JP3219161B2 - Cement admixture and cement composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture mainly used in the field of civil engineering and construction and a cement composition using the same.

[0002] In the present invention, concrete is
It is a general term for cement paste, mortar, and concrete.

[0003]

2. Description of the Related Art It has been known that calcium aluminate, gypsum, a setting modifier and the like are mixed with Portland cement to form a rapidly hardening cement. In order to show rapid hardening, it became usable several hours after casting. However, in some applications, the initial strength may not satisfy the required strength (Japanese Patent Application Laid-Open Nos. 3-75249 and 2-234550).

In view of the current situation, the present inventors have studied cement admixtures having excellent initial strength and found that the use of a cement admixture of a specific component can solve the problems of the conventional technique. As a result, the present invention has been completed.

[0005]

That is, the present invention relates to an amorphous material.
A cement admixture comprising calcium aluminates, inorganic sulfates, and calcium carbonate having a particle size of at least 2,000 cm ² / g Blaine specific surface area, and a cement composition comprising cement and the cement admixture It is.

Hereinafter, the present invention will be described in detail.

[0007] Calcium aluminates according to the present invention
The (hereinafter referred CA acids), usually by an electric furnace or a rotary kiln, means a calcium aluminate mineral to produce a high temperature, those of crystalline, amorphous ones there
However, in the present invention, an amorphous material is used. It should be noted that the presence of other components and impurities in the production process is not particularly limited.

As the crystalline calcium aluminate mineral, if CaO is C and Al ₂ O ₃ is A, CA, C _{5 A} 3, C ₁₂ A ₇ ,
And those shown as C ₃ A, and the like, as well, when the Fe ₂ O ₃ F, the X and halogen, as crystalline other components are present in the _{crystal, C 11 A 7 · CaX 2} , C 3 A 3 · CaX _2, C ₄ AF, and C ₃ A ₃ · CaSO ₄
Etc. can be mentioned, et al are those shown and so on.

A typical example of an amorphous calcium aluminate mineral is the same as a crystalline one in terms of composition, but it has been made amorphous by rapid cooling. Can not be specified.

From the viewpoint of reactivity, amorphous ones are preferable to crystalline ones, and from the viewpoint of composition, those having a C content of 30 to 60% by weight in calcium aluminate are preferable. More preferably, it is about 52% by weight.

[0011] The fineness of the CAs is determined by a Blaine specific surface area of 2,000.
About 0 to 8,000 cm ² / g is preferable.

The inorganic sulfate according to the present invention is a sulfate of an alkali metal or an alkaline earth metal, and among them, anhydrous, hemihydrate or dihydrate calcium sulfate is preferable.
The use of type II anhydrous gypsum is particularly preferred in terms of strength development.

The type II anhydrous gypsum indicates the type of type II CaSO _{4 in} the X-ray diffraction pattern, and is not limited by impurities contained industrially.

The fineness of the inorganic sulfate is preferably about 2,000 to 8,000 cm ² / g in terms of Blaine specific surface area.

The amount of the inorganic sulfate to be used is preferably 50 to 500 parts by weight, particularly preferably 100 to 300 parts by weight, based on 100 parts by weight of CAs. If the amount is less than 50 parts by weight, the strength development is insufficient, and if it exceeds 500 parts by weight, the stability of concrete may be deteriorated.

The calcium carbonate according to the present invention is not particularly limited, but preferably has a CaCO ₃ content of 60% by weight or more, more preferably 80% by weight or more.

As calcium carbonate, chemically purified reagents or lime carbonate can be used. For example, limestone produced naturally, such as from Akiyoshidai or Chichibu, is ground and used. It is also possible.

The fineness of the calcium carbonate is preferably 2,000 cm ² / g or more in terms of Blaine specific surface area, and 4,000 to 8,000 cm ² / g
Is more preferred. If the Blaine specific surface area is less than 2,000 cm ² / g, the reactivity is poor and the initial strength may not be expected.

The amount of calcium carbonate used is preferably 1 to 200 parts by weight, more preferably 10 to 50 parts by weight, based on 100 parts by weight of CAs. If the amount is less than 1 part by weight or exceeds 200 parts by weight, the effect of improving the initial strength, which is the object of the present invention, may not be obtained.

In the present invention, a cement admixture containing CAs, an inorganic sulfate, and a specific calcium carbonate is used. The amount of the cement admixture used is a total of 100% by weight of cement and cement admixture. 5 to 50 parts by weight, more preferably 10 to 25 parts by weight, per part. If it is less than 5 parts by weight, rapid hardening is inferior, and if it exceeds 50 parts by weight, workability may be poor.

The cement according to the present invention is not particularly limited, and various portland cements which are usually used, such as ordinary / early high / super early / moderate heat, and blast furnace slag, fly, etc. Various mixed cements obtained by mixing ash or silica, and special cements such as expanded cement obtained by mixing an expander with Portland cement, alumina cement, and colloid cement are also included.

In the present invention, it is also possible to use other various admixtures in combination.

Other admixtures include, for example, aggregates such as silica sand, natural sand, and gravel; setting modifiers such as organic acids, alkali carbonates, and saccharides; glass fibers, carbon fibers, and steel fibers. Fiber, polymer emulsion and latex, colorant, AE agent, water reducing agent, AE water reducing agent, fluidizer,
Rust inhibitors, insoluble additives in water such as methyl cellulose,
Thickeners, water retention agents, waterproofing agents such as calcium chloride and sodium silicate, foaming agents, foaming agents, calcium salts such as calcium hydroxide, and antifreezing agents and the like, and one or more of them Can be used together within a range that does not substantially inhibit the object of the present invention.

The method of mixing each material in the present invention is not particularly limited, and each material may be mixed at the time of construction, or a part or all of them may be mixed in advance.

The apparatus for mixing the cement admixture and the cement composition of the present invention is not particularly limited. Examples thereof include a tilting mixer, an omni mixer manufactured by Chiyoda Giken Kogyo, a V-type mixer, a Henschel mixer, Any existing agitating device such as a Nauta mixer can be used.

[0026]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

Example 1 CAs, inorganic sulfates, and calcium carbonate were mixed using the composition shown in Table 1 to obtain a cement admixture, and bone was added to cement and 100 parts by weight of the cement admixture in total. Lumber 2
The mortar was adjusted with 00 parts by weight and 40 parts by weight of water, and a predetermined compressive strength was measured by the following measuring method. The results are also shown in Table 1.

<Measurement method> Compressive strength: Measured in accordance with JIS R 5201. Curing conditions were 20 ° C, 80% up to 1 day of age, and water curing at 20 ° C after 1 day.

<Materials Used> Cement: Ordinary Portland cement manufactured by Denki Kagaku Kogyo Co. CA A: Calcium aluminate with CaO content of 48% by weight, amorphous, Blaine specific surface area 5,800 cm ² / g B: Calcium fluoroaluminate , Amorphous, CaO / Al ₂ O
₃ / CaF ₂ molar ratio 1 / 0.8 / 0.2, Blaine specific surface area 5,300 cm ² /
g C: calcium aluminosilicate glass, amorphous, CaO / Al
₂ O ₃ / SiO ₂ weight ratio 45/45/10, Blaine specific surface area 5,500 cm ²
/ g inorganic sulfate: Type II anhydrous gypsum, Blaine specific surface area 6,50
0cm ² / g Calcium carbonate a: Natural limestone powder from Chichibu, Blaine specific surface area 6,200cm ² / g Calcium carbonate b: Natural limestone powder from Chichibu, Blaine specific surface area 2,300cm ² / g Calcium carbonate c: Natural limestone powder from Chichibu, Brain specific surface area 1,120cm ² / g Aggregate: Niigata prefecture Himekawa river sand, specific gravity 2.6, FM2.62

[0030]

[Table 1]

[0031]

According to the present invention, concrete having excellent initial strength can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 22/08 C04B 22/10 C04B 22/14

Claims (2)

(57) [Claims] 1. A cement admixture comprising an amorphous calcium aluminate, an inorganic sulfate, and calcium carbonate having a particle size of at least 2,000 cm ² / g. 2. A cement composition comprising a cement and the cement admixture according to claim 1.