JP2014065626A - Cement admixture and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement admixture and a cement composition capable of exhibiting excellent crack self-healing properties even in a small amount with no possibility of reducing fluidity.SOLUTION: There is provided a cement admixture which contains blast furnace slug particles containing 0.5 mass% or more of iron and a stimulating material containing at least one selected from the group consisting of calcium hydroxide, calcium oxide, calcium sulfate, aluminum sulfate and lithium sulfate.

Description

  The present invention relates to a cement admixture and a cement composition containing the cement admixture.

Cement hardened bodies such as mortar and concrete are hardened by the hydration reaction of cement contained in the cement composition, but after hardening, stress acts and changes in temperature and humidity occur. Cracks may occur in the cured body.
The hardened cement body having cracks has a problem that it causes water leakage and the like in addition to a decrease in strength and deterioration in appearance.

  Therefore, in recent years, hardened cement bodies having a property of naturally closing cracks in the presence of moisture even when cracks occur after curing, so-called self-healing properties, have been studied. In order to obtain such a hardened cement body having self-healing properties, various cement admixtures are blended into the cement composition.

For example, Patent Documents 1 to 3 describe cement compositions in which an expansion material having an action of reacting with calcium hydroxide or the like in cement to generate insoluble crystals is blended.
Patent Document 4 describes a cement composition in which an aluminosilicate having swelling property is further blended in addition to the expansion material.
Patent Document 5 describes a cement admixture granulated by kneading a component such as an expansion material component, a latent hydraulic material, calcium oxide, cement, and water.
Patent Documents 6 and 7 describe a bone for a hardened cement body, in which a waterproofing agent / water-stopping agent / deterioration inhibitor such as water-soluble silicic fluoride is mixed with cement and loaded on a carrier made of a porous body. The materials are listed.

  That is, Patent Documents 1 to 7 include a component that reacts with a component in a cement composition in the presence of water to generate crystals or the like, or a component that swells when cracks occur in the hardened cement body. It is described that by adding a cement admixture to a cement composition, the cement composition is provided with a crack self-healing property capable of closing the crack and self-healing.

Japanese Patent No. 3658568 JP 2005-239482 A JP 2007-332010 A JP 2009-190937 A JP 2011-57520 A JP 2003-95715 A Japanese Patent No. 4285675

However, the expandable materials and aluminosilicates described in Patent Documents 1 to 4 are materials having high water absorption, swelling properties, and high reaction activity with water. Therefore, when directly mixed with a cement composition, There is a risk of reducing the fluidity of fresh mortar.
In order to suppress such a decrease in fluidity, it is necessary to increase the amount of water-reducing agent or high-performance water-reducing agent. However, if the amount of water-reducing agent or high-performance water-reducing agent is increased, setting delay or There is a risk that strength will be reduced. In addition, there is a problem that costs for increasing water reducing agents, high performance water reducing agents, and the like are increased.

  Like the cement admixture described in Patent Document 5, by using a cement admixture that is granulated by kneading a component having crack self-healing properties with cement, a decrease in fluidity can be suppressed to some extent. However, in the case of a granulated product, since the above components are also present in the central part, the components in the central part may remain unreacted in the granulated product without reacting with water when cracking occurs. . Also in the aggregates described in Patent Documents 6 and 7, since the carrier is a porous body, the components present in the pores may remain unreacted with water. Therefore, the admixtures described in Patent Documents 5 to 7 need to be added to the cement composition in anticipation of the unreacted residual amount in order to obtain sufficient crack self-healing properties.

  In view of the above problems, an object of the present invention is to provide a cement admixture and a cement composition that are capable of exhibiting high crack self-healing properties even in a small amount without causing a decrease in fluidity.

  The cement admixture of the present invention contains a blast furnace slag particle containing 0.5% by mass or more of iron and at least one selected from the group consisting of calcium hydroxide, calcium oxide, calcium sulfate, aluminum sulfate, and lithium sulfate. Material.

The cement admixture of the present invention exhibits an excellent crack healing effect by including blast furnace slag particles containing 0.5% by mass or more of iron and the stimulant.
That is, the blast furnace slag particles have a latent hydraulic property that initiates a hydration reaction upon stimulation with a strong alkaline substance such as calcium hydroxide or a sulfate such as gypsum produced by a hydration reaction of cement. However, the blast furnace slag particles contain iron in the above range, so that each component in the cement composition, water, oxygen and the iron react with each other. Generates expansive precipitates such as iron oxide or iron hydroxide. In other words, the blast furnace slag particles containing the above amount of iron can crack the self-cracked slag particles because the blast furnace slag particles themselves can harden and form cracks in the hardened cement body, while the precipitates are formed in the cracked parts. The healing property is high, and therefore, sufficient cracking self-healing property can be obtained even with a small amount of use.
Moreover, when it mix | blends with a cement composition by including the said blast furnace slag particle | grains and the said stimulant, a fluid fall can be suppressed, without adding an additive.

In the present invention, the amount of iron in the blast furnace slag particles refers to the amount of iron measured by the following measuring method.
20 kg of absolutely dry blast furnace slag particles are coarsely pulverized using a pulverizer such as a horizontal brown pulverizer (disc mill), and specified in JIS Z8801-1 “Test Net Sieve Part 1: Metal Net Sieve”. The test sieve was passed through a sieve with a nominal aperture of 2.36 mm, and then subjected to magnetic separation for 10 minutes using a counter magnetic separator with a magnetic flux density of 2.7 Tesla (processing capacity: 120 kg per hour). Processing is performed to obtain a recovered material mainly composed of iron. After measuring the mass of the recovered material, the entire amount of the recovered material was pulverized using a disk-type vibration mill made of tungsten carbide, and JIS R 5204 “cement” using a wavelength dispersive X-ray fluorescence analyzer (WDXRF). The content of iron (FeO = divalent iron oxide equivalent) of the recovered material is measured by a powder briquette method in accordance with the “XRF analysis method”. From the mass of the recovered material and the content of iron (converted to FeO) in the recovered product, the mass% of iron (converted to FeO) in the blast furnace slag particles is calculated.

  In the present invention, the blast furnace slag particles may contain 4.0 mass% or less of the iron.

  When the blast furnace slag particles contain 4.0 mass% or less of the iron, sufficient cracking self-healing property can be obtained even with a small amount of use, and at the same time, a decrease in fluidity when blended with a cement composition can be suppressed. Moreover, it can suppress that rust generate | occur | produces more than necessary in a hardened cement body, and impairs an external appearance.

  In the present invention, the stimulant may be attached to the surface of the blast furnace slag particles.

  When the stimulant is attached to the surface of the blast furnace slag particles, when cracks occur in the hardened cement body, the stimulant is present on the surface of the blast furnace slag particles exposed in the cross section of the cracks. The stimulant easily reacts in the crack cross section, and the cracks are easily blocked. Therefore, a higher crack self-healing effect can be exhibited.

  The stimulating material may include cement.

  When the stimulating material includes cement, the stimulating material is easily attached to the surface of the blast furnace slag, and the stimulating material is more likely to react.

  In this invention, the said blast furnace slag particle | grains to which the said stimulant containing calcium hydroxide adhered to the surface, and the said blast furnace slag particle | grains to which the said stimulant containing calcium sulfate adhered to the surface may be included.

  By including the blast furnace slag particles with the stimulant containing calcium hydroxide attached to the surface and the blast furnace slag particles with the stimulant containing calcium sulfate attached to the surface, a higher crack self-healing effect can be obtained. Can be demonstrated.

In the present invention, the stimulus material, Al ₂ O ₃ and SO _3, the molar ratio of SO ₃ for Al ₂ O ₃ may be contained such that 0.01 to 27.3 or less.

By containing SO ₃ and Al ₂ O ₃ in the above molar ratio range, higher crack self-healing performance can be exhibited.

  Moreover, the cement composition of the present invention contains the cement admixture.

  According to the present invention, it is possible to provide a cement admixture and a cement composition capable of exhibiting high crack self-healing property even in a small amount without causing a possibility of lowering fluidity.

  Hereinafter, embodiments of the cement admixture and the cement composition of the present invention will be specifically described.

"Cement admixture"
First, the cement admixture of this embodiment will be described.
The cement admixture of the present embodiment includes blast furnace slag particles containing 0.5% by mass or more of iron and at least one selected from the group consisting of calcium hydroxide, calcium oxide, calcium sulfate, aluminum sulfate, and lithium sulfate. A cement admixture containing an irritant.

(Blast furnace slag particles)
The blast furnace slag particles may be any blast furnace slag generated from an iron making blast furnace, and examples thereof include blast furnace granulated slag, blast furnace slow-cooled slag, and the like.
The amount of blast furnace slag generated in Japan is an enormous amount of about 20 million tons per year, and an effective method for reducing the environmental burden has been demanded in recent years. Conventionally, blast furnace slow-cooled slag has been used as a raw material for cement and roadbed materials, and granulated blast furnace slag has been used as a mixed material for cement, but most of the blast furnace slag generated as a by-product has been effectively used. Absent.
By using such blast furnace slag as a raw material, the raw material cost of the cement admixture of the present embodiment is reduced.

《Blast Furnace Granulated Slag》
When smelting pig iron from iron ore, the blast furnace granulated slag was rapidly cooled and solidified by injecting high pressure water from the blast furnace in a high temperature molten state exceeding 1500 ° C., and then adjusted to a predetermined particle size. Is.
Granulated blast furnace slag contains a large amount of amorphous (glassy) calcium silicate, etc., and hydrates by stimulation with highly alkaline substances such as calcium hydroxide and Portland cement, and sulfates such as calcium sulfate. Has the resulting hydraulic potential.
In the hydration reaction of granulated blast furnace slag, calcium silicate-based hydrate and calcium aluminate-based hydrate are likely to be precipitated, which is preferable as the blast furnace slag particles of the present embodiment.

  As the granulated blast furnace slag, for example, blast furnace slag fine aggregate (particle size range = 5 mm or less) conforming to JIS A 5011-1, "Slag aggregate for concrete Part 1: Blast furnace slag aggregate", or Examples include pulverized and classified blast furnace slag fine aggregate. Among the blast furnace slag fine aggregates, 2.5 mm blast furnace slag fine aggregate (BFS2.5), 1.2 mm blast furnace slag fine aggregate (BFS1.2), 0.3-5 mm blast furnace slag having a relatively small particle size. Fine aggregate (BFS5-0.3) is preferable because it can be obtained as blast furnace slag particles having a maximum particle size of 5 mm or less only by classification by omitting the pulverization step.

《Blast furnace slow-cooled slag sand》
The blast furnace slow-cooled slag sand is prepared by gradually cooling and solidifying slag extracted from a blast furnace in a high-temperature molten state exceeding 1500 ° C. by air cooling and appropriate water spraying, and then adjusting to a predetermined particle size.
The blast furnace slow cooling slag contains a large amount of crystalline minerals such as gehlenite (2CaO.Al ₂ O ₃ .SiO ₂ ) having low latent hydraulic property due to slow cooling, so that the latent hydraulic property is lower than that of the blast furnace granulated slag. Low. Accordingly, in the case of mortar and concrete hardened bodies, when the latent hydraulic property is slowly exerted and crack self-healing performance is imparted over a long period of time, it is preferable to use the blast furnace slow-cooled slag as blast furnace slag particles.

As the blast furnace slow cooling slag, for example, hydraulic particle size adjusted steel slag (HMS25: particle size range = 25 to 0 mm) conforming to JIS A 5015 “steel slag for road”, particle size adjusted steel slag (MS-25: Particle size range = 25-0 mm), crusheran steel slag (CS-40: particle size range = 40-0 mm, CS-30: particle size range = 30-0 mm, CS-20: particle size range = 20 ˜0 mm) are pulverized and classified.
Among them, HMS-25, which is a hydraulic particle size-adjusted steel slag having a relatively small particle size, MS-25, which is a particle size-adjusted steel slag, and CS-20, which is a crusheran steel slag, can easily be obtained with a particle size of 5 mm or less by classification. Is particularly preferred.

  As the blast furnace slag particles, blast furnace granulated slag and blast furnace slow-cooled slag may be used alone or in combination.

The blast furnace slag particles used in the present embodiment contain 0.5% by mass or more of iron, preferably 0.5% by mass or more and 4.0% by mass or less, and more preferably 0.5% by mass or more and 2.% by mass. 5 mass% or less is included.
When the blast furnace slag particles contain the amount of iron in the above range, each component in the cement composition, water, oxygen and the iron react with each other, and various explosive precipitates such as iron oxide or iron hydroxide are produced. Generate. Therefore, the blast furnace slag particles containing the above amount of iron form a precipitate in the cracked portion when cracking occurs in the hardened cement body, and exert a crack healing effect. In addition, because the blast furnace slag particles contain the amount of iron in the above range, crack healing of the hardened cement body is enhanced, and at the same time, rust more than necessary is generated on the surface of the hardened cement body, and the appearance is not impaired. Furthermore, expansion and destruction of the cement hardened body due to expansion when iron is oxidized can be suppressed.

The iron is preferably contained in the blast furnace slag particles in the form of metallic iron or iron oxide such as maghemite (γ-Fe ₂ O ₃ ) and magnetite (Fe ₃ O ₄ ).
The iron oxide is preferably contained as an iron compound that can be recovered by magnetic separation from the viewpoint of easily healing the cracks.
Metallic iron or iron oxide (for example, maghemite (γ-Fe ₂ O ₃ ), magnetite (Fe ₃ O ₄ )) that can be recovered by magnetic separation is oxidized and water coexisted with water and oxygen. Since hematite (α-Fe ₂ O ₃ ) and goethite (goethite; α-FeOOH), which are expandable rusts, are generated, and the cracked portion can be closed, the blast furnace slag used in this embodiment Preferred as particles.

The iron content refers to, for example, mass% calculated based on an iron compound separated and recovered from blast furnace slag particles by magnetic separation by magnetic separation.
Specifically, 20 kg of completely dried blast furnace slag particles were coarsely pulverized using a pulverizer such as a horizontal brown pulverizer (disc mill), and JIS Z 8801-1 “test screen sieve part 1: made of metal” The test sieve specified in “Mesh Sieve” is passed through a sieve having a nominal aperture of 2.36 mm, and then a magnetic separator (for example, NJ-G-600 × 2, manufactured by Nippon Magnetic Sorting Co., Ltd., counter electrode type). And magnetic flux density of 2.7 Tesla) for 10 minutes (processing capacity: 120 kg / hour) to obtain a recovered material mainly composed of iron. After measuring the mass of the recovered material, the entire amount of the recovered material was pulverized using a disk-type vibration mill made of tungsten carbide, and JIS R 5204 “cement” using a wavelength dispersive X-ray fluorescence analyzer (WDXRF). The content of iron (FeO = divalent iron oxide equivalent) of the recovered material is measured by a powder briquette method in accordance with the “XRF analysis method”. From the mass of the recovered material and the content of iron (converted to FeO) in the recovered product, the mass% of iron (converted to FeO) in the blast furnace slag particles is calculated.
The magnetic separator is not particularly limited, but in addition to a counter-polar magnetic separator using a general permanent magnet or electromagnet, a drum-type magnetic separator, a pulley-type magnetic separator, and a suspended type. A magnetic separator or the like can be used.

The blast furnace slag particles containing the iron in the range may be selected, for example, by selecting the blast furnace slag particles containing the iron in the range by the magnetic separator or adjusting the iron content of the blast furnace slag particles. Etc.
As a method for adjusting the iron content of the blast furnace slag particles, for example, in the case of blast furnace slag particles whose iron content is less than the above range, it is recovered from another blast furnace slag particle by means such as magnetic separation. There is a method of adjusting by adding iron.
Alternatively, in the case of blast furnace slag particles whose iron content exceeds the above range, after reducing the iron content by means of iron recovery such as magnetic separation, the required amount of iron is returned and the iron content is reduced. For example, a method of adjusting to be in the above range may be used.

The blast furnace slag particles have a particle size of 5 mm or less, preferably 2.5 mm or less and 0.075 mm or more.
Since the particle diameter of the blast furnace slag particles is in the above range, the precipitation of expansive substances such as iron oxide and iron hydroxide by the iron occurs efficiently. In addition, when mixed with the stimulant, the amount of the stimulant that comes into contact with the blast furnace slag particles increases, a decrease in fluidity can be suppressed, and a relatively small amount of stimulant is blended in the cement admixture. Even in such a case, the crack self-healing effect is efficiently exhibited.
Further, as described later, when the stimulating material is attached so as to form a layer on the surface of the blast furnace slag particles, the stimulating material is more easily attached to the surface within the range of the particle diameter.

The particle size of the blast furnace slag particles is 5 mm or less, which is a test sieve specified in JIS Z8801-1 “Test Screen Sieve Part 1: Metal Mesh Screen” and has a nominal opening. It means that 90% by mass or more of particles that have passed through a 4.75 mm sieve are contained.
The particle size of the blast furnace slag particles being 2.5 mm or less and 0.075 mm or more is a test sieve defined in JIS Z8801-1 “Test Net Sieve Part 1: Metal Net Sieve”. , It means that 90% by mass or more of particles passing through a sieve having a nominal aperture of 2.36 mm and not passing through a sieve having a size of 75 μm are contained.

(Stimulant)
The stimulant contains at least one selected from the group consisting of calcium hydroxide, calcium oxide, calcium sulfate, aluminum sulfate, and lithium sulfate.
Calcium hydroxide, calcium oxide, calcium sulfate, aluminum sulfate, and lithium sulfate are all blast furnace slag stimulating components that promote the latent hydraulic properties of the blast furnace slag particles. That is, the blast furnace slag particles can exhibit a higher crack self-healing action by the action of the stimulating component of the stimulant.

As the stimulating component, calcium hydroxide and calcium sulfate are preferable, and it is particularly preferable to use calcium hydroxide and calcium sulfate in combination.
Calcium hydroxide and calcium sulfate can act as a stimulating component for inducing the latent hydraulic properties of blast furnace slag as described above, and at the same time, can exhibit crack healing properties as described below by coexisting in the stimulating material.

Calcium hydroxide contains calcium aluminate (3CaO.Al ₂ O ₃ = C ₃ A, CaO · Al ₂ O ₃ = CA, 12CaO · 7Al ₂ O ₃ = C ₁₂ A ₇ contained in cement in the presence of water. Hydration reaction. Of calcium hydroxide and calcium aluminate are reacted hydrated, _{firstly, CAH 10 (CaO · Al 2} O 3 · 10H 2 O), generates and _{C 2 AH 8 (2CaO · Al} 2 O 3 · 8H 2 O) Furthermore, the crystals are converted to hydro garnet (3CaO.Al ₂ O ₃ .6H ₂ O = C ₃ AH ₆ ) or hydrocalumite (3CaO.Al ₂ O ₃ .Ca (OH) ₂ .12H ₂ O = C Calcium aluminate hydrates such as ₄ AH ₁₃ ) are produced. The calcium aluminate hydrate alone does not exhibit expansibility, but when supplied with calcium sulfate (sulfate ion) and water, ettringite (3CaO.Al ₂ O ₃ .3CaSO ₄ .32H ₂ O), or Monosulfate (3CaO.Al ₂ O ₃ .CaSO ₄ .12H ₂ O) is produced. Since the ettringite and monosulfate are expandable products, the cracks can be closed when they are formed in the cracked portions of the mortar and concrete after curing. That is, by coexisting calcium hydroxide and calcium sulfate, the latent hydraulic properties of the blast furnace slag particles are promoted, and at the same time, the ettringite and monosulfate, which are expansive products themselves, are generated, thereby causing cracks. Can be occluded. Therefore, higher crack healing properties can be exhibited.

The calcium hydroxide, calcium oxide, calcium sulfate, aluminum sulfate, and lithium sulfate contained in the stimulating material of this embodiment as stimulating components are preferably in the form of particles each having a particle size of 0.1 mm or less.
When the particle diameter of each of the stimulating components is within the above range, it is preferable because it easily dissolves in water and easily acts as a stimulating material.

  The particle diameter of each stimulating component is 0.1 mm or less, which is a test sieve defined in JIS Z8801-1 “Test Net Sieve Part 1: Metal Net Sieve”. It means that 90% by mass or more of particles that have passed through a sieve having an opening of 100 μm are contained.

"Calcium hydroxide"
As calcium hydroxide, for example, commercially available products such as special slaked lime, No. 1 slaked lime, No. 2 slaked lime that conform to JIS R 9001 “industrial slaked lime” can be used.
Among them, it is preferable to use special slaked lime, No. 1 slaked lime, etc., which are inexpensive industrial slaked lime having a CaO content of 70% by mass or more and a maximum particle size of 0.1 mm (100 μm) or less.
Each of the calcium hydroxides may be used alone or in any combination.

The content of calcium hydroxide contained in the stimulant is preferably 10 to 90 parts by mass (100 parts by mass as Ca (OH) ₂ ) out of 100 parts by mass of the stimulant.
If the content of calcium hydroxide is in the above range, sufficient amount of calcium aluminate such as hydrocalumite is sufficiently stimulated to sufficiently stimulate the latent hydraulic properties of blast furnace slag particles and react with calcium aluminate in cement. It is preferable because a hydrate can be formed.

<Calcium oxide>
Calcium oxide includes quick lime (free calcium oxide) for making steel pellets, quick converter lime, hard calcined quick lime (hard calcined quick lime), super hard calcined quick lime, quick lime for soil improvement, agriculture or horticulture Commercial lime (CaO) such as quick lime for use, or shell ash produced by baking shells, steel slag, calcia clinker, ettringite expansion material that satisfies the standards of JIS A 6202 “Expansion material for concrete”, quick lime A system expansion material, an ettringite-quick lime system expansion material, etc. can be used.
Especially, since the hydration reaction rate is slower than normal quick lime, it is preferable to use cemented carbide quick lime. It is preferable to use the cemented carbide quicklime having a CaO content of 80% by mass or more and a maximum particle size of 0.1 mm (100 μm) or less.
The calcium oxide may be used alone or as a mixture in any combination.

Examples of the steelmaking slag include steelmaking slag containing quick lime (free calcium oxide) such as converter slag (dephosphorization slag) and electric furnace slag that are by-produced during steelmaking, and those containing free calcium oxide. It is done.
The steelmaking slag is preferably used after being pulverized to a maximum particle size of 0.1 mm (100 μm) or less using a pulverizer such as a ball mill. Further, the steelmaking slag may be used alone or mixed in any combination.

As said steelmaking slag, for example, single grain steelmaking slag conforming to JIS A 5015 “steel slag for road” (SS-20: particle size range = 20 to 13 mm, SS-13: particle size range = 13 to 5 mm) SS-5: particle size range = 5-2.5 mm), crusheran steel slag (CSS-30: particle size range = 30-0 mm, CSS-20: particle size range = 20-0 mm), converter Examples include pulverized and classified slag.
Since the converter slag tends to have a higher free calcium oxide content as the particle size is smaller, the converter slag containing 3% by mass or more of free calcium oxide is pulverized to a maximum particle size of 0.1 mm (100 μm) or less. Are preferably used.
Among the single grain steel slags, SS-5 having a small particle size is particularly preferable because it is easy to grind.

Quick lime (free calcium oxide) contained in the steelmaking slag is also called free lime (f-CaO), and reacts with water to change to calcium hydroxide showing high alkalinity. Therefore, the steelmaking slag is a potential of the blast furnace slag. It can be a stimulating component that stimulates hydraulic properties. Moreover, since free calcium oxide is accompanied by volume expansion when changing to calcium hydroxide, a cement admixture containing steelmaking slag containing such free calcium oxide as a stimulant can exhibit higher crack self-healing performance.
In addition to free calcium oxide, the steelmaking slag includes iron oxide such as dicalcium ferrite (2CaO · Fe ₂ O ₃ ), maghemite (γ-Fe ₂ O ₃ ), magnetite (Fe ₃ O ₄ ), metallic iron, and the like. contains. Accordingly, it reacts with water, oxygen, and the like, so that expandable iron hydroxide, iron-containing hydrates, and the like are deposited, so that higher crack self-healing performance can be exhibited.

Examples of the expansion material include ettringite-based (calcium sulfoaluminate-based) expansion materials, quicklime-based expansion materials, ettringite-calcium composite expansion materials, and active ingredients that are generally marketed as expansion materials for concrete. Auin = calcium sulfoaluminate (3CaO · 3Al ₂ O ₃ · CaSO ₄ ), free lime (CaO), free gypsum (CaSO ₄ ), non-fired expansion material component-containing material (gypsum, Auin, calcium oxide The powders are mixed in an arbitrary combination and mixing ratio, and are not subjected to a baking treatment after mixing), and iron powder-based expansion materials. These expansion materials are preferably adjusted to a maximum particle size of 0.1 mm (100 μm) or less.
Among them, it is stable and inexpensive to use commercial products of ettringite-based expansive material, quicklime-based expansive material, and ettringite-quicklime-complexed expansive material that satisfy the standards of JIS A 6202 “Expanding material for concrete”. This is preferable. Each of the inflatable materials may be used alone or in any combination.

The content of calcium oxide contained in the stimulant is preferably 10 to 90 parts by mass (mass part as CaO) out of 100 parts by mass of the stimulant.
If the content of calcium oxide is within the above range, the latent hydraulic properties of the blast furnace slag particles are sufficiently stimulated, and a sufficient amount of calcium aluminate hydrate is produced when reacting with calcium aluminate in cement. This is preferable.

<Calcium sulfate>
Examples of calcium sulfate include general industrial gypsum such as anhydrous gypsum, dihydrate gypsum, and hemihydrate gypsum. The industrial gypsum is either a natural product or a by-product (by-product gypsum during flue gas desulfurization, by-product gypsum during hydrofluoric acid production, by-product gypsum during phosphoric acid production, by-product gypsum during titanium oxide production, etc.). May be.
Among these, anhydrous gypsum is preferable because it has an SO ₃ content of 55% by mass or more, does not contain moisture, and is easily pulverized.
It is preferable to use the anhydrous gypsum adjusted to a maximum particle size of 0.1 mm (100 μm) or less. Furthermore, among the above anhydrous gypsum, it is particularly preferable to use one that has been finely pulverized until the Blaine specific surface area becomes 5000 m ² / g or more.
The calcium sulfate may be used alone or as a mixture in any combination.

The content of calcium sulfate contained in the stimulant is preferably 10 to 90 parts by mass (100 parts by mass as CaSO ₄ ) out of 100 parts by mass of the stimulant.
If the content of calcium sulfate is in the above range, hydrates such as ettringite in a sufficient amount to sufficiently snip the latent hydraulic properties of blast furnace slag particles and react with calcium aluminate to self-heal cracks. Is preferable.

《Aluminum sulfate》
Examples of aluminum sulfate include a general powdered or flaky industrial sulfuric acid band (aluminum sulfate = Al ₂ (SO ₄ ) ₃ ), a liquid sulfuric acid band dissolved in water, and the like.
These aluminum sulfates may be either aluminum sulfate having crystal water or anhydrous aluminum sulfate.
Among them, powdered anhydrous aluminum sulfate containing no crystallization water is preferable because it is easily pulverized, and one having a maximum particle size adjusted to 0.1 mm (100 μm) or less is particularly preferable.
Each of the aluminum sulfates may be used alone or in any combination.

The content of aluminum sulfate contained in the stimulating material is preferably 10 to 90 parts by mass out of 100 parts by mass of the slag stimulating material as solid content (anhydrous aluminum sulfate).
If the content of aluminum sulfate is within the above range, hydrates such as ettringite in a sufficient amount to sufficiently stimulate the latent hydraulic properties of blast furnace slag particles and to self-heal cracks by reacting with calcium aluminate. Is preferable.

《Lithium sulfate》
Examples of the lithium sulfate include general powdered or flaky industrial lithium sulfate (Li ₂ SO ₄ ), an aqueous lithium sulfate solution dissolved in water, and the like.
These lithium sulfates may be either lithium sulfate having crystal water or anhydrous lithium sulfate.
Among them, powdery lithium sulfate monohydrate having low hygroscopicity is preferable because it is easily pulverized, and one having a maximum particle size adjusted to 0.1 mm (100 μm) or less is particularly preferable.
Each of the lithium sulfates may be used alone or in any combination.

The content of lithium sulfate contained in the stimulant is preferably 10 to 90 parts by mass out of 100 parts by mass of the slag stimulant as solid content (anhydrous lithium sulfate).
If the content of lithium sulfate is in the above range, hydrates such as ettringite in an amount sufficient to sufficiently stimulate the latent hydraulic properties of blast furnace slag particles and to self-heal cracks by reacting with calcium aluminate. Is preferable.

"cement"
The stimulating material of the present embodiment may include cement.
When the stimulating material includes cement, the stimulating material is easily attached to the surface of the blast furnace slag particles when the blast furnace slag particles and the stimulating material are mixed.

Although it does not specifically limit as said cement, Portland cement, the mixed cement based on Portland cement, a super-hard-hardening cement, other well-known cements, etc. are mentioned.
Examples of the Portland cement include various Portland cements defined in JIS R 5210 “Portland cement” such as normal, early strength, very early strength, moderate heat, low heat, very early strength, and sulfate resistance.
As the mixed cement based on Portland cement, types A, B and C of blast furnace cement specified in JIS R 5211 “Blast Furnace Cement”, and Class A of silica cement specified in JIS R 5212 “Silica Cement”. , B type, C type, A type, B type, C type and the like of fly ash cement defined in JIS R 5213 “Fly ash cement”.
The ultra-fast curing cement, old JIS R 2511 alumina cement meets the standards of "alumina cement refractories" or _{11CaO · 7Al 2 O 3 · CaX} 2 ( halogen element such as X is F) based ultra rapid setting cement, Auin = calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) -based super-hard cement or the like.
Examples of other cements include ordinary ecocements defined in JIS R 5214 “Ecocement”.

Among the cements, early-strength Portland cement and super-early-strength Portland cement have a high Blaine specific surface area and a high alite (3CaO.SiO ₂ ) content, so that a stimulant is layered on blast furnace slag particles as described later. Is preferable because the strength of the stimulating material layer can be increased in a short time.
In addition, low heat Portland cement or moderately hot Portland cement is preferable because it contains belite (2CaO · SiO ₂ ), which has a slow hydration reaction, and can maintain the self-healing ability of cracks in blast furnace slag particles over a long period of time.
Alumina cement is preferable because it hardens quickly and can increase the strength of the stimulant layer in a short time. Among the alumina cements, a high alumina type alumina cement containing 55% by mass or more of alumina (Al ₂ O ₃ ) is particularly preferable because it can generate a large amount of hydrates such as expansive ettringite.

Furthermore, the cement may be used alone or in any combination.
Moreover, you may select the said cement from the said by the combination with the said calcium hydroxide, calcium oxide, calcium sulfate, aluminum sulfate, lithium sulfate which is a stimulating component.

For example, the cement combined with calcium hydroxide or calcium oxide is preferably an alumina cement containing a large amount of calcium aluminate.
Moreover, it is also preferable to use Portland cement as cement combined with calcium sulfate.

When an alumina cement containing a large amount of calcium aluminate is used as a cement to be combined with calcium hydroxide or calcium oxide, the calcium hydroxide or calcium oxide reacts with the alumina cement in the presence of water to produce hydrocalumite or hydrogarnet. To produce calcium aluminate hydrates. This calcium aluminate hydrate reacts with sulfate ions (SO ₄ ²⁻ ) supplied from cement and stimulating materials in the presence of water in the presence of water to produce expansive ettringite, so it has a crack healing effect. Get higher. On the other hand, unreacted calcium hydroxide acts as a stimulating agent for blast furnace slag particles, so that the crack healing effect is enhanced.

Cement combined with calcium sulfate, in the case of using Portland cement, the excess relative aluminate contained in the Portland cement _{(3CaO · Al 2 O 3,} 4CaO · Al 2 O 3 · Fe 2 O 3) sulfate Calcium can be added, and an expandable ettringite can be stably produced. In addition, when used in combination with a cement admixture containing a large amount of calcium aluminate hydrate such as hydrocalumite, unreacted calcium sulfate out of excess calcium sulfate is calcium aluminum in the presence of water in the cracked area. Since it reacts with the hydrate of hydrate to produce expansive ettringite, the crack healing effect is higher.
Moreover, calcium hydroxide by hydration of calcium silicates _{(3CaO · SiO 2, 2CaO ·} SiO 2) which is the main constituent minerals of Portland cement are produced in large quantities, calcium hydroxide, as a stimulus material of blast furnace slag particles Since it acts, the crack healing effect becomes high.

The cement may be used as a coarse powder (coarse) cement adjusted to a particle size larger than usual (for example, the maximum particle size is 50 to 300 μm and the Blaine specific surface area is 500 to 2000 cm ² / g). When such coarse cement is used, it is preferable because crack self-healing performance can be exhibited over a long period of time.

When the cement is blended with the stimulant, the cement is preferably blended so as to have a content of 10 to 90 parts by mass with respect to 100 parts by mass of the cement admixture.
If it is content of the said range, it will become easy to make the said stimulant adhere to the surface of blast furnace slag particle | grains, and a crack self-healing property can fully be exhibited.

"water"
The stimulating material of this embodiment may contain water.
By adding water to the stimulating material, the stimulating material can be easily attached to the surface of the blast furnace slag particles.
As the water, tap water, industrial water, ground water, river water, rain water, distilled water, high purity water for chemical analysis (ultra pure water, pure water, ion exchange water) and the like can be used. It is preferable not to contain organic substances, chloride ions, sodium ions, potassium ions and the like which adversely affect the reaction, mortar and concrete hardened body.
In particular, tap water or industrial water is preferable because it is inexpensive and stable in quality.

The amount of water is preferably in the range of 10 to 40 parts by mass with respect to 100 parts by mass of the stimulant.
When the amount of water is within the above range, the stimulant is easily attached to the surface of the blast furnace slag particles.

《Other ingredients》
The stimulation material of the present embodiment may contain other components as necessary. For example, various chemical admixtures for reducing the amount of water may be included.
As the chemical admixture, known water reducing agents such as liquid or powder water reducing agents, AE water reducing agents, high performance water reducing agents, and high performance AE water reducing agents that are commercially available for concrete or mortar can be used.
The chemical admixture is preferably contained in an amount of about 0.1 to 3.0 parts by mass as a solid content with respect to 100 parts by mass of the stimulant.

Other components include Na-bentonite, Ca-bentonite, sepiolite, attapulgite, talc, anorthite, alunite, calcium phosphate, sodium carbonate, sodium bicarbonate, calcium carbonate, magnesium carbonate, fly ash, amorphous silica Fine powder (silica fume), natural pozzolans such as siliceous white clay and tuff, and powder materials such as carbonic acid diamide may be included as auxiliary materials.
By adding these aids, the self-healing performance of cracks can be further improved.
The auxiliary materials can be used alone or in admixture in any amount.

The blast furnace slag particles and the stimulant contained in the cement admixture of the present embodiment may be mixed in a powder state, or the stimulant may be attached to the surface of the blast furnace slag particles. .
In the case of attaching the stimulating material to the surface of the blast furnace slag particles, the powdery stimulating material may be adhered to the surface of the blast furnace slag particles, or a paste-like stimulating material previously mixed with water or the like. Then, the surface of the blast furnace slag particles may be coated so that the stimulating material is adhered to form a layer on the surface of the blast furnace slag particles.

When the stimulant is attached in a layered manner on the surface of the blast furnace slag particles, it is more effective to crack even with a small amount of stimulant than mixing the stimulant and blast furnace slag particles in powder form. Self-healing effect can be demonstrated.
In addition, by coating the surface of the blast furnace slag particles with a layer of stimulant, when blended in a cement composition, the effect of increasing the fluidity can be obtained.
Further, when the stimulating material contains cement, the stimulating components such as calcium oxide, aluminum sulfate, and lithium sulfate are attached to the surface of the blast furnace slag particles in a state of being hardly soluble by the cement. Sometimes, it is possible to suppress a sudden hydration reaction of each of the stimulating components in the stimulating material and a decrease in the fluidity of the cement composition.

When the stimulating material is attached to form a layer on the surface of the blast furnace slag particles, the thickness of the layer is preferably an average thickness of 0.1 mm to 0.4 mm, more preferably 0.2 mm or more. 0.3 mm or less.
When the layer thickness of the stimulant is within the above range, a higher crack self-healing performance can be obtained, and a small amount of stimulant can be efficiently contributed to the reaction with water during crack healing. Can exist.

The method of measuring the thickness of the layer of the stimulating material when the stimulating material is adhered to the surface of the blast furnace slag particles so as to form a layer is as follows.
The blast furnace slag particles to which the stimulating material is adhered in a layer form are the test sieves defined in JIS Z8801-1 “Test Net Sieve Part 1: Metal Net Sieve” and have a nominal aperture of 100 μm (= And optionally 20 particles from the particles that remain on the sieve. A part of the layer of the stimulant is peeled off from the blast furnace slag particles taken out, and a cross-sectional image of the cross-section of the peeled layer of the stimulant is taken using an optical microscope or a digital microscope. The average of the measured values of a total of 40 places where the thickness of the layer of stimulating material at the places was measured is taken as the layer thickness.

The method for adhering the stimulant in a layered manner to the surface of the blast furnace slag particles is not particularly limited. For example, a method of spraying a liquid stimulant mixed with water onto the blast furnace slag particles, blast furnace slag particles A method of adding a powdery stimulant into the blast furnace slag particles while rolling and stirring the water and water, and a paste-like mixture containing water while rolling and stirring the blast furnace slag particles For example, a method of adding a stimulating material to adhere to the surface of blast furnace slag particles.
Alternatively, a method may be employed in which the powder material and the liquid material in the material of the stimulating material are alternately added to the blast furnace slag particles and stirred to adhere the stimulating material to the surface of the blast furnace slag particles.
For these adhering operations, general-purpose devices such as a stirring and mixing device (single-shaft mixer, biaxial mixer, etc.), a rolling mixing device (pan pelletizer, tilting barrel mixer, etc.) can be used.

The cement admixture of the present embodiment may include blast furnace slag particles to which different types of stimulants are attached.
For example, it may be a cement admixture containing the blast furnace slag particles with the stimulant containing calcium hydroxide attached to the surface and the blast furnace slag particles with the stimulant containing calcium sulfate attached to the surface. .

When the blast furnace slag particles having the stimulant containing calcium oxide adhered to the surface and the blast furnace slag particles having the stimulant containing calcium sulfate adhered to the surface are mixed, as described above Higher crack healing properties can be exhibited by the coexistence of calcium hydroxide and calcium sulfate.
Furthermore, in addition to the above-mentioned action due to the coexistence of calcium hydroxide and calcium sulfate, the stimulating material containing calcium hydroxide and the stimulating material containing calcium sulfate are attached to blast furnace slag particles, respectively. Mixing blast furnace slag particles into a cement admixture has the following advantages.

For example, when a cement containing a large amount of calcium aluminate typified by alumina cement is blended with the stimulating material of the present embodiment, the calcium aluminate reacts with calcium hydroxide, calcium sulfate and water in the stimulating material. Therefore, when cracks occur in the hardened mortar and concrete, unreacted calcium aluminate hydrate and calcium sulfate (sulfate) do not remain in the hardened body. It becomes difficult to block.
Therefore, particularly when alumina cement or the like is added to the stimulant, the stimulant containing calcium hydroxide and the stimulant containing calcium sulfate are individually attached to the blast furnace slag particles, respectively. By mixing, calcium aluminate or calcium aluminate hydrate and calcium sulfate are less likely to react directly until cracking occurs in the hardened mortar and concrete, and water is high. Can exhibit crack self-healing performance.

Cement admixture of the present embodiment, the Al ₂ O ₃ and SO _3, the molar ratio of SO ₃ for _{Al 2 O 3 (SO 3 /} Al 2 O 3) is 0.01 or more 27.4 or less, preferably, It is preferable to include 0.09 or more and 3.6 or less.

By molar ratio of SO ₃ for Al ₂ O ₃ in admixture falls within the above range, higher crack self-healing effect can be exhibited, and efficiently react with water occurs at the time of cracking, contribute to cracking healing Inflatable ettringite and the like are preferable because they are efficiently produced.

In particular, in the case of a cement admixture containing the blast furnace slag particles to which the stimulant containing calcium oxide is attached to the surface, and the blast furnace slag particles to which the stimulant containing calcium sulfate is attached to the surface, as the molar ratio of sO ₃ for _{Al 2 O 3 (sO 3 /} Al 2 O 3) is within the above range, and the blast furnace slag particles the stimulus material including the calcium oxide is deposited on the surface, the calcium sulfate It is preferable to mix the blast furnace slag particles on which the stimulating material is attached.

By molar ratio of SO ₃ for Al ₂ O ₃ in admixture falls within the above range, higher crack self-healing effect can be exhibited, and efficiently react with water occurs at the time of cracking, contribute to cracking healing Inflatable ettringite and the like are preferable because they are efficiently produced.

The stimulating material may be attached to the surface of the blast furnace slag particles as a single layer, or may be attached so as to form a plurality of layers of two or more layers.
By attaching the stimulating material so as to form a plurality of layers of two or more layers, it is possible to obtain higher crack self-healing performance by utilizing the characteristics of the stimulating material of each layer.
Further, the thickness of the slag stimulating material attached to the surface of the blast furnace slag particles can be easily adjusted.

As the cement admixture in which the stimulating material is adhered to the blast furnace slag particles so as to form the plurality of layers, for example, after the stimulating material containing the calcium hydroxide and the alumina cement is adhered to the surface of the blast furnace slag particles, calcium sulfate is used. And a stimulant comprising Portland cement, or a stimulant comprising calcium hydroxide and alumina cement after adhering the stimulant comprising calcium sulfate and Portland cement to the surface of the blast furnace slag particles, Furthermore, the blast furnace slag particle | grains etc. which were made to adhere are mentioned.
Alternatively, a cement admixture in which a plurality of stimuli, which are the same stimuli and in which the mixing ratio of cement in the stimulant is changed, is attached in multiple times to form a plurality of layers may be used.

"Cement composition"
Next, the cement composition containing the cement admixture of this embodiment will be described.
The cement composition of the present embodiment is a cement composition such as a mortar composition or a concrete composition.

  The cement composition of the present embodiment includes the cement admixture of the present embodiment described above and cement, and includes aggregates such as fine aggregate and coarse aggregate, water, and various other additives as necessary. You may go out.

"cement"
As the cement, various cements exemplified as the material for the stimulating material can be used.
The amount of cement contained in the cement composition of the present embodiment is preferably in the range of 100 to 300 parts by mass of cement with respect to 100 parts by mass of the cement admixture, for example.

"aggregate"
As the fine aggregate, land sand (mountain sand), sea sand, river sand, crushed sand, quartz sand, blast furnace slag fine aggregate, ferronickel slag fine aggregate, copper slag fine aggregate, electric furnace oxidation slag fine aggregate, Examples include ferrochrome fine aggregate, artificial light-weight fine aggregate, recycled fine aggregate, and molten slag fine aggregate.
Examples of the coarse aggregate include land gravel (mountain gravel), sea gravel, river gravel, crushed stone, blast furnace slag coarse aggregate, artificial lightweight coarse aggregate, recycled coarse aggregate, molten slag coarse aggregate and the like.
Note that coarse aggregates and fine aggregates can be distinguished in accordance with the screening test of JIS A 1102.

The amount of the fine aggregate and coarse aggregate contained in the cement composition of the present embodiment is preferably in the following range.
In the case of a cement composition for mortar, the amount of fine aggregate is 1000 to 1700 kg, preferably 1200 to 1500 kg per 1 m ^{3 of} mortar hardened body.
In the case of a cement composition for concrete, the amount of fine aggregate per 1 m ^{3 of} hardened concrete is 700 to 1000 kg, preferably 800 to 900 kg, and the amount of coarse aggregate is 800 to 1100 kg per 1 m ^{3 of} hardened concrete. Preferably, it is 850 to 950 kg.

《Cement admixture》
For example, in the case of a cement composition for mortar, the amount of the cement admixture contained in the cement composition of the present embodiment is 300 to 1600 kg, preferably 360 to 1500 kg, per 1 m ^{3 of} the mortar hardened body.
In the case of a cement composition for concrete, the amount of the cement admixture is 200 to 1000 kg, preferably 400 to 850 kg, per 1 m ^{3 of the} hardened concrete.
When the content of the cement admixture is within these ranges, the hardened cement body can be cured well, and the uncured blast furnace slag particles and the stimulant are sufficiently present in the hardened cement body. High crack self-healing performance when cracks occur after curing.

"water"
The cement composition of this embodiment may contain water.
The amount of the water is, for example, 5 to 50 parts by mass, preferably 10 to 30 parts by mass, with 100 parts by mass of the cement, cement admixture, and powder material such as aggregate blended as necessary. Part.
When the amount of water is in the above range, sufficient strength can be obtained in the case of a cured body, and high crack self-healing performance can be obtained.

  The hardened cement obtained from the cement composition of the present embodiment can self-heal such cracks even when cracks occur, for example.

The cement admixture or cement composition of the present embodiment is, for example, a concrete viaduct superstructure, floor slab bottom and pier / abutment side, tunnel lining concrete, concrete bottom and side such as agricultural waterway, office building or apartment, etc. Slabs and walls, tunnel segments, box culverts, retaining wall products such as L-shaped retaining walls, U-shaped structures, fume pipes, utility poles, concrete blocks, concrete panels, etc. It can be suitably used for structures that have been difficult to repair.
When cracks occur in these structures and water is supplied to the cracked parts by rain, snowfall, infiltration of groundwater, inflow of river water, seawater, etc., sprinkling, water injection operation, etc. This cement admixture causes a hydrate formation reaction with water and components in the cement, thereby effectively self-healing cracks.

In the case where cracks occur in the structure as described above, conventionally, repair work in which an organic or inorganic filling material is injected into the cracks is performed, or even if cracks occur, the structure is not affected. Thus, measures such as waterproofing and water stop work were taken on the hardened cement body. However, such repair work, waterproof work, water stop work, etc. are costly, and if waterproof work or water stop work is performed simultaneously with the hardened cement construction work, the construction period of the structure will be prolonged. . In particular, if the mortar or hardened concrete is a structure such as a tunnel, railway viaduct, or automobile viaduct, repair work for these cracks after the start of operation of the structure may result in traffic closure or suspension of service. It was necessary and very difficult.
Therefore, when the cement admixture and cement composition of this embodiment are used in such a structure, the crack self-healing material performance can be obtained without performing repair work, waterproof work, water stop work, etc. as described above. There is an advantage that can be obtained.

  Since the cement admixture or cement composition of the present embodiment can exhibit high crack self-healing performance, even a relatively large crack having a crack width of about 0.3 mm, which has been difficult to self-heal in the past, can be used. By using a cement admixture or a cement composition, it becomes possible to self-heal cracks well.

  The cement admixture and cement composition according to the present embodiment are as described above, but the embodiment disclosed this time should be considered as illustrative in all points and not restrictive. . The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

The equipment used in this example is as follows.
[Used equipment]
-Stainless steel test sieve (for blast furnace slag particle adjustment = classification, JIS Z 8801-1 compliant product, with calibration certificate, manufactured by Kansai Wire Mesh Co., Ltd., diameter 300 mm x height 60 mm: nominal aperture = 4.75 mm, 2.36 mm 3 types of 100μm are used)
・ Magnetic sorter (for iron content measurement and adjustment of blast furnace slag particles, NJ-G-600 × 2, manufactured by Nippon Magnetic Sorting Co., Ltd., counter electrode type, magnetic flux density 2.7 Tesla)
Horizontal Brown Crusher (1025-HC, manufactured by Yoshida Seisakusho, disk diameter 300 mm, disk material chrome carbide, with water cooling device, rotation speed 350-400 rpm, 200 V three-phase motor output 3.7 kW)
-Disc type vibration mill (9306D-KD, manufactured by Rigaku Corporation, sample grinding container material tungsten carbide, 200V three-phase motor output 2.2 kW)
・ Wavelength dispersive X-ray fluorescence analyzer (ZSX Primus II, manufactured by Rigaku)
・ Concrete tilt-cylinder mixer (NGM-4M22, manufactured by Dragonfly Industries Co., Ltd., capacity 100 liters, 200V three-phase motor output 2.2 kW)
・ Hand spray (Home Center Konan, polycarbonate, manual, 2 liter capacity)
・ Mortar mixer (Hobart mixer N-50, manufactured by Hobart Japan Co., Ltd., JIS R 5201, strength test conforming to “Cement physical test method”, 100V single phase motor output 125W)
・ Concrete mixer (SUPER DOUBLE MIXER SD-55, manufactured by Taihei Koki Co., Ltd., biaxial forced kneading mixer, capacity 55 liters, 200V three-phase motor output 3.7 kW)
-Mortar pressure tester (manufactured by Shimadzu Corporation, maximum loading capacity 300KN)
・ Concrete pressure tester (manufactured by Shimadzu Corporation, maximum loading capacity 3000KN)
Digital microscope (manufactured by Keyence Corporation, body = VHX-1000, lens = VH-Z100R wide range lens (magnification 100-1000 times))

(Blast furnace slag particles)
In this example, the following six types of blast furnace slag particles were prepared and used.
A) Blast furnace slag A
Shinko Sand (manufactured by Shinko Slag Products Co., Ltd., JIS A 501-1 BFS2.5 compliant product, maximum particle size 5 mm, absolute dry density = 2.74 g / cm ³ ) was used for the above stainless steel test sieve (nominal mesh 4 .75 mm), 120 kg of blast furnace slag A adjusted to a maximum particle size of 5 mm or less, an absolutely dry density = 2.74 g / cm ³ , and iron = 0.51 mass% was produced.
In this example, the iron content of each blast furnace slag particle was measured by the following method.
20 kg of absolutely dry blast furnace slag particles were coarsely pulverized using the horizontal brown pulverizer, passed through the stainless steel test sieve (nominal aperture 2.36 mm), and then the magnetic separator was used. A magnetic separation process was performed for 10 minutes (processing capacity of 120 kg / hour) to obtain a recovered material mainly composed of iron. After the mass is measured, the recovered material is pulverized in its entirety using the disk-type vibration mill, and conforms to JIS R 5204 “Cement X-ray fluorescence analysis method” using the wavelength dispersive X-ray fluorescence analyzer. Then, the iron (FeO equivalent) content of the recovered material was measured by a powder briquette method. The mass% of iron (FeO equivalent) in the blast furnace slag particles was calculated from the mass of the recovered substance and the content of iron (FeO equivalent) in the recovered substance.
B) Blast furnace slag B
Blast furnace slow-cooled slag (made by Shinko Slag Products Co., Ltd., particle size of less than 25 mm, absolutely dry density = 2.70 g / cm ³ ) is classified using the stainless steel test sieve (nominal aperture 4.75 mm). 20 kg of blast furnace slag B adjusted to a particle size of 5 mm or less, an absolutely dry density = 2.69 g / cm ³ , and iron = 0.65 mass% was produced.
C) Blast furnace slag C
Shinko Sand (manufactured by Shinko Slag Products Co., Ltd., JIS A 501-1 BFS2.5 compliant product, maximum particle size 5 mm, absolute dry density = 2.74 g / cm ³ ) was used for the above stainless steel test sieve (nominal mesh 4 .75 mm), and a recovered material containing iron recovered using a magnetic separator from a separately prepared blast furnace granulated slag is added to obtain a maximum particle size of 5 mm or less, an absolutely dry density = 20 kg of blast furnace slag C adjusted to 2.74 g / cm ³ and iron = 2.45% by mass was produced.
D) Blast furnace slag D
Blast furnace slow-cooled slag (made by Shinko Slag Products Co., Ltd., particle size of less than 25 mm, absolute dryness = 2.70 g / cm ³ ) is classified using the stainless steel test sieve (nominal opening 4.75 mm), A recovered material containing iron recovered from a separately prepared blast furnace slow-cooled slag using a magnetic separator is added, and the maximum particle size is 5 mm or less, the absolute dry density = 2.69 g / cm ³ , and iron = 1. 20 kg of blast furnace slag D adjusted to 37% by mass was produced.
E) Blast furnace slag E
Shinko Sand (manufactured by Shinko Slag Products Co., Ltd., JIS A 501-1 BFS2.5 compliant product, maximum particle size 5 mm, absolute dry density = 2.74 g / cm ³ ) was used for the above stainless steel test sieve (nominal mesh 4 .75 mm), and a recovered material containing iron recovered using a magnetic separator from a separately prepared blast furnace granulated slag is added to obtain a maximum particle size of 5 mm or less, an absolutely dry density = 20 kg of blast furnace slag E adjusted to 2.74 g / cm ³ and iron = 3.88% by mass was produced.
F) Blast furnace slag F
Shinko Sand (manufactured by Shinko Slag Products Co., Ltd., JIS A 501-1 BFS2.5 compliant product, maximum particle size 5 mm, absolute dry density = 2.74 g / cm ³ ) was used for the above stainless steel test sieve (nominal mesh 4 .75 mm), and a recovered material containing iron recovered using a magnetic separator from a separately prepared blast furnace granulated slag is added to obtain a maximum particle size of 5 mm or less, an absolutely dry density = 20 kg of blast furnace slag F adjusted to 2.75 g / cm ³ and iron = 4.23 mass% was produced.
(Silica sand)
Mixed silica sand (produced in Aichi Prefecture, dry silica sand No. 3 and No. 4 mixed by 50% by mass, maximum particle size of 5 mm or less, absolute dry density = 2.64 g / cm ³ , iron = 0.03 mass%) for comparative examples 20 kg was prepared.

(Stimulant)
Stimulation materials were prepared with the formulations shown in Table 1.
The materials used in Table 1 are as follows.
(1) Stimulation component a) Calcium hydroxide (JIS special slaked lime, manufactured by Yoshizawa Lime Industry Co., Ltd., JIS R 9001 compliant product, CaO content = 74.0 mass%, Al ₂ O ₃ content = 0.45 mass% SO ₃ content = less than 0.1% by mass, density = 2.34 g / cm ³ , Blaine specific surface area = 5000 cm ² / g, maximum particle size = 45 μm or less)
b) calcium oxide (carbide sintered lime, Yoshizawasekkaikogyo Co., CaO content = 95.2 wt%, Al ₂ O ₃ content = 0.78 wt%, SO ₃ content = less than 0.1 wt% Density = 3.32 g / cm ³ , specific surface area of brane = 4500 cm ² / g, maximum particle size = 45 μm or less)
c) Calcium sulfate (finely pulverized product of natural anhydrous gypsum, manufactured by Sumitomo Osaka Cement Co., Ltd., density = 2.97 g / cm ³ , CaO content = 41.1 mass%, Al ₂ O ₃ content = 0.1 mass) %, SO ₃ content = 56.7% by mass, Blaine specific surface area = 6800 cm ² / g, maximum particle size = 45 μm or less)
d) Aluminum sulfate (crushed product of reagent anhydrous aluminum sulfate, manufactured by Kanto Chemical Co., Inc., density = 2.71 g / cm ³ , Al ₂ O ₃ content = 28.7 mass%, SO ₃ content = 66.7 mass% Maximum particle size = 0.1 mm or less)
e) Lithium sulfate (reagent lithium sulfate monohydrate, manufactured by Kanto Chemical Co., Inc., density = 2.21 g / cm ³ , Al ₂ O ₃ content = less than 0.1 mass%, SO ₃ content = 71.8 mass %, Maximum particle size = 0.1 mm or less)
f) Steelmaking slag (pulverized product of converter slow-cooled slag containing quicklime (free calcium oxide), manufactured by Shinko Slag Products Co., Ltd., absolutely dry density = 2.74 g / cm ³ , CaO content = 51.8% by mass, f-CaO (free calcium oxide) content = 7.7 mass%, Al ₂ O ₃ content = 3.2 mass%, SO ₃ content = 1.0 mass%, maximum particle size = 0.1 mm or less)
g) Expanding material: Ettlingite-based expanding material Saks (manufactured by Sumitomo Osaka Cement Co., Ltd., JIS A 6202 compliant product, density = 2.98 g / cm ³ , CaO content = 52.2 mass%, Al ₂ O ₃ content = 13 9.9% by mass, SO ₃ content = 30.2% by mass, Blaine specific surface area = 3200 cm ² / g, maximum particle size = 45 μm or less)
(2) Cementy) Low heat Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd., JIS R 5210 compliant product, density = 3.24 g / cm ³ , C ₂ S content = 56 mass%, Al ₂ O ₃ content = 2.7) (Mass%, SO ₃ content = 2.0 mass%, Blaine specific surface area = 3400 cm ² / g, maximum particle size = 45 μm or less)
B) Alumina cement (Asahi Alumina Cement No. 1, manufactured by Asahi Glass Ceramics Co., Ltd., conforming to the former JIS R 2511, density = 2.99 g / cm ³ , Al ₂ O ₃ content = 55.0 mass%, CaO content = 35 3 mass%, SO ₃ content = 0.4 mass%, Blaine specific surface area = 4500 cm ² / g, maximum particle size = 45 μm or less)
C) Hayashi Portland Cement (manufactured by Sumitomo Osaka Cement Co., Ltd., JIS R 5210 compliant, density = 3.13 g / cm ³ , C ₃ S content = 65 mass%, Al ₂ O ₃ content = 5.0 mass%) SO ₃ content = 2.8% by mass, Blaine specific surface area = 4400 cm ² / g, maximum particle size = 45 μm or less)
(3) Water: Tap water (produced in Funabashi City, Chiba Prefecture)

(Cement admixtures A-1 to A-7)
After adding all the stimulants and blast furnace slag A prepared in the composition shown in Table 1 to the concrete tilting drum mixer (10 kg per batch), the drum angle of the tilting drum mixer is increased by 15 degrees from the horizontal, and 10 rpm at 40 rpm. Cement admixtures that were rotated for a minute and mixed in a dry state: 7 types (A-1 to A-7) were produced.

(Cement admixtures B-1 to B-12, C-1, D-1)
After all the blast furnace slag particles A to F are put into a concrete tilting drum mixer (10 kg per batch), the angle of the drum of the tilting drum mixer is increased by 15 degrees from the horizontal, and rotated at 40 rpm for 10 minutes. Cement admixtures in which each of the stimulants shown and water (sprayed by hand spray) are alternately added little by little, and one layer of the stimulant is adhered to the surface of the blast furnace slag particles: 14 types (B-1 to B-12, C-1, D-1) were produced. In addition, after adhering the stimulant, these were individually put in a polyethylene bag with a capacity of 50 liters, sealed, and cured in a 20 ° C. constant temperature room for 7 days.

(Cement admixture E-1, E-2)
For comparison, instead of blast furnace slag particles, the cement admixture E was mixed in the dry state in the same manner as the cement admixtures A-1 to A-7, using the silica sand and the stimulant shown in Table 1. -1 was produced.
Furthermore, using the silica sand and the stimulating material shown in Table 1, a cement admixture in which the stimulating material is adhered to the silica sand in the same manner as the cement admixtures B-1 to B-12, C-1, and D-1. E-2 was produced.

(Measurement of layer thickness)
The cement admixtures B-1 to B-12, C-1, D-1, and E-2 subjected to the curing are passed through a sieve having a nominal mesh size of 100 μm (= 0.1 mm) and 20 particles from the particles remaining on the sieve. Each piece of blast furnace slag particles is arbitrarily extracted, and using precision tweezers and a cutter knife, the cracked self-healing material attached to the blast furnace slag particles is peeled off, and the thickness of the cracked self-healing material is removed using a digital microscope. Using the image of the cut surface, the thickness (film thickness) of the cracked self-healing material adhering to the blast furnace slag particles was measured at two arbitrary locations, and the average value of a total of 40 locations was determined.
The average value of each thickness is shown in Table 1.

Using the cement compositions as shown in Table 2 and Table 3, concrete and mortar hardened bodies of Examples 1 to 56 and Comparative Examples 1 to 10 were produced and subjected to various tests.
In Examples 25 to 27 and Examples 53 to 55, a mixture of two types of cement admixtures shown in each table was used as a cement admixture.
Moreover, the compounding quantity of the cement admixture was mix | blended so that it might be an internal replacement with respect to a fine aggregate.
In addition, the density of each cement admixture was considered to be the same as that of the fine aggregate, and the formulation was not corrected. The high performance AE water reducing agent was considered part of the water.
The material of the cement composition for concrete and mortar hardened body is shown below.

Cement (common to mortar and concrete): Ordinary poldoland cement (manufactured by Sumitomo Osaka Cement Co., Ltd., JIS R 5210 compliant, density = 3.15 g / cm ³ , C ₃ S content = 56 mass%, C ₂ S content = 17% by mass, Al ₂ O ₃ content = 5.2% by mass, SO ₃ content = 1.9% by mass, Blaine specific surface area = 3400 cm ² / g, maximum particle size = 45 μm or less)
・ Fine aggregate (common to mortar and concrete): Land sand from Futtsu, Chiba (surface dry density = 2.58 g / cm ³ , water absorption = 2.1%, FM = 2.65)
・ Coarse aggregate for concrete: Hard sandstone crushed stone from Sakuragawa City, Ibaraki Prefecture 2005 (surface dry density = 2.65 g / cm ³ , water absorption rate = 0.6%, FM = 6.67)
・ Water (common to mortar and concrete): tap water ・ High performance AE water reducing agent (common to mortar and concrete): Leo Build SP8SVX2 (BASF Japan, polycarboxylic acid, JIS A 6204 high performance water reducing agent standard type I conformity Product)

(Mortar mixing and flow test)
The mortar flow was measured for the cement compositions of Examples 1 to 28 and Comparative Examples 1 to 5. The mortar kneading method was performed in accordance with the mortar test method of JIS R 5201 “Physical test method of Portland cement”.
Table 2 shows the results of immediately measuring the 15-stroke mortar flow in accordance with JIS R 5201 for each mortar that was kneaded.

(Mortar compressive strength test)
The compressive strength was measured for the cement compositions of Examples 1 to 28 and Comparative Examples 1 to 5. Each mortar whose flow was measured was returned to the kneading bowl of the mortar mixer, kneaded again for 30 seconds, and then poured into a simple steel form having a diameter of 5 cm × height of 10 cm to prepare four mortar cylindrical specimens. . The prepared cylindrical specimen was sealed in a 20 ° C. thermostatic chamber for 91 days in a sealed state using a polyethylene vinyl cap and a rubber band at the head (opening) of a simple steel mold. After curing for 91 days, all four specimens were removed from the mold, and three of them were used, using a pressure resistance tester, in accordance with JIS A 1108 “Concrete Compressive Strength Test Method”, with an age of 91 days The compressive strength was measured.
The results are shown in Table 2.

(Water resistance of mortar (water flow test))
The cement compositions of Examples 1 to 28 and Comparative Examples 1 to 5 were subjected to a water-stopping (water permeability) test. One of the specimens that was not used in the compressive strength test was split according to JIS A 1113 “Concrete Split Tensile Strength Test Method” and broken into two.
After splitting (breaking) a cylindrical specimen, two pieces of paraffin film having a length of 100 mm, a width of 5 mm, and a thickness of 0.3 mm were sandwiched between both end portions of the side of the cylinder and the two fracture surfaces were accurately aligned, Two steel bands of 45-55 mm variable type × width 9 mm × thickness 0.8 mm were used to constrain the outside (side surface part) of the cylindrical specimen and introduced into the cylindrical specimen using a digital microscope. By observing the crack width of the cracked part (measurement of the upper and lower surfaces of the specimen two at a time) and adjusting the tension of the steel band, the crack width of the upper and lower surfaces of the cylindrical specimen is about 0.2 to It adjusted so that it might become 0.3 mm. Thereafter, a pipe made of vinyl chloride having an inner diameter of 51 mm × height of 100 mm for water passage test is connected to the upper surface of the cylindrical specimen (on the upper side of the mold at the time of preparing the specimen), and the cylindrical specimen and the connecting portion of the pipe and the cylindrical specimen Sealing was performed by applying a commercially available sealing material (silicone rubber) to the cracked portion on the side of the specimen.
From the 91st day when the specimen was left standing vertically on a steel grating laid in a constant temperature room at 20 ° C and cracks were introduced by splitting, tap water was supplied to a pipe made of vinyl chloride connected to the upper part of the mortar cylindrical specimen. The water stoppage was measured for 7 days by giving a water head of 8 cm at all times and measuring the amount of water leakage from the crack of the mortar cylindrical specimen, and the following five levels of indicators were evaluated.

Evaluation of water stoppage due to self-healing of cracks ・ Initial water leakage amount = Water leakage amount for 5 minutes immediately after the start of water flow ・ Evaluation A: Water leakage amount for 5 minutes on the 7th day of the water flow test is 1% of the initial water leakage amount Case B / Evaluation B: Leakage amount per 5 minutes on the 7th day from the start of the water flow test is greater than 1% of the initial water leak amount and 5% or less / Evaluation C: 7 days from the start of the water flow test When the water leakage amount per 5 minutes of the eyes is greater than 5% of the initial water leakage amount and 10% or less ・ Evaluation D: The water leakage amount per 5 minutes on the 7th day of the water flow test is 10% of the initial water leakage amount When the water leak rate is less than 25% ・ Evaluation E: The water leak rate for 5 minutes on the 7th day of the water flow test cannot be less than 25% of the initial leak rate

(Evaluation of rusting on specimen surface)
In the compressive strength test, after sealing and curing in a 20 ° C. constant temperature room for 91 days, the surface of the removed specimen was visually observed, and rusting was confirmed. It was evaluated.
The results are shown in Table 2.

(SO ₃ / Al ₂ O ₃ molar ratio)
The molar ratio SO ₃ / Al ₂ O ₃ of all SO ₃ and all Al ₂ O ₃ contained in the cement admixtures of Examples 1 to 27 and Comparative Examples 1 to 6 was calculated and shown in Table 2.

  Table 2 shows the test results.

From Table 2 above, in each Example, the flow values when the cement admixture was added to the mortar were all good, and the 91-day compressive strength was also high. Further, the evaluation of water-stopping was as good as B or higher.
Since Comparative Example 1 is a mortar to which no cement admixture is added, it is clear that the evaluation of water-stopping due to self-healing is low.
Moreover, since Comparative Example 2 and 3 used what mixed silica sand instead of blast furnace slag particle | grains was used as a cement admixture, evaluation of the water stop by self-healing was low compared with the Example.
In Example 28, since the cement admixture B-12 containing blast furnace slag particles having an iron content of 4.23% by mass was used, there was a large amount of iron, and the cylindrical specimen was demolded at a material age of 91 days. A large number of spot-like red rusts were observed on the surface, and there was a problem with aesthetics.
In Comparative Examples 4 and 5, the stimulating component d (aluminum sulfate) and the stimulating component e (lithium sulfate) were blended as cement admixtures, respectively, so that the mortar was stiff rapidly and kneading itself was difficult, and a specimen could be produced. There wasn't.

(Mixing concrete, measuring slump and measuring air volume)
The slump and air amount of the cement compositions of Examples 29 to 56 and Comparative Examples 6 to 10 were measured.
First, as shown in Table 3, water cement mass ratio: 50% (unit water amount = 175 kg / m ³ ), s / a (fine aggregate ratio; absolute volume of fine aggregate ÷ (absolute volume of fine aggregate + The absolute volume of the coarse aggregate)) = 48.1% by volume was determined, and a high-performance AE water reducing agent was added to the cement in an amount of 0.8 to 2.0% by mass. Concrete of ± 3 cm and target air amount = 4.5 ± 1.5% was mixed in a constant temperature room at 20 ° C. in accordance with JIS A 1138 “How to make concrete in a test room” at 25 liters per batch.
Using fresh concrete that has been kneaded, use slump in accordance with JIS A 1101 “Testing method of concrete slump”, and measure the amount of air in accordance with JIS A 1128 “Testing method of fresh concrete using air pressure”. Was measured. The results are shown in Table 3.

(Concrete compressive strength test)
Using the fresh concretes of Examples 29 to 56 and Comparative Examples 6 to 10, they were driven into a simple steel form having a diameter of 10 cm and a height of 20 cm to prepare four concrete column specimens. The produced cylindrical specimen was sealed in a 20 ° C. constant temperature room for 28 days by sealing the head (opening) of the steel simple form using a polyethylene vinyl cap and a rubber band. After curing for 28 days, all four specimens were demolded, and three of them were measured for compressive strength at the age of 28 days in accordance with JIS A 1108 “Concrete compressive strength test method” using a pressure tester. did. The results are shown in Table 3.

(Waterproofing of concrete (water flow test))
One specimen not used in the compression test was subjected to a water-stopping (water permeability) test in the same manner as in Examples 1 to 28 and Comparative Examples 1 to 5.
However, the above-mentioned split (broken) cylindrical specimen is obtained by accurately aligning two fracture surfaces while sandwiching two paraffin films of length 200 mm × width 5 mm × thickness 0.3 mm between both ends of the cylinder. The steel band was restrained and fixed. Two steel bands having an inner diameter of 95 to 115 mm, a width of 12 mm, and a thickness of 0.8 mm were used as the steel bands for restraining the outside (side surface portion) of the cylindrical specimen. It adjusted so that the crack width of the surface part of a cylindrical specimen upper and lower surface might be set to about 0.2-0.3 mm. Further, a pipe made of vinyl chloride having an inner diameter of 106 mm and a height of 100 mm was used as the pipe connected to the upper surface of the cylindrical specimen (upper side of the mold when the specimen was manufactured).
Furthermore, water was injected from the age of 28 days when cracks were introduced by splitting, and the amount of water leakage from the cracks in the concrete cylindrical specimen was measured for 7 days, and the water-stopping evaluation was evaluated using the five-stage index. The results are shown in Table 3.

(SO ₃ / Al ₂ O ₃ molar ratio)
The molar ratio SO ₃ / Al ₂ O ₃ of all SO ₃ and all Al ₂ O ₃ contained in the cement admixtures of Examples 29 to 56 and Comparative Examples 6 to 10 was calculated and shown in Table 3.

From Table 3 above, in each example, both the slump and the air amount when the cement admixture was added to the concrete were good, and the 28-day compressive strength was also high. Further, the evaluation of water-stopping was as good as B or higher.
Since Comparative Example 6 is a concrete to which no cement admixture is added, it is clear that the evaluation of water stoppage due to self-healing is low.
In Comparative Examples 7 and 8, the water-stopping evaluation due to self-healing was lower than that in Examples using mixed silica sand instead of blast furnace slag particles.
In Example 56, since the cement admixture B-12 containing blast furnace slag particles having an iron content of 4.23 mass% was used, there was a large amount of iron, and the cylindrical specimen was demolded at the age of 91 days. A large number of spot-like red rusts were observed on the surface, and there was a problem with the appearance.
In Comparative Examples 9 and 10, the stimulating component d (aluminum sulfate) and the stimulating component e (lithium sulfate) were blended as cement admixtures, respectively. Therefore, the mortar was stiff rapidly and kneading itself was difficult, so that a specimen could be produced. There wasn't.

Claims (7)

Blast furnace slag particles containing 0.5 mass% or more of iron,
A cement admixture comprising a stimulant containing at least one selected from the group consisting of calcium hydroxide, calcium oxide, calcium sulfate, aluminum sulfate, and lithium sulfate.   The cement admixture according to claim 1, wherein the blast furnace slag particles contain 4.0 mass% or less of the iron.   The cement admixture according to claim 1 or 2, wherein the stimulating material is attached to a surface of the blast furnace slag particles.   The cement admixture according to any one of claims 1 to 3, wherein the stimulating material includes cement.   The cement blend according to claim 3 or 4, comprising the blast furnace slag particles having the stimulant containing calcium hydroxide attached to the surface and the blast furnace slag particles having the stimulant containing calcium sulfate attached to the surface. Wood. The stimulus material, wherein the Al ₂ O ₃ and SO _3, in any one of claims 1 to 5 molar ratio of SO ₃ for Al ₂ O ₃ contains such a 0.01 or 27.3 or less Cement admixture.   A cement composition comprising the cement admixture according to any one of claims 1 to 6.