JP2000282036A - Plastic injection material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject injection material rapidly being plasticized, not separating in water and equipped with a desired specific gravity by agitating and mixing a cement (air) milk with a bentonite milk and a particle material for adjusting specific gravity. SOLUTION: This objective injection material is obtained by agitating and mixing (A) a cement milk or a cement air milk obtained by mixing air bubbles with the cement milk, with (B) a bentonite milk and (C) a particle material for adjusting specific gravity. As the component C, foamed beads are preferable in the case of making the material lighter weight than that of the plastic injection material obtained by kneading the components A and B, and sand and/or conglomerates are preferable in the case of making it heavier. The injection material is preferably formed by the component A having (1:0.3)-(1:1) formulation ratio by weight of a cement to water with the component B having (1:4)-(1:12) weight blending ratio of a bentonite to water. Also, it is preferable to have >=15 swelling capacity of the bentonite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition of a plastic injection material that can be used for filling a cavity of a civil engineering structure, lightweight embankment, landfill, and the like.

[0002]

2. Description of the Related Art When an injection material is used for filling a cavity of a civil engineering structure or the like, and there is groundwater or running water in the cavity filling portion, the injection material is prevented from being diluted with the groundwater or the running water. Injectable materials may be required to have properties as a gel-like aggregate. In addition, in the case where the filling portion is limitedly injected in sections, there is a problem that a normal cement milk-based injection material causes a problem of departure to the surroundings and limited injection cannot be performed.
In this way, the injection material is in a state of an aggregate that has gelled,
The following describes that without being diluted into groundwater or running water, the shape imparting property makes it difficult for deviation to the surroundings to occur.
It will be referred to as "plasticity".

[0003] For such reasons, conventionally, in the injection of cement milk, cement air milk, or the like, a technique of adding plasticity to an injection material by adding a water glass-based chemical solution or aluminum salts to cement milk, cement air milk, or the like has been used. Have been.

Conventionally, a cement-bentonite suspension has been known as an injecting material. This cement-bentonite suspension has an effect of increasing viscosity, but cannot be made into a plastic state. Not practically used for injection. As a preparation procedure of the cement / bentonite suspension, montmorillonite, which is a main component of bentonite, easily undergoes an exchange reaction with calcium ions in the cement and does not swell. A method has been practiced in which bentonite milk mixed with water is prepared, and after the bentonite has sufficiently swelled, cement powder is added to prepare it.

On the other hand, it is known to use magnesium chloride, calcium chloride, aluminum sulfate and the like as a flocculant for bentonite. Also, when cement concrete is accidentally mixed into bentonite mud,
It is known that bentonite aggregates and separates due to cement concrete and causes breathing. However, there is no technical idea of plasticizing bentonite milk with cement milk by utilizing the agglomeration phenomenon of bentonite and utilizing this as a plastic injection material.

[0006] Japanese Patent Publication No. 55-35533 discloses a filling material to be filled in a trench for impermeable wall construction.
It is described that a resilient impermeable wall is constructed by using a mixture of cement milk or mortar and a slurry obtained by mixing bentonite mud and slime evenly. However, the technology described in this publication is
This is a technology for use as a cement / bentonite composite cured product, and does not actively plasticize cement-based fillers due to the cohesiveness of bentonite.

[0007]

It is known that the above-mentioned water glass-based chemical liquid material causes a leaching phenomenon in which unreacted sodium ions of water glass are eluted by water such as groundwater or running water. In addition to problems, groundwater may be contaminated by high alkali, and it is necessary to take sufficient measures to prevent pollution.

Further, since the aluminum salt material is expensive, the injection material is expensive and the cost is increased, and it is known that leaching phenomenon occurs in which unreacted anions are eluted, and there is a problem in durability. In addition, groundwater may be polluted by anions, and it is necessary to take sufficient measures to prevent pollution. Although the cement-bentonite suspension is known to have an effect of increasing viscosity, it has a problem that it cannot be plasticized instantaneously.

[0009] Therefore, the applicant of the present invention has found that when bentonite milk is mixed with cement milk, strong agglomerates can be formed by the action of the agglomeration of bentonite by the calcium ions, and the injection material in a plastic state with a controlled flow value. It has been found that the above problem can be solved by injecting this mixture as an injection material, and a patent application has been filed as Japanese Patent Application No. 10-130143.

However, it is desirable that the specific gravity of the injected material is small when backfilling is performed for tunnel repair or improvement work, while the specific gravity of the injected material is required when filling the water such as groundwater. A larger value is preferable because it can prevent a situation of floating on water. That is, it is desired to use an injection material having a predetermined specific gravity depending on the location where the injection material is injected.

Here, in the above-mentioned application, it is proposed to mix air bubbles into the injection material in order to reduce the specific gravity of the injection material. If the pumping distance of the cement air milk to the mixer for mixing the air milk and the bentonite milk by the pumping tube is long, bubbles disappear from the cement air milk in the pumping tube, and predetermined bubbles are formed in the injection material mixed by the mixer. Is not included.

Further, even when an injection material containing air bubbles at a predetermined ratio is filled in a predetermined injection site, water enters the air bubbles of the injection material being cured, and the specific gravity of the injection material increases. was there. Further, in the above-mentioned application, although it is possible to reduce the specific gravity of the cement milk by mixing the air bubbles into the cement milk to form the cement air milk, there is no solution to increasing the specific gravity of the cement milk.

[0013]

Means for Solving the Problems As a result of various studies to solve the above problems, the present inventors have found that bentonite is aggregated by the action of cations as in the previously filed invention, and that In order to promote rapid agglomeration using calcium ions of cement as ions, cement milk and bentonite milk are stirred and mixed, and further, by selecting granules mixed with these, this mixture is rapidly plasticized, and It is found that an excellent plastic injection material having a desired specific gravity can be obtained without being separated by,
The present invention has been completed.

That is, the present invention, which is means for solving the above-mentioned problems, comprises:
Using bentonite, a natural mineral that is chemically stable and inexpensive and readily available, is used as a plasticizer and formed by stirring and mixing cement milk or cement air milk, bentonite milk, and granules for specific gravity adjustment. To provide a plastic injection material.

The granules for adjusting the specific gravity are not particularly limited as long as the specific gravity of the plastic injectable material can be adjusted. The granules of the cement milk or the bentonite milk do not separate from the cement milk or the bentonite milk. Granules to be used can be selected according to the properties. Lightweight aggregates for soil or non-structural lightweight concrete such as expanded beads, perlite and vermiculite are used to reduce the specific gravity, and natural sand, gravel, limestone aggregate and natural weight are used to increase the specific gravity. Use is made of aggregates or artificial aggregates or artificial weight aggregates such as blast furnace slag, ferronickel slag and copper slag, or structural lightweight concrete aggregates such as expanded shale, fired fly ash and volcanic gravels. As described above, aggregates and the like generally used for concrete are used as granules for specific gravity adjustment,
In particular, foam beads and sand or gravels are preferable because they can be easily procured, are inexpensive, have a large difference in specific gravity from the plastic injection material, and can be adjusted so as not to be separated from milk.

In the present invention, the above-mentioned granules are foamed beads, and are plastic injection materials. here,
The expanded beads are particles having an expansion ratio of 10 to 80 times and a diameter of 1 to 9 mm. By mixing the foamed beads into the plastic injection material, the specific gravity of the plastic injection material can be made lighter than the plastic injection material obtained by kneading cement milk and bentonite milk. During the pumping, the foam beads are prevented from separating from the cement milk or the cement air milk.

In the state where it is injected at the injection point,
Since the water in the earth and sand does not enter the foamed beads of the injection material, the specific gravity of the injection material during curing does not increase.

Further, in the present invention, the above-mentioned granular material is sand,
And a plastic injection material characterized in that it is at least one selected from gravels and gravel.

Here, those having a maximum particle size of 2 mm or less are called sand, and those having a maximum particle size exceeding 2 mm are called gravel. 15% or less of fine particles of 75μm or less as sand or gravel
The following is preferred. If the content of fine particles exceeds 15%, the fluidity decreases, which is not preferable. It is preferable that the gravel has a maximum particle size of 5 mm or less. Maximum particle size is 5m
If it exceeds m, the fluidity also decreases, which is not preferable.

By mixing sand, gravel and the like into the plastic injection material, the specific gravity of the plastic injection material can be made heavier than that of the plastic injection material obtained by kneading cement milk or cement air milk and bentonite milk. For this reason, the injection | pouring material can fill a predetermined | prescribed location, without floating in water, even if it inject | pours in water.

In the present invention, the plastic injection material is
The mixing ratio of cement to water is 1: 0.3 to 1: 1 by weight.
Of cement air or of cement and water at a weight ratio of 1: 0.3 to 1: 1 of cement air milk, and of bentonite and water at a weight ratio of 1: 4 to 1:12.
It is preferably formed by stirring and mixing with bentonite milk.

Further, in the present invention, it is preferable that the plastic injection material has a swelling power of bentonite of 15 or more.

In the present invention, it is preferable that the mixing volume of the plastic injection material is 60% or less with respect to the volume of the plastic injection material.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the plastic injection material of the present invention, first, A
Cement milk (comprising cement, water, various admixtures as necessary) or cement air milk (compounding cement, water, air bubbles, various admixtures as necessary) is prepared as a liquid, and separately from this, bentonite milk (liquid B) is prepared separately. Bentonite, water and, if necessary, various admixtures) are prepared. Then, the liquid A and the liquid B are mixed and plasticized instantaneously. Granules for specific gravity adjustment are A
Solution, or solution B, or both.

The cement used for the liquid A may be any of various types of portland cements such as ordinary, high-strength, ultra-high-strength, white, sulfate-resistant, moderate heat and low heat. It can be selected from a mixed cement mixed with one kind, a super-hardened cement (for example, Jet Cement (registered trademark)), a special cement such as alumina cement, and a cement-based solidified material.

The cement milk may be mixed with air bubbles obtained by subjecting a foaming agent to a foaming treatment as needed to form a cement air milk. Granules for adjusting specific gravity are mixed with the cement milk, the cement air milk or the bentonite milk. The particles for adjusting the specific gravity may be mixed with one or both of the liquid A and the liquid B.

As granules for adjusting the specific gravity, foamed beads are suitable for decreasing the specific gravity, and sand or gravel is suitable for increasing the specific gravity.

The expanded beads are ultra-lightweight granules formed by evaporating a synthetic resin such as polystyrene using steam or hot air. Depending on the type of foam beads, styrene foam, polypropylene foam, and vinylidene chloride foam can be used. Of these, Styrofoam (EPS) is commonly used. This EP
The raw material of S is composed of polystyrene and a foaming agent such as propane, butane, and pentane. By foaming, E is excellent in ultralight weight, compression resistance, water resistance, and heat insulation.
PS.

As the conjugate beads, those having an appropriate diameter among diameters of about 1 to 9 mm are used. These foam beads can be controlled in size and the like according to the application, and in some cases, crushed pieces of EPS waste can be used.

The total mixed volume of the bubbles and the granules for adjusting the specific gravity in the plastic injection material is 60 times the amount of the plastic injection material.
% By volume or less is preferred. If the total amount of the bubbles and the granules for adjusting the specific gravity exceeds 60%, the mixing amount of the bubbles and the granules for adjusting the specific gravity is too large. As a result, the amount of cement and bentonite used is too small, and therefore, It is difficult to develop the strength of the cured product of the plastic injection material.

If necessary, an admixture such as a water reducing agent may be added to the liquid A cement milk or cement air milk. The addition of the admixture does not affect the plasticity after kneading. Further, since the unit water amount in the liquid A can be reduced or the unit cement amount can be increased by adding the water reducing agent, the strength can be increased. In addition, if there is a possibility of material separation in the liquid A cement milk or cement air milk, a small amount of bentonite can also be added to the liquid A as needed for the purpose of preventing material separation.

The quality of the bentonite used in the solution B is not particularly limited, but bentonite having a swelling force of 15 or more is preferred. Here, the swelling force is determined by the test method of the Japan Bentonite Industry Association (JBAS-104), and is expressed by the apparent volume occupied in distilled water when bentonite is gradually dropped into water. That is, distilled water 1
A 2 g bentonite sample was dropped into 00 ml (milliliter), left for 24 hours after dropping, and the apparent volume of the sample deposited in the container was read. Therefore, the unit of the swelling force is ml (milliliter) / 2 g.

When the swelling force is less than 15, it is necessary to increase the amount of bentonite, and it is not preferable because material separation easily occurs. Further, when it is necessary to reduce the weight of the plastic injection material, it is necessary to reduce the amount of bentonite used, and for that purpose, it is optimal to use bentonite having a swelling force of 15 or more.

[0034] When using a swelling power of 15 or more bentonites, the addition amount thereof is preferably approximately 80~120kg / m about ^{3, 100~120kg} / m ³ and more preferably. 80 kg
If it is less than / m ³ , material separation may occur during submerged casting, and if it is 50 kg / m ³ or less, the plasticizing effect is low. Also, 1
If it exceeds 20 kg / m ³ , bentonite tends to lump during the preparation of the solution B, making it difficult to prepare uniform bentonite milk. It is necessary to add a general bentonite dispersant. On the other hand, if it is 150 kg / m ³ or more, kneading is difficult and uneconomical even if a dispersant is added.

The ratio of water to bentonite in solution B is preferably 4 or more. If the ratio of water to bentonite is less than this, bentonite is liable to be formed during preparation of solution B,
It is difficult to prepare a uniform bentonite milk, and it is necessary to add a general bentonite dispersant.

The present invention relates to A prepared in advance as described above.
Liquid and liquid B are mixed in a milk state. Liquid A cement milk or cement air milk is in a suspended state in which the aqueous solution is supersaturated with calcium ions released from the cement,
Filled with positive calcium ions.

On the other hand, bentonite milk of liquid B has bentonite swelling and is charged with negative ions. By mixing such milk with each other, calcium plus ions neutralize the negative charge on the surface of the bentonite particles, causing a rapid agglutination reaction due to the intermolecular attraction of the bentonite particles, which can be instantaneously plasticized. is there.

As described above, mixing of milk is indispensable in order to plasticize instantaneously and uniformly. As in the above-described method of preparing a cement-bentonite suspension, cement powder is mixed with bentonite milk. If so, it takes time to dissolve the calcium ions, and it is difficult to plasticize instantly.

The mixing ratio of the liquid A and the liquid B in the present invention is appropriately determined according to the purpose of use. The kneading time is preferably about 15 seconds or less with a hand mixer,
Further kneading is not preferable because material separation easily occurs.

The flow value of the prepared plastic injection material was 80 (independent) by the cylinder method, which is a standard test method of the Japan Highway Public Corporation.
It is preferably from 150 to 150 mm, more preferably from 80 to 120 mm. With a thickness of 80 to 120 mm, the material is optimal as a plastic injection material, and can be used with very little material separation even in a place where it is poured underwater or in a place where running water is present. In addition, when the thickness is 120 to 150 mm, it can be sufficiently used as a plastic injection material when it is not affected by flowing water or the like. However, when it is used for casting underwater, turbidity and cracks may be generated in the material. Those with a diameter of 150 mm or more are close to the fluidity of ordinary air mortar and air milk and are not suitable for limited injection.

A of the total water amount in the compounding material of the plastic injection material
There is no particular limitation on the change in the amount of distribution between the liquid and the liquid B. However, in order to increase the material separation resistance of the cement milk of the liquid A, a range in which a homogeneous cement milk can be prepared (when a water reducing agent or the like is used) , Including cement: water = 1: 0.3-1: 1
), The water of the liquid A should be reduced as much as possible.

Further, in order to improve the plasticizing performance, it is necessary to disperse the bentonite milk of the liquid B more uniformly, and for that purpose, it is necessary to increase the amount of water of the liquid B. That is, when the total amount of water is kept constant, it is optimal to minimize the amount of the solution A and increase the amount of the solution B as much as possible within a range where the uniform mixing performance is not reduced. But bentonite:
When the amount of water is larger than water = 1: 12, the total amount of water is increased, so that separation becomes easy, and the strength of the cured product of the plastic injection material is undesirably reduced.

[0043]

The method of the present invention will be further described with reference to the following examples. In the following examples, preparation methods, test materials, and test methods of the injection material are as follows. The present embodiment describes one embodiment of the present invention, and the present invention is not limited by the embodiment.

(Preparation method) The liquid A is prepared by kneading the cement-based solidifying material and water with a hand mixer for 2 minutes, and then, in the case of a lighter weight, air bubbles (foaming agent) so as to have a predetermined mixing amount. Was diluted 25 times with water and then foamed 25 times)
Alternatively, foamed beads were charged and mixed with a hand mixer for 30 seconds to prepare. In the case of weight increase, as in the case of weight reduction, sand and gravel were further charged and mixed by a hand mixer for 30 seconds.

Solution B was prepared by kneading bentonite and water with a reciprocating stirring mixer for 5 minutes. Mixing of liquid A and liquid B
It was prepared by kneading with a hand mixer for about 10 to 15 seconds.

(Test Materials) Materials used for the test are as follows. Cement: Cement-based solidifying material manufactured by Sumitomo Osaka Cement Co., Ltd. Trademark: “Tafloc” Plasticizer: Bentonite A (swelling force 16.0): Bentonite B (swelling force 8.0) Foaming agent: Sumitomo Osaka Cement Brand name: "Sumishield A" Admixture: High performance water reducing agent manufactured by Kao Corporation Brand name: "Mighty 150" Foam beads: Styrofoam 50-fold foam Specific gravity 32
g / l (liter) Average particle size 2mm Gravel (mixture of sand and gravel): Kisarazu City, Chiba Prefecture
%, Sand content 90%, fine grain content 6%), density 2.68 g / cm ³

(Test Items) As test items, “measurement of specific gravity of specimen”, “change in specific gravity of specimen in underwater curing”,
"Confirmation of defoaming state of specimen", "measurement of flow value", and "performance judgment of plasticization" were performed.

The flow value was determined according to the Japan Highway Public Corporation Standard “Air mortar and air milk test method (JHSA).
313-1992) ", the cylinder method of the consistency test method. This was measured by placing a sample in a cylinder having an inner diameter of 8 cm and a height of 8 cm, and measuring the diameter of the bottom surface of the sample after withdrawal.

The plasticization performance was evaluated by the method of testing the degree of separability of underwater non-separable concrete underwater, Appendix 2, Guideline for Design and Execution of Underwater Non-separable Concrete. That is, 800cc in a 1000cc beaker in advance
, And 500 g of the plastic injection material was divided into 10 parts, and the divided parts were poured from above the water surface using a spatula, and the state of suspension was visually observed and judged according to the following criteria. In this test, the better the plasticization, the better the plastic infused material obtained, the stronger the gel, and the lower the suspension in water, the less the suspension.
That is, the plasticizing performance and the degree of suspension are in a negative correlation.

The criteria are as follows. [Contents] [Contents of judgment] [Symbol] Excellent plasticization: No suspension at all. ……… ◎ Good plasticization… Slight suspension is observed. ………… Poor plasticization… There is suspension. ……… △ Not plasticized… Not plasticized and not used in this test. … ×

Example 1 In this example, the density of a specimen mixed with granules for adjusting specific gravity was measured. In this example, A
Do not mix a liquid sample with foamed beads mixed with granules for specific gravity adjustment (formulation 1), a sample mixed with sand and gravel as granules for specific gravity adjustment (formulation 2), and granules for specific gravity adjustment. Specimens (formulations 3, 4, and 5) were prepared, and their specific gravities were measured. Table 1 shows the results.

[0052]

[Table 1]

From the results shown in Table 1, Formulation 1 in which expanded beads were added to Formulation Examples 3, 4, and 5 in which no granules for adjusting the specific gravity were added, had a low specific gravity, and Formulation 2 in which sand and gravel were added was Formulation 2. From the fact that the specific gravity is large, it can be seen that the specific gravity of the injected material can be adjusted in a larger range by adding the specific gravity adjusting granules as compared with the case where the specific gravity adjusting granules are not added.

Example 2 In this example, the density of a test specimen in underwater curing was measured. Specimen in which only bubbles were mixed in liquid A, and in which only foam beads were mixed (φ5 cm × H1
0 cm) were prepared, each specimen was cured in water, and the density of the specimen was measured after a predetermined time. According to this test, it can be seen that the less the density of the specimen increases, the less infiltration of groundwater or the like into the injected material after injection / filling.
Table 2 shows the composition of the specimen mixed with air bubbles alone, Table 3 shows the composition of the specimen mixed with foam beads, and Table 4 shows the density change of each specimen. In addition, of the units in Tables 2 and 3, kg / m
³ and l / m ³ illustrates the relevant ingredient amounts in plastic injection material 1 m ³ of (kg, l).

[0055]

[Table 2]

[0056]

[Table 3]

[0057]

[Table 4]

According to Table 4, while the density of the specimen mixed with the bubbles increased, the density of the specimen mixed with the expanded beads hardly changed. It can be seen that there is little infiltration of groundwater and the like into the injection material.

Example 3 In this example, the defoaming state of the specimen was checked. A liquid prepared by mixing bubbles or foam beads with the A liquid or the B liquid is prepared according to the following formulation, and while each liquid is continuously kneaded by a Hobart mixer, immediately before kneading, 5 minutes after kneading, 10 minutes after kneading, and Fifteen minutes after the kneading, samples were kneaded three times each and the density was measured, and the defoaming was determined based on the magnitude of the density change. The density immediately before kneading was calculated from the density of each material before kneading.

According to this test, solution A was pumped
Kneading each liquid continuously assuming the case of transporting liquid B,
Based on the result of measuring the density change of each liquid, it can be determined that the greater the density change, the greater the degree of defoaming. Table 5 shows the composition of Liquid A, Table 6 shows the composition of Liquid B, and Table 7 shows the state of density change.

[0061]

[Table 5]

[0062]

[Table 6]

[0063]

[Table 7]

According to Table 7, it can be seen that the density tends to increase when the liquid is mixed with the liquid A and the liquid B, while the density does not change when the mixed beads are used. That is, it can be seen that the degree of defoaming is small when the liquid A and the liquid B are conveyed by pumping when foam beads are mixed.

Example 4 In this example, a test was conducted with the cement-based solidifying material amount, the bentonite amount and the total water amount kept constant, while changing the mixing amount of water when preparing cement milk and bentonite milk. Among the units in Table 8-10, a kg / m ³ and l / m ^3, showing the relevant ingredient amounts in plastic injection material 1 m ³ of (kg, l). Table 8 shows the amounts of cement milk and bentonite milk and the test results.

[0066]

[Table 8]

From Table 8, it can be seen that even with the same amount of material used, the plasticizing performance varies depending on the distribution of water. This is because plasticizing performance is improved by improving the dispersibility of bentonite in the liquid B. Therefore, it is understood that it is preferable to allocate a large amount of water of the solution B within a range in which the composition can be set. Since the cement-based solidifying agent: water = 1: 0.5 is good, the lower limit of the amount of water in the solution A is as follows.
Water = 1: 0.3, cement-based solidifying material: water = 1: 1.
Since No. 1 is defective, the upper limit of the amount of water in the solution A is set to cement-based solidifying material: water = 1: 1.

Example 5 In this example, tests were conducted by changing the amounts of cement-based solidifying material and bentonite added. Table 9 shows the amounts of cement-based solidifying material and bentonite added,
The flow value of plasticity after mixing and the property judgment are also shown. In this example, the cement-based solidification material: water was kept constant at 1: 0.5.

[0069]

[Table 9]

According to Table 9, bentonite: water = 1: 5.
Extrapolating the flow values of 2: 1, 6.3, 1: 8 gives
It can be seen that bentonite: water = 1: 12 is the upper limit of the amount of water in the solution B. In addition, since the flow value suitable as the plastic injection material is 80 mm or more, it can be seen that the lower limit of the amount of water in the B liquid is about 1: 4: bentonite: water in the B liquid.

Example 6 In this example, a test was conducted in which bentonite milk was prepared using bentonite A having a swelling force of 16.0 and bentonite B having a swelling force of 8.0. Table 10 shows the blending amounts of the solution A and the solution B, and the test results.

[0072]

[Table 10]

According to Table 10, plasticization is possible even when bentonite B having a swelling force of less than 15 is used (formulation 3: Example), but when bentonite A is used (formulation 1:
It can be seen that the amount of addition increases as compared with Example). Further, it can be seen that when bentonite B was used, it could not be used if the added amount was further increased (Formulation 4: Comparative Example). From the above, it is understood that the swelling force of bentonite is preferably 15 or more.

[0074]

As described above, according to the present invention, bentonite, which is a chemically stable, inexpensive and easily available natural mineral, is used as a plasticizer, and is used for cement milk or cement air milk. An object of the present invention is to provide a plastic injection material formed by stirring and mixing bentonite milk and granules for specific gravity adjustment. In the present invention, if the granules are expanded beads, the specific gravity of the plastic injectable material can be as light as that of the plastic injectable material obtained by kneading cement air milk and bentonite milk. An effect is obtained in that the foamed beads are prevented from being separated from the cement milk during the pressure feeding until both milks are kneaded. In addition, the above granules are sand,
By using gravel, the specific gravity of the plastic injection material can be made greater than that of the plastic injection material obtained by kneading cement milk or cement air milk and bentonite milk. It has the effect that it can be done.

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Claims (6)

[Claims] 1. A plastic injection material formed by stirring and mixing cement milk or cement air milk obtained by mixing air bubbles with cement milk and bentonite milk,
A plastic injection material characterized in that granules for adjusting specific gravity are mixed in the plastic injection material. 2. The plastic injection material according to claim 1, wherein the granules are foam beads. 3. The plastic injection material according to claim 1, wherein the granules are at least one selected from sand and gravel. 4. The mixing ratio of cement to water in cement milk or cement air milk is 1: 0.3 to 1: 1 by weight, and the mixing ratio of bentonite to water in bentonite milk is The plastic injection material according to claim 1, wherein the weight ratio is from 1: 4 to 1:12. 5. The plastic injection material according to claim 1, wherein the bentonite has a swelling force of 15 or more. 6. The method according to claim 1, wherein a total mixing volume of bubbles and particles for adjusting specific gravity with respect to a volume of the plastic injection material is 60% or less. 6. The plastic injection material according to 5.