JP2010235399A - Cement admixture and cement composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement admixture and a cement composition which promote the strength development of concrete. <P>SOLUTION: The cement admixture (1) contains a calcium sulfoaluminate having a Blaine specific surface area of ≥4,000 cm<SP>2</SP>/g and one or more than two kinds selected from a group of a formate, acetate and lactate. The cement admixture (2) further contains silica fine powder in addition to the cement admixture (1). The cement composition (3) contains the cement admixture (1) or (2) and the cement. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention mainly relates to a cement admixture and a cement composition that promote high strength of cement concrete used in the civil engineering and construction fields.
The cement concrete as used in the present invention is a general term for mortar and concrete.

  Conventionally, as a method for promoting the strengthening of cement concrete, in order to make the water / cement ratio as small as possible, as specified in JIS A 6204 “Chemical admixture for concrete”, water reducing agents and high performance water reducing agents are used. The use of agents is generally prevalent.

  On the other hand, regardless of the reduction in water / cement ratio, for example, using a setting accelerator such as calcium nitrate, calcium nitrite, calcium chloride and calcium nitrite, formic acid, sodium nitrate and calcium formate, lactic acid and its salts, etc. Various methods for increasing the strength of cement and concrete have been proposed (see Patent Documents 1, 2, 3, 4, 5, and 6). Furthermore, for example, a method for enhancing the strength of cement / concrete using a setting accelerator such as formic acid, lactic acid and salts thereof, calcium aluminate, anhydrous gypsum, and silica fine powder has been proposed (Patent Document 7). , 8).

U.S. Pat. No. 3,427,175 JP 50-80315 A JP-A-55-71653 U.S. Pat. No. 3,801,338 British Patent No. 1522501 British Patent No. 1522502 JP 2005-35856 A JP-A-8-301642

  The present invention provides a cement admixture and a cement composition that enhance the strength development of concrete.

The present invention comprises (1) a cement containing calcium sulfoaluminate having a specific surface area of 4000 cm ² / g or more and one or more selected from the group consisting of formate, acetate and lactate. An admixture, (2) a cement admixture of (1) further containing fine silica powder, and (3) a cement composition containing the cement admixture of (1) or (2) and cement. is there.

  By using the cement admixture and cement composition of the present invention, the strength development of cement concrete is improved.

Hereinafter, the present invention will be described in detail.
Parts and% in the present invention are based on mass unless otherwise specified.

The calcium sulfoaluminate used in the present invention (hereinafter referred to as CS aluminate) is, for example, a kiln or the like using a calcareous raw material such as lime, a sulfate raw material such as gypsum, and an alumina raw material such as bauxite as a raw material. It is manufactured by firing at about 1500 ° C. and pulverization.
The CS aluminate is not particularly limited, and for example, there is a material obtained by blending, firing, and pulverizing raw materials at a molar ratio of CaO: Al ₂ O ₃ : CaSO ₄ of 3: 3: 1. This is called Auin (3CaO.3Al ₂ O ₃ .CaSO ₄ ). Moreover, the expansion material (For example, Denka CSA # 20 by Denki Kagaku Kogyo KK) containing commercially available Auin can be used.
Blaine specific surface area value of CS aluminate (hereinafter referred to as Blaine value) is preferably not less than ^{4000cm 2 / g, 6000cm 2 /} g or more is more preferable. If it is less than 4000 cm ² / g, strength enhancement may not be expected.

  As the formate, acetate, and lactate (hereinafter referred to as formate) used in the present invention, specifically, sodium salt, potassium salt, calcium salt, magnesium salt barium salt, aluminum salt of formic acid, acetic acid and lactic acid, Zinc salt, ammonium salt, etc. are mentioned.

The silica fine powder used in the present invention is a general term for fine powders of substances having a siliceous main component and latent hydraulic properties, and is not particularly limited. For example, silica fume, silica dust, diatomaceous earth , Diatomaceous earth, fly ash, fine powder such as blast furnace slag, and the like, and one or more of these can be used in the present invention. The particle size of the fine silica powder is a 4000 cm ² / g or more in Blaine value is preferably at least ^{6000cm 2 / g, 8000cm 2 /} g or more is more preferable. If it is less than 4000 cm ² / g, sufficient strength expression may not be obtained.

The amount of each component used in the cement admixture of the present invention is not particularly limited, but when the cement admixture is composed of CS aluminate and formates, from the viewpoint of strength enhancement, the amount of CS aluminate used is 50-95 parts are preferable in 100 parts of cement admixture, more preferably 70-80 parts, and the amount of formate used is preferably 5-50 parts, more preferably 20-30 parts. Also, the cement admixture is CS aluminum. From the viewpoint of enhancing strength, the amount of CS aluminate used is preferably 20 to 70 parts in 100 parts of cement admixture, more preferably 30 to 60 parts, and use of formates. The amount is preferably 5 to 30 parts, more preferably 10 to 20 parts, and the amount of silica fine powder used is preferably 20 to 70 parts, more preferably 30 to 60 parts.

  The amount of the cement admixture is not particularly limited, but when the cement admixture is CS aluminate and formates, from the viewpoint of strength enhancement, in 100 parts of the binder consisting of cement and cement admixture, 2-6 parts are preferable and 4-6 parts are more preferable. Moreover, when a cement admixture consists of CS aluminate, formates, and a silica fine powder, 4-12 parts are preferable in 100 parts of binders, and 8-12 parts are more preferable from a viewpoint of intensity | strength improvement.

  Here, the cement is not particularly limited, and ordinary cement can be used. Specifically, various portland cements such as normal, early strength, super early strength, low heat, and moderate heat, and these portland cements can be used. In addition, various mixed cements mixed with blast furnace slag, fly ash, or silica, filler cement mixed with limestone powder or blast furnace slow-cooled slag fine powder, waste-use type cement, so-called eco cement, etc. 1 type or 2 types or more can be used together.

  In the present invention, in addition to cement, cement admixture, aggregates such as sand and gravel, water reducing agent, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent, AE agent, thickener, etc. One or two or more kinds can be used in combination as long as the object of the present invention is not impaired.

  As the mixing device for the cement admixture and cement composition of the present invention, any existing stirring device can be used, for example, a tilting barrel mixer, an omni mixer, a V-type mixer, a Henschel mixer, and a Nauta mixer can be used. . Moreover, mixing may mix each material at the time of construction, and may mix part or all beforehand.

  Hereinafter, the present invention will be described in detail by way of examples.

"Experiment 1"
A cement admixture prepared by blending CS aluminate and formates A as shown in Table 1 was blended in 100 parts of a binder composed of cement and cement admixture to prepare a binder. Further, a cement admixture prepared by blending calcium aluminate and formates A as shown in Table 1 was mixed with 4 parts in 100 parts of a binder composed of cement and cement admixture to prepare a binder. . Unit amounts of various materials in the concrete binder 465kg / ^{m 3,} sand 781kg / ^{m 3,} gravel 975 kg / ^{m 3,} water 165 kg / ^{m 3,} the concrete is prepared, the .phi.10 × 20 cm using the concrete A specimen was prepared, and the compressive strength at each age was measured according to JIS A 1108. The results are also shown in Table 1.

<Materials used>
CS aluminate: crystalline 3CaO.3Al ₂ O ₃ .CaSO ₄ (auin), loss on ignition of 1.0%, brain value of 6000 cm ² / g
Calcium aluminate (CA): crystalline CaO · _Al 2 _{O 3,} ignition loss 1.0%, Blaine value 5000 cm ² / g
Formates A: calcium formate, reagent grade 1 cement manufactured by Kanto Chemical Co .: ordinary Portland cement, commercial product, specific gravity 3.16
Fine aggregate: natural sand from Himekawa, Niigata Prefecture, specific gravity 2.62
Coarse aggregate: Crushed stone from Himekawa, Niigata Prefecture, maximum size 20mm, specific gravity 2.64

"Experimental example 2"
The experiment was conducted in the same manner as in Experiment No. 1-5 in Experimental Example 1 except that the formates shown in Table 2 were used. The results are also shown in Table 2.

<Materials used> Reagents primary formates B: sodium formate formates C: potassium formate formates D: calcium lactate formates E: sodium lactate formates F: potassium lactate formates G: calcium acetate formates H: Equivalent mixture of formates A and formates D

"Experiment 3"
The same procedure as in Experiment No. 1-5 in Experimental Example 1 was conducted except that the amount of cement admixture in 100 parts of the binder was changed to the amount shown in Table 3. The results are also shown in Table 3.

"Experimental example 4"
A cement admixture was prepared by blending CS aluminate, formates A and silica fume as shown in Table 4, and the same as in Experimental Example 1 except that the cement admixture in 100 parts of the binder was 8 parts. went. The results are also shown in Table 4.

<Materials used>
Silica fume: commercial product, brain value 8740 cm ² / g

“Experimental Example 5”
As shown in Table 5, the experiment was conducted in the same manner as in Experiment No. 4-4 in Experimental Example 4 except that the formates of Experimental Example 2 were used. The results are also shown in Table 5.

"Experimental example 6"
The same procedure as in Experiment No. 4-4 in Experimental Example 4 was performed except that the cement admixture in 100 parts of the binder was changed to the amount shown in Table 6. The results are also shown in Table 6.

"Experimental example 7"
The test was performed in the same manner as in Experiment No. 1-5 in Experimental Example 1 except that the brane value of CS aluminate was as shown in Table 7. The results are also shown in Table 7.

"Experimental example 8"
The test was performed in the same manner as in Experiment No. 4-4 in Experimental Example 4 except that the brane value of CS aluminate was as shown in Table 8. The results are also shown in Table 8.

  By using the cement admixture and the cement composition of the present invention, the strength development of cement concrete is improved, so that it can be widely applied in the civil engineering and construction fields.

Claims (3)

A cement admixture containing a calcium sulfoaluminate having a Blaine specific surface area value of 4000 cm ² / g or more and one or more selected from the group consisting of formate, acetate and lactate.   The cement admixture according to claim 1, further comprising silica fine powder.   A cement composition comprising the cement admixture according to claim 1 or 2 and cement.