High-strength anti-crack concrete material and preparation method thereof

Abstract

The invention discloses a high-strength anti-crack concrete material and a preparation method thereof, and relates to the technical field of concrete. The prepared high-strength anti-crack concrete material is prepared from Portland cement, river sand, modified basalt fibers, modified polyacrylonitrile fibers, a defoaming agent, a water reducing agent and fly ash. The modified basalt fiber is obtained by reacting pretreated basalt fiber with 4-amino-2-tert-butylphenol and then reacting with 2-pyrazinyl ethanethiol, and the modified basalt fiber is obtained; the modified polyacrylonitrile fiber is obtained by reacting hydrolyzed polyacrylonitrile fiber with thiosemicarbazide, then reacting with 2, 4-difluorobromoacetophenone, then reacting with phosphorus oxychloride and N 'N-dimethylformamide, and then cross-linking with 5, 5'-diamino-2, 2 '-dipyridyl, and the modified polyacrylonitrile fiber is obtained by the following steps: reacting hydrolyzed polyacrylonitrile fiber with thiosemicarbazide, reacting with 2, 4-difluorobromoacetophenone, reacting with phosphorus oxychloride and N' N-dimethylformamide, and cross-linking with 5, 5 '-diamino-2, 2'-dipyridyl. The prepared high-strength anti-cracking concrete material has high strength, anti-aging performance and antibacterial performance.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, in particular to a high-strength crack-resistant concrete material and a preparation method thereof. Background Art

[0002] Concrete is made of cement, sand, stone, additives and other materials in a certain proportion. Compared with traditional concrete, high-strength crack-resistant concrete has better performance, so it is more and more widely used in construction projects, such as high-rise buildings, bridges, tunnels, underground projects, water conservancy and hydropower projects, etc. In these projects, the application of high-strength crack-resistant concrete can improve the safety and stability of the project, extend the service life of the project, and reduce the cost of repair and maintenance.

[0003] In order to improve the strength and crack resistance of concrete, it can be achieved by doping with a variety of materials. For example, fiber-reinforced materials are one of the most widely used concrete crack resistance materials. The addition of these fibers can effectively improve the tensile strength and crack resistance of concrete, while also enhancing the durability and impact resistance of concrete; high-strength crack-resistant concrete requires good anti-aging properties, mainly because during use, concrete will be affected by various natural and artificial factors, such as wind, sun, rain erosion, temperature changes, etc., all of which will cause the performance of concrete to gradually deteriorate. Therefore, in order to improve the durability of concrete, measures need to be taken to enhance its anti-aging properties; in some special environments, such as sewer systems, marine engineering, underground engineering and other humid environments, concrete structures are easily attached and colonized by microorganisms such as bacteria and fungi, affecting the working performance, mechanical properties and durability of concrete. Therefore, high-strength crack-resistant concrete used in these environments also needs to have good antibacterial properties. Summary of the invention

[0004] The purpose of the present invention is to provide a high-strength crack-resistant concrete material and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A method for preparing a high-strength crack-resistant concrete material comprises the following preparation steps: (1) Pretreated basalt fiber, N,N-dimethylformamide, and 4-amino-2-tert-butylphenol were mixed in a mass ratio of 1:(30-40):(0.1-0.2), heated to 40-50°C for reaction for 4 hours, and after the reaction, filtered and washed with pure water for 3-4 times, and dried under vacuum for 24 hours to obtain pre-modified basalt fiber; (2) Weigh 2-pyrazinylethanethiol and polyformaldehyde in a molar ratio of 1:2; mix the pre-modified basalt fiber, 2-pyrazinylethanethiol, N,N-dimethylformamide and piperidine in a mass ratio of 1:(0.2-0.3):(10-12):(1-2), add polyformaldehyde, heat to 80°C and stir for 10-12 minutes, heat to 110°C and reflux for 8 hours, filter after the reaction, wash with pure water for 5-6 times, and dry under vacuum for 24 hours to obtain modified basalt fiber; (3) Mix the hydrolyzed polyacrylonitrile fiber, thiosemicarbazide, and phosphorus oxychloride in a mass ratio of 1: (0.2-0.3): (10-12), heat to 75°C and react for 30-40 minutes, cool to room temperature, add pure water 20-30 times the mass of the hydrolyzed polyacrylonitrile fiber, heat to 100°C and reflux for 2-3 hours, after the reaction is completed, cool to 0°C, use saturated sodium hydroxide solution to adjust the pH to 8, filter and wash with pure water 5-6 times, and vacuum dry at 60°C for 24 hours to obtain pre-modified polyacrylonitrile fiber; mix the pre-modified polyacrylonitrile fiber, 2,4-difluorobromoacetophenone, anhydrous ethanol, and N,N-dimethylformamide in a mass ratio of 1: (0.3-0.4): (20-30): (1-2), heat Reflux at 78°C for 20h, after the reaction is completed, adjust the pH to 7-8 with a saturated sodium hydroxide solution, filter and wash with pure water for 5-6 times, and vacuum dry at 60°C for 24h to obtain fluorinated polyacrylonitrile fiber; mix phosphorus oxychloride and N,N-dimethylformamide at a mass ratio of 1:5 for 30min, add fluorinated polyacrylonitrile fiber with a mass of 7-8 times that of phosphorus oxychloride, stir at 0°C for 30min, heat to room temperature and continue stirring for 30min, then heat to 60°C and stir for 2h, after stirring, add an ice-water mixture with a mass of 10-12 times that of phosphorus oxychloride, adjust the pH to 7-8 with a saturated sodium hydroxide solution, filter and wash with pure water for 5-6 times, and vacuum dry at 60°C for 24h to obtain a modified polyacrylonitrile fiber precursor; (4) Mixing a modified polyacrylonitrile fiber precursor, N,N-dimethylformamide, and 5,5'-diamino-2,2'-bipyridine in a mass ratio of 1:(30-40):(0.3-0.4), heating to 40-50°C for reaction for 4 hours, filtering and washing with pure water for 3-4 times, and drying under vacuum for 24 hours to obtain modified polyacrylonitrile fiber; (5) Weigh the following raw materials: by mass: 100-200 parts of silicate cement, 80-120 parts of river sand, 15-25 parts of modified polyacrylonitrile fiber, 1-5 parts of defoamer, 1-10 parts of water reducer, 10-12 parts of modified basalt fiber, and 30-50 parts of fly ash; mix the above raw materials evenly, add 60-80 parts of water, put into a mixer and stir for 10-30 minutes to obtain a high-strength crack-resistant concrete material.

[0006] As an optimization, the preparation method of the pretreated basalt fiber in step (1) is as follows: basalt fiber and triethoxysilyl undecanedialdehyde solution are mixed in a mass ratio of 1:10, ultrasonically treated at room temperature for 7 hours, filtered and washed three times with ethanol after the ultrasonic treatment, and vacuum dried to obtain the pretreated basalt fiber; the silane coupling agent solution is obtained by mixing triethoxysilyl undecanedialdehyde and ethanol aqueous solution, the mass fraction of triethoxysilyl undecanedialdehyde in the silane coupling agent solution is 2.5%, and the ethanol aqueous solution is obtained by mixing ethanol and pure water in a mass ratio of 1:1.

[0007] As an optimization, the preparation method of the hydrolyzed polyacrylonitrile fiber in step (3) is: polyacrylonitrile fiber, sodium hydroxide and pure water are mixed in a mass ratio of 1:(10-12):100, stirred at 80°C for 30-40 minutes, taken out and washed with pure water for 5-6 times, and vacuum dried at 60°C for 12 hours to obtain hydrolyzed polyacrylonitrile fiber.

[0008] As an optimization, the silicate cement in step (5) is P.O42.5; the river sand particle size is 1-2 mm; the defoamer is polyether defoamer YS-001; the water reducer is polycarboxylic acid water reducer PC-1; and the fly ash is first-grade fly ash with a fineness of 11.7%.

[0009] As an optimization, the polyacrylonitrile fiber has a length of 12, a diameter of 18 μm, and a density of 1.5 g / cm 3 .

[0010] As an optimization, the basalt fiber has a length of 12 mm and a diameter of 18 μm.

[0011] The present invention also provides a high-strength crack-resistant concrete material prepared by the method for preparing the high-strength crack-resistant concrete material.

[0012] Compared with the prior art, the beneficial effects achieved by the present invention are: The high-strength crack-resistant concrete material prepared by the invention comprises silicate cement, river sand, modified basalt fiber, modified polyacrylonitrile fiber, defoamer, water reducer and fly ash; the modified basalt fiber is obtained by reacting pretreated basalt fiber with 4-amino-2-tert-butylphenol and then with 2-pyrazinylethanethiol; the modified polyacrylonitrile fiber is obtained by reacting hydrolyzed polyacrylonitrile fiber with thiosemicarbazide and then with 2,4-difluorobromoacetophenone, then with phosphorus oxychloride and N'N-dimethylformamide, and then cross-linking with 5,5'-diamino-2,2'-bipyridine.

[0013] First, triethoxysilyl undecanal is used to pretreat basalt fiber, so that the basalt fiber has aldehyde groups. The aldehyde groups and 4-amino-2-tert-butylphenol are grafted onto the surface of the basalt fiber through the Schiff base reaction. The aldehyde groups and 2-pyrazinylethanethiol are then reacted to form a thioether structure. The thioether structure is a good auxiliary antioxidant, which can produce a synergistic effect with hindered phenol antioxidants. Hindered phenol antioxidants mainly capture free radicals. After the free radical capture reaction, hydroperoxides will be obtained. Hindered phenol antioxidants cannot decompose hydroperoxides, while the thioether structure can terminate the oxidation process of the material by decomposing hydroperoxides. The reaction with 2-pyrazinylethanethiol can also graft pyridine functional groups onto the basalt fiber. Secondly, the polyacrylonitrile fiber is hydrolyzed with sodium hydroxide to make the fiber surface have carboxyl functional groups. Then, the carboxyl groups on the fiber surface undergo acylation reaction using hydrolyzed polyacrylonitrile fiber and thiosemicarbazide as raw materials and phosphorus oxychloride as solvent, and then undergo cyclization reaction with thiosemicarbazide to generate a thiadiazole structure; then, it reacts with 2,4-difluorobromoacetophenone to generate an imidazothiadiazole functional group with antibacterial properties, and at the same time, a fluorophenyl functional group with electron-withdrawing properties is introduced to further improve the antibacterial properties, thereby giving the material good antibacterial properties; then, phosphorus oxychloride and N'N-dimethylformamide are used to generate chloroimide salts, and the chloroimide salts introduce aldehyde groups on the imidazothiadiazole heterocycle through a formylation reaction, and the aldehyde group 5,5'-diamino-2,2'-bipyridine undergoes a Schiff base reaction to cross-link inside the polyacrylonitrile fiber, which can compensate for the loss of mechanical properties of polyacrylonitrile due to alkaline hydrolysis, and at the same time, a bipyridine structure is introduced into the polyacrylonitrile.

[0014] Finally, silicate cement, river sand, modified polyacrylonitrile fiber, defoamer, water reducer, modified basalt fiber and fly ash are mixed to obtain high-strength crack-resistant concrete material; the chopped basalt fiber is a rigid fiber and can well improve the strength of cement-based materials; the pyridine structure on the basalt fiber, the imidazothiadiazole structure and the pyridine structure on the modified polyacrylonitrile fiber have good complexing ability for metal ions such as calcium and aluminum in cement, which can further increase the density of the cross-linked network, thereby improving the mechanical properties of the material. DETAILED DESCRIPTION

[0015] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] In the following examples and comparative examples, the silicate cement is P.O42.5; the river sand particle size is 1-2 mm; the defoamer is polyether defoamer YS-001; the water reducer is polycarboxylate water reducer PC-1; the fly ash is first-class fly ash with a fineness of 11.7%; the polyacrylonitrile fiber is 12 in length, 18 μm in diameter, and 1.5 g / cm in density. 3 ; The basalt fiber has a length of 12 mm and a diameter of 18 μm. Example

[0017] A method for preparing a high-strength crack-resistant concrete material, the method for preparing the high-strength crack-resistant concrete material comprising the following preparation steps: (1) Basalt fiber and triethoxysilyl undecanedialdehyde solution were mixed in a mass ratio of 1:10, and ultrasonically treated at room temperature for 7 hours. After the ultrasonic treatment, the mixture was filtered and washed three times with ethanol, and then dried under vacuum to obtain pretreated basalt fiber; the silane coupling agent solution was obtained by mixing triethoxysilyl undecanedialdehyde and ethanol aqueous solution, the mass fraction of triethoxysilyl undecanedialdehyde in the silane coupling agent solution was 2.5%, and the ethanol aqueous solution was obtained by mixing ethanol and pure water in a mass ratio of 1:1; the pretreated basalt fiber, N,N-dimethylformamide, and 4-amino-2-tert-butylphenol were mixed in a mass ratio of 1:30:0.1, heated to 50°C for reaction for 4 hours, filtered after the reaction, washed four times with pure water, and then dried under vacuum for 24 hours to obtain pre-modified basalt fiber; (2) Weigh 2-pyrazinylethanethiol and polyformaldehyde in a molar ratio of 1:2; mix the pre-modified basalt fiber, 2-pyrazinylethanethiol, N,N-dimethylformamide and piperidine in a mass ratio of 1:0.2:10:1, add polyformaldehyde, heat to 80°C and stir for 12 minutes, heat to 110°C and reflux for 8 hours, filter after the reaction, wash with pure water 6 times, and dry under vacuum for 24 hours to obtain modified basalt fiber; (3) Mix polyacrylonitrile fiber, sodium hydroxide and pure water in a mass ratio of 1:10:100, stir at 80°C for 40 minutes, take out and wash with pure water for 6 times, and vacuum dry at 60°C for 12 hours to obtain hydrolyzed polyacrylonitrile fiber; mix hydrolyzed polyacrylonitrile fiber, thiosemicarbazide and phosphorus oxychloride in a mass ratio of 1:0.2:10, heat to 75°C and react for 40 minutes, cool to room temperature, add pure water 20 times the mass of the hydrolyzed polyacrylonitrile fiber, heat to 100°C and reflux for 3 hours, after the reaction is completed, cool to 0°C, adjust the pH to 8 with saturated sodium hydroxide solution, filter and wash with pure water for 5 times, and vacuum dry at 60°C for 24 hours to obtain pre-modified polyacrylonitrile fiber; mix pre-modified polyacrylonitrile fiber, 2,4-difluorobromoacetophenone, anhydrous ethanol, N , N-dimethylformamide in a mass ratio of 1:0.3:20:1, heated to 78°C and refluxed for 20 hours. After the reaction, a saturated sodium hydroxide solution was used to adjust the pH to 7, filtered and washed with pure water for 6 times, and vacuum dried at 60°C for 24 hours to obtain fluorinated polyacrylonitrile fiber; phosphorus oxychloride and N,N-dimethylformamide were mixed in a mass ratio of 1:5 for 30 minutes, and 7 times the mass of phosphorus oxychloride was added to the fluorinated polyacrylonitrile fiber. After stirring at 0°C for 30 minutes, the mixture was heated to room temperature and continued to stir for 30 minutes, and then heated to 60°C and stirred for 2 hours. After the stirring was completed, an ice-water mixture with a mass of 10 times the mass of phosphorus oxychloride was added, a saturated sodium hydroxide solution was used to adjust the pH to 8, filtered and washed with pure water for 6 times, and vacuum dried at 60°C for 24 hours to obtain a modified polyacrylonitrile fiber precursor; (4) Mixing a modified polyacrylonitrile fiber precursor, N,N-dimethylformamide, and 5,5'-diamino-2,2'-bipyridine in a mass ratio of 1:30:0.3, heating to 50°C for reaction for 4 hours, filtering and washing with pure water for 4 times after the reaction, and drying under vacuum for 24 hours to obtain modified polyacrylonitrile fiber; (5) Weigh the following raw materials: by mass: 100 parts of silicate cement, 80 parts of river sand, 15 parts of modified polyacrylonitrile fiber, 1 part of defoamer, 1 part of water reducer, 10 parts of modified basalt fiber, and 30 parts of fly ash; mix the above raw materials evenly, add 60 parts of water, put into a mixer and stir for 30 minutes to obtain a high-strength crack-resistant concrete material. Example

[0018] A method for preparing a high-strength crack-resistant concrete material, the method for preparing the high-strength crack-resistant concrete material comprising the following preparation steps: (1) Basalt fiber and triethoxysilyl undecanedialdehyde solution were mixed in a mass ratio of 1:10, and ultrasonically treated at room temperature for 7 hours. After the ultrasonic treatment, the mixture was filtered and washed three times with ethanol, and then dried under vacuum to obtain pretreated basalt fiber; the silane coupling agent solution was obtained by mixing triethoxysilyl undecanedialdehyde and ethanol aqueous solution, the mass fraction of triethoxysilyl undecanedialdehyde in the silane coupling agent solution was 2.5%, and the ethanol aqueous solution was obtained by mixing ethanol and pure water in a mass ratio of 1:1; the pretreated basalt fiber, N,N-dimethylformamide, and 4-amino-2-tert-butylphenol were mixed in a mass ratio of 1:35:0.15, heated to 45°C for reaction for 4 hours, filtered after the reaction, washed four times with pure water, and then dried under vacuum for 24 hours to obtain pre-modified basalt fiber; (2) Weigh 2-pyrazinylethanethiol and polyformaldehyde in a molar ratio of 1:2; mix the pre-modified basalt fiber, 2-pyrazinylethanethiol, N,N-dimethylformamide and piperidine in a mass ratio of 1:0.25:11:1.5, add polyformaldehyde, heat to 80°C and stir for 11 minutes, heat to 110°C and reflux for 8 hours, filter after the reaction, wash with pure water 5 times, and dry under vacuum for 24 hours to obtain modified basalt fiber; (3) Mix polyacrylonitrile fiber, sodium hydroxide and pure water in a mass ratio of 1:11:100, stir at 80°C for 35 minutes, take out and wash with pure water for 6 times, and vacuum dry at 60°C for 12 hours to obtain hydrolyzed polyacrylonitrile fiber; mix hydrolyzed polyacrylonitrile fiber, thiosemicarbazide and phosphorus oxychloride in a mass ratio of 1:0.25:11, heat to 75°C and react for 35 minutes, cool to room temperature, add pure water 25 times the mass of the hydrolyzed polyacrylonitrile fiber, heat to 100°C and reflux for 2.5 hours, after the reaction is completed, cool to 0°C, adjust the pH to 8 with saturated sodium hydroxide solution, filter and wash with pure water for 5 times, and vacuum dry at 60°C for 24 hours to obtain pre-modified polyacrylonitrile fiber; mix pre-modified polyacrylonitrile fiber, 2,4-difluorobromoacetophenone, anhydrous ethanol, N,N- Dimethylformamide was mixed in a mass ratio of 1:0.35:25:1.5, heated to 78°C and refluxed for 20 hours. After the reaction was completed, a saturated sodium hydroxide solution was used to adjust the pH to 7.5, filtered and washed with pure water for 5 times, and vacuum dried at 60°C for 24 hours to obtain fluorinated polyacrylonitrile fiber; phosphorus oxychloride and N,N-dimethylformamide were mixed in a mass ratio of 1:5 for 30 minutes, 7.5 times the mass of phosphorus oxychloride was added to the fluorinated polyacrylonitrile fiber, stirred at 0°C for 30 minutes, heated to room temperature and continued to stir for 30 minutes, then heated to 60°C and stirred for 2 hours. After the stirring was completed, an ice-water mixture with 11 times the mass of phosphorus oxychloride was added, a saturated sodium hydroxide solution was used to adjust the pH to 7.5, filtered and washed with pure water for 5 times, and vacuum dried at 60°C for 24 hours to obtain a modified polyacrylonitrile fiber precursor; (4) Mixing a modified polyacrylonitrile fiber precursor, N,N-dimethylformamide, and 5,5'-diamino-2,2'-bipyridine in a mass ratio of 1:35:0.35, heating to 45°C for reaction for 4 hours, filtering and washing with pure water for 3 times after the reaction, and drying under vacuum for 24 hours to obtain modified polyacrylonitrile fiber; (5) Weigh the following raw materials: by mass: 150 parts of silicate cement, 100 parts of river sand, 20 parts of modified polyacrylonitrile fiber, 3 parts of defoaming agent, 6 parts of water reducer, 11 parts of modified basalt fiber, and 40 parts of fly ash; mix the above raw materials evenly, add 70 parts of water, put into a mixer and stir for 20 minutes to obtain a high-strength crack-resistant concrete material. Example

[0019] A method for preparing a high-strength crack-resistant concrete material, the method for preparing the high-strength crack-resistant concrete material comprising the following preparation steps: (1) Basalt fiber and triethoxysilyl undecanedialdehyde solution were mixed in a mass ratio of 1:10, and ultrasonically treated at room temperature for 7 hours. After the ultrasonic treatment, the mixture was filtered and washed three times with ethanol, and then dried under vacuum to obtain pretreated basalt fiber; the silane coupling agent solution was obtained by mixing triethoxysilyl undecanedialdehyde and ethanol aqueous solution, the mass fraction of triethoxysilyl undecanedialdehyde in the silane coupling agent solution was 2.5%, and the ethanol aqueous solution was obtained by mixing ethanol and pure water in a mass ratio of 1:1; the pretreated basalt fiber, N,N-dimethylformamide, and 4-amino-2-tert-butylphenol were mixed in a mass ratio of 1:40:0.2, heated to 40°C for reaction for 4 hours, filtered after the reaction, washed three times with pure water, and then dried under vacuum for 24 hours to obtain pre-modified basalt fiber; (2) Weigh 2-pyrazinylethanethiol and polyformaldehyde in a molar ratio of 1:2; mix the pre-modified basalt fiber, 2-pyrazinylethanethiol, N,N-dimethylformamide and piperidine in a mass ratio of 1:0.3:12:2, add polyformaldehyde, heat to 80°C and stir for 12 minutes, heat to 110°C and reflux for 8 hours, filter after the reaction, wash with pure water 6 times, and dry under vacuum for 24 hours to obtain modified basalt fiber; (3) Mix polyacrylonitrile fiber, sodium hydroxide and pure water in a mass ratio of 1:12:100, stir at 80°C for 30 minutes, take out and wash with pure water for 5 times, and vacuum dry at 60°C for 12 hours to obtain hydrolyzed polyacrylonitrile fiber; mix hydrolyzed polyacrylonitrile fiber, thiosemicarbazide and phosphorus oxychloride in a mass ratio of 1:0.3:12, heat to 75°C and react for 30 minutes, cool to room temperature, add pure water 30 times the mass of the hydrolyzed polyacrylonitrile fiber, heat to 100°C and reflux for 2 hours, after the reaction is completed, cool to 0°C, adjust the pH to 8 with saturated sodium hydroxide solution, filter and wash with pure water for 5 times, and vacuum dry at 60°C for 24 hours to obtain pre-modified polyacrylonitrile fiber; mix pre-modified polyacrylonitrile fiber, 2,4-difluorobromoacetophenone, anhydrous ethanol, N , N-dimethylformamide in a mass ratio of 1:0.4:30:2, heated to 78°C and refluxed for 20 hours. After the reaction, a saturated sodium hydroxide solution was used to adjust the pH to 7, filtered and washed with pure water for 5 times, and vacuum dried at 60°C for 24 hours to obtain fluorinated polyacrylonitrile fiber; phosphorus oxychloride and N,N-dimethylformamide were mixed in a mass ratio of 1:5 for 30 minutes, and 8 times the mass of phosphorus oxychloride was added to the fluorinated polyacrylonitrile fiber. After stirring at 0°C for 30 minutes, the mixture was heated to room temperature and continued to stir for 30 minutes, and then heated to 60°C and stirred for 2 hours. After the stirring was completed, an ice-water mixture with a mass of 12 times the mass of phosphorus oxychloride was added, a saturated sodium hydroxide solution was used to adjust the pH to 7, filtered and washed with pure water for 5 times, and vacuum dried at 60°C for 24 hours to obtain a modified polyacrylonitrile fiber precursor; (4) Mixing a modified polyacrylonitrile fiber precursor, N,N-dimethylformamide, and 5,5'-diamino-2,2'-bipyridine in a mass ratio of 1:40:0.4, heating to 40°C for reaction for 4 hours, filtering after the reaction, washing with pure water for 3 times, and drying under vacuum for 24 hours to obtain modified polyacrylonitrile fiber; (5) Weigh the following raw materials: 200 parts by mass of silicate cement, 120 parts by mass of river sand, 25 parts by mass of modified polyacrylonitrile fiber, 5 parts by mass of defoamer, 10 parts by mass of water reducer, 12 parts by mass of modified basalt fiber, and 50 parts by mass of fly ash; mix the above raw materials evenly, add 80 parts by mass of water, put into a mixer and stir for 10 minutes to obtain a high-strength crack-resistant concrete material.

[0020] Comparative Example 1: The preparation method of the high-strength and crack-resistant concrete material of Comparative Example 1 differs from that of Example 2 in that step (5) is modified as follows: weigh the following raw materials: 150 parts by mass of silicate cement, 100 parts by mass of river sand, 20 parts by mass of modified polyacrylonitrile fiber, 3 parts by mass of defoamer, 6 parts by mass of water reducer, 11 parts by mass of basalt fiber, and 40 parts by mass of fly ash; mix the above raw materials evenly, add 70 parts by mass of water, and mix the mixture in a mixer for 20 minutes to obtain a high-strength and crack-resistant concrete material.

[0021] Comparative Example 2: The preparation method of the high-strength and crack-resistant concrete material of Comparative Example 2 differs from that of Example 2 in step (5). Step (5) is modified as follows: weigh the following raw materials: 150 parts by mass of silicate cement, 100 parts by mass of river sand, 20 parts by mass of polyacrylonitrile fiber, 3 parts by mass of defoamer, 6 parts by mass of water reducer, 11 parts by mass of modified basalt fiber, and 40 parts by mass of fly ash; mix the above raw materials evenly, add 70 parts by mass of water, put into a mixer and stir for 20 minutes to obtain a high-strength and crack-resistant concrete material.

[0022] Comparative Example 3: The preparation method of the high-strength and crack-resistant concrete material of Comparative Example 3 differs from that of Example 2 in that steps (2) and (4) are not included, and step (5) is modified as follows: weigh the following raw materials: 150 parts by mass of silicate cement, 100 parts by mass of river sand, 20 parts by mass of modified polyacrylonitrile fiber precursor, 3 parts by mass of defoamer, 6 parts by mass of water reducer, 11 parts by mass of pre-modified basalt fiber, and 40 parts by mass of fly ash; mix the above raw materials evenly, add 70 parts by mass of water, put into a mixer and stir for 20 minutes to obtain a high-strength and crack-resistant concrete material.

[0023] The concrete materials obtained in the above embodiments and comparative examples were cured and then tested. The curing conditions were a curing temperature of 20° C., a humidity of 98%, and a curing time of 28 days.

[0024] Test Example 1: Mechanical properties test: Test method: The concrete materials obtained in all comparative examples and examples were prepared into specimens of 100 mm×100 mm×100 mm; and the compressive strength was tested according to the standard GB / T50081-2002. The results are shown in Table 1.

[0025] Test of anti-aging performance: The concrete materials obtained in all comparative examples and embodiments were prepared into 100mm×100mm×100mm specimens; the test blocks were placed in an ultraviolet aging box for strong ultraviolet radiation according to the standard GB / T50081-2002, wherein the conditions of strong ultraviolet radiation are: light intensity of 1160W / m, temperature of 80°C, and light exposure time of 300h. After the light exposure, the compressive strength was tested according to the test method of mechanical properties, and the compressive strength retention rate was calculated. The results are shown in Table 1.

[0026] Table 1

[0027] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, it can be found that the high-strength crack-resistant concrete material prepared by the present invention has good mechanical properties and anti-aging properties.

[0028] By comparison, the compressive strength of Examples 1 to 3 is greater than that of Comparative Examples 1 to 3, and the compressive strength retention rate of Examples 1 to 3 is greater than that of Comparative Examples 1 and 3; it indicates that the basalt fiber is pretreated with triethoxysilyl undecaldehyde, so that the basalt fiber has an aldehyde group, and the aldehyde group and 4-amino-2-tert-butylphenol are grafted on the surface of the basalt fiber through the Schiff base reaction with a hindered phenol structure having an antioxidant function, and then react with 2-pyrazinylethanethiol to form a thioether structure, which is a good auxiliary antioxidant, and can produce a synergistic effect with hindered phenol antioxidants. Hindered phenol antioxidants mainly capture free radicals, and hydroperoxides will be obtained after the free radical capture reaction. Hindered phenol antioxidants cannot decompose hydroperoxides, while the thioether structure can terminate the oxidation process of the material by decomposing hydroperoxides; and 2-pyrazinylethanethiol The reaction of ethyl mercaptan can also graft pyridine functional groups on basalt fiber; after hydrolyzing polyacrylonitrile fiber with sodium hydroxide, the fiber surface has carboxyl functional groups, and then the hydrolyzed polyacrylonitrile fiber and thiosemicarbazide are used as raw materials, and phosphorus oxychloride is used as solvent. The carboxyl groups on the fiber surface undergo acylation reaction, and then undergo cyclization reaction with thiosemicarbazide to generate a thiadiazole structure; and then react with 2,4-difluorobromoacetophenone to generate imidazothiadiazole functional groups; phosphorus oxychloride and N'N-dimethylformamide are then used to generate chloroimide salts, and the chloroimide salts introduce aldehyde groups on the imidazothiadiazole heterocycle through formylation reaction, and the aldehyde group 5,5'-diamino-2,2'-bipyridine undergoes Schiff base reaction to cross-link inside the polyacrylonitrile fiber, which can compensate for the loss of mechanical properties of polyacrylonitrile due to alkaline hydrolysis, and at the same time introduce bipyridine structure into polyacrylonitrile.

[0029] High-strength crack-resistant concrete material is obtained by mixing silicate cement, river sand, modified polyacrylonitrile fiber, defoamer, water reducer, modified basalt fiber and fly ash; the pyridine structure on the basalt fiber, the imidazothiadiazole structure on the modified polyacrylonitrile fiber and the pyridine structure have good complexing ability for metal ions such as calcium and aluminum in cement, which can further increase the density of the cross-linked network, thereby improving the mechanical properties of the material.

[0030] Test Example 2: Antibacterial performance test: Test method: The concrete materials prepared in the examples and comparative examples were crushed, and then filtered using a 0.08 nm standard sieve to obtain powder with a particle size less than 0.08 nm. 2 g of the powder was placed on a filter paper with a diameter of 1 cm, and the filter paper was placed in a solid culture medium smeared with bacterial liquid, and cultured at 37°C for 12 hours. The bacterial species was Staphylococcus aureus, and the size of the inhibition zone was determined using the Oxford cup method. The results are shown in Table 2.

[0031] Table 2

[0032] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 2, it can be found that the high-strength crack-resistant concrete material prepared by the present invention has good antibacterial properties.

[0033] By comparison, the antibacterial rates of Examples 1 to 3 are greater than that of Comparative Example 2, indicating that after the polyacrylonitrile fiber is hydrolyzed with sodium hydroxide, the fiber surface is provided with carboxyl functional groups, and then the carboxyl groups on the fiber surface undergo acylation reaction using the hydrolyzed polyacrylonitrile fiber and thiosemicarbazide as raw materials and phosphorus oxychloride as solvent, and then undergo cyclization reaction with thiosemicarbazide to generate a thiadiazole structure; and then react with 2,4-difluorobromoacetophenone to generate an imidazothiadiazole functional group with antibacterial properties, and at the same time, the introduction of a fluorophenyl functional group with electron-withdrawing properties can further improve the antibacterial properties, thereby giving the material good antibacterial properties.

[0034] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing a high-strength crack-resistant concrete material, characterized in that: The method comprises the following preparation steps: (1) Pretreated basalt fiber, N,N-dimethylformamide, and 4-amino-2-tert-butylphenol were mixed in a mass ratio of 1:(30-40):(0.1-0.2), heated to 40-50°C for reaction for 4 hours, and after the reaction, filtered and washed with pure water for 3-4 times, and dried under vacuum for 24 hours to obtain pre-modified basalt fiber; (2) Weigh 2-pyrazinylethanethiol and polyformaldehyde in a molar ratio of 1:2; mix the pre-modified basalt fiber, 2-pyrazinylethanethiol, N,N-dimethylformamide and piperidine in a mass ratio of 1:(0.2-0.3):(10-12):(1-2), add polyformaldehyde, heat to 80°C and stir for 10-12 minutes, heat to 110°C and reflux for 8 hours, filter after the reaction, wash with pure water for 5-6 times, and dry under vacuum for 24 hours to obtain modified basalt fiber; (3) Mix the hydrolyzed polyacrylonitrile fiber, thiosemicarbazide, and phosphorus oxychloride in a mass ratio of 1: (0.2-0.3): (10-12), heat to 75°C and react for 30-40 minutes, cool to room temperature, add pure water 20-30 times the mass of the hydrolyzed polyacrylonitrile fiber, heat to 100°C and reflux for 2-3 hours, after the reaction is completed, cool to 0°C, use saturated sodium hydroxide solution to adjust the pH to 8, filter and wash with pure water 5-6 times, and vacuum dry at 60°C for 24 hours to obtain pre-modified polyacrylonitrile fiber; mix the pre-modified polyacrylonitrile fiber, 2,4-difluorobromoacetophenone, anhydrous ethanol, and N,N-dimethylformamide in a mass ratio of 1: (0.3-0.4): (20-30): (1-2), heat Reflux at 78°C for 20h, after the reaction is completed, adjust the pH to 7-8 with a saturated sodium hydroxide solution, filter and wash with pure water for 5-6 times, and vacuum dry at 60°C for 24h to obtain fluorinated polyacrylonitrile fiber; mix phosphorus oxychloride and N,N-dimethylformamide at a mass ratio of 1:5 for 30min, add fluorinated polyacrylonitrile fiber with a mass of 7-8 times that of phosphorus oxychloride, stir at 0°C for 30min, heat to room temperature and continue stirring for 30min, then heat to 60°C and stir for 2h, after stirring, add an ice-water mixture with a mass of 10-12 times that of phosphorus oxychloride, adjust the pH to 7-8 with a saturated sodium hydroxide solution, filter and wash with pure water for 5-6 times, and vacuum dry at 60°C for 24h to obtain a modified polyacrylonitrile fiber precursor; (4) Mixing a modified polyacrylonitrile fiber precursor, N,N-dimethylformamide, and 5,5'-diamino-2,2'-bipyridine in a mass ratio of 1:(30-40):(0.3-0.4), heating to 40-50°C for reaction for 4 hours, filtering and washing with pure water for 3-4 times, and drying under vacuum for 24 hours to obtain modified polyacrylonitrile fiber; (5) Weigh the following raw materials: by mass: 100-200 parts of silicate cement, 80-120 parts of river sand, 15-25 parts of modified polyacrylonitrile fiber, 1-5 parts of defoamer, 1-10 parts of water reducer, 10-12 parts of modified basalt fiber, and 30-50 parts of fly ash; mix the above raw materials evenly, add 60-80 parts of water, put into a mixer and stir for 10-30 minutes to obtain a high-strength crack-resistant concrete material.

2. The method for preparing a high-strength crack-resistant concrete material according to claim 1, characterized in that: The preparation method of the pretreated basalt fiber in step (1) is as follows: basalt fiber and triethoxysilyl undecanedialdehyde solution are mixed in a mass ratio of 1:10, ultrasonically treated at room temperature for 7 hours, filtered and washed three times with ethanol after the ultrasonic treatment, and vacuum dried to obtain the pretreated basalt fiber; the silane coupling agent solution is obtained by mixing triethoxysilyl undecanedialdehyde and ethanol aqueous solution, the mass fraction of triethoxysilyl undecanedialdehyde in the silane coupling agent solution is 2.5%, and the ethanol aqueous solution is obtained by mixing ethanol and pure water in a mass ratio of 1:

1.

3. The method for preparing a high-strength crack-resistant concrete material according to claim 1, characterized in that: The preparation method of the hydrolyzed polyacrylonitrile fiber in step (3) is as follows: polyacrylonitrile fiber, sodium hydroxide and pure water are mixed in a mass ratio of 1:(10-12):100, stirred at 80°C for 30-40 minutes, taken out and washed with pure water for 5-6 times, and vacuum dried at 60°C for 12 hours to obtain the hydrolyzed polyacrylonitrile fiber.

4. The method for preparing a high-strength crack-resistant concrete material according to claim 1, characterized in that: In step (5), the silicate cement is P.O42.5; the river sand particle size is 1-2 mm; the defoamer is polyether defoamer YS-001; the water reducer is polycarboxylic acid water reducer PC-1; and the fly ash is first-grade fly ash with a fineness of 11.7%.

5. The method for preparing a high-strength crack-resistant concrete material according to claim 3, characterized in that: The polyacrylonitrile fiber has a length of 12, a diameter of 18 μm, and a density of 1.5 g / cm 3 .

6. The method for preparing a high-strength crack-resistant concrete material according to claim 2, characterized in that: The basalt fiber has a length of 12 mm and a diameter of 18 μm.

7. A high-strength crack-resistant concrete material prepared according to the method for preparing a high-strength crack-resistant concrete material according to any one of claims 1 to 6.

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