Ground improvement agent

Abstract

We provide a ground improvement agent that reduces CO2 emissions while improving the ground. [Solution] Seawater is electrolyzed to extract an acid (S1, S3), and an acid is added to calcium waste material to produce a calcium agent with higher solubility in water than the calcium waste material (S4). A ground improvement agent containing the calcium agent and slag powder derived from metal smelting is then applied to the ground (S6).

Description

Technical Field

[0001] The present invention relates to a ground improvement agent.

Background Art

[0002] In order to improve the ground, blast furnace slag is blended with cement to reduce the amount of CO2 emissions derived from cement production. For example, Patent Document 1 discloses a cement slurry characterized by containing cement, blast furnace slag, salt, and water. When the total weight of cement and blast furnace slag is 100 parts by weight, the blast furnace slag is 80 parts by weight or less (excluding 0), and further, the salt is 20 parts by weight or less (excluding 0).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above technology, since cement is used for ground improvement, the amount of CO2 emissions derived from cement production is large. When cement is used for ground improvement, the amount of CO2 emissions increases, and there is a limit to CO2 reduction.

[0005] Therefore, the present invention has been made in view of the above problems and the like. An example of the problem is to provide a ground improvement agent that performs ground improvement while reducing CO2 as much as possible.

Means for Solving the Problems

[0006] To solve the above problems, the invention described in claim 1 is characterized by comprising: an acid extracting step of extracting an acid by electrolyzing seawater; a calcium agent manufacturing step of adding the acid to calcium waste material to produce a calcium agent with higher water solubility than the calcium waste material; and an application step of applying a ground improvement agent containing the calcium agent and slag powder derived from metal smelting to the ground.

[0007] Furthermore, the invention described in claim 2 further comprises an alkaline agent extraction step of extracting an alkaline agent that is produced together with the seawater in the electrolysis, characterized in that in the calcium agent production step, the alkaline agent is added to the calcium waste material after the acid agent has been added to produce the calcium agent.

[0008] Furthermore, the invention described in claim 3 comprises an alkaline agent extraction step of electrolyzing seawater to extract an alkaline agent, and an application step of applying a ground improvement agent containing the alkaline agent and slag powder derived from metal smelting to the ground, It is characterized by including.

[0009] Furthermore, the invention described in claim 4 is characterized by comprising: an alkaline agent extraction step of electrolyzing seawater to extract an alkaline agent; a calcium agent production step of adding an acid agent to calcium waste material, and then adding the alkaline agent to produce a calcium agent with higher water solubility than the calcium waste material; and an application step of applying a ground improvement agent containing the calcium agent and slag powder derived from metal smelting to the ground.

[0010] Furthermore, the invention described in claim 5 is characterized in that, in the application step, the ground improvement agent is mixed with seawater and applied to the ground.

[0011] Furthermore, the invention described in claim 6 is characterized in that the ground improvement agent includes the alkaline agent extracted by electrolysis.

[0012] Furthermore, the invention described in claim 7 is characterized in that the renewable energy is electrical energy generated by a wind turbine or solar power generator installed near the location where the seawater is collected.

[0013] Furthermore, the invention described in claim 8 is characterized by comprising: an acid extracting step of extracting an acid by electrolyzing seawater; a calcium agent manufacturing step of adding the acid to calcium waste material to produce a calcium agent with higher water solubility than the calcium waste material; and a ground improvement agent manufacturing step of producing a ground improvement agent containing the calcium agent and slag powder derived from metal smelting.

[0014] Furthermore, the invention described in claim 9 is characterized by comprising an alkaline agent extraction step of electrolyzing seawater to extract an alkaline agent, and a ground improvement agent manufacturing step of manufacturing a ground improvement agent containing the alkaline agent and slag powder derived from metal smelting.

[0015] Furthermore, the invention described in claim 10 is characterized by comprising: an alkaline agent extraction step of electrolyzing seawater to extract an alkaline agent; a calcium agent manufacturing step of adding an acid agent to calcium waste material, and then adding the alkaline agent to produce a calcium agent with higher water solubility than the calcium waste material; and a ground improvement agent manufacturing step of producing a ground improvement agent containing the calcium agent and slag powder derived from metal smelting.

[0016] Furthermore, the invention described in claim 11 is characterized by comprising a calcium agent powder derived from calcium waste material and having a higher solubility in water than the calcium waste material, and a slag powder derived from metal smelting. [Effects of the Invention]

[0017] According to the present invention, seawater is electrolyzed to extract an acid agent, the extracted acid agent is added to calcium waste material to produce a calcium agent that is more soluble in water than the calcium waste material, and a ground improvement agent containing the calcium agent and slag powder derived from metal smelting is applied to the ground. By using the acid agent extracted from seawater using renewable energy that does not generate CO2, the slag powder derived from metal smelting is hardened by the stimulation of the calcium agent extracted from the calcium waste material. Therefore, it is possible to improve the ground while reducing CO2 without using cement.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic diagram showing an example of the schematic configuration of a ground improvement system according to the first embodiment. [Figure 2] It is a flowchart showing an example of the procedure of a ground improvement method according to the first embodiment. [Figure 3] It is a schematic diagram showing an example of the concept of a ground improvement system according to the present embodiment. [Figure 4] It is a schematic diagram showing an example of the schematic configuration of a ground improvement system according to the second embodiment. [Figure 5] It is a flowchart showing an example of the procedure of a ground improvement method according to the second embodiment. [Figure 6] It is a schematic diagram showing an example of the schematic configuration of a ground improvement system according to the third embodiment. [Figure 7] It is a flowchart showing an example of the procedure of a ground improvement method according to the third embodiment. [Figure 8] It is a schematic diagram showing a modified example of the concept of a ground improvement system.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are embodiments when the present invention is applied to a ground improvement system or the like.

[0020] [1. Configuration and Functional Outline of Ground Improvement System]

[0021] First, the configuration and general functions of a ground improvement system according to one embodiment of the present invention will be explained using Figure 1.

[0022] Figure 1 is a schematic diagram showing an example of the general configuration of the ground improvement system according to this embodiment.

[0023] As shown in Figure 1, the ground improvement system 1 according to this embodiment includes an electrolysis device 10 that electrolyzes seawater using electricity from a power generation device G that generates electricity from renewable energy, an alkaline agent manufacturing device 11 that produces an alkaline agent from the components obtained by electrolyzing seawater with the electrolysis device 10, an acid agent manufacturing device 12 that produces an acid agent from the components obtained by electrolyzing seawater with the electrolysis device 10, a calcium agent manufacturing device 13 that produces a calcium agent from biologically derived calcium waste material, and a ground improvement agent adjusting device 14 that adjusts the ground improvement agent by mixing the calcium agent with powder of blast furnace granulated slag, which is an example of slag derived from metal smelting.

[0024] The power generation device G generates electricity using renewable energy sources such as wind, solar, tidal, wave, and geothermal energy, and supplies it to the electrolysis device 10. For example, the power generation device G may be a wind turbine that generates electricity using wind power, a solar power generator that generates electricity using solar power, or a combination of these. The power generation device G is preferably installed near where seawater is collected. Any power generation that does not emit greenhouse gases is acceptable, for example, nuclear power generation using a fission reactor or a fusion reactor.

[0025] The electrolysis apparatus 10 has a container for seawater, an anode, and a cathode. The anode and cathode are, for example, carbon rods. The anode and cathode are separated within the container by a semipermeable membrane or a ceramic separator. The electrolysis apparatus 10 has a seawater supply unit that supplies seawater to the anode and cathode sides of the container, a solution recovery unit that separately recovers the aqueous solutions from the anode and cathode sides, and a gas recovery unit that separately recovers the gases generated at the anode and cathode. The gas recovery unit may temporarily store each gas in a tank or supply it to the acid agent manufacturing apparatus 12 via a pipe.

[0026] The electrolysis apparatus 10 electrolyzes the sodium chloride contained in seawater drawn from the sea. Hydrogen is generated from the cathode of the electrolysis apparatus 10, and chlorine is generated from the anode. Sodium hydroxide is produced in the aqueous solution on the cathode side of the electrolysis apparatus 10. The electrolysis apparatus 10 is preferably installed near the source of seawater collection, and further preferably near the power generation apparatus G.

[0027] The alkali agent manufacturing apparatus 11 includes a container section for storing the aqueous solution on the cathode side of the electrolysis apparatus 10, and an alkali agent recovery section for recovering the manufactured alkali agent. The alkali agent manufacturing apparatus 11 extracts sodium hydroxide as an alkali agent from the aqueous solution on the cathode side of the electrolysis apparatus 10. The alkali agent manufacturing apparatus 11 concentrates or dries the aqueous solution taken from the cathode side of the electrolysis apparatus 10 for transport using renewable energy. The alkali agent manufacturing apparatus 11 may be equipped with a vacuum pump for reduced-pressure distillation. In order to obtain an alkali agent of high purity, an ion exchange membrane may be used. For example, a cation exchange membrane is used as a separator, and a saturated sodium chloride aqueous solution is supplied to the anode chamber, and a dilute sodium hydroxide solution is supplied to the cathode chamber. For example, carbon is used for the anode and iron for the cathode. When electricity is applied, the concentration of sodium hydroxide in the cathode chamber increases, and the concentration of the sodium chloride aqueous solution in the anode chamber decreases.

[0028] The acid agent manufacturing apparatus 12 has a receiving section that receives hydrogen gas and chlorine gas recovered in the electrolysis apparatus 10, a reaction section that reacts the hydrogen gas and chlorine gas to produce hydrogen chloride and dissolve it in water, and a recovery section that recovers hydrochloric acid. The acid agent manufacturing apparatus 12 produces hydrochloric acid as an acid agent from hydrogen generated from the cathode and chlorine generated from the anode of the electrolysis apparatus 10.

[0029] The calcium agent manufacturing apparatus 13 includes an acid agent receiving section for receiving hydrochloric acid produced by the acid agent manufacturing apparatus 12, an alkali agent receiving section for receiving sodium hydroxide produced by the alkali agent manufacturing apparatus 11, a calcium waste material receiving section for receiving calcium waste material, a first reaction section for reacting calcium waste material with hydrochloric acid, a second reaction section for reacting calcium chloride produced in the first reaction section with the alkali agent sodium hydroxide, a calcium agent recovery section for recovering calcium agents such as calcium chloride and calcium hydroxide, a gas recovery section for recovering CO2, and a sodium chloride recovery section for recovering sodium chloride produced in the second reaction section. The calcium waste material is biological calcium waste material containing calcium carbonate or calcium phosphate, such as seashells, livestock bones, or chicken manure. The calcium waste material may also be waste material derived from artificially created structures containing calcium carbonate, such as concrete rubble, from infrastructure structures and buildings.

[0030] The calcium agent manufacturing apparatus 13 adds biologically derived calcium waste material to the acid agent obtained in the acid agent manufacturing apparatus 12 and extracts a calcium agent with higher water solubility than the biologically derived calcium waste material.

[0031] The hydrochloric acid used as the acidifying agent reacts with the calcium carbonate in the calcium waste material to produce calcium chloride, generating CO2. If hypochlorous acid is used as the acidifying agent, calcium hypochlorite is produced. The calcium agent manufacturing apparatus 13 concentrates or dries the produced calcium chloride for transport using renewable energy. Any calcium compound with higher solubility in water than the calcium carbonate, calcium phosphate, etc., in the calcium waste material is acceptable as the calcium agent.

[0032] The generated CO2 is injected into rock layers deep underground. Alternatively, the CO2 may be compressed for transport and then transported to the location of the rock layer to be injected.

[0033] An electrolysis apparatus 10, an alkaline agent manufacturing apparatus 11, an acid agent manufacturing apparatus 12, and a calcium agent manufacturing apparatus 13 may form a plant for manufacturing alkaline agents and calcium agents, which are part of the raw materials for ground improvement agents. It is preferable that this plant and the power generation apparatus G be installed in a coastal area. The electricity to operate the plant is supplied from the power generation apparatus G.

[0034] The ground improvement agent adjustment device 14 has a receiving section that receives fine powder of blast furnace granulated slag from the steelworks and calcium agent from the calcium agent manufacturing device 13, a mixer section that mixes these, and a discharge section that discharges the adjusted ground improvement agent. Water or seawater, sand, soil, gravel, etc. may also be added to the mixer section. Since seawater contains calcium ions, calcium carbonate contained in the alkaline agent from the alkaline agent manufacturing device 11 may be added to the calcium agent manufacturing device 13, or calcium hydroxide contained in the alkaline agent may be added to the calcium agent from the calcium agent manufacturing device 13.

[0035] The ground improvement agent adjustment device 14 prepares the ground improvement agent by mixing fine powder of granulated blast furnace slag with a calcium agent that solidifies the granulated blast furnace slag. The pH concentration due to the calcium agent is adjusted with water to a concentration that makes it easy for the granulated blast furnace slag to harden, according to the target soil type. The ground improvement agent adjustment device 14 can be, for example, a batching plant or a mixer machine at the ground improvement site.

[0036] Here, granulated blast furnace slag is obtained by rapidly cooling molten blast furnace slag, a by-product of the ironmaking process using a blast furnace, with water, drying, and pulverizing it. Due to the rapid cooling, granulated blast furnace slag has nearly 100% glassy material (amorphous silica) and possesses latent hydraulic properties, meaning it hardens when exposed to stimulants such as alkalis. The fine powder of granulated blast furnace slag preferably has a maximum particle size of about 0.3 mm. However, fine aggregate of blast furnace slag with a particle size of several mm and a sandy texture is also acceptable, as is coarse aggregate of blast furnace slag with a particle size of pebbles.

[0037] Examples of slag derived from metal smelting include blast furnace granulated slag, as well as slag derived from the smelting of metals other than iron, such as copper, lead, zinc, and aluminum, and slag produced by methods other than blast furnaces. Slag from the smelting of non-metallic materials such as sulfur, graphite, and silicon is also acceptable. In addition to smelting that reduces ore to obtain metals, slag obtained from refining that extracts high-purity metals is also acceptable. Furthermore, in addition to slag, fly ash, silica fume, and pozzolanic materials derived from volcanic rock, which have latent hydraulic properties that harden when exposed to stimulants such as alkalis, are also acceptable.

[0038] The prepared ground improvement agent may be in the form of a water-free powder or a water-containing slurry. When producing a powdered ground improvement agent, the ground improvement agent preparation device 14 may be included in a plant consisting of an alkaline agent production device 11, an acid agent production device 12, and a calcium agent production device 13.

[0039] Furthermore, the ground improvement agent may contain aggregates such as soil, sand, gravel, and crushed stone. The ground improvement agent adjustment device 14 may also produce a slag solidification agent that does not contain granulated blast furnace slag, but contains an alkaline agent and a calcium agent. The slag solidification agent, granulated blast furnace slag, and aggregates are mixed at the site. The ground improvement agent does not necessarily have to contain a calcium agent. The proportions of granulated blast furnace slag, alkaline agents such as sodium hydroxide, and calcium agents such as calcium chloride may be changed depending on the condition of the ground to which the ground improvement agent is applied (for example, the target soil type). The proportions of granulated blast furnace slag and alkaline agents may be changed to adjust the strength of the solidified soil. The ground improvement agent adjustment device 14 adjusts the strength of the solidified soil according to the target soil type by devising the amounts of each raw material and the mixing procedure. Note that instead of seawater, only water may be used, or water may be mixed with components found in seawater, such as sodium chloride.

[0040] [2. Example of a ground improvement procedure] Next, an example of a ground improvement system procedure will be explained using Figures 2 and 3.

[0041] As shown in Figure 2, the ground improvement system 1 performs electrolysis of seawater using renewable energy (step S1). Specifically, as shown in Figure 3, the power generation device G generates electricity using renewable energy such as wind, solar, and geothermal energy. The electrolysis device 10 receives seawater pumped from the sea into the container section from the seawater supply section. The electrolysis device 10 receives electricity from the power generation device G and electrolyzes the pumped seawater.

[0042] The electrolysis apparatus 10 recovers hydrogen generated from the cathode and chlorine generated from the anode by electrolysis of an aqueous sodium chloride solution in a gas recovery unit. The electrolysis apparatus 10 supplies the generated hydrogen and chlorine to the acid agent manufacturing apparatus 12. Sodium hydroxide is generated in the aqueous solution on the cathode side of the electrolysis apparatus 10. The electrolysis apparatus 10 recovers the aqueous sodium hydroxide solution in a solution recovery unit. The electrolysis apparatus 10 supplies the generated aqueous sodium hydroxide solution to the alkaline agent manufacturing apparatus 11. Hypochlorous acid contained in the aqueous solution on the anode side of the electrolysis apparatus 10 may also be recovered.

[0043] Furthermore, the hydrogen generated from the cathode may be used as an energy source for hydrogen boilers, fuel cells, etc. Hydrogen boilers can be used to concentrate seawater, recover the steam generated during this concentration process to produce salt-free drinking water, or recover the water produced by the combustion of hydrogen to produce salt-free drinking water. Additionally, the chlorine generated from the anode may be used for water disinfection.

[0044] Next, the ground improvement system 1 manufactures an alkaline agent (step S2). Specifically, the alkaline agent manufacturing apparatus 11 receives the aqueous solution from the anode side of the electrolysis apparatus 10 into a container, and uses renewable energy to evaporate the water by vacuum distillation in the alkaline agent recovery section, thereby concentrating the aqueous solution containing sodium hydroxide or producing granular sodium hydroxide. Note that if the pH concentration due to sodium hydroxide, etc., is the concentration at which the blast furnace granulated slag hardens, concentration or drying is not necessary. To reduce transportation costs, the aqueous solution from the anode side of the electrolysis apparatus 10 may be concentrated or dried. Since seawater contains salts other than sodium chloride, the alkaline agent may contain components other than sodium hydroxide.

[0045] In this way, the electrolysis apparatus 10 and the alkaline agent manufacturing apparatus 11 manufacture an alkaline agent by electrolyzing seawater with electricity generated from renewable energy and extracting the alkaline agent.

[0046] Next, the ground improvement system 1 manufactures an acid agent (step S3). Specifically, the acid agent manufacturing apparatus 12 receives the hydrogen gas and chlorine gas recovered in the electrolysis apparatus 10 at the receiving section. The acid agent manufacturing apparatus 12 reacts the hydrogen generated from the cathode of the electrolysis apparatus 10 with the chlorine generated from the anode in the reaction section using a catalyst or the like to produce hydrogen chloride. The acid agent manufacturing apparatus 12 dissolves the hydrogen chloride in water to produce hydrochloric acid. Alternatively, the acid agent manufacturing apparatus 12 may recover hypochlorous acid contained in the aqueous solution on the anode side of the electrolysis apparatus 10 and use that as an acid agent.

[0047] Next, the ground improvement system 1 produces a calcium agent with high water solubility from biologically derived calcium waste materials (step S4). Specifically, the calcium agent production device 13 receives calcium waste materials from the calcium waste material receiving section into the first reaction section. The calcium agent production device 13 receives hydrochloric acid from the acid agent receiving section into the first reaction section. The calcium agent production device 13 adds hydrochloric acid to the calcium waste materials such as seashells and reacts them in the first reaction section. The calcium carbonate contained in the calcium waste materials reacts with the hydrochloric acid to produce calcium chloride and CO2. The calcium phosphate contained in the calcium waste materials produces calcium chloride and phosphoric acid. Chlorides of alkaline earth metals other than calcium, such as magnesium, may also be used.

[0048] Next, the calcium agent manufacturing apparatus 13 receives the calcium chloride produced in the first reaction section and the sodium hydroxide from the alkali agent receiving section into the second reaction section. The calcium agent manufacturing apparatus 13 adds the sodium hydroxide to the calcium chloride and reacts it in the second reaction section. The calcium chloride and sodium hydroxide react to produce sodium chloride and calcium hydroxide, which is the calcium agent.

[0049] As shown in Figure 3, by adding hydrochloric acid, an acid obtained by electrolyzing seawater, to biologically derived calcium waste, calcium chloride is produced. Then, by adding sodium hydroxide, an alkaline agent obtained by electrolysis, to the produced calcium chloride, calcium hydroxide is obtained, resulting in a calcium agent that has higher solubility in water and releases calcium ions more readily than biologically derived calcium waste. This calcium agent can also be used as calcium chloride. The acid added to the calcium waste may also be dilute sulfuric acid, which is used as a neutralizing agent.

[0050] The calcium agent manufacturing apparatus 13 recovers the generated CO2 in the gas recovery section. The recovered CO2 is stored in gas cylinders or the like and transported to a location where it will be injected into the rock mass.

[0051] The calcium agent manufacturing apparatus 13 collects the generated calcium hydroxide in the calcium agent recovery section. The recovered calcium agent is transported to the ground improvement agent adjustment apparatus 14.

[0052] In this manner, the calcium agent manufacturing apparatus 13 adds an acid obtained from seawater through electrolysis to biologically derived calcium waste material, extracts a calcium agent with higher water solubility than the biologically derived calcium waste material, and manufactures a calcium agent.

[0053] Next, the ground improvement system 1 prepares a ground improvement agent containing blast furnace slag powder and calcium agent (step S5). Specifically, the ground improvement agent preparation device 14 receives fine powder of blast furnace granulated slag from the steelworks and calcium agent from the calcium agent production device 13 in predetermined proportions from the receiving section. The ground improvement agent preparation device 14 may also accept water or seawater, sand, soil, gravel, etc.

[0054] As shown in Figure 3, a ground improvement agent is prepared by mixing blast furnace slag powder with calcium agents such as calcium hydroxide, which releases calcium ions.

[0055] Next, the ground improvement agent is mixed in the mixer section of the ground improvement agent adjustment device 14, and the adjusted ground improvement agent is discharged from the discharge section.

[0056] In this manner, the ground improvement agent preparation device 14 prepares a ground improvement agent containing calcium and blast furnace slag powder to produce the ground improvement agent.

[0057] Next, the ground improvement system 1 applies the ground improvement agent (step S6). Specifically, as shown in Figures 1 and 3, the ground improvement agent adjusted by the ground improvement agent adjustment device 14 is applied to the target ground. In the case of the columnar improvement method, holes are drilled in the ground and the adjusted slurry-like ground improvement agent is injected. In the case of the surface improvement method, the adjusted ground improvement agent is mixed with the ground surface to strengthen the surface layer of the ground. Alternatively, the ground improvement agent may be hardened as is to produce blocks for ground improvement.

[0058] In this way, a ground improvement agent containing calcium and blast furnace slag powder is applied to the ground.

[0059] According to the ground improvement system 1 of this embodiment, the power generation device G generates electricity using renewable energy, the electrolysis device 10 electrolyzes seawater, the acid agent manufacturing device 12 extracts an acid agent, the calcium agent manufacturing device 13 adds the extracted acid agent to calcium waste material to produce a calcium agent with higher water solubility than the calcium waste material, and the ground improvement agent adjustment device 14 adjusts the ground improvement agent containing the calcium agent and blast furnace slag powder. By applying this ground improvement agent to the ground, the slag powder derived from metal smelting hardens due to the stimulation of the calcium agent produced from calcium waste material by the acid agent extracted from seawater using renewable energy that does not generate CO2. Therefore, the ground can be improved without using cement and CO2 is reduced. Thus, low-carbon ground improvement becomes possible.

[0060] This invention relates to a cement-free solidification and improvement technology. The ground improvement agent adjustment device 14 can adjust the strength of the solidified and improved soil according to the target soil type by devising the amount and mixing procedure of each raw material, such as blast furnace slag powder and calcium agent. This enables ground improvement that suppresses the generation of greenhouse gases and improves upon the problem of high CO2 emissions associated with cement-based solidification and improvement.

[0061] By adding an acidifying agent such as hydrochloric acid, obtained from seawater through electrolysis, to biologically derived calcium waste, calcium agents such as calcium chloride, which have higher water solubility than the biologically derived calcium waste, can be extracted. When a ground improvement agent contains calcium agents, the calcium ions from the calcium agents further promote the solidification of the ground improvement agent. In addition, biologically derived calcium waste can be effectively utilized.

[0062] When an alkaline agent is extracted from seawater through electrolysis, and then an alkaline agent is added to calcium waste material after adding an acidic agent, a calcium hydroxide-based calcium agent is produced. In this case, the ground improvement agent containing calcium hydroxide becomes stronger.

[0063] When a soil improvement agent is mixed with seawater and applied to the ground, the ground becomes stronger.

[0064] If the renewable energy is electricity generated by a wind turbine or solar power generator G installed near where the electrolysis device 10 collects seawater, the cost of transmitting electricity to the electrolysis device 10 can be reduced. Furthermore, if the electrolysis device 10, the alkaline agent manufacturing device 11, the acid agent manufacturing device 12, and the calcium agent manufacturing device 13 constitute a plant and are installed near where the electrolysis device 10 collects seawater, the cost of delivering seawater can be reduced.

[0065] (Second Embodiment) Next, a second embodiment will be described with reference to Figures 4 and 5. Note that parts identical to or corresponding to those in the first embodiment will be given the same reference numerals, and only the different configurations and operations will be described. The same applies to other embodiments and modifications.

[0066] As shown in Figure 4, the ground improvement system 2 does not necessarily have to include the calcium agent manufacturing device 13. The alkaline agent manufactured by the alkaline agent manufacturing device 11 is transported to the ground improvement agent adjustment device 14.

[0067] The receiving section of the ground improvement agent adjustment device 14 receives fine powder of blast furnace granulated slag from the steelworks and alkaline agent from the alkaline agent manufacturing device 11, the mixer section mixes these together, and the discharge section discharges the adjusted ground improvement agent.

[0068] The ground improvement agent adjustment device 14 prepares the ground improvement agent by mixing fine powder of granulated blast furnace slag with an alkaline agent that solidifies the granulated blast furnace slag. The pH concentration due to the alkaline agent is adjusted with water to a concentration that makes it easy for the granulated blast furnace slag to harden, according to the target soil type.

[0069] Next, an example procedure for ground improvement system 2 will be explained using Figure 5.

[0070] As shown in Figure 5, the ground improvement system 2 performs electrolysis of seawater using renewable energy, as in step S1 (step S11).

[0071] Next, the ground improvement system 2 manufactures an alkaline agent as in step S2 (step S12).

[0072] The manufactured alkaline agent is transported to the ground improvement agent adjustment device 14.

[0073] Next, the ground improvement system 2 manufactures an acid agent as in step S3 (step S13).

[0074] Next, the ground improvement system 2 prepares a ground improvement agent containing blast furnace slag powder and an alkaline agent (step S14). Specifically, the ground improvement agent preparation device 14 receives fine powder of blast furnace granulated slag from the steelworks and an alkaline agent from the alkaline agent manufacturing device 11, each in a predetermined proportion, from the receiving section.

[0075] Next, the ground improvement agent is mixed in the mixer section of the ground improvement agent adjustment device 14, and the adjusted ground improvement agent is discharged from the discharge section.

[0076] In this manner, the ground improvement agent preparation device 14 prepares a ground improvement agent containing an alkaline agent and blast furnace slag powder to produce the ground improvement agent.

[0077] Next, the ground improvement system 2 applies a ground improvement agent (step S15), as in step S6. A ground improvement agent containing an alkaline agent and blast furnace slag powder is applied to the ground, as in step S6.

[0078] According to the ground improvement system 2 of this embodiment, the electrolysis device 10 electrolyzes seawater using electricity generated by the power generation device G using renewable energy, the alkaline agent production device 11 extracts an alkaline agent, and the ground improvement agent adjustment device 14 adjusts the alkaline agent and applies the resulting ground improvement agent, which contains blast furnace slag powder, to the ground. As a result, the slag powder derived from metal smelting hardens with the alkaline agent extracted from seawater using renewable energy that does not generate CO2, thus improving the ground without using cement and reducing CO2 emissions. Therefore, low-carbon ground improvement becomes possible. In this case, calcium waste material does not need to be used.

[0079] (Third embodiment) Next, a third embodiment will be described using Figures 6 and 7.

[0080] As shown in Figure 6, the ground improvement system 3 prepares the ground improvement agent by introducing calcium from the calcium agent production device 13 and sodium hydroxide, which is an alkaline agent from the alkaline agent production device 11, into the ground improvement agent preparation device 14, and mixing them with blast furnace granulated slag powder.

[0081] Next, an example procedure for ground improvement system 3 will be explained using Figure 7.

[0082] As shown in Figure 2, the ground improvement system 3 performs electrolysis of seawater using renewable energy, as in step S1 (step S21).

[0083] Next, the ground improvement system 3 manufactures an alkaline agent as in step S2 (step S22).

[0084] In this way, the electrolysis apparatus 10 and the alkaline agent manufacturing apparatus 11 manufacture an alkaline agent by electrolyzing seawater with electricity generated from renewable energy and extracting the alkaline agent.

[0085] The manufactured alkaline agent is transported to the ground improvement agent adjustment device 14.

[0086] Next, the ground improvement system 3 manufactures an acid agent as in step S3 (step S23).

[0087] Next, as shown in step S4, the ground improvement system 3 produces a calcium agent such as calcium hydroxide, which has high solubility in water, from biologically derived calcium waste material (step S24).

[0088] Next, the ground improvement system 3 prepares a ground improvement agent containing blast furnace slag powder, an alkaline agent, and a calcium agent, as shown in step S5 (step S25).

[0089] Next, the ground improvement agent is mixed in the mixer section of the ground improvement agent adjustment device 14, and the adjusted ground improvement agent is discharged from the discharge section.

[0090] In this manner, the ground improvement agent preparation device 14 prepares a ground improvement agent containing an alkaline agent, a calcium agent, and blast furnace slag powder to produce the ground improvement agent.

[0091] Next, the ground improvement system 1 applies a ground improvement agent (step S26), as in step S6. As in step S6, a ground improvement agent containing a calcium agent, an alkaline agent, and blast furnace slag powder is applied to the ground.

[0092] According to the ground improvement system 3 of this embodiment, the electrolysis device 10 electrolyzes seawater using electricity generated by the power generation device G using renewable energy, the alkaline agent production device 11 extracts an alkaline agent and an acidic agent, the calcium agent production device 13 adds the extracted acidic agent to calcium waste material to extract a calcium agent with higher water solubility than the calcium waste material, and the ground improvement agent adjustment device 14 adjusts the ground improvement agent containing calcium agent, alkaline agent and blast furnace slag powder. When this is applied to the ground, the blast furnace slag powder, which has latent hydraulic properties, hardens due to the alkaline agent extracted from seawater using renewable energy that does not generate CO2, and the calcium agent, which has higher water solubility than the calcium waste material, obtained by adding the extracted acidic agent to calcium waste material. Therefore, the ground can be improved without using cement and with reduced CO2 emissions. As a result, low-carbon ground improvement becomes possible.

[0093] (modified version) Next, a modified example will be explained using Figure 8.

[0094] Figure 8 shows a modified version of the ground improvement system concept, in which the seawater component is made more effective compared to the above embodiment.

[0095] As shown in Figure 8, renewable energy may be used to extract calcium and magnesium agents such as magnesium chloride from seawater as solidification accelerators for ground improvement agents. The magnesium agent may also be the magnesium component contained in an aqueous solution obtained by electrolyzing seawater. Alternatively, seawater may be directly mixed with the ground improvement agent. The ground improvement agent preparation device 14 may utilize calcium sulfate obtained from seawater as aggregate. Concentration or drying is carried out using renewable energy. An apparatus for extracting calcium and magnesium agents from seawater is added to a plant like the one shown in Figure 2.

[0096] By utilizing the components of seawater and using renewable energy to obtain raw materials for ground improvement agents from seawater, low-carbon ground improvement becomes possible.

[0097] Furthermore, as a ground improvement agent, a mixture of slag powder derived from metal smelting and seawater can be used as is. Calcium compounds such as calcium chloride and magnesium compounds such as magnesium chloride contained in seawater solidify the slag powder. Since seawater is used as is, ground improvement can be achieved without using cement, reducing CO2 emissions. Because seawater is simply used, there is no need to extract or decompose specific components, thus further reducing CO2 emissions and improving the ground.

[0098] Alternatively, renewable energy can be used to remove some of the water from seawater and concentrate it. The concentrated seawater can then be added to slag powder derived from metal smelting to prepare a ground improvement agent. In this case as well, ground improvement can be achieved without using cement, while reducing CO2 emissions.

[0099] (Examples) Next, the examples will be described using Table 1.

[0100] Table 1 TIFF2026091874000002.tif34158

[0101] As shown in Table 1, ground improvement agents were manufactured and their strengths compared for experiments 1 to 4.

[0102] Experiment No. 1 involved adding only water (W) to blast furnace slag powder (BF), Experiment No. 2 involved adding water (W) to a ground improvement agent made from blast furnace slag powder (BF) and calcium hydroxide (CH) produced from seashells, Experiment No. 3 involved adding only seawater (SW) to blast furnace slag powder (BF), and Experiment No. 4 involved adding water (W) to a ground improvement agent made from blast furnace slag powder (BF) and calcium hydroxide (CH) produced from seashells.

[0103] Compressive strength was measured on the materials used in the experiment three days after fabrication. (Water or seawater liquid) The ratio of liquid to solid components of the ground improvement agent was 40%.

[0104] Comparing Experiment 1 and Experiment 2, the compressive strength increased from 11.6 [N / mm2] to 13.6 [N / mm2] when the ground improvement agent contained calcium. Comparing Experiment 3 and Experiment 4, the compressive strength increased from 14.5 [N / mm2] to 15.4 [N / mm2] when the ground improvement agent contained calcium. The highest compressive strength was achieved when seawater was added to the ground improvement agents containing blast furnace slag powder and calcium.

[0105] Furthermore, the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention. [Explanation of Symbols]

[0106] 1: Ground improvement system 10: Electrolysis apparatus 11: Alkaline agent manufacturing equipment 12: Acid manufacturing equipment 13: Calcium preparation manufacturing equipment 14: Ground Improvement Agent Adjustment Device

Claims

[Claim 1] A ground improvement agent comprising calcium powder derived from calcium waste materials, which has a higher water solubility than the said calcium waste materials, and slag powder derived from metal smelting.

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