Synchronous grouting material based on muddy silt shield slag and preparation method thereof

Abstract

The present invention relates to a synchronous grouting material based on muddy silt shield slag and a preparation method thereof. The raw materials of the synchronous grouting material include, by weight, 13-16 parts of cement, 16-20 parts of slag, 142-147 parts of muddy silt fine sand, 0.03-0.1 parts of ethyl trimethylsilyl acetate, 0.07-0.17 parts of disodium etidronate, 0.03-0.1 parts of pentasodium aminotrimethylenephosphonate, and 63-67 parts of water. The synchronous grouting material uses the muddy silt fine sand as the main raw material to replace the bentonite and fine sand in the synchronous grouting in the prior art, combines with a specific cement additive, and effectively improves the compressive strength and anti-permeability performance of the synchronous grouting material through the synergistic effect of the various components. At the same time, the materials can be locally sourced, and the transportation and disposal costs of a large amount of slag are greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel grouting materials, and more particularly to a synchronous grouting material based on muddy silt shield slag and a preparation method thereof. Background Art

[0002] Synchronous grouting technology is an indispensable and key auxiliary method in shield tunneling. Synchronous grouting during shield tunneling is an effective means to fill the construction gap between the segment lining and the stratum and reduce the subsequent soil deformation. It can enhance the stability of the tunnel and is the key to controlling surface settlement.

[0003] Synchronous grouting slurry is typically a cement mortar, made up of cement, sand, fly ash, bentonite, and water in a specific ratio. Urban subway construction uses an extremely abundant supply of excavated soil from shield tunneling tunnels. Effectively utilizing this resource to create synchronous grouting materials would yield significant economic, environmental, and social benefits.

[0004] There are a series of problems in the synchronous grouting construction process, such as poor slurry fluidity, pipe segment floating, and pipe segment leakage. Quality control is difficult and the construction safety risk is high. First, the floating of the pipe segment is mainly due to the long coagulation time of the slurry. The slurry is in a fluid state for a long time, which makes the buoyancy of the pipe segment greater than its own gravity, resulting in the floating of the pipe segment. Secondly, the leakage of the pipe segment is largely due to the poor anti-seepage ability of the slurry, and groundwater seeps into the tunnel from the gap behind the wall. At the same time, the slurry must have good fluidity during grouting. Because of good fluidity, the slurry pressure loss is small, and it can diffuse farther from the grouting point, making the slurry filling more full.

[0005] To address these issues, scholars both domestically and internationally have conducted extensive research. Traditionally, improving slurry flowability involves adding dispersants or water reducers. While this improves fluidity, it also reduces slurry strength. Furthermore, water reducers are very expensive, making them uneconomical. Traditionally, reducing slurry setting time involves adding accelerators, but this also reduces fluidity, making grouting extremely difficult.

[0006] Therefore, it is of great significance to develop a synchronous grouting material with strong flowability, good filling performance, strong anti-permeability, controllable setting time and strength, and economical and environmentally friendly. Summary of the Invention

[0007] Based on the above-mentioned technical problems existing in the prior art, the present invention provides a synchronous grouting material based on muddy siltstone shield slag. The material uses muddy siltstone fine sand as the main raw material, replacing the bentonite and fine sand in the synchronous grouting in the prior art. Combined with cement and specific additives, the material effectively improves the compressive strength and impermeability of the synchronous grouting material through the synergistic effect between the components. At the same time, local materials can be used, which greatly reduces the cost of transporting and disposing of a large amount of slag.

[0008] In order to achieve the above object, the technical solution of the present invention is as follows:

[0009] A synchronous grouting material based on muddy siltstone shield slag, comprising the following components in parts by weight:

[0010] 13-16 parts cement

[0011] 16-20 parts slag

[0012] 142-147 parts of fine sand containing mud

[0013] 0.03-0.1 parts of ethyl trimethylsilyl acetate

[0014] 0.07-0.17 parts of etidronate disodium

[0015] 0.03-0.1 parts of pentasodium aminotrimethylenephosphonate

[0016] 63-67 parts water.

[0017] In some embodiments, the cement is ordinary Portland cement and / or sulphoaluminate cement.

[0018] In some embodiments, the density of the slag is 2.0-3.0 g / cm 3 ;Specific surface area is 350-500m 2 / kg.

[0019] In some embodiments, the particle size of the mud-containing fine sand is less than 2 mm, and the clay content is 20-30%.

[0020] In some embodiments, the mud-containing fine sand is particles with a particle size of less than 2 mm obtained by multiple screening of shield slag.

[0021] In some embodiments, shield tunneling slag is screened once to separate coarse particles larger than 6 mm and sand-containing mud smaller than 6 mm; the sand-containing mud smaller than 6 mm is then rinsed and screened twice to separate intermediate particles of 2-6 mm and sand-containing mud smaller than 2 mm; the sand-containing mud smaller than 2 mm is separated to obtain mud-containing fine sand and mud, and the mud-containing fine sand is collected.

[0022] The present invention also provides a method for preparing a synchronous grouting material based on muddy siltstone shield slag according to any of the above embodiments, the method comprising the following steps:

[0023] (1) First, cement, slag, mud-containing fine sand and part of water are mixed and stirred thoroughly to obtain a first slurry;

[0024] (2) then mixing ethyl trimethylsilyl acetate with a portion of water and adding the mixture to the first slurry obtained in step (1) above and stirring the mixture thoroughly to obtain a second slurry;

[0025] (3) mixing etidronate disodium with a portion of water and adding the mixture to the second slurry obtained in step (2) above, stirring the mixture thoroughly to obtain a third slurry;

[0026] (4) Finally, pentasodium aminotrimethylenephosphonate and the remaining water are mixed and added to the third slurry obtained in the above step (3) and stirred thoroughly to obtain a synchronous grouting material;

[0027] The entire stirring time of steps (1) to (4) is controlled within 5-10 minutes.

[0028] In some embodiments, the entire stirring time is controlled within 6-8 minutes.

[0029] The technical solution of the present invention, the interaction principle between the additive and each component is as follows:

[0030] 1. Action and reaction mechanism of etidronate disodium

[0031] (1) Hydrolysis of etidronate disodium (C2H9Na2O7P2)

[0032]

[0033] (2) Promote the depolymerization of cement paste flocculation structure

[0034] After cement is mixed with water, a double electric layer structure is formed on the surface of the cement particles due to the hydration of the cement particles, forming a solvated water film. The surface of the cement particles carries opposite charges, which causes association between the cement particles and forms a flocculated structure in the cement slurry. 10% to 30% of the mixing water is wrapped in the cement particles and cannot participate in free flow and lubrication, thereby affecting the fluidity of the cement slurry.

[0035] The -OH hydrophilic groups generated by the hydrolysis of etidronate disodium (C2H9Na2O7P2) are nucleophilic and can be directed to the surface of cement particles, imparting a negative charge to the surface. This creates an electrostatic repulsion, promoting the dispersion of cement particles and disintegrating the flocculated structure of the cement particles, releasing some of the encapsulated water and allowing it to flow, thereby effectively increasing the fluidity of the slurry. Furthermore, the hydrophilic groups are highly polar, so the hydrophilic group adsorption film on the cement particle surface can form a stable solvated water film with water molecules. This water film acts as a lubricant, effectively reducing the sliding resistance between cement particles and thus improving the fluidity of the slurry.

[0036] (3) Chelation effect and accelerated hydration

[0037] The reactions during cement hydration are as follows:

[0038] Tricalcium silicate hydration in cement:

[0039] 2(3CaO·SiO 2 ) + 6H 2 O = 3CaO·SiO 2 ·3H 2 O + 3Ca(OH) 2

[0040] Tricalcium silicate hydration in cement:

[0041] 2(2CaO·SiO 2 ) + 4H 2 O = 3CaO·SiO 2 ·3H 2 O + Ca(OH) 2

[0042] Hydration of tricalcium aluminate in cement:

[0043] 3CaO·Al2O3+ 6H2O = 3CaO·Al2O 3· 6H2O

[0044] 3CaO·Al2O3·6H2O + 3(Ca2SO4·2H2O) + 19H2O=3CaO·Al2O3·3Ca2SO4·31H2O

[0045] Hydration of Tetracalcium Aluminoferrite in Cement:

[0046] 4CaO·Al2O3·Fe2O3+ 7H2O = 3CaO·Al2O3·6H2O + CaO·Fe2O3·H2O

[0047] The hydration product Ca(OH)2 produced by cement hydration ionizes a large amount of Ca in water. 2+ The hydroxyl groups generated by the hydrolysis of etidronate disodium react with the Ca2+ generated by cement hydration. 2+ The formation of a six-ring chelate further accelerates the hydrolysis of Ca(OH)2, promotes the rapid hydration of cement, and exhibits an ideal early strengthening effect. The reaction principle is as follows:

[0048] .

[0049] 2. Mechanism of action of sodium aminotrimethylenephosphonate

[0050] (1) Hydrolysis of sodium aminotrimethylenephosphonate

[0051]

[0052] Na produced by hydrolysis of sodium aminotrimethylenephosphonate + OH generated by cement hydration — Combined with the solids, it generates strongly alkaline NaOH, which reacts with SiO2 in the mud-containing fine sand to form hydrated sodium silicate gel. Its size is smaller than the hydrated calcium silicate produced by cement hydration, which can effectively fill the pores of the hardened paste and improve the strength. The reaction is as follows:

[0053] Na + + OH — = NaOH;

[0054] 2NaOH + SiO2 = Na2SiO3 + H2O;

[0055] (2) H2PO3 — Reacts with Al2O3 in muddy fine sand

[0056] The mineral components of muddy fine sand mainly include quartz, calcite, dolomite, hydrocalcium zeolite, etc. In a strong alkaline environment, Al2O3 in muddy fine sand hydrolyzes to produce Al(OH)3; pentasodium aminotrimethylenephosphonate hydrolyzes to produce H2PO3 — It undergoes polymerization reaction with Al(OH)3 to form air-hardening binders aluminum dihydrogen phosphate and aluminum monohydrogen phosphate, which undergo a violent neutralization reaction with the alkaline substance Ca(OH)2 produced by cement hydration, increasing the solidification speed of the cement paste and forming a dense hardened structure, promoting the coagulation and hardening of the paste; the reaction is as follows:

[0057] Al2O3+ 3H2O = 2Al(OH)3;

[0058] Al(OH)3+ 3H3PO4= Al(H2PO4) + 3H2O;

[0059] 2Al(OH)3+ 3H3PO4= Al2(HPO4)3+ 6H2O;

[0060] Al(OH)3+ H3PO4= AlPO4+ 3H2O;

[0061] (3) Complexation reaction

[0062]

[0063] Under alkaline conditions, complexation reaction occurs, and the inorganic ligands in the cement paste have OH - It is easy to combine with phosphate ions and will preferentially combine with hard acid Ca as the central ion 2+Combined to form a hydroxy complex ion. The phosphonic acid group produced by the hydrolysis of sodium aminotrimethylenephosphonate and the carboxyl group produced by the hydrolysis of disodium etidronate are mostly active group substances containing lone pair electrons. They are typical electron donors and can react with alkali metal ions Ca 2+ Form a stable complex.

[0064] 3. Mechanism of action of ethyl trimethylsilyl acetate

[0065] (1) Hydrolysis of ethyl trimethylsilyl acetate

[0066]

[0067] (2) Hydrolysis of sodium aminotrimethylene phosphate

[0068]

[0069] (3) The amino group and methylene chain generated by the hydrolysis of sodium aminotrimethylene phosphate react with the ethyl silicate group generated by the hydrolysis of ethyl trimethylsilyl acetate to generate ethyl orthosilicate groups. The reaction is as follows:

[0070]

[0071] The ethyl ester groups undergo polymerization to form polyethyl silicate, and the reaction is as follows:

[0072]

[0073] The ethyl silicate groups form a network structure, filling the pores of the hardened cement paste and improving the paste strength and impermeability.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] The technical solution of the present application uses mud-containing fine sand as the main raw material, cement and slag as auxiliary materials, and trimethylsilyl acetate, disodium hydroxyethyl phosphonate and pentasodium aminotrimethylene phosphate as additives. The content of clay mineral components in the mud-containing fine sand is relatively high, and it has good water absorption and expansion properties, and the clay particle size is relatively fine, and the specific surface area of ​​the soil particles per unit mass is large, so it has strong adsorption capacity and ion exchange capacity, which can effectively improve the viscosity and slurry stability of the synchronous grouting material; at the same time, the fine sand particles play a skeleton role in the synchronous grouting material, increasing the strength of the slurry consolidation body; by adding trimethylsilyl acetate to react with each component, the anti-permeability and strength of the synchronous grouting material can be effectively improved; the addition of disodium hydroxyethyl phosphonate effectively improves the flowability and early strength of the synchronous grouting material; the addition of pentasodium aminotrimethylene phosphate effectively improves the compressive strength of the synchronous grouting material and shortens the setting time of the slurry.

[0076] The technical solution of the present invention also has the following advantages:

[0077] (1) The present invention realizes the utilization of large amounts of muddy siltstone shield slag, with the slag component content reaching up to 60%. Compared with traditional synchronous grouting materials, it can achieve zero addition of fly ash, bentonite, and fine sand. At the same time, it can reduce cement usage by 50%, reduce material costs by about 71%, and reduce a large amount of slag transportation and disposal costs, thereby increasing the added value of slag utilization and achieving significant overall economic benefits.

[0078] (2) The compounded admixture can greatly improve the anti-seepage ability of the slurry, reduce the setting time of the slurry, and increase the compressive strength of the slurry; at the same time, it can improve the flowability of the slurry. During the storage and transportation process, the slurry can maintain a certain workability, uniformity and good construction performance. After the slurry is injected into the shield tail through the pipeline, it can fill the gap between the pipe segment and the surrounding rock more fully;

[0079] (3) The shield slag slurrying process adopted by the present invention is simple, has high production efficiency, and occupies a small area of ​​equipment, and can be adapted to small urban subway construction sites.

[0080] (4) The present invention is a green and environmentally friendly synchronous grouting material that can turn slag into treasure, reduce environmental pollution caused by slag transportation and discharge, reduce natural sand and gravel mining, and reduce secondary pollution and carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 Detection diagrams of the fluidity of the synchronous grouting materials of Example 3 and Comparative Example 2; wherein, Figure A is the detection diagram of Example 3, and Figure B is the detection diagram of Comparative Example 2;

[0082] Figure 2 28d compressive strength test diagrams of the synchronous grouting materials of Example 3 and Comparative Example 1; wherein, Figure A is the test diagram of Example 3, and Figure B is the test diagram of Comparative Example 2;

[0083] Figure 3 28d compressive strength test diagrams of the synchronous grouting materials of Example 3 and Comparative Example 2; wherein, Figure A is the test diagram of Example 3, and Figure B is the test diagram of Comparative Example 2;

[0084] Figure 4 28d compressive strength test diagrams of the synchronous grouting materials of Example 3 and Comparative Example 4; wherein, Figure A is the test diagram of Example 3, and Figure B is the test diagram of Comparative Example 4;

[0085] Figure 5 These are the setting time measurement diagrams of the synchronous grouting materials of Examples 1, 2 and Comparative Example 3; wherein, Figure A is the detection diagram of Example 1, Figure B is the detection diagram of Example 2, and Figure C is the detection diagram of Comparative Example 3. DETAILED DESCRIPTION

[0086] The following description sets forth numerous specific details to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific implementations disclosed below.

[0087] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0088] Some of the raw materials used in the following examples and comparative examples of the present invention are as follows:

[0089] Cement: ordinary Portland cement;

[0090] Slag: density is 2.89g / cm 3 , with a specific surface area of ​​422.3m 2 / kg;

[0091] Ethyl trimethylsilyl acetate (C7H 16 O2Si, CAS No.: 4071-88-9), density 0.876 g / mL, specific gravity 0.876;

[0092] Etidronate disodium (C2H9NaO7P2, CAS number: 7414-82-7);

[0093] Pentasodium aminotrimethylene phosphate (C3H7NNa5O9P3, CAS No.: 2235-43-0);

[0094] The muddy fine sand is obtained by using shield slag as raw material and undergoing multiple screenings, as follows:

[0095] (1) The shield tunneling muck is transported into the muck pool by dump trucks, loaded by excavators and other means, and enters the primary screening system through the silo;

[0096] (2) The coarse particles larger than 6 mm and the sand-containing mud smaller than 6 mm are separated by screening using a double-layer shaftless roller screen. The screened coarse particles are transported to the coarse particle storage area via a conveyor belt;

[0097] (3) The sand-containing mud with a size of less than 6 mm obtained in step (2) is washed and then enters the secondary screening system, where a vibrating screening machine is used to separate the intermediate particles of 2-6 mm and the sand-containing mud with a size of less than 2 mm. The intermediate particles are transported to the designated stacking area;

[0098] (4) The sand-containing mud with a particle size of less than 2 mm obtained in step (3) is separated into fine sand and mud containing mud by a cyclone, and the fine sand containing mud is collected; the mud is separated into mud cake and clear water by a filter press;

[0099] The mud-containing fine sand obtained after screening has a clay content of 20-30wt%. Example 1

[0100] A synchronous grouting material based on muddy silt shield slag, comprising the following components in parts by weight:

[0101] 16 parts cement

[0102] 16 parts slag

[0103] 147 parts of mud-containing fine sand

[0104] 67 parts water

[0105] 0.03 parts of ethyl trimethylsilyl acetate

[0106] 0.07 parts of etidronate disodium

[0107] 0.03 parts of pentasodium aminotrimethylene phosphate;

[0108] The preparation method comprises the following steps:

[0109] S1. First, mix cement, slag, mud-containing fine sand and water (40 parts) and stir thoroughly for 2 minutes;

[0110] S2. Then, ethyl trimethylsilyl acetate and water (7 parts) were mixed and added to the above mixture and stirred thoroughly for 1 minute;

[0111] S3. Mix etidronate disodium with water (12 parts) and add to the above mixture, stirring thoroughly for 2 minutes;

[0112] S4. Finally, mix pentasodium aminotrimethylenephosphonate and water (8 parts) and add them to the above mixture and stir thoroughly for 2 minutes to obtain synchronous grouting material. The entire stirring time should be controlled within 6 to 8 minutes. Example 2

[0113] The composition and proportion of each raw material in this example are shown in Table 1, and the preparation method is the same as that in Example 1. Example 3

[0114] The composition and proportion of each raw material in this example are shown in Table 1, and the preparation method is the same as that in Example 1.

[0115] Table 1 Composition and proportion of raw materials of Examples 1-3 (unit: part)

[0116] Comparative Example 1

[0117] The raw material composition and proportion of this comparative example are shown in Table 2, and its preparation method is as follows:

[0118] Use an excavator or forklift to transport the mud-containing fine sand to a twin-shaft forced mixer, add water and stir for 1 minute, transport cement and slag to the mixer through storage tanks and fully mix with the mud-containing fine sand (both equipped with automatic weighing systems) for 2 minutes, then add the early strength agent and polycarboxylic acid high-efficiency water reducer, and continue stirring. The entire mixing process should be controlled within 6-8 minutes. Comparative Example 2

[0119] The raw material composition and proportion of this comparative example are shown in Table 2, and the preparation method is the same as that of comparative example 1. Comparative Example 3

[0120] The raw material composition and proportion of this comparative example are shown in Table 2, and the preparation method is the same as that of comparative example 1. Comparative Example 4

[0121] The raw material composition and proportion of this comparative example are shown in Table 2, and the preparation method is the same as that of comparative example 1.

[0122] Table 2 Raw material composition and proportion of comparative examples 1-4 (unit: part)

[0123]

[0124] The synchronous grouting materials obtained in Examples 1-3 and Comparative Examples 1-4 were subjected to relevant performance tests, as follows:

[0125] The setting time test method refers to the relevant provisions of the current industry standard "Standard for Test Methods of Basic Properties of Building Mortar" (JGJ / T70-2009);

[0126] The fluidity test method refers to the provisions of the truncated cone fluidity test in the current national standard "Technical Specifications for Application of Cement-based Grouting Materials" (GB / T50448-2015);

[0127] The compressive strength test method refers to the provisions of the unconfined compressive strength test in the current industry standard "Cement-Soil Mix Design Code" (JGJ / T 233-2011);

[0128] The test methods for anti-seepage pressure and anti-seepage grade refer to the relevant provisions of "Standard for Test Methods for Basic Properties of Building Mortar" (JGJ / T70-2009) and "Ready-mixed Mortar" (GB / T 25181-2019).

[0129] The relevant test results are shown in Table 3 and Figure 1-Figure 5 shown.

[0130] Table 3 Test results of grouting material properties of Examples 1-3 and Comparative Examples 1-4

[0131]

[0132] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0133] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A synchronous grouting material based on muddy silt shield slag, characterized in that: Calculated by weight, it includes the following components: 13-16 parts cement 16-20 parts slag 142-147 parts of fine sand containing mud 0.03-0.1 parts of ethyl trimethylsilyl acetate 0.07-0.17 parts of etidronate disodium 0.03-0.1 parts of pentasodium aminotrimethylenephosphonate 63-67 parts water; The particle size of the mud-containing fine sand is less than 2 mm, and the clay content is 20-30%.

2. The synchronous grouting material based on muddy silt shield slag according to claim 1 is characterized in that: The cement is ordinary Portland cement and / or sulphoaluminate cement.

3. The synchronous grouting material based on muddy silt shield slag according to claim 1 is characterized in that: The density of the slag is 2.0-3.0 g / cm 3 ;Specific surface area is 350-500m 2 / kg.

4. The synchronous grouting material based on muddy silt shield slag according to claim 1, characterized in that: The mud-containing fine sand is particles with a particle size of less than 2 mm obtained by multiple screening of shield slag.

5. The synchronous grouting material based on muddy silt shield slag according to claim 4 is characterized in that: The screening of the mud-containing fine sand comprises the following steps: The shield slag is screened once to separate coarse particles larger than 6mm and sandy mud smaller than 6mm; the sandy mud smaller than 6mm is then washed and screened twice to separate intermediate particles of 2-6mm and sandy mud smaller than 2mm; the sandy mud smaller than 2mm is separated to obtain mud-containing fine sand and mud, and the mud-containing fine sand is collected.

6. The method for preparing synchronous grouting material based on muddy silt shield slag according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) First, cement, slag, mud-containing fine sand and part of water are mixed and stirred thoroughly to obtain a first slurry; (2) then mixing ethyl trimethylsilyl acetate with a portion of water and adding the mixture to the first slurry obtained in step (1) and stirring the mixture thoroughly to obtain a second slurry; (3) mixing etidronate disodium with a portion of water and adding the mixture to the second slurry obtained in step (2) above, stirring the mixture thoroughly to obtain a third slurry; (4) Finally, pentasodium aminotrimethylenephosphonate and the remaining water are mixed and added to the third slurry obtained in the above step (3) and stirred thoroughly to obtain a synchronous grouting material; The entire stirring time of steps (1) to (4) is controlled within 5-10 minutes.

7. The method for preparing synchronous grouting material based on muddy silt shield slag according to claim 6, characterized in that: The entire stirring time is controlled within 6-8 minutes.

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