JP2017024968A - Manufacturing method of cement hardening body using cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement composition having high flowability (for example 0 hit flow value of 200 mm or more) before curing and exhibiting high compressive strength (for example 350 N/mmor more) after curing.SOLUTION: There is provided a cement composition containing cement, silica fume with BET specific surface area of 15 to 25 m/g, inorganic power with 50% cumulative particle diameter of 0.8 to 5 μm, an aggregate A with maximum particle diameter of 1.2 mm or less, a high performance water-reducing agent, an antifoaming agent and water, with percentage of the cement of 55 to 65 vol.%, percentage of the silica fume of 5 to 25 vol.% and percentage of the inorganic powder of 15 to 35 vol.% in total amount 100 vol.% of the cement, the silica fume and the inorganic powder.SELECTED DRAWING: None

Description

  The present invention relates to a cement composition and a method for producing a hardened cementitious body using the cement composition.

In recent years, various cement compositions have been proposed that have good fluidity before curing and can exhibit high compressive strength after curing.
For example, Patent Document 1 discloses (A) cement, (B) fine powder having a BET specific surface area of 5 to 25 m ² / g, and (C) an inorganic powder having a brane specific surface area of 3,500 to 10,000 cm ² / g. , (D) fine aggregate, (E) water reducing agent, and (F) water, wherein the (D) fine aggregate is 2CaO · SiO ₂ and 2CaO · Al ₂ O _3. · containing SiO _2, relative to 2CaO · _SiO 2 100 parts by weight of a total amount of _{2CaO · Al 2 O 3 · SiO} 2 and _{4CaO · Al 2 O 3 · Fe} 2 O 3 is 10 to 100 parts by weight A cement composition is described, characterized in that it contains a fired product.
The cement composition has fluidity that can be applied before curing when the fired product contained in the fine aggregate is used in an absolutely dry state, and is high enough to exceed 250 N / mm ² after curing. When compressive strength is expressed and the fired product contained in the fine aggregate is used in a dry state, it has good fluidity before curing, and after curing has a high compressive strength of 200 N / mm ² or more. It is expressed and has a low self-shrinkage rate.

JP 2009-227574 A

In Patent Document 1, as an example in which the flow value was measured by “0 strike”, the mass ratio of water to the binder (water / binder mass ratio) was 0.135, and the zero strike flow value was 240 to 240. 242 mm, compressive strength of 280 N / mm ² cement composition, and water to binder mass ratio of 0.135, zero strike flow value of 270-275 mm, compressive strength of 215 N / mm A cement composition of ² is described.
The present invention has a high fluidity (for example, a zero stroke flow value of 200 mm or more) before curing, and a high compressive strength after curing (for example, when fine aggregate and coarse aggregate are used as aggregates. 300N / mm ² or more, and an object thereof is to provide a cement composition exhibiting a 350 N / mm ² or more) in the case of using only the fine aggregate as aggregate (the mortar or concrete).

As a result of intensive studies to solve the above problems, the present inventor has found that cement, silica fume having a BET specific surface area of 15 to 25 m ² / g, inorganic powder having a 50% cumulative particle size of 0.8 to 5 μm, maximum particle size Is a cement composition containing aggregate A having a diameter of 1.2 mm or less, a high-performance water reducing agent, an antifoaming agent, and water, wherein the cement, the silica fume, and the silica fume It has been found that the above object can be achieved by a cement composition in which each proportion of the inorganic powder is within a specific numerical range, and the present invention has been completed.
In addition, even when the cement composition includes aggregate B having a maximum particle size of more than 1.2 mm and not more than 13 mm, it has been found that a compressive strength of 300 N / mm ² or more can be expressed, and the present invention has been completed. did.

That is, the present invention provides the following [1] to [18].
[1] Cement, silica fume having a BET specific surface area of 15 to 25 m ² / g, inorganic powder having a 50% cumulative particle size of 0.8 to 5 μm, aggregate A having a maximum particle size of 1.2 mm or less, and a high-performance water reducing agent A cement composition containing an antifoaming agent and water, wherein the cement content is 55 to 65% by volume and the silica fume content is 5 to 5% in a total amount of 100% by volume of the cement, the silica fume and the inorganic powder. Cement composition characterized by 25 volume% and the ratio of the said inorganic powder being 15-35 volume%.
[2] The cement composition according to [1], wherein the cement composition does not include glass fiber.
[3] The cement composition according to [1] or [2], wherein an amount of the water is 10 to 20 parts by mass with respect to 100 parts by mass of the total amount of the cement, the silica fume, and the inorganic powder.
[4] The cement composition according to any one of [1] to [3], wherein the inorganic powder is one or more selected from the group consisting of quartz powder, volcanic ash, and fly ash.
[5] The cement composition contains one or more fibers selected from the group consisting of metal fibers, organic fibers, and carbon fibers, and the proportion of the fibers in the cement composition is 3% by volume or less. The cement composition according to any one of [1] to [4].
[6] The cement composition according to any one of [1] to [5], wherein the ratio of the aggregate A in the cement composition is 20 to 40% by volume.
[7] The cement composition according to any one of [1] to [6], wherein the aggregate A has a modified Mohs hardness of 9 or more.
[8] The cement composition according to any one of [1] to [7], wherein the compression strength after curing is 400 N / mm ² or more.
[9] The flow value before curing is 200 mm or more as a value measured without performing 15 drop motions in the method described in “JIS R 5201 (Cement physical test method) 11. Flow test”. The cement composition according to any one of [1] to [8].
[10] The cement composition according to any one of [1] to [5], wherein the cement composition includes an aggregate B having a maximum particle size of more than 1.2 mm and not more than 13 mm.
[11] The cement composition according to [10], wherein the ratio of the total amount of aggregate A and aggregate B in the cement composition is 25 to 40% by volume.
[12] The cement composition according to [10] or [11], wherein the compressive strength after curing is 300 N / mm ² or more.

[13] A method for producing a cementitious hardened body comprising the cement composition according to any one of [1] to [12], wherein the cement composition is placed in a mold, A molding step for obtaining an uncured molded body, and after curing the above-mentioned uncured molded body at 10 to 40 ° C. for 24 hours or more for sealing or aerating, the mold is removed from the mold and cured. About the room temperature curing process to be obtained and the cured molded body, either or both of steam curing or hot water curing at 70 ° C. or more and less than 100 ° C. for 1 hour or more and autoclave curing at 100 to 200 ° C. for 1 hour or more The above-mentioned cement is obtained by heating and curing the cured body after heating and curing, and heating the cured body after heating and curing at 150 to 200 ° C. for 24 hours or longer (excluding heating by autoclave curing). Hard A method for producing a cementitious hardened body comprising a high-temperature heating step for obtaining a chemicalized body.
[14] The method for producing a hardened cementitious material according to [13], further including a water absorption step for allowing the cured molded body to absorb water between the room temperature curing step and the heat curing step.
[15] The method for producing a cementitious cured body according to [14], wherein the cured molded body is immersed in water in the water absorption step.
[16] The method for producing a hardened cementitious body according to [15], wherein in the water absorption step, the cured molded body is immersed in water under reduced pressure.
[17] In the water absorption step, after the cured molded body is immersed in boiling water, the water temperature is cooled to 40 ° C. or less while the molded body is immersed. A method for producing a cementitious hardened body.
[18] In the normal temperature curing step, when the cured molded body expresses a compressive strength of ²⁰ to 100 N / mm ² , the cured molded body is demolded from the mold. A method for producing a hardened cementitious body according to any one of the above.

According to the cement composition (mortar) of the present invention, it has high fluidity (for example, zero-flow value is 200 mm or more) before curing, and high compressive strength (for example, 350 N / mm ² or more) after curing. ) Can be expressed. Moreover, according to the cement composition of the present invention, even a cement composition (concrete) containing coarse aggregate has high fluidity before curing, and has high compressive strength (for example, 300 N) after curing. / Mm ² or more).

The cement composition of the present invention is a cement, silica fume having a BET specific surface area of 15 to 25 m ² / g (hereinafter sometimes abbreviated as “silica fume”), inorganic powder having a 50% cumulative particle size of 0.8 to 5 μm. (Hereinafter, it may be abbreviated as “inorganic powder.”) A cement composition comprising aggregate A having a maximum particle size of 1.2 mm or less, a high-performance water reducing agent, an antifoaming agent, and water, and cement, silica fume And in the total amount of 100% by volume of inorganic powder, the proportion of cement is 55 to 65% by volume, the proportion of silica fume is 5 to 25% by volume, and the proportion of inorganic powder is 15 to 35% by volume.

The type of cement is not particularly limited. For example, various Portland cements such as ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement, moderately hot Portland cement, sulfate-resistant Portland cement, and low heat Portland cement are used. Can be used.
Among these, from the viewpoint of improving the fluidity of the cement composition, it is preferable to use moderately hot Portland cement or low heat Portland cement.

Silica fume has a BET specific surface area of 15 to 25 m ² / g, preferably 17 to 23 m ² / g, particularly preferably 18 to 22 m ² / g. When the specific surface area is less than 15 m ² / g, strength development of the cement composition decreases. When this specific surface area exceeds 25 m < ² > / g, the fluidity | liquidity of the cement composition before hardening falls.

Examples of the inorganic powder having a 50% cumulative particle size of 0.8 to 5 μm include quartz powder (silica powder), volcanic ash, fly ash (classified or pulverized), slag powder, limestone powder, feldspar powder, mullite Examples thereof include powder, alumina powder, silica sol, carbide powder, nitride powder, and pulverized product of emery sand (artificial or natural).
These may be used individually by 1 type and may be used in combination of 2 or more type.
Of these, quartz powder or fly ash is preferably used from the viewpoint of improving the fluidity and strength development of the cement composition.
In the present specification, cement is not included in the inorganic powder having a 50% cumulative particle size of 0.8 to 5 μm.

The 50% cumulative particle size of the inorganic powder is 0.8 to 5 μm, preferably 1 to 4 μm, more preferably 1.1 to 3.5 μm, particularly preferably 1.2 μm or more and less than 3 μm. When the particle size is less than 0.8 μm, the fluidity of the cement composition decreases. When the particle size exceeds 5 μm, the strength development of the cement composition is lowered.
In the present specification, the 50% cumulative particle size of the inorganic powder is based on volume.
The 50% cumulative particle size of the inorganic powder can be determined using a commercially available particle size distribution measuring device (for example, product name “Microtrac HRA Model 9320-X100” manufactured by Nikkiso Co., Ltd.).
Specifically, a cumulative particle size curve can be created using a particle size distribution measuring apparatus, and a 50% cumulative particle size can be obtained from the cumulative particle size curve. At this time, 0.06 g of a sample is added to 20 cm ^{3 of} ethanol, which is a solvent for dispersing the sample, and an ultrasonic dispersion apparatus (for example, product name “US300” manufactured by Nippon Seiki Seisakusho Co., Ltd.) is used for 90 seconds. Measure with ultrasonic dispersion.

The maximum particle size of the inorganic powder is preferably 15 μm or less, more preferably 14 μm or less, and particularly preferably 13 μm or less from the viewpoint of improving the strength development of the cement composition.
The 95% cumulative particle size of the inorganic powder is preferably 8 μm or less, more preferably 7 μm or less, and particularly preferably 6 μm or less from the viewpoint of improving the strength development of the cement composition.

As the inorganic powder, as a main component SiO ₂ is preferred. If the content of SiO ₂ in the inorganic powder is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more, the strength development of the cement composition is further improved. Can do.

In the cement composition of the present invention, in the total amount of 100% by volume of cement, silica fume and the inorganic powder, the proportion of cement is 55 to 65% by volume (preferably 57 to 63% by volume), and the proportion of silica fume is 5 to 25. The volume percentage (preferably 7 to 23 volume%) and the proportion of the inorganic powder are 15 to 35 volume% (preferably 17 to 33 volume%).
When the proportion of cement is less than 55% by volume, the strength development of the cement composition decreases. When the proportion of cement exceeds 65% by volume, the fluidity of the cement composition decreases.
When the proportion of silica fume is less than 5% by volume, the strength development property of the cement composition is lowered. When the proportion of silica fume exceeds 25% by volume, the fluidity of the cement composition decreases.
When the proportion of the inorganic powder is less than 15% by volume, the strength development of the cement composition is lowered. When the proportion of the inorganic powder exceeds 35% by volume, the fluidity of the cement composition decreases.

As aggregate A, river sand, mountain sand, land sand, sea sand, crushed sand, quartz sand, natural emery sand, artificial fine aggregate (for example, slag fine aggregate, fired fine aggregate obtained by firing fly ash, etc. And artificial emery sand, alumina or carbide (for example, silicon carbide, boron carbide), etc.), recycled fine aggregate or a mixture thereof.
The maximum particle size of the aggregate A is 1.2 mm or less, preferably 1.1 mm or less, more preferably 1.0 mm or less. If the maximum particle size is 1.2 mm or less, the strength development of the cement composition can be further improved, and a compressive strength of 300 N / mm ² or more (preferably 400 N / mm ² or more) can be developed. There are cases where it is possible.
The particle size distribution of the aggregate A is such that the ratio of the aggregate having a particle size of 0.6 mm or less is 95% by mass or more and 0.3 mm or less from the viewpoint of improving the fluidity and strength development of the cement composition. The ratio of the aggregate is preferably 40 to 50% by mass, and the ratio of the aggregate having a particle size of 0.15 mm or less is preferably 6% by mass or less.
The ratio of the aggregate A in the cement composition is preferably 20 to 40% by volume, more preferably 22 to 39% by volume, further preferably 25 to 38% by volume, still more preferably 30 to 37% by volume, and particularly preferably. 32 to 36% by volume. When the ratio is 20% by volume or more, the fluidity of the cement composition can be improved, the calorific value of the cement composition is reduced, and the shrinkage of the cementitious hardened body is reduced. If this ratio is 40 volume% or less, the strength development property of a cement composition can be improved.

As the high-performance water reducing agent, a high-performance water reducing agent such as naphthalene sulfonic acid, melamine, or polycarboxylic acid can be used. Among these, from the viewpoint of improving the fluidity and strength development of the cement composition, a polycarboxylic acid-based high-performance water reducing agent is preferable.
The compounding amount of the high-performance water reducing agent is preferably 0.2 to 1.5 parts by mass, more preferably 0.4, in terms of solid content, with respect to 100 parts by mass of the total amount of cement, silica fume and inorganic powder. -1.2 parts by mass. When the amount is 0.2 parts by mass or more, the water reduction performance is improved and the fluidity of the cement composition is improved. When the amount is 1.5 parts by mass or less, strength development of the cement composition is improved.

A commercial item can be used as an antifoamer.
The blending amount of the antifoaming agent is preferably 0.001 to 0.1 parts by weight, more preferably 0.01 to 0.07 parts by weight, particularly 100 parts by weight of the total amount of cement, silica fume and inorganic powder. Preferably it is 0.01-0.05 mass part. When the amount is 0.001 part by mass or more, the strength development of the cement composition is improved. When the amount exceeds 0.1 parts by mass, the effect of improving the strength development of the cement composition reaches its peak.

The cement composition of the present invention usually does not contain glass fibers from the viewpoint of avoiding a decrease in long-term strength.
In addition, the cement composition of the present invention is a group consisting of metal fibers, organic fibers, and carbon fibers from the viewpoint of improving the bending strength, fracture energy, etc. of a cured body (cemented cured body) obtained by curing the cement composition. One or more fibers selected from the above may be included. The proportion of fibers in the cement composition is preferably 3% by volume or less, more preferably 0.3 to 2.5% by volume, still more preferably 0.4 to 2.3% by volume, and particularly preferably 0.5 to 2.0% by volume. When the ratio is 3% by volume or less, the bending strength and fracture energy of the cured body can be improved without reducing the fluidity and workability of the cement composition.

Examples of metal fibers include steel fibers, stainless fibers, and amorphous fibers. Among these, steel fibers are excellent in strength, and are preferable from the viewpoints of cost and availability.
The dimensions of the metal fiber are 0.01 to 1.0 mm in diameter and 2 to 30 mm in length from the viewpoint of preventing material separation of the metal fiber in the cement composition and improving the bending strength of the cured body. The diameter is preferably 0.05 to 0.5 mm, and the length is more preferably 5 to 25 mm. Further, the aspect ratio (fiber length / fiber diameter) of the metal fiber is preferably 20 to 200, more preferably 40 to 150.
Furthermore, the shape of the metal fiber is preferably a shape that imparts some physical adhesion (for example, a spiral shape or a waveform) rather than a straight shape. In the case of a spiral shape or the like, the metal fiber and the matrix secure the stress while being pulled out, so that the bending strength of the cured body is improved.

The organic fiber only needs to be able to withstand the heating in the method for producing a cementitious cured body of the present invention to be described later. For example, aramid fiber, polyparaphenylenebenzobisoxazole fiber, polyethylene fiber, polyaryt fiber, polypropylene fiber, etc. Is mentioned.
Examples of the carbon fiber include PAN-based carbon fiber and pitch-based carbon fiber.
The dimensions of the organic fibers and carbon fibers are 0.005 to 1.0 mm in diameter and 2 to 30 mm in length from the viewpoint of preventing material separation of these fibers in the cement composition and improving the fracture energy of the cured body. Preferably, the diameter is 0.01 to 0.5 mm, and the length is 5 to 25 mm. Moreover, the aspect ratio (fiber length / fiber diameter) of the organic fiber and the carbon fiber is preferably 20 to 200, more preferably 30 to 150.

As water, tap water or the like can be used.
The amount of water is preferably 10 to 20 parts by mass, more preferably 12 to 18 parts by mass, and particularly preferably 14 to 16 parts by mass with respect to 100 parts by mass of the total amount of cement, silica fume and inorganic powder. When the amount is 10 parts by mass or more, the fluidity of the cement composition is improved. When the amount is 20 parts by mass or less, the strength development of the cement composition is improved.

The flow value before curing of the mortar composed of the above cement composition (without the aggregate B described later) is 15 times in the method described in “JIS R 5201 (physical test method for cement) 11. Flow test”. The value measured without performing the drop movement (hereinafter also referred to as “zero stroke flow value”) is preferably 200 mm or more, more preferably 210 mm or more, and particularly preferably 220 mm or more.
The compressive strength of the hardened cementitious material obtained by curing the mortar composed of the cement composition (not including the aggregate B described later) is preferably 320 N / mm ² or more, more preferably 350 N / mm ² or more. , even more preferably 400 N / mm ² or more, and particularly preferably 450 N / mm ² or more.
The aggregate A has a modified Mohs hardness of 9 or more (preferably 9 to 14, more preferably 9 to 13, still more preferably 10 to 13, particularly preferably 11 to 13) (for example, natural or artificial). According to a mortar (not including aggregate B, which will be described later) made of a cement composition using (manufactured) emery sand, alumina or carbide crushed material, etc., 450 N / mm ² or more (especially emery sand) When used, it is possible to develop a compressive strength of 500 N / mm ² or more.

The cement composition of the present invention can include aggregate B having a maximum particle size of more than 1.2 mm and 13 mm or less.
As aggregate B, river sand, mountain sand, land sand, sea sand, crushed sand, quartz sand, natural emery sand, artificial fine aggregate (for example, artificial emery sand, slag fine aggregate, fly ash, etc. are fired. Fired fine aggregate), recycled fine aggregate, river gravel, mountain gravel, land gravel, crushed stone, artificial coarse aggregate (for example, fired coarse aggregate obtained by firing slag coarse aggregate, fly ash, etc.), Recycled coarse aggregate or a mixture thereof may be used.
The maximum particle size of the aggregate B is 13 mm or less, preferably 12 mm or less, more preferably 11 mm or less, and particularly preferably 10 mm or less. When the maximum particle size is 13 mm or less, the strength development of the cement composition is improved, and for example, a compressive strength of 300 N / mm ² or more can be developed.
Further, the maximum particle diameter of the aggregate B is a value exceeding 1.2 mm from the viewpoint of cost reduction and the like, preferably 3 mm or more, more preferably 5 mm or more, and particularly preferably 7 mm or more.
In this specification, the “maximum particle size” when the maximum particle size of the aggregate B is 5 mm or more is the nominal size of the smallest size sieve among the sieves through which 90% by mass or more of the entire aggregate B passes. Is the particle size of the aggregate B (generally known as the definition of the maximum particle size of the coarse aggregate).

The minimum particle size of the aggregate B is preferably a value exceeding the maximum particle size of the aggregate A, more preferably 2 mm or more, further preferably 3 mm or more, further preferably 4 mm or more, particularly preferably 5 mm or more (in this case) Corresponds to coarse aggregate).
In the present specification, the minimum particle size of the aggregate B is the aggregate B as a whole when accumulated from the smallest particle size of the aggregate B toward the largest particle size. The particle size of the aggregate B when it reaches 15% by mass.

In the present invention, the ratio of the total amount of aggregate A and aggregate B in the cement composition is preferably 25 to 40% by volume, more preferably 30 to 38% by volume, and particularly preferably 32 to 36% by volume. . If this ratio is 25 volume% or more, the calorific value of a cement composition will become small and the shrinkage amount of a cementitious hardened body will become small. If this ratio is 40 volume% or less, the strength development property of a cement composition can be improved.
The ratio of the aggregate B to the total amount of the aggregate A and the aggregate B is preferably 40% by volume or less, more preferably 30% by volume or less. If this ratio is 40 volume% or less, the strength expression (for example, compressive strength) of a cement composition can be improved.
The compressive strength of the cementitious hardened body obtained by curing the cement composition (for example, concrete) containing the aggregate B is preferably 300 N / mm ² or more, more preferably 320 N / mm ² or more, and particularly preferably 340 N / mm. ² or more.

Hereafter, the manufacturing method of the cementitious hardened body formed by hardening | curing the cement composition of this invention is demonstrated in detail.
An example of a method for producing a hardened cementitious material according to the present invention includes a molding step of placing a cement composition in a mold to obtain an uncured molded body, and an uncured molded body at 10 to 40 ° C. After a sealing curing or air curing for at least 24 hours, the room temperature curing process for removing the mold from the mold and obtaining a cured molded body, and the cured molded body at a temperature of 70 ° C. or higher and lower than 100 ° C. for 1 hour or longer Curing or warm water curing and autoclave curing at 100 to 200 ° C. for 1 hour or more, or both, a heating curing step for obtaining a cured body after heating curing, and a cured body after heating curing are performed at 150 to 200. It includes a high-temperature heating step of obtaining a cementitious hardened body by heating at 24 ° C. for 24 hours or longer (excluding heating by autoclave curing).

[Molding process]
In this step, the cement composition is placed in a mold to obtain an uncured molded body.
The method of kneading the cement composition of the present invention before placing is not particularly limited. Moreover, the apparatus used for kneading is not particularly limited, and a conventional mixer such as an omni mixer, a pan-type mixer, a biaxial kneading mixer, and a tilting mixer can be used. Further, the placing (molding) method is not particularly limited.
The uncured molded body in this step may be made of a cement composition in which bubbles in the cement composition are reduced or removed. By reducing or removing air bubbles in the cement composition, the strength development of the cement composition can be further improved.
As a method of reducing or removing bubbles in the cement composition, (1) a method of kneading the cement composition under reduced pressure, (2) before placing the cement composition after kneading into a mold Examples thereof include a method for defoaming under reduced pressure, and (3) a method for defoaming under reduced pressure after placing the cement composition in a mold.

[Normal temperature curing process]
In this step, the uncured molded body is sealed at 10 to 40 ° C. (preferably 15 to 30 ° C.) for 24 hours or longer (preferably 24 to 72 hours, more preferably 24 to 48 hours). Then, it is a step of removing the mold from the mold and obtaining a cured molded body.
If the curing temperature is 10 ° C. or higher, the curing time can be shortened. When the curing temperature is 40 ° C. or less, the compressive strength of the cementitious cured body can be improved.
If the curing time is 24 hours or more, defects such as chipping and cracking are less likely to occur in the cured molded body during demolding.
Further, in this step, when the cured molded body exhibits a compressive strength of preferably ^{20 to} 100 N / mm ² , more preferably 30 to 80 N / mm ² , the cured molded body is removed from the mold. Is preferred. When the compressive strength is 20 N / mm ² or more, defects such as chipping and cracking are less likely to occur in the cured molded body during demolding. If the compressive strength is 100 N / mm ² or less, the cured molded body can absorb water with little effort in the water absorption step described later.

[Heat curing process]
In this step, the cured molded body obtained in the previous step is subjected to steam curing or hot water curing at 70 ° C. or more and less than 100 ° C. (preferably 75 to 95 ° C., more preferably 80 to 92 ° C.) for 1 hour or more. In this step, one or both of autoclave curing at 100 to 200 ° C. (preferably 160 to 190 ° C.) for 1 hour or more is performed to obtain a cured product after heat curing.
In this step, when only steam curing or warm water curing is performed, the curing time is preferably 12 hours or more, more preferably 24 to 96 hours, and particularly preferably 36 to 72 hours. When performing only autoclave curing, the curing time is preferably 2 hours or more, more preferably 3 to 60 hours, and particularly preferably 4 to 48 hours. When both steam curing or warm water curing and autoclave curing are performed (for example, when performing autoclave curing after performing steam curing or warm water curing), the curing time in steam curing or warm water curing is preferably 1 to 72 hours. More preferably, it is 2 to 48 hours, and the curing time in the autoclave curing is preferably 1 to 24 hours, more preferably 2 to 18 hours.
In this step, if the curing temperature is within the above range, the curing time can be shortened, and the compressive strength of the cementitious hardened body can be improved.
Further, in this step, when the curing time is within the above range, the compressive strength of the cementitious hardened body can be improved.

[High temperature heating process]
In this step, the cured body after heat curing is heated at 150 to 200 ° C. (preferably 170 to 190 ° C.) for 24 hours or longer (preferably 24 to 72 hours, more preferably 36 to 48 hours), and heating (however, autoclave This is a process for obtaining a cementitious hardened body by excluding heating by curing.
The heating in this step is usually performed under a dry atmosphere (in other words, a state where water and water vapor are not artificially supplied).
If the heating temperature is 150 ° C. or higher, the heating time can be shortened. If heating temperature is 200 degrees C or less, the compressive strength of a cementitious hardened body can be improved.
When the heating time is 24 hours or more, the compressive strength of the cementitious cured body can be improved.

[Water absorption process]
Between the room temperature curing process and the heat curing process, a water absorption process of absorbing water in the cured molded body obtained in the room temperature curing process may be included.
Examples of the method for causing the cured molded body to absorb water include a method for immersing the molded body in water. Further, in the method of immersing the molded body in water, from the viewpoint of increasing the amount of water absorption in a short time and increasing the compressive strength of the cementitious cured body, (1) immersing the molded body in water under reduced pressure. (2) A method of lowering the water temperature to 40 ° C. or lower while the molded body is immersed, after the molded body is immersed in boiling water, and (3) the molded body A method of immersing the molded body in boiling water and then removing the molded body from the boiling water and then immersing the molded body in water of 40 ° C. or lower; (4) the molded body under pressure A method of immersing the molded body in water or (5) a method of immersing the molded body in an aqueous solution in which a chemical that improves the water permeability to the molded body is dissolved is preferred.

Examples of the method for immersing the molded body in water under reduced pressure include a method using equipment such as a vacuum pump and a large-sized vacuum container.
Examples of the method for immersing the molded body in boiling water include a method using facilities such as a high-temperature and high-pressure vessel and a hot and cold water tank.
The time for immersing the cured molded body in water under reduced pressure or boiling water is preferably 3 minutes or more, more preferably 8 minutes or more, particularly preferably 20 minutes, from the viewpoint of increasing the water absorption rate. That's it. The upper limit of the time is preferably 60 minutes, more preferably 45 minutes, from the viewpoint of increasing the compressive strength of the cementitious cured body.

The water absorption rate in the water absorption process is determined when the cement composition does not contain coarse aggregate (when the cement composition does not contain aggregate B, or when the aggregate B in the cement composition does not correspond to coarse aggregate). The ratio of water with respect to 100% by volume of the cured molded body having a diameter of 50 × 100 mm is preferably 0.2% by volume or more, more preferably 0.3 to 2.0% by volume, particularly preferably 0.35 to 1.7% by volume. %, And when the cement composition contains coarse aggregate (when aggregate B in the cement composition corresponds to coarse aggregate), the ratio of water to 100 volume% of a cured molded body of φ100 × 200 mm is as follows: Preferably it is 0.2 volume% or more, More preferably, it is 0.3-2.0 volume%, Most preferably, it is 0.35-1.7 volume%.
If these water absorption is 0.2 volume% or more, the compressive strength of a cementitious hardened body can be raised more.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[Materials used]
The materials used are as shown below.
(1) Cement: Low heat Portland cement (manufactured by Taiheiyo Cement)
(2) Silica fume A: BET specific surface area of 20 m ² / g
(3) Silica fume B: BET specific surface area of 17 m ² / g
(4) Inorganic powder A: silica powder, 50% cumulative particle size 2 μm, maximum particle size 12 μm, 95% cumulative particle size 5.8 μm
(5) Inorganic powder B: silica powder, 50% cumulative particle size 7 μm, maximum particle size 67 μm, 95% cumulative particle size 27 μm
(6) Aggregate A1 (fine aggregate): Silica sand (maximum particle size 1.0 mm, particle size of 0.6 mm or less: 98% by mass, particle size of 0.3 mm or less: 45% by mass, 0 .15 mm or less particle size: 3% by mass)
(7) Aggregate A2 (fine aggregate): artificial emery sand (manufactured by Ujiden Chemical Co., Ltd., modified Mohs hardness: 12) (maximum particle size 1.0 mm, particle size of 0.6 mm or less: 96 mass% , With a particle size of 0.3 mm or less: 46% by mass, with a particle size of 0.15 mm or less: 1% by mass, with the particle size distribution adjusted)
(8) Polycarboxylic acid-based high-performance water reducing agent: solid content 27.4% by mass, manufactured by Floric, trade name “Floric SF500U”
(9) Antifoaming agent: BASF Japan, trade name “Master Air 404”
(10) Water: tap water (11) Metal fiber: Steel fiber (diameter: 0.2 mm, length: 15 mm)
(12) Aggregate B (coarse aggregate): hard sandstone crushed stone 1005 (particle size: 5-10 mm)

[Example 1]
Cement, silica fume A, and inorganic powder A were mixed so that the proportions of cement and the like would be the proportions shown in Table 1 in a total amount of 100 vol% of the powder raw materials (cement, silica fume, and inorganic powder). The obtained mixture and the aggregate A1 in such an amount that the ratio of the aggregate A1 in the cement composition is the ratio shown in Table 1 were put into an omnimixer and air-kneaded for 15 seconds.
Next, water, a polycarboxylic acid-based high-performance water reducing agent, and an antifoaming agent were added to the omni mixer in the amounts shown in Table 1, and kneaded for 2 minutes.
After kneading, the kneaded material adhering to the side wall in the omni mixer was scraped off and further kneaded for 4 minutes.
The flow value of the cement composition after kneading was measured in the method described in “JIS R 5201 (Cement physical test method) 11. Flow test” without performing 15 drop motions. In the present specification, the flow value is referred to as a “zero hit flow value”.

The obtained kneaded product was cast into a cylindrical mold having a diameter of 50 × 100 mm to obtain an uncured molded body. After casting, the uncured molded body was sealed and cured at 20 ° C. for 48 hours, and then demolded to obtain a cured molded body. The compressive strength at the time of demolding was 50 N / mm ² .
The molded body was immersed in water in a reduced pressure desiccator for the time shown in Table 2 (described as “under reduced pressure” in Table 2). The pressure reduction was performed using “Aspirator (AS-01)” manufactured by ASONE. The mass of the molded body before and after the immersion was measured, and the water absorption was calculated from the obtained measured value.
After the immersion, the molded body was subjected to steam curing at 90 ° C. for 48 hours, and then cooled to 20 ° C., and then heated at 180 ° C. for 48 hours without artificially supplying water or water vapor.
Moreover, the compressive strength of the obtained cementitious hardened body was measured according to “JIS A 1108 (Method for testing compressive strength of concrete)”. The compressive strength was measured using a 100t universal testing machine (hydraulic) manufactured by Shimadzu Corporation.

[Example 2]
A cement composition and its cured body (molded body) were obtained in the same manner as in Example 1 except that the amount of water per 100 parts by weight of the powder raw material was changed from 13 parts by weight to 15 parts by weight.
In the same manner as in Example 1, the zero-flow value of the cement composition was measured. The compressive strength at the time of demolding was 45 N / mm ² .

[Example 3]
Instead of immersing the molded body after demolding in water in a reduced-pressure desiccator, the molded body was immersed in boiling water (boiling water) for the time shown in Table 2, and then the molded body was immersed in water. A cement composition and a cured product thereof were obtained in the same manner as in Example 1 except that the water temperature was 25 ° C.
In the same manner as in Example 1, the water absorption rate was calculated and the compressive strength of the cementitious hardened body was measured.
[Example 4]
Instead of immersing the molded article after demolding in water in a reduced-pressure desiccator, the cement composition and the cement composition and The cured body (molded body) was obtained.
In the same manner as in Example 1, the water absorption rate was calculated and the compressive strength of the cementitious hardened body was measured.

[Example 5]
Cement composition as in Example 1, except that the amount of silica fume A is changed from 10% by volume to 20% by volume and the amount of inorganic powder A is changed from 30% by volume to 20% by volume. And the hardening body (molded object) was obtained.
In the same manner as in Example 1, the measurement of the zero-flow value was performed. The compressive strength of the molded body at the time of demolding was 50 N / mm ² .
[Example 6]
Instead of immersing the molded product after demolding in water in a reduced-pressure desiccator, the cement composition and the cement composition were obtained in the same manner as in Example 5 except that immersion in boiling water was performed in the same manner as in Example 3. The cured body (molded body) was obtained.
In the same manner as in Example 1, the water absorption rate was calculated and the compressive strength of the cementitious hardened body was measured.

[Example 7]
Cement composition as in Example 2 except that the amount of silica fume A is changed from 10% by volume to 20% by volume and the amount of inorganic powder A is changed from 30% by volume to 20% by volume. And the hardening body (molded object) was obtained.
In the same manner as in Example 1, the measurement of the zero-flow value was performed. The compressive strength of the molded product at the time of demolding was 45 N / mm ² .
[Example 8]
Instead of immersing the molded body after demolding in water in a reduced-pressure desiccator, the cement composition and the cement composition were obtained in the same manner as in Example 7 except that immersion in boiling water was performed in the same manner as in Example 3. The cured body (molded body) was obtained.
In the same manner as in Example 1, the water absorption rate was calculated and the compressive strength of the cementitious hardened body was measured.

[Example 9]
Cement, silica fume A, and inorganic powder A were mixed so that the proportions of cement and the like would be the proportions shown in Table 1 in a total amount of 100 vol% of the powder raw materials (cement, silica fume, and inorganic powder). The obtained mixture and the aggregate A1 in such an amount that the ratio of the aggregate A1 in the cement composition is the ratio shown in Table 1 were put into an omnimixer and air-kneaded for 15 seconds.
Next, water, a polycarboxylic acid-based high-performance water reducing agent, and an antifoaming agent were added to the omni mixer in the amounts shown in Table 1, and kneaded for 2 minutes.
After kneading, the kneaded material adhering to the side wall in the omni mixer is scraped off, and further kneaded for 4 minutes, and then the amount of metal fibers in the cement composition in the proportion shown in Table 1 is added to the omni mixer. The mixture was added and kneaded for another 2 minutes.
About the obtained cement composition, it carried out similarly to Example 1, and measured the zero flow value.
Moreover, the cementitious hardened | cured material (molded object) was obtained by the method similar to Example 1 using the obtained cement composition as a material.
About the obtained cementitious hardened | cured material (molded object), it carried out similarly to Example 1, and measured the water absorption rate and the compressive strength.
Furthermore, the bending strength of the obtained cementitious hardened body was measured according to “Japan Society of Civil Engineers standard JSCE-G 552-2010 (bending strength and bending toughness test method of steel fiber reinforced concrete)”.

[Example 10]
Instead of immersing the molded body after demolding in water in a reduced-pressure desiccator, the cement composition and the cement composition were obtained in the same manner as in Example 9 except that immersion in boiling water was performed in the same manner as in Example 3. The cured product was obtained.
About a cement composition and its hardened | cured material, it carried out similarly to Example 9, and measured various physical properties.

[Example 11]
The amount of water per 100 parts by mass of the powder raw material is changed from 13 parts by mass to 11 parts by mass, and the amount of the aggregate A1 is changed from 35.5% by volume to 30.0% by volume. The cement composition and the hardened cementitious body in the same manner as in Example 1 except that the blending amount of the agent was changed from 0.69 parts by mass to 0.76 parts by mass and the molded body was not immersed in water. Got.
In the same manner as in Example 1, the zero-flow value of the cement composition was measured. The compressive strength at the time of demolding was 54 N / mm ² .

[Example 12]
The molded body after demolding was immersed in boiling water (boiling water) for the time shown in Table 2, and then cooled until the water temperature reached 25 ° C. while the molded body was immersed in water. In the same manner as in Example 11, a cement composition and its cured body were obtained.
In the same manner as in Example 1, the water absorption rate was calculated and the compressive strength of the cementitious cured body was measured.

[Example 13]
The amount of aggregate A1 is changed from 30.0% by volume to 24.0% by volume, and aggregate B is used in such an amount that the ratio of aggregate B in the cement composition is 6.0% by volume. Prepared a cement composition having the same composition as the cement composition of Example 11.
The cement composition was manufactured in the same manner as in Example 1, after kneading each material (powder raw material, aggregate A1, water, polycarboxylic acid-based high-performance water reducing agent, and antifoaming agent), and further aggregate. B was put into an omni mixer and kneaded for 1 minute.
The obtained cement composition (kneaded material) was cast into a cylindrical mold of φ100 × 200 mm, and the cementitious hardening was performed in the same manner as in Example 1 except that the molded body was not immersed in water. Got the body.
The compressive strength of the cementitious cured body was measured in the same manner as in Example 1. The compressive strength at the time of demolding was 43 N / mm ² .

[Example 14]
The amount of aggregate A1 was changed from 35.5% to 28.5% by volume, and aggregate B was used in such an amount that the ratio of aggregate B in the cement composition was 7.0% by volume. Prepared a cement composition having the same composition as the cement composition of Example 8.
The cement composition was manufactured in the same manner as in Example 1, after kneading each material (powder raw material, aggregate A1, water, polycarboxylic acid-based high-performance water reducing agent, and antifoaming agent), The material B was put into an omni mixer and kneaded for 1 minute.
A hardened cementitious material was obtained in the same manner as in Example 8 except that the obtained cement composition (kneaded material) was cast into a cylindrical mold with a diameter of 100 mm x 200 mm.
In the same manner as in Example 8, the water absorption was calculated and the compressive strength of the cementitious hardened body was measured. The compressive strength at the time of demolding was 37 N / mm ² .

[Example 15]
A cement composition and its cured body (molded body) were obtained in the same manner as in Example 4 except that the aggregate A2 was used instead of the aggregate A1.
In the same manner as in Example 1, measurements such as a zero strike flow value of the cement composition were performed. The compressive strength at the time of demolding was 47 N / mm ² .

[Example 16]
A cement composition and its cured body (molded body) were obtained in the same manner as in Example 12 except that the aggregate A2 was used instead of the aggregate A1.
In the same manner as in Example 1, measurements of the zero-flow value and the like of the cement composition were performed. As a result, the compressive strength exceeded the measurement limit (511 N / mm ² ). The compressive strength at the time of demolding was 55 N / mm ² .

[Comparative Example 1]
Cement, silica fume B, and inorganic powder B were mixed so that each ratio of cement and the like would be the ratio shown in Table 1 in a total amount of 100 vol% of the powder raw materials (cement, silica fume and inorganic powder). The obtained mixture and the aggregate A1 in such an amount that the ratio of the aggregate A1 in the cement composition is the ratio shown in Table 1 were put into an omnimixer and air-kneaded for 15 seconds.
Next, water, a polycarboxylic acid-based high-performance water reducing agent, and an antifoaming agent were added to the omni mixer in the amounts shown in Table 1, and kneaded for 2 minutes.
After kneading, the kneaded material adhering to the side wall in the omni mixer was scraped off and further kneaded for 4 minutes.
Using the obtained kneaded material as a material, a cementitious cured body was obtained in the same manner as in Example 1. About the obtained kneaded material (cement composition) and its hardened | cured material, it carried out similarly to Example 1, and measured various physical properties.
The results are shown in Table 2.

From Table 2, it can be seen that according to the cement composition of the present invention (Examples 1 to 16), the zero-flow value is 217 mm or more. Moreover, it turns out that the compressive strength of the cementitious hardened | cured material formed by hardening | curing the cement composition of this invention is 350 N / mm < ² > or more, and is very large.
Moreover, it turns out that the bending strength of the cement composition (Examples 9-10) containing a metal fiber is 40 N / mm < ² > or more, and is large.
Moreover, it turns out that the compressive strength of the cement composition (Examples 15-16) using the fine aggregate whose correction Mohs hardness is 12 is 500 N / mm < ² > or more, and is extremely large.
Furthermore, it can be seen that the compressive strength of the cementitious hardened body obtained by hardening the cement composition containing coarse aggregate (Examples 13 to 14) is 333 N / mm ² or more.
On the other hand, in the comparative example 1, it turns out that the compressive strength of a cementitious hardened body is 290 N / mm < ² >, and is small compared with Examples 1-16.

In Patent Document 1, as an example in which the flow value was measured by “0 strike”, the mass ratio of water to the binder (water / binder mass ratio) was 0.135, and the zero strike flow value was 240 to 240. 242 mm, compressive strength of 280 N / mm ² cement composition, and water to binder mass ratio of 0.135, zero strike flow value of 270-275 mm, compressive strength of 215 N / mm A cement composition of ² is described.
The present invention has a high fluidity (for example, a zero stroke flow value of 200 mm or more) before curing, and a high compressive strength after curing (for example, when fine aggregate and coarse aggregate are used as aggregates. It is an object to provide a method for producing a cementitious hardened body made of a cement composition (mortar or concrete) that expresses 300 N / mm ² or more, and when using only a fine aggregate as an aggregate, 350 N / mm ² or more. To do.

As a result of intensive studies to solve the above problems, the present inventor has found that cement, silica fume having a BET specific surface area of 15 to 25 m ² / g, inorganic powder having a 50% cumulative particle size of 0.8 to 5 μm, maximum particle size Is a cement composition containing aggregate A having a diameter of 1.2 mm or less, a high-performance water reducing agent, an antifoaming agent, and water, wherein the cement, the silica fume, and the silica fume A molding step of placing a cement composition in which each proportion of the inorganic powder is within a specific numerical range in a mold to obtain an uncured molded body, and the uncured molded body under a specific condition A normal temperature curing process for obtaining a molded product that has been cured after sealing or in-air curing and then demolded, and for the cured product, steam curing or hot water curing under specific conditions, and autoclave under specific conditions A heat curing step for obtaining a cured product after heat curing by performing one or both of curing, and high-temperature heating for heating the cured product after the heat curing under specific conditions to obtain the cemented cured product According to the method for producing a hardened cementitious body comprising the steps, the inventors have found that the above object can be achieved and completed the present invention.
In addition, even when the cement composition includes aggregate B having a maximum particle size of more than 1.2 mm and not more than 13 mm, it has been found that a compressive strength of 300 N / mm ² or more can be expressed, and the present invention has been completed. did.

That is, the present invention provides the following [1] to [ 8 ].

[ 1 ] Cement, silica fume having a BET specific surface area of 15 to 25 m ² / g, inorganic powder having a 50% cumulative particle size of 0.8 to 5 μm, aggregate A having a maximum particle size of 1.2 mm or less, and a high-performance water reducing agent A cement composition containing an antifoaming agent and water, wherein the cement content is 55 to 65% by volume and the silica fume content is 5 to 5% in a total amount of 100% by volume of the cement, the silica fume and the inorganic powder. 25% by volume, a method for producing a cementitious hardened body made of a cement composition having a proportion of the inorganic powder of 15 to 35% by volume, wherein the cement composition is placed in a mold, A molding step for obtaining an uncured molded body, and after curing the above-mentioned uncured molded body at 10 to 40 ° C. for 24 hours or more for sealing or aerating, the mold is removed from the mold and cured. Normal temperature curing process The cured molded body is subjected to one or both of steam curing or hot water curing at 70 ° C. or more and less than 100 ° C. for 1 hour or more and autoclave curing at 100 to 200 ° C. for 1 hour or more, and after heat curing Heat curing step for obtaining a cured product of the above and the cured product after the heat curing are heated at 150 to 200 ° C. for 24 hours or more (however, excluding heating by autoclave curing) to obtain the cementitious cured product. A method for producing a hardened cementitious body comprising a high-temperature heating step.
[ 2 ] The method for producing a cementitious cured body according to [ 1 ], further including a water absorption step for allowing the cured molded body to absorb water between the room temperature curing step and the heat curing step.
[ 3 ] The method for producing a cementitious cured body according to [ 2 ], wherein the cured molded body is immersed in water in the water absorption step.
[ 4 ] The method for producing a hardened cementitious material according to [ 3 ], wherein in the water absorption step, the cured molded body is immersed in water under reduced pressure.
[5] In the water absorbing process, the molded body above cured, after immersion in boiling water, according to [3] for cooling the temperature remains immersed the molded product 40 ° C. or less A method for producing a cementitious hardened body.
[ 6 ] In the normal temperature curing step, when the cured molded body expresses a compressive strength of ²⁰ to 100 N / mm ² , the cured molded body is demolded from the formwork. [ 1 ] to [ 5 ] A method for producing a hardened cementitious body according to any one of the above.
[7] The cement composition includes one or more fibers selected from the group consisting of metal fibers, organic fibers, and carbon fibers, and the ratio of the fibers in the cement composition is 3% by volume or less. [1] A method for producing a hardened cementitious body according to any one of [6].
[8] The method for producing a hardened cementitious material according to any one of [1] to [7], wherein the ratio of the aggregate A in the cement composition is 20 to 40% by volume.

According to the production method of cementitious cured product of the present invention, even in a cement composition (mortar), it is possible to exhibit high compressive strength after curing (e.g., 350 N / mm ² or higher). Further, according to the method of manufacturing cementitious cured product of the present invention, even in a cement composition comprising a coarse aggregate (concrete), exhibits high compressive strength after curing (e.g., 300N / mm ² or higher) be able to.

The cement composition (hereinafter also referred to as “the cement composition of the present invention” ) used in the method for producing a hardened cementitious material of the present invention is cement, silica fume having a BET specific surface area of 15 to 25 m ² / g (hereinafter referred to as “the cement composition of the present invention”). "Silica fume" may be abbreviated.), 50% cumulative particle size inorganic powder (hereinafter, may be abbreviated as "inorganic powder") 0.8 to 5 μm, and maximum particle size 1.2 mm or less bone A cement composition comprising material A, a high-performance water reducing agent, an antifoaming agent and water, wherein the proportion of cement is 55 to 65% by volume and the proportion of silica fume is 100% by volume of the total amount of cement, silica fume and inorganic powder. 5 to 25% by volume and the proportion of the inorganic powder is 15 to 35% by volume.

Hereafter, the manufacturing method of the cementitious hardened body formed by hardening | curing the cement composition of this invention is demonstrated in detail.
An example of a method for producing a hardened cementitious material of the present invention includes a molding step of placing the above-described cement composition of the present invention in a mold to obtain an uncured molded product, and an uncured molded product, After a sealing curing or aerial curing for 24 hours or more at 10 to 40 ° C., a room temperature curing process for removing the mold from the mold and obtaining a cured molded body, and for the cured molded body, 1 to 70 ° C. or more and less than 100 ° C. A heat curing process for obtaining a cured product after heat curing by performing either or both of steam curing or warm water curing for more than an hour and autoclave curing at 100 to 200 ° C. for one hour or more, and a cured product after heating curing Is heated at 150 to 200 ° C. for 24 hours or more (however, excluding heating by autoclave curing) to include a high-temperature heating step of obtaining a cementitious hardened body.

Claims (18)

Cement, silica fume with a BET specific surface area of 15 to 25 m ² / g, inorganic powder with a 50% cumulative particle size of 0.8 to 5 μm, aggregate A with a maximum particle size of 1.2 mm or less, high-performance water reducing agent, antifoaming A cement composition comprising an agent and water,
In the total amount of 100% by volume of the cement, the silica fume and the inorganic powder, the proportion of the cement is 55 to 65% by volume, the proportion of the silica fume is 5 to 25% by volume, and the proportion of the inorganic powder is 15 to 35% by volume. Cement composition characterized by being.   The cement composition according to claim 1, wherein the cement composition does not contain glass fibers.   The cement composition according to claim 1 or 2, wherein an amount of the water is 10 to 20 parts by mass with respect to 100 parts by mass of the total amount of the cement, the silica fume, and the inorganic powder.   The cement composition according to any one of claims 1 to 3, wherein the inorganic powder is one or more selected from the group consisting of quartz powder, volcanic ash, and fly ash.   The cement composition includes one or more fibers selected from the group consisting of metal fibers, organic fibers, and carbon fibers, and the proportion of the fibers in the cement composition is 3% by volume or less. The cement composition according to any one of the above.   The cement composition according to any one of claims 1 to 5, wherein a ratio of the aggregate A in the cement composition is 20 to 40% by volume.   The cement composition according to any one of claims 1 to 6, wherein the aggregate A has a modified Mohs hardness of 9 or more. The cement composition according to any one of claims 1 to 7, wherein the compressive strength after curing is 400 N / mm ² or more.   The flow value before curing is 200 mm or more as a value measured without performing 15 drop motions in the method described in "JIS R 5201 (Cement physical test method) 11. Flow test". The cement composition according to any one of -8.   The cement composition according to any one of claims 1 to 5, wherein the cement composition includes an aggregate B having a maximum particle size of more than 1.2 mm and 13 mm or less.   The cement composition according to claim 10, wherein the ratio of the total amount of aggregate A and aggregate B in the cement composition is 25 to 40% by volume. The cement composition according to claim 10 or 11, wherein the compressive strength after curing is 300 N / mm ² or more. A method for producing a cementitious hardened body comprising the cement composition according to any one of claims 1 to 12,
A molding step of placing the cement composition in a mold to obtain an uncured molded body,
Room temperature curing step of obtaining the cured molded body by removing the mold from the mold after curing the uncured molded body at 10 to 40 ° C. for 24 hours or more, or curing in the air,
The cured molded body is subjected to either or both of steam curing or hot water curing at 70 ° C. or more and less than 100 ° C. for 1 hour or more and autoclave curing at 100 to 200 ° C. for 1 hour or more, and after the heat curing A heat curing process to obtain a cured product;
A high-temperature heating step of heating the cured body after the heat curing at 150 to 200 ° C. for 24 hours or more (excluding heating by autoclave curing) to obtain the cementitious cured body,
A method for producing a hardened cementitious material, comprising:   The method for producing a cementitious hardened body according to claim 13, further comprising a water absorption step for allowing the cured molded body to absorb water between the room temperature curing step and the heat curing step.   The method for producing a cementitious cured body according to claim 14, wherein the cured molded body is immersed in water in the water absorption step.   The method for producing a hardened cementitious body according to claim 15, wherein in the water absorption step, the cured molded body is immersed in water under reduced pressure.   The cementitious cured product according to claim 15, wherein in the water absorption step, the cured molded body is immersed in boiling water, and then the water temperature is cooled to 40 ° C or lower while the molded body is immersed. Manufacturing method. In the said normal temperature curing process, when the said hardening molded object expresses the compressive strength of 20-100 N / mm < ² >, the said hardening molded object is demolded from the said formwork. The manufacturing method of the cementitious hardened | cured material of description.