JP3150164B2 - 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 and a cement composition which are used mainly in the field of civil engineering and construction and have excellent strength development and dimensional stability.

[0002]

2. Description of the Related Art Conventionally, fiber reinforced mortars in which fibers are mixed with mortar have been widely used for structures and the like because they have superior bending strength, tensile strength, and toughness as compared with ordinary mortars. .

However, the conventional fiber-reinforced mortar has a problem that it must be steam-cured or autoclave-cured in practice because it has a large drying shrinkage and a low initial strength.

On the other hand, the present applicant has proposed a composition comprising granulated blast furnace slag-cement-calcium aluminate-gypsum (Japanese Patent Application Laid-Open No. 58-22365), and has obtained dimensional stability and strength development. Although the invention has been improved, it has been found that the use of a calcium aluminosilicate glass having a specific composition can further improve the dimensional stability and strength development, and have completed the present invention.

[0005]

That is, the present invention provides a blast furnace
It is a cement admixture containing lag or fly ash pozzolanic substance, calcium aluminosilicate glass, and inorganic sulfate as active ingredients, and a cement admixture containing them and fibers as active ingredients. It is a cement composition containing an admixture.

Hereinafter, the present invention will be described in detail.

In the present invention , blast furnace slag or fly ash is used.
To use a pozzolanic material made of.

Here, blast furnace slag is usually used, which is obtained by granulating slag produced from a blast furnace. The components are not particularly limited and can be used if the JIS basicity is about 1.80 or more. is there. The fineness of blast furnace slag is
2,000 cm ² / g or more is preferable in the brane specific surface area, and 3,500
~ 6,000 cm ² / g is more preferred.

[0009] Fly ash is a part of coal ash discharged when pulverized coal is burned in a thermal power plant.
It is a by-product with clinker ash and cinder ash. The chemical composition of fly ash is SiO ₂ 55
65 wt%, a Al ₂ O ₃ 20 to 30 wt%, the other, Fe ₂
Those containing O ₃ , CaO, SO ₃ , MgO and the like can be used. Also, fly ash specified in JIS A 6201 can be used. The fineness of fly ash is preferably one having a Blaine specific surface area of 4,000 cm ² / g or more.

The amount of the pozzolanic substance used is preferably 30 to 80 parts by weight based on 100 parts by weight of the cement and the pozzolanic substance in total. If it is less than 30 parts by weight, it is not preferable from the viewpoint of dimensional stability, and if it exceeds 80 parts by weight, it is not preferable from the viewpoint of developing strength.

The calcium aluminosilicate glass (hereinafter referred to as CAS glass) according to the present invention has a composition range of C
aO30~60 wt%, Al ₂ O ₃ 20 to 60 wt%, and SiO ₂ 5 to 25
Preferably wt%, CaO30～55 wt%, Al ₂ O ₃ 30 to 60 wt%, and SiO ₂ 10 to 20 wt% is more preferable. When CaO is less than 30% by weight or Al ₂ O ₃ exceeds 60% by weight, rapid hardening tends to be inferior. Conversely, CaO exceeds 60% by weight or Al ₂ O ₃ is less than 20% by weight. However, even if a large amount of the setting modifier is added, instantaneous setting occurs, which is not preferable from the viewpoint of workability. If the content of SiO ₂ is less than 5% by weight, long-term elongation of strength cannot be expected, and if it exceeds 25% by weight, the initial strength tends to be small.

Incidentally, general industrial raw materials include MgO, Fe ₂ O ₃ ,
Naturally, impurities such as TiO ₂ , K ₂ O, and Na ₂ O are included.
Since these impurities extend the vitrified region of the CaO-Al ₂ O ₃ -SiO ₂ system, the presence of up to less than 10% by weight is preferable, and rapid hardening, workability, elongation of long-term strength, etc. There is no problem in various properties. Also, when producing CAS glass,
It is preferable to add an alkali nitrate such as NaNO ₃ or KNO ₃ which is a general glass flux, calcium fluoride, borax, or the like, since the melting point of the glass is lowered.

The glass referred to in the present invention is "a glass exhibiting a glass transition point" determined from thermal analysis. It is not necessary that all of them are glassy, and the vitrification ratio is preferably 50% by weight or more, more preferably 70% by weight or more, and most preferably 80% by weight or more. At less than 50% by weight,
The initial strength tends to decrease. Incidentally, the vitrification rate, for example, in the present invention, CAS glass, 1,000 ℃
For 2 hours, and then slowly cooled at a cooling rate of 5 ° C./min. The area S ₀ of the main peak of the crystalline mineral determined by the powder X-ray diffraction method and the area of the main peak of the crystal in the CAS glass were determined. It was calculated from the area S according to Equation 1.

[0014]

(Equation 1)

The CAS glass has, for example, an average chemical composition of 40 to 43% by weight of CaO, 5 to 8% by weight of MgO, and 13 to 15% of Al ₂ O _3.
It is completely different from the composition of granulated blast furnace slag by-produced in metallurgy or metal smelting which is 31% to 35% by weight of SiO _{2 and} 31 to 35% by weight of SiO ₂ . Further, CAS glass is completely different from the composition of alumina cement. That is, the SiO ₂ content of ordinary alumina cement is less than 5% by weight [Junichi Kasai, Concrete Engineering, Vol. 22, No. 8, page 67 (1984)], and the vitrification ratio exceeds 25%. Nothing [Academic Press, Inc., London, 1964, published by HFWTaylor, The Chemistry of Cement, No. 2]
Vol. 16, page 16].

The raw materials for producing CAS glass according to the present invention include CaO raw materials, Al ₂ O ₃ raw materials, and SiO ₂ raw materials. The CaO-containing material, quick lime, slaked lime, and limestone etc., As the Al ₂ O ₃ feedstocks, alumina, bauxite, diaspore, feldspar, and clay or the like, and further, as the SiO ₂ feedstocks, Kay Sand, clay and diatomaceous earth can be used. It is also possible to supplement a relatively inexpensive blast furnace slag with a CaO-based raw material and an Al ₂ O ₃ -based raw material.
The CAS glass according to the present invention is obtained by blending the above CaO-based raw material, Al ₂ O ₃ -based raw material, and SiO ₂ -based raw material at a predetermined ratio, and melting them using a direct-current-type melting furnace or a high-frequency furnace. A method of blowing the melt with compressed air or high-pressure water, or
Manufactured by pouring into water. Moreover,
It can also be manufactured by melting in a rotary kiln and quenching. The finer the fineness of the CAS glass, the better the reactivity as it is better.
The specific surface area of the brane is preferably 3,000 cm ² / g or more.

The inorganic sulfate according to the present invention is a sulfate of an alkali metal or an alkaline earth metal. Of these, anhydrous, hemihydrate and dihydrate calcium sulfate are preferred, and type II anhydrous gypsum is particularly preferred. The fineness of the inorganic sulfate is preferably 3,000 cm ² / g or more in terms of Blaine specific surface area.
The amount of inorganic sulfate used is based on 100 parts by weight of CAS glass.
It is preferably 50 to 300 parts by weight, more preferably 100 to 200 parts by weight. Less than 50 parts by weight is not preferable in terms of strength development,
If it exceeds 300 parts by weight, it is not preferable from the viewpoint of dimensional stability.

In the present invention, CAS glass and inorganic sulfate are used as a hard material. The amount of the rapidly hardened material is preferably 10 to 30 parts by weight, more preferably 15 to 25 parts by weight, based on 100 parts by weight of the total of the pozzolanic substance and the cement. When the amount is less than 10 parts by weight, the effect of increasing the initial strength is small.

Here, the cement according to the present invention includes:
Various Portland cements and various mixed cements mixed with blast furnace slag, fly ash or silica,
Further, special cements such as moderate heat cement, white cement, and colloid cement can be used.

In the present invention, when the hardened material is mixed with the pozzolanic substance and the cement, the setting may start in a very short time. In such a case, the setting control having the action of retarding the setting of the cement may be performed. It is preferred to use agents. Here, as the setting regulator, citric acid, tartaric acid,
Organic acids such as gluconic acid, succinic acid, and maleic acid, or salts thereof, and mixtures thereof with alkali carbonates such as sodium carbonate and potassium carbonate can be used. The amount of the setting regulator used is usually preferably 2 parts by weight or less based on 100 parts by weight of the total of the pozzolanic substance and the cement.

It is also possible to use a commercially available water reducing agent,
A considerable effect can be obtained.

Further, in the present invention, it is also possible to use other admixtures commonly used for mortar and concrete. Other admixtures include, for example, aggregates, polymer emulsions and latexes, water repellents such as silicone resins, coloring agents, AE agents, AE water reducing agents, fluidizers,
Rust inhibitors, water retention agents such as methylcellulose, waterproofing agents such as calcium chloride and sodium silicate, foaming agents, foaming agents, calcium salts such as calcium hydroxide, and antifreezing agents. More than one species can be used together in amounts that do not substantially inhibit the purpose of the present invention.

The fibers according to the present invention include carbon fibers, glass fibers, alkali-resistant glass fibers, inorganic fibers such as alumina fibers, boron fibers and asbestos, polypropylene fibers, nylon fibers, acrylic fibers, polyethylene fibers, vinylon fibers, and the like. Organic fibers such as aramid fibers and polyacetal fibers; and metal fibers such as steel fibers. These fibers are used for various purposes depending on the properties of the fibers, such as fiber length, fiber diameter, density, Young's modulus, tensile strength, and aspect ratio, but can be used in any case. The amount of the fiber used is usually preferably 0.05 to 10 parts by volume with respect to 100 parts by volume of the cement composition, but is not particularly limited thereto.

The apparatus for mixing the cement admixture and the cement composition of the present invention is not particularly limited. Any existing stirring device such as a Nauter mixer can be used.

The method of mixing each material is not particularly limited, and each material may be mixed at the time of construction.
It is also possible to mix some or all of them in advance. Further, as a method of producing the mortar of the present invention, a method of simultaneously spraying mortar from a mortar spray gun and fibers with a compressed gas from a chopper gun, or mixing mortar and fibers in a mixer and forming a mold in a mold Any method such as a filling method may be used, and the forming method is not limited.

The mortar using the cement composition of the present invention exhibits strength required for demolding in a short time, and is excellent in durability and dimensional stability. The strength of the product of the present invention is
It is adjusted by the ratio of CAS glass and inorganic sulfate, or the amount of quenched hard material consisting of CAS glass and inorganic sulfate used in pozzolanic substances and cement.

Further, by heating with hot air, steam, or the like, the strength required for demolding can be obtained in a shorter time.

[0028]

The present invention will be described in more detail below.

Example 1 A commercially available special grade reagent, CaCO ₃ , Al ₂ O ₃ , and SiO _2, was mixed, and 300 g of the mixture was placed in a carbon crucible.
After being heated and melted at 0 ° C., it was immersed in water and quenched to synthesize 14 types of CAS glasses A to N shown in Table 1. A,
Since B, H, J, K, and N are not in the vitrification region of the CaO-Al ₂ O ₃ -SiO ₂ system, 1% by weight of CaF ₂ is added and melted, and quenched. Vitrified. These CAs
Each of the S glasses was pulverized to a specific surface area of 4,000 cm ² / g. The analysis results are also shown in Table 1.

[0030]

[Table 1]

Next, 40 parts by weight of cement, pozzolanic substance α
60 parts by weight, inorganic sulfate 15 parts by weight, and aggregate 80 parts by weight,
A mortar was prepared by mixing a CAS glass having the composition shown in Table 2 with a fiber, and the compressive strength and dimensional stability were measured. The size of the specimen was 4 × 4 × 16 cm, the ratio of water / (cement + pozzolan) was 40%, and the curing conditions were 20 ° C. and 65% RH. Note that a Nauter mixer was used for mixing the respective materials. The results are also shown in Table 2.

<Materials> Cement: Ordinary Portland cement made by Denki Kagaku Kogyo Co., Ltd. Pozzolanic substance α: Blast furnace slag, made by Nippon Steel Corporation, Brain 3,
800 cm ² / g CAS glass: Table 1 Inorganic sulfate: Type II anhydrous gypsum, Blaine specific surface area 5,90
0cm ² / g Fiber a: Carbon fiber, trade name “Kureka Chop C-103 T” manufactured by Kureha Chemical Industry Aggregate: Silica sand No. 7

<Measurement method> Compressive strength: Measured according to JIS R 5201. Curing conditions were as follows: 20 ° C., 65% RH Dimensional stability: Shrinkage rate, base length measurement 24 hours after molding, according to JIS A 1129, measured by dial gauge method.

[0034]

[Table 2]

Example 2 The procedure of Example 1 was repeated, except that 10 parts by weight of CAS glass was used and the pozzolanic substance and the type of fiber were changed as shown in Table 3. The results are also shown in Table 3.

<Materials used> Pozzolanic substance β: fly ash, manufactured by Joban Thermal Power Co., Ltd.
Brain 4,600cm ² / g 〃 γ: Silica fume, fiber manufactured by Nippon Kaika Co., Ltd. b: Polypropylene fiber, trade name “TAFLIGHT” manufactured by Nippon Teikoku Sangyo Co., Ltd. 〃 c: Vinylon fiber, trade name “Kuraray RKW manufactured by Kuraray Co., Ltd.”
182 × 6 ”diameter 14μ specific gravity 1.3 ｄ d: aramid fiber, product name“ Kepler ”manufactured by DuPont 〃 e: acrylic fiber, product name“ Dranit 10 ”manufactured by Hoechst

[0037]

[Table 3]

Example 3 The procedure of Example 1 was repeated, except that 10 parts by weight of CAS glass E was used and the amounts of cement and pozzolanic substance were changed as shown in Table 4. The results are shown in Table 4.

[0039]

[Table 4]

Example 4 As shown in Table 5, the procedure was performed in the same manner as in Example 1 except that the amounts of the CAS glass and the inorganic sulfate were changed. Table 5 shows the results
It is described together.

[0041]

[Table 5]

[0042]

By using the cement admixture of the present invention, a cement composition having good strength development and good dimensional stability after curing can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C04B 22/14 C04B 22/14 B 28/02 28/02 // C04B 103: 14 (56) References JP-A-4-164845 (JP, A) JP-A-4-97932 (JP, A) JP-A-2-153850 (JP, A) JP-A-4-55351 (JP, A) JP-A-4-80290 (JP, A) Kaihei 4-175397 (JP, A) JP-B-57-13511 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 22/08 C04B 14/38 C04B 16/06 C04B 18/08 C04B 18/14 C04B 22/14 C04B 28/02

Claims (3)

(57) [Claims] 1. A cement admixture comprising a pozzolanic substance comprising blast furnace slag or fly ash , calcium aluminosilicate glass, and an inorganic sulfate as active ingredients. 2. A cement admixture comprising a blast furnace slag or fly ash, a pozzolanic substance, calcium aluminosilicate glass, an inorganic sulfate, and fibers as active ingredients. 3. A cement according to claim 1 or cement composition comprising a cement admixture of 2 described.