A kind of anti-cracking thermal insulation concrete material for subway stations and its preparation method

Abstract

The present invention discloses a subway station anti-cracking and thermal insulation concrete material and a preparation method thereof, and belongs to the technical field of concrete materials. The preparation method provided by the present invention comprises the following steps: shield slag, expanded quartz and expanded vermiculite are dried and crushed, and then stirred and evenly mixed in a mass ratio of (8-12): (0.8-1.2): (0.8-1.2), and then water is added to mix and then granulated to obtain raw material balls; the raw material balls are dried, preheated and then calcined to obtain porous ceramsite; the porous ceramsite, cement, fine sand, silica fume and fly ash are mixed evenly, and a water-reducing agent aqueous solution is added. After stirring, the foamed protein-based foaming agent aqueous solution is added, and the foamed protein-based foaming agent aqueous solution is added, and the foamed protein-based foaming agent aqueous solution is stirred again to obtain. The above-mentioned method of the present invention can realize the large-scale disposal of shield slag solid waste, the production process is simple and low-cost, and it is easy to be applied on a large scale. Moreover, the prepared concrete material has good anti-cracking and thermal insulation properties.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete materials, and in particular to a crack-resistant and heat-insulating concrete material for a subway station and a preparation method thereof. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] In the construction of large-scale infrastructure such as subway stations, the integrity and stability of concrete structures are crucial for ensuring their safe operation. Cracks are a common problem in concrete structures within subway stations, which not only directly impacts their durability and safety but can also lead to water seepage, further accelerating structural corrosion and increasing maintenance costs. Furthermore, subway stations, being deeply buried underground, experience rapid temperature loss, often requiring significant amounts of electrical energy to maintain temperature. Therefore, a new material that can reduce concrete cracking while also providing thermal insulation is crucial.

[0004] Currently, various methods exist to reduce concrete cracking, including but not limited to the use of admixtures, adjusting concrete mix proportions, and introducing fiber materials. While these methods each have their advantages and disadvantages, they all suffer from high costs, complex construction, or impairment of concrete properties. In particular, traditional solutions for thermal insulation often require additional insulation layers, which not only increases the weight of the structure but also complicates the construction process.

[0005] Therefore, how to provide a subway station anti-cracking and thermal insulation concrete material with low cost, simple construction and good anti-cracking and thermal insulation effects is an urgent problem to be solved. Summary of the Invention

[0006] In view of this, the present invention provides a crack-resistant and thermal insulation concrete material for subway stations and a preparation method thereof, which solves the problems of high cost, complex construction and large dead weight of existing crack-resistant and thermal insulation materials. In addition, the present invention can achieve large-scale disposal of shield slag and solid waste, showing significant environmental and economic benefits.

[0007] In a first aspect, the present invention provides a method for preparing a crack-resistant and thermal-insulating concrete material for a subway station, comprising the following steps:

[0008] Shield slag, expanded quartz and expanded vermiculite are dried and crushed, and then stirred and mixed in a mass ratio of (8-12): (0.8-1.2): (0.8-1.2), and then water is added to mix and granulate to obtain raw balls; the raw balls are dried, preheated and calcined to obtain porous ceramsite;

[0009] The porous ceramsite, cement, fine sand, silica fume and fly ash are mixed evenly, and a water reducer aqueous solution is added. After stirring, the foamed protein-based foaming agent aqueous solution is added and stirred evenly again to obtain the product.

[0010] Preferably, the SiO2 content in the shield slag is 70-73%, and the Al2O3 content is 11.5-13%.

[0011] Preferably, the density of the expanded quartz is lower than 2.5 g / cm 3 , the compressive strength is above 20MPa.

[0012] Preferably, the density of the expanded vermiculite is lower than 1.6 g / cm 3 , the expansion coefficient is 0.15~0.2.

[0013] Preferably, the particle size of the dried and crushed shield slag, expanded quartz and expanded vermiculite is below 75 μm.

[0014] Preferably, in the step of granulating after adding water and mixing evenly, the amount of water added is 10 to 15 wt % of the total mass of the dried and crushed shield slag, expanded quartz powder and expanded vermiculite powder.

[0015] Preferably, in the step of drying and preheating the raw balls and then calcining them, the drying temperature is 80-120° C. and the drying time is 5-20 h; the preheating temperature is 500-800° C. and the preheating time is 0.4-1 h.

[0016] Preferably, in the step of calcining the raw balls after drying and preheating, the calcination temperature is 1000-1500° C. and the calcination time is 0.4-1 h.

[0017] Preferably, the mass ratio of the porous ceramsite, cement, fine sand, silica fume, fly ash, water reducer and protein-based foaming agent is (50-60):(300-320):(440-460):(55-65):(55-65):(3-6):(1-2); the concentration of the water reducer aqueous solution is 2-3wt%; the concentration of the protein-based foaming agent aqueous solution is 2-5wt%.

[0018] Preferably, the cement is ordinary Portland cement, with a grade not lower than PO42.5.

[0019] Preferably, the water reducer is a polycarboxylic acid-based high-efficiency water reducer with a water reduction rate of more than 30%.

[0020] Preferably, the fine sand is 180-220 mesh quartz sand with a bulk density of less than 1500 kg / m 3 .

[0021] Preferably, the fly ash is of grade I, with a loss on ignition of less than 2.0% and a specific surface area of ​​1100 cm 2 / g or above.

[0022] Preferably, the mass percentage of silicon dioxide in the silica fume is above 97%, and the specific surface area is 20 to 25 m 2 / g, density is 2.1~2.3g / cm 3 .

[0023] Preferably, the protein-based foaming agent has a water content of less than 6.0 wt%, an insoluble solid content of less than 0.5 wt%, a pH value of 5 to 7, and an initial foam volume of 150 to 200 mL.

[0024] Preferably, in the step of uniformly mixing the porous ceramsite, cement, fine sand, silica fume and fly ash, the mixing time is 3 to 5 minutes and the mixing speed is 50 to 80 r / min.

[0025] Preferably, the stirring speed after adding the water reducer aqueous solution is 100-150 r / min, and the stirring time is 3-5 min; the stirring speed after adding the foamed protein-based foaming agent aqueous solution is 100-150 r / min, and the stirring time is 3-5 min.

[0026] In a second aspect, the present invention provides a crack-resistant and thermal-insulating concrete material for subway stations prepared by the above-mentioned preparation method.

[0027] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0028] (1) The present invention uses shield slag waste as the main raw material to prepare porous ceramsite, and directly forms porous ceramsite with thermal insulation function through crushing, mixing, granulation and calcination. The porous ceramsite is used as one of the raw materials for anti-cracking thermal insulation materials, which not only solves the problem of solid waste disposal, reduces environmental pollution, but also reduces material costs; the production process is simple and easy to apply on a large scale;

[0029] (2) The introduction of expanded quartz and expanded vermiculite into the porous ceramsite of the present invention reduces the density of the porous ceramsite, reduces its deadweight, and can improve the application safety of the concrete material. At the same time, it also improves the strength, chemical stability and durability of the porous ceramsite. The shield slag waste-based porous ceramsite can exert good water absorption and release properties in the concrete material, effectively maintain the concrete, and reduce the cracking problem.

[0030] (3) The anti-cracking and thermal insulation concrete material for subway stations of the present invention contains porous expanded vermiculite and expanded quartz combined with a protein-based foaming agent, so that the obtained concrete material has good thermal insulation performance, effectively reduces heat energy transfer, and can reduce energy consumption when used in subway stations, showing significant economic benefits. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0032] The present invention provides a method for preparing a crack-resistant and thermal-insulating concrete material for a subway station, comprising the following steps:

[0033] Shield slag, expanded quartz and expanded vermiculite are dried and crushed, and then stirred and mixed in a mass ratio of (8-12): (0.8-1.2): (0.8-1.2), and then water is added to mix and granulate to obtain raw balls; the raw balls are dried, preheated and calcined to obtain porous ceramsite;

[0034] The porous ceramsite, cement, fine sand, silica fume and fly ash are mixed evenly, and a water reducer aqueous solution is added. After stirring, the foamed protein-based foaming agent aqueous solution is added and stirred evenly again to obtain the product.

[0035] The present invention first prepares porous ceramsite based on shield slag, and then adds cement, a foaming agent, and auxiliary mineral materials to form a concrete material. The porous ceramsite has a porous structure, which enables it to absorb and release water, providing maintenance for the concrete and reducing cracking problems in the concrete material. However, the inventors discovered that porous ceramsite prepared directly from shield slag suffers from low strength, poor pore structure, and low thermal insulation capacity. To address these issues, the present invention adds appropriate amounts of expanded quartz and expanded vermiculite during the preparation process of the porous ceramsite.

[0036] Expanded quartz has a lower density and higher strength, helping to reduce the material's weight and lower structural loads. Expanded vermiculite has superior expansion properties and continues to expand slightly at high temperatures, resulting in a more uniform particle size distribution than expanded quartz, which can help improve the material's pore structure. When added to the porous ceramsite raw materials in powder form, since they have already expanded, they do not undergo significant volume changes during the preparation process, preventing surface cracking and resulting strength loss. However, during high-temperature calcination, their presence promotes micro-expansion of the ceramsite, improving its pore structure and overall mechanical properties. This, in turn, reduces the weight of the ceramsite, enhancing both the thermal insulation performance and safety of the concrete. Furthermore, since both expanded quartz and vermiculite are stable minerals, their combination can improve the chemical stability and durability of the porous ceramsite, extending its service life.

[0037] If the addition amount of expanded quartz and expanded vermiculite is too low, the performance of porous ceramsite and concrete materials will not be greatly improved; if the addition amount of expanded quartz and expanded vermiculite is too high, the surface of porous ceramsite will be cracked and the pore structure will be destroyed, affecting the working performance and compressive strength.

[0038] The present invention also discovered that when porous ceramsite and a protein-based foaming agent are added simultaneously during the preparation of a concrete material, a concrete material with excellent thermal insulation properties can be obtained. The protein-based foaming agent must be foamed before being added to the other raw materials to form a uniform pore structure in the material, thereby effectively reducing the density of the material, reducing the deadweight of the material, improving the material's construction performance and interfacial bonding strength, and enhancing the material's thermal insulation properties and thermal insulation effect. The present invention does not impose any particular restrictions on the foaming process of the protein-based foaming agent, and foaming methods familiar to those skilled in the art can be used. For example, an aqueous solution of the protein-based foaming agent is added to a foaming machine for foaming.

[0039] Through the above technical solution, the present invention can not only dispose of a large amount of shield slag and relieve environmental pressure, but also realize the high-value utilization of shield slag, with good environmental and economic benefits.

[0040] In the shield slag of the present invention, the SiO2 content is 70-73wt%, and the Al2O3 content is 11.5-13wt%.

[0041] In the present invention, the density of the expanded quartz is lower than 2.5g / cm 3 , the compressive strength is above 20MPa.

[0042] In the present invention, the density of the expanded vermiculite is lower than 1.6 g / cm 3 , the expansion coefficient is 0.15~0.2.

[0043] In the present invention, the particle size of the shield excavation soil, expanded quartz, and expanded vermiculite after drying and pulverization is below 75 μm. The present invention imposes no particular restrictions on the drying and pulverization process; commonly used drying and pulverization methods in the art can be employed. This drying and pulverization process allows for more uniform mixing of the shield excavation soil, expanded quartz, and expanded vermiculite, facilitating the subsequent calcination process.

[0044] In the step of adding water and mixing thoroughly before granulation, the amount of water added is 10-15 wt% of the total mass of the dried and crushed shield slag, expanded quartz powder and expanded vermiculite powder. The addition of an appropriate amount of water is conducive to forming a good bond between the materials, thereby facilitating granulation.

[0045] In the present invention, the raw balls are dried and preheated before calcining at a temperature of 80-120°C for 5-20 hours. Drying is performed to evaporate moisture. The preheating temperature is 500-800°C, more preferably 600-700°C, and the preheating time is 0.4-1 hour, more preferably 0.4-0.6 hour. The primary purpose of the preheating process is to gradually heat the raw balls to a certain temperature before entering the high-temperature calcination stage, ensuring sufficient calcination and expansion within the balls. Preheating removes volatile substances and moisture from the raw balls, preventing them from suddenly expanding and bursting at high temperatures. The calcination temperature is 1000-1500°C, more preferably 1200-1300°C, and the calcination time is 0.4-1 hour, more preferably 0.4-0.6 hour. During the calcination process, the organic and inorganic substances in the raw material balls will undergo chemical changes and carbonize into the main components of the ceramsite, forming the required porous structure. At the same time, the expanded vermiculite plays a micro-expansion role, causing the ceramsite to expand slightly, improving the pore structure and enhancing the overall performance.

[0046] In the present invention, the mass ratio of the porous ceramsite, cement, fine sand, silica fume, fly ash, water reducer, and protein-based foaming agent is (50-60):(300-320):(440-460):(55-65):(55-65):(3-6):(1-2); the concentration of the water reducer aqueous solution is 2-3wt%; the concentration of the protein-based foaming agent aqueous solution is 2-5wt%, more preferably 3-4wt%. With the above ratio, a concrete material with good crack resistance and thermal insulation properties can be prepared.

[0047] The porous ceramsite prepared by the invention has a particle size of 5 to 10 mm and is used as a part of lightweight aggregate in concrete materials.

[0048] In the present invention, the cement is ordinary Portland cement, with a grade of not less than PO42.5. The water reducer is a polycarboxylic acid-based high-efficiency water reducer, with a water reduction rate of more than 30%. Ordinary Portland cement and the polycarboxylic acid-based high-efficiency water reducer have good compatibility, and ordinary Portland cement is used as the primary cementitious material.

[0049] In the present invention, the fine sand is 180-220 mesh quartz sand with a bulk density of less than 1500 kg / m 3 , which acts as a filler in concrete, filling the gaps between aggregates and making the concrete material dense.

[0050] In the present invention, the fly ash is of grade I, with a loss on ignition of less than 2.0% and a specific surface area of ​​1100 cm 2 / g or more. Fly ash as an auxiliary cementitious material can improve the anti-permeability performance of concrete materials. The mass percentage of silicon dioxide in the silica ash is more than 97%, and the specific surface area is 20 to 25m 2 / g, density is 2.1~2.3g / cm 3 As a mineral admixture, silica fume can fill voids and improve the density of concrete materials.

[0051] The preferred protein-based foaming agent of the present invention has a water content of less than 6.0 wt%, a solid insoluble content of less than 0.5 wt%, a pH of 5 to 7, and an initial foam volume of 150 to 200 mL. The present invention does not impose any particular restrictions on the type of protein-based foaming agent; plant protein-based foaming agents or animal protein-based foaming agents can be used, with animal protein-based foaming agents being preferred, as they have advantages such as high foaming multiples, high strength, good stability, and low cost.

[0052] In the present invention, in the step of uniformly mixing the porous ceramsite, cement, fine sand, silica fume, and fly ash, the mixing time is 3 to 5 minutes and the mixing speed is 50 to 80 r / min. After adding the water reducer aqueous solution, the stirring speed is 100 to 150 r / min and the stirring time is 3 to 5 minutes; after adding the foamed protein-based foaming agent aqueous solution, the stirring speed is 100 to 150 r / min and the stirring time is 3 to 5 minutes.

[0053] The present invention also provides a crack-resistant and thermal-insulating concrete material for subway stations prepared by the above-mentioned preparation method. The crack-resistant and thermal-insulating concrete material for subway stations provided by the present invention has excellent crack resistance, thermal insulation, and anti-permeability properties, a thermal conductivity coefficient of less than 2.0 W / (m·K), and an anti-permeability grade greater than 12.

[0054] The technical solution of the present invention will be further described below in conjunction with specific embodiments. Unless otherwise specified, the following parts are all parts by mass.

[0055] In the following embodiments:

[0056] The SiO2 content in shield tunneling slag is 70.2wt% and the Al2O3 content is 12.4wt%.

[0057] The density of expanded quartz is 1.6g / cm3 , the compressive strength is 24MPa.

[0058] The density of expanded vermiculite is 2.0g / cm 3 , the expansion coefficient is 18%.

[0059] The cement is ordinary Portland cement with a grade of PO42.5.

[0060] The water reducer is a polycarboxylic acid-based high-efficiency water reducer with a solid content of 20%, a pH value of about 7.5, and a water reduction rate of more than 30%.

[0061] The protein-based foaming agent is an animal protein-based foaming agent, with a moisture content of less than 6.0%, a solid insoluble matter of less than 0.5%, a pH value of 6, and an initial foam volume of 170 mL.

[0062] The fine sand is 200 mesh quartz sand with a bulk density of 1400 kg / m 3 .

[0063] The fly ash is Grade I, with a loss on ignition of less than 2.0% and a specific surface area greater than 1100 cm 2 / g.

[0064] The mass percentage of silicon dioxide in the silica ash is 97.6%, and the specific surface area is 1150m 2 / g, density is 2.20g / cm 3 .

[0065] Example 1

[0066] This embodiment provides a crack-resistant and thermal-insulating concrete material for a subway station and a preparation method thereof.

[0067] (1) Preparation of porous ceramsite for shield slag base:

[0068] After the shield slag, expanded quartz, and expanded vermiculite are naturally air-dried, they are placed in an oven and dried for 24 hours. After drying, they are crushed separately using a ball mill. After crushing, they are sieved and the sieve size is 200 mesh. 200 parts of the crushed and sieved shield slag, 20 parts of expanded quartz, and 20 parts of expanded vermiculite are poured into a blender and stirred for 10 minutes to obtain a mixture. 12.5wt% of water is added to the mixture and mixed thoroughly. The mixture is granulated into balls in a granulator. The raw balls are sieved with a 4.75mm sieve and then placed in a 105℃ oven to dry for 12 hours. The dried raw balls are placed in a resistance furnace and preheated at 600℃ for 0.5 hours to initially form carbonized ceramsite. After preheating, the temperature is adjusted to 1200℃ and calcined for 0.5 hours. After calcination, the balls are naturally cooled at room temperature to form shield slag-based porous ceramsite with a particle size of 5 to 8mm.

[0069] (2) Preparation of anti-cracking and thermal insulation concrete materials for subway stations:

[0070] In this embodiment, the anti-cracking and thermal insulation concrete material for the subway station includes the following raw materials in parts by mass: 300 parts of cement, 50 parts of shield slag-based porous ceramsite, 55 parts of silica fume, 55 parts of fly ash, 1 part of protein-based foaming agent, 450 parts of fine sand, 4.5 parts of polycarboxylic acid high-efficiency water reducer, and 230 parts of water.

[0071] According to the above proportions, cement, porous ceramsite, fine sand, silica fume and fly ash are uniformly stirred at a stirring rate of 60 r / min for 4 minutes. After uniform mixing, an aqueous solution of a polycarboxylic acid high-efficiency water reducer (4.5 parts of water reducer + 200 parts of water) is added and stirred at a stirring rate of 120 r / min for 4 minutes. After 1 part of a protein-based foaming agent and 30 parts of water are mixed to form a protein-based foaming agent aqueous solution, the protein-based foaming agent aqueous solution is poured into a foaming machine to produce foam, and the foam is added to the stirred cement-based material and stirred again at a stirring rate of 120 r / min for 4 minutes to obtain a crack-resistant and thermal insulation concrete material for subway stations.

[0072] Example 2

[0073] This Example differs from Example 1 in that: In this Example, 320 parts of cement, 60 parts of shield-mover-soil porous ceramsite, 60 parts of silica fume, 60 parts of fly ash, 1.5 parts of a protein-based foaming agent, 450 parts of fine sand, 4.5 parts of a polycarboxylate superplasticizer, and 230 parts of water are used. The aqueous solution of the polycarboxylate superplasticizer is 4.5 parts of the superplasticizer plus 185 parts of water. The protein-based foaming agent aqueous solution is formed by mixing 1 part of the protein-based foaming agent with 45 parts of water. The remaining steps are the same as in Example 1.

[0074] Example 3

[0075] Compared with Example 1, the present embodiment differs in that, in the preparation process of shield slag-based porous ceramsite in the present embodiment, the shield slag is 200 parts, the expanded quartz is 25 parts, and the expanded vermiculite is 25 parts.

[0076] Comparative Example 1

[0077] The difference between this comparative example and Example 1 is that in this comparative example, expanded quartz and expanded vermiculite are not added during the preparation of the shield slag-based porous ceramsite.

[0078] Comparative Example 2

[0079] Compared with Example 1, the difference between this comparative example and Example 1 is that in the preparation process of shield slag-based porous ceramsite in this comparative example, the shield slag is 200 parts, the expanded quartz is 40 parts, and the expanded vermiculite is 40 parts.

[0080] Comparative Example 3

[0081] Compared with Example 1, the difference between this comparative example and Example 1 is that: in the preparation process of the anti-cracking and thermal insulation concrete material for the subway station, the shield slag-based porous ceramsite is not added in this comparative example, and the missing part is supplemented by cement: 350 parts of cement, 55 parts of silica fume, 55 parts of fly ash, 1 part of protein-based foaming agent, 450 parts of fine sand, 4.5 parts of polycarboxylic acid high-efficiency water reducer, and 230 parts of water.

[0082] Comparative Example 4

[0083] The difference between this comparative example and Example 1 is that in this comparative example, no protein-based foaming agent is added during the preparation of the anti-cracking and thermal insulation concrete material for subway stations.

[0084] Test example

[0085] The properties of the concrete materials of Examples 1 to 3 and Comparative Examples 1 to 4 were measured, as shown in Table 1.

[0086] Table 1 Concrete material performance determination

[0087]

[0088] As can be seen from Table 1, the addition of porous ceramsite significantly improves the working performance and mechanical properties of the material, especially the material's crack resistance. The compressive strength of the concrete materials added with porous ceramsite shown in Examples 1 to 3 is greater than 24 MPa, which is higher than the 23.5 MPa of Comparative Example 3. In particular, the early shrinkage is controlled within 310 mm, which is much smaller than the 849 mm of Comparative Example 3. It can be found that the addition of porous ceramsite reduces cracks in the concrete material, increases the density of the structure, and improves the performance of the concrete material. Secondly, through Comparative Examples 1 and 2, it can be seen that the addition of expanded quartz and expanded vermiculite improves certain properties of porous ceramsite, but excessive addition will lead to a sharp decline in material properties. Therefore, it is necessary to reasonably control the amount of expanded quartz and expanded vermiculite added. Thirdly, through Comparative Example 4, it can be seen that protein-based foaming agents have a significant effect on the working performance and thermal insulation capacity of the material. The material of the embodiment of the present invention can be used as a crack-resistant and thermal insulation concrete material for subway stations, reducing energy consumption and achieving high-value utilization of shield slag waste.

[0089] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing crack-resistant thermal insulation concrete material for subway stations, characterized in that: The steps include: Shield slag, expanded quartz and expanded vermiculite are dried and crushed, and then stirred and mixed in a mass ratio of (8-12): (0.8-1.2): (0.8-1.2), and then water is added to mix and granulate to obtain raw balls; the raw balls are dried, preheated and calcined to obtain porous ceramsite; The porous ceramsite, cement, fine sand, silica fume and fly ash are mixed evenly, and a water reducer aqueous solution is added. After stirring, the foamed protein-based foaming agent aqueous solution is added and stirred evenly again to obtain the product.

2. The preparation method according to claim 1, wherein The shield slag has a SiO2 content of 70-73% and an Al2O3 content of 11.5-13%; the density of the expanded quartz is lower than 2.5 g / cm 3 , the compressive strength is above 20MPa; the density of the expanded vermiculite is lower than 1.6g / cm 3 , the expansion coefficient is 0.15~0.

2.

3. The preparation method according to claim 1, wherein The particle size of the dried and crushed shield slag, expanded quartz and expanded vermiculite is below 75 μm; in the step of adding water and mixing and then granulating, the amount of water added is 10-15wt% of the total mass of the dried and crushed shield slag, expanded quartz powder and expanded vermiculite powder.

4. The preparation method according to claim 1, wherein In the step of drying and preheating the raw material balls and then calcining them, the drying temperature is 80-120° C. and the drying time is 5-20 hours; the preheating temperature is 500-800° C. and the preheating time is 0.4-1 hour; and the calcining temperature is 1000-1500° C. and the calcining time is 0.4-1 hour.

5. The preparation method according to claim 1, wherein The mass ratio of the porous ceramsite, cement, fine sand, silica fume, fly ash, water reducer and protein-based foaming agent is (50-60):(300-320):(440-460):(55-65):(55-65):(3-6):(1-2); the concentration of the water reducer aqueous solution is 2-3wt%; the concentration of the protein-based foaming agent aqueous solution is 2-5wt%.

6. The preparation method according to claim 1, wherein The cement is ordinary Portland cement with a grade not lower than PO42.5; the water reducer is a polycarboxylic acid-based high-efficiency water reducer with a water reduction rate of more than 30%.

7. The preparation method according to claim 1, wherein The fine sand is 180-220 mesh quartz sand with a bulk density of less than 1500 kg / m 3 The fly ash is grade I, with a loss on ignition of less than 2.0% and a specific surface area of ​​1100cm 2 / g or more; the mass percentage of silicon dioxide in the silica ash is more than 97%, and the specific surface area is 20 to 25m 2 / g, density is 2.1~2.3g / cm 3 .

8. The preparation method according to claim 1, wherein The protein-based foaming agent has a water content of less than 6.0 wt%, a solid insoluble matter of less than 0.5 wt%, a pH value of 5-7, and an initial foam volume of 150-200 mL.

9. The preparation method according to claim 1, wherein In the step of uniformly mixing the porous ceramsite, cement, fine sand, silica fume and fly ash, the mixing time is 3 to 5 minutes and the mixing speed is 50 to 80 r / min; the stirring speed after adding the water reducer aqueous solution is 100 to 150 r / min and the stirring time is 3 to 5 minutes; the stirring speed after adding the foamed protein-based foaming agent aqueous solution is 100 to 150 r / min and the stirring time is 3 to 5 minutes.

10. The anti-cracking and thermal insulation concrete material for subway stations prepared by the preparation method according to any one of claims 1 to 9.

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