Hydraulic composition for spraying
Patent Information
- Application Number
- JP2022178149
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-11-07
- Publication Date
- 2025-10-23
Smart Images
Figure 00000015_0000
Abstract
Description
[Technical field]
[0001] The present invention relates to a hydraulic composition for spraying and a spraying method using the hydraulic composition for spraying. [Background technology]
[0002] In order to prevent the collapse of exposed ground during tunnel excavation, etc., a spraying method using quick-setting concrete or quick-setting mortar is being used. In this method, the concrete is usually prepared at a cement, aggregate, and water metered mixing plant installed at the excavation site, and then transported to a transport / spraying machine with an agitator truck. The sprayed concrete and quick-setting mortar are then mixed together in a line that uses the pump of the spraying machine to pneumatically pump the sprayed concrete to the discharge outlet, and a junction pipe is installed midway between the two lines to pneumatically pump the quick-setting mortar from the other side, and the mixture is sprayed onto the ground surface to a specified thickness as quick-setting shotcrete.
[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 spraying method in which a hydraulic composition is produced by mixing cement, water, aggregate, and solid polyethylene oxide, this hydraulic composition is mixed with a solid quick-setting agent to produce a hydraulic composition for spraying, and the hydraulic composition for spraying is sprayed onto an object. Patent Document 4 discloses a quick-setting concrete containing cement, fine aggregate, and polyethylene glycol. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] JP 2004-026598 A [Patent Document 2] JP 2001-322850 A [Patent Document 3] JP 2019-64909 A [Patent Document 4] JP 2003-146716 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. In addition, since the hydraulic composition for spraying starts hardening within a few seconds after adding the quick-setting agent, it easily adheres to the pipes and nozzles of the spraying machine, and when the work is performed continuously, the hydraulic composition for spraying gradually accumulates, causing a decrease in the discharge amount of the hydraulic composition for spraying, or an unstable discharge amount causing a pulsating phenomenon, which deteriorates the workability. In such cases, the problem can be solved by cleaning the pipes and nozzles, but the work efficiency decreases significantly as the cleaning frequency increases. In recent years, there has been a demand for improved work efficiency in large objects such as the Linear Shinkansen. The present invention provides a hydraulic composition for spraying that can suppress adhesion to the piping and nozzle of a spraying machine and reduce the amount of dust generated when the hydraulic composition for spraying is sprayed. [Means for solving the problem]
[0006] The present invention relates to a hydraulic composition for spraying, which contains hydraulic powder, fine aggregate, (A) polyethylene oxide (hereinafter referred to as component (A)), optionally (B) a clay mineral (hereinafter referred to as component (B)), and water, wherein the fine aggregate and component (B) have a total methylene blue adsorption amount of 0.37 mmol or more per 100 g of the total content of the fine aggregate and component (B) measured in accordance with JIS Z2451:2019.
[0007] The present invention also relates to a spraying method in which the above-mentioned sprayable hydraulic composition is sprayed onto a target surface. Effect of the Invention
[0008] According to the present invention, there are provided a hydraulic composition for spraying and a spraying method which can suppress adhesion to the piping and nozzle of a spraying machine and reduce the amount of dust generated when the hydraulic composition for spraying is sprayed. [Brief description of the drawings]
[0009] [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
[0010] The present invention relates to a sprayable hydraulic composition, and more particularly to a cement admixture, a cement composition, and a spraying method using the same, which are used when spraying quick-setting concrete or quick-setting mortar on tunnels for roads, railways, and water conduits, and on slopes formed by natural ground excavation, embankment, etc. The sprayable hydraulic composition in the present invention is a general term for cement mortar and cement concrete.
[0011] The mechanism by which the spray hydraulic composition of the present invention can suppress adhesion to the piping and nozzle of a spray machine and reduce the amount of dust generated when the spray hydraulic composition is sprayed is not clear, but is presumed to be as follows. Component (A) has the property of adsorbing to the silica content of sand, which is the main component of dust, and it is described in Patent Document 3 (JP 2019-64909) that the molecular chains of component (A) bind the dust (sand) and thereby reduce the amount of dust. As a result of intensive research, the inventors have found that, while component (B) alone does not affect dust or adhesion to the pipes and nozzles of a spraying machine, the combined use of components (A) and (B) produces an interaction that can simultaneously reduce the amount of dust and inhibit adhesion to the pipes and nozzles of a spraying machine. Then, taking into consideration component (B) contained in fine aggregate, the inventors have completed the present invention. The sprayable hydraulic composition and spraying method of the present invention are not limited to the above-mentioned mechanism of action.
[0012] <Hydraulic composition for spraying> The sprayable hydraulic composition of the present invention contains hydraulic powder, fine aggregate, (A) polyethylene oxide (hereinafter referred to as component (A)), optionally (B) a clay mineral (hereinafter referred to as component (B)), and water.
[0013] 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.
[0014] 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.
[0015] The sprayable hydraulic composition of the present invention contains an aggregate. The aggregate may be selected from fine aggregate and coarse aggregate. The sprayable hydraulic composition of the present invention contains at least fine aggregate as the aggregate. Examples of fine aggregates include those specified by number 2311 in JIS A0203-2014. Examples of fine aggregates 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. Furthermore, examples of coarse aggregate include those specified by number 2312 in JIS A0203-2014. For example, examples of coarse aggregate include river gravel, land gravel, mountain gravel, sea gravel, limestone gravel, crushed stones thereof, blast furnace slag coarse aggregate, ferro-nickel slag coarse aggregate, lightweight coarse aggregate (artificial and natural), and recycled coarse aggregate. Fine aggregate and coarse aggregate of different types may be mixed and used, or a single type may be used. The sprayable hydraulic composition of the present invention contains fine aggregate as an aggregate. The amount of fine aggregate used in the sprayable hydraulic composition of the present invention is preferably 500 kg / m 3 More preferably, 600 kg / m 3 More than 2000 kg / m 3 Less than or equal to 1700 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.
[0016] The water / hydraulic powder ratio (W / C) of the sprayable hydraulic composition of the present invention is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, from the viewpoints of suppressing adhesion to the nozzle, reducing dust, and furthermore, of expressing strength to prevent the sprayable hydraulic composition from collapsing, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% by mass or less. That is, from the viewpoint of strength development, the hydraulic composition for spraying of the present invention contains water in an amount of preferably 30 parts by mass or more, more preferably 35 parts by mass or more, even more preferably 40 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, relative to 100 parts by mass of the hydraulic powder. The water / hydraulic powder ratio (W / C) is the ratio of water to hydraulic powder in the hydraulic composition for spraying expressed as a mass percentage (mass%), and is calculated as (water / hydraulic powder) x 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.
[0017] The component (A) is a polyethylene oxide. From the viewpoint of reducing dust, the weight average molecular weight of the component (A) is preferably 200,000 or more, more preferably 300,000 or more, and from the viewpoint of the solubility of the component (A) in the hydraulic composition, it is preferably 10 million or less, more preferably 7 million or less, even more preferably 5 million or less, and even more preferably 1.5 million or less.
[0018] As the weight-average molecular weight of polyethylene oxide, in the case of a commercially available product, a value based on the product information (catalog, etc.) may be used. However, since the weight-average molecular weight of polyethylene oxide is correlated with the viscosity of an aqueous solution, and an approximate value can be obtained by the method described below, and calculation can be easily performed on site, it is more preferable to calculate it based on the aqueous solution viscosity. <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. JPEG2024067808000001.jpg42153
[0019] The component (A) may be an aqueous solution of polyethylene oxide or may be in solid form. The solid polyethylene oxide is preferably in the form of particles, more preferably in the form of powder or granules. Granules are generally particles having a relatively larger particle size than powder. The shape of the solid polyethylene oxide is not limited, and examples of the shape include spherical, plate-like, etc. The shape of the solid polyethylene oxide may be either regular or irregular.
[0020] From the viewpoint of reducing dust, the viscosity of a 2.0 mass % aqueous solution of component (A), i.e., the viscosity of a 2.0 mass % aqueous solution of component (A), at 25°C is preferably 10 mPa·s or more, more preferably 15 mPa·s or more, and even more preferably 20 mPa·s or more, and from the viewpoint of the solubility of component (A) in hydraulic compositions, the viscosity of a 0.5 mass % aqueous solution of component (A), i.e., the viscosity of a 0.5 mass % aqueous solution of component (A), at 25°C is preferably 410 mPa·s or less, more preferably 220 mPa·s or less, and even more preferably 90 mPa·s or less.
[0021] The viscosity of a 2.0% by mass aqueous solution of component (A) and a 0.5% by mass aqueous solution of component (A) are measured using a B-type viscometer at 25°C, with a No. 2 rotor, at 30 rpm, and after 1 minute. However, if the viscosity exceeds 1000 mPa s when measured with a No. 2 rotor, it is measured under the same conditions as above (25°C, 30 rpm, and after 1 minute) using a No. 3 rotor.
[0022] The hydraulic composition for spraying of the present invention contains, from the viewpoints of reducing dust and improving pumpability due to increased viscosity, preferably 0.0005% by mass or more of component (A) relative to the hydraulic powder in the hydraulic composition for spraying, more preferably 0.001% by mass or more, even more preferably 0.005% by mass or more, still more preferably 0.008% by mass or more, still more preferably 0.010% by mass or more, and preferably 1.0% by mass or less, more preferably 0.8% by mass or less, still more preferably 0.6% by mass or less, still more preferably 0.4% by mass or less, and still more preferably 0.2% by mass or less. It is preferable to add a relatively large amount of component (A) when the weight average molecular weight is small, and a relatively small amount when the weight average molecular weight is large.
[0023] <(B) component> The component (B) is a clay mineral. The clay mineral of the 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 suppressing adhesion to the nozzle. 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%.
[0024] In the spray hydraulic composition of the present invention, from the viewpoint of inhibiting adhesion to nozzles and reducing dust, the fine aggregate and component (B) in the spray hydraulic composition have a total adsorption amount of methylene blue measured in accordance with JIS Z2451:2019 per 100 g of the total content of the fine aggregate and component (B) of 0.37 mmol or more, preferably 0.38 mmol or more, more preferably 0.39 mmol or more, and preferably 1.5 mmol or less, more preferably 1.4 mmol or less, even more preferably 1.3 mmol or less, still more preferably 1.1 mmol or less, still more preferably 0.80 mmol or less, still more preferably 0.65 mmol or less, and still more preferably 0.55 mmol or less.
[0025] <Method for measuring the amount of methylene blue adsorbed> The methylene blue adsorption amount of the fine aggregate and component (B) is measured by the following method in accordance with the Japanese Industrial Standard (JIS Z2451:2019). <Reagents> Methylene blue (molecular weight 374) 10mmol / L aqueous solution 0.2% by weight aqueous solution of sodium pyrophosphate (Na4P2O7) <How to operate> Put about 20 g of fine aggregate and (B) component into a 100 mL screw tube, add 50 g of a 0.2 mass% aqueous solution of sodium pyrophosphate, and disperse this mixture for 30 minutes using an ultrasonic cleaner (ASU CLEANER, ASU-3, AS ONE Corporation). A 10 mmol / L methylene blue solution is dripped into the dispersed mixture, and each time a predetermined amount is dripped, the screw tube is capped and shaken by hand, and a part of the mixture is sucked up from the supernatant using a polyethylene dropper (polydropper) and dripped onto filter paper. The supernatant is dripped so that a spot of about 10 mm in diameter is formed on the filter paper. This operation is repeated until a halo is observed around the spot. Once a halo is observed, the titration is terminated when the width of the halo exceeds 2 mm. The amount of methylene blue adsorption (mmol) is calculated by multiplying the titration amount (L) by the concentration of the methylene blue aqueous solution (10 mmol / L) per 100 g of the mixture of fine aggregate and component (B).
[0026] The sprayable hydraulic composition of the present invention preferably has a methylene blue adsorption amount within the above range per 100 g of a mixture of the fine aggregate and component (B) before being mixed into the sprayable hydraulic composition. Therefore, the hydraulic composition for spraying of the present invention may be a hydraulic composition for spraying comprising a hydraulic powder, fine aggregate, (A) polyethylene oxide (component (A)), optionally a clay mineral (B) (component (B)), and water, wherein the fine aggregate and component (B) have a total adsorption amount of methylene blue of 0.37 mmol or more per 100 g of a mixture of the fine aggregate and component (B) measured in accordance with JIS Z2451:2019.
[0027] The clay mineral of component (B) is preferably a clay mineral having a swelling degree of 15 mL / 2 g or more and 50 mL / 2 g or less, from the viewpoint of suppressing adhesion of the spray hydraulic composition to the nozzle.
[0028] The swelling degree of the clay mineral of component (B) is 15 mL / 2g or more, preferably 20 mL / 2g or more, and 50 mL / 2g or less, preferably 45 mL / 2g or less, more preferably 40 mL / 2g or less, from the viewpoints of suppressing adhesion of the spray hydraulic composition to the nozzle and reducing dust. 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).
[0029] The hydraulic composition for spraying of the present invention contains component (B) in an amount of preferably 0.03% by mass or more, more preferably 0.04% by mass or more, even more preferably 0.05% by mass or more, and preferably 7% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, based on the hydraulic powder in the hydraulic composition for spraying, from the viewpoints of suppressing adhesion to nozzles and reducing dust.
[0030] The hydraulic composition for spraying of the present invention contains component (B) in an amount of preferably 0.010% by mass or more, more preferably 0.015% by mass or more, even more preferably 0.019% by mass or more, and preferably 2.70% by mass or less, more preferably 1.90% by mass or less, even more preferably 1.15% by mass or less, based on the fine aggregate in the hydraulic composition for spraying, from the viewpoints of inhibiting adhesion to nozzles and reducing dust.
[0031] The hydraulic composition for spraying of the present invention contains water. Examples of water include tap water, groundwater, lake water, and river water.
[0032] <Quick setting material> The spray hydraulic composition of the present invention may optionally contain a quick-setting admixture. The quick-setting admixture may be in any form, such as a powder, a liquid, or a combination of both. The quick-setting admixture may be, for example, one or more types of quick-setting admixture selected from cement mineral-based quick-setting admixtures and aluminum-based quick-setting admixtures.
[0033] The cement mineral-based quick-setting additive may be one or more selected from calcium aluminate, calcium sulfoaluminate, and calcium aluminate. The aluminum-based quick-setting additive 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 strength development, the quick-setting additive 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.
[0034] In the spray hydraulic composition of the present invention, an additive for the spray hydraulic composition (hereinafter referred to as the additive of the present invention), which is a mixture of the above-mentioned 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. From the viewpoint of strength development, 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.
[0035] In the additive of the present invention, the mass ratio of the content of the component (B) to the content of the quick-setting admixture, (quick-setting admixture) / (B), is, from the viewpoint of strength development, preferably 0.5 or more, more preferably 0.7 or more, even more preferably 1.0 or more, and preferably 90 or less, more preferably 70 or less, even more preferably 50 or less, still more preferably 40 or less, still more preferably 30 or less, and even more preferably 20 or less.
[0036] 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 viewpoint of strength expression, preferably 4 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 6 parts by mass or more, still more preferably 7 parts by mass or more, and preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 15 parts by mass or less of the quick-setting admixture relative to 100 parts by mass of the hydraulic powder contained in the hydraulic composition for spraying.
[0037] The hydraulic composition for spraying of the present invention may contain, as necessary, one or more of the following: high-performance water-reducing agents, high-performance AE water-reducing agents, water-reducing agents including AE water-reducing agents and fluidizing agents, expansive agents, hardening accelerators, hardening retarders, polymers for cement, foaming agents, waterproofing agents, rust inhibitors, shrinkage reducing agents, pigments, fibers, water repellents, efflorescence inhibitors, thickeners, etc. (However, excluding those corresponding to component (A)).
[0038] <Spraying method> The present invention provides a spraying method in which the sprayable hydraulic composition of the present invention is sprayed onto a target surface. The present invention also provides a spraying method, which comprises spraying onto a target surface a hydraulic composition for spraying, the hydraulic composition comprising a mixture of hydraulic powder, fine aggregate, component (A), and optionally component (B), wherein the fine aggregate and component (B) have a total adsorption amount of methylene blue of 0.37 mmol or more per 100 g of the total content of the fine aggregate and component (B), as measured in accordance with JIS Z2451:2019. In the spraying method of the present invention, the above-mentioned hydraulic composition for spraying may be mixed with a quick-setting admixture, and the hydraulic composition for spraying mixed with the quick-setting admixture may be sprayed onto an object. In the spraying method of the present invention, preferred embodiments of the hydraulic powder, fine aggregate, component (A), component (B), water and quick-setting admixture are the same as those described in the sprayable hydraulic composition of the present invention. The spraying method of the present invention can be applied to the embodiments described in the spray hydraulic composition of the present invention as appropriate. The preferred content in the spray 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.
[0039] The spraying method of the present invention is preferably a method in which the hydraulic composition for spraying and the quick-setting admixture are separately pumped and then mixed together, or a method in which water is added to the powder quick-setting admixture before the mixing to form a slurry, and the quick-setting admixture slurry is mixed and sprayed onto the hydraulic composition for spraying, and either a dry spraying method or a wet spraying method can be used. An example of the dry spraying method is a method in which hydraulic powder and aggregate are mixed, air pumped, water and the quick-setting admixture are mixed together, and the mixture is sprayed in a wet state. An example of the wet spraying method is a method in which hydraulic powder, aggregate, and water are mixed and kneaded, air pumped, mixed with the quick-setting admixture, and sprayed.
[0040] The spraying method of the present invention will be described in detail with reference to a specific example, but 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, aggregate including at least fine aggregate, component (A), optionally component (B), and water are mixed to produce a hydraulic composition for spraying. The hydraulic composition for spraying produced by mixing hydraulic powder, aggregate including at least fine aggregate, component (A), optionally component (B) and water 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 35 mass % or more, even more preferably 40 mass % or more, and preferably 80 mass % or less, more preferably 70 mass % or less, even more preferably 65 mass % or less, from the viewpoints of suppressing adhesion to nozzles, reducing dust, and furthermore, expressing strength to prevent the hydraulic composition for spraying from collapsing.
[0041] In the present invention, from the viewpoints of reducing dust and improving pumpability due to increased viscosity, the (A) component is mixed with the hydraulic powder in the spray hydraulic composition at a concentration of preferably 0.0005% by mass or more, more preferably 0.001% by mass or more, even more preferably 0.005% by mass or more, still more preferably 0.008% by mass or more, still more preferably 0.010% by mass or more, and preferably 1.0% by mass or less, more preferably 0.8% by mass or less, even more preferably 0.6% by mass or less, still more preferably 0.4% by mass or less, and still more preferably 0.2% by mass or less. It is preferable to mix a relatively large amount of component (A) when the weight average molecular weight is small, and a relatively small amount when the weight average molecular weight is large.
[0042] In the present invention, the hydraulic powder, aggregate, component (A), optional component (B), water, and other optional components can be mixed by a known method. For example, the hydraulic powder, water, and aggregate can be mixed simultaneously. For mixing these components, a mixing mixer such as a pan-type forced mixer, a two-shaft forced mixer, or a tilting mixer can be used.
[0043] In the present invention, a hydraulic composition for spraying can be produced by adding an arbitrary quick-setting admixture to a hydraulic composition obtained by mixing hydraulic powder, aggregate, component (A), optionally component (B) and water. The mixing of the hydraulic composition and the quick-setting admixture can be carried out, for example, by a general spraying method in which the hydraulic composition and the quick-setting admixture are compressed in air and mixed together.
[0044] In the present invention, from the viewpoint of inhibiting adhesion to the nozzle and reducing dust, the (B) component is mixed in an amount of preferably 0.03 parts by mass or more, more preferably 0.04 parts by mass or more, even more preferably 0.05 parts by mass or more, and preferably 7 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, per 100 parts by mass of the hydraulic powder in the hydraulic composition for spraying.
[0045] In the present invention, from the viewpoints of inhibiting adhesion to the nozzle and reducing dust, the (B) component is mixed with the fine aggregate in the sprayable hydraulic composition in an amount of preferably 0.010% by mass or more, more preferably 0.015% by mass or more, even more preferably 0.019% by mass or more, and preferably 2.70% by mass or less, more preferably 1.90% by mass or less, even more preferably 1.15% by mass or less.
[0046] 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 5 parts by mass or more, even more preferably 6 parts by mass or more, still more preferably 7 parts by mass or more, and preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 15 parts by mass or less, relative to 100 parts by mass of the hydraulic powder in the hydraulic composition, from the viewpoint of strength development.
[0047] In the spraying method of the present invention, the thus prepared hydraulic composition for spraying is sprayed onto an object. The spraying method of the present invention can be carried out by using conventional spraying equipment, which may be used as long as it can perform spraying without any problems, and for example, Arriba 280 (trade name) or the like manufactured by Arriba Corporation can be used for pumping the hydraulic composition, and Natomcrete (trade name) or the like manufactured by Chiyoda Seisakusho can be used for pumping the quick-setting admixture, and the two can be mixed to prepare a hydraulic composition for spraying, which can then be sprayed. EXAMPLES
[0048] The hydraulic compositions for spraying shown in Tables 1 and 2 were prepared and evaluated as follows. (1) Preparation of hydraulic composition for spray application <Components of hydraulic composition for spray application> The components of the spray hydraulic composition are as follows: <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. Fine aggregate: Mountain sand from Joyo City, Kyoto Prefecture Surface-dried specific gravity: 2.55 Fine aggregate: Mountain sand from Kimitsu City, Chiba Prefecture. Surface-dried specific gravity: 2.56.
[0049] <Component (A)> PEO: Polyethylene oxide, (product name) Alcox series, manufactured by Meisei Chemical Industry Co., Ltd. ·R-1000: Weight average molecular weight 250,000~450,000 ·E-30: Weight average molecular weight 400,000~550,000 ·E-45: Weight average molecular weight 600,000 to 1,000,000 ·E-60: Weight average molecular weight 1 million to 1.5 million ·E-75: Weight average molecular weight approximately 2 million ·E-240: Weight average molecular weight approximately 5 million ·E-300: Weight average molecular weight approximately 7 million In the table, the symbols shown in the column for type of PEO (polyethylene oxide) are product names, and the weight average molecular weights are catalog values.
[0050] The viscosity of a 2.0% by mass aqueous solution and a 0.5% by mass aqueous solution of component (A) was measured using a B-type viscometer at 25°C, No. 2 rotor, 30 rpm, and 1 minute. If the viscosity exceeded 1000 mPa s when measured with the No. 2 rotor, it was measured under the same conditions as above (25°C, 30 rpm, 1 minute) using the No. 3 rotor. In the case of a 2.0 mass% aqueous solution, when the value exceeded 4000 mPa·s, the upper limit of the measurement range of the No. 3 rotor, making measurement impossible, this is recorded as "over 4000" in Table 2. Furthermore, in this concentration range, the viscosity of an aqueous solution of polyethylene oxide tends to decrease as the concentration decreases, so if the viscosity of a 2.0% by mass aqueous solution is 410 mPa s or less, the viscosity of a 0.5% by mass aqueous solution is determined to be 410 mPa s or less, and the viscosity of the 0.5% by mass aqueous solution was not measured. In other words, polyethylene oxide with a viscosity of 410 mPa s or less in a 2.0% by mass aqueous solution satisfies the requirement that the viscosity of a 0.5% by mass aqueous solution be 410 mPa s or less. The different viscosities of the 2.0 mass % aqueous solutions of E-45 are due to the different lots of E-45.
[0051] <(B) Component: Clay minerals> Bentonite A: Bentonite, Kunigel GS, manufactured by Kunimine Kogyo Co., Ltd., swelling degree 33 mL / 2 g Bentonite B: Bentonite, TB-250, manufactured by Tachibana Material Co., Ltd., swelling degree 14mL / 2g
[0052] 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).
[0053] (2) Measurement of methylene blue adsorption amount The methylene blue adsorption amount of the fine aggregate and component (B) was measured according to the following method in accordance with the Japanese Industrial Standard (JIS Z2451:2019). 1.87 g of methylene blue (molecular weight 374, Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 500 mL of ion-exchanged water to prepare a 10 mmol / L aqueous solution of methylene blue. In addition, 1.68 g of sodium pyrophosphate decahydrate (molecular weight 446, Sigma-Aldrich) was dissolved in 500 mL of ion-exchanged water to prepare a 0.2 mass% aqueous solution of sodium pyrophosphate. <Reagents> Methylene blue (molecular weight 374) 10mmol / L aqueous solution 0.2% by weight aqueous solution of sodium pyrophosphate (Na4P2O7) <How to operate> Approximately 20 g of fine aggregate and component (B) were placed in a 100 mL screw tube, and 50 g of a 0.2 mass% aqueous solution of sodium pyrophosphate was added to the mixture. This mixture was dispersed for 30 minutes using an ultrasonic cleaner (ASU CLEANER, ASU-3, AS ONE Corporation). A 10 mmol / L methylene blue solution was dropped into the dispersed mixture, and after each drop, the screw tube was capped and shaken by hand, and a part of the mixture was sucked up from the supernatant using a polyethylene dropper (polydropper) and dropped onto a filter paper. The supernatant was dropped to the extent that a spot of about 10 mm in diameter was formed on the filter paper. This operation was repeated until a halo was observed around the spot. When a halo was observed, the titration was terminated when the width of the halo exceeded 2 mm. Then, based on the masses of the fine aggregate and component (B) and the total amount of the 10 mmol / L methylene blue solution added up to the end point, the total amount of methylene blue adsorption per 100 g of the total content of the fine aggregate and component (B) was calculated. Specifically, the product of the titration amount (L) and the concentration of the methylene blue aqueous solution (10 mmol / L) was converted to a value per 100 g of the mixture of fine aggregate and component (B) to calculate the total methylene blue adsorption amount (mmol).
[0054] A mortar mixer as specified in "JIS R 5201 Physical Test Methods for Cement" was used to prepare the sprayable hydraulic composition. 400 g of hydraulic powder, 1,054 g of fine aggregate, polyethylene oxide and clay mineral in the amounts shown in Tables 1 and 2 were added to the mixing bowl of a mortar mixer and stirred at low speed for 10 seconds. Then, 240 g of water was added and stirred for an additional 2 minutes to obtain a hydraulic composition for spraying. In Comparative Examples 1-6 and 1-7 and Examples 1-10 and 1-11, 1.0 part by weight of an AE water reducing agent (Mitei 1000S manufactured by Kao Corporation) was added to water in advance for 100 parts by weight of cement, and 168 g of water was used.
[0055] (3) Evaluation (3-1) Evaluation of 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 dust-covered kitchen paper (filter 6) was visually observed and the amount of dust was evaluated based on the following evaluation criteria. The higher the value, the greater the reduction in the amount of dust. [Evaluation Criteria] 1: The entire area is clearly colored gray. 2: The whole or part is colored light gray. 3: No coloring at all
[0056] 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. * It can be said that the higher the value, the more the amount of dust is reduced. For example, the L value of a spray hydraulic composition that does not contain components (A) and (B) is * The value is 74.8, so if it is 80.0 or more, it can be judged that the amount of dust is reduced. Furthermore, the visual observation results of the kitchen paper are summarized as follows: L * A value of 84.0 or more, and more preferably 86.0 or more, can be considered to indicate that the amount of dust has been further reduced.
[0057] (3-2) Evaluation of nozzle adhesion rate In the evaluation of the amount of dust (3-1) above, after the spraying operation of the spray hydraulic composition was performed, the mass of the spray hydraulic composition sprayed into the box 4 was measured, and the nozzle adhesion rate was calculated based on the following formula (1). It can be said that the lower the nozzle adhesion rate, the more the adhesion to pipes and nozzles is suppressed. For example, the nozzle adhesion rate of the spray hydraulic composition not containing the components (A) and (B) is 13.1% by mass, and it can be determined that adhesion is suppressed when the nozzle adhesion rate is less than 13.0% by mass. Nozzle adhesion rate (mass%)=100×[(amount of spray hydraulic composition added)−(mass of spray hydraulic composition sprayed into box 4)] / (amount of spray hydraulic composition added) (1)
[0058] [Table 1]
[0059] [Table 2]
[0060] In Tables 1 and 2, the amounts of components (A) and (B) added are ※1 (Cement x %), (B) component added amount ※2 (Fine aggregate x %), W / C ratio ※3 , MB adsorption amount ※4 indicates the following values, respectively. *1: The amount of component (A) or component (B) added (cement × %) indicates the mass percentage of component (A) or component (B) relative to cement (C) (cement × mass %). *2: The amount of component (B) added (fine aggregate × %) indicates the mass percentage of component (B) to the fine aggregate (fine aggregate × mass %). *3: The W / C ratio indicates the ratio of water (W) to cement (C) in the sprayable hydraulic composition as a mass percentage (mass%). *4: The MB adsorption amount is the total amount of methylene blue adsorption of fine aggregate and component (B) per 100 g of the total mixture of fine aggregate and component (B). [Explanation of symbols]
[0061] 1. Powder and granular material transport device 3 wood board 4 boxes 4c Lid 6 Filters
Claims
1. A hydraulic composition for spraying comprising hydraulic powder, fine aggregate, (A) polyethylene oxide (hereinafter referred to as component (A)), optionally (B) a clay mineral (hereinafter referred to as component (B)), and water, wherein the fine aggregate and component (B) have a total adsorption amount of methylene blue of 0.37 mmol or more per 100 g of the total content of the fine aggregate and component (B), as measured in accordance with JIS Z2451:2019.
2. 2. The hydraulic composition for spraying according to claim 1, wherein the component (A) is contained in an amount of 0.001% by mass or more and 0.4% by mass or less based on the hydraulic powder.
3. 3. The hydraulic composition for spraying according to claim 1, wherein component (A) has a viscosity of 10 mPa·s or more in a 2.0% by mass aqueous solution at 25°C and a viscosity of 410 mPa·s or less in a 0.5% by mass aqueous solution at 25°C.
4. 3. The hydraulic composition for spraying according to claim 1, wherein the swelling degree of component (B) is 15 mL / 2 g or more and 50 mL / 2 g or less.
5. 3. The hydraulic composition for spraying according to claim 1, wherein the component (B) is contained in an amount of 0.03% by mass to 7% by mass based on the hydraulic powder.
6. 3. The sprayable hydraulic composition according to claim 1, wherein the component (B) is contained in an amount of 0.010% by mass to 1.90% by mass relative to the fine aggregate.
7. 3. The hydraulic composition for spraying according to claim 1, wherein the ratio of the water content to the hydraulic powder content contained in the hydraulic composition for spraying (water / hydraulic powder) is 30% by mass or more and 70% by mass or less.
8. A spraying method, comprising spraying the sprayable hydraulic composition according to claim 1 or 2 onto a target surface.