JP2552985B2 - Sea surface reclamation material and its manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sea landfill material comprising a cementitious mixture whose main component is waste such as fly ash recovered from a thermal power plant, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, harmful components and flue ash in flue gas generated in a thermal power plant are recovered, and a suspension containing lime or limestone is mixed therewith to form a cementitious mixture.
It has been proposed to use this as a building material such as a building filler, a brick, or a road base material (Japanese Patent Publication No.
-10057). Further, conventionally, sand and earth and sand have been used as landfill materials.

[0003]

The cementitious mixture obtained by the above proposal is alkaline, has no elution of harmful substances, and has the property of being powdery and solidifying by a chemical reaction, and having the property of being hard to permeate due to solidification. When this mixture is used as a base material for roads, for example, the mixture sprinkled by a heavy machine is compacted to form a hardly water-permeable roadbed. This cementitious mixture is industrial waste, and if it can be used for as many purposes as possible, it is preferable because the waste is recycled and the effective utilization of resources is increased, but at present, it is only used in a granular state as a construction material. Not not. Moreover, when left in the atmosphere, the solidification reaction naturally proceeds and solidifies. Therefore, the cementitious mixture must be used within about two weeks after its production, which is inconvenient with a time limitation. It was On the other hand, when sand and earth are used for the landfill material as in the past, loose ground is created because it cannot be compacted in the sea, and it becomes a ground that is easily fluidized and liquefied during an earthquake. As a countermeasure, it is also possible to mix a binder such as cement with sand or the like in advance to make a sea surface reclamation material, but this is troublesome to process and the material cost is expensive. If the solidifying property of the cementitious mixture is exerted even in the sea, it is convenient because the use as a landfill material can be expanded and the effective use of waste can be expanded. It is an object of the present invention to provide an easy-to-handle sea surface landfill material produced from the above cementitious mixture, and to propose a method for producing the same.

[0004]

In the present invention, the aqueous suspension contains 30 to 90% by weight of solids, and the solids are 0.2%.
5 to 70% by weight of alkaline earth metal hydroxide and 1
0 to 99.5% by weight fly ash and 0.25
To 70% by weight of an alkaline earth metal sulfite (a part of this sulfite is an alkaline earth metal sulfate), a cementitious mixture is once solidified, then crushed, and dried to facilitate handling. A sea surface reclamation material that can form a strong ground was obtained. This sea surface reclamation material is obtained by solidifying the cementitious mixture while compacting it, crushing the solidified product into a state in which coarse particles and fine particles are mixed, and then drying to prevent a solidification reaction in the atmosphere. It is manufactured by carrying out.

[0005]

The above cementitious mixture produced by the production plant is a granular material having alkalinity, and the solidification reaction of the pozzolanic reaction or the salfopozolan reaction proceeds while compacting this, and for example, the uniaxial compressive strength becomes about 10 kg / cm ² . Let it solidify. This solidified material is crushed by a machine such as a twin header so as to have a particle size distribution in which coarse particles and fine particles are appropriately mixed, and even when dumped in the sea, fine particles are mixed in between the coarse particles. Crush the crushed materials so that they can bite each other. Then, the crushed material is naturally dried or forcedly dried to stop the progress of the solidification reaction. This crushed material can withstand long-term storage because it is dry, and when it is dumped into the sea, the solidification reaction starts again, and because the crushed materials are in good mesh with each other, they solidify in a connected state and have strong ground. Can be created in the sea.

[0006]

EXAMPLE The exhaust gas of a thermal power plant is introduced into a limestone slurry to obtain a slurry containing calcium sulfite and calcium sulfate, and fly ash discharged together with the boiler exhaust gas is added thereto, and then the water content thereof is adjusted. The cementitious mixture is obtained by mixing lime. An example of the composition is as follows. Water 20% CaSO ₃ 1 / 2H ₂ O + CaSO ₄ 2H ₂ O 25% Unreacted limestone (CaCO ₃ ) 12% Fly ash 40% Slaked lime (Ca (OH) ₂ ) 3% This cementitious mixture is finely granular. However, when it is left to stand in the atmosphere, it has a property of solidifying in about 2 weeks due to solidification reaction of pozzolanic reaction and salfopozolan reaction, and conventionally, it was necessary to use it promptly after its production. This cementitious mixture has a density (wet density) of 1.
6 to 1.78 g / cm ³ , for example, when used by rolling as roadbed material, the uniaxial compressive strength becomes 27 to 6 after the lapse of days.
It becomes 7 kg / cm ² . In the case of the present invention, the cementitious mixture produced is treated with water, for example with a dry weight ratio of 23%.
Compacted while adjusting to ~ 26% and aged at 20 ° C for 1 to 2 weeks to solidify, and crush when the solidified product does not completely solidify and the uniaxial compressive strength reaches the range of 9 to 11 kg / cm ^2. To do. For crushing, the particle size is 150 to 150
It is preferably distributed in a range of ˜1 mm. For that purpose, it is preferable to perform it in a twin header in which rock is cut by a rotating bit for finishing a cutting surface in excavation of a mine or a tunnel. If the crushed material is left as it is, the crushed materials will reconnect with each other due to the solidification reaction over time, but immediately after crushing, it will be solidified if the density is adjusted to 1.3 to 1.4 g / cm ³ by natural drying or forced drying. It becomes a sea surface reclamation material in a state where the reaction does not proceed, and can be stored for a long period of time in the separated crushed state. When this dry landfill material of various particle sizes is naturally dumped into the sea for landfill, fine particles are deposited between coarse particles and coarse particles, and between the crushed materials by seawater. Are connected by a solidification reaction, and it is possible to construct a ground of ² to 5 kg / cm ² with uniaxial compressive strength in the sea that cannot be compacted. If the landfilled ground has this level of strength, it is resistant to disasters such as earthquakes, easy to excavate and pile, and is suitable for subsequent land use.

A specific embodiment of the present invention will be described below. As a cementitious mixture, the dry weight ratio of fly ash of a thermal power plant to 100 is CaSO ₃ 1 / 2H ₂ O.
A mixture of + CaSO ₄ .2H ₂ O, unreacted limestone (CaCO ₃ ) and slaked lime in a total weight of 4 to 20 was used as a raw material.
This cementitious mixture has a specific gravity of about 2.3 and a wet density of 1.7 kg / cm ³ , and it is compacted by adding 25% of its dry weight of water and aged for 10 days to complete the solidification reaction. Thus, a solidified product having a uniaxial compressive strength of 10 kg / cm ² was obtained. This solidified material is crushed with a twin header, and the particle size is up to 150m.
The distribution was from m to a minimum of 1 mm. The particle size distribution of the crushed material crushed by the twin header is shown in the following table.

[0008]

[Table 1] The crushed material has a wet density of 1.7 kg / cm ^3, but which was adjusted density dried 1.3~1.4kg / cm ³ and sea landfill material. When dried to this density, the cementitious mixture did not undergo a solidification reaction and could be stored in a gravel state for a long period of 6 months or longer in a sealed state. When the sea surface reclamation material stored for 6 months was naturally dumped into the sea for reclamation, a ground having a uniaxial compressive strength of 2 to 5 kg / cm ² could be formed on the seabed after 28 days. This is because the dry landfill material started the solidification reaction of pozzolan and salphopozolan again due to the infiltration of seawater, and a ground that can be excavated and piled strongly against a relatively strong earthquake without compaction was obtained. Was given.

If the uniaxial compressive strength of the cementitious mixture is too small, it decomposes into fine particles when landfilling at sea (slaking).
It is inconvenient, and if the strength is too large, it is difficult to crush, and it is preferable that the strength is about 9 to 11 kg / cm ² . Further, the cementitious mixture has a density of 1.2 to 1.3 g / cm ³ when it is most dried, but it takes time and cost to dry it until now, and the density is 1.3 to 3
It was found that the solidification reaction could be sufficiently suppressed by adjusting the amount to 1.4 g / cm ³ .

[0010]

As described above, according to the present invention, the aqueous suspension contains 30 to 90% by weight of a solid matter, and the solid matter is less than 0.1%.
25 to 70% by weight of alkaline earth metal hydroxide,
10 to 99.5% by weight fly ash and 0.2
A cementitious mixture consisting of 5 to 70% by weight of an alkaline earth metal sulfite (a part of this sulfite is an alkaline earth metal sulfate) is once solidified, and then coarse and fine particles are mixed. Since it is crushed to a state that allows it to be further dried and used as sea surface reclamation material, it can be stored for a long time and is convenient to use. The ground can be naturally created, the manufacturing method thereof is relatively simple and inexpensive, and the effective use of the cementitious mixture, which is an industrial waste, is expanded.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location E02B 3/18 B09B 3/00 301S

Claims (3)

(57) [Claims] 1. An aqueous suspension containing 30 to 90% by weight of solids, wherein the solids are 0.25 to 70% by weight of alkaline earth metal hydroxide and 10 to 99.5% by weight. fly ash and 0.25 (part of the sulfite is an alkaline earth <br/> gold Shoku硫 salt) 70 wt% of an alkaline earth metal sulfite cementitious mixture consisting was once solidified A sea surface reclamation material characterized by being crushed and then dried. 2. Aqueous suspension containing 30 to 90% by weight of solids, said solids being 0.25 to 70% by weight of alkaline earth metal hydroxide and 10 to 99.5% by weight. the fly ash and cementitious mixture comprising 0.25 to 70 wt% of an alkaline earth metal sulfites (part of the sulphite salt is an alkaline earth <br/> gold Shoku硫 acid salt), while compacted A method for producing a sea landfill material, which comprises solidifying, crushing the solidified product into a state in which coarse and fine particles are mixed, and then drying to prevent a solidifying reaction in the atmosphere. 3. The uniaxial compressive strength of 9 to 1 by allowing the solidification reaction to proceed halfway while compacting the cementitious mixture.
Solidified to 1 kg / cm ² and the solidified product 150 mm to 1 m
The method for producing a sea surface landfill material according to claim 2, wherein the crushed material is a crushed material in which particles having a particle diameter of m are mixed and dried to such an extent that the solidification reaction of the cementitious mixture does not proceed.