JP7833804B2 - Method for manufacturing a hydraulic molded body - Google Patents

Description

Applicable to Article 30, Paragraph 2 of the Patent Law. Published on November 23, 2023 on the website of the religious corporation Komyoin (https://koumyouin.net/), published on November 23, 2023 on a video sharing site (https://www.youtube.com/watch?v=fy7D-OZmY-E&t=4940s), published within the religious corporation Komyoin on November 23, 2023, and published on November 23, 2023 in "Komyoin Gokotsubutsu Kanshabutsu" published by the religious corporation Komyoin.

This invention relates to a method for manufacturing a hydraulic molded article using cement.

Traditionally, it has been practiced to create objects such as Buddhist statues, tombstones, memorial tablets, lanterns, and animal figures from the bone powder remaining after cremation, and to enshrine these objects (see, for example, Patent Document 1). For instance, a bone Buddha statue, created from cremated remains, combines the worship of Buddha with the idea of ancestor veneration, thus attracting the faith of many people. Furthermore, because it contains cremated remains, a bone Buddha statue can also provide comfort to bereaved family members and those connected to the deceased.

However, conventional sculptures containing bone powder tend to have a low bone powder content in order to maintain strength, and it is desirable to include as much bone powder as possible. Furthermore, given social factors such as a declining birthrate, an aging population, a high death rate, and an increase in unclaimed graves, there is a growing consideration to collect bones that have been deceased for a certain period of time or bones of unclaimed individuals to create bone Buddhas, which will serve as objects of worship for many people. On the other hand, since bone Buddhas are often installed inside temples and shrines, it is desirable to include as much bone powder as possible in a bone Buddha of a limited size while maintaining strength.

Japanese Patent Application Publication No. 9-300896

This technology was proposed in light of the conventional situation described above, and provides a method for manufacturing hydraulic molded articles that can achieve excellent strength even with a high bone meal content.

As a result of diligent research, the inventors of this invention discovered that the above objective can be achieved by the following method for manufacturing hydraulic molded articles, and thus completed this technology.

[1]
A method for producing a hydraulic molded body, comprising casting a hydraulic composition containing Portland cement and bone meal, wherein the bone meal content excluding water is 30 to 60 wt%, into a mold, allowing it to harden, demolding, and removing the hydraulic molded body.
[2]
The method for producing a hydraulic molded article according to [1], wherein the bone meal content is 40 to 150 parts by mass per 100 parts by mass of the Portland cement.
[3]
The method for producing a hydraulic molded article according to [2], wherein the water-cement mass ratio of the hydraulic composition is 0.30 to 0.50.
[4]
A method for producing a hydraulic molded article according to any one of [1] to [3], wherein the Portland cement is white Portland cement.
[5]
A method for producing a hydraulic molded article according to any one of [1] to [3], wherein the hydraulic composition is a mortar composition.
[6]
A method for producing a hydraulic molded article according to any one of [1] to [3], wherein the size of the bone powder is 2 mm or less.
[7]
A method for manufacturing a hydraulic molded article according to any one of [1] to [3], wherein the mold is composed of multiple parts arranged in stages in the vertical direction from the bottom to the top, and the multiple parts are detachable.
[8]
A method for manufacturing a hydraulic molded body according to [7], wherein parts are removed in stages from the bottom to the top of the mold to take out the hydraulic molded body.
[9]
A method for manufacturing a hydraulic molded body according to any one of [1] to [3], wherein the hydraulic molded body is part of or all of a Buddhist statue.
[10]
A hydraulic molded article manufactured by the manufacturing method described in any of [1] to [9] above.

According to this technology, excellent strength can be obtained by using a hydraulic composition containing Portland cement and a predetermined amount of bone meal.

Figure 1 is a flowchart showing a method for manufacturing a hydraulic molded article using this technology. Figure 2 is a schematic front view of a bone Buddha statue. Figure 3 is a schematic front view showing the main image of the Buddha in a bone Buddha. Figure 4 is a schematic front view showing the upper lotus section of a bone Buddha statue. Figure 5 is a schematic front view showing the lower lotus section of a bone Buddha statue. Figure 6 is a schematic front view showing the halo portion of a bone Buddha statue. Figure 7 is a photograph showing a Buddhist statue made from bones using this technology.

Hereinafter, embodiments of the present invention will be described in detail in the following order with reference to the drawings.
1. Method for manufacturing hydraulic molded articles 2. Examples

<1. Method for manufacturing a hydraulic molded article>
Figure 1 is a flowchart showing a method for manufacturing a hydraulic molded body using this technology. As shown in Figure 1, the method for manufacturing a hydraulic molded body includes a preparation step (A) for preparing a hydraulic composition, a casting step (B) for casting the hydraulic composition into a mold, a curing step (C) for hardening the hydraulic composition, a demolding step (D) for demolding the hydraulic molded body from the mold, and a finishing step (E) for assembling and coloring the hydraulic molded body.

The hydraulic molded body may be all or part of a sculptural object such as a Buddhist statue, tombstone, memorial tablet, lantern, or animal. The bone powder is preferably made from crushed cremated bone, and preferably has been treated with sterilization, drying, and heating.

Below, as a specific example of a method for manufacturing a hydraulically hardened molded body, we will describe in detail the manufacturing process of a Buddhist statue made of bone, specifically the preparation process (A), casting process (B), hardening process (C), demolding process (D), and finishing process (E).

Figure 2 is a schematic front view of a bone Buddha, and Figures 3 to 6 are schematic front views of the main image section, upper lotus section, lower lotus section, and halo section of the bone Buddha, respectively. As shown in Figures 2 to 6, the manufacturing method of the bone Buddha, as a specific example, involves shaping the bone Buddha into four parts: the main image section 11, the upper lotus section 12, the lower lotus section 13, and the halo section 14, and then assembling these parts to create the bone Buddha.

[Preparation step (A)]
In preparation step (A), a hydraulic composition containing Portland cement and bone meal is prepared. The hydraulic composition may be a mortar composition containing fine aggregate or a concrete composition containing coarse aggregate. Here, fine aggregate refers to aggregate that passes through a 10 mm sieve and whose mass accounts for 85% or more of the total is less than 5 mm in size. Coarse aggregate refers to aggregate that accumulates on a 5 mm sieve and whose mass accounts for 85% or more of the total is 5 mm or larger. From the viewpoint of manufacturing a bone Buddha, it is preferable that the hydraulic composition is a mortar composition containing bone meal as fine aggregate. This makes it possible to make the surface smoother compared to a concrete composition containing coarse aggregate.

As for the Portland cement, Portland cement specified in JIS R 5210 (ordinary, rapid-hardening, extra-rapid-hardening, moderate-heat, low-heat, sulfate-resistant), or white Portland cement with reduced ferric oxide content can be used. From the viewpoint of manufacturing bone Buddha statues, white Portland cement is preferable. This allows the color of the bone powder to be visible and facilitates coloring.

Bone powder can be made from crushed human or animal bones. Furthermore, bone powder used in Buddhist altars can be made from crushed cremated bones. The main component of cremated bone is calcium phosphate, and a mortar composition containing cremated bone powder as fine aggregate can achieve strength equal to or greater than that of cement paste.

The bone powder particles are preferably 2 mm or smaller. Here, 2 mm or smaller means particles that pass through a 5 mm sieve and where at least 85% of the total mass is 2 mm or smaller. The small size of the bone powder improves the strength of the hydraulic molded body and allows for a smoother surface.

The bone meal content is preferably 30 wt% or more, more preferably 35 wt% or more, and even more preferably 40 wt% or more, in the hydraulic composition excluding water. Alternatively, the bone meal content is preferably 60 wt% or less, more preferably 55 wt% or less, and even more preferably 50 wt% or less, in the hydraulic composition excluding water. This allows for excellent strength of the hydraulic molded article even with a high bone meal content.

Furthermore, the bone meal content is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and even more preferably 60 parts by mass or more, per 100 parts by mass of Portland cement. Also, the bone meal content is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, even more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less, per 100 parts by mass of Portland cement.

The water-cement mass ratio of the hydraulic composition is preferably 0.30 or higher, more preferably 0.32 or higher, and even more preferably 0.35 or higher. Furthermore, the water-cement mass ratio of the hydraulic composition is preferably 0.60 or lower, more preferably 0.50 or lower, and even more preferably 0.45 or lower. This allows for excellent strength of the hydraulic molded article even with a high bone meal content.

[Concrete pouring process (B)]
In the casting process (B), the hydraulic composition is cast into the mold of the prototype of the object to be molded. The mold of the prototype is not particularly limited, but it is preferable to create it by scanning the prototype using a 3D printer. This makes it possible to create molds of complex shapes without considering adhesion between the prototype and the mold, compared to creating a mold by applying FRP (Fiber Reinforced Plastics) or the like to the prototype.

The mold for the prototype preferably contains a water-containing hydraulic composition with a casting amount in the range of 50 kg to 200 kg. For example, in the case of manufacturing a bone Buddha, as shown in Figures 2 to 6, it is preferable to divide the prototype bone Buddha model into four parts—the main image section 11, the upper lotus section 12, the lower lotus section 13, and the halo section 14—and create the molds within the above casting amount range.

Furthermore, it is preferable that the prototype formwork is composed of multiple parts arranged in stages vertically from the bottom to the top, with the multiple parts being detachable. For example, it is preferable that the prototype formwork has parts that can be attached and detached at intervals of 50 mm to 200 mm vertically. This allows the pouring process (B), reaction process (C), and demolding process (D) to be repeatedly performed in stages vertically from the bottom to the top of the formwork.

Furthermore, it is preferable to apply a release agent to the inside of the parts into which the hydraulic composition is poured and allow it to dry beforehand. This allows the hydraulic composition to be poured and solidified in stages from the bottom to the top of the formwork, and also allows the formwork parts to be removed in stages from the bottom to the top, preventing cracks caused by insufficient water drainage, as will be described later.

[Curing step (C)]
In the hardening process (C), the hydraulic composition poured into the formwork is hardened to form a hydraulic molded body. The Portland cement in the hydraulic composition reacts with water (hydration reaction) to produce hard hydrates. These hydrates continue to be produced one after another until the hydration reaction is complete, binding the bone meal together and increasing the strength.

[Demolding process (D)]
In the demolding process (D), the hydraulic molded body is demolded from the mold. Demolding is preferably performed 1 to 3 days after casting. Furthermore, if the original mold is composed of multiple parts arranged in stages vertically from the bottom to the top, and the multiple parts are detachable, it is preferable to remove the parts in stages from the bottom to the top of the hardened area 1 to 3 days after casting, and then remove the hydraulic molded body. This prevents the occurrence of cracks due to insufficient water drainage.

The hydraulically hardened molded body, after being demolded from the mold, is preferably allowed to air dry for at least three months, more preferably four months, and even more preferably five months. Here, air drying refers to drying in air at room temperature (5°C to 35°C). Alternatively, the hydraulically hardened molded body may be dried at room temperature (15°C to 25°C) or in a constant temperature chamber. When drying the hydraulically hardened molded body in a constant temperature chamber, the temperature is preferably 10°C to 45°C, more preferably 20°C to 45°C, even more preferably 30°C to 45°C, and even more preferably 35°C to 45°C.

[Finishing Process (E)]
In the finishing process (E), the hydraulic molded body is assembled and colored. In the finishing process (E), for example, the four parts shown in Figures 3 to 6—the main image part 11, the upper lotus part 12, the lower lotus part 13, and the halo part 14—are assembled and colored to create the bone Buddha shown in Figure 2.

<2. Examples>
The following describes in detail some examples of this technology. In these examples, a hydraulic composition was prepared, and test specimens were made using it. The compressive strength of the test specimens was then evaluated. Furthermore, a Buddhist statue made from bone was made using the hydraulic composition. However, this technology is not limited to these examples.

[Test 1 - Test 11]
A hydraulic composition was prepared by mixing a hydraulic component, bone meal, and water in the proportions (parts by mass) shown in Table 1.
White cement: Taiheiyo Cement Co., Ltd., White Cement Resin gypsum: Yoshino Gypsum Sales Co., Ltd., Resin-filled hard gypsum Highstone HLP White Gypsum: Katei Kagaku Kogyo Co., Ltd., High-grade craft gypsum Bone meal: Crushed cremated bones with a maximum size of 2 mm or less

The water-soluble composition was cast into a mold for the test specimen, air-dried for 7 days, and demolded to obtain a cylindrical test specimen with a diameter of 66 mm and a height of 47 mm (cross-sectional area: 3420 ^mm² ). Then, in accordance with JIS A 1108, a compressive load was applied to the donor specimen at a speed of 1 mm/min using a universal material testing machine (Shimadzu Corporation, AG20kND), the maximum test force was measured, and the compressive strength was calculated (Saitama Prefectural Industrial Technology Center: No. I22-1613).

Table 1 shows the measurement results of the maximum test force and the calculation results of the compressive strength in Tests 1-11.

In Test 2-4, because white cement and bone meal were mixed, compressive strength equal to or greater than that of Test 1, which used only white cement paste, was achieved. In particular, Test 3-4 achieved superior compressive strength compared to Test 1.

In tests 5-7, resin gypsum was incorporated, and in tests 6-7, bone meal was incorporated. Compared to test 5 (residual resin gypsum paste only), the compressive strength was lower. In tests 8-11, gypsum was incorporated, and in tests 10-11, bone meal was incorporated. Compared to test 8 (residual gypsum paste only), the compressive strength was lower.

From Test 1-11, it was found that by using white cement as a hydraulic binder, excellent strength can be obtained even with a high bone meal content. In particular, it was found that excellent strength, equivalent to or better than that of white cement paste, can be obtained when the bone meal content (excluding water) is 30-60 wt%.

[Creation of a Bone Buddha]
As shown in Test 3, a hydraulic composition was prepared by mixing 120 parts by mass of white cement, 80 parts by mass of bone powder, and 45 parts by mass of water. The bone powder used was from the remains of 729 people interred in the "Tower of Gratitude," a perpetual memorial grave, over a ten-year period from April 2013 to March 2023.

The mold was created using a Dainichi Nyorai stone Buddha as the model prototype, and was divided into four parts: the main image section, the upper lotus section, the lower lotus section, and the halo section. Furthermore, the mold was constructed using a 3D printer, consisting of over 100 parts arranged in a vertical, stepped manner from the base to the top, with each part being detachable. The amount of hydraulic composition (including water) poured into the molds for the main image section, upper lotus section, lower lotus section, and halo section was 96.5 kg, 183.7 kg, 172.8 kg, and 62.4 kg, respectively.

The casting process involved gradually pouring the hydraulic composition from the bottom to the top of the mold. Demolding involved sequentially removing parts as they hardened, 1 to 3 days after casting. The removed hydraulic molded parts were then allowed to air dry for approximately 5 months. After air drying, the main image, upper lotus section, lower lotus section, and halo were assembled, painted, and the bone Buddha was constructed.

Figure 7 is a photograph showing a bone Buddha statue created using this technology. As shown in Figure 7, it was possible to create a bone Buddha statue with excellent strength without any cracks.

11 Gohonzon part, 12 Upper lotus part, 13 Lower lotus part, 14 Halo part

Claims (7)

A method for producing a hydraulic molded body, comprising: casting a hydraulic composition containing Portland cement and bone meal, wherein the bone meal content excluding water is 30 to 60 wt%, into a mold, allowing it to harden, demolding, and removing the hydraulic molded body;
The aforementioned formwork is composed of multiple parts arranged in stages vertically from the bottom to the top, and the multiple parts are detachable.
The parts are removed in stages from the bottom to the top of the mold, and the hydraulic molded body is taken out.
A method for manufacturing a hydraulically hardened molded article. The method for producing a hydraulic molded article according to claim 1, wherein the bone meal content is 40 to 150 parts by mass per 100 parts by mass of the Portland cement. The method for producing a hydraulic molded article according to claim 2, wherein the water-cement mass ratio of the hydraulic composition is 0.30 to 0.60. The method for producing a hydraulic molded article according to any one of claims 1 to 3, wherein the Portland cement is white Portland cement. A method for producing a hydraulic molded article according to any one of claims 1 to 3, wherein the hydraulic composition is a mortar composition. A method for producing a hydraulic molded article according to any one of claims 1 to 3, wherein the size of the bone powder is 2 mm or less. The method for manufacturing a hydraulic molded body according to any one of claims 1 to 3, wherein the hydraulic molded body is part of or all of a Buddhist statue.