JPH078137A - Artificial alga reef - Google Patents

Abstract

PURPOSE:To prevent elution of an alkali from an artificial alga reef made of concrete and simultaneously, provide conditions suitable for rearing algae. CONSTITUTION:Slurry obtained by adding water to calcined gypsum is applied to the surface of a concrete structure containing the hollow interior.

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 a concrete artificial reef and a concrete structure 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"). In particular, the present invention relates to an artificial algal reef in which the surface is covered with gypsum to suppress the elution of alkaline components in concrete into water so that aquatic organisms can easily grow.

[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 structures such as newly constructed concrete artificial fish reefs installed in water and revetments for river / shore revetments and blocks for wave-dissipation have a high alkalinity on the surface of the concrete. Compared with river water, aquatic organisms are not able to settle in, so to speak the state 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 addition, Japanese Examined Japanese Patent Publication No. 63-4
No. 1527 uses a penetrant consisting of a water-soluble resin and a surfactant, in addition to the method of Japanese Patent Publication No. 59-41527. Further, in JP-A-61-289825, p
Cement of by-product ferrite, which is said to be H close to seawater,
A slurry is applied to the surface of a concrete structure as a slurry with a binder such as asphalt or a resin, or a solidified product is combined to form a structure, or an artificial reef is attached to the surface of a concrete structure.

[0004]

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.

In the proposal of artificial reef using by-product ferrite and a binder, by-product ferrite is (a) resistance to external force, (b) high strength, (c) early strength development, and (d). It is said to have advantages such as affinity with seawater and (e) confirmation by magnetic force at the place of sedimentation. The effect of preventing alkali elution from concrete seems to be due to (a), (b) and (c). Be done. Then, when the synthetic resin is used as a binder, the concrete surface is coated with the synthetic resin coating film,
Although the elution of alkaline components can be suppressed more effectively, the added inorganic fine powder, the by-product ferrite, is almost buried in the synthetic resin coating film, and the effect (d), (e)
Does not appear. Moreover, when a polymerization-curable synthetic resin is used, the cured resin cannot be reused.

[0006]

In order to achieve the above object, the present invention has focused on the use of gypsum as a shoe on the surface of a concrete structure. Here, the gypsum applied to the surface of the artificial reef has a pH of about 5 and is slightly acidic, and suppresses the elution of the alkaline component in the concrete structure from the surface to water, and the coating film against the living body. It has been found that it has good compatibility, has a function of assisting the growth of aquatic organisms such as algae and cultivating them, and is very suitable as a coating for artificial reefs.

Therefore, a first aspect of the present invention relates to an artificial reef characterized by applying a slurry of calcined gypsum to which water has been applied to the surface of a concrete structure including the inside of a cavity, and also the first aspect of the present invention. The second relates to an artificial reef characterized by applying a slurry prepared by adding water to a mixture of calcined gypsum and silica sand to the surface of a concrete structure including the inside of a cavity.

The gypsum used in the present invention is (a) non-toxic, (b) it covers the surface of concrete and suppresses the elution of alkali, and (c) calcium has an algae-growing effect, (d) Since it has properties such as being poorly soluble in water, it is used as a coating for concrete structures.
As calcined gypsum, calcined gypsum phosphate, salt gypsum, etc. can be preferably used. Furthermore, by including silica sand in the gypsum in advance, the hardness of the surface of the gypsum layer can be increased to improve the wear resistance and the surface can be roughened to form a foothold on which aquatic organisms grow.
The silica sand preferably has a particle size of 0.1 to 3 mm and is used in an amount of 10 to 50% by weight. Starting material consisting of gypsum or gypsum and silica sand is used in an amount of 10-50 with respect to 100 parts by weight of water.
Mix in 1 part by weight, apply to the surface of concrete, and then dry naturally to form a coating layer. This coating layer is preferably formed to have a thickness of 1 to 5 mm. Hereinafter, the present invention will be described with reference to examples.

[0009]

【Example】

Example 1 Example 1 of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows thickness: 120 mm, height 190 mm, length 39.
Figure 3 shows a hollow concrete block with dimensions of 0 mm. FIG. 2 shows the hollow concrete blocks of FIG. 1 stacked in multiple stages such that the hollow portions of the blocks are horizontal. The hollow concrete blocks 1 having the hollow portion 1 are shown only in the upper two rows. . Moreover, the upper part is opened so that the structure is exposed to more sunlight. Gypsum slurry (water: 100 parts by weight, gypsum: 150 parts by weight) in which silica sand with an average particle size of 0.2 mm was added to the gypsum in an amount of 50 wt% was applied beforehand to an average thickness of 1 mm and naturally dried. A large number of the concrete blocks were stacked in a structure having a through cavity and installed in the sea to make an artificial algae reef, which was installed in the sea and tested. 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.

Example 2 (Comparative Experiment) An artificial algal reef was produced under the same conditions as in Example 1 except that no coating film was applied, and the test was carried out by setting it in seawater. By the time, no algae had settled.

[0011]

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 be used for algae and other aquatic organisms. It was confirmed that the plant flourished and that the fish reef was sufficiently effective. Therefore, the present invention solves one of the current 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.

[Explanation of symbols]

 1 Hollow concrete block 2 Opening 3 Bottom plate

Claims (2)

[Claims] 1. An artificial reef characterized by applying a slurry of calcined gypsum to which water has been applied to the surface of a concrete structure including the inside of a cavity. 2. An artificial reef characterized by applying a slurry prepared by adding water to a mixture of calcined gypsum and silica sand to the surface of a concrete structure including the inside of a cavity.