CF120 ultrahigh-strength concrete and preparation method thereof

Abstract

The invention discloses CF120 ultrahigh-strength concrete and a preparation method thereof. The concrete comprises the following raw materials in parts by weight: 500-600 parts of cement; 750 to 860 parts of sand; 1200 to 1350 parts of broken stone; 90 to 100 parts of fly ash; 75 to 83 parts of straw ash; 37 to 50 parts of silica fume; 145 to 160 parts of water; 15 to 20 parts of a water reducing agent; 15 to 20 parts of an exciting agent; 3-5 parts of a defoaming agent; 12-16 parts of a shrinkage reducing agent; 23 to 28 parts of CaCO3 crystal whisker; 20 to 30 parts of polyvinyl formal acetal; 20 to 30 parts of titanium dioxide loaded fiber; the titanium dioxide loaded fibers are prepared by modifying fibers with titanium dioxide; the fibers comprise at least one of steel fibers or polypropylene fibers. The CF120 ultrahigh-strength concrete provided by the invention has relatively high compressive strength and breaking strength, and the situation that the concrete generates cracks is also reduced.

Description

Technical Field

[0001] The present application relates to the technical field of building materials, and in particular to a CF120 ultra-high strength concrete and a preparation method thereof. Background Art

[0002] In the field of structural design, it is crucial to select the right grade of concrete to ensure the safety, economy and functionality of the structure. Concrete components under different stress conditions, such as columns under axial pressure, beams under bending moments or novel structures under complex stresses, require concrete of different strength levels to meet their compression, bending and splitting requirements, while also ensuring sufficient bond strength between concrete and steel bars to achieve the synergy of the two. The strength index of concrete must be carefully selected. Too high or too low will lead to the inability to fully exert the material properties or unreasonable component size. The former may cause material waste and insufficient structural rigidity, and the latter may cause the components to be too large to affect the use space, and even reduce the safety of the structure under extreme conditions such as earthquakes.

[0003] With the development of construction technology, the brittleness and crack resistance of traditional concrete have become increasingly prominent, especially in situations where high-strength concrete (such as C120) is required, such as the bottom load-bearing structure of high-rise buildings. Although these concretes have high strength, their brittle characteristics are more significant, reducing the seismic performance and safety of the structure. At the same time, the improvement of modern steel performance has also put forward higher requirements on the toughness, deformation capacity and bonding performance of concrete, and traditional concrete can no longer meet these requirements.

[0004] Although adding fibers, such as steel fibers and coconut shell fibers, to concrete can improve its compressive strength to a certain extent, the bonding strength between the fibers and the concrete matrix is ​​limited, and excessive addition may reduce the overall performance of concrete, leading to cracking problems during long-term use. In addition, heat accumulation during concrete pouring and curing, especially in large volumes of concrete, will produce temperature stress, aggravate the cracking tendency of concrete, and affect its durability and structural integrity. As the construction industry continues to increase its requirements for material performance, the limitations of traditional concrete in terms of strength, durability and economy are becoming increasingly apparent, which has prompted the industry to urgently develop new concrete materials to meet the high standards of modern construction for materials, that is, concrete with ultra-high strength and excellent durability to meet increasingly complex construction challenges. Summary of the invention

[0005] In order to solve at least one of the above technical problems and develop a concrete with high crack resistance, flexural strength and compressive strength, the present application provides a CF120 ultra-high strength concrete and a preparation method thereof.

[0006] In a first aspect, the present application provides a CF120 ultra-high strength concrete, wherein the concrete comprises the following raw materials by weight: 500-600 parts of cement; Sand 750-860 parts; 1200-1350 parts of crushed stone; Fly ash 90-100 parts; Straw ash 75-83 parts; Silica fume 37-50 parts; 145-160 parts of water; 15-20 parts of water reducing agent; 15-20 parts of stimulant; 3-5 parts of defoaming agent; 12-16 parts of shrinkage reducing agent; 23-28 parts of CaCO3 whiskers; 20-30 parts of polyvinyl formal; 20-30 parts of titanium dioxide loaded fiber; The titanium dioxide loaded fiber is prepared by modifying the fiber with titanium dioxide; the fiber comprises at least one of steel fiber and polypropylene fiber.

[0007] By adopting the above technical scheme, this application is to meet the higher strength and durability requirements of modern buildings for concrete, especially for the cracking problems of traditional concrete in crack resistance, compressive strength and cracking caused by temperature stress during maintenance. This technology proposes a super high strength concrete called CF120 and its preparation method. By carefully selecting and blending various raw materials, including cement, sand, crushed stone, fly ash, straw ash, silica ash, water, water reducer, activator, defoamer, shrinkage reducer, CaCO3 whisker, polyvinyl alcohol acetal and titanium dioxide loaded fiber, this technology aims to prepare a concrete material that has both extremely high compressive strength and can effectively inhibit crack formation. Cement and crushed stone constitute the basic skeleton of concrete, giving it the main compressive strength. Sand, as fine aggregate, works together with cement paste to enhance the density and overall stability of concrete. Fly ash and straw ash, as mineral admixtures, not only improve the later strength of concrete, but also improve its workability and durability. The addition of silica fume further optimizes the microstructure of concrete and enhances its crack resistance.

[0008] The reasonable ratio of water and water reducing agent ensures the fluidity and water retention of concrete mixture, while reducing the hydration heat, which is crucial to controlling temperature difference and cracking. The activator promotes the early hydration process of cement and accelerates the strength growth rate. The use of defoamer and shrinkage reducer helps to reduce the pores and shrinkage cracks inside the concrete, further improving the density and crack resistance of the concrete. The addition of CaCO3 whiskers increases the micro-rigidity of concrete, which helps to improve the compressive strength and thermal stability.

[0009] However, the core innovation of this technical solution lies in the compound use of polyvinyl alcohol acetaldehyde and titanium dioxide loaded fiber. As a modified polymer, polyvinyl alcohol acetaldehyde can not only significantly improve the bonding performance of concrete, but also form a mesh structure during the hardening process, effectively inhibit the expansion of microcracks, and improve the freeze-thaw cycle resistance of concrete. Titanium dioxide loaded fiber, by loading titanium dioxide onto steel fiber or polypropylene fiber, not only enhances the interfacial bonding strength of the fiber, but also forms a multi-dimensional reinforcement network inside the concrete, which can effectively absorb and disperse stress, significantly improving the crack resistance and toughness of concrete. In summary, CF120 ultra-high strength concrete achieves a significant improvement in concrete crack resistance, compressive strength and temperature stress control by finely regulating the synergistic effects of various components, especially the compound use of polyvinyl alcohol acetaldehyde and titanium dioxide loaded fiber, effectively solving the cracking problem of traditional concrete under high strength and complex stress states, and providing high-performance and high-durability material solutions for the modern construction industry.

[0010] Optionally, the fiber is prepared by compounding steel fiber and polypropylene fiber in a weight ratio of 1:1.

[0011] By adopting the above technical solution, steel fiber and polypropylene fiber are compounded in a weight ratio of 1:1. This carefully designed fiber combination makes full use of the complementary advantages of the two fibers to achieve the best reinforcement effect. Steel fiber can provide additional support when concrete is stressed, effectively delaying and controlling the formation and development of cracks, thereby significantly improving the crack resistance and impact resistance of concrete. Polypropylene fiber can form a uniformly distributed micro-reinforcement network inside the concrete, effectively reducing the plastic shrinkage cracks of concrete, while improving its resistance to freeze-thaw cycles. Compounding these two fibers in a ratio of 1:1 can achieve a perfect balance between mechanical properties and working performance. The combination of the rigidity of steel fiber and the flexibility of polypropylene fiber can not only significantly improve the crack resistance, impact resistance and fatigue resistance of concrete, but also improve the microstructure of concrete, enhance its overall uniformity and density, and thus improve its durability and service life.

[0012] Optionally, the titanium dioxide-loaded fiber is replaced by KH-791 modified titanium dioxide-loaded fiber.

[0013] By adopting the above technical solutions, KH-791 can effectively enhance the interfacial bonding strength between the fiber and the concrete matrix through its unique chemical structure, thereby improving the dispersion and compatibility of the fiber in the concrete. The bond between the modified fiber and the concrete matrix is ​​stronger, effectively absorbing and dispersing stress, significantly improving the crack resistance and toughness of the concrete, and maintaining good structural integrity even in complex stress environments. The photocatalytic activity of titanium dioxide is retained, further enhancing the self-cleaning ability of the concrete, while having a long-lasting antibacterial function, which is conducive to maintaining the sanitary environment of the building and reducing maintenance costs. The uniform dispersion of KH-791 modified fibers helps to form a more dense and uniform concrete microstructure, improves the density of the material, and thus enhances its impermeability and freeze-thaw resistance.

[0014] Optionally, the KH-791 modified titanium dioxide loaded fiber is replaced by graphene-coated KH-791 modified titanium dioxide loaded fiber.

[0015] By adopting the above technical solution and using graphene-coated KH-791 modified titanium dioxide-loaded fibers, CF120 ultra-high-strength concrete not only performs well in compressive strength and crack resistance, but also has higher durability and versatility, providing the modern construction industry with a high-performance, high-durability and multifunctional building material solution, reflecting the cutting-edge progress of building materials technology.

[0016] Optionally, the weight ratio of the polyvinyl formal and the titanium dioxide loaded fiber is (0.8-1):1.

[0017] By adopting the above technical solution, polyvinyl alcohol acetaldehyde can form a stronger interface bond with KH-791 modified titanium dioxide loaded fiber, improve the bonding between fiber and concrete matrix, make the fiber more evenly distributed in concrete, form a continuous reinforcement network, and significantly improve the crack resistance and toughness of concrete. The water retention and shrinkage reduction properties of polyvinyl alcohol acetaldehyde, combined with the effective dispersion of temperature stress by modified fibers, reduce the risk of cracking of concrete during the maintenance process, especially in large-volume concrete construction, can effectively control cracks caused by internal and external temperature differences, and improve the overall quality of concrete. Through the precise ratio of polyvinyl alcohol acetaldehyde and KH-791 modified titanium dioxide loaded fiber, CF120 ultra-high strength concrete has reached a high level in terms of crack resistance, mechanical properties, durability, temperature stress control and construction performance, providing the modern construction industry with high-performance concrete materials with superior performance, convenient construction and environmental protection, and strongly promoting the innovation and development of construction technology.

[0018] Optionally, the weight ratio of the polyvinyl formal to the titanium dioxide loaded fiber is 1:1.

[0019] Optionally, the total weight of the polyvinyl formal and the titanium dioxide loaded fibers accounts for 1.5-1.8% of the total weight of the CF120 ultra-high strength concrete.

[0020] By adopting the above technical scheme, by controlling the total weight of polyvinyl alcohol acetal and KH-791 modified titanium dioxide loaded fiber to 1.5-1.8% of the total weight of CF120 ultra-high strength concrete, this application not only achieves a comprehensive upgrade of concrete in terms of crack resistance, compressive strength, durability, temperature stress control and construction performance, but also takes into account environmental protection and economic benefits, providing the modern construction industry with high-performance, high-durability and environmentally friendly building materials solutions, and promoting the continuous advancement of construction technology.

[0021] Optionally, the method for preparing the titanium dioxide-loaded fiber comprises the following steps: A1. The fiber is immersed in a Na2CO3 solution, washed, immersed in anhydrous ethanol and acetone respectively, and dried to obtain a pretreated fiber; A2, adding tetrabutyl titanate dropwise into anhydrous ethanol and stirring, adding deionized water, the volume ratio of tetrabutyl titanate, anhydrous ethanol and deionized water is (1.5-2.5):(23-28):(130-140), and impregnating the pretreated fiber in S1 for 20-30 minutes to obtain a fiber mixed solution; A3. Heat the fiber mixture in a reaction kettle at a constant temperature of 100-130° C. for 2-3 hours, then take it out and cool it to room temperature, wash it, and dry it to obtain the titanium dioxide loaded fiber.

[0022] By adopting the above technical scheme, the fiber is first impregnated in a sodium carbonate (Na2CO3) solution, which is intended to remove impurities on the fiber surface, improve the surface activity of the fiber, and enhance the effect of subsequent titanium dioxide loading. Subsequently, the fiber is washed several times to remove residual sodium carbonate, and then immersed in anhydrous ethanol and acetone respectively to further purify the fiber surface, and finally dried at a suitable temperature to obtain pretreated fibers, creating favorable conditions for subsequent loading of titanium dioxide. The pretreated fiber is immersed in a mixed solution containing tetrabutyl titanate (Ti(OC4H9)4), anhydrous ethanol and deionized water, wherein the volume ratio of tetrabutyl titanate, anhydrous ethanol and deionized water is precisely controlled at (1.5-2.5):(23-28):(130-140). This sol-gel reaction process can ensure that titanium dioxide is uniformly deposited on the fiber surface, forming a stable and uniform coating, improving the interfacial bonding between the fiber and the concrete matrix, and at the same time giving the concrete excellent photocatalytic activity and antibacterial properties. The fiber mixture is heated at high temperature in the reactor to fully cure the titanium dioxide coating. This process lasts for 2-3 hours at a temperature of 100-130°C. High temperature treatment not only promotes the crystallization of titanium dioxide, but also ensures the stability of the coating and the structural integrity of the fiber. Subsequently, after the fiber is cooled to room temperature, it is repeatedly washed to remove unreacted residues, and finally dried under appropriate conditions to obtain the finished titanium dioxide-loaded fiber. Through the above preparation method, the application effect of titanium dioxide-loaded fiber in CF120 ultra-high strength concrete is significant, which not only enhances the crack resistance, compressive strength and durability of concrete, but also improves the environmental adaptability and hygienic performance of concrete through its unique photocatalytic and antibacterial properties, providing a high-performance, environmentally friendly and multifunctional building material solution for the modern construction industry.

[0023] Optionally, the preparation method of the graphene-coated KH-791 modified titanium dioxide-loaded fiber comprises the following steps: B1, adding KH-791 modified titanium dioxide-loaded fiber to an acidic aqueous solution, mixing evenly, heating to 7585° C., heat preservation for 810 h, and cooling to room temperature to obtain a mixture; B2. Add sodium hydroxide to the mixture and adjust the pH value to 89, then add nano graphene oxide, mix well, heat to 6070°C, keep warm for 45 hours, then add polyethylene glycol, mix well, continue to keep warm for 1215 hours, cool to room temperature, centrifuge, and air-dry to obtain the graphene-coated KH-791 modified titanium dioxide loaded fiber.

[0024] By adopting the above technical solution, the application of graphene-coated KH-791 modified titanium dioxide loaded fiber in CF120 ultra-high strength concrete not only significantly improves the crack resistance, compressive strength, thermal stability and environmental adaptability of concrete, but also through its unique electrical conductivity, thermal conductivity and antibacterial properties, it provides a high-performance, multifunctional and environmentally friendly building material solution for the modern construction industry, demonstrating the cutting-edge progress and innovation potential in the field of building materials science and technology.

[0025] Optionally, the weight ratio of the KH-791 modified titanium dioxide loaded fiber, nano graphene oxide, acidic solution, and polyethylene glycol is (23):(12)::(6070):(8-10); Optionally, the acidic aqueous solution is a mixture of hydrochloric acid solution and sulfuric acid solution, the weight ratio of the hydrochloric acid solution to the sulfuric acid solution is 1:1, the mass concentration of the hydrochloric acid solution is 8.11%, and the mass solubility of the sulfuric acid solution is 22.25%.

[0026] In a second aspect, the present application provides a method for preparing CF120 ultra-high strength concrete, the preparation method comprising the following steps: S1, the water is divided into three equal parts, the first part of the water is mixed with the water reducing agent to obtain the first mixed solution, and the second part of the water is mixed with the shrinkage reducing agent and the defoaming agent to obtain the second mixed solution; S2, cement, sand, crushed stone, fly ash, straw ash, silica fume, the third portion of water, and CaCO3 whiskers are mixed in order and placed in a pan mixer, and stirred for 1 minute; titanium dioxide-loaded fibers and polyvinyl alcohol acetal are then added, and stirred for 2-4 minutes; the first portion of the mixed solution prepared in step S1 is then added, and stirred for 3-5 minutes to prepare a third portion of the mixed solution; S3, add the activator to the third mixed solution, stir evenly for 3-5 minutes, and obtain the fourth mixed solution; S4. Add the second mixed liquid to the fourth mixed liquid, stir for another 23 minutes until the mixture is uniform, discharge the mixture to obtain a concrete mixture, and shape and cure the concrete mixture to obtain the CF120 ultra-high strength concrete.

[0027] By adopting the above-mentioned technical scheme and the preparation method provided by the above-mentioned application, CF120 ultra-high-strength concrete achieves the unity of high performance and high durability. It not only far exceeds the conventional concrete standards in terms of compressive strength, but also has excellent crack resistance, impact resistance, freeze-thaw cycle resistance and environmental adaptability, providing a reliable, efficient and environmentally friendly building material solution for the modern construction industry, and demonstrating the integrated innovation of building materials science and engineering technology.

[0028] Optionally, the standard curing method is: pouring the concrete mixture into a cast iron mold to form and vibrate it, leaving it to stand for 12 days in a standard curing room with a temperature of 20±2°C and a relative humidity of ≥95%, removing the mold, and then curing it in the standard curing room to the required age.

[0029] In summary, the present invention includes at least one of the following beneficial technical effects: 1. This application is to meet the higher strength and durability requirements of modern buildings for concrete, especially for the cracking problems of traditional concrete in crack resistance, compressive strength and temperature stress during maintenance. This technology proposes a super high strength concrete called CF120 and its preparation method. Through careful selection and deployment of various raw materials, including cement, sand, crushed stone, fly ash, straw ash, silica fume, water, water reducer, activator, defoamer, shrinkage reducer, CaCO3 whisker, polyvinyl alcohol acetaldehyde and titanium dioxide loaded fiber, this technology aims to prepare a concrete material that has both extremely high compressive strength and can effectively inhibit crack formation. Cement and crushed stone constitute the basic skeleton of concrete, giving it the main compressive strength. Sand, as fine aggregate, works together with cement paste to enhance the density and overall stability of concrete. Fly ash and straw ash, as mineral admixtures, not only improve the later strength of concrete, but also improve its workability and durability. The addition of silica fume further optimizes the microstructure of concrete and enhances its crack resistance. The reasonable ratio of water and water reducing agent ensures the fluidity and water retention of concrete mixture, while reducing the hydration heat, which is crucial to controlling temperature difference and cracking. The activator promotes the early hydration process of cement and accelerates the strength growth rate. The use of defoamer and shrinkage reducer helps to reduce the pores and shrinkage cracks inside the concrete, further improving the density and crack resistance of the concrete. The addition of CaCO3 whiskers increases the micro-rigidity of concrete, which helps to improve the compressive strength and thermal stability.

[0030] However, the core innovation of this technical solution lies in the compounding of polyvinyl alcohol acetaldehyde and titanium dioxide loaded fibers. As a modified polymer, polyvinyl alcohol acetaldehyde can not only significantly improve the bonding properties of concrete, but also form a mesh structure during the hardening process, effectively inhibit the expansion of microcracks, and improve the freeze-thaw cycle resistance of concrete. Titanium dioxide loaded fibers, by loading titanium dioxide onto steel fibers or polypropylene fibers, not only enhance the interfacial bonding strength of the fibers, but also give concrete excellent photocatalytic activity and antibacterial properties. More importantly, these fibers form a multi-dimensional reinforcement network inside the concrete, which can effectively absorb and disperse stress, and significantly improve the crack resistance and toughness of concrete. In summary, CF120 ultra-high-strength concrete achieves a significant improvement in concrete crack resistance, compressive strength and temperature stress control by finely regulating the synergistic effects of various components, especially the compounding of polyvinyl alcohol acetaldehyde and titanium dioxide loaded fibers, effectively solving the cracking problem of traditional concrete under high strength and complex stress states, and providing high-performance and high-durability material solutions for the modern construction industry.

[0031] 2. KH-791 can effectively enhance the interfacial bonding strength between the fiber and the concrete matrix through its unique chemical structure, thereby improving the dispersion and compatibility of the fiber in the concrete. The bond between the modified fiber and the concrete matrix is ​​stronger, effectively absorbing and dispersing stress, significantly improving the crack resistance and toughness of the concrete, and maintaining good structural integrity even in complex stress environments. The photocatalytic activity of titanium dioxide is retained, further enhancing the self-cleaning ability of concrete, while having a long-lasting antibacterial function, which is conducive to maintaining the sanitary environment of the building and reducing maintenance costs. The uniform dispersion of KH-791 modified fibers helps to form a more dense and uniform concrete microstructure, improves the density of the material, and thus enhances its impermeability and freeze-thaw resistance.

[0032] 3. By controlling the total weight of polyvinyl alcohol acetal and KH-791 modified titanium dioxide loaded fiber to 1.5-1.8% of the total weight of CF120 ultra-high strength concrete, this application not only achieves a comprehensive upgrade of concrete in terms of crack resistance, compressive strength, durability, temperature stress control and construction performance, but also takes into account environmental protection and economic benefits, providing the modern construction industry with high-performance, high-durability and environmentally friendly building materials solutions, and promoting the continuous advancement of construction technology.

[0033] 4. Through the preparation method provided in the present application, CF120 ultra-high-strength concrete achieves the unity of high performance and high durability. It not only far exceeds the conventional concrete standards in terms of compressive strength, but also has excellent crack resistance, impact resistance, freeze-thaw cycle resistance and environmental adaptability, providing a reliable, efficient and environmentally friendly building material solution for the modern construction industry, demonstrating the integration and innovation of building materials science and engineering technology. DETAILED DESCRIPTION

[0034] The present application is further described in detail below with reference to the embodiments.

[0035] Cement: P·O52.5R grade ordinary Portland cement, Wuxi Jianghuai Building Materials Technology Co., Ltd.

[0036] Sand: Shenyang Rongxinda Engineering Materials Co., Ltd., thickness is 3-5mm.

[0037] Gravel: particle size range is 5mm15mm.

[0038] Fly ash: Lingshou County Wanzhu Mineral Products Co., Ltd., mesh size 200 mesh.

[0039] Straw ash: Guangxi Zhuangfang Liyuan Biotechnology Co., Ltd.

[0040] Silica fume: Shijiazhuang Baijiang Mineral Products Co., Ltd., porosity 0.0015%.

[0041] Water reducer: high efficiency polycarboxylic acid water reducer, Jinan Yucai Chemical Co., Ltd.

[0042] Defoaming agent: polyacrylate defoaming agent, Xiangyang Fuding Environmental Protection Technology Co., Ltd., product model FD-1050.

[0043] Shrinkage reducing agent: SU-SRA type shrinkage reducing agent, Shanghai Dewenuo New Material Technology Co., Ltd.

[0044] CaCO3 whiskers: Shijiazhuang Shuoheng New Material Technology Co., Ltd., active ingredient content 99.9%.

[0045] Polyvinyl alcohol acetaldehyde: CAS No. 252364-22-0, content is 99%.

[0046] Titanium dioxide: Zhengzhou Wandao New Material Technology Co., Ltd.

[0047] Steel fiber: Chengdu Keliang Building Materials Co., Ltd.

[0048] Polypropylene fiber: Shaanxi Jitai Huahe New Materials Technology Co., Ltd., diameter 31μm.

[0049] KH-791: CAS No. 5089-72-5, active ingredient content 98%.

[0050] Graphene: Lingshou County Jianshi Mineral Powder Factory, content is 99%. Specific embodiments

[0051] Preparation Example 1 This preparation example provides a titanium dioxide-loaded fiber, and the preparation method comprises the following steps: A1. Immerse the fiber in a 50℃, 0.5g / L Na2CO3 solution for 15min, then wash it three times with deionized water, then immerse it in 50℃ anhydrous ethanol and acetone solution for 10min each, and finally dry it in a 50℃ oven for later use; A2, tetrabutyl titanate was added dropwise to anhydrous ethanol and stirred, and then deionized water was added, the volume ratio of tetrabutyl titanate, anhydrous ethanol and deionized water was 1.5:23:130, the pretreated fiber in A1 was immersed for 20 minutes, and placed in a reactor together with the solution, and heated at 100°C for 2 hours, and then taken out and cooled to room temperature, and the fiber modified by titanium dioxide loading was repeatedly washed with deionized water until the solution was clear, and dried at 50°C; titanium dioxide loaded fiber was obtained. The fiber in this preparation example is steel fiber.

[0052] Preparation Example 2 The difference between this preparation example and the preparation example is that when preparing titanium dioxide loaded fibers in this preparation example, the preparation method includes the following steps: A1. Immerse the fiber in a 50℃, 0.5g / L Na2CO3 solution for 15min, then wash it three times with deionized water, then immerse it in 50℃ anhydrous ethanol and acetone solution for 10min each, and finally dry it in a 50℃ oven for later use; A2. Add tetrabutyl titanate dropwise into anhydrous ethanol and stir, then add deionized water, the volume ratio of tetrabutyl titanate, anhydrous ethanol and deionized water is 2:26:135, soak the fiber pretreated in A1 for 26 minutes, place it in a reactor together with the solution, heat it at a constant temperature of 120°C for 2 hours, then take it out and cool it to room temperature, wash the fiber modified by titanium dioxide loading with deionized water repeatedly until the solution is clear, and dry it at 50°C; titanium dioxide loaded fiber is obtained.

[0053] Preparation Example 3 The difference between this preparation example and the preparation example is that when preparing titanium dioxide loaded fibers in this preparation example, the preparation method includes the following steps: A1. Immerse the fiber in a 50℃, 0.5g / L Na2CO3 solution for 15min, then wash it three times with deionized water, then immerse it in 50℃ anhydrous ethanol and acetone solution for 10min each, and finally dry it in a 50℃ oven for later use; A2. Add tetrabutyl titanate dropwise into anhydrous ethanol and stir, then add deionized water, the volume ratio of tetrabutyl titanate, anhydrous ethanol and deionized water is 2.5:28:140, soak the fiber pretreated in A1 for 30 minutes, put it in a reactor together with the solution, heat it at a constant temperature of 130°C for 2 hours, then take it out and cool it to room temperature, wash the fiber modified by titanium dioxide loading with deionized water repeatedly until the solution is clear, and dry it at 50°C to obtain titanium dioxide loaded fiber.

[0054] Preparation Example 4 The difference between this preparation example and preparation example 2 is that, in this preparation example, when preparing titanium dioxide-loaded fibers, the fibers are compounded by steel fibers and polypropylene fibers in a weight ratio of 1:1.

[0055] Preparation Example 5 The difference between this preparation example and preparation example 4 is that in this preparation example, when preparing titanium dioxide loaded fibers, the titanium dioxide loaded fibers are replaced by KH-791 modified titanium dioxide loaded fibers. The preparation method is as follows: KH-791 is dissolved in ethanol, and the titanium dioxide loaded fibers prepared in preparation 2 are added and immersed for 2 hours, and the ethanol is removed and washed to obtain KH-791 modified titanium dioxide loaded fibers. The weight ratio of KH-791, ethanol and titanium dioxide loaded fibers is 1:30:5.

[0056] Preparation Example 6 The difference between this preparation example and preparation example 5 is that in this preparation example, when preparing titanium dioxide loaded fibers, KH-791 modified titanium dioxide loaded fibers are replaced by graphene-coated KH-791 modified titanium dioxide loaded fibers.

[0057] The preparation method of graphene-coated titanium dioxide-loaded modified fiber comprises the following steps: B1. Add titanium dioxide-loaded fibers to the acidic aqueous solution under constant stirring, mix evenly, heat to 80° C., keep warm for 9 hours, and cool to room temperature to obtain a mixture; B2. Under constant stirring, sodium hydroxide is added to the mixture, and the pH value is adjusted to 9, then nano-graphene oxide is added, mixed evenly, heated to 70°C, and kept warm for 2 hours, then polyethylene glycol is added, mixed evenly, and kept warm for 15 hours, cooled to room temperature, centrifuged, and air-dried to obtain graphene-coated titanium dioxide-loaded modified fibers; wherein the weight ratio of titanium dioxide-loaded fibers, nano-graphene oxide, acidic solution, and polyethylene glycol is 2.5:1.5:68:9; The acidic aqueous solution is a mixture of hydrochloric acid solution and sulfuric acid solution, the weight ratio of the hydrochloric acid solution to the sulfuric acid solution is 1:1, the mass concentration of the hydrochloric acid solution is 10%, and the mass solubility of the sulfuric acid solution is 23%.

[0058] Example 1 The present embodiment provides a CF120 ultra-high strength concrete, which includes the following raw materials by weight: 500 parts of cement; 750 parts of sand; 1200 parts of crushed stone; 90 parts of fly ash; 75 parts of straw ash; 37 parts of silica fume; 145 parts of water; 15 parts of water reducer; 15 parts of activator; 3 parts of defoamer; 12 parts of shrinkage reducer; 23 parts of CaCO3 whisker; 25 parts of polyvinyl alcohol formal; 25 parts of titanium dioxide loaded fiber; the fiber in the present embodiment is steel fiber. The titanium dioxide loaded fiber in the present embodiment is prepared by Preparation Example 1.

[0059] The water reducing agent in this embodiment is a high-efficiency polycarboxylate water reducing agent.

[0060] The cement in this embodiment is P·O52.5R grade ordinary Portland cement.

[0061] The particle size range of the crushed stone in this embodiment is 5mm-15mm.

[0062] The activator in this embodiment is prepared by mixing Na2SiO3·9H2O, Ca2SO4·2H2O and CaCl2, with a mass ratio of 11:4:1.5.

[0063] The defoamer in this embodiment is a polyacrylate defoamer.

[0064] The shrinkage reducing agent in this embodiment is a SU-SRA type shrinkage reducing agent.

[0065] The preparation method of CF120 ultra-high strength concrete in this embodiment includes the following steps: S1, the water is divided into three equal parts, the first part of the water is mixed with the water reducing agent to obtain the first mixed solution, and the second part of the water is mixed with the shrinkage reducing agent and the defoaming agent to obtain the second mixed solution; S2, cement, sand, crushed stone, fly ash, straw ash, silica fume, the third portion of water, and CaCO3 whiskers are mixed in order and placed in a pan mixer, and stirred for 1 minute; titanium dioxide-loaded fibers and polyvinyl alcohol acetal are then added, and stirred for 3 minutes; the first portion of the mixed solution prepared in step S1 is then added, and stirred for 4 minutes to prepare a third portion of the mixed solution; S3, adding an exciter to the third mixed solution, stirring evenly for 4 minutes, to obtain a fourth mixed solution; S4. Add the second mixed liquid to the fourth mixed liquid, stir for 3 minutes until the mixture is uniform, discharge the mixture to obtain a concrete mixture, shape and cure the concrete mixture to obtain CF120 ultra-high strength concrete.

[0066] The standard curing method is: pour the concrete mixture into a cast iron mold to form and vibrate it, let it stand for 2 days in a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95%, remove the mold, and then cure it in the standard curing room to the required age.

[0067] Example 2 The difference between this embodiment and embodiment 1 is that, when preparing CF120 ultra-high strength concrete, the weight ratio of polyvinyl formal and titanium dioxide loaded fiber is 0.8:1.

[0068] Example 3 The difference between this embodiment and embodiment 1 is that, when preparing CF120 ultra-high strength concrete, the weight ratio of polyvinyl formal to titanium dioxide loaded fiber is 1.1:1.

[0069] Example 4 The difference between this embodiment and embodiment 1 is that, when preparing CF120 ultra-high strength concrete, the weight ratio of polyvinyl formal to titanium dioxide loaded fiber is 1.2:1.

[0070] Comparative Examples 1-3 Comparative Example 1 The difference between this comparative example and Example 1 is that when preparing CF120 ultra-high strength concrete, an equal amount of polyvinyl formal is used to replace the titanium dioxide loaded fiber.

[0071] Comparative Example 2 The difference between this comparative example and Example 1 is that when preparing CF120 ultra-high strength concrete, an equal amount of titanium dioxide-loaded fibers is used to replace polyvinyl formal.

[0072] Comparative Example 3 The difference between this comparative example and Example 1 is that when preparing CF120 ultra-high strength concrete, an equal amount of fibers are used instead of titanium dioxide loaded fibers.

[0073] Experimental testing: 1. Compressive strength and flexural strength: According to GB / T500812019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete", the compressive strength and flexural strength of the samples are tested.

[0074] 2. Freeze-thaw cycle: According to GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete", freeze-thaw cycles are performed on the specimens, and the cracking conditions of the specimens before and after the freeze-thaw cycles are tested.

[0075] The experimental test results of Examples 1-4 and Comparative Examples 1-3 are shown in Table 1.

[0076] Table 1 - Experimental test results of Examples 1-4 and Comparative Examples 1-3 Example Compressive strength (28d) Flexural strength Before freeze-thaw cycle Freeze-thaw cycles 300 times Freeze-thaw cycles 600 times Example 1 124.3 38.81 No cracks No cracks There are cracks Example 2 123.5 36.20 No cracks No cracks There are cracks Example 3 123.9 37.81 No cracks No cracks There are cracks Example 4 123.7 37.53 No cracks No cracks There are cracks Comparative Example 1 112.6 34.90 No cracks No cracks There are cracks Comparative Example 2 116.9 30.11 There are cracks There are cracks There are cracks Comparative Example 3 113.2 29.03 There are cracks There are cracks There are cracks Result analysis: The difference between Examples 2-4 and Example 1 is that when preparing CF120 ultra-high-strength concrete, the weight ratio of polyvinyl alcohol acetal and titanium dioxide loaded fiber is different. Combined with the experimental test data in Table 1, it can be seen that when the weight ratio of polyvinyl alcohol acetal and titanium dioxide loaded fiber is 1:1, the comprehensive performance of the concrete obtained is better. The difference between Comparative Example 1 and Example 1 is that when preparing CF120 ultra-high-strength concrete, an equal amount of polyvinyl alcohol acetal is used to replace titanium dioxide loaded fiber. The difference between Comparative Example 2 and Example 1 is that when preparing CF120 ultra-high-strength concrete, an equal amount of titanium dioxide loaded fiber is used to replace polyvinyl alcohol acetal. Combined with the experimental test data in Table 1, it can be seen that when titanium dioxide loaded fiber and polyvinyl alcohol acetal are used simultaneously, it has a significant effect on the improvement of concrete compressive strength and crack resistance. The difference between Comparative Example 3 and Example 1 is that when preparing CF120 ultra-high-strength concrete, an equal amount of fiber is used to replace titanium dioxide loaded fiber. Combined with the experimental test data in Table 1, it can be seen that when titanium dioxide is used instead of loaded fibers, the compressive strength and crack resistance of concrete will be affected.

[0077] Embodiment 5-6 Example 5 The difference between this embodiment and embodiment 1 is that, when preparing CF120 ultra-high strength concrete, the weight fractions of some components are changed. The difference is shown in Table 2.

[0078] Table 2 - Differences between Example 5-6 and Example 3 Ingredients (portions) Example 1 Example 5 Example 6 cement 500 560 600 sand 750 800 860 gravel 1200 1320 1350 Fly ash 90 96 100 Straw ash 75 79 83 Silica Fume 37 42 50 water 145 150 160 Water reducing agent 15 17 20 Stimulant 15 18 20 Defoaming agent 3 4 5 Shrinkage Reducing Agent 12 14 16 CaCO3 Whiskers 23 25 28 Polyvinyl alcohol acetaldehyde 25 25 25 Titanium dioxide loaded fibers 25 25 25 The experimental test results of Examples 5-6 are shown in Table 3.

[0079] Table 3 - Experimental test results of Examples 5-6 Result analysis: The difference between Example 5-6 and Example 1 is that when preparing CF120 ultra-high strength concrete, the weight proportions of some components are different. Combined with the experimental test results in Table 3, it can be seen that the comprehensive performance of the CF120 ultra-high strength concrete prepared by Example 5 is better.

[0080] Embodiment 7-11 Example 7 The difference between Examples 7-11 and Example 5 is that when preparing CF120 ultra-high-strength concrete, on the premise that the weight ratio of polyvinyl alcohol acetaldehyde and titanium dioxide loaded fiber is 1:1, the total weight ratio of polyvinyl alcohol acetaldehyde and titanium dioxide loaded fiber in the CF120 ultra-high-strength concrete is changed, and the optimal weight ratio is selected.

[0081] In Example 5, the total weight of polyvinyl formal and titanium dioxide loaded fibers is 50 parts, and the total weight of CF120 ultra-high strength concrete is 3175 parts.

[0082] Therefore, it is not difficult to conclude that in Example 5, the proportion of polyvinyl formal (referred to as variable 1) and titanium dioxide loaded fiber (referred to as variable 2) in the CF120 ultra-high strength concrete (referred to as the matrix) is 1.57%.

[0083] The differences between Examples 7-11 and Example 5 are shown in Table 4.

[0084] Proportion = (variable 1 + variable 2) / total weight of matrix * 100%.

[0085] Table 4 - Differences between Examples 7-11 and Example 5 The experimental test results of Examples 7-11 are shown in Table 5.

[0086] Table 5 - Experimental test results of Examples 7-11 Result analysis: The difference between Example 7-11 and Example 5 is that when preparing CF120 ultra-high strength concrete, the total weight of polyvinyl alcohol acetal and titanium dioxide loaded fiber in CF120 ultra-high strength concrete accounts for different proportions. Combined with the experimental test results in Table 5, it can be seen that when the total weight of polyvinyl alcohol acetal and titanium dioxide loaded fiber in CF120 ultra-high strength concrete accounts for 1.5-1.8%, the comprehensive performance of the obtained CF120 ultra-high strength concrete is better, and when the total weight of polyvinyl alcohol acetal and titanium dioxide loaded fiber in CF120 ultra-high strength concrete accounts for 1.76%, the comprehensive performance of the obtained CF120 ultra-high strength concrete is the best. When the proportion is too high or too low, the comprehensive performance will decrease.

[0087] Examples 12-16 Example 12 The difference between this embodiment and embodiment 10 is that when preparing CF120 ultra-high strength concrete, different preparation parameters of the titanium dioxide loaded fibers are used. The titanium dioxide loaded fibers in this embodiment are prepared by Preparation Example 2.

[0088] Example 13 The difference between this embodiment and embodiment 10 is that, when preparing CF120 ultra-high strength concrete, the titanium dioxide loaded fiber in this embodiment is prepared by Preparation Example 3.

[0089] Embodiment 14 The difference between this embodiment and embodiment 10 is that, when preparing CF120 ultra-high strength concrete, the titanium dioxide loaded fiber provided in Preparation Example 4 is prepared by Preparation Example 4.

[0090] Embodiment 15 The difference between this embodiment and embodiment 10 is that, when preparing CF120 ultra-high strength concrete, the titanium dioxide loaded fiber in this embodiment is replaced by KH-791 modified titanium dioxide loaded fiber, and the KH-791 modified titanium dioxide loaded fiber is prepared by Preparation Example 5.

[0091] Example 16 The difference between this embodiment and embodiment 10 is that, when preparing CF120 ultra-high strength concrete, the KH-791 modified titanium dioxide loaded fiber in this embodiment is replaced by graphene-coated KH-791 modified titanium dioxide loaded fiber, and the graphene-coated KH-791 modified titanium dioxide loaded fiber is prepared by Preparation Example 6.

[0092] Table 6 - Experimental test results of Examples 12-16 Example Compressive strength (28d) Flexural strength Before freeze-thaw cycle Freeze-thaw cycles 300 times Freeze-thaw cycles 600 times Example 10 127.8 40.92 No cracks No cracks There are cracks Example 12 128.5 41.62 No cracks No cracks There are cracks Example 13 128.2 41.37 No cracks No cracks There are cracks Embodiment 14 129.7 42.71 No cracks No cracks There are cracks Embodiment 15 130.8 43.94 No cracks No cracks There are cracks Example 16 132.6 45.81 No cracks No cracks No cracks Result analysis: The difference between Examples 12-13 and Example 10 is that different preparation parameters of the titanium dioxide loaded fibers are used in preparing the CF120 ultra-high strength concrete. Combined with the experimental test results in Table 6, it can be seen that the CF120 ultra-high strength concrete prepared by Example 12 has better comprehensive performance.

[0093] The difference between Example 14 and Example 10 is that when preparing CF120 ultra-high strength concrete, the fibers are compounded from steel fibers and polypropylene fibers. Combined with the experimental test data in Table 6, it can be seen that the titanium dioxide-loaded fibers made from the compounded fibers can better improve the compressive strength of the prepared concrete.

[0094] The difference between Example 15 and Example 10 is that when preparing CF120 ultra-high strength concrete, the titanium dioxide loaded fiber in this embodiment is replaced by KH-791 modified titanium dioxide loaded fiber. It can be seen from the experimental test data in Table 6 that the titanium dioxide loaded fiber is modified by a coupling agent, which can further improve the compatibility and dispersibility with the concrete matrix, thereby being able to better improve its crack resistance and compressive strength. The reason may be that the titanium dioxide loaded fiber is modified by the KH-791 coupling agent, which can significantly improve the compatibility and dispersibility of the fiber and the concrete matrix, thereby enhancing the crack resistance and compressive strength of the concrete. This is mainly because the modification of KH-791 improves the interfacial bonding between the fiber and the concrete matrix, reduces interface defects, and improves the overall performance of the material.

[0095] The difference between Example 16 and Example 10 is that when preparing CF120 ultra-high strength concrete, the KH-791 modified titanium dioxide loaded fiber in this embodiment is replaced by graphene-coated KH-791 modified titanium dioxide loaded fiber. It can be seen from the experimental test data in Table 6 that the graphene coating of KH-791 modified titanium dioxide loaded fiber can improve its freeze-thaw cycle number well. The reason may be that the graphene coating of KH-791 modified titanium dioxide loaded fiber can effectively improve the freeze-thaw cycle number of concrete. The addition of graphene not only improves the strength and stability of the fiber, but also improves the thermal conductivity of concrete due to its excellent thermal conductivity, reduces the internal stress caused by temperature changes, and thus enhances the durability of concrete in a freeze-thaw environment.

[0096] In summary, by fine-tuning the fiber type, preparation parameters and modification methods, the various properties of CF120 ultra-high-strength concrete, including compressive strength, crack resistance, durability and environmental adaptability, can be significantly improved, providing the modern construction industry with a better-performing and more durable building material solution. These experimental results emphasize the key role of fiber modification technology in the development of high-performance concrete and open up new directions for the research and application of future building materials.

[0097] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A CF120 ultra-high strength concrete, characterized in that: The concrete comprises the following raw materials by weight: 500-600 parts of cement; Sand 750-860 parts; 1200-1350 parts of crushed stone; Fly ash 90-100 parts; Straw ash 75-83 parts; Silica fume 37-50 parts; 145-160 parts of water; 15-20 parts of water reducing agent; 15-20 parts of stimulant; 3-5 parts of defoaming agent; 12-16 parts of shrinkage reducing agent; 23-28 parts of CaCO3 whiskers; 20-30 parts of polyvinyl formal; 20-30 parts of titanium dioxide loaded fiber; The titanium dioxide loaded fiber is prepared by modifying the fiber with titanium dioxide; the fiber comprises at least one of steel fiber and polypropylene fiber.

2. The CF120 ultra-high strength concrete according to claim 1, characterized in that: The fiber is prepared by compounding steel fiber and polypropylene fiber in a weight ratio of 1:

1.

3. The CF120 ultra-high strength concrete according to claim 1, characterized in that: The titanium dioxide-loaded fiber is replaced by KH-791 modified titanium dioxide-loaded fiber.

4. The CF120 ultra-high strength concrete according to claim 3, characterized in that: The KH-791 modified titanium dioxide loaded fiber is replaced by graphene-coated KH-791 modified titanium dioxide loaded fiber.

5. The CF120 ultra-high strength concrete according to claim 1, characterized in that: The weight ratio of the polyvinyl formal to the titanium dioxide loaded fiber is (0.8-1):

1.

6. The CF120 ultra-high strength concrete according to claim 1, characterized in that: The weight ratio of the polyvinyl formal to the titanium dioxide-loaded fiber is 1:

1.

7. The CF120 ultra-high strength concrete according to claim 1, characterized in that: The total weight of the polyvinyl formal and the titanium dioxide loaded fibers accounts for 1.5-1.8% of the total weight of the CF120 ultra-high strength concrete.

8. The CF120 ultra-high strength concrete according to claim 1, characterized in that: The preparation method of the titanium dioxide loaded fiber comprises the following steps: A1. The fiber is immersed in a Na2CO3 solution, washed, immersed in anhydrous ethanol and acetone respectively, and dried to obtain a pretreated fiber; A2, adding tetrabutyl titanate dropwise into anhydrous ethanol and stirring, adding deionized water, the volume ratio of tetrabutyl titanate, anhydrous ethanol and deionized water is (1.5-2.5): (23-28): (130-140), and immersing the pretreated fiber in S1 for 20-30 minutes to obtain a fiber mixed solution; A3. Heat the fiber mixture in a reaction kettle at a constant temperature of 100-130° C. for 2-3 hours, then take it out and cool it to room temperature, wash it, and dry it to obtain the titanium dioxide loaded fiber.

9. The CF120 ultra-high strength concrete according to claim 4, characterized in that: The preparation method of the graphene-coated KH-791 modified titanium dioxide loaded fiber comprises the following steps: B1. Add KH-791 modified titanium dioxide loaded fiber to the acidic aqueous solution, mix evenly, heat to 7585° C., keep warm for 810 h, cool to room temperature, and obtain a mixture; B2. Add sodium hydroxide to the mixture and adjust the pH value to 89, then add nano graphene oxide, mix well, heat to 6070°C, keep warm for 45 hours, then add polyethylene glycol, mix well, continue to keep warm for 1215 hours, cool to room temperature, centrifuge, and air-dry to obtain the graphene-coated KH-791 modified titanium dioxide loaded fiber.

10. A method for preparing the CF120 ultra-high strength concrete according to claim 1, characterized in that: The preparation method comprises the following steps: S1, the water is divided into three equal parts, the first part of the water is mixed with the water reducing agent to obtain the first mixed solution, and the second part of the water is mixed with the shrinkage reducing agent and the defoaming agent to obtain the second mixed solution; S2, cement, sand, crushed stone, fly ash, straw ash, silica fume, the third portion of water, and CaCO3 whiskers are mixed in order and placed in a pan mixer, and stirred for 1 minute; titanium dioxide-loaded fibers and polyvinyl alcohol acetal are then added, and stirred for 2-4 minutes; the first portion of the mixed solution prepared in step S1 is then added, and stirred for 3-5 minutes to prepare a third portion of the mixed solution; S3, add the activator to the third mixed solution, stir evenly for 3-5 minutes, and obtain the fourth mixed solution; S4. Add the second mixed liquid to the fourth mixed liquid, stir for another 23 minutes until the mixture is uniform, discharge the mixture to obtain a concrete mixture, and shape and cure the concrete mixture to obtain the CF120 ultra-high strength concrete.

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