JPH0723675A - Artificial algal reef and its production - Google Patents

Abstract

PURPOSE:To prevent dissolution of alkali components from an artificial algal reef and promote adhesion of organisms. CONSTITUTION:A coating film composed of calcium phosphate or a calcium phosphate coating film to which staples are fixed is formed on the surface of a concrete structured whose inside is hollow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial algal reef. More specifically, it is applied to the surface of concrete artificial fish reefs and concrete structures for seawall protection such as river / coast embankments and wave-dissipating blocks. The present invention relates to an artificial reef that allows algae to grow (hereinafter referred to as "artificial algae") and a method for manufacturing the artificial reef. In particular, the present invention covers the surface with calcium phosphate, suppresses the elution of alkaline components in concrete into water, and makes the surface state in which aquatic organisms easily grow, and more preferably fine short fibers in the calcium phosphate film. The present invention relates to an artificial algal reef, which is used as a stepping stone for aquatic organisms to be attached.

[0002]

2. Description of the Related Art Generally, the pH of the surface of a concrete structure at the time of its production is as high as 11 to 13, but the pH of ordinary river water is 6 to 7, and the pH of seawater is 7.7 to 8. ．
Since it is 4, living things that live in water are in a situation where they cannot settle on the surface of this concrete structure. Conventionally, concrete artificial reefs that are newly manufactured and installed in water, and concrete structures such as embankments for river and coast revetments and blocks for wave breaking are aquatic organisms due to the high alkalinity of the concrete surface. Can not settle, so to speak, it is in the condition of a concrete desert. Although concrete removal is sometimes done, this is not a very fundamental solution, so the so-called shore burning phenomenon occurs nationwide in coastal areas, which is becoming a serious problem for coastal fisheries.

As a method for solving this problem, various proposals have been made so far. For example, Japanese Patent Publication Sho-59-415
In No. 27, by embedding ferrous sulfate or ferric sulfate crystals in the surface of a concrete structure to be an artificial reef and forming an infiltrated layer on the surface, the alkali component of the concrete is neutralized and It aims to supply iron as a nutrient.

In Japanese Patent Publication No. 63-41527, in addition to the method of Japanese Patent Publication No. 59-41527, a penetrant consisting of a water-soluble resin and a surfactant is used. Also,
In JP-A-61-289825, by-product ferrite, which is said to have a pH close to that of seawater, is applied to the surface of a concrete structure as a slurry with a binder such as cement, asphalt, or a resin, or is combined into a plate. As a structure or as an artificial reef attached to the surface of a concrete structure.

[0005]

However, the Japanese Patent Publication No. 59-
According to the method proposed by No. 41527, when the structure is immersed in water and the crystals such as ferrous sulfate as the main ingredient are water-soluble, those agents easily dissolve and quickly diffuse into water. And the complicated processing steps for embedding crystals in concrete, resulting in an overall high cost. Furthermore, even if partially embedded ferrous sulfate, etc. dissolves in water at the embedded part, it reacts with the alkaline components contained in the surrounding concrete to form iron hydroxide, which forms a film on the concrete surface. Covering,
There is a possibility that ferrous sulfate or the like may be prevented from permeating and spreading over a wide area.

Further, in the proposal of an artificial reef using by-product ferrite and a binder in JP-A-61-28982, by-product ferrite is (a) resistance to external force, (b) high strength,
(C) It is said that it has advantages such as early strength development, (d) affinity with seawater, and (e) confirmation of sedimentation site by magnetic force, and the effect of preventing alkali elution from concrete is (a), It seems that it depends on (b) and (c). Then, when the synthetic resin is used as a binder, the concrete surface is covered with the synthetic resin coating, and as a result, the elution of the alkaline component can be more effectively suppressed. Is almost buried in the synthetic resin coating film and does not show its effects (d) and (e). Further, when a polymerization-curable synthetic resin is used, the resin cured in the mixing container cannot be reused in the mixing container.

[0007]

In order to achieve the above-mentioned object, the present invention is characterized in that a film consisting essentially of calcium phosphate is formed on the surface of a concrete structure including the inside of a cavity. Propose artificial reef that does. The calcium phosphate used in the present invention (a) forms a phosphate compound insoluble or hardly soluble in water on the surface of the concrete structure, and (b) suppresses elution of the alkaline component,
(C) Since the phosphorus and calcium contained in the phosphoric acid compound film act as nutrients and (d) have a property such as good compatibility with living organisms, it provides good conditions for promoting the settlement of aquatic organisms.

[0008] Divalent metal oxides such as calcium oxide react with phosphoric acid to form a phosphate, which hardens, so that such a reaction is dispersed on the surface of the concrete structure. By doing so, it is possible to form a strong and highly adherent phosphate coating on the surface of the concrete structure. In particular, calcium phosphate, which has been hardened by the reaction of phosphoric acid with calcium oxide in concrete, forms a uniform film with excellent adhesion to concrete. The film thickness is 0.1 to 1.5
It is preferably mm.

In the present invention, the above-mentioned calcium phosphate may be used as an essential component, and in addition, short fibers such as chemical fibers and fibers may be used as an additional component to form a film from them. By making these fibers short fibers, it is easy to apply them to the concrete surface, and as shown in FIG. 3, many fibers 10 project from the surface of the film 11 or adhere in a cross-linking manner to form a foothold for bioemergence. You can The length of the short fibers 10 is preferably 1 to 5 mm. In the figure, 12 is concrete and 13 is calcium phosphate. Although it is preferable for a large amount of short fibers to adhere to the surface in terms of bio-epitaxial growth, it becomes difficult to disperse and adhere the short fibers evenly to the film. Therefore, the short fibers 10a attached to the surface of the film 11 are m2. It is preferably 5 to 50 g per unit. Therefore, in the above film, the preferred short fibers are 0.5 to
It is 5% by weight.

In the coating film according to the present invention, calcium oxide powder, short fibers and the like are applied to a concrete surface together with an aqueous phosphoric acid solution, the concrete surface is dissolved by phosphoric acid, and the dissolved and reacted calcium phosphate entrains powder and short fibers. It can be formed by solidifying at.

A preferable method is a method in which a phosphoric acid aqueous solution is applied to the surface of concrete by spraying or the like because the film forming step is simple. CaO contained in Portland cement (content in cement 63.8 wt%, JI
S standard), Fe2O3 (2.9wt% in the same), MgO (1.6 in the same)
wt%), MnO 2 (0.13 wt%) and the like to form the respective phosphates. These phosphates suppress the elution of alkali from concrete and act as nutrients.

When short fibers are further applied, the short fibers are mixed with water to form a slurry, which is poured over the surface of the concrete and spread, or sprayed by a spray,
It is preferable to apply a phosphoric acid aqueous solution after drying.
Furthermore, if the coating is heated by an infrared lamp or the like after the phosphoric acid reaction, a strong coating can be formed by a dehydration reaction at 75 ° C. or higher.

The present invention can be applied because calcium phosphate has good adhesion to a concrete structure, and can be an artificial algal reef on which algae well grow. Hereinafter, the present invention will be described in more detail with reference to the drawings.

[0015]

【Example】

Example 1 Example 1 of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows a hollow concrete block with dimensions of thickness: 120 mm, height 190 mm, length 390 mm. FIG. 2 shows an artificial algal reef in which the concrete blocks having the cavities shown in FIG. 1 are stacked in a structure having a large number of through holes and installed in the sea. Note that the hollow portion of the concrete block is shown only in the upper two rows, and is omitted in the lower rows. Or, the upper part of the artificial reef is opened so that as much sunlight as possible is irradiated. A fiber with a length of several millimeters or less made into pulp with water is applied to the surface of the concrete structure with a spray gun, and a 85% phosphoric acid aqueous solution is sprayed onto the surface of the concrete structure to spray the fiber onto the concrete surface. A calcium phosphate film in a state of being transplanted was formed. It was installed in the sea in December and a part of it was withdrawn to the ground every month to examine the condition of algae growth. About 3 months after installation in the sea, algae grew on the surface of the concrete (excluding the part where the sludge was deposited) and grew sufficiently. It was confirmed that algae grow well inside the concrete cavity. In addition, it was confirmed that the bottom as well as the side surface grew well, and both the bottom and the cavity grew roots on the ceiling and grew downward. In addition, it was confirmed that fish live in the cavity.

Comparative Example An artificial algal reef was produced under the same conditions as in Example 1 except that no coating film was applied, and a test was carried out by installing it in the sea. Was not confirmed.

Industrial Applicability As described in detail above, the present invention does not require complicated steps in implementation and can manufacture an artificial algal reef at low cost using inexpensive materials, and can produce algae as well as aquatic organisms. It was confirmed that the plant flourished and that the fish reef was sufficiently effective. INDUSTRIAL APPLICABILITY The present invention solves one of the present problems of coastal fisheries and is useful for promotion of fisheries.

[Brief description of drawings]

FIG. 1 is a diagram showing a hollow concrete block used in an example of the present invention.

FIG. 2 is a diagram showing a structure of an artificial algal reef used in an example of the present invention.

FIG. 3 is a schematic cross-sectional view of a film in which short fibers are transplanted.

[Explanation of symbols] 1 hollow concrete block 2 opening 3 bottom plate 10 short fiber 11 film

Claims (8)

[Claims] 1. An artificial algal reef characterized in that a film made of calcium phosphate is formed substantially on the surface of a concrete structure including the inside of a cavity. 2. The artificial algal reef according to claim 1, wherein short fibers are fixed to the film. 3. The artificial reef according to claim 1, wherein the calcium phosphate is formed by reacting phosphoric acid with concrete. 4. The artificial algal reef according to claim 1, wherein the thickness of the film is in the range of 0.1 to 1.5 mm. 5. The artificial algal reef according to claim 4, wherein the proportion of the short fibers in the film is 0.5 to 5% by weight. 6. The artificial algal reef according to claim 5, wherein 5 to 50 g of the short fibers are attached to the concrete structure in a cross-linked form per m 2 of surface area of the concrete structure. 7. A method for producing an artificial algal reef, which comprises bringing an aqueous solution of phosphoric acid into contact with the surface of a concrete structure containing cavities. 8. The method for producing an artificial algal reef according to claim 7, wherein the surface of the concrete structure previously coated with the short fibers is brought into contact with the phosphoric acid aqueous solution.