Spraying method

Abstract

To provide a spraying method that suppresses the occurrence of laitance.SOLUTION: A spraying method comprises spraying, onto a target surface, a mixture formed by blending a clay mineral that contains 30 mass% or more and 100 mass% or less of smectite in the dry state and has a moisture content of 0 mass% or more and 10 mass% or less with a hydraulic composition that contains water, a hydraulic powder, and an aggregate.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a spraying method and a method for suppressing norovirus generation in a sprayable hydraulic composition.

Background Art

[0002] In order to prevent the collapse of exposed natural ground such as tunnel excavation, a spraying method using quick-setting concrete or quick-setting mortar in which a quick-setting agent is blended with concrete has been carried out. In this method, spray concrete is usually prepared at a weighing and mixing plant for cement, aggregate, and water installed at the excavation work site, and then transported by an agitator truck to a spraying machine. Then, the spray concrete and the quick-setting agent are joined and mixed by a line that pneumatically transports the spray concrete to the discharge port by a pump of the spraying machine and a line that pneumatically transports the quick-setting agent from the other side by a joining pipe provided in the middle, and sprayed onto the natural ground surface as quick-setting spray concrete until a predetermined thickness is reached.

[0003] Patent Document 1 discloses a cement concrete containing a hydrous clay mineral and calcium aluminates and a spraying material containing the cement concrete and a quick-setting agent. Further, Patent Document 2 discloses a powdery dust reducing agent containing a predetermined amount of talc, bentonite, cellulose ether, dew tangerine gum, polyacrylamide, and a predetermined defoaming agent, and spray concrete to which the powdery dust reducing agent is added. Patent Document 3 discloses a sprayable hydraulic composition containing (A) a clay mineral having a swelling degree of 15 mL / 2 g or more and 50 mL / 2 g or less, (B) one or more quick-setting agents selected from a cement mineral-based quick-setting agent and an aluminum-based quick-setting agent, cement, water, and aggregate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] Sprayed hydraulic compositions are sprayed onto the ground or the like with strong pressure, so there is a risk of generating noro due to high-pressure shock. Noro refers to the powder separated from hydraulic compositions such as mortar, water, that is, the paste component, and often contains a large amount of water. When noro is generated, the water volume increases locally, and if concrete or the like with low strength is produced, it may cause peeling of the concrete or the like and inability to withstand the deformation of the ground. The present invention provides a spraying method for suppressing the generation of noro and a method for suppressing the generation of noro in a sprayed hydraulic composition. [Means for Solving the Problems]

[0006] The present invention relates to a spraying method in which a mixture obtained by mixing a clay mineral containing 30% by mass or more and 100% by mass or less of smectite and having a water content of 0% by mass or more and 10% by mass or less at the time of drying [hereinafter referred to as component (A)] into a hydraulic composition containing water, hydraulic powder, and aggregate is sprayed onto a target surface.

[0007] The present invention also relates to a method for suppressing the generation of noro in a sprayed hydraulic composition, in which component (A) is mixed into a hydraulic composition containing water, hydraulic powder, and aggregate, and the obtained sprayed hydraulic composition is sprayed onto a target surface. [Effects of the Invention]

[0008] According to the present invention, a spraying method for suppressing the generation of noro and a method for suppressing the generation of noro in a sprayed hydraulic composition are provided. [Modes for Carrying Out the Invention]

[0009] The present invention relates to a spraying method for spraying a hydraulic composition for spraying on a target surface, and in particular to a spraying method using a cement composition for spraying quick-setting concrete or quick-setting mortar on a slope formed by tunnels such as roads, railways, and water conduits, or by natural ground excavation or embankment. The hydraulic composition for spraying in the present invention is a general term for cement mortar and cement concrete.

[0010] The mechanism by which the spraying method of the present invention suppresses the generation of slag is not clear, but is presumed to be as follows. The clay mineral mixed in the hydraulic composition contains smectite at a predetermined ratio, which promotes hetero-aggregation with the hydraulic powder, and even after the aggregate structure is destroyed by the spraying discharge pressure, the recovery speed of the aggregate structure is promoted, and the slag components are fixed before they are separated from the mortar components. In addition, by using a clay mineral having a predetermined moisture content, the water absorption rate of smectite increases, and the fixation of slag can be accelerated. It is presumed that this can suppress the generation of slag when the spray hydraulic composition is sprayed onto a target surface. The spraying method and the method for suppressing the generation of slag from the spray hydraulic composition of the present invention are not limited to the above-mentioned mechanism of action.

[0011] In the spraying method of the present invention, a mixture of (A) a clay mineral containing 30% to 100% by mass of smectite when dried and having a moisture content of 0% to 10% by mass [component (A)] mixed with a hydraulic composition containing water, hydraulic powder, and aggregate [hereinafter referred to as the spray hydraulic composition of the present invention] is sprayed onto a target surface. First, the hydraulic composition for spraying of the present invention will be described in detail.

[0012] <Hydraulic composition for spraying> The hydraulic composition for spraying of the present invention contains hydraulic powder, aggregate, (A) a clay mineral [component (A)] containing 30% by mass or more and 100% by mass or less of smectite when dry and having a moisture content of 0% by mass or more and 10% by mass or less, and water.

[0013] <Hydraulic powder> The hydraulic powder used in the sprayable hydraulic composition of the present invention is a powder that hardens by mixing with water. Examples include ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement, sulfate-resistant Portland cement, low-heat Portland cement, medium-heat Portland cement, white Portland cement, alumina cement, and eco-cement (e.g., JIS R 5214, etc.). Among these, from the perspective of the spread of the sprayable hydraulic composition, cement selected from early-strength Portland cement, ordinary Portland cement, sulfate-resistant Portland cement, and white Portland cement is preferred, and early-strength Portland cement and ordinary Portland cement are more preferred.

[0014] In addition, the hydraulic powder may contain blast furnace slag, fly ash, silica fume, anhydrous gypsum, etc., and may also contain non-hydraulic fine limestone powder, etc. As the hydraulic powder, blast furnace cement, fly ash cement, or silica fume cement in which cement is mixed with blast furnace slag, fly ash, silica fume, etc. may be used.

[0015] <Aggregate> The sprayable hydraulic composition of the present invention contains aggregate. Examples of the aggregate include aggregates selected from fine aggregate and coarse aggregate. Examples of the fine aggregate include those defined by No. 2311 in JIS A 0203-2014. Examples of the fine aggregate include river sand, land sand, mountain sand, sea sand, lime sand, silica sand, and crushed sand thereof, blast furnace slag fine aggregate, ferronickel slag fine aggregate, lightweight fine aggregate (artificial and natural), and recycled fine aggregate, etc. Examples of the coarse aggregate include those defined by No. 2312 in JIS A 0203-2014. For example, the coarse aggregate includes river gravel, land gravel, mountain gravel, sea gravel, lime gravel, crushed stone thereof, blast furnace slag coarse aggregate, ferronickel slag coarse aggregate, lightweight coarse aggregate (artificial and natural), and recycled coarse aggregate, etc. The fine aggregate and the coarse aggregate may be used by mixing those of different types, or a single type may be used. The sprayable hydraulic composition of the present invention can contain fine aggregate as an aggregate. The amount of the fine aggregate used in the sprayable hydraulic composition of the present invention is preferably 500 kg / m 3 or more, more preferably 600 kg / m 3 or more, and preferably 2000 kg / m 3 or less, more preferably 1700 kg / m 3 or less. In the sprayable hydraulic composition of the present invention, the fine aggregate ratio is preferably 35% or more, more preferably 45% or more, and preferably 100% or less, more preferably 70% or less, still more preferably 65% or less. Here, the fine aggregate ratio is the volume content ratio of the fine aggregate in all aggregates.

[0016] In the sprayable hydraulic composition of the present invention, the water / hydraulic powder ratio (W / C) is preferably 30% by mass or more, more preferably 35% by mass or more, still more preferably 40% by mass or more, from the viewpoint of norovirus suppression, and preferably 80% by mass or less, more preferably 70% by mass or less, still more preferably 65% by mass or less. That is, in the sprayable hydraulic composition of the present invention, from the viewpoint of norovirus suppression, water is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, still more preferably 40 parts by mass or more, and preferably 80 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 65 parts by mass or less, with respect to 100 parts by mass of the hydraulic powder. Note that this water / hydraulic powder ratio (W / C) represents the ratio of water to the hydraulic powder in the sprayable hydraulic composition as a mass percentage (mass%), and is calculated by (water / hydraulic powder) × 100. In addition, when the hydraulic powder contains, in addition to a powder having physical properties that harden by a hydration reaction such as cement, a powder having a pozzolanic action, a powder having latent hydraulicity, and a stone powder (calcium carbonate powder), in the present invention, the amounts thereof are also included in the amount of the hydraulic powder. Further, when the powder having physical properties that harden by a hydration reaction contains a high-strength admixture, the amount of the high-strength admixture is also included in the amount of the hydraulic powder. However, when these components are included in the quick-setting agent described in detail later, the components included in the quick-setting agent are not included in the amount of the hydraulic powder. This is the same for other parts by mass related to the mass of the hydraulic powder, etc.

[0017] <Component (A)> (A) component is a clay mineral containing 30% by mass or more and 100% by mass or less of smectite when dried, and having a water content of 0% by mass or more and 10% by mass or less.

[0018] (A) component's smectite content when dried is 30% by mass or more, preferably 35% by mass or more, more preferably 38% by mass or more, still more preferably 40% by mass or more, from the viewpoint of norovirus suppression, and 100% by mass or less, preferably 80% by mass or less, more preferably 60% by mass or less, from the viewpoint of norovirus suppression. (A) component's smectite content when dried is the smectite content calculated based on the following methylene blue adsorption amount in the (A) component dried at 105°C for 1 hour in a hot air dryer.

[0019] <Method for measuring the smectite content of component (A)> (1) Measurement of methylene blue adsorption amount (A) component's methylene blue adsorption amount is measured by the following method in accordance with Japanese Industrial Standard (JIS Z 2451:2019). <Reagents> 10 mmol / L aqueous solution of methylene blue (molecular weight 374) Sodium pyrophosphate (Na 4 P 2 O 7 ) 0.2% by mass aqueous solution <Operating method> Put about 0.4 g of component (A) into a 100 mL screw tube, and add 40 g of a 0.2 mass% aqueous solution of sodium pyrophosphate thereto. After dispersing this mixture with an ultrasonic cleaner (ASUCLEANER, ASU-3, AS ONE Corporation) for 30 minutes, it was heated with warm water at 80 °C for 30 minutes. While stirring the dispersed mixture with a magnetic stirrer, a 10 mmol / L aqueous methylene blue solution was added dropwise. Each time a predetermined amount was added dropwise, a part of the mixture was sucked up from the supernatant using a glass Pasteur pipette and dropped onto filter paper. The supernatant was dropped so that a spot with a diameter of about 10 mm was formed on the filter paper. This operation was repeated until a halo was confirmed around the spot. When a halo was confirmed, the end point of the titration was taken when the width of the halo exceeded 2 mm. The calculation of the methylene blue adsorption amount (mmol) is to convert the product of the titration amount (L) and the methylene blue aqueous solution concentration (10 mmol / L) per 100 g of component (A). (2) Calculation of smectite content The calculation of the smectite content is carried out with reference to "A proposed method for the determination of small amounts of smectites in clay mineral mixtures, Proceedings of British Ceramics Society 28 137-145, 1979" and "Evaluation of the montmorillonite content of bentonite considering the measurement accuracy of the methylene blue adsorption test, Journal of the Japanese Geotechnical Society C (Geomechanics), Vol. 76, No. 1, 26-39, 2020". Specifically, 140 mmol / 100 g is adopted as the saturated methylene blue adsorption amount of smectite. From the methylene blue adsorption amounts of various clay minerals measured, the saturated adsorption amount is subtracted and then multiplied by 100 to calculate the smectite content of various clay minerals.

[0020] The water content of component (A) is 0% by mass or more, preferably 1% by mass or more, more preferably 2% by mass or more, and from the perspective of norovirus inhibition, 10% by mass or less, preferably 9% by mass or less, more preferably 8.5% by mass or less, still more preferably 8% by mass or less. The water content of component (A) is calculated based on the mass reduction of component (A) before and after drying at 105°C for 1 hour using a warm air dryer, and the mass of component (A) before drying, by measuring approximately 2 g of component (A) into an aluminum cup.

[0021] Examples of the clay mineral of component (A) include cation exchangeable layered silicates. Examples of such clay minerals include one or more clay minerals selected from smectite and bentonite. Smectite is a group of cation exchangeable layered silicates belonging to clay minerals. As natural products, in addition to montmorillonite, which is well-known as the main component of bentonite, beidellite, hectorite, saponite, nontronite, etc. can be mentioned, and as synthetic products, swelling fluorine mica etc. can be mentioned. Among these, as component (A), from the perspective of norovirus inhibition, clay minerals selected from bentonite, saponite, hectorite, and montmorillonite are preferred, clay minerals selected from bentonite and montmorillonite are more preferred, and bentonite is still more preferred. The content of the clay mineral selected from bentonite, saponite, hectorite, and montmorillonite is preferably 60% by mass or more, more preferably 100% by mass, and still more preferably 100% by mass of bentonite content, among the clay minerals contained in the sprayable hydraulic composition.

[0022] From the perspective of norovirus inhibition, the clay mineral of component (A) is preferably a clay mineral with a swelling degree of 10 mL / 2 g or more and 50 mL / 2 g or less. From the perspective of norovirus inhibition, the swelling degree of the clay mineral of component (A) is preferably 10 mL / 2 g or more, more preferably 15 mL / 2 g or more, still more preferably 20 mL / 2 g or more, and preferably 50 mL / 2 g or less, more preferably 45 mL / 2 g or less, still more preferably 40 mL / 2 g or less. When the (A) component contains a plurality of types of clay minerals, this swelling degree is the swelling degree in a mixture of the plurality of types of (A) components.

[0023] This swelling degree is measured according to the swelling test method for bentonite (powdered) of the Japan Bentonite Industry Association JBAS104:77. That is, 2.0 g of a sample adjusted to 8.0% by mass of moisture is added to a 100 mL stoppered graduated cylinder containing 100 mL of distilled water in about 10 portions. At this time, the next addition is made after the previous additive has deposited on the bottom of the graduated cylinder. When left for 24 hours, the apparent volume of the sample mass at the bottom of the graduated cylinder that has swelled is read from the scale of the graduated cylinder and expressed as the swelling degree (mL / 2 g).

[0024] From the viewpoint of norovirus inhibition, the average particle diameter of the clay mineral of the (A) component is preferably 0.5 μm or more, more preferably 2 μm or more, still more preferably 5 μm or more, and from the viewpoint of norovirus inhibition, preferably 100 μm or less, more preferably 80 μm or less, still more preferably 60 μm or less. The average particle diameter of the clay mineral of the (A) component is a value measured in an ethanol solvent with a laser diffraction / scattering type particle size distribution measuring device (LA-920).

[0025] From the viewpoint of norovirus inhibition, the spraying hydraulic composition of the present invention contains the (A) component in an amount of preferably 0.03% by mass or more, more preferably 0.04% by mass or more, still more preferably 0.05% by mass or more, and preferably 7% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, based on the hydraulic powder in the spraying hydraulic composition.

[0026] <Water> The spraying hydraulic composition of the present invention contains water. Examples of the water include tap water, groundwater, lake water, and river water.

[0027] <Quick-setting agent> The sprayable hydraulic composition of the present invention can optionally contain a quick-setting agent. The quick-setting agent can be used in any form, such as powdery, liquid, or a combination thereof. Examples of the quick-setting agent include one or more quick-setting agents selected from cement mineral-based quick-setting agents and aluminum-based quick-setting agents.

[0028] Examples of the cement mineral-based quick-setting agent include one or more selected from calcium aluminate, calcium sulfoaluminate, and calcium aluminate. Examples of the aluminum-based quick-setting agent include one or more selected from aluminum salts containing aluminum hydroxide, sodium aluminate, potassium aluminate, aluminum sulfate, aluminum chloride, potassium aluminum sulfate, potassium alum, iron alum, and ammonium iron alum. From the viewpoint of strength development, the quick-setting agent is preferably one or more selected from calcium aluminate, calcium sulfoaluminate, calcium aluminate, aluminum sulfate, sodium aluminate, and aluminum sulfate; more preferably one or more selected from calcium aluminate, calcium sulfoaluminate, and aluminum sulfate; and still more preferably one or more selected from calcium aluminate and aluminum sulfate. The quick-setting agent may contain gypsum, alkali carbonates such as sodium carbonate, potassium carbonate, and sodium hydrogen carbonate, sodium sulfate, and calcium hydroxide.

[0029] As setting agents, those such as Denka's Denka Natomic series, Denka Natomic US-32, Denka Natomic US-50, Denka Natomic TYPE-5, Denka Natomic TYPE-10, Denka Natomic Z, Natomic L, Natomic LSA, Natomic USS, Natomic HSS, Denka Σ Shot V, Pacific Material Co., Ltd.'s Pacific Shot Master series, Pacific Shot Master A, Pacific Shot Master A (for high strength), Pacific Shot Master H, Pozolith Solutions Co., Ltd.'s Master Rock series, Master Rock SA161, Master Rock SA167, Master Rock SA178, Master Rock SA143, Master Rock SA446, Seek Japan Co., Ltd.'s Signit series, Signit P10AF, Signit L53AF, Signit U, etc. can be used.

[0030] <Calcium aluminate> Calcium aluminate (hereinafter referred to as CA compounds) is a general term for compounds mainly composed of CaO and Al 2 O 3 and having hydration activity. A part of CaO and / or Al 2 O 3 is replaced by alkali metal oxides, alkaline earth metal oxides, silicon oxide, titanium oxide, iron oxide, alkali metal halides, alkaline earth metal halides, alkali metal sulfates, and alkaline earth metal sulfates, etc., or a compound in which these are slightly dissolved in a substance mainly composed of CaO and Al 2 O 3 3 . CA compounds may be either crystalline or amorphous.

[0031] Specific examples of crystalline CA compounds include, when CaO is C and Al 2 O 3 is A, C3A and C14A5 in which an alkali metal is dissolved therein, CA, C12A7, C11A7·CaF 2 , C4A·Fe 2 O 3 , and C3A3·CaSO 4 etc. can be mentioned. Also, for example, Na 2 O, K2 O, Li 2 It may contain O. Since the quick-setting property is good, amorphous calcium aluminate is preferred.

[0032] Note that the calcium aluminate used in this embodiment may be contaminated with trace amounts of alkali metals and / or alkaline earth metals from industrial raw materials, and there is a possibility that CAs containing these alkali metals and / or alkaline earth metals are partially generated. However, the presence of these small amounts of alkali metals and / or alkaline earth metals does not impose any restrictions.

[0033] CaO / Al of calcium aluminate 2 O 3 The molar ratio is not particularly limited. However, considering the early strength development, the molar ratio is preferably 2.0 or more and 3.0 or less, and more preferably 2.2 or more and 2.8 or less. When the molar ratio is 2.0 or more, the initial setting property can be improved. When it is 3.0 or less, good long-term strength development is easily obtained.

[0034] The Blaine specific surface area of calcium aluminate (hereinafter sometimes simply referred to as "Blaine") is 4,000 cm 2 / g or more and 8,000 cm 2 / g or less, preferably 5,000 cm 2 / g or more and 7,000 cm 2 / g or less. When the specific surface area is 4,000 cm 2 / g or more and 8,000 cm 2 / g or less, early strength development is easily obtained, and the workability of mortar and / or concrete during spraying can be improved.

[0035] <Gypsum> Gypsum is effective in promoting the loss of fluidity immediately after the preparation of cement mortar or cement concrete and in promoting the strength development within about one day. Although there is no particular limitation on the gypsum, for example, any gypsum such as potassium gypsum, chromium gypsum, iron gypsum, ammonium gypsum, sodium gypsum, natural gypsum, etc. can be used alone or in combination. In particular, as the one that causes the loss of fluidity of cement mortar or cement concrete, it is preferable to contain at least one selected from the group consisting of potassium gypsum, sodium gypsum, and ammonium gypsum.

[0036] <Cement> As the cement, any of anhydrous, hemihydrate, and dihydrate cements can be used. Among these, anhydrous gypsum is preferable from the viewpoint of good strength development. The particle size of the cement, from the viewpoint of initial strength development, is preferably 2,000 cm 2 / g or more in terms of Blaine specific surface area, and more preferably 3,000 cm 2 / g or more and 6,000 cm 2 / g or less. The Blaine specific surface area value in this specification can be determined in accordance with JIS R 5201 (Physical test methods for cement).

[0037] <Calcium hydroxide> Calcium hydroxide is an effective material for ensuring extremely initial fluidity reduction and long-term strength development. Although there is no particular limitation on the calcium hydroxide, it includes slaked lime generated when quicklime hydrates and carbide slag generated when carbide hydrates. Also, commercially available calcium hydroxide can be used, and any of the above combinations is also possible.

[0038] The Blaine specific surface area of calcium hydroxide is preferably 5,000 cm 2 / g or more and 15,000 cm 2 / g or less, and more preferably 7,000 cm 2 / g or more and 13,000 cm 2 / g or less. When the specific surface area is 5,000 cm2 15,000 cm / g or more 2 By being 15,000 cm / g or less, the quick-setting property and the long-term strength development property can be ensured, and it becomes easy to obtain good initial strength development property.

[0039] <Alkali carbonate> Alkali carbonate refers to alkali metal carbonate salts and can significantly improve the setting property and initial strength development property of powdered quick-setting agents. Although not particularly limited as the alkali carbonate, for example, lithium carbonate, sodium carbonate, sodium sesquicarbonate, potassium carbonate, sodium bicarbonate, sodium hydrogen carbonate, etc. can be mentioned. Particularly effective ones for setting and initial strength development are sodium carbonate, potassium carbonate, sodium sesquicarbonate, sodium bicarbonate, and sodium hydrogen carbonate, and it is also possible to combine one or more of these. Preferably, it is at least one selected from the group consisting of sodium carbonate, sodium sesquicarbonate, sodium bicarbonate, and potassium carbonate.

[0040] In the spraying hydraulic composition of the present invention, an additive for the spraying hydraulic composition (hereinafter referred to as the additive of the present invention), which is a mixture of the above component (A) and a quick-setting agent, may be used. The additive is, for example, mixed with a hydraulic composition containing hydraulic powder and water when spraying the spraying hydraulic composition. The additive of the present invention preferably contains 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and preferably 98% by mass or less, more preferably 96% by mass or less, still more preferably 95% by mass or less of the quick-setting agent from the viewpoints of norovirus suppression and strength development property.

[0041] In the additive of the present invention, the mass ratio [(quick-setting agent) / (A)] of the content of component (A) to the content of the quick-setting agent is preferably 0.5 or more, more preferably 0.7 or more, still more preferably 1.0 or more, and preferably 90 or less, more preferably 70 or less, still more preferably 50 or less, even more preferably 40 or less, even more preferably 30 or less, even more preferably 20 or less from the viewpoints of norovirus suppression and strength development property.

[0042] When the sprayable hydraulic composition of the present invention contains a quick-setting agent, the quick-setting agent is preferably 4 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 6 parts by mass or more, even more preferably 7 parts by mass or more, and preferably 20 parts by mass or less, more preferably 18 parts by mass or less, still more preferably 15 parts by mass or less, from the viewpoint of norovirus suppression, based on 100 parts by mass of the hydraulic powder contained in the sprayable hydraulic composition.

[0043] <Dispersant> The sprayable hydraulic composition of the present invention can optionally contain a dispersant. From the viewpoint of discharge workability, a polycarboxylic acid-based dispersant is preferred.

[0044] Examples of the polycarboxylic acid-based dispersant include copolymers of polyalkylene glycol and monoester of (meth)acrylic acid and carboxylic acid such as (meth)acrylic acid (e.g., compounds described in JP-A-8-12397), copolymers of unsaturated alcohol having polyalkylene glycol and carboxylic acid such as (meth)acrylic acid, copolymers of unsaturated alcohol having polyalkylene glycol and dicarboxylic acid such as maleic acid, etc. Here, (meth)acrylic acid means a carboxylic acid selected from acrylic acid and methacrylic acid.

[0045] When the sprayable hydraulic composition of the present invention contains a dispersant, the dispersant is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, still more preferably 0.07 part by mass or more, and preferably 1 part by mass or less, more preferably 0.5 part by mass or less, still more preferably 0.3 part by mass or less, from the viewpoints of discharge workability and norovirus suppression, based on 100 parts by mass of the hydraulic powder contained in the sprayable hydraulic composition.

[0046] The sprayable hydraulic composition of the present invention may optionally contain one or more of a high-performance water-reducing agent, a high-performance air-entraining water-reducing agent, an air-entraining water-reducing agent, a water-reducing agent containing a fluidizing agent, an expansion agent, a hardening accelerator, a hardening retarder, a polymer for cement, a foaming agent, a waterproof agent, a rust preventive agent, a shrinkage reducing agent, a pigment, a fiber, a water repellent, a white efflorescence preventive agent, a thickening agent, etc.

[0047] The target surfaces to which the sprayable hydraulic composition of the present invention is sprayed include tunnels such as roads, railways, and water conduits, slopes formed by in-situ excavation, embankment, etc., underground spaces, and concrete structures to be repaired by the spraying method.

[0048] <Spraying method> The spraying method of the present invention is a spraying method in which the mixture (hereinafter referred to as the sprayable hydraulic composition of the present invention) obtained by mixing the component (A) with a hydraulic composition containing water, hydraulic powder, and aggregate is sprayed onto the target surface. Also, the spraying method of the present invention may be a spraying method in which the sprayable hydraulic composition of the present invention is sprayed onto the target surface in an environment with a humidity of 80% RH or more. Also, the spraying method of the present invention may be a spraying method in which the sprayable hydraulic composition of the present invention is sprayed onto the target surface. In the spraying method of the present invention, a quick-setting agent may be mixed with the above-mentioned sprayable hydraulic composition, and the sprayable hydraulic composition mixed with the quick-setting agent may be sprayed onto the target surface. The spraying method of the present invention can apply the modes described in the sprayable hydraulic composition of the present invention. The preferred modes of the component (A), the hydraulic powder, the aggregate, the water, the quick-setting agent, and the dispersant in the spraying method of the present invention are the same as the preferred modes described in the sprayable hydraulic composition of the present invention. Also, the preferred content of each component in the sprayable hydraulic composition of the present invention can be applied to the spraying method of the present invention by replacing it with the preferred mixing amount of each component.

[0049] The spraying method of the present invention preferably includes a method in which the sprayable hydraulic composition of the present invention and the quick-setting agent are separately pressure-fed and then joined and mixed, or a method in which the quick-setting agent slurry obtained by adding water to the powdered quick-setting agent to form a slurry before joining and mixing is joined and mixed with the sprayable hydraulic composition and then sprayed, and a wet spraying method is preferred. Examples of the wet spraying method include a method in which a hydraulic powder, an aggregate, and water are mixed and kneaded, then pressure-fed by air, and the component (A) and the quick-setting agent are joined and mixed and sprayed. The spraying method of the present invention preferably involves spraying a sprayable hydraulic composition, which is obtained by separately pressure-feeding by air and mixing a clay mineral as the component (A), water, a hydraulic composition containing a hydraulic powder and an aggregate, onto a target surface. After manufacturing the hydraulic composition by mixing water, the hydraulic powder, and the aggregate, the component (A) may be mixed with the hydraulic composition using a mixer, or the component (A) and the hydraulic composition may be separately pressure-fed and then joined and mixed. From the perspective of norovirus suppression, it is preferable to separately pressure-feed the component (A) and the hydraulic composition and then join and mix them.

[0050] In the spraying method of the present invention, when the sprayable hydraulic composition of the present invention is pressure-fed by air and sprayed onto a target surface, the pressure of the air for spraying the sprayable hydraulic composition onto the target surface is preferably 0.2 MPa or more, more preferably 0.3 MPa or more, still more preferably 0.4 MPa or more, and from the perspective of norovirus suppression, preferably 1.2 MPa or less, more preferably 1.0 MPa or less, still more preferably 0.8 MPa or less, and even more preferably 0.6 MPa or less. It is preferable that the pressure for pressure-feeding the sprayable hydraulic composition of the present invention by air is within the above range.

[0051] In the spraying method of the present invention, when the sprayable hydraulic composition of the present invention is pressure-fed by air and sprayed onto a target surface, the volume ratio a / b of the air flow rate a for spraying the sprayable hydraulic composition onto the target surface to the flow rate b of the hydraulic composition before being sprayed onto the target surface is preferably 10 or more, more preferably 20 or more, still more preferably 30 or more, and from the perspective of norovirus suppression, preferably 150 or less, more preferably 120 or less, still more preferably 100 or less.

[0052] The air flow rate a is determined from the compressor discharge air volume specification (measured in accordance with JIS B 8341). When the compressor discharge air volume specification is unknown, the air flow rate a may be measured using an air flow meter attached to the compressor. In addition, the flow rate b of the hydraulic composition is calculated by dividing the volume of the discharged hydraulic composition by the time required from the start of discharge to the end of discharge when a predetermined hydraulic composition is discharged.

[0053] In the spraying method of the present invention, when the sprayable hydraulic composition of the present invention is pneumatically conveyed and sprayed onto the target surface, the ratio L / d of the distance L from the mixing part of the component (A) and the hydraulic composition to the discharge port for discharging the mixture to the inner diameter d of the discharge port is preferably 1 or more, more preferably 2 or more, still more preferably 5 or more, from the viewpoints of norovirus suppression and discharge workability, and preferably 500 or less, more preferably 200 or less, still more preferably 110 or less, from the viewpoints of norovirus suppression and discharge workability. The mixing part of the component (A) and the hydraulic composition that is the basis of the distance L is the mixing part closest to the discharge port.

[0054] In the spraying method of the present invention, from the viewpoint of more strongly feeling the effects of the present invention, the sprayable hydraulic composition of the present invention is preferably sprayed onto the target surface in an environment with a humidity of 80% RH or more, more preferably 85% RH or more, still more preferably 90% RH or more, and preferably 100% RH or less. In the environment with a humidity of 80% RH or more described above, the component (A) absorbs moisture and the water content of the component (A) increases. However, in the spraying method of the present invention, even in such an environment, by using the component (A) with a predetermined water content, the generation of norovirus can be suppressed.

[0055] The spraying method of the present invention will be described in detail with specific examples. Note that the spraying method of the present invention is not limited to this specific example. In the spraying method of the present invention, first, a hydraulic powder, an aggregate, and water are mixed to produce a hydraulic composition. The hydraulic composition produced by mixing a hydraulic powder, an aggregate, and water, and further the hydraulic composition for spraying of the present invention, have a water / hydraulic powder ratio (W / C) [mass percentage (mass%) of water and hydraulic powder in the hydraulic composition] of, from the viewpoint of norovirus suppression, preferably 30% by mass or more, more preferably 35% by mass or more, still more preferably 40% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, still more preferably 65% by mass or less.

[0056] In the present invention, the mixing of the hydraulic powder, the aggregate, water, and other optional components can be carried out by known methods. For example, a method of simultaneously mixing the hydraulic powder, water, and aggregate can be mentioned. For the mixing of these components, mixing mixers such as a pan-type forced mixer, a twin-shaft forced mixer, and a tilting mixer can be used.

[0057] In the present invention, a hydraulic composition obtained by mixing a hydraulic powder, an aggregate, and water can be mixed with component (A) and optionally a quick-setting agent to produce a hydraulic composition for spraying. The mixing of the hydraulic composition with component (A) and / or the quick-setting agent can be carried out, for example, by a general spraying method in which the hydraulic composition, component (A), and / or the quick-setting agent are pneumatically transported and mixed by confluence.

[0058] In the present invention, component (A) is preferably mixed in an amount of 0.03 part by mass or more, more preferably 0.04 part by mass or more, still more preferably 0.05 part by mass or more, and preferably 7 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 3 parts by mass or less, per 100 parts by mass of the hydraulic powder in the hydraulic composition for spraying, from the viewpoint of norovirus suppression.

[0059] In the present invention, when using the quick-setting agent, from the viewpoints of norovirus suppression and strength development, the quick-setting agent is preferably mixed in an amount of 4 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 6 parts by mass or more, even more preferably 7 parts by mass or more, and preferably 20 parts by mass or less, more preferably 18 parts by mass or less, still more preferably 15 parts by mass or less, based on 100 parts by mass of the hydraulic powder in the hydraulic composition.

[0060] Further, in the spraying method of the present invention, the dispersant can be optionally used. When using the dispersant in the spraying method of the present invention, the dispersant can be premixed with water and used in the step of preparing the hydraulic composition. In the present invention, when using the dispersant, from the viewpoints of spraying workability and norovirus suppression, the dispersant is preferably mixed in an amount of 0.01 part by mass or more, more preferably 0.05 part by mass or more, still more preferably 0.07 part by mass or more, and preferably 1 part by mass or less, more preferably 0.5 part by mass or less, still more preferably 0.3 part by mass or less, based on 100 parts by mass of the hydraulic powder in the hydraulic composition.

[0061] In the spraying method of the present invention, the sprayed hydraulic composition thus prepared is sprayed onto the object. The spraying method of the present invention can be carried out by conventional spraying equipment. The spraying equipment only needs to be able to perform spraying smoothly. For example, for the pressure feeding of the hydraulic composition, "Ariba 280" manufactured by Ariba Co., Ltd. etc. can be used, and for the pressure feeding of the component (A) and / or the quick-setting agent, "Natomcrete" manufactured by Chiyoda Manufacturing Co., Ltd. etc. can be used, and it is possible to mix both to prepare a sprayed hydraulic composition and perform spraying.

[0062] <Method for suppressing norovirus generation in sprayed hydraulic composition> The present invention provides a method for suppressing norovirus generation in a sprayed hydraulic composition, which comprises mixing a clay mineral [(component (A))] containing 30% by mass or more and 100% by mass or less of smectite and having a water content of 0% by mass or more and 10% by mass or less when dried into a hydraulic composition containing water, a hydraulic powder, and an aggregate, and spraying the obtained sprayed hydraulic composition onto the target surface. In the method for suppressing norovirus generation in the sprayed hydraulic composition of the present invention, the preferred embodiments of the hydraulic powder, aggregate, component (A), and water are the same as those described in the sprayed hydraulic composition of the present invention. Further, in the method for suppressing norovirus generation in the sprayed hydraulic composition of the present invention, optional components such as the quick-setting agent described in the sprayed hydraulic composition of the present invention can be used in the sprayed hydraulic composition, and the preferred embodiments of these optional components are also the same as those described in the sprayed hydraulic composition of the present invention. A preferred embodiment of the method for suppressing norovirus generation in the sprayed hydraulic composition of the present invention is the same as the preferred embodiment of the spraying method of the present invention, and by this method, the generation of norovirus in the sprayed hydraulic composition sprayed on the target surface can be suppressed. In particular, according to the method for suppressing norovirus generation in the sprayed hydraulic composition of the present invention, the generation of norovirus in the sprayed hydraulic composition sprayed on the target surface in an environment with a humidity of 80% RH or more can be suppressed.

[0063] In the method for suppressing norovirus generation in the sprayed hydraulic composition of the present invention, from the viewpoint of more experiencing the effects of the present invention, the sprayed hydraulic composition of the present invention is preferably sprayed on the target surface in an environment with a humidity of 80% RH or more, more preferably 85% RH or more, still more preferably 90% RH or more, and preferably 100% RH or less. In the above environment with a humidity of 80% RH or more, component (A) will absorb moisture and the moisture content of component (A) will increase. However, in the spraying method of the present invention, even in such an environment, by using component (A) with a predetermined moisture content, the generation of norovirus can be suppressed.

Examples

[0064] In the examples and comparative examples, a hydraulic composition was produced with the formulations shown in Table 1, and the (A) component shown in Table 2 or the (A) component and the quick-setting agent shown in Table 3 were mixed into this hydraulic composition to produce a sprayed hydraulic composition. Then, the norovirus generation rate of the sprayed hydraulic composition was evaluated. Also, a sprayed hydraulic composition was produced with the formulations shown in Table 4, and the norovirus generation rate of the sprayed hydraulic composition was evaluated.

[0065]

Table 1

[0066] (1) Ingredients The ingredients in Table 1 are as follows. W: Tap water C: Ordinary Portland cement (two-component mixture: Pacific Cement / Sumitomo Osaka Cement = 1 / 1, mass ratio), density 3.16 g / cm 3 S: Fine aggregate (S): Sand from Chengyang, density 2.55 g / cm 3

[0067] Also, the clay minerals and accelerators of component (A) in Tables 2 to 4 are as follows. <Clay minerals of component (A)> · Kasaoka clay: Clay minerals, manufactured by Kasanen Kogyo Co., Ltd., swelling degree 2 mL / 2 g · TB-250: Bentonite, manufactured by Tachibana Materials Co., Ltd., swelling degree 14 mL / 2 g · Smeton SA: Synthetic saponite, manufactured by Kunimine Industries Co., Ltd., swelling degree 45 mL / 2 g · Neoclay: Bentonite, manufactured by Hoojun Co., Ltd., swelling degree 18 mL / 2 g · Kunigel GS: Bentonite, manufactured by Kunimine Industries Co., Ltd., swelling degree 33 mL / 2 g

[0068] <Accelerator> · Calcium aluminate-based accelerator: Powder accelerator with calcium aluminate as the main component · Anhydrous gypsum: Manufactured by Sans-Es Gypsum Co., Ltd. · Sodium carbonate: Manufactured by Fujifilm Wako Pure Chemical Corporation · Sodium sulfate: Manufactured by Fujifilm Wako Pure Chemical Corporation · Sodium hydrogen carbonate: Manufactured by Fujifilm Wako Pure Chemical Corporation · Calcium hydroxide: Manufactured by Fujifilm Wako Pure Chemical Corporation · Potassium carbonate: Manufactured by Fujifilm Wako Pure Chemical Corporation

[0069] In addition, the hydraulic powder, aggregate, and dispersant in Table 4 were as follows. <(C) Hydraulic powder> · Ordinary cement: Ordinary Portland cement (two-component mixture: Taiheiyo Cement / Sumitomo Osaka Cement = 1 / 1, mass ratio), density 3.16 g / cm 3 · Blast furnace B-type cement: Manufactured by UBE Mitsubishi Cement Co., Ltd. · Quick-setting cement: Manufactured by Taiheiyo Cement Corporation · Eco-cement (1): Ordinary cement / metakaolin / calcium carbonate = 61 / 30 / 9 (mass%) · Eco-cement (2): Ordinary cement / metakaolin / fly ash / calcium carbonate = 54 / 26 / 12 / 8 (mass%) (Other powders) · Fly ash: Central fly ash, manufactured by Techno Central Co., Ltd. · Blast furnace slag: Manufactured by Essement, Nippon Steel Slag Products Co., Ltd. · Calcium carbonate: Neo Flow 150, manufactured by Shimizu Industry Co., Ltd. · Silica fume: Micro silica, manufactured by Elkem Japan Co., Ltd. · Metakaolin: Metamax, manufactured by SKW East Asia Co., Ltd. <Aggregate> · S: Fine aggregate (S): Shanyang-produced mountain sand, density 2.55 g / cm 3 · G: Kojima-produced crushed stone, density 2.63 g / cm3 <Dispersant> · Mitei 21HF: Polycarboxylic acid-based dispersant, active ingredient 24%, manufactured by Kao Corporation

[0070] <Measurement of the swelling degree of component (A)> (A) The swelling degree of the clay mineral was measured according to the swelling test method for bentonite (powdered) of JBAS 104:77 of the Japan Bentonite Industry Association. That is, 2.0 g of the sample adjusted to 8.0% by mass of moisture was added to a 100 mL stoppered graduated cylinder containing 100 mL of distilled water in about 10 portions. At this time, the next addition was made after the previous additive had deposited on the bottom of the graduated cylinder. When left standing for 24 hours, the apparent volume of the sample mass at the bottom of the graduated cylinder that had swelled was read from the scale of the graduated cylinder and taken as the swelling degree (mL / 2 g).

[0071] <Method for Measuring the Smectite Content of the Clay Mineral of Component (A)> (i) Drying Component (A) was placed in a hot air dryer and dried at 105 °C for 1 hour. (ii) Measurement of Methylene Blue Adsorption Capacity The methylene blue adsorption capacity of the clay mineral of component (A) was measured by the following method according to Japanese Industrial Standard (JIS Z 2451:2019). 1.87 g of methylene blue (molecular weight 374, manufactured by Fuji Film Wako Pure Chemical Corporation) was dissolved in 500 mL of ion-exchanged water to prepare a 10 mmol / L aqueous solution of methylene blue. Also, 1.68 g of sodium pyrophosphate decahydrate (molecular weight 446, manufactured by Sigma-Aldrich) was dissolved in 500 mL of ion-exchanged water to prepare a 0.2% by mass aqueous solution of sodium pyrophosphate. <Reagents> 10 mmol / L Aqueous Solution of Methylene Blue (Molecular Weight 374) Sodium Pyrophosphate (Na 4 P 2 O 7 ) 0.2% by Mass Aqueous Solution <Operating Method> About 0.4 g of component (A) was placed in a 100 mL screw tube, and 40 g of a 0.2% by mass aqueous solution of sodium pyrophosphate was added thereto. After dispersing this mixture with an ultrasonic cleaner (ASUCLEANER, ASU-3, manufactured by AS ONE Corporation) for 30 minutes, it was heated with warm water at 80 °C for 30 minutes. To the dispersed mixture, an aqueous solution of methylene blue at 10 mmol / L was added dropwise while stirring with a magnetic stirrer. Each time a predetermined amount was added dropwise, a part of the mixture was sucked up from the supernatant using a glass Pasteur pipette and dropped onto filter paper. The supernatant was dropped until a spot with a diameter of about 10 mm was formed on the filter paper. This operation was repeated until a halo was confirmed around the spot. When the halo was confirmed, the end point of the titration was taken when the width of the halo exceeded 2 mm. Then, based on the mass of the component (A) and the total addition amount of the 10 mmol / L methylene blue aqueous solution dropped until the end point, the methylene blue adsorption amount per 100 g of the component (A) was calculated. Specifically, the product of the titration volume (L) and the concentration of the methylene blue aqueous solution (10 mmol / L) was converted per 100 g of the component (A) to calculate the total methylene blue adsorption amount (mmol). (iii) Calculation of smectite content Adopting 140 mmol / 100 g as the methylene blue saturation adsorption amount of smectite, the smectite content of the clay mineral of the component (A) was calculated by dividing this saturation adsorption amount by the measured methylene blue adsorption amount of the component (A) and multiplying by 100.

[0072] <Measurement method of water content of component (A)> Approximately 2 g of the clay mineral of the component (A) was weighed into an aluminum cup and dried at 105 °C for 1 hour in a hot air dryer. The loss on drying was divided by the mass of the component (A) weighed before drying to calculate the water content of the clay mineral of the component (A). Note that the component (A) used was the component (A) that had undergone the following moisture absorption test.

[0073] <Moisture absorption test> The component (A) used was the one that had been left standing in a humidity atmosphere of the storage humidity (%RH) described in the table in advance for the storage time described in the table, the component (A) dried at 105 °C for 1 hour in a hot air dryer, and the component (A) that had been dried at 105 °C for 1 hour in a hot air dryer and then left standing in a humidity atmosphere of 85%RH for the storage time described in the table. In Tables 2 to 4, for the (A) component with the notation "dried", the one dried at 105°C for 1 hour was placed in a cup, and this cup was left standing for the storage time described in the table in a humidity atmosphere of the storage humidity (%RH) described in the table. For the (A) component without the notation "dried", the one stored in an environmental test chamber at 60%RH for one month or more was placed in a cup, and this cup was left standing for the storage time described in the table in a humidity atmosphere of the storage humidity (%RH) described in the table. Also, when storing the (A) component in a humidity atmosphere of 85%RH, a saturated aqueous potassium chloride solution was placed in the container for storing the (A) component to maintain the humidity in the container at 85%RH, and a cup containing the (A) component was left standing in the container with the humidity maintained at 85%RH. At this time, the cup was left standing in the container so that the (A) component did not come into contact with the saturated aqueous potassium chloride solution.

[0074] (2) Preparation of Sprayed Hydraulic Composition For the preparation of the sprayed hydraulic composition, a mortar mixer specified in "JIS R 5201 Physical Test Methods for Cement" was used. To the mixing bowl of the mortar mixer, 240 g of water, 400 g of cement, and 1054 g of sand in Table 1 were added and stirred at low speed for 2 minutes. When using the (A) component and the flash set retarder described in Table 2 or Table 3, the flash set retarder described in Table 3 was added, and it was stirred by hand for 5 seconds to obtain the sprayed hydraulic compositions of Examples 1-1 to 1-12 and Examples 2-1 to 2-15. Also, at 22°C, water, hydraulic powder (cement C and other powders), and aggregate S with the masses described in Table 4 were added to the mixing bowl of the mortar mixer and stirred at low speed for 2 minutes. The dispersant was premixed with water, and the aggregate G was mixed after obtaining the mortar, and then it was mixed by hand for 30 seconds. The (A) component and the flash set retarder were added to the obtained mortar, and it was stirred by hand for 5 seconds to obtain the sprayed hydraulic compositions of Examples 3-1 to 3-15. In Table 4, the blending amount of the dispersant is the blending amount of the active ingredient. Also, the water used for mixing was at 0°C, and the other materials were at 20°C, and a sprayed hydraulic composition at 15 to 17°C was obtained.

[0075] (3) Method for Measuring Slump 1,500 g of the sprayable hydraulic composition obtained in the above (2) was sprayed onto a wooden board 18 cm away from the discharge port of a powder and granular material conveying device (Bress Rider, model number K-40, manufactured by Bress Co., Ltd.). The pressure of the compressor connected to the powder and granular material conveying device was 0.6 MPa, and the inner diameter d of the discharge port was 3.5 cm. The humidity was appropriately adjusted to 60% RH or 80% RH, and the spraying test was carried out under such a humidity environment. Also, the volume ratio a / b of the air flow rate a for spraying the sprayable hydraulic composition onto the target surface to the flow rate b of the sprayed hydraulic composition was 14. Here, since the volume change of the hydraulic composition by mixing the component (A) is negligible, the flow rate of the sprayable hydraulic composition can be regarded as the flow rate b of the hydraulic composition. The air flow rate a was set to 22.5 L / min based on the specifications of the compressor (Toscon GP-4T8, manufactured by Toshiba Corporation). The flow rate b of the hydraulic composition was calculated as 1.66 L / min because 1,500 g (0.69 L) of the sprayable hydraulic composition was sprayed over 25 seconds. Also, the ratio L / d of the distance L from the mixing part of the clay mineral of the component (A) and the mortar to the discharge port for discharging the sprayable hydraulic composition to the inner diameter d of this discharge port was 3.25.

[0076] Among the sprayable hydraulic compositions sprayed onto the wooden board, those without the occurrence of noro adhered and laminated only at the spraying locations. On the other hand, for those with the occurrence of noro, it was confirmed that the paste component and a small amount of fine aggregate of the sprayable hydraulic composition flowed down directly below the spraying location. The mass of the sprayable hydraulic composition that fell directly below the wooden board and the mass of the sprayable hydraulic composition that adhered 8 cm below the wooden board were measured, and the noro occurrence rate (mass %) was calculated from the following formula (1). The lower this noro occurrence rate, the more it can be said that the occurrence of noro is suppressed when the sprayable hydraulic composition is sprayed. Noro occurrence rate (mass %) = 100 × [(mass of the sprayable hydraulic composition that fell directly below the wooden board) + (mass of the sprayable hydraulic composition that adhered 8 cm below the wooden board)] / (total mass of the sprayed sprayable hydraulic composition) (1)

[0077]

Table 2

[0078] As shown in Comparative Examples 1-2 to 1-5 in Table 2, the water content of the component (A) increases due to moisture absorption in an environment with a humidity of 80% RH or more. As a result, the norovirus generation rate is high when the spraying hydraulic composition is sprayed. In the spraying step of the present invention, even if the spraying step is carried out in such an environment with a humidity of 80% RH or more, the generation of norovirus can be effectively suppressed by setting the water content of the component (A) within a predetermined range.

[0079] [Table 3]

[0080] [Table 4]

Claims

1. (A) A spraying method in which a mixture of a clay mineral containing 30% by mass or more and 100% by mass or less of smectite when dry and having a moisture content of 0% by mass or more and 10% by mass or less is mixed with a hydraulic composition containing water, hydraulic powder, and aggregate, and the mixture is sprayed onto a target surface.

2. A spraying method in which the mixture is sprayed onto a target surface in an environment with a humidity of 80% RH or more.

3. The spraying method according to claim 1 or 2, wherein the swelling degree of the clay mineral is 10 mL / 2 g or more and 50 mL / 2 g or less.

4. The spraying method according to any one of claims 1 to 3, wherein the clay mineral and the hydraulic composition are mixed by being compressed air fed, respectively.

5. The spraying method according to any one of claims 1 to 4, wherein the pressure of the air sprayed onto the target surface is 0.2 MPa or more and 1.0 MPa or less.

6. The spraying method according to any one of claims 1 to 5, wherein a / b is a volume ratio of an air flow rate a for spraying the mixture onto a target surface to a flow rate b of the hydraulic composition sprayed onto the target surface, and is 10 or more and 100 or less.

7. The spraying method according to any one of claims 1 to 6, wherein a ratio L / d of a distance L from a mixing portion of the clay mineral and the hydraulic composition to an outlet for discharging the mixture to an inner diameter d of the outlet is 1 or more and 200 or less.

8. (A) A method for suppressing the generation of slag from a hydraulic composition to be sprayed, comprising mixing a clay mineral containing 30% by mass or more and 100% by mass or less of smectite when dry and having a moisture content of 0% by mass or more and 10% by mass or less with a hydraulic composition containing water, hydraulic powder, and aggregate, and spraying the resulting hydraulic composition to be sprayed onto a target surface.

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