Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B5/00—Treatment of  metallurgical  slag ; Artificial stone from molten  metallurgical  slag 
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B5/00—Treatment of  metallurgical  slag ; Artificial stone from molten  metallurgical  slag 
  • C04B5/06—Ingredients, other than water, added to the molten slag or to the granulating medium or before remelting; Treatment with gases or gas generating compounds, e.g. to obtain porous slag
• • E—FIXED CONSTRUCTIONS
  • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
  • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
  • E01C3/00—Foundations for pavings
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

• the present invention relates to roadbed materials and methods for manufacturing roadbed materials.
• Patent Document 1 discloses a roadbed material in which calcium carbonate or magnesium carbonate produced by a carbonation reaction of slag is solidified and agglomerated as a binder.
• Patent Document 1 carbon dioxide gas or a gas containing carbon dioxide gas is blown into a slag pile or packed bed to solidify and agglomerate the granular slag, and the agglomerates are then crushed, sieved, etc. to adjust the particle size, thereby producing the roadbed material.
• granular slag is agglomerated, and the agglomerates are further crushed to produce the roadbed material, which poses an issue of a very large production load.
• the present invention was made in consideration of the problems with the conventional technology, and its purpose is to provide a roadbed material that contains granular carbonated steelmaking slag and raw materials with carbon fixation capacity without agglomerating these raw materials, and a method for manufacturing said roadbed material.
• the carbonated steelmaking slag is a finely powdered carbonated steelmaking slag having a particle size of 1 mm or less,
• the synthetic resin is at least one of synthetic rubber scraps, waste tires, polyvinyl chloride scraps, polyethylene scraps and synthetic fiber scraps, which are synthetic polymer compounds.
• the natural fibers are at least one of plant fibers and animal fibers.
• a method for manufacturing a roadbed material comprising a mixing step of mixing at least one of carbonated steelmaking slag, wood material, synthetic resin and natural fiber with steelmaking slag, wherein in the mixing step, the content of at least one of the carbonated steelmaking slag, wood material, synthetic resin and natural fiber is 1 mass% or more and 90 mass% or less.
• the carbonated steelmaking slag is a carbonated finely ground steelmaking slag produced by carbonating finely ground steelmaking slag having a particle size of 1 mm or less.
• the roadbed material according to the present invention is a roadbed material that has a low production load and can be easily manufactured. Furthermore, by using this roadbed material, it becomes possible to easily manufacture roadbed material in which CO2 is fixed, which can contribute to the realization of carbon neutrality.
• the roadbed material according to this embodiment is obtained by replacing a part of the amount of the mixture mixed with the roadbed material with a CO2- containing substance. This results in a roadbed material with fixed CO2 .
• a roadbed material containing carbonated steelmaking slag will be described.
• the roadbed material according to the first embodiment contains carbonated steel slag.
• the roadbed material according to the first embodiment containing carbonated steel slag is produced by carrying out a mixing step in which carbonated steel slag is mixed with at least one of non-carbonated steel slag, blast furnace slag, and electric furnace slag. These are then crushed and blended to satisfy the particle size composition of CS-40 specified in JIS A 5015:2018 "Iron and steel slag for roads".
• the carbonated steelmaking slag it is preferable to use carbonated finely ground steelmaking slag having a particle size of 1 mm or less, which is produced by carbonating finely ground steelmaking slag having a particle size of 1 mm or less.
• the carbonated steelmaking slag it is preferable for the carbonated steelmaking slag to be slag produced by carbonating finely ground steelmaking slag having a particle size of 1 mm or less.
• a particle size of 1 mm or less means a particle size that can be sieved under a sieve with a mesh size of 1 mm.
• Carbonated steelmaking slag can be produced by adding steam to steelmaking slag, introducing CO2- containing gas, and performing carbonation treatment for 10 minutes or more. Instead of adding steam to steelmaking slag, carbonated steelmaking slag may be produced by holding steelmaking slag in water, introducing CO2- containing gas into the water, and performing carbonation treatment for one day. Instead of adding steam to steelmaking slag, carbonated steelmaking slag may be produced by spraying water on steelmaking slag, introducing CO2- containing gas, and performing carbonation treatment for one day. The CO2 concentration of the introduced CO2- containing gas may be 1% by volume or more.
• the CO2- containing gas exhaust gas having a CO2 concentration of 10% by volume or more discharged from a manufacturing process facility in a steelworks may be used.
• the steelmaking slag used to produce carbonated steelmaking slag is at least one of converter slag, secondary refining slag, hot metal pretreatment slag, and electric furnace slag.
• Carbonated steelmaking slag contains carbonate introduced by the above-mentioned carbonation treatment.
• the carbonate is, for example, any one of calcium carbonate, calcium carbonate hydrate, magnesium carbonate, and magnesium carbonate hydrate. It is preferable to perform the carbonation treatment of steelmaking slag so that the carbonate content in the carbonated steelmaking slag is 1 mass% or more. Since carbonate contains CO2 , the amount of carbonate fixed in the roadbed material increases. Therefore, it is preferable to use carbonated steelmaking slag with a carbonate content of 1 mass% or more as a raw material for the roadbed material, and this increases the amount of CO2 fixed in the roadbed material. Since the amount of carbonate fixed in the roadbed material increases as the amount of carbonate contained in the carbonated steelmaking slag increases, there is no need to set an upper limit for the carbonate content.
• Carbonated steel slag is mixed into the roadbed material so that the content of carbonated steel slag is 1% by mass or more. This allows CO2 to be fixed in the roadbed material, contributing to the realization of carbon neutrality. Carbonated steel slag is mixed into the roadbed material so that the content of carbonated steel slag is 90% by mass or less. By making the content of carbonated steel slag 90% by mass or less, the bearing capacity of the roadbed material is improved, and the modified CBR of the roadbed material can be 60 or more.
• the modified CBR test is the CBR for roadbed material compacted to 95% of its maximum dry density.
• the roadbed material containing the carbonated steelmaking slag according to the first embodiment fixes CO2 in the roadbed material, so using this roadbed material can contribute to the realization of carbon neutrality. Furthermore, a corrected CBR of 60 or more can be secured, resulting in a roadbed material with high bearing capacity, and since the carbonated steelmaking slag contains calcium carbonate, etc., it also has the effect of suppressing alkali elution.
• a roadbed material containing a wood material will be described as embodiment 2.
• CO2 can be fixed in the roadbed material.
• the wood material is, for example, at least one of wood flour, wood chips, wood wool, wood fiber, pulp, semi-carbonized material, carbonized material, cellulose nanofiber, carbon nanofiber, and carbon fiber.
• the roadbed material including the wood material according to the second embodiment is manufactured by carrying out a mixing step of mixing the wood material with uncarbonated steel slag. Then, these are crushed and blended so as to satisfy the particle size composition of CS-40 specified in JIS A 5015:2018 "Iron and steel slag for roads".
• the wood material is mixed so that the content of the wood material in the roadbed material is 1% by mass or more and 90% by mass or less. This allows CO2 to be fixed in the roadbed material, and the modified CBR of the roadbed material can be 60 or more.
• Roadbed materials with a high specific gravity and a low content of wood material are suitable for use as roadbed materials for parking lots, for example.
• roadbed materials with a low specific gravity and a high content of wood material are suitable for use as paving materials for solar power generation facilities, for example.
• Using roadbed materials with a low specific gravity and a high content of wood material makes construction easier, and construction time can be shortened.
• Wood materials have high water absorption, and this high water absorption can suppress the separation of fine powder raw materials in the roadbed material during construction. For this reason, roadbed materials containing wood materials have a high filling rate during construction, making them roadbed materials with high bearing capacity. Furthermore, roadbed materials containing wood materials can absorb the expansion of the roadbed material by the wood materials, making them roadbed materials with excellent elasticity. As the modified CBR of the roadbed material improves as the elastic modulus of the roadbed material increases, roadbed materials containing wood materials have a higher modified CBR than roadbed materials that do not contain wood materials.
• roadbed materials that do not contain wood materials Due to its high water absorption, roadbed materials that do not contain wood materials have a natural moisture content of 2-3% by mass when piled up, whereas roadbed materials that contain wood materials have a natural moisture content of 6-7% by mass when piled up. Due to this difference in natural moisture content, roadbed materials that contain wood materials generate less dust and other particles when piled up than roadbed materials that do not contain wood materials.
• the wood material contains at least one of semi-carbonized materials and charcoal.
• Semi-carbonized materials and charcoal contain many pores, which further increases the water absorption of the wood material. For this reason, a roadbed material containing a wood material containing at least one of semi-carbonized materials and charcoal has a higher filling rate during construction and a higher bearing capacity.
• Semi-carbonized materials can be produced by heating wood materials in an oxygen-free or low-oxygen reducing atmosphere at 200°C or higher and lower than 300°C. Carbonized materials can be produced by heating wood materials in an oxygen-free or low-oxygen reducing atmosphere at 300°C or higher and 1000°C or lower.
• the synthetic resin is, for example, at least one of synthetic rubber scraps, waste tires, polyvinyl chloride scraps, polyethylene scraps, and synthetic fiber scraps, which are synthetic polymer compounds.
• the synthetic fiber scraps are, for example, synthetic fiber scraps based on polyester, polyurethane, polyvinyl alcohol, polyacrylonitrile, and polypropylene, and do not include nylon resin fiber scraps, which are polyamide.
• the roadbed material containing synthetic resin according to the third embodiment is manufactured by carrying out a mixing step of mixing uncarbonated steel slag with synthetic resin. Then, these are crushed and blended so as to satisfy the particle size composition of CS-40 specified in JIS A 5015:2018 "Steel slag for roads".
• the synthetic resin is mixed so that the content of the synthetic resin in the roadbed material is 1% by mass or more and 90% by mass or less. This allows CO2 to be fixed in the roadbed material, and the modified CBR of the roadbed material can be 60 or more.
• a roadbed material containing natural fibers will be described as embodiment 4.
• natural fibers are at least one of plant fibers such as cotton, hemp, linen, rice husks, palm shells, and banana skins, and animal fibers such as wool, cashmere, and silk.
• the roadbed material containing natural fibers according to the fourth embodiment is manufactured by carrying out a mixing step of mixing uncarbonated steel slag with natural fibers. Then, these are crushed and blended so as to satisfy the particle size composition of CS-40 specified in JIS A 5015:2018 "Steel slag for roads".
• the natural fibers are mixed so that the content of natural fibers in the roadbed material is 1% by mass or more and 90% by mass or less. This allows CO2 to be fixed in the roadbed material, and the modified CBR of the roadbed material can be 60 or more.
• roadbed material By using natural fibers as the raw material for roadbed material, it is possible to produce roadbed material with high strength. Furthermore, by using natural fibers as the raw material for roadbed material, it is possible to produce lightweight roadbed material and roadbed material with a high elastic modulus. As the modified CBR of roadbed material improves as the elastic modulus of the roadbed material increases, roadbed material containing natural fibers will have a higher modified CBR than roadbed material that does not contain natural fibers.
• roadbed material containing carbonated steelmaking slag, wood material, synthetic resin, or natural fibers has been described as an example, but the present invention is not limited to this.
• Roadbed material may be manufactured using wood material together with carbonated steelmaking slag, roadbed material may be manufactured using synthetic resin together with carbonated steelmaking slag, or roadbed material may be manufactured using natural fibers together with carbonated steelmaking slag.
• roadbed material may be manufactured using synthetic resin together with wood material, roadbed material may be manufactured using natural fibers together with wood material, or roadbed material may be manufactured using natural fibers together with synthetic resin.
• the roadbed material according to this embodiment contains at least one of carbonated steel slag, wood material, synthetic resin and natural fibers, and the content of at least one of carbonated steel slag, wood material, synthetic resin and natural fibers is 1% by mass or more and 90% by mass or less.
• the roadbed material according to this embodiment can be made by mixing the raw materials of carbonated steel slag, wood material, synthetic resin and natural fibers and adjusting them to a specified particle size without agglomerating these raw materials, and therefore is a roadbed material that has a lower production load than conventional roadbed materials and can be easily manufactured.
• mixture ratio refers to the content ratio (mass%) of the mixed raw material contained in the roadbed material.
• Maximum particle size of the mixed raw material means that the entire amount passed through a sieve with the nominal mesh size specified in JIS Z 8801-1:2019 that corresponds to the maximum particle size (mm).
• Modified CBR is the CBR at a maximum dry density of 95%, and CBR is the load when a 5.0 cm diameter piston is inserted 2.5 mm or 5.0 mm into the surface of the roadbed material, expressed as a percentage of the standard load.
• the standard load is 13.4 kN for 2.5 mm penetration and 19.9 kN for 5.0 mm penetration.
• the semi-carbonized wood material was produced by treating wood powder with a particle size of 1 mm or less at 250°C for 10 minutes using superheated steam.
• the carbonized wood material was produced by treating wood powder with an average particle size of 300 ⁇ m or less at 300°C for 20 minutes using superheated steam.
• roadbed materials containing 1% by mass to 90% by mass of at least one of carbonated steel slag, wood material, synthetic resin, and natural fiber had a good balance of coarse and fine particles within the range of CS-40 particle size composition, and the filling density of the roadbed material was high, resulting in a high corrected CBR. From these results, it was confirmed that the roadbed materials of Examples 1 to 23 can fix CO2 and are high-bearing roadbed materials with a corrected CBR of 60 or more. The use of these roadbed materials can contribute to the realization of carbon neutrality.
• the roadbed material not containing carbonated steel slag, wood material, synthetic resin or natural fiber had a corrected CBR value of 60 or more, but was unable to fix CO2 in the roadbed material.
• the roadbed material containing 95% by mass, which is more than 90% by mass, of carbonated steel slag, wood material, synthetic resin or natural fiber had a high blending ratio of mixed raw materials, and the ratio of fine particles increased within the range satisfying the CS-40 particle size, decreasing the filling rate of the roadbed material and decreasing the corrected CBR to less than 60%.
• roadbed materials mixed with wood materials have a higher natural moisture content than other roadbed materials, resulting in roadbed materials with a higher corrected CBR. Furthermore, the higher natural moisture content allows fine powder to be adsorbed, so when roadbed materials containing wood materials are piled up for storage, the generation of dust and other particles can be suppressed more than with other roadbed materials.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Structural Engineering (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Road Paving Structures (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=95742869

Family Applications (1)

Country Status (3)

Cited By (1)

Citations (6)

Family Cites Families (3)

• 2024
  • 2024-07-23 JP JP2024560288A patent/JPWO2025104979A1/ja active Pending
  • 2024-07-23 WO PCT/JP2024/026376 patent/WO2025104979A1/ja active Pending
  • 2024-08-01 TW TW113128644A patent/TWI910750B/zh active

Patent Citations (6)

Also Published As

Similar Documents

Legal Events