Sprayable ultra-high performance concrete for alpine regions and methods of making and using the same

Abstract

The application relates to the technical field of ultra-high performance concrete, and particularly discloses a sprayable ultra-high performance concrete for high-cold regions, which is prepared from raw materials including premix and activated glass fiber, and the mass ratio of the premix and the activated glass fiber is 220-300:6-12; the raw materials of the premix include, by mass fraction, cement 70-80 parts, silica flour 10-20 parts, fly ash 5-15 parts, coarse sand 70-75 parts, fine sand 33-39 parts, ultra-fine composite powder 10-15 parts, water reducing agent 4-6 parts, quick-setting agent 4-8 parts, microcrystalline cellulose 5-10 parts, methyl methacrylate 1-2 parts, cerium ammonium nitrate 0.01-0.1 part, ethylenediamine 1-2 parts, methyl acrylate 1-2 parts, steel fiber 3-7 parts, graphene oxide 1-2 parts and water 13-17 parts; the activated glass fiber is obtained by treating glass fiber with lye, adding the glass fiber and siloxane into an ethanol aqueous solution and performing heat treatment.

Description

A sprayable ultra-high performance concrete for high-altitude and cold regions, and its preparation and application methods. Technical Field

[0001] This invention relates to the field of ultra-high performance concrete technology, and in particular to a sprayable ultra-high performance concrete for high-altitude and cold regions, and its preparation and application methods. Background Technology

[0002] Ultra-high performance concrete has excellent mechanical properties and durability, especially its resistance to bending, low water absorption, high surface density, and stain resistance. It currently has promising application prospects in national defense engineering, marine engineering, nuclear industry, special security and protection engineering, and municipal engineering.

[0003] Given the numerous advantages of ultra-high performance concrete, its application scenarios are becoming increasingly widespread.

[0004] With increasingly complex architectural designs, direct casting is no longer feasible. Therefore, there is an urgent need to develop sprayable concrete material systems. However, sprayable ultra-high performance concrete suffers from drawbacks such as poor compressive strength, poor toughness, and insufficient water permeability resistance. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a sprayable ultra-high performance concrete for high-altitude and cold regions, as well as its preparation and application methods.

[0006] A type of ultra-high performance concrete that can be sprayed in cold regions, the raw materials of which include: premix and activated glass fiber, the mass ratio of premix and activated glass fiber is 220-300:6-12.

[0007] The raw materials of the premixed material, by weight, include: 70-80 parts cement, 10-20 parts silica fume, 5-15 parts fly ash, 70-75 parts coarse sand, 33-39 parts fine sand, 10-15 parts ultrafine composite powder, 4-6 parts water-reducing agent, 4-8 parts quick-setting agent, 5-10 parts microcrystalline cellulose, 1-2 parts methyl methacrylate, 0.01-0.1 parts cerium ammonium nitrate, 1-2 parts ethylenediamine, 1-2 parts methyl acrylate, 3-7 parts steel fiber, 1-2 parts graphene oxide, and 13-17 parts water.

[0008] Activated glass fiber is obtained by treating glass fiber with an alkaline solution, then adding it together with siloxane into an aqueous ethanol solution and heating it.

[0009] Preferably, the cement is PO42.5 silicate cement.

[0010] Preferably, the coarse sand is 16-26 mesh manufactured sand, the fine sand is 26-40 mesh quartz sand, and the ultrafine composite powder is 40-80 mesh.

[0011] Preferably, the ultrafine composite powder is fluorite ore waste sand and / or copper slag.

[0012] Preferably, the activated glass fiber is prepared by the following specific operation: the glass fiber is added to an aqueous sodium hydroxide solution and ultrasonically treated for 5-15 minutes, filtered, washed, and vacuum dried, and then added to an aqueous ethanol solution with aminopropyltriethoxysilane, stirred at 80-90°C for 1-2 hours, filtered, washed, and vacuum dried.

[0013] Preferably, the mass ratio of glass fiber to aminopropyltriethoxysilane is 5-10:1-2.

[0014] Preferably, the concentration of the sodium hydroxide aqueous solution is 0.5-1.2 mol / L, and the mass fraction of the ethanol aqueous solution is 40-60%.

[0015] The preparation method of the above-mentioned ultra-high performance concrete that can be sprayed in high-altitude and cold regions includes the following steps:

[0016] S1. Mix cement, silica fume, coarse sand, fine sand, ultrafine composite powder, water-reducing agent, and quick-setting agent evenly to obtain a cementitious material;

[0017] S2. Add microcrystalline cellulose to methanol and stir evenly. Under nitrogen protection, add methyl methacrylate and stir evenly. Add cerium ammonium nitrate and stir at 30-50℃ for 1-2 hours. Add ethylenediamine and stir at 50-60℃ for 5-15 hours. Add methyl acrylate and continue stirring for 10-20 hours. Cool to room temperature, add water, centrifuge, wash, and vacuum dry to obtain activated cellulose.

[0018] S3. Add steel fibers, graphene oxide, activated cellulose and water to the cementitious material and mix evenly to obtain a premix; mix the premix with activated glass fibers and spray.

[0019] The above-mentioned method for using ultra-high performance concrete in high-altitude and cold regions involves adding premixed material to a mortar spraying machine for spraying, while activated glass fiber is mixed with the premixed material and sprayed at the nozzle of the mortar spraying machine.

[0020] Preferably, the operating parameters of the mortar spraying machine are as follows: conveying pressure of 2.5-4.2 MPa and conveying flow rate of 1-3 m³ / h. 3 The spraying speed is 1-1.6m, and the spraying thickness is controlled at 5-15mm per layer.

[0021] Beneficial effects:

[0022] 1. This invention uses activated cellulose to enhance the anti-sagging properties of mortar, combined with activated glass fiber. The two are bonded together by hydrogen bonds, which binds concrete cement with ultrafine composite powder, silica fume, fine sand and coarse sand together, improving the cohesiveness and filling properties of the mortar and solving the problem of uneven dispersion of sprayed mortar.

[0023] 2. This invention grafts dendritic macromolecules onto the surface of microcrystalline cellulose, resulting in a product surface rich in amino groups. Combined with activated glass fibers, this is added to the system in steps, giving ultra-high performance concrete excellent workability. It not only improves early hydration reaction and significantly increases early strength compared to ordinary concrete, but also exhibits good water permeability resistance when combined with graphene oxide. Furthermore, the setting time is adjustable. The two-dimensional plane of graphene oxide has numerous functionalizable binding sites, which, when combined with activated cellulose, increase system stability and form intermolecular hydrogen bonds with water molecules, inhibiting water crystallization and effectively lowering the freezing point. This makes it particularly suitable for use in cold regions.

[0024] 3. This invention effectively avoids layered spraying, and the surface of the contact surface with the mold is free of exposed fibers, further improving production efficiency. It can be sprayed, has good fluidity and post-spray thixotropy, does not drip, and is suitable for various spraying equipment, with broad application prospects.

[0025] 4. The preparation process of this invention is simple, ensuring that sprayed concrete can be successfully constructed in low-temperature environments, while effectively shortening the construction period, improving social and economic benefits, and making it suitable for large-scale promotion and application. Attached Figure Description

[0026] Figure 1 is a comparison of the flowability and 28-day flexural strength of the concrete obtained in Example 5 and Comparative Examples 1-2.

[0027] Figure 2 shows the change in compressive strength and curing time of the concrete obtained in Example 5 and Comparative Examples 1-2. Detailed Implementation

[0028] The present invention will be further explained below with reference to specific embodiments.

[0029] The alkali-free liquid quick-setting agent and polycarboxylate superplasticizer used below were purchased from Jiangsu XX New Materials Co., Ltd. The quick-setting agent model is SL15 and the polycarboxylate superplasticizer model is M171.

[0030] Example 1

[0031] A type of ultra-high performance concrete that can be sprayed in high-altitude and cold regions, the raw materials of which include: premix and activated glass fiber, the mass ratio of premix to activated glass fiber is 227.41:6.

[0032] The raw materials for the premix include: 70 kg of PO42.5 silicate cement, 10 kg of silica fume, 5 kg of fly ash, 70 kg of 16-26 mesh manufactured sand, 33 kg of 26-40 mesh quartz sand, 10 kg of 40-80 mesh fluorite ore waste sand, 0.4 kg of polycarboxylate superplasticizer, 4 kg of alkali-free liquid quick-setting agent, 5 kg of microcrystalline cellulose, 1 kg of methyl methacrylate, 0.01 kg of cerium ammonium nitrate, 1 kg of ethylenediamine, 1 kg of methyl acrylate, 3 kg of steel fiber, 1 kg of graphene oxide, and 13 kg of water.

[0033] The activated glass fiber was prepared by the following specific operation: 5 kg of glass fiber was added to 30 kg of 0.5 mol / L sodium hydroxide aqueous solution and ultrasonically treated for 5 min at a frequency of 5 kHz. After filtration, washing, and vacuum drying, 1 kg of aminopropyltriethoxysilane was added to 30 kg of 40% ethanol aqueous solution and stirred at 80 °C for 1 h. After filtration, washing, and vacuum drying, the glass fiber was prepared.

[0034] The preparation method of the above-mentioned ultra-high performance concrete that can be sprayed in high-altitude and cold regions includes the following steps:

[0035] S1. Add cement, silica fume, manufactured sand, quartz sand, fluorite mine waste sand, water-reducing agent, and quick-setting agent to a mortar mixer and mix evenly to obtain a cementitious material;

[0036] S2. Microcrystalline cellulose was added to 20 kg of methanol and stirred evenly. Methyl methacrylate was added under nitrogen protection and stirred evenly. Cerium ammonium nitrate was added and stirred at 30°C for 1 h. Ethylenediamine was added and stirred at 50°C for 5 h. Methyl acrylate was added and stirred for another 10 h. The mixture was cooled to room temperature, 50 kg of water was added, and the mixture was centrifuged, washed, and vacuum dried to obtain activated cellulose.

[0037] S3. Add steel fibers, graphene oxide, activated cellulose and water to the cementitious material and mix evenly to obtain a premix; mix the premix with activated glass fibers and spray.

[0038] The above-mentioned method for using ultra-high performance concrete in high-altitude and cold regions involves adding premixed materials to a mortar spraying machine for spraying; while activated glass fibers are mixed with the premixed materials and sprayed at the nozzle of the mortar spraying machine.

[0039] The operating parameters of the mortar spraying machine are as follows: conveying pressure is 2.5MPa, and conveying flow rate is 1m³ / min. 3 / min, spraying distance is 1m, and spraying thickness is controlled at 5mm per layer.

[0040] Example 2

[0041] A high-performance sprayable concrete for cold regions is made from premixed materials and activated glass fibers, with a mass ratio of 294.9:12.

[0042] The raw materials for the premix include: 80 kg of PO42.5 silicate cement, 20 kg of silica fume, 15 kg of fly ash, 75 kg of 16-26 mesh manufactured sand, 39 kg of 26-40 mesh quartz sand, 15 kg of 40-80 mesh copper slag, 0.8 kg of polycarboxylate superplasticizer, 8 kg of alkali-free liquid quick-setting agent, 10 kg of microcrystalline cellulose, 2 kg of methyl methacrylate, 0.1 kg of cerium ammonium nitrate, 2 kg of ethylenediamine, 2 kg of methyl acrylate, 7 kg of steel fiber, 2 kg of graphene oxide, and 17 kg of water.

[0043] The activated glass fiber was prepared by the following specific operation: 10 kg of glass fiber was added to 50 kg of 1.2 mol / L sodium hydroxide aqueous solution and ultrasonically treated for 15 min at a frequency of 10 kHz. After filtration, washing, and vacuum drying, 2 kg of aminopropyltriethoxysilane was added to 50 kg of 60% ethanol aqueous solution and stirred at 90 °C for 2 h. After filtration, washing, and vacuum drying, the glass fiber was prepared.

[0044] The preparation method of the above-mentioned ultra-high performance concrete that can be sprayed in high-altitude and cold regions includes the following steps:

[0045] S1. Add cement, silica fume, manufactured sand, quartz sand, copper slag, water-reducing agent, and quick-setting agent to a mortar mixer and mix evenly to obtain a cementitious material;

[0046] S2. Microcrystalline cellulose was added to 40 kg of methanol and stirred evenly. Methyl methacrylate was added under nitrogen protection and stirred evenly. Cerium ammonium nitrate was added and stirred at 50°C for 2 h. Ethylenediamine was added and stirred at 60°C for 15 h. Methyl acrylate was added and stirred for another 20 h. The mixture was cooled to room temperature, 100 kg of water was added, and the mixture was centrifuged, washed, and vacuum dried to obtain activated cellulose.

[0047] S3. Add steel fibers, graphene oxide, activated cellulose and water to the cementitious material and mix evenly to obtain a premix; mix the premix with activated glass fibers and spray.

[0048] The above-mentioned method for using ultra-high performance concrete in high-altitude and cold regions involves adding premixed materials to a mortar spraying machine for spraying; while activated glass fibers are mixed with the premixed materials and sprayed at the nozzle of the mortar spraying machine.

[0049] The operating parameters of the mortar spraying machine are as follows: conveying pressure is 4.2 MPa, and conveying flow rate is 3 m³ / s. 3 The spraying speed is 1 / min, the spraying distance is 1.6m, and the spraying thickness is controlled at 15mm per layer.

[0050] Example 3

[0051] A type of ultra-high performance concrete that can be sprayed in cold regions, the raw materials of which include: premix and activated glass fiber, the mass ratio of premix to activated glass fiber is 261.63:7.8.

[0052] The raw materials for the premix include: 73 kg of PO42.5 silicate cement, 18 kg of silica fume, 8 kg of fly ash, 73 kg of 16-26 mesh manufactured sand, 35 kg of 26-40 mesh quartz sand, 10 kg of 40-80 mesh fluorite ore waste sand, 3 kg of 40-80 mesh copper slag, 0.5 kg of polycarboxylate superplasticizer, 7 kg of alkali-free liquid quick-setting agent, 6 kg of microcrystalline cellulose, 1.7 kg of methyl methacrylate, 0.03 kg of cerium ammonium nitrate, 1.8 kg of ethylenediamine, 1.3 kg of methyl acrylate, 6 kg of steel fiber, 1.3 kg of graphene oxide, and 16 kg of water.

[0053] The activated glass fiber was prepared by the following specific operation: 6 kg of glass fiber was added to 45 kg of 0.6 mol / L sodium hydroxide aqueous solution and ultrasonically treated for 12 min at a frequency of 7 kHz. After filtration, washing, and vacuum drying, 1.8 kg of aminopropyltriethoxysilane was added to 35 kg of 55% ethanol aqueous solution and stirred at 82℃ for 100 min. After filtration, washing, and vacuum drying, the activated glass fiber was prepared.

[0054] The preparation method of the above-mentioned ultra-high performance concrete that can be sprayed in high-altitude and cold regions includes the following steps:

[0055] S1. Add cement, silica fume, manufactured sand, quartz sand, fluorite mine waste sand, copper slag, water-reducing agent, and quick-setting agent to a mortar mixer and mix evenly to obtain a cementitious material.

[0056] S2. Microcrystalline cellulose was added to 25 kg of methanol and stirred evenly. Methyl methacrylate was added under nitrogen protection and stirred evenly. Cerium ammonium nitrate was added and stirred at 45℃ for 80 min. Ethylenediamine was added and stirred at 58℃ for 8 h. Methyl acrylate was added and stirring was continued for 18 h. The mixture was cooled to room temperature, 60 kg of water was added, and the mixture was centrifuged, washed, and vacuum dried to obtain activated cellulose.

[0057] S3. Add steel fibers, graphene oxide, activated cellulose and water to the cementitious material and mix evenly to obtain a premix; mix the premix with activated glass fibers and spray.

[0058] The above-mentioned method for using ultra-high performance concrete in high-altitude and cold regions involves adding premixed materials to a mortar spraying machine for spraying; while activated glass fibers are mixed with the premixed materials and sprayed at the nozzle of the mortar spraying machine.

[0059] The operating parameters of the mortar spraying machine are as follows: conveying pressure is 4MPa, and conveying flow rate is 2.5m³ / h. 3 The spraying speed is 1 / min, the spraying distance is 1.4m, and the spraying thickness is controlled at 12mm per layer.

[0060] Example 4

[0061] A type of ultra-high performance concrete that can be sprayed in cold regions, the raw materials of which include: premix and activated glass fiber, the mass ratio of premix to activated glass fiber is 257.67:9.2.

[0062] The raw materials for the premix include: 77 kg of PO42.5 silicate cement, 12 kg of silica fume, 12 kg of fly ash, 71 kg of 16-26 mesh manufactured sand, 37 kg of 26-40 mesh quartz sand, 2 kg of 40-80 mesh fluorite ore waste sand, 9 kg of 40-80 mesh copper slag, 0.7 kg of polycarboxylate superplasticizer, 5 kg of alkali-free liquid quick-setting agent, 8 kg of microcrystalline cellulose, 1.3 kg of methyl methacrylate, 0.07 kg of cerium ammonium nitrate, 1.2 kg of ethylenediamine, 1.7 kg of methyl acrylate, 4 kg of steel fiber, 1.7 kg of graphene oxide, and 14 kg of water.

[0063] The activated glass fiber was prepared by the following specific operation: 8 kg of glass fiber was added to 35 kg of 1 mol / L sodium hydroxide aqueous solution and ultrasonically treated for 8 min at a frequency of 9 kHz. After filtration, washing, and vacuum drying, 1.2 kg of aminopropyltriethoxysilane was added to 45 kg of 45% ethanol aqueous solution and stirred at 88℃ for 80 min. After filtration, washing, and vacuum drying, the activated glass fiber was prepared.

[0064] The preparation method of the above-mentioned ultra-high performance concrete that can be sprayed in high-altitude and cold regions includes the following steps:

[0065] S1. Add cement, silica fume, manufactured sand, quartz sand, fluorite mine waste sand, copper slag, water-reducing agent, and quick-setting agent to a mortar mixer and mix evenly to obtain a cementitious material.

[0066] S2. Microcrystalline cellulose was added to 35 kg of methanol and stirred evenly. Methyl methacrylate was added under nitrogen protection and stirred evenly. Cerium ammonium nitrate was added and stirred at 35°C for 100 min. Ethylenediamine was added and stirred at 52°C for 12 h. Methyl acrylate was added and stirred for another 12 h. The mixture was cooled to room temperature, 90 kg of water was added, and the mixture was centrifuged, washed, and vacuum dried to obtain activated cellulose.

[0067] S3. Add steel fibers, graphene oxide, activated cellulose and water to the cementitious material and mix evenly to obtain a premix; mix the premix with activated glass fibers and spray.

[0068] The above-mentioned method for using ultra-high performance concrete in high-altitude and cold regions involves adding premixed materials to a mortar spraying machine for spraying; while activated glass fibers are mixed with the premixed materials and sprayed at the nozzle of the mortar spraying machine.

[0069] The operating parameters of the mortar spraying machine are as follows: conveying pressure is 2.8 MPa, and conveying flow rate is 1.5 m³ / s. 3 The spraying speed is 1.2m, the spraying distance is 1.2m, and the spraying thickness is controlled at 8mm per layer.

[0070] Example 5

[0071] A type of ultra-high performance concrete that can be sprayed in cold regions, the raw materials of which include: premix and activated glass fiber, the mass ratio of premix to activated glass fiber is 259.65:8.5.

[0072] The raw materials for the premix include: 75 kg of PO42.5 silicate cement, 15 kg of silica fume, 10 kg of fly ash, 72 kg of 16-26 mesh manufactured sand, 36 kg of 26-40 mesh quartz sand, 6 kg of 40-80 mesh fluorite ore waste sand, 6 kg of 40-80 mesh copper slag, 0.6 kg of polycarboxylate superplasticizer, 6 kg of alkali-free liquid quick-setting agent, 7 kg of microcrystalline cellulose, 1.5 kg of methyl methacrylate, 0.05 kg of cerium ammonium nitrate, 1.5 kg of ethylenediamine, 1.5 kg of methyl acrylate, 5 kg of steel fiber, 1.5 kg of graphene oxide, and 15 kg of water.

[0073] The activated glass fiber was prepared by the following specific operation: 7 kg of glass fiber was added to 40 kg of 0.8 mol / L sodium hydroxide aqueous solution and ultrasonically treated for 10 min at an ultrasonic frequency of 8 kHz. After filtration, washing, and vacuum drying, 1.5 kg of aminopropyltriethoxysilane was added to 40 kg of 50% ethanol aqueous solution and stirred at 85℃ for 90 min. After filtration, washing, and vacuum drying, the glass fiber was prepared.

[0074] The preparation method of the above-mentioned ultra-high performance concrete that can be sprayed in high-altitude and cold regions includes the following steps:

[0075] S1. Add cement, silica fume, manufactured sand, quartz sand, fluorite mine waste sand, copper slag, water-reducing agent, and quick-setting agent to a mortar mixer and mix evenly to obtain a cementitious material.

[0076] S2. Microcrystalline cellulose was added to 30 kg of methanol and stirred evenly. Methyl methacrylate was added under nitrogen protection and stirred evenly. Cerium ammonium nitrate was added and stirred at 40℃ for 90 min. Ethylenediamine was added and stirred at 55℃ for 10 h. Methyl acrylate was added and stirred for another 15 h. The mixture was cooled to room temperature, 75 kg of water was added, and the mixture was centrifuged, washed, and vacuum dried to obtain activated cellulose.

[0077] S3. Add steel fibers, graphene oxide, activated cellulose and water to the cementitious material and mix evenly to obtain a premix; mix the premix with activated glass fibers and spray.

[0078] The above-mentioned method for using ultra-high performance concrete in high-altitude and cold regions involves adding premixed materials to a mortar spraying machine for spraying; while activated glass fibers are mixed with the premixed materials and sprayed at the nozzle of the mortar spraying machine.

[0079] The operating parameters of the mortar spraying machine are as follows: conveying pressure is 3.2 MPa, and conveying flow rate is 2 m³ / s. 3 The spraying speed is 1 / min, the spraying distance is 1.3m, and the spraying thickness is controlled at 10mm per layer.

[0080] Comparative Example 1

[0081] A type of ultra-high performance concrete that can be sprayed in cold regions, the raw materials of which include premix and glass fiber, with the mass ratio of premix to glass fiber being 259.65:8.5.

[0082] The raw materials for the premix include: 75 kg of PO42.5 silicate cement, 15 kg of silica fume, 10 kg of fly ash, 72 kg of 16-26 mesh manufactured sand, 36 kg of 26-40 mesh quartz sand, 6 kg of 40-80 mesh fluorite ore waste sand, 6 kg of 40-80 mesh copper slag, 0.6 kg of polycarboxylate superplasticizer, 6 kg of alkali-free liquid quick-setting agent, 7 kg of microcrystalline cellulose, 1.5 kg of methyl methacrylate, 0.05 kg of cerium ammonium nitrate, 1.5 kg of ethylenediamine, 1.5 kg of methyl acrylate, 5 kg of steel fiber, 1.5 kg of graphene oxide, and 15 kg of water.

[0083] The preparation method of the above-mentioned ultra-high performance concrete that can be sprayed in high-altitude and cold regions includes the following steps:

[0084] S1. Add cement, silica fume, manufactured sand, quartz sand, fluorite mine waste sand, copper slag, water-reducing agent, and quick-setting agent to a mortar mixer and mix evenly to obtain a cementitious material.

[0085] S2. Microcrystalline cellulose was added to 30 kg of methanol and stirred evenly. Methyl methacrylate was added under nitrogen protection and stirred evenly. Cerium ammonium nitrate was added and stirred at 40℃ for 90 min. Ethylenediamine was added and stirred at 55℃ for 10 h. Methyl acrylate was added and stirred for another 15 h. The mixture was cooled to room temperature, 75 kg of water was added, and the mixture was centrifuged, washed, and vacuum dried to obtain activated cellulose.

[0086] S3. Add steel fibers, graphene oxide, activated cellulose and water to the cementitious material and mix evenly to obtain a premix; mix the premix with glass fiber and spray.

[0087] Comparative Example 2

[0088] A type of ultra-high performance concrete that can be sprayed in cold regions, the raw materials of which include: premix and activated glass fiber, the mass ratio of premix to activated glass fiber is 259.65:8.5.

[0089] The raw materials for the premix include: 75 kg of PO42.5 silicate cement, 15 kg of silica fume, 10 kg of fly ash, 72 kg of 16-26 mesh manufactured sand, 36 kg of 26-40 mesh quartz sand, 6 kg of 40-80 mesh fluorite ore waste sand, 6 kg of 40-80 mesh copper slag, 0.6 kg of polycarboxylate superplasticizer, 6 kg of alkali-free liquid quick-setting agent, 7 kg of microcrystalline cellulose, 1.5 kg of methyl methacrylate, 0.05 kg of cerium ammonium nitrate, 1.5 kg of ethylenediamine, 1.5 kg of methyl acrylate, 5 kg of steel fiber, 1.5 kg of graphene oxide, and 15 kg of water.

[0090] The activated glass fiber was prepared by the following specific operation: 7 kg of glass fiber was added to 40 kg of 0.8 mol / L sodium hydroxide aqueous solution and ultrasonically treated for 10 min at an ultrasonic frequency of 8 kHz. After filtration, washing, and vacuum drying, 1.5 kg of aminopropyltriethoxysilane was added to 40 kg of 50% ethanol aqueous solution and stirred at 85℃ for 90 min. After filtration, washing, and vacuum drying, the glass fiber was prepared.

[0091] The preparation method of the above-mentioned ultra-high performance concrete that can be sprayed in high-altitude and cold regions includes the following steps:

[0092] S1. Add cement, silica fume, manufactured sand, quartz sand, fluorite mine waste sand, copper slag, water-reducing agent, and quick-setting agent to a mortar mixer and mix evenly to obtain a cementitious material.

[0093] S2. Mix microcrystalline cellulose, methyl methacrylate, cerium ammonium nitrate, ethylenediamine, and methyl acrylate evenly to obtain pretreated microcrystalline cellulose;

[0094] S3. Add steel fibers, graphene oxide, pretreated microcrystalline cellulose and water to the gelling material and mix evenly to obtain a premix; mix the premix with activated glass fibers and spray.

[0095] The fluidity of the mortars obtained in Example 5 and Comparative Examples 1-2 was determined using a cement mortar fluidity tester in accordance with GB / T 2419-2005 "Method for Determination of Flowability of Cement Mortar".

[0096] Referring to GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)", mortar samples with dimensions of 40mm×40mm×160mm were cast from the mortar obtained in Example 5 and Comparative Examples 1-2. These samples were then cured in a high-temperature steam curing chamber at 50℃ for 28 days. After curing, a flexural strength test was performed first, followed by a compressive strength test on the broken prism. The compression surfaces were the two sides of the specimen during molding, with an area of ​​40mm×40mm.

[0097] Flexural strength was tested on a SANS YAW-100 compression-flexure testing machine. The side of the specimen was placed on the fixture, and the loading rate of the testing machine was 50±10 N / s. Then, the side of the broken specimen end was placed on the fixture, and the loading rate was set to 2400±200 N / s, and uniform loading was applied until the specimen failed.

[0098] As shown in Figures 1 and 2, the concrete obtained in Example 5 had the highest fluidity and 28-day flexural strength, which were superior to those of Comparative Examples 1-2 (P < 0.05). Moreover, the concrete obtained in Example 5 had the best early strength performance, with a 1-day compressive strength that reached 94.84% of the 28-day compressive strength. At the same time, the compressive strength of the concrete obtained in Example 5 was always higher than that of Comparative Examples 1-2 (P < 0.05).

[0099] The applicant believes that this is because the present invention grafts dendritic macromolecules onto the surface of microcrystalline cellulose, making the product surface rich in amino groups. Combined with the activation of glass fibers, the product is added to the system in steps, which enables ultra-high performance concrete to have good workability, improve its early hydration reaction, and significantly increase its early strength compared to ordinary concrete.

[0100] The impermeability grades of the concrete obtained in Example 5 and Comparative Examples 1-2 after 28 days of curing were tested in accordance with GB 50164-2011 "Standard for Quality Control of Concrete". The impermeability grade of the concrete obtained in Example 5 reached P40, the impermeability grade of the concrete obtained in Comparative Example 1 was P27, and the impermeability grade of the concrete obtained in Comparative Example 2 was P19.

[0101] The applicant believes that this invention grafts dendritic macromolecules onto the surface of microcrystalline cellulose, resulting in a product surface rich in amino groups. Combined with the activation of glass fibers, the product is added to the system stepwise. In conjunction with the effect of graphene oxide, it exhibits excellent water resistance. Furthermore, the two-dimensional plane of graphene oxide has a large number of functionalizable binding sites, which, when combined with activated cellulose, increase the stability of the system. It can also form intermolecular hydrogen bonds with water molecules, inhibiting water molecule crystallization and effectively lowering the freezing point, making it particularly suitable for use in cold regions.

[0102] The mortars obtained in Example 5 and Comparative Examples 1-2 were used for vertical spraying on the wall according to the method used in Example 5. It was found that the mortar obtained in Example 5 had a uniform spray surface, while the spraying effect of Comparative Example 1 was not ideal, with occasional clogging and pulse "explosion" phenomena. Although Comparative Example 2 could be sprayed, the dispersion was uneven during spraying, and fiber clusters were visible to the naked eye on the sprayed surface.

[0103] The applicant believes that this invention uses activated cellulose to enhance the anti-sagging properties of the mortar, combined with activated glass fiber. The two are bonded together by hydrogen bonds, which binds the concrete cement with ultrafine composite powder, silica fume, fine sand and coarse sand, thereby improving the cohesiveness and filling properties of the slurry and solving the problem of uneven dispersion of the sprayed slurry.

[0104] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A type of ultra-high performance concrete that can be sprayed in high-altitude and cold regions, characterized in that, Its raw materials include: premix and activated glass fiber, with a mass ratio of premix to activated glass fiber of 220-300:6-12; the raw materials of the premix, by mass, include: 70-80 parts cement, 10-20 parts silica fume, 5-15 parts fly ash, 70-75 parts coarse sand, 33-39 parts fine sand, 10-15 parts ultrafine composite powder, 4-6 parts water-reducing agent, 4-8 parts quick-setting agent, 5-10 parts microcrystalline cellulose, 1-2 parts methyl methacrylate, 0.01-0.1 parts cerium ammonium nitrate, 1-2 parts ethylenediamine, 1-2 parts methyl acrylate, 3-7 parts steel fiber, 1-2 parts graphene oxide, and 13-17 parts water; and microcrystalline fiber is used. Activated cellulose was prepared from cellulose, methyl methacrylate, cerium ammonium nitrate, ethylenediamine, and methyl acrylate as follows: Microcrystalline cellulose was added to methanol and stirred until homogeneous. Methyl methacrylate was added under nitrogen protection and stirred until homogeneous. Cerium ammonium nitrate was added and stirred at 30-50℃ for 1-2 hours. Ethylenediamine was added and stirred at 50-60℃ for 5-15 hours. Methyl acrylate was added and stirring was continued for 10-20 hours. The mixture was cooled to room temperature, water was added, and the mixture was centrifuged, washed, and vacuum dried to obtain activated cellulose. The ultrafine composite powder was obtained from fluorite ore waste sand and / or copper slag. Activated glass fiber was obtained by treating glass fiber with alkali solution and then heating it together with siloxane in an ethanol aqueous solution.

2. The ultra-high performance concrete for high-altitude and cold regions according to claim 1, characterized in that, The cement is PO42.5 silicate cement.

3. The ultra-high performance concrete for high-altitude and cold regions according to claim 1, characterized in that, The coarse sand is 16-26 mesh manufactured sand, the fine sand is 26-40 mesh quartz sand, and the ultrafine composite powder is 40-80 mesh.

4. The ultra-high performance concrete for high-altitude and cold regions according to claim 1, characterized in that, Activated glass fibers are prepared by the following specific operation: glass fibers are added to an aqueous sodium hydroxide solution and ultrasonically treated for 5-15 minutes, filtered, washed, and vacuum dried. The solution is then added to an aqueous ethanol solution with aminopropyltriethoxysilane, stirred at 80-90℃ for 1-2 hours, filtered, washed, and vacuum dried.

5. The ultra-high performance concrete for high-altitude and cold regions according to claim 4, characterized in that, The mass ratio of glass fiber to aminopropyltriethoxysilane is 5-10:1-2.

6. The ultra-high performance concrete for high-altitude and cold regions according to claim 4, characterized in that, The concentration of sodium hydroxide aqueous solution is 0.5-1.2 mol / L, and the mass fraction of ethanol aqueous solution is 40-60%.

7. A method for using sprayable ultra-high performance concrete in high-altitude and cold regions as described in any one of claims 1-6, characterized in that, The premixed material is added to the mortar spraying machine for spraying, while the activated glass fiber is mixed with the premixed material and sprayed at the nozzle of the mortar spraying machine.

8. The method for using sprayable ultra-high performance concrete in high-altitude and cold regions according to claim 7, characterized in that, The operating parameters of the mortar spraying machine are as follows: conveying pressure is 2.5-4.2MPa, and conveying flow rate is 1-3m³ / h. 3 The spraying speed is 1-1.6m, and the spraying thickness is controlled at 5-15mm per layer.

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