JPH0637319B2 - Method for curing cement composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for curing a cement composition.

An object of the present invention is to provide a cement composition with rapid hardening that exhibits high initial strength in an early stage, and high fluidity after kneading, which is convenient for construction, and further improve the adhesiveness of the splicing surface. It is to provide a method for curing a composition.

[Prior art]

In general, it takes at least one day for mold release when molding is performed using Portland cement,
In the construction and civil engineering industry, rapid hardening cement is required in order to shorten the cycle of formwork and promote construction.

As a quick-setting agent that hardens Portland cement,
Various things are known conventionally.

For example, alkali carbonate, alkali aluminate, C ₁
Calcium aluminate (hereinafter referred to as CA) such as A ₁ , C ₁₂ A ₇ , C ₁ A ₂ , C ₁₁ A ₇ and CaF ₂ , alumina cement, C ₁₂ A ₇
Calcium sulfoaluminate (hereinafter referred to as CSA), which is obtained by mixing gypsum with, has been proposed.
(However, the C is CaO, A is. Shows the Al ₂ O ₃₎ They are usually 2-5% by weight relative to Portland cement, 10 wt% amount corresponding at most been used blended.

On the other hand, as an admixture that improves the fluidity of cement, those containing lignin sulfonate, melamine formalin condensate sulfonate, polyalkylallyl sulfonate, carboxylate, etc. as the main ingredients, also have a long pot life. As a curing retarder for extending the viscosity, oxyacid salts, gluconates, etc. have been proposed.

[Problems to be solved by the invention]

Portland cement added with a quick-setting agent starts hydration immediately when water is added and kneaded, and shows rapid hardening, but on the other hand, the fluidity is lost in an extremely short time and the kneaded product must be poured into the mold. There is a problem in work such as making it difficult.

If the addition amount of the quick-setting agent is reduced to improve the fluidity,
The initial strength is delayed and the rapid hardening function becomes insufficient.

Even if the cement containing the quick-setting agent is used in combination with polyalkylallyl sulfonate, lignin sulfonate, carboxylate, etc. in order to improve the fluidity, the fluidity is not sufficiently improved. The onset of strength may be delayed. Even if oxyacid salts and gluconates are used, there are similar problems.

In this way, conventionally known quick-setting agents, superplasticizers,
By simply combining a curing retarder, etc., it imparts rapid hardening properties and high fluidity after kneading to the cement composition,
Moreover, it is difficult to improve the adhesiveness of the splice surface.

[Means for solving problems]

The present inventors have conducted extensive studies in order to improve such a problem, and combine the specific amounts of potassium carbonate and melamine formalin condensate sulfonate (hereinafter, referred to as MFS) with the centescent composition. By,
Surprisingly, it is possible to have both rapid hardness and fluidity, which are contradictory properties, and to improve the adhesiveness of the splicing surface, and for cement compositions containing aggregates such as mortar and concrete. The present invention was completed by discovering that by blending specific amounts of potassium carbonate, MFS, and a water-soluble polymer, breathing can be reduced, fluidity can be maintained, and rapid hardening and adhesiveness of a joint surface can be improved. did.

That is, the first invention is "when adding water to a cement composition containing potassium carbonate and kneading and hardening it, 7.5 to 25 parts by weight of potassium carbonate, melamine formalin condensate sulfonate per 100 parts by weight of cement. 0.5-10
A method for hardening a cement composition, which comprises adding water to a composition obtained by mixing 1 part by weight and kneading, and the second invention is "adding and kneading water to a cement composition containing potassium carbonate. In order to harden the mixture, 7.5 to 25 parts by weight of potassium carbonate, 0.5 to 10 parts by weight of melamine formalin condensate sulfonate and 0.05 to 5 parts by weight of water-soluble polymer are added to 100 parts by weight of cement. Each of the main points is "a method for hardening a cement composition, which comprises adding water to the obtained composition and kneading." In the following description, "part" means "part by weight".

Hereinafter, the details of the present invention will be described.

The cement of the present invention includes ordinary Portland cement, early-strength cement, ultra-early-strength cement, medium heat Portland cement, sulfate-resistant Portland cement and other Portland cement, blast furnace cement, silica cement, fly ash cement and other mixed cements. And so on.

In the method of the present invention, cement includes river sand as an aggregate,
Various lightweight aggregates such as mountain sand, sea sand, silica stone, and crushed stone can be added.

In the method of the present invention, potassium carbonate is used for rapidly hardening the cement composition, and the addition amount of potassium carbonate is 7.5 to 25 parts, preferably 10 parts per 100 parts of cement.
A good range is 20 parts.

If the amount added is less than 7.5 parts, rapid hardening cannot be obtained, the initial strength is small, and the fluidity is not improved. Further, even if added in excess of 25 parts, the effect of improving the rapid hardening and fluidity does not improve so much and the long-term strength also decreases.

When 10 parts or more of potassium carbonate is added per 100 parts of cement, a quick-setting agent other than potassium carbonate, such as sodium carbonate, water-soluble alkali aluminate salts or alkali silicate salts, CAs, CSAs, etc. It is also possible to use one or more of them in combination so long as the fluidity is not deteriorated.

In the method of the present invention, MFS is added to improve the fluidity of a cement composition containing potassium carbonate, but is usually used as an admixture for cement compositions (as a water reducing agent or a cement dispersant). Things can be used.

The amount of MFS added is 0.5 to 10 parts, preferably 1 to 5 parts per 100 parts of cement.

If the addition amount is less than 0.5 part, the fluidity is not improved, while
If it exceeds 10 parts, not only the fluidity is not improved so much, but also the initial strength is delayed and the long-term strength is reduced.

Next, in the second invention, a water-soluble polymer is further added to the cement composition in addition to potassium carbonate and MFS. By adding a water-soluble polymer, while preventing the occurrence of breathing and laitance when the water ratio to the cement is increased, to improve the fluidity of the cement composition containing a large amount of aggregate, and the adhesion of the joint surface You can

Examples of the water-soluble polymer used in the present invention include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, polyvinyl alcohol, polyacrylic acid alkali salt, polyacrylamide, polyethylene oxide and the like.

The amount of water-soluble polymer added is 0.05 to 100 parts of cement.
The range is 5 parts, preferably 0.1 to 2 parts.

If the addition amount is less than 0.05 part, the effect of improving the fluidity and the adhesive strength of the splice surface is small. On the other hand, when it exceeds 5 parts, the fluidity and the adhesiveness of the splice surface are good, but the initial strength and long-term strength are not well expressed.

Even in a cement composition containing potassium carbonate, the temperature of the material is
If it is lower than 15 ° C, the rate of cement hydration is hard to be accelerated, so
Cement slurry, mortar, obtained by kneading a cement composition containing additives and, if necessary, aggregate with water
The temperature of the material such as concrete is 15 ℃ or higher, preferably
It is good to keep at 20 ℃ or higher. In order to maintain the temperature of the materials and hardened material after kneading at 15 ° C or higher, it is possible to heat the materials used such as cement and aggregate and the water for kneading, attach a heater to the formwork, and heat with hot water or steam. It is advisable to use a structural formwork to keep it warm.

The cement composition used in the method of the present invention includes those preliminarily manufactured with a predetermined composition and those prepared with a predetermined composition at the time of use at a construction site.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to the present invention, to a cement composition; suppresses bleeding of a kneaded material; imparts rapid hardening that exhibits high initial strength at an early stage and high fluidity after kneading, which is convenient for construction; It is possible to provide a curing method capable of obtaining good long-term strength.

Hereinafter, the present invention will be described with reference to Examples, Comparative Examples and Reference Examples.

〔Example〕

 Examples: 1-19. Comparative Examples: 1 to 15, Reference Examples: 1 to 10; Materials used are as follows.

(1) Cement: ordinary Portland cement, (2) sand: FM value 2.8; (3) gravel: crushed stone (maximum diameter: 25 mm), (4) quick setting agent: a) potassium carbonate, for comparison, b ) Sodium aluminate, c) CSA, ("Natomic" manufactured by Denki Kagaku Kogyo Co., Ltd.). d) Mixture of C ₁₁ A ₇ · CaF ₂ and K ₂ CO ₃ , (mixing ratio… C ₁₁ A ₇ · CaF ₂ : K ₂ CO ₃ = 8: 2 (weight basis)) e) Sodium carbonate, ( 5) Superplasticizer: h) MFS, (“SMF-PD” manufactured by Nissan Chemical Industries, Ltd.). For comparison, i) lignin sulfonate, ("Pozoris No. 8" manufactured by Nisso Master Builders Co., Ltd.). j) Polyalkylallyl sulfonate, ("Madinone 100" manufactured by Yamamune Chemical Co., Ltd.). k) Carboxylate, ("Palic", manufactured by Fujisawa Pharmaceutical Co., Ltd.). (6) Water-soluble polymer: p) Methylcellulose, (Shin-Etsu Chemical Co., Ltd., "hi Metrows"). q) Hydroxyethyl cellulose, ("Natrosol" manufactured by Hoechst Synthesis Co., Ltd.). r) Ethyl hydroxyethyl cellulose, (Nissho Verol Co., Ltd., "Vermocole"). s) Sodium polyacrylate, t) Polyacrylamide, u) Polyvinyl alcohol, [a), b) ... u) above correspond to those described in Table-2 (1) and (2). ] Table 1 shows the basic composition, water mixture ratio and physical properties of the cement composition used.

To the cement composition shown in Table-1, various cement compositions obtained by blending various additives in the proportions shown in Table-2 are shown in Table-1.
Water is added at the water mixing ratio (W / C) shown in and kneaded, and the results of tests on the following items are shown in Table-2 (1) and (2).

1) Liquidity. Slump: Conforms to JIS A1101. Flow table: Conforms to JIS R5201. Flow test: The sample range immediately after kneading was filled in a rigid polyvinyl chloride cylindrical frame (inner diameter 50 mm, height 100 mm) placed on a glass plate and the frame was pulled up vertically. (A measured value of 50 mm indicates no flow). 2) Presence or absence of breathing. ◎… None, ○ …… Almost no, △… Some, ▲… Yes. 3) Proctor penetration test: Shows the measured value (1bs.) At 60 minutes after kneading the sample.

4) Compressive strength: Specimen (100 mmφ × 200 mm). (When the measured value of Proctor penetration test is 30 or less, the measurement of initial strength (rise of compressive strength) is omitted.) 5) Adhesive strength of piecing surface: 1 after piecing with a Kenken type tensile tester. The adhesive strength of the test piece (40 × 40 mm) that had passed the year was measured.

The effects of the addition of various superplasticizers alone are shown in Reference Examples: 1 to 4. When the fluidizing agent is added, the fluidity of the kneaded product is improved as compared with the case where the fluidizing agent is not added, but the compression strength is reduced. When MFS alone is added, the fluidity of the kneaded product is hardly improved.

Reference examples: 5 to 10 show the effects of the addition of various quick-setting agents alone.
There is a difference in the effect of accelerating the rise of initial strength depending on the type and amount of the quick-setting agent added. The fluidity of the kneaded product is significantly reduced in each case.

Even if a quick-setting agent other than potassium carbonate and various fluidizing agents are combined, the fluidity of the kneaded product is not improved.

Even if sodium aluminate is used as a quick-setting agent and a fluidizing agent is combined with it, the kneaded product does not show rapid hardening property, and the fluidity is lowered. (Comparative example: 1-4).

When a mixture of CSA or C ₁₁ A ₇ · CaF ₂ and potassium carbonate is used as a quick-setting agent, and a fluidizing agent is combined with each, when there is no breathing in the kneaded product and a rise in initial strength is observed. There is also a compressive strength (1d,
7d) is low and liquidity is not improved. (Comparative example:
5-8, 9-11). Similar to potassium carbonate, when sodium carbonate, which is a kind of alkali carbonate, is used as a quick-setting agent and this is combined with MFS, the kneaded product has no bleeding and the initial strength rises well, but the fluidity is not improved. (Comparative example: 12). When potassium carbonate is combined with lignin sulfonate or polyalkylallyl sulfonate as a fluidizing agent,
Although the fluidity of the kneaded product is improved, the initial strength is poorly raised and the kneaded product does not have a function as a rapid hardening cement composition.
(Comparative example: 13, 14). In the method of the present invention in which potassium carbonate and MFS are combined, both the initial strength of the kneaded product and the long-term strength are good, and the fluidity is improved so that the kneaded product can be poured into the mold and the workability is greatly improved. To do. Little breathing.
(Example: 1-6). If the amount of potassium carbonate added is less than 7.5 parts per 100 parts of cement, the fluidity of the kneaded product will not be improved even if MFS is combined, and the initial strength will not rise. (Comparative example: 15). The adhesive strength of the splicing surface was large at a low level of 10 to 25 kg / cm ² when potassium carbonate alone was added, while it was high at a high level of 25 to 30 kg / cm ^{2 by} the method of the present invention. It was stable.

When a water-soluble polymer is further used as an additive, the kneading of the kneaded material is not observed, and the fluidity is improved,
Good initial strength and long-term strength. The adhesive strength of the splice surface was further improved to 30-35 kg / cm ² .
(Example: 7-12). If 10 parts or more of potassium carbonate was added per 100 parts of cement, practical performance was obtained even when a small amount of a quick-setting agent other than potassium carbonate was used in combination. (Example: 13-
15). When the temperature of the kneaded product and the cured product is 15 ° C. or higher, the initial strength rises well and the rapid hardening function can be exhibited. (Example: 16-19). Example: 20. In the composition obtained by mixing the concrete material shown in Table 3 with the additive in the proportion shown in Table 2 (2), the water mixing ratio (W / W
C) was added with water and kneaded.

The slump of the kneaded product has a fluidity of 16 cm and can be poured into the mold, and the result of the test conducted according to Example 1 is that there is no breathing as shown in Table-2 (2) and the initial strength rises. And the long-term strength was also good. The adhesive strength of the splice surface was 30 to 35 kg / cm ² .

Example: 21. Additives were mixed in 1000 parts of cement, 3000 parts of sand, and 2000 parts of gravel in the proportions shown in Table 2 (2). Since the temperature was 5 ° C. or lower, 500 parts of water was heated to 75 ° C. and added, and kneaded. The temperature of the kneaded material was 27 ° C.

The slump of the kneaded material was 17 cm, and had a fluidity such that it could be poured into the mold. Since the temperature of the outside air was 3 ° C, a mold with a jacket was used, and it was poured into a mold kept warm through 30 ° C hot water.

As shown in Table-2 (2), there was no breathing, and the initial strength rise and the long-term strength were good. The adhesive strength of the splice surface was 35-40 kg / cm ² .

Claims (2)

[Claims] 1. When water is added to a cement composition containing potassium carbonate to knead and harden it, 7.5 to 25 parts by weight of potassium carbonate, 0.5 to 25 parts of melamine formalin condensate sulfonate per 100 parts by weight of cement are used. A method for hardening a cement composition, which comprises adding 10 parts by weight of water to a composition obtained and kneading. 2. When water is added to a cement composition containing potassium carbonate to knead and harden it, 7.5 to 25 parts by weight of potassium carbonate and 0.5 to 25 parts of melamine formalin condensate sulfonate per 100 parts by weight of cement are used. A method for hardening a cement composition, which comprises adding 10 parts by weight and 0.05 to 5 parts by weight of a water-soluble polymer to a composition obtained and kneading the mixture.