JPH1081550A - Cement admixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement admixture consisting of a compound having specific molecular structure, excellent in cement dispersion effect and slump retention without exhibiting cement hardening retardancy, and also having significant material segregation resistance. SOLUTION: This cement admixture consists of a formaldehyde co-condensate mode from (A) polyasparagine (salt))(pref. of the formula (X is an alkali metal, alkaline earth metal, ammonium, amino, etc.; (n) is an integer of 3-300), (B) a monomer capable of formaldehyde co-condensation with the component A (pref. melamine or derivative therefrom. phenol or derivative therefrom), and (C) a compound capable of forming sulfo group (pref. sodium sulfite, sodium bisulfate, etc.).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a cement admixture. More specifically, cement paste,
The present invention relates to a cement admixture which is added when kneading a hydraulic cement composition such as mortar and concrete to improve the workability.

[0002]

2. Description of the Related Art
Various types of organic compounds added to cement, particularly as a cement water reducing agent, are known. Representative examples are salts of highly condensed β-naphthalene sulfonic acid formaldehyde, salts of melamine sulfonic acid formaldehyde condensate, lignin sulfonic acid salts, salts of amino sulfonic acid condensate, and oxycarboxylic acids. . When these compounds are added to a kneaded product composed of cement, water and aggregate, sufficient workability can be obtained even if the amount of water during kneading is reduced. Therefore, there is an advantage that workability is improved, and since the water-cement ratio can be reduced, it is useful for enhancing the strength of a hydraulic cement composition such as cement paste, mortar, and concrete.

[0003] However, in general, cement paste,
Mortar, hydraulic cement composition such as concrete,
With the passage of time after kneading, the fluidity is lost. This phenomenon occurs when the organic compound added as the cement water reducing agent is used, and particularly, β-
The use of a salt of a highly condensed naphthalene sulfonate formaldehyde or the like is remarkable, and depending on the composition of concrete, a phenomenon in which the slump is reduced to half or less within 30 minutes after kneading is observed. Due to the phenomenon that the slump loss is large, the following problems occur. In other words, the concrete composition may be pumped by pumping concrete, but if the pumping is temporarily interrupted due to a break time or various troubles at that time, the pumping pressure may suddenly increase when resuming, And piping may be blocked. Also, due to reduced fluidity, the compact may not be sufficiently compacted in the mold and a defective portion may be generated.

Therefore, various water reducing agents have been developed in the past in order to suppress slump loss. For example, a substance in which the functional group is dissociated by an alkali in concrete, a so-called sustained-release high-performance water reducing agent (Japanese Patent Publication No. 63-5346) is known. Further, a water-soluble vinyl copolymer (Japanese Patent Publication No. 6-60042) is known, in which a new functional group appears by being hydrolyzed in an alkali and suppresses slump loss. Further, for the purpose of maintaining a slump due to steric hindrance of a molecular chain, a polyalkylene glycol monoester monomer having an unsaturated bond and a (meth) acrylic acid monomer and / or an unsaturated dicarboxylic acid monomer And copolymers thereof (JP-B-59-18338,
Japanese Patent Publication No. 2-7897, Japanese Patent Publication No. 2-7898, Japanese Patent Publication No. 2-7901, Japanese Patent Publication No. 2-8983, Japanese Patent Publication No. 2-11542, Japanese Patent Publication No. 5-110
No. 57, Japanese Patent Publication No. Hei 6-88817) and the like, and water-soluble vinyl copolymers (these are collectively referred to as polycarboxylic acid type). Furthermore, a condensate in which a polyalkylene glycol chain has been introduced into an aromatic compound (JP-A-6-340559) has recently been developed.

[0005] However, while these compounds exhibit excellent flow effects, they have various problems. First,
In the case of sustained-release high-performance water reducing agents that work with alkali in concrete and water-soluble vinyl copolymers that are alkali-hydrolyzed to replenish functional groups and suppress slump loss, carboxyl groups are contained in the compound. Appears over time. This carboxyl group has a large bonding force with calcium ions. Therefore, these compounds have a problem in that they capture calcium ions in the cement and increase the setting delay.

The polycarboxylic acid having an oxyalkylene chain in the molecule has high air entrainment, and it is difficult to control the amount of air in concrete. Actually, the amount of air is controlled using an antifoaming agent, but the problem is that the amount of air fluctuates greatly depending on the kneading conditions in a concrete mixer, the agitator conditions of a mixer truck, and the transport time, making it difficult to use. is there. In addition, when a large slump is used, that is, when soft mortar or concrete is used, material separation may occur, which is a problem.

Further, a condensate in which a polyalkylene glycol chain is introduced into an aromatic compound has a problem that a flow effect similar to that of a polycarboxylic acid having an oxyalkylene chain in a molecule cannot be recognized.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve these problems, and as a result, it has been found that a compound having a specific molecular structure does not exhibit air entrainment and curing retardation. Shows excellent dispersion effect and slump retention effect,
The inventors have found that they have remarkable material separation resistance, and have accomplished the present invention.

That is, the present invention comprises polyasparagine or a salt thereof (A), polyasparagine or a salt thereof (A), a monomer (B) capable of co-condensing with formaldehyde, and a compound (C) which forms a sulfone group. The present invention relates to a cement admixture which is a formaldehyde cocondensate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The polyasparagine or a salt thereof (A) used in the present invention has the general formula (I) n: represented by an integer of 3 to 300. As a synthesis method, α-poly-L-aspartic acid-β-benzyl ester is dissolved in aqueous ammonia, and the aqueous ammonia is removed, followed by extraction using alcohol and ether. And a method of dissolving poly-L-succinimide in aqueous ammonia, removing the aqueous ammonia, and extracting with alcohol or ether.
The polyasparagine used in the present invention may be produced by any method, and can be purified according to a known method if necessary.

The asparagine unit in polyasparagine may be any of D-form, L-form and DL-form. Further, the degree of polymerization n of polyasparagine is preferably from 3 to 300. If it is less than 3, the flow effect and the slump loss suppressing effect of the cement admixture are not sufficient, which is not preferable. Also, 30
If it exceeds 0, the co-condensation does not proceed sufficiently, which is not preferable.

The compound represented by the general formula (I) may be added in all the steps of the reaction process for producing the cement admixture of the present invention, but the compound represented by the following general formula (II) and / or General formula (III) and / or general formula (IV)
And / or a step after charging the compound represented by the general formula (V) is preferable.

The compound represented by the general formula (I) is 1
More than one type can be used in combination. Furthermore, the amount of the monomer is (B) which can be co-condensed with polyasparagine or its salt (A) and formaldehyde.
0.0005 to 0.3 mol is preferable to 1 mol. When the amount of the compound represented by the general formula (I) is less than 0.0005 mol, the effect of suppressing the slump loss is small, which is not preferable. On the other hand, if it exceeds 0.3 mol, it is difficult to control the reaction, and it is not preferable because it is economically disadvantageous.

As the monomer (B) capable of co-condensing polyasparagine or a salt thereof (A) with formaldehyde,
General formula (II) Melamine, melamine containing a methylol group, melamine containing a sulfomethyl group, etc. can be used. In the case of melamine containing a sulfomethyl group,
The salts can also be used. Salts include inorganic salts, i.e., alkali metal salts or alkaline earth metal salts such as potassium, sodium, and magnesium, or organic salts, i.e., ammonium salts, amine salts such as monoethanolamine salts, diethanolamine salts, and substituted amines. Salts and the like can also be used.

In addition, other than the above, general formula (III) , Or phenol, alkylphenols such as cresol, pt-butylphenol, pt-amylphenol, or their sulfonic acids or salts of sulfonic acids. As the salts, similarly to the general formula (III), inorganic salts and organic salts thereof can be used. Among them, phenol or phenolsulfonic acid and salts thereof are preferable from the viewpoint of economy and reactivity.

Further, the compound represented by the general formula (IV) , Urea, urea containing a methylol group, and urea containing a sulfomethyl group can also be used.
In the case of a sulfomethyl group-containing urea, inorganic salts and organic salts thereof can be used as in the case of the general formula (IV).

Furthermore, the general formula (V) Compounds represented by, i.e., sulfanilic acid, metanic acid, aminobenzenesulfonic acids such as ortanic acid,
Alternatively, salts thereof can be used. Above all,
Sulfanilic acid, metanic acid and salts thereof are preferred from the viewpoint of economy and reactivity.

In the present invention, general formula (II):
Formula (III), Formula (IV), and Formula (V)
One or more monomers may be used in combination, but it is preferable to use the general formula (II) from the viewpoint of economy and reactivity.

Compounds that generate a sulfone group include:
Known sulfonating agents such as sodium sulfite, sodium bisulfite, sodium pyrosulfite, sulfur dioxide, fuming sulfuric acid and the like can be used.

These sulfonating agents may be used in advance for introducing a sulfomethyl group into the raw materials corresponding to the general formulas (II), (III) and (IV), or may be used for co-condensation with formaldehyde. The sulfomethyl group may be introduced directly into the co-condensate by acting after synthesizing the isomer.

The sulfomethyl group can be introduced into melamine by a known method. That is, the compound can be introduced by addition condensation of melamine with formaldehyde to obtain methylol melamine, followed by a sulfonating agent and replacement with a hydroxyl group. It is known that 6 mol of formaldehyde is addition-condensed as methylol group to 1 mol of melamine. In the present invention, since it is highly possible that 2 moles of methylol groups are used for cocondensation, sulfomethyl groups can be introduced into the remaining 4 moles of methylol groups at the maximum. In consideration of the economical aspect and the flow effect of the obtained co-condensate, the amount of sulfomethyl group introduced is preferably 0.3 to 4 mol,
The introduction of 5 to 2 mol is more preferred. The same applies to the case where a sulfomethyl group is introduced into urea. The amount of introduction is preferably from 0.3 to 2 mol, more preferably from 0.5 to 1.5 mol per mol of urea.

The formaldehyde used for synthesizing these formaldehyde cocondensates is usually 3
Those having a concentration of 0 to 60% by weight can be used. Further, if necessary, paraform can be used in combination. The amount of formaldehyde used is preferably 1 to 6 times the total number of moles of polyasparagine (A) and the total number of monomers (B) capable of formaldehyde cocondensation. In consideration of economy, ease of the condensation reaction, and the like, it is more preferable to use 1.5 to 4 moles.

The formaldehyde co-condensation reaction is carried out at pH 4-1.
The method is carried out by a usual method in the range of 2, ie, from a weakly acidic region to a basic region. When the pH is 4 or less, it is difficult to control the reaction, for example, the condensation reaction may rapidly proceed and gel. In addition, the formaldehyde may be added in advance in a reaction apparatus, or may be added dropwise to formalin for the reaction.

The composition of the compound constituting the cement admixture in the present invention is important. That is, the molar ratio of polyasparagine or a salt thereof (A): polyasparagine or a salt thereof (A) and a monomer capable of co-condensing with formaldehyde (B): a compound generating a sulfone group (C): 0.0005-0.3):
1: (0.3 to 4): (1 to 6) is preferable. More preferably (0.005 to 0.1): 1:
(0.5-2): (1.5-4) is preferred.

Next, an example of a specific method for producing the cement admixture according to the present invention will be described below, but the present invention is not limited thereto. Example 1 Formaldehyde and water were mixed with a stirrer, a thermometer, a reflux tube and a dropping funnel.
Monomer (B) that can be charged in a one-necked flask and co-condensed with polyasparagine or its salt (A) and formaldehyde
Is added. Reactor internal temperature 60-90
After raising the temperature to 0 ° C, the reaction is carried out under basic conditions for 0.5 to 2 hours. Next, a compound represented by polyasparagine or a salt thereof (A) is charged, and the mixture is further added at 60 to 90 ° C for 0.5 to 2 hours.
Let react for hours, then cool to 30-50 ° C. further,
The compound (C) which forms a sulfone group is added, and
React at 90 ° C. for 0.5 to 3 hours. Further, the inside of the system is made weakly acidic, and the reaction proceeds at 50 to 80 ° C. until the viscosity of the solution reaches a predetermined value. When the viscosity of the solution reaches a predetermined value, the reaction is stopped by neutralization. The predetermined viscosity at which the reaction is stopped varies depending on the nonvolatile content of the solution.
0 cp / 25 ° C. is preferable, and 15 to 300 cp / 25 ° C.
Is more preferred. When the viscosity is out of this range, even if the obtained co-condensate is added to the cement composition, the flow effect and the slump loss suppressing effect may not be sufficiently exhibited.

This polyasparagine or a salt thereof (A)
Can be added in all the steps of the reaction process for producing the cement admixture of the present invention, but a monomer (B) capable of co-condensing polyasparagine or a salt thereof (A) with formaldehyde It is preferable to add the compound represented by the following formula to the step after charging. That is, polyasparagine or a salt thereof (A) and a compound represented by a monomer (B) capable of formaldehyde cocondensation may be added to add a compound represented by the following formula. Thereafter, the compound may be added before or after the preparation of the compound (C) that generates a sulfone group, or may be added immediately before or immediately after adjusting the pH to a weakly acidic region. Further, for the purpose of cooling, the charged water may be divided into the respective steps, or the addition of each compound may be divided and added. Further, the order of adding each compound may be changed.

The cement admixture of the present invention can be used in combination with other conventionally known water reducing agents, AE water reducing agents, high performance water reducing agents, and high performance AE water reducing agents. That is, β-naphthalenesulfonic acid formaldehyde high condensate salt,
Combined use with salts of melamine sulfonic acid formaldehyde condensate, amino sulfonic acid condensate, lignin sulfonate, oxycarboxylic acid, polycarboxylic acid type water reducer, alkali hydrolysis type water reducer, sustained release type high performance water reducer, etc. can do.

As to the method of using the admixture of the present invention, other known cement admixtures such as an air entrainer, an antifoaming agent, a setting accelerator, a setting retarder, a rust inhibitor, a preservative, a waterproofing agent, and a strength promoter It can be used in combination with an agent or the like. In addition, the method of use is usually mixed in kneading water and added to the cement composition.However, the method of adding the cement composition at once or adding it separately at the time of preparing the cement composition, the method of adding the cement composition after kneading, Any method such as the method of adding may be used. The admixture according to the present invention varies depending on the formulation and the use of the cement composition, but is usually 0.01 to 0.01 in terms of solid content relative to cement.
It is used in a proportion of 2.0% by weight, preferably 0.05 to 1.0% by weight. If the amount is too small, the dispersion fluidity tends to decrease, and the effect of preventing slump loss tends to decrease. Conversely, if the amount is too large, it tends to cause material separation, making it difficult to obtain a homogeneous cured product, and is disadvantageous economically, which is not preferable.

The cement admixture according to the present invention can be applied to concrete and mortar prepared using various portland cements, fly ash cements, blast furnace cements, silica cements, various types of mixed cements and the like.

The reason why the cement admixture of the present invention exhibits excellent flow effect, slump loss suppressing effect and material separation resistance is not clear, but is presumed as follows. That is, the cement admixture of the present invention enhances the dispersibility of the cement particles by the electric repulsion of the sulfone group in the molecule. When the admixture of the present invention is adsorbed on the cement particles, it is considered that the asparagine side chain in the molecule extends to the outside of the cement particles. A hydration layer is formed around the polyasparagine side chains extending outward, and the steric hindrance accompanying the hydration layer is expected to maintain the dispersibility of the cement particles for a long time and suppress slump loss. Further, unlike a polycarboxylic acid-based water reducing agent, since it does not have a carboxyl group or an oxyalkylene group in the molecule, it is not expected to exhibit a setting retardation property and an air entrainment property. Therefore, the admixture of the present invention has excellent dispersion performance, slump loss suppressing effect, and material separation resistance.

The admixture of the present invention will be described in more detail in the following examples, but the present invention is not limited thereto. In addition, all percentages or parts described below as units of numerical values are% by weight or parts by weight unless otherwise specified.

[0032]

【Example】

Synthesis of polyasparagine 0.5 g of poly-L-succinimide was dissolved in 5 ml of 28% aqueous ammonia and allowed to stand at room temperature overnight, and then the aqueous ammonia was distilled off under reduced pressure. The residue was extracted with alcohol and ether and dried to obtain polyasparagine. Poly used
By changing the molecular weight of L-succinimide, several types having different molecular weights (polymerization degree n: 15, 42, 98, and expressed as weight average molecular weight: 1800, 49, respectively)
00, 11500).

Production Example 1 0.52 mol (65.5 parts) of melamine, 3.0 mol (243.2 parts) of 37% formalin and 250.0 parts of water were added to a stirrer, thermometer, reflux tube and dropping funnel. The mixture was charged into a four-necked flask and mixed with stirring. After the temperature was raised to 65 ° C., the pH was adjusted to 11.5 with a 25% aqueous sodium hydroxide solution.
The reaction was performed at 65 ° C. for 1 hour. Add 0.2 mole of urea (1
2.0 parts) and 0.15 mol of sulfanic acid (26.0).
Was added and the mixture was further reacted at 70 ° C. for 1 hour. Next, 209.0 parts of water was added, and the mixture was cooled to 45 ° C. at the same time. Then, 0.13 mol (15.2 parts) of phenol was added thereto over 30 minutes using a dropping funnel. After completion of the charging, the reaction was carried out at 60 ° C. for 1 hour. Subsequently, polyasparagine synthesized by the method described above (degree of polymerization n: 98, weight average molecular weight 1)
1500) in 0.03 mol (345.0 parts), water 38
1.0 part, anhydrous sodium bisulfite 0.53 mol (5
5.1 parts) and reacted at 80 ° C. for 1 hour. 60
After cooling to 40 ° C., the pH was adjusted to 6.0 with 40% sulfuric acid,
C., and the reaction was performed.
When the temperature reached 5 ° C., the reaction was stopped by neutralization with a 25% aqueous sodium hydroxide solution. The composition and physical properties are shown in Table 1.

Production Example 2 647.8 parts of water, 3.1 mol of 37% formalin (25 mol
(1.4 parts) was charged into a four-necked flask equipped with a stirrer, a thermometer, and a reflux tube, followed by stirring and mixing. 0.7 mol (88.2 parts) of melamine and 0.1 mol of urea (6.
0 parts), 0.2 mol (34.6 parts) of sulfanilic acid and 0.5 mol (95.0 parts) of sodium pyrosulfite were added with stirring. This was heated to 75 ° C., and after confirming that it had become a transparent liquid, polyasparagine synthesized by the method described above (polymerization degree n: 98, weight average molecular weight 1)
1500) after adding 0.013 mol (149.5 parts),
PH 11 with 25% aqueous sodium hydroxide solution, 75 ° C
For 2 hours. After confirming that free sulfite ions had disappeared, the mixture was cooled to 60 ° C. Then 40%
The pH was adjusted to 6.0 with sulfuric acid, and the reaction was allowed to proceed at 60 ° C. When the viscosity of the reaction solution reached 120 cp / 25 ° C, the reaction was stopped by neutralizing with a 25% aqueous sodium hydroxide solution, and the resulting product was obtained. Was designated as condensate 2. The composition and physical properties are shown in Table 1.

Production Example 3 470.0 parts of water, 2.8 mol of 37% formalin (22 mol
7.0 parts) was charged into a four-necked flask equipped with a stirrer, a thermometer, and a reflux tube, followed by stirring and mixing. 1.0 mol (126.0 parts) of melamine is added to the flask with stirring.
After heating this to 70 ° C. and confirming that it became a transparent liquid, 0.004 mol of polyasparagine (polymerization degree n: 98, weight average molecular weight 11500) synthesized by the method described above (46. 0 parts) The pH was adjusted to 11 with a 25% aqueous sodium hydroxide solution, and the mixture was reacted at 70 ° C for 1 hour. Then cool to 55 ° C and dry sodium bisulfite 0.8
(83.2 parts) was added. Although the internal temperature increased by the addition of anhydrous sodium bisulfite, the temperature was further increased to 80 ° C. The reaction was continued at 80 ° C., and after confirming that free sulfite ions had disappeared, the mixture was cooled to 60 ° C. Next, the pH was adjusted to 6.0 with 40% sulfuric acid, and the reaction was allowed to proceed at 60 ° C.
The reaction is stopped by neutralizing with
The obtained product was designated as condensate 3. The composition and physical properties are shown in Table 1.

Production Examples 4 and 5 Condensation was attempted in the same manner as in Production Example 1, except that the composition of the compound was changed as shown in Table 1. As a result, condensates 4 to 5 were obtained.

Preparation Examples 6 and 7 Condensation was attempted in the same manner as in Preparation Example 2 except that the composition of the compound was changed as shown in Table 1. As a result, condensates 6 to 7 were obtained.

Preparation Examples 8 to 9 Condensation was attempted in the same manner as in Preparation Example 3, except that the composition of the compound was changed as shown in Table 1. As a result, condensates 8 to 9 were obtained.

Production Example 10 Condensation was attempted in the same manner as in Production Example 1 except that the composition of the compound was changed as shown in Table 1. As a result, a condensate 10 was obtained.

Production Example 11 Condensation was attempted in the same manner as in Production Example 1, except that the composition of the compound was changed as shown in Table 1. As a result, a condensate 11 was obtained.

Production Example 12 Condensation was attempted in the same manner as in Production Example 2 except that the composition of the compound was changed as shown in Table 1. As a result, a condensate 12 was obtained.

[0042]

[Table 1]

[0043]

【Example】

Example 1 Using a 50-liter forced biaxial concrete mixer, cement, coarse aggregate, and condensate 1 obtained in Production Example 1 were mixed so as to obtain a kneading amount of 40 liters based on the composition shown in Table 2. Water was charged, kneading and mixing were performed for 90 seconds, coarse aggregate was further charged, and kneading was performed for 3 minutes. A highly fluid concrete having a slump of 18 cm and an air volume of 3% was prepared. In order to reach the target air volume, if the entrained air volume is insufficient, use the air entrainer Vinsol manufactured by Yamamune Chemical Co., Ltd.
When the amount of air was too high, it was adjusted using Derekrite 850 manufactured by Hokukon Sangyo Co., Ltd. as an antifoaming agent. After kneading, slump and slump flow with time were measured every 30 minutes until 90 minutes later. The compression strength is φ1
A cylindrical test specimen of 0 cm × 20 cm in height was prepared, and for one day,
It was measured on days 7 and 28. Regarding the material separation resistance, the degree of movement of the aggregate during slump flow measurement was visually observed, and relative evaluations of ◎, 、, Δ, and × were made. still,
Slump, air volume, setting time and compressive strength measurement method,
In addition, the method of preparing the specimen for compressive strength was all based on Japanese Industrial Standards (JIS-A6204). Table 3 shows the results.

[0044]

[Table 2] W / C: water / cement (% by weight) s / a: fine aggregate / (fine aggregate + coarse aggregate) (volume%) C: cement S: fine aggregate G: coarse aggregate

Material for Concrete Kneading Cement: Three kinds of ordinary Portland cement (Mitsubishi Materials Corporation, Chichibu Onoda Co., Ltd., Tokuyama Corporation) Specific gravity = 3.16 Fine aggregate: Irino from Kawachi-cho, Kamo-gun, Hiroshima Prefecture Weathered granite mountain sand Specific gravity = 2.57 Coarse aggregate: Hard sandstone crushed stone from Oishi-Ishihara-shaped wall stone in Shimonoseki-shi, Yamaguchi Crushed stone 5: Crushed stone 6 = 1: 1 Specific gravity = 2.69

Examples 2 to 9 The same operation as in Example 1 was carried out except that condensates 2 to 9 were used. Table 3 shows the results.

Comparative Examples 1 to 3 The same operation as in Example 1 was performed except that condensates 10 to 12 were used. Table 3 shows the results.

Comparative Examples 4 to 8 As a comparative water reducing agent, a commercially available high-performance water reducing agent, Melflow 40 (Mitsui Toatsu Chemical Co., Ltd .: melamine type),
Mighty 150 (Kao Corporation: naphthalene type), Palic FP200U (Fujisawa Pharmaceutical Co., Ltd .: aminosulfonic acid type), sustained release type Mighty 2000WH which is a high performance AE water reducing agent (Kao Corporation: naphthalene type + The same operation as in Example 1 was performed using Tupole HP-8 (Takemoto Oil & Fats Co., Ltd .: polycarboxylic acid system). Table 3 shows the results.

[0049]

[Table 3]

[0050]

As is clear from the examples and comparative examples, the cement admixture obtained according to the present invention shows a high flow effect at a low addition amount and a residual flow as compared with the existing cement water reducing agent. It has the characteristics of high rate and excellent daily strength. That is, it has high initial fluidity and excellent slump holding properties without causing hardening delay for cement compositions such as mortar and concrete. Furthermore, it has excellent material separation resistance. Therefore, when the cement admixture obtained by the present invention is used for civil engineering and construction-related works, workability can be significantly improved.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Naokazu Hatsuharu 7-1-1, Hikoshimasako-cho, Shimonoseki-shi, Yamaguchi Pref.

Claims (12)

[Claims] 1. Polyasparagine or a salt thereof (A)
A formaldehyde co-condensate comprising a monomer (B) capable of formaldehyde co-condensation with polyasparagine or a salt thereof (A) and a compound (C) capable of forming a sulfone group. 2. Polyasparagine or a salt thereof (A)
Is a compound represented by the following general formula (I). General formula (I) Here, X: alkali metal, alkaline earth metal, ammonium, amine, substituted amine Polymerization degree n: integer of 3 to 300 3. Polyasparagine or a salt thereof (A)
And monomer (B) capable of formaldehyde cocondensation with melamine or a derivative thereof, phenol or a derivative thereof,
The cement admixture according to claim 1, wherein the cement admixture is one or more compounds selected from the group consisting of urea or a derivative thereof, aminobenzenesulfonic acid or a derivative thereof, and alkylbenzenesulfonic acid or a derivative thereof. 4. A compound (C) which forms a sulfone group
The cement admixture according to claim 1, wherein the admixture comprises one or more compounds selected from the group consisting of sodium sulfite, sodium bisulfite, sodium pyrosulfite, fuming sulfuric acid, and sulfur dioxide. 5. The cement admixture according to claim 3, wherein the melamine or a derivative thereof is represented by the following general formula (II). General formula (II) Here, X ₁ , X ₂ , X ₃ : H, CH ₂ OH or CH
₂ SO ₃ Y Y: alkali metal, alkaline earth metal, ammonium,
Amine, substituted amine 6. The cement admixture according to claim 3, wherein the phenol or a derivative thereof is represented by the following general formula (III). General formula (III) Here, X ₄ : H, CH ₂ OH or CH ₂ SO ₃ Y,
Sulfone group or its alkali metal salt, alkaline earth metal salt, ammonium salt, amine salt, substituted amine salt Y: alkali metal, alkaline earth metal, ammonium,
Amine, substituted amine R ₃ : H or alkyl group having 1 to 6 carbon atoms 7. The cement admixture according to claim 3, wherein the urea or a derivative thereof is represented by the following general formula (IV). General formula (IV) Here, X ₅ , X ₆ ,: H, CH ₂ OH or CH ₂ S
O ₃ Y Y: alkali metal, alkaline earth metal, ammonium,
Amine, substituted amine 8. The cement admixture according to claim 3, wherein the aminobenzenesulfonic acid or a derivative thereof and the alkylbenzenesulfonic acid or a derivative thereof are represented by the following general formula (V). General formula (V) Here, X ₇ : H, an alkali metal, an alkaline earth metal,
Ammonium, amine, substituted amine R ₄ : H or an alkyl group having 1 to 6 carbon atoms 9. Polyasparagine or a salt thereof (A)
The cement admixture according to claim 1 or 3, wherein the monomer (B) capable of co-condensing with formaldehyde is melamine. 10. Polyasparagine or a salt thereof (A)
The cement admixture according to claim 1 or 3, wherein the monomer (B) capable of co-condensing with formaldehyde is phenol. 11. Polyasparagine or a salt thereof (A)
4. The cement admixture according to claim 1, wherein the monomer (B) capable of co-condensing with urea is urea. 12. Polyasparagine or a salt thereof (A)
4. The cement admixture according to claim 1, wherein the monomer (B) capable of co-condensing with formaldehyde is aminobenzenesulfonic acid.