JPH08119698A - Cement accelerator and cement composition - Google Patents

Abstract

PURPOSE: To obtain a cement accelerator and a cement composition usable in civil engineering construction field, especially for spraying for tunnel and for cut-off of sump water and good in quick setting property, strong to sump water, profitability and quick setting property at low temp. CONSTITUTION: This cement accelerator is a CaO-Al2 O3 -R2 O based calcium aluminate obtained by heat treating CaO, Al2 O3 and R2 O each as starting material, and is incorporated with the calcium aluminate containing >=1wt.% two or more kinds of alkali metal oxides in the calcium aluminate and inorg. salts. This cement composition is constituted by using the accelerator together with the cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement quick-setting material mainly used in the fields of civil engineering and construction, and more particularly to a cement quick-setting material used for spraying tunnels and stopping spring water.

[0002]

[Its Problems prior art Conventionally, as a concrete quick-setting admixture using calcium aluminate, CaO-Na ₂ O-A
l ₂ O ₃ based sintered product or a melt, calcium sulfate, and alkali metal which salt was used has been proposed (JP-A-4-5
5351 publication). However, this calcium aluminate has a relatively large amount of Na ₂ O, the sodium is soluble, and there is a problem that an alkaline aggregate reaction occurs.

When the sprayed concrete undergoes an alkali-aggregate reaction, not only the durability as a concrete structure is deteriorated, but also springs are generated from cracks generated by the alkali-aggregate reaction.

Further, conventional cement quick-setting materials include, for example,
As a spraying material for tunnels, it took several minutes to set, there was a problem that it caused a bounce phenomenon without sufficient adhesion strength to the ground, a large rebound amount, and it was not always economical.

Furthermore, there are problems that it is not suitable for tunnels with spring water, and that the properties of rapid setting and strength development deteriorate in cold regions.

As a result of various efforts to solve the above problems, the present inventor completed the present invention by finding that the above problems can be solved by using a specific cement quick-setting material. Came to do.

[0007]

[Means for Solving the Problems] That is, the present invention provides a CaO source.
Fee, Al₂O₃Raw material and R₂CaO-Al formed by heat treatment of O raw material ₂
O₃-R₂O-based calcium aluminate,
1 or more of two or more alkali metal oxides in the mualuminate
Calcium aluminate containing more than weight% and inorganic salt
A cement quick-setting material containing
A cement composition containing the cement quick-setting material.
You.

The present invention will be described in more detail below.

The calcium aluminate of the present invention is CaO.
CaO-A obtained by heat treating raw materials, Al ₂ O ₃ raw materials, and R ₂ O raw materials
a l ₂ O ₃ -R ₂ O-based calcium aluminate, calcium aluminate containing at least two alkali metal oxides in the calcium aluminate 1 wt% or more.

The calcium aluminate of the present invention (hereinafter C
The raw material (referred to as A) is composed of CaO raw material, Al ₂ O ₃ raw material, and R ₂ O raw material of alkali raw material, and is not particularly limited. For example, CaO raw material includes slaked lime and limestone powder. Examples of ₂ O ₃ raw materials include bauxite and aluminum residual ash, and examples of R ₂ O raw materials include alkali metal carbonates and feldspars.

The heat treatment method of CA is not particularly limited, and examples thereof include a method of firing and / or melting using a kiln, an electric furnace or the like.
At least it is preferable to melt. The firing and / or melting time is also not particularly limited. The method for cooling the fired product and the melt is not particularly limited,
For example, any method such as a rapid cooling method using water or high-pressure air or a slow cooling method using natural cooling can be used.

Further, as other components or impurities, for example, SiO ₂ , P ₂ O ₅ , B ₂ O ₃ , TiO ₂ , MgO, F from industrial raw materials can be used.
Mixing of e ₂ O ₃ , F ₂ and SO ₃ is expected. The presence of these impurities and the like is preferably as small as possible, but there are also favorable aspects such as the effect of lowering the melting point during the production of clinker and the ability to enhance the activity of the clinker, which substantially obstructs the object of the present invention. If it is not within the range, for example, the total amount of these impurities is less than about 10% by weight, no problem will occur.

The amount of two or more kinds of alkali metal oxides in the heat-treated product is 1% by weight or more as alkali metal oxide, preferably 2 to 15% by weight, more preferably 5 to 12% by weight. If it is less than 1 part by weight, the quick-setting property is not sufficient.
Even if it is used in excess of weight%, it cannot be expected to improve the quick-setting property.

In the present invention, as the alkali metal of the R ₂ O raw material, there are sodium, potassium, and lithium. However, since the effect of the present invention is remarkable, and from the economical aspect, it is possible to use sodium and potassium. The use of certain oxides is preferred. When sodium oxide is used alone, it tends to cause an alkali-aggregate reaction, and its quick-setting property is not sufficient. Further, when potassium oxide is used alone, the quick-setting property is good, but a large amount must be used, and there is a problem in terms of economy. The ratio of the two or more kinds of alkali metal oxides of the present invention is not particularly limited. For example, in the case of sodium and potassium oxides, the weight ratio of the oxides is 1: 1. Is most preferable from the economical point of view.

The CA of the present invention may be either crystalline or amorphous, but it is preferable to use amorphous CA in order to exhibit a good quick-setting property.

Here, the term "amorphous" does not necessarily mean that all of them are amorphous. For example, those having a vitrification rate of 50% or more are preferable, and those of 70% or more are more preferable. Vitrification rate is 50
If it is less than%, the reactivity tends to decrease, and the quick-setting property tends to be insufficient.

The vitrification rate (X) means that CA is 3 at 1,000 ° C.
After heating for an hour and then slowly cooling at a cooling rate of 5 ° C./min, X was calculated from the main peak area S _{0 of} the crystal minerals and the main peak area S of the crystals in CA, which were obtained by powder X-ray diffractometry.
(%) = (1-S / S ₀ ) × 100.

The molar ratio of CaO / Al ₂ O _{3 in} CA of the present invention is 1
-3 are preferable, and 1.5-2 are more preferable. If it is less than 1, the quick-setting property is not sufficient, and if it exceeds 3, the durability may deteriorate.

The particle size of the CA of the present invention is not particularly limited, but it is preferable that the Blaine value is in the range of about 3,000 to 9,000 cm ² / g. If it is less than 3,000 cm ² / g, sufficient quick-setting property may not be obtained, and if it exceeds 9,000 cm ² / g, further effects of quick-setting property and strength development cannot be expected.

Examples of the inorganic salts of the present invention include alkali metal aluminates such as sodium aluminate and potassium aluminate, alkali metal carbonates such as sodium carbonate and potassium carbonate, sodium nitrate, potassium nitrate, sodium nitrite, and Alkali metal nitrates such as potassium nitrite, sodium sulfate, aluminum sulfate,
And inorganic sulfate such as calcined alum, anhydrous gypsum,
Gypsums such as hemihydrate gypsum and dihydrate gypsum, and hydroxides such as calcium hydroxide, sodium hydroxide, and potassium hydroxide are included.

In the present invention, one kind or two or more kinds of these inorganic salts can be used in combination depending on the purpose of use. For example, when CA of the present invention is used in combination with an alkali metal aluminate or an alkali metal carbonate, it is possible to obtain a tunnel spraying material having good quick setting property, and the CA of the present invention and an alkali metal aluminate are used. When used in combination with nitrates, it can be used as a tunnel spray material with good quick-setting properties in cold regions. When CA of the present invention is used in combination with calcined alum, a highly safe tunnel spray material with low alkalinity can be obtained. Further, the combined use of the inorganic salts and gypsum is particularly preferable in the field of tunnel spraying materials and the like from the viewpoint of good strength development.

The amount of the inorganic salt used is preferably 10 to 60 parts by weight, and more preferably 20 to 40 parts by weight, based on 100 parts by weight of the cement quick-setting material composed of CA and the inorganic salt. If the amount of the inorganic salt used is outside this range, the quick-setting property and the strength development property may deteriorate.

The cement quick-setting material of the present invention comprises CaO raw material, Al₂
O₃Raw material and R₂CaO-Al formed by heat treatment of O raw material₂O₃-R₂O
Of which the main component is CA and inorganic salts,
A contains at least 1% by weight of two or more kinds of alkali metal oxides.
I have. Use the particle size of the cement quick-setting material
There is no particular limitation as it depends on the purpose and application.
However, the Blaine value is usually 3,000 to 9,000 cm.²/ g is preferred
Yes. 3,000 cm ²If it is less than / g, the quick-setting property may deteriorate,
9,000 cm²Even if used over / g, further effects can be expected
Absent. The amount of cement quick-setting material used is
3 to 15 parts by weight are preferable in a total of 100 parts by weight of quick-setting materials, and 5
-10 parts by weight is more preferred. If less than 3 parts by weight
If it is not sufficient and durability exceeds 15 parts by weight,
There is a match.

Examples of the cement used in the present invention include various portland cements such as normal, early strength, ultrafast strength, and moderate heat, and various mixed cements obtained by mixing these portland cements with a pozzolanic substance.

As the mixing apparatus used for producing the cement quick-setting material of the present invention, any existing stirring apparatus can be used, for example, a tilting mixer, an omni mixer, a V mixer.
A mold mixer, a Henschel mixer, a Nauta mixer or the like can be used. For the mixing, the respective materials may be mixed at the time of construction, or a part or all of them may be mixed in advance.

In the present invention, in addition to the cement and the cement quick-setting material, a setting regulator, a water reducing agent, a high-performance water reducing agent, an AE agent, A
E water reducing agent, high-performance AE water reducing agent, thickening agent, aggregate such as sand and gravel, cement expanding material, rust preventive, antifreezing agent, polymer emulsion, clay mineral such as bentonite and montmorillonite, zeolite, hydrotalcite , And an ion exchanger such as hydrocalumite, an inorganic phosphate, and boric acid, etc., can be used in combination within a range not substantially impairing the object of the present invention.

[0027]

The present invention will be described in detail below with reference to examples.

Example 1 A CaO raw material, an Al ₂ O ₃ raw material, and an R ₂ O raw material were mixed, and the clinker obtained by rapidly cooling the melt melted at 1,600 ° C. by a high pressure air method using an electric furnace was crushed. , Blaine value 5,000 ± 200 cm
Various CAs shown in Table 1 were obtained after adjusting to ² / g. CA
The composition ratio of was calculated from the values obtained by chemical analysis. CA
70 parts by weight and 30 parts by weight of inorganic salt a were mixed to prepare a cement quick-setting material. At room temperature of 20 ° C, 7 parts by weight of cement quick-setting material is mixed in 100 parts by weight of binding material consisting of cement and cement quick-setting material, binder / sand ratio = 1/2, water / bonding material ratio = 50
% Mortar was prepared and the setting time of this mortar was measured by Proctor penetration resistance. The results are also shown in Table 1. The mortar was kneaded for 10 seconds, water was added, and the mixture was quickly kneaded for 10 seconds.

<Materials used> CaO raw material: Wako Pure Chemical Industries Ltd. reagent grade 1, CaO Al ₂ O ₃ raw material: Wako Pure Chemical Industries Ltd reagent grade 1, Al ₂ O ₃ R ₂ O raw material: Wako Pure Chemical Industries Ltd. Reagent grade 1, Na ₂ CO ₃ R ₂ O raw material: Wako Pure Chemical Industries reagent grade 1, K ₂ CO ₃ inorganic salts a: 20 grade parts of reagent grade sodium aluminate and reagent grade potassium carbonate Mixture with 80 parts by weight Cement: Denki Kagaku Kogyo normal portland cement Sand: Niigata prefecture Himekawa river sand, FM 2.8 Water: Tap water

<Measurement method> Setting time: Measured according to the proctor penetration resistance method of ASTM C 403-65 T. Vitrification rate (X): CA was heated at 1,000 ° C. for 3 hours, then slowly cooled at a cooling rate of 5 ° C./min, and the area S ₀ and CA of the main peak of the crystalline mineral obtained by a powder X-ray diffraction method. From the area S of the main peak of the crystal inside, X (%) = (1-S / S ₀ ).
Calculated according to the formula of × 100

[0031]

[Table 1]

Example 2 CA was used in which the molar ratio of CaO / Al ₂ O ₃ was 1.7, and the amount of Na ₂ O and the amount of K ₂ O were each 5% by weight. The same procedure as in Example 1 was performed except that the change was made as shown in FIG. The results are also shown in Table 2.

[0033]

[Table 2]

Example 3 CA was used in which the molar ratio of CaO / Al ₂ O ₃ was 1.7 and the amount of Na ₂ O and K ₂ O were each 5% by weight. The same procedure as in Example 1 was performed except that the changes were as shown.
The results are also shown in Table 3.

[0035]

[Table 3]

Example 4 Industrial CaO raw material, Al₂O₃Raw material and R₂Using O raw material
CaO / Al as in Example 1 ₂O₃Molar ratio is 1.7, Na₂O amount and K₂O
CA was obtained in amounts of 5% by weight each. Obtained using industrial raw materials
CA is a small amount of TiO₂, B₂O₃, Fe₂O₃, P₂O_Five, And Na₂O
Etc. are included. However, Na₂O was less than 1% by weight.
At room temperature of 20 ° C, 70 parts by weight of this CA and various inorganic substances shown in Table 4
Procactor of cement quick-setting material obtained by mixing 30 parts by weight of salt
-Measure the penetration resistance value in the same manner as in Example 1, and
It was measured. The obtained cement quick-setting material is cemented with cement.
7 parts by weight in 100 parts by weight of binder made of quick-setting material
However, the unit amount of each material is 360 kg / m of binder.³, Coarse aggregate 756kg /
m³, Fine aggregate 1,130kg / m³, And water 162kg / m³With the combination of
A cleat was prepared. Spray this concrete and drop
Measure the amount of concrete that was rebound as the rebound rate (%)
Was. For comparison, the same procedure was performed using a commercially available quick-setting material.
The results are also shown in Table 4.

<Materials used> CaO raw material: Limestone Al ₂ O ₃ raw material from Omi Mine, Denki Kagaku Kogyo Co., Ltd .: Commercial bauxite R ₂ O raw material: Commercial soda ash R ₂ O raw material: Commercial potassium carbonate Inorganic salts b: Reagent first grade A mixture of 85 parts by weight of potassium aluminate and 15 parts by weight of first-grade reagent sodium nitrate Inorganic salt c: Reagent first-grade potassium alum heat-treated at 600 ° C for 1 hour Inorganic salt d: Reagent first-grade aluminate Mixture of 30 parts by weight of sodium, 60 parts by weight of reagent grade 1 potassium carbonate, and 10 parts by weight of natural anhydrous gypsum Inorganic salts e: Reagent grade 1 potassium carbonate Commercial quick-setting material: Onoda Cement's trade name "Onoda T- Roc
k ”, the main component calcium aluminate cement: ordinary Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Coarse aggregate: Niigata prefecture Himekawa river gravel, Gmax = 10mm Fine aggregate: Niigata prefecture Himekawa river sand, FM 2.8 Water: tap water

<Measurement Method> pH: 0.5 g of cement quick-setting material was added to 500 cc of pure water,
Measure after stirring and dissolving for 1 minute

[0039]

[Table 4]

Example 5 Example 4 was repeated except that the inorganic salt b was used and the room temperature was 5 ° C. The results are shown in Table 5.

[0041]

[Table 5]

[0042]

EFFECTS OF THE INVENTION By using the cement quick-setting material of the present invention, the effects such as good quick-setting property, strong resistance to spring water, economical, and good quick-setting property at low temperature are obtained. Play.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Koichi Ishibashi 2209 Aomi, Aomi-cho, Nishikubiki-gun, Niigata Prefecture Inside the Aomi Plant, Electrochemical Industry Co., Ltd. (72) Naotaka Kondo 2209 Omi, Aomi, Aomi-cho, Nishikubiki-gun, Niigata Electric Chemical Industry Co., Ltd.Aomi Plant (72) Hirofumi Tanaka, 2209 Aomi, Aomi Town, Nishikubiki-gun, Niigata Prefecture Electrochemical Industry Co., Ltd. Aomi Plant, Kamihiro Aizawa 2209 Aomi, Aomi Town, Nishikubiki District, Niigata Prefecture Denki Kagaku Co., Ltd. Aomi factory

Claims (2)

[Claims] 1. CaO raw material, Al₂O₃Raw material and R₂O raw material heat
Processed CaO-Al ₂O₃-R₂O-based calcium aluminum
And two or more kinds of calcium in the calcium aluminate.
Calcium acetate containing 1% by weight or more of Lucari metal oxide
Quick setting of cement containing luminate and inorganic salts
Material. 2. A cement composition containing cement and the cement quick-setting material according to claim 1.