JP2001302307A - Cement additive and concrete composition produced by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement additive having an excellent effect on reduction in autogeneous shrinkage of concrete even when its water-powder ratio is low. SOLUTION: This cement additive consists of: an ether compound (A) which has an oxyethylene group(s) and is represented by the formula (1) R1O(C2H4O)n1 H (wherein: R1 is a 1-4C alkyl group; and n1 is a numerical value of 1-10 on the average); and a water-soluble polymer (B) obtained by polymerizing an unsaturated ester or unsaturated ether, each having an oxyalkylene group(s), and an unsaturated carboxylic acid; wherein the ratio (A:B) of the ether compound (A) to the water-soluble polymer (B), expressed in terms of mass %, is 50:50 to 95:5. This concrete composition contains the cement additive added to a base material of the composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an additive for cement and a concrete composition using the additive.

[0002]

2. Description of the Related Art In recent years, new concrete such as high-strength concrete and high-fluidity concrete has been constructed in response to the increase in the number of building structures and labor saving of construction by high-fluidity concrete. In the production of these concretes, water and cement or water and cement and mineral fine powder (limestone fine powder,
By reducing the ratio (hereinafter referred to as water powder ratio) with blast furnace slag fine powder, fly ash, silica fume, etc., it is possible to obtain concrete with high strength or less material separation. However, in the case of concrete with a low water powder ratio, the volume decreases due to the hydration reaction of cement and fine mineral powder during the hardening process, and shrinkage occurs even under dry conditions, causing self-shrinking to cause cracking and the durability of the concrete. It has become clear that it reduces sex.

As a material for reducing this self-shrinkage, for example, "Eiichi Tazawa, Shingo Miyazawa; JSCE Proceedings No. 5"
02 Vol. 25, p. 43-, (1994)” are known.

[0004]

However, with these compounds, the effect of reducing self-shrinkage is insufficient at a low water-powder ratio, and it is difficult to provide a concrete composition having excellent durability. There was a problem.

[0005]

[In the formula, R ₁ is an alkyl group having 1 to 4 carbon atoms, and n ₁ is an average number of 1 to 10]

(B): A water-soluble polymer containing the following general formulas (2) and (3) as essential constituent units.

[Chemical 3] [In the formula, R ₂ , R ₃ and R ₄ are hydrogen or an alkyl group having 1 to 3 carbon atoms; AO is an oxyalkylene group having 2 to 4 carbon atoms and C ₂ H ₄ O having 2 carbon atoms is (AO)n; containing more than 70 wt% in _2; X is C = O or CH _2; p is an integer of 0 to 2; n ₂
Is an average of 10 to 200]

[Chemical 4] [In the formula, R ₅ , R ₆ and R ₇ are hydrogen, an alkyl group having 1 to 3 carbon atoms or (CH ₂ )kCOO(M ₂ ) _{1/m 2} ; M ₁ and M ₂ are hydrogen, alkali metal and alkaline earth. Metal, ammonia,
Alkyl group of the alkyl ammonium or 3 carbon atoms having an alkyl group of 1 to 4 carbon atoms; k is an integer of 0 to 2; valence of m ₁ M _1; m ₂ is the number of valence of M _2] more ,
0.1 to 10 parts by mass based on 100 parts by mass of cement or cement and fine powder of minerals, wherein the cement additive contains cement or cement and fine powder of minerals, water and aggregate. It is a concrete composition characterized by being.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the general formula (1) representing the compound (A) used in the cement additive of the present invention, R ₁ is a linear or branched alkyl group having 1 to 4 carbon atoms. Such groups include hydrogen, methyl group, ethyl group, n-
Propyl group, iso-propyl group, n-butyl group, is
Examples thereof include an o-butyl group and a tert-butyl group.
Of these, a methyl group and a linear or branched butyl group are particularly preferable, and when used as the cement additive of the present invention, they exhibit an excellent self-shrinkage reducing action. The general formula (1) contains an oxyethylene group. With other oxyalkylene groups such as oxypropylene group, a stable solution cannot be obtained when the water-soluble polymer (B) is mixed with water. Further, n ₁ in the general formula (1) is 1 to ₁ on average.
It is a number of 0, and preferably a number of 2 to 7. n ₁ is 1
In the range of 10 to 10, the excellent self-shrinkage reduction effect is exhibited.

The water-soluble polymer (B) used in the present invention is miscible with water at an arbitrary ratio and has the structural units represented by the general formulas (2) and (3) in its structure. It is a thing. The water-soluble polymer having this structure exhibits a self-shrinkage reducing effect in combination with (A). The constitutional unit represented by the general formula (2) is obtained by using a monomer composed of an ether or ester of an (alkoxy)polyalkylene glycol and a compound having a C=C unsaturated bond, for example, (alkoxy) Examples thereof include polyethylene glycol mono(meth)acrylic acid ester and (alkoxy)polyethylene glycol monoallyl ether.

C2 represented by AO in the general formula (2)
The oxyalkylene group of 4 to 4 is preferably an oxyethylene group, and has, for example, an oxypropylene group having 3 to 3 carbon atoms
When the oxyalkylene group of 4 and the oxyethylene group are combined, the polyoxyethylene content in the polyoxyalkylene is usually 70% by mass or more, preferably 80% by mass or more. When the content of polyoxyethylene is 70% by mass or more, the cement additive has good powder dispersibility at a low water powder ratio and excellent solution stability. Further, the oxyethylene group and the other oxyalkylene group may be polymerized in a random form, a block form, or a branched form. N ₂ in the general formula (2) is 10 on average.
The number is ~200. n ₂ is preferably 15 to 1 on average
It is a number of fifty. When n ₂ is in the range of 10 to 200,
To obtain a concrete composition that is easy to handle without delaying the setting of cement due to a synergistic effect with the compound represented by the general formula (1) and without significantly increasing the viscosity of the concrete composition. You can

The constitutional unit of the general formula (3) is obtained by using an unsaturated carboxylic acid type monomer, and examples of the unsaturated carboxylic acid type monomer include methacrylic acid, acrylic acid, crotonic acid and maleic acid. , Maleic anhydride and their alkali metal salts (sodium salt, potassium salt, etc.), alkaline earth metal salts (magnesium salt, calcium salt, etc.), ammonium salt, alkanolamine salt (diethanolamine salt, triethanolamine salt, etc.) And so on.

The water-soluble polymer (B) can be obtained by polymerizing the corresponding monomers. The constitutional unit represented by the general formula (2) and the constitutional unit represented by the general formula (3) are used. The molar ratio with the unit is preferably 1:0.5 to 1:1.
0, more preferably 1:1 to 1:7. When the molar ratio is in the range of 1:0.5 to 1:10, the fluidity of the concrete composition when the low water powder ratio is low is good.
Further, (B) may contain other structural units within a range that does not impair the fluidity and the property of reducing self-shrinkage,
Other structural units include sulfo group-containing monomers [(meth)allyl sulfonic acid, alkali metal salts and ammonium salts thereof], alkyl (meth)acrylate (alkyl having 1 to 30 carbon atoms) (methacrylic acid Methyl, methyl acrylate, etc.), aromatic hydrocarbon monomers (styrene, α-methylstyrene, etc.), amide group-containing monomers (acrylamide, N-vinylpyrrolidone, etc.)
Those obtained by using monomers such as Among these, the sulfone group-containing monomer and the aromatic hydrocarbon-based monomer are preferable. However, the general formula (2)
The total content of the structural units represented by the general formula (3) in the water-soluble polymer is preferably 50% or more, and more preferably 60 to 98%, in terms of molar ratio. Also,
As (B), a non-crosslinked type is preferable.

The method for producing the water-soluble polymer of the present invention is not particularly limited, and known methods such as JP-A-2-
Methods such as those described in Japanese Patent No. 163108 and Japanese Patent Publication No. 5-11057 can be applied. To exemplify the case of the solution polymerization method, the monomer is usually kept at 50 to 150° C. in a solvent (for example, water, isopropyl alcohol, toluene, ethylene dichloride, methyl ethyl ketone, a mixed solvent of two or more thereof). Polymerize under pressure or under pressure. For polymerization, radical polymerization initiators [persulfates (potassium persulfate, etc.), azo compounds (azobisisobutyronitrile, etc.), peroxides (benzoyl peroxide,
Dicumyl peroxide) and the like] are usually used in an amount of 0.1 to 15% by mass based on the total mass of the monomers. If necessary, chain transfer agent (sulfur-containing compounds such as lauryl mercaptan, thioglycolic acid, mercaptoethanol, etc.)
To use. The solvent used in the reaction can be distilled off if necessary.

The constitutional unit represented by the general formula (3) includes a precursor [unsaturated carboxylic acid or an anhydride thereof, a lower (C1-4) alkyl group] in addition to polymerizing the corresponding monomer. [Ester] can be polymerized and then completely or partially neutralized with an alkali metal hydroxide (NaOH, KOH, etc.), ammonia or the like, or hydrolyzed to form it. In addition, regarding the constitutional unit of the general formula (2), a precursor [in the general formula (2), a portion of —XO—(AO)n ₂ —R ₄ is a carboxylic acid or a halide (such as chloride)] It can also be formed by polymerizing and then esterifying or etherifying with (alkoxy)polyalkylene glycol.

The weight average molecular weight (based on gel permeation chromatograph/polyethylene glycol standard) of the water-soluble polymer (B) is usually 5,000 to 250,000, preferably 10,000 to 250,000. When the weight average molecular weight is 5,000 to 250,000, the fluidity of the concrete composition having a low water powder ratio is good.

The cement additive of the present invention has the general formula (1)
And a water-soluble polymer (B) having the constitutional units represented by the general formula (2) and the general formula (3) as essential constitutional units, and (A):(B) is On a mass basis,
Usually 50 to 95:50 to 5, preferably 70 to 93:3.
0 to 7. Within this range, the effect of reducing self-shrinkage, the hardening characteristics of the concrete composition and the fluidity at a low water powder ratio are good.

In the cement additive of the present invention, the mixing method of (A) and (B) is not particularly limited. (A) and (B) may be added separately to the concrete composition, or they may be mixed in advance and diluted with water to form a liquid, and then added. When used as a water diluting solution, the active ingredient content is preferably 50 to 98% by mass. Especially when premixed into one liquid, the self-shrinkage reduction effect and fluidity can be controlled at the same time by adjusting the addition amount, and since it can be added only with the existing water reducing agent measuring device, water powder It is very useful when producing concrete with different body ratios.

The concrete composition of the present invention contains the cement additive of the present invention, cement or cement and fine powder of mineral substance, water and aggregate. The cement used in the present invention is an ordinary hydraulic cement. That is, examples thereof include normal, early strength, ultrafast strength, low heat, moderate heat, sulfate resistant and white Portland cement, mixed cement, alumina cement, cement produced from incinerated ash as a raw material, and the like. Even if the concrete composition contains silica fume, fine powder such as blast furnace or waste molten slag, fine limestone powder, fly ash, mineral fine powder such as gypsum (preferably having a particle size of 0.1 μm to 300 μm). Often, the addition of these fine powders to the concrete composition is suitable, especially when producing high-fluidity concrete.

The addition amount of the cement additive of the present invention in the concrete composition is usually 0.1 to 10 parts by mass, preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of cement or cement and fine powder of mineral matter. 7 parts by mass. When the amount of the cement additive added is in the range of 0.1 to 10 parts by mass, the concrete composition has good fluidity, curability, and self-shrinkage reduction effect.

The water used in the concrete composition of the present invention is not particularly limited as long as it is one that is usually used in the production of concrete. Examples of such water include water specified in JIS A 5308 Annex 9 [tap water, water other than tap water (river water,
Lake water, well water, etc.), recovered water], etc. In the composition of the present invention, the amount of water used is such that the water powder ratio (mass ratio of water to cement and mineral fine powder: %) is 65 to 5.
An amount of 20 is preferable. Within this range, sufficient concrete strength and good workability can be obtained.

The aggregate used in the concrete composition of the present invention is not particularly limited as long as it is one generally used in the production of concrete. Examples of such aggregates include river sand, land sand, mountain sand, sea sand, crushed sand, river gravel, land gravel, mountain gravel, crushed stone, lightweight aggregate, heavy aggregate, slag aggregate, and the like. In the composition of the present invention, the amount of the aggregate in 1 m ^{3 of} concrete is not particularly limited, but for example, general river sand, land sand, mountain sand, sea sand,
For crushed sand, river gravel, land gravel, mountain gravel and crushed stone,
600-3000 kg is preferable.

The means for adding the cement additive of the present invention may be the same as in the case of the commonly used admixture for concrete. Further, other admixture materials may be contained in the concrete composition. Other admixtures include
For example, ordinary air entraining agents (AE agents) used for concrete such as resin acid salts and surfactants (polyoxyethylene alkylaryl ether etc.); known expanding agents such as calcium sulphoaluminate type and quick lime type; chloride Known curing accelerators such as calcium and triethanolamine; known retarders such as polyhydric alcohols, sugars, oxycarboxylates; known rust inhibitors such as nitrites; other known mortar or concrete admixtures, etc. , "Technology for developing concrete admixtures", published by CMC (1995)
Year). The addition amount of the other admixture material is not particularly limited, and an amount that is normally used (for example, the amount described in the above "Technology for developing concrete admixture") can be added. The method for producing the concrete composition, the method for transporting the concrete composition, the method for placing the concrete composition, the method for curing the concrete composition, and the like may be conventional methods and are not particularly limited.

[0021]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto. <Example A Production of Cement Additive> The raw materials of the cement additive used in Examples and Comparative Examples are as follows. Table 1 shows the compound (A) represented by the general formula (1) of the present invention and its comparative product (a).

[0022]

[Table 1]

General formulas (2) and (3) of the present invention
As the compound (B) having a structural unit represented by and the comparative product (b), copolymers obtained by polymerization by radical reaction using the monomers shown in Table 2 as raw materials were used. Further, the weight average molecular weight of the polymer measured by gel permeation chromatography (polyethylene glycol standard) is shown in Table 2. The cement additive was prepared by mixing the raw materials and the ratios shown in Table 3.

[0024]

[Table 2]

[0025]

[Table 3]

<Example B Concrete Production Example 1 of Concrete Composition> With the composition shown in Table 4, a high fluidity concrete was produced as a concrete composition. The target slump flow value was 65±5 cm, and the target air amount was 2±0.5% by volume.
The amount of air can be adjusted by using a commercially available air amount adjuster (Micro Air 20
2 or Micro Air 404, manufactured by NM) was used. The kneading was carried out by using a forced twin-screw mixer having a nominal capacity of 100 liters and the kneading amount was 60 liters. The kneading time was 90 seconds by adding cement, fine mineral powder, aggregate, cement additive and water. .. After kneading, JIS
A slump flow test according to A 1101, JIS A
After air amount test according to 1118, 10×10
The self-shrinkage amount was measured up to a material age of 7 days according to the method of the self-shrinkage research committee report (Japan Concrete Engineering Association 1996) using a ×40 cm mold. Furthermore, JIS A
The setting time was measured according to the method of 6204 Annex 1. The results are shown in Table 5.

[0027]

[Table 4]

[0028]

[Table 5]

Example No. 3 of the present invention. In Nos. 1 to 4, the self-shrinkage strain was small, and the initial time of setting was early.

Example C Concrete Production Example 2 of Concrete Composition Using A-2 and B-2 shown in Tables 1 and 2, concrete was produced with the composition shown in Table 6. The target slump and air volume were 18±1.5 cm and 4.5±1.0% by volume, respectively. The slump was adjusted by the addition amount of A-2, and the air amount was adjusted by using the air conditioner shown in Example B. The kneading was carried out by using a pan-type mixer having a nominal capacity of 50 liters, and the kneading amount was 35 liters. The kneading time was 60 seconds by adding cement, aggregate, cement additive and water.

[0031]

[Table 6]

Table 7 shows the test results. In Example 5, the amount of self-shrinkage strain is smaller than in Comparative Examples 6 to 8. Further, Comparative Example 9 in which the addition ratio of the compound (A) to the compound (B) was increased, and Comparative Example 10 in which the addition amount of the additive to the cement (411 kg/m ³ ) was increased ((A) 45 kg/m ³ + (B) 3.5kg/m ³ = 48.
At 5 kg/m ³ ), the concrete did not harden and the self-shrinkage strain could not be measured.

[0033]

[Table 7]

<Example D Production Example 3 of Concrete Composition> Using the cement additive E-2 shown in Table 3 of the present invention,
According to the composition of Table 8, concrete having a water cement ratio of 32 to 60 mass% was manufactured. The target slump value and air volume are 18±1.5 cm and 4.5±1.
It was 0% by volume. The slump value was adjusted by the addition amount of the cement additive E-2 so that the target slump was obtained, and the air amount was adjusted using the air conditioner described in Example B.
The mixing method and each concrete test method were the same as those described in Example B. In addition, using the specimen for which the self-shrinkage strain was measured, the length change amount was measured according to the contact gauge method described in JIS A 1129 under the environment of temperature 20°C and relative humidity 60% from 7 days to 6 months. Then, the amount of dry shrinkage strain was obtained. Total shrinkage=self shrinkage strain+dry shrinkage strain. Similarly, for comparison, concrete was also tested with only b-2 added as a cement additive, and the measured self-shrinkage strain amount and total shrinkage amount are shown in FIG.

[0035]

[Table 8]

The concrete compositions of the examples using the cement additive of the present invention were effective in reducing the self-shrinkage strain particularly in the region where the water cement ratio was low. Further, the total shrinkage strain amount including the dry shrinkage strain generated by the subsequent drying becomes 600 μm or less when producing the concrete having any water cement ratio by using the cement additive of the present invention, which is excellent concrete. became.

Further, when the fluidity is adjusted by the cement additive of the present invention, the addition amount becomes large especially at a low water powder ratio, so that the self-shrinkage reducing effect becomes large and the total shrinkage amount is reduced, and the water cement is also added. When the ratio is relatively large, the effect of reducing the drying shrinkage is also exhibited, and as a result, the durability can be made extremely excellent even in the production of concrete having different water-cement ratios.

[0038]

By using the cement additive of the present invention, it is possible to produce from concrete having a relatively high water powder ratio to high strength concrete and high fluidity concrete having a low water powder ratio. By adjusting it, it can be applied to the production of concrete with a wide range of water powder ratios. Furthermore, in using the cement additive of the present invention, it is not necessary to newly add measuring equipment to the concrete manufacturing equipment,
The existing water reducing agent measuring equipment can be used as it is. Further, the concrete composition using the cement additive of the present invention has a significantly reduced self-shrinkage strain, and moreover, the effect of effectively reducing the self-shrinkage even in the concrete having a low water powder ratio, which is said to have a large self-shrinkage. In addition, the concrete settles quickly, and the drying shrinkage is small, so the durability is extremely excellent.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a self-shrinkage strain amount and a total shrinkage amount with respect to a water cement ratio in Example D of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C04B 28/02 C04B 28/02 C08F 290/06 C08F 290/06 // C04B 103:60 C04B 103:60 111 :34 111:34 (72) Inventor Shoichi Ogawa 2-4, Daisaku, Sakura-shi, Chiba Taiheiyo Cement Co., Ltd. Central Research Institute (72) Inventor Hiroshi Hayashi 2-4-2 Daisaku, Sakura-shi, Chiba Taiheiyo Cement Central Research Institute Co., Ltd. (72) Inventor Tetsuya Yamada 1-11, Hitotsubashi Honcho, Higashiyama-ku, Kyoto Sanyo Chemical Industry Co., Ltd. (72) Inventor Fumiaki Motofuji 1-1 Sanyo Chemical Co., Ltd., Higashiyama-ku, Kyoto In-house F-term (reference) 4G012 PB31 PB36 PC11 PC14 4J027 AC02 AC06 AC07 AJ01 BA06 CA29

Claims (3)

[Claims] 1. A cement additive comprising the following (A) and (B) and having a mass% ratio of (A):(B)=50-95:50-5. (A): A compound represented by the general formula (1). R ₁ O(C ₂ H ₄ O)n ₁ H (1) [wherein, R ₁ is an alkyl group having 1 to 4 carbon atoms, n ₁ is an average of 1 to 10] (B): the following general formula A water-soluble polymer having (2) and (3) as essential constituent units. [Chemical 1] [In the formula, R ₂ , R ₃ and R ₄ are hydrogen or an alkyl group having 1 to 3 carbon atoms; AO is an oxyalkylene group having 2 to 4 carbon atoms and C ₂ H ₄ O having 2 carbon atoms is (AO)n; containing more than 70 wt% in _2; X is C = O or CH _2; p is an integer of 0 to 2; n ₂
Is an average of 10 to 200] [In the formula, R ₅ , R ₆ and R ₇ are hydrogen, an alkyl group having 1 to 3 carbon atoms or (CH ₂ )kCOO(M ₂ ) _{1/m 2} ; M ₁ and M ₂ are hydrogen, alkali metal and alkaline earth. Metal, ammonia,
Alkyl ammonium or an alkyl group having 1 to 3 carbon atoms having an alkyl group of 1 to 4 carbon atoms; k is an integer of 0 to 2; valence of m ₁ is M _1; m ₂ is the number of valence of M _2] 2. The cement additive according to claim 1, wherein the water-soluble polymer (B) has a weight average molecular weight of 5,000 to 250,000. 3. The cement additive according to claim 1 or 2, which contains cement or cement and fine powder of mineral matter, water and aggregate, and the cement additive is 100 parts by mass of cement or cement and fine powder of mineral matter. For 0.1
A concrete composition, which is 10 parts by mass.