High-fluidity under-sea non-dispersible high-performance solidified sludge soil and preparation method thereof

Abstract

The invention discloses high-fluidity under-sea non-dispersible high-performance solidified sludge soil and a preparation method thereof, and belongs to the technical field of ocean engineering seabed leveling, repairing and scour prevention. Setting of a curing agent, a coupling agent and a flocculating agent is determined according to different mineral compositions of the sludge. The chitosan quaternary ammonium salt can be used after being prepared into a solution by adding deionized water, and in order to ensure that the chitosan quaternary ammonium salt is fully dissolved, when the chitosan quaternary ammonium salt solution is prepared, the ratio of the chitosan quaternary ammonium salt to the deionized water is not greater than 1: 3. According to the solidified sludge soil and the preparation method thereof, the underwater non-dispersing performance of the solidified sludge soil in a marine environment is remarkably improved by setting the curing agent, the coupling agent and the flocculating agent according to mineral components of the sludge soil on an engineering site, and meanwhile, the flowing performance of the solidified sludge soil is reserved to meet construction requirements. Various mechanical properties of the solidified silt soil are effectively improved, and the solidified silt soil has good compression resistance and bonding performance and has guiding significance in the technical field of ocean engineering seabed leveling, repairing and scouring resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of seabed leveling, repair and anti-erosion in ocean engineering, and particularly relates to a highly fluid underwater non-dispersive high-performance solidified silt soil and a preparation method thereof. Background Art

[0002] A large amount of silt generated in China's ocean engineering construction has become an urgent problem to be solved. These silts not only have low structural strength, but also have a high degree of spatio-temporal variability in material properties and are enriched with various heavy metals, posing challenges to the environment and resource utilization. The traditional treatment method is to discard the silt in land or offshore areas that will not be developed in the short term after approval by the competent department. This approach not only wastes land resources, but may also induce geological environmental disasters and generate huge transportation costs. Therefore, it is particularly important to realize the near-source and on-site resource utilization of silt.

[0003] Currently, an important way of silt resource utilization is to solidify it based on cement-based materials. By controlling the ratio of cement content to initial water content (i.e., the glue ratio), the mechanical properties of the solidified silt soil are expected to be regulated. However, if the solidified silt soil is applied to the technical fields of seabed leveling, repair and anti-erosion, its fluidity and underwater non-dispersive performance also need to be considered. Existing research rarely involves this field, and a few related studies lack universality. The main reason is that the high variability of silt properties leads to significant fluctuations in the performance of solidified silt soil. Marine engineering silt is mainly composed of clay minerals (such as kaolinite, montmorillonite, illite, etc.), associated minerals (such as quartz, mica, feldspar, etc.), and a small amount of carbonate, trace amounts of sulfate, phosphate and organic matter. Its basic physical and chemical properties are mainly determined by clay minerals. Therefore, based on the qualitative and quantitative characterization results of clay minerals in silt, the preparation ratio of the solidified silt soil is determined in the present invention to mitigate the negative impact brought by the high variability of silt properties. In addition, most of the flocculants of existing underwater non-dispersive materials are water-soluble synthetic organic polymers, such as polyacrylamide, which may cause pollution to the marine environment. The present invention uses a biopolymer flocculant solution - chitosan quaternary ammonium salt solution as the flocculant to achieve significant ecological benefits.

[0004] In summary, starting from the actual engineering requirements, there is an urgent need to invent a highly fluid, underwater non-dispersive, high-performance solidified silt soil and a preparation method thereof based on the physical and chemical properties of silt, so as to realize the near-source and on-site resource utilization of marine engineering silt, reduce environmental pollution and improve economic benefits at the same time. Summary of the Invention

[0005] Aiming at the problems in the related technologies, the present invention provides a highly fluid underwater non-dispersive high-performance solidified silt soil and a preparation method thereof to overcome the above-mentioned technical problems existing in the existing related technologies.

[0006] The present invention adopts the following technical solutions: a high-fluidity underwater non-dispersible high-performance solidified silt soil, comprising the following components: silt, cement, fly ash, acrylate emulsion, silica fume, chitosan quaternary ammonium salt, and powdered water reducer; Among them, the physical and chemical properties of the silt are determined by one or two of T-O type clay minerals or T-O-T type clay minerals; based on the physical and chemical properties of the silt, the parts ratio between the cement and the silica fume, and the parts ratio between the cement and the fly ash are determined.

[0007] In a further embodiment, when the physical and chemical properties of the silt are determined by T-O type clay minerals, the parts ratio of the cement to the silica fume is 1:(0.4 - 0.6); The parts ratio of the cement to the fly ash is 1:(0.01 - 0.2).

[0008] In a further embodiment, when the physical and chemical properties of the silt are determined by T-O-T type clay minerals, the parts ratio of the cement to the silica fume is 1:(0.01 - 0.2); The parts ratio of the cement to the fly ash is 1:(0.4 - 0.5).

[0009] In a further embodiment, when the physical and chemical properties of the silt are jointly determined by T-O type clay minerals and T-O-T type clay minerals, the parts ratio of the cement to the silica fume is 1:(0.2 - 0.4); The parts ratio of the cement to the fly ash is 1:(0.2 - 0.4).

[0010] In a further embodiment, it comprises the following components according to the parts ratio: 250 - 500 parts of silt, 100 - 200 parts of cement, 1 - 50 parts of fly ash, 30 - 100 parts of acrylate emulsion, 1 - 60 parts of silica fume, 1 - 2 parts of chitosan quaternary ammonium salt, and 1 - 2 parts of powdered water reducer.

[0011] A preparation method for preparing the high-fluidity underwater non-dispersible high-performance solidified silt soil as described above, comprising the following steps: Step 1: Determine the physical and chemical properties of the silt; Step 2: Add deionized water to the chitosan quaternary ammonium salt to obtain a chitosan quaternary ammonium salt solution; Step 3: Determine the parts ratio among the silt, cement, silica fume, and fly ash according to the physical and chemical properties in Step 1, weigh and mix and stir until uniform to obtain dry materials; Step 4: Mix and stir the dry materials obtained in Step 3 with the acrylate emulsion, and slowly add the powdered water reducer and the chitosan quaternary ammonium salt solution, and stir evenly until the cement has no agglomeration and meets the expected fluidity.

[0012] In a further embodiment, the physical and chemical properties in Step 1 are determined by one or both of T-O type clay minerals or T-O-T type clay minerals; The following method is used for characterization and determination: 29 One of Si-nuclear magnetic resonance, X-ray total spectrum fitting or thermogravimetric analysis.

[0013] In a further embodiment, the preparation process of the chitosan quaternary ammonium salt solution in Step 2 includes: Weigh chitosan quaternary ammonium salt with a substitution degree greater than 90% and a molecular weight higher than 4.8×10 4 and add it to the reaction kettle, and add deionized water; the mass ratio of the chitosan quaternary ammonium salt to the deionized water is less than 1:3; Stir at a speed of 120-180 revolutions per minute at 75-90 °C until completely dissolved.

[0014] In a further embodiment, the solid content of the acrylate emulsion is 30-50%.

[0015] In a further embodiment, the stirring duration in Step 4 is 20-30 minutes.

[0016] The beneficial technical effects of the present invention: For the solidified silt and its preparation method, based on the qualitative and quantitative characterization results of clay minerals in the silt, the preparation ratio of the solidified silt is determined, avoiding the problem of significant fluctuations in the performance of the solidified silt caused by the high variability of the silt properties, and realizing the near-site and in-situ resource utilization of the silt. At the same time, for the solidified silt and its preparation method, through the setting of the curing agent, coupling agent, and flocculant, the underwater non-dispersible performance of the solidified silt in the marine environment is significantly improved, while retaining the fluidity of the solidified silt to meet the construction requirements. In addition, the mechanical properties of the solidified silt are effectively improved, with good compressive and bonding properties, which has guiding significance in the fields of seabed leveling, repair and anti-scour technology in marine engineering.

[0017] The curing agent (cement, fly ash) and the flocculant (silica fume, chitosan quaternary ammonium salt) form a ternary synergistic network through the coupling agent (acrylate emulsion). The Ca generated by the hydration of cement 2+It combines with the hydroxyl groups on the surface of silica powder through ionic bonds to form an initial C-S-H gel skeleton; the carboxyl groups in the acrylate emulsion form covalent bonds with the Si-O groups on the surface of C-S-H through esterification reactions, enhancing the toughness of the skeleton; the Al2O3 on the surface of fly ash dissociates into Al-O groups in an alkaline environment and combines with the quaternary ammonium cations of chitosan quaternary ammonium salt through electrostatic interactions. At the same time, the spherical particles of fly ash are embedded in the topological network formed by chitosan long chains, enhancing the underwater anti-dispersion property; the powdered water reducer (polycarboxylate type) disperses cement particles through steric hindrance effects, while the acrylate emulsion reduces the friction coefficient between flocs through the "ball bearing effect", and the two cooperate to regulate fluidity.

[0018] The quaternary ammonium groups of chitosan quaternary ammonium salt neutralize the negative charges on the surface of clay minerals to form a dense adsorption layer; at the same time, the reactive SiO2 of silica powder forms Si-O-C bonds with the hydroxyl groups of chitosan through dehydration condensation, strengthening the interfacial chelation effect under dynamic pH regulation; silica powder and fly ash, through the complementarity of reaction activity and particle size grading, respectively dominate the formation of early strength and the filling of later pores, forming a dense structure with "nano-micron" nesting. Acrylate and water reducer then construct a hydrogen bond stress transfer chain under the adsorption competition mechanism to achieve the dynamic balance of rheological properties. Each component forms an inseparable synergistic system through chemical bond interaction, microstructure interpenetration and macroscopic property coupling, fundamentally overcoming the performance limitations of single-functional materials. Brief Description of the Drawings

[0019] Figure 1 are the crystal structures and scanning electron microscope images of natural kaolinite and montmorillonite.

[0020] Figure 2 is the quantitative analysis diagram of the mineral composition of the silt raw material by the XRD-Rietveld method in Example 2.

[0021] Figure 3 is the test effect diagram of the non-dispersibility in Example 2.

[0022] Figure 4 is the quantitative analysis diagram of the mineral composition of the silt raw material by the XRD-Rietveld method in Example 3.

[0023] Figure 5 is the test effect diagram of the non-dispersibility in Example 3.

[0024] Figure 6 is the quantitative analysis diagram of the mineral composition of the silt raw material by the XRD-Rietveld method in Example 4.

[0025] Figure 7 is the test effect diagram of the non-dispersibility in Example 4. Detailed Description of the Embodiments

[0026] To further illustrate each embodiment, the present invention provides accompanying drawings, which are a part of the disclosure of the present invention. These drawings mainly serve to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention.

[0027] Example 1 This embodiment provides a highly fluid underwater non-dispersible high-performance solidified silt soil, which includes the following components: silt, cement, fly ash, acrylate emulsion, silica fume, chitosan quaternary ammonium salt, and powdered water reducer.

[0028] Specifically, the cement and fly ash used in this embodiment are used as solidifying agents. The cement is P·O42.5 ordinary Portland cement, and the fly ash is Class I fly ash. The cement can significantly enhance the mechanical properties of the solidified silt soil. The silicate gel generated by the fly ash can fill the cracks and pores in the matrix. In addition, the fly ash can also improve the thixotropy and fluidity of the fresh paste, optimize the construction performance, and ensure the development of the later strength of the solidified silt soil.

[0029] Furthermore, silica fume and chitosan quaternary ammonium salt are used as flocculants. Silica fume has high reactivity and specific surface area. Its high reactivity enables it to generate C-S-H gel with gelling properties, and its high specific surface area enables it to more effectively adsorb surrounding ions and molecules, form flocs, and thus improve the strength and stability of the solidified silt soil in water. Due to its long-chain structure and tendency to become a positively charged electrolyte, chitosan quaternary ammonium salt plays multiple roles such as electro-neutralization, bridging, and chelation on the negatively charged colloid system existing in the solidified silt system, enhancing the non-dispersibility of the solidified silt soil in water.

[0030] Correspondingly, the powdered water reducer can effectively improve the fluidity of the cement mortar, greatly improve the construction performance of the modified cement mortar, and have excellent underwater construction performance and working performance.

[0031] The coupling agent is an acrylate emulsion with a solid content of 45%. The acrylate emulsion can form a continuous film between the particle agglomerates flocculated by the flocculant, which can reduce the friction between the agglomerates, thus significantly improving the fluidity of the solidified silt soil. At the same time, there are chemical bridge bonds between these films, which can enhance the structural stability of the solidified silt soil and improve the later strength.

[0032] In a further embodiment, the silt, cement, fly ash, acrylate emulsion, silica fume, chitosan quaternary ammonium salt, and powdered water reducer include the following parts by ratio: 250 - 500 parts of silt, 100 - 200 parts of cement, 1 - 50 parts of fly ash, 30 - 100 parts of acrylate emulsion, 1 - 60 parts of silica fume, 1 - 2 parts of chitosan quaternary ammonium salt, and 1 - 2 parts of powdered water reducer.

[0033] In a further embodiment, in order to avoid the problem of significant fluctuations in the properties of solidified silt due to the high variability of the silt properties, near-source and on-site resource utilization of silt can be achieved. In this embodiment, the physical and chemical properties of the silt are further analyzed, and corresponding component ratio adjustments are given as follows: The physical and chemical properties of the silt are determined by one or both of T-O type clay minerals or T-O-T type clay minerals; based on the physical and chemical properties of the silt, the ratio of the number of parts between cement and silica fume, and the ratio of the number of parts between cement and fly ash are determined. The crystal structure (T-O type or T-O-T type) of clay minerals in the silt directly affects its physical and chemical properties. T-O type clay minerals (such as kaolinite) are 1:1 layered structures with weak intermolecular forces, good thixotropy and fluidity, but insufficient water retention capacity; while T-O-T type clay minerals (such as montmorillonite) are 2:1 layered structures that can adsorb a large number of water molecules between layers, have a high specific surface area and strong flocculation ability, but poor thixotropy. If the curing agent ratio is not optimized for the mineral structure, the following problems will occur: When the T-O type is dominant: due to insufficient water retention capacity, the slurry is prone to segregation. It is necessary to add more silica fume with a high specific surface area to adsorb free water, and enhance water retention by generating C-S-H gel, while inhibiting the loss of fluidity; When the T-O-T type is dominant: due to excessive flocculation ability, the viscosity of the slurry increases. It is necessary to increase the amount of fly ash to utilize the "ball bearing effect" of its spherical particles to improve thixotropy, and regulate the hydration process through pozzolanic reactions; In the case of a mixture: it is necessary to coordinately regulate the ratio of silica fume and fly ash to balance water retention and thixotropy, and avoid performance deterioration caused by excessive single components.

[0034] It should be noted that natural clay minerals are widely distributed in nature. Their crystal structures are composed of silicon-oxygen tetrahedron layers and aluminum-oxygen octahedron layers arranged according to certain rules, and are divided into two major categories, 1:1 type and 2:1 type, according to the arrangement characteristics. The representative minerals are kaolinite and montmorillonite respectively. The 1:1 type is also called the T-O type, and the 2:1 type is also called the T-O-T type. The crystal structures and scanning electron microscope images of natural kaolinite and montmorillonite are as Figure 1 shown.

[0035] Combined with the above analysis of the components, when the physical and chemical properties of the silt are determined by T-O type clay minerals, the ratio of the number of parts of the cement and the silica fume is 1:(0.4 - 0.6); the ratio of the number of parts of the cement and the fly ash is 1:(0.01 - 0.2).

[0036] When the physical and chemical properties of the silt are determined by T-O-T type clay minerals, the ratio of the number of parts of the cement and the silica fume is 1:(0.01 - 0.2); the ratio of the number of parts of the cement and the fly ash is 1:(0.4 - 0.5).

[0037] When the physical and chemical properties of the sludge are jointly determined by T-O type clay minerals and T-O-T type clay minerals, the parts ratio of the cement to the silica fume is 1:(0.2 - 0.4); the parts ratio of the cement to the fly ash is 1:(0.2 - 0.4).

[0038] Example 2 This example takes 250 parts of sludge, 100 parts of cement, 10 parts of fly ash, 30 parts of acrylate emulsion, 50 parts of silica fume, 1.5 parts of chitosan quaternary ammonium salt and 1 part of powdered water reducer as examples, and discloses a preparation method of high-fluidity underwater non-dispersible high-performance solidified sludge soil, including the following steps: Step 1: Use 9 One of Si-nuclear magnetic resonance, X-ray total spectrum fitting or thermogravimetric analysis to determine whether the physical and chemical properties of the sludge are controlled by clay minerals (T-O type) with a 1:1 arrangement of silicon-oxygen tetrahedral layers and aluminum-oxygen octahedral layers or by clay minerals (T-O-T type) with a 2:1 arrangement. Further select the parts ratio between the cement and the silica fume and the parts ratio between the cement and the fly ash according to its physical and chemical properties with reference to the description in Example 1.

[0039] Step 2: Add deionized water to the chitosan quaternary ammonium salt to obtain a chitosan quaternary ammonium salt solution.

[0040] Step 3: Determine the parts ratio among the sludge, cement, silica fume and fly ash according to the physical and chemical properties in Step 1, weigh and mix them until uniform to obtain dry materials; Step 4: Mix and stir the dry materials obtained in Step 3 with the acrylate emulsion, and slowly add the powdered water reducer and the chitosan quaternary ammonium salt solution, and stir evenly until the cement has no agglomeration and meets the expected fluidity. For example, the stirring time is 20 - 30 minutes. Among them, the solid content of the acrylate emulsion is 30 - 50%. If the prepared solidified sludge soil needs to be used up within 5h, it is necessary to stop using it when large particle condensates appear inside the solidified sludge soil.

[0041] Furthermore, the preparation process of the chitosan quaternary ammonium salt solution in Step 2 includes: Weigh chitosan quaternary ammonium salt with a substitution degree greater than 90% and a molecular weight higher than 4.8×10 4 and add it to the reaction kettle, and add deionized water; the mass ratio of the chitosan quaternary ammonium salt to the deionized water is less than 1:3; Stir at a speed of 120 - 180 revolutions per minute at 75 - 90 °C until completely dissolved. Furthermore, the dosage of the chitosan quaternary ammonium salt solution is such that the concentration of chitosan quaternary ammonium salt in the liquid material is not less than 2.1 g / L.

[0042] Such as Figure 2As shown, the silt is composed of 73% quartz, 22% kaolinite, 4% muscovite and 1% dolomite, and its physical and chemical properties are mainly determined by T-O type clay minerals. Therefore, the ratio of cement to silica fume in the solidified silt should be between 1:0.4 and 0.6, and the ratio of cement to fly ash should be between 1:0.01 and 0.2.

[0043] Correspondingly, based on the above ratio and preparation method, the solidified silt is prepared, and its non-dispersibility is tested as Figure 3 shown. It can be seen that the solidified silt can be directly poured into the beaker, showing good fluidity. After the solidified silt is poured into the water, the water in the beaker does not immediately become turbid. The solidified silt settles in the beaker, and the settlement process is relatively slow and concentrated. The water body is slightly turbid after the solidified silt settles, but the overall turbidity is low, showing good non-dispersibility.

[0044] In this embodiment, the unconfined compressive strength, fluidity, and setting time of the mixture of the proportioned solidified silt are tested according to "Softening Curing Agent" CJ / T526-2018, "Test Methods for Standard Consistency Water Requirement, Setting Time and Soundness of Cement" GB / T1346-2011, and "Standard for Geotechnical Test Methods" GB / T 50123-2019. The test results are shown in Table 1, and all the measured parameters meet the design index requirements.

[0045] Table 1 Furthermore, in this embodiment, a corresponding comparative example is also given. If the T-O-T type ratio (cement: silica fume: fly ash = 1:0.1:0.4) is directly adopted without mineral analysis, it will cause segregation of the slurry, and the 28-day compressive strength is only 480 kPa and the fluidity is 390 mm. During the settlement process of the solidified soil, the water around it immediately becomes turbid, and the cement and soil particles are dispersed in the water, showing poor underwater non-dispersibility.

[0046] Example 3 High-fluidity underwater non-dispersible high-performance solidified silt, including the following parts of raw materials: silt, curing agent, coupling agent, flocculant and water reducer.

[0047] Specifically, the curing agent is P•O42.5 ordinary Portland cement and Class I fly ash. Cement can significantly enhance the mechanical properties of the solidified silt. The silicate gel generated by fly ash can fill the cracks and pores in the matrix. In addition, fly ash can also improve the thixotropy and fluidity of the fresh slurry, optimize the construction performance and ensure the later strength development of the solidified silt.

[0048] Specifically, the coupling agent is an acrylate emulsion with a solid content of 45%. The acrylate emulsion can form a continuous film between the particle aggregates flocculated by the flocculant, which can reduce the friction between aggregates, thus significantly improving the fluidity of the solidified dredged soil. At the same time, there are chemical bridge bonds between these films, which can enhance the structural stability of the solidified dredged soil and improve the later strength.

[0049] Specifically, the flocculant is silica powder and chitosan quaternary ammonium salt. Silica powder has high reactivity and specific surface area. Its high reactivity enables it to generate C-S-H gel with gelling properties, and its high specific surface area enables it to more effectively adsorb surrounding ions and molecules, forming flocs and thus improving the strength and stability of the solidified dredged soil in water. Due to its long-chain structure and easy becoming an electrolyte with a positive charge, chitosan quaternary ammonium salt plays multiple roles such as electro-neutralization, adhesion bridging and chelation on the negatively charged colloid system existing in the solidified sludge system, enhancing the non-dispersibility of the solidified dredged soil in water.

[0050] Specifically, the powdered water reducer can effectively improve the fluidity of the cement mortar, greatly improve the construction performance of the modified cement mortar, and have excellent underwater construction performance and working performance.

[0051] In this embodiment, the curing agent is P•O42.5 ordinary Portland cement and Class I fly ash, the coupling agent is an acrylate emulsion with a solid content of 45%, and the flocculant is silica powder and chitosan quaternary ammonium salt.

[0052] This embodiment discloses a preparation method of high-fluidity underwater non-dispersible high-performance solidified dredged soil with 250 parts of silt, 100 parts of cement, 40 parts of fly ash, 50 parts of acrylate emulsion, 3 parts of silica powder, 2 parts of chitosan quaternary ammonium salt and 1 part of powdered water reducer. The preparation method can refer to the steps in Embodiment 2, the difference is that the physical and chemical properties of the silt are mainly determined by T-O-T type clay minerals.

[0053] As Figure 4 shown, the silt is composed of 26% quartz, 40% illite, 21% montmorillonite and 13% feldspar, and its physical and chemical properties are mainly determined by T-O-T type clay minerals. Therefore, the ratio of cement to silica powder in the solidified dredged soil should be between 1:0.01 and 0.2, and the ratio of cement to fly ash should be between 1:0.4 and 0.5.

[0054] In this embodiment, the test effect of the underwater non-dispersibility of the solidified dredged soil mixture with this mix ratio is as Figure 5As shown, it can be seen that the solidified silt can be directly poured into the beaker, showing good fluidity. After the solidified silt is poured into water, the water in the beaker does not immediately become turbid. The solidified silt settles in the beaker, and the settling process is relatively slow and concentrated. The water is slightly turbid after the solidified silt settles, but the overall turbidity is low, showing good non-dispersibility.

[0055] In this embodiment, "Softening and Solidifying Agent" CJ / T 526-2018, "Test Methods for Standard Consistency Water Requirement, Setting Time and Soundness of Cement" GB / T 1346-2011, and "Geotechnical Test Methods Standard" GB / T 50123-2019 are used to test the unconfined compressive strength, fluidity, and setting time of the mixture of the proportioned solidified silt. The test results are shown in Table 2, and all the measured parameters meet the requirements of the designed indicators.

[0056] Table 2 Furthermore, in this embodiment, a corresponding comparative example is given. For the unanalyzed minerals, the T-O type ratio (cement: silica fume: fly ash = 1: 0.5: 0.1) is directly adopted. The viscosity of the slurry increases sharply, the fluidity is 80 mm, the 28-day strength is 550 kPa, and the underwater non-dispersibility is high.

[0057] Example 4 Taking 250 parts of silt, 100 parts of cement, 30 parts of fly ash, 40 parts of acrylate emulsion, 25 parts of silica fume, 2 parts of chitosan quaternary ammonium salt, and 1 part of powdered water reducer as an example, this embodiment discloses a preparation method of high-fluidity underwater non-dispersible high-performance solidified silt. The preparation method can refer to the steps in Example 2. The difference is that the physical and chemical properties of the silt are mainly determined by T-O type clay minerals and T-O-T type clay minerals. As Figure 6 shown, the silt is composed of 57% quartz, 16% montmorillonite, 15% kaolinite, and 12% feldspar, and its physical and chemical properties are mainly jointly determined by T-O type and T-O-T type clay minerals. Therefore, the ratio of cement to silica fume in the solidified silt should be between 1: 0.2 and 0.4, and the ratio of cement to fly ash should be between 1: 0.2 and 0.4.

[0058] In the example, the test effect of the underwater non-dispersibility of the mixture of the proportioned solidified silt is as Figure 7 shown. It can be seen that the solidified silt can be directly poured into the beaker, showing good fluidity. After the solidified silt is poured into water, the water in the beaker does not immediately become turbid. The solidified silt settles in the beaker, and the settling process is relatively slow and concentrated. The water is slightly turbid after the solidified silt settles, but the overall turbidity is low, showing good non-dispersibility.

[0059] In this embodiment, the unconfined compressive strength, fluidity and setting time of the mix ratio solidified silt soil mixture were tested using "Softening and Curing Agent" CJ / T526-2018, "Cement Standard Consistency Water Consumption, Setting Time and Stability Test Method" GB / T1346-2011 and "Geotechnical Test Method Standard" GB / T 50123-2019. The test results are shown in Table 3, and the measured parameters all meet the design index requirements.

[0060] Table 3 Furthermore, this embodiment gives a corresponding comparative example. In order to ensure underwater non-dispersibility, the prior art often blindly increases the amount of silica powder (cement: silica powder: fly ash = 1:0.6:0.1), which will lead to early cracking, 28d strength of only 580kPa, and fluidity of 140mm; the comparative example shows that when the curing agent ratio is mismatched with the silt mineral type, the compressive strength of the solidified body can drop by up to 30%, the fluidity loss exceeds 50%, and the underwater dispersibility is significantly deteriorated, which fully confirms the decisive role of ratio control based on mineral analysis in improving the comprehensive performance.

Claims

1. A high-fluidity underwater non-dispersible high-performance solidified silt soil, characterized in that It includes the following components: sludge, cement, fly ash, acrylate emulsion, silica fume, chitosan quaternary ammonium salt and powdered water reducer; Among them, the physical and chemical properties of the sludge are determined by one or both of T-O type clay minerals or T-O-T type clay minerals; based on the physical and chemical properties of the sludge, the parts ratio between cement and silica fume and the parts ratio between cement and fly ash are determined.

2. A highly fluid underwater non-dispersive high-performance solidified silt soil according to claim 1, characterized in that, When the physical and chemical properties of the sludge are determined by T-O type clay minerals, the parts ratio of the cement to the silica fume is 1:(0.4 - 0.6); The parts ratio of the cement to the fly ash is 1:(0.01 - 0.2).

3. A highly fluid underwater non-dispersible high-performance solidified silt soil according to claim 1, characterized in that When the physical and chemical properties of the sludge are determined by T-O-T type clay minerals, the parts ratio of the cement to the silica fume is 1:(0.01 - 0.2); The parts ratio of the cement to the fly ash is 1:(0.4 - 0.5).

4. A highly fluid underwater non-dispersible high-performance solidified silt soil according to claim 1, characterized in that, When the physical and chemical properties of the sludge are jointly determined by T-O type clay minerals and T-O-T type clay minerals, the parts ratio of the cement to the silica fume is 1:(0.2 - 0.4); The parts ratio of the cement to the fly ash is 1:(0.2 - 0.4).

5. A highly fluid underwater non-dispersive high-performance solidified silt soil according to claim 1, characterized in that, It includes the following components according to the parts ratio: 250 - 500 parts of sludge, 100 - 200 parts of cement, 1 - 50 parts of fly ash, 30 - 100 parts of acrylate emulsion, 1 - 60 parts of silica fume, 1 - 2 parts of chitosan quaternary ammonium salt and 1 - 2 parts of powdered water reducer.

6. A preparation method for preparing the highly flowable underwater non-dispersible high-performance solidified silt soil as described in any one of claims 1 to 5, characterized in that, It includes the following steps: Step 1: Determine the physical and chemical properties of the sludge; Step 2: Add deionized water to chitosan quaternary ammonium salt to obtain a chitosan quaternary ammonium salt solution; Step 3: According to the physical and chemical properties in Step 1, determine the parts ratio among the sludge, cement, silica fume and fly ash, weigh and mix them until uniform to obtain dry materials; Step 4: Mix and stir the dry materials obtained in Step 3 with acrylate emulsion, and slowly add powdered water reducer and chitosan quaternary ammonium salt solution, and stir well until the cement has no lumps and meets the expected fluidity.

7. The preparation method of the highly fluid underwater non-dispersible high-performance solidified silt soil according to claim 6, characterized in that, The physical and chemical properties in Step 1 are determined by one or both of T-O type clay minerals or T-O-T type clay minerals; Characterization and determination are carried out by the following methods: 29 One of Si-nuclear magnetic resonance, X-ray total spectrum fitting or thermogravimetric analysis.

8. The preparation method of the highly fluid underwater non-dispersible high-performance solidified silt soil according to claim 6, characterized in that, The preparation process of the chitosan quaternary ammonium salt solution in Step 2 includes: Weigh the chitosan quaternary ammonium salt with a degree of substitution greater than 90% and a molecular weight higher than 4.8×10 4 and add it to the reaction kettle, then add deionized water; the mass ratio of the chitosan quaternary ammonium salt to the deionized water is less than 1:3; Stir at a speed of 120 - 180 revolutions per minute at 75 - 90 °C until completely dissolved.

9. The preparation method of the highly fluid underwater non-dispersive high-performance solidified silt soil according to claim 6, characterized in that, The solid content of the acrylate emulsion is 30 - 50%.

10. The preparation method of the high-fluidity underwater non-dispersive high-performance solidified silt soil according to claim 6, characterized in that, The stirring duration in Step 4 is 20 - 30 minutes.

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