JP4131795B2 - Cement admixture and cement composition - Google Patents

Description

【００２６】
表１から、本発明のセメント混和材を使用したセメント組成物は、優れた寸法安定性と中性化抑制効果を示すことが判る。
【００２７】
実験例２
γ−２ＣａＯ・ＳｉＯ₂５０部と、膨張物質Ａ５０部とからなるセメント混和材をセメント組成物１００部中、１５部使用し、γ−２ＣａＯ・ＳｉＯ₂の粒度を表２に示すように変えたこと以外は、実施例１と同様に行った。結果を表２に併記する。
【００２８】
【表２】

【００２９】
表２から、本発明のセメント混和材の成分であるγ−２ＣａＯ・ＳｉＯ₂の粒度を細かくすると優れた中性化抑制効果を示す傾向にあることが判る。
【００３０】
実験例３
ブレーン比表面積４０００ｃｍ²／ｇのγ−２ＣａＯ・ＳｉＯ₂を使用し、表３に示すような膨張物質を使用してセメント混和材を調製し、セメント組成物１００部中、セメント混和材を１５部使用したこと以外は、実施例１と同様に行った。結果を表３に併記する。
【００３１】
＜使用材料＞
膨張物質Ｂ：電気化学工業社製「デンカＣＳＡ＃２０」、遊離石灰−水硬性化合物−無水セッコウ系、ブレーン比表面積２８００ｃｍ²／ｇ。遊離石灰量２０％
膨張物質Ｃ：太平洋マテリアル社製「エクスパン構造用」、遊離石灰−水硬性化合物−無水セッコウ系、ブレーン比表面積３５００ｃｍ²／ｇ。遊離石灰量３３％。
【００３２】
【表３】

【００３３】
表３から、本発明のセメント混和材の成分である膨張物質の種類を変えても、優れた中性化抑制効果を示すことが判る。
【００３４】
実験例４
ブレーン比表面積４０００ｃｍ²／ｇのγ−２ＣａＯ・ＳｉＯ₂５０部と膨張物質Ａ５０部からなるセメント混和材をセメント組成物１００部中、１５部使用し、セメントの種類を表４に示すように変えたこと以外は、実施例１と同様に行った。結果を表４に併記する。
【００３５】
＜使用材料＞
セメント（ロ）：市販の高炉セメントＢ種、ブレーン比表面積４０００ｃｍ²／ｇ、比重３．０６
セメント（ハ）：市販の高炉セメントＣ種、ブレーン比表面積４５００ｃｍ²／ｇ、比重２．９８
【００３６】
【表４】

【００３７】
表４から、本発明のセメント混和材を使用したセメント組成物は、優れた寸法安定性と中性化抑制効果を示すことが判るが、特に高炉セメントに対して、著しい効果を示すことが判る。
【００３８】
【発明の効果】
本発明のセメント混和材を使用することにより、寸法安定性と中性化抑制効果を付与でき、特に高炉セメントに用いると有益である等の効果を奏する。[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a cement admixture and a cement composition used in the civil engineering and construction industries.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.
[0002]
[Prior art]
Recently, the durability of concrete has been greatly highlighted, and its reliability is regarded as important. For example, in order to reduce the crack of concrete and to make it a highly reliable concrete, the expansion | swelling material is utilized. This is because cracks are easily affected by neutralization, which is a deterioration factor of concrete. If cracks can be reduced, the effect of neutralization can be reduced, and a durable concrete structure can be constructed.
[0003]
[Problems to be solved by the invention]
However, this means that a sound concrete structure with few macroscopic defects is constructed, which is different from the carbon dioxide permeability of the concrete itself. That is, the permeation of carbon dioxide proceeds even through a more microscopic gap.
Therefore, it is desired that the concrete frame itself is made of a concrete that is difficult for carbon dioxide gas to permeate, after having a sound concrete structure with few macroscopic defects. That is, today, the development of a cement admixture that can impart an effect of suppressing neutralization as well as expansibility to concrete is awaited.
Thus, as a result of various studies, the inventor has found that the cement admixture composed of γ-2CaO · SiO ₂ and an expansion material imparts both expansion and neutralization suppression, and thus completes the present invention. It came to do.
[0004]
[Means for Solving the Problems]
That is, the present invention contains 20 to 80 parts of γ-2CaO · SiO _{2 and} 80 to 20 parts of expanding material in a total of 100 parts of γ-2CaO · SiO ₂ and expanding material having a specific surface area of 3000 cm ² / g or more. A cement admixture comprising the cement and the cement admixture, wherein the amount of free lime of the expansion material exceeds 40%. Furthermore, the cement composition is characterized in that the cement is a blast furnace cement.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0006]
Among the compounds represented by 2CaO · SiO ₂ , γ-2CaO · SiO ₂ used in the present invention is known as a low temperature phase, and α-2CaO · SiO ₂ and β-2CaO. It is different from SiO ₂ . These are both 2CaO · SiO ₂ and have the same chemical composition, but their crystal structures are different. Usually, 2CaO · SiO ₂ present in the cement clinker is β-2CaO · SiO ₂ . Although β-2CaO · SiO ₂ has hydraulic properties, it does not show the effect of inhibiting neutralization like γ-2CaO · SiO ₂ of the present invention.
[0007]
Blaine specific surface area of γ-2CaO · SiO ₂ is preferably ^{3000~8000cm 2 / g, 4000~6000cm 2 /} g is more preferable. If the Blaine specific surface area is less than 3000 cm ² / g, the neutralization suppressing effect may not be sufficiently obtained.
[0008]
Impurities are included when industrially producing γ-2CaO · SiO ₂ of the present invention, but the presence thereof is not particularly limited, and is not particularly problematic as long as the object of the present invention is not substantially inhibited. . Specific examples thereof include Al ₂ O ₃ , MgO, TiO ₂ , MnO, Na ₂ O, S, Cr ₂ O ₃ , P ₂ O ₅ and Fe ₂ O ₃ .
[0009]
The compound coexist, gamma-2CaO · and other than SiO ₂ Dicalcium silicate, tri-calcium silicate 3CaO · SiO _2, rankinite night _{3CaO · 2SiO 2, 2CaO · SiO} 2 other than such wollastonite CaO · SiO ₂ calcium silicate, Meruvi night 3CaO · MgO · 2SiO _2, Akerumanaito 2CaO · MgO · 2SiO _2, calcium magnesium silicate, such as Monte celite CaO · MgO · SiO _2, gehlenite _{2CaO · Al 2 O 3 · SiO} 2, anorthite CaO · calcium aluminosilicate, such as Al ₂ O ₃ · 2SiO _2, and Akerumanaito 2CaO · a MgO · 2SiO ₂ and gehlenite _{2CaO · Al 2 O 3 · SiO} 2 mixed crystals melilite, MgO · SiO ₂ and 2MgO · S Magnesium silicates such as O _2, free lime, free magnesia, calcium ferrite 2CaO · Fe ₂ O _3, calcium aluminosilicate ferrite _{4CaO · Al 2 O 3 · Fe} 2 O 3, leucite _{(K 2 O, Na 2 O} ) · Al ₂ O ₃ .SiO ₂ , spinel MgO.Al ₂ O ₃ , magnetite Fe ₃ O _{4 and the} like may be included.
[0010]
The expansion material according to the present invention is not particularly limited, and any material can be used. Broadly divided, there are gas foam materials and cement minerals. Specific examples thereof include, for example, aluminum powder, iron powder, a peroxide material, and a carbon material in a gas foam material system. Moreover, in a cement mineral type | system | group, expansion materials, such as an ettringite type | system | group, a lime type | system | group, and a lime-ettringite composite type | system | group, are mentioned. In the present invention, it is preferable to use a cement mineral system from the viewpoint of imparting effective expansibility.
[0011]
The cement mineral expansion material will be described in more detail. Examples of the cement mineral-based expansion material include those containing free lime and free magnesia, but those containing free lime are preferred from the viewpoint of long-term stability. As what contains free lime, a free lime-anhydrous gypsum system, a free lime-hydraulic compound system, a free lime-hydraulic compound-anhydrogypsum system etc. are mentioned, for example. In the present invention, it is preferable to use a free lime-hydraulic compound-anhydrous gypsum system because of its good expansion performance, and those having a free lime content exceeding 40% are particularly preferable. Here, examples of the hydraulic compound include one or more of Auin, calcium ferrite, calcium aluminoferrite, calcium silicate, calcium aluminate, and the like. As such an expanding material, a commercially available expanding material or a static crushing material can be used.
[0012]
Expandable materials and static crushed materials are commercially available from various companies, and representative examples thereof include, for example, “Denka CSA”, “Denka Power CSA” manufactured by Denki Kagaku Kogyo Co., Ltd. “Sachs” manufactured by Taiheiyo Materials Co., Ltd., “Expan”, “N-EX”, “Breister” manufactured by Taiheiyo Materials Co., Ltd., and the like.
[0013]
The blending ratio of γ-2CaO · SiO ₂ and the expansion material in 100 parts of the cement admixture in the present invention varies depending on the application and is not particularly limited, but is preferably 20 to 80 parts, and 40 to 60 parts, respectively. More preferred. If γ-2CaO · SiO ₂ exceeds 80 parts or the expansion material is less than 20 parts, sufficient dimensional stability may not be obtained. On the contrary, if γ-2CaO · SiO ₂ is less than 20 parts or the expansion material exceeds 80 parts, the neutralization suppressing effect may not be sufficiently obtained.
[0014]
Moreover, the usage-amount of the cement admixture of this invention changes with uses, and is not specifically limited, Usually, 5-30 parts are preferable in 100 parts of cement compositions, and 10-20 parts are more preferable. If the amount is less than 5 parts, the effects of the present invention, that is, the neutralization suppressing effect and dimensional stability may not be sufficiently imparted, and even if the amount exceeds 30 parts, further enhancement of the effect cannot be expected.
[0015]
As the cement used in the present invention, various portland cements such as normal, early strength, super early strength, low heat and moderate heat, various mixed cements obtained by mixing blast furnace granulated slag, fly ash, or silica with these portland cements, Moreover, the filler cement etc. which mixed the limestone powder etc. are mentioned, Among these, the 1 type (s) or 2 or more types can be used.
The cement admixture of the present invention is particularly useful when used for blast furnace cement which is easily neutralized and has low cracking resistance.
[0016]
In the cement composition of the present invention, the respective materials may be mixed at the time of construction, or a part or all of them may be mixed in advance.
[0017]
The particle size of the cement composition of the present invention is not particularly limited since it depends on the purpose and application to be used, usually, preferably 3000~8000cm ² / g in Blaine specific surface area, 4000~6000cm ² / g is More preferred. If it is less than 3000 cm ² / g, sufficient strength development may not be obtained, and if it exceeds 8000 cm ² / g, workability may deteriorate.
[0018]
In the present invention, in addition to cement, the present admixture, aggregates such as sand and gravel, water reducing agent, AE water reducing agent, high performance water reducing agent and high performance AE water reducing agent, blast furnace granulated slag fine powder, blast furnace slow cooling Additives such as slag fine powder, limestone fine powder, fly ash and silica fume, hardeners, antifoaming agents, thickeners, rust preventives, antifreeze agents, shrinkage reducing agents, polymers, setting modifiers, bentonites, etc. One or more of clay minerals and anion exchangers such as hydrotalcite can be used within a range that does not substantially impair the object of the present invention.
[0019]
In the present invention, the mixing method of each material is not particularly limited, and the respective materials may be mixed at the time of construction, or a part or all of them may be mixed in advance.
[0020]
Any existing device can be used as the mixing device, and for example, a tilting barrel mixer, an omni mixer, a Henschel mixer, a V-type mixer, a Nauta mixer, and the like can be used.
[0021]
【Example】
Hereinafter, further description will be given based on experimental examples of the present invention.
[0022]
Experimental example 1
And γ-2CaO · SiO ₂ 50 parts of Blaine specific surface area of 4000 cm ² / g, was blended with the inflation material A50 parts to prepare a cement admixture. Using this cement admixture, the amount of cement admixture used in 100 parts of the cement composition consisting of cement and cement admixture is used in the proportions shown in Table 1, and the water / cement composition ratio is 50%. Mortar with a composition to sand ratio of 1: 3 was prepared.
The prepared mortar was measured for compressive strength, rate of change in length, and neutralization depth. For comparison, the same procedure was performed when limestone fine powder was used instead of γ-2CaO · SiO ₂ . The results are also shown in Table 1.
[0023]
<Materials used>
Cement (I): Commercially available ordinary Portland cement, Blaine specific surface area 3200 cm ² / g, specific gravity 3.15
γ-2CaO.SiO ₂ : 2 moles of reagent grade calcium carbonate and 1 mole of silicon dioxide were mixed and pulverized, then fired at 1450 ° C. for 3 hours in an electric furnace, taken out of the furnace and cooled by natural cooling. And synthesized. At this time, dusting was performed and the powder was pulverized to a specific surface area of 1800 cm ² / g. This was further pulverized to the particle size shown in Table 1.
Limestone fine powder: pulverized limestone from Aomi mine, Niigata Prefecture, Blaine specific surface area 4000 cm ² / g.
Expansion material A: “Denka Power CSA” manufactured by Denki Kagaku Kogyo Co., Ltd., free lime-hydraulic compound-anhydrous gypsum system, Blaine specific surface area 2900 cm ² / g. Free lime content 50%
Sand: JIS standard sand (ISO679 compliant)
Water: Tap water [0024]
<Measurement method>
Blaine specific surface area: Measured according to JIS R 5201.
Compressive strength: A 4 × 4 × 16 cm specimen was prepared, and the strength at 28 days of age was measured according to JIS R 5201.
Length change rate: Measured at a material age of 28 days in accordance with JIS A 6202. However, it was demolded at a material age of 1 day, and underwater curing was carried out until the material age was 7 days. Thereafter, air-drying curing was carried out at an environment of 20 ° C. and a relative humidity of 60% until the material age was 28 days.
Neutralization depth: 4 x 4 x 16 cm specimens were prepared and subjected to 20 ° C water curing until the age of 28 days, and then promoted in an environment of 30 ° C, relative humidity 60%, carbon dioxide concentration 5% After 8 weeks, the specimens were cut and the neutralization depth was confirmed by spraying a phenolphthalein alcohol solution on the cross section.
[0025]
[Table 1]

[0026]
From Table 1, it can be seen that the cement composition using the cement admixture of the present invention exhibits excellent dimensional stability and neutralization inhibiting effect.
[0027]
Experimental example 2
Cement admixture consisting of 50 parts of γ-2CaO · SiO _{2 and} 50 parts of expansion material A was used in 100 parts of cement composition, and the particle size of γ-2CaO · SiO ₂ was changed as shown in Table 2. Except that, the same procedure as in Example 1 was performed. The results are also shown in Table 2.
[0028]
[Table 2]

[0029]
From Table 2, it can be seen that when the particle size of γ-2CaO · SiO ₂ which is a component of the cement admixture of the present invention is made finer, it tends to show an excellent neutralization suppressing effect.
[0030]
Experimental example 3
Using γ-2CaO · SiO ₂ having a Blaine specific surface area of 4000 cm ² / g, a cement admixture was prepared using an expanding material as shown in Table 3, and 15 parts of the cement admixture in 100 parts of the cement composition. The same operation as in Example 1 was performed except that it was used. The results are also shown in Table 3.
[0031]
<Materials used>
Expansion material B: “Denka CSA # 20” manufactured by Denki Kagaku Kogyo Co., Ltd., free lime-hydraulic compound-anhydrous gypsum system, Blaine specific surface area 2800 cm ² / g. 20% free lime
Swelling material C: “For EXPANSE structure” manufactured by Taiheiyo Materials Co., Ltd., free lime-hydraulic compound-anhydrous gypsum system, Blaine specific surface area 3500 cm ² / g. Free lime amount 33%.
[0032]
[Table 3]

[0033]
From Table 3, it can be seen that even if the type of the expansion material that is a component of the cement admixture of the present invention is changed, an excellent neutralization suppressing effect is exhibited.
[0034]
Experimental Example 4
The cement admixture composed of an expansion material A50 parts γ-2CaO · SiO ₂ 50 parts of Blaine specific surface area of 4000 cm ² / g in 100 parts of cement composition, using 15 parts, changing the type of cement, as shown in Table 4 The procedure was the same as in Example 1 except that. The results are also shown in Table 4.
[0035]
<Materials used>
Cement (b): Commercial blast furnace cement type B, Blaine specific surface area 4000 cm ² / g, specific gravity 3.06
Cement (C): Commercial blast furnace cement type C, Blaine specific surface area 4500 cm ² / g, specific gravity 2.98
[0036]
[Table 4]

[0037]
From Table 4, it can be seen that the cement composition using the cement admixture of the present invention exhibits excellent dimensional stability and neutralization-inhibiting effect, but particularly shows remarkable effect on blast furnace cement. .
[0038]
【The invention's effect】
By using the cement admixture of the present invention, dimensional stability and neutralization-inhibiting effect can be imparted, and particularly advantageous when used for blast furnace cement.

Claims (4)

Cement admixture containing 20 to 80 parts of γ-2CaO · SiO _{2 and} 80 to 20 parts of expansion material in a total of 100 parts of γ-2CaO · SiO ₂ and expansion material having a specific surface area of 3000 cm ² / g or more. . Claim 1 Symbol placement cement admixture of the free lime content of the expanded material, characterized in that more than 40%. And cement, according to claim 1 cement composition comprising the cement admixture according to any one of 2. The cement composition according to claim 3 , wherein the cement is a blast furnace cement.