JPH0570198A - Cement admixture - Google Patents

Abstract

PURPOSE:To provide a cement admixture enhancing the flowability of a cement mixture, reduced in the amount of entrained air and effective for preventing the slump loss of the cement product. CONSTITUTION:A cement mixture containing at least one salt selected from the group consisting of alkali metal salts, ammonium salts and amine salts derived from a copolymer obtained by reacting a light oil fraction containing indene as a main component with an unsaturated dicarboxylic acid anhydride having an olefinic double bond, the component having a mol. wt. of <=2000 being contained in the salt in an amount of <=4.0 area % measured by a gel- permeation chromatography method. At least one kind of the salt selected from a naphthalenesulfonic acid-formaldehyde condensation product salt, a melamine resin sulfonate salt, and a lignin sulfonate salt may further be added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an admixture for cement which hardens under the influence of water, and is capable of fluidizing cement paste, mortar or concrete, which is a cement compound, and maintaining its fluidity for a predetermined time. The present invention relates to a cement admixture which can be produced and has a small air entrainment amount in a cement composition.

[0002]

2. Description of the Related Art In order to improve the workability of cement paste, mortar or concrete, which is a cement mixture, it is necessary that the initial cement mixture has a high fluidity and that the fluidity is less likely to decrease with time. ..

Cement paste, which is a cement formulation,
Mortar or concrete, due to the hydration reaction of cement and water, the physical and chemical agglomeration of cement particles progresses with the passage of time after kneading, so the fluidity decreases, and the workability and workability are deteriorated over time. Decrease. This phenomenon generally limits the flow of mortar and the working pot life of concrete, called slump loss.

[0004] In the case of ready-mixed concrete, slump loss of concrete causes problems such as limitation of transportation time, waiting time at the setting site, quality deterioration due to temporary interruption of pumping, and defective construction.

Also in the case of secondary concrete products,
Due to the slump loss of concrete, the molding time is limited and centrifugal compaction is poor.

Therefore, the change with time of fluidity of cement paste, mortar or concrete which is a cement mixture, that is, slump loss, is an important problem to be solved.

[0007] It is also preferable that the cement admixture entrain a small amount of air in the cement mixture. This is to obtain a cement composition with a wide range of air amount adjustment when it is applied.

The inventors of the present invention firstly mixed cement with an essential component of a copolymer obtained by the reaction of a light oil component containing indene as a main component with an unsaturated dicarboxylic acid anhydride having an olefinic double bond. The agent is effective in preventing slump loss, and when this cement admixture is added, the initial fluidity is high, the amount of air entrained is small, and this cement admixture is less expensive than cheap coal and petroleum by-product oil. Since it is manufactured, it was found to be economically advantageous as compared with other cement admixtures, and a patent application was filed (Japanese Patent Laid-Open No. 1-176256).
issue).

However, when the cement admixture is added excessively or when a specific fine aggregate is used in mortar and concrete, the amount of air entrained in the cement mixture is increased and the amount of air at the time of construction is increased. There was a problem that the adjustment range became narrow.

[0010]

DISCLOSURE OF THE INVENTION The present invention is a cement containing as an essential component a copolymer obtained by reacting a light oil containing indene as a main component with an unsaturated dicarboxylic acid anhydride having an olefinic double bond. Related to admixture, which solves the above-mentioned problems of the prior art, aims to provide a cement admixture that enhances the fluidity of the cement mixture, has a small amount of air entrainment, and is effective in preventing slump loss. To do.

[0011]

Means for Solving the Problems As a result of intensive studies by the present inventors to reduce the amount of air in a cement mixture, the amount of air in the cement mixture was found to be such that a light oil component containing indene as a main component and an olefin. Of a low molecular weight component in the salt derived from the copolymer obtained by the reaction with an unsaturated dicarboxylic acid anhydride having a polymerizable double bond, and a low molecular weight in the salt derived from the copolymer. By reducing the amount of components to below a specific amount, the amount of air entrained in the cement mixture is small, and while cement paste, mortar or concrete which is a cement mixture is fluidized, its fluidity is maintained for a predetermined time. The present invention has been completed by finding that a cement admixture that can be retained is obtained.

That is, according to the first aspect of the present invention, an alkali metal derived from a copolymer obtained by the reaction of a light oil component containing indene as a main component with an unsaturated dicarboxylic acid anhydride having an olefinic double bond. A salt containing at least one salt selected from the group consisting of salts, ammonium salts and amine salts, and a component having a molecular weight of 2000 or less in the salt is 4.0 as determined by gel permeation chromatography.
Provided is a cement admixture characterized by having an area% or less.

According to the second aspect of the present invention, it is derived from a copolymer obtained by the reaction of a light oil component containing indene as a main component with an unsaturated dicarboxylic acid anhydride having an olefinic double bond. It is at least one salt selected from the group consisting of alkali metal salts, ammonium salts and amine salts, and a component having a molecular weight of 2000 or less in the salt is 4.0 as determined by gel permeation chromatography.
At least 1 selected from those having an area% or less, a salt of a naphthalenesulfonic acid formaldehyde condensate, a salt of a melamine resin sulfonic acid, and a salt of ligninsulfonic acid.
Provided is a cement admixture characterized by containing a seed salt.

The present invention will be described in more detail below. The light oil containing indene as a main component has a boiling point range of about 150 to 250 obtained in the coal tar distillation / fractionation step.
℃ heavy gas oil (hereinafter referred to as coal tar naphtha fraction,
Examples include a fraction obtained by removing benzene, toluene, xylene, etc. from coke oven gas gas oil (commonly known as CN oil) (commonly known as C ⁹⁺ oil) and a petroleum-based C ⁹⁺ fraction.
It is preferable that the content is at least wt%. When the indene content is low, the indene content can be adjusted to 25% by weight or more by a simple distillation operation.

In addition to indene, these light oils contain
It may contain coumarone, dicyclopentadiene, styrene, methylindene and the like. Moreover, you may use it, after performing various pre-processing.

Examples of unsaturated dicarboxylic acid anhydrides having an olefinic double bond include maleic anhydride and itaconic anhydride, with maleic anhydride being preferred.

Any method may be used for producing the above-mentioned copolymer of a light oil containing indene as a main component and an unsaturated dicarboxylic acid anhydride having an olefinic double bond.
For example, a coal tar naphtha fraction and maleic anhydride are reacted in the presence or absence of a radical polymerization initiator under radical polymerization conditions to form a copolymer.

The above copolymer is not used as it is, but the acid anhydride portion of the copolymer is reacted with a basic substance in order to exert a dispersing effect quickly and to make it water soluble.
Used as salt. Examples of such salts include alkali metal salts such as sodium and potassium, ammonium salts or amine salts, or a mixture thereof, but it is preferable to use them as sodium salts.

The alkali metal salt or ammonium salt of the copolymer may be neutralized with sodium hydroxide, potassium hydroxide, aqueous ammonia or the like. Also, to make an amine salt,
The carboxylic acid of the copolymer obtained by hydrolysis or the like may be treated with amines.

The reaction of the acid anhydride portion of the copolymer may be carried out for all of them, but the acid anhydride portion may partially remain as the acid anhydride.

The component having a molecular weight of 2000 or less in the salt of the copolymer must be 4.0 area% or less as measured by the GPC method described below.

The molecular weights shown here are measured by gel permeation chromatography (GPC method) and expressed in terms of sodium polystyrene sulfonate. That is, GP
The molecular weight distribution curve of the copolymer salt measured by the C method is divided by the molecular weight of 2,000 converted to sodium polystyrene sulfonate, and the portion having a molecular weight of 2000 or less is represented by the area% of the total amount of the salt derived from the copolymer. The conditions for measuring the molecular weight distribution of the salt derived from the copolymer by the GPC method are as follows. Column: Tsk-gel G4000SW + Tsk-gel G3000SW (each 7.6 mmφ × 600 mm, manufactured by Tosoh Corporation) Mobile phase: 0.05 M sodium acetate aqueous solution / acetonitrile = 60/40 (vol / vol) Temperature: 40 ° C. Flow rate: 0 80 (ml / min) Detector: UV absorptiometer (254 nm) Standard substance: Sodium polystyrene sulfonate (Pressu
re Chemical)

Molecular weight 200 in salts derived from copolymers
There is a correlation between the component amount of 0 or less and the air amount in the cement mixture, and the molecular weight in the salt derived from the copolymer is 2000.
When the amount of the following components increases, the amount of air increases. Therefore, when a copolymer salt in which the component having a molecular weight of 2000 or less exceeds 4.0 area% is used, the amount of air in the cement mixture increases, and the control range of the amount of air at the time of construction becomes narrow. In particular, the excessive addition of salts derived from these copolymers,
Alternatively, by using a specific fine aggregate in mortar and concrete, this adverse effect becomes remarkable.

Molecular weight 200 in salts derived from copolymers
In order to reduce the content of components of 0 or less to 4.0% by area or less, methods such as removal of low molecular weight components by ultrafiltration and purification by difference in solubility in various solvents can be used, but any other method is adopted. Good. Further, the above method may be adopted in any state of the copolymer before conversion into a salt or the salt derived from the copolymer.

The cement admixture of the present invention contains a salt derived from a copolymer having a component having a molecular weight of 2000 or less as described above and having a molecular weight of 2000 or less at 4.0% by area or less, and further a salt of a naphthalenesulfonic acid formaldehyde condensate. At least one sulfonate salt selected from sulfonic acid salts of melamine resins and ligninsulfonic acid salts can be included.

Examples of salts of naphthalene sulfonic acid formaldehyde condensate, sulfonic acid salts of melamine resin, and salts of lignin sulfonic acid include alkali metal salts such as sodium and potassium. The mixing ratio of the sulfonate and the salt derived from the copolymer is 1 sulfonate.
The amount of the salt derived from the copolymer is preferably 5 to 50 parts by weight with respect to 00 parts by weight.

The cement admixture of the present invention is used in the range of 0.01 to 1.0% by weight with respect to cement.
0.1 to 0.5% by weight is particularly preferred. Addition amount is 0.0
If it is less than 1% by weight, the initial fluidity is insufficient, and if it exceeds 1.0% by weight, there is almost no change in the performance and the economy is deteriorated.

The cement admixture of the present invention may be added to the water for kneading the cement mixture or may be added to the cement mixture once kneaded. In the case of an admixture that uses a salt derived from a copolymer and a sulfonate, each may be added separately to kneading water or a cement mixture that has been kneaded, or both may be mixed in advance. it can.

The cement admixture of the present invention may be used in combination with various cement additives such as an AE agent, an AE water reducing agent and a setting modifier.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not particularly limited thereto.

1. Mortar Evaluation (Example 1) 50 or more polymerizable components such as indene and coumarone were used.
% Of the coal tar naphtha fraction having an indene content of 37.3% by weight and maleic anhydride as a radical initiator of azobisisobutyronitrile (1.00 mol% relative to (polymerization component + maleic anhydride Acid)) was used to react the above-mentioned polymerization components with maleic anhydride at a molar ratio of 1: 1 and the resulting copolymer was neutralized with sodium hydroxide to obtain an aqueous sodium salt solution of the copolymer. .. When the molecular weight was measured by gel permeation chromatography, the weight-average molecular weight of 28,000 and the components having a molecular weight of 2000 or less were 8.0 area%.

The low molecular weight component of the aqueous sodium salt solution of this copolymer is subjected to ultrafiltration (filtration membrane: ultrafilter Q
0100, manufactured by Advantech Toyo Co., Ltd., to obtain a cement admixture having 2.8 area% of components having a molecular weight of 2000 or less.

This cement admixture was added to mortar having the materials and compounding compositions shown in Table 1 and subjected to a mortar test. Cement: Ordinary Portland Cement (manufactured by Mitsubishi Mining Cement Co., Ltd.) Sand: Aichigawa, Shiga Prefecture (specific gravity of dry surface: 2.62, F
M: 2.80) Water: Well water

That is, the cement mixing honey,
Water, cement and admixture (0.5% by weight in terms of solid content)
Cement) was added and mixed with a paddle for 30 seconds, then sand was added while mixing for 30 seconds, followed by mixing for 60 seconds. After leaving still for 20 seconds to scrape off the mortar adhered to the mixing bee and the paddle, the mixture was mixed again for 120 seconds.

After the mortar was packed in a mini slump cone having a height of 15 cm, the mini slump cone was removed and the slump was measured and found to be 9.4 cm.

Mortar with a height of 9.5 cm and an inner diameter of 8.2 c
After packing in a metal cylinder of m, the weight was measured and the amount of air in the mortar was calculated to be 4.2%.

After leaving the mortar still for 60 minutes, 1
After mixing for a minute and measuring the slump in the same manner, it was 8.5.
It was cm.

When the slump residual rate (%) was calculated by the following formula, it was 90%. Slump residual rate (%) = ((slump value (after 60 minutes))
/ (Slump value (after 0 minutes)) x 100

Example 2 Obtained in the same manner as in Example 1,
A molecular weight of 2000 is obtained by ultrafiltration of an aqueous solution of sodium salt of a copolymer having a weight average molecular weight of 28,000 and a molecular weight of 2000 or less of 8.0 area% (ultrafilter Q0100, manufactured by Advantech Toyo Co., Ltd.).
The same procedure as in Example 1 was carried out except that a cement admixture having the following components of 4.0 area% was used. The results are shown in Table 2.

Comparative Example 1 Obtained in the same manner as in Example 1,
The same procedure as in Example 1 was carried out except that an aqueous solution of sodium salt of a copolymer having a weight average molecular weight of 28,000 and a molecular weight of 2000 or less and 8.0 area% was used as a cement admixture.
The results are shown in Table 2.

Example 3 Obtained in the same manner as in Example 1,
Mixing a sodium salt aqueous solution of a copolymer having a molecular weight of 2000 or less with 2.8 area% and a salt (sodium salt) of a naphthalenesulfonic acid formaldehyde condensate at a ratio of 4: 6 (weight ratio in terms of solid content). Then, the same procedure as in Example 1 was carried out except that the cement admixture was obtained, and the results are shown in Table 2.

Comparative Example 2 Obtained in the same manner as in Example 1,
A weight-average molecular weight of 28,000 and a component having a molecular weight of 2000 or less of 8.0 area% of a sodium salt aqueous solution of a copolymer and a salt of a naphthalenesulfonic acid formaldehyde condensate (sodium salt) were mixed at a weight ratio of 4: 6 (solid content conversion ratio). ) Were mixed to obtain a cement admixture, and the same operation as in Example 1 was carried out. The results are shown in Table 2.

Comparative Example 3 The same procedure as in Example 1 was carried out except that a salt (sodium salt) of a naphthalenesulfonic acid-formaldehyde condensate was used as a cement admixture, and the results are shown in Table 2.

Example 4 In the same manner as in Example 1, a copolymer of a polymerizable component such as indene and coumarone and maleic anhydride (hereinafter abbreviated as a copolymer) was obtained. The above copolymer 1
0 parts by weight of a mixed solvent (hexane / acetone = 8/2 (v
/ V)) After washing with 100 ml, the components having a molecular weight of 2000 or less are 3.
A cement admixture of 8 area% was obtained. A mortar test was conducted in the same manner as in Example 1, and the results are shown in Table 2.

(Example 5) A cement admixture having a molecular weight of 2000 or less and an area of 3.0 area% was obtained by using a mixed solvent (hexane / acetone = 5/5 (v / v)) as a washing solvent. The same operation as in Example 4 was carried out except that the result was shown in Table 2.

(Example 6) A cement admixture containing 4.0 area% of components having a molecular weight of 2000 or less obtained by using a mixed solvent (hexane / methyl ethyl ketone = 8/2 (v / v)) as a washing solvent. The same operation as in Example 4 was carried out except that the result was shown in Table 2.

Example 7 Obtained in the same manner as in Example 5,
An aqueous solution of a sodium salt of a copolymer having a molecular weight of 2000 or less of 3.0 area% and a salt of a naphthalenesulfonic acid formaldehyde condensate are 4: 6 (weight ratio in terms of solid content).
The same procedure as in Example 1 was carried out except that the cement admixture was obtained by mixing at a ratio of 1., and the results are shown in Table 2.

[0048]

[Table 1]

2. Concrete Evaluation With respect to the cement admixture obtained by the present invention, the fluidity retention was also evaluated by the concrete that is often used actually.

(Example 8) The cement admixture obtained in the same manner as in Example 3 was added to concrete having the composition shown in Table 3, and the slump was measured and evaluated according to JIS A 1101.

[0051]

[Table 2]

That is, a forced kneading mixer (internal volume 50
L), a cement admixture (0.6% by weight in terms of solid content relative to cement), water, cement, fine aggregate and coarse aggregate are mixed for 2 minutes, and then discharged into a kneading vat for kneading. When it was returned and the slump was measured, it was 20.0c.
It was m. This concrete was allowed to stand and repeated every predetermined time, and the slump was measured. The results are shown in FIG.

Comparative Example 4 Using the cement admixture obtained in the same manner as in Comparative Example 2, concrete was evaluated in the same manner as in Example 8, and the results are shown in FIG. From FIG. 1, the shunrap residual rate is almost the same as that of Example 8, but comparing the air amounts of Example 3 and Comparative Example 2 which are respectively corresponding mortar tests, Example 8 has a smaller air entrainment amount. Can be predicted.

Comparative Example 5 Using the cement admixture obtained in the same manner as in Comparative Example 3, the concrete was evaluated in the same manner as in Example 8, and the results are shown in FIG. In Example 3 and Comparative Example 3 in Table 2 which are corresponding mortar tests, the air entrainment amount is almost the same, but it can be understood from FIG. 1 that Example 8 has a larger slump residual rate.

[0055]

INDUSTRIAL APPLICABILITY The novel cement admixture of the present invention, when used in a cement mixture, has high initial fluidity, low air entrainment, and retains the fluidity of the cement mixture. It is useful as an additive to cement formulations such as.

If the cement admixture of the present invention is used, a cement mixture having a wide range of air content can be obtained by adjusting at the time of construction.

[Brief description of drawings]

FIG. 1 is a graph showing changes over time in slumps of Example 8 and Comparative Examples 4 and 5.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshihiro Naruse 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Division (72) Inventor Kimiyo Otsu 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Stock Technology Research Division

Claims (2)

[Claims] 1. An alkali metal salt derived from a copolymer obtained by the reaction of a light oil mainly containing indene and an unsaturated dicarboxylic acid anhydride having an olefinic double bond,
It contains at least one salt selected from the group consisting of ammonium salts and amine salts, and has a molecular weight of 2000.
A cement admixture characterized in that the following components are 4.0 area% or less as measured by gel permeation chromatography. 2. An alkali metal salt derived from a copolymer obtained by the reaction of a light oil containing indene as a main component with an unsaturated dicarboxylic acid anhydride having an olefinic double bond,
At least one salt selected from the group consisting of ammonium salts and amine salts, wherein the salt has a molecular weight of 2000.
At least one selected from the following components in an amount of 4.0 area% or less as determined by gel permeation chromatography, a salt of a naphthalenesulfonic acid formaldehyde condensate, a salt of a sulfonic acid of a melamine resin, and a salt of ligninsulfonic acid. A cement admixture containing one kind of salt.