JPH10265248A - Cement admixture and cement composition using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement admixture excellent in initial setting and in which deterioration of a cement composition due to an influence of an alkali-aggregate reaction is small, and a cement composition using the same. SOLUTION: A cement admixture containing aluminum sulfite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cement admixture,
In particular, it relates to a cement quick setting agent.

[0002]

2. Description of the Related Art Conventionally, a cement quick-setting agent used in a spraying method rapidly undergoes a hydration reaction when mixed with cement, and hardens within a few seconds to a few tens of seconds. As a component of such a cement quick setting agent, a mixture of calcium aluminate and alkali metal aluminate or alkali metal carbonate was mainly used (Japanese Patent Publication No. 56-2).
No. 7457).

[0003]

However, alkali metal aluminates and alkali metal carbonates are components that promote the alkali-aggregate reaction, and when alkali-reactive aggregate is used as concrete aggregate, With these alkali metal aluminates and alkali metal carbonates,
There has been a problem that cracks may be formed due to generation of a reaction product generated by a chemical reaction with the alkali-reactive aggregate and expansion due to water absorption, and the durability of concrete may be lost. Therefore, as a component of the cement quick-setting agent, a cement quick-setting agent that does not contain or is reduced in a component that promotes an alkali-aggregate reaction has been required.
As a result of various studies, the present inventor has obtained a finding that the above problem can be solved by adding a specific component, and has completed the present invention.

[0004]

That is, the present invention relates to a cement admixture characterized by containing aluminum sulfite, and a cement composition characterized by using the cement admixture. Things.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

[0006] As the cement of the present invention, various portland cements, such as ordinary, early-strength, moderate heat, and ultra-high-strength, which are commercially available, and various mixed cements obtained by mixing fly ash, blast furnace slag, etc. with these portland cements are used. And fluorocement containing fluorocalcium aluminate. These may be finely powdered and used. Of these, ordinary Portland cement is preferred in terms of good pumpability after kneading the cement composition. In the case where the early-strength Portland cement is used, the slump is greatly reduced, and the pumpability after kneading the cement composition may be reduced.

[0007] The cement admixture of the present invention (hereinafter referred to as the present admixture) does not contain or has reduced content of components such as sodium and potassium which promote the alkali-aggregate reaction.

[0008] The aluminum sulfite used in the present invention is a component which causes an initial setting when mixed with cement, and has an effect of suppressing the alkali-aggregate reaction even if it contains a component which promotes the alkali-aggregate reaction. It is something with. The aluminum sulfite may anhydride or _{hydrate, Al 2 (SO 3) 3} , Al 2 O 3 · SO 2 · 4H 2
_{O, 4Al 2 O 3 · 3SO} 2 · 18H 2 O, 5Al 2 O
₃ · 3SO ₂ · 15H ₂ O and the like, can be used one or two or more of these. Among these, Al ₂ (SO ₃ ) ₃ and Al ₂ O ₃ · SO ₂ · 4
H ₂ O is preferred. The particle size of aluminum sulfite is not particularly limited, but is preferably 0.2 mm or less. If it exceeds 0.2 mm, the initial setting may decrease.

The amount of aluminum sulfite used is preferably 2 to 20 parts by weight, and more preferably 5 to 20 parts by weight based on 100 parts by weight of cement.
-15 parts by weight is more preferred. If the amount is less than 2 parts by weight, it is difficult to promote the setting of the cement. If the amount exceeds 20 parts by weight, the long-term strength development may be impaired.

Although aluminum sulfite may be used alone, it is preferable to use it together with various admixtures from the viewpoint of imparting various performances. Although there is no particular limitation on the admixture, calcium aluminate, gypsum, pozzolanic substances, alkali metal aluminates, alkali metal carbonates, and sulfates, hydroxides, and silicates are preferred. Among these, calcium aluminate and alkali metal aluminate are more preferable in terms of initial and long-term strength development, and it is most preferable to use calcium aluminate and alkali metal aluminate in combination.

Calcium aluminate refers to a material obtained by subjecting a mixture of a CaO raw material, an Al ₂ O ₃ raw material and the like to a heat treatment such as firing in a kiln or melting in an electric furnace. Is a quick-setting component that causes the cement composition to set and promotes the development of strength. As mineral components of calcium aluminate, CaO is C and Al ₂ O ₃ is A
In this case, there are crushed calcium aluminate heat-treated products represented by C ₃ A, C ₁₂ A ₇ , CA, CA _{2 and the} like, and one or more of these may be used in combination. In addition, sodium,
Calcium aluminate in which alkali metals such as potassium and lithium are partially dissolved can be used. Among these, amorphous calcium aluminate obtained by quenching a heat-treated product corresponding to the C ₁₂ A ₇ composition is preferable in terms of reaction activity. Calcium aluminosilicate containing SiO ₂ , C ₁₁ A ₇ .CaX ₂ (X is a halogen such as fluorine) in which one CaO of C ₁₂ A ₇ is replaced by a halide such as CaF ₂ , and SO ₃ component C ₄ A ₃ .SO ₃ containing can be used in the same manner as calcium aluminate. Furthermore, alumina cement can be used as well. The particle size of the calcium aluminate, in terms of quick-setting property and the initial strength development, preferably 3000 cm ² / g or more in Blaine value, 4000 cm ² /
g or more is more preferable. If it is less than 3000 cm ² / g, the quick setting property and the initial strength development property may be reduced.

Gypsum is used to improve long-term strength development. Examples of gypsum include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum,
One or two or more of these may be used in combination. Among these, anhydrous gypsum is preferable in terms of strength development.
The particle size of the gypsum is generally good for use in cement, and preferably has a Blaine value of 3000 cm ² / g or more.
From the viewpoint of strength development, it is more preferably 4000 cm ² / g or more.

The pozzolanic substance is intended to improve long-term strength development and suppress expansion due to alkali-aggregate reaction.
Pozzolanic substances include fly ash, blast furnace slag,
Examples thereof include silica fume and kaolin, and one or more of these may be used in combination. Among these,
Use of blast furnace slag or silica fume is preferred in terms of strength development.

The alkali metal aluminate promotes the initial setting of cement. Examples of the alkali metal aluminate include lithium aluminate, sodium aluminate, and potassium aluminate. More than one species may be used in combination. Of these, sodium aluminate is preferred in terms of initial coagulation.

The alkali metal carbonates promote the initial setting of the cement. Examples of the alkali metal carbonates include lithium carbonate, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate and the like. May be used alone or in combination of two or more. Of these, sodium carbonate is preferred in terms of initial setting.

Sulfates promote initial setting of cement and exclude aluminum sulfite. The sulfates include lithium sulfate, sodium sulfate, potassium sulfate, aluminum sulfate, magnesium sulfate, sodium sulfite, and potassium sulfite. Examples thereof include calcium sulfite, sodium hydrogen sulfite, and potassium hydrogen sulfite, and one or more of these may be used in combination. Among these, aluminum sulfate is preferred because it has a large effect of suppressing the alkali-aggregate reaction.

The hydroxide promotes the initial setting of the cement. Examples of the hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, and calcium hydroxide. More than one species may be used in combination. Of these, calcium hydroxide is preferred from the viewpoint of initial setting.

The silicate promotes the initial setting of the cement. Examples of the silicate include lithium silicate, sodium silicate, potassium silicate and magnesium silicate. Two or more kinds may be used in combination. Among these, sodium silicate is preferably used from the viewpoint of initial coagulation.

These various admixtures may be used alone or in combination of two or more with aluminum sulfite. Among these, aluminum sulfite and calcium aluminate and / or alkali metal aluminate are preferred in terms of initial and long-term strength development, and those using aluminum sulfite and calcium aluminate are more preferred. Preferably, a combination of aluminum sulfite, calcium aluminate and alkali metal aluminate is most preferred. Then, one or two of gypsum, pozzolanic substances, alkali metal carbonates, sulfates, hydroxides, and silicates, in addition to those in which aluminum sulfite, calcium aluminate, and alkali metal aluminate are used in combination. It is preferable to use the above various admixtures in combination. Among these substances, gypsum is preferred from the viewpoint of improving strength development.

The amount of the various admixtures used in combination with aluminum sulfite is preferably 20 to 2,000 parts by weight, and more preferably 100 to 1 part by weight based on 100 parts by weight of aluminum sulfite.
000 parts by weight are more preferred. If the amount is less than 20 parts by weight, there is no effect. If the amount exceeds 2,000 parts by weight, the long-term strength development may be impaired.

In addition to the combination of aluminum sulfite, calcium aluminate, and alkali metal aluminate, gypsum, pozzolan substances, alkali metal carbonates, sulfates, hydroxides and silicates, When two or more kinds of various admixtures are used in combination, the amount of these various admixtures used is 100% of aluminum sulfite.
20 to 200 parts by weight, preferably 50 parts by weight,
~ 150 parts by weight is more preferred. If the amount is less than 20 parts by weight, there is no effect, and if it exceeds 200 parts by weight, the long-term strength development may be impaired.

However, when using alkali metal aluminates, alkali metal carbonates, sulfates, hydroxides, and silicates containing sodium and potassium, the amount of these used is determined by the alkali-aggregate reaction. It is preferable to mix an amount that cannot be obtained. For this reason, the amount used is preferably 2 parts by weight or less based on 100 parts by weight of cement.
If it exceeds 2 parts by weight, the alkali-aggregate reaction may be accelerated.

The amount of the admixture is preferably 2 to 20 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of cement. If the amount is less than 2 parts by weight, it is difficult to promote the initial setting of the cement, and if it exceeds 20 parts by weight, the strength development may be impaired.

The aggregate such as fine aggregate and coarse aggregate of the present invention preferably has low water absorption and high aggregate strength, but is not particularly limited. The coarse aggregate includes river gravel, mountain gravel, lime gravel, and the like. As fine aggregate,
River sand, mountain sand, lime sand, silica sand, and the like. The water / cement ratio is preferably 35-65%, more preferably 40-60%. If it is less than 35%, the cement composition cannot be sufficiently mixed, and if it exceeds 65%, strength developability is small, and the amount of the present admixture may be increased.

The present admixture is preferably used in a spraying method as a cement quick setting agent. The spraying method of the present admixture when used as a spraying method is, for example, pneumatically feeding wet cement concrete kneaded with water in advance and merging and mixing the admixture from one of the Y-tubes provided in the middle. Wet spraying method, or cement concrete without water added, dry air spraying method, in which a cement quick-setting agent is added to this and air-pressure fed, and water is combined and mixed from one of the Y-shaped pipes and sprayed. Can also be performed. Among them, the wet spraying method is preferable because the amount of generated dust is small. In the present invention, in order to increase the strength, gypsum may be added to the cement concrete side and used as shotcrete. In the present admixture of the present invention, a water reducing agent, an AE agent, a setting retarder, a fiber and the like may be used in combination. The admixture of the present invention is preferably sealed and stored with an inert gas such as a nitrogen gas in order to avoid contact with air as much as possible from the viewpoint of storage stability.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description will be given based on embodiments.

Example 1 Proctor penetration resistance test and compression strength measurement were carried out using the cement quick-setting agent composed of aluminum sulfite in the amount shown in Table 1 with respect to 100 parts by weight of cement. The test conditions were as follows: water / cement ratio = 60%, cement / sand ratio = 1 /
3 (weight ratio) and the material temperature was 20 ° C. Table 1 shows the results
Shown in (Material used) Cement: Commercial ordinary Portland cement, specific gravity 3.
16 Aluminum sulfite: Main component 4Al ₂ O ₃ .3SO ₂
・ 18H ₂ O, particle size: 0.2 mm Aluminum sulfite: main component Al ₂ (SO ₃ ) ₃ , particle size: 0.2 mm Sand: River sand from Itoigawa City, Niigata Prefecture Specific gravity 2.65 Water: tap water (20 ° C.) (measurement method) Proctor penetration resistance value: 5 quick-setting mortars obtained by mixing and kneading (mixed with a quick-setting agent and mixed for 10 seconds)
cm × 20 cm × 20 cm form quickly packed, 45, 60, 120, 300, 6 from the time when the quick setting agent was added
After 00 seconds, the resistance to penetration of the proctor was measured. Compressive strength: 4 cm x 4 cm of quick-setting mortar obtained by mixing and kneading (mixed with a quick-setting agent and mixed for 10 seconds)
The mold was quickly packed in a × 16 cm form while applying vibration with a vibrator, and the compressive strength was measured with a 20-t pressure resistant machine at a predetermined age.

[0028]

[Table 1]

Example 2 100 parts by weight of aluminum sulfite and the amount shown in Table 2
100% by weight of cement quick-setting admixture made of admixture
Example 1 except that 10 parts by weight was used.
Performed similarly. Table 2 shows the results. (Materials used) Admixture A: calcium aluminate, main component C₁₂A₇,
Brain value 6100cm ^Two/ G Admixture B: alkali metal aluminate, commercially available aluminate
sodium

[0030]

[Table 2]

Example 3 100 parts by weight of aluminum sulfite, 500 parts by weight of admixture A, 50 parts by weight of admixture B and 50 parts by weight of the admixture shown in Table 2 were mixed with 100 parts by weight of cement to 10 parts by weight of cement. The same procedure as in Example 1 was performed except that parts by weight were used. Table 3 shows the results. (Materials used) Admixture C: Anhydrous gypsum ground product, Blaine value 5800c
m ² / g Admixture D: Commercial sodium carbonate Admixture E: Commercial silica fume Admixture F: Commercial aluminum sulfate Admixture G: Commercial sodium hydroxide Admixture H: Commercial sodium silicate

[0032]

[Table 3]

Example 4 A cement quick setting agent consisting of 100 parts by weight of aluminum sulfite, 500 parts by weight of admixture A, and 50 parts by weight of admixture B was used except that the amounts shown in Table 4 were used with respect to 100 parts by weight of cement. Was performed in the same manner as in Example 1. Table 4 shows the results
Shown in

[0034]

[Table 4]

Example 5 Cement: 400 kg / m ³ , fine aggregate: 1023 kg /
m ³ , coarse aggregate 693 kg / m ³ , water 220 kg / m ³ , and sprayed concrete was prepared. The sprayed concrete was air-fed under a condition of a spraying speed of 4 m ³ / h and a spraying pressure of 4 kg / cm ² by a concrete pump “Aliver 280”, and 100 parts by weight of aluminum sulfite was passed through one of the Y-shaped pipes provided on the way. And a cement quick-setting admixture consisting of an admixture in the amount shown in Table 5 with respect to 100 parts by weight of cement.
"Natom Cleat", a quick-set pressure feeder to be 10 parts by weight
And then mixed with the shotcrete to form a quick-setting shotcrete, and measured for compressive strength. Table 5 shows the results. (Materials used) Fine aggregate: River sand from Himekawa, Niigata Prefecture, surface water rate 4.0%, specific gravity 2.61 Coarse aggregate: gravel from Himekawa, Niigata prefecture, surface dry state, specific gravity 2.6
5. Maximum dimension 10 mm (Measurement method) Compressive strength: The prepared quick-setting concrete was sprayed. For one hour of age, using a pull-out mold specimen of 25 cm width x 25 cm length, cover the pin with quick-setting spray concrete from the surface of the pull-out mold, pull out the pin from the back side of the mold, and pull out strength at that time Was calculated, and the compressive strength was calculated from the formula: (compressive strength) = (pull-out strength) × 4 / (sample contact area). 50cm width after 1 day
Diameter 5 collected from a mold 50 cm long x 20 cm thick
A specimen having a size of cm × 10 cm in length was measured with a 20-ton pressure machine to determine the compressive strength.

[0036]

[Table 5]

Example 6 Using shotcrete in which coarse aggregate was replaced with alkali-reactive aggregate, 100 parts by weight of a cement quick-setting agent consisting of 100 parts by weight of aluminum sulfite and the amount of admixture shown in Table 6 was mixed with 100 parts by weight of cement. On the other hand, the procedure was performed in the same manner as in Example 5 except for using 10 parts by weight, and the length change was measured in order to examine the influence of the alkali-aggregate reaction. For comparison, the same procedure as in Example 5 was carried out except that a quick-setting binder consisting of 100 parts by weight of calcium aluminate and 20 parts by weight of sodium aluminate was used. Table 6 shows the results. (Materials used) Alkali-reactive aggregate: Aggregate containing opal sandstone (Measurement method) Length change: After spraying onto a mold 4 cm wide x 4 cm thick x 16 cm long, demolding, then at 20 ° C Cured in water for a predetermined period, and the change in length at each age was measured.

[0038]

[Table 6]

[0039]

By using the cement admixture of the present invention, a cement composition having excellent initial setting can be obtained, and deterioration of the cement composition due to the effect of alkali-aggregate reaction can be reduced.

Claims (2)

[Claims] 1. A cement admixture comprising aluminum sulfite. 2. A cement composition comprising the cement admixture according to claim 1.