Aluminate cement-based fireproof ultra-high performance concrete and preparation method thereof

Abstract

The invention discloses aluminate cement-based refractory ultra-high performance concrete and a preparation method thereof. The concrete is prepared from the following components in percentage by mass: 34.7 to 42.7 percent of raw material A50-A700 aluminate cement, 29.3 to 38.2 percent of fine aggregate, 8.4 to 22.2 percent of active admixture, 0 to 9.3 percent of steel fiber, 0.2 to 0.4 percent of water reducing agent and 7.3 to 7.8 percent of water. Uniformly mixing the cement, the active admixture and the water reducing agent to obtain primary powder; continuously adding fine aggregate under continuous stirring, uniformly stirring, adding water, and uniformly stirring to obtain primary slurry; uniformly scattering steel fibers into the primary slurry; pouring the obtained slurry into a mold and compacting by vibration; and putting the mixture into a standard curing box for curing, demolding, putting the obtained test piece into a high-temperature curing box for curing, and finally taking out the test piece and putting the test piece into a room to obtain the aluminate cement-based refractory ultra-high-performance concrete. The aluminate cement-based fire-resistant ultra-high performance concrete prepared by the invention has the advantages of ultra-high performance concrete, and also has the characteristics of burst resistance and excellent high temperature resistance.

Description

I. Technical Field:

[0001] This invention belongs to the field of building materials technology, specifically relating to an aluminate cement-based refractory ultra-high performance concrete and its preparation method. II. Background Technology:

[0002] Ultra-high performance concrete (UHPC) meets the requirements of civil engineering and building construction in many aspects, such as lightweighting, high-rise construction, large-span construction, heavy-duty construction, and durability, due to its outstanding technical advantages. However, because of its extremely dense microstructure, UHPC is prone to bursting under the high temperatures of a fire due to impeded steam escape. Furthermore, its mechanical properties degrade significantly after high temperatures, leading to a decrease in structural load-bearing capacity and even collapse, causing serious loss of life and property. Currently, most UHPCs use ordinary Portland cement as the cementing material. However, its main hydration products, such as calcium silicate gel and calcium hydroxide crystals, are easily decomposed at high temperatures, resulting in a significant decrease in the mechanical properties of the concrete. Especially when subjected to temperatures above 800℃, the strength loss of Portland cement-based UHPC is extremely severe, causing the concrete structure to essentially lose its load-bearing capacity. To fundamentally solve the problem of insufficient high-temperature performance of UHPC, it is necessary to select cementing materials with better fire resistance.

[0003] Aluminate cement is widely used in the refractory industry due to its high early strength and excellent high-temperature resistance. Compared with ordinary silicate cement, aluminate cement produces only a small amount of calcium hydroxide and hydrated calcium silicate gel during hydration, resulting in lower decomposition stress during high-temperature dehydration. Furthermore, the alumina formed after heating can react with refractory aggregates to generate a large amount of high-melting-point minerals. Compared with ordinary silicate cement-based UHPC, aluminate cement-based UHPC exhibits a significant strength advantage at higher temperatures. However, the type and quantity of hydrates in aluminate cement are greatly affected by the environment, with the main hydrate being CAH... 10 C2AH8 is unstable and easily transforms into the more stable C3AH6 with changes in temperature and humidity. Because C3AH6 has a higher density, it can lead to a 75% and 47% reduction in the volume of hardened cement paste, respectively. This significant increase in porosity severely reduces the load-bearing capacity of engineering structures, which is one of the reasons why aluminate cement has not been widely used in practical engineering. To solve these existing technical problems, there is an urgent need to develop a new type of aluminate cement-based refractory ultra-high performance concrete and its preparation method. III. Summary of the Invention:

[0004] The technical problem this invention aims to solve is: addressing the issues of easy cracking and poor high-temperature resistance in current silicate cement-based ultra-high performance concrete, this invention provides an aluminate cement-based refractory ultra-high performance concrete and its preparation method. The aluminate cement-based refractory ultra-high performance concrete prepared using this invention possesses the advantages of ultra-high performance concrete, and also exhibits anti-cracking and excellent high-temperature resistance.

[0005] To solve the above problems, the present invention adopts the following technical solution:

[0006] This invention provides an aluminate cement-based refractory ultra-high performance concrete, expressed as a percentage by mass, which is composed of 34.7-42.7% raw material cement, 29.3-38.2% fine aggregate, 8.4-22.2% active admixture, 0-9.3% steel fiber, 0.2-0.4% water-reducing agent, and 7.3-7.8% water.

[0007] The cement is CA50-A700 aluminate cement, with an alumina content of 50-60% and a specific surface area of ​​360 m². 2 / kg, density is 3g / cm³ 3 The active admixture is at least one of silica fume and fly ash.

[0008] According to the aforementioned aluminate cement-based refractory ultra-high performance concrete, the fine aggregate is quartz sand with a particle size of 0.08–2 mm and a density of 2.67 g / cm³, produced by Xiamen Aisio Standard Sand Co., Ltd. 3 The bulk density is 1.64 g / cm³. 3 .

[0009] According to the above-mentioned aluminate cement-based refractory ultra-high performance concrete, the silica fume contains ≥96% SiO2 and has an activity index of 105%; the fly ash is Grade I ultrafine fly ash with an average particle size of 21.2 μm, a loss on ignition of 0.41%, and an activity index of 120%.

[0010] According to the above-mentioned aluminate cement-based refractory ultra-high performance concrete, the steel fiber is a refractory steel fiber with a length of 13±1mm, an equivalent diameter of 0.18~0.23mm, and a tensile strength ≥2000MPa.

[0011] According to the above-mentioned aluminate cement-based refractory ultra-high performance concrete, the water-reducing agent is a polycarboxylate high-efficiency water-reducing agent, which is a white powder with a water reduction rate of 30-35%.

[0012] In addition, a method for preparing aluminate cement-based refractory ultra-high performance concrete is provided, characterized in that the preparation method includes the following steps:

[0013] S1. Weigh all raw materials according to the above-mentioned raw material ratio of aluminate cement-based refractory ultra-high performance concrete. Pour the weighed cement, active admixture and water-reducing agent into the mixer and mix them. Mix at low speed for 1 to 2 minutes until uniform to obtain primary powder.

[0014] S2. Under continuous stirring, add fine aggregate to the obtained primary powder and continue stirring at low speed for 1-2 minutes until the mixture is uniform.

[0015] S3. Under continuous stirring, add the weighed water to the material obtained in step S2, stir at low speed for 4-5 minutes, and stir evenly to obtain the primary slurry.

[0016] S4. Under continuous stirring, evenly sprinkle the weighed steel fibers into the obtained primary slurry, stir at low speed for 2-3 minutes, then stir at high speed for 1-2 minutes until the fibers are evenly distributed in the slurry.

[0017] S5. Pour the well-stirred slurry from step S4 evenly into a cubic mold with a side length of 40mm, and vibrate to compact it.

[0018] S6. Finally, the cast-in-place undemolded specimens are placed in a standard curing chamber for 24 hours and then demolded. After demolding, the specimens are immediately placed in a 90℃ high-temperature curing chamber for 72 hours, then removed and placed indoors for 28 days to obtain aluminate cement-based refractory ultra-high performance concrete.

[0019] According to the above-mentioned method for preparing aluminate cement-based refractory ultra-high performance concrete, the characteristic is that the speed of low-speed stirring in steps S1 to S4 is 100 to 140 rpm.

[0020] According to the above-mentioned method for preparing aluminate cement-based refractory ultra-high performance concrete, the speed of high-speed mixing in step S4 is 250-280 rpm.

[0021] According to the above-mentioned preparation method of aluminate cement-based refractory ultra-high performance concrete, the temperature inside the standard curing chamber in step S6 is 20±2℃ and the relative humidity is ≥90%.

[0022] The positive and beneficial effects of this invention are as follows:

[0023] 1. The CA50-A700 aluminate cement used in the technical solution of this invention has better high temperature resistance than ordinary silicate cement. The selection of aluminate cement as the main cementing material for refractory UHPC expands the development and application of UHPC.

[0024] 2. The technical solution of this invention effectively improves the anti-cracking performance and mechanical properties of aluminate-based UHPC after high temperature by using reasonable raw material ratio and preparation process. After high temperature calcination at 800℃ and 1000℃, the compressive strength of the concrete can reach as low as 87.9MPa and 59.9MPa, respectively. Moreover, the specimens after high temperature did not crack and remained intact.

[0025] 3. In the preparation method of the present invention, the use of heat curing can not only avoid the formation of unstable hydrates, but also accelerate the hydration process, generate more hydrates with more stable properties, and improve the early strength of UHPC.

[0026] 4. The technical solution of this invention uses industrial waste to replace cement, turning waste into treasure. It not only reduces the amount of cement used, but also inhibits the formation of unstable hydrates, thereby preparing aluminate cement-based refractory UHPC with excellent high-temperature resistance, which has good economic and social benefits. IV. Detailed Implementation Methods:

[0027] The specific embodiments are merely illustrative of the present invention and are not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to these embodiments without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of the present invention.

[0028] In the following examples, the cement used is CA50-A700 aluminate cement, with an alumina content of 50-60% and a specific surface area of ​​360 m². 2 / kg, density is 3g / cm³ 3 The fine aggregate is quartz sand with a particle size of 0.08–2 mm and a density of 2.67 g / cm³. 3 The bulk density is 1.64 g / cm³. 3 The silica fume contains ≥96% SiO2 and has an activity index of 105%; the fly ash is Grade I ultrafine fly ash with an average particle size of 21.2 μm, a loss on ignition of 0.41%, and an activity index of 120%; the steel fiber is refractory steel fiber with a length of 13±1 mm, an equivalent diameter of 0.18–0.23 mm, and a tensile strength ≥2000 MPa; the water-reducing agent is a polycarboxylate high-efficiency water-reducing agent, which is a white powder with a water reduction rate of 30–35%.

[0029] Example 1:

[0030] The aluminate cement-based refractory ultra-high performance concrete of the present invention is composed of 40.6% aluminate cement, 35.4% quartz sand, 4.2% silica fume, 9.2% fly ash, 3.1% steel fiber, 0.2% water-reducing agent and 7.3% water, expressed as a percentage by mass. For details of each component and its content, please refer to Table 1.

[0031] Example 2:

[0032] The aluminate cement-based refractory ultra-high performance concrete of the present invention is composed of raw materials: 37.9% aluminate cement, 33.7% quartz sand, 8.4% silica fume, 9.2% fly ash, 3.1% steel fiber, 0.2% water-reducing agent, and 7.5% water, expressed as a percentage by mass. For details of each component and its content, please refer to Table 1.

[0033] Example 3:

[0034] The aluminate cement-based refractory ultra-high performance concrete of the present invention, expressed as a percentage by mass, is composed of raw materials: 35.1% aluminate cement, 32.1% quartz sand, 12.6% silica fume, 9.2% fly ash, 3.1% steel fiber, 0.2% water-reducing agent, and 7.7% water. The components and their contents are detailed in Table 1.

[0035] Example 4:

[0036] The aluminate cement-based refractory ultra-high performance concrete of the present invention is composed of 42.1% aluminate cement, 34.3% quartz sand, 8.4% silica fume, 4.6% fly ash, 3.1% steel fiber, 0.2% water-reducing agent and 7.3% water, expressed as a percentage by mass. For details of each component and its content, please refer to Table 1.

[0037] Example 5:

[0038] The aluminate cement-based refractory ultra-high performance concrete of the present invention is composed of raw materials: 34.7% aluminate cement, 32.1% quartz sand, 8.4% silica fume, 13.8% fly ash, 3.1% steel fiber, 0.2% water-reducing agent and 7.7% water, expressed as a percentage by mass. For details of each component and its content, please refer to Table 1.

[0039] Example 6:

[0040] The aluminate cement-based refractory ultra-high performance concrete of the present invention is composed of raw materials: 39.9% aluminate cement, 30.2% quartz sand, 7.5% silica fume, 8.1% fly ash, 6.2% steel fiber, 0.3% water-reducing agent, and 7.8% water, expressed as a percentage by mass. For details of each component and its content, please refer to Table 1.

[0041] Example 7:

[0042] The aluminate cement-based refractory ultra-high performance concrete of the present invention is composed of raw materials: 38.2% aluminate cement, 29.3% quartz sand, 7.1% silica fume, 7.9% fly ash, 9.3% steel fiber, 0.4% water-reducing agent, and 7.8% water, expressed as a percentage by mass. For details of each component and its content, please refer to Table 1.

[0043] In the following comparative examples 1 to 3, the cement used was CA50-A700 aluminate cement, with an alumina content of 50-60% and a specific surface area of ​​360 m². 2 / kg, density is 3g / cm³ 3 The fine aggregate is quartz sand with a particle size of 0.08–2 mm and a density of 2.67 g / cm³. 3 The bulk density is 1.64 g / cm³. 3 The silica fume contains ≥96% SiO2 and has an activity index of 105%; the fly ash is Grade I ultrafine fly ash with an average particle size of 21.2 μm, a loss on ignition of 0.41%, and an activity index of 120%; the steel fiber is refractory steel fiber with a length of 13±1 mm, an equivalent diameter of 0.18–0.23 mm, and a tensile strength ≥2000 MPa; the water-reducing agent is a polycarboxylate high-efficiency water-reducing agent, which is a white powder with a water reduction rate of 30–35%.

[0044] Comparative Example 1:

[0045] A type of aluminate cement-based refractory ultra-high performance concrete, expressed as a percentage by mass, is composed of 40.1% aluminate cement, 34.3% quartz sand, 8.4% silica fume, 9.2% fly ash, 0.2% water-reducing agent, and 7.8% water. The components and their contents are detailed in Table 1.

[0046] Comparative Example 2:

[0047] A type of aluminate cement-based refractory ultra-high performance concrete, expressed as a percentage by mass, is composed of 41.5% aluminate cement, 38.2% quartz sand, 9.2% fly ash, 3.1% steel fiber, 0.2% water-reducing agent, and 7.8% water. The components and their contents are detailed in Table 1.

[0048] Comparative Example 3:

[0049] A type of aluminate cement-based refractory ultra-high performance concrete, expressed as a percentage by mass, is composed of 42.7% aluminate cement, 37.8% quartz sand, 8.4% silica fume, 3.1% steel fiber, 0.2% water-reducing agent, and 7.8% water. The components and their contents are detailed in Table 1.

[0050] In Comparative Example 4 below, ordinary Portland cement was used, with a specific surface area of ​​355 m². 2 / kg, density is 3.08g / cm³ 3 The fine aggregate is quartz sand with a particle size of 0.08–2 mm and a density of 2.67 g / cm³. 3 The bulk density is 1.64 g / cm³. 3The silica fume contains ≥96% SiO2 and has an activity index of 105%; the fly ash is Grade I ultrafine fly ash with an average particle size of 21.2 μm, a loss on ignition of 0.41%, and an activity index of 120%; the steel fiber is refractory steel fiber with a length of 13±1 mm, an equivalent diameter of 0.18–0.23 mm, and a tensile strength ≥2000 MPa; the water-reducing agent is a polycarboxylate high-efficiency water-reducing agent, which is a white powder with a water reduction rate of 30–35%.

[0051] Comparative Example 4:

[0052] A type of aluminate cement-based refractory ultra-high performance concrete, expressed as a percentage by mass, is composed of raw materials: 39.6% silicate cement, 31.7% quartz sand, 8.4% silica fume, 9.2% fly ash, 3.1% steel fiber, 0.2% water-reducing agent, and 7.8% water. The components and their contents are detailed in Table 1.

[0053] Table 1. Proportions of raw materials used in Examples 1-7 and Comparative Examples 1-4 of the present invention.

[0054] cement Quartz sand silica ash fly ash Steel Fiber Water reducing agent water Example 1 40.6 35.4 4.2 9.2 3.1 0.2 7.3 Example 2 37.9 33.7 8.4 9.2 3.1 0.2 7.5 Example 3 35.1 32.1 12.6 9.2 3.1 0.2 7.7 Example 4 42.1 34.3 8.4 4.6 3.1 0.2 7.3 Example 5 34.7 32.1 8.4 13.8 3.1 0.2 7.7 Example 6 39.9 30.2 7.5 8.1 6.2 0.3 7.8 Example 7 38.2 29.3 7.1 7.9 9.3 0.4 7.8 Comparative Example 1 40.1 34.3 8.4 9.2 0 0.2 7.8 Comparative Example 2 41.5 38.2 0 9.2 3.1 0.2 7.8 Comparative Example 3 42.7 37.8 8.4 0 3.1 0.2 7.8 Comparative Example 4 39.6 31.7 8.4 9.2 3.1 0.2 7.8

[0055] The detailed steps of the preparation methods of aluminate cement-based refractory ultra-high performance concrete in Examples 1-7 and Comparative Examples 1-4 of the present invention are as follows:

[0056] S1. Weigh out various raw materials according to the raw material proportions of any of the aluminate cement-based refractory ultra-high performance concrete described in Examples 1 to 7 and Comparative Examples 1 to 4. Pour the weighed cement, active admixture and water-reducing agent into a mixer and mix them. Stir at 120 rpm for 2 minutes until uniformly mixed to obtain primary powder.

[0057] S2. Under continuous stirring, add fine aggregate to the obtained primary powder and continue stirring at 120 rpm for 2 minutes until uniform.

[0058] S3. Under continuous stirring, add the weighed water to the material obtained in step S2, and stir at 120 rpm for 5 minutes until uniform to obtain the primary slurry.

[0059] S4. Under continuous stirring, the weighed steel fibers are evenly sprinkled into the obtained primary slurry, stirred at 120 rpm for 2 minutes, and then stirred at 260 rpm for 2 minutes until the fibers are evenly distributed in the slurry.

[0060] S5. Pour the well-stirred slurry from step S4 evenly into a cubic mold with a side length of 40mm, and vibrate to compact it.

[0061] S6. Finally, place the cast and shaped undemolded specimens in a standard curing chamber (temperature inside the chamber is 20±2℃, relative humidity ≥90%) for 24 hours, and then demold them. After demolding, immediately place the obtained specimens in a 90℃ high-temperature curing chamber for 72 hours, and then take them out and place them indoors for 28 days to obtain aluminate cement-based refractory ultra-high performance concrete.

[0062] High-temperature test: Aluminate cement-based refractory ultra-high performance concrete cube specimens that had reached 28 days of age and required high-temperature testing were first baked in a 105℃ oven for 24 hours. After cooling to room temperature, they were placed in a high-temperature resistance furnace for the high-temperature test. The actual heating rate in the furnace was 3℃ / min. After reaching the target temperature, the specimens were held at that temperature for 3 hours and finally allowed to cool naturally to room temperature. The heating temperatures in this test were 200℃, 400℃, 600℃, 800℃, and 1000℃.

[0063] High-temperature cube compressive strength test: The compressive strength of aluminate cement-based refractory ultra-high performance concrete specimens after different temperatures was tested according to the provisions of GB / T17671-2020 "Test Method for Strength of Cement Mortar". The test results of compressive strength after different temperatures are shown in Table 2.

[0064] Table 2. Performance test results of the products prepared in Examples 1-7 and Comparative Examples 1-4 of this invention.

[0065]

[0066] Table 2 shows the data, where Comparative Example 1 is a comparison test of Examples 2, 7, and 8. As can be seen from the data in Table 2, compared to specimens without refractory steel fibers, aluminate cement-based refractory ultra-high performance concrete specimens with steel fibers of 3.1%, 6.2%, and 9.3% all showed significant increases in compressive strength at any temperature, with increases exceeding 15%. The largest increases in compressive strength were observed after exposure to 400℃, with increases of 30.6%, 45.5%, and 60.21%, respectively.

[0067] Comparative Example 2 is a comparison test of Examples 1, 2, and 3. As can be seen from the data in Table 2, compared to specimens without silica fume, the compressive strength of aluminate cement-based refractory ultra-high performance concrete specimens with silica fume content of 4.2%, 8.4%, and 12.6% showed a trend of first increasing and then decreasing, with the compressive strength reaching its maximum at any temperature when the silica fume content was 4.2%.

[0068] Comparative Example 3 is a comparison test of Examples 2, 4, and 5. As can be seen from the data in Table 2, compared to specimens without fly ash, the compressive strength of aluminate cement-based refractory ultra-high performance concrete specimens with fly ash content of 4.6%, 9.2%, and 13.8% showed a trend of first increasing and then decreasing, with the compressive strength reaching its maximum at any temperature when the fly ash content was 9.2%.

[0069] Comparative Example 4 is a comparative test of Example 2. As can be seen from the data in Table 2, when the temperature is 20℃ or 200℃, the compressive strength of the aluminate cement-based refractory ultra-high performance concrete specimens with the same cement content is lower than that of the silicate cement-based ultra-high performance concrete specimens. However, when the temperatures are 400℃, 600℃, and 800℃, the compressive strength of the aluminate cement-based refractory ultra-high performance concrete specimens is significantly greater than that of the silicate cement ultra-high performance concrete specimens, increasing by 6.4%, 8.9%, and 17.8%, respectively. When the temperature is 1000℃, the silicate cement ultra-high performance concrete specimens cracked, while the aluminate cement-based refractory ultra-high performance concrete specimens remained intact.

[0070] 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 the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An aluminate cement-based refractory ultra-high performance concrete, characterized in that: Expressed as a percentage by mass, the aluminate cement-based refractory ultra-high performance concrete is composed of 34.7-42.7% raw material cement, 29.3-38.2% fine aggregate, 8.4-22.2% active admixture, 0-9.3% steel fiber, 0.2-0.4% water-reducing agent, and 7.3-7.8% water. The cement is CA50-A700 aluminate cement, with an alumina content of 50-60% and a specific surface area of ​​360 m². 2 / kg, density is 3g / cm³ 3 The active admixture is at least one of silica fume and fly ash.

2. The aluminate cement-based refractory ultra-high performance concrete according to claim 1, characterized in that: The fine aggregate is quartz sand with a particle size of 0.08–2 mm, produced by Xiamen Aisio Standard Sand Co., Ltd., and a density of 2.67 g / cm³. 3 The bulk density is 1.64 g / cm³. 3 .

3. The aluminate cement-based refractory ultra-high performance concrete according to claim 1, characterized in that: The silica fume contains ≥96% SiO2 and has an activity index of 105%; the fly ash is Grade I ultrafine fly ash with an average particle size of 21.2 μm, a loss on ignition of 0.41%, and an activity index of 120%.

4. The aluminate cement-based refractory ultra-high performance concrete according to claim 1, characterized in that: The steel fiber is a fire-resistant steel fiber with a length of 13±1mm, an equivalent diameter of 0.18~0.23mm, and a tensile strength ≥2000MPa.

5. The aluminate cement-based refractory ultra-high performance concrete according to claim 1, characterized in that: The water-reducing agent is a polycarboxylate superplasticizer, which is a white powder with a water reduction rate of 30-35%.

6. A method for preparing aluminate cement-based refractory ultra-high performance concrete, characterized in that, The preparation method includes the following steps: S1. Weigh various raw materials according to the raw material proportion of the aluminate cement-based refractory ultra-high performance concrete as described in claim 1, pour the weighed cement, active admixture and water-reducing agent into the mixer for mixing, stir at low speed for 1 to 2 minutes, and stir evenly to obtain primary powder. S2. Under continuous stirring, add fine aggregate to the obtained primary powder and continue stirring at low speed for 1-2 minutes until the mixture is uniform. S3. Under continuous stirring, add the weighed water to the material obtained in step S2, stir at low speed for 4-5 minutes, and stir evenly to obtain the primary slurry. S4. Under continuous stirring, evenly sprinkle the weighed steel fibers into the obtained primary slurry, stir at low speed for 2-3 minutes, then stir at high speed for 1-2 minutes until the fibers are evenly distributed in the slurry. S5. Pour the well-stirred slurry from step S4 evenly into a cubic mold with a side length of 40mm, and vibrate to compact it. S6. Finally, the cast-in-place undemolded specimens are placed in a standard curing chamber for 24 hours and then demolded. After demolding, the specimens are immediately placed in a 90℃ high-temperature curing chamber for 72 hours, then removed and placed indoors for 28 days to obtain aluminate cement-based refractory ultra-high performance concrete.

7. The method for preparing aluminate cement-based refractory ultra-high performance concrete according to claim 6, characterized in that: The speed of low-speed stirring in steps S1 to S4 is 100 to 140 rpm.

8. The method for preparing aluminate cement-based refractory ultra-high performance concrete according to claim 6, characterized in that: The speed of high-speed stirring in step S4 is 250-280 rpm.

9. The method for preparing aluminate cement-based refractory ultra-high performance concrete according to claim 6, characterized in that: The temperature inside the standard curing chamber in step S6 is 20±2℃ and the relative humidity is ≥90%.

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