A method for preparing a solidifying agent adapted to the pore characteristics of soft soil

Abstract

This invention discloses a method for preparing a solidifying agent adapted to the pore characteristics of soft soil, belonging to the field of roadbed treatment technology. The method includes: mixing granulated blast furnace slag powder and lime powder, adding an aqueous solution containing polyethylene glycol and stirring, then preparing tertiary spherical particles with particle sizes of 0.1-0.2 mm, 0.2-0.3 mm, and 0.3-0.4 mm by spray granulation, and mixing them at a mass ratio of 3:4:3 to form a particle size distribution that matches the 0.1-0.5 mm pore size of soft soil. This invention achieves efficient filling of soft soil pores by the solidifying agent through precise particle size distribution design. Simultaneously, by utilizing polyethylene glycol for pore-forming and ventilation drying processes, well-connected micropores are formed within the solidifying agent, promoting the full hydration reaction. This invention makes extensive use of industrial waste, resulting in low cost, environmental friendliness, and high efficiency. The obtained solidifying agent significantly improves the density, early strength, and long-term durability of solidified soft soil, making it suitable for shallow roadbed soft soil solidification projects with high water content and large void ratio.

Description

Technical Field

[0001] This invention belongs to the field of roadbed treatment technology in road engineering, and specifically relates to a method for preparing a solidifying agent adapted to the pore characteristics of soft soil. Background Technology

[0002] In road construction, shallow subgrade soft soil has poor engineering characteristics such as high water content, large void ratio, high compressibility and low strength. It is difficult to meet the requirements of road bearing capacity and long-term stability when used directly as subgrade filler. Therefore, it is necessary to treat it with a curing agent to improve its physical and mechanical properties.

[0003] Currently, most existing soft soil stabilizers employ a "powder mixing + direct addition" preparation and application method. This method has the following core drawbacks: First, the particle size distribution of the curing agent is uniform, which has a low matching degree with the irregular pores of 0.1-0.5mm inside the soft soil. This easily leads to the problem of "large pores not being filled and small pores being over-accumulated", resulting in insufficient density of the solidified body and thus affecting the curing effect. Secondly, the raw materials of the curing agent are prone to premature reaction after the slurry is left to stand, generating ineffective cementitious products, which reduces its reactivity when mixed with soft soil. Third, although existing technologies attempt to use polyethylene glycol to create micropores in the curing agent to promote the reaction, their overall process and particle design have failed to fundamentally solve the compatibility problem with the pore structure of soft soil.

[0004] Therefore, developing a curing agent that is highly compatible with the pore characteristics of soft soil, has high reactivity, and is economical and environmentally friendly, as well as its preparation method, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned shortcomings in the existing technology, this invention aims to provide a method for preparing a curing agent adapted to the pore characteristics of soft soil, thereby solving the problems of existing curing agents having a single particle size distribution and low matching degree with the pores of soft soil, resulting in insufficient filling and insufficient compaction of the cured body.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for preparing a solidifying agent adapted to the pore characteristics of soft soil, characterized by comprising: Step 1, Raw material pretreatment: Dry and crush granulated blast furnace slag to obtain granulated blast furnace slag powder; calcine and crush lime to obtain lime powder; Step 2, Raw material mixing: Weigh 10-30 parts of granulated blast furnace slag powder and 5-7 parts of lime powder by weight, mix them evenly, then add 25% deionized water containing 2% polyethylene glycol, and continue stirring to obtain a mixed slurry; Step 3, grading granulation and drying: The mixed slurry is spray-granulated to prepare three-level spherical particles with particle sizes of 0.1-0.2 mm, 0.2-0.3 mm, and 0.3-0.4 mm. The three-level spherical particles are mixed in a mass ratio of 3:4:3 to obtain mixed particles. The mixed particles are dried at 60℃-80℃ to obtain curing agent particles. Step 4, Finished product preparation: Cool the curing agent particles to obtain the final product.

[0007] The above technical solution uses a "graded granulation" process to precisely prepare three types of near-spherical particles with different particle sizes, which are then mixed in a specific ratio (3:4:3) to form a particle size distribution that highly matches the typical pore size (0.1-0.5 mm) of soft soil. This design allows the curing agent particles, after being incorporated into the soft soil, to achieve a gradation filling effect of "large particles filling large pores, small particles filling small pores, and medium particles in the middle," greatly improving the filling efficiency and density of the curing agent in the soft soil pores. Simultaneously, the addition of an aqueous solution containing polyethylene glycol to the mixed slurry lays the foundation for the subsequent formation of micropores within the curing agent particles. Spray granulation rapidly forms particles from the mixed slurry, effectively preventing premature reaction of the raw materials under static conditions and ensuring the reactivity of the curing agent. Finally, drying at 60-80℃ removes moisture and allows the polyethylene glycol to volatilize, forming well-connected micropores within the particles. These micropores, after the solidifier is mixed with the soft soil, can serve as channels for water transport, promoting the uniformity and fullness of the hydration reaction. In summary, this solution systematically improves the solidification effect of soft soil from two levels: macroscopic pore filling and microscopic reaction promotion.

[0008] Further, in step 1, the drying temperature of the granulated blast furnace slag is 105-120℃, and the drying time is 2-3 hours; after pulverization, it is passed through a 0.075mm sieve to control its specific surface area to be 400-450m² / kg. The above technical solution optimizes the pretreatment parameters of the granulated blast furnace slag. The drying temperature of 105-120℃ can effectively remove free moisture from the slag, avoiding the influence of moisture on subsequent grinding and reaction. Grinding the slag to a specific surface area of ​​400-450m² / kg and passing it through a 0.075mm sieve ensures that the slag powder has sufficient fineness and reactivity. Within this specific surface area range, the slag particles can provide sufficient surface for the gelation reaction and form structurally stable spherical particles during the subsequent granulation process, which is the basis for achieving excellent solidification effects.

[0009] Further, in step 1, the calcination temperature of the lime is 900-1000℃, and the calcination time is 1.5-2.5h; after pulverization, it is passed through a 0.075mm sieve. The above technical solution defines the activation calcination and pulverization parameters of the lime. Calcination at 900-1000℃ can decompose the calcium carbonate in the limestone and effectively avoid the "overburning" phenomenon of lime caused by excessively high temperature, thereby obtaining highly active lime powder. Passing through a 0.075mm sieve ensures the fineness of the lime powder, allowing it to be uniformly dispersed in the solidifying agent system. After the highly active, fine lime powder is mixed with the solidifying agent and soft soil, it can quickly react with water to generate Ca(OH)2, providing a highly alkaline environment, thereby efficiently activating the potential cementitious activity of granulated blast furnace slag, promoting the formation of cementitious products such as hydrated calcium silicate, and providing key impetus for the formation of early strength of the solidified body.

[0010] Further, in step 2, the granulated blast furnace slag powder has a CaO content ≥35%, a SiO2 content ≥30%, and a specific surface area of ​​400-450 m² / kg; the lime powder has a CaO content ≥80% and an impurity content ≤5%; the sodium silicate is industrial-grade liquid sodium silicate with a modulus of 2.5-3.0. The above technical solution strictly limits the chemical composition and physical properties of the core raw materials. The CaO and SiO2 content in granulated blast furnace slag is a key indicator of its cementitious activity. Slag with a CaO content ≥35% and a SiO2 content ≥30% is considered highly active slag, capable of reacting with alkaline activators to generate a large amount of cementitious hydration products. The high CaO content (≥80%) and low impurity content of the lime powder ensure that it provides a sufficient and pure alkaline environment. Sodium silicate has a modulus (molar ratio of SiO2 to Na2O) between 2.5 and 3.0, providing both sufficient alkalinity and a suitable amount of active silicon. As an early strength agent and activator, it can significantly accelerate the hydration reaction process and improve the early strength of the cured body. The synergistic effect of these raw material parameters ensures the stability and high efficiency of the curing agent.

[0011] Further, in step 2, the uniform mixing step employs a double-helix conical mixer with a stirring speed of 100-150 r / min and a stirring time of 10-15 min. After adding 25% deionized water containing 2% polyethylene glycol, stirring continues for another 10-15 min. The above technical solution optimizes the mixing process. Using a double-helix conical mixer and controlling the speed and time ensures macroscopically uniform mixing of the granulated blast furnace slag powder and lime powder. After adding the polyethylene glycol-containing aqueous solution, stirring continues for 10-15 min, allowing the liquid to uniformly wet and coat the powder particles, forming a homogeneous slurry. This uniform mixing state is a prerequisite for obtaining uniformly sized, stable, near-spherical particles through subsequent spray granulation, thus ensuring the consistency of the final curing agent product quality.

[0012] Furthermore, in step 3, the drying time is 12 hours, with ventilation maintained during the drying process. The above technical solution optimizes the drying process. Drying at 60-80℃ for 12 hours ensures that the moisture inside the particles is fully removed, preventing particle clumping and deterioration, and also allows the polyethylene glycol (PEG) to fully volatilize during heating. Maintaining slight ventilation is crucial, as it promptly removes the volatilized PEG gas, preventing it from recondensing on the particle surface, thereby effectively forming a well-connected microporous structure inside and on the surface of the curing agent particles. These micropores not only increase the specific surface area but also provide space and channels for water penetration and the growth of hydration products during subsequent mixing with soft soil, greatly promoting the depth and breadth of the curing reaction.

[0013] Furthermore, when using the curing agent, 2-4 parts by weight of sodium silicate are added, thoroughly mixed, and then added to the soft soil using a spreader. The above technical solution defines the on-site application method of the curing agent. Using sodium silicate as an admixture, mixing it with the curing agent particles during use, rather than adding it all at once during preparation, is an innovative application model. Sodium silicate is a strongly alkaline activator; if added entirely during the curing agent preparation process, it may react slowly with slag powder and lime powder, affecting the product's storage stability. The "mix and use immediately" method maximizes the retention of the activating activity of sodium silicate. When sodium silicate is mixed with the curing agent particles into the soft soil, it rapidly dissolves and activates the cementing reaction of slag and lime, providing strong early strength to the solidified body. Simultaneously, it synergistically works with the micropores within the curing agent particles to promote rapid and complete curing of the entire system.

[0014] Compared with existing methods for preparing curing agents, the specific beneficial effects of this invention are as follows: 1. Precise particle size matching and high filling efficiency: This invention uses graded granulation technology to prepare three levels of spherical particles with particle sizes of 0.1-0.2mm, 0.2-0.3mm, and 0.3-0.4mm, which are then mixed in a 3:4:3 mass ratio to form a particle size distribution that matches the 0.1-0.5mm pore height of soft soil. This design allows the solidifier particles to tightly and uniformly fill the pores at all levels in the soft soil, significantly improving the density and interfacial bonding of the solidified body, and solving the problems of uneven filling and insufficient strength caused by the mismatch between the solidifier and the pore size of the soft soil in existing technologies.

[0015] 2. Excellent pore structure for more complete reaction: By adding polyethylene glycol to the slurry and combining it with a ventilation and drying process, well-connected micropores are formed inside the curing agent particles. These micropores act as "water absorption channels" and "reaction spaces" after the curing agent is mixed with soft soil, guiding water to penetrate evenly and providing sufficient space for hydration reactions. This promotes the formation and growth of cementitious products, significantly enhancing the strength and long-term stability of the solidified body.

[0016] 3. Highly efficient and environmentally friendly raw materials with significant cost advantages: This invention utilizes granulated blast furnace slag, an industrial solid waste, as the main raw material, realizing the resource utilization of waste and reducing environmental pollution. Furthermore, compared to traditional cement-based curing agents, the raw material cost of this invention can be reduced by 20-30%, and carbon emissions during cement production are significantly reduced, meeting the requirements of green, low-carbon, and sustainable development.

[0017] 4. Stable and controllable process, easy for industrial production: The preparation process of this invention has clear steps, and the parameters of each step (such as temperature, time, ratio, rotation speed, etc.) have been optimized and limited to ensure the stability and consistency of product quality. The graded granulation and low-temperature drying technologies are mature, which facilitates large-scale industrial production and has good market application prospects. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for preparing a solidifying agent adapted to the pore characteristics of soft soil according to the present invention. Detailed Implementation

[0019] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0020] Example 1 This embodiment provides a method for preparing a solidifying agent adapted to the pore characteristics of soft soil, including the following steps: Raw material pretreatment: Granulated blast furnace slag treatment: Granulated blast furnace slag with CaO content ≥35% and SiO2 content ≥30% is selected and dried at 105℃ for 3 hours to remove free moisture from the slag. Then, the dried slag is crushed and passed through a 0.075mm sieve to control its specific surface area to 400m² / kg, thus obtaining granulated blast furnace slag powder.

[0021] Lime treatment: Select calcareous lime with CaO content ≥80% and impurity content ≤5%, calcine it at 900℃ for 2.5h to enhance the activity of lime, cool it and crush it, pass it through a 0.075mm sieve to obtain lime powder.

[0022] Sodium silicate selection: Industrial-grade liquid sodium silicate is used directly, with its modulus controlled at 2.5.

[0023] Raw material mixing: Weigh 10 parts by weight of granulated blast furnace slag powder and 5 parts by weight of lime powder. Add the weighed raw materials to a double-spiral conical mixer and stir at 100 r / min for 15 min to ensure uniform mixing. Then add 25% deionized water containing 2% polyethylene glycol (PEG) and continue stirring for 15 min to obtain a mixed slurry.

[0024] Graded granulation and drying: Immediately after mixing, the slurry is fed into a spray granulator. By adjusting the nozzle orifice diameter, three grades of spherical particles with diameters of 0.1-0.2 mm, 0.2-0.3 mm, and 0.3-0.4 mm are prepared. These three grades of particles are then mixed at a mass ratio of 3:4:3 to form a particle size distribution highly matched to the pore size (0.1-0.5 mm) of the soft soil. After granulation, the mixed particles are immediately fed into a dryer and dried at 60°C for 12 hours. Slight ventilation is maintained during drying to help expel volatile polyethylene glycol gases and remove internal moisture from the particles.

[0025] Preparation of finished product: Cool the dried curing agent particles to room temperature to obtain the finished curing agent product.

[0026] Performance testing: Soft soil with a moisture content of 35% and a void ratio of 1.8 was mixed with the curing agent prepared in this embodiment at a dosage of 20% of the dry soil mass, along with 2 parts of sodium silicate. Its unconfined compressive strength was tested, and the results were: 7-day strength 1.2 MPa, 28-day strength 2.5 MPa.

[0027] Example 2 This embodiment provides a method for preparing a solidifying agent adapted to the pore characteristics of soft soil, including the following steps: Raw material pretreatment: Granulated blast furnace slag treatment: Granulated blast furnace slag with CaO content ≥35% and SiO2 content ≥30% is selected and dried at 110℃ for 2.5h. Then, the dried slag is crushed and passed through a 0.075mm sieve to control its specific surface area to 425m² / kg, thus obtaining granulated blast furnace slag powder.

[0028] Lime treatment: Select calcareous lime with CaO content ≥80% and impurity content ≤5%, calcine it at 950℃ for 2 hours, cool it, crush it, and pass it through a 0.075mm sieve to obtain lime powder.

[0029] Sodium silicate selection: Industrial-grade liquid sodium silicate is used directly, with its modulus controlled at 2.8.

[0030] Raw material mixing: Weigh 20 parts by weight of granulated blast furnace slag powder and 6 parts by weight of lime powder, add them to a double-spiral conical mixer, and stir at 120 r / min for 12 min. Then add 25% deionized water containing 2% polyethylene glycol (PEG), and continue stirring for 12 min to obtain a mixed slurry.

[0031] Grating and drying: Immediately after mixing, the slurry is fed into a spray granulator to prepare three grades of spherical particles with diameters of 0.1-0.2 mm, 0.2-0.3 mm, and 0.3-0.4 mm, which are then mixed in a mass ratio of 3:4:3. The mixed particles are dried at 70°C for 12 hours with slight ventilation.

[0032] Preparation of finished product: Cool the dried curing agent particles to room temperature to obtain the finished curing agent product.

[0033] Performance testing: Soft soil with a moisture content of 35% and a void ratio of 1.8 was mixed with the curing agent prepared in this embodiment at a dosage of 20% of the dry soil mass, along with 3 parts of sodium silicate. Its unconfined compressive strength was tested, and the results were: 7-day strength 1.5 MPa, 28-day strength 2.8 MPa.

[0034] Example 3 This embodiment provides a method for preparing a solidifying agent adapted to the pore characteristics of soft soil, including the following steps: Raw material pretreatment: Granulated blast furnace slag treatment: Granulated blast furnace slag with CaO content ≥35% and SiO2 content ≥30% is selected and dried at 120℃ for 2 hours. Then, the dried slag is crushed and passed through a 0.075mm sieve to control its specific surface area to 450m² / kg, thus obtaining granulated blast furnace slag powder.

[0035] Lime treatment: Select calcareous lime with CaO content ≥80% and impurity content ≤5%, calcine it at 1000℃ for 1.5h, cool it, crush it, and pass it through a 0.075mm sieve to obtain lime powder.

[0036] Sodium silicate selection: Industrial-grade liquid sodium silicate is used directly, with its modulus controlled at 3.0.

[0037] Raw material mixing: Weigh 30 parts by weight of granulated blast furnace slag powder and 7 parts by weight of lime powder, add them to a double-spiral conical mixer, and stir for 10 minutes at a speed of 150 r / min. Then add 25% deionized water containing 2% polyethylene glycol (PEG), and continue stirring for 10 minutes to obtain a mixed slurry.

[0038] Graded granulation and drying: Immediately after mixing, the slurry is fed into a spray granulator to prepare three grades of spherical particles with diameters of 0.1-0.2 mm, 0.2-0.3 mm, and 0.3-0.4 mm, which are then mixed in a mass ratio of 3:4:3. The mixed particles are dried at 80°C for 12 hours with slight ventilation.

[0039] Preparation of finished product: Cool the dried curing agent particles to room temperature to obtain the finished curing agent product.

[0040] Performance testing: Soft soil with a moisture content of 35% and a void ratio of 1.8 was mixed with the curing agent prepared in this embodiment at a dosage of 20% of the dry soil mass, along with 4 parts of sodium silicate. Its unconfined compressive strength was tested, and the results were: 7-day strength 1.1 MPa, 28-day strength 1.6 MPa.

[0041] Example 4 The curing agent prepared in Example 2 was subjected to long-term performance testing and compared with traditional cement-based curing agents.

[0042] Water stability coefficient: The water stability coefficient of this curing agent is 0.71 after 7 days of curing and 0.78 after 28 days of curing; while the water stability coefficients of traditional cement-based curing agents are 0.43 and 0.59 after 7 days and 28 days, respectively. The results show that the curing agent of this invention has better water stability.

[0043] Freeze-thaw stability: After 20 freeze-thaw cycles, the stability coefficient of the curing agent of this invention is 0.89, which is better than that of cement-reinforced soil (0.73), indicating that it has stronger freeze-thaw resistance.

[0044] Temperature shrinkage: In the range of 30°C to 0°C, the average shrinkage value of the curing agent of this invention is 7.2 × 10⁻⁶. -6 The value is 17.3 × 10⁻⁶ in the 0°-20° range. -6 All are far lower than those of cement-based curing agents (35.6×10). -6 and 20.2×10 -6 This indicates that it has better resistance to temperature shrinkage and can effectively reduce the generation of roadbed cracks.

[0045] Example 5 The curing agent prepared in Example 2 was used to cure soft soils with moisture contents of 25%, 30%, 35%, and 40%, respectively. The curing agent dosage was 20% of the dry soil mass, and 3 parts of sodium silicate were added. The 28-day unconfined compressive strength was tested.

[0046] The soft soil with a moisture content of 25% has a strength of 2.1 MPa after 28 days.

[0047] The soft soil with a moisture content of 30% has a strength of 1.9 MPa after 28 days.

[0048] The soft soil with a moisture content of 35% has a strength of 1.5 MPa after 28 days.

[0049] The soft soil with a moisture content of 40% has a strength of 1.3 MPa after 28 days.

[0050] Experimental results show that the curing agent of the present invention exhibits good curing effect on soft soil with different moisture contents. In particular, it can maintain high strength under high moisture content conditions, showing excellent adaptability.

[0051] In summary, the preparation method of the adaptable soft soil pore characteristic solidifier provided by the present invention achieves efficient, stable and environmentally friendly solidification of shallow soft soil through precise particle size distribution design, unique micropore structure and optimized raw material ratio and process parameters, and has extremely high industrial application value and promotion prospects.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an adaptation soft soil pore characteristic curing agent, characterized by, include: Step 1, Raw material pretreatment: Dry and crush granulated blast furnace slag to obtain granulated blast furnace slag powder; calcine and crush lime to obtain lime powder; Step 2, Raw material mixing: Weigh 10-30 parts of granulated blast furnace slag powder and 5-7 parts of lime powder by weight, mix them evenly, then add 25% deionized water containing 2% polyethylene glycol, and continue stirring to obtain a mixed slurry; Step 3, grading granulation and drying: The mixed slurry is spray-granulated to prepare three-level spherical particles with particle sizes of 0.1-0.2 mm, 0.2-0.3 mm, and 0.3-0.4 mm. The three-level spherical particles are mixed in a mass ratio of 3:4:3 to obtain mixed particles. The mixed particles are dried at 60℃-80℃ to obtain curing agent particles. Step 4, Finished product preparation: Cool the curing agent particles to obtain the final product.

2. The method of claim 1, wherein the adaptation of the soft soil pore characteristics curing agent is characterized by, In step 1, the drying temperature of the granulated blast furnace slag is 105-120℃ and the drying time is 2-3h; after crushing, it is passed through a 0.075mm sieve to control its specific surface area to be 400-450m² / kg.

3. The method of claim 1, wherein the adaptation of the soft soil pore characteristics curing agent is characterized by, In step 1, the lime is calcined at a temperature of 900-1000℃ for 1.5-2.5 hours and then pulverized and passed through a 0.075mm sieve.

4. The method of claim 1, wherein the adaptation of the soft soil pore characteristics curing agent is characterized by, In step 2, the granulated blast furnace slag powder has a CaO content ≥35%, a SiO2 content ≥30%, and a specific surface area of ​​400-450 m² / kg; the lime powder has a CaO content ≥80% and an impurity content ≤5%.

5. The method of claim 1, wherein the adaptation of the soft soil pore characteristics curing agent is characterized by, In step 2, the step of mixing evenly is carried out using a double helical conical mixer with a stirring speed of 100-150 r / min and a stirring time of 10-15 min; after adding 25% deionized water containing 2% polyethylene glycol, stirring is continued for 10-15 min.

6. The preparation method of the adaptable soft soil pore characteristic solidifying agent according to claim 1, characterized in that, In step 3, the drying time is 12 hours, and ventilation is maintained during the drying process.

7. The preparation method of the adaptable soft soil pore characteristic solidifying agent according to claim 1, characterized in that, When using the curing agent, add 2-4 parts of sodium silicate by weight, mix thoroughly, and then add it to the soft soil using a spreader; the sodium silicate is industrial-grade liquid sodium silicate with a modulus of 2.5-3.0.

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