JP4330615B2 - Cement additive and concrete - Google Patents

Description

  The present invention relates to an additive for cement and concrete, more specifically, can be efficiently produced at low cost, and can impart excellent fluidity to concrete prepared using the additive, and is excellent in a cured product obtained. The present invention relates to a cement additive capable of imparting shrinkage reduction and a concrete containing the additive.

  Conventionally, what has various carboxylic acid copolymers as a main component is proposed as an additive for cement which provides the fluidity | liquidity which was excellent in concrete (for example, refer patent documents 1-4). Moreover, as an additive for cement, not only imparting fluidity to concrete, but also imparting shrinkage reduction to the resulting cured body has been proposed (see, for example, Patent Documents 5 to 9). Furthermore, a method for producing the above cement additive without using a solvent has been proposed (see, for example, Patent Documents 10 to 12).

However, the conventionally proposed cement additives are costly mainly from the viewpoint of raw materials, and the flowability that can be imparted to the concrete prepared using the additive and the shrinkage reduction property that can be imparted to the resulting hardened body. There is a problem of being insufficient.
JP-A-57-118058 JP 63-285140 A JP 2000-72870 A JP 2003-105042 A Japanese Patent Laid-Open No. 8-268741 JP 2000-34151 A JP 2001-48620 A JP 2003-81670 A JP 2004-262715 A JP 2003-105003 A JP 2005-0294769 A JP 2005-132955 A

  The problem to be solved by the present invention is that it can be efficiently produced at low cost, and can impart excellent fluidity to concrete prepared using the same, and impart excellent shrinkage reduction to the resulting cured body The present invention provides a cement additive and a concrete containing the same.

  Accordingly, as a result of studies conducted by the present inventors to solve the above-mentioned problems, it is correctly and appropriately used as a cement additive that a specific carboxylic acid copolymer composition obtained through a predetermined process is used. I found.

  That is, the present invention relates to a cement additive comprising a carboxylic acid copolymer composition obtained through the following first step and second step.

  First step: Monomer represented by the following chemical formula 1 and / or a monomer represented by the chemical formula 2 shown below and / or a monomer having the peroxide value of 5.0 meq / kg or less and purified. And a monomer represented by (Chemical Formula 1 and monomer represented by Chemical Formula 2) / Chemical Formula 3 = 70/30 A radically polymerizable monomer mixture containing at a ratio of ˜45 / 55 (molar ratio) is subjected to radical polymerization reaction in the presence of an organic peroxide radical polymerization initiator without using a solvent, and is subjected to mass average molecular weight. A step of obtaining a carboxylic acid ester copolymer of 3500 to 70000.

  Second step: Neutralizing salt of carboxylic acid copolymer having a mass average molecular weight of 3000 to 60000 and polyethylene produced by hydrolyzing the carboxylic acid ester copolymer obtained in the first step with a basic compound. A step of obtaining a carboxylic acid copolymer composition comprising glycol monoalkyl ether.

In Chemical Formulas 1 to 3,
R ¹ , R ² , R ³ : an alkyl group having 3 to 5 carbon atoms p, q, r: an integer of 1 to 5 A: only 2 to 150 oxyethylene units or a total of 2 to 150 oxyethylene units Residues obtained by removing all hydroxyl groups from polyalkylene glycol having a polyoxyalkylene group composed of oxypropylene units

  The cement additive according to the present invention comprises a carboxylic acid copolymer composition obtained through the first step and the second step.

First, the first step will be described. In the first step, a radically polymerizable monomer mixture composed of the monomer represented by Chemical Formula 1 and / or the compound represented by Chemical Formula 2 and the compound represented by Chemical Formula 3 is used without using a solvent. In the presence of a polymerization initiator, a radical polymerization reaction is performed to obtain a carboxylic acid ester copolymer. In the monomer represented by Chemical Formula ¹ , R ¹ includes 1) an alkyl group having 3 carbon atoms such as a normal propyl group and an isopropyl group, and 2) a normal butyl group, an isobutyl group, a secondary butyl group, a tertiary butyl group, and the like. And an alkyl group having 5 carbon atoms such as a normal pentyl group, an isopentyl group, and a neopentyl group. Among them, a normal butyl group is preferable. Moreover, although it is set as the integer of p1-5, 2 or 3 is preferable.

  The monomers represented by Chemical Formula 1 include normal propyl diethylene glycol monomaleate, isopropyl triethylene glycol monomaleate, normal butyl diethylene glycol monomaleate, normal butyl triethylene glycol monomaleate, and normal butyl pentaethylene glycol monomaleate. , Isobutyl diethylene glycol monomaleate, normal pentyl tetraethylene glycol monomaleate, isopentyl triethylene glycol monomaleate, neopentyl diethylene glycol monomaleate, normal propyl diethylene glycol monofumarate, normal butyl diethylene glycol monofumarate, normal butyl triethylene Glycol monofumarate, normal pentyl tetrae Glycol mono fumarate, isopentanol tilt triethylene glycol monomethyl fumarate, and the like.

In the monomer represented by Chemical Formula ² , R ² and R ³ are the same as those described above for R ^{1 in} Chemical Formula ¹ . Q and r are the same as described above for p in Chemical Formula 1. As the monomer represented by Chemical Formula 2, bis- (normal propyl diethylene glycol) maleate, bis- (normal butyl diethylene glycol) maleate, bis- (normal butyl triethylene glycol) maleate, bis- (normal pentyl diethylene glycol) maleate, bis Examples include-(normal pentyl tetraethylene glycol) maleate, bis- (normal butyl diethylene glycol) fumarate, bis- (normal propyl triethylene glycol) fumarate, bis- (normal pentyl diethylene glycol) fumarate, and the like.

  In the monomer represented by Chemical Formula 3, A in Chemical Formula 3 includes 1) a residue obtained by removing all hydroxyl groups from polyethylene glycol in which the oxyalkylene unit is composed solely of oxyethylene units, and 2) the oxyalkylene unit is an oxyethylene unit. And a residue obtained by removing all hydroxyl groups from (poly) ethylene (poly) propylene glycol consisting of both oxypropylene units and 1) is preferred. In the case of 2), the bonding mode of the oxyethylene unit and the oxypropylene unit may be either a random bond or a block bond. The number of repeating oxyalkylene units constituting A is 2 to 150, preferably 10 to 90. Examples of the monomer represented by Chemical Formula 3 include 1) α-allyl-ω-hydroxy-polyoxyethylene, and 2) α-allyl-ω-hydroxy- (poly) oxyethylene (poly) oxypropylene.

  The monomer represented by Chemical Formula 3 described above has a peroxide value of 5.0 meq / kg or less, preferably 2.0 meq / kg or less, more preferably 0.1 to 1.0 meq / kg. Is used. The monomer represented by Chemical Formula 3 is α-allyl-ω-hydroxy-polyoxyalkylene, which is obtained by subjecting the corresponding allyl alcohol to ring-opening addition reaction of alkylene oxide, and obtained by such ring-opening addition reaction. In the α-allyl-ω-hydroxy-polyoxyalkylene obtained, peroxide remains as a by-product due to the reaction conditions during the ring-opening addition reaction and the purification conditions after the ring-opening addition reaction. Depending on the conditions of the time, the same peroxide remains as a by-product. When the peroxide value exceeds 5.0 meq / kg, such α-allyl-ω-hydroxy-polyoxyalkylene is converted into a monomer represented by Chemical Formula 1 and / or a monomer represented by Chemical Formula 2 A high-quality carboxylic acid copolymer cannot be obtained even if a radical polymerization reaction is carried out without using a solvent. Therefore, in the present invention, α-allyl- represented by Chemical Formula 3 wherein the peroxide value is 5.0 meq / kg or less, preferably 2.0 meq / kg or less, more preferably 0.1 to 1.0 meq / kg. The ω-hydroxy-polyoxyalkylene is subjected to a radical polymerization reaction. Here, the peroxide value (meq / kg) is a value measured according to the method described in the standard oil analysis test method (I) (1996 version) established by the Japan Oil Chemists' Society.

  Examples of the purification treatment method for reducing the peroxide value include 1) a method using an adsorbent, 2) a method using a reducing agent, 3) a neutralizing method, and the like. preferable. There are various types of such adsorbents, such as aluminum oxide adsorbents, magnesium oxide adsorbents, aluminum oxide / magnesium oxide adsorbents, silicic acid / aluminum oxide adsorbents, silicic acid / magnesium oxide adsorbents, etc. In any case, it is preferable to use an adsorbent containing aluminum oxide and / or magnesium oxide. In addition, various types of purification methods using such an adsorbent can be mentioned, and an α-allyl-ω-hydroxy-polyoxyalkylene having a peroxide value exceeding 3.0 meq / kg is brought into contact with the adsorbent under heating. The method of making it preferable is. For example, α-allyl-ω-hydroxy-polyoxyalkylene having a peroxide value exceeding 3.0 meq / kg is mixed with an adsorbent under heating at around 100 ° C., and then the mixture is subjected to pressure filtration and filtrate. As a result, α-allyl-ω-hydroxy-polyoxyalkylene purified to a peroxide value of 3.0 meq / kg or less is obtained.

  In the first step, a radical containing 100 mol% of the monomer represented by Chemical Formula 1 and / or the monomer represented by Chemical Formula 2 and the monomer represented by Chemical Formula 3 as described above. The polymerizable monomer mixture is subjected to a radical polymerization reaction. Such a radical polymerizable monomer mixture is (total of monomer represented by Chemical Formula 1 and monomer represented by Chemical Formula 2) / monomer represented by Chemical Formula 3 = 70/30 to 45/55 ( (Molar ratio) in the ratio of (monomer represented by Chemical Formula 1 and monomer represented by Chemical Formula 2) / monomer represented by Chemical Formula 3 = 65 / 35-50 It is preferable to contain at a ratio of / 50 (molar ratio). Here, when both the monomer represented by Chemical Formula 1 and the monomer represented by Chemical Formula 2 are used, it is preferable that the mass ratio of the monomer represented by Chemical Formula 1 is large.

  In the first step, radical polymerization containing 100 mol% of the monomer represented by Chemical Formula 1 and / or the monomer represented by Chemical Formula 2 and the monomer represented by Chemical Formula 3 as described above. The radical monomer mixture is subjected to a radical polymerization reaction in the presence of a radical polymerization initiator without using a solvent. The radical polymerization initiator used here is an organic peroxide radical polymerization initiator. Among these, those that are active at high temperatures, have high solubility in the radical polymerization reaction system, and are liquid at room temperature are preferable. This includes, for example, 1) tertiary butyl peroxyneooctanoate, tertiary butyl peroxyneohexanoate, tertiary butyl peroxypivalate, tertiary butyl-2-ethylhexanate, tertiary butyl peroxyiso Peroxyesters such as butyrate, tertiary butyl peroxylaurate, tertiary butyl peroxy-2-ethyl hexanate, tertiary butyl peroxybenzoate, 2) isobutyryl peroxide, 3,3,5-trimethyl Diacyl peroxides such as hexanoyl peroxide, 3) Dialkyl peroxides such as di-tertiary butyl peroxide, tertiary butyl cumyl peroxide, 4) Di-2-ethylhexyl peroxydicarbonate, di-methoxy Peroxydicarbonates such as butylperoxydicarbonate 5) Peroxyketals such as 1,1-bis (tertiarybutylperoxy) cyclohexane, 2,2-bis (tertiarybutylperoxy) butane Among them, industrially general-purpose tertiary butyl peroxybenzoate and di-tertiary butyl peroxide are preferable. The organic peroxide radical polymerization initiator is usually preferably used in an amount of 0.5 to 5 parts by mass with respect to 100 parts by mass of the radical polymerizable monomer mixture.

  In the first step, the radical polymerizable monomer mixture as described above is subjected to a radical polymerization reaction in the presence of an organic peroxide radical polymerization initiator without using a solvent to obtain a mass average molecular weight of 3500. A carboxylic acid ester copolymer of 70000, preferably 3500-60000 is obtained. Here, the mass average molecular weight is a mass average molecular weight in terms of pullulan as determined by gel permeation chromatography.

  In the first step, for example, a radical polymerizable monomer mixture is charged into a reaction can, and an organic peroxide radical polymerization initiator is added thereto in a nitrogen atmosphere, and radical polymerization is performed at 90 to 150 ° C. for 6 to 12 hours. Reaction is carried out to obtain a carboxylic acid ester copolymer.

  Next, the second step will be described. In the second step, the carboxylic acid ester copolymer obtained in the first step is hydrolyzed with a basic compound, and the resulting neutralized salt of the carboxylic acid copolymer, polyethylene glycol monoalkyl ether, A carboxylic acid copolymer composition is obtained.

  The basic compounds used in the second step are 1) alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, 2) alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, and 3) ammonia. And amines such as triethanolamine, among which sodium hydroxide is preferable.

In the second step, the carboxylic acid copolymer composition obtained by the hydrolysis treatment is obtained by 1) completely hydrolyzing the carboxylic acid ester copolymer obtained in the first step, and the carboxylic acid copolymer produced thereby. Comprising completely neutralized salt of polymer and polyethylene glycol monoalkyl ether, 2) Carboxylic acid copolymer produced by partially hydrolyzing carboxylic acid ester copolymer obtained in the first step 3) and a mixture of 1) and 2). In the second step, the neutralized salt of the carboxylic acid copolymer contained in the carboxylic acid copolymer composition preferably has a hydrolysis rate of 95% or more. Here hydrolysis rate, K ¹ ester bond number contained in the carboxylic acid ester ^copolymer, when an ester bond number contained in the carboxylic acid copolymer was ^{K 2, {(K 1 -K} 2) / K ¹ } × 100.

  In the second step, the neutralized salt or partially neutralized salt of the carboxylic acid copolymer obtained by hydrolyzing the carboxylic acid ester copolymer described above has a mass average molecular weight of 3000 to 60000. Is preferably 3500 to 50000.

  The additive for cement according to the present invention comprises a carboxylic acid copolymer composition obtained through the first step and the second step as described above. The cement additive according to the present invention can be applied to the preparation of hydraulic cement materials such as cement paste, mortar, concrete, etc., but the effect is most prominent when used for the preparation of concrete. . Concrete is prepared from cement, fine aggregate, coarse aggregate, water, etc. As the cement used for its preparation, in addition to various Portland cements such as ordinary Portland cement, early-strength Portland cement, moderately hot Portland cement, etc. , Various mixed cements such as blast furnace cement, fly ash cement, silica fume cement and the like, and fine aggregates include river sand, mountain sand, sea sand, crushed sand and the like, and coarse aggregates include river gravel, Examples include crushed stone and lightweight aggregate.

  When preparing concrete using the cement additive according to the present invention, the cement additive according to the present invention is usually 0.1 to 3 parts by mass, preferably 0, per 100 parts by mass of cement. The ratio is 15 to 2 parts by mass. When the additive for cement according to the present invention is used for the preparation of ordinary strength concrete (usually having a water / cement ratio of 45% or more), it is possible to prepare a material excellent in fluidity and drying shrinkage reduction, When used for the preparation of high-strength concrete (usually having a water / cement ratio of 40% or less), it is possible to prepare a material excellent in fluidity and self-shrinkage reduction.

  Additives for cement according to the present invention are within the range not impairing the effects of the present invention, other than air amount adjusting agent, setting accelerator, setting retarder, waterproofing agent, preservative, rust inhibitor, etc. These additives can be used in combination.

  The additive for cement according to the present invention can be efficiently produced at a low cost, and imparts excellent fluidity to concrete prepared using the additive, and at the same time imparts excellent shrinkage reduction to a cured product obtained.

  Hereinafter, in order to make the configuration and effects of the present invention more specific, examples and the like will be given. In the following Examples and Comparative Examples, “part” means “part by mass” and “%” means “% by mass”.

Test Category 1 (Synthesis of carboxylic acid copolymer composition as an additive for cement)
Example 1 {Synthesis of carboxylic acid copolymer composition (P-1)}
260 g (1.0 mol) of normal butyl diethylene glycol monomaleate, α-allyl-ω-hydroxy-polyoxyethylene purified with a peroxide value of 0.4 meq / kg (repeat number of oxyethylene units 33, hereinafter n = 33) (referred to as 33) was charged in a reaction vessel and dissolved uniformly with stirring, and the atmosphere was replaced with nitrogen. The temperature of the reaction system was kept at 120 ° C., and 16.5 g of tertiary butyl peroxybenzoate was added to initiate radical polymerization reaction. After the lapse of 5 hours, 16.5 g of tertiary butyl peroxybenzoate was further added, and a radical polymerization reaction was performed at a temperature of 120 to 130 ° C. for 4 hours to complete the radical polymerization reaction. When the obtained copolymer was analyzed, it was a carboxylic acid ester copolymer having a mass average molecular weight of 42200 (first step). Next, 1523 g of water was gradually added and mixed with 1684 g of this carboxylic acid ester copolymer, and further hydrolyzed at about 60 ° C. for 4 hours while gradually adding 240 g (1.8 mol) of 30% aqueous sodium hydroxide solution. Was done. When the obtained reaction mixture was analyzed, it was 3447 g of a 50% aqueous solution of a carboxylic acid copolymer composition (P-1) comprising a neutralized salt of a carboxylic acid copolymer and normal butyldiethylene glycol, and a hydrolysis rate of 100 %, The weight average molecular weight of the neutralized salt of the carboxylic acid copolymer was 37900 (second step).

Examples 2 to 14 and Comparative Examples 1 to 7 {Synthesis of carboxylic acid copolymer compositions (P-1) to (P-14) and (R-1) to (R-7)}
In the same manner as the carboxylic acid copolymer composition (P-1) of Example 1, the carboxylic acid copolymer compositions (P-2) to (P-14) of Examples 2 to 14 and Comparative Examples 1 to 7 were used. ) And (R-1) to (R-7) were synthesized. Table 1 summarizes the contents of monomers and the like used in the synthesis of the carboxylic acid copolymer compositions of the above examples.

Reference Example 1 {Synthesis of product (r-1)}
Normal butyl diethylene glycol monomaleate 260 g (1.0 mol), α-allyl-ω-hydroxy-polyoxyethylene (n = 33) 1240 g (0.82 mol) purified to a peroxide value of 0.4 meq / kg Was uniformly dissolved while stirring, and the atmosphere was replaced with nitrogen. The temperature of the reaction system was kept at 80 ° C., and 8 g of azobisisobutyronitrile was added to initiate radical polymerization reaction. Two hours later, 8 g of azobisisobutyronitrile was further added to carry out radical polymerization reaction for 3 hours, and 10 g of azobisisobutyronitrile was further added, and the temperature of the reaction system was maintained at 90 to 100 ° C. A time radical polymerization reaction was performed to obtain a reaction mixture. When the obtained reaction mixture was analyzed, most of them were raw material monomers, and the polymerization reaction was only partially progressed. For this reason, it did not perform a hydrolysis process and this was made into the product (r-1).

Reference Example 2 {Synthesis of product (r-2)}
A reaction vessel was charged with 98 g (1.0 mol) of maleic anhydride and 770 g (0.82 mol) of α-allyl-ω-hydroxy-polyoxyethylene (n = 20) purified to a peroxide value of 0.3 meq / kg. The solution was uniformly dissolved with stirring, and the atmosphere was replaced with nitrogen. The temperature of the reaction system was kept at 110 ° C., and 3 g of tertiary butyl peroxybenzoate was added to initiate radical polymerization reaction. After the start of the reaction, the viscosity of the reaction system greatly increased and gelled, so the reaction was stopped midway. The obtained gelled product was taken as a product (r-2).

In Table 1,
* 1: Peroxide value (meq / kg)
* 2: Amount of radical initiator used relative to 100 parts of radical polymerizable monomer mixture (parts)
* 3: Type of hydrolyzing agent * 4: Amount of hydrolyzing agent used (parts)
* 5: Weight average molecular weight of neutralized salt of carboxylic acid copolymer produced by hydrolysis treatment * 6: Measurement or treatment was not performed because no copolymer was obtained.

E-1: normal butyl diethylene glycol monomaleate (R ^{1 in} chemical formula ¹ is normal butyl group, p is 2)
E-2: normal butyl triethylene glycol monomaleate (R ^{1 in} chemical formula ¹ is normal butyl group, p is 3)
E-3: normal butyl diethylene glycol monofumarate (R ^{1 in} chemical formula ¹ is normal butyl group, p is 2)
E-4: normal butyl triethylene glycol monofumarate (R ^{1 in} chemical formula ¹ is normal butyl group, p is 3)
E-5: Normal propyl diethylene glycol monomaleate (R ^{1 in} Chemical Formula ¹ is a normal propyl group, p is 1)
E-6: Isobutyl diethylene glycol monomaleate (R ^{1 in} chemical formula ¹ is an isobutyl group, p is 2)
E-7: Neopentyl diethylene glycol monomaleate (R ^{1 in} chemical formula ¹ is a neopentyl group, p is 2)
E-8: normal butyl pentaethylene glycol monomaleate (R ^{1 in} chemical formula ¹ is normal butyl group, p is 7)
E-9: Bis- (normal butyl diethylene glycol) maleate (R ² and R ^{3 in} Chemical Formula 2 are normal butyl groups, q and r are 2)
E-10: Bis- (normal pentyl diethylene glycol) maleate (in formula 2, R ² and R ³ are normal pentyl groups, q and r are 2)
E-11: E-1 / E-10 = 90/10 (mass ratio) mixture E-12: E-3 / E-9 = 80/20 (mass ratio) mixture E-13: E-1 / E-9 = 80/20 (mass ratio) mixture e-1: normal butyl heptaethylene glycol monomaleate (R ^{1 in} chemical formula ¹ is normal butyl group, p is 7)
e-2: normal octyl tetraethylene glycol monomaleate (R ^{1 in} chemical formula ¹ is normal octyl group, p is 4)
h-1: maleic anhydride

F-1: α-Allyl-ω-hydroxy-polyoxyethylene (n = 33)
F-2: α-allyl-ω-hydroxy-polyoxyethylene (n = 20)
F-3: α-allyl-ω-hydroxy-polyoxyethylene (n = 68)
F-4: α-allyl-ω-hydroxy-polyoxyethylene (n = 80) polyoxypropylene (the number of repeating oxypropylene units is 5)
F-5: α-allyl-ω-hydroxy-polyoxyethylene (n = 8)
F-6: α-allyl-ω-hydroxy-polyoxyethylene (n = 120)
f-1: α-allyl-ω-hydroxy-polyoxyethylene (n = 160)
f-2: α-allyl-ω-hydroxy-oxyethylene (n = 1)
G-1: Tertiary butyl peroxybenzoate G-2: Ditertiary butyl peroxide g-1: Azobisisobutyronitrile J-1: Sodium hydroxide J-2: Potassium hydroxide

Test category 2 (Preparation and evaluation of concrete)
-Preparation of concrete Concrete was prepared under the blending conditions described in Table 2. Compound No. In the preparation of the normal strength concrete of No. 1, a 50 liter pan-type forced kneading mixer is mixed with ordinary Portland cement (specific gravity = 3.16, brain value 3300), fine aggregate (Oikawa water sand, specific gravity = 2.58) and Coarse aggregates (Okazaki crushed stone, specific gravity = 2.68) were sequentially added and air-kneaded for 15 seconds. Next, an additive for cement and air composed of the carboxylic acid copolymer composition shown in Table 1 synthesized in the test category 1 so that the target slump is 18 ± 1 cm and the target air amount is in the range of 4 to 5%. The amount adjusting agent was kneaded and added together with water, and kneaded to prepare concrete for each example. Also, the formulation No. In the preparation of high-strength concrete of No. 2, using the same material as described above, it is sequentially put into a 50 liter pan-type forced kneading mixer and kneaded for 15 seconds, with a target slump of 22 ± 1 cm and a target air volume of 2 Add the cement additive and air amount regulator composed of the carboxylic acid copolymer composition shown in Table 1 synthesized in the above test category 1 and mix with water so that it is in the range of ~ 3%. Concrete was prepared. Note that AE-300 manufactured by Takemoto Yushi Co., Ltd. was used as the air amount regulator.

-Physical property evaluation of concrete About the prepared concrete of each example, slump, slump residual rate, air content, drying shrinkage rate, self-shrinkage rate, and compressive strength were calculated | required as follows, and the result was shown in Tables 3-6.

-Slump: It measured based on JIS-A1150 simultaneously with the measurement of the air amount mentioned later.
-Slump residual rate: (slump after standing for 90 minutes / slump just after mixing) x 100.
Air amount: Measured according to JIS-A1128 immediately after kneading and after standing for 90 minutes.
-Drying shrinkage ratio: Based on JIS-A1128, the specimen after the age of 26 weeks which stored the concrete of each example under the humidity control of 20 degreeC x 60% RH was measured by the comparator method. It shows that drying shrinkage is so small that a numerical value is small.
-Self-shrinkage rate: Specimen 28 days after the start of setting in accordance with the "Concrete self-shrinkage stress test method (draft)" described in the report of the Japan Concrete Institute's Self-Shrink Research Committee The self-shrinkage strain was measured. The age of the starting time was the first setting time. It shows that self-contraction is so small that a numerical value is small.
-Compressive strength: Based on JIS-A1108, material age 7 days and material age 28 days were measured.

In Table 3,
Addition amount: Addition part in terms of solid content such as carboxylic acid copolymer composition per 100 parts of cement * 7: Polycarboxylic acid cement dispersant (trade name Tupol HP-11 manufactured by Takemoto Yushi Co., Ltd.)
* 8: A copolymer of maleic acid and α-allyl-ω-hydroxy-polyoxyethylene (n = 20) in a 50/50 (molar ratio) aqueous system (mass average molecular weight 18600)

In Table 4,
* 9: Measurement was not performed because the target slump could not be obtained due to insufficient fluidity even when the amount of the carboxylic acid copolymer composition added was increased.

In Table 5,
Self-shrinkage: In the case of normal strength concrete, self-shrinkage was originally small, so it was not measured

Drying shrinkage: In the case of high-strength concrete, the drying shrinkage was originally small, so it was not measured * 10: Not measured because the specimen was not obtained

Claims (10)

A cement additive comprising a carboxylic acid copolymer composition obtained through the following first step and second step.
First step: Monomer represented by the following chemical formula 1 and / or a monomer represented by the chemical formula 2 shown below and / or a monomer having the peroxide value of 5.0 meq / kg or less and purified. And a monomer represented by (Chemical Formula 1 and monomer represented by Chemical Formula 2) / Chemical Formula 3 = 70/30 A radically polymerizable monomer mixture containing at a ratio of ˜45 / 55 (molar ratio) is subjected to radical polymerization reaction in the presence of an organic peroxide radical polymerization initiator without using a solvent, and is subjected to mass average molecular weight. A step of obtaining a carboxylic acid ester copolymer of 3500 to 70000.
Second step: Neutralizing salt of carboxylic acid copolymer having a mass average molecular weight of 3000 to 60000 and polyethylene produced by hydrolyzing the carboxylic acid ester copolymer obtained in the first step with a basic compound. A step of obtaining a carboxylic acid copolymer composition comprising glycol monoalkyl ether.

(In Chemical Formulas 1 through 3,
R ¹ , R ² , R ³ : an alkyl group having 3 to 5 carbon atoms p, q, r: an integer of 1 to 5 A: only 2 to 150 oxyethylene units or a total of 2 to 150 oxyethylene units A residue obtained by removing all hydroxyl groups from a polyalkylene glycol having a polyoxyalkylene group composed of oxypropylene units) The monomer represented by Chemical Formula ¹ is a monomer in the case where R ^{1 in} Chemical Formula ¹ is a normal butyl group and p is 2 or 3, and the monomer represented by Chemical Formula 2 is The additive for cement according to claim 1, wherein R ² and R ³ in said group are normal butyl groups and q and r are 2 or 3.   The additive for cement according to claim 1 or 2, wherein the monomer represented by Chemical Formula 3 is one obtained by purifying the peroxide value to 0.1 to 1.0 meq / kg.   When the monomer represented by Chemical Formula 3 is a residue obtained by removing all hydroxyl groups from polyethylene glycol having a polyoxyethylene group in which A in Chemical Formula 3 is composed of only 10 to 90 oxyethylene units The additive for cement according to any one of claims 1 to 3, wherein the additive is used.   The radical polymerizable monomer mixture in the first step is (total of the monomer represented by Chemical Formula 1 and the monomer represented by Chemical Formula 2) / monomer represented by Chemical Formula 3 = 65 / 35-50 The additive for cement according to any one of claims 1 to 4, which is contained at a ratio of / 50 (molar ratio).   The cement additive according to any one of claims 1 to 5, wherein the organic peroxide radical polymerization initiator is tertiary butyl peroxybenzoate.   The additive for cement according to any one of claims 1 to 6, wherein the basic compound in the second step is sodium hydroxide.   The cement additive according to any one of claims 1 to 7, wherein the carboxylic acid copolymer in the second step has a mass average molecular weight of 3500 to 50000.   The additive for cement according to any one of claims 1 to 8, wherein the neutralized product of the carboxylic acid copolymer in the second step has a hydrolysis rate of 95% or more. Concrete containing 0.1 to 3 parts by mass of the cement additive according to any one of claims 1 to 9 per 100 parts by mass of cement.