JP2003306362A - Powdery quick setting agent for shotcrete and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powdery quick setting agent for shotcrete with low floating dust generation at a shotcrete work and having no trouble for its pressure transportation when transported or supplied in a quick setting agent supplying apparatus, and its producing method. <P>SOLUTION: The powdery quick setting agent for shotcrete contains a granular aggregate combined with a quick setting particle through a combinative component and is characterized in that the combinative component is not practically existing on a granular aggregate surface. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quick-setting admixture for use in shotcrete, in particular a powder-like quick-set admixture capable of reducing the amount of dust generated during spraying, and a powder quick-setting admixture for it. The present invention relates to a method for producing an agent.

[0002]

2. Description of the Related Art In construction work for excavated tunnels and underground spaces, it is widely practiced to spray concrete on the exposed surface of the excavation to prevent the exposed surface from collapsing.

As a concrete spraying method, a wet method and a dry method are known. In the wet method, an uncured concrete kneaded product is pressure-fed through a transportation pipe, blown out from a spray nozzle at the tip, and concrete is sprayed on the exposed surface for lining. If the base concrete alone has poor adhesiveness and the sprayed object is dripping, especially if the sprayed thickness is thick, the sprayed object may drop due to its own weight. The agent is added during the pressure-feeding of the base concrete to give the concrete a quick-setting property. Similarly, in the dry method considering giving quick setting property to concrete, the mixed powder of aggregate, cement and quick setting agent is sprayed from the spray nozzle to the exposed surface, and the water is pumped separately to the exposed surface for excavation. It is sprayed and lined.

Conventionally, as a quick-setting agent used for wet shotcrete, a powder quick-setting agent containing calcium aluminate mineral as a main component and an aqueous solution of aluminate, alkali carbonate, aluminum sulfate or the like as a main component has been used. It is known that there are liquid quick-setting agents. The spraying method using the powder quick-setting admixture has an advantage that the quick-setting property is superior to the case where the liquid quick-setting admixture is used. On the other hand, since the quick-setting agent is a powder, there is a drawback that the quick-setting agent powder is generated as dust. Further, in general, the dry method produces a larger amount of dust when sprayed than the wet method, so that the wet method has become the mainstream of concrete spraying today. However, even in the wet method, since the quick-setting agent is generally added to the base concrete that is being fed at high speed, the mixed state of the two is not necessarily sufficient, and the quick-setting agent powder remaining without being mixed is blown out as it is. Although the amount of dust generated is smaller than that of the dry method, dust is likely to be suspended for a long time at a closed work site such as a tunnel.

For this reason, a method is known in which a thickening agent or the like is added to the base concrete so that the powdered quick-setting agent can be easily taken into the base concrete. Many are not taken in and are blown out as they are. On the other hand, by adding thickeners and binders to the quick-setting agent itself to form agglomerates in which fine powder particles that become dust are coagulated and adhered, and the generation of airborne dust can be suppressed by reducing the fine particles that exist as individual particles as much as possible. there is a possibility. However, with the quick-setting admixture containing the binding component, if the addition amount is effective for reducing the fine powder content, the granulation is likely to proceed, and as a result, the pressure-feeding load increases when the conventional quick-setting admixture feeder is used. As a result, the supply amount is restricted, and further, the quick-setting agent is likely to adhere to the inside of the supply device or the spraying device, and if it is solidified as it is, the inside of the supply / transport pipe may be blocked.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, that is, a powder quick-setting admixture for sprayed concrete that does not hinder the pressure-feeding property during supply and transportation, and has less floating dust, and the spraying. An object of the present invention is to provide a relatively simple manufacturing method for a powder quick-setting admixture for concrete.

[0007]

Means for Solving the Problems As a result of intensive investigations by the present inventors in order to obtain a solution to the above-mentioned problems, as a result of an increase in the pressure-feeding load of the quick-setting admixture supplying device for the quick-setting admixture to which a binding component has been added, It was found that the adhesion in the supplying device and the spraying device was mainly due to the binding component remaining on the surface of the quick-setting powder, and the following means (1) and (2) were taken. This problem has been solved by the powder quick-setting admixture for spraying concrete and the method for producing a powder quick-setting admixture for spraying concrete by taking the means of (3) to (4).

That is, the present invention provides (1) a powdered quick-setting admixture for spraying concrete, which comprises a granular aggregate in which quick-setting particles are bonded and formed via a binding component, A powder quick-setting admixture for shotcrete, characterized in that the binding component is substantially absent on the surface of the body. (2) The powder quick-setting admixture for sprayed concrete according to (1) above, which contains quick-setting single particles that do not form a granular aggregate and that does not substantially have a binding component on the surface. (3) After spray-adding the liquid binding component to the quick-setting particles, one or more of quick-setting powder, powdery water reducing agent, shirasu balloon, silica fume, and activated clay mineral powder is added and mixed. A method for producing a powdered quick-setting admixture for shotcrete, characterized in that
(4) The addition amount of any one or more of the quick-setting powder, powdered water reducing agent, shirasu balloon, silica fume, and activated clay mineral powder of (3) above is based on 100 parts by weight of the quick-setting particles. 1 to 20 parts by weight of a method for producing a powdered quick-setting admixture for shotcrete.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The quick-setting particles constituting the powder quick-setting admixture for sprayed concrete of the present invention may be particles having a quick-setting component as a main component which can give quick-setting property to mortar or concrete. For example, its chemical composition and structural state are not limited.
For example, calcium aluminate-based composition, calcium sulfaluminate-based composition, calcium-sodium-aluminate-based composition, calcium-fluoro-
There are aluminate-based compositions, ≡ calcined alunite, and the like, and the state thereof may be a compound, a solid solution, an amorphous body, or a mixture of two or more thereof. Further, the quick-setting particles may contain a component other than the quick-setting component, for example, a quick-setting promoting component.

The powder quick-setting admixture for shotcrete of the present invention comprises a granular aggregate in which a plurality of the quick-setting particles are bonded and formed via a binding component. This binding component is a chemical substance that differs in chemical composition from the quick-setting particles themselves, and has the ability to bond or bond the quick-setting particles to each other through the interposition of this chemical substance. If it is, it will not be specifically limited. To give a specific example,
Acrylic acid or its salt, polyacrylic acid salt, methacrylic acid, acrylic acid-acrylic acid ester copolymer, acrylic acid-acrylic acid ester-methacrylic acid ester copolymer, methacrylic acid-acrylic acid ester-methacrylic acid ester copolymer Combined, acrylic acid-methacrylic acid-acrylic acid ester copolymer, acrylic acid-methacrylic acid-
Methacrylic acid ester copolymer, acrylic acid-methacrylic acid-acrylic acid ester-methacrylic acid ester copolymer, acrylic acid salt-acrylamide copolymer, ethyl cellulose, methyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl Methyl cellulose, hydroxyethyl ethyl cellulose, dimethylaminoethyl methacrylate, carboxymethyl cellulose, carboxymethyl cellulose sodium salt,
Polydimethyldiallylammonium salt, starch-acrylic acid-sodium acrylate copolymer, vinyl acetate, vinyl acetate-sodium maleate copolymer, vinyl acetate-
Ethylene copolymer, vinyl acetate-ethylene-vinyl chloride copolymer, vinyl acetate-ethylene-acrylic acid ester copolymer, vinyl acetate-ethylene-methacrylic acid copolymer, polyacrylamide, Mannich modified product of polyacrylamide, polyethylene Oxide, polyvinyl alcohol, methyl polymethacrylate, guar gum or modified products thereof, casein, sodium alginate, starch, glucomannan, arabinan, arabinogalactan, naphthalenesulfonate, ligninsulfonate, polycarboxylate, alkylallylsulfone Acid salt, melamine sulfonate, naphthalene sulfonic acid-formalin condensate, alkylnaphthalene sulfonic acid-formalin condensate, phenol sulfonate-formaldehyde condensate, vinyl sulfonate Formaldehyde condensate, dibutylphthalol, tributyl phosphate, alkylphenol, polyglycol, polyoxyethylene, polyoxypropylene, diethylene glycol, triethylene glycol, polyethylene glycol, alkylene oxide adduct of lower alcohol, polytetrafluoroethylene, dimethyl silicone, modified Silicone, glycerin, propylene glycol, polypropylene glycol, epoxy resin, liquid paraffin, fats and oils containing paraffinic hydrocarbons as a main component or a mixture of the oils and fats and emulsifiers such as dodecyl polyoxyethylene ether, and naphthenic hydrocarbons as a main component. Or a mixture of the oil and fat with an emulsifier such as dodecyl polyoxyethylene ether. Incidentally, in order to avoid the hydration reaction between the quick-setting component and the binding component, it is preferable that the amount of the mixed water in the binding component is as small as possible, and the water excluding the structural water in the binding component should be removed. The water content is 0.
It is preferably 5% by weight or less.

In the powdered quick-setting admixture for shotcrete of the present invention, it is desirable that the binding component is not present on the surface of the granular aggregate as much as possible. When the binding component is present on the surface of the granular aggregate, the granular aggregates are adhered to each other and coarsening proceeds excessively, the powder property is lost and the fluidity at the time of pumping the quick-setting agent is lowered, or the base concrete is Dispersibility into
There is a possibility of adhesion within the quick-setting agent supply device. However, in the present invention, it is not necessary to completely eliminate the binding component exposed and remaining on the surface of the granular aggregate, and the presence of a very small amount, which almost never leads to the occurrence of such a phenomenon, is allowed. As a standard for this minute amount, the surface area of the binding component exposed on the surface of the granular aggregate may be a value of about 1% or less of the surface area of the granular aggregate. In addition, even if a large amount of binding component remains on the surface of the granular aggregate during the manufacturing process, the binding on the surface at room temperature for an extremely short time is accompanied by changes in the structural state, changes in the chemical composition, and volatilization of volatile components. As long as it does not affect the quick-setting property, the surface residue will not be a binding component as long as it almost completely loses its properties and adhesiveness.
Its presence is acceptable regardless of the amount. In the present invention, the phrase "the binding component is substantially absent on the surface of the granular aggregate" means a substance containing these points.

Further, considering that the floating dust generated during the spraying is mainly derived from the fine powder component of the quick-setting admixture, the coarse particle portion of the quick-setting admixture, that is, the single particles of approximately 7 μm or more are granular aggregates. The particles may be present as they are without forming the particles. This is because even if the particles are not taken into the base concrete during spraying, the coarse particles do not become floating dust.
This is because it falls in an extremely short time. Also for such coarse-grained particles, it is desirable that the same components as the binding components involved in the formation of the granular aggregate are not present on the surface of the quick-setting single particles for the same reason as the above-mentioned granular aggregate. Therefore, the powdered quick-setting admixture for sprayed concrete of the present invention contains the above-mentioned granular aggregate, and also contains the quick-setting single particles that do not form the granular aggregate and that the binding component is not substantially present on the surface. It may be one. Here, the quick-setting single particles having substantially no binding component on the surface have the same meaning as in the case of the above-mentioned granular aggregate. Further, the granular aggregate coexisting with the single particles is preferably composed of a combination of fine powders, but in the case where the particle size distribution is wide, it is not easy to selectively bond only the fine powders, and thus to the floating dust. Fine particles may include a granular aggregate in which coarse particles are attached to coarse particles as long as the amount of fine particles connected can be reduced as much as possible.

The method for preventing the binding component from remaining on the surface of the granular aggregate or the surface of the coarse particles is not particularly limited, but it is not always easy to make it selectively exist only in the interparticle bonding portion in terms of production. Therefore, when a component having a binding ability remains on the surface of the granular aggregate or the coarse single particles, the component remaining on the surface is physically peeled off, and the exposed surface of the remaining component is altered by a chemical treatment. Alternatively, a method such as binding and covering a substance having no binding ability on the exposed surface of the component may be exercised under appropriate conditions. Alternatively, a component that loses its binding ability on the exposed surface in a relatively short period of time may be selected while maintaining the bound state in the interposition of binding between particles. As a preferred specific example, the method disclosed among the following methods for producing a quick-setting admixture for shotcrete is relatively simple and suitable for mass production.

The method for producing a powder quick-setting admixture for shotcrete according to the present invention is carried out by introducing quick-setting particles containing an arbitrary quick-setting component as a main component into a conventional mixer, a powder stirrer, or the like. While stirring, the liquid of the binding component is spray-added to the quick-setting particles. Incidentally, as the quick-setting particles, a commercially available powder quick-setting agent for shotcrete can be used as it is. The binding component does not necessarily have to be liquid at room temperature. A substance that can be dissolved in any solvent other than water at a relatively high concentration of, for example, about 10% by weight or more per unit weight of the solvent can be used as a liquid substance dissolved in the solvent. Further, the binding component having a melting point of about 300 ° C. over room temperature can be sprayed as a liquid substance by heating a spray liquid reservoir communicating with the spraying device to a temperature slightly exceeding this melting point. In this case, it is more preferable that the path from the storage tank to the spraying device and the vicinity of the spraying port are heated and kept at that temperature. The binding component having a low solubility in the solvent to be used at room temperature can be sprayed and used as a liquid obtained by appropriately heating the solvent to a temperature not higher than the boiling point of the solvent to increase the amount of dissolution.
The spraying may be performed at the stage of preparing the quick-setting particles and at the time of mixing the constituent materials of the quick-setting particles. The amount of the liquid binding component sprayed is 0.5 to 20 parts by weight with respect to 100 parts by weight of the quick-setting particles, and the spraying time is appropriately determined depending on the amount of the object to be sprayed so that the spraying can be performed substantially evenly. Well, for example, it is desirable that the treatment is performed for about 10 to 600 seconds per 1% by weight of the liquid binding component with respect to the sprayed object. The device used for spray addition is not particularly limited, but a Lodige mixer can be used as an example. After completion of spraying, mix or stir for about 1 to 5 minutes. Mixing and stirring more than this is not preferable because granulation enlargement due to particle bonding may proceed excessively. Then
1 to 100 parts by weight of the quick-setting particles that have been sprayed
20 parts by weight of the quick-setting powder, powdery water reducing agent, shirasu balloon, silica fume, activated clay mineral powder, or any one or more kinds of powder is added to the sprayed quick-setting particles,
Mix well. If the addition amount is less than 1 part by weight, it may be difficult to sufficiently cover the surface of the binding component remaining on the surface of the quick-setting particles, which is not preferable. In addition, if the amount added exceeds 20 parts by weight, the amount of added powder that is not attached to the binding component increases, which may lead to a new dust source, which is not preferable.

Here, the powdery water reducing agent is a powdery water reducing agent in addition to a normal water reducing agent, a high performance water reducing agent, an AE water reducing agent,
It may be any of the high performance AE water reducing agents. Further, the quick-setting powder, if the powder is a powder containing a quick-setting component as a main component that can impart quick-setting property to mortar or concrete, its chemical composition,
The structural state and the like are not limited, and examples thereof include a calcium aluminate-based composition, a calcium sulfaluminate-based composition, a calcium-sodium-aluminate-based composition, a calcium-fluoro-aluminate-based composition, and a calcination. There are alumite, etc., and the state thereof may be a compound, a solid solution, an amorphous body, or a mixture of two or more kinds thereof.
Further, the quick-setting powder may contain a component other than the quick-setting component in addition to the quick-setting component, for example, a quick-setting promoting component,
Further, it may be a powder having the same components as the quick-setting particles to be sprayed. The activated clay mineral powder refers to a powder in an active state in which structural water is partially or almost completely removed from a known hydrous clay mineral, and the kind of the hydrous clay mineral is not limited. As the shirasu balloon and silica fume, any known powdery one can be used. By adding and mixing such powder to the sprayed quick-setting particles, the added powder adheres to or binds to the binding component remaining on the surface of the sprayed quick-setting particles (including single particles and their granular aggregates). Since the active ingredient is impregnated and absorbed in the additive powder, the binding ingredient remaining exposed on the surface of the formed quick-setting particles is hardly seen.

The construction method using the powdered quick-setting admixture for shotcrete according to the present invention may be either a wet construction method or a dry construction method which has been conventionally carried out.
The wet method is recommended because it produces less dust. An example of the wet method is as follows: While the concrete kneaded mixture (base concrete) of known composition consisting of at least cement, aggregate and water is being pumped, the powder quick-setting agent is continuously supplied from the quick-setting agent feeder. Then, spray this with a spraying machine. As the spraying device and the quick-setting admixture supplying device, any device conventionally used for powder quick-setting admixture can be arbitrarily applied. In any of the methods, the amount of the quick-setting concrete quick-setting admixture added to the concrete mixture before hardening or the concrete mixture before addition of water is generally 5 to 15 parts by weight per 100 parts by weight of cement in the concrete. And

[0017]

EXAMPLES The present invention will be described below with reference to examples. [Materials used] (1) Cement: ordinary Portland cement (manufactured by Taiheiyo Cement Co., Ltd.) (2) Fine aggregate: crushed sand from Moji-ku, Kitakyushu City (specific gravity: 2.6)
9) 30 parts by weight and sea sand off the coast of Gonoura, Iki-gun, Nagasaki Prefecture (specific gravity;
2.59) 70 parts by weight of mixture (3) Coarse aggregate: crushed stone from Kakuro, Moji-ku, Kitakyushu City (specific gravity; 2.
80) (4) Quick setting particles: a powdered quick setting agent for commercial shotcrete (product name: Shot Master, Taiheiyo Cement Co., Ltd.)
(Production) (5) Liquid spray agent: the following A to G. However, A to D are liquid sprays at room temperature (about 20 ° C.). E to G are liquid sprays in a high temperature environment. A: diethylene glycol B: alkylene oxide adduct of lower alcohol (average molecular weight 200) C: liquid paraffin having a viscosity of about 70 mm ² / s at 40 ° C. D: methanol in which ammonium salt of naphthalene sulfonic acid is dissolved (in 100 parts by weight of methanol, naphthalene is added) Liquid in which 30 parts by weight of ammonium sulfonate is dissolved) E: Ethylene-vinyl acetate copolymer F: Ethylcellulose G: Polymethylmethacrylate (6) Powder additive: the following H to K. H: Powder same quick-setting agent as in (4) above I: Polycarboxylic acid type powdery high-performance water reducing agent (Product name: Coreflow NF-100, Taiheiyo Cement Co., Ltd.) J: Shirasu balloon powder (Product name: Sankilite) , Manufactured by Sanyo Kasei Co., Ltd. K: Silica fume with a specific surface area of 200,000 cm ² / g of brane (manufactured by SKW East Asia Co., Ltd.)

[Preparation of powder quick-setting admixture] 1000 kg of the powdered quick-setting admixture for shotcrete (4) above was used at room temperature (about 2
(5 ° C.), the liquid propellants of (A) to (G) described above are mixed with each other using a spray device manufactured by Maruyama Seisakusho Co., Ltd. Is heated to the temperature shown in Table 1 and the amount shown in Table 1 is adjusted to 10 K / min.
Metered spray addition in g. After the spraying was completed, the mixing was continued for about 3 minutes. Next, the powder additives H to K of (6) were added to the spray-treated quick-setting admixture in an amount shown in Table 1 with respect to 100 parts by weight of the quick-setting admixture, and the temperature was kept at room temperature for about 1 minute. Mixing was performed.

[0019]

[Table 1]

[Preparation of Base Concrete] (1)
~ Using the material of (3) and water, (1); 360 Kg / m
³ , (2); 983 Kg / m ³ , (3); 700 Kg / m
³ , water; the mixture was put into a commercially available twin-screw forced kneading mixer (internal volume 2.5 m ³ ) so as to have a composition of 216 kg / m ³ , and kneaded for about 45 seconds to prepare a base concrete.

[Preparation of sprayed concrete and its spraying test] T-cleats manufactured by Sugiwe Engineering Co., Ltd. were used as a quick-setting agent supply device to the above-mentioned base concrete by a wet method, and additives were mixed and adjusted. Each of the powdered quick-setting admixtures was added at room temperature so that the compounding amount shown in Table 1 (% by weight per unit weight of cement in the base concrete) was obtained. Swing Ace manufactured by Sugiue Engineering Co., Ltd. is used as a spraying device, and the concrete to which the quick-setting agent is added is sprayed in a simulated tunnel at a temperature of about 20 ° C, which is closed by a sheet and has no wind. The amount of dust was measured at a distance of 7 m in front of the spray surface. The spraying speed and the spraying time for one time were 10 m ³ / hour × 10 minutes. Table 1 shows the amount of dust measured using a dust densitometer.

Further, by using the same quick-setting agent supply device and operating at a cylinder rotation speed of 60 Hz, the maximum pressure-feeding amount of each surface-treated powder quick-setting agent is measured to obtain each powder. The pumpability of the quick-setting admixture was evaluated. The results are also shown in Table 1. The quick-setting property of the shotcrete was examined by touching the state of about 1 minute after the spraying, and it was in a state that it could not be crushed in any of the Examples and Comparative Examples, and the good quick-set property was obtained. It was confirmed that was obtained.

[0023]

EFFECTS OF THE INVENTION The powder quick-setting admixture for shotcrete according to the present invention has a remarkably small amount of floating dust generated from the quick-setting admixture powder at the time of concrete spraying, and the quick-setting in the quick-setting admixture supply device. A desired quick-setting property can be imparted to the shotcrete without affecting the pumpability of the agent. Further, such a powdered quick-setting admixture for shotcrete can be easily produced without using special equipment or complicated process operations.

Claims (4)

[Claims] 1. A powdered quick-setting admixture for spraying concrete, wherein the quick-setting particles contain a granular aggregate formed by bonding through a binding component, and the binding property is provided on the surface of the granular aggregate. A powder quick-setting admixture for shotcrete characterized by having virtually no components. 2. The powder quick-setting admixture for shotcrete according to claim 1, which contains quick-setting single particles which do not form a granular aggregate and have substantially no binding component on the surface. 3. A quick-setting powder, a powdery water reducing agent, a shirasu balloon, after spray-adding a liquid binding component to quick-setting particles.
One or two of silica fume and activated clay mineral powder
A method for producing a powder quick-setting admixture for shotcrete, which comprises adding and mixing one or more kinds. 4. A quick-setting powder according to claim 3, a powdery water reducing agent,
The addition amount of any one or more of shirasu balloon, silica fume and activated clay mineral powder is 100
A method for producing a powdered quick-setting admixture for sprayed concrete, which is 1 to 20 parts by weight with respect to parts by weight.