JP2003286064A - Cement composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement composition which has excellent and stable fluidity, high compressive strength and excellent unshrinkable property and can supply a material other than water in a premixed state. <P>SOLUTION: This cement composition contains the cement of high belite content, silica fumes, a cement dispersing agent containing as a principal component a polycarboxylic acid-based macromolecular compound having a polyalkylene glycol chain, a lime-based mixing agent or an organic shrinkage reducing agent, a substance for generating the pressure against the contractile force caused by the hydration reaction of the cement of high belite content and a fine aggregate having ≥3.4 specific gravity and 0.5-1.5% water absorption. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cement composition, and more particularly to a cement composition which can be used as a mortar filler for reinforcing bar joints and the like and which has excellent strength development, fluidity and non-shrinkability.

[0002]

2. Description of the Related Art Conventionally, in order to improve the strength of cement compositions, a method of reducing the water / cement ratio by using a water reducing agent has been taken. However, the water / cement ratio is approximately 3
When it is less than 0% by weight, sufficient fluidity cannot be obtained and workability is deteriorated. Therefore, a grout material composition (Japanese Unexamined Patent Publication No. 09-263438) that has high fluidity even in a low amount of water by preliminarily holding a small amount of water in hydraulic cement and can exhibit high strength of 80 MPa or more in compression strength is proposed. Has been done. In addition, a grout mortar composition that secures a compressive strength of about 100 MPa by using ultrafine powder (silica fume), a high-performance water reducing agent, and a weight aggregate (Japanese Patent Laid-Open No. Hei 0 (1999) -29242).
6-293549 gazette) or early strength cement,
A grout material (Japanese Patent Laid-Open No. 11-49549) that secures a compressive strength of about 100 MPa has been proposed.

However, for example, in the case of filling mortar used for reinforced joints, with the recent increase in size of reinforced concrete structures and improvement of seismic performance, while maintaining a predetermined fluidity, high strength of 120 MPa or more in compressive strength is obtained. It has become desired. Therefore, none of them has sufficient performance. Further, when a high-condensation product of naphthalenesulfonic acid formalin was used as a high-performance water reducing agent, it was difficult to maintain good fluidity for a long time, so that satisfactory workability was not obtained.

Further, a water-reducing agent containing a water-soluble vinyl copolymer having a high water-reducing performance as a main component is used to obtain a compressive strength of 120M.
A technique for producing high-strength concrete of Pa or higher (Japanese Patent Laid-Open No. 06-191918) has also been proposed. However, as in this technique, when an ultrafine powder such as silica fume is added to a cement composition having an extremely low water / binder ratio, the amount of curing shrinkage increases significantly, making it difficult to ensure non-shrinkability. There was a problem of becoming.

[0005]

In view of the above problems, the present invention provides good and stable fluidity, high compressive strength, and
An object of the present invention is to provide a cement composition that has good non-shrinkability and is suitable as a filler for reinforcing bar joints, and that can supply materials other than water in the form of premix.

[0006]

In order to achieve the above object, the cement composition of the present invention comprises a high belite cement and a fine bone having a specific gravity of 3.4 or more and a water absorption rate of 0.5 to 1.5%. A cement composition mainly comprising a cement material, wherein the cement composition mixed with water has a flow value of 200 mm or more (JI
It is possible to hold for 60 minutes or more after kneading a static flow using a flow cone specified by SR5201 for 60 minutes or more, and the hydrated cured product of the mixed ream has a compressive strength of 28 days old (JIS.
R5201) is 120 MPa or more, and the coefficient of expansion up to 7 days old (JSCE-F533) is 0 to 1%.
It can be

As one of the more preferable forms of the cement composition of the present invention, a high belite type cement, a high belite type cement, silica fume, and a polycarboxylic acid type high molecular compound having a polyalkylene glycol chain are main components. Cement dispersant, a lime-based admixture, a substance that generates a pressure against the shrinkage force due to the hydration reaction of the high belite-based cement, a specific gravity of 3.4 or more, and a water absorption rate of 0. It is characterized by containing 5 to 1.5% of fine aggregate.

As another form of the cement composition of the present invention, high belite cement, silica fume, and a cement dispersant containing a polycarboxylic acid polymer having a polyalkylene glycol chain as a main component, An organic shrinkage-reducing agent, a substance that generates a pressure against the shrinkage force caused by the hydration reaction of water with the high belite cement, a specific gravity of 3.4 or more, and a water absorption rate of 0.5 to 1. Some contain 5% fine aggregate.

Further, as another mode of the cement composition of the present invention, a high belite cement, silica fume, and a cement dispersant containing a polycarboxylic acid polymer having a polyalkylene glycol chain as a main component, A lime-based admixture, an organic shrinkage-reducing agent, a substance that generates a pressure against the shrinkage force resulting from the hydration reaction of the high belite cement and water, a specific gravity of 3.4 or more, and a water absorption rate of Some include 0.5 to 1.5% fine aggregate.

Each of the above-mentioned cement compositions according to the present invention is suitable as a filler for reinforcing bar joints.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION 1. Performance [Flowability] The cement composition of the present invention is required to maintain a flow value of 200 mm or more after kneading with water for 60 minutes or more after kneading. In filling the reinforcing bar joint, which is the main purpose of the cement composition of the present invention, it is necessary to completely fill the narrow gap between the reinforcing bar and the joint with the filling mortar, so that the filling mortar (cement composition) has a predetermined content. Flowability (flow value of 200 mm or more) is required. Further, since the filling work is usually performed for a plurality of reinforcing bar joints, a predetermined amount of the filled mortar (cement composition) is manufactured, and then a predetermined fluidity is maintained until the filling work for the plurality of reinforcing bar joints is completed. (Flow value of 200 mm or more)
It is necessary to hold the above, and if the fluidity holding time of 60 minutes or more after kneading can be secured, the filling operation can be performed without any trouble.

[Strength] In the cement composition of the present invention, it is essential that the compressive strength of the hydrated cured product at 28 days of age is 120 MPa or more. In recent years, reinforced concrete structures have been improved in durability (seismic resistance) and weight reduction (reduction of the amount of reinforcing bars) by adopting high-strength reinforcing bars, etc. This is a very important issue. In order to further increase the durability and weight of reinforced concrete structures in the future, compressive strength of 120MP
A filled mortar having a high strength of a or higher is desired (compressive strength of conventional filled mortar is about 60 MPa, and maximum is about 100 MPa).

[No shrinkage] The cement composition of the present invention comprises
It is indispensable that the coefficient of expansion up to the age of 7 days is 0 to 1%. In a reinforcing bar joint, it is not preferable that a void is formed between the reinforcing bar and the filling mortar or between the joint and the filling mortar because the connecting strength is reduced. Even if the filling state is good, the filling mortar needs to be non-shrinking (expansion rate 0% or more) because when the filling mortar shrinks in the hydration hardening process, voids are eventually generated and the connection strength is reduced. is there. Furthermore,
It is preferable that the filling mortar has some expandability, but excessive expansion can cause a decrease in strength.
The expansion coefficient is preferably about 1% or less.

2. Materials Used In the present invention, high belite cement is contained as an essential component. High belite cement refers to a cement in which the content of alite, which is the main component of ordinary Portland cement, is reduced and the content of belite is higher than that of medium heat Portland cement. Belite (2CaO ・ SiO ₂ ) as high belite cement
Those containing 40% by weight or more can be preferably used. It is particularly preferable that the belite content is 50% by weight or more and the Blaine specific surface area is 4500 cm ² / g or less.
This is because it is suitable for securing good fluidity for a long time when the water / binder ratio is low.

In the present invention, it is preferable to use silica fume in order to ensure good fluidity at a low water / binder ratio. Among them, silica fume has an average particle diameter of 0.20 μm or less and a carbon content of 1.
Those less than 5% by weight can be preferably used. When the average particle size is 0.20 μm or less, it becomes easy to secure good fluidity even when the water / binder ratio is extremely low (generally 24% or less). When the carbon content is less than 1.5% by weight,
Even with such a low water / binder ratio, it becomes easy to stably secure good fluidity for a long time.

Further, in order to stably obtain good fluidity, it is preferable to use a cement dispersant, and among them, those containing a polycarboxylic acid type polymer compound having a polyalkylene glycol chain as a main component are more preferable. . Cement dispersants containing polycarboxylic acid polymer as the main component maintain fluidization performance and fluidity compared to dispersants containing naphthalene sulfonic acid formalin high condensation products and melamine sulfonic acid formalin high condensation products as main components. This is because the property is high.

The cement dispersant containing the polycarboxylic acid polymer having a polyalkylene glycol chain as a main component can also be used in the form of powder by dry-dispersing the dispersant solution. As such a polymer compound, a group -COOM (M represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium or an organic amine)
And a (meth) acrylic acid-based copolymer having a polyalkylene glycol chain, or a polyalkylene glycol alkenyl ether-maleic anhydride-based copolymer (however,
(Excluding polyvalent metal salts) and the like are preferable. The polyalkylene glycol chain, polyalkylene glycol chain having 2 to 4 carbon atoms, more preferably, -O (CH ₂ C
H (R ^a ) O) _b −. Here, R ^a represents a hydrogen atom or a methyl group, and b is preferably 2 to 200. In addition, it is preferable to add a reducing inorganic compound such as a nitrite and a reducing organic compound such as an amine compound to the above liquid before drying and powdering. The addition amount (solid content) of each of these is preferably 0.01 to 2.5% by weight based on the solid content of the polycarboxylic acid polymer compound. Further, it is preferable that the above liquid is adjusted to pH 7-9. The method of dry powdering is not particularly limited, but it is preferably carried out while kneading and stirring.
(The dispersant for powdery hydraulic compositions described in JP 2001-002788 A can be used as the cement dispersant of the present invention). Thus, by using the powdered cement dispersant, it is possible to obtain an easy-to-handle cement composition that can supply materials other than water in the form of a premix.

The cement composition according to the present invention preferably contains either a lime-based admixture or an organic shrinkage-reducing agent, or both in order to obtain non-shrinkability. The lime-based admixture can be used for suppressing self-shrinkage and improving non-shrinkability, and for forming a solid and high-strength hardened body. As the lime-based admixture, a lime-based expansive material generally used for mortar concrete,
Although a lime-based admixture used as a hardening accelerator when producing a concrete product can be used, a mixed pulverized product of a clinker containing CaO crystals and gypsum is preferable. The total amount of CaO in the clinker is 50-9
Those containing 2% by weight are preferable. Also, the clinker
The main mineral composition is 3CaO ・ SiO ₂ -2CaO ・
SiO ₂ -CaO- gap quality, 3CaO · SiO ₂ -CaO
- gaps quality, those containing one or more selected from the group consisting of 2CaO · SiO ₂ -CaO- gap cytoplasm preferred. As the gypsum, any of anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum can be used. The mixing ratio of clinker and gypsum is preferably 5 to 50 parts by weight of gypsum with respect to 100 parts by weight of clinker (JP 2001-3974 A).
8).

The organic shrinkage-reducing agent can be used for suppressing self-shrinkage and improving non-shrinkability, and for forming a solid and high-strength cured product. Examples of the organic shrinkage reducing component constituting the organic shrinkage reducing agent include those having an alkylene oxide polymer represented by the following formula (1) in the skeleton of the chemical structure. R ¹ O (AO) _n R ² (1) In the formula, R ¹ and R ² are each independently a hydrogen group, an alkyl group, a phenyl group, a cycloalkyl group, or the like, and A is a carbon number. 2 to 3 are one alkylene group or two random or block-polymerized alkylene groups, and n is 2
Is an integer of -20. In particular, an organic shrinkage reducing agent in which R ² is a hydrogen group can be preferably used (Japanese Patent Publication No. 59-3430).
(Including those described in the publication).

As the organic shrinkage-reducing agent, an oil-absorbing inorganic or organic powdery material is preliminarily impregnated with, for example, a liquid organic shrinkage-reducing agent component of the above-mentioned component to obtain a powdery form. A premixed product that is easy to handle can be obtained by using the material. Fibrous magnesium oxide or the like can be used as the inorganic powder, and phenol resin or the like can be used as the organic powder (Japanese Patent Laid-Open No. 2-16).
(Including those described in Japanese Patent No. 4754).

The organic shrinkage reducing agent is generally used to reduce the dry shrinkage of the hardened cement.
Drying shrinkage of a hardened cement material generally causes tensile stress in the capillary tube of the hardened material due to the formation of a meniscus by drying,
It is believed that this causes elastic volume contraction of the cured body. The organic shrinkage-reducing agent has the effect of lowering the surface tension of water in the voids of the cured body, which reduces the tensile stress in the capillaries and reduces the amount of shrinkage. On the other hand, the mechanism of self-shrinkage is considered to cause tensile stress in the capillaries of the cured product to shrink the volume due to self-drying accompanying the progress of hydration. It is also effective in reducing self-shrinkage.

The cement composition according to the present invention contains a substance that generates a pressure against the shrinkage force due to the hydration reaction of high belite cement in order to ensure non-shrinkage at the initial age. It is preferable. In the present invention, as described above, shrinkage is reduced by using a lime-based admixture, an organic shrinkage-reducing agent, or the like, but this alone cannot secure sufficient non-shrinkage especially at the initial age. . Therefore, the coefficient of expansion up to 7 days of age (JSCE-F53
The substance is used to adjust 3) to 0 to 1%. When the substance is added to the cement composition, the gas generated inside the cement composition is trapped inside the cement composition as the hardening progresses during hydration. As the amount of this gas increases, it becomes an internal pressure, which acts as a counter force against the shrinkage phenomenon due to the hydration reaction of high belite cement, and it is possible to suppress the shrinkage more effectively, and even at the initial age A high non-shrinkage property can be secured. As such a substance, for example, a foaming agent or the like can be used, and it is preferably obtained by heating a metal powder such as aluminum powder or a carbon-based compound such as fluid coke which is a by-product of petrochemistry. Granular material (Japanese Patent Publication No. 60-4150)
Gazette) can be used. In this specification,
In order to simplify the description, the substance may be referred to as a foaming agent or the like.

Here, the kneaded product of the cement composition and water can hold a flow value of 200 mm or more for 60 minutes or more after kneading, and the hydrated cured product of the kneaded product has a material age of 28 days. If it is possible to obtain a high compressive strength of 120 MPa or more and a good non-shrinkage with an expansion coefficient of 0 to 1% by the age of 7 days, it is possible to secure the non-shrinkability of the cement composition of the present invention. The substances involved are not limited to the lime-based admixtures, organic shrinkage-reducing agents, and substances (foaming agents, etc.) that generate a pressure against the shrinkage force caused by the hydration reaction of high belite cement described above. , Other mixed materials can be alternatively compounded. By ensuring the non-shrinkage property, when used as a filler for a reinforcing bar joint, for example, it is possible to eliminate the risk of reduction in the connection strength due to shrinkage.

The cement composition of the present invention contains a specific fine aggregate as an essential component. That is, as a fine aggregate, a kneaded product of a cement composition and water can hold a flow value of 200 mm or more for 60 minutes or more after kneading,
In addition, a hydrated cured product of the kneaded product is used, which is likely to have properties such that it has a compressive strength of 120 MPa or more (age 28 days). Such fine aggregate has a specific gravity of 3.4 or more, preferably 3.7 to 7, and a water absorption rate of 0.5 to 1.5.
%, Preferably 0.6 to 1.4% can be suitably used. By setting the specific gravity to 3.4 or more, stable fluidity with time can be obtained and high compressive strength can be obtained even when the water / binder ratio is low. Further, by setting the water absorption rate to 1.5% or less, it is possible to obtain stable fluidity with time even when the water / binder ratio is low. On the other hand, by setting the water absorption rate to 0.5 or more,
Strength development can be improved. Here, the water absorption rate is the amount of water absorbed by the aggregate (the amount of water contained in the surface-dried aggregate)
Is divided by the amount of bone material in an absolutely dry state, and is a value expressed as a percentage. The test method for water absorption rate is JIS A 1109.
The test was carried out according to "Testing method for specific gravity and water absorption of fine aggregate".
Any fine aggregate can be used as long as it satisfies the specific gravity and the water absorption. In general, fine aggregates such as river sand, sea sand, land sand, crushed sand, silica sand, magnetite sand, iron sand and metal aggregates are often out of the above specific gravity and water absorption rates by themselves. It is possible to suitably use the mixed sand prepared by using a plurality of the above to adjust the specific gravity and the water absorption rate. Further, in order to obtain a good filling property when the cement composition of the present invention is used as a filler for a reinforcing bar joint, it is preferable that the fine aggregate has a maximum particle size of less than 3 mm.

The cement composition of the present invention requires components other than the above components, such as a thickener, a defoaming agent and a rust preventive agent, as long as the characteristics shown in claim 1 are secured. It may be included as appropriate.

3. Regarding the compounding ratios thereof in the preferred materials, an example of the compounding ratios will be shown below. Therefore, as a preferred system for achieving the object, high belite cement, silica fume, fine aggregate and cement dispersant, and further lime system are used. Admixtures, organic shrinkage reducing agents, and foaming agents are taken up, and their compounding ratios are shown. (1) Mixing ratio of high belite cement and silica fume In the present invention, the mixing ratio of the high belite cement and silica fume is cement / weight ratio.
Silica fume is preferably mixed in a ratio of 90/10 to 98/2. With this mixing ratio, a kneaded product having a relatively low viscosity can be obtained even when the water binder ratio is extremely low (generally 26% or less). Good fluidity (200 m
A flow value of m or more "a static flow using a flow cone defined in JIS R 5201" is maintained for 60 minutes or more) and good strength development (compressive strength 28 days old "JIS R 5
201 "is 120 MPa or more). A more preferable blending ratio is high belite cement / silica fume = 92/8 to 97/3 by weight.

(2) Mixing ratio of cement dispersant When using a dispersant containing a polycarboxylic acid polymer having a polyalkylene glycol chain as a main component, the mixing ratio is such that a high belite cement is used. 0.1 per 100 parts by weight of silica fume and silica fume
˜2 parts by weight, preferably 0.5 to 1.5 parts by weight.
By adjusting the amount of this dispersant to be 0.1 parts by weight or more,
Even if the water binder ratio is extremely low (approximately 26% or less), good fluidity can be secured. Further, when the amount is 2 parts by weight or less, good fluidity can be secured without causing delay in curing or the like.

(3) Mixing ratio of lime-based admixture and organic shrinkage-reducing agent The mixing ratio of the lime-based admixture is usually 1 to 10 per 100 parts by weight of high belite cement and silica fume.
Parts by weight, preferably 3 to 8 parts by weight. By using lime-based admixture in an amount of 1 part by weight or more, the cement composition containing silica fume can effectively reduce the self-shrinkage that becomes noticeable when the water binder ratio is low. You can Further, when the content is 10 parts by weight or less, the risk of deterioration of fluidity and strength reduction due to excessive expansion can be extremely reduced.

When the organic shrinkage reducing agent is used, the compounding ratio is usually 0.5 to 5 with respect to the total amount of 100 parts by weight of high belite cement and silica fume as the amount of active ingredient.
Parts by weight, preferably 1 to 3 parts by weight. By adjusting the amount of the organic shrinkage-reducing agent to be 0.5 parts by weight or more, it is possible to effectively reduce the self-shrinkage, which becomes noticeable when the water binder ratio is low, in the cement composition containing silica fume. it can. Further, when the amount is 5 parts by weight or less, the risk of strength reduction due to retardation of setting can be extremely reduced.

The lime-based admixture and the organic shrinkage-reducing agent can also be used in combination. In this case, the mixing ratio of each is not particularly limited, and each can be added within the above range, but used alone. The amount can be decreased depending on the ratio of combined use as compared with the case of mixing.

(4) Blending Ratio of Foaming Agent, etc. The blending ratio of a material (foaming agent, etc.) that generates a pressure against the shrinkage force caused by the hydration reaction of high belite cement is metal powder. In the case of, it is 0.0 for 100 parts by weight of high belite cement and silica fume.
001 to 0.002 parts by weight is preferable, and 0.1 to 5 parts by weight is preferable in the case of a granular material obtained by heating a carbon-based compound such as fluid coke. Within this range, the cement composition of the combination of the materials of this example can ensure good non-shrinkability without causing a decrease in strength due to excessive expansion. Further, the foaming agent and the like can be used in combination of two or more kinds, and in that case, the mixing ratio of each is not particularly limited, and each can be added within the above range, but the mixing ratio when used alone. Compared with the above, it can be decreased according to the ratio of combined use.

(5) Mixing Ratio of Fine Aggregate The mixing ratio of fine aggregate is preferably 40 to 120 parts by weight based on 100 parts by weight of high belite cement and silica fume. Within this range, the cement composition can be easily kneaded even when the amount of water is reduced, and the increase in viscosity after kneading is small, so good fluidity can be secured. A more preferable mixing ratio is 60 to 100 parts by weight.

In the present invention, in order to achieve both high compressive strength and good and stable fluidity, the amount of water added is, for example, 100 parts by weight of high belite cement and silica fume in total in the above-mentioned formulation examples. 16-24
Weight% is preferable, and 18 to 22 weight% is more preferable.

4. Manufacturing Method and Others The cement composition of the present invention is, for example, prepared by premixing the above-mentioned materials in a factory by a conventional method and usually supplied to a construction site in a form such as bagging, and is mixed at the construction site with a mixer. Is used by kneading with water. The kneading method is not particularly limited. The device used for kneading is not particularly limited, and a conventional mixer such as a hand mixer, a pan mixer, a biaxial kneading mixer, or a tilting cylinder mixer can be used. The use of the cement composition of the present invention is also not particularly limited, but it is preferably used as a filler for reinforcing bar joints. The method of use is the same as the conventional mortar filler for reinforcing bar joints and is not particularly limited.

[0035]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The materials used in Examples and Comparative Examples are as follows.

[Materials Used] (1) Cement Table 1 shows the chemical components and specific surface areas of the cements used in Examples and Comparative Examples.

[0037]

[Table 1]

(2) Silica fume Silica fume having an average particle size of 0.14 μm and a carbon content of 0.50% was used in Examples and Comparative Examples.

(3) Cement dispersant (A) Cement dispersant in powder form containing polycarboxylic acid type polymer compound as a main component (abbreviation: A) 54 mol% sodium methacrylate, 7 mol% sodium methallyl sulfonate, 8 mol% methyl acrylate,
Aqueous solution containing a polymer compound having a molecular weight of 11900 and obtained by polymerizing 16 mol% of methoxy poly (n = 40) ethylene glycol methacrylate and 15 mol% of methoxy poly (n = 23) ethylene glycol methacrylate as a main component and having a solid content concentration of 45% For each 800 g, 10% by weight concentration of sodium hydroxide aqueous solution 75.
2 g was added and the mixture was stirred at room temperature for about 3 minutes. Then, 0.5 part by weight of sodium sulfite and triethanolamine were added to 100 parts by weight of the solid content of the polymer compound, and the mixture was stirred for 3 minutes. This was placed in a kneader-type kneading stirrer having a processing volume of 1 L, and concentrated and dried while kneading at a temperature of 90 ° C. and a reduced pressure of 30 torr. The obtained powder and granules were pulverized with a pulverizer and classified to produce a powder (A) having a particle diameter of 50 to 500 μm. The water content of the powder was 2.1% by weight.

(B) Conventional powdery cement dispersant (abbreviation: B) In the comparative example, a high-condensation product of formalin naphthalene sulfonate (Mighty 100 manufactured by Kao Corporation) was used.

(4) Lime-based admixture Table 2 shows the main chemical components and specific surface areas of the lime-based admixtures used in Examples and Comparative Examples.

[0042]

[Table 2]

(5) Organic shrinkage reducing agent As an organic shrinkage reducing agent, trade name: Tetraguard PW
(Powdered organic shrinkage reducing agent with 60% active ingredient, main component:
Oxyalkylene alkyl ether) (manufactured by Taiheiyo Material Co., Ltd.) (abbreviation: TG) was used.

(6) Product name: PERMAN as a substance that generates a pressure against the shrinking force caused by the hydration reaction of high-belite cement such as a foaming agent
ENT LIFE AGGREGATE (carbon-based foaming agent whose main component is a granular material obtained by heat-treating a carbon-based compound) (INTERNAT
IONAL CONSTRUCTION PRODUCTS RESEARCH INC.) (Abbreviation: PL) was used.

(7) Fine aggregates Table 3 shows the average particle size, specific gravity and water absorption of the fine aggregates used in the comparative examples. The fine aggregate of mixed sand obtained by mixing these fine aggregates was used in Examples and Comparative Examples. Table 4 shows the average particle size, specific gravity and water absorption of these.

[0046]

[Table 3]

[0047]

[Table 4]

[Preparation Method of Cement Composition] Each of the above materials is premixed in advance so that the compounding amount shown in Table 5 is obtained, and a predetermined amount of water is added to 100 parts by weight of the base material. 1100 rpm) was kneaded for 3 minutes to prepare a cement composition.

[0049]

[Table 5]

[Test Method] Flowability: Using a flow cone specified in "JIS R 5201 (Physical test method for cement)", a static flow without drop motion of the table was used from immediately after kneading until after 60 minutes. It was measured. The measurement results are shown in Table 6. Compressive strength: According to "JIS R 5201 (Physical test method for cement)", the compressive strength at 28 days of age was measured. The measurement results are shown in Table 6. Expansion coefficient: The expansion coefficient up to 7 days old was measured according to the Japan Society of Civil Engineers standard “PC grout test method (container method) (JSCE-F533)”. The measurement results are shown in Table 6.

[0051]

[Table 6]

As shown in Table 6, Examples 1 to 13 have 2
A flow value of 00 mm or more was maintained for 60 minutes or more after kneading, and stable high fluidity could be obtained. Also, age 28
The daily compressive strength was 120 MPa or more, and high strength could be obtained. Furthermore, the coefficient of expansion until the age of 7 days is 0
It was 0.5%, and good non-shrinkability could be obtained.

On the other hand, Comparative Examples 14, 15, 19 and 21 using the fine aggregate having a specific gravity of 3.3 or less have a flow value of 180 mm or less after 60 minutes after kneading, and can stably obtain high fluidity. Moreover, the compression strength was less than 120, and high strength could not be obtained. Further, Comparative Examples 16 to 18 and 20 using the fine aggregate having a specific gravity of 3.4 or more but a water absorption rate of less than 0.5 have a flow value of 210 mm or more after 60 minutes after kneading and are stable. However, the compressive strength was less than 120, and high strength could not be obtained.

Comparative Example 2 in which no foaming agent or the like was used
In No. 2, the expansion rate was −0.5% or less, and no shrinkage was obtained. Further, in Comparative Example 23 in which neither the lime-based admixture nor the organic shrinkage reducing agent was used, the expansion rate was 0% or less and no shrinkage was obtained, and the compressive strength was also less than 120, and high strength was also obtained. I couldn't do it. Furthermore, Comparative Example 24 in which a cement dispersant containing a polycarboxylic acid polymer as a main component was not used, Comparative Example 25 in which silica fume was not used, and Comparative Example 26 in which high belite cement was not used. Has a flow value of 140 after 60 minutes of kneading.
It was less than mm, and stable high fluidity could not be obtained.

[0055]

As described above, according to the present invention,
It is possible to provide a cement composition that has good fluidity, high compressive strength, and good non-shrinkability, and that can also supply materials other than water in the form of a premix.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C04B 24/32 C04B 24/32 A 24/36 24/36 // C04B 103: 32 103: 32 103: 60 103: 60 111: 20 111: 20 111: 34 111: 34 (72) Inventor Katsuya Kono, 2-4-2 Daisaku, Sakura City, Chiba Prefecture, Central Research Laboratory, Taiheiyo Semento Co., Ltd. (72) Masaki Ishimori Sakura, Chiba Prefecture Ichiro Daisaku 2-4-2 Taiheiyo Cement Co., Ltd. Central Research Laboratory F-term (reference) 4G012 MA00 MB23 PA15 PB03 PB04 PB11 PB31 PB32 PB33 PB36 PC02 PC03 PC09 PC11 PC12

Claims (5)

[Claims] 1. A high belite cement and a specific gravity of 3.4.
A cement composition mainly composed of a fine aggregate having a water absorption rate of 0.5 to 1.5% as described above, wherein a kneaded product of the cement composition with water has a flow value of 200 mm or more after kneading 60 The hydrated cured product of the mixed compound has a compressive strength of 28 days old of 120 MPa or more and an expansion rate of 0 to 1% by 7 days old. And a cement composition. 2. A high belite cement, a silica fume, a cement dispersant containing a polycarboxylic acid polymer having a polyalkylene glycol chain as a main component, a lime admixture, and the high belite cement. And a fine aggregate having a specific gravity of 3.4 or more and a water absorption rate of 0.5 to 1.5%. Cement composition. 3. A high belite cement, a silica fume, a cement dispersant containing a polycarboxylic acid polymer having a polyalkylene glycol chain as a main component, an organic shrinkage reducing agent, and the high belite cement. A substance that generates pressure to counter the contraction force caused by the hydration reaction of cement, and a specific gravity of 3.4 or more and a water absorption rate of 0.5 to 1.5%
And a fine aggregate which is a cement composition. 4. A high belite cement, a silica fume, a cement dispersant containing a polycarboxylic acid polymer having a polyalkylene glycol chain as a main component, a lime admixture, and an organic shrinkage reducing agent. A substance that generates a pressure that opposes the shrinkage force resulting from the hydration reaction of the high belite cement, and a fine aggregate that has a specific gravity of 3.4 or more and a water absorption rate of 0.5 to 1.5% A cement composition comprising: 5. The cement composition according to claim 1, wherein the cement composition is used as a filler for a reinforcing bar joint.