JPH0662327B2 - 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, may be simply referred to as polycarboxylic acid system), etc. are known. Polycarboxylic acid-based admixtures have recently been vigorously studied as those exhibiting good dispersibility and fluidity even when added in a small amount and having excellent slump retention (for example, Japanese Patent Publication No. 53-18215).
No. 53-38095, JP-A-58-213663.
No.).

However, such polycarboxylic acid-based admixtures are not always able to sufficiently satisfy the required performances for dispersion fluidity, slump retention and compressive strength, which have become more sophisticated with the recent diversification of cement and aggregate. It was

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 also in this case, there was a problem that the dispersion fluidity, slump retention and compression strength were 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 polycarboxylic acid complex salt having a specific composition is used, conventionally known polycarboxylic acid is used. It has been found that the dispersion fluidity of cement is better than that of an acid-based admixture, a cement composition with good workability in which slump deterioration is significantly suppressed can be obtained, and a cured product with high strength can be obtained, and the present invention has been completed. Came to do.

(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 an α, β-unsaturated dicarboxylic acid and an olefin as an active ingredient is water-soluble. The salt is (a) 5 to 90 equivalent% of the alkali metal salt, and (b) 5 to 5 of the alkaline earth metal salt.
There is provided an admixture for hydraulic cement, which is a complex salt consisting of 50 equivalent% and (c) 1 to 90 equivalent% of an amine salt.

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
It is composed of 5 to 80 mol% and (b) an olefin of 60 to 15 mol%, preferably 35 to 20 mol%. The number average molecular weight is usually 300 to 10,000, preferably 1,
It is particularly suitable that the high molecular weight portion having a molecular weight of 2,000 to 8,000 and a molecular weight of 20,000 or more is controlled to 10% by weight or less, and further 8% by weight or less.

Here, the number average molecular weight means a polystyrene equivalent value measured by a high performance liquid chromatograph (tetrahydrofuran solvent, measurement temperature 40 ° C.).

In particular, the sharper the molecular weight distribution, the better the performance tends to be, 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 further 1.9 or less. Preferably there is.

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
Cycloolefins such as norbornene and 2-acetyl-5-norbornene are mentioned, among which C _4-6.
Chain olefins, C _4-6 cycloolefins are prized.

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 to the olefin and radical polymerization may be performed, and the amount of the high-molecular-weight portion is further reduced. 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, (a) an alkali metal salt, ( b) Alkaline earth metal salt and (c) amine salt are used in the respective equivalent% of (a) 5 to 90, (b) 5 to 50 and (c) 1 to 9
0, preferably (a) 10-80, (b) 10-30 and (c)
It is necessary to adjust it to 5 to 60, and the effect of improving the strength is exhibited by using the above-mentioned three-component complex salt.

Specific examples of the alkali metal salt include lithium salt, sodium salt, potassium salt and the like, and among them, the sodium salt is most favored.

Alkaline earth metals include calcium, magnesium or barium, with calcium being the most preferred.

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 of amines include tertiary amines, especially triethanolamine.

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, 0.01 to 3% by weight, preferably 0.05 to 1% by weight
Used in proportion. 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 or kneading water, a method of simultaneously adding at the time of kneading a cement mixture such as concrete, a method of adding water or another admixture after starting stirring, are added. An example is a method of kneading the mixture in advance and then adding 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 portradon 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, it is possible to obtain a cement composition having good dispersion fluidity of cement and significantly suppressing slump deterioration and good workability, and also to obtain a cured product having 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 1 In an autoclave, a mixture of 98 parts of maleic anhydride, 76 parts of a C ₅ olefin mixture shown in Table 1, 4 parts of benzoyl peroxide and 400 parts of benzene under a nitrogen atmosphere at 70 to 75 ° C. The mixture was heated and stirred for a time to react. After completion of the polymerization reaction, the precipitated copolymer was separately collected and dried to obtain a C ₅ olefin-maleic anhydride copolymer.

Then, this copolymer was dissolved in methyl ethyl ketone and 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 in the copolymer thus obtained. The results are shown in Table 2.

Further, 300 parts of water was added to 100 parts of this copolymer, and 5.5 parts of calcium hydroxide was gradually added with stirring to dissolve it, and then 22.0 parts of triethanolamine and 47.2 parts of sodium hydroxide were added. An aqueous solution of the copolymer salt (I) was obtained by gradually adding and stirring the parts.

Table 1 iso-pentane about 16% n-pentane about 15% 2-methylbutene-1 about 42% pentene-1 about 27% isoprene 0.1% or less Reference Example 2 Calcium hydroxide 16.5 parts and triethanolamine 13
Except using 2 parts and 5.9 parts of sodium hydroxide,
By the same operation as in Reference Example 1, an aqueous solution of copolymer salt (II) was obtained.

Reference Example 3 An aqueous solution of a copolymer salt (III) was obtained in the same manner as in Reference Example 1 except that 6.2 parts of magnesium carbonate, 88 parts of triethanolamine and 41.4 parts of potassium hydroxide were used.

Reference Example 4 Triethanolamine 22 without using calcium hydroxide
An aqueous solution of copolymer salt (IV) was obtained by the same procedure as in Reference Example 1, except that 0 part was used.

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.

Reference Example 6 An aqueous solution of the copolymer (VI) was obtained 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.

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]

Prepare cement mortar with the following composition, JIS-R-52
Mortar test was carried out according to 01 (target flow 23
The amount of admixture added was adjusted to be 0 mm ± 5 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, in comparison with the comparative example, a small amount of the compound of the present invention can provide a cured product having good workability and high strength over a long period of time.

Example 2 Among the samples subjected to the mortar test in Example 1, copolymer salts (I), (III), (IV), (V) and (IV) were used for high strength concrete according to the following concrete test conditions. The composition was evaluated. The results are shown in Table 4.

[Concrete test] Cement, water, aggregate and hydraulic cement admixture were blended according to the following formulation, and after kneading with a forced kneading mixer for 90 seconds, slump and air amount were measured, and thereafter 30 minutes,
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 20 ±
The amount of admixture added was adjusted to be 1 cm. The measurement method is JIS A1101 for slump and JIS A111 for air volume.
6. The compressive strength was in accordance with JIS A1108. The concrete temperature is 20 ° C ± 2 ° C, and the sample for compressive strength measurement is 20 ± 2 ° C.
It was cured in water at ℃.

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), (I used in Example 2
With respect to V), (V) and (VI), 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 an α, β-unsaturated dicarboxylic acid and an olefin as an active ingredient, wherein the water-soluble salt is (a) an alkali metal salt 5 to 5.
An admixture for hydraulic cements, which is a complex salt consisting of 90 equivalent%, (b) 5 to 50 equivalent% of an alkaline earth metal salt, and (c) 1 to 90 equivalent% of an amine salt.