JPH0250068B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a cured cement product at low temperatures, and more specifically, the present invention relates to a method for producing a cured cement product at low temperatures, and more specifically, a water-soluble salt of a copolymer of a high performance water reducer (A), a chain olefin, and an ethylenically unsaturated dicarboxylic acid anhydride as a water reducer component. This invention relates to a method for producing a hardened cement product that is cast at low temperatures using (B) in combination. Conventionally, hardened cement products produced at low temperatures below 5°C have a water-to-cement ratio (W/
It is necessary to increase the initial strength by lowering C). In particular, secondary concrete products that require high strength and highly fluidized concrete require an extremely small water-cement ratio. For this reason, various water reducing agents have been developed, and among them, high performance water reducing agents that provide high dispersibility without slowing setting or increasing the amount of air entrainment are currently in wide use. However, although known high performance water reducing agents such as naphthalene sulfonate formalin condensate type and melamine sulfonate formalin condensate type show excellent water reducing effect at room temperature, their water reducing effect is reduced at low temperature below 5℃. It has the major drawback of being significantly reduced. Therefore, a method has been proposed in which such a high-performance water reducing agent is used in combination with a small amount of gluconate (Japanese Patent Laid-Open No. 164052/1983), but even this method is not necessarily sufficient as a measure to prevent the water reduction effect from decreasing. I can't say that. Therefore, the inventors of the present invention have conducted intensive studies to overcome these drawbacks of the conventional technology, and have found that a high performance water reducing agent (A), a chain olefin, and an ethylenically unsaturated dicarbonate are used as water reducing agent components when pouring at low temperatures. When used in combination with the water-soluble salt of acid anhydride copolymer (B) in a specific ratio, it is possible to prevent the water-reducing effect from decreasing.
without reducing workability during pouring.
The inventors have also discovered that a cured concrete product with high initial strength and long-term strength can be obtained, and have completed the present invention. Thus, according to the present invention, when producing a hardened cement product by kneading cement, a water reducing agent component, water, and a desired compounding agent and then casting at a temperature of 5° C. or lower, a high performance water reducing agent (A) is added as a water reducing agent component. ) and carbon number 4
The water-soluble salt (B) of the copolymer of chain olefin and ethylenically unsaturated dicarboxylic acid anhydride of ~6 to (A) component 95
Provided is a method for producing a cured cement product at low temperatures, characterized in that component (B) is used in combination at a ratio of ~70% by weight and component (B) in a ratio of 5 to 30% by weight. In the present invention, a cement mixture is obtained by first adding water, a water reducing agent component, and a desired compounding agent to cement and kneading the mixture. The cement used may be any commonly used cement, such as ordinary Portland cement, early strength Portland cement, blast furnace cement,
Examples include fly ash cement, jet cement, expansive cement, and super early strength cement. In addition, the water reducing agent component is a high performance water reducing agent (A) in an amount of 95 to 70% by weight, preferably 90 to 75% by weight, and a water solubility of a chain olefin having 4 to 6 carbon atoms and an ethylenically unsaturated dicarboxylic acid anhydride copolymer. It consists of 5 to 30% by weight of salt (B), preferably 10 to 25% by weight, and 0.01 to 5% by weight of solids, preferably 0.01 to 5% by weight of cement.
It is added in a proportion of 0.1 to 2% by weight. At this time, the usage ratio of component (A) and component (B) is an important requirement; if the ratio of component (A) becomes too large, the water reduction performance at low temperatures will decrease, and if the amount added is increased, air entrainment will occur. The amount increases, and the initial strength of the hardened cement product decreases. The component (A) used may be any one commonly used as a high-performance water reducing agent, and specific examples thereof include formalin condensates of naphthalene sulfonates, formalin condensates of methylnaphthalene sulfonates, Formalin condensates of alkylaryl sulfonates, formalin condensates of melamine sulfonates, etc. are listed, and representative commercial products include Mighty-150 (manufactured by Kao Soap Co., Ltd.),
Examples include Melment F-10 (manufactured by Showa Denko). On the other hand, component (B) is a water-soluble salt of a copolymer of a chain olefin having 4 to 6 carbon atoms and an ethylenically unsaturated dicarboxylic acid anhydride. Here, as the chain olefin having 4 to 6 carbon atoms, butene-1, butene-2,
Isobutylene, pentene-1, pentene-2, 2
-Methyl-butene-1,2-methyl-butene-
Examples include 2,4-methyl-pentene-1, hexene-1, and mixtures thereof, and examples of ethylenically unsaturated dicarboxylic acid anhydrides include maleic anhydride, itaconic anhydride, citraconic anhydride, etc. However, maleic anhydride is particularly advantageous industrially. Such a copolymer salt is prepared by radically copolymerizing a mixture of the chain olefin and an ethylenically unsaturated dicarboxylic acid anhydride, and hydrating the copolymer in the presence of a base such as sodium hydroxide, potassium hydroxide, or ammonia. It can be produced by decomposition. Here, the charging ratio of ethylenically unsaturated dicarboxylic acid anhydride to chain olefin can be selected as appropriate, but preferably 30 to 70:70 to 30 (molar ratio), more preferably a mixture of approximately equimolar ratio is used. . The molecular weight of the copolymer used can be appropriately determined depending on the compounding conditions actually used, but it is usually 300 to 300 as determined by the number average molecular weight determined by vapor pressure osmosis.
50,000, preferably 1,000 to 20,000.
Further, a part of this copolymer may be esterified, amidated or imidized and used as long as the effects of the present invention are not essentially impaired. The method of adding component (A) and component (B) is not particularly limited, and may be either a method of mixing the two components in advance and then adding them, or a method of adding both components individually. In the present invention, if necessary, aggregates (fine aggregate, coarse aggregate), general water reducing agents, AE agents, early strengthening agents,
A retarder or the like may be added. Examples of fine aggregate include river sand, sea sand, crushed sand, slag sand, etc., and examples of coarse aggregate include river gravel, crushed stone, crushed slag, lightweight aggregate, etc. . The cement mixture thus obtained (ie concrete, mortar or cement paste) is then cast at a low temperature of below 5°C. Conventionally, a method of improving water reduction performance by using a high performance water reducing agent such as a naphthalene sulfonate formalin condensate or a melamine sulfonate formalin condensate together with an olefin-maleic anhydride copolymer salt has been known (especially Publication No. 55-51863, same
56-12268). However, in the present invention, by using both of these components in a specific ratio and casting under low salt conditions, the effect of improving water reduction performance is further improved, and moreover, it exhibits excellent performance in both initial strength and long-term strength. A hardened cement product can be obtained.
In particular, excellent improvement effects can be obtained in the case of concrete mixtures. The present invention will be explained in more detail with reference to Examples below. Note that parts and percentages in Examples and Comparative Examples are based on weight unless otherwise specified. Reference Example 1 1 A mixture of 98 parts of maleic anhydride, 110 parts of the C5 olefin mixture shown in Table 1, 4 parts of benzoyl peroxide, and 400 parts of benzene was heated in an autoclave under a nitrogen atmosphere at 70 to 75°C for 8 hours. The mixture was heated and stirred to react. After the polymerization reaction was completed, the precipitated copolymer was collected by filtration and dried. 89 parts of a C5-chain olefin-maleic anhydride copolymer was obtained. 84 parts of this copolymer and 400 parts of a 10% aqueous sodium hydroxide solution were heated and stirred at 80 to 90°C, and C5
An aqueous solution of sodium salt of -chain olefin-maleic anhydride copolymer was obtained. Table 1 iso-pentane 15.57% n-pentane 15.44% 2-methylbutene-1 42.06% pentene-1 26.88% isoprene 0.05% Reference example 2 Replacement of olefin in reference example 1 as shown in Table 2
Except that 75 parts of C5-linear olefin mixture was used.
By the same operation as in Reference Example 1, 110 parts of a copolymer was obtained. A mixture of 84 parts of this copolymer and 400 parts of a 10% aqueous sodium hydroxide solution was heated and stirred at 80 to 90°C to obtain an aqueous solution of sodium salt of C5-chain olefin-maleic anhydride copolymer. . Table 2 n-pentane 2.46% 2-methylbutene-1 12.60% trans-pentene-2 35.05% cis-pentene-2 15.93% 2-methylbutene-2 31.70% Pentene-1 2.26% Reference example 3 C5 olefin of reference example 1 67 parts of a copolymer was obtained in the same manner as in Reference Example 1, except that 60 parts of butene-1 was used instead of the mixture. A mixture of 38.5 parts of this copolymer and 200 parts of a 10% aqueous sodium hydroxide solution was heated and stirred at 80 to 90°C to obtain an aqueous solution of the sodium salt of butene-1-maleic anhydride copolymer. Reference Example 4 Put 98 parts of maleic anhydride, 300 parts of methyl ethyl ketone, 84 parts of hexene-1, and 4 parts of azobisisobutyronitrile into a separable flask equipped with a reflux tube, and stir at 65 to 70°C under a nitrogen atmosphere. I reacted while doing so. After reacting for 10 hours, the system was cooled to room temperature, and cold methanol was added to precipitate the polymer. After collecting by filtration, dry under reduced pressure to form a copolymer.
Obtained 108 copies. A mixture of 91 parts of the copolymer and 400 parts of a 10% aqueous sodium hydroxide solution was stirred at 80 to 90°C to obtain an aqueous solution of the sodium salt of hexene-1-maleic anhydride copolymer. Reference Example 5 100 parts of the C ₅ olefin-maleic anhydride copolymer obtained in Reference Example 1 was dissolved in 200 parts of methyl ethyl ketone, 5 parts of methyl alcohol was further added, and the mixture was stirred and reacted under reflux conditions for 8 hours. After the reaction,
After distilling off the methyl ethyl ketone from the system and drying the polymer, 10% aqueous sodium hydroxide solution 412
The degree of esterification was 12.8% by adding 100% of
(This means that 12.8% of the carbonyl groups in the copolymer form ester groups.) Sodium salt (water-soluble salt []) of partial methyl ester of _C5 olefin-maleic acid copolymer I got it. Examples 1 to 13 and Comparative Examples 1 to 4 Cement, water, aggregate, water reducing agent components, etc. were kneaded in a forced mixing mixer for 60 seconds at 5°C according to the following formulation, and the slump was measured according to JIS A1101. . Separate sampling was performed 90 minutes after the completion of kneading, and the samples were cured in water at a temperature of approximately 5°C, and after 3 days and
After 28 days, the compressive strength of each cured product was determined by JIS.
Measured according to A1108. The results are shown in Table 3. Blended cement: Ordinary Portland cement manufactured by Chichibu Corporation
400Kg/m ^3Coarse aggregate: Maximum dimension 20mm from Sagami 1140Kg/m ^3Fine aggregate: River sand from Oigawa River 691Kg/m ^3Water : 160Kg/m ^3Water reducer component: Specified amount for cement

[Table] From this result, it can be seen that the combined use of components (A) and (B) improves water reduction performance and improves both initial strength and long-term strength. Furthermore, it can be seen that the present invention exhibits superior effects when compared to the known technique in which gluconic acid, which is a typical example of a setting retardant, is used in combination with component (A).

Claims (1)

[Claims] 1. When producing a cement cured product by kneading cement, water reducing agent components, water and desired compounding agents and pouring at a temperature of 5°C or less, high performance water reducing agent (A) and a carbon number of 4 to 4 are used as water reducing agent components. The water-soluble salt (B) of the copolymer of chain olefin and ethylenically unsaturated dicarboxylic acid anhydride in No. 6 was mixed with 95 to 70% by weight of component (A) and 5 to 30% by weight of component (B).
A method for producing a cured cement product at a low temperature, characterized by using the combined products in a proportion of % by weight.