Low-shrinkage high-strength fluidified solidified soil of solidified clay and preparation method thereof

Abstract

This invention discloses a low-shrinkage, high-strength fluidized solidified soil for solidified clay. The raw materials include: a curing agent, an activator, waste mud, pre-wetted lightweight aggregate, and water. The curing agent has a mass fraction of 5-20%, the activator has a mass fraction of 0.6%-1.8%, and the mass ratio of waste mud to pre-wetted lightweight aggregate and water is 5-7:3-5:2.5-4.5. The pre-wetted lightweight aggregate is a pre-wetted spherical porous lightweight aggregate, comprising: 10%-30% Bayer red mud, 30%-50% fly ash, 10% metakaolin, 15% quartz powder, 10% guiguang talc, and 1.5%-3% pore-forming agent. This invention utilizes the internal curing effect of the pre-wetted lightweight aggregate to solve the fluidity problem of fluidized solidified soil under low water-to-solid ratio conditions. Combined with a lower water-to-solid ratio to reduce drying shrinkage and the arching effect of the spherical lightweight aggregate to improve strength, it achieves the goal of preparing low-shrinkage, high-strength, crack-resistant fluidized solidified soil.

Description

Technical Field

[0001] This invention relates to the field of fluidized solidified soil. More specifically, this invention relates to a low-shrinkage, high-strength fluidized solidified soil of solidified clay and its preparation method. Background Technology

[0002] During the foundation construction of various building projects such as highways, airports, ports, and urban construction, billions of cubic meters of excavated slag, soil, and silt are removed annually. The vast majority of this is treated as waste soil and directly dumped and landfilled, resulting in a significant waste of land resources and potential environmental pollution during the landfill process. In recent years, the most researched approach to recycling engineering waste soil has focused on preparing fluidized solidified soil by incorporating solidifying agents and water. Before solidification, this material exists in a fluid state, requiring little or no vibration during construction. After solidification, it becomes a new type of geotechnical engineering material with certain strength, low permeability, water stability, and long-term stability.

[0003] However, in practical applications, clayey waste mud with montmorillonite as its main mineral component has high water absorption and shrinkage rates. This type of soil has a high plasticity index, easily absorbs water, and forms flocculated structures, hindering flow. Therefore, the preparation of fluidized solidified soil using clay as raw material requires a significant increase in water consumption to meet the fluidity requirements of engineering construction. However, a substantial increase in the water-to-solid ratio leads to significant drying shrinkage of the fluidized solidified soil, easily causing uneven shrinkage inside and outside the soil, resulting in numerous network cracks and severely affecting the material's molding quality. Simultaneously, because clay contains abundant organic matter, if water-reducing agents are added to control the water-to-solid ratio of the fluidized solidified soil by reducing water consumption, the adsorption of large amounts of organic matter will severely affect the water-reducing effect of the agents. Fluidized solidified soil prepared according to the set ratio (low water-to-solid ratio) will then encounter pumping difficulties.

[0004] To address the aforementioned issues, it is necessary to design a low-shrinkage, high-strength fluidized solidified soil and its preparation method, which can reduce the water-to-solid ratio while ensuring the fluidity of the fluidized solidified soil. Summary of the Invention

[0005] The purpose of this invention is to provide a low-shrinkage, high-strength fluidized solidified soil and its preparation method. By using the internal curing effect of pre-wetted lightweight aggregates, the fluidity problem of fluidized solidified soil under low water-to-solid ratio is solved, so that the prepared fluidized solidified soil has the advantages of low shrinkage, crack resistance, and high mechanical properties.

[0006] To achieve these objectives and other advantages according to the present invention, a low-shrinkage, high-strength fluidized solidified soil for solidified clay is provided, comprising: a curing agent, an activator, waste mud, pre-wetted lightweight aggregate, and water, wherein the mass fraction of the curing agent is 5-20%, the mass fraction of the activator is 0.6%-1.8%, and the mass ratio of waste mud to pre-wetted lightweight aggregate and water is 5-7:3-5:2.5-4.5; The pre-wetted lightweight aggregate is a spherical porous lightweight aggregate that has undergone pre-wetting treatment. By mass fraction, the spherical porous lightweight aggregate includes the following raw materials: 10% to 30% Bayer red mud, 30% to 50% fly ash, 10% metakaolin, 15% quartz powder, 10% guiguang talc, and 1.5% to 3% pore-forming agent.

[0007] Preferably, the low-shrinkage, high-strength fluidized solidified clay, by mass fraction, comprises the following raw materials: 15%–25% cement, 5%–15% lime, 40%–60% active mineral admixture, and 20%–30% gypsum.

[0008] Preferably, the solidified clay is a low-shrinkage, high-strength fluidized solidified soil, and the cement is one or more of silicate cement, slag silicate cement, pozzolanic silicate cement, fly ash silicate cement, and sulfoaluminate cement.

[0009] Preferably, the solidified clay is a low-shrinkage, high-strength fluid solidified soil, and the active mineral admixture includes one or more of slag, steel slag, fly ash, volcanic ash, and coal gangue.

[0010] Preferably, the solidified clay is a low-shrinkage, high-strength, fluid solidified soil, and the waste slurry is a clayey slurry with a liquid limit of 62.2% and a plastic limit of 28.7%.

[0011] Preferably, the solidified clay is a low-shrinkage, high-strength fluidized solidified soil, and the activator is one of sodium silicate, sodium carbonate, and sodium sulfate.

[0012] Preferably, the low-shrinkage, high-strength fluidized solidified soil of the solidified clay includes a method for preparing the pre-wetted lightweight aggregate comprising: S1. Weigh each raw material according to the mass ratio, mix them by dry ball milling, and then sieve to obtain mixed powder. Then add 5-9 wt% water for granulation and aging to obtain spherical particles. S2. The spherical particles are pressed into shape using a semi-dry pressing process to prepare cubic blanks and spherical blanks; S3. Place the dried cubic and spherical billets into a resistance muffle furnace and heat them to 1000-1200℃ to sinter them into spherical porous lightweight aggregates. S4. The spherical porous lightweight aggregate is dried at 105°C to constant weight and then pre-wetted to obtain pre-wetted lightweight aggregate.

[0013] Preferably, in the low-shrinkage, high-strength fluidized solidified soil of the solidified clay, in S4, the method for pre-wetting the spherical porous lightweight aggregate includes: immersing the spherical porous lightweight aggregate in deionized water until it is saturated with water, then removing it and using a wrung-out wet towel to treat the surface moisture of the material until it reaches a saturated surface-dry state, thus obtaining the pre-wetted lightweight aggregate.

[0014] Preferably, the solidified clay is a low-shrinkage, high-strength fluidized solidified soil, and the pre-wetted lightweight aggregate has a particle size of 0.15–4.75 mm.

[0015] This invention also provides a method for preparing low-shrinkage, high-strength, fluidized solidified soil, comprising: T1. Weigh the waste mud and pre-wetted lightweight aggregate according to the corresponding mass ratio; T2. After the waste mud is air-dried, it is sieved and then compounded with the pre-wetted lightweight aggregate to obtain the base soil; T3. Weigh out the curing agent, activator and water according to the mass ratio, mix the curing agent, activator and the compounded base soil evenly with a mixer, and finally add water, stir and pour into shape.

[0016] The present invention has at least the following beneficial effects: 1. The fluidized solidified soil of the present invention effectively controls drying shrinkage by reducing the water-to-solid ratio. At the same time, the use of pre-wetted lightweight aggregate can provide a certain amount of moisture in situ when the internal humidity of the fluidized solidified soil is significantly reduced, so as to promote the hydration of the surrounding cementitious materials and modify the structure and performance of the interface transition zone. This water release internal curing effect can effectively solve the fluidity problem of fluidized solidified soil under low water-to-solid ratio. Meanwhile, the spherical structure of the pre-wetted lightweight aggregate can promote the interface transition zone to have an "arch shell" structure. This arch shell interface transition zone can uniformly disperse compressive stress, improve the mechanical properties and durability of the fluidized solidified soil, so that the prepared fluidized solidified soil has the advantages of low shrinkage, crack resistance, and high strength. 2. In the preparation process of the fluidized solidified soil of the present invention, the pre-wetted lightweight aggregate is surrounded by cementitious slurry, which has a significant "ball effect". This can further improve the workability of the mixture, increase the fluidity of the fluidized solidified soil, make it easier to pump, pour and compact, and ensure the molding quality of the fluidized solidified soil. 3. The curing agent of this invention can reuse various industrial solid wastes such as flue gas desulfurization gypsum, granulated blast furnace slag powder, and circulating fluidized bed desulfurization fly ash as raw materials. It contains active CaO, SiO2, and Al2O3 components that can undergo pozzolanic reaction. When preparing fluidized solidified soil, it can give full play to the synergistic and complementary effects between various materials to meet the strength and stability requirements of fluidized solidified soil. Thus, while ensuring the reliability of fluidized solidified soil application, it greatly reduces the amount of cement used in the curing agent, which is conducive to reducing production costs and realizing the resource utilization of industrial solid waste.

[0017] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0018] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0019] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate orientations or positional relationships only for the convenience of describing this invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0020] This invention provides a low-shrinkage, high-strength fluidized solidified soil, the raw materials of which include: a curing agent, an activator, waste mud, pre-wetted lightweight aggregate, and water, wherein the mass fraction of the curing agent is 5-20%, the mass fraction of the activator is 0.6%-1.8%, and the mass ratio of waste mud to pre-wetted lightweight aggregate and water is 5-7:3-5:2.5-4.5; In the above scheme, the waste mud is a clay mud with montmorillonite as the main component, with a liquid limit of 62.2% and a plastic limit of 28.7%. The curing agent, by mass fraction, comprises the following raw materials: 15%–25% cement, 5%–15% lime, 40%–60% active mineral admixture, and 20%–30% gypsum. The cement is one or more of silicate cement, slag silicate cement, pozzolanic silicate cement, fly ash silicate cement, and sulfoaluminate cement; the mineral admixture includes one or more of slag, steel slag, fly ash, pozzolanic acid, and coal gangue. Both the lime and the gypsum can be conventional commercially available general-purpose materials. The curing agent is obtained by mixing the above raw materials in the specified mass ratio and mechanically stirring them evenly (using equipment such as a mixer). When the raw materials contain large particles (such as lumpy lime, slag, or gypsum), they need to be ground into powder before mixing with other materials. The activator is one of sodium silicate, sodium carbonate, and sodium sulfate.

[0021] The pre-wetted lightweight aggregate is a spherical porous lightweight aggregate that has undergone pre-wetting treatment, with a particle size of 0.15–4.75 mm. By mass fraction, the spherical porous lightweight aggregate comprises the following raw materials: 10%–30% Bayer red mud, 30%–50% fly ash, 10% metakaolin, 15% quartz powder, 10% guiguang talc, and 1.5%–3% pore-forming agent.

[0022] The method for preparing the pre-wetted lightweight aggregate includes: S1. Weigh each raw material according to the mass ratio (accurate to 0.01g), mix them by dry ball milling for 12 hours, and then pass them through a 200-mesh sieve to obtain mixed powder. Then add 5-9wt% water for granulation and age for 24-36 hours to obtain spherical particles (powder). S2. The spherical particles are pressed into shape using a semi-dry pressing process to prepare cubic blanks and spherical blanks. Specifically, a powder product hydraulic press is used with molds of different specifications to prepare cubic blanks with dimensions of 10mm×10mm×10mm and spherical blanks with a diameter of 10mm, and then dried at 92~102℃ for 48h. S3. Place the dried cubic and spherical blanks into a resistance muffle furnace and heat them to 1000-1200℃ to sinter them into spherical porous lightweight aggregates. Then sieve the aggregates and select spherical porous lightweight aggregates with a particle size of Φ0.15-4.75mm for later use. S4. After drying the selected spherical porous lightweight aggregates that meet the particle size requirements at 105℃ to constant weight, pre-wet them. The pre-wetting process is as follows: immerse the spherical porous lightweight aggregates in deionized water for a period of time until they are saturated with water, then remove them and use a wrung-out damp towel to remove surface moisture until they reach a saturated surface-dry state, thus obtaining pre-wetted lightweight aggregates. Specifically, after immersing the spherical porous lightweight aggregates in deionized water for the set pre-wetting time, it can be determined that they have reached a saturated state. Place the saturated spherical porous lightweight aggregates on a wrung-out damp towel, hold both ends of the towel and lift it slightly, so that the towel is concave and wraps around the material on all four sides. Alternately shake the ends of the towel up and down, allowing the lightweight aggregates to roll back and forth on the towel surface 8-10 times until there is no moisture on the material surface, thus reaching a saturated surface-dry state.

[0023] The Bayer red mud and metakaolin can both be conventional commercially available general-purpose materials; the fly ash is Class II fly ash; the quartz powder is quartz powder produced by Guangdong Yingde Quartz Sand Co., Ltd.; the Guiguang talc is Guiguang talc produced by Guilin Guiguang Talc Development Co., Ltd.; and the pore-forming agent is analytical grade CaCO3 and MgCO3 produced by Sinopharm Chemical Reagent Co., Ltd., with a purity ≥99.7%.

[0024] In the preparation of pre-wetted lightweight aggregate (spherical porous lightweight aggregate), Bayer red mud contains a relatively high amount of Fe2O3. Fe2O3 can undergo a redox reaction during high-temperature sintering to form Fe3O4, releasing O2 gas and producing a foaming effect, resulting in a lightweight aggregate with numerous micropores. Metakaolin contains a relatively high amount of SiO2 and Al2O3, which not only provides refractory components but also decomposes at high temperatures to form mullite, improving the strength of the lightweight aggregate. Guiguang talc contains a relatively high amount of SiO2 and MgO, serving as both a silicon and magnesium source, and can be used to regulate the composition of raw materials. Guangying quartz is mainly composed of SiO2; adding an appropriate amount can increase the viscosity of the liquid phase, making it difficult for expanding gases to escape. CaCO3 and MgCO3 in the pore-forming agent can provide fluxing components, optimizing the liquid phase content and viscosity. Furthermore, they can decompose at 600–800℃ to release CO2, exhibiting a good pore-forming effect. This synergistic effect with the foaming effect of Fe2O3 contributes to the formation of a high porosity and a finely interconnected pore structure in the lightweight aggregate.

[0025] During the sintering process of spherical porous lightweight aggregates in S3, a heating process occurs when the temperature inside the resistance muffle furnace is raised to 1000-1200℃. In the low-temperature section (below 712℃), CaCO3 and MgCO3 decompose upon heating, releasing CO2 and forming an initial microporous network, providing "nucleation sites" and gas channels for subsequent Fe2O3 foaming. As the temperature continues to rise, CaO and MgO produced after the decomposition of CaCO3 and MgCO3 react with SiO2 and Al2O3 in the high-temperature section to form a low-melting-point eutectic phase (such as anorthite, formed at 1034℃), reducing the viscosity of the liquid phase and making it easier for the O2 produced by Fe2O3 to expand and form pores. In the above process, without pre-forming pores with carbonates, Fe2O3 foaming alone easily forms large and isolated bubbles; while the microporous network of carbonates guides the gas to diffuse along grain boundaries and microcracks, making it easier to form a fine interconnected pore structure. This effectively optimizes the pore structure of the spherical porous lightweight aggregate, enabling it to fully absorb and store water after pre-wetting treatment, and play a role in releasing water and internal curing in the subsequent preparation of fluidized solidified soil. This successfully solves the fluidity problem of fluidized solidified soil under low water-to-solid ratio, and the prepared fluidized solidified soil has the advantages of low shrinkage, crack resistance, and high mechanical properties.

[0026] The present invention also provides a method for preparing low-shrinkage, high-strength, fluidized solidified soil of the solidified clay, comprising: T1. Weigh the waste mud and pre-wetted lightweight aggregate according to the corresponding mass ratio; T2. After the waste mud is air-dried, it is passed through a 2mm sieve. The screened waste mud is then mixed with the weighed pre-wetted lightweight aggregate to obtain the foundation soil. T3. Weigh out the curing agent, activator and water according to the mass ratio, mix the curing agent, activator and the compounded base soil evenly with a mixer, and finally add water, stir and pour into shape.

[0027] In the preparation of fluidized solidified soil, cement and lime provide an alkaline environment and early strength. Under the action of the alkaline environment and activator, the mineral admixtures undergo hydration reaction. Some hydration products fill the internal pores of soil particles, reducing porosity and density. Some hydration products gel encapsulate soil particles to form a three-dimensional network structure. Furthermore, the activator and lime work synergistically to maintain the pH value of the mixture at 10-12, which is conducive to promoting the dissociation of clay minerals and releasing SiO2 and Al2O3 to participate in the pozzolanic reaction, thereby improving the strength and stability of the solidified soil.

[0028] Example 1: A low-shrinkage, high-strength fluidized solidified clay, comprising, by mass fraction: 20% curing agent, 1% activator, 44.24% waste mud, 18.96% pre-wetted lightweight aggregate, and 15.8% water.

[0029] The curing agent, by mass fraction, is prepared by mechanically mixing the following raw materials: 15% cement, 15% lime, 50% active mineral admixture, and 20% gypsum. The cement used is silicate cement, the active mineral admixture is slag, and the remaining raw materials are all conventional commercially available general-purpose materials. The activator is sodium carbonate. The waste mud is a clayey mud with montmorillonite as its main component, with a liquid limit of 62.2% and a plastic limit of 28.7%.

[0030] The pre-wetted lightweight aggregate is prepared by the following steps: S1. Weigh out 22% Bayer red mud, 40% fly ash, 10% metakaolin, 15% quartz powder, 10% Guiguang talc, and 3% pore-forming agent by mass fraction. Mix them by dry ball milling for 12 hours and then pass them through a 200-mesh sieve to obtain mixed powder. Then add 6wt% water for granulation and age for 24 hours to obtain spherical particles (powder). S2. A semi-dry pressing process is adopted, using a powder product hydraulic press with molds of different specifications to press the spherical particles into shape. Cubic blanks with dimensions of 10mm × 10mm × 10mm and spherical blanks with a diameter of 10mm are prepared and dried at 100℃ for 48 hours. S3. Place the dried cubic and spherical blanks into a resistance muffle furnace and heat to 1200℃ to sinter and form spherical porous lightweight aggregates. Then sieve the aggregates and select spherical porous lightweight aggregates with a particle size of Φ0.15~4.75mm for later use. S4. After drying the selected spherical porous lightweight aggregate that meets the particle size requirements at 105°C to constant weight, pre-wet treatment is performed. The pre-wet treatment steps are as follows: soak the spherical porous lightweight aggregate in deionized water for 24 hours until it is saturated with water, then take it out and use a wrung-out wet towel to treat the surface moisture of the material to make it saturated and surface dry, thus obtaining the pre-wetted lightweight aggregate.

[0031] The fly ash used is Class II fly ash, the quartz powder is quartz powder produced by Guangdong Yingde Quartz Sand Co., Ltd., the Guiguang talc is Guiguang talc produced by Guilin Guiguang Talc Development Co., Ltd., the pore-forming agent is analytical grade CaCO3 and MgCO3 produced by Sinopharm Chemical Reagent Co., Ltd., with a purity ≥99.7%, and the remaining raw materials are all conventional commercially available general-purpose materials.

[0032] The low-shrinkage, high-strength, fluidized solidified clay is prepared by the following steps: T1. Weigh the waste mud and pre-wetted lightweight aggregate according to the corresponding mass ratio; T2. After the waste mud is air-dried, it is passed through a 2mm sieve. The screened waste mud is then mixed with the weighed pre-wetted lightweight aggregate to obtain the foundation soil. T3. Weigh out the curing agent, activator and water according to the mass ratio, mix the curing agent, activator and the compounded base soil evenly with a mixer, and finally add water, stir and pour into shape.

[0033] Example 2: A low-shrinkage, high-strength fluidized solidified clay, comprising, by mass fraction: 20% curing agent, 1% activator, 37.92% waste mud, 25.28% pre-wetted lightweight aggregate, and 15.8% water.

[0034] The selection and preparation methods of each raw material and the preparation method of the low-shrinkage, high-strength fluidized solidified clay are the same as in Example 1. The difference is that, by mass fraction, the curing agent used in Example 2 is prepared by mechanically stirring the following raw materials: 20% cement, 10% lime, 50% active mineral admixture, and 20% gypsum.

[0035] Example 3: A low-shrinkage, high-strength fluidized solidified clay, comprising, by mass fraction: 20% curing agent, 1% activator, 31.6% waste mud, 31.6% pre-wetted lightweight aggregate, and 15.8% water.

[0036] The selection and preparation methods of each raw material and the preparation method of the low-shrinkage, high-strength fluidized solidified clay are the same as in Example 1. The difference is that, by mass fraction, the curing agent used in Example 3 is prepared by mechanically stirring the following raw materials: 25% cement, 5% lime, 50% active mineral admixture, and 20% gypsum.

[0037] Example 4: A low-shrinkage, high-strength fluidized solidified clay, comprising, by mass fraction: 20% curing agent, 1% activator, 31.6% waste mud, 31.6% pre-wetted lightweight aggregate, and 15.8% water.

[0038] The selection and preparation methods of each raw material, as well as the preparation method of the low-shrinkage, high-strength fluidized solidified clay, are the same as in Example 1.

[0039] Comparative Example 1: A fluidized solidified soil, by mass fraction, comprises: 20% solidifying agent, 1% activator, 44.24% waste mud, 18.96% sand, and 15.8% water.

[0040] The curing agent, by mass fraction, is prepared by mechanically mixing the following raw materials: 15% cement, 15% lime, 50% active mineral admixture, and 20% gypsum. The cement used is silicate cement, and the active mineral admixture is slag. The activator is sodium carbonate. The waste slurry is a clayey slurry with montmorillonite as its main component, having a liquid limit of 62.2% and a plastic limit of 28.7%. All other raw materials are conventional, commercially available general-purpose materials.

[0041] The preparation method of the fluidized solidified soil is as follows: Weigh out the curing agent, activator, waste mud, sand and water according to the mass ratio, then mix them evenly using a mixer, and finally add water to stir and pour into shape.

[0042] Comparative Example 2: A fluidized solidified soil, by mass fraction, comprises: 20% solidifying agent, 1% activator, 37.92% waste mud, 25.28% sand, and 15.8% water.

[0043] The selection and preparation methods of each raw material and the preparation method of the fluidized solidified soil are the same as those of Comparative Example 1. The difference is that, by mass fraction, the curing agent used in Comparative Example 2 is prepared by mechanically stirring the following raw materials: 20% cement, 10% lime, 50% active mineral admixture, and 20% gypsum.

[0044] Comparative Example 3: A fluidized solidified soil, by mass fraction, comprises: 20% solidifying agent, 1% activator, 31.6% waste mud, 31.6% sand, and 15.8% water.

[0045] The selection and preparation methods of each raw material and the preparation method of the fluidized solidified soil are the same as those of Comparative Example 1. The difference is that, by mass fraction, the curing agent used in Comparative Example 3 is prepared by mechanically stirring the following raw materials: 25% cement, 5% lime, 50% active mineral admixture, and 20% gypsum.

[0046] Experimental Example: Basic Performance Testing The low-shrinkage, high-strength fluidized solidified soils prepared in Examples 1-4 and the fluidized solidified soils prepared in Comparative Examples 1-3 were sampled and tested for their basic properties, including fluidity, drying shrinkage, and compressive strength. The fluidity test was conducted according to the soft soil solidifier standard (CJ_T526-2018); the drying shrinkage test was conducted using the method in the "Standard for Basic Performance Test Methods of Building Mortar" (JGJ / T70), using a 40mm×40mm×160mm prism mold, and the length was measured and calculated using a length comparator (accuracy 0.001mm); the compressive strength test was conducted according to the geotechnical testing standard (GBT50123-2019), using a 70.7mm×70.7mm×70.7mm mold, and the 7-day and 28-day unconfined compressive strength of the fluidized solidified soil (test blocks) were tested.

[0047] The raw material formulations for each embodiment and comparative example are shown in Table 1.

[0048] Table 1 The test results of each embodiment and comparative example are shown in Table 2.

[0049] Table 2 Comparative analysis of the test results of Examples 1-Comparative Example 1, Examples 2-Comparative Example 2, and Examples 3-Comparative Example 3 shows that, under the same raw material ratio, replacing the pre-wetted lightweight aggregate in the raw materials with conventional sand (mainly sand particles, mixed with a small amount of silt or clay particles) significantly weakens the skeletal support of the material. Under the same low water-to-solid ratio conditions, the fluidity and compressive strength of the prepared fluidized solidified soil are significantly reduced, and the drying shrinkage rate is significantly increased. Therefore, the application of pre-wetted lightweight aggregate in this invention can effectively solve the fluidity problem of fluidized solidified soil under low water-to-solid ratio conditions, enabling the prepared fluidized solidified soil to simultaneously possess advantages such as low shrinkage, crack resistance, and high mechanical properties.

[0050] Comparative analysis of the test results of Examples 1, 2, 3, and 4 shows that with the increase of the pre-wetted lightweight aggregate content, its pre-wetted internal curing and skeleton functions are fully utilized, the drying shrinkage rate of the prepared fluidized solidified soil is better controlled, and the unconfined compressive strength is significantly improved. At the same time, the fluidity of the fluidized solidified soil can still be maintained at a high level (i.e., the degree of reduction is limited), so as to ensure the quality of use and molding of the fluidized solidified soil.

[0051] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A low-shrinkage, high-strength, fluidized solidified soil for solidified clay, characterized in that, The raw materials include: curing agent, activator, waste mud, pre-wetted lightweight aggregate, and water. The mass fraction of the curing agent is 5-20%, the mass fraction of the activator is 0.6%-1.8%, and the mass ratio of waste mud to pre-wetted lightweight aggregate and water is 5-7:3-5:2.5-4.

5. The pre-wetted lightweight aggregate is a spherical porous lightweight aggregate that has undergone pre-wetting treatment. By mass fraction, the spherical porous lightweight aggregate includes the following raw materials: 10% to 30% Bayer red mud, 30% to 50% fly ash, 10% metakaolin, 15% quartz powder, 10% guiguang talc, and 1.5% to 3% pore-forming agent.

2. The low-shrinkage, high-strength, fluidized solidified soil of solidified clay as described in claim 1, characterized in that, The curing agent comprises the following raw materials by mass fraction: 15%–25% cement, 5%–15% lime, 40%–60% active mineral admixture, and 20%–30% gypsum.

3. The low-shrinkage, high-strength, fluidized solidified soil of solidified clay as described in claim 2, characterized in that, The cement is one or more of the following: silicate cement, slag silicate cement, pozzolanic silicate cement, fly ash silicate cement, and sulfoaluminate cement.

4. The low-shrinkage, high-strength, fluidized solidified soil of solidified clay as described in claim 2, characterized in that, The active mineral admixture includes one or more of the following: slag, steel slag, fly ash, volcanic ash, and coal gangue.

5. The low-shrinkage, high-strength, fluidized solidified soil of solidified clay as described in claim 1, characterized in that, The waste mud is clay mud with a liquid limit of 62.2% and a plastic limit of 28.7%.

6. The low-shrinkage, high-strength, fluidized solidified soil of solidified clay as described in claim 1, characterized in that, The activator is one of sodium silicate, sodium carbonate, and sodium sulfate.

7. The low-shrinkage, high-strength, fluidized solidified soil of solidified clay as described in claim 1, characterized in that, The method for preparing the pre-wetted lightweight aggregate includes: S1. Weigh each raw material according to the mass ratio, mix them by dry ball milling, and then sieve to obtain mixed powder. Then add 5-9 wt% water for granulation and aging to obtain spherical particles. S2. The spherical particles are pressed into shape using a semi-dry pressing process to prepare cubic blanks and spherical blanks; S3. Place the dried cubic and spherical billets into a resistance muffle furnace and heat them to 1000-1200℃ to sinter them into spherical porous lightweight aggregates. S4. The spherical porous lightweight aggregate is dried at 105°C to constant weight and then pre-wetted to obtain pre-wetted lightweight aggregate.

8. The low-shrinkage, high-strength, fluidized solidified soil of solidified clay as described in claim 7, characterized in that, In S4, the method for pre-wetting the spherical porous lightweight aggregate includes: immersing the spherical porous lightweight aggregate in deionized water until it is saturated with water, then removing it and using a wrung-out wet towel to treat the surface moisture of the material until it reaches a saturated surface-dry state, thus obtaining the pre-wetted lightweight aggregate.

9. The low-shrinkage, high-strength, fluidized solidified soil of solidified clay as described in claim 7, characterized in that, The pre-wetted lightweight aggregate has a particle size of 0.15–4.75 mm.

10. The method for preparing low-shrinkage, high-strength, fluidized solidified clay according to any one of claims 1-9, characterized in that, include: T1. Weigh the waste mud and pre-wetted lightweight aggregate according to the corresponding mass ratio; T2. After the waste mud is air-dried, it is sieved and then compounded with the pre-wetted lightweight aggregate to obtain the base soil; T3. Weigh out the curing agent, activator and water according to the mass ratio, mix the curing agent, activator and the compounded base soil evenly with a mixer, and finally add water, stir and pour into shape.

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