JPS61209943A - Admixing agent for cement - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a novel admixture for hydraulic cement, and more specifically to a novel polymer admixture having excellent performance as a dispersant, water reducer, fluidizer, etc. This invention relates to an admixture for carboxylic acid-based hydraulic cement.

(Conventional technology) Generally, concrete, mortar, etc. using cement,
When producing pastes and the like, admixtures called dispersants, water reducers, or fluidizers are used. This admixture is expected to have the following effects. That is, (1) increasing the workability of unset cement formulations;

Also, 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. Also, if the strength is the same, the amount of cement used can be reduced. (3) Increase watertightness, etc.

Conventionally, specific examples of such admixtures include polyacrylic acid, polymaleic acid, olefin-α, β-unsaturated radicals, etc. Polycarboxylic acid admixtures such as carbonic acid copolymers are known (for example, JP-A-49-117519;
Special Publication No. 53-38095, U.S. Patent No. 3,943,0
No. 83, etc.).

But Cal like vinyl acetate? In the case of polycarboxylic acids copolymerized with unsaturated esters of phosphoric acid, the dispersibility of cement is poor (for example, JP-A-56-92154, JP-A-56-92154;
-128252), these types of copolymers are made by saponifying the ester portion or polymerizing in the coexistence of telodans such as sulfur-containing compounds and halogen-containing compounds. Without it, it could not be used as a cement admixture. Therefore, the production cost is higher than that of ordinary polycarboxylic acids, and the use of terodane increases air entrainment and reduces the strength of the cured product.

(Problems to be Solved by the Invention) The inventors of the present invention have conducted extensive studies to overcome these drawbacks of the prior art, and have found that unsaturated cal? α,β as acid
- Contrary to conventional knowledge, if an unsaturated monocarboxylic acid is used and a copolymer of a lower carboxylic acid unsaturated ester with a specific composition is used as an admixture, the dispersion fluidity of the cement is good, and The present inventors have discovered that it is possible to obtain a cement compound with good workability in which slump reduction is significantly suppressed, the amount of air entrained is also kept low, and a cured product with high strength can be obtained, leading to the completion of the present invention.

(Another Means to Solve the Problem) Thus, according to the present invention, 90 to 20 mol of α,β-unsaturated monocarboxylic acid and 1 mol of lower carbic acid unsaturated ester
There is provided an admixture for hydraulic cement characterized by containing 0 to 80 molar of a copolymer or a salt thereof as an active ingredient.

The copolymer used in the present invention has 90 to 20 moles of α,β-unsaturated heptanocarginic acid, preferably 85 to 30 moles of α,β-unsaturated heptanocarginic acid.
Molch, especially b) Lower carboxylic acid unsaturated ester 10~
80 mole, preferably 15 to 70 mole,
Usually, it 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 measured by high performance liquid chromatography (tetrahydrofuran solvent, measurement temperature 40° C.).

This copolymer is characterized by the use of unsaturated monocardic acid with a specific composition as the carboxylic acid component, and as a result, it is a non-air entraining cement mixer with excellent dispersion fluidity and slump retention. agent is obtained.

Specific examples of the above components (,) constituting the copolymer include:
Examples include acrylic acid, methacrylic acid, and crotonic acid, with acrylic acid and methacrylic acid being particularly industrially advantageous.

On the other hand, specific examples of the above-mentioned (bJ&min) include vinyl acetate, vinyl propionate, vinyl butyrate, and acetic acid, among which vinyl acetate is particularly popular.

In addition, within the range that does not essentially impair the effects of the present invention,
Vinyl monomers such as 7'tene, pentene, hexene, styrene, methyl methacrylate, methyl vinyl ether, ethylene sulfonic acid, etc. may be copolymerized, and a portion of the carboxyl groups in the copolymer may be esterified to diamidate. It can also be used as

The method for producing the copolymer used in the present invention is not particularly limited, and may be carried out according to conventional methods.

For example, a comonomer can be obtained by charging α,β-unsaturated monocargenic acid and unsaturated lower cargenic acid ester in a predetermined ratio and radically polymerizing the mixture in an organic solvent.

If the produced copolymer itself is water-soluble, it can be used as is, but usually some or all of the carboxyl groups present in the copolymer are converted into salts with monovalent or polyvalent cations. , used to enhance bathing ability. Specific examples of such salts include salts of alkali metals or alkaline earth metals such as sodium, potassium, magnesium, calcium, barium, etc., ammonium salts, amine salts such as trimethylamine, triethylamine, triethanolamine, etc., and salts of these salts. Examples include complex salts, among which alkali metal salts are the most prized from the standpoint of economy, stability, and dispersibility.

Further, its usage form is not particularly limited, and it can be used in the form of a bath liquid or a solid form such as a powder, and can be used alone or in combination with other cement admixtures. Examples of cement admixtures that can be used in combination include conventional cement dispersants, air entraining agents, cement wetting and dispersing agents, swelling agents, waterproofing agents, strength enhancers, hardening accelerators, setting accelerators, setting retarders, etc. .

The amount of the cement admixture of the present invention to be used may be appropriately selected depending on the required performance, but based on the solid content of cement,
Usually, it is used in a proportion of 0.01 to 3% by weight, preferably 0.05 to 1% by weight. As the amount used decreases, the effect of improving workability decreases, and on the other hand, if the amount used is excessive, it may have a negative effect on cement hardening.

Furthermore, the timing of addition to the cement mixture can be selected as appropriate depending on the intended use. Specific methods include, for example, mixing it with cement in advance, adding it at the same time when mixing cement mixtures such as concrete, adding it after adding water or other admixtures and starting stirring, and adding it in advance. An example is a method of post-adding at an appropriate interval after the formulation HD is prepared.

The types of cement to which the hydraulic cement admixture of the present invention can be applied are not particularly limited, and specific examples thereof include ordinary Portland cement, half-arc 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, it is possible to obtain a cement admixture that has good dispersion fluidity and slang retention of cement and has a small amount of air entrainment.

(Example) EXAMPLES The present invention will be specifically described below with reference to Examples.

Note that parts and parts in Examples and Reference Examples are based on weight unless otherwise specified.

Reference Example A mixed solution of unsaturated monocarmenic acid, 90 cs of toluene and 10 g of Inflo/Gnol was placed in a flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, and heated to 80°C after purging with nitrogen. did. Then vinyl acetate and α, α
A toluene solution of '-azobisinbutyronitrile was added dropwise while stirring, and after the addition was completed, the temperature was kept at 80°C for 3
Allowed time to react. The monomer concentration was about 20%, and the amount of catalyst used was about 4.3% based on monomer.

After the reaction was completed, the solvent and unreacted upper residue were distilled off, washed with ethyl ether, and dried under reduced pressure to obtain a polymer. The properties of the polymer are shown in Table 1.

Table 10 Example 1 The performance of the hydrolyzate (sodium salt) of the polymer having the composition shown in Table 1 obtained in Reference Example as a hydraulic cement admixture was evaluated according to the mortar test conditions described below. The results are shown in Table 2.

[Mortar test]

Prepare cement mortar with the following composition and use it according to JIS-R-
A mortar test was carried out according to JIS-A-1116 (the amount of admixture added was adjusted so that the target flow was 230±5cm).The amount of air entrainment was measured according to JIS-A-1116. The mortar temperature was 20±2°C, and the temperature during underwater curing for measuring compressive strength was 20±2°C.

Mixed cement: 600 parts Asano ordinary Portland cement sand: 1200 parts Industrial sand water for Oi: 210 parts (Total amount including water in the admixture below) Cement admixture: As shown in Table 2, cement/sand ratio = 1/2 Cement/water ratio == 110.35 From Table 2, it can be seen that the product of the present invention can provide good workability over a long period of time even when a small amount is added, and the amount of air entrainment is also small. It can also be seen that good results are obtained in terms of compressive strength development performance after curing.

Example 2 The copolymer ω) used in Example 1 and the sodium salt of (1) were evaluated for general concrete formulations using the following concrete formulations. The results are shown in Table 3.

[Concrete test]

After mixing cement, water, aggregate, and hydraulic cement admixture according to the following formula, kneading with a forced wire mixer for 90 seconds, measuring slump and air content, and then mixing for 30 minutes.
After 60 minutes had elapsed, the mixture was kneaded again, and the slump and air content were measured. A sample for compressive strength measurement was taken after 60 minutes. The slump target immediately after training is slump 20±
The amount of admixture added was adjusted to 1 crn. The measurement method is JISAIIOI for slump and JISA1116 for air volume. The compressive strength was in accordance with JISA1108. The concrete temperature was 20±2°C, and the sample for compressive strength measurement was cured in water at 20±2°C.

Concrete mixing volume slan f: 10 ± 1 m Target air volume = 4.5 ± 0.5% (Air volume control Vinsol: Yamasou Kagakusha) Table 3 $1 Commercially available lignin sulfonate (Boris + 5 L, 1 day) Master Builders Co., Ltd.) Table 3 shows that even in concrete formulations for general use, it exhibits good performance with a lower additive amount than conventional products, and the strength of the cured product is also good.

Claims (1)

[Claims] 1. Hydraulic cement containing a copolymer of 90 to 20 mol% of α,β-unsaturated monocarboxylic acid and 10 to 80 mol% of lower carboxylic acid unsaturated ester or a salt thereof as an active ingredient Admixture.