JPH0688819B2 - 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.

Heretofore, as specific examples of such an admixture, polyacrylic acid, polymaleic acid, polyethylene sulfonic acid and the like have been known (for example, JP-A-49-117519 and JP-A-57-156355).
No. 3, U.S. Pat. No. 3,943,083).

However, these admixtures have merits and demerits in terms of dispersion fluidity, slump retention, air entrainment, cement hardening time, etc. depending on the composition of the polymer, and development of a higher performance admixture has been desired.

(Problems to be solved by the invention) Therefore, as a result of intensive investigations by the present inventors to overcome such drawbacks of the prior art, when a specific copolymer is used as an admixture, the dispersion fluidity of cement is improved. It was found that a cement mixture with good workability and good suppression of slump deterioration was obtained, and the amount of air entrained was also suppressed to be low, and a cured product with high strength was obtained.
The present invention has been completed.

(Means for Solving the Problems) Thus, according to the present invention, α, β-unsaturated dicarboxylic acid
There is provided an admixture for hydraulic cement, which comprises a copolymer of 90 to 20 mol% and an aliphatic unsaturated sulfonic acid 10 to 80 mol% or a salt thereof as an active ingredient.

The copolymer used in the present invention is (a) β, β-unsaturated dicarboxylic acid 90 to 20 mol%, preferably 80 to 30 mol% and (b) aliphatic unsaturated sulfonic acid 10 to 80 mol%, It preferably comprises 20 to 70 mol% and usually has a number average molecular weight of 300 to 20,000, preferably 1,000 to 10,000.

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

Such a copolymer is characterized in that unsaturated dicarboxylic acid and unsaturated sulfonic acid are used together as constituent components in a specific ratio, and as a result, dispersion fluidity and slump retention are excellent in non-air entrainment. A strong cement admixture is obtained.

Specific examples of the component (a) constituting the copolymer include:
Examples thereof include maleic acid, itaconic acid, fumaric acid, citraconic acid, and their anhydrides, with maleic anhydride being industrially advantageous.

On the other hand, specific examples of the component (b) include ethylene sulfonic acid, allyl sulfonic acid, etc. Among them, allyl sulfonic acid is preferred.

Further, within the range that does not substantially impair the effects of the present invention,
Butene, pentene, hexene, styrene, vinyl acetate,
Vinyl monomers such as methyl methacrylate and methyl vinyl ether may be copolymerized, and a part of the carboxyl group and / or acid anhydride group in the copolymer may be esterified or amidated for use.

The method for producing the copolymer used in the present invention is not particularly limited, and it is carried out according to a conventional method. For example, α, β
-A copolymer is obtained by charging an unsaturated carboxylic acid and an aliphatic unsaturated sulfonic acid in a predetermined ratio and radically polymerizing them in an aqueous solution or an organic solvent.

When the produced copolymer is water-soluble by itself, it can be used as it is, but usually, a part or all of the sulfonic acid group, carboxyl group and / or acid anhydride group present in the copolymer are used. Is salted with a monovalent or polyvalent cation to enhance the water-solubilizing ability. Specific examples of such salts include salts of alkali metals or alkaline earth metals such as sodium, potassium, magnesium, calcium, barium, ammonium salts, amine salts such as trimethylamine, triethylami, triethanolamine, and salts thereof. Examples thereof include complex salts, and among them, alkali metal salts are most favored from the viewpoints of economy, safety, dispersibility and the like.

The form of use is not particularly limited, and it may be used in the form of an aqueous solution or a solid form such as a powder, and may 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, expanding agents, waterproofing agents, strength enhancers, hardening accelerators, setting accelerators, setting retarders and the like. .

The amount of the admixture for hydraulic cement of the present invention to be used may be appropriately selected according to the required performance, but is usually 0.01 to 3% by weight, preferably 0.05 to 1% by weight based on the solid content relative to the cement. used. As the amount used decreases, the workability improving effect decreases, and conversely, if 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. Specific methods thereof include, 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 premixing. An example of such a method is to knead the product and then add it at an appropriate interval.

The type of cement to which the admixture for hydraulic cement 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 boltland cement, and alumina cement,
Examples include fly ash cement, blast furnace cement, silica cement, slag cement, and various mixed cements.

(Effects of the Invention) Thus, according to the present invention, it is possible to obtain a cement admixture having excellent dispersion fluidity and slump retention of cement and having a small air entrainment amount.

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

Example 1 The performance of a sodium salt of a polymer having the composition shown in Table 1 obtained by radical polymerization as an admixture for hydraulic cement was evaluated according to the following mortar test conditions. The results are shown in Table 2.

[Mortar test]

The cement mortar with the following composition was adjusted, and the mortar test was carried out according to JIS-R-5201 (the admixture additive amount was adjusted so that the target flow rate was −230 ± 5 mm). -Measured according to A-1116. The mortar temperature was 20 ± 2 ° C, and the temperature in water curing for measuring the compressive strength was 20 ± 2 ° C.

Blended cement: 600 parts Asano ordinary Portland cement Sand: 1200 parts Oigawa-produced river sand Water: 210 parts (total amount including water in the admixture below) Admixture for cement: As shown in Table 2 Cement / sand ratio = 1/2 Cement / water ratio = 1 / 0.35 It can be seen from Table 2 that the product of the present invention can provide good workability over a long period of time even with a small amount of addition, and has a small amount of air entrainment. Further, it can be seen that good results are obtained in terms of the compressive strength development performance after curing.

Example 2 The sodium salts of the copolymers (II) and (III) used in Example 1 were evaluated for the general concrete mix by the following concrete mix. The result is the third
Shown in the table.

[Concrete test]

Cement, water, aggregate and admixture for hydraulic cement according to the following formulation, after kneading with a forced kneading mixer for 90 seconds, slump, measure the air amount, after 30 minutes, 60
After the lapse of minutes, the mixture was kneaded again, and the slump and the air amount were measured. After 60 minutes, a sample for compressive strength measurement was taken. The amount of admixture added was adjusted so that the slump target immediately after kneading was 20 ± 1 cm. Regarding the measuring method, JIS A1101 was used for the slump, JIS A1116 was used for the amount of air, and JIS A11108 was used for the compressive strength.

The concrete temperature was 20 ± 2 ° C, and the sample for compressive strength measurement was aged in water at 20 ± 2 ° C.

From Table 3, it can be seen that even in the case of the concrete mix for general use, good performance is exhibited with a low addition amount as compared with the conventional product and the strength of the cured product is also good.

Claims (1)

[Claims] 1. An α, β-unsaturated dicarboxylic acid 90 to 20 mol%
An admixture for hydraulic cement, which comprises a copolymer of 10 to 80 mol% of aliphatic unsaturated sulfonic acid or a salt thereof as an active ingredient.