JP2023059354A - Ash mortar, and method for constructing underwater structure using the same - Google Patents

Abstract

To provide an ash mortar that can secure a normal slope in a normal slope part of a submerged structure without using an additive and can ensure fluidity required for pumping during construction, and to provide a method for constructing an underwater structure using the ash mortar.SOLUTION: An ash mortar is a mixture of a solidification material, a coal ash and water to form an underwater structure 10A having a normal slope part 3A. The coal ash is composed of: a fly ash as a main component; and a clinker ash as a secondary component.SELECTED DRAWING: Figure 1

Description

The present invention relates to ash mortar using fly ash and clinker ash, which are coal ash, and a method for constructing an underwater structure with ash mortar.

Coal ash generated as a by-product of coal-fired power generation is roughly classified into fly ash and clinker ash. When pulverized coal is burned in a boiler in a coal-fired power plant, molten ash particles float in the high-temperature combustion gas, and as the temperature at the boiler outlet decreases, they become spherical fine particles. It becomes fly ash and is collected by an electrostatic precipitator. In addition, clinker ash is produced by coal ash particles generated by combustion inside the boiler, which coalesce together to form porous clumps that fall and accumulate in the clinker hopper (water tank) at the bottom of the boiler. It is crushed and dehydrated in a dehydration tank or the like, and then the particle size is adjusted with a sieve or the like depending on the application (see Non-Patent Document 1). Fly ash is spherical fine particles (see Non-Patent Document 2). Clinker ash is gravel-like and porous, and has excellent water retention, drainage, and air permeability. Most of its particles are fine pebbles and coarse sand, and the particle size distribution is similar to that of sand (see Non-Patent Document 3). . The chemical compositions of both fly ash and clinker ash are mainly composed of silica and alumina, and there is not much difference between them.

Some of these coal ash are landfilled as waste, but most of them are effectively used as admixtures for cement and concrete, and as various aggregates in civil engineering works. One of the effective utilization technologies is fly ash mortar. Fly ash mortar is used as a filling material for bank protection, a backfilling material, and a covering material for the backfilling material in port and harbor civil engineering works.

Patent Document 1 discloses that the coal ash utilization material used for landfilling in a controlled sea surface disposal site is a powdery mixture of fly ash and cement that is filled in a water-permeable and dust-proof bag. Since it is configured as a solid and solidifies after being put into water, it is possible to realize simplification in construction and space saving in the manufacturing yard (summary).

Japanese Patent Application Laid-Open No. 2020-190086

"Coal Ash Generation Amount and Production Process" Japan Fly Ash Association http://www.japan-flyash.com/process.html "Chemical and Physical Properties of Fly Ash" Japan Fly Ash Association http://www.japan-flyash.com/fchemiphysi.html "Chemical and Physical Properties of Clinker Ash" Japan Fly Ash Association http://www.japan-flyash.com/cchemiphysi.html

However, when fly ash mortar is used as a back-filling material or a covering material for the back-filling material, there is a problem that a predetermined slope cannot be secured because fly ash mortar has high fluidity. In order to solve this problem, techniques have been proposed to secure the gradient using additives such as thickeners, anti-separation agents, and hardening accelerators, but there is a concern about increased costs. In addition, when using in sea areas, it may be necessary to obtain permission to use the additive from relevant parties, and the procedures may be complicated. Also, in the actual construction work, it is necessary to secure the fluidity required for pumping. At present, when fly ash mortar is used as a backfilling material or coating material, fly ash is used alone without being mixed with clinker ash.

The coal ash utilization material of Patent Document 1 is to fill a water-permeable and dust-proof bag with a powdery mixture of fly ash and cement, and it is necessary to fill the bag with the mixture. , the filling process and material (bag body) are required, the process is complicated, and the material cost is high, which is disadvantageous in terms of cost.

In view of the problems of the prior art as described above, the present invention is capable of securing the slope of the slope of the underwater structure without using additives, and the fluidity required for pumping during construction. It is an object of the present invention to provide a secure ash mortar and a method for constructing an underwater structure with ash mortar.

An ash mortar for achieving the above object is an ash mortar obtained by mixing a solidifying material, coal ash, and water for forming an underwater structure having a slope, wherein the coal ash is the main component. It consists of fly ash and clinker ash as a subcomponent.

According to this ash mortar, since the coal ash is composed of fly ash as a main component and clinker ash as a secondary component, it is possible to secure a predetermined slope in the slope of the underwater structure without using additives. can. That is, by adding clinker ash, which has a relatively large particle size compared to fly ash, to fly ash as an aggregate, it becomes easier to form a particle skeleton in ash mortar. Forming properties are improved and a given slope can be achieved in the slope without the use of additives. The compounding ratio of fly ash, which is the main component, to clinker ash exceeds 50%.

It is preferable to mix the fly ash and the clinker ash in a mixing ratio of 9:1 to 8:2. The compounding ratio is the ratio of fly ash and clinker ash to the total weight of fly ash and clinker ash, and the same applies to the following description.

The solidifying material is preferably one, two or all of blast furnace slag cement, ordinary portland cement and fly ash cement.

The content of the solidifying material is preferably within the range of 50 kg/m ³ to 200 kg/m ³ .

When the flow value of the ash mortar after kneading is at least 88 mm, it is possible to secure the fluidity required for ash mortar pumping.

The water/powder ratio obtained by dividing the weight of the water by the total weight of the solidifying material and the coal ash is preferably within the range of 0.350 to 0.439.

The ash mortar can be used as a back-filling material for the underwater structure or a coating material for the back-filling material.

A method for constructing an underwater structure for achieving the above object is a method for constructing an underwater structure having a sloped portion using the above-described ash mortar, wherein the weight of the water is combined with the solidification material and the coal ash. At least the slope portion is constructed with the ash mortar in which the solidifying material, the coal ash, and the water are blended so that the water powder ratio divided by the total weight of the above is within a predetermined range.

According to this method for constructing an underwater structure, the slope section is constructed with ash mortar obtained by mixing solidifying material, coal ash (fly ash and clinker ash), and water so that the water/powder ratio is within a predetermined range. As a result, a predetermined slope can be secured in the slope without using additives.

In the method for constructing an underwater structure, the flow value of the ash mortar when pumping the ash mortar into the water for constructing the slope section can ensure the fluidity necessary for the pumping. is preferably at least the lower limit value.

In addition, the ash mortar obtained by blending the solidification material, the coal ash, and the water at a plurality of predetermined ratios was previously subjected to a blending test and an underwater placement experiment, whereby the flow value of the ash mortar and the slope portion A first relationship with the normal gradient and a second relationship between the flow value and the water powder ratio are obtained, respectively, and the water is calculated from the design value of the normal gradient based on the first and second relationships It is preferable to determine the powder ratio and use ash mortar blended based on the determined water/powder ratio.

It is preferable to adjust the water/powder ratio so that the normal gradient is in the range of 1:1.2 to 1:4.4.

In addition, it is preferable that the slope portion is a back-filling portion of the underwater structure or a covering portion of the back-filling portion.

According to the ash mortar and the method for constructing an underwater structure using ash mortar of the present invention, it is possible to secure the slope of the slope of the underwater structure without using additives, and it is necessary for pumping during construction. liquidity can be ensured.

FIG. 3 is a side sectional view showing an example of an underwater structure to which the ash mortar according to the present embodiment can be applied as a backfill material; FIG. 3 is a side cross-sectional view showing an example of an underwater structure to which the ash mortar according to the present embodiment can be applied as a covering material for a backfill material; It is the schematic which shows the underwater casting experiment situation used in this experiment example. 4 is a graph showing the relationship between the flow value and the placement gradient for ash mortar using only fly ash (FA) of this comparative example. 4 is a graph showing the relationship between the flow value and the placement gradient for ash mortar containing fly ash (FA) and clinker ash (CA) at a mixing ratio of 9:1 in this experimental example. 6 is a graph showing the relationship between the flow value and the water/powder ratio for ash mortar blended at a blending ratio of 9:1 similar to FIG. 5. FIG. 2 is a graph showing the relationship between the flow value and the placement gradient for ash mortar in which fly ash (FA) and clinker ash (CA) are blended at a blending ratio of 8:2 in this experimental example. 8 is a graph showing the relationship between the flow value and the water/powder ratio for ash mortar blended at a blending ratio of 8:2 similar to FIG. 7. FIG. It is a photograph which shows the external appearance of the substantially conical mountain|ridge part formed by the underwater casting experiment of this experiment example.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated. The ash mortar according to the present embodiment can be produced by mixing and kneading a solidifying material, coal ash, and water. It is suitable for forming an underwater structure with a steep slope.

The compounding ratio of fly ash to clinker ash exceeds 50%, but preferably the compounding ratio of fly ash to clinker ash is within the range of 9:1 to 8:2. This range roughly corresponds to the emission ratio of fly ash and clinker ash, which are coal ash generated and discharged as by-products in coal-fired power generation, so that fly ash and clinker ash can be efficiently and effectively used. can contribute to

The solidifying material may be one, two or all of blast furnace slag cement, ordinary portland cement and fly ash cement, and the amount of such solidifying material is 50 kg/m ³ to 200 kg/m ³ . is within the range of

In the ash mortar, the water/powder ratio obtained by dividing the weight of water by the total weight of the solidifying material and coal ash is preferably in the range of 0.350 to 0.439.

According to the ash mortar according to the present embodiment, most of the clinker ash particles are fine gravel and coarse sand, the particle size distribution is similar to that of sand, and the particle size is relatively large compared to fly ash. By adding fly ash as an aggregate, it becomes easier to form a particle skeleton. For this reason, it becomes easier to form a slope with ash mortar, and the slope formation characteristics are improved. realizable. In this way, since the coal ash is composed of fly ash as a main component and clinker ash as a secondary component, a predetermined slope can be secured in the slope portion of the underwater structure without using additives.

The ash mortar according to this embodiment is preferably used as a back-filling material for underwater structures or a coating material for the back-filling material. A back-filling portion of an underwater structure to which the ash mortar according to the present embodiment is applied and a covering portion of the back-filling portion will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a side sectional view showing an example of an underwater structure to which the ash mortar according to this embodiment can be applied as a backfill material. FIG. 2 is a side cross-sectional view showing an example of an underwater structure to which the ash mortar according to this embodiment can be applied as a covering material for backfilling.

As shown in FIG. 1, an underwater structure 10A according to the present embodiment includes a gravity caisson 1, a mound 2 on which the caisson 1 is installed on the bottom of the water G using riprap, and a caisson 1 having a predetermined slope. Backfilling part 3 constructed on the back side (bank side) of the backfilling part 3 and backfilling soil 4 constructed from earth and sand further on the bank side of the backfilling part 3, for example, constituting a bank protection structure or a quay wall structure be able to. By using the ash mortar of the present embodiment as the backfilling material for constructing the backfilling portion 3, the backfilling portion 3 having the normal gradient portion 3a with a predetermined normal gradient can be constructed.

The underwater structure 10B in FIG. 2 includes a caisson 1, a mound 2, a backfill portion 3, and a backfill soil 4, as in FIG. The back-filling part 3 is constructed from back-filling stones such as crushed stones, and the covering part 5 is constructed by covering the back-filling part 3 with a covering material. By using the ash mortar of the present embodiment as a covering material for constructing the covering portion 5, the covering portion 5 having the slope portion 5a having a predetermined slope can be constructed. A sand-proof sheet 6 is partially arranged on the shoulder portion of the upper end of the backfilling portion 3 on the bank side.

When constructing the back-filling part 3 in FIG. 1 and the covering part 5 of the back-filling part 3 in FIG. , the backfilling portion 3 of FIG. 1 and the covering portion 5 of FIG. 2 can be constructed so that the normal gradient portions 3a and 5a are within the range of 1:1.2 to 1:4.4. In other words, the water powder of ash mortar is added so that the normal gradient parts 3a and 5a in the backfilling part 3 in FIG. 1 and the covering part 5 in FIG. Adjust the ratio between 0.350 and 0.439.

The back-filling portion 3 in FIG. 1 and the coating portion 5 in FIG. 2 can be constructed by placing the ash mortar of this embodiment in water using a pump. It is necessary to have a value that can secure the necessary liquidity. In this case, if fly ash is used alone as coal ash, a particle skeleton is formed even with fly ash alone. Fluidity is reduced due to the consistency characteristics of , making it difficult to pump under pressure. There is no need to reduce the ratio (lower the water content ratio), the flow value does not decrease, fluidity can be secured, and pumping is facilitated. In addition, adding clinker ash to fly ash reduces the apparent liquidity limit wl of fly ash, which is advantageous in securing fluidity.

The relationship between pumpability and flow value (vane shear strength) varies depending on the pump capacity. In the case of mortar, the lower limit of the flow value is about 88 mm, and in the case of ash mortar, which is also blended at a blending ratio of 8:2, the lower limit of the flow value is about 92 mm. Also, focusing on ensuring workability in water (inseparability in water, fluidity), the above numerical values are the lower limit of the flow value as a state that is neither too hard nor too soft.

According to this embodiment, the ash mortar is required to improve the slope formation characteristics and to ensure fluidity for pumping. As for the latter, it is necessary to satisfy the two conflicting conditions of fluidity (softness) that allows pumping. By increasing the thickness of the ash mortar, it is possible to improve the slope formation characteristics without simply making the ash mortar harder (lowering the fluidity).

In addition, as in Patent Document 1, in a construction method using a water-permeable and dust-proof bag filled with a powdery mixture of fly ash and cement, it is necessary to stack a large number of bags in the back-filling part or the like. However, according to this embodiment, the ash mortar is pumped by a pump and placed in water, so that the cost can be reduced.

(Experimental example)
Next, the present invention will be described with experimental examples. In this experimental example, fly ash and clinker ash mixed at a mixing ratio of 9:1 and 8:2, and cement and seawater with different mixing ratios were kneaded to prepare multiple types of ash mortar, and a mixing test was performed. The flow value immediately after kneading was measured. Blast furnace slag cement type B, ordinary Portland cement, or fly ash cement is used as the cement, and the blending amount is 50 kg/m ³ to 200 kg/m ³ . The flow test was performed based on Cylinder Flow Test: Test Method 313 (NEXCO Test Method Volume 3 Concrete-Related Test Methods). In addition, using ash mortar with a plurality of formulations determined from the above formulation test, an underwater placement experiment as shown in FIG. As shown in FIG. 3, ash mortar was poured from a hose into water in a water tank to form a substantially conical ridge as shown in FIG.

As a comparative example, Fig. 4 shows the relationship between the flow value obtained from the blending test and the casting gradient obtained from the underwater casting test for ash mortar using only fly ash (FA). In this comparative example, the sample with a flow value of about 85 mm could not be tested because the fluidity was too low. My guess is 80mm. However, at a flow value of 80 mm, the fluidity required for pumping cannot be secured, and from the viewpoint of pumping performance, ash mortar using only fly ash cannot secure a casting gradient of 1:1.2.

Next, for ash mortar containing fly ash (FA) and clinker ash (CA) at a mixing ratio of 9:1, flow values obtained from mixing tests and casting gradients obtained from underwater casting experiments is shown in FIG. From Fig. 5, it can be seen that the flow value of ash mortar should be set to 88 mm when the casting slope is to be 1:1.2, and the flow value should be set to 180 mm when the casting slope is to be 1:4.4.

As shown in Fig. 5, when the flow value of the ash mortar is 88 mm, it is possible to secure the fluidity necessary for the pump placement and achieve a placement gradient of 1:1.2.

Fig. 6 shows the relationship between the flow value obtained from the blending test and the water/powder ratio for the ash mortar blended with fly ash (FA) and clinker ash (CA) at a blending ratio of 9:1. . From FIG. 6, it can be seen that the water/powder ratio should be adjusted to 0.364 when the flow value of the ash mortar is desired to be 88 mm, and the water/powder ratio should be adjusted to 0.439 when the flow value is desired to be 180 mm.

Table 1 below shows examples of ash mortar in which fly ash (FA) and clinker ash (CA) are blended at a blending ratio of 9:1, with water/powder ratios of 0.364 and 0.439.

Next, for ash mortar containing fly ash (FA) and clinker ash (CA) at a mixing ratio of 8:2, the flow value obtained from the mixing test and the casting gradient obtained from the underwater casting test is shown in FIG. From Fig. 7, it can be seen that the flow value of ash mortar should be set to 92 mm if the casting slope is to be 1:1.2, and that the flow value should be set to 163 mm if the casting slope is to be 1:3.8. When the flow value of the ash mortar with the above mixture is 92mm, it is possible to secure the fluidity necessary for pumping and realize a casting gradient of 1:1.2.

Fig. 8 shows the relationship between the flow value obtained from the blending test and the water/powder ratio for the ash mortar blended with fly ash (FA) and clinker ash (CA) at a blending ratio of 8:2. . From FIG. 8, it can be seen that the water/powder ratio should be adjusted to 0.350 when the flow value of the ash mortar is desired to be 92 mm, and the water/powder ratio should be adjusted to 0.419 when the flow value is desired to be 163 mm.

Table 2 below shows examples of ash mortar containing fly ash (FA) and clinker ash (CA) at a mixing ratio of 8:2, with water/powder ratios of 0.350 and 0.419.

From the results of the above experimental examples, the water/powder ratio of the ash mortar used in the blending test and the underwater placement test was in the range of 0.350 to 0.439. When the compounding ratio of fly ash (FA) and clinker ash (CA) is 9:1, the flow value is in the range of 88 mm to 180 mm when the water/powder ratio is in the range of 0.364 to 0.439. When the compounding ratio is 9:1, the submerged casting gradient is 1:1.2 to 4.4 when the flow value is in the range of 88mm to 180mm. Also, when the compounding ratio is 8:2, the flow value is in the range of 92 mm to 163 mm when the water/powder ratio is in the range of 0.350 to 0.419. When the compounding ratio is 8:2, the submerged casting gradient is 1:1.2 to 3.8 when the flow value is in the range of 92mm to 163mm.

From the above, for ash mortar in which clinker ash is blended in the range of 10 to 20% of fly ash, the placement gradient can be set to the target value (design value) by adjusting the water/powder ratio. The fluidity required for pumping can be secured. When the blending ratio of fly ash and clinker ash is 9:1, by setting the water/powder ratio of the ash mortar to 0.364-0.439, it is possible to cast at a slope of 1:1.2-4.4. Also, when the compounding ratio is 8:2, setting the water/powder ratio of the ash mortar to 0.350-0.419 enables the placement at a slope of 1:1.2-3.8.

In the above experimental example, the amount of the solidifying material was set to 50 kg, but the same results were obtained in the flow test for the test specimens in which the amount of the solidifying material was set to 200 kg.

Although the embodiments for carrying out the present invention have been described above, the present invention is not limited to these, and various modifications are possible within the scope of the technical idea of the present invention. For example, the underwater structures shown in FIGS. 1 and 2 can constitute a revetment structure or a quay wall structure, but are not limited to this, and can also constitute, for example, a bank structure. Further, a structure using a steel plate cell instead of the caisson shown in FIGS. 1 and 2 may be used.

In addition, fly ash is blended in a blending ratio exceeding 50% with respect to clinker ash. It is possible to grasp the degree of influence of the mixing ratio of and on the flow value.

According to the present invention, the predetermined slope of the slope of the underwater structure can be secured without using additives, cost reduction can be achieved, and complicated procedures such as permission to use additives are unnecessary. Also, since the fluidity necessary for pump driving during construction can be secured, good workability can be realized.

1 caisson 2 mound 3 backfilling part 3a slope part 5 covering part 5a slope part 10A, 10B underwater structure G water bottom

Claims (11)

An ash mortar obtained by mixing a solidifying material, coal ash, and water for forming an underwater structure having a slope,
The coal ash is an ash mortar composed of fly ash as a main component and clinker ash as an auxiliary component. 2. The ash mortar according to claim 1, wherein said fly ash and said clinker ash are blended in a blending ratio of 9:1 to 8:2. 3. The ash mortar according to claim 1 or 2, wherein the solidifying material is any one, two or all of blast furnace slag cement, ordinary portland cement and fly ash cement. 4. The ash mortar according to any one of claims 1 to 3, wherein the amount of said solidifying agent is within the range of 50 kg/m ³ to 200 kg/m ³ . The ash mortar according to any one of claims 1 to 4, wherein the flow value after kneading the ash mortar is at least 88 mm. The ash mortar according to any one of claims 1 to 5, wherein the water/powder ratio obtained by dividing the weight of said water by the total weight of said solidifying material and said coal ash is within the range of 0.350 to 0.439. The ash mortar according to any one of claims 1 to 6, wherein the ash mortar is used as a back-filling material for the underwater structure or a coating material for the back-filling material. A method for constructing an underwater structure having a slope using the ash mortar according to any one of claims 1 to 7,
The ash mortar in which the solidifying material, the coal ash, and the water are blended so that the water/powder ratio obtained by dividing the weight of the water by the total weight of the solidifying material and the coal ash is within a predetermined range. A method for constructing an underwater structure for constructing the slope section. 8. A flow value of said ash mortar when pumping said ash mortar into water for constructing said slope section is equal to or higher than a lower limit value capable of ensuring fluidity necessary for said pumping. 2. The method for constructing an underwater structure according to 1. For the ash mortar obtained by blending the solidifying material, the coal ash, and the water at a plurality of predetermined ratios, a blending test and an underwater placement test were performed in advance to determine the flow value of the ash mortar and the slope of the slope. and a second relationship between the flow value and the water powder ratio, respectively;
10. The ash mortar according to claim 8 or 9, wherein the water/powder ratio is obtained from the design value of the normal gradient based on the first and second relationships, and the ash mortar blended based on the obtained water/powder ratio is used. A method of constructing an underwater structure. The method for constructing an underwater structure according to any one of claims 8 to 10, wherein the water/powder ratio is adjusted so that the normal gradient is in the range of 1:1.2 to 1:4.4.

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