Methods for creating sculptural objects

Abstract

To provide a molding method of a molded object, which can prevent blockage due to curing of a hydraulic composition in an additive manufacturing device and ensure self-reliance until the hydraulic composition is cured.SOLUTION: A molding method of a molded object using a hydraulic composition for an additive manufacturing device includes: a cement composition preparing step of mixing cement with a ferrite phase ratio of 4.0 mass% or more as a value calculated by Borg's formula and water to obtain a cement composition 8; an accelerating agent supplying step of supplying an accelerating agent 9 in an amount of 0.2 to 5.0 pts.mass per 100 pts.mass of cement to the cement composition 8 in a nozzle 3 of an additive manufacturing device 1, immediately before extruding the cement composition 8; an extruding step of extruding the hydraulic composition 11 for the additive manufacturing device from the additive manufacturing device 1; a molding step of molding a molded object by using the extruded hydraulic composition 11 for the additive manufacturing device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for creating molded objects. [Background technology]

[0002] In recent years, a technique has become widespread in which a photocurable resin is extruded from a nozzle onto the top surface of a 3D printer's stacking bed to form an uncured layered body pre-designed as a two-dimensional shape. This uncured layered body is then cured by light irradiation to obtain a cured layered body. Subsequently, the same operation is repeated on top of this cured layered body to build and cure each layer one by one, ultimately obtaining a laminated object with a pre-designed desired three-dimensional shape (for example, one with an intricate three-dimensional shape). This technique is called additive manufacturing.

[0003] Additive manufacturing technologies using various materials other than photocurable resins (e.g., cement) have also been developed. As a cement slurry dispensing device useful for manufacturing molded objects, for example, Patent Document 1 describes a cement slurry dispensing device having hydraulic properties, comprising: a main body of the device; a first container detachably provided to the main body of the device and containing a cement-containing liquid containing cement, water, and an inorganic acid; a second container detachably provided to the main body of the device and containing an alkaline solution containing an ionic emulsion-type thickener; a mixer for mixing the cement-containing liquid and the alkaline solution to obtain the cement slurry; a first transfer means for transferring the cement-containing liquid in the first container to the mixer; a second transfer means for transferring the alkaline solution in the second container to the mixer; and a discharge port for dispensing the cement slurry from the mixer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-24979 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] When manufacturing molded objects from cement compositions using an extrusion-type additive manufacturing apparatus, molds and other structures are usually not installed. Therefore, the cement composition is required to have self-supporting properties (the ability to maintain its shape even when a new layer of cement composition is added on top of the extruded cement composition) from the time it is extruded from the nozzle of the additive manufacturing apparatus until it hardens. A method is known in which a rapid-setting agent is added to a cement composition with relatively good fluidity in order to maintain its self-supporting properties until the cement composition hardens. However, cement compositions with excellent rapid-hardening properties are difficult to ensure fluidity in the additive manufacturing equipment before being extruded from the nozzle, and when the time required for molding is long, there is a problem that blockage may occur in the additive manufacturing equipment (for example, in the pipeline for pumping the cement composition in the additive manufacturing equipment). The object of the present invention is to provide a method for fabricating molded objects that prevents blockage due to hardening of the hydraulic composition within the additive manufacturing apparatus and ensures self-supporting stability until the hydraulic composition hardens. [Means for solving the problem]

[0006] As a result of diligent research to solve the above problems, the inventors of the present invention have found that the above objectives can be achieved by a method for manufacturing molded objects that includes the steps of: mixing cement having a ferrite phase content of 4.0% by mass or more with water to obtain a cement composition; supplying an amount of rapid setting agent to the cement composition in an amount of 0.2 to 5.0 parts by mass per 100 parts by mass of cement immediately before extruding the cement composition to obtain a hydraulic composition; extruding the hydraulic composition from an additive manufacturing apparatus; and manufacturing a molded object using the extruded hydraulic composition. Based on this finding, the inventors of the present invention have completed the present invention. In other words, the present invention provides the following [1] to [7]. [1] A method for forming an object using a hydraulic composition for additive manufacturing equipment, comprising: a cement composition preparation step of mixing cement having a ferrite phase ratio of 4.0% by mass or more as calculated by Borg's formula with water to obtain a cement composition; a rapid-setting agent supply step of supplying a rapid-setting agent in an amount of 0.2 to 5.0 parts by mass per 100 parts by mass of cement to the cement composition in the nozzle of the additive manufacturing equipment immediately before extruding the cement composition to obtain the hydraulic composition for additive manufacturing equipment; an extrusion step of extruding the hydraulic composition for additive manufacturing equipment from the additive manufacturing equipment; and a forming step of forming the object using the extruded hydraulic composition for additive manufacturing equipment.

[0007] [2] The method for forming an object according to [1], wherein in the cement composition preparation step, an amount of inorganic powder (excluding cement) in the form of 2 to 150 parts by mass is mixed with 100 parts by mass of cement. [3] The method for fabricating an object according to [2] above, wherein the inorganic powder is one or more selected from silica fume, blast furnace slag powder, fly ash, limestone powder, and silica powder. [4] The method for forming a molded object according to any one of [1] to [3], wherein in the cement composition preparation step, an amount of fiber equal to 0.1 to 4.0 parts by mass is further mixed with 100 parts by mass of cement. [5] A method for forming a molded object according to any one of the above [1] to [4], wherein the thickening agent is supplied to the cement composition in the nozzle so that the thickening agent ultimately becomes a material constituting the hydraulic composition for the additive manufacturing apparatus. [6] The method for forming a molded object according to [5], wherein the amount of the thickening agent is 0.01 to 2.0 parts by mass per 100 parts by mass of the cement. [7] The method for forming a molded object according to [5] or [6], wherein the thickening agent is one or more thickening agents selected from cellulose-based, acrylic-based, and glycol-based. [Effects of the Invention]

[0008] According to the method for forming a shaped object of the present invention, it is possible to prevent blockage due to the curing of the hydraulic composition in the additive manufacturing apparatus and ensure the self-supportability until the hydraulic composition cures.

Brief Description of the Drawings

[0009] [Figure 1] It is a figure which shows an example of a part of an additive manufacturing apparatus used by the shaping | molding method of the shaped object of this invention, Comprising: It is sectional drawing which shows the state which cut | disconnected the part containing the nozzle of the said additive manufacturing apparatus in the perpendicular direction.

Embodiments for Carrying Out the Invention

[0010] The method for forming a shaped object of the present invention is a method for forming a shaped object using a hydraulic composition for an additive manufacturing apparatus (hereinafter, also simply referred to as "hydraulic composition"), and the ratio of the ferrite phase (4CaO·Al2O3·Fe2O3; also referred to as "C4AF") is 4.0% by mass or more as a value calculated by the Bogue formula. A cement composition preparation step of mixing cement and water to obtain a cement composition, and immediately before extruding the cement composition, a setting accelerator in an amount of 0.2 to 5.0 parts by mass with respect to 100 parts by mass of cement is supplied to the cement composition in the nozzle of the additive manufacturing apparatus to obtain a hydraulic composition for the additive manufacturing apparatus. A setting accelerator supply step, an extrusion step of extruding the hydraulic composition for the additive manufacturing apparatus from the additive manufacturing apparatus, and a shaping step of shaping the shaped object using the extruded hydraulic composition for the additive manufacturing apparatus. Hereinafter, each step will be described in detail.

[0011] [Cement Composition Preparation Step] This step is a step of mixing cement in which the ratio of the ferrite phase is 4.0% by mass or more as a value calculated by the Bogue formula and water to obtain a cement composition. As the cement, when forming a shaped object using an additive manufacturing apparatus, a cement having physical properties that can be used as a material for the shaped object can be used. Examples of such cement include ordinary Portland cement, early-strength Portland cement, medium-heat Portland cement, low-heat Portland cement, white Portland cement, super-fast-hardening cement, ultra-early-strength Portland cement, blast furnace cement, fly ash cement, alumina cement, eco-cement, and the like. These may be used alone or in combination of two or more.

[0012] The proportion of the ferrite phase in the cement is 4.0% by mass or more, preferably 5,0% by mass or more, more preferably 5.5% by mass or more, still more preferably 6.0% by mass or more, still more preferably 8.0% by mass or more, and particularly preferably 9.5% by mass or more. When the above proportion is less than 4.0% by mass, the self-supporting property of the hydraulic composition decreases. In addition, clogging due to the hardening of the hydraulic composition in the nozzle is likely to occur. Further, from the viewpoint of ease of manufacture of the cement and the like, the above proportion is preferably 25.0% by mass or less, more preferably 20.0% by mass or less, and particularly preferably 15.0% by mass or less. The proportion of belite (2CaO·SiO2; also referred to as C2S) in the cement is preferably 8.0 to 75.0% by mass, more preferably 9.0 to 70.0% by mass, and particularly preferably 10.0 to 65.0% by mass. If the above proportion is 8.0% by mass or more, the strength development property of the hydraulic composition is further improved. If the above proportion is 75.0% by mass or less, the self-supporting property of the hydraulic composition is further improved.

[0013] The proportion of alite (3CaO·SiO2; also referred to as C3S) in the cement is preferably 15.0 to 85.0% by mass, more preferably 20.0 to 80.0% by mass, and particularly preferably 25.0 to 75.0% by mass from the viewpoints of strength development property and fluidity of the hydraulic composition. The proportion of the aluminate phase (3CaO·Al2O3; also called C3A) in the cement is preferably 0.5 to 12.0% by mass, more preferably 1.0 to 10.0% by mass, and particularly preferably 1.5 to 9.0% by mass. If the above proportion is 1.0% by mass or more, the strength development of the hydraulic composition is further improved. If the above proportion is 12.0% by mass or less, the heat of hydration of the hydraulic composition can be further reduced.

[0014] The proportions of alite, belite, aluminate, and ferrite phases in cement can be calculated using the following Borg equations (1) to (4), based on the results of chemical analysis of the cement. (1) Alite (C3S) = (4.07 × CaO) - (7.60 × SiO2) - (6.72 × Al2O3) - (1.43 × Fe2O3) - (2.85 × SO3) (2) B-Lite (C2S) = (2.87 × SiO2) - (0.754 × C3S) (3) Aluminate phase (C3A) = (2.65 × Al2O3) - (1.69 × Fe2O3) (4) Ferrite phase (C4AF) = (3.04 × Fe2O3)

[0015] The type of water used is not particularly limited and includes tap water, and recycled water as defined in "JIS A 5308:2019 (Ready-Mixed Concrete)". The amount of water is determined so that the water-cement ratio is preferably 25-50%, more preferably 30-45%, and particularly preferably 35-42%. If the above ratio is 25% or higher, the compressive strength of the molded object can be further increased. If the above ratio is 50% or lower, the molded object can be made less prone to deformation during the process of laminating the hydraulic composition. The water-cement ratio is the mass ratio of water to cement (water / cement) expressed as a percentage (%).

[0016] When preparing a cement composition, the means of mixing the materials are not particularly limited, and a mixer commonly used in mixing mortar and concrete can be used. Specifically, these include vertical mixers, horizontal mixers, Nauter mixers, tilting drum mixers, forced mixers, and twin-screw mixers. Examples of vertical mixers include the "Hobart Mixer" manufactured by Hobart and the "Henschel Mixer" manufactured by Henschel. Examples of horizontal mixers include the "Redige Mixer" manufactured by Redige GmbH.

[0017] In this process, inorganic powders other than cement may be mixed in to further prevent blockage due to hardening of the hydraulic composition within the additive manufacturing apparatus and to further improve the self-supporting properties of the molded object made from the hydraulic composition. Examples of the inorganic powders mentioned above include silica fume, blast furnace slag powder, fly ash, limestone powder, and silica powder. These may be used individually or in combination of two or more. In particular, from the viewpoint of further improving the self-supporting properties of molded objects made from hydraulic compositions and further preventing blockage due to hardening of cement compositions or hydraulic compositions within additive manufacturing equipment, it is preferable to use both limestone fine powder and silica fume.

[0018] The amount of the inorganic powder (or the total amount if there are two or more types of inorganic powder) is preferably 2 to 150 parts by mass, more preferably 3 to 120 parts by mass, per 100 parts by mass of cement, from the viewpoint of further preventing blockage due to hardening of the cement composition or hydraulic composition in the additive manufacturing apparatus. When the inorganic powder (hereinafter sometimes abbreviated as "inorganic powder") is silica fume, the amount of silica fume is preferably 2 to 30 parts by mass, more preferably 8 to 28 parts by mass, and particularly preferably 12 to 25 parts by mass, per 100 parts by mass of cement. If the above amount is 2 parts by mass or more, the fluidity of the cement composition or hydraulic composition is further improved, and clogging in the additive manufacturing apparatus can be further prevented. If the above amount is 30 parts by mass or less, the strength development of the hydraulic composition is further improved. When the inorganic powder is blast furnace slag fine powder, the amount of blast furnace slag fine powder is preferably 2 to 40 parts by mass, more preferably 8 to 38 parts by mass, and particularly preferably 12 to 35 parts by mass, per 100 parts by mass of cement. If the above amount is 2 parts by mass or more, the fluidity of the cement composition or hydraulic composition is further improved, and clogging in the additive manufacturing apparatus can be further prevented. If the above amount is 40 parts by mass or less, the shrinkage of the molded product after hardening can be reduced.

[0019] When the inorganic powder is fly ash, the amount of fly ash is preferably 2 to 40 parts by mass, more preferably 8 to 38 parts by mass, and particularly preferably 12 to 35 parts by mass, per 100 parts by mass of cement. If the amount is 2 parts by mass or more, the fluidity of the cement composition or hydraulic composition is further improved, and clogging in the additive manufacturing apparatus can be better prevented. If the amount is 40 parts by mass or less, the initial strength of the molded object can be further increased. When the inorganic powder is limestone fine powder, the amount of limestone fine powder is preferably 2 to 150 parts by mass, more preferably 8 to 130 parts by mass, and particularly preferably 40 to 110 parts by mass, per 100 parts by mass of cement. If the above amount is 2 parts by mass or more, the self-supporting properties of the hydraulic composition can be further improved. If the above amount is 150 parts by mass or less, the fluidity of the cement composition or hydraulic composition can be further improved, and clogging in the additive manufacturing apparatus can be further prevented. When the inorganic powder is silica fine powder, the amount of the silica fine powder is preferably 2 to 40 parts by mass, more preferably 8 to 38 parts by mass, and particularly preferably 12 to 35 parts by mass with respect to 100 parts by mass of the cement. If the above amount is 2 parts by mass or more, the self-supporting property of the hydraulic composition is further improved. If the above amount is 40 parts by mass or less, the fluidity of the cement composition or the hydraulic composition is further improved, and blockage in the additive manufacturing apparatus can be further prevented.

[0020] The Blaine specific surface area of the blast furnace slag fine powder, fly ash, and limestone fine powder is preferably 2,500 to 10,000 cm 2 / g, more preferably 3,000 to 9,000 cm 2 / g, still more preferably 3,100 to 8,500 cm 2 / g, and particularly preferably 3,200 to 8,000 cm 2 / g. If the Blaine specific surface area is 2,500 cm 2 / g or more, the strength development property of the hydraulic composition is further improved. If the Blaine specific surface area is 10,000 cm 2 / g or less, the fluidity of the cement composition or the hydraulic composition is further improved, and blockage in the additive manufacturing apparatus can be further prevented. The BET specific surface area of the silica fume and the silica fine powder is preferably 5 to 40 m 2 / g, more preferably 10 to 35 m 2 / g, still more preferably 15 to 30 m 2 / g, and particularly preferably 18 to 25 m 2 / g. If the BET specific surface area is 5 m 2 / g or more, the strength development property of the hydraulic composition is further improved. If the BET specific surface area is 40 m 2 / g or less, the fluidity of the cement composition or the hydraulic composition is further improved, and blockage in the additive manufacturing apparatus can be further prevented.

[0021] In this step, from the viewpoints of further improving the self-supporting property of the hydraulic composition and further preventing blockage due to the curing of the cement composition or the hydraulic composition in the additive manufacturing apparatus, fibers may be further mixed. Examples of fibers include glass fibers, metal fibers, organic fibers, and carbon fibers. These may be used individually or in combination of two or more types. Among these, glass fibers are preferred from the viewpoint of economy and compatibility with cement. The shape and dimensions of the fibers are preferably such that the length is 0.1 mm or more and the aspect ratio (length / diameter) is 20 or more, more preferably the length is 1 to 30 mm and the aspect ratio (length / diameter) is 20 to 1,000, even more preferably the length is 2 to 20 mm and the aspect ratio (length / diameter) is 50 to 500, and even more preferably the length is 5 to 15 mm and the aspect ratio (length / diameter) is 100 to 400. If the fiber length is 0.1 mm or more, the self-supporting properties of the hydraulic composition can be further improved. Furthermore, the strength (e.g., flexural strength) of the molded object after curing can be increased. If the fiber length is 30 mm or less, blockage within the additive manufacturing equipment can be more effectively prevented. Additionally, fiber ball formation during mixing becomes less likely. Furthermore, if the aspect ratio (length / diameter) of the fibers is 20 or greater, the number of fibers per unit volume increases, further improving the self-supporting properties of the hydraulic composition. Additionally, the strength of the molded object after curing (e.g., flexural strength) can be further improved. Moreover, if the ratio is 1,000 or less, the strength of the fibers themselves becomes sufficient, making them less prone to breakage under tension.

[0022] The amount of fibers is preferably 0.1 to 4.0 parts by mass, more preferably 0.3 to 3.5 parts by mass, and particularly preferably 0.8 to 2.5 parts by mass, per 100 parts by mass of cement. If the amount is 0.1 parts by mass or more, the self-supporting properties of the hydraulic composition can be further improved. In addition, the strength (e.g., flexural strength) of the molded product after hardening can be further increased. If the amount is 4.0 parts by mass or less, the fluidity of the cement composition or hydraulic composition can be further improved, and clogging in the additive manufacturing equipment can be further prevented.

[0023] [Rapid setting agent mixing process] This process is performed after the cement composition preparation process, and immediately before the cement composition obtained in the cement composition preparation process is extruded, a rapid-setting agent is supplied to the cement composition in the nozzle of the additive manufacturing apparatus in an amount of 0.2 to 5.0 parts by mass per 100 parts by mass of cement to obtain a hydraulic composition (hydraulic composition for additive manufacturing apparatus). "Immediately before extruding the cement composition" means the moment immediately before the hydraulic composition for additive manufacturing (a mixture of cement composition and a quick-setting agent) is extruded from the tip of the nozzle of the additive manufacturing equipment (for example, within 7 seconds). The above supply timing varies depending on the nozzle diameter and discharge speed (speed at which the hydraulic composition is extruded) of the additive manufacturing apparatus, but for example, it is performed at a time, preferably 0.5 to 30 seconds, more preferably 1 to 15 seconds, even more preferably 1.5 to 10 seconds, and particularly preferably 2 to 5 seconds, before the hydraulic composition is extruded from the nozzle. If the supply is performed at least 0.5 seconds before the hydraulic composition is extruded from the nozzle, the supplied quick-setting agent and cement composition will be mixed more uniformly within the nozzle's flow path as they are extruded, thereby further improving the self-supporting properties of the hydraulic composition. If the supply is performed within 30 seconds of the hydraulic composition being extruded from the nozzle, clogging due to hardening of the hydraulic composition within the nozzle can be more effectively prevented. Furthermore, from the viewpoint of uniformly mixing the supplied quick-setting agent and cement composition, mixing means such as an in-line mixer or stirring blades may be provided inside the nozzle.

[0024] Examples of rapid setting agents include aluminum-based rapid setting agents such as aluminum sulfate and aluminum silicate, aluminate-based rapid setting agents, and calcium aluminate-based rapid setting agents. The amount of the quick-setting agent is 0.2 to 5.0 parts by mass, preferably 0.8 to 4.5 parts by mass, more preferably 1.0 to 4.0 parts by mass, even more preferably 1.2 to 3.0 parts by mass, and particularly preferably 1.5 to 2.0 parts by mass, per 100 parts by mass of cement. If the amount is less than 0.2 parts by mass, the self-supporting ability of the hydraulic composition will decrease. If the amount exceeds 5.0 parts by mass, the hydraulic composition will harden in the nozzle of the additive manufacturing apparatus, making blockage more likely. In addition, the self-supporting ability of the hydraulic composition may decrease.

[0025] [Extrusion process] This step is performed after the rapid-setting agent mixing step, and involves extruding the hydraulic composition for additive manufacturing obtained in the rapid-setting agent mixing step from the additive manufacturing apparatus. [Modeling process] This process is performed after the extrusion process and involves forming an object using the hydraulic composition for additive manufacturing equipment that was extruded in the extrusion process.

[0026] In the present invention, a thickener may be supplied to the cement composition in the nozzle so that the thickener ultimately becomes a material constituting the hydraulic composition for the additive manufacturing apparatus. By supplying a thickener to the cement composition, the voids on the surface of the molded object formed by the hardening of the hydraulic composition can be reduced, thereby improving the appearance of the molded object. The thickening agent may be supplied before the rapid-setting agent is supplied to the cement composition, or it may be supplied at the same time as the rapid-setting agent is supplied to the cement composition (in other words, the cement composition, rapid-setting agent, and thickening agent may be supplied simultaneously). In particular, from the viewpoint of further reducing the voids on the surface of the molded object formed by the hardening of the hydraulic composition and further improving the appearance of the molded object, it is preferable to supply a thickening agent before supplying a rapid-setting agent to the cement composition. More specifically, in the rapid-setting agent supply step, a method can be used in which a thickening agent is supplied to the cement composition to obtain a mixture, and then a rapid-setting agent is supplied to the mixture to obtain a hydraulic composition. By supplying a thickening agent in the rapid-setting agent supply step, blockage in the additive manufacturing apparatus can be prevented. Furthermore, from the viewpoint of further preventing blockage due to hardening of the cement composition or hydraulic composition within the additive manufacturing apparatus, it is preferable that the thickening agent be supplied to the cement composition at a time of 0.5 to 30 seconds, more preferably 1 to 15 seconds, and particularly preferably 2 to 10 seconds, before the fastening agent is supplied to the cement composition.

[0027] Examples of thickeners include: (1) cellulose-based thickeners such as cellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, and their derivatives (e.g., hydroxypropyl methyl ether); (2) acrylic-based thickeners such as polyacrylamide, polyacrylic acid esters, and polyacrylate salts (e.g., sodium polyacrylate); (3) glycol-based thickeners such as polyoxyethylene polyoxypropylene glycol; and (4) polysaccharides derived from natural materials such as guar gum, xanthan gum, deutan gum, gellan gum, carrageenan, locust bean gum, tara gum, pectin, gellan gum, alginate salts (e.g., sodium alginate), and their derivatives. These may be used individually or in combination of two or more. Furthermore, the type of thickener may be appropriately selected depending on the purpose. For example, from the viewpoint of further reducing the voids on the surface of the molded object formed by the hardening of the hydraulic composition and improving the appearance of the molded object, a cellulose-based thickener is preferred, and hydroxypropyl methylcellulose is more preferred. Also, when a naphthalene sulfonic acid-based thickener is used as the water-reducing agent, phenomena such as decreased fluidity, abnormal increase in air content, and delayed setting time may occur, so in such cases, it is preferable to use an acrylic-based thickener. In addition, when it is desirable to increase viscosity from the viewpoint of pumpability, but stress during flow should be suppressed (to prevent clogging), it is preferable to use a glycol-based thickener.

[0028] The amount of the thickening agent is preferably 0.01 to 2.0 parts by mass, more preferably 0.03 to 1.8 parts by mass, even more preferably 0.09 to 1.1 parts by mass, and particularly preferably 0.10 to 1.0 parts by mass, per 100 parts by mass of the cement, from the viewpoint of further reducing the voids on the surface of the molded object formed by the hardening of the hydraulic composition and further improving the appearance of the molded object. Furthermore, when the thickening agent is a liquid, the viscosity of the thickening agent is preferably 8,000 to 40,000 mPa·s, more preferably 10,000 to 38,000 Pa·s, and particularly preferably 12,000 to 20,000 Pa·s.

[0029] The cement composition preferably includes fine aggregate, from the viewpoint of reducing the amount of heat generated during the preparation of the cement composition. Examples of fine aggregates include silica sand, river sand, land sand, sea sand, and crushed sand (for example, crushed sand made from limestone). The amount of fine aggregate per 100 parts by mass of cement is preferably 5 to 1,000 parts by mass, more preferably 8 to 900 parts by mass, even more preferably 20 to 500 parts by mass, and particularly preferably 50 to 200 parts by mass. If the amount is 5 parts by mass or more, the effect of reducing the amount of heat generated during the preparation of the cement composition becomes greater. If the amount is 1,000 parts by mass or less, the compressive strength of the composition of the present invention after hardening becomes greater. A preferred example of fine aggregate is one containing granular material with a particle size in the range of 0.1 to 0.3 mm in proportion to 50% by mass or more (for example, silica sand No. 7, silica sand No. 6).

[0030] The cement composition may optionally contain other materials. Other examples of materials include cement dispersants, setting retarders, setting accelerators, and coarse aggregates. Examples of cement dispersants include polycarboxylic acid-based water-reducing agents. Examples of setting retarders include citric acid and succinic acid. Examples of setting accelerators include sodium sulfate and sodium thiosulfate. Examples of coarse aggregates include river gravel, land gravel, sea gravel, and crushed stone (for example, crushed stone made of limestone). When the composition of the present invention contains coarse aggregate, it is mainly used for forming relatively large construction structures with a simple structure. Fine aggregates and other optionally blendable materials are typically mixed with cement and water during the cement composition preparation process.

[0031] In the method for fabricating the molded object of the present invention, an example of a specific method for supplying the rapid-setting agent and the thickening agent will be described below with reference to Figure 1. In the cement composition preparation process, the cement composition 8 prepared by the mixing means described above is, for example, fed into a material input hopper (not shown) of the additive manufacturing apparatus 1, and then transferred from the material input hopper through a supply pipe 2 to the nozzle 3 of the additive manufacturing apparatus 1 using a squeeze pump or an in-line mixer. The supply pipe 2 is not particularly limited and can be, for example, a hose (with flexibility), a PVC pipe, etc. The cement composition 8 is supplied with a quick-setting agent 9 in the nozzle 3. As a result, the resulting hydraulic composition 11 for additive manufacturing is extruded from the additive manufacturing apparatus 1. The first supply channel 6 for supplying the quick-setting agent 9 is located downstream of the connection between the supply pipe 2 and the nozzle 3 in the direction in which the cement composition 8 is pushed out (discharged), and is in communication with the flow path of the nozzle 3 for pushing the cement composition 8 to the outside. The second supply channel 7 for supplying the thickener 10 is located upstream of the connection between the first supply channel 6 and the nozzle 3 in the direction in which the cement composition 8 is pushed out (discharged) (between the connection between the supply pipe 2 and the nozzle 3 and the connection between the first supply channel 6 and the nozzle 3), and is in communication with the flow path of the nozzle 3 for pushing the cement composition 8 to the outside. By configuring the components of the additive manufacturing apparatus 1 in this way, the thickener can be supplied to the cement composition before it is supplied to the quick-setting agent. Specifically, immediately before the cement composition 8 is extruded, the thickener 10 contained in the second container 5 is supplied to and mixed (merged) with the cement composition 8 through the second supply channel 7. Then, the quick-setting agent 9 contained in the first container 4 is supplied to and mixed (merged) with the cement composition 8 through the first supply channel 6 to prepare a hydraulic composition (a hydraulic composition 11 for additive manufacturing equipment, which is a mixture of the cement composition, quick-setting agent, and thickener). In Figure 1, the quick-setting agent and thickener are liquids, but the quick-setting agent and thickener used in the present invention are not limited to liquids.

[0032] Next, based on the molding data read by the control computer (not shown), the nozzle 3 is moved onto the stacking platform of the additive manufacturing apparatus (usually a flat surface), and the hydraulic composition is extruded (discharged) from the nozzle 3 to form a two-dimensional layered body. Subsequently, a second layered body is formed on top of this layered body, and the same operation is repeated thereafter to finally create a molded object consisting of a laminate with the desired shape.

[0033] The dimensions of the sculpture are, for example, 0.5 to 10 meters in length, 0.2 to 5 meters in width, and 0.2 to 5 meters in height. Examples of structures include pedestrian bridges, cylindrical columns, and two-seater benches. During the design phase, the target object may be designed by dividing it into two or more parts. When manufacturing the object, these two or more parts may be manufactured simultaneously, and then the manufactured parts may be combined to complete the target object. In this case, the time required to manufacture the object can be shortened. [Examples]

[0034] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. [Materials used] (1) Cement 1; manufactured by Taiheiyo Cement Corporation, ordinary Portland cement (2) Cement 2: High-early-strength Portland cement manufactured by Taiheiyo Cement Corporation (3) Cement 3: Manufactured by Taiheiyo Cement Corporation, moderate-heat Portland cement (4) Cement 4: Low-heat Portland cement manufactured by Taiheiyo Cement Corporation (5) Cement 5: Manufactured by Lafarge-Holcim, cement (6) Fine aggregate; No. 7 silica sand, maximum particle size: 0.3 mm or less (7) Rapid setting agent; Aluminum-based rapid setting agent, manufactured by Nippon Sika Co., Ltd., product name "Signit L53AF" (8) Thickening agent 1: Hydroxypropyl methylcellulose, viscosity: 15,000 mPa·s, manufactured by Sansho Co., Ltd., product name "NEOVISCO MC 150000" (9) Thickening agent 2: Hydroxypropyl methylcellulose, viscosity: 30,000 mPa·s, manufactured by Sansho Co., Ltd., product name "NEOVISCO MC 30000" (10) Thickening agent 3: Hydroxyethylcellulose, manufactured by Sansho Co., Ltd., product name "SANHEC-HHT" (11) Water; tap water (12) Inorganic powder 1; silica fume, BET specific surface area: 20 m² 2 / g, density: 2.33g / cm 3 (13) Inorganic powder 2; blast furnace slag fine powder, Blaine specific surface area: 3,200 cm² 2 / g, density: 3.01g / cm 3 This corresponds to blast furnace slag fine powder 4000 as specified in "JIS A 6206:2013 (Blast furnace slag fine powder for concrete)". (14) Inorganic powder 3; fly ash, blain. Specific surface area: 4,600 cm² 2 / g, density: 2.20g / cm 3 This corresponds to fly ash type II as specified in "JIS A 6201:2015 (Fly ash for concrete)". (15) Inorganic powder 4; limestone fine powder, Blaine specific surface area: 8,000 cm² 2 / g, density: 2.73g / cm 3 (16) Inorganic powder 5; Silica fine powder, BET specific surface area: 20m 2 / g, density: 2.71g / cm 3 (17) Fiber 1; Glass fiber, diameter: 0.2 mm, length: 10 mm, aspect ratio: 200 (18) Fiber 2; Synthetic fiber, vinylon fiber, diameter: 0.2 mm, length: 10 mm, aspect ratio: 200 Table 1 shows the proportions of alite, belite, aluminate phase, and ferrite phase in cements 1-5, calculated using Borg's formula.

[0035] [Table 1]

[0036] [Examples 1-6, Comparative Examples 1-3] Using a Hobart mixer, cement compositions were prepared by mixing the types of cement, water, and the amounts of fine aggregate shown in Table 2. The water-cement ratio was 40%. As an additive manufacturing apparatus, a gantry frame measuring 130 mm in height, 100 mm in width, and 1200 mm in depth, an extrusion nozzle with an inner diameter of 14 mm, a control computer, and a control panel were used. The prepared cement composition was placed in the cartridge of the additive manufacturing apparatus, and the hydraulic composition was extruded from the extrusion nozzle. Additive manufacturing was performed under conditions of an injection width of 16 mm, a layer thickness of 8 mm, and a layering speed of 30 mm / second to obtain a fabricated object. When extruding the hydraulic composition, the cement composition in the nozzle was mixed with the amount of quick-setting agent shown in Table 2 via a tube. The time from the supply of the quick-setting agent until the hydraulic composition for additive manufacturing (a mixture of cement composition and quick-setting agent) was extruded from the nozzle was approximately 3 seconds.

[0037] The self-supporting ability of the above-mentioned molded object was evaluated. The evaluation was performed by creating a square molded object with dimensions of 10 cm wide x 40 cm long x 40 cm high. First, the first layer was created, then the second layer was formed on top of the first layer, and the same process was repeated until the layering height reached 40-38 cm while maintaining self-supporting ability. This was rated as "5", "4" if the layering height reached 35 cm or more but less than 38 cm, "3" if the layering height reached 30 cm or more but less than 35 cm, "2" if the layering height reached 20 cm or more but less than 30 cm, and "1" if the layering height reached 10 cm or more but less than 20 cm, or if the molded object collapsed when the layering height was less than 10 cm. Furthermore, the blockage within the additive manufacturing equipment was evaluated. The evaluation was as follows: a "5" indicates that the hydraulic composition is extruded from the nozzle and the layer width (width of the molded object made of the extruded hydraulic composition) meets the design value; a "4" indicates that the hydraulic composition is extruded from the nozzle, the layer width is shorter than the design value but the reduction rate is 5% or less, and the extrusion of the hydraulic composition can be continued without interruption; a "3" indicates that the hydraulic composition is extruded from the nozzle, the layer width is shorter than the design value but the reduction rate is greater than 5% and 10% or less, and the extrusion of the hydraulic composition can be continued without interruption; a "2" indicates that the hydraulic composition is extruded from the nozzle but the extrusion is interrupted and discontinuous; and a "1" indicates that the hydraulic composition is not extruded from the nozzle. The results are shown in Table 2.

[0038] [Table 2]

[0039] [Example 7] The molded object was created in the same manner as in Example 1, except that before supplying and mixing the rapid-setting agent to the cement composition in the nozzle using a tube, the thickening agent 1 was supplied and mixed to the cement composition in the nozzle using a tube (different from the one used to supply the rapid-setting agent). The amount of thickening agent was 0.6 parts by mass per 100 parts by mass of cement, and the thickening agent was added and mixed approximately 3 seconds before the rapid-setting agent was added and mixed. The surface appearance (presence or absence of voids) of the hardened molded object was visually evaluated. In the above evaluation, "◎" indicates that no voids due to entrained air were observed on the surface of the printed object; "〇" indicates that there were almost no voids due to entrained air on the surface of the printed object; "△" indicates that voids due to entrained air were observed on the surface of the printed object; and "×" indicates that many voids due to entrained air were observed on the surface of the printed object, resulting in a poor appearance.

[0040] [Example 8] A molded object was created in the same manner as in Example 1, except that a quick-setting agent was supplied to the cement composition in the nozzle using a tube and mixed, and at the same time, a thickening agent 1 was supplied to the cement composition in the nozzle using a tube (different from the one used to supply the quick-setting agent) and mixed. The amount of thickening agent was 0.6 parts by mass per 100 parts by mass of cement. The appearance of the surface of the molded object after hardening (presence or absence of voids) was visually evaluated in the same manner as in Example 7. [Example 9] A molded object was created in the same manner as in Example 1, except that a quick-setting agent was supplied to the cement composition in the nozzle using a tube and mixed, and then a thickening agent 1 was supplied to the cement composition in the nozzle using a different tube (different from the one used to supply the quick-setting agent) and mixed. The amount of thickening agent was 0.6 parts by mass per 100 parts by mass of cement. The time from supplying and mixing the thickening agent until the hydraulic composition (mixture of cement composition and quick-setting agent) was extruded from the nozzle was approximately 1 second. The surface appearance (presence or absence of voids) of the molded object after hardening was visually evaluated in the same manner as in Example 7.

[0041] [Example 10] A molded object was created in the same manner as in Example 7, except that thickener 2 was used instead of thickener 1. The surface appearance (presence or absence of voids) of the molded object after hardening was visually evaluated. The results are shown in Table 3.

[0042] [Table 3]

[0043] [Example 12] Eight different types of molded objects were created in the same manner as in Example 7, except that the amount of thickener supplied per 100 parts by mass of cement was changed to the amount shown in Table 4. The surface appearance (presence or absence of voids) of each molded object after hardening was visually evaluated. The results are shown in Table 4. Furthermore, for Examples 7 to 12, the self-supporting ability of the molded objects and the ability to block the additive manufacturing apparatus were evaluated in the same manner as in Examples 1 to 6, and all were scored as "4".

[0044] [Table 4]

[0045] Table 2 shows that while Comparative Examples 1-2 (where the proportion of ferrite phase in the cement is 3.0% by mass) and Comparative Example 3 (where no quick-setting agent is used) all received a rating of "1" for either self-supporting or occluding properties, none of Examples 1-6 received a rating of "1" for either self-supporting or occluding properties. This indicates that the molding method of the present invention can produce structures with excellent self-supporting and occluding properties. From Examples 7 to 9 in Table 3, the method of supplying and mixing the thickener before supplying and mixing the rapid setting agent (Example 7) can result in an excellent appearance of the molded object. Furthermore, from Examples 7, 10-11, it can be seen that the appearance of the molded object in Example 7, which uses hydroxypropyl methylcellulose with a viscosity of 15,000 mPa·s, is the best. Table 4 shows that the appearance of the molded object is best when the supply amount of thickener is 0.1 to 0.9 parts by mass.

[0046] [Examples 13-24] Using a Hobart mixer, cement 1, fine aggregate, silica fume, and water in the amounts shown in Table 5 were mixed to prepare a cement composition. A molded object was obtained in the same manner as in Example 1, except that the obtained cement composition was used. The self-supporting ability of the molded object and the blockage of the additive manufacturing apparatus were evaluated in the same manner as in Example 1. The results are shown in Table 5. Table 5 shows that in Examples 13-16 (where the amount of water was 40 parts by mass and the amount of quick-setting agent was 2.5 parts by mass), the self-supporting ability was rated as "4" and the occluding ability was rated as "5", while in Examples 17-23 (where the amount of water was 20-30 parts by mass and the amount of quick-setting agent was 1.5-2.0 parts by mass), the self-supporting ability was rated as "5" and the occluding ability was rated as "4". Furthermore, in Example 24 (where the amount of silica fume was 5 parts by mass, the amount of water was 20 parts by mass, and the amount of quick-setting agent was 1.5 parts by mass), the occluding ability was rated as "3".

[0047] [Table 5]

[0048] [Examples 25-36] Using a Hobart mixer, cement 1, fine aggregate, blast furnace slag powder (referred to as "blast furnace slag" in Table 6), and water in the amounts shown in Table 6 were mixed to prepare a cement composition. A molded object was obtained in the same manner as in Example 1, except that the obtained cement composition was used. The self-supporting ability of the molded object and the blockage of the additive manufacturing apparatus were evaluated in the same manner as in Example 1. The results are shown in Table 6. Table 6 shows that in Examples 25-28 (where the amount of water is 40 parts by mass and the amount of quick-setting agent is 2.8 parts by mass), the self-supporting ability was rated as "4" and the occluding ability was rated as "5", in Examples 29-32 (where the amount of water is 30 parts by mass and the amount of quick-setting agent is 2.2 parts by mass), the self-supporting ability was rated as "4" and the occluding ability was rated as "4", and in Examples 33-36 (where the amount of water is 20 parts by mass and the amount of quick-setting agent is 1.7 parts by mass), the self-supporting ability was rated as "5" and the occluding ability was rated as "4".

[0049] [Table 6]

[0050] [Examples 37-48] Using a Hobart mixer, cement 1, fine aggregate, fly ash, and water in the amounts shown in Table 7 were mixed to prepare a cement composition. A molded object was obtained in the same manner as in Example 1, except that the obtained cement composition was used. The self-supporting ability of the molded object and the blockage of the additive manufacturing apparatus were evaluated in the same manner as in Example 1. The results are shown in Table 7. Table 7 shows that in Examples 37-40 (where the amount of water is 40 parts by mass and the amount of quick-setting agent is 2.6 parts by mass), the self-supporting ability was rated as "4" and the occluding ability was rated as "5", in Examples 41-44 (where the amount of water is 30 parts by mass and the amount of quick-setting agent is 2.1 parts by mass), the self-supporting ability was rated as "4" and the occluding ability was rated as "4", and in Examples 45-48 (where the amount of water is 20 parts by mass and the amount of quick-setting agent is 1.6 parts by mass), the self-supporting ability was rated as "5" and the occluding ability was rated as "4".

[0051] [Table 7]

[0052] [Examples 49-60] Using a Hobart mixer, cement 1, fine aggregate, limestone powder, and water in the amounts shown in Table 8 were mixed to prepare a cement composition. A molded object was obtained in the same manner as in Example 1, except that the obtained cement composition was used. The self-supporting ability of the molded object and the blockage of the additive manufacturing apparatus were evaluated in the same manner as in Example 1. The results are shown in Table 8. From the comparison of Examples 49-52 and 53-56 in Table 8, it can be seen that when the amount of limestone powder is large, the self-supporting ability improves, and when the amount of limestone powder is small, the occluding ability tends to improve.

[0053] [Table 8]

[0054] [Examples 61-68] Using a Hobart mixer, cement 1, fine aggregate, the types of fibers shown in Table 9, and water were mixed to prepare a cement composition. A molded object was obtained in the same manner as in Example 1, except that the obtained cement composition was used. The self-supporting ability of the molded object and the blockage of the additive manufacturing apparatus were evaluated in the same manner as in Example 1. The results are shown in Table 9. From the comparison of Examples 61-64 and 65-68 in Table 9, it can be seen that when the amount of fiber is high, the self-supporting properties tend to improve, and when the amount of fiber is low, the occlusal properties tend to improve.

[0055] [Table 9]

[0056] [Examples 69-80] Using a Hobart mixer, cement 1, fine aggregate, silica powder, and water in the amounts shown in Table 10 were mixed to prepare a cement composition. A molded object was obtained in the same manner as in Example 1, except that the obtained cement composition was used. The self-supporting ability of the molded object and the blockage of the additive manufacturing apparatus were evaluated in the same manner as in Example 1. The results are shown in Table 10. A comparison of Examples 69-80 in Table 10 shows that when the amount of water is large, the occludability improves, and when the amount of water is small, the self-supporting ability tends to improve.

[0057] [Table 10]

[0058] [Examples 81-103] Using a Hobart mixer, the types and amounts of materials shown in Table 11 (excluding quick-setting agents and thickeners) were mixed to prepare a cement composition. A molded object was obtained in the same manner as in Example 7, except that the obtained cement composition was used. The self-supporting ability of the molded object and its ability to block the additive manufacturing apparatus were evaluated in the same manner as in Example 7. The results are shown in Table 11.

[0059] [Table 11]

[0060] Table 11 shows that in Examples 81, 82, 97, 98, 101, and 102 (containing limestone powder, silica fume, and fibers, with a silica fume content of 10 to 15 parts by mass), both the self-supporting and occluding properties were evaluated as "5". [Explanation of symbols]

[0061] 1. Additive manufacturing equipment 2 Supply pipe 3 nozzles 4. The first container 5. Second container 6. The first supply route 7. Second supply channel 8. Cement composition 9. Fastening agent 10. Thickening agents 11 Hydraulic composition for additive manufacturing equipment

Claims

1. A method for forming a molded object using a hydraulic composition for additive manufacturing equipment, A cement composition preparation step involves mixing cement in which the proportion of the ferrite phase is 4.0% by mass or more, as calculated by Borg's formula, with water to obtain a cement composition. A thickening agent supply step of supplying a thickening agent in an amount of 0.01 to 2.0 parts by mass per 100 parts by mass of cement to the cement composition in the nozzle of the additive manufacturing apparatus, A rapid-setting agent supply step is performed to obtain the hydraulic composition for additive manufacturing equipment by supplying a rapid-setting agent in an amount of 0.2 to 5.0 parts by mass per 100 parts by mass of cement to the cement composition supplied with the thickener in the nozzle immediately before extruding the cement composition supplied with the thickener in the nozzle, An extrusion step of extruding the hydraulic composition for additive manufacturing apparatus from the additive manufacturing apparatus, The process includes a molding step of forming the above-mentioned molded object using the extruded hydraulic composition for additive manufacturing apparatus, A method for forming a molded object, characterized in that the viscosity of the thickening agent is 12,000 to 20,000 Pa·s.

2. In the thickening agent supply step, the supply of the thickening agent is performed 1 to 10 seconds before the rapid setting agent is supplied to the cement composition to which the thickening agent has been supplied. The method for forming a molded object according to claim 1, wherein in the above-mentioned rapid-setting agent supply step, the supply of the rapid-setting agent is performed 1 to 10 seconds before the hydraulic composition for the additive manufacturing apparatus is extruded from the nozzle to the outside.

3. The method for forming a molded object according to claim 1 or 2, wherein in the cement composition preparation step described above, an amount of inorganic powder (excluding cement) in the form of 2 to 150 parts by mass is mixed with 100 parts by mass of cement.

4. The method for forming a molded object according to claim 3, wherein the inorganic powder is one or more selected from silica fume, blast furnace slag fine powder, fly ash, limestone fine powder, and silica stone fine powder.

5. The method for forming a molded object according to any one of claims 1 to 4, wherein in the cement composition preparation step described above, an amount of fiber equal to 0.1 to 4.0 parts by mass is further mixed with 100 parts by mass of cement.

6. The method for forming a molded object according to any one of claims 1 to 5, wherein the thickening agent is one or more thickening agents selected from cellulose-based, acrylic-based, and glycol-based.

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