Anti-crack and anti-corrosion mass concrete for underground space and preparation method of anti-crack and anti-corrosion mass concrete

Abstract

The invention relates to the technical field of concrete, and particularly discloses underground space anti-crack and anti-corrosion mass concrete and a preparation method thereof. The invention discloses anti-crack and anti-corrosion mass concrete for underground space. The anti-crack and anti-corrosion mass concrete is prepared from 320 to 335 parts of cement, 76 to 88 parts of fly ash, 1025 to 1050 parts of coarse aggregate, 670 to 685 parts of fine aggregate, 11 to 15 parts of carbon fiber, 14 to 17 parts of graphite particles, 4 to 6 parts of anti-permeability agent, 2 to 3 parts of water reducing agent and 155 to 170 parts of water, the anti-permeability agent is prepared by mixing polyethylene glycol distearate, diethanolisopropanolamine and D-mannitol according to the mass ratio of (2 to 4): (1 to 2): (1 to 2). The mass concrete prepared by the invention has good crack resistance and erosion resistance, can effectively control the generation of cracks under the condition of not adding an expanding agent, and can be widely applied to underground space engineering such as underground stations, tunnels, basements and the like.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, and in particular to a large-volume concrete that is resistant to cracking and corrosion in underground spaces and a preparation method thereof. Background Art

[0002] Mass concrete refers to large-volume concrete with a minimum geometric size of no less than 1m, which has the characteristics of thick structure, large amount of concrete, complex engineering conditions and high construction technology requirements. Mass concrete is widely used in underground space projects, such as underground stations, tunnels, basements, etc.

[0003] Cracks are one of the diseases that are easy to occur in large-volume concrete. The reason is that large-volume concrete releases a large amount of hydration heat during the hardening process. However, due to the large structural size of large-volume concrete, this hydration heat is difficult to dissipate from the inside of the concrete, which causes the internal temperature of the large-volume concrete to rise and generate temperature stress. The heat dissipation on the surface of the concrete is fast, forming a temperature gradient, which in turn causes cracks. In addition, the underground space environment is complex and there are many corrosive media. When cracks appear in large-volume concrete, the corrosive media can easily spread from the cracks to the internal structure of the concrete, causing erosion of the concrete, thereby further exacerbating the damage to the internal structure of the large-volume concrete, seriously affecting the mechanical properties of the large-volume concrete, and shortening the service life of the large-volume concrete.

[0004] At present, it is common practice to add expansive agents to mass concrete to offset the shrinkage of concrete and reduce the formation of concrete cracks. However, the use of expansive agents is very strict, and the proportion of mass concrete and the amount of expansive agents added need to be precisely controlled. At the same time, the introduction of expansive agents increases the construction environment requirements and early maintenance difficulty of mass concrete. Operators who lack relevant experience may not be able to achieve the expected expansion effect, and may even cause excessive expansion of concrete, further exacerbating the formation of cracks. Therefore, it is necessary to develop a mass concrete that can reduce cracking without adding expansive agents. Summary of the invention

[0005] In order to solve the problem that large-volume concrete is prone to cracking, the present application provides an underground space anti-crack and anti-corrosion large-volume concrete and a preparation method thereof, so as to improve the crack resistance and erosion resistance of the large-volume concrete and extend its service life. The large-volume concrete prepared in the present application has good crack resistance and erosion resistance, and can effectively control the generation of cracks without adding an expansion agent. It can be widely used in underground space projects such as underground stations, tunnels, and basements to extend the service life of the project.

[0006] In the first aspect, the present application provides a large-volume concrete for underground space that is resistant to cracking and corrosion, and adopts the following technical solutions: A crack-resistant and corrosion-resistant large-volume concrete for underground spaces comprises, based on the mass proportion of the large-volume concrete, 320-335 parts of cement, 76-88 parts of fly ash, 1025-1050 parts of coarse aggregate, 670-685 parts of fine aggregate, 11-15 parts of carbon fiber, 14-17 parts of graphite particles, 4-6 parts of impermeability agent, 2-3 parts of water reducer and 155-170 parts of water; the impermeability agent is a mixture of polyethylene glycol distearate, diethanol monoisopropanolamine and D-mannitol in a mass ratio of (2-4):(1-2):(1-2).

[0007] In the above technical scheme, carbon fiber has good tensile strength and toughness, which significantly improves the crack resistance of concrete; while graphite particles have excellent thermal conductivity, cooperate with carbon fiber to form a three-dimensional thermal conductive network inside concrete, accelerate heat dissipation, significantly reduce the internal temperature gradient, thereby reducing the possibility of crack generation. At the same time, the polyethylene glycol distearate in the impermeability agent has good lubricity and dispersibility, can improve concrete construction performance, improve compactness and impermeability; diethanol monoisopropanolamine can improve cement dispersibility and concrete overall performance; D-mannitol regulates the setting time and enhances the mechanical strength of mass concrete. Through the synergistic effect of polyethylene glycol distearate, diethanol monoisopropanolamine and D-mannitol in the impermeability agent, the concrete pore structure is refined, the internal pore channel is blocked, and the compactness, impermeability and durability are improved. Based on the effects of the above components, the mass concrete prepared by the present application effectively controls crack generation without adding an expansion agent, and improves the crack resistance, erosion resistance and mechanical properties of mass concrete.

[0008] Preferably, the mass ratio of polyethylene glycol distearate, diethanol monoisopropanolamine and D-mannitol is 3.2:1.4:1.7.

[0009] In the above technical solution, the present application further improves the performance of the anti-seepage agent by optimizing the mass ratio of polyethylene glycol distearate, diethanol monoisopropanolamine and D-mannitol in the anti-seepage agent, thereby enhancing the crack resistance and erosion resistance of the concrete. This optimized ratio enables the anti-seepage agent to better refine the concrete pore structure, block the internal pore channels, and improve the density and durability of the concrete.

[0010] Preferably, based on the mass fraction of the mass concrete, 6 to 9 parts of modified cellulose fibers are added to the mass concrete, and the modified cellulose fibers are prepared by soaking cellulose fibers in a sodium polyacrylate solution and then drying them.

[0011] In the above technical solution, the invention further introduces modified cellulose fibers into large-volume concrete, thereby further improving the crack resistance of concrete. After the modified cellulose fibers are soaked in a sodium polyacrylate solution, a large amount of sodium polyacrylate molecules are adsorbed on their surfaces. These molecules can form a network structure in the concrete, enhancing the interfacial bonding between the fibers and the concrete matrix, thereby more effectively inhibiting the generation of cracks. At the same time, the water retention of sodium polyacrylate also helps to improve the construction performance of concrete.

[0012] Preferably, the preparation method of the modified cellulose fiber comprises: taking cellulose fiber, soaking it in a 5%wt sodium polyacrylate solution for 10 to 15 minutes, then taking it out and drying it to obtain modified cellulose fiber; the preparation method of the modified cellulose fiber comprises: taking cellulose fiber, soaking it in a 5%wt sodium polyacrylate solution for 10 to 15 minutes, then taking it out and drying it to obtain modified cellulose fiber; the mass ratio of the cellulose fiber to the 5%wt sodium polyacrylate solution is 1:(4 to 5).

[0013] In the above technical scheme, the present application provides a simple and easy method for preparing modified cellulose fibers. By controlling the immersion time of the cellulose fibers and the concentration of the sodium polyacrylate solution, the properties of the cellulose fibers can be modified, and the generation of cracks in large-volume concrete can be effectively inhibited.

[0014] Preferably, the water reducing agent is lignin sulfonate.

[0015] In the above technical solution, lignin sulfonate, as a commonly used concrete water reducer, can significantly reduce the water-cement ratio of concrete and improve the strength and durability of concrete. At the same time, lignin sulfonate also has a certain retarding effect. This application selects it as a water reducer for large-volume concrete, which also helps to improve the construction performance of concrete and further reduce the occurrence of cracks.

[0016] Preferably, the particle size of the fine aggregate is between 0.35 and 0.5 mm, the coarse aggregate is composed of fine crushed stone with a particle size between 5 and 17.5 mm and coarse crushed stone with a particle size between 21.5 and 37.5 mm, and the mass ratio of the fine crushed stone to the coarse crushed stone is 1:1.

[0017] In the above technical solution, the present application can improve the compactness and workability of concrete by optimizing the particle size and ratio of fine aggregate and coarse aggregate, thereby further improving the crack resistance and erosion resistance of concrete. At the same time, the appropriate particle size and ratio also help to improve the compressive strength and flexural strength of concrete.

[0018] Preferably, the particle size of the graphite particles is between 0.05 and 0.1 mm.

[0019] Preferably, the mass ratio of the carbon fibers to the graphite particles is (13-15):(14-15).

[0020] In the above technical solution, the present application controls the particle size of graphite particles between 0.05 and 0.1 mm, thereby ensuring that the graphite particles are evenly distributed in the concrete, giving full play to their thermal conductivity, accelerating the dissipation of heat inside the concrete, reducing the temperature gradient, and thus effectively inhibiting the generation of cracks.

[0021] Furthermore, by controlling the mass ratio of carbon fiber and graphite particles within a certain range, the present application can ensure that the two form a good synergistic effect in concrete and jointly improve the crack resistance and erosion resistance of concrete. The combined use of carbon fiber and graphite particles can not only enhance the tensile strength and toughness of concrete, but also accelerate the dissipation of heat inside the concrete and reduce the generation of cracks.

[0022] In a second aspect, the present application provides a method for preparing a large volume of anti-crack and anti-corrosion concrete for underground spaces using the following technical solution: A method for preparing crack-resistant and corrosion-resistant large-volume concrete for underground spaces comprises: uniformly mixing cement, fly ash, coarse aggregate, fine aggregate, carbon fiber and graphite particles to obtain a dry mixture; uniformly mixing the remaining raw materials, adding the dry mixture and fully mixing to obtain the crack-resistant and corrosion-resistant large-volume concrete for underground spaces.

[0023] In the above technical solution, the present application can ensure the uniform distribution of each raw material and improve the uniformity and performance stability of concrete by first mixing cement, fly ash, coarse aggregate, fine aggregate, carbon fiber and graphite particles uniformly, and then adding and mixing the remaining raw materials uniformly. At the same time, the preparation method is simple and easy to implement and is suitable for large-scale production.

[0024] On the third aspect, the present application also provides an application of large-volume concrete that is resistant to cracking and corrosion in underground spaces. The large-volume concrete of the present application can be widely used in underground space projects such as underground stations, tunnels, and basements to improve the project's crack resistance and erosion resistance and extend the project's service life.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. This application introduces carbon fiber and graphite particles into large-volume concrete. The two complement each other to construct a three-dimensional heat conduction network inside the concrete, accelerate the conduction and dissipation of heat, significantly reduce the temperature gradient inside and outside the large-volume concrete, and reduce the risk of cracks caused by temperature differences.

[0026] 2. This application introduces polyethylene glycol distearate, diethanol monoisopropanolamine and D-mannitol as anti-seepage agents for large-volume concrete, which can synergistically refine the pore structure of concrete, block internal pore channels, and significantly improve the density, anti-seepage and durability of concrete, thereby effectively controlling crack generation and improving the crack resistance, erosion resistance and mechanical properties of large-volume concrete.

[0027] 3. This application introduces modified cellulose fibers and utilizes the water retention and network structure of sodium polyacrylate to enhance the interfacial bonding between the fibers and the concrete matrix, thereby further improving the crack resistance of the concrete.

[0028] 4. This application improves the density and workability of concrete, and further enhances the crack resistance and erosion resistance of concrete by controlling the particle size and ratio of fine aggregate and coarse aggregate, as well as the particle size of graphite particles and the mass ratio of carbon fiber to graphite particles. DETAILED DESCRIPTION

[0029] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0030] Example 1 A crack-resistant and corrosion-resistant large-volume concrete for underground spaces includes 328 kg of cement, 82 kg of fly ash, 1036 kg of coarse aggregate, 678 kg of fine aggregate, 13 kg of carbon fiber, 15 kg of graphite particles, 5.3 kg of impermeability agent, 2.8 kg of water reducing agent, 8 kg of modified cellulose fiber and 164 kg of water.

[0031] Among them, the cement is P.O42.5 ordinary Portland cement manufactured by Hunan Pingtang Southern Cement Co., Ltd.

[0032] Among them, the fly ash is the first-grade fly ash produced by Shijiazhuang Bennuo Mineral Products Co., Ltd.

[0033] Among them, the coarse aggregate is graded limestone crushed stone with a particle size between 5 and 37.5 mm.

[0034] Among them, fine aggregate is natural medium-coarse sand with a particle size between 0.35 and 0.5 mm.

[0035] Among them, the carbon fiber was purchased from Jiangxi Shuobang New Material Technology Co., Ltd. with a length of 10 to 15 mm and a diameter of 3 to 6 μm.

[0036] Among them, graphite particles were purchased from Hebei Ruitong Carbon Co., Ltd., with a particle size of 0.05 to 0.1 mm.

[0037] Wherein, the anti-seepage agent is a mixture of 3.2 kg of polyethylene glycol distearate, 1.4 kg of diethanol monoisopropanolamine and 1.7 kg of D-mannitol.

[0038] Among them, polyethylene glycol distearate was purchased from Hubei Fangde New Materials Co., Ltd., CAS number: 9005-08-7.

[0039] Among them, diethanol monoisopropanolamine was purchased from Boxuan Chemical (Shandong) Co., Ltd., model: industrial grade.

[0040] Among them, D-mannitol was purchased from Guangzhou Huayu Biotechnology Co., Ltd., model: industrial grade.

[0041] Among them, the water reducer is lignin sulfonate, which was purchased from Guangzhou Taili Chemical Co., Ltd. with the item number: sodium lignin.

[0042] The modified cellulose fiber is prepared by taking 10 kg of cellulose fiber, soaking it in 40 kg of 5%wt sodium polyacrylate solution for 12 minutes, and then taking it out and drying it to obtain the modified cellulose fiber.

[0043] The cellulose fibers were purchased from Taian Senyang Composite Materials Co., Ltd., with a length of 2 to 3 mm and a diameter of 15 to 20 μm.

[0044] Among them, the preparation method of large-volume concrete for underground space that is resistant to cracking and corrosion includes: mixing cement, fly ash, coarse aggregate, fine aggregate, carbon fiber, and graphite particles evenly to obtain a dry mixture; mixing the remaining raw materials evenly, adding the dry mixture, and mixing them thoroughly to obtain large-volume concrete for underground space that is resistant to cracking and corrosion.

[0045] Example 2 A crack-resistant and corrosion-resistant large-volume concrete for underground spaces, which is different from Example 1 in that it includes 320kg of cement, 76kg of fly ash, 1025kg of coarse aggregate, 670kg of fine aggregate, 15kg of carbon fiber, 14kg of graphite particles, 4kg of impermeability agent, 2kg of water reducer, 6kg of modified cellulose fiber and 155kg of water.

[0046] Wherein, the anti-osmosis agent is a mixture of 2kg of polyethylene glycol distearate, 1kg of diethanol monoisopropanolamine and 1kg of D-mannitol.

[0047] The modified cellulose fiber is prepared by taking 10 kg of cellulose fiber, soaking it in 50 kg of 5%wt sodium polyacrylate solution for 10 minutes, and then taking it out and drying it to obtain the modified cellulose fiber.

[0048] Among them, the preparation method of large-volume concrete for underground space that is resistant to cracking and corrosion includes: mixing cement, fly ash, coarse aggregate, fine aggregate, carbon fiber, and graphite particles evenly to obtain a dry mixture; mixing the remaining raw materials evenly, adding the dry mixture, and mixing them thoroughly to obtain large-volume concrete for underground space that is resistant to cracking and corrosion.

[0049] Example 3 A crack-resistant and corrosion-resistant large-volume concrete for underground spaces, which is different from Example 1 in that it includes 335kg of cement, 88kg of fly ash, 1050kg of coarse aggregate, 685kg of fine aggregate, 11kg of carbon fiber, 17kg of graphite particles, 6kg of impermeability agent, 3kg of water reducer, 9kg of modified cellulose fiber and 170kg of water.

[0050] Wherein, the anti-osmosis agent is a mixture of 4kg of polyethylene glycol distearate, 2kg of diethanol monoisopropanolamine and 2kg of D-mannitol.

[0051] The modified cellulose fiber is prepared by taking 10 kg of cellulose fiber, soaking it in 45 kg of 5%wt sodium polyacrylate solution for 15 minutes, and then taking it out and drying it to obtain the modified cellulose fiber.

[0052] Among them, the preparation method of large-volume concrete for underground space that is resistant to cracking and corrosion includes: mixing cement, fly ash, coarse aggregate, fine aggregate, carbon fiber, and graphite particles evenly to obtain a dry mixture; mixing the remaining raw materials evenly, adding the dry mixture, and mixing them thoroughly to obtain large-volume concrete for underground space that is resistant to cracking and corrosion.

[0053] Example 4 A large-volume concrete for underground space that is crack-resistant and corrosion-resistant. The difference from Example 1 is that the coarse aggregate is composed of fine limestone crushed stone with a particle size between 5 and 17.5 mm and coarse limestone crushed stone with a particle size between 21.5 and 37.5 mm in a mass ratio of 1:1.

[0054] Example 5 A crack-resistant and corrosion-resistant large-volume concrete for underground spaces, which is different from Example 1 in that the modified cellulose fibers are replaced by cellulose fibers in equal amounts.

[0055] Example 6 A crack-resistant and corrosion-resistant large-volume concrete for underground spaces, which is different from Example 1 in that it does not contain modified cellulose fibers.

[0056] Comparative Example 1 A large volume of crack-resistant and corrosion-resistant concrete for underground spaces, which is different from Example 1 in that it does not contain carbon fiber.

[0057] Comparative Example 2 A large volume of crack-resistant and corrosion-resistant concrete for underground spaces, which is different from Example 1 in that it does not contain graphite particles.

[0058] Comparative Example 3 A large volume of crack-resistant and corrosion-resistant concrete for underground spaces, which is different from Example 1 in that it does not contain an anti-seepage agent.

[0059] Comparative Example 4 A large volume of crack-resistant and corrosion-resistant concrete for underground spaces. The difference from Example 1 is that polyethylene glycol distearate is not added to the anti-seepage agent.

[0060] Comparative Example 5 A large volume of crack-resistant and corrosion-resistant concrete for underground spaces. The difference from Example 1 is that diethanol monoisopropanolamine is not added to the anti-seepage agent.

[0061] Comparative Example 6 A large volume of crack-resistant and corrosion-resistant concrete for underground spaces. The difference from Example 1 is that D-mannitol is not added to the anti-seepage agent.

[0062] Performance testing mechanical properties: Prepare standard concrete test blocks in accordance with GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete", and conduct 28d compressive strength test on the concrete test blocks.

[0063] Setting time: Determine the initial and final setting time of concrete by the penetration resistance method in accordance with GB / T 50080-2016 "Standard for test methods for properties of ordinary concrete mixtures".

[0064] Early crack resistance: Prepare standard concrete test blocks with reference to GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete", and measure the total crack area per unit area 24 hours after concrete pouring.

[0065] Corrosion resistance: Refer to the fast chloride ion migration coefficient method in GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" to detect the depth of chloride ion penetration.

[0066] The above test results are shown in Table 1.

[0067] Table 1: Combining Examples 1-6, Comparative Examples 1-6 and Table 1, it is not difficult to see that the mass concrete of Examples 1-6 has good crack resistance, erosion resistance and mechanical properties.

[0068] Combined with the analysis of Example 1 and Comparative Examples 1-2, it is not difficult to see that the simultaneous introduction of carbon fiber and graphite particles into large-volume concrete can better alleviate the crack problem caused by temperature difference during the hydration process of concrete, thereby reducing the area of ​​cracks generated in the early stage of concrete, thereby improving the crack resistance, erosion resistance and mechanical properties of concrete.

[0069] Combined with the analysis of Example 1 and Comparative Examples 3-6, it is not difficult to see that the anti-seepage agent formed by the compounding of polyethylene glycol distearate, diethanol monoisopropanolamine and D-mannitol can not only synergistically refine the pore structure of concrete, block the internal pore channels, and significantly improve the density of concrete, but also such an anti-seepage agent can delay the setting time of concrete, further reduce the internal and external temperature gradient during the setting process of concrete, and further reduce the cracks generated in the early stage of concrete, thereby significantly improving the crack resistance, erosion resistance and mechanical properties of large-volume concrete.

[0070] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. A large volume concrete for underground space that is resistant to cracking and corrosion, characterized in that: The mass concrete comprises 320-335 parts of cement, 76-88 parts of fly ash, 1025-1050 parts of coarse aggregate, 670-685 parts of fine aggregate, 11-15 parts of carbon fiber, 14-17 parts of graphite particles, 4-6 parts of anti-seepage agent, 2-3 parts of water reducing agent and 155-170 parts of water; the anti-seepage agent is a mixture of polyethylene glycol distearate, diethanol monoisopropanolamine and D-mannitol in a mass ratio of (2-4):(1-2):(1-2).

2. The underground space anti-cracking and anti-corrosion mass concrete according to claim 1, characterized in that: Calculated by the mass fraction of the mass concrete, 6 to 9 parts of modified cellulose fibers are further added to the mass concrete, and the modified cellulose fibers are prepared by soaking cellulose fibers in a sodium polyacrylate solution and then drying them.

3. The underground space crack-resistant mass concrete according to claim 2, characterized in that: The preparation method of the modified cellulose fiber comprises: taking cellulose fiber, soaking it in a 5%wt sodium polyacrylate solution for 10-15 minutes, then taking it out and drying it to obtain the modified cellulose fiber; the mass ratio of the cellulose fiber to the 5%wt sodium polyacrylate solution is 1:(4-5).

4. The underground space crack-resistant and corrosion-resistant large-volume concrete according to claim 1, characterized in that: The water reducing agent is lignin sulfonate.

5. The underground space crack-resistant and corrosion-resistant large-volume concrete according to claim 1, characterized in that: The particle size of the fine aggregate is between 0.35 and 0.5 mm, and the coarse aggregate is composed of fine crushed stone with a particle size between 5 and 17.5 mm and coarse crushed stone with a particle size between 21.5 and 37.5 mm. The mass ratio of the fine crushed stone to the coarse crushed stone is 1:

1.

6. The underground space anti-cracking and anti-corrosion mass concrete according to claim 1, characterized in that: The particle size of the graphite particles is between 0.05 and 0.1 mm.

7. The underground space anti-cracking and anti-corrosion mass concrete according to claim 6, characterized in that: The mass ratio of the carbon fiber to the graphite particles is (13-15): (14-15).

8. A method for preparing the underground space anti-cracking and anti-corrosion mass concrete according to any one of claims 1 to 7, characterized in that: include: Mix cement, fly ash, coarse aggregate, fine aggregate, carbon fiber and graphite particles uniformly to obtain a dry mix; The remaining raw materials are mixed evenly, and then the dry mix is ​​added and mixed thoroughly to obtain a large volume of underground space resistant to cracking and corrosion.

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