A dredged sand solidification product and a dredged sand solidification treatment method

Abstract

The application discloses a kind of dredged sand solidification products and dredged sand solidification processing methods.The solidification product includes inorganic binder obtained by mixing solidification agent, water and aggregate, the weight fraction of each component in the inorganic binder is 10 parts of solidification agent, 6 parts~10 parts of water, 35 parts~41 parts of molecule, 10 parts~15 parts of melon seed piece, 20 parts~30 parts of dredged sand and 20 parts~25 parts of stone chip, which is compacted and formed and demoulded to obtain;The solidification processing method is obtained by grading matching, mixing, compaction forming and demoulding and curing;Advantages are: by setting different grading gravel, dredged sand and multi-level aggregate system of stone chip, form a reasonable grading structure, so that coarse aggregate forms a skeleton support, fine aggregate fills the pore, improves the overall material density;At the same time, cooperate with the cementing effect of solid waste base solidification agent, 7d unconfined compressive strength can be obtained under the condition of lower water-binder ratio, meet the use requirements of road base or cushion engineering.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering and dredged sand resource utilization technology, and in particular relates to a dredged sand solidification product and a dredged sand solidification treatment method. Background Technology

[0002] With the continuous expansion of river dredging, port dredging, and waterway maintenance projects, a large amount of dredged sand has been generated. Dredged sand has fine particles, unreasonable gradation, and a high mud content; direct stockpiling not only occupies land resources but also easily causes environmental pollution. Therefore, how to achieve the resource utilization of dredged sand has become an urgent problem to be solved in the fields of civil engineering and solid waste utilization. In road engineering, base or subbase materials typically adopt structural forms such as graded crushed stone and cement-stabilized crushed stone to meet the requirements of load-bearing capacity and durability. However, dredged sand has a simple particle gradation and a small fineness modulus. When directly used as road base material, it suffers from insufficient structural density, low compressive strength, and poor water resistance, making it difficult to meet the requirements of engineering use.

[0003] In existing technologies, dredged sand is typically modified by adding cement or other inorganic curing agents to improve its mechanical properties. However, current mix proportions are mostly determined empirically, failing to fully consider the synergistic effect of coarse and fine aggregate gradation, leading to instability in the material structure. Furthermore, some schemes increase the amount of cementitious materials to ensure strength, which, while improving early strength, results in higher material costs and hinders large-scale engineering applications. In addition, the utilization of by-products such as recycled aggregates or stone chips is limited, indicating room for improvement in resource utilization efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a low-cost, high-strength dredged sand solidification material and its treatment method.

[0005] To solve the above-mentioned technical problems, the dredged sand solidification product of the present invention includes an inorganic binder obtained by mixing a curing agent, water and aggregate. The inorganic binder comprises 10 parts by weight of curing agent, 6 to 10 parts by weight of water, 35 to 41 parts by weight of molecules, 10 to 15 parts by weight of sunflower seed chips, 20 to 30 parts by weight of dredged sand and 20 to 25 parts by weight of stone chips, which are then compacted and demolded.

[0006] The molecules are crushed stone with a particle size range of 16mm-31.5mm.

[0007] The sunflower seed chips are crushed stone with a particle size range of 5-16mm; the stone chips are crushed stone with a particle size range of 0-5mm.

[0008] The dimensionless fineness modulus of the dredged sand is in the range of 0.5-0.7.

[0009] The curing agent is a solid waste-based curing agent, which includes 50 parts by weight of steel slag, 30 parts by weight of furnace slag, and 20 parts by weight of composite gypsum. The composite gypsum includes 12 parts by weight of power plant gypsum and 8 parts by weight of titanium gypsum.

[0010] Dredging Sand Solidification Treatment Method Includes the following steps: A. Gradation Fitting: The curing agent, water and aggregate are mixed to obtain an inorganic binder. The inorganic binder consists of 10 parts by weight of curing agent, 6 to 10 parts of water, 35 to 41 parts of crushed stone with a particle size range of 16 mm to 31.5 mm, 10 to 15 parts of crushed stone with a particle size range of 5 to 16 mm, 20 to 30 parts of dredged sand with a fineness modulus range of 0.5 to 0.7, and 20 to 25 parts of stone chips. B. Mixing: The sample is obtained by uniform mechanical mixing under the conditions of a temperature range of 15℃~25℃ and a relative humidity range of 50%~60%. C. Compaction and demolding: Place the sample on the press and press it into the mold at a rate of 1 mm / min. The pressure peak during the pressing process shall not exceed 400kN. After the sample is fully pressed into the mold, hold the pressure and let it stand before demolding to obtain the specimen and prepare it for curing. D. Curing: The specimens were cured for more than 4 days, and were immersed in water for curing on the last day.

[0011] The dimensionless fineness modulus of the dredged sand is in the range of 0.5-0.7.

[0012] The stone chips are crushed stone with a particle size range of 0-5mm.

[0013] The curing agent is a solid waste-based curing agent, which includes 50 parts by weight of steel slag, 30 parts by weight of furnace slag, and 20 parts by weight of composite gypsum. The composite gypsum includes 12 parts by weight of power plant gypsum and 8 parts by weight of titanium gypsum.

[0014] The specimens were first cured in a standard curing chamber at a temperature of 19℃ to 21℃ and a relative humidity of ≥95%. The last day was spent on immersion curing, in which the specimens were sealed and immersed in water at a temperature of 18℃ to 22℃ for 24 hours.

[0015] Advantages of this invention: 1. By setting up a multi-grade aggregate system of 16mm-31.5mm graded crushed stone, 5mm-16mm graded crushed stone, dredged sand and stone chips, a reasonable gradation structure is formed, so that the coarse aggregate forms a skeleton support and the fine aggregate fills the pores, thereby improving the overall density of the material; at the same time, with the cementing effect of solid waste-based solidifying agent, a high 7d unconfined compressive strength can be obtained under low water-cement ratio conditions, which meets the requirements for use in road base or subbase engineering. 2. Replacing some traditional cementitious materials with solid waste-based solidifying agents with steel slag, furnace slag and composite gypsum as the main components not only reduces material costs, but also realizes the high-value utilization of industrial solid waste. At the same time, dredged sand is used as the main fine aggregate and is utilized as a resource, effectively reducing the amount of waste, which has good economic and environmental benefits. 3. By controlling the compaction pressure, loading rate, and curing regime, the internal structure formation process of the material is optimized, making the cured body structure uniform and stable, improving the water stability and durability of the cured product, and making it suitable for structural parts such as base courses or subbases in road engineering. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a diagram illustrating the baseline proportions for verification of the present invention. Figure 3 The compressive strength of the natural curing agent of this invention; Figure 4 The compressive strength of the solid waste-based solidifying agent of this invention; Figure 5 The compressive strength of the five curing agents of this invention at a 20% admixture of dredged sand is measured. Detailed Implementation

[0017] The dredged sand solidification product and dredged sand solidification treatment method of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example

[0018] The dredged sand solidification product comprises 3.5 kg of solid waste-based solidifying agent, 2.3 kg of water, and aggregate mixed together. The aggregate includes 12.25 kg of polymer, 5.25 kg of crushed sand, 10.5 kg of dredged sand, and 7 kg of stone chips. The mixture is obtained by compaction and demolding. The average compressive strength obtained from the compressive strength test is 12.06 MPa. Example

[0019] A. Grading Fitting: This includes an inorganic binder obtained by mixing 10 parts by weight of solid waste-based solidifying agent, 6.5 parts by weight of water, and aggregates. The aggregates include 35 parts by weight of graded crushed stone (molecular) with a particle size range of 16mm-31.5mm, 15 parts by weight of graded crushed stone (fragmented stone) with a particle size range of 5-16mm, 30 parts by weight of dredged sand with a fineness modulus range of 0.5-0.7, and 20 parts by weight of stone chips (graded crushed stone with a particle size range of 0-5mm). B. Mixing: Take 12.25 kg of molecule, 5.25 kg of sunflower seed chips, 7 kg of stone chips, 10.5 kg of dredged sand, 3.5 kg of solid waste-based solidifying agent and 2.3 kg of water and mix them to obtain the sample. Under the conditions of 20℃ temperature and relative humidity ≥50%, mechanical mixing is carried out using a 60L type forced mixer for more than 60 seconds to ensure uniformity. C. Compaction and Demolding: Weigh the well-stirred sample and load it into a 150mm*150mm unconfined compression mold. Place the mold on the press and adjust its centering. Apply pressure at 1 mm / min until the upper and lower pressure columns are fully pressed into the mold. The pressure peak during the pressing process should not exceed 400kN. After the pressure columns are fully pressed into the mold, stop loading and maintain the pressure for 2 minutes. After the pressure is maintained, release the pressure and remove the mold. Let it stand for more than 6 hours before demolding to obtain the specimen. When demolding, place the specimen on the release agent demolding platform, adjust its centering, and start the machine to complete the demolding. After demolding, number the specimen, seal it, and prepare it for curing. D. Curing: The curing cycle of the specimens is 7 days, of which 6 days are standard curing in a standard curing chamber at a curing temperature of 20℃ and a relative humidity of ≥95%, and the last day is water immersion curing, in which the specimens are sealed and immersed in water at a temperature range of 20℃±2℃ for 24 hours. E. Compression Test: After the curing period, remove the specimen from the water, wipe it clean, and let it air dry until it is saturated and surface dry before starting the compression test. Observe the specimen for any damage. If the damaged area is <10%, that is, no damage or slight damage, the test continues. If the damaged area is ≥10%, that is, severe damage, the compression test is not performed. Place the specimen on the platform of the compression testing machine and start applying pressure at a rate of 1 mm / min until the specimen breaks. Record the maximum load and calculate the compressive strength.

[0020] Regarding the gradation fitting test, the proportioning scheme of aggregates such as dredged sand and crushed stone with inorganic binders (cement and curing agent) was studied. By optimizing the gradation design, adjusting the type and dosage of adhesives, verifying the feasibility of recycled aggregates, and evaluating the influence of different proportions on the 7-day unconfined compressive strength.

[0021] Experimental materials and physical parameters: I. Key Achievements in Gradation Design Sand gradation optimization: The fineness modulus was adjusted to 2.11–3.27 by using the synthesis curves of materials A, B, and C, so that the synthesis curve was close to the median value of the gradation (2.69).

[0022] Grating fit of aggregate: The mixed aggregate of "gravel:stone chips:dredged sand = 35%:30%:35%" (the "gradation black" curve in the figure) was successfully fitted to the specification requirements (upper / lower limit), providing a basis for mix ratio 1; wherein the particle size range of the molecules is 16mm-31.5mm graded crushed stone, the particle size range of the gravel is 5-16mm graded crushed stone, and the dimensionless fineness modulus range of the dredged sand is 0.5-0.7.

[0023] II. Detailed description of the experimental process (a) First stage: such as Figure 2 As shown, the benchmark ratio verification

[0024] (ii) Second stage: such as Figure 3 As shown, parameter optimization 1. Study on the influence of sand ratio The proportion of coarse aggregate is fixed (molecule: gravel: stone chips = 1:0.35:0.63), the bulk density is 2340 kg / m³, the amount of curing agent is 5%, and the proportion of dredged sand is adjusted (25%–40%).

[0025]

[0026] Conclusion: The strength is optimal when the sand ratio is 25%, while excessively high sand ratios weaken the skeleton effect.

[0027] 2. Research on alternatives to solid waste solidification agents, such as... Figure 4 As shown

[0028] Conclusion: Under the same sand ratio, solid waste-based solidifiers generally have higher strength than natural solidifiers, and are more economical, environmentally friendly, and have stable performance.

[0029] 3. Confirm the optimal parameters, such as Figure 5 As shown Based on the above experiments, we found that the specimen strength is inversely proportional to the amount of dredged sand added; the higher the amount of dredged sand, the lower the specimen strength. Therefore, we reduced the amount of dredged sand to 20%, changed the type of curing agent, and conducted comparative tests. The test results are as follows.

[0030]

[0031] The solid waste-based solidifying agent consists of: steel slag: 50%, furnace slag: 30%, and composite gypsum: 20%, of which power plant gypsum: 12% and titanium gypsum: 8%. Traditional natural material curing agent: Ordinary Portland cement (PO 42.5R): 50%, Water-quenched blast furnace slag (S95 grade): 30%, Power plant fly ash (F class I grade): 20%, Admixtures: Sodium sulfate (early strength agent): 1.0%, Polycarboxylate superplasticizer: 0.8%, UEA expansion agent: 6-8%, Water-cement ratio (W / B): ≈ 0.30; Self-prepared curing agent: 25% P.O42.5 cement, 25% S95 granulated blast furnace slag powder, 35% Grade 2 fly ash, 15% desulfurized gypsum; The cement type is P.O42.5 cement.

[0032] When the dredged sand content is 20%, the solid waste solidification agent strength reaches 7.91 MPa, providing a benchmark for subsequent recycled aggregate tests.

[0033] Gradation design is the core: the strength of mix ratio 1 (mixed aggregate) (12.06 MPa) far exceeds that of pure dredged sand (2.07 MPa), proving that reasonable gradation is the key to improving strength.

[0034] The curing agent has obvious advantages: at the same dosage, the strength of the curing agent group is generally higher than that of the cement group (e.g., 10.30 MPa vs 8.16 MPa in mix proportion 0).

[0035] Feasibility of recycled aggregates: The strength of recycled aggregates reaches 6.67 MPa, which fully meets the engineering requirements and provides a way to reduce costs.

[0036] Highly sensitive to sand ratio: The proportion of dredged sand needs to be controlled at 20%–25%. Too high a proportion will lead to a loose skeleton and reduced strength.

[0037] Economic and environmental balance: The successful application of solid waste solidification agents and recycled aggregates combines performance and sustainability.

[0038] Recommended mix ratio 1: Aggregate (35% molecular weight + 15% dried seed powder + 20%–25% dredged sand + 20% stone chips) + 10% solid waste solidification agent + 6%–10% water.

[0039] Expected strength: The 7-day strength can reach 12 MPa, and the 28-day strength is expected to be further improved.

[0040] Engineering application recommendations: Dredged sand should be used in combination with coarse aggregate to avoid insufficient strength of a single material; curing agents can replace cement, reducing costs and improving performance; recycled aggregates can partially replace natural aggregates and are suitable for non-load-bearing structures.

[0041] This experiment, through system gradation design and parameter optimization, clarified the optimal proportion (20%–25%) of dredged sand in the mixed aggregate, verified the engineering value of solidifier and recycled aggregate, and provided a technically reliable and economically reasonable solution for the resource utilization of dredged sand.

Claims

1. A dredged sand solidification product, characterized in that, The inorganic binder is obtained by mixing a curing agent, water and aggregate. The inorganic binder consists of 10 parts curing agent, 6 to 10 parts water, 35 to 41 parts water, 10 to 15 parts water flakes, 20 to 30 parts dredged sand and 20 to 25 parts stone chips by weight, which are then compacted and demolded.

2. The dredged sand solidification product according to claim 1, characterized in that: The molecules are crushed stone with a particle size range of 16mm-31.5mm.

3. The dredged sand solidification product according to claim 1, characterized in that: The sunflower seed chips are crushed stone with a particle size range of 5-16mm; the stone chips are crushed stone with a particle size range of 0-5mm.

4. The dredged sand solidification product according to claim 1, characterized in that: The dimensionless fineness modulus of the dredged sand is in the range of 0.5-0.

7.

5. The dredged sand solidification product according to claim 1, characterized in that: The curing agent is a solid waste-based curing agent, which includes 50 parts by weight of steel slag, 30 parts by weight of furnace slag, and 20 parts by weight of composite gypsum. The composite gypsum includes 12 parts by weight of power plant gypsum and 8 parts by weight of titanium gypsum.

6. A method for solidifying dredged sand, characterized in that, Includes the following steps: A. Gradation Fitting: The curing agent, water and aggregate are mixed to obtain an inorganic binder. The inorganic binder consists of 10 parts by weight of curing agent, 6 to 10 parts of water, 35 to 41 parts of crushed stone with a particle size range of 16 mm to 31.5 mm, 10 to 15 parts of crushed stone with a particle size range of 5 to 16 mm, 20 to 30 parts of dredged sand with a fineness modulus range of 0.5 to 0.7, and 20 to 25 parts of stone chips. B. Mixing: The sample is obtained by uniform mechanical mixing under the conditions of a temperature range of 15℃~25℃ and a relative humidity range of 50%~60%. C. Compaction and demolding: Place the sample on the press and press it into the mold at a rate of 1 mm / min. The pressure peak during the pressing process shall not exceed 400kN. After the sample is fully pressed into the mold, hold the pressure and let it stand before demolding to obtain the specimen and prepare it for curing. D. Curing: The specimens were cured for more than 4 days, and were immersed in water for curing on the last day.

7. The dredged sand solidification treatment method according to claim 6, characterized in that: The dimensionless fineness modulus of the dredged sand is in the range of 0.5-0.

7.

8. The dredged sand solidification treatment method according to claim 6, characterized in that: The stone chips are crushed stone with a particle size range of 0-5mm.

9. The dredged sand solidification treatment method according to claim 6, characterized in that: The curing agent is a solid waste-based curing agent, which includes 50 parts by weight of steel slag, 30 parts by weight of furnace slag, and 20 parts by weight of composite gypsum. The composite gypsum includes 12 parts by weight of power plant gypsum and 8 parts by weight of titanium gypsum.

10. The dredged sand solidification treatment method according to claim 6, characterized in that: The specimens were first cured in a standard curing chamber at a temperature of 19℃ to 21℃ and a relative humidity of ≥95%. The last day was spent on immersion curing, in which the specimens were sealed and immersed in water at a temperature of 18℃ to 22℃ for 24 hours.

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