Method for carbonizing and solidifying soil body by using low-carbon environment-friendly magnesium-based curing agent

Abstract

The invention discloses a method for carbonizing and solidifying a soil body by using a low-carbon environment-friendly magnesium-based curing agent, and belongs to the technical field of concrete. The method comprises the following steps: (1) mixing a to-be-solidified soil body with a curing agent according to a certain proportion to form a dry-mixed soil body; wherein the to-be-solidified soil body is sand and kaolin; the curing agent is magnesium oxide and magnesium bicarbonate; (2) mixing the dry-mixed soil body with water to form a slurry mixture, and then carrying out mold pressing to prepare a test block; and (3) sealing the test block, curing and maintaining, and obtaining a cured soil body after the age is reached. The invention has the advantages of low carbon, environmental protection, fast effectiveness, low cost and recyclability, and provides an efficient solution for replacing cement and a traditional carbonization technology.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and particularly to a method for carbonizing and solidifying soil with a low-carbon and environmentally friendly magnesium-based curing agent. Background Art

[0002] The cement industry is a typical high-carbon emission industry. The annual consumption of limestone in cement production is about 1.5 billion tons. As a non-renewable resource, the over-exploitation of limestone has caused ecological problems such as surface subsidence and loss of biodiversity. Therefore, the development of low-carbon material technology has become an urgent need for industry transformation.

[0003] The traditional magnesium oxide carbonization method is mainly applied in laboratory scenarios. In this method, the soil is placed in a carbon dioxide carbonization chamber or a certain pressure of gas is introduced through a carbon dioxide gas cylinder to complete carbonization. Due to problems such as gas injection efficiency, transmission uniformity, leakage control, equipment dependence, and product stability, this method is difficult to be widely promoted in actual engineering. Therefore, it is urgent to improve the existing technology to realize the engineering application of carbonization and solidification technology.

[0004] In the Chinese invention patent with the publication number CN115626806A, the inventor team provided a method for solidifying soil that is green, low-carbon, and environmentally friendly. In this method, magnesium oxide and baking soda are added to the soil, then water is added and mixed evenly, and after compaction and curing at normal temperature, the solidified soil is obtained, which solves the problems of uneven mixing and carbon dioxide leakage that may occur in the traditional magnesium oxide carbonization method when treating soil. The principle of this method includes the following reaction processes: 2NaOH + CO2 → Na2CO3 + H2O Na2CO3 + H2O + CO2 → 2NaHCO3 NaHCO3 + MgO + H2O → MgCO3·3H2O (hydromagnesite) + NaOH Or → Mg5(CO3)4(OH)2·5H2O (nesquehonite) + NaOH Or → Mg5(CO3)4(OH)2·4H2O (artinite) + NaOH The inventor team found in further research that sodium hydroxide is generated in the main reaction processes of this scheme. Sodium hydroxide is a strong base and is easily soluble in water, has corrosiveness and is difficult to recycle. Its leakage will cause water pollution. Sodium hydroxide must be neutralized with acid, and then new by-products are generated, which may cause secondary pollution.

[0005] In summary, a method for carbonizing and solidifying soil bodies is provided. While achieving low-carbon environmental protection, rapid effectiveness, and significantly reducing energy consumption and carbon dioxide emissions in civil engineering, it also takes into account recyclability and low pollution, which is of great significance for achieving the dual goals of material recycling and net emission reduction as well as the low-carbon transformation of civil engineering. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, in the first aspect of the present invention, a method for carbonizing and solidifying soil bodies with a low-carbon environmental protection magnesium-based curing agent that is easy to obtain raw materials, low in cost, simple in process, and rapid in effectiveness is provided, including the following steps: (1) Mix the soil body to be solidified with the curing agent according to a certain ratio to form a dry-mixed soil body; wherein, the soil body to be solidified is sand and kaolin; the curing agent is magnesium oxide and magnesium bicarbonate; (2) Mix the dry-mixed soil body with water to form a slurry mixture, and then form test blocks by molding; (3) The test blocks are sealed and cured, and the solidified soil body is obtained after reaching the age.

[0007] Preferably, in the step (1), the content of magnesium oxide in the curing agent is 2 wt.% - 10 wt.% of the soil body to be solidified.

[0008] Preferably, in the step (1), the molar ratio of magnesium oxide to magnesium bicarbonate in the curing agent is 1 - 10:2.

[0009] Preferably, in the step (1), magnesium bicarbonate is prepared by the following steps: magnesium hydroxide precipitate is formed by the reaction of magnesium oxide with water; the magnesium hydroxide precipitate is mixed with water to form a suspension; CO2 gas is introduced into the suspension to dissolve it, and the clarified magnesium bicarbonate solution is obtained after filtration, and magnesium bicarbonate is obtained after drying.

[0010] Preferably, in the step (2), the amount of water used accounts for 4 wt.% - 12 wt.% of the soil body to be solidified.

[0011] Preferably, in the step (3), the sealing condition is to wrap the test blocks with plastic wrap.

[0012] Preferably, in the step (3), the curing is carried out at room temperature, and the curing time is 1 - 7 d.

[0013] Preferably, the solidified soil body is heat-treated to regenerate magnesium oxide, and the recovered magnesium oxide is used as a component of the curing agent or as a raw material for producing magnesium bicarbonate for recycling.

[0014] In the second aspect of the present invention, a solidified soil body is provided, which is prepared by the method of the first aspect of the present invention.

[0015] In the third aspect of the present invention, there is provided an application of the solidified soil body of the second aspect of the present invention, specifically for replacing cement in civil engineering construction.

[0016] Based on the above technical solutions, the design concept and principle of the present invention are as follows: The present invention provides a method for carbonizing and solidifying soil bodies with a low-carbon and environmentally friendly magnesium-based solidifying agent. It is designed to use magnesium oxide and magnesium bicarbonate as solidifying agents to optimize the reaction path. Magnesium hydroxide is obtained by reacting magnesium oxide with water, and then magnesium bicarbonate is prepared by introducing CO2. This process absorbs CO2 gas, greatly reducing carbon emissions and achieving a low-carbon and environmentally friendly solidifying effect, which is of great significance for improving the environment. Compared with the traditional CO2 solidification method, a dry mixture is obtained by mixing magnesium oxide and magnesium bicarbonate, avoiding problems such as CO2 leakage and uneven carbonization. At the same time, not only CO2 is absorbed during the preparation of magnesium bicarbonate, but also CO2 in the air is absorbed during the solidification and curing stage. The preparation and use of magnesium bicarbonate in the present invention consume the generated CO2 and achieve the effect of solidifying soil bodies. No sodium hydroxide is produced in this reaction path, overcoming technical problems such as corrosion and pollution. In addition, the carbon sequestration ability of magnesium bicarbonate is stronger than that of sodium bicarbonate, and magnesium bicarbonate is also more stable than sodium bicarbonate, showing greater potential in the context of carbon neutrality. The present invention includes the following reaction processes: MgO + H2O → Mg(OH)2 Mg(OH)2 + 2CO2 → Mg(HCO3)2 Mg(HCO3)2 + MgO + H2O → MgCO3·3H2O (nesquehonite) or → Mg5(CO3)4(OH)2·5H2O (dypingite) or → Mg5(CO3)4(OH)2·4H2O (hydromagnesite) The solidified soil body of the present invention has good strength and is expected to replace traditional cement materials in the field of civil engineering. After heat treatment (such as calcination, etc.), the solidified soil body can regenerate magnesium oxide, which means that the magnesium oxide and magnesium bicarbonate soil specimens can be recycled. The calcination stage is the key step for the regeneration of magnesium oxide in the solidified soil. The magnesium carbonate compounds (such as nesquehonite, dypingite, hydromagnesite) in the solidified soil decompose thermally at high temperatures. Taking MgCO3·3H2O as an example, the chemical reaction formula for its calcination decomposition is: MgCO3·3H2O → MgO + CO2↑ + 3H2O↑ Through the above-mentioned approach, the regeneration of magnesium oxide is achieved. The magnesium oxide can be directly used as a curing agent component or as a raw material for producing magnesium bicarbonate and reused in soil solidification, forming a "solidification - calcination - regeneration" closed-loop cycle, which has better applicability in terms of recycling than the chemically active sodium hydroxide. Although calcination releases CO2, the overall amount of CO2 absorbed in the process is still greater than the emissions, thus completing the carbon recycling. This technology achieves the dual goals of material recycling and net emission reduction, providing an innovative solution for the low-carbon transformation of civil engineering.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention provides a method for carbonation curing soil with a low-carbon and environmentally friendly magnesium-based curing agent, which has the advantages of easily available raw materials, low cost, simple process, and quick effectiveness.

[0018] The present invention provides a solidified soil with good mechanical properties, which is recyclable and reusable.

[0019] The present invention provides an application of the solidified soil, which is expected to replace cement materials and has broad application prospects in the field of civil engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the unconfined compressive strength of the solidified soil under three curing conditions of Examples 1 - 6, Comparative Example 1, and Comparative Example 2. Figure 2 It is the pore size distribution of the 7-day solidified soil (stabilized solidified soil) with the molar ratios of magnesium oxide and magnesium bicarbonate being 5:1, 3:1, and 1:2 in the examples. Figure 3 It is the comparison chart of the porosity distribution of the 7-day solidified soil with the molar ratios of magnesium oxide and magnesium bicarbonate being 5:1, 3:1, and 1:2 in the examples. Figure 4 It is the X-ray diffraction (XRD) pattern of the 7-day solidified soil in Example 1.

[0021] Figure 5 It is the scanning electron microscope (SEM) pictures of the 7-day solidified soil in Example 1; among them, (a) is the SEM image magnified 2000 times, and (b) is the SEM image magnified 5000 times. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention will be further described below by way of examples, but the present invention is not limited thereto. The experimental methods without specific conditions in the following examples are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0023] Example 1 A method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based solidifying agent is as follows: (1) Mix the soil mass to be solidified with the solidifying agent according to a certain ratio to form a dry-mixed soil mass; among them, the soil mass to be solidified is sandy soil composed of sand and kaolin (9:1, m / m), and the sandy soil is dried and passed through a 2 mm sieve; the solidifying agent is magnesium oxide and magnesium bicarbonate, the content of magnesium oxide is 5 wt.% of the mass of the sandy soil, and the content of magnesium oxide and the content of magnesium bicarbonate are proportioned according to a molar ratio of 3:1; (2) Add the required water to the dry-mixed soil mass at a water content of 8 wt.% for wet mixing evenly to form a slurry mixture, and then use a micro-compactor to compact the slurry mixture in a cylindrical mold with a diameter of 50 mm and a height of 100 mm to obtain test blocks; (3) Wrap the test blocks with plastic wrap and cure them at room temperature (25 °C) for a certain period of time (1 d, 7 d), and demold them after reaching the age to obtain the solidified soil mass.

[0024] Example 2 The method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based solidifying agent in this example is basically the same as that in Example 1, except that the content of magnesium oxide and the content of magnesium bicarbonate in the solidifying agent are proportioned according to a molar ratio of 5:1.

[0025] Example 3 The method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based solidifying agent in this example is basically the same as that in Example 1, except that the content of magnesium oxide and the content of magnesium bicarbonate in the solidifying agent are proportioned according to a molar ratio of 4:1.

[0026] Example 4 The method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based solidifying agent in this example is basically the same as that in Example 1, except that the content of magnesium oxide and the content of magnesium bicarbonate in the solidifying agent are proportioned according to a molar ratio of 2:1.

[0027] Example 5 The method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based solidifying agent in this example is basically the same as that in Example 1, except that the content of magnesium oxide and the content of magnesium bicarbonate in the solidifying agent are proportioned according to a molar ratio of 1:1.

[0028] Example 6 The method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based solidifying agent in this example is basically the same as that in Example 1, except that the content of magnesium oxide and the content of magnesium bicarbonate in the solidifying agent are proportioned according to a molar ratio of 1:2.

[0029] Example 7 A method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based solidifying agent is as follows: (1) Mix the soil to be solidified and the curing agent in a certain proportion to form a dry-mixed soil mass. Among them, the soil to be solidified is sandy soil composed of sand and kaolin (9:1, m / m), and the sandy soil is dried and passed through a 2-mm sieve. The curing agent is magnesium oxide and magnesium bicarbonate. The content of magnesium oxide is 5 wt.% of the mass of the sandy soil, and the content of magnesium oxide and magnesium bicarbonate is proportioned at a molar ratio of 3:1. (2) Add the required water to the dry-mixed soil mass at a water content of 8 wt.% and mix evenly to form a slurry mixture. Subsequently, use a micro-compactor to compact the slurry mixture in a cylindrical mold with a diameter of 50 mm and a height of 100 mm to obtain test blocks. (3) Wrap the test blocks with plastic wrap and cure them at room temperature (25 °C) for a certain period of time (1 d, 7 d). After reaching the age, demold to obtain the solidified soil mass. Calcinate the solidified soil mass to regenerate magnesium oxide, recycle the magnesium oxide and use it as a component of the curing agent or as a raw material for producing magnesium bicarbonate for recycling.

[0030] Example 8 A method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based curing agent is as follows: (1) Mix the soil to be solidified and the curing agent in a certain proportion to form a dry-mixed soil mass. Among them, the soil to be solidified is sandy soil composed of sand and kaolin (9:1, m / m), and the sandy soil is dried and passed through a 2-mm sieve. The curing agent is magnesium oxide and magnesium bicarbonate. The content of magnesium oxide is 2 wt.% of the mass of the sandy soil, and the content of magnesium oxide and magnesium bicarbonate is proportioned at a molar ratio of 1:2. (2) Add the required water to the dry-mixed soil mass at a water content of 4 wt.% and mix evenly to form a slurry mixture. Subsequently, use a micro-compactor to compact the slurry mixture in a cylindrical mold with a diameter of 50 mm and a height of 100 mm to obtain test blocks. (3) Wrap the test blocks with plastic wrap and cure them at room temperature (25 °C) for a certain period of time (1 d, 7 d). After reaching the age, demold to obtain the solidified soil mass.

[0031] Example 9 A method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based curing agent is as follows: (1) Mix the soil to be solidified and the curing agent in a certain proportion to form a dry-mixed soil mass. Among them, the soil to be solidified is sandy soil composed of sand and kaolin (9:1, m / m), and the sandy soil is dried and passed through a 2-mm sieve. The curing agent is magnesium oxide and magnesium bicarbonate. The content of magnesium oxide is 10 wt.% of the mass of the sandy soil, and the content of magnesium oxide and magnesium bicarbonate is proportioned at a molar ratio of 5:1. (2) Add the required amount of water to the dry-mixed soil mass at a water content of 12 wt.% and mix it evenly to form a slurry mixture. Subsequently, use a micro-compactor to compact the slurry mixture in a cylindrical mold with a diameter of 50 mm and a height of 100 mm to obtain specimens. (3) Wrap the specimens with plastic wrap and cure them at room temperature (25 °C) for a certain period of time (1 d, 7 d). After reaching the age, demold them to obtain the cured soil mass.

[0032] Comparative Example 1 In this comparative example, cement is used as the curing component to cure the soil mass, and the method is as follows: (1) Mix the soil mass to be cured with cement (ordinary Portland cement of strength grade 42.5) according to a certain ratio to form a dry-mixed soil mass. Among them, the soil mass to be cured is sandy soil composed of sand and kaolin (9:1, m / m), and the sandy soil is dried and passed through a 2 mm sieve; the cement content is 5 wt.% of the mass of the sandy soil. (2) Add the required amount of water to the dry-mixed soil mass at a water content of 8 wt.% and mix it evenly to form a slurry mixture. Subsequently, use a micro-compactor to compact the slurry mixture in a cylindrical mold with a diameter of 50 mm and a height of 100 mm to obtain specimens. (3) Wrap the specimens with plastic wrap and cure them at room temperature (25 °C) for a certain period of time (7 d, 28 d). After reaching the age, demold them to obtain the cured soil mass, denoted as the cement group.

[0033] Comparative Example 2 In this comparative example, the traditional carbonization process is used to cure the soil mass, and the method is as follows: (1) Mix the soil mass to be cured with magnesium oxide according to a certain ratio to form a dry-mixed soil mass. Among them, the soil mass to be cured is sandy soil composed of sand and kaolin (9:1, m / m), and the sandy soil is dried and passed through a 2 mm sieve; the magnesium oxide content is 5 wt.% of the mass of the sandy soil. (2) Add the required amount of water to the dry-mixed soil mass at a water content of 8 wt.% and mix it evenly to form a slurry mixture. Subsequently, use a micro-compactor to compact the slurry mixture in a cylindrical mold with a diameter of 50 mm and a height of 100 mm to obtain specimens. (3) At room temperature, introduce carbon dioxide into the molded specimen at a pressure of 50 KPa to make the carbon dioxide gas fully mix with the soil mass until the mass of the specimen no longer increases. Complete carbonization takes 7 d. After 7 d, demold it to obtain the cured soil mass, denoted as the carbonization group.

[0034] Take the cured soil masses prepared in the above examples and comparative examples for performance testing: To determine the compressive strength of the specimens, a 20 kN compression testing machine was selected to measure the unconfined compressive strength of the specimens after 1 d and 7 d of curing. The test results of each group are as Figure 1 shown. By analyzing this figure, it can be seen that the compressive strength of the specimens increases with the increase of curing time; with the continuous increase of the molar ratio of MgO:Mg2(HCO3)2, it shows a trend of first increasing and then decreasing. When the molar ratio of MgO:Mg2(HCO3)2 is 3:1, the compressive strength of the specimens reaches the maximum. In addition, after 1 d of curing, the compressive strengths of the specimens with the molar ratios of MgO:Mg2(HCO3)2 of 3:1, 2:1, and 1:1 are significantly higher than those of the 28 d cement-solidified soil with the same dosage; after 7 d of curing, the compressive strength of the specimen with the molar ratio of MgO:Mg2(HCO3)2 of 3:1 reaches the strength of the 7 d carbonized specimen with the same dosage.

[0035] The T2 spectra of three different solidified soils with the molar ratios of magnesium oxide to magnesium bicarbonate of 5:1, 3:1, and 1:2 after 7 d were obtained by nuclear magnetic resonance spectroscopy (NMR), including the T2 relaxation time and intensity, and were transformed into the relationship between pore size (pore radius) and pore volume for analysis. The comparison of pore size distribution and porosity distribution is as Figure 2 , Figure 3 shown. When the molar ratio of magnesium oxide to magnesium bicarbonate is 5:1 and 1:2, the proportion of large-pore pores in the material is relatively high; when the molar ratio of magnesium oxide to magnesium bicarbonate is 3:1, the proportion of small-pore pores increases significantly, and the porosity of the specimen decreases. This may be because the reaction between magnesium oxide and magnesium bicarbonate fills the larger voids, forming a new pore size distribution, thereby increasing the strength of the material.

[0036] The group of soils treated with the molar ratio of magnesium oxide to magnesium bicarbonate of 3:1 was characterized by XRD, and the results are as Figure 4 shown. From Figure 4 analysis, it can be seen that significant quartz peaks and kaolinite peaks exist in the XRD patterns of the specimens, indicating that quartz and kaolinite are still the main components of the soil after the reaction of magnesium oxide and magnesium bicarbonate; hydromagnesite (MgCO3·3H2O), nesquehonite (Mg5(CO3)4(OH)2·4H2O), and lansfordite (Mg5(CO3)4(OH)2·5H2O) are formed in the specimens. Since the magnesium carbonate compounds have high cementing ability, they cement the soil particles together and penetrate into the voids between the soil particles to form a strength skeleton, making the structure more dense.

[0037] Figure 5SEM image of the sample cured for 7 days with the molar ratio of magnesium oxide to magnesium bicarbonate being 3:1. It can be observed from the image that more carbonized products are generated inside the sample, so the microstructure is relatively dense and the pores are small. This is because the higher the active content of magnesium oxide, the more products are generated, so the integrity of the microstructure of the carbonized solidified soil is stronger.

[0038] A method for carbonizing and solidifying soil body with a low-carbon and environmentally friendly magnesium-based curing agent proposed by the present invention meets the following design requirements: 1. Meet the actual engineering performance requirements; 2. The energy consumption and carbon emissions during the production process are both lower than those of cement; 3. The raw material cost is close to or lower than that of cement.

[0039] In summary, magnesium oxide and magnesium bicarbonate used in this patent have unique potential in the fields of carbon reduction and environmental protection and soil solidification, and the following advantages are worthy of attention: First, the solidified soil body can be calcined to regenerate magnesium oxide after curing, realizing the recycling of materials, which conforms to the environmental protection concept of "treating waste with waste"; second, magnesium oxide has a low cost and is easy to obtain; third, magnesium bicarbonate can directly participate in carbon sequestration, and can participate in the mineral carbonation reaction through the interaction with carbon dioxide, and finally convert gaseous CO2 into a solid mineral form to achieve long-term carbon sequestration.

[0040] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based solidifying agent, characterized in that, It includes the following steps: (1) Mix the soil to be solidified and the curing agent according to a certain ratio to form a dry-mixed soil body; wherein, the soil to be solidified is sand and kaolin; the curing agent is magnesium oxide and magnesium bicarbonate; (2) Mix the dry-mixed soil body with water to form a slurry mixture, and then form test blocks by molding; (3) The test blocks are sealed and cured, and the solidified soil body is obtained after reaching the age.

2. The method for carbonizing and solidifying soil mass with a low-carbon and environment-friendly magnesium-based solidifying agent according to claim 1, wherein: In the step (1), the content of magnesium oxide in the curing agent is 2 wt.% - 10 wt.% of the soil to be solidified.

3. The method for carbonizing and solidifying soil body with a low-carbon and environmentally friendly magnesium-based solidifying agent according to claim 1, characterized in that: In the step (1), the molar ratio of magnesium oxide to magnesium bicarbonate in the curing agent is 1 - 10:

2.

4. The method for carbonizing and solidifying soil body with a low-carbon and environmentally friendly magnesium-based solidifying agent according to claim 1, characterized in that, In the step (1), magnesium bicarbonate is prepared by the following steps: magnesium hydroxide precipitate is formed by the reaction of magnesium oxide with water; the magnesium hydroxide precipitate is mixed with water to form a suspension; CO2 gas is introduced into the suspension to dissolve it, and the clarified magnesium bicarbonate solution is obtained after filtration, and magnesium bicarbonate is obtained after drying.

5. The method for carbonizing and solidifying soil body with a low-carbon and environmentally friendly magnesium-based solidifying agent according to claim 1, characterized in that: In the step (2), the amount of water used accounts for 4 wt.% - 12 wt.% of the soil to be solidified.

6. The method for carbonizing and solidifying soil body with a low-carbon and environmentally friendly magnesium-based solidifying agent according to claim 1, characterized in that: In the step (3), the sealing condition is to wrap the test blocks with plastic wrap.

7. The method for carbonizing and solidifying soil body with the low-carbon and environment-friendly magnesium-based solidifying agent according to claim 1, characterized in that: In the step (3), the curing is carried out at room temperature, and the curing time is 1 - 7 d.

8. The method for carbonizing and solidifying soil mass with a low-carbon and environmentally friendly magnesium-based solidifying agent according to claim 1, characterized in that: The solidified soil body regenerates magnesium oxide after heat treatment, and the recovered magnesium oxide is used as a component of the curing agent or as a raw material for producing magnesium bicarbonate for recycling.

9. A solidified soil body, characterized in that: It is made by using the method described in any one of claims 1 - 8.

10. A solidified soil body as described in claim 9, characterized in that: It is used to replace cement in civil engineering construction.

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