JP2001302317A - Production process of centrifugally cast concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugally cast concrete production process which enables a large reduction in the amount of sludge discharged in a centrifugal casting stage of concrete. SOLUTION: This production process has a stage for charging concrete which comprises cement and a polymer containing 2-3C polyoxyalkylene groups into a form wherein an aromatic sulfonic acid-based formalin condensation product is added to the concrete in the form when the concrete is charged into the form and/or after completion of the charging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing centrifugally molded concrete capable of reducing sludge discharged during molding.

[0002]

2. Description of the Related Art Sludge discharged during centrifugal molding of concrete products such as poles, piles, fume pipes and the like requires a high processing cost. Therefore, a method has been proposed in which solids in the sludge are condensed on the inner surface of concrete ( JP-A-56-
No. 160358). However, in such a method, the fluctuation due to the centrifugal force and the centrifugation time is large, and further reduction in the amount of discharged sludge and the amount of solid content is required.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing centrifugally molded concrete which can greatly reduce the amount of sludge discharged during centrifugal molding.

[0004]

According to the present invention, there is provided a method for producing a centrifugally formed concrete comprising a step of charging a concrete containing a cement and a polymer containing a polyoxyalkylene group (2 to 3 carbon atoms) into a mold. The present invention relates to a method for producing a centrifugally molded concrete in which an aromatic sulfonic acid-based formalin condensate is added when and / or after putting concrete into a formwork.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to an aromatic sulfonic acid-based formalin condensate when and / or after a concrete containing a polyoxyalkylene group (C2 to C3) -containing polymer is charged into a mold. It has a great feature in adding.

Generally, the amount of sludge discharged during centrifugal molding increases as the fluidity of concrete increases, and decreases as the fluidity decreases. However, concrete whose fluidity has been adjusted to such a degree as to suppress the discharge of sludge cannot be completely filled in the formwork even when poured into the formwork. Therefore, as a result of investigations by the present inventors, when an aromatic sulfonic acid-based formalin condensate is added to concrete containing a polymer containing a polyoxyalkylene group (having 2 to 3 carbon atoms), the polyoxyalkylene group has a polyoxyalkylene group. It has been surprisingly found that the interaction between the alkylene chain and the aromatic ring of the aromatic sulfonic acid-based formalin condensate reduces the fluidity of concrete. Then, utilizing the interaction between the two, by adding an aromatic sulfonic acid-based formalin condensate so that the fluidity of the concrete is reduced after filling the form, the concrete is completely filled in the form. In addition, the amount of sludge discharged during centrifugal molding and its solid content can be reduced.

The polyoxyalkylene group-containing polymer used in the present invention comprises at least one vinyl monomer (a) having an average of 2 to 300 moles of an oxyalkylene group having 2 to 3 carbon atoms, and at least one carboxyl group. Monomer (b) having a sulfonic acid group or an amide group, or a water-soluble salt thereof
A water-soluble copolymer obtained by polymerizing a monomer mixture containing at least one species is preferred.

The vinyl monomer (a) includes a compound represented by the formula (I):

[0009]

Embedded image

Wherein R ¹ and R ² are a hydrogen atom or a methyl group, m ¹ is an integer of 0 to 2, p is an integer of 0 or 1, AO
Is an oxyalkylene group having 2 to 3 carbon atoms, n represents an average addition mole number of AO, 2 to 300, and X represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms). preferable. Incidentally, m ¹ is 0, p is 1, and the oxyalkylene group is preferably an oxyethylene group having 2 carbon atoms. The average number of moles of the oxyalkylene group added, that is, n in the formula (I) is an initial fluidity. From the viewpoint of interaction with the aromatic ring, 100 to 200 is more preferable.

Specific examples of the compound represented by the formula (I) include a polyalkylene glycol having a lower alkyl group blocked at one end, such as methoxypolyethylene glycol, methoxypolypropylene glycol, and ethoxypolyethylene polypropylene glycol, and (meth) acrylic acid. Esterified products and ethylene oxide (E) of (meth) acrylic acid
O), propylene oxide (PO) adduct and the like, and preferably an esterified product of methoxypolyethylene glycol and (meth) acrylic acid. The form of addition of the oxyalkylene group may be single, random, block or alternating.

As the vinyl monomer (a), a single monomer may be used, or a mixture of two or more monomers having different average number of moles of oxyalkylene group and the like may be used. You may.

The vinyl monomer (b) or a water-soluble salt thereof is represented by the formula (II) or (III):

[0014]

Embedded image

Wherein R ³ is a hydrogen atom or a methyl group;
⁴ and R ⁵ is a hydrogen atom, a methyl group or - (CH ^₂₎ m ₂
A group represented by COOM ² , R ⁶ is a hydrogen atom or a methyl group, M ¹ , M ² and Y are a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, and a carbon number 1 to 1 which may have a hydroxyl group. A mono-, di- or trialkylammonium substituted with an alkyl group of 4, m ² represents an integer of 0 to 2) and an acid anhydride thereof, and a compound represented by the formula (II) More preferred.

Examples of the compound of the formula (II) and its acid anhydride include unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; and unsaturated dicarboxylic acids such as maleic acid, itaconic acid, citraconic acid and fumaric acid. Or an anhydride thereof; and an alkali metal salt, an alkaline earth metal salt, an ammonium salt, a mono-, di-, or trialkylammonium salt substituted with an alkyl group having 1 to 4 carbon atoms which may have a hydroxyl group. And more preferably (meth) acrylic acid and alkali metal salts thereof.

Examples of the compound of the formula (III) include allyl sulfonic acid, methallyl sulfonic acid, or an alkali metal salt, an alkaline earth metal salt, an ammonium salt thereof, and a C1 to C4 which may have a hydroxyl group. And mono-, di- and trialkylammonium salts substituted with an alkyl group.

As the vinyl monomer (b), a single monomer may be used, or a mixture of two or more monomers may be used.

The water-soluble copolymer is described in, for example, JP-A-7-2
It can be produced by a solution polymerization method described in JP 238522A and the like. Specifically, for example, a mixture of the above-mentioned monomer, in water or a lower alcohol having 1 to 4 carbon atoms,
In the presence of a polymerization initiator such as ammonium persulfate and hydrogen peroxide, sodium bisulfite, mercaptoethanol and the like are added as necessary, and the reaction is carried out at 50 to 100 ° C. for 0.5 to 10 hours under a nitrogen atmosphere. .

The molar ratio of the vinyl monomer (a) and the vinyl monomer (b) in the monomer mixture constituting the copolymer [monomer (a) / monomer (b)] Is preferably 1/100 to 200/100 in order to suppress sludge discharge,
10/100 to 100/100 are more preferred.

The total content of the vinyl monomer (a) and the vinyl monomer (b) in the monomer mixture is preferably at least 50% by weight, particularly preferably at least 80% by weight. As monomers other than the vinyl monomers (a) and (b),
For example, acrylonitrile, acrylate, (meth) acrylamide, styrene, styrenesulfonic acid and the like can be mentioned.

The weight average molecular weight of the polyoxyalkylene group-containing polymer is adjusted to 5,
000 to 500,000 is preferable, and 20,000 to 1
00,000 is more preferred. The weight average molecular weight is measured by a gel permeation chromatography method (standard substance: sodium polystyrene sulfonate conversion / water system).

The content of the polyoxyalkylene group-containing polymer in the concrete put into the mold is 100 cement
It is preferably 0.05 to 5.0 parts by weight, more preferably 0.1 to 1 part by weight, based on the weight of the solid.

The aromatic sulfonic acid type formalin condensate used in the present invention is a polyoxyalkylene group (having 2 carbon atoms).
-3) It decreases the fluidity of concrete containing the containing polymer, and includes sulfonic acid type formalin condensates such as naphthalene sulfonic acid type, melamine sulfonic acid type and aniline sulfonic acid type. These are alkali metal salts, alkaline earth metal salts, ammonium salts, mono,
Although it may be used as a water-soluble salt such as di- or triethanolamine salt, a water-soluble salt of a naphthalenesulfonic acid formalin condensate is preferred from the viewpoint of interaction with a polyoxyalkylene chain of the polymer. A water-soluble salt of an aromatic sulfonic acid-based formalin condensate can be produced, for example, by sulfonating naphthalene, melamine, aniline, or the like using a sulfonating agent, and then adding and condensing formalin to neutralize the salt. it can.

The amount of the aromatic sulfonic acid-based formalin condensate is determined by the amount of the polyoxyalkylene group-containing polymer 10
1 to 50 parts by weight, preferably 5 to 4 parts by weight, per 0 parts by weight.
0 parts by weight is more preferred.

When putting concrete into the formwork and / or
Alternatively, as a method of adding the aromatic sulfonic acid-based formalin condensate after the addition, for example, preferably 0.01 to 4
An aqueous solution of an aromatic sulfonic acid-based formalin condensate having a concentration of 0% by weight, more preferably a concentration of 1 to 30% by weight (solid content) was charged to the inner surface of the mold before the concrete was poured, or to the mold, or During centrifugal molding, or the method of spraying or spraying on the entire surface of the concrete whose rotation has been stopped during centrifugal molding may be sprayed, but if it is a method that can disperse the aromatic sulfonic acid-based formalin condensate in the concrete There is no particular limitation. As described above, by adding the aromatic sulfonic acid-based formalin condensate when and / or after putting concrete in the formwork,
Concrete can be completely filled in a mold, and the amount of discharged sludge and its solid content at the time of centrifugal molding can be reduced.

The production method of the present invention may be any method that includes a step of adding an aromatic sulfonic acid-formalin condensate at the time of and / or after the concrete is poured into the mold, and the conditions for centrifugal molding and the like are as follows. The method is not particularly limited and can be performed by a conventional method. Accordingly, there is no particular limitation on the concrete composition such as cements, aggregates, and additives (agents).

[0028]

EXAMPLE Production Example of Polymer 8 A reaction vessel was charged with 15 mol of water and placed in a nitrogen atmosphere at 75 ° C.
In Table 1, 0.35 mol of the monomer (a) and 1 mol of the monomer (b) [monomer molar ratio: (a) / (b) = 35 /
100] and 15 mol of water, 0.01 mol of a 20% by weight aqueous solution of ammonium persulfate and 4 g of 2-mercaptoethanol were simultaneously added dropwise over 2 hours. Then
0.03 mol of a 20% by weight aqueous solution of ammonium persulfate
After dropping in 0 minutes and reacting at the same temperature for 1 hour, 95
The temperature was raised to 12 ° C., and 12 g of a 35% by weight hydrogen peroxide solution was added, followed by aging for 2 hours. After aging, the mixture was neutralized by adding a 48% by weight aqueous solution of sodium hydroxide, and polymer 8 (sodium salt) was added.
I got

Method for Producing Polymers 1 to 7, 9 to 14, and 16 Using the monomers shown in Table 1 as monomers (a) and (b), a method according to the production example of polymer 8 As a result, polymers 1 to 7, 9 to 14, and 16 (sodium salt) were obtained.

Table 1 shows the weight average molecular weights of the obtained polymers 1 to 14 and 16. A commercially available polyacrylic acid sodium salt “Poise 530” (manufactured by Kao Corporation) was used for polymer 15
The weight average molecular weight is also shown in Table 1.

[0031]

[Table 1]

Examples 1-22, Comparative Examples 1-3 Normal Portland cement (specific gravity: 3.17) 167 parts by weight, tap water 450 parts by weight, river sand (Kinokawa product, specific gravity:
2.90) 692 parts by weight and crushed stone (from Ibaraki, specific gravity: 2.90)
62) 1056 parts by weight were kneaded with a forced mixer for 90 seconds. Polymers 1 to 16 were added in the amounts shown in Table 2, and the fluidity of the concrete was adjusted so that the slump value measured by JIS-A1101 method was 9.5 cm. 16 kg of the obtained concrete is weighed 200 mm.
After being placed in a centrifugal mold having a size of 300 mm × 300 mm, a 10% by weight (solid content) aqueous solution of an aromatic sulfonic acid-based formalin condensate shown in Table 2 was sprayed on the entire surface of the concrete placed in the mold. .

The concrete to which the aromatic sulfonic acid-based formalin condensate was added was stirred at a low speed (2 G) for 1 minute at a medium speed (8 G).
G) for 1 minute, medium speed (18G) for 2 minutes, and high speed (28G) for 2 minutes, and the discharged sludge amount (g) and the total solid content in the sludge (after drying at 110 ° C for 4 hours (G) was measured. Table 2 shows the results.

In Comparative Example 3, polyacrylamide (Diafloc AP-410: manufactured by Diafloc Co.) was used without using an aromatic sulfonic acid-based formalin condensate.
/ Sodium alkylbenzene sulfonate (Neoperex No. 6: manufactured by Kao Corporation) = 90/10 (weight ratio)
The concrete was centrifugally molded in the same manner as in Example 1 except that 10 ml of a 0.25% by weight aqueous solution was made into 100 ml of foam powder with a juice mixer, and after 1 minute at a low speed (2 G), the mixture was added to the concrete.

[0035]

[Table 2]

From the above results, in each of Examples 1 to 22 and Comparative Examples 1 to 3, although the obtained molded products had smooth inner surfaces and no finishing problem, Comparative Examples 1 and 2 showed that
Since the desired polyoxyalkylene group-containing copolymer was not used, the amount of discharged sludge was large, and in Comparative Example 3, the desired aromatic sulfonic acid-based formalin condensate was not used, and the concrete had a high fluidity. It can be seen that the discharge of sludge is not suppressed because it remains as it is.

[0037]

According to the present invention, it has become possible to provide a method for producing centrifugally molded concrete capable of greatly reducing the amount of sludge discharged during centrifugal molding.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08F 220/00 C08F 220/00 228/02 228/02 C08L 33/02 C08L 33/02 41/00 41 / 00 55/00 55/00 // C08F 290/06 C08F 290/06 C04B 103: 32 C04B 103: 32 111: 56 111: 56 (72) Inventor Akitoshi Tsuji 1334 Minato, Wakayama-shi Kao Corporation Research Institute ( 72) Inventor Yoshikazu Morii 1334 Minato, Wakayama City F-term in Kao Corporation Research Laboratories (reference) 4G012 PA04 PB35 PB36 4G056 AA07 CB32 4J002 BG011 BG071 BH021 BQ001 CH051 DM006 FD016 GL00 4J027 AC02 AC01 BA04 ACO4 BA01 CD06 AJ02Q AJ08Q AJ09Q AL08P AP01Q BA02P BA03P BA08P BA56Q

Claims (5)

[Claims] 1. A method for producing centrifugally molded concrete, comprising a step of charging a concrete containing a cement and a polymer containing a polyoxyalkylene group (2 to 3 carbon atoms) into a mold, wherein the concrete is A method for producing a centrifugally molded concrete, wherein an aromatic sulfonic acid-based formalin condensate is added when and / or after charging. 2. A polyoxyalkylene group-containing polymer,
The average number of oxyalkylene groups having 2 to 3 carbon atoms is 2 to 300.
It contains at least one mol-added vinyl monomer (a) and at least one vinyl monomer (b) having a carboxyl group, a sulfonic acid group or an amide group, or at least one water-soluble salt thereof. The production method according to claim 1, which is a water-soluble copolymer obtained by polymerizing a monomer mixture. 3. A concrete to be poured into a mold, comprising a polyoxyalkylene group-containing polymer in a solid content of 0.05 to 5.0 parts by weight based on 100 parts by weight of cement, and aromatic sulfone. The addition amount of the acid-based formalin condensate is
The production method according to claim 1 or 2, wherein the amount is 1 to 50 parts by weight based on 100 parts by weight of the polyoxyalkylene group-containing polymer. 4. The process according to claim 1, wherein the aromatic sulfonic acid formalin condensate is a water-soluble salt of naphthalene sulfonic acid formalin condensate. 5. A method according to claim 1, wherein the vinyl monomer (a) is of the formula (I): (Wherein, R ¹ and R ² are a hydrogen atom or a methyl group, m ¹ is an integer of 0 to 2, p is an integer of 0 or 1, AO is a carbon atom of 2 to 2)
An oxyalkylene group of 3, n represents the average number of moles of AO added, a number of 2 to 300, X represents a hydrogen atom or a carbon atom of 1 to 3
Wherein the vinyl monomer (b) or a water-soluble salt thereof is represented by the formula (II) or (III):
: (Wherein, R ³ is a hydrogen atom or a methyl group, R ⁴ and R ⁵ are a hydrogen atom, a methyl group or a group represented by — (CH ₂ ) m ² COOM ² , R ⁶ is a hydrogen atom or a methyl group, M ^1, M ²
And Y are a hydrogen atom, an alkali metal, an alkaline earth metal,
Ammonium, 1-4 carbon atoms which may have a hydroxyl group
The method for producing mono-substituted with an alkyl group, di- or trialkyl ammonium, m ² is according to any one of claims 2-4 which is a compound or an acid anhydride represented by the show) an integer of 0-2.