JP6801699B2 - Fast-hardening admixture for cement, its manufacturing method and quick-hardening cement composition - Google Patents

Description

The present invention relates to a quick-hardening admixture for cement, a method for producing the same, and a quick-hardening cement composition, and in particular, it can be added to any cement to impart good early strength development to the cement, and is sufficient. The present invention relates to a quick-hardening admixture for cement, a method for producing the same, and a quick-hardening cement composition, which secures a pot life and is excellent in workability.

In recent years, in the construction of tunnels and underground spaces, a spraying method has been widely implemented in which a cement mixture such as mortar or concrete is sprayed onto a wall surface or an exposed surface to line the surface to prevent the wall surface or the exposed surface from collapsing.
In such a concrete spraying method, concrete, etc. is prepared, the minimum usable time (handling time) required for handling it is secured, and after spraying on the wall surface or exposed surface, the concrete, etc. is immediately hardened. I need to let you.
In addition, it is necessary to secure the usable time of mortar and concrete and to cure it immediately even in water stoppage work and emergency work.

Conventionally, as a cement having a fast-hardening property, a hard-hardening cement such as a jet cement has been manufactured. As clinker used in these, there jet cement clinker, Erwin system clinker composed mainly of C4A3 S, alumina cement clinker or the like composed mainly of CA is.
There is also a method of obtaining amorphous C12A7 by melting a clinker containing C12A7, which is a rapid-hardening component, as a main component, and then quenching the clinker.

In particular, the conventional jet cement clinker is a clinker containing a calcium silicate phase as a main component and about 20 to 30% by weight of C11A7 / CaF2 as a fast-curing component, and is formed by generating a melt phase such as C11A7CaF2 or C4AF. Is. Therefore, if the content of C12A7, which is a rapid-hardening component, is set to the above range or more, the melt phase becomes too large and the clinker melts, which makes it very difficult to manufacture, for example, in the current equipment.

Further, the Irwin clinker is used as a clinker for hard-hardening cement because it contains 70% by weight or more of Irwin (C4A3 S ) having a hard-hardness, but due to the characteristics of the hard-hardening component, it is particularly at a low temperature. There is a problem that it is inferior in sharpness.
Further, the alumina cement clinker containing CA as a main component is inferior in rapid hardness to the clinker containing C12A7 as a main component.

Japanese Patent No. 3179702 (Patent Document 1) describes a clinker composition used for hard-hardening cement, quick-setting material, quick-hardening cement, ground improvement material, masking material, etc., and has 12CaO.7Al as a mineral phase. Low temperature by coexisting Fe ₂ O ₃ with 0.1 to 9% by weight of the whole and CaF ₂ with 0.1 to 9% by weight of the whole in a clinker raw material containing ₂ O ₃ calcium aluminate as a main component. The melt formation start temperature of the low temperature melt phase and the high temperature melt phase is lowered by forming a melt phase and a high temperature melt phase and adding 0.5 to 9% by weight of TiO ₂ to the whole. A hard-hardening clinker composition characterized by being fired is disclosed.
In this cement clinker, in order to promote the solid phase reaction, it is necessary to positively form a melt phase, and if the melt phase is small, the solid phase reaction does not proceed and the clinker mineral formation does not proceed well. On the other hand, excessive formation of the melt phase poses a problem in the production of clinker, so it is necessary to adjust the amount of the melt phase to be formed so as to fall within a certain range.
In particular, this clinker has a C12A7-based mineral content increased as compared with the jet clinker, and produces a C12A7-based mineral phase by a solid-phase reaction. At this time, Fe and Ti are added to generate an appropriate amount of melt phase to obtain a clinker.

Further, as a rapid-hardening material that promotes hardening of mortar and concrete, Japanese Patent Application Laid-Open No. 2005-060154 (Patent Document 2) states that (a) calcium aluminate particles coated with hydrate and (b) calcium sulfate. And (c) a hard-hardening material containing at least one selected from the group of aluminum sulfate, alkali metal sulfate, and alkali metal carbonate, and Portland cement or mixed cement, and the hard-hardening material. A hard-hardening cement composition is disclosed.

Further, Japanese Patent Application Laid-Open No. 2006-182568 (Patent Document 3) states that a desired relatively long pot life can be secured even after water injection by mixing with a hydraulic composition such as cement, mortar, and concrete. A hardened material containing calcium aluminate particles having a hydrate coating layer and quicklime and / or slaked lime is disclosed.

However, it cannot be said that these hard-hardening materials have sufficient pot life on site, and a new fast-hardening admixture that can secure sufficient pot life and has excellent early strength development is desired. ing.

Japanese Patent No. 3179702 Japanese Unexamined Patent Publication No. 2005-060154 Japanese Unexamined Patent Publication No. 2006-182568

An object of the present invention is to provide an admixture for cement which is a miscible material to be mixed with cement, which can secure a sufficient pot life and can impart early strength development, and a method for producing the same. ..
Further, another object of the present invention is a cement composition containing the cement admixture of the present invention, which is excellent in workability and excellent in early strength development because a sufficient pot life can be secured. To provide a cement composition.

The quick-hardening admixture for cement of the present invention contains a calcium aluminate material whose surface has been water-treated, boric acid, and gypsum, and boric acid is added to 100 parts by mass of the water-treated calcium aluminate material. It contains 1.2 to 1.8 parts by weight in contrast, gypsum, 4 at a mass ratio relative to the water treated calcium aluminate material: 6 to 6: included in a ratio of 4, characterized in Rukoto , A quick-hardening admixture for cement.
Preferably, the quick-hardening admixture for cement of the present invention is the quick-hardening admixture for cement, and the calcium aluminate material whose surface has been water-treated is 0 with respect to 100 parts by mass of the calcium aluminate powder. characterized in that it is surface-treated with .25～2 parts by weight of water, Ru der cement rapid hardening admixture.

The quick-hardening cement composition of the present invention is a fast-hardening cement composition, which comprises any of the above-mentioned quick-hardening admixtures for cement and cement.

In the method for producing a quick-hardening admixture for cement of the present invention, water-treated calcium aluminate powder is prepared by spraying 0.25 to 2 parts by mass of water on 100 parts by mass of calcium aluminate powder and mixing them. In the step of preparation, 1.2 to 1.8 parts by mass of boric acid was added to 100 parts by mass of the water-treated calcium aluminate powder, and water-treated calsim-aluminate powder and gypsum were added in a mass ratio of 4: It is a method for producing a quick-hardening admixture for cement, which comprises a step of adding and blending gypsum so as to have a ratio of 6 to 6: 4 and uniformly mixing the gypsum.

The quick-hardening admixture for cement of the present invention can secure a sufficient pot life for the quick-hardening cement composition of the present invention such as mortar obtained by mixing with an arbitrary cement, and has excellent workability. Can be obtained, and early strength development and excellent 3-hour early strength can be exhibited.
Therefore, it can be effectively applied at work sites and the like in hard-hardening applications, and further, by simply adjusting and adding an arbitrary amount of the quick-hardening admixture for cement of the present invention according to a desired initial strength, It becomes easy to carry out a design to obtain a desired sharp hardness, and it is possible to secure a sufficient pot life and improve workability.
The method for producing a quick-hardening admixture for cement of the present invention makes it possible to effectively manufacture the quick-hardening admixture for cement of the present invention.

The present invention will be described in the following form, but the present invention is not limited thereto.
The quick-hardening admixture for cement of the present invention is characterized by containing a water-treated calcium aluminate material whose surface has been treated with a predetermined amount of water, boric acid, and gypsum. Is.
Preferably, the quick-hardening admixture for cement of the present invention is the quick-hardening admixture for cement, and the calcium aluminate material whose surface is water-treated is 0 with respect to 100 parts by mass of the calcium aluminate powder. The surface is treated with 25 to 2 parts by mass of water, and more preferably, in the quick-hardening admixture for cement, boric acid is 1. With respect to 100 parts by mass of the water-treated calcium aluminate material. 2 to 1.8 parts by mass, gypsum is a fast-hardening admixture for cement contained in a ratio of 4: 6 to 6: 4 to the water-treated calcium aluminate material. ..

Calcium aluminate material used in cement for rapid hardening admixture of the present invention is a material for the CaO and Al ₂ O ₃ as a main chemical component is not limited as long as it has a hydrating activity, for example, chemical components mineral composition include those such as _{12CaO · 7Al 2 O 3, CaO} · Al 2 O 3, 3CaO · Al 2 O 3, 11CaO · 7Al 2 O 3 · CaF 2, 4CaO · 3Al 2 O 3 · SO 3 as It is possible that two or more of these types coexist, or alumina cement may be used.

In particular, in order to more effectively exhibit the above effects of the present invention, the calcium aluminate material is preferably a C12A7-based calcium aluminate material, and C12A7 containing 70% by mass or more, preferably 83% by mass or more of a C12A7-based mineral phase. A calcium aluminate-based material can be preferably used.
When the content of the C12A7-based mineral phase contained in the calcium aluminate material is 70% by mass or more, the above-mentioned effect of the present invention can be more exhibited.

C12A7 and C11A7 / CaX ₂ (X is a halogen such as F, Cl, Br) correspond to the calcium aluminate phase contained in such a suitable C12A7-based calcium aluminate material, and a mixed phase thereof. You may.
Further, it is desirable that the suitable C12A7-based calcium aluminate material does not substantially contain Irwin.

The content of the C12A7-based mineral phase in such a suitable C12A7-based calcium aluminate material can be measured by, for example, the following X-ray diffraction / Rietveld method.

The C12A7-based mineral phase measured by X-ray diffraction preferably has a crystallite diameter of 150 to 500 nm, and more preferably 150 to 300 nm.
When the crystallite diameter of the C12A7-based mineral phase is within such a range, more excellent early strength development and pot life can be secured, and good fluidity and the like can be obtained.
The crystallite diameter is a value measured by powder X-ray diffraction, and is a value measured using an X-ray diffraction / Rietveld method (apparatus: X'Pert MPD manufactured by PANalytical Co., Ltd., analysis software: HighScorePlus). ..
Tube voltage: 45kV Tube current: 40mA

Further, the C12A7-based mineral has a lattice constant of the C12A7-based mineral phase measured by X-ray diffraction, preferably 11.940 to 11.975 Å.
By setting the lattice constant in such a range, it is possible to secure the pot life more effectively and to have more excellent quick-hardening property.
The lattice constant is a value measured by powder X-ray diffraction, and is a value measured using an X-ray diffraction / Rietveld method (device: X'Pert MPD manufactured by PANalytical Co., Ltd., analysis software: HighScorePlus). ..
Tube voltage: 45kV Tube current: 40mA

Further, as a suitable C12A7-based calcium aluminate material, the contained C2S is 25% by mass or less, preferably 20% by mass or less, and it is desirable that it is substantially not contained, and C3A is 5% by mass or less. Yes, it is desirable that it is not substantially contained, and CA is 10% by mass or less, preferably 5% by mass or less, and it is desirable that it is not substantially contained, and C2AS is 20% by mass or less, preferably 10% by mass. % Or less, and it is desirable that it is not substantially contained.
If each of the above minerals, C2S, C3A, CA, and C2AS, is contained in excess of each of the above ranges, the content of the C12A7-based mineral contained in the suitable C12A7-based calcium aluminate material will be reduced. , Early strength development may not be exhibited more firmly and effectively.
Here, "substantially free" means that these mineral phases are not prevented from being produced by using a raw material rich in Si, Ca or Al, which are impurities contained in the raw material. It is not intended to be actively produced and contained.

Further, as a main component according C12A7 based mineral phase, C2S, C3A, CA, preferred content of C2AS is constant less C12A7 based calcium aluminate material, it is more desirable substantially free of C4A3 S.
Substantially not contained means that, similarly to the above, it does not prevent the case where it is produced by SO ₃ which is an impurity contained in the raw material, and it is not positively produced and contained.
In the present specification, S means SO ₃ and S means SiO ₂ .

Further, it is desirable that Fe ₂ O ₃ is not substantially contained in the suitable C12A7-based calcium aluminate material. For example, the Fe content is preferably 5% by mass or less in terms of Fe ₂ O ₃ oxide. Is 1.5% by mass or less, and the contained C4AF is 0.5% by mass or less. Substantially, C4AF is hardly generated and is not included.

Further, a suitable C12A7-based calcium aluminate material has a total content of MgO, CaO, and mineral phases other than the above C2S, C3A, CA, and C2AS (remaining mineral phase) of 15% by mass or less, preferably 12. It is desirable that it is mass% or less.
If it exceeds 15% by mass, the content of the C12A7-based mineral contained is reduced, which is not preferable.

More preferably, the suitable calcium aluminate material used in the present invention can more effectively exhibit the effects of the present invention by satisfying the following formula.
L * ≧ −3.4 × Fe ₂ O ₃ +55
In the formula, L * indicates the color difference value (L * value) obtained by the CIE color difference formula of the calcium aluminate material, and for example, using a color difference meter (CR-300) manufactured by Konica Minolta Japan Co., Ltd., It is a value of brightness (L * value) specified by CIE (International Commission on Illumination), and Fe ₂ O ₃ is an oxide-converted amount of Fe contained.
If the degree of reduction at the time of firing when preparing the calcium aluminate material is too high, the L * value decreases, the activity of the C12A7 system decreases, the initial strength becomes insufficient, and the Fe ₂ O ₃ content increases. If a large amount exceeds the above-mentioned content range, the L * value decreases, but if it is within the above-mentioned Fe ₂ O ₃ content range, it does not matter.
The above formula shows the range for the elements whose L * value decreases due to the Fe ₂ O ₃ content, and the elements whose L * value decreases due to reduction firing, so that the L * value satisfies the above formula. Try to adjust the oxygen concentration during firing.

Further, preferably, the calcium aluminate material has an L * value of 67 to 85 determined by the CIE color difference formula.
When the L * value is within the above range, the early strength development is more excellent. Further, if the contained Fe ₂ O ₃ content is larger than the above-mentioned content range, the L * value decreases, but if it is the above-mentioned Fe ₂ O ₃ content range, it does not matter and L. * Values can be 67-85.

The calcium aluminate material used in the present invention includes calcium raw materials such as fresh lime, slaked lime, and limestone, aluminum hydroxide, alumina, aluminum raw materials such as bauxite and band spores, magnesium raw materials such as dolomite, and fluorite to be blended as necessary. Fluorine raw materials, etc. are mixed and crushed, or crushed and mixed, and this powder mixture is molded to obtain a molded product, which is fired and cooled using an electric furnace or a heating furnace, etc. Prepare the aluminate material.
It should be noted that those which are the raw materials of Fe contained in the suitable calcium aluminate material (for example, red iron oxide) are not positively blended. Fe contained in the obtained calcium aluminate material may be contained as an impurity in the above-mentioned compounding raw material, and may be contained as a result, but is not positively contained.

For example, as an example, the compounded raw material is powdered and mixed, and the molded product obtained by molding the mixed powder is sufficiently at a temperature of, for example, 1.25 to 1400 ° C., preferably 1300 to 1360 ° C., for example, 0.5 to 0.5 to 1. It can be produced by firing for 3 hours and then cooling at a cooling rate of 40 ° C./min or less, preferably 5-40 ° C./min. When preparing a suitable C12A7-based calcium aluminate material, the raw materials are blended so as to contain 70% or more of C12A7-based minerals.

For example, such firing when the raw material mixed powder is fired, and the molded product molded as necessary is fired and cooled at a cooling rate of, for example, 40 ° C./min or less, preferably 5 to 40 ° C./min. It is desirable that the L * value is 67 above so that the oxygen concentration in the medium is measured and the L * value of the obtained calcium aluminate material is measured so that L * ≧ −3.4 × Fe ₂ O ₃ +55 can be satisfied. It is desirable to adjust the oxygen concentration by introducing air or the like at the time of firing so as to be within the range of ~ 85.
That is, in order to secure good fluidity, secure pot life, and obtain quick hardness, firing at the firing temperature or the like, cooling at the cooling rate, and adjusting the oxygen concentration are suitable for the present invention. The calcium aluminate material to be used can be obtained.

The calcium aluminate material used in the present invention is pulverized to obtain a calcium aluminate material powder, and it is preferable to pulverize it to a brain specific surface area of 5000 to 7000 cm ² / g or more.
Further, if the specific surface area of the brain is too large, the fluidity is adversely affected, the pulverization time is required, the productivity is lowered, and the cost is high. Therefore, 5000 to 7000 cm ² / g is desirable.
Further, when pulverizing, a pulverizing aid (diethylene glycol, triethanolamine, etc.) may be added.

The calcium aluminate material of the present invention is water-treated. For example, by spraying water on the above-mentioned arbitrary C12A7-based calcium aluminate material powder and treating the surface of the calcium aluminate material with water. , A water-treated calcium aluminate material used in the present invention can be obtained.
By adding and blending water in a ratio of 0.25 to 2 parts by mass with respect to 100 parts by mass of the calcium aluminate material powder, the above-mentioned effect of the present invention can be exhibited.

By treating the calcium aluminate material with water, a hydrate layer is formed on at least a part of the surface of the calcium aluminate material. The generated hydrate layer, for example _{CaO · Al 2 O 3 · 10H} 2 O, 2CaO · Al 2 O 3 · 8H 2 O, 3CaO · Al 2 O 3 · 6H 2 O, 3CaO · Al 2 O 3 · 8H ₂ O, can be exemplified _{4CaO · Al 2 O 3 · 13H} 2 O, 4CaO · Al 2 O 3 · 19H 2 O, Al 2 O 3 · 3H 2 hydrate layer of O and the like.

The method for water-treating the calcium aluminate material powder is not particularly limited as long as the calcium aluminate material water can be sprayed uniformly, and for example, it can be sprayed using a commercially available spraying device or the like.
Mixing and stirring may be performed while spraying water, or mixing and stirring may be performed immediately after spraying, or any method may be used.

The fast-curing admixture for cement of the present invention contains boric acid. Boric acid is contained in an amount of 1.2 to 1.8 parts by mass, preferably 1.4 to 1.6 parts by mass, based on 100 parts by mass of the water-treated calcium aluminate material.
By being contained in such a mass ratio, early strength development and pot life can be ensured, and workability can be improved.
Further, it is desirable that boric acid is in the form of a powder having a brain specific surface area of 5000 to 7000 cm ² / g, similarly to the calcium aluminate material powder, and the above-mentioned effect of the present invention can be more effectively exerted. .. Further, boric acid is not limited to powder, and may be liquid.
Even with oxycarboxylic acid, the effects of the present invention cannot be obtained with citric acid, tartaric acid, succinic acid, and lactic acid other than boric acid.

Further, the quick-hardening admixture for cement of the present invention includes gypsum. Examples of gypsum (calcium sulfate) include anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, or a mixture thereof.
In such gypsum, the blending ratio of the gypsum to the water-treated calcium aluminate material is calcium aluminate material: gypsum (mass ratio) = 4: 6 to 6: 4, preferably 5: 4 to 6: 4. included.
By being contained in such a mass ratio, early strength development and pot life can be ensured, and workability can be improved. However, the gypsum content is an amount calculated as a total amount converted to CaSO ₄ (anhydrous gypsum).
Further, it is desirable that the gypsum has a specific surface area of 5,000 to 7,000 cm ² / g, which is the same as that of the calcium aluminate powder, so that the effect of the present invention can be more effectively exhibited. Is possible.

The quick-hardening admixture for cement of the present invention does not include slag, alkali metal carbonate, aluminum sulfate, alkali metal sulfate, and quicklime.

In the method for producing a quick-hardening admixture for cement of the present invention, the quick-hardening admixture for cement of the present invention can be prepared by mixing water-treated calcium aluminate powder with boric acid and gypsum. ..
Specifically, a step of preparing a water-treated calcium aluminate material powder by spraying and mixing 0.25 to 2 parts by mass of water with respect to 100 parts by mass of calcium aluminate powder, the water treatment. 1.2 to 1.8 parts by mass of boric acid in 100 parts by mass of the calcium aluminate material powder, and the mass ratio of the water-treated calcium aluminate material powder and gypsum is 4: 6 to 6: 4. It is a method including a step of adding gypsum to calcium and mixing it uniformly.

For example, the calcium aluminate material is pulverized to a brain specific surface area of 5000 to 7000 cm ² / g, for example, by a ball mill, and the calcium aluminate material powder is mixed by spraying water, and then boric acid powder and gypsum powder are mixed. Can be prepared by mixing.
Alternatively, the calcium aluminate powder and boric acid are pulverized together with, for example, a ball mill to a brain specific surface area of 5000 to 7000 cm ² / g, and water is sprayed and mixed with the mixed powder, and gypsum powder is added thereto. It is also possible to prepare by adding and blending.
Further, boric acid may be liquid as well as powder.
It should be noted that the effect of the present invention cannot be obtained even if water treatment is performed before the calcium aluminate material is pulverized.

The fast-hardening cement composition of the present invention can be obtained by mixing the quick-hardening admixture for cement of the present invention thus obtained with an arbitrary cement.
Any commercially available cement can be applied as the cement to which the quick-hardening admixture for cement of the present invention is blended, for example, early-strength Portland cement, ultra-early-strength Portland cement, ordinary Portland cement, and moderate. At least one selected from hot Portland cement, low heat Portland cement, sulfate resistant Portland cement, fly ash cement, blast furnace cement, silica cement and the like can be used.

The method for mixing the quick-hardening admixture for cement, cement, water, etc. of the present invention is not particularly limited, and the mixture may be mixed in a predetermined ratio and then mixed using a conventional mixing device.
In addition, if necessary, various retarders (gluconate, tartaric acid and salts thereof, etc.), coagulation regulators (lignin sulfonic acid type, oxycarboxylic acid type, saccharides, etc.) are used as long as they do not affect the effect of the present invention. Organic acids or alkali metal salts of organic acids and alkaline earth metal salts) and water reducing agents (alkylallyl sulfonic acid type, naphthalene sulfonic acid type, melamine sulfonic acid type, polycarboxylic acid type, AE water reducing agent, high performance water reducing agent, Liquid or powder admixtures such as high-performance AE water reducing agents, fine aggregates (river sand, sea sand, mountain sand, crushed sand and mixtures thereof), and coarse aggregates (river gravel, sea gravel, crushed stone). And a mixture thereof) and the like can be blended. It should be noted that preferably, slag, alkali metal carbonate, aluminum sulfate, alkali metal sulfate, fresh lime, malic acid, fumic acid, and citric acid are not contained.

Further, the method of mixing with water when preparing a cement paste, mortar, concrete or the like using the fast-curing cement composition of the present invention is not particularly limited, and after blending in a predetermined ratio, it is commonly used. It may be mixed using the mixing device of.

As described above, in the quick-hardening additive for cement of the present invention, the fast-hardening cement composition of the present invention obtained by adding to an arbitrary cement can secure a sufficient pot life, and is good for 3 hours. It has strength-developing property, and desired quick-hardening property can be obtained in the field, and it is possible to operate a design for obtaining good initial strength-developing property while ensuring workability extremely easily.

The present invention will be described based on the following Examples, Comparative Examples and Test Examples.
1) Preparation of quick-hardening admixture for cement CaCO ₃ , SiO ₂ , Al ₂ O ₃ , so that the target chemical composition of the C12A7-based calcium aluminate material (CA material) used for the quick-hardening admixture for cement is shown in Table 1. A C12A7-based calcium aluminate material powder was prepared by mixing and pulverizing each reagent of Fe ₂ O ₃ , MgO, TiO ₂ , and CaF ₂ .

Here, SiO ₂ , Fe ₂ O ₃ , and TiO ₂ are calcium oxide raw materials such as quicklime, slaked lime, and limestone, aluminum hydroxide, alumina, and bokisite when actually producing C12A7-based calcium aluminate material in an actual machine. When aluminum raw materials such as band spores, fluorine raw materials such as fluorite, and magnesium raw materials such as dolomite to be blended as necessary are used, SiO ₂ , Fe ₂ O ₃ , and TiO ₂ may be contained as impurities as a result. Therefore, it is used assuming such a case (it is not intended to be actively contained).

The C12A7-based calcium aluminate powder was pressure-molded, the molded product was fired in an electric furnace at 1340 ° C. for 30 minutes, and then cooled at each cooling rate shown in Table 2, and the C12A7-based C12A7 series shown in Table 2 was cooled. A calcium aluminate material (CA material) was obtained.

The obtained C12A7-based calcium aluminate material was analyzed according to JIS R 5204 using a fluorescent X-ray analyzer (manufactured by PANalytical Co., Ltd .; Axios), and contained SiO ₂ , Al ₂ O ₃ , and TIO. The content ratios of ₂ , Fe ₂ O ₃ , F component, etc. were measured.
The results of these chemical compositions are shown in Table 2.

Further, the obtained C12A7-based calcium aluminate material powder is contained in the C12A7-based and further C3A by using the X-ray diffraction / Rietveld method (device: X'Pert MPD manufactured by PANalytical Co., Ltd., analysis software: HighScorePlus). The mineral content and the lattice constant of the crystals of the C12A7 mineral phase were measured.
Tube voltage: 45kV Tube current: 40mA
The results are shown in Table 2.
Here, the lattice constant of the crystal of the C12A7-based mineral phase was measured using the crystal structure of C11A7CaF ₂ .

The crystallite diameter of the crystal of the C12A7-based mineral phase was measured by the X-ray diffraction / Rietveld method (apparatus: X'Pert MPD manufactured by PANalytical Co., Ltd., analysis software: HighScorePlus) using the C11A7CaF ₂ crystal structure.
Tube voltage: 45kV Tube current: 40mA
The results are also shown in Table 2.

Next, the C12A7-based calcium aluminate material was pulverized to adjust the brain specific surface area to 5000 to 7000 cm ² / g.

(Examples 1 to 5)
Water was sprayed on 2000 g of C12A7 calcium aluminate powder having a specific surface area of 5000 to 7000 cm and ² / g by spraying water at the mass ratio shown in Table 3, and immediately tumbler mixer (Seiwa Giken Co., Ltd.) , Model number TM-36S) for 1 hour to prepare a water-treated C12A7-based calcium aluminate powder.

Next, boric acid powder (reagent, manufactured by US Borax) and anhydrous gypsum powder having a brain specific surface area of 5000 to 7000 cm ² / g with respect to 100 parts by mass of the obtained water-treated C12A7-based calcium aluminate powder. (Brain specific surface area 6800 cm ² / g) was added at the blending ratio shown in Table 3 and mixed uniformly to prepare a quick-hardening admixture for each cement of Examples 1 to 5.

(Comparative Example 1)
The C12A7-based calcium aluminate powder that had not been treated with water and the anhydrous gypsum powder were added in the blending ratios shown in Table 3 and mixed uniformly to obtain a quick-hardening admixture of Comparative Example 1. A coagulant such as boric acid was not added to the fast-curing admixture of Comparative Example 1.

(Comparative Example 2)
The C12A7-based calcium aluminate powder that had not been treated with water and the anhydrous gypsum powder were added in the blending ratios shown in Table 3 and mixed uniformly to obtain a quick-hardening admixture of Comparative Example 1. A coagulant such as boric acid was not added to the fast-curing admixture of Comparative Example 2.

(Comparative Example 3)
By adding the C12A7 calcium aluminate powder, the boric acid powder, and the anhydrous gypsum powder that have not been treated with water in the blending ratios shown in Table 3 and mixing them uniformly, the quick-hardening property of Comparative Example 1 It was used as an admixture.

(Comparative Example 4)
In the same manner as in Comparative Example 3 except that citric acid powder (reagent, manufactured by Kishida Chemical Co., Ltd.) was used instead of the boric acid powder of Comparative Example 3, the addition was made uniformly in the blending ratio shown in Table 3. By mixing, the fast-curing admixture of Comparative Example 4 was obtained.

(Comparative Example 5)
In the same manner as in Comparative Example 3 except that malic acid powder (reagent, manufactured by Kanto Chemical Co., Inc.) was used instead of the boric acid powder of Comparative Example 3, it was added uniformly at the blending ratio shown in Table 3. By mixing, the fast-curing admixture of Comparative Example 5 was obtained.

(Comparative Example 6)
In the same manner as in Comparative Example 3 except that humic acid powder (reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of the boric acid powder of Comparative Example 3, the powder was added in the blending ratio shown in Table 3. By uniformly mixing, the fast-curing admixture of Comparative Example 5 was obtained.

(Comparative Example 7 to Comparative Example 10)
The boric acid added and blended using the water-treated C12A7-based calcium aluminate powder obtained by changing the amount of watering (spraying) with respect to the water-treated C12A7-based calcium aluminate powder at the ratio shown in Table 3. The fast-curing admixtures of Comparative Examples 7 to 10 were obtained in the same manner as in Example 1 except that the amount of the powder added was changed at the ratio shown in Table 3.

(Comparative Examples 11 to 13)
The fast-curing admixtures of Comparative Examples 11 to 13 were obtained in the same manner as in Example 2 except that citric acid powder, malic acid powder, and humic acid powder were used instead of boric acid powder in Example 2. It was.

2) Preparation of mortar The mass ratio of early-strength cement (HC: manufactured by Sumitomo Osaka Cement Co., Ltd.) and the fast-hardening admixture powders obtained in Examples 1 to 5 and Comparative Examples 1 to 13 was 1: 2. Mix at a ratio of 35 parts by mass of the following aqueous solution and 3 parts by mass of a dispersant (Mighty 150, manufactured by Kao Co., Ltd.) with respect to 100 parts by mass of the total amount of the early-strength cement and the quick-hardening admixture. Then, 0.05 parts by mass of an antifoaming agent (Adecanate B211F, manufactured by Adeca Co., Ltd.) was further mixed and uniformly mixed to prepare each mortar.

The aqueous solution is an aqueous solution in which tartaric acid (reagent, manufactured by Wako Pure Chemical Industries, Ltd.) and sodium gluconate (reagent, manufactured by Kishida Chemical Industries, Ltd.) are previously dissolved. The content ratio of these tartaric acid and sodium gluconate is added by 0.3 parts by mass with respect to 100 parts by mass of the total amount of the early-strength cement and the quick-hardening admixture.

3) Test Example (Test Example 1) Potability Time For each mortar obtained above, the potability time of each mortar was measured according to JIR R 5201 (physical test method for cement).
However, a conical needle having a diameter of 1 inch and a height of 2 inches was used as the closing needle, and the time when the penetration depth became 1.5 mm was defined as the pot life.
The results are shown in Table 3.

(Test Example 2) Early (3 hours) strength For each of the obtained mortars, the 3-hour strength (early strength) at 20 ° C. was measured according to the old JIS R 5201.
The results are shown in Table 3.

From the above test results, the mortar using the quick-hardening admixture for cement of the example has a physical property of a pot life of 50 minutes or more and a strength of 18 N / mm ² or more for 3 hours, and secures a sufficient working time. It can be seen that the workability is excellent, and the early strength development is also excellent.

On the other hand, in the case of Comparative Example 2, the pot life is slightly longer than that in Comparative Example 1, but the pot life is not sufficient, and the C12A7-based material not treated with water in Comparative Examples 3 to 6 is used. When is used, it is not possible to have a sufficient pot life even when various retarders are added and blended.

Further, also in the cases of Comparative Examples 7 and 8 in which the amount of water treated with respect to the C12A7 calcium aluminate material powder is outside the range of the present invention, it is not possible to have a sufficient pot life, and the amount of boric acid blended. However, in the cases of Comparative Examples 9 and 10 which are outside the scope of the present invention, it can be seen that the pot life cannot be sufficiently secured (Comparative Example 9) and the early strength development is inferior (Comparative Example 10). ..
It can be seen that those using citric acid, malic acid or humic acid instead of boric acid in Comparative Examples 11 to 13 do not have a sufficient pot life and are also inferior in early strength development.

By adding the quick-hardening admixture for cement of the present invention to any cement, sufficient visible time can be secured and early strength can be developed, and construction work and civil engineering work of tunnels and underground spaces can be realized. , Water stoppage work, spraying work on walls, etc., repair work on urgent roads, etc., and as a soil conditioner, while ensuring a predetermined handling time, the strength should be developed promptly after the pot life has elapsed. Can be usefully applied to the required work area.

Claims (4)

It contains a calcium aluminate material whose surface has been water-treated, boric acid, and gypsum, and the boric acid is 1.2 to 1.8 parts by mass with respect to 100 parts by mass of the water-treated calcium aluminate material. include, plaster, 4 at a mass ratio relative to the water treated calcium aluminate material: 6 to 6: included in a ratio of 4, characterized in Rukoto, cement rapid hardening admixture. In the quick-hardening admixture for cement according to claim 1, the calcium aluminate material whose surface has been water-treated is surface-treated with 0.25 to 2 parts by mass of water with respect to 100 parts by mass of the calcium aluminate powder. It is characterized by being done. Quick-hardening admixture for cement. A fast-hardening cement composition comprising the quick-hardening admixture for cement according to claim 1 or 2 and cement. A step of preparing a water-treated calcium aluminate powder by spraying 0.25 to 2 parts by mass of water with respect to 100 parts by mass of the calcium aluminate powder and mixing them to prepare the water-treated calcium aluminate powder. Add 1.2 to 1.8 parts by mass of boric acid to 100 parts by mass, and add gypsum powder so that the weight ratio of water-treated calcium aluminate powder and gypsum powder is 4: 6 to 6: 4. A method for producing a quick-hardening admixture for cement, which comprises a step of blending and uniformly mixing.