Method for preparing multi-scale fiber-reinforced jetted uhp using carbon mineralization reaction

Abstract

The application discloses a method for preparing a multi-scale fiber toughened jet UHPC by using carbon mineralization reaction, and comprises the following steps: step S1: weighing cement, fly ash floating bead, silica fume, ultra-fine limestone powder, micro-fiber steel fiber, mixed water, nano-texture and porous aggregate; step S2: soaking the porous aggregate in a magnesium chloride solution, taking out and draining to obtain pre-wetted porous aggregate, and then mixing the pre-wetted porous aggregate with other raw materials to prepare jet ultra-high performance concrete; and step S3: pumping the jet ultra-high performance concrete obtained in step S2 by using industrial waste gas with a temperature of 60-80 DEG C and a carbon dioxide concentration of 50-70 vol%, to obtain a jet UHPC test piece and perform maintenance. By using high-temperature carbon dioxide jet UHPC, pre-adsorbing magnesium chloride on the porous aggregate and nano-crystal core induction, the effect of multi-scale toughening is achieved, and a large amount of carbon dioxide industrial waste gas is consumed.

Description

Technical Field

[0001] This invention relates to ultra-high performance concrete, specifically to a method for preparing multi-scale fiber-reinforced sprayed UHPC using a carbon mineralization reaction. Background Technology

[0002] Ultra-high performance concrete (UHPC) is a new type of building material with excellent mechanical properties and high impermeability. To expand its application in practical engineering, UHPC is used in shotcrete construction as a material for the renovation, repair, and reinforcement of damaged buildings. However, to maintain the pumpability of shotcrete, the length and amount of steel fibers used need to be reduced, which leads to a decrease in the tensile strength and toughness of the shotcrete.

[0003] Carbon emissions and their environmental impact are receiving increasing attention, and reducing greenhouse gases has become a priority for the construction industry. Carbon dioxide mineralization refers to the carbonation reaction between carbon dioxide and cement hydration products such as Ca(OH)₂, CSH, and Aft in cement-based materials, producing calcium carbonate microparticles and amorphous silica gel. Depending on the reaction conditions, the resulting calcium carbonate microparticles can be classified into three forms: aragonite, aragonite, and calcite. Aragonite, with its long rod-like structure, can be used as a toughening material in concrete. Industrial waste gases from petroleum refining, steelmaking, and coal-fired power generation contain large amounts of carbon dioxide; effective utilization of these gases can reduce carbon emissions.

[0004] Therefore, it is necessary to develop a method for preparing multi-scale fiber-toughened sprayed UHPC using carbon mineralization reaction, which can improve the toughness and tensile strength of UHPC, consume carbon dioxide industrial waste gas, and achieve multi-scale fiber toughening. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a method for preparing multi-scale fiber-toughened sprayed UHPC using carbon mineralization reaction, thereby improving the toughness and tensile strength of UHPC, consuming carbon dioxide industrial waste gas, and realizing multi-scale fiber toughening.

[0006] The technical solution of this invention is: a method for preparing multi-scale fiber-toughened sprayed UHPC using a carbon mineralization reaction, characterized by comprising the following steps:

[0007] Step S1: Weigh the following raw materials by weight: 300-400 parts cement, 40-100 parts fly ash cenospheres, 50-100 parts silica fume, 40-70 parts ultrafine limestone powder, 30-70 parts microfiber steel, 90-120 parts mixing water, 5-20 parts nano aragonite, and 300-400 parts porous aggregate.

[0008] Step S2: Soak the porous aggregate weighed in step S1 in magnesium chloride solution to fully absorb the magnesium chloride solution, take it out and drain it to obtain pre-wetted porous aggregate. Then mix the pre-wetted porous aggregate with cement, fly ash cenospheres, silica fume, ultrafine limestone powder, microfiber steel fiber, mixing water and nano aragonite weighed in step S1 to prepare sprayed ultra-high performance concrete.

[0009] Step S3: Using industrial waste gas with a temperature of 60℃~80℃ and a carbon dioxide concentration of 50~70vt%, the sprayed ultra-high performance concrete obtained in step S2 is pumped to obtain sprayed UHPC specimens and then cured.

[0010] Preferably, in step S1, the porous aggregate is zeolite and / or pumice with a particle size in the range of 0.45 mm to 0.90 mm and a water absorption rate in the range of 30% to 50%.

[0011] Preferably, in step S2, the concentration of the magnesium chloride solution is 0.025 mol / L to 0.05 mol / L.

[0012] Preferably, in step S2, the sample is soaked in a magnesium chloride solution for 24-48 hours.

[0013] Preferably, in step S1, the cement is silicate cement with a strength of not less than 42.5; the fly ash cenospheres have an average particle size of 1–5 μm and a specific surface area greater than 2500 m². 2 / kg.

[0014] Preferably, in step S1, the silica fume has a SiO2 content greater than 90% and a specific surface area greater than 20,000 m². 2 / kg; the CaCO3 content of the ultrafine limestone powder is greater than 95%, and the average particle size is not greater than 80nm.

[0015] Preferably, in step S1, the aspect ratio of the microfiber steel fiber is 50-70 and the diameter is 0.2-0.3 mm; the aspect ratio of the nano-aragonite is 10-15 and the diameter is 40-60 nm.

[0016] Preferably, in step S2, the mixing preparation specifically includes:

[0017] 1) Thoroughly mix cement, fly ash cenospheres, silica fume, ultrafine limestone powder, pre-wetted porous aggregate, and nano-aragonite, and dry mix for 1-2 minutes;

[0018] 2) Add the mixing water and mix for 3-5 minutes;

[0019] 3) Add microfiber steel and continue stirring for 2-4 minutes to obtain sprayed ultra-high performance concrete.

[0020] Preferably, in step S3, the gas pressure during pumping is 0.4 to 0.8 MPa.

[0021] Preferably, in step S3, industrial waste gas with a temperature of 70-80°C and a carbon dioxide concentration of 60 wt% is used.

[0022] This invention employs a method of injecting UHPC (Ultra-High-Temperature Polymer) with high-temperature (60℃~80℃) carbon dioxide-containing waste gas through an air compressor. It utilizes porous aggregate pre-adsorbed magnesium chloride solution to react with carbon dioxide, generating a saturated magnesium hydroxide solution that acts as a crystal stabilizer for aragonite. Finally, nano-aragonite is incorporated as a nucleation inducing agent, thus providing a suitable carbon mineralization reaction environment for aragonite formation. This promotes the carbon dioxide mineralization reaction to generate toughening aragonite, achieving multi-scale toughening. This solves the problem of reduced tensile strength and toughness in injected UHPC caused by short steel fiber length and low steel fiber content. Furthermore, this method provides direction for the consumption of carbon dioxide and the promotion and application of injected UHPC. The combination of these two approaches expands the application range of concrete and has good economic and environmental benefits.

[0023] Compared with the prior art, the present invention has the following obvious advantages:

[0024] (1) Porous aggregates have a high water absorption rate and can effectively adsorb magnesium chloride solution. They also have the ability to directly adsorb carbon dioxide. During the spraying process, porous materials adsorb carbon dioxide. When mixed into sprayed UHPC, the solution can be released into the concrete in a short time. In the solution, high-temperature carbon dioxide and cement hydration products undergo a mineralization reaction to generate aragonite, thereby improving the tensile strength and toughness of sprayed UHPC.

[0025] (2) High-temperature carbon dioxide injection of UHPC can consume a large amount of carbon dioxide industrial waste gas. On this basis, it can be well combined with the injection of UHPC. It can not only provide carbon dioxide and temperature environment for the formation of aragonite with cement hydration products in magnesium chloride solution, but also allow carbon dioxide to react with the cement hydration products in the internal slurry to form calcite, which makes the injection of UHPC denser. High temperature can accelerate the cement hydration reaction and improve the early compressive strength of injection of UHPC.

[0026] (3) Nano-aragonite can not only act as a crystal nucleus to induce carbon dioxide mineralization reaction in the slurry, increasing the formation rate of aragonite and enhancing the toughness of concrete, but it can also act as a microfiber in sprayed UHPC to achieve fiber toughening, further improving the toughness of sprayed UHPC. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the following embodiments provide a more detailed description of the invention. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Unless otherwise specified, the pharmaceuticals used in the embodiments are commercially available products, and the methods used are conventional methods in the art. The raw materials for Embodiments 1-4 of this invention are shown in Table 1.

[0028] Table 1 Raw materials used in UHPC

[0029]

[0030] The specific raw material parameters used in Examples 1-4 and Comparative Examples 1-3 are as follows:

[0031] Cement: Portland cement with a strength grade of 42.5;

[0032] Fly ash cenospheres: average particle size 1-5μm, specific surface area 2500-2800m² 2 / kg;

[0033] The silica fume has a SiO2 content of 94% and a specific surface area ranging from 20,000 to 22,000 m². 2 / kg;

[0034] The CaCO3 content of the ultrafine limestone powder is greater than 95%, and the average particle size is 60-70 nm.

[0035] The porous aggregate is zeolite with a particle size in the range of 0.45-0.9mm and a water absorption rate of 30-40%.

[0036] The microfibers have an aspect ratio of 65 and a diameter of 0.2 mm.

[0037] The mixing water is concrete water that meets national standards;

[0038] Nano-aragonite has an aspect ratio of 10-15 and a diameter of 40-60 nm.

[0039] Example 1

[0040] This embodiment provides a method for preparing multi-scale fiber-toughened sprayed UHPC using a carbon mineralization reaction, including the following steps:

[0041] Step S1: Weigh the following raw materials according to Table 1: 300 parts cement, 100 parts fly ash cenospheres, 90 parts silica fume, 70 parts ultrafine limestone powder, 60 parts microfiber steel, 100 parts mixing water, 10 parts nano aragonite, and 320 parts porous aggregate (in this embodiment, the porous aggregate is zeolite).

[0042] Step S2: The porous aggregate weighed in Step S1 is soaked in a 0.025 mol / L magnesium chloride solution for 24 hours to fully absorb the magnesium chloride solution. After soaking, it is drained (drained means no liquid drips from the surface) to obtain pre-wetted porous aggregate. The pre-wetted porous aggregate is then mixed with the remaining raw materials from Step S1 to prepare sprayed ultra-high performance concrete. The specific mixing process is as follows.

[0043] 1) Thoroughly mix cement, fly ash cenospheres, silica fume, ultrafine limestone powder, pre-wetted porous aggregate, and nano-aragonite, and dry mix for 1-2 minutes;

[0044] 2) Add water for mixing and mix for 3-5 minutes;

[0045] 3) Add microfiber steel and continue stirring for 2-4 minutes to obtain sprayed ultra-high performance concrete.

[0046] Step S3: Connect industrial waste gas at 60℃ with a carbon dioxide concentration of 50vt% to an air compressor. First, turn on the pumping equipment, then turn on the air compressor. Use the industrial waste gas at a pressure of 0.4-0.8 MPa to pump the sprayed ultra-high performance concrete obtained in step S2 to obtain sprayed UHPC specimens and perform curing.

[0047] Example 2

[0048] This embodiment provides a method for preparing multi-scale fiber-toughened sprayed UHPC using a carbon mineralization reaction, including the following steps:

[0049] Step S1: Weigh the following raw materials according to Table 1: 350 parts cement, 60 parts fly ash cenospheres, 90 parts silica fume, 60 parts ultrafine limestone powder, 60 parts microfiber steel, 100 parts mixing water, 10 parts nano aragonite, and 336 parts porous aggregate (in this embodiment, the porous aggregate is zeolite).

[0050] Step S2: The porous aggregate weighed in Step S1 is soaked in a 0.035 mol / L magnesium chloride solution for 24 hours to fully absorb the magnesium chloride solution. After draining, pre-wetted porous aggregate is obtained. The pre-wetted porous aggregate is then mixed with the remaining raw materials from Step S1 to prepare sprayed ultra-high performance concrete. The specific mixing process is as follows.

[0051] 1) Thoroughly mix cement, fly ash cenospheres, silica fume, ultrafine limestone powder, pre-wetted porous aggregate, and nano-aragonite, and dry mix for 1-2 minutes;

[0052] 2) Add water for mixing and mix for 3-5 minutes;

[0053] 3) Add microfiber steel and continue stirring for 2-4 minutes to obtain sprayed ultra-high performance concrete.

[0054] Step S3: Connect industrial waste gas at 70℃ with a carbon dioxide concentration of 60vt% to an air compressor. First, turn on the pumping equipment, then turn on the air compressor. Use the industrial waste gas at a pressure of 0.4-0.8 MPa to pump the sprayed ultra-high performance concrete obtained in step S2 to obtain sprayed UHPC specimens and perform curing.

[0055] Example 3

[0056] This embodiment provides a method for preparing multi-scale fiber-toughened sprayed UHPC using a carbon mineralization reaction, including the following steps:

[0057] Step S1: Weigh the following raw materials according to Table 1: 350 parts cement, 50 parts fly ash cenospheres, 90 parts silica fume, 50 parts ultrafine limestone powder, 60 parts microfiber steel, 100 parts mixing water, 10 parts nano aragonite, and 346 parts porous aggregate (in this embodiment, the porous aggregate is zeolite).

[0058] Step S2: The porous aggregate weighed in Step S1 is soaked in a 0.05 mol / L magnesium chloride solution for 24 hours to fully absorb the magnesium chloride solution. After draining, pre-wetted porous aggregate is obtained. The pre-wetted porous aggregate is then mixed with the remaining raw materials from Step S1 to prepare sprayed ultra-high performance concrete. The specific mixing process is as follows.

[0059] 1) Thoroughly mix cement, fly ash cenospheres, silica fume, ultrafine limestone powder, pre-wetted porous aggregate, and nano-aragonite, and dry mix for 1-2 minutes;

[0060] 2) Add water for mixing and mix for 3-5 minutes;

[0061] 3) Add microfiber steel and continue stirring for 2-4 minutes to obtain sprayed ultra-high performance concrete.

[0062] Step S3: Connect industrial waste gas at 70℃ with a carbon dioxide concentration of 60vt% to an air compressor. First, turn on the pumping equipment, then turn on the air compressor. Use the industrial waste gas at a pressure of 0.4-0.8 MPa to pump the sprayed ultra-high performance concrete obtained in step S2 to obtain sprayed UHPC specimens and perform curing.

[0063] Example 4

[0064] This embodiment provides a method for preparing multi-scale fiber-toughened sprayed UHPC using a carbon mineralization reaction, including the following steps:

[0065] Step S1: Weigh the following raw materials according to Table 1: 400 parts cement, 40 parts fly ash cenospheres, 60 parts silica fume, 50 parts ultrafine limestone powder, 60 parts microfiber steel, 100 parts mixing water, 20 parts nano aragonite, and 360 parts porous aggregate (in this embodiment, the porous aggregate is zeolite).

[0066] Step S2: The porous aggregate weighed in Step S1 is soaked in a 0.05 mol / L magnesium chloride solution for 24 hours to fully absorb the magnesium chloride solution. After draining, pre-wetted porous aggregate is obtained. The pre-wetted porous aggregate is then mixed with the remaining raw materials from Step S1 to prepare sprayed ultra-high performance concrete. The specific mixing process is as follows.

[0067] 1) Thoroughly mix cement, fly ash cenospheres, silica fume, ultrafine limestone powder, pre-wetted porous aggregate, and nano-aragonite, and dry mix for 1-2 minutes;

[0068] 2) Add water for mixing and mix for 3-5 minutes;

[0069] 3) Add microfiber steel and continue stirring for 2-4 minutes to obtain sprayed ultra-high performance concrete.

[0070] Step S3: Connect industrial waste gas at 80℃ with a carbon dioxide concentration of 60vt% to an air compressor. First, turn on the pumping equipment, then turn on the air compressor. Use the industrial waste gas at a pressure of 0.4-0.8 MPa to pump the sprayed ultra-high performance concrete obtained in step S2 to obtain sprayed UHPC specimens and perform curing.

[0071] Comparative Example 1

[0072] This comparative example provides a method for preparing sprayed UHPC without using magnesium chloride pre-wetting, without adding nano-aragonite, and without implementing carbon dioxide mineralization curing; the method uses only conventional curing for sprayed UHPC, including the following steps:

[0073] Step S1: Weigh the following raw materials by weight: 350 parts cement, 60 parts fly ash cenospheres, 90 parts silica fume, 60 parts ultrafine limestone powder, 60 parts microfiber steel, 100 parts mixing water, and 336 parts porous aggregate (zeolite).

[0074] Step S2: Soak the porous aggregate weighed in Step S1 in tap water for 24 hours for pretreatment, drain, and set aside to obtain pre-wetted porous aggregate. Then, mix the pre-wetted porous aggregate with the remaining raw materials from Step S1 to prepare sprayed ultra-high performance concrete. The specific mixing process is as follows:

[0075] 1) Thoroughly mix cement, fly ash cenospheres, silica fume, ultrafine limestone powder, and pre-wetted porous aggregate, and dry mix for 1-2 minutes;

[0076] 2) Add the mixing water and mix for 3-5 minutes;

[0077] 3) Add microfiber steel and continue stirring for 2-4 minutes to obtain sprayed ultra-high performance concrete.

[0078] Step S3: Place the specimen into a pumping device and spray UHPC with pressurized air (pressure 0.4-0.8 MPa) using a conventional spraying method. Place the UHPC specimen into a standard curing room for curing.

[0079] Comparative Example 2

[0080] This comparative example provides a method for preparing sprayed UHPC, which does not use magnesium chloride pre-wetting or add nano-aragonite. It utilizes high-temperature, high-pressure industrial waste gas containing carbon dioxide to perform carbon dioxide mineralization curing on conventional ultra-high performance concrete, including the following steps:

[0081] The sprayed ultra-high performance concrete base material was prepared according to steps S1-S2 of Comparative Example 1.

[0082] Industrial waste gas at 70℃ with a carbon dioxide concentration of 60 wt% was connected to an air compressor. The pumping equipment was started first, followed by the air compressor. The sprayed ultra-high performance concrete was pumped using industrial waste gas at a pressure of 0.4-0.8 MPa to obtain sprayed UHPC specimens, which were then cured.

[0083] Comparative Example 3

[0084] This comparative example provides a method for preparing sprayed UHPC without the addition of nano-aragonite. The porous aggregate is pretreated with magnesium chloride solution, and the ultra-high performance concrete is cured by carbon dioxide mineralization using high-temperature, high-pressure industrial waste gas containing carbon dioxide. The method includes the following steps:

[0085] Step S1: Weigh the following raw materials by weight: 350 parts cement, 60 parts fly ash cenospheres, 90 parts silica fume, 60 parts ultrafine limestone powder, 60 parts microfiber steel fiber, 100 parts mixing water, and 336 parts porous aggregate (zeolite).

[0086] Step S2: Soak the porous aggregate weighed in Step S1 in a 0.025 mol / L magnesium chloride solution for 24 hours, drain, and set aside to obtain pre-wetted porous aggregate. Then, mix the pre-wetted porous aggregate with the remaining raw materials from Step S1 to prepare sprayed ultra-high performance concrete. The specific mixing process is as follows:

[0087] 1) Thoroughly mix cement, fly ash cenospheres, silica fume, ultrafine limestone powder, and pre-wetted porous aggregate, and dry mix for 1-2 minutes;

[0088] 2) Add the mixing water and mix for 3-5 minutes;

[0089] 3) Add microfiber steel and continue stirring for 2-4 minutes to obtain sprayed ultra-high performance concrete base material.

[0090] Step S3: Connect industrial waste gas at 70℃ with a carbon dioxide concentration of 60vt% to an air compressor. First, turn on the pumping equipment, then turn on the air compressor. Use the industrial waste gas at a pressure of 0.4-0.8 MPa to pump the obtained sprayed ultra-high performance concrete base material to obtain sprayed UHPC specimens and cure them.

[0091] Performance testing

[0092] The UHPC specimens obtained in Examples 1-4 and Comparative Examples 1-3 were tested for compressive strength and flexural strength. The results are shown in Table 2 below.

[0093] Table 2 Compressive and flexural strength indices of UHPC spray test

[0094]

[0095] The test results in the table show that:

[0096] According to the embodiments 1-4 prepared according to the present invention, as can be seen from Table 2, the flexural strength of embodiments 1-4 can be increased by more than 25% and the compressive strength can be increased by more than 11% compared with comparative embodiment 1.

[0097] Compared with Comparative Example 1, Comparative Examples 2-3 and 1-4 all showed improved 3-day compressive strength, indicating that carbon dioxide injection can significantly improve the early strength of UHPC. Furthermore, compared with Comparative Examples 2 and 3, the 28-day compressive strength of Examples 1-4 was also improved, suggesting that the pre-adsorption of porous aggregate and the incorporation of nano-aragonite can further enhance the compressive strength of UHPC. These results indicate that carbon dioxide injection of UHPC + porous aggregate adsorbing magnesium chloride solution + nano-aragonite can significantly improve the compressive strength of UHPC, compensating for the compressive strength loss during the injection process.

[0098] Compared with Comparative Example 1, the flexural strength of Comparative Examples 2-3 and Examples 1-4 showed no significant change. However, the flexural strength of Comparative Example 2 was improved, while that of Comparative Example 3 and Examples 1-4 was increased. This indicates that carbon dioxide injection alone cannot generate calcium carbonate with a stable aragonite crystal structure. The magnesium chloride solution adsorbed by the porous aggregate stabilizes the aragonite generated by the carbon dioxide mineralization reaction, achieving multi-scale toughening and improving flexural strength. Compared with Comparative Example 3, Examples 1-4 showed a significant improvement in flexural strength, indicating that the addition of nano-aragonite as an inducer and toughening fiber accelerates aragonite formation and further improves flexural strength. Furthermore, the flexural strength of Example 4 was slightly higher than that of Examples 1-3, indicating that increasing the temperature can slightly improve the aragonite formation efficiency. These results demonstrate that carbon dioxide injection of UHPC + porous aggregate adsorbing magnesium chloride solution + nano-aragonite can significantly improve the flexural strength of UHPC, solving the problem of reduced tensile strength and toughness caused by the short steel fiber length and low steel fiber content in injection-sprayed UHPC.

[0099] Although some preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0100] Those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this application and their equivalents, this invention is also intended to include these modifications and variations.

Claims

1. A method for preparing multi-scale fiber-toughened sprayed UHPC using a carbon mineralization reaction, characterized in that, Includes the following steps: Step S1: Weigh the following raw materials by weight: 300-400 parts cement, 40-100 parts fly ash cenospheres, 50-100 parts silica fume, 40-70 parts ultrafine limestone powder, 30-70 parts microfiber steel fibers, 90-120 parts mixing water, 5-20 parts nano-aragonite, and 300-400 parts porous aggregate. The porous aggregate is zeolite and / or pumice with a particle size in the range of 0.45mm to 0.90mm and a water absorption rate in the range of 30% to 50%; the microfiber steel fiber has an aspect ratio of 50 to 70 and a diameter of 0.2 to 0.3mm; the nano-aragonite has an aspect ratio of 10 to 15 and a diameter of 40 to 60nm. Step S2: Soak the porous aggregate weighed in Step S1 in a magnesium chloride solution with a concentration of 0.025mol / L-0.05mol / L to fully absorb the magnesium chloride solution. After draining, the pre-wetted porous aggregate is obtained. The pre-wetted porous aggregate, along with the cement, fly ash cenospheres, silica fume, ultrafine limestone powder, microfiber steel fiber, mixing water, and nano-aragonite weighed in Step S1, are mixed to prepare sprayed ultra-high performance concrete. Step S3: Using industrial waste gas with a temperature of 60℃~80℃ and a carbon dioxide concentration of 50~70 vt%, the sprayed ultra-high performance concrete obtained in step S2 is pumped at a gas pressure of 0.4~0.8Mpa to obtain sprayed UHPC specimens and then cured.

2. The method for preparing multi-scale fiber-toughened sprayed UHPC using carbon mineralization reaction as described in claim 1, characterized in that, In step S1, the cement is silicate cement with a strength of not less than 42.5; the fly ash cenospheres have an average particle size of 1~5μm and a specific surface area greater than 2500m². 2 / kg.

3. The method for preparing multi-scale fiber-toughened sprayed UHPC using carbon mineralization reaction as described in claim 1, characterized in that, In step S1, the silica fume has a SiO2 content greater than 90% and a specific surface area greater than 20,000 m². 2 / kg; the CaCO3 content of the ultrafine limestone powder is greater than 95%, and the average particle size is not greater than 80nm.

4. The method for preparing multi-scale fiber-toughened sprayed UHPC using carbon mineralization reaction as described in claim 1, characterized in that, In step S2, the mixing preparation specifically includes: 1) Thoroughly mix cement, fly ash cenospheres, silica fume, ultrafine limestone powder, pre-wetted porous aggregate, and nano-aragonite, and dry mix for 1-2 minutes; 2) Add the mixing water and mix for 3-5 minutes; 3) Add microfiber steel and continue stirring for 2-4 minutes to obtain sprayed ultra-high performance concrete.

5. The method for preparing multi-scale fiber-toughened sprayed UHPC using carbon mineralization reaction as described in claim 1, characterized in that, In step S3, industrial waste gas with a temperature of 70~80℃ and a carbon dioxide concentration of 60 vt% is used.

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