Method for manufacturing structures for installation in water areas, spraying device, and structures for installation in water areas

Abstract

To provide a method for manufacturing a water body structure that promotes the formation of seaweed beds in water, which has a high effect in promoting seaweed bed formation and in which the sprayed layer is less likely to peel off from the substrate. [Solution] The method comprises a base layer formation step in which a base layer is formed by spraying a base layer spray material, which is a mixture of magnesium oxide, cotton-like bamboo fibers obtained by crushing and pulverizing raw bamboo rods so that the cell walls of the fiber cells are split, and granular anhydrous magnesium chloride with water or seawater, onto the surface of a substrate submerged in water; and a surface layer formation step in which, before the base layer formed in the base layer formation step solidifies, a surface layer spray material containing cotton-like bamboo fibers and granular sodium chloride is sprayed onto the surface of the base layer to form a surface layer in which the surface layer spray material has penetrated into the base layer.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a structure for underwater installation, a spraying device, and a structure for underwater installation for promoting the growth of underwater algal beds.

Background Art

[0002] As technologies for promoting the growth of underwater algal beds, there are known technologies such as installing a substrate for algal reefs underwater (see Non-Patent Document 1, pages 154-164), artificially supplying nutrients underwater (see Non-Patent Document 1, pages 165-173), and promoting the flow of water in the water area (see Non-Patent Document 1, pages 174-179). As substrates for algal reefs, blocks, stones, steel members, ropes, etc. are used (see Non-Patent Document 1, pages 155-156, 161-164). The supply of nutrients is to supply nutrients such as nitrogen, phosphorus, and iron necessary for the growth and maturation of algae by fertilization (artificially supplying components that are likely to be lacking in the water area). For fertilization, chemical fertilizers, organic fertilizers, iron components (slag-based fertilization materials), etc. are used. Flow promotion is based on the fact that sea urchins and sea cucumbers that cause grazing damage cannot distribute when the flow by waves is intense. By imitating the water depth and flow of the algal bed formed in the vicinity, rock throwing and block installation are carried out, and the flow is strengthened by raising the height, etc., to reduce grazing damage by herbivorous animals.

[0003] As technologies related to the above-mentioned provision of substrates for algal reefs, for example, those in which a planting board is attached to the substrate (see Patent Documents 4-9) and those in which planting pebbles are attached to the substrate (see Patent Document 10) are known.

[0004] On the other hand, separate from the supply of nutrients (fertilization) as described above, the present inventors have proposed in Patent Document 1 a technology to use a substrate submerged in water as a source of nutrients by attaching an induction and propagation material (cotton-like bamboo fiber) to induce and propagate nitrogen-fixing bacteria floating in the water, and by inducing and propagating nitrogen-fixing bacteria inside this induction material to perform nitrogen fixation. Patent Document 1 describes using a spray material for underwater greening that comprises "a granular spray base material containing magnesium oxide and cotton-like raw bamboo fiber obtained by compressing and crushing raw bamboo culms so that the cell walls of the fiber cells rupture, and a spraying-time additive liquid containing magnesium chloride dissolved in fresh water or seawater" or "a granular spray base material containing magnesium oxide and cotton-like raw bamboo fiber obtained by compressing and crushing raw bamboo culms so that the cell walls of the fiber cells rupture, and granular anhydrous magnesium chloride, and a spraying-time additive liquid containing fresh water or seawater." This underwater greening spray material is sprayed onto the surface of a structure (substrate) to be installed on the seabed or water's edge and allowed to solidify to manufacture a structure for installation in aquatic areas (see Figure 7 in the same document, and sections

[0072] -

[0083] of the specification). Furthermore, by adding 90 wt% or more of sodium chloride granules (granular sodium chloride) with a particle size of 0.1 mm to 12 mm to this underwater greening spray material, the surface of the sprayed layer becomes a cement binder consisting of aggregate and MOC cement (phosphate may be added in some cases), with granular sodium chloride and cotton-like raw bamboo fibers scattered within, some of which are visible on the surface (see Figure 12 in the same document). When the structure (substrate) with this sprayed layer formed on its surface is sunk to the seabed, after a long period of time, the granular sodium chloride dissolves in water and disappears, leaving voids (small holes) where the granular sodium chloride disappeared. The entry of microorganisms, aquatic plant roots, or holdfasts into the voids of these voids greatly promotes the proliferation of aquatic microorganisms or aquatic plants in the sprayed layer. Furthermore, because these voids increase the surface area of ​​the sprayed layer, nitrogen-fixing bacteria can more easily enter the cotton-like raw bamboo fibers within the cement binder (see the same reference specification

[0088] ). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2003-031272 [Patent Document 2] Japanese Patent No. 3999582 (Japanese Unexamined Patent Publication No. 2003-009714) [Patent Document 3] Japanese Patent No. 4166407 (Japanese Unexamined Patent Publication No. 2001-258420) [Patent Document 4] Japanese Utility Model Publication No. 57-201163 [Patent Document 5] Japanese Patent Application Publication No. 57-054540 [Patent Document 6] Japanese Utility Model Publication No. 58-013069 [Patent Document 7] Utility Model Registration No. 3082849 Specification [Patent Document 8] Utility Model Registration No. 3077630 Specification [Patent Document 9] Utility Model Registration No. 3043999 Specification [Patent Document 10] Japanese Patent Application Publication No. 09-271288 [Non-patent literature]

[0006] [Non-Patent Document 1] Fisheries Agency, "Guidelines for Countermeasures against Coastal Barrenness (3rd Edition)", [online], March 2021, Fisheries Agency, [Accessed December 17, 2024], Internet<URL:https: / / www.jfa.maff.go.jp / j / gyoko_gyozyo / g_gideline / index.html> . [Non-Patent Document 2] Mark Shand, “Magnesia Cements: From Formulation to Application”, Elsevier, 2020.6.16, ISBN:9780123919250. [Non-Patent Document 3] Kei Watanuki et al., "Dissolved Iron Concentration in Seaweed Beds," Proceedings of the 2015 Annual Meeting of the Japanese Society of Fisheries Engineering, Japanese Society of Fisheries Engineering, May 2015. doi:10.18903 / pamjsfe.2015.0_91. [Non-Patent Document 4] Fisheries Agency, "Technical Data on Fertilization for Countermeasures against Coastal Barrenness," March 2015. <URL:https: / / www.jfa.maff.go.jp / j / gyoko_gyozyo / g_zyoho_bako / attach / pdf / mobahozen_sozo_isoyaketaisaku-1.pdf> [Overview of the project] [Problems that the invention aims to solve]

[0007] In actual field applications, when a spray material containing magnesium oxide (and magnesium chloride), cotton-like bamboo fibers, and granular sodium chloride is mixed with freshwater or seawater and sprayed onto the substrate of a seaweed reef to form a sprayed layer, most of the cotton-like bamboo fibers and granular sodium chloride become encapsulated within the magnesia cement (cement formed when magnesium oxide (and magnesium chloride) reacts with water and hardens), and only a small portion of the total amount of cotton-like bamboo fibers and granular sodium chloride is exposed on the surface of the sprayed layer. When this seaweed reef substrate with the sprayed layer laid on its surface is placed on the seabed, nitrogen-fixing bacteria are initially induced and proliferated in the cotton-like bamboo fibers exposed on the surface of the sprayed layer and in the cotton-like bamboo fibers exposed in water due to voids (pores) created by the dissolution of granular sodium chloride on the surface. Nitrogen-fixing bacteria cannot penetrate much of the cotton-like bamboo fibers that are inside the sprayed layer and not exposed to water. Therefore, in the initial stages of installation, the effect of promoting nitrogen fixation, a nutrient, was limited, and the effect of promoting seaweed bed formation was also slow, which presented a problem.

[0008] Furthermore, the granular sodium chloride inside the sprayed layer dissolves into the water after the seaweed bed substrate is placed on the seabed, forming voids within the sprayed layer. However, if the granular sodium chloride is near the boundary between the sprayed layer and the substrate, voids are formed near the boundary, which reduces the adhesion between the sprayed layer and the substrate.

[0009] Therefore, the object of the present invention is to provide a method for manufacturing a water body structure, a spraying device used therefor, and a water body structure, which is installed by spraying the above-mentioned cotton-like bamboo fibers, which are a nitrogen-fixing bacteria induction and propagation material, onto the substrate surface of a seaweed bed reef, and which has a high effect in promoting the formation of seaweed beds in the initial stages of installation on the seabed and in which the sprayed layer is difficult to peel off from the substrate. [Means for solving the problem]

[0010] The first configuration of the method for manufacturing a structure for installation in a water body according to the present invention is a method for manufacturing a structure for installation in a water body that promotes the formation of seaweed beds in water, A base layer formation step involves forming a base layer by spraying a base layer spray material, which is a mixture of magnesium oxide, cotton-like bamboo fibers obtained by crushing and pulverizing raw bamboo rods so that the cell walls of the fiber cells rupture, and a bamboo fiber binder containing granular anhydrous magnesium chloride, with water or seawater, onto the surface of a substrate to be submerged in water. Before the base layer formed in the base layer formation step solidifies, The invention is characterized by comprising a surface layer formation step, in which a surface layer spray material containing the cotton-like bamboo fibers is sprayed onto the surface of the base layer to form a surface layer in which the surface layer spray material has penetrated into the surface area inside the base layer.

[0011] In this configuration, during the base layer formation process, a base layer spray material containing a bamboo fiber binder with magnesium oxide, cotton-like bamboo fibers, and anhydrous magnesium chloride mixed with water or seawater is sprayed onto the substrate surface, forming a base layer in which cotton-like bamboo fibers are mixed into the binder matrix of magnesium oxychloride (MOC) cement. Here, magnesium oxychloride cement (MOC cement, also called "Sorel cement") is a chemical cement formed by the reaction of magnesium oxide, anhydrous magnesium chloride, and water (or seawater) (see Non-Patent Literature 2, pp. 29-67). Immediately after spraying, the binder matrix is ​​in a gelled state in the initial setting process. Then, in the next surface layer formation process, a surface layer spray material containing cotton-like bamboo fibers is sprayed onto the surface of this base layer before it sets, forming a surface layer in which the surface layer spray material has penetrated into the base layer. As a result, the surface layer formed on the surface of the base layer has a large amount of cotton-like bamboo fibers exposed. In this state, when the binder matrix sets and hardens, the base layer is composed of an MOC binder matrix containing cotton-like bamboo fibers as a fiber reinforcement (cement filler), and the surface layer is composed of an MOC binder matrix containing cotton-like bamboo fibers embedded in the surface, forming a sprayed layer on the surface of the substrate. Because cotton-like bamboo fibers are mixed into the base layer, they function as a fiber reinforcement (cement filler), improving the resistance of the sprayed layer to cracking and chipping. In addition, since many cotton-like bamboo fibers are planted on the surface of the surface layer of the sprayed layer, nitrogen-fixing bacteria can easily penetrate into the cotton-like bamboo fibers in the initial stages of installation on the seabed, promoting the formation of seaweed beds in the initial stages of installation on the seabed.

[0012] Here, "substrate" refers to the supporting object (i.e., the base or foundation underneath) (see, for example, Non-Patent Document 1, Chapter 7, D5, "Provision of Substrate"). Generally, substrates used include stone, concrete, steel, FRP, and other base materials (masses, frames, scrapped ships, etc.) for seawalls, submerged structures, and artificial reefs.

[0013] The second configuration of the manufacturing method of the structure for underwater installation according to the present invention is that in the base layer forming step, and in the surface layer forming step, before the base layer formed in the base layer forming step is consolidated, spraying a surface layer spraying material containing the cotton-like bamboo fiber and granular sodium chloride onto the surface of the base layer to form a surface layer in a state where the surface layer spraying material has penetrated into the surface layer region inside the base layer is characterized in that.

[0014] According to this configuration, in the surface layer forming step, by spraying a surface layer spraying material containing cotton-like bamboo fiber and granular sodium chloride onto the surface of the base layer before it is consolidated, the surface layer formed on the surface of the base layer will have a state where a large amount of cotton-like bamboo fiber is exposed and granular sodium chloride is scattered. In this state, when the binder matrix coagulates and hardens, the base layer is composed of a MOC binder matrix containing cotton-like bamboo fiber as a fiber reinforcing material (cement filler), and the surface layer is a sprayed layer composed of a MOC binder matrix containing cotton-like bamboo fiber with cotton-like bamboo fiber and granular sodium chloride biting into the surface, which is formed on the surface of the substrate. Since there is no granular sodium chloride in the base layer of the sprayed layer, the problem that the adhesive force between the sprayed layer and the substrate decreases due to voids as described above does not occur. Also, a large amount of cotton-like bamboo fiber is implanted on the surface of the surface layer of the sprayed layer, and a large amount of granular sodium chloride is fitted in, so nitrogen-fixing bacteria can easily penetrate into the cotton-like bamboo fiber at the initial stage of installation underwater, and the formation of an algal bed at the initial stage of installation underwater is promoted. Also, after installation underwater, granular sodium chloride elutes into the water, and many voids opening to the surface are formed. The voids opening to the surface and the implanted cotton-like bamboo fiber capture the spores of algae floating in the water, making it easier for the algae to settle on the surface of the sprayed layer, and promoting the formation of an algal bed.

[0015] The second configuration of the manufacturing method of the structure for underwater installation according to the present invention is that in the base layer forming step, transporting the bamboo fiber-containing binder to the spraying nozzle by air transportation with an air flow discharged from an air compressor, and Water or seawater, pressurized by a water pump, is injected into the airflow containing the bamboo fiber binder at the base end of the spray nozzle, and the bamboo fiber binder and water or seawater are mixed inside the spray nozzle and sprayed onto the surface of the structure to be installed in the water area. In the initial surface layer formation process, The surface spraying material is characterized by being air-transported to the spraying nozzle by the airflow discharged from the air compressor and sprayed onto the surface of the structure to be installed in the water.

[0016] This configuration employs an "air gun spraying method," which involves carrying the spraying material (including bamboo fiber binder or surface spraying material) on an airflow discharged from an air compressor and spraying it onto the surface of a structure for water bodies as the base layer spraying material, rather than the "high-pressure spraying method," which involves directly pumping and spraying the base layer spraying material using a cement pump or similar device. This allows for optimal adjustment of the spraying pressure, reduces the amount of base layer spraying material scattered into the surrounding area, and improves the yield rate of the base layer spraying material during spraying. In other words, since structures for water bodies typically have hard surfaces such as concrete blocks, the sprayed base layer spraying material tends to bounce off. By adopting the "air gun spraying method," the loss rate of the base layer spraying material (the ratio of base layer spraying material that does not adhere to the base layer and scatters into the surrounding area to the amount of base layer spraying material used for spraying) can be significantly reduced. Furthermore, by adopting an air gun spraying method, the spray material does not pass through the pump, making it possible to smoothly spray even lightweight, fibrous spray materials such as bamboo fiber without clogging the flow path of the device. In addition, since the problem of spray material clogging is eliminated, there is no need to pump the spray material at high pressure, and the spray pressure can be adjusted in the low spray pressure range, reducing the amount of spray material scattered around during spraying.

[0017] A third configuration of the method for manufacturing a structure for installation in a water area according to the present invention is, in the first configuration, in the first configuration, before the base layer formation step, A mucus coating process in which an aqueous magnesium chloride solution is sprayed onto the surface of the substrate, thereby coating the surface of the substrate with the aqueous magnesium chloride solution. It is characterized by having the following features.

[0018] With this configuration, before the base layer spraying material is sprayed, the surface of the substrate is coated with a highly viscous magnesium chloride aqueous solution in the adhesive liquid coating process described above. As a result, the amount of base layer spraying material that does not adhere to the substrate surface and is repelled during spraying is reduced, the amount of base layer spraying material scattered into the surroundings is reduced, and the loss rate of base layer spraying material during spraying can be lowered.

[0019] A fourth configuration of the method for manufacturing a structure for installation in a water area according to the present invention is a base layer spray material receiving hopper that contains the bamboo fiber binder, in the first configuration, A surface spray material housing section for housing the aforementioned surface spray material, A water tank that contains water or seawater, An air compressor that discharges an airflow for pneumatically transporting the spray material, A spray material feeding device that feeds the spray material into the airflow discharged from the aforementioned air compressor, The spray material input device provides a means for switching between the bamboo fiber binder contained in the base layer spray material storage hopper and the surface layer spray material contained in the surface layer spray material storage section, and the spray material to be introduced into the airflow by the spray material input device. A spray nozzle that ejects the spray material, A spray hose connected to the airflow outlet of the spray material feeding device and the spray nozzle, A water pump for pumping water or seawater from the water tank, A water supply hose connected to the base end of the spray nozzle or to the spray hose and the discharge port of the water supply pump, A water cock is provided at the base end of the spray nozzle or at the water supply hose connection point, which is the connection point between the spray hose and the water supply hose, and is used to switch the flow of water or seawater injected from the water supply hose to the base end of the spray nozzle or the spray hose, Using a spraying device equipped with the following features, In the base layer formation step and the surface layer formation step, the spray material to be introduced into the airflow by the spray material input device is switched by the spray material input device using the spray material switching means of the spraying device to the bamboo fiber binder contained in the base layer spray material containment hopper or the surface layer spray material contained in the surface layer spray material containment section, thereby performing the spraying work on the surface of the substrate using the same spray nozzle. In the base layer formation process, the water cock is opened, and the base layer spraying material is sprayed while mixing the bamboo fiber binder with water or seawater in the section from the water supply hose connection to the discharge port of the spray nozzle. In the surface layer formation step, the water cock is closed and the spraying of the surface layer material is performed.

[0020] This configuration allows for switching of spray materials (switching between bamboo fiber binder and surface spray material) using a spray material switching mechanism, and enables the operator performing the spray to switch the water (or seawater) injection / stopping at their fingertips using a water cock near the spray nozzle. This makes it possible to switch spray materials easily and quickly at the manufacturing site, and in the surface layer formation process, it becomes possible to quickly spray the surface spray material onto the surface of the base layer before the base layer containing MOC cement formed in the base layer formation process hardens.

[0021] A fifth configuration of the method for manufacturing a structure for installation in a water area according to the present invention is that, in the fourth configuration, the spraying device is A mucus tank containing a magnesium chloride aqueous solution, A mucus pump for pumping the magnesium chloride aqueous solution in the mucus tank, A mucus hose connected to the base end of the spray nozzle or to the spray hose and the discharge port of the mucus pump, A mucus cock is provided at the base end of the spray nozzle or at the mucus hose connection point, which is the connection point between the spray hose and the mucus hose, and is used to switch the flow of magnesium chloride aqueous solution injected from the mucus hose to the base end of the spray nozzle or the spray hose, It is equipped with, Before the aforementioned base layer formation step, The process includes a viscous coating step in which an aqueous magnesium chloride solution is applied to the surface of the substrate by spraying it onto the substrate surface, In the aforementioned mucus application process, the spray material input device is stopped, and while an airflow is discharged from the air compressor, the mucus cock is opened, and the magnesium chloride aqueous solution, which is pumped from the mucus tank by the mucus pump, is sprayed onto the base layer spray material using the spray nozzle.

[0022] This configuration allows the operator performing the spray to switch between spraying and stopping the adhesive liquid (magnesium chloride aqueous solution) at their fingertips using a mucus cock near the spray nozzle. This makes it possible to easily switch between spraying magnesium chloride aqueous solution onto the substrate surface using the same spraying device during the mucus coating process, simplifying the manufacturing process and improving work efficiency.

[0023] A sixth configuration of the method for manufacturing a structure for installation in a body of water according to the present invention is that, in the first configuration, a granular porous glassy algae growth material is added to the surface spray material, which releases divalent iron ions into the water when immersed in water. It is characterized by the following.

[0024] According to this configuration, a porous glassy algae growth material is embedded in the surface layer of the manufactured aquatic structure, with the material exposed on the surface. This makes it possible to manufacture aquatic structures that are highly effective in promoting algae bed formation after being submerged in water.

[0025] Here, as the "porous glass algae growth material," for example, the "porous glass algae growth material" described in Patent Document 2 and Patent Document 3 can be used. Specifically, for example, a glass material containing FeO and / or Fe2O3 (SiO2: 15~50w%, Na2O and / or K2O: 1~35w%, B2O3: 30~70w%) formed into a porous structure with closed cells can be used as a "granular porous glass algae growth material that releases divalent iron ions into water."

[0026] A seventh configuration of the method for manufacturing a structure for installation in a body of water according to the present invention is that, in the first configuration, in the base layer formation step, the bamboo fiber binder is sprayed onto the surface of a substrate to be submerged in water as a base layer spraying material, which is a mixture of water or seawater and citric acid. It is characterized by the following.

[0027] With this configuration, mixing citric acid with the base layer spray material slows down the setting rate of the MOC cement, making it easier for the surface layer spray material to adhere during the surface layer formation process.

[0028] The first configuration of the spraying apparatus according to the present invention comprises a base layer spraying material receiving hopper that contains the bamboo fiber binder, A surface spray material housing section for housing the aforementioned surface spray material, A water tank that contains water or seawater, An air compressor that discharges an airflow for pneumatically transporting the spray material, A spray material feeding device that feeds the spray material into the airflow discharged from the aforementioned air compressor, The spray material input device provides a means for switching between the bamboo fiber binder contained in the base layer spray material storage hopper and the surface layer spray material contained in the surface layer spray material storage section, and the spray material to be introduced into the airflow by the spray material input device. A spray nozzle that ejects the spray material, A spray hose connected to the airflow outlet of the spray material feeding device and the spray nozzle, A water pump for pumping water or seawater from the water tank, A water supply hose connected to the base end of the spray nozzle or to the spray hose and the discharge port of the water supply pump, A water cock is provided at the base end of the spray nozzle or at the water supply hose connection point, which is the connection point between the spray hose and the water supply hose, and is used to switch the flow of water or seawater injected from the water supply hose to the base end of the spray nozzle or the spray hose, It is characterized by having the following features.

[0029] A second configuration of the spraying apparatus according to the present invention is that, in the first configuration, the spraying apparatus is A mucus tank containing a magnesium chloride aqueous solution, A mucus pump for pumping the magnesium chloride aqueous solution in the mucus tank, A mucus hose connected to the base end of the spray nozzle or to the spray hose and the discharge port of the mucus pump, A mucus cock is provided at the base end of the spray nozzle or at the mucus hose connection point, which is the connection point between the spray hose and the mucus hose, and is used to switch the flow of magnesium chloride aqueous solution injected from the mucus hose to the base end of the spray nozzle or the spray hose, It is characterized by having the following features.

[0030] The first configuration of the aquatic structure according to the present invention is an aquatic structure that is submerged on the seabed to promote the formation of seaweed beds in water, A base layer is formed by mixing a bamboo fiber binder containing magnesium oxide, cotton-like bamboo fibers obtained by crushing and grinding raw bamboo rods so that the cell walls of the fiber cells cleave, and granular anhydrous magnesium chloride with water or seawater and hardening it, which is formed on the surface of the substrate. The base layer comprises a surface layer formed on the surface of the base layer, in which the cotton-like bamboo fibers are embedded and fixed to the surface layer region inside the base layer. A characteristic feature is that a portion of the cotton-like bamboo fibers in the surface layer are exposed on the surface of the surface layer.

[0031] Furthermore, the second configuration of the water body structure according to the present invention is characterized in that, in the first configuration, granular sodium chloride is scattered in the surface layer, and a portion of the surface of the granular sodium chloride is exposed on the surface of the surface layer. [Effects of the Invention]

[0032] As described above, the present invention provides a method for manufacturing a water body structure in which the above-mentioned cotton-like bamboo fibers, which are used as an inducer and propagator for nitrogen-fixing bacteria in water, are sprayed onto the substrate surface of a seaweed bed reef, and which have a high effect in promoting the formation of seaweed beds in the initial stages of installation on the seabed, and in which the sprayed layer is difficult to peel off from the substrate, as well as a spraying device used therefor and a water body structure. [Brief explanation of the drawing]

[0033] [Figure 1] (a) Raw materials for cotton-like bamboo fibers used in the manufacturing method of the water body structure of the present invention, (b) the manufacturing process of cotton-like bamboo fibers, and (c) a photograph of the appearance of cotton-like bamboo fibers. [Figure 2] This is an electron microscope image of cotton-like bamboo fibers. [Figure 3] This figure shows the overall configuration of the spraying device used in the manufacturing method of a water body structure according to Example 1 of the present invention. [Figure 4] This figure shows an example of the spray material input device 7 of the spraying device 1 shown in Figure 3. [Figure 5] This figure shows an example of the area around the spray nozzle 9 of the spraying device 1 shown in Figure 3. [Figure 6] This diagram shows the process for manufacturing the water body structure according to the present invention. [Figure 7] This is a magnified photograph of the surface of the sprayed layer of a water body structure manufactured by the manufacturing method of the present invention. [Figure 8] This figure shows the state of voids on the surface of the sprayed layer after granular sodium chloride has dissolved from being placed in water. [Figure 9] This figure shows the surface condition of a structure for installation in a body of water after a sprayed layer has been formed on the surface of the substrate and then left outdoors for one month. [Figure 10] These are photographs showing the progress of aquatic plant attachment on the surface of each specimen. [Figure 11] This graph shows the results of measuring the change in the maximum total length of Sargassum species attached to the surface of each test specimen. [Figure 12] This is a photograph of the X block (test block) immediately after spraying, which was used to form the test and control sections. [Figure 13] This is an external photograph showing the condition of the test block six months after it was sunk to the seabed. [Figure 14] This is an external photograph showing the condition of the test block 1 year and 7 months after it was sunk to the seabed. [Modes for carrying out the invention]

[0034] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. [Examples]

[0035] (1) Cotton-like bamboo fiber Figure 1 shows (a) the raw material for cotton-like bamboo fiber used in the manufacturing method of the aquatic structure of the present invention, (b) the manufacturing process of cotton-like bamboo fiber, and (c) a photograph of the appearance of cotton-like bamboo fiber. In this specification, "cotton-like bamboo fiber" refers to a cotton-like bamboo fiber material obtained by crushing and pulverizing raw bamboo rods so that the cell walls of the fiber cells split (see Figure 1(c)). This cotton-like bamboo fiber is manufactured by crushing raw bamboo (see Figure 1(a)) with a twin-screw crusher until the cell walls split, and then tearing it with a cutter blade at the outlet of the twin-screw crusher (see Figure 1(b)). As shown in Figure 1(c), this cotton-like bamboo fiber is in a state where the bamboo fibers are intertwined like cotton.

[0036] Figure 2 shows an electron microscope image of the cotton-like bamboo fibers used in the present invention. As shown in Figure 2, the cotton-like bamboo fibers are in a state where each individual bamboo fiber has been broken down and the cell walls of the bamboo fibers have been split open. When these cotton-like bamboo fibers are scattered in nature, nitrogen-fixing bacteria proliferate within the cell walls of the bamboo fibers, and nitrogen from the air and water is fixed inside the cotton-like bamboo fibers (see Japanese Patent Publication No. 2010-070963).

[0037] (2) Spraying device Figure 3 shows the overall configuration of a spraying device used in a method for manufacturing a structure for installation in a water area according to Embodiment 1 of the present invention. The spraying device 1 comprises a base layer spraying material storage section 2, a surface layer spraying material storage section 3, a water tank 4, a mucus tank 5, an air compressor 6, a spraying material input device 7, an input spraying material switching means 8, a spraying nozzle 9, a spraying hose 10, a water supply pump 11, a water supply hose 12, a water cock 14, a mucus pump 15, a mucus hose 16, and a mucus cock 18.

[0038] The base layer spray material storage section 2 is a storage container for the bamboo fiber binder. The "bamboo fiber binder" refers to a binder material containing magnesium oxide (MgO), cotton-like bamboo fibers, and granular anhydrous magnesium chloride (MgCl2). The bamboo fiber binder does not contain water and has a dry state. Anhydrous magnesium chloride is nearly 100% magnesium chloride that does not contain water and does not hold water in its crystal structure. The surface layer spray material storage section 3 is a storage container for the surface layer spray material. The "surface layer spray material" refers to a spray material containing cotton-like bamboo fibers and granular sodium chloride. In Figure 3, the base layer spray material storage section 2 and the surface layer spray material storage section 3 are shown as "hoppers," but instead of hoppers, "flexible container bags" can also be used for the base layer spray material storage section 2 and the surface layer spray material storage section 3. Using flexible container bags makes transportation and storage easier. Furthermore, when the spray material inside the container runs out, it can be simply replaced with another flexible container filled to capacity, thus improving work efficiency.

[0039] Water tank 4 is a tank for storing water or seawater. When citric acid is used as a setting retarder for magnesia cement, water and citric acid are mixed and stored in water tank 4. Mucus tank 5 is a tank for storing an aqueous magnesium chloride solution. The aqueous magnesium chloride solution is more viscous than water or seawater and is used as a viscous adhesive (mucus) during spraying in this invention.

[0040] The air compressor 6 is a compressor (air compressor) that discharges an airflow for air transport of the spray material. The spray material feeding device 7 is a mixing device that feeds the spray material supplied from the base layer spray material storage section 2 or the surface layer spray material storage section 3 into the airflow discharged from the air compressor 6. The spray material feeding device 7 is equipped with a feeding hopper 7a for feeding the spray material, an air supply port 7b into which the airflow pressurized from the air compressor 6 flows, and a discharge port 7c for discharging the airflow into which the spray material has been fed and mixed. The spray material feeding device 7 can also stop feeding the spray material into the airflow, and when feeding is stopped, only compressed air is discharged from the discharge port 7c of the spray material feeding device 7. The feeding spray material switching means 8 is a device that switches the supply path of the spray material supplied to the spray material feeding device 7 between the base layer spray material storage section 2 or the surface layer spray material storage section 3. The spray material input switching means 8 switches between the bamboo fiber binder contained in the base layer spray material storage section 2 and the surface layer spray material contained in the surface layer spray material storage section 3, which are then introduced into the airflow by the spray material input device 7.

[0041] The spray nozzle 9 is a nozzle that ejects the spray material. The spray hose 10 is a hose that connects the discharge port 7c of the airflow (airflow mixed with the spray material) of the spray material input device 7 to the spray nozzle 9.

[0042] The water supply pump 11 is a pump that pressurizes and pumps water or seawater from the water tank 4. The water supply hose 12 is a hose connected to the discharge port of the water pump 11 and the base end of the spray nozzle 9 (or near the downstream end of the spray hose 10). The water cock 14 is provided at the connection point (water supply hose connection point 12a) between the water supply hose 12 and the base end of the spray nozzle 9 (or the spray hose 12), and is a valve that switches the flow of water or seawater injected from the water supply hose 12 to the base end of the spray nozzle 9 (or the spray hose 12).

[0043] The mucus pump 15 is a pump that pumps the magnesium chloride aqueous solution in the mucus tank 5. The mucus hose 16 is a hose connected to the discharge port of the mucus pump 15 and the base end of the spray nozzle 9 (or near the downstream end of the spray hose 10). The mucus cock 18 is provided at the connection point (mucus hose connection point 16a) between the mucus hose 16 and the base end of the spray nozzle 9 (or the spray hose 10), and is a valve that switches the flow of the magnesium chloride aqueous solution injected from the mucus hose 16 to the base end of the spray nozzle 9 (or the spray hose 10).

[0044] Thus, in the spraying apparatus 1 of this embodiment, the input spraying material switching means 8 enables switching of the spraying material (switching between bamboo fiber binder and surface layer spraying material), and the water cock 14 and mucus cock 18 near the spraying nozzle 9 allow the operator performing the spraying to switch the spraying / stopping of water (or seawater) and the spraying / stopping of the adhesive liquid (magnesium chloride aqueous solution) at their fingertips, making it possible to switch spraying materials easily and quickly at the manufacturing site. In particular, in the surface layer formation process, it is necessary to spray the surface layer spraying material onto the surface of the base layer before the base layer containing MOC cement formed in the base layer formation process hardens (i.e., during the induction period (latent period) before the hardening (acceleration) of the MOC cement begins), so it is important to be able to switch spraying materials easily and quickly.

[0045] (2.1) Spray material feeding device Figure 4 shows an example of the spray material feeding device 7 of the spraying device 1 in Figure 3. Figure 4(a) is an overall view, and Figure 4(b) is a perspective view of the area around the feeding hopper 7a of the spray material feeding device 7 in Figure 4(a). The spray material feeding device 7 comprises a feeding hopper 7a, an air supply port 7b, a discharge port 7c, a feeding pipe 7d, a mixing channel 7e, a stirring shaft 7f, a stirring blade 7g, a drive motor 7h, and a belt transmission mechanism 7i. The feeding hopper 7a is a frustoconical hopper for feeding the spray material, located at the top of the spray material feeding device 7. The air supply port 7b is a port for supplying compressed air discharged from the air compressor 6, the discharge port 7c is a port for discharging air mixed with the spray material, and the mixing channel 7e is a channel provided horizontally in an arc shape at the bottom of the feeding hopper 7a, connecting the air supply port 7b and the discharge port 7c. The input pipe 7d is a pipe that drops the spray material into the airflow from the bottom of the input hopper 7a. The stirring shaft 7f is a shaft that is rotatably mounted along the central axis of the input hopper 7a, and the stirring blade 7g is a blade mounted inside the input hopper 7a on the stirring shaft 7f. The drive motor 7h is a motor that rotates the stirring shaft 7f, and the belt transmission mechanism 7i is a belt mechanism that transmits the rotational power of the drive motor 7h to the stirring shaft 7f.

[0046] The airflow supplied from the air supply port 7b enters the mixing channel 7e, swirls, and is then discharged from the discharge port 7c. Meanwhile, the spray material fed into the input hopper 7a is agitated within the input hopper 7a by the stirring blades 7g and fed from above into the mixing channel 7e via the input pipe 7d. In the mixing channel 7e, the spray material is mixed with the swirling airflow, and the airflow of suspended gas mixed with the spray material is discharged from the discharge port 7c. Furthermore, when the drive motor 7h is stopped, the feeding of the spray material from the input hopper 7a to the input pipe 7d stops, and only air without the spray material is discharged from the discharge port 7c.

[0047] Thus, in this specification, a spraying method in which the spraying material is sprayed by carrying it on the airflow of compressed air from an air compressor 6, rather than the "high-pressure spraying method" in which the spraying material in the spraying material storage hopper is directly pumped by a pump, is called the "air gun spraying method." As the spraying material feeding device 7 used in such an air gun spraying method, a dust-suppressing refractory gun (for example, a dust-suppressing SRG manufactured by Shinagawa Refractories Co., Ltd.) used for lining in blast furnaces or spraying cement in tunnels can be used.

[0048] In this embodiment, the spraying device 1 employs this air gun spraying method, which allows for smooth spraying of lightweight, fibrous materials such as bamboo fiber without clogging the device's flow path. In other words, in high-pressure spraying methods, where the spraying material is directly pumped, a high-output pump is required to prevent fibrous materials from clogging the pump, inevitably leading to a larger spraying device and higher spraying pressure. In contrast, with the air gun spraying method, the spraying material does not pass through the pump, eliminating the problem of fibrous materials clogging the pump (or a filter located before the pump in the case of a small pump) (referred to as the "spraying material clogging problem"). Furthermore, because the spraying material clogging problem is eliminated, it becomes possible to use a small air compressor 6 and a spraying material feeding device 7. Furthermore, since the problem of clogging of the spray material is eliminated, there is no need to pump the spray material at high pressure, and the spray pressure can be adjusted in the low spray pressure range, reducing the amount of spray material scattered around during spraying.

[0049] Furthermore, by employing an air gun spraying method in the spraying device 1 of this embodiment, a high-pressure pump for directly pumping the spraying material is unnecessary, and the device can be constructed with a small air compressor 6 and a spraying material feeding device 7, which has the advantage of making the spraying device 1 easy to transport. Rough estimates show that the weight of each component is approximately 0.5t for the spraying material feeding device 7, 1t for the generator for supplying power to each device, 1.5t for the air compressor 6, and 0.2t for each hopper and dust collector (used to prevent dust from scattering into the surroundings), so the total weight will be within 5t, making it quite possible to transport the spraying device 1 in a 5t truck. Typically, the substrates for structures installed in water bodies (tetrapods, blocks, stones, steel members, etc.) are very heavy to prevent them from being swept away by ocean currents, and the actual manufacturing of these structures is mostly carried out not in a factory, but in an outdoor yard near the installation site where the substrates are temporarily stored. Therefore, from the perspective of on-site workability, the ability to transport the spraying device 1 by a 5-ton truck is a significant advantage.

[0050] (2.2) Spray nozzle Figure 5 shows an example of the area around the spray nozzle 9 of the spraying device 1 shown in Figure 3. In the example in Figure 5, the water supply hose connection part 12a and the mucus hose connection part 16a are located at the same place. A branch pipe 19 that branches in a Y shape is connected to the side of the base end of the spray nozzle 9. The water supply hose 12 is connected to one branch 19a of the branch pipe 19, and the mucus hose 16 is connected to the other branch 19b. A water cock 14 is provided at the connection point between branch 19a of the branch pipe 19 and the water supply hose 12, and a mucus cock 18 is provided at the connection point between branch 19b of the branch pipe 19 and the mucus hose 16. Since the water cock 14 and the mucus cock 18 are located near the spray nozzle 9, the operator performing the spraying work can operate the water cock 14 and the mucus cock 18 at the same time as the spray nozzle 9 to turn the water or seawater on and off, and the magnesium chloride aqueous solution on and off. Furthermore, to ensure thorough mixing of the bamboo fiber binder with water or seawater, the length of the spray nozzle 9 can be increased to approximately 1.5 to 2 meters. Additionally, the branch pipe 19 can be configured to connect to the spray hose 10 near the spray nozzle 9.

[0051] (3) Sprayed material (3.1) Bamboo fiber binder The bamboo fiber binder used in the manufacturing method of the aquatic structure according to this embodiment consists of aggregate, magnesium oxide (MgO), cotton-like bamboo fibers, and granular anhydrous magnesium chloride (MgCl2). The aggregate can be sand (sea sand), decomposed granite, clinker, etc. The mixing ratio of each component material is, for example, as follows:

[0052] [Table 1]

[0053] (3.2) Surface spray material The surface spray material used in the manufacturing method of the structure for installation in a water area according to this embodiment consists of cotton-like bamboo fibers and granular sodium chloride. The mixing ratio of each constituent material can be, for example, as shown in the table below.

[0054] [Table 2]

[0055] Here, "granular sodium chloride" refers to sodium chloride that has been processed into granules. Granular sodium chloride is generally commercially available for industrial and road maintenance applications, such as de-icing agents, snow melting agents, water softeners for boilers, and dust suppressants. In this invention, there are no particular limitations on the particle size of the granular sodium chloride, but from the viewpoint of ease of mechanical spraying, it is preferable to use particles with a particle size (equivalent diameter of a sphere) of about 0.5 to 6.0 mm.

[0056] Furthermore, depending on the body of water where the structures for installation in the water are to be submerged, divalent iron (Fe) may be present as nutrients. 2+ In some cases, there may be a deficiency of (see Non-Patent Documents 3 and 4), in which case porous glass algae growth material is added. In that case, the mixing ratio of each component material of the surface spray material can be, for example, as shown in the table below.

[0057] [Table 3]

[0058] Furthermore, when coloring the surface of structures installed in water bodies with environmental considerations in mind, an appropriate amount of powdered ferrous sulfate can be added to the surface spray material.

[0059] Furthermore, in situations where there is little benefit in forming voids in the surface layer, such as in still water areas with little water flow, like lakes and reservoirs, the addition of granular sodium chloride to the surface spray material can be omitted to reduce manufacturing costs, and the surface spray material can consist only of cotton-like bamboo fibers.

[0060] (4) Manufacturing method of structures for installation in water areas Figure 6 shows the flow of the manufacturing method for the water body structure according to the present invention. In the manufacturing method for the water body structure according to this embodiment, as shown in Figure 6(S0), the manufacturing work is carried out by two workers: worker P1 who performs the spraying work and worker P2 who operates the spray material input device 7 and the input spray material switching means 8.

[0061] (S1) Mucus application process First, a magnesium chloride aqueous solution is sprayed onto the surface of the substrate to be submerged in water (see Figure 6(S1)). At this time, with the spray material input device 7 stopped, the air compressor 6 is started to allow compressed air to flow through the spray hose 10. The worker P1 performing the spraying closes the water cock 14 and opens the mucus cock 18 to spray the magnesium chloride aqueous solution from the spray nozzle 9. The concentration of the magnesium chloride aqueous solution sprayed at this time is preferably 10-20 w%. If the concentration is greater than 20 w% the viscosity of the aqueous solution is too high, magnesium chloride will adhere to and solidify inside the mucus pump 15 and mucus hose 16 during and after the work, causing clogging, and will also adversely affect the phase composition (ratio of phase 3 to phase 5) of the magnesium oxychloride cement in the base layer formed in the subsequent base layer formation process (see Non-Patent Literature 2, pp. 30-35). Furthermore, if the concentration is less than 10 w%, the adhesive strength is too low, and when the base layer spray material is sprayed during the subsequent base layer formation process, a large amount of the base layer spray material will not adhere to the substrate surface and will be repelled and scattered into the surrounding area.

[0062] (S2) Base layer formation process Next, the base layer spray material is sprayed onto the surface of the substrate to be submerged in water to form the base layer (see Figure 6(S2)). In this step, the air compressor 6 is started to allow compressed air to flow through the spray hose 10, and the input spray material switching means 8 is switched so that the bamboo fiber binder is fed from the base layer spray material storage section 2 to the input hopper 7a of the spray material input device 7. The spray material input device 7 is then started to mix the bamboo fiber binder with the compressed air and spray it, while the worker P1 performing the spraying opens the water cock 14 and closes the mucus cock 18, injecting water or seawater from the water tank 4 into the spray nozzle 9 through which the airflow of suspended gas mixed with the bamboo fiber binder flows, and spraying the base layer spray material mixed with water or seawater from the tip of the spray nozzle 9 onto the surface of the substrate. As a result, a base layer is formed on the surface of the substrate.

[0063] Since the substrate surface is coated with a highly viscous magnesium chloride aqueous solution during the adhesive liquid coating process described above, the amount of base layer spray material that does not adhere to the substrate surface and is repelled during spraying is reduced, the amount of base layer spray material scattered into the surroundings is reduced, and the yield rate of the base layer spray material during spraying (the ratio of base layer spray material adhering to the base layer to the amount of base layer spray material used for spraying) is improved.

[0064] Furthermore, the magnesium chloride aqueous solution applied to the substrate surface in advance wets the substrate surface and penetrates into the microscopic depressions and interior of the substrate surface. When the base layer spray material is sprayed onto this surface, the penetrated magnesium chloride aqueous solution reacts with the magnesium oxide contained in the base layer spray material to form magnesium oxychloride (MOC), which adheres tightly to the substrate surface as an MOC cement matrix, further enhancing the adhesion between substrates.

[0065] Furthermore, instead of "high-pressure spraying," which involves directly pumping and spraying the base layer spray material using a cement pump, the "gun spraying" method was adopted. This method involves placing the bamboo fiber binder on the compressed air stream from the air compressor 6, mixing the water and bamboo fiber binder near the spraying nozzle, and then spraying it as the base layer spray material. This allows for optimal adjustment of the spraying pressure, reduces the amount of base layer spray material scattered into the surroundings, and improves the yield rate of the base layer spray material during spraying. In particular, since the substrate is generally a hard surface such as a concrete block, the sprayed base layer spray material is prone to bouncing off, and the reduction in the loss rate (the ratio of base layer spray material that does not adhere to the base layer and is scattered into the surroundings to the amount of base layer spray material used for spraying) by adopting "gun spraying" is significant. Actual spraying tests confirmed that the loss rate was approximately 200% with "high-pressure spraying," while it was reduced to approximately 30% with "gun spraying."

[0066] (S3) Surface layer formation process Next, before the base layer formed in the base layer formation process (S2) solidifies (during the induction period (latent period) before the setting of the MOC cement begins), a surface layer spray material is sprayed onto the surface of the base layer to form a surface layer in which the surface layer spray material has penetrated into the surface area inside the base layer (see Figure 6 (S3)). In this process, the air compressor 6 is started to allow compressed air to flow through the spray hose 10, and the input spray material switching means 8 is switched so that the surface layer spray material is fed from the surface layer spray material storage section 2 to the input hopper 7a of the spray material input device 7. Then, the spray material input device 7 is activated, and the surface spray material is mixed with the compressed air airflow and sprayed. At the same time, the worker P1 performing the spraying closes the water cock 14 and the mucus cock 18 at his fingertips, causing the surface spray material to be sprayed from the tip of the spray nozzle 9 onto the surface of the unsolidified base layer. As a result, a surface layer is formed in the surface area of ​​the base layer.

[0067] In this surface layer formation process (S3), the switching of the sprayed material can be done quickly from the base layer formation process (S2) simply by switching the sprayed material by worker P2 and opening and closing the water cock 14 by worker P1. Therefore, the surface layer sprayed material can be sprayed onto the base layer surface at an early stage, before the fluidity of the MOC cement decreases immediately after spraying. This allows the surface layer sprayed material, which contains cotton-like bamboo fibers and granular sodium chloride (and / or porous glassy algae growth material), to be deeply embedded in the base layer surface, suppressing the peeling off of the surface layer sprayed material after the MOC cement hardens. In addition, the surface layer will have cotton-like bamboo fibers planted and fixed to its surface, and numerous granular sodium chloride exposed on the surface will be embedded and scattered in various places on the surface.

[0068] Here, granular sodium chloride, compared to other alkali metal chlorides such as granular calcium chloride and granular magnesium chloride, is not hygroscopic and takes a relatively long time to dissolve in water. Therefore, it remains in a solid state and maintains its shape even after the MOC cement matrix has hardened.

[0069] In the above surface layer formation step (S3), the worker S2 closed the water cock 14 and the mucus cock 18 before spraying. However, in this surface layer formation step (S3), the worker S2 may also open the water cock 14 or the mucus cock 18 to mix an appropriate amount of water or magnesium chloride aqueous solution with the surface layer spray material before spraying. This helps to prevent the surface layer spray material from scattering into the surrounding area. However, if too much water is added to the surface layer spray material, the granular sodium chloride may dissolve or the base layer spray material that has not yet solidified may flow off. Therefore, the amount of water (or seawater) or magnesium chloride aqueous solution added should be small enough (just enough to moisten the surface layer spray material) so that the previously sprayed base layer spray material does not flow off and the granular sodium chloride does not dissolve significantly. Furthermore, since magnesium chloride aqueous solution is particularly viscous than water, even a small amount is highly effective in suppressing the scattering of the surface spray material. Therefore, in the surface layer formation step (S3), it is preferable to close the water cock 14 and open the viscosity cock 18 to mix a small amount of magnesium chloride aqueous solution with the surface spray material before spraying.

[0070] (5) Structures to be manufactured for installation in water areas Figure 7 is a magnified photograph of the surface of a sprayed layer of a water body structure manufactured by the manufacturing method of the present invention. Figure 7(a) shows the case when the surface sprayed material in Table 2 is used, and Figure 7(b) shows the case when the surface sprayed material in Table 3 is used. On the surface of the sprayed layer, the cotton-like bamboo fibers sprayed as the surface sprayed material penetrate into the surface layer of the base layer and are fixed in place, with some of these cotton-like bamboo fibers exposed on the surface of the surface layer. In addition, the granular sodium chloride contained in the surface sprayed material is dispersed (penetrated) into the MOC cement matrix, with some of it exposed on the surface. Furthermore, when the surface sprayed material in Table 3 is used, as shown in Figure 7(b), the porous glassy algae growth material contained in the surface sprayed material is dispersed into the MOC cement matrix, with some of it exposed on the surface.

[0071] When this structure for installation in water is submerged, the granular sodium chloride exposed on the surface first dissolves, and voids (holes) are formed in the areas where the granular sodium chloride was embedded. Figure 8 shows the state of the voids on the surface of the sprayed layer after the granular sodium chloride has dissolved after being placed in water. Figure 8(a) shows the case when the surface spray material in Table 2 is used, and Figure 8(b) shows the case when the surface spray material in Table 3 is used. Note that Figure 8 is a surface photograph of a test piece prepared for the experiment. Figure 9 shows the surface state of the structure for installation in water after the sprayed layer has been formed on the surface of a substrate that will actually be submerged in water, and then left outdoors for one month.

[0072] Granular sodium chloride dissolves in water within a few days, and depression-like voids are formed in the areas where the granular sodium chloride was embedded, as shown in Figure 8(b). In an experiment where a sprayed layer was formed on the surface of a substrate actually used in seaweed reefs according to the manufacturing method of the present invention, and then left in an outdoor environment on land for about a month, the granular sodium chloride dissolved due to rainfall during the period of storage, and a surface structure with numerous irregularities (voids) was formed as shown in Figure 9. The same thing happens when the substrate is submerged in water, as confirmed in the experiment in Figure 8.

[0073] Furthermore, the cotton-like bamboo fibers attached to the surface, some of which are embedded within the MOC cement matrix, will not be washed away in water. Because they are exposed on the surface, nitrogen-fixing bacteria floating in the water can easily enter the interior, and the nitrogen-fixing bacteria that enter the interior proliferate and fix nitrogen, a nutrient. In addition, the surface where the cotton-like bamboo fibers are planted captures the spores of algae floating in the water, promoting algal colonization. Moreover, the surface where the cotton-like bamboo fibers are planted and which has many irregularities due to voids also becomes a habitat for small aquatic animals such as shellfish and annelids (such as polychaetes), and the fertilizing effect of the waste products excreted by these small aquatic animals further promotes algal colonization.

[0074] (5.1) Role of the subsoil and surface layer in seaweed bed formation in the present invention In the aquatic structure manufactured according to the present invention, the sprayed layer formed on the substrate surface has a two-layer structure: a "base layer" formed by spraying a base layer sprayed material, which is a mixture of a bamboo fiber binder containing magnesium oxide, cotton-like bamboo fibers, and granular anhydrous magnesium chloride, with water or seawater; and a "surface layer" formed by spraying a surface layer sprayed material containing cotton-like bamboo fibers (and / or granular sodium chloride) onto the surface (surface layer area) of the "base layer". In this two-layer structure, the "base layer" primarily firmly adheres and fixes (firmly supports) the entire sprayed layer to the substrate surface, and also plays a role in inducing aquatic microorganisms and producing, fixing, and accumulating nutrients necessary for seaweed bed formation, such as nitrogen fixation in water. On the other hand, the "surface layer," like the base layer, produces, fixes, and accumulates nutrients necessary for seaweed bed formation, and also plays a role in capturing seaweed spores floating in the water and preventing the loss of germinated seaweed. The cottony bamboo fibers exposed on the surface and the voids formed after the granular sodium chloride dissolves play a significant role in capturing and preventing the loss of seaweed spores. Unlike ordinary wood fibers such as cedar and cypress, which quickly decompose and disappear in water, bamboo fibers are relatively resistant to decay and maintain their effectiveness in capturing and preventing the loss of spores over a long period of time.

[0075] When this aquatic structure is installed on the seabed, seaweed spores floating in the water are first captured and germinate in the surface layer. If the surface of the substrate is smooth, spores are less likely to be captured and the rate of seaweed attachment is low. However, in the aquatic structure used as a substrate in this invention, the cotton-like bamboo fibers exposed on the surface and the irregularities of the voids opening on the surface allow for efficient spore capture, thus improving the rate of seaweed attachment. To further improve this spore capture effect, it is effective to use as much cotton-like bamboo fiber as possible that is adhered to the surface layer, and to spray the cotton-like bamboo fiber on the surface layer in a way that makes the surface as fuzzy as possible (more precisely, so that the surface of the surface layer is flocked with cotton-like bamboo fiber).

[0076] Next, once the seaweed has settled and germinated, it grows, utilizing nutrients produced and fixed by aquatic microorganisms in the surface and subsoil layers. This promotes efficient seaweed bed formation.

[0077] Compared to substrates used in conventional seaweed bed formation technologies, the present invention is characterized by its ability to further improve and maintain the capture effect of water-borne planktonic spores on the substrate surface for a long period of time by using fine bamboo fibers and voids that are resistant to corrosion, thereby improving the rate of seaweed establishment.

[0078] (6) Results of the test on the effect of promoting seaweed bed formation Next, we will describe the results of verification tests regarding the effect of the aquatic structure manufactured by the manufacturing method of the present invention on promoting seaweed bed formation.

[0079] (6.1) Test Method [1] First, prepare several substrate concrete plates of the same size.

[0080] [2] Next, prepare the base layer spray material and the surface layer spray material. Here, the base layer spray material will be formulated as follows: (Composition A) Cotton-like bamboo fiber 7.4 wt%, granular anhydrous magnesium chloride 18.6 wt%, sand aggregate 74.0 wt% (Formulation B) Cotton-like bamboo fiber 4.3 wt%, granular anhydrous magnesium chloride 13.5 wt%, sand aggregate 82.2 wt% Furthermore, only cotton-like bamboo fibers were used as the surface spraying material (granular sodium chloride was not used in this test).

[0081] [3] Using the above-mentioned substrate concrete plate, the following three types of test specimens are prepared. (i) Control specimens A substrate concrete plate with no spray coating applied. (ii) Test specimen A A concrete plate formed by spraying a base layer and a surface layer using a base layer spray material of formulation A mixed with an appropriate amount of water and a surface layer spray material of cotton-like bamboo fibers, according to the manufacturing method of the present invention. (iii) Test specimen B A concrete plate formed by spraying a base layer and a surface layer using a base layer spray material of formulation B mixed with an appropriate amount of water and a surface layer spray material of cotton-like bamboo fibers, according to the manufacturing method of the present invention.

[0082] [4] The specimens described in (i) to (iii) above were placed side by side on the seabed of the test area, and the state of aquatic plant attachment on the surface of each specimen was observed for 300 days. The test area was a sea area inhabited by Sargassum species (within Iki-Oshima Fishing Port, Iki City, Nagasaki Prefecture).

[0083] (6.2) Test results Figure 10 is a photograph showing the progression of aquatic plant attachment on the surface of each specimen. Figure 11 is a graph showing the results of measuring the maximum total length of Sargassum species attached to the surface of each specimen. During observation, the specimens were pulled out of the water for photography and measurement of the attached seaweed plants, and then returned to their original positions. Since the growth period of Sargassum species attached to the surface of the specimens differs from individual to individual, the maximum total length of the fastest-growing plant was measured.

[0084] Figures 10 and 11 show that the growth of seaweed attached to test specimens A and B was faster than that of the control specimens. Visually, test specimen A had the highest density of attached seaweed, and the growth rate of the attached seaweed was the fastest. This indicates that using the aquatic structure manufactured by the present invention promotes the attachment of seaweed to the surface of the substrate concrete plate in the water area where it is laid, and also promotes the growth rate of the seaweed after attachment. This is presumed to be due to the cotton-like bamboo fibers contained in the base layer and surface layer formed by spraying on the surface of the substrate concrete plate, which promote the enrichment of nutrients necessary for seaweed growth by inducing microorganisms, and the effect of the cotton-like bamboo fibers, which are planted with the fibers exposed on the surface layer by spraying, which increases the capture rate of seaweed spores floating in the water.

[0085] (7) Results of the test on the effect of inducing aquatic microorganisms in the base layer and promoting seaweed bed formation. In this invention, a base layer spray material is used as the "base layer" formed on the surface of the substrate, which is a bamboo fiber binder containing magnesium oxide, cotton-like bamboo fibers, and granular anhydrous magnesium chloride, mixed with water or seawater. Because this "base layer" contains cotton-like bamboo fibers, it has the effect of inducing microorganisms in the water and fixing fertilizer components necessary for the growth of aquatic plants within the base layer. Here, we will describe the results of a verification test of the effect of inducing aquatic microorganisms in the "base layer". Note that this test is a test of the effect of inducing microorganisms / promoting seaweed bed formation on the "base layer", and the formation of the "surface layer" in this invention (a surface layer formed by spraying a surface layer spray material containing cotton-like bamboo fibers (and / or granular sodium chloride) onto the upper layer of the base layer) was not performed.

[0086] (6.1) Test Method [1] First, two X-shaped concrete blocks (referred to as "X blocks") used for seawalls are prepared as the substrate.

[0087] [2] Each X block is divided by a central axis of symmetry. One side is designated as a test section where a base layer is formed by spraying a base layer spray material containing a bamboo fiber binder with magnesium oxide, cotton-like bamboo fibers, and granular anhydrous magnesium chloride mixed with water, while the other side is designated as a control section where nothing is sprayed and the surface of the substrate concrete is exposed.

[0088] [3] The two X blocks were sunk to the seabed at a depth of approximately 3m, and after 6 months, the surface of the test and control sections of each X block was peeled off from the seawater in which they were sunk, and the seawater was collected along with the samples. The amount of chlorophyll a (the main photosynthetic pigment found in photosynthetic organisms such as plants, algae, and cyanobacteria) and pheophytin (a substance produced when magnesium ions are removed from chlorophyll molecules and replaced with two hydrogen atoms; it is produced from chlorophyll when plants and algae die, and is one of the substances that cause green chlorophyll to fade and turn into a brown substance) contained in the collected samples was measured.

[0089] [4] Furthermore, 15 months after being submerged on the seabed, surface photographs were taken of the test and control plots, and the seaweed cover (the percentage of the surface area covered by seaweed) was measured.

[0090] (6.2) Test results Figure 12 shows a photograph of the X block (hereinafter referred to as "test block") immediately after spraying, in which the above-mentioned test and control plots were formed. Figure 13 shows a photograph of the test block six months after it was sunk to the seabed. The experiment was conducted in Kashiwabara Fishing Port, Ashiya Town, Fukuoka Prefecture. From the photographs taken six months later, it can be observed that the growth of established seaweed was faster in the test plot compared to the control plot.

[0091] Table 4 shows the results of measuring the amounts of chlorophyll a and pheophytin on the surface of the test and control sections of the two test blocks after 6 months.

[0092] [Table 4]

[0093] Table 4 shows that the average amounts of chlorophyll a and pheophytin measured on the surfaces of the test and control sections in the two test blocks were higher in the test sections compared to the control section. This result indicates that more photosynthetic microorganisms (prokaryotes (bacteria) that synthesize organic matter using light energy) in the water were induced on the basal surface of the test sections compared to the control section.

[0094] Figure 14 is a photograph showing the external appearance of the test block 1 year and 7 months after it was sunk to the seabed. From Figure 14, it can be seen at a glance that the test area is covered with seaweed over a larger area compared to the control area.

[0095] Table 5 shows the results of measuring seaweed cover on the surfaces of the test and control sections of the two test blocks after 1 year and 7 months. The locations of the "top surface" and "slope" of the "block section" in Table 5 are shown in Figure 12(b).

[0096] [Table 5]

[0097] Table 5 shows that the average seaweed cover of Ulva and red algae measured on the surface of the test and control sections in the two test blocks was higher in the test sections compared to the control section in both cases. This result indicates that forming a basal layer on the substrate surface promotes seaweed bed formation more effectively than a bare substrate surface. [Explanation of symbols]

[0098] 1. Spraying device 2. Base layer spray material storage section 3. Surface spray material storage section 4 Water Tanks 5. Mucus Tank 6. Air compressor 7. Spray material feeding device 7a Input hopper 7b Air intake port 7c Discharge port 7d Inlet tube 7e Mixing channel 7f stirring shaft 7g stirring blade 7h drive motor 7i Belt Transmission Mechanism 8. Means for switching the spray material input 9. Spray nozzle 10. Spray hose 11 Water supply pump 12 Water supply hose 12a Water supply hose connection 14 Water tap 15. Mucus pump 16 Mucus Hose 16a Mucus hose connection 18 Mucus Cock 19 Branch pipe

Claims

1. A method for manufacturing a structure for installation in a body of water to promote the formation of seaweed beds underwater, A base layer formation step involves forming a base layer by spraying a base layer spray material, which is a mixture of magnesium oxide, cotton-like bamboo fibers obtained by crushing and pulverizing raw bamboo rods so that the cell walls of the fiber cells are split, and a bamboo fiber binder containing granular anhydrous magnesium chloride, with water or seawater, onto the surface of a substrate submerged in water. Before the base layer formed in the base layer formation step solidifies, A surface layer formation step involves spraying the surface layer spray material containing the cotton-like bamboo fibers onto the surface of the base layer to form a surface layer in which the surface layer spray material penetrates into the surface region inside the base layer, A method for manufacturing a structure for installation in a body of water, characterized by having the following features.

2. In the aforementioned surface layer formation step, Before the base layer formed in the base layer formation step solidifies, The surface of the base layer is sprayed with a surface layer spray material containing the cotton-like bamboo fibers and granular sodium chloride, thereby forming a surface layer in which the surface layer spray material penetrates into the surface area inside the base layer. A method for manufacturing a water body structure according to claim 1, characterized by the above.

3. In the aforementioned base layer formation process, The aforementioned bamboo fiber binder is air-transported to the spray nozzle by the airflow discharged from the air compressor, Water or seawater, pressurized by a water pump, is injected into the airflow containing the bamboo fiber binder at the base end of the spray nozzle, and the bamboo fiber binder and water or seawater are mixed inside the spray nozzle and sprayed onto the surface of the structure to be installed in the water area. In the initial surface layer formation process, The aforementioned surface spray material is air-transported to the spray nozzle by the airflow discharged from the air compressor and sprayed onto the surface of the structure to be installed in the water. A method for manufacturing a water body structure according to claim 1, characterized by the above.

4. Before the aforementioned base layer formation step, A mucus coating process in which an aqueous magnesium chloride solution is sprayed onto the surface of the substrate, thereby coating the surface of the substrate with the aqueous magnesium chloride solution. A method for manufacturing a water body structure according to claim 1, characterized by comprising the above.

5. The base layer spray material housing section that houses the bamboo fiber binder, A surface spray material housing section for housing the aforementioned surface spray material, A water tank that contains water or seawater, An air compressor that discharges an airflow for pneumatically transporting the spray material, A spray material feeding device that feeds the spray material into the airflow discharged from the aforementioned air compressor, The spray material input device provides a means for switching between the bamboo fiber binder contained in the base layer spray material containment section and the surface layer spray material contained in the surface layer spray material containment section, and the spray material to be introduced into the airflow by the spray material input device. A spray nozzle that ejects the spray material, A spray hose connected to the airflow outlet of the spray material feeding device and the spray nozzle, A water pump for pumping water or seawater from the water tank, A water supply hose connected to the base end of the spray nozzle or to the spray hose and the discharge port of the water supply pump, A water cock is provided at the base end of the spray nozzle or at the water supply hose connection point, which is the connection point between the spray hose and the water supply hose, and is used to switch the flow of water or seawater injected from the water supply hose to the base end of the spray nozzle or the spray hose, Using a spraying device equipped with the following features, In the base layer formation step and the surface layer formation step, the spray material to be introduced into the airflow by the spray material input device is switched by the spray material input device using the spray material switching means of the spraying device to either the bamboo fiber binder contained in the base layer spray material containment section or the surface layer spray material contained in the surface layer spray material containment section, thereby performing the spraying work on the surface of the substrate using the same spray nozzle. In the base layer formation step, the water cock is opened and the base layer spraying work is carried out while mixing the bamboo fiber binder with water or seawater in the section from the water supply hose connection to the discharge port of the spraying nozzle. In the surface layer formation step, the water cock is closed and the spraying of the surface layer material is carried out. A method for manufacturing a water body structure according to claim 1, characterized by the above.

6. The aforementioned spraying device is A mucus tank containing a magnesium chloride aqueous solution, A mucus pump for pumping the magnesium chloride aqueous solution in the mucus tank, A mucus hose connected to the base end of the spray nozzle or to the spray hose and the discharge port of the mucus pump, A mucus cock is provided at the base end of the spray nozzle or at the mucus hose connection point, which is the connection point between the spray hose and the mucus hose, and is used to switch the flow of magnesium chloride aqueous solution injected from the mucus hose to the base end of the spray nozzle or the spray hose, It is equipped with, Before the aforementioned base layer formation step, The process includes a viscous coating step in which an aqueous magnesium chloride solution is applied to the surface of the substrate by spraying it onto the substrate surface. In the aforementioned mucus application process, the spray material input device is stopped, and while an airflow is discharged from the air compressor, the mucus cock is opened, and the magnesium chloride aqueous solution, which is pumped from the mucus tank by the mucus pump, is sprayed onto the base layer spray material using the spray nozzle. A method for manufacturing a water body structure according to claim 4, characterized by the above.

7. The aforementioned surface spray material is further enriched with a granular porous glassy algae growth material that releases divalent iron ions into the water when immersed in water. A method for manufacturing a water body structure according to claim 1, characterized by the above.

8. In the base layer formation step, the bamboo fiber binder is sprayed onto the surface of a substrate submerged in water as a base layer spraying material, which is a mixture of water or seawater and citric acid. A method for manufacturing a water body structure according to claim 1, characterized by the above.

9. The base layer spray material housing section that houses the bamboo fiber binder, A surface spray material housing section for housing the aforementioned surface spray material, A water tank that contains water or seawater, An air compressor that discharges an airflow for pneumatically transporting the spray material, A spray material feeding device that feeds the spray material into the airflow discharged from the aforementioned air compressor, The spray material input device provides a means for switching between the bamboo fiber binder contained in the base layer spray material containment section and the surface layer spray material contained in the surface layer spray material containment section, and the spray material to be introduced into the airflow by the spray material input device. A spray nozzle that ejects the spray material, A spray hose connected to the spray nozzle and the airflow outlet of the spray material feeding device, A water pump for pumping water or seawater from the water tank, A water supply hose connected to the base end of the spray nozzle or to the spray hose and the discharge port of the water supply pump, A water cock is provided at the base end of the spray nozzle or at the water supply hose connection point, which is the connection point between the spray hose and the water supply hose, and is used to switch the flow of water or seawater injected from the water supply hose to the base end of the spray nozzle or the spray hose, A spraying device characterized by being equipped with the following features.

10. The aforementioned spraying device is A mucus tank containing a magnesium chloride aqueous solution, A mucus pump for pumping the magnesium chloride aqueous solution in the mucus tank, A mucus hose connected to the base end of the spray nozzle or to the spray hose and the discharge port of the mucus pump, A mucus cock is provided at the base end of the spray nozzle or at the mucus hose connection point, which is the connection point between the spray hose and the mucus hose, and is used to switch the flow of magnesium chloride aqueous solution injected from the mucus hose to the base end of the spray nozzle or the spray hose, The spraying apparatus according to claim 9, characterized by comprising the following features.

11. A structure for installation in a body of water that is submerged on the seabed to promote the formation of seaweed beds underwater, A base layer is formed by mixing a bamboo fiber binder containing magnesium oxide, cotton-like bamboo fibers obtained by crushing and grinding raw bamboo rods so that the cell walls of the fiber cells cleave, and granular anhydrous magnesium chloride with water or seawater and hardening it, which is formed on the surface of the substrate. The base layer comprises a surface layer formed on the surface of the base layer, in which the cotton-like bamboo fibers are embedded and fixed to the surface layer region inside the base layer. A structure for installation in a body of water, characterized in that a portion of the cotton-like bamboo fibers of the surface layer are exposed on the surface of the surface layer.

12. The water body structure according to claim 11, characterized in that granular sodium chloride is scattered in the surface layer, and a portion of the surface of the granular sodium chloride is exposed on the surface of the surface layer.

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