Loess modifier based on fly ash-polyacrylamide and preparation method thereof

Abstract

The invention belongs to the technical field of loess improvement, and particularly discloses a loess improver based on fly ash-polyacrylamide and a preparation method of the loess improver based on fly ash-polyacrylamide, and the loess improver comprises the following components in parts by mass: 84.5-94.85 parts of natural loess; 5 to 15 parts of fly ash; and 0.15 to 0.5 part of anionic polyacrylamide. According to the loess modifier based on the fly ash-polyacrylamide, a soil body structure is optimized through a filling-cementing synergistic mechanism, pores are effectively filled with the fly ash microspheres and colloidal products thereof, and the anionic polyacrylamide forms cementing bridging among particles, so that point contact among the particles is promoted to be converted into surface inlay contact together, and the loess modifier has the advantages that the soil body structure is optimized; the compactness of the soil body is obviously enhanced, so that the synchronous improvement of the shear strength and the anti-permeability performance is realized.

Description

Technical Field

[0001] This invention belongs to the field of loess improvement technology, and discloses a loess conditioner based on fly ash-polyacrylamide and its preparation method. Background Technology

[0002] Traditional loess is widely distributed in Northwest my country. Due to its well-developed vertical joints, porous structure, and weak cementation, it exhibits significant collapsibility, low strength, and easy disintegration, making it prone to landslides and collapses under rainfall and engineering disturbances, seriously threatening infrastructure and ecological security. Currently, lime, cement, slag, fly ash, and polymer materials are commonly used to improve loess in engineering projects, but these are mostly based on single materials, resulting in limited strength improvement or insufficient durability. Summary of the Invention

[0003] The purpose of this invention is to provide a loess conditioner based on fly ash-polyacrylamide and its preparation method, so as to solve the technical problems of limited strength improvement or insufficient durability of existing loess conditioners.

[0004] The first aspect of the present invention provides a loess conditioner based on fly ash-polyacrylamide, comprising, by weight parts:

[0005] Natural loess: 84.5~94.85 parts;

[0006] Fly ash: 5-15 parts;

[0007] Anionic polyacrylamide: 0.15~0.5 parts.

[0008] Preferably, the anionic polyacrylamide has a molecular weight of 10 million to 15 million.

[0009] Preferably, the chemical composition of the fly ash includes SiO2, Al2O3, Fe2O3, CaO, and MgO.

[0010] Preferably, the mass ratio of fine ash to coarse ash in the fly ash is 7:3;

[0011] The particle size of the fine ash particle ratio 81%;

[0012] The coarse ash has a medium particle size particle ratio 51%.

[0013] Preferably, the particle size of the natural loess is ≤2mm.

[0014] A second aspect of the present invention provides a method for preparing a loess amendment based on fly ash-polyacrylamide, comprising:

[0015] Step 1: Prepare a homogeneous solution of anionic polyacrylamide;

[0016] Step 2: Add natural loess and fly ash to the homogeneous solution and mix thoroughly to obtain a mixture;

[0017] Step 3: Curing the mixture under sealed conditions at room temperature to obtain a loess conditioner.

[0018] Preferably, step 1 specifically includes:

[0019] Dissolve 0.15-0.5 parts of anionic polyacrylamide in 11.49 parts of water to obtain a homogeneous solution.

[0020] Preferably, the curing temperature in step 3 is 25±2℃, and the curing time is 20 to 30 hours.

[0021] The fly ash-polyacrylamide-based loess conditioner and its preparation method of the present invention have the following advantages compared with the prior art:

[0022] The loess conditioner based on fly ash and polyacrylamide of the present invention optimizes the soil structure through a "filling-cementing" synergistic mechanism. Fly ash microspheres and their colloidal products effectively fill the pores, while anionic polyacrylamide forms cementing bridges between particles. Together, they promote the transformation of particle contact from point contact to surface embedding contact, which significantly enhances the compactness of the soil, thereby achieving a simultaneous improvement in shear strength and impermeability.

[0023] The fly ash-polyacrylamide-based loess conditioner of the present invention can significantly enhance the shear strength of the soil, improve the cohesion of loess, improve its impermeability, and reduce its permeability coefficient. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the preparation method of the loess amendment based on fly ash-polyacrylamide according to an embodiment of the present invention.

[0025] Figure 2 The images show the cohesion diagrams of the ring cutter samples from Examples 1 to 9 and Comparative Examples 1 to 6 of the present invention.

[0026] Figure 3 The diagram shows the permeability coefficients of the ring cutter samples from Examples 1 to 9 and Comparative Examples 1 to 6 of this invention. Detailed Implementation

[0027] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0028] A first aspect of this invention provides a loess conditioner based on fly ash-polyacrylamide, comprising, by weight parts:

[0029] Natural loess: 84.5~94.85 parts;

[0030] Fly ash: 5-15 parts;

[0031] Anionic polyacrylamide: 0.15~0.5 parts.

[0032] The loess conditioner based on fly ash and polyacrylamide of the present invention optimizes the soil structure through a "filling-cementing" synergistic mechanism. Fly ash microspheres and their colloidal products effectively fill the pores, while anionic polyacrylamide (APAM) forms cementing bridges between particles, which together promote the transformation of particle contact from point contact to surface embedding contact, significantly enhancing the compactness of the soil, thereby achieving a simultaneous improvement in shear strength and impermeability.

[0033] The fly ash-polyacrylamide-based loess conditioner of the present invention can significantly enhance the shear strength of the soil, improve the cohesion of loess, improve its impermeability, and reduce its permeability coefficient.

[0034] The molecular weight of anionic polyacrylamide has a significant impact on its ability to form a cementitious bridging structure between particles. Higher molecular weight and longer polymer chains are more conducive to forming an effective bridging structure, thereby enhancing the flocculation effect. However, excessively high molecular weight can lead to problems such as difficulty in dissolution and increased solution viscosity. In this embodiment of the invention, to balance bridging structure and dissolution performance, the molecular weight of the anionic polyacrylamide used is limited to 10 million to 15 million, preferably 10 million.

[0035] The chemical composition of the fly ash in this embodiment of the invention includes SiO2, Al2O3, Fe2O3, CaO, and MgO, and the pH value of the fly ash is... 10. The pozzolanic activity of fly ash mainly depends on its glass phase content and chemical composition ratio. SiO2 and Al2O3 are the key active components in the pozzolanic reaction. When in contact with loess under alkaline conditions, they generate cementitious substances such as hydrated calcium silicate. Fly ash microspheres and cementitious substances can effectively fill pores, thereby improving the compactness of loess. In the embodiments of this invention, the total content of SiO2 and Al2O3 is 70%~80%, and the mass ratio of Al2O3 to SiO2 is 1:1.5~3. This ratio range maximizes the pozzolanic activity, resulting in the generation of more cementitious substances. In the embodiments of this invention, the CaO content is 10.27%~15.5%, and the MgO content is 1.11%~2.74%. The CaO and MgO used in the above-mentioned dosage range can promote the formation of the glass phase or participate in the reaction, without inhibiting the activity or affecting the stability. In the embodiments of the present invention, the Fe2O3 content is 4.79% to 7.7%. Fe2O3 in this range can lower the ash melting point, help form more glass particles, and will not reduce the activity of the pozzolanic reaction due to excessive content.

[0036] This invention uses fly ash to fill the pores of natural loess. Since fly ash is a typical solid waste from coal-fired power plants, its storage not only occupies a large amount of land, but may also cause dust and groundwater pollution. Using it for loess improvement can not only realize the resource utilization of fly ash, but also significantly improve the shear strength and impermeability of loess through physical improvement mechanisms. It is an economical and environmentally friendly loess improvement path with important theoretical guiding significance and engineering application prospects.

[0037] In this embodiment of the invention, the fly ash consists of fine ash and coarse ash, with a fine ash:coarse ash ratio of 7:3. The specific particle size range is shown in Table 1. Within this particle size range, the fly ash has a large surface area, allowing for a more complete pozzolanic activation reaction.

[0038] Table 1. Particle composition of fly ash

[0039]

[0040] In this embodiment of the invention, the particle size of the natural loess is ≤2mm. Natural loess within this particle size range has a large specific surface area, which allows it to fully contact the active components in fly ash, promote the pozzolanic reaction, and generate substances such as hydrated calcium silicate (CSH), thereby improving the loess structure.

[0041] A second aspect of the present invention provides a method for preparing a loess amendment based on fly ash-polyacrylamide, comprising:

[0042] Step 1: Prepare a homogeneous solution of anionic polyacrylamide.

[0043] For example, 0.15 to 0.5 parts of anionic polyacrylamide are dissolved in 11.49 parts of water to obtain a homogeneous solution.

[0044] The anionic polyacrylamide of this invention is a white crystalline particle, odorless, neutral, and easily soluble in water to form a uniform and transparent viscous liquid, with strong adsorption and flocculation capabilities.

[0045] Step 2: Add 84.5~94.85 parts of natural loess and 5~15 parts of fly ash to the homogenized solution in Step 1, mix thoroughly to obtain a mixture. Since the moisture content of natural loess is typically 11.49%, it needs to be dried to avoid affecting the improvement effect.

[0046] Step 3: Curing the mixture under sealed conditions at room temperature yields a loess conditioner. The curing temperature is 25±2℃, and the curing time is 20 to 30 hours, preferably 24 hours.

[0047] The preparation method of the present invention has the advantages of simple process, low cost and environmental friendliness.

[0048] The technical effects of the fly ash-polyacrylamide-based loess conditioner of the present invention will be verified below with more specific embodiments.

[0049] Example 1

[0050] In this embodiment, the raw materials are composed of the following components by mass: 94.85 parts of natural loess, 5 parts of fly ash, 0.15 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0051] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The anionic polyacrylamide solution is then uniformly mixed with the dried loess and fly ash (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0052] Example 2

[0053] In this embodiment, the raw materials are composed of the following components by mass: 94.7 parts of natural loess, 5 parts of fly ash, 0.30 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0054] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The anionic polyacrylamide solution is then uniformly mixed with the dried loess and fly ash (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0055] Example 3

[0056] In this embodiment, the raw materials are composed of the following components by mass: 94.5 parts of natural loess, 5 parts of fly ash, 0.50 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0057] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The anionic polyacrylamide solution is then uniformly mixed with the dried loess and fly ash (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0058] Example 4

[0059] In this embodiment, the raw materials are composed of the following components by mass: 89.85 parts of natural loess, 10 parts of fly ash, 0.15 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0060] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The anionic polyacrylamide solution is then uniformly mixed with the dried loess and fly ash (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0061] Example 5

[0062] In this embodiment, the raw materials are composed of the following components by mass: 89.7 parts of natural loess, 10 parts of fly ash, 0.30 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0063] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The anionic polyacrylamide solution is then uniformly mixed with the dried loess and fly ash (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0064] Example 6

[0065] In this embodiment, the raw materials are composed of the following components by mass: 89.5 parts of natural loess, 10 parts of fly ash, 0.50 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0066] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The anionic polyacrylamide solution is then uniformly mixed with the dried loess and fly ash (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0067] Example 7

[0068] In this embodiment, the raw materials are composed of the following components by mass: 84.85 parts of natural loess, 15 parts of fly ash, 0.15 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0069] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The anionic polyacrylamide solution is then uniformly mixed with the dried loess and fly ash (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0070] Example 8

[0071] In this embodiment, the raw materials are composed of the following components by mass: 84.7 parts of natural loess, 15 parts of fly ash, 0.30 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0072] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The anionic polyacrylamide solution is then uniformly mixed with the dried loess and fly ash (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0073] Example 9

[0074] In this embodiment, the raw materials are composed of the following components by mass: 84.5 parts of natural loess, 15 parts of fly ash, 0.50 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0075] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The anionic polyacrylamide solution is then uniformly mixed with the dried loess and fly ash (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0076] Comparative Example 1

[0077] In this comparative example, the raw materials are composed of the following parts by mass: 95 parts natural loess, 5 parts fly ash, and 11.49 parts distilled water.

[0078] The preparation method is as follows: Natural loess is dried and passed through a 2mm sieve. The dried loess that has passed through the 2mm sieve is then uniformly mixed with fly ash and homogenized. The mixture is then sealed and cured at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0079] Comparative Example 2

[0080] In this comparative example, the raw materials are composed of the following parts by mass: 90 parts natural loess, 10 parts fly ash, and 11.49 parts distilled water.

[0081] The preparation method is as follows: Natural loess is dried and passed through a 2mm sieve. The dried loess that has passed through the 2mm sieve is then uniformly mixed with fly ash and homogenized. The mixture is then sealed and cured at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0082] Comparative Example 3

[0083] In this comparative example, the raw materials are composed of the following parts by mass: 85 parts natural loess, 15 parts fly ash, and 11.49 parts distilled water.

[0084] The preparation method is as follows: Natural loess is dried and passed through a 2mm sieve. The dried loess that has passed through the 2mm sieve is then uniformly mixed with fly ash and homogenized. The mixture is then sealed and cured at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0085] Comparative Example 4

[0086] In this comparative example, the raw materials are composed of the following parts by mass: 99.85 parts of natural loess, 0.15 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0087] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The polyacrylamide solution is then uniformly mixed with the dried loess (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0088] Comparative Example 5

[0089] In this comparative example, the raw materials are composed of the following parts by mass: 99.7 parts of natural loess, 0.30 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0090] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The polyacrylamide solution is then uniformly mixed with the dried loess (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0091] Comparative Example 6

[0092] In this comparative example, the raw materials are composed of the following parts by mass: 99.5 parts of natural loess, 0.50 parts of anionic polyacrylamide, and 11.49 parts of distilled water.

[0093] The preparation method is as follows: Anionic polyacrylamide is dissolved in distilled water according to the designed ratio. Natural loess is dried and passed through a 2mm sieve. The polyacrylamide solution is then uniformly mixed with the dried loess (passed through a 2mm sieve), homogenized, and cured in a sealed container at room temperature (25±2℃) for 24 hours. The mixture is then pressed using a static pressing method according to its natural density (ρ=1.78 g / cm³). 3 Different sizes of ring cutter samples (Φ61.8 mm × 20 mm and Φ61.8 mm × 40 mm) were pressed separately, with a sample preparation pressure of 50 kN. The pressed ring cutter samples were left to stand for 10 min.

[0094] Direct shear tests were conducted with vertical pressures set to 100 kPa, 200 kPa, 300 kPa, and 400 kPa. The shear strengths of Examples 1 to 9 and Comparative Examples 1 to 6 are shown in Table 2.

[0095] Table 2 Shear strength (kPa) of Examples 1-9 and Comparative Examples 1-6

[0096]

[0097] The cohesive strength of Examples 1 to 9 and Comparative Examples 1 to 6 is as follows: Figure 2 As shown.

[0098] The permeability coefficients of Examples 1 to 9 and Comparative Examples 1 to 6 are as follows: Figure 3 As shown.

[0099] Table 1 shows that when fly ash is applied alone to improve loess, the shear strength gradually increases with increasing dosage. Under low pressure (100 kPa~200 kPa), fly ash has little effect on improving the shear strength of loess, while under high pressure (300 kPa~400 kPa), fly ash has a significant effect on improving shear strength, reaching its maximum at a dosage of 15%. When anionic polyacrylamide is applied alone to improve loess, the shear strength first increases and then decreases with increasing anionic polyacrylamide dosage, reaching its maximum value at a dosage of 0.3%. When using a fly ash-polyacrylamide composite to improve loess, the effect of different fly ash dosages on improving shear strength is minimal, almost unchanged, when the anionic polyacrylamide dosage is 0.15%. When the anionic polyacrylamide dosage is 0.5%, the effect of fly ash on improving shear strength is better under high pressure (300 kPa~400 kPa) than under low pressure (100 kPa~200 kPa). When the anionic polyacrylamide dosage is 0.3%, different fly ash dosages significantly improve shear strength, and the shear strength of the composite-improved loess is generally better than other formulations (0.15% anionic polyacrylamide and 0.5% anionic polyacrylamide). Among these, the sample with 10% fly ash and 0.3% anionic polyacrylamide has the highest overall shear strength and the best improvement effect.

[0100] from Figure 2It can be seen that when anionic polyacrylamide is added alone, the cohesion of the improved loess shows a trend of first increasing and then decreasing with the change of the anionic polyacrylamide dosage. Specifically, when the anionic polyacrylamide dosage increases from 0% to 0.3%, the cohesion significantly increases from 28.8 kPa in plain loess to 35.28 kPa (an increase of about 22.5%); when the dosage continues to increase to 0.5%, the cohesion slightly decreases to 32.1 kPa, but is still higher than that of plain loess. When fly ash is added alone, the effect of dosage on the cohesion of the improved loess shows a similar pattern: when the fly ash dosage is 5%, the cohesion reaches a local peak of 30.16 kPa (an increase of 4.7% compared to plain loess). However, as the fly ash dosage continues to increase, the cohesion decreases rapidly, even falling below the cohesion level of plain loess. This phenomenon may be because after the fly ash dosage exceeds the critical threshold, the dense accumulation of microspherical particles causes a change in the contact mode, thus forming a sand-like skeleton structure. The improvement effect of fly ash-polyacrylamide composite on the cohesion of loess is particularly significant. With a fly ash content of 10% and anionic polyacrylamide content of 0.3%, the cohesion of the improved loess reached 49.6 kPa, an increase of 72.2% compared to the 28.8 kPa of plain loess. Under other different ratios, the trend of cohesion variation varied depending on the specific dosages of fly ash and anionic polyacrylamide. This phenomenon is mainly attributed to the synergistic working mechanism between the filling effect of fly ash and the cementing effect of anionic polyacrylamide. Both optimize the internal structure and enhance the density of the loess, thus significantly improving cohesion. This synergistic effect is optimal at a fly ash content of 10% and anionic polyacrylamide content of 0.3%. Insufficient anionic polyacrylamide content makes it difficult to fully utilize the filling effect of fly ash, while excessive content leads to over-concentration of the cementing effect; conversely, excessive fly ash content reduces the structural density due to loosening of the particle skeleton, thereby weakening cohesion. Therefore, the dosage of both fly ash and anionic polyacrylamide must be controlled within a reasonable range to ensure optimal improvement.

[0101] from Figure 3 It can be seen that when fly ash or anionic polyacrylamide is added alone, the permeability coefficient of the soil samples decreases to varying degrees with the increase of the material dosage. Among them, the effect of adding anionic polyacrylamide on reducing permeability is particularly significant, with the change approaching one order of magnitude. When using fly ash-polyacrylamide composite to improve loess, there is an optimal ratio scheme for the inhibition of loess permeability. When the fly ash dosage is 5% and the anionic polyacrylamide dosage is 0.5%, the permeability coefficient of the improved loess reaches the lowest value. Compared to unmodified loess, the permeability was reduced by approximately 91.7%. With a constant fly ash content, the permeability coefficient decreased significantly with increasing anionic polyacrylamide content. This effect was more pronounced at higher fly ash levels. This indicates a synergistic effect between fly ash and anionic polyacrylamide, effectively reducing the permeability of modified loess.

[0102] This invention utilizes industrial solid waste fly ash combined with environmentally friendly anionic polyacrylamide to achieve complementary advantages. It not only enables the resource utilization of fly ash, but also significantly improves the shear strength and impermeability of loess through physical modification mechanisms. It is an economical and environmentally friendly loess improvement path with important theoretical guidance and engineering application prospects.

[0103] The above descriptions are merely a few embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications or alterations made by those skilled in the art without departing from the scope of the technical solution of the present invention using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A loess conditioner based on fly ash-polyacrylamide, characterized in that, By weight, including: Natural loess: 84.5~94.85 parts; Fly ash: 5-15 parts; Anionic polyacrylamide: 0.15~0.5 parts.

2. The loess conditioner based on fly ash-polyacrylamide according to claim 1, characterized in that, The anionic polyacrylamide has a molecular weight of 10 million to 15 million.

3. The loess conditioner based on fly ash-polyacrylamide according to claim 1, characterized in that, The chemical composition of the fly ash includes SiO2, Al2O3, Fe2O3, CaO, and MgO.

4. The loess conditioner based on fly ash-polyacrylamide according to claim 3, characterized in that, The mass ratio of fine ash to coarse ash in the fly ash is 7:3; The particle size of the fine ash particle ratio 81%; The coarse ash has a medium particle size particle ratio 51%.

5. The loess conditioner based on fly ash-polyacrylamide according to claim 1, characterized in that, The particle size of the natural loess is ≤2mm.

6. A method for preparing a loess conditioner based on fly ash-polyacrylamide as described in any one of claims 1-5, characterized in that, include: Step 1: Prepare a homogeneous solution of anionic polyacrylamide; Step 2: Add natural loess and fly ash to the homogeneous solution and mix thoroughly to obtain a mixture; Step 3: Curing the mixture under sealed conditions at room temperature to obtain a loess conditioner.

7. The method for preparing the loess conditioner based on fly ash-polyacrylamide according to claim 6, characterized in that, Step 1 is as follows: Dissolve 0.15-0.5 parts of anionic polyacrylamide in 11.49 parts of water to obtain a homogeneous solution.

8. The method for preparing the loess conditioner based on fly ash-polyacrylamide according to claim 6, characterized in that, In step 3, the curing temperature is 25±2℃ and the curing time is 20 to 30 hours.

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