Maintenance-free high-performance silt composite solidifying agent and preparation method thereof

Abstract

The application discloses a kind of maintenance-free type silt composite curing agent and preparation method thereof, the curing agent takes 130-150 weight parts, water content 23%-27% of silt to be solidified as benchmark, by composite inorganic cementing matrix, active activation component, active mineral admixture, porous functional filler, high molecular thickening water-retention aid, deionized water, natural organic glue liquid and two-component waterborne epoxy modified liquid compound is formed.The curing agent proportion is reasonable, construction is simple, can be adapted to river dredging silt, municipal silt, engineering soft mud, curing effect is good, raw material does not contain heavy metal and toxic and harmful substance, environmental protection is excellent.Suiting process does not need to sprinkle water, temperature control and other special maintenance, the unconfined compressive strength of solidified silt 28d can reach more than 16MPa, system pH is long-term stable.The application overcomes the defects that traditional curing agent relies on special maintenance, process is complicated, solidified body is easy to shrink and crack, and there is environmental hidden danger, and widens the application of silt solidified soil in medium and high load engineering and ecological sensitive area.

Description

Technical Field

[0001] This invention relates to the fields of silt resource utilization and geotechnical engineering solidification materials, specifically to a maintenance-free silt composite solidifying agent and its preparation method. Background Technology

[0002] With rapid urbanization, the shortage of land for construction is becoming increasingly prominent. Coastal cities generally face insufficient land supply. Resource-based development of coastal mudflats without special ecological protection and control requirements is an important way to alleviate the land shortage. Coastal mudflats are formed by the near-shore deposition of sediment carried by ocean currents. The surface layer is covered with a thick layer of silt, and the soil is a typical soft soil foundation with low natural bearing capacity. Before developing the mudflats, it is necessary to complete the soft soil foundation reinforcement treatment and construct the working surface for construction equipment and on-site transportation roads.

[0003] Under the requirements of ecological sustainable development, the in-situ solidification process of low-pollution sludge is gradually replacing the traditional process of rock dumping and backfilling, becoming the mainstream technology for soft soil treatment in tidal flats. However, the existing direct solidification system of sludge still has technical shortcomings and is difficult to adapt to the construction material requirements of heavy-duty roads and equipment working surfaces in tidal flats. The core bottleneck is the insufficient compressive and shear mechanical properties of the solidified soil.

[0004] Existing patent CN107337410A discloses a type of silt solidification agent and a matching solidification process. The silt solidified soil prepared by this method has an unconfined compressive strength of about 1.5 MPa and a cohesion C of about 65 kPa after 28 days, which can slightly improve the mechanical properties of silt. However, there is still room for improvement in soil strength and shear resistance. Other existing patent technologies do not provide a solidification agent formulation system specifically adapted to high-strength solidified soil, nor do they propose a technical path to effectively improve the shear resistance of silt solidified soil.

[0005] Based on the shortcomings of existing technologies in terms of mechanical properties, this invention proposes a novel curing agent scheme to simultaneously improve the compressive strength and shear strength of silt-stabilized soil, thereby expanding the engineering application scenarios of silt-stabilized soil in tidal flats. Summary of the Invention

[0006] The purpose of this invention is to provide a maintenance-free composite sludge curing agent and its preparation method. Compared with traditional single cement-based sludge curing products, the curing agent provided by this invention can prepare cured soil with stable mechanical properties and good shrinkage resistance. This curing agent is suitable for various sludge conditions such as river channels, municipal works, and engineering soft mud. It can achieve stable curing of sludge with a moisture content of 23%~27%, with reasonable overall material ratio and simple construction process. The entire system does not contain heavy metals or toxic and harmful substances, and has good environmental performance. The sludge-cured soil prepared using this method can achieve an unconfined compressive strength of over 16MPa after 28 days, and the pH value of the system can remain stable for a long time. This invention solves the technical problems of traditional curing agents requiring special curing after molding, cumbersome construction procedures, easy shrinkage and cracking of the cured body, and environmental safety hazards. At the same time, it realizes maintenance-free green curing treatment of sludge, broadens the application range of sludge-cured soil in medium and high load projects and ecologically sensitive areas, and has significant technical and environmental value.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a maintenance-free high-performance sludge composite curing agent and its preparation method.

[0008] Preferably, based on 130-150 parts by weight of silt with a moisture content of 23%-27%, the amount of the composite inorganic cementitious matrix added is 55-85 parts by weight.

[0009] Preferably, the amount of the active activating component added is 3-5 parts by weight, which is used to regulate the hydration rate and stabilize the pH of the system.

[0010] Preferably, the active mineral admixture is added in an amount of 15-22 parts by weight, which can undergo a secondary hydration reaction under the action of the activating component, thereby improving the density and overall strength of the solidified body.

[0011] Preferably, the amount of the porous functional filler added is 18-27 parts by weight, which is used to adsorb free moisture, refine the pore structure, and improve the dimensional stability of the solidified body.

[0012] Preferably, the amount of the polymer thickening and water-retaining agent added is 1.5-2.0 parts by weight, which can prevent powder agglomeration, lock in system moisture, and improve the workability of materials.

[0013] Preferably, the deionized water is 12-16 parts by volume, the natural organic adhesive is 6-8 parts by volume, and the two-component waterborne epoxy modified liquid is 10-14 parts by volume.

[0014] Preferably, all raw materials used in this invention are green and environmentally friendly materials, free of heavy metals and toxic or harmful components, and the heavy metal leaching test results meet the current national environmental protection standards.

[0015] Preferably, the preparation method of the present invention does not require special curing operations such as watering, spraying, and constant temperature. It only needs to be sealed and left to stand at room temperature to complete the curing and molding.

[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: This maintenance-free high-performance sludge composite curing agent and its preparation method adopt an inorganic-organic composite synergistic system, eliminating the dependence of traditional products on specialized curing, significantly simplifying construction procedures, shortening construction period, and reducing overall construction costs. The natural organic adhesive enhances the interfacial adhesion of each component, improves the workability of the mixture, and inhibits shrinkage and cracking of the cured body; the two-component water-based epoxy modifier forms a dense organic network structure within the system, intercalating with inorganic hydration products, significantly improving the overall strength, toughness, and structural stability of the cured body. Under maintenance-free conditions, the 7-day compressive strength of the cured sludge consistently exceeds 12 MPa, exhibiting excellent mechanical properties; the entire formulation uses green, heavy metal-free raw materials, eliminating the risk of secondary pollution and making it suitable for a wide range of applications; the pH value and durability of the cured body are stable; simultaneously, a variety of raw materials can be selected and flexibly compounded and replaced, ensuring strong adaptability to industrial production and on-site construction.

[0017] Based on the technical principles, writing format, sentence logic, and professional expression style you provided, please write in accordance with the eight functional systems of this patent: **composite inorganic gel matrix, active activating component, active mineral admixture, porous functional filler, polymer thickening and water-retaining agent, natural organic adhesive, and two-component water-based epoxy modified liquid**. Please mark paragraph numbers, and ensure that the wording, sentence structure, and overall composition perfectly match the reference example. Furthermore, please objectively explain the mechanism of action of the formulation. Technical principle: The composite inorganic cementitious matrix undergoes a hydration reaction upon contact with water, generating hydration products such as CSH gel. This forms a basic cementing skeleton between silt particles, binding the loose silt particles together and transforming the originally highly fluid silt system into an overall structure with stable mechanical properties.

[0018] The active activating component can regulate the hydration reaction rate of the inorganic cementitious matrix, while stabilizing the pH of the system, creating a suitable environment for the secondary hydration reaction of the active mineral admixture, further replenishing the hydration cementitious products, and improving the overall density of the solidified body.

[0019] Under the action of the active activating components, the active mineral admixtures continuously undergo secondary hydration reactions, continuously generating cementitious substances that fill the internal pores of the system, further solidify the overall structure, and help the strength of the solidified body steadily increase with age.

[0020] Porous functional fillers have a well-developed pore structure, which can adsorb free water in the system, refine the internal pore structure of the solidified body, alleviate the volume shrinkage caused by water loss, improve the dimensional stability of the solidified soil, and reduce the generation of shrinkage cracks.

[0021] On the one hand, polymer thickeners and water-retaining agents can prevent the agglomeration of solid powders and improve the workability of mixtures; on the other hand, they can lock in the moisture inside the system, reduce the outward loss of moisture, and ensure that the cementitious components continue to hydrate in a sealed environment, achieving the effect of eliminating the need for external special curing.

[0022] Natural organic adhesives can enhance the interfacial bonding ability between sludge particles, inorganic hydration products, and various fillers, improve the interfacial bonding strength of each phase, inhibit the generation of interfacial defects, and further reduce the risk of cracking of the cured body.

[0023] After mixing, the two-component water-based epoxy modified liquid forms a continuous and dense organic network structure within the system, which interpenetrates with inorganic hydration products to construct an organic-inorganic interpenetrating composite structure, thereby improving the toughness and overall structural stability of the solidified body and further enhancing the mechanical properties of the solidified soil.

[0024] The present invention has the following advantages: Compared with traditional single cement-based sludge solidifying agents, this invention uses an inorganic-organic composite system, relying on a polymer thickening and water-retaining agent to lock in the internal moisture of the system. This eliminates the need for external special maintenance operations such as watering and temperature control, simplifying the on-site construction process. At the same time, it relies on continuous hydration to ensure a steady increase in the strength of the solidified body.

[0025] The present invention combines active activating components and active mineral admixtures, which can promote secondary hydration reaction in the system, continuously generate gel products, fill internal pores, improve the density of the solidified body, and effectively improve the problem of low overall strength of traditional solidified bodies.

[0026] This invention adds porous functional filler, which uses its porous structure to adsorb free water in the system, refines the internal pore structure, alleviates volume shrinkage caused by water loss, reduces the generation of shrinkage lines in the solidified body, and improves the dimensional stability of silt solidified soil.

[0027] This invention introduces a natural organic adhesive and a two-component waterborne epoxy modified liquid. The natural organic adhesive can enhance the interfacial bonding ability between various materials, while the waterborne epoxy modified liquid forms an organic network structure and intercalates with inorganic hydration products, thereby improving the toughness and structural integrity of the cured body and avoiding problems such as local loosening and cracking of the specimen.

[0028] This invention features a rationally proportioned raw material ratio, suitable for various working conditions such as river dredging silt, municipal silt, and engineering soft mud. It can achieve stable solidification of silt with a moisture content of 23%-27%. All raw materials are free of heavy metals and toxic or harmful substances, exhibiting excellent environmental friendliness. The solidified silt prepared using this method achieves an unconfined compressive strength of over 16 MPa at 28 days, and the pH value of the system remains stable over a long period. This invention solves the technical problems of traditional silt solidification agents, such as reliance on specialized curing, easy cracking of the solidified body, and environmental hazards, thus helping to expand the application range of solidified silt in medium- and high-load engineering projects and ecologically sensitive areas. Attached Figure Description

[0029] This application includes two accompanying figures: a process flow diagram and a performance comparison bar chart. Both figures are drawn with black and white lines, the lines are clear, and the annotations are standardized, conforming to patent drawing standards. A detailed explanation follows: Figure 1 Schematic diagram of the preparation process of maintenance-free sludge composite solidification agent This diagram illustrates the complete preparation process of the curing agent, outlining six major steps in the actual construction sequence: dry powder premixing, sludge mixing, phased water addition and stirring, addition of organic components, molding and vibration, and sealing and curing-free settling. The corresponding equipment for each step is also labeled. This process is tightly integrated and simple to operate, requiring only conventional mixing and vibration equipment. No special curing operations such as watering or temperature control are needed. This clearly demonstrates the core advantages of this invention: simplified construction process and room-temperature curing-free operation. It is suitable for both laboratory trials and large-scale on-site construction.

[0030] Figure 2 Bar chart comparing the compressive strength of each embodiment and comparative example at 3d, 7d, and 28d. The horizontal axis of this graph represents Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4, respectively, while the vertical axis represents compressive strength in MPa. The graph visually compares the mechanical properties of the composite curing agent of this invention with those of traditional single-cement systems, systems lacking functional components, and conventional commercial curing agents at three key ages: 3d, 7d, and 28d. The bar chart clearly shows that the compressive strength of the examples of this invention at each age is significantly higher than that of the various comparative examples, proving that this formulation, through multi-component compounding, can significantly improve the overall strength of silt-stabilized soil, and the comprehensive performance of the product is significantly superior to existing technologies. Detailed Implementation

[0031] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. The following examples are further illustrations of the content of the present invention, serving as explanations of the technical content of the present invention. However, the substantive content of the present invention is not limited to the examples described below. Those skilled in the art can and should know that simple variations or substitutions based on the essential spirit of the present invention should fall within the protection scope claimed by the present invention.

[0032] A maintenance-free sludge composite curing agent is formulated based on 130-150 parts by weight of sludge to be cured with a water content of 23%-27%. It consists of a composite inorganic cementitious matrix, an active activating component, active mineral admixtures, porous functional fillers, a polymer thickening and water-retaining agent, deionized water, natural organic adhesive, and a two-component water-based epoxy modifier. The proportions of each component are as follows: 55-85 parts by weight of composite inorganic cementitious matrix, 3-5 parts by weight of active activating component, 15-22 parts by weight of active mineral admixtures, 18-27 parts by weight of porous functional fillers, 1.5-2.0 parts by weight of polymer thickening and water-retaining agent, 12-16 parts by volume of deionized water, 6-8 parts by volume of natural organic adhesive, and 10-14 parts by volume of two-component water-based epoxy modifier. At room temperature (20-25℃), the converted densities of liquid materials are: 1.00 g / mL for deionized water, 1.02 g / mL for natural organic adhesive, and 1.05 g / mL for two-component waterborne epoxy modified liquid.

[0033] The composite inorganic cementitious matrix is ​​one or more of ordinary Portland cement, white Portland cement, and rapid-hardening Portland cement, and its overall performance meets the GB 175-2007 standard.

[0034] The ordinary silicate cement, white silicate cement, and rapid-hardening silicate cement shall have a strength grade of not less than P·O42.5 and a powder fineness of ≥320 mesh.

[0035] The active activating component is one or more of anhydrous gypsum, dihydrate gypsum, and hemihydrate gypsum, with a powder fineness ≥300 mesh and an effective calcium sulfate content ≥90%.

[0036] The active mineral admixture is one or more of granulated blast furnace slag powder, steel slag powder, and fly ash microspheres; the granulated blast furnace slag powder and steel slag powder have a fineness of ≥400 mesh, and the fly ash microspheres are Grade I ash with a fineness of ≥380 mesh.

[0037] The porous functional filler is an inorganic powder combination, selected from any combination of zeolite powder + limestone powder, zeolite powder + diatomite, or talc powder + diatomite. The overall fineness of the mixed powder is ≥350 mesh, and the porosity is ≥40%.

[0038] The polymer thickening and water-retaining agent is one or more of hydroxyethyl methylcellulose, hydroxypropyl methylcellulose, and methylcellulose, and its 2% aqueous solution has a viscosity of 15000-30000 mPa·s and is soluble in cold water at room temperature.

[0039] The deionized water has a conductivity of ≤5 μS / cm; the natural organic adhesive is one or more of glutinous rice adhesive, peach gum adhesive, and starch adhesive, with a solid content of 18%-22%, and is free from stratification and mold growth at room temperature.

[0040] The two-component waterborne epoxy modified liquid is one of the following: general-purpose two-component waterborne epoxy, modified acrylic epoxy composite liquid, and waterborne epoxy polyurethane composite liquid. Before use, components A and B are premixed evenly, with a solid content of 30%-35% and no volatile toxic solvents.

[0041] The silt to be solidified is any one of river dredging silt, municipal silt, or engineering soft mud. After pretreatment, the silt is sieved to a particle size of ≤5 mm, and stones and large debris are removed. The moisture content is strictly controlled between 23% and 27%.

[0042] All raw materials used in this invention are free of heavy metals and toxic or harmful substances. The heavy metal leaching index complies with GB 5085.3-2007, and the soil environmental index complies with GB 36600-2018. All indicators meet the current national environmental protection standards.

[0043] Furthermore, the solidified sludge of this invention is prepared using the preparation method provided by this patent. The specific working conditions and process parameters are as follows: the overall construction environment temperature is controlled at 10℃-35℃, the relative humidity is controlled at 40%-85%, and the optimal environment range is 20℃-25℃; the construction environment should avoid strong winds, direct sunlight, and rain immersion, and the molded specimens are sealed with plastic wrap.

[0044] Specific preparation steps: First, add the composite inorganic cementitious matrix, active activating component, active mineral admixture, porous functional filler, and polymer thickening and water-retaining agent to a dry powder mixer and stir at 30 r / min for 1.2-1.8 min until the powder is uniformly mixed and free of agglomerates. Second, add the pretreated sludge and stir at low speed for 0.5 min to break up sludge clumps. Third, add deionized water in two equal portions, adjust the mixer to 45 r / min, and stir for a total of 3.0-4.0 min. Fourth, add the natural organic adhesive and the premixed two-component water-based epoxy modified liquid sequentially, adjust the mixer to 20 r / min, and stir for 1.8-2.2 min. Fifth, after the material is loaded into the mold, in the laboratory, use a concrete vibrating table to vibrate at a frequency of 50 Hz for 20-30 s; on the construction site, use an immersion vibrator with an insertion point spacing ≤200 mm. mm, after vibration, scrape the surface of the specimen smooth; sixth step, seal the specimen with film, let it stand at room temperature, demold after 24 hours, and continue to stand naturally until the corresponding test age, without watering, spraying, temperature control or other special curing.

[0045] The unified testing conditions for this invention are as follows: ambient temperature 20-25℃, relative humidity 55%-70%, windless and protected from light; compressive strength testing follows GB / T 50081-2019, shrinkage testing follows GB / T 50082-2009, pH value is tested using the in-situ extraction method, and weather resistance is tested using a 6-month indoor natural aging test. The raw materials, proportions, and preparation processes used in Examples 1-9 and Comparative Examples 1-5 below all follow the above requirements.

[0046] 140 parts by weight of river dredging silt with a moisture content of 25%, 70 parts by weight of white silicate cement, 4.0 parts by weight of dihydrate gypsum, 18 parts by weight of granulated blast furnace slag powder, 22 parts by weight of zeolite powder and limestone powder composite filler, 1.7 parts by weight of hydroxyethyl methyl cellulose, 14 parts by volume of deionized water, 7 parts by volume of glutinous rice glue, and 12 parts by volume of general-purpose two-component water-based epoxy were selected. Sample preparation and curing were completed according to the above-mentioned process. Testing showed: 3-day compressive strength 9.2 MPa, 7-day compressive strength 13.6 MPa, 28-day compressive strength 16.8 MPa; 28-day shrinkage rate 0.021%; pH value: 7-day = 11.2, 28-day = 11.1, 6 months = 11.0; after 6 months of natural aging, the specimen surface showed no cracking or powdering, and the strength decay rate was <2%.

[0047] 130 parts by weight of municipal sludge with a moisture content of 23%, 55 parts by weight of ordinary silicate cement, 3 parts by weight of anhydrous gypsum, 15 parts by weight of ultrafine fly ash, 18 parts by weight of zeolite powder and diatomaceous earth composite filler, 1.5 parts by weight of hydroxypropyl methylcellulose, 12 parts by volume of deionized water, 6 parts by volume of modified starch adhesive, and 10 parts by volume of water-based epoxy-acrylic composite liquid were selected. Sample preparation and curing were completed according to the above preparation process. Testing showed: 3-day compressive strength 8.5 MPa, 7-day compressive strength 12.3 MPa, 28-day compressive strength 15.5 MPa; 28-day shrinkage rate 0.025%; pH value: 7-day = 11.3, 28-day = 11.2, 6 months = 11.1; after 6 months of natural aging, the specimens showed good appearance and a strength decay rate of <2.5%.

[0048] 150 parts by weight of engineering clay with a moisture content of 27%, 85 parts by weight of a composite cementitious matrix of white silicate cement and rapid-hardening silicate cement, 5 parts by weight of hemihydrate gypsum, 22 parts by weight of a composite admixture of granulated blast furnace slag powder and steel slag powder, 27 parts by weight of a composite filler of talc powder and diatomaceous earth, 2.0 parts by weight of methylcellulose, 16 parts by volume of deionized water, 8 parts by volume of gum arabic, and 14 parts by volume of waterborne epoxy-polyurethane composite liquid were selected. Sample preparation and curing were completed according to the above preparation process. Testing showed: 3-day compressive strength 9.8 MPa, 7-day compressive strength 14.1 MPa, 28-day compressive strength 17.5 MPa; 28-day shrinkage rate 0.019%; pH value: 7-day = 11.4, 28-day = 11.3, 6 months = 11.2; no cracking or powdering was observed after 6 months of natural aging, and the strength decay rate was <1.8%.

[0049] Comparative Example 1 140 parts by weight of silt with a moisture content of 25% were selected, and only 70 parts by weight of white silicate cement and 14 parts by volume of deionized water were added. All other components were removed. The preparation and settling conditions were the same as in Example 1. Testing showed: 3-day compressive strength 4.1 MPa, 7-day compressive strength 7.2 MPa, and 28-day compressive strength 9.5 MPa; 28-day shrinkage rate 0.087%, with obvious shrinkage cracks appearing on the surface of the specimen; the pH value of the system fluctuated by 0.8, indicating poor stability.

[0050] Comparative Example 2 The raw material ratio and preparation process were the same as in Example 1, except that the natural organic adhesive and the two-component water-based epoxy modifier were omitted. Testing revealed the following: 3-day compressive strength 5.8 MPa, 7-day compressive strength 9.1 MPa, 28-day compressive strength 11.2 MPa; 28-day shrinkage rate 0.052%. The mixture exhibited poor workability, and the specimens were locally loose.

[0051] Comparative Example 3 The raw material ratio and preparation process were the same as in Example 1, except that the active mineral admixtures and active activating components were removed. Testing revealed the following: 3-day compressive strength 5.2 MPa, 7-day compressive strength 8.5 MPa, 28-day compressive strength 10.3 MPa; 28-day shrinkage rate 0.061%, and fine shrinkage lines were observed on the specimen surface.

[0052] Comparative Example 4 A mainstream cement-based sludge curing agent was selected from the market. Sludge with the same moisture content was treated according to the product's recommended ratio. Standard industry-standard water curing was performed, with water spraying twice daily for 7 consecutive days. Other test conditions were the same as in Example 1. Testing revealed: 3-day compressive strength 6.3 MPa, 7-day compressive strength 10.1 MPa, 28-day compressive strength 12.4 MPa; 28-day shrinkage rate 0.043%. After water curing was discontinued, the strength increase slowed, and the specimens were prone to cracking in the later stages.

[0053] Comparative Example 5 Using the standard proportions and preparation process of Example 1, the ambient temperature was set to 5°C, while other test conditions remained unchanged. The 7-day compressive strength was measured to be 9.4 MPa, indicating that the low-temperature environment significantly reduced the hydration reaction rate of the system.

[0054] Processes and raw material characteristics not described in detail in this specification are all prior art known in the field. Modifications and equivalent substitutions made by those skilled in the art within the scope of the technical principles of this invention all fall within the protection scope of this invention.

Claims

1. A maintenance-free sludge composite curing agent, characterized in that: Based on 130-150 parts by weight of sludge to be solidified with a moisture content of 23%-27%, the proportions of each raw material component are as follows: 55-85 parts by weight of composite inorganic cementitious matrix, 3-5 parts by weight of active activating component, 15-22 parts by weight of active mineral admixture, 18-27 parts by weight of porous functional filler, 1.5-2.0 parts by weight of polymer thickening and water-retaining agent, 12-16 parts by volume of deionized water, 6-8 parts by volume of natural organic adhesive, and 10-14 parts by volume of two-component water-based epoxy modified liquid. All raw materials of the solidifying agent are free of heavy metals and toxic and harmful substances, and the heavy metal leaching index and soil environmental index meet the current national environmental protection standards. Under normal temperature (20-25℃), the converted densities of each liquid material are as follows: deionized water 1.00 g / mL, natural organic adhesive 1.02 g / mL, and two-component water-based epoxy modified liquid 1.05 g / mL.

2. The maintenance-free sludge composite solidifying agent according to claim 1, characterized in that: The composite inorganic cementitious matrix is ​​selected from one or more of ordinary Portland cement, white Portland cement, and rapid-hardening Portland cement, with a cement strength grade of not less than P·O 42.5, a powder fineness of ≥320 mesh, and all properties conforming to GB 175-2007 standard.

3. The maintenance-free sludge composite curing agent according to claim 1, characterized in that: The active activating component is selected from one or more of anhydrous gypsum, dihydrate gypsum, and hemihydrate gypsum, with a powder fineness ≥300 mesh and an effective calcium sulfate content ≥90%.

4. The maintenance-free sludge composite curing agent according to claim 1, characterized in that: The active mineral admixture is selected from one or more of granulated blast furnace slag powder, steel slag powder, and fly ash microspheres; wherein the granulated blast furnace slag powder and steel slag powder have a fineness of ≥400 mesh, and the fly ash microspheres are Grade I ash with a fineness of ≥380 mesh.

5. The maintenance-free sludge composite curing agent according to claim 1, characterized in that: The porous functional filler is an inorganic powder combination, selected from any one of zeolite powder + limestone powder, zeolite powder + diatomite, or talc powder + diatomite. The overall fineness of the mixed powder is ≥350 mesh, and the porosity is ≥40%.

6. The maintenance-free sludge composite solidifying agent according to claim 1, characterized in that: The polymer thickening and water-retaining agent is selected from one or more of hydroxyethyl methylcellulose, hydroxypropyl methylcellulose, and methylcellulose, and its 2% aqueous solution has a viscosity of 15,000 to 30,000 mPa·s and can be dissolved in cold water at room temperature.

7. The maintenance-free sludge composite curing agent according to claim 1, characterized in that: The natural organic adhesive is selected from one or more of glutinous rice adhesive, peach gum adhesive, and starch adhesive, with a solid content of 18% to 22%, and is free from stratification and mold growth at room temperature; the deionized water has a conductivity of ≤5 μS / cm; the two-component waterborne epoxy modified liquid is selected from one of general-purpose two-component waterborne epoxy, modified acrylic epoxy composite liquid, and waterborne epoxy polyurethane composite liquid, and components A and B need to be premixed evenly before use, with a solid content of 30% to 35%, and does not contain volatile toxic solvents.

8. The maintenance-free sludge composite curing agent according to claim 1, characterized in that: The silt to be solidified is any one of river dredging silt, municipal silt, or engineering soft mud. After pretreatment, the silt is sieved to a particle size of ≤5 mm, and stones and large debris are removed. The moisture content is strictly controlled to be 23% to 27%.

9. A method for preparing a maintenance-free sludge composite solidifying agent according to any one of claims 1 to 8, characterized in that: The process includes precise premixing of dry powder, initial mixing of sludge, mixing with water in stages, adding organic functional components, molding and vibration, and curing without maintenance. The specific parameters for each process are as follows: (1) Precise premixing of dry powder: All powder raw materials are put into a dry powder mixer and mixed at 30 r / min speed for 1.2 to 1.8 min until the powder is uniform and free of agglomerates; (2) Initial mixing of sludge: Pretreated sludge is added and mixed at low speed for 0.5 min to break up the lumps; (3) Mixing with water in stages: Deionized water is added in equal amounts in two stages and mixed at 45 r / min speed for 3.0 to 4.0 min; (4) Adding organic functional components: Natural organic adhesive and premixed two-component waterborne epoxy modified liquid are added in sequence and mixed at 20 r / min speed for 1.8 to 2.2 min; (5) Molding and vibration: In the laboratory, a 50 Hz concrete vibrating table is used for vibration for 20 to 30 s, and an immersion vibrator is used on the engineering site with an insertion point spacing of ≤200 mm. mm, after vibration, scrape the surface flat; (6) Curing without maintenance: the specimen is sealed and covered with film, and cured in an environment of 10℃~35℃ and relative humidity of 40%~85%. The optimal working condition is 20℃~25℃. After 24 hours, it is demolded. No special maintenance such as watering and temperature control is required throughout the process, avoiding strong wind, sun exposure and rain soaking environment.

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