Ultra-high performance concrete and preparation method thereof

Abstract

The invention relates to the field of concrete, and particularly discloses ultra-high performance concrete and a preparation method thereof. The ultra-high performance concrete comprises the following components in parts by weight: 45-55 parts of Portland cement, 12-18 parts of silica fume, 12-18 parts of fine aggregate, 0.5-2 parts of a water reducing agent, 10-15 parts of water and 2-6 parts of reinforced fibers, wherein the fine aggregate is quartz sand with the particle size distribution of 0.2-2mm; the preparation method comprises the following steps: mixing and stirring the Portland cement, the silica fume and the fine aggregate, adding the water reducing agent and the water during stirring to obtain a concrete mixture, adding the reinforced fibers into the concrete mixture, and uniformly stirring; and pouring the concrete mixture into a mold, standing for 24 hours, carrying out steam curing on the concrete at the temperature of 40-50 DEG C and the humidity of 90-100% for 30-40 hours, demolding after the steam curing is completed, and carrying out natural curing for 10-15 days. The ultra-high performance concrete provided by the invention solves the problem of poor fluidity of ultra-high strength concrete.

Description

Technical Field

[0001] The present application relates to the field of concrete, and more specifically, to an ultra-high performance concrete and a preparation method thereof. Background Art

[0002] With the continuous development of modern construction technology, the performance requirements of concrete materials in construction projects are increasing. Although traditional concrete materials have certain strength and durability, they often show many limitations when facing some special engineering requirements. For example, in high-rise buildings, bridges, tunnels, nuclear power plants and other projects, traditional concrete is difficult to meet the requirements in terms of bearing capacity, crack resistance, durability, etc. In this case, it is particularly important to develop concrete materials with higher strength, better durability and better physical properties.

[0003] Ultra-High Performance Concrete (UHPC) has gradually attracted widespread attention as a new type of building material. Compared with traditional concrete, UHPC has higher compressive strength and tensile strength, usually reaching more than 120MPa or even higher. In addition, the density of UHPC in microstructure is significantly improved, so it has excellent impermeability, frost resistance and chemical corrosion resistance. These characteristics make UHPC have great application potential in extreme environments, such as high-cold areas, marine engineering, and special fields such as nuclear power plants.

[0004] Since ultra-high performance concrete uses a higher proportion of ultra-fine materials and a lower water-cement ratio in its formula design, the mixture has a higher viscosity. The high-viscosity UHPC mixture has poor fluidity and is difficult to evenly fill the formwork through traditional vibration methods, especially in complex structures. Concrete is prone to quality problems such as stratification and voids, which directly affect the strength and durability of the final structure. Secondly, the high viscosity of UHPC also places higher demands on pumping performance. Conventional pumping equipment and processes often cannot meet its transportation needs, further limiting the application of UHPC in large volumes and complex structures. Summary of the invention

[0005] In order to solve the problem of poor fluidity of ultra-high strength concrete, the present application provides an ultra-high performance concrete and a preparation method thereof.

[0006] The ultra-high performance concrete provided in this application adopts the following technical solution: An ultra-high performance concrete comprises, by weight, 45-55 parts of silicate cement, 12-18 parts of silica fume, 12-18 parts of fine aggregate, 0.5-2 parts of water reducer, 10-15 parts of water and 2-6 parts of reinforcing fiber, wherein the fine aggregate is quartz sand with a particle size distribution between 0.2 and 2 mm.

[0007] By adopting the above technical scheme, the present application optimizes the fluidity, density, strength and crack resistance of concrete as a whole by rationally proportioning each component. By controlling the addition amount of water reducer and water, the fluidity of concrete is significantly improved. The water reducer reduces the water demand in the mixture, and the appropriate amount of water allows the concrete to maintain fluidity while avoiding the bleeding caused by excessive fluidity, achieving a reasonable water-cement ratio in the concrete and ensuring that the concrete has good strength, density and durability. The combination of silicate cement and silica fume, combined with an appropriate amount of fine aggregate, significantly improves the matrix density of the concrete. The combined action of silica fume and quartz sand fills the micropores in the cement matrix and enhances the strength and durability of the concrete. The reinforcing fiber significantly improves the crack resistance of the concrete while ensuring the fluidity and strength of the concrete. The distribution of the fiber helps to prevent the development of cracks, giving the concrete higher tensile strength and toughness. It ensures that the concrete has good strength, density and durability.

[0008] Optionally, the water reducing agent component includes, by weight, 50-60 parts of methoxy polyethylene glycol methacrylate, 5-10 parts of graphene oxide, 5-15 parts of polyglutamic acid, 3-9 parts of sodium fluoride silicate, and 5-10 parts of fumed silica.

[0009] By adopting the above technical scheme, methoxy polyethylene glycol methacrylate is the main water reducing agent component, which can adsorb to the surface of cement particles through its long-chain molecular structure and side chain functional groups to form a stable hydration layer. At the same time, it can produce a steric hindrance effect on the surface of cement particles, prevent agglomeration between particles, and make the cement paste more uniform and more fluid. Graphene oxide has a two-dimensional sheet structure and can be dispersed in concrete to form a uniform nano-network structure. This structure helps to reduce the friction resistance in the mixture and enhance the fluidity of the cement paste. The addition of graphene oxide not only improves the fluidity of concrete, but also further optimizes the dispersion effect of cement particles due to its strong dispersibility, thereby reducing the viscosity of concrete and improving construction performance. The high water absorption of polyglutamic acid enables it to lock the free water in the mixture, forming a uniform water distribution, ensuring that the concrete has good fluidity during construction, especially under long-term transportation or high temperature conditions, it can effectively prevent the rapid water loss of concrete and maintain stable fluidity. Fumed silica reduces the gaps and friction between particles, further improving the fluidity of concrete. This water-reducing agent formula greatly improves the fluidity of concrete through a scientific and reasonable combination of components, allowing the concrete to maintain excellent construction performance under low water-cement ratio conditions and meet the engineering requirements of high fluidity and high strength.

[0010] Optionally, the water reducing agent further comprises 4-6 parts of a carboxylic acid-sulfonic acid copolymer.

[0011] By adopting the above technical solution, the carboxylic acid-sulfonic acid copolymer is an amphiphilic molecular structure that combines the advantages of carboxylic acid and sulfonic acid groups. The carboxylic acid part provides strong adsorption ability with the surface of cement particles to form a stable adsorption layer; the sulfonic acid group provides additional charge, so that the surface of cement particles carries more negative charge, further enhancing the electrostatic repulsion between particles. The carboxylic acid-sulfonic acid copolymer further enhances the dispersibility of cement particles through its dual action mechanism. This enhanced dispersion effect can further reduce the water demand of concrete, while maintaining good fluidity, ensuring the strength and density of concrete. Due to the addition of sulfonic acid groups, the electrostatic repulsion between cement particles increases, the agglomeration phenomenon between particles is reduced, and the viscosity of concrete paste is reduced, thereby significantly improving the fluidity of concrete. This effect is particularly obvious under low water-cement ratio conditions. The carboxylic acid-sulfonic acid copolymer also has good water retention capacity, which allows the concrete to maintain better fluidity during long-term construction, reduce bleeding and segregation, and improve construction operability and the surface quality of the final product.

[0012] Optionally, the reinforcing fiber is selected from one of steel fiber, glass fiber and polypropylene fiber.

[0013] By adopting the above technical solutions, steel fibers have extremely high strength and elastic modulus, which can effectively improve the tensile strength and toughness of concrete, resist the expansion of microcracks, and thus enhance the fracture toughness of concrete. This makes UHPC perform well in structural components with large forces and can better withstand loads. Glass fibers can improve the tensile strength and toughness of concrete, especially in structures that require high durability. The corrosion resistance of glass fibers also makes concrete more suitable for use in harsh environments. Polypropylene fibers can effectively inhibit early cracks caused by plastic shrinkage and shrinkage, thereby improving the overall durability of concrete. The addition of reinforcing fibers can form a multi-directionally distributed micro-network structure, which can more effectively disperse stress when concrete is under tension and prevent the formation and expansion of cracks.

[0014] Optionally, the length of the reinforcing fiber is 5-12 mm, the diameter of the reinforcing fiber is 0.2-0.3 mm, and the surface roughness Ra of the reinforcing fiber is 1.5-3.0 μm.

[0015] By adopting the above technical scheme, the length, diameter and surface roughness of the reinforcing fibers are selected so that when added to ultra-high strength concrete, the fibers can be evenly dispersed in the concrete matrix and have good bonding strength, thereby improving the tensile strength and toughness of the concrete, and the fluidity of the concrete will not be significantly affected, thereby ensuring the strength of the concrete while ensuring its fluidity.

[0016] Optionally, the particle gradation of the quartz sand by mass percentage is as follows: 0.2-0.6 mm fine particles account for 40%-50%, 0.6-1.2 mm medium particles account for 30%-40%, and 1.2-2.0 mm coarse particles account for 10%-30%.

[0017] By adopting the above technical solution, fine particles fill the gaps between medium and coarse particles, thereby improving the density of concrete. This gradation optimizes the arrangement between particles, reduces porosity, and improves the strength and durability of concrete. A higher proportion of fine particles and medium particles can provide sufficient lubrication and reduce friction between coarse particles, thereby improving the operability of concrete during construction. This optimized particle gradation can maintain good fluidity of concrete without significantly increasing the water-cement ratio. In addition, since this quartz sand gradation makes concrete more dense and reduces the gaps in the cement paste, the shrinkage caused by water evaporation is reduced. This helps to reduce the risk of cracking of concrete and improve its durability, especially in the early shrinkage stage, the optimized particle gradation can effectively inhibit the occurrence of plastic shrinkage cracks.

[0018] Optionally, the silica fume particle size distribution is 0.1-0.3 μm, and the silica fume specific surface area is 15-30 m 2 / g, the silica fume particles are spherical particles.

[0019] By adopting the above technical solution, ultrafine silica fume particles with a particle size of 0.1-0.3μm can well fill the larger pores in concrete, especially the gaps between cement particles. This fine filling effect significantly increases the density of concrete, thereby improving the compressive strength and anti-permeability of concrete. The specific surface area of ​​silica fume is 15-30m 2 / g, which means it has a large surface area and can react quickly with calcium hydroxide in cement to generate more calcium silicate hydrate. This volcanic ash reaction not only enhances the early strength of concrete, but also greatly improves its long-term durability. And the silica fume particles are spherical, which helps improve the fluidity and workability of concrete compared to conventional irregular or flaky silica fume.

[0020] In a second aspect, the present application provides a method for preparing ultra-high performance concrete, which adopts the following technical solution: A method for preparing ultra-high performance concrete, comprising the following steps: Mix and stir silicate cement, silica fume and fine aggregate, add water reducer and water during stirring, stir at a speed of 150-300r / min for 5-10min to obtain a concrete mixture, add reinforcing fiber to the concrete mixture and stir evenly; pour the concrete mixture into a mold, let it stand for 24h, steam cure the concrete at a temperature of 40-50℃ and a humidity of 90-100% for 30-40h, demold after completion, and then naturally cure for 15-20 days.

[0021] By adopting the above technical scheme, during the preparation process, silicate cement, silica fume and fine aggregate are mixed and stirred, and the fluidity and workability of concrete are optimized by water reducer. The stirring speed is controlled at 150-300r / min and lasts for 5-10 minutes to ensure that all components are fully mixed and avoid local inhomogeneity. This treatment method makes the concrete mixture more uniform and enhances the mechanical properties and stability of the final material. The 24-hour standing after pouring provides the initial setting time for the concrete, and then steam curing for 30-40 hours at 40-50℃ and 90-100% humidity can accelerate the cement hydration reaction. Steam curing under high temperature and high humidity conditions helps to generate more hydration products, especially calcium silicate hydrate (CSH), thereby improving the early strength and density of concrete. Steam curing not only promotes early strength development, but also reduces the capillaries in the concrete and reduces the porosity, thereby enhancing the concrete's anti-permeability, chemical corrosion resistance and freeze-thaw resistance. At the same time, steam curing can effectively reduce the formation of shrinkage cracks and improve the overall crack resistance of ultra-high performance concrete. After steam curing, 15-20 days of natural curing is carried out to further stabilize the microstructure of concrete, ensure that the hydration reaction is fully carried out, and avoid excessive accumulation of internal stress. Natural curing provides longer wet curing conditions, which is conducive to the continuous growth of concrete strength and the repair of microcracks, thereby ensuring the long-term stability of concrete during use.

[0022] In summary, this application has the following beneficial effects: 1. This application significantly optimizes the fluidity, density, strength and crack resistance of ultra-high performance concrete by finely proportioning silicate cement, silica fume, fine aggregate, water reducer, water and reinforcing fiber. The use of water reducer reduces water demand, maintains good fluidity and avoids water seepage, ensuring the high strength and durability of concrete. The combination of silica fume and quartz sand fills the micropores in the matrix, enhances density and strength, and the reinforcing fiber improves the crack resistance and toughness of concrete, giving it excellent tensile strength and durability.

[0023] 2. The water-reducing agent formula in this application preferably combines methoxy polyethylene glycol methacrylate, graphene oxide, polyglutamic acid, sodium fluoride silicate and fumed silica, which significantly improves the fluidity and construction performance of concrete. Methoxy polyethylene glycol methacrylate, as the main component, improves the uniformity and fluidity of cement paste through long-chain molecular structure and steric hindrance effect; graphene oxide and fumed silica increase the filling degree and fluidity of the paste; polyglutamic acid ensures that the concrete maintains moisture and fluidity stability under long-term transportation or high temperature conditions. Overall, the formula meets the high fluidity and high strength requirements of concrete under low water-cement ratio conditions. .

[0024] 3. The method of the present application first mixes the dry materials, and then uses a water reducer to optimize its fluidity and workability. Control the stirring speed at 150-300r / min, and stir for 5-10 minutes to ensure uniformity and improve mechanical properties. After pouring, let it stand for 24 hours to allow the concrete to initially solidify, and then steam cure it for 10-14 days at 40-50°C and 90-100% humidity to accelerate the hydration reaction and enhance early strength, density and impermeability. Steam curing reduces crack formation and improves crack resistance, followed by 10-15 days of natural curing to ensure the stability of the microstructure and further improve the strength and durability of the concrete. DETAILED DESCRIPTION

[0025] The present application is further described in detail below in conjunction with the examples. It is particularly noted that if no specific conditions are specified in the following examples, the experiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources.

[0026] Preparation example of water reducing agent Preparation Example 1 Preparation of water reducing agent: Prepare raw materials: purchased from Merck Chemicals, methoxy polyethylene glycol methacrylate (model 409529), polyglutamic acid (model P4761), fumed silica (model S5130); sodium fluorosilicate purchased from Shanghai McLean, density 2.68 g / mL at 25°C (lit.); graphene oxide purchased from Yeyuan Biotechnology (model S24800).

[0027] 5 kg of methoxy polyethylene glycol methacrylate was slowly added into 10 kg of 35° C. deionized water with a stirring speed of 400 rpm for 30 minutes to ensure that the methoxy polyethylene glycol methacrylate was completely dissolved to form a uniform solution.

[0028] Slowly add 0.5 kg of polyglutamic acid to the methoxy polyethylene glycol methacrylate solution while stirring at a high speed for 30 minutes, then add 0.3 kg of sodium fluoride silicate and keep stirring for 15 minutes.

[0029] 0.5 kg of graphene oxide and 0.5 kg of fumed silica were added to the dissolved methoxy polyethylene glycol methacrylate solution, and a high-speed shear mixer was used with the stirring speed controlled at 1800 rpm for 30 minutes to form a stable dispersion system.

[0030] After the stirring was completed, the mixture was allowed to stand for 16 hours for aging to obtain a water reducing agent.

[0031] Preparation Example 2 Preparation of water reducing agent: The difference from Preparation Example 1 is that the water reducing agent components are 6 kg of methoxy polyethylene glycol methacrylate, 1 kg of graphene oxide, 1.5 kg of polyglutamic acid, 0.9 kg of sodium fluoride silicate, and 1 kg of fumed silica.

[0032] Preparation Example 3 Preparation of water reducing agent: The difference from Preparation Example 1 is that the water reducing agent components are 5.5 kg of methoxy polyethylene glycol methacrylate, 0.8 kg of graphene oxide, 1 kg of polyglutamic acid, 0.6 kg of sodium fluoride silicate, and 0.7 kg of fumed silica.

[0033] Preparation Example 4 Preparation of water reducing agent: Prepare raw materials: purchased from Merck Chemical, methoxy polyethylene glycol methacrylate (model 409529), polyglutamic acid (model P4761), fumed silica (model S5130); sodium fluorosilicate purchased from Shanghai McLean, density 2.68g / mLat 25℃ (lit.); graphene oxide purchased from Yeyuan Bio (model S24800); carboxylic acid-sulfonic acid copolymer purchased from Shandong Taihe Technology (model TH-2000).

[0034] 5.5 kg of methoxy polyethylene glycol methacrylate was slowly added into 10 kg of 35° C. deionized water with a stirring speed of 400 rpm for 30 minutes to ensure that the methoxy polyethylene glycol methacrylate was completely dissolved to form a uniform solution.

[0035] Slowly add 1.0 kg of polyglutamic acid to the methoxy polyethylene glycol methacrylate solution while stirring at a high speed for 30 minutes, then add 0.6 kg of sodium fluorosilicate and 0.5 kg of carboxylic acid-sulfonic acid copolymer, and keep stirring for 15 minutes.

[0036] 0.8 kg of graphene oxide and 0.7 kg of fumed silica were added to the dissolved methoxy polyethylene glycol methacrylate solution, and a high-speed shear mixer was used with the stirring speed controlled at 1800 rpm for 30 minutes to form a stable dispersion system.

[0037] After the stirring was completed, the mixture was allowed to stand for 16 hours for aging to obtain a water reducing agent. Example

[0038] Example 1 A method for preparing ultra-high performance concrete: Raw materials preparation: PI type 62.5 grade Portland cement; Silica fume, purity ≥95%, particle size distribution 0.1-0.3μm, specific surface area 15-30m 2 / g, the particle shape is spherical particles; the fine aggregate is quartz sand, the purity is ≥99%, the particle size distribution is 0.2-2mm, 0.2-0.6mm fine particles account for 45%, 0.6-1.2mm medium particles account for 35%, and 1.2-2.0mm coarse particles account for 20%; The water reducing agent was prepared as in Preparation Example 1, purified water; The reinforcing fiber is copper-plated microfilament steel fiber purchased from Shandong Kaiwei New Materials Co., Ltd. The fiber length is 8±2mm, the diameter is 0.25±0.05mm, and the average surface roughness Ra is 2.2±0.5μm.

[0039] Pour 50kg of Portland cement, 15kg of silica fume and 15kg of fine aggregate into a mixer and dry mix them at a speed of 200r / min for 3 minutes. After the dry mixing is completed, gradually add 12kg of water and 1.2kg of water reducer. The speed of the mixer should be controlled at 200r / min and the mixing time is 10 minutes to obtain a concrete mixture.

[0040] Add 4kg of reinforcing fiber to the concrete mixture at a uniform speed, stirring as you add. Add the reinforcing fiber within 5±1min, and continue stirring for 5min after the addition is complete.

[0041] Pour the stirred concrete mixture into the pre-prepared mold, and vibrate it to make the mixture fill the mold evenly and remove internal bubbles. After vibration, let the concrete in the mold stand at room temperature for 24 hours to allow it to harden initially.

[0042] After standing for 24 hours, place the mold together with the concrete in a steam curing room. The curing environment is controlled at a temperature of 45±2°C and a humidity of 95±2%. The steam curing time is 36 hours.

[0043] After steam curing, the concrete is demoulded and placed in an outdoor natural curing environment for 18 days of natural curing. During the curing period, wet sacks are covered to keep the surface moist. After the natural curing period, ultra-high performance concrete is obtained.

[0044] Example 2 A method for preparing ultra-high performance concrete: The difference from Example 1 is that the ultra-high performance concrete components are 45 kg of silicate cement, 12 kg of silica fume, 12 kg of fine aggregate, 0.5 kg of water reducer, 10 kg of water and 2 kg of reinforcing fiber.

[0045] Example 3 A method for preparing ultra-high performance concrete: The difference from Example 1 is that the ultra-high performance concrete components are 55 kg of silicate cement, 18 kg of silica fume, 18 kg of fine aggregate, 2 kg of water reducer, 15 kg of water and 6 kg of reinforcing fiber.

[0046] Example 4 A method for preparing ultra-high performance concrete: The difference from Example 1 is that the water reducing agent is prepared by Preparation Example 2.

[0047] Example 5 A method for preparing ultra-high performance concrete: The difference from Example 1 is that the water reducing agent is prepared by Preparation Example 3.

[0048] Example 6 A method for preparing ultra-high performance concrete: The difference from Example 1 is that the water reducing agent is prepared by Preparation Example 4.

[0049] Example 7 A method for preparing ultra-high performance concrete: The difference from Example 1 is that the glass fiber is purchased from Chaobo Engineering Materials Co., Ltd., the fiber length is 8±2 mm, the diameter is 0.25±0.05 mm, and the average surface roughness Ra is 2.2±0.5 μm.

[0050] Example 8 A method for preparing ultra-high performance concrete: The difference from Example 1 is that the polypropylene fiber is purchased from Yue Rui Engineering Materials Co., Ltd., the fiber length is 8±2 mm, the diameter is 0.25±0.05 mm, and the average surface roughness Ra is 2.2±0.5 μm.

[0051] Comparative Example Comparative Example 1 A method for preparing ultra-high performance concrete: The difference from Example 1 is that the water reducer is TXHG-008 polycarboxylate water reducer produced by Tianxiang Chemical Co., Ltd.

[0052] Comparative Example 2 A method for preparing ultra-high performance concrete: the difference from Example 1 is that the fine aggregate is quartz sand with a purity of ≥99% and a particle size distribution of 0.2-2 mm, wherein 0.2-0.6 mm fine particles account for 20%, 0.6-1.2 mm medium particles account for 35%, and 1.2-2.0 mm coarse particles account for 45%; Comparative Example 3 A method for preparing ultra-high performance concrete: The difference from Example 1 is that the silica fume is selected to have a needle-shaped particle shape and is purchased from Hezhen Industrial Co., Ltd.

[0053] Comparative Example 4 A method for preparing ultra-high performance concrete: The difference from Example 1 is that the steel fiber length is 15 mm, the diameter is 0.4 mm, and the surface roughness Ra of the reinforcing fiber is 4 μm.

[0054] Performance testing Detection Methods The compressive strength of concrete is tested according to the method specified in the "Concrete Strength Test and Assessment Standard" (GB / T 50107-2010), and the compressive strength of concrete is tested after curing.

[0055] The toughness test was carried out according to the method specified in the national standard "Test method for fracture toughness of concrete" (GB / T 15734-2008).

[0056] The slump is tested according to the method specified in "Test Method for Performance of Ordinary Concrete Mixtures" (GB / T 50080-2002) to reflect the fluidity of concrete.

[0057] Table 1 Test data It can be seen from Example 1 and Comparative Example 1 and Table 1 that conventional polycarboxylate water reducers adsorb cement particles through the main chain, and the side chains play a steric hindrance effect, which can effectively improve the initial fluidity of concrete. However, its effect is easily weakened under long-term action or high temperature conditions, especially in long-distance transportation or summer construction, concrete is prone to fluidity loss. The addition of polyglutamic acid and graphene oxide in the water reducer formula of the present application not only improves the dispersion effect of cement particles, but also maintains the fluidity of concrete for a long time, which is particularly suitable for projects that need to maintain fluidity for a long time. The nano-network structure formed by the two-dimensional sheet structure of graphene oxide in concrete enables the water reducer to optimize the dispersion and fluidity of cement particles to a greater extent, and this advantage is particularly significant in ultra-high strength concrete. Conventional polycarboxylate water reducers cannot provide this enhancement effect, so they perform poorly when dealing with high-strength, high-performance concrete. Fumed silica significantly reduces the friction between concrete particles, which makes concrete have better fluidity.

[0058] It can be seen from Example 1 and Comparative Example 2 and Table 1 that fine particles fill the gaps between medium and coarse particles, thereby improving the density of concrete. This gradation optimizes the arrangement between particles, reduces porosity, and improves the strength and durability of concrete. A higher proportion of fine particles and medium particles can provide sufficient lubrication, reduce friction between coarse particles, and thus improve the operability of concrete during construction. This optimized particle gradation can maintain good fluidity of concrete without significantly increasing the water-cement ratio. In addition, since this quartz sand gradation makes the concrete more compact, the gaps in the cement slurry are reduced, thereby reducing the shrinkage caused by water evaporation.

[0059] It can be seen from Example 1 and Comparative Example 3 and Table 1 that the silica fume particles are spherical. Compared with conventional silica fume with irregular or flaky structures, this particle shape helps to improve the fluidity and workability of concrete.

[0060] It can be seen from Example 1 and Comparative Example 4 and Table 1 that the selection of the length, diameter and surface roughness of the reinforcing fibers enables the addition of the reinforcing fibers to the ultra-high strength concrete to ensure that the fibers are evenly dispersed in the concrete matrix and have good bonding strength, thereby improving the tensile strength and toughness of the concrete, and the fluidity of the concrete will not be significantly affected, thereby ensuring the strength of the concrete while ensuring its fluidity.

[0061] It can be seen from Examples 1-3 and Table 1 that the present application significantly optimizes the fluidity, density, strength and crack resistance of ultra-high performance concrete by finely proportioning silicate cement, silica fume, fine aggregate, water reducer, water and reinforcing fiber. The use of water reducer reduces water demand, maintains good fluidity and avoids water seepage, ensuring the high strength and durability of concrete. The combination of silica fume and quartz sand fills the micropores in the matrix, enhances density and strength, and the reinforcing fiber improves the crack resistance and toughness of the concrete, giving it excellent tensile strength and durability.

[0062] It can be seen from Example 1 and Examples 4-6 and Table 1 that the water reducing agent of the present application significantly improves the fluidity of concrete, especially under low water-cement ratio conditions. In addition, the carboxylic acid-sulfonic acid copolymer further enhances the dispersibility of cement particles through its dual action mechanism. This enhanced dispersion effect can further reduce the water demand of concrete, while maintaining good fluidity, ensuring the strength and density of concrete.

[0063] It can be seen from Example 1 and Examples 7-8 and Table 1 that the three reinforcing fibers selected in the present application can all achieve the effect of improving the toughness of concrete, and their addition will not cause a significant impact on the fluidity of concrete.

[0064] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. An ultra-high performance concrete, It is characterized in that The components thereof include 45-55 parts by weight of silicate cement, 12-18 parts of silica fume, 12-18 parts of fine aggregate, 0.5-2 parts of water reducing agent, 10-15 parts of water and 2-6 parts of reinforcing fiber. The fine aggregate is quartz sand with a particle size distribution between 0.2 and 2 mm.

2. The ultra-high performance concrete according to claim 1, Features: The water reducing agent components include, by weight, 50-60 parts of methoxy polyethylene glycol methacrylate, 5-10 parts of graphene oxide, 5-15 parts of polyglutamic acid, 3-9 parts of sodium fluoride silicate, and 5-10 parts of fumed silica.

3. The ultra-high performance concrete according to claim 2, Features: The water reducing agent also includes 4-6 parts of a carboxylic acid-sulfonic acid copolymer.

4. The ultra-high performance concrete according to claim 1, Features: The reinforcing fiber is selected from one of steel fiber, glass fiber and polypropylene fiber.

5. The ultra-high performance concrete according to claim 4, Features: The length of the reinforcing fiber is 5-12 mm, the diameter of the reinforcing fiber is 0.2-0.3 mm, and the surface roughness Ra of the reinforcing fiber is 1.5-3.0 μm.

6. The ultra-high performance concrete according to claim 1, Features: The particle gradation of the quartz sand by mass percentage is as follows: 0.2-0.6 mm fine particles account for 40%-50%, 0.6-1.2 mm medium particles account for 30%-40%, and 1.2-2.0 mm coarse particles account for 10%-30%.

7. The ultra-high performance concrete according to claim 1, Features: The silica fume particle size distribution is 0.1-0.3 μm, and the silica fume specific surface area is 15-30 m 2 / g, the silica fume particles are spherical particles.

8. A method for preparing ultra-high performance concrete according to any one of claims 1 to 7, Features: The following steps are involved: Mix and stir silicate cement, silica fume and fine aggregate, add water reducer and water during stirring, stir at a speed of 150-300 r / min for 5-10 minutes to obtain a concrete mixture, add reinforcing fiber to the concrete mixture and stir evenly; Pour the concrete mixture into the mold, let it stand for 24 hours, then steam cure the concrete at a temperature of 40-50℃ and a humidity of 90-100% for 30-40 hours. After completion, demould it and carry out natural curing for 15-20 days.

Images