Cement-loaded multi-scale silicon source composite anti-seepage grouting material and preparation method thereof

Abstract

The invention discloses a cement-loaded multi-scale silicon source composite anti-seepage grouting material and a preparation method thereof, and belongs to the field of geotechnical engineering anti-seepage grouting materials. The grouting material is prepared from ordinary Portland cement, micron-scale rice hull ash, nano-scale nano silicon dioxide and sodium bentonite. The rice hull ash reacts with the volcanic ash through physical filling to optimize micron-sized pores; nano-scale pores are filled with nano-silicon dioxide, cement hydration is accelerated, and the nano-silicon dioxide and the nano-silicon dioxide synergistically optimize the pore structure and promote densification of C-S-H gel. The sodium bentonite can retain water, thicken and improve the stability of the slurry. The cross-scale synergistic effect of the multi-scale silicon sources constructs a multi-level compact filling structure from nanometer to micrometer and a multi-level hydration reaction enhancing system in the grouting material, the compactness and anti-seepage performance of the material are remarkably improved, and the grouting material is suitable for engineering fields such as water conservancy dams, tunnels, deep mines, landfills and the like with extremely high anti-seepage performance requirements.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ordinary Portland cement-based building materials, and particularly relates to a cement-loaded multi-scale silicon source composite anti-seepage grouting material and a preparation method. BACKGROUND

[0002] In underground engineering, the fissures of surrounding rock form seepage channels under the action of geological water pressure, which can easily cause geological disasters and erode the structure. Grouting technology has been widely used in engineering and has achieved good results by injecting slurry into the stratum under high pressure to build an anti-seepage curtain.

[0003] Traditional Portland cement-based grouting materials are widely used, but the hardened body contains easily erodible calcium hydroxide crystals and micron-sized capillary pores, resulting in insufficient compactness and weak anti-seepage ability. Using auxiliary cementitious materials for modification has become the mainstream technical path and has achieved certain results, but existing solutions are mostly limited to single-scale action.

[0004] At the micron scale, rice husk ash is widely used due to its high pozzolanic activity, which can consume calcium hydroxide and fill the inter-particle gaps through pozzolanic reaction, and has achieved good results in improving material density. However, due to the limitation of particle size, rice husk ash can only act on micron-sized pores and has limited optimization ability for nanoscale gel pores.

[0005] At the nanoscale, nanosilica can fill nanoscale pores and act as a crystal nucleus site, accelerating the hydration process and forming a dense gel structure. The modification effect has been proven. However, its production cost is high and it is prone to agglomeration in the slurry, which may become a structural defect source, severely restricting its engineering application.

[0006] In recent years, the technology of extracting nanosilica from rice husk ash has realized the cascade utilization of agricultural waste, which can greatly reduce the cost of nanomaterials and meet the national resource utilization demand. However, there is still a lack of systematic research on how to scientifically compound silicon materials of different scales to achieve synergistic effect. Existing research has not thoroughly explained the multi-scale synergistic mechanism, and has not optimized the design for the special requirements of anti-seepage grouting materials such as ultra-low permeability and high slurry stability.

[0007] In summary, the existing technology in the field of anti-seepage grouting materials still has the following defects: 1. The microstructure of traditional cement-based grouting materials has inherent defects. The calcium hydroxide crystals in the hardened body are easily eroded, and the connected capillary pores form seepage channels, resulting in insufficient compactness, weak anti-seepage ability, and difficult to guarantee durability; 2. Single-scale modification technology has limited performance improvement, with clear range limitations: micron-scale modification has no effect on nanoscale gel pores, nanomaterials are prone to agglomeration and have high cost, which severely restricts engineering application; 3. There is a lack of systematic solutions for multi-scale synergistic effects. Existing research has not elucidated the synergistic mechanism in depth, has not optimized the design for the ultra-low permeability and high grout stability requirements of anti-seepage grouting materials, and lacks systematic technical guidance in key aspects such as proportioning design and nanomaterial dispersion process. Summary of the Invention

[0008] The technical problem to be solved by the present invention is the defect pointed out in the background art. Specifically, the present invention provides a cement-loaded multi-scale silicon source composite anti-seepage grouting material and its preparation method. By constructing a micron-nano cross-scale synergistic reinforcement system, multi-level dense filling and multi-level hydration reaction reinforcement from nano to micron are achieved, which significantly improves the anti-seepage performance, mechanical properties and long-term durability of the material, while taking into account both economy and environmental protection.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution.

[0010] A cement-loaded multi-scale silicon source composite seepage-proof grouting material is prepared from ordinary silicate cement, micron-scale silicon source, nano-scale silicon source, sodium-based bentonite and water, with the following mass proportions in the aforementioned order: 77-92: 5-15: 0.3-0.7: 2-8: 70-90, and the sum of the mass proportions of the first four materials is 100; wherein, the sodium-based bentonite is a water-retaining agent.

[0011] Preferably, the particle size of the micron-scale silicon source is less than 0.075 mm; the average particle size of the nanoscale silicon source, ordinary silicate cement, and sodium-based bentonite is gradient-distributed. Specifically, the average particle size of the nanoscale silicon source is 15 nm to 30 nm, the average particle size of the ordinary silicate cement is 15 μm to 18 μm, and the average particle size of the sodium-based bentonite is 20 μm to 22 μm.

[0012] This invention also provides a method for preparing a cement-loaded multi-scale silicon source composite seepage-proof grouting material, comprising the following steps: Step 1: Calcine rice husks at 600℃~700℃ for 1.5 hours~2.5 hours. After calcination, allow them to cool naturally to room temperature. Then grind them and pass them through a 200-mesh sieve to obtain rice husk ash with a particle size of less than 0.075mm and rich in highly active amorphous silica. Use this rice husk ash as a micron-scale silicon source. Step 2: Using the rice husk ash obtained in Step 1 as raw material, nano-silica is prepared by acid washing-alkali hydrolysis-acid precipitation process, and the nano-silica is used as a nanoscale silicon source. Step 3: Place the nano-silica obtained in Step 2 and sodium-based bentonite in water and disperse them by ultrasonic dispersion to obtain a nano-modified suspension. Step 4: Dry mix ordinary silicate cement with rice husk ash obtained in Step 1 to obtain premixed dry powder. Step 5: Add the nano-modified suspension obtained in Step 3 to the premixed dry powder obtained in Step 4, and perform wet mixing using a mixing method of first low speed and then high speed to obtain cement-loaded multi-scale silicon source composite seepage prevention grouting material.

[0013] Preferably, the process for preparing nano-silica using the acid washing-alkali hydrolysis-acid precipitation process in step 2 is as follows: Step 2.1, pickling pretreatment After removing impurities and pulverizing the rice husk ash, pass it through an 80-120 mesh sieve. Wash it with water at 50-70℃ for 20-40 minutes, then add a 5%-15% hydrochloric acid solution. The mass-to-volume ratio of rice husk ash to hydrochloric acid solution is 1g:8mL-12mL. Stir and soak at 50-70℃ for 1-3 hours, then vacuum filter and wash with water until the washing solution is neutral. Finally, dry to obtain the acid-washed rice husk ash. Step 2.2, alkaline extraction The acid-washed rice husk ash was mixed with a sodium hydroxide solution with a concentration of 1.0 mol / L to 2.0 mol / L and a mass-to-volume ratio of 1 g: 5 mL to 8 mL. The mixture was kept boiling at a stirring speed of 200 r / min to 400 r / min for 2 to 3 hours, and then vacuum filtered to obtain a sodium silicate solution. Step 2.3, acid precipitation Add 0.5% to 1.2% of the total mass of a metal ion chelating agent to a sodium silicate solution and mature it at 50℃ to 70℃ for 20 to 40 minutes; then slowly add 0.8 mol / L to 1.5 mol / L hydrochloric acid solution to carry out a precipitation reaction, controlling the pH value at the end of the reaction to be 8 to 10, and obtain a white precipitate; Step 2.4, Post-processing The white precipitate is left to stand for 8 to 16 hours, then centrifuged and washed 3 to 5 times with deionized water or purified water until the washing solution is neutral. Finally, it is dried until the specified degree of dryness is reached. At this point, the preparation of nano-silica is complete.

[0014] Preferably, the specified dryness has a moisture content of less than 5%.

[0015] Preferably, the stirring speed and duration of wet stirring in step 5 using a low-speed-then-high-speed stirring method are as follows: the low-speed stirring speed is 100 rpm to 150 rpm and the duration is 1 minute to 2 minutes; the high-speed stirring speed is 400 rpm to 600 rpm and the duration is 3 minutes to 5 minutes.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention achieves hierarchical pore filling with excellent impermeability. The invention constructs a micron-nano two-dimensional pore filling system. Rice husk ash and sodium-based bentonite fill the micron-level capillary pores, while nano-silica fills the nano-level gel pores. This significantly reduces the porosity of the hardened slurry, refines the pore size, and reduces pore connectivity. Macroscopically, this results in a significantly reduced permeability coefficient and a greatly improved impermeability grade, making it highly suitable for engineering projects with stringent impermeability requirements.

[0017] 2. This invention achieves cross-scale synergistic enhancement, comprehensively improving impermeability. This invention constructs a cross-scale synergistic hydration reaction system. The nucleation effect of nano-silica at the micrometer scale ensures high early strength of the material, while the filling effect at the nanometer scale optimizes the gel pore structure. The filling effect of rice husk ash at the micrometer scale improves particle size distribution, while its pozzolanic reaction promotes the formation of dense hydrated calcium silicate gel at the nanometer scale.

[0018] 3. This invention improves the long-term durability of the material. Through the volcanic ash reaction, a large amount of the chemically unstable calcium hydroxide in the grout is consumed and transformed into a chemically stable and dense hydrated calcium silicate gel. This not only increases the density of the hardened body but also enhances its resistance to chemical attacks such as sulfate corrosion, thereby significantly improving the long-term durability of the grouting material.

[0019] 4. This invention meets the requirements of green building and has both economic and environmental benefits. This invention uses rice husk ash, a renewable agricultural waste, to prepare nano-silica, significantly reducing the carbon footprint and cost of grouting materials. The acid washing-alkali hydrolysis-acid precipitation process used is simple to operate, easy to control, and has mild reaction conditions, requiring no complex high-pressure or ultrasonic equipment. The resulting nano-silica has high purity (Si). With a content >93%, stable performance, and suitability for industrial production, rice husk ash is significantly cheaper than ordinary silicate cement and commercial nano-silica. Therefore, this invention effectively controls material costs while significantly improving performance. Detailed Implementation

[0020] The present invention will now be described in detail with reference to specific embodiments.

[0021] Example 1 A cement-loaded multi-scale silicon source composite seepage-proof grouting material is prepared from ordinary silicate cement, micron-scale silicon source, nano-scale silicon source, sodium-based bentonite and water, with the following mass proportions in the aforementioned order: 72-92: 5-15: 0.3-0.7: 2-8: 70-90, and the sum of the mass proportions of the first four materials is 100; wherein, the sodium-based bentonite is a water-retaining agent.

[0022] In this embodiment, the particle size of the micron-scale silicon source is less than 0.075 mm; the average particle size of the nanoscale silicon source, ordinary silicate cement, and sodium-based bentonite is gradient-distributed. Specifically, the average particle size of the nanoscale silicon source is 15 nm to 30 nm, the average particle size of the ordinary silicate cement is 15 μm to 18 μm, and the average particle size of the sodium-based bentonite is 20 μm to 22 μm.

[0023] In specific implementation, the mass fractions of ordinary silicate cement, micron-scale silicon source, nano-scale silicon source, sodium-based bentonite, and water are in the aforementioned order of 78.5:15:0.5:6:80. That is, the water-cement ratio of the cement-loaded multi-scale silicon source composite seepage-proof grouting material described in Example 1 of this invention is 0.8.

[0024] A method for preparing a cement-loaded multi-scale silicon source composite seepage-proof grouting material includes the following steps: Step 1: Calcine rice husks at 600℃~700℃ for 1.5 hours~2.5 hours. After calcination, allow them to cool naturally to room temperature. Then grind them and pass them through a 200-mesh sieve to obtain rice husk ash with a particle size of less than 0.075mm and rich in highly active amorphous silica. Use this rice husk ash as a micron-scale silicon source.

[0025] In this embodiment, the calcination temperature is 650℃ and the calcination time is 2.0 hours. The mechanical grinding is performed using a planetary ball mill, and the grinding time is 30 minutes.

[0026] Step 2: Using the rice husk ash obtained in Step 1 as raw material, nano-silica is prepared by acid washing-alkali hydrolysis-acid precipitation process, and the nano-silica is used as a nanoscale silicon source.

[0027] In this embodiment, the process of preparing nano-silica using the acid washing-alkali hydrolysis-acid precipitation process is as follows: Step 2.1, pickling pretreatment After removing impurities and pulverizing the rice husk ash, pass it through an 80-120 mesh sieve. Wash it with water at 50-70℃ for 20-40 minutes, then add a 5%-15% hydrochloric acid solution. The mass-to-volume ratio of rice husk ash to hydrochloric acid solution is 1g:8mL-12mL. Stir and soak at 50-70℃ for 1-3 hours, then vacuum filter and wash with water until the washing solution is neutral. Finally, dry to obtain the acid-washed rice husk ash.

[0028] The purpose of this step is to remove impurities and trace metal elements from the rice husk ash. In practice, the sieve is 100 mesh, the washing temperature is 60℃, the time is 30 minutes, and then a 10% hydrochloric acid solution is added. The mass-to-volume ratio of rice husk ash to hydrochloric acid solution is 1g:10mL. The stirring temperature is 60℃, and the stirring and soaking time is 2 hours.

[0029] Step 2.2, alkaline extraction

[0030] The acid-washed rice husk ash was mixed with a sodium hydroxide solution with a concentration of 1.0 mol / L to 2.0 mol / L and a mass-to-volume ratio of 1 g: 5 mL to 8 mL. The mixture was kept boiling for 2 to 3 hours at a stirring speed of 200 r / min to 400 r / min, and then vacuum filtered to obtain a sodium silicate solution.

[0031] In the specific implementation, the concentration of sodium hydroxide solution was 1.5 mol / L, and the mass-to-volume ratio of rice husk ash to sodium hydroxide solution was 1 g: 6 mL. The stirring speed was 300 r / min, and boiling was maintained for 2.5 hours.

[0032] Step 2.3, acid precipitation

[0033] Add 0.5% to 1.2% of the total mass of a metal ion chelating agent to a sodium silicate solution and mature it at 50℃ to 70℃ for 20 to 40 minutes. Then, slowly add 0.8 mol / L to 1.5 mol / L hydrochloric acid solution to carry out a precipitation reaction, controlling the pH value at the end of the reaction to be 8 to 10, and obtain a white precipitate.

[0034] In the specific implementation, 0.8% of the total mass of the sodium silicate solution was added as a metal ion chelating agent, the aging temperature was 60℃, and the aging time was 30 minutes. Then, a 1.2 mol / L hydrochloric acid solution was slowly added dropwise to carry out the precipitation reaction, and the final pH value of the reaction was 9.

[0035] Step 2.4, Post-processing

[0036] The white precipitate is left to stand for 8 to 16 hours, then centrifuged and washed 3 to 5 times with deionized water or purified water until the washing solution is neutral. Finally, it is dried until the specified degree of dryness is reached. At this point, the preparation of nano-silica is complete.

[0037] In practice, the aging time is 12 hours. The moisture content at the specified dryness level is less than 5%.

[0038] Step 3: Place the nano-silica obtained in Step 2 and sodium-based bentonite in water and disperse them by ultrasonic dispersion to obtain a nano-modified suspension.

[0039] Step 4: Dry mix ordinary silicate cement with rice husk ash obtained in Step 1 to obtain premixed dry powder.

[0040] Step 5: Add the nano-modified suspension obtained in Step 3 to the premixed dry powder obtained in Step 4, and perform wet mixing using a mixing method of first low speed and then high speed to obtain cement-loaded multi-scale silicon source composite seepage prevention grouting material.

[0041] The stirring speed and duration for wet stirring in step 5 using a low-speed-then-high-speed stirring method are as follows: low-speed stirring speed is 100rpm-150rpm and duration is 1 minute-2 minutes; high-speed stirring speed is 400rpm-600rpm and duration is 3 minutes-5 minutes.

[0042] In practice, the low-speed stirring speed is 120 rpm for 2 minutes, and the high-speed stirring speed is 500 rpm for 4 minutes.

[0043] To make a comparison, three comparative examples were introduced.

[0044] Comparative Example 1 This comparative example provides a reference group of ordinary silicate cement slurry, whose raw material proportions by weight are: 100 parts ordinary silicate cement, 80 parts water, and a water-cement ratio of 0.8.

[0045] Comparative Example 2 This comparative example provides a control group of ordinary silicate cement + rice husk ash-based slurry, with the following raw material proportions by weight: 85 parts ordinary silicate cement, 15 parts rice husk ash, and 80 parts water, with a water-cement ratio of 0.8. The rice husk ash is prepared according to the method in Example 1.

[0046] Comparative Example 3 This comparative example provides a control group of ordinary silicate cement + rice husk ash + bentonite slurry, with the following raw material proportions by weight: 79 parts ordinary silicate cement, 15 parts rice husk ash, 6 parts sodium-based bentonite, and 80 parts water, with a water-cement ratio of 0.8. The rice husk ash is prepared according to the method in Example 1.

[0047] The ordinary silicate cement used in Example 1 and the three comparative examples was PO42.5R.

[0048] To demonstrate the beneficial effects of the present invention, performance tests were conducted on the hardened grouts prepared in Example 1 and Comparative Examples 1-3. All specimens were molded using standard molds and cured to the specified age under standard curing conditions. Specifically, the grouts of the seepage-proof grouting materials prepared in Example 1 and Comparative Examples 1-3 were injected into standard molds and cured to the specified age under standard curing conditions: temperature 20±2℃ and relative humidity not less than 95%. Performance tests were then performed. The test results are summarized in the table below.

[0049] Table 1: Comparison of Mechanical and Durability Properties of Hardened Paste

[0050] The data shows that, compared to the control group of pure ordinary Portland cement in Comparative Example 1, the 28-day compressive strength of Example 1 decreased from 14.41 MPa to 11.37 MPa, a decrease of approximately 21.1%, but the impermeability was significantly improved: the permeability coefficient decreased from 1.14 × 10⁻⁶ MPa. mm / s decreased to 9.43 × 1 mm / s, a decrease of 91.7%, reaching 1 The permeability level is orders of magnitude lower. The bleeding rate of Example 1 was 1.5%, while that of Comparative Example 1 was as high as 9.1%. The huge difference in slurry stability directly determines the microstructure quality of the hardened body: high bleeding rate leads to uneven component distribution and the formation of interconnected pores; while low bleeding rate ensures uniform component distribution and constructs a dense seepage barrier.

[0051] Comparing Example 1 and Comparative Example 2, the 28-day compressive strength of Example 1 was 11.37 MPa, which was 25.9% lower than that of Comparative Example 2 (15.34 MPa). However, it showed a significant advantage in impermeability: the permeability coefficient was 9.43 × 10⁻⁶. mm / s, far lower than the 7.55 × 10⁻⁶ mm / s of Comparative Example 2. The flow rate decreased by 87.5% to mm / s. The bleeding rate of Example 1 was 1.5%, while that of Comparative Example 2 was 6.0%, highlighting the limitations of single modification methods. Although Comparative Example 2 incorporated micron-sized rice husk ash, the lack of bentonite and nano-silica resulted in insufficient slurry stability, with microscopic defects within the hardened body becoming seepage channels. In contrast, Example 1, through the synergistic effect of bentonite and nano-silica, significantly improved slurry stability and the density of the hardened body.

[0052] Compared with Comparative Example 1 and Comparative Example 3, the 28-day compressive strength of Example 1 was 11.37 MPa, which was slightly improved (6.1%) compared with 10.72 MPa of Comparative Example 3, but the impermeability was further optimized: the permeability coefficient was 9.43 × 10⁻⁶. mm / s, compared to 3.16 × 1 in Comparative Example 3 The flow rate decreased by 70.2% to mm / s. The bleeding rate of Example 1 was 1.5%, while that of Comparative Example 3 was 3.0%. Comparative Example 3 already possessed the micron-level filling effect of rice husk ash and the thickening and water-retaining effect of bentonite, but the impermeability was significantly improved after introducing 0.5 parts of nano-silica in Example 1. Nano-silica, with its nanoscale particle size, filled the ultrafine pores, and its huge specific surface area enhanced the water retention capacity of the slurry. In synergy with bentonite, it further improved the density of the hardened body.

[0053] In summary, this invention constructs a synergistic system that combines micron-sized rice husk ash, nano-sized silica, and bentonite in a multi-component compound, exhibiting physical filling, pozzolanic effect, nano-reinforcement, and thickening and water retention. The synergistic effect of these three components reduces the permeability coefficient to 9.43 × 10⁻⁶. The strength of Example 1 is 91.7% lower than that of the baseline group, representing a reduction of 91.7%. Although the 28-day compressive strength of Example 1 is slightly lower than that of some comparative examples, it still meets engineering requirements. For seepage-proof grouting materials, seepage resistance is a more critical core indicator than strength. The overwhelming advantage of Example 1 in this indicator makes its overall performance far superior to all comparative examples, and it has broad application prospects in the field of underground and hydraulic engineering.

Claims

1. A cement-loaded multi-scale silicon source composite seepage-proof grouting material, characterized in that, It is composed of ordinary silicate cement, micron-scale silicon source, nano-scale silicon source, sodium-based bentonite and water, with the following mass proportions in the aforementioned order: 77-92: 5-15: 0.3-0.7: 2-8: 70-90, and the sum of the mass proportions of the first four materials is 100; wherein, the sodium-based bentonite is a water-retaining agent.

2. The cement-loaded multi-scale silicon source composite seepage-proof grouting material according to claim 1, characterized in that, The particle size of the micron-scale silicon source is less than 0.075 mm; the average particle size of the nanoscale silicon source, ordinary silicate cement, and sodium-based bentonite is gradient-distributed. Specifically, the average particle size of the nanoscale silicon source is 15 nm to 30 nm, the average particle size of the ordinary silicate cement is 15 μm to 18 μm, and the average particle size of the sodium-based bentonite is 20 μm to 22 μm.

3. A method for preparing a cement-loaded multi-scale silicon source composite seepage-proof grouting material, applicable to the cement-loaded multi-scale silicon source composite seepage-proof grouting material according to any one of claims 1-2, characterized in that, Includes the following steps: Step 1: Calcine rice husks at 600℃~700℃ for 1.5 hours~2.5 hours. After calcination, allow them to cool naturally to room temperature. Then grind them and pass them through a 200-mesh sieve to obtain rice husk ash with a particle size of less than 0.075mm and rich in highly active amorphous silica. Use this rice husk ash as a micron-scale silicon source. Step 2: Using the rice husk ash obtained in Step 1 as raw material, nano-silica is prepared by acid washing-alkali hydrolysis-acid precipitation process, and the nano-silica is used as a nanoscale silicon source. Step 3: Place the nano-silica obtained in Step 2 and sodium-based bentonite in water and disperse them by ultrasonic dispersion to obtain a nano-modified suspension. Step 4: Dry mix ordinary silicate cement with rice husk ash obtained in Step 1 to obtain premixed dry powder. Step 5: Add the nano-modified suspension obtained in Step 3 to the premixed dry powder obtained in Step 4, and perform wet mixing using a mixing method of first low speed and then high speed to obtain cement-loaded multi-scale silicon source composite seepage prevention grouting material.

4. The preparation method of a cement-loaded multi-scale silicon source composite seepage-proof grouting material according to claim 3, characterized in that, The process for preparing nano-silica using the acid washing-alkali hydrolysis-acid precipitation process described in step 2 is as follows: Step 2.1, pickling pretreatment After removing impurities and pulverizing the rice husk ash, pass it through an 80-120 mesh sieve. Wash it with water at 50-70℃ for 20-40 minutes, then add a 5%-15% hydrochloric acid solution. The mass-to-volume ratio of rice husk ash to hydrochloric acid solution is 1g:8mL-12mL. Stir and soak at 50-70℃ for 1-3 hours, then vacuum filter and wash with water until the washing solution is neutral. Finally, dry to obtain the acid-washed rice husk ash. Step 2.2, alkaline extraction The acid-washed rice husk ash was mixed with a sodium hydroxide solution with a concentration of 1.0 mol / L to 2.0 mol / L and a mass-to-volume ratio of 1 g: 5 mL to 8 mL. The mixture was kept boiling at a stirring speed of 200 r / min to 400 r / min for 2 to 3 hours, and then vacuum filtered to obtain a sodium silicate solution. Step 2.3, acid precipitation Add 0.5% to 1.2% of the total mass of a metal ion chelating agent to a sodium silicate solution and mature it at 50℃ to 70℃ for 20 to 40 minutes; then slowly add 0.8 mol / L to 1.5 mol / L hydrochloric acid solution to carry out a precipitation reaction, controlling the pH value at the end of the reaction to be 8 to 10, and obtain a white precipitate; Step 2.4, Post-processing The white precipitate is left to stand for 8 to 16 hours, then centrifuged and washed 3 to 5 times with deionized water or purified water until the washing solution is neutral. Finally, it is dried until the specified degree of dryness is reached. At this point, the preparation of nano-silica is complete.

5. The preparation method of a cement-loaded multi-scale silicon source composite seepage-proof grouting material according to claim 4, characterized in that, The specified dryness level refers to a moisture content of less than 5%.

6. The preparation method of a cement-loaded multi-scale silicon source composite seepage-proof grouting material according to claim 3, characterized in that, The stirring speed and duration for wet stirring in step 5 using a low-speed-then-high-speed stirring method are as follows: low-speed stirring speed is 100rpm-150rpm and duration is 1 minute-2 minutes; high-speed stirring speed is 400rpm-600rpm and duration is 3 minutes-5 minutes.

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