JP6989719B1 - Two-form quick-setting admixture, spraying material and spraying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-dose type quick-setting agent having the same or higher quick-setting property and handleability as conventional ones and capable of reducing the environmental load. SOLUTION: This is a two-dose type quick-setting admixture consisting of a combination of a liquid quick-setting admixture containing aluminum sulfate as a main component and a powder auxiliary agent containing calcium aluminate as a main component. [Selection diagram] None

Description

The present invention relates to a two-agent type quick-setting agent, a spraying material and a spraying method, and particularly to a two-agent type quick-setting agent, a spraying material and a spraying method used in the civil engineering / building field.

Conventionally, in order to prevent the collapse of exposed ground such as tunnel excavation, spraying is performed by a spraying method using a quick-setting spray concrete in which a quick-setting agent is mixed with concrete (see Patent Document 1). ..

In this spraying method, sprayed concrete is usually prepared at a cement, aggregate, and water metering and mixing plant installed at the excavation site, transported by an agitator truck, pumped by a concrete pump, and installed in the middle. This is a construction method in which a confluence pipe is mixed with a quick-setting agent pumped from the other side and sprayed as quick-setting spray concrete onto the ground surface until it reaches a predetermined thickness.

The quick-setting admixtures used in the spraying method can be broadly classified into powder quick-setting admixtures containing calcium aluminate, alkali metal aluminate, etc. as the main components, and alkali metal aluminate, aluminum sulfate, etc. as the main components. There are two types of liquid quick-setting agents.

The method of adding the powder quick-setting admixture is usually carried out in the range of 5 to 12% as the addition amount for powder mixing by air transportation.
In addition, as a characteristic of the powder quick-setting admixture, it has a large effect of promoting condensation when mixed with sprayed cement concrete, and since the concrete hardens quickly, it can protect the ground surface where there is a risk of collapse, and it also springs up. It can be mentioned that it has a great effect on spraying on water.
However, the quick-setting agent supply device for the powder quick-setting admixture is large-scale, and a separate device such as a compressor that prepares and pumps compressed air is required, and further, the powder quick-setting admixture is pneumatically fed. When mixed with sprayed cement concrete, there is a problem that a part of the powder quick-setting admixture may be scattered as dust in the work space.
Therefore, there has been a demand for a construction method that has sufficient rapid binding force with low addition and has a smaller amount of dust and rebound.
In addition, the initial strength of the quick-setting spray concrete using the powder quick-setting agent is improved by the powder quick-setting agent, but the long-term strength is 20 to 40% compared to the base concrete to which the powder quick-setting agent is not added. It tended to decline.

The characteristics of the liquid quick-setting admixture are that the quick-setting admixture supply device is simple, the supply to the sprayed cement concrete is quantitative, and the mixture with the sprayed cement concrete is good. Adhesion of cement sprayed concrete to the ground is good, and the rebound rate (rebound rate) is low.
However, the condensation promoting action when mixed with sprayed cement concrete is weaker than that of powder quick-setting agent, and it cannot be used for spraying on soft ground or spring water, and it is not suitable for thick spraying. There was a challenge.

As a construction method with a small amount of dust generated, a method has been proposed in which a quick-setting admixture is slurried with water or a liquid quick-setting admixture and added to and mixed with cement concrete. (See Patent Document 2 and Patent Document 3).
In particular, Patent Document 3 describes the use of a high-performance water reducing agent and the use of silica fume, but does not describe the use of both in combination.

However, this method is disadvantageous because it increases the water / cement ratio in terms of reducing the decrease in strength of the sprayed concrete.

In recent years, there has been a demand for higher quality quick-setting sprayed concrete. As one of the means, a quick-setting construction method for improving workability has been proposed by making a quick-setting agent into a slurry and blending alums with cement concrete (see Patent Document 4).
However, in recent years, there has been a demand for a lower cost spraying method by further improving workability, shortening the construction period, improving quick-setting and strength development, and further reducing rebound. ..

In addition, a blower containing a slurry-like quick-setting admixture, which is a mixture of a powder admixture containing alkaline earth metal carbonate, calcium aluminate, alkali metal sulfate, and calcium sulfate, and a liquid quick-setting admixture. A mounting material and a spraying method using the same have been proposed (see Patent Document 5).
However, Patent Document 5 describes that cement concrete containing fly ash and / or silica film and a high-performance water reducing agent is used in combination with a quick-setting agent slurry in which a powder quick-setting agent and a liquid quick-setting agent are mixed. There is no.

In addition, for the purpose of improving the pumping property and strength development of cement and hard-hardening cement concrete containing hard-hardening substances such as calcium aluminate, hard-hardening cement concrete using inorganic powder such as silica fume and fly ash is available. It has been proposed and disclosed to be used in combination with a high-performance water reducing agent (see Patent Document 6).
However, also in Patent Document 6, there is no description about using a quick-setting agent slurry in which a powder quick-setting agent and a liquid quick-setting agent are mixed in combination.

Special Publication No. 60-004149 Japanese Unexamined Patent Publication No. 2007-031166 Japanese Unexamined Patent Publication No. 10-317671 Japanese Unexamined Patent Publication No. 05-097941 International Publication No. 08/056716 Japanese Patent Application Laid-Open No. 2002-338316

Further, in addition to workability, environmental load reducing property has been attracting attention in recent years, and it is preferable that the quick-setting admixture and spraying material also have good environmental load reducing property.

From the above, it is an object of the present invention to provide a two-dose type quick-binding agent which has the same or better quick-setting property and handleability as the conventional one and can reduce the environmental load.

As a result of various studies to solve the above problems, the present inventors have found that the following problems can be solved by the present invention, and have completed the present invention. That is, the present invention is as follows.

[1] A two-dose type quick-setting admixture consisting of a combination of a liquid quick-setting admixture containing aluminum sulfate as a main component and a powder auxiliary agent containing calcium aluminate as a main component.
[2] The two-dose type quick-setting agent according to [1], wherein the pH of the liquid quick-setting agent is 7 or less.
[3] The two-dose type quick-setting admixture according to [1] or [2], wherein the content _{of R 2 O (R is an alkali metal) in the powder auxiliary agent is less than 1% by mass.}
[4] The two-drug type quick-setting agent according to any one of [1] to [3], wherein the powder auxiliary agent contains calcium sulfate and the content of the calcium sulfate is 10 to 50% by mass.
[5] The two-dose type quick-setting admixture according to any one of [1] to [4], wherein the powder auxiliary agent contains aluminum sulfate and the content of the aluminum sulfate is 20% by mass or less.
[6] A spraying material containing the two-component quick-setting admixture according to any one of [1] to [5] and cement concrete.
[7] Aluminum sulfate is 0.5 parts by mass or more, calcium aluminate is 0.5 parts by mass or more, and the total of aluminum sulfate and calcium aluminate is 0.5 parts by mass or more with respect to 100 parts by mass of cement in the cement concrete. The spraying material according to [6], which is 15 parts by mass or less with respect to 100 parts by mass of cement in the cement concrete.
[8] The mass ratio (Y / X) of the aluminum sulfate content (X) to the calcium aluminate content (Y) is 0.5 to 5, according to [6] or [7]. Spraying material.
[9] A spraying method in which a liquid quick-setting admixture containing aluminum sulfate as a main component, a powder auxiliary agent containing calcium aluminate as a main component, and cement concrete are mixed and sprayed.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a two-dose type quick-binding agent which has the same or higher quick-setting property and handleability as the conventional one and can reduce the environmental load.

Hereinafter, embodiments of the present invention (the present embodiment) will be described in detail. The parts and% used in this specification are based on mass unless otherwise specified. Further, cement concrete is a general term for cement paste, mortar, and concrete.

[1] Two-dose type quick-setting agent The two-agent type quick-setting agent according to the present embodiment includes a liquid quick-setting agent containing aluminum sulfate as a main component and a powder auxiliary agent containing calcium aluminate as a main component. Consists of a combination of. That is, the liquid quick-setting admixture and the powder auxiliary agent are physically separated until they are mixed and used.

(Liquid quick-setting agent)
The liquid quick-setting admixture according to this embodiment contains aluminum sulfate as a main component. By containing aluminum sulfate as a main component, the liquid quick-setting agent is less likely to become alkaline, and as a result, it is possible to improve handleability and environmental load reduction while maintaining good quick-setting.
Here, "containing aluminum sulfate as a main component" means that the content of aluminum sulfate (based on mass) is the highest among the quick-setting agent components of the liquid quick-setting agent, and 50% by mass in the quick-setting agent component. The above is preferable, 80% by mass or more is more preferable, 90% by mass or more is further preferable, and aluminum sulfate is the only component of the quick-setting admixture.

The pH of the liquid quick-setting admixture is preferably 7 or less, more preferably 5 or less. When the pH is 7 or less, the effect of reducing the environmental load can be exhibited. The pH is preferably 2 or higher.

In the liquid quick-setting admixture, aluminum sulfate is preferably contained in an amount of 20 to 40% by mass, more preferably 25 to 30% by mass. In particular, by containing 25 to 30% by mass of aluminum sulfate, it is possible to improve handleability and environmental load reduction while maintaining good quick connection. Water can be used as the liquid component that dissolves or disperses aluminum sulfate.

(Powder aid)
The powder auxiliary agent according to this embodiment contains calcium aluminate as a main component.
By containing calcium aluminate as a main component, good quick-setting and strength development can be enhanced.
Here, "containing calcium aluminate as a main component" means that the content of calcium aluminate (based on mass) is the highest among the quick-setting agent components in the powder auxiliary agent.

Here, calcium aluminate is _{a general term for compounds having CaO and Al 2} O ₃ as main components and having hydration activity _{, and Ca O and / or a part of Al 2} O ₃ is an alkali metal oxide or an alkali. Compounds replaced with earth metal oxides, silicon oxide, titanium oxide, iron oxide, alkali metal halides, alkaline earth metal halides, alkali metal sulfates, alkaline earth metal sulfates, etc., or CaO and Al ₂ A substance in which a small amount of these are solid-dissolved in a substance containing O _{3 as a main component, and the calcium aluminate may be either crystalline or amorphous.}

As a specific example of the crystalline substance, when CaO is C, Al ₂ O ₃ is A, and R ₂ O (for example, Na ₂ O, K ₂ O, Li ₂ O) is R, C ₃ A or an alkali metal thereof. Examples _{include C 14} RA ₅ , CA, C ₁₂ A ₇ , C ₁₁ A ₇ , CaF ₂ , C ₄ A, Fe ₂ O ₃ , and C ₃ A ₃ , CaSO _4, etc. Amorphous calcium aluminate is preferable because it is good.

The calcium aluminate used in the present embodiment is mixed with a trace amount of alkali metal and / or alkaline earth metal from an industrial raw material, and a part of calcium aluminate containing the alkali metal and / or alkaline earth metal is produced. It is possible, but not limited by the presence of these slight alkali metals and / or alkaline earth metals.

The CaO / Al ₂ O ₃ molar ratio of calcium aluminate is not particularly limited, but the molar ratio is preferably 2.0 to 3.0 in consideration of the strength development in the very early stage, and 2.2 to 2.8. Is more preferable. When the molar ratio is 2.0 or more, the coagulation property in the very early stage can be improved, and when it is 3.0 or less, good long-term strength development can be easily obtained.

The content of calcium aluminate in the powder auxiliary agent of the present embodiment is 30% by mass or more, preferably 30 to 80% by mass, and more preferably 45 to 60% in the powder auxiliary agent. preferable. When it is 30% by mass or more, good coagulation properties can be easily obtained. When it is 80% by mass or less, good long-term strength development can be easily obtained.

Blaine specific surface area of the calcium aluminate (hereinafter referred to simply as "Brain") is preferably 4000~8000cm ² / g, more preferably 5000~7000cm ² / g. When it is 4000 to 8000 cm ² / g, the initial strength development can be easily obtained, and the handleability of the mortar and / or concrete at the time of spraying can be improved.
The brain specific surface area is measured based on the specific surface area test described in JIS R 5201 “Physical test method for cement”.

_{The content of R 2} O (R is an alkali metal, preferably K ₂ O and Na ₂ O) in the powder auxiliary agent is preferably less than 1% by mass, and the content of _{R 2 O is 1% by mass.} When it is less than, the handleability and the environmental load reduction property can be improved. The content of R _{2 O} in the powder additive can be determined by atomic absorption spectrometry.

The powder auxiliary agent preferably contains calcium sulfate, and the content thereof is preferably 10 to 50% by mass, more preferably 20 to 40% by mass. When the content of calcium sulfate in the powder auxiliary agent is 10 to 50% by mass, the strength development can be improved.

Further, the powder auxiliary agent may contain aluminum sulfate, and its content (in terms of anhydrous salt) is preferably 20% by mass or less, and more preferably 15% by mass or less. When the content of aluminum sulfate in the powder auxiliary agent is 20% by mass or less, the setting property can be improved. Aluminum sulfate is preferably 0.3% by mass or more.

In the present specification, aluminum sulfate imparts an effect of mainly increasing the setting rate to cement mortar and cement concrete.

The aluminum sulfate is not particularly limited, and commercially available ones can be used, and the aluminum sulfate is preferably 0 to 18 hydroxide.

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 include an octahydrate salt in consideration of storage stability.

In the powder auxiliary agent, the mass ratio of aluminum sulfate (anhydrous salt equivalent) to calcium aluminate (aluminum sulfate / calcium aluminate) shall be 0.01 to 0.50 from the viewpoint of further improving the setting property. Is preferable, and 0.02 to 0.30 is more preferable.

The liquid quick-setting admixture and powder auxiliary agent according to the present embodiment can contain various additives in addition to the above-mentioned components as long as the effects of the present invention are not impaired, but from the viewpoint of handleability, they can be contained. It is preferable not to contain sodium aluminate.

[2] Spraying Material and Spraying Method The spraying material according to the present embodiment includes the two-part quick-setting agent of the present invention and cement concrete.
The cement used for the spraying material includes various Portland cements such as ordinary, early-strength, ultra-fast-strength, low-heat, and moderate heat, and various mixed cements in which these Portland cements are mixed with blast furnace slag, fly ash, or silica. Examples include filler cement mixed with limestone powder and blast furnace slow-cooled slag fine powder, and environment-friendly cement (eco-cement) manufactured from city waste incineration ash and sewage sludge incineration ash as raw materials.

Although an aggregate is actually used as the spraying material, the aggregate is not particularly limited, and a material having a low water absorption rate and a high aggregate strength is preferable. The maximum size of the aggregate is not particularly limited as long as it can be sprayed. As the fine aggregate, river sand, mountain sand, sea sand, lime sand, silica sand and the like can be used, and as the coarse aggregate, river gravel, mountain gravel, lime gravel and the like can be used. Crushed stone can also be used.

In the spray material according to the present embodiment, aluminum sulfate is 0.5 parts by mass or more, calcium aluminate is 0.5 parts by mass or more, and aluminum sulfate and calcium aluminum are 100 parts by mass or more with respect to 100 parts by mass of cement in cement concrete. The total amount of nate is preferably 15 parts by mass or less with respect to 100 parts by mass of cement in cement concrete.

The mass ratio (Y / X) of the aluminum sulfate content (X) and the calcium aluminate content (Y) to 100 parts by mass of cement is preferably 0.5 to 5. It is more preferably 0.8 to 3.0. When the mass ratio is 0.5 to 5, it is possible to prevent rebounding at the time of spraying and further improve the handleability.

The spraying method according to the present embodiment is a spraying method using the spraying material of the present invention, and is a liquid quick-setting admixture containing aluminum sulfate as a main component and a powder aid containing calcium aluminate as a main component. This is a method in which an agent and cement concrete are mixed and sprayed.

In the present invention, the powder quick-setting admixture and the liquid quick-setting admixture are merged and mixed in a mixing pipe immediately before being added to the sprayed cement concrete to form a slurry, thereby improving the mixing property with the sprayed cement concrete. It is preferable from the aspect. The water / cement ratio is preferably 65% or less.

Hereinafter, the contents will be described in more detail with reference to experimental examples, but the present invention is not limited thereto.

"Experimental Examples 1-1-1-14"
A commercially available aqueous solution of aluminum sulfate (concentration 27%) was used as the liquid quick-setting agent.
Further, calcium aluminate, calcium sulfate, and aluminum sulfate were mixed in the formulations shown in Table 1 to prepare a powder auxiliary agent.
Further, 800 g of cement, 2000 g of fine aggregate, and 400 g of water were mixed to prepare a mortar.
A liquid quick-setting admixture and a powder auxiliary agent were mixed with 100 parts by mass of the cement of this mortar in the formulations shown in Table 1 to prepare a spraying material. A coagulation test was conducted to measure the start time at which condensation starts from the time the spray material is prepared and the end time at which condensation ends. In addition, the compressive strength was measured. The results are shown in Table 1. Further, R _{2 O} ratio of pH and in the powder liquid auxiliaries quick-setting admixture are also shown in Table 1.
The pH was measured using a pH meter. R 2 _O ratio was measured by atomic absorption spectrometry.

Further, the unit cement amount is 400 kg / m ³ , the fine aggregate ratio (s / a) is 65%, and the unit water amount is 50 parts for 100 parts of cement. It was pumped using a pump "Shintech MKW-25MT". A Y-shaped mixing pipe is provided in the middle of the pressure-feeding pipe, and a liquid quick-setting admixture and a powder aid are pressure-fed to the concrete to make quick-setting sprayed cement concrete, and dust generated by spraying on the wall surface of the simulated tunnel. And the bounce was measured.

The materials used and various test methods are as follows.
"Material used"
Cement: Commercial product, ordinary Portland cement, density 3.15 g / cm ³
Fine aggregate: Himekawa River basin, Niigata Prefecture, density 2.61 g / cm ³
Coarse aggregate: Itoigawa No. 6, Niigata Prefecture Crushed stone, maximum size 15 mm, density 2.64
Water: Industrial water Calcium aluminate: CaO / Al ₂ O _{3 raw materials (CaCO 3} and Al ₂ O ₃ ) are crushed and mixed so as to have a molar ratio of 2.5, melted in an electric furnace, quenched, and vitrified. Rate 90%, Brain 5500cm ² / g
Aluminum sulfate: Commercial product, 8-hydrate, particle content of particles with a particle size of 10 μm or less: 5%
Calcium sulfate: Commercial product, anhydrous, brain value 4,000 ^{cm 2} / g, density 2.9 g / cm ³

"Test method"
Condensation test: Immediately after preparing the spray material, quickly mold it into a mold dedicated to the Proctor test, and measure the start time and end time of condensation from the time the spray material is prepared (measured according to JSCE-D102 Annex 3). did.

Compressive strength: Similar to the setting test, the compressive strength (N / mm ² ) from the time when the quick-setting mortar was prepared was measured. The age of the material was 3 hours, 1 day, and 28 days (measured according to JSCE D102).

Dust volume: Rapidly sprayed concrete was sprayed onto the simulated tunnel at a pumping rate of 10 ^{m 3 / h for 10 minutes.} The amount of dust was measured with a dust meter (Shibata Chemical Co., Ltd., measuring range 0.01 to 100 mg / m ³ , P-5L type) at a fixed position 5 m from the spraying place.

Bounce (rebound rate): Rapidly sprayed concrete was sprayed on a simulated tunnel with a height of 4.4 m and a width of 5.5 m, which was arched from an iron plate for 10 minutes at a pumping speed of 10 ^{m 3 / h.} After that, (rebound rate) = (amount of quick-setting sprayed concrete that fell without adhering to the simulated tunnel) / (amount of quick-setting sprayed concrete sprayed on the simulated tunnel) x 100 (%) did.

"Reference example"
Reference As the liquid quick-setting agent, an inorganic salt-based liquid quick-setting agent was used. As a reference powder auxiliary agent, a mineral-based powder quick-setting agent was used. The same test as the experimental example using these was performed. The results are shown in Table 1.
Inorganic salt-based liquid quick-setting agent: Product name "Natomic L" (aluminate alkaline solution system)
Mineral-based powder quick-setting agent: Product name "Natomic Z" (calcium aluminate mineral-based)

「実験例２−１〜２−６」
硫酸アルミニウムと水を表２に示す配合で混合して液体急結剤を調製した。
また、カルシウムアルミネート、硫酸カルシウム、及び硫酸アルミニウムを表２に示す配合で混合して粉体助剤を調製した。
実験例１に示したモルタルとコンクリートを用いた試験と同様に、凝結が開始される始発時間、凝結が終了する終結時間、圧縮強度、粉じん、跳ね返りを測定した。

"Experimental Examples 2-1 to 2-6"
Aluminum sulfate and water were mixed in the formulations shown in Table 2 to prepare a liquid quick-setting admixture.
Further, calcium aluminate, calcium sulfate, and aluminum sulfate were mixed in the formulations shown in Table 2 to prepare a powder auxiliary agent.
Similar to the test using mortar and concrete shown in Experimental Example 1, the starting time at which condensation started, the ending time at which condensation ended, compressive strength, dust, and rebound were measured.

INDUSTRIAL APPLICABILITY The present invention can be suitably used especially for quick-setting materials used in the fields of civil engineering, construction and the like.

Claims (3)

It is a two-part type quick-setting admixture consisting of a combination of a liquid quick-setting admixture containing aluminum sulfate as a main component and a powder auxiliary agent containing calcium aluminate as a main component.
_{The content of R 2} O (R is an alkali metal) in the powder auxiliary agent is less than 1% by mass, and the content is less than 1% by mass.
The powder auxiliary agent contains calcium sulfate, and the content of calcium sulfate in the powder auxiliary agent is 10 to 40 % by mass.
A two-dose type quick-setting admixture agent in which the powder auxiliary agent contains 8 to 18 hydroxides of aluminum sulfate, and the content of aluminum sulfate in the powder auxiliary agent is 0.3% by mass or more and 20% by mass or less. The two-dose type quick-setting agent according to claim 1, wherein the pH of the liquid quick-setting agent is 7 or less. A liquid quick-setting admixture containing aluminum sulfate as the main component,
A powder additive containing calcium aluminate as a main component, R _{2 O} in the powder aid (R is an alkali metal) and content of less than 1% by weight of the powder aid It contains calcium sulfate, the content of calcium sulfate in the powder auxiliary agent is 10 to 40 % by mass, the powder auxiliary agent contains 8 to 18 hydroxides of aluminum sulfate, and aluminum sulfate in the powder auxiliary agent. A spraying method in which a powder auxiliary agent having a content of 0.3% by mass or more and 20% by mass or less and cement concrete are mixed and sprayed.