JP4115767B2 - Cement admixture and cement composition - Google Patents

Description

【００４３】
実験例２
表２に示す量のγ-Ｃ_２Ｓ、表２に示す種類と量の硝酸塩類、及びγ-Ｃ_２Ｓと硝酸塩類ア１００部に対して遅延剤Ａ０．５部混合したセメント混和材を混合し、セメント９０部及び該セメント混和材１０部からなるセメント組成物１００部中としたこと以外は、実験例１と同様に試験した。結果を表２に併記する。
【００４４】
＜使用材料＞
硝酸塩類イ：市販品、亜硝酸カリウム
硝酸塩類ウ：市販品、硝酸リチウム
硝酸塩類エ：硝酸塩類アと硝酸塩類イの1：1混合物
【００４５】
【表２】

【００４６】
実験例３
γ-Ｃ_２Ｓ７０部、硝酸塩類ア３０部、及び表３に示す種類と量の遅延剤からなるセメント混和材を混合し、セメント９０部及び該セメント混和材１０部からなるセメント組成物を用いて流動保持率を評価したこと以外は、実験例１と同様に試験した。結果を表３に併記する。
【００４７】
＜使用材料＞
遅延剤Ｂ：市販品、グルコン酸
遅延剤Ｃ：市販品、グルコン酸ナトリウム
遅延剤Ｄ：市販品、酒石酸
遅延剤Ｅ：遅延剤Ａと遅延剤Ｄの１：１の混合物
【００４８】
＜試験方法＞
流動保持率：環境温度２０℃でのフロー値の経時変化にて評価した。JIS R 5201のフロー試験に準拠し、練り直後と６０分経過後のフロー値から算出した。
【００４９】
【数１】

【００５０】
【表３】

注：遅延剤の使用量は、γ-Ｃ_２Ｓと硝酸塩類アの合計を100部としたときの部。
【００５１】
実験例４
実験例１で作製したγ-Ｃ_２Ｓを粉砕して表４に示すブレーン比表面積値のγ-Ｃ_２Ｓ粉末を作製し、セメント90部及びセメント混和材10部からなるセメント組成物を使用したこと以外は実験例１と同様に試験した。結果を表４に併記する。
【００５２】
【表４】

【００５３】
【発明の効果】
本発明のセメント混和剤、及びセメント組成物を使用することにより、コンクリートの優れた初期強度発現性や中性化の抑制効果等の効果を奏するものであり、土木又は建築におけるコンクリート材料に適する。[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. The concrete in the present invention is a general term for cement paste, mortar, and concrete. In addition, the part used by this invention and% represent a mass unit.
[0002]
[Prior art and its problems]
Concrete is an excellent material that can build large structures at low cost. However, since the environment in which concrete is used in recent years has been diversified, durability against various deterioration factors in various environments has been demanded.
[0003]
One of the important causes of reducing the durability of concrete is neutralization. Degradation due to neutralization can occur in most environments. That is, neutralization is a phenomenon caused by the fact that calcium hydroxide reacts with carbon dioxide in the atmosphere and is carbonated.
[0004]
A problem caused by the neutralization of concrete is rust of reinforcing bars used as a reinforcing material, particularly in reinforced concrete structures. Due to the expansion pressure when rust is generated, the adhesion between the reinforcing bars and the concrete is impaired, and cracks are generated in the concrete, which may be one of the causes of reducing the strength of the concrete.
[0005]
Concrete structures built during the period of high economic growth in Japan are now required to be repaired against deterioration such as neutralization, and it is expected that more parts will need to be repaired in the future.
[0006]
As a repair method for deteriorated concrete, if it progresses to cracking due to neutralization, it must be repaired by removing the rust of the reinforcing bars by removing the rust and then placing concrete again. However, it is desired that the concrete used for the repair location has a large neutralization resistance or neutralization suppression effect from the viewpoint of life cycle cost.
[0007]
In such repair, a method has been proposed in which a cement composition made of cement and polymer is used to improve the adhesion to the repair surface and crack resistance, and to delay the progress of neutralization (Japanese Patent Laid-Open No. Hei 5-). No. 24899, etc.), since the cement composition does not have a neutralization-inhibiting effect, it has not yet led to the recurrence prevention of the neutralization of concrete after once repaired.
[0008]
Further, in the repair of arterial roads and the like, in order to alleviate traffic congestion, early completion of construction is strongly desired, and a material having rapid hardening is required.
For these reasons, the development of admixtures for repair materials that have both rapid hardening and neutralization suppression effects has been awaited.
[0009]
In view of the above situation, the present inventors have obtained the knowledge that the use of a specific cement admixture or a specific cement composition can impart a neutralization inhibiting effect and rapid hardening to concrete. It came to complete.
[0010]
[Means for Solving the Problems]
That is, the present invention is a cement admixture comprising a substance containing γ-C ₂ S or γ-C ₂ S having a Blaine specific surface area value of 2,000 cm ² / g or more, and nitrite and / or nitrate . The cement admixture containing a retarder, and a cement composition comprising cement and the cement admixture.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0012]
Γ-C ₂ S of the present invention is a non-hydraulic compound obtained by mixing and heat-treating a CaO raw material such as calcium carbonate and a SiO ₂ raw material such as silica, and has a chemical formula of 2CaO · SiO ₂ . This compound has a plurality of polymorphs such as α-type and β-type having hydraulic properties, and γ-C ₂ S of the present invention is called γ-type.
[0013]
Although the heat processing temperature is not specifically limited, Usually, it is about 1,200-1800 degreeC. The cooling method is not particularly limited. Although rapid cooling is not preferable, special slow cooling is not necessary, and natural cooling is sufficient.
[0014]
The presence of impurities is not particularly limited, and β-type C ₂ S, tricalcium silicate C ₃ S, lankynite C ₃ S ₂ and wollastonite CS may be mixed.
[0015]
As a substance containing γ-C ₂ S, various slags may be used in addition to the above-described synthetic product. Specific examples thereof include electric furnace reduction period slag, stainless steel slag, and the like molten iron pretreatment slag.
[0016]
However, these electric furnace reduction period slag, stainless steel slag, even molten iron pretreatment slag, the effect of the present invention for those not contain gamma-C2S is not obtained, gamma-C2S of the present invention Not suitable as a substance containing
[0017]
The materials containing gamma-C _{2 S,} the synthetic gamma-C _{2 S,} scan Tenresusuragu, molten iron pretreatment slag is available inexpensively, preferred.
[0018]
SiO ₂ as a component of these slags, CaO, Al ₂ O _3, and MgO and the like as the major chemical component, _{other, TiO 2, MnO, Na 2} O, S, P 2 O 5, and Fe ₂ O ₃ Etc.
[0019]
The compound, mainly a gamma-C _{2 S,} tri-calcium silicate 3CaO · SiO _2, rankinite night 3CaO · 2SiO _2, and calcium silicates, such as wollastonite CaO · SiO _2, etc. 2CaO · Fe ₂ O ₃ calcium ferrite, calcium aluminate such as 12CaO · 7Al ₂ O _3, a mixed crystal of gehlenite _{2CaO · Al 2 O 3 · SiO} 2 and Akerumanaito 2CaO · MgO · 2SiO _2, a main component a so-called melilite, Merubinaito 3CaO・ MgO ・ 2SiO ₂ , Calcium magnesium silicate such as Monticellite CaO ・ MgO ・ SiO ₂ , Anorthite CaO ・ Al ₂ O ₃・ 2SiO ₂ , 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 sulfides such as calcium sulfide CaS and iron sulfide FeS may be included.
[0020]
The amount of the material containing the _{γ-C 2} S or _{γ-C 2} S of the present invention is not particularly limited, in 100 parts of cement admixture, preferably 30 to 95 parts, more preferably 50 to 80 parts. If it is less than 30 parts, the neutralization suppressing effect may not be obtained, and if it exceeds 95 parts, excellent rapid hardening may not be obtained.
[0021]
The particle size of the material containing γ-C _{2 S} or γ-C _{2 S} is not particularly limited but is preferably 2,000 cm ² / g or more in Blaine specific surface area value, 3,500cm ² / g~8,000cm ² / g is more preferably, 4,000cm ² / g~7,000cm ² / g it is most preferred. If the Blaine specific surface area value is less than 2,000 cm ² / g, the neutralization suppressing effect is not sufficient, and the material separation resistance cannot be obtained. On the other hand, if it exceeds 8,000 cm ² / g, excessive pulverization power is required, which causes an increase in cost.
[0022]
Nitrite and / or nitrate (hereinafter referred to as nitrates) used in the present invention imparts rapid hardening by mixing with cement and is not particularly limited. Specifically, nitrite and nitrate are used. The alkali metal salts or alkaline earth metal salts of these are mentioned, and among them, the use of lithium salts, sodium salts, potassium salts, and calcium salts is economically preferable. In the present invention, one or more of these can be used, but lithium salts and calcium salts are more preferable from the point of not promoting the alkali-aggregate reaction, particularly when lithium nitrite is used, Rapid hardening is most prominent and most preferred.
[0023]
Although the usage-amount of nitrate is not specifically limited, 5-70 parts are preferable in 100 parts of cement admixtures, and 20-50 parts are more preferable. If it is less than 5 parts, the predetermined rapid hardening may not be obtained, and if it exceeds 60 parts, the fluidity of the concrete may be lost rapidly and construction may be difficult.
[0024]
Although the retarder used in the present invention is not particularly limited, it is for adjusting the setting of cement and not impairing the fluidity of concrete during construction, and both organic and inorganic substances can be used.
[0025]
As specific examples of organic substances, organic acids such as carboxylic acids, oxymonocarboxylic acids, oxypolycarboxylic acids, and polycarboxylic acids or salts thereof can be used.
[0026]
Specific examples of the carboxylic acid include saturated or unsaturated carboxylic acids such as succinic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, and heptanoic acid. Examples of the acid include heptonic acid, gluconic acid, and glycolic acid.
[0027]
Examples of the oxypolyvalent carboxylic acid include malic acid, tartaric acid, and citric acid, and examples of the polycarboxylic acid include cocondensates such as acrylic acid and maleic anhydride.
[0028]
In addition, salts of the above organic acids can also be used, for example, alkali metals such as lithium, sodium and potassium, alkaline earth metal salts such as magnesium and calcium, and zinc, copper, aluminum and ammonium. Examples include salts.
[0029]
Specific examples of inorganic substances include inorganic acids such as phosphoric acid and hydrofluoric acid, phosphates, zinc oxide, lead oxide, boric acid, silicofluorides such as magnesium fluorosilicate and sodium fluorosilicate, and ice. Fluorine-containing minerals such as crystallite and calcium fluoroaluminate can be used.
[0030]
In the present invention, one or more of these can be used, and it is particularly preferable to use citric acid or a salt thereof, gluconic acid or a salt thereof, and tartaric acid or a salt thereof.
[0031]
Although the usage-amount of a retarder is not specifically limited, 0.1-10 parts are preferable in 100 parts of cement admixtures, and 0.3-5 parts are more preferable.
[0032]
The amount of the cement admixture of the present invention is not particularly limited, but usually 3 to 20 parts is preferable and 7 to 15 parts is preferably 100 parts by weight of cement composition composed of cement and cement admixture. More preferred. If it is less than 3 parts, the effects of the present invention may not be sufficiently obtained, and if it is used in excess of 20 parts, long-term strength development may be impaired.
[0033]
Although the cement used in the present invention is not particularly limited, it is preferable to use a cement containing Portland cement. For example, various portland cements such as normal, early strength, super early strength, low heat, or moderate heat, and blast furnaces for these portland cements are used. Examples include various mixed cements obtained by mixing granulated slag, fly ash, or silica, or limestone filler cement obtained by mixing limestone powder with Portland cement.
[0034]
Further, in the present invention, it is also possible to mix fine aggregate with cement and a cement composition comprising the cement admixture of the present invention, and the type of fine aggregate is not particularly limited, for example, lime sand, silica sand, River sand, sea sand, mountain sand, crushed sand and the like can be used, and the maximum particle size is preferably 5 mm or less, more preferably 2.5 mm or less.
[0035]
In the present invention, the cement admixture and the cement composition of the present invention include a water reducing agent, an AE water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent, an antifoaming agent, an increase in addition to aggregates such as sand and gravel. One or two of sticky agent, rust preventive agent, antifreeze agent, expansion material, shrinkage reducing agent, polymer emulsion, setting modifier, clay mineral such as bentonite and zeolite, ion exchanger such as hydrotalcite, etc. The above can be used as long as the object of the present invention is not substantially impaired.
[0036]
The amount of water used in the present invention is preferably 20 to 60 parts of water with respect to 100 parts of cement. If the amount of water is less than 20 parts, the fluidity may be insufficient. If the amount exceeds 60 parts, the strength may be insufficient.
[0037]
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. Any existing apparatus can be used as the mixing apparatus, and for example, a tilting cylinder mixer, an omni mixer, a Henschel mixer, a V-type mixer, a Nauter mixer, and the like can be used.
[0038]
【Example】
Hereinafter, description will be made based on experimental examples of the present invention.
[0039]
Experimental example 1
70 parts of γ-C ₂ S pulverized to a Blaine specific surface area value of 4,000 cm ² / g, 30 parts of nitrates, and 0.5 parts of retarder A to a total of 100 parts of γ-C ₂ S and nitrates Mixed and mixed as a cement admixture. Further, using the cement admixture with the composition shown in Table 1 and a cement composition with the balance being 100 parts as a cement, a mortar having a water / cement composition ratio = 50% and a cement composition / sand ratio = 1/3 was prepared. Then, the compressive strength and the neutralization depth at the age of 1 day and 28 days were measured. The results are also shown in Table 1.
[0040]
<Materials used>
Cement: Commercial product, ordinary Portland cement γ-C ₂ S: Raw material obtained by mixing and grinding 2 mol of calcium carbonate and 1 mol of silicon dioxide in an electric furnace at 1500 ° C. for 3 hours, then taken out of the furnace and cooled. And synthesized. γ-C ₂ S was pulverized (dusted) to become a coarse powder having a brain specific surface area value of 1,800 cm ² / g, and the coarse powder was pulverized to obtain a powder having a brain specific surface area value of 4,000 cm ² / g.
Nitrate A: Commercial product, lithium nitrite retarder A: Commercial product, citric acid water: Tap water fine aggregate: ISO679 compliant, standard sand [0041]
<Measurement method>
Compressive strength: 4 × 4 × 16 cm specimens were prepared, and the strength at 1 day of material and 28 days of material was measured according to JIS A 1108. Casting temperature 20 ° C.
Neutralization depth: 4 x 4 x 16 cm specimens are prepared and cured in water at 20 ° C until the age of 28 days, and then promoted in an environment of 30 ° C, relative humidity 60% and carbon dioxide concentration 10% It became sex. Six months later, the specimen was cut into pieces, a phenolphthalein solution was applied to the cross section, the neutralization depth from the surface to the colored part was measured, and the neutralization inhibitory effect was evaluated.
[0042]
[Table 1]

[0043]
Experimental example 2
The amounts shown in Table 2 gamma-C _{2 S,} type and amount of nitrates in Table 2, and gamma-C _{2 S} and nitrates cement admixture obtained by mixing A0.5 parts retarder against A 100 parts of a The test was conducted in the same manner as in Experimental Example 1, except that the mixture was mixed in 100 parts of a cement composition composed of 90 parts of cement and 10 parts of the cement admixture. The results are also shown in Table 2.
[0044]
<Materials used>
Nitrate A: Commercial product, Potassium nitrite Nitrate C: Commercial product, Lithium nitrate Nitrate d: A 1: 1 mixture of Nitrate a and Nitrate a
[Table 2]

[0046]
Experimental example 3
70 parts of γ-C ₂ S, 30 parts of nitrates, and a cement admixture comprising the types and amounts of retarders shown in Table 3 are mixed, and a cement composition comprising 90 parts of cement and 10 parts of the cement admixture is used. The test was conducted in the same manner as in Experimental Example 1 except that the fluid retention was evaluated. The results are also shown in Table 3.
[0047]
<Materials used>
Retarder B: commercial product, gluconic acid retarder C: commercial product, sodium gluconate retarder D: commercial product, tartaric acid retarder E: 1: 1 mixture of retarder A and retarder D
<Test method>
Flow retention: The flow rate at an environmental temperature of 20 ° C. was evaluated with the passage of time. Based on the flow test of JIS R 5201, it was calculated from the flow value immediately after kneading and after 60 minutes.
[0049]
[Expression 1]

[0050]
[Table 3]

Note: The amount of retarder used is the part when the total of γ-C ₂ S and nitrates is 100 parts.
[0051]
Experimental Example 4
The γ-C ₂ S produced in Experimental Example 1 was pulverized to produce γ-C ₂ S powder having the Blaine specific surface area values shown in Table 4, and a cement composition comprising 90 parts of cement and 10 parts of cement admixture was used. The test was performed in the same manner as in Experimental Example 1 except that. The results are also shown in Table 4.
[0052]
[Table 4]

[0053]
【The invention's effect】
By using the cement admixture and the cement composition of the present invention, the concrete exhibits excellent initial strength development and neutralization suppression effects, and is suitable for concrete materials in civil engineering or construction.

Claims (3)

A cement admixture comprising a substance containing γ-C ₂ S or γ-C ₂ S having a brain surface area value of 2,000 cm ² / g or more, and nitrite and / or nitrate . Cement admixture comprising a retarder according to claim 1 Symbol placement. The cement composition comprising a cement admixture according to one of the cement and claims 1 2.