Durable solid waste-based foam light soil and method of making same

Abstract

The application provides a durable solid waste-based foam light soil and a preparation method thereof, and comprises the following raw materials in parts by weight: 25-30 parts of alkaline solid waste, 30-40 parts of silico-aluminous solid waste, 5-10 parts of sulfate solid waste, 0.1-0.3 parts of water reducing agent, 0.3-0.5 parts of composite foaming agent, 0.5-1.5 parts of expanding agent, 0.5-1.5 parts of anti-cracking fiber, 2-3 parts of anti-freezing agent, and 35-60 parts of water. The composite foaming agent is a compound of alkyl sulfonate and polymeric sulfonate at a mass ratio of 1:0.3-0.5. The polymeric sulfonate is prepared by copolymerization of an olefin sulfonate monomer and an unsaturated benzyl tertiary amine monomer at a mass ratio of 5-8:3. The polymeric sulfonate can not only form a tough and unbreakable bubble liquid film, but also help to complex calcium ions due to the tertiary amine group on the side group, so as to improve the calcium ion concentration around the foam, form a dense and solid pore wall, and improve the bearing capacity of the pore wall to the frost heaving pressure.

Description

Technical Field

[0001] This invention belongs to the technical field of the construction industry, specifically relating to a durable solid waste-based foamed lightweight soil and its preparation method. Background Technology

[0002] The accumulation of large amounts of solid waste leads to the waste of resources and environmental pollution, making the comprehensive utilization of solid waste an urgent matter.

[0003] Foamed lightweight materials, as a new type of building material, are widely used in road engineering due to their excellent properties such as porosity, lightweight, adjustable density and strength, convenient construction, and self-supporting ability after hardening. These properties can reduce additional stress on the foundation and prevent problems such as settlement and cracking. Using solid waste to replace cement in the preparation of foamed lightweight soil not only solves the waste and environmental problems caused by solid waste accumulation, but also reduces cement usage and lowers project costs. For example, patent CN111116117B discloses a chemically activated sulfur-fixing ash-based foamed lightweight soil, which, by mass, is made from the following raw materials: 88-165 parts sulfur-fixing ash, 260-293 parts cement, 29-55 parts fly ash, 0.4-0.5 parts activator, 0.7-0.8 parts foaming agent, and 180-190 parts water. Patent CN112062532B discloses a red mud-based foamed lightweight soil, its preparation method, and its application. This red mud-based foamed lightweight soil comprises the following preparation components in parts by weight: 300-360 parts red mud, 40-80 parts cement, 90-140 parts activator, 10-30 parts foam, and 250-350 parts water. The activator is selected from at least one of gypsum, quicklime, alkali metal silicates, alkali metal sulfates, alkali metal carbonates, alkali metal hydroxides, alkali metal alkyl sulfonates, alkali metal alkylbenzene sulfonates, and alkali metal alkyl sulfates.

[0004] However, due to the complex composition of solid waste, although porous lightweight foamed soil with a certain density and strength can be produced by adjusting the relative amount of solid waste and other components, it has the problem of poor durability. That is, when encountering harsh or complex and changeable environments, the foamed lightweight soil prepared from solid waste has poor adaptability. Therefore, it is urgent to improve the durability of solid waste-based foamed lightweight soil. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a durable solid waste-based foamed lightweight soil and its preparation method. An anionic surfactant with tertiary amines on its side groups is prepared by polymerization between an alkenyl sulfonate monomer and an unsaturated phenyl tertiary amine monomer. Using this surfactant as a foaming agent not only forms a tough, uncrackable bubble film, but also, due to the tertiary amine groups on its side groups facilitating the complexation of calcium ions, increases the calcium ion concentration around the foam, forming dense and solid pore walls and improving the pore walls' ability to withstand frost heave pressure.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A durable solid waste-based foamed lightweight soil comprises the following raw materials in parts by weight: 25-30 parts alkaline solid waste, 30-40 parts silica-alumina solid waste, 5-10 parts sulfate solid waste, 0.1-0.3 parts water-reducing agent, 0.3-0.5 parts composite foaming agent, 0.5-1.5 parts expanding agent, 0.5-1.5 parts crack-resistant fiber, 2-3 parts antifreeze agent, and 35-60 parts water. The composite foaming agent is a mixture of alkyl sulfonate and polysulfonate in a mass ratio of 1:0.3-0.5. The polysulfonate is copolymerized by copolymerizing an alkenyl sulfonate monomer and an unsaturated phenyl tertiary amine monomer in a mass ratio of 5-8:3.

[0008] The ratio of alkenyl sulfonate monomers to unsaturated phenyl tertiary amine monomers should be controlled within a certain range. Too high a ratio is not conducive to improving the density and durability of the pore walls; too low a ratio will lead to excessive complexation of calcium ions by tertiary amines, causing excessive slow setting of foamed lightweight soil, low early strength, difficulty in molding, and even mold collapse. Therefore, the ratio of the two needs to be strictly controlled.

[0009] The unsaturated phenyl tertiary amine monomer is prepared by reacting unsaturated phenol, formaldehyde, and secondary amine in a molar ratio of 1:1.40-1.50:1.55-1.70.

[0010] The unsaturated phenol is selected from one or a combination of two or more of 4-vinylphenol, 3-vinylphenol, 2-vinylphenol, 4-allylphenol, 3-allylphenol, 2-allylphenol, 2-(allyloxy)phenol, and 4-allyloxyphenol, and the secondary amine is selected from one or a combination of two or more of dimethylamine, methyl ethylamine, and diethylamine.

[0011] The alkenyl sulfonate monomer is selected from one or a combination of two or more of sodium p-styrene sulfonate, sodium methpropylene sulfonate, sodium allyl sulfonate, and sodium vinyl sulfonate.

[0012] The polymeric sulfonate is prepared by a method comprising the following steps:

[0013] 2) Under an inert atmosphere, in a reaction apparatus equipped with a stirrer and a reflux condenser, unsaturated phenol and ethanol are added and mixed evenly. Formaldehyde solution is added dropwise under controlled temperature. After the addition is complete, the temperature is raised to carry out the reaction. After cooling, a secondary amine is added and the temperature is raised again to carry out the reaction. The mixture is then distilled, cooled to crystallize, washed, and dried to obtain an unsaturated phenyl tertiary amine monomer for later use.

[0014] 2) Add organic solvent and emulsifier to the reaction vessel and stir to disperse into an oil phase. Mix the unsaturated phenyl tertiary amine monomer, alkenyl sulfonate monomer, oxidant, azo initiator, molecular weight regulator and water in step 1) to form an aqueous phase. Add the aqueous phase to the reaction vessel and stir with the oil phase to form a water-in-oil emulsion. Purge with inert gas, heat up, stop purging, add reducing agent to carry out the reaction. After the reaction is completed, cool to room temperature, distill under reduced pressure, filter and dry to obtain polysulfonate.

[0015] Step 1) The concentration of the formaldehyde solution is 13-14.5 mol / L. The temperature control is maintained at 20-35℃. The dropping time is 20-60 min. The heating is raised to 60-80℃ and the reaction time is 1-2 h. The cooling is cooled to 20-35℃. After adding dimethylamine, the temperature is raised again to 70-80℃ and the reaction time is 1-3 h. The distillation is used to remove water, solvent and unreacted raw materials. The washing is done with petroleum ether 1-3 times. The drying is done under vacuum at 0.01-0.1 MPa and 60-100℃ for 10-24 h.

[0016] Further, in step 2), the unsaturated phenyl tertiary amine monomer and the alkenyl sulfonate monomer in the aqueous phase constitute 35-45 wt% of the aqueous phase. The oxidant is selected from one or a combination of two or more of ammonium persulfate, potassium persulfate, and sodium persulfate. The reducing agent is selected from one or a combination of two or more of sodium sulfite, sodium bisulfite, sodium metabisulfite, sodium thiosulfate, sodium dithionite, ferrous chloride, ferrous sulfate, cuprous chloride, triethylamine, triethanolamine, and tetramethylethylenediamine. The azo initiator is one or a combination of two or more of azobisisopropylimidazoline hydrochloride, azobisisobutylamidine hydrochloride, and azobisisobutyronitrile. The mass ratio of the oxidant to the reductant is 1:2 to 2:1. The total mass of the oxidant and the reductant accounts for 0.01-0.3 wt% of the total mass of the unsaturated phenyl tertiary amine monomer and the alkenyl sulfonate monomer. The initiator accounts for 0.8-1.2 wt% of the total mass of the unsaturated phenyl tertiary amine monomer and the alkenyl sulfonate monomer.

[0017] Further, in step 2), the emulsifier is selected from one or more combinations of Span60, Tween80, and OP-10, and the amount of the emulsifier is 1-1.5 wt% of the water-in-oil emulsion. The molecular weight regulator is selected from one or more combinations of C1-C4 lower fatty alcohols, thiols, formates, sodium methyl allyl sulfonate, and urea, and the molecular weight regulator accounts for 1-2 wt% of the water-in-oil emulsion. The mass ratio of the oil phase to the water phase is 3-4:6-7. The mass of the unsaturated phenyl tertiary amine monomer and the alkenyl sulfonate monomer accounts for 30-40 wt% of the water-in-oil emulsion. The organic solvent is selected from one or more combinations of cyclohexane, No. 10 machine oil, and kerosene. The temperature is raised to 40-60°C. The inert gas venting time is 0.5-1.5 h. The reaction time is 3-5 h.

[0018] The alkyl sulfonate is selected from one or a combination of two or more of sodium dodecyl sulfonate, sodium hexadecyl sulfonate, and sodium petroleum sulfonate.

[0019] The alkaline solid waste is selected from one or more of red mud, steel slag, and alkali slag, and the median D50 particle size of the alkaline solid waste is 1-10 μm.

[0020] Furthermore, the Na2O content of the red mud is 10-20 wt%.

[0021] Furthermore, the CaO content of the steel slag is 30-45 wt%.

[0022] Furthermore, the CaO content of the alkali residue is 35-45 wt%.

[0023] The silicon-aluminate solid waste is selected from one or more combinations of fly ash and blast furnace slag. The median D50 particle size of the silicon-aluminate solid waste is 1-10 μm, the silicon dioxide content is 30-55 wt%, and the aluminum oxide content is 10-25 wt%.

[0024] The sulfate solid waste is selected from one or a combination of two or more of desulfurized gypsum, phosphogypsum, electrolytic manganese slag, and titanium gypsum. The median D50 particle size of the sulfate solid waste is 1-10 μm, and the SO3 content is 35-50 wt%.

[0025] The water-reducing agent is selected from one or a combination of two types of polycarboxylate water-reducing agents and naphthalene-based water-reducing agents.

[0026] The expanding agent is selected from one or a combination of magnesium oxide and calcium sulfoaluminate.

[0027] The crack-resistant fiber is selected from one or a combination of two or more of the following: polyolefin fiber, polyester fiber, mineral wool fiber, and metal fiber.

[0028] The organic antifreeze agent is selected from one or a combination of two or more of glycerol, triethanolamine, glucose, urea, and ethylene glycol.

[0029] The present invention also provides a method for preparing the above-mentioned durable solid waste-based foamed lightweight soil, comprising the following steps:

[0030] S1 mixes the composite foaming agent with water to produce foam for later use;

[0031] S2 mixes alkaline solid waste, siliceous aluminum solid waste, sulfate solid waste, water-reducing agent, expansion agent, crack-resistant fiber, antifreeze agent, and water evenly to obtain a mixture for later use;

[0032] S3 mixes the mixture with foam evenly, then pours and solidifies it to obtain durable solid waste-based foamed lightweight soil.

[0033] In step S1, the mass ratio of the composite foaming agent to water is 1:50-60. The foam production involves adding the mixture of composite foaming agent and water to a foaming machine with a foaming pressure of 0.3-0.5 MPa, compressing it to produce a density of 40-60 kg / m³. 3 The foam.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] An anionic surfactant with tertiary amines on its side groups was prepared by polymerization of an alkenyl sulfonate monomer and an unsaturated phenyl tertiary amine monomer. This foaming agent can not only form a tough and shatter-resistant bubble liquid film, but also increase the calcium ion concentration around the foam due to the tertiary amine groups on its side groups helping to complex calcium ions. This can form a dense and solid pore wall and improve the pore wall's ability to withstand frost heave pressure. Attached Figure Description

[0036] Figure 1 The solid waste-based foamed lightweight soil prepared in Example 1. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, all "parts" mentioned in the embodiments of the present invention are parts by weight. All reagents used are commercially available in the art.

[0038] The polycarboxylate superplasticizer was purchased from BASF, brand name RHEOPLUS 411.

[0039] Bayer red mud, blast furnace slag, and desulfurization gypsum were all purchased from Hebei Wenfeng Industrial Group Co., Ltd.

[0040] The median particle size of Bayer process red mud D50 is 1.5 μm, and the Na2O content is 11.9 wt%.

[0041] The median particle size of D50 blast furnace slag is 4.6 μm, the silica content is 31.4 wt%, and the alumina content is 13.5 wt%.

[0042] The median particle size of the desulfurized gypsum D50 is 3.7 μm, and the SO3 content is 48.5 wt%.

[0043] The polypropylene fiber was purchased from Sichuan Jiabanghui New Material Technology Co., Ltd., with a linear density of 15 dtex and a length of 15 mm.

[0044] Preparation of durable solid waste-based foamed lightweight soil

[0045] Example 1

[0046] 1) Under a nitrogen atmosphere, in a reaction apparatus equipped with a stirrer and a reflux condenser, 0.1 mol of 3-vinylphenol and 30 mL of ethanol were added and mixed thoroughly. 11.5 mL of a 13 mol / L formaldehyde solution (water as solvent) was added dropwise under controlled temperature. After the addition was completed in 30 min, the temperature was raised to 60 °C and reacted for 2 h. After cooling, 0.17 mol of dimethylamine was added, and the temperature was raised again to 80 °C and reacted for 3 h. The solvent and unreacted raw materials were removed by distillation. The mixture was allowed to cool naturally to room temperature and crystallized. The solid obtained by crystallization was washed three times with petroleum ether and dried at 80 °C under a vacuum of 0.05 MPa for 12 h to obtain an unsaturated phenyl tertiary amine monomer for later use.

[0047] The reaction formula is as follows:

[0048]

[0049] 2) Add 100g of cyclohexane, 3.33g of Span60 and Tween80 in a mass ratio of 8:1 to the reaction vessel and stir to disperse into an oil phase. Add 30g of the unsaturated phenyl tertiary amine monomer from step 1), 50g of sodium allyl sulfonate, 0.04g of ammonium persulfate as oxidant, 0.64g of azobisisobutyronitrile, 3.33g of urea as a molecular weight regulator, and 119.32g of water to the aqueous phase, stir to form a water-in-oil emulsion with a mass ratio of oil to water of 4:6. Purge with nitrogen and heat to 60°C. After 1 hour of purging, stop purging and add 0.04g of sodium bisulfite as a reducing agent to react for 4 hours. After the reaction is complete, cool to room temperature, distill under reduced pressure, filter, and dry to obtain the polysulfonate.

[0050]

[0051] 3) Mix 50g of the composite foaming agent with 2500g of water. The composite foaming agent is a mixture of sodium dodecyl sulfonate and the polymeric sulfonate obtained in step 2) at a mass ratio of 1:0.5. Add the mixture to a foaming machine with a foaming pressure of 0.4MPa to obtain foam with a density of 55kg / m³.3 Prepare the foam for later use;

[0052] 4) Mix 3000g of alkaline solid waste red mud, 4000g of siliceous aluminum solid waste blast furnace slag, 1000g of sulfate solid waste desulfurization gypsum, 30g of water-reducing agent RHEOPLUS 411, 100g of expansion agent magnesium oxide, 100g of polypropylene fiber, 200g of triethanolamine, and 2300g of water evenly to obtain a mixture for later use.

[0053] 5) Mix the mixture obtained in step 4) with the foam obtained in step 3) evenly, and then pour it into a 100mm×100mm×100mm triple cubic mold. Place the mold in a standard curing chamber (curing conditions: temperature 20±1℃, relative humidity 95±1%) and cure for 24 hours. After demolding, the demolded test block continues to be cured in the standard curing chamber for 28 days to obtain durable solid waste-based foamed lightweight soil.

[0054] Example 2

[0055] The rest is the same as in Example 1, except that the amount of sodium allyl sulfonate used in step 2) is 80g.

[0056] Example 3

[0057] The rest is the same as in Example 1, except that the amount of sodium allyl sulfonate used in step 2) is 90g.

[0058] Example 4

[0059] The rest is the same as in Example 1, except that the amount of sodium allyl sulfonate used in step 2) is 40g.

[0060] Example 5

[0061] The rest is the same as in Example 1, except that the amount of triethanolamine used in step 4) is 300g.

[0062] Example 6

[0063] The rest is the same as in Example 1, except that the amount of composite foaming agent used in step 3) is 30g.

[0064] Example 7

[0065] The rest is the same as in Example 1, except that 50g of the composite foaming agent is compounded from sodium dodecyl sulfonate and the polymeric sulfonate obtained in step 2) at a mass ratio of 1:0.3.

[0066] Example 8

[0067] The rest is the same as in Example 1, except that in step 1), under a nitrogen atmosphere, in a reaction apparatus equipped with a stirrer and a reflux condenser, 0.1 mol of 3-vinylphenol and 30 mL of ethanol are added and mixed evenly. 10.7 mL of formaldehyde solution with a concentration of 13 mol / L (solvent is water) is added dropwise under controlled temperature. After the addition is completed in 30 min, the temperature is raised to 60 °C and reacted for 2 h. After cooling, 0.155 mol of dimethylamine is added and the temperature is raised again to react. The solvent and unreacted raw materials are removed by distillation. The mixture is naturally cooled to 20 °C to crystallize. The crystals are washed three times with petroleum ether and dried at 100 °C under a vacuum of 0.05 MPa for 12 h to obtain an unsaturated phenyl tertiary amine monomer for later use.

[0068] Example 9

[0069] The rest is the same as in Example 1, except that sodium p-styrene sulfonate is used instead of sodium allyl sulfonate in equal mass.

[0070] Example 10

[0071] The rest is the same as in Example 1, except that triethanolamine is replaced with an equal mass of glycerol.

[0072] Example 11

[0073] The rest is the same as in Example 1, except that in step 4), 3000g of alkaline solid waste red mud, 3000g of silicoaluminous solid waste blast furnace slag, 500g of sulfate solid waste desulfurization gypsum, 10g of water-reducing agent RHEOPLUS 411, 50g of expansion agent magnesium oxide, 100g of polypropylene fiber, 200g of triethanolamine, and 1400g of water are mixed evenly to obtain a mixture for later use.

[0074] Comparative Example 1

[0075] The rest is the same as in Example 1, except that the foaming agent is sodium dodecyl sulfonate throughout.

[0076] The lightweight foamed soil prepared in the above embodiments and comparative examples was subjected to the following performance tests:

[0077] Compressive strength: The sample size is 100mm×100mm×100mm. According to the standard GB / T 11969-2020 Test Method for Performance of Autoclaved Aerated Concrete, the unconfined compressive strength of foamed lightweight soil cured for 3 days and 28 days was tested at a rate of 2.0kN / s using a universal testing machine.

[0078] Freeze-thaw durability test: Refer to the standard GB / T 11969-2020 Test Method for Performance of Autoclaved Aerated Concrete. Stop the test when the mass loss of the foamed lightweight soil is 5wt%. Record the number of cycles and the unconfined compressive strength before and after the test cycles, and calculate the loss rate.

[0079] Table 1 Performance Test Results

[0080]

[0081] As shown in Table 1, the foamed lightweight soil prepared by this invention exhibits good freeze-thaw resistance and durability. Examples 1 and 10, and Comparative Example 1, demonstrate that the composite foaming agent has a significant synergistic effect with triethanolamine in improving durability.

[0082] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A durable solid waste-based foamed lightweight soil, characterized in that, The raw materials include the following parts by weight: 25-30 parts alkaline solid waste, 30-40 parts silicoaluminous solid waste, 5-10 parts sulfate solid waste, 0.1-0.3 parts water-reducing agent, 0.3-0.5 parts composite foaming agent, 0.5-1.5 parts expanding agent, 0.5-1.5 parts anti-cracking fiber, 2-3 parts antifreeze agent, and 35-60 parts water. The composite foaming agent is a mixture of alkyl sulfonate and polysulfonate at a mass ratio of 1:0.3-0.

5. The polysulfonate is copolymerized by copolymerizing alkenyl sulfonate monomer and unsaturated phenyl tertiary amine monomer at a mass ratio of 5-8:

3.

2. The durable solid waste-based foamed lightweight soil according to claim 1, characterized in that, The unsaturated phenyl tertiary amine monomer is prepared by reacting unsaturated phenol, formaldehyde, and secondary amine, with a molar ratio of 1:1.40-1.50:1.55-1.70; the alkenyl sulfonate monomer is selected from one or more combinations of sodium p-styrene sulfonate, sodium methpropylene sulfonate, sodium allyl sulfonate, and sodium vinyl sulfonate.

3. The durable solid waste-based foamed lightweight soil according to claim 2, characterized in that, The unsaturated phenol is selected from one or more of 4-vinylphenol, 3-vinylphenol, 2-vinylphenol, 4-allylphenol, 3-allylphenol, 2-allylphenol, 2-(allyloxy)phenol, and 4-allyloxyphenol, and the secondary amine is selected from one or more of dimethylamine, methyl ethylamine, and diethylamine.

4. The durable solid waste-based foamed lightweight soil according to claim 1, characterized in that, The polymeric sulfonate is prepared by a method comprising the following steps: 1) Under an inert atmosphere, in a reaction apparatus equipped with a stirrer and a reflux condenser, unsaturated phenol and ethanol are added and mixed evenly. Formaldehyde solution is added dropwise under controlled temperature. After the addition is complete, the temperature is raised to carry out the reaction. After cooling, a secondary amine is added and the temperature is raised again to carry out the reaction. The mixture is then distilled, cooled to crystallize, washed, and dried to obtain an unsaturated phenyl tertiary amine monomer for later use. 2) Add organic solvent and emulsifier to the reaction vessel and stir to disperse into an oil phase. Mix the unsaturated phenyl tertiary amine monomer, alkenyl sulfonate monomer, oxidant, azo initiator, molecular weight regulator and water in step 1) to form an aqueous phase. Add the aqueous phase to the reaction vessel and stir with the oil phase to form a water-in-oil emulsion. Purge with inert gas, heat up, stop purging, add reducing agent to carry out the reaction. After the reaction is completed, cool to room temperature, distill under reduced pressure, filter and dry to obtain polysulfonate.

5. The durable solid waste-based foamed lightweight soil according to claim 4, characterized in that, Step 1) The temperature control is to control the temperature at 20-35℃, the dropping time is 20-60 min, the heating is to raise the temperature to 60-80℃ and the reaction time is 1-2 h, the cooling is to cool to 20-35℃, and after adding dimethylamine, the temperature is raised again to 70-80℃ and the reaction time is 1-3 h.

6. The durable solid waste-based foamed lightweight soil according to claim 4, characterized in that, Step 2) The mass ratio of the oxidant to the reductant is 1:2-2:1, and the total mass of the oxidant and the reductant accounts for 0.01-0.3 wt% of the total mass of the unsaturated phenyl tertiary amine monomer and the alkenyl sulfonate monomer. The initiator accounts for 0.8-1.2 wt% of the total mass of the unsaturated phenyl tertiary amine monomer and the alkenyl sulfonate monomer. The mass ratio of the oil phase to the water phase is 3-4:6-7, and the total mass of the unsaturated phenyl tertiary amine monomer and the alkenyl sulfonate monomer accounts for 30-40 wt% of the water-in-oil emulsion.

7. The durable solid waste-based foamed lightweight soil according to claim 1, characterized in that, The alkyl sulfonate is selected from one or more of sodium dodecyl sulfonate, sodium hexadecyl sulfonate, and sodium petroleum sulfonate.

8. The durable solid waste-based foamed lightweight soil according to claim 1, characterized in that, The alkaline solid waste is selected from one or more combinations of red mud, steel slag, and alkali slag, and the median D50 particle size of the alkaline solid waste is 1-10 μm; the silicoaluminous solid waste is selected from one or more combinations of fly ash and blast furnace slag, and the median D50 particle size of the silicoaluminous solid waste is 1-10 μm, with a silica content of 30-55 wt% and an alumina content of 10-25 wt%; the sulfate solid waste is selected from one or more combinations of desulfurized gypsum, phosphogypsum, electrolytic manganese slag, and titanium gypsum, and the median D50 particle size of the sulfate solid waste is 1-10 μm, with an SO3 content of 35-50 wt%.

9. The method for preparing the durable solid waste-based foamed lightweight soil according to any one of claims 1-8, characterized in that, Includes the following steps: S1 mixes the composite foaming agent with water to produce foam for later use; S2 mixes alkaline solid waste, siliceous aluminum solid waste, sulfate solid waste, water-reducing agent, expanding agent, crack-resistant fiber, antifreeze agent and water evenly to make slurry for later use; S3 mixes the slurry and foam evenly, then pours and solidifies to obtain durable solid waste-based foamed lightweight soil.

10. The method for preparing durable solid waste-based foamed lightweight soil according to claim 9, characterized in that, In step S1, the mass ratio of the composite foaming agent to water is 1:50-60. The foam production involves adding the mixture of composite foaming agent and water to a foaming machine with a foaming pressure of 0.3-0.5 MPa, compressing it to produce a density of 40-60 kg / m³. 3 The foam.

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