An ultra-high performance concrete material for bridge structure and a preparation method and application thereof

Abstract

This invention discloses an ultra-high performance concrete material for bridge structures, its preparation method, and its applications, particularly relating to the field of concrete. The ultra-high performance concrete material for bridge structures of this invention comprises the following raw materials in parts by weight: 230-240 parts cement, 140-150 parts fly ash, 50-60 parts silica fume, 250-260 parts fine aggregate, 50-60 parts coarse aggregate, 5-9 parts water-reducing agent, 80-90 parts steel fiber, 0.03-0.08 parts modified graphene, 3-5 parts expansion agent, 1-3 parts viscosity modifier, and 70-80 parts water. The ultra-high performance concrete material for bridge structures prepared by this invention not only improves the viscosity of ultra-high performance concrete but also simultaneously enhances its compressive strength, flexural strength, and tensile strength, expanding its application prospects in bridge concrete.

Description

Technical Field

[0001] This invention relates to the field of concrete, and more particularly to an ultra-high performance concrete material for bridge structures, its preparation method, and its application. Background Technology

[0002] With the increasing demands on material performance in modern bridge engineering, ultra-high performance concrete (UHPC), a novel cement-based composite material, has attracted significant attention due to its superior mechanical properties, high toughness, and ultra-long durability. Compared to ordinary concrete, UHPC significantly enhances the deformation capacity and mechanical strength of concrete by incorporating components such as silica fume, fly ash, and steel fibers. This expands its application in bridge structures, substantially improving the load-bearing capacity of bridges, thereby extending their service life and reducing maintenance costs.

[0003] However, ultra-high performance concrete (UHPC) has a very low water-cement ratio, which increases its viscosity. This not only makes construction processes such as mixing, pouring, and vibration difficult, reducing construction efficiency, but also seriously affects the internal stress generated during the hardening process, increasing the risk of cracking and impacting its overall performance. To address these shortcomings in the application of UHPC in bridge structures, traditional high-performance concrete mainly reduces the initial viscosity of UHPC by optimizing the proportions of raw materials such as cement and silica fume. However, the mechanical strength of the concrete is usually not considered, limiting its service life and quality in bridge applications. Furthermore, existing high-performance concrete often uses multiphase mixed systems, and the density differences between components such as cement and aggregates can lead to a decrease in the homogeneity and density of the concrete, ultimately resulting in poorer mechanical properties and affecting its application in bridges.

[0004] Therefore, for UHPC materials used in bridge structures, it is necessary to develop a new type of concrete material with a new raw material formulation that can improve the initial viscosity of the concrete while enhancing its flexural strength and tensile strength, thereby improving the overall performance of the material and meeting the needs of bridge engineering for high-performance concrete materials. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide an ultra-high performance concrete material for bridge structures. This material can not only effectively improve the initial viscosity of concrete, but also enhance its compressive strength, flexural strength, and tensile strength, thereby improving the overall performance of the material and meeting the needs of bridge engineering for high-performance concrete materials.

[0006] The second objective of this invention is to provide a method for preparing ultra-high performance concrete materials for bridge structures. This method is relatively simple, helps to improve construction efficiency, and is suitable for industrial production.

[0007] The third objective of this invention is to provide an application of ultra-high performance concrete material for bridge structures, especially in bridges and high-rise buildings.

[0008] One of the objectives of this invention is achieved through the following technical solution:

[0009] An ultra-high performance concrete material for bridge structures comprises the following raw materials in parts by weight: 230-240 parts cement, 140-150 parts fly ash, 50-60 parts silica fume, 250-260 parts fine aggregate, 50-60 parts coarse aggregate, 5-9 parts water-reducing agent, 80-90 parts steel fiber, 0.03-0.08 parts modified graphene, 3-5 parts expansion agent, 1-3 parts viscosity modifier, and 70-80 parts water.

[0010] Furthermore, the preparation process of the modified graphene is as follows: graphene is added to a solvent, then isopropyl tris(isostearoyl) titanate and 2,2-bis[(4-trimethylsiloxy)phenyl]propane are added, and the mixture is heated and stirred to obtain modified graphene.

[0011] Further, the mass ratio of graphene, isopropyltris(isostearoyl)titanate and 2,2-bis[(4-trimethylsiloxy)phenyl]propane is 1:(3~5):(7~10), and the ratio of graphene to solvent is 1 g:80~100 mL; the solvent is N,N-dimethylformamide.

[0012] Furthermore, the heating and stirring temperature is 80~100℃, and the time is 2~5h.

[0013] This invention introduces modified graphene into ultra-high performance concrete, resulting in modified graphene with good compatibility with the cement gel matrix. Specifically, the graphene surface is modified with a titanate coupling agent (isopropyltris(isostearoyl)titanate), which increases the number of active groups, improving the compatibility between graphene and other substances. The introduced siloxy-containing compound (2,2-bis[(4-trimethylsiloxy)phenyl]propane) further modifies the graphene surface, altering its surface energy and reducing agglomeration. Furthermore, the long-chain entanglement of isopropyltris(isostearoyl)titanate and 2,2-bis[(4-trimethylsiloxy)phenyl]propane forms a cross-linked structure with graphene, improving the compactness of the concrete material. This interaction with cement and other components forms a denser structure, resulting in a tightly packed concrete system that enhances the compressive strength and stability of the concrete material.

[0014] Furthermore, the preparation process of the viscosity modifier is as follows: carboxymethyl cellulose, potassium hydroxide and urea are added to water, stirred at room temperature, and then frozen to obtain the viscosity modifier.

[0015] Further, the mass ratio of potassium hydroxide, urea, water and carboxymethyl cellulose is 5:(8~12):(95~100):(3~5).

[0016] Furthermore, the stirring time is 40~60 min; the freezing temperature is -30~-50℃, and the freezing time is 12~24 h.

[0017] This invention introduces a viscosity modifier, specifically a viscosity modifier prepared by the interaction of carboxymethyl cellulose with potassium hydroxide and urea. The addition of potassium hydroxide and urea helps to break the hydrogen bonds between cellulose molecules. Simultaneously, this viscosity modifier can reduce the cohesion of the concrete system by disrupting the flocculation structure between cement particles, thereby adjusting the fluidity of the concrete slurry, improving the viscosity of the concrete, making the components in the concrete easier to mix evenly, reducing the defects of agglomeration in the concrete material, and maintaining high mechanical properties of the concrete material.

[0018] Further, the fine aggregate is quartz sand or river sand with a particle size of 0.08~2mm; the coarse aggregate is one or more of limestone, basalt, or pebbles with a particle size of 5~12mm; the water-reducing agent is a powdered polycarboxylate high-performance water-reducing agent with a solid content greater than 40%; the expanding agent is a magnesium oxide-based or calcium sulfoaluminate-based expanding agent; the steel fiber is copper-plated steel fiber with a diameter of 0.1~0.3mm and a length of 10~15mm; the fly ash is low-calcium fly ash with a particle size of 5~10µm and a density of 2~3g / cm³. 3 The mass content of SiO2 is ≥40%; the silica fume is fully densified silica fume, and the mass content of SiO2 in the silica fume is ≥95%.

[0019] The second objective of this invention is achieved by the following technical solution:

[0020] The preparation method of the above-mentioned ultra-high performance concrete material for bridge structures includes the following steps:

[0021] (1) Weigh each raw material component according to the stated weight proportions and set aside;

[0022] (2) Cement, fly ash, silica fume, fine aggregate, coarse aggregate and expansion agent are mixed to obtain the first mixture;

[0023] (3) Add water-reducing agent, viscosity modifier and water to the first mixture and stir. Then add steel fiber and modified graphene and continue stirring to obtain the second mixture.

[0024] (4) The second mixture is poured into the mold, cured and then demolded to obtain ultra-high performance concrete.

[0025] Furthermore, the temperature for curing is 18~22℃, and the humidity is above 94%.

[0026] The third objective of this invention is achieved by the following technical solution:

[0027] The above-mentioned ultra-high performance concrete material for bridge structures is used in the preparation of bridge structural materials.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. This invention provides an ultra-high performance concrete material for bridge structures. Based on a cementitious system of cement, fly ash, and silica fume, this invention introduces modified graphene and a viscosity modifier, resulting in uniform distribution of each component and an overall homogeneous and dense concrete system. This improves the viscosity of ultra-high performance concrete while enhancing its compressive strength, flexural strength, tensile strength, and other properties, effectively ensuring its application in bridge structure reinforcement and extending its service life in bridge operations.

[0030] 2. The present invention also provides a method for preparing the above-mentioned ultra-high performance concrete material for bridge structures. The method is relatively simple, easy to construct, and suitable for industrial production and widespread application. Detailed Implementation

[0031] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments shall be performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0032] The fine aggregate of this invention is quartz sand or river sand with a particle size of 0.08-2 mm;

[0033] The coarse aggregate is one or more of limestone, basalt or pebbles, with a particle size of 5-12mm;

[0034] The water-reducing agent is a powdered polycarboxylate high-performance water-reducing agent with a solid content greater than 40%.

[0035] The expanding agent is a magnesium oxide-based or calcium sulfoaluminate-based expanding agent;

[0036] The steel fibers are copper-plated steel fibers with a diameter of 0.1-0.3 mm and a length of 10-15 mm.

[0037] The cement is high aluminate cement;

[0038] The fly ash is low-calcium fly ash with a particle size of 5-10µm and a density of 2-3g / cm³. 3The mass content of SiO2 is ≥40%;

[0039] The silica fume is fully encrypted silica fume, and the mass content of SiO2 in the silica fume is ≥95%.

[0040] Example 1

[0041] This embodiment provides an ultra-high performance concrete material for bridge structures, comprising the following raw materials in parts by weight: 235 parts cement, 145 parts fly ash, 55 parts silica fume, 255 parts fine aggregate (quartz sand), 55 parts coarse aggregate (limestone), 7 parts water-reducing agent, 85 parts steel fiber, 0.05 parts modified graphene, 4 parts expansion agent (magnesium oxide expansion agent), 2 parts viscosity modifier, and 75 parts water.

[0042] The preparation process of the modified graphene is as follows: Graphene, isopropyl tris(isostearoyl) titanate, and 2,2-bis[(4-trimethylsiloxy)phenyl]propane are weighed in a mass ratio of 1:4:9 and set aside. First, graphene is added to N,N-dimethylformamide for ultrasonic dispersion, and then isopropyl tris(isostearoyl) titanate and 2,2-bis[(4-trimethylsiloxy)phenyl]propane are added. The mixture is stirred at 90°C for 3 hours. The reaction solution is filtered, and the filter residue is washed and dried to obtain modified graphene.

[0043] The viscosity modifier is prepared as follows: Carboxymethyl cellulose, potassium hydroxide and urea are added to deionized water, wherein the mass ratio of potassium hydroxide, urea, deionized water and carboxymethyl cellulose is 5:8:100:5; the mixture is stirred at room temperature for 50 min and then frozen at -40℃ for 18 h to obtain the viscosity modifier.

[0044] This embodiment also provides a method for preparing the above-mentioned ultra-high performance concrete material for bridge structures, including the following steps:

[0045] (1) Weigh each raw material component according to the above weight proportions and set aside;

[0046] (2) Cement, fly ash, silica fume, fine aggregate, coarse aggregate and expansion agent are mixed to obtain the first mixture;

[0047] (3) Add water-reducing agent, viscosity modifier and water to the first mixture and stir. Then add steel fiber and modified graphene and continue stirring to obtain the second mixture.

[0048] (4) Pour the second mixture into the mold, place it in the curing room for 28 days and then demold it. The temperature of the curing room is 20℃ and the humidity is above 94% to obtain ultra-high performance concrete.

[0049] Example 2

[0050] This embodiment provides an ultra-high performance concrete material for bridge structures, comprising the following raw materials in parts by weight: 230 parts cement, 140 parts fly ash, 50 parts silica fume, 250 parts fine aggregate (river sand), 50 parts coarse aggregate (basalt), 5 parts water-reducing agent, 80 parts steel fiber, 0.03 parts modified graphene, 3 parts expansion agent (calcium sulfoaluminate expansion agent), 1 part viscosity modifier, and 70 parts water.

[0051] The preparation process of the modified graphene is as follows: Graphene, isopropyl tris(isostearoyl) titanate, and 2,2-bis[(4-trimethylsiloxy)phenyl]propane are weighed in a mass ratio of 1:3:7 and set aside. First, graphene is added to N,N-dimethylformamide for ultrasonic dispersion, and then isopropyl tris(isostearoyl) titanate and 2,2-bis[(4-trimethylsiloxy)phenyl]propane are added. The mixture is stirred at 80°C for 5 hours. The reaction solution is filtered, and the filter residue is washed and dried to obtain the modified graphene.

[0052] The viscosity modifier is prepared as follows: Carboxymethyl cellulose, potassium hydroxide and urea are added to deionized water, wherein the mass ratio of potassium hydroxide, urea, deionized water and carboxymethyl cellulose is 5:8:100:3; the mixture is stirred at room temperature for 40 min and then frozen at -30℃ for 24 h to obtain the viscosity modifier.

[0053] This embodiment also provides a method for preparing the above-mentioned ultra-high performance concrete material for bridge structures, including the following steps:

[0054] (1) Weigh each raw material component according to the above weight proportions and set aside;

[0055] (2) Cement, fly ash, silica fume, fine aggregate, coarse aggregate and expansion agent are mixed to obtain the first mixture;

[0056] (3) Add water-reducing agent, viscosity modifier and water to the first mixture and stir. Then add steel fiber and modified graphene and continue stirring to obtain the second mixture.

[0057] (4) Pour the second mixture into the mold, place it in the curing room for 28 days and then demold it. The temperature of the curing room is 18℃ and the humidity is above 94% to obtain ultra-high performance concrete.

[0058] Example 3

[0059] This embodiment provides an ultra-high performance concrete material for bridge structures, comprising the following raw materials in parts by weight: 240 parts cement, 150 parts fly ash, 60 parts silica fume, 260 parts fine aggregate (quartz sand), 60 parts coarse aggregate (pebbles), 9 parts water-reducing agent, 90 parts steel fiber, 0.08 parts modified graphene, 5 parts expansion agent (magnesium oxide expansion agent), 3 parts viscosity modifier, and 80 parts water.

[0060] The preparation process of the modified graphene is as follows: Graphene, isopropyl tris(isostearoyl) titanate, and 2,2-bis[(4-trimethylsiloxy)phenyl]propane are weighed in a mass ratio of 1:5:10 and set aside. First, graphene is added to N,N-dimethylformamide for ultrasonic dispersion, and then isopropyl tris(isostearoyl) titanate and 2,2-bis[(4-trimethylsiloxy)phenyl]propane are added. The mixture is stirred at 100°C for 2 hours. The reaction solution is filtered, and the filter residue is washed and dried to obtain the modified graphene.

[0061] The viscosity modifier is prepared as follows: Carboxymethyl cellulose, potassium hydroxide and urea are added to deionized water, wherein the mass ratio of potassium hydroxide, urea, deionized water and carboxymethyl cellulose is 5:8:100:4; the mixture is stirred at room temperature for 60 min and then frozen at -50℃ for 15 h to obtain the viscosity modifier.

[0062] This embodiment also provides a method for preparing the above-mentioned ultra-high performance concrete material for bridge structures, including the following steps:

[0063] (1) Weigh each raw material component according to the above weight proportions and set aside;

[0064] (2) Cement, fly ash, silica fume, fine aggregate, coarse aggregate and expansion agent are mixed to obtain the first mixture;

[0065] (3) Add water-reducing agent, viscosity modifier and water to the first mixture and stir. Then add steel fiber and modified graphene and continue stirring to obtain the second mixture.

[0066] (4) Pour the second mixture into the mold, place it in the curing room for 28 days and then demold it. The temperature of the curing room is 22℃ and the humidity is above 94% to obtain ultra-high performance concrete.

[0067] Comparative Example 1

[0068] Comparative Example 1 is basically the same as Example 1, except that the modified graphene is replaced with graphene, while the rest is the same as Example 1.

[0069] Comparative Example 2

[0070] Comparative Example 2 is basically the same as Example 1, except that isopropyl tris(isostearoyl) titanate is omitted in the preparation of modified graphene, while the rest is consistent with Example 1.

[0071] Comparative Example 3

[0072] Comparative Example 3 is basically the same as Example 1, except that 2,2-bis[(4-trimethylsiloxy)phenyl]propane is omitted in the preparation of modified graphene, while the rest is consistent with Example 1.

[0073] Comparative Example 4

[0074] Comparative Example 4 is basically the same as Example 1, except that the viscosity modifier is replaced with carboxymethyl cellulose, while the rest is the same as Example 1.

[0075] Experimental Example 1

[0076] According to the national standard GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", the compressive strength, elastic modulus, flexural strength and splitting tensile strength of the samples obtained in Examples 1-3 and Comparative Examples 1-4 were tested; the viscosity of the samples obtained in Examples 1-3 and Comparative Examples 1-4 was tested using a rheometer, and the test results are shown in Table 1.

[0077] Table 1 Performance Test Results

[0078]

[0079] As can be seen from the test results in Table 1, the viscosity, compressive strength, elastic modulus, flexural strength, and splitting tensile strength of Examples 1-3 are all higher than those of Comparative Examples 1-4. This is because the present invention optimizes the composition of concrete. The introduced modified graphene and cement gel matrix have good compatibility, which can improve the compactness of concrete materials and interact with cement to form a dense structure. The entire concrete system is tightly packed, improving the compressive strength, stability, and other properties of concrete materials. The viscosity modifier can adjust the fluidity of concrete slurry, thereby effectively reducing the viscosity of concrete and making it easier to mix the components in the concrete evenly, maintaining the uniformity and compactness of the concrete. This eliminates the generation and propagation of cracks in concrete caused by viscosity issues, thereby improving the overall performance of the bridge. The above results show that the introduction of modified graphene and viscosity modifier in this application not only improves the viscosity of ultra-high performance concrete, but also simultaneously improves its compressive strength, flexural strength, tensile strength, and other properties, expanding its application prospects in bridge concrete.

[0080] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. An ultra-high performance concrete material for bridge structures, characterized by, The raw materials include cement 230-240 parts by weight, fly ash 140-150 parts by weight, silica ash 50-60 parts by weight, fine aggregate 250-260 parts by weight, coarse aggregate 50-60 parts by weight, water reducing agent 5-9 parts by weight, steel fiber 80-90 parts by weight, modified graphene 0.03-0.08 parts by weight, expanding agent 3-5 parts by weight, viscosity regulator 1-3 parts by weight, and water 70-80 parts by weight; The preparation process of the modified graphene is as follows: graphene is added into a solvent, and then isopropyl tri(isostearyl) titanate and 2,2-bis[(4-trimethylsiloxy)phenyl]propane are added, and heating and stirring are performed to obtain the modified graphene; The mass ratio of the graphene, isopropyl tri(isostearyl) titanate and 2,2-bis[(4-trimethylsiloxy)phenyl]propane is 1:(3-5):(7-10), and the usage ratio of the graphene and the solvent is 1 g:80-100 mL; the solvent is N,N-dimethylformamide; The preparation process of the viscosity regulator is as follows: carboxymethyl cellulose, potassium hydroxide and urea are added into water, stirring is performed at room temperature, and then freezing is performed to obtain the viscosity regulator; the mass ratio of the potassium hydroxide, urea, water and carboxymethyl cellulose is 5:(8-12):(95-100):(3-5).

2. The ultra-high performance concrete material for a bridge structure according to claim 1, wherein The temperature of the heating and stirring is 80-100 DEG C, and the time is 2-5 h.

3. The ultra-high performance concrete material for bridge structures according to claim 1, characterized in that, The time of the stirring at room temperature is 40-60 min; the temperature of the freezing is-30--50 DEG C, and the time is 12-24 h.

4. The ultra-high performance concrete material for bridge structures according to claim 1, characterized by, The cement is high aluminate cement; the fine aggregate is quartz sand or river sand, the particle size is 0.08-2mm; the coarse aggregate is one or more of limestone, basalt stone or pebble, the particle size is 5-12mm; the water reducing agent is powder polycarboxylic acid high performance water reducing agent, the solid content is greater than 40%; the expansive agent is magnesium oxide or calcium sulphoaluminate expansive agent; the steel fiber is copper-plated steel fiber, the diameter is 0.1-0.3mm, the length is 10-15mm; the fly ash is low calcium fly ash, the particle size is 5-10µm, the density is 2-3g / cm 3 The mass content of SiO2 in the silica fume is greater than or equal to 95%.

5. The method according to any one of claims 1 to 4, wherein the method is characterized by, The method comprises the following steps: (1) each raw material component is weighed according to the weight parts, and is reserved; (2) cement, fly ash, silica ash, fine aggregate, coarse aggregate and expanding agent are mixed to obtain a first mixture; (3) water reducing agent, viscosity regulator and water are added into the first mixture and stirred, and then steel fiber and modified graphene are added and continuously stirred to obtain a second mixture; (4) the second mixture is poured into a mold, demolded after curing, and an ultra-high performance concrete is obtained.

6. Application of the ultra-high performance concrete material for bridge structure according to any one of claims 1-4 in the preparation of a bridge structure material.

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