JP2010006626A - Method of preparing ultra low shrinkage ae concrete and ultra low shrinkage ae concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of preparing ultra low shrinkage AE (Air Entrained) concrete by which drying shrinkage rate of a resultant hardened body is suppressed to an extremely low region of ≤200 μm without adversely affecting the fluidity or entrained air quantity of the obtained ultra low shrinkable AE concrete and the strength of the resultant hardened body and the neutralization is simultaneously reduced and to provide the ultra low shrinkage AE concrete. <P>SOLUTION: Specific blast furnace slag fine aggregate is used at least as a part of fine aggregate in a ratio of 250-950 kg/m<SP>3</SP>as unit amount, specific crushed limestone is used as coarse aggregate in a ratio of 800-1,100 kg/m<SP>3</SP>as unit amount, specific (poly)alkylene glycol monoalkyl ether is used as a drying shrinkage reducing agent in a ratio of 4-25 kg/m<SP>3</SP>as unit amount and the ratio of unit amount measured by a relation, [ä(unit amount of water+unit amount of drying shrinkage reducing agent)/(unit amount of cement)}×100] is controlled to 35-65%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for preparing ultra-low shrinkage AE concrete and ultra-low shrinkage AE concrete. In recent years, from the viewpoint of extending the life and quality of a concrete structure, the concrete structure is required to suppress the occurrence of cracks due to drying shrinkage, and at the same time, it is required to have little neutralization. It has become. In order to suppress cracking due to drying shrinkage of a concrete structure, it is necessary to set the drying shrinkage rate to about 600 μm or less in a general building, and the drying shrinkage rate in a building where the cross-section of a restraint member such as an underground structure is large. On the other hand, in an actual construction site, if the drying shrinkage rate exceeds 200μ at a part where the opening and the reinforcing bar are constrained, the generation of cracks is sufficient. It has also been pointed out that it is difficult to control. In order to sufficiently suppress the occurrence of cracks due to drying shrinkage in the concrete structure, it is necessary to suppress the drying shrinkage rate to an extremely small region of 200 μm or less. The present invention provides a method for preparing an ultra-low-shrinkage AE concrete capable of sufficiently suppressing the occurrence of cracks due to drying shrinkage of the resulting concrete structure (hereinafter simply referred to as a cured product) and at the same time reducing neutralization. It relates to ultra-low shrinkage AE concrete.

  Conventionally, as means for reducing the drying shrinkage rate of concrete, various dry shrinkage reducing agents are used at the time of preparing the concrete (for example, see Patent Documents 1 and 2), and an expansion material is used (for example, Patent Document 3). (See, for example, Patent Document 4).

However, the conventional means does not adversely affect the fluidity and entrained air amount of the prepared concrete and the strength of the obtained cured body, and the drying shrinkage rate of the obtained cured body is in an extremely small region of 200 μm or less. There is a problem that it cannot be suppressed and neutralization cannot be reduced.
Japanese Patent Laid-Open No. 56-037259 Japanese Patent Laid-Open No. 2-307849 JP 11-302047 A JP 2004-168606 A

  The problem to be solved by the present invention is that the dry shrinkage rate of the obtained cured product is 200 μm or less without adversely affecting the fluidity and entrained air amount of the prepared ultra-low shrinkage AE concrete and the strength of the obtained cured product. Therefore, the present invention provides a method for preparing ultra-low-shrinkage AE concrete and ultra-low-shrinkage AE concrete that can be suppressed to an extremely small area and at the same time reduce neutralization.

  As a result, the present inventors have studied to solve the above-mentioned problems. As a result, specific aggregates, coarse aggregates, and dry shrinkage reducing agents are used, and such specific fine aggregates, coarse aggregates and dry aggregates are used. It has been found that the use of a shrinkage reducing agent in a predetermined proportion is correct and suitable.

That is, the present invention provides at least one of fine aggregates when preparing ultra-low-shrinkage AE concrete using at least cement, water, fine aggregate, coarse aggregate, dry shrinkage reducing agent, cement dispersant, and air amount adjusting agent. the blast-furnace slag fine aggregate below used in a proportion of unit quantity 250~950kg / ^{m 3} as parts, also using lime crushed stone below at a rate of a unit amount 800~1100kg / ^{m 3} as coarse aggregate, further dried below An ultra-low-shrinkage AE concrete characterized in that a shrinkage reducing agent is used at a rate of unit amount of 4 to 25 kg / m ³ , and the unit amount ratio calculated by the following formula 1 is 35 to 65%. It relates to the preparation method. The present invention also relates to ultra-low shrinkage AE concrete obtained by such a preparation method.

  Blast furnace slag fine aggregate: A blast furnace slag fine aggregate included in the blast furnace slag fine aggregate classification according to JIS-A5011-1 and having a coarse rate of 1.2 to 4.0. thing

  Limestone: Limestone containing CaO ≧ 50% by mass and MgO ≦ 2% by mass

  Drying shrinkage reducing agent: (poly) alkylene glycol monoalkyl ether represented by the following chemical formula 1

In chemical formula 1,
R: an alkyl group having 3 or 4 carbon atoms A: (poly) oxy composed of only 1 to 3 oxyethylene units in the molecule or a total of 2 to 5 oxyethylene units and oxypropylene units in the molecule Residues obtained by removing all hydroxyl groups from (poly) alkylene glycol having an alkylene group

  The method for preparing ultra-low shrinkage AE concrete according to the present invention (hereinafter simply referred to as the preparation method of the present invention) includes at least cement, water, fine aggregate, coarse aggregate, dry shrinkage reducing agent, cement dispersant, and air amount adjustment. This is a method for preparing ultra-low-shrinkage AE concrete using an agent.

  The fine aggregate used in the preparation method of the present invention uses blast furnace slag fine aggregate as at least a part thereof. This blast furnace slag fine aggregate is a blast furnace slag fine aggregate included in the classification according to the grain size of the blast furnace slag fine aggregate described in JIS-A5011-1. The coarse particle ratio is adjusted to 1.2 to 4.0. It is a thing. Especially, as a blast furnace slag fine aggregate, the classification by a particle size is a blast furnace slag fine aggregate, Comprising: The coarse particle ratio adjusted to 1.5-3.2 is preferable. The origin of the blast furnace slag fine aggregate is not particularly limited, but blast furnace granulated slag fine aggregate is preferable. Here, the coarse particle ratio (abbreviated as fineness modulus, FM) is 80, 40, 20, 10, 5, 2.5, 1.2, 0.6, 0.3 and 0.00. The value obtained by dividing by 100 the sum of the weight percentages of all the samples that do not pass through each sieve when a screening test is performed using a set of 15 sieves (unit: mm). As such, it is a term commonly used as a cement concrete term.

The blast furnace slag fine aggregate described above is used at a rate of a unit amount of 250 to 950 kg / m ³ , but preferably at a rate of 400 to 900 kg / m ³ . Examples of the fine aggregate other than the blast furnace slag fine aggregate include river sand, mountain sand, sea sand, crushed sand, etc., but the blast furnace slag fine aggregate preferably uses 30% by mass or more of the whole fine aggregate, and more Preferably 50 mass% or more is used.

The coarse aggregate used in the preparation method of the present invention is crushed limestone containing CaO ≧ 50 mass% and MgO ≦ 2 mass%. It is known that when AE concrete is prepared, the dry shrinkage rate of the resulting cured body can be made relatively small when lime crushed stone is used as the coarse aggregate. However, generally only using crushed limestone as the coarse aggregate can only suppress the drying shrinkage of the obtained cured product to about 400 to 650 μm. Assuming that other conditions are satisfied, among the lime crushed stones, the use of a specific crushed crushed stone containing CaO in a proportion of 50 mass% or more and MgO in a proportion of 2 mass% or less is the first The drying shrinkage can be suppressed to 200 μm or less. Such lime crushed stone is used in a proportion of unit quantity 800~1100kg / ^{m 3,} preferably used in a proportion of unit quantity 850~1050kg / ^{m 3.}

The drying shrinkage reducing agent used in the preparation method of the present invention is a (poly) alkylene glycol monoalkyl ether represented by Chemical Formula 1. R in Chemical Formula 1 is an alkyl group having 3 or 4 carbon atoms, and examples thereof include a propyl group and a butyl group, and among them, a butyl group having 4 carbon atoms is preferable. The butyl group includes isomers such as a normal butyl group, an isobutyl group, a secondary butyl group, and a tertiary butyl group. Among them, R is preferably a normal butyl group. A in Chemical Formula 1 has a (poly) oxyalkylene group composed of only 1 to 3 oxyethylene units or a total of 2 to 5 oxyethylene units and oxypropylene units in the molecule. A residue obtained by removing all hydroxyl groups from glycol. Therefore, the (poly) alkylene glycol monoalkyl ether represented by Chemical Formula 1 is 1) a (poly) ethylene glycol monoalkyl having a (poly) oxyethylene group composed of only 1 to 3 oxyethylene units in the molecule. Alkyl ethers 2) (poly) alkylene glycol monoalkyl ethers having a (poly) oxyalkylene group composed of a total of 2 to 5 oxyethylene units and oxypropylene units in the molecule are included. Here, the bonding mode of the oxyethylene unit and the oxypropylene unit may be random or block. Of the drying shrinkage reducing agents described above, diethylene glycol monobutyl ether is preferable. The drying shrinkage reducing agent is used in a unit amount of 4 to 25 kg / m ³ , but preferably in a rate of 8 to 20 kg / m ³ .

  Examples of the air amount adjusting agent used in the preparation method of the present invention include polyoxyalkylene alkyl ether sulfate, alkyl benzene sulfonate, polyoxyethylene alkyl benzene sulfonate, rosin soap, higher fatty acid soap, alkyl phosphate ester salt, polyoxy An alkylene alkyl ether phosphate ester salt and the like can be mentioned, among which an alkyl phosphate monoester salt is preferable, and an octyl phosphate monoester potassium salt is more preferable. Such an air amount adjusting agent is usually used at a ratio of 0.001 to 0.01 parts by mass per 100 parts by mass of cement.

  Examples of the cement dispersant used in the preparation method of the present invention include lignin sulfonate type, naphthalene sulfonate formalin high condensate type, polycarboxylate type, and the like. A polycarboxylate cement dispersant made of a vinyl copolymer (for example, those described in JP-A-58-74552 and JP-A-1-226757) is preferred. Such a cement dispersant is usually used at a ratio of 0.05 to 2 parts by mass per 100 parts by mass of cement.

  As the cement used in the preparation method of the present invention, various portland cements such as ordinary Portland cement, early-strength Portland cement, moderately hot Portland cement, low heat Portland cement, and various types of mixed blast furnace cement, fly ash cement, silica fume cement and the like. Examples of the cement include super early strength cement and alumina cement. Of these, ordinary Portland cement is preferable.

  In the preparation method of the present invention, at least as described above, cement, fine aggregate, coarse aggregate, dry shrinkage reducing agent, cement dispersant, air amount adjusting agent, and further kneading with water, ultra-low shrinkage AE Prepare concrete. During the preparation, the mixing procedure of cement, water, fine aggregate, coarse aggregate, drying shrinkage reducing agent, cement dispersant and air amount adjusting agent is not particularly limited, but the required amount of cement, water, fine aggregate is first used. A method of kneading a drying shrinkage reducing agent, an air entraining agent and a cement dispersant and then kneading the coarse aggregate is preferable.

  In the preparation method of the present invention, the amount of entrained air is usually 3 to 8% by volume, but preferably 3 to 7% by volume.

  In the preparation method of the present invention, as described above, at least cement, water, fine aggregate, coarse aggregate, dry shrinkage reducing agent, cement dispersant and air amount adjusting agent are kneaded, and ultra low shrinkage AE concrete is obtained. Prepare. At this time, in the preparation method of the present invention, the unit amount ratio obtained by the above formula 1 is set to 35 to 65%, preferably 40 to 60%.

  In the preparation method of the present invention, additives such as a rust preventive, a quick setting agent, a setting accelerator, a setting retarder, and a waterproofing agent can be used in combination within the range not impairing the effects of the present invention. .

  The ultra-low-shrinkage AE concrete according to the present invention is prepared by the above-described preparation method of the present invention, and the drying shrinkage of the cured product obtained therefrom can be suppressed to 200 μm or less. Neutralization, which is a durability improvement item, can be reduced.

  The ultra-low-shrinkage AE concrete according to the present invention can be applied not only as an ultra-low-shrinkage AE concrete placed at a construction site, but also as an ultra-low-shrinkage AE concrete for a secondary product processed at a concrete product factory.

  According to the present invention, the dry shrinkage rate of the obtained hardened body is suppressed to 200 μm or less without significant adverse effects on the fluidity and air entrainment amount of the prepared AE concrete and the strength of the obtained hardened body, and is neutralized. There is an effect that it is possible to provide ultra-low-shrinkage AE concrete with less durability and excellent durability.

  Hereinafter, in order to make the configuration and effects of the present invention more specific, examples and the like will be described. However, the present invention is not limited to the examples. In the following examples and the like, unless otherwise indicated,% means mass%, and part means mass part.

Test category 1 (Preparation of ultra-low shrinkage AE concrete)
Example 1
Under the mixing conditions described in Table 1, a 50 L pan-type forced kneader was mixed with ordinary Portland cement (density = 3.16 g / cm ³ , brain value 3300), blast furnace slag fine aggregate (S-1 described in Table 2). , Blast furnace slag fine aggregate with a particle size classification of 5 mm, with a coarse particle ratio adjusted to 2.55, density = 2.70 g / cm ³ , natural sand (land sand from Kamisu, coarse particle ratio = 2.60, density = 2.62 g / cm ³ ), air amount regulator (octyl phosphate monoester potassium salt), cement dispersant (polycarboxylate cement dispersant manufactured by Takemoto Yushi Co., Ltd., trade name Tupol) The required amounts of HP-11) and the drying shrinkage reducing agent (A-1, diethylene glycol monobutyl ether described in Table 4) were added together with kneaded water (tap water) and kneaded for 45 seconds. Next, coarse aggregate (G-1 listed in Table 3, Chichibu limestone, density = 2.70 g / cm ³ ) is added and mixed for 60 seconds, the target slump is 18 ± 1 cm, and the target air volume is An ultra-low-shrinkage AE concrete of Example 1 having a range of 4.5 ± 1% was prepared. In addition, the usage-amount of the air quantity regulator and the cement dispersing agent was shown in the footnote of Table 1.

Examples 2-12
In the same manner as in Example 1, ultra-low shrinkage AE concrete was prepared under the blending conditions shown in Table 1, respectively.

Comparative Example 1
Under the blending conditions shown in Table 1, ordinary Portland cement (density = 3.16 g / cm ³ , brain value 3300), blast furnace slag fine aggregate (S-1, described in Table 2, Blast furnace slag fine aggregate with a particle size classification of 5 mm, with a coarse particle ratio adjusted to 2.55, density = 2.70 g / cm ³ , natural sand (Kamisu land sand, coarse particle ratio = 2 .60, density = 2.62 g / cm ³ ), air amount regulator (octyl phosphate monoester potassium salt), cement dispersant (polycarboxylate-based cement dispersant manufactured by Takemoto Yushi Co., Ltd., trade name Tupole HP -11) and a required amount of a drying shrinkage reducing agent (A-1, diethylene glycol monobutyl ether described in Table 4) were added together with kneaded water (tap water) and kneaded for 45 seconds. Next, coarse aggregate (G-1 listed in Table 3, Chichibu limestone, density = 2.70 g / cm ³ ) is added and mixed for 60 seconds, the target slump is 18 ± 1 cm, and the target air volume is An ultra-low-shrinkage AE concrete of Comparative Example 1 having a range of 4.5 ± 1% was prepared. In addition, the usage-amount of the air quantity regulator and the cement dispersing agent was shown in the footnote of Table 1.

Comparative Examples 2 to 21
In the same manner as in Comparative Example 1, ultra-low shrinkage AE concrete was prepared under the blending conditions shown in Table 1, respectively.

In Table 1,
Unit amount: Unit is kg / m ³
Use amount of air amount regulator: Examples 1 to 6 and Comparative Examples 1 to 10 are 0.005 parts with respect to 100 parts of ordinary Portland cement, and Examples 7 to 12 and Comparative Examples 11 to 21 are 0.006. A proportion of parts Amount of cement dispersant used: A proportion of 0.9 parts in Examples 1 to 6 and Comparative Examples 1 to 10, and 1 in Examples 7 to 12 and Comparative Examples 11 to 21 with respect to 100 parts of ordinary Portland cement. 0.0 part ratio Blast Furnace Slag Fine Aggregate: as described in Table 2 below Natural Sand: Land sand from Kamisu, Coarse Grain = 2.60, Density = 2.62 g / cm ³
Limestone: listed in Table 3 below Drying shrinkage reducing agent: listed in Table 4 below Cement: Normal Portland cement with density = 3.16 g / cm ³ and Blaine value 3300 Target slump: 18 for each example ± 1cm
Target air volume: 4.5 ± 1% in all cases

Test category 2 (Evaluation of ultra-low shrinkage AE concrete)
About the ultra-low-shrinkage AE concrete of each example prepared in Test Category 1, the entrained air amount and slump were determined as follows, and the results are shown in Table 5. Moreover, about the hardened | cured material of the ultra-low-shrinkage AE concrete of each example, the drying shrinkage rate, the accelerated neutralization depth, and the compressive strength were calculated | required as follows, and the result was put together in Table 5 and shown.

Entrained air amount (volume%): Measured according to JIS-A1128 for ultra-low shrinkage AE concrete immediately after mixing.
-Slump (cm): Measured according to JIS-A1101 simultaneously with the measurement of the air amount.

-Drying shrinkage rate (μ): In accordance with JIS-A1129, dry shrinkage strain was measured by a comparator method on a 26-week-old specimen in which each ultra-low-shrinkage AE concrete was stored at 20 ° C x 60% RH. Was measured to determine the drying shrinkage. The smaller this value, the smaller the drying shrinkage.
-Accelerated neutralization depth (mm): For each ultra-low-shrinkage AE concrete, a 10 cm x 10 cm x 40 cm square specimen was formed and the other five surfaces were sealed with epoxy resin except for the top surface. The acceleration test was conducted under the conditions of 20 ° C. × 60% RH and carbon dioxide concentration of 5%. A rectangular specimen was cut in a longitudinal section at the age of 13 weeks, and a 1% phenolphthalein solution was sprayed to make a portion that was not reddened a non-neutralized portion, and a width from the upper surface was defined as an accelerated neutralization depth. A smaller value indicates that neutralization does not progress and durability is excellent.
-Compressive strength (N / mm < ² >): About the ultra-low shrinkage | contraction AE concrete of each example, based on JIS-A1108, it measured by material age 7 days and material age 28 days.

Claims (11)

When preparing an ultra-low shrinkage AE concrete using at least cement, water, fine aggregate, coarse aggregate, dry shrinkage reducing agent, cement dispersant, and air amount adjusting agent, at least a part of the fine aggregate is as follows: with slag sand in the ratio of the unit amount 250~950kg / ^{m 3,} also using lime crushed stone below at a rate of a unit amount 800~1100kg / ^{m 3} as coarse aggregate, further units of drying shrinkage-reducing agent of the following A method for preparing ultra-low-shrinkage AE concrete, characterized in that it is used at a rate of ^{4 to} 25 kg / m ³ , and the unit rate determined by the following formula 1 is 35 to 65%.
Blast furnace slag fine aggregate: A blast furnace slag fine aggregate included in the blast furnace slag fine aggregate classification according to JIS-A5011-1 and having a coarse rate of 1.2 to 4.0. Lime crushed stone: Lime crushed stone containing CaO ≧ 50 mass% and MgO ≦ 2 mass% Drying shrinkage reducing agent: (poly) alkylene glycol monoalkyl ether represented by the following chemical formula 1

(In chemical formula 1,
R: an alkyl group having 3 or 4 carbon atoms A: (poly) oxy composed of only 1 to 3 oxyethylene units in the molecule or a total of 2 to 5 oxyethylene units and oxypropylene units in the molecule Residue obtained by removing all hydroxyl groups from (poly) alkylene glycol having an alkylene group)

  Preparation of ultra-low-shrinkage AE concrete according to claim 1, wherein the blast furnace slag fine aggregate is a blast furnace slag fine aggregate having a particle size classification of 5 mm and having a coarse particle ratio adjusted to 1.5 to 3.2. Method. Process for the preparation of ultra-low shrinkage AE concrete according to claim 1 or 2, wherein using blast furnace slag sand in the ratio of the unit amount 400~900kg / ^{m 3.} The method for preparing ultra-low-shrinkage AE concrete according to any one of claims 1 to ³ , wherein diethylene glycol monobutyl ether is used as a drying shrinkage reducing agent in a unit amount of 8 to 20 kg / m ³ .   The method for preparing ultra-low-shrinkage AE concrete according to any one of claims 1 to 4, wherein the air amount regulator is an alkyl phosphate monoester salt.   The method for preparing ultra-low shrinkage AE concrete according to any one of claims 1 to 5, wherein the cement dispersant is a polycarboxylate-based cement dispersant.   The method for preparing an ultra-low shrinkage AE concrete according to any one of claims 1 to 6, wherein the cement is ordinary Portland cement.   The method for preparing ultra-low shrinkage AE concrete according to any one of claims 1 to 7, wherein the amount of air is 3 to 7% by volume.   The method for preparing ultra-low shrinkage AE concrete according to any one of claims 1 to 8, wherein the unit amount ratio is 40 to 60%.   Ultra-low shrinkage AE concrete obtained by the method for preparing ultra-low shrinkage AE concrete according to any one of claims 1 to 9.   The ultra-low-shrinkage AE concrete according to claim 10, wherein the obtained cured product has a drying shrinkage of 200 µm or less.