JP3957665B2 - Spraying method - Google Patents

Description

  The present invention relates to a spraying material used when spraying cement concrete onto an exposed natural ground surface in a tunnel such as a road, a railway, and a water conduit, and a spraying method using the same.

Conventionally, in tunnel excavation, etc., primary lining using shotcrete has been performed, and after the ground has stabilized in this state, secondary lining is performed with regular concrete cast in place inside. ing.
On the other hand, in relatively hard ground where there are few cracks in the bedrock, secondary lining concrete may not be constructed and shotcrete may be used as permanent lining.
The finished product is called single shell lining, which is widely used in Scandinavia. In Japan, many studies have been made recently. However, in application, it is highly durable and watertight. Sex is required.

Generally, shotcrete has a large amount of unit cement and a large total amount of alkali.
Moreover, since the sand / aggregate ratio (s / a) is large, deterioration of concrete due to alkali aggregate reaction may be a problem.
When a reactive aggregate that is not harmless in the alkali aggregate reaction is used, the concrete may crack and durability may be impaired.
In addition, when there is spring water from the natural ground, the water tightness of the concrete decreases due to cracks, and there is a risk of water leaking inside the tunnel. For this reason, the spraying material which suppresses alkali-aggregate reaction is calculated | required.

  As a result of various studies to solve the above-mentioned problems, the present inventor has obtained knowledge that these problems can be solved by using a specific spray material, and has completed the present invention. .

That is, the present invention comprises (1) cement concrete obtained by mixing 100 parts of cement, 2-50 parts of shirasu having a Blaine specific surface area of 500 cm ² / g or more, and reactive aggregates that are not harmless in alkali aggregate reaction, 2) 8 to 20 parts of quick setting agent (100 parts of quick setting agent, 2 to 30 parts of alkali metal-containing material, 30 to 60 parts of calcium aluminate, 30 to 60 parts of plaster) and 100 parts of cement Spraying method characterized by mixing and spraying, wherein the cement concrete is mixed with water, and the alkali metal-containing substance is sodium aluminate, potassium aluminate and consists of one or more of the group consisting of sodium sulfate, calcium _{aluminate, 12CaO · 7Al 2 O 3,} 3CaO · Al 2 O 3, 11CaO · Al 2 O 3 · 1 of the group consisting of CaCl ₂ More than seeds, gypsum is anhydrous A該吹with method, characterized in that it.

  By using the spray material of the present invention, it is excellent in initial strength development and it becomes possible to suppress an alkali aggregate reaction (hereinafter referred to as ASR).

Hereinafter, the present invention will be described in detail.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.
Moreover, the cement concrete as used in this invention is a general term for cement mortar and concrete.

In the present invention, the alkali metal-containing substance contained in the quick setting agent (hereinafter referred to as an alkali substance) is not particularly limited as long as it contains an alkali metal element, for example, lithium, sodium, potassium, It may be a compound containing rubidium and cesium, in addition to those containing alkali metal elements such as fluoride, silicofluoride, and alum, oxides, chlorides, hydroxides of alkali metal elements, Nitrate, nitrite, phosphate, monohydrogen phosphate, dihydrogen phosphate, silicate, aluminate, sulfate, thiosulfate, sulfide, carbonate, bicarbonate, oxalate, And borate can be used, and one or more of these compounds can be used, and lithium, sodium, or potassium compounds that are easily available are preferred. The compounds of potassium are more preferred.
Although the usage-amount of an alkaline substance is not specifically limited, 2-30 parts are preferable in 100 parts of quick setting agents, and 3-20 parts are more preferable. If it is less than 2 parts, excellent quick setting may not be obtained, and if it exceeds 30 parts, the ASR suppression effect may not be obtained.

Calcium aluminate used in the present invention (hereinafter referred to as CA) is a mixture of CaO raw material, Al ₂ O ₃ raw material, etc., fired in a kiln, heat treated such as melting in an electric furnace, and pulverized Assuming that CaO is C and Al ₂ O ₃ is A, for example, C ₃ A, C ₁₂ A ₇ , C ₁₁ A ₇ · CaF ₂ , C ₁₁ A ₇ · CaCl ₂ , C ₂ A · These are indicated as SiO ₂ , CA, CA _{2 and the} like, and one or more of them can be used in combination.
Furthermore, it is also possible to contain Mg or Si as a mineralizer in which an alkali metal is dissolved.
As the CA, amorphous and crystalline materials can be used, and there is no problem that they are mixed.
The particle size of CA and its distribution are not particularly limited, but a specific surface area of brain (hereinafter referred to as “brane value”) of 2,000 cm ² / g or more is preferable in terms of initial strength development, and 3,000 cm ² / g or more is preferable. More preferred.

The gypsum used in the present invention is used in order to further improve the strength development of concrete, and specifically, anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum, one of these or Two or more types can be used.
The crystal form of gypsum is not particularly limited, and α-type hemihydrate gypsum, β-type hemihydrate gypsum, type I anhydrous gypsum, type II anhydrous gypsum, type III anhydrous gypsum, and the like can be used.
These gypsums include those produced in nature, waste gypsum obtained as industrial by-products, hydrofluoric acid by-product anhydrous gypsum, etc., and anhydrous gypsum is most preferred from its reactivity with cement and CA.
The gypsum particle size is preferably 3,000 cm ² / g or more in terms of brain value from the viewpoint of strength development.

The content ratio of the alkaline substance, CA, and gypsum in the quick setting agent of the present invention is not particularly limited, but in 100 parts of the quick setting agent, the alkaline substance is preferably 2 to 30 parts, and 3 to 20 parts. More preferred. Moreover, 30-60 parts is preferable and, as for CA, 35-55 parts is more preferable. Further, the plaster is preferably 30 to 60 parts, more preferably 35 to 55 parts.
If the content of the alkaline substance, CA, and gypsum in the quick setting agent is less than this range, excellent quick setting may not be obtained, and if it exceeds this range, long-term strength development may be impaired. .

  In the present invention, in addition to the components of the quick setting agent, for example, one or more known quick setting aids such as quick lime, slaked lime, aluminum hydroxide, siliceous fine powder, and fine powder having latent hydraulic properties are contained. It is also possible to make it.

  Although the usage-amount of a quick setting agent is not specifically limited, 6-20 parts are preferable with respect to 100 parts of cement, and 8-12 parts are more preferable from the surface of rapid setting property. If it is less than 6 parts, excellent quick setting may not be obtained, and if it exceeds 20 parts, improvement of the use effect cannot be expected.

  The cement used in the present invention is not particularly limited. Various ordinary Portland cements, such as normal, early strength, super early strength, and low heat, and these Portland cements include blast furnace slag, fly ash, limestone. Various kinds of mixed cement mixed with fine powder, silica or the like, or expanded cement or colloidal cement can be used.

The shirasu used in the present invention is a foam-like substance whose main component is volcanic glass at the time of volcanic eruption.
The chemical composition of shirasu is not particularly limited, but it is preferable to contain 40 to 80% of SiO ₂ and 5 to 25% of Al ₂ O ₃ as main components. In addition to these components, Na, K , Ca, Mg, Fe, and Ti can also be contained.
By containing Shirasu that is highly reactive with alkali, Shirasu and the alkali in the quick-set agent react at an early stage, so even when using aggregate with high reactivity of alkali aggregate, it can be used for long-term ASR . The resulting expansion can be reduced.
In terms of the particle size of the Silas ASR suppression, preferably 500 cm ² / g or more in Blaine value, 1,000 cm ² / g or more is more preferable. If it is less than 500 cm ² / g, an excellent ASR suppressing effect may not be obtained.
The amount of shirasu used is not particularly limited, but it is preferably used by replacing it with aggregate, and is preferably 2 to 50 parts, more preferably 3 to 10 parts relative to 100 parts of cement. If it is less than 2 parts, an excellent ASR suppressing effect may not be obtained, and if it exceeds 50 parts, strength development may be reduced.

In the present invention, it is preferable to use fibers in order to improve the impact resistance and elasticity of the hardened cement concrete formed using the spray material of the present invention.
As the fiber, either inorganic or organic can be used.
Examples of inorganic fibers include glass fibers, carbon fibers, rock wool, asbestos, ceramic fibers, and metal fibers. Organic fibers include vinylon fibers, polyethylene fibers, polypropylene fibers, polyacrylic fibers, cellulose fibers, Polyvinyl alcohol fiber, polyamide fiber, pulp, hemp and the like can be mentioned. Among these, metal fiber and vinylon fiber are preferable from the viewpoint of economy and effect.
The length of the fiber is preferably 50 mm or less, more preferably 30 mm or less, from the viewpoints of pumpability and mixing properties. If it exceeds 50 mm, the pumping tube may be blocked.
The amount of fiber used is preferably 0.5 to 3 parts by volume with respect to 100 parts by volume of cement concrete. If the amount is less than 0.5 part by volume, impact resistance and elasticity may not be improved. If the amount exceeds 3 parts by volume, the fluidity of cement concrete may be significantly impaired.

  In the present invention, in addition to the above materials, aggregates such as sand and gravel, AE agent, water reducing agent, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent, fluidizing agent, antifoaming agent, thickening agent 1 type or 2 or more types among an agent, a rust preventive agent, a defrosting agent, a shrinkage reducing agent, a polymer emulsion such as SBR and polyacrylate, a coagulation adjusting agent, and an expansion material do not substantially impair the object of the present invention. It is possible to use together in a range.

  In the spray material of the present invention, it is preferable that shirasu is mixed with cement concrete in advance, and the quick setting agent is mixed with cement concrete in a mixing tube before the spray nozzle.

  In the present invention, as an apparatus for mixing cement, aggregate, water, etc., an existing stirring apparatus can be used. For example, a tilting mixer, an omni mixer, a V-type mixer, a Henschel mixer, and a Nauta mixer can be used. It is.

As a method of mixing the quick setting agent, the powder quick setting agent is pneumatically fed and mixed with cement concrete, or it is made into a slurry by adding water to the quick setting agent to form a quick set slurry, which is mixed and mixed with cement concrete. There are methods, both of which can be used, but a method of slurrying is preferable from the viewpoint of reducing the amount of dust. In the case of slurrying, it is preferable to use a known retarder in combination from the viewpoint of improving the mixing property between the quick setting agent slurry and the cement concrete for spraying.
A common water pump can be used to add water to the powdered quick-setting agent, and a method of adding water together with compressed air is possible. Furthermore, in order to improve the mixing property, the junction of the quick setting agent and cement concrete can have a structure in which the shape of the tube and the inner wall are liable to be spiral or turbulent.

As the spray method of the present invention, a dry spray method or a wet spray method can be used.
As a dry-type spraying method, for example, there is a method in which cement and aggregate are mixed and pneumatically fed, water and a quick-setting agent are mixed and mixed and sprayed in a wet state, and as a wet-type spraying method, for example, There is a method in which cement, aggregate, and water are mixed in advance to form cement concrete, and this is pneumatically fed and a rapid setting agent is mixed and sprayed. Among these, since the amount of dust may increase in the dry spray method, it is preferable to use the wet spray method.
In the spraying method of the present invention, it is possible to use conventional spraying equipment and the like. The spraying equipment is not particularly limited as long as the spraying is sufficiently performed. For example, the product name “Ariva 280” manufactured by Ariva is used for pumping cement concrete, and the pumping of powder quick setting agent is used. The product name “Natom Cleat” manufactured by Chiyoda Seisakusho, etc., and the product name “Ankomat Pump” manufactured by Putmeister Co., Ltd. can be used for pumping the quick-setting agent slurry.
Moreover, it is preferable that the pressure of the compressed air which pumps the rapid setting agent is larger by about 0.01 to 0.3 MPa than the pumping pressure of the concrete so that cement concrete does not enter the pumping tube of the rapid setting agent and block the inside of the pressurized pipe. Further, the concrete pumping speed is preferably 4 to 20 m ³ / h.

Although the cement amount of the spray cement concrete used in the present invention is not particularly limited, it is preferably 300 kg / m ³ or more, and more preferably 18 N / mm ² or more at a compressive strength of 28 days of age. The slump value of the concrete for spraying is not particularly limited, but is preferably 5 cm or more, and is preferably 220 mm or more in flow value when the slump cone is pulled out.

Use a mixture of 60% water / cement ratio and 1/3 cement / sand ratio, and replace 100 parts of cement with the amount of shirasu shown in Table 1 for the aggregate. In contrast, mortar was prepared by adding 10 parts of a quick setting agent composed of an alkaline substance, CAi and gypsum shown in Table 1.
The prepared mortar was measured for dimensional change and proctor penetration resistance value at a test environment temperature of 20 ° C. The results are also shown in Table 1.

<Materials used>
Cement: Ordinary Portland cement, commercial product, total alkali amount 0.4%
Shirasu: Made by Shirakusu, brain value 3,000cm ² / g
Alkaline substance A: sodium aluminate, manufactured by Wako Chemical Co., Ltd., reagent grade 1 CA i: glass of C ₁₂ A ₇ composition, brain value 8,100 cm ² / g
Gypsum: anhydrous gypsum, brain value 4,000cm ² / g
Sand: Sanucitic pyroxene andesite, JIS A 5308 Annex 7 (Chemical method), dissolved silica amount is 750mmol / l, alkali concentration decrease is 200mmol / l, and it is judged as harmless.
Water: Tap water

<Measurement method>
Dimensional change: Measured according to JIS A1804 Aggregate Alkali Silica Reactivity Test Method (Rapid Method) Proctor penetration resistance: Measured according to JSCE D-102-1999, Age 3 minutes

  The test was conducted in the same manner as in Example 1 except that the quick setting agent having the composition ratio of Experiment N0.1-4 in Experimental Example 1 was used, and the alkaline substances and CAs shown in Table 2 were used. The results are also shown in Table 2.

<Materials used>
Alkaline substance B: Potassium aluminate, manufactured by Wako Chemical Co., Ltd., reagent grade 1 alkaline substance C: Sodium sulfate, manufactured by Wako Chemical Co., Ltd., reagent grade 1 CA: C ₃ A, crystalline, Blaine value 7,900 cm ² / g
CA C: C ₁₁ A ₇ · CaCl ₂ , crystalline, brane value 8,000cm ² / g

  The test was performed in the same manner as in Example 1 except that the bran shirasu shown in Table 3 was used and the quick setting agent having the composition of Experiment N0.1-4 in Experimental Example 1 was used. The results are also shown in Table 3.

  Tests were performed in the same manner as in Example 1 except that the quick setting agent having the composition of Test N0.1-4 in Experimental Example 1 was used and the amount of the quick setting agent shown in Table 4 was used with respect to 100 parts of cement. The results are also shown in Table 4.

Claims (3)

(1) 100cm cement and 500cm Blain specific surface area ² cement concrete made by mixing 2-50 parts of shirasu (50g / g or more) and reactive aggregates that are not harmless in alkali aggregate reaction; (2) 8-20 parts of quick setting agent (100% of cement) A spraying method characterized by mixing and spraying 2 to 30 parts of an alkali metal-containing substance, 30 to 60 parts of calcium aluminate, and 30 to 60 parts of gypsum) in 100 parts of the agent. The spraying method according to claim 1, wherein the cement concrete is mixed with water. The alkali metal-containing material is composed of one or more members selected from the group consisting of sodium aluminate, potassium aluminate and sodium sulfate, and calcium aluminate is 12CaO · 7Al. ₂ O _Three , 3CaO ・ Al ₂ O _Three , 11CaO ・ Al ₂ O _Three ・ CaCl ₂ The spraying method according to claim 1 or 2, wherein the gypsum is anhydrous gypsum.