JP3297190B2 - Cement additive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a cement composition, ie, a cement additive used in cement paste, grout, mortar, concrete and the like. More specifically, the cement additive of the present invention has extremely high solubility in water, has high water-reducing properties, and suppresses material separation by imparting viscosity to the cement composition. In addition, the present invention provides a cement additive for improving the durability of a cement composition by adding the cement additive of the present invention.
It is another object of the present invention to provide a cement additive capable of further improving the setting retardation and air entrainment of a cement composition, and improving the fluidity and workability of the cement composition so as to suppress a decrease in fluidity with time.

[0002]

BACKGROUND ART In recent years, a method for producing concrete having excellent fluidity and separation resistance by using a cement dispersant such as a high-performance water reducing agent or a superplasticizer in combination with a cellulose derivative or an acrylate-based thickener has been recently developed. Japanese Unexamined Patent Publication (Kokai) No. 3-45544) or a method for producing concrete using a high-performance water reducing agent and a polysaccharide in combination (see Japanese Patent Application Laid-Open No. 5-9053), using a high-performance water reducing agent in combination with cellulose having an alkylsulfone group. (See Japanese Patent Application Laid-Open No. 5-85791). However, the thickeners and polysaccharides or celluloses having alkylsulfone groups used in these production methods have the disadvantage of decreasing the fluidity while increasing the viscosity of concrete and increasing the separation resistance. Therefore, in order to increase the fluidity of concrete, it was necessary to use a relatively large amount of cement dispersant in combination. In addition, the thickener has a performance problem in that it imparts undesired characteristics such as delaying the setting time of concrete and excessive entrainment of air.

Further, thickeners and polysaccharides are extremely difficult to dissolve in water, and when added to an aqueous solution of a cement dispersant, it is difficult to obtain a uniform solution by gelling. If it is impossible to supply a cement dispersant solution containing saccharides, or if the thickener is used in the form of a powder, there are drawbacks in handling, such as powdering and problems in measurement at the time of addition.

[0004] For this reason, cement addition which has both high water-reduction and moderate viscosity, does not have excessive air entrainment and setting delay in concrete, and has good solubility in water and is easy to handle. There is a strong demand for the development of agents.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies in order to solve the various problems in the prior art as described above, and as a result, have both high water-reduction and moderate viscosity, and The present invention has succeeded in providing a completely new cement additive having good solubility, easy handling, and no excessive air entrainment or setting retardation to the cement composition.

[0006] That is, the present invention provides a cement water reducing agent characterized by containing a sulfated polysaccharide having an average molecular weight of 5,000 to 200,000 obtained by sulfating a polysaccharide. The sulfated polysaccharide used in the cement additive according to the present invention is obtained by sulfating a polysaccharide. Examples of the polysaccharide include cellulose, cellulose ether (alkyl cellulose such as methyl cellulose, ethyl cellulose, etc .; hydroxyalkyl cellulose such as hydroxyethyl cellulose, hydroxypropyl cellulose; hydroxyethyl). Hydroxyalkylalkylcellulose such as methylcellulose, hydroxyethylethylcellulose and hydroxypropylmethylcellulose), curdlan, dextran, starch and xanthan gum.

In the present invention, the above-mentioned sulfated polysaccharide having an average molecular weight of 5,000 to 200,000 is preferably used, and has a sulfur content of 1.0 to 2 in elemental analysis.
0.0% is preferably used. In general, when the average molecular weight of the sulfated polysaccharide is less than 5,000, the viscosity is not sufficient, and when the average molecular weight is 200,000 or more, the cohesiveness tends to be strong, and the sulfur content is low. If the analysis value is less than 1.0%, the water reduction tends to be small, and the solubility in water tends to be low. If the sulfur content is 20.0% or more, the water reduction tends to be small. On the other hand, sulfated polysaccharides having an average molecular weight of 5,000 to 50,000 and a sulfur content of 0.01 to 1.0% by elemental analysis have low water-reducing effects and low solubility in water, It can be used as a cement additive to impart consistency to the cement composition, and it is particularly preferred to use it in combination with a conventional water reducing agent to supplement the water loss.

[0008] In the sulfation of the polysaccharide, a sulfating agent known as a sulfation means is used. Examples of the sulfating agent used include piperidine sulfate, sulfur trioxide pyridine complex, chlorosulfuric acid, sulfuric acid, and the like, but are not limited to these sulfating agents.

[0009] The cement additive of the present invention is roughly classified into a liquid or powdery one. The liquid form is, in principle, a solution in which a sulfated polysaccharide is dissolved in water, and the concentration can be appropriately determined according to the purpose of use and the method of use. In addition, the cement additive of the present invention may be blended with a known or commonly used water reducing agent or other additives as desired in order to impart variety. Examples of conventional water reducing agents include naphthalene sulfonate formalin condensate, melamine sulfonate formalin condensate, polycarboxylate, lignin sulfonate, oxycarboxylate, polysaccharide, polyalkyl sulfonate, aminoalkyl Sulfonate derivatives, aromatic sulfonic acid derivatives and the like can be illustrated, and examples of other additives include:
Examples thereof include an air amount adjusting agent, a drying shrinkage reducing agent, an accelerator, a retarder, a foaming agent, an antifoaming agent, a rust inhibitor, a quick-setting agent, and a water-soluble polymer substance.

The use amount of the cement additive of the present invention is appropriately determined according to the cement composition to be used, but is basically an amount that gives the cement composition the desired fluidity, water-reducing or viscous properties. It is. For example, usually, the sulfated polysaccharide contained in the cement additive of the present invention is added to the cement contained in the cement composition in an amount of 0.01 to 3.0% by weight in terms of solid content. Although it is an appropriate amount,
It is not limited to this range.

The cement additive of the present invention can be used not only for cement compositions such as generally used cement paste, mortar, grout and concrete, but also for the conventional cement additives such as thickeners and water-soluble polymer substances. 2 with the agent
Cement compositions that used a combination of seeds, such as high-fluidity concrete, superfluidity concrete, water-inseparable concrete, high-strength concrete, pumping concrete, poorly-mixed concrete, cement secondary products, centrifugal cement products, extrusion molding It can be used very effectively in the production of cement products, prepacked concrete, grout, plastering mortar, shotcrete, fiber reinforced concrete, self-leveling materials and the like.

[0012]

Production Examples The production examples of the sulfated polysaccharide used in the cement additive of the present invention and the average molecular weight and sulfur content thereof are shown below, and the cement additive of the present invention is exemplified by these production modes. It is not limited by.

Production Example 1 0.50 parts of cellulose (manufactured by Kanto Kagaku) is added to 40.0 parts of dehydrated and dried dimethyl sulfoxide (DMSO), and the mixture is stirred at room temperature for 60 minutes. After stirring, 1.0 part of piperidine sulfate is further added, and the mixture is reacted at 80 ° C. for 60 minutes. Next, DMSO was removed by vacuum distillation, acetone was added to the residue to collect a precipitate, which was washed with water, neutralized with NaHCO ₃ water, and added with 100 parts of distilled water. After the dialysis treatment, the sample is dried to obtain sulfated cellulose. Hereinafter, this is referred to as CLS.

Production Example 2 0.50 parts of xanthan gum (manufactured by Sansei Co., Ltd.) are added to 40.0 parts of dehydrated and dried pyridine, and the mixture is stirred at room temperature for 60 minutes. After stirring, 1.0 part of piperidine sulfate was further added.
The reaction is performed for 60 minutes while maintaining the temperature at 70 ° C. Next, pyridine was removed by distillation under reduced pressure, acetone was added to the residue, a precipitate was collected, washed with water, neutralized with NaHCO ₃ water, and 100 parts of distilled water was added. After the dialysis treatment, the sample is dried to obtain sulfated xanthan gum. Less than,
This is referred to as XGS.

Production Example 3 Cellulose ether (Hi-Met 90 manufactured by Shin-Etsu Chemical Co., Ltd.)
SH-30,000) was added to 40.0 parts of dehydrated and dried dimethyl sulfoxide (DMSO), and
Stir at room temperature for minutes. After stirring, 0.5 part of piperidine sulfate is further added, and the mixture is reacted at 80 ° C. for 60 minutes. Next, DMSO was removed by vacuum distillation, acetone was added to the residue to collect a precipitate, which was washed with water, neutralized with NaHCO ₃ water, and added with 100 parts of distilled water. After the dialysis treatment, the sample is dried to obtain a sulfated cellulose ether. Hereinafter, this is described as MC1.

Production Example 4 Cellulose ether (Hi-Met 90 manufactured by Shin-Etsu Chemical Co., Ltd.)
SH-30,000) was added to 40.0 parts of dehydrated and dried dimethyl sulfoxide (DMSO), and
Stir at room temperature for minutes. After stirring, 1.0 part of piperidine sulfate is further added, and the mixture is reacted at 80 ° C. for 60 minutes. Next, DMSO was removed by distillation under reduced pressure, acetone was added to the residue, and a precipitate was collected.
Neutralize with aHCO ₃ water and add 100 parts of distilled water. After the dialysis treatment, the sample is dried to obtain a sulfated cellulose ether. Hereinafter, this is described as MC2.

Production Example 5 Cellulose ether (Hi-Met 90 manufactured by Shin-Etsu Chemical Co., Ltd.)
(SH-15,000) was added to 40.0 parts of dehydrated and dried dimethyl sulfoxide (DMSO).
Stir at room temperature for minutes. After stirring, 2.0 parts of piperidine sulfate is further added, and the mixture is reacted at 70 ° C. for 60 minutes. Next, DMSO was removed by distillation under reduced pressure, acetone was added to the residue, a precipitate was collected, washed with water, neutralized with NaHCO ₃ water, and 100 parts of distilled water was added. After the dialysis treatment, the sample is dried to obtain a sulfated cellulose ether. Hereinafter, this is described as MC3.

Production Example 6 Cellulose ether (Hi-Met 90 manufactured by Shin-Etsu Chemical Co., Ltd.)
(SH-15,000) is added to 40.0 parts of dehydrated and dried pyridine, and the mixture is stirred at room temperature for 60 minutes. After stirring, 2.0 parts of chlorosulfuric acid is further added, and the mixture is reacted at 70 ° C. for 60 minutes. Next, pyridine was removed by distillation under reduced pressure, acetone was added to the residue, a precipitate was collected, washed with water, neutralized with NaHCO ₃ water, and 100 parts of distilled water was added. After the dialysis treatment, the sample is dried to obtain a sulfated cellulose ether. Hereinafter, this is described as MC4.

Production Example 7 0.50 part of curdlan (manufactured by Wako Pure Chemical Industries, Ltd.) is added to 40.0 parts of dehydrated and dried dimethyl sulfoxide (DMSO), and the mixture is stirred at room temperature for 2 hours. After stirring, 0.5 part of piperidine sulfate is further added, and the mixture is reacted for 60 minutes while maintaining the temperature at 85 ° C. Next, DMSO was removed by distillation under reduced pressure, acetone was added to the residue, a precipitate was collected, washed with water, neutralized with NaHCO ₃ water, and 100 parts of distilled water was added. After the dialysis treatment, the sample is dried to obtain a sulfated curdlan. Hereinafter, this is referred to as CA1.

Production Example 8 0.50 parts of curdlan are added to 40.0 parts of dehydrated and dried dimethyl sulfoxide (DMSO), and the mixture is stirred at room temperature for 2 hours. After stirring, 1.0 part of piperidine sulfuric acid is further added, and the mixture is reacted for 60 minutes while maintaining the temperature at 85 ° C. Next, DMSO was removed by distillation under reduced pressure, acetone was added to the residue to collect a precipitate, which was washed with water, neutralized with NaHCO ₃ water, and 100 parts of distilled water was added. After the dialysis treatment, the sample is dried to obtain a sulfated curdlan. Hereinafter, this is referred to as CA2.

Production Example 9 0.50 part of curdlan was added to 40.0 parts of dehydrated and dried dimethylsulfoxide (DMSO), and the mixture was stirred at room temperature for 2 hours. After stirring, 2.0 parts of piperidine sulfuric acid was added. The reaction was carried out for 60 minutes while keeping at 0 ° C. Next, DMSO was removed by distillation under reduced pressure, acetone was added to the residue to collect a precipitate, which was washed with water and then washed with NaHCO _3.
Neutralize with water and add 100 parts of distilled water. After permeation, the sample is dried to obtain sulfated curdlan. Hereinafter, this is referred to as CA3.

Production Example 10 Pyridine 40.0 obtained by dehydrating and drying 0.50 parts of curdlan
And stirring at room temperature for 2 hours. After stirring, 2.0 parts of chlorosulfuric acid was further added.
Let react for minutes. Next, pyridine was removed by distillation under reduced pressure, acetone was added to the residue, a precipitate was collected, washed with water, neutralized with NaHCO ₃ water, and 100 parts of distilled water was added. After permeation, the sample is dried to obtain sulfated curdlan. Hereinafter, this is referred to as CA4.

Production Example 11 0.50 part of curdlan (manufactured by Wako Pure Chemical Industries, Ltd.) is added to 40.0 parts of dehydrated and dried dimethyl sulfoxide (DMSO), and the mixture is stirred at room temperature for 2 hours. After stirring, 0.5 part of piperidine sulfate is further added, and the mixture is allowed to react for 30 minutes while keeping at 95 ° C. Next, DMSO was removed by distillation under reduced pressure, acetone was added to the residue, a precipitate was collected, washed with water, neutralized with NaHCO ₃ water, and 100 parts of distilled water was added. After the dialysis treatment, the sample is dried to obtain a sulfated curdlan. Hereinafter, this is referred to as CA5.

Production Example 12 Curdlan (0.50 parts) was added to dehydrated and dried dimethylsulfoxide (DMSO) (40.0 parts), and the mixture was stirred at room temperature for 2 hours. After stirring, 2.0 parts of piperidine sulfuric acid is further added, and the mixture is reacted for 120 minutes while maintaining the temperature at 95 ° C. Next, DMSO was removed by vacuum distillation, acetone was added to the residue to collect a precipitate, which was washed with water and then washed with NaHCO _3.
Neutralize with water and add 100 parts of distilled water. After the dialysis treatment, the sample is dried to obtain a sulfated curdlan. Hereinafter, this is referred to as CA6.

Production Example 13 0.50 part of curdlan was added to 40.0 parts of dehydrated and dried dimethyl sulfoxide (DMSO, and stirred for 2 hours at room temperature. After stirring, 0.5 part of piperidine sulfuric acid was further added and 65 parts of The reaction was carried out for 30 minutes while keeping at 0 ° C. Next, DMSO was removed by vacuum distillation, acetone was added to the residue, a precipitate was collected, washed with water, and washed with NaHCO _3.
Neutralize with water and add 100 parts of distilled water. After the dialysis treatment, the sample is dried to obtain a sulfated curdlan. Hereinafter, this is referred to as CA7.

Production Example 14 Pyridine 40.0 obtained by dehydrating and drying 0.50 parts of curdlan
And stirring at room temperature for 2 hours. After stirring, 2.0 parts of piperidine sulfate is further added, and the mixture is reacted for 120 minutes while maintaining at 65 ° C. Next, pyridine was removed by distillation under reduced pressure, acetone was added to the residue, and a precipitate was collected. The precipitate was washed with water, neutralized with NaHCO ₃ water, and concentrated.
Add 00 parts of distilled water. After the dialysis treatment, the sample is dried to obtain a sulfated curdlan. Hereinafter, this is referred to as CA8.

Production Example 15 Pyridine 40.0 obtained by dehydrating and drying 0.50 parts of curdlan
And stirring at room temperature for 2 hours. After stirring, 2.0 parts of hydrochloric acid is further added, and the mixture is reacted for 60 minutes while maintaining at 80 ° C. Next, pyridine is removed by distillation under reduced pressure, acetone is added to the residue, and a precipitate is collected. The precipitate is washed with water, and after dialysis, the sample is dried. Further, the obtained solid was added to 40.0 parts of dehydrated and dried pyridine,
Stir at room temperature for hours. After stirring, 0.1 part of piperidine sulfate is further added, and the mixture is reacted for 60 minutes while maintaining at 80 ° C. Next, pyridine was removed by distillation under reduced pressure, acetone was added to the residue, and a precipitate was collected.
Neutralize with NaHCO ₃ water and add 100 parts of distilled water. After the dialysis treatment, the sample is dried to obtain a sulfated curdlan. Hereinafter, this is referred to as CA9.

Production Example 16 Pyridine 40.0 obtained by dehydrating and drying 0.50 parts of curdlan
And stirring at room temperature for 2 hours. After stirring, 2.0 parts of hydrochloric acid is further added, and the mixture is reacted for 60 minutes while maintaining at 80 ° C. Next, pyridine is removed by distillation under reduced pressure, acetone is added to the residue, and a precipitate is collected. The precipitate is washed with water, and after dialysis, the sample is dried. Further, the obtained solid was added to 40.0 parts of dehydrated and dried pyridine,
Stir at room temperature for hours. After stirring, 0.2 part of piperidine sulfate is further added, and the mixture is reacted for 60 minutes while maintaining the temperature at 80 ° C. Next, pyridine was removed by distillation under reduced pressure, acetone was added to the residue, and a precipitate was collected.
Neutralize with NaHCO ₃ water and add 100 parts of distilled water. After the dialysis treatment, the sample is dried to obtain a sulfated curdlan. Hereinafter, this is referred to as CA10.

Production Example 17 Pyridine 40.0 obtained by dehydrating and drying 0.50 parts of curdlan
And stirring at room temperature for 2 hours. After stirring, 0.5 part of hydrochloric acid is further added, and the mixture is reacted for 30 minutes while maintaining the temperature at 80 ° C. Next, pyridine is removed by distillation under reduced pressure, acetone is added to the residue, and a precipitate is collected. The precipitate is washed with water, and after dialysis, the sample is dried. Further, the obtained solid was added to 40.0 parts of dehydrated and dried pyridine,
Stir at room temperature for hours. After stirring, 0.1 part of piperidine sulfate is further added, and the mixture is reacted for 60 minutes while maintaining at 80 ° C. Next, pyridine was removed by distillation under reduced pressure, acetone was added to the residue, and a precipitate was collected.
Neutralize with NaHCO ₃ water and add 100 parts of distilled water. After the dialysis treatment, the sample is dried to obtain a sulfated curdlan. Hereinafter, this is referred to as CA11.

Production Example 18 Pyridine 40.0 obtained by dehydrating and drying 0.50 parts of curdlan
And stirring at room temperature for 2 hours. After stirring, 0.5 part of hydrochloric acid is further added, and the mixture is reacted for 30 minutes while maintaining the temperature at 80 ° C. Next, pyridine is removed by distillation under reduced pressure, acetone is added to the residue, and a precipitate is collected. The precipitate is washed with water, and after dialysis, the sample is dried. Further, the obtained solid is added to 40.0 parts of dehydrated and dried pyridine, and the mixture is stirred at room temperature for 2 hours. After stirring, 0.2 part of piperidine sulfate is further added, and the mixture is reacted for 60 minutes while maintaining the temperature at 80 ° C. Next, pyridine was removed by distillation under reduced pressure, acetone was added to the residue, and a precipitate was collected.
Neutralize with NaHCO ₃ water and add 100 parts of distilled water. After the dialysis treatment, the sample is dried to obtain a sulfated curdlan. Hereinafter, this is referred to as CA12.

The average molecular weight and sulfur content of the sulfated polysaccharide obtained in each of the above Production Examples and the water solubility of the sample adjusted to 20 ° C. are shown in Table 1.

[0032]

[Table 1]

Hereinafter, specific examples of the case where the cement additive of the present invention is used for concrete will be described, but the present invention is not limited to these embodiments.

【Example】

(Materials used) 1) Fine aggregate: Oigawa water-based land sand (specific gravity = 2.63, coarse grain ratio = 2.75) 2) Coarse aggregate: Hard crushed stone from Ome (specific gravity = 2.64, maximum) 3) Cement: ordinary Portland cement (specific gravity = 3.)
16, Onoda Cement Co., Ltd.) 4) High-performance water reducing agent: Melamine sulfonate formalin condensate (manufactured by NMB, Leobuild NL-4000, hereinafter referred to as MS) Naphthalene sulfonate formalin condensate (NMB, Leobuild) SP-9N, hereinafter referred to as BNS) 5) Admixture for non-separable concrete in water: Akris 12SS (manufactured by NMB, hereinafter AK-1)
Recorded as 2SS. ) And Acris SP (NMB,
Hereinafter, it is described as AK-SP. 6) Admixture for poorly-mixed concrete: Bozoris No. 70L (NMB, below 70
Indicated as L. 7) Thickener: cellulose ether (90SH-3 manufactured by Shin-Etsu Chemical Co., Ltd.)
0000, hereinafter referred to as MC. )

1. High fluidity, low separability concrete The target slump flow 55 according to the formulation shown in Table 2
A concrete composition designed to be 0-600 mm and a target air volume of 4.5% by volume is prepared, each material is weighed so that the mixing amount becomes 80 liters, and all the materials are put into a 100 liter pan-type forced mixer. After that, the mixture was kneaded for 90 seconds to prepare a concrete having high fluidity and low separability. The obtained concrete was sampled immediately after kneading and after 60 minutes, and its slump flow, air volume,
The setting time and the flow time were measured, and the separation resistance was evaluated by visual observation. Furthermore, the compressive strength of the concrete at the age of 28 days was also measured. These results are shown in Table 3.

[0036]

[Table 2]

Table 3 shows Examples 1 to 12 (sample: CLS,
XGS, MC1-4, CS1-8) and Examples 13-18
(Sample: Combination of CA9-12 and high-performance water reducing agent) and commercially available high-performance water reducing agent for comparing water reduction rate, air entrainment, decrease in fluidity with time, setting time, separation resistance and compressive strength The test results of evaluation of a concrete to which a melamine sulfonate formalin condensate as a dispersant was added (Comparative Example 1) and a concrete to which a melamine sulfonate formalin condensate and cellulose ether were added (Comparative Example 2) were shown. .

(Measurement method) 1) Slump flow: According to the Japan Society of Civil Engineers, guideline for design and construction of inseparable concrete in water (draft). 2) Flow time: Separation resistance was evaluated by measuring the time until the flow spread stopped. In addition, when it is within the target slump flow value range (550-600 mm),
When the flow velocity is 55 or more, separation resistance is exhibited.

3) Visual observation-1: Separation resistance was determined by visually observing the separation state of the materials, and the materials were classified into the following categories. A: Cement, water, fine aggregate and coarse aggregate flowed together and good separation resistance was observed. B: Good separation resistance was observed, but viscosity was excessive. C: Separation of the used materials was observed. 4) Air volume: According to JIS A1128. 5) Compression strength: According to JIS A1118. 6) Setting time: See Annex 1 of JIS A 6204.

As can be seen from the results shown in Table 3, when the cement additive of the present invention was used in high-flow / low-separation concrete (Examples 1 to 18), the following effects were confirmed. You. 1) Water reduction: As is clear from comparison with Comparative Example 1,
Shows water-reduction equivalent to high-performance water-reducing agent. 2) Air entrainment: Although air entrainment is extremely low, Comparative Example 2 has a large air entrainment, so the amount of air was adjusted by adding an antifoaming agent.

3) Decrease in fluidity over time: Slump flow hardly decreases after 60 minutes, and the decrease in fluidity over time is extremely small. 4) Setting time: As is clear from comparison with Comparative Example 1,
Shows the same setting time as high performance water reducing agent and does not delay setting. On the other hand, Comparative Example 2 shows a setting retardation of about 3 hours.

5) Separation resistance: As is clear from comparison with Comparative Example 2, more excellent material separation resistance was obtained with a smaller amount of use, and higher fluidity was obtained. 6) Compressive strength (age 28 days): As is clear from comparison with Comparative Example 1, the compressive strength is 14 to 17% higher than that of the high-performance water reducing agent. Also, a compression strength about 10% higher than that of Comparative Example 2 is obtained. Furthermore, the cement additive of the present invention was very easily dissolved in water and was extremely excellent in handling.

[0043]

[Table 3]

2. Underwater non-separable concrete Target slump flow 45
A concrete composition designed to be 0 to 550 mm and a target air volume of 4.0% by volume is prepared, each material is weighed so that the mixing amount is 80 liters, and all the materials are put into a 100 liter pan-type forced mixer. After that, the mixture was kneaded for 90 seconds to prepare a non-separable concrete in water. The obtained concrete was sampled immediately after kneading and after elapse of 60 minutes, and its slump flow, air amount, and flow time were measured. The separation resistance of the concrete in water was evaluated by visual observation. These results are shown in Table 5.

[0045]

[Table 4]

Table 5 shows Examples 19 to 21 (sample: MC
2, CA2, 3) and concrete containing a commercially available admixture for underwater separable concrete in order to compare the water reduction rate, air entrainment, decrease in fluidity with time, and inseparability in water (Comparative Example 3), The results of tests performed using concrete (Comparative Example 4) to which a melamine sulfonate formalin condensate, which is a high-performance water reducing agent, was added are shown.

(Measurement method) 1) Slump flow: According to the Japan Society of Civil Engineers, guideline for design and construction of underwater inseparable concrete (draft). 2) Flow time: Separation resistance was evaluated by measuring the time until the flow spread stopped. In addition, when it is within the target slump flow value range (450 to 550 mm),
When the flow velocity is 50 or more, separation resistance is exhibited.

3) Visual observation-1: Evaluated by the same method as for the high-flow, low-separation concrete. 4) Visual observation-2: 1,500 ml of water is put into a 2,000 ml measuring cylinder, and 250 g of mixed concrete is dropped freely into the measuring cylinder. One minute after the free fall, the suspension state of water in the measuring cylinder was visually observed and evaluated. A: Cement, water, fine aggregate and coarse aggregate flowed together, showed good separation resistance, and no water suspension was observed. B: Separation resistance of the material was observed, but some water suspension was observed. C: Separation of materials was observed, and remarkable suspension of water was observed. 5) Air volume: According to JIS A1128.

[0049]

[Table 5]

As can be seen from the results shown in Table 5, when the cement additive of the present invention is used in water-inseparable concrete (Examples 19 to 21), the following effects are confirmed. 1) Water-reduction: As is apparent from comparison with Comparative Example 3, the same water-reduction was shown in an amount smaller than the addition amount of the admixture for in-water inseparable concrete. 2) Air entrainment: Air entrainment equivalent to Comparative Examples 3 and 4 was exhibited, and no excess air entrainment was observed.

3) Separation resistance: The flow time was longer than that using the high-performance water reducing agent of Comparative Example 4, and was equivalent to that of Comparative Example 3. In addition, as apparent from the visual observation-1, the same separation resistance as that of Comparative Example 3 was shown. 4) Separation resistance in water: According to visual observation-2, the concrete of Comparative Example 4 was remarkably separated in water, resulting in suspension of water. However, as in Comparative Example 3, no separation in water was observed. No water suspension occurred.

3. High-strength concrete Target slump 23.0 ± with the composition shown in Table 6
After preparing a concrete composition designed to be 2 cm and a target air volume of 4.0% by volume, each material was weighed so that the mixing amount was 80 liters, and all the materials were put into a 100 liter pan-type forced mixer. For 90 seconds to prepare a high-strength concrete. The obtained concrete was sampled immediately after kneading and after 60 minutes had passed, and its slump flow, air volume, and setting time were measured.
The compressive strength of the concrete at the age of 28 days was also measured. These results are shown in Table 7.

[0053]

[Table 6]

Table 7 shows Examples 22 to 24 (sample: MC
2, CA2, 3) and a commercial high-performance water-reducing agent, melamine sulfonate formalin condensate, was added to compare the water reduction rate, air entrainment, decrease in fluidity with time, setting time, and compressive strength. Concrete (Comparative Example 5),
The results of a test performed using a concrete to which a naphthalene sulfonate formalin condensate was added (Comparative Example 6) were shown.

(Measurement method) 1) Slamp: According to JIS A1101. 2) Slump flow: According to the Japan Society of Civil Engineers, guidelines for designing and constructing underwater non-separable concrete (draft). 3) Air volume: According to JIS A1128. 4) Compression strength: according to JIS A1118. 5) Setting time: See Annex 1 of JIS A 6204.

[0056]

[Table 7]

As can be seen from the results shown in Table 7, when the cement additive of the present invention is used for high-strength concrete (Examples 22 to 24), the following effects are confirmed. 1) Water reduction: As is apparent from comparison with Comparative Examples 5 and 6, the same amount of slump and slump flow was exhibited with a smaller amount of use, and excellent water reduction was exhibited. 2) Air entrainment: Air entrainment almost equivalent to Comparative Examples 5 and 6 was shown.

3) Setting time: The same setting time as in Comparative Example 5 was observed, and the onset and termination tended to be earlier than in Comparative Example 6. 4) Compressive strength: Compressive strength equivalent to that of the concrete using the high-performance water reducing agent of Comparative Examples 5 and 6 was exhibited.

4. Secondary product concrete Target slump 8 ± 1c with the composition shown in Table 8
m, a concrete composition designed to a target air volume of 2.0% by volume was prepared, each material was weighed so that the mixing amount was 80 liters, and all the materials were put into a 100 liter pan-type forced mixer. For 90 seconds to prepare a secondary product concrete. The obtained concrete was sampled immediately after kneading and after a lapse of 60 minutes, and its slump, air volume, and compressive strength of the concrete at a material age of 28 days were measured. Furthermore, the compressive strength of the concrete after steam curing was also measured. In addition, the appearance of the concrete surface was visually evaluated. These results are shown in Table 9.

[0060]

[Table 8]

Table 9 shows Examples 25 to 27 (sample: MC
3, CA2, 3) and concrete to which melamine sulfonate formalin condensate, which is a commercially available high-performance water reducing agent, was added in order to compare the water reduction rate, air entrainment, decrease in fluidity with time, and compressive strength (comparison) Example 7) shows the results of a test performed using a concrete to which a naphthalene sulfonate formalin condensate was added (Comparative Example 8).

(Measurement method) 1) Slamp: According to JIS A1101. 2) Air volume: According to JIS A1128. 3) Compression strength: According to JIS A1118. 4) Steam curing conditions: After pre-curing for 2 hours at 20 ° C., the temperature is raised to 65 ° C. at a rate of about 18.0 ° C./hr. After performing steam curing at 65 ° C. for 3 hours continuously, it is cooled to 20 ° C. at a cooling rate of about 4.30 ° C./hr. 5) Visual observation-3: In order to observe the skin surface of concrete, a specimen having a member size of 10 × 10 × 50 cm was prepared.
The concrete surface after curing was visually observed and evaluated. A: A state in which there is no void due to unevenness, junkers or bubbles on the skin surface of the concrete, and the appearance is extremely excellent. B: Unevenness due to irregularities, junkers, air bubbles, and the like is conspicuous to some extent on the concrete surface, and the appearance is poor.

As can be seen from the results shown in Table 9, when the cement additive of the present invention is used in secondary concrete (Examples 25 to 27), the following effects are confirmed. 1) Water-reduction: As is apparent from comparison with Comparative Examples 7 and 8, the same water-reduction was shown with a small amount of addition. 2) Air entrainment: Air entrainment equivalent to Comparative Examples 7 and 8 was shown.

3) Compressive strength: The compressive strength under the curing conditions of both standard and steam was equivalent to that of Comparative Examples 7 and 8, as is clear. 4) Concrete skin surface: As apparent from visual observation-3, the skin surface condition was equivalent to that of Comparative Example 7, and the skin surface appearance was better than that of Comparative Example 8.

[0065]

[Table 9]

5. Poor mix concrete Target slump 18 ± 1 by mix shown in Table 10
cm, and a concrete composition designed to have a target air volume of 4.5% by volume was prepared, each material was weighed so that the mixing amount was 80 liters, and all the materials were put into a 100 liter pan-type forced mixer. For 90 seconds to prepare a poorly-mixed concrete. The obtained concrete was sampled immediately after kneading and after a lapse of 60 minutes, and its slump, air amount, compressive strength and bleeding amount of the concrete at the age of 28 days were measured. Further, the workability of the fresh concrete was visually evaluated. These results are shown in Table 11.

[0067]

[Table 10]

Table 11 shows Examples 28 to 29 (sample: M
C3, CA2, 3) and concrete to which a commercially available admixture for poorly-mixed concrete was added in order to compare the water reduction rate, air entrainment, decrease in fluidity with time, setting time, and compressive strength (Comparative Example 9) The results of tests performed using concrete containing a melamine sulfonate formalin condensate as a performance water reducing agent (Comparative Example 10) and concrete containing a naphthalene sulfonate formalin condensate (Comparative Example 11) are shown.

(Measurement method) 1) Slam: According to JIS A1101. 2) Air volume: According to JIS A1128. 3) Compression strength: According to JIS A1118. 4) Setting time: JIS A 6204 Appendix 1
by. 5) Bleeding: According to JIS A 1123. 6) Visual observation-4: In order to evaluate the workability of concrete, the slump deformation state was visually observed,
Furthermore, the slump deformation due to tamping was observed and evaluated. A: The balance between the fluidity and the viscosity of concrete was excellent, and a slump without collapse was shown. Further, a slump state without deformation of the slump due to tamping was shown. B: The balance between the fluidity and the viscosity of the concrete was poor, and there was a tendency that some or all of the concrete collapsed during slumping. In addition, the slump deformation due to tamping also collapsed as a whole.

[0070]

[Table 11]

As can be seen from the results shown in Table 11,
When the cement additive of the present invention is used in poorly-mixed concrete (Examples 28 to 30), the following effects are confirmed. 1) Water-reducing property: The same water-reducing property was shown by using about 10% less than the poorly-mixed concrete admixture of Comparative Example 9. In addition, the same water-reducing property was shown with the use amount of about 10% less than Comparative Examples 10 and 11. 2) Air entrainment: Air entrainment equivalent to Comparative Examples 9, 10 and 11 was shown.

3) Bleeding: Comparative Examples 10 and 1
As is clear from comparison with Example 1, the bleeding amount of the concrete in Examples 24 to 26 showed a small value, and further, as compared with Comparative Example 9, showed a slightly smaller value, so that the bleeding suppressing effect was recognized. . 4) Compressive strength: Compressive strength characteristics equivalent to those of Comparative Examples 9 to 11 were exhibited. 5) Workability: As is clear from visual observation-4, the workability was as good as the concrete using the poorly-mixed concrete admixture of Comparative Example 9, and the workability was clearly superior to Comparative Examples 10 and 11. .

[0073]

EFFECTS OF THE INVENTION The use of the cement additive of the present invention is extremely excellent because both the effects obtained by the high-performance water reducing agent and the effects obtained by the thickener can be obtained at once. . High flow and low separability concrete,
It is very advantageously used for the production of cement compositions such as high-strength concrete, water-inseparable concrete, secondary product concrete, poorly placed concrete, and the like.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-21949 (JP, A) JP-A-61-72664 (JP, A) JP-A-62-30649 (JP, A) 85790 (JP, A) JP-A-5-85791 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 24/38 C04B 24/10 CA (STN) REGISTRY (STN)

Claims (4)

(57) [Claims] 1. A cement water reducing agent containing a sulfated polysaccharide having an average molecular weight of 5,000 to 200,000 obtained by sulfating a polysaccharide. 2. The cement water reducing agent according to claim 1, wherein the sulfur content of the sulfated polysaccharide is from 0.01 to 20.0% by elemental analysis. 3. The cement water reducing agent according to claim 2, wherein the sulfur content of the sulfated polysaccharide is from 1.0 to 20.0% by elemental analysis. 4. The method according to claim 1, wherein the polysaccharide is cellulose, cellulosue
The cement water reducing agent according to any one of claims 1 to 3, which is selected from ter, curdlan, and xanthan gum.