Rapid-hardening cement composition

1. A rapid-hardening cement composition, comprising:

a rapid-hardening admixture; and

a cement in an amount of 100 to 2,000 parts by mass with respect to 100 parts by mass of the rapid-hardening admixture,

wherein the rapid-hardening admixture comprises: a calcium aluminate; an anhydrite in an amount of 50 to 200 parts by mass with respect to 100 parts by mass of the calcium aluminate; and a first setting modifier in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the calcium aluminate, and

wherein an average particle diameter of the calcium aluminate is in a range of 8 to 100 μm, and an average particle diameter of the first setting modifier is in a range of 5 μm or less.

2. The composition of claim 1 , wherein the first setting modifier comprises a compound selected from the group consisting of an inorganic carbonate, an oxycarboxylic acid, a sodium aluminate, and a sodium sulfate.

3. The composition of claim 1 , further comprising:

a second setting modifier, added such that a total amount of the first and second setting modifier with respect to an entire amount of the rapid-hardening cement composition is in a range of 0.01% to 5% by mass.

4. The composition of claim 3 , wherein the second setting modifier, as added, is a setting modifier-comprising mixture comprising:

(i) an inorganic powder and

(ii) the second setting modifier in an amount of 50 to 300 parts by mass with respect to 100 parts by mass of the inorganic powder,

wherein the inorganic powder is one or more selected from the group consisting of a cement, a limestone powder, a silica stone powder, a blast furnace slag powder, a coal ash, a fly ash, a clay mineral, and a calcium aluminate powder, and

wherein the second setting modifier comprises a compound selected from the group consisting of an inorganic carbonate, an oxycarboxylic acid, a sodium aluminate, and a sodium sulfate.

5. The composition of claim 1 , further comprising:

short fibers that consist of organic short fibers and/or carbon short fibers are further included in an amount of 0.1% to 0.3% by mass with respect to an entire amount of the rapid-hardening cement composition.

6. The composition of claim 1 , further comprising:

a viscosity agent in an amount of 0.1% to 1% by mass with respect to an entire amount of the rapid-hardening cement composition.

7. The composition of claim 1 , further comprising:

a powdered emulsion in an amount of 0.5% to 30% by mass with respect to an entire amount of the rapid-hardening cement composition.

8. The composition of claim 1 , further comprising:

an inorganic filler that consists of one or more selected from the group consisting of a silica stone fine powder, a limestone fine powder, a coal ash fine powder, a fly ash, a montmorillonite fine powder, a feldspar fine powder, and a blast furnace slag fine powder, in an amount of 4% to 50% by mass with respect to an entire amount of the rapid-hardening cement composition.

9. The composition of claim 1 , further comprising:

an anti-freezing agent that consists of one or more selected from the group consisting of a sodium acetate, a calcium acetate, and a calcium nitrite, in an amount of 1% to 10% by mass with respect to an entire amount of the rapid-hardening cement composition.

10. The composition of claim 1 , further comprising:

organic fibers and/or carbon fibers in an amount of 0.1% to 0.3% by mass with respect to an entire amount of the rapid-hardening cement composition.

11. The composition of claim 1 , further comprising:

an inorganic filler comprising silica stone fine powder, a limestone fine powder, a coal ash fine powder, a fly ash, a montmorillonite fine powder, a feldspar fine powder, and/or a blast furnace slag fine powder, in an amount of 4% to 50% by mass with respect to an entire amount of the rapid-hardening cement composition.

12. The composition of claim 1 , further comprising:

an anti-freezing agent comprising a sodium acetate, a calcium acetate, a calcium nitrite, or a mixture of two or more of any of these, in an amount of 1% to 10% by mass with respect to an entire amount of the rapid-hardening cement composition.

13. The composition of claim 1 , wherein the first setting modifier comprises an inorganic carbonate, an oxycarboxylic acid, a sodium aluminate, a sodium sulfate, or a mixture of two or more of any of these.

14. The composition of claim 3 , wherein the second setting modifier, as added, is a setting modifier-comprising mixture comprising:

(i) an inorganic powder and

(ii) the second setting modifier in an amount of 50 to 300 parts by mass with respect to 100 parts by mass of the inorganic powder,

wherein the inorganic powder comprises a cement, limestone powder, silica stone powder, blast furnace slag powder, coal ash, fly ash, clay mineral, calcium aluminate powder, or a mixture of two or more of any of these, and

wherein the second setting modifier comprises an inorganic carbonate, oxycarboxylic acid, sodium aluminate, or sodium sulfate.

15. The composition of claim 1 , wherein the anhydrite comprises a type II anhydrite.

16. The composition of claim 1 , wherein the calcium aluminate has a vitrification rate of 80% or more.

17. The composition of claim 1 , wherein the calcium aluminate has a Blaine specific surface area in a range of from 3,000 to 5,500 cm 2 /g.

18. The composition of claim 5 , wherein the short fibers have a fiber length in a range of 1 mm to 10 mm.

19. The composition of claim 1 , wherein the first setting modifier comprises an inorganic carbonate.

20. An injection grout, comprising the composition of claim 1 .