JP2552984B2 - Subsea casting method of cementitious mixture containing fly ash - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of using a cementitious mixture composed mainly of waste such as fly ash recovered from a thermal power plant as a casting material for undersea construction.

[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).

[0003]

The cementitious mixture obtained by the above proposal is alkaline, does not elute harmful substances, has a property of being powdery and solidifying by a chemical reaction, and a property of solidifying to be impermeable. When this mixture is used as a base material for roads, for example, a water-impermeable roadbed is constructed by rolling the mixture spread by a heavy machine. This cementitious mixture is industrial waste,
If it can be used for as many purposes as possible, it is preferable because the waste is recycled to increase the effective utilization of resources, but at present, it is only used in a granular state as a construction material. If the solidifying property of the cementitious mixture is exerted even in the sea, the use as a construction material for offshore structures will be expanded, and the effective use of waste can be expanded.

An object of the present invention is to propose a method of casting the above cementitious mixture in the sea and using it as a construction material.

[0005]

In order to achieve the above-mentioned object, the present invention comprises an aqueous suspension containing 30 to 90% by weight of a solid content, wherein the solid content is 0.25 to 70% by weight. Earth metal hydroxide and 10 to 99.5% by weight fly ash and 0.25 to 70% by weight alkaline earth metal sulfite (part of this sulfite is alkaline earth metal sulfate) Seawater was mixed with the cementitious mixture consisting of to form a slurry, and the slurry was cast in the sea. Cement may be mixed in the slurry.

[0006]

The above cementitious mixture produced by the production plant is a granular material having alkalinity, and when it is mixed with seawater to adjust the flow value to an appropriate value, it becomes a slurry form that can be pumped, and is provided in the sea. When placed in a frame, it solidifies in seawater over the course of days and becomes a solid material that can withstand lateral pressure. Although the strength of the solid matter is lower than that when concrete is cast in the sea, it has a solid strength higher than that of earth and sand and is advantageous in that waste can be used at a lower cost than concrete.

[0007]

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. Is kneaded with seawater to form a slurry, and when placed in the sea, the slurry solidifies in seawater and becomes a solid material that has less strength than concrete but withstands lateral pressure, for example, for constructing a pier caisson. It can be used as a construction material for deadline construction.

A specific example of the method of the present invention will be described below. As cementitious mixture, CaSO ₃ · 1 with respect to dry weight ratio of 100 of the fly ash of thermal power stations
_{/ 2H 2 O + CaSO 4 ·} 2H 2 O, a material obtained by 4-20 mixed unreacted limestone (CaCO ₃₎ and slaked lime with a total weight was used as a raw material. This cementitious mixture had a specific gravity of about 2.3, seawater was added thereto, and the mixture was stirred and kneaded to obtain a slurry having a flow value of 200 mm. Two rows of steel sheet piles 1 and 2 for cutting off the caisson construction area as shown in FIGS.
Attempted to place 3 in the sea. The slurry solidified in the sea and gradually increased in strength to reach a strength of about 10 kgf / cm ² , becoming a solid material having a strength lower than that of concrete but higher than that of earth and sand. The area 4 surrounded by the inner steel sheet pile 2 is drained for construction of the caisson, but at this time, in order to prevent the steel sheet pile from falling inside due to the force of the surrounding sea water, the inner and outer steel sheet piles 1 Between the two, a solid material that can withstand lateral pressure must be filled, and using concrete as the filling material is expensive, and earth and sand cannot withstand lateral pressure. The amount of slaked lime based on 100 fly ash is 2
It was suitable to be ~ 7.5. Moreover, when the flow value of the slurry is adjusted to 250 mm or more, the strength in seawater is insufficient, and when the flow value is adjusted to 180 mm or less, the fluidity of the slurry in the sea is insufficient and the strength of the completed solid is partially reduced. It is not preferable because it causes variations. The solids produced by the slurry of the above component range in the sea for 28 days have a uniaxial compressive strength of about 6 to 12 kgf / cm ² , which is greater than earth and sand, and the thickness of the solids is to some extent. If so, it is possible to prevent the steel sheet pile from falling down due to seawater pressure. This strength is about 20% lower than when the slurry in the above component range is solidified in air.

Cement may be further mixed with the above raw material at a ratio of 3 to 8 with respect to the dry weight ratio of fly ash 100. In this case, the uniaxial compressive strength increases as the flow value decreases and the ratio of cement increases. , Its strength is 10-34
It became as large as kgf / cm ² . However, since cement is used, it is expensive as a construction material. In the construction example above,
If the distance between the steel sheet piles 1 and 2 is set to 8 m, the caisson construction work can be safely carried out at a position 10 m below the sea surface by closing the sea surface of about 55 m square.

[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 of 5 to 70% by weight of alkaline earth metal sulfite (a part of this sulfite is alkaline earth metal sulfate) was kneaded with seawater to form a slurry, which was then poured into the sea. This makes it possible to effectively use the cementitious mixture, which is industrial waste, as a material for undersea construction.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

2 is a cutaway side view of FIG.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location E02D 15/06 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. a cementitious mixture comprising a fly ash and 0.25 to 70 wt% of an alkaline earth metal sulfites (part of the sulphite salt is an alkaline earth <br/> gold Shoku硫 salt), mixed seawater A method for casting a cementitious mixture containing fly ash in the sea, which is characterized in that the slurry is poured into the sea. 2. The flow value of the slurry is 180 to 25.
The method of placing a cementitious mixture containing fly ash in the sea according to claim 1, wherein the method is 0 mm. 3. A dry weight of 10 to the cementitious mixture.
% Or less cement is mixed, this is kneaded with seawater to make a slurry, and this is cast in the sea, and the cementitious mixture containing fly ash according to claim 1 is cast in the sea.