JPH0248450A - Admixture for cement - Google Patents

Abstract

PURPOSE:To provide the title admixture capable of giving excellent fluidity drop-off-preventiveness when incorporated into cement, comprising a specific water-insoluble polymer and/or water-insoluble metal complex of polymer and a OH group-contg. water-soluble polymer. CONSTITUTION:The objective admixture comprising (A) (A1) a water-insoluble polymer 500-50000 in molecular weight, 0.1-2mu in mean particle size, having in the molecule carboxyl group [e.g., a copolymer consisting mainly of 2-8C olefin (e.g., isobutylene) and ethylenic unsaturated dicarboxylic anhydride (e.g., maleic anhydride)] and/or (A2) a water-insoluble metal complex 0.1-20mu in mean particle size, formed from a polymer 500-50000 in molecular weight having in the molecule carboxyl group [e.g., (meth)acrylic acid homopolymer] and a divalent metal (e.g., Zn) and (B) a OH group-contg. water-soluble polymer (e.g., water-soluble starch). The weight ratio A/B is such as to be as follows: 0.1-20 pts.wt. of the component B per pt.wt. of the component A1 and/or component A2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to admixtures for cement or cement mixtures, and more particularly to improving the workability of concrete, mortar or paste, which are hydraulic cement mixtures. This invention relates to a cement admixture that prevents deterioration over time and improves its workability and workability.

[Conventional technology]

Conventionally, cement mixtures are made by mixing cement, water, sand, gravel, and admixtures. gradually loses its fluidity, reducing workability and workability.

For this reason, the cement compound has a workable time (pot life).
It has the disadvantage of being limited.

In order to solve these problems, various methods have been proposed to prevent deterioration in workability of cement mixtures. for example,
Micronized copolymers of lower olefins and maleic anhydride (for example, Japanese Patent Publication No. 63-5346) and insoluble metal complexes of ethylenically unsaturated dicarboxylic acid copolymers (
By blending JP-A No. 62-83344) into cement, it becomes water-soluble through a reaction with the alkali in the cement, and is adsorbed onto the cement to gradually improve fluidity, resulting in long-term fluidity. There is a way to keep it.

[Problem to be solved by the invention]

However, with the above method, it is difficult to suppress the consumption of dispersant over time accompanying the hydration reaction of cement, and a decrease in workability is unavoidable. In order to completely suppress this decrease in workability, it is necessary to increase the amount added more than necessary. However, this excessive addition is not only uneconomical but also has the disadvantage of causing significant curing retardation.

[Means for Solving the Problems] The present invention has been made to improve the problems of the conventional methods described above.
00 to 50,000 and an average particle size of 0.1 to 20 μm, and/or a water-insoluble polymer with a molecular weight of 500 to 50,000 having a carboxyl group in the molecule and a divalent metal with an average particle size of 0.00 to 50,000. By adding a cement admixture consisting of a water-insoluble metal complex with an ugliness of 1 to 20μ and a water-soluble polymer having a hydroxyl group to the cement mixture, the fluidity of the cement mixture can be maintained for a long time, and the cement mixture can be improved. This led to the completion of the present invention by discovering scales that improve the workability and ease of construction.

That is, the present invention is directed to particles having a carboxyl group in the molecule, a molecular weight of 500 to 50,000, and an average particle size of 0.1 to 20μ.
A water-insoluble metal complex having an average particle size of 0.1 to 20 μm, consisting of a water-insoluble polymer (A,) which is I, and/or a polymer with a molecular weight of 500 to 50,000 having a carboxyl group in the molecule, and a divalent metal. (A2) and the water-soluble polymer (B) having a hydroxyl group are added in an amount of 0.1 to 2 parts by weight of component (B) per 1 part by weight of component (A1) and/or component (A2).
This invention relates to a cement admixture characterized by containing 0 parts by weight, and the cement admixture of the present invention is an extremely effective cement admixture for preventing a decrease in fluidity of a cement mixture.

The mechanism of fluidity reduction according to the present invention is presumed to be as follows.

Cement, water and if necessary sand, gravel, admixtures (agents)
The cement particles in the cement mixture formed by mixing
After kneading, chemical aggregation due to hydration reaction and physical aggregation due to interparticle attraction progress, and fluidity is gradually lost. For this reason, slump loss occurs in cement mixtures such as concrete and mortar. By adding a cement dispersant at this point, a repulsive force is generated between the cement particles, the cement particles are dispersed, and fluidity is improved, so that slump loss can be temporarily prevented.

However, the hydration reaction of cement progresses further, and a gel of ettringite (commonly known as cementobacillus or calcium sulfoaluminate) is continuously produced. For this reason, the fluidity of the system continues to decrease, and the cement dispersant is adsorbed or stored in the solution, cement particles, and new precipitated minerals such as ettringite newly formed in L, and the concentration of the cement dispersant in the solution decreases. , aggregation of cement particles progresses.

If the amount of dispersant stored on the surface of the cement particles is minimized and if the cement dispersant can be continuously supplied by some method, the decrease in fluidity can be more effectively prevented.

The present inventors have already developed an olefin and maleic anhydride copolymer (
(Japanese Patent Publication No. 63-5346) and its metal complex (Japanese Patent Publication No. 62-83344); They discovered that by using these molecules in combination, the slump loss prevention effect is dramatically improved compared to when each composition is used alone, leading to the completion of the present invention.

Water-insoluble polymers (A + ) and/or water-insoluble metal complexes (A2) such as olefin and maleic anhydride copolymers and their metal complexes continuously supply dispersant components in concrete to prevent slump loss. However, due to the hydration reaction of cement, a large amount of dispersant components are stored, and the amount of dispersant components that work effectively is reduced, so although sufficient slump loss prevention effects have been achieved. do not have.

Therefore, in the present invention, due to the combined effect of the water-soluble polymer (B) having hydroxyl groups, water-insoluble polymers (8) such as olefin and maleic anhydride copolymers and their metal complexes (8) and/or water-insoluble metal complexes (8) The slump loss prevention effect of A2) has been dramatically improved. This is because the water-soluble polymer (B) forms a weak colloidal adsorption film on the surface of cement particles in cement formulations, especially on the surface of the highly active aluminate phase, which has a significant storage capacity for dispersants and forms ettringite gel. However, it is presumed that this is because the dispersant component supplied into the system over time was able to contribute to adsorption and dispersion more efficiently in order to prevent it from being stored in the ettringite gel.

Hereinafter, the contents of the present invention will be explained in detail.

Used in the present invention has a carboxyl group in the molecule, has a molecular weight of 500 to 50,000, and has an average particle size of 0.1 to 20
The water-insoluble polymer (A,) having a carbon number of 2 μm is
Examples include copolymers whose main components are olefins of 8 to 8 and ethylenically unsaturated dicarboxylic acid anhydrides, and naturally there are also copolymers containing hydrophobic and vinyl-based hydrophilic monomer components that can be copolymerized with these. included.

Examples of olefins having 2 to 8 carbon atoms include ethylene,
Propylene, n-butene, isobutylene (return B,
B), n-pentene, cyclopentene, 2-methyl-1-butene, n-hexene, cyclohexene, 2-
Examples include methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-butene, diisobutylene, and mixtures thereof, with isobutylene being particularly preferred. Examples of the dicarboxylic anhydride include maleic anhydride, itaconic anhydride, citraconic anhydride, and the like, with maleic anhydride being preferred.

On the other hand, as the polymer having a carboxyl group in the molecule and having a molecular weight of 500 to 50,000 and forming the divalent metal and water-insoluble metal complex (A2) of the present invention, acrylic acid, methacrylic acid, which has excellent cement dispersibility, Homopolymers or copolymers with copolymerizable heptamers, homopolymers of maleic acid (anhydride), itaconic acid, fumaric acid or copolymers with copolymerizable monomers, etc. In particular, a copolymer of an olefin having 2 to 8 carbon atoms and an ethylenically unsaturated dicarboxylic acid anhydride or a (meth)acrylic acid copolymer having a molecular weight of 500 to 50,000 are preferred.

Specifically, the compounds shown below can be mentioned.

Homopolymers of (meth)acrylic acid Copolymers of (meth)acrylic acid and (meth)acrylic acid esters Copolymers of (meth)acrylic acid and acid amides and their esters, copolymers of (meth)acrylic acid and other copolymers Copolymers with possible hydrophilic monomers (e.g. allyl alcohol) (meth)acrylic acid and copolymerizable hydrophobic monomers (
copolymers of (meth)acrylic acid and α,β-unsaturated dicarboxylic acids (e.g. maleic acid, itaconic acid); copolymers of α,β-unsaturated dicarboxylic acids and (meth)acrylic esters ,α,
Homopolymers of β-unsaturated dicarboxylic acids, copolymers of α,β-unsaturated dicarboxylic acids and alkenes having 2 to 8 carbon atoms, hydrophobic monomers copolymerizable with α,β-unsaturated dicarboxylic acids (e.g. styrene) copolymers with α,β−
Copolymers of unsaturated dicarboxylic acids and other copolymerizable hydrophilic monomers, copolymers of α,β-unsaturated dicarboxylic acids and acid amides, and esters thereof; Among these, olefins having 2 to 8 carbon atoms ( alkenes) and ethylenically unsaturated dicarboxylic acids (α
, β-unsaturated dicarboxylic acid) is preferred.

If the hydrophobic ratio increases, steric hindrance increases and the metal complex becomes unstable, so proper hydrophilic/
Hydrophobic balance is required. In addition, the molecular weight is 500~
5oooo is desirable. If the molecular weight is too large than this range, the intermolecular crosslinking force will be large, and if it is too small, it will be too small, and neither of these will affect the dispersibility, making it unsuitable. A more preferable molecular weight range is 2000~
It is 20,000.

The optimum average particle size is 0.1 to 20 μm, and 0.1 μm
If it is less than 20 μm, the dissolution rate will be too fast, and if it exceeds 20 μm, the dissolution rate will be slow and there is a risk that it will be localized in the cement mixture.

The water-insoluble metal complex (A2) in the present invention is composed of a carboxyl group of a polymer and a divalent metal or a divalent metal compound, has a physical or chemical bond, and has a solubility in water of 8 g/100 d. A metal complex is shown below.

Examples of divalent metal ions constituting the metal complex include Ca, Cur Ni+ Zn+ Fe, M
g+ Co.

Examples include one or a mixture of two or more metal ions such as Ba, with Zn, Cu, and Fe being particularly preferred.

The water-soluble polymer (B) having a hydroxyl group in the present invention includes soluble starch, polyethylene glycol/L/(PEG
), polyvinyl-yl+-/l/(PVA), human t'roxymethyl(ethyl)cellulose (IIMC, H
Examples include water-soluble polymers having hydroxyl groups in the molecule, such as EC), methylcellulose (MC), water-soluble rubber and gum. Particularly preferred among these are water-soluble starches having an average molecular weight of 2.5 to 3 million and easily soluble in water, including α-starch, starch paste, dextrin, heat-treated starch, oxidized starch, oligosaccharide, etc. . If the average molecular weight of the water-soluble starch is less than 250, the curing delay will be large and the physical properties of the hardened cement composition will be adversely affected, while if it exceeds 3 million, water solubility will disappear and the effects of the present invention will not be found.

The amount of water-soluble polymer (B) in the cement admixture of the present invention is 0.1 to 20 parts by weight per 1 part by weight of water-insoluble polymer (A1) and/or water-insoluble metal complex (A2). If the amount exceeds 20 parts by weight, the curing retardation effect becomes significant and adversely affects the physical properties of the cured product of the cement mixture. On the other hand, if it is less than 0.1 part by weight, a sufficient adsorption film cannot be formed.

The cement admixture of the present invention is 0.00% compared to normal cement.
It is mixed in an amount of about 1 to 0.2% by weight.

In addition, the cement admixture of the present invention may be a conventional cement dispersant, such as a naphthalene sulfonic acid formaldehyde high condensate water reducing agent such as a β-naphthalene sulfonic acid formaldehyde high condensate or its salt, or a water-soluble salt of a sulfonated melamine resin. sulfonated melamine resin water reducing agents such as sulfonated melamine resin water reducing agents, lignin sulfonic acid water reducing agents such as lignin sulfonic acid or its salts, or water-soluble salts of copolymers of olefins having 2 to 8 carbon atoms and ethylenically unsaturated dicarboxylic acids, It is preferable to use one or more dispersants selected from (meth)acrylic acid polymers and maleic acid polymers. The dispersant used in this case is 0.0
It is added in an amount of about 1 to 2% by weight.

The cement admixture according to the present invention can be added to a cement mixture in the form of a suspension, powder, or granules. Addition to worked cement formulations is also possible. In addition, when using a cement dispersant together,
An admixture consisting of a water-insoluble polymer (A) and/or a water-insoluble metal complex (A2) and a water-soluble polymer (B) and a cement dispersant may be mixed in advance,
Alternatively, one may be blended into cement or a cement mixture, or one may be blended into cement or a cement blend and kneaded before the other is blended.

Also, other cement additives (materials), such as air entraining agents,
Glidants, waterproofing agents, swelling agents (materials), graph fibers,
It is also possible to use it in combination with steel fiber, fly ash, blast furnace slag, etc.

Concrete containing the cement admixture according to the present invention can be hardened by a conventional method of curing concrete, and can also be hardened by methods such as steam curing and autoclave curing.

The effects of the admixture of the present invention are as follows.

(1) Suppress concrete slump loss or mortar flow decline.

(2) When constructing cast-in-place mortar or concrete, it is no longer necessary to add a water-reducing agent or a superplasticizer to recover from slump.

(3) At concrete product factories, slump losses were assumed to be larger than necessary, but this will no longer be necessary.

(4) It becomes easier to manage concrete and mortar.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Based on the formulation shown in Table-1, 100! Using a tilting mixer, 50! of concrete material and the specified cement admixture shown in Table 2 were added, mixed at high speed for 2 minutes, and then mixed for 4 r.
Concrete tests were conducted by measuring slump at predetermined times while agitating at a constant rate of pm.

The results are shown in Table-3.

Plate - Nen Table-1 Cement admixtures are listed below. It was added in the amount shown in 2.

"Kyo" ■ Fine aggregate (S): Ki's usage (specific gravity 2.57) Coarse aggregate (G)
: Hidaka use (specific gravity 2.61) water (-) Chumu 2, coarse water-insoluble polymer (8), isobutylene and maleic anhydride (molar ratio 1:1) copolymer, water-insoluble metal A copper, zinc, and iron complex of isobutylene and maleic anhydride (molar ratio 1:1) copolymer was used as the complex (A2), an oligosaccharide with a molecular weight of 3000 was used as the water-soluble polymer, and various cement admixtures shown in Table 2 were used. was prepared. The particle size of the copolymer was adjusted by pulverizing the coarse polymer slurry in a sand mill (manufactured by Igarashi Kikai) for a predetermined period of time.

Note) *1: Weight % to cement *2: Oligosaccharide/copolymer or copolymer metal complex weight ratio Wheel 3: Average particle size of copolymer or copolymer metal complex *4: Copolymer or copolymer metal complex weight ratio Average molecular weight of copolymer metal complex *5: Molecule! t3000 oligosaccharide *6: isobutylene and maleic anhydride (molar ratio 1:1)
Copolymer *7: Isobutylene and maleic anhydride (molar ratio 1:1)
Copolymer zinc complex *8 Diisobutylene and maleic anhydride (molar ratio 1:1) Copolymer copper complex Book 9: Isobutylene and maleic anhydride (molar ratio 1:1)
As is clear from the above results showing the delay time from the copolymer iron complex concrete test results, oligosaccharide alone (Nα2)
It can be confirmed that the product of the present invention can significantly improve the slump loss of concrete compared to the copolymer alone (Nα3 to 6).

Also, No. in which the molecular weight or average particle size of the copolymer and its metal complex is outside the scope of the present invention.

Nos. 11 to 14 do not provide a sufficient slump loss prevention effect.

In addition, Nα15, No. 17, which have a low oligosaccharide blending ratio
On the other hand, when the blending ratio of oligosaccharide is too high, concrete curing delay is too large in samples No. 16, No. 18, and the concrete cannot be used.

Example 2 A concrete test was conducted in the same manner as in Example 1 using the cement admixtures shown in Table 4 in the amounts shown in Table 4.

The results are shown in Table-5.

Note that the average particle diameter of the water-insoluble polymer and water-insoluble metal complex used in this example is 0.6 to 0.8 μm.

A surface admixture was prepared and a concrete test was conducted in the same manner as in Example 1.

The results are shown in Table-6.

(a) β-naphthalenesulfonic acid formaldehyde high condensate, etc.) Water-soluble salt of sulfonated melamine resin (C) Lignosulfonic acid (d) 50 parts by weight of β-naphthalenesulfonic acid formaldehyde high condensate and 50 parts by weight of geninsulfonic acid Mixture of β-naphthalenesulfonic acid formaldehyde high condensate 5
Mixture (e) of 0 parts by weight and 50 parts by weight of polyacrylic acid Example 3 As the water-insoluble polymer (A1), isobutylene/maleic anhydride (mole ratio 1:1) copolymer (molecular weight 10,000, average particle size 0 .8 μm), molecular weight i3 as water-soluble polymer (B)
000 oligosaccharide in combination with the cement dispersants (a) to (e) shown below. [Effect of the invention] From the examples, it is clear that the Insoluble metal complex (A2) and water-soluble polymer (B)
It is clear that the slump retention effect of the product of the present invention in which both are used together is significantly improved compared to when each is used alone.

Since the present invention makes it possible to increase the fluidity of concrete and keep the fluidity constant, the cement admixture according to the present invention can be used for various purposes. For example, if it is used as a concrete pumping aid, it is possible to prevent a sudden increase in pumping pressure when pumping is resumed due to interruptions in working hours, pump failure, etc. In addition, when used as a centrifugal compaction aid, the fluidity of concrete 1 can be maintained for a long time before molding, making it easier to finish the product.

Further, as other examples, cement milk or mortar grouting aid, cement I-
It is also effective for maintaining fluidity and preventing material separation in compounds, underwater concrete, concrete for continuous underground walls, etc.

Claims (1)

[Claims] 1. Molecular weight 500-5 having a carboxyl group in the molecule
0,000 and an average particle size of 0.1 to 20 μm (A_1), and/or a polymer with a molecular weight of 500 to 50,000 having a carboxyl group in the molecule and a divalent metal with an average particle size of 0 A water-insoluble metal complex (A_2) having a diameter of 1 to 20 μm and a water-soluble polymer (B) having a hydroxyl group are combined with the component (A_1) and/or (A
_2) A cement admixture characterized by containing component (B) in a ratio of 0.1 to 20 parts by weight per 1 part by weight of component. 2. The cement admixture according to claim 1, wherein the water-soluble polymer (B) having a hydroxyl group is a water-soluble starch. 3. A water-soluble naphthalenesulfonic acid formaldehyde high condensate system containing the water-insoluble polymer (A_1) and/or the water-insoluble metal complex (A_2) according to claim 1 and a water-soluble polymer (B), and which is further water-soluble Water reducing agent, sulfonated melamine resin water reducing agent, lignin sulfonic acid water reducing agent, (
A cement admixture containing one or more dispersants selected from meth)acrylic acid polymers and maleic acid polymers.