Granular body, ground-improving material, and ground-improving method

Abstract

To provide a granular body which, when used as a material for a ground-improving material, can impart self-healing performance to a hardened product of the ground-improving material and can maintain the self-healing performance imparted to the hardened product of the ground-improving material over a long period of time.SOLUTION: A granular body according to the present invention comprises resin and an ion-releasing compound capable of releasing a cation or an anion, and in a test conducted in accordance with JIS A 1102:2014 "Test method for sieve analysis of aggregates", 85 mass% or more of the granular body remains on a 5-mm sieve.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to granules. The present invention also relates to a ground improvement material using the granules. The present invention also relates to a ground improvement method using the ground improvement material. [Background technology]

[0002] A known method of improving ground involves mixing cement and water to obtain a ground improvement material, which is then filled into the ground (see, for example, Patent Documents 1 and 2 below). For example, the ground improvement material is filled into the space between an underground structure and the ground, or into voids in the ground, and then hardens, increasing the strength of the ground. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-109927 [Patent Document 2] Japanese Patent Application Publication No. 4-001365 Summary of the Invention [Problem to be solved by the invention]

[0004] Hardened soil improvement materials placed in the ground gradually deteriorate due to contact with groundwater, etc., which can cause cracks in the hardened soil improvement materials. Furthermore, hardened soil improvement materials placed in the ground gradually deteriorate, which can cause minute voids to form between the hardened soil improvement materials and the ground.

[0005] Conventional hardened soil improvement materials do not have self-repair properties, so if cracks or tiny voids occur in or around the hardened soil improvement materials placed in the ground, reinforcement may be required again.

[0006] The object of the present invention is to provide granules that, when used as a material for a ground improvement material, can impart self-repairing properties to the hardened product of the ground improvement material and can maintain the self-repairing properties imparted to the hardened product for a long period of time. Another object of the present invention is to provide a ground improvement material using the granules. Furthermore, the present invention is also to provide a ground improvement method using the ground improvement material. [Means for solving the problem]

[0007] This specification discloses the following granules, ground improvement material, and ground improvement method.

[0008] Item 1. Granules containing resin and an ion-releasing compound capable of releasing cations or anions, in a test conforming to JIS A 1102:2014 "Sieving test for aggregates," in which 85% or more by mass remain on a 5 mm sieve.

[0009] Item 2. The granules according to Item 1, wherein the ion-releasing compound is capable of forming a poorly water-soluble salt.

[0010] Item 3. The granules according to Item 1 or 2, wherein the ion-releasing compound is sodium bicarbonate, sodium carbonate, calcium formate, calcium acetate, calcium lactate, or calcium chloride.

[0011] Item 4. The granules according to any one of Items 1 to 3, wherein the ion-releasing compound includes sodium bicarbonate or sodium carbonate.

[0012] Item 5. The granules according to any one of Items 1 to 4, wherein the ion-releasing compound is present at least inside the granules.

[0013] Item 6. Granules according to Item 5, wherein the ion-releasing compound present inside the granules is present in a dispersed state inside the granules.

[0014] Item 7. The granules according to any one of Items 1 to 6, wherein the resin is a cured product of a curable resin or a thermoplastic resin.

[0015] Item 8. A ground improvement material comprising cement, water, and the granules according to any one of items 1 to 7.

[0016] Item 9. A ground improvement method for improving the ground using the ground improvement material according to item 8. [Effects of the Invention]

[0017] The granules of the present invention contain a resin and an ion-releasing compound capable of releasing cations or anions. In a test conforming to JIS A 1102:2014 "Sieving Test of Aggregates," 85% or more of the granules of the present invention are retained on a 5 mm sieve by mass. Because the granules of the present invention have the above-described configuration, when used as a soil improvement material, they can impart self-repairing properties to the hardened soil improvement material, and the self-repairing properties imparted to the hardened soil improvement material can be maintained for a long period of time. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a granule according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a granule according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be described in detail below.

[0020] (grain) The granules according to the present invention contain a resin and an ion-releasing compound capable of releasing cations or anions. In a test conforming to JIS A 1102:2014 "Sieving test of aggregates," 85% or more of the granules according to the present invention are retained on a 5 mm sieve by mass. In this specification, "granules" is also referred to as "powdered granules."

[0021] The granules of the present invention have the above-mentioned configuration, so when the granules are used as a material for ground improvement material, self-repairing properties can be imparted to the hardened ground improvement material, and the self-repairing properties imparted to the hardened ground improvement material can be maintained for a long period of time.

[0022] Therefore, the granules according to the present invention are preferably used as a material for a ground improvement material. The granules according to the present invention are preferably used by being mixed with cement, and more preferably by being mixed with cement and water.

[0023] Since the granules according to the present invention contain the ion-releasing compound, the hardened product of the soil improvement material also contains the ion-releasing compound. When the hardened product of the soil improvement material comes into contact with water, such as groundwater, ions are eluted from the ion-releasing compound, generating salts (e.g., poorly water-soluble salts). Furthermore, the eluted ions diffuse through the water, such as groundwater, and migrate to minute voids, thereby forming poorly water-soluble salts in the minute voids. For example, when the ion-releasing compound is sodium bicarbonate or sodium carbonate, the sodium ions are replaced by calcium ions in the cement contained in the ground or the hardened product of the soil improvement material, causing calcium carbonate to precipitate and deposit in cracks and minute voids that occur in the hardened product of the soil improvement material and its surroundings. The deposited calcium carbonate then fills the cracks and minute voids. Therefore, even if cracks or minute voids occur in the hardened product of the soil improvement material placed in the ground or its surroundings, they are self-healing (self-repairing performance).

[0024] In a test conforming to JIS A 1102:2014 "Sieving Test for Aggregates," 85% or more of the granules according to the present invention are retained on a 5 mm sieve by mass. Because the size of the granules according to the present invention is relatively large, the effects of the ion-releasing compound eluting from the granules and the release of ions from the ion-releasing compound are sustained for a long period of time. Therefore, the self-repairing performance is maintained for a long period of time.

[0025] Therefore, by using the granules according to the present invention, the soil improvement effect can be maintained for a long period of time, and for example, the infiltration of groundwater into underground structures can be effectively suppressed.

[0026] Furthermore, because the granules of the present invention are relatively large, they are less likely to inhibit the cement hydration reaction. When preparing a ground improvement material using granules of the same mass, smaller granules will have a higher proportion of ion-releasing compound in contact with cement and water than larger granules. Therefore, with small granules, the ions released from the ion-releasing compound may inhibit the cement hydration reaction, potentially reducing the performance of the resulting hardened ground improvement material. In contrast, because the granules of the present invention are relatively large, they are less likely to inhibit the cement hydration reaction. It is known that the rapid hydration reaction of cement takes approximately 24 hours. However, by using the granules of the present invention, ions can be effectively released from the ion-releasing compound, for example, 24 hours or more after mixing with cement.

[0027] In a test conforming to JIS A 1102:2014 "Sieving Test for Aggregates," the granules preferably retain 90% or more by mass on a 5mm sieve, more preferably 95% or more by mass on a 5mm sieve, and even more preferably 99% or more by mass on a 5mm sieve. In this case, the self-repairing performance imparted to the hardened soil improvement material can be maintained for an even longer period of time. Furthermore, in a test conforming to JIS A 1102:2014 "Sieving Test for Aggregates," the granules may retain 100% or less by mass on a 5mm sieve, or less than 100% by mass on a 5mm sieve.

[0028] In a test conforming to JIS A 1102:2014 "Sieving test of aggregates," it is preferable that 85% or more of the granules pass through a 40 mm sieve by mass percentage.

[0029] The shape of the particles is not particularly limited, and may be spherical, approximately spherical, cylindrical, columnar, rectangular, or any other shape.

[0030] From the viewpoint of more effectively exerting the effects of the present invention, it is preferable that the ion-releasing compound is present at least inside the granules, and the ion-releasing compound may be present both inside the granules and on the outer surface of the granules.

[0031] The ion-releasing compound present inside the granules is preferably present in a dispersed state inside the granules, in which case ions are gradually released from the ion-releasing compound present inside the granules, so that the self-repairing performance imparted to the hardened product of the ground improvement material can be maintained for a longer period of time.

[0032] The density of the granules is preferably greater than the density of water. The density of the granules at 25°C is preferably 1.0 g / cm 3 more preferably 1.2 g / cm 3 If the density is equal to or greater than the lower limit (or exceeds the lower limit), the mixability with cement can be further improved. The density of the granules at 25°C is 3.0 g / cm 3 It may be less than 2.5 g / cm 3 It may be the following:

[0033] The present invention will be specifically described below with reference to the drawings. Note that in the drawings, for convenience of illustration, the size of each component may differ from the actual size.

[0034] FIG. 1 is a cross-sectional view schematically showing a granule according to a first embodiment of the present invention.

[0035] Granules 1 shown in Fig. 1 contain a resin 2 and an ion-releasing compound 3. Granules 1 are rectangular parallelepiped-shaped. The ion-releasing compound 3 exists inside granules 1. The ion-releasing compound 3 exists in a dispersed state inside granules 1.

[0036] FIG. 2 is a cross-sectional view schematically showing a granule according to a second embodiment of the present invention.

[0037] Granules 1A shown in Fig. 2 contain a resin 2 and an ion-releasing compound 3. Granules 1A are spherical. The ion-releasing compound 3 exists inside granules 1A. The ion-releasing compound 3 exists in a dispersed state inside granules 1A.

[0038] The components used in the granules according to the present invention will be described in detail below.

[0039] <Resin> The granules contain a resin, and the resin may be used alone or in combination of two or more kinds.

[0040] Examples of the resin include thermoplastic resins, cured products of curable resins, and ion exchange resins.

[0041] The resin may be a thermoplastic resin, a cured product of a curable resin, an ion exchange resin, a cured product of a thermoplastic resin and a curable resin, a thermoplastic resin and an ion exchange resin, a cured product of a curable resin and an ion exchange resin, or a cured product of a thermoplastic resin, a curable resin and an ion exchange resin.

[0042] Examples of the thermoplastic resin include polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polyurethane, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polymethyl methacrylate resin, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, etc. One type of the thermoplastic resin may be used alone, or two or more types may be used in combination.

[0043] Examples of the curable resin include a thermosetting resin, a photocurable resin, and a moisture-curable resin. The curable resin may be used alone or in combination of two or more.

[0044] Examples of the thermosetting resin include epoxy resin, phenol resin, (meth)acrylic resin, unsaturated polyester resin, vinyl ester resin, polyimide resin, urethane resin, polyurea resin, etc. The thermosetting resin may be used in combination with a thermosetting agent.

[0045] Examples of the photocurable resin include (meth)acrylic resin, (meth)acrylic urethane resin, epoxy resin, silicone resin, etc. The photocurable resin may be used in combination with a photopolymerization initiator.

[0046] Examples of the moisture-curable resin include moisture-curable urethane resins and hydrolyzable silyl group-containing resins.

[0047] Examples of the ion exchange resin include strongly acidic cation exchange resins such as cation exchange resins having sulfonic acid groups, and weakly acidic cation exchange resins such as cation exchange resins having methacrylic carboxylic acid groups and cation exchange resins having acrylic carboxylic acid groups.

[0048] The resin is preferably a cured product of a curable resin or a thermoplastic resin, and more preferably a cured product of a thermosetting resin or a thermoplastic resin, in which case the granules can be easily produced.

[0049] The content of the resin in 100% by mass of the granules is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less. When the content of the resin is equal to or more than the lower limit and equal to or less than the upper limit, the content of the ion-releasing compound in the granules can be kept within a suitable range, and the effects of the present invention can be more effectively exhibited.

[0050] The total content of the resin and the ion-releasing compound in 100% by mass of the granules is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 97.5% by mass or more, particularly preferably 99% by mass or more, and most preferably 100% by mass. When the total content is equal to or greater than the lower limit, the effects of the present invention can be more effectively exhibited. Note that, in 100% by mass of the granules, the total content of the resin and the ion-releasing compound may be 100% by mass or less, less than 100% by mass, 99% by mass or less, or 98% by mass or less.

[0051] <Ion-releasing compounds> The granules contain an ion-releasing compound. The ion-releasing compound may be used alone or in combination of two or more kinds.

[0052] The ion-releasing compound is a compound capable of releasing cations or anions. The ion-releasing compound may be a compound capable of releasing cations, a compound capable of releasing anions, a compound capable of releasing both cations and anions, or a mixture of a compound capable of releasing cations and a compound capable of releasing anions. The ion-releasing compound may be in a particulate form.

[0053] The ion-releasing compound is preferably capable of forming a poorly water-soluble salt, in which case the effects of the present invention can be more effectively exhibited.

[0054] The above-mentioned "poorly water-soluble salt" means a salt in which, when 1 g of the poorly water-soluble salt is placed in 100 g of water and kept at 20°C for 10 minutes, the mass of the poorly water-soluble salt that dissolves in water is 0.1 g or less.

[0055] The ion-releasing compound is preferably a compound capable of generating a poorly water-soluble salt upon contact with moisture. When the ion-releasing compound is a compound capable of releasing cations, it is preferable that the cations released from the ion-releasing compound chemically react with anions dissolved in moisture or the like to generate a poorly water-soluble salt. When the ion-releasing compound is a compound capable of releasing anions, it is preferable that the anions released from the ion-releasing compound chemically react with cations dissolved in moisture or the like to generate a poorly water-soluble salt. Furthermore, when the ion-releasing compound is a compound capable of releasing both cations and anions, or a mixture of a compound capable of releasing cations and a compound capable of releasing anions, it is preferable that the cations and anions released from the ion-releasing compound migrate to a medium such as moisture and generate a poorly water-soluble salt at the point where they meet.

[0056] Examples of the poorly water-soluble salt include calcium carbonate, barium carbonate, calcium phosphate, calcium sulfate, calcium silicate, and iron hydroxide.

[0057] The poorly water-soluble salt is preferably calcium carbonate, that is, the ion-releasing compound is preferably capable of generating calcium carbonate as the poorly water-soluble salt.

[0058] Examples of the ion-releasing compound include calcium sulfate, sodium chloride, calcium chloride, potassium chloride, calcium nitrite, sodium nitrite, potassium nitrite, calcium nitrate, sodium nitrate, sodium nitrate, potassium nitrate, sodium thiocyanate, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, ammonium hydrogencarbonate, sodium silicate, aluminum hydroxide, aluminum oxide, sodium aluminum dioxide, calcium aluminate, magnesium silicofluoride, boric acid, dipotassium hydrogenphosphate, zinc oxide, lead oxide, copper oxide, amines, maleic anhydride, oxycarboxylic acids, oxycarboxylic acid salts, keto acids, keto acid salts, aminocarboxylic acids, aminocarboxylic acid salts, polymeric organic acids, polymeric organic acid salts, water-soluble acrylic acid, water-soluble acrylate salts, tricalcium silicate, dicalcium silicate, calcium aluminate, calcium aluminoferrite, calcium hydroxide, calcium oxide, calcium formate, calcium acetate, calcium magnesium acetate, calcium stearate, calcium citrate, calcium malate, calcium benzoate, calcium oxalate, calcium lactate, calcium hydrogencarbonate, potassium hydrogencarbonate, and sodium hydrogencarbonate.

[0059] The ion-releasing compound is preferably sodium bicarbonate, sodium carbonate, calcium formate, calcium acetate, calcium lactate, or calcium chloride, and more preferably contains sodium bicarbonate or sodium carbonate. In this case, the effects of the present invention can be more effectively exhibited.

[0060] The ion-releasing compound may be spherical, may have a shape other than spherical, or may be flat, but is preferably spherical.

[0061] The average particle diameter of the ion-releasing compound is preferably 1.0 μm or more, more preferably 5.0 μm or more, even more preferably 10 μm or more, preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 300 μm or less. When the average particle diameter of the ion-releasing compound is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the effects of the present invention can be more effectively exhibited. When the average particle diameter of the ion-releasing compound is equal to or greater than the above-mentioned lower limit, the dispersibility in granules can be improved. Furthermore, when the average particle diameter of the ion-releasing compound is equal to or greater than the above-mentioned lower limit, the ion-releasing compound can be well coated with a coating agent described below, thereby improving the dispersibility in granules.

[0062] The average particle size of the ion-releasing compound refers to the number-average particle size. The average particle size of the ion-releasing compound is determined by observing 50 random ion-releasing compounds under an electron microscope or an optical microscope and calculating the average value. The particle size of the ion-releasing compound refers to the equivalent circle diameter of the cross section of the ion-releasing compound.

[0063] In the granules, the surface of the ion-releasing compound may be coated with a coating agent, in which case the timing and amount of cations or anions released from the ion-releasing compound can be controlled.

[0064] The ion-releasing compound coated with the coating agent is preferably capable of releasing cations or anions when moisture comes into contact with the granules or the hardened soil improvement material and diffuses and penetrates into the coating agent. The ion-releasing compound coated with the coating agent may be capable of releasing cations or anions from voids in the coating agent. The ion-releasing compound coated with the coating agent may be capable of diffusing into the coating agent and releasing cations or anions. In these cases, the timing and amount of cations or anions released from the ion-releasing compound can be more effectively controlled.

[0065] Examples of materials for the coating agent include resins. The coating agent preferably contains a resin. In this case, the dispersibility of the ion-releasing compound in the granules and the soil improvement material can be improved, and the timing and amount of cation or anion release can be well controlled. Furthermore, the surface of the ion-releasing compound can be uniformly coated with the coating agent.

[0066] Examples of the resin include a water-soluble resin, a thermoplastic resin, a thermosetting resin, a photocurable resin, and a moisture-curable resin. The resin may be used alone or in combination of two or more.

[0067] Examples of the water-soluble resin include polyvinyl alcohol, polylactic acid resin (PLA resin), poly(meth)acrylic acid, poly(meth)acrylamide, polyvinylpyrrolidone, polyethylene oxide, and methylcellulose.

[0068] Examples of the thermoplastic resin include polyolefin resin, polyvinyl chloride resin, polyamide resin, polycarbonate resin, polystyrene resin, polyester resin, acrylonitrile-butadiene-styrene resin (ABS resin), polyethylene terephthalate (PET), and polymethyl methacrylate (PMMA).

[0069] Examples of the polyolefin resin include polyethylene, polypropylene, polystyrene, polybutene, polyisobutylene, polybutadiene, ethylene-vinyl acetate copolymer, and ethylene-α-olefin copolymer.

[0070] Examples of the thermosetting resin include epoxy resin, phenol resin, (meth)acrylic resin, unsaturated polyester resin, vinyl ester resin, polyimide resin, urethane resin, polyurea resin, etc. The thermosetting resin may be used in combination with a thermosetting agent.

[0071] Examples of the photocurable resin include (meth)acrylic resin, (meth)acrylic urethane resin, epoxy resin, silicone resin, etc. The photocurable resin may be used in combination with a photopolymerization initiator.

[0072] Examples of the moisture-curable resin include moisture-curable urethane resins and hydrolyzable silyl group-containing resins.

[0073] The thickness of the coating agent (thickness of the coating layer formed by the coating agent) is not particularly limited. From the viewpoint of better controlling the timing and amount of release of cations or anions from the ion-releasing compound, the thickness of the coating agent is preferably 0.5 μm or more, more preferably 1 μm or more, and preferably 100 μm or less, more preferably 50 μm or less.

[0074] The content of the ion-releasing compound in 100% by mass of the granules is preferably 5% by mass or more, more preferably 20% by mass or more, and preferably 95% by mass or less, more preferably 85% by mass or less. When the content of the ion-releasing compound is equal to or more than the lower limit and equal to or less than the upper limit, the effects of the present invention can be more effectively exhibited.

[0075] <Other ingredients> The granules may contain other components different from both the resin and the ion-releasing compound. Examples of such other components include a surface modifier, a thixotropic agent, and an antioxidant. Only one of the other components may be used, or two or more of them may be used in combination.

[0076] (Soil improvement material) The soil improvement material according to the present invention contains cement, water, and the above-mentioned granules. The soil improvement material has fluidity.

[0077] Examples of the cement include portland cement, blast furnace cement, silica cement, and fly ash cement.

[0078] In 100% by mass of the soil improvement material, the content of the cement is preferably 10% by mass or more, more preferably 15% by mass or more, and preferably 70% by mass or less, more preferably 60% by mass or less.

[0079] The content of the water in 100% by mass of the soil improvement material is preferably 20% by mass or more, more preferably 25% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less.

[0080] The content of the granules in 100% by mass of the ground improvement material is preferably 1% by mass or more, more preferably 3% by mass or more, preferably 50% by mass or less, more preferably 40% by mass or less. When the content of the granules is above the lower limit and below the upper limit, the effects of the present invention can be more effectively exhibited. Furthermore, when the content of the granules is above the lower limit and below the upper limit, inhibition of the cement hydration reaction can be further suppressed.

[0081] The soil improvement material can be produced by mixing the cement, the water, and the granules.

[0082] The soil improvement material may contain other components in addition to the three components of cement, water, and granules, as needed. Examples of the other components include sand, fine aggregate, and coarse aggregate. Only one of the other components may be used, or two or more may be used in combination.

[0083] (Soil improvement method) The ground can be improved using the above soil improvement material. A soil improvement method according to the present invention is a method for improving the ground using the above soil improvement material.

[0084] In the above-mentioned ground improvement method, it is preferable that the ground improvement material is filled into the space between the underground structure and the ground or into voids in the ground. After filling the ground improvement material, the ground improvement material hardens to improve the ground and increase its strength.

[0085] When filling the soil improvement material, the type of soil improvement material may be different between the initial filling stage and the later filling stage. For example, a soil improvement material that does not contain the granules (a conventional soil improvement material) may be used in the initial filling stage, and a soil improvement material that contains the granules (the soil improvement material of the present invention) may be used in the later filling stage. By using a soil improvement material that does not contain the granules (a conventional soil improvement material) in the initial filling stage, the soil improvement material can be distributed throughout the spaces or voids.

[0086] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0087] Example 1 A total of 100 g of a two-component epoxy resin ("Infraguard CRJ" manufactured by Sekisui Chemical Co., Ltd.) consisting of 50 g of base resin and 50 g of curing agent was kneaded and mixed with 50 g of sodium bicarbonate. The resulting mixture was filled into a cylindrical silicone mold with an inner diameter of 20 mm and a length of 10 mm. The curable resin was then cured by curing for 3 days in an environment at a temperature of 23°C and a humidity of 50%. The resin was then demolded from the silicone mold to obtain cylindrical granules. Observation using an electron microscope revealed that the average particle diameter of the sodium bicarbonate in the resulting granules was 250 μm. Furthermore, sodium bicarbonate was dispersed at least within the interior of the resulting granules.

[0088] Example 2 Rectangular granules were obtained in the same manner as in Example 1, except that a silicon mold with inner dimensions of 25.4 mm × 12.7 mm × 12.7 mm was used. Furthermore, electron microscope observation revealed that the average particle size of sodium bicarbonate in the obtained granules was 250 μm. Furthermore, sodium bicarbonate was present in a dispersed state at least inside the obtained granules.

[0089] Example 3 Cylindrical granules were obtained in the same manner as in Example 1, except that calcium chloride was used instead of sodium bicarbonate. Furthermore, electron microscope observation revealed that the average particle size of calcium chloride in the obtained granules was 300 μm. Furthermore, calcium chloride was present in a dispersed state at least inside the obtained granules.

[0090] Example 4 Rectangular granules were obtained in the same manner as in Example 1, except that calcium chloride was used instead of sodium bicarbonate and a silicon mold with inner dimensions of 25.4 mm × 12.7 mm × 12.7 mm was used. Furthermore, electron microscope observation revealed that the average particle size of calcium chloride in the obtained granules was 300 μm. Furthermore, calcium chloride was present in a dispersed state at least inside the obtained granules.

[0091] Example 5 Polyethylene terephthalate resin (RAMAPET N1, manufactured by Indorama Ventures) was dried in an oven at 120°C for 6 hours. 100 g of the dried polyethylene terephthalate resin was mixed with 100 g of sodium carbonate. The resulting mixture was molded using an injection molding machine (Moldlock X-801, manufactured by Century Innovation) and a mold at a resin temperature of 270°C to obtain cylindrical granules measuring φ20 mm x 10 mm. Observation using an electron microscope revealed that the average particle diameter of the sodium carbonate in the resulting granules was 200 μm. Furthermore, sodium carbonate was dispersed at least within the granules.

[0092] Example 6 Granules were obtained in the same manner as in Example 5, except that calcium formate was used instead of sodium carbonate. Observation under an electron microscope revealed that the average particle size of calcium formate in the obtained granules was 180 μm. Furthermore, calcium formate was present in a dispersed state at least inside the obtained granules.

[0093] Example 7 Cylindrical granules with an inner diameter of 20 mm and a length of 10 mm were obtained in the same manner as in Example 1, except that calcium acetate was used instead of sodium bicarbonate. Furthermore, electron microscopic observation revealed that the average particle diameter of calcium acetate in the obtained granules was 200 μm. Furthermore, calcium acetate was present in a dispersed state at least inside the obtained granules.

[0094] Example 8 Cylindrical granules measuring 20 mm in inner diameter and 10 mm in length were obtained in the same manner as in Example 1, except that calcium lactate was used instead of sodium bicarbonate. Observation under an electron microscope revealed that the average particle size of calcium lactate in the obtained granules was 200 μm. Furthermore, calcium lactate was present in a dispersed state at least inside the obtained granules.

[0095] Example 9 100 g of polypropylene resin (Prime Polypro E111G, manufactured by Prime Polymer Co., Ltd.) was mixed with 100 g of sodium carbonate. The resulting mixed material was molded using an injection molding machine (Moldlock X-801, manufactured by Century Innovation Co., Ltd.) and a mold at a resin temperature of 210°C to obtain cylindrical granules measuring φ20 mm x 10 mm. Observation under an electron microscope revealed that the average particle diameter of the sodium carbonate in the resulting granules was 200 μm. Furthermore, sodium carbonate was dispersed at least within the interior of the resulting granules.

[0096] Example 10 100 g of polyethylene resin ("LDPE Petrothene #360" manufactured by Tosoh Corporation) was mixed with 100 g of sodium carbonate. The resulting mixed material was molded using an injection molding machine ("Moldlock X-801" manufactured by Century Innovation Co., Ltd.) and a mold at a resin temperature of 180°C to obtain cylindrical granules measuring φ20 mm x 10 mm. Observation using an electron microscope revealed that the average particle diameter of the sodium carbonate in the resulting granules was 200 μm. Furthermore, sodium carbonate was present and dispersed at least within the interior of the resulting granules.

[0097] Example 11 100 g of polyethylene resin ("LLDPE Nipolon-L M75" manufactured by Tosoh Corporation) was mixed with 100 g of calcium formate. The resulting mixture was molded using an injection molding machine ("Moldlock X-801" manufactured by Century Innovation Co., Ltd.) and a mold at a resin temperature of 180°C to obtain cylindrical granules measuring φ20 mm x 10 mm. Observation using an electron microscope revealed that the average particle diameter of calcium formate in the resulting granules was 180 μm. Furthermore, calcium formate was dispersed at least within the interior of the resulting granules.

[0098] (Comparative Example 1) The test described below was carried out using sodium carbonate itself.

[0099] (Comparative Example 2) The test described below was carried out using sodium bicarbonate itself.

[0100] (Comparative Example 3) The test described below was carried out using calcium chloride itself.

[0101] Comparative Example 4 The test described below was carried out using calcium formate itself.

[0102] (Comparative Example 5) The test described below was carried out using calcium acetate itself.

[0103] (Comparative Example 6) The test described below was carried out using calcium lactate itself.

[0104] (Comparative Example 7) One granule obtained in Example 9 was placed in liquid nitrogen for 3 minutes and then removed. Immediately after removal, the granule was pulverized by hammering. The resulting pulverized material was used to carry out the tests described below. 100% of the pulverized material passed through a 0.5 mm sieve by mass.

[0105] (evaluation) (1) Sieving test (mass percentage remaining on a 5 mm sieve) The obtained granules (Examples 1 to 11), ion-releasing compounds (Comparative Examples 1 to 6), and pulverized material (Comparative Example 7) were subjected to a test in accordance with JIS A 1102:2014 "Sieving test of aggregates," and the mass percentage remaining on a 5 mm sieve was determined.

[0106] (2) Elution test For Examples 1 to 11, one granule was placed in a 310 mL plastic container with a screw cap containing 300 mL of ion-exchanged water, and the granule was immersed in the ion-exchanged water and allowed to stand in an atmosphere of 23°C for 60 days, 120 days, or 280 days.

[0107] For Comparative Example 1, sodium carbonate having a mass equivalent to the amount of sodium carbonate in the granules obtained in Example 5, i.e., a mass equivalent to 50% of the mass of the granules obtained in Example 5, was placed in a 310 mL plastic container with a screw cap containing 300 mL of ion-exchanged water and allowed to stand in an atmosphere at 23°C for 60 days.

[0108] For Comparative Example 2, sodium hydrogen carbonate having a mass equivalent to that of the sodium hydrogen carbonate in the granules obtained in Example 1, i.e., a mass equivalent to 33% of the mass of the granules obtained in Example 1, was placed in a 310 mL plastic container with a screw cap containing 300 mL of ion-exchanged water and allowed to stand in an atmosphere at 23°C for 60 days.

[0109] For Comparative Example 3, calcium chloride having a mass equivalent to that of calcium chloride in the granules obtained in Example 3, i.e., a mass equivalent to 33% of the mass of the granules obtained in Example 3, was placed in a 310 mL plastic container with a screw cap containing 300 mL of ion-exchanged water and allowed to stand in an atmosphere at 23°C for 60 days.

[0110] For Comparative Example 4, calcium formate having a mass equivalent to that of the calcium formate in the granules obtained in Example 6, i.e., a mass equivalent to 50% of the mass of the granules obtained in Example 6, was placed in a 310 mL plastic container with a screw cap containing 300 mL of ion-exchanged water and allowed to stand in an atmosphere at 23°C for 60 days.

[0111] For Comparative Example 5, calcium acetate having a mass equivalent to that of the calcium acetate in the granules obtained in Example 7, i.e., a mass equivalent to 33% of the mass of the granules obtained in Example 7, was placed in a 310 mL plastic container with a screw cap containing 300 mL of ion-exchanged water and allowed to stand in an atmosphere at 23°C for 60 days.

[0112] For Comparative Example 6, calcium lactate having a mass equivalent to that of the calcium lactate in the granules obtained in Example 8, i.e., a mass equivalent to 33% of the mass of the granules obtained in Example 8, was placed in a 310 mL plastic container with a screw cap containing 300 mL of ion-exchanged water and allowed to stand in an atmosphere of 23°C for 60 days.

[0113] In Comparative Example 7, the pulverized material was placed in a 310 mL plastic container with a screw cap containing 300 mL of ion-exchanged water and allowed to stand in an atmosphere at 23° C. for 60 days.

[0114] The granules (Examples 1 to 11), ion-releasing compounds (Comparative Examples 1 to 6), or pulverized material (Comparative Example 7) were immersed in ion-exchanged water, and the ion concentrations in the ion-exchanged water were quantified 60, 120, and 280 days later using an ion meter concentration measurement electrode (HORIBA "Electrical Conductivity HORIBA Laqua Twin Series"). The ion elution rate was calculated using the following formula.

[0115] Ion elution rate (%) = A / B x 100 A: Measured ion concentration in ion-exchange water B: Calculated ion concentration when all of the ion sources contained in the granules (Examples 1 to 11), ion-releasing compounds (Comparative Examples 1 to 6), or pulverized material (Comparative Example 7) are dissolved as ions in ion-exchanged water.

[0116] Details and results are shown in the following Tables 1 to 3. In the tables, "-" indicates that the test was not performed.

[0117] [Table 1]

[0118] [Table 2]

[0119] [Table 3]

[0120] It can be seen that the elution of ions continues even after a long period of time has passed since the immersion in ion-exchanged water in the granules obtained in Examples 1 to 11. Therefore, it can be seen that when the granules obtained in Examples 1 to 11 are used as materials for soil improvement materials, they can impart self-repairing properties to the hardened soil improvement material, and can maintain the self-repairing properties imparted to the hardened soil improvement material for a long period of time. [Explanation of symbols]

[0121] 1,1A…Grain 2...Resin 3...Ion-releasing compounds

Claims

1. a resin and an ion-releasing compound capable of releasing cations or anions; Granules in which 85% or more by mass remain on a 5 mm sieve in a test conforming to JIS A 1102:2014 "Sieving test for aggregates."

2. The granules according to claim 1 , wherein the ion-releasing compound is capable of forming a poorly water-soluble salt.

3. 3. Granules according to claim 1 or 2, wherein the ion-releasing compound is sodium bicarbonate, sodium carbonate, calcium formate, calcium acetate, calcium lactate, or calcium chloride.

4. 3. Granules according to claim 1 or 2, wherein the ion-releasing compound comprises sodium bicarbonate or sodium carbonate.

5. 3. Granules according to claim 1 or 2, wherein the ion-releasing compound is present at least inside the granules.

6. 6. The granules according to claim 5, wherein the ion-releasing compound present inside the granules is present in a dispersed state inside the granules.

7. The granules according to claim 1 or 2, wherein the resin is a cured product of a curable resin or a thermoplastic resin.

8. A ground improvement material comprising cement, water, and the granules according to claim 1 or 2.

9. A ground improvement method for improving ground using the ground improvement material according to claim 8.

Images