High-temperature-resistant sprayable super high performance inorganic composite material and preparation method thereof

Abstract

The application provides a high-temperature-resistant sprayable super-high-performance inorganic composite material and a preparation method thereof, and belongs to the technical field of composite materials.The application comprises the following raw materials in parts by mass: 70-75 parts of P.II 52.5 silicate cement, 15-20 parts of silica fume, 10-15 parts of fly ash, 55-65 parts of first quartz sand, 20-25 parts of second quartz sand, 5-12 parts of quartz powder, 12-18 parts of steel fiber, 2-4 parts of water reducing agent, 0-7.5 parts of polypropylene fiber and 15-25 parts of water.The sprayable high-temperature-resistant super-high-performance concrete is beneficial to tunnel, bridge, pipe gallery and other accident-prone or closed emergency projects, promotes the development of super-high-performance concrete and speeds up the construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, specifically to a high-temperature resistant, sprayable, ultra-high performance inorganic composite material and its preparation method. Background Technology

[0002] Ultra-high performance concrete (UHPC) is a cement-based composite material constructed from silica fume, cement, fine aggregate, and steel fibers according to the principle of maximum compaction. It boasts outstanding advantages such as ultra-high mechanical properties (high strength, high elastic modulus, low creep), ultra-high durability, and superior impermeability, making it the most advanced cement-based composite material in the world today. It has already been applied in building and bridge structures. However, due to its high density resulting from the principle of maximum compaction, UHPC cannot fully release internal thermal stress under high temperatures, making it prone to thermal stress impact on the UHPC cementitious system, leading to thermal damage and cracking. This is particularly problematic in the relatively enclosed environment of tunnels, where rapid temperature rise and extreme ambient temperatures are common during fires. Currently, a common method to improve the high-temperature resistance of UHPC is to add large amounts of polypropylene fibers. While this method effectively provides high-temperature protection, the polypropylene fibers significantly affect the fluidity of UHPC, hindering self-compactment during casting and resulting in voids, thus impacting construction efficiency.

[0003] Therefore, there is an urgent need to find material composition design and preparation methods that are fast to construct and have excellent high temperature resistance. Summary of the Invention

[0004] To address the shortcomings and defects of existing technologies, this invention proposes a high-temperature resistant, sprayable, ultra-high performance inorganic composite material and its preparation method.

[0005] The technical solution of this invention is implemented as follows:

[0006] This invention provides a high-temperature resistant, sprayable, ultra-high performance inorganic composite material, comprising the following raw materials in parts by weight: 70-75 parts of P.II 52.5 silicate cement, 15-20 parts of silica fume, 10-15 parts of fly ash, 55-65 parts of first quartz sand, 20-25 parts of second quartz sand, 5-12 parts of quartz powder, 12-18 parts of steel fiber, 2-4 parts of water-reducing agent, 0-7.5 parts of polypropylene fiber, and 15-25 parts of water.

[0007] As a further improvement of the present invention, the raw materials include the following parts by weight: 73 parts of P.II 52.5 silicate cement, 18 parts of silica fume, 13 parts of fly ash, 60 parts of first quartz sand, 22.5 parts of second quartz sand, 9 parts of quartz powder, 16 parts of steel fiber, 2.5 parts of water-reducing agent, 5 parts of polypropylene fiber, and 20 parts of water.

[0008] As a further improvement of the present invention, the P.II 52.5 silicate cement has a particle size range of 0.28μm-120μm and a specific surface area of ​​375-380m² / kg.

[0009] Preferably, the P.II 52.5 silicate cement in the material has a particle size range of 0.28μm-120μm and a specific surface area of ​​379.4m² / kg.

[0010] As a further improvement of the present invention, the silica fume has a particle size range of 0.28μm-90μm and a specific surface area of ​​250-260m². 2 / kg; the particle size of the fly ash ranges from 0.28μm to 190μm, and the specific surface area is 410-420m². 2 / kg.

[0011] Preferably, the silica fume in the material has a particle size range of 0.28μm-90μm and a specific surface area of ​​255.3m² / kg; the fly ash in the material has a particle size range of 0.28μm-190μm and a specific surface area of ​​414.3m² / kg.

[0012] As a further improvement of the present invention, the particle size of the first quartz sand is in the range of 1μm-800μm, and the specific surface area is 30-35m². 2 / kg; the particle size range of the second quartz sand is 1.2μm-800μm, and the specific surface area is 32-37m². 2 / kg.

[0013] Preferably, the first quartz sand (model: 20-60) in the material has a particle size range of 1μm-800μm and a specific surface area of ​​32.98m² / kg; the second quartz sand (model: 60-120) in the material has a particle size range of 1.2μm-800μm and a specific surface area of ​​34.19m² / kg.

[0014] As a further improvement of the present invention, the quartz powder has a particle size range of 0.3μm-110μm and a specific surface area of ​​437.6m² / kg.

[0015] Preferably, the quartz powder in the material has a particle size range of 0.3μm-110μm and a specific surface area of ​​437.6m² / kg.

[0016] As a further improvement of the present invention, the steel fiber has a diameter of 0.1-0.3 mm, a length of 8-10 mm, and a tensile strength greater than 2800 MPa, and the polypropylene fiber has a length of 5-10 mm.

[0017] Preferably, the steel fiber has a diameter of 0.2 mm, a length of 9 mm, and a tensile strength greater than 2800 MPa. The polypropylene fiber has a length of 7 mm.

[0018] As a further improvement of the present invention, the high-temperature resistant ultra-high performance inorganic composite premix has a particle size range of 0.28μm-800μm and a specific surface area of ​​210-220m² / kg.

[0019] Preferably, the high-temperature resistant ultra-high performance inorganic composite premix has a particle size range of 0.28μm-800μm and a specific surface area of ​​216.7m² / kg.

[0020] This invention further protects a method for preparing the above-mentioned high-temperature resistant, sprayable, ultra-high performance inorganic composite material, comprising the following steps:

[0021] Step 1, Preparation of ultra-high performance inorganic composite premix:

[0022] Weigh out each component of P.II 52.5 silicate cement, silica fume, fly ash, quartz sand, quartz powder, water-reducing agent, and steel fiber according to their respective mass parts, and pour them into the mixer in sequence. Mix at low speed to form an ultra-high performance inorganic composite premix.

[0023] Step 2: Polypropylene fibers are incorporated into ultra-high performance inorganic composite premixes:

[0024] Weigh out polypropylene fibers according to the mass fraction, pour them into the ultra-high performance inorganic composite premix in batches and stir at low speed with a mixer at the same time to form a high temperature resistant ultra-high performance inorganic composite premix.

[0025] Step 3: Mix the high-temperature resistant, ultra-high-performance inorganic composite premix with water.

[0026] Weigh out the specified mass of high-temperature resistant ultra-high performance inorganic composite premix and pour it into the mixer. First, stir at low speed until it is evenly mixed. Then, add the specified mass of water and stir at high speed.

[0027] Step 4: Spray high-temperature resistant ultra-high performance concrete. After spraying, perform surface finishing and curing of the sprayed high-temperature resistant ultra-high performance concrete.

[0028] According to the technical specifications for the application of shotcrete (JCJ / T 372-216), high-temperature resistant ultra-high performance concrete is shotcreted. Based on the relationship between polypropylene fiber content and construction time, the following formula can be obtained:

[0029] ;

[0030] In the formula: T Time (s) required to fully spray a 450mm×450mm×120mm spray panel; x Polypropylene content (%);

[0031] ;

[0032] In the formula: V The volume (m³) of the sprayed large plate is 450mm×450mm×120mm; Q The jet flow rate is (m³ / s).

[0033] The injection flow rate Q (m³ / s) is proportional to the injection pressure P (kPa) and the polypropylene dosage. Specific parameters depend on the injection equipment. The relationship between injection pressure and injection flow rate is as follows:

[0034] ;

[0035] Obtain injection pressure p and polypropylene content x The relationship is as follows:

[0036] .

[0037] As a further improvement of the present invention, the speed of the low-speed stirring is 50-150 r / min, and the speed of the high-speed stirring is 800-1000 r / min.

[0038] The present invention has the following beneficial effects:

[0039] The high-temperature resistant, sprayable, ultra-high performance inorganic composite material provided by this invention adjusts the material ratio and regulates the working performance and internal structural porosity of UHPC based on the existing basic raw materials. While ensuring the original ultra-high performance of UHPC, the additional blending of steel fibers and polypropylene fibers improves the high-temperature resistance of the UHPC ultra-high performance inorganic composite material, improves the residual properties of high-temperature UHPC, and significantly reduces the risk of high-temperature cracking.

[0040] The high-temperature resistant, sprayable ultra-high performance inorganic composite material provided by this invention significantly improves the high-temperature resistance of concrete by incorporating polypropylene fibers, which melt at high temperatures to form thermal stress storage channels. Furthermore, the rapid concrete forming process using spraying increases the self-air-entraining capacity of the concrete during forming, thereby improving the internal porosity of the sprayed ultra-high performance concrete, resulting in superior high-temperature resistance compared to traditional high-density UHPC. Finally, spraying high-temperature resistant ultra-high performance concrete is beneficial for emergency projects involving frequent accidents or closures, such as tunnels, bridges, and utility tunnels, promoting the development of ultra-high performance concrete and accelerating construction efficiency. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a test diagram of preferred injection parameters and injection time according to the present invention;

[0043] Figure 2 The figures show the test results of the room temperature compressive strength of high-temperature resistant sprayable ultra-high performance concrete in preferred embodiments 1-4 of the present invention.

[0044] Figure 3 The figures show the test results of the room temperature compressive strength of high-temperature resistant sprayable ultra-high performance concrete in preferred comparative examples 1-2 of the present invention.

[0045] Figure 4 The figures show the residual strength test results of high-temperature resistant sprayable ultra-high performance concrete at the end of high-temperature tests in preferred embodiments 1-4 and comparative example 1 of the present invention.

[0046] Figure 5 These are the appearance diagrams of the completed high-temperature tests of preferred comparative examples 1 and 2 of the present invention;

[0047] Figure 6 This is a preferred comparative example 1 of the present invention, showing the appearance after a high-temperature test.

[0048] Figure 7 The images shown are of the finished high-temperature test results of a preferred embodiment 1-4 of the present invention. Detailed Implementation

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] In the following examples and comparative examples, unless otherwise specified, the particle size range of P.II 52.5 silicate cement is 0.28μm-120μm, with a specific surface area of ​​379.4m² / kg. The particle size range of silica fume is 0.28μm-90μm, with a specific surface area of ​​255.3m² / kg. The particle size range of fly ash is 0.28μm-190μm, with a specific surface area of ​​414.3m² / kg. The particle size range of silica sand (grade: 20-60) is 1μm-800μm, with a specific surface area of ​​32.98m² / kg. The particle size range of silica sand (grade: 60-120) is 1.2μm-800μm, with a specific surface area of ​​34.19m² / kg. The particle size range of silica powder is 0.3μm-110μm, with a specific surface area of ​​437.6m² / kg. The steel fibers have a diameter of 0.2 mm, a length of 9 mm, and a tensile strength greater than 2800 MPa. The polypropylene fibers have a length of 7 mm.

[0051] The composition of cement materials is shown in Table 1.

[0052] Table 1

[0053] Material <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO <![CDATA[Fe2O3]]> CaO quality loss cement 22.34 5.36 1.52 4.25 64.47 3.87 silica ash 94.72 0.12 0.65 0.22 1.23 1.83 fly ash 53.56 23.00 1.09 3.14 5.60 3.10

[0054] The spraying parameters are selected based on the polypropylene fiber content:

[0055] ;

[0056] Preferably, for a polypropylene fiber content of 0 parts, the spraying pressure during spraying is 0.808 MPa; for a polypropylene fiber content of 0.9 parts, the spraying pressure is 0.836 MPa; for a polypropylene fiber content of 1.8 parts, the spraying pressure is 0.864 MPa; for a polypropylene fiber content of 4.5 parts, the spraying pressure is 0.969 MPa; and for a polypropylene fiber content of 7.2 parts, the spraying pressure is 1.096 MPa.

[0057] Example 1

[0058] First, weigh out 73 parts of P.II 52.5 silicate cement, 31 parts of silica fume and fly ash, 60 parts of quartz sand (grade: 20-60), 22.5 parts of quartz sand (grade: 60-120), 9 parts of quartz powder, 2.5 parts of water-reducing agent, and 16 parts of steel fiber. Add each component sequentially to a mixer and mix at low speed for 20 seconds at a speed of 60 r / min to form an ultra-high performance inorganic composite premix.

[0059] Next, weigh 0.9 parts of polypropylene fiber according to the mass fraction, and add 0.1 parts of polypropylene fiber to the ultra-high performance inorganic composite premix in sequence. At the same time, stir each batch at low speed for 10 seconds to finally form a high temperature resistant ultra-high performance inorganic composite premix.

[0060] Move the wet spraying equipment (air compressor, wet sprayer, mixer, plastic hose, nozzle) to the construction area and select a suitable location for installation according to the site conditions. The spraying air pressure is 0.8-0.85MPa, the pumping wet sprayer power is 25kW, and the material conveying hose is 10m long.

[0061] Pour the above-mentioned high-temperature resistant ultra-high performance inorganic composite premix into a mixer and stir at a high speed of 120 r / min, while adding 20 parts of water.

[0062] High-temperature resistant ultra-high performance concrete was sprayed in accordance with the technical specifications for the application of shotcrete JCJ / T 372-216, forming a large shotcrete slab of 450mm×450mm×120mm.

[0063] Finally, the surface was finished with high-temperature resistant ultra-high-performance concrete and allowed to cure naturally. After 7 days of curing, the sample was cut, and after 28 days of curing, the final test specimen was formed.

[0064] Example 2

[0065] First, weigh out 73 parts of P.II 52.5 silicate cement, 31 parts of silica fume and fly ash, 60 parts of quartz sand (grade: 20-60), 22.5 parts of quartz sand (grade: 60-120), 9 parts of quartz powder, 2.5 parts of water-reducing agent, and 16 parts of steel fiber. Add each component sequentially to a mixer and mix at low speed for 20 seconds at a speed of 60 r / min to form an ultra-high performance inorganic composite premix.

[0066] Next, weigh 1.8 parts of polypropylene fiber according to the mass fraction, and add 0.2 parts of polypropylene fiber to the ultra-high performance inorganic composite premix in sequence. At the same time, stir each batch at low speed for 10 seconds to finally form a high temperature resistant ultra-high performance inorganic composite premix.

[0067] Move the wet spraying equipment (air compressor, wet sprayer, mixer, plastic hose, nozzle) to the construction area and select a suitable location for installation according to the site conditions. The spraying air pressure is 0.8-0.85MPa, the pumping wet sprayer power is 25kW, and the material conveying hose is 10m long.

[0068] Pour the above-mentioned high-temperature resistant ultra-high performance inorganic composite premix into a mixer and stir at a high speed of 120 r / min, while adding 20 parts of water.

[0069] High-temperature resistant ultra-high performance concrete was sprayed in accordance with the technical specifications for the application of shotcrete JCJ / T 372-216, forming a large shotcrete slab of 450mm×450mm×120mm.

[0070] Finally, the surface was finished with high-temperature resistant ultra-high-performance concrete and allowed to cure naturally. After 7 days of curing, the sample was cut, and after 28 days of curing, the final test specimen was formed.

[0071] Example 3

[0072] First, weigh out 73 parts of P.II 52.5 silicate cement, 31 parts of silica fume and fly ash, 60 parts of quartz sand (grade: 20-60), 22.5 parts of quartz sand (grade: 60-120), 9 parts of quartz powder, 2.5 parts of water-reducing agent, and 16 parts of steel fiber. Add each component sequentially to a mixer and mix at low speed for 20 seconds at a speed of 60 r / min to form an ultra-high performance inorganic composite premix.

[0073] Next, weigh 4.5 parts of polypropylene fiber according to the mass fraction, and pour 0.45 parts of polypropylene fiber into the ultra-high performance inorganic composite premix in sequence. At the same time, stir each batch at low speed for 10 seconds to finally form a high temperature resistant ultra-high performance inorganic composite premix.

[0074] Move the wet spraying equipment (air compressor, wet sprayer, mixer, plastic hose, nozzle) to the construction area and select a suitable location for installation according to the site conditions. The spraying air pressure is 0.8-0.85MPa, the pumping wet sprayer power is 25kW, and the material conveying hose is 10m long.

[0075] Pour the above-mentioned high-temperature resistant ultra-high performance inorganic composite premix into a mixer and stir at a high speed of 120 r / min, while adding 20 parts of water.

[0076] High-temperature resistant ultra-high performance concrete was sprayed in accordance with the technical specifications for the application of shotcrete JCJ / T 372-216, forming a large shotcrete slab of 450mm×450mm×120mm.

[0077] Finally, the surface was finished with high-temperature resistant ultra-high-performance concrete and allowed to cure naturally. After 7 days of curing, the sample was cut, and after 28 days of curing, the final test specimen was formed.

[0078] Example 4

[0079] First, weigh out 73 parts of P.II 52.5 silicate cement, 31 parts of silica fume and fly ash, 60 parts of quartz sand (grade: 20-60), 22.5 parts of quartz sand (grade: 60-120), 9 parts of quartz powder, 2.5 parts of water-reducing agent, and 16 parts of steel fiber. Add each component sequentially to a mixer and mix at low speed for 20 seconds at a speed of 60 r / min to form an ultra-high performance inorganic composite premix.

[0080] Next, weigh 7.2 parts of polypropylene fiber according to the mass fraction, and pour 0.72 parts of polypropylene fiber into the ultra-high performance inorganic composite premix in each batch. At the same time, stir each batch at low speed for 10 seconds to finally form a high temperature resistant ultra-high performance inorganic composite premix.

[0081] Move the wet spraying equipment (air compressor, wet sprayer, mixer, plastic hose, nozzle) to the construction area and select a suitable location for installation according to the site conditions. The spraying air pressure is 0.8-0.85MPa, the pumping wet sprayer power is 25kW, and the material conveying hose is 10m long.

[0082] Pour the above-mentioned high-temperature resistant ultra-high performance inorganic composite premix into a mixer and stir at a high speed of 120 r / min, while adding 20 parts of water.

[0083] High-temperature resistant ultra-high performance concrete was sprayed in accordance with the technical specifications for the application of shotcrete JCJ / T 372-216, forming a large shotcrete slab of 450mm×450mm×120mm.

[0084] Finally, the surface was finished with high-temperature resistant ultra-high-performance concrete and allowed to cure naturally. After 7 days of curing, the sample was cut, and after 28 days of curing, the final test specimen was formed.

[0085] Comparative Example 1

[0086] First, weigh out 73 parts of P.II 52.5 silicate cement, 31 parts of silica fume and fly ash, 60 parts of quartz sand (grade: 20-60), 22.5 parts of quartz sand (grade: 60-120), 9 parts of quartz powder, 2.5 parts of water-reducing agent, and 16 parts of steel fiber. Add each component sequentially to a mixer and mix at low speed for 20 seconds at a speed of 60 r / min to form an ultra-high performance inorganic composite premix.

[0087] Move the wet spraying equipment (air compressor, wet sprayer, mixer, plastic hose, nozzle) to the construction area and select a suitable location for installation according to the site conditions. The spraying air pressure is 0.8-0.85MPa, the pumping wet sprayer power is 25kW, and the material conveying hose is 10m long.

[0088] The above-mentioned ultra-high performance inorganic composite premix was poured into a mixer and stirred at a high speed of 120 r / min, while 20 parts of water were added at the same time.

[0089] High-temperature resistant ultra-high performance concrete was sprayed in accordance with the technical specifications for the application of shotcrete JCJ / T 372-216, forming a large shotcrete slab of 450mm×450mm×120mm.

[0090] Comparative Example 2

[0091] First, weigh out 73 parts of P.II 52.5 silicate cement, 31 parts of silica fume and fly ash, 60 parts of quartz sand (grade: 20-60), 22.5 parts of quartz sand (grade: 60-120), 9 parts of quartz powder, 2.5 parts of water-reducing agent, and 16 parts of steel fiber. Add each component sequentially to a mixer and mix at low speed for 20 seconds at a speed of 60 r / min to form an ultra-high performance inorganic composite premix.

[0092] The above-mentioned ultra-high performance inorganic composite premix was poured into a mixer and stirred at a high speed of 120 r / min, while 20 parts of water were added at the same time.

[0093] Finally, the freshly mixed ultra-high performance concrete was poured into the mold, vibrated, and left to stand for 1 day before demolding. During this period, it was covered with plastic film to prevent moisture evaporation. After demolding, it was naturally cured for 28 days to finally form the test specimen.

[0094] Experimental Example 1

[0095] The high-temperature resistant, sprayable, ultra-high performance inorganic composite materials obtained in Examples 1-4 and Comparative Examples 1-2 were subjected to the following performance tests, the specific procedures of which are as follows:

[0096] 1. Three 100mm×100mm×100mm specimens from Examples 1-4 and Comparative Examples 1-2, cured for 1 day, 7 days, and 28 days respectively, were directly subjected to compressive strength tests. The test results are as follows: Figure 1 and Figure 2 The cubic compressive strength was tested according to GB / T 50081-2016 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", with a loading rate of 12kN / s-14kN / s.

[0097] 2. Three 100mm×100mm×100mm specimens from Examples 1-4 and Comparative Examples 1-2, cured for 28 days, were subjected to high-temperature resistance tests. The target high-temperature temperatures were set at 300℃, 400℃, 500℃, 600℃, and 700℃, respectively. The high-temperature resistance tests were conducted according to YB / T 4252-2011 "Technical Specification for Application of Heat-Resistant Concrete," using an electric kiln for heating at a rate of 5℃ / min. The bursting test results are shown in Table 2.

[0098] 3. The samples from Examples 1-4 and Comparative Example 1 that did not crack after the high-temperature resistance test were subjected to residual strength testing. The residual strength test was conducted according to GB / T 50081-2016 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", with a loading rate of 12kN / s-14kN / s. The experimental results are shown in Table 2.

[0099] Table 2

[0100] serial number Temperature / °C Explosion situation Example 1 300℃、400℃、500℃、600℃、700℃ Unexploded Example 2 300℃、400℃、500℃、600℃、700℃ Unexploded Example 3 300℃、400℃、500℃、600℃、700℃ Unexploded Example 4 300℃、400℃、500℃、600℃、700℃ Unexploded Comparative Example 1 300℃、400℃、500℃ Unexploded Comparative Example 1 600℃ Explosion at 535℃ Comparative Example 2 500℃ Explosion at 495℃

[0101] Table 2 shows that the high-temperature resistant sprayable ultra-high performance concrete prepared in Examples 1-4 did not experience cracking at temperatures ranging from 300℃ to 700℃, demonstrating excellent high-temperature resistance. Comparative Examples 1-2 all experienced cracking at temperatures ranging from 300℃ to 600℃. Specifically, the cracking temperature of Comparative Example 1 was 535℃, and the cracking temperature of Comparative Example 2 was 495℃. This indicates that the spraying construction process can improve the high-temperature resistance of ultra-high performance concrete compared to the pouring process.

[0102] Figure 2 , Figure 3 The corresponding room temperature compressive strength test results are shown in Figures 1-4 and 1-2, respectively. Figure 4 High-temperature residual strength tests were conducted for Examples 1-5 and Comparative Example 1. Figure 5 The images shown are of Comparative Examples 1-2 after the temperature rise to 500℃. Figure 6 The images are of Comparative Example 1 after the temperature rise to 535℃ and at room temperature. Figure 7 The images shown are of the finished products of Examples 1-4 after heating to 700°C.

[0103] Depend on Figure 2 , Figure 3 The material strength of ultra-high performance concrete prepared using the spraying process is all above 100 MPa, which meets the definition of ultra-high performance concrete. The polypropylene fiber content affects the spraying of UHPC; the closer the spraying air pressure is to the optimal air pressure for different polypropylene contents, the higher the performance indicators of the high-temperature resistant sprayable ultra-high performance inorganic composite material.

[0104] Depend on Figure 4 It can be seen that, compared with Comparative Example 1, Examples 1-4 show a significant trend of increased residual strength after the high-temperature test, while the strength of Comparative Example 1 remains basically unchanged or decreases slightly after the high-temperature test. The residual strength of Examples 1-4 begins to decrease at 700℃, but the residual strength / compressive strength ratio of Examples 1-4 at 700℃ is still much greater than 1, indicating that Examples 1-4 have extremely strong residual properties after high temperature.

[0105] Depend on Figure 5 , Figure 6 and Figure 7 It can be seen that for Examples 1-4, which are mixed with polypropylene fibers, the surface turned yellow after the high-temperature test, but no cracking occurred. The surface of Comparative Example 1, which uses a spray molding process with only steel fibers, turned black after the high-temperature test. Although its high-temperature resistance was improved compared to the casting process with only steel fibers, it did not provide high-temperature protection. Examples 1-4 only showed high-temperature thermal stress cracks on the surface during the entire high-temperature test.

[0106] In summary, this invention provides a high-temperature resistant, ultra-high-performance inorganic material prepared by a spraying process using a blend of polypropylene fibers and steel fibers. This material exhibits excellent high-temperature resistance. Based on different polypropylene content, an optimal spraying pressure is proposed to achieve sprayable high-temperature resistant, ultra-high-performance inorganic composite materials.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-temperature resistant, sprayable, ultra-high performance inorganic composite material, characterized in that, include: Step 1, Preparation of ultra-high performance inorganic composite premix: Weigh out each component of P.II 52.5 silicate cement, silica fume, fly ash, quartz sand, quartz powder, water-reducing agent, and steel fiber according to their respective mass parts, and pour them into the mixer in sequence. Mix at low speed to form an ultra-high performance inorganic composite premix. Step 2: Polypropylene fibers are incorporated into ultra-high performance inorganic composite premixes: Weigh out polypropylene fibers according to the mass fraction, pour them into the ultra-high performance inorganic composite premix in batches and stir at low speed with a mixer at the same time to form a high temperature resistant ultra-high performance inorganic composite premix. Step 3: Mix the high-temperature resistant, ultra-high-performance inorganic composite premix with water. Weigh out the specified mass of high-temperature resistant ultra-high performance inorganic composite premix and pour it into the mixer. First, stir at low speed until it is evenly mixed. Then, add the specified mass of water and stir at high speed. Step 4: Spray high-temperature resistant ultra-high performance concrete. After spraying, perform surface finishing and curing of the sprayed high-temperature resistant ultra-high performance concrete. According to the JCJ / T 372-2016 Technical Specification for Application of Shotcrete, high-temperature resistant ultra-high performance concrete is shotcreted. Based on the relationship between polypropylene fiber content and construction time, the following formula can be obtained: ； In the formula: T Time (s) required to fully spray a 450mm×450mm×120mm spray plate; x Polypropylene content (%); ； In the formula: V The volume (m³) of the sprayed large plate is 450mm×450mm×120mm; Q The jet flow rate is (m³ / s). The injection flow rate Q (m³ / s) is proportional to the injection pressure P (kPa) and the polypropylene dosage. Specific empirical parameters depend on the values ​​of the injection equipment. The relationship between injection pressure and injection flow rate is as follows: ； Obtain injection pressure p and polypropylene content x The relationship is as follows: 。 2. The method for preparing high-temperature resistant, sprayable, ultra-high performance inorganic composite material according to claim 1, characterized in that, The raw materials include the following parts by weight: 70-75 parts of P.II 52.5 silicate cement, 15-20 parts of silica fume, 10-15 parts of fly ash, 55-65 parts of first-grade quartz sand, 20-25 parts of second-grade quartz sand, 5-12 parts of quartz powder, 12-18 parts of steel fiber, 2-4 parts of water-reducing agent, 0-7.5 parts of polypropylene fiber, and 15-25 parts of water.

3. The method for preparing high-temperature resistant, sprayable, ultra-high performance inorganic composite material according to claim 1, characterized in that, The raw materials include the following parts by weight: 73 parts of P.II 52.5 silicate cement, 18 parts of silica fume, 13 parts of fly ash, 60 parts of first-grade quartz sand, 22.5 parts of second-grade quartz sand, 9 parts of quartz powder, 16 parts of steel fiber, 2.5 parts of water-reducing agent, 5 parts of polypropylene fiber, and 20 parts of water.

4. The method for preparing high-temperature resistant, sprayable, ultra-high performance inorganic composite material according to claim 1, characterized in that, The P.II 52.5 silicate cement has a particle size range of 0.28μm-120μm and a specific surface area of ​​375-380m² / kg.

5. The method for preparing high-temperature resistant, sprayable, ultra-high performance inorganic composite material according to claim 1, characterized in that, The silica fume has a particle size range of 0.28μm-90μm and a specific surface area of ​​250-260m². 2 / kg; the fly ash particle size range is 0.28μm-190μm, and the specific surface area is 410-420m². 2 / kg.

6. The method for preparing high-temperature resistant, sprayable, ultra-high performance inorganic composite material according to claim 2, characterized in that, The first type of quartz sand has a particle size range of 1μm-800μm and a specific surface area of ​​30-35m². 2 / kg; the particle size range of the second quartz sand is 1.2μm-800μm, and the specific surface area is 32-37m². 2 / kg.

7. The method for preparing high-temperature resistant, sprayable, ultra-high performance inorganic composite material according to claim 1, characterized in that, The quartz powder has a particle size range of 0.3μm-110μm and a specific surface area of ​​437.6m² / kg.

8. The method for preparing high-temperature resistant, sprayable, ultra-high performance inorganic composite material according to claim 1, characterized in that, The steel fibers have a diameter of 0.1-0.3 mm, a length of 8-10 mm, and a tensile strength greater than 2800 MPa. The polypropylene fibers have a length of 5-10 mm.

9. The method for preparing high-temperature resistant, sprayable, ultra-high performance inorganic composite material according to claim 1, characterized in that, The high-temperature resistant, ultra-high-performance inorganic composite premix has a particle size range of 0.28μm-800μm and a specific surface area of ​​210-220m² / kg.

10. The method for preparing high-temperature resistant, sprayable, ultra-high performance inorganic composite material according to claim 1, characterized in that, The low-speed stirring speed is 50-150 r / min, and the high-speed stirring speed is 800-1000 r / min.

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