JP5058098B2 - Method for preparing low shrinkage AE concrete for civil engineering and low shrinkage AE concrete for civil engineering - Google Patents

Description

  The present invention relates to a method for preparing a low-shrinkage AE concrete for civil engineering and a low-shrinkage AE concrete for civil engineering. To improve the quality and durability of low-shrinkage AE concrete for civil engineering, which is prepared in recent years with a target slump that has been kept relatively low using a multifunctional admixture for convenience in use. Specifically, 1) First, as a premise, the multifunctional admixture used is excellent in stability, and 2) The fluidity of the prepared low-shrinkage AE concrete for civil engineering and the decrease in the amount of air over time 3) Low drying shrinkage rate of the resulting cured product, 4) Strong resistance to freeze-thaw action of the resulting cured product, and 5) of the resulting cured product. It is required that the neutralization rate is slow, 6) the compressive strength of the resulting cured product is correspondingly excellent, and the above 1) to 6) are simultaneously satisfied. The present invention relates to a method for preparing low-shrinkage AE concrete for civil engineering that meets such requirements, and a low-shrinkage AE concrete for civil engineering prepared by this preparation method.

  Conventionally, various cement dispersants mainly composed of polycarboxylic acid-based compounds as admixtures that impart excellent fluidity to the low-shrinkage AE concrete for civil engineering and exhibit excellent compressive strength in the resulting cured product Is known (see, for example, Patent Documents 1 and 2). Various dry shrinkage reducing agents are also known as admixtures that lower the drying shrinkage of the resulting cured product (see, for example, Patent Document 3). Furthermore, an admixture that imparts fluidity to the low-shrinkage AE concrete for civil engineering and lowers the drying shrinkage of the resulting cured product is also known (see, for example, Patent Documents 4 and 5).

However, when such conventional admixtures are used, there is a problem that the requirements 1) to 6) described above cannot be satisfied at the same time even if they are used together as appropriate.
JP 58-74552 A JP-A-1-226757 Japanese Patent Publication No.59-3430 JP 2004-262715 A JP 2007-153652 A

  The problem to be solved by the present invention is to prepare a low-shrinkage concrete for civil engineering in which the slump immediately after kneading is kept relatively low using a multifunctional admixture for convenience of use. The multifunctional admixture is excellent in stability, 2) the flowability of the prepared low-shrinkage AE concrete for civil engineering and the reduction of the air volume over time are ensured, and good workability is ensured. Low drying shrinkage of the cured product 4) Strong resistance to freeze-thaw action of the resulting cured product 5) Slow neutralization rate of the resulting cured product 6) Compression of the resulting cured product The present invention provides a method for preparing a low-shrinkage AE concrete for civil engineering and a low-shrinkage AE concrete for civil engineering that satisfies the above-mentioned 1) to 6) at the same time.

  As a result, the present inventors have studied to solve the above-mentioned problems. As a result, the cement is used at a predetermined ratio, and a specific multifunctional admixture composed of specific three components is used at a predetermined ratio with respect to the cement. It has been found that it is correctly suitable to prepare a low-shrinkage AE concrete for civil engineering with a predetermined slump and entrained air (AE) amount.

That is, according to the present invention, when preparing low-shrinkage AE concrete for civil engineering using cement, water, fine aggregate, coarse aggregate, multifunctional admixture and air amount adjusting agent, the unit amount of cement is 290 to 450 kg / m ^3. In addition, the following multifunctional admixture is used at a ratio of 0.3 to 1.5 parts by mass per 100 parts by mass of cement, and a slump immediately after mixing is further adjusted to a range of 6 to 15 cm and entrained. The present invention relates to a method for preparing low-shrinkage AE concrete for civil engineering, characterized in that the amount of air is adjusted to a range of 3 to 8% by volume. Moreover, this invention relates to the low shrinkage AE concrete for civil engineering prepared by the preparation method of this low shrinkage AE concrete for civil engineering.

  Multifunctional admixture: Consists of the following cement dispersant, drying shrinkage reducing agent and separation reducing agent, the cement dispersing agent being 10 to 30% by mass, the drying shrinkage reducing agent being 65 to 85% by mass and the separation reducing agent Containing 0.05 to 5 mass% (total 100 mass%)

  Cement dispersant: Mass having 45 to 85 mol% of the following structural unit D, 15 to 55 mol% of the following structural unit E, and 0 to 5 mol% of the following structural unit F (total 100 mol%) in the molecule. Water-soluble vinyl copolymer having an average molecular weight of 2000 to 70000

Structural unit D: one or two or more selected from structural units formed from methacrylic acid and structural units formed from methacrylic acid salt Structural unit E: composed of 7 to 75 oxyethylene units in the molecule Structural unit formed from methoxypolyethyleneglycol methacrylate having a polyoxyethylene group formed Structural unit F: selected from a structural unit formed from (meth) allyl sulfonate and a structural unit formed from methyl (meth) acrylate One or more

  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 to 5 carbon atoms A: a residue obtained by removing all hydroxyl groups from a (poly) alkylene glycol having a (poly) oxyalkylene group composed of only 1 to 5 oxyethylene units in the molecule

  Separation-reducing agent: polyvinyl alcohol synthesized from polyvinyl acetate having a saponification degree of 80 to 95 mol% and a viscosity of 4% by weight aqueous solution at 20 ° C. in the range of 1 to 50 mPa · s

  In the method for preparing low-shrinkage AE concrete for civil engineering according to the present invention (hereinafter referred to as the preparation method of the present invention), in addition to cement, water, fine aggregate, and coarse aggregate, a multifunctional admixture and an air amount adjusting agent are added. Use. The multifunctional admixture used in the preparation method of the present invention comprises a cement dispersant, a drying shrinkage reducing agent, and a separation reducing agent.

  The cement dispersant used as one component of the multifunctional admixture is 1) a water-soluble vinyl copolymer composed of the structural unit D and the structural unit E, or 2) the structural unit D, the structural unit E, and the structural unit F. Is a water-soluble vinyl copolymer composed of

  The structural unit D includes 1) a structural unit formed from methacrylic acid, 2) a structural unit formed from methacrylate, 3) a structural unit formed from methacrylic acid, and a structural unit formed from methacrylate. Both are mentioned. Here, structural units formed from methacrylates are as follows: a) structural units formed from alkali metal salts such as lithium, sodium, and potassium methacrylic acid, and b) alkaline earths such as calcium and magnesium methacrylates. Examples include structural units formed from metal salts, and c) structural units formed from organic amine salts such as diethanolamine and triethanolamine of methacrylic acid. Especially, as the structural unit D, the structural unit formed from the methacrylate is preferable, and the structural unit formed from sodium methacrylate is more preferable.

  The structural unit E is a structural unit formed from methoxypolyethylene glycol methacrylate having a polyoxyethylene group composed of 7 to 75 oxyethylene units in the molecule.

  As the structural unit F, 1) a structural unit formed from (meth) allyl sulfonate, 2) a structural unit formed from methyl (meth) acrylate, and 3) a structure formed from (meth) allyl sulfonate. Both the unit and the structural unit formed from methyl (meth) acrylate are mentioned. Examples of the structural unit formed from such (meth) allyl sulfonate include a structural unit formed from allyl sulfonate and a structural unit formed from methallyl sulfonate. Examples of the salt include lithium and sodium. And alkali metal salts such as potassium, sodium salt is preferred.

  When the cement dispersant is composed of the water-soluble vinyl copolymer composed of the structural unit D and the structural unit E as described above, the water-soluble vinyl copolymer contains 45 to 85 mol% of the structural unit D in the molecule. The structural unit E has a proportion of 15 to 55 mol% (total 100 mol%), the structural unit D is 50 to 80 mol%, and the structural unit E is 20 to 50 mol% (total 100 mol%). It is preferable to have it in the ratio. When the cement dispersant is composed of a water-soluble vinyl copolymer composed of the structural unit D, the structural unit E, and the structural unit F as described above, the water-soluble vinyl copolymer has the structural unit D in the molecule. Is 45 to 80 mol%, the structural unit E is 15 to 55 mol%, and the structural unit F is 5 mol% or less (total of 100 mol%), but the structural unit D is 50 to 75.5 mol. %, The structural unit E is 20 to 50 mol%, and the structural unit F is preferably 0.3 to 4.5 mol% (100 mol% in total). In any case, the water-soluble vinyl copolymer described above has a mass average molecular weight of 2000 to 70000 (GPC method, converted to pullulan, hereinafter the same), but preferably 3000 to 50000.

  The cement dispersant described above can be synthesized by a known method. For example, methods described in Japanese Patent Application Laid-Open Nos. 58-74552 and 1-2226757 can be applied.

  The drying shrinkage reducing agent used as one component of the multifunctional admixture in the preparation method of the present invention is the (poly) alkylene glycol monoalkyl ether represented by Chemical Formula 1 above. R in Chemical Formula 1 is an alkyl group having 3 to 5 carbon atoms. Examples thereof include a propyl group, an isopropyl group, a normal butyl group, an isobutyl group, a secondary butyl group, a tertiary butyl group, a pentyl group, and an isopentyl group, and among them, a normal butyl group is preferable. A in Chemical Formula 1 is a residue obtained by removing all hydroxyl groups from a (poly) alkylene glycol having a (poly) oxyalkylene group composed of only 1 to 5 oxyethylene units in the molecule. Of these, diethylene glycol monobutyl ether is preferred as the drying shrinkage reducing agent.

  The separation reducing agent used as one component of the multifunctional admixture in the preparation method of the present invention is polyvinyl alcohol synthesized from polyvinyl acetate having a saponification degree of 80 to 95 mol%, and a 4 mass% aqueous solution thereof at 20 ° C. The viscosity is 1 to 50 mPa · s. Such a separation reducing agent is used to strengthen the bubble film of entrained air and maintain the stability of the bubbles, thereby preventing a decrease in resistance to freezing and thawing due to the escape of unstable bubbles.

  The multifunctional admixture in the preparation method of the present invention is a uniform liquid in which the components of each agent are not separated even if they are mixed by mixing the cement dispersant, the drying shrinkage reducing agent and the separation reducing agent described above in a predetermined ratio. Can be used as The ratio of each agent in the multifunctional admixture is 10 to 30% by mass for the cement dispersant, 65 to 85% by mass for the drying shrinkage reducing agent, and 0.05 to 5% by mass for the separation reducing agent (total 100% by mass). The cement dispersant is 12 to 27% by mass, the drying shrinkage reducing agent is 70 to 85% by mass, and the separation reducing agent is 0.1 to 3% by mass (total 100% by mass). Is preferred. If the ratio of each agent is out of the range, the prepared low shrinkage AE concrete for civil engineering cannot satisfy the above-described plurality of requirements at the same time.

  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 Examples include alkylene alkyl ether alkyl phosphate ester salts, among which alkyl phosphate monoester salts are preferable, and octyl phosphate monoester potassium salt is more preferable. The amount of the air amount regulator used is usually 0.001 to 0.01 parts by mass per 100 parts by mass of cement.

  In the preparation method of the present invention, as the cement, in addition to various Portland cements such as ordinary Portland cement, early-strength Portland cement, medium heat Portland cement, low heat Portland cement, various types of mixed blast furnace cement, fly ash cement, silica fume cement and the like. Cement etc. can be used. Further, if necessary, it is possible to mix and use latent hydraulic substances such as fly ash, blast furnace slag fine powder and silica fume fine powder, limestone fine powder and the like. In the preparation method of the present invention, any known river sand, mountain sand, sea sand, crushed sand, etc. can be used as the fine aggregate, and any known river gravel, crushed stone, lightweight aggregate can be used as the coarse aggregate. Etc. can be used.

In the preparation method of the present invention, the cement, fine aggregate, coarse aggregate, multifunctional admixture and air amount adjusting agent described above are kneaded with water to prepare a low-shrinkage AE concrete for civil engineering. the order shall suitable for civil engineering, with cement in the range of 290~450kg / ^{m 3} (cement per AE concrete 1 m ³ to prepare) unit quantity, water / cement ratio is typically of 35% to 60% Try to be in range. The multifunctional admixture is used at a ratio of 0.3 to 1.5 parts by mass per 100 parts by mass of cement. In the preparation method of the present invention, the procedure for kneading the cement, water, fine aggregate, coarse aggregate, multifunctional admixture and air amount adjusting agent is not particularly limited, but usually the cement, fine aggregate and coarse bone are firstly used. While the material is put into a mixer and kneaded, the multifunctional admixture and the air amount adjusting agent are separately diluted with water and kneaded, and then both are kneaded to prepare a low-shrinkage AE concrete for civil engineering.

  In the preparation method of the present invention, the amount of entrained air in the low-shrinkage AE concrete for civil engineering to be prepared is 3 to 8% by volume, preferably 4 to 7% by volume. When the amount of entrained air is less than this, the bubble spacing coefficient of the cured body obtained from such a low-shrinkage AE concrete for civil engineering increases, the freeze-thaw resistance decreases, and conversely, when the amount of entrained air exceeds this, The intensity | strength of the hardening body obtained from such a low shrinkage | contraction AE concrete for civil engineering falls. The slump immediately after kneading is in the range of 6 to 15 cm, preferably in the range of 8 to 13 cm.

  In the preparation method of the present invention, as described above, cement, water, fine aggregate, coarse aggregate, multifunctional admixture and air amount adjusting agent are kneaded to prepare a low-shrinkage AE concrete for civil engineering. In this case, additives such as a setting accelerator, a setting retarder, a waterproofing agent, a preservative, and a rust preventing agent can be used in combination within the range not impairing the effects of the present invention.

The low-shrinkage AE concrete for civil engineering according to the present invention is prepared by the preparation method of the present invention described above. Among such low-shrinkage AE concretes for civil engineering, it is preferable that the obtained cured product has a drying shrinkage ratio in the range of 400 × 10 ^{−6 to} 700 × 10 ⁻⁶ , and the obtained cured product has a cell spacing coefficient of 100. What becomes the range of -300 micrometers is preferable.

  According to the present invention, when preparing a low-shrinkage AE concrete for civil engineering in which the slump immediately after kneading is kept relatively low using a multifunctional admixture for the convenience of use, 1) First, the multifunctional admixture used as a premise Is excellent in stability, 2) the flowability of the prepared low-shrinkage AE concrete for civil engineering is suppressed, and good workability is secured by suppressing a decrease in the amount of air over time, and 3) drying of the obtained cured body. Low shrinkage rate 4) Strong resistance to freeze-thaw action of the resulting cured product 5) Slow neutralization rate of the resulting cured product 6) Compressive strength of the resulting cured product correspondingly It has the effect that it is excellent and the above 1) -6) can be satisfied simultaneously.

  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 (synthesis of cement dispersant)
Synthesis of water-soluble vinyl copolymer (A-1) as a cement dispersant 60 g of methacrylic acid, 300 g of methoxypoly (23 oxyethylene units, hereinafter referred to as n = 23) ethylene glycol methacrylate and 5 g of sodium methallylsulfonate After charging 4 g of 3-mercaptopropionic acid and 490 g of water into a reaction vessel, 58 g of a 48% aqueous sodium hydroxide solution was added, and these were partially neutralized while stirring and dissolved uniformly. After the atmosphere in the reaction vessel was replaced with nitrogen, the temperature of the reaction system was maintained at 60 ° C. in a warm water bath, 25 g of a 20% aqueous solution of sodium persulfate was added to start radical polymerization reaction, and the reaction was continued for 5 hours. The reaction was terminated. Thereafter, 23 g of a 48% aqueous sodium hydroxide solution was added to completely neutralize the reaction product, thereby obtaining a 40% aqueous solution of the water-soluble vinyl copolymer (A-1). When the water-soluble vinyl copolymer (A-1) was analyzed, it was formed from a structural unit formed from sodium methacrylate / a structural unit formed from methoxypoly (n = 23) ethylene glycol methacrylate / sodium methallylsulfonate. The structural unit was a water-soluble vinyl copolymer having a mass average molecular weight of 33,800 at a ratio of 70/27/3 (mol%).

Synthesis of water-soluble vinyl copolymers (A-2) to (A-5) and (AR-1) to (AR-3) as cement dispersants Synthesis of water-soluble vinyl copolymer (A-1) In the same manner, water-soluble vinyl copolymers (A-2) to (A-5) and (a-1) to (a-3) were synthesized. Table 1 summarizes the types of water-soluble vinyl copolymers synthesized above (hereinafter also referred to as types of cement dispersants for convenience of explanation) and their contents.

In Table 1,
D-1: Structural unit formed from sodium methacrylate D-2: Structural unit formed from methacrylic acid E-1: Structural unit formed from methoxypoly (n = 23) ethylene glycol methacrylate E-2: Methoxypoly ( n = 68) structural unit formed from ethylene glycol methacrylate E-3: methoxy poly (n = 23) structural unit formed from ethylene glycol methacrylate F-1: structural unit formed from sodium methallylsulfonate F -2: Structural unit formed from sodium allyl sulfonate F-3: Structural unit formed from methyl acrylate

Test Category 2 (Preparation and evaluation of multifunctional admixture)
-Preparation of multifunctional admixture (G-1) 29 parts of cement dispersant (A-1) described in Table 1 as a cement dispersant in a glass container, 70 parts of diethylene glycol monobutyl ether (B-1) as a drying shrinkage reducing agent, As a separation reducing agent, 1 part of polyvinyl alcohol (C-1) and 100 parts of water were added and mixed to prepare a 50% aqueous solution of the multifunctional admixture (G-1).

Preparation of multifunctional admixtures (G-2) to (G-10) and (R-1) to (R-14) Multifunctional admixtures in the same manner as the preparation of multifunctional admixture (G-1) (G-2) to (G-10) and (R-1) to (R-14) were prepared. The contents of each prepared multifunctional admixture are summarized in Table 2.

Evaluation of the stability of the multifunctional admixture A 50% aqueous solution of the prepared multifunctional admixtures (G-1) to (G-10) and (R-1) to (R-14) was added to a 100 ml graduated cylinder. And the appearance of the aqueous solution was observed after being allowed to stand at room temperature for 1 week and evaluated according to the following criteria.
Evaluation criteria ○: Uniform transparency ×: Separation or turbidity is observed.

In Table 2,
A-1 to A-5, AR-1 to AR-3: Water-soluble vinyl copolymer synthesized in Test Category 1 B-1: Diethylene glycol monobutyl ether B-2: Diethylene glycol monopentyl ether B-3: Diethylene glycol monopropyl Ether BR-1: Diethylene glycol monoethyl ether BR-2: Triethylene glycol monohexyl ether BR-3: Poly (n = 7) ethylene glycol monobutyl ether C-1: Polyvinyl alcohol (trade name, manufactured by Nihon Vinegar-Poval) J-Poval JP-05, saponification degree 88 mol%, 4% aqueous solution with a viscosity of 5 mPa · s at 20 ° C.)
C-2: Polyvinyl alcohol (product name: J-Poval JP-18, manufactured by Nippon Vineyard Poval Co., saponification degree: 88 mol%, 4% aqueous solution having a viscosity of 25 mPa · s at 20 ° C.)
CR-1: Polyvinyl alcohol (trade name J-Poval JF-10, manufactured by Nippon Bibi-Poval Co., saponification degree 99 mol%, 4% aqueous solution having a viscosity of 10 mPa · s at 20 ° C.)

Test category 3 (Preparation and evaluation of low-shrinkage AE concrete for civil engineering)
-Examples 1-10 and Comparative Examples 1-14
Formulation No. described in Table 3 No. 1 to a 50-liter pan-type forced kneading mixer with ordinary Portland cement (density = 3.16 g / cm ³ , brain value 3300), fine aggregate (Iwase crushed sand, density = 2.61, FM = 2.83) and coarse aggregate (crushed stone from Iwase, density = 2.63, FM = 6.74) were sequentially added and kneaded for 15 seconds. Next, the multifunctional admixture described in Table 2 prepared in Test Category 2 and octyl phosphate as the air amount adjusting agent so that the target slump is in the range of 10 ± 1 cm and the target air amount is 4.5 ± 0.5%. Each monoester potassium salt was kneaded in a predetermined amount and diluted with water, and then added and kneaded to prepare low shrinkage AE concrete for civil engineering in each example. The contents of the prepared low shrinkage AE concrete for civil engineering are summarized in Table 4.

-Examples 11-20 and Comparative Examples 15-28
Formulation No. described in Table 3 2 in a 50-liter pan-type forced kneading mixer, ordinary Portland cement (density = 3.16 g / cm ³ , brain value 3300), fine aggregate (Iwase crushed sand, density = 2.61, FM = 2.83) and coarse aggregate (crushed stone from Iwase, density = 2.63, FM = 6.74) were sequentially added and kneaded for 15 seconds. Next, the multifunctional admixture described in Table 2 prepared in Test Category 2 and octyl phosphate as the air amount adjusting agent so that the target slump is in the range of 12 ± 1 cm and the target air amount is 4.5 ± 0.5%. Each monoester potassium salt was kneaded in a predetermined amount and diluted with water, and then added and kneaded to prepare low shrinkage AE concrete for civil engineering in each example. The contents of the prepared low shrinkage AE concrete for civil engineering are summarized in Table 5.

-Evaluation of physical properties of low-shrinkage AE concrete for civil engineering For the prepared low-shrinkage AE concrete for civil engineering, the air amount, slump, and slump residual rate were determined as follows, and the results are shown in Tables 4 and 5 below. . Moreover, about the hardened | cured material obtained from the low shrinkage | contraction AE concrete for civil engineering of each example, a drying shrinkage rate, a bubble space | interval coefficient, a freeze-thaw durability index, accelerated neutralization depth, and compressive strength were calculated | required as follows, and a result is shown. 6 and Table 7 collectively.

-Air content (volume%): Low-shrinkage AE concrete for civil engineering immediately after mixing and low-shrinkage AE concrete for civil engineering after standing for 60 minutes were measured according to JIS-A1128.
-Slump (cm): Measured according to JIS-A1101 simultaneously with the measurement of the air amount.
-Slump residual rate (%): (slump after standing for 60 minutes / slump immediately after kneading) x 100.
-Drying shrinkage ratio: According to JIS-A1129, dry shrinkage strain was measured by a comparator method for a 26-week-old specimen in which the low-shrinkage AE concrete for civil engineering in each case was stored at 20 ° C x 60% RH. Then, the drying shrinkage was determined. The smaller this value, the smaller the drying shrinkage.
・ Bubble spacing coefficient (μm): Low-shrinkage AE concrete for civil engineering of each example was stored for 26 weeks under the condition of 20 ° C. × 60% RH, and the test specimens obtained by polishing the surface of the obtained cured body The tissue was measured under a microscope according to the linear traverse method of ASTM-C457.
-Freezing and thawing durability index (300 cycles): Using the values measured according to JIS-A1148 for the low-shrinkage AE concrete for civil engineering in each example, the numerical value calculated by the durability index of ASTM-C666-75 is obtained. It was. This numerical value indicates that the maximum value is 100, and the closer to 100, the better the resistance to freezing and thawing.
-Accelerated neutralization depth (mm): For each example of low-shrinkage AE concrete for civil engineering, 10 × 10 × 40 cm square test specimens are sealed with epoxy resin on the surface, bottom and both ends, and 20 ° C. × The acceleration test was performed under the conditions of 60% RH and carbon dioxide concentration of 5%. The cross section of the specimen was cut at the age of 26 weeks, and a 1% phenolphthalein solution was sprayed to make a portion that did not turn red, a portion that did not become neutral, and a width from the outside 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 low shrinkage | contraction AE concrete for civil engineering of each example, based on JIS-A1108, it measured by material age 7 days and material age 28 days.

In Tables 4-7,
* 1: Mass parts as examples per 100 parts by mass of cement * 2: Measurement was not performed because the target fluidity (slump value) was not obtained when preparing low-shrinkage AE concrete for civil engineering.
G1 to G10 and R1 to R14: Multifunctional admixture prepared in Test Category 2 S-1: Octyl phosphate monoester potassium salt S-2: Resin acid soap-based AE agent (trade name Tupole AE manufactured by Takemoto Yushi Co., Ltd.) −300)

Claims (8)

When preparing low-shrinkage AE concrete for civil engineering using cement, water, fine aggregate, coarse aggregate, multifunctional admixture, and air amount regulator, cement is used in a unit amount of 290 to 450 kg / m ^3. and using a multi-functional admixture of the following per 100 parts by weight of cement in a ratio of 0.3 to 1.5 parts by weight, further kneading the communication line air quantity with the preparation of a slump immediately after the range of 6~15cm A method for preparing a low-shrinkage AE concrete for civil engineering, which is prepared in a range of 3 to 8 % by volume.
Multifunctional admixture: Consists of the following cement dispersant, drying shrinkage reducing agent and separation reducing agent, the cement dispersing agent being 10 to 30% by mass, the drying shrinkage reducing agent being 65 to 85% by mass and the separation reducing agent Containing 0.05 to 5% by mass (total 100% by mass) Cement dispersant: 45 to 85% by mol of the following structural unit D in the molecule, 15 to 55% by mol of the following structural unit E and the following A water-soluble vinyl copolymer having a mass average molecular weight of 2000 to 70000 having 0 to 5 mol% (100 mol% in total) of the structural unit F: Structural unit D: formed from a structural unit formed from methacrylic acid and methacrylic acid has been one selected from the structural unit or two or more structural units E: methoxypolyethylene glycol having a polyoxyethylene group composed of 7-75 oxyethylene units in the molecule Structural unit formed from tacrylate Structural unit F: One or more selected from a structural unit formed from (meth) allyl sulfonate and a structural unit formed from methyl (meth) acrylate 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 to 5 carbon atoms A: a residue obtained by removing all hydroxyl groups from a (poly) alkylene glycol having a (poly) oxyalkylene group composed of only 1 to 5 oxyethylene units in the molecule )
Separation-reducing agent: polyvinyl alcohol synthesized from polyvinyl acetate having a saponification degree of 80 to 95 mol% and a viscosity of 4% by weight aqueous solution at 20 ° C. in the range of 1 to 50 mPa · s Process for the preparation of civil engineering for low shrinkage AE concrete according to claim 1, wherein preparing the immediately following scan lamp range of 8 to 13 cm kneading. The method for preparing low-shrinkage AE concrete for civil engineering according to claim 1 or 2, wherein the amount of entrained air is adjusted to a range of 4 to 7 % by volume. The method for producing a low shrinkage AE concrete for civil engineering according to any one of claims 1 to 3 , wherein the drying shrinkage reducing agent is diethylene glycol monobutyl ether. The method for preparing a low-shrinkage AE concrete for civil engineering according to any one of claims 1 to 4 , wherein the air amount adjusting agent is an alkyl phosphate monoester salt. The low-shrinkage AE concrete for civil engineering prepared by the method for preparing low-shrinkage AE concrete for civil engineering according to any one of claims 1 to 5 . Drying shrinkage of the resulting cured ^{product, 400 × 10 -6 ~700 × 10} -6 in which the scope of the claims 6 civil engineering low shrinkage AE concrete description. The low-shrinkage AE concrete for civil engineering according to claim 6 or 7 , wherein a cell spacing coefficient of the obtained cured product is in a range of 100 to 300 µm.