JP4386810B2 - Spraying construction method using spraying material - Google Patents

Description

  The present invention relates to a spray material sprayed onto an exposed natural ground surface in a tunnel such as a road, a railway, and a water conduit, and a spray construction method using the same. The cement concrete of the present invention is a general term for cement paste, mortar, and concrete.

Conventionally, in order to prevent collapse of exposed ground such as tunnel excavation, a rapid setting concrete spraying method in which a quick setting agent is mixed with concrete has been performed (Patent Document 1). In this method, spray concrete is usually prepared at a cement, aggregate, and water metering plant installed at the excavation site, transported by an agitator car, pumped by a concrete pump, and joined at a midway. It is a method of mixing with a quick setting agent pumped from the other side with a pipe and spraying it as a quick setting sprayed concrete on a natural ground surface to a predetermined thickness.
The quick setting agent used at this time is composed of calcium aluminate, mainly composed of calcium aluminate and containing alkali aluminate or alkali carbonate, and does not contain calcium aluminate. The thing which has a salt and alkali carbonate as a main component is known (patent documents 2-5). Such a rapid setting agent has a function of promoting the setting of cement, and all of them are mixed with powder of cement concrete and sprayed on the ground surface as quick setting sprayed concrete. However, even if such a quick setting agent is used, it is difficult to obtain a sufficiently strong setting force and adhesion to the ground surface of the quick setting sprayed concrete. In such cases, there is a problem that the adhesion of this quick setting shotcrete is reduced and peeling easily occurs, and if the setting power or adhesion is poor, there is a problem that the rebound rate is increased. there were.
Japanese Patent Publication No. 60-4149 JP-A 64-51351 Japanese Patent Publication No.56-27457 JP 61-26538 A JP 63-210050 JP

On the other hand, the method of adding a quick setting agent to concrete usually has a problem that the amount of generated dust increases due to powder mixing by pneumatic transportation, so that the working environment becomes poor and the generation of pneumoconiosis is a concern. It was. Therefore, as a method of reducing the rebanding rate and the amount of dust generated, there is a method in which a quick setting agent is slurried, mixed and added to cement concrete, and further, a solution in which alkali metal aluminate is dissolved is individually pumped and sprayed. Proposed (Patent Document 6). However, since this method uses a highly alkaline liquid, there remains a problem in terms of handling.
On the other hand, a quick setting method has been proposed in which a quick setting agent is slurried and alum is mixed with cement concrete to improve the working environment (Patent Document 7). However, at present, this construction method is not yet satisfactory, and its improvement has been strongly desired.
JP-A-5-139804 JP-A-5-97491

The present invention is intended to solve the above problems, can be reduced rebound during spraying, further, it is an object to provide a spray construction method using the spray materials that dust is reduced.

As a result of various studies on the above problems, the present inventors have obtained knowledge that the above problems can be solved by using a specific spraying material, and have completed the present invention.
That is, the present invention is a method for spraying a spray material comprising cement concrete and a quick setting agent slurry, wherein the quick setting agent slurry is 20 parts by weight relative to 100 parts by weight of calcium aluminate and calcium aluminate. Prepared by blending cellulose and 40-300 parts by weight of water to 100 parts by weight of a quick setting agent containing -200 parts by weight of gypsum and 0.5-20 parts by weight of a setting accelerator and a setting retarder The naphthalene sulfonic acid formalin condensate in an amount of 0.05 to 5 parts by weight (solid content) with respect to 100 parts by weight of cement and the cellulose to 0.001 part with respect to 100 parts by weight of cement 0.5 parts by weight were mixed separately quick-slurry side in an amount of, blowing the said cement concrete quick-slurry pumping separately, characterized Rukoto spraying joins mixed with Y-shaped tube The spraying construction method is characterized in that the cement concrete contains alum as a sulfate in a ratio of 0.3 to 7 parts by weight with respect to 100 parts by weight of cement .

  By performing the spraying method using the spraying material of the present invention, the rebound at the time of spraying can be reduced and the dust can be reduced compared to the conventionally used powder quick-setting agents. Is improved. Moreover, since high intensity | strength expression can be anticipated in the initial stage and long term rather than the conventional spraying method, spraying thickness can be made thin and construction cost can also be reduced. Moreover, since high intensity | strength is obtained in the spraying initial stage, safety | security improves.

  Hereinafter, the present invention will be described in detail.

Examples of the cement used in the present invention include various ordinary Portland cements such as ordinary, early strength, and ultra early strength, and various mixed cements obtained by mixing fly ash, blast furnace slag, and the like with these Portland cements. These can be used in the form of fine powder. A suitable cement can be selected depending on the performance and construction conditions such as rebound rate and dust reduction, pumpability, and strength development required for spray construction. And the use of early strength Portland cement is preferred. Also, fluoro cements containing fluoro calcium aluminate also can be used as a cement in the present invention, _{furthermore, 3CaO · SiO 2, 2CaO ·} SiO 2, 3CaO · Al 2 O 3, and 4CaO · Al ₂ O ₃ · Fe A special cement in which potassium sulfate, sodium sulfate, calcium sulfate and the like are blended with a cement clinker fired by changing the content of the mineral composition in the cement indicated as ₂ O ₃ can also be used as a cement in the present invention.

  In the present invention, it is preferable to add a sulfate to the cement in advance from the viewpoint of increasing the strength of the quick setting sprayed concrete in which the concrete and the quick setting agent slurry are mixed.

  As the sulfate, gypsum, alum, aluminum sulfate, sodium sulfate, and the like can be used, and gypsum, alum, and aluminum sulfate are preferably used.

Examples of the gypsum include anhydrous gypsum, semi-water gypsum, and two-water gypsum, and these can be used alone or in combination. Among these, anhydrous gypsum is preferable in terms of strength development. The particle size of gypsum is usually about the level used in cement, for example, about 3,000 cm ² / g in terms of the brain value, and more preferably finely powdered so as to exceed 3,000 cm ² / g. The amount of gypsum used is preferably 1 to 25 parts by weight and more preferably 5 to 20 parts by weight with respect to 100 parts by weight of cement. If it is less than 1 part by weight, it may be difficult to promote long-term strength. If it exceeds 25 parts by weight, the initial setting will be delayed, the adhesion to the ground will be reduced, or the concrete will break down due to long-term expansion. There is a case.

Alums include alum and alum stones. Examples of alum include potash alum, chrome alum, and iron alum. Alumite is a natural product that has a composition of [(K, Na) (Al, Fe) ₃ (SO ₄ ) ₂ (OH) ₆ ]. It is possible to use calcined alumite powder that has been calcined at 800 ° C. or lower and pulverized. Of these, it is preferable to use a commercially available potash alum. The amount of alum used is preferably 0.3-7 parts by weight, more preferably 0.5-5 parts by weight, and most preferably 1-3, with respect to 100 parts by weight of cement. If it is less than 0.3 part by weight, it may be difficult to promote short-term strength development and long-term strength development. If it exceeds 7 parts by weight, it is difficult to secure the cementing work time and to secure the working time. It may expand and destroy concrete.

  Furthermore, it is preferable to use anhydrous aluminum sulfate which is generally commercially available. The amount of aluminum sulfate used is preferably 0.3-7 parts by weight and more preferably 0.5-5 parts by weight with respect to 100 parts by weight of cement. If it is less than 0.3 part by weight, it may be difficult to promote short-term strength development and long-term strength development. If it exceeds 7 parts by weight, it is difficult to secure the cementing work time and to secure the working time. It may expand and destroy concrete.

  As the cement concrete of the present invention, it is possible to use either dry cement concrete in a dry state in which water is not mixed or cement concrete in which water is mixed.

  The amount of water used in the cement concrete of the present invention is preferably 35 to 65%, more preferably 40 to 55% in terms of water / cement ratio (W / C). If it is less than 35%, it is difficult to knead sufficiently with a mixer, and if it exceeds 65%, it is difficult to obtain strength, and the amount of the quick setting agent may be increased.

  In the present invention, the quick setting agent used in the form of a slurry is a quick setting component that causes cement to set in the initial stage, and is not particularly limited. From the aspect, those containing calcium aluminate as a main component are preferable.

Here, calcium aluminate is obtained by mixing calcia raw materials, alumina raw materials, etc., heat treatment such as baking in kiln or melting in electric furnace. Mineral composition is 3CaOAl ₂ O ₃ (C ₃ A), 12CaO • 7Al ₂ O ₃ (C ₁₂ A ₇ ), CaO • Al ₂ O ₃ (CA), CaO • 2Al ₂ O ₃ (CA ₂ ), etc. Examples thereof include crystalline and amorphous materials obtained by cooling and pulverizing the heat treated calcium aluminate as a component, and it is also possible to use one or more of these in combination. In addition, as other mineral components, calcium aluminate partially containing alkali metals such as sodium, potassium and lithium, and the total of calcined calcium aluminate is 70% by weight or more and sodium aluminate is 20% by weight. Hereinafter, a calcined product containing 10% by weight or less of unreacted CaO can be used as the calcium aluminate of the present invention. Among these, in view of reaction activity, it is preferable to use amorphous calcium aluminate obtained by quenching the heat-treated product corresponding to the C ₁₂ A ₇ mineral composition. 11CaO ・ 7Al ₂ O _{3 in} which one CaO of calcium aluminosilicate such as metallurgical slag containing three components of CaO, Al ₂ O ₃ and SiO ₂ and C ₁₂ A ₇ is replaced with a halide such as CaF ₂ · CaX ₂ (X is a halogen such as _{fluorine), CaO, Al 2 O 3} , and sO ₃ of _{3 4CaO · 3Al 2 O 3 ·} sO 3 containing components, as well, used in the same manner as the alumina cement also calcium aluminate Is possible. The particle size of calcium aluminate is preferably 3,000 cm ² / g or more in terms of brain value, and more preferably 4,000 cm ² / g or more from the viewpoint of rapid setting and initial strength development. If it is less than 3,000 cm ² / g, rapid setting and initial strength development may be reduced.

In the present invention, gypsum and a setting accelerator can be used in combination with calcium aluminate in terms of improving the initial setting and strength development.

  The amount of gypsum blended on the quick setting agent side is preferably 20 to 200 parts by weight, more preferably 50 to 150 parts by weight per 100 parts by weight of calcium aluminate. If it is less than 20 parts by weight, strength development may be reduced, and if it exceeds 200 parts by weight, the initial setting force may be reduced.

  The setting accelerator used in the present invention refers to an agent that accelerates the setting of cement concrete. Specifically, alkali metal aluminate, alkali metal carbonate, alkali metal hydroxide, slaked lime, and sodium sulfate. , Potassium sulfate, sulfates such as aluminum sulfate, and the like, and one or more of them can be used. Examples of the alkali metal aluminate include lithium aluminate, sodium aluminate, and potassium aluminate, and one or more of these may be used in combination. Among these, sodium aluminate is preferable in terms of promoting initial setting. Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate. One or more of these may be used in combination. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide, and one or two or more of these may be used in combination. Examples of sulfates include sulfates such as sodium sulfate, potassium sulfate, magnesium sulfate, and aluminum sulfate, and gypsums such as double salts such as alum, and these may be used alone or in combination. May be. Among the setting accelerators, alkali metal aluminates and / or alkali metal carbonates are preferable in terms of promoting initial setting. The blending amount of the setting accelerator in the rapid setting agent is preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of calcium aluminate. If it is less than 0.5 parts by weight, there is no blending effect, and if it exceeds 20 parts by weight, the long-term strength development may be reduced.

  The used amount of the quick setting agent is preferably 2 to 25 parts by weight, more preferably 5 to 20 parts by weight with respect to 100 parts by weight of cement. If it is less than 2 parts by weight, it may be difficult to promote the initial setting, and if it exceeds 25 parts by weight, long-term strength development may be inhibited.

  In the present invention, the rapid setting agent is slurried and mixed with cement concrete from the viewpoints of dust generation prevention, improvement of mixing with cement concrete, and reduction in quality variation. Although the usage-amount of water is not specifically limited, 40-300 weight part is preferable with respect to 100 weight part of quick setting agents, and 50-100 weight part is more preferable. If the amount is less than 40 parts by weight, the fluidity of the quick setting agent slurry is small, which may hinder the pumpability when pumping. If the amount exceeds 300 parts by weight, the addition amount of the quick setting slurry increases. Therefore, the amount of water with respect to the cement becomes too large, which may hinder the strength development.

  In the present invention, naphthalene sulfonic acid formalin condensate and celluloses are added to the cement concrete side and the quick setting agent slurry side from the viewpoint of improving adhesion at the time of spraying, reducing the amount of dust generated, and reducing the rebound rate. Blend separately. That is, naphthalenesulfonic acid formalin condensate is blended on the cement concrete side, and celluloses are blended on the rapid setting agent slurry side.

  The naphthalene sulfonic acid formalin condensate (hereinafter referred to as NS) used in the present invention has the purpose of improving the fluidity of cement concrete and the dispersion stability of the quick setting agent slurry, and reacts with celluloses to increase the viscosity. It is used for the purpose of improving the adhesion of the resin and reducing dust and rebound. Either liquid or powder can be used. The amount of NS used is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of cement as a solid content. If it is less than 0.05 part by weight, there is no effect, and if it exceeds 5 parts by weight, strength development may be inhibited.

  Cellulose has the effect of improving the pumpability of cement concrete, reducing rebound, and suppressing dust generation, and is used as a component of a dust reducing agent for shotcrete. In the present invention, since NS is blended on the cement concrete side, celluloses are blended on the rapid setting agent slurry side. Examples of celluloses include cellulose ethers such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, and hydroxyethylethylcellulose. One or more of these may be used in combination. Is also possible. The amount of cellulose used is preferably 0.001 to 0.5 parts by weight, more preferably 0.005 to 0.1 parts by weight, per 100 parts by weight of cement. If it is less than 0.001 part by weight, there is no effect, and if it exceeds 0.5 part by weight, the strength development of shotcrete may be hindered.

  In the present invention, it is possible to further use one or two or more kinds selected from a setting retarder, fine powder, and fiber in accordance with each purpose in cement concrete and / or rapid setting agent slurry.

  Here, the setting retarder is an agent that delays the setting of the cement, and is important as a setting retarder for maintaining the kneading time of the rapid setting agent slurry when slurrying the rapid setting agent. Specifically, organic acids, alkali carbonates, phosphates, alcohols and the like can be mentioned. Examples of the organic acids include citric acid, tartaric acid, gluconic acid, malic acid, and lactic acid, or sodium salts and potassium salts thereof, and one or more of these may be used in combination. Of these, citric acid is preferred because it is difficult to inhibit strength development. Examples of phosphates include sodium salts and potassium salts such as monophosphate, diphosphate, triphosphate, tripolyphosphoric acid, hexametaphosphoric acid, pyrophosphoric acid, and tetrapolyphosphoric acid. You may use together. Among these, sodium tripolyphosphate is preferable because it is difficult to inhibit strength development. Examples of alcohols include monohydric alcohols such as methanol and ethanol, polyhydric alcohols such as ethylene glycol and glycerin, and water-soluble polymer polyols having a hydroxyl group such as polyethylene glycol and polypropylene glycol. The use amount of the setting retarder is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight with respect to 100 parts by weight of the rapid setting agent. If the amount is less than 0.01 parts by weight, the effect may not be obtained. If the amount exceeds 5 parts by weight, dripping occurs immediately after spraying, which may impair strength development.

  The fine powder is one that reduces the unit amount of the cement, the amount of dust, and the rebound rate, and improves the pumpability of the cement concrete. The average particle size is 10 μm or less, and the maximum particle size is preferably 20 μm or less. Specifically, fine powder slag, fine powder fly ash, bentonite, kaolin, fine powder calcium carbonate, silica fume and the like may be mentioned, and one or more of these may be used in combination. Among these, it is preferable to use silica fume in terms of strength development. In the present invention, it is also possible to use fine powder having an average particle diameter exceeding 10 μm. The amount of fine powder used is preferably 1 to 100 parts by weight and more preferably 2 to 30 parts by weight with respect to 100 parts by weight of cement. If it is less than 1 part by weight, there is no effect in terms of long-term strength development, and if it exceeds 100 parts by weight, the setting and curing may be delayed.

  The fiber has an effect of improving the impact resistance and toughness of cement concrete, and any of inorganic fiber and organic fiber can be used. Examples of the inorganic fiber include glass fiber, carbon fiber, rock wool, asbestos, ceramic fiber, and metal fiber, and examples of the organic fiber include vinylon fiber, polyethylene fiber, polypropylene fiber, polyacrylic fiber, cellulose fiber, and polyvinyl alcohol. Examples thereof include fibers, polyamide fibers, pulp, hemp, wood wool, and wood chips. Among these, metal fiber and vinylon fiber are preferable in terms of economy. The length of the fiber is preferably 30 mm or less in consideration of pumpability and mixing properties. The amount of fiber used is preferably 0.5 to 2 parts by volume, more preferably 0.7 to 1.5 parts by volume with respect to 100 parts by volume of cement concrete. If it is less than 0.5 volume part, there is no effect, and if it exceeds 2 volume parts, there is a possibility of impairing the pumpability and strength development of sprayed concrete.

  In the present invention, it is possible to use either a dry spraying method or a wet spraying method, and it is possible to spray as paste, mortar, and concrete because of required physical properties, economy, and construction properties.

  Aggregates such as fine aggregates and coarse aggregates used in the present invention preferably have low water absorption and high aggregate strength, but are not particularly limited. Examples of coarse aggregate include river gravel, mountain gravel, and lime gravel. Examples of the fine aggregate include river sand, mountain sand, lime sand, and quartz sand. The fine aggregate ratio is preferably 70% or more from the viewpoint of reducing the rebound ratio, and the maximum aggregate dimension of the coarse aggregate is preferably 10 mm or less from the viewpoint of reducing the rebound ratio.

  In the spraying method used in the present invention, it can be sprayed as cement concrete in view of the required physical properties, economy, workability and the like. As the spraying method, a spraying method in which cement concrete and a quick setting agent slurry are separately pumped and the quick setting sprayed cement concrete that has been mixed and mixed is preferably sprayed, and a dry spraying method or a wet spraying method can be used. Among these, the wet spraying method is preferable in terms of the generation amount of dust. As a dry spray method, cement, gypsum, and aggregate are mixed and pneumatically fed. In the middle, for example, two Y-tubes are connected, and water is added from one side and then a quick setting slurry is added in that order. And a method of spraying in a wet state. As a wet spraying method, cement, gypsum, aggregate, and water are mixed and kneaded, and pneumatically fed. In the middle, for example, a method of spraying by adding a quick-setting agent slurry from one side of a Y-shaped tube, etc. Can be mentioned.

Cement 400 kg / m ^3, water 200 kg / m ^3, with a concrete mix of fine aggregate 1,390kg / m ^3, and coarse aggregate 370 kg / m ^3, relative to 100 parts by weight of cement, and b2 parts by weight of sulfuric acid salt, Shotcrete was produced by blending NS shown in Table 1.
1m ³ of the sprayed concrete produced was pneumatically fed by a concrete pressure pump, Arriver 280.
On the other hand, the cellulose α shown in Table 1 and 50 parts by weight of water were blended with 100 parts by weight of the quick setting agent B and mixed with a continuous mixer to prepare a quick setting agent slurry.
The spray concrete and the quick set slurry are separately pumped, combined and mixed with a Y-shaped tube, so that the quick setting agent is 15 parts by weight in solids with respect to 100 parts by weight of cement in the shotcrete. We sprayed the side of a simulated tunnel with a height of 3.5m and a width of 2.5m produced in an arch shape, and measured the rebound rate, the amount of dust, and the compressive strength. The results are also shown in Table 1.

<Materials used>
Cement: Ordinary Portland cement, commercial product, specific gravity 3.16
Fine aggregate: River sand from Himekawa, Niigata Prefecture, specific gravity 2.61
Coarse aggregate: River sand from Himekawa, Niigata, surface dry state, specific gravity 2.65, Gmax 10mm
Cellulose α: methyl cellulose, commercial product NS: commercial product
C ₁₂ A ₇ : calcium aluminate, amorphous, synthetic anhydrous gypsum: commercial product, Blaine specific surface area 5,800 cm ² / g
Quick setting agent B: C ₁₂ A ₇ / anhydrous gypsum / sodium aluminate / citric acid weight ratio 5/5/1 / 0.2 mixed product, specific gravity 2.88
Sulfate b: Potash alum, commercial product

<Measurement method>
Rebound ratio: The quick-setting property Shotcrete poppy 1 m ³ sprayed at a spray rate of 4m ³ / h, after spraying was completed, the amount of quick-setting property Shotcrete dropped to vinyl sheet lined on the floor without adhering measurement The rebound rate was calculated from the formula: (weight of shotcrete dropped without adhering during spraying) / (total amount of quick setting shotcrete used for spraying) × 100 (%).
Dust amount: Measured at a fixed position of 3m from the spraying location 10 minutes after spraying. Compression strength: The compressive strength of the material is 1 hour and 1 day. Pull out the pin installed in the pullout formwork 25cm wide x 25cm long Cover the surface of the formwork with quick setting spray concrete, pull out the pin from the backside of the formwork, determine the pullout strength at that time, and calculate the compressive strength from the formula of compressive strength = (pullout strength) x 4 / (test specimen contact area) The compressive strength after the age of 7 days is determined by spraying quick setting sprayed concrete onto a 50cm wide x 50cm long x 20cm thick formwork, and the collected specimen of 5cm diameter x 10cm length is 20 tons pressure resistant. The compressive strength was determined by measuring with a machine.

Claims (2)

A method for spraying a spray material comprising cement concrete and a quick setting agent slurry, wherein the quick setting agent slurry is 20 to 200 parts by weight of calcium aluminate and 100 parts by weight of calcium aluminate. And 0.5 to 20 parts by weight of a setting accelerator, and 100 parts by weight of a quick setting agent containing a setting retarder, prepared by blending cellulose and 40 to 300 parts by weight of water, and Naphthalenesulfonic acid formalin condensate at a ratio of 0.05 to 5 parts by weight (solid content) with respect to 100 parts by weight of cement, and cellulose at a ratio of 0.001 to 0.5 parts by weight with respect to 100 parts by weight of cement in mixed separately quick-slurry side, wherein the cement concrete rapid setting admixture slurry pumping separately spraying construction wherein the Rukoto spraying joins mixed with Y-shaped tube. The cement concrete alum such as the sulphate, spraying construction method according to claim 1, characterized by containing in a proportion of 0.3 to 7 parts by weight per 100 parts by weight of cement.