JP2006025629A - Concrete block for seaweed bed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems of conventional concrete blocks for seaweed beds, wherein the conventional concrete blocks are generally produced from Portland cement and thereby give pH 12 to 13 on their peripheries which are too high (namely, the alkaline property is too strong) for animals and plants, while the pHs of general seas are about 8.2 to 8.4, and further wherein the iron contents of ordinary cements are small, for example, a ferric oxide content of 2 to 5% in a case of Portland cement, while the iron content is generally essential for algae which fast grow in a high iron content. <P>SOLUTION: This concrete block for the seaweed bed is characterized by comprising porous concrete prepared by curing a mixture comprising at least steel making slag and blast furnace slag fine powder with water to give a porosity of 10 to 30%, wherein the porous concrete is molded in various shapes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a block for algae beds.

  The seaweed block is a block for algae to take root and grow there. Such seaweed beds are conventionally made of various materials, but are often made of concrete blocks because they are easy to mold and inexpensive. However, a simple concrete block has a low level of grounding because it has weak adhesion to algae roots and is exposed to tides and waves.

Therefore, so-called porous concrete having many voids has been used. This is to fix a porous concrete plate to a part of the entire block as described in Patent Document 1.
JP 2000-350533 A

  Such porous concrete certainly has excellent root fixation in terms of physical shape, and the flooring rate is greatly improved.

  However, since ordinary Portland cement is used, various components are eluted in water, and the components and pH of water around the block change. For example, in Portland cement, the surrounding pH rises to 12-13. Of course, since the sea is wide, it will be thin if there is a distance, but it will be 10 or more around the block.

Since the normal sea pH is about 8.2 to 8.4, the pH is too high for animals and plants. That is, the alkalinity is too strong.
Moreover, normal cement has little iron content, and in the case of Portland cement, it is 2 to 5% with ferric oxide. Generally, iron is essential for the growth of algae.

  In view of the situation as described above, the present inventor has completed the algae block for the present invention as a result of diligent research. The feature of the present inventor is that a mixture containing at least steelmaking slag and blast furnace slag fine powder is included in the porosity. It is porous concrete hardened with water so that it may become 10-30%, and is in the point molded into various shapes.

  The point of the present invention is that the main body is made porous and steelmaking slag is used. Recalling the combination of the two, the present invention has been completed.

  Steelmaking slag is slag produced in the steelmaking process of steel production, and includes calcium oxide, silicon oxide, iron oxide, magnesium oxide, aluminum oxide, manganese oxide and the like. This is a relatively large one and also serves as an aggregate. The size is not particularly limited, but a mixture of large to small is preferable. Usually, it is a mixture of several mm to 20 mm.

The reason for using this steelmaking slag is as follows.
First of all, when they are put in water, the pH is 8.3 to 8.4, which is almost the same as normal seawater. Thereby, there is no influence on marine organisms by pH. Moreover, since iron is 2 to 3% in ordinary cement, steelmaking slag is very much (many things are 20% or more), so it is good for the growth of marine plants.
Conversely, the normal calcium content is 60% or more, which is too much, but it is small in steelmaking slag. Other magnesium and aluminum contents are also suitable for animals and plants compared to Portland cement.

Blast furnace slag fine powder is obtained by rapidly cooling and finely pulverizing slag produced in the iron making process of steel production with water.
This is a hydraulic reaction that solidifies the whole.

  The two components and water are mixed and solidified into a block shape. At this time, the point is to set the porosity to 10 to 30%. This was experimentally found from the balance between the overall strength and the agglutination strength of algae.

  The mixing ratio of the steelmaking slag, blast furnace slag fine powder, and water is not particularly limited. However, with respect to 100 parts by weight of the steelmaking slag, 10-50 parts by weight of the blast furnace slag fine powder and about 10-50 parts by weight of water Is preferred.

  Furthermore, blast furnace granulated slag (slag produced by quenching and pulverizing slag generated during steelmaking process with water), fly ash (pulverized ash generated by pulverized coal combustion boiler), slaked lime, etc. An alkali stimulant may be added.

  The shape of the block is not limited, but it may be a block shape that is a rectangular block, a desk block shape with legs, a frame shape with a gap in the inside, or any other shape. The size is also free, and can be from about 10 cm to several meters or more.

  The block of the present invention can be simply submerged in the sea. Nature and seaweeds adhere to it and become a seaweed bed. In addition, fish also gather in the algae or blocks themselves and become fishing reefs. Furthermore, it is good also as a farm for seaweed and shellfish.

The block for the seaweed bed of the present invention has the following effects.
(1) Since the present invention block uses steelmaking slag instead of ordinary Portland cement as its raw material, it does not elute those that adversely affect animals and plants.
(2) Since steelmaking slag is used, algae are likely to adhere biologically.
(3) Since the porosity is 10 to 30%, physical adhesion of algae is improved.
(4) Since the pH is close to seawater, the pH of the surrounding seawater is not changed.

  Hereinafter, based on an Example, this invention is demonstrated in detail.

Each block was manufactured with the mixing ratio shown in Table 1. Here, the numerical value is the weight (Kg) with respect to the completed block 1 m3. The slag dimension is a size that includes 90% of the slag. The fine powder is blast furnace slag fine powder. Moreover, what was mixed with a normal concrete block was mixed with these. For example, a water reducing agent.

The manufactured block 1 is a desk block type as shown in FIG. 1 and has a size of about 50 × 50 × 30 cm.
Further, as an example, a block having the same shape was produced by using a normal Portland cement as Comparative Example 1.

Table 2 shows the results of submerging each block in the sea of Mizushima Port, Okayama Prefecture.
The attached biomass in Table 2 is obtained by quantifying the amount attached to the block of Comparative Example 1 after 10 months as 100 parts by weight and relative evaluation thereof. As far as this is seen, the amount of marine plants fixed is very large and increases with time. However, in Comparative Example 1, it does not exceed a certain level. This is considered to be due to falling (desorption due to the flow of water).

  Also, the number of attached organisms is larger than that in Comparative Example 1. This also seems to be accepted by many types of plants and fixed animals.

It is a perspective view which shows one example of the block for this invention seaweed beds.

Claims (3)

A block for seaweed beds, which is porous concrete obtained by hardening a mixture containing at least steelmaking slag and fine powder of blast furnace slag with water so as to have a porosity of 10 to 30%, and is molded into various shapes. Furthermore, the block for seaweed beds of Claim 1 which mixes at least 1 sort (s) among blast furnace granulated slag, fly ash, or slaked lime. The block for seaweed beds according to claim 1 or 2, which is of a desk block type.

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