JP2023149849A - Sprayable powder material and spray material - Google Patents

Abstract

To provide a sprayable powder material that ensures excellent condensation and strength even when combined with a fluorine-free liquid accelerator.SOLUTION: A sprayable powder material contains calcium aluminate, calcium aluminosilicate, calcium sulfate, cement, and aggregate with a maximum particle size of 1.2 mm or less. Preferably, the cement is high-early-strength cement.SELECTED DRAWING: None

Description

The present invention relates to a powder material for spraying and a spraying material.

Small cross-section headrace tunnels with a diameter of 2 to 5 meters are often excavated using tunnel boring machines (TBM), and shotcrete is used to stabilize the rock after excavation. However, conventional spraying requires the use of large construction machines and the need to transport concrete from outside the mine, which poses the problem of limiting work space and concrete work time.

As a means to solve this problem, we have developed a spraying method (Patent Document 1) that uses a combination of batch-mixed mortar and a rapidly hardening material slurry containing calcium aluminate to shorten the working time and improve the working environment (Patent Document 1), as well as TBM. A spraying material containing cement, aggregate with a maximum particle size of 2.5 mm, a substance containing slaked lime, and an alkali metal aluminate (Patent Document 2) has been proposed as a spraying material with improved workability for small-section tunnels that can be excavated. has been done.

However, when using a rapidly hardening material slurry containing calcium aluminate, it was necessary to improve the rapid setting immediately after spraying. In addition, cement, aggregate with a maximum particle size of 2.5 mm, slaked lime-containing substances, and spraying materials containing alkali metal aluminates use alkali metal aluminates, so they are a preventive measure against chemical injuries to workers. It was necessary to give sufficient consideration. For this reason, workers must wear full protective gear when spraying, which poses a problem in that work efficiency is degraded. Furthermore, it was necessary to improve long-term strength development and durability.

Therefore, in Patent Document 3, 100 parts of mortar containing calcium aluminosilicate, calcium sulfate, early-strengthening cement, and aggregate with a maximum particle size of 1.2 mm or less, and an acidic liquid containing an alkali metal element and/or fluorine are used. It is a spraying material containing 1 to 5 parts of solid content of calcium aluminosilicate, 1 to 10 parts of calcium aluminosilicate, 1 to 10 parts of calcium sulfate, and 20 to 55 parts of early strength cement in 100 parts of mortar. and 40 to 70 parts of aggregate with a maximum particle size of 1.2 mm or less, and 20 to 70 parts of aggregate with a maximum particle size of 0.6 to 1.2 mm out of 100 parts of aggregate with a maximum particle size of 1.2 mm or less. , spraying material with 80 to 30 parts of aggregate less than 0.6 mm is highly safe for the human body, has good material pumpability, has excellent physical properties even at low temperatures, and has low rebound. Suggest attachment materials.

Japanese Patent Application Publication No. 3-122040 Japanese Patent Application Publication No. 9-227198 Patent No. 4855321

However, Patent Document 3 assumes that it is used in combination with an acidic liquid quick-setting agent containing fluorine, and in that case, when a liquid quick-setting agent containing fluorine is added to cement/concrete, fluorine may be leached from the hardened material. Recently, there has been a need to pay attention to suppressing the elution of fluorine from the perspective of environmental conservation at construction sites.

In view of the above, an object of the present invention is to provide a powder material for spraying that can obtain good setting properties and strength even when combined with a liquid quick setting agent that does not contain fluorine.

As a result of intensive studies in view of the above problems, the present inventors came up with the following invention and found that the problems could be solved. That is, the present invention is as follows.

[1] A powder material for spraying containing calcium aluminate, calcium aluminosilicate, calcium sulfate, cement, and aggregate with a maximum particle size of 1.2 mm or less.
[2] The powder material for spraying according to [1], wherein the cement is an early strength cement.
[3] A spraying material comprising the powder material for spraying according to [1] or [2] and a liquid quick-setting agent that does not contain fluorine.

According to the present invention, it is possible to provide a powder material for spraying that can obtain good setting properties and strength even when combined with a liquid quick setting agent that does not contain fluorine.

Hereinafter, one embodiment (this embodiment) of the present invention will be described in detail. Note that parts and percentages in this specification are expressed on a mass basis unless otherwise specified.

[Powder material for spraying]
The powder material for spraying according to this embodiment contains calcium aluminate, calcium aluminosilicate, calcium sulfate, cement, and aggregate with a maximum particle size of 1.2 mm or less. By containing calcium aluminate and calcium aluminosilicate, it becomes easier to obtain a spray material that has good setting properties even when combined with a liquid quick setting agent that does not contain fluorine. Further, by mixing the above five components, a spray material showing good strength can be obtained. Each component will be explained below.

(calcium aluminate)
Calcium aluminate according to the present embodiment is made of CaO and _Al2 , which is obtained by mixing raw materials containing calcia and raw materials containing alumina, and subjecting the mixture to heat treatment such as firing in a kiln or melting in an electric furnace. It is a substance whose main component is O ₃ and has hydration activity. Some of the calcium aluminates include alkali metal oxides, alkaline earth metal oxides, silicon oxides, titanium oxides, iron oxides, alkali metal halides, alkaline earth metal halides, alkali metal sulfates, and alkaline earth metal oxides. Similar metal sulfates and the like may be substituted, or these may be dissolved in solid solution. Examples of mineral forms include CaO.Al ₂ O ₃ (CA), 12CaO.7Al ₂ O ₃ (C ₁₂ A ₇ ), 3CaO.Al ₂ O ₃ (C ₃ A), and the like.

The particle size of the calcium aluminate is preferably such that the Blaine specific surface area (hereinafter referred to as the Blaine value) is 3,000 cm ² /g or more, and 5,000 cm ² /g or more in terms of rapid setting and initial strength development. It is more preferable that By being 3,000 cm ² /g or more, rapid setting properties and initial strength development properties can be improved. Further, the Blaine specific surface area is preferably 9,000 or less.

The CaO/Al ₂ O ₃ molar ratio of the calcium aluminate is preferably in the range of 0.5 to 3.0, more preferably in the range of 1.5 to 2.5. As long as the molar ratio is within the range, it can be used regardless of its form, such as crystalline or amorphous.

Calcium aluminate is preferably used in an amount of 1.0 to 5.0 parts by mass, preferably 1.5 to 3.0 parts by mass, per 100 parts of powder material for spraying, from the viewpoint of improving good rapid setting properties and strength development properties. More preferably, it is 5 parts by mass.

(calcium aluminosilicate)
The calcium aluminosilicate according to the present embodiment is a component that reacts with a liquid quick-setting agent to be described later to impart quick-setting properties at an early stage.
Calcium aluminosilicate is obtained by mixing a raw material containing calcia, a raw material containing alumina, and a raw material containing silica, and subjecting the mixture to heat treatment such as firing in a kiln or melting in an electric furnace. The main components are CaO, Al ₂ O ₃ and SiO ₂ , which is a general term for substances that have hydration activity. Some of these components include alkali metal oxides, alkaline earth metal oxides, titanium oxide, iron oxides, alkali metal halides, alkaline earth metal halides, alkali metal sulfates, and alkaline earth metal sulfates. Compounds substituted with can also be used. Although the crystal structure may be either crystalline or amorphous, it is preferable to use an amorphous structure because it provides high rapid setting properties.

The proportions of each component in 100 parts of calcium aluminosilicate are preferably 20 to 60 parts of CaO, 20 to 60 parts of Al ₂ O ₃ , and 6 to 50 parts of SiO ₂ , and 30 to 50 parts of CaO. , 30 to 50 parts of Al ₂ O ₃ and 10 to 30 parts of SiO ₂ are more preferable. When the ratio of each component is within this range, good rapid setting properties can be easily obtained.
Note that the total amount of CaO, Al ₂ O ₃ , and SiO ₂ in 100 parts of calcium aluminosilicate is preferably 86 parts or more, and preferably 90 parts or more.

The particle size of the calcium aluminosilicate is preferably 5,000 to 12,000 cm ² /g in Blaine value. When it is 5,000 cm ² /g or more, rapid setting properties and initial strength development properties are good, and when it is 12,000 cm ² /g or less, grinding efficiency is good and a stable Blaine value is easily obtained.

From the viewpoint of workability, initial strength development, and durability, the calcium aluminosilicate is preferably 0.5 to 5.0 parts, and 1.2 to 3 parts per 100 parts of the powder material for spraying. It is more preferable that

In this embodiment, the mass ratio of calcium aluminosilicate to calcium aluminate (calcium aluminosilicate/calcium aluminate) should be 0.5 to 1.0 from the viewpoint of improving rapid setting and strength development. is preferable, and more preferably from 0.6 to 0.8.

(calcium sulfate)
In this embodiment, strength can be improved by using calcium sulfate. Examples of calcium sulfate include anhydrite, hemihydrate gypsum, dihydrate gypsum, etc., and one or more types selected from these can be used. Anhydrite includes hydrofluoric acid byproduct anhydrite and natural anhydrite. Among these, it is preferable to use anhydrite because of its excellent strength development properties.

^{The particle size of calcium sulfate is preferably 3,000 to 10,000 cm 2 /g, more preferably 4,000 to 7,000 cm 2 /} g in Blaine value from the viewpoint of excellent rapid setting and strength development.

Calcium sulfate is preferably used in an amount of 1 to 10 parts, more preferably 1.5 to 5 parts, per 100 parts of the powder material for spraying, from the viewpoint of excellent strength development and prevention of strength reduction.

(cement)
The types of cement according to this embodiment include various types of Portland cement such as normal, early strength, super early strength, moderate heat, and low heat, and these Portland cements mixed with blast furnace slag, fly ash, or fine limestone powder. Examples include various mixed cements. Among these, it is preferable that the cement is an early-strength cement. The early-strength cement refers to a cement that exhibits better initial strength than ordinary Portland cement, and for example, early-strength Portland cement, fine particle cement containing fine particles of hydraulic powder, etc. can be used.

The amount of cement is preferably 20 to 55 parts, more preferably 30 to 50 parts, per 100 parts of the powder material for spraying, from the viewpoint of excellent initial strength development and powder pumpability.

(Aggregate with a maximum particle size of 1.2 mm or less)
In this embodiment, if aggregate with a maximum particle size of 1.2 mm or less is used as the aggregate, the pumping performance during spraying can be improved and rebound can be reduced. The type of aggregate is not particularly limited, and any of natural sand, silica sand, and lime sand can be used, and limestone is preferably used from the viewpoint of durability after spraying.

From the viewpoint of pumpability and durability during spraying, the amount of the aggregate is preferably 40 to 70 parts, more preferably 55 to 65 parts, per 100 parts of the powder material for spraying.

The particle size composition of the aggregate is not particularly limited, but the ratio of aggregate particle sizes of 0.6 to 1.2 mm and less than 0.6 mm is preferably 20:80 to 70:30 in mass ratio, More preferably 25:75 to 40:60. Within this range, excellent pumping properties can be easily obtained.

In addition, it is preferable that aggregate with a maximum particle size exceeding 1.2 mm is not included from the viewpoint of pumpability and rebound reduction, but in practice, 10 parts of powder material for spraying is required. It is preferably at most 5 parts, more preferably at most 5 parts, even more preferably at most 1 part, and most preferably 0 parts.
The particle size (maximum particle size) of the aggregate as described above can be adjusted by sieving.

In the powder material for spraying of this embodiment, the total content of calcium aluminate, calcium aluminosilicate, calcium sulfate, cement, and aggregate with a maximum particle size of 1.2 mm or less is such that the effects of these components are sufficiently From the viewpoint of exhibiting this effect, it is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.
Various additives used in the production of concrete can be appropriately included as long as the above content range is met.

[Spraying material]
The spraying material according to this embodiment includes the spraying powder material of the present invention described above and a liquid quick-setting agent that does not contain fluorine. That is, it consists of a combination of the powder material for spraying of the present invention and a liquid quick-setting agent, which are mixed immediately before spraying (mixed within 1 minute before spraying) or during spraying.

The liquid quick setting agent according to the present embodiment is used to react with cement or calcium aluminosilicate, promote initial setting, and further improve strength development. Here, the liquid quick setting agent does not contain fluorine.
Here, "not containing fluorine" means that the liquid quick-setting agent does not contain fluoride. Fluoride is a compound composed of fluorine and other elements or atomic groups, such as aluminum fluoride, calcium fluoride, sodium fluoride, and sodium aluminum hexafluoride.

The liquid quick-setting agent has quick setting power, good adhesion, low rebound rate, small amount of dust, good workability, and powder for spraying that prevents the initial strength from decreasing. It is preferable to use a material that contains aluminum sulfate as an rapidly forming component.

Aluminum sulfate is not particularly limited, and aluminum sulfate for industrial use, for paper manufacturing, or for water supply as specified in JIS A 1423 or JIS A 1450 can be used. The concentration of the aqueous aluminum sulfate solution is preferably 20 to 70%, more preferably 25 to 60%, from the viewpoints of scattering of the slurry during spraying, generation of precipitates in the aqueous solution, and viscosity of the aqueous aluminum sulfate solution. Note that the aluminum sulfate aqueous solution may be in a supersaturated state with aluminum sulfate.

The preferred blending ratio (mass ratio) of the powder material for spraying and the liquid quick-setting agent is the total amount X of calcium aluminate and calcium aluminosilicate in the powder material for spraying and the quick-setting component of the liquid quick-setting agent. The mass ratio (Y/X) to the solid content equivalent amount Y is preferably 0.2 to 0.5, more preferably 0.3 to 0.4. When the mass ratio (Y/X) is 0.3 to 0.4, good rapid setting properties and strength development properties can be imparted.

The method of spraying using the spraying material is not particularly limited, but from the viewpoint of workability, the powder material for spraying and the liquid quick-setting agent may be pumped separately and mixed immediately before spraying. is preferred. In this case, it is preferable to use a continuous mixer that continuously supplies water to the powder material for spraying, to pump the kneaded material, and to add a liquid quick-setting agent immediately before spraying.

The amount of water used for kneading is not particularly limited, but in order to obtain fluidity that allows pumping, for example, the water should be adjusted so that the flow value (according to JISR5201-1998) is 170 to 230. It is preferable to add

The pump that pumps the kneaded material is not particularly limited, and for example, a piston pump, squeeze pump, or snake pump can be used. Among these, from the point of view of workability, for example, the supplied spraying material is kneaded with water press-ined by a blade at the tip of the mixer, and then continuously pumped by a snake-type pump connected to the mixer. A method of kneading and force-feeding using a kneading and force-feeding device is preferable from the viewpoint of workability.

The pump for pumping the liquid quick setting agent is not particularly limited, but a piston type pump, squeeze type pump, snake type pump, etc. can be used.

The method of mixing the kneaded and pressure-fed material with the liquid quick-setting agent is not particularly limited, but the following methods may be mentioned. That is, when mixing the liquid quick-setting agent into the materials kneaded using the Y-tube, the liquid quick-setting agent can be conveyed by air and sprayed. Alternatively, an acidic liquid quick-setting agent pumped into an inlet piece having several holes around the ring may be injected with air, mixed with the kneaded material, and sprayed. Among these, a mixing method using an inlet piece is preferred from the viewpoint of mixability. In this case, the discharge rate is not particularly limited, but the discharge rate of the kneaded material is preferably 3 m ³ /h or less.

(Experiment example)
Calcium aluminate (CA), calcium aluminosilicate (CAS), calcium sulfate, cement cement, and aggregate are mixed using a Nauta mixer in the proportion shown in Table 1 to produce premix mortar as a powder material for spraying. did. The produced premix mortar was put into a G4 continuous mixer pump manufactured by PFT of Germany, water was added so that the water/premix mortar ratio was 20%, and the mixture was continuously kneaded and pumped at a capacity of 2 m ³ /hr. The specifications of the pressure feeding hose were a hose diameter of 1.25 inches and a hose length of 30 m. In addition, the liquid quick-setting agent shown in Table 1 was pumped with a plunger type pump, and the total amount of calcium aluminate and calcium aluminosilicate in the powder material for spraying and the liquid quick-setting agent (Experiments Nos. 1 to 13 were 27% aluminum sulfate aqueous solution (Experiment No. 14 is a fluorine-containing liquid quick-setting agent) so that the solid content equivalent amount of the quick-setting component (=aluminum sulfate or fluoride) becomes the mass ratio shown in Table 1. From the inlet piece attached in front of the nozzle, air of 3.5 kgf/ ^cm2 is added to the premix mortar that has been mixed with water, mixed to form a spray material, and the side wall (3.5 m high, 2.5 m wide) It was sprayed over an area of 1 ^m2 to a thickness of 2 cm on the side wall of a simulated tunnel.

<Materials used>
(1) Cement/Ordinary cement: Ordinary Portland cement, commercial product/Early strength cement: Early strength Portland cement, commercial product (2) Calcium aluminate (CA)
C ₁₂ A ₇ composition equivalent, CaO: 50, Al ₂ O ₃ : 45, amorphous, Blaine value 6000 cm ² /g
(3) Calcium aluminosilicate (CAS)
Calcium aluminosilicate (CAS): CaO: 43%, Al ₂ O ₃ : 43%, SiO ₂ : 14%, amorphous, Blaine value 6000 cm ² /g
(4) Calcium sulfate natural anhydrite, Blaine 5000cm ² /g
(5) Aggregate/Aggregate A: Dried lime sand from Itoigawa, Niigata Prefecture, maximum particle size 1.2 mm (0.6 to 1.2 mm: mixture mass ratio of less than 0.6 mm = 30:70)
・Aggregate A: Dried lime sand from Itoigawa, Niigata Prefecture, particle size 1.3 to 1.5 mm
(6) Liquid quick-setting agent: 27% aluminum sulfate aqueous solution (pH 2.7, commercially available)
・Fluorine-containing liquid quick setting agent (pH 2.6, F: 2.8%, commercially available)

<Evaluation>
The sprayed materials were evaluated as follows. The results are shown in Table 1.
- Mortar flow: The mortar flow of mortar kneaded with a continuous mixer pump was measured in accordance with JIS R 5201 "Physical Test Methods for Cement."
- Mortar hose blockage: Check for blockage of the mortar hose when starting the continuous mixing mixer pump and when material supply is stopped (during cleaning).
- Setting properties (setting test): The setting time (initial and final time) of the sprayed material was measured in accordance with JSCE D-102 “Appendix 3 Method for measuring setting time by penetration resistance of mortar added with quick-setting material” .
The first train time was marked ○ if it was within 2 minutes, △ if it was 3 to 5 minutes, and × if it was 6 minutes or more. The shorter the starting time, the better.
The completion time was rated ○ if it was within 5 minutes, △ if it was 6 to 10 minutes, and × if it was 11 minutes or more. The shorter the termination time, the better.
- Compressive strength: In accordance with JIS R 5201 "Physical test method for cement", the compressive strength of the sprayed material was measured for 3 hours and 28 days immediately after spraying.

INDUSTRIAL APPLICABILITY The present invention can be widely used as a powder material for various sprayed materials in the fields of civil engineering and construction.

Claims (3)

A powder material for spraying containing calcium aluminate, calcium aluminosilicate, calcium sulfate, cement, and aggregate with a maximum particle size of 1.2 mm or less. The powder material for spraying according to claim 1, wherein the cement is an early strength cement. A spraying material comprising the spraying powder material according to claim 1 or 2 and a fluorine-free liquid quick-setting agent.