Method for preparing unfired ceramsite by taking coal gangue as raw material

Abstract

The invention belongs to the technical field of unfired ceramsite manufacturing, and particularly discloses a method for preparing unfired ceramsite by taking coal gangue as a raw material, which comprises the following steps: S1, drying coal gangue at 100-110 DEG C for 10-14 hours, ball-milling, and sieving with a 100-mesh sieve to obtain coal gangue powder; step S2, weighing all the materials; s3, uniformly mixing the coal gangue powder with cement, dihydrate gypsum and silica fume to obtain mixed powder; s4, adding anhydrous sodium carbonate into warm water, and uniformly mixing to obtain alkali liquor; s5, spraying alkali liquor into the mixed powder, granulating to obtain spherical particles, and screening, aging and curing the spherical particles; and step S6, drying or naturally drying the cured spherical particles in an environment at the temperature of 50-70 DEG C to obtain the unfired ceramsite. According to the method for preparing the non-sintered ceramsite by taking the coal gangue as the raw material, the problem of reutilization of the existing solid waste coal gangue can be solved, so that efficient reutilization of the coal gangue powder is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of unfired ceramsite production, and particularly relates to a method for preparing unfired ceramsite by taking coal gangue as raw material. Background Art

[0002] Coal gangue is a solid waste generated during coal mining and washing, with high carbon content, loose structure, and complex chemical composition. Due to its low strength, poor weathering resistance, and low chemical stability, the resource utilization of coal gangue has always faced challenges.

[0003] At present, open-air dumping is often used to dispose of coal gangue, which not only occupies a large amount of land and causes environmental pollution, but also may cause spontaneous combustion and leachate pollution, posing a potential threat to the ecosystem. Therefore, how to realize the resource reuse of coal gangue and turn it into treasure has become a technical problem that needs to be solved urgently.

[0004] Unburned ceramsite is an artificial aggregate formed by granulating and curing solid waste by adding cement and other cementitious materials. In order to solve the problem of recycling existing solid waste gangue, a method for preparing unburned ceramsite using gangue as raw material is needed in the art, which can effectively solve the above problem. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing unburned ceramsite using coal gangue as raw material, using solid waste coal gangue powder as the main raw material, cement as the main gelling material, anhydrous sodium carbonate, gypsum and silica fume as auxiliary gelling materials, and utilizing disc granulation to prepare unburned ceramsite that can be used in the construction industry, which can solve the problem of recycling of existing solid waste coal gangue, and thus realize the efficient recycling of coal gangue powder.

[0006] To achieve the above object, the present invention provides a method for preparing unburned ceramsite using coal gangue as raw material, comprising the following steps: Step S1, drying the gangue at 100-110° C. for 10-14 h, ball-milling the gangue, and passing the ball through a 100-mesh sieve to obtain gangue powder; Step S2, weighing each material; by weight, the amount of each material used is 60-70 parts of coal gangue powder, 20-23 parts of cement, 3-5 parts of silica fume, 2-4 parts of dihydrate gypsum; 4-6 parts of anhydrous sodium carbonate, and 25 parts of warm water; Step S3, mixing the coal gangue powder with cement, dihydrate gypsum and silica fume to obtain a mixed powder; Step S4, adding anhydrous sodium carbonate into warm water and mixing evenly to obtain alkali solution; Step S5, spraying the obtained alkali solution into the mixed powder in step S3, granulating, screening, aging and curing the spherical particles; Step S6, placing the cured spherical particles in an environment with a temperature of 50-70° C. for drying or natural drying to obtain unfired ceramsite.

[0007] Preferably, in step S2, the mass ratio of coal gangue powder to cement is 3:1.

[0008] Preferably, in step S2, the mass proportions of the main chemical components contained in the coal gangue powder are: SiO2 50%-55%, Al2O3 30%-35%, and Fe2O3 2%-5%.

[0009] Preferably, in step S2, the cement is 42.5 grade standard cement; the silica fume fineness is 2000 mesh, the SiO2 content in the silica fume is greater than 95%; and the sodium carbonate content in the anhydrous sodium carbonate is ≥99.8%.

[0010] Preferably, the granulation in step S5 is specifically as follows: a layer of engine oil is evenly applied on the inner wall of the disc of the disc granulator, the mixed powder is poured into the disc granulator, the alkali solution is slowly sprayed, and granulation is performed in the disc granulator; during the granulation process, the inclination angle of the disc granulator is 40-44°, and the rotation speed is 36-40r / min.

[0011] Preferably, in step S5, the particle size of the spherical particles after screening is 5-10 mm; the water absorption rate of the spherical particles after screening is 9-17% in 1 hour, the single particle strength is 2-4 MPa, and the bulk density is 900-1000 kg·m -3 .

[0012] Preferably, the aging in step S5 is specifically aging for 1 day in an environment with an air humidity of 50-70% and a temperature of 18-22°C.

[0013] Preferably, the curing method in step S5 is specifically steam curing and natural curing; the temperature of steam curing is 65°C-75°C, and the curing time is 24h; the temperature of natural curing is 18-22°C, and the curing time is 7d.

[0014] The present invention adopts the above method for preparing unburned ceramsite using coal gangue as raw material, and the beneficial effects are as follows: (1) The present invention uses coal gangue as the main raw material, which accounts for up to 70% of the unburned ceramsite, and can absorb a large amount of solid waste, realize the recycling of solid waste resources, increase the added value of resources, and solve the environmental resource problems caused by the large-scale storage of coal gangue; (2) The present invention uses coal gangue as the main raw material and does not require calcination of the coal gangue; (3) The present invention adopts a disc granulator to prepare unburned ceramsite that can be used in the construction industry. The raw materials are squeezed and cut by a rotating disc to form particles. The inclination angle and rotation speed are controlled to form spherical particles with a suitable particle size. (4) The preparation method of the present invention is simple and easy to implement, and has extremely low cost, is suitable for large-scale production, has good application prospects, and is suitable for popularization and application.

[0015] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The sample morphology of the unfired ceramsite prepared in Example 1 of the method for preparing unfired ceramsite using coal gangue as raw material of the present invention; Figure 2 The X-ray diffraction spectrum of the coal gangue powder used in Example 1 of the method for preparing unburned ceramsite using coal gangue as raw material of the present invention; Figure 3 The present invention discloses an X-ray diffraction spectrum of the unfired ceramsite prepared in Example 1 of a method for preparing unfired ceramsite using coal gangue as raw material. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0018] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0019] A method for preparing unburned ceramsite using coal gangue as raw material comprises the following steps: Step S1, drying the coal gangue at 100-110° C. for 10-14 h, ball-milling the coal gangue, and passing the mixture through a 100-mesh sieve to obtain coal gangue powder.

[0020] Step S2, weighing each material. In terms of weight, the amount of each material used is 60-70 parts of coal gangue powder, 20-23 parts of cement, 3-5 parts of silica fume, 2-4 parts of dihydrate gypsum, 4-6 parts of anhydrous sodium carbonate, and 25 parts of warm water. The mass ratio of coal gangue powder to cement is 3:1.

[0021] The main chemical components in the coal gangue powder are as follows: SiO2 50%-55%, Al2O3 30%-35%, Fe2O3 2%-5%. The cement is 42.5 grade standard cement. The fineness of silica fume is 2000 mesh, and the content of SiO2 in silica fume is greater than 95%. The content of sodium carbonate in anhydrous sodium carbonate is ≥99.8%.

[0022] Step S3, uniformly mixing the coal gangue powder with cement, dihydrate gypsum and silica fume to obtain a mixed powder.

[0023] Step S4: adding anhydrous sodium carbonate into warm water and mixing evenly to obtain alkaline solution.

[0024] Step S5, spraying the obtained alkali solution into the mixed powder in step S3, granulating, screening, aging and curing the spherical particles.

[0025] Specifically, the granulation process includes evenly applying a layer of machine oil on the inner wall of the disc of the disc granulator to prevent the material from adhering, pouring the mixed powder into the disc granulator, slowly spraying the alkali solution, and granulating the spherical particles in the disc granulator. During the granulation process, the inclination angle of the disc granulator is 40-44°, and the rotation speed is 36-40r / min.

[0026] The particle size of the spherical particles after screening is 5-10mm. The water absorption rate of the spherical particles after screening is 9-17% in 1h, the single particle strength is 2-4MPa, and the bulk density is 900-1000kg·m -3 .

[0027] The aging process is specifically to age the product in an environment with an air humidity of 50-70% and a temperature of 18-22°C for 1 day.

[0028] The specific curing methods are steam curing and natural curing. The temperature of steam curing is 65℃-75℃, and the curing time is 24h. The temperature of natural curing is 18-22℃, and the curing time is 7d.

[0029] Step S6, placing the cured spherical particles in an environment with a temperature of 50-70° C. for drying or natural drying to obtain unfired ceramsite.

[0030] Embodiment 1 A method for preparing unburned ceramsite using coal gangue as raw material comprises the following steps: Step S1, drying the coal gangue at 105° C. for 12 h, ball-milling the coal gangue, and passing the mixture through a 100-mesh sieve to obtain coal gangue powder.

[0031] Step S2, weighing each material. In terms of weight, the amount of each material used is 65 parts of coal gangue powder, 21 parts of cement, 5 parts of silica fume, 3 parts of dihydrate gypsum, 6 parts of anhydrous sodium carbonate, and 25 parts of warm water.

[0032] Step S3, uniformly mixing the coal gangue powder with cement, dihydrate gypsum and silica fume to obtain a mixed powder.

[0033] Step S4: adding anhydrous sodium carbonate into warm water and mixing evenly to obtain alkaline solution.

[0034] Step S5, evenly apply a layer of machine oil on the inner wall of the disc of the disc granulator to prevent material adhesion, pour the mixed powder into the disc granulator, slowly spray alkali solution, and granulate in the disc granulator to obtain spherical particles. During the granulation process, the inclination angle of the disc granulator is 42°, the rotation speed is 38r / min, and spherical particles of 10mm are formed.

[0035] The spherical particles were placed in an environment with an air humidity of 60% and a temperature of 20° C. for aging for 1 day.

[0036] The aged spherical particles were placed in a 70°C rapid steam curing box for 24 hours and naturally cured at 20°C for 7 days.

[0037] Step S6, placing the cured spherical particles in an environment with a temperature of 50° C. for drying to obtain unfired ceramsite.

[0038] like Figure 1 As shown in FIG. 1 , the appearance and internal morphology of the unfired ceramsite prepared in this embodiment. Figure 2 As shown, the coal gangue powder used in this embodiment belongs to inorganic silicate minerals, and its main components are quartz and kaolinite.

[0039] like Figure 3 As shown, the composition of the unfired ceramsite prepared in this embodiment is relatively complex, but the diffraction peaks of quartz and kaolinite, which are the basic components of stone powder, still exist. At the same time, substances such as CSH, CaCO3, and calcium aluminate produced by the hydration of cementitious materials such as cement are the main sources of the strength of the unfired ceramsite.

[0040] Embodiment 2 A method for preparing unburned ceramsite using coal gangue as raw material comprises the following steps: Step S1, drying the coal gangue at 105° C. for 12 h, ball-milling the coal gangue, and passing the mixture through a 100-mesh sieve to obtain coal gangue powder.

[0041] Step S2, weighing each material. In terms of weight, the amount of each material used is 65 parts of coal gangue powder, 21 parts of cement, 5 parts of silica fume, 2 parts of dihydrate gypsum, 6 parts of anhydrous sodium carbonate, and 25 parts of warm water.

[0042] Step S3, uniformly mixing the coal gangue powder with cement, dihydrate gypsum and silica fume to obtain a mixed powder.

[0043] Step S4: adding anhydrous sodium carbonate into warm water and mixing evenly to obtain alkaline solution.

[0044] Step S5, evenly apply a layer of machine oil on the inner wall of the disc of the disc granulator to prevent material adhesion, pour the mixed powder into the disc granulator, slowly spray alkali solution, and granulate in the disc granulator to obtain spherical particles. During the granulation process, the inclination angle of the disc granulator is 42°, the rotation speed is 38r / min, and spherical particles of 10mm are formed.

[0045] The spherical particles were placed in an environment with an air humidity of 60% and a temperature of 20° C. for aging for 1 day.

[0046] The aged spherical particles were placed in a 70°C rapid steam curing box for 24 hours and naturally cured at 20°C for 7 days.

[0047] Step S6, placing the cured spherical particles in an environment with a temperature of 50° C. for drying to obtain unfired ceramsite.

[0048] Embodiment 3 A method for preparing unburned ceramsite using coal gangue as raw material comprises the following steps: Step S1, drying the coal gangue at 105° C. for 12 h, ball-milling the coal gangue, and passing the mixture through a 100-mesh sieve to obtain coal gangue powder.

[0049] Step S2, weighing each material. In terms of weight, the amount of each material used is 65 parts of coal gangue powder, 21 parts of cement, 5 parts of silica fume, 4 parts of dihydrate gypsum, 6 parts of anhydrous sodium carbonate, and 25 parts of warm water.

[0050] Step S3, uniformly mixing the coal gangue powder with cement, dihydrate gypsum and silica fume to obtain a mixed powder.

[0051] Step S4: adding anhydrous sodium carbonate into warm water and mixing evenly to obtain alkaline solution.

[0052] Step S5, evenly apply a layer of machine oil on the inner wall of the disc of the disc granulator to prevent material adhesion, pour the mixed powder into the disc granulator, slowly spray alkali solution, and granulate in the disc granulator to obtain spherical particles. During the granulation process, the inclination angle of the disc granulator is 42°, the rotation speed is 38r / min, and spherical particles of 10mm are formed.

[0053] The spherical particles were placed in an environment with an air humidity of 60% and a temperature of 20° C. for aging for 1 day.

[0054] The aged spherical particles were placed in a 70°C rapid steam curing box for 24 hours and naturally cured at 20°C for 7 days.

[0055] Step S6, placing the cured spherical particles in an environment with a temperature of 50° C. for drying to obtain unfired ceramsite.

[0056] Embodiment 4 A method for preparing unburned ceramsite using coal gangue as raw material comprises the following steps: Step S1, drying the coal gangue at 105° C. for 12 h, ball-milling the coal gangue, and passing the mixture through a 100-mesh sieve to obtain coal gangue powder.

[0057] Step S2, weighing each material. In terms of weight, the amount of each material used is 65 parts of coal gangue powder, 21 parts of cement, 3 parts of silica fume, 3 parts of dihydrate gypsum, 6 parts of anhydrous sodium carbonate, and 25 parts of warm water.

[0058] Step S3, uniformly mixing the coal gangue powder with cement, dihydrate gypsum and silica fume to obtain a mixed powder.

[0059] Step S4: adding anhydrous sodium carbonate into warm water and mixing evenly to obtain alkaline solution.

[0060] Step S5, evenly apply a layer of machine oil on the inner wall of the disc of the disc granulator to prevent material adhesion, pour the mixed powder into the disc granulator, slowly spray alkali solution, and granulate in the disc granulator to obtain spherical particles. During the granulation process, the inclination angle of the disc granulator is 42°, the rotation speed is 38r / min, and spherical particles of 10mm are formed.

[0061] The spherical particles were placed in an environment with an air humidity of 60% and a temperature of 20° C. for aging for 1 day.

[0062] The aged spherical particles were placed in a 70°C rapid steam curing box for 24 hours and naturally cured at 20°C for 7 days.

[0063] Step S6, placing the cured spherical particles in an environment with a temperature of 50° C. for drying to obtain unfired ceramsite.

[0064] Embodiment 5 A method for preparing unburned ceramsite using coal gangue as raw material comprises the following steps: Step S1, drying the coal gangue at 105° C. for 12 h, ball-milling the coal gangue, and passing the mixture through a 100-mesh sieve to obtain coal gangue powder.

[0065] Step S2, weighing each material. In terms of weight, the amount of each material used is 65 parts of coal gangue powder, 21 parts of cement, 3 parts of silica fume, 3 parts of dihydrate gypsum, 4 parts of anhydrous sodium carbonate, and 25 parts of warm water.

[0066] Step S3, uniformly mixing the coal gangue powder with cement, dihydrate gypsum and silica fume to obtain a mixed powder.

[0067] Step S4: adding anhydrous sodium carbonate into warm water and mixing evenly to obtain alkaline solution.

[0068] Step S5, evenly apply a layer of machine oil on the inner wall of the disc of the disc granulator to prevent material adhesion, pour the mixed powder into the disc granulator, slowly spray alkali solution, and granulate in the disc granulator to obtain spherical particles. During the granulation process, the inclination angle of the disc granulator is 42°, the rotation speed is 38r / min, and spherical particles of 10mm are formed.

[0069] The spherical particles were placed in an environment with an air humidity of 60% and a temperature of 20° C. for aging for 1 day.

[0070] The aged spherical particles were placed in a 70°C rapid steam curing box for 24 hours and naturally cured at 20°C for 7 days.

[0071] Step S6, placing the cured spherical particles in an environment with a temperature of 50° C. for drying to obtain unfired ceramsite.

[0072] Comparative Example 1 A method for preparing unfired ceramsite comprises the following steps: Step S1, drying the coal gangue at 105° C. for 12 h, ball-milling the coal gangue, and passing the mixture through a 100-mesh sieve to obtain coal gangue powder.

[0073] Step S2, weighing each material. In terms of weight, the amount of each material used is 65 parts of coal gangue powder, 21 parts of cement, 3 parts of dihydrate gypsum, 6 parts of anhydrous sodium carbonate, and 25 parts of warm water.

[0074] Step S3, uniformly mixing the coal gangue powder, cement and dihydrate gypsum to obtain a mixed powder.

[0075] Step S4: adding anhydrous sodium carbonate into warm water and mixing evenly to obtain alkaline solution.

[0076] Step S5, evenly apply a layer of machine oil on the inner wall of the disc of the disc granulator to prevent material adhesion, pour the mixed powder into the disc granulator, slowly spray alkali solution, and granulate in the disc granulator to obtain spherical particles. During the granulation process, the inclination angle of the disc granulator is 42°, the rotation speed is 38r / min, and spherical particles of 10mm are formed.

[0077] The spherical particles were placed in an environment with an air humidity of 60% and a temperature of 20° C. for aging for 1 day.

[0078] The aged spherical particles were placed in a 70°C rapid steam curing box for 24 hours and naturally cured at 20°C for 7 days.

[0079] Step S6, placing the cured spherical particles in an environment with a temperature of 50° C. for drying to obtain unfired ceramsite.

[0080] Comparative Example 2 A method for preparing unburned ceramsite using coal gangue as raw material comprises the following steps: Step S1, drying the coal gangue at 105° C. for 12 h, ball-milling the coal gangue, and passing the mixture through a 100-mesh sieve to obtain coal gangue powder.

[0081] Step S2, weighing each material. In terms of weight, the amount of each material used is 65 parts of coal gangue powder, 21 parts of cement, 3 parts of silica fume, 3 parts of dihydrate gypsum, 6 parts of anhydrous sodium carbonate, and 25 parts of warm water.

[0082] Step S3, uniformly mixing the coal gangue powder with cement, dihydrate gypsum and silica fume to obtain a mixed powder.

[0083] Step S4: adding anhydrous sodium carbonate into warm water and mixing evenly to obtain alkaline solution.

[0084] Step S5, evenly apply a layer of machine oil on the inner wall of the disc of the disc granulator to prevent material adhesion, pour the mixed powder into the disc granulator, slowly spray alkali solution, and granulate in the disc granulator to obtain spherical particles. During the granulation process, the inclination angle of the disc granulator is 42°, the rotation speed is 38r / min, and spherical particles of 10mm are formed.

[0085] The spherical particles were placed in an environment with an air humidity of 60% and a temperature of 20° C. for aging for 1 day.

[0086] The aged spherical particles were placed in a 70°C rapid steam curing box for 24 hours and naturally cured at 20°C for 28 days.

[0087] Step S6, placing the cured spherical particles in an environment with a temperature of 50° C. for drying to obtain unfired ceramsite.

[0088] The unfired ceramsite prepared in Example 1, Example 2, Example 3, Example 4, Example 5, Comparative Example 1 and Comparative Example 2 was subjected to performance tests, and the test results are shown in Table 1.

[0089] Table 1 Performance test results ;

[0090] As can be seen from the above table, under the same preparation process conditions, the proportion of cementitious materials plays a key role. Comparative Example 1 shows that silica fume has a significant effect on the performance of unfired ceramsite, and adding an appropriate amount of silica fume can effectively improve its physical properties. Comparative Example 2 shows that the curing time has a greater impact on the performance of unfired ceramsite. Prolonging the curing time can enhance its mechanical properties, but at the same time the water absorption rate will decrease. This is because as the curing time increases, the hydration reaction of cementitious materials such as cement inside is more sufficient, and the structure formed is more compact.

[0091] Therefore, the present invention adopts the above-mentioned method for preparing unburned ceramsite using coal gangue as raw material, uses solid waste coal gangue powder as the main raw material, cement as the main cementitious material, anhydrous sodium carbonate, gypsum, and silica fume as auxiliary cementitious materials, and utilizes disc granulation to prepare unburned ceramsite that can be used in the construction industry, which can solve the problem of recycling of existing solid waste coal gangue, and thus realize the efficient recycling of coal gangue powder.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing unburned ceramsite using coal gangue as raw material, characterized in that: The following steps are involved: Step S1, drying the gangue at 100-110° C. for 10-14 h, ball-milling the gangue, and passing the mixture through a 100-mesh sieve to obtain gangue powder; Step S2, weighing each material; by weight, the amount of each material used is 60-70 parts of coal gangue powder, 20-23 parts of cement, 3-5 parts of silica fume, and 2-4 parts of dihydrate gypsum; 4-6 parts of anhydrous sodium carbonate, 25 parts of warm water; Step S3, mixing the coal gangue powder with cement, dihydrate gypsum and silica fume to obtain a mixed powder; Step S4, adding anhydrous sodium carbonate into warm water and mixing evenly to obtain alkali solution; Step S5, spraying the obtained alkali solution into the mixed powder in step S3, granulating, screening, aging and curing the spherical particles; Step S6, placing the cured spherical particles in an environment with a temperature of 50-70° C. for drying or natural drying to obtain unfired ceramsite.

2. The method for preparing unburned ceramsite using coal gangue as raw material according to claim 1, characterized in that: In step S2, the mass ratio of coal gangue powder to cement is 3:

1.

3. The method for preparing unburned ceramsite using coal gangue as raw material according to claim 1, characterized in that: In step S2, the mass proportions of the main chemical components contained in the coal gangue powder are: SiO2 50%-55%, Al2O3 30%-35%, and Fe2O3 2%-5%.

4. The method for preparing unburned ceramsite using coal gangue as raw material according to claim 1, characterized in that: In step S2, the cement is 42.5 grade standard cement; the silica fume fineness is 2000 mesh, the SiO2 content in the silica fume is greater than 95%; the sodium carbonate content in the anhydrous sodium carbonate is ≥99.8%.

5. The method for preparing unburned ceramsite using coal gangue as raw material according to claim 1, characterized in that: Granulation in step S5 specifically includes: evenly applying a layer of engine oil on the inner wall of the disc of the disc granulator, pouring the mixed powder into the disc granulator, slowly spraying alkali solution, and granulating in the disc granulator; during the granulation process, the inclination angle of the disc granulator is 40-44°, and the rotation speed is 36-40r / min.

6. The method for preparing unburned ceramsite using coal gangue as raw material according to claim 1, characterized in that: In step S5, the particle size of the spherical particles after screening is 5-10 mm; the water absorption rate of the spherical particles after screening is 9-17% in 1 hour, the single particle strength is 2-4 MPa, and the bulk density is 900-1000 kg·m -3 .

7. The method for preparing unburned ceramsite using coal gangue as raw material according to claim 1, characterized in that: The aging in step S5 is specifically aging for 1 day in an environment with an air humidity of 50-70% and a temperature of 18-22°C.

8. The method for preparing unburned ceramsite using coal gangue as raw material according to claim 1, characterized in that: The curing method in step S5 is specifically steam curing and natural curing; the temperature of steam curing is 65°C-75°C, and the curing time is 24h; the temperature of natural curing is 18-22°C, and the curing time is 7d.

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