JP7149687B2 - additive manufacturing method - Google Patents

Description

The present invention relates to an additive manufacturing method for modeling using a cementitious kneaded material and an additive manufacturing device (3D printer).

2. Description of the Related Art In recent years, additive manufacturing apparatuses capable of forming delicate shapes by successively solidifying and layering molding materials such as resin while continuously extruding them onto a loading table (pedestal) have become widespread.
In addition to resin, recently, a method of modeling using a hydraulic material such as cement or gypsum and an additive manufacturing apparatus has been proposed. For example, in the modeling method described in Patent Document 1, a granular modeling material (alkali metal silicate) containing cement as an auxiliary binder is spread in layers in a modeling region, and the step of hardening the layers is repeated. This is a method of additively manufacturing a model.

However, in these methods, since powder remains in areas other than the solidified range, it is necessary to remove the powder in the final stage of modeling, which is time-consuming. In addition, when a hydraulic kneaded material is used as a molding material, the additive manufacturing equipment of the material extrusion (ME) method has a limited usable life due to a decrease in fluidity due to the progress of hydration of the hydraulic kneaded material. If the fluidity declines quickly, the hydraulic kneaded material hardens and clogs the additional manufacturing equipment and supply pipes, which may make it impossible to continue the modeling work. In addition, gypsum generally has a lower strength than cement.

Japanese Patent Publication No. 2014-516845

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an additive manufacturing method capable of manufacturing shaped objects having delicate and diverse designs by using a cementitious kneaded material and an additive manufacturing apparatus.

As a result of intensive studies in order to solve the above-mentioned problems, the inventors of the present invention have found that an additive manufacturing method in which a cementitious kneaded material is extruded by a specific method (means) to produce a shaped article is one in which hydration of the cementitious kneaded material progresses. As a result, the inventors have found that even if the fluidity of the kneaded product is lowered, it is possible to stably produce shaped articles having delicate and diverse designs, and have completed the present invention.
That is, the present invention is an additive manufacturing method having the following configurations.

[1] (A) A kneading step of adding 15 to 35 parts by mass of water to 100 parts by mass of the cement composition for modeling and kneading to obtain a cementitious kneaded product;
(B) An additive manufacturing method comprising at least an extrusion step for extruding and hardening the cementitious kneaded material to obtain a shaped article. however,
(A-1) The cement composition for molding contains at least 25 to 70% by mass of a cement-containing binder, 0.1 to 5% by mass of an admixture, and 25 to 70% by mass of fine aggregate,
(A-2) The cement-containing binder comprises 50 to 90% by mass of cement, 7 to 30% by mass of amorphous aluminosilicate, and gypsum and/or alkali metal sulfate of the amorphous aluminosilicate. Contains 10 to 150 parts by mass per 100 parts by mass of salt. again,
(B-1) The extruding step is a step of pressurizing the cartridge filled with the cementitious kneaded material to 50 kPa or more to extrude the cementitious kneaded material,
(B-2) The cartridge has a piston and a nozzle, and the internal cross-sectional area of the outlet of the nozzle attached to the cartridge is 0.1 to 1 cm ² .
[2] The addition according to [1 ] above, wherein (A) the kneading step is a step of putting the cement composition for modeling and water into a bag and kneading the entire bag with a non-shear mixing type mixer. Production method.
[3] The above [ 2 ], wherein the non-shear mixing type mixer is an oscillating mixer, a tilting drum mixer, a drum mixer, a rice cake maker, a washing machine, a paddle type mixer, or a pan type granulator. The additive manufacturing method described in .

The additive manufacturing method of the present invention can supply a fresh cementitious kneaded material in a timely and rapid manner. Molded objects with various designs can be manufactured stably.

It is a figure which shows an example of the cartridge used by the extrusion process in the addition manufacturing method of this invention. It is a photograph which shows the whole additional manufacturing apparatus (an example) which mounted the cartridge. 4 is a photograph showing a rack and pinion mechanism (one example) installed in the additive manufacturing equipment for pressurizing the cartridge. 1 is a photograph showing a state in which a cylindrical cartridge used in Examples is filled with a cementitious kneaded material. 1 is a photograph showing an example of a model (modeled object) formed in an example.

As described above, the addition manufacturing method of the present invention includes (A) a kneading step of kneading the cement composition for modeling and water to obtain a cementitious kneaded product, and (B) extruding the cementitious kneaded product to harden it. The manufacturing method includes at least an extrusion step for obtaining a modeled article by extruding.
Hereinafter, the present invention will be described in detail by dividing into (A) the kneading step, (B) the extrusion step, (C) the cement composition for modeling, and (D) the cementitious mixture.

(A) Kneading step The kneading step is a step for kneading the cement composition for modeling and water to obtain a cementitious kneaded product. The kneading in the kneading step is not particularly limited, but it is preferable to put the cement composition for modeling and water in a bag and knead the entire bag with a non-shear mixing type mixer. By opening a hole in a part of the bag, the kneaded material in the bag can be easily poured into the cartridge used in the later-described extrusion process without getting the hands dirty. In kneading using a non-shear mixing type mixer, the cement composition for molding and water can be sufficiently kneaded in the bag without breaking the bag because there is no or very weak shear force. Further, since the kneaded material in the bag does not adhere to the inside of the mixer, it is not necessary to wash the mixer. Furthermore, in the kneading process using this bag, since a plurality of types (formulations) of cement composition for molding and water can be put into separate bags and kneaded, a kneaded product of a plurality of formulations can be kneaded in one operation. There is also the advantage that it can be obtained with
Here, examples of the bag include a plastic bag, a rubber bag, a piping bag, a triangular pack, a flexible container, a flexible container bag (flexible container bag), and the like. Methods for closing the opening of the bag include a method of binding the opening of the bag with a vinyl tape, zipper, zip lock, clip, rubber plug, screw plug, heat sealing, or the like.
In addition, the non-shear mixing type mixer includes an oscillating mixer, a tilting mixer, a drum type rotating machine (e.g., a dryer, a ball mill that does not use balls, etc.), a rice cake pounding machine, a washing machine, a paddle type mixer, Alternatively, a pan-type granulator and the like can be mentioned.

(B) Extrusion step The extrusion step is a step for extruding and hardening the cementitious kneaded material to obtain a shaped article. For example, pressurizing the cartridge filled with the cementitious kneaded material to A process (method) of extruding a cementitious kneaded material can be mentioned.
The cartridge is preferably a cartridge 2 having a piston 21 and a nozzle 23 from the viewpoint of efficiency of pressurization and extrusion, as shown in FIG. 1 which will be described later. The cross-sectional area of the inner side of the discharge port of the nozzle 23 attached to the cartridge 2 is not particularly limited, but is preferably 0.1 to 1 cm ² , more preferably 0.2 to 0.8 cm ² . If the outlet of the nozzle 23 is 1 cm ² or less, it is possible to obtain a molded object having delicate and various designs, but if it is less than 0.1 cm ² , extrusion may become difficult.
The extrusion pressure is preferably 50 kPa or higher, more preferably 100 kPa or higher. In this way, the cartridge-type piston can be extruded at a high pressure of 50 kPa or more, so the nozzle outlet can be narrowed, and the cementitious kneaded material can be extruded without separating or deforming after lamination. In addition, it is possible to stably manufacture molded objects having various designs. The upper limit of the extrusion pressure is preferably 500 kPa, although it depends on the pressure resistance of the cartridge and nozzle.
Moreover, the system using the cartridge 2 filled with the cementitious kneaded material has the following advantages (i) to (iv). i.e.
(i) By filling the cartridge 2 with the cementitious kneaded material while vibrating the cartridge 2, air bubbles in the cementitious kneaded material can be easily removed, and a molded object with no (few) air bubbles can be produced.
(ii) By preparing a plurality of cartridges 2 filled with cementitious kneaded material, a cementitious kneaded material of stable quality can be prepared in a timely and rapid manner by a simple operation of exchanging the cartridges 2. Since the additional manufacturing apparatus can be replenished without contamination, molding can be continuously and stably performed, and even if the nozzle 23 is clogged, it can be dealt with easily and quickly by exchanging the cartridge 2.例文帳に追加
(iii) Use of the cartridge 2 eliminates the need for a cementitious kneaded product storage tank, supply pump, and supply piping, thereby simplifying the additional manufacturing equipment.
(iv) Since the piston 21 attached to the cartridge 2 is simply pressurized to push out the cementitious kneaded material, the extrusion speed can be easily adjusted (controlled). No sagging occurs from the discharge port of the nozzle 23 even when stopped.
The method of pressurizing the cartridge 2 is not particularly limited, but as shown in FIG. 3 described later, the pressure is directly transmitted to the piston 21 using a rack and pinion mechanism driven by an electric motor installed in the additional manufacturing equipment. This method is preferred because it can be extruded under high pressure. Moreover, as the cartridge 2, for example, a cylindrical container used in a commercially available caulking gun can be used.
The positioning mechanism of the nozzle 23 when extruding the cementitious kneaded material adopts a mechanism of orthogonal axes, which is a mechanism adopted in general additive manufacturing equipment. , the Y-axis and the Z-axis, a parallel link mechanism can be used. Here, the parallel link mechanism is a mechanism that always moves three motors simultaneously while being linked in parallel to determine the positions of the X-, Y-, and Z-axes. Additive manufacturing equipment that employs a parallel link mechanism enables faster positioning of the nozzle (injection head) and reduces the load on the motor and vibration caused by inertia during positioning, enabling higher-precision molding. This is preferable as the nozzle positioning mechanism of the present invention.

(C) Cement composition for modeling Next, the cement composition for modeling will be described.
A cement composition for shaping is a composition containing at least 25 to 70% by mass of a cement-containing binder, 0.1 to 5% by mass of an admixture, and 25 to 70% by mass of fine aggregate. However, the total amount of the cement-containing binder, admixture and fine aggregate is 100% by mass. When each component is within the above range, the cementitious kneaded product has high thixotropy and excellent moldability.
The content of the cement-containing binder is preferably 35-65% by mass, more preferably 40-60% by mass, and the content of the admixture is preferably 0.3-4.0% by mass, more preferably 0.3-4.0% by mass. It is preferably 0.5 to 3.5% by mass, and the fine aggregate content is preferably 35 to 65% by mass, more preferably 40 to 60% by mass.
Hereinafter, further description will be given separately for (i) cement-containing binders, (ii) admixtures, and (iii) fine aggregates.

(i) Cement-Containing Binder The cement-containing binder is a mixture containing cement, amorphous aluminosilicate, and gypsum and/or alkali metal sulfate as essential components.
The cements include white Portland cement, ordinary Portland cement, high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, silica-fume-containing cement, blast-furnace cement, fly-ash cement, alumina cement, ultra-rapid-hardening cement, colloidal cement, and ecocement. and the like.
The content of cement in the cement-containing binder is preferably 50-90% by mass. If the value is less than 50% by mass, the short-term strength of the shaped product may not be sufficiently expressed, and if it exceeds 90% by mass, the content of essential components other than cement in the cement-containing binder will be correspondingly low. As a result, the thixotropic property may be lowered, and the shape retention may be lowered. The cement content is more preferably 60 to 85% by mass, still more preferably 65 to 80% by mass.

The amorphous aluminosilicates include A-type, X-type, Y-type, Pc-type, and T-type zeolites, kaolin, analcyme, chabasite, mordenite, erionite, faujasite, and clinopatirolite. Amorphized aluminosilicate obtained by subjecting one or more selected materials to one or more treatments selected from acid treatment, ion exchange treatment, and calcination treatment. In addition, fly ash or the like, which is partly amorphous, can also be used.
The content of amorphous aluminosilicate in the cement-containing binder is preferably 7-30% by mass. If the value is less than 7% by mass, the thixotropic property is lowered and the shape retention is not sufficient. There is The content of amorphous aluminosilicate is more preferably 7 to 25% by mass, still more preferably 10 to 20% by mass.

The gypsum includes one or more selected from anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. In addition to natural gypsum, the gypsum may be by-product gypsum such as hydrofluoric gypsum, phosphate gypsum, mirabilite gypsum, excreted gypsum, or recycled gypsum obtained by heat-treating waste materials such as waste gypsum boards.
The alkali metal sulfate includes one or more selected from sodium sulfate, potassium sulfate, lithium sulfate, sodium hydrogensulfate, and potassium hydrogensulfate.
The amount of gypsum and/or alkali metal sulfate compounded in the cement-containing binder is preferably 10 to 150 parts by mass, more preferably 20 to 120 parts by mass, and still more preferably 100 parts by mass of the amorphous aluminosilicate. is 30 to 100 parts by mass.
When gypsum and alkali metal sulfate are used together, the ratio of gypsum and alkali metal sulfate is not particularly limited, but the mass ratio of gypsum:alkali metal sulfate is preferably 99.99:0.01 to 70: 30, more preferably 99.95:0.05 to 80:20.

The cement-containing binder preferably further contains calcium hydroxide. The content of calcium hydroxide in the cement-containing binder is preferably 5 mass % or less, more preferably 0.5 to 4.5 mass %, still more preferably 1 to 3 mass %. When the content of calcium hydroxide is within the above range, the cement kneaded product has improved rapid hardening property and shape retention due to thixotropy.

(ii) Admixture The admixture is a mixture containing, as essential ingredients, a water reducing agent, an antifoaming agent, and a thickening agent and/or powdered cellulose.
The water reducing agent has a main chain of a salt of melamine sulfonic acid formaldehyde condensate (melamine type), a salt of naphthalene sulfonic acid formaldehyde condensate (naphthalene type), a copolymer of acrylate-acrylic acid ester, etc., and polyethylene oxide or the like. As a graft chain, a polycarboxylic acid-based water reducing agent generally used for concrete can be used, but in the present invention, a melamine-based water reducing agent is particularly preferred.
The water-reducing agent may be liquid or powdery, but the powdery one is preferred for convenience of handling.
The ratio of the water reducing agent in the admixture is preferably 5 to 60% by mass, more preferably 10 to 40% by mass, based on 100% by mass of the admixture, from the viewpoint of improving fluidity.

Examples of the antifoaming agent include one or more selected from silicone, ether, mineral oil, ester, emulsion, nonionic, and the like.
The antifoaming agent may be in the form of an emulsion or a powder, but the powder form is preferred from the standpoint of convenience in handling.
The proportion of the antifoaming agent in the admixture is preferably 1 to 300 parts by mass, more preferably 3 to 200 parts by mass, and still more preferably 5 to 150 parts by mass with respect to 100 parts by mass of the water reducing agent. When a melamine powder water reducing agent is used as the water reducing agent, the proportion of the defoaming agent is preferably 2 to 200 parts by mass, more preferably 2.5 to 200 parts by mass, per 100 parts by mass of the melamine powder water reducing agent. 150 parts by mass, more preferably 5 to 100 parts by mass. If the ratio of the antifoaming agent is within this range, entrainment of air can be suppressed.

The thickening agent is not particularly limited as long as it has a thickening effect. Ethyl ethyl cellulose (HEEC), alginic acid, β-1,3 glucan, pullulan, welan gum, xanthan gum, guar gum, carrageenan, galactomannan, pectin, methyl starch, ethyl starch, propyl starch, methyl propyl starch, hydroxyethyl starch, hydroxypropyl starch , thickening polysaccharides such as hydroxypropylmethyl starch; polyacrylic acid; polyvinyl alcohol; polyethylene glycol;
The powdered cellulose is cellulose fibers having a fiber length of 18 to 1000 μm and a fiber diameter of 15 to 50 μm.

The ratio of the thickening agent and/or powdered cellulose in the admixture is preferably 5 to 900 parts by mass, more preferably 10 to 800 parts by mass, and still more preferably 15 to 700 parts by mass with respect to 100 parts by mass of the water reducing agent. part by mass. When a melamine powder water reducing agent is used as the water reducing agent, the proportion of the thickener and/or powdered cellulose is preferably 10 to 600 parts by mass, more preferably 100 parts by mass, per 100 parts by mass of the melamine powder water reducing agent. is 20 to 550 parts by mass, more preferably 30 to 500 parts by mass. If the ratio of the thickener and/or the powdered cellulose is within this range, the viscosity is appropriate, so that the shapeability is high, and the shape retention is also excellent.
When a thickener and powdered cellulose are used in combination, the ratio of the thickener to the powdered cellulose is not particularly limited, but the mass ratio of the thickener to the powdered cellulose is preferably 99:1 to 1:99, or more. It is preferably 98:2 to 2:98.

(iii) Fine aggregate The fine aggregate is one or more selected from river sand, land sand, sea sand, crushed sand, lightweight aggregate, heavy aggregate, slag aggregate, limestone sand, silica sand, and artificial sand. . And the maximum particle size of the fine aggregate is preferably 2.5 mm or less. If the maximum particle diameter of the fine aggregate exceeds 2.5 mm, it becomes difficult to form a delicate design. From the viewpoint of the delicacy of the design, the maximum particle size of the fine aggregate is more preferably 1.8 mm or less, more preferably 0.6 mm or less, and may be in the form of powder.

(iv) Other optional components of the cement composition for modeling can contain ingredients. For example, the optional components include various slags (blast furnace slag, slow-cooled slag, steel slag, etc.), pozzolanic substances, expansive agents, shrinkage reducing agents, polymer dispersions (liquid emulsions, re-emulsified powders, etc.) It does not matter.), hollow fine particles, resin powders, curing retardants, fibers, foaming agents, foaming agents, air entraining agents, and the like.

(D) Cementitious kneaded product The kneaded product is obtained by kneading the cement composition for modeling with water, and the fluidity of the cementitious kneaded product preferably conforms to JIS R 5201 "Physical test methods for cement". After filling the specified flow cone with the kneaded material, remove the flow cone vertically, apply vibration of 50 Hz for 10 seconds, and when the flow stops, the flow value is 150 to 220 mm. If the cementitious kneaded material has this flow value, it is possible to easily control the start and stop of extrusion of the kneaded material from the nozzle 23 of the cartridge 2 used in the extrusion step of the additive manufacturing method of the present invention. In addition, the kneaded product after extrusion stands on its own and has high formability.
The cementitious kneaded product is prepared by adding preferably 15 to 35 parts by mass of water to 100 parts by mass of the cement composition for molding and kneading the mixture. If the amount of water is within this range, the flow value of the cementitious kneaded product will be within the range of 150 to 220 mm, and the viscosity will be appropriate and the formability will be high. In addition, the water to be used may be tap water.

The cementitious mixture used in the present invention may further contain a hardening accelerator as an optional component.
A cementitious mixture containing a hardening accelerator is a mixture obtained by contacting a cementitious mixture containing no hardening accelerator with a hardening accelerator. The use of a hardening accelerator accelerates the hardening of the cementitious kneaded material and improves the molding efficiency. Here, contacting the cementitious kneaded material with the hardening accelerator means an act such as dropping, coating, spraying, or spraying the hardening accelerator on the cementitious kneaded material layer, or including the hardening accelerator in the cementitious kneaded material. Say.
The hardening accelerator is one or more solids (powder) selected from aluminates, carbonates, silicates, calcium aluminates, calcium sulfoaluminates, aluminum sulfates, and alums, suspensions, Alternatively, an aqueous solution can be used, but an aqueous solution containing aluminum sulfate as a main component is particularly preferred from the viewpoint of curing acceleration, long-term strength development, and safety in work.
The concentration of aluminum sulfate in the aluminum sulfate aqueous solution is preferably 5% by mass or more. If the concentration is less than 5% by mass, the acceleration of curing is small. Note that the upper limit of the concentration is the saturated concentration. If the hardening of the cementitious kneaded material as the lower layer progresses and the surface is dry, it becomes difficult to integrate with the upper layer of the cementitious kneaded material. Forming the upper layer of cementitious mixture in a state of hardening before termination is preferable for ensuring integrity.

The method of curing the shaped object manufactured by the additive manufacturing method of the present invention is not particularly limited, and one or two or more curing methods may be used in combination. One or more selected from curing, steam curing, underwater curing, thermal curing, carbon dioxide curing, autoclave curing and the like can be used.

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.
1. Materials Used A molding cement composition containing the following cement-containing binder, admixture, and fine aggregate, and the following water were used.
(1) Cement composition for modeling (1-1) Cement-containing binding material (i) Cement: White Portland cement (manufactured by Sanyo White Cement Co., Ltd.)
(ii) Amorphous aluminosilicate: Metakaolin (trade name MetaMax HRM, manufactured by BASF Japan)
(iii) Gypsum: type II anhydrous gypsum (manufactured by Asahi Glass Co., Ltd.)
(iv) Calcium hydroxide (manufactured by Shigean Lime Co., Ltd.)
(v) Alkali metal sulfate: Glauber's salt (manufactured by Tosoh Corporation)
(1-2) Admixture (i) Melamine-based powder water reducing agent: water reducing agent containing salt of melamine sulfonic acid formaldehyde condensate as an active ingredient (Melment [registered trademark], manufactured by BASF Japan)
(ii) Thickener: Thickening polysaccharide (trade name Esacol210H [registered trademark], manufactured by BASF Japan Ltd.)
(iii) Powdered cellulose: cellulose fine powder (trade name: Arbocel PWC500, manufactured by Rettenmeier)
(iv) Antifoaming agent: polyether antifoaming agent (trade name: Adecanate B317F, manufactured by ADEKA)
(1-3) Fine aggregate Limestone sand (maximum particle size 0.6 mm)
(2) Water Tap water

2. Kneading using the additive manufacturing method of the present invention In a polyethylene bag (35 cm long, 45 cm wide, 0.1 mm thick), 100 parts by mass (1000 g) of the cement composition for modeling shown in Table 1 was put, and 32 parts of water was added. After adding .5 parts by mass (325 g), the opening is wrapped with vinyl tape to seal, and kneaded using a non-shear mixing type mixer (product name: Standard O-M Mixer OM-5, manufactured by Chiyoda Machinery Co., Ltd.). to prepare a cementitious kneaded product.
Next, after filling the cementitious kneaded material into the flow cone defined in JIS R 5201 "Physical test method for cement", remove the flow cone vertically and apply vibration of 50 Hz for 10 seconds to make it flow. When the was stopped, the flow value was 193 mm.

3. Modeling using the additive manufacturing method of the present invention After vertically installing a cylindrical cartridge with an inner diameter of 4.9 cm and a length of 21.5 cm, the cementitious kneaded product is placed in a hole at the tip of the bag as shown in FIG. was opened and filled into the cartridge from the top of the cartridge while being vibrated. After filling, the cartridge was also shaken to remove trapped air bubbles in the cementitious kneaded material.
A piston was immediately inserted into the cartridge filled with the cementitious kneaded material from above, and the cartridge and the kneaded material were brought into close contact with each other until there was no gap between them. Vaseline is applied to the side of the piston to keep the cartridge and piston in close contact. The shape of the piston used was a hollow cylinder with a diameter of 4.8 cm and a length of 2 cm.
Next, use a tool with a sharp tip to the bottom of the cartridge to punch a hole in the aluminum foil seal that is pre-pasted inside the cartridge. made it possible to eject. The shape of the attached plastic nozzle is a truncated cone with an inner diameter of 1.6 cm at the base, a cross-sectional area inside the outlet of 0.28 cm ² , and a length of 5.7 cm. The cartridge to which the nozzle was attached was set at the position shown in FIG. 2 for stocking the cartridge of the additional manufacturing apparatus.
After the additional manufacturing apparatus was activated, the shape data of the molded object to be manufactured in advance was taken in, and the cartridge was completely set, the molding work was started. In the molding operation, the cartridge was first taken into the positioning mechanism, and the kneaded material was extruded from the cartridge by gripping the protrusion of the piston with a chuck. As shown in FIG. 3, by driving the electric motor installed in the additional manufacturing equipment, the piston was operated using the rack and pinion mechanism to control the start and stop of extrusion of the kneaded material. The load at the start of extrusion was 20 kg.
In addition, the positioning of the nozzle when extruding the kneaded material is performed by simultaneously and in parallel with three motors that determine the positions of the X-axis, Y-axis, and Z-axis using a parallel link mechanism that is used in general additive manufacturing equipment. The X-, Y-, and Z-axis positions were determined by moving while linking.
When the extrusion amount of the kneaded material from the cartridge (push amount of the piston) reached a predetermined value, the additional manufacturing apparatus automatically performed the cartridge exchange operation, and continued the molding operation. As a result of continuously performing the above operations, we were able to stably manufacture objects with delicate and diverse designs. FIG. 6 shows an example of the modeled object obtained.

2 cartridge 21 piston 22 cementitious mixture 23 nozzle

Claims (3)

(A) a kneading step of adding 15 to 35 parts by mass of water to 100 parts by mass of the cement composition for modeling and kneading to obtain a cementitious kneaded product;
(B) An additive manufacturing method comprising at least an extrusion step for extruding and hardening the cementitious kneaded material to obtain a shaped article. however,
(A-1) The cement composition for molding contains at least 25 to 70% by mass of a cement-containing binder, 0.1 to 5% by mass of an admixture, and 25 to 70% by mass of fine aggregate,
(A-2) The cement-containing binder comprises 50 to 90% by mass of cement, 7 to 30% by mass of amorphous aluminosilicate, and gypsum and/or alkali metal sulfate of the amorphous aluminosilicate. Contains 10 to 150 parts by mass per 100 parts by mass of salt. again,
(B-1) The extruding step is a step of pressurizing the cartridge filled with the cementitious kneaded material to 50 kPa or more to extrude the cementitious kneaded material,
(B-2) The cartridge has a piston and a nozzle, and the internal cross-sectional area of the discharge port of the nozzle attached to the cartridge is 0.1 to 1 cm ² . 2. The additive manufacturing method according to claim 1, wherein the kneading step (A) is a step of putting the cement composition for modeling and water into a bag and kneading the entire bag with a non-shear mixing type mixer. 3. The addition according to claim 2 , wherein the non-shear mixing type mixer is an oscillating mixer, a tilting drum mixer, a drum mixer, a rice cake maker, a washing machine, a paddle type mixer, or a pan type granulator. Production method.

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