Degradable soil stabilizer and preparation method thereof

Abstract

The invention relates to the technical field of soil remediation materials, in particular to a degradable soil stabilizer and a preparation method thereof. The degradable soil stabilizer provided by the invention comprises the following components: phosphate grafted graphene oxide, polylactic acid, Portland cement, fluidized bed combustion ash, a composite anti-freezing agent, a silane coupling agent and the balance of soil, the mass percent of each component is as follows: 0.5%-3% of phosphate grafted graphene oxide, 2%-5% of polylactic acid, 25%-40% of Portland cement, 10%-15% of fluidized bed combustion ash, 1%-3% of a composite anti-freezing agent and 0.3%-1% of a silane coupling agent. The degradable soil stabilizer disclosed by the invention has the effect of simultaneously improving the compressive strength and the degradability of the soil stabilizer.

Description

Technical Field

[0001] This invention relates to the technical field of soil remediation materials, and more specifically, to a biodegradable soil stabilizer and its preparation method. Background Technology

[0002] Soil stabilizers are materials that improve the engineering properties of soil through physical or chemical processes. They bind loose soil particles into a dense whole, thereby enhancing its strength, water stability, impermeability, and durability. They are widely used in roadbed reinforcement, dam seepage prevention, site hardening, desertification control, and contaminated soil stabilization.

[0003] In related technologies, the main components of soil stabilizers typically include inorganic materials such as cement and lime. However, these inorganic materials suffer from insufficient compressive strength and cannot be degraded for reuse in the field. Therefore, mechanical crushing is required during the return of soil to the field, which in turn causes serious damage to the soil structure. Summary of the Invention

[0004] The present invention aims to simultaneously improve the compressive strength and biodegradability of soil stabilizers.

[0005] To address the aforementioned problems, as a first aspect, the present invention provides a biodegradable soil stabilizer, wherein the components of the biodegradable soil stabilizer include phosphate-grafted graphene oxide and polylactic acid, wherein the structural formula of the phosphate-grafted graphene oxide is shown in Formula I: ; In Formula I, A represents graphene oxide.

[0006] Optionally, the components of the biodegradable soil stabilizer may further include silicate cement, sulfur-fixing ash, composite antifreeze agent, silane coupling agent, and the remainder soil.

[0007] Optionally, the mass percentages of each component of the biodegradable soil stabilizer are as follows: phosphate-grafted graphene oxide: 0.5% to 3%, polylactic acid: 2% to 5%, silicate cement: 25% to 40%, sulfur-fixing ash: 10% to 15%, composite antifreeze agent: 1% to 3%, silane coupling agent: 0.3% to 1%.

[0008] Optionally, the composite antifreeze is a mixture of calcium chloride and sodium polyacrylate.

[0009] Optionally, in the composite antifreeze, the mass ratio of calcium chloride to sodium polyacrylate is 5:3 to 3:1.

[0010] In a second aspect, the present invention also provides a method for preparing a biodegradable soil stabilizer, the method being used to prepare the biodegradable soil stabilizer as described above, the method comprising: Graphene oxide was reacted with a phosphate-olamine intermediate to obtain phosphate-grafted graphene oxide. The phosphate-grafted graphene oxide was mixed with silicate cement, sulfur-fixing ash, composite antifreeze agent, and silane coupling agent, and then wet granulated to obtain a curing agent intermediate product. The intermediate product of the solidifying agent is mixed with soil and then cured to obtain the biodegradable soil solidifying agent.

[0011] Optionally, the phosphate-ethanolamine intermediate is selected from any one or more of ethanolamine phosphate, diethanolamine phosphate, and triethanolamine phosphate.

[0012] Optionally, the reaction temperature of the graphene oxide with the phosphate-alcoholamine intermediate is 60 to 80°C.

[0013] Optionally, the mass ratio of the solidifying agent intermediate product to the soil during mixing is 1:8 to 1:10.

[0014] Optionally, when the intermediate product of the curing agent is mixed with soil and then cured, the curing time is 5 to 10 days.

[0015] The advantages of this invention compared to the prior art are: This invention introduces graphene oxide and polylactic acid (PLA) into a soil stabilizer. Graphene oxide, with its extremely high specific surface area and Young's modulus, can be uniformly dispersed in PLA to form physical cross-linking points. When the stabilizer material is under stress, the graphene oxide sheets effectively transfer the load, hindering the slippage of PLA molecular chains and significantly improving the strength, modulus, and toughness of the composite material. Furthermore, when phosphate groups are grafted onto the surface of graphene oxide, the negative charge of the phosphate groups further reduces the aggregation of graphene oxide sheets through electrostatic repulsion, further enhancing the dispersibility and interfacial bonding of the soil stabilizer. This achieves improved compressive strength while ensuring the biodegradability of the soil stabilizer. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation process of a biodegradable soil stabilizer in an exemplary embodiment of the present invention. Detailed Implementation

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0018] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit this application. The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the description below. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0019] The degradability and eco-friendliness of soil stabilizers have become current research trends. Improving the degradability of soil stabilizers can effectively improve the engineering properties of soil, reduce road construction costs, and enhance road quality. Polylactic acid (PLA) is a bio-based biodegradable polyester polymer, polymerized from lactic acid monomers. It has excellent biocompatibility and biodegradability. The ester bonds in its molecular structure are easily broken under the influence of water and microorganisms, eventually degrading into lactic acid, which is further metabolized into water and carbon dioxide.

[0020] However, while polylactic acid (PLA) is biodegradable, its high brittleness, poor toughness, and low thermal stability make it difficult to meet the mechanical requirements of high-load-bearing structures (such as road structures). Furthermore, PLA degrades slowly in the natural environment, and the degradation process is often accompanied by a sharp decline in mechanical properties, making it impossible to maintain stable strength throughout its service life. Adding inorganic fillers (such as glass fiber and carbon fiber) can significantly improve strength, but this compromises the biocompatibility and biodegradability of PLA, and the corresponding inorganic fillers also leave environmental residues, causing pollution.

[0021] This invention provides a biodegradable soil stabilizer, the components of which include phosphate-grafted graphene oxide and polylactic acid, wherein the structural formula of the phosphate-grafted graphene oxide is shown in Formula I: ; In Formula I, A represents graphene oxide.

[0022] It should be noted that the phosphate group (PO4) 3- The core structure of the phosphorus atom (P) is a tetrahedral configuration formed by one phosphorus atom (P) and four oxygen atoms (O). One oxygen atom is connected to the phosphorus atom via a double bond (P=O), while the other three oxygen atoms are connected via single bonds and carry a negative charge (PO).- When grafted onto graphene oxide, one of the oxygen atoms will form a covalent bond with a functional group of graphene oxide (such as a hydroxyl or carboxyl group).

[0023] In this embodiment of the invention, graphene oxide and polylactic acid (PLA) are introduced into the soil stabilizer. Graphene oxide has an extremely high specific surface area and Young's modulus, and can be uniformly dispersed in PLA to form physical cross-linking points. When the stabilizer material is subjected to stress, the graphene oxide sheets can effectively transfer the load, hindering the slippage of PLA molecular chains, and significantly improving the strength, modulus, and toughness of the composite material. Furthermore, the negative charge of the phosphate groups (PO4) - This process can further reduce the aggregation of graphene oxide sheets through electrostatic repulsion, thereby improving the dispersibility and interfacial bonding of the soil stabilizer. Simultaneously, the phosphate groups can form hydrogen bonds or generate ionic interactions with other components in the soil stabilizer (such as polylactic acid and silicate cement), further enhancing the mechanical properties of the composite material. This achieves the goal of improving the compressive strength of the soil stabilizer while ensuring its biodegradability.

[0024] In some optional embodiments, the components of the biodegradable soil stabilizer also include silicate cement, sulfur-fixing ash, composite antifreeze, silane coupling agent, and the remainder soil.

[0025] In the biodegradable soil stabilizer of this embodiment, the silane coupling agent helps improve material compatibility, the composite antifreeze agent helps further enhance the freeze resistance of the stabilizer, and the silicate cement and sulfur-fixing ash help enhance the early strength of the stabilizer and reduce costs.

[0026] In some optional embodiments, the mass percentages of the components of the biodegradable soil stabilizer are as follows: phosphate-grafted graphene oxide: 0.5% to 3%, polylactic acid: 2% to 5%, silicate cement: 25% to 40%, sulfur-fixing ash: 10% to 15%, composite antifreeze agent: 1% to 4%, silane coupling agent: 0.3% to 1%.

[0027] By adjusting the proportions of each component in a biodegradable soil stabilizer, it is possible to maximize cost reduction while meeting the requirements of biodegradability and high compressive strength.

[0028] In some optional embodiments, the composite antifreeze is a mixture of calcium chloride and sodium polyacrylate, wherein the mass ratio of calcium chloride to sodium polyacrylate is 5:3 to 3:1.

[0029] Among compound antifreeze agents, calcium chloride has the core advantages of strong freezing point reduction and rapid early strength, while sodium polyacrylate improves antifreeze durability through physical protection and structural compaction. The combination of the two is conducive to achieving freezing point control, early strength, workability optimization and long-term antifreeze.

[0030] In some optional embodiments, the silicate cement is Type I silicate cement (P·I) or Type II silicate cement (P·II). The silane coupling agent may be selected from any one or more of γ-aminopropyltriethoxysilane (KH550), γ-methacryloyloxypropyltrimethoxysilane (KH570), γ-isocyanatepropyltriethoxysilane, vinyltrimethoxysilane (A171), and phenylaminomethyltriethoxysilane. It should be noted that, in practical applications, a more suitable silane coupling agent can be selected according to different soil types.

[0031] Another embodiment of the present invention provides a method for preparing a biodegradable soil stabilizer, which is used to prepare the biodegradable soil stabilizer described above. (Refer to...) Figure 1 As shown, the preparation method includes: Step S1: Graphene oxide is reacted with a phosphate-alkanolamine intermediate to obtain phosphate-grafted graphene oxide. Specifically, the phosphate-alkanolamine intermediate is selected from any one or more of ethanolamine phosphate, diethanolamine phosphate, and triethanolamine phosphate. The reaction temperature of graphene oxide with the phosphate-alkanolamine intermediate is 60 to 80°C, and the reaction time is 2 to 4 hours.

[0032] In some optional embodiments, the hydroxyl groups (-OH) in phosphoric acid (H3PO4) undergo a condensation reaction with the hydroxyl groups (-OH) in an alkanolamine (such as ethanolamine) to generate a phosphate-alkanolamine intermediate. This phosphate-alkanolamine intermediate then further bonds with the hydroxyl groups (-OH) on the surface of graphene oxide via esterification, forming stable covalent bonds. The remaining oxygen atoms of the phosphate group exist as hydroxyl groups (-OH) or in combination with alkanolamine derivatives, for example, forming a phosphate-ethanolamine structure. This stable covalent bonding effectively improves the bonding strength between graphene oxide and the phosphate groups, further enhancing the dispersibility and interfacial adhesion of the soil stabilizer.

[0033] Step S2: Phosphate-grafted graphene oxide is mixed with silicate cement, sulfur-fixing ash, composite antifreeze agent, and silane coupling agent, and then wet-granulated to obtain a curing agent intermediate product. Specifically, the dry materials such as phosphate-grafted graphene oxide, silicate cement, sulfur-fixing ash, and polylactic acid can be ball-milled and mixed first, and then a silane coupling agent solution can be added for wet granulation.

[0034] Step S3: Mix the intermediate product of the solidifying agent with the soil and then cure it to obtain a biodegradable soil solidifying agent. Specifically, the mass ratio of the intermediate product of the solidifying agent to the soil is 1:8 to 1:10, and the curing time is 5 to 10 days.

[0035] When the biodegradable soil stabilizer prepared in the embodiments of the present invention is applied to road construction, the stabilizer slurry can be sprayed onto the roadbed and compacted to form a 5 to 10 cm thick stabilized layer. When the road is abandoned, the polylactic acid is degraded by natural precipitation or irrigation water, with a disintegration rate of ≥80% within 90 days, thereby restoring farmland cultivation conditions.

[0036] The present invention will be described in detail below through specific embodiments and comparative examples: Example 1 The biodegradable soil stabilizer in this embodiment comprises the following components by weight percentage: 1.5% phosphate-grafted graphene oxide, 35% silicate cement, 12% sulfur-fixing ash, 3% polylactic acid, 1.5% calcium chloride, 0.5% sodium polyacrylate, 0.5% silane coupling agent (KH550), and the balance being soil.

[0037] The preparation method of the above-mentioned biodegradable soil stabilizer includes: Step S1: Graphene oxide is reacted with monoethanolamine phosphate at 60°C for 4 hours to obtain phosphate-grafted graphene oxide.

[0038] Step S2: First, the dry materials such as phosphate-grafted graphene oxide, silicate cement, sulfur-fixing ash, and polylactic acid are ball-milled and mixed according to the mass ratio. Then, a silane coupling agent solution is added for wet granulation to obtain the curing agent intermediate product.

[0039] Step S3: Mix the intermediate product of the curing agent with the soil at a mass ratio of 1:8, spread the mixture, and cure it at room temperature and pressure for 7 days to obtain a biodegradable soil curing agent.

[0040] Example 2 The biodegradable soil stabilizer in this embodiment comprises the following components by weight percentage: 1.4% phosphate-grafted graphene oxide, 38% silicate cement, 15% sulfur-fixing ash, 2.5% polylactic acid, 2% calcium chloride, 1% sodium polyacrylate, 0.8% silane coupling agent (KH570), and the balance being soil.

[0041] Methods for preparing biodegradable soil stabilizers include: Step S1: Graphene oxide is reacted with diethanolamine phosphate at 80°C for 2 hours to obtain phosphate-grafted graphene oxide.

[0042] Step S2: First, the dry materials such as phosphate-grafted graphene oxide, silicate cement, sulfur-fixing ash, and polylactic acid are ball-milled and mixed according to the mass ratio. Then, a silane coupling agent solution is added for wet granulation to obtain the curing agent intermediate product.

[0043] Step S3: Mix the intermediate product of the curing agent with the soil at a mass ratio of 1:10, spread the mixture, and cure it at room temperature and pressure for 7 days to obtain a biodegradable soil curing agent.

[0044] Example 3 The difference between this embodiment and Embodiment 1 is that the biodegradable soil stabilizer in this embodiment includes the following components by mass percentage: 1.2% phosphate-grafted graphene oxide, 40% silicate cement, 10% sulfur-fixing ash, 2% polylactic acid, 2% calcium chloride, 1% sodium polyacrylate, 1% silane coupling agent (KH550), and the balance being soil.

[0045] Methods for preparing biodegradable soil stabilizers include: Step S1: Graphene oxide is reacted with triethanolamine phosphate at 80°C for 2 hours to obtain phosphate-grafted graphene oxide.

[0046] Step S2: First, the dry materials such as phosphate-grafted graphene oxide, silicate cement, sulfur-fixing ash, and polylactic acid are ball-milled and mixed according to the mass ratio. Then, a silane coupling agent solution is added for wet granulation to obtain the curing agent intermediate product.

[0047] Step S3: Mix the intermediate product of the curing agent with the soil at a mass ratio of 1:10, spread the mixture, and cure it at room temperature and pressure for 7 days to obtain a biodegradable soil curing agent.

[0048] Example 4 The difference between this embodiment and Embodiment 1 is that the biodegradable soil stabilizer in this embodiment includes the following components by mass percentage: 0.5% phosphate-grafted graphene oxide, 25% silicate cement, 10% sulfur-fixing ash, 2% polylactic acid, 0.7% calcium chloride, 0.3% sodium polyacrylate, 0.3% silane coupling agent (KH550), and the balance being soil.

[0049] Example 5 The difference between this embodiment and Embodiment 1 is that the biodegradable soil stabilizer in this embodiment includes the following components by mass percentage: 3% phosphate-grafted graphene oxide, 40% silicate cement, 15% sulfur-fixing ash, 5% polylactic acid, 1% calcium chloride, 0.6% sodium polyacrylate, 1% silane coupling agent (KH550), and the balance being soil.

[0050] Comparative Example 1 This comparative example describes the preparation of a soil stabilizer based on Chinese patent document CN 103224370 A.

[0051] Comparative Example 2 The difference between this comparative example and Example 1 is that the biodegradable soil stabilizer does not contain phosphate-grafted graphene oxide, while the other components and contents remain unchanged.

[0052] Table 1 shows the 28-day compressive strength, permeability coefficient, freeze-thaw cycle capability (-20℃ to 25℃), and degradation rate within one year of the soil stabilizers in Examples 1 to 5 and Comparative Examples 1 to 2. Table 1. Data on 28-day compressive strength, permeability coefficient, freeze-thaw cycle capability (-20℃ to 25℃), and degradation rate within one year of the soil stabilizers in Examples 1 to 5 and Comparative Examples 1 to 2.

[0053] As shown in Table 1, compared with traditional soil stabilizers, the embodiment of the present invention combines phosphate-grafted graphene oxide with biodegradable polylactic acid. The prepared soil stabilizer has a compressive strength ≥15MPa, a freeze-thaw cycle count of more than 150 times without cracking, and a degradation rate of more than 90% within one year, effectively solving the contradiction between the compressive strength of the stabilizer and ecological degradation and restoration.

[0054] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A biodegradable soil stabilizer, characterized in that, The components of the biodegradable soil stabilizer include phosphate-grafted graphene oxide and polylactic acid, wherein the structural formula of the phosphate-grafted graphene oxide is shown in Formula I: ； In Formula I, A represents graphene oxide.

2. The biodegradable soil stabilizer according to claim 1, characterized in that, The components of the biodegradable soil stabilizer also include silicate cement, sulfur-fixing ash, composite antifreeze, silane coupling agent, and the remainder soil.

3. The biodegradable soil stabilizer according to claim 2, characterized in that, The mass percentages of each component of the biodegradable soil stabilizer are as follows: phosphate-grafted graphene oxide: 0.5% to 3%, polylactic acid: 2% to 5%, silicate cement: 25% to 40%, sulfur-fixing ash: 10% to 15%, composite antifreeze agent: 1% to 3%, silane coupling agent: 0.3% to 1%.

4. The biodegradable soil stabilizer according to claim 3, characterized in that, The composite antifreeze is a mixture of calcium chloride and sodium polyacrylate.

5. The biodegradable soil stabilizer according to claim 4, characterized in that, In the composite antifreeze, the mass ratio of calcium chloride to sodium polyacrylate is 5:3 to 3:

1.

6. A method for preparing a biodegradable soil stabilizer, characterized in that, The preparation method is used to prepare the biodegradable soil stabilizer as described in any one of claims 1 to 5, and the preparation method includes: Graphene oxide was reacted with a phosphate-olamine intermediate to obtain phosphate-grafted graphene oxide. The phosphate-grafted graphene oxide was mixed with silicate cement, sulfur-fixing ash, composite antifreeze agent, and silane coupling agent, and then wet granulated to obtain a curing agent intermediate product. The intermediate product of the solidifying agent is mixed with soil and then cured to obtain the biodegradable soil solidifying agent.

7. The method for preparing the biodegradable soil stabilizer according to claim 6, characterized in that, The phosphate-alcoholic intermediate is selected from any one or more of ethanolamine phosphate, diethanolamine phosphate, and triethanolamine phosphate.

8. The method for preparing the biodegradable soil stabilizer according to claim 6, characterized in that, The reaction temperature between the graphene oxide and the phosphate-olamine intermediate is 60 to 80°C.

9. The method for preparing the biodegradable soil stabilizer according to claim 6, characterized in that, The mass ratio of the solidifying agent intermediate product to the soil is 1:8 to 1:

10.

10. The method for preparing the biodegradable soil stabilizer according to claim 6, characterized in that, When the intermediate product of the curing agent is mixed with the soil and then cured, the curing time is 5 to 10 days.

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