Self-healing solid waste-based paste for dynamic microfractures, methods of making and using

Abstract

The present application belongs to the technical field of dynamic micro-crack treatment, and particularly relates to a self-repairing solid waste-based slurry for dynamic micro-cracks, a preparation method and a use method, which comprises the following raw materials: solid powder: composed of two or more of fly ash, gasification slag, steel slag, carbide slag, coal gangue and desulfurization gypsum; liquid raw material: composed of water and organic matter; the organic matter is one or more of benzyl lactate emulsion, methyl cellulose, polyvinyl alcohol, ethylene-vinyl acetate copolymer, dispersible latex powder, polyurethane and epoxy resin, etc. The multi-source coal-based solid waste forms a geopolymer three-dimensional network stable structure, and the addition of the organic matter forms a "tendon-bone" biomimetic tough structure, so that the anti-mining stress effect is achieved.

Description

Technical Field

[0001] This invention belongs to the field of dynamic microcrack treatment technology, specifically relating to self-healing solid waste-based slurry for dynamic microcracks, its preparation and application methods. Background Technology

[0002] Mine collapses, water inrushes, and gas leaks are dangerous sources that threaten miners' lives and disrupt coal supply. Backfilling the mine shaft with grouting material to seal leaks is a crucial means of preventing underground accidents. Among the many factors that cause underground accidents, dynamically developing micro-cracks are one of the safety hazards in coal mining engineering. Grouting and pressure-bearing reinforcement methods are generally used to avoid the problem of dynamic micro-crack formation.

[0003] CN116675498A discloses a grouting material for reinforcing cracks in mine floor slabs, made of cement, fly ash, clay, foaming agent, water-reducing agent, and water. It has good impermeability and viscosity time-varying properties. The cement-based grout has a long setting time and will dehydrate and shrink during the solidification process, resulting in microcracks.

[0004] CN112694314B discloses a grouting material for reinforcing rock mass fissures, which combines solid grouting materials such as cement, clay, and fly ash with chemical grouting materials such as polyurethane, water glass, and silicone. The polyurethane undergoes a chemical reaction and expands rapidly, thus sealing the pores. However, due to its low strength, it will still generate fissures in the mining environment and does not have self-healing ability.

[0005] CN114320220A discloses a construction method for repairing drilling fractures by combining CO2 foam and self-healing grout. The grout is composed of 95% ordinary Portland cement and 5% tetrasodium EDTA (a metal chelating agent). The cement grout solidified body has poor compatibility with the substrate, which can easily trigger secondary fractures in the downhole mining environment.

[0006] To eliminate the production risks caused by dynamic micro-gap, it is necessary to develop grouting materials that can adaptively repair dynamic micro-gap. Summary of the Invention

[0007] To address the aforementioned technical problems, one objective of this invention is to provide a self-healing solid waste-based slurry for dynamic microcracks, which exhibits adaptive repair properties for dynamic microcracks; another objective is to provide a method for preparing the self-healing solid waste-based slurry; and yet another objective is to provide a method for using the self-healing solid waste-based slurry.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A self-healing solid waste-based slurry for dynamic microcracks, comprising a plugging slurry and a pore-sealing slurry a6. The sealing slurry is sealing slurry a3, sealing slurry a4, or sealing slurry a5; The sealing slurry a3 is composed of solid powder, water, and organic matter; The sealing slurry a4 is composed of sealing slurry a3 and CO2; The sealing slurry a5 is composed of sealing slurry a3 and calcium salt seed crystals or of sealing slurry a4 and calcium salt seed crystals; The sealing slurry a6 is composed of sealing slurry a3 and an expansion agent.

[0009] The calcium salt seed crystals are made of anhydrous calcium sulfate or modified desulfurized gypsum.

[0010] The solid powder is composed of two or more of the following: fly ash, gasification slag, steel slag, carbide slag, coal gangue, and desulfurization gypsum. The organic material is one or more of the following: styrene-acrylic emulsion, methylcellulose, polyvinyl alcohol, ethylene-vinyl acetate copolymer, dispersible latex powder, polyurethane, and epoxy resin. The expanding agent is one or more of the following: calcium sulfoaluminate expanding agent, calcium oxide expanding agent, gypsum, expanding clay, and industrial aluminum powder.

[0011] By weight: the sealing slurry a3 is composed of 90-110 parts solid powder, 60-90 parts water and 0.5-5 parts organic matter; The sealing slurry a4 is composed of 90-110 parts of sealing slurry a3 and a certain amount of CO2; The sealing slurry a5 is composed of 90-110 parts of sealing slurry a4 and 1-10 parts of calcium salt seed crystals, or is composed of 100 parts of sealing slurry a3 and 1-8 parts of calcium salt seed crystals; The sealing slurry a6 is composed of 90-110 parts of sealing slurry a3 and 0.1-3 parts of expanding agent.

[0012] By weight: the solid powder consists of 50-70 parts fly ash, 20-30 parts carbide slag, and 5-10 parts desulfurized gypsum.

[0013] A preparation method, comprising the following steps: S1. Dry mix the solid waste powder evenly to obtain mixed dry material a1; S2. Mix the organic matter with water until homogeneous to obtain a2 mixture; S3. Add the mixed liquid a2 to the mixed dry material a1 and stir evenly to obtain the sealing slurry a3.

[0014] CO2 is introduced into the sealing slurry a3 and stirred thoroughly to obtain sealing slurry a4.

[0015] Add calcium salt seed crystals to the obtained sealing slurry a3 or sealing slurry a4, stir evenly, and obtain sealing slurry a5.

[0016] An expansion agent is added to the sealing slurry a3, and after stirring evenly, sealing slurry a6 is obtained.

[0017] A method for using a self-healing solid waste-based grout for dynamic micro-cracks involves drilling a hole near or through the crack as the grouting target area, injecting the prepared sealing grout a3, a4, or a5 into the hole using a high-pressure grouting gun, and indicating that the hole is full when the pressure is increased but injection is still not possible. Then, while pulling out the grouting pipe, the sealing grout a6 is injected until the hole is sealed.

[0018] Compared with the prior art, the beneficial effects of this invention are: Multi-source coal-based solid waste forms a stable three-dimensional network structure, and organic matter is added to form a biomimetic strong and tough structure of "muscle-bone" to achieve the effect of resisting mining stress. Industrial flue gas (containing CO2) is introduced into an organic-inorganic slurry. The grouting material can mineralize the CO2 in the flue gas to generate nano-CaCO3 crystals, which induce nucleation and growth on the inner wall of the fissure, tightly bond the bedrock, and fill the rock fissures. Moreover, the introduced CO2 microbubbles can also achieve the effect of easy gas injection. Calcium salt seed crystals are added to the slurry, utilizing their adaptive growth characteristics through dissolution and recrystallization to form an adaptive fracture-supporting structure. Furthermore, calcium ions form a bridging structure with the organic-inorganic material interface groups, achieving dynamic fracture interface compatibility and adhesion. Through the reinforcing and toughening effect of in-situ self-grown inorganic whiskers, the system can fill pores, promote hydration, and strengthen the structure.

[0019] Whiskers can fill the pores in the system, overlap with each other, and have a certain water storage capacity. In the early stage of the hydration reaction, whiskers absorb some of the water in the system, and release water in the later stage of the hydration reaction to maintain the hydration process of the system, thereby making the system hydration more thorough and the structure more compact. The better the sealing of the coating, the better the anti-corrosion performance. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the preparation method of the present invention; Figure 2 These are photographs and microscopic analysis diagrams of the mineralized grouting stone bodies of this invention; Figure 3 This is a scanning electron microscope image of the cross-section of the stone body in this invention; Figure 4 This is a schematic diagram of the grouting device of the present invention; Figure 5 These are longitudinal and transverse cut views of the grouting cylinder after curing according to the present invention; Figure 6This invention relates to the ultrasonic detection of the internal structure of the grouting material solidification body; Among them: 1 is a high-pressure grouting gun, and 2 is a transparent column. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] A self-healing solid waste-based slurry for dynamic microcracks includes a plugging slurry and a pore-sealing slurry a6; wherein the plugging slurry is plugging slurry a3, plugging slurry a4, or plugging slurry a5. Therefore, this self-healing solid waste-based slurry can be combined in the following ways: Method 1: Sealing grout a3 and hole sealing grout a6 The sealing slurry a3 is composed of solid powder, water and organic matter; the pore sealing slurry a6 is composed of sealing slurry a3 and an expansion agent.

[0023] Method 2: Sealing grout a4 and hole sealing grout a6 The sealing slurry a4 is composed of sealing slurry a3 and CO2; the pore-sealing slurry a6 is composed of sealing slurry a3 and an expansion agent.

[0024] Method 3: Sealing grout a5 and hole sealing grout a6 Sealing slurry a5 is composed of sealing slurry a3 and calcium salt seed crystals; pore sealing slurry a6 is composed of sealing slurry a3 and an expansion agent; Method 4: Sealing grout a5 and hole sealing grout a6 The sealing slurry a5 is composed of sealing slurry a4 and calcium salt seed crystals; the pore-sealing slurry a6 is composed of sealing slurry a3 and an expansion agent.

[0025] Furthermore, by weight: The aforementioned sealing slurry a3 is composed of 90-110 parts solid powder, 60-90 parts water, and 0.5-5 parts organic matter; The aforementioned sealing slurry a4 is composed of 90-110 parts of sealing slurry a3 and a certain amount of CO2; The aforementioned sealing slurry a5 is composed of 90-110 parts of sealing slurry a4 and 1-10 parts of calcium salt seed crystals, or is composed of 100 parts of sealing slurry a3 and 1-10 parts of calcium salt seed crystals; The above-mentioned sealing slurry a6 is composed of 90-110 parts of sealing slurry a3 and 0.1-3 parts of expansion agent.

[0026] Furthermore, the aforementioned solid powder is composed of two or more of the following: fly ash, gasification slag, steel slag, carbide slag, coal gangue, and desulfurization gypsum.

[0027] Furthermore, the aforementioned organic materials are one or more of the organic polymers such as styrene-acrylic emulsion, methylcellulose, polyvinyl alcohol, ethylene-vinyl acetate copolymer, dispersible latex powder, polyurethane, and epoxy resin.

[0028] Furthermore, the calcium salt seed crystals are anhydrous calcium sulfate or modified desulfurized gypsum; the expanding agent is one or more of the following: calcium sulfoaluminate expanding agent, calcium oxide expanding agent, gypsum, expanding clay, and industrial aluminum powder.

[0029] The solid waste-based slurry of the present invention has adaptive repair properties for dynamic micro-cracks. It adopts the above-mentioned multi-source coal-based solid waste to form a three-dimensional network stable structure and adds organic matter to form a "muscle-bone" biomimetic tough structure to achieve the effect of resisting mining stress.

[0030] By adding calcium salt seed crystals, their adaptive growth characteristics of dissolution and recrystallization are utilized to form an adaptive crack mutual support structure, and calcium ions form a bridging structure with organic-inorganic material interface groups, achieving the purpose of dynamic crack interface compatibility and adhesion.

[0031] A method for preparing self-healing solid waste-based slurry.

[0032] The specific preparation method is as follows: S1. Dry mix the solid waste powder evenly to obtain mixed dry material a1; S2. Mix the organic matter with water until homogeneous to obtain a2 mixture; S3. Add the mixed liquid a2 to the mixed dry material a1 and stir evenly to obtain the sealing slurry a3.

[0033] It can form an organic-inorganic composite cementitious slurry, creating a biomimetic strong and tough "muscle-bone" structure, achieving the effects of preventing curing shrinkage and resisting mining stress, and preventing secondary cracking after the slurry has cured.

[0034] Furthermore, CO2 is introduced into the sealing slurry a3 and stirred thoroughly to obtain sealing slurry a4.

[0035] Furthermore, the solid waste in step S1 includes two or more mixtures of solid powders such as fly ash, gasification slag, steel slag, carbide slag, coal gangue, and desulfurization gypsum; Preferably, the ingredients are 50-70 parts fly ash, 20-30 parts calcium carbide slag, and 5-10 parts desulfurized gypsum.

[0036] Furthermore, the organic matter in step S2 may include one or more organic polymers such as styrene-acrylic emulsion, methylcellulose, polyvinyl alcohol, ethylene-vinyl acetate copolymer, dispersible latex powder, polyurethane, and epoxy resin; Organic matter: 0.5-5 parts; Water: 60-90 parts; Preferably, the mixture consists of 1 part dispersible latex powder and 80 parts water; or 5 parts styrene-acrylic emulsion and 75 parts water.

[0037] Furthermore, the stirring speed of CO2 is controlled at 400-800 rpm, the mass flow rate of CO2 is 1-10 L / min, and the stirring is carried out for 10-60 minutes to ensure that microbubbles are evenly distributed in the slurry.

[0038] Preferably, the CO2 mass flow rate is 2 L / min, and the stirring time is 20-30 minutes. Furthermore, the CO2 introduced can be CO2-containing waste gas emitted from factories, thermal power plants, industrial equipment, etc.

[0039] During grouting, microbubbles can facilitate air intake and injection; the alkaline substances in the grout injected into the fissures react with CO2 in the flue gas to form calcium carbonate crystals, which can induce nucleation on the inner wall of the fissures to achieve adhesion and bonding to the bedrock.

[0040] Further, calcium salt seed crystals are added to the obtained sealing slurry a3 or sealing slurry a4, and stirred evenly to obtain sealing slurry a5.

[0041] Preferably, the amount of calcium salt seed crystals added is 1-8 parts; The mixing time should be controlled at 10-30 min, and the stirring speed at 500 r / min. The calcium salt seed crystals can be anhydrous calcium sulfate or modified desulfurized gypsum, etc., which have the function of in-situ self-growing inorganic whiskers; construct a self-growth environment to form a slurry with semi-intermediate calcium sulfate as filler, and then inject grout to form a dynamically solidified self-healing stone body, using crystal growth to achieve the purpose of bonding the bedrock within the gap and dynamic compatibility at the interface.

[0042] Further, an expansion agent is added to the sealing slurry a3, and after stirring evenly, sealing slurry a6 is obtained.

[0043] Furthermore, the expanding agent can be one or more of the following: calcium sulfoaluminate expanding agents, calcium oxide expanding agents, gypsum, expanded clay, industrial aluminum powder, etc. The amount of expanding agent added is 0.1-3 parts.

[0044] Preferably, the amount of industrial aluminum powder added is 0.1-0.2 parts, and it should be stirred with hot water at 60-70℃ before use.

[0045] The term "parts" refers to parts by weight; and by adding different raw materials in different steps, a variety of different slurries can be prepared, as detailed in the examples below.

[0046] Examples 1-3 (Organic-Inorganic Composite Cementitious Paste a3) Weigh out 64 parts of fly ash, 27 parts of calcium carbide slag, and 9 parts of desulfurized gypsum, and dry mix the various powders evenly in a mixer; weigh out 1 part of dispersible latex powder and 80 parts of water (Example 1). Weigh out 70 parts of fly ash, 30 parts of carbide slag, and 10 parts of desulfurized gypsum, and dry mix the powders evenly in a mixer; weigh out 5 parts of styrene-acrylic emulsion and 90 parts of water (Example 2). Weigh out 60 parts of fly ash, 20 parts of carbide slag, and 10 parts of desulfurized gypsum, and dry mix the powders evenly in a mixer; weigh out 3 parts of styrene-acrylic emulsion and 60 parts of water (Example 3). After stirring evenly in a container, add it to a mixer and stir evenly with the pre-mixed powder to obtain organic-inorganic composite cementitious slurry a3.

[0047] To demonstrate the role of organic matter in the slurry, a pure inorganic solid waste-based slurry (Example 4) was prepared, consisting of 64 parts fly ash, 27 parts calcium carbide slag, 9 parts desulfurized gypsum, and 80 parts water. The performance comparison between the two is shown in Table 1.

[0048] As shown in Table 1, the toughness of the organic-inorganic composite cementitious mortar modified with organic matter was significantly improved. Specifically, the flexural strength of the organic-inorganic composite cementitious mortar with added latex powder increased by 118%, and the bending strength increased by 30%. The flexural strength of the organic-inorganic composite cementitious mortar with added styrene-acrylic emulsion increased by 109%, and the bending strength increased by 25%. This is mainly because the network structure of the dispersible latex powder polymer in the cured organic-inorganic composite cementitious mortar system acts as an elastic link between the components in the system, and has the effect of fiber reinforcement and flexibility. It can effectively absorb the energy under impact to ensure that the material will not break, thereby improving the system structure and bending performance.

[0049] The composite gelling system with the addition of dispersible latex powder or styrene-acrylic emulsion has a large number of pores, which leads to a decrease in the density of the composite system of about 2%.

[0050] Example 5 (Mineralized CO2 foam slurry a4) In Example 1, the organic-inorganic composite gelling slurry a3 was transferred to the reactor, and CO2 was introduced into the reactor and stirred thoroughly. The stirring speed was controlled at 800 rpm and the mass flow rate of CO2 was 2 L / min. After stirring for 20 minutes, the solid waste-based CO2 foam slurry was obtained.

[0051] The compressive strength of the sample block from Example 1 (without CO2 mineralization) was 7.8 MPa after 3 days of curing and 11 MPa after 28 days, representing an increase of 41%. The compressive strength of the sample block from Example 4 (after CO2 mineralization) was 16.8 MPa after 3 days of curing and 25.4 MPa after 28 days, representing an increase of 51%, significantly higher than that of the unmineralized grouting material. This indicates that CO2 mineralization during the mixing process significantly improves the strength of the material.

[0052] Therefore, after 28 days of curing, due to the large amount of CO2 trapped during the slurry mixing process, the material undergoes continuous mineralization, thus exhibiting high mechanical properties. This method achieves efficient carbon sequestration while simultaneously realizing the resource utilization of industrial solid waste, producing low-carbon green building materials.

[0053] like Figure 2 As shown in Figure a, when the solidified specimen is placed in water, many bubbles are generated around the specimen. Figure 2 b shows that there are many uniform micropores at the interface after the solidified body is cut, indicating that a large amount of CO2 can be blocked under high rotation speed conditions. Figure 2 c shows the microstructure of the solidified stone, with a large amount of nano-calcium carbonate in the sample; and the cloud-like structure (hydration product) of the mineralized cementitious system and the microcrystalline nano-calcium carbonate structure permeate each other, making the internal structure of the stone compact and dense.

[0054] During the grouting process, the CO2 microbubbles sealed in the pores can continue to undergo subsequent mineralization reactions, achieving efficient CO2 fixation with an effective carbon fixation rate of up to 15%.

[0055] Examples 6-8 (Calcium Salt Seed Slurry a5) In Example 2, 1 part of anhydrous calcium sulfate was added (Example 6). In Example 2, 8 parts of anhydrous calcium sulfate (Example 7) were added, or in Example 4, 2 parts of pre-prepared 120... o C-dried desulfurized gypsum (Example 8). The mixing time should be controlled at 10-30 min, and the stirring speed at 500 r / min.

[0056] As shown in Table 2 below, the 3-day and 28-day compressive strengths of Example 6 are 13.6 MPa and 21.5 MPa, respectively; the 3-day and 28-day compressive strengths of Example 7 are 15.2 MPa and 23.6 MPa, respectively; and the 3-day and 28-day compressive strengths of Example 8 are 17.2 MPa and 25.6 MPa, respectively.

[0057] like Figure 3As shown, in-situ self-growing whiskers appeared in the 28-day stones of Examples 6-8, filling the pores and cracks in the original system and making the structure more compact. The increase in strength at 28 days compared to 3 days in the three examples was 58%, 55%, and 49%, respectively, indicating that the whiskers continued to grow, filling the structural defects inside the material, improving the microstructure of the material, and thus significantly improving the strength.

[0058] Examples 9-10 (Sealing slurry a6 - solid waste-based micro-expansion slurry) 0.1 parts of industrial aluminum powder were mixed with hot water at 65°C and then added to slurry a3 in Example 1. After thorough mixing, solid waste-based micro-expansion slurry a6 (Example 9) was obtained. The expansion rate of the solidified stone was 12.5%, and the 28-day compressive strength was 7.7 MPa.

[0059] Three parts of industrial aluminum powder were mixed with hot water at 65°C and then added to slurry a3 from Example 1. After thorough mixing, solid waste-based micro-expansion slurry a6 (Example 10) was obtained. The expansion rate of the solidified stone was 32.5%, and the 28-day compressive strength was 4.9 MPa.

[0060] This embodiment provides a method for using a self-healing solid waste-based slurry for dynamic microcracks.

[0061] Geological survey methods such as drilling and sonic logging are used to assess the development, size, and orientation of fractures. Areas near or passing through fractures are selected as grouting target areas for drilling. High-pressure grouting guns are used to inject sealing grout (a3, a4, or a5) into the holes. When increased pressure fails to inject further grout, the holes are considered full. Sealing grout (a6) is then injected while the grouting pipe is being withdrawn until the holes are sealed. The fracture filling effect is verified using borehole sampling analysis or non-destructive testing.

[0062] The specific operation is as follows: A high-pressure grouting gun is used in... Figure 4 The sealing grout a5 is injected into the transparent column of the grouting device (Example 6). When the pressure is increased but the grout cannot be injected, it means that the grouting is full. The sealing grout a6 is injected while the grouting pipe is being pulled out (Example 9) until the hole is sealed.

[0063] After the grout has solidified, the grouting cylinder is cut longitudinally and laterally. The morphology after cutting is shown in the figure below. Figure 5 As shown, the black areas represent the encapsulated coal gangue particles, and the white areas represent the solidified grouting material. The grouting material tightly encapsulates the coal gangue particles without any large voids, indicating that the grouting material has good fluidity and good cementing properties.

[0064] The test results were obtained using ultrasonic nondestructive testing. Figure 6As shown, the ultrasonic amplitude of the solidified stone body was found to be relatively regular, indicating that the internal structure of the filler was relatively dense and there were no obvious cracks or gaps.

[0065] The above description only illustrates preferred embodiments of the present invention, but the present invention is not limited to the above embodiments.

Claims

1. A self-healing solid waste-based slurry for dynamic microcracks, characterized in that, The self-healing solid waste-based slurry includes plugging slurry a5 and pore-sealing slurry a6. The sealing slurry a5 is composed of sealing slurry a3 and calcium salt seed crystals or of sealing slurry a4 and calcium salt seed crystals; The sealing slurry a3 is composed of solid powder, water, and organic matter; the sealing slurry a3 is composed of 90-110 parts of solid powder, 60-90 parts of water, and 0.5-5 parts of organic matter. The sealing slurry a4 is obtained by thoroughly stirring CO2 through sealing slurry a3; The sealing slurry a6 is composed of sealing slurry a3 and an expansion agent; The calcium salt seed crystals are made of anhydrous calcium sulfate or modified desulfurized gypsum. By weight: the solid powder consists of 50-70 parts fly ash, 20-30 parts calcium carbide slag, and 5-10 parts desulfurized gypsum; The organic material is one or more of the following: styrene-acrylic emulsion, methylcellulose, polyvinyl alcohol, ethylene-vinyl acetate copolymer, dispersible latex powder, polyurethane, and epoxy resin. The expanding agent is one or more of the following: calcium sulfoaluminate expanding agent, calcium oxide expanding agent, gypsum, expanding clay, and industrial aluminum powder.

2. The self-healing solid waste-based slurry for dynamic microcracks according to claim 1, characterized in that, By weight: The sealing slurry a5 is composed of 90-110 parts of sealing slurry a4 and 1-8 parts of calcium salt seed crystals, or is composed of 100 parts of sealing slurry a3 and 1-8 parts of calcium salt seed crystals; The sealing slurry a6 is composed of 90-110 parts of sealing slurry a3 and 0.1-3 parts of expanding agent.

3. A preparation method for the self-healing solid waste-based slurry according to claim 1 or 2, characterized in that, Includes the following steps: S1. Dry mix the solid waste powder evenly to obtain mixed dry material a1; S2. Mix the organic matter with water until homogeneous to obtain a2 mixture; S3. Add the mixture a2 to the dry mixture a1 and stir evenly to obtain the sealing slurry a3; CO2 was introduced into the sealing slurry a3 and stirred thoroughly to obtain sealing slurry a4; Add calcium salt seed crystals to the obtained sealing slurry a3 or sealing slurry a4, stir evenly, and obtain sealing slurry a5; An expansion agent is added to the sealing slurry a3, and after stirring evenly, sealing slurry a6 is obtained.

4. A method for using a self-healing solid waste-based slurry for dynamic microcracks, characterized in that: Select the area close to or through the crack as the target area for grouting and drill a hole. Use a high-pressure grouting gun to inject the sealing grout a5 prepared according to claim 3 into the hole. When the pressure is increased but it still cannot be injected, it means that it is full. While pulling out the grouting pipe, inject the sealing grout a6 until the hole is sealed.

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