JP3340258B2 - Cement admixture and cement composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cement admixture and a cement composition mainly used in the civil engineering and construction industries.

[0002]

2. Description of the Related Art Various cement admixtures are used in the civil engineering and construction industries. In particular, the gap between soil particles in the soil, the layer boundary of the soil layer, or cracks in the bedrock, etc.
Injectables are widely used for the purpose of stopping water and stabilizing the ground. However, since the injection material usually used has a large water-cement ratio, there are problems that the setting and hardening are remarkably slow and the strength development is poor.
Therefore, in order to solve the problems of these injection materials,
There is a need for a rapidly hardened injection material.

As a rapidly hardening injection material, there has been proposed a rapidly hardening injection material having a calcium aluminate compound as a main component (Japanese Patent Laid-Open No. 4-280844). This hydraulic injection material has good injection properties and excellent initial strength development, but in some composition ranges,
There was a problem that the strength growth after one day of material age was poor. In recent years, there has been an increasing demand for improvements in performance such as the strength of the injected material, and the emergence of an injected material that satisfies the demand has been awaited.

The present inventor has conducted various studies to solve the above-mentioned problems, and as a result, by using a specific cement admixture, particularly as an injection material, a cement composition having excellent strength development and material separation resistance. The inventor has found that the present invention can be used to complete the present invention.

[0005]

That is, the present invention provides CaO / A
The main component is an amorphous calcium aluminate phosphate having an l ₂ O ₃ molar ratio of 2.5 to 3.5, a P ₂ O ₅ content of 2 to 20% by weight, and a maximum particle size of 40 μ or less, and an inorganic sulfate. It is a cement admixture, and is a cement composition containing a cement having a maximum particle size of 40 μm or less and the cement admixture.

Hereinafter, the present invention will be described in more detail.

The amorphous calcium aluminate phosphate (hereinafter referred to as A-CAP) of the present invention has a CaO / Al ₂ O ₃ molar ratio of 2.5 to 3.5 and contains 2 to 20% by weight of P ₂ O _5. Is what you do. CaO / Al ₂ O ₃ molar ratio is preferably 2.8 to 3.2. If it is less than 2.5, the strength development in the middle to long term may deteriorate, and if the CaO / Al ₂ O ₃ molar ratio exceeds 3.5, the dimensional stability and the workability of the cement kneaded material using this decrease. May be. Further, the P ₂ O ₅ content is 5 to 10
% By weight is preferred. If P ₂ O ₅ is not in the above range, the effects of the present invention may not be sufficiently obtained.

In the present invention, the term "amorphous" does not need to be all amorphous. For example, it is about 50% or more in terms of vitrification rate, and preferably 70% or more.

The vitrification rate (X) referred to in the present invention is A-CA
P was heated at 1,000 ° C. for 3 hours, and then gradually 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 main area of the crystal in A-CAP were determined. Using the peak area S, it can be calculated from the formula of X (%) = (1−S / S ₀ ) × 100.

The raw material of A-CAP used in the present invention is not particularly limited. For example, slaked lime or limestone powder is used as a CaO raw material, and bauxite or aluminum residual ash is used as an Al ₂ O ₃ raw material. Phosphate such as calcium pyrophosphate, phosphate rock or the like can be used as the ₂ O ₅ raw material. A
The method of heat-treating the CAP raw material is not particularly limited, but for example, a rotary kiln, an electric furnace, or the like can be used for firing or melting, and the firing or melting time is not particularly limited. . The method for cooling the calcined product or the melt is not particularly limited, and 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, the presence of other components or impurities in the raw material is not particularly limited. For example, SiO ₂ , B ₂ O ₃ , TiO ₂ , Mg
O, Fe ₂ O ₃ , Na ₂ O, K ₂ O, F ₂ , and SO ₃ are expected to be mixed. Its presence is preferred because it has the effect of lowering it and has the effect of increasing the activity of the calcined product or the melt, and its presence in an amount that does not substantially inhibit the object of the present invention does not matter.

The maximum particle size of the A-CAP of the present invention is 40 μm or less, preferably 20 μm or less, more preferably 10 μm or less. If the maximum particle size exceeds 40μ, injection into the ground or rock may not be possible. The fineness of A-CAP is preferably in the range of about 5,000 to 10,000 cm ² / g in Blaine value. 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 effects of rapid hardening and strength development cannot 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.
It is preferable to use gypsum because the effects of the present invention are large and economical. Here, examples of the gypsum include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum, and among them, the use of anhydrous gypsum is preferred because the effect of the present invention is the greatest.
As the anhydrous gypsum, for example, in addition to natural anhydrous gypsum naturally produced, those obtained by heat-dehydrating hemihydrate gypsum or dihydrate gypsum, and those generated as industrial by-products can be used. The maximum particle size of the inorganic sulfate is 40 μm or less, preferably 20 μm or less, more preferably 10 μm or less. If the maximum particle size exceeds 40μ, injection into the ground or rock may not be possible. The fineness of the inorganic sulfate is preferably 5,000 to 10,000 cm ² / g in Blaine value. 5,000c
m is less than ² / g may injecting property deteriorates, 10,000 cm ² /
Even if it exceeds g, further effects of rapid hardening and strength development cannot 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, per 100 parts by weight of the cement admixture comprising A-CAP and the inorganic sulfate. If the amount is less than 20 parts by weight, a sufficient strength enhancing effect may not be obtained,
If it exceeds 70 parts by weight, long-term durability may be deteriorated.

In the present invention, in order to secure a certain working time, it is necessary to use a coagulation adjusting agent in combination in order to facilitate the construction. Here, the setting regulator is not particularly limited, for example, citric acid,
Tartaric acid, gluconic acid, and organic acids such as malic acid or a salt thereof, phosphoric acid or a salt thereof, an alkali metal carbonate, an alkali metal bicarbonate, and boric acid. It is preferable to use these salts in combination with an alkali metal carbonate, since the strength can be improved. Since the amount of the setting modifier depends on the purpose and application of the setting agent, it cannot be uniquely defined, but usually,
The range is preferably 0.5 to 5 parts by weight, more preferably 1 to 3 parts by weight, based on 100 parts by weight of the cement admixture. If the amount is less than 0.5 part by weight, sufficient workability may not be obtained, and if the amount is more than 5 parts by weight, strength development may be reduced.

The maximum particle size of the cement admixture of the present invention is 40 μm.
Or less, preferably 20 μm or less, more preferably 10 μm or less. If the maximum particle size exceeds 40μ, injection into the ground or rock may not be possible. The fineness of the cement admixture is preferably in the range of 5,000 to 10,000 cm ² / g in Blaine value. If it is less than 5,000 cm ² / g, the injectability may be poor, and even if it exceeds 10,000 cm ² / g, further effects cannot be expected. The amount of the cement admixture of the present invention is 100% of the binder consisting of cement and the cement admixture.
In the weight parts, 10 to 50 parts by weight is preferable, and 20 to 30 parts by weight is more preferable. If the amount is less than 10 parts by weight, the rapid hardening effect is not sufficient, and if it exceeds 50 parts by weight, long-term durability may deteriorate.

[0015] Examples of the cement include various portland cements such as ordinary, high-strength, ultra-high-strength, and moderate heat, and various mixed cements obtained by mixing a pozzolanic substance with these portland cements.

In the present invention, in addition to cement and cement admixture, water reducing agent, high performance water reducing agent, AE agent, AE water reducing agent, high performance AE water reducing agent, thickener, aggregate such as sand and gravel, cement One or two or more of expansive materials, rust preventives, antifreezes, polymer emulsions, clay minerals such as bentonite and montmorillonite, and ion exchangers such as zeolite, hydrotalcite and hydrocalmite are used. It is possible to use them together within a range that does not substantially inhibit the object of the invention.

As the mixing and kneading apparatus used for producing the cement admixture and the cement composition of the present invention, any existing stirring apparatus can be used. For example, an inclined mixer, an omni mixer, a V-type mixer , Henschel mixer, Nauter mixer and the like can be used. The mixing may be performed by mixing the respective materials at the time of construction, or a part or all of them may be mixed in advance. Also, the curing method is not particularly limited, and a generally performed curing method is applicable.

[0018]

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

Example 1 A CaO raw material, an Al ₂ O ₃ raw material, and a P ₂ O ₅ raw material were mixed, and the melt melted at 1,600 ° C. was quenched by a high-pressure air method using an electric furnace to obtain clinker. The obtained clinker is pulverized, the maximum particle size is 40μ or less, the fineness is 6,500 ± 200 cm in Blaine value.
^By adjusting to ² / g, various A-CAPs as shown in Table 1 were obtained. The composition ratio of A-CAP is a value determined by chemical analysis. A-CAP (50 parts by weight) and inorganic sulfate a (50 parts by weight) were blended, and the maximum particle size was 40 μm or less, and the Blaine value was 4,500 ± 200 cm.
^{A 2} / g cement admixture was prepared and mixed with cement pulverized to 40 μ or less to prepare a binder. The compounding ratio in the binder was 25 parts by weight of the cement admixture in 100 parts by weight of the binder, 1 part by weight of the setting modifier A was added to 100 parts by weight of the binder, and the water / binder ratio was 300. %, And kneaded with a mortar mixer for 60 seconds to obtain a cement paste adjusted to a kneading temperature of 20 ° C. Using this cement paste,
The compression strength and the water separation were measured. The results are also shown in Table 1.

<Materials Used> CaO raw material: Reagent first grade CaO Al ₂ O ₃ raw material manufactured by Wako Pure Chemical Industries, Ltd. Reagent first grade Al ₂ O ₃ P ₂ O ₅ raw material manufactured by Wako Pure Chemical Industries, Ltd .: Wako Pure Chemical Industries, Ltd. Reagent 1st grade P ₂ O ₅ Inorganic sulfate: Natural anhydrous gypsum Coagulation regulator: Mixture of 40 parts by weight of reagent 1st grade citric acid and 60 parts by weight of reagent 1st grade potassium carbonate Cement: Normal manufactured by Denki Kagaku Kogyo Portland cement crushed product of 40μ or less Water: Tap water

<Measurement Method> A specimen having a compressive strength of 4 × 4 × 16 cm was prepared and subjected to JIS A-52.
Measurement according to 01 Separation water rate: Put the adjusted cement paste into a polyethylene φ5 cm bag up to a height of 15 cm, and after 24 hours, measure the height of the separated floating water, and calculate ((height of floating water / 15 ) × 100
Was determined as the water separation rate.

[0022]

[Table 1]

Example 2 A-A with a CaO / Al ₂ O ₃ molar ratio of 3.0 and a P ₂ O ₅ content of 7% by weight
The procedure was performed in the same manner as in Example 1 except that CAP was used and the amounts of A-CAP and inorganic sulfate were changed. Table 2 shows the results
Shown in

[0024]

[Table 2]

Example 3 Example 2 except that the amount of cement admixture used was changed.
The same was done. Table 3 shows the results.

[0026]

[Table 3]

Example 4 The same procedure as in Example 2 was carried out except that the maximum particle size of the cement admixture was changed and the compressive strength, the water separation rate, and the injection permeability were measured. The results are also shown in Table 4.

<Measurement method> Injection permeability: A cylinder of φ10 × 20 cm was erected, a cloth was laid on the bottom, specific gravity 2.63, maximum particle size 0.3 to 1.2 mm, and porosity per unit volume 43%. Fill the sand with a height of 15 cm from the bottom, pour 500 cc of the prepared cement paste for injection from the top of the cylinder, remove the mold 24 hours later, and measure the injection permeability

[0029]

[Table 4]

[0030]

The use of the cement admixture of the present invention, particularly as an injection material, provides a cement composition having good strength development and high material separation resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C09K 17/10 C09K 17/10 P E02D 3/12 E02D 3/12 // C04B 103: 12 C04B 103: 12 C09K 103: 00 C09K 103: 00 (56) References JP-A-59-184755 (JP, A) JP-A-7-61846 (JP, A) JP-B-46-42711 (JP, B1) (58) Fields investigated (Int. Cl. ^7, DB name) C04B 22/16 C04B 22/14 C04B 22/08

Claims (2)

(57) [Claims] An amorphous calcium aluminate phosphate having a CaO / Al ₂ O ₃ molar ratio of 2.5 to 3.5, a P ₂ O ₅ content of 2 to 20% by weight, and a maximum particle size of 40 μ or less, and inorganic sulfuric acid. A cement admixture mainly composed of salt. 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.