JPH01153558A - Admixture for cement - Google Patents

Abstract

PURPOSE:To obtain an admixture having excellent cement-dispersing performance and resistant to the lowering of workability with time, by reacting a neutralized product of a specific copolymer with a quaternarizing agent and using the obtained quaternary nitrogen-containing compound as a component. CONSTITUTION:The objective cement admixture contains a quaternary nitrogen- containing compound produced by neutralizing a copolymer of a vinyl compound and an ethylenic unsaturated dicarboxylic acid anhydride and having a molecular weight of 500-40,000 and reacting the neutralized product with a quaternarizing agent. The dissolution agent for neutralization is preferably a compound containing alkali metal or alkaline-earth metal, amine, ammonium or their mixture. Complete neutralization is preferable, however, a partially neutralized product having a neutralization degree of >=0.5 may be used. The quaternarizing agent used in the above process is preferably 2,3-epoxypropyl trialkyl ammonium chloride of formula (R1, R2 and R3 are 1-4C lower alkyl).

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an admixture for cement or cement mixtures, and more specifically, it improves the fluidity of mortar or concrete, which is a hydraulic cement mixture, and improves the fluidity over time. This prevents fluidity from decreasing and improves workability.
This invention relates to a cement admixture that can improve workability.

[Prior Art] Conventionally, cement mixtures made by mixing cement, water, and if necessary sand, gravel, admixtures, admixtures, etc., have been known to cause physical and chemical aggregation of cement particles over time. Fluidity is gradually lost, and workability and workability are reduced. Cement formulations therefore have the disadvantage of a relatively short and limited pot life. Cement mixtures are often transported by ready-mixed concrete mixer trucks from the ready-mixed concrete production factory to the pouring site, but the time it takes to arrive at the site varies greatly depending on the transportation distance and traffic conditions, so the ready-mixed concrete is transported at the pouring site. Each mixer truck receives a cement mixture with different fluidity, making it difficult to achieve consistent workability.

In addition, when applying cement mixtures, they are often pumped, but if the pumping is temporarily interrupted during breaks or during work procedures, and then restarted, the fluidity of the cement mixture decreases, causing the pumping pressure to drop. If it rises rapidly or becomes severe, problems such as blockage may occur.

For this reason, intensive research is being conducted to prevent the fluidity of cement mixtures from decreasing, and several methods have been proposed.

One method is to add a hardening retarder such as oxycarboxylic acid to prevent chemical agglomeration of cement particles. This method prevents physical agglomeration of cement particles,
It is difficult to prevent slump loss completely, and on the other hand, it has the disadvantage that the early strength of concrete and mortar decreases.

Another method is to prevent slump loss by granulating the fluidizing agent and adding it to mortar, concrete, etc. and gradually dissolving it. In this method, depending on the construction time, the granular fluidizing agent may remain undissolved locally in the concrete after hardening, and in this case, there will be drawbacks in terms of durability, etc.

Another method is to add a superplasticizer to the cement mixture in parts or continuously, which is effective as a method for preventing slump loss, but it is time-consuming to add the superplasticizer, and the above-mentioned pump pressure feeding method is effective. Due to problems such as not being able to be applied to cement mixtures, there are few examples of practical use.

Another method is to add a water-soluble polymer containing carboxylic acid in its molecules either alone or in combination with a conventional fluidizing agent. Although this method is also effective to some extent in preventing slump loss, On the other hand, the amount of air entrained increases and the strength of mortar or concrete decreases significantly, and there is also the side effect of delayed hardening, and in particular, a significant decrease in early strength is observed.

[Problems to be Solved by the Invention] As described above, conventional fluidizing agents have considerable problems, and solutions to these problems are desired.

An object of the present invention is to provide a fluidizing agent that has high performance in dispersing cement and exhibits less deterioration in workability over time.

[Means for solving the problem] As a result of intensive research to achieve the above object, the inventor of the present invention has developed a neutralized product of a copolymer of a vinyl compound and an ethylenically unsaturated dicarboxylic anhydride. The quaternary nitrogen-containing material obtained by reacting the quaternizing agent not only has the dispersion ability of the cement compound but also can prevent the workability from deteriorating over time, and the quaternary nitrogen-containing material can be used as a water reducing agent. The present invention was completed by discovering that the combined use of ``habo'' has the same effect as ``habo''.

That is, the gist of the first invention is that the molecular weight of the vinyl compound and the ethylenically unsaturated dicarboxylic anhydride is 500 to 500.
The gist of the invention of Bunch 2 is a cement admixture containing as a component a quaternary nitrogen-containing material obtained by reacting a quaternizing agent with a neutralized product of a copolymer of 40.000. and the ethylenically unsaturated dicarboxylic acid have a molecular weight of 50
A cement admixture containing a water reducing agent and a quaternary nitrogen-containing material obtained by reacting a quaternizing agent with a neutralized product of a copolymer having a molecular weight of 0 to 40,000.

The present invention will be explained in detail below.

Examples of the vinyl compound in the present invention include styrene,
α-methylstyrene, talolostyrene, vinyltoluene, methyl, ethyl, propyl, butyl, isobutyl, t
Examples include acrylic esters such as ert-butyl, 2-ethylhexyl, lauryl, benzyl, cyclohexy, and tetrahydrofurfuryl, methacrylic esters, vinyl acetate, vinyl propionate, vinyl chloride, vinyl bromide, acrylonitrile, and mixtures thereof. However,
Styrene is particularly preferred. Examples of the unsaturated dicarboxylic anhydride include maleic anhydride, itaconic anhydride, and citraconic anhydride, with maleic anhydride being particularly preferred. The molar ratio of the polymer of the vinyl compound and the ethylenically unsaturated dicarboxylic anhydride is preferably in the range of 4:6 to 6:4.

In the present invention, the molecular weight of the copolymer of the vinyl compound and ethylenically unsaturated dicarboxylic anhydride is 500 to 40.
A range of 000 is most preferred. If the molecular weight is smaller or larger than this range, the ability to disperse cement particles will be greatly reduced.

In the present invention, the solubilizing agent for neutralization is preferably a compound containing an alkali metal or alkaline earth metal, an amine, ammonium, or a mixture thereof, and the degree of neutralization is preferably complete neutralization, but neutralization is preferable. Partially neutralized products with a degree of 0.5 or more may be used.

In the present invention, the quaternizing agent is a compound of the general formula [where R, R and R3 are the same or different lower alkyl groups having 1 to 4 carbon atoms]. ] It is preferable to use 2,3-epoxypropyltrialkylammonium chloride, which easily undergoes an addition reaction with carboxylic acid groups in alkaline conditions and can introduce quaternary nitrogen into the molecule. It is.

The degree of quaternization is 0.005 to 0.5 based on the total carboxylic acid
If the degree of quaternization is more or less than this range, the dispersibility for cement particles and the ability to maintain workability will be insufficient for the purpose.

The present inventor further added and mixed a water reducing agent to a quaternary nitrogen-containing material obtained by reacting a quaternizing agent with a neutralized product of a copolymer of such a vinyl compound and an ethylenically unsaturated dicarboxylic anhydride. As a result, it was discovered that the workability and workability of cement mixtures could be further improved.

Water reducing agents used in the present invention include naphthalene sulfonic acid formaldehyde high condensate water reducing agents such as β-naphthalene sulfonic acid formaldehyde high condensates or salts thereof, and sulfonated melamine resin water reducing agents such as water-soluble salts of sulfonated melamine resins. and ligninsulfonic acid-based water reducing agents such as ligninsulfonic acid or its salts. Further, the proportion of the water reducing agent and the quaternary nitrogen-containing material obtained by reacting a quaternizing agent with a neutralized copolymer of a vinyl compound and an ethylenically unsaturated dicarboxylic anhydride is 0. 01
:99.99 to 90:10 (weight ratio) is preferable.

The cement admixture according to the present invention can be added to a cement mixture by dissolving it in kneading water or adding it to a cement mixture that has been kneaded. In addition, when using a water reducing agent together, both may be mixed in advance, or one may be mixed with cement, or one may be mixed with cement and kneaded before the other is mixed. .

The amount of the admixture of the present invention added to a cement mixture can be determined depending on the fluidity retention time of the mixture, and the normal use is in the range of 0.05 to 2% solid content based on the weight of cement. is preferred.

It is also possible to use it in combination with other cement additives, such as air entrainment agents, fluidizing agents, waterproofing agents, swelling agents, glass fibers, fly ash, slag, perlite, etc.

The cement mixture containing such a cement admixture according to the present invention can be cured by the usual method of curing mortar or concrete, and can also be cured by using methods such as steam curing or autoclave curing. .

It has not been known until now that the amphoteric polymer electrolyte of the present invention has a high-performance dispersion ability for cement particles and a function to prevent the workability of cement mixtures from decreasing over time, and therefore, its effect is also sufficient. is not clear. However, when describing the reasoning, it is said that for dispersion performance, it is preferable for the hydrophilic part and the hydrophobic part to exist in a certain ratio in the molecular structure, but the carboxyl group and trialkylammonia group are different from each other in the molecule. Because it forms a partially cross-linked structure within and between molecules, resulting in a large hydrophobic structure,
It is thought that this contributes to improving the dispersibility of cement particles.

In addition, cement particles are positively charged when unhydrated, but as the surface becomes hydrated, they become negatively charged, so trialkylammonia groups are effective in preventing cement particles from agglomerating over time, improving workability. It is thought that this prevents the decline.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example 1.2, Comparative Example 1] A copolymer of styrene and maleic anhydride (copolymerization molar ratio 1:1, average molecular weight ff 18,000) was used as a solubilizer and NaOH or NH4OH was used to dissolve each copolymer. The polymer was neutralized to a degree of neutralization of 0.7 to 1.0. Glycidyltrimethylammonium chloride was used as the quaternizing agent, and the reaction was carried out under weak alkalinity so that the degree of quaternization was 0.1 to 0.4 to obtain the corresponding quaternary nitrogen-containing products. .

Next, using concrete with the following materials and mix, JIS
A11 The fluidity of concrete was measured using the old slump test, and the results are shown in Table 1.

Materials used: Cement: Ordinary Portland cement Fine aggregate: Made in Kyōtsu (specific gravity 2.60, coarse grain ratio 2.69) Coarse aggregate: produced in Hanazono (specific gravity 2.79, coarse grain ratio 6.73, maximum dimension 20 mm) AE agent: Sunflow K (trade name, manufactured by Yamaba Kokusaku Valve ■) (blank below) The admixture shown in Table 2 was added to this at 0.2% of the weight of the cement, and the concrete performance was measured. It is shown in Table 2. Table 2 also shows the results of a concrete performance test as Comparative Example 1 using the same copolymer as in Example 1 except that the average molecular weight was 60.000 in Example 1 in Table 2. .

(Left below) As is clear from the experimental results shown in Table 2, in Example 1.2 using the product of the present invention, the slump of concrete
It shows a high value of 22.5 cm and maintains a high value of 20 cm or more even after 90 minutes, and has an extremely excellent fluidization effect and slump loss prevention effect.

On the other hand, in Comparative Example 1, the fluidization effect is low and the slump prevention effect is also insufficient.

[Example 3] The admixture used in Example 1 was added to the concrete shown in Table 1 in an amount of 0.05% of the cement weight, and the sodium salt of β-1 naphthalene sulfonic acid formaldehyde high condensate 1 was added to the concrete shown in Table 1. 0.15% was added and kneaded.

[Example 4] In Example 3, the same amount of sodium salt of sulfonated melamine resin was added instead of the sodium salt of β-naphthalene sulfonic acid (lumaldehyde condensate) and kneaded. Performance 1 to 3
Shown in the table.

(The following is a blank space) Table 3 [Effects of the Invention] The effects of using the cement admixture according to the present invention are that it can increase the fluidity of the cement mixture and keep the fluidity constant. This is the most specific point, and by simply adding a certain amount of the admixture according to the present invention to a ready-mixed concrete plant, it becomes possible to co-supply fluidized concrete of a certain quality to a construction site.

The present invention improves the fluidity of cement mixtures, and
The cement admixture according to the present invention can be used not only in the above-mentioned ready-mixed concrete plants, but also in concrete pumping aids, for example, because it can maintain constant fluidity and reduce the adverse effects of air inclusion and delay in facilitation. It can be used as an agent or centrifugal compaction aid, and it not only significantly increases work efficiency but also improves the performance of concrete.

Claims (1)

[Scope of Claims] 1. A quaternary compound obtained by reacting a quaternizing agent with a neutralized copolymer of a vinyl compound and an ethylenically unsaturated dicarboxylic acid anhydride having a molecular weight of 500 to 40,000. A cement admixture containing grade nitrogen-containing substances as an ingredient. 2. The cement admixture according to claim 1, wherein the dissolving agent for neutralization is a compound containing an alkali metal, an alkaline earth metal, an amine, ammonium, or a mixture thereof. 3. As quaternizing agents, there are general formulas ▲ mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, R_1, R_2 and R_3 represent the same or different lower alkyl groups having 1 to 4 carbon atoms. The cement admixture according to claim 1 or 2, which is 2,3-epoxypropyltrialkylammonium chloride represented by the following formula. 4. Degree of quaternization is 0.005 to 0 based on total carboxylic acids
．． 5. The cement admixture according to any one of claims 1 to 3. 5. A quaternary nitrogen-containing material obtained by reacting a quaternizing agent with a neutralized copolymer of a vinyl compound and an ethylenically unsaturated dicarboxylic acid having a molecular weight of 500 to 40,000, and a water reducing agent. A cement admixture containing. 6. The cement admixture according to claim 5, wherein the water reducing agent is one or more water reducing agents selected from naphthalene sulfonic acid formaldehyde high condensate type, sulfonated melamine resin type, and lignin sulfonic acid type. . 7. The combined use ratio of quaternary nitrogen-containing material and water reducing agent is 0.01:
The cement admixture according to claim 5 or 6, which has a weight ratio of 99.99 to 90:10.