JP2001323403A - Road pavement slab using mill slag as raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a road pavement slab using mill slag as a part of raw material, solving the problems such as insufficient strength, occurrence of cracks, expansion due to free MgO, pH rising of contact water. SOLUTION: This road pavement is formed by mixing with water a mixture containing granular hot metal preliminary treated slag as mill slag and blast furnace slag fine powder as SiO2-containing material, whose percentage of a content of hot metal preliminary treated slag having a particle diameter of 1.18 mm or less is 15 to 55 mass %, and whose percentage of a content of blast furnace slag fine powder is 5 to 40 mass %. The pH of the contact water is 10 or less after contact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road paving slab using steelmaking slag, in particular, a pre-treated slag of hot metal powder which has been difficult to use effectively, and in particular to reduce cracks as much as possible. The present invention relates to a road pavement plate in which the pH after contact with water in contact with the pavement plate does not increase.

[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. For example, JP-A-10-1
In Japanese Patent No. 52364, one or two of an aggregate containing steelmaking slag, a silica-containing substance having latent hydraulic property and a silica-containing substance having pozzolan reactivity are used.
There is disclosed a hydrated hardened product utilizing steelmaking slag having a binder hardened by a hydration reaction containing 0% or more.

[0003] 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 a blast furnace slag and a steelmaking slag are combined as the binder.

[0004]

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

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.

Accordingly, the present inventor has proposed that free M
An attempt was made to use hot metal pretreated slag containing no gO, and a slag hardened body was produced in the same manner as described above. The slag had a compressive strength of less than 20 N / mm ² and could be used as a substitute for cement and concrete. 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, a hot metal pretreatment slag containing no free MgO was used, and the production of a cured product was attempted in accordance with the composition described in JP-A-2-233593. However, the strength was insufficient and many cracks occurred. For example, it was found that the use as a road pavement plate could not be fully used.

The present invention relates to a method for producing a hardened slag using a steelmaking slag as a part of a raw material as described above, in which strength is insufficient, cracks are generated, expansion caused by free MgO, pH of contact water is increased, and the like. It is an object of the present invention to provide a road pavement slab using a hardened slag that has solved the above problems at once.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and it is an object of the present invention to provide a steelmaking slag in the form of powder and steel.
In a road pavement slab formed by kneading a mixture containing an iO ₂ -containing substance as a main component together with water, a pH of the steelmaking slag after contact of the water in contact with the pavement slab is 10 or less. We propose a road pavement version. The reason why the pH after contact of the water in contact with the pavement plate was 10 or less was 10
The following will not adversely affect nearby land and crops. Although the lower limit depends on the raw water, the lower limit is not pH 7 but pH 7 or more.

[0010] Such a road paving slab is a flat precast block slab manufactured at a factory, which is laid on a roadbed to form a surface layer of a road, or a joint cutoff provided on a roadbed at a site. Any of the on-site construction slabs in which a kneaded fluid material is poured into a frame in a flat plate shape and cured. The pavement formed by a rectangular parallelepiped laid on a sidewalk or a park or a small block having a shape similar to this is hardly a paved slab in a narrow sense. To be included in the category of paved version.

In the above-mentioned road paving slab made of steelmaking slag as a raw material, the mixture contains powdered and granular hot metal pre-treated slag as steelmaking slag and blast furnace slag fine powder as a SiO ₂ -containing substance. 1.18
It can be manufactured using a mixture in which the content of hot metal pretreated slag of not more than mm is 15 to 55% by mass and the content of blast furnace slag fine powder is 5 to 40% by mass.

[0012] 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, and the blast furnace slag fine powder content and
Fly ash content relative to the total ash content
A mixture in which the ratio of the amounts is 0.1 to 0.75 by mass is used.
Can be manufactured.

In this case, the particle size is 1.18 mm with respect to the total 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.
The ratio of the content of the following hot metal pre-treatment slag is 0.
It is preferred that it be more than 2.

The mixture may further comprise an alkali metal and / or
Or one or more selected from the group consisting of alkaline earth metal oxides, hydroxides, sulfates and chlorides,
It is good also as a mixture which added 0.2-20 mass% in the mass ratio with respect to the total of blast furnace slag fine powder content and fly ash content.

Further, the mixture further comprises a naphthalene sulfonic acid and / or a polycarboxylic acid in a mass ratio with respect to the total of the blast furnace slag content, the fly ash content, and the hot metal pretreatment slag content having a particle size of 0.1 mm or less. With 0.
A mixture containing 1 to 2.0% by mass may be used.

[0016]

Embodiments of the present invention will be described below in detail.
I will explain it. First, in the present invention, particularly as steelmaking slag
It uses hot metal pretreatment slag. The reason
To explain, the hot metal pre-treatment slag is (1) MgO added
Originally, the MgO concentration is low and CaO /
SiO _TwoMgO is slightly contained because of low C content.
a_TwoMgSi_TwoO₇Exists as Therefore, free M
There is almost no gO phase. As a result, the conventional converter
Of free MgO generated when
Cracking, powdering, deformation, and reduced strength of the cured product due to hydration expansion
(2) CaO /
SiO_TwoIs low and P_TwoO_FiveDue to the high concentration, free C
Low aO concentration. Therefore, hydration swelling due to free CaO
Hydration of free CaO in steelmaking slag due to low tonicity
Such as cracking, powdering, deformation,
(3) a lot of fine powder,
Due to its high reactivity, blast furnace slag powder itself,
(4) Free MgO as an alternative to liash
Slag itself is soft because there is almost no phase
It is much easier to crush than converter slag,
And (5) Hot metal pretreatment of fine powder
Blast furnace slag fine powder, fly ash and
Is more responsive and has higher strength.

Further, in the present invention, when using such a slag for pre-treatment of hot metal, of which
A portion of 8 mm or less is blended so that the content in all blended components except water is 15 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 and the occurrence of cracks was significantly reduced. 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. Hot metal pretreated slag having a large particle size means that it was difficult to be pulverized in the pulverization process, and because it has strength itself, it can contribute as an aggregate or a bulking agent.

The highest strength can be obtained by mixing such a pretreated metal slag having a particle size of 1.18 mm or less with an appropriate amount of a reactive SiO ₂ -containing substance.

The reactive SiO ₂ -containing substance preferably has latent hydraulicity or pozzolanic reactivity. Specifically, blast furnace slag fine powder or a mixture of blast furnace slag fine powder and fly ash Can be preferably used, and the appropriate content when the blast furnace slag fine powder is used alone is 5 to 40% by mass. When 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 the content of the blast furnace slag fine powder is more than 40% by mass, alkali (or alkaline earth) which relatively hardens SiO _2. The supply of ions tends to be insufficient, and the strength of the obtained cured product decreases. 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. The amount of SiO ₂ for fixing the component tends to be insufficient, so that the cured product expands or powders in the process of curing the obtained cured product in water, resulting in a significant decrease in strength.

When a mixture of blast-furnace slag fine powder and fly ash is used as the SiO ₂ -containing substance having latent hydraulic properties, the appropriate content is 15 to 18% of the molten iron pretreatment slag 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. And the ratio of the fly ash content to the total of the blast furnace slag fine powder content and the fly ash content is 0.1 to 0.7 in mass ratio.
5 is required.

The reasons for limiting the content of the slag of pre-treated hot metal having a particle size of 1.18 mm or less are as described above. Fly ash, which is fly ash generated by the combustion of coal, is a substance containing SiO ₂ having the same reactivity as blast furnace slag fine powder. Fly ash itself is extremely fine powder, and by using it as an alternative to blast furnace slag fine powder, reactivity with hot metal pre-treatment slag is further improved, crack generation is suppressed, and strength after prolonged curing is improved. Can be 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 fine powder content and the fly ash content is 0.1 or more in terms of mass ratio. It is. However, the curability of fly ash at room temperature tends to be inferior to that of blast furnace slag fine powder, and the content of fly ash exceeds 30% by mass, or the fly ash relative to the total content of blast furnace slag fine powder and fly ash If the ratio of the ash content exceeds 0.75 in mass ratio, the curing of the entire cured product is delayed, which is not preferable. Therefore, the content is 1.5 to 30% by mass.
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 to 0.75 in terms of mass ratio.

In the present invention, more preferably, the content of the blast furnace slag fine powder, the blending amount of fly ash and the particle size are as follows.
The ratio of the content of the hot metal pre-treated slag having a particle size of 1.18 mm or less to the total content of the hot metal pre-treated slag of 18 mm or less is more 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 reactivity S in the SiO ₂ -containing substance having latent hydraulic properties are determined.
This is because the quantitative balance of iO ₂ becomes more appropriate and the effect of preventing cracking is enhanced.

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 above-mentioned composition can provide an effect of improving strength and remarkably reducing the occurrence of cracks. In addition to this, in addition to the oxidation of alkali metals and / or alkaline earth metals, , A hydroxide, a sulfate, a chloride, 0.2 to 20% by mass in a mass ratio to the total of the blast furnace slag fine powder content and the fly ash content. Naphthalene sulfonic acid and / or polycarboxylic acid are added in a mass ratio of 0.1 to the total of the blast furnace slag fine powder content, the fly ash content, and the hot metal pretreated slag content having a particle size of 0.1 mm or less. To 2.0% by mass.

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, the effect is saturated even if it is added in excess of 20% by mass, so the upper limit is 20% by mass.

The addition of naphthalenesulfonic 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 amount of addition 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 saturated even if added in excess of 2.0% by mass. Therefore, the content was limited to 0.1 to 2.0% by mass.

[0027]

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
a (OH) ₂ was kneaded with water and poured into a mold, which was cured in water at 20 ° C. to produce a cured product. Table 1 shows the content of each raw material in the blend and the amount of kneading water added. Table 2 shows the raw material mixing ratio, the strength of the obtained cured product after 28 days of curing, the specific gravity of the surface dryness, the number of surface cracks, and the strength after 91 days of curing.

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-up
(Particle diameter 0.1mm or less) and Ca (OH) _TwoThe water and
Knead them together, pour them into a mold, and cultivate them in 20 ° C water.
The raw material was cured to produce a cured product. Inclusion of each ingredient in the formulation
Table 1 shows the amounts and the amounts of kneading water added. Raw material mixing ratio, obtained
Strength, surface dry specific gravity, surface after curing for 28 days
Table 2 shows the number of cracks and the strength after curing for 91 days.

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 poured into a mold. This was cured in water at 20 ° C. to produce a cured product. Table 1 shows the content of each raw material in the blend and the amount of kneading water added. Table 2 shows the raw material mixing ratio, the strength of the obtained cured product after 28 days of curing, the specific gravity of the surface dryness, the number of surface cracks, and the strength after 91 days of curing.

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 cured product. Table 3 shows the content, ratio, and addition amount of kneading water for each raw material in the blend. 2 of the obtained cured product
8 days after curing, surface dry specific gravity, number of surface cracks,
The strength after 91 days of curing is also shown in Table 3. Table 4 shows the compositions of the hot metal pretreatment slag and the converter slag used in the above examples.

In each of the examples of the present invention, there were 0.4 cracks.
/ Cm^TwoLess, with extremely small cracks and abrasion resistance
No problem of cracking or chipping during handling or handling
Was. Especially the content of blast furnace slag fine powder and fly ash
Hot metal pretreatment slag with a blending amount and particle size of 0.425 mm or less
Hot metal with a particle size of 0.425 mm or less based on the total content of iron
The ratio of the content of pretreated slag (the ratio shown in C in the table) is
Examples 2, 3, 5 to 7, 1 in which the quantitative ratio is more than 0.27
For 2-14 and 17-18, the number of cracks is 0.2 / c
m^TwoThe following is preferable because it is further reduced. Also, blast furnace slag
Content of fine powder, blending amount of fly ash and particle size of 0.
For the total content of hot metal pre-treated slag of 1 mm or less
Of hot metal pre-treatment slag with a particle size of 0.1 mm or less
The ratio (the ratio indicated by D in Table 2) exceeds 0.22 in terms of mass ratio
In Examples 5-7, 12-14, and 17-18,
The number of cracks is 0.1 / cm ^TwoLess and better
Good. In addition to the blast furnace slag fine powder,
In the examples in which the appropriate amount of
Has been reduced. Examples in which various additives were added
As a result, improvement in strength and reduction of cracks were achieved. Further
The solidified body according to the example obtained in the present invention and a comparative example
Of bending strength of solidified Portland cement and
Subbase determined by JIS A 1215 plate loading test
Table 5 shows the bearing force coefficient (K30). In addition, these results
The design of the thickness for road pavement with a service life of 20 years
The results are shown in Table 5. LA traffic and D traffic in the table are:
Shows the traffic volume of large vehicles, D traffic is 3000 vehicles / way
More than heading / day and less than LA traffic. The present invention
The solidified body obtained by
It is possible to design as a printing plate.

The solid obtained by the present invention is
mm or less, and Portland cement concrete crushed to 10 mm or less, add the same volume of water, immerse for 24 hours, filter the solids, and adjust the pH of the water.
Table 6 shows the results of the measurement. 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 Portland cement and was more preferable.

Further, among the solidified bodies of the present invention, Examples 1, 8, 18 and Comparative Example shown in Table 1 were cast outdoors and cured in a 5 m × 5 m area with a thickness of 30 cm. Table 7 shows the results of the investigation of the number of cracks on the body surface. The performance of the road pavement slab obtained by the present invention was the same as that of the concrete pavement slab.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4]

[0039]

[Table 5]

[0040]

[Table 6]

[0041]

[Table 7]

[0042]

According to the present technology, a cured product having high strength and almost no cracks in the surface layer can be obtained, and can be used as a road paving slab. 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 Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // (C04B 28/22 C04B 22:06 Z 22:06 22:14 A 22:14 22:12 22: 12 24:22 A 24:22 24:26) E 24:26) B09B 3/00 ZAB (72) Inventor Fumio Kogiku 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Pref. 1) Inventor Hisahiro Matsunaga 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture, Kawasaki Steel Engineering Co., Ltd. Terms (reference) 2D051 AF05 AF09 DA11 4D004 AA37 AA43 BA02 CA15 CA45 CC13 DA03 DA10 DA20 4G012 PB09 PB10 PB25 PB31

Claims (6)

[Claims] 1. A road pavement slab formed by kneading a mixture mainly composed of a granular steelmaking slag and a SiO ₂ -containing substance together with water, wherein the pH of the road pavement after contact with the pavement plate is 10%. A road pavement plate made of steelmaking slag, characterized by the following. 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 road paving slab made from steelmaking slag 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 mass ratio of the fly ash content to the total of the blast furnace slag fine powder content and the fly ash content is 30% by mass and the mass ratio is 0.1 to 0.75. Road pavement plate made of steelmaking slag. 4. The content of the hot metal pretreatment slag having a particle size of 1.18 mm or less with respect to the total of the content of the blast furnace slag fine powder, the content of fly ash and the content of the hot metal pretreatment slag having a particle size of 1.18 mm or less. The road paving slab made of steelmaking slag according to claim 2 or 3, wherein the mass ratio is more than 0.2. 5. The blast furnace slag fine mixture further comprises one or more selected from the group consisting of alkali metal and / or alkaline earth metal oxides, hydroxides, sulfates and chlorides. The road pavement using the steelmaking slag as a raw material 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 a total of a powder content and a fly ash content. Edition. 6. The mixture further comprises a naphthalene sulfonic acid and / or a polycarboxylic acid with respect to the total of the content of the blast furnace slag fine powder, the content of fly ash, and the content of hot metal pretreatment slag having a particle size of 0.1 mm or less. 0.
A road paving slab made from steelmaking slag according to any one of claims 2 to 5, which is a mixture containing 1 to 2.0% by mass.