JP2015175175A - Civil engineering material and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a civil engineering material and a manufacturing method thereof of using steel slag for expanding use.SOLUTION: A roadbed paving material 100 being a civil engineering material of using steel slag 10 is formed by mixing powdery slag 11 formed of the steel slag 10 and occupying 95 mass% or more in a rate of 450 μm or less in a particle diameter, sandy slag 12 formed of the steel slag 10 and having a particle diameter falling within a range of 0-5 mm and massive slag 14 being a massive aggregate having a particle diameter of 40 mm or less. At this time, the powdery slag 11, the sandy slag 12 and the massive slag 14 are respectively mixed at a blending rate of 8-21 mass%, 30-60 mass% and 28-56 mass%.

Description

  TECHNICAL FIELD The present invention relates to a civil engineering material that can be used as a roadbed material and a pavement material and that uses steel slag, and a method for producing the same.

Steel slag generated in the steel manufacturing process has been disposed of in the past, but in recent years, it has been recycled in the civil engineering field. For example, in Patent Document 1, blast furnace slag or steelmaking slag having a particle size of 5 to 40 mm, 50 to 90% by mass, granulated blast furnace slag having a particle size of 10 mm or less, and carbonaceous material. A water-permeable roadbed material containing 1 to 10% by mass is described. Patent Document 2 discloses a steelmaking slag having a water expansion ratio of more than 1.5% and not more than 6.0% and a particle size of not more than 40 mm, and a blast furnace in which the content with respect to the total amount is 5 mass% or more and 35 mass% or less. A simple pavement material formed by mixing granulated slag is described.
The blast furnace slow-cooled slag and the granulated blast furnace slag are by-produced in the production process of pig iron in the blast furnace, and the steelmaking slag is by-produced in the steelmaking process such as ordinary steel and special steel, and the production process of stainless steel.

Japanese Patent No. 4292953 JP 2012-52408 A

  In the water-permeable roadbed material of Patent Document 1, blast furnace granulated slag exists between particles that are separated from each other in a blast furnace slow cooling slag or a steelmaking slag. And this water-permeable roadbed material has obtained the bearing power by having as a main component the blast furnace slow cooling slag or steelmaking slag and blast furnace granulated slag which have the latent hydraulic property which reacts with water and hardens | cures. However, since the blast furnace slow-cooled slag and the granulated blast furnace slag have a low heat generation rate at the time of reaction with water and thereby a low curing rate, the water-permeable roadbed material of Patent Document 1 has a long time to develop the required strength. Cost. When the time until the strength development after the construction of the roadbed becomes longer, the time required for constructing the pavement and opening it as a road becomes longer. Therefore, the permeable roadbed material of Patent Document 1 Etc., and the application is narrowed.

  Moreover, in the simple pavement material of patent document 2, the water expansion ratio of steelmaking slag exceeds 1.5%. In the Japanese Industrial Standard “Road Steel Slag” (JIS A 5015), steel slag with a water expansion ratio of 1.5% or less by the water immersion expansion test method specified in Annex 2 is used as road steel slag. It stipulates that it is possible. For this reason, the simple pavement material of patent document 2 has the problem that the use will be limited. Moreover, since the simple pavement material of patent document 2 contains blast furnace granulated slag with content of 5 mass% or more and 35 mass% or less with respect to the simple pavement material whole quantity, it takes a long time for expression of required intensity | strength. It also has the problem.

  The present invention has been made to solve such problems, and provides a civil engineering material using a steelmaking slag that can be used as a roadbed material and a pavement material and is intended to expand its application, and a method for manufacturing the same. With the goal.

  In order to solve the above-mentioned problems, a civil engineering material according to the present invention is a civil engineering material using a steelmaking slag produced in a steelmaking process, and is produced from the steelmaking slag, and a ratio of a particle size of 450 μm or less is 95% by mass. Powdered slag produced from a mixture of powdered slag occupying the above, steel-made slag, sandy slag having a particle size in the range of 0 to 5 mm, and massive aggregate having a particle size of 40 mm or less. , Sandy slag and massive aggregate are mixed at a blending ratio of 8 to 21% by mass, 30 to 60% by mass and 28 to 56% by mass, respectively.

The sandy slag may be a porous crystal slag.
Sandy slag has a particle size of 0 to 5 mm, a water permeability coefficient of 5.0 × 10 ^{−3 to} 2.0 × 10 ⁻² cm / s, and a unit volume mass of 1.9 to 2.1 kg / liter. , 1.5 to 3.2% water absorption and 10 to 20% pore content of 0 to 120 μm diameter.
In the civil engineering material, the water permeability is 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻³ cm / s, the corrected CBR value is 80 to 200%, and the water expansion ratio is 0.3% or less. It may be.
The massive aggregate may be formed from granulated slag obtained by granulating powdered steelmaking slag.

The manufacturing method of the civil engineering material includes a powdered slag generation step that sequentially performs cooling, crushing, classification, and dehydration processing on the steelmaking slag to generate powdered slag, and slow cooling, crushing, and classification on the steelmaking slag. A sandy slag generating step for sequentially generating sandy slag, and a mixing step of mixing the powdery slag, the sandy slag and the massive aggregate in the above-mentioned mixing ratio.
The method may include the step of granulating powdered steelmaking slag to adjust the particle size to produce a massive aggregate prior to the mixing step.

  According to the civil engineering material and the manufacturing method thereof according to the present invention, it is possible to expand the use of the civil engineering material using the steelmaking slag.

It is a figure which classifies and shows each process which manufactures powdery slag and sandy slag. It is a figure which classifies and shows each process which manufactures a roadbed paving material concerning this embodiment using powdery slag and sandy slag. It is the schematic which shows the test state of rain resistance.

Hereinafter, the manufacturing method of the civil engineering material 100 in embodiment of this invention is demonstrated based on an accompanying drawing.
In the embodiment of the present invention, a civil engineering material using a steelmaking slag generated when melting stainless steel will be described as an example.
Referring to FIGS. 1 and 2 together, the process of manufacturing the civil engineering material 100 is roughly divided into a stainless steel making process 1 in which a steelmaking slag 10 as a raw material is generated, and a cooling process 2 for cooling the steelmaking slag 10. , Slag beneficiation treatment step 3 for classifying fine powdery slag 11 and sandy granular sandy slag 12 from steelmaking slag 10 after cooling, a part of the powdery slag 11 is granulated to produce a massive slag 14 It is comprised by the granulation process 4, and the mixing process 5 which mixes the powdery slag 11, the sandy slag 12, and the block slag 14 and produces | generates the civil engineering material 100 which is a roadbed pavement material. The roadbed paving material is a material that can be used as both a paving material and a roadbed material. Here, the massive slag 14 forms a massive aggregate.

  Referring to FIG. 1, in the steelmaking process 1, steelmaking slag 10 is generated when melting stainless steel, and the generated steelmaking slag 10 is collected in a slag pan. The steelmaking slag 10 is produced in a melting slag produced in a melting step in which raw materials are melted in an electric furnace to produce stainless steel hot metal, and in a desulfurization treatment step in which contained sulfur is removed from the produced hot metal. The desulfurization slag is composed of desulfurization slag and refining slag generated in a refining process for removing contained carbon in a converter and a vacuum degassing apparatus with respect to the molten iron after desulfurization. And before desulfurization treatment and after desulfurization treatment, molten slag and desulfurized slag are removed from the molten iron of stainless steel as steelmaking slag 10, and further, refined slag generated by a converter and a vacuum gas treatment device is used as steelmaking slag 10. Collected. The steelmaking slag 10 is composed of impurities in the raw materials and products of stainless steel in the steelmaking process, and includes a bare metal 15 which is a useful metal made of iron, chromium, nickel, etc. constituting the stainless steel. It is out.

In the present embodiment, as a hot metal desulfurization method, a KR method is used in which hot metal is stirred with a mechanically driven stirring blade while a desulfurizing agent is added to slag and remove sulfur contained in the hot metal. . In the KR method, since the desulfurization reaction between the hot metal and the desulfurization agent is promoted by stirring, a desulfurization agent mainly containing CaO (quick lime, calcium oxide) is used. For this reason, the desulfurization agent used in the present embodiment does not include CaF2 (fluorite, calcium fluoride) used in the past to promote the desulfurization reaction.
Then, the steel slag 10 obtained in this embodiment, for example, basicity (CaO _/ SiO 2: mass ratio of CaO contents to the SiO ₂ content) has become a 0.8 to 1.6, F (Fluorine) is contained at less than 0.4% by mass, CaO at 30 to 65% by mass, SiO ₂ at 20 to 50% by mass, and Al ₂ O ₃ at 5 to 10% by mass.

When the basicity is 0.8 to 1.6, adverse effects on the desulfurization treatment of the hot metal of the stainless steel are suppressed. The basicity has a great influence on the hot metal desulfurization reaction. In the steelmaking slag 10, when the basicity is less than 0.8, sufficient desulfurization reaction is not obtained between CaO contained in the steelmaking slag 10 and S (sulfur) contained in the hot metal during the desulfurization treatment. That is, when it exceeds 1.6, the fluidity of the steelmaking slag 10 is low during the desulfurization treatment, and the contact interface between the hot metal and the steelmaking slag 10 is reduced, and the desulfurization reaction is not promoted. The desulfurization reaction here refers to steelmaking slag produced in the melting process, desulfurization slag produced in the desulfurization treatment process, and all slag of refined slag produced in the converter and vacuum degassing treatment equipment. Desulfurization reaction. In the present embodiment, the desulfurization treatment method is a mechanical stirring type KR method, and fluorite (CaF ₂ ) that has been used to improve the slag fluidity is not used. It is necessary to ensure the fluidity of the steelmaking slag 10.

  Even if F-containing agents such as fluorite are not used, a slight amount of fluorine is inevitable due to mixing of F-containing raw materials such as scrap and ore, but the target fluorine content is set to less than 0.4% by mass. By this, the roadbed pavement material 100 produced | generated from the steelmaking slag 10 satisfies the reference | standard of the elution amount of the fluorine with respect to the water prescribed | regulated by soil environmental standard. As described above, in the present embodiment, since fluorite is not used for the desulfurization treatment, the F content in the composition of the steelmaking slag 10 can be kept low, and the roadbed paving material 100 can satisfy the soil environmental standards.

When the content of CaO is 30 to 65% by mass, effective hot metal desulfurization treatment of stainless steel becomes possible. CaO is a main component of the desulfurization material and an essential component for the desulfurization reaction. For this reason, hot metal can fully be desulfurized by the content rate of CaO in the steelmaking slag 10 being 30 mass% or more. On the other hand, when the content of CaO is excessive with respect to the content of SiO ₂ in the steelmaking slag 10, the basicity becomes too high and the fluidity of the slag deteriorates, and the desulfurization reaction by the steelmaking slag 10 is not promoted. For this reason, the fall of the desulfurization reaction by the fluidity deterioration of slag can be suppressed because the content rate of CaO in the steelmaking slag 10 is 65 mass% or less.

When the content ratio of SiO ₂ is 20 to 50% by mass, effective desulfurization treatment of the hot metal of stainless steel becomes possible. SiO ₂ is generated from a raw material of stainless steel and is generated as a deoxidation reaction product by a reducing agent. If the content of SiO ₂ is less than 20% by mass in the steelmaking slag 10, the basicity during the desulfurization process is too high, and the desulfurization reaction is not promoted. On the other hand, if the content of SiO ₂ exceeds 50% by mass, the basicity during the desulfurization treatment is too low and a sufficient desulfurization reaction cannot be obtained. Therefore, by the content of SiO ₂ is 20 to 50 mass% in the steel slag 10, it is possible to effectively promote the desulfurization reaction.

When the content of Al ₂ O ₃ is 5 to 10% by mass, the fluidity of the steelmaking slag 10 can be ensured. Al ₂ O ₃ is mixed from refractory bricks and stainless steel raw materials for each pan used for steelmaking. If the content of Al ₂ O ₃ in the steelmaking slag 10 is too low or too high, the melting point of the slag increases and the fluidity of the slag decreases.
And in the steelmaking slag 10, based on the empirical rule about the mixing ratio of raw materials and the element distribution ratio between the slag and stainless steel, the type and mixing ratio of the raw materials of the slag generation source are adjusted for each steel type to be melted. By doing so, the basicity and composition can be adjusted as described above.

  The steelmaking slag 10 generated and collected in the steelmaking process 1 of FIG. 1 is transferred to the cooling process 2 in a state of being put in a slag pan, and is cooled and solidified. At this time, the steelmaking slag 10 is gradually put in a state where it is put in the slag pot over 24 hours or more by a combination of air cooling by natural cooling in the atmosphere and sprinkling cooling that sprays and cools the slag pot. It is cooled. The steelmaking slag 10 is converted into a rock-like slag that is crystalline and includes a large number of pores by being gradually cooled.

  In the cooling process, the steelmaking slag 10 is from about 1100 ° C. after being put into the slag pan to start solidification to about 700 ° C. until the temperature of the crystal structure changes, that is, the phase transformation is almost finished. That is, while the temperature of the steelmaking slag 10 is about 700 ° C. or higher, the steelmaking slag 10 is gradually cooled so as to drop at a rate of 1.0 ° C./min or less. In addition, in order to fully solidify the steelmaking slag 10 so that sufficient crushing in the crushing process performed next is possible, steelmaking over 24 to 30 hours or longer than that depending on the outside air temperature. It is preferable to cool the slag 10.

On the other hand, when the temperature of the steelmaking slag 10 is about 700 ° C. or higher, the temperature of the steelmaking slag 10 is lowered at a rate exceeding 1.0 ° C./min by increasing the amount of cooling water or spraying the steelmaking slag 10 directly. As a result, a brittle slag having a low internal density is obtained after solidification.
When blast furnace slag is used instead of the steelmaking slag 10, for example, the blast furnace slag after water granulation and quenching forms a vitreous slag containing almost no pores.

By gradually cooling the steelmaking slag 10 as described above, when the steelmaking slag 10 is solidified, it is included in the steelmaking slag 10 and can cause a hydration reaction, such as free CaO, MgO, or a soft compound such as these compounds. And a hard mineral phase with high density (formed from silica [SiO ₂ ], alumina [Al ₂ O ₃ ], etc.) form different layers separated from each other. Actually, most of these mineral phases are in solid solution in two or more of CaO, MgO, SiO ₂ and Al ₂ O ₃ , but they are soft and hard due to cooling at the above cooling rate. Minerals are formed. For this reason, when the steelmaking slag 10 after solidification is subjected to a crushing process described later, many of the hard mineral phases are separated from each other into a lump by fine crushing of the soft portions between the mineral phases, and this lump When the mineral phase is crushed, it becomes sandy. And in the steelmaking slag 10, since it is mainly comprised by the soft part which is pulverized by crushing, there is little quantity pulverized.

The steelmaking slag 10 that has been solidified in the cooling step 2 and whose temperature has been sufficiently lowered is discharged from the slag pan and sequentially subjected to crushing by the jaw crusher crushing treatment 31 and the rod mill crushing treatment 32 constituting the slag beneficiation treatment step 3. .
In the jaw crusher crushing process 31, the steelmaking slag 10 is sandwiched and pressed between the fixed teeth in the jaw crusher and the movable teeth movable so as to approach and leave the fixed teeth in the air. Compression crushing. The steelmaking slag 10 is roughly dry crushed by this treatment. At this time, in the steelmaking slag 10, the mineral phase is separated into a large number of masses by the collapse of the soft portion layer such as CaO between the hard mineral phases.

In the rod mill crushing process 32 after the jaw crusher crushing process 31, the steelmaking slag 10 is put into a rod mill containing water inside and put in water, and the rod mill is rotated to further finely wet crush. Is done. In this wet crushing process, soft CaO or the like contained in the steelmaking slag 10 becomes fragile by a hydration reaction, and is crushed into a fine powder and suspended in water. Moreover, the massive hard mineral phase contained in the steelmaking slag 10 is crushed into grains having an angular shape in a rod mill, and a powdery body generated from the mineral phase during suspension is suspended in water. Note that sand formed by grains having an angular shape contributes to compaction more than sand formed by grains having a smooth surface.
In the process of receiving the above two crushing treatments, the metal 15 contained in the steelmaking slag 10 is separated from the slag composed of components such as mineral phases and fine powders such as CaO. And since the steelmaking slag 10 has fully solidified by the cooling process 2, separation | separation with the metal 15 and slag at the time of a crushing process becomes easy.

  The steelmaking slag 10 that has completed the crushing process is subjected to the specific gravity beneficiation process 33 constituting the slag beneficiation process 3. In the specific gravity beneficiation process 33, the steelmaking slag 10 is thrown into the treated water, and sorting is performed using a specific gravity difference by a specific gravity sorter. In the steelmaking slag 10, those selected as having a high specific gravity are subsequently subjected to a magnetic separation process 34, and those selected as having a low specific gravity are subsequently subjected to a sieve classification process 35. Here, the magnetic separation process 34 and the sieve classification process 35 constitute a slag separation process 3.

In the magnetic separation process 34, the metal 15 is separated and collected by the magnetic separator with respect to the steelmaking slag 10 having a high specific gravity including the metal 15.
Further, in the sieve classification treatment 35, the low specific gravity steelmaking slag 10 taken out from the specific gravity sorter and contained in the treated water is supplied onto a vibrating screen (sieve) of the vibration sieve, Those having a mesh size (5 mm in this embodiment) or less are selected. The steelmaking slag 10 having a particle diameter of more than 5 mm that has not passed through the screen is returned to the rod mill crushing process 32 together with the treated water in which it is contained, and is subjected to a wet crushing process.

  The steelmaking slag 10 having a particle diameter of 5 mm or less that has passed through the screen is in a sand slime state in which the sand granular particles, fine powder particles, and treated water are mixed, and is subjected to the Akins classification process 36 to separate the granular components. That is, the steelmaking slag 10 contained in the treated water is sent to an Aikens classifier that is a spiral type classifier together with the treated water, and is subjected to classification, thereby obtaining particles having a specific particle size (about 0.15 mm) or more. The portion is separated from the powdery portion suspended in water and selected as coarse sandy slag 12. Thereby, this sandy slag 12 is comprised with the particle size of 0.15 mm or more and 5 mm or less.

  The steelmaking slag 10 after the sandy slag 12 is removed is in a slime state in which the fine powdery particles and the treated water are mixed, and the fine powdery particles are separated from the treated water after receiving the thickener / dehydration treatment 37. The In this process, the steelmaking slag 10 contained in the treated water is sent to a thickener together with the treated water and subjected to classification, and the steelmaking slag 10 composed of fine powder particles is separated from the slime. Furthermore, the steelmaking slag 10 separated in a state containing moisture is subjected to a dehydration process and recovered as cake-like powdered slag 11. Here, the Akins classification process 36 and the thickener / dehydration process 37 constitute a slag beneficiation process 3.

And sandy slag 12 obtained by the above-mentioned Akins classification process 36 is porous crystalline, and has the hydraulic property which reacts with water and hardens when time passes in the presence of moisture. Further, the sandy slag 12 has a particle size range of 0 to 5 mm, a fine particle amount of 3.5% or less, a coarse particle ratio of 3.5% or less, and a water permeability of 5.0 × 10 ^{−3 to} 2.0 × 10 ⁻² cm. / S (cm / sec), unit volume mass of 1.9 to 2.1 kg / L (liter), and water absorption of 1.5 to 3.2%. Furthermore, the porous sandy slag 12 has a volume content (porosity) of pores having a diameter of 0 to 120 μm of 10 to 20%. Moreover, the sandy slag 12 has the characteristic that the elution amount with respect to the water of F is less than 0.8 mg / L. In addition, the range of less than 0.8 mg / L of elution amount with respect to the water of F satisfies the soil environment standard.

  The fine particle amount can be determined by the fine particle amount test method specified in JIS A 1103, and the coarse particle ratio can be determined by the aggregate screening test method (particle size distribution test method) specified in JIS A 1102. it can. The porosity was measured by applying a mercury intrusion method to the dried sandy slag 12 in a pore diameter measurement range of 0.005 to 120 μm using a mercury porosimeter such as Micromeritec Autopore III 9400 manufactured by Shimadzu Corporation. Can be measured. Mercury porosimeters measure the amount of mercury intrusion at each pressure step while gradually increasing the injection pressure based on the relationship between the mercury injection pressure into the pores of the sandy slag and the pore diameter. The distribution of the pore diameter is obtained.

  The sandy slag 12 can ensure strength and water permeability by adjusting the porosity of the pores having a diameter of 0 to 120 μm to 10 to 20%. The sandy slag 12 becomes brittle as the pores contained therein become larger, and cannot provide the required strength when used as a roadbed material or a paving material. Moreover, when the sand-like slag 12 has a porosity of less than 10%, water permeability cannot be ensured, and when it has a porosity of more than 20%, strength cannot be ensured. Incidentally, when the sand-like slag 12 is formed from stainless steel slag, the sand-like slag 12 having the above-mentioned characteristics can be efficiently generated by slow cooling and crushing as described above.

Further, powdery slag 11 obtained after the dehydration process, rich in CaO and SiO _2, with a hydraulic that is cured by reacting the time in the presence of moisture has passed the water. Furthermore, the powdery slag 11 has the characteristics that the particle size range is 0 to 0.7 mm, the ratio of the particle size of 450 μm or less is 95 mass% or more, and the specific surface area is 1700 branes or more.

  Referring to FIG. 2, a part of the obtained powdered slag 11 is subjected to a granulation treatment 41 constituting the granulation step 4. In the granulation process 41, the powdered slag 11 is put into a granulator such as an Eirich mixer or a rotary cylinder mixer together with the standard cement 16 and the coal ash 17 and mixed while receiving the addition of water. As a result, the powdered slag 11 is agglomerated and hardened together with the cement 16 and the coal ash 17 to form the granulated slag 13. In this mixing process, the powdery slag 11 is contained in a total content of 100% of the powdered slag 11 + cement 16 + coal ash 17 at a content of 60 to 85% by mass, and the cement 16 is contained in an amount of 5 to 20% by mass. The coal ash 17 is contained at a content of 10 to 35% by mass. Furthermore, water is added at a rate as an external number of 15 to 25% by mass with respect to 100% of the total mass of powdered slag 11 + cement 16 + coal ash 17.

  The blending of the powdered slag 11, the cement 16 and the coal ash 17 is determined so that unreacted CaO does not remain at the end of the solidification reaction that forms the granulated slag 13. This is because CaO expands due to a hydration reaction, so that unreacted CaO creates a risk of expanding and collapsing the granulated slag 13, that is, causing disintegration.

Therefore, the content of the powdery slag 11 is set to 60 to 85% by mass. When the content rate of powdery slag 11 exceeds 85 mass%, the compounding quantity of cement 16 and coal ash 17 will reduce, and excess CaO contained in powdery slag 11 may remain, and it may produce disintegration. Incidentally, coal ash, rich in SiO ₂ having reactivity with CaO. On the other hand, when the content rate of powdery slag 11 will be less than 60 mass%, the compounding quantity of the cement 16 and the coal ash 17 will increase, and cost will be raised.

  Furthermore, the content rate of the cement 16 is 5 to 20% by mass. When the content of the cement 16 is less than 5% by mass, the granulated slag 13 cannot obtain the required strength. On the other hand, when the content of the cement 16 exceeds 20% by mass, the cost increases, and in some cases, the blending ratio of the coal ash 17 is lowered and the disintegration property may be deteriorated. Furthermore, since the cement contains hexavalent chromium, the content of hexavalent chromium in the granulated slag 13 increases, and the soil environment standard may not be satisfied.

Furthermore, the content rate of the coal ash 17 is 10-35 mass%. The purpose of blending the coal ash 17 is to use it as a supply source of SiO ₂ and Al ₂ O ₃ that are subjected to a pozzolanic reaction with CaO as a component of the powdered slag 11. For this reason, in order to balance the CaO content of the powdery slag 11 and the supply amounts of SiO ₂ and Al ₂ O ₃ , the blending ratio of the coal ash 17 is determined. Since the content rates of SiO ₂ and Al ₂ O ₃ differ depending on the type of coal ash, the content rate of coal ash 17 is 10 in consideration of the component ratio from the general incineration ash to the combustion ash of a special pressurized fluidized bed. It will be -35 mass%. When the content of the coal ash 17 is less than 10% by mass, the granulated slag 13 cannot be prevented from collapsing even if the proportion of the powdered slag 11 is reduced and the proportion of the cement 16 is increased. On the other hand, when the content rate of the coal ash 17 exceeds 35 mass%, granulation property will deteriorate. This is because coal ash has very poor granulation properties compared to slag due to its physical properties such as particle shape and specific gravity.

  Moreover, the addition rate of water shall be 15-25 mass%. Water is necessary for developing the strength by blending the three raw materials of powdered slag 11, cement 16, and coal ash 17, but has a great influence on the particle size control during granulation. When the water addition rate is less than 15% by mass, the solidification reaction of the cement 16 becomes insufficient, and the powdered slag 11 cannot be grown in a granular form. If the addition rate of water exceeds 25% by mass, the water content becomes excessive, and the powdered slag 11 becomes a clay-like or cocoon-like huge lump, making granulation impossible. The addition rate of water said here means the quantity including the water which slag originally contains.

  Referring again to FIG. 2, when the granulated slag 13 formed in the granulator is taken out of the granulator, the predetermined curing period in which the solidification reaction is completed and the required strength is developed. It is cured 42 in the atmosphere. In addition, since the granulated slag 13 is formed from steelmaking slag, it has a high solidification speed.

The granulated slag 13 after elapse of a predetermined curing period is subjected to a sieve classification process 43. In the sieving classification process 43, the granulated slag 13 is supplied onto the vibrating sieve of the vibration sieving machine, and those having a size of the sieve opening (40 mm in the present embodiment) or less are selected and lump-shaped. It moves to the mixing process which comprises the following mixing process 5 as the slag 14. FIG. In addition, the granulated slag 13 exceeding the particle diameter of 40 mm that has not passed through the sieve is transferred to the crushing process 44 and subjected to a dry crushing process using a dry mill or the like. The granulated slag 13 that has been subjected to the crushing process 44 is again subjected to the sieving and classifying process 43, and those having a particle size of 40 mm or less are transferred to the mixing process as a massive slag 14, and those having a particle diameter exceeding 40 mm are transferred to the crushing process 44 again. .
The bulk slag 14 having a particle size of 40 mm or less is formed through a series of granulation steps 4 including the granulation process 41, the curing process 42, the sieve classification process 43, and the crushing process 44 described above.

  In the mixing process of the mixing step 5, the massive slag 14 and the powder are mixed at a blending ratio of 28 to 56% by mass of the massive slag 14, 8 to 21% by mass of the powdered slag 11, and 30 to 60% by mass of the sandy slag 12. The slag 11 and the sand slag 12 are put into a stirring device such as a paddle mixer and mixed. Or you may mix with heavy machines, such as a power shovel and a wheel loader. As a result, a roadbed pavement material 100 that can be used as a roadbed material and a pavement material is generated. The generated roadbed pavement material 100 is stored in a storage yard and shipped according to demand (storage / shipping 6).

The generated roadbed pavement material 100 has characteristics of a water permeability coefficient of 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻³ cm / s and a water immersion expansion ratio of 0.3% or less. Furthermore, the roadbed pavement material 100 has a good compactability because the corrected CBR value, which is an index indicating the quality standard of the compactness of the roadbed material and the embankment material, is in the range of 80 to 200%. In the “Pavement Handbook” from the Japan Road Association, the corrected CBR value required for the lower layer roadbed material is 30% or more, and the corrected CBR value required for the upper layer roadbed material is 80% or more. Furthermore, the required water immersion expansion ratio is 1.5% or less for the lower layer roadbed material and the upper layer roadbed material.

(Example)
Hereinafter, the example of the roadbed pavement material 100 manufactured using the manufacturing method of the present embodiment and the comparative example of the roadbed pavement material manufactured using a manufacturing method different from the manufacturing method of the present embodiment will be verified. . In addition, the roadbed paving material of a comparative example is produced | generated by the mixing | blending ratio which remove | deviated from the range of the mixing | blending ratio of the powdery slag, sandy slag, and block slag which were mentioned in this Embodiment.
Moreover, the powdery slag, the sandy slag, and the massive slag constituting the roadbed pavement material of the example and the roadbed pavement material of the comparative example are made using steelmaking slags A and B having two different compositions shown in Table 1 below. Generated.

  And in the following Table 2, about 13 examples and 10 comparative examples, the blending ratio of powdery slag, sandy slag and massive slag, and the respective characteristics (water permeability coefficient, modified CBR, water expansion ratio and rain resistance) Sex). In Examples 1 to 10 and 12 and Comparative Examples 1 to 9, granulated slag having a particle size of 40 mm or less obtained by granulating powdered slag is used as bulk slag. In Examples 11 and 13, Crushed granulated slag having a particle size of more than 40 mm obtained by granulating the slag is used as bulk slag.

The permeability coefficient was measured by an indoor permeability test in which a constant water level permeability test and a variable water level permeability test were appropriately selected.
The corrected CBR value was measured by a laboratory test. Specifically, a specimen adjusted to a water content ratio of ± 1% of the optimum water content ratio obtained by the soil compaction test method by JIS A 1210 tamping is prepared, and JIS A 1211 is used by using this specimen. Based on the compaction curve determined according to the CBR test method and the CBR-dry density relationship diagram, a corrected CBR value corresponding to a compaction degree of 95% of the maximum dry density was determined.
The water expansion ratio was measured by a water immersion expansion test method for steel slag as defined in Appendix 2 of “Road Steel Slag” (JIS A 5015).

  The rain resistance was tested as follows. As shown in FIG. 3, the roadbed pavement materials of the example and the comparative example were each laid on the roadbed in the test area so that the finished thickness was 15 cm, and then using a rolling compaction machine (10 t tire roller). Rolling was performed until a predetermined degree of compaction was obtained. One hour after the completion of rolling, a weir frame with a shape surrounding a 1m x 1m square is placed on the compacted surface of the roadbed pavement, and 20 liters of water is poured inside the weir. Accumulated. After 3 hours from the introduction of water, the residual state of water in the weir frame was visually confirmed. If no block water is seen, that is, if the drainage is good, it is judged as good, and if there is a little lump of water left but the roadbed pavement material is not muddy, it is judged as good, and the block water is When the road surface pavement material on the remaining surface was muddy, it was determined to be impossible. This rain resistance represents the surface stability during rainfall after compaction as a roadbed material and the appropriateness as a paving material.

As shown in Table 2, in Examples 1 to 13, the water permeability coefficient is within the range of 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻³ cm / s. Further, for Examples 11 and 12 having the same blending ratio, in Example 12 using granulated slag having a particle diameter of 40 mm or less obtained by granulating powdered slag as massive slag, powdered as massive slag The water permeability coefficient is larger than that of Example 11 using a crushed granulated slag having a particle diameter of more than 40 mm obtained by granulating slag. On the other hand, in Comparative Examples 1 to 6, where the blending ratio of sandy slag is lower than that of the example, the water permeability is less than 1.0 × 10 ⁻⁵ cm / s, and the blending ratio of sandy slag is lower than that of the example. In the high comparative examples 7-10, the water permeability exceeds 1.0 * 10 < ^-3 > cm / s. In the comparative example, the blending ratio of sandy slag greatly affects the hydraulic conductivity of the roadbed pavement material.

In Examples 1 to 13, the corrected CBR value is within the range of 80 to 200%. On the other hand, in Comparative Examples 2 and 4, the corrected CBR value falls within the range of 80 to 200%, and in Comparative Examples 1, 3, and 5 to 8, the corrected CBR value is less than 80%. Moreover, in the roadbed pavement materials of Comparative Examples 9 and 10 that were substantially sand, the corrected CBR could not be measured.
Moreover, in Examples 1-13, a water immersion expansion ratio is 0.3% or less (target value of an internal standard: 0.3% or less), and in Comparative Examples 1-10, a water immersion expansion ratio is 0.3. % Is over. Here, the Japanese Industrial Standard “Steel Slag for Roads” (JIS A 5015) stipulates that the water expansion ratio by the water immersion expansion test method specified in Annex 2 is 1.5% or less. Since the quality is not necessarily sufficient at 1.5% or less, it is set to 0.3% or less, which is more stringent as an in-house standard.

  Moreover, rain resistance is favorable in Examples 1 to 13 and Comparative Examples 8 to 10, impossible in Comparative Examples 1 to 6, and acceptable in Comparative Example 7. In Comparative Examples 7 to 10, since the roadbed pavement has properties close to sand, drainage is good. The roadbed pavement materials of Examples 1 to 13 have good drainage after compaction and do not cause changes in surface properties due to rain or the like. It can function as the surface layer of the road as it is, that is, it can function as pavement as it is by the construction of only pressure. In addition, in the layer formed by compacting the roadbed pavement materials of Examples 1 to 13 with good drainage and water permeability, water due to watering, raining, etc. penetrates sufficiently to the inside. It causes a hydration reaction and cures, increasing the strength of this layer.

  From the above results, the roadbed paving material of the example formed with a blending ratio of 30-60 mass% sandy slag, 28-56 mass% massive slag, and 8-21 mass% powdered slag is Not only can it be used as a material, it can also be used as a paving material.

  Thus, the civil engineering material according to the embodiment of the present invention is a civil engineering material using the steelmaking slag 10 generated in the steelmaking process 1 of stainless steel. The roadbed pavement material 100, which is a civil engineering material, is produced from the steelmaking slag 10 and is produced from the powdered slag 11 in which the ratio of the particle size of 450 μm or less occupies 95% by mass or more and the steelmaking slag 10 and the particle size of 0 to 5 mm. It is generated by mixing the sandy slag 12 in the range of 1 and the massive slag 14 which is a massive aggregate having a particle size of 40 mm or less. At this time, the powdery slag 11, the sandy slag 12, and the massive slag 14 are mixed at a blending ratio of 8 to 21% by mass, 30 to 60% by mass, and 28 to 56% by mass, respectively.

  The roadbed pavement material 100 produced by mixing the powdery slag 11, the sandy slag 12 and the massive slag 14 at the blending ratio as described above has water permeability and good compactability. For this reason, since the ground by the roadbed pavement material 100 after laying and compacting has good drainage, the passage and further construction of the vehicle on the ground can be performed without being affected by rainfall. Therefore, the roadbed pavement material 100 can be used as a roadbed material or a pavement material, and its application can be expanded. And such a roadbed pavement material 100 also makes it possible to construct the roadbed and the pavement as an integral structure. Furthermore, even if the roadbed pavement material 100 having water permeability is shipped in a state of excessive moisture during rainy weather and rainy season, it can be laid and rolled, and the finish is also good. That is, the roadbed pavement material 100 enables construction under a wide range of construction conditions and expands its application.

In addition, after being compacted and solidified, when rainwater or the like falls on the surface of the roadbed pavement material 100, it penetrates into the 100 layer of the roadbed pavement material, whereby the slag-derived alkaline component together with the permeated water 100 It flows out of the layer and is neutralized, adsorbed, etc. by the soil under the 100 layer of the roadbed pavement material. For this reason, at the time of rain, the rainwater flowing out from the 100 layers of the roadbed pavement has a property near the neutrality and has a small influence on the environment. On the other hand, if the pavement material has poor water permeability, high alkaline water that remains on the surface will flow through the surface for some reason and will not be adsorbed by the soil under the pavement material. Since it may be caused and it is dangerous, the pavement work is limited depending on the weather, but the roadbed pavement material 100 can also be shipped when it rains. Furthermore, since the soil of 100 layers of roadbed pavement material contains the adsorbed alkali component, the growth of plants such as weeds from this soil can be suppressed. For this reason, the layer by the roadbed pavement material 100 can reduce costs, such as maintenance management and care.
In addition, by generating at least the powdery slag 11 and the sandy slag 12 from the steelmaking slag 10, the roadbed paving material 100 can improve the solidification rate by the hydration reaction as compared with the case of using blast furnace slag or the like. Can do.

In the roadbed paving material 100, the sandy slag 12 is a porous crystal slag. As a result, the water permeability of the particles of the sandy slag 12 itself is improved, so that the water permeability of the roadbed pavement material 100 can be improved.
Further, the sandy slag 12 has a particle size of 0 to 5 mm, a water permeability coefficient of 5.0 × 10 ^{−3 to} 2.0 × 10 ⁻² cm / s, and a unit of 1.9 to 2.1 kg / liter. By having a volume mass, a water absorption rate of 1.5 to 3.2%, and a pore content rate of 0 to 120 μm in diameter of 10 to 20%, the roadbed pavement material 100 is 1.0 × 10 ^−5. It can have a water permeability coefficient of ˜1.0 × 10 ⁻³ cm / s, a modified CBR value of 80 to 200%, and a water expansion ratio of 0.3% or less. Therefore, the roadbed pavement material 100 can have good characteristics as a roadbed material and a pavement material.

  Moreover, in the said roadbed pavement material 100, the block slag 14 is formed from the granulated slag which granulated powdery steelmaking slag 10, such as the powdery slag 11. FIG. Thereby, the further effective utilization of the steelmaking slag 10 can be aimed at.

Moreover, in the roadbed pavement material 100 of embodiment, although the powdery slag 11 produced | generated from the steel-making steel slag 10 of stainless steel was used as the powdery slag, as a by-product in the manufacturing process of cast iron as a powdery slag You may use what was produced from other steel slag, such as steelmaking slag byproduced in the steelmaking process of blast furnace slag, ordinary steel, and other special steel. In powdered slag, the ratio of the particle size of 450 μm or less may occupy 95% by mass or more.
In the roadbed paving material 100 of the embodiment, sandy slag 12 generated from stainless steel slag 10 is used as sandy slag, but ordinary steel and other special steels are used as sandy slag. You may use what was produced from steelmaking slag of. Sand-like slag has a particle size of 0 to 5 mm, a water permeability of 5.0 × 10 ^{−3 to} 2.0 × 10 ⁻² cm / s, a unit volume mass of 1.9 to 2.1 kg / liter, It is only necessary to have a water absorption of 0.5 to 3.2% and a pore content of 10 to 20% of a diameter of 0 to 120 μm.

  Further, in the roadbed pavement 100 according to the embodiment, the bulk slag 14 obtained by granulating the powdered slag 11 in which the ratio of the particle size of 450 μm or less occupies 95% by mass or more is used as the bulk aggregate. The particle size of the powdery slag constituting 14 is not limited to the ratio of the particle size of 450 μm or less occupying 95% by mass or more. Further, the aggregate is not limited to the one using the steelmaking slag 10 made of stainless steel, but uses other steel slag such as blast furnace slag, steelmaking slag of ordinary steel or other special steel. May be. Alternatively, the aggregate may be crushed stone or granulated material other than slag such as natural stone.

  DESCRIPTION OF SYMBOLS 1 Steelmaking process, 2 Cooling process, 3 Slag beneficiation process, 4 Granulation process, 5 Mixing process, 10 Steelmaking slag, 11 Powdered slag, 12 Sandy slag, 13 Granulated slag, 14 Bulk slag (bulk aggregate) , 100 Roadbed paving material (civil engineering material).

Claims (7)

A civil engineering material using steelmaking slag produced in the steelmaking process,
Powdered slag that is produced from the steelmaking slag and has a particle size of 450 μm or less occupying 95 mass% or more,
Sandy slag produced from the steelmaking slag and having a particle size in the range of 0-5 mm;
It is generated by mixing with aggregates having a particle size of 40 mm or less,
The civil engineering material in which the powdery slag, the sandy slag, and the massive aggregate are mixed at 8 to 21% by mass, 30 to 60% by mass, and 28 to 56% by mass, respectively.   The civil engineering material according to claim 1, wherein the sandy slag is a porous crystal slag. The sandy slag is
A particle size of 0-5 mm,
A water permeability coefficient of 5.0 × 10 ^{−3 to} 2.0 × 10 ⁻² cm / s,
A unit volume mass of 1.9 to 2.1 kg / liter;
1.5-3.2% water absorption,
The civil engineering material according to claim 1 or 2, having a pore content of 10 to 20% and a diameter of 0 to 120 µm. The water permeability is 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻³ cm / s,
The corrected CBR value is 80-200%,
The civil engineering material according to any one of claims 1 to 3, wherein a water expansion ratio is 0.3% or less.   The civil engineering material according to any one of claims 1 to 4, wherein the massive aggregate is formed from granulated slag obtained by granulating the powdered steelmaking slag. In the manufacturing method of the civil engineering material as described in any one of Claims 1-5,
A powdered slag producing step for producing the powdered slag by sequentially performing cooling, crushing, classification and dehydration treatment on the steelmaking slag;
Sand-like slag production step for producing the sand-like slag by sequentially cooling, crushing and classifying the steelmaking slag,
A mixing step of mixing the powdery slag, the sandy slag, and the massive aggregate at the blending ratio.   The method according to claim 6, further comprising the step of granulating the powdered steelmaking slag to adjust the particle size to generate the massive aggregate before the mixing step.

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