JP2021169385A - Cement quick-setting admixture and cement composition - Google Patents

Abstract

To provide a cement quick-setting admixture having excellent quick-setting and spraying properties.SOLUTION: The cement quick-setting admixture of the present invention includes a C3A-containing powder with 3CaO-Al2O3(C3A) and a C12A7-containing powder with 12CaO-7Al2O3(C12A7).SELECTED DRAWING: None

Description

The present invention relates to a cement quick-setting admixture and a cement composition.

So far, various developments have been made on cement quick-setting admixtures. As a technique of this kind, for example, the technique described in Patent Document 1 is known. Patent Document 1 _{describes a quick-setting admixture in a spray material containing C 12} A ₇ as calcium aluminate (CAb, CAe, etc. in Table 3).

International Publication No. 2005/019131

However, as a result of the examination by the present inventor, it has been found that the quick-setting agent described in Patent Document 1 has room for improvement in terms of quick-setting property and sprayability.

As the calcium aluminate component in the cement quick-setting admixture, 12CaO / 7Al ₂ O ₃ (C ₁₂ A ₇ ), which is excellent in quick-setting property in that the time to set is short, is often used alone.
However, according to the study of the present inventor, it has been found that when C ₁₂ A ₇ is used alone, the initial setting is relatively slow, so that rebound may occur when applied to a spray material, for example. ..
_{Further diligent research based on these findings revealed that by using a mixture containing a C 3} A-containing powder and a C ₁₂ A _7- containing powder in a cement quick-setting agent, quick-setting property when used in a cement composition. And, it has been found that the sprayability can be improved, and the present invention has been completed.

According to the present invention
_{C 3} A-containing powder containing ₃ CaO · Al ₂ O 3 (C ₃ A) and
Containing C ₁₂ A _7- containing powder containing 12 CaO · 7 Al ₂ O ₃ (C ₁₂ A _7),
Cement quick-setting agent is provided.

Further, according to the present invention.
A cement composition comprising the above cement quick-setting admixture and cement is provided.

According to the present invention, there is provided a cement quick-setting agent having excellent quick-setting property and spraying property when used in a cement composition, and a cement composition.

The cement quick-setting admixture of the present embodiment will be outlined.

Cement quick-setting admixture is, _C 12 _{A 7} containing powder comprising a _{C 3} A content powder containing _{3CaO · Al 2 O 3 (C} 3 A abbreviated), 12CaO _· 7Al ₂ O ₃ a _(C 12 _{A 7} hereinafter) And, including.

This cement quick-setting admixture is used in the quick-setting admixture used to form cement concrete. Here, cement concrete is a general term for cement paste, mortar, or concrete.

According to the findings of the present inventor, _{by using a mixture containing a C 3} A-containing powder and a C ₁₂ A _7- containing powder in a cement quick-setting agent, quick-setting and spraying when used in a cement composition. We have found that the properties can be improved, and have completed the present invention.

Although the detailed mechanism is not clear, C ₁₂ A ₇ is excellent in increasing the reaction rate, while C ₃ A _{has a faster reaction rate than C 12} A ₇ , so by using these together, it is possible to achieve condensation. It is considered that the time is shortened and the initial setting is relatively quick, so that the occurrence of rebound is suppressed, so that the balance between the quick setting and the spraying property can be achieved.

The present inventor prepared the following samples A to C, and measured the temperature rise over time by the following procedure using the samples A to C.
(Cement quick-setting agent)
・ Cement quick-setting agent A: C ₃ A high-content clinker crushed product ・ Cement quick-setting agent B: amorphous C ₁₂ A ₇ high-content clinker crushed product ・ Cement quick-setting agent C: mixed product of samples A and B (Sample A: Mixing ratio of sample B is 15:85 in terms of mass)
(procedure)
In an environment of room temperature of 20 ° C. and relative humidity of 90%, 20 g of cement quick-setting admixtures A to C and 100 g of water were mixed for 30 seconds to prepare 120 g of samples A to C (paste) in a plastic container. A spatula was used for mixing.
· Making an initial temperature of each sample A~C immediately after the T _0, when the temperature after X minutes later adjustment was T _X (X can be any integer from 1 to 30.), The temperature increase rate for, was calculated from the formula _{(T X -T 0) / T} 0. For temperature measurement, thermocouples were inserted into samples A to C, and the temperature change was measured every 1 minute.

Result of the temperature rise rate obtained by the above procedure, after a lapse of 5 minutes _{(T 5 -T 0) / T} 0 , the sample A was greater than the sample B. From this, _{it is inferred that C 3} A has a faster initial condensation than _{C 12} A _7. Further, in (T _5- T ₀ ) / T ₀ after 5 minutes, the sample C was about the same as or higher than the sample A. From this, it is inferred that the effect of initial coagulation can be obtained by using _{C 3} A and C ₁₂ A _{7 together.}
On the other hand, (T _30- T ₀ ) / T ₀ after 30 minutes showed a higher value in sample C than in both sample A and sample B. From this, it can be inferred that the combined use of _{C 3} A and C ₁₂ A _{7 provides an excellent effect of quick connection.}

_{In the cement quick-setting admixture of the present embodiment, using T 0} and T ₃₀ obtained in the above procedure, the lower limit of the temperature rise rate calculated from the formula (T ₃₀ −T ₀ ) / T _{0 is, for example, 2.} It is 6 or more, preferably 2.7 or more, and more preferably 2.9 or more. Thereby, the quick connection can be improved. The upper limit of the temperature rise rate is not particularly limited, but may be, for example, 5.0 or less, or 4.5 or less.

According to this embodiment, it is possible to realize a cement quick-setting agent having excellent quick-setting and spraying properties.

The cement coagulant is composed of a mixture containing _{C 3} A-containing powder and C ₁₂ A _7- containing powder, and a part of the content of _{C 12} A _{7 can be replaced with C 3} A within an appropriate range. be. By using two kinds of powders, the substitution ratio can be controlled relatively easily and stably as compared with the case of adjusting the composition ratio of the mineral composition in one clinker. Therefore, the quick-setting property and the spraying property of the cement quick-setting agent can be stably exhibited.

The cement quick-setting admixture of the present embodiment can be used for various purposes. For example, as a quick-setting admixture for spraying, a spraying material used for spraying concrete is used as a part of a component. May be good.

Hereinafter, the cement quick-setting admixture of the present embodiment will be described in detail.

The cement quick-setting admixture is a composition composed of a mixture of _{a C 3} A-containing powder and a C ₁₂ A _7- containing powder as a calcium aluminate-based powder. This composition may be solid at 20 ° C. or may be entirely powdered.
In the composition _{, at least one of the C 3} A-containing powder and the C ₁₂ A _7- containing powder may be used in combination of one or more species.

The C ₃ A-containing powder may be composed of a clinker pulverized product containing _{C 3 A.}

The C ₃ A-containing powder may contain, for example, C ₃ A as a main component. The main component, the content of _{C 3} A of _{C 3} A content in the powder is in mass conversion means 50 mass% or more, preferably 70% by mass, more preferably 95% by mass. The contained C ₃ A is composed of crystalline material.

The C ₃ A-containing powder may or may not contain an amorphous _{C 3 A approximate composition containing SiO 2} , B ₂ O ₃ , P ₂ O ₅ , and the like.
The _{amorphization rate of C 3 A in the C 3} A-containing powder is preferably 60% or less, more preferably 50% or less, further preferably 30% or less, and even more preferably 20% or less in terms of mass. As a result, the initial cohesiveness can be enhanced.

_{CaO / Al 2} O ₃ in the C ₃ A-containing powder has a molar ratio of, for example, 2.2 to 3.5, preferably 2.3 to 3.4. By setting this molar ratio within this range, excellent rapid connection can be obtained.

The C ₁₂ A ₇ containing powder may be composed of a clinker pulverized product containing _{C 12} A _7.

The C ₁₂ A _7- containing powder may contain, for example, C ₁₂ A ₇ as a main component. The principal component means that the _{content of C 12} A _{7 in the} powder containing C ₁₂ A ₇ is 50% by mass or more, preferably 70% by mass, and more preferably 90% by mass in terms of mass.

The C ₁₂ A _7- containing powder may contain the C ₁₂ A ₇ amorphous. Amorphous ratio of C ₁₂ A ₇ containing powder _C 12 _{A 7} in the in mass conversion, preferably at least 50%, more preferably 60% or more, more preferably 70% or more, even more 80% or more preferable. As a result, the initial cohesiveness can be enhanced.

CaO / Al ₂ O ₃ in the C ₁₂ A _7- containing powder has a molar ratio of, for example, 1.8 to 2.5, preferably 1.9 to 2.4. By setting this molar ratio within this range, the amorphization rate can be increased and excellent initial setting can be obtained.

As one of the corresponding cement quick-setting admixture, it is configured to include the _{C 3} A content powder comprises _{C 3} A as a main component, and a _C 12 _{A 7} containing powder containing _C 12 _{A 7} as a main component May be good.

The lower limit of the content of _{C 3} A in the cement quick-setting admixture is, for example, 1% by mass or more, preferably 5% by mass or more, more preferably 5% by mass or more in 100% by mass _{of the C 3} A-containing powder and the C ₁₂ A _{7-containing powder.} It is 10% by mass or more. Thereby, the sprayability can be improved. On the other hand, the upper limit of the content of _{C 3} A is, for example, 40% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less in 100% by mass _{of the C 3} A-containing powder and the C ₁₂ A _{7-containing powder.} Is. As a result, it is possible to suppress a decrease in quick connection.

The C ₃ A-containing powder and the C ₁₂ A _7- containing powder may contain components other than _{C 3} A and C ₁₂ A _{7 as long as} the effects of the invention are not impaired. As its components, for example, one of SiO ₂ , Fe ₂ O ₃ , MgO, TiO ₂ , ZrO ₂ , MnO, P ₂ O ₅ , Na ₂ O, K ₂ O, Li ₂ O, sulfur, fluorine, chlorine and the like. Or two or more can be mentioned. Other components, _{C 3} A content powder and _C 12 _{A 7-containing} powder, for example, 10 wt% or less, preferably 5 wt% or less, more preferably be at most 1 mass%.

Among these, the upper limit of the MgO content is, for example, 5% by mass or less, preferably 3% by mass or less, and more preferably 1% by mass or less in 100% by mass _{of the C 3} A-containing powder and the C ₁₂ A _{7-containing powder.} be. Thus, clinker containing C 3 _A, in and C ₁₂ synthesis process of clinker containing A _7, since it can be adopted relatively wide range the firing temperature, can be improved yield and production stability. The lower limit of the MgO content is not particularly limited and may be 0% by mass.

C ₃ at least one of the powders of the A-containing powder and _C 12 _{A 7} containing powder is not particularly limited, with the Blaine specific surface area, for ^{example, 2,000cm 2 / g~9,000cm 2 / g} , preferably from 3,000cm ² / g~8,000cm ² / g.
In the present specification, "~" means that an upper limit value and a lower limit value are included unless otherwise specified.

The average particle size of at least one of the C ₃ A-containing powder and the C ₁₂ A _7- containing powder is, for example, 1 μm to 50 μm, preferably 5 μm to 20 μm.
In the present specification, the average particle size can be determined by a laser diffraction / scattering type particle size distribution measuring device or the like.

The _{content of the C 3} A-containing powder and the C ₁₂ A _7- containing powder is, for example, 20% by mass to 70% by mass, preferably 30% by mass to 60% by mass, based on 100% by mass of the cement quick-setting admixture.

Cement quick-setting admixture as calcium aluminate powder, (compounds mainly the CaO component and _Al 2 _{O 3} component) _{C 3} A and _C 12 _{A 7} except other calcium aluminate, also contain a metal good.
Other calcium aluminates may be _{contained in the C 3} A-containing powder or the C ₁₂ A _7- containing powder, but may be contained as other powders other than these powders.
The other calcium aluminate may contain either crystalline or amorphous, and these may be used alone or in combination of two or more.

The content of each mineral composition in the cement quick-setting admixture and the calcium aluminate-based powder can be confirmed by a general analytical method. For example, the mineral composition of a crushed sample can be confirmed by powder X-ray diffraction and the data can be analyzed by the Rietveld method to quantify the mineral composition. It is also possible to calculate the amount of mineral composition based on the identification results of the chemical composition and powder X-ray diffraction.

The _{method for producing the C 3} A-containing powder or the C ₁₂ A _7- containing powder may include, for example, a step of firing a raw material mixture containing _{a CaO raw material and an Al 2} O _{3 raw material with a kiln.}

As the CaO raw material, those commercially available as an industrial raw material may be used, but for example, one or more selected from the group consisting of limestone, coal ash, quicklime, slaked lime, and acetylene-generated waste may be contained. Among these, slaked lime may be used.

As the Al ₂ O ₃ raw material, a commercially available raw material may be used, but for example, one or more selected from the group consisting of bauxite, aluminum hydroxide, and aluminum residual ash may be contained. The aluminum residual ash may be mainly composed of aluminum hydroxide.
Among these, bauxite may be used. As a result, the content of MgO contained in the calcium aluminate-based powder can be reduced.

After firing, these raw materials are mixed and pulverized so as to have a predetermined mineral composition ratio to obtain a raw material mixture.

The method of mixed pulverization is not particularly limited, and a dry pulverization method or a wet pulverization method can be applied. In the case of the wet pulverization method, it is necessary to perform a dehydration treatment for subsequent granulation. When quicklime is used as a raw material, it is desirable to use a dry method.
Also by adjusting the feed rate of the raw material can be controlled the CaO / Al ₂ O ₃ molar ratio of calcium aluminate powder.

The firing temperature may be, for example, 1,200 ° C to 1,600 ° C, or 1,300 ° C to 1,550 ° C. By setting it to the above lower limit value or more, the generation of impurities can be suppressed. By setting the value to the above upper limit or less, it is possible to prevent the compound from melting.
A kiln such as an electric furnace or a rotary kiln can be used for firing.

By firing, a baked mass (clinker) formed by firing the raw material components is obtained. The clinker may be crushed by a known method to obtain a crushed product.
From the above, C ₃ A-containing powder and C ₁₂ A _7- containing powder can be obtained.

The cement quick-setting admixture may contain one or more selected from the group consisting of calcium sulfate, alkali metal sulfate, alkali metal carbonate, and calcium hydroxide.

The cement quick-setting agent may contain calcium sulfate as an auxiliary agent for improving the strength development.
Examples of calcium sulfate include gypsum such as anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. As the calcium sulfate, naturally produced natural gypsum, excretion gypsum obtained as an industrial by-product, hydrofluoric acid by-product anhydrous gypsum, or the like may be used. One or more of these can be used. Above all, anhydrous gypsum may be used from the viewpoint of developing adhesive strength.

The content of calcium sulfate in the cement quick-setting admixture is, for example, 10 parts by mass to 100 parts by mass, preferably 20 parts by mass to 80 parts by mass with respect to 100 parts by mass _{of the C 3} A-containing powder and the C ₁₂ A _{7-containing powder.} It is a mass part.

The cement quick-setting agent may contain an alkali metal sulfate as an auxiliary agent for improving the strength development.
Examples of the alkali metal sulfate include sodium sulfate, potassium sulfate, lithium sulfate and the like. These may be used alone or in combination of two or more. Among these, neutral anhydrous bow glass may be used as the sodium sulfate.

The content of the alkali metal sulfate in the cement quick-setting admixture is, for example, 10 parts by mass to 100 parts by mass, preferably 20 parts by mass with respect to 100 parts by mass _{of the C 3} A-containing powder and the C ₁₂ A _{7-containing powder.} ~ 80 parts by mass.

The cement quick-setting agent may contain an alkali metal carbonate as an auxiliary agent to assist in promoting initial setting.
Examples of the alkali metal carbonate include sodium carbonate, potassium carbonate, sodium bicarbonate and the like, and one or more of these can be used.

The content of the alkali metal carbonate in the cement quick-setting admixture is, for example, 1 part by mass to 50 parts by mass, preferably 3 parts by mass with respect to 100 parts by mass _{of the C 3} A-containing powder and the C ₁₂ A _{7-containing powder.} ~ 20 parts by mass.

The cement quick-setting agent may contain calcium hydroxide as an auxiliary agent to assist in promoting initial setting.
Examples of calcium hydroxide include commercially available slaked lime and carbide slag produced as a by-product when acetylene is generated from calcium carbide. One or more of these can be used.

The cement rapid binder may include aluminum sulphate as an aid to increase the rate of condensation. The aluminum sulfate is not particularly limited, and commercially available ones can be used, and 0 to 18 hydroxides are preferable. In particular, when aluminum sulfate becomes an anhydrous salt, the dissolution rate becomes low, so that the effect of improving the setting property becomes small. Therefore, it is preferable to use a hydrous salt (a hydrous salt having a hydration number of 18 or less), and it is more preferable to contain an octahydrate salt in consideration of storage stability.

Alum is effective for promoting the disappearance of fluidity immediately after blending cement mortar or cement concrete, and for promoting the strength development for about one day. The alum is not particularly limited, and for example, any alum such as alum, chrome alum, iron alum, ammonium alum, sodium alum, and natural alum can be used or used in combination. In particular, it is preferable to include at least one selected from the group consisting of potassium alum, sodium alum, and ammonium alum as a material that loses the fluidity of cement mortar and cement concrete.

The content of calcium hydroxide in the cement quick-setting admixture is, for example, 1 part by mass to 50 parts by mass, preferably 3 parts by mass to 100 parts by mass with respect to 100 parts by mass _{of the C 3} A-containing powder and the C ₁₂ A _{7-containing powder.} It is 20 parts by mass.

Cement quick-setting agents include pH adjusters, dispersants, stabilizers, antifreeze agents, water-soluble accelerators, AE agents, water-reducing agents, AE water-reducing agents, coagulation retardants, thickeners, fibers, and fine powders. Additives may be included as long as the object of the present invention is not substantially impaired. These may be used alone or in combination of two or more.

The cement quick- _{setting admixture is obtained by mixing a C 3} A-containing powder and a C ₁₂ A _7- containing powder, and if necessary, the above-mentioned components.

The cement composition of the present embodiment contains the above-mentioned cement quick-setting admixture and cement.

The amount of the cement quick-setting admixture used varies depending on the purpose of use, but is usually 1 to 20 parts by mass, preferably 3 to 10 parts by mass, based on 100 parts by mass of cement.

Cement includes various types of Portorand cement such as ordinary, early-strength, ultra-fast-strength, low-heat, and moderate-heat, various mixed cements in which blast furnace slag, fly ash, or silica is mixed with these Portland cements, urban waste incineration ash, and sewage sludge. Waste-using cement produced from incineration ash, so-called eco-cement (R), filler cement mixed with limestone powder, etc., alumina cement, sulfolaminate cement, limestone-fired clay cement (LC3), etc. Can be mentioned. These may be used alone or in combination of two or more.

The amount of water used is not particularly limited, but usually, the water / cement composition ratio is, for example, about 25 to 70% by mass with respect to the cement composition composed of cement and a cement quick-setting admixture. , 30-60% by mass.

The kneading method is a generally used method and is not particularly limited. As the mixing device, any existing stirring device can be used, for example, a tilting mixer, an omni mixer, a V-type mixer, a Henschel mixer, a Nauter mixer and the like can be used.

For mixing, each material may be mixed at the time of construction, or a part or all of them may be mixed in advance.

The curing method of the cement composition is not particularly limited, and any of the commonly used curing methods such as normal temperature / normal pressure curing, steam curing, high temperature / high pressure steam curing, and pressure curing can be applied.

Cement compositions also include aggregates such as sand and gravel, fibrous materials, swelling materials, hardeners, coagulation adjusters, water reducing agents, high performance water reducing agents, AE agents, AE water reducing agents, high performance AE water reducing agents, Thickeners, rust inhibitors, antifreezes, heat hydration inhibitors, polymer emulsions, clay minerals such as bentonite and montmorillonite, ion exchangers such as zeolites, hydrotalcites, and hydrocarbimite, sulfates such as aluminum sulfate. Salts, phosphates, and one or more other admixtures such as boric acid can be used in combination as long as the object of the present invention is not substantially impaired.

As one embodiment of the cement composition, it can be used as a spraying material to be sprayed on an exposed ground surface, for example, in tunnels such as roads, railroads and headraces.

As the spraying method of the present embodiment, a dry spraying method can also be applied, but from the viewpoint of reducing the amount of dust, a wet spraying method in which water is added to the cement concrete side in advance and kneaded before using the cement quick-setting admixture is used. It is preferable to use it.

As a wet spraying method, cement, fine aggregate, coarse aggregate, and water are added and kneaded to form sprayed concrete, which is pneumatically fed, and a Y-shaped pipe is provided in the middle, and a quick-setting admixture supply device is provided from one of them. There is a method in which a cement quick-setting admixture is pneumatically fed and mixed to form a quick-setting wet sprayed concrete.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the description of these Examples.

<C ₃ A-containing powder 1>
The CaO raw material (limestone) and the Al ₂ O ₃ raw material (bauxite) were _{blended so as to have a CaO / Al 2} O ₃ molar ratio shown in Table 1, and mixed and pulverized to obtain a mixed raw material.
The powdery mixed raw material was placed in a platinum crucible, fired in an electric furnace at 1,350 ° C. for 30 minutes, taken out of the furnace, and a clinker was synthesized.
Using a ball mill, synthesized clinker with a Blaine specific surface area of 6,000 2 / ^g, an average particle size by grinding so as to 5μm in, a mineral ratio shown in Table 1 C _{3 A} content powder 1 (clinker (Powder) was prepared. In the C ₃ A-containing powder, _{the crystalline content of C 3} A was 90% by mass, and the content of MgO was 0% by mass.

<C ₃ A-containing powder 2>
First-class reagent CaCO ₃ and Al ₂ O ₃ were mixed at a ratio of CaO / Al ₂ O ₃ molar ratio of 3/1, and mixed and pulverized to obtain a mixed raw material.
The powdery mixed raw material was placed in a platinum crucible, fired in an electric furnace at 1,350 ° C. for 30 minutes, taken out of the furnace, and a clinker was synthesized.
Using a ball mill, synthesized clinker with a Blaine specific surface area of 6,000 2 / ^g, an average particle size by grinding so as to 5μm in, a mineral ratio shown in Table 1 C _{3 A} powder containing 2 (clinker (Powder) was prepared.

<C ₁₂ A _7- containing powder 1>
The CaO raw material (limestone) and the Al ₂ O ₃ raw material (bauxite) were _{blended so as to have a CaO / Al 2} O ₃ molar ratio shown in Table 1, and mixed and pulverized to obtain a mixed raw material.
The powdery mixed raw material was placed in a platinum crucible, fired in an electric furnace at 1,350 ° C. for 30 minutes, taken out of the furnace, and a clinker was synthesized.
Using a ball mill, the synthesized clinker is ^{pulverized so that the brain specific surface area is 6,000 cm 2} / g and the average particle size is 5 μm, and the C ₁₂ A _7- containing powder 1 (clinker) having the mineral ratio shown in Table 1 is obtained. (Powdered product) was prepared. C ₁₂ A _7-containing powder _is amorphous 93 wt% the content of the _C 12 _{A 7,} the content of MgO was mass 0%.

<C ₁₂ A _7- containing powder 2>
Reagent primary CaCO ₃ and Al ₂ O ₃ were mixed at a ratio of CaO / Al ₂ O ₃ molar ratio of 12/7, and mixed and pulverized to obtain a mixed raw material.
The powdery mixed raw material was placed in a platinum crucible, fired in an electric furnace at 1,350 ° C. for 30 minutes, taken out of the furnace, and a clinker was synthesized.
Using a ball mill, synthesized clinker with a Blaine specific surface area of 6,000 ² / g, was ground so as to 5μm in average particle size, the mineral ratio shown in Table 1 _C 12 _{A 7} containing powder 2 (clinker (Powdered product) was prepared.

In Table 1, the ratio (parts by mass) of the mineral composition in the quick-setting admixture composition was calculated based on the result of the chemical composition quantified by using fluorescent X-rays and the result of identification by powder X-ray diffraction.

<Preparation of cement quick-setting admixture>
The components shown in Table 2 were mixed at the blending ratios shown in Table 2 to prepare a cement quick-setting admixture.

In Tables 1 and 2, C ₃ A: _{3 CaO · Al 2} O 3 and C ₁₂ A ₇ : 12 CaO · _{7 Al 2} O ₃ are shown.
The ingredients in Table 2 are as follows.
・ Calcium sulfate: Natural gypsum ・ Sodium sulfate: Neutral anhydrous bow glass ・ Sodium carbonate: Na ₂ CO ₃ , commercial product ・ Calcium hydroxide: Slaked lime

The obtained cement quick-setting admixture was evaluated based on the following evaluation items.

<Preparation of cement composition>
The cement quick-setting admixture, cement, water, and sand of each Example / Comparative Example are mixed in a room at 20 ° C., and the blending amount of the quick-setting admixture in 100 parts by mass of the cement and the quick-setting admixture = 7 A mortar (cement composition) having a mass ratio of water / cement composition = 1/1 (mass ratio) and cement composition / sand compounding ratio = 1/3 (mass ratio) was prepared.
(Material used)
Cement: Ordinary Portland cement, commercial product Water: Tap water Sand: JIS standard sand

<Proctor penetration resistance value>
The Procter penetration resistance value (kN) was measured every minute from immediately after mixing the quick-setting agent to the cement composition mortar to 10 minutes in accordance with ASTM C 403 “Concrete setting time test method by penetration resistance”. The results are shown in Table 2.
When the proctor intrusive resistance value reaches 450 kN by 10 minutes ◎ When the proctor intrusive resistance value after 10 minutes is less than 450 kN and 150 kN or more ○ When the proctor intrusive resistance value after 10 minutes is less than 150 kN × Based on the criteria of, the quick-setting property of the cement quick-setting agent was evaluated.

<Spray evaluation>
The unit quantity of each material, cement 400 kg / ^{m 3,} fine aggregates 1,058kg / ^{m 3,} the spray concrete was prepared as coarse aggregate 711kg / ^{m 3,} and water 200 kg / ^{m 3,} Shintech concrete pumping machine " It was pumped at a speed of ^{10 m 3} / h by "MKW-25SMT". Compressed air is inserted from the Y-shaped pipe installed after the 3-inch pressure-resistant hose with a length of 10 m, the sprayed concrete is air-conveyed with a 2.5-inch material hose with a length of 10 m, and from the Y-shaped pipe installed at the end. Using the quick-setting agent adding device "NATM Cleat", the cement quenching agent obtained above is conveyed and mixed with the sprayed concrete so as to be 7 parts by mass with respect to 100 parts by mass of the cement in the sprayed concrete. This was made into quick-setting sprayed concrete, which was sprayed from a nozzle onto a flat sprayed surface. The distance between the nozzle and the spray surface was set to 2.0 cm.
At this time, the rebound (degree of rebound) of the quick-setting sprayed concrete from the sprayed surface was observed.
The sprayability of the cement quick-setting agent was evaluated as ◯ when there was no rebound of the quick-setting sprayed concrete or in the range where there was no practical problem, and x when the rebound occurred to the extent that the workability was reduced.

It was shown that the cement quick-setting agents of Examples 1 to 4 were superior in sprayability as compared with Comparative Example 1 and excellent in quick-setting property as compared with Comparative Example 2.

Claims (11)

_{C 3} A-containing powder containing ₃ CaO · Al ₂ O 3 (C ₃ A) and
Containing C ₁₂ A _7- containing powder containing 12 CaO · 7 Al ₂ O ₃ (C ₁₂ A _7),
Cement quick-setting agent. The cement quick-setting admixture according to claim 1.
The _{C 3} A content powder comprises the _{C 3} A as a main component, the _C 12 _{A 7} containing powder comprises a _C 12 _{A 7} as a main component, a cement quick-setting admixture. The cement quick-setting admixture according to claim 1 or 2.
The content of the _{C 3} A of _{C 3} A content powder and the _C 12 _{A 7-containing} powder is 40% by mass or less than 1 wt%, a cement quick-setting admixture. The cement quick-setting admixture according to any one of claims 1 to 3.
A cement quick-setting admixture in which the content of MgO in the C ₃ A-containing powder and the C ₁₂ A _{7-containing powder is 5% by mass or less.} The cement quick-setting admixture according to any one of claims 1 to 4.
A cement quick-setting admixture obtained by the following procedure and having a temperature rise rate of 2.6 or more and 5.0 or less.
(procedure)
In an environment of room temperature of 20 ° C. and relative humidity of 90%, 20 g of the cement quick-setting admixture and 100 g of water are mixed for 30 seconds to prepare a 120 g sample in a plastic container. When the initial temperature of the sample immediately after production is T ₀ and the temperature 30 minutes after production is T ₃₀ , the temperature rise rate is calculated from the _{formula (T 30} −T ₀ ) / T _0. The cement quick-setting admixture according to any one of claims 1 to 5.
Amorphous rate of the C _{3 A} is 60 mass% or less, cement quick-setting admixture. The cement quick-setting admixture according to any one of claims 1 to 6.
A cement quick-setting agent having an amorphization rate of C _{12 A 7 of 50% by mass or more.} The cement quick-setting admixture according to any one of claims 1 to 7.
A cement rapid binder comprising one or more selected from the group consisting of calcium sulfate, alkali metal sulfate, alkali metal carbonate, and calcium hydroxide. The cement quick-setting admixture according to any one of claims 1 to 8.
Powdered, cement quick-setting agent. The cement quick-setting admixture according to any one of claims 1 to 9,
Cement composition, including, with cement. The cement composition according to claim 10.
A cement composition used as a spraying material.