A durable high-strength concrete and its preparation method

Abstract

The present invention discloses a durable high-strength concrete and a preparation method thereof, relating to the technical field of concrete. The concrete is made of the following components by weight: 60-80 parts of cement, 60-75 parts of manufactured sand, 35-60 parts of crushed stone, 15-30 parts of silica fume, 10-15 parts of fly ash, 10-20 parts of slag powder, 15-25 parts of modified aramid fiber, 3-8 parts of water reducer, 2-6 parts of defoamer, and 10-20 parts of water. The concrete of the present invention forms a highly dense and uniform microstructure inside, significantly improving the anti-seepage, anti-corrosion and freeze-thaw resistance capabilities, and can long-term resist physical erosion and chemical deterioration under harsh environments. The unique enhanced network design effectively inhibits crack propagation, endowing the material with excellent impact toughness and fatigue durability, and greatly extending the service life of the structure.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and particularly relates to a durable high-strength concrete and a preparation method thereof. Background Art

[0002] As the most widely used structural material in contemporary engineering construction, the performance of concrete is directly related to the safety and service life of infrastructure. Traditional concrete is a composite material prepared by mixing cement, sand, stone, water and various admixtures in a certain proportion, and forms a solid overall structure through the hydration reaction of cement. With the rapid development of large-scale projects such as super high-rise buildings, cross-sea bridges, and water conservancy projects, higher requirements are put forward for the strength and durability of concrete. High-strength concrete is widely used in engineering due to its excellent load-bearing capacity, but traditional high-strength concrete often has problems of insufficient durability, especially in marine, cold and corrosive environments, it is extremely easy to appear early deterioration phenomena.

[0003] Among the basic components of concrete, cement, as the main binder, has a decisive influence on the performance of concrete in terms of its variety, quality and dosage; sand and gravel aggregates provide the skeleton structure of concrete, and their gradation, purity and mechanical properties directly affect the workability and strength of concrete; water is the necessary medium for cement hydration, and water quality and water-cement ratio have an important influence on the durability of concrete; admixtures such as water reducers, antifreeze agents, air-entraining agents, etc. improve the performance of concrete by changing the physical and chemical properties of the cement paste. In recent years, the application of active admixtures such as silica fume, fly ash and slag powder has been increasingly widespread, and these materials significantly improve the microstructure and long-term performance of concrete through pozzolanic reaction, filling effect and early activation.

[0004] The concrete performance evaluation system mainly includes three aspects: mechanical properties, durable properties and workability. Mechanical properties include compressive strength, tensile strength, flexural strength and elastic modulus, etc.; durable properties cover impermeability, freeze-thaw resistance, carbonation resistance, chloride ion permeability resistance and sulfate erosion resistance, etc.; workability mainly examines the fluidity, cohesiveness, water retention and bleeding of concrete. In actual engineering, these performances often restrict each other and it is difficult to reach the optimal state at the same time.

[0005] At present, the conventional measures to improve the durability of concrete mainly include: reducing the water-cement ratio, adding active admixtures and admixtures, optimizing the particle gradation, etc. Although these methods can improve the performance of concrete to a certain extent, it is still difficult to meet the dual requirements of high strength and high durability at the same time. Especially in terms of crack resistance, with the increase of strength, the brittleness of concrete increases, the impact resistance and fatigue resistance decrease significantly, and it is easy to generate and expand microcracks, resulting in the deterioration of the long-term performance of the structure and the shortening of the service life. In a high-alkalinity environment, problems such as alkali-aggregate reaction and alkali-silica reaction of concrete are becoming increasingly prominent, seriously restricting the long-term service performance of concrete.

[0006] Adding fiber reinforcement is an effective way to improve the toughness of concrete. However, conventional fibers such as steel fibers and polypropylene fibers are prone to uneven dispersion, weak interfacial bonding, and poor durability in concrete. Moreover, the hydrophilicity and alkali stability of the fiber surface are insufficient, resulting in rapid performance degradation in a high-alkali cement environment. Aramid fibers, due to their high strength, high modulus, and excellent chemical corrosion resistance, can theoretically be used as ideal concrete reinforcement materials.

[0007] CN116589241A discloses an aramid fiber-reinforced high-performance concrete, which comprises raw materials in the following weight parts ratio: 30-50 parts of cement, 60-70 parts of a mixed base material, 0.9-1.3 parts of a water reducer, 5-7 parts of aramid fibers, 1-2 parts of fly ash, 0.5-0.8 parts of a binder, and 10-20 parts of a cementitious material. The mixed base material consists of sand, gravel, and water.

[0008] However, the inertness and hydrophobicity of the aramid fiber surface lead to poor interfacial bonding with the cement matrix, restricting the exertion of its reinforcement effect. In addition, the composite reinforcement systems in the existing technologies are often complex in process and high in cost, making it difficult to be popularized and applied in engineering practice.

[0009] Therefore, the research and development of new concrete materials with both high strength and high durability, especially the development of fiber reinforcement systems with excellent dispersibility, interfacial bonding property, and alkali resistance, are of great significance for extending the service life of infrastructure, reducing maintenance costs, and improving engineering safety. Summary of the Invention

[0010] In order to solve the deficiencies existing in the prior art, the purpose of the present invention is to provide a durable high-strength concrete and its preparation method. A highly dense and uniform microstructure is formed inside the concrete, significantly improving the anti-seepage, anti-corrosion, and freeze-thaw resistance capabilities, and enabling long-term resistance to physical erosion and chemical deterioration under harsh environments. The unique reinforcement network design effectively inhibits crack propagation, endowing the material with excellent impact toughness and fatigue durability, and greatly extending the service life of the structure.

[0011] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0012] A durable high-strength concrete is made from the following components in parts by weight: 60-80 parts of cement, 60-75 parts of manufactured sand, 35-60 parts of gravel, 15-30 parts of silica fume, 10-15 parts of fly ash, 10-20 parts of slag powder, 15-25 parts of modified aramid fibers, 3-8 parts of a water reducer, 2-6 parts of an antifoaming agent, and 10-20 parts of water.

[0013] Preferably, the manufactured sand has a particle size of 2-3.5 mm.

[0014] Preferably, the gravel particle size is 8-12 mm.

[0015] Preferably, the mass percentage of silicon dioxide in the silica fume is not less than 96%, the average particle size is 0.05-0.2 μm, and the specific surface area is not less than 17000 m 2 / kg.

[0016] Preferably, the fly ash is Class I fly ash.

[0017] Preferably, the mineral powder is S95 grade slag powder.

[0018] Preferably, the water reducing agent is a polycarboxylate water reducing agent.

[0019] Preferably, the preparation method of the modified aramid fiber comprises the following steps:

[0020] (1) Place the aramid fiber in an argon / oxygen mixed gas, perform plasma treatment, then immerse it in an ethanol aqueous solution, add KH560, oscillate in a water bath, filter, wash with alcohol, and dry the product to obtain pretreated fibers;

[0021] Plasma activation and KH560 grafting: In the mixed gas of argon and oxygen, high-energy particles generated by the plasma bombard the surface of the aramid fiber, breaking the C-H bonds in the molecular chain and generating free radicals. These free radicals react with oxygen to form hydroxyl groups, significantly increasing the hydroxyl density on the fiber surface. Subsequently, the methoxy groups of the KH560 silane coupling agent are hydrolyzed into silanols in the ethanol-water system, combine with the hydroxyl groups on the fiber surface through hydrogen bonds, and dehydrate and condense under heating conditions to form stable Si-O-C covalent bonds. This process grafts epoxy groups on the fiber surface, providing active sites for subsequent reactions.

[0022] Preferably, in step (1), the diameter of the aramid fiber is 7-10 μm and the length is 12-15 mm.

[0023] Preferably, in step (1), the volume ratio of argon to oxygen in the argon / oxygen mixed gas is 4:1, and the plasma treatment is carried out at 80-100 W and room temperature for 10-30 min.

[0024] Preferably, in step (1), the dosage ratio of aramid fiber, ethanol aqueous solution, and KH560 is 10 g:100-150 mL:2-6 g; the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 8-9:1-2.

[0025] Preferably, in step (1), the water bath oscillation condition is to oscillate and react at 65-80 °C for 3-6 h.

[0026] (2) Immerse the pretreated fiber in DMF, add gallic acid and DMAP, stir and react in an oil bath, control the pH of the system, filter, neutralize, wash and dry the product to obtain the intermediate fiber;

[0027] Epoxy ring-opening esterification of gallic acid: In a DMF solvent, DMAP catalyzes the ring-opening of the epoxy group to generate an oxygen anion intermediate. The carboxylic acid group of gallic acid is partially deprotonated under weakly alkaline conditions and selectively attacks the carbon atom after ring-opening as a nucleophile to form a β-hydroxy ester bond. Due to steric hindrance effects and differences in the electronic environment, the phenolic hydroxyl group in the gallic acid molecule does not participate in the reaction in this step.

[0028] Preferably, in step (2), the dosage ratio of the pretreated fiber, DMF, gallic acid, and DMAP is 10 g: 100 - 120 mL: 0.5 - 1.5 g: 6 - 18 mg.

[0029] Preferably, in step (2), triethylamine is added to control the pH of the reaction system to 8 - 9; the stirring reaction conditions are stirring and reacting at 50 - 65 °C and 800 - 1000 r / min for 7 - 10 h.

[0030] (3) Immerse the intermediate fiber in DMF, add 1,3-propane sultone and potassium carbonate, reflux and react under a nitrogen atmosphere, filter, wash and dry the product to obtain the modified aramid fiber.

[0031] Ring-opening grafting of sultone: The β-hydroxy group on the surface of the intermediate fiber is deprotonated under alkaline catalysis to form a strongly nucleophilic oxygen anion, which attacks the carbonyl carbon of the sultone to initiate a ring-opening reaction. After ring-opening, the generated sulfonic acid group is stabilized by intramolecular proton transfer, and the newly generated hydroxyl group continues to initiate chain growth to form a polymer side chain containing sulfonic acid groups. It should be noted that due to the large steric hindrance and weak acidity of the phenolic hydroxyl group in the gallic acid molecule, it is difficult to be effectively deprotonated under alkaline conditions, so it does not participate in the ring-opening reaction of the sultone.

[0032] Preferably, in step (3), the dosage ratio of the intermediate fiber, DMF, 1,3-propane sultone, and potassium carbonate is 10 g: 100 - 150 mL: 1.2 - 3.0 g: 8 - 16 mg.

[0033] Preferably, in step (3), the reflux reaction conditions are refluxing and reacting at 75 - 90 °C for 12 - 16 h.

[0034] The present invention also claims a preparation method of the durable high-strength concrete as described above, including the following steps: Mix cement, manufactured sand, crushed stone, silica fume, fly ash, mineral powder, and modified aramid fiber, stir evenly to obtain a dry mix, and then mix water, water reducer, and defoamer with the dry mix, and stir evenly to obtain the durable high-strength concrete.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The present invention provides a durable high-strength concrete. The composite cementitious system of cement, silica fume, fly ash, and slag forms a dense microstructure. The micro-filling effect of silica fume significantly reduces the porosity. The spherical particles of fly ash improve the fluidity of the paste and reduce the cement dosage, thereby reducing the accumulation of hydration heat and temperature stress. The optimized gradation of manufactured sand and gravel strengthens the aggregate skeleton support. With the synergistic regulation of water-reducing agent and defoaming agent, high fluidity and low bubble defects are achieved at a low water-binder ratio. The three-dimensional dispersion network of modified aramid fibers effectively inhibits early plastic shrinkage cracks, reduces water migration by blocking capillary channels, and reduces pore connectivity, thereby improving the impermeability. The physical support of the fibers can also reduce aggregate settlement and surface bleeding, inhibit volume shrinkage during the plastic stage, and ensure the continuity of the overall concrete structure.

[0037] 2. The present invention provides a modified aramid fiber. First, the grafting of silane coupling agent significantly improves the chemical bonding force between the fiber and the cement matrix, reduces fiber agglomeration at the same time, and improves its dispersion uniformity in concrete. Second, the benzene ring structure introduced by the grafting of gallic acid enhances the rigidity and chemical corrosion resistance of the fiber through the conjugation effect. Its hydroxyl functional groups further form hydrogen bonds and coordination bonds with cement hydration products (such as Ca²⁺, silicate network), strengthening the interfacial anchoring effect. Subsequently, the sulfonic acid groups grafted on the surface cooperate with the water-reducing agent through electrostatic repulsion to optimize the dispersion of cement particles, significantly improving the fluidity and density of the paste. The three-dimensional network structure formed by the fibers in the concrete matrix effectively inhibits the initiation and propagation of microcracks through the dual mechanisms of mechanical interlocking and chemical bonding, and reduces the water migration rate by blocking capillary channels, thereby greatly improving the impermeability. In addition, the strong interfacial bonding between the fiber and the matrix can disperse the shrinkage stress and the temperature stress generated by freeze-thaw cycles, limit the development of cracks and delay the surface spalling, ultimately endowing the concrete with excellent freeze-thaw resistance and long-term structural integrity. Detailed implementation manners

[0038] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in conjunction with embodiments. Of course, the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased through market channels or synthesized from raw materials purchased through market channels.

[0040] The aramid fiber is purchased from Guangdong Teweilong New Material Application Co., Ltd., with a diameter of 7 - 10 μm and a length of 12 - 15 mm;

[0041] The polycarboxylate water reducer was purchased from Guangdong Ruian Technology Industry Co., Ltd., with the model LS-JS;

[0042] The defoamer is a polyether defoamer, with the model MY-9100;

[0043] Silica fume was purchased from Borun New Materials Technology Co., Ltd.;

[0044] The mineral powder is S95 grade slag powder, purchased from Shijiazhuang Mayue Building Materials Co., Ltd.

[0045] A preparation method of a durable high-strength concrete includes the following steps:

[0046] (1) Place the aramid fiber in an argon / oxygen mixed gas (the volume ratio of argon to oxygen is 4:1), perform plasma treatment at 80 - 100 W and room temperature for 10 - 30 min, then immerse 10 g of the plasma-treated aramid fiber in 100 - 150 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 8 - 9:1 - 2), add 2 - 6 g of KH560, perform a water bath oscillation reaction at 65 - 80 °C for 3 - 6 h, filter, wash with alcohol, and dry the product to obtain pretreated fiber;

[0047] (2) Immerse 10 g of the pretreated fiber in 100 - 120 mL of DMF, add 0.5 - 1.5 g of gallic acid and 6 - 18 mg of DMAP, stir and react in an oil bath at 50 - 65 °C and 800 - 1000 r / min for 7 - 10 h, add triethylamine to control the pH of the reaction system to 8 - 9, filter, neutralize, wash, and dry the product to obtain intermediate fiber;

[0048] (3) Immerse 10 g of the intermediate fiber in 100 - 150 mL of DMF, add 1.2 - 3.0 g of 1,3-propane sultone and 8 - 16 mg of potassium carbonate, reflux and react in a nitrogen atmosphere at 75 - 90 °C for 12 - 16 h, filter, wash, and dry the product to obtain modified aramid fiber;

[0049] (4) Mix 60 - 80 parts of cement, 60 - 75 parts of machine-made sand, 35 - 60 parts of gravel, 15 - 30 parts of silica fume, 10 - 15 parts of fly ash, 10 - 20 parts of mineral powder, and 15 - 25 parts of modified aramid fiber, stir evenly to obtain a dry mixture, then mix 3 - 8 parts of water reducer, 2 - 6 parts of defoamer, and 10 - 20 parts of water with the dry mixture, and stir evenly to obtain the durable high-strength concrete.

[0050] The following is a further description of the present invention through specific examples.

[0051] Example 1

[0052] A preparation method of a durable high-strength concrete includes the following steps:

[0053] (1) Place the aramid fiber in an argon / oxygen mixed gas (the volume ratio of argon to oxygen is 4:1), and perform plasma treatment at 100 W and room temperature for 15 min. Then immerse 10 g of the plasma-treated aramid fiber in 150 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 6 g of KH560, and react with shaking in a water bath at 80 °C for 3 h. Filter, wash with alcohol, and dry the product to obtain the pretreated fiber;

[0054] (2) Immerse 10 g of the pretreated fiber in 120 mL of DMF, add 1.5 g of gallic acid and 18 mg of DMAP, and stir and react in an oil bath at 65 °C and 1000 r / min for 7 h. Add triethylamine to control the pH of the reaction system to 8.5. Filter, neutralize, wash, and dry the product to obtain the intermediate fiber;

[0055] (3) Immerse 10 g of the intermediate fiber in 120 mL of DMF, add 3.0 g of 1,3-propane sultone and 16 mg of potassium carbonate, and reflux and react in a nitrogen atmosphere at 90 °C for 12 h. Filter, wash, and dry the product to obtain the modified aramid fiber;

[0056] (4) Mix 800 g of cement, 750 g of manufactured sand, 600 g of crushed stone, 300 g of silica fume, 150 g of fly ash, 200 g of mineral powder, and 250 g of the modified aramid fiber, stir evenly to obtain the dry mix. Then mix 80 g of water reducing agent, 60 g of defoamer, and 200 g of water with the dry mix, and stir evenly to obtain the durable high-strength concrete.

[0057] Example 2

[0058] A preparation method of a durable high-strength concrete, comprising the following steps:

[0059] (1) Place the aramid fiber in an argon / oxygen mixed gas (the volume ratio of argon to oxygen is 4:1), and perform plasma treatment at 100 W and room temperature for 15 min. Then immerse 10 g of the plasma-treated aramid fiber in 150 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 5 g of KH560, and react with shaking in a water bath at 75 °C for 4 h. Filter, wash with alcohol, and dry the product to obtain the pretreated fiber;

[0060] (2) Immerse 10 g of the pretreated fiber in 120 mL of DMF, add 1.2 g of gallic acid and 14 mg of DMAP, and stir and react in an oil bath at 60 °C and 1000 r / min for 8 h. Add triethylamine to control the pH of the reaction system to 8.5. Filter, neutralize, wash, and dry the product to obtain the intermediate fiber;

[0061] (3) Immerse 10 g of intermediate fibers into 120 mL of DMF, add 2.4 g of 1,3 - propanesultone and 14 mg of potassium carbonate, and reflux for 13 h at 85 °C under a nitrogen atmosphere. Filter, wash, and dry the product to obtain modified aramid fibers;

[0062] (4) Mix 750 g of cement, 700 g of manufactured sand, 500 g of crushed stone, 250 g of silica fume, 140 g of fly ash, 180 g of slag powder, and 210 g of modified aramid fibers, stir evenly to obtain a dry - mix material. Then mix 60 g of water - reducing agent, 50 g of defoamer, and 180 g of water with the dry - mix material, and stir evenly to obtain the durable high - strength concrete.

[0063] Example 3

[0064] A preparation method of a durable high - strength concrete, comprising the following steps:

[0065] (1) Place aramid fibers in an argon / oxygen mixed gas (the volume ratio of argon to oxygen is 4:1), perform plasma treatment at 100 W and room temperature for 15 min. Then immerse 10 g of the plasma - treated aramid fibers into 150 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 4 g of KH560, and react by shaking in a water bath at 70 °C for 5 h. Filter, wash with alcohol, and dry the product to obtain pretreated fibers;

[0066] (2) Immerse 10 g of pretreated fibers into 120 mL of DMF, add 0.8 g of gallic acid and 10 mg of DMAP, stir and react at 55 °C in an oil bath at 1000 r / min for 9 h, add triethylamine to control the pH of the reaction system to 8.5. Filter, neutralize, wash, and dry the product to obtain intermediate fibers;

[0067] (3) Immerse 10 g of intermediate fibers into 120 mL of DMF, add 1.8 g of 1,3 - propanesultone and 12 mg of potassium carbonate, reflux for 13 h at 80 °C under a nitrogen atmosphere. Filter, wash, and dry the product to obtain modified aramid fibers;

[0068] (4) Mix 680 g of cement, 650 g of manufactured sand, 400 g of crushed stone, 200 g of silica fume, 120 g of fly ash, 140 g of slag powder, and 180 g of modified aramid fibers, stir evenly to obtain a dry - mix material. Then mix 50 g of water - reducing agent, 30 g of defoamer, and 130 g of water with the dry - mix material, and stir evenly to obtain the durable high - strength concrete.

[0069] Example 4

[0070] A preparation method of a durable high - strength concrete, comprising the following steps:

[0071] (1) Place the aramid fiber in an argon / oxygen mixed gas (the volume ratio of argon to oxygen is 4:1), and perform plasma treatment at 100 W and room temperature for 15 min. Then immerse 10 g of the plasma-treated aramid fiber in 150 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 2 g of KH560, and carry out a water bath oscillation reaction at 65 °C for 6 h. Filter, wash with alcohol, and dry the product to obtain the pretreated fiber;

[0072] (2) Immerse 10 g of the pretreated fiber in 120 mL of DMF, add 0.5 g of gallic acid and 6 mg of DMAP, and stir and react at 50 °C in an oil bath at 1000 r / min for 10 h. Add triethylamine to control the pH of the reaction system to 8.5. Filter, neutralize, wash, and dry the product to obtain the intermediate fiber;

[0073] (3) Immerse 10 g of the intermediate fiber in 120 mL of DMF, add 1.2 g of 1,3-propane sultone and 8 mg of potassium carbonate, and reflux and react at 75 °C in a nitrogen atmosphere for 16 h. Filter, wash, and dry the product to obtain the modified aramid fiber;

[0074] (4) Mix 600 g of cement, 600 g of manufactured sand, 350 g of crushed stone, 150 g of silica fume, 100 g of fly ash, 100 g of slag powder, and 150 g of modified aramid fiber, stir evenly to obtain a dry mix, and then mix 30 g of water reducing agent, 20 g of defoaming agent, and 100 g of water with the dry mix, stir evenly to obtain the durable high-strength concrete.

[0075] Comparative Example 1

[0076] A method for preparing concrete, comprising the following steps:

[0077] (1) Place the aramid fiber in an argon / oxygen mixed gas (the volume ratio of argon to oxygen is 4:1), and perform plasma treatment at 100 W and room temperature for 15 min. Then immerse 10 g of the plasma-treated aramid fiber in 150 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 6 g of KH560, and carry out a water bath oscillation reaction at 80 °C for 3 h. Filter, wash with alcohol, and dry the product to obtain the pretreated fiber;

[0078] (2) Immerse 10 g of the pretreated fiber in 120 mL of DMF, add 1.5 g of gallic acid and 18 mg of DMAP, and stir and react at 65 °C in an oil bath at 1000 r / min for 7 h. Add triethylamine to control the pH of the reaction system to 8.5. Filter, neutralize, wash, and dry the product to obtain the intermediate fiber;

[0079] (3) Mix 800 g of cement, 750 g of manufactured sand, 600 g of crushed stone, 300 g of silica fume, 150 g of fly ash, 200 g of slag powder, and 250 g of intermediate fiber, and stir evenly to obtain a dry mix. Then mix 80 g of water reducing agent, 60 g of defoamer, and 200 g of water with the dry mix, and stir evenly to obtain the concrete.

[0080] Comparative Example 2

[0081] A method for preparing concrete, comprising the following steps:

[0082] (1) Place aramid fiber in an argon / oxygen mixed gas (the volume ratio of argon to oxygen is 4:1), and perform plasma treatment at 100 W and room temperature for 15 min. Then immerse 10 g of the plasma-treated aramid fiber in 150 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 6 g of KH560, and perform a water bath oscillation reaction at 80 °C for 3 h. Filter, wash with alcohol, and dry the product to obtain pretreated fiber.

[0083] (2) Mix 800 g of cement, 750 g of manufactured sand, 600 g of crushed stone, 300 g of silica fume, 150 g of fly ash, 200 g of slag powder, and 250 g of pretreated fiber, and stir evenly to obtain a dry mix. Then mix 80 g of water reducing agent, 60 g of defoamer, and 200 g of water with the dry mix, and stir evenly to obtain the concrete.

[0084] Load and cast the concrete slurries prepared in Examples 1 to 4 and Comparative Examples 1 to 2. During the casting process, the concrete slurries are respectively subjected to a 10-min oscillation treatment with a cement oscillator in an automatic filling mold, then sent to a curing chamber for curing for 28 h, and then demolded and placed in normal temperature water for standard curing for 28 days to obtain concrete specimens. The humidity of the curing chamber is 90 - 95%, and the temperature is 24 - 25 °C.

[0085] Refer to GB / T 50081-2019 "Standard Test Methods for Physical and Mechanical Properties of Concrete" to test the compressive strength and flexural strength of concrete at 3 days and 28 days; refer to the step-by-step pressure application method in GB / T 50081-2019 "Standard Test Methods for Physical and Mechanical Properties of Concrete" to test the water penetration depth of standard specimens; refer to GB / T 50081-2019 "Standard Test Methods for Physical and Mechanical Properties of Concrete" to test the impermeability pressure of standard specimens; refer to GB / T 50081-2019 "Standard Test Methods for Physical and Mechanical Properties of Concrete" to make standard specimens, and calculate the number of cracks per unit area and the total cracking area per unit area after 24 hours of concrete pouring; refer to the "rapid freezing method" in GB / T 50082-2024 "Standard Test Methods for Long-Term and Durability Properties of Concrete", the freezing and thawing solution is saturated sodium chloride solution, and the freeze-thaw resistance performance is characterized by the number of cycles when the mass loss rate exceeds 5% and the relative elastic modulus drops to 60% of the initial value. The specific data are shown in Table 1.

[0086]

[0087] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A durable high-strength concrete, characterized in that: The invention is made of the following components by weight: 60-80 parts of cement, 60-75 parts of machine-made sand, 35-60 parts of crushed stone, 15-30 parts of silica fume, 10-15 parts of fly ash, 10-20 parts of mineral powder, 15-25 parts of modified aramid fiber, 3-8 parts of water reducing agent, 2-6 parts of defoaming agent and 10-20 parts of water. The modified aramid fiber is prepared by the following method steps: (1) Placing the aramid fiber in an argon / oxygen mixed gas for plasma treatment, then immersing it in an ethanol aqueous solution, adding KH560, shaking in a water bath, filtering the product, washing with alcohol, and drying it to obtain a pretreated fiber; (2) immersing the pretreated fiber in DMF, adding gallic acid and DMAP, stirring the reaction in an oil bath, controlling the pH of the system, filtering, neutralizing, washing, and drying the product to obtain an intermediate fiber; (3) The intermediate fiber is immersed in DMF, 1,3-propanesulfonate and potassium carbonate are added, and reflux reaction is carried out under a nitrogen atmosphere. The product is filtered, washed, and dried to obtain a modified aramid fiber.

2. The durable high-strength concrete according to claim 1, characterized in that: In step (1), the volume ratio of argon to oxygen in the argon / oxygen mixed gas is 4:1, the plasma treatment is 80-100W, and the treatment is carried out at room temperature for 10-30 minutes.

3. The durable high-strength concrete according to claim 1, characterized in that: In step (1), the usage ratio of aramid fiber, ethanol aqueous solution and KH560 is 10 g: 100-150 mL: 2-6 g; the volume ratio of ethanol and deionized water in the ethanol aqueous solution is 8-9: 1-2.

4. The durable high-strength concrete according to claim 1, characterized in that: In step (1), the water bath oscillation condition is oscillating reaction at 65-80° C. for 3-6 hours.

5. The durable high-strength concrete according to claim 1, characterized in that: In step (2), the usage ratio of pretreated fiber, DMF, gallic acid and DMAP is 10 g: 100-120 mL: 0.5-1.5 g: 6-18 mg.

6. The durable high-strength concrete according to claim 1, characterized in that: In step (2), triethylamine is added to control the pH of the reaction system to 8-9; the stirring reaction conditions are 50-65° C. and 800-1000 r / min for 7-10 hours.

7. The durable high-strength concrete according to claim 1, characterized in that: In step (3), the usage ratio of the intermediate fiber, DMF, 1,3-propanesulfonate, and potassium carbonate is 10 g: 100-150 mL: 1.2-3.0 g: 8-16 mg.

8. The durable high-strength concrete according to claim 1, characterized in that: In step (3), the reflux reaction conditions are reflux reaction at 75-90° C. for 12-16 hours.

9. A method for preparing durable high-strength concrete according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing cement, machine-made sand, crushed stone, silica fume, fly ash, mineral powder and modified aramid fiber, stirring evenly to obtain a dry mix, then mixing water, a water reducing agent and a defoaming agent with the dry mix, stirring evenly to obtain the durable high-strength concrete.

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