JP2020163657A - Dry spray method and injection machine - Google Patents

Abstract

To provide a dry spray method capable of suppressing rebound generated upon spray to an object.SOLUTION: A dry spray method has a process where, using an injection machine injecting a spray material formed by mixing a cement-containing powder material and a water-containing liquid material together with a gas, the spray material is sprayed on an object. The injection machine is provided with a hose part forming a flow passage through which the spray material is circulated together with the gas, the hose part is provided with an injection port injecting the spray material from the flow passage of the spray material, and is composed so as to be freely curbed into an arc shape. The method comprises a step where the spray material is injected from the injection port in a state in which the hose part is curved into an arc shape, and a curbed part is formed at the hose part, and the spray material is sprayed on the object.SELECTED DRAWING: Figure 2

Description

The present invention relates to a dry spraying method in which a spraying material containing cement and water is sprayed onto an object. The present invention also relates to an injector that can be used in the dry spraying method.

Conventionally, a method of applying a spraying material on the surface of an object by spraying a spraying material containing cement and water onto the object has been known. For example, in construction work such as excavated tunnels and underground spaces, the excavated surface is prevented from collapsing by spraying a cement composition (specifically, concrete) having quick hardness on the excavated surface as a spraying material. ..

As a method of spraying the spray material onto the object, a method of injecting the spray material together with the gas from the spray nozzle is generally known. Specifically, the powder material containing cement and the liquid material containing water are separately supplied to the spray nozzle. Then, a method (so-called dry spraying method) in which a powder material and a liquid material are mixed in the spraying nozzle to form a spraying material, and the spraying material is sprayed together with a gas to spray the object. ) Is known (see Patent Document 1).

By the way, as described above, when the spray material is sprayed from the spray nozzle to the object, a part of the spray material rebounds from the object and scatters around the object. It causes deterioration. As a method of suppressing the rebound of the spray material, it is conceivable to spray the spray material from an appropriate distance to the object.

Japanese Unexamined Patent Publication No. 2001-012867

However, depending on the environment in which the spraying work is performed, it may not be possible to secure a sufficient distance from the object to the spraying nozzle. In such a case, since it is necessary to inject the spray material from a position relatively close to the object, it becomes difficult to suppress the rebound of the spray material.

Therefore, an object of the present invention is to provide a dry spraying method capable of suppressing rebound that occurs when spraying onto an object. Another object of the present invention is to provide an injector that can be used in the dry spraying method.

The dry spraying method according to the present invention targets the spraying material by using an injector that injects a spraying material formed by mixing a powder material containing cement and a liquid material containing water together with a gas. It is a dry spraying method that sprays on an object, and the injector is provided with a hose portion that forms a flow path through which the spray material flows together with the gas, and the hose portion is a spray material from the flow path of the spray material. It is provided with an injection port for injecting gas, and is configured to be freely curved in an arc shape. In a state where the hose portion is curved in an arc shape to form a curved portion in the hose portion, the spray material is injected from the injection port. A step of spraying a spray material on an object is provided.

According to such a configuration, the hose portion is curved in an arc shape to form a curved portion in the hose portion. As a result, the flow path of the spray material in the hose portion is in a curved state at the curved portion. Then, with the curved portion formed, the spraying material is sprayed from the injection port to spray the spraying material onto the object. As a result, the spray material flowing through the hose portion is decelerated at the curved portion and then injected from the injection port. Therefore, the injection speed of the spray material at the injection port is slower than when the curved portion is not formed in the hose portion. As a result, the impact when the spray material collides with the object is reduced, so that a sufficient distance between the object to which the spray material is sprayed and the injection port cannot be secured (the object and the injection port). Even when the distance between them is relatively short), the rebound of the spray material can be suppressed.

The radius of the arc on the outside of the curved portion is preferably 150 mm or more and 400 mm or less.

According to such a configuration, when the radius of the arc outside the curved portion is in the above range, the spraying material flowing in the hose portion can be more reliably decelerated. Therefore, the rebound of the spray material can be suppressed more reliably.

It is preferable to include a step of adjusting the radius of the arc outside the curved portion according to the distance between the object and the injection port.

According to such a configuration, the injection speed of the spray material at the injection port 1a can be controlled by adjusting the radius of the arc outside the curved portion. As a result, the injection speed of the spray material can be adjusted according to the distance between the object and the injection port, so that the rebound of the spray material can be suppressed more reliably.

The injector is provided with a powder-liquid contact portion that contacts the powder material and the liquid material, and the length of the flow path of the spray material from the powder-liquid contact portion to the injection port is 50 cm or more and 250 cm or less. It is preferable to have.

According to such a configuration, when the length of the flow path of the spray material from the powder liquid contact portion to the injection port is within the above range, the spray material can be satisfactorily kneaded in the hose portion. ..

The diameter of the flow path of the spray material in the hose portion is preferably 20 mm or more and 75 mm or less.

According to such a configuration, when the diameter of the flow path of the spray material in the hose portion is within the above range, the spray material can be satisfactorily kneaded in the hose portion.

The injector according to the present invention is an injector that injects a spray material formed by mixing a powder material containing cement and a liquid material containing water together with a gas in order to spray the spray material onto an object. The hose portion is provided with a hose portion that forms a flow path through which the spray material flows together with the gas, and the hose portion is provided with an injection port for injecting the spray material from the flow path of the spray material and is curved in an arc shape. It is freely configured, and in a state where the hose portion is curved in an arc shape to form a curved portion in the hose portion, the spray material can be sprayed from the injection port to spray the spray material on the object. To.

According to such a configuration, the hose portion is curved in an arc shape to form a curved portion in the hose portion. As a result, the flow path of the spray material in the hose portion is in a curved state at the curved portion. Then, with the curved portion formed, the spraying material is sprayed from the injection port to spray the spraying material onto the object. As a result, the spray material flowing through the hose portion is decelerated at the curved portion and then injected from the injection port. Therefore, the injection speed of the spray material at the injection port is slower than when the curved portion is not formed in the hose portion. As a result, the impact when the spray material collides with the object is reduced, so that a sufficient distance between the object to which the spray material is sprayed and the injection port cannot be secured (the object and the injection port). Even when the distance between them is relatively short), the rebound of the spray material can be suppressed.

As described above, according to the present invention, it is possible to suppress the rebound that occurs when the object is sprayed.

A partial cross-sectional view showing an outline of an injector used in the dry spraying method according to an embodiment of the present invention. The figure which showed the outline of the dry spraying method which concerns on the same embodiment. The figure which showed the outline of the dry spraying method which concerns on other embodiments. The figure which showed the 90 ° bending radius in an Example.

Hereinafter, embodiments of the present invention will be described.

In the dry spraying method according to the present invention, a powder material containing cement and a liquid material containing water are mixed to form a spraying material, and the spraying material is sprayed together with a gas onto an object.

The cement contained in the powder material is not particularly limited, and various cements available on the market can be used. Specifically, various Portland cements such as ordinary Portland cement and early-strength Portland cement, various mixed cements with blast furnace cement, silica cement and fly ash cement, white Portland cement, alumina cement, calcium aluminate-based, and calcium. One selected from the group consisting of ultrafast hard cement such as sulfoaminete type and calcium fluoroaluminate type may be used, or a plurality of cements may be mixed and used.

The powder material may include an aggregate.

As the aggregate, coarse aggregate and fine aggregate may be used, or only fine aggregate may be used. That is, when coarse aggregate and fine aggregate are used as the aggregate, the spraying material constitutes concrete, and when only fine aggregate is used as the aggregate, the spraying material is It constitutes a mortar.

As the coarse aggregate, a material having a size of 85% by mass or more that does not pass through a 5 mm sieve can be used. Specifically, as coarse aggregate, sandstone crushed stone, ball gravel (river gravel), natural lightweight coarse aggregate (perlite, hill stone, etc.), by-product lightweight coarse aggregate, artificial lightweight coarse aggregate, recycled aggregate, etc. Can be mentioned. The content of the coarse aggregate is not particularly limited, and may be, for example, 180% by mass or more and 210% by mass or less, or 190% by mass or more and 200% by mass or less with respect to cement. ..

As the fine aggregate, a material having a size of 85% by mass or more that passes through all the sieves of 10 mm and passes through the sieves of 5 mm can be used. Specifically, as fine aggregate, natural sand such as mountain sand, river sand, land sand, and sea sand, and crushed sand formed by artificially crushing sandstone, limestone, etc. (more specifically, lime). Crushed sand, etc.). The content of the fine aggregate is not particularly limited, and may be, for example, 100% by mass or more and 300% by mass or less, or 150% by mass or more and 250% by mass or less with respect to cement. ..

The sizes of the coarse aggregate and the fine aggregate are measured by the aggregate sieving test method according to JIS A 1102, and represent the test sieve of JIS Z 8801-1.

Further, the powder material may include a material other than cement. For example, powder materials include fiber materials (glass fiber, steel fiber, vinylon fiber, aramid fiber, polypropylene fiber, carbon fiber, etc.), admixture (blast furnace slag, fly ash, silica fume, expansion material, etc.), admixture (water reduction). Agents, thickeners, antifoaming agents, etc.) may be included.

The water contained in the liquid material is not particularly limited, and general tap water can be used. Moreover, the liquid material may include a material other than water. For example, the liquid material may contain an admixture such as a water reducing agent used when kneading mortar or concrete, a polymer dispersion liquid, a shrinkage reducing agent, a coagulation adjusting agent and the like.

Further, at least one of the powder material and the liquid material may contain various quick-setting agents exemplified in the background art.

In the dry spraying method according to the present invention, an injector that injects the spraying material as described above toward an object (for example, a wall surface formed by excavation) together with gas is used. Specifically, as shown in FIG. 1, the injector 10 has a hose portion 1 that forms a flow path F through which the spray material flows together with the gas, and a powder-liquid contact portion that contacts the powder material and the liquid material. 2, a powder transporting unit 3 for transporting the powder material together with the gas, and a liquid transporting unit 4 for transporting the liquid material are provided.

The powder transport portion 3 is formed by using a tubular member. Then, the powder transport unit 3 is connected to the powder liquid contact unit 2 and supplies the powder material together with the gas to the powder liquid contact unit 2. The diameter 3R inside the powder transport portion 3 is not particularly limited, and is, for example, preferably 20 mm or more and 75 mm, and more preferably 25 mm or more and 50 mm or less. The liquid transport portion 4 is formed by using a tubular member. Then, the liquid transport unit 4 is connected to the powder liquid contact unit 2 to supply the liquid material to the powder liquid contact unit 2. The powder-liquid contact portion 2 forms a spraying material by contacting and mixing the powder material supplied from the powder transport unit 3 and the liquid material supplied from the liquid transport unit 4. Then, the powder-liquid contact portion 2 supplies the formed spray material to the flow path F of the hose portion 1.

The hose portion 1 is provided with an injection port 1a at one end for injecting the spray material formed by the powder liquid contact portion 2 together with the gas, and the other end is connected to the powder liquid contact portion 2. The length L1 of the flow path F of the spray material from the powder liquid contact portion 2 to the injection port 1a (that is, the distance at which the spray material is kneaded) is not particularly limited, and is, for example, 50 cm. It is preferably 250 cm or more, and more preferably 100 cm or more and 225 cm or less. The inner diameter (diameter of the flow path F) R1 of the hose portion 1 is not particularly limited, and is preferably, for example, 20 mm or more and 75 mm, and more preferably 25 mm or more and 50 mm or less. The inner diameter (diameter of the flow path F) R1 of the hose portion 1 is preferably 0.66 or more and 1.36 or less, preferably 0.66 or more, with respect to the inner diameter 3R of the powder transport portion 3. It is preferably 1.23 or less.

The hose portion 1 is configured to be deformable (curvable) so that the flow path F of the spraying material is curved. In the present embodiment, the tubular member constituting the hose portion 1 is formed in a bellows shape.

Next, a method of spraying the spraying material onto the object (dry spraying method) using the injector 10 as described above will be described.

As shown in FIG. 2, when the spray material is sprayed on the object X, the hose portion 1 is deformed so that the flow path F of the hose portion 1 is curved to form an arc-shaped curved portion 1b. The angle of the curved portion 1b is not particularly limited, and is preferably, for example, 45 ° or more and 135 ° or less, and more preferably about 90 °. The position where the curved portion 1b is formed is not particularly limited, and for example, the distance L2 from the injection port 1a (distance between the injection port 1a and the curved portion 1b) L2 is 10 cm or more and 30 cm or less. It is preferably 10 cm or more and 20 cm or less, more preferably. The length L3 of the curved portion 1b is not particularly limited, and is preferably 40 cm or more and 240 cm or less, and more preferably 100 cm or more and 240 cm or less. The radius R3 of the arc on the outer side of the curved portion 1b is not particularly limited, and is preferably 150 mm or more and 400 mm or less, and more preferably 150 mm or more and 300 mm or less. Further, the radius R3 of the arc outside the curved portion 1b is preferably adjusted according to the distance L4 between the object X and the injection port 1a.

The distance L4 between the object X and the injection port 1a is not particularly limited, and is preferably, for example, 30 cm or more and 120 cm or less, and more preferably 30 cm or more and 100 cm or less. Then, as described above, with the curved portion 1b formed in the hose portion 1, the spraying material is sprayed from the injection port 1a, and the spraying material is sprayed onto the object X.

As described above, according to the dry spraying method and the injector according to the present invention, it is possible to suppress the rebound that occurs when spraying the object.

That is, the hose portion 1 is curved in an arc shape to form the curved portion 1b in the hose portion 1. As a result, the flow path F of the spraying material in the hose portion 1 is in a curved state at the curved portion 1b. Then, with the curved portion 1b formed, the spraying material is injected from the injection port 1a to spray the spraying material onto the object X. As a result, the spray material flowing through the hose portion 1 is decelerated at the curved portion 1b and then injected from the injection port 1a. Therefore, the injection speed of the spray material at the injection port 1a is slower than when the curved portion 1b is not formed in the hose portion 1. As a result, the impact when the spray material collides with the object X is reduced, so that a sufficient distance between the object X to which the spray material is sprayed and the injection port 1a cannot be secured (object X). Even when the distance between the injection port 1a and the injection port 1a is relatively short), the rebound of the spray material can be suppressed.

Further, when the radius R3 of the arc outside the curved portion 1b is within the above range, the spraying material flowing in the hose portion 1 can be more reliably decelerated. Therefore, the rebound of the spray material can be suppressed more reliably.

Further, by adjusting the radius R3 of the arc outside the curved portion 1b, the injection speed of the spray material at the injection port 1a can be controlled. As a result, the injection speed of the spray material can be adjusted according to the distance between the object X and the injection port 1a, so that the rebound of the spray material can be suppressed more reliably.

Further, when the length of the flow path F of the spraying material from the powder liquid contact portion 2 to the injection port 1a is within the above range, the spraying material can be satisfactorily kneaded in the hose portion 1. ..

Further, when the diameter R1 of the flow path F of the spray material in the hose portion 1 is within the above range, the spray material can be satisfactorily kneaded in the hose portion 1.

The dry spraying method and the injector according to the present invention are not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. Further, the configurations and methods of the plurality of embodiments described above may be arbitrarily adopted and combined (the configuration and methods of one embodiment may be applied to the configurations and methods of other embodiments). Of course, it is also possible to arbitrarily select a configuration or method according to various other modified examples and adopt the configuration or method according to the above-described embodiment.

For example, in the above embodiment, the hose portion 1 is configured to have one curved portion 1b, but the present invention is not limited to this, and for example, as shown in FIG. 3, the hose portion 1 is formed. A plurality (specifically, two) of curved portions 1b may be formed. With this configuration, the spray material is decelerated at a plurality of locations (specifically, two locations) of the hose portion 1, so that the injection speed of the spray material at the injection port 1a is more reliable. Can be reduced to. As a result, the rebound of the spray material can be suppressed more reliably.

Further, in the above embodiment, the hose portion 1 is composed of a bellows-shaped tubular member, but the present invention is not limited to this, and for example, a conventional spraying nozzle is attached to the tip of the bellows-shaped tubular member. May be connected to form the hose portion 1. In such a case, the injection port 1a is provided in the spray nozzle. Alternatively, the hose portion 1 may be connected to the tip end portion of the conventional spraying nozzle.

Further, in the above embodiment, the hose portion 1 is composed of a bellows-shaped tubular member, but is not particularly limited as long as it can be deformed to such an extent that the curved portion 1b can be formed. For example, the hose portion 1 may be configured by using a tubular member that is not bellows-shaped.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

<Materials used (product name, company name, etc.)>
A: Powder component / cement: Ordinary Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd.)
・ Fine aggregate: Silica sand No. 1, No. 2, No. 7 B: Liquid component ・ Water: Tap water ・ Liquid admixture: Lion Bond A (manufactured by Sumitomo Osaka Cement Co., Ltd.)

<Mixing of powder material and liquid material>
Using a Towa rotary gun sprayer, the mixture of each of the above powder components was pneumatically fed at the ratio shown in Table 1 below. The pumping distance was 60 m in the horizontal direction.
Further, the mixture of each liquid component was pumped at the ratio shown in Table 1 below. The pumping distance was 60 m in the horizontal direction.

<Injection conditions for spray material>
The powder pumping pressure of the Towa rotary gun was set to 0.10 MPa. The pressure at the tip of the cylinder in this case is about 0.05 MPa.

1. 1. Test 1
<Rebound rate>
The bounce rate was measured in accordance with JSCE-F 563. The mass of the mold having an internal space of 35 cm × 45 cm × 30 cm (hereinafter, also referred to as the initial mold mass) was measured as the object to be sprayed.
Then, a sheet material was laid around the mold, and the spray material was sprayed onto the mold in the state shown in FIG. 2 using the injector 10 shown in FIG. 1 (spraying step).
Then, the mass of the mold after the spraying step (hereinafter, also referred to as the mass of the mold after spraying) was measured.
The distance L4 from the mold (object) to the injection port 1a was set to 30 cm.
The conditions for the spraying process are shown in Table 2 below. As shown in FIG. 4, the “90 ° bending radius” is the radius R3 of the arc outside the curved portion 1b formed when the hose portion 1 is bent 90 °.

The rebound rate was calculated using the obtained measurement results, the mass (rebound amount) of the sprayed material on the sheet material, and the following equation (1). The calculated bounce rate is shown in Table 2 below.
The "construction amount" in the following equation (1) is the difference between the formwork mass after spraying and the initial formwork mass.

・ Bounce rate = Bounce amount ÷ (Construction amount + Bounce amount) x 100 ... (1)

<Discharge amount>
Using the injector 10 shown in FIG. 1, the mass of the sprayed material in the flexible container bag when the sprayed material was injected into the flexible container bag for 1 minute in the state shown in FIG. 2 was defined as the discharge amount. The discharge amount is shown in Table 2 below.

<Compression strength>
After the spray material sprayed on the mold was cured in the spraying step, a core having a diameter of 10 cm × 20 cm was sampled, cured in water at 20 ° C., and then the compression strength at the age of 28 days was measured. The compression strength was measured based on JIS A1108 “Concrete Compression Strength Test Method”. The measurement results of the compression strength are shown in Table 2 below.

<Fillability test on the back of the reinforcing bar>
A mold conforming to JHS432 "Test method for spray mortar for cross-section repair" is installed on the wall surface, and the spray material is sprayed onto the mold in the state shown in FIG. 2 using the injector 10 shown in FIG. Attached (spraying process). The conditions of the spraying process are shown in Table 2 below.
Then, after the spray material was cured, the spray material was cut together with the mold at a predetermined position, the filling state in the vicinity of the reinforcing bar on the cut surface was visually confirmed, and the length of the void was measured. The measurement results of the gap length are shown in Table 2.

2. Test 2
The same test as in Test 1 was performed except that the 90 ° bending radius was set to 200 mm and L1 (kneading distance) in FIG. 1 was changed. The test results are shown in Table 3 below.

3. 3. Test 3
Except that the 90 ° bending radius is set to 200 mm and the inner diameter (inner diameter) 3R of the tubular member constituting the powder transport portion 3 and the inner diameter (inner diameter) R1 of the tubular member constituting the hose portion 1 are changed. Performed the same test as in Test 1. The test results are shown in Table 4 below.

4. Summary Looking at Table 2, it can be seen that the rebound rate changes by changing the 90 ° bend radius. That is, it is recognized that the radius R3 of the arc outside the curved portion 1b affects the rebound rate. Therefore, by injecting the spraying material from the injection port 1a and performing the spraying step in the state where the curved portion 1b is formed in the hose portion 1, the rebound of the spraying material can be suppressed. Further, comparing Test Examples 1 to 3 with Test Examples 4 and 5, it is recognized that Test Examples 1 to 3 have a lower rebound rate. That is, by forming the curved portion 1b so that the 90 ° bending radius is 150 mm or more and 300 mm or less, the rebound of the sprayed material can be suppressed more reliably.

Comparing Test Examples 8 to 11 in Table 3 with Test Examples 6, 7 and 12, it is found that Test Examples 8 to 11 have a lower rebound rate. That is, when the kneading distance (L1 in FIG. 1) is 50 cm or more and 250 cm or less, the rebound of the sprayed material can be suppressed more reliably.

Comparing Test Examples 13 to 15 in Table 4 with Test Example 16, it is confirmed that Test Examples 13 to 15 have a lower rebound rate. That is, when the ratio (R1 / 3R) of the inner diameter R1 of the hose portion 1 to the inner diameter 3R of the powder transport portion 3 is 0.7 or more and 1.4 or less, the rebound of the spray material can be suppressed more reliably. Can be done.

Further, by providing the curved portion 1b, it is possible to adjust the discharge pressure and the discharge amount corresponding to the distance L4 from the sprayed object X, so that the sprayed material is less likely to have voids, and the table shows. As can be seen from the results of the compression strengths of 2 to 4, good compression strength can be obtained.

Further, as can be seen from the results of the rebar back filling property in Tables 2 to 4, the angle of the injection port 1a with respect to the spraying object X can be freely changed, so that the rebar back and the like are well filled with the spray material. Can be done.

1 ... hose part, 1a ... injection port, 1b ... curved part, 2 ... powder liquid contact part, 3 ... powder transfer part, 3R ... diameter of powder transfer part, 4 ... liquid transfer part, 10 ... injector, R3 ... radius of curved part, F ... flow path of spray material, X ... object

Claims (6)

It is a dry spraying method in which a spraying material formed by mixing a powder material containing cement and a liquid material containing water is sprayed onto an object by using an injector that injects the spraying material together with gas. ,
The injector is equipped with a hose section that forms a flow path through which the spray material flows with the gas.
The hose portion is provided with an injection port for injecting the spray material from the flow path of the spray material, and is configured to be bendable in an arc shape.
A dry spraying method including a step of injecting a spray material from an injection port to spray a spray material onto an object in a state where the hose portion is curved in an arc shape to form a curved portion in the hose portion. The dry spraying method according to claim 1, wherein the radius of the arc on the outside of the curved portion is 150 mm or more and 400 mm or less. The dry spraying method according to claim 1 or 2, further comprising a step of adjusting the radius of the arc outside the curved portion according to the distance between the object and the injection port. The injector is provided with a powder-liquid contact portion that brings the powder material into contact with the liquid material.
The dry spraying method according to any one of claims 1 to 3, wherein the length of the flow path of the spraying material from the powder contact portion to the injection port is 50 cm or more and 250 cm or less. The dry spraying method according to any one of claims 1 to 4, wherein the diameter of the flow path of the spraying material in the hose portion is 20 mm or more and 75 mm or less. An injector that injects a spray material formed by mixing a powder material containing cement and a liquid material containing water together with a gas in order to spray the spray material onto an object.
It is equipped with a hose part that forms a flow path through which the spray material flows with the gas.
The hose portion is provided with an injection port for injecting the spray material from the flow path of the spray material, and is configured to be bendable in an arc shape.
An injector configured to inject a spray material from an injection port to spray a spray material onto an object in a state where the hose portion is curved in an arc shape to form a curved portion in the hose portion.