JPH08310846A - Cement admixture, cement composition and injecting material composed thereof - Google Patents

Abstract

PURPOSE: To improve material separation resistance and strength exhibiting property by using a cement composition consisting of a cement admixture, containing a CaO-Al2 O3 -Li2 O based material, an inorganic sulfate, a coagulation adjusting agent and having a specific particle diameter, and a cement. CONSTITUTION: The cement composition is obtained by blending the cement admixture 100 pts.wt. in the sum of CaO-Al2 O3 -SiO2 -Li2 O based material obtained by blending a CaO raw material, an Al2 O3 raw material and an Li2 O raw material and heat treating at 1100-1800 deg.C, 1-15wt.% in Li2 O content, 1.5-3.0 in molar ratio CaO/Al2 O3 and <=40μm in max. particle diameter, 20-70 pts.wt. inorganic sulfate such as gypsum <=40μm in max. particle diameter and 0.5-5 pts.wt. coagulation adjusting agent of the organic acid and/or the salt and the alkali metal carbonate or the like by 10-50 pts.wt. to 100 pts.wt. cement composition composed of the cement such as various Portland cement <=40μm in max. particle diameter and the cement admixture. And the cement composition is used as the injecting material.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention mainly relates to a cement admixture, a cement composition, used in the field of civil engineering / construction,
And an injection material using the same.

[0002]

2. Description of the Related Art Various cement admixtures are used in the fields of civil engineering and construction. In particular, injecting materials are widely used for the purpose of water stoppage and ground stabilization at the gaps between soil particles in soil, the boundary between soil layers, or the cracks in rock. However, since the water-to-cement ratio is large, the injection material that is usually used has problems such as low material separation resistance, remarkably slow setting and hardening, and poor strength development.

Therefore, in order to solve the problems of these injection materials, a quick-hardening injection material having a calcium aluminate compound as a main component, which has a good injection property and an excellent initial strength development property, has been proposed. (Japanese Patent Laid-Open No. 3-88755, etc.). However, recently, there has been an increasing demand for improvement in the performance of injection materials, and the advent of injection materials satisfying the demand has been awaited.

The present inventor has made various efforts to solve the above problems, and as a result, by using a specific cement admixture as an injecting agent, a cement composition excellent in material separation resistance and strength development. The present invention has been completed based on the knowledge that the above can be achieved.

[0005]

A resolution means for] That is, the present invention, Li ₂ O content of 1-15 wt% of _{CaO-Al 2 O 3 -Li 2} O -based material, an inorganic acid salt, and contains the condensed modifier A cement admixture having a maximum particle size of 40 μm or less, which is a cement composition containing the cement admixture and a cement having a maximum particle size of 40 μm or less, and an injecting agent using the cement composition. is there.

The present invention will be described in more detail below.

Li ₂ O content used in the present invention 1 to 15% by weight
The CaO-Al ₂ O ₃ -Li ₂ O-based substance (hereinafter referred to as CAL) is obtained by blending a CaO raw material, an Al ₂ O ₃ raw material, and a Li ₂ O raw material and heat-treating them.

CaO raw materials include slaked lime, limestone, and calcium carbonate, and Al ₂ O ₃ raw materials include bauxite, aluminum residual ash, and alumina.
Examples of the Li ₂ O raw material include lithium salts such as Li ₂ CO ₃ and LiOH.

The heat treatment method at the time of CAL production is not particularly limited, and examples thereof include a firing method using a rotary kiln and a melting method using an electric furnace, and the heat treatment time is not particularly limited. Usually, the heat treatment temperature is preferably about 1,100 to 1,800 ° C, more preferably 1,200 to 1,700 ° C. If the temperature is lower than 1,100 ° C, unreacted raw materials may remain, and if the temperature exceeds 1,800 ° C, energy loss becomes large, which is not preferable in terms of cost. The method for cooling the heat-treated product is not particularly limited, and for example, any method such as a rapid cooling method using water or high-pressure air or a gradual cooling method by standing can be used.

The presence of other components or impurities is not particularly limited, and, for example, TiO ₂ , MgO, Fe ₂ O ₃ , Na ₂ O and K _{2 which} are expected to be mixed as other components are included. O, SiO ₂ , B
The presence of ₂ O ₃ , P ₂ O ₅ , F ₂ , SO _3, etc. has the effect of lowering the melting point of the fired product or the melt and increasing the activity of the fired product or the melt during the heat treatment of each raw material. There are also some preferable aspects from the above, and there is no problem as long as the object of the present invention is not substantially impaired.

[0011] the content of Li ₂ O of CAL is 1-15 wt%, the content of Li ₂ O is preferably 2 to 12 wt%, more preferably 3 to 9 wt%. If the Li ₂ O content is outside this range, the effects of the present invention may not be sufficiently obtained.

The ratio of CaO to Al ₂ O ₃ in CAL is not particularly limited, but the CaO / Al ₂ O ₃ molar ratio (hereinafter C
/ A molar ratio) is preferably 1.5 to 3.0, more preferably 2.0 to 2.8. If the C / A molar ratio is less than 1.5, the strength development may deteriorate, and if it exceeds 3.0, the workability of the cement kneaded product using the same may deteriorate.

In the present invention, CAL may be crystalline or amorphous, but it is preferable to use amorphous CAL from the viewpoint of material separation resistance and strength development.

Here, the term "amorphous" does not necessarily mean that everything is amorphous, and for example, it has a vitrification ratio of about 50% or more, preferably 70% or more.

The vitrification ratio (X) in the present invention is CAL
The powder obtained by heating at 1,000 ° C. for 3 hours and then cooling at a cooling rate of 5 ° C./min was used to determine the area S ₀ of the main peak of the crystalline mineral obtained by the powder X-ray diffraction method and the crystal in the CAL. From the area S of the main peak, X (%) = (1-S / S ₀ ) ×
Obtained as 100.

The particle size of CAL is not particularly limited, but the maximum particle size is preferably 40 μm or less, more preferably 20 μm or less, most preferably 10 μm or less. The maximum particle size is
If it exceeds 40 μm, injection into the ground or rock may be impossible. The fineness of CAL is 5 in terms of Blaine value.
It is preferably about 000 to 10,000 cm ² / g. If it is less than 5,000 cm ² / g, sufficient injectability may not be obtained, and if it exceeds 10,000 cm ² / g, further improvement of the effect may not be expected.

The inorganic sulfate used in the present invention is a general term for gypsum, aluminum sulfate, alkali metal sulfate and the like, and is not particularly limited,
The use of gypsum is preferable because the effect of the present invention is great and it is economical. Here, the gypsum is a generic term for anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum, and is not particularly limited, but since anhydrous gypsum has the greatest effect of the present invention. preferable. As anhydrous gypsum, for example, natural anhydrous gypsum produced naturally, anhydrous gypsum obtained by heat-treating semi-aqueous gypsum or dihydrate gypsum, and anhydrous gypsum generated as an industrial by-product can be used. The particle size of the inorganic sulfate is not particularly limited, but the maximum particle size is preferably 40 μm or less, more preferably 20 μm or less, most preferably 10 μm or less. Maximum particle size is 40μ
If it exceeds m, injection into the ground or rock may be impossible. In addition, the fineness of the inorganic sulfate is 5, Blaine value,
000 to 10,000 cm ² / g is preferable. If it is less than 5,000 cm ² / g, injectability may be poor, and if it exceeds 10,000 cm ² / g, further improvement of the effect may not be expected. The amount of the inorganic sulfate used is preferably 20 to 70 parts by weight, more preferably 30 to 60 parts by weight, based on 100 parts by weight of the cement admixture consisting of CAL, the inorganic sulfate and the setting modifier. If it is less than 20 parts by weight, sufficient strength enhancing effect may not be obtained, and if it exceeds 70 parts by weight, long-term durability may be deteriorated.

In the present invention, it is necessary to use a coagulation modifier together for the purpose of securing a certain working time, which is effective in facilitating the construction work.

Here, the setting regulator is, for example, an organic acid such as citric acid, tartaric acid, gluconic acid and malic acid or a salt thereof, phosphoric acid or a salt thereof, an alkali metal carbonate,
Alkali metal bicarbonate, and boric acid and the like,
Although not particularly limited, it is preferable to use an organic acid and / or a salt thereof in combination with an alkali metal carbonate from the viewpoint of good strength development. The amount of the coagulation modifier used cannot be unambiguously determined because it depends on the purpose or application of use, but normally, 0.5 to 5 parts by weight is preferable with respect to 100 parts by weight of the cement admixture, and 1 to 3 parts by weight is more preferable. If it is less than 0.5 part by weight, sufficient workability may not be obtained, and if it is used in excess of 5 parts by weight, strength development may be deteriorated.

The cement admixture of the present invention has a Li ₂ O content of 1
To 15% of _{CaO-Al 2 O 3 -Li 2} O -based material, an inorganic acid salt, and one comprising coagulation adjusting agent, it is less than or equal to the maximum particle size 40 [mu] m. The maximum particle size of the cement admixture of the present invention is
It is 40 μm or less, preferably 20 μm or less, and more preferably 10 μm or less. If the maximum particle size exceeds 40 μm, injection into the ground or rock may be impossible. Also, the fineness of cement admixture is 5,000 to 10,000 cm ² / g in terms of Blaine value.
Is preferred. If it is less than 5,000 cm ² / g, injectability may be poor, and if it exceeds 10,000 cm ² / g, further improvement of the effect may not be expected. The method for manufacturing a cement admixture of the present invention is not limited in particular, a maximum particle size of the content of Li ₂ O 1-15% by weight 40μm following _{CaO-Al 2 O 3 -Li 2} O -based material,
A method of mixing an inorganic sulfate having a maximum particle size of 40 μm or less and a coagulation modifier is also possible, and a Li ₂ O content of 1 to 15% by weight can be used.
A method in which a CaO-Al ₂ O ₃ -Li ₂ O-based substance, an inorganic sulfate, and a coagulation modifier are mixed and pulverized is also possible. The amount of the cement admixture used is preferably 10 to 50 parts by weight in 100 parts by weight of a cement composition consisting of cement and the cement admixture, and 20
-30 parts by weight is more preferred. If it is less than 10 parts by weight, the rapid hardening effect may not be sufficient, and if it exceeds 50 parts by weight, long-term durability may be deteriorated.

Examples of the cement include various types of portland cement such as normal, early strength, super early strength and moderate heat, and various mixed cements obtained by mixing these portland cements with a pozzolanic substance such as silica.

As the mixing device used for producing the cement admixture or the cement composition of the present invention, any existing mixing device can be used, for example, a tilting mixer, an omni mixer, a V-type mixer, and a Henschel. A mixer, a Nauta mixer or the like can be used. Also,
Mixing may mix each material at the time of construction,
A part or all of them may be mixed in advance.

In the present invention, in addition to cement and cement admixture, aggregates such as sand and gravel, water reducing agents, high-performance water reducing agents, A
E agent, AE water reducing agent, high performance AE water reducing agent, thickening agent, cement expanding agent, rust preventive agent, antifreezing agent, polymer emulsion, clay minerals such as bentonite and montmorillonite, zeolite, hydrotalcite, and hydrocalumite It is possible to use one or two or more of ion exchangers such as the above, inorganic phosphate, boric acid and the like within a range that does not substantially impair the object of the present invention.

[0024]

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 a Li ₂ O raw material were mixed and the temperature was 1,600 ° C.
The clinker obtained by quenching the melted material in the electric furnace of No.1 is crushed, and the maximum particle size is 40 μm or less, and the Blaine value is 6,500 ± 2.
Adjusted to 00 cm ² / g and various amorphous C as shown in Table 1
I got AL. The composition ratio of CAL was determined by chemical analysis.
50 parts by weight of this CAL and 50 parts by weight of inorganic sulfate are blended,
A cement composition having a maximum particle size of 40 μm or less and a Blaine value of 6,500 ± 200 cm ² / g was mixed and mixed with cement crushed to a maximum particle size of 40 μm or less to prepare a cement composition. 25 parts by weight of cement admixture in 100 parts by weight of the cement composition, 0.5 parts by weight of a setting modifier to 100 parts by weight of the cement composition, and a mortar mixer with a water / cement composition ratio of 300%. The mixture was kneaded for 60 seconds to prepare a cement pesto with a kneading temperature adjusted to 20 ° C. Using this cement paste, the compressive strength and the water separation rate for evaluating the material separation resistance were measured. The results are also shown in Table 1.

<Materials used> CaO raw material: Wako Pure Chemical Industries, Ltd. reagent first grade CaCO ₃ Al ₂ O ₃ raw material: Wako Pure Chemical Industries Ltd. reagent first grade Al ₂ O ₃ Li ₂ O raw material: Wako Pure Chemical Industries Ltd. Reagents made 1st class Li ₂ CO ₃ inorganic sulfate: natural anhydrous gypsum, maximum particle size 40μm or less,
Blaine value 5,640 cm ² / g Condensation modifier: A mixture of citric acid of primary reagent and potassium carbonate in a weight ratio of 40/60 Cement: Denki Kagaku Kogyo normal Portland cement Water: Tap water

<Test method> Compressive strength: A test piece of 4 × 4 × 16 cm was prepared, demolded after 1 day of age, and aged in water at 20 ° C. for measurement. Separation rate of water: Measurement of material separation resistance, preparation Put the cement paste into a polyethylene φ5 cm bag up to a height of 15 cm, and after 24 hours, measure the height of the floating water that has been separated, and calculate the separated water ratio from (height of floating water / 15) × 100.

[0028]

[Table 1]

Example 2 A CaO raw material, an Al ₂ O ₃ raw material, and a Li ₂ O raw material were mixed and the temperature was 1,600 ° C.
The same procedure as in Example 1 was carried out except that the molten material melted in the electric furnace was gradually cooled to obtain various crystalline CALs as shown in Table 2. The results are also shown in Table 2.

[0030]

[Table 2]

Example 3 Similar to Example 1 except that CAL having a C / A molar ratio of 2.5 and a Li ₂ O content of 5% by weight was used and CAL and an inorganic sulfate were blended as shown in Table 3. Went to. The results are also shown in Table 3.

[0032]

[Table 3]

Example 4 CAL having a C / A molar ratio of 2.5 and a Li ₂ O content of 5% by weight was used, and the cement admixture in 100 parts by weight of the cement composition was compounded as shown in Table 4. The same procedure as in Example 1 was performed. The results are also shown in Table 4.

[0034]

[Table 4]

Example 5 CAL having a C / A molar ratio of 2.5 and a Li ₂ O content of 5% by weight was used, and a cement admixture having the maximum particle size shown in Table 5 was blended to obtain a compressive strength, a separated water ratio, and It carried out like Example 1 except having measured the penetration depth for evaluating pouring penetration.
The results are also shown in Table 5.

<Test Method> Penetration Depth: Injection permeability, standing a cylinder of φ10 × 20 cm, laying a cloth on the bottom, specific gravity 2.63, grain size 0.3 to 1.2 mm, and porosity 43.
% Sand is filled from the bottom to a height of 15 cm, 500 cc of the prepared cement paste for injection is poured from the top of the cylinder, and after 24 hours, it is demolded and measured.

[0037]

[Table 5]

[0038]

EFFECT OF THE INVENTION By using the cement admixture of the present invention, a cement composition having excellent resistance to material separation and strength development can be obtained.

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Claims (3)

[Claims] 1. A CaO-Al ₂ O ₃ -Li having a Li ₂ O content of 1 to 15% by weight.
A cement admixture containing a ₂ O-based substance, an inorganic sulfate, and a coagulation modifier and having a maximum particle size of 40 μm or less. 2. A cement composition comprising the cement admixture according to claim 1 and a cement having a maximum particle size of 40 μm or less. 3. An injectable material comprising the cement composition according to claim 2.