Construction method using clay slurry

Abstract

To realize a new construction method using clay slurry that can reduce the separation of carbon materials.SOLUTION: The present invention includes a first mixing step of producing a first clay slurry by mixing clay and a carbon material, a second mixing step of producing a second clay slurry having a lower viscosity than the first clay slurry by mixing the first clay slurry with water and a hardening material, and a pumping step of pumping the second clay slurry to a target location.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a construction method using clay slurry.

Background Art

[0002] Patent Document 1 describes a ground material using soft soil, which is a mixture containing soft soil and granular material, and the mixture exhibits strain hardening behavior under the action of shear force under consolidated undrained conditions, and a ground improvement method using the ground material for soil structures.

[0003] Patent Document 2 describes a soil paving material containing cement, calcium sulfite with a pH of 9.0 or more, a redox potential of 50 mV or less, an Mg content of 0.5 to 2.0% in terms of MgO, calcium aluminate with a vitrification rate of 70% or more, a CaO / Al2O3 molar ratio of 1.0 to 2.7, and an impurity content of 15% or less, and a method of putting the soil paving material on a foundation ground.

[0004] Patent Document 3 describes a soil improvement method for highly water-containing soil, in which a soil improvement material mainly composed of an inorganic material that causes at least one of water evaporation by an exothermic reaction and formation of a consolidated product by a chemical reaction is added to the highly water-containing soil, and the highly water-containing soil is solidified into improved soil by stirring and mixing, and in the soil improvement method, the inorganic material contains iron powder, carbon powder, and salt.

[0005] Patent Document 4 describes a ground improvement method in which a soil neutralizing agent obtained by mixing 10 to 100% by weight of an acidic solidification aid with 100 parts by weight of magnesium oxide and a water absorbent are used in combination to form improved soil, and the improved soil is injected into the soil to be treated in a poor ground or a soft ground, and activated carbon is used as the water absorbent.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] Efforts are underway towards a decarbonized society aiming for zero carbon dioxide emissions, and the construction industry is also required to reduce its carbon dioxide emissions. Carbon neutrality is one of the efforts towards decarbonization in response to global warming. Carbon neutrality is an effort aimed at achieving "substantially zero" carbon dioxide emissions by offsetting the amount of carbon dioxide emissions with the amount of absorption.

[0008] Therefore, also in the construction method, in order to bring the carbon dioxide emissions closer to "substantially zero", it is required to incorporate a process that can increase the amount of carbon dioxide absorption by using a material that absorbs carbon dioxide and immobilizing it.

[0009] However, Patent Documents 1 and 2 mentioned above do not disclose anything about mixing a carbon material into a clay slurry and a construction method using a clay slurry containing a carbon material.

[0010] Also, Patent Documents 3 and 4 mentioned above do not disclose anything about the problems when mixing a carbon material into a clay slurry and using it in a construction method.

[0011] However, when a carbon material is mixed into a slurry of a hardening material, there is a problem that the carbon material floats up from the hardening material slurry and the carbon material and the slurry separate.

[0012] One aspect of the present invention has been made in view of the above problems, and an object thereof is to realize a new construction method using a clay slurry that can reduce the separation of carbon materials.

Means for Solving the Problems

[0013] In order to solve the above problems, a construction method according to one aspect of the present invention is a construction method using a clay slurry, and includes a first mixing step of generating a first clay slurry by mixing clay and a carbon material, and a second mixing step of generating a second clay slurry having a lower viscosity than the first clay slurry by mixing water and a curing material into the first clay slurry, and a pumping step of pumping the second clay slurry to a target point by a pump.

Effects of the Invention

[0014] According to one aspect of the present invention, there is an effect that a new construction method using a clay slurry that can reduce the separation of carbon materials can be realized.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0016] <Construction Method> A construction method according to one aspect of the present invention is a construction method using a clay slurry, which includes a first mixing step of generating a first clay slurry by mixing clay and a carbon material, and a second mixing step of generating a second clay slurry having a lower viscosity than the first clay slurry by mixing water and a curing agent into the first clay slurry, and a pumping step of pumping the second clay slurry to a target location by a pump.

[0017] The second clay slurry is generated from the first clay slurry, contains clay, a carbon material, a curing agent, and water, and has a lower viscosity than the first clay slurry. By pumping and injecting the second clay slurry into a target location, backfilling and landfill ground can be created. The construction method according to one aspect of the present invention can be a ground improvement construction method.

[0018] FIG. 1 is a schematic diagram for explaining a construction system 100 for performing a construction method according to one aspect of the present invention. FIG. 2 is a diagram for explaining an overview of a first mixing step and a second mixing step included in the construction method according to one aspect of the present invention.

[0019] As shown in FIG. 1, the construction system 100 is a system for injecting a clay slurry, and includes a slurry plant 10 for manufacturing a first clay slurry and a second clay slurry, and a pump 20 for pumping the second clay slurry to a target location.

[0020] The slurry plant 10 preferably includes a measuring unit 11, a mixer 13, and a flow meter 15, and an agitator 14 and a pump P. The pump P pumps the second clay slurry to the pump 20.

[0021] The measuring unit 11 measures a carbon material, water, a curing agent described later, and an admixture added as necessary.

[0022] 〔First mixing step〕 Fig. 2(a) shows an outline of a first mixing step included in a construction method according to an embodiment. As shown in Fig. 2(a), in the first mixing step, the clay measured by the measuring unit 11 and the carbonaceous material may be mixed by the mixer 13. Thereby, it is preferable to generate a first clay slurry in which the carbonaceous material is dispersed so that the particle surface of the carbonaceous material is covered with the clay. In addition to the clay and the carbonaceous material, a mixing agent may be mixed into the first clay slurry.

[0023] The clay may be any one of natural clay, dredged clay, and construction-generated soil, or a mixed soil of any of these natural clay, dredged clay, and construction-generated soil.

[0024] When using natural clay, it is preferably highly viscous clay having high viscosity, and bentonite is the most preferable natural clay. It is more preferable that the natural clay is mined and processed and does not contain sand.

[0025] The dredged clay may be clay dredged around the construction target site and supplied to the mixer 13, and the construction-generated soil may be soil generated as a construction by-product in construction work and civil engineering work. When the clay is selected from dredged clay and construction-generated soil, or is a mixed soil of dredged clay and construction-generated soil, the ground improvement construction method according to one aspect of the present invention can be a ground improvement construction method that reuses dredged clay and construction-generated soil.

[0026] When the clay is dredged clay, the dredged clay may be clay dredged around the construction target site and supplied to the mixer 13, and for example, gravel, sand, etc. may be separated from the dredged clay.

[0027] When the clay is construction-generated soil, the construction-generated soil may be clay selected from first to fourth types of construction-generated soil and muddy soil.

[0028] It is preferable to adjust the viscosity of the first clay slurry after mixing the carbon material so that the table flow value is 80 mm or more and 110 mm or less. To adjust the table flow value of the first clay slurry, if the table value of the raw material slurry is less than 80 mm, water may be added, and if the table flow value of the first clay slurry is greater than 110 mm, clay may be added. Thereby, the dispersion stability of the carbon material in the first clay slurry can be enhanced, and further, the separation of the carbon material in the second clay slurry described later can be prevented.

[0029] For reference, the table flow value of the first clay slurry of 80 mm or more and 110 mm or less corresponds to a vane shear strength of 0.5 to 1.5 kN / m 2 or so.

[0030] The carbon material has a porous structure and a bulk density as small as about 0.4 g / cm 3 When such a carbon material with a small bulk density is simply mixed with the clay slurry, the carbon material floats in the clay slurry and the carbon material and the clay slurry are separated. According to the construction method according to one embodiment, by performing the first mixing step, the surface of the carbon material particles is coated with clay, so that the dispersion stability of the carbon material in the clay slurry can be enhanced, and the separation of the carbon material and the clay slurry can be prevented.

[0031] The carbon material to be mixed with the clay is preferably so-called biochar derived from plants grown by absorbing carbon dioxide from the viewpoint of carbon neutrality. Examples of biochar include bamboo charcoal, charcoal, and rice husk charcoal. Among biochars, bamboo is preferable because it grows fast and the cycle of felling & tree planting is also fast, from the viewpoint that CO2 absorption is efficiently performed.

[0032] From the perspective of preventing separation due to the floating of the carbonaceous material in the first clay slurry, the carbonaceous material may be pulverized in advance. When pulverizing the carbonaceous material in advance, it is preferable to pulverize the carbonaceous material so that it passes through a sieve having an opening of 5 mm or 2 mm. As the sieve for evaluating the particle size of the pulverized carbonaceous material, a sieve conforming to JIS Z8801-1 may be used in either case where the particle size of the carbonaceous material is 5 mm or less or 2 mm or less. For example, the carbonaceous material passing through a sieve having an opening of 2 mm may have an average particle size (D50) of about 1 mm, and in the second clay slurry, the separation of the carbonaceous material can be further suppressed.

[0033] The amount of the carbonaceous material finally contained in the second clay slurry is such that the weight of the carbonaceous material is 150 kg or more and 300 kg or less per 1 m of the total of clay, water, and hardening material. 3 By setting the amount of the carbonaceous material to 150 kg or more, a second clay slurry capable of being immobilized using a material that absorbs carbon dioxide can be obtained, and the target site can be landfilled with the second clay slurry.

[0034] 〔Second mixing step〕 In the second mixing step, the water and hardening material measured by the measuring unit 11 are supplied to the mixer 13, and the water and hardening material are mixed with the first clay slurry generated in the mixer 13 in the first mixing step. Thereby, as shown in Fig. 2(b), a second clay slurry in which the carbonaceous material is stably dispersed with the clay contained in the first clay slurry coating the particle surface of the carbonaceous material can be generated.

[0035] The hardening material mixed in the second clay slurry is typically cement, which may be Portland cement, blast furnace cement containing blast furnace slag, fly ash cement, etc. Further, the hardening material may be a neutral hardening material containing magnesium oxide and an acidic hardening aid such as aluminum sulfate. Also, the water used in the second clay slurry is not limited and may be fresh water, brackish water, or seawater.

[0036] In the second mixing step, the table flow value and density of the second clay slurry may be adjusted by adjusting the contents of the hardening material and water.

[0037] In the second mixing step, it is preferable to adjust the table flow value of the second clay slurry to be 110 mm or more and 400 mm or less. The adjustment of the table flow value of the second clay slurry can be performed, for example, by adding water if the table flow value is less than 110 mm, or by adding a hardening material if the table flow value is greater than 400 mm. Thereby, while enhancing the fluidity when pumping by the pump P, it is possible to further prevent the carbon material from separating in the second clay slurry. Also, when pumping with the pump P, the second clay slurry can be pumped to the target location without applying excessive pressure.

[0038] For reference, a table flow value of 110 mm or more and 400 mm or less of the second clay slurry corresponds to a vane shear strength of about 0.1 to 0.5 kN / m 2 to some extent.

[0039] Also, in the second mixing step, the density of the second clay slurry is preferably adjusted to 1.1 g / cm 3 or more and 1.3 g / cm 3 or less. The adjustment of the density of the second clay slurry can be performed, for example, by adding a hardening material if the density is less than 1.1 g / cm 3 , or by adding water if the density is greater than 1.3 g / cm 3 . Thereby, it is possible to further prevent the carbon material from separating in the second clay slurry, and it is possible to reduce the weight of the improved soil and landfill generated from the second clay slurry.

[0040] In the second mixing step, with the water content contained in the second clay slurry and the weight of the hardening material as 100%, the weight of the water mixed with the hardening material is preferably adjusted to 50% or more and 100% or less, and more preferably 80% to 100% or less.

[0041] Also, from another perspective, the fluidity of the second clay slurry in the pump pumping stage, that is, the table flow value (or vane shear strength), and the target strength at 28 days in the second clay slurry are evaluated in advance, and from the fluidity and the target strength at 28 days, the mixing amounts of water, carbon material, and hardening material to be mixed into the second clay slurry may be determined in advance. At this time, an amount of water corresponding to a part of the predetermined mixing amount may be mixed into the above-mentioned first clay slurry to adjust the table flow value or vane shear strength of the above-mentioned first clay slurry. Then, an amount of water obtained by subtracting the amount of water mixed into the first clay slurry from the mixing amount of water to be mixed into the second clay slurry determined in advance is mixed to obtain the second clay slurry in the second mixing step. Thereby, while achieving both control of the dispersibility of the carbon material in the first clay slurry and control of the fluidity of the second clay slurry, the strength in ground improvement such as backfill formed by the second clay slurry can also be designed.

[0042] In the second mixing step, the second clay slurry may contain admixtures such as thickeners, high-performance water reducers, high-performance AE water reducers, and fluidizing agents, and thereby the viscosity of the second clay slurry may be adjusted.

[0043] The second clay slurry can be transferred from the mixer 13 to the agitator 14 and supplied to the target location.

[0044] The flowmeter 15 can measure the flow rate of the second clay slurry supplied from the agitator 14 and transmit the flow rate data to the measuring unit 11. The measuring unit 11 may manage the flow rate of the second clay slurry sent to the pump 20 based on the flow rate data.

[0045] 〔Pumping Process〕 The construction method according to one embodiment includes a pumping step of pumping a second clay slurry to a target location by a pump P. In the pumping step, by pumping a second clay slurry with less clay than the first clay slurry, the second clay slurry can be supplied to the target location without applying excessive pressure by the pump P. The second clay slurry supplied to the target location can be used to create a landfill, ground, or the like.

[0046] The target location to be constructed can be a space for ground construction, and can be a location where the ground 50 is constructed as illustrated in FIG. 1. The target location for ground construction illustrated in FIG. 1 may be in the underwater part. For example, when the target location is underwater, the construction method according to one embodiment can be a construction method for creating new land such as landfill.

[0047] 〔Construction method according to another embodiment〕 The construction method according to one embodiment is not limited to the above embodiment. FIG. 3 is a diagram for explaining the outline of the backfill part of the revetment part, which is the target location, where the construction method according to one aspect is performed. As shown in FIG. 3, in the construction method according to another embodiment, the target location of the construction may be the backfill part 3 on the back side of the revetment.

[0048] As shown in FIG. 3, the underwater structure 60 constituting the revetment structure or the quay wall structure can be used as the target location. The underwater structure 60 includes a gravity caisson 61, a mound 62 constructed on the bottom G with riprap and on which the caisson 61 is installed, a backfill part 63 constructed on the back side (shore side) of the caisson 61 so as to have a predetermined slope, and a backfill soil 64 constructed from earth and sand further on the shore side of the backfill part 63.

[0049] In the construction method according to one embodiment, since the second clay slurry has a lower density than the conventional clay slurry by containing a carbonaceous material, the backfill portion 63 with a low density can be formed by manufacturing the backfill portion 63 with the second clay slurry. Further, in the second clay slurry, the carbonaceous material is dispersed and stabilized and uniformly mixed. Therefore, while withstanding the load of the backfill soil 64, the horizontal pressure applied to the caisson 61 can be reduced by the load of the backfill portion 63. Thus, a construction method of forming the backfill of the retaining wall back or the revetment back, or the ground of the landfill site with the second clay slurry is also within the scope of the present invention.

[0050] Note that in the construction method according to one embodiment, the construction-generated soil generated when constructing the underwater structure 60 may be used for the first clay slurry.

[0051] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0052] 〔Summary〕 The construction method according to Aspect 1 of the present invention is a construction method using a clay slurry, including a first mixing step of generating a first clay slurry by mixing clay and a carbonaceous material, and a second mixing step of generating a second clay slurry having a lower viscosity than the first clay slurry by mixing water and a curing agent into the first clay slurry, and a pumping step of pumping the second clay slurry to a target point by a pump.

[0053] According to the above aspect, the clay contained in the first clay slurry with high viscosity can coat the particle surface of the carbonaceous material with clay, and the dispersion stability of the carbonaceous material can be enhanced in the second clay slurry with lower viscosity. Thereby, it is possible to prevent the carbonaceous material from separating with the second clay slurry and ensure the fluidity of the second clay slurry when pumping by a pump.

[0054] Moreover, in the construction method according to Embodiment 2 of the present invention, in the construction method described in the above Embodiment 1, it is preferable that the table flow value of the first clay slurry is 80 mm or more and 110 mm or less, and the table flow value of the second clay slurry is 110 mm or more and 400 mm or less.

[0055] According to the above aspect, the clay contained in the first clay slurry can be coated on the surface of the carbon material particles, and furthermore, the fluidity of the second clay slurry can be increased.

[0056] Moreover, in the construction method according to Embodiment 3 of the present invention, in the construction method described in the above Embodiment 1 or 2, the density of the second clay slurry is adjusted to be 1.1 g / cm 3 or more and 1.3 g / cm 3 or less. The density of the second clay slurry is preferably adjusted to be 1.1 g / cm 3 or more and 1.3 g / cm 3 or less.

[0057] According to the above aspect, while preventing the separation of the carbon material in the second clay slurry, it is possible to reduce the weight of the structure formed by the second clay slurry at the target location.

[0058] Moreover, in the construction method according to Embodiment 4 of the present invention, in the construction method described in the above Embodiment 3, both or one of the table flow value and the density of the second clay slurry may be adjusted by the mixing amounts of water and hardening material in the second mixing step.

[0059] According to the above aspect, while preventing the separation of the second clay slurry, it is possible to ensure the fluidity of the second clay slurry when pumping it by a pump.

[0060] Moreover, in the construction method according to aspect 5 of the present invention, in the construction method described in any of the above aspects 1 to 4, in the first mixing step, the clay mixed with the carbonaceous material is any one of dredged clay, construction-generated soil, and natural clay, or clay in which any two or more of the dredged clay, the construction-generated soil, and the natural clay are mixed, and the natural clay is preferably bentonite.

[0061] According to the above aspect, by using dredged clay and construction-generated soil, it can be implemented as a ground improvement construction method for reusing them, and by using natural clay, the dispersion stability of the carbonaceous material can be further enhanced.

[0062] Further, in the construction method according to aspect 6 of the present invention, in the construction method described in any of the above aspects 1 to 5, when the target site is a landfill behind a bulkhead or a revetment, the second clay slurry pumped can be used to backfill behind the bulkhead or the revetment, or to create a landfill site.

[0063] According to the above aspect, at the target site, a ground lightened by the second clay slurry containing a carbonaceous material can be created.

Industrial Applicability

[0064] The present invention can be used for ground improvement and construction such as backfilling behind bulkheads and revetments, and landfilling.

Explanation of Signs

[0065] 10 Slurry plant 11 Measuring unit 13 Mixer 14 Agitator 15 Flowmeter 20 Pump 50 Ground (input to the target site) 60 Submerged structure (target site) 63 Backfilled part (target site) 100 Construction system

Claims

1. A construction method using a clay slurry, comprising: a first mixing step of producing a first clay slurry by mixing clay and a carbon material; a second mixing step of producing a second clay slurry having a lower viscosity than the first clay slurry by mixing water and a curing agent into the first clay slurry; a pumping step of pumping the second clay slurry to a target location by a pump.

2. The table flow value of the first clay slurry is 80 mm or more and 110 mm or less; The table flow value of the second clay slurry is 110 mm or more and 400 mm or less. The construction method according to Claim 1.

3. Adjust the density of the second clay slurry to be 1.1 g / cm ３ or more and 1.3 g / cm ３ or less. The construction method according to claim 2.

4. The construction method according to Claim 3, wherein both or one of the table flow value and the density of the second clay slurry are adjusted by the mixing amounts of water and the curing agent in the second mixing step.

5. In the first mixing step, the clay mixed with the carbon material is any one of dredged clay, construction-generated soil, and natural clay, or a clay in which any two or more of the dredged clay, the construction-generated soil, and the natural clay are mixed; The natural clay is bentonite. The construction method according to Claim 1.

6. The target location is the back of a retaining wall, or the backfill of a revetment, or landfill ground; The construction method according to any one of Claims 1 to 5, wherein the pumped second clay slurry is used to form the back of a retaining wall, the backfill of a revetment, and landfill ground.

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