KR100668942B1 - Cement admixture and method for preparing the same - Google Patents

Abstract

The present invention relates to a cement admixture and a method for preparing the same, and the present invention is prepared by blending an acrylic acid copolymer and a polyalkylene glycol ester polycarboxylic acid fluidizing agent containing a reactive surfactant as a unit monomer. It provides a method for producing a cement admixture.

In another aspect, the present invention provides a cement admixture, which is produced by the above production method.

In addition, the present invention a) 100 parts by weight of cement; And b) 0.01 to 10 parts by weight of the cement admixture provides a cement composition comprising.

The cement admixture prepared by the method of preparing the cement admixture of the present invention can improve the dispersibility of cement particles than the conventional cement admixture, and improve the initial susceptibility by the excellent initial dispersibility, while the fluidity of the cement composition even in the region of high susceptibility. It is possible to increase the flow rate, prevent the decrease in the obtained fluidity over time, and maintain high fluidity.

In addition, when the cement admixture of the present invention is used, the concrete slump value is excellent, the slump holding force is high, and the air amount is lower than that of the conventional polycarboxylic acid-based fluidizing agent, and it is possible to give excellent working stability than the conventional cement admixture.

Cement Admixtures, Acrylic Acid Copolymers, Reactive Surfactants, Polyalkylene Glycol Ester Polycarboxylic Acid Glidants

Description

Cement admixture and preparation method thereof {Cement admixture and method for preparing the same}

The present invention relates to a cement admixture and a method for manufacturing the same, and more particularly, to improve the dispersibility of cement particles, to improve the flowability of the cement composition even in the region of high susceptibility, to obtain a high concrete slump value, The present invention relates to a cement admixture capable of maintaining excellent slump value and lowering air volume as compared with a conventional polycarboxylic acid-based fluidizing agent, thereby providing good workability to the cement composition and improving compressive strength.

Cement compositions, such as concrete or mortar, are hydraulic reactants that are cured by the reaction of cement and water, and have different physical properties such as compressive strength after curing depending on the amount of water used. In general, an increase in the amount of water used improves workability, while lowering compressive strength and causing cracks, so that the amount of water used for the cement composition is limited, and according to Korean Industrial Standard KS F 2560 to reduce the amount of water used. As will be described later, a chemical admixture for concrete is used.

The chemical admixtures for concrete are roughly classified into air entraining admixtures, water reducing admixtures, and high range water reducing admixtures. In addition, AE, which is a chemical admixture used in cement compositions to increase the amount of fine air, is mixed with a water reducing agent or a high performance water reducing agent and classified into an air entraining and water reducing admixture and a high performance AE water reducing agent. The ability of the AE water reducing agent to reduce water can reduce the amount of water used by 10% by weight compared to not using, and the high performance AE water reducing agent can reduce the amount of water used by more than 18% by weight.

Current high performance AE water reducing agents include naphthalene sulfonic acid formaldehyde condensate salts (naphthalene-based), melamine sulfonic acid formaldehyde condensate salts (melamine-based), polycarboxylic acid salts (polycarboxylic acid-based), and the like. Each of these high performance AE sensitizers has excellent features while also having problems. For example, naphthalene and melamine have excellent curing properties but have problems in flow retention (slump loss). On the other hand, the polycarboxylic acid system has a problem of high curing delay. However, with the development of a polycarboxylic acid-based concrete admixture having excellent fluidity, it is possible to obtain good fluidity even with a small amount of addition, and the problem of curing delay has been improved. .

In recent years, due to the rapid development of the industrial society, the increase in the size and the height of the building structure has increased the use of a pressure pump to facilitate the transport and placement of concrete during construction.

However, this concrete has a very low workability, which causes frequent problems such as clogging of the pump and excessive energy consumption. Therefore, an excess water is added to the concrete to improve the fluidity. By increasing the workability at the time of transport and pouring, in this case, the strength of the hardened concrete is lowered, which causes a serious adverse effect on the durability of the concrete.

In order to prevent the above problems, namely, to reduce the strength characteristics due to excessive moisture added during concrete production, the concrete is part of a method for simultaneously satisfying the strength characteristics and workability by reducing the number of units contained in the concrete. At the appropriate time during the manufacturing process, a fluidizing agent compound classified into organic acid compounds such as lignin-based, naphthalene-based, melamine-based or iminosulfonic acid-based compounds was selected as necessary and mixed with concrete.

However, in the case of the conventional lignin-based, naphthalene-based, melamine-based or organic acid-based compounds listed above, the susceptibility effect is not so great and the susceptibility is not easy to control. Not only that, but the amount of addition causes problems such as poor cement hardening properties.

In addition, the above-described polymers such as naphthalene and melamine are adsorbed to cement particles used as binders in the manufacture of concrete. Since such cement particles are fine particles having a great activity of hydration reaction with time, they are used as the surface of cement particles. Since the adsorbed polymer material becomes entangled with the hydrate and thus becomes electrically neutral, the electrostatic repulsive force and the three-dimensional repulsive force are lowered and the balance is destroyed, so that the van der Waals attraction prevails and the slumping phenomenon begins to deepen. As a result, not only the dispersibility of the cement particles is lowered, but also there is a problem that seriously affects the strength of concrete after curing.

Currently, in the concrete industry, since concrete is mainly used for building concrete pouring and structures, the fluidity of the concrete composition is strongly required to give ease of work. Among them, naphthalene sulfonic acid-based fluidizing agents do not have sufficient slump retention with time, and have a problem in that a fluidizing agent must be blended immediately before concrete pouring, and durability and strength of the concrete building are decreased after using the fluidizing agent.

In order to solve the above problems, the present invention has better fluidity and concrete slump value of the cement composition than the conventional cement admixture, high fluidity holding force and slump retention force, and low air volume compared to the conventional polycarboxylic acid type fluidizing agent. An object of the present invention is to provide a cement admixture having excellent work stability and a method for producing the same.

In order to achieve the above object, the present invention provides a method for preparing a cement admixture, which is prepared by blending an acrylic acid copolymer and a polyalkylene glycol ester polycarboxylic acid fluidizing agent containing a reactive surfactant as a unit monomer. to provide.                     

In another aspect, the present invention provides a cement admixture, which is produced by the above production method.

In addition, the present invention a) 100 parts by weight of cement; And b) 0.01 to 10 parts by weight of the cement admixture provides a cement composition comprising.

Hereinafter, the present invention will be described in detail.

The acrylic acid copolymer containing the reactive surfactant as a unit monomer

a) 45 to 90% by weight of a (meth) acrylic acid monomer or salt thereof represented by Formula 1; And

b) Preferred is a copolymer comprising 0.5 to 40% by weight of a reactive surfactant represented by the following formula (2).

[Formula 1]

[Formula 2]

In Chemical Formula 1,

R ¹ is hydrogen or methyl;

M ¹ is hydrogen, monovalent metal, divalent metal, ammonium, or organic amine;

In Chemical Formula 2,

R ² is hydrogen or methyl;

R ³ is alkylene, phenylene or alkylphenylene having 2 or 3 carbon atoms;

R ⁴ is one kind or a mixture of two or more kinds of oxyalkylenes having 2 to 4 carbon atoms, and in the case of two or more kinds, R ⁴ may be added in a block or random phase;

m is an integer of 10 to 50 as the average added mole number of the oxyalkylene group;

n is 0 or 1;

M ² is a hydrogen atom, a monovalent metal atom, an ammonium or an organic amine group.

As the acrylic acid copolymer containing the reactive surfactant as a unit monomer, an acrylic acid-acrylamide-reactive surfactant copolymer is preferable, and in this case, the ratio of acrylic acid and acrylamide in the acrylic acid-acrylamide-reactive surfactant copolymer is weight ratio. 4 4: 9 to 9: 1.

In acrylic copolymer, when the content of acrylic acid in the copolymer is less than 40% by weight, it is impossible to expect a desirable water-resistance effect. When the content of the acrylic acid-based copolymer exceeds 90% by weight, the initial sensitivity is improved, but the slump loss is increased so that the holding power is significantly decreased. This can happen.

As the acrylic acid copolymer containing the reactive surfactant as a unit monomer, an acrylic acid-maleic anhydride-reactive surfactant copolymer may also be used.                     

The acrylic acid-based copolymer containing the reactive surfactant as a unit monomer serves to improve initial dispersibility as the reactive surfactant is introduced.

More specifically, the reactive surfactant introduced to the acrylic acid copolymer has both hydrophobic and hydrophilic groups to improve the solubility of the polymer, and increases the dispersibility and fluidity of the cement particles by increasing the properties that can cause physical adsorption to the cement particles. Play a role in improving

The polyalkylene glycol ester-based polycarboxylic acid fluidizing agent used in the blending of the cement admixtures has the electrostatic repulsive force of the polycarboxylic acid group, the repulsive force due to the steric hindrance effect of the polyalkylene glycol ester group, and the oxide and water in the chain. As well as the cement dispersion effect by the electric double layer effect due to hydrogen bonding, as well as the electrostatic repulsion by the sulfonic acid at the end of the reactive surfactant at the same time, the dispersion force and the stability of entrained air have more excellent characteristics.

The blending ratio of the acrylic acid copolymer containing the reactive surfactant as the unit monomer and the polyalkylene glycol ester polycarboxylic acid fluidizing agent is preferably 3: 7 to 7: 3 by weight.

When blending as described above to produce a cement admixture when the acrylic acid copolymer is less than 30% by weight can not be expected to increase the initial susceptibility by the electrostatic repulsion of the carboxylic acid group, when used in excess of 70% by weight The problem that the fluidity and slump retention of the cement composition exhibited by the steric hindrance effect of the alkylene glycol ester group may be significantly lowered.                     

The present invention provides a cement admixture, which is prepared by the above production method.

In addition, the present invention a) 100 parts by weight of cement; And b) 0.01 to 10 parts by weight of the cement admixture provides a cement composition comprising.

If the cement admixture is used in an amount less than 0.01 parts by weight, a desirable fluidity improvement effect cannot be expected, and when it is used in an amount exceeding 10 parts by weight, further improvement in fluidity is extremely insignificant. It is desirable to.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the examples.

(Example 1)

155 parts by weight of water and 450 parts by weight of isopropyl alcohol were introduced into a 2 L capacity glass reactor equipped with a thermometer, agitator, dropping funnel, nitrogen inlet tube and reflux cooler, and the reaction vessel was replaced with nitrogen by stirring at 83 ° C. under a nitrogen atmosphere. Heated to

Monomer aqueous solution of 209.5 parts by weight of acrylic acid, 222.85 parts by weight of acrylamide, 13.37 parts by weight of polyoxyethylene nonylphenyl propenyl ether sulfate ammonium salt (10 moles of ethylene oxide average added mole number) as a reactive surfactant, and 300 parts by weight of water. And 163.6 parts by weight of an aqueous solution of 14.4% by weight of ammonium persulfate as an initiator were added dropwise for 3 hours. After completion of the dropwise addition, the polymerization reaction was completed by maintaining the temperature at 83 ° C for 2 hours.

After the polymerization was completed, isopropyl alcohol and water were distilled for 2 to 3 hours while increasing the pressure from normal pressure to 10 torr slowly. It was then cooled to room temperature and neutralized with an aqueous 30% wt sodium hydroxide solution for about 30 minutes.

The salt of the acrylic acid copolymer prepared as described above was 4,277 when the weight average molecular weight was measured by Gel Permeation Chromatography (GPC).

 The cement admixture was prepared by blending the acrylic acid copolymer prepared above and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical Co., Ltd., CP-WB) at 5: 5.

(Example 2)

The cement admixture was prepared by blending the acrylic acid copolymer prepared in the same manner as in Example 1 and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical, trade name CP-WB) at 4: 6.

(Example 3)

A salt of an acrylic acid copolymer was prepared in the same manner as in Example 1, except that acrylic acid was used in an amount of 245.1 parts by weight and acrylamide was used in an amount of 187.2 parts by weight.

The salt of the acrylic acid copolymer prepared as described above was 3,487 when the weight average molecular weight was measured by Gel Permeation Chromatography (GPC) method.

The cement admixture was prepared by blending the acrylic acid copolymer prepared above and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical Co., Ltd., CP-WB) at 5: 5.

(Example 4)

The cement admixture was prepared by blending the acrylic acid copolymer prepared in the same manner as in Example 3 and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical Co., Ltd., CP-WB) at 4: 6.

(Example 5)

Acrylic acid copolymer was used in the same manner as in Example 1, except that 298.6 parts of acrylic acid and 133.7 parts by weight of acrylamide were used, and an ammonium persulfate aqueous solution of 16.6% by weight was used as an initiator. The salt of was prepared.

The salt of the acrylic acid copolymer prepared as described above was 3,115 when the weight average molecular weight was measured by Gel Permeation Chromatography (GPC).

The cement admixture was prepared by blending the acrylic acid copolymer prepared above and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical Co., Ltd., CP-WB) at 5: 5.                     

(Example 6)

The cement admixture was prepared by blending the acrylic acid copolymer prepared in the same manner as in Example 5 and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical Co., Ltd., CP-WB) at 4: 6.

(Example 7)

Acrylic acid copolymer was used in the same manner as in Example 1, except that 334.28 parts by weight of acrylic acid and 98.05 parts by weight of acrylamide were used, and an ammonium persulfate aqueous solution of 12.1% by weight was used as an initiator. The salt of was prepared.

The salt of the acrylic acid copolymer prepared as described above was 3,925 when the weight average molecular weight was measured by Gel Permeation Chromatography (GPC).

The cement admixture was prepared by blending the acrylic acid copolymer prepared above and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (manufactured by LG Chemical Co., Ltd., trade name CP-WB) at 5: 5.

(Example 8)

A cement admixture was prepared by blending the acrylic acid copolymer prepared in the same manner as in Example 7 and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical, trade name CP-WB) at 4: 6.

(Example 9)                     

378.85 parts by weight of acrylic acid, 53.48 parts by weight of acrylamide were used, and the same procedure as in Example 1 except that 5.4% by weight of ammonium persulfate aqueous solution was changed to 148 parts by weight of an initiator. Salts were prepared.

The salt of the acrylic acid copolymer prepared as described above was 5,570 when the weight average molecular weight was measured by Gel Permeation Chromatography (GPC).

The cement admixture was prepared by blending the acrylic acid copolymer prepared above and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical Co., Ltd., CP-WB) at 5: 5.

(Example 10)

The cement admixture was prepared by blending the acrylic acid copolymer prepared in the same manner as in Example 9 and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical Co., Ltd., CP-WB) at 4: 6.

(Example 11)

The cement admixture was prepared by blending the acrylic acid copolymer prepared in the same manner as in Example 1 with a polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical, trade name CP-WB) at 6: 4.

(Example 12)

A cement admixture was prepared by blending a polyacrylic acid copolymer prepared in the same manner as in Example 3 and a polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical, trade name CP-WB) at 6: 4.

(Example 13)

The cement admixture was prepared by blending the polyacrylic acid copolymer prepared in the same manner as in Example 5 and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical, trade name CP-WB) at 6: 4.

(Example 14)

A cement admixture was prepared by blending a polyacrylic acid copolymer prepared in the same manner as in Example 7 and a polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical, trade name CP-WB) at 6: 4.

(Example 15)

The cement admixture was prepared by blending the polyacrylic acid copolymer prepared in the same manner as in Example 9 and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical, trade name CP-WB) at 6: 4.

(Comparative Example 1)

Naphthalenesulfonic acid formaldehyde condensate (NSF), which is applied as a conventional cement admixture, was used as the cement admixture.

(Comparative Example 2)

Lignin-based and naphthalene sulfonic acid formaldehyde condensate (NSF), which is applied as a conventional cement admixture, was mixed at a ratio of 1: 1 and used as a cement admixture.                     

The content and properties of each component of the acrylic acid copolymer (acrylic acid-acrylamide-reactive surfactant copolymer) prepared in the above examples are shown in Table 1 below.

TABLE 1

division Acrylic acid Acrylamide Reactive surfactant Solid content of the preparation (% by weight) Weight average molecular weight Polydispersity index (PDI) Copolymer Content (wt%) Copolymer Content (wt%) Copolymer Content (wt%) Example 1 47 50 3 40.2 4,277 1.57 Example 3 55 42 3 40.0 3,487 1.75 Example 5 67 30 3 40.1 3,115 1.7 Example 7 75 22 3 40.1 3,925 1.95 Example 9 85 12 3 40.3 5,570 2.06

(Test example)

Mortar Fluidity Test

Medium Portland Cement (Ssangyong Cement) 665 g, sand (standard sand) 1,350 g, 1.33 g (in terms of solids) and 332.5 g of cement admixture prepared in each of Examples and Comparative Examples, medium speed 3 minutes in a mortar mixer The mixture was kneaded to prepare mortar.

Each prepared mortar was filled with a hollow cone having a diameter of 60 mm and a height of 40 mm, and then the cone was removed in a vertical direction. Mortar flow value (mm) measured the mortar diameter in two directions, and made it the average of the measured diameters.

[Concrete test]

Cement admixtures prepared in Portland cement (Ssangyong Shoe) 3.53 kg, sand 7.94 kg, crushed stone 10.01 kg, Examples and Comparative Examples, respectively, were kneaded with 1.0% by weight of cement weight and 1.66 kg of water (water supply). Prepared.

Each concrete manufactured was measured for slump and air volume according to Korean Industrial Standards KS F 2402 and KS F 2449.

The cement admixture prepared by blending the acrylic acid copolymer prepared in the above example and the polyalkylene glycol ester-based polycarboxylic acid fluidizing agent (LG Chemical Co., Ltd., CP-WB) in respective proportions and the cement admixture prepared in Comparative Example Mortar fluidity test and test applied to concrete (concrete test) results are shown in Table 2 below.

TABLE 2

division Addition amount (wt%) relative to 100 wt% cement Mortar Flow Value (mm) Concrete slump (cm) Concrete air volume (%) Mortar admixture Concrete admixture Early 30 minutes later Early 30 minutes later Early 30 minutes later Example 1 0.7 1.0 142 130 20.5 14.0 2.2 2.1 Example 2 0.7 1.0 145 132 21.0 14.5 2.9 2.8 Example 3 0.7 1.0 147 140 21.0 15.0 3.4 3.2 Example 4 0.7 1.0 145 138 21.5 15.0 3.3 3.3 Example 5 0.7 1.0 152 142 23.0 17.5 3.0 2.9 Example 6 0.7 1.0 149 139 23.0 17.5 3.2 3.1 Example 7 0.7 1.0 150 135 21.5 15.5 3.6 3.2 Example 8 0.7 1.0 151 138 22.0 15.5 3.8 3.5 Example 9 0.7 1.0 147 129 20.0 13.0 3.6 3.3 Example 10 0.7 1.0 146 131 20.5 14.0 3.7 3.4 Example 11 0.7 1.0 141 126 18.0 12.0 3.4 3.0 Example 12 0.7 1.0 143 130 19.5 12.5 3.7 3.3 Example 13 0.7 1.0 144 133 20.0 13.5 2.9 2.9 Example 14 0.7 1.0 146 131 20.0 13.0 3.2 3.0 Example 15 0.7 1.0 140 125 19.5 12.5 3.6 3.1 Comparative Example 1 0.7 1.0 136 116 17.0 11.0 3.5 3.3 Comparative Example 2 0.7 1.0 151 140 21.0 14.0 3.8 3.5

Looking at the test results, the mortar to which the cement admixture of the present invention is applied in Example is relatively relative to the mortar of Comparative Example 1 (naphthalene system) and Comparative Example 2 (lignin-naphthalene system) to which the cement admixture of the present invention is not applied. The high fluidity was maintained and the concrete slump value was not only excellent but also the slump retention after 30 minutes was relatively high. In addition, the amount of air was also lower than that of the conventional polycarboxylic acid-based fluidizing agent.

This is because the cement admixture of the present invention improves the dispersibility of the cement particles to increase the flowability of the composition in the region of high susceptibility even with a small amount of addition, and to give a good workability to the cement composition can form a concrete having high strength Is showing.

The cement admixture prepared by the method of preparing the cement admixture of the present invention can improve the dispersibility of cement particles than the conventional cement admixture, and improve the initial susceptibility by the excellent initial dispersibility, while the fluidity of the cement composition even in the region of high susceptibility. It is possible to increase the flow rate, prevent the decrease in the obtained fluidity over time, and maintain high fluidity.

In addition, when the cement admixture of the present invention is used, the concrete slump value is excellent, the slump holding force is high, and the air amount is lower than that of the conventional polycarboxylic acid-based fluidizing agent, and it is possible to give excellent working stability than the conventional cement admixture.

Claims (8)

A method for producing a cement admixture, characterized by blending an acrylic acid copolymer containing a reactive surfactant as a unit monomer and a polyalkylene glycol ester polycarboxylic acid fluidizing agent. The acrylic acid copolymer according to claim 1, wherein the acrylic acid copolymer containing a reactive surfactant as a unit monomer a) 45 to 90% by weight of a (meth) acrylic acid monomer or salt thereof represented by Formula 1; And b) a method of producing a cement admixture, comprising 0.5 to 40 wt% of a reactive surfactant represented by the following Chemical Formula 2: [Formula 1]

[Formula 2]

In Chemical Formula 1, R ¹ is hydrogen or methyl; M ¹ is hydrogen, monovalent metal, divalent metal, ammonium, or organic amine; In Chemical Formula 2, R ² is hydrogen or methyl; R ³ is alkylene, phenylene or alkylphenylene having 2 or 3 carbon atoms; R ⁴ is one kind or a mixture of two or more kinds of oxyalkylenes having 2 to 4 carbon atoms, and in the case of two or more kinds, R ⁴ may be added in a block or random phase; m is an integer of 10 to 50 as the average added mole number of the oxyalkylene group; n is 0 or 1; M ² is a hydrogen atom, a monovalent metal atom, an ammonium or an organic amine group. The method of claim 1, wherein the acrylic acid copolymer is an acrylic acid-acrylamide-reactive surfactant copolymer. 4. The process for producing a cement admixture according to claim 3, wherein the ratio of acrylic acid and acrylamide in the acrylic acid-acrylamide-reactive surfactant copolymer is 4: 6 to 9: 1 by weight. The method of claim 1, wherein the acrylic acid copolymer is an acrylic acid-maleic anhydride-reactive surfactant copolymer. The method for producing a cement admixture according to claim 1, wherein the blending ratio of the acrylic acid copolymer and the polyalkylene glycol ester polycarboxylic acid fluidizing agent is 3: 7 to 7: 3 by weight. A cement admixture, which is prepared by the process according to any one of claims 1 to 6. a) 100 parts by weight of cement; And b) 0.01 to 10 parts by weight of the cement admixture according to claim 7 Cement composition comprising a.