Wet-type spray method

Abstract

To provide a wet-type spray method capable of reducing dust amount generated when spraying a hydraulic composition for spraying and preventing the hydraulic composition from spreading from a sprayed part, while ensuring sufficient productivity of spraying work.SOLUTION: A wet-type spray method comprises steps of: adding (b) clay mineral to a hydraulic composition including hydraulic powder, (a) polymer thickener and water and mixing them through a mixing work equal to or less than 150 J; and spraying the hydraulic composition including (b) component onto an object.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a wet spraying method using a hydraulic composition. [Background technology]

[0002] In order to prevent the collapse of exposed ground such as during tunnel excavation, a spraying method using quick-setting concrete, which is made by mixing an accelerator with concrete, is being used. Among these methods, the wet spraying method is usually carried out by preparing the shotcrete in a cement, aggregate, and water metered mixing plant installed at the excavation site, and transporting it to a transport / spraying machine with an agitator truck. The shotcrete and powdered accelerator are then mixed in a line that uses the pump of the spraying machine to pneumatically pump the shotcrete to the discharge outlet, and a junction pipe is installed midway between the line and a line that pneumatically pumps the powdered accelerator from the other side, and the quick-setting shotcrete is sprayed onto the ground surface until it reaches a specified thickness.

[0003] Patent Document 1 discloses a bentonite-blended shotcrete made of a mixture of cement, bentonite, fine aggregate, and water, in which the ratio of the mass of bentonite to the mass of cement is 20% by mass or less. It also discloses that this bentonite-blended shotcrete suppresses dust generation and reduces rebound during spraying. Patent Document 2 discloses a slump-reducing spray admixture that contains a clay mineral and an aluminum-containing substance. It also discloses that this slump-reducing spray admixture can significantly reduce the slump of cement concrete when sprayed, prevent sagging, and adjust the hardness to an appropriate level for trowel finishing. Patent Document 3 discloses a wet spraying method in which cement, water, aggregate, and solid polyethylene oxide are mixed to produce a hydraulic composition, a solid quick-setting agent is mixed with this hydraulic composition to produce a hydraulic composition for spraying, and the hydraulic composition for spraying is sprayed onto an object. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-026598 A [Patent Document 2] JP 2001-322850 A [Patent Document 3] JP 2021-155331 A Summary of the Invention [Problem to be solved by the invention]

[0005] Since the spray hydraulic composition is sprayed onto natural ground or the like under strong pressure, a mist of the spray hydraulic composition from the discharge port (main components of which are sand and cement in the spray hydraulic composition, hereinafter referred to as dust) or dust that rebounds when the spray hydraulic composition collides with the natural ground is generated, but from the viewpoint of improving the working environment, a reduction in the amount of this dust is desired. Furthermore, if the spray hydraulic composition spreads from the sprayed site when it is sprayed onto an object, it may take a long time to layer the spray hydraulic composition, resulting in a decrease in work efficiency. The present invention provides a wet spraying method which reduces the amount of dust generated when a sprayable hydraulic composition is sprayed, prevents the composition from spreading from the sprayed site, and ensures sufficient spraying work productivity. [Means for solving the problem]

[0006] The present invention relates to a wet spraying method in which a hydraulic composition containing hydraulic powder, (a) a polymer thickener (hereinafter referred to as component (a)), and water is mixed with (b) a clay mineral (hereinafter referred to as component (b)) at a stirring work of 150 J or less, and the hydraulic composition mixed with component (b) is sprayed onto an object. Effect of the Invention

[0007] According to the present invention, there is provided a wet spraying method which reduces the amount of dust generated when a sprayable hydraulic composition is sprayed, prevents the composition from spreading from the sprayed site, and ensures sufficient spraying work productivity. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a schematic diagram showing an outline of an evaluation device used for evaluating the hydraulic composition for spraying of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The mechanism by which the wet spraying method of the present invention reduces the amount of dust generated when a sprayable hydraulic composition is sprayed, prevents the composition from spreading from the sprayed area, and ensures sufficient spraying work productivity is not clear, but is presumed to be as follows. In the wet spraying method of the present invention, the clay mineral, which is component (b), is added to the hydraulic composition and mixed at a stirring work of 150 J or less, so that the clay mineral is present in the form of lumps without being kneaded into the hydraulic composition containing hydraulic powder, polymer thickener, and water. As a result, a coating of the hydraulic composition is formed around the clay mineral lumps, and it is presumed that this coating traps the clay mineral powder inside and prevents the clay mineral powder from flying up. The wet spraying method of the present invention is not limited to the above-mentioned mechanism of action.

[0010] The wet spraying method of the present invention is a wet spraying method in which (b) clay mineral (hereinafter referred to as (b) component) is added to a hydraulic composition containing hydraulic powder, (a) a polymer thickener (hereinafter referred to as (a) component) and water, and the mixture is mixed with a stirring work of 150 J or less, and the hydraulic composition mixed with (b) component is sprayed onto an object. In the following description, the hydraulic composition containing component (b) will also be referred to as the sprayable hydraulic composition of the present invention.

[0011] <Hydraulic composition for spraying> First, the sprayable hydraulic composition of the present invention used in the wet spraying method of the present invention will be described in detail. The hydraulic composition for spraying of the present invention contains a hydraulic powder, component (a), component (b) and water. The hydraulic composition for spraying of the present invention may be a composition obtained by mixing component (b) with a hydraulic composition containing hydraulic powder, component (a) and water.

[0012] The hydraulic powder used in the sprayable hydraulic composition of the present invention is a powder that hardens when mixed with water, and examples thereof include ordinary Portland cement, high-early-strength Portland cement, ultra-high-early-strength Portland cement, sulfate-resistant Portland cement, low-heat Portland cement, moderate-heat Portland cement, white Portland cement, and ecocement (e.g., JIS R5214, etc.). Among these, from the viewpoint of the spread of the sprayable hydraulic composition, cement selected from early-early-strength Portland cement, ordinary Portland cement, sulfate-resistant Portland cement, and white Portland cement is preferred, and early-early-strength Portland cement and ordinary Portland cement are more preferred.

[0013] The hydraulic powder may include blast furnace slag, fly ash, silica fume, anhydrous gypsum, etc., and may also include non-hydraulic limestone fine powder, etc. As the hydraulic powder, blast furnace cement, fly ash cement, or silica fume cement, which is a mixture of cement with blast furnace slag, fly ash, silica fume, etc., may also be used.

[0014] The spray hydraulic composition of the present invention preferably contains aggregate. Examples of the aggregate include aggregates selected from fine aggregates and coarse aggregates. The aggregate preferably contains fine aggregate. Examples of the fine aggregate include those specified by number 2311 in JIS A0203-2014. Examples of the fine aggregate include river sand, land sand, mountain sand, sea sand, lime sand, silica sand and crushed sands thereof, blast furnace slag fine aggregate, ferronickel slag fine aggregate, lightweight fine aggregate (artificial and natural), and recycled fine aggregate. Examples of the coarse aggregate include those specified by number 2312 in JIS A0203-2014. For example, examples of the coarse aggregate include river gravel, land gravel, mountain gravel, sea gravel, lime gravel, crushed stones thereof, blast furnace slag coarse aggregate, ferronickel slag coarse aggregate, lightweight coarse aggregate (artificial and natural), and recycled coarse aggregate. The fine aggregate and the coarse aggregate may be used in a mixture of different types, or a single type may be used. The sprayable hydraulic composition of the present invention preferably contains fine aggregate as an aggregate. The amount of fine aggregate used in the sprayable hydraulic composition of the present invention is preferably 800 kg / m 3 More preferably, 900kg / m 3 More than 1300 kg / m 3 Less than or equal to 1200 kg / m 3 The following is the result. 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 70% or less, more preferably 65% ​​or less. Here, the fine aggregate ratio is the volume content of fine aggregate in the total aggregate.

[0015] The hydraulic composition for spraying of the present invention has a water / hydraulic powder ratio (W / C) of preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, from the viewpoint of suppressing the spreading of the hydraulic powder, and preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 65% ​​by mass or less. That is, from the viewpoint of suppressing the spreading of the hydraulic powder, the hydraulic composition for spraying of the present invention contains water in an amount of preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, and preferably 80 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 65 parts by mass or less, per 100 parts by mass of the hydraulic powder. The water / hydraulic powder ratio (W / C) is the mass percentage (mass%) of water to the hydraulic powder in the hydraulic composition for spraying, and is calculated as (water / hydraulic powder)×100. In addition, when the hydraulic powder includes powders selected from powders having pozzolanic action, powders having latent hydraulic properties, and stone powder (calcium carbonate powder) in addition to powders having properties that harden through hydration reactions such as cement, the amounts of these powders are also included in the amount of hydraulic powder in the present invention. In addition, when the powder having properties that harden through hydration reactions contains a high-strength admixture, the amount of the high-strength admixture is also included in the amount of hydraulic powder. This also applies to other parts by mass that are related to the mass of the hydraulic powder.

[0016] Component (a) is a polymer thickener. Component (a) is at least one selected from an ether-based polymer compound, a cellulose-based polymer compound, and a polymer compound having a carboxy group, preferably at least one selected from an ether-based polymer compound and a cellulose-based polymer compound, and more preferably polyethylene oxide.

[0017] The ether-based polymer compound of component (a) includes a polymer or copolymer of alkylene glycol, for example, ethylene glycol. When the compound is an ethylene glycol polymer, from the viewpoint of hydrophilicity / hydrophobicity, the weight average molecular weight is preferably 100,000 or more and 10,000,000 or less.

[0018] When the component (a) is an ether-based polymer compound, furthermore polyethylene oxide, the weight average molecular weight of the ether-based polymer compound, furthermore polyethylene oxide, is preferably 200,000 or more, more preferably 400,000 or more, and preferably 10 million or less, more preferably 5 million or less, even more preferably 1.7 million or less, and further more preferably 1.5 million or less, from the viewpoint of suppressing the spreading of the hydraulic composition and suppressing dust.

[0019] The weight-average molecular weight of the ether-based polymer compound may be a value based on the product information (catalog, etc.) in the case of a commercially available product. Even if the weight-average molecular weight is unknown, since the weight-average molecular weight of the ether-based polymer compound correlates with the viscosity of the aqueous solution, for example, when the ether-based polymer compound is polyethylene oxide, the approximate value can be obtained by the following method. <Weight average molecular weight of polyethylene oxide> Using the polyethylene oxide to be measured, prepare aqueous solutions of various concentrations (hereafter referred to as sample aqueous solutions) by referring to the standard table below. Measure the viscosity of the sample aqueous solutions using a B-type viscometer at 25°C, No. 2 rotor, 30 rpm, and 1 minute later. However, if the viscosity exceeds 1000 mPa·s when measured with the No. 2 rotor, measure it using the No. 3 rotor under the same conditions as above (25°C, 30 rpm, and 1 minute later). From the viscosity obtained, determine the corresponding weight average molecular weight. Note that this standard table was created using polyethylene oxide with a known weight average molecular weight. In the standard table, PEO stands for polyethylene oxide. JPEG2024067807000001.jpg42153

[0020] The component (a) may be an aqueous solution of an ether-based polymer compound, or further, polyethylene oxide, or may be in a solid state. The solid ether-based polymer compound, and more preferably the polyethylene oxide, is preferably in the form of particles, more preferably powder or granules. Granules are generally particles having a relatively larger particle size than powder.

[0021] When the ether polymer compound of component (a), furthermore the polyethylene oxide, is in a solid state, the average particle size of component (a) is preferably 10 μm or more, more preferably 50 μm or more, and preferably 5,000 μm or less, more preferably 1,000 μm or less. This average particle size was measured using a laser diffraction / scattering type particle size distribution measuring device LA-920 (manufactured by Horiba, Ltd.) after ultrasonic irradiation using ethanol (ethanol (95), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a dispersion medium.

[0022] Examples of the cellulose-based polymer compound of the component (a) include modified celluloses, particularly alkyl- or hydroxyalkyl-modified celluloses such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose.

[0023] When the component (a) is a cellulose-based polymer compound, from the viewpoint of thickening of the slurry and handling properties, the viscosity of a 2% by mass aqueous solution or dispersion of the component (a) at 20°C at pH 12 is preferably 100 mPa·s or more, more preferably 500 mPa·s or more, even more preferably 1,000 mPa·s or more, and preferably 1,000,000 mPa·s or less, more preferably 500,000 mPa·s or less, even more preferably 100,000 mPa·s or less. This viscosity is measured using a B-type viscometer under conditions of 20°C, No. 2 rotor, 30 rpm, and 1 minute. However, if the viscosity exceeds 1,000 mPa·s when measured with the No. 2 rotor, it is measured under the same conditions as above (20°C, 30 rpm, 1 minute).

[0024] When component (a) is a cellulose-based polymer compound, from the viewpoints of thickening property and handleability, the weight average molecular weight of component (a) is preferably 50,000 or more, more preferably 100,000 or more, even more preferably 500,000 or more, and preferably 10,000,000 or less, more preferably 5,000,000 or less, even more preferably 2,000,000 or less. The weight average molecular weight is measured by gel permeation chromatography under the following measurement conditions. <Measurement conditions> Column: α-M + α-M (cation) Eluent: 50 mmоl / L LiCl, ethanol / water = 3:7 mass% mixture Flow rate: 0.6mL / min Column temperature: 40℃ Detector: RI Standard: Polyethylene glycol with known molecular weight

[0025] When component (a) is a cellulose-based polymer compound and is modified with an alkyl group, from the viewpoint of thickening property, the average number of hydroxyl groups substituted with alkyl groups per glucose ring unit of cellulose is preferably 4.0 or less, more preferably 3.5 or less, even more preferably 3.0 or less, and preferably 0.5 or more, more preferably 1.0 or more, even more preferably 1.5 or more.

[0026] When component (a) is a cellulose-based polymer compound and is modified with a hydroxyalkyl group, from the viewpoint of thickening property, the average molar number of hydroxyalkyl groups added per glucose ring unit of cellulose is preferably 1.00 or less, more preferably 0.70 or less, even more preferably 0.40 or less, and preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.10 or more.

[0027] The polymeric compound having a carboxy group of component (a) includes a polymeric compound having a weight average molecular weight of 20,000 to 6,500,000, which contains one or more monomers selected from acrylic acid and its salts, acrylic acid esters, methacrylic acid and its salts, methacrylic acid esters, and acrylamide (hereinafter referred to as monomer (A1)). The polymeric compound having a carboxy group is a polymer containing a structural unit derived from monomer (A1).

[0028] Examples of the salts of acrylic acid and methacrylic acid include sodium salts, potassium salts, ammonium salts, aluminum salts, and calcium salts. Examples of the acrylic acid ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, and glycidyl acrylate. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, and glycidyl methacrylate.

[0029] The monomer (A1) is preferably one or more monomers selected from acrylic acid and its salts, methacrylic acid and its salts, and acrylamide, more preferably one or more monomers selected from acrylic acid and its salts, and acrylamide, and even more preferably a monomer of acrylic acid or its salt.

[0030] The polymer compound having a carboxy group may contain a monomer (hereinafter referred to as monomer (A2)) other than the monomer (A1). Examples of the monomer (A2) include unsaturated carboxylic acids such as itaconic acid, maleic acid, fumaric acid, citraconic acid, aconitic acid, and crotonic acid, unsaturated carboxylic anhydrides such as maleic anhydride and citraconic anhydride, unsaturated carboxylic half esters such as monomethyl itaconate, monobutyl itaconate, and monoethyl maleate, unsaturated sulfonic acids such as vinyl sulfonic acid, methallyl sulfonic acid, and 2-(meth)acrylamido-2-methylpropanesulfonic acid, unsaturated phosphoric acids such as 2-((meth)acryloyloxy)ethyl phosphate and bis[2-((meth)acryloyloxy)ethyl] hydrogen phosphate, unsaturated phenols such as vinylphenol, ethylene, acryloyl Examples of the vinyl ester include cyanovinyls such as nitrile and methacrylonitrile, vinyl esters of aliphatic carboxylic acids having 3 to 18 carbon atoms, such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl octylate, and vinyl neodecanoate, vinyl ether monomers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and phenyl vinyl ether, polyfunctional vinyl monomers such as allyl methacrylate, unsaturated hydrocarbons such as styrene and butadiene, and unsaturated amide compounds such as methacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, and N-vinylpyrrolidone.

[0031] The proportion of the monomer (A1) in all the monomers constituting the polymer compound having a carboxy group is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, still more preferably 90 mol% or more, and preferably 100 mol% or less, and may be 100 mol%.

[0032] From the viewpoint of adhesion and dust suppression of the hydraulic composition, the polymer compound having a carboxy group is preferably one or more selected from polyacrylic acid and its salts, polymethacrylic acid and its salts, and polyacrylamide, more preferably one or more selected from polyacrylic acid and its salts, and polyacrylamide, and even more preferably polyacrylic acid or its salts.

[0033] The weight average molecular weight of the polymer compound having a carboxy group is, from the viewpoints of adhesion of the hydraulic composition and dust suppression, preferably 20,000 or more, more preferably 50,000 or more, even more preferably 100,000 or more, still more preferably 200,000 or more, and preferably 6.5 million or less, more preferably 5 million or less, still more preferably 3.5 million or less, still more preferably 2.5 million or less, and still more preferably 2 million or less.

[0034] The weight average molecular weight of a polymer compound having a carboxy group is determined by gel permeation chromatography under the following conditions, using a mixed solvent of acetonitrile and water (phosphate buffer) as a developing solvent and polyethylene glycol as a standard substance. Column: GMPWXL-GMPWXL (anion) manufactured by Tosoh Corporation Detector: Differential refractometer Eluent: 0.2M phosphate buffer / acetonitrile = 9 / 1 Standards: Polyethylene glycol equivalent (monodisperse polyethylene glycol with known molecular weights, molecular weights: 21,000, 44,200, 101,000, 185,000, 580,000, 977,000) Conditions: Column temperature: 40°C, flow rate: 0.5mL / min, concentration: 2mg / mL

[0035] The hydraulic composition for spraying of the present invention contains component (a) in an amount of preferably 0.001% by mass or more, more preferably 0.002% by mass or more, even more preferably 0.003% by mass or more, and still more preferably 0.004% by mass or more from the viewpoint of adhesion of the hydraulic composition and dust suppression, and preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and even more preferably 0.02% by mass or less from the viewpoint of dischargeability of the hydraulic composition.

[0036] The hydraulic composition for spraying of the present invention contains component (a) in an amount of preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.05% by mass or more, based on the hydraulic powder in the hydraulic composition for spraying, from the viewpoints of adhesion of the hydraulic composition and dust suppression, and preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less, from the viewpoint of ejection workability of the hydraulic composition.

[0037] <(b) Component> Component (b) is a clay mineral. From the viewpoint of the spread of the sprayable hydraulic composition, the clay mineral is preferably a clay mineral having a swelling degree of 15 mL / 2 g or more and 50 mL / 2 g or less.

[0038] The swelling degree of the clay mineral of component (b) is, from the viewpoint of the spread of the sprayable hydraulic composition, 15 mL / 2 g or more, preferably 20 mL / 2 g or more, and 50 mL / 2 g or less, preferably 45 mL / 2 g or less, more preferably 40 mL / 2 g or less. This degree of swelling is measured according to the swelling test method for bentonite (powdered) in JBAS104:77 of the Japan Bentonite Industry Association. That is, 2.0 g of sample adjusted to 8.0% moisture by mass is added in about 10 separate portions to a 100 mL stoppered measuring cylinder containing 100 mL of distilled water. The next addition is made after the previous addition has settled to the bottom of the measuring cylinder. After leaving it for 24 hours, the apparent volume of the swollen sample mass at the bottom of the measuring cylinder is read from the graduations on the measuring cylinder and expressed as the degree of swelling (mL / 2g).

[0039] The clay mineral of component (b) may be a cation-exchangeable layered silicate. One example of such a clay mineral may be one or more clay minerals selected from smectite and bentonite. Smectite is a group of cation-exchangeable layered silicates belonging to clay minerals, and examples of natural products include montmorillonite, which is well known as the main component of bentonite, as well as beidellite, hectorite, saponite, nontronite, etc., and examples of synthetic products include swelling fluorine-based micas, etc. Among these, the clay mineral contained in the spray hydraulic composition of the present invention is preferably a clay mineral selected from bentonite, saponite, hectorite, and montmorillonite, more preferably a clay mineral selected from bentonite and montmorillonite, and even more preferably bentonite, from the viewpoint of adhesion and dust suppression of the hydraulic composition. The content of the clay mineral selected from bentonite, saponite, hectorite and montmorillonite in the clay minerals contained in the hydraulic composition for spraying is preferably 60 mass% or more, more preferably 100 mass%, and further preferably the content of bentonite is 100 mass%.

[0040] The hydraulic composition for spraying of the present invention contains component (b) in an amount of preferably 0.02% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, and preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less, from the viewpoints of adhesion of the hydraulic composition and dust suppression.

[0041] The hydraulic composition for spraying of the present invention contains component (b) in an amount of preferably 0.1 mass % or more, more preferably 0.3 mass % or more, even more preferably 0.5 mass % or more, and preferably 3 mass % or less, more preferably 2.5 mass % or less, even more preferably 2 mass % or less, based on the hydraulic powder in the hydraulic composition for spraying, from the viewpoints of adhesion of the hydraulic composition and dust suppression.

[0042] In the hydraulic composition for spraying of the present invention, the mass ratio (b) / (a) of the content of the component (b) to the content of the component (a) is preferably 1.0 or more, more preferably 2.5 or more, even more preferably 5.0 or more, from the viewpoint of suppressing dust in the hydraulic composition, and is preferably 50 or less, more preferably 40 or less, even more preferably 25 or less, and even more preferably 15 or less, from the viewpoint of suppressing dust in the hydraulic composition.

[0043] The hydraulic composition for spraying of the present invention contains water. Examples of water include tap water, groundwater, lake water, and river water.

[0044] <Accelerating agent> The sprayable hydraulic composition of the present invention may optionally contain an accelerator. The accelerator is preferably a powder accelerator. The accelerator is, for example, one or more accelerators selected from a cement mineral-based accelerator and an aluminum-based accelerator.

[0045] The cement mineral-based quick-setting admixture may be at least one selected from calcium aluminate, calcium sulfoaluminate, and calcium aluminate. The aluminum-based quick-setting admixture may be at least one selected from aluminum salts including 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 adhesion and strength development of the hydraulic composition, the quick-setting admixture 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 even more preferably one or more selected from calcium aluminate and aluminum sulfate.

[0046] In the spray hydraulic composition of the present invention, an additive for spray hydraulic composition (hereinafter referred to as the additive of the present invention), which is a mixture of the above component (b) and a quick-setting admixture, may be used. The additive is mixed with the hydraulic composition containing hydraulic powder and water when the spray hydraulic composition is sprayed. The additive of the present invention contains a quick-setting admixture in an amount of preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and preferably 98% by mass or less, more preferably 96% by mass or less, even more preferably 95% by mass or less, from the viewpoints of adhesion and strength development of the hydraulic composition.

[0047] In the additive of the present invention, the mass ratio of the content of the (b) component to the content of the quick-setting admixture, (quick-setting admixture) / (b), is, from the viewpoints of adhesion and strength development of the hydraulic composition, preferably 3 or more, more preferably 4 or more, even more preferably 4.5 or more, and is preferably 90 or less, more preferably 50 or less, even more preferably 25 or less, still more preferably 20 or less, still more preferably 18 or less, and even more preferably 15 or less.

[0048] When the hydraulic composition for spraying of the present invention contains a quick-setting admixture, the hydraulic composition for spraying of the present invention contains, from the viewpoints of adhesion and strength expression of the hydraulic composition, preferably 4 parts by mass or more, more preferably 6 parts by mass or more, even more preferably 6.5 parts by mass or more, still more preferably 7 parts by mass or more, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less of the quick-setting admixture per 100 parts by mass of the hydraulic powder.

[0049] When the hydraulic composition for spraying of the present invention contains a quick-setting admixture, the mass ratio of the content of the component (b) to the content of the quick-setting admixture, (quick-setting admixture) / (b), in the hydraulic composition for spraying of the present invention, is preferably 3 or more, more preferably 4 or more, even more preferably 4.5 or more, and is preferably 90 or less, more preferably 50 or less, even more preferably 25 or less, still more preferably 20 or less, still more preferably 18 or less, and even more preferably 15 or less, from the viewpoints of adhesion and strength development of the hydraulic composition.

[0050] The hydraulic composition for spraying of the present invention may optionally contain a high-performance water-reducing agent, a high-performance AE water-reducing agent, a water-reducing agent containing an AE water-reducing agent and a superplasticizer, an expansive material, a hardening accelerator, a hardening retarder, a polymer for cement, a foaming agent, a waterproofing agent, a rust inhibitor, a shrinkage reducing agent, a pigment, a fiber, a water repellent, an efflorescence inhibitor, and the like (excluding those corresponding to component (a)).

[0051] <Wet spraying method> The present invention provides a wet spraying method, which comprises adding a clay mineral (b) to a hydraulic composition containing hydraulic powder, a polymer thickener (a) and water, mixing them with a stirring work of 150 J or less, and spraying the hydraulic composition mixed with the (b) component onto an object. The wet spraying method of the present invention may be a wet spraying method in which component (b) is added to a hydraulic composition containing hydraulic powder, a polymer thickener as component (a), and water, and the mixture is mechanically mixed at a stirring work of 150 J or less, and the hydraulic composition mixed with component (b) is sprayed onto an object. The present invention also provides a wet spraying method, which comprises adding component (b) to a hydraulic composition obtained by mixing hydraulic powder, component (a), and water, and mechanically mixing the mixture with a stirring work of 150 J or less to produce a hydraulic composition for spraying, and then spraying the hydraulic composition for spraying onto an object. In the wet spraying method of the present invention, the hydraulic composition or the hydraulic composition for spraying may be mixed with an accelerator, and the hydraulic composition or the hydraulic composition for spraying mixed with the accelerator may be sprayed onto an object. In the wet spraying method of the present invention, examples of objects to which the sprayable hydraulic composition is sprayed include roads, railways, tunnels such as water conduits, and slopes formed by natural excavation, banking, and the like.

[0052] In the wet spraying method of the present invention, the hydraulic powder, component (a), component (b), water and quick-setting admixture are the same as those described in the hydraulic composition for spraying of the present invention. The wet spraying method of the present invention can be appropriately applied to the embodiments described in the spray hydraulic composition of the present invention. The preferred content of the spray hydraulic composition of the present invention can be applied by replacing it with the preferred mixing amount in the wet spraying method of the present invention. In addition, the mixing of the hydraulic composition and the component (b) can be performed using a mixing method in which mechanical force is applied after the hydraulic composition and the component (b) are brought into contact with each other, and a mixing method in which mechanical force is not applied. Examples of the mixing method in which mechanical force is applied (mechanical mixing) include a method in which a stirring blade is rotated in a container containing the objects to be mixed, and a method in which a container containing the objects to be mixed is rotated. Examples of the mixing method in which mechanical force is not applied include a method in which the flow path of the objects to be mixed is controlled, and a method in which collision or suction is caused by the pressure of the objects to be mixed. In mixing methods that apply mechanical force (mechanical mixing), the mixing work exceeds 0 J, while in mixing methods that do not apply mechanical force, the mixing work is 0 J. As a mixing method, the stirring work when adding the (b) component to the hydraulic composition and mechanically mixing is preferably more than 0 J and less than 150 J from the viewpoint of adhesion of the hydraulic composition and dust suppression.

[0053] In the wet spraying method of the present invention, the mixing work (J) is calculated by the product of the mixing power (P) and the mixing time (s), as shown in the following formula (1). For example, in the case of mechanical mixing using an impeller, the stirring power is N P The power number can be calculated by the "Nagata formula" shown in the following formula (2) described in the reference (Nagata Shinji, Yamamoto Kazuo, Yokoyama Tohei, Shiga Shujiro, Chemical Engineering, 21, 708-715 (1957)). In addition, N in formula (1) p and N in Eq. (2) p0 indicates the power number, N p =N p0 It is. Moreover, Re (Reynolds number) in the following formula (2) can be calculated by the following formula (3). Mixing work = mixing power P × mixing time t (1) Stirring power: P=N P ρn 3 d 5 N P :Number of power n: Rotor speed (1 / s) b: Wingspan (m) d: Blade diameter (m) D: Diameter of mixing vessel (m) H: Depth of mortar in mixing tank (m) Re: Reynolds number ρ: specific gravity of hydraulic composition μ: Viscosity of hydraulic composition

[0054]

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[0055] The wet spraying method of the present invention will be described in detail with reference to a specific example, but the wet spraying method of the present invention is not limited to this specific example. In the wet spraying method of the present invention, first, a hydraulic composition is produced by mixing hydraulic powder, component (a), water, and optionally aggregate. The hydraulic composition produced by mixing hydraulic powder, component (a), water and optionally aggregate has a water / hydraulic powder ratio (W / C) [the mass percentage (mass%) of water and hydraulic powder in the hydraulic composition] of preferably 30 mass% or more, more preferably 40 mass% or more, even more preferably 50 mass% or more, and preferably 80 mass% or less, more preferably 70 mass% or less, even more preferably 65 mass% or less, from the viewpoint of adhesion of the hydraulic composition. Usually, the water / hydraulic powder ratio of the hydraulic composition is reflected in the subsequently produced hydraulic composition for spraying. Therefore, in the present invention, the water / hydraulic powder ratio of the hydraulic composition for spraying is also preferably within the above range.

[0056] In the present invention, the (a) component is mixed in an amount of preferably 0.01 part by mass or more, more preferably 0.02 part by mass or more, and even more preferably 0.05 part by mass or more, relative to 100 parts by mass of the hydraulic powder in the hydraulic composition, from the viewpoints of adhesion of the hydraulic composition and dust suppression, and from the viewpoint of discharge workability of the hydraulic composition, preferably 1.0 part by mass or less, more preferably 0.5 part by mass or less, and even more preferably 0.3 part by mass or less. That is, in the present invention, the component (a) is mixed with the hydraulic powder in the hydraulic composition in an amount of preferably 0.01 mass % or more, more preferably 0.02 mass % or more, even more preferably 0.05 mass % or more, and preferably 1.0 mass % or less, more preferably 0.5 mass % or less, even more preferably 0.3 mass % or less, from the viewpoints of adhesion of the hydraulic composition and dust suppression.

[0057] In the present invention, the hydraulic powder, component (a), water, aggregate, and other optional components can be mixed by a known method. Specifically, the hydraulic powder, water, and aggregate can be mixed simultaneously. A mixing mixer such as a mortar mixer, a flow mixer, a mixer pump, a pan-type forced mixer, a two-shaft forced mixer, or a tilting mixer can be used to mix these components.

[0058] In the present invention, the hydraulic composition obtained by mixing hydraulic powder, water, and an arbitrary aggregate is added with component (b), mechanically mixed at a stirring work of 150 J or less, and an accelerator is added as needed to produce a hydraulic composition for spraying. The stirring work is added to the hydraulic composition after adding component (b) to the hydraulic composition. A mixing mixer such as a mortar mixer, a flow mixer, a mixer pump, a pan-type forced mixer, a two-shaft forced mixer, or a tilting mixer can be used to mechanically mix the hydraulic composition and component (b). In addition, component (b) and an accelerator may be mixed with the hydraulic composition. When the accelerator is a powder, a powdery mixture of component (b) and the accelerator may be prepared in advance. The hydraulic composition and the quick-setting admixture can be mixed, for example, by a general wet spraying method in which the hydraulic composition and the quick-setting admixture are mixed together by compressed air. Mixing by compressed air does not correspond to mechanical mixing, and the stirring work by mechanical mixing is 0 J. It is preferable to mix the component (b) by adding it, from the viewpoint of uniformly dispersing the component (b) in the hydraulic composition for spraying.

[0059] The stirring work when adding and mixing the (b) component to the hydraulic composition is, from the viewpoint of adhesion of the hydraulic composition and dust suppression, 150 J or less, preferably 120 J or less, more preferably 50 J or less, even more preferably 20 J or less, even more preferably 10 J or less, and preferably 0 J or more, more preferably more than 0, even more preferably 3 J or more. In the present invention, it is preferable to mix component (b) with a hydraulic composition containing hydraulic powder, component (a) and water, mechanically mix the hydraulic composition mixed with component (b) with a stirring work of 150 J or less, preferably 120 J or less, more preferably 50 J or less, even more preferably 20 J or less, even more preferably 10 J or less, and preferably more than 0, more preferably 3 J or more, and spray the obtained hydraulic composition for spraying onto an object.

[0060] In the present invention, the (b) component is mixed in an amount of preferably 0.1 part by mass or more, more preferably 0.2 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the hydraulic powder in the hydraulic composition, from the viewpoints of adhesion of the hydraulic composition and dust suppression, and from the viewpoint of discharge workability of the hydraulic composition, preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 2.5 parts by mass or less. That is, in the present invention, the (b) component is mixed with the hydraulic powder in the hydraulic composition in an amount of preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more from the viewpoint of adhesion of the hydraulic composition and dust suppression, and preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 2.5% by mass or less from the viewpoint of discharge workability of the hydraulic composition.

[0061] In the present invention, in the hydraulic composition into which the (b) component is mixed, the mass ratio (b) / (a) of the amount of the (b) component mixed to the amount of the (a) component mixed is preferably 1.0 or more, more preferably 2.5 or more, even more preferably 5.0 or more, from the viewpoint of suppressing dust in the hydraulic composition, and is preferably 50 or less, more preferably 40 or less, even more preferably 25 or less, and even more preferably 15 or less, from the viewpoint of suppressing dust in the hydraulic composition.

[0062] In the present invention, when the quick-setting admixture is used, the quick-setting admixture is mixed in an amount of preferably 4 parts by mass or more, more preferably 6 parts by mass or more, even more preferably 6.5 parts by mass or more, still more preferably 7 parts by mass or more, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the hydraulic powder in the hydraulic composition, from the viewpoint of strength development of the hydraulic composition.

[0063] In the present invention, when the quick-setting admixture is used, the mass ratio of the mixed amount of the component (b) to the mixed amount of the quick-setting admixture, (quick-setting admixture) / (b), is, from the viewpoints of adhesion of the hydraulic composition and dust suppression, preferably 3 or more, more preferably 4 or more, even more preferably 4.5 or more, and is preferably 90 or less, more preferably 50 or less, even more preferably 25 or less, still more preferably 20 or less, still more preferably 18 or less, and even more preferably 15 or less.

[0064] In the wet spraying method of the present invention, the thus prepared hydraulic composition for spraying is sprayed onto an object. The wet spraying method of the present invention can be carried out by using conventional spraying equipment. The spraying equipment may be any equipment that can perform wet spraying without any problems, and for example, it is possible to use "Ariva 280" manufactured by Arriba for pumping the hydraulic composition, and "Natmcrete" manufactured by Chiyoda Seisakusho for pumping the quick-setting admixture, and mix the two to prepare a hydraulic composition for spraying, which can then be sprayed. EXAMPLES

[0065] (1) Preparation of hydraulic composition for spray application The components of the spray hydraulic composition are as follows: <Components of hydraulic composition for spray application> <Hydraulic composition> Water: Tap water Cement (hydraulic powder): A 1:1 mixture of ordinary Portland cement manufactured by Taiheiyo Cement Corporation and ordinary Portland cement manufactured by Sumitomo Osaka Cement Corporation. Aggregate (sand): Mountain sand from Joyo City, Kyoto Prefecture Surface-dried specific gravity: 2.55 <Component (a): Polymer thickener> PEO: Polyethylene oxide, weight average molecular weight (Mw) 800,000, average number of moles added 1,816 mol, (product name) Alcox, manufactured by Meisei Chemical Industry Co., Ltd. <(b) Component: Clay minerals> Clay minerals: Bentonite, Kunigel GS, manufactured by Kunimine Kogyo Co., Ltd., swelling degree 33mL / 2g

[0066] The swelling degree of clay minerals was measured according to the swelling test method for bentonite (powdered) in JBAS104:77 of the Japan Bentonite Industry Association. That is, 2.0 g of sample adjusted to 8.0 mass% moisture was added in about 10 separate portions to a 100 mL stoppered measuring cylinder containing 100 mL of distilled water. The next addition was made after the previous addition had settled to the bottom of the measuring cylinder. After leaving it for 24 hours, the apparent volume of the swollen sample mass at the bottom of the measuring cylinder was read from the graduations on the measuring cylinder and was taken as the swelling degree (mL / 2g).

[0067] The hydraulic composition was prepared using a mortar mixer as specified in "JIS R 5201 Physical Test Methods for Cement." 240g of water, 400g of hydraulic powder, and 1054g of sand were added to the mixing bowl of a mortar mixer and mixed at low speed for 2 minutes. Polyethylene oxide was added at the same time as the sand. Clay mineral was added to the obtained hydraulic composition and mixed for the mixing time shown in the table to obtain a hydraulic composition for spraying. The mixing condition of the mortar mixer was set to low speed (n=4.75 (1 / s)).

[0068] <Calculation of mixing work> Based on the above formulas (1) to (3), after the clay mineral was added to the hydraulic composition, the stirring work applied to the hydraulic composition by mechanical mixing was calculated. Mixing work = mixing power P × mixing time t (1) Stirring power: P=N P ρn 3 d 5 N P : Power number (calculated based on the "Nagata formula" in (2) above) n: Rotor speed = 4.75 (1 / s) b: Wingspan = 0.14(m) d: Blade diameter=0.14(m) D: Diameter of mixing vessel = 0.215 (m) H: Depth of mortar in mixing tank = 0.052 (m) Re: Reynolds number (calculated based on the above formula (3)) ρ: Specific gravity of sprayed hydraulic composition (mortar) = 2.17 kg / m 3 μ: Viscosity of the sprayable hydraulic composition (mortar) (measured by the viscosity measurement method described below and shown in Table 1) However, in Example 1-7, the rotor was changed to have a blade width of 0.10 (m) and a blade diameter of 0.07 (m), and in Example 1-8, the rotation speed of the rotor was changed to 2.33 (1 / s).

[0069] <Method of measuring viscosity> 300 mL of the spray hydraulic composition in Table 1 was placed in a measuring beaker, and the viscosity of the spray hydraulic composition was measured using a cylindrical rotational viscometer (VISCOTESTER VT-04E, manufactured by Rion Co., Ltd.). Rotor No. 1 (rotation speed: 62.5 rpm) was used. The measurement temperature was 20°C, and the viscosity was measured 1 minute after the start of measurement. The viscosity is the viscosity of the spray hydraulic composition after stirring.

[0070] (2) Evaluation (2-1) Evaluation of spread rate and dust amount 1,500 g of the obtained hydraulic composition for spraying was sprayed onto a wooden board 3 located 18 cm away from the nozzle 2 of the powder / granule conveying device 1 (Breath Rider, model number K-20, manufactured by Breath Co., Ltd.) shown in Figure 1. The wooden board 3 was provided inside a resin box 4. The box 4 had an inner wall 4a on which the wooden board 3 was provided and an opening 4b facing the inner wall 4a, and a lid 4c was provided at the opening 4b to close the opening 4b. An opening 4d through which the nozzle 2 of the powder / granular material conveying device 1 was inserted was formed in the lid 4c, and the powder / granular material conveying device 1 was provided by inserting the nozzle 2 into the opening 4d. An opening 4e through which a filter 6 was provided was also formed in the lid 4c, and air was supplied from a compressor 5 to the powder / granular material conveying device 1, and the air was sprayed from the nozzle 2 into the box 4 and discharged outside the box 4 through the filter 6. The pressure of the compressor 5 connected to the powder / granular material conveying device 1 was 0.6 MPa, and the aperture diameter φ of the opening of the injection port 2 was 2 cm. In addition, as the filter 6, one sheet of kitchen paper (Elleair Super Absorbent Kitchen Towel, manufactured by Daio Paper Corporation) was used. The mass of the spray hydraulic composition attached inside a circle with a diameter of 12 cm centered at the center of the spray hydraulic composition sprayed on the wooden board 3 and the mass of the spray hydraulic composition attached outside this circle were measured, and the spreading rate (%) was calculated by the following formula (4). It can be said that the lower the spreading rate, the more the spray hydraulic composition is suppressed from spreading from the sprayed area when sprayed. Spreading rate (%) = 100 × (mass of the spray hydraulic composition attached to the outside of a circle with a diameter of 12 cm) / (mass of the spray hydraulic composition attached to the inside of a circle with a diameter of 12 cm) (4)

[0071] In addition, the dust-covered kitchen paper (filter 6) was visually observed, and the amount of dust in the wet spraying method of the embodiment was evaluated based on the following evaluation criteria. The higher the value, the more the amount of dust has been reduced. [Dust volume evaluation index] 1: The entire area is clearly colored gray. 2: The whole or part is colored light gray. 3: No coloring at all

[0072] In addition, after spraying the hydraulic composition for spraying, the lightness (L * The lightness of the kitchen paper was measured using a color difference meter (TES-135A, manufactured by Sato Shoji Co., Ltd.). When measuring the lightness of the kitchen paper, the kitchen paper was placed on top of three sheets of copy paper in order to reduce the influence of the measurement table. * The higher the value, the more the amount of dust is reduced.

[0073] [Table 1] [Explanation of symbols]

[0074] 1. Powder and granular material transport device 3 wood board 4 boxes 4c Lid 6 Filters

Claims

1. A wet spraying method in which (b) a clay mineral (hereinafter referred to as (b) component) is added to a hydraulic composition containing hydraulic powder, (a) a polymer thickener (hereinafter referred to as (a) component), and water, and the mixture is mixed with a stirring work of 150 J or less, and the hydraulic composition mixed with (b) component is sprayed onto an object.

2. 2. The wet spraying method according to claim 1, wherein component (b) is added to the hydraulic composition and mechanically mixed at a stirring work of 150 J or less.

3. 3. The wet spraying method according to claim 1, wherein the component (a) is polyethylene oxide.

4. 3. The wet spraying method according to claim 1 or 2, wherein in the hydraulic composition containing the component (b), the mass ratio (b) / (a) of the amount of the component (b) mixed to the amount of the component (a) mixed is 1.0 or more and 50 or less.

5. 3. The wet spraying method according to claim 1, wherein the component (b) is a clay mineral having a swelling degree of 10 mL / 2 g or more and 50 mL / 2 g or less.

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