JP2002020156A - Roadbed material using steelmaking slag as raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that insufficiency of strength and expansion due to free MgO, of a roadbed material produced by crushing a slag hardened body using steelmaking slag as a part of the raw material, and rise in pH of water in contact with the roadbed material, are caused. SOLUTION: The production process of this roadbed material comprises mixing a mixture which contains granular molten pig pretreatment slag as steelmaking slag and also contains fine powdery blast-furnace slag as an SiO2- containing material, with water, to obtain a mixture and to harden the mixture crushing the resulting hardened body, wherein in the above mixture, on the basis of the total mass of all the components of the mixture, the content of the granular molten pig pretreatment slag having >=1.18 mm grain size is 15-55 mass % and the content of the fine powdery blast-furnace slag is 5-40 mass %, and the pH of water brought into contact with the roadbed material, after the contact, is <=10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roadbed material using a steelmaking slag, particularly a powdery and granular hot metal pre-treated slag which has been difficult to use effectively, and a pH after contact of water with the roadbed material. Road material that does not rise.

[0002]

2. Description of the Related Art Slag generated in the steelmaking process has a high basicity and contains a large amount of free CaO, so that it easily absorbs water and expands, and is not suitable for use as civil engineering and construction materials such as blast furnace slag. The processing is extremely difficult. Therefore, some attempts have been made to actively utilize such steelmaking slag.

[0003] For example, in Japanese Patent Application Laid-Open No. 10-152364, one or two of an aggregate containing steelmaking slag, a silica-containing substance having latent hydraulic property and a silica-containing substance having pozzolanic reactivity are 50%. A hydrated hardened product using a steelmaking slag having the above-mentioned binder and a binder hardened by a hydration reaction is disclosed.

[0004] Another example is disclosed in Japanese Patent Application Laid-Open No. 2-23353.
No. 9 discloses a slag block in which all of the binder, fine aggregate and coarse aggregate are made into crushed and crushed steel slag, and blast furnace slag and steelmaking slag are combined as the binder.

[0005] Regarding the roadbed material using slag, Japanese Patent Application Laid-Open No. 11-21153 discloses Ca (OH) in powdery slag.
A roadbed material is disclosed in which slag is agglomerated using CaCO ₃ obtained by carbonating ₂ as a binder and then crushed.

[0006]

However, the inventor of the present invention made a trial production of a hardened material using steelmaking slag as a raw material in order to develop a roadbed material from which high-pH water does not elute using the above-mentioned conventional technology. The following problems became clear.

First, according to the method disclosed in Japanese Patent Application Laid-Open No. 10-152364, when converter slag is used as steelmaking slag, it collapses during water curing at 20 ° C. and a satisfactory cured product cannot be obtained. was there. After investigating the cause in detail, the MgO concentration in the converter slag has increased due to dolomite and magnesia clinker added to the slag in order to protect the refractory lining of the converter in recent years, It was found that when such converter slag having a high MgO concentration was used, the cured product collapsed due to hydration expansion of free MgO contained in the converter slag during curing in water.

Therefore, the present inventor has found that free M
An attempt was made to use a hot-metal pretreated slag containing no gO, and a slag hardened body was produced in the same manner as described above, but the strength was insufficient, and a material that could withstand use as a roadbed material was not obtained.

On the other hand, in order to produce a hardened slag from converter slag as a raw material by the method described in JP-A-2-233593, it is necessary to finely pulverize the slag. Since the slag itself is hard and hard to turn into fine powder due to the presence of a free MgO phase, there has been a problem that pulverization to a highly reactive fine powder is expensive. In addition, hot metal pretreatment slag containing no free MgO was used, and production of a cured product was attempted in accordance with the composition described in JP-A-2-233593, but the strength was sometimes insufficient, and this was crushed. The obtained material was found to be unsuitable for use as a roadbed material.

[0010] The present invention provides a method for manufacturing a roadbed material by crushing a hardened slag using steelmaking slag as a part of a raw material as described above, which results in insufficient strength, expansion caused by free MgO, and contact water. It is an object of the present invention to provide a roadbed material using steelmaking slag as a raw material, which has solved problems such as a rise in pH at once.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made to achieve the above object, and comprises mixing a mixture mainly composed of a granular steelmaking slag and a SiO ₂ -containing substance having latent hydraulic properties together with water. A roadbed material made of steelmaking slag as a raw material, which is obtained by crushing a hardened material that has been kneaded, hardened, and crushed, wherein the pH of the water after contact with the roadbed material is 10 or less. I will provide a. The reason why the pH after contact of the water in contact with the roadbed material is 10 or less is that a weak alkaline or neutral pH of 10 or less does not adversely affect nearby land and crops.

The roadbed material using such steelmaking slag as a raw material contains, as the mixture, powdery and granular hot metal pretreated slag as steelmaking slag, blast furnace slag fine powder as a SiO ₂ -containing substance, and granules in all components. 1.18mm diameter
It can be manufactured using a mixture in which the content of the following hot metal pretreated slag is 15 to 55% by mass and the content of the blast furnace slag fine powder is 5 to 40% by mass.

[0013] Further, the mixture is powdered as steelmaking slag.
Granulated hot metal pretreatment slag, SiO _TwoHigh as a contained substance
Furnace slag containing fine powder and fly ash
Hot metal pretreatment slurries with a particle size of 1.18 mm or less
15-55% by mass of blast furnace slag
The proportion is 3-36% by mass, and the content of fly ash is 1.
5 to 30% by mass, blast furnace slag content and flyer
Ratio of fly ash content to total ash content
Is manufactured using a mixture having a mass ratio of 0.1 to 0.75.
can do.

The ratio of the content of the hot metal pretreated slag to the sum of the content of the blast furnace slag fine powder, the blended amount of fly ash, and the content of the hot metal pretreated slag having a particle size of 1.18 mm or less is 0 in mass ratio. .2 is preferred.

The mixture further comprises one or more selected from the group consisting of oxides, hydroxides, sulfates and chlorides of alkali metals and / or alkaline earth metals, with the blast furnace slag content It is good also as a mixture which added 0.2 to 20 mass% by mass ratio to the total fly ash content.

Further, the mixture further comprises a naphthalenesulfonic acid and / or a polycarboxylic acid in a mass ratio to the total of the blast furnace slag content, the fly ash content and the content of the hot metal pretreated slag having a particle size of 0.1 mm or less. More preferably, the mixture is added in an amount of 0.1 to 2.0% by mass.

[0017]

Embodiments of the present invention will be described below in detail. First, in the present invention, a hot metal pre-treatment slag is particularly used as a steelmaking slag. The reasons are as follows: (1) Since MgO is not added, MgO concentration is originally low, and CaO / SiO ₂ is low, so MgO slightly contained is almost present as Ca ₂ MgSi ₂ O ₇ . Therefore, there is almost no free MgO phase.
As a result, cracking of the hardened body due to hydration expansion of free MgO, which had conventionally occurred when using converter slag as a raw material,
(2) The free CaO concentration is low because CaO / SiO ₂ is low and the P ₂ O ₅ concentration is high. Therefore,
Hydration swelling due to free CaO is also low, so that problems such as cracking, powdering, deformation, and reduced strength of the hardened body caused by hydration expansion of free CaO in steelmaking slag can be eliminated. In many cases, because of its high reactivity, it can be used as a substitute for blast furnace slag fine powder and fly ash. (4) Since there is almost no free MgO phase, the slag itself is soft, and compared with converter slag. (5) By the action of the hot metal pretreatment slag of the fine powder, the hot metal pretreatment slag easily reacts with the blast furnace slag fine powder and fly ash, resulting in higher strength.

Further, in the present invention, when such a slag for pretreatment of molten iron is used, the
8 mm or less, the content of all the components is 1
It is blended so as to be 5 to 55% by mass. The present inventor has investigated in detail what size of the hot metal pre-treatment slag has a large portion contributing to the hardening reaction, and found that the reactivity is particularly good in the range of a particle size of 1.18 mm or less. It was found that the strength of the cured product obtained in the above was increased. Therefore, in the present invention, included in the hot metal pretreatment slag,
With respect to the portion having a particle size of 1.18 mm or less, the content in the composition is particularly regulated. In addition,
This does not prevent the hot metal pretreatment slag having a larger particle size from being contained in the compounded hot metal pretreatment slag. This is because the molten iron pre-treated slag having a large particle size has a high activity and merely contributes as a binder because it means that the slag was difficult to be pulverized in the pulverization process.

The highest strength can be obtained by blending such a pretreated slag having a particle diameter of 1.18 mm or less with an appropriate amount of a SiO ₂ -containing substance having a latent hydraulic property that reacts with the slag.

As such an SiO ₂ -containing substance having latent hydraulic properties, blast furnace slag fine powder or a mixture of blast furnace slag fine powder and fly ash can be preferably used, and proper content when blast furnace slag fine powder is used alone is preferred. Amount is 5-4
0% by mass. If the content of the hot metal pretreated slag having a particle size of 1.18 mm or less is less than 15% by mass, or if the content of the blast furnace slag fine powder exceeds 40% by mass, the relative SiO 2 content is relatively low.
₂ alkali (or alkaline earth) supply ions curing becomes insufficient bee the strength of the obtained cured product is reduced. On the other hand, when the content of the hot metal pretreated slag having a particle size of 1.18 mm or less exceeds 55% by mass or the content of the blast furnace slag fine powder is less than 5% by mass, CaO having hydration expandability in the hot metal pretreated slag is used. SiO to fix the components of
₂ tends to be insufficient, so that the cured product expands and powders in the process of curing the obtained cured product in water, resulting in a significant decrease in strength.

When a mixture of fine powder of blast furnace slag and fly ash is used as the SiO ₂ -containing substance having latent hydraulic properties, the appropriate content is 15 to 15% of the pre-treated slag of molten iron having a particle size of 1.18 mm or less. The content is 55% by mass, the content of blast furnace slag fine powder is 3 to 36% by mass, and the content of fly ash is 1.5 to 30% by mass. It is necessary that the ratio of the fly ash content to the total of the blast furnace slag content and the fly ash content is 0.1 to 0.75 in terms of mass ratio.

The reason for limiting the content of the slag of pre-treated hot metal having a particle size of 1.18 mm or less is as described above. Like the blast furnace slag fine powder, a material containing latent hydraulic SiO ₂ is fly ash, which is fly ash generated by burning coal. Fly ash itself is extremely fine powder, and by using it as a substitute for blast furnace slag, reactivity with hot metal pre-treatment slag is further improved. The effect is remarkable especially when the content is 1.5% by mass or more and the ratio of the fly ash content to the total of the blast furnace slag content and the fly ash content is 0.1 or more in terms of mass ratio. . However, fly ash has a tendency to be inferior in hardenability at room temperature to blast furnace slag fine powder, and the content of fly ash exceeds 30% by mass, or the content of fly ash relative to the total of blast furnace slag content and fly ash content The ratio of the amounts is 0.
If it exceeds 75, the curing of the cured product as a whole will be delayed, which is not preferable. Therefore, its content is
The mass ratio of the fly ash content to the total of the blast furnace slag content and the fly ash content is 1.5 to 30% by mass and the mass ratio is 0.1 to 0.75.

In the present invention, more preferably, the content of the hot metal pretreated slag to the total of the content of the blast furnace slag fine powder, the blended amount of fly ash, and the content of the hot metal pretreated slag having a particle size of 1.18 mm or less is included. Is greater than 0.2 in terms of mass ratio. By defining the content in such a range, the amount of alkali (or alkaline earth) ions supplied from the hot metal pretreatment slag and the quantitative balance of the reactive SiO ₂ in the SiO ₂ -containing substance having latent hydraulicity are balanced. This is because it becomes more appropriate.

The low pH of water eluted from the cured product obtained according to the present invention is because the cured product according to the present invention has 3CaO. SiO ₂ or 2CaO. This is because there is little SiO _{2 and the} like, and alkali elution hardly occurs.

According to the present invention, the effect of improving the strength can be obtained by the above-mentioned compounding. In addition to the above, oxides and hydroxides of alkali metals and / or alkaline earth metals, One or two or more selected from sulfates and chlorides are added in an amount of 0.2 to 20% by mass based on the total blast furnace slag content and fly ash content, or naphthalenesulfonic acid and And / or the polycarboxylic acid is added in an amount of 0.1 to 2.0% by mass based on the total mass of the blast furnace slag content, fly ash content, and hot metal pretreatment slag content having a particle size of 0.1 mm or less. Good.

Curing by adding 0.2% by mass or more of one or more selected from oxides, hydroxides, sulfates and chlorides of alkali metals and / or alkaline earth metals It is possible to accelerate the hardening of the body and shorten the time required for curing. However, 2
Even if added in excess of 0% by mass, the effect is saturated,
The upper limit is 20% by mass.

The addition of naphthalene sulfonic acid and / or polycarboxylic acid improves the kneading properties when the raw materials are kneaded with water. Therefore, the amount of water required for kneading can be reduced, and as a result, a cured product having higher strength can be obtained. At that time, the effect is poor when the addition amount is less than 0.1% by mass with respect to the total of the blast furnace slag content and the fly ash content, and the effect is poor, and 2.0% by mass.
If the amount exceeds 0.1, the effect is saturated.
It was limited to 0% by mass.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

Example 1 As mixed ingredients, pulverized molten iron pre-treated slag, blast furnace slag fine powder pulverized to a particle size of 0.1 mm or less, and C
The mixture was kneaded with water using a (OH) ₂ or without Ca (OH) ₂ , was driven into a mold, and was cured in water at 20 ° C. to produce a hardened material for a roadbed material. Table 1 shows the content of each raw material in the formulation and the amount of kneading water added. Table 1 shows the mixing ratio of each raw material, the strength after curing for 28 days, the specific gravity of the surface dryness, and the strength after 91 days curing of the obtained cured product. The results are shown in Table 2 (Example No. 1).
1-3, 7, 15).

Example 2 Pre-treated slag of hot metal pulverized as a compounding raw material, having a particle size of 0.
Blast furnace slag fine powder pulverized to 1 mm or less, fly ash (particle diameter 0.1 mm or less) and Ca (OH) ₂ or NaOH are kneaded with water and poured into a mold, which is cured in water at 20 ° C. Thus, a hardened material for a roadbed material was manufactured. Table 1 shows the content of each raw material in the formulation and the amount of kneading water added.
Table 2 shows the mixing ratio of each raw material, the strength of the obtained cured product after curing for 28 days, the specific gravity of the surface dryness, and the strength after curing for 91 days (Examples Nos. 4 to 6, 8 to 10; 17).

Example 3 Pre-treated hot metal slag pulverized as compounding raw material, particle size
Blast furnace slag fine powder finely pulverized to 1 mm or less, fly ash (particle diameter 0.1 mm or less) is added to some of them, and Ca (OH) _{2 and} other additives are kneaded with water and placed in a mold. This was cured in water at 20 ° C. to produce a hardened material for a roadbed material. Table 1 shows the content of each raw material in the formulation and the amount of kneading water added. Table 1 shows the mixing ratio of each raw material, the strength after curing for 28 days, the specific gravity of the surface dryness, and the strength after 91 days curing of the obtained cured product. The results are shown in Table 2 (Example No. 1).
11-14, 16, 18).

Comparative Example Aggregate and Portland cement were kneaded together with water as mixing raw materials, poured into a mold, and cured in water at 20 ° C. to produce a hardened material for a roadbed material. Table 3 shows the content of each raw material in the blend, the amount of kneading water added, and the strength of the obtained cured product after curing for 28 days. Table 4 shows the compositions of the hot metal pretreatment slag and converter slag used in the above Examples and Comparative Examples.

Table 5 shows the measurement results of the unit volume mass and the modified CBR of the roadbed material prepared by subjecting the cured product obtained by the present invention to crushing treatment. The crushed cured product of the present invention was able to satisfy the required performance of the roadbed material. Further, the crushed material of the roadbed material and the concrete waste material of the present invention were respectively placed in containers without lids, left outdoors in rainy weather, collected, and the solid matter was filtered to measure the pH of water. The results are shown in Table 6. At this time, the rainwater was almost the same volume as the solid. It was found that the water in contact with the roadbed material obtained by the present invention had a lower pH than the water in contact with the concrete waste material, and was more environmentally preferable. Also, in Example No. Table 7 shows the results of an investigation of cracks in the roadbeds where 1, 8, 18 and the comparative example were compacted.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

[Table 5]

[0039]

[Table 6]

[0040]

According to the present technology, a high-strength cured product can be obtained and can be used as a roadbed material. Furthermore, the pH of the water in contact with the cured product according to the present invention is low. Therefore, the present invention largely contributes to the reuse of resources, improvement of environment, and the like.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Fumio Kogiku 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba In the Technical Research Institute of Kawasaki Steel Co., Ltd. (72) Inventor Hisahiro Matsunaga 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Address Kawasaki Steel Corporation Technical Research Institute (72) Inventor Masato Kumagai 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Kawasaki Steel Corporation Technical Research Center F-term (reference) 4G012 PA27 PA29

Claims (6)

[Claims] 1. A roadbed material obtained by kneading a mixture mainly composed of a granular steelmaking slag and a SiO ₂ -containing substance having latent hydraulic properties with water, curing the mixture, and crushing a cured cured product, PH after contact with water in contact with the roadbed material is 10
A roadbed material made of steelmaking slag, characterized in that: 2. The mixture contains pre-treated hot metal slag as a steelmaking slag and blast furnace slag fine powder as a SiO ₂ -containing substance, and has a particle diameter of 1.1 in all components.
The content of hot metal pre-treatment slag of 8 mm or less is 15 to 55
The roadbed material using steelmaking slag as a raw material according to claim 1, wherein the content of the blast furnace slag fine powder is 5 to 40% by mass. 3. The mixture contains a pre-treated hot metal slag as a steelmaking slag, a blast furnace slag fine powder and fly ash as SiO ₂ -containing substances, and a hot metal reserve having a particle size of 1.18 mm or less in all the components. The content of the treated slag is 15 to 55% by mass, the content of the blast furnace slag fine powder is 3 to 36% by mass, and the content of the fly ash is 1.5 to
The steelmaking slag according to claim 1, wherein the mass ratio of the fly ash content to the total of the blast furnace slag content and the fly ash content is 0.1 to 0.75 at 30% by mass. Roadbed material made from 4. The mass ratio of the content of the hot metal pre-treated slag to the total of the content of the blast furnace slag fine powder, the content of the fly ash and the content of the hot metal pre-processed slag having a particle size of 1.18 mm or less is expressed as a mass ratio. The roadbed material using the steelmaking slag as a raw material according to claim 2 or 3, wherein the value is more than 0.2. 5. The blast furnace slag further comprises one or more selected from the group consisting of alkali metal and / or alkaline earth metal oxides, hydroxides, sulfates and chlorides. The roadbed material made from steelmaking slag according to any one of claims 2 to 4, wherein the mixture is a mixture in which 0.2 to 20% by mass is added in a mass ratio to the total amount of the fly ash and the amount of fly ash. 6. The mixture further comprises a naphthalene sulfonic acid and / or a polycarboxylic acid in a mass ratio to the total of the blast furnace slag content, the fly ash content, and the total content of the hot metal pre-treated slag having a particle size of 0.1 mm or less. At 0.1
A roadbed material made from steelmaking slag as a raw material according to any one of claims 2 to 5, wherein the mixture is a mixture containing -2.0 mass%.