JP3343163B2 - Concrete and method for producing high-strength concrete compact using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to concrete and a method for producing a high-strength concrete compact using the same.

[0002]

2. Description of the Related Art Conventionally, gypsum has been added for the purpose of increasing the initial strength of concrete, improving chemical resistance, and reducing drying shrinkage. However, natural anhydrite has a rapid elution of SO ₄ ions, and when added to concrete or mortar, false setting causes workability to deteriorate, and furthermore, the compressive strength of the material age 14 days after steam curing significantly decreases. There was a problem. Especially when the powder has a Blaine value of 3000 cm ² / g or more,
A 0.05% by weight aqueous solution of Na ₂ HPO _{4 at} a temperature of 20 ° C. 10
A natural anhydrous gypsum having an SO ₄ ion concentration of 0.15 to 1.5% by weight when 1 g of the aqueous solution was contacted for 1 hour with respect to 0 g of the aqueous solution was used in an amount of 5 to 20% by weight based on the amount of cement and naphthalene sulfone When an acid-based dispersant is used in concrete, the concrete causes false setting, which impairs workability such as transportation and molding.

Accordingly, an object of the present invention is to provide a concrete which does not have the above-mentioned drawbacks and has improved strength for 1, 1 and 7 days of age.

[0004]

Means for Solving the Problems In view of this situation, the present inventors have conducted intensive studies and found that natural anhydrous gypsum having a specific property can be added to concrete having a specific unit cement amount and a water cement ratio. The present inventors have found that a high-strength concrete molded article free of the above-mentioned disadvantages can be obtained by adding it together with a carboxylic acid-based dispersant, and completed the present invention.

That is, according to the present invention, a unit cement amount of 400
Up to 600 kg / m ³ and 35% by weight of water cement
Na ₂ H at a temperature of 20 ° C.
When a 1-hour contact 1g per 0.05 wt% aqueous solution 100g of PO _4, with respect to SO ₄ ion concentration unit cement content of natural anhydrous gypsum to be 0.15 to 1.5 wt% of the aqueous solution 5 to 20% by weight and a polycarboxylic acid cement dispersant in an amount of 0.1 to 2.
It is intended to provide concrete characterized by being blended at 0% by weight. The present invention also provides a method for producing a high-strength concrete molded body, which comprises molding the concrete and steam curing.

In the present invention, various mixed cements such as Portland cement, fly ash cement, silica cement and the like, which can be used as the cement, are usually of high strength, very high strength and moderate heat. Strong Portland cement is preferable because it can exhibit particularly excellent strength.

Further, the amount of cement in 1 m ^{3 of} concrete is 400 to 600 kg. When the amount is less than 400 kg, even when the cement dispersant is used to the maximum, the water-cement ratio becomes larger than 35% by weight and the 14-day strength is reduced. , Again 600
If it exceeds kg, the water-cement ratio becomes small, but the 14-day strength does not increase so much, and rather the cement paste is separated at the time of centrifugal molding, making compaction difficult, which is not preferable.
A particularly preferred unit cement amount is 470 for ordinary cement.
~ 550kg, 400 ~ 51 for fast and ultra fast cement
0 kg, as well as 530-600 kg for moderate heat cement.

The natural anhydrous gypsum used in the present invention preferably has a fineness (Brain value) of 3000 cm ² / g or more, and if it is less than 3000 cm ² / g, the strength development is reduced by half. A Blaine value of 4000 to 6000 cm ² / g is preferred from the viewpoint of developing stable strength and economical efficiency of pulverization. The method for measuring the SO ₄ ion of the natural anhydrous gypsum used in the present invention is as follows: 1 g of natural anhydrous gypsum is brought into contact with 100 g of a 0.05% by weight aqueous solution of Na ₂ HPO _{4 at} a temperature of 20 ° C. for 1 hour, followed by vacuum filtration. A method was employed in which barium chloride was added to the filtrate to precipitate barium sulfate, and the resulting solution was quantified as SO ₄ ion concentration. In the present invention, the SO
_{(4) A} soluble natural anhydrite having an ion concentration of 0.15 to 1.5% by weight is used. By using this in combination with a polycarboxylic acid-based dispersant, pseudo-coagulation can be prevented and high strength can be obtained. Because it is inexpensive. The addition amount of the natural anhydrous gypsum is 5 to 20% by weight, preferably 8 to 15% by weight, based on the amount of the unit cement. If the amount is less than 5% by weight or more than 20% by weight, the strength is not sufficient, which is not preferable. That is, the strength increases sharply from 5% by weight, shows a peak around 10% by weight, and decreases sharply when the amount exceeds 20% by weight.

In the concrete of the present invention, pseudo-coagulation can be prevented by using a polycarboxylic acid-based cement dispersant in combination, and workability can be improved. As the dispersant, those produced from ethylene oxide and maleic acid, for example, the following formula

[0010]

Embedded image

(Wherein, A represents an alkylene group having 1 to 5 carbon atoms, n represents a number of 5 to 20, and m represents 20 on a weight average)
(Indicating a number from 50 to 50) is preferred.

[0012] The polycarboxylic acid-based dispersant may be a commercially available one, for example, Tupole HP-8.
(Takemoto Yushi Co., Ltd.), Tupole HP-11 (Takemoto Yushi Co., Ltd.), Darrex Super 200
(Grace Japan Co., Ltd.), Maria Rim A-60
(Manufactured by NOF Corporation), Mariarim A-20 (manufactured by NOF Corporation), Mighty 2000WHZ (manufactured by Kao Corporation), Leo Build SP-8S (manufactured by Pozoris Bussan Co., Ltd.), Semerolu R-222M (manufactured by Toho Chemical Industry Co., Ltd.) and the like. The polycarboxylic acid-based cement dispersant has a random coil structure in the polycarboxylic acid-polyoxyalkylene graft polymer, and thus has a random coil structure, thereby maintaining the dispersion type of cement particles and reducing slump loss in order to reduce friction between particles. Can be greatly reduced. Further, the polycarboxylic acid-based dispersant is an oligomer having a molecular weight of several thousands to tens of thousands, and has a large chelating force (adsorption force) and a large charge providing force. Since the molecular weight is large, the amount of molecules surrounding the cement particles increases, and the hydratable area decreases. On the other hand, the sulfonic acid system has a large area that can be hydrated due to its small chelating power,
Since the dispersing power is higher than that of plain concrete, the total hydratable area increases and hydration is promoted, thereby causing slump loss. Further the case of using gypsum concrete, SO ₃ of the sulfonic group (SO ₃ H) promotes hydration of gypsum.

For the above reasons, the workability is improved by using a polycarboxylic acid-based dispersant in combination with the natural anhydrous gypsum.
High strength concrete is obtained. The amount of the dispersant added is 0.1 to 2.0% by weight, and preferably 0.3 to 1.3% by weight, based on the amount of the cement unit. 0.1
If the amount is less than 10% by weight, the water reducing effect is too small or the slump loss reducing effect is too small. If the amount exceeds 2.0% by weight, the setting of the cement is delayed, so that a longer pre-heating time is required and the strength after steam curing is reduced.

The concrete of the present invention can be produced by adding and mixing the above-mentioned components and other optional components as necessary by a conventional method, and by molding and steam-curing by a conventional method to obtain a high strength concrete. It can be a concrete molding.

[0015]

The concrete of the present invention has good workability because it does not cause false setting, and when it is molded, a concrete molded body having high strength can be obtained.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. Hereinafter, “%” indicates “% by weight” unless otherwise specified.

Example 1 Using natural anhydrous gypsum from Thailand consisting of the chemical components shown in Table 1,
Concrete tests were conducted according to the solubility of natural anhydrous gypsum.
Was. 489 kg / m of ordinary Portland cement ^Three, S
O_Three48.9 kg of natural anhydrous gypsum with ion concentration of 0.15%
/ M^Three, Ogasa sand land sand 547kg / m^Three, 11 crushed stones from Iwase
15kg / m^Three, 2.445 kg of polycarboxylic acid dispersant
/ M^ThreeAnd kneading water at 156kg / m^Three(This kneading water amount
Contains the amount of dispersant, the same applies hereinafter) and mix for over 90 seconds
It was kneaded with a mixer. This concrete slump
And the amount of air was measured. In addition, φ
Table vibrator on 10 × 20cm cylindrical specimen form
It was molded using. After 3 hours, heat up at 20 ℃ / hr
Temperature rise at a speed, hold at 75 ° C for 3 hours, then cool naturally
The compression strength at the time of demolding was measured. Then aerial curing
And the strength was measured on the 7th and 14th days. Measurement results
It is shown in Table 2. Here, the polycarboxylic acid-based dispersant is a commercial product
The name Darrex Super 200 was used.

Examples 2 to 4 Concrete was molded in the same manner as in Example 1 except that the solubility of natural anhydrous gypsum and the amount of dispersant added were changed, and the same evaluation as in Example 1 was performed. Table 2 also shows the measurement results of Examples 1 to 4.

[0019]

[Table 1]

[0020]

[Table 2]

COMPARATIVE EXAMPLE 1 489 kg / m ^{3 of} ordinary Portland cement, 48.9 kg / m ³ of natural anhydrous gypsum having an SO ₄ ion concentration of 0.10%,
Ogasa sand land sand 547 kg / m ³ , Iwase crushed stone 1115 kg
/ M ^3, a polycarboxylic acid-based dispersant 2.445kg / m ^3,
156 kg / m ^{3 were} mixed with the kneading water and kneaded with a forced mixer for 90 seconds. Thereafter, the same operation and evaluation were performed as in Example 1. The cement dispersant used was Darrex Super 200.

Comparative Examples 2 to 3 Concrete was molded in the same manner as in Comparative Example 1 except that the solubility of natural anhydrite and the amount of the dispersant added were changed, and the same evaluation as in Example 1 was performed. Table 3 also shows the measurement results of Comparative Examples 1 to 3.

[0023]

[Table 3]

[0024] Example 5 Ordinary Portland cement to 489kg / m ^3, SO ₄ ion concentration 0.6% natural anhydrite of 48.9 kg / m ^3, Ogasa Sunarikusuna a 547kg / m ^3, Iwase production crushed stone 1115kg /
m ^3, a polycarboxylic acid-based dispersant 3.912kg / m ^3, and the kneading water 153 kg / m ³ were mixed kneaded for 90 seconds positive mixer. Thereafter, the same operation and evaluation were performed as in Example 1.

Examples 6 to 8 Concrete was molded in the same manner as in Example 1 except that the amount of the added natural anhydrite from Thailand and the amount of the dispersant were changed. Table 4 also shows the measurement results of Examples 5 to 8.

[0026]

[Table 4]

[0027] Comparative Example 4 ordinary portland cement to 489kg / m ^3, SO ₄ ion concentration 0.6% natural anhydrite of 18 kg / m ^3, Ogasa Sunarikusuna a 547kg / m ^3, Iwase-producing crushed stone 1115kg / m ³ ,
Polycarboxylic acid-based dispersant 3.912kg / m ^3, and the kneading water 153 kg / m ³ were mixed kneaded for 90 seconds positive mixer. Thereafter, the same operation and evaluation were performed as in Example 1.

Comparative Example 5 Concrete was molded by changing the addition amount of the natural anhydrous gypsum from Thailand and the addition amount of the dispersant, and the same operation as in Comparative Example 4 was performed and evaluated in the same manner as in Example 1. Table 5 also shows the measurement results of Comparative Examples 4 and 5.

[0029]

[Table 5]

Example 9: 489 kg / m ^{3 of} ordinary Portland cement and 73.35 kg / of natural anhydrous gypsum having an SO ₃ ion concentration of 0.75%
m ³ , Ogasa sand land sand 561 kg / m ³ , Iwase crushed stone 114
5 kg / m ³ , 2.445 kg / polycarboxylic acid dispersant
147 kg / m ^{3 of} m ³ and kneading water were mixed and kneaded with a forced mixer for 90 seconds. Thereafter, the same operation and evaluation were performed as in Example 1.

Examples 10 to 12 By changing the amount of the polycarboxylic acid-based dispersant,
Concrete was molded and operated and evaluated as in Example 9.
Was. SO of the natural anhydrous gypsum from Thailand used at this time _Fourion
The concentration is 0.75% and the amount of gypsum added is unit cement.
15% with respect to the amount of water. Table 6 shows the measurements of Examples 9 to 12.
The results are shown below.

[0032]

[Table 6]

Comparative Examples 6 to 7 Concrete was molded by using the formulations shown in Table 7 and changing the amount of the polycarboxylic acid-based dispersant added, and evaluated in the same manner as in Example 1. Table 8 shows the measurement results of Comparative Examples 6 and 7.

[0034]

[Table 7]

[0035]

[Table 8]

Examples 13 to 15 With the composition shown in Table 9, a unit of cement was kept constant, and a concrete molded body was formed by changing the water-cement ratio and the amount of the dispersant added. did. The natural anhydrous gypsum produced in Thailand used at this time had an SO ₄ ion concentration of 0.1.
The amount of gypsum was 10% with respect to the unit cement amount. Table 10 shows the measurement results of Examples 13 to 15.

[0037]

[Table 9]

[0038]

[Table 10]

COMPARATIVE EXAMPLE 8 A concrete molded body was molded with the composition shown in Table 11 and the unit cement amount was kept constant, the water-cement ratio and the amount of the dispersant added were changed, and evaluated in the same manner as in Example 1. The SO ₄ ion concentration of the natural anhydrous gypsum from Thailand used at this time was 0.75
%, And the added amount of gypsum is 10 to the unit setont amount.
%. Table 12 shows the measurement results of Comparative Example 8.

[0040]

[Table 11]

[0041]

[Table 12]

Examples 16 to 20 Table 13 lists the types of commercially available polycarboxylic acid-based dispersants and the amounts added per unit cement, and evaluated in the same manner as in Example 1 using the formulation of Example 1. did. Table 13 also shows the measurement results.

[0043]

[Table 13]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C04B 22:14 C04B 24:26 H 24:26) 103: 40 103: 40 (72) Inventor Noboru Miyazaki 1 Marunouchi, Chiyoda-ku, Tokyo -8-2 Second Steel Building Onoda Cement Co., Ltd. Cement Sales Division (72) Inventor Atsushi Kameoka 2-4-2 Daisaku, Sakura-shi, Chiba Onoda Cement Co., Ltd. Central Research Laboratory (56) References JP Akira 53-49021 (JP, A) JP-A-52-98730 (JP, A) JP-A-57-47752 (JP, A) JP-A-6-219803 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B ^7/ 00-28/36

Claims (4)

(57) [Claims] 1. A unit cement amount of 400 to 600 kg / m ³
, And the and the concrete material is 35 wt% or less water-cement ratio, SO ₄ ions in the aqueous solution when the 1g 1-hour contact with respect to 0.05 wt% aqueous solution 100g of temperature 20 ° C. of Na ₂ HPO ₄ A natural anhydrous gypsum having a concentration of 0.15 to 1.5% by weight is added in an amount of 5 to 2 per unit cement.
0% by weight and 0.1 to 2.0% by weight of a polycarboxylic acid-based cement dispersant with respect to a unit cement amount. 2. The concrete according to claim 1, wherein the water cement ratio is 24-28% by weight. 3. The polycarboxylic acid-based cement dispersant has the following formula: (Wherein, A represents an alkylene group having 1 to 5 carbon atoms, n represents a number of 5 to 20, and m represents a number of 20 to 50 by weight average). Concrete. 4. A method for producing a high-strength concrete molded product, comprising molding the concrete according to claim 1, 2 or 3, and steam curing the concrete.