Soil conditioning agent and soil conditioning method

Abstract

To provide a low-cost soil conditioning agent which facilitates the handling and treatment of soil after modification, especially construction sludge as soil.SOLUTION: The soil conditioning agent for modifying water-containing soil existing in civil engineering work, construction work or soil improvement work contains a polymer preparation having affinity with water and an inorganic porous preparation (excluding zeolite) for imparting water repellency. The polymer preparation is at least one selected from the group consisting of a hydrophilic polymer, a water-absorbing polymer, and a polymer flocculant. The inorganic porous agent is obsidian perlite.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a soil conditioner and a soil improvement method for improving the quality of water-containing soil present in civil engineering or construction work or soil improvement work. [Background technology]

[0002] Soil generated during civil engineering work, construction work, soil improvement work, etc. (hereinafter referred to as "construction sludge, etc.") often contains a large amount of water, and the adhesiveness (stickiness) of the soil caused by this water makes handling such as transportation and storage, as well as subsequent treatment, difficult. In order to make the handling and treatment of construction sludge, etc. easier, it is necessary to improve the soil using soil conditioners and reduce the adhesiveness of the soil.

[0003] However, while some conventional soil conditioners have been designed to improve the dewaterability of soil containing a large amount of water, such as dredged soil (see, for example, Patent Document 1), none have been specifically designed to reduce the adhesiveness of construction sludge and the like.

[0004] Although not intended for construction sludge, the present applicant has invented a soil conditioner that aims to improve the quality of soil generated as mixed waste or disaster waste (see Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-188620 [Patent Document 2] Patent No. 6765661 Summary of the Invention [Problem to be solved by the invention]

[0006] The soil conditioner of Patent Document 2 is an agent developed to separate foreign matter such as combustible and non-combustible materials contained in soil, and contains sodium acrylate and a porous substance. The sodium acrylate is blended for the purpose of absorbing moisture contained in the soil. The porous substance functions to reduce soil adhesion by dispersing soil particles after the sodium acrylate has absorbed moisture.

[0007] Thus, the soil conditioner of Patent Document 2 uses sodium acrylate and a porous substance in cooperation to reduce soil adhesion. When soil adhesion is reduced, soil particles are less likely to adhere to the mesh of a sieve when the soil is sieved, making it easier to separate the soil from foreign matter contained in the soil, such as combustible and non-combustible materials. Incidentally, Patent Document 2 uses zeolite as the porous substance. When zeolite is used as the porous substance, the high adsorption capacity of zeolite makes it possible to adsorb and remove harmful substances such as radioactive materials.

[0008] However, construction sludge and the like usually contain almost no harmful substances such as radioactive materials. Therefore, there is little need to use expensive porous materials such as zeolite as a soil conditioner material. Moreover, especially when construction sludge and the like are to be treated, if the soil conditioner contains zeolite, the high cation exchange capacity and adsorption capacity of zeolite may change the chemical properties of the soil after treatment, making it more difficult to handle and treat.

[0009] The present invention has been made in consideration of the above problems, and aims to provide a low-cost soil conditioner and soil improvement method that facilitates the handling and treatment of soil after improvement, particularly for construction sludge and the like. [Means for solving the problem]

[0010] The characteristic configuration of the soil improver according to the present invention for solving the above problems is as follows: A soil conditioner for improving the quality of water-containing soil present in civil engineering or construction work or soil improvement work, a polymer formulation having affinity for water; Inorganic porous preparations (excluding zeolites) that impart water repellency, The purpose is to include

[0011] This soil conditioner contains a water-compatible polymeric formulation and a water-repellent inorganic porous formulation (excluding zeolite). Even if the soil to be improved is difficult to handle, such as construction sludge, due to its high moisture content, when the soil conditioner is mixed with the construction sludge and stirred, the polymeric formulation and the inorganic porous formulation work together to improve the adhesive (sticky) construction sludge into a loose powder, preventing soil aggregation. As a result, the soil's adhesiveness is reduced. This improved soil retains its chemical properties and reduces adhesion to machinery, making it easier to handle during transportation, storage, and subsequent processing. Furthermore, the absence of expensive zeolite in the formulation reduces the production costs of the soil conditioner.

[0012] In the soil improver according to the present invention, The polymer preparation is preferably at least one selected from the group consisting of hydrophilic polymers, water-absorbent polymers, and polymer flocculants.

[0013] According to the soil conditioner of this configuration, by using at least one selected from the group consisting of hydrophilic polymers, water-absorbent polymers, and polymer flocculants as the polymer formulation, the water (especially free water) contained in the hydrated soil is separated from the soil by the polymer formulation. When the inorganic porous formulation adheres to the surface of the soil particles in this state, the water repellency derived from the inorganic porous formulation is imparted to the soil particles. As a result, soil aggregation is prevented, and soil adhesion can be significantly reduced.

[0014] In the soil improver according to the present invention, The inorganic porous preparation is preferably obsidian perlite.

[0015] According to the soil conditioner of this configuration, by using obsidian perlite as an inorganic porous agent, it is possible to impart excellent water repellency to soil particles whose moisture has been separated by the polymer agent, prevent aggregation, and reduce soil adhesion. Moreover, because obsidian perlite does not have the ion exchange or adsorption capacity of zeolite, it can modify construction sludge, etc. into a form (a loose state) that is easy to handle and process without changing the chemical properties of the construction sludge, etc. before modification.

[0016] In the soil improver according to the present invention, The inorganic porous preparation preferably has micropores with a pore diameter of 100 to 500 nm.

[0017] According to the soil conditioner of this configuration, when a porous material with micropores having a pore diameter of 100 to 500 nm is used as the inorganic porous formulation, the moisture remaining on the surface of the soil particles, which causes wetting, cannot sufficiently penetrate into the micropores of the inorganic porous formulation, and the inorganic porous formulation acts like dusting powder to repel water, thereby exhibiting water repellency to the soil particles. As a result, the adhesion of the soil can be reduced.

[0018] In the soil improver according to the present invention, The inorganic porous preparation preferably has a bulk density of 0.7 to 1.2.

[0019] According to the soil conditioner of this configuration, by using a porous material having a bulk specific gravity of 0.7 to 1.2 as the inorganic porous preparation, the weight fluctuation range of the soil after adding the soil conditioner is kept small, making it easier to handle and process the soil after amendment.

[0020] In the soil improver according to the present invention, It is preferable that the amount of the inorganic porous preparation is greater than the amount of the polymer preparation on a weight basis.

[0021] According to the soil conditioner of this configuration, by increasing the amount of inorganic porous preparation by weight compared to the amount of polymer preparation, the water repellency of soil particles is further increased, thereby further reducing the adhesion of soil.

[0022] In the soil improver according to the present invention, It is preferable not to change the chemical properties of the soil.

[0023] The soil conditioner of this composition does not change the chemical properties of the soil, i.e., it does not chemically react with the soil, and therefore construction sludge, etc. can be modified into a form (a loose state) that is easy to handle and process without changing the chemical properties of the construction sludge, etc. before modification.

[0024] In the soil improver according to the present invention, When added to the moist soil, it is preferred that 95% or more of the moist soil is granulated on a weight basis to a particle size that will pass through a sieve with 9.5 mm openings.

[0025] With this soil conditioner, more than 95% of the moist soil can be granulated to a particle size that can pass through a 9.5 mm mesh sieve, allowing it to be modified into a form (crumbly state) that is easy to handle and process.

[0026] The characteristic configuration of the soil improvement method according to the present invention for solving the above problems is as follows: A soil improvement method for improving the quality of water-containing soil present in civil engineering or construction work or soil improvement work, comprising: a preparation step of adding a predetermined amount of any one of the soil improvers described above to a sample of moist soil, and repeating the addition of the soil improver until the result of a table flow test in accordance with JIS R5201 is within 105 mm x 105 mm, thereby determining the amount of the soil improver to be added to the moist soil; a treatment step of adding the soil improver to the water-containing soil to be treated in the amount determined in the preparation step and stirring the soil; The purpose is to encompass the above.

[0027] According to this soil improvement method, the optimal amount of soil conditioner to be added to the wet soil is determined during the preparation process. Therefore, even if the soil to be improved is difficult to handle, such as construction sludge, due to its high moisture content, the soil improvement method adds the soil conditioner to the construction sludge in the amount determined during the preparation process. When the soil is stirred, the polymer formulation and the inorganic porous formulation work together to improve the adhesive (sticky) construction sludge to a loose state, preventing soil aggregation. As a result, the soil's adhesiveness is reduced. This improved soil retains its chemical properties and reduces adhesion to machinery, making it easier to handle during transportation, storage, and subsequent processing. Furthermore, the formulation does not contain expensive zeolite, reducing the construction cost of the soil improvement method. [Brief explanation of the drawings]

[0028] [Figure 1] Figure 1 is an illustration that explains the mechanism by which obsidian perlite acts on soil. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention improves the adhesive (sticky) construction sludge and the like present in civil engineering or construction work, or soil improvement work, thereby facilitating handling such as transportation and storage, and subsequent treatment. The soil conditioner and soil improvement method according to the present invention will be described below. However, the present invention is not limited to the configurations described in the following embodiments and examples.

[0030] <Hydrous soil> The construction sludge and the like that is the target of treatment in the present invention is wet soil. Wet soil has a moisture content of 10 to 60% by weight (11 to 122% moisture content) and is primarily composed of relatively small particles such as sand (average particle size of approximately 2 to 0.6 mm), silt (average particle size of approximately 0.6 to 0.004 mm), and clay (average particle size of approximately 0.004 mm or less). However, soil containing relatively large particles such as gravel can also be treated in the present invention.

[0031] Construction sludge, etc., has high viscosity, tends to adhere to machinery and equipment, and its high water content makes it difficult to sift through using a classification device. Therefore, the inventors recognized that in order to make construction sludge, etc. easier to handle and process, it is necessary to improve the properties of construction sludge, etc., without changing its chemical properties as soil, and have created a soil conditioner suitable for improving the quality of construction sludge, etc.

[0032] The soil conditioner of the present invention can suitably treat, for example, wet soil containing clay and silt and sand in a weight ratio of 2:8 to 8:2 as solid components and having a moisture content of 45 to 50% by weight (moisture content ratio of 82 to 100%). Since wet soil with such properties is contained in most construction sludge generated in civil engineering, construction, underground construction, tunnel excavation, etc., the soil conditioner of the present invention can be used at many construction sites.

[0033] <Soil conditioner> The soil conditioner of the present invention is designed not to change the chemical properties of the soil (i.e., not to chemically react with the soil), and includes a polymer formulation and an inorganic porous formulation. The polymer formulation and the inorganic porous formulation, which are the main components of the soil conditioner of the present invention, will be described below.

[0034] [High molecular weight preparations] Polymer formulations are components that contribute to reducing the moisture content of soil. They function by absorbing the moisture (free water) around soil particles or by consolidating the moisture (free water) around the soil with the soil (isolating it from the surrounding area), thereby preventing soil particles from gathering together and forming aggregates. Therefore, polymer formulations use polymeric materials that have an affinity for water.

[0035] Representative polymer formulations include hydrophilic polymers, water-absorbent polymers (SAPs), and polymer flocculants. Of these, hydrophilic polymers and water-absorbent polymers prevent soil aggregation by absorbing the water (free water) present around soil particles. Polymer flocculants prevent soil aggregation by consolidating the water (free water) present around the soil with the soil (isolating it from the surrounding area). The polymer formulation may contain a hydrophilic polymer, a water-absorbent polymer, or a polymer flocculant alone, or may be a mixture of two or more of these.

[0036] Examples of hydrophilic polymers include polyacrylic acid / polyacrylamide copolymers, polymethacrylic acid / polyacrylamide copolymers, polycarboxylic acid polymers, etc. Among these, a preferred hydrophilic polymer is polyacrylic acid / polyacrylamide copolymer.

[0037] Examples of water-absorbent polymers include polyacrylic acid polymers, polymethacrylic acid polymers, polyvinyl acetate polymers, polyvinyl alcohol polymers, carboxymethyl cellulose polymers, etc. Among these, a preferred water-absorbent polymer is sodium polyacrylate, which is a typical polyacrylic acid polymer.

[0038] As polymer flocculants, any of anionic polymer flocculants, cationic polymer flocculants, amphoteric polymer flocculants, and nonionic polymer flocculants can be used, but anionic polymer flocculants are preferred because of their excellent soil adhesion prevention properties and minimal environmental impact. Among amphoteric polymer flocculants, anionic-rich amphoteric polymer flocculants, which have more anionic groups than cationic groups, can also be used in the same way as anionic polymer flocculants. In other words, polymer flocculants containing anionic groups in their molecular structure (anionic polymer flocculants or anionic-rich amphoteric polymer flocculants) are preferably used.

[0039] Examples of anionic polymer flocculants include polycarboxylates or copolymers of polycarboxylates and acrylamide, polysulfonates or copolymers of polysulfonates and acrylamide, and derivatives thereof. Examples of polycarboxylic acids for forming polycarboxylates include acrylic acid, methacrylic acid, itaconic acid, and maleic acid. Examples of polysulfonic acids for forming polysulfonates include acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, and styrenesulfonic acid.

[0040] Examples of cationic polymer flocculants include alkylaminoacrylate salt polymers or copolymers of alkylaminoacrylate salt polymers and acrylamide, alkylaminomethacrylate salt polymers or copolymers of alkylaminomethacrylate salt polymers and acrylamide, and derivatives thereof. Examples of alkylaminoacrylate salt polymers include dimethylaminoethyl acrylate, dimethylaminopropyl acrylamide, acryloyloxyethyl trimethylammonium chloride, acryloylaminopropyl trimethylammonium chloride, and acryloyl 2-hydroxypropyl fluoride. Examples of alkylaminomethacrylate salt polymers include dimethylaminoethyl methacrylate, dimethylaminopropyl methacrylamide, methacryloyloxyethyl trimethylammonium chloride, methacryloylaminopropyl trimethylammonium chloride, and methacryloyl 2-hydroxypropyl fluoride.

[0041] Examples of amphoteric polymer flocculants include random copolymers, alternating copolymers, block copolymers, and graft copolymers of anionic monomers, which are constituent units of anionic polymer flocculants, cationic monomers, which are constituent units of cationic polymer flocculants, and nonionic monomers (if necessary). Random copolymers or alternating copolymers are preferred from the viewpoint of stability. The polymerization ratio of anionic monomers to cationic monomers is 30 to 45 mol%, preferably 35 to 42 mol%, of anionic groups, 0.1 to 10.0 mol%, preferably 0.1 to 4.0 mol%, of cationic groups, with the remainder being nonionic groups. In amphoteric polymer flocculants, the anionic groups of the anionic polymer flocculant and the cationic groups of the cationic polymer flocculant exist in the same polymer structure, but they do not undergo phase separation like a mixture of anionic and cationic polymer flocculants, and therefore can exhibit stable performance.

[0042] The molecular weight of the polymer formulation is 1.0 × 10 as the weight average molecular weight (Mw). 7 ~2.5×10 7 is preferred, and 1.3 × 107 ~2.2×10 7 is more preferable. If the molecular weight of the polymer formulation is within the above range, it will have excellent soil adhesion prevention properties and will be easy to handle as a soil conditioner. The content of the polymer formulation in the soil conditioner can be set arbitrarily within the range of 5 to 50% by weight, but it is preferably 10 to 30% by weight.

[0043] [Inorganic porous formulation] An inorganic porous formulation is a porous material with water-repellent properties. Numerous micropores are formed in the inorganic porous formulation. When the inorganic porous formulation adheres to soil particles, the moisture remaining on the surface of the soil particles, which causes wetting, cannot fully penetrate the micropores of the inorganic porous formulation, and the inorganic porous formulation acts like dusting powder, repelling water (this is called the "dusting powder effect"). This results in water-repellent properties in the soil particles. The size (pore diameter) of the micropores in the inorganic porous formulation is preferably 500 nm or less, more preferably 300 nm or less. It is also preferably 100 nm or more, more preferably 200 nm or more. By using a porous material with micropores with a pore diameter of 100 to 500 nm as the inorganic porous formulation, the dusting powder effect imparts good water-repellent properties to the soil particles, thereby reducing soil adhesion.

[0044] The bulk density of the inorganic porous preparation is preferably 0.7 or more, more preferably 1.0 or more. Also, it is preferably 1.2 or less, more preferably 1.1 or less. By using a porous material having a bulk density of 0.7 to 1.2 as the inorganic porous preparation, the weight fluctuation range of the soil after adding the soil conditioner is kept small, making it easier to handle the improved soil.

[0045] The particle size of the inorganic porous preparation is preferably 45 μm or more, more preferably 100 μm or more. Also, it is preferably 600 μm or less, more preferably 400 μm or less. By using a porous material having a particle size of 45 to 600 μm as the inorganic porous preparation, it becomes easy to adhere to the surface of soil particles, and can impart high water repellency to the soil particles.

[0046] A suitable inorganic porous preparation is obsidian perlite. Obsidian perlite is a porous mineral obtained by firing natural obsidian at high temperatures, and has micropores of 100 to 500 nm. These micropores contribute to the development of water repellency in obsidian perlite.

[0047] Figure 1 illustrates the mechanism by which obsidian perlite acts on soil. Figure 1(a) illustrates a diagram of hydrated soil. Hydrated soil is a state in which the soil is surrounded by water (free water). When a soil conditioner is added to hydrated soil and agitated, the polymer formulation contained in the soil conditioner absorbs the free water present around the soil, as shown in Figure 1(b). Meanwhile, the obsidian perlite contained in the soil conditioner adheres to the soil surface, as shown in Figure 1(c). Residual moisture, which causes wetting, remains on the surface of the soil particles, but the residual moisture cannot fully penetrate the micropores of the obsidian perlite. Therefore, the obsidian perlite acts like dusting powder and repels the residual moisture, resulting in water-repellent soil particles. Further agitation in this state results in the soil being pulverized and granulated, as shown in Figure 1(d). In this way, the obsidian perlite adheres to the surface of the soil particles that have absorbed water through the polymer formulation, imparting water-repellent properties to the soil. As a result, the soil becomes loose and prevents aggregation. Such soil modification does not change the chemical properties of the soil before modification, making it easier to handle during transportation, storage, and subsequent treatment.

[0048] Zeolite is known as an inorganic porous mineral. Zeolite is a porous substance with micropores of 0.3 to 1 nm. However, because zeolite has high cation exchange and adsorption capacities, when zeolite adheres to the surface of soil particles, it can change the chemical properties of the soil. Even in the case of construction sludge, if the chemical properties of the soil change, handling such as transportation and storage, and subsequent processing can become difficult. Furthermore, because zeolite is an expensive porous substance, it is not suitable for situations requiring low cost, such as construction sludge treatment. For these reasons, zeolite is not included in the inorganic porous formulation of the present invention. Obsidian perlite does not have the ion exchange or adsorption capacities of zeolite, and therefore does not change the chemical properties of construction sludge before modification.

[0049] [Combination of polymer preparation and inorganic porous preparation] The soil conditioner is prepared so that the amount of inorganic porous preparation is greater than the amount of polymer preparation on a weight basis. Specifically, the weight ratio of the polymer preparation to the inorganic porous preparation is preferably set to 1 / 99 to 49 / 51, more preferably 3 / 97 to 30 / 70. If the weight ratio of the polymer preparation to the inorganic porous preparation is set within the above range, the improvement of the water-containing soil (reduction of adhesion) can be further promoted, and soil that is easy to handle can be obtained.

[0050] [Other ingredients] Other ingredients can be added to the soil conditioner as needed. Examples of other ingredients include antifoaming agents, pH adjusters, solvents, thickeners, stabilizers, colorants, deodorizers, antibacterial agents, and antioxidants. These ingredients can be added alone or in combination.

[0051] <Soil improvement method> The soil improvement method of the present invention uses the above-mentioned soil improver to improve the quality of wet soil present in civil engineering or construction work, or soil improvement work, and is carried out by carrying out the following preparation steps and treatment steps.

[0052] [Preparation process] A soil conditioner is added in predetermined amounts to a sample of moist soil, and the addition of soil conditioner is repeated until the results of a table flow test in accordance with JIS R5201 are within 105 mm x 105 mm, thereby determining the amount of soil conditioner to be added to the moist soil. Details of the table flow test will be explained in the "Preparation" section of the Examples below.

[0053] [Processing process] The soil conditioner is added to the wet soil to be treated in the amount determined in the preparation step, and the soil is stirred.

[0054] According to the soil improvement method described above, the optimal amount of soil conditioner to be added to the wet soil is determined during the preparation process. Therefore, even if the soil to be improved is difficult to handle, such as construction sludge, due to its high moisture content, the soil improvement method can be carried out by adding the soil conditioner to the construction sludge in the amount determined during the preparation process and stirring the mixture. The polymer formulation and the inorganic porous formulation work together to improve the adhesive (sticky) construction sludge into a loose powder, preventing soil aggregation. As a result, the soil's adhesiveness is reduced. This improved soil retains its chemical properties and reduces adhesion to machinery and equipment, making it easier to handle during transportation, storage, and subsequent processing. Furthermore, the formulation does not contain expensive zeolite, reducing the construction cost of the soil improvement method. [Example]

[0055] In order to confirm the performance of the soil improver of the present invention, various tests were carried out using simulated soil. Examples are described below.

[0056] <Preparation of simulated soil> The water-containing soil that needs to be improved is soil with a high water content (water content ratio), organic matter, and low strength. In this example, in order to simulate water-containing soil, a soil with a cone index of 200 kN / m was used, as specified in the "Standards for the Use of Generated Soil" issued by the Ministry of Land, Infrastructure, Transport and Tourism (No. 112 of the Ministry of Land, Infrastructure, Transport and Tourism and No. 309 of the Ministry of Land, Infrastructure, Transport and Tourism, dated August 10, 2006).2 We reproduced organic soil, which is muddy soil with a water content of about 80% or more.

[0057] Specifically, Kasaoka clay (clay from Kasaoka City, Okayama Prefecture) and black soil (surface soil from Kanuma City, Tochigi Prefecture) were mixed in a 1:1 weight ratio, then water was added to a moisture content of approximately 100% and the mixture was stirred until no lumps remained. After leaving the mixture to stand for two days, the moisture content was measured, and if it remained above 80%, it was used as a simulated soil simulating wet soil. The properties of the simulated soil actually prepared were a moisture content of 100% and a pH of 7.2 (soil 1 w / v%). The moisture content and pH were measured using the following measuring device or method. [Water content ratio] Heat-drying moisture meter (model: MF-50, manufactured by A&D Co., Ltd.) [pH] 1 g of simulated soil was dispersed in 1 L of water, and the pH of the dispersion (1 w / v% soil) was measured using a pH meter (manufactured by AS ONE Corporation).

[0058] <Preparation of soil conditioner> The ingredients (chemicals) used to prepare the soil conditioner are as follows: [High molecular weight preparations] Water-absorbent polymer "SAP" manufactured by Technica Co., Ltd. Appearance: fine powder, particle size: 75-150 μm, water absorption ratio: 100-300 times Polymer flocculant: "Water Floc" manufactured by Technica Godo Co., Ltd. Appearance: fine powder, particle size: 75 μm or less [Inorganic porous formulation] Obsidian Perlite (manufactured by Pacific Perlite Co., Ltd.) Pore ​​size: 100~500nm, particle size: 45~600μm Perlite manufactured by Pacific Perlite Co., Ltd. Pore ​​size: several hundred nm to several tens of μm, particle size: 0.6 mm or less Vermiculite manufactured by Vermitech Co., Ltd. Pore ​​size: several μm or more, particle size: 75~150μm [Inorganic compounds] Calcium carbonate manufactured by Nitto Funka Kogyo Co., Ltd. Particle size: 150~425μm

[0059] The polymer preparation and the inorganic porous preparation were blended as shown in Table 1 below to prepare soil conditioners according to Examples 1 to 3 and Comparative Examples 1 to 6. Reference Examples 1 to 3 also comprise soil conditioners blended with the polymer preparation and calcium carbonate, an inorganic compound. The units of values ​​listed in Table 1 are parts by weight. Therefore, each example can be scaled up at any desired rate as long as the weight ratio of the polymer preparation to the inorganic porous preparation is maintained. In the following description, a soil conditioner using a water-absorbent polymer may be referred to as a water-absorbent soil conditioner, a soil conditioner using a polymer flocculant as a flocculant soil conditioner, and a soil conditioner using a water-absorbent polymer and a polymer flocculant as a mixed soil conditioner.

[0060] [Table 1]

[0061] <Advance preparation> The amount of soil conditioner to be added to the moist soil (simulated soil) varies depending on the type (mixture) of the soil conditioner. Therefore, as a preliminary step, the mixing conditions for the simulated soil and the amount of soil conditioner to be added to the simulated soil were determined using the following procedure. (1) Put 1 L of simulated soil into a bowl and add an appropriate amount of soil conditioner. (2) Mix the simulated soil in a stand mixer for 30 seconds, and after stopping, peel off some of the simulated soil that has adhered to the inside of the bowl and return it to the bowl. (3) Resume mixing with the stand mixer and stop mixing when there is no visible change in the appearance of the simulated soil to the naked eye. (4) After mixing is complete, a table flow test is conducted on the simulated soil (sample) in accordance with JIS R5201. (5) If the measured flow value is within 105mm x 105mm, use the amount added in (1) above. If the flow value exceeds 105mm x 105mm, increase the amount added in (1) above and repeat steps (2) to (5) above.

[0062] As a result of the above preliminary preparations, the mixing conditions for the simulated soil were determined as follows: after mixing for 30 seconds using a stand mixer, some of the simulated soil adhering to the inner surface of the bowl was peeled off and returned to the bowl, and then mixed for another 30 seconds.The amount of soil conditioner to be added to the simulated soil was determined as follows: Water-absorbing soil conditioner (Example 1, Comparative Example 1, Comparative Example 2, Reference Example 1): 25 kg / m 3 Aggregation-type soil conditioner (Example 2, Comparative Example 3, Comparative Example 4, Reference Example 2): 40 kg / m 3 Mixed soil conditioner (Example 3, Comparative Example 5, Comparative Example 6, Reference Example 3): 32.5 kg / m 3 (Water-absorbent soil conditioner 12.5 kg / m 3 + Coagulation soil conditioner 20kg / m 3 )

[0063] <Water content and pH measurement> Because the soil conditioner of the present invention does not use an inorganic porous preparation with high cation exchange capacity or adsorption capacity such as zeolite, its addition to moist soil (simulated soil) does not change the soil's chemical properties. To confirm this, the water content and pH of the simulated soil after amendment were measured using the following procedure and compared with the water content and pH of unamended simulated soil (control) without the addition of the soil conditioner. If the water content and pH of the simulated soil do not change significantly after amendment, it can be concluded that the chemical properties of the simulated soil have not changed. (1) Put 1 L of simulated soil into a bowl and add the soil conditioner in the amount determined in the "Preparation" section above. (2) Mix the simulated soil in a stand mixer for 30 seconds, and after stopping, peel off some of the simulated soil that has adhered to the inside of the bowl and return it to the bowl. (3) The simulated soil is stirred again for 30 seconds, and after stopping, the water content and pH (soil 1 wt%) of the simulated soil are measured in the same manner as described above in "Preparation of simulated soil." (4) As a control, the same procedure is carried out on the simulated soil in (1) above to which no soil conditioner has been added, and the water content and pH (1 wt% of soil) are measured. The measurement results are shown in Table 2 below.

[0064] [Table 2]

[0065] The simulated soils improved with the soil conditioners of Examples 1 to 3 maintained a water content of 95% or more compared to the unimproved simulated soil (control), and no significant changes in pH were observed. Therefore, it was confirmed that the soil conditioners containing obsidian perlite do not change the chemical properties of the simulated soil. The soil conditioners of Comparative Examples 1 to 6 and Reference Examples 1 to 3 can also be evaluated as not changing the chemical properties of the simulated soil. This is thought to be because perlite, vermiculite, and calcium carbonate, like obsidian perlite, are substances that lack cation exchange and adsorption capabilities.

[0066] <Evaluation of adhesion> In order to confirm whether the adhesion of the water-containing soil (simulated soil) improved using the soil conditioner of the present invention has been improved (whether it has become loose), the adhesion was evaluated using the following procedure. (1) Prepare a sieving device by stacking, from top to bottom, a lid, a first sieve with 9.5 mm openings, a second sieve with 4.75 mm openings, and a tray. (2) As a test specimen, 1 kg of the modified simulated soil used in the above "Measurement of water content and pH" is placed into a sieving device and sieved in accordance with the "Manual sieving" method described in JIS K0069:1992 (Sieving test method for chemical products) 3.3.1(1). (3) The transmittance (%) for each sieve is calculated from the weight of the test specimens remaining on the first and second sieves, and the adhesion is evaluated from the appearance of the test specimens remaining on each sieve. The results of the adhesion evaluation are shown in Table 3 below.

[0067] [Table 3]

[0068] The simulated soils amended with the soil conditioners of Examples 1 to 3 all had a sieve permeability of 95% or more through a 9.5 mm mesh and a sieve permeability of 65% or more through a 4.75 mm mesh, and the soils had a fine, loosely packed appearance. In particular, the simulated soil of Example 1, which was amended with the water-absorbing soil conditioner, had an exceptionally good sieve permeability of 4.75 mm mesh, and almost no soil adhesion to the sieving device was observed. Thus, it was shown that the simulated soils amended with the soil conditioners of Examples 1 to 3 were granulated to an appropriate size and were amended into an easy-to-handle form (loosely packed).

[0069] In contrast, the simulated soils amended with the soil conditioners of Comparative Examples 1 to 6 all had a sieve permeability of less than 95% with a mesh size of 9.5 mm, and although there were differences in the appearance of the soil, it was confirmed that the particles tended to become larger overall. In particular, the simulated soils amended with the soil conditioners of Comparative Examples 3 to 6 were confirmed to have become aggregated, and the soil adhered to the sieving device. The simulated soils amended with the soil conditioners of Reference Examples 1 to 3 had very poor sieve permeability, and the soil appeared wet, and the soil was confirmed to have become aggregated and adhered to the sieving device.

[0070] From the above results, it was confirmed that the combination of water-absorbent polymer and obsidian perlite is the most effective soil conditioner for improving construction sludge (wet soil) in terms of reducing adhesion.

[0071] <Strength evaluation> In order to make the handling and processing of the water-containing soil (simulated soil) improved with the soil improver of the present invention easier, it is necessary to maintain a certain level of soil strength while limiting the amount of soil additive added. Therefore, the soil strength was evaluated using the following procedure. (1) Lay a blue tarp on the concrete floor indoors. (2) As a test specimen, 1 L of the modified simulated soil used in the above "Measurement of water content and pH" was spread evenly on a blue sheet in an area of ​​40 cm x 40 cm. (3) Under conditions where natural ventilation is possible, adjust the room temperature to 18±3°C and the humidity to 45±10%, and leave the test specimen undisturbed for 24 hours. (4) After leaving the test specimen to stand, mix it and measure the water content. (5) For the test specimens whose moisture content has been measured, the cone index is measured in accordance with JIS A 1228, and the strength of the test specimens is evaluated in conjunction with the moisture content measurement results. The strength evaluation results are shown in Table 4 below.

[0072] [Table 4]

[0073] The simulated soils improved with the soil improvers of Examples 1 to 3 all had a cone index of 670 kN / m 2 As a result, it was evaluated that the soil had a certain level of strength. In addition, the simulated soils improved with the soil improvers of Examples 1 to 3 required a relatively small amount of soil improver added in volume terms, so the improved soil was not bulky and easy to handle. Therefore, even if the improved soil is reused, it is easy to handle and is not likely to deteriorate in workability.

[0074] In contrast, the simulated soils improved with the soil improvers of Comparative Examples 1 to 6, which used only the water-absorbing soil improver, achieved a certain level of soil strength, but the simulated soils improved with the soil improvers of Comparative Examples 3 to 6 had insufficient soil strength. The simulated soils improved with the soil improvers of Reference Examples 1 to 3 were difficult to handle and process due to their poor soil strength, and were not suitable for secondary use. In addition, the simulated soils improved with the soil improvers of Comparative Examples 1 to 6 had a large amount of soil improver added in terms of volume, so the improved soils were bulky and not easy to handle.

[0075] From the above results, it was confirmed that the combination of water-absorbent polymer and obsidian perlite is effective as a soil conditioner for improving construction sludge (wet soil), also in terms of strength development. [Industrial Applicability]

[0076] The soil conditioner and soil improvement method of the present invention can be used to improve construction sludge (wet soil) containing a large amount of water, which is generated during civil engineering work, construction work, and the like.

Claims

1. A soil conditioner for improving the quality of water-containing soil present in civil engineering or construction work or soil improvement work, a polymer formulation having affinity for water; Inorganic porous preparations (excluding zeolites) that impart water repellency; A soil conditioner containing

2. The soil conditioner according to claim 1, wherein the polymer preparation is at least one selected from the group consisting of hydrophilic polymers, water-absorbent polymers, and polymer flocculants.

3. The soil conditioner according to claim 1, wherein the inorganic porous preparation is obsidian perlite.

4. The soil conditioner according to claim 1, wherein the inorganic porous preparation has micropores with a pore diameter of 100 to 500 nm.

5. The soil conditioner according to claim 1, wherein the inorganic porous preparation has a bulk density of 0.7 to 1.

2.

6. 2. The soil conditioner according to claim 1, wherein the amount of the inorganic porous preparation is greater than the amount of the polymer preparation on a weight basis.

7. 2. The soil conditioner according to claim 1, which does not change the chemical properties of the soil.

8. 2. The soil conditioner according to claim 1, wherein when added to the moist soil, 95% or more of the moist soil is granulated to a particle size that passes through a sieve with 9.5 mm openings on a weight basis.

9. A soil improvement method for improving the quality of water-containing soil present in civil engineering or construction work or soil improvement work, comprising: A preparation step of adding a predetermined amount of the soil improver according to any one of claims 1 to 8 to a sample of moist soil, and repeating the addition of the soil improver until the result of a table flow test in accordance with JIS R5201 is within 105 mm x 105 mm, thereby determining the amount of the soil improver to be added to the moist soil; a treatment step of adding the soil improver to the water-containing soil to be treated in the amount determined in the preparation step and stirring the soil; A soil improvement method comprising the steps of:

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