Fine cement grouting material for seepage control of fine cracks of rock mass and preparation method of fine cement grouting material

Abstract

The invention discloses a fine cement grouting material for seepage control of fine cracks of rock mass. The fine cement grouting material comprises the following components in parts by weight: 100 parts of cement; 50 to 60 parts of water; 0.5 to 1.0 part of a water reducing agent JG; and 1-2 parts of a coagulant CK. The invention also discloses a preparation method of the composition. The grouting material has the main beneficial effects that the fineness of cement particles in the grouting material is reduced, the stability of slurry is enhanced, and the slurry can be effectively injected into fine cracks of rock mass; the viscosity of the slurry is reduced, and the fluidity of the grouting slurry is improved; the hydration reaction and the hydration speed are improved, the condensation of cement grout is promoted, the grouting time is shortened, and the working efficiency is improved; mechanical properties such as compressive strength and impermeability strength of a condensate after slurry solidification are improved; the grouting material can be prepared under the condition of normal temperature, the required energy consumption is low, and all the components are inorganic materials, so that the grouting material is pollution-free and excellent in environment-friendly performance; the hardened stone is high in strength, good in durability and wide in adaptability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of geotechnical engineering foundation anti-seepage and reinforcement grouting treatment, and particularly relates to a fine cement grouting material for rock mass micro-fissure seepage control and a preparation method thereof. BACKGROUND

[0002] The cement-based grouting material is the most widely used and largest amount of selected material in the current domestic and foreign geotechnical engineering rock mass fissure anti-seepage and reinforcement treatment. The most important factor affecting the grouting ability of the cement grouting material into the rock mass fissure is the geometric size (particle size) of the cement particles in the slurry. Reducing the particle size of the cement particles can expand the use range of the cement-based grouting material in the rock mass micro-fissure seepage control grouting engineering, replace the chemical grouting material, and reduce the adverse effects of the chemical material on the environment. The fine research of the grouting cement particles aims to reduce the particle size of the cement particles so that it can be grouted into the rock mass micro-fissure with a width less than 0.1 mm, and improve the groutability of the cement slurry material. By adding different additives to the cement slurry, the flowability of the slurry is improved, the stability of the cement suspension is enhanced, the setting time of the slurry is adjusted, the defects of the volume shrinkage of the cement slurry after solidification are overcome, and the mechanical properties and durability of the cement stone are improved.

[0003] Researches show that during the preparation of the fine cement grouting material, the preparation process has a great influence on the fineness of the cement particles, the material properties and the mechanical properties of the cement setting body. In the preparation process, by using different processes, adopting appropriate ways, and adding different proportions and types of additives to the slurry to control the slurry properties of the fine cement grouting material, the mechanical strength of the cement setting body can be improved. The fine cement slurry has good stability, good anti-seepage and reinforcement effects, similar groutability to the chemical slurry, no pollution, no aging, and the grouting material can be prepared on the engineering site, and is flexible to use.

[0004] The fine cement grouting material can be widely applied to the foundation anti-seepage curtain grouting, consolidation grouting and concrete crack repair of buildings in water conservancy, petroleum, transportation, mining, tunnel, subway and other geotechnical engineering, has excellent economy, and has a very wide application prospect.

[0005] The existing technology has the following problems: the particle size of the ordinary cement-based grouting material is large, which cannot be effectively grouted into the rock mass micro-fissure with a width less than 0.1 mm, thereby limiting the use range; if the chemical grouting material is used, there may be potential risks of environmental impact; the stability of the ordinary cement slurry with a high water-cement ratio is usually poor, which is not conducive to the groutability in the micro-fissure and also affects the grouting effect after long-distance transportation; the setting time of the ordinary cement slurry fluctuates in a large range, thereby affecting the construction efficiency; the cement stone produces shrinkage after solidification, thereby affecting the impermeability of the stone; and the existing slurry preparation process cannot effectively refine the cement particles in the slurry and control the particle size distribution. SUMMARY

[0006] This invention provides a fine cement grouting material for seepage control in micro-fractures of rock mass and its preparation method, which can effectively solve the problems of large particle size, insufficient hydration reaction, insufficient grout performance, and difficulty in accurately controlling the fineness of cement particles in existing preparation processes in ordinary cement grouting materials.

[0007] A fine cement grouting material for seepage control in micro-fractures of rock mass, comprising the following components by weight: 100 parts cement; 50-60 parts water; 0.5-1.0 parts water-reducing agent JG; and 1-2 parts accelerator CK.

[0008] Furthermore, the cement is ordinary Portland cement with a strength grade of 42.5.

[0009] Furthermore, the water-reducing agent is a JG naphthalene-based improved high-efficiency water-reducing agent.

[0010] Furthermore, the coagulant CK is an inorganic compound.

[0011] Furthermore, the fine cement slurry has high fluidity, with a slurry funnel viscosity of less than 30s.

[0012] Furthermore, the particle size D of the cement particles in the fine cement slurry 95 Less than 40 μm, average particle size D 50 It is 10–12 μm.

[0013] A method for preparing a fine cement grouting material for seepage control in micro-fractures of rock mass includes the following steps:

[0014] a. Pour 50-60 parts of water into a high-speed mixer, add 100 parts of cement at room temperature, mix at a speed of not less than 1200 rpm, and mix for 3-5 minutes;

[0015] b. Add 0.5 to 1.0 parts of water-reducing agent JG to a high-speed mixer and mix it thoroughly with the cement slurry for 1 to 3 minutes;

[0016] c. Discharge the cement slurry from the high-speed mixer into the cement mill, and let the cement slurry circulate and grind in the cement mill for 1 to 3 minutes;

[0017] d. Discharge the cement slurry from the cement mill into a low-speed mixer, add an appropriate amount of water to adjust the water-cement ratio to 2:1 to 3:1, and then mix at a low speed, with a mixing speed not exceeding 150 rpm and a mixing time of 5 to 10 minutes.

[0018] e. Add 1-2 parts of accelerator CK to the cement slurry in a low-speed mixer, and mix for at least 1 minute;

[0019] f. The fine cement slurry in the low-speed mixer is discharged into the storage tank and the reaction continues for 10-30 minutes to finally obtain the fine cement grouting material.

[0020] Furthermore, the cement is ordinary Portland cement with a strength grade of 42.5.

[0021] Furthermore, the water-reducing agent is a JG naphthalene-based improved high-efficiency water-reducing agent.

[0022] Furthermore, the coagulant CK is an inorganic compound.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] 1. This invention increases the contact area between cement particles and water by reducing and controlling the geometric size of cement particles in the grouting material, thereby accelerating the hydration rate and reaction process of the cement particles and promoting the formation of cement grout. Simultaneously, the refinement of the particles allows the silica fume hydration reaction to absorb excess moisture from the environment, resulting in a more complete hydration reaction, which is beneficial for the formation and continuous improvement of the later-stage strength of the grout. Furthermore, the generation of more aggregates through the silica fume hydration reaction enhances the impermeability of the hardened cement grout and its bonding strength with the interface between the cement grout and the fractured media through its filling effect.

[0025] 2. This invention improves the fluidity of fine cement grouting material by adding water-reducing agent JG. Because the hydrophilic groups in the water-reducing agent are highly polar, they can form an adsorption film on the surface of cement particles, combining with water molecules to form a stable water film. This water film effectively reduces the frictional resistance between cement particles, thereby improving the fluidity of the cement grout and significantly enhancing the permeability of the cement grouting material. Simultaneously, the addition of naphthalene-based water-reducing agent JG slows down the aggregation process of cement particles, allowing the grout to be transported over long distances, meeting the needs of filling deep cracks in the medium.

[0026] 3. This invention, through the addition of the setting accelerator CK, can precisely control the solidification process of cement slurry, regulate the setting time, and improve the early mechanical strength of the cementitious solidified body. CK introduces Cl... - It will decrease the solubility of Ca(OH)2 and increase the concentration of Ca²⁺ in the solution. + The concentration of CK allows Ca(OH)2 to reach supersaturation and precipitate more quickly, accelerating the consumption of C3A, shortening the induction period, accelerating the early hydration rate, and shortening the setting time. CK also accelerates the hydration of C3A and C3S, increasing the amount of hydration products (CSH gel, ettringite, salts, etc.) generated in the early stage (1-7 days), resulting in a denser aggregate structure and significantly improved early strength (by 20%-50%), ensuring the high performance of fine cement grouting materials.

[0027] 4. This invention utilizes a water-reducing agent solution added before mixing ordinary cement grout to fully leverage its ability to improve grout fluidity and effectively reduce the viscosity of the cement grout during the refining process. The water-reducing agent JG reacts with water molecules in advance, fully releasing its hydrophilic polarity and forming a drag-reducing water film on the surface of cement particles before refining. This enhances the fluidity of the grout and significantly reduces the adverse effects of decreased fluidity caused by prolonged grinding and temperature rise during the refining process. This ensures that the fluidity of the grout remains sufficient even when preparing high-concentration fine cement grouting materials with a water-cement ratio of 0.5 on a large scale, greatly improving the production efficiency of grouting materials.

[0028] 5. This invention achieves precise control over the setting time of grouting materials by adding a suitable accelerator CK when preparing fine cement grouts of different concentrations (0.6, 0.5, etc.). The timing of adding the accelerator CK during the preparation of fine cement grouting materials has a decisive impact on the fluidity of the grout. Adding it after the cement particles are refined allows for a more complete hydration reaction, and the increased particle surface area accelerates the reaction process, achieving the goal of controlling the grout setting time. This enables precise control over the diffusion range of the grout in the medium, improving grouting efficiency. The accelerator CK can regulate the length of the hydration reaction induction period in fine cement grouts of different concentrations, thereby ensuring the stability of the grout fluidity over long-distance transportation and guaranteeing the stability of the grouting material quality from the centralized grout preparation station to the grouting operation point.

[0029] 6. The fine cement grouting material prepared by this invention can have its fineness precisely controlled by adjusting the grinding time of cement particles, resulting in a normal particle size distribution in the grout. The average particle size D50 is only 10-12 μm, and D95 ​​is less than 40 μm. This allows it to be injected into media fissures with a width of less than 0.1 mm, significantly expanding the application range of cement grouting materials. It partially replaces chemical grouting materials, exhibits high environmental protection efficiency, excellent economic performance, and broad application prospects. The fine cement grouting material can be prepared on-site during grouting projects, has fewer requirements for external conditions, and can be used in most environments, demonstrating good adaptability. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the construction process for preparing fine cement grouting material for seepage control in rock micro-fractures in an example of the present invention.

[0031] The reference numerals in the figure are described below:

[0032] 1—High-speed mixer; 2—Cement mill; 3—Low-speed mixer; 4—Grouting pump; 5—Grouting hole. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The cement used in the following examples is PC 42.5 ordinary Portland cement produced by Huaxin Cement Co., Ltd.; the water-reducing agent JG is produced by Beijing Yejian Special Materials Co., Ltd.; and the accelerator CK is self-made.

[0035] Examples 1-4: A fine cement grouting material for seepage control in micro-fractures of rock mass, the proportions of each component are shown in Table 1.

[0036] Table 1. Mix proportions of fine cement grouting materials for seepage control in micro-fractures of rock mass

[0037]

[0038] Table 1 shows the weight ratio of each component raw material in the fine cement grouting material for seepage control in rock microfractures described in the example, and its preparation process is as follows: Figure 1 As shown, the method includes the following steps:

[0039] Add 50-60 parts of water to high-speed mixer 1, add 100 parts of cement at room temperature, mix at a speed of not less than 1200 rpm, and mix for 3-5 minutes.

[0040] Then add 1 part of water-reducing agent JG solution and mix it thoroughly with cement slurry for 1-3 minutes; discharge the cement slurry from the high-speed mixer into cement mill 2 and circulate and grind the cement slurry in the cement mill for 1.5 minutes;

[0041] The fine cement slurry in the cement mill is discharged into the low-speed mixer 3, and 0.5 to 1 part of accelerator CK is added to the fine cement slurry. The mixture is stirred continuously until CK is completely dissolved. The stirring time is not less than 1 minute to obtain the fine cement grouting material.

[0042] Table 2. Test results of fine cement slurry and aggregate properties

[0043]

[0044] As can be seen from Table 2, the fluidity, setting time, impermeability, compressive strength and elastic modulus of the grout in each example of the present invention all meet the relevant requirements in the "Specification for Cement Grouting Test of Hydraulic Structures" (SL / T62-2020). In particular, the fluidity, stability (water separation rate) and mechanical strength are all at a good level.

[0045] Specific observations of the formulation and performance test results of Examples PG-1 and SM-1, Examples PG-1 and SM-2, and Examples SM-1 and SM-3 revealed that adding 0.1% water-reducing agent significantly reduced the viscosity of the slurry, improving its fluidity. However, the water-reducing agent also prolonged the setting time of the slurry. The setting time of the slurry can be shortened by adding a setting accelerator, especially the initial setting time of the slurry is significantly shortened.

[0046] Specific observations of the strength performance test results of cement stone grout in Examples PG-1 and SM-1, Examples PG-1 and SM-2, and Examples SM-1 and SM-3 revealed that 1% water-reducing agent JG improved the impermeability and compressive strength of cement stone. The addition of accelerator CK also improved the 3-day early strength of cement stone, with the highest increase in impermeability strength being 16.6%, the highest increase in 3-day compressive strength being 25.7%, and the highest increase in 28-day compressive strength being 6.8%.

[0047] After repeated experiments, the applicant found that the following technical solution can achieve the expected results: a fine cement grouting material for seepage control in micro-fractures of rock mass, wherein the addition amount of each component by weight is: 100 parts cement; 50-60 parts water; 0.5-1.0 parts water-reducing agent JG; and 1-2 parts accelerator CK.

[0048] In summary, the fine cement grouting material for seepage control in rock micro-fractures of the present invention, due to the addition of water-reducing agents, setting accelerators, and changes in cement particle fineness, significantly improves the grouting properties, fluidity, stability, compressive strength, and impermeability of the cement grout compared to ordinary cement grouting materials. It is evident that the implementation effect of the present invention is good and has practical application and promotion value.

[0049] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A fine cement grouting material for seepage control in micro-fractures of rock mass, characterized in that, The components, by weight, are as follows: 100 parts cement; 50-60 parts water; 0.5-1.0 parts water-reducing agent JG; and 1-2 parts accelerator CK.

2. The fine cement grouting material for seepage control in micro-fractures of rock mass according to claim 1, characterized in that, The cement is ordinary Portland cement with a strength grade of 42.

5.

3. The fine cement grouting material for seepage control in micro-fractures of rock mass according to claim 1, characterized in that, The water-reducing agent is a JG naphthalene-based improved high-efficiency water-reducing agent.

4. The fine cement grouting material for seepage control in micro-fractures of rock mass according to claim 1, characterized in that, The coagulant CK is an inorganic compound.

5. The fine cement grouting material for seepage control in micro-fractures of rock mass according to claim 1, characterized in that, The fine cement slurry has high fluidity, and the viscosity of the slurry funnel is less than 30s.

6. The fine cement grouting material for seepage control in micro-fractures of rock mass according to claim 1, characterized in that, The cement particle size D in the fine cement slurry 95 Less than 40 μm, average particle size D 50 It is 10–12 μm.

7. A method for preparing a fine cement grouting material for seepage control in micro-fractures of rock mass, characterized in that, Includes the following steps: a. Pour 50-60 parts of water into a high-speed mixer, add 100 parts of cement at room temperature, mix at a speed of not less than 1200 rpm, and mix for 3-5 minutes; b. Add 0.5 to 1.0 parts of water-reducing agent JG to a high-speed mixer and mix it thoroughly with the cement slurry for 1 to 3 minutes; c. Discharge the cement slurry from the high-speed mixer into the cement mill, and let the cement slurry circulate and grind in the cement mill for 1 to 3 minutes; d. Discharge the cement slurry from the cement mill into a low-speed mixer, add an appropriate amount of water to adjust the water-cement ratio to 2:1 to 3:1, and then mix at a low speed, with a mixing speed not exceeding 150 rpm and a mixing time of 5 to 10 minutes. e. Add 1-2 parts of accelerator CK to the cement slurry in a low-speed mixer, and mix for at least 1 minute; f. The fine cement slurry in the low-speed mixer is discharged into the storage tank and the reaction continues for 10-30 minutes to finally obtain the fine cement grouting material.

8. The method for preparing a fine cement grouting material for seepage control in micro-fractures of rock mass according to claim 7, characterized in that, The cement is ordinary Portland cement with a strength grade of 42.

5.

9. The method for preparing a fine cement grouting material for seepage control in micro-fractures of rock mass according to claim 7, characterized in that, The water-reducing agent is a JG naphthalene-based improved high-efficiency water-reducing agent.

10. The method for preparing a fine cement grouting material for seepage control in micro-fractures of rock mass according to claim 7, characterized in that, The coagulant CK is an inorganic compound.

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