A preparation method for high-volume shield silt sand concrete

Abstract

The present invention relates to a method for preparing high-volume shield silt concrete, comprising the following steps: preparing raw materials for the concrete, comprising 203-233 kg / m³ of cement, 156-166 kg / m³ of admixture, 1730-1766 kg / m³ of aggregate, 165-180 kg / m³ of water, and 5.5-6.3 kg / m³ of admixture, wherein the aggregate has a sand fraction of 42-45%, and the shield silt in the aggregate replaces manufactured sand by 14-17%; and mixing to obtain C35 concrete. By replacing some manufactured sand with shield silt, the present invention overcomes the limitations of traditional C35 concrete preparation methods in the use of high-volume silt, thereby improving the mechanical properties and workability of the concrete while achieving efficient utilization of silt resources.

Description

Technical Field

[0001] The invention relates to the technical field of C35 concrete production, and in particular to a preparation method of high-content shield silt concrete. Background Art

[0002] The shield tunneling method is a fully mechanized construction method within the underground tunneling method. It involves propelling a shield machine underground, using the shield casing and segments to support the surrounding rock and prevent collapse into the tunnel. Simultaneously, a cutting device excavates soil in front of the excavation face, which is then transported out of the tunnel by excavation machinery. Jacks then pressurize and jack the tunnel from behind, and precast concrete segments are assembled to form the tunnel structure. Shield tunneling in silty sand formations produces a large amount of silty sand. Effective utilization can not only reduce environmental pollution but also lower project costs. Currently, C35 concrete typically uses manufactured sand as fine aggregate, priced at approximately 120 yuan per ton. Due to the lack of fine particles in manufactured sand, the concrete's fluidity is impaired. Replacing some of this manufactured sand with shield silt sand, priced at approximately 25 yuan per ton, can significantly reduce production costs. However, it is difficult to directly use high-content silt sand in traditional concrete preparation methods because the addition of silt sand will significantly affect the mechanical properties and durability of concrete. Therefore, it is of great practical significance to develop a concrete preparation method that can effectively utilize shield silt sand.

[0003] Chinese patent publication number CN118344045A discloses a functional additive for recycling silt-sand layer slurry shield slag in concrete, a preparation method, and its application. The preparation method comprises the following steps: preparing a polyquaternary ammonium salt cationic polymer, a small molecule phosphate anionic polymer, a sodium polyacrylate viscosity regulator, and an adaptive small material in a mass ratio of 1:1.0-2.0:5.0-10.0:1-2.5, and uniformly mixing them at room temperature; the concrete mix ratio parameter characteristics are as follows: The amount of shield slag in the silt layer accounts for ≤35% of the total sand usage; the 45μm sieve residue of the shield slag in the silt layer is <20%, the 75μm sieve residue is 35~40%, and the mud content is ≤15%; and the amount of the above-mentioned functional additives ranges from 0.6 to 2.0%; among them, the "isolation + blocking" synergistic mud-blocking effect of the components "polyquaternary ammonium salt cationic polymer + small molecule phosphate anionic polymer" and the viscosity-reducing effect of the component sodium polyacrylate viscosity regulator effectively reduce the negative impact of shield slag on the performance of polycarboxylic acid water-reducing agent.

[0004] The above-mentioned existing technical solutions have the following defects: the above-mentioned method uses polyquaternary ammonium salt cationic polymers and small molecule phosphate anionic polymers to prepare a functional additive with mud-blocking effect, which effectively reduces the adverse effects of these mud components on the performance of polycarboxylate water-reducing agent by reducing the mud content of shield silt; however, the preparation process of these polymers is quite complicated and requires multiple steps, and each step requires precise control and operation. This complexity will undoubtedly increase the difficulty of operation in the actual production process; in addition, although the above-mentioned functional additives can improve the durability of concrete to a certain extent, their negative impact on the mechanical properties (such as compression, tension, shear, bending, flexural and bond strength) and workability (such as slump, fluidity, cohesion, and water retention) of concrete has not been fully optimized and improved. In particular, when a high proportion of silt is added to concrete, its performance improvement effect may not be ideal, and further research and improvement are still needed to ensure that optimal performance can be achieved under various construction conditions. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a method for preparing high-content shield silt sand concrete in response to the above-mentioned deficiencies in the prior art. By using shield silt sand to replace part of the machine-made sand, the method solves the limitations of the traditional C35 concrete preparation method in the use of high-content silt sand, and has the advantages of improving the mechanical properties and workability of concrete while achieving efficient utilization of silt sand resources.

[0006] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0007] A method for preparing high-volume shield silt concrete comprises the following steps:

[0008] S1. Preparing raw materials for the concrete, the raw materials for the concrete including 203-233 kg / m³ cement, 156-166 kg / m³ admixture, 1730-1766 kg / m³ aggregate, 165-180 kg / m³ water, and 5.5-6.3 kg / m³ admixture, wherein the sand content of the aggregate is 42-45%, and the replacement rate of shield silt in the aggregate for machined sand is 14-17%;

[0009] S2 first adds gravel in the aggregate and stirs for 1-2 minutes, then adds sand in the aggregate and stirs for 1-2 minutes, then adds cement and admixtures into the mixer and stirs for 1-2 minutes, finally adds the remaining raw materials of the concrete by the same mixing method, wet mixes for 2-3 minutes, until the mixture is evenly dispersed, and obtains C35 concrete.

[0010] Furthermore, in S1, the aggregate includes 639-647 kg / m³ of machine-made sand, 114-120 kg / m³ of shield silt sand, 755-775 kg / m³ of 10-25 mm crushed stone, and 194-252 kg / m³ of 5-10 mm crushed stone.

[0011] Furthermore, in S1, the admixture includes 78-88 kg / m³ fly ash and 75-80 kg / m³ slag powder.

[0012] Furthermore, in said S1, the raw materials of concrete include 203, 205, 208, 215, 220, 225, 230 or 233 kg / m³ cement, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87 or 88 kg / m³ fly ash, 75, 76, 77, 78, 79 or 80 kg / m³ slag powder, 639, 640, 641, 642, 643, 644, 645, 646 or 647 kg / m³ machine-made sand, 114, 115, 116, 117, 118, 119 or 1 20kg / m³ shield silt sand, 755, 760, 765, 770 or 775kg / m³ 10-25mm gravel, 194, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250 or 252kg / m³ 5-10mm gravel, 165, 168, 170, 172, 175, 178 or 180kg / m³ water, and 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2 or 6.3kg / m³ admixture.

[0013] Furthermore, in S1, the mass ratio of cement, fly ash and slag powder is controlled to be 1:0.33~0.44:0.33~0.39, the mass ratio of the mixture of cement and admixture, and water is 1:0.44~0.47, and the mass ratio of 10~25mm gravel and 5~10mm gravel is approximately 1:3~4.

[0014] Furthermore, in S1, the raw materials of the concrete include 203 kg / m³ cement, 88 kg / m³ fly ash, 78 kg / m³ slag powder, 639 kg / m³ machine-made sand, 120 kg / m³ shield silt sand, 755 kg / m³ 10-25 mm crushed stone, 252 kg / m³ 5-10 mm crushed stone, 165 kg / m³ water, and 5.5 kg / m³ admixture.

[0015] Alternatively, in S1, the raw materials of the concrete include 233 kg / m³ cement, 78 kg / m³ fly ash, 78 kg / m³ slag powder, 647 kg / m³ machine-made sand, 114 kg / m³ shield silt sand, 775 kg / m³ 10-25 mm crushed stone, 194 kg / m³ 5-10 mm crushed stone, 180 kg / m³ water, and 6.3 kg / m³ admixture.

[0016] Furthermore, in S1, silty sand with a mud content of ≤30% and a water content of ≤18% is pre-soaked in a modifier until it is saturated with water, and stirring is continued and an auxiliary agent is added dropwise during the soaking period. After the soaking is completed, the sand is filtered and dried, and then mixed with the abrasive, ball milled and sieved to obtain the shield silt sand; wherein the modifier is composed of the following raw materials in parts by weight: 10-15 parts of bis-PEG-18 methyl ether dimethyl silane, 5-8 parts of aluminum lactate, 4-6 parts of attapulgite, 5-10 parts of triethoxyoctylsilane, and water is added to 100 parts.

[0017] Furthermore, during the soaking process, the modifier is composed of the following raw materials in parts by weight: 5, 6, 7, 8, 9 or 10 parts of triethoxycaprylylsilane, 10, 11, 12, 13, 14 or 15 parts of bis-PEG-18 methyl ether dimethyl silane, 5, 6, 7 or 8 parts of aluminum lactate, 4, 5 or 6 parts of attapulgite, and water is added to 100 parts.

[0018] Furthermore, during the soaking process, the auxiliary agent is composed of the following raw materials in parts by weight: 20 to 30 parts of sodium carboxymethyl cellulose, 30 to 40 parts of hydroxyethyl urea, and water added to 100 parts.

[0019] Furthermore, during the soaking process, the auxiliary agent is composed of the following raw materials in parts by weight: 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 parts of sodium carboxymethyl cellulose and 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40 parts of hydroxyethyl urea, and water is added to 100 parts.

[0020] Furthermore, during the soaking process, the volume ratio of the silty sand, the modifier and the additive is controlled to be 1:5-15:0.5-1.5.

[0021] Furthermore, during the soaking process, the volume ratio of silt sand, modifier and additive is controlled to be 1:5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15:0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5.

[0022] Furthermore, during the soaking process, the height difference between the auxiliary agent addition port and the liquid level of the modifier is controlled to be 0.3 m.

[0023] Furthermore, during the soaking process, the soaking time is controlled to be 4-6 hours and the stirring speed is controlled to be 1000-1250 r / min.

[0024] Furthermore, during the ball milling process, the abrasive is composed of the following raw materials in parts by weight: 38-45 parts of hydrated silica, 30-35 parts of talc, and 20-32 parts of microcrystalline cellulose.

[0025] Furthermore, during the ball milling process, the abrasive is composed of the following raw materials in parts by weight: 38, 39, 40, 41, 42, 43, 44 or 45 parts of hydrated silica, 30, 31, 32, 33, 34 or 35 parts of talc, and 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 or 32 parts of microcrystalline cellulose.

[0026] Furthermore, during the ball milling process, ceramic balls are used as ball milling media, and water is added for wet milling, and the mass ratio of the silty sand, abrasive, ball milling media and water obtained by soaking is controlled to be 1:0.08~0.12:0.5~1.5:0.5~1.0.

[0027] Furthermore, in the ball milling process, ceramic balls are used as ball milling media, and water is added for wet milling, and the mass ratio of the silt sand, abrasive, ball milling media and water obtained by soaking is controlled to be 1:0.08, 0.09, 0.10, 0.11 or 0.12:0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.3, 1.4 or 1.5:0.5, 0.6, 0.7, 0.8, 0.9 or 1.0.

[0028] Furthermore, during the ball milling process, the ball milling speed is controlled to be 10-15 r / min and the ball milling time is 2-3 h.

[0029] In summary, the beneficial technical effects of the present invention are:

[0030] 1. The present invention pre-screens the components of the slurry and aggregate in concrete. The sand ratio of the aggregate and the replacement rate of shield silt for manufactured sand are optimized based on technical parameters such as the apparent density of these components, the average slurry thickness surrounding the aggregate, and the minimum slurry volume. This allows the amount and ratio of each component in the concrete raw material to be determined. The optimal addition of 114-120 kg / m³ of shield silt to the concrete is found. The resulting C35 concrete not only meets standard requirements for mechanical and workability properties, but also other properties. It also achieves efficient utilization of silt resources.

[0031] 2. The present invention sequentially performs soaking and ball milling modification treatments on silty sand. During the soaking process, bis-PEG-18 methyl ether dimethyl silane is used as a water-soluble silicone wax, which fills the cracks and sharp surfaces of the silty sand through aluminum lactate and attapulgite, thereby improving the surface morphology of the silty sand. Triethoxyoctylsilane is then added to significantly improve the surface smoothness of the silty sand and the bonding strength between the machine-made sand particles, reducing the negative impact on the slurry and admixtures, thereby improving working performance. During the ball milling process, hydrated silica, talc, and microcrystalline cellulose are then used for ball milling dispersion, further optimizing the gradation of fine particles in the silty sand and improving their cross-sectional adhesion with the slurry, thereby contributing to improved mechanical properties of concrete.

[0032] 3. The shield silt used in this invention is industrial waste generated during shield construction, which has the dual advantages of environmental protection and resource recycling. By using shield silt as a component of concrete, it not only reduces waste accumulation and environmental pollution, but also reduces the production cost of concrete, achieving a win-win situation in economic and environmental benefits.

[0033] 4. The preparation method of the present invention has simple steps, does not require complex equipment and other raw materials, and ensures the uniformity and stability of the concrete. During the mixing process, the addition of admixtures further improves the fluidity, cohesion and water retention of the concrete, so that the concrete has better working performance during the construction process. DETAILED DESCRIPTION

[0034] In order to make the technical means, creative features, objectives and functions achieved by the present invention clearer and easier to understand, the present invention is further elaborated below in conjunction with specific implementation methods.

[0035] Example 1: A method for preparing high-volume shield silt sand concrete disclosed in the present invention comprises the following steps:

[0036] S1 prepares the raw materials for concrete, which include 233kg / m³ cement, 78kg / m³ fly ash, 78kg / m³ mineral powder, 647kg / m³ machine-made sand, 114kg / m³ shield silt sand, 775kg / m³ 10~25mm crushed stone, 194kg / m³ 5~10mm crushed stone, 180kg / m³ water, and 6.3kg / m³ polycarboxylic acid admixture; among which,

[0037] The cement is P.II52.5 Portland cement, produced by the Ningguo Cement Plant of Anhui Conch Cement Co., Ltd.

[0038] The fly ash is Class F Grade I fly ash, produced in Haining;

[0039] The slag powder is S95 grade slag powder, produced by Ningbo Henglong New Materials Co., Ltd., with a density ≥2.8g / cm³, a specific surface area ≥400㎡ / kg, a fluidity ratio ≥95%, a loss on ignition ≤1.0%, a 7-day activity index ≥70%, and a 28-day activity index ≥95%.

[0040] The machine-made sand is Class II medium sand in Zone 2, produced in Shaoxing;

[0041] Shield silt sand is silty sand that has been processed after shield construction through silty sand strata. It is produced in Shaoxing. GBJ145-90 "Soil Classification Standard" stipulates that soil with a fine particle content between 15% and 50% and fine particles in the form of silt is called silty sand.

[0042] The crushed stone is available in two sizes: 5-10mm and 10-25mm. It is produced in Shaoxing and has a mud content of ≤0.5%, 0 mud blocks, ≤5% needle-like flakes, a crushing value of ≤10%, an apparent density of ≥2600kg / m³, a porosity of ≤43%, and a water absorption rate of ≤1.0%.

[0043] The admixture is a polycarboxylic acid high-performance water-reducing agent produced in Lanxi, with a pH value of 4.0-4.7, a density of 1.02-1.06 g / cm³, a cement paste fluidity ≥180 mm, a water reduction rate ≥25%, an air content ≤6.0%, a 1-hour slump loss ≤80 mm, a 7-day compressive strength ratio ≥150%, and a 28-day compressive strength ratio ≥140%.

[0044] The water is tap water from Shaoxing;

[0045] S2 first adds gravel in the aggregate and stirs for 2 minutes, then adds sand in the aggregate and stirs for 2 minutes, then adds cement and admixtures into the mixer and stirs for 2 minutes, and finally adds the remaining raw materials of concrete by the same mixing method, wet mixes for 2 minutes, until the mixture is evenly dispersed, and obtains C35 concrete.

[0046] Example 2: A method for preparing high-volume shield silt sand concrete disclosed in the present invention, which is different from Example 1 in that it includes the following steps:

[0047] S1 prepares the raw materials for concrete, which include 203kg / m³ cement, 88kg / m³ fly ash, 78kg / m³ slag powder, 639kg / m³ machine-made sand, 120kg / m³ shield silt sand, 755kg / m³ 10-25mm crushed stone, 252kg / m³ 5-10mm crushed stone, 165kg / m³ water, and 5.5kg / m³ admixture;

[0048] S2 first adds gravel in the aggregate and stirs for 2 minutes, then adds sand in the aggregate and stirs for 2 minutes, then adds cement and admixtures into the mixer and stirs for 2 minutes, and finally adds the remaining raw materials of concrete by the same mixing method, wet mixes for 2 minutes, until the mixture is evenly dispersed, and obtains C35 concrete.

[0049] Example 3: A method for preparing high-content shield silt concrete disclosed in the present invention. The difference from Example 1 is that, in S1, the shield silt is pre-treated as follows:

[0050] S11 is configured with modifiers, additives, and abrasives; wherein,

[0051] The modifier is composed of the following raw materials in parts by weight: 10 parts of bis-PEG-18 methyl ether dimethyl silane, 5 parts of aluminum lactate, 4 parts of attapulgite, 5 parts of triethoxycaprylylsilane, and water is added to 100 parts;

[0052] The auxiliary agent is composed of the following raw materials in parts by weight: 20 parts of sodium carboxymethyl cellulose, 30 parts of hydroxyethyl urea, and water added to 100 parts;

[0053] The abrasive is composed of the following raw materials in parts by weight: 38 parts of hydrated silica, 30 parts of talc, and 20 parts of microcrystalline cellulose;

[0054] S12: soaking silty sand with a mud content of ≤30% and a water content of ≤18% in the modifier obtained in S11 until it is saturated with water, stirring continuously during the soaking period and adding the additive obtained in S11 dropwise, controlling the volume ratio of silty sand, modifier and additive to be 1:5:0.5, the height difference between the additive addition port and the liquid level of the modifier to be 0.3 m, and the soaking time to be 5 h;

[0055] S13 mixes the silty sand obtained in S12 and the abrasive obtained in S11, uses ceramic balls as ball milling media, and adds water for wet grinding. The mass ratio of the silty sand, abrasive, ball milling media and water obtained by soaking is controlled to be 1:0.08:0.5:0.5, the ball milling speed is 10 r / min, and the ball milling time is 3 h. After the ball milling screening is completed, shield silt sand is obtained.

[0056] Example 4: A method for preparing high-content shield silt concrete disclosed in the present invention. The difference from Example 1 is that, in S1, the shield silt is pre-treated as follows:

[0057] S11 is configured with modifiers, additives, and abrasives; wherein,

[0058] The modifier is composed of the following raw materials in parts by weight: 12 parts of bis-PEG-18 methyl ether dimethyl silane, 6 parts of aluminum lactate, 2 parts of attapulgite, 8 parts of triethoxycaprylylsilane, and water is added to 100 parts;

[0059] The auxiliary agent is composed of the following raw materials in parts by weight: 24 parts of sodium carboxymethyl cellulose, 36 parts of hydroxyethyl urea, and water added to 100 parts;

[0060] The abrasive is composed of the following raw materials in parts by weight: 42 parts of hydrated silica, 33 parts of talc, and 25 parts of microcrystalline cellulose;

[0061] S12: soaking silty sand with a mud content of ≤30% and a water content of ≤18% in the modifier obtained in S11 until it is saturated with water. During the soaking period, stirring is continued and the additive obtained in S11 is added dropwise. The volume ratio of silty sand, modifier and additive is controlled to be 1:10:1.2. The height difference between the additive addition port and the liquid level of the modifier is 0.3 m. The soaking time is 5 hours.

[0062] S13 mixes the silty sand obtained in S12 and the abrasive obtained in S11, uses ceramic balls as ball milling media, and adds water for wet grinding. The mass ratio of the silty sand, abrasive, ball milling media and water obtained by soaking is controlled to be 1:0.10:1.3:0.8, the ball milling speed is 10 r / min, and the ball milling time is 3 h. After the ball milling screening is completed, shield silt sand is obtained.

[0063] Example 5: A method for preparing high-content shield silt concrete disclosed in the present invention. The difference from Example 1 is that, in S1, the shield silt is pre-treated as follows:

[0064] S11 is configured with modifiers, additives, and abrasives; wherein,

[0065] The modifier is composed of the following raw materials in parts by weight: 15 parts of bis-PEG-18 methyl ether dimethyl silane, 8 parts of aluminum lactate, 6 parts of attapulgite, 10 parts of triethoxycaprylylsilane, and water is added to 100 parts;

[0066] The auxiliary agent is composed of the following raw materials in parts by weight: 30 parts of sodium carboxymethyl cellulose, 40 parts of hydroxyethyl urea, and water added to 100 parts;

[0067] The abrasive is composed of the following raw materials in parts by weight: 45 parts of hydrated silica, 35 parts of talc, and 32 parts of microcrystalline cellulose;

[0068] S12: soaking silty sand with a mud content of ≤30% and a water content of ≤18% in the modifier obtained in S11 until it is saturated with water. During the soaking period, stirring is continued and the additive obtained in S11 is added dropwise. The volume ratio of silty sand, modifier and additive is controlled to be 1:15:1.5. The height difference between the additive addition port and the liquid level of the modifier is 0.3 m. The soaking time is 5 h.

[0069] S13 mixes the silt sand obtained in S12 and the abrasive obtained in S11, uses ceramic balls as ball milling media, and adds water for wet grinding. The mass ratio of the silt sand, abrasive, ball milling media and water obtained by soaking is controlled to be 1:0.12:1.5:1.0, the ball milling speed is 10 r / min, and the ball milling time is 3 h. After the ball milling screening is completed, shield silt sand is obtained.

[0070] Comparative Example 1: A preparation method of high-content shield silt sand concrete disclosed in the present invention. The difference from Example 3 is that the replacement rate of shield silt sand for machine-made sand is 0%.

[0071] Comparative Example 2: A preparation method of high-content shield silt sand concrete disclosed in the present invention. The difference from Example 3 is that the replacement rate of shield silt sand for machine-made sand is 5%.

[0072] Comparative Example 3: A preparation method of high-content shield silt sand concrete disclosed in the present invention. The difference from Example 3 is that the replacement rate of shield silt sand for machine-made sand is 10%.

[0073] Comparative Example 4: A method for preparing high-content shield silt sand concrete disclosed in the present invention, which is different from Example 3 in that no modifier is used.

[0074] Comparative Example 5: A method for preparing high-content shield silt sand concrete disclosed in the present invention, which is different from Example 3 in that no additives are used.

[0075] Comparative Example 6: A method for preparing high-content shield silt sand concrete disclosed in the present invention, which is different from Example 3 in that no abrasive is used.

[0076] Test Example 1: The C35 concrete of Examples 3 to 5 and Comparative Examples 1 to 6 was first added to the test mold in layers and portions, vibrated for 1.5 to 2.5 minutes, and demolded after 12 to 24 hours of vibration molding. The concrete specimens were cured to obtain the specimens. The specimens were intact and had no defects in appearance. The performance of the concrete specimens was then tested according to the slump method and GB / T50081-2019. The test results are shown in Table 1.

[0077] Table 1

[0078] Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Slump / mm 221 230 210 121 151 138 128 180 142 Expansion / mm 580 590 560 455 465 470 460 510 480 Liquidity good good good Difference good good Difference good good Cohesion good good good good good good Difference good Difference Water retention good good good Difference good good good good good Density / kg / m³ 2296.0 / / 2303.4 2301.6 2302.6 / / / 28d compressive strength 41.4±2.1 41.2±1.5 43.5±2.3 22.4±2.0 30.6±3.3 30.9±2.5 32.8±2.8 36.4±2.7 25.6±2.5

[0079] As can be seen from Table 1,

[0080] 1. The present invention pre-screens the components of the slurry and aggregate in concrete. The sand ratio of the aggregate and the replacement rate of shield silt for manufactured sand are optimized based on technical parameters such as the apparent density of these components, the average slurry thickness surrounding the aggregate, and the minimum slurry volume. This allows the amount and ratio of each component in the concrete raw material to be determined. The optimal addition of 114-120 kg / m³ of shield silt to the concrete is found. The resulting C35 concrete not only meets standard requirements for mechanical and workability properties, but also other properties. It also achieves efficient utilization of silt resources.

[0081] 2. The present invention sequentially performs soaking and ball milling modification treatments on silty sand. During the soaking process, bis-PEG-18 methyl ether dimethyl silane is used as a water-soluble silicone wax, which fills the cracks and sharp surfaces of the silty sand through aluminum lactate and attapulgite, thereby improving the surface morphology of the silty sand. Triethoxyoctylsilane is then added to significantly improve the surface smoothness of the silty sand and the bonding strength between the machine-made sand particles, reducing the negative impact on the slurry and admixtures, thereby improving working performance. During the ball milling process, hydrated silica, talc, and microcrystalline cellulose are then used for ball milling dispersion, further optimizing the gradation of fine particles in the silty sand and improving their cross-sectional adhesion with the slurry, thereby contributing to improved mechanical properties of concrete.

[0082] 3. The shield silt used in this invention is industrial waste generated during shield construction, which has the dual advantages of environmental protection and resource recycling. By using shield silt as a component of concrete, it not only reduces waste accumulation and environmental pollution, but also reduces the production cost of concrete, achieving a win-win situation in economic and environmental benefits.

[0083] 4. The preparation method of the present invention has simple steps, does not require complex equipment and other raw materials, and ensures the uniformity and stability of the concrete. During the mixing process, the addition of admixtures further improves the fluidity, cohesion and water retention of the concrete, so that the concrete has better working performance during the construction process.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing high-content shield silt sand concrete, characterized by: The following steps are included: S1. Preparing raw materials for the concrete, the raw materials for the concrete including 203-233 kg / m³ cement, 156-166 kg / m³ admixture, 1730-1766 kg / m³ aggregate, 165-180 kg / m³ water, and 5.5-6.3 kg / m³ admixture, wherein the sand content of the aggregate is 42-45%, and the replacement rate of shield silt in the aggregate for machined sand is 14-17%; S2: First add the crushed stone in the aggregate and stir for 1-2 minutes, then add the sand in the aggregate and stir for 1-2 minutes, then add the cement and admixture into the mixer and stir for 1-2 minutes, finally add the remaining raw materials of the concrete by the same mixing method, wet mix for 2-3 minutes, until the mixture is evenly dispersed, to obtain C35 concrete; In S1, silty sand with a mud content of ≤30% and a water content of ≤18% is pre-soaked in a modifier until it is saturated with water, and stirring is continued during the soaking period and an auxiliary agent is added dropwise. After the soaking is completed, the sand is filtered and dried, and then mixed with abrasive, ball milled and sieved to obtain the shield silt sand; wherein the modifier is composed of the following raw materials in parts by weight: 10-15 parts of bis-PEG-18 methyl ether dimethyl silane, 5-8 parts of aluminum lactate, 4-6 parts of attapulgite, 5-10 parts of triethoxyoctylsilane, and water is added to 100 parts; During the soaking process, the auxiliary agent is composed of the following raw materials in parts by weight: 20-30 parts of sodium carboxymethyl cellulose, 30-40 parts of hydroxyethyl urea, and water added to 100 parts; During the soaking process, the volume ratio of silty sand, modifier and additive is controlled to be 1: (5-15): (0.5-1.5); During the ball milling process, the abrasive is composed of the following raw materials in parts by weight: 38-45 parts of hydrated silica, 30-35 parts of talc, and 20-32 parts of microcrystalline cellulose.

2. The method for preparing high-content shield silt sand concrete according to claim 1, characterized in that: In the S1, the aggregate includes 639-647 kg / m³ of machine-made sand, 114-120 kg / m³ of shield silt sand, 755-775 kg / m³ of 10-25 mm crushed stone, and 194-252 kg / m³ of 5-10 mm crushed stone.

3. The method for preparing high-content shield silt sand concrete according to claim 1, wherein: In the S1, the admixture includes 78-88 kg / m³ fly ash and 75-80 kg / m³ slag powder.

4. The method for preparing high-content shield silt sand concrete according to claim 1, wherein: During the soaking process, the soaking time is controlled to be 4-6 hours and the stirring speed is controlled to be 1000-1250 r / min.

5. The method for preparing high-content shield silt sand concrete according to claim 1, characterized in that: During the ball milling process, ceramic balls are used as ball milling media, and water is added for wet milling. The mass ratio of the silty sand, abrasive, ball milling media and water obtained by soaking is controlled to be 1: (0.08-0.12): (0.5-1.5): (0.5-1.0).

6. The method for preparing high-content shield silt sand concrete according to claim 5, characterized in that: During the ball milling process, the ball milling speed is controlled to be 10-15 r / min, and the ball milling time is 2-3 h.