Preparation method and application of fly ash-based soft soil curing agent

Abstract

The invention provides a preparation method and application of a fly ash-based soft soil curing agent, and aims to improve the activity and strength of the curing agent by using fly ash, lime, gypsum, silica fume and the like as main raw materials and adding a reinforcing agent such as metakaolin and nano-silica and an exciting agent such as sodium hydroxide and sodium carbonate. The method comprises the following steps: pretreating the raw materials, mixing according to a ratio, carrying out hydration reaction at a proper water-cement ratio, compacting and molding, and curing under the control of temperature and humidity. And crushing and sieving the cured curing agent to obtain a finished product. The curing agent shows excellent compressive strength, shear strength and water resistance, and is suitable for reinforcement of high-water-content soft soil. According to the invention, the material cost is reduced, the environmental influence is reduced, and the application prospect is wide.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, in particular to a preparation method of a fly ash-based soft soil solidifying agent and application thereof. Background Art

[0002] In engineering construction, soft soil, due to its special physical and mechanical properties, often poses a huge challenge to the stability and safety of buildings. Soft soil usually has the characteristics of high water content, low strength, high compressibility and low permeability, which makes it easy to settle and shear when bearing loads, leading to engineering accidents such as foundation instability, building tilt or collapse. Therefore, how to effectively enhance the strength and stability of soft soil foundation is an important research topic in the field of civil engineering.

[0003] At present, the solidification treatment of soft soil mainly relies on traditional solidifying agents, such as cement, lime, etc. These solidifying agents react with the water and other chemical components in the soft soil to generate a series of hydration products with cementing effect, thereby improving the strength and stability of the soft soil. However, these traditional solidifying agents have some significant limitations in practical applications:

[0004] Environmental impact: The production process of cement and lime is energy-intensive and accompanied by large amounts of carbon dioxide emissions, which have an adverse impact on the environment. In addition, these materials may cause soil alkalinization during use, which has a further negative impact on the ecological environment.

[0005] Cost issue: The raw material cost of cement and lime is relatively high, especially in large-scale projects. The use of these curing agents will significantly increase the project cost, which is not conducive to the goals of economy and sustainable development.

[0006] Unsatisfactory curing effect: Under some special geological conditions, such as soft soil with high water content or soil containing organic matter, the effect of traditional curing agents is poor and it is difficult to achieve an ideal curing effect. In some projects, even if a large amount of curing agents are invested, the mechanical properties of the soil are difficult to meet the design requirements.

[0007] Fly ash is an industrial waste produced by coal-fired power plants. It contains a large amount of active silicon oxide and aluminum oxide. These components can participate in hydration reactions under the action of appropriate activators to generate substances with cementing properties. Therefore, using fly ash as the main raw material to prepare soft soil solidifying agent can not only effectively utilize industrial waste and reduce environmental pollution, but also significantly reduce engineering costs.

[0008] Fly ash-based solidifying agents can effectively stimulate the activity of fly ash by combining appropriate reinforcing agents and activators, such as metakaolin, nano-silicon dioxide, sodium hydroxide, etc., so that it reacts with water and other components in soft soil to generate a large amount of hydration products, such as hydrated calcium silicate (C-S-H) and ettringite, etc. These products can significantly improve the compressive strength and shear strength of soft soil foundations and enhance the stability of the foundation.

[0009] Therefore, we urgently need to design a preparation method and application of a fly ash-based soft soil solidifying agent to solve these problems. Summary of the invention

[0010] The purpose of the present invention is to provide a method for preparing a fly ash-based soft soil solidifying agent and its application in view of the deficiencies of the prior art, so as to solve the problems raised in the background technology.

[0011] To achieve the above object, the present invention provides the following technical solution: a method for preparing a fly ash-based soft soil solidifying agent, the method comprising the following steps:

[0012] Raw material selection: fly ash, lime, gypsum, silica fume, enhancer and activator are selected as the main raw materials, among which:

[0013] The mass percentage of fly ash is 40%-60%,

[0014] The mass percentage of lime is 15%-25%,

[0015] The mass percentage of gypsum is 10%-20%,

[0016] The mass percentage of silica fume is 5%-10%,

[0017] The mass percentage of the enhancer is 2%-8%,

[0018] The mass percentage of the stimulant is 1%-5%;

[0019] Raw material pretreatment: Dry the fly ash to remove excess moisture, and crush the lime, gypsum, silica fume, enhancer and activator separately and pass them through a 100-mesh sieve to ensure the uniformity of the raw material particles.

[0020] Selection of reinforcing agent: reinforcing agents include but are not limited to: metakaolin, aluminum phosphate, aluminosilicate, nano-silica, among which the use of metakaolin can improve the compressive strength and shear strength of the curing agent.

[0021] Selection of activator: Activators include but are not limited to sodium carbonate, sodium hydroxide, potassium hydroxide, and sodium sulfate. The use of sodium hydroxide can significantly accelerate the activation reaction of fly ash and improve the curing effect.

[0022] Raw material mixing: evenly mix the treated fly ash, lime, gypsum, silica fume, enhancer and activator according to the SI ratio, and use mechanical stirring equipment to continuously stir for 15-30 minutes at room temperature to ensure that all ingredients are evenly mixed.

[0023] Hydration reaction: Add water (water-cement ratio 0.4-0.6) to the mixture and continue stirring for 5-15 minutes, then let it stand for 24-48 hours to promote the initial hydration reaction and ensure the full reaction of each component in the mixture.

[0024] Molding and curing: The mixed material after the hydration reaction is pressed into shape, placed in a mold, and cured for 7-28 days at a temperature of 20-30°C and a relative humidity of more than 90%. During the curing period, it is kept moist to promote the improvement of the strength of the curing agent.

[0025] Crushing and screening: The cured solidifying agent lumps are crushed and screened through a 200-mesh sieve to ensure uniform particle size of the finished product, thus obtaining the final fly ash-based soft soil solidifying agent product.

[0026] As a preferred technical solution of the present invention, the reinforcing agent is kaolin with a mass percentage of 5%-8%. The kaolin as a reinforcing agent can undergo a secondary reaction with the active silicon oxide and aluminum oxide in the fly ash to form more hydration products such as ettringite, thereby significantly improving the compressive strength and shear strength of the curing agent.

[0027] As a preferred technical solution of the present invention, the activator is sodium hydroxide, and its mass percentage is 2%-5%. Sodium hydroxide within this ratio range can effectively activate the vitreous component in fly ash, promote its reaction rate with water and other compounds, form more calcium silicate hydrate (CSH) gel, and improve the initial and long-term strength of the curing agent.

[0028] As a preferred technical solution of the present invention, the water-cement ratio is preferably 0.5, and the step of adding water includes adding water twice, stirring after adding 50%-60% of the water for the first time, and then adding the remaining water, and continuing to stir for 5-10 minutes to ensure that all raw material particles are evenly moistened and fully reacted to avoid local drying or over-wetting.

[0029] As a preferred technical solution of the present invention, during the curing process, the humidity in the curing environment is maintained above 90% by covering with a wet cloth or by timed spraying. The frequency of the timed spraying is once every 12 hours, and the amount of each spray is controlled at 0.1-0.3L / m2 to prevent uneven curing caused by rapid evaporation of surface moisture.

[0030] As a preferred technical solution of the present invention, the molded material can be cured by steam or in a closed manner. The steam curing temperature is controlled at 60°C-80°C for 4-6 hours, which can accelerate the hydration reaction inside the curing agent and further improve its early strength. During the closed curing process, the curing agent is covered with a sealed bag or plastic film to maintain its humidity, thereby reducing water loss during the curing process.

[0031] As a preferred technical solution of the present invention, the main chemical components of the fly ash include 45%-55% silicon dioxide, 20%-30% aluminum oxide, and 5%-15% calcium oxide, and the selected fly ash is primary or secondary fly ash, among which fly ash with higher silicon dioxide and aluminum oxide content can better participate in the activation reaction and improve the compressive strength and durability of the final curing agent.

[0032] As a preferred technical solution of the present invention, the fineness of the finished curing agent particles is preferably controlled to be above 200 meshes, and the particle diameter range is below 0.074 mm, so as to ensure the uniform distribution of the curing agent in the soft soil, improve its permeability and stability in the soft soil matrix, reduce the amount of materials used and optimize the construction performance.

[0033] As a preferred technical solution of the present invention, the drying temperature of the fly ash is controlled between 105°C and 120°C to remove free moisture, but not exceeding 120°C to avoid high temperature treatment causing changes in the glass structure in the fly ash and affecting its activity, thereby ensuring the effectiveness of subsequent reactions.

[0034] The invention provides a method for preparing a fly ash-based soft soil solidifying agent. The prepared solidifying agent is used for treating soft soil base.

[0035] A method for treating a soft soil foundation using a fly ash-based soft soil curing agent comprises the following steps:

[0036] The prepared curing agent product is evenly spread on the surface of the soft soil or directly mixed into the soft soil, and mixed by mechanical stirring or compacting equipment to make the curing agent fully contact with the soft soil;

[0037] Maintain proper humidity in the mixed soft soil, the humidity should be controlled between 15%-25%;

[0038] Carry out curing for 7-28 days, and keep the mixed soil moist during the curing period to ensure that the hydration reaction of the curing agent can continue and achieve the optimal strength.

[0039] Compared with the prior art, the present invention has the following beneficial effects: the present invention proposes a method for preparing a soft soil solidifying agent based on fly ash, and improves and optimizes the deficiencies in the prior art. By introducing different types of reinforcing agents and activators, the fly ash-based solidifying agent of the present invention greatly improves the solidification effect while maintaining environmental protection and economy, especially in terms of early strength development and durability.

[0040] Compared with traditional curing agents, the present invention has the following innovations and practicalities:

[0041] Environmental friendliness of materials: Using industrial waste fly ash as the main raw material reduces environmental pollution and achieves effective recycling of resources.

[0042] Cost advantage: Fly ash has low cost and simple preparation process, which can significantly reduce engineering costs and has broad prospects for promotion and application.

[0043] Excellent curing effect: Through the reasonable proportion of the reinforcing agent and the activator, the curing agent of the present invention can significantly improve the compressive strength, shear strength and water resistance of soft soil, and is particularly suitable for the treatment of soft soil with high water content or under complex geological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The present invention provides a flowchart of a method for preparing a fly ash-based soft soil solidifying agent. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings and multiple embodiments.

[0047] Example 1: Preparation of fly ash-based soft soil solidifying agent reinforced with metakaolin

[0048] Raw material proportioning and processing

[0049] Main ingredients:

[0050] Fly ash: 50%

[0051] Lime: 20%

[0052] Gypsum: 15%

[0053] Silica fume: 10%

[0054] Metakaolin (reinforcement agent): 3%

[0055] Sodium hydroxide (activator): 2%

[0056] Step 1: Raw material pretreatment

[0057] Drying of fly ash: Place the fly ash in an oven and dry it at 110°C for 2 hours. This step is to remove free moisture from the fly ash to avoid excessive moisture content in the subsequent mixing process, resulting in an overly wet or uneven mixture. The dried fly ash should be cooled to room temperature to prevent the high temperature from affecting the mixing effect of other raw materials.

[0058] Treatment of other raw materials: Lime, gypsum and silica fume are crushed separately to make their particle size less than 100 mesh. Metakaolin and sodium hydroxide also need to be crushed and sieved to ensure that the particle size of each component is uniform. These processing steps can ensure that the components are fully contacted during the mixing process, enhancing the uniformity and efficiency of the reaction.

[0059] Step 2: Mix the ingredients

[0060] Dry mixing: Mix the dried fly ash with other pre-treated raw materials in proportion. Use a high-speed mechanical stirrer to stir for 20 minutes at room temperature. The key to this process is to ensure the uniform distribution of the raw materials, especially the metakaolin and sodium hydroxide, which play a key role in the hydration reaction.

[0061] Step 3: Hydration reaction

[0062] Add water: Add water at a water-cement ratio of 0.5, using the step-by-step method, first add 60% of the total water, stir for 5 minutes, then add the remaining 40%, and continue stirring for 5 minutes. By adding water in stages, you can prevent the mixture from being too viscous or lacking in water, and ensure that the water is evenly distributed throughout the mixture.

[0063] Standing reaction: The stirred mixture is allowed to stand for 48 hours. During this process, the active silicon oxide in the fly ash reacts chemically with sodium hydroxide to form hydrated calcium silicate (C-S-H) gel, which is a key step in improving the strength of the material. The standing time can be adjusted appropriately according to the ambient temperature to ensure the adequacy of the reaction.

[0064] Step 4: Forming and curing

[0065] Compacting: Pour the mixture after hydration into a mold and compact it using a hydraulic press. The compacting process can reduce the void ratio in the mixture, increase the density of the final curing agent, and thus improve its mechanical properties.

[0066] Curing conditions: Place the formed curing agent block in a constant temperature room at 25℃ and control the relative humidity to above 90%. Spray water mist on the curing agent surface every 12 hours to maintain humidity and prevent the surface from drying out. The curing time is 14 days, which helps further hydration and strength growth of the curing agent.

[0067] Step 5: Crushing and sieving

[0068] Crushing: After curing, the curing agent blocks are crushed by a mechanical crusher to break them into smaller particles for subsequent application.

[0069] Screening: Use a 200-mesh screen to screen the crushed curing agent to ensure that the finished product has uniform particle size. Fine particles can be better distributed evenly in the soft soil and improve the curing effect.

[0070] Performance Testing

[0071] The compressive strength of the soft soil foundation treated with the curing agent reached 2.5MPa and the shear strength reached 0.8MPa. After 7 days of curing, the compressive strength increased by 35%, indicating that the formula has good reinforcement effect and fast hardening characteristics. For detailed data, please refer to Table 1.

[0072] Example 2: Preparation of fly ash-based soft soil solidifying agent reinforced by aluminosilicate

[0073] Raw material proportioning and processing

[0074] Main ingredients:

[0075] Fly ash: 45%

[0076] Lime: 25%

[0077] Gypsum: 15%

[0078] Silica fume: 8%

[0079] Aluminosilicate (reinforcement agent): 5%

[0080] Sodium carbonate (activator): 2%

[0081] Step 1: Raw material pretreatment

[0082] Treatment of fly ash: Dry at 105℃ for 1.5 hours to remove free moisture in the fly ash. After treatment, the fly ash should be allowed to cool to room temperature before use.

[0083] Treatment of other raw materials: lime, gypsum, silica fume, aluminum silicate and sodium carbonate are crushed to less than 100 meshes respectively to ensure uniform particle size. The pretreatment of these raw materials ensures full contact of each component during mixing and enhances the hydration reaction effect.

[0084] Step 2: Mix the ingredients

[0085] Dry mixing: Mix all the raw materials in proportion and stir at medium speed in a mechanical stirrer for 15 minutes. Make sure that the aluminosilicate is in full contact with the fly ash, because the aluminosilicate can react with sodium carbonate during the hydration process to form ettringite with higher strength, thereby enhancing the strength of the curing agent.

[0086] Step 3: Hydration reaction

[0087] Add water in steps: add 60% of the water first according to the water-cement ratio of 0.45, stir for 5 minutes, add the remaining 40% of the water, and continue stirring for 5 minutes. This operation helps to avoid separation of the mixture and ensure that all solid particles are evenly wetted.

[0088] Standing reaction: Let the evenly stirred mixture stand for 24 hours to allow the sodium carbonate to fully react with the fly ash and aluminosilicate to generate hydration products.

[0089] Step 4: Steam curing and molding

[0090] Molding: Pour the hydrated mixture into a mold and compact it into shape, then steam cure it in a 70°C steam environment for 4 hours. Steam curing can accelerate the hydration reaction and improve the early strength.

[0091] Closed curing: After steam curing, place the sample in a closed environment for a further 7 days to prevent moisture loss and premature drying of the curing agent.

[0092] Step 5: Crushing and sieving

[0093] Crushing and screening: The cured curing agent lumps are crushed by a crusher and screened through a 200-mesh screen to ensure that the finished product particles are uniform in fineness.

[0094] Performance Testing

[0095] The compressive strength of this curing agent is 3.0MPa, the shear strength is 1.0MPa, and the compressive strength increases by 40% within 7 days. The combination of steam curing and closed curing significantly improves the early strength of the material, which is suitable for rapid prototyping engineering needs.

[0096] Example 3: Preparation of fly ash-based soft soil solidifying agent reinforced with nano-silicon dioxide

[0097] Raw material proportioning and processing

[0098] Main ingredients:

[0099] Fly ash: 55%

[0100] Lime: 20%

[0101] Gypsum: 10%

[0102] Silica fume: 5%

[0103] Nano-silicon dioxide (reinforcement agent): 7%

[0104] Potassium hydroxide (activator): 3%

[0105] Step 1: Raw material pretreatment

[0106] Treatment of fly ash: Dry the fly ash at 120°C for 2 hours to ensure that its moisture content is below 1%, and then cool it to room temperature for use.

[0107] Treatment of other raw materials: Grind and sieve lime, gypsum, silica fume, nano-silicon dioxide and potassium hydroxide separately to ensure that the particle size of all raw materials is uniform.

[0108] Step 2: Mix the ingredients

[0109] Dry mixing: Mix fly ash with other raw materials in proportion, stir at high speed in a mechanical stirrer for 25 minutes to ensure that nano-silicon dioxide is evenly distributed in the mixture. Nano-silicon dioxide has a very high surface area and activity, and can react with fly ash to form a high-density C-S-H gel, which improves the density and strength of the material.

[0110] Step 3: Hydration reaction

[0111] Add water: Add water at a water-cement ratio of 0.6 at one time, stir for 10 minutes to ensure that all raw materials are evenly moistened and initially reacted. Let stand for 48 hours to allow the hydration reaction to proceed fully.

[0112] Step 4: Forming and curing

[0113] Compacting and molding: Pour the hydrated mixture into the mold and compact it using a hydraulic press.

[0114] Wet curing: Place the formed curing agent in a constant temperature and humidity environment at 25°C and relative humidity above 95% for 28 days. Spray twice a day to ensure that the curing agent maintains sufficient humidity during the curing period to avoid surface cracking and shrinkage.

[0115] Step 5: Crushing and sieving

[0116] Crushing and screening: After curing, use a crusher to crush the curing agent lumps and screen the finished product through a 200-mesh screen.

[0117] Performance test: The compressive strength of the curing agent is 3.5MPa, the shear strength is 1.2MPa, and the compressive strength increases by 50% in 28 days. The material shows excellent durability in hot and humid environments, and the water absorption rate is only 12%, which is suitable for foundation reinforcement in wetlands and coastal areas.

[0118] Example 4: Preparation of fly ash-based soft soil solidifying agent reinforced with aluminum phosphate

[0119] Raw material proportioning and processing

[0120] Main ingredients:

[0121] Fly ash: 60%

[0122] Lime: 15%

[0123] Gypsum: 12%

[0124] Silica fume: 6%

[0125] Aluminum phosphate (reinforcer): 5%

[0126] Sodium sulfate (activator): 2%

[0127] Step 1: Raw material pretreatment

[0128] Treatment of fly ash: Dry at 110℃ for 1.5 hours to ensure that its moisture content drops below 1%.

[0129] Treatment of other raw materials: lime, gypsum, silica fume, aluminum phosphate and sodium sulfate are crushed to less than 100 mesh respectively.

[0130] Step 2: Mix the ingredients

[0131] Dry mixing: Mix all the raw materials in proportion and stir for 20 minutes. During the hydration process, aluminum phosphate can react with the active ingredients in fly ash to form phosphate compounds. These compounds have high chemical stability and mechanical strength, which can significantly improve the durability of the curing agent.

[0132] Step 3: Hydration reaction

[0133] Add water in steps: add water twice according to the water-cement ratio of 0.55. First add 60% of the water and stir for 10 minutes, then add the remaining water and stir for 5 minutes to ensure uniform wetting.

[0134] Standing reaction: The stirred mixture is allowed to stand for 48 hours to ensure the adequacy of the hydration reaction.

[0135] Step 4: Forming and curing

[0136] Compacting and molding: After the mixture is compacted and molded, it is cured for 21 days in an environment of 30°C and humidity above 90%. During the curing period, spray once every 8 hours to prevent the surface from drying out and cracking.

[0137] Sealed curing: After the curing is completed, place the formed curing agent block in a sealed bag and continue to seal and cure for 7 days to ensure the complete internal hydration reaction.

[0138] Step 5: Crushing and sieving

[0139] Crushing and sieving: Crushing the cured curing agent blocks and passing them through a 200-mesh sieve to obtain fine and uniform granular finished products.

[0140] Performance Testing

[0141] The compressive strength of the curing agent is 2.8MPa, the shear strength is 1.0MPa, and the compressive strength increases by 45% in 21 days. The material shows good freeze-thaw resistance. After 15 freeze-thaw cycles, the compressive strength only decreases by 10%, making it suitable for foundation reinforcement in cold regions.

[0142] Comparative example: untreated soft soil

[0143] Raw material proportioning and processing

[0144] Raw materials: natural soft clay, without any additives.

[0145] Process

[0146] No curing agent treatment: The mechanical properties of natural soft soil are tested directly without any curing agent treatment.

[0147] The following is a table of experimental data of various embodiments and comparative examples.

[0148]

[0149] Performance analysis summary:

[0150] Compressive strength: In different embodiments, the compressive strength is significantly improved by using different reinforcing agents and activators. Among them, the compressive strength of embodiment 3 is the highest, which is 3.5 MPa, and is suitable for foundation reinforcement projects with higher strength requirements.

[0151] Shear strength: The shear strength in both Example 2 and Example 3 reached or exceeded 1.0 MPa, indicating that these formulations performed well in providing lateral stability.

[0152] Curing time and compressive strength growth: In the early (7 days) and long-term (28 days, 21 days) curing stages, the curing agents in each example showed good strength growth, especially Example 3, which increased its compressive strength by 50% within 28 days.

[0153] Water absorption rate: By comparison, the water absorption rate of each embodiment is significantly lower than that of the untreated soft soil, indicating that these curing agents not only improve the strength of the soil, but also improve its water resistance and reduce the potential problems of soft soil in a humid environment.

[0154] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in the field. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a fly ash-based soft soil solidifying agent, characterized in that: The method comprises the following steps: S1: Raw material selection: fly ash, lime, gypsum, silica fume, enhancer and activator, among which: The mass percentage of fly ash is 40%-60%, The mass percentage of lime is 15%-25%, The mass percentage of gypsum is 10%-20%, The mass percentage of silica fume is 5%-10%, The mass percentage of the enhancer is 2%-8%, The mass percentage of the stimulant is 1%-5%; S2: Raw material pretreatment: Dry the fly ash to remove excess moisture, and crush the lime, gypsum, silica fume, enhancer and activator separately and pass them through a 100-mesh sieve; Selection of reinforcing agent: reinforcing agents include but are not limited to: metakaolin, aluminum phosphate, aluminosilicate or nano-silicon dioxide; Selection of stimulants: stimulants include but are not limited to: sodium carbonate, sodium hydroxide, potassium hydroxide, sodium sulfate; S3: Raw material mixing: The treated fly ash, lime, gypsum, silica fume, reinforcing agent and activator are uniformly mixed according to the proportion of S1, and stirred continuously for 15-30 minutes at room temperature using a mechanical stirring device; Hydration reaction: add water to the mixture with a water-to-cement mass ratio of 0.4-0.6, and continue stirring for 5-15 minutes, then let it stand for 24-48 hours to allow the initial hydration reaction to proceed fully; S4: Molding and curing: The mixed material after the hydration reaction is pressed into a mold, placed in a mold, and cured for 7-28 days at a temperature of 20-30°C and a relative humidity of more than 90°C, with regular spraying every day; S5: Crushing and screening: The cured solidifying agent lumps are crushed and screened through a 200-mesh sieve to ensure that the finished product particles are uniform in fineness, thereby obtaining the final fly ash-based soft soil solidifying agent product.

2. The method for preparing the fly ash-based soft soil solidifying agent according to claim 1, characterized in that: The reinforcing agent is metakaolin, which has a weight proportion of 5-8. The metakaolin as a reinforcing agent can generate more ettringite hydration products by secondary reaction with active silicon oxide and aluminum oxide in fly ash.

3. The method for preparing the fly ash-based soft soil solidifying agent according to claim 1, characterized in that: The activator is sodium hydroxide, and its mass percentage is 2%-5%.

4. The method for preparing the fly ash-based soft soil solidifying agent according to claim 1, characterized in that: The water-cement ratio is 0.5, and the step of adding water includes adding water twice, stirring after adding 50%-60% of the water for the first time, and then adding the remaining water and continuing to stir for 5-10 minutes.

5. The method for preparing the fly ash-based soft soil solidifying agent according to claim 1, characterized in that: During the molding and curing, the humidity in the curing environment is maintained above 90% by covering with a wet cloth or by timed spraying. The frequency of the timed spraying is once every 12 hours, and the amount of each spray is controlled at 0.1-0.3L / m2.

6. The method for preparing the fly ash-based soft soil solidifying agent according to claim 1, characterized in that: The fly ash-based soft soil curing agent product adopts steam curing or closed curing, the steam curing temperature is controlled at 60° C.-80° C., and the time is 4-6 hours; during the closed curing process, the curing agent is covered with a sealed bag or a plastic film.

7. The method for preparing the fly ash-based soft soil solidifying agent according to claim 1, characterized in that: The chemical composition of the fly ash includes 45%-55% of silicon dioxide, 20%-30% of aluminum oxide, and 5%-15% of calcium oxide, and the selected fly ash is primary or secondary fly ash.

8. The method for preparing the fly ash-based soft soil solidifying agent according to claim 1, characterized in that: The fineness of the finished curing agent particles is controlled to be above 200 meshes, and the particle diameter range is below 0.074 mm.

9. The method for preparing the fly ash-based soft soil solidifying agent according to claim 1, characterized in that: The drying temperature of the fly ash is controlled between 105°C and 120°C.

10. A fly ash-based soft soil solidifying agent prepared by the method for preparing a fly ash-based soft soil solidifying agent according to any one of claims 1 to 9 and applied to treating soft soil foundation.

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