Solidified body, roadbed material, and method for producing solidified body

Abstract

[Problem] To provide a solidified body and a method for producing the solidified body, whereby it is possible to produce a solidified body in which CO2 is fixed without performing a deaeration step or a carbonation step in an airtight container. [Solution] This solidified body comprises: a binder; at least one of a carbonated steelmaking slag, a woody material, a synthetic resin, and natural fibers; and water. The content of at least one of the carbonated steelmaking slag, woody material, synthetic resin, and natural fibers is 1%-90% by mass.

Description

Solidified body, roadbed material, and method for manufacturing solidified body

[0001] The present invention relates to a solidified body, a roadbed material, and a method for manufacturing a solidified body.

[0002] Various decarbonization technologies are being considered to achieve carbon neutrality. ２ Carbonate and concrete-related technologies using other CO ２ It is easier to put into practical use than CO ２ The potential for fixation is high. ２ A method for producing a carbonated iron and steel slag solidified body using the above raw materials is disclosed.

[0003] Patent No. 5263190

[0004] In Patent Document 1, the inside of an airtight container is degassed, and then a carbonation step is carried out for a long period of time by supplying carbon dioxide gas to cause a carbonation reaction in the uncarbonated Ca-containing raw material of the preform, which poses a problem of a very large load. Furthermore, there is also a problem that it is difficult to carbonate the entire inside of the solidified body. The present invention has been made in view of such problems, and its purpose is to provide a method for producing CO 2 without carrying out a degassing step or a carbonation step in an airtight container. ２ The present invention aims to provide a solidified body capable of fixing a soil, a roadbed material containing the solidified body, and a method for manufacturing the solidified body.

[0005] The means for solving the above problems are as follows. [1] A solidified body comprising a binder, at least one of carbonated steelmaking slag, a wood material, a synthetic resin, and a natural fiber, and water, wherein the content of the at least one of the carbonated steelmaking slag, the wood material, the synthetic resin, and the natural fiber is 1% by mass or more and 90% by mass or less. [2] The solidified body according to [1], wherein the carbonated steelmaking slag is a ground carbonized steelmaking slag having a particle size of 1 mm or less, and the content of carbonates contained in the ground carbonized steelmaking slag is 1% by mass or more. [3] The solidified body according to [1] or [2], wherein the wood material is at least one of wood flour, wood chips, wood wool, wood fiber, pulp, semi-carbonized material, carbide, cellulose nanofiber, carbon nanofiber, and carbon fiber. [4] The solidified body according to [1] or [2], wherein the wood material contains at least one of semi-carbides and carbides, and the content of the at least one of the semi-carbides and carbides contained in the wood material is 1 mass% or more. [5] The solidified body according to any of [1] to [4], wherein the binder is at least one of ground granulated blast furnace slag, ground granulated steelmaking slag, vitreous aluminosilicate, hydrated lime, cement, and waste concrete. [6] The solidified body according to [5], wherein the ground granulated steelmaking slag is at least one of converter slag, secondary refining slag, hot metal pretreatment slag, and electric furnace slag. [7] The solidified body according to [5], wherein the vitreous aluminosilicate is at least one of fly ash, volcanic ash, and silica fume. [8] The solidified body according to any of [1] to [7], wherein the water is at least one of fresh water, salt water, seawater, hot spring water, and aqueous sodium hydroxide solution. [9] A roadbed material having a content of the solidified material according to [1] of 1% by mass or more.

[10] A method for producing a solidified material, comprising: a kneading step of kneading a binder, at least one of carbonated steelmaking slag, wood material, synthetic resin, and natural fiber, and water to form a mixture; and a solidification step of shaping and solidifying the mixture, wherein in the kneading step, the content of the at least one of carbonated steelmaking slag, wood material, synthetic resin, and natural fiber is 1% by mass or more and 90% by mass or less.

[11] The method for producing a solidified body according to

[10] , wherein in the kneading step, the water and the binder are mixed and kneaded so that the mass ratio of the water and the binder is 0.1 or more and 0.7 or less.

[0006] According to the present invention, a solidified body is produced by solidifying a binder and a raw material having carbon fixation ability with a hydrate, and therefore the solidified body according to the present invention can be produced without undergoing a degassing step or a carbonation step in an airtight container. ２ By using such a solidified body, a large amount of CO ２ This will make it easier to produce solidified bodies with carbon dioxide fixed in them, which will contribute to the realization of carbon neutrality.

[0007] [Embodiment 1] Hereinafter, the present invention will be described through an embodiment of the present invention. ２ This is then mixed with water to obtain a solidified product. ２ As a first embodiment, a solidified body including a binder, carbonated steelmaking slag, and water will be described.

[0008] A method for manufacturing a solidified body according to the first embodiment will be described. First, a binder, which is the raw material for the solidified body, carbonated steelmaking slag, and water are kneaded to form a mixture. This process is the kneading step. Next, the mixture of binder, carbonated steelmaking slag, and water is formed into a predetermined shape and cured in air, a humid atmosphere, or water for at least one day to solidify by a hydration reaction. This process is the solidification step. By solidifying the raw materials by a hydration reaction in this way, CO ２ The solidified material thus produced can be used, for example, as a seawall material, foot protection material, fishing reef, wall material, sand compaction pile material, calcia modifier, roadbed material, or aggregate.

[0009] The binder is a material that functions to bind particles together and solidify them through a hydration reaction. Examples of binders include at least one of ground granulated blast furnace slag, ground granulated steelmaking slag, vitreous aluminosilicate, hydrated lime, cement, and waste concrete. The particle size of the ground granulated blast furnace slag and ground granulated steelmaking slag may be 1 mm or less. A particle size of 1 mm or less means a particle size that can be sieved through a sieve with 1 mm openings.

[0010] The binder is mixed so that the binder content in the solidified body is 10% by mass or more and 99% by mass or less. The ground steelmaking slag used as the binder is, for example, at least one of converter slag, secondary refining slag, hot metal pretreatment slag, and electric furnace slag. The vitreous aluminosilicate used as the binder is, for example, at least one of fly ash, volcanic ash, and silica fume. Table 1 below shows an example of the component composition.

[0011]

[0012] The water may be at least one of fresh water, salt water, seawater, hot spring water, and aqueous sodium hydroxide solution. Any water containing moisture is sufficient, but the use of salt water or seawater containing chloride ions, or hot spring water containing sulfate ions, thiosulfate ions, and chloride ions, or aqueous sodium hydroxide solution containing high pH sodium ions, promotes the improvement of the strength of the mixture obtained by kneading, and improves the strength of the solidified body. The use of hot spring water containing carbonate ions increases the CO2 content of the solidified body. ２ The amount of fixation increases. Table 2 below shows examples of components contained in these waters.

[0013]

[0014] The water-binder ratio, which indicates the mass ratio of water to binder (water mass / binder mass) during kneading, is preferably 0.1 or more and 0.7 or less. If the water-binder ratio during kneading is less than 0.1, the fluidity of the mixture obtained in the kneading step decreases, which is undesirable. On the other hand, if the water-binder ratio during kneading is greater than 0.7, the time required to improve the strength of the solidified body in the solidification step increases, and the strength of the solidified body decreases, which is undesirable.

[0015] Carbonated steelmaking slag is mixed so that the content of carbonated steelmaking slag in the solidified body is 1% by mass or more and 90% by mass or less. When the content of carbonated steelmaking slag is less than 1% by mass, the CO ２ On the other hand, if the content of carbonated steelmaking slag is more than 90 mass %, the amount of binder decreases and the strength of the solidified body decreases, which is also undesirable. Carbonated steelmaking slag is produced by adding steam to steelmaking slag and then adding CO ２ Instead of adding steam to the steelmaking slag, the steelmaking slag is kept in water and CO ２ Carbonated steelmaking slag may be produced by introducing a CO containing gas and carrying out the carbonation treatment for one day. ２ CO contained in gas ２ The concentration should be 10% by volume or more. ２ The contained gas is CO emitted from the manufacturing process equipment in the steelworks. ２ Exhaust gas with a concentration of 10% by volume or more may be used.

[0016] It is preferable to use finely ground steelmaking slag with a particle size of 1 mm or less as the steelmaking slag to be used for the carbonated steelmaking slag. A particle size of 1 mm or less means a particle size that can be sieved through a sieve with 1 mm openings. By using finely ground steelmaking slag with a particle size of 1 mm or less, a reaction promotion effect can be obtained by increasing the reaction interface area during the carbonation treatment, and the CO ２ By using finely ground carbonated steelmaking slag with a particle size of 1 mm or less, the specific surface area increases in the solidification step, facilitating the supply of alkali and improving the strength of the solidified body.

[0017] Carbonated steelmaking slag contains carbonates. The carbonates may be, for example, calcium carbonate, calcium carbonate hydrate, magnesium carbonate, or magnesium carbonate hydrate. It is preferable to carbonate steelmaking slag so that the carbonate content in the carbonated steelmaking slag is 1 mass % or more. Carbonates include CO ２ Therefore, the amount of carbonate contained is also increased. ２Therefore, by using carbonated steelmaking slag with a carbonate content of 1 mass % or more as the raw material for the solidified body, the CO ２ The higher the carbonate content in the carbonated steelmaking slag, the more CO is fixed in the solidified body. ２ Therefore, there is no need to set an upper limit for the carbonate content.

[0018] In this way, by replacing part of the binder in the solidified body with carbonated steelmaking slag, ２ The solidified body according to the first embodiment can be produced by solidifying the binder and the carbonated steelmaking slag with a hydrate, so that the solidified body can be produced without carrying out a degassing process or a carbonation process in an airtight container. ２ While calcium carbonate and biochar, which are used as fixing materials, produce residues of components other than Ca and ash components, the solidified body produced using carbonated steelmaking slag can also suppress the generation of such residues.

[0019] [Embodiment 2] Next, a solidified body containing a binder, a wood material, and water will be described as embodiment 2. The binder and water are the same as those in embodiment 1, and therefore description thereof will be omitted.

[0020] A method for producing a solidified body according to the second embodiment will be described. First, a binder, which is the raw material for the solidified body, wood material crushed to 4.75 mm or less, and water are kneaded together to form a mixture. This process is the kneading step. Wood material of 4.75 mm or less is wood material that can be sieved through a sieve with a mesh size of 4.75 mm among the crushed wood material. Next, the mixture of binder, wood material, and water is formed into a predetermined shape and cured in air, a humid atmosphere, or water for at least one day to solidify by a hydration reaction. This process is the solidification step. By solidifying the raw materials by a hydration reaction in this way, CO ２ A solidified body in which the particles are fixed can be produced.

[0021] The wood material is mixed so that the content of the wood material in the solidified body is 1% by mass or more and 90% by mass or less. The wood material is, for example, one of wood powder, wood chips, wood wool, wood fiber, pulp, semi-carbonized material, carbonized material, cellulose nanofiber, carbon nanofiber, and carbon fiber. By using the wood material as the raw material for the solidified body, the CO ２ The specific gravity of the solidified body can be adjusted by changing the ratio of the raw wood material. High-specific gravity solidified bodies are used as artificial stones to be installed underwater. Using high-specific gravity solidified bodies as artificial stones results in artificial stones with excellent wave stability. Low-specific gravity solidified bodies are used as revetment materials, exterior wall materials, and floating fish reefs. Using low-specific gravity solidified bodies makes construction easier, which can shorten the construction period for revetment and exterior wall construction.

[0022] Wood materials have high water absorption. Therefore, by using wood materials as the raw material for the solidified body, heat generation during the hydration reaction in the solidification step is suppressed, and the occurrence of cracks in the produced solidified body can be suppressed. Furthermore, by using wood materials as the raw material for the solidified body, drying shrinkage of the solidified body is also suppressed, so that a solidified body with excellent thermal insulation, sound insulation, and fire resistance, as well as moisture-regulating effects and excellent biocompatibility can be produced.

[0023] It is preferable that the wood material contains at least one of semi-carbonized material and carbide. Semi-carbonized material and carbide function as adsorbents, and therefore adsorb the lye contained in low-cost wood materials, which causes a delay in solidification of the solidified body. Therefore, by using wood materials containing semi-carbonized material and carbide, it becomes possible to produce solidified bodies using low-cost wood materials. Semi-carbonized material can be produced by heating wood materials in an oxygen-free or low-oxygen reducing atmosphere at 200°C or higher but lower than 300°C. Carbonized material can be produced by heating wood materials in an oxygen-free or low-oxygen reducing atmosphere at 300°C or higher but lower than 1000°C.

[0024] The content of at least one of semi-carbides and carbides contained in the wood material is preferably 1% by mass or more. If the content of at least one of semi-carbides and carbides is less than 1% by mass, the effect of inhibiting solidification delay cannot be obtained, making it impossible to use low-cost wood materials. On the other hand, the higher the content of semi-carbides and carbides, the greater the effect of inhibiting solidification delay. Therefore, there is no need to set an upper limit for the content of semi-carbides and carbides.

[0025] In this way, even if wood material is used instead of carbonated steelmaking slag, CO ２ The solidified body according to the second embodiment can also be produced by solidifying the binder and wood material with a hydrate, so that the solidified body can be produced without carrying out a degassing process or a carbonation process in an airtight container.

[0026] [Embodiment 3] A solidified body containing a binder, a synthetic resin, and water will be described as embodiment 3. The binder and water are the same as those in embodiment 1, and therefore description thereof will be omitted.

[0027] The binder, which is the raw material for the solidified body, synthetic resin crushed to 4.75 mm or less, and water are kneaded together to form a mixture. This process is the kneading step. Synthetic resin of 4.75 mm or less is crushed synthetic resin that can be sieved through a 4.75 mm mesh sieve. Next, the mixture of binder, synthetic resin, and water is molded into a predetermined shape and cured in air, a humid atmosphere, or water for at least one day to solidify through a hydration reaction. This process is the solidification step. By solidifying the raw materials through a hydration reaction in this manner, the solidified body according to embodiment 3 can be produced.

[0028] The synthetic resin is mixed so that the content of the synthetic resin in the solidified body is 1% by mass or more and 90% by mass or less. The synthetic resin is, for example, one of solid synthetic polymer compounds such as synthetic rubber waste, waste tires, polystyrene foam waste, polyvinyl chloride waste, polyethylene waste, polystyrene waste, and synthetic fiber waste. It is preferable to use waste plastics such as polystyrene foam waste, polyvinyl chloride waste, polyethylene waste, polystyrene waste, and synthetic fiber waste as the synthetic resin. Using synthetic resin as the raw material for the solidified body improves the insulating properties of the solidified body. Furthermore, it becomes possible to produce lightweight solidified bodies and solidified bodies with elasticity.

[0029] In this way, even if synthetic resin is used instead of carbonated steelmaking slag, CO ２ The solidified body according to the third embodiment can also be produced by solidifying the binder and synthetic resin with a hydrate, and therefore can be produced without the need for a degassing process or a carbonation process in an airtight container.

[0030] [Embodiment 4] A solidified body containing a binder, natural fibers, and water will be described as embodiment 4. The binder and water are the same as those in embodiment 1, and therefore description thereof will be omitted.

[0031] The binder, which is the raw material for the solidified body, natural fibers cut to 4.75 mm or less, and water are kneaded together to form a mixture. This process is the kneading step. Next, the mixture of binder, natural fibers, and water is formed into a predetermined shape and cured in air, a humid atmosphere, or water for at least one day to solidify through a hydration reaction. This process is the solidification step. By solidifying the raw materials through a hydration reaction in this manner, the solidified body of embodiment 4 can be produced.

[0032] Natural fibers are mixed so that the natural fiber content in the solidified body is 1% by mass or more and 90% by mass or less. The natural fibers are, for example, plant fibers such as cotton, hemp, linen, rice husks, palm kernel shells, and banana peels, or animal fibers such as wool, cashmere, and silk. Using natural fibers as a raw material for the solidified body improves the strength of the solidified body. Furthermore, it becomes possible to produce lightweight solidified bodies and solidified bodies with elasticity.

[0033] Thus, even when natural fibers are used instead of carbonated steelmaking slag, ２ The solidified body according to the fourth embodiment can also be produced by solidifying the binder and natural fibers with a hydrate, and therefore can be produced without the need for a degassing process or a carbonation process in an airtight container.

[0034] In the first to fourth embodiments, the solidified body is described using an example of a solidified body containing a binder, carbonated steelmaking slag, a wood material, a synthetic resin or natural fibers, and water. However, this is not limiting. A solidified body may be produced using a wood material together with carbonated steelmaking slag, a synthetic resin together with carbonated steelmaking slag, or a natural fiber together with carbonated steelmaking slag. Furthermore, a solidified body may be produced using a wood material together with synthetic resin, a wood material together with natural fibers, or a synthetic resin together with natural fibers. That is, the solidified body according to the present embodiment includes a binder, at least one of carbonated steelmaking slag, a wood material, a synthetic resin, and natural fibers, and water, and the content of at least one of carbonated steelmaking slag, a wood material, a synthetic resin, and natural fibers is 1% by mass or more and 90% by mass or less.

[0035] Furthermore, the solidified body may contain a binder, carbonated steelmaking slag, wood material, synthetic resin or natural fiber, water, and fine aggregate, or may contain a binder, carbonated steelmaking slag, wood material, synthetic resin or natural fiber, water, fine aggregate, and coarse aggregate. Even with such a solidified body, CO2 can be produced without a degassing step or a carbonation step in an airtight container. ２ becomes a fixed solidified body.

[0036] The roadbed material obtained in this embodiment, in which the content of the solidified body is 1 mass % or more, is ２In addition to the solidified material obtained in this embodiment, the roadbed material may be mixed with at least one of carbonated steel slag, wood material, synthetic resin, and natural fiber. When incorporating the solidified material into the roadbed material, the solidified material is pulverized so that the entire roadbed material satisfies CS-40 specified in JIS A 5015:2018 "Iron and steel slag for roads."

[0037] Next, an example will be described in which a solidified body was produced by adjusting the mixing ratio of binder, carbonated steelmaking slag (containing calcium carbonate, which is a carbonate), wood material, synthetic resin, natural fiber, and water. Carbonated steelmaking slag fine powder with a particle size of 1 mm or less was used as the carbonated steelmaking slag. The wood material and synthetic resin were crushed to 4.75 mm or less using a crusher, and the natural fiber was cut to 4.75 mm or less using a cutter mill. The mixing ratio of these raw materials, the water binding ratio, whether or not solidification was performed, and the CO ２ The amounts of fixation are shown in Table 3. The binder, carbonated ground steel slag, wood material, synthetic resin, and natural fiber materials used in each of Invention Examples 1 to 17 and Comparative Examples 1 to 4 are shown in Table 4.

[0038] The raw materials for each solidified body shown in Table 3 were placed in a test room maintained at a temperature of 20±3°C and a relative humidity of 60% or higher. 15 L of the raw materials were placed in a 20 L mortar mixer. After 30 seconds of dry mixing, water was added and the mixture was mixed at 100 rpm for 90 seconds. The raw materials were then filled into a cylindrical container (φ100 mm x 200 mm) and sealed and cured for up to 7 days to produce a solidified body.

[0039] The semi-carbonized material contained in the wood material was produced by treating wood flour with an average particle size of 1 mm using superheated steam at 250°C for 10 minutes. The charcoal contained in the wood material was produced by treating wood flour with an average particle size of 300 μm using superheated steam at 300°C for 20 minutes. The average particle size of the wood flour is the volume mean diameter defined by the following formula (1):

[0040] In the above formula (1), x ｉ is the representative particle size (mm) of the particle size range, and n ｉ is the number of particles.

[0041] If the compressive strength of the produced solidified body was 1 MPa or more, the solidification was judged as "Good," and if the compressive strength of the solidified body was less than 1 MPa, the solidification was judged as "Poor." The compressive strength of the solidified body was measured in accordance with JIS A 1108:2018 "Testing method for compressive strength of concrete."

[0042]

[0043]

[0044] As shown in Table 3, in Examples 1 to 17, the kneaded mixed raw material was hydrated and solidified, and CO ２ From this result, it was found that the solidified body according to this embodiment can produce CO 2 without the need for a degassing process or a carbonation process in an airtight container. ２ On the other hand, in Comparative Examples 1 and 2, although solidified bodies were produced by hydration solidification, the raw materials for the solidified bodies did not contain carbonated steel slag powder, wood material, or synthetic resin, so the CO in the solidified bodies was not ２ The fixed amount becomes 0, and CO ２ In Comparative Examples 3 and 4, since the raw material did not contain a binder, the raw material did not hydrate and solidify, and a solidified body could not be produced.

Claims

1. A binder; At least one of carbonated steel slag, wood material, synthetic resin, and natural fiber; Water, A solidified body, wherein the content of at least one of the carbonated steelmaking slag, wood material, synthetic resin and natural fiber is 1% by mass or more and 90% by mass or less.

2. The carbonated steelmaking slag is a finely powdered carbonated steelmaking slag having a particle size of 1 mm or less, 2. The solidified body according to claim 1, wherein the content of carbonates contained in the carbonated ground steelmaking slag is 1 mass % or more.

3. 2. The solidified body according to claim 1, wherein the wood material is at least one of wood powder, wood chips, wood wool, wood fiber, pulp, semi-carbonized material, carbonized material, cellulose nanofiber, carbon nanofiber, and carbon fiber.

4. The wood material includes at least one of semi-carbonized material and carbonized material, The solidified body according to claim 1 , wherein the content of at least one of the semi-carbonized material and the carbide contained in the wood material is 1 mass % or more.

5. The solidified body according to any one of claims 1 to 4, wherein the binder is at least one of ground granulated blast furnace slag, ground granulated steel slag, vitreous aluminosilicate, hydrated lime, cement, and waste concrete.

6. The solidified body according to claim 5, wherein the ground steelmaking slag is at least one of converter slag, secondary refining slag, hot metal pretreatment slag, and electric furnace slag.

7. 6. The solidified body according to claim 5, wherein the vitreous aluminosilicate is at least one of fly ash, volcanic ash, and silica fume.

8. The solidified body according to claim 1 , wherein the water is at least one of fresh water, salt water, seawater, hot spring water, and an aqueous solution of sodium hydroxide.

9. A roadbed material having a content of the solidified body according to claim 1 of 1 mass% or more.

10. A method for producing a solidified body, comprising the steps of: a kneading step of kneading a binder, at least one of carbonated steel slag, wood material, synthetic resin, and natural fiber, and water to obtain a mixture; and a solidification step of molding and solidifying the mixture, In the kneading step, the carbonated steelmaking slag, wood material, synthetic resin and natural fiber are mixed and kneaded so that the content of at least one of them is 1 mass% or more and 90 mass% or less.

11. The method for producing a solidified body according to claim 10, wherein in the kneading step, the water and the binder are mixed and kneaded so that a mass ratio of the water to the binder is 0.1 or more and 0.7 or less.