JP2000281412A - Cement admixture and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement admixture which can improve the flowability of mortar and concrete, can quickly develop their strengths, and has an excellent early strength development at low temperature for the mortar and the concrete, and to provide a cement composition. SOLUTION: This cement admixture comprises a strength-enhancing material comprising anhydrous gypsum and/or silica particles, at least one compound selected from formic acid, lactic acid, acetic acid and their salts, and at least one compound selected from sulfites, bisulfites, pyrosulfates, pyrosulfites and pyrobisulfites. The cement admixture preferably further contains a high performance water-reducing agent. The cement composition comprises the cement admixture and a cement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a cement admixture and a cement composition mainly used in the fields of civil engineering and construction.

[0002]

2. Description of the Related Art In recent years, the performance required of cement and concrete has been increasing more and more, and among them, research on increasing the strength and early strengthening of cement and concrete has been actively conducted. The strength of cement / concrete greatly depends on the water / cement ratio. To reduce the water / cement ratio as much as possible, water reducing agents and high-performance water reducing agents specified in JIS A 6204 “Chemical admixture for concrete” are used. It is used. However, when the water / cement ratio is reduced, there is a problem that workability deteriorates. On the other hand, there have been developed many methods for realizing high strength and early strengthening by promoting hydration of cement. For example, various methods have been proposed for increasing the strength of cement / concrete by using an accelerator such as calcium nitrate, calcium nitrite, calcium chloride, formic acid, sodium nitrate and calcium formate, or lactic acid and its salt. US Patent No. 3427175
No., JP-A-50-80315, JP-A-50-10998, JP-A-55-71653, U.S. Pat.No. 3,801,338, or British Patent No. 1,252,501, British Patent No. 1,252,502) .
Concrete mixed with these accelerators has a problem that slump loss is large and it is difficult to secure working time. The present inventors previously proposed a cement admixture capable of suppressing slump loss of concrete and achieving high strength (Japanese Patent Application Laid-Open No. 10-265249).

[0003]

However, this cement admixture has a problem that the early strength is not sufficient, and especially the initial strength at low temperatures is not sufficient.
Thus, the present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, obtained the knowledge that the above-mentioned problems can be solved by using a specific cement admixture, and completed the present invention. Was.

[0004]

That is, the present invention provides (1)
Strength enhancing material comprising anhydrous gypsum and / or silica fine powder, at least one or more selected from formic acid, lactic acid, acetic acid and salts thereof, and sulfite, bisulfite, pyrosulfate, pyrosulfite and A cement admixture containing at least one selected from pyrobisulfite; (2) the above-mentioned (1) further containing a high-performance water reducing agent
(3) A cement composition comprising the cement admixture according to any one of (1) and (2) and cement.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The anhydrous gypsum of the present invention is not particularly limited. For example, it is obtained by heat-treating natural anhydrous gypsum, hemihydrate gypsum and dihydrate gypsum which are produced naturally, and is produced as an industrial by-product. Use of things is possible. The particle size of anhydrous gypsum is 2500 cm ² / g in terms of Blaine specific surface area
The above are preferred. If it is less than 2500 cm ² / g, sufficient strength development may not be obtained.

[0007] The silica fine powder of the present invention is a fine powder of a substance having siliceous as a main component and having latent hydraulic property, and is not particularly limited.
Fine powder such as silica dust, diatomaceous earth, silicate clay, fly ash and blast furnace slag. In the present invention, at least one of these can be used.
The particle size of the silica fine powder is 4000 in terms of Blaine specific surface area.
cm ² / g, more preferably at least 6000 cm ² / g, more preferably more than 8000 cm ² / g. 4000cm ² / g
If it is less than 30, sufficient strength development may not be obtained.

The formic acid, lactic acid and acetic acid (hereinafter referred to as formic acids) of the present invention generally belong to an organic compound called oxycarboxylic acid. For example, oxycarboxylic acid includes succinic acid, malic acid, tartaric acid, gluconic acid and the like. The effects of the present invention cannot be achieved with such salts and the like. Other oxycarboxylic acids exhibiting a strong retarding property have different effects. The formic acids of the present invention are, for example, formic acid, lactic acid, acetic acid and salts thereof, and as such salts, sodium salt, potassium salt, lithium salt, calcium salt, magnesium salt, barium salt, aluminum Salts, zinc salts and ammonium salts. In the present invention,
At least one of these can be used.

The sulfite, bisulfite, pyrosulfite, pyrosulfite and pyrobisulfite (hereinafter referred to as "sulfites") of the present invention are not particularly limited. Potassium, lithium sulfite, calcium sulfite, sodium bisulfite, potassium bisulfite, lithium bisulfite, calcium bisulfite, sodium pyrosulfate, potassium pyrosulfate, lithium pyrosulfate, calcium pyrosulfite, sodium pyrosulfite, potassium pyrosulfite, pyrosulfite Lithium, calcium pyrosulfite, sodium pyrobisulfite, potassium pyrobisulfite, lithium pyrobisulfite and calcium pyrobisulfite. In the present invention, at least one or more of these can be used.

The high-performance water reducing agent of the present invention is not particularly limited, but is generally referred to as a naphthalene type, a melamine type, a polycarboxylic acid type, an aminosulfonic acid type or the like. Are of a liquid type and a powder type. For example, Kao's product names "Mighty 2000WH", "Mighty 100", "Mighty 150", and Denka FT-500, Denka FT-8
0 ", a product name" Cell Flow 110P "manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
Showa Denko's product name "Melment F-10", "Molmaster 10", "Molmaster 20" and Nippon Sika's product name "Seakament 1000H" are available. As polycarboxylic acid type, Grace Chemicals Product name "Darlex Super 200" manufactured by NMB, product name "Leobuild SP-8HS" manufactured by NMB, product name manufactured by Takemoto Yushi Corporation "Tupole HP-11", "Tupole HP-11", "Paul" Fine 510N ", trade name" Palic FP-1 "manufactured by Fujisawa Pharmaceutical Company Limited
00U "," PARIC FP-200 "and trade names" Sunflow PS "and" Sunflow HS700 "manufactured by Nippon Paper Industries. Many other high-performance water reducing agents are commercially available.

The mixing ratio of each component of the cement admixture of the present invention is not particularly limited, but the cement admixture may be anhydrous gypsum and / or silica fine powder (hereinafter referred to as a strength enhancer), formic acids and If it contains sulfites,
The mixing ratio of the strength enhancer in 100 parts by weight of the cement admixture is preferably 40 to 80 parts by weight, and more preferably 50 to 70 parts by weight. If the amount is less than 40 parts by weight, sufficient strength development may not be obtained, and if it exceeds 80 parts by weight, sufficient slump retention may not be obtained. The mixing ratio of formic acids is preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight. If the amount is less than 5 parts by weight, sufficient early strength may not be obtained, and if it exceeds 40 parts by weight, sufficient slump retention may not be obtained. The compounding ratio of the sulfites is preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight. If the amount is less than 5 parts by weight, sufficient slump retention may not be obtained, and if it exceeds 40 parts by weight, sufficient early strength may not be obtained.

When the cement admixture contains a strength enhancer, formic acids, sulfites and a high-performance water reducing agent, the mixing ratio of the strength enhancer is 3 parts per 100 parts by weight of the cement admixture.
The amount is preferably 0 to 60 parts by weight, more preferably 40 to 50 parts by weight. If the amount is less than 30 parts by weight, sufficient strength development may not be obtained, and if it exceeds 60 parts by weight, sufficient slump retention may not be obtained. The mixing ratio of formic acids is preferably 5 to 30 parts by weight, more preferably 10 to 25 parts by weight. If the amount is less than 5 parts by weight, sufficient early strength may not be obtained, and if it exceeds 30 parts by weight, sufficient slump retention may not be obtained. The compounding ratio of the sulfites is preferably 5 to 30 parts by weight, more preferably 10 to 25 parts by weight. If the amount is less than 5 parts by weight, sufficient slump retention may not be obtained, and if it exceeds 30 parts by weight, sufficient early strength may not be obtained. The mixing ratio of the high-performance water reducing agent is preferably 1 to 15 parts by weight in terms of solid content, and 3 to 1 part by weight.
0 parts by weight is more preferred. If the amount is less than 1 part by weight, sufficient fluidity may not be obtained. If the amount exceeds 15 parts by weight, material separation may occur or sufficient early strength may not be obtained.

The amount of the cement admixture of the present invention relative to the cement is not particularly limited. However, when the cement admixture contains a strength enhancer, formic acids and sulfites, it contains the cement and the cement admixture. 1 to 15 parts by weight is preferable in 100 parts by weight of the resulting cement composition.
-10 parts by weight is more preferred. If the amount is less than 1 part by weight, sufficient effects may not be obtained on the retention of slump, high strength, early strengthening, and initial strength development at low temperature, and even if it exceeds 15 parts by weight, further enhancement of the effect is expected. Can not.

[0014] The cement admixture is a strength enhancer, formic acids,
When it contains a sulfite and a high-performance water reducing agent, it is preferably 1 to 10 parts by weight, more preferably 3 to 7 parts by weight, in 100 parts by weight of a cement composition containing cement and a cement admixture. If the amount is less than 1 part by weight, sufficient effects may not be obtained on the retention of slump, high strength, early strengthening and initial strength development at low temperature, and even if the amount exceeds 10 parts by weight, further enhancement of the effect is expected. Can not.

[0015] The cement admixture of the present invention is usually used in the form of powder, but formic acids, sulfites and a high-performance water reducing agent are used.
Because it is soluble or liquid in water and has a low hydration activity of the strength enhancer, it does not immediately show hydraulicity even when mixed with water, so the slurry of the cement admixture of the present invention mixed with water is used. It is possible to use.

In the present invention, in addition to the strength enhancer, formic acids, sulfites and high-performance water reducing agent, it is possible to use a coagulation accelerator if necessary. As the setting accelerator, for example, aluminates such as sodium aluminate, potassium aluminate and lithium aluminate, carbonates such as sodium carbonate, potassium carbonate, lithium carbonate, sodium bicarbonate, potassium bicarbonate and lithium bicarbonate, Nitrate and nitrite such as bicarbonate, sodium nitrate, potassium nitrate, lithium nitrate, calcium nitrate, sodium nitrite, potassium nitrite, lithium nitrite and calcium nitrite, sodium sulfate, potassium sulfate, lithium sulfate, gypsum dihydrate, half There are inorganic sulfates other than anhydrous gypsum such as water gypsum and aluminum sulfate, calcium hydroxide, calcium oxide, alum, thiocyanate, thiosulfate, and amino alcohols such as triethanolamine. By using at least one of these in combination, it is possible to further promote high strength and early reinforcement.

As the cement of the present invention, ordinary, early strength,
There are various portland cements such as ultra-high strength, low heat and moderate heat, various cements obtained by mixing these cements with blast furnace slag, fly ash and silica, filler cements obtained by mixing limestone powder and the like, and alumina cements.

The cement admixture and the cement composition of the present invention may contain, in addition to aggregates such as sand and gravel, reinforcing fiber materials, cement expanders, AE agents, thickeners, rust preventives, antifreezes, and polymers. Emulsions, clay minerals such as bentonite and montmorillonite, zeolite, ion exchangers such as hydrotalcite and hydrocalmite, inorganic phosphates, and boric acid are used in combination within a range that does not substantially inhibit the effects of the present invention. Is possible.

In the production of the cement admixture and the cement composition of the present invention, any existing stirring device can be used as a mixing device, for example, a tilting mixer, an omni mixer, a V-type mixer, a Henschel mixer. There are a mixer and a Nauta mixer. As a mixing method, each material may be mixed separately at the time of construction, or a part or all of them may be mixed in advance.

[0020]

The present invention will be described below in detail with reference to examples.

Example 1 Table 1 shows various strength enhancers, formic acids A and sulfites (1).
And a cement admixture was prepared. 5 parts by weight of this cement admixture was mixed with 100 parts by weight of a cement composition containing cement α and the cement admixture, and a cement composition / sand ratio = 1/3 and a water / cement composition ratio = 50. % Mortar was prepared. 2 of this mortar
The change with time of the flow and the measurement of the compressive strength at 0 ° C. were measured. Table 1 shows the results. <Materials Used> strength enhancing material I: Blaine specific surface area value 4120cm ² / g natural anhydrite strength enhancing material Hollow: Blaine specific surface area 9130cm ² / g of commercially available silica fume strength enhancing material Ha: Blaine specific surface area value 8960cm ² / g Commercial fly ash of Japan Strength enhancer d: Commercial blast furnace slag with a specific surface area of 7710 cm ² / g Strength enhancer E: Equiweight mixture of strength enhancer A and strength enhancer B Formic acids A: Reagent primary calcium formate Sulfites (1): Reagent 1st grade potassium sulfite Cement α: Early strength Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Sand: JIS standard sand (conforming to ISO 679) Water: tap water <Test method> Compressive strength: Measured according to JIS A 1108. Flow test: Measured according to JIS R 5201.

[0022]

[Table 1]

The cement composition containing the cement admixture of the present invention shows good mortar flow retention and compressive strength. On the other hand, the comparative example in which the cement admixture of the present invention was not blended (Experiment No. 1-14) shows that the mortar had a large flow loss.

Example 2 A cement admixture was prepared by mixing 60 parts by weight of a strength enhancer (e), 20 parts by weight of various formic acids shown in Table 2, and 20 parts by weight of sulfite (1). Was performed in the same manner as in Example 1 except that 5 parts by weight of a cement admixture was added to 100 parts by weight of a cement composition containing For comparison, citric acid was blended, and the same test was performed. Table 2 shows the results. <Materials> Formic acids A: Reagent primary calcium formate Formic acids B: Reagent primary formic acid Formic acids C: Reagent primary sodium formate Formic acids D: Reagent primary potassium formate Formic acids E: Reagent primary lactic acid Formic acids F : Reagent primary calcium lactate Formic acid G: Reagent primary sodium lactate Formic acid H: Reagent primary potassium lactate Formic acid I: Reagent primary calcium acetate Formic acid J: Equiweight mixture of formic acid A and formic acid F Formic acid K: formic acid A, formic acid F and formic acid I equal weight mixture Citric acid: reagent primary citric acid

[0025]

[Table 2]

The cement composition containing the cement admixture of the present invention shows good fluidity and compressive strength. On the other hand, a comparative example containing citric acid (Experiment No.2-11)
Indicates that the mortar has no flow loss, but does not cure at all.

Example 3 60 parts by weight of a strength enhancer e, 20 parts by weight of formic acids A and Table 3
A cement admixture was prepared by blending 20 parts by weight of various sulfites shown in the following, and 100 parts by weight of the cement composition containing cement α and the cement admixture, except that 5 parts by weight of the cement admixture was blended. , All in the same manner as in Example 1. Table 3 shows the results. <Materials> Sulfites (1): Reagent primary potassium sulfite Sulfites (2): Reagent primary sodium sulfite Sulfites (3): Reagent primary calcium sulfite Sulfites (4): Reagent primary ammonium sulfite (5): Reagent primary sodium bisulfite sulfite (6): Reagent primary potassium bisulfite sulfite (7): Reagent primary sodium pyrosulfite sulfite (8): Reagent primary potassium pyrosulfite sulfite (9) ): Reagent primary potassium potassium bisulfite sulfites (10): equal weight mixture of sulfites (1) and sulfites (8)

[0028]

[Table 3]

The cement composition to which the cement admixture of the present invention is blended has a small change with time in the mortar flow, shows good fluidity, and has excellent compressive strength.

Example 4 A cement admixture was prepared by blending 60 parts by weight of a strength enhancer (e), 20 parts by weight of formic acid A and 20 parts by weight of sulfite (1), and contained cement α and a cement admixture. All the procedures were performed in the same manner as in Example 1 except that the amount of the cement admixture was changed as shown in Table 4 in 100 parts by weight of the cement composition. Table 4 shows the results.

[0031]

[Table 4]

The cement composition containing the cement admixture of the present invention shows good mortar flow retention and compressive strength. On the other hand, the comparative example (Experiment No. 4-1) in which the cement admixture of the present invention was not blended showed that the mortar had large flow loss and low compressive strength.

Example 5 A cement admixture was prepared by mixing a strength-enhancing material (e), formic acid A, sulfite (1) and a high-performance water reducing agent (a) in the proportions shown in Table 5, and using cement α and the cement admixture. 5 parts by weight of the cement admixture was mixed with 100 parts by weight of the cement composition to prepare a mortar having a water / cement composition ratio of 40% and a cement composition / sand ratio of 1/3. Using this mortar, changes in flow over time and compressive strength were measured. Table 5 shows the results. <Materials used> High-performance water reducing agent a: Commercially available polyalkylallyl sulfonate

[0034]

[Table 5]

The cement composition containing the cement admixture of the present invention has good mortar flow retention and compressive strength. On the other hand, Comparative Examples in which the cement admixture of the present invention was not blended (Experiment Nos. 5-5 and 5-6) showed that the initial compressive strength development was low or the mortar flow loss was large.

Example 6 50 parts by weight of strength enhancer e, 20 parts by weight of formic acid A, 20 parts by weight of sulfite (1), and various high-performance water reducing agents 1 shown in Table 6
0 parts by weight to prepare a cement admixture, and a cement composition 10 containing cement α and the cement admixture.
Except that 5 parts by weight of the cement admixture was added to 0 parts by weight, the same procedure was performed as in Example 5. Table 6 shows the results. <Materials> High performance water reducing agent a: Commercially available polyalkylallyl sulfonate type high performance water reducing agent b: Commercially available aromatic amino sulfonate type High performance water reducing agent c: Commercially available melamine formalin resin sulfonate type High performance water reducing agent d: Commercially available polycarboxylic acid type high performance water reducing agent e: Commercially available polyalkyl allyl sulfonate type High performance water reducing agent f: Commercially available polyalkyl allyl sulfonate type

[0037]

[Table 6]

The cement composition containing the cement admixture of the present invention shows a good fluidity with little change in mortar flow with time and is excellent in compressive strength.

Example 7 A cement admixture was prepared by blending 50 parts by weight of a strength enhancer (e), 20 parts by weight of formic acid A, 20 parts by weight of sulfite (1) and 10 parts by weight of a high-performance water reducing agent a. In 100 parts by weight of a cement composition containing a cement admixture,
Except that the cement admixture was changed as shown in Table 7,
All operations were performed in the same manner as in Example 5. Table 7 shows the results.

[0040]

[Table 7]

The cement composition containing the cement admixture of the present invention exhibits good mortar flow retention and compressive strength. On the other hand, Comparative Example (Experiment No. 7-1) in which the cement admixture of the present invention was not blended showed that the mortar had a large flow loss and low compressive strength.

Example 8 Various cements shown in Table 8 and 50 parts by weight of a strength enhancer
5 parts by weight of a cement admixture was added to 100 parts by weight of a cement admixture containing 20 parts by weight of formic acid A, 20 parts by weight of sulfite (1) and 10 parts by weight of a high-performance water reducing agent a. . Using this cement composition, concrete having unit cement composition amount of 400 kg / m ³ , water / cement composition ratio = 40%, s / a = 46% was produced at an ambient temperature of 20 ° C., and slump and compressive strength were measured. Was done. In addition, concrete having the same composition was produced at an environmental temperature of 5 ° C., and the compressive strength at one day of age was measured. Table 8 shows the results. However, when a cement admixture is not blended, a high-performance water reducing agent a is blended,
The slump was the same as when the cement admixture was blended. <Materials used> Cement α: Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Cement β: Normal Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Cement B: Blast furnace cement B manufactured by Denki Kagaku Kogyo Co., Ltd. Sand: Himekawa, Niigata Prefecture Gravel: Himekawa, Niigata Prefecture Production, Gmax = 25mm

[0043]

[Table 8]

The cement composition containing the cement admixture of the present invention has good concrete slump retention and compressive strength. On the other hand, in the comparative examples (Experiment Nos. 8-4, 8-5, 8-6) in which the cement admixture of the present invention was not blended, the slump loss of the concrete was large and the compressive strength development was low. In particular, it shows that the compressive strength at a low temperature of 5 ° C. is extremely low.

[0045]

EFFECT OF THE INVENTION By using the cement admixture of the present invention, a cement composition which improves the fluidity of mortar and concrete, achieves high strength and early strengthening, and has excellent initial strength development at low temperatures. Is obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 18:14 22:14 22:08 24:04 24:30) 103: 32 103: 60 111: 20 ( 72) Inventor Morimasa Shiokawa 2209 Aomi, Aomi-cho, Nishikubiki-gun, Niigata Prefecture F term in the Aomi Plant of Denki Kagaku Kogyo Co., Ltd.

Claims (3)

[Claims] 1. A strength enhancing material comprising anhydrous gypsum and / or silica fine powder, at least one or more selected from formic acid, lactic acid, acetic acid and salts thereof, and sulfite, bisulfite, pyrosulfate A cement admixture comprising at least one selected from salts, pyrosulfites and pyrobisulfites. 2. The cement admixture according to claim 1, further comprising a high-performance water reducing agent. 3. A cement composition comprising the cement admixture according to claim 1 and cement.