Highway roadbed solid waste alkali slag solidified soil and construction method thereof

Abstract

The present invention discloses a kind of highway roadbed solid waste alkali residue solidified soil and its construction method, relates to road engineering technology and solid waste utilization technology field, respectively utilizes the microscopic enhancement mechanism of self-made whiskers, combines interface enhancement to form stable chemical bonds and utilizes nano-silica to meet the particle hole filling and synergistic effect, and the remaining holes after dehydration are filled with hydration products, especially silicon-containing hydrogel provides nucleation sites, accelerates product growth, nano-silica high specific surface area promotes C-S-H nucleation, and the two admixture components work together to further improve the compressive strength of solidified soil. Solve the problem that alkali residue itself has the characteristics of large water content, excessive dosage will lead to increased water content of improved soil, difficult compaction during construction, resulting in increased porosity and decreased mechanical properties.

Description

Technical Field

[0001] The present invention relates to the field of road engineering technology and solid waste utilization technology, in particular to a highway roadbed solid waste alkali residue solidified soil and a construction method thereof. Background Art

[0002] Alkali slag is a by-product of the alkali production industry, mainly consisting of white mud and salt mud. Approximately 0.3 tons of alkali slag are emitted for every ton of soda ash produced. The large amount of alkali slag discharged not only occupies land resources, but may also pollute the environment. The current comprehensive utilization rate of discharged alkali slag is low, and the treatment pressure is relatively high. Alkali slag has the characteristics of small particle size, large specific surface area, and strong adsorption capacity. It also has alkaline properties, which are conducive to stimulating the hydration activity of external curing agents such as fly ash, lime and slag. Researchers have explored the use of alkali slag-solidified soil for roadbed filling, but the alkali slag dosage is low and the comprehensive utilization efficiency is low. Alkali slag itself has the characteristic of high water content. Excessive dosage will lead to an increase in the water content of the improved soil, making it difficult to compact during construction, resulting in an increase in its porosity and a decrease in mechanical properties.

[0003] Therefore, it is of great significance to develop a method for efficiently utilizing alkali residue and all-solid waste soil solidifier to prepare highway subgrade solid waste alkali residue solidified soil and clarify its construction method. Summary of the Invention

[0004] The purpose of the present invention is to provide a highway roadbed solid waste alkali residue solidified soil and a construction method thereof, so as to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A highway roadbed solid waste alkali slag solidified soil, wherein the raw material components of the solid waste alkali slag solidified soil include, by mass, 40-55 parts of plain soil, 40-60 parts of alkali slag, 1-9 parts of a composite curing agent, and 10-20 parts of fly ash;

[0007] Furthermore, the raw material components in the composite curing agent include, by weight, 40-52 parts of slag powder, 25-30 parts of steel slag, 10-15 parts of fly ash, 10-13 parts of desulfurized gypsum, and 3-9 parts of admixtures;

[0008] Furthermore, the admixture includes modified magnesium hydroxide sulfate whiskers and nano-silicon dioxide composite particles; wherein the mass ratio of modified magnesium hydroxide sulfate whiskers to nano-silicon dioxide composite particles is 1:(1-2).

[0009] Furthermore, the preparation method of the modified magnesium hydroxide sulfate whiskers comprises the following steps:

[0010] S1: Add magnesium sulfate powder to a reaction vessel, add ammonia water, maintain the pH of the reaction system at 10.5-11.5, heat to 150-155°C for 16-18 hours, cool to room temperature, filter, wash the product with deionized water and anhydrous ethanol, and dry in vacuo at 60-65°C to obtain magnesium hydroxide sulfate whiskers;

[0011] S2: n-Butyl methacrylate and 15 wt% sodium dodecylsulfonate solution were added to a reaction vessel, stirred evenly, magnesium hydroxide sulfate whiskers were added, heated to 60-70°C for reaction for 30-35 minutes, 2 wt% maleic anhydride aqueous solution was added, heated to 85-87°C for reaction for 2-2.5 hours, washed, filtered, and dried to obtain copolymer-modified magnesium hydroxide sulfate whiskers;

[0012] S3: Add KH560 to an ethanol-water solution with a volume ratio of 9:1, adjust the pH to 4-5, stir at room temperature for 120-125 minutes, add an ethanol-water solution of the copolymer-modified magnesium hydroxide sulfate whisker, heat to 80-85°C and stir for 1.5-2 hours, filter, and vacuum dry to obtain modified magnesium hydroxide sulfate whiskers.

[0013] Furthermore, during the preparation of magnesium hydroxide sulfate whiskers, 40-45 mL of aqueous ammonia is added to every 0.01 mol of magnesium sulfate powder.

[0014] Furthermore, in the preparation process of the copolymer-modified magnesium hydroxide sulfate whiskers, the mass ratio of magnesium hydroxide sulfate whiskers: n-butyl methacrylate: maleic anhydride is 15:(20-25):(1.85-2.22).

[0015] Furthermore, during the preparation of the modified magnesium hydroxide sulfate whiskers, the amount of KH560 added was 4-5 wt % of the mass of the copolymer-modified magnesium hydroxide sulfate whiskers.

[0016] Furthermore, the method for preparing the nano-silicon dioxide composite particles comprises the following steps:

[0017] Ultrasonic dispersion of nano-silica in deionized water, addition of acrylamide and N,N'-methylenebisacrylamide crosslinker solution, stirring for 5-10 minutes, addition of initiator solution, heating to 60-65°C for reaction for 10-15 minutes, immersion of the product in deionized water for 24 hours, vacuum drying at 80-85°C for 10-12 hours, grinding, and sieving to obtain nano-silica composite particles.

[0018] Furthermore, in the preparation process of the nano-silica composite particles, the proportions of the raw material components are calculated by weight, including: 0.3-0.5 parts of nano-silica, 3-5 parts of acrylamide, and 0.6-1 parts of N,N'-methylenebisacrylamide crosslinker; in the initiator solution, the initiator is a mixture of sodium metabisulfite and sodium persulfate, and the solvent is deionized water; wherein the mass ratio of sodium metabisulfite to sodium persulfate must be 1:1, and the amount of initiator added is 1-1.2wt% of the mass of acrylamide.

[0019] A construction process for solidifying soil from solid waste alkali residue of highway subgrade comprises the following steps: surface treatment: compacting the surface of the highway subgrade;

[0020] Raw material moisture content control: the moisture content of alkali residue is controlled at 102±8%, the moisture content of raw soil is controlled at 15±2%, and the moisture content of fly ash is controlled at <8%;

[0021] Raw material loose laying and roadbed edging: Raw material loose laying: fly ash, alkali residue, composite curing agent and plain soil are loosely laid in layers on the roadbed surface in a proportioned order from bottom to top to obtain a loose layer; Roadbed edging: clay edging is performed on the roadbed to obtain edging soil;

[0022] Material mixing, layered compaction, final compaction, testing, and construction completion.

[0023] Furthermore, the thickness of the loose layer is ≤30cm, in which the fly ash loose layer has a thickness of 3±0.5cm, the alkali slag loose layer has a thickness of 15±1cm, and the plain soil loose layer has a thickness of 12±1cm; the width of the edging soil is 1.5-2cm; the raw material loose layer and roadbed edging are carried out simultaneously.

[0024] Furthermore, the preparation method of the composite curing agent includes the following steps: adding slag, steel slag, fly ash, and desulfurized gypsum into a ball mill, stirring evenly, adding admixtures, ball milling at room temperature for 15-20 minutes, and sieving to obtain the composite curing agent.

[0025] Furthermore, the physical properties of the raw soil include: natural moisture content of 21%, liquid limit of 30.5%, plastic limit of 11.84%, plasticity index of 18.66%, silt content of 69.3%, and sand content of 24.79%.

[0026] Furthermore, the chemical composition of the alkali slag includes: Ca30.3%, Na0.68%, S7.91%, Mg5.65%, Cl12.3%, Si6.95%, Al1.76%;

[0027] Furthermore, the mineral composition of the slag includes: 52.6% dihydrate gypsum, 10.4% calcium carbonate, 6.1% hemihydrate gypsum, 12.3% calcium hydroxide, 5.65% NaCl, and 6.95% SiO2;

[0028] Furthermore, the physical properties of the slag include: natural moisture content 62%, liquid limit 74.78%, plastic limit 33.71%, plasticity index 41.07%, clay content 2.97%, silt content 68.14%, and sand content 28.89%;

[0029] Furthermore, the chemical composition of the fly ash includes: CaO 3.66%, SiO 2 49.74%, Al 2 O 3 35.18%, MgO 0.37%, TiO 2 2.25%, SO 3 1.24%, Fe 2 O 3 5.40%, and K 2 O 1.37%.

[0030] Furthermore, the nano-silicon dioxide has a particle size of 60-70 nm.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention modifies the whiskers through in-situ polymerization of n-butyl acrylate and maleic anhydride, enhancing their dispersion and compatibility during mixing. The surface is then modified with a silane coupling agent, leveraging the whiskers' inherent microscopic reinforcement mechanism and interfacial reinforcement to form stable chemical bonds (such as hydrogen bonds and Si-O-Si bonds), significantly improving the compressive strength of the solidified soil. Simultaneously, the silane coupling agent-modified whiskers enhance the dispersion of the nano-CO2 composite. The hydrogel properties of the nano-CO2 composite slowly release water after absorbing water, promoting subsequent hydration and increasing the degree of hydration. Through pore-filling and synergistic effects, the pores remaining after dehydration are filled with hydration products (CH4 and CSH). The silicon-containing hydrogel, in particular, provides nucleation sites, accelerating product growth, while the high specific surface area of ​​the nano-silica promotes CSH nucleation. The two admixture components work together to further enhance the compressive strength of the solidified soil. DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0034] In the following examples, the preparation method of modified magnesium hydroxide sulfate whiskers comprises the following steps:

[0035] S1: Add 0.01 mol of magnesium sulfate powder to a reaction vessel, add 40 mL of ammonia water, maintain the pH of the reaction system at 11, heat to 150°C for 16 hours, cool to room temperature, filter, wash the product with deionized water and anhydrous ethanol, and dry in vacuo at 60°C to obtain magnesium hydroxide sulfate whiskers;

[0036] S2: 20 g of n-butyl methacrylate and 15 wt% sodium dodecylsulfonate solution were added to a reaction vessel and stirred evenly. 15 g of magnesium hydroxide sulfate whiskers were added and heated to 60° C. for 30 min. A maleic anhydride aqueous solution containing 1.85 g of maleic anhydride was added and heated to 85° C. for 2 h. The mixture was washed, filtered, and dried to obtain copolymer-modified magnesium hydroxide sulfate whiskers.

[0037] S3: Add 4 wt% KH560 to an ethanol-water solution with a volume ratio of 9:1, adjust the pH to 4, stir at room temperature for 120 min, add an ethanol-water solution of copolymer-modified magnesium hydroxide sulfate whiskers, heat to 80°C and stir for 1.5 h, filter, and vacuum dry to obtain modified magnesium hydroxide sulfate whiskers.

[0038] The preparation method of nano-silicon dioxide composite particles comprises the following steps:

[0039] 0.3 parts of nano-silica were ultrasonically dispersed in deionized water, 3 parts of acrylamide and an N,N'-methylenebisacrylamide crosslinker solution containing 0.6 parts of N,N'-methylenebisacrylamide crosslinker were added, and the mixture was stirred for 5 minutes. An initiator solution containing 1 wt% of an initiator was added, and the mixture was heated to 60°C for 10 minutes. The product was immersed in deionized water for 24 hours, vacuum-dried at 80°C for 10 hours, ground, and sieved to obtain nano-silica composite particles.

[0040] Example 1: A construction process for solidifying soil from solid waste alkali residue of a highway subgrade, comprising the following steps: surface treatment: compacting the surface of the highway subgrade;

[0041] Raw material moisture content control: the moisture content of alkali residue is controlled at 102%, the moisture content of raw soil is controlled at 15%, and the moisture content of fly ash is controlled at 6%;

[0042] Loose laying of raw materials and roadbed edging: Loose laying of raw materials: 10 parts of fly ash, 40 parts of alkali residue, 6 parts of composite curing agent, and 40 parts of plain soil are loosely laid on the roadbed surface in layers from bottom to top to obtain a loose layer; Roadbed edging: The roadbed is edged with clay to obtain edge soil;

[0043] Material mixing: A five-furrow plow and road mixer were used for mixing, with the five-furrow plow turning the material three times and the road mixer turning the material once. The moisture content was controlled at 22% during the mixing process, and there was no interlayer ash band after mixing. The mixing width was 30cm for each layer.

[0044] Layered rolling: First, use a heavy-duty roller to perform static rolling once, then a heavy-duty vibratory roller to perform strong vibration rolling once and weak vibration rolling once. Roll from the edge of the roadbed toward the inside, with each wheel rolling. The overlapping width of the wheel tracks should be no less than 1 / 3 of the width of a single wheel. One pass is considered one pass if the wheel tracks on one side completely cover the entire working surface.

[0045] Final compaction: Use a heavy roller to perform final compaction once, with the wheel track overlap width not less than 1 / 3 of the single wheel width;

[0046] Testing: Conduct compaction testing;

[0047] Complete construction.

[0048] The preparation method of the composite curing agent comprises the following steps: adding 52 parts of slag, 25 parts of steel slag, 10 parts of fly ash, and 13 parts of desulfurized gypsum into a ball mill, stirring evenly, adding 3 parts of an admixture, ball milling at room temperature for 15 minutes, and sieving to obtain the composite curing agent;

[0049] The admixture consists of modified magnesium hydroxide sulfate whiskers and nano silicon dioxide composite particles in a mass ratio of 1:1.

[0050] Example 2: A construction process for solidifying soil from solid waste alkali residue of highway subgrade, comprising the following steps: A method for preparing nano-silicon dioxide composite particles, comprising the following steps:

[0051] 0.5 parts of nano-silica were ultrasonically dispersed in deionized water, 5 parts of acrylamide and an N,N'-methylenebisacrylamide crosslinker solution containing 1 part of N,N'-methylenebisacrylamide crosslinker were added, and the mixture was stirred for 5 minutes. An initiator solution containing 1 wt% of an initiator was added, and the mixture was heated to 60°C for 10 minutes. The product was immersed in deionized water for 24 hours, vacuum-dried at 80°C for 10 hours, ground, and sieved to obtain nano-silica composite particles.

[0052] Surface treatment: compact the surface of the highway subgrade;

[0053] Raw material moisture content control: the moisture content of alkali residue is controlled at 102%, the moisture content of raw soil is controlled at 15%, and the moisture content of fly ash is controlled at 6%;

[0054] Loose laying of raw materials and roadbed edging: Loose laying of raw materials: 10 parts of fly ash, 40 parts of alkali residue, 6 parts of composite curing agent, and 40 parts of plain soil are loosely laid on the roadbed surface in layers from bottom to top to obtain a loose layer; Roadbed edging: The roadbed is edged with clay to obtain edge soil;

[0055] Material mixing: A five-furrow plow and road mixer were used for mixing, with the five-furrow plow turning the material three times and the road mixer turning the material once. The moisture content was controlled at 22% during the mixing process, and there was no interlayer ash band after mixing. The mixing width was 30cm for each layer.

[0056] Layered rolling: First, use a heavy-duty roller to perform static rolling once, then a heavy-duty vibratory roller to perform strong vibration rolling once and weak vibration rolling once. Roll from the edge of the roadbed toward the inside, with each wheel rolling. The overlapping width of the wheel tracks should be no less than 1 / 3 of the width of a single wheel. One pass is considered one pass if the wheel tracks on one side completely cover the entire working surface.

[0057] Final compaction: Use a heavy roller to perform final compaction once, with the wheel track overlap width not less than 1 / 3 of the single wheel width;

[0058] Testing: Conduct compaction testing;

[0059] Complete construction.

[0060] The remaining steps are the same as those in Example 1.

[0061] Example 3: A construction process for solidifying soil from solid waste alkali residue of highway subgrade, comprising the following steps: the admixture is composed of modified magnesium hydroxide sulfate whiskers and nano-silicon dioxide composite particles in a mass ratio of 1:1.5;

[0062] Surface treatment: compact the surface of the highway subgrade;

[0063] Raw material moisture content control: the moisture content of alkali residue is controlled at 102%, the moisture content of raw soil is controlled at 15%, and the moisture content of fly ash is controlled at 6%;

[0064] Loose laying of raw materials and roadbed edging: Loose laying of raw materials: 10 parts of fly ash, 40 parts of alkali residue, 6 parts of composite curing agent, and 40 parts of plain soil are loosely laid on the roadbed surface in layers from bottom to top to obtain a loose layer; Roadbed edging: The roadbed is edged with clay to obtain edge soil;

[0065] Material mixing: A five-furrow plow and road mixer were used for mixing, with the five-furrow plow turning the material three times and the road mixer turning the material once. The moisture content was controlled at 22% during the mixing process, and there was no interlayer ash band after mixing. The mixing width was 30cm for each layer.

[0066] Layered rolling: First, use a heavy-duty roller to perform static rolling once, then a heavy-duty vibratory roller to perform strong vibration rolling once and weak vibration rolling once. Roll from the edge of the roadbed toward the inside, with each wheel rolling. The overlapping width of the wheel tracks should be no less than 1 / 3 of the width of a single wheel. One pass is considered one pass if the wheel tracks on one side completely cover the entire working surface.

[0067] Final compaction: Use a heavy roller to perform final compaction once, with the wheel track overlap width not less than 1 / 3 of the single wheel width;

[0068] Testing: Conduct compaction testing;

[0069] Complete construction.

[0070] The remaining steps are the same as those in Example 2.

[0071] Example 4: A construction process for solidifying soil from solid waste alkali residue of highway subgrade, comprising the following steps: the admixture is composed of modified magnesium hydroxide sulfate whiskers and nano-silicon dioxide composite particles in a mass ratio of 1:2;

[0072] Surface treatment: compact the surface of the highway subgrade;

[0073] Raw material moisture content control: the moisture content of alkali residue is controlled at 102%, the moisture content of raw soil is controlled at 15%, and the moisture content of fly ash is controlled at 6%;

[0074] Loose laying of raw materials and roadbed edging: Loose laying of raw materials: 10 parts of fly ash, 40 parts of alkali residue, 6 parts of composite curing agent, and 40 parts of plain soil are loosely laid on the roadbed surface in layers from bottom to top to obtain a loose layer; Roadbed edging: The roadbed is edged with clay to obtain edge soil;

[0075] Material mixing: A five-furrow plow and road mixer were used for mixing, with the five-furrow plow turning the material three times and the road mixer turning the material once. The moisture content was controlled at 22% during the mixing process, and there was no interlayer ash band after mixing. The mixing width was 30cm for each layer.

[0076] Layered rolling: First, use a heavy-duty roller to perform static rolling once, then a heavy-duty vibratory roller to perform strong vibration rolling once and weak vibration rolling once. Roll from the edge of the roadbed toward the inside, with each wheel rolling. The overlapping width of the wheel tracks should be no less than 1 / 3 of the width of a single wheel. One pass is considered one pass if the wheel tracks on one side completely cover the entire working surface.

[0077] Final compaction: Use a heavy roller to perform final compaction once, with the wheel track overlap width not less than 1 / 3 of the single wheel width;

[0078] Testing: Conduct compaction testing;

[0079] Complete construction.

[0080] The remaining steps are the same as those in Example 2.

[0081] Example 5: A construction process for solidifying soil from solid waste alkali slag of a highway subgrade, comprising the following steps: A method for preparing the composite curing agent comprises the following steps: adding 52 parts of slag, 25 parts of steel slag, 10 parts of fly ash, and 13 parts of desulfurized gypsum into a ball mill, stirring evenly, adding 9 parts of an admixture, ball-milling at room temperature for 15 minutes, and sieving to obtain the composite curing agent;

[0082] Surface treatment: compact the surface of the highway subgrade;

[0083] Raw material moisture content control: the moisture content of alkali residue is controlled at 102%, the moisture content of raw soil is controlled at 15%, and the moisture content of fly ash is controlled at 6%;

[0084] Loose laying of raw materials and roadbed edging: Loose laying of raw materials: 10 parts of fly ash, 40 parts of alkali residue, 6 parts of composite curing agent, and 40 parts of plain soil are loosely laid on the roadbed surface in layers from bottom to top to obtain a loose layer; Roadbed edging: The roadbed is edged with clay to obtain edge soil;

[0085] Material mixing: A five-furrow plow and road mixer were used for mixing, with the five-furrow plow turning the material three times and the road mixer turning the material once. The moisture content was controlled at 22% during the mixing process, and there was no interlayer ash band after mixing. The mixing width was 30cm for each layer.

[0086] Layered rolling: First, use a heavy-duty roller to perform static rolling once, then a heavy-duty vibratory roller to perform strong vibration rolling once and weak vibration rolling once. Roll from the edge of the roadbed toward the inside, with each wheel rolling. The overlapping width of the wheel tracks should be no less than 1 / 3 of the width of a single wheel. One pass is considered one pass if the wheel tracks on one side completely cover the entire working surface.

[0087] Final compaction: Use a heavy roller to perform final compaction once, with the wheel track overlap width not less than 1 / 3 of the single wheel width;

[0088] Testing: Conduct compaction testing;

[0089] Complete construction.

[0090] The remaining steps are the same as those in Example 4.

[0091] Comparative Example 1: A construction process for solidifying soil from solid waste alkali residue of highway subgrade, comprising the following steps: A method for preparing nano-silicon dioxide composite particles, comprising the following steps:

[0092] 0.03 parts of nano-silica were ultrasonically dispersed in deionized water, 3 parts of acrylamide and an N,N'-methylenebisacrylamide crosslinker solution containing 0.6 parts of N,N'-methylenebisacrylamide crosslinker were added, and the mixture was stirred for 5 minutes. An initiator solution containing 1 wt% of an initiator was added, and the mixture was heated to 60°C for 10 minutes. The product was immersed in deionized water for 24 hours, vacuum-dried at 80°C for 10 hours, ground, and sieved to obtain nano-silica composite particles.

[0093] The remaining steps are the same as those in Example 1.

[0094] Comparative Example 2: A construction process for solidifying soil from solid waste alkali residue of highway subgrade, comprising the following steps: A method for preparing nano-silicon dioxide composite particles, comprising the following steps:

[0095] 0.3 parts of nano-silica were ultrasonically dispersed in deionized water, 3 parts of acrylamide and an N,N'-methylenebisacrylamide crosslinker solution containing 0.15 parts of N,N'-methylenebisacrylamide crosslinker were added, and the mixture was stirred for 5 minutes. An initiator solution containing 1 wt% of an initiator was added, and the mixture was heated to 60°C for 10 minutes. The product was immersed in deionized water for 24 hours, vacuum-dried at 80°C for 10 hours, ground, and sieved to obtain nano-silica composite particles.

[0096] The remaining steps are the same as those in Example 1.

[0097] Comparative Example 3: A construction process for solidifying soil from solid waste alkali residue of highway subgrade, comprising the following steps: the admixture is modified magnesium hydroxide sulfate whisker in a mass ratio of ;

[0098] The remaining steps are the same as those in Example 1.

[0099] Comparative Example 4: A construction process for solidifying soil from solid waste alkali residue of highway subgrade, comprising the following steps: the admixture is nano-silicon dioxide composite particles in a mass ratio of ;

[0100] The remaining steps are the same as those in Example 1.

[0101] Comparative Example 5: A construction process for solidifying soil from solid waste alkali residue of highway subgrade, comprising the following steps: The preparation method of the composite curing agent, comprising the following steps:

[0102] S1: 1 g of nano-silica was added to 40 mL of a mixture of anhydrous ethanol and water in a volume ratio of 9:1, and ultrasonically dispersed. KH560 solution was added and heated to 60°C for 12 h to obtain a KH560-grafted nano-silica particle dispersion.

[0103] S2: Immerse magnesium hydroxide sulfate whiskers in a dispersion of KH560 grafted nano-silica particles, heat to 60°C for reaction for 12 hours, wash the product with deionized water and anhydrous ethanol, and vacuum dry at 70°C to obtain a composite curing agent.

[0104] The remaining steps are the same as those in Example 1.

[0105] Experiment: Compressive strength test: The solid waste alkali slag solidified soil prepared in the above examples and comparative examples was used to make three 100mm×100mm×100mm solid waste alkali slag solidified soil specimens, which were cured to the specified age and tested for compressive strength, and the average value was taken.

[0106] The experimental data are shown in Table 1 below.

[0107] Table 1 Compressive strength test data of solid waste alkali residue solidified soil

[0108] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Compressive strength 28d / MPa 5.42 5.77 6.22 6.72 7.56 4.62 4.56 3.66 3.92 5.30

[0109] Conclusion: The solid waste alkali residue solidified soil prepared by the present invention has excellent compressive strength.

[0110] In Comparative Example 1, only 0.03 parts of nano-silica were added, resulting in the adsorption of water molecules and the nucleation of hydration products, reduced pore filling capacity, and insufficient hydration. In Comparative Example 2, only 0.15 parts of N,N'-methylenebisacrylamide crosslinker were added, resulting in a low crosslinking density structure, which led to an increase in the size of the pores formed and a decrease in the compressive strength.

[0111] Comparative Examples 3 and 4 respectively used modified magnesium hydroxide sulfate whiskers and nano-silicon dioxide composite particles as admixtures. A single curing agent had no synergistic effect, and the dispersion performance was reduced, resulting in a decrease in compressive strength.

[0112] In Comparative Example 5, nano-silicon dioxide is directly attached to the surface of the whiskers. Its dispersion effect as an additive is lower than that of the embodiment, resulting in a decrease in compressive strength.

[0113] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A highway subgrade solid waste alkali residue solidified soil, characterized by: The raw material components of the solid waste alkali slag solidified soil include, by weight, 40-55 parts of plain soil, 40-60 parts of alkali slag, 1-9 parts of composite curing agent and 10-20 parts of fly ash; The raw material components of the composite curing agent include, by weight, 40-52 parts of slag powder, 25-30 parts of steel slag, 10-15 parts of fly ash, 10-13 parts of desulfurized gypsum, and 3-9 parts of admixtures; The admixture includes modified magnesium hydroxide sulfate whiskers and nano-silicon dioxide composite particles; wherein the mass ratio of modified magnesium hydroxide sulfate whiskers to nano-silicon dioxide composite particles is 1:(1-2); The preparation method of the modified magnesium hydroxide sulfate whisker comprises the following steps: S1: Add magnesium sulfate powder to a reaction vessel, add ammonia water, maintain the pH of the reaction system at 10.5-11.5, heat to 150-155°C for 16-18 hours, cool to room temperature, filter, wash the product with deionized water and anhydrous ethanol, and dry in vacuo at 60-65°C to obtain magnesium hydroxide sulfate whiskers; S2: n-Butyl methacrylate and 15 wt% sodium dodecylsulfonate solution were added to a reaction vessel, stirred evenly, magnesium hydroxide sulfate whiskers were added, heated to 60-70°C for reaction for 30-35 minutes, 2 wt% maleic anhydride aqueous solution was added, heated to 85-87°C for reaction for 2-2.5 hours, washed, filtered, and dried to obtain copolymer-modified magnesium hydroxide sulfate whiskers; S3: Add KH560 to an ethanol-water solution at a volume ratio of 9:1, adjust the pH to 4-5, stir at room temperature for 120-125 minutes, add an ethanol-water solution of the copolymer-modified magnesium hydroxide sulfate whiskers, heat to 80-85°C, stir and react for 1.5-2 hours, filter, and vacuum dry to obtain modified magnesium hydroxide sulfate whiskers; The method for preparing the nano-silicon dioxide composite particles comprises the following steps: Ultrasonic dispersion of nano-silica in deionized water, addition of acrylamide and N,N'-methylenebisacrylamide crosslinker solution, stirring for 5-10 minutes, addition of initiator solution, heating to 60-65°C for reaction for 10-15 minutes, immersion of the product in deionized water for 24 hours, vacuum drying at 80-85°C for 10-12 hours, grinding, and sieving to obtain nano-silica composite particles.

2. The highway subgrade solid waste alkali residue solidified soil according to claim 1, characterized in that: During the preparation of magnesium hydroxide sulfate whiskers, 40-45 mL of ammonia water was added to every 0.01 mol of magnesium sulfate powder.

3. The highway subgrade solid waste alkali residue solidified soil according to claim 1, characterized in that: In the preparation process of the copolymer-modified magnesium hydroxide sulfate whisker, the mass ratio of magnesium hydroxide sulfate whisker: n-butyl methacrylate: maleic anhydride is 15:(20-25):(1.85-2.22).

4. The highway subgrade solid waste alkali residue solidified soil according to claim 1, characterized in that: During the preparation of the modified magnesium hydroxide sulfate whiskers, the amount of KH560 added was 4-5 wt% of the mass of the copolymer-modified magnesium hydroxide sulfate whiskers.

5. The highway subgrade solid waste alkali residue solidified soil according to claim 1, characterized in that: During the preparation of nano-silica composite particles, the proportions of the raw material components, calculated by mass, include: 0.3-0.5 parts of nano-silica, 3-5 parts of acrylamide, and 0.6-1 parts of N,N'-methylenebisacrylamide crosslinker; in the initiator solution, the initiator is a mixture of sodium metabisulfite and sodium persulfate, and the solvent is deionized water; wherein the mass ratio of sodium metabisulfite to sodium persulfate is 1:1, and the amount of initiator added is 1-1.2wt% of the mass of acrylamide.

6. A construction process for solidifying soil using solid waste alkali residue from highway subgrade according to any one of claims 1 to 5, characterized in that: The method includes the following steps: surface treatment: compacting the surface of the highway subgrade; Raw material moisture content control: the moisture content of alkali residue is controlled at 102±8%, the moisture content of raw soil is controlled at 15±2%, and the moisture content of fly ash is controlled at <8%; Raw material loose laying and roadbed edging: Raw material loose laying: fly ash, alkali residue, composite curing agent and plain soil are loosely laid in layers on the roadbed surface in a proportioned order from bottom to top to obtain a loose layer; Roadbed edging: clay edging is performed on the roadbed to obtain edging soil; Material mixing, layered compaction, final compaction, testing, and construction completion.

7. The construction process for solidifying soil from solid waste alkali residue of highway subgrade according to claim 6, characterized in that: The thickness of the loose layer is ≤30cm, in which the fly ash loose layer has a thickness of 3±0.5cm, the alkali slag loose layer has a thickness of 15±1cm, and the plain soil loose layer has a thickness of 12±1cm; the width of the edging soil is 1.5-2cm; the raw material loose layer and roadbed edging are carried out simultaneously.

8. The highway subgrade solid waste alkali residue solidified soil according to claim 1, characterized in that: The preparation method of the composite curing agent comprises the following steps: adding slag, steel slag, fly ash and desulfurized gypsum into a ball mill, stirring evenly, adding an admixture, ball milling at room temperature for 15-20 minutes, and sieving to obtain the composite curing agent.