JPH0662326B2 - Admixture for cement - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel admixture for hydraulic cement, more specifically, a novel polyadmixture having excellent properties as a dispersant, a water reducing agent, a fluidizing agent, etc. The present invention relates to a carboxylic acid-based admixture for hydraulic cement.

(Prior Art) Generally, concrete using cement, mortar,
When manufacturing a paste or the like, an admixture called a dispersant, a water reducing agent or a fluidizing agent is used. This admixture is expected to have the following main effects. That is, (1) increase the workability of the cement composition that has not yet set. If the workability is the same, the amount of water used will be reduced. (2) Since the amount of water used can be reduced, the strength after construction is increased as a result. If the strength is the same, the amount of cement used will be reduced. (3) Increasing water tightness.

Conventionally, such admixtures include lignin sulfonic acid type, oxycarboxylic acid type, β-naphthalene sulfonic acid type,
Formalin condensate system, melamine sulfonic acid / formalin condensate system, olefin-α, β-unsaturated dicarboxylic acid copolymer system (hereinafter sometimes simply referred to as polycarboxylic acid system), etc. are known. Polycarboxylic acid-based admixtures have recently been actively researched as showing good dispersion fluidity even with a small addition amount and excellent slump retention (for example, Japanese Patent Publication No. 53-18215). 53-38095 and JP-A-58-213663).

However, such a polycarboxylic acid-based admixture is not necessarily one that can sufficiently satisfy the required performance for the more advanced dispersion fluidity and slump retention, and since these are generally used in the form of a sodium salt, they are alkaline. It has been feared that the aggregate reaction may lower the performance.

Further, recently, a method of using a complex salt of an alkali metal and an alkaline earth metal as a water-soluble salt of a copolymer of a lower olefin having 2 to 4 carbon atoms and maleic anhydride (JP-A-60-103062). ) Was developed, but in this case as well, there is a concern that the alkali-aggregate reaction remains as the main component, and the compressive strength is not sufficiently improved.

(Problems to be Solved by the Invention) Therefore, as a result of intensive studies conducted by the present inventors to overcome such drawbacks of the prior art, when a porcarboxylic acid complex salt having a specific composition containing no alkali metal is used, an alkali bone It is possible to eliminate the concern of material reaction, moreover, the dispersion fluidity of the cement is better than the conventionally known polycarboxylic acid-based admixtures, and a cement mixture with good workability with significantly suppressed slump deterioration can be obtained and has high strength. The inventors have found that a cured product of the above can be obtained, and have completed the present invention.

(Means for Solving the Problems) Thus, according to the present invention, a water-soluble cement admixture containing a water-soluble salt of a copolymer of α, β-unsaturated dicarboxylic acid and olefin as an active ingredient There is provided an admixture for hydraulic cement, wherein the salt is a composite salt of an alkaline earth metal salt and an amine salt, and the equivalent ratio of the alkaline earth metal salt to the amine salt is 0.05 to 1.

The copolymer used in the present invention is composed of α, β-unsaturated dicarboxylic acid and olefin. The composition of such a copolymer can be appropriately selected, but usually (a) α, β
-Unsaturated dicarboxylic acid 40-85 mol%, preferably 6
5 to 80 mol% and (b) olefin 60 to 15 mol%, preferably 35 to 20 mol%. The number average molecular weight is usually 300 to 10,000, preferably 1,000.
It is particularly suitable that the high molecular weight portion having a molecular weight of 20,000 or more is controlled to 10% by weight or less, and further 8% by weight or less of the whole.

Here, the number average molecular weight means that measured by a high-performance liquid chromatograph (tetrahydrofuran solvent, measurement temperature 40 ° C.) in terms of polystyrene.

In particular, a sharper molecular weight distribution tends to show better performance, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2.0 or less, and more preferably 1.9 or less. .

Specific examples of the component (a) that constitutes the copolymer include maleic acid, itaconic acid, citraconic acid, and their anhydrides, with maleic anhydride being industrially advantageous.

On the other hand, specific examples of the component (b) include ethylene, propylene, isobutylene, butene-1, butene-2, pentene-1, pentene-2, 2-methylbutene-1,2-.
Chain olefins such as methylbutene-2, 4-methylpentene-1, hexene-1, etc., cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclopentadiene, dicyclopentadiene, 2-ethyl-5-norbornene, 2-cyano. -5
Examples include cycloolefin such as norbornene and 2-acetyl-5-norbornene, and among them C
_4-6 chain _olefins, cycloolefin of _{C 4-6} is Shoyo.

Further, within the range that does not substantially impair the effects of the present invention,
A vinyl monomer such as acrylic acid, vinyl acetate, methyl methacrylate, methyl vinyl ether, acrylonitrile, or ethylene sulfonic acid may be copolymerized, and a part of the carboxyl group and / or acid anhydride group in the copolymer may be copolymerized. It can also be used after being esterified or amidated.

The method for producing the copolymer used in the present invention is not particularly limited, and can be easily obtained by radical polymerization according to a conventional method. Further, in order to obtain a copolymer having a large amount of α, β-unsaturated dicarboxylic acid units, an excess amount of α, β-unsaturated dicarboxylic acid may be charged with respect to olefin and radical polymerization may be performed, and the amount of the high molecular weight portion may be small. In order to obtain the copolymer, the high molecular weight portion may be removed by ultrafiltration, or the high molecular weight portion may be extracted and separated using a solvent.

In the present invention, a part or all of the carboxyl group and / or acid anhydride group present in the copolymer is used as a salt to enhance the water-solubilizing ability, and in that case, the alkaline earth metal salt to the amine salt is used. Equivalent ratio of 0.05 to 1, preferably
It is necessary to use 0.1 to 0.8 equivalents.

When the ratio of the alkaline earth metal salt is too small, the effect of improving dispersion fluidity, slump retention and strength is not sufficient,
On the contrary, if the ratio is too large, the water-solubilizing ability becomes insufficient.

The alkaline earth metal used in the present invention is calcium, magnesium, barium, or the like, and among them, calcium has the prize.

Specific examples of amines that serve as amine salts include methylamine, ethylamine, propylamine, isopropylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, trimethylamine, triethylamine, tripropylamine, monoethanolamine, diethanolamine, triethanol. Examples thereof include amines, and among them, tertiary amines, especially triethanolamine, are also favored.

The use form of the admixture of the present invention is not particularly limited, and it can be used in the form of an aqueous solution or a solid form such as powder, and can be used alone or in combination with other cement admixtures. Examples of the cement admixture that can be used in combination include conventional cement dispersants, air entraining agents, cement wetting dispersants, swelling agents, waterproofing agents, strength enhancers, hardening accelerators, setting accelerators,
Examples include setting retarders and the like.

The amount of the cement admixture of the present invention may be appropriately selected according to the required performance, on the basis of solid content for cement,
Usually, it is used in a proportion of 0.01 to 3% by weight, preferably 0.05 to 1% by weight. The workability improving effect decreases as the amount of use decreases, and conversely, when the amount is excessively large, the hardening of the cement may be adversely affected.

Further, the timing of addition to the cement mixture can be appropriately selected according to the purpose of use. As a specific method thereof, for example, a method of premixing with cement, a method of simultaneously adding the cement mixture such as concrete at the time of kneading, a method of adding water or another admixture after starting stirring, and preliminarily mixing An example of such a method is to knead the product and then add it at an appropriate interval. Above all, a remarkable effect is exhibited when used by a method of simultaneously adding at the time of kneading.

The type of cement to which the hydraulic cement admixture of the present invention can be applied is not particularly limited, and specific examples thereof include ordinary Portland cement, early strength Portland cement,
Moderate heat Portland cement, Alumina cement, Fly Ash cement, Blast furnace cement, Silica cement,
Examples include slag cement and various mixed cements.

(Effects of the Invention) Thus, according to the present invention, an admixture for cement that does not cause an alkali-aggregate reaction is provided, and by using the admixture for cement, the dispersion fluidity of the cement is good and the workability that significantly suppresses the slump decrease is provided. It is possible to obtain a cement mixture with good quality and to obtain a cured product with high strength.

(Example) Hereinafter, the present invention will be described more specifically with reference to Examples. The parts and% in the examples and reference examples are based on weight unless otherwise specified.

Reference Example 1 In an autoclave under a nitrogen atmosphere, 98 parts of maleic anhydride, 76 parts of a C ₅ olefin mixture shown in Table 1,
A mixture of 4 parts of benzoyl peroxide and 400 parts of benzene was heated and stirred at 70 to 75 ° C. for 8 hours to be reacted. After the completion of the polymerization reaction, the precipitated copolymer was separately collected and dried to obtain a C ₅ olefin-maleic anhydride copolymer.

Next, this copolymer was dissolved in methyl ethyl ketone, and it was passed through a membrane having a separation limit molecular weight of 20,000 to remove a high molecular weight portion.

The composition, the number average molecular weight, the weight average molecular weight, and the content of the high molecular weight portion having a molecular weight of 20,000 or more were measured for the copolymer thus obtained.

Further, 300 parts of water was added to 100 parts of this copolymer, 5.5 parts of calcium hydroxide was gradually added with stirring and dissolved, and then 198 parts of triethanolamine was gradually added and stirred to obtain a copolymer. An aqueous solution of salt (I) was obtained. The results are shown in Table 2.

Table 1 iso-pentane about 16% n-pentane about 15% 2-methylbutene-1 about 42% pentene-1 about 27% isobrene 0.1% or less Reference Example 2 24.6 parts of calcium hydroxide and triethanolamine 121
A copolymer salt (II) aqueous solution was obtained by the same operation as in Reference Example 1 except that parts were used. The properties are shown in Table 2.

Reference Example 3 6.2 parts of magnesium carbonate and triethanolamine 198
An aqueous solution of copolymer salt (III) was obtained by the same procedure as in Reference Example 1 except that parts were used. The properties are shown in Table 2.

Reference Example 4 Triethanolamine 22 without using calcium hydroxide
An aqueous solution of copolymer salt (IV) was obtained in the same manner as in Reference Example 1, except that 0 part was used. The properties are shown in Table 2.

Reference Example 5 An aqueous solution of copolymer salt (V) was obtained in the same manner as in Reference Example 1, except that only 59 parts of sodium hydroxide was used. The properties are shown in Table 2.

Reference Example 6 A copolymer salt was prepared in the same manner as in Reference Example 1 except that 24.6 parts of calcium hydroxide and 32.4 parts of sodium hydroxide were used.
An aqueous solution of (VI) was obtained. The properties are shown in Table 2.

Example 1 The performance of various copolymer salts obtained in Reference Example as a hydraulic cement admixture was evaluated according to the following mortar test conditions. The results are shown in Table 3.

[Mortar test]

Adjust the cement mortar with the following composition, JIS-R-5201
The mortar test was carried out according to
The amount of admixture added was adjusted to be mm. The air entrainment amount was measured according to JIS-A-1116. The mortar temperature was 20 ° C ± 2 ° C, and the temperature in water curing for measuring the compressive strength was 20 ° C ± 2 ° C.

It can be seen from Table 3 that the inventive examples can provide a cured product having high work strength and high strength over a long period of time with a small amount of addition as compared with the comparative examples.

Example 2 Among the samples subjected to the mortar test in Example 1, the copolymer salts (I), (III), (IV), (V) and (VI) had high strength according to the following concrete test conditions. An evaluation was made with a concrete mix. The results are shown in Table 4.

[Concrete test]

Cement, water, aggregate and hydraulic cement admixture were blended according to the following formulation, then kneaded with a forced kneading mixer for 90 seconds, then slump and air amount were measured, and then 30 minutes later.
After 60 minutes, they were kneaded again, and the slump and the air amount were measured. After 60 minutes, a sample for compressive strength measurement was taken. Immediately after kneading, the slump target is slump 20 ± 1
The amount of admixture added was adjusted to be cm. The measurement method is
The slump was in accordance with JIS A1101, the air volume was in accordance with JIS A1116, and the compressive strength was in accordance with JIS A1108. The concrete temperature was 20 ° C. ± 2 ° C., and the compressive strength measurement sample was aged in water at 20 ± 2 ° C.

Concrete-mixed cement: 450kg / m ² Asano ordinary Portland cement Coarse aggregate: 1006〃 Ome crushed stone (maximum particle size 25mm) Fine aggregate: 747〃 Oigawa river sand water: 162〃 (total amount with admixture) Hydraulic cement Admixture: As shown in Table 4, water / cement ratio = 36% Fine aggregate ratio = 43% Example 3 Copolymer salts (I), (III), (IV), (V) and (V used in Example 2
Regarding I), the following concrete composition was evaluated for general concrete composition. The results are shown in Table 5.

Concrete mixed cement: 300kg / m ² Asano ordinary Portland cement Coarse aggregate: 1012〃 Ome crushed stone (maximum particle size 25mm) Fine aggregate: 815〃 Oigawa river sand water: 166.0〃 (total amount with admixture) Hydraulic cement Admixture: As shown in Table 5 Water / cement ratio: 55.3% Fine aggregate ratio: 44.6% Target slump: 10 ± 1 cm Target air volume: 4.5 ± 0.5% (Air volume adjustment vinsol: Yamasou Chemical Co., Ltd.) From Table 5, it can be seen that even in the case of general-purpose concrete blending, the examples of the present invention show good performance with a low addition amount as compared with the comparative examples.

Claims (1)

[Claims] 1. A hydraulic cement admixture containing a water-soluble salt of a copolymer of α, β-unsaturated dicarboxylic acid and olefin as an active ingredient, wherein the water-soluble salt is a complex of an alkaline earth metal salt and an amine salt. An admixture for hydraulic cement, which is a salt and has an equivalent ratio of an alkaline earth metal salt to an amine salt of 0.05 to 1.