JP2013006743A - Steel-making slag concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve flowability during manufacture and reduce drying shrinkage as well, in steel-making slag concrete using steel slag.SOLUTION: In steel-making slag concrete obtained by solidifying by hydration reaction of a mixture of materials including a binder containing blast furnace slag fine powder as an essential component, an aggregate containing steel-making slag as an essential component, and water, at least the blast furnace slag fine powder and steel-making slag fine powder having a maximum particle size of ≤400 μm are used as the binder, and the content of the steel-making slag fine powder is confined to 10-50 mass% relative to the total content of the blast furnace slag fine powder and the steel-making slag fine powder.

Description

  TECHNICAL FIELD The present invention relates to a steel slag hydrated solid body obtained by using steelmaking slag, blast furnace slag fine powder and water as essential materials, kneading them and solidifying them by a hydration reaction.

  In recent years, movements to effectively use materials produced as a by-product from various industrial facilities have become active due to the growing trend of protecting natural resources and utilizing recycled materials. Such materials include steel slag produced as a by-product in the steel process, but since this steel slag is generated in large quantities, efforts have been made since long ago for use as aggregates, roadbed materials, cement raw materials, etc. (for example, JIS R5211: Blast furnace cement, JIS A5011: Slag aggregate, etc.).

  However, steelmaking slag produced as a by-product in the steelmaking process in the steelmaking process contains free (free) CaO and MgO, and these oxides have a property of expanding by reacting with water. Therefore, the application of steelmaking slag to hardened bodies such as concrete has been considered difficult due to concerns about expansion cracks, and has become a barrier that promotes the use of recycled materials.

  Under such circumstances, in order to promote the utilization of recycled materials for steelmaking slag, for example, in Patent Documents 1 to 4, stability evaluation methods and quality for classifying steelmaking slag that does not cause expansion cracking in the cured body Standards are disclosed. In addition, blast furnace slag and cement are used as hardeners, and steel slag is used as aggregate, and steel slag hydrated solidified body (hereinafter simply referred to as “hydrated solidified body”) that can be prepared and handled in the same manner as concrete. The technical manual shown in the following non-patent document 1 has been disclosed.

  In such a hydrated solidified body using steelmaking slag, steelmaking slag with a particle size of 5 mm or less is used with a special function to the hydrated solidified body in order to reduce workability during freshness. It has only been used for As a method of using such a steelmaking slag having a particle size of 5 mm or less, for example, in Patent Document 5, in order to obtain the necessary strength expression as a slag hardened body while avoiding the influence of expansion of the steelmaking slag, A technique for mixing a predetermined amount of hot metal pretreatment slag of 1.18 mm or less is disclosed.

The technique described in Patent Document 5 was devised to solve the problem that steelmaking slag expands in a hardened body and causes the hardened body to expand and collapse (expansion cracking). The reason for this is that the concentration of free MgO (hereinafter referred to as “f-MgO”) in the steelmaking slag is used, and the hot metal pretreatment slag, which is a steelmaking slag not containing f-MgO, is used. However, simply using the hot metal pretreatment slag does not exhibit the same strength as concrete, so the technique of Patent Document 5 can take various means including mixing of granular steelmaking slag, which is usually difficult to use. It is said that sufficient strength can be ensured while avoiding the problem of expansion cracking of steelmaking slag. That is, in Patent Document 5, the component to be mixed with water is (1) the content of hot metal pretreatment slag having a particle size of 1.18 mm or less is 15 to 55 mass%.
(2) The content of fine blast furnace slag powder is 5 to 40 mass%.
(Claim 1).

Furthermore, the following method has also been proposed.
(3) Method of using fly ash as a pozzolanic substance (Claims 2 and 3)
(4) Method of adding alkali metal (Claim 4)
(5) A method of adding a naphthalenesulfonic acid-based admixture (claim 5)

JP 2004-301686A JP 2004-301694 A JP 2004-301747 A Japanese Patent Laid-Open No. 2004-301531 JP 2001-270746 A

Coastal Technology Research Center, “Steel Slag Hydrated Solid Technology Manual-Effective Utilization Technology of Steelmaking Slag (Revised Version), February 2008

  The purpose of the technique of Patent Document 5 is to obtain a hydrated and cured body that can sufficiently ensure strength development while avoiding the problem of expansion cracking of steel slag. Here, in Patent Document 5, the purpose of using the steelmaking slag having a particle size of 1.18 mm or less is only to ensure the strength expression of the cured body. As a supplement to the strength expression effect, a pozzolanic substance, an alkali metal, Addition of agent is positioned.

  By the way, steel slag has a bad surface shape due to the effects of rapid cooling and degassing in the manufacturing process and has a large water absorption rate. Therefore, when used in a hydrated solidified body, the amount of unit water for obtaining a predetermined fluidity increases. There was a problem of doing. The strength controlling factor in the hydrated solidified body is thought to be the mass ratio between the binder and water, as in concrete, and as the unit water volume increases, the amount of binder increases, leading to an increase in cost. The In order to suppress the amount of the binder, it is necessary to use an appropriate surfactant, but there is a problem that a high-performance surfactant (water reducing agent) having a greater effect is expensive. In order to avoid this problem, the unit water content was reduced to produce a hydrated solid product, which caused a problem that the workability at the time of freshness was remarkably reduced due to a decrease in fluidity, and it was impossible to perform the construction with a predetermined quality. .

  In addition, the hydrated solidified product using steelmaking slag is said to have a large volumetric shrinkage (drying shrinkage) during drying, and cracking due to drying shrinkage may occur. It is said to be inferior in terms of sex.

  However, in the hydrated solidified body using steelmaking slag, the technology to improve the fluidity during production and the technology to reduce the amount of drying shrinkage have not been proposed so far, and in order to promote the utilization of recycled materials, A means for solving the above-described problems has been desired.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to improve the fluidity at the time of production and to reduce the amount of drying shrinkage in a steel slag hydrated solid body using steel slag. It is to reduce.

  As a result of repeated earnest studies to solve the above problems, the present inventors further finely pulverized a steelmaking slag having a small particle size, which has been conventionally difficult to handle, and blended it in a predetermined amount to form a powder. It has been found that it is possible to improve fluidity during production and to reduce the amount of drying shrinkage, and based on this finding, the present invention has been completed.

  That is, according to the present invention, it is obtained by solidifying a mixture of a material containing a binder containing blast furnace slag fine powder as an essential component, an aggregate containing steelmaking slag as an essential component, and water by a hydration reaction. In the steel slag hydrate solidified body, at least the blast furnace slag fine powder and the steelmaking slag fine powder having a maximum particle diameter of 400 μm or less are used as the binder, and the content of the steelmaking slag fine powder is the blast furnace slag fine powder. And the steel slag hydrated solid body which is 10 mass% or more and 50 mass% or less with respect to the sum total of content of the said steelmaking slag fine powder is provided.

  Here, in the steel slag hydrated solidified body, the steelmaking slag fine powder is at least one selected from the group consisting of converter slag, secondary refining slag, hot metal pretreatment slag, dephosphorization slag and desulfurization slag. It may be a fine powder of steelmaking slag.

  According to the present invention, in steel slag hydrated solidified body using steelmaking slag, by replacing a part of the blast furnace slag fine powder used as a binder with steelmaking slag fine powder having a maximum particle size of 400 μm or less, It is possible to improve the fluidity of the resin and reduce the amount of drying shrinkage.

It is a graph which shows the particle size distribution of the converter slag used as the steelmaking slag fine powder of a present Example. It is a graph which shows the particle size distribution of the secondary refining slag used as steelmaking slag fine powder of a present Example. It is a graph which shows the particle size distribution of the hot metal pretreatment slag used as steelmaking slag fine powder of a present Example. It is a graph which shows the particle size distribution of the dephosphorization slag used as the steelmaking slag fine powder of a present Example. It is a graph which shows the particle size distribution of the dephosphorization and desulfurization slag used as the steelmaking slag fine powder of a present Example. It is a graph which shows an example of the relationship between the maximum particle size of steelmaking slag fine powder in a mortar test, and intensity. It is a graph which shows an example of the relationship between the 50% passage particle size and intensity | strength of the steelmaking slag fine powder in a mortar test. It is a graph which shows an example of the relationship between the fineness of steelmaking slag fine powder in a mortar test, and intensity. It is a graph which shows an example of the influence of the intensity | strength of the kind of aggregate in a mortar test. It is a graph which shows an example of the relationship between the addition amount of the steelmaking slag fine powder in a mortar test, and the intensity | strength of the 3rd day of age. It is a graph which shows an example of the relationship between the addition amount of the steelmaking slag fine powder in a mortar test, and the intensity | strength of 28th day of age. It is a graph which shows an example of the influence on the amount of drying shrinkage of the addition (43 mass%) of the steelmaking slag fine powder in a mortar test. It is a graph which shows an example of the influence on the amount of drying shrinkage of addition of steelmaking slag fine powder (99 mass%) in a mortar test. It is a graph which shows an example of the relationship between the addition amount and the slump value of the steelmaking slag fine powder in a solidified body test. It is a photograph which shows an example of the difference in the slump by the presence or absence of addition of the steelmaking slag fine powder in a solidified body test. It is a graph which shows an example of the relationship between the age (day) and intensity | strength at the time of adding 43 mass% of steelmaking slag fine powder in a solidified body test. It is a graph which shows an example of the relationship between the age (day) and intensity | strength at the time of adding 100 mass% (the blast furnace slag fine powder is not added) steelmaking slag fine powder in a solidification body test. It is a graph which shows an example of the relationship between the addition amount of the steel-making slag fine powder in a solidification body test, and the intensity | strength of the age 7th day. It is a graph which shows an example of the relationship between the addition amount of the steel-making slag fine powder in a solidification body test, and the intensity | strength of 28th day of age.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

[Configuration of steel slag hydrated solidified body]
First, the structure of the steel slag hydrated solid body according to a preferred embodiment of the present invention will be described in detail. The steel slag hydrated solid body according to the present embodiment can improve fluidity (workability during freshness) during production and can reduce the amount of drying shrinkage.

(Overview of hydrated solidified product)
In general, a steel slag hydrated solidified body is obtained by mixing steel slag, blast furnace slag fine powder, and water, which are produced as by-products in the iron making process, as essential components, and these materials are kneaded and solidified by a hydration reaction. Moreover, the steel slag hydrated solidified body may contain, as necessary, alkali-stimulated material, fly ash, granulated blast furnace slag equivalent to fine aggregate, and the like. Iron and steel slag hydrated solid bodies are roughly classified into two types, type I and type II, depending on the type and amount of the alkali stimulating material, and each type is classified into two of A and B depending on the amount of steelmaking slag used as an aggregate. Divided into types.

  The hydrated solidified body according to the present embodiment is a steel slag hydrated solidified body as described above, and a predetermined amount of the blast furnace slag fine powder used as a binder is a steelmaking slag fine powder having a maximum particle size of 400 μm or less. Is replaced. Hereinafter, each component contained in the hydrated solid body according to the present embodiment will be described in detail.

(Steel slag)
Steelmaking slag is an inorganic substance mainly composed of CaO, SiO ₂ , Al ₂ O _3, etc., produced in the steelmaking process for producing steel by refining hot metal, scrap, etc., and as an aggregate in a hydrated solidified body The material used. Steelmaking slag also acts as an alkali stimulant that releases Ca ²⁺ and OH ⁻ in the presence of moisture and accelerates the hydration and hardening of blast furnace slag fine powder. Furthermore, it acts as a Ca supply source for the pozzolanic reaction by fly ash. The amount of steelmaking slag in the hydrated solidified body is determined in consideration of the unit volume mass and workability of the hydrated solidified body, but is usually a content of 60% by mass or more.

  Here, as steelmaking slag used for the hydrated solid body according to the present embodiment, as defined in Non-Patent Document 1, the powdering rate is 2.5% or less, and the MgO content is 8.5% or less. It is preferable to use a steelmaking slag that satisfies the quality of a maximum particle size of 25 mm or less. The pulverization rate is a ratio indicating the amount of pulverized slag generated in steelmaking slag by water immersion treatment for 10 days at 80 ° C., and is calculated using the method described in Non-Patent Document 1. The MgO content is an index indicating the degree of free-MgO (free magnesia) contained in the steelmaking slag, and the quantitative method defined in JIS M8205 (“Iron Ore—Fluorescent X-ray Analysis Method”) is used. Then, it is calculated by the method described in Non-Patent Document 1. The maximum particle size is a value measured by a method defined in JIS A1102 (“Aggregate Screening Test Method”).

  In addition, the steelmaking slag used as an aggregate in the hydrated solidified body is one that has been subjected to an aging treatment, unlike the steelmaking slag fine powder described later, in order to prevent expansion of the steelmaking slag in the hydrated solidified body. Use. Aging is a treatment to expose unreacted substances such as free-CaO (free lime) and free-MgO in steelmaking slag for a certain period of time. There is steam aging that reacts with high temperature steam. In general, by performing natural aging for 6 months or more, or steam aging for about 3 to 7 days, it is possible to satisfy the standard of the powdering rate applicable to the hydrated solidified body.

(Blast furnace slag fine powder)
The ground granulated blast furnace slag is obtained by quenching a molten blast furnace slag produced simultaneously with pig iron in a blast furnace with water and then drying and pulverizing it, or adding gypsum to this. Blast furnace slag fine powder has weak hydraulic properties in the presence of water, and exhibits strong hydraulic properties due to stimulation of alkaline substances such as calcium hydroxide. Thus, the blast furnace slag fine powder is used as a binder in the hydrated solidified body because the hydration reaction is promoted in the presence of the alkali stimulating material and exhibits a hardening phenomenon.

  In addition, blast furnace slag fine powder may have different hydration characteristics and strength development characteristics depending on its fineness and components, etc. As the blast furnace slag fine powder used for the body, a blast furnace slag fine powder conforming to JIS A6206 (“concrete blast furnace slag fine powder”) is used. In addition, what is necessary is just to determine the content of the blast furnace slag fine powder by a test so that the required performance and appropriate workability of the hydrated solidified body can be obtained.

(Steel slag fine powder)
In the hydrated solid body according to the present embodiment, steelmaking slag fine powder is used as a binder instead of part of the blast furnace slag fine powder. The steelmaking slag fine powder in the present embodiment is a steelmaking slag powder having a maximum particle size of 400 μm or less, and improves the fluidity in the production process of the hydrated solidified body and reduces the amount of drying shrinkage of the hydrated solidified body. It is a material used for the purpose.

<Particle size of steelmaking slag fine powder>
This steelmaking slag fine powder has a maximum particle size of 400 μm or less because when this steelmaking slag fine powder is used as a binder, the amount of drying shrinkage of the hydrated solidified body can be reduced. The maximum particle size (particle size distribution) of the steelmaking slag fine powder can be measured using a laser particle size distribution measuring machine or the like.

<Content of fine steelmaking slag powder>
Moreover, content of the steelmaking slag fine powder used for the hydrated solid body according to the present embodiment is 10% by mass or more and 50% by mass or less with respect to the total content of the blast furnace slag fine powder and the steelmaking slag fine powder. By setting the content of the steelmaking slag fine powder to 10% by mass or more, the fluidity in the production process of the hydrated solidified body can be improved, and the unit water amount can be reduced. Moreover, the amount of drying shrinkage of the hydrated solidified body can be reduced by setting the content of the steelmaking slag fine powder to 10% by mass or more. On the other hand, when the content of the steelmaking slag fine powder exceeds 50% by mass, the strength reduction of the hydrated solidified product tends to be remarkable. From the viewpoint of securing the strength, the content of the steelmaking slag fine powder is 50% by mass. % Or less.

<Physical properties of fine steelmaking slag powder>
The steelmaking slag fine powder used as a binder in the present embodiment is different from the steelmaking slag used as an aggregate described above, and it is necessary to use a powdering rate of 2.5% or less and a MgO content of 8.5% or less. There is no.

<With or without aging treatment>
In addition, the steelmaking slag fine powder used as a binder in the present embodiment is different from the steelmaking slag used as an aggregate described above, because the particle size is small, even if expanded, the influence on cracking of the hydrated solidified body is not Since there is almost no, the steelmaking slag before an aging process may be grind | pulverized and used. In particular, from the viewpoint of reducing the amount of drying shrinkage of the hydrated solid product, it is preferable to use one that has not been subjected to an aging treatment.

<Types of steelmaking slag fine powder>
In addition, the type of the steelmaking slag fine powder is not particularly limited as long as it is within the above-described maximum particle size and content range. Examples of the steelmaking slag fine powder according to this embodiment include converter slag, A fine powder of at least one steelmaking slag selected from the group consisting of secondary refining slag, hot metal pretreatment slag, dephosphorization slag and desulfurization slag can be used.

(water)
Water is necessary for solidifying the hydrated solid body and is a material necessary for ensuring sufficient workability in construction. In addition, the amount of water added may be determined by tests so that the required performance and appropriate workability of the hydrated solidified body can be obtained, but in order to sufficiently ensure the performance such as strength and durability, As with concrete, it is important to use as little as possible. In addition, since the water used for the hydrated solid body should not contain harmful impurities, tap water, JSCE-B 101 (“Quality Standard for Concrete Mixing Water”) or JIS A5308 Annex 9 ("Water used for mixing ready-mixed concrete") is used.

(Alkali stimulant)
The alkali stimulating material is an alkaline substance added to accelerate the hydration reaction of the blast furnace slag fine powder. For example, Ca-based alkali stimulating materials such as slaked lime and various cements are used as necessary. Specifically, as an alkali stimulant used for the steel slag hydrated solidified type I, the quality of Ca (OH) ₂ or CaO-contained has been confirmed, and the performance of the steel slag hydrated solidified product is Use a product that has been confirmed to be satisfactory by testing. In addition, as the alkali stimulant used for the steel slag hydrated solidified type II, those suitable for JIS R5210 (“Portland cement”) and JIS R5211 (“blast furnace cement”) are used.

  Since steelmaking slag also has an alkali stimulating action of blast furnace slag fine powder, the hydrated solidified body of steel slag solidifies (hardens) only with steelmaking slag, fine blast furnace slag powder and water. When an alkali stimulating material is added, it can be solidified more quickly. Further, the alkali stimulating material has an action of promoting the pozzolanic reaction of fly ash.

(Fly ash)
Fly ash is a material that is used as necessary as an additional binder for steel slag hydrated solidified bodies. Since fly ash causes a pozzolanic reaction with Ca (OH) ₂ and hardens, it acts as a binder for the hydrated solidified body. When such fly ash is used, there are effects of improving strength at long-term ages, reducing the amount of alkali components eluted from the hydrated solid body when immersed in water, and improving workability in a fresh state. Since fly ash affects hydration characteristics, strength development characteristics, workability, etc. depending on the fineness and content of the components, JIS A6201 (“Concrete fly ash” is used to stably obtain the quality of the hydrated solidified product. )) Or equivalent products are used.

  In the hydrated solid body according to the present embodiment, fly ash may be used as a material equivalent to fine aggregate, not as a binder.

(Blast furnace granulated slag)
Granulated blast furnace slag is a blast furnace slag in a molten state produced in the ironmaking process for producing pig iron, rapidly cooled with water and finely divided, and has weak hydraulic properties. Blast furnace granulated slag is used as necessary for a hydrated solidified body of steel slag as a material equivalent to fine aggregate. However, blast furnace granulated slag affects hydration characteristics, strength development characteristics, workability, etc. depending on its particle size and shape, etc. In order to stably obtain the quality of the hydrated solidified body, JIS A6206 (“Concrete Blast furnace slag fine powder ") or a material suitable for JIS A5011-1 (" Concrete slag aggregate-Part 1: Blast furnace slag aggregate ") is used.

(Other materials)
In addition, the hydrated solid body according to the present embodiment may include materials such as an admixture, a fine aggregate, and a coarse aggregate. The admixture is a material used for adjusting the unit water amount and the air amount used for the hydrated solid body, and AE agent for concrete, AE water reducing agent, high performance AE water reducing agent, and the like are used. In addition, aggregates other than steelmaking slag used for hydrated solidified bodies are granulated blast furnace granulated slag and natural aggregate, etc., but aggregates other than blast furnace granulated slag are "Creation [Construction]" is used.

  In addition, as essential components of the hydrated solid body according to the present embodiment, steelmaking slag, blast furnace slag fine powder, steelmaking slag fine powder and water, the present inventor has other components (for example, blast furnace granulation). Even if slag, fly ash, alkali stimulating material, etc.) are included, it has been confirmed that the same effect can be obtained with respect to the improvement effect of the fluidity and the reduction hardening of the drying shrinkage amount in this embodiment.

[Method for producing hydrated and solidified steel slag]
As mentioned above, although the structure of the steel slag hydrated solid body which concerns on this embodiment was demonstrated in detail, it continues and the manufacturing method of the steel slag hydrated solid body which concerns on this this embodiment is demonstrated.

(Manufacturing method flow)
In the method for producing a hydrated solid body according to the present embodiment, first, blast furnace slag fine powder and steelmaking slag fine powder having a maximum particle size of 400 μm are added to steelmaking slag, and are kneaded and solidified with water. At the time of kneading, as described above, the addition amount of the steelmaking slag fine powder is 10% by mass or more and 50% by mass or less with respect to the total addition amount of the blast furnace slag fine powder and the addition amount of the steelmaking slag fine powder. If necessary, blast furnace granulated slag, fly ash, alkali stimulating material and the like are added and blended. Thereafter, a steel slag hydrated solid body is manufactured through steps such as implantation into a mold and curing.

(Hardening mechanism of hydrated solid body)
Here, the mechanism by which the hydrated solid material solidifies (hardens) during kneading is as follows. That is, by kneading the various materials described above, calcium hydroxide, which is one of the components contained in steelmaking slag, dissolves in water, and the blast furnace slag fine powder is alkali-stimulated. Thereby, elements such as Si, Al, and Ca contained in the amorphous phase of the blast furnace slag fine powder are hydrated and cured. Further, when fly ash is added as a material of the hydrated solidified body, curing of the material is also promoted by a pozzolanic reaction in which fly ash reacts with Ca. Moreover, the said reaction will be further accelerated | stimulated by the cement represented by slaked lime and Portland cement being added as an alkali stimulant.

  Hereinafter, based on an Example, the steel slag hydrated solid body which concerns on this invention is demonstrated more concretely.

As the steelmaking slag fine powder used in Examples and Comparative Examples of the present invention, those having the physical properties shown in Table 1 below were used. The maximum particle size is 90 to 400 μm, the 50% passing particle size is 6.23 to 18.39 μm, and the fineness (specific surface area by Blaine method) is 550 to 4340 cm ² / g. For reference, the particle size distribution of each steelmaking slag fine powder is shown in FIGS.

  Table 2 below shows the test conditions of the tests performed on the examples and comparative examples. The test is to investigate the compressive strength and drying shrinkage rate when using steelmaking slag fine powder in the mortar test, and the compressive strength when using steelmaking slag fine powder in the solidified body test including coarse aggregate And a fluidity survey. In the following tests, for example, “3-day compressive strength” or “3-day strength” indicates the compressive strength at the age of 3 days. The strength index is an indicator of the strength of steel slag hydrated solids at the age of 28 days. Generally, (BP + CH + 2NP + 0.35FA) / W (BP: ground granulated blast furnace slag, CH: slaked lime, NP: ordinary Portland cement In this example, CH, NP, and FA are not used, but SP (steel-making slag fine powder) is used. Therefore, the strength index is represented by (BP + SP) / W. The compressive strength is measured according to JIS A 1108 “Concrete compressive strength test method”, and the drying shrinkage is measured according to JIS A 1192 “Mortar and concrete length change test method”. The slump value was measured according to the “dial gauge method”, and the measurement of the slump value was performed according to JIS A 1101 “Concrete slump test method”.

(Mortar test)
(1) Test conditions The blending of the materials in Examples and Comparative Examples was carried out according to the blending shown in Table 3 below. The concept of blending setting is as follows.

  First, in order to confirm the effectiveness of adding steelmaking slag fine powder to a mixture of water, blast furnace slag fine powder and steelmaking slag, which is a combination of basic materials of the hydrated solidified body of the present invention, steelmaking slag fine powder The mixing | blending case which changes the kind and addition amount of No.2 was set (refer No.2-4, 6-7, 9-10, 12-13, 15-16 of Table 3).

  Next, since the prior art is a hydrated solidified body that does not use steelmaking slag fine powder, in order to confirm the difference between this hydrated solidified body and the hydrated solidified body of the present invention, water, blast furnace slag fine powder, A blending case using steelmaking slag was set as a comparative example (see No. 1 in Table 3).

  Furthermore, in order to prove the effect of the steelmaking slag used as an aggregate as a constituent material, a mixed case using natural sand as an aggregate was examined as a comparative example (Nos. 5, 8, 11, 14, 17 in Table 3). See).

  In addition, “addition amount of steelmaking slag fine powder” in Table 3 means the blending ratio (mass%) of the steelmaking slag fine powder to the total mass of the blast furnace slag fine powder and the steelmaking slag fine powder.

(2) Relationship between the particle size and strength of the steelmaking slag fine powder First, the results of examining the appropriate range of the particle size of the steelmaking slag fine powder will be described. In addition, in this examination, the addition amount of steelmaking slag fine powder was 43 mass% with respect to the total addition amount of blast furnace slag fine powder and steelmaking slag fine powder.

  In FIG. 6, the result of having examined about the relationship between the maximum particle size of steelmaking slag fine powder and compressive strength is shown. From this result, it was found that there was almost no change in strength when the maximum particle size of the steelmaking slag fine powder of the present invention was 400 μm or less.

  For reference, FIG. 7 shows the relationship between the 50% passing particle size of the steelmaking slag fine powder and the compressive strength, and FIG. 8 shows the relationship between the fineness of the steelmaking slag fine powder and the compressive strength. However, the intensity change was found to be small. This result shows that if the particle size of the steelmaking slag fine powder is within a certain range, the components and activity of the steelmaking slag do not affect the strength.

(3) Combination of used aggregate Next, the result of having examined the suitable combination of the material of steel slag hydrated solidified body is demonstrated. In addition, in this examination, the addition amount of steelmaking slag fine powder was 43 mass% with respect to the total addition amount of blast furnace slag fine powder and steelmaking slag fine powder.

  FIG. 9 shows the relationship between the type of aggregate used and the compressive strength. From this result, it was found that when the aggregate is made of natural sand, the strength expression becomes extremely worse. In order to exert the potential hydraulic properties of the blast furnace slag fine powder, it is necessary to use steelmaking slag as an aggregate, that is, a combination of materials in the hydrated solid body according to the present invention.

(4) Steelmaking slag fine powder addition amount and strength Next, the results of examining an appropriate range of the steelmaking slag fine powder addition amount will be described.

  10 and 11, the blending ratio (mass%) of the steelmaking slag fine powder with respect to the total mass of the blast furnace slag fine powder and the steelmaking slag fine powder (hereinafter referred to as “addition amount of the steelmaking slag fine powder” may be described. .) And the compressive strength. FIG. 10 shows the result of measuring the compressive strength at the age of 3 days, and FIG. 11 shows the result of measuring the compressive strength at the age of 28 days. As shown in FIGS. 10 and 11, regardless of the age, when the added amount of the steelmaking slag fine powder exceeds 50% by mass, there is a tendency that the decrease in compressive strength becomes significant. Therefore, from the viewpoint of securing the strength of the hydrated solidified body, it is considered that the addition amount of the steelmaking slag fine powder should be 50% by mass or less with respect to the total addition amount of the blast furnace slag fine powder and the steelmaking slag fine powder. It is done.

(5) Reduction Effect of Drying Shrinkage by Addition of Steelmaking Slag Fine Powder Next, the results of examining the influence on the drying shrinkage by adding the steelmaking slag fine powder in the hydrated solidified body according to the present invention will be described.

  FIG. 12 and FIG. 13 show an example of the change over time in the amount of drying shrinkage when steelmaking slag fine powder is added. FIG. 12 shows an example in which the addition amount of the steelmaking slag fine powder is 43 mass%, and FIG. 13 is an example in which the addition amount of the steelmaking slag fine powder is 99 mass%. The hydrated solidified body is required to have a dry shrinkage amount as small as possible from the viewpoint of ensuring durability against cracks after hardening, but the addition of fine steelmaking slag powder significantly reduces the dry shrinkage amount. I found out. From the standpoint of suppressing the amount of drying shrinkage, it is presumed that the effect is greater when the amount of steelmaking slag fine powder added is increased. However, from the viewpoint of coexistence with the strength development of the hydrated solidified body, the addition amount of the steelmaking slag fine powder should be 50% by mass or less with respect to the total addition amount of the blast furnace slag fine powder and the steelmaking slag fine powder. Was found to be necessary.

(Solidified body test)
(1) Test conditions A test was conducted on a solidified body obtained by adding a coarse particle having a maximum particle size of more than 5 mm to steelmaking slag used as an aggregate. The blending of the materials in Examples and Comparative Examples was performed according to the blending shown in Table 4 below. The concept of blending setting is as follows.

  First, the steelmaking slag fine powder is mixed into a mixture of water, blast furnace slag fine powder, and steelmaking slag (both particle sizes of 5 mm or less, both exceeding 5 mm), which are a combination of basic materials of the hydrated solidified body of the present invention. In order to confirm the effect of adding, the mixing | blending case which changes the kind and addition amount of steelmaking slag fine powder was set (refer No. 2-11 of Table 4).

  Next, since the prior art is a hydrated solidified body that does not use steelmaking slag fine powder, in order to confirm the difference between this hydrated solidified body and the hydrated solidified body of the present invention, water, blast furnace slag fine powder, A blending case using steelmaking slag (both particle diameters of 5 mm or less and both exceeding 5 mm was used) was set as a comparative example (see No. 1 in Table 4).

  In addition, "addition amount of steelmaking slag fine powder" in Table 4 means the blending ratio (mass%) of the steelmaking slag fine powder to the total mass of the blast furnace slag fine powder and the steelmaking slag fine powder.

The “fine aggregate ratio” in Table 4 means the volume ratio of fine aggregate (aggregate of 5 mm or less) in the total aggregate volume. Here, in Table 4, No. 1 and No. Taking 2 as an example, a method for calculating the fine aggregate rate will be described. First, the surface dry density of the used steelmaking slag (30-5) is 3.06 g / cm ³ , and the surface dry density of the steelmaking slag (5-0) is 2.45 g / cm ³ . Although this is not described in Table 4, it is an actual measurement value obtained by measurement performed in advance.

No. 1, the unit amount of steelmaking slag (30-5) is 1000 kg / m ³ , and the unit amount of steelmaking slag (5-0) is 686 kg / m ³ . In terms of volume, steelmaking slag (30-5) = 1000 / 3.06 = 327 liter / m ³ , and steelmaking slag (5-0) = 686 / 2.45 = 280 liter / m ³ . Therefore, the fine aggregate ratio = 280 / (327 + 280) × 100 = 46.1%.

No. In 2, the unit amount of steel slag (30-5) is a 1013kg / ^{m 3,} the unit amount of steel slag (5-0) is 693kg / ^{m 3.} In terms of volume, steelmaking slag (30-5) = 1013 / 3.06 = 331 liter / m ³ , and steelmaking slag (5-0) = 693 / 2.45 = 283 liter / m ³ . Therefore, the fine aggregate ratio = 283 / (331 + 283) × 100 = 46.1%.

(2) Effect of improving fluidity by adding steelmaking slag fine powder First, the results of examining the effect of improving fluidity by adding steelmaking slag fine powder will be described.

  FIG. 14 shows an example of the relationship between the added amount of steelmaking slag fine powder and the slump value. FIG. 15 shows an example of the difference in slump depending on whether or not steelmaking slag fine powder is added.

As shown in FIGS. 14 and 15, it can be seen that the addition of the steelmaking slag fine powder increases the fluidity of the hydrated solidified body when fresh. It can also be seen that the effect of increasing the fluidity becomes more significant as the amount of steelmaking slag fine powder added increases. The following actions can be expected due to the improvement effect of the fluidity.
1) The same slump, that is, the unit water amount necessary for obtaining fluidity can be reduced (specifically, a reduction in unit water amount of about 10 to 15% can be expected). Since the strength of the hydrated solid body is determined by the ratio between the unit water amount and the fine powder amount of the binder, the reduction of the unit water amount leads to the reduction of the high-powder fine powder amount, and the cost can be reduced.
2) It is possible to reduce the amount of admixture (a surfactant such as naphthalene sulfonic acid type and polycarboxylic acid type) which has been conventionally added to ensure fluidity, and the cost can be reduced.
3) By reducing the amount of unit water, the amount of drying shrinkage of the hydrated solid body is reduced, and by suppressing the occurrence of drying shrinkage cracks, the durability of the hydrated solid body is improved.

(3) Effect on strength characteristics due to addition of steelmaking slag fine powder Next, the results of studies on the influence on strength characteristics due to the addition of steelmaking slag fine powder will be described.

  FIG. 16 shows the relationship between the age (day) and the strength when 43 mass% of steelmaking slag fine powder is added. Moreover, in FIG. 17, the relationship between the age (day) and intensity | strength at the time of adding 100 mass% (no blast furnace slag fine powder addition) steelmaking slag fine powder was shown.

  As shown in FIG. 16, when the addition amount of steelmaking slag fine powder is 43 mass%, compared with the case where steelmaking slag fine powder is not added, the intensity | strength comparable is shown. On the other hand, as shown in FIG. 17, when the addition amount of the steelmaking slag fine powder is 100% by mass, the strength is remarkably reduced as compared with the case where the steelmaking slag fine powder is not added. Recognize. Therefore, excessive addition of steelmaking slag fine powder is not preferable.

  Then, next, the addition amount of steelmaking slag fine powder was examined. 18 and 19 show the relationship between the amount of steelmaking slag fine powder added and the compressive strength. FIG. 18 shows the result of measuring the compressive strength at the age of 7 days, and FIG. 19 shows the result of measuring the compressive strength at the age of 28 days.

  As shown in FIGS. 18 and 19, an increase in the amount of steelmaking slag fine powder added (replacement ratio of steelmaking slag fine powder to blast furnace slag fine powder) causes a decrease in strength of the solidified body, regardless of the age. Specifically, when the added amount of the steelmaking slag fine powder exceeds 50% by mass, there is a tendency that the decrease in compressive strength becomes significant. Therefore, from the viewpoint of securing the strength of the hydrated solidified body, it is considered that the addition amount of the steelmaking slag fine powder should be 50% by mass or less with respect to the total addition amount of the blast furnace slag fine powder and the steelmaking slag fine powder. It is done.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

Claims (2)

In a steel slag hydrated solidified body obtained by solidifying a mixture of a material containing a blast furnace slag fine powder as an essential component, an aggregate containing steelmaking slag as an essential component, and water by a hydration reaction,
As the binder, at least, a blast furnace slag fine powder and a steelmaking slag fine powder having a maximum particle size of 400 μm or less,
The steel slag fine powder content is 10% by mass or more and 50% by mass or less based on the total content of the blast furnace slag fine powder and the steelmaking slag fine powder. body. The steelmaking slag fine powder is a fine powder of at least one steelmaking slag selected from the group consisting of converter slag, secondary refining slag, hot metal pretreatment slag, dephosphorization slag and desulfurization slag. The steel slag hydrated solidified body according to claim 1.