JP7349462B2 - Filling material for ground preparation - Google Patents

Description

The present invention relates to a material for filling cavities existing in the ground, in gaps between the ground and structures, in submerged ground, and in gaps between the ground and structures.

Filling materials used to fill cavities created between existing structures and subsided ground, cavities created behind bridge abutments and revetments, and cavities created around sluice gates and sluice structures require injection pressure. When shearing force is applied, it easily deforms and flows, but in the absence of pressure, it is necessary to have high workability and fillability due to the ability to maintain shape. Furthermore, even in filling at the water's edge due to no-dilution performance, it is also necessary that there be no flow down or dilution after filling.

As such a filling material, for example, in Patent Document 1, a flow cone is placed on a horizontally placed glass plate, and a grout material made of water and cement as the main raw materials with additives added to the flow cone. The grout is poured continuously, the flow cone is pulled up vertically, and the flow value, which is the average value of the maximum width of the grout spread on the glass plate and its vertical width, is 100 to 200 mm, and the grout is stored in a closed container. , the grout inside the funnel is filled with the grout material, the outlet of which is exposed from the airtight container, compressed air is sent into the airtight container, and a pressure of 0.1 MPa is applied from atmospheric pressure to the grout inside the funnel. A thixotropic grout material is disclosed that has a flow time of 0.5 to 3.0 seconds until the material completely flows down from the outlet of a funnel.

JP2004-284930A

However, filling materials for ground preparation are used to fill cavities between existing structures and subsided ground, cavities that occur behind bridge abutments and embankments, and cavities that occur around sluice gates and sluice pipe structures. , it is necessary to have sufficient fluidity during pouring, and it is necessary to remain in place when no pressure is applied. In addition, it must be difficult to separate in water even if it is cast in water, and it must have high stability in water.

However, most of the filling materials used in Patent Document 1 are grout materials that are a mixture of cement and water, and there is a problem that the grout material becomes high in strength after filling. If the filled area is highly strong, it may cause problems in the later stages of construction. In filled areas with high strength, a boundary may occur between the filled area and the original ground, forming a new water path and potentially becoming a weak area. In addition, the strength of these filled areas is difficult to control and difficult to consider as a structure.

It is therefore an object of the present invention to provide a filling material for filling various cavities, which has sufficient fluidity when the pressure pump is installed, and which has the property of being non-flowing when no pressure is applied. To provide a filling material for ground preparation which has high stability and does not separate in water.

The above-mentioned problems of the present invention are solved by the following present invention.
That is, the present invention (1) contains at least sand particles, montmorillonite particles, a polymer compound having an anionic functional group in its molecular chain, and water,
The tabular combinations of montmorillonite particles are connected in a three-dimensional direction, and the sand particles are covered by the tabular combinations of montmorillonite particles to hold the sand particles;
The tabular bond of montmorillonite particles is formed by bonding the sides of the montmorillonite particles with the molecular chain of the polymer compound, thereby bonding a plurality of montmorillonite particles via the polymer compound. is being done,
The present invention provides a filling material for ground preparation characterized by the following.

Further, the present invention (2) is characterized in that the polymer compound having an anionic functional group in the molecular chain is a linear anionic polymer compound that is a copolymer of acrylic acid and acrylamide. The present invention provides a filling material for ground preparation according to (1).

In addition, the present invention (3) provides that the mass ratio of the polymer compound having an anionic functional group in the molecular chain to the montmorillonite particles (polymer compound/montmorillonite particles) is from 0.020 to 0.50. The present invention provides a filling material for ground preparation according to (1) or (2), which is characterized by the following.

Moreover, the present invention (4) is characterized in that the mass ratio of the montmorillonite particles to the sand particles (montmorillonite particles/sand particles) is 0.010 to 0.20. The present invention provides filling materials for ground preparation.

In addition, the present invention (5) provides that the mass ratio of the polymer compound having an anionic functional group in the molecular chain to the sand particles (polymer compound/sand particles) is from 0.0050 to 0.020. The present invention provides a filling material for ground preparation according to any one of (1) to (4) characterized by the following.

In addition, the present invention (6) provides that the mass ratio of the montmorillonite particles to water in the filling material for ground preparation (montmorillonite particles/water in the filling material for ground preparation) is 0.010 to 0.30. The present invention provides a filling material for ground preparation according to any one of (1) to (5) characterized by the following.

In addition, the present invention (7) provides a mass ratio of the polymer compound having an anionic functional group in the molecular chain to water in the filler material for ground preparation (polymer compound/water in the filler material for ground preparation). is 0.0050 to 0.025, the filling material for ground preparation according to any one of (1) to (6).

According to the present invention, it is an object of the present invention to provide a filling material for filling various cavities, which has sufficient fluidity when a pressure pump is installed, and has a non-flowing property when no pressure is applied. Moreover, it is possible to provide a filling material for ground preparation that does not separate in water and has high stability. Furthermore, since this filling material is mainly composed of sand material, it does not exhibit high strength.

BRIEF DESCRIPTION OF THE DRAWINGS It is a typical sectional view for demonstrating the structure of the filling material for ground preparation of this invention. FIG. 2 is a schematic diagram for explaining a tabular combination of montmorillonite particles. It is a SEM photograph (100 times) of the cross section of the filling material for ground preparation of Example 1. It is a SEM photograph (200 times) of the cross section of the filling material for ground preparation of Example 1.

The filling material for ground preparation of the present invention contains at least sand particles, montmorillonite particles, a polymer compound having an anionic functional group in its molecular chain, and water,
The tabular combinations of montmorillonite particles are connected in a three-dimensional direction, and the sand particles are covered by the tabular combinations of montmorillonite particles to hold the sand particles;
The tabular bond of montmorillonite particles is formed by bonding the sides of the montmorillonite particles with the molecular chain of the polymer compound, thereby bonding a plurality of montmorillonite particles via the polymer compound. is being done,
This is a filling material for ground preparation that is characterized by:

EMBODIMENT OF THE INVENTION With reference to FIG.1 and FIG.2, the filling material for ground preparation of this invention is demonstrated. FIG. 1 is a schematic cross-sectional view for explaining the structure of the filling material for ground preparation of the present invention. FIG. 2 is a schematic diagram for explaining a combination of montmorillonite particles. In FIG. 1, a filling material 1 for ground preparation includes a tabular combination 2 of montmorillonite particles and sand particles 3 covered with the tabular combination 2 of montmorillonite particles. In the ground preparation filling material 1, the tabular combinations 2 of montmorillonite particles are connected in a three-dimensional direction, and the tabular combinations 2 of montmorillonite particles cover the sand particles 3. That is, the sand particles 3 are held in the ground preparation filling material 1 by being covered by the tabular combinations 2 of montmorillonite particles connected in a three-dimensional direction.

In FIG. 2, a tabular combination of montmorillonite particles 2 is formed of montmorillonite particles 11 and a polymer compound 12 having an anionic functional group in its molecular chain. The montmorillonite particles 11 have a flat plate portion charged with a negative charge and side portions charged with a positive charge, and the positive charge exists so as to surround the peripheral portion of the plate-shaped montmorillonite particle 11. On the other hand, since the polymer compound 12 has an anionic functional group in its molecular chain, negative charges are scattered along the molecular chain. Then, the side portions of the montmorillonite particles 11 are electrostatically bonded to the molecular chains of the polymer compound 12, and the plurality of montmorillonite particles 11 are bonded via the polymer compound 12, thereby forming a tabular bond of the montmorillonite particles. It forms object 2. At this time, the montmorillonite particles 11 are bonded to form a tabular bond. Therefore, the tabular combination of montmorillonite particles 2 is a combination of montmorillonite particles and has a tabular shape. Although FIG. 2 shows an example in which the montmorillonite particles 11 are continuous and bonded in only one direction, in reality, they are continuous and bonded in a two-dimensional direction. As described above, the bond 2 of flat plate-shaped montmorillonite particles spreads in the three-dimensional direction in the ground preparation filling material 1.

The filling material for ground preparation of the present invention contains at least sand particles, montmorillonite particles, a polymer compound having an anionic functional group in its molecular chain, and water.

The sand particles are not particularly limited, and may be, for example, sand, sand containing silt or gravel, crushed stone and slag, soil generated on site, or the like. Further, the particle size of the sand particles is not particularly limited, and preferably the particle size is mainly about 0.074 to 2.0 mm, and the maximum particle size is preferably 9.5 mm or less.

Montmorillonite particles are composed of a plurality of montmorillonite unit crystals stacked in layers. This montmorillonite unit crystal consists of a tetrahedral sheet in which tetrahedrons formed by silicon atoms and oxygen atoms are connected in a sheet shape, and an octahedral sheet in which octahedrons formed by aluminum atoms and hydroxyl groups are connected in a sheet shape. , has a sandwich structure in which one octahedral sheet is sandwiched between two tetrahedral sheets.

Montmorillonite particles have a tabular shape and a diameter of about 5 to 10 μm when saturated in water.

Montmorillonite unit crystals are the main component of bentonite, acid clay, etc. Bentonite is a type of tuff, and is a rock whose main component is montmorillonite, which has been chemically changed by undergoing thermal and stress changes over a long period of time. Bentonite is preferred as the raw material for the montmorillonite particles of the filling material for ground preparation of the present invention. As a raw material for the filling material for ground preparation of the present invention, bentonite that has been crushed into powder is suitably used.

The polymer compound having an anionic functional group in its molecular chain is not particularly limited as long as it has an anionic functional group in its molecular chain and can be electrostatically bonded to the sides of the montmorillonite particles. Examples of polymeric compounds having an anionic functional group in the molecular chain include homopolymers of acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylamide 2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, etc. Alternatively, examples include copolymers of acrylamide and one or more of acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylamide 2-methylpropanesulfonic acid, vinylsulfonic acid, and styrenesulfonic acid. For example, the polymer compound having an anionic functional group in its molecular chain includes a linear anionic polymer compound that is a copolymer of acrylic acid and acrylamide.

The molecular weight of the polymer compound having an anionic functional group in its molecular chain is not particularly limited, but is preferably 2 million or more and 10 million or less. The polymer compound having an anionic functional group in its molecular chain is in the form of a powder consisting of an acrylic polymer with an ionization degree of 0 to 100 mol% and a water-in-oil emulsion with a dispersed particle size of 100 μm or less. . The molecular weight of the polymer compound can be determined by the known method described in Japanese Patent Publication No. 34-10644.

The filling material for ground preparation of the present invention contains water. Water exists in the gaps between the tabular aggregates of montmorillonite grains, and is added to maintain the size of the gaps.

In the filling material for ground preparation of the present invention, the mass ratio of the polymer compound having an anionic functional group in the molecular chain to the montmorillonite particles (polymer compound/montmorillonite particles) is preferably from 0.020 to 0.50, and more preferably from 0.020 to 0.50. It is preferably 0.13 to 0.24, particularly preferably 0.17 to 0.19. By having the mass ratio of the polymer compound to the montmorillonite particles (polymer compound/montmorillonite particles) within the above range, a tabular combination of montmorillonite particles can be created, and a structure with a wide elastic range and stability in water can be obtained. I can do it.

In the filling material for ground preparation of the present invention, the mass ratio of montmorillonite particles to sand particles (montmorillonite particles/sand particles) is preferably 0.010 to 0.20, more preferably 0.050 to 0.090, particularly preferably is 0.060 to 0.080. By having the mass ratio of montmorillonite to sand particles (montmorillonite particles/sand particles) within the above range, the sand particles can be included in a laminated structure consisting of a tabular combination of montmorillonite particles, thereby ensuring inseparability. It becomes an integral filling material with

In the filling material for ground preparation of the present invention, the mass ratio of the polymer compound having an anionic functional group in the molecular chain to the sand particles (polymer compound/sand particles) is preferably 0.0050 to 0.020, or more. It is preferably 0.0070 to 0.018, particularly preferably 0.010 to 0.015. By setting the mass ratio of the polymer compound to the sand particles (polymer compound particles/sand particles) within the above range, the sand particles can be included in a laminated structure consisting of a tabular combination of montmorillonite particles, It becomes an integral filling material with inseparability.

In the filling material for ground preparation of the present invention, the mass ratio of montmorillonite particles to water (moisture in the filling material for ground preparation) (montmorillonite particles/water) is preferably 0.010 to 0.30, more preferably 0.010 to 0.30. 030 to 0.12, particularly preferably 0.070 to 0.10. When the mass ratio of montmorillonite particles to water (montmorillonite particles/water) is within the above range, the material has sufficient fluidity during installation of a pressure pump.

In the filling material for ground preparation of the present invention, the mass ratio of the polymer compound to water (moisture in the filling material for ground preparation) (polymer compound/water) is preferably 0.0050 to 0.025, more preferably It is 0.011 to 0.021, particularly preferably 0.013 to 0.019. When the mass ratio of the polymer compound to water (polymer compound/water) is within the above range, the material has sufficient flowability when a pressure pump is installed.

In addition to the above, the filling material for ground preparation of the present invention may appropriately contain other components used in filling materials for ground preparation. Other components that may be appropriately contained in the filling material for ground preparation of the present invention include, for example, dispersants such as polycarboxylate anionic surfactants.

The filling material for ground preparation of the present invention has a tabular bond of montmorillonite particles formed by bonding montmorillonite particles. The tabular combination of montmorillonite particles has a tabular shape and is connected in three dimensions. Note that connecting in a three-dimensional direction does not mean a structure in which flat plate-like objects spread in two-dimensional directions overlap in a layered manner, but rather that the sides of flat-like connected objects that spread in two-dimensional directions are connected in other two-dimensional directions. Refers to a structure that is connected to the flat part of a spreading flat plate-like compound.

Moreover, in the filling material for ground preparation of the present invention, the tabular combination of montmorillonite particles covers the sand particles. In the filling material for ground preparation of the present invention, the sand particles are covered by the tabular combination of montmorillonite particles that are spread in a three-dimensional direction, so that the sand particles are retained in the filling material for ground preparation of the present invention. has been done.

In the filling material for ground preparation of the present invention, the tabular combination of montmorillonite particles consists of montmorillonite particles and a polymer compound having an anionic functional group in its molecular chain. Then, due to the positive charges existing on the sides of the montmorillonite particles and the negative charges scattered in the molecular chains of the polymer compound having anionic functional groups in the molecular chains, the sides of the montmorillonite particles It is electrically bonded to the molecular chain of a polymer compound that has an anionic functional group inside. As a result, a plurality of montmorillonite particles are bonded via a polymer compound having an anionic functional group in its molecular chain, forming a tabular combination of montmorillonite particles.

The performance of the filling material for ground preparation of the present invention can be easily confirmed by a texture test. The texture test is a well-known test used in testing the physical properties of foods. After filling a specified container with a sample (filling material) at room temperature and setting it in a test device, when checking the "deformability", first move the cylinder up and down at a constant speed to penetrate and pull out 20 mm from the top of the sample. (first time), then, in the same way as the first time, move the cylinder up and down at a constant speed, penetrate and pull out 20 mm from the top surface of the sample (second time), find the change curve of the test force, and To check the damping properties, first move the cylinder up and down at a constant speed to penetrate and pull out 4mm from the top of the sample (first time), then repeat this 9 times to check the change in test force. demand. The "penetration stress" in the texture test is the penetration stress (Pa) obtained by converting the maximum load ha during penetration into stress. In addition, in the texture test, each physical property value can be automatically displayed without drawing a change curve for each test.

Generally, when a load is applied to a sample, the sample deforms or breaks. Regarding "deformability" in the texture test, a load is applied twice in succession, and the ratio of the applied area (energy) of the first and second times is defined as "deformability". Therefore, "deformability = 1" means that although it is deformed the first time, it restores to its original shape and has elastic properties that exhibit the same behavior the second time.
In addition, regarding the "damping property" in the texture test, the load was applied nine times in a row, and the ratio of the penetration stress (Pa) of each time to the penetration stress (Pa) of the first time (penetration stress 2nd time/penetration stress 1 3rd penetration stress/1st penetration stress, 4th penetration stress/1st penetration stress, 9th penetration stress/1st penetration stress), and their average value is defined as "damping property". Therefore, "damping property = 1" means that although it is deformed the first time, it restores to its original shape and exhibits the same behavior upon the ninth penetration.

The filler of the present invention has a deformability (A2/A1) in a texture test within 1 hour after production of 0.700 or more, preferably 0.700 to 1.400, more preferably 0.800 to 1.350. , particularly preferably 1.000 to 1.350, and the damping property is 0.700 or more, preferably 0.700 to 1.200, more preferably 0.800 to 1.200, particularly preferably 1 It is between .000 and 1.200.
For example, when such a filling material is dropped by gravity through a pipe into a cavity in the ground, it deforms and flows along the shape of the inside of the pipe, enters the cavity, and is filled along the shape of the inside of the cavity. Therefore, it is difficult for a gap to occur within the cavity. In addition, after filling, the soil maintains a suitable level of hardness, which stabilizes the strength of the ground. In addition, a low thixotropic product containing a small amount of bentonite has a deformability (A2/A1) of less than 0.700 in a texture test within 1 hour after production, and an attenuation property of less than 0.700.

The filling material for ground preparation of the present invention has a series elastic modulus E1 of 900 Pa or more, preferably 1,500 Pa or more, and a parallel elastic modulus E2 of 1,000 Pa or more, preferably 1,300 Pa or more. The filling material for ground preparation of the present invention has a parallel part viscosity η1 of 10,000 Pa·s or more, preferably 50,000 Pa·s or more, and a series part viscosity η2 of 200,000 Pa·s or more, preferably 500 Pa·s or more. ,000 Pa·s or more.
In the present invention, the elastic modulus E (Pa) and viscosity η (Pa・s) are measured using a viscoelasticity measurement device ARES-G2 manufactured by TA Instruments (JISK7132:1999 "Hard foam plastic compression creep under specified load and temperature conditions"). The compression creep compliance J(t) in the compression creep test according to ``4.3 Loading Apparatus'' is measured from the Burgers model approximation. The filling material for ground preparation of the present invention has high thixotropy, and has a modulus of elasticity E (Pa) and a viscosity η (Pa s) within the above ranges, so it has sufficient fluidity during pouring. If no pressure is applied, it will remain in place.

The filling material for ground preparation of the present invention has high stability against water, and is difficult to separate in water even if it is dropped directly into water. In the present invention, stability against water is confirmed by an underwater drop test. The underwater drop test is conducted as follows. At room temperature, pour 700 ml of tap water into a 1000 ml graduated cylinder, set a funnel with a minimum diameter of 40 mm in the opening, and drop 402.12 ml (X) of a lump of filler A1 through the funnel into the tap water by gravity. do. After dropping, the lumps fall through the water, settling and filling the bottom. After the filler is allowed to stand still, the volume (Y) of the lump is read and the filling property ((Y)/(X)) is measured. In addition, 300 ml of the supernatant is collected, and the color tone of the turbid water is visually observed, and the turbidity is measured using a turbidity meter (manufactured by Kyoritsu Physical and Chemical Research Institute, model number DPM2-TB500). The filling property ((Y)/(X)) is 1.00 to 1.20, preferably 1.00 to 1.10. The turbidity is 50 or less, preferably 20 or less. The filling material for ground preparation of the present invention has a filling property ((Y)/(X)) and a turbidity within the above range, so it has high stability against water, and even if dropped directly into water, it will remain stable in water. Difficult to separate.

The filling material for ground preparation of the present invention allows the filling materials to be bonded to each other, so it is possible to reduce voids during filling.

The method of manufacturing the filling material for ground preparation of the present invention is not particularly limited, and any manufacturing method may be used. An example of the method for producing the filling material for ground preparation of the present invention will be shown below, but the present invention is not limited to the method produced by this method.

The method for manufacturing the filling material for ground preparation of the present invention includes, for example, a first step of mixing and stirring sand particles, bentonite powder (montmorillonite particles), and water as necessary; A second step is to mix adjusted water in which a dispersant is dissolved into the mixture (1) obtained by performing the above steps and stir the mixture. A method for producing a filling material for ground preparation includes a third step of mixing and stirring a polymer compound solution in which a polymer compound having the following is dissolved.

Usually, sand particles are often in a wet state, and in the first step, sand particles in such a wet state can be used as the sand particles. In addition, in the first step, dry sand particles or wet sand particles can be mixed with water in advance to be appropriately moistened and used as the sand particles. In the first step, the sand particles moistened with water, bentonite powder, and water if necessary are mixed, and the bentonite powder is dispersed in the sand particles by stirring for 60 to 120 seconds, for example. . The mixing ratio of sand particles and bentonite powder is such that the mass ratio of bentonite powder to sand particles (excluding water) (bentonite powder/sand particles) is preferably 0.010 to 0.20, more preferably 0.050 to The mixing ratio is 0.090, particularly preferably 0.060 to 0.080.

The dispersant related to the second step is the same as the dispersant related to the filling material for ground preparation of the present invention. In the second step, the dispersant is dissolved in conditioned water in advance to prepare conditioned water in which the dispersant is dissolved, and the mixture (1) obtained by performing the first step is added to the conditioned water in which the dispersant is dissolved. and stirred for, for example, 60 to 240 seconds. The content of the dispersant in the conditioned water in which the dispersant is dissolved is selected as appropriate, but the content of the dispersant is preferably 0.1 to 1.5% by mass. In the second step, the amount of mixture (1) and the adjusted water in which the dispersant is dissolved is such that the mass ratio of bentonite powder to the adjusted water (excluding the dispersant) (bentonite powder/adjusted water) is preferably 0. The mixing amount is .010 to 0.30, more preferably 0.030 to 0.12, particularly preferably 0.070 to 0.10.

The polymer compound having an anionic functional group in its molecular chain according to the third step is the same as the polymer compound having an anionic functional group in its molecular chain according to the filling material for ground preparation of the present invention. The content of the polymer compound having an anionic functional group in its molecular chain in the polymer compound solution related to the third step is selected as appropriate, but is preferably 0.50 to 15.0% by mass. In the third step, a polymer compound solution is mixed with the mixture (2) obtained by performing the second step, and the mixture is stirred, for example, for 60 to 360 seconds. In the third step, the amount of polymer compound mixed is determined by dissolving the amount of water mixed in the first step (including the water contained in the sand particles before mixing) and the dispersant mixed in the second step. Mass ratio of the polymer compound to the total amount of water in the adjusted water and the amount of water in the polymer compound solution (polymer compound/total amount of water used in the first step, second step, and third step) However, the mixing amount is preferably 0.0050 to 0.025, more preferably 0.011 to 0.021, particularly preferably 0.013 to 0.019. The amount of the polymer compound to be mixed is such that the mass ratio of the polymer compound having an anionic functional group in the molecular chain to the bentonite powder (polymer compound/bentonite powder) is preferably 0.020 to 0.50, and more preferably 0.020 to 0.50. The mixing amount is preferably 0.13 to 0.24, particularly preferably 0.17 to 0.19. The amount of the polymer compound to be mixed is such that the mass ratio of the polymer compound having an anionic functional group in the molecular chain to the sand particles (polymer compound/sand particles) is preferably 0.0050 to 0.020, and more preferably 0.0050 to 0.020. The mixing amount is preferably 0.0070 to 0.018, particularly preferably 0.010 to 0.015.

Then, the filling material for ground preparation of the present invention can be obtained by carrying out the method for manufacturing the filling material for ground preparation of the present invention.

The filling material for ground preparation of the present invention may be prepared by an appropriate method and placed directly into the ground of the ground preparation target, or it may be obtained after mixing and stirring a cement solution. The mixture may be poured into the ground for ground preparation.

A cement solution is a powdered cement solidifying material dissolved in water. In the present invention, the mixing ratio of the cement solidification material and the sand particles in the filler material for ground preparation is not particularly limited and is appropriately selected, but is usually 50:1000 to 150:1000.

A solidifying agent can be added to the filling material when filling the filling material into a cavity existing in the ground, a gap between the ground and a structure, underwater ground, or a gap between the ground and a structure. When a solidifying agent is added to the filling material, it is necessary that the filling material does not have high strength. The filling material for ground preparation of the present invention can be solidified to a low strength by adding a small amount of solidifying agent. It is difficult to become.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

(Example 1)
(First step)
Bentonite powder (manufactured by Hojun ^Co. , Ltd., 70 g of dry sieve residue (10.0% or less (53 μm)) were mixed and stirred for 60 seconds to obtain a mixture (1).
(Second process)
Next, 5.0 g of a dispersant (polycarboxylate anionic surfactant) was dissolved in 492 g of water to prepare adjusted water in which the dispersant was dissolved. Next, the entire amount of adjusted water in which the dispersant was dissolved was mixed with the mixture (1) obtained above, and the mixture was stirred for 120 seconds to obtain a mixture (2).
(Third step)
Next, 12.8 g of a copolymer of acrylic acid and acrylamide (manufactured by Hymo Co., Ltd., trade name: SAVE-SP additive No. L1 for construction method) was dissolved in 200 g of water to prepare a polymer compound solution. Next, the entire amount of the polymer compound solution was mixed with the mixture (2) obtained above and stirred for 300 seconds to obtain a filling material for ground preparation.
Next, the obtained filling material for ground preparation was observed by SEM, and a SEM photograph was obtained. The results are shown in FIG. 3 (100 times) and FIG. 4 (200 times). In addition, we conducted measurements of viscoelastic modulus, texture test, underwater drop test, underground placement evaluation, and underwater stability evaluation. The results are shown in Table 1.

<Evaluation method>
(Scanning electron microscopy (SEM))
Samples were pretreated using a procedure of 1 flash freezing, 2 freeze drying, and 3 sectioning of dried samples.
Next, measurements were made using a scanning electron microscope (JSM-IT500HR, manufactured by JEOL Ltd.) under the conditions of signal SED, incident voltage 3.0 kV, WD 50.0 mm, and magnifications of 100 times and 200 times.

(Elastic modulus E (Pa) and viscosity η (Pa・s))
Compression creep compliance in a compression creep test using a viscoelasticity measuring device ARES-G2 manufactured by TA Instruments (based on JISK7132:1999 "Method for measuring compression creep under specified load and temperature conditions for hard foamed plastics" 4.3 loading device) The elastic modulus E (Pa) and viscosity η (Pa·s) were determined from the Burgers model approximation of t).

(Texture test “Deformability”)
Using a texture testing device (manufactured by Yamadensha, tabletop physical property measuring device), fill a specified container with a sample (filler) at room temperature, set it in the testing device, and then move the cylinder up and down at a constant speed. Then, the cylinder is moved up and down at a constant speed to penetrate and pull out 20 mm from the top surface of the sample (first time).Then, in the same way as the first time, the cylinder is moved up and down at a constant speed to penetrate and pull out 20 mm from the top surface of the sample (second time). (Pa), penetration energy (J/m ³ ), and deformability (A2/A1) were determined. Note that the deformability (A2/A1) refers to the ratio of the first and second load areas (energy).

(Texture test “attenuation”)
Using a texture testing device (manufactured by Yamadensha, tabletop physical property measuring device), fill a specified container with a sample (filler) at room temperature, set it in the testing device, and then move the cylinder up and down at a constant speed. Then, the cylinder is moved up and down at a constant speed to penetrate and pull out 4 mm from the top surface of the sample (first time).Then, in the same way as the first time, the cylinder is moved up and down at a constant speed to penetrate and pull out 4 mm from the top surface of the sample (second time). (Pa), penetration energy (J/m ³ ), and penetration stress ratio (second penetration stress/first penetration stress) were determined. This operation was repeated nine times. Next, the ratio of the penetration stress (Pa) of each time to the penetration stress (Pa) of the first time (penetration stress 2nd time / penetration stress 1st time, penetration stress 3rd time / penetration stress 1st time, penetration stress 4th time / penetration stress 1 (9th penetration stress/1st penetration stress) were determined, and their average value was defined as "damping property".

(Underwater drop test)
At room temperature, pour 700 ml of tap water into a 1000 ml graduated cylinder, set a funnel with a minimum diameter of (40 mm) in the opening, and pour 402.12 ml (X) of the lump of filler A1 through the funnel and into the tap water. Gravity dropped. After dropping, the lumps fell through the water, settling and filling the bottom. After the filler was allowed to stand still, the volume (Y) of the lump was read and the filling property ((Y)/(X)) was measured. In addition, 300 ml of the supernatant was collected, and the color tone of the turbid water was visually observed, and the turbidity was measured using a turbidity meter (manufactured by Kyoritsu Physical and Chemical Research Institute, model number DPM2-TB500).

<Performance evaluation>
(Evaluation of pouring performance in cavities)
The deformability in the texture test is above 0.700, the damping property in the texture test is 0.700 or more, the series elastic modulus E1 is 900 Pa or more, the parallel elastic modulus E2 is 1,000 or more Pa, In addition, when the parallel part viscosity η1 is 10,000 Pa·s or more and the series part viscosity η2 is 200,000 Pa·s or more, the casting performance in the cavity is evaluated as "Good", and the deformation in the texture test is evaluated. If any one of the elasticity, the damping property in the texture test, the series elastic modulus E1, and the parallel elastic modulus E2 does not satisfy the above range, the casting performance in the cavity was judged to be poor.
(Underwater stability evaluation)
When the supernatant turbidity in the underwater drop test was 50 or less, the underwater stability was evaluated as good "〇", and when the supernatant turbidity in the underwater drop test exceeded 50, the underwater stability was evaluated as poor "x".

(Examples 2-3, Comparative Examples 1-2)
The procedures were carried out in the same manner as in Example 1, except that the mixing amounts of each compounding material were as shown in Table 1. Stability evaluation was performed. The results are shown in Table 1.

1 Filling material for ground preparation 2 Tabular combination of montmorillonite particles 3 Sand particles 11 Montmorillonite unit crystal 12 High molecular compound having an anionic functional group in its molecular chain

Claims (7)

Containing at least sand particles, montmorillonite particles, a polymer compound having an anionic functional group in its molecular chain, and water,
The tabular combinations of montmorillonite particles are connected in a three-dimensional direction, and the sand particles are covered by the tabular combinations of montmorillonite particles to hold the sand particles;
The tabular bond of montmorillonite particles is formed by bonding the sides of the montmorillonite particles with the molecular chain of the polymer compound, thereby bonding a plurality of montmorillonite particles via the polymer compound. is being done,
A filling material for ground preparation characterized by: 2. The ground preparation method according to claim 1, wherein the polymer compound having an anionic functional group in its molecular chain is a linear anionic polymer compound which is a copolymer of acrylic acid and acrylamide. filling material. Claim 1 or 2, wherein a mass ratio of the polymer compound having an anionic functional group in the molecular chain to the montmorillonite particles (polymer compound/montmorillonite particles) is 0.020 to 0.50. Filling material for ground preparation as described. The filling material for ground preparation according to any one of claims 1 to 3, wherein a mass ratio of the montmorillonite particles to the sand particles (montmorillonite particles/sand particles) is 0.010 to 0.20. Claims 1 to 4, wherein a mass ratio of the polymer compound having an anionic functional group in the molecular chain to the sand particles (polymer compound/sand particles) is 0.0050 to 0.020. Filling material for ground preparation according to any one of the items. Claims 1 to 5, characterized in that a mass ratio of the montmorillonite particles to water in the filling material for ground preparation (montmorillonite particles/water in the filling material for ground preparation) is 0.010 to 0.30. Filling material for ground preparation according to any one of the items. The mass ratio of the polymer compound having an anionic functional group in the molecular chain to the water in the filling material for ground preparation (polymer compound/water in the filling material for ground preparation) is 0.0050 to 0.025. The filling material for ground preparation according to any one of claims 1 to 6, characterized in that:

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