JPH1179812A - Agent for reinforcing concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a concrete-reinforcing agent making possible to control the flowability, coagulability and strength expression of a cement composition and improve the workability and application time shortage of the cement composition by including a specific cement water reducer and a soluble calcium salt. SOLUTION: This agent for reinforcing concrete comprises a cement water reducer and a soluble calcium salt in a weight ratio of 0.2-20. The cement reducer comprises the formaldehyde cocondensate of the glycidyl adduct of a polyoxyalkylenediamine compound of the formula [R1 is a 1-5C alkyl; R2 is H, a 1-10C alkyl or phenyl; AO and BO are each a 2-5C oxyalkylene in a block or random form; (m) and (n) are each 0-200, 200>=(m)+(n)>=4], a monomer capable of being subjected to a formaldehyde cocondensation reaction with the glycidyl ether adduct of the polyoxyalkylenediamine, and a compound producing a sulfone group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an additive for cement, and more particularly, to an additive for a cement composition such as cement paste, mortar, and concrete to control the fluidity, setting property and strength of the cement composition. The present invention relates to a cement reinforcing agent capable of greatly improving workability and shortening construction time.

[0002]

2. Description of the Related Art Conventionally, a cement dispersant (water reducing agent) has been used to impart fluidity to a cement composition such as cement paste, mortar, concrete, etc. to improve workability or to obtain high strength by a water reducing effect. On the other hand, soluble calcium salts such as calcium chloride and calcium nitrite are used as an accelerator to obtain strength early in an emergency construction or the like.

[0003]

However, conventionally, when a cement water reducing agent is combined with a soluble calcium salt, the water reducing agent has a cement setting delaying action, so that a large amount of a soluble calcium salt as a setting accelerator is required. In the meantime, there was a problem that the fluidity of the cement was impaired. For example,
It is known that the mortar flow is reduced when a conventional water reducing agent is used in combination with a soluble calcium salt such as calcium chloride, calcium formate, or calcium nitrite (Cement Technology Annual Report 28, p256, published in 1974). This water reducing agent is a formalin condensate of an aromatic sulfonic acid, and it is considered that hydration is promoted by a soluble calcium salt and fluidity is reduced.

[0004] Further, the fluidity of the cement composition is ensured,
As a method of obtaining early strength development, a method of using a combination of a fluidizing agent comprising a copolymer containing a polyoxyalkylene compound and maleic anhydride as essential components and calcium nitrite as a setting accelerator is disclosed in Japanese Patent Application Laid-Open No. HEI-5-205. -213652. However, it has long been known that compounds containing a carboxyl group, such as maleic anhydride, delay the setting of cement to a considerable extent (see “Cement / Concrete Chemistry and its Applications”, pp. 86-92,
Therefore, this method also has a problem that the required amount of calcium nitrite increases or slump loss due to calcium nitrite increases.

As described above, conventionally, when a co-condensate of aromatic sulfonic acid is used as a water reducing agent for cement and is combined with a soluble calcium salt, fluidization is reduced.
When a carboxyl group-containing compound and a soluble calcium salt are combined, there is a problem that the setting retardation effect is impaired and the initial strength is reduced.

[0006]

In order to solve these problems, the present inventors have replaced the conventional formaldehyde cocondensate of aromatic sulfonic acid with a polyoxyalkylene group by co-condensation reaction of a polyoxyalkylene diamine compound or polyoxyalkylene glycidyl. Formaldehyde co-condensate introduced by the addition reaction of an ether compound, a compound having a sulfone group in the co-condensate is used as a water reducing agent, and by combining this with a soluble calcium salt, the setting time is short, and the strength is developed. It has been found that a cement reinforcing agent which is excellent in water resistance and more excellent in fluidity than when the water reducing agent is used without a soluble calcium salt can be obtained. The present invention solves the conventional problems based on the above findings, and provides a cement reinforcing agent which is excellent in setting and strength development and has good fluidity.

That is, according to the present invention, there are provided the following cement reinforcing agents described in claims 1 and 2. (1) A cement reinforcing agent comprising a cement water reducing agent and a soluble calcium salt, wherein the cement water reducing agent is capable of co-condensing glycidyl ether adduct to polyoxyalkylenediamine and glycidyl ether adduct of polyoxyalkylenediamine with formaldehyde. A cement reinforcing agent characterized in that it is a formaldehyde co-condensate with a suitable monomer and a compound generating a sulfone group. (2) A cement reinforcing agent comprising a cement water reducing agent and a soluble calcium salt, wherein the cement water reducing agent is capable of undergoing an addition reaction to polyoxyalkylene monoglycidyl ether, polyoxyalkylene glycidyl ether,
And a formaldehyde co-condensate with a compound generating a sulfone group.

Further, according to the present invention, claims
The following preferred embodiments of the cement reinforcing agent described in above are provided. (3) The monomer capable of formaldehyde co-condensation of (1) is one or more selected from melamine or a derivative thereof, phenol or a derivative thereof, urea or a derivative thereof, aminobenzenesulfonic acid or a derivative thereof. (1) The cement reinforcing agent according to (1), comprising a cement water reducing agent and a soluble calcium salt. (4) The monomer capable of the addition reaction of (2) is one or two or more selected from melamine or a derivative thereof, phenol or a derivative thereof, urea or a derivative thereof, and aminobenzenesulfonic acid or a derivative thereof. (2) The cement reinforcing agent according to (2), comprising a cement water reducing agent and a soluble calcium salt. (5) The cement water reducing agent and the soluble calcium salt of (1), (2), (3) and (4) are characterized in that the ratio of soluble calcium salt / water reducing agent = 0.2 to 20 by weight ratio. Cement reinforcement.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When a polyoxyalkylene group is introduced into a cement water reducing agent, a conventional polyoxyalkylene group can be introduced as a copolymerizable compound of maleic anhydride or acrylic acid. In this case, maleic anhydride or acrylic acid which delays the setting enters as an essential component. Particularly, in the maleic anhydride copolymer, the molar ratio of maleic anhydride needs to be 1 or more with respect to the copolymerizable polyoxyalkylene compound. As a result, the number of carboxyl groups in the water reducing agent increases. Will delay the setting of the cement.

Unlike such a copolymer having a carboxyl group, the formaldehyde condensate does not use maleic anhydride or acrylic acid, which has a large setting delaying action, as an essential component, and is used together with a soluble calcium salt as a setting accelerator. However, the effect of accelerating the setting is not hindered, and a cement reinforcing agent which is rich in fluidity and excellent in strength development can be obtained.

Therefore, the cement reinforcing agent of the present invention is a co-condensate in which a polyoxyalkylene group is introduced by a co-condensation reaction of a polyoxyalkylene diamine compound or an addition reaction of a polyoxyalkylene glycidyl ether compound. A compound having a sulfone group therein is used as a water reducing agent, and this is used in combination with a soluble calcium salt.

The polyoxyalkylene group in the polyoxyalkylene diamine compound or the polyoxyalkylene glycidyl ether compound is an oxyalkylene group having 1 to 2 or more kinds of blocks having 2 to 5 carbon atoms or a randomly bonded oxyalkylene group. Is preferably 4 to 200. When the number of carbon atoms of the oxyalkylene exceeds 5, the fluidity effect is reduced. When the number of repeating units is less than 4, the fluidity effect and the slump loss suppressing effect are not sufficient. Decrease. Further, those having 20 or more polyoxyalkylene repeating units have high separation resistance and are suitable for high fluidity concrete, especially when used for concrete.

The above polyoxyalkylenediamine compound is preferably a compound represented by the general formula A in Chemical formula 1.

[0014]

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As the above polyoxyalkylene glycidyl ether compound, those represented by the general formula B in Chemical formula 2 are preferred.

[0016]

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Monomers capable of undergoing a co-condensation reaction with the polyoxyalkylene diamine compound and formaldehyde, or capable of undergoing an addition reaction of the polyoxyalkylene glycidyl ether compound include melanin or a derivative thereof, phenol or a derivative thereof, and urea or a derivative thereof. , Aminobenzenesulfonic acid or a derivative thereof can be used, and two or more monomers can be used in combination.

As the above-mentioned monomer melanin or a derivative thereof, those represented by the general formula C of Chemical Formula 3 are preferred.

[0019]

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As the above-mentioned monomer phenol or a derivative thereof, those represented by the general formula D of Chemical Formula 4 are preferred.

[0021]

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The above-mentioned monomer urea or its derivative is preferably represented by the general formula (E).

[0023]

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The above-mentioned monomer, aminobenzenesulfonic acid or a derivative thereof, is preferably represented by the following general formula (F).

[0025]

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As the compound for forming a sulfone group in the co-condensate, one or more of sodium sulfite, sodium bisulfite, sodium pyrosulfite, fuming sulfuric acid, sulfur dioxide and the like can be used. The sulfone groups introduced into the co-condensate stably disperse the cement and improve the dispersing ability.

A production example of the water reducing agent used in the cement reinforcing agent of the present invention is described in JP-A-9-132443, but it is not known to use it in combination with a soluble calcium salt.

As the soluble calcium salt to be combined with the above water reducing agent comprising formaldehyde co-condensate, calcium chloride, calcium nitrate, calcium nitrite, calcium formate, calcium bromide, calcium iodide, calcium sulfamate and the like can be used. it can. The higher the solubility of these soluble calcium salts, the greater the effect. Incidentally, two or more of the above-mentioned soluble calcium salts may be used in combination.

Of the above-mentioned soluble calcium salts, calcium chloride is economical, but is not preferred because cement induces rust in the reinforcing steel, and its use is not limited to the case where cement is used other than reinforced concrete, for example, unreinforced concrete, glass. Use is limited to fiber reinforced concrete, carbon fiber concrete, etc.

Calcium nitrite has a rust-preventing effect and is one of the most suitable for use in combination with the present water reducing agent. Further, if calcium chloride and calcium nitrite are used in combination, even when used for reinforced concrete, it is possible to suppress the induction of rust on the reinforcing bar and to make it economical.

When the amount of the soluble calcium salt is small, there is no effect of improving the initial fluidity. However, when the amount is large, the water loss is impaired, which is not appropriate. A preferable addition amount is, by weight ratio, soluble calcium salt / water reducing agent = 0.2 to
A range of 20 is practical.

The ratio of the water reducing agent to the cement in the cement reinforcing agent of the present invention is suitably 0.01 to 1 part by weight based on the cement as a solid content of the water reducing agent. If the amount is less than 0.01%, water reducing performance cannot be provided, and if it exceeds 1%, the necessary amount of soluble calcium used in combination increases, which is uneconomical.

The cement reinforcing agent of the present invention comprising a combination of the above-mentioned water reducing agent and a soluble calcium salt is usually used for portland cements such as high strength, moderate heat, belite, etc., and blast furnace slag which is a fine powder of minerals. It can be widely used for various cements such as mixed cement containing fly ash, silica fume, limestone, etc. or rapid-hardening cement containing aluminate mineral, and has the effect of shortening the setting time of these cements and promoting the development of strength. In addition to the above, excellent effects such as an increase in fluidity and an extension of fluidity retention time are exhibited.

In addition, cement mixtures such as mortar and concrete containing the cement reinforcing agent of the present invention have the effects of shortening the setting time, promoting the development of strength, and further increasing the fluidity. Excellent effects such as extension of fluidity retention time are provided.

The cement reinforcing agent of the present invention may be added to the cement composition by previously mixing the water reducing agent and the soluble calcium salt, which are the components thereof, or may be used by adding these individually. good. Furthermore, the water reducing agent and the soluble calcium salt may be added to a cement composition containing no water, such as cement powder or dry mortar, simultaneously or individually.

[0036]

EXAMPLE A butyl glycidyl ether adduct of a polyoxyalkylene diamine having a molar average molecular weight of 1,000 and a polyoxyalkylene of polyoxyethylene and polyoxypropylene in a weight ratio of 1 to 10, melamine, phenol and A formaldehyde co-condensate was obtained, and a compound (compound A) in which a sulfone group was formed using anhydrous sodium bisulfite was used as a cement water reducing agent,
The water reducing agent and the soluble calcium salt were combined with 1 part by weight of Portland cement, 2.5 parts by weight of Ogasa land sand, and 0.4 part of water.
The mixture was kneaded in a mortar consisting of parts by weight, and the flow value immediately after kneading and after 60 minutes and the compressive strength 8 hours after kneading were measured in accordance with Japanese Industrial Standards (JIS R 5201). As the soluble calcium, 0.01 parts by weight of calcium nitrite, calcium chloride or calcium acetate was used. The addition amount of the water reducing agent was determined so that the flow value immediately after kneading was 250 mm ± 10 mm, and the addition amount is shown in Table 1.

For comparison, a polycarboxylic acid-based water reducing agent having a polyoxyalkylene and a carboxyl group in the structure (trade name: HP-11, manufactured by Takemoto Yushi Co., Ltd.) and a polyoxyalkylene were also included in the structure. Formaldehyde cocondensate of aromatic sulfonic acid (Mighty 15
0, manufactured by Kao Corporation) as a water-reducing agent, or without adding a soluble calcium salt. The results are shown in Table 1.

[0038]

[Table 1]

[0039]

Industrial Applicability The cement reinforcing agent of the present invention has the effects of shortening the setting time of cement compositions such as cement paste, mortar and concrete, promoting the development of strength, and further increasing the fluidity and the flowability. It has excellent effects such as extension of the property retention time. Therefore, this cement reinforcing agent itself can be effectively used as a water reducing agent for ready-mixed concrete, a superplasticizer, a high-performance AE water reducing agent, and as a water reducing agent for premix products used for mortar, floor finishing, grout, etc. The pumping performance is also excellent, which has the effect of significantly improving the workability in civil engineering and construction-related works. Furthermore, the cement reinforcing agent of the present invention can shorten the setting time and promote the development of strength, thereby shortening the steam curing time of concrete products requiring steam curing and promoting the development of long-term strength.

Claims (5)

[Claims] 1. A cement reinforcing agent comprising a cement water reducing agent and a soluble calcium salt, wherein the cement water reducing agent is a glycidyl ether adduct to polyoxyalkylenediamine, a glycidyl ether adduct of polyoxyalkylenediamine and formaldehyde cocondensation. Monomer capable of
And a formaldehyde co-condensate with a compound generating a sulfone group. 2. A cement reinforcing agent comprising a cement water reducing agent and a soluble calcium salt, wherein the cement water reducing agent is capable of undergoing an addition reaction to polyoxyalkylene monoglycidyl ether, polyoxyalkylene glycidyl ether, and A cement reinforcing agent, which is a formaldehyde co-condensate with a compound that generates a sulfone group. 3. The monomer of claim 1, wherein the monomer capable of formaldehyde cocondensation is one or two selected from melamine or a derivative thereof, phenol or a derivative thereof, urea or a derivative thereof, aminobenzenesulfonic acid or a derivative thereof. The cement reinforcing agent according to claim 1, comprising a cement water reducing agent which is at least one kind of compound and a soluble calcium salt. 4. The monomer capable of undergoing the addition reaction according to claim 2,
It comprises one or more compounds selected from melamine or a derivative thereof, phenol or a derivative thereof, urea or a derivative thereof, aminobenzenesulfonic acid or a derivative thereof, or a cement water-reducing agent and a soluble calcium salt. 3. The cement reinforcing agent according to claim 2. 5. The cement water reducing agent and the soluble calcium salt according to claim 1, 2, 3, or 4 are in a ratio of soluble calcium salt / water reducing agent = 0.2 to 20 by weight ratio. A cement reinforcing agent.