JPH0859323A - Dispersant for concrete - Google Patents

Abstract

PURPOSE: To obtain a dispersant for concrete capable of keeping the fluidity of concrete for a long time and improved in the strength of concrete by mixing a specific copolymer with an organic or inorganic electrolyte. CONSTITUTION: This dispersant for concrete consists of the copolymer, which is composed of 10-90wt.% unsaturated carboxylic acid based monomer (a) and 90-10wt.% unsaturated polyalkylene glycol carboxylate monomer (b), and/or a copolymer obtained by neutralizing the copolymer and containing the organic and/or inorganic electrolyte in the ratio of 99:1-(50:50). The dispersant is used in the weight ratio of 0.01-1%, preferably 0.05-0.6%, to cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete composition, and more particularly to a dispersant for concrete which reduces the change in fluidity of fresh concrete over time and improves the compressive strength of concrete.

[0002]

2. Description of the Related Art There has been a strong demand for improvement in workability of fresh concrete and improvement in strength and durability of hardened concrete, and in recent years, in order to achieve this requirement, high flowability or high strength concrete has been required. It is becoming popular. A polycarboxylic acid-based high-performance AE water reducing agent is generally used when producing this high-fluidity and high-strength concrete.

[0003]

The fluidity at the time of kneading concrete is required until pouring. Due to its steric hindrance, polycarboxylic acid-based high-performance AE water reducing agents have a particularly low water cement ratio (hereinafter, the water cement ratio is described as W / C).
When it is, that is, when the addition amount is large, the fluidity retaining effect is exhibited, but in high and medium W / C concrete, the addition amount is small, so that the fluidity changes with time. If the change in fluidity with time is large, the workability at the time of placing will be reduced. Even in high and medium W / C concrete, if the addition amount is increased, the steric hindrance effect exerts a fluidity retaining effect, but since the initial fluidity becomes excessively large, material separation occurs and the concrete strength decreases. Invite.

On the other hand, the strength of concrete is almost determined by W / C, and it is necessary to reduce W / C in order to obtain high strength. However, if the unit amount of water is made small in order to reduce W / C, the viscosity of concrete remarkably increases and the workability deteriorates. Further, even if the amount of cement is increased, not only the viscosity of concrete remarkably increases and the workability decreases but also the cost increases, which is not economical. Therefore, there is a strong demand for a dispersant for concrete which can maintain fluidity in a wide W / C range and can provide concrete strength without lowering W / C.

[0005]

In view of the above background, the present invention provides a dispersant for concrete capable of maintaining the fluidity of concrete for a long time and improving the strength of concrete.

The present inventors have found that polycarboxylic acid type high performance A
E When a water reducing agent is mixed with an auxiliary component, the dispersibility decreases and the required addition amount increases, but on the other hand, the fluidity retention performance of concrete is greatly improved and at the same time the strength of concrete is significantly improved. Found and arrived at the present invention.

The present invention comprises (1) a copolymer composed of 10 to 90% by weight of an unsaturated carboxylic acid type monomer (a) and 90 to 10% by weight of an unsaturated polyalkylene glycol carboxylic acid ester type monomer (b). The polymer and / or the copolymer obtained by further neutralizing the copolymer and the organic and / or inorganic electrolyte have a mixing ratio of 99: 1 to 5
(2) 10 to 90% by weight of unsaturated carboxylic acid type monomer (a) and 90 to 10% by weight of unsaturated polyalkylene glycol carboxylic acid ester type monomer (b). And 1 to 50% by weight of a monomer (c) copolymerizable with these monomers (here, the total of (a), (b) and (c) is 100% by weight). Dispersant for concrete, wherein the polymer and / or the copolymer obtained by further neutralizing the copolymer and the organic and / or inorganic electrolyte have a mixing ratio of 99: 1 to 50:50, (3) organic and And / or the dispersant for concrete according to the above (1) or (2), wherein the inorganic electrolyte is an admixture for concrete.

Unsaturated carboxylic acid type monomer (a) of the present invention
Are, for example, acrylic acid, methacrylic acid, maleic acid and fumaric acid, and acrylic acid and methacrylic acid are particularly preferable from the viewpoint of ease of production of the copolymer. Further, these monovalent metal salts, polyvalent metal salts, ammonium salts and organic amine salts may be used, particularly preferably Na salts and Ca salts, and one or more of these may be used.

The unsaturated polyalkylene glycol carboxylic acid ester monomer (b) is, for example, polyethylene glycol monomethacrylate, polyethylene glycol monoacrylate, polypropylene glycol monomethacrylate, polypropylene glycol monoacrylate, methoxypolyethylene glycol monomethacrylate, methoxypolyethylene glycol. Mention may be made of monoacrylate, methoxy polypropylene glycol monomethacrylate, methoxy polypropylene glycol monoacrylate, ethoxy polyethylene glycol monomethacrylate, ethoxy polyethylene glycol monoacrylate, ethoxy polypropylene glycol monomethacrylate, ethoxy polypropylene glycol monoacrylate. , It can be used alone or in combination of two or more thereof.

Here, the number of moles of ethylene oxide or propylene oxide or a mixed chain thereof added per monomer is 1 to 100, preferably 2 to 80. Outside of this range, there are drawbacks such that the steric hindrance effect becomes small and the fluidity retention effect becomes insufficient, and the viscosity of the copolymer is high and the workability is deteriorated.

The monomer (c) copolymerizable with the monomers (a) and (b) is, for example, an aromatic vinyl such as styrene and styrene sulfonic acid, an allyl sulfonic acid, a methallyl sulfonic acid and the like. Examples thereof include saturated sulfonic acids, unsaturated esters such as ethyl methacrylate, unsaturated amides of acrylamide, and the like, and one or more of these can be used.

The ratio of the monomers (a) and (b) is preferably 10 to 90% by weight of the monomer (a) and 90 to 10% by weight of the monomer (b). If the amount of the monomer (a) is less than 10% by weight, the dispersibility will not be exhibited, and if the amount of the monomer (b) is less than 10% by weight, the steric hindrance action will be small and the fluidity retaining effect will be insufficient.

When the monomer (c) is used, (a) 10
˜90 wt%, 90 to 10 wt% monomer (b) and 1 to 50 wt% (c). Where (a),
The total of (b) and (c) is 100% by weight. Even if the amount of the monomer (c) exceeds 1 to 50% by weight, the steric hindrance action becomes small and the fluidity retaining effect becomes insufficient.

To produce the copolymer, the above-mentioned monomer components may be copolymerized in a solvent of water or a lower alcohol using a polymerization initiator. The copolymer is preferably a monovalent metal salt such as K or Na, but is a polyvalent metal salt such as Ca or Mg, or NH.
It may be an organic amine salt such as a 4-salt or triethanolamine.
Further, the molecular weight of the copolymer is preferably 500 to 500,000, and if it is less than 500, the steric hindrance effect becomes small and the fluidity retaining effect becomes insufficient, and if it exceeds 500,000, the viscosity becomes high. It is not economical because the concentration must be low. It may also serve as an aggregating agent.

The organic and / or inorganic electrolyte of the present invention is an admixture for concrete, for example, water reducing agent, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent, shrinkage reducing agent, setting accelerator, setting retarder, It is desirable to use one that is used as an inseparable admixture in water, etc., as long as it does not adversely affect the physical properties of concrete.
More than one species can be used. These are not added only to support the inherent performance of each, but they lower the dispersibility of the polycarboxylic acid salt and the effect of maintaining the fluidity by increasing the addition amount of the polycarboxylic acid salt. And the compressive strength of concrete.

Examples of the water reducing agent, AE water reducing agent, and high-performance AE water reducing agent include, for example, those containing lignin sulfonate or its derivative as a main component, those containing oxyorganic acid salt such as sodium gluconate as a main component, and naphthalene. Examples thereof include sulfonic acid formaldehyde condensate, melamine sulfonic acid formaldehyde condensate, phenol / sulfanilic acid formaldehyde condensate, bisphenols / sulfanilic acid formaldehyde condensate, C4 or C5 fraction-maleic anhydride copolymer, and the like.

Further, examples of the shrinkage reducing agent include those containing a lower alcohol alkylene oxide adduct and an ether type nonionic surfactant as a main component.

Examples of the setting accelerator and the setting retarder include sodium aluminate, sodium carbonate, sodium silicate, calcium aluminate, calcium sulfaluminate, glycerin, triethanolamine and triisopropanolamine, and other organic amines, chlorides. In addition to chlorine compounds such as calcium, nitrates, nitrites, thiosulfates, thiocyanates, cellulose derivatives, water-soluble polymers such as polyvinyl alcohol, dextrin, sodium polyacrylate, and hydroxyl groups such as citric acid and 2-ketoglutaric acid. , Organic acids having a carboxyl group and a carbonyl group, sugars such as glucose and sorbitol, silicofluorides, and phosphates.

Examples of the non-separable admixture in water include cellulose-based polymers such as hydroxypropylmethyl cellulose and acrylic polymers such as partially hydrolyzed products of polyacrylamide. Acrylic-based and cellulose-based inseparable admixtures in water increase the viscosity of concrete, so it is necessary to be careful to use an addition rate that does not reduce workability. It is effective in some cases.

Further, the mixing ratio of the copolymer and the organic and / or inorganic electrolyte is 99: 1 to 50:50. If the amount of the organic and / or inorganic electrolyte is less than 1 part, the polycarboxylic acid cannot be added in a large amount, the steric hindrance effect is reduced, and the fluidity retention effect becomes insufficient. Further, when it exceeds 50 parts, the dispersion performance is remarkably deteriorated and the addition amount is greatly increased, which is not economical.

The dispersant for concrete of the present invention is 0.01 to 1% by weight with respect to cement, preferably 0.05.
~ 0.6% used. As the cement, ordinary Portland cement, early-strength Portland cement, moderate heat Portland cement, sulfate resistant Portland cement, blast furnace cement, fly ash cement, silica cement, and low heat-generating cement are used. Further, these can be used together with admixture materials such as silica fume and stone powder. In addition, the composition of concrete is not limited to a highly fluid one, and it can be used as a water reducing agent, an AE water reducing agent, a high performance water reducing agent, and a high performance AE water reducing agent with a general mixture of 5 to 21 cm slump.

Although the mechanism for increasing the strength is unknown, the amount of the strength increase is of course substantially W.
/ C is decreased (the admixture is regarded as a part of the unit amount of water, and therefore the unit amount of water is slightly reduced as the amount added is increased).

[0023]

The present invention will be described with reference to the following examples. All parts below mean parts by weight.

(Copolymer 1) 250 parts of isopropyl alcohol were placed in a separable flask equipped with a thermometer, a stirrer, a dropping funnel, a gas introduction tube and a condenser.
The inside of the flask was replaced with nitrogen while stirring. Next, under reflux, a dispersion liquid consisting of 80 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 9), 20 parts of methacrylic acid, 2.2 parts of benzoyl peroxide and 150 parts of isopropyl alcohol was added in 120 minutes. After completion of the addition, the polymerization reaction was completed by holding for another 120 minutes. Then, it was neutralized with a sodium hydroxide solution and isopropyl alcohol was distilled off to obtain an aqueous solution of copolymer 1.

(Copolymer 2, 3, 4)
Copolymers 2, 3, and 4 having the monomer composition ratios shown in Table 1 were produced.

[0026]

[Table 1]

The products of the present invention were prepared as shown in Table 2.

[0028]

[Table 2]

The materials used and the composition of concrete are as follows.

[0030]

[Table 3]

[0031]

[Table 4]

[0032]

[Table 5]

Table 3 (high W /
C), Table 4 (medium W / C), and Table 5 (low W / C), kneading amount of 80 liters of material and each dispersant were added, and kneading for 3 minutes, target slump 24 cm, target slump Concrete with a flow of 60 cm and a target air amount of 4.5% was obtained. After that, the slump flow was measured after 30, 60, and 120 minutes. The slump is JIS A 11
01, slump flow is based on the Japan Society of Civil Engineers “Slump flow test method for concrete (draft)”, air volume is JIS A
It measured based on 1128. Furthermore, the viscosity of concrete was evaluated by the flow time. This flow time is the time from when the slump cone was pulled up to when the slump flow reached 50 cm when measuring the slump flow, and the smaller the value, the lower the viscosity. The compressive strength was measured according to JIS A 1108.

The results are shown in Table 6 (high W / C) and Table 7 (medium W / C).
C) and Table 8 (low W / C). Comparative Examples 1 and 2 in the table,
3 is an example of using the copolymer 1, 2 is an example of increasing the addition rate, and 3 is an example of decreasing W / C. Only in Table 8, Comparative Example 3 with W / C of 28.5% is described.

In Comparative Example 1, the change in fluidity with time is large, and in Comparative Example 2, the compressive strength is lowered due to the material separation. Comparative Example 3 in Table 8 is an example in which W / C is lowered to increase the compressive strength, but the viscosity increases and the workability is insufficient. On the other hand, the product of the present invention shows a small change in fluidity with time, and shows that the compressive strength is increased with almost no increase in viscosity.

[0036]

[Table 6]

[0037]

[Table 7]

[0038]

[Table 8]

[0039]

EFFECTS OF THE INVENTION By using the product of the present invention, a concrete composition which can maintain the fluidity of concrete for a longer period of time than the conventional dispersants for concrete and which improves the strength of concrete can be produced.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C04B 24/18 B 24/22 E 24/30 D // C04B 103: 40 (72) Inventor Nagata Koji Higashimatsuyama City, Saitama Prefecture 1551 Todaira Inside Nippon Paper Industries Co., Ltd., Concrete Research Laboratory

Claims (3)

[Claims] 1. An unsaturated carboxylic acid-based monomer (a) 10-
90% by weight, a copolymer consisting of 90 to 10% by weight of an unsaturated polyalkylene glycol carboxylic acid ester-based monomer (b) and / or a copolymer obtained by further neutralizing the copolymer, Mixing ratio of organic and / or inorganic electrolyte 99:
Dispersant for concrete consisting of 1 to 50:50. 2. An unsaturated carboxylic acid-based monomer (a) 10 to
90% by weight, 90 to 10% by weight of unsaturated polyalkylene glycol carboxylic acid ester-based monomer (b), and 1 to 50% by weight of monomer (c) copolymerizable with these monomers.
(Here, the total of (a), (b), and (c) is 100% by weight) and / or a copolymer obtained by further neutralizing the copolymer and an organic compound. And / or a dispersant for concrete in which the inorganic electrolyte has a mixing ratio of 99: 1 to 50:50. 3. The dispersant for concrete according to claim 1, wherein the organic and / or inorganic electrolyte is an admixture material for concrete.