A new type of early strength water agent for sprayed concrete and a preparation method thereof

Abstract

The application discloses a novel early-strength water agent for sprayed concrete and a preparation method thereof, and belongs to the technical field of concrete synergist of building materials, and comprises the following raw materials in mass fractions: 6-9 parts of attapulgite, 0.6-1.8 parts of mineral powder, 0.3-0.9 parts of silicon powder, 0.1-0.3 parts of fly ash, 0.5-0.9 parts of sodium silicate, 0.1-0.3 parts of acrylic acid substance, 1-2 parts of water-based ethylene bis-stearamide emulsion, 3-5 parts of heavy calcium stone powder and 4-6 parts of water. The novel early-strength water agent for sprayed concrete and the preparation method thereof can effectively reduce the rebound rate of sprayed concrete in tunnel construction and have better strength than conventional products, and have a good engineering application foundation; meanwhile, the early-strength water agent has a low mixing amount, can save engineering cost, can reduce environmental pollution and has remarkable social and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of concrete enhancers for building materials, and in particular to a novel thickening and early-strength water-based agent for shotcrete and its preparation method. Background Technology

[0002] Thickening and early-strength water-based agents are a new type of cement concrete synergist. They not only increase the cohesiveness and adhesion of shotcrete, but also reduce the rebound rate, facilitating construction and use. Therefore, they are increasingly being used in shotcrete construction. Currently, railway tunnels in my country generally adopt composite lining structure systems, and shotcrete is an important component of the initial support structure in this system, serving as the first barrier directly contacting the corrosive media in the surrounding rock. Therefore, the construction and service performance of shotcrete is crucial to railway tunnel construction. In railway tunnel engineering, the rebound rate of shotcrete is generally around 30%, but under extreme conditions such as high surrounding rock grade, soft rock with large deformation, and water-rich areas, the rebound rate can reach as high as 50%. This not only seriously affects the tunnel construction process but also causes waste of raw materials and environmental pollution. Therefore, adding superior thickening and early-strength water-based agents to reduce the rebound rate of shotcrete can effectively improve the construction efficiency of railway tunnel engineering, reduce material loss, and has significant practical value and socio-economic benefits.

[0003] Patent CN91107273.X discloses a 5% by weight aqueous solution with a viscosity of 0.60-7.00 at 25°C, prepared by polymerization of acrylamide, acrylic acid, and acrylonitrile monomers. The thickening agent reacts at a temperature of 30-70°C. The duration is 2-6 hours, followed by 50-70 minutes. The neutralization and hydrolysis reaction is carried out at a lower temperature. The tackifying agent described in this patent has a high reaction temperature and a long reaction time, which is difficult to implement in actual engineering and increases costs. In contrast, the tackifying and early-strength agent described in this patent can be prepared by stirring at room temperature, which is convenient for application in actual engineering. Patent CN202211622392.6 proposes a sprayable early-strength mortar concrete system, in which an aqueous solution of a composite of water-based polymer emulsion, water-based epoxy, and polyvinyl alcohol 1799 is used as a tackifier, and inorganic lithium acetate is used as an early-strength agent. Patent CN202111375044.9 proposes a sprayable concrete viscosity modifier using 50-70% polycarboxylate superplasticizer mother liquor, 4-20% hydroxypropyl methylcellulose, 0-2% bentonite, and 6-20% alkanolamine.

[0004] Both of the aforementioned patents consider using organic composite materials as thickeners and reinforcing agents, which can effectively strengthen concrete. However, chemical composite materials are expensive, and their large-scale use can have a certain impact on the environment. The thickener and early-strength water-based agent described in this patent uses inorganic materials such as attapulgite clay, mineral powder, fly ash, and heavy calcium carbonate powder. These raw materials are inexpensive and readily available, ensuring both effective concrete reinforcement and cost-effectiveness while also being environmentally friendly. Patent CN202210685126.1 proposes a thickener for shotcrete, comprising 45-60% ultrafine mineral powder, 30-45% fly ash, 1-5% lignin fiber, and 1-5% resin fiber. This patent considers using mineral powder and fly ash combined with fibers as a thickener. To ensure application effectiveness, the dosage is relatively large, resulting in high cost, and the fibers are difficult to mix evenly, making practical application inconvenient. Summary of the Invention

[0005] The purpose of this invention is to provide a novel thickening and early-strength water-based agent for shotcrete and its preparation method. This agent can effectively reduce the rebound rate of shotcrete in tunnel construction and has a strength superior to conventional products, thus possessing a good foundation for engineering applications. It can meet the requirements for water-based agent preparation through a simple crushing process, achieving optimized resource reuse. Moreover, the preparation process is simple to operate and can be mass-produced, showing good commercial prospects. At the same time, the thickening and early-strength water-based agent has a low admixture dosage, which can save engineering costs and reduce environmental pollution, resulting in significant socio-economic benefits.

[0006] To achieve the above objectives, the present invention provides a novel thickening and early-strength water-based agent for shotcrete, comprising the following raw materials by weight: 6-9 parts attapulgite clay, 0.6-1.8 parts mineral powder, 0.3-0.9 parts silica fume, 0.1-0.3 parts fly ash, 0.5-0.9 parts sodium silicate, 0.1-0.3 parts acrylic acid, 1-2 parts water-based ethylene bis-stearamide emulsion, 3-5 parts heavy calcium carbonate powder, and 4-6 parts water.

[0007] Preferably, the acrylic substance is one or a mixture of calcium acrylate or magnesium acrylate, or polyacrylamide.

[0008] This invention also provides a method for preparing a novel thickening and early-strength water-based agent for shotcrete, comprising the following steps: S1. Add attapulgite clay, mineral powder, silica powder, fly ash, sodium silicate and water to a mechanically and quickly mix at room temperature, then add acrylic acid and stir quickly, then reduce the speed and stir normally to maintain the stirring state to form a uniform thickening and early strength aqueous phase liquid for later use. S2. Add the aqueous ethylene bis-stearamide emulsion to the thickening and early-strength aqueous phase liquid and stir mechanically to form a thickening and early-strength aqueous suspension for later use. S3. Add heavy calcium carbonate powder to the thickening and early strength water-based agent suspension and stir thoroughly to obtain the thickening and early strength water-based agent.

[0009] Preferably, in S1, the mechanical rapid mixing speed at room temperature is 1000-1500 r / min, the mixing time is 2-5 min, the rapid stirring speed after adding acrylic substances is 600-1000 r / min, the rapid stirring time is 20-40 min, and the normal stirring speed is 100-250 r / min.

[0010] Preferably, in S2, the mechanical stirring speed is 300-500 r / min and the mechanical stirring time is 3-8 min.

[0011] Preferably, in S2, the particle size of attapulgite, mineral powder, silica fume, and fly ash is 200-400 mesh.

[0012] Preferably, in S2, the total mass ratio of attapulgite clay, mineral powder, silica powder, fly ash, sodium silicate, and acrylic acid to the mass ratio of the aqueous ethylene bis-stearamide emulsion is (3-4):1.

[0013] Preferably, in S3, the mass ratio of aqueous ethylene bis-stearamide emulsion to heavy calcium carbonate powder is 1:(1-2).

[0014] Therefore, the present invention employs the above-mentioned novel thickening and early-strength water-based agent for shotcrete and its preparation method, which has the following beneficial effects: (1) The shotcrete thickening and early strength water-based agent prepared using this technology can effectively solve the problem of high rebound rate of shotcrete in tunnel construction. At the same time, the concrete prepared with this thickening and early strength water-based agent has a higher strength than conventional shotcrete, and has a good engineering application background. (2) This invention only requires a simple processing technology (pulverization) to reduce the fineness of the powder to meet the requirements of aqueous formulation, and can realize the optimized utilization of resources; (3) The implementation method is simple to operate. It only requires mixing attapulgite clay, mineral powder, silica powder, fly ash, sodium silicate, acrylic substances, water-based ethylene bis-stearamide emulsion, heavy calcium carbonate powder and water in proportion to prepare an industrial product, realize large-scale production, and has good commercial prospects. (4) The amount of thickening and early strength water-based agent in this invention is relatively low, which can effectively save engineering costs, reduce environmental pollution, and have significant social and economic benefits.

[0015] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0016] The technical solution of the present invention will be further described below through embodiments.

[0017] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0018] Example 1 This invention provides a novel thickening and early-strength water-based agent for shotcrete, comprising the following raw materials by weight: 6 parts attapulgite clay, 0.6 parts mineral powder, 0.3 parts silica fume, 0.1 parts fly ash, 0.5 parts sodium silicate, 0.1 parts acrylic acid, 1 part water-based ethylene bis-stearamide emulsion, 3 parts heavy calcium carbonate powder, and 4 parts water.

[0019] This invention also provides a method for preparing a novel thickening and early-strength water-based agent for shotcrete, comprising the following steps: S1. Add attapulgite clay, mineral powder, silica powder, fly ash, sodium silicate and water to room temperature and mechanically mix at 1200 r / min for 3 min. Then add acrylic acid and stir rapidly at 800 r / min for 40 min. After that, reduce the speed to 200 r / min and stir normally to form a uniform thickening and early strength aqueous phase for later use. S2. Add the aqueous ethylene bis-stearamide emulsion to the thickening and early-strength aqueous phase and mechanically stir at 400 r / min for 5 min to form a thickening and early-strength aqueous suspension for later use. S3. Add heavy calcium carbonate powder to the thickening and early strength water-based agent suspension and stir thoroughly to obtain the thickening and early strength water-based agent.

[0020] The prepared thickening and early-strength water-based agent was applied to concrete. A parallel comparative test of sprayed concrete with thickening and early-strength water-based agent was conducted on-site. The part most prone to rebound during the spraying construction (arch top) was selected. The test volume was 2 cubic meters. The fallen concrete was collected on-site and converted into volume. The rebound rate was calculated. The results are shown in Table 1.

[0021] Table 1. Resilience of thickening and early-strength water-based agents with different doping amounts

[0022] Table 1 shows that the rebound rate of shotcrete prepared using the thickening and early-strength water-based agent of this invention was 8.1% after on-site test spraying. The thickening and early-strength water-based agent can effectively reduce the rebound rate of shotcrete. Under the same on-site test spraying conditions, the rebound rate was 25.5%, indicating that within the tested dosage range, the lower the dosage of the thickening and early-strength water-based agent (5-7.5 kg / m³), the better. 3 The more significant the rebound rate reduction within the specified range, the better the thickening and early-strength water-based agent can reduce concrete rebound in easily rebounding areas such as tunnel arches.

[0023] Example 2 This invention provides a novel thickening and early-strength water-based agent for shotcrete, comprising the following raw materials by weight: 8 parts attapulgite clay, 1.2 parts mineral powder, 0.6 parts silica fume, 0.2 parts fly ash, 0.7 parts sodium silicate, 0.2 parts acrylic epoxy resin, 2 parts water-based ethylene bis-stearamide emulsion, 4 parts heavy calcium carbonate powder, and 5 parts water.

[0024] This invention also provides a method for preparing a novel thickening and early-strength water-based agent for shotcrete, comprising the following steps: S1. Add attapulgite clay, mineral powder, silica powder, fly ash, sodium silicate and water to room temperature and mechanically mix at 1200 r / min for 3 min. Then add acrylic acid and stir rapidly at 800 r / min for 40 min. After that, reduce the speed to 200 r / min and stir normally to form a uniform thickening and early strength aqueous phase for later use. S2. Add the aqueous ethylene bis-stearamide emulsion to the thickening and early-strength aqueous phase and mechanically stir at 400 r / min for 5 min to form a thickening and early-strength aqueous suspension for later use. S3. Add heavy calcium carbonate powder to the thickening and early strength water-based agent suspension and stir thoroughly to obtain the thickening and early strength water-based agent.

[0025] The prepared thickening and early-strength water-based agent was applied to concrete. A parallel comparative test of sprayed concrete with thickening and early-strength water-based agent was conducted on-site. The part most prone to rebound during the spraying construction (arch top) was selected. The test volume was 2 cubic meters. The fallen concrete was collected on-site and converted into volume. The rebound rate was calculated. The results are shown in Table 2.

[0026] Table 2. Resilience of thickening and early-strength water-based agents with different doping amounts

[0027] Table 2 shows that the rebound rate of shotcrete prepared using the thickening and early-strength water-based agent of this invention was 8.3% after on-site test spraying. The thickening and early-strength water-based agent can effectively reduce the rebound rate of shotcrete. After on-site test spraying under the same conditions, the rebound rate was 23.2%, indicating that within the experimental dosage range, the lower the dosage of the thickening and early-strength water-based agent (5-7.5 kg / m³), the better. 3 The more significant the rebound rate reduction within the specified range, the better the thickening and early-strength water-based agent can reduce concrete rebound in easily rebounding areas such as tunnel arches.

[0028] Example 3 This invention provides a novel thickening and early-strength water-based agent for shotcrete, comprising the following raw materials by weight: 9 parts attapulgite clay, 1.8 parts mineral powder, 0.9 parts silica fume, 0.3 parts fly ash, 0.9 parts sodium silicate, 0.3 parts acrylic epoxy resin, 2 parts water-based ethylene bis-stearamide emulsion, 5 parts heavy calcium carbonate powder, and 6 parts water.

[0029] This invention also provides a method for preparing a novel thickening and early-strength water-based agent for shotcrete, comprising the following steps: S1. Add attapulgite clay, mineral powder, silica powder, fly ash, sodium silicate and water to room temperature and mechanically mix at 1200 r / min for 3 min. Then add acrylic acid and stir rapidly at 800 r / min for 40 min. After that, reduce the speed to 200 r / min and stir normally to form a uniform thickening and early strength aqueous phase for later use. S2. Add the aqueous ethylene bis-stearamide emulsion to the thickening and early-strength aqueous phase and mechanically stir at 400 r / min for 5 min to form a thickening and early-strength aqueous suspension for later use. S3. Add heavy calcium carbonate powder to the thickening and early strength water-based agent suspension and stir thoroughly to obtain the thickening and early strength water-based agent.

[0030] The prepared thickening and early-strength water-based agent was applied to concrete. A parallel comparative test of sprayed concrete with thickening and early-strength water-based agent was conducted on-site. The part most prone to rebound during the spraying construction (arch top) was selected. The test volume was 2 cubic meters. The fallen concrete was collected on-site and converted into volume. The rebound rate was calculated. The results are shown in Table 3.

[0031] Table 3. Resilience of thickening and early-strength water-based agents with different doping amounts

[0032] Table 3 shows that the rebound rate of shotcrete prepared using the thickening and early-strength water-based agent of this invention was 8.0% after on-site test spraying. The thickening and early-strength water-based agent can effectively reduce the rebound rate of shotcrete. After on-site test spraying under the same conditions, the rebound rate was 26.2%, indicating that within the experimental dosage range, the lower the dosage of the thickening and early-strength water-based agent (5-7.5 kg / m³), the better. 3 The more significant the rebound rate reduction within the specified range, the better the thickening and early-strength water-based agent can reduce concrete rebound in easily rebounding areas such as tunnel arches.

[0033] Therefore, the present invention employs a novel thickening and early-strength water-based agent for shotcrete and its preparation method, which can effectively reduce the rebound rate of shotcrete in tunnel construction and has a strength superior to conventional products, thus possessing a good foundation for engineering applications. It can meet the requirements for water-based agent preparation through a simple crushing process, achieving optimized resource utilization. Furthermore, the preparation process is simple to operate and can be mass-produced, showing good commercial prospects. At the same time, the thickening and early-strength water-based agent has a low admixture dosage, which can save engineering costs and reduce environmental pollution, resulting in significant socio-economic benefits.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A novel thickening and early-strength water-based agent for shotcrete, characterized in that: The ingredients, by weight, include the following raw materials: 6-9 parts attapulgite, 0.6-1.8 parts mineral powder, 0.3-0.9 parts silica fume, 0.1-0.3 parts fly ash, 0.5-0.9 parts sodium silicate, 0.1-0.3 parts acrylic acid, 1-2 parts water-based ethylene bis-stearamide emulsion, 3-5 parts calcium carbonate powder, and 4-6 parts water.

2. The novel thickening and early-strength water-based agent for shotcrete according to claim 1, characterized in that: The acrylic substance is one or a mixture of calcium acrylate or magnesium acrylate, or polyacrylamide.

3. A method for preparing a novel thickening and early-strength water-based agent for shotcrete as described in any one of claims 1-2, characterized in that: Includes the following steps: S1. Add attapulgite clay, mineral powder, silica powder, fly ash, sodium silicate and water to a mechanically and quickly mix at room temperature, then add acrylic acid and stir quickly, then reduce the speed and stir normally to maintain the stirring state to form a uniform thickening and early strength aqueous phase liquid for later use. S2. Add the aqueous ethylene bis-stearamide emulsion to the thickening and early-strength aqueous phase liquid and stir mechanically to form a thickening and early-strength aqueous suspension for later use. S3. Add heavy calcium carbonate powder to the thickening and early strength water-based agent suspension and stir thoroughly to obtain the thickening and early strength water-based agent.

4. The method for preparing a novel thickening and early-strength water-based agent for shotcrete according to claim 3, characterized in that: In S1, the mechanical rapid mixing speed at room temperature is 1000-1500 r / min, and the mixing time is 2-5 min. After adding acrylic substances, the rapid stirring speed is 600-1000 r / min, and the rapid stirring time is 20-40 min. The normal stirring speed is 100-250 r / min.

5. The preparation method of a novel thickening and early-strength water-based agent for shotcrete according to claim 3, characterized in that: In S2, the mechanical stirring speed is 300-500 r / min, and the mechanical stirring time is 3-8 min.

6. The method for preparing a novel thickening and early-strength water-based agent for shotcrete according to claim 3, characterized in that: In S2, the particle size of attapulgite, mineral powder, silica fume, and fly ash is 200-400 mesh.

7. The method for preparing a novel thickening and early-strength water-based agent for shotcrete according to claim 3, characterized in that: In S2, the total mass ratio of attapulgite clay, mineral powder, silica powder, fly ash, sodium silicate, and acrylic acid to the mass ratio of water-based ethylene bis-stearamide emulsion is (3-4):

1.

8. The method for preparing a novel thickening and early-strength water-based agent for shotcrete according to claim 3, characterized in that: The mass ratio of aqueous ethylene bis-stearamide emulsion to heavy calcium carbonate powder is 1:(1-2).

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