Solidifying liquid for fluid-state solidified soil and preparation method of solidifying liquid

Abstract

The invention provides curing liquid for fluid-state cured soil and a preparation method of the curing liquid. The method comprises the following steps: step 1, carrying out coordination reaction on 18-crown-6 and sodium silicate in water to obtain a complex solution; step 2, slowly adding sodium hypochlorite into the complex solution, and adjusting the pH value to be alkaline to obtain an alkaline solution; and step 3, heating and stirring the alkaline solution, and cooling to obtain the curing liquid for the fluid-state cured soil. The curing liquid not only improves the curing effect and the mechanical property of the fluid-state cured soil, but also can reduce environmental pollution, and the preparation method is simple and convenient to operate, low in cost and suitable for large-scale application.

Description

Technical Field

[0001] The invention belongs to the field of environmental engineering, and in particular relates to a solidifying liquid for fluidized solidified soil and a preparation method thereof. Background Art

[0002] As my country's infrastructure construction continues to expand and deepen, the demand for high-quality soil reinforcement materials is increasing across various road, building, and infrastructure projects. As a new type of soil reinforcement material, fluidized soil has gained widespread application in engineering due to its significant advantages, including high strength, good fluidity, convenient construction, and minimal environmental impact. In road construction, fluidized soil can be used for paving road bases, effectively improving the bearing capacity and stability of road structures. In construction projects, fluidized soil can be used for foundation treatment, providing a solid and reliable foundation for buildings.

[0003] However, fluidized soil reinforcement still has certain limitations in practical applications. While it has demonstrated a certain level of strength in improving soil strength, it still struggles to fully meet the demands of certain special engineering scenarios with extremely high load-bearing capacity. This inability to effectively withstand long-term, complex loads can potentially lead to safety hazards such as deformation or even damage to engineering structures. While fluidized soil has a lower environmental impact than traditional soil reinforcement materials, with increasingly stringent environmental protection requirements, further efforts are needed to mitigate its potential environmental impact during production, construction, and use.

[0004] Against the backdrop of low-carbon, environmental protection and green building concepts becoming increasingly popular and receiving increasing attention, how to minimize the impact of fluidized solidified soil on the environment while meeting the engineering requirements for mechanical properties and fluidity has become one of the urgent and key technical challenges. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a solidifying liquid for fluidized solidified soil. By using 18-crown-6 (ECS), sodium silicate and sodium hypochlorite to prepare a new solidifying liquid, the problems of unstable solidifying effect and poor environmental protection of traditional solidifying liquids are solved, the solidifying effect and mechanical properties of fluidized solidified soil are improved, and environmental pollution is reduced.

[0006] In order to achieve the above object, the present invention provides a method for preparing a solidifying liquid for fluidized solidified soil, the method comprising:

[0007] Step 1: 18-crown-6 and sodium silicate undergo coordination reaction in water to obtain a complex solution;

[0008] Step 2, slowly adding sodium hypochlorite to the complex solution and adjusting the pH value to alkaline to obtain an alkaline solution;

[0009] Step 3: heating and stirring the alkaline solution, and obtaining a solidifying liquid for fluidized solidified soil after cooling.

[0010] Optionally, in step 1, the molar ratio of 18-crown-6 to sodium silicate is 1:(2.16-7.22).

[0011] Optionally, in step 2, the pH value is 10-12.

[0012] Optionally, in step 3, the heating temperature is 60° C.-80° C., and the heating time is 1 h-2 h.

[0013] Optionally, the mass fraction of the 18-crown-6 in the solidifying liquid for fluidized soil solidification is 5%-15%.

[0014] Optionally, the mass fraction of the sodium silicate in the solidifying liquid for fluidized soil solidification is 10%-20%.

[0015] Optionally, the mass fraction of the sodium hypochlorite in the solidifying liquid for fluidized soil solidification is 4%-6%.

[0016] Optionally, the mass fraction of water in the solidifying liquid for fluidized soil solidification is 65%-70%.

[0017] The present invention also provides a solidifying liquid for fluidized solidified soil obtained by the above-mentioned preparation method.

[0018] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0019] 1) The crown ether compound 18-crown-6 (ECS) is coordinated with sodium silicate in water to form a complex solution (the lone pairs of electrons provided by the oxygen atoms of ECS form coordination bonds with the empty orbitals provided by the sodium ions of the sodium silicate). Sodium hypochlorite is slowly added to the complex solution and the pH is adjusted to alkaline to obtain an alkaline solution. The alkaline solution is heated and stirred to ensure complete dissolution and reaction. Because the strong oxidizing property of sodium hypochlorite may oxidize the ether bonds or aromatic ring structures of ECS, reducing ECS ​​activity, ECS is first coordinated with sodium silicate to avoid reducing ECS ​​activity. The initial coordination of ECS with sodium silicate reduces the concentration of free sodium ions, lowers the solution's ionic strength, inhibits premature gelation of silicate ions caused by high ionic strength, and promotes a more even distribution of silicate ions in the solution, providing a uniform environment for the subsequent condensation reaction. In alkaline solution, silicate ions hydrolyze to form hydroxylated silicon tetrahedra (hydroxyl groups are covalently bonded to silicon atoms). These hydroxylated silicon tetrahedra undergo a dehydroxylation condensation reaction to form a stable three-dimensional network structure with excellent mechanical properties. This three-dimensional network encapsulates and fixes soil particles, enhancing their cohesion. Furthermore, in alkaline environments, ECS can more efficiently coordinate with metal ions, forming stable complexes with high-valent metal ions (calcium, magnesium, etc.) in the soil, connecting soil particles and enhancing their cohesion and strength through chemical reactions. The synergistic effect of ECS, sodium silicate, and sodium hypochlorite enhances the curing effect and mechanical properties of the fluidized solidified soil.

[0020] 2) The use of ECS, sodium silicate and sodium hypochlorite to prepare the solidifying liquid can reduce environmental pollution, has good environmental protection properties, and helps to achieve low-carbon buildings and environmental protection projects.

[0021] 3) The preparation method of the present invention is simple to operate, low in cost, and suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a flow chart of a method for preparing a solidifying liquid for fluidized solidified soil.

[0023] Figure 2 This is a comparison chart of the unconfined compressive strength test of the fluidized solidified soil prepared in Examples 1-4 of the present invention.

[0024] Figure 3 This is a comparison chart of the fluidity test of the fluidized solidified soil prepared in Examples 1-4 of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical connections; direct connections or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0028] As described in the background technology, fluidized soil, as a new type of soil reinforcement material, has a certain strength. However, in some special engineering scenarios with extremely high load-bearing capacity requirements, the strength of existing fluidized soil is still difficult to fully meet the requirements, and it still has certain pollution to the environment. Researchers have found that introducing crown ether compounds into the solidifying liquid used for fluidized soil can not only improve the performance of fluidized soil but also reduce environmental pollution. However, existing research on the application of crown ether compounds in fluidized soil is still in its infancy, and related research results are relatively few.

[0029] In order to further study the application of crown ether compounds in fluidized solidified soil, the present invention provides a method for preparing a solidifying liquid for fluidized solidified soil, the process of which is as follows: Figure 1As shown, 18-crown-6 and sodium silicate are first subjected to a coordination reaction in water to obtain a complex solution, and then sodium hypochlorite is slowly added to the complex solution and the pH value is adjusted to alkaline to obtain an alkaline solution. Finally, the alkaline solution is heated and stirred, and after cooling to room temperature, a solidifying liquid for fluidized solidified soil is obtained. The synergistic effect of 18-crown-6, sodium silicate and sodium hypochlorite not only improves the solidification effect and mechanical properties of the fluidized solidified soil, but also greatly reduces environmental pollution and has good environmental protection. Specifically, the present invention provides a method for preparing a solidifying liquid for fluidized solidified soil, which comprises:

[0030] In step 1, 18-crown-6 and sodium silicate undergo coordination reaction in water to obtain a complex solution.

[0031] 18-crown-6 and sodium silicate are stirred and dissolved in an appropriate amount of water. 18-crown-6 is a macrocyclic polyether compound with multiple oxygen atoms in its molecular structure. The oxygen atoms have lone pairs of electrons. When it undergoes a coordination reaction with sodium silicate, the oxygen atoms of 18-crown-6 donate their lone pairs of electrons to the empty orbitals of the sodium ions to form coordination bonds, encapsulating the sodium ions in the macrocyclic structure, thereby forming a stable complex solution. In some embodiments, the molar ratio of 18-crown-6 to sodium silicate is 1:(2.16-7.22). In addition, the flexible ring structure of 18-crown-6 can disperse stress through intermolecular forces, delay crack propagation, and improve toughness.

[0032] Step 2: slowly adding sodium hypochlorite to the complex solution and adjusting the pH value to alkaline to obtain an alkaline solution.

[0033] After the complex solution is prepared, an appropriate amount of sodium hypochlorite is slowly added thereto and the pH value is adjusted to alkaline.

[0034] In some embodiments, the pH is 10-12. At higher pH values, sodium silicate dissolves more readily, while at lower pH values, sodium silicate may precipitate, thereby affecting the uniformity and performance of the solidifying solution. Adjusting the pH value ensures that the reaction proceeds under optimal conditions, avoiding overly rapid or slow reactions, thereby ensuring the stability and effectiveness of the solidifying solution.

[0035] In this example, because the strong oxidizing property of sodium hypochlorite could oxidize the ether bonds or aromatic ring structures of 18-crown-6, reducing its activity, ECS was first coordinated with sodium silicate to prevent the reduction of 18-crown-6 activity. The initial coordination of ECS with sodium silicate reduces the concentration of free sodium ions, lowers the ionic strength of the solution, inhibits premature gelation of silicate ions caused by high ionic strength, and promotes a more uniform distribution of silicate ions in the solution, providing a uniform environment for subsequent condensation reactions. After adding sodium hypochlorite and adjusting the pH to alkaline, the silicate ions hydrolyze in the alkaline solution to form hydroxylated silicon-oxygen tetrahedra (hydroxyl groups are covalently bonded to silicon atoms). These hydroxylated silicon-oxygen tetrahedra undergo dehydroxylation and condensation reactions, forming a stable three-dimensional network structure with excellent mechanical properties. This three-dimensional network structure encapsulates and secures soil particles, enhancing the cohesion between soil particles. On the other hand, in an alkaline environment, 18-crown-6 can more efficiently react with metal ions, showing high activity. When mixed with soil, due to its stronger binding ability for high-valent ions, 18-crown-6 that has coordinated sodium ions will release some sodium ions through dynamic equilibrium, and in turn form more stable complexes with high-valent metal ions (calcium ions, magnesium ions, etc.) in the soil. This acts as a "bridge" between soil particles, connecting them and enhancing the cohesion and strength of soil particles through chemical reactions. Therefore, the synergistic effect of 18-crown-6, sodium silicate, and sodium hypochlorite improves the curing effect and mechanical properties of fluidized solidified soil and reduces environmental pollution.

[0036] Step 3: heating and stirring the alkaline solution, and obtaining a solidifying liquid for fluidized solidified soil after cooling.

[0037] After the alkaline solution is prepared, it is heated and stirred to achieve complete dissolution and reaction, and then cooled to room temperature to obtain a solidifying liquid for fluidized solidified soil.

[0038] In some embodiments, the heating temperature is 60°C-80°C, and the heating time is 1-2 hours. Increasing the temperature helps increase the solubility of 18-crown-6 and sodium silicate, speeding up the reaction rate and ensuring completeness of the reaction. However, the temperature should not be too high, as this may result in low viscosity and even affect the stability of the solidified soil. It should also not be too low, as this may result in insufficient strength of the solidified liquid or incomplete reaction. Therefore, the temperature should be controlled within an appropriate range to ensure that the final solidified liquid achieves the desired properties.

[0039] Because the proportions of different components in the solidifying fluid significantly affect the performance of fluidized soil, the ratios of the different components in the solidifying fluid can be flexibly adjusted according to different engineering requirements. As an example, in some embodiments, the mass fraction of 18-crown-6 in the solidifying fluid for fluidized soil is 5%-15%, the mass fraction of sodium silicate in the solidifying fluid for fluidized soil is 10%-20%, the mass fraction of sodium hypochlorite in the solidifying fluid for fluidized soil is 4%-6%, and the mass fraction of water in the solidifying fluid for fluidized soil is 65%-70%.

[0040] After step 3, the prepared solidifying liquid and fluidized solidified soil are uniformly mixed in a specific ratio. The mixed fluidized solidified soil is poured into a mold to prepare an unconfined compressive test block. After demolding, the block is wrapped with plastic wrap and cured in a standard curing room to achieve the designed strength. The standard curing room temperature is 18°C-22°C and the relative humidity is ≥95%. After curing, the unconfined compressive strength and fluidity of the prepared fluidized solidified soil are measured.

[0041] The 18-crown-6, sodium silicate and sodium hypochlorite in the following Examples 1-4 were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The chemical formula of 18-crown-6 is C 12 H 24 O6, CAS number is 17455-13-9.

[0042] Example 1

[0043] Dissolve 10g of 18-crown-6 and 15g of sodium silicate in 70g of water to obtain a complex solution. Slowly add 5g of sodium hypochlorite to the complex solution and adjust the pH value to 10.5 to obtain an alkaline solution. Heat and stir the alkaline solution at 60°C for 1 hour to ensure sufficient reaction. Cool to room temperature to obtain a solidified liquid. Evenly mix 10g of the solidified liquid with 70g of fluidized solidified soil. Pour the mixed fluidized solidified soil into a mold to prepare an unconfined compressive test block. After demoulding, wrap it with plastic wrap and place it in a standard curing room for curing. After curing, measure its performance. Figure 2-Figure 3 As shown, the unconfined compressive strength of the fluidized solidified soil is 2.5 MPa and the fluidity is 190 mm.

[0044] Example 2

[0045] 8g of 18-crown-6 and 18g of sodium silicate were stirred and dissolved in 70g of water to obtain a complex solution. 4g of sodium hypochlorite was slowly added to the complex solution and the pH value was adjusted to 11 to obtain an alkaline solution. The alkaline solution was heated and stirred at 70°C for 1 hour to ensure sufficient reaction. After cooling to room temperature, a solidified liquid was obtained. 10g of the solidified liquid was evenly mixed with 70g of fluidized solidified soil. The mixed fluidized solidified soil was poured into a mold to prepare an unconfined compressive test block. After demoulding, it was wrapped with plastic wrap and cured in a standard curing room. After the curing was completed, its performance was measured. Figure 2-Figure 3 As shown in the figure, the unconfined compressive strength of the fluidized solidified soil is 1.8 MPa and the fluidity is 180 mm.

[0046] Example 3

[0047] Dissolve 12g of 18-crown-6 and 12g of sodium silicate in 70g of water to obtain a complex solution. Slowly add 6g of sodium hypochlorite to the complex solution and adjust the pH value to 10 to obtain an alkaline solution. Heat and stir the alkaline solution at 75°C for 1 hour to ensure sufficient reaction. Cool to room temperature to obtain a solidified liquid. Evenly mix 10g of the solidified liquid with 70g of fluidized solidified soil. Pour the mixed fluidized solidified soil into a mold to prepare an unconfined compressive test block. After demoulding, wrap it with plastic wrap and cure it in a standard curing room. After curing, measure its performance. Figure 2-Figure 3 As shown in the figure, the unconfined compressive strength of the fluidized solidified soil is 3 MPa and the fluidity is 200 mm.

[0048] Example 4

[0049] 6g of 18-crown-6 and 20g of sodium silicate were stirred and dissolved in 68g of water to obtain a complex solution. 6g of sodium hypochlorite was slowly added to the complex solution and the pH value was adjusted to 11.2 to obtain an alkaline solution. The alkaline solution was heated and stirred at 80°C for 1 hour to ensure sufficient reaction. After cooling to room temperature, a solidified liquid was obtained. 10g of the solidified liquid was evenly mixed with 70g of fluidized solidified soil. The mixed fluidized solidified soil was poured into a mold to prepare an unconfined compressive test block. After demoulding, it was wrapped with plastic wrap and cured in a standard curing room. After the curing was completed, its performance was measured. Figure 2-Figure 3 As shown, the unconfined compressive strength of the fluidized solidified soil is 1.5 MPa and the fluidity is 175 mm.

[0050] It can be seen from the above test results that in Example 1 and Example 3, the content of 18-crown-6 is relatively high, and it forms more and more stable complexes with the metal ions in the soil. The fluidized solidified soil exhibits higher unconfined compressive strength and fluidity, and is suitable for projects requiring high strength and high stability. In Example 2 and Example 4, the content of 18-crown-6 is relatively low, and it forms fewer complexes with the metal ions in the soil. Although the fluidized solidified soil exhibits lower unconfined compressive strength and fluidity, it can still meet general engineering needs and has cost advantages. Therefore, according to different engineering requirements, the ratio of different components in the solidifying liquid can be flexibly adjusted to achieve the best solidification effect and economic benefits.

[0051] In summary, the present invention involves a coordination reaction between 18-crown-6 and sodium silicate in water to form a complex solution (the lone pairs of electrons provided by the oxygen atoms in the ECS form coordination bonds with the empty orbitals provided by the sodium ions in the sodium silicate). Sodium hypochlorite is then slowly added to the complex solution and the pH is adjusted to alkaline to obtain an alkaline solution. The alkaline solution is then heated and stirred to ensure sufficient dissolution and reaction. Because the strong oxidizing properties of sodium hypochlorite can oxidize the ether bonds or aromatic ring structures of the ECS, reducing its activity, the ECS is first coordinated with sodium silicate to avoid a decrease in ECS activity. The initial coordination of the ECS with sodium silicate reduces the concentration of free sodium ions, lowers the solution's ionic strength, inhibits premature gelation of silicate ions caused by high ionic strength, and helps the silicate ions become more evenly distributed in the solution, providing a uniform environment for the subsequent condensation reaction. In an alkaline solution, silicate ions hydrolyze to form hydroxylated silicon tetrahedra, which then undergo a dehydroxylation condensation reaction to form a stable three-dimensional network structure with excellent mechanical properties. This three-dimensional network encapsulates and fixes soil particles, enhancing their cohesion. Furthermore, in an alkaline environment, ECS can more efficiently coordinate with metal ions, forming stable complexes with high-valent metal ions (such as calcium and magnesium) in the soil, connecting soil particles and enhancing their cohesion and strength through chemical reactions. The synergistic effect of ECS, sodium silicate, and sodium hypochlorite enhances the curing effect and mechanical properties of the fluidized solidified soil. Furthermore, preparing this solidifying solution reduces environmental pollution, and the preparation method is simple and inexpensive, making it suitable for large-scale application.

[0052] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing a solidifying liquid for fluidized solidified soil, characterized in that: The method includes: Step 1: 18-crown-6 and sodium silicate undergo coordination reaction in water to obtain a complex solution; Step 2, slowly adding sodium hypochlorite to the complex solution and adjusting the pH value to alkaline to obtain an alkaline solution; Step 3: heating and stirring the alkaline solution, and obtaining a solidifying liquid for fluidized solidified soil after cooling.

2. The method for preparing a solidifying liquid for fluidized solidified soil according to claim 1, wherein: In the step 1, the molar ratio of 18-crown-6 to sodium silicate is 1:(2.16-7.22).

3. The method for preparing a solidifying liquid for fluidized solidified soil according to claim 1, wherein: In the step 2, the pH value is 10-12.

4. The method for preparing a solidifying liquid for fluidized solidified soil according to claim 1, wherein: In step 3, the heating temperature is 60° C.-80° C., and the heating time is 1 h-2 h.

5. The method for preparing a solidifying liquid for fluidized solidified soil according to claim 1, wherein: The mass fraction of the 18-crown-6 in the solidifying liquid for fluidized soil solidification is 5%-15%.

6. The method for preparing a solidifying liquid for fluidized solidified soil according to claim 1, wherein: The mass fraction of the sodium silicate in the solidifying liquid for fluidized soil solidification is 10%-20%.

7. The method for preparing a solidifying liquid for fluidized solidified soil according to claim 1, wherein: The mass fraction of the sodium hypochlorite in the solidifying liquid for fluidized soil solidification is 4%-6%.

8. The method for preparing a solidifying liquid for fluidized solidified soil according to claim 1, wherein: The mass fraction of water in the solidifying liquid for fluidized soil solidification is 65%-70%.

9. A solidifying liquid for fluidized solidified soil obtained by the preparation method according to claims 1 to 8.

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