JP3162605B2 - Early strength concrete composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an early-strength concrete composition. BACKGROUND ART Early-strength concrete compositions have been used in order to achieve early strength in the obtained cured product to shorten the construction period and save labor in construction. Such an early-strength concrete composition is prepared by using early-strength Portland cement as cement, and further using water, fine aggregate, coarse aggregate, and a cement dispersant. The present invention reduces the deterioration of the fluidity of the prepared concrete composition with time, and at the same time, shows a cured product obtained from the concrete composition to exhibit a sufficient early strength, and also has a resistance to cracking due to drying shrinkage (hereinafter, referred to as “hardening property”). (Referred to as crack resistance).

[0002]

2. Description of the Related Art Conventionally, as a high-strength concrete composition, a high-strength Portland cement is used as a cement, as described above, and further prepared using water, fine aggregate, coarse aggregate and a cement dispersant. Have been. In this case, as the cement dispersant, various water-soluble vinyl copolymers, especially (meth) acrylate and methallyl, are used as in the case of preparing a normal concrete composition using ordinary Portland cement as cement. A water-soluble vinyl copolymer obtained from four kinds of copolymer components of a sulfonate, methyl (meth) acrylate and methoxypolyethoxyethyl methacrylate has been used (Japanese Patent Publication No.
-11057, JP-A-4-209613). However,
Using early-strength Portland cement as cement, and in the preparation of a highly water-reduced early-strength concrete composition, as in the case of preparing a normal concrete composition,
When a water-soluble vinyl copolymer as described above is used as a cement dispersant, the fluidity of the prepared early-strength concrete composition is greatly reduced with time, and the early strength of the obtained cured product is insufficiently expressed, Moreover, there is a drawback that the crack resistance is low.

[0003]

The problem to be solved by the present invention is that the conventional high-strength concrete composition suffers from a large decrease in the fluidity of the concrete composition with time and the early strength of the obtained cured product. It is insufficient in expression and low in crack resistance.

[0004]

Means for Solving the Problems Thus, the present inventors have
As a result of research to solve the above problems, using early strength Portland cement as cement, water, fine aggregate,
In the early-strength concrete composition prepared using the coarse aggregate and the cement dispersant, the water / cement ratio, the unit water amount, the unit amount of the fine aggregate, and the unit amount of the coarse aggregate are respectively set within predetermined ranges, and As a dispersant, a specific water-soluble vinyl copolymer obtained from four copolymer components containing phenoxypolyethoxyethyl methacrylate as one copolymer component is used. Was found to be correct and suitable.

That is, the present invention provides an early-strength concrete composition prepared by using an early-strength Portland cement as a cement, and further using water, fine aggregate, coarse aggregate and a cement dispersant, and having a water / cement ratio of 30 to 30. 65%, unit water amount is 140-185 kg / m ³ , unit amount of fine aggregate is 700
１1200 kg / m ³ and the unit amount of coarse aggregate is 800-12
00 kg / m ³ and early strength Portland cement 1
0.1 to 0.1 parts by weight of the following cement dispersant
The present invention relates to an early-strength concrete composition characterized by being used in a proportion of 2.0 parts by weight.

Cement dispersant: a structural unit A represented by the following formula 1, a structural unit B represented by the following formula 2, a structural unit C represented by the following formula 3, and a structural unit D represented by the following formula 4 Wherein the structural unit A is 45 to 65 mol%, the structural unit B is 2 to 15 mol%, and the structural unit C is 5 to 20 mol% in all the structural units. A water-soluble vinyl copolymer in which the unit D accounts for 10 to 40 mol% and the number average molecular weight is 2,000 to 20,000.

[0007]

(Equation 1)

(Equation 2)

(Equation 3)

(Equation 4)

(In the formulas 1 to 4, R ¹ , R ² : H or CH ₃ R ³ : phenyl group M ¹ , M ² : a cation group selected from alkali metals, alkaline earth metals and organic amines m: 5 (Integer of ~ 45)

The early-strength concrete composition of the present invention uses an early-strength Portland cement as cement, and further comprises water,
It was prepared using fine aggregate, coarse aggregate and a cement dispersant. In such an early-strength concrete composition, in the present invention, the water / cement ratio is set to 30 to 65%.
It is preferably set to 0 to 60%. In addition, the unit water volume is 140
To 185 kg / m ³ , preferably 150 to 180 kg / m ³ . Further, the unit amount of fine aggregate is 700 to 120.
And 0 kg / m ^3, but is preferably a 750~1100kg / m ^3. Then, the unit amount of the coarse aggregate is set to 800 to 1200.
and kg / m ^3, but is preferably a 850~1150kg / m ^3.

The cement used in the present invention is JIS-R5
It is an early-strength Portland cement conforming to No. 210. The type of fine aggregate used in the present invention is not particularly limited, and any of them is a known river sand, sea sand, mountain sand, crushed sand and the like. Further, the coarse aggregate used in the present invention does not particularly limit the kind thereof, and any of the known river gravel,
Crushed stone, lightweight aggregate, etc.

The cement dispersant used in the present invention comprises the structural units A to D represented by the above formulas (1) to (4). These structural units A to D are formed by copolymerizing the corresponding vinyl monomers.

The vinyl monomer which forms the structural unit A represented by the formula 1 includes: 1) an alkali metal salt, an alkaline earth metal salt and an organic amine salt of methacrylic acid;
2) There are alkali metal salts, alkaline earth metal salts and organic amine salts of acrylic acid. Of these, alkali metal salts of methacrylic acid such as sodium and potassium are preferred.

The vinyl monomer which forms the structural unit B represented by the formula 2 includes alkali metal salts, alkaline earth metal salts and organic amine salts of methallyl sulfonic acid. Among them, alkali metal salts of methallylsulfonic acid such as sodium and potassium are preferable.

The vinyl monomer which forms the structural unit C represented by the formula 3 includes methyl acrylate and methyl methacrylate.

Examples of the vinyl monomer which forms the structural unit D represented by the formula 4 include phenoxypolyethoxyethyl methacrylate in which the number of repeating oxyethylene units is 5 to 45. Among them, phenoxypolyethoxyethyl methacrylate having a repeating number of oxyethylene units of 15 to 40 is preferable.

The cement dispersant of the present invention is a water-soluble vinyl copolymer composed of the constitutional units A to D as described above.
65 mol%, preferably 50 to 65 mol%, structural unit B
Is 2 to 15 mol%, preferably 3 to 15 mol%, structural unit C is 5 to 20 mol%, preferably 7 to 20 mol%, and structural unit D is 10 to 40 mol%, preferably 15 to 35 mol%. Of a water-soluble vinyl copolymer.

According to the present invention, among the structural units A to D constituting the water-soluble vinyl copolymer, the structural unit D having a polyoxyethylene chain having a phenyl group at the terminal and the structural ratio thereof are particularly important. is there. In the early-strength concrete composition of the present invention, a specific amount of the above-mentioned specific water-soluble vinyl copolymer having the structural unit D at a predetermined ratio is used as a cement dispersant in the early-strength Portland cement.
The decrease in fluidity over time is reduced, and at the same time, a cured product obtained exhibits sufficient early strength and, at the same time, increases crack resistance.

The present invention does not particularly limit the method of synthesizing the water-soluble vinyl copolymer used as a cement dispersant.
A method such as that described in Japanese Patent No. 750 can be applied. For example, it can be obtained by radical copolymerization of each of the above-mentioned vinyl monomers forming each structural unit in an aqueous solution so as to have a predetermined copolymerization ratio in the presence of a radical initiator. The water-soluble vinyl copolymer thus obtained has a number average molecular weight of 2,000 to 20,000 (GPC
Method, Pullulan conversion), but 3000 to
It is preferably in the range of 15,000.

In the present invention, the amount of the water-soluble vinyl copolymer used as a cement dispersing agent is 0.1 to 0.1 parts by weight in terms of solid content with respect to 100 parts by weight of fast-strength Portland cement.
2.0 parts by weight, but preferably 0.5 to 1.5 parts by weight. The water-soluble vinyl copolymer can be added together with the mixing water when mixing the concrete composition.

The early-strength concrete composition of the present invention comprises the above-mentioned early-strength Portland cement, water, fine aggregate, coarse aggregate and a cement dispersant as essential components, but optionally other agents. Can also be used in combination. Such other agents include air entrainers, defoamers, setting accelerators, setting retarders, rust inhibitors, preservatives, waterproofing agents, and the like.

Hereinafter, examples and the like will be described in order to make the constitution and curing of the present invention more specific, but the present invention is not limited to these examples. In the following examples and the like, parts mean parts by weight, and% means% by weight excluding the amount of air.

[0022]

【Example】

Test Category 1 (Synthesis of water-soluble vinyl copolymer as cement dispersant)-Synthesis of water-soluble vinyl copolymer P-1 100 parts (1.16 mol) of methacrylic acid, 40 parts of sodium methallyl sulfonate (0 .25 mol), 25 parts (0.29 mol) of methyl acrylate, phenoxypolyethoxyethyl (repeating number of oxyethylene units is 15,
(Hereinafter referred to as n = 15) 400 parts of methacrylate (0.4
9 mol) and 750 parts of water were charged into a reaction vessel, and 155 parts of a 30% aqueous solution of sodium hydroxide was added to neutralize the mixture and uniformly dissolved, and then the atmosphere was replaced with nitrogen. The temperature of the reaction system was maintained at 60 ° C.
The polymerization was started by charging 75 parts of an aqueous solution (%), and the polymerization reaction was continued for 6 hours to complete the polymerization. Thereafter, 5 parts of a 30% aqueous sodium hydroxide solution was added to neutralize the acidic decomposition product to neutralize the product, thereby obtaining a product. A part of the obtained product is concentrated by an evaporator, precipitated and purified in a mixed solvent of acetone / isopropanol and dried, and the water-soluble vinyl copolymer P
-1 was obtained. UV absorption of water-soluble vinyl copolymer P-1,
When analyzed by NMR measurement, pyrolysis gas chromatography, elemental analysis, titration, etc., the carboxyl number 110,
The sulfur content was 1.2%, and the copolymerization ratio of each vinyl monomer corresponding to the structural units A to D was sodium methacrylate / sodium methallylsulfonate / methyl acrylate / phenoxypolyethoxyethyl (n = 15). ) Methacrylate = 51/10/13/26 (molar ratio) and number average molecular weight 4,800 (GPC method, in terms of pullulan, the same applies hereinafter).

Synthesis of water-soluble vinyl copolymers P-2 to P-5 and R-1 to R-13 Similarly to the water-soluble vinyl copolymer P-1, the water-soluble vinyl copolymers shown in Table 1 were used. Combined P-2 to P-5 and R-1 to R-
13 was obtained.

[0024]

[Table 1]

In Table 1, A-1: sodium methacrylate A-2: sodium acrylate B-1: sodium methallylsulfonate C-1: methyl acrylate D-1: phenoxypolyethoxyethyl (n = 15) methacrylate D-2: Phenoxypolyethoxyethyl (n = 25) methacrylate D-3: Phenoxypolyethoxyethyl (n = 40) methacrylate E-1: Methoxypolyethoxyethyl (n = 10) methacrylate E-2: Polyethylene glycol (n) = 10) Monomethacrylate

Test Category 2 (Preparation of early-strength concrete composition and its evaluation) Preparation of early-strength concrete composition The early-strength concrete composition of each example shown in Table 3 was prepared as follows. First, under the mixing conditions shown in Table 2, 20 ° C. × 80%
Under RH humidity control, early-strength Portland cement, fine aggregate and coarse aggregate were sequentially charged into a 50-liter pan-type forced mixer and kneaded for 15 seconds. Next, a cement dispersing agent was mixed and added together with water so that the target slump was within a range of 18 ± 1 cm in each case, and the mixture was kneaded for 2 minutes. The air amount was adjusted so that the target air amount was 4 ± 1 in each case.
% By adding an air flow regulator (Air flow regulator AE300 manufactured by Takemoto Yushi Co., Ltd.).

[0027]

[Table 2]

In Table 2, fast strength Portland cement: fast strength Portland cement manufactured by Chichibu Onoda Co., Ltd. (specific gravity 3.13) Fine aggregate: Nippon sea sand (specific gravity 2.54) / Ogashima crushed sand (specific gravity 2.13) 65) = 70/30 (volume ratio) mixture Coarse aggregate: crushed stone from Okazaki (specific gravity 2.66)

Evaluation of the prepared early-strength concrete composition The early-strength concrete composition of each prepared example was evaluated as follows. The results are shown in Table 3. Slump: Immediately after mixing, after further standing for 60 minutes and after standing for 90 minutes, the slump residual ratio was measured in accordance with JIS-A1101: (Slump after 90 minutes / Slump immediately after) × 100 Air volume: JIS- Measured according to A1128

[0030]

[Table 3]

In Table 3, * 1: The slump value immediately after did not reach the target slump value, and was not measured. * 2: There was no calculated value because there was no slump value after 90 minutes. Solid content equivalent to parts by weight

Test Category 3 (Preparation of cured product and its evaluation) Preparation of cured product 1) Preparation of cured product for measuring compressive strength The early-strength concrete composition of each example prepared in Test Category 2 was 10 cm in diameter × height. It was poured into a 20 cm steel cylindrical formwork. 2
One day aged at 0 ° C.
The specimens cured in water at 20 ° C. for 3 days or 28 days were used as a 3-year-old specimen and a 28-day specimen, respectively. 2) Preparation of cured product for measuring drying shrinkage The high-strength concrete composition of each example prepared in Test Category 2 was sized to 10 cm x 10 cm in accordance with JIS-A1132.
A test piece was poured into a steel rectangular frame having a size of × 40 cm and cured. 3) Preparation of a cured product for measuring the date of occurrence of cracks Using the early-strength concrete composition of each example prepared in Test Category 2, a JIS draft (cement concrete, 53-55)
P. 532, 1991) and stored at 20 ° C. × 60% RH as it was.

Evaluation of the prepared cured product Each specimen obtained in the above 1) to 3) was evaluated as follows. The results are shown in Table 4. Compressive strength: Measured according to JIS-A1108 Dry shrinkage: Crack occurrence date measured by a comparator method according to JIS-A1129: JIS draft (cement concrete, pages 53-55, 532, 199)
1 year) (This test method shows that cracks always occur due to restraint, and that the later the crack occurrence date is, the higher the crack resistance is.)

[0034]

[Table 4]

In Table 4, * 3: Not measured because the target slump value was not reached * 4: Not measured because the specimen could not be prepared

[0036]

As is clear from the above, the present invention described above has a small decrease in the fluidity over time of the prepared early-strength concrete composition, and at the same time achieves the same. There is an effect that a sufficient early strength can be expressed in the cured product to be obtained, and crack resistance can be enhanced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C04B 24:26) 103: 40 111: 20 (72) Inventor Keiji Ii 1-1-43- Matsugaedacho, Kita-ku, Kobe-shi, Hyogo Prefecture. 905 (72) Inventor Yasumine Maki 30, Yoshida, Oda, Kira-cho, Hazu-gun, Aichi Prefecture (72) Inventor Haruhiro Aoyama 238 Kitajima, Kitajima-cho, Toyohashi-shi, Aichi Prefecture 1-28-28 Form Gakuen-mae Room 201 (72) Inventor Mitsuo Kinoshita 308 Shiiki, Tameto-cho, Toyokawa City, Aichi Prefecture (56) References JP-A-7-309656 (JP, A) JP, A) JP-A-8-290955 (JP, A) JP-A-8-290948 (JP, A) JP-A-5-213653 (JP, A) JP-A-4-209613 (JP, A) JP Hei 5-11057 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB Name) C04B 24/26

Claims (2)

(57) [Claims] 1. An early-strength concrete composition prepared by using an early-strength Portland cement as a cement and further using water, fine aggregate, coarse aggregate and a cement dispersant, wherein the water / cement ratio is 30 to 65%; Unit water volume is 140-18
5 kg / m ^3, the unit amount of fine aggregate is 700~1200kg / m ³
And the unit amount of coarse aggregate is 800 to 1200 kg / m ³ , and the following cement dispersant is used in a ratio of 0.1 to 2.0 parts by weight with respect to 100 parts by weight of the early-strength Portland cement. An early-strength concrete composition characterized by the following. Cement dispersant: Consists of a structural unit A represented by the following formula 1, a structural unit B represented by the following formula 2, a structural unit C represented by the following formula 3, and a structural unit D represented by the following formula 4. Water-soluble vinyl copolymer, wherein in all the structural units,
45 to 65 mol% of the structural unit A, 2 to 15 of the structural unit B
Mol%, the constitutional unit C accounts for 5 to 20 mol% and the constitutional unit D accounts for 10 to 40 mol%, and the number average molecular weight is 2000
A water-soluble vinyl copolymer having a molecular weight of up to 20,000. (Equation 1) (Equation 2) (Equation 3) (Equation 4) (In the formulas 1 to 4, R ¹ , R ² : H or CH ₃ R ³ : phenyl group M ¹ , M ² : a cation group selected from an alkali metal, an alkaline earth metal and an organic amine m: 5 to 45 integer) 2. A cement dispersant comprising 50 to 65 mol% of the structural unit A, 3 to 15 mol% of the structural unit B, 7 to 20 mol% of the structural unit C and 15 to 15 mol% of the total structural units.
2. The early-strength concrete composition according to claim 1, which is a water-soluble vinyl copolymer occupying about 35 mol%.