JP3424252B2 - Super-bend strength cement molding with excellent water resistance - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement molding having excellent water resistance and extremely high bending strength, that is, having a super bending strength. Can be widely used in the construction industry, including various interior and exterior materials, permanent forms for placing concrete, and high-rise building members. 2. Description of the Related Art Cement, water, fine aggregate and coarse aggregate are produced by mixing cement, water, fine aggregate and coarse aggregate in a molded body using cement as a binder. There is a cement mortar manufactured by mixing, and a cement paste manufactured by mixing cement and water. In general, the strength of a cement molded body increases as the weight part of water relative to 100 weight parts of cement, that is, the water-cement ratio becomes smaller. However, as the water-cement ratio decreases,
Because the fluidity of the mixture consisting of cement and water decreases,
In order to produce a molded article having a high strength and a low water cement ratio, it is necessary to use a water reducing agent or to use a special molding method. On the other hand, even in a cement molded body manufactured by considerably lowering the water cement ratio, since there are voids and water voids therein,
There is a limit in strength. Therefore, in order to reduce the water-cement ratio for the purpose of a cement molded body having super bending strength, a water-reducing agent is added, a water-soluble polymer is mixed, and mechanochemical mixing is performed. A method has been developed for removing voids and water gaps in a cement molded article by a method such as passing through a cement. Such a cement molded article having almost no voids or water gaps is particularly suitable for M
It is called DF (Macrodefect-free) cement, and the bending strength of a molded body obtained after moist air and heat curing reaches several hundred kgf / cm ² . [0003] The super-flexural strength of MDF cement can be reduced not only by reducing the water-cement ratio by using a water reducing agent, but also by using a water-soluble polymer in combination and further passing through a forming roller. This has been achieved by densifying the cement structure, and the water-soluble polymer allows such molding. That is, without using a water-soluble polymer, it is impossible to produce an MDF cement molded article having a super bending strength. However, due to the fact that the polymer used is water-soluble, the MDF cement molded body produced by the conventional method is inferior in water resistance, and the MDF cement molded body obtained after humid air and heat curing is less than 1%.
The flexural strength after immersion in water for a week decreases to several tenths or less before immersion. Therefore, the MDF cement molded body manufactured by the conventional method has been limited to applications in a low humidity environment where the influence of moisture is small. [0004] The inventors of the present invention have conducted intensive studies in order to find a cement molded body having excellent water resistance and superbending strength, which does not lower the bending strength even in a high humidity environment. [0005] To solve the above-mentioned problems, the present inventors have found that the decrease in water resistance due to the use of a water-soluble polymer in a cement molded product is caused by the decrease in the cement content of the cement molded product. Focusing on the cause due to insufficient progress of hydration, various means for promoting the hydration were examined.
As a result, the molded body produced by the specific curing has a bending strength of 3 despite the use of the water-soluble polymer.
The present invention was found to be a molded article having a water resistance of not less than 00 kgf / cm ^2, exhibiting no significant decrease in strength even after immersion in water, and having excellent water resistance. That is, according to the present invention, polyethylene oxide, polyacrylamide,
And acrylamide, methyl acrylate and acrylic
Ternary amide dimethyl ammonium chloride
Selected from the group of polymers and aggregate cement particles
After adding and mixing 0.5 to 10 parts by weight of a water-soluble polymer having performance, 8 to 20 parts by weight of water is added, and the mixture is kneaded and molded. The molded article is 1 kgf / cm ² at 110 ° C. or more and a gauge pressure.
The present invention relates to a super-bending-strength cement molded article excellent in water resistance, which is cured in high-temperature high-pressure steam. Hereinafter, the present invention will be described in detail. Cement As the cement in the present invention, cement generally and widely used in the construction industry can be used.
Specific examples of the cement include ordinary Portland cement, white cement, early-strength Portland cement, ultra-fast curing cement, moderate heat Portland cement, alumina cement, silica fume cement, fly ash cement and the like. Any of these cements can be used in the present invention, but in order to obtain higher effects, it is preferable to use alumina cement, early-strength Portland cement, silica fume cement, or the like. Water-soluble polymer The water-soluble polymer in the present invention functions as a molding aid for a cement molded article, and any of those having a function of coagulating cement particles can be used.
A copolymer of a water-soluble monomer and a water-insoluble monomer can be used as long as the polymer is water-soluble. Specifically, polyethylene oxide, polyacrylamide, polyvinyl acetate, polyacrylate, or the like, or a copolymer of two or more of the monomers constituting these polymers, or a monomer constituting these polymers And a polymer obtained by copolymerizing a polymer with an acrylate, methacrylate, unsaturated sulfonate, acrylonitrile, styrene, or the like. These water-soluble polymers can be used in combination of two or more. Other examples of the water-soluble polymer include cellulose ether polymers such as methylcellulose, hydroxyethylcellulose and carboxymethylcellulose, which cannot be copolymerized with the monomers constituting the above-mentioned polymers, but may be used alone or as the above-mentioned water-soluble polymer. Can be used in combination. Particularly preferred water-soluble polymers are polyethylene oxide, polyacrylamide, and terpolymers of acrylamide, methyl acrylate and acrylamidodimethylammonium chloride. The degree of polymerization of the water-soluble polymer depends on the type and structure, but is preferably 100 or more. When the degree of polymerization is less than 100, the properties as a polymer are not sufficiently exhibited. In the present invention, the amount of the water-soluble polymer added to the cement must be 0.5 to 10 parts by weight, preferably 0.8 to 6 parts by weight, based on 100 parts by weight of the cement. When the addition amount is less than 0.5 parts by weight, the expression of bending strength becomes insufficient. On the other hand, when the amount exceeds 10 parts by weight, even if the flexural strength is sufficiently developed, the water resistance is lowered, and this is not practical. ○ Other additives In the present invention, an extender, a reinforcing material, a coloring agent and the like can be used as required. Examples of fillers include silica sand, talc, calcium carbonate, gypsum, diatomaceous earth, titanium oxide, silica, pearlite, and inorganic powders such as mica. Examples of the reinforcing material include fibrous materials such as glass fiber, carbon fiber, and vinylon fiber.
Examples of the colorant include various inorganic pigments such as carbon black, triiron tetroxide, and zinc white. In addition, carbon black, ferrite, or the like may be added to impart conductivity, or a high-toughness water-insoluble resin such as an epoxy resin may be added to improve toughness. Manufacturing method The super-bending strength cement molded product of the present invention is prepared by adding cement, a water-soluble polymer and, if necessary, an extender or the like, kneading without adding water, and then adding water. In addition, it is manufactured by kneading and then molding. By kneading the cement and the water-soluble polymer before water injection, the water-soluble polymer is dispersed throughout the cement molded body, and has an effect obtained by mechanochemical mixing, and has a super bending strength intended for the present invention. A molded article can be manufactured. Conversely, if a water-soluble polymer is added to and mixed with a mixture obtained by kneading and mixing cement and water, the polymer is unevenly distributed in the molded body, and sufficient strength cannot be obtained. The smaller the amount of water required for mixing the cement, the higher the strength. Specifically, the amount is preferably 8 to 20 parts by weight, more preferably 8 to 15 parts by weight, based on cement. It is preferable to use a water reducing agent or a fluidizing agent for cement concrete at the time of kneading because the amount of water used can be reduced. As the water reducing agent and the fluidizing agent, commercially available general ones can be used. Next, a mixture obtained by kneading and mixing the cement and the water-soluble polymer with water is formed into a molded product, and various molding methods can be employed, and specific examples include extrusion molding, cast molding, and press molding. Any of the molding methods can be used, but in order to obtain super bending strength, a molding method capable of removing voids and water gaps as much as possible in the molding process is preferable. The molded article obtained by the present invention becomes a super-bending strength cement molded article having excellent water resistance by being cured in high-temperature and high-pressure steam despite the use of a water-soluble polymer. The curing pressure is 1 gauge pressure.
kgf / cm ² or more, more preferably 1.5 kgf / cm
cm ² or more. If the curing pressure is less than 1 kgf / cm ² in terms of gauge pressure, as the temperature is increased, water will escape from inside the molded product before curing of the molded product proceeds, and the strength of the obtained molded product will not be sufficiently increased. The curing temperature is 1
Must be at least 10 ° C. If the curing temperature is lower than 110 ° C., curing is performed for several hours, and the water-soluble polymer in the molded article is dissolved in water, and the water resistance is not improved. If the temperature is too high, the cement starts to decompose. The appropriate curing time depends on the pressure and temperature employed, but generally tends to be shorter as the pressure and temperature are both higher. As the curing time, the pressure is 3 kgf / cm ² or more in gauge pressure and the temperature is 110 to 300 ° C.
It is preferably 10 to 10 hours. In the present invention, curing of the molded article in high-temperature and high-pressure steam is usually performed in an autoclave. Autoclaves generally have 5-10
a low pressure used in kgf / cm ^2, there is high pressure used in 10~500kgf / cm ^2, in the present invention is sufficient for a low pressure.
Before curing the molded article in high-temperature and high-pressure steam, the temperature is 20 ° C.
After leaving the molded article in an environment of about 80 ° C. and a humidity of 80% or more, preferably for a period of 1 day or more, more preferably 3 days or more,
Precuring by exposing to a temperature of about 50 ° C. is preferable because the bending strength of the obtained molded body is improved. The present invention will be described more specifically with reference to examples and comparative examples. The residual ratio of strength after immersion in Tables 1, 2 and 3 was calculated by the following equation. Equation 1 Example 1 A polymerization degree of about 7 was added to 100 parts by weight of ordinary Portland cement.
4 parts by weight of polyacrylamide powder
After kneading for 1 minute, 14 parts by weight of tap water and 1 part by weight of a polyalkylallyl sulfonate-based high-performance water reducing agent (Mighty 150, manufactured by Kao Corporation) are added and kneaded and mixed for 10 minutes to prepare a cement paste. did. The prepared cement paste was formed into a sheet using a twin roll mill, and a molded product having a size of 25 × 100 × 2 mm was obtained. After the molded article was cured in an environment of a temperature of 20 ° C. and a humidity of 80% for 7 days and subsequently at a temperature of 45 ° C. for 1 day, the molded article was put in an autoclave at a gauge pressure of 10 using steam.
Cured at kgf / cm ^{2 at} a temperature of 180 ° C. for 5 hours to obtain a molded body.
The bending strength of the obtained molded body was 360 kgf / cm ² .
After the molded article was immersed in water for 48 hours, the flexural strength was measured to be 360 kgf / cm ² , and there was no decrease in strength due to immersion in water. Examples 2 and 3 Except for using alumina cement as cement (Example 2) or using silica fume cement in which silica fume was mixed with ordinary Portland cement at 1% by weight (Example 3), A cement molding was produced under the same conditions as in Example 1. Table 1 shows the bending strength of the obtained molded body and the bending strength after immersion in water. [Table 1] Examples 4 and 5 Either using polyethylene oxide as the water-soluble polymer (Example 4) or copolymerizing acrylamide, methyl acrylate and acrylamide dimethylammonium chloride in a molar ratio of 85:10 to 5 respectively. Except for using a dried and pulverized terpolymer (Example 5),
A cement molding was manufactured under the same conditions as in Example 1. Table 1 shows the bending strength of the obtained molded body and the bending strength after immersion in water.
Shown in Examples 6 and 7 Cement molded bodies were produced under the same conditions as in Example 1 except that the amount of the water-soluble polymer was changed to 10 parts by weight or 1 part by weight. Table 1 shows the bending strength of the obtained molded body and the bending strength after immersion in water. Examples 8 and 9 Curing conditions were 10 kgf / cm ² at gauge pressure and 24 at 110 ° C.
A cement molded body was manufactured under the same conditions as in Example 1 except that the time was set (Example 8) or the gauge pressure was changed to 3 kgf / cm ² and the temperature was set to 220 ° C. for 5 hours (Example 9). Table 1 shows the bending strength of the obtained molded body and the bending strength after immersion in water. As is clear from the above examples, all of the cement molded articles of the present invention hardly decrease in strength due to immersion in water and are excellent as high strength water resistant molded articles. Comparative Example 1 A cement molding was produced under the same conditions as in Example 1 except that curing was not performed with high-temperature, high-pressure steam. The bending strength of the obtained molded body was 810 kgf / cm ² , but the bending strength after immersion in water was not more than 10 kgf / cm ² , so that it was not practically usable. Comparative Example 2 A temperature of 20 ° C. and a humidity of 80% without curing with high temperature and high pressure steam
A cement molding was produced under the same conditions as in Example 1 except that curing was performed for 28 days. As shown in Table 3, the bending strength of the obtained molded body was 700 kgf / cm ² , but the bending strength after immersion in water was about 100 kgf / cm ^2. It was not tolerable. Comparative Examples 3 and 4 The same conditions as in Example 1 except that the amount of the water-soluble polymer was 0.3 parts by weight (Comparative Example 3) or 15 parts by weight (Comparative Example 4). To produce a cement molding. Table 3 shows the bending strength of the obtained molded body and the bending strength after immersion in water. [Table 3] Comparative Examples 5 and 6 Curing conditions were 0.9 kgf / cm ² at a gauge pressure and 24 at 110 ° C.
Time (Comparative Example 5) or 5 kgf / cm ² at gauge pressure,
Example 1 except for 24 hours at 90 ° C. (Comparative Example 6)
A cement molded body was manufactured under the same conditions as described above. Table 3 shows the bending strength of the obtained molded body and the bending strength after immersion in water.
As is clear from each of the above comparative examples, the bending strength after immersion in water is 60% or less of that before immersion in water in any case, and is not practical. According to the present invention, it has excellent bending strength,
Further, even in a high humidity environment, the bending strength is not reduced, and it is possible to provide a super-bending strength cement molded article excellent in water resistance, and the super-bending strength cement molded article of the present invention can be used in a high humidity environment. It can be used for a wide range of applications such as construction members that can be used below. [Table 2]

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masafumi Achinami 1 East, Funamicho, Minato-ku, Nagoya-shi, Aichi Prefecture Nagoya Research Institute (72) Inventor Tokimoto Amano Port of Nagoya-shi, Aichi 1 Togo Aseisei Chemical Industry Co., Ltd. Nagoya Research Center, 1 Funami-cho, Ward (56) References JP-A-59-223261 (JP, A) JP-A-3-80141 (JP, A) JP-A-3- 161304 (JP, A) JP-A-57-43805 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 40/02 C04B 24/24-24/38 C04B 28/02- 28/12

Claims (1)

(57) [Claims] [Claim 1] Polyethylene is added to 100 parts by weight of cement.
Oxide, polyacrylamide and acrylamide
Amide, methyl acrylate and acrylamide dimethyla
Selected from the group of terpolymers composed of ammonium chloride
After adding and mixing 0.5 to 10 parts by weight of a water-soluble polymer having a function of aggregating cement particles , water 8
-20 parts by weight , kneading and mixing.
A super-bending-strength cement molding excellent in water resistance characterized in being cured in high-temperature, high-pressure steam of 0 ° C. or more and a gauge pressure of 1 kgf / cm ² or more.