JP2000272943A - Cement admixture, cement composition, and grout material - Google Patents

Abstract

(57) [Abstract] [Problem] Based on inexpensive material composition, high fluidity,
No material separation or bleeding occurs while having the expansion performance.Also, a pot life of 30 minutes or more is secured, and a compressive strength of about ² N / mm2 is developed in 3 hours. To provide a cement admixture, a cement composition, and a grout material used in a place where shrinkage is required. SOLUTION: A cement admixture containing calcium aluminate, gypsum, an expanding material, and a clay mineral, a cement, a fine aggregate, a cement composition containing the cement admixture, and containing the cement composition And a grout material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture, a cement composition, and a grout material which are used mainly in the civil engineering and construction industries, particularly in places where early strength development and no shrinkage are required. .

[0002]

2. Description of the Related Art Grouting materials are used in large quantities in the civil engineering and construction industries. In particular, there are a wide variety of applications, such as filling gaps under concrete paving slabs in airports, ports, roads, and the like, and filling gaps between supports and ground in tunnel construction. And the grout material used for these applications expresses strength in a short time, there is no bleeding, and it does not shrink.
The demands are becoming ever more stringent, such as extremely good fluidity and reduced material costs per unit volume. As effective means for satisfying these requirements, it is conceivable to use a mortar containing aggregate or to increase the amount of water per unit volume. However, conventional mortars made of powdery hydraulic material such as cement and aggregates cannot be used due to separation of materials when the ratio of water / hydraulic material is increased, particularly when the amount of aggregate is increased. Had a problem that remarkable sedimentation of the aggregate occurred.

In order to obtain high fluidity without separating materials, not only expensive materials such as cement milk, synthetic resin and cement asphalt mortar which do not contain aggregate must be used, but also the bone used. There is a problem that the material itself fills the gap of the check valve, and the amount of cement milk flows out of the gap of the check valve, so that a simple check valve or the like serving to prevent the backflow of mortar cannot be used.

The inventor of the present invention has conducted various studies to solve the above-mentioned problems, and as a result, obtained a finding that can solve the above-mentioned problems by using a specific cement admixture, thereby completing the present invention.

[0005]

That is, the present invention relates to a cement admixture containing calcium aluminate, gypsum, an expansive material, and a clay mineral, comprising cement, fine aggregate, and the cement admixture. A cement composition containing the cement composition, and a grout material containing the cement composition.

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

The calcium aluminate used in the present invention is obtained by melting a CaO raw material or an Al ₂ O ₃ raw material with an electric furnace or the like.
Or obtained by firing, 12CaO ・ 7Al ₂ O ₃ (C ₁₂ A ₇ )
And the like. Calcium aluminate (hereinafter referred to as CA
) Is preferably 20 to 70% by weight.
5 to 65% by weight is more preferred. If the amount is less than 20% by weight, the short-time strength may be insufficient. If the amount exceeds 70% by weight, it is difficult to control the setting time, and the strength development after curing may be poor. The CA may contain an alkali such as Na ₂ O or K ₂ O, or a component such as SiO ₂ , MgO, or CaF ₂ , and metallurgical slag may be used. As CA, either crystalline or amorphous can be used, but the use of amorphous is preferred. CA fineness is preferably 2,000 cm ² / g or more in consideration of initial strength development,
More preferably, 4,000 to 8,000 cm ² / g, but fine powder can also be used.

[0008] The gypsum used in the present invention is not particularly limited, and any of gypsum dihydrate, hemihydrate gypsum, type II anhydrous gypsum, and type III anhydrous gypsum can be used. , Phosphoric acid, excretion, and chemical gypsum such as gypsum
Alternatively, those obtained by heat-treating these can also be used, and are not affected by the type or amount of impurities usually contained. Of these, from the viewpoint of initial strength development and workability
Type II anhydrous gypsum is particularly preferred. The amount of gypsum used is
CA 100 parts by weight, preferably 10 to 400 parts by weight, 50
~ 200 parts by weight is more preferred. If the amount of gypsum is out of this range, short- and long-term strength development, for example, from 3 hours to 28 days after application of the cement composition of the present invention may be poor.

As the expander used in the present invention, any of an iron powder expander and a non-metallic expander can be used, but the use of non-metallic calcium sulfaluminate is preferred. The amount of expansion material used is CA100
It is preferably at least 1 part by weight, more preferably at least 5 parts by weight, based on parts by weight. If the amount is less than 1 part by weight, expansion of the kneaded mortar may not be expected.

As the clay mineral (hereinafter, referred to as clay) used in the present invention, a montmorillonite mineral represented by bentonite, a kaolinite mineral, and an illite mineral can be used. Of these, use of bentonite is preferred. The amount of the clay used is preferably 10 to 200 parts by weight, more preferably 50 to 150 parts by weight, based on 100 parts by weight of CA. If it is less than 10 parts by weight, it may be difficult to secure fluidity without separating the material, and if it exceeds 200 parts by weight, not only is it disadvantageous in terms of price, but also a significant decrease in fluidity,
This may cause poor strength development.

In the present invention, a cement admixture containing CA, gypsum, an expansive material, and a clay material is used. The amount of cement admixture used is 1 to 5 parts per 100 parts by weight of cement.
00 parts by weight is preferable, and 5-200 parts by weight is more preferable.
If the amount is less than 1 part by weight, a predetermined strength cannot be obtained, it is not only difficult to secure fluidity without separating the material, but also the cured product may be significantly shrunk. If it exceeds 500 parts by weight, not only is the economical disadvantage due to an increase in the amount of the setting modifier and the like used, but also the fluidity may be significantly reduced.

[0012] 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 these portland cements with pozzolanic substances such as blast furnace slag and fly ash. However, there is no particular limitation as long as the object of the present invention is not hindered. In the present invention, alumina cement can also be used as cement.

The fine aggregate used in the present invention is a fine aggregate specified by JIS and has a maximum particle size of 5 mm or less. The material of the fine aggregate is not particularly limited, and for example, general fine aggregate such as silica sand and lime sand can be used. The amount of fine aggregate used is cement, CA, gypsum,
The amount is preferably 50 to 150 parts by weight based on 100 parts by weight of the total of the expanding material (hereinafter referred to as a binder). If the amount is less than 50 parts by weight, the amount of binder used per unit volume increases, which is not only economically disadvantageous, but also the aggregate does not sufficiently fill the gap of the check valve, and the cement milk is removed from the gap of the check valve. Has been washed away,
Normal operation may not be performed, and if it exceeds 150 parts by weight, it may be difficult to secure fluidity without separating materials.

The amount of water used in the present invention is preferably from 50 to 200%, more preferably from 60 to 100%, in a water / binder ratio (W / P). If it is less than 50%, the desired fluidity may not be obtained, and if it exceeds 200%, the material may be separated. In particular, when the cement composition of the present invention is used as a grout material, the properties are maximized when kneaded at a W / P of 50 to 200%, but external factors such as air temperature and water temperature and the target softness. It is possible to change the water / binder ratio depending on the degree.
When W / P exceeds 200%, not only the material separation resistance is reduced but also the strength may be reduced.

In the present invention, in addition to cement, fine aggregate and cement admixture, a setting regulator can be used to secure the required working time and to improve the initial strength enhancement. is there.

Examples of the setting modifier include chlorides such as calcium chloride, ferric chloride, and aluminum chloride; aluminates such as sodium aluminate and potassium aluminate; carbonates such as sodium carbonate and potassium carbonate; Hydroxides such as sodium and potassium hydroxide, and inorganic salts such as zinc silicofluoride, magnesium silicofluoride, and silicofluoride such as sodium silicofluoride; furthermore, citric acid, gluconic acid, and tartaric acid or calcium salts thereof And the like, and one or more of these can be used. Of these, the combined use of a carbonate and an organic acid is most preferable because a rapid curing reaction is exhibited after the delay. The amount of setting modifier used is 10
It is preferably 5 parts by weight or less based on 0 parts by weight. If it is used in an amount exceeding 5 parts by weight, not only is it economically disadvantageous, but also the hydration reaction of the binder is significantly inhibited, and there is a case where it does not cure at all.

In the present invention, a water reducing agent can be used if necessary. Here, as a water reducing agent,
All water reducing agents used in the general cement field can be used, and the amount used is within the range generally used.

Further, in the present invention, various additives can be used in combination. As additives, for example, fibers such as glass fiber, carbon fiber, and steel fiber, polymer polymer emulsion (latex), colorant (pigment),
One or more selected from the group consisting of an AE agent, a fluidizing agent, a rust inhibitor, an inseparable admixture in water, a thickener, a water retention agent, a waterproofing agent, and an antifreezing agent are used for the purpose of the present invention. It can be used within a range that does not substantially inhibit.

As the mixing device used for kneading the grout material of the present invention, an existing stirring device can be used. For example, a tilting mixer, an omni mixer, a V-type mixer, a Henschel mixer, and a Nauter mixer Etc. can be used. As for the mixing of the materials, the respective materials may be mixed at the time of construction, or some or all of them may be mixed in advance.

Further, when various additives are mixed according to the situation, the amount of these additives is generally determined with respect to the amount of cement, and in the present invention, even if mixed with fine aggregate,
Because there is no separation of fine aggregate and its fluidity can be maintained,
Compared with cement milk, the addition amount of these additives per unit volume can be reduced, and the backflow of the grout material can be prevented in construction using a simple check valve.

[0021]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to experimental examples, but the present invention is not limited to these experimental examples.

Experimental Example 1 A cement admixture was prepared by blending CA, gypsum, an expanding material, and a clay shown in Table 1. For 100 parts by weight of cement, add a cement admixture so that CA becomes 10 parts by weight,
Also, with respect to 100 parts by weight of the binder, the fine aggregate was mixed so as to be 100 parts by weight, and with respect to 100 parts by weight of the binder, 74 parts by weight of water was added and kneaded to prepare a mortar, The fluidity, pot life, compressive strength, bleeding rate, material separation resistance, and expansion amount were measured. The results are also shown in Table 1.

<Materials> Cement: ordinary Portland cement, commercially available fine aggregate: lime sand manufactured by Denki Kagaku Kogyo Co., Ltd., maximum particle size 4.0 mm, FM 2.73 CA: weight ratio of CaO / Al ₂ O ₃ 55/45 Calcium aluminate, amorphous, Blaine value 6,000cm ² / g Gypsum: Commercial type II anhydrous gypsum, Blaine value 4,500cm ² / g Expanding material: Calcium sulfaluminate, Blaine value 6,000cm ² / g Clay : Bentonite, commercial product Setting regulator: Mixture of organic and inorganic acids Water: Tap water

[0024] <Measurement method> Liquidity: initial falling value, the Japanese Society of Civil Engineering standard of J ₁₄ Funnel assay measuring pot life according to: using a continuous dotting type temperature recorder, mortar temperature increases 1 ℃ from Ri kneaded Time to: Compressive strength: Compressive strength 3 hours after kneading of the prepared 4 × 4 × 16 cm specimen bleeding rate: Measured according to the polyethylene method of Japan Society of Civil Engineers Material separation resistance: 3 minutes after kneading The sand was settled on the bottom of the container, and the degree of sedimentation of the sand was determined by touch. The mark 無 し indicates no material separation, the mark 若干 indicates slight material separation, but practically no problem. Expansion: Measured at 7 days of age according to JIS A 6202

[0025]

[Table 1]

As is clear from Table 1, the comparative example without addition of CA has no immediate effect and does not cure in 3 hours. On the other hand, when gypsum is not included, instantaneous setting occurs, and it becomes difficult to secure the pot life. When the amount of gypsum added is increased, the 3-hour compressive strength tends to slightly decrease.

Experimental Example 2 The same procedure as in Experimental Example 1 was carried out except that the clay shown in Table 2 was used for 100 parts by weight of CA, 150 parts by weight of gypsum, and 25 parts by weight of the expansive material. The results are also shown in Table 2.

[0028]

[Table 2]

As is clear from Table 2, when no clay is used, not only the settling of the aggregate occurs, but also bleeding occurs. On the other hand, increasing the amount of clay improves the material separation resistance but makes it difficult to secure fluidity

Experimental Example 3 An experiment was performed in the same manner as in Experimental Example 1 except that the expanding materials shown in Table 3 were used for 100 parts by weight of CA, 150 parts by weight of gypsum, and 100 parts by weight of clay. The results are also shown in Table 3.

[0031]

[Table 3]

As is clear from Table 3, when no expanding material is added, the expansion amount becomes negative. On the other hand, in the example to which the expanding material is added, the compressive strength development property and the material separation resistance are good, and the expansion amount is also positive.

Experimental Example 4 A cement admixture consisting of 100 parts by weight of CA, 150 parts by weight of gypsum, 25 parts by weight of an expanding material, and 100 parts by weight of a clay material was prepared. The procedure was performed in the same manner as in Experimental Example 1 except that the cement admixture shown in Table 3 was mixed with 100 parts by weight of the cement.
The results are also shown in Table 4.

[0034]

[Table 4]

As is evident from Table 4, when no cement admixture is added, not only short-term strength development is obtained but also material separation occurs. On the other hand, cement admixture
When 80 parts by weight were added, the fluidity of the mortar was reduced, the funnel was blocked, and measurement became impossible. When the addition amount of the cement admixture decreases, the material separation resistance decreases,
A decrease in compressive strength was observed. If no further addition is made, the expansion amount becomes negative.

[0036]

The use of the cement admixture of the present invention has the effect of preventing material separation and bleeding while having high fluidity and expansion properties based on an inexpensive material structure. In addition, by using a general setting regulator, a pot life of 30 minutes or more is secured, and a compressive strength of about ² N / mm2 is developed in 3 hours, so some trouble occurs during the construction work In such a case, it is possible to respond to such a situation, and it is also possible to use the apparatus in the next day of night work or in emergency work.

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Claims (3)

[Claims] 1. A cement admixture containing calcium aluminate, gypsum, an expanding material, and a clay mineral. 2. A cement composition comprising a cement, a fine aggregate, and the cement admixture according to claim 1. 3. A grout material comprising the cement composition according to claim 2.