High-performance curing material for curing sludge soil and use method of high-performance curing material
By using a composite system of red mud, quicklime, mineral powder, and cement, hydrated calcium silicate and hydrated calcium aluminate gels and ettringite are generated, solving the problems of high cost and environmental pollution in dredging sludge solidification. This achieves efficient and environmentally friendly sludge solidification, and is suitable for various engineering applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-17
- Publication Date
- 2026-03-31
AI Technical Summary
Existing technologies for solidifying dredged sludge have problems such as high cost, large carbon emissions, poor adaptability to sludge with high water content, weak erosion resistance of solidified soil, easy secondary softening, and low early strength. At the same time, the stockpiling of red mud and phosphogypsum occupies land and may cause pollution.
A composite system of red mud, quicklime, mineral powder and cement is adopted. Through the synergistic reaction of multiple components, calcium silicate hydrate and calcium aluminate hydrate gel are generated under the activation of quicklime. Combined with phosphogypsum to provide sulfate ions, a dense spatial network structure is formed, which activates the pozzolanic activity of mineral powder to generate ettringite, thereby improving the early strength and volume stability of the solidified body.
It achieves low-cost, high-performance sludge solidification, significantly improving the mechanical properties and erosion resistance of sludge. It is suitable for submarine tunnels, soft soil foundations, and dredged sludge solidification and repair projects, and effectively utilizes industrial solid waste to reduce carbon emissions.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of silt solidification materials technology, specifically relating to a high-performance solidification material for solidifying silt and its application method. Background Technology
[0002] River dredging, port construction, and coastal engineering projects generate large quantities of dredged silt with high water content, low strength, and high compressibility, posing a significant engineering challenge in its disposal and resource utilization. Traditional solidification methods primarily rely on cement, but these methods suffer from high costs, large carbon emissions, poor adaptability to silt with high water content, weak erosion resistance of the solidified soil leading to secondary softening, and low early strength with slow strength growth. Meanwhile, red mud, a byproduct of the alumina industry, accumulates in large quantities, and its strong alkalinity poses a potential environmental threat; phosphogypsum, a solid waste from wet-process phosphoric acid production, occupies large amounts of land and may cause phosphorus and fluorine pollution. Therefore, the efficient and environmentally friendly resource utilization of these large quantities of industrial solid wastes, and their application in dredged silt solidification, is of significant practical importance.
[0003] Red mud is a strongly alkaline waste residue from the alumina production process, rich in Fe2O3, Al2O3, and some active SiO2. However, it is highly alkaline and structurally stable, resulting in low activity when used alone. Phosphogypsum's main component is calcium sulfate dihydrate (CaSO4·2H2O), which can provide crucial sulfate ions (SO42-). 2- Mineral powder (granulated blast furnace slag) is a high-quality pozzolanic material with potential hydraulic properties, but its activity can only be activated in an alkaline environment. By synergistically combining these three materials and using quicklime for alkaline activation, the coupled utilization of multi-source solid waste and the improvement of its solidification performance can be achieved.
[0004] Therefore, the development of a composite material system for the synergistic solidification of red mud, quicklime, mineral powder, and cement is proposed. Utilizing its chemical properties, this system achieves efficient solidification, erosion resistance, and early strength while reducing cement content. Furthermore, it complements the initiation of pozzolanic reactions and the generation of expansive cementitious products, resulting in a low-cost, high-performance, and environmentally friendly novel sludge solidification material. This has significant engineering and environmental value. Summary of the Invention
[0005] To address the problems existing in the prior art, this invention provides a high-performance solidification material for solidifying silt and its application method. This solidification material exhibits rapid early strength development, good volume stability, excellent durability, and low cost. It can significantly improve the mechanical properties, structural stability, and erosion resistance of solidified silt, meeting the application requirements of submarine tunnels, soft soil foundations, and dredged silt solidification and repair projects. Furthermore, it fully utilizes industrial solid waste and effectively solidifies high-moisture-content dredged silt through multi-component synergistic reactions, significantly improving its mechanical properties and durability.
[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention discloses a high-performance solidification material for solidifying silt, comprising the following raw materials in parts by weight: 6-8 parts red mud, 6-8 parts mineral powder, 5-7 parts cement, 1-3 parts quicklime, and 2 parts phosphogypsum.
[0007] Furthermore, the cement is silicate cement; the red mud is sintered red mud with a pH value of 9-10.
[0008] Furthermore, the mineral powder is S95 grade blast furnace slag powder; the phosphogypsum is phosphogypsum that has been washed and dried.
[0009] Furthermore, the quicklime contains no less than 85% CaO.
[0010] In a second aspect, the present invention provides a method for using the aforementioned high-performance solidification material for solidified silt, comprising the following steps: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) The sieved red mud, mineral powder, cement and quicklime are dry-mixed to obtain a dry mixture of curing agent; (3) Add phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt. (4) Spread the high-performance solidification material of the solidified silt evenly on the surface of the original silt, and add water according to the water-solid ratio of 0.44 to make the high-performance solidification material of the solidified silt initially moisten the surface of the mud. (5) Stir the silt to ensure that the high-performance solidification material for solidifying the silt is evenly incorporated into the mud. (6) After step (5) is completed, spread the treated sludge evenly to form a uniform solidified surface layer and cure it.
[0011] Furthermore, in step (4), the mass ratio of the original silt to the high-performance solidification material of the solidified silt is 100:20~30.
[0012] Furthermore, step (6) involves curing under natural conditions, avoiding direct sunlight and rain, and covering the area with a film for the first 24 hours to prevent early water loss.
[0013] Furthermore, the operation time of steps (4) and (5) is controlled within 30 minutes to ensure the fluidity and uniformity of the reaction system; the material initially solidifies within 12 hours at room temperature, reaches demoldable strength in 2 days, and reaches design strength in 28 days.
[0014] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: (1) This invention employs a composite system of red mud, quicklime, mineral powder, and cement. Red mud and mineral powder serve as the main pozzolanic active materials, which are activated in an alkaline environment. Their active SiO2 and Al2O3 react with Ca(OH)2 to generate a large amount of hydrated calcium silicate and hydrated calcium aluminate gel, which together with ettringite form a dense spatial network structure to achieve high-strength curing. Phosphogypsum serves as a key sulfate activator, providing a large amount of SO42. - Al³⁺ is released during the hydration of cement, red mud, and mineral powder in an alkaline environment. + and Ca² + The reaction produces a large amount of needle-like ettringite; the strong alkaline environment provided by quicklime and cement rapidly activates the pozzolanic activity of the mineral powder, while cement hydration generates CSH gel to provide initial strength, with controllable initial setting time and minimal system shrinkage; quicklime (CaO) reacts rapidly with water to form hydrated lime (Ca(OH)2), causing the pH of the system to rise sharply to above 12, and the reaction with water consumes a large amount of water and releases heat, which can quickly reduce the water content of the sludge and initially improve its physical state; the Ca²⁺ released by the mineral powder during the later hydration process... + With SiO4 4- It participates in the formation of more C–S–H gels, significantly improving the later strength and volume stability of the solidified body; at the same time, it improves the interfacial bonding performance between the solidified body and the original sludge, resulting in better overall structure after solidification.
[0015] (2) This invention uses industrial solid waste such as red mud, phosphogypsum, and mineral powder as the main components to replace part of the cement, which not only reduces the carbon emissions of the solidification system, but also realizes the high-value utilization of industrial by-products, and has good ecological and environmental benefits and economic promotion value; in addition, the solidification material of this invention has good fluidity in the initial stage, and can be uniformly mixed in silt with high water content without serious bleeding or stratification; it is suitable for in-situ solidification and repair projects of silt under various complex environmental conditions such as submarine tunnels, river dredging, and soft foundation reinforcement. Detailed Implementation
[0016] The present invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods not specifically described in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.
[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. All reagents and materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions.
[0018] In the following embodiments, the cement is silicate cement, and its composition is shown in Table 1 below; the red mud is sintered red mud with a pH value of 10, and its composition is shown in Table 2 below; the quicklime has the composition shown in Table 3 below; the mineral powder is S95 grade blast furnace slag powder, and its composition is shown in Table 4 below; the phosphogypsum is phosphogypsum that has been washed and dried. In the following embodiments, the parts mentioned are parts by weight.
[0019] Table 1 Main Components of Silicate Cement Table 2 Main Components of Red Mud Table 3. Main Components of Quicklime Table 4 Main Components of Mineral Powder
[0020] Example 1 Preparation of high-performance curing materials: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) Mix 6 parts of sieved red mud, 6 parts of mineral powder, 5 parts of cement and 1 part of quicklime dry to obtain a dry mixture of curing agent; (3) Add 2 parts of phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt.
[0021] Example 2 Preparation of high-performance curing materials: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) Mix 6 parts of sieved red mud, 7 parts of mineral powder, 6 parts of cement and 2 parts of quicklime dry to obtain a dry mixture of curing agent; (3) Add 2 parts of phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt.
[0022] Example 3 Preparation of high-performance curing materials: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) Mix 6 parts of sieved red mud, 8 parts of mineral powder, 7 parts of cement and 3 parts of quicklime dry to obtain a dry mixture of curing agent; (3) Add 2 parts of phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt.
[0023] Example 4 Preparation of high-performance curing materials: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) Mix 7 parts of sieved red mud, 6 parts of mineral powder, 5 parts of cement and 3 parts of quicklime dry to obtain a dry mixture of curing agent; (3) Add 2 parts of phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt.
[0024] Example 5 Preparation of high-performance curing materials: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) Mix 7 parts of sieved red mud, 7 parts of mineral powder, 6 parts of cement and 1 part of quicklime dry to obtain a dry mixture of curing agent; (3) Add 2 parts of phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt.
[0025] Example 6 Preparation of high-performance curing materials: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) Mix 7 parts of sieved red mud, 8 parts of mineral powder, 7 parts of cement and 2 parts of quicklime dry to obtain a dry mixture of curing agent; (3) Add 2 parts of phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt.
[0026] Example 7 Preparation of high-performance curing materials: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) Mix 8 parts of sieved red mud, 6 parts of mineral powder, 5 parts of cement and 2 parts of quicklime dry to obtain a dry mixture of curing agent; (3) Add 2 parts of phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt.
[0027] Example 8 Preparation of high-performance curing materials: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) Mix 8 parts of sieved red mud, 7 parts of mineral powder, 6 parts of cement and 3 parts of quicklime dry to obtain a dry mixture of curing agent; (3) Add 2 parts of phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt.
[0028] Example 9 Preparation of high-performance curing materials: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) Mix 8 parts of sieved red mud, 8 parts of mineral powder, 7 parts of cement and 1 part of quicklime dry to obtain a dry mixture of curing agent; (3) Add 2 parts of phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt.
[0029] Example 10 Experimental site: Undiscovered silt test silt is high water content cohesive silt (soil), with a natural water content of about 45%, has soft plasticity, low strength, strong susceptibility to disturbance, and has typical soft soil engineering properties; (1) The high-performance solidification materials of solidified silt prepared in Examples 1 to 9 were evenly spread on the surface of the original silt (the amount of solidification agent and the proportion of silt to be treated are shown in Table 5 below), and water was added according to the water-solid ratio of 0.44 to make the high-performance solidification materials of solidified silt initially moisten the surface of the mud. Table 5. Ratio of high-performance solidification material to silt to be treated for solidifying silt. (5) Stir the silt to ensure that the high-performance solidification material for solidifying the silt is evenly incorporated into the mud. (6) After the mixing in step (5), the treated sludge is spread and leveled to form a uniform solidified surface layer. It is then cured under natural conditions on site, avoiding direct sunlight and rain. A thin film is used to cover the sludge for the first 24 hours to prevent early water loss. The original sludge layer shows obvious surface hardening after 24 hours of solidification treatment, and the mud surface no longer settles when stepped on. After 7 days of curing, the solidified layer forms a relatively complete structural skeleton with significant strength increase. After 28 days, the solidified layer is dense and uniform, without cracking or peeling, and has good resistance to disturbance and durability. At the curing ages of 7 days and 28 days, surface penetration resistance tests and on-site sampling are conducted on the solidified area to evaluate the strength increase and structural stability of the solidified surface layer. The compressive strength of the solidified surface layer at the curing ages of 7 days and 28 days is shown in Table 6. Table 6 Compressive Strength of Cured Surface Layer (MPa) As shown in Table 5, the high-performance solidification material for silt prepared by this invention can significantly improve the engineering properties of undisturbed dredged silt, forming a solidified surface layer with stable bearing capacity. It is suitable for applications such as silt disposal site treatment, construction site leveling, and soft soil foundation reinforcement. Furthermore, laboratory testing of soil samples taken from the solidified area showed that their 7-day and 28-day unconfined compressive strengths were 1.78 MPa and 3.64 MPa, respectively, both conforming to the expected growth pattern, further verifying the reliability and effectiveness of the solidification system of this invention.
[0030] In this invention, the red mud is rich in active alumina and silica, which can be activated in an alkaline environment to participate in the pozzolanic reaction, generating C–A–S–H (calcium aluminum silicate hydrate) products with gel properties, thereby improving the overall strength of the solidified body. The potential hydration activity of the mineral powder can be further activated after the cement hydration produces Ca(OH)2, forming C–S–H (calcium silicate hydrate) gel, which helps to improve the later strength and optimize the density of the solidified body. The addition of silicate cement provides the necessary early structural framework for the solidification system. By generating a large amount of C–S–H gel and microcrystalline structure, the solidified body can have a certain load-bearing capacity in the early stage of forming. The incorporation of quicklime increases the alkalinity of the mud, promoting further reaction of the active components in the red mud and mineral powder. Phosphogypsum can provide a stable source of sulfate ions for the system, making the needle-like AFt (ettringite) structure generated during the solidification process more abundant, enhancing the volume stability and crack resistance of the solidified body.
[0031] Overall, the multi-component solidification system (high-performance solidification material for solidifying silt) adopted in this invention can form a composite structure of multiphase hydration products and mineral gel in the early stage, which significantly improves the compactness, impermeability and molding stability of the solidified silt. As the curing period is extended, the volcanic ash reaction and potential active reaction continue, the strength of the solidified body continues to increase, and finally a dense and uniform solidified structure with no obvious cracks, good durability and erosion resistance is obtained, which meets the performance requirements of dredged silt solidification and engineering backfilling.
[0032] The high-performance solidification material for silt, based on red mud, mineral powder, silicate cement, quicklime, and phosphogypsum, proposed in this invention significantly improves the engineering performance of dredged silt with high water content, exhibiting good early-stage formability, strength growth, and volume stability. The technical solution and implementation methods of this invention have been described in detail above, and the application effects have been illustrated with specific formulation examples. These examples are only used to help understand the core technical ideas of this invention. For those skilled in the art, without departing from the basic concept of this invention, the component ratio, dosage, or operation method of the solidification material can be appropriately adjusted according to actual engineering needs. Therefore, the content of this specification should not be construed as limiting the scope of protection of this invention.
Claims
1. A high-performance solidification material for solidifying silt, characterized in that, The high-performance solidification material for solidified silt includes the following raw materials in parts by weight: 6-8 parts red mud, 6-8 parts mineral powder, 5-7 parts cement, 1-3 parts quicklime, and 2 parts phosphogypsum.
2. The high-performance solidification material for solidifying silt according to claim 1, characterized in that, The cement is silicate cement; the red mud is sintered red mud with a pH value of 9-10.
3. The high-performance solidification material for solidifying silt according to claim 1, characterized in that, The mineral powder is S95 grade blast furnace slag powder; the phosphogypsum is phosphogypsum that has been washed and dried.
4. The high-performance solidification material for solidifying silt according to claim 1, characterized in that, The quicklime has a CaO content of not less than 85%.
5. A method of using the high-performance solidification material for solidifying silt as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Dry the red mud, phosphogypsum, mineral powder, cement and quicklime to constant weight and pass them through a 100-mesh sieve; (2) The sieved red mud, mineral powder, cement and quicklime are dry-mixed to obtain a dry mixture of curing agent; (3) Add phosphogypsum to the dry mixture of curing agent and mix until uniform to obtain a high-performance curing material for curing silt. (4) Spread the high-performance solidification material of the solidified silt evenly on the surface of the original silt, and add water according to the water-solid ratio of 0.44 to make the high-performance solidification material of the solidified silt initially moisten the surface of the mud. (5) Stir the silt to ensure that the high-performance solidification material for solidifying the silt is evenly incorporated into the mud. (6) After step (5) is completed, spread the treated sludge evenly to form a uniform solidified surface layer and cure it.
6. The method of using the high-performance solidification material for solidifying silt according to claim 5, characterized in that, In step (4), the mass ratio of the original silt to the high-performance solidification material of the solidified silt is 100:20~30.
7. The method of using the high-performance solidification material for solidifying silt according to claim 5, characterized in that, Step (6) Cultivate under natural conditions, avoiding direct sunlight and rain. Cover with film for the first 24 hours to prevent early water loss.
8. The method of using the high-performance solidification material for solidifying silt according to claim 5, characterized in that, The operation time for steps (4) and (5) should be controlled within 30 minutes.