these two actions, minute air bubbles in the grout gather in the upper side of the horizontal tube portion 8a and coalesce to grow into larger air bubbles. Therefore, on the tip end side of the horizontal pipe portion 8a, the flow in the pipe is divided into a flow mainly composed of foam and a flow mainly composed of grout. be. As a result, the grout from which the bubbles have been removed can be taken out.
Further, in this means, as shown in FIG. 7, the bubble removing section 14 is a depressurizing section in which the fluid is exposed to the outside and the fluid pressure applied by the pressurizing section is released. Since the fluid is exposed to the outside, air bubbles can be discharged more smoothly.
The illustrated depressurizing portion is composed of a free space through which the grout fluid discharged from the horizontal pipe portion in a pressure-releasing state passes, and a receiving portion 42 that receives the grout fluid passing through the free space. It does not have to be such a configuration. For example, the flow path downstream of the horizontal tube portion may be an open ditch type flow path with an open upper side instead of an underdrain type configuration such as a closed flow path.

The "foam removing part" may be of any mechanism as long as it can remove bubbles, but a suitable example is one that removes air bubbles due to the difference in density from the grout, and one that removes the fluid separated into the foam and the grout in a free space. Such as removal of air bubbles by exposure to pressure and release of pressure.
The term "upper side of the channel" includes both storing above the buffer container that constitutes the channel and releasing a part of the channel to the outside as a free space.
"Releasing the air bubbles in the grout to the upper side of the channel" means that there is an air reservoir part on the upper side of the channel, and the air bubbles may be released to the part, or released to the outside of the channel. You can.
In addition, "the grout from which air bubbles have been removed flows to the outlet side" means that the grout flows down due to the action of gravity from the outlet provided on the lower side of the defoaming unit, and that the grout flows down using pressure feeding means such as a pump. Including both pumping grout.
The “introduction path” is a portion of the channel portion between the pressurizing portion and the defoaming portion, which is located on the defoaming portion side and is for introducing the grout fluid to the defoaming portion. It is preferable to introduce the fluid into the defoaming section without disturbing the state of the flow separated into the fluid mainly composed of foam and the fluid mainly composed of grout in the horizontal tube portion.
The "horizontal tube portion" is not limited to a strictly horizontal one, and it is sufficient if the air bubbles b can be separated from the grout g by the gravitational action described above.

The second means has the first means and has a return flow path for circulation leading from a branch point formed downstream of the defoaming section to the upstream side of the pressurizing section,
A channel switching means is provided near the branch point ,
The foam removal section is provided in the grout channel portion between the pressurizing section and the branch point, or in the return channel for circulation, instead of the portion near the discharge port of the grout channel.

In this means, as shown in FIG. 9, the air is returned from the downstream branch point of the defoaming section 14 to the upstream confluence point of the pressurizing section 12 via the return flow path 50 . This allows the process of removing air bubbles to be repeated continuously. Further, flow path switching means is provided near the branch point.

According to the invention according to the first means, the part between the pressurizing part and the defoaming part of the grout channel is a closed channel, and the closed channel is connected to the defoaming part Since the introduction path, which is a continuous part, is formed by the horizontal pipe portion adjacent to the defoaming portion, the gravity acting on the horizontal pipe portion can be used to efficiently separate and remove entrained air in the grout. .
Further, according to the invention according to the first means, the defoaming portion is composed of a free space through which the grout fluid discharged from the laterally directed pipe portion passes, and a receiving portion that receives the grout fluid passing through the free space. , it is possible to effectively remove entrained air with a simple structure.
According to the invention according to the second means, there is provided a circulation return flow path extending from a branch point formed downstream of the defoaming section to the upstream side of the pressurizing section, and a flow path switching means is provided near the branch point . Therefore, the degassing effect can be improved by repeating the degassing process.

1 is an overall view of a grout air bleeding device according to a first embodiment of the present invention; FIG. 2 is a vertical cross-sectional view of the essential parts of the device of FIG. 1; FIG. FIG. 2 is a cross-sectional view of the essential parts of the device of FIG. 1; FIG. 2 is an operation explanatory view of the main part of the apparatus of FIG. 1; It is a figure which shows the modification of the principal part of FIG. 2, The figure (A) is a cross-sectional view of a principal part, The figure (B) is a longitudinal cross-sectional view of a principal part. It is a figure which shows the principal part of the deaeration apparatus for grouts which concerns on the 2nd reference example of this invention, the same figure (A) is a longitudinal cross-sectional view of a principal part, The same figure (B) is a part of the same figure (A). is an enlarged view of. 1 is an overall view of a grout air bleeding device according to a first embodiment of the present invention; FIG. Figure 8 is a longitudinal cross-sectional view of part of the device of Figure 7; FIG. 5 is an overall view of a grout air bleeding device according to a second embodiment of the present invention; 1 shows the effects of vibration and pressure, which are the results of Experimental Example 1 of the present invention. Fig. 10 shows the effect of pumping and curing methods resulting from the experiment of Fig. 10; The flow before and after pumping, which is the result of Experimental Example 2 of the present invention, is shown. Fig. 12 shows the amount of air in the grout before and after pumping, which is the result of the experiment in Fig. 12;

1 to 5 show a grout deaeration device 1 according to a first embodiment of the present invention.
This device includes a grouting channel 2 , a pressurizing section 12 and a defoaming section 14 .
The grouting channel 2 is continuous from the inlet 4 to the outlet 6 . A pressurizing unit 12 and a defoaming unit 14 are installed near the introduction port 4 of the grout channel 2 and the introduction channel 8 of the grout channel 2, respectively. In the illustrated example, an introduction port 4 is opened in the upper end surface of a tapered first hopper 10 for pouring grout. A pressure unit 12 is arranged directly below the first hopper 10 . Let the part between the pressurization part 12 and the bubble removal part 14 be the 1st flow path 2a among the flow paths 2 for grout, and let the part between the bubble removal part 14 and the discharge port 6 be the 2nd flow path 2b.
Among the grouting channels 2, at least the first channel 2a that is continuous with the pressurizing part 12 is formed as a closed channel so that the pressure applied by the pressurizing part 12 can reach the defoaming part 14. . The closed flow path can be formed, for example, as a hose or pipe. A portion of the first flow path 2 a on the defoaming section 14 side is an introduction path 8 for the grout fluid to the defoaming section 14 . In this reference example , the introduction path 8 is a linear flow path formed only by the lateral pipe portion 8a.

At least the lateral tube portion 8a of the first flow path 2a is formed of a laminar flow tube having a smooth inner surface. For example, it can be formed from a vinyl chloride pipe. Laminar flow tubes are suitable for conducting fluids in laminar flow. In this reference example , the entire first flow path 2a is formed of a laminar flow tube. The length L of the lateral tube portion 8a should be at least about 30 mm or more, preferably about 50 mm or more.

A cock 30 for opening and closing the flow path, and a second pump 32 for pumping fluid out of the grout air bleeding device are arranged in the second flow path 2b.

The pressurizing section 12 is configured as a fluid pump (first pump) for pressure-feeding the grout fluid to the defoaming section 14 side. The fluid pressure applied by the pressurizing part is preferably 0.05 MPa or higher. In the illustrated example, the fluid pump is held by a conventionally known stand S with the suction port facing upward, and the suction port is connected to the lower end of the first hopper 10 . However, these configurations can be changed as appropriate.
The defoaming section 14 is formed as a buffer container 16 in this reference example . As shown in FIG. 2, the illustrated buffer container consists of a main body having a cylindrical (cylindrical in the illustrated example) side wall 20 rising from the outer periphery of a bottom wall 18, and a lid portion 24 attached to the top of the main body. forming. An outer peripheral portion of a lid portion 24 is placed on a flange portion 22 attached to the upper end portion of the side wall, and a fixture F is inserted into a hole passing through the flange portion and the outer peripheral portion. However, this configuration can be changed as appropriate. An air hole 26 is formed in the central portion of the cover portion 24 in the illustrated example. However, the buffer container 16 may be a closed container.
The buffer container 16 has a certain height so that at least the upper portion of the internal volume can be used as an air reservoir.
At the bottom of the buffer container 16, a first connection port (inlet) I for connecting the first channel 2a and a second connection port (outlet) O for connecting to the second channel 2b are provided. It is The first connection port I and the second connection port O are preferably arranged apart from each other, for example, on opposite sides in the radial direction. In the preferred embodiment of FIG. 1, a first connection port I and a second connection port O are opened on diametrically opposite sides of the lower portion of the side wall 20 .
In the illustrated example, the first connection port I is provided in the vicinity of the bottom wall 18 (including the lower end of the side wall) as shown in FIG.
The second connection port O is also preferably provided in the vicinity of the bottom wall 18 (including the lower ends of the side walls). This is so that all the grout fluid in the buffer container 16 can be taken out.

In the above configuration, first, the outline of the method of using the device of this reference example will be described. With the cock 30 closed, grout that has already been kneaded by a concrete mixer or the like is put into the introduction port 4, and the pressure unit 12 is activated. Then, the grout is press-fitted from the pressurizing part 12 into the first channel 2a, which is a closed channel.
The grout fluid pressure-fed from the first flow path 2a enters the buffer container, which is the defoaming section 14, and accumulates in the buffer container. Discharge into a puddle. As shown in FIG. 4, when the liquid level of the grout fluid in the buffer container 16 exceeds the second connection port O, the cock 30 is opened and the second pump 32 is operated. If the second pump 32 is operated when the liquid level is lower than the second connection port O, the air in the buffer container 16 is sucked in through the second connection port O together with the grout fluid, causing air entrapment in the second pump. It is from. By operating the second pump 32, the grout fluid from which the air has been removed is taken out to the outside. This makes the mortar smoother and more fluid. Along with this, since the amount of air is reduced, the compressive strength after curing is increased, and an ultra-high strength grout can be produced.

At the stage of pressure-feeding the fluid from the pressurizing part 12 to the defoaming part 14, the flow in the first flow path becomes a shear laminar flow accompanied by slippage between the pipe walls in the pipe. The velocity distribution of the shear flow is such that the flow velocity is high at the center and decreases as it approaches the pipe wall. In this flow, the part on the center side where the flow velocity is high pushes the flow part on the outside where the flow velocity is low against the pipe wall side. As a result, minute bubbles contained in the grout fluid also tend to move toward the peripheral side (pipe wall side) in the fluid that undergoes repeated shear deformation.
When the grout fluid enters the lateral pipe portion 8a, which is the introduction passage 8 to the defoaming portion 14, the above-described tendency toward the peripheral side and the action of gravity combine to cause minute bubbles in the grout fluid to enter the lateral pipe portion 8a. At this point, microscopic bubbles coalesce with each other and gradually grow into large-diameter air bubbles. As a result, the flow in the pipe near the tip (the end on the defoamer side) of the horizontal pipe portion 8a is divided into a flow mainly composed of air bubbles and a flow of grout fluid containing less air.
Among the fluid that has entered the buffer container 16 in this manner, large-diameter air bubbles rise in the fluid and enter the air reservoir due to the difference in density from the surrounding grout. This allows the air bubbles and grout to be separated, reducing the air content of the remaining grout fluid.

FIG. 5 shows a modification of the defoamer 14 of this reference example . In this modified example, as shown in FIG. 5(a), the outer peripheral portion of a rectangular bottom wall 18 elongated in the direction of the grouting channel 2 or the rectangular tubular side wall 20 is erected. With this configuration, the form of the buffer container 16 can be made compact, and the degassing operation from the grout fluid can be efficiently performed.
In this modification, a first connection port I is provided in the lower part of the side wall corresponding to the short side of the rectangle.
A second connection port O is formed in a portion of the bottom wall 18 near the opposite short side of the rectangle, and a partition plate 28 is provided to divide the lower portion of the internal volume of the buffer container 16 into two in the longitudinal direction of the rectangle. are provided.
The lower end of the partition plate 28 is attached to the bottom wall 18 of the buffer container as shown in FIG. It is connected to both wall portions corresponding to sides. Also, the height of the partition plate 28 is smaller than the height of the side wall 20 .
The grout fluid entering the buffer container from the first connection port I accumulates in the space surrounded by the side wall 20 and the partition plate 28, air bubbles are released, and the liquid level rises to the height of the partition plate 28. 5B, it passes over the partition plate 28 and runs along the surface of the partition plate 28 and the upper surface of the bottom wall 18 as shown in FIG.
Other reference examples or embodiments of the present invention will be described below. In these explanations, explanations of the same structures as those of the first reference example are omitted.

FIG. 6 shows a grout deaerator 1 according to a second embodiment of the present invention. In this reference example , the form of the introduction path 8 of the grout fluid to the defoaming section 14 is changed.
The introduction path 8 of this reference example is an L-shaped flow path, and is formed of a horizontal pipe portion 8a and a vertical pipe portion 8b erected from the distal end side of the horizontal pipe portion 8a via an elbow E. .
In this configuration, large-diameter air bubbles b gather on the upper side of the lateral pipe portion 8a by the same action as in the first reference example , and the flow mainly composed of these air bubbles passes through the inside of the elbow E of the L-shaped flow path, and the rest of grout g flows through the outside of elbow E. At this time, since the outer flow pushes the inner flow upward and inward, the air bubbles are less likely to stay at the elbow E portion. The function of separating and removing air bubbles is not hindered.

7 and 8 show a grout air bleeding device 1 according to a first embodiment of the present invention. In this embodiment, the shape of the defoaming section 14 is mainly changed.
The defoaming section 14 of this embodiment is configured as a depressurizing section that releases the pressure applied in the pressurizing section 12 . For this reason, it is constructed such that all or part of the fluid that has entered the depressurization section from the first channel 2a, which is a closed channel, is exposed to the outside air.
In the illustrated example, the liquid is discharged into the free space 40 from the tip of the introduction channel 8, which is the sideways pipe portion 8a, and the discharged liquid is received by the receiving portion 42 and guided to the second flow channel 2b. The above-described free space 40 and the receiving portion 42 constitute the debubbling portion 14 of the illustrated example. Although the illustrated receiving portion 42 is formed of a tapered second hopper, it may have any shape as long as it can receive most of the grout fluid discharged from the introduction passage 8 into the free space 40 .
The illustrated device includes a second pump 32 for pumping the grout fluid that has entered the receiving portion 42 toward the second flow path 2b. The second pump 32 is held by a conventionally known stand S with the suction port facing upward, and the suction port is connected to the lower end of the second hopper, which is the receiving portion 42 .
In addition, the illustrated apparatus maintains a constant positional relationship with respect to the receiving portion 42 so that the receiving portion 42 can receive all of the grout fluid discharged from the lateral pipe portion 8a. It has a holder 44 that holds the . The illustrated holder 44 is configured such that a horizontal holding pipe 44b is provided at the end of an L-shaped support rod 44a extending from the receiving portion 42 side, and the horizontal pipe portion 8a can be inserted into the holding pipe 44b. ing.

According to the above configuration, the air bubbles collected on the upper inner surface of the tube wall of the horizontal tube portion 8a by the same action as in the first reference example are discharged into the free space 40 together with the grout fluid, and in this state, the pressure portion 12 As the applied pressure is released, it separates from the grout fluid and is released into the atmosphere. Then, only the grout fluid from which the air has been removed enters the receiving portion 42 and is discharged from the introduction passage 8 by the second pump 32 through the second flow passage 2b.

FIG. 9 shows a grout deaeration device 1 according to a first embodiment of the present invention. This device is provided with a return channel 50 for returning the fluid from the branch point Pd provided in the downstream channel portion of the pressurizing part 12 to the inlet 4, and the horizontal pipe part 8a is provided at the terminal end of the return channel 50. It is provided so as to circulate the fluid. The horizontal pipe portion 8a has the same structure as the horizontal pipe portion 8a of the first and second reference examples , and has the effect of collecting fine bubbles on the upper back side of the pipe wall and coalescing them into air bubbles of large particle size. have Therefore, the action of removing the air in the grout fluid can be repeated by circulating the fluid.
Compared with the apparatus of the second reference example , the first pump (pressurizing section 12) and the second pump 32 are used together, and the inlet 4 and the receiving section 42 are also used. In the illustrated example, the introduction port 4 on the upper side of the first hopper 10 also serves as the confluence point Pc of the return flow path 50 . Also, the space between the horizontal tube portion 8a and the first hopper 10 corresponds to the free space 40. As shown in FIG. Therefore, the free space and the first hopper 10 constitute the defoaming section 14 . However, this configuration can be changed as appropriate. For example, a buffer container may be provided in place of the defoaming section consisting of the free space and the first popper. Further, instead of the return flow path 50, the defoaming section 14 may be arranged in the flow path portion between the pressurizing section 12 and the branch point Pd.
A flow path switching means (not shown) is provided at a branch point Pd between the grouting flow path and the return flow path 50 to enable switching between a state in which the fluid is circulated in the device and a state in which the fluid is discharged from the device to the outside. there is

[Experimental example 1]
Tests (fresh test and compressive strength test results) performed in the mode of the first embodiment shown in FIGS. 7 and 8 will be described.
(1) Fresh test A fresh test was performed by kneading the grout material prior to pumping. As a specific procedure, the entire amount of water and admixture is put in a container, the premixed mortar powder is added in stages and mixed, and after all the premixed mortar is added, kneading is performed for 180 seconds. rice field. Table 1 shows the formulation of the grout material used. The silica fume cement in the table was previously added with silica fume so that the ratio of the mass (a) of silica fume to the total amount (x) of cement and silica fume was 10%. A mass (b) of coarse silica and a mass (c) of fine silica were added to this silica fume cement to obtain a binder of weight B (=x+b+c). The total amount of silica fume in the binder is represented by S (=a+b+c), and the ratio of the total amount of silica fume to the total amount of binder is represented by (100S/B).

Fresh test results are shown in Table 2. The grout flow was about 220mm. After kneading, there was a tendency that there was a lot of entrained air, so a vibrator (φ30 mm) was inserted to remove bubbles. After shaking with a vibrator, the air volume decreased slightly (0.6%), but the flow also decreased slightly.

After pumping, the amount of air decreased by 2-3% compared to before pumping, and the flow value increased slightly. The reason why the amount of air decreased greatly is not clear, but the phenomenon that air escapes from the mortar hopper during pumping was observed. The reason for the improvement in fluidity is thought to be that the cement particles are agitated by the shear flow of the cement particles under high pressure in the hose, resulting in an improved dispersion state of the particles. The mortar after pumping was clearly smoother than before pumping.

(2) Compressive strength test results Table 3 shows the compressive strength test and other cured physical properties, Fig. 10 shows the effects of vibration and pumping on compressive strength and air content, and Fig. 11 shows a comparison between before and after pumping and curing methods. . The density, compressive strength, and Young's modulus are the average values of the test results of three specimens.

It can be seen that the compressive strength increases as the amount of air decreases due to vibration and pumping. The effect of increasing the strength when pumped was large, and some batches increased by 50 N/mm ² or more with steam curing at 90°C. Since the joint is filled with the grout after pumping, it can be said that it is good to evaluate the strength of the grout after pumping, including quality control.
Compressive strength was 260-288N/mm ² when steam cured at 90°C, and 360N/mm ² when heat cured at 180°C after steam cured at 90°C. The former curing method sufficiently satisfies Fc250, and the latter curing method obtains compressive strength sufficiently satisfying Fc300. Since there is some margin in terms of strength, it was confirmed that it is possible to improve the fluidity by slightly increasing the amount of water within the range where the required strength can be obtained.

It becomes possible to efficiently produce a grout material with a high compressive strength of 100 to 500 N/mm ² class. Also, it is possible to suppress the occurrence of air pockets in the portion filled with the grout material. It is possible to further improve the quality of joints of precast members using ultra-high-strength concrete.

[Experimental example 2]
Furthermore, the results of tests conducted in the mode of the first embodiment , in which pumping was performed at least once or a plurality of times while changing the discharge rate of the pump, are shown.
Prior to pumping, a fresh test was performed using a binding material containing silica fume (SF). As a specific procedure, the entire amount of water and admixture is put in a container, the premixed mortar powder is added in stages and mixed, and after all the premixed mortar is added, kneading is performed for 180 seconds. rice field.
Table 4 shows the formulation of the materials used. SF is silica fume, and specifically coarse powder SF with a density of 2.20 g/cm ³ and fine powder SF with a density of 2.20 g/cm ³ were used. SFC is silica fume cement. Silica fume cement having a density of 3.08 g/cm ³ and silica sand having a density of 2.60 g/cm ³ were used as fine aggregate.
The blending amount of the superplasticizer is 5.0 parts by mass with respect to 100 parts by mass of the binder, and the blending amount of the antifoaming agent is 0.03 parts by mass with respect to 100 parts by mass of the binder.

The test items of the pumping test are flow, amount of air in grout, unit volume mass, temperature (environmental temperature AT and concrete temperature CT), grout discharge amount and grout discharge pressure.
In the first to fifth pumping tests, the W/B value is set to 10.5, and each item is measured in the first test without the pump operating, and in the second test, the discharge amount is substantially reduced. In the third run, the discharge rate is set to 50, in the fourth run, the discharge rate is set to 100, in the fifth run, the discharge rate is set to 100, and the pump is pumped five times using the circulation path shown in FIG. Each item was measured repeatedly under different conditions. It should be noted that the discharge amounts 50 and 100 represent mutual relative numerical values of the discharge amounts (volumes).
Furthermore, in the 6th to 8th pumping tests, the W/B value was set to 11, and in the 6th test, each item was measured while the pump was not operating. Each item was measured by setting the ejection amount to 0 and setting the discharge amount to 50 in the eighth time.
Except for the 1st and 6th times, the flow, the air amount in the grout, the unit volume mass, the temperature (CT and AT) were measured before and after pumping, and the grout discharge rate and grout discharge pressure were measured. was measured during pumping.
The results of the tests are shown in Table 5 below.

From the experimental results in Table 5, it can be seen that the amount of air after pumping was lower than before pumping for all of the 2nd to 5th and 7th to 8th runs. In other words, there is a defoaming effect regardless of the amount of pump discharge.
Also, in the 5th time in which the pumping process was repeated 5 times, the rate of decrease in the air amount was remarkable compared to the 2nd to 4th times and the 5th to 6th times in which the pumping process was performed only once. That is, it can be seen that the defoaming action is improved by repeating the pumping process.
The above results are illustrated in FIG.
Also, from the numerical values of the flow in Table 5, it can be seen that the flow increases by about 10 mm before and after pumping by the pump, and that the flow value is large when refluxing from downstream to upstream of the pump. The results are illustrated in FIG.

The above explanations merely describe preferred embodiments or reference examples of the present invention, and it goes without saying that the present invention can be embodied in various forms without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1... Grout air bleeding device 2... Grout flow path 2a... 1st flow path 2b... 2nd flow path 4... Inlet 6... Discharge port 8... Introductory path 8a... Horizontal pipe portion 8b... Vertical pipe portion 10... DESCRIPTION OF SYMBOLS 1st hopper 12... Pressurization part (1st pump) 14... Defoaming part 16... Buffer container 18... Bottom wall 20... Side wall 22... Collar part 24... Lid part 26... Air hole 28... Partition plate 30... Cock 32... Second pump 40 Free space 42 Receiving part (second hopper)
44... Holding tool 44a... Supporting rod 44b... Holding pipe 50... Return channel b... Air bubble E... Elbow F... Fixing tool g... Grout I... First connection port O... Second connection port Pc... Junction point Pd... Branch Point S…Stand

Claims (2)

a grout channel from the inlet to the outlet;
A pressurizing unit installed near the inlet of the grout channel and provided to pressure-feed the grout to the outlet side;
A bubble removing unit installed near the discharge port of the grout channel and configured to release air bubbles in the grout to the upper side of the channel and flow the grout from which the air bubbles have been removed to the discharge port side;
and
A channel portion between the pressurizing portion and the bubble removing portion is a closed channel,
The introduction path, which is the part of the closed flow path on the side of the defoaming section, is formed by a horizontal pipe section adjacent to the defoaming section, and fine bubbles of the grout fluid are gathered on the upper side of the horizontal pipe section. In a deaeration device for grout configured to have larger air bubbles,
The deaeration device for grout, wherein the debubbling portion is formed as a depressurizing portion that exposes the fluid to the outside and releases the fluid pressure applied by the pressurizing portion. Having a return flow path for circulation leading from a branch point formed downstream of the defoaming section to the upstream side of the pressurizing section,
A channel switching means is provided near the branch point ,
The debubbling part is provided in a grout channel part between the pressurizing part and the branch point, or in a return channel for circulation, instead of a part near the discharge port of the grout channel. 2. A deaeration device for grout according to claim 1 .

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