A method of preparing an impervious cushion layer from solidified aeolian sand

Abstract

The present application relates to the technical field of building materials, in particular to a method for preparing an impermeable cushion layer from solidified aeolian sand, comprising the following steps: S1, batching: 55-65 parts of aeolian sand, 30-40 parts of construction waste and 5-10 parts of Portland cement are weighed as raw materials; S2, mixing: the raw materials are stirred uniformly, and then a thickening agent, an expanding agent, additional water, a water reducing agent and an impermeable agent are added in sequence, and the mixture is stirred again to obtain a mixed material; S3, forming: the mixed material is pressed into a solidified aeolian sand, and then cured for 26-30 days to obtain the impermeable cushion layer. The aeolian sand and the construction waste are used together, the aeolian sand can effectively prevent frost heaving, the construction waste can promote the cementation of the components and improve the impermeability of the impermeable cushion layer, and the aeolian sand and the construction waste are both existing materials in desert areas, which can effectively reduce transportation costs.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a method for preparing an impermeable cushion layer from solidified aeolian sand. Background Technology

[0002] In desert and Gobi regions, sand particles frequently fill the air, and these flying sands, carried by strong winds, settle on farmland, ditches, and buildings. This sand not only damages the environment but also severely impacts people's lives. After settling, this sand forms aeolian sand. With the continuous expansion of engineering construction in desert areas, building materials have become increasingly scarce. Gravel, clay, and other materials need to be transported from other regions over long distances, significantly increasing the cost of engineering projects in desert areas. However, aeolian sand is a material abundant in these areas. Its fine particles, extremely low clay content, and excellent water stability make it easy to compact when saturated with water. Based on these characteristics, and through appropriate solidification and compaction methods, aeolian sand can be used as a primary building material in engineering construction.

[0003] The solidification of aeolian sand for construction has both theoretical basis and practical significance. Currently, various solidification methods based on organic-inorganic active materials such as slag, cement, water glass, lime, and polymer modifiers have been developed, and aeolian sand is widely used in engineering fields such as concrete, building mortar, and roadbed fillers. This method can rapidly and massively utilize aeolian sand, turning waste into treasure, and also reduce the extraction of natural sand, gravel, and clay resources, promoting the green and sustainable development of infrastructure construction. However, the application environment of aeolian sand in actual engineering projects is complex and variable, and its large-scale application still faces the following key technical challenges that need to be addressed:

[0004] First, most existing engineering practices and research have used aeolian sand as a road construction material. However, due to the high permeability and loose, non-cohesive characteristics of aeolian sand, there is insufficient research on its application in hydraulic structures. There is a lack of systematic research on its permeability, seepage failure modes, and seepage stability under hydraulic action, and the available results are limited.

[0005] Furthermore, the solidification technology for aeolian sand is cumbersome and complex, making it difficult to balance performance and solidification cost. Some solidifying agents pose certain hazards to the surrounding environment, requiring assurance that environmental risks are controllable during long-term use, thus making it difficult to develop an economical, efficient, and environmentally friendly solidification solution. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a method for preparing an impermeable cushion layer from solidified aeolian sand.

[0007] The technical solution of this invention is: a method for preparing an impermeable cushion layer from solidified aeolian sand, comprising the following steps:

[0008] S1. Ingredients:

[0009] Weigh out 55-65 parts of aeolian sand, 30-40 parts of construction waste, and 5-10 parts of silicate cement as raw materials, and the total amount of aeolian sand, construction waste, and silicate cement is 100 parts.

[0010] S2, Mixing:

[0011] The raw materials are added to a mortar mixer and mixed evenly. Then, thickener, expanding agent, added water, water-reducing agent, and anti-permeability agent are added in sequence, and then mixed evenly again to obtain a mixture. The amount of thickener added is 0.1~0.6% of the total mass of the raw materials; the amount of expanding agent added is 0.5~4% of the total mass of the raw materials; the amount of water-reducing agent added is 0.2~0.8% of the total mass of the raw materials; the amount of anti-permeability agent added is 2~8% of the total mass of the raw materials; the amount of added water M is calculated by the following formula:

[0012]

[0013] in, M m represents the amount of water added, m represents the total mass of raw materials, and m1 represents the mass of aeolian sand. i 1 represents the moisture content of aeolian sand, and m2 represents the mass of construction waste. i 2 represents the moisture content of construction waste;

[0014] S3, Molding:

[0015] The mixture is pressed into shape under a pressure of 1-20 MPa to obtain aeolian sand solidified material. After curing the aeolian sand solidified material under natural conditions for 26-30 days, an impermeable cushion layer is obtained.

[0016] Description: This invention combines aeolian sand and construction waste, using cement as a binder and supplemented with some additives to prepare an impermeable cushion layer. Aeolian sand itself has very low clay content and is a non-frost-susceptible soil, effectively preventing frost heave. Construction waste contains more moisture, sticky particles, and active minerals, which can promote the bonding of the components and improve the impermeability of the cushion layer. Furthermore, both aeolian sand and construction waste are readily available materials in desert areas, which can effectively reduce transportation costs compared to traditional cement-clay materials.

[0017] Furthermore, the aeolian sand composition includes SiO2, Al2O3, CaO, Fe2O3 and MgO, wherein the content of SiO2 and Al2O3 accounts for 75-80% of the total mass of the aeolian sand.

[0018] Note: The aeolian sand with the above composition has good water stability. After wet pressing, its strength increases when the component dries and loses water, and its strength decreases very little when it is saturated with water, which can effectively ensure the structural strength of the building project.

[0019] Furthermore, the particle size of the construction waste is ≤5mm.

[0020] Note: Limiting the particle size of construction waste can reduce internal defects in the seepage-proof layer and ensure its structural strength.

[0021] Furthermore, the thickener comprises, by mass percentage: 10-20% starch ether and 80-90% cellulose ether.

[0022] Note: The thickeners in the above-mentioned components have good lubricity and rapid thickening ability, which can increase the viscosity of the mixture and improve its water retention.

[0023] Furthermore, the expanding agent is any one or more of magnesium oxide, calcium oxide, and anhydrous gypsum in any proportion.

[0024] Note: The expansion agent in the above-mentioned components can expand on its own or react with other components in the mixture to expand, which can compensate for the shrinkage of the impermeable layer and prevent it from cracking.

[0025] Furthermore, the water-reducing agent is any one or a mixture of polycarboxylate water-reducing agents, lignin sulfonate water-reducing agents, and melamine resin water-reducing agents in any proportion.

[0026] Note: The water-reducing agent with the above components can be directionally adsorbed onto the surface of cement particles, reducing the surface tension of water and the interfacial tension between water and cement particles, so that the cement particles can be better wetted.

[0027] Furthermore, the components of the antipermeability agent, by mass percentage, include: 85-90% water glass and 10-15% phosphate.

[0028] Note: The above-mentioned anti-seepage agent can react with the metal cations in the mixture to generate expansive crystals, which can block the capillary channels inside the anti-seepage layer, increasing its density and anti-seepage properties.

[0029] Further, in step S1, after weighing the aeolian sand, the aeolian sand is sieved to obtain coarse sand with a particle size > 0.15 mm and fine sand with a particle size ≤ 0.15 mm. The fine sand is then modified and mixed with the coarse sand.

[0030] The method for modifying the fine sand is as follows:

[0031] S1-1. Add phenolic resin to anhydrous ethanol and heat to 40-50℃ while stirring to obtain the first mixture; add fine sand to the modifier and ultrasonically disperse for 10-15 minutes to obtain the second mixture; the mass ratio of fine sand, phenolic resin, modifier and anhydrous ethanol is 12:3:32:10.

[0032] S1-2. Add a surfactant to the second mixture once, then heat the second mixture while continuously adding the first mixture during heating. Add the surfactant to the second mixture every 5-10°C increase in temperature until all of the first mixture has been added. Stop heating and stir for 15-30 minutes to obtain the third mixture. The initial amount of surfactant added is 3-5% of the mass of the fine sand. Subsequent additions of surfactant are 10-15% less than the previous addition. The heating rate of the second mixture is 2-4°C / min, and the amount of the first mixture added per minute is 4-6% of the total weight of the second mixture.

[0033] S1-3. After filtering the third mixture, a solid is obtained. The solid is then dried and dispersed by vibration to obtain modified fine sand.

[0034] Explanation: The above method screens aeolian sand and modifies only the fine sand, reducing production costs. At the same time, the surface of the fine sand is coated with a resin layer after modification, which improves the bonding between the fine sand and cement, reduces the porosity inside the seepage barrier, and improves the seepage resistance of the seepage barrier.

[0035] Furthermore, the modifier comprises, by mass percentage: 10-20% polyacrylic acid emulsion, 15-30% polyacrylamide, 6-10% sodium borohydride, and the remainder being deionized water.

[0036] Note: The modifiers in the above-mentioned components can improve the wettability of aeolian sand particles and enhance the bonding between aeolian sand particles during mixing, so that the coarse and fine sand in the seepage prevention layer can be better bonded together, thereby improving the strength of the seepage prevention layer.

[0037] Furthermore, the surfactant is any one or a mixture of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and potassium dodecyl sulfate in any proportion.

[0038] Note: The above-mentioned surfactant can improve the surface activity of aeolian sand particles, making the aeolian sand particles easier to wet, and enabling the components in the modifier to be evenly dispersed in the third mixture.

[0039] The beneficial effects of this invention are:

[0040] (1) This invention uses aeolian sand and construction waste in combination, with cement as the binding material and some additives to prepare an impermeable cushion layer. Aeolian sand itself has very little clay content and is a non-frost-susceptible soil, which can effectively prevent frost heave. Construction waste contains more water, sticky particles and active minerals, which can promote the bonding of the components and improve the impermeability of the impermeable cushion layer. Moreover, aeolian sand and construction waste are both existing materials in desert areas, which can effectively reduce transportation costs compared with traditional cement clay materials.

[0041] (2) The present invention reduces production costs by screening the aeolian sand and modifying only the fine sand. At the same time, the surface of the fine sand is coated with a resin layer after modification, which improves the bonding between the fine sand and cement, reduces the porosity inside the anti-seepage layer, and improves the anti-seepage performance of the anti-seepage layer. Detailed Implementation

[0042] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0043] Example 1: A method for preparing an impermeable cushion layer from solidified aeolian sand, comprising the following steps:

[0044] S1. Ingredients:

[0045] Weigh out 59 parts by weight of aeolian sand, 34 parts by weight of construction waste, and 7 parts by weight of silicate cement as raw materials, for a total of 100 parts of aeolian sand, construction waste, and silicate cement; wherein the aeolian sand comprises SiO2, Al2O3, CaO, Fe2O3, and MgO, with SiO2 and Al2O3 accounting for 78% of the total mass of the aeolian sand; the particle size of the construction waste is ≤5mm; and P.O42.5 cement is used as the silicate cement.

[0046] S2, Mixing:

[0047] The raw materials are added to a mortar mixer and mixed evenly. Then, thickener, expanding agent, added water, water-reducing agent, and anti-permeability agent are added in sequence, and then mixed evenly again to obtain a mixture. The amount of thickener added accounts for 0.3% of the total mass of the raw materials; the amount of expanding agent added accounts for 2% of the total mass of the raw materials; the amount of water-reducing agent added accounts for 0.6% of the total mass of the raw materials; the amount of anti-permeability agent added accounts for 6% of the total mass of the raw materials; the amount of added water M is calculated by the following formula:

[0048]

[0049] in, M m represents the amount of water added, m represents the total mass of raw materials, and m1 represents the mass of aeolian sand. i1 represents the moisture content of aeolian sand, and m2 represents the mass of construction waste. i 2 represents the moisture content of the construction waste. In this example, m1 is 590g, θ1 is 3%, m2 is 340g, θ2 is 12%, and m is 1000g. The calculated values ​​are as follows: M It weighs 21.5g;

[0050] The thickener comprises, by mass percentage: 15% starch ether and 85% cellulose ether, wherein the starch ether is carboxymethyl starch ether and the cellulose ether is hydroxypropyl methylcellulose; the expanding agent is calcium oxide; the water-reducing agent is polycarboxylate water-reducing agent; and the antipermeability agent comprises, by mass percentage: 87% water glass and 13% phosphate.

[0051] S3, Molding:

[0052] The mixture is pressed into shape under a pressure of 10 MPa to obtain aeolian sand solidified material. After curing the aeolian sand solidified material under natural conditions for 28 days, an impermeable cushion layer is obtained.

[0053] Example 2: This example is basically the same as Example 1, except that 55 parts of aeolian sand, 40 parts of construction waste, and 5 parts of silicate cement are weighed as raw materials.

[0054] Example 3: This example is basically the same as Example 1, except that 65 parts of aeolian sand, 30 parts of construction waste, and 5 parts of silicate cement are weighed as raw materials.

[0055] Example 4: This example is basically the same as Example 1, except that the amount of thickener added accounts for 0.1% of the total mass of raw materials; the amount of expansion agent added accounts for 0.5% of the total mass of raw materials; the amount of water-reducing agent added accounts for 0.2% of the total mass of raw materials; and the amount of anti-permeability agent added accounts for 2% of the total mass of raw materials.

[0056] Example 5: This example is basically the same as Example 1, except that the amount of thickener added accounts for 0.1~0.6% of the total mass of raw materials; the amount of expansion agent added accounts for 4% of the total mass of raw materials; the amount of water-reducing agent added accounts for 0.08% of the total mass of raw materials; and the amount of anti-permeability agent added accounts for 8% of the total mass of raw materials.

[0057] Example 6: This example is basically the same as Example 1, except that the thickener comprises, by mass percentage: 10% starch ether and 90% cellulose ether.

[0058] Example 7: This example is basically the same as Example 1, except that the thickener comprises, by mass percentage: 20% starch ether and 80% cellulose ether.

[0059] Example 8: This example is basically the same as Example 1, except that the components of the antipermeability agent include, by mass percentage: 85% water glass and 15% phosphate.

[0060] Example 9: This example is basically the same as Example 1, except that the components of the antipermeability agent include, by mass percentage: 90% water glass and 10% phosphate.

[0061] Example 10: This example is basically the same as Example 1, except that after weighing the aeolian sand, the aeolian sand is sieved to obtain coarse sand with a particle size > 0.15 mm and fine sand with a particle size ≤ 0.15 mm. The fine sand is then modified and mixed with the coarse sand.

[0062] The method for modifying the fine sand is as follows:

[0063] S1-1. Phenolic resin is added to anhydrous ethanol and heated to 45°C under stirring to obtain a first mixture; fine sand is added to the modifier and ultrasonically dispersed for 12 minutes to obtain a second mixture; the mass ratio of fine sand, phenolic resin, modifier, and anhydrous ethanol is 12:3:32:10; wherein, the modifier comprises, by mass percentage: 15% polyacrylic acid emulsion, 25% polyacrylamide, 8% sodium borohydride, and the remainder is deionized water;

[0064] S1-2. Add a surfactant to the second mixture once, then heat the second mixture while continuously adding the first mixture during the heating process. For every 8°C increase in temperature of the second mixture, add a surfactant once, until all of the first mixture has been added. Stop heating and stir for 15-30 minutes to obtain the third mixture. The initial amount of surfactant added is 4% of the mass of the fine sand. Subsequent additions of surfactant are 12% less than the previous addition. The heating rate of the second mixture is 3°C / min, and the amount of the first mixture added per minute is 5% of the total weight of the second mixture. The surfactant is sodium dodecylbenzenesulfonate.

[0065] S1-3. After filtering the third mixture, a solid is obtained. The solid is then dried and dispersed by vibration to obtain modified fine sand.

[0066] Example 11: This example is basically the same as Example 1, except that a surfactant is added to the second mixture every time the temperature of the second mixture increases by 5°C, and the heating rate of the second mixture is 2°C / min.

[0067] Example 12: This example is basically the same as Example 1, except that a surfactant is added to the second mixture once for every 10°C increase in temperature, and the heating rate of the second mixture is 4°C / min.

[0068] Example 13: This example is basically the same as Example 1, except that the amount of surfactant added initially accounts for 3% of the mass of fine sand, and the amount of surfactant added each time thereafter is reduced by 10% compared to the previous one.

[0069] Example 14: This example is basically the same as Example 1, except that the amount of surfactant added initially accounts for 5% of the mass of fine sand, and the amount of surfactant added each time thereafter is reduced by 15% compared to the previous one.

[0070] Example 15: This example is basically the same as Example 1, except that the amount of the first mixture added per minute is 4% of the total weight of the second mixture.

[0071] Example 16: This example is basically the same as Example 1, except that the amount of the first mixture added per minute is 6% of the total weight of the second mixture.

[0072] Example 17: This example is basically the same as Example 1, except that the modifier components, by mass percentage, include: 10% polyacrylic acid emulsion, 15% polyacrylamide, 6% sodium borohydride, and the remainder is deionized water.

[0073] Example 18: This example is basically the same as Example 1, except that the modifier consists of the following components by mass percentage: 20% polyacrylic acid emulsion, 30% polyacrylamide, 10% sodium borohydride, and the remainder is deionized water.

[0074] Experimental example:

[0075] Samples were taken from the geomembranes prepared in each embodiment, and performance tests were conducted on each sample to investigate the influence of various parameters on the performance of the geomembranes. The specific investigation is as follows:

[0076] 1. Investigate the influence of raw material ratio on the performance of the impermeable liner.

[0077] Using Examples 1, 2, and 3 as experimental comparisons, the performance of the impermeable liner under different raw material ratios is shown in Table 1 below:

[0078] Table 1 Performance of seepage-proof underlayment with different raw material ratios

[0079]

[0080] As shown in Table 1, the geomembrane in Example 1 has the highest unconfined compressive strength and the lowest permeability coefficient, indicating that the geomembrane in Example 1 has the highest strength and the best impermeability performance, and the raw material ratio selected in Example 1 is the best.

[0081] 2. Investigate the effect of the amount of admixture added on the performance of the impermeable layer.

[0082] Using Examples 1, 4, and 5 as experimental comparisons, the performance of the impermeable liner under different amounts of admixtures is shown in Table 2 below:

[0083] Table 2 Performance of the seepage-proof underlayment with different amounts of admixtures.

[0084]

[0085] As shown in Table 2, the geomembrane of Example 1 has the highest unconfined compressive strength and the lowest permeability coefficient, indicating that the geomembrane of Example 1 has the highest strength and the best anti-seepage performance, and the amount of admixture added in Example 1 is optimal.

[0086] 3. Investigate the effect of thickener ratio on the performance of the impermeable layer.

[0087] Using Examples 1, 6, and 7 as experimental comparisons, the performance of the impermeable liner under different thickener ratios is shown in Table 3 below:

[0088] Table 3 Performance of the seepage-proof underlayment with different thickener ratios.

[0089]

[0090] As shown in Table 3, the geomembrane of Example 1 has the highest unconfined compressive strength and the lowest permeability coefficient, indicating that the geomembrane of Example 1 has the highest strength and the best anti-seepage performance, and the thickener ratio selected in Example 1 is the best.

[0091] 4. Investigate the effect of the anti-seepage agent ratio on the performance of the anti-seepage layer.

[0092] Using Examples 1, 8, and 9 as comparative experiments, the performance of the impermeable liner under different ratios of the anti-permeability agent is shown in Table 4 below:

[0093] Table 4 Performance of seepage-proofing layers with different ratios of anti-seepage agent

[0094]

[0095] As shown in Table 4, the geomembrane of Example 1 has the highest unconfined compressive strength and the lowest permeability coefficient, indicating that the geomembrane of Example 1 has the highest strength and the best anti-seepage performance, and the anti-seepage agent ratio selected in Example 1 is the best.

[0096] 5. Investigate the impact of modification treatment on the performance of the impermeable layer.

[0097] Using Examples 1 and 10 as experimental comparisons, and with Example 10 as a reference, coarse sand was also modified as Comparative Example 1. The performance of the impermeable liner under different modification treatments is shown in Table 5 below:

[0098] Table 5 Performance of the seepage-proof under different modification treatments

[0099]

[0100] As shown in Table 5, compared with Examples 1 and 10, Example 10 has a higher unconfined compressive strength and a smaller permeability coefficient, indicating that the strength and impermeability of the geomembrane have been improved after the modification treatment of Example 10. Compared with Comparative Example 1, the performance of Example 10 is not much different. From the perspective of production cost, the modification treatment method of Example 10 is better.

[0101] 6. Investigate the effect of the heating parameters of the second mixture on the performance of the impermeable layer.

[0102] Using Examples 10, 11, and 12 as comparative experiments, the performance of the impermeable liner under different heating parameters of the second mixture is shown in Table 6 below:

[0103] Table 6 Performance of the seepage-proofing layer under different heating parameters of the second mixture.

[0104]

[0105] As shown in Table 6, the geomembrane of Example 10 has the highest unconfined compressive strength and the lowest permeability coefficient, indicating that the geomembrane of Example 10 has the highest strength and the best anti-seepage performance, and the second mixed liquor heating parameters selected in Example 10 are the best.

[0106] 7. Investigate the effect of surfactant dosage on the performance of the geomembrane.

[0107] Using Examples 10, 13, and 14 as comparative experiments, and Example 10 as a reference, the amount of surfactant added was fixed at 4% of the mass of fine sand as Comparative Example 2. The performance of the geotextile under different amounts of surfactant added is shown in Table 7 below:

[0108] Table 7 Performance of the seepage-proofing layer under different surfactant addition amounts

[0109]

[0110] As shown in Table 7, compared with Examples 10, 13, and 14, the geomembrane of Example 10 has the highest unconfined compressive strength and the lowest permeability coefficient, indicating that the geomembrane of Example 10 has the highest strength and the best anti-seepage performance, and the amount of surfactant added in Example 10 is optimal. Compared with Comparative Example 2, the geomembrane of Example 10 has higher unconfined compressive strength and a smaller permeability coefficient, indicating that the surfactant addition method selected in Example 10 is better.

[0111] 8. Investigate the effect of the first mixture addition rate on the performance of the impermeable layer.

[0112] Using Examples 10, 15, and 16 as comparative experiments, the performance of the impermeable liner at different addition rates of the first mixture is shown in Table 8 below:

[0113] Table 8 Performance of the anti-seepage layer under different addition rates of the first mixture.

[0114]

[0115] As shown in Table 8, the geomembrane of Example 10 has the highest unconfined compressive strength and the lowest permeability coefficient, indicating that the geomembrane of Example 10 has the highest strength and the best anti-seepage performance, and the addition rate selected in Example 10 is the optimal.

[0116] 9. Investigate the influence of modifier composition on the performance of the geomembrane.

[0117] Using Examples 10, 17, and 18 as experimental comparisons, the performance of the geomembrane under different modifier compositions is shown in Table 9 below:

[0118] Table 9. Performance of the seepage-proof underlayment with different modifier compositions.

[0119]

[0120] As shown in Table 9, the geomembrane of Example 10 has the highest unconfined compressive strength and the lowest permeability coefficient, indicating that the geomembrane of Example 10 has the highest strength and the best anti-seepage performance, and the modifier component selected in Example 10 is the best.

Claims

1. A method for preparing an impermeable cushion layer from solidified aeolian sand, characterized in that, Includes the following steps: S1. Ingredients: Weigh out 55-65 parts of aeolian sand, 30-40 parts of construction waste, and 5-10 parts of silicate cement as raw materials, for a total of 100 parts of aeolian sand, construction waste, and silicate cement. S2, Mixing: The raw materials are added to a mortar mixer and mixed evenly. Then, thickener, expanding agent, added water, water-reducing agent, and anti-permeability agent are added in sequence, and then mixed evenly again to obtain a mixture. The amount of thickener added is 0.1~0.6% of the total mass of the raw materials; the amount of expanding agent added is 0.5~4% of the total mass of the raw materials; the amount of water-reducing agent added is 0.2~0.8% of the total mass of the raw materials; the amount of anti-permeability agent added is 2~8% of the total mass of the raw materials; the amount of added water M is calculated by the following formula: in, M m represents the amount of water added, m represents the total mass of raw materials, and m1 represents the mass of aeolian sand. θ 1 represents the moisture content of aeolian sand, and m2 represents the mass of construction waste. θ 2 represents the moisture content of construction waste; S3, Molding: The mixture is pressed into shape under a pressure of 1-20MPa to obtain aeolian sand solidified material. After curing the aeolian sand solidified material under natural conditions for 26-30 days, an impermeable cushion layer is obtained. In step S1, after weighing the aeolian sand, the aeolian sand is sieved to obtain coarse sand with a particle size > 0.15 mm and fine sand with a particle size ≤ 0.15 mm. The fine sand is then modified and mixed with the coarse sand. The method for modifying the fine sand is as follows: S1-1. Add phenolic resin to anhydrous ethanol and heat to 40-50℃ while stirring to obtain the first mixture; add fine sand to the modifier and ultrasonically disperse for 10-15 minutes to obtain the second mixture; the mass ratio of fine sand, phenolic resin, modifier and anhydrous ethanol is 12:3:32:

10. The modifier comprises, by mass percentage: 10-20% polyacrylic acid emulsion, 15-30% polyacrylamide, 6-10% sodium borohydride, and the remainder being deionized water. S1-2. Add a surfactant to the second mixture once, then heat the second mixture while continuously adding the first mixture during heating. Add the surfactant to the second mixture every 5-10°C increase in temperature until all of the first mixture has been added. Stop heating and stir for 15-30 minutes to obtain the third mixture. The initial amount of surfactant added is 3-5% of the mass of the fine sand. Subsequent additions of surfactant are 10-15% less than the previous addition. The heating rate of the second mixture is 2-4°C / min, and the amount of the first mixture added per minute is 4-6% of the total weight of the second mixture. S1-3. After filtering the third mixture, a solid is obtained. The solid is then dried and dispersed by vibration to obtain modified fine sand.

2. The method for preparing an impermeable cushion layer from solidified aeolian sand according to claim 1, characterized in that, The aeolian sand composition includes SiO2, Al2O3, CaO, Fe2O3 and MgO, wherein the content of SiO2 and Al2O3 accounts for 75-80% of the total mass of the aeolian sand.

3. The method for preparing an impermeable cushion layer from solidified aeolian sand according to claim 1, characterized in that, The particle size of the construction waste is ≤5mm.

4. The method for preparing an impermeable cushion layer from solidified aeolian sand according to claim 1, characterized in that, The thickener comprises, by mass percentage: 10-20% starch ether and 80-90% cellulose ether.

5. The method for preparing an impermeable cushion layer from solidified aeolian sand according to claim 1, characterized in that, The expanding agent is any one or more of magnesium oxide, calcium oxide, and anhydrous gypsum in any proportion.

6. The method for preparing an impermeable cushion layer from solidified aeolian sand according to claim 1, characterized in that, The water-reducing agent is any one or more of polycarboxylate water-reducing agents, lignin sulfonate water-reducing agents, and melamine resin water-reducing agents, mixed in any proportion.

7. The method for preparing an impermeable cushion layer from solidified aeolian sand according to claim 1, characterized in that, The components of the antipermeability agent, by mass percentage, include: 85-90% water glass and 10-15% phosphate.

8. The method for preparing an impermeable cushion layer from solidified aeolian sand according to claim 1, characterized in that, The surfactant is any one or a mixture of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and potassium dodecyl sulfate in any proportion.

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