JP2004284951A - Centrifugal forming aid and cement composition using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal forming aid comprising a high-performance water reducer composition used for mortar and concrete used for civil engineering constructions, buildings, structures, and concrete products, which increases a water-reducing ratio, decreases a slump loss with time, improves dehydrating and compaction, and gives high-strength concrete and high-strength centrifugally formed products having a good workability, and to provide a cement composition using it. <P>SOLUTION: The centrifugal forming aid comprises a high-performance water reducer composition comprising a high-performance water reducer and an alkali metal sulfate, where 2-100 pts.wt. of the alkali metal sulfate is mixed with 100 pts.wt. of the solid part of the high-performance water reducer. The cement composition is formed by containing cement and the centrifugal forming aid, where 0.6-4.0 pts.wt. of the centrifugal forming aid on the basis of the high-performance water reducer is added to 100 pts.wt. of cement. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mortar used for civil engineering construction structures and concrete secondary products, a centrifugal force forming aid comprising a high-performance water reducing agent composition for concrete, and a cement composition using the same. Centrifugal molding aid comprising a high-performance water-reducing agent composition having improved mortar flow over time (i.e., the amount of aging decrease) and concrete slump over time, and improved centrifugal formability, and And a cement composition using the same.

  Polyalkyl allyl sulfonate type, melamine formalin resin sulfonate type, and aromatic amino sulfonate type high performance water reducing agent are lignin sulfonate type water reducing agent, polyol type water reducing agent, oxycarboxylate type water reducing agent Compared with general water reducing agents such as water repellents, the water reduction rate is large, and even if blended in a relatively large amount, it does not cause abnormal setting or excessive delay of cement and has low air entrainment. Used for the production of high-strength concrete and high-strength concrete products.

  However, these high-performance water reducing agents have a large amount of slump change over time (that is, a decrease with time). Therefore, when the slump is kneaded in a ready-mixed plant and transported by an agitator truck or truck, the slump is stable. Cannot be provided, and in extreme cases, the amount of slump changes with time is so large that it is impossible to discharge the slump from the agitator when casting.

  Furthermore, the water reduction rate of the high-performance water reducing agent reached a peak at about 2 parts by weight of solids relative to 100 parts by weight of cement, indicating a limit.

  In addition, although these high-performance water reducing agents have a large dispersing force, they do not lower the surface tension of water, so that they inhibit the dehydration during centrifugal force forming and deteriorate concrete tightness. Then, a soft paste layer is formed on the inner surface of the centrifugal force molding, and the paste layer undulates or sags, so that a smooth hollow section cannot be obtained. In the case of piles, such a phenomenon causes problems such as the auger not being able to enter or being caught in the middle when the pile is constructed by the Nakahori method, resulting in the problem that it is impossible to finish with a fume pipe etc. Will have.

  In particular, in the case of mortar or concrete in which these high performance water reducing agents and fine powders such as silica fume are used in combination for the purpose of obtaining high strength, the amount of change over time (that is, the amount of decrease over time) of slump and the like becomes extremely large, and the However, when the water-cement ratio is 25% by weight or less, there is also a problem that concrete may not be compacted at all.

Regarding the reduction of the amount of slump change with time and the improvement of centrifugal force formability of these high-performance water reducing agents, the present inventors have proposed to use a polyvalent oxycarboxylate salt among retarders (see Patent Document 1). ).
However, in this case, there are problems such as an increase in the unit water amount to obtain the same slump, resulting in a reduction in the water reduction rate of the high-performance water reducing agent, and a problem such as a marked delay in the curing speed at low temperatures. Was.

Japanese Patent Publication No. 01-037343

  The present inventor, in order to solve the above problems, as a result of intensive research, as a result, by mixing a specific amount of a specific component conventionally known as a setting accelerator of cement with a high-performance water reducing agent, the setting speed is reduced. It has no effect (when the same amount of high-performance water reducing agent is used, the strength per day is accelerated and the strength is high). The inventors have found that the dehydration property is improved, and have completed the present invention.

  That is, the present invention is a centrifugal force forming aid comprising a high-performance water reducing agent composition comprising a high-performance water reducing agent and an alkali metal sulfate, wherein the alkali metal sulfate is a high-performance water reducing agent. A centrifugal molding aid that is 2 to 100 parts by weight, based on 100 parts by weight of solids, a cement composition comprising cement and the centrifugal molding aid; The cement composition wherein the auxiliary agent is 0.6 to 4.0 parts by weight based on 100 parts by weight of cement, based on the high-performance water reducing agent.

  Hereinafter, the present invention will be described in detail.

  In the present invention, a high-performance water reducing agent and a sulfate of an alkali metal (hereinafter, referred to as alkali sulfate) are blended, and the alkali metal indicates sodium, potassium, or lithium.

The high-performance water reducing agent used in the present invention is a water reducing agent having a large water reduction rate that does not cause air entrainment or excessive setting delay even when used in a relatively large amount, and also does not cause abnormal setting. Examples include those containing any one of allyl sulfonate, melamine formalin resin sulfonate, and aromatic amino sulfonate as main components.
Examples of commercially available polyalkylallyl sulfonate-based high-performance water reducing agents include methyl naphthalene sulfonic acid formalin condensate, naphthalene sulfonic acid formalin condensate, anthracene sulfonic acid formalin condensate, and naphthalene sulfonic acid and lignin. Salts such as co-condensates of sulfonic acids may be mentioned. Commercially available products include “FT-500” (trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.) and “Mighty 100”, “Mighty 150”, and “Mighty 2000” manufactured by Kao Corporation. Series, such as "Cell Flow 110P" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., "Pole Fine 510N" manufactured by Takemoto Yushi Co., Ltd., and "Sunflow PS", "Sunflow HS700" manufactured by Sunflow, etc. Is a representative, aromatic aminosulfonate-based high-performance water reducing agent As a high performance water reducing agent based on melamine formalin resin sulfonate, "FT-3S" manufactured by Denka Grace, product manufactured by Showa Denko KK The names "Mole Master 10" and "Mole Master 20" are exemplified.
These may be used alone, or two or more of them may be arbitrarily mixed and used.
In particular, a melamine formalin resin sulfonate type and a mixed type of water reducing agents having greatly different types such as a polyalkylallyl sulfonate type or an aromatic amino sulfonate type are preferable for reducing the amount of change with time of the slump. In some cases, results are shown.

  Alkali sulfate is commonly used as an industrial raw material, and is used in combination with a high-performance water reducing agent to increase the mortar flow and concrete slump to improve the water reduction rate and to change the mortar flow and slump with time ( That is, it has the effect of reducing the amount of aging (ie, the amount of aging) and the amount of change with time of the slump (ie, the amount of aging) and promoting the initial strength. In addition, the centrifugal force formability is also improved.

Alkali sulphate increases the slump of concrete, improves water reduction and increases strength, and is also effective in improving the formability of centrifugal force, but is effective in reducing the amount of slump in concrete over time. Is small.
However, the result is suitable for manufacturing a high-strength concrete secondary product in which the working time is about 30 minutes.
Further, the alkali sulfate can reduce the amount of change in the slump with time (that is, the amount of decrease with time) by using in combination with sulfites that reduce the amount of change in the slump with time other than the alkali sulfate (that is, the amount of decrease with time).

  The appropriate mixing ratio of the high-performance water reducing agent and the alkali sulfate varies depending on the amount of the high-performance water reducing agent in the cement. Is preferred. It is more preferably in the range of 5 to 70 parts by weight, and even more preferably in the range of 10 to 50 parts by weight. If the amount is less than 2 parts by weight, the effect of increasing the water reduction rate and the effect of reducing the amount of slump change with time are reduced, and the effect of promoting the initial strength is also reduced. On the other hand, when the amount exceeds 100 parts by weight, the effect of accelerating the setting and hardening becomes too strong, and the effect of improving the water reduction rate and reducing the amount of change with time of the slump decreases. Further, the elongation of the long-term strength is also decreased, which is not preferable. Further, the proper mixing ratio of the high-performance water reducing agent and the alkali sulfate has the same effect on the dewatering property at the time of centrifugal molding, the tightness of concrete, and the thickness of the paste layer formed on the inner surface of the centrifugal molding.

  The high-performance water reducing agent composition of the present invention comprises a high-performance water reducing agent and an alkali sulfate. The amount used is 100 parts by weight of the solid content of the high-performance water reducing agent, 2 to 100 parts by weight of alkali sulfate is blended, 100 parts by weight of cement, 0.6 parts by weight of the high-performance water reducing agent To 4.0 parts by weight, preferably 0.8 to 3.0 parts by weight, more preferably 1.0 to 2.0 parts by weight. When the amount of the high-performance water reducing agent is less than 0.6 parts by weight, the effect of reducing the amount of change with time of the slump cannot be exerted, so that it is not preferable. And it is uneconomical.

  The cement used in the present invention is usually a variety of Portland cements, such as high strength, ultra-high strength, white, moderate heat, and low heat, and various kinds of mixture obtained by blending blast furnace slag, fly ash, or silica powder with these portland cements. Cement, slag-based cement in which slag is blended to a JIS standard value or more, and the like can be given.

In addition, anhydrous gypsum, high-strength admixture containing gypsum as a main component, components that exhibit high strength such as fly ash fume, silica fume, and fine powder slag, and cement expanding materials are also used in these cements. You.
In particular, when a high-performance water reducing agent and fine powder such as fly ash fume and silica fume are used, the amount of change over time (ie, the amount of decrease over time) of slump and the like becomes extremely large. In the present invention, fine powder such as silica fume is used. When the compounding amount of the compound is 15 parts by weight or less with respect to 100 parts by weight of cement, a sufficient working time can be obtained (the amount of change with time is small).

The high-performance water reducing agent composition of the present invention is compounded when kneading mortar and concrete, and the kneading method may be a commonly used method, and the compounding method is not particularly limited. is not.
Therefore, the respective components may be separately compounded irrespective of whether they are solid or liquid.When a powdery high-performance water reducing agent is used, the components may be mixed in a powder state in advance and mixed. Alkali sulfate may be dissolved and blended in the high-performance water reducing agent, or it may be diluted with water and blended in a mixer.

  By using the centrifugal molding aid comprising the high-performance water-reducing agent composition of the present invention and the cement composition using the same, further improvement of water reduction rate, which is a problem of the conventional high-performance water-reducing agent, and aging of slump The amount of change (that is, the amount of decrease with time) can be reduced, and the dewatering property and tightness at the time of centrifugal force forming can be improved, so that it is possible to manufacture high-strength concrete and high-strength centrifugal force forming products with good workability.

  Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

<Material used>
"Types of cement"
OPC1: Ordinary Portland cement, manufactured by Denki Kagaku Kogyo KK, specific gravity 3.16
OPC2: 5% by weight of ordinary Portland cement replaced with anhydrous gypsum OPC3: 5% by weight of ordinary Portland cement replaced with silica fume OPC3-1: 2% by weight of ordinary Portland cement replaced with silica fume OPC3-2: 8% by weight of ordinary Portland cement replaced with silica fume OPC3-3: 11% by weight of ordinary Portland cement replaced with silica fume OPC3-4: 15% by weight of ordinary Portland cement with silica fume OPC3-5: 18% by weight of ordinary Portland cement replaced by silica fume BFS1: Blast furnace slag cement, blast furnace slag mixing ratio: 50% by weight
BFS2: 5% by weight of BFS1 substituted with anhydrous gypsum BFS3: 5% by weight of BFS1 substituted with silica fume Anhydrite: Natural type II anhydrous gypsum, specific surface area 6,000 cm ² / g, specific gravity 2.90
Silica fume: Elchem, specific gravity 2.14
Blast furnace slag: specific surface area 6,000cm ^{2 /} g
"aggregate"
River sand: Himekawa river sand, Niigata prefecture, specific gravity 2.62
Crushed stone: Crushed stone from Himekawa, Niigata Prefecture, specific gravity 2.64
"Water": groundwater, specific gravity 1.00
`` High performance water reducing agent ''
High performance water reducing agent A: powdered, Daiichi Kogyo Seiyaku Co., Ltd. powdered, high performance water reducing agent based on polyalkylallyl sulfonate B: Showa Denko Co., Ltd.
Sulfites a: potassium sulfite, industrial sulfite b: sodium bisulfite, industrial sulfite c: potassium bisulfite, industrial sulfite d: sodium sulfite, industrial sulfite e: calcium sulfite, reagent primary sulfite f: sodium pyrosulfate, industrial sulfites g: potassium pyrosulfite, industrial sulfites h: sodium pyrosulfite, industrial sulfites i: potassium pyrosulfite, industrial sulfites j: potassium sulfate, industrial sulfites k : Sodium sulfate, industrial sulfites l: sodium bisulfate, industrial sulfites m: potassium bisulfate, industrial sulfites n: lithium sulfate, reagent

The type of cement is OPC1, and 100 parts by weight of OPC1, 200 parts by weight of river sand, and 25 parts by weight of water are used. By changing the amount of sulfites while keeping the amount of the high-performance water reducing agent constant, The mortar flow in a stationary state, its change with time, and the compressive strength of 1 day and 28 days old were measured.
The high-performance water reducing agent and the sulfites were used in parts by weight with respect to 100 parts by weight of OPC1, and were previously mixed with the cement and kneaded. Table 1 shows the results.
Mortar flow, after kneading according to JIS R 5201, the flow when pulling out the flow cone on a glass plate using a flow cone of JIS R 5201, immediately after kneading, 60 minutes after standing still, 90 Measured after minutes. The compressive strength was also measured by molding a mortar in a 4 × 4 × 16 cm mold according to JIS R 5201 and curing under a standard curing condition.

  The procedure was performed in the same manner as in Example 1 except that the amounts of the high-performance water reducing agent and the sulfites were fixed and the types of the sulfites were changed. Table 2 shows the results.

  The procedure was performed in the same manner as in Example 1 except that the type and amount of sulfites were kept constant and the amount of the high-performance water reducing agent was changed. Table 3 shows the results.

  In the comparison between Experiment No. 1-1 and Experiment No. 1-2 to Experiment No. 1-11 in Table 1, in this example, 2 to 100 parts by weight of the sulfite was added to 100 parts by weight of the high-performance water reducing agent. It is shown that the improvement of the mortar flow and the amount of change with time of the flow, particularly the (flow value immediately after kneading—the flow value after 90 minutes) are improved in the range of, and particularly, the mortar flow is 5 to 5 It is shown that 70 parts by weight is preferable and 10 to 50 parts by weight is more preferable. Further, in the examples of the present invention of Experiment No. 1-39 to Experiment No. 1-43, when the amount of the high-performance water reducing agent increases, the amount of mortar flow change with time decreases, and 0.6 parts by weight or more is required for 100 parts by weight of cement. It is more preferably 0.8 part by weight or more, further preferably 1.0 part by weight, the upper limit is 2.0 parts by weight from the comprehensive viewpoint of the effect of increasing the mortar flow, the amount of change with time, initial, long-term strength development, and economy. Is more preferred.

Using the high performance water reducing agent compositions of Experiment No. 1-1 and Experiment No. 1-2 to Experiment No. 1-11 in Table 1, concrete tests were carried out using the concrete mix shown in Table 4 and left standing. And the compressive strength of the specimens of 1 day and 28 days in standard curing with a specimen of φ10 × 20 cm were measured. The high-performance water reducing agent composition of the present invention is a part by weight based on 100 parts by weight of OPC1. Table 5 shows the results.
The concrete was mixed by using a planetary type 100-liter capacity forced mixing mixer and mixing 30 liters of concrete.
The order of charging the materials was crushed stone, sand, and OPC1 (the high-performance water reducing agent composition of the present invention was lightly mixed with OPC1 in advance), kneaded for 10 seconds, then mixed with water and kneaded for 90 seconds. Was.
At this time, when the slump increased due to the sulfites, the change in the slump with time was measured without reducing the unit water amount, and the 1-day and 28-day strengths after the standard curing with the mold packed with the compressive strength as it was were measured.
The materials used were the same as in Example 1. However, as the crushed stone, a crushed stone with a specific gravity of 2.65 from Himekawa was used.

In the test results shown in Table 5, the slump-up and the change with time of the slump of the present invention show the same tendency as the mortar flow of Example 1, and the water reduction rate is the same as in Experiment Nos. In the case of the slump equivalent to the comparative example of 1, the unit water amount of about 14 kg / m ³ (the unit water amount fluctuates by 1 kg / m ³ for 1 cm of slump) is reduced, and the strength is 7 N / mm ² . Increased.

Change the type of cement. For each 100 parts by weight of cement, 1.2 (100) parts by weight of high-performance water reducing agent A, 0.3 (25) parts by weight of sodium bisulfite of sulfite b, and sodium sulfate of sulfite k Was mixed with 0.2 (16.7) parts by weight or 0.2 (16.7) parts by weight of lithium sulfate of sulfites n, and the concrete was changed in the same manner as in Example 4 in the case where the type of cement and the type of admixture were changed. The mixture was kneaded, and similarly, the change with time of the slump and the compressive strength were measured. Table 6 shows the concrete composition. The values in parentheses are (parts by weight) of sulfites based on 100 parts by weight of the high-performance water reducing agent.
For the comparative example, only the high-performance water reducing agent A was blended, and the amount of the water reducing agent was arbitrarily increased so as not to change the water-cement ratio in order to match the concrete slump of the present invention using sodium bisulfite or the like. . Table 7 shows the test results.

In Table 7, in the system using sodium bisulfite in combination with the examples of the present invention, the change with time of the slump is reduced and the initial and long-term strength is increased regardless of the type of the cement and the type of the admixture.
In addition, the same slump can be obtained with sodium sulfate or lithium sulfate in a smaller amount than sodium bisulfite, that is, the water reduction rate is large. Although a high value is obtained for both the initial long-term strength, the effect of reducing the change over time of the slump is small.

Comparative Examples of Experiment Nos. 3-1 to No. 3-3 of Example 5 and Experiments No. 3-7 to No. 3-9, Experiments No. 3-13 to No. 3-15, For the concretes of Experiment Nos. 3-19 to 3-12, a centrifugal force forming specimen having an outer diameter of 20 cm, a length of 30 cm, and a thickness of 5 cm was prepared. After holding at a temperature of 3 hours and a temperature of 75 ° C. for 4 hours, the compressive strength of one-year-old material naturally cooled in a curing tank was measured.
The centrifugal force forming test specimen was rotated at a low speed of 3 G for 3 minutes, at a medium speed of 8 G for 4 minutes, and at a high speed of 30 G for 3 minutes while the amount of concrete charged was constant at 18 kg.
The evaluation of the moldability was carried out by measuring the amount of generated sludge with a measuring cylinder, and measuring the thickness of a soft paste that does not tighten the inner surface of the centrifugal molding specimen after molding. Table 8 shows the results.
In the centrifugal force forming, the concrete was kneaded and mixed within 15 minutes after the kneading according to the actual conditions of the working process such as a pile factory. At this time, concrete slumps of OPC3 and BFS3 having large slump loss and containing sodium sulfate were approximately 4 to 6 cm.

Table 8 shows that, in the present invention, regardless of the presence or absence of the admixture and the type of the admixture, the centrifugal force formability is improved, the amount of dehydration is increased, and the tightening is improved, and the generation of a soft paste layer on the inner surface is eliminated. It is shown that the strength is improved.
Further, it is shown that sodium sulfate and lithium sulfate exert more excellent effects on centrifugal force formability than sodium bisulfite.

In the concrete compounding of OPC3 in Table 6 of Example 6, the cement type was changed to 100 parts by weight of cement using OPC3, OPC3-1, OPC3-2, OPC3-3, OPC3-4, and OPC3-5. Then, 1.2 (100) parts by weight of the high-performance water reducing agent A and 0.3 (25) parts by weight of potassium sulfite were mixed, and concrete was kneaded in the same manner as in Example 6, and the amount of change with time of the slump was measured.
At this time, the slump variation due to the blending amount of silica fume was ignored, and the slump was not adjusted. Table 9 shows the results.

  As shown in a comparison between Experiment No. 3-1 and Experiment No. 3-3 in Table 7, when silica fume was blended, the amount of change with time of the slump was remarkably large. In the examples, it is shown that it is remarkably improved, and the improvement effect is particularly large at a compounding amount of 15 parts by weight or less.

Claims (4)

  A centrifugal molding aid comprising a high-performance water reducing agent composition obtained by blending a high-performance water reducing agent and an alkali metal sulfate.   The centrifugal force forming aid according to claim 1, wherein the alkali metal sulfate is 2 to 100 parts by weight based on 100 parts by weight of the solid content of the high-performance water reducing agent.   A cement composition comprising cement and the centrifugal force forming aid according to claim 1 or 2.   The centrifugal force forming aid according to claim 1 or 2 is 0.6 to 4.0 parts by weight based on 100 parts by weight of cement, based on the high-performance water reducing agent. Cement composition.