JPH11310779A - Plastic grout - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a grout which is quickly plasticized and does not separate in water by mixing under stirring a cement milk or a cement air milk comprising a cement milk and air bubbles contained therein with a bentonite milk. SOLUTION: A cement milk comprising cement and water in a wt. ratio of (1/0.3)-(1/1) or a cement air milk prepd. by incorporating air bubbles into a mixture of cement and water in a wt. ratio of (1/0.3)-(1/1); if necessary and additive agent such as a water reducing agent; and a bentonite milk prepd. from bentonite (80-120 kg/m<3> ) having a swelling power of 15 (ml/2 g) or higher and water in a wt. ratio of (1/4)-(1/12) are mixed and kneaded for about 15 sec with, e.g. a hand mixer to give the objective grout which contains air bubbles in an amt. of up to 60 vol.% and has a density of 0.6-1.2 g/cm<3> and a flow value (the cylinder method) of 80-150 mm. The cement used is selected from among portland cement, a blended cement, a special cement, and a cement- based solidifying material.

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 injectable material which 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 there is groundwater or running water in a cavity filling portion,
To prevent the injection material from being diluted into groundwater or 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 state of gelled aggregates, without being diluted by groundwater or running water, due to its shape imparting property, it is difficult for deviation to the surroundings to occur, hereinafter referred to as "plasticity" I do.

[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.

Further, a cement-bentonite suspension is conventionally known as an injection material. Although this cement-bentonite suspension has an effect of increasing viscosity, it cannot be made into a plastic state. Not practically used for injection. As a procedure for preparing a 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, which has 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.

Therefore, conventionally, a material which is chemically stable, has excellent durability, is inexpensive and is easily available, instantly becomes a plastic body, and can reliably fill a cavity even under limited injection or flowing water. An injection material to be performed was desired.

[0010]

Means for Solving the Problems The present inventors have conducted various studies to solve the above-mentioned problems, and as a result, have noticed the effect that bentonite is aggregated by the action of cations. Using cement as cement milk to promote rapid agglomeration, this mixture is rapidly plasticized when cement milk and bentonite milk are stirred and mixed, and is an excellent plastic filler that does not separate in water. Was obtained, and the present invention was completed.

That is, the present invention, which is means for solving the above-mentioned problems, comprises:
Provided is a plastic injection material formed by stirring and mixing cement milk or cement air milk with bentonite milk using bentonite which is a chemically stable, inexpensive and readily available natural mineral as a plasticizer. Is what you do.

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, the plastic injection material preferably has a swelling force of 15 or more of bentonite.

In the present invention, it is preferable that the plastic injecting material has an air bubble mixing amount of 60% or less based on the volume of the plastic injecting material.

[0015]

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.

The cement used for the liquid A is usually Portland cement of various types, such as normal, high strength, ultra-high strength, white color, sulfate resistance, moderate heat and low heat, and at least one of the above Portland cements and at least one of blast furnace slag and fly ash. It can be selected from mixed cements mixed with one kind, special cements such as jet cement and alumina cement, and cement-based solidified materials.

The cement milk may be mixed with air bubbles obtained by subjecting a foaming agent to a foaming treatment, if necessary, to obtain cement air milk. The mixing amount of air bubbles is preferably 60% by volume or less of the amount of the plastic injection material, and the density is 0.6 g / cm ³ to 1.2 g / cm 2 depending on the amount of air bubbles.
Arbitrary density setting of about cm ³ is possible. Density 0.6g / c
For than about m ^3, the result bubbly Too much being mixed than 60% of the bubbles, the amount of cement and bentonite becomes too small, therefore, cured strength and plasticity injection material plasticity body It becomes difficult to express the strength of the body.

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. In addition, the addition of the water reducing agent can reduce the unit water amount in the solution A or increase the unit cement amount, so that it is possible to expand the range of the mixing setting for high strength and light weight. 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 for the liquid 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 Japan Bentonite Industry Association Test Method (JBAS-104) and is expressed as the apparent volume occupied in water when bentonite is gradually dropped into distilled water or pure water. You.
That is, 2 g of a bentonite sample is dropped into 100 ml (milliliter) of pure water or distilled water, allowed to stand for 24 hours after dropping, and the apparent volume of the sample deposited in the container is read. Therefore, the unit of the swelling force is ml (milliliter) /
2 g.

If 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.

[0021] 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. 80kg /
If it is less than m ³ , material separation may occur during submerged casting and the like, and if it is 50 kg / m ³ or less, the plasticizing effect is low. Also, 12
If it exceeds 0 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 the 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 the preparation of A prepared as described above.
Liquid and liquid B are instantaneously mixed in a milk state. The liquid A cement milk or cement air milk is a suspension in which the aqueous solution is supersaturated with calcium ions released from the cement, and is 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, it is essential to mix milk with each other in order to plasticize instantaneously and uniformly. As in the above-described method for 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 solution A and the solution B in the present invention is appropriately determined according to the purpose of use. The kneading time is preferably about 15 seconds or less using a hand mixer, and longer 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 to 1:
In about 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.

[0030]

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.

(Preparation method) Solution A was prepared by kneading a cement-based solidifying material and water for 2 minutes using a hand mixer. When mixing bubbles, bubbles (foaming agent diluted 25-fold with water and then 25-fold foamed) were added so as to have a predetermined mixing amount, and mixed with a 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 in 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"

(Test Method) “Flow value” was used as a test item.
, "Strength", and "plasticization performance determination" were performed according to the following criteria.

[0035]Flow value  Japan Highway Public Corporation Standards “Test of air mortar and air milk”
Method (JHSA 313-1992) "
According to the cylinder method of the sea test method
Place the sample in the cylinder and pull the sample
Measure diameter

[0036]Strength  The strength of the cured product of the plastic injection material was measured as follows. Japanese Geotechnical Society standard “Uniaxial compression test (JIS A1216)
 ) ”Specimen size φ5 × 10cm, each age 3 Curing conditions are as follows Aerial curing: 1 day after age, remove from mold, wrap in wrap, 20 ° C constant temperature room
Curing Underwater curing: Demold after 1 day of age, 10 times the volume of the specimen in the container
Water and cure in water at 20 ℃ until the strength test date

[0037]Judgment of plasticization performance  Japan Society of Civil Engineers Annex 2
The test was conducted using the underwater separation test method for non-separable concrete.
Test was carried out. That is, 80
Pour 0cc of water and 500g of plastic injection material into 10
Then, use a spatula to divide the water into the water, and suspend
The situation was visually observed and judged according to the following criteria. In this test
The better the plasticization, the better the plastic injection material obtained.
Is strong and there is little suspension even when descending in water
become. In other words, the plasticization performance and the degree of suspension are negatively correlated.
It is in.

The criterion is as follows.

Hereinafter, embodiments of the present invention will be described. Example 1 In this example, a test was conducted by changing the composition of cement milk, cement air milk and bentonite milk. Table 1 shows the composition examples, and Table 2 shows the properties, strength and judgment.

[0040]

[Table 1]

[0041]

[Table 2]

From Formulations 1 to 5 in Table 2, a flow value of 100 was obtained by mixing solutions A and B having high fluidity, respectively.
It can be seen that a good plastic material of ~ 110 mm is obtained. In addition, it can be seen from the Formulations 1 to 3 that by adding an appropriate amount of the cement-based solidifying material and bentonite, a plastic injection material whose strength can be arbitrarily set can be produced. Also, it can be seen that a good plastics injection material can be produced even if the air bubbles are mixed from Formulations 4 and 5.

Example 2 In this example, a test was carried out by changing the procedure of preparing the injection material while using the same amount of cement-based solidifying material and bentonite. Table 3 shows the preparation procedure, and Table 4 shows the test results.

[0044]

[Table 3]

However, the kneading method in this case is as follows. A liquid plain ........ hand mixer 2 minutes kneading liquid B PLAIN ....... reciprocating stirring mixer 5 minutes kneading A liquid + B solution ....... hand mixer 15 seconds kneading Liquid + powder ... 1 to 3 minutes hand mixer kneading (where powder + liquid is liquid A + bentonite powder, liquid B + cement-based solidifying material powder, cement-based solidifying material powder + bentonite It is the case of powder + water.)

[0046]

[Table 4]

From Table 4, it can be seen that the preparation method capable of favorably plasticizing the injection material is only two-liquid mixing of preparation method type 1 (Example). That is, in the same type 2 (Comparative Example), the cement-based solidifying material does not disperse and the plasticizing effect is low, and even if kneading is performed until the lumps disappear, the fluidity is improved and the plasticizing effect is weakened. The same type 3, 4 (comparative example) has no plasticizing effect at all.

Example 3 In this example, a test was conducted by adding a water reducing agent to solution A. Table 5 shows the compounding amounts of the cement-based solidifying material and the bentonite of the liquid A and the liquid B, and Table 6
Shows the results of a test in which a high-performance water reducing agent was added to the water of the solution A on an outer basis.

[0049]

[Table 5]

[0050]

[Table 6]

Table 6 shows that the addition of a water reducing agent to increase the fluidity of the solution A does not affect the plasticity after kneading.

Example 4 In this example, a test was carried out 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. Table 7 shows the amounts of cement milk and bentonite milk and the test results.

[0053]

[Table 7]

It can be seen from Table 7 that even with the same amount of material used, the plasticizing performance changes depending on the distribution of the amount 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.

Example 5 In this example, tests were conducted by changing the amounts of cement-based solidifying material and bentonite added. Table 8 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, cement-based solidification material: water = 1: 0.5
And constant.

[0056]

[Table 8]

According to Table 8, the amount of bentonite A added was almost 80 to 120 kg / m irrespective of the amount of cement-based solidifying material added.
It is understood that about ³ is preferable, and 100 to 120 kg / m ³ is optimal.

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 9 shows the compounding amounts of the liquid A and the liquid B and the test results.

[0059]

[Table 9]

According to Table 9, plasticization is possible even when bentonite B having a swelling force of less than 15 is used (formulation 3:
It can be seen that the addition amount increases in Example) as compared with the case of using bentonite A (Formulation 1: Example). Also,
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.

[0061]

As described above, according to the present invention, a cement-based material and bentonite, which is a chemically stable natural material, are respectively mixed with water to form cement milk or cement air milk and bentonite milk. The resulting plastic is used as an injection material. Therefore, according to the plastic injection material of the present invention, since bentonite which is chemically stable without elution of alkali ions or salt ions is used as the plasticizer, groundwater, river water, lake water and the like are used. Even if it is used as an injection material for water stoppage, gap filling, underwater cavity filling, etc. in civil engineering work, there is no risk of environmental pollution and durability is maintained for a long period of time. In addition, since bentonite is inexpensive and easily available, the cost of the plastic injection material can be reduced. In addition, since liquid cement milk or cement air milk and liquid bentonite milk are mixed, the injection material is in a plastic state immediately after mixing both liquids, so that the cavity can be reliably filled, This has the effect that it can be applied to lightweight embankments and landfills.

Claims (4)

[Claims] 1. A plastic injection material formed by stirring and mixing cement milk or cement air milk in which air bubbles are mixed into cement milk, and bentonite milk. 2. A cement milk having a mixing ratio of cement and water of 1: 0.3 to 1: 1 by weight, or a mixing ratio of cement and water of 1: 0.3 to 1: 1 by weight. The plastic injection material according to claim 1, which is formed by stirring and mixing cement air milk of the formula (1) and bentonite milk with a mixing ratio of bentonite and water of 1: 4 to 1:12 by weight. 3. The plastic injection material according to claim 1, wherein the swelling force of the bentonite is 15 or more. 4. The plastic injection material according to claim 1, wherein a mixing amount of bubbles with respect to a volume of the plastic injection material is 60% or less.