JPH0672750A - Cement water reducing agent, cement composition containing the agent and its hardened material - Google Patents

Abstract

PURPOSE:To provide a cement water reducing agent with the fluidity of a cement composition hardly changed with time, improved in applicability, without the water reducing performance being deteriorated even when used in a cement composition having a small W/C value and capable of being easily produced and to furnish a cement composition excellent in applicability and suitable to a high-strength concrete. CONSTITUTION:This cement water reducing agent contains at least the following component A and component B. The solid weight ratio of the components A to B is controlled to A:B=9:1 to 5:5. The component A is the condensation product formed by the reaction of 2,2-bis(4-hydroxyphenyl)propane (a), aminobenzenesulfonic acid (b), formaldehyde (c) and an alkali (d) in an aq. medium in the molar ratio of a:b:c:d=0.9-1.1:1:2.3-2.7:0.8:1.2, and the component B is a ligninsulfonic acid contg. <=5wt.% of reducing saccharides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement water reducing agent, and more particularly to a water reducing agent capable of reducing the weight ratio of water to cement (hereinafter abbreviated as W / C), a cement composition using the same and a cement reducing agent containing the same. The present invention relates to a hardened cement product obtained by hardening the contained cement composition.

[0002]

2. Description of the Related Art Conventionally, a water reducing agent has been used in a cement composition from the viewpoint of improving various properties such as strength and durability of a hardened cement product such as mortar and concrete, and crack resistance, and it is excellent in water reduction. A high-performance water-reducing agent with little change in fluidity over time has been desired.

As such a high-performance cement water-reducing agent, the present inventors have already proposed a cement water-reducing agent consisting of a formaldehyde condensate of bisphenols and aminobenzene sulfonic acid and lignin sulfonic acid (Japanese Patent Laid-Open No. Hei 3). ─ 141142). However, when the above cement water reducing agent is used for secondary products such as high-strength concrete and concrete blocks whose W / C value is small, the amount of use of which is increasing along with the increase in the height of buildings, ,
There was a drawback that the water reduction performance was insufficient.

On the other hand, the present inventors have found that a water reducing agent comprising a formaldehyde condensate of bisphenols and aminobenzenesulfonic acid has a W / C value of 0.4 by itself.
It has been found that the water-reducing performance is good even when it is used for some concrete, and it has already been proposed (see Japanese Patent Application No. 3-53576).

However, when the above water-reducing agent is also used for super-high strength concrete having a W / C value of 0.25 or less, which is required as the super-rise of buildings increases, Not only the water-reducing performance is still insufficient, the cement composition using the water-reducing agent, the change in fluidity over time is inferior to that using the water-reducing agent containing the lignisulfonic acid, the workability and workability. It had the drawback of being inferior.

By the way, in recent years, even when used for high-strength concrete having a W / C value of 0.3 or less, a low-molecular-weight condensate is limited as a cement water-reducing agent that maintains the fluidity of the cement composition. It has been proposed to use an aromatic sulfonic acid formaldehyde condensate having a narrow molecular weight distribution by removing it by external filtration (JP-A-4-92).
No. 841), however, there is a drawback that the manufacturing process becomes complicated because the condensate as the main component needs to be subjected to ultrafiltration treatment.

[0007]

The inventors of the present invention have made extensive studies in order to solve the above-mentioned drawbacks. As a result, bisphenols, especially 2,2-bis (4-hydroxyphenyl) propane and aminobenzenesulfonic acid have been investigated. Also, a condensate obtained by reacting formaldehyde in a specific molar ratio does not require ultrafiltration because the condensate itself has a narrow molecular weight distribution, and since the molecular weight can be increased,
The water-reducing performance for a cement composition having a small W / C value is extremely good, and when a specific amount of lignin sulfonic acid having a reducing sugar content of not more than a certain amount is used in combination, the cement composition The inventors have found that the change with time in the fluidity of the is significantly improved and have reached the present invention.

Accordingly, the first object of the present invention is not only that the fluidity of the cement composition is less changed with time and the workability is good, but the water reducing performance is not deteriorated even when it is used for high strength concrete or the like. Another object is to provide a cement water reducing agent that is easy to manufacture. A second object of the present invention is to provide a cement composition which has good workability and is suitable for high strength concrete. A third object of the present invention is to provide a high-strength cement hardened product suitable for high-rise buildings.

[0009]

Means for Solving the Problems The above-mentioned various objects of the present invention are a cement water reducing agent containing at least the following components A and B, wherein the ratio of the components A and B is the solid content weight. A: B in a ratio of 9: 1 to 5: 5, a cement water reducing agent, a cement composition containing the same, and a cement hardened product obtained by hardening the cement composition containing the same. It was

The above-mentioned component A comprises 2,2-bis (4-hydroxyphenyl) propane (a), aminobenzenesulfonic acid (b), formaldehyde (c) and alkali (d) a: b: c: d. = 0.9-1.1: 1: 2.3
It is a condensate obtained by reacting under an aqueous condition at a molar ratio of ˜2.7: 0.8 to 1.2. The above-mentioned component B is ligninsulfonic acid which is ultrafiltered so that the reducing saccharide content is 5% by weight or less.

As the component a, 2,2-bis (4-hydroxyphenyl) propane, those containing isomers may be used. Examples of the aminobenzenesulfonic acid as the component b include 4-aminobenzenesulfonic acid and its isomers, as well as those having a methyl group such as 2-amino-5-methylbenzenesulfonic acid and its isomers. it can.

Formaldehyde as the component c is 30 to
It is preferable to use a 40% by weight aqueous solution. As the alkali which is the component d, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide or the like is preferable.

The molar ratio of the reaction components is a: b: c: d =
0.9-1.1: 1: 2.3-2.7: 0.8-1.2
It is preferably in the range of. The condensation reaction is carried out under aqueous conditions. The usual reaction conditions are such that the concentration of all reaction components in the aqueous solution is 20 to 30% by weight, the temperature is 80 to 90 ° C., and the reaction time is 15 to 20 hours.

The ligninsulfonic acid containing 5% by weight or less of the reducing sugar as the component B can be easily obtained by ultrafiltration of the sulfite pulp effluent. The fractionation membrane in the ultrafiltration treatment is preferably 5,000 to 100,000. In addition, the ligninsulfonic acid in the present invention also includes a salt thereof.

The components A and B prepared as described above are mixed by stirring by a known method so that the ratio of the solid content weight is in the range of A: B = 9: 1 to 5: 5. The cement water reducing agent of the present invention can be obtained. The cement water reducing agent of the present invention, even when used in a cement composition having a small W / C value used when producing high-strength concrete, unlike conventional water reducing agents, does not deteriorate in performance as a water reducing agent. It is preferably used for a cement composition having a W / C of 0.4 or less.

The amount of the cement water reducing agent used is preferably 0.1 to 2.0% by weight based on the solid content of the cement. If it is 0.1% by weight or less, the water reducing effect is not sufficient, and if it is 2.0% by weight or more, the phenomenon of cement separation occurs. The cement water reducing agent may be added at any time before or during the kneading of the cement composition.

In the cement composition containing the cement water reducing agent of the present invention, if necessary, other water reducing agent, sustained release dispersant, air entraining agent, waterproofing agent, swelling agent, silica fume or stone powder and the like. Cement additives may be used in combination as appropriate. Further, the strength of the obtained cement hardened product is extremely high and excellent. When the cement water reducing agent of the present invention is used in a cement composition having a small W / C value, the reason why the fluidity change with time is small and the water reducing performance is good is not clear, but it is as follows. Is estimated to be

That is, the condensate used as the component A is improved in water reducing performance since the molecular weight distribution does not spread even if the molecular weight increases, as compared with the conventional condensate, and at the same time, it is used as the component B in an ultra It is presumed that the treated ligninsulfonic acid having a complicated three-dimensional structure covers the cement particles incorporating the condensate as the component A, thereby maintaining the dispersibility and preventing the fluidity from changing with time. .

[0019]

EFFECTS OF THE INVENTION The cement water reducing agent of the present invention is easy to manufacture and, even when used in a cement composition having a small W / C, does not cause a change in fluidity with time or a decrease in water reducing performance. Therefore, it is extremely excellent as a cement water-reducing agent for cement composition for high-strength concrete and secondary concrete products used in high-rise buildings.

[0020]

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.
In addition, "part" which shows a compounding quantity shows a weight part.

Example 1. Preparation of Component A (Aqueous Condensate Solution) The following substances were charged into a reaction vessel in the amounts shown below. 4-Aminobenzenesulfonic acid 173.2 parts (1.0 mol) 2,2-bis (4-hydroxyphenyl) propane 228.3 parts (1.0 mol) Sodium hydroxide 44.0 parts (1.1 mol) ) 950.0 parts of water To the obtained solid-liquid turbid solution, 214.3 parts of a 35% by weight aqueous formaldehyde solution (2.5 mol of formaldehyde) was added dropwise under reflux, and then the mixture was stirred at 90 ° C for 15 hours to give A. An aqueous solution of a condensate as a component was obtained.

Preparation of B component (lignin sulfonic acid) The effluent of sulfite pulp was treated with an ultrafiltration membrane (NTU-350).
8: Nitto Denki Kogyo Co., Ltd.) was used to concentrate and purify the reducing sugar contained so that the solid content was 2.8% by weight to obtain a sodium salt of ligninsulfonic acid. The component A and the component B obtained as described above were mixed at a solid content weight ratio of 8: 2 to obtain a cement water reducing agent of the present invention.

Example 2. A cement water reducing agent of the present invention was obtained in exactly the same manner as in Example 1 except that the mixing ratio (solid content weight ratio) of the A component and the B component was changed to 6: 4.

Comparative Example 1. A cement water reducing agent was obtained in exactly the same manner as in Example 1 except that the mixing ratio (solid content weight ratio) of the A component and the B component was changed to 4: 6.

Comparative Example 2. A cement water reducing agent was obtained in exactly the same manner as in Example 1 except that the mixing ratio (solid content weight ratio) of the A component and the B component was changed to 2: 8.

Comparative Example 3. Only the component A obtained in Example 1 was used as a cement water reducing agent.

Comparative Example 4. Preparation of component A (condensate aqueous solution) Production Example 1 described in JP-A-3-141142
According to the above, the following components were charged in the reaction vessel in the amounts shown below. 4-Aminobenzenesulfonic acid 173.2 parts (1.0 mol) 2,2-bis (4-hydroxyphenyl) propane 114.2 parts (0.5 mol) 95% by weight sodium hydroxide 48.4 parts (1 To the obtained solid-liquid turbid solution, 171.4 parts (2 mol) of a 35% by weight aqueous formaldehyde solution was added dropwise under reflux, and then the mixture was stirred at 100 ° C. for 10 hours to obtain the component A. An aqueous solution of the condensate was obtained.

Component B The component B obtained in Example 1 was used. The component A and the component B obtained as described above were mixed at a solid content weight ratio of 8: 2 to obtain a cement water reducing agent.

Comparative Example 5. Only the component A obtained in Comparative Example 4 was used as a cement water reducing agent.

Comparative Example 6. Instead of 114.2 parts (0.5 mol) of 2,2-bis (4-hydroxyphenyl) propane used in Comparative Example 4, 125.2 parts (0.5 mol of 4,4′-dihydrodiphenyl sulfone) A cement water reducing agent was obtained in exactly the same manner as in Comparative Example 4 except that

Concrete Test The cement water reducing agents obtained in Examples 1 and 2 and Comparative Examples 1 to 6 were added to the concrete compositions having the mixing ratios shown in Table 1 to obtain respective concrete compositions. The amount of water reducing agent added is 20 cm when the slump value immediately after kneading the concrete.
Was adjusted so that

[0032]

[Table 1]

In the test, a forced kneading mixer having a capacity of 50 liters was used. First, the cement and the bone-removing agent were charged into the mixer and mixed, and then water containing a water reducing agent was added to the mixture.
Immediately after kneading for 0 second, then adding coarse aggregate and kneading for 2 minutes, and after 60 seconds elapsed, the slump and the air amount were measured. The results are as shown in Tables 2, 3 and 4. In addition, the slump and the air amount are JI
It measured based on S. These results show that the water reducing agent of the present invention can exhibit a sufficient water reducing effect with a small amount of addition, and demonstrate the effectiveness of the present invention.

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI technical display location C04B 24:22) D 2102-4G (72) Inventor Shinji Hamada 2-8 Iida-cho, Iwakuni-shi, Yamaguchi Prefecture -1 Sanyo Kokusaku Pulp Co., Ltd. Production Technology Laboratory

Claims (3)

[Claims] 1. A cement water reducing agent containing at least the following components A and B, wherein the ratio of the components A and B is A: B = 9: 1 to 5: 5 in terms of solid content weight ratio. A water reducing agent for cement; A component: 2,2-bis (4-hydroxyphenyl) propane (a), aminobenzenesulfonic acid (b), formaldehyde (c) and alkali (d) : B: c:
d = 0.9-1.1: 1: 2.3-2.7: 0.8-
Condensate obtained by reacting under an aqueous condition at a molar ratio in the range of 1.2; Component B: Lignin sulfonic acid containing 5% by weight or less of reducing sugar. 2. A cement composition comprising at least water, cement and the cement water reducing agent according to claim 1, wherein the weight ratio of water to cement (water / cement =
W / C) is W / C = 0.4 or less, The cement composition characterized by the above-mentioned. 3. A hardened cement product obtained by hardening the cement composition containing the cement water reducing agent according to claim 1.