Soil conditioner and soil improvement method

Abstract

The soil to be treated is assumed to be particularly water-containing soil such as construction sludge, which is difficult to solidify, and a soil conditioner is provided that improves the quality of the water-containing soil, thereby making it easier to handle, such as by transporting it. [Solution] A soil conditioner for modifying moist soil present in civil engineering or construction work, or soil improvement work, comprising a volume reduction agent that reduces the amount of inorganic preparation used on moist soil to reduce the volume of the modified soil, the volume reduction agent being a polymer preparation, the polymer preparation being at least one selected from the group consisting of hydrophilic polymers, water-absorbent polymers, and polymer flocculants, and the inorganic preparation comprising at least one selected from the group consisting of cement, quicklime, gypsum, paper sludge ash, and magnesium oxide.

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 difficulty of handling it as soil due to this water content reduces the efficiency of transporting construction sludge, etc. In order to increase the efficiency of transporting water-containing soil such as construction sludge, it is necessary to improve the soil (solidify or harden) using a soil conditioner.

[0003] Soil conditioners containing inorganic materials as the main component have been known for some time as soil conditioners for wet soil. For example, inorganic calcined powders containing volcanic ash clay, fly ash, silica fume, and paper sludge have been used as soil conditioners (see Patent Document 1).

[0004] According to Patent Document 1, simply adding a small amount of this soil conditioner to moist soil causes the components in the soil to solidify through a pozzolanic reaction, causing the moist soil to lose its fluidity and turn into sand. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-56980 Summary of the Invention [Problem to be solved by the invention]

[0006] However, as described in the examples of Patent Document 1, the test subjects add only cement to the wet soil, and the effects of adding both cement and a soil conditioner to the wet soil are examined. In other words, the soil conditioner in Patent Document 1 is intended to be used in combination with cement, and is not intended to improve (solidify) wet soil by itself. Since cement is also an inorganic material, and cement is considered a type of soil conditioner, Patent Document 1 uses a considerable amount of soil conditioner. Furthermore, the wet soil tested in Patent Document 1 is not an extremely difficult soil, such as the "soft soil requiring soil improvement" defined in the Ministry of Land, Infrastructure, Transport and Tourism's recycling guidelines. Therefore, the soil conditioner in Patent Document 1 cannot be said to have been designed to address the high-moisture soil encountered at actual construction sites, etc.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a soil conditioner and soil improvement method that modify the properties of wet soil, making it easier to handle, such as transport, by assuming that the soil to be treated is particularly wet soil that is difficult to solidify, such as construction sludge. [Means for solving the problem]

[0008] 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, The amount of inorganic preparation used for the water-containing soil is reduced, and the volume of the modified soil is reduced by containing a volume reducing agent.

[0009] The soil conditioner of this configuration is formulated to contain a volume-reducing agent that reduces the amount of inorganic preparation used compared to conventional soil conditioners that mainly contain inorganic preparations (inorganic materials), and therefore the amount of inorganic preparation used is reduced, thereby suppressing the increase in the volume and weight of the entire soil.As a result, soil improved with the soil conditioner of this configuration has a reduced volume compared to soil improved with conventional soil conditioners, making it easier to handle, such as transport.

[0010] In the soil improver according to the present invention, The volume reducing agent is preferably a polymeric preparation.

[0011] According to the soil conditioner of this configuration, by using a polymer preparation as a volume reduction agent, even if the soil to be improved is construction sludge or the like that contains a lot of water and is difficult to handle, when the soil conditioner of this configuration is mixed with the construction sludge or the like and stirred, the polymer preparation and the inorganic preparation work together to efficiently absorb the large amount of water contained in the construction sludge or the like into the soil conditioner or separate it from the soil, causing the soil to solidify and reduce in volume.

[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 water-containing soil is absorbed or separated from the soil by the polymer formulation. As a result, the water content of the soil after amendment is reduced, and the increase in the volume and weight of the entire soil can be suppressed.

[0014] In the soil improver according to the present invention, The inorganic preparation preferably contains at least one selected from the group consisting of cement, quicklime, gypsum, paper sludge ash, and magnesium oxide.

[0015] According to the soil conditioner of this configuration, the inorganic agent to be combined with the soil conditioner is at least one selected from the group consisting of cement, quicklime, gypsum, paper sludge ash, and magnesium oxide. When the soil conditioner is added to and mixed with moist soil, the soil conditioner absorbs or removes moisture from the moist soil, and crystalline nuclei of the inorganic agent, which serve as the starting point for solidification, are generated in the soil. The crystals then grow in the soil, and as the pozzolanic reaction, hydration reaction, or exothermic reaction progresses, the inorganic agent and the volume-reducing agent work together to solidify the entire soil.

[0016] In the soil improver according to the present invention, The amount of the volume reducing agent added to the water-containing soil is 0.5 to 10 kg / m 3 The amount of the inorganic preparation added is 50 to 500 kg / m 3 It is preferable that the blending amounts of the volume reducing agent and / or the inorganic preparation are set so that:

[0017] According to the soil conditioner of this configuration, if the blending amount of the volume reducing agent and / or inorganic preparation is set to satisfy the above conditions, the improved soil will have a strength equal to or greater than that of Class 4 improved soil as specified by the Ministry of Land, Infrastructure, Transport and Tourism (Cone index 200 kN / m 2 This will enable the transport of reduced volume soil.

[0018] In the soil improver according to the present invention, Cone index of 200 kN / m according to the cone index test in accordance with JIS A 1228 2 It is preferable to modify the water-containing soil so that the above-mentioned conditions are met.

[0019] According to the soil conditioner of this composition, the cone index of the soil after improvement is 200 kN / m 2 If the soil is above this level, it will be classified as Type 4 improved soil or higher as specified by the Ministry of Land, Infrastructure, Transport and Tourism, and the reduced volume soil can be transported.

[0020] In the soil improver according to the present invention, It is preferable to modify the above-mentioned water-containing soil so that the table flow value in a table flow test according to JIS R 5201, in which the drop speed is changed to 1 drop / second and the number of drops is changed to 50, is 110 mm x 110 mm or less.

[0021] With this soil conditioner, if the table flow value of the soil after improvement is 110 mm x 110 mm or less, the soil will be classified as Class 4 improved soil or higher as specified by the Ministry of Land, Infrastructure, Transport and Tourism, and the reduced volume soil can be transported, etc.

[0022] In the soil improver according to the present invention, It is preferable to modify the wet soil so that the slump value in a slump test using a slump cone (top inner diameter 100 mm × bottom inner diameter 200 mm × height 300 mm) conforming to JIS A 1101:2020 is 3.0 cm or less, or the mini-slump value in a mini-slump test using a mini-slump cone (top inner diameter 50 mm × bottom inner diameter 100 mm × height 150 mm) is 1.5 cm or less.

[0023] With this soil conditioner, if the slump value of the improved soil is 3.0 cm or less, or the mini-slump value is 1.5 cm or less, the soil will be classified as Class 4 improved soil or higher as specified by the Ministry of Land, Infrastructure, Transport and Tourism, and the reduced volume soil can be transported, etc.

[0024] 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: The method includes adding any one of the soil improvers to the moist soil, The water-containing soil to which the soil improver has been added is subjected to the following conditions immediately after or one day after the addition of the soil improver: (a) Cone index of 200 kN / m in the cone index test according to JIS A 1228 2 End (b) Table flow value in the table flow test according to JIS R 5201 is 110 mm x 110 mm or less (c) A slump value of 3.0 cm or less in a slump test using a slump cone (top inner diameter 100 mm x bottom inner diameter 200 mm x height 300 mm) conforming to JIS A 1101:2020, or a mini-slump value of 1.5 cm or less in a mini-slump test using a mini-slump cone (top inner diameter 50 mm x bottom inner diameter 100 mm x height 150 mm) The purpose is to satisfy the following.

[0025] This soil improvement method, unlike conventional soil improvement methods that use soil conditioners primarily composed of inorganic agents, adds a volume-reducing agent, which reduces the amount of inorganic agent used. This reduces the amount of inorganic agent used, thereby minimizing the increase in the overall soil volume and weight. As a result, soil improved using this soil improvement method is reduced in volume compared to soil improved using conventional soil improvement methods, making it easier to handle and transport. Furthermore, if the soil containing the soil conditioner meets the above-mentioned conditions immediately after or one day after the addition of the soil conditioner, the soil becomes Class 4 improved soil or higher, as defined by the Ministry of Land, Infrastructure, Transport and Tourism. This allows for the transportation of the reduced soil.

[0026] In the soil improvement method according to the present invention, The soil conditioner is configured to contain the inorganic formulation, The addition step is preferably carried out so that the volume reduction agent and the inorganic preparation are added to the moist soil simultaneously, or so that the volume reduction agent is added to the moist soil and then the inorganic preparation is added.

[0027] According to this soil improvement method, a volume-reducing agent and an inorganic preparation are added simultaneously to the moist soil, or the volume-reducing agent and the inorganic preparation are added in that order. The soil improvement agent first absorbs or separates water from the moist soil, fragmenting and shrinking the soil. Crystal nuclei of the inorganic preparation, which serve as the starting point for solidification, are then formed within the fragmented soil. Crystals then grow within the soil, and solidification of the fragmented soil is completed as the pozzolanic reaction, hydration reaction, or exothermic reaction progresses. Thus, according to this soil improvement method, the inorganic preparation and the volume-reducing agent work together to solidify the entire soil. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is an image diagram illustrating the mechanism by which water-containing soil is solidified by the soil conditioner of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention aims to improve the quality of water-containing soil present in civil engineering or construction work, or soil improvement work, thereby facilitating its handling, such as transportation. 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 other materials that are intended to be treated by this invention are wet soils containing water. Wet soils have a moisture content of 10 to 60% by weight (11 to 122% moisture content) and primarily contain 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). Specifically, these soils are "soft soils that require soil improvement" according to the Ministry of Land, Infrastructure, Transport and Tourism's recycling guidelines. However, soils containing relatively large particles such as gravel can also be treated by this invention.

[0031] Construction sludge, etc., generally has a high water content, making it difficult to handle, such as transport. Therefore, the present inventors recognized that it was necessary to improve the properties of construction sludge, etc., in order to make it easier to handle, such as transport, and so created a soil conditioner that is particularly suitable for improving the quality of construction sludge, etc., with a high water content.

[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 by civil engineering work, construction work, underground construction, tunnel excavation work, soil improvement work, etc., the soil conditioner of the present invention can be used at many construction sites and work sites.

[0033] <Soil conditioner> The soil conditioner of the present invention is formulated to contain at least a volume-reducing agent and, optionally, an inorganic preparation. Alternatively, it may be a combination of a volume-reducing agent and an inorganic preparation (whether one or two agents). First, the mechanism by which water-containing soil is solidified by the soil conditioner of the present invention will be described.

[0034] Figure 1 is an illustration of the mechanism by which the soil conditioner of the present invention solidifies moist soil. When a volume-reducing agent is added to moist soil (Figure 1(a)), the action of the volume-reducing agent (by absorbing or removing water from the moist soil) solidifies the moist soil to a certain extent (Figure 1(b)), and the soil fragments and shrinks (Figure 1(c)). Fragmentation will be described later in the description of the volume-reducing agent. Next, when an inorganic agent is added (Figure 1(d)), the inorganic agent penetrates into the fragmented soil and generates crystal nuclei (Figure 1(e)). After about one day, crystals grow in the fragmented soil (Figure 1(f)), and solidification is completed as the pozzolanic reaction, hydration reaction, or exothermic reaction progresses. Thus, the soil conditioner of the present invention solidifies moist soil through the cooperation of the volume-reducing agent and inorganic agent. The soil conditioner of the present invention allows for a reduction in the amount of inorganic agent used compared to conventional methods, thereby suppressing increases in the overall volume and weight of the soil. As a result, soil improved with the soil improver of the present invention has a reduced volume compared to soil improved with conventional soil improvers, making it easier to handle, such as transport.

[0035] The volume-reducing agent, which is the main component of the soil conditioner of the present invention, and the inorganic preparation that can be used in combination with the volume-reducing agent will be described below.

[0036] [Volume reducing agent] Volume-reducing agents are components that contribute to reducing the volume of improved soil by reducing the amount of inorganic preparation used for moist soil. Polymer preparations are preferred as volume-reducing agents, and polymer preparations with water affinity are particularly preferred. When a polymer preparation is added to moist soil and mixed, the moisture contained in the moist soil is absorbed by the polymer preparation, or the action of the polymer preparation causes the moisture contained in the moist soil to be released from the soil, reducing the moisture content of the moist soil and causing the soil to fragment (granulate) and shrink.

[0037] Examples of polymer preparations include hydrophilic polymers, water-absorbent polymers (SAPs), and polymer flocculants. Of these, hydrophilic polymers and water-absorbent polymers have the function of absorbing moisture (free water) present around soil particles. Polymer flocculants have the function of consolidating moisture (free water) present around the soil together with the soil (isolating it from the surroundings). The polymer preparation 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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 × 10 7 ~2.2×10 7 is more preferable. If the molecular weight of the polymer formulation is within the above range, the polymer formulation will have excellent ability to absorb or sequester water contained in wet soil, and will also be easy to handle as a volume reduction agent. The content of the polymer formulation in the volume reduction agent is not particularly limited and can be set arbitrarily within the range of 0.1 to 100% by weight.

[0045] The dosage form of the polymer preparation may be a powder or a liquid prepared by dissolving or dispersing it in a solvent such as water. In the case of a liquid polymer preparation, the solid content is preferably 10 to 80 wt %, more preferably 20 to 60 wt %, and even more preferably 40 to 50 wt %.

[0046] The amount of volume reducing agent to be added to wet soil is determined in relation to the amount of inorganic agent to be added, which will be described later, and should be between 0.5 and 10 kg / m 3 However, if the volume-reducing agent is a powdered polymer preparation, it is preferably 0.5 to 4 kg / m3 In the case of a liquid polymer preparation, it is preferably 1 to 10 kg / m 3 If the soil is in this range, the improved soil will have a strength equal to or greater than the fourth-class improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (cone index of 200 kN / m 2 This will enable the transport of reduced volume soil. [Inorganic preparations] The inorganic preparation is a component used to solidify moist soil. When the inorganic preparation is added to moist soil and mixed, as described above, crystalline nuclei of the inorganic preparation are formed in the moist soil, which act as the starting point for solidification. Then, through crystal growth, the components contained in the moist soil are solidified as the pozzolanic reaction, hydration reaction, or exothermic reaction progresses.

[0047] Inorganic preparations include cement, quicklime, gypsum, paper sludge ash, and magnesium oxide. Cement is primarily composed of calcium silicate and calcium aluminate and hardens through the pozzolanic reaction. Quicklime is primarily composed of calcium oxide and hardens through the pozzolanic reaction and exothermic reaction. Gypsum is primarily composed of calcium sulfate (gypsum hemihydrate) and hardens through a hydration reaction. Paper sludge ash is primarily composed of calcium oxide, silicon oxide, and cellulose and hardens through the pozzolanic reaction. Magnesium oxide hardens through a hydration reaction.

[0048] The amount of inorganic preparation to be added to the wet soil is determined in relation to the amount of volume reducing agent added, and is 50 to 500 kg / m 3 If the soil is in this range, the improved soil will have a strength equal to or greater than the fourth-class improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (cone index of 200 kN / m 2 This will enable the transport of reduced volume soil.

[0049] [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.

[0050] [Soil conditioner performance] The soil conditioner of the present invention can improve water-containing soil to have the following properties. (a) Cone index of 200 kN / m in the cone index test according to JIS A 1228 2 End (b) Table flow value in the table flow test according to JIS R 5201 is 110 mm x 110 mm or less (c) A slump value of 3.0 cm or less in a slump test using a slump cone (top inner diameter 100 mm x bottom inner diameter 200 mm x height 300 mm) conforming to JIS A 1101:2020, or a mini-slump value of 1.5 cm or less in a mini-slump test using a mini-slump cone (top inner diameter 50 mm x bottom inner diameter 100 mm x height 150 mm)

[0051] Soil having the above properties (a) to (c) corresponds to soil of Class 4 improved soil or higher as specified by the Ministry of Land, Infrastructure, Transport and Tourism. The improvement test of the wet soil will be explained in the examples below.

[0052] <Soil improvement method> The soil improvement method of the present invention uses the above-mentioned soil improver to modify moist soil present in civil engineering or construction work, or soil improvement work, and involves carrying out an addition step of adding the above-mentioned soil improver to the moist soil.

[0053] In the addition process, the volume reducing agent and inorganic preparation may be added simultaneously to the hydrous soil, or the volume reducing agent may be added to the hydrous soil and then the inorganic preparation may be added. In the image diagram illustrating the mechanism by which hydrous soil solidifies shown in Figure 1, the volume reducing agent is added first and then the inorganic preparation is added. However, even when the volume reducing agent and inorganic preparation are added simultaneously, the solidification rate of the volume reducing agent is greater than the crystallization rate of the inorganic preparation, so the soil solidification proceeds according to the mechanism shown in Figure 1.

[0054] When the above-mentioned addition step is carried out, the water-containing soil to which the soil improver has been added satisfies the following conditions immediately after the addition of the soil improver or one day after the addition: (a) Cone index of 200 kN / m in the cone index test according to JIS A 1228 2 End (b) Table flow value in the table flow test according to JIS R 5201 is 110 mm x 110 mm or less (c) A slump value of 3.0 cm or less in a slump test using a slump cone (top inner diameter 100 mm x bottom inner diameter 200 mm x height 300 mm) conforming to JIS A 1101:2020, or a mini-slump value of 1.5 cm or less in a mini-slump test using a mini-slump cone (top inner diameter 50 mm x bottom inner diameter 100 mm x height 150 mm) Solidification proceeds so as to satisfy the following.

[0055] The soil improvement method of the present invention adds a volume-reducing agent, which reduces the amount of inorganic preparations used compared to conventional soil improvement methods that use soil conditioners primarily composed of inorganic preparations (inorganic materials). This reduces the amount of inorganic preparation used, thereby minimizing the increase in the overall volume and weight of the soil. As a result, soil improved by the soil improvement method of the present invention is reduced in volume compared to soil improved by conventional soil improvement methods, making it easier to handle, such as transporting. Furthermore, if the moist soil to which the soil conditioner has been added satisfies the above-mentioned conditions (a) cone index, (b) table flow value, and (c) slump or mini-slump value immediately after or one day after the addition of the soil conditioner, it becomes a Class 4 improved soil or higher as defined by the Ministry of Land, Infrastructure, Transport and Tourism, making the reduced soil easier to transport.

[0056] Furthermore, by adding a volume-reducing agent and an inorganic preparation simultaneously to the moist soil, or by adding the volume-reducing agent and the inorganic preparation to the moist soil in that order, the soil conditioner first absorbs or separates water from the moist soil, fragmenting and shrinking the moist soil. Crystal nuclei of the inorganic preparation, which serve as the starting point for solidification, are then formed within the fragmented soil. Crystals then grow within the soil, and as the pozzolanic reaction, hydration reaction, or exothermic reaction progresses, solidification of the fragmented soil is completed. Thus, with this soil improvement method, the inorganic preparation and the volume-reducing agent work together to solidify the entire soil. [Example]

[0057] In order to confirm the performance of the soil conditioner of the present invention, various tests were carried out using simulated soils simulating (1) a highly hydrated organic clay layer and (2) soil contained in a highly hydrated clay layer. Examples are described below.

[0058] (1) High water content organic clay <Simulated soil> The high-moisture organic clay contained in the high-moisture organic clay layer is soil with a high moisture content (moisture ratio), containing organic matter, and low strength. In this example, in order to simulate high-moisture organic clay, a cone index of 200 kN / m was used in accordance with the "Standards for the Use of Generated Soil" notified by the Ministry of Land, Infrastructure, Transport and Tourism (No. 112 of the Ministry of Land, Infrastructure, Transport and Tourism, No. 309 of the Ministry of Land, Infrastructure, Transport and Tourism, dated August 10, 2006). 2 We reproduced organic clayey soil, which is muddy soil with a water content of about 80% or more.

[0059] Specifically, Kasaoka clay (clay from Kasaoka City, Okayama Prefecture) and black soil (surface soil from Kanuma City, Tochigi Prefecture) were mixed at a weight ratio of 5:5, then water was added to a moisture content of approximately 100% and stirred until no lumps remained. After two days of standing, the moisture content was measured. If it remained above 80%, it was used as a simulated soil simulating high-moisture organic clay. The properties of the simulated soil were 100% moisture content, 1.45 specific gravity, and 11 cm mini-slump. The moisture content was measured using a heat-drying moisture meter (model MF-50, manufactured by A&D Co., Ltd.). The specific gravity was calculated from the volume and weight of the simulated soil placed in a beaker (500 mL). The mini-slump value was measured using a mini-slump test using a mini-slump cone (50 mm inner diameter at the top, 100 mm inner diameter at the bottom, and 150 mm height).

[0060] <Soil conditioner> The ingredients (chemicals) used as soil conditioners are as follows: [Volume reducing agent] Powdered polymer preparation (main ingredient: acrylic acid compound, "TG Lock" manufactured by Technica Godo Co., Ltd.) (hereinafter referred to as "PAM") Liquid polymer formulation (main ingredient: acrylic acid compound, solid content: 40% by weight, "TG Lock L" manufactured by Technica Godo Co., Ltd.) (hereinafter referred to as "PAML") [Inorganic preparations] Cement: UBE Mitsubishi Cement Corporation's "Eustabiler 60" Quicklime manufactured by Kawai Lime Industry Co., Ltd. Gypsum (hemihydrate gypsum) manufactured by E Plus Co., Ltd. Paper sludge ash "Watoru" manufactured by Jaiwat Co., Ltd. Magnesium oxide "Green Lime NP" manufactured by Ube Material Industries, Ltd.

[0061] (1-0) Soil solidification test using only volume reducing agents First, as a reference example, a soil solidification test using only the volume reducing agent, which is the main component of the soil conditioner of the present invention, was conducted to confirm the extent to which simulated soil could be solidified using only the volume reducing agent. In this reference example, the amount of volume reducing agent (PAM or PAML) added to the simulated soil (high-water-content organic clay) was changed as shown in Table 1 below, and the mini-slump value, table flow value, and cone index were measured immediately after addition and one day after addition.

[0062] The mini-slump value was determined by a mini-slump test using a mini-slump cone (top inner diameter 50 mm x bottom inner diameter 100 mm x height 150 mm). The table flow value was determined according to JIS R 5201, but with the drop speed changed to 1 drop / second and the number of drops changed to 50. The cone index was determined by a cone index test in accordance with JIS A 1228. Note that if the fluidity of the simulated soil was too high to measure, it was recorded as "-". This also applies to subsequent tests. The test results are shown in Table 1 below.

[0063] [Table 1]

[0064] As shown in Table 1, when the amount of PAM or PAML added to the simulated soil was gradually increased, the mini-slump value and table flow value tended to improve. However, the cone index of either PAM or PAML alone did not reach the strength of Class 4 improved soil (cone index of 200 kN / m) specified by the Ministry of Land, Infrastructure, Transport and Tourism. 2 Therefore, in subsequent soil solidification tests using the combined use of inorganic preparations and volume-reducing agents, the state of solidification of the simulated soil was evaluated using the Cone Index.

[0065] (1-1) Soil solidification test using cement and volume reducing agent in combination The amounts of cement and volume reducing agent (PAM or PAML) added to the simulated soil were changed as shown in Table 2 below, and the cone index was measured immediately after addition and one day after addition. The test results are shown in Table 2 below.

[0066] [Table 2]

[0067] As shown in Table 2, when the amount of cement added to the simulated soil was kept constant, gradually increasing the amount of PAM or PAML added to the simulated soil tended to improve the cone index. One day after adding the PAM or PAML to the simulated soil, the strength of the simulated soil was improved to at least the level of Class 4 improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (cone index of 200 kN / m 2 In order to achieve this, cement alone must be 200 kg / m 3 However, if cement is used in combination with PAM or PAML, the amount of cement added is 100 kg / m 3 It has been shown that the strength of improved soil is equal to or greater than 400kN / m, and that it is possible to reduce the amount of cement added by at least 50%. 2 In order to achieve this, cement alone must be 200 kg / m 3 However, if cement is used in combination with PAM or PAML, the amount of cement added is 150 kg / m 3 Anything above that is fine.

[0068] (1-2) Soil solidification test using quicklime and volume reducing agent The amount of quicklime and volume reducing agent (PAM or PAML) added to the simulated soil was changed as shown in Table 3 below, and the corn index was measured immediately after addition and one day after addition. The test results are shown in Table 3 below.

[0069] [Table 3]

[0070] As shown in Table 3, when the amount of quicklime added to the simulated soil was kept constant, gradually increasing the amount of PAM or PAML added to the simulated soil tended to improve the cone index. One day after adding the PAM or PAML to the simulated soil, the strength of the simulated soil was improved to at least the level of Class 4 improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (cone index of 200 kN / m 2 In order to achieve this, quicklime alone needs 150kg / m 3 However, if quicklime is used in combination with PAM or PAML, the amount of quicklime added is 100 kg / m 3 It has been shown that the amount of quicklime added can be reduced by at least 30% if the soil strength is above 400kN / m. 2 In order to achieve this, quicklime alone must be used at a rate of 200 kg / m 3 However, if quicklime is used in combination with PAM or PAML, the amount of quicklime added is 150 kg / m 3 Anything above that is fine.

[0071] (1-3) Soil solidification test using gypsum and volume reducing agent in combination The amounts of gypsum and volume reducing agent (PAM or PAML) added to the simulated soil were changed as shown in Table 4 below, and the corn index was measured immediately after addition and one day after addition. The test results are shown in Table 4 below.

[0072] [Table 4]

[0073] As shown in Table 4, when the amount of gypsum added to the simulated soil was kept constant, gradually increasing the amount of PAM or PAML added to the simulated soil tended to improve the cone index. One day after adding the simulated soil, the strength of the simulated soil was improved to at least the level of Class 4 improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (cone index of 200 kN / m 2In order to achieve this, it is impossible to use gypsum alone, but when gypsum is used in combination with PAM or PAML, the amount of gypsum added is 200 kg / m 3 This indicates that it is possible to use gypsum, which cannot be used alone, on highly hydrated organic clay.

[0074] (1-4) Soil solidification test using paper sludge ash and volume reducing agent in combination The amounts of paper sludge ash and volume reducing agent (PAM or PAML) added to the simulated soil were changed as shown in Table 5 below, and the corn index was measured immediately after addition and one day after addition. The test results are shown in Table 5 below.

[0075] [Table 5]

[0076] As shown in Table 5, when the amount of paper sludge ash added to the simulated soil was kept constant, gradually increasing the amount of PAM or PAML added to the simulated soil tended to improve the cone index. One day after adding the simulated soil, the strength of the soil was improved to at least the level of Class 4 improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (cone index of 200 kN / m 2 In order to achieve this, paper sludge ash alone must be 200 kg / m 3 The above amount is required, but when paper sludge ash is used in combination with PAM or PAML, the amount of paper sludge ash to be added is 100 kg / m 3 It has been shown that the amount of paper sludge ash added can be reduced by at least 50% if the soil strength is above 400kN / m. 2 In order to achieve this, paper sludge ash alone must be 200 kg / m 3 However, if paper sludge ash is used in combination with PAM or PAML, the amount of paper sludge ash added is 150 kg / m 3 Anything above that is fine.

[0077] (1-5) Soil solidification test using magnesium oxide and volume reducing agent in combination The amounts of magnesium oxide and volume reducing agent (PAM or PAML) added to the simulated soil were changed as shown in Table 6 below, and the corn index was measured immediately after addition and one day after addition. The test results are shown in Table 6 below.

[0078] [Table 6]

[0079] As shown in Table 6, when the amount of magnesium oxide added to the simulated soil was kept constant, gradually increasing the amount of PAM or PAML added to the simulated soil tended to improve the cone index. One day after adding the simulated soil, the strength of the soil was improved to at least the level of Class 4 improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (cone index of 200 kN / m 2 In order to achieve this, magnesium oxide alone must be 200 kg / m 3 However, when magnesium oxide is used in combination with PAM or PAML, the amount of magnesium oxide added is 150 kg / m 3 This indicates that the amount of magnesium oxide added can be reduced by at least 25%.

[0080] (2) High water content clay <Simulated soil> The high-water content clay contained in the high-water content clay layer is soil with a high water content (water content ratio) and low strength. In this example, in order to simulate high-water content clay, a soil with a cone index of 200 kN / m was used in accordance with the "Standards for the Use of Generated Soil" notified 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 clayey soil, which is considered to be muddy soil with a water content of approximately 80% or more.

[0081] Specifically, Kasaoka clay (clay from Kasaoka City, Okayama Prefecture) and bentonite were mixed at a weight ratio of 9:1, then water was added to bring the moisture content to 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 high-moisture clay. The properties of the simulated soil actually prepared were a moisture content of 100% and a specific gravity of 1.44. The moisture content and specific gravity were measured using the same methods as those for high-moisture organic clay described above.

[0082] <Soil conditioner> The components (chemicals) used as the soil conditioner were the same as those used for the high-moisture organic clay described above.

[0083] (2-0) Soil solidification test using only volume reducing agents As in the reference example conducted on the high-water content organic clay described above, the amount of volume reducing agent (PAML) added to the simulated soil (high-water content clay) was varied as shown in Table 7 below, and the mini-slump value, table flow value, and cone index were measured immediately after addition and one day after addition. Note that for the high-water content organic clay described above, either PAM or PAML was used as the volume reducing agent, but similar trends (effects) were observed with both, so only PAML was used as the volume reducing agent for the high-water content clay. The test results are shown in Table 7 below.

[0084] [Table 7]

[0085] As shown in Table 7, when the amount of PAML added to the simulated soil was gradually increased, the mini-slump value and table flow value tended to improve. However, the cone index of the simulated soil was not improved by PAML alone, which was higher than the strength of the fourth-class improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (cone index of 200 kN / m 2 Therefore, in subsequent soil solidification tests using the combined use of inorganic preparations and volume-reducing agents, the state of solidification of the simulated soil was evaluated using the Cone Index.

[0086] (2-1) Soil solidification test using cement and volume reducing agent The amounts of cement and volume reducing agent (PAML) added to the simulated soil were changed as shown in Table 8 below, and the cone index was measured immediately after addition and one day after addition. The test results are shown in Table 8 below.

[0087] [Table 8]

[0088] As shown in Table 8, when the amount of cement added to the simulated soil was kept constant, gradually increasing the amount of PAML added to the simulated soil tended to improve the cone index. One day after adding PAML to the simulated soil, the strength of the simulated soil reached or exceeded the level of Class 4 improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (cone index of 200 kN / m 2 In order to achieve this, cement alone must be 75 kg / m 3 The above amount is required, but if cement is used in combination with PAML, the amount of cement added is 50 kg / m 3 It has been shown that the strength of improved soil is equal to or greater than 300kN / m2, and that it is possible to reduce the amount of cement added by at least 30%. 2 In order to achieve this, cement alone must be 100kg / m 3 The above amount is required, but if cement is used in combination with PAML, the amount of cement added is 75 kg / m 3 Anything above that is fine.

[0089] (2-2) Soil solidification test using quicklime and volume reducing agent The amount of quicklime and volume reducing agent (PAML) added to the simulated soil was changed as shown in Table 9 below, and the corn index was measured immediately after addition and one day after addition. The test results are shown in Table 9 below.

[0090] [Table 9]

[0091] As shown in Table 9, one day after adding the sieve to the simulated soil, the strength of the sieve was higher than that of the fourth-class improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (the cone index was 200 kN / m 2 In order to achieve this, quicklime alone must be used at a rate of 200 kg / m 3 The above amount is required, but if quicklime is used in combination with PAML, the amount of quicklime added is 75 kg / m 3 It has been shown that the amount of quicklime added can be reduced by at least 60% if the soil strength is above 3rd class improved soil (cone index 400kN / m 2 In order to achieve this, quicklime alone must be used at a rate of 300 kg / m 3 The above amount of addition is necessary, but if quicklime is used in combination with PAML, the amount of quicklime added is 150 kg / m 3 Anything above that is fine.

[0092] (2-3) Soil solidification test using gypsum and volume reducing agent in combination The amounts of gypsum and volume reducing agent (PAML) added to the simulated soil were changed as shown in Table 10 below, and the corn index was measured immediately after addition and one day after addition. The test results are shown in Table 10 below.

[0093] [Table 10]

[0094] As shown in Table 10, one day after adding the sieve to the simulated soil, the strength of the sieve was higher than that of the fourth-class improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (the cone index was 200 kN / m 2 In order to achieve this, gypsum alone must be able to withstand a temperature of 600 kg / m 3 However, if gypsum is used in combination with PAML, the amount of gypsum added is 300 kg / m 3 It has been shown that the amount of gypsum added can be reduced by at least 50% if the soil strength is above 400kN / m. 2In order to achieve this, it is impossible to use gypsum alone, but when gypsum is used in combination with PAML, the amount of gypsum added is 500 kg / m 3 Anything above that is fine.

[0095] (2-4) Soil solidification test using paper sludge ash and volume reducing agent in combination The amount of paper sludge ash and volume reducing agent (PAML) added to the simulated soil was changed as shown in Table 11 below, and the corn index was measured immediately after addition and one day after addition. The test results are shown in Table 11 below.

[0096] [Table 11]

[0097] As shown in Table 11, one day after adding the sieve to the simulated soil, the strength of the sieve was higher than that of the fourth-class improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (the cone index was 200 kN / m 2 In order to achieve this, paper sludge ash alone must be able to produce 600 kg / m 3 However, if paper sludge ash is used in combination with PAML, the amount of paper sludge ash to be added is 300 kg / m 3 It has been shown that the amount of paper sludge ash added can be reduced by at least 50% if the soil strength is above 400kN / m. 2 Although it is not possible to achieve this with paper sludge ash alone, when paper sludge ash is used in combination with PAML, the amount of paper sludge ash added is 400 kg / m 3 Anything above that is fine.

[0098] (2-5) Soil solidification test using magnesium oxide and volume reducing agent in combination The amounts of magnesium oxide and volume reducing agent (PAML) added to the simulated soil were changed as shown in Table 12 below, and the corn index was measured immediately after addition and one day after addition. The test results are shown in Table 12 below.

[0099] [Table 12]

[0100] As shown in Table 12, one day after adding the sieve to the simulated soil, the strength of the sieve was higher than that of the fourth-class improved soil specified by the Ministry of Land, Infrastructure, Transport and Tourism (the cone index was 200 kN / m 2 In order to achieve this, magnesium oxide alone must be able to provide a thermal conductivity of 500 kg / m 3 However, when magnesium oxide is used in combination with PAML, the amount of magnesium oxide added is 400 kg / m 3 It has been shown that the amount of magnesium oxide added can be reduced by at least 20% if the soil strength is above 400kN / m. 2 In order to achieve this, magnesium oxide alone must be able to provide a thermal conductivity of 600 kg / m 3 However, if magnesium oxide is used in combination with PAML, the amount of magnesium oxide added is 500 kg / m 3 Anything above that is fine.

[0101] (3) Summary As can be seen from the above examples, the soil conditioner of the present invention is formulated to contain a volume-reducing agent that is effective in reducing the amount of inorganic preparations used, and therefore the amount of inorganic preparations used is reduced, thereby suppressing the increase in the volume and weight of the entire soil. As a result, soil improved with the soil conditioner of the present invention is reduced in volume compared to soil improved with conventional soil conditioners, making it easier to handle, such as transporting. This can also contribute to reducing transportation costs and carbon dioxide emissions associated with transportation. [Industrial Applicability]

[0102] 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. The moisture content of the soil in civil engineering or construction work or soil improvement work is 80-122%. The soil is improved to a strength of at least Class 4 improved soil (cone index 200 kN / m) as specified by the Ministry of Land, Infrastructure, Transport and Tourism. ２ A soil conditioner for improving soil to exhibit the above properties, The inorganic preparation for solidifying the water-containing soil is used in combination with cement, quicklime, or paper sludge; The soil is broken down into smaller pieces and the amount of the inorganic preparation used for the soil is reduced to reduce the volume of the soil that has been modified, and the soil contains an anionic polymer flocculant, a cationic polymer flocculant, or an amphoteric polymer flocculant, the anionic polymer flocculant containing an acrylic acid compound as a main component, The amount of the volume reducing agent added to the water-containing soil is 0.5 to 10 kg / m ３ and the amount of the inorganic preparation added is 50 to 500 kg / m ３ The soil conditioner in which the amount of the volume reducing agent and / or the inorganic preparation is set so as to satisfy the above condition.

2. 2. The soil conditioner according to claim 1, wherein the water-containing soil is modified so that the table flow value measured in a table flow test according to JIS R 5201, in which the drop speed is changed to 1 drop / second and the number of drops is changed to 50 drops, is 110 mm x 110 mm or less.

3. 2. The soil conditioner according to claim 1, wherein the moist soil is modified so that the slump value in a slump test using a slump cone (upper inner diameter 100 mm x lower inner diameter 200 mm x height 300 mm) conforming to JIS A 1101:2020 is 3.0 cm or less, or the mini-slump value in a mini-slump test using a mini-slump cone (upper inner diameter 50 mm x lower inner diameter 100 mm x height 150 mm) is 1.5 cm or less.

4. The water-containing soil present in civil engineering or construction work, or soil improvement work, is improved to a strength of at least Class 4 improved soil (cone index 200 kN / m ２ A soil improvement method for improving soil to exhibit the above properties, The method includes adding the soil improver according to any one of claims 1 to 3 to the moist soil to break down and solidify the moist soil, The water-containing soil to which the soil improver has been added is subjected to the following conditions immediately after or one day after the addition of the soil improver: (a) A cone index of 200 kN / m according to a cone index test in accordance with JIS A 1228 ２ End (b) The table flow value in the table flow test according to JIS R 5201 is 110 mm x 110 mm or less. (c) A slump value of 3.0 cm or less in a slump test using a slump cone (upper inner diameter 100 mm x lower inner diameter 200 mm x height 300 mm) conforming to JIS A 1101:2020, or a mini-slump value of 1.5 cm or less in a mini-slump test using a mini-slump cone (upper inner diameter 50 mm x lower inner diameter 100 mm x height 150 mm). A soil improvement method that meets the above requirements.

5. The soil conditioner is configured to contain the inorganic formulation, The soil improvement method according to claim 4, wherein the adding step is carried out so that the volume reducing agent and the inorganic preparation are added to the moist soil simultaneously, or so that the volume reducing agent is added to the moist soil and then the inorganic preparation is added.

Images