A method for improving the water stability of laterite and the preparation of conjugate modified laterite
Patent Information
- Application Number
- CN202610930057.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-25
- Publication Date
- 2026-09-15
Smart Images
Figure CN122744191A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of red soil improvement and ecological restoration technology, specifically relating to a method for improving the water stability of red soil and the resulting conjugate improved red soil. Background Technology
[0002] Lateritic soil suffers from problems such as deep weathering, weak cementation, significant fissure development, and poor water stability. When interacting with water, lateritic soil is prone to softening and disintegration, which can lead to serious soil erosion and have an extremely adverse effect on the overall stability of lateritic soil slopes.
[0003] Lateral soils tend to form a dense soil structure after being submerged or eroded by surface water, which is very unfavorable for plant growth. Furthermore, the loss of soil fertility during soil erosion further deteriorates the plant growth environment. Lateral soils on riverbanks and reservoir slopes may also face periodic flooding. Maintaining the structural stability of lateral soils under prolonged submersion is a key issue in solving watershed ecological management.
[0004] Around water conservancy projects such as reservoirs and dams, there are a large number of drawdown zones that are affected by the periodic rise and fall of water levels. Problems such as slope stability and ecological degradation in the red soil drawdown zone area are becoming more and more serious with the operation of reservoirs and dams. Improving the water stability of red soil and the adaptability of plants plays a key role in the protection and restoration of the drawdown zone in the reservoir and dam area.
[0005] Some high-molecular polymers (such as guar gum) can cement and solidify loess and limit soil erosion; there are also reports of using bio-based polymers (such as transcription factors) to participate in the secondary metabolic processes of plants to achieve fertilizer-saving, yield-increasing, and income-enhancing effects, thereby improving crop fertilizer utilization. However, there are still few reports on improvement schemes that can simultaneously enhance the water stability and good plant adaptability of red soil. Traditional soil improvement methods usually simply add amendments to the soil and mix them, which cannot effectively improve the water stability of red soil while achieving good growth of herbaceous plants and other plants. It is highly necessary to further develop improvement processes that can achieve a conjugate enhancement of both the ecological and water stability of red soil. Summary of the Invention
[0006] The main objective of this invention is to provide a method for improving the water stability of red soil and the resulting conjugate improved red soil. This method improves red soil with high iron and aluminum oxide content, fine particles, and poor cementation into conjugate improved red soil with good water stability and plant adaptability. This can effectively enhance the ability of red soil to resist soil erosion and reservoir bank collapse, and provide a guarantee for the restoration of red soil slope ecosystem.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for improving the water stability of laterite includes the following steps: 1) Dry shear-pre-bonding Pretreated red soil and soil structure building agent (containing bio-based polymer materials and organic fertilizer) are mixed in a certain proportion and stirred at high speed (120~150r / min, 3~5min). The active groups such as amino, carboxyl and hydroxyl groups on the surface of bio-based polymer materials are activated by mechanical friction, which promotes the initial adsorption of red soil particles and organic fertilizer (or basalt fiber) to obtain pre-bound dry mixture of soil structure building agent-red soil.
[0008] 2) Shear granulation The gradient granulation process employs the following steps: First, water mist is sprayed in for wetting, followed by medium-speed rotation and stirring with a stirring paddle (75-100 r / min, 5-8 min) to initially form a cemented core; then, water mist is sprayed in a second time, and the material is sheared and stirred by a scraper (shear rate 1-10 s). -1 The time is 3-5 min), which creates a relative shearing action between the scraper and the rotating material, breaking up the excessively dense clumps formed by local over-wetting and exposing new particle contact interfaces; finally, the mixing paddle is used again for medium-speed rotation (75-100 r / min, 5-8 min) to reorganize the pre-bound dry mix into uniform and dense soil aggregates.
[0009] 3) Centrifugal mixing and compaction - natural densification and shaping process Under vertical axis centrifugal rotation conditions (75~100 r / min, 5~10 min), the agglomerates are radially rolled along the barrel wall using centrifugal force. During this period, an intermittent radial compaction step is initiated every 3~5 min (pressure 0.05~0.1 MPa, lasting 10~15 s) to strengthen the bond strength between the bio-based polymer and the laterite particles. Finally, vertical axis centrifugal rotation is continued (75~100 r / min, 3~5 min) to allow the bio-based polymer to fully penetrate and fill the internal pores of the agglomerates. After rotation is stopped, the agglomerates are allowed to stand (ambient temperature 20~30℃, time 8~12 h) to solidify, forming a conjugated modified laterite agglomerate with a dense outer layer and a porous inner layer.
[0010] In the above scheme, the pretreated red soil is obtained by removing impurities, drying, crushing and sieving the original red soil.
[0011] In the above scheme, the original red soil is mainly composed of silicon dioxide and aluminum oxide, with the sum of their mass percentages being 70-85.5%; the iron oxide content is 5-10.9%; the particle size of the pretreated red soil is 0.05-0.1 mm, and the cementing properties are poor.
[0012] In the above scheme, the impurity removal refers to removing impurities such as plant roots and gravel from the original red soil.
[0013] In the above scheme, the drying is natural air drying or oven drying.
[0014] In the above scheme, the sieving step is to pass the material through a standard sieve with a 2 mm aperture.
[0015] In the above scheme, the soil structure building agent includes a bio-based polymer amendment component and organic fertilizer, wherein the bio-based polymer amendment component can be an amino acid-based bio-based polymer material or a polysaccharide-based bio-based polymer material.
[0016] Furthermore, when the bio-based polymer material is selected as a polysaccharide-based bio-based polymer material, it can be further composited with basalt fiber.
[0017] In the above scheme, the bio-based polymer material can be one or more of the following: polyglutamic acid, soybean urease, and amino acid-based polymer materials with similar functional groups.
[0018] In the above scheme, xanthan gum and other polysaccharide-based bio-based polymer materials can be selected.
[0019] Furthermore, the molecular weight of the amino acid-based polymer is greater than 500,000 Da.
[0020] In the above scheme, the molecular weight of the polysaccharide bio-based polymer material is 4 million to 6 million Da.
[0021] In the above scheme, the components and their mass percentages in the pretreated red soil of the soil structure building agent include: 0.5-2.0% bio-based polymer amendment component; 1.5-4.0% organic fertilizer.
[0022] Furthermore, the basalt fiber accounts for 0.1% to 0.5% of the mass of the pretreated laterite.
[0023] In the above scheme, the organic fertilizer can be one or more of sheep manure, earthworm castings, chicken manure, etc.
[0024] Furthermore, the basalt fibers have a length of 1-3 mm and an aspect ratio of 50-300:1.
[0025] In the above scheme, the total water spray volume (spray volume) in steps 2) to 3) accounts for 15% to 18% of the mass of the pretreated red soil.
[0026] Furthermore, the first water mist spray accounts for 30-50% of the total water volume; the second water mist spray accounts for 20-40% of the total water volume.
[0027] The conjugate-modified laterite obtained according to the above scheme has a particle size of 0.075~5 mm and a dry density of 1.38~1.76 g / cm³. 3Furthermore, the shear strength reaches 30-60 kPa at a vertical stress of 50 kPa; the proportion of pore size (10-50 nm) reaches 45-60%; and the specific surface area is 15-35 m². 2 / g; Compared with the original red soil, the water stability can be improved by 1 to 5 times (based on LB method evaluation) and the plant germination rate can be improved by 1 to 2 times.
[0028] The present invention also provides a construction process based on the above-mentioned conjugate improved red soil, including the following steps: after the obtained conjugate improved red soil is left to stand for 12-24 hours, it is laid in the project, and the compaction degree is controlled by layer compaction to achieve more than 95% to meet the project requirements. Thanks to the excellent soil aggregate structure of the above-mentioned conjugate improved red soil, the plants sown under this compaction degree can still grow well.
[0029] The principles of this invention include: 1) Process improvement; This invention innovatively constructs a gradient red soil conjugate improvement process based on dry premixing-directional cementation-densification shaping: combining staged gradient spray wetting and mechanical shearing, rotary stirring and other means to achieve uniform dispersion and effective mixing between pretreated red soil and components such as basalt fiber, bio-based polymers (amino acids or xanthan gum), organic fertilizer, etc., to form a pre-bonded dry mix; The spray and rotary-shear synergistic granulation process is adopted. By controlling the amount of water mist added and the rotation rate of the material in stages, the bio-based polymer material is gradually wetted, spread and cemented on the surface of the red soil particles, avoiding problems such as local mudification or excessive densification of agglomerates. At the same time, the excessively large wet agglomerates are broken up by scraper shearing, exposing new particle contact interfaces, and the sheared material is re-agglomerated and reorganized, promoting the directional formation of soil aggregates with more uniform particle size and more stable structure.
[0030] Finally, vertical centrifugal rotation is performed to further enhance the bonding effect. During this process, water mist is sprayed and intermittent radial compaction is carried out to promote the effective bonding of the modified components with micro-soil particles, gradually forming a hierarchical aggregate structure with a "dense outer layer and porous interior". Through the combined effects of physical skeleton support, chemical bonding, and ionic cross-linking, the water stability, shear strength and vegetation adaptability of the red soil are significantly improved, while the damage to the soil structure caused by wet and dry cycles is weakened.
[0031] Among them, the scraper shearing process regulates the material dispersion, agglomerate breakage and recombination process, providing key process support for the subsequent "directional formation of agglomerates".
[0032] 2) Soil improvement mechanisms; The introduction of polysaccharide-based biopolymers and basalt fibers into the soil structure improver, combined with the aforementioned granulation and molding processes, facilitates the formation of a three-dimensional soil aggregate structure—a conjugated improved red soil composed of red soil particles, colloids, and fibers. This effectively increases the number of water-stable aggregates in the red soil and regulates the soil pore structure, improving the water stability of the resulting conjugated improved red soil aggregates and promoting a suitable pore environment for plant growth within the overall red soil structure. Simultaneously, the hydrophobic functional groups in the polysaccharide-based biopolymers reduce the hydrophilicity of the particles, promoting the formation of a three-dimensional conjugated improved red soil structure that is less susceptible to moisture interference. This further promotes the formation and stability of soil aggregates and significantly enhances the anti-disintegration ability of the conjugated improved red soil. In particular, the combined use of basalt fibers and polysaccharide-based biopolymers significantly reduces the amount of biopolymers required compared to traditional soil improvement methods.
[0033] The amino acid-based bio-based polymer materials introduced into the soil structure building agent contain a large number of polar groups such as amino (-NH2) and carboxyl (-COOH). These groups can undergo electrostatic adsorption and hydrogen bonding with red soil particles (mainly clay minerals with negatively charged surfaces), promoting the formation of a relatively stable "soil particle-amino acid polymer" complex.
[0034] In addition, since the original red soil is relatively infertile, organic fertilizer is further introduced into the soil structure building agent to enhance soil fertility and provide a fertility foundation for ecological restoration.
[0035] For problems such as long-term water exposure or other soil erosion on reservoir bank slopes, the corresponding conjugate improved red soil formula of this invention can be used to control the soil compaction degree to meet engineering requirements. In addition, planting local plants suitable for growth can further stabilize the soil and solve the problem of soil erosion.
[0036] Compared with the prior art, the beneficial effects of the present invention include: 1) Significantly improves soil aggregate structure and stability: Improved red soil was prepared by step spraying, gradient mixing-shearing and compaction granulation and molding method. The resulting soil aggregate structure is stable, which can effectively increase the number of water-stable aggregates in red soil, improve unstable aggregates, and promote a significant improvement in the soil's resistance to disintegration, laying the foundation for soil improvement.
[0037] 2) Significantly enhances soil mechanical properties and erosion resistance: Soil structure building agent reacts with soil through the above granulation and molding methods, improving the cohesion and internal friction angle of red soil; at the same time, the composite reinforcement effect of fiber and cementing material can enhance the bonding strength between soil particles, enabling the soil to maintain high firmness and stability in water-contaminated environments, further promoting the improvement of soil slope erosion and landslide resistance.
[0038] 3) Balancing engineering mechanics requirements with ecological benefits: The improved soil has an optimized pore structure, which can provide a good environment for plant growth, promote vegetation restoration, effectively prevent soil erosion, achieve ecological revegetation, and enhance the soil's carbon sequestration capacity. While meeting the engineering mechanics requirements of slope protection, it also achieves ecological restoration and environmental protection. Attached Figure Description
[0039] Figure 1 Unmodified original red soil morphology diagram; Figure 2 Stability test results of aggregates under different LB rapid wetting treatment schemes; Figure 3 Stability test results of aggregates under slow wetting treatment using different LB methods; Figure 4 Stability test results of aggregates under different LB method pre-wetting and disturbance treatment schemes; Figure 5 Morphology of the bio-based polymer material combined with basalt fiber to improve laterite obtained in Example 1; Figure 6 Morphology diagram of the conjugated improved red soil obtained in Example 2; Figure 7 Results of 30-day immersion of conjugate modified red soil obtained in Example 1; Figure 8 Example 1: Results of a ryegrass planting experiment; Figure 9 Example 2: Results of a ryegrass planting experiment; Figure 10 Comparative Example 1: Results of a ryegrass planting experiment. Detailed Implementation
[0040] This application will illustrate its implementation methods in detail through specific examples, so that those skilled in the art can easily understand the other advantages and performance of this application based on the content disclosed in this specification. Obviously, the embodiments described below constitute only a part of the embodiments of this application, and not all possible embodiments. This application can also be implemented or applied using other different specific implementation methods, and various details in this specification can also be modified or changed in various ways based on different perspectives and application scenarios, without departing from the core spirit of this application. It should be clearly pointed out that, in the absence of conflict, the following embodiments and their features can be combined with each other. All other embodiments that can be obtained by those skilled in the art without creative effort based on the embodiments provided in this application should be covered within the protection scope of this application.
[0041] It should be noted that the following embodiments and aspects are all within the scope of protection of the claims of this application. The solutions described herein can be implemented in various forms, and their structures and functions are merely examples. Each aspect can be implemented individually or in combination, and can also be combined with other structures and functions to realize related devices or methods.
[0042] It should also be noted that the illustrations are only for illustrating the core concept of this application and only show the relevant components. They do not reflect the actual number, specifications and layout of the components. In actual implementation, the shape, number, proportion and layout of the components can be adjusted according to the requirements.
[0043] Furthermore, the specific details are provided only to facilitate understanding of the solution, and those skilled in the art can implement the invention without such details.
[0044] In the following examples, the Le Bissonnais method and disintegration test were used to evaluate the modification characteristics of conjugate modified laterite.
[0045] Using the Le Bissonnais method, three treatment methods were implemented: rapid wetting, slow wetting, and pre-wetting followed by disturbance. This study aimed to reveal the influence of different types and dosages of modified materials on the particle size distribution characteristics and water stability of laterite aggregates.
[0046] The water stability of soil samples is quantified by observing the time and morphological changes of soil samples disintegrating in water using disintegration tests.
[0047] The Le Bissonnais method simulates different environmental conditions using rapid wetting sieving, slow wetting sieving, and pre-wetted vibrating sieving to assess the stability and erosion resistance of soil aggregates. Key indicators include average weight diameter, average geometric diameter, fractal dimension, and erodibility. This method is widely used in soil science, ecology, and agriculture. Specifically, the rapid wetting sieving (FW) method simulates the impact of heavy rainfall on soil aggregates; the slow wetting sieving (SW) method simulates the effects of light rain; and the wetting vibrating sieving (WS) method simulates the damage to soil aggregates caused by external disturbances.
[0048] The mean weight diameter (MWD) of soil aggregates is an important indicator for measuring the stability of aggregates. The larger the value, the more stable the soil structure and the stronger its resistance to erosion.
[0049] In the following examples, the original red soil (see...) Figure 1 The red clay soil was taken from typical red clay soil in Nanchang City, Jiangxi Province. It is mainly composed of silicon dioxide and aluminum oxide, with a total content of 70-85.5% and iron oxide content of 5-10.9%. It is widely distributed, thick in soil layer, severely eroded and poor in water stability. After removing plant roots, gravel and other impurities from the original red clay soil, it was naturally air-dried, crushed and passed through a standard sieve with a 2 mm aperture to obtain pretreated red clay soil.
[0050] The polysaccharide-based bio-based polymer material used, yellow collagen, has a molecular weight of 4 million to 6 million Da and is commercially available.
[0051] The basalt fibers used have a length of 1-3 mm and an aspect ratio of 50-300:1. Example 1
[0052] A method for improving the water stability of laterite includes the following steps: 1) Raw material weighing: Weigh 3 kg of pretreated red soil and a certain amount of soil structure building agent; the soil structure building agent contains 150 g of organic fertilizer (sheep manure) and polyglutamic acid (denoted as DK) used in 4 experimental groups at amounts of 15 g, 30 g, 45 g and 60 g; total spraying water = 3 kg × 16% = 0.48 kg.
[0053] 2) Preparation of conjugate modified laterite using a three-stage granulation method: 1) Dry shear-pre-bonding Pretreated red soil and soil structure building agent (including bio-based polymer materials and organic fertilizer) are mixed in a certain proportion and stirred at high speed (horizontal) using a stirring paddle (120~150r / min, 3~5min). The active groups such as amino, carboxyl, and hydroxyl groups on the surface of the bio-based polymer materials are activated by mechanical friction, which promotes the initial adsorption of the bio-based polymer materials with red soil particles and organic fertilizer (or basalt fiber) to obtain a pre-bound dry mix of soil structure building agent and red soil.
[0054] 2) Shear granulation A gradient granulation process based on variable speed and direction cementation is adopted. The specific steps include: first, initial spraying with 40% water mist (by mass of the total sprayed water) followed by medium-speed (horizontal) rotary stirring (100 r / min, 5 min) to initially form a cemented core; the stirring shaft used is a stirring paddle; then, a second spraying with 60% water mist (by mass of the total sprayed water) is performed simultaneously using a scraper to shear and stir the material (shear rate 1~10 s). -1 (3 min) to break up overly dense clumps, and finally use a stirring paddle to rotate at medium speed (horizontal) (75 r / min, 5 min) to reorganize the pre-bound dry mix into uniform and dense soil aggregates.
[0055] 3) Centrifugal mixing and compaction - natural densification and shaping process Under vertical axis centrifugal rotation (100 r / min), the agglomerates are radially tumbled along the barrel wall using centrifugal force. An intermittent radial compaction step (pressure 0.05 MPa, lasting 10 s) is initiated every 3 min to strengthen the bond between the bio-based polymer and the laterite particles. Finally, the vertical axis centrifugal rotation is maintained (90 r / min, 5 min) to promote the full penetration and filling of the internal pores of the agglomerates by the bio-based polymer. After the rotation stops, the agglomerates are allowed to stand (ambient temperature 20~30℃, time 8~12 h) to solidify, resulting in the conjugated modified laterite agglomerates (particle size 0.075~5 mm). Example 2
[0056] A method for improving the water stability of laterite includes the following steps: 1) Raw material weighing: Weigh 3 kg of pretreated red soil and a certain amount of soil structure building agent, which includes 12 g of basalt fiber and 150 g of organic fertilizer (sheep manure) and xanthan gum (denoted as XG) used in 4 experimental groups at amounts of 15 g, 30 g, 45 g and 60 g respectively; Total water spraying volume = 3 kg × 16% = 0.48 kg.
[0057] 2) Preparation of conjugate modified laterite using a three-stage granulation method: 1) Dry shear-pre-bonding Pretreated red soil and soil structure building agent (containing bio-based polymer materials and organic fertilizer) are mixed in a certain proportion and stirred at high speed (120~150r / min, 3~5min) using a stirring paddle. The active groups such as amino, carboxyl, and hydroxyl groups on the surface of the bio-based polymer materials are activated by mechanical friction, which promotes the initial adsorption of the bio-based polymer materials with red soil particles and organic fertilizer (or basalt fiber) to obtain a pre-bound dry mixture of soil structure building agent and red soil.
[0058] 2) Shear granulation A gradient granulation process based on variable speed and direction cementation is adopted. The specific steps include: firstly, initial spraying with water mist accounting for 40% of the total sprayed water volume, followed by medium-speed rotation and stirring (100 r / min, 5 min) to initially form a cemented core; the stirring shaft used is a stirring paddle; then, a second spraying with water mist accounting for 60% of the total sprayed water volume is carried out, while simultaneously using a scraper to shear and stir the material (shear rate of 1~10 s). -1 (3 min) to break up overly dense clumps, and finally use a stirring paddle to rotate at medium speed (75 r / min, 5 min) to reorganize the pre-bound dry mix into uniform and dense soil aggregates.
[0059] 3) Centrifugal mixing and compaction - natural densification and shaping process Under vertical axis centrifugal rotation (100 r / min), the agglomerates are radially rolled along the barrel wall using centrifugal force. An intermittent radial compaction step (pressure 0.05 MPa, lasting 10 s) is initiated every 3 min to strengthen the bond between the bio-based polymer and the laterite particles. Finally, the vertical axis centrifugal rotation is maintained (90 r / min, 5 min) to promote the full penetration and filling of the internal pores of the agglomerates by the bio-based polymer. After the rotation stops, the agglomerates are allowed to stand (ambient temperature 20~30℃, time 8~12 h) to solidify, thus obtaining the conjugated modified laterite agglomerates.
[0060] Comparative Example 1 An improved red soil is prepared by directly adding 16% of the mass of water to 30 kg of pretreated red soil and stirring in a unidirectional horizontal rotation (stirring rate of 100 r / min, stirring time of 5 min).
[0061] The improved red soil described in the above examples and comparative examples was tested for polar water stability and plant adaptability, respectively. The specific methods are as follows: 1) The water stability of conjugate modified laterite aggregates was tested using the LB method; 2) Based on the LB test results, 1% polyglutamic acid was selected and long-term immersion test was used to verify the stability of soil structure under immersion conditions of the conjugate red soil improvement formula.
[0062] 3) Select ryegrass suitable for growth in Nanchang and conduct planting experiments on the red soil prepared in Example 1, Example 2 and Comparative Example 1 to verify the plant adaptability of conjugate improved red soil.
[0063] 4) Specific surface area and pore size analysis were performed using BSD-PS2. The specific test results are as follows: Depend on Figure 2 , Figure 3 and Figure 4 The LB method test results show that the conjugate improved red soil Example 2 (xanthan gum + basalt fiber) prepared by the three-stage granulation method has the most outstanding effect. The MWD values of the three conditions of fast wetting, slow wetting and pre-wetting rapidly reach the peak at low dosage, making the soil enter the "extremely stable" state, but the effect will decrease if the dosage is excessive. The comparison of the MWD values of Example 1 (polyglutamic acid) and Comparative Example 1 shows that although the water stability improvement effect of Example 1 is slightly worse than that of Example 2, the water stability of the conjugate improved red soil in Example 1 is also significantly improved compared with the water stability of the original red soil.
[0064] Depend on Figure 1 , Figure 5 and Figure 6 The morphology images of the unmodified laterite and the conjugate modified laterite obtained in Examples 1 and 2 show that the conjugate modified laterite prepared by the three-stage granulation method has a higher morphology than the unmodified laterite. Figure 1 The red soil aggregates in pure red soil are significantly larger and more numerous.
[0065] Depend on Figure 7 The results of the immersion test on the conjugate improved red soil obtained in Example 1 show that although numerous deep and interconnected cracks appeared on the surface of the improved red soil after immersion for 30 days, even penetrating the entire sample, its main structure remained stable in the water without disintegration. Furthermore, soil particles detached from the sample could flocculate and aggregate, keeping the water clear. The results indicate that the improved red soil obtained in this invention can maintain good soil structural stability even under long-term immersion conditions.
[0066] Depend on Figure 8 , Figure 9 and Figure 10 The planting results of ryegrass after 30 days show that the growth of ryegrass in both Example 1 and Example 2 is generally better than that in Comparative Example 1. This indicates that the soil structure-building agent formulation of the present invention can effectively improve the plant adaptability of red soil.
[0067] The specific surface area and average pore diameter of the laterite prepared in Comparative Example 1 were 34.42 m². 2 / g and 7.91 nm, and the proportions of pore volume in the five pore size ranges of <2 nm, 2-5 nm, 5-10 nm, 10-50 nm and >50 nm to the total pore volume are 1.88%, 25.93%, 16.95%, 37.92% and 17.32%, respectively.
[0068] The specific surface area and average pore diameter of the conjugate modified laterite prepared in Example 1 were 30.94 m². 2 The pore size is 9.26 nm, and its porosity is characterized by a decrease in the pore proportions of <2 nm, 2~5 nm and 5~10 nm pore sizes to 1.49%, 25.03% and 16.52%, respectively, with reductions of 20.74%, 3.47% and 2.54%; while the pore proportion of 10~50 nm pore size increases to 45.01%, with an increase of 18.7%.
[0069] The specific surface area and average pore diameter of the conjugate modified laterite prepared in Example 2 were 30.94 m². 2 The pore size is 17.37 nm, and its porosity is characterized by a decrease in the pore proportions of <2 nm, 2~5 nm and 5~10 nm pore sizes to 0.22%, 13.98% and 13.9%, respectively, with reductions of 88.3%, 46.09% and 17.99%; while the pore proportion of 10~50 nm pore sizes increases significantly, reaching a maximum of 55.35%, with an increase of 45.97%.
[0070] Combination Figure 5 and Figure 6 The distinctly dense outer layer of the conjugated modified laterite, along with the variations in specific surface area and average pore diameter mentioned above, indicates that the conjugated modified laterite prepared by this invention has a dense outer layer and a porous interior. Further measurements show that the specific surface area of the modified laterite obtained by this invention is 15-35 m². 2 / g.
[0071] Based on the above conclusions, the following engineering recommendations are given: ① In areas with prolonged waterlogging, it is recommended to use a three-stage granulation method to prepare Formula 1, incorporating 2% of the amino acid-based bio-based polymer material polyglutamic acid to improve the water stability and plant adaptability of red soil; ② In areas with perennial rainfall, it is recommended to use a three-stage granulation method to prepare Formula 2, incorporating 0.5% of the polysaccharide-based bio-based polymer material xanthan gum and 0.4% basalt fiber in a conjugate ratio to improve the water stability and plant adaptability of red soil.
[0072] The above description is merely a specific embodiment of this application; however, the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims.
Claims
1. A method for improving the water stability of laterite, characterized in that, Includes the following steps: 1) Dry shear-pre-bonding Pretreated red soil and soil structure building agent are mixed in proportion and stirred at high speed to obtain pre-bonded dry mix. 2) Shear granulation For the obtained pre-bound dry mix, water mist is first sprayed in while medium-speed rotation and stirring are performed; then water mist is sprayed in a second time while shearing and stirring the material; then medium-speed rotation and stirring are continued. 3) Centrifugal mixing, compaction, and shaping process Under the condition of centrifugal rotation of the vertical axis, an intermittent radial compaction step is initiated; finally, the centrifugal rotation of the vertical axis is maintained; and the soil is left to stand and solidify to form the conjugate improved red soil.
2. The method for improving the water stability of laterite according to claim 1, characterized in that, Pretreated red soil is obtained by removing impurities, drying, crushing and sieving the original red soil.
3. The method for improving the water stability of laterite according to claim 1, characterized in that, The original red soil mainly consists of silicon dioxide and aluminum oxide, with a combined mass percentage of 70-85.5%; iron oxide content is 5-10.9%; and the particle size of the red soil is 0.05-0.1 mm.
4. The method for improving the water stability of laterite according to claim 1, characterized in that, The soil structure improver comprises a bio-based polymer amendment and organic fertilizer, wherein the bio-based polymer amendment is an amino acid-based bio-based polymer or a polysaccharide-based bio-based polymer.
5. The method for improving the water stability of laterite according to claim 4, characterized in that, The soil structure building agent comprises the following components and their mass percentages in the pretreated red soil: 0.5-2.0% bio-based polymer amendment and 1.5-10.0% organic fertilizer.
6. The method for improving the water stability of laterite according to claim 4, characterized in that, The organic fertilizer is one or more of sheep manure, earthworm castings, and chicken manure.
7. The method for improving the water stability of laterite according to claim 1, characterized in that, In steps 2) to 3), the total water mist volume accounts for 15% to 18% of the pretreated red soil mass; The first spray of water mist accounts for 30-50% of the total water mist volume; the second spray of water mist accounts for 50-70% of the total water mist volume.
8. The method for improving the water stability of laterite according to claim 1, characterized in that, In step 1), the high-speed rotary stirring is performed at a speed of 120~150 r / min for 3~5 min. In step 2), the speed of a single medium-speed rotary stirring is 75~100 r / min, and the time is 5~8 min; the shear stirring uses a shear rate of 1~10 s. -1 The time is 3 to 5 minutes.
9. The method for improving the water stability of laterite according to claim 1, characterized in that, In step 3), the centrifugal rotation speed is 75~100 r / min and the time is 5~10 min; a radial compaction step is started every 3~5 min, the radial compaction pressure is 0.05~0.1 MPa and the time is 5~10 s; finally, centrifugal rotation is continued at 75~100 r / min for 3~5 min.
10. The conjugate modified laterite prepared by the method for improving the water stability of laterite according to any one of claims 1 to 9, characterized in that, Its particle size is 0.075~5 mm; shear strength reaches 30~60 kPa; pore size of 10~50 nm accounts for 45~60%; specific surface area is 15~35 m². 2 / g.