Ultra-high performance concrete material for bridge structure as well as preparation method and application of ultra-high performance concrete material

Abstract

The invention discloses an ultra-high performance concrete material for a bridge structure as well as a preparation method and application thereof, and particularly relates to the field of concrete. The ultrahigh-performance concrete material for the bridge structure is prepared from the following raw materials in parts by weight: 230 to 240 parts of cement, 140 to 150 parts of fly ash, 50 to 60 parts of silica fume, 250 to 260 parts of fine aggregate, 50 to 60 parts of coarse aggregate, 5 to 9 parts of water reducing agent, 80 to 90 parts of steel fiber, 0.03 to 0.08 part of modified graphene, 3 to 5 parts of expanding agent, 1 to 3 parts of viscosity modifier and 70 to 80 parts of water. According to the prepared ultrahigh-performance concrete material for the bridge structure, the viscosity of the ultrahigh-performance concrete is improved, the compressive strength, the breaking strength, the tensile strength and other properties of the ultrahigh-performance concrete are improved, and the application prospect of the ultrahigh-performance concrete material in the concrete for the bridge is expanded.

Description

Technical Field

[0001] The present invention relates to the field of concrete, and particularly to an ultra-high performance concrete material for bridge structures, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous improvement of the requirements for material properties in modern bridge engineering, ultra-high performance concrete (UHPC), as a new type of cement-based composite material, has attracted much attention due to its excellent mechanical properties, high toughness, and ultra-long durability. Compared with ordinary concrete, UHPC significantly improves the deformation ability and mechanical strength of concrete by introducing components such as silica fume, fly ash, and steel fibers, and also expands its application in bridge structures, which can significantly enhance the bearing capacity of bridges, thereby extending the service life of bridges and reducing maintenance costs.

[0003] However, due to the very low water-binder ratio of ultra-high performance concrete, the viscosity of the concrete increases, which not only brings difficulties to the construction processes such as mixing, pouring, and vibrating of the concrete, reduces the construction efficiency, but also seriously affects the generation of internal stress during the hardening process of the concrete, increases the risk of concrete cracking, and affects its comprehensive performance. Aiming at the defects existing in the application of UHPC in bridge structures, traditional high-performance concrete mainly reduces the initial viscosity of UHPC by means of optimizing the raw material ratios such as cement and silica fume. Usually, the mechanical strength of the concrete is not considered, which limits its service time and quality in bridge service. Moreover, existing high-performance concrete mostly adopts a multiphase mixing system, and the density difference between components such as cement and aggregates will also lead to a decrease in the homogeneity and density of the concrete, ultimately resulting in poor mechanical properties of the concrete and affecting its application in bridges.

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

[0005] In order to overcome the deficiencies of the prior art, one of the purposes of the present invention is to provide an ultra-high performance concrete material for bridge structures, which can not only effectively improve the initial viscosity of the concrete, but also enhance its compressive strength, flexural strength, and tensile strength, improve the comprehensive performance of the material, and meet the requirements of bridge engineering for high-performance concrete materials.

[0006] Another purpose of the present invention is to provide a preparation method for an ultra-high performance concrete material for bridge structures, which is relatively simple, is conducive to improving construction efficiency, and is suitable for industrial production.

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

[0008] The first object of the present invention is achieved by the following technical solutions: An ultra-high performance concrete material for bridge structures, comprising the following raw materials in parts by weight: 230 - 240 parts of cement, 140 - 150 parts of fly ash, 50 - 60 parts of silica fume, 250 - 260 parts of fine aggregate, 50 - 60 parts of coarse aggregate, 5 - 9 parts of water reducing agent, 80 - 90 parts of steel fiber, 0.03 - 0.08 parts of modified graphene, 3 - 5 parts of expansive agent, 1 - 3 parts of viscosity regulator, and 70 - 80 parts of water.

[0009] Further, the preparation process of the modified graphene is as follows: Add graphene into a solvent, then add isopropyl tri(isostearoyl) titanate and 2,2 - bis[(4 - trimethylsiloxy)phenyl] propane, and heat and stir to obtain modified graphene.

[0010] Further, the mass ratio of the graphene, isopropyl tri(isostearoyl) titanate and 2,2 - bis[(4 - trimethylsiloxy)phenyl] propane is 1:(3 - 5):(7 - 10), and the dosage ratio of the graphene and the solvent is 1 g:80 - 100 mL; the solvent is N,N - dimethylformamide.

[0011] Further, the temperature of the heating and stirring is 80 - 100 °C, and the time is 2 - 5 h.

[0012] Among them, the present invention introduces modified graphene into ultra-high performance concrete, and the prepared modified graphene and cement gel matrix have good compatibility. Specifically, after the graphene is modified by a titanate coupling agent (isopropyl tri(isostearoyl) titanate), the surface of the graphene has more active groups, which improves the compatibility between the graphene and other substances. The introduced silicon-oxy-containing compound (2,2 - bis[(4 - trimethylsiloxy)phenyl] propane) can further modify the surface of the graphene, change the surface energy of the graphene, and reduce the generation of agglomeration. In addition, the isopropyl tri(isostearoyl) titanate and 2,2 - bis[(4 - trimethylsiloxy)phenyl] propane are intertwined in long chains, and a cross-linked structure is formed between the two and the graphene, which can improve the compactness of the concrete material, interact with components such as cement to form a densified structure, and the entire concrete system is closely packed, improving the compressive strength, stability and other properties of the concrete material.

[0013] Further, the preparation process of the viscosity regulator is as follows: Add carboxymethyl cellulose, potassium hydroxide and urea into water, stir at room temperature, and then freeze to obtain the viscosity regulator.

[0014] Furthermore, the mass ratio of potassium hydroxide, urea, water, and carboxymethyl cellulose is 5:(8 - 12):(95 - 100):(3 - 5).

[0015] Furthermore, the stirring time is 40 - 60 min; the freezing temperature is -30 to -50 °C, and the time is 12 - 24 h.

[0016] Among them, in the present invention, a viscosity regulator is introduced, that is, carboxymethyl cellulose interacts with potassium hydroxide and urea to prepare a viscosity regulator. The addition of potassium hydroxide and urea helps to break the hydrogen bonds between cellulose molecules. At the same time, this viscosity regulator can reduce the cohesion of the concrete system by destroying the flocculation structure between cement particles, thereby regulating the fluidity of the concrete slurry, improving the viscosity of the concrete, making each component in the concrete easier to be stirred and mixed evenly, reducing the defect of agglomeration in the concrete material, and enabling the concrete material to maintain high mechanical properties.

[0017] Furthermore, the fine aggregate is quartz sand or river sand, with a particle size of 0.08 - 2 mm; the coarse aggregate is one or more of limestone, basalt, or cobblestone, with a particle size of 5 - 12 mm; the water reducer is a powder polycarboxylate superplasticizer with a solid content greater than 40%; the expansive agent is a magnesia-based or calcium sulfoaluminate-based expansive agent; the steel fiber is a copper-plated steel fiber with a diameter of 0.1 - 0.3 mm and a length of 10 - 15 mm; the fly ash is low-calcium fly ash with a particle size of 5 - 10 µm and a density of 2 - 3 g / cm 3 , and the mass content of SiO2 ≥ 40%; the silica fume is fully densified silica fume, and the mass content of SiO2 in the silica fume ≥ 95%.

[0018] The second object of the present invention is achieved by the following technical solution: The preparation method of the above ultra-high performance concrete material for bridge structures includes the following steps: (1) Weigh each raw material component according to the said weight parts and set aside; (2) Mix cement, fly ash, silica fume, fine aggregate, coarse aggregate, and expansive agent to obtain a first mixture; (3) Add a water reducer, a viscosity regulator, and water to the first mixture and stir, then add steel fiber and modified graphene and continue to stir to obtain a second mixture; (4) Pour the second mixture into a mold, cure it, and then demold it to obtain ultra-high performance concrete.

[0019] Furthermore, the curing temperature is 18 - 22 °C, and the humidity is above 94%.

[0020] The third object of the present invention is achieved by the following technical solution: Application of the ultra-high performance concrete material for bridge structures in the preparation of bridge structure materials.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention provides an ultra-high performance concrete material for bridge structures. Based on the cementitious system of cement, fly ash, and silica fume, modified graphene and a viscosity regulator are introduced, enabling uniform distribution of each component. The concrete system is overall homogeneous and dense, which can improve the viscosity of the ultra-high performance concrete while enhancing its compressive strength, flexural strength, tensile strength and other properties, effectively ensuring the application of the concrete in bridge structure reinforcement and extending its service life in bridge service.

[0022] 2. The present invention also provides a preparation method for the ultra-high performance concrete material for bridge structures. This method has a relatively simple process, convenient construction, and is suitable for industrial production and popularization. Detailed implementation manners

[0023] Next, in combination with the specific implementation manners, the present invention will be further described. It should be noted that, on the premise of no conflict, any combination of the following-described embodiments or technical features can form a new embodiment. Specific conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are conventional products obtained through commercial channels.

[0024] The fine aggregate of the present invention is quartz sand or river sand, with a particle size of 0.08 - 2 mm; The coarse aggregate is one or more of limestone, basalt or pebbles, with a particle size of 5 - 12 mm; The water reducing agent is a powder polycarboxylate superplasticizer, with a solid content greater than 40%; The expansion agent is a magnesia-based or calcium sulfoaluminate-based expansion agent; The steel fiber is a copper-plated steel fiber, with a diameter of 0.1 - 0.3 mm and a length of 10 - 15 mm.

[0025] The cement is high aluminate cement; The fly ash is low-calcium fly ash, with a particle size of 5 - 10 µm and a density of 2 - 3 g / cm 3 , and the mass content of SiO2 ≥ 40%; The silica fume is fully densified silica fume, and the mass content of SiO2 in the silica fume ≥ 95%.

[0026] Example 1 This embodiment provides a ultra-high performance concrete material for bridge structures, comprising the following raw materials in parts by weight: 235 parts of cement, 145 parts of fly ash, 55 parts of silica fume, 255 parts of fine aggregate (quartz sand), 55 parts of coarse aggregate (limestone), 7 parts of water reducing agent, 85 parts of steel fiber, 0.05 part of modified graphene, 4 parts of expansive agent (magnesium oxide-based expansive agent), 2 parts of viscosity regulator, and 75 parts of water.

[0027] Among them, the preparation process of the modified graphene is as follows: Weigh graphene, isopropyltri(isostearoyl) titanate, and 2,2-bis[(4-trimethylsiloxysilyl)phenyl] propane according to a mass ratio of 1:4:9 respectively, and set aside; First, add graphene to N,N-dimethylformamide for ultrasonic dispersion, then add isopropyltri(isostearoyl) titanate and 2,2-bis[(4-trimethylsiloxysilyl)phenyl] propane, stir at 90 °C for 3 h, filter the reaction solution, wash and dry the filter residue to obtain modified graphene.

[0028] The preparation process of the viscosity regulator is as follows: Add carboxymethyl cellulose, potassium hydroxide, and urea to deionized water, where the mass ratio of potassium hydroxide, urea, deionized water, and carboxymethyl cellulose is 5:8:100:5; Stir at room temperature for 50 min, and freeze at -40 °C for 18 h to obtain the viscosity regulator.

[0029] This embodiment also provides a preparation method for the above ultra-high performance concrete material for bridge structures, comprising the following steps: (1) Weigh each raw material component according to the above parts by weight and set aside; (2) Mix cement, fly ash, silica fume, fine aggregate, coarse aggregate, and expansive agent to obtain a first mixture; (3) Add a water reducing agent, viscosity regulator, and water to the first mixture and stir, then add steel fiber and modified graphene and continue to stir to obtain a second mixture; (4) Pour the second mixture into a mold, cure it in a curing room for 28 d and then demold it. The temperature of the curing room is 20 °C and the humidity is above 94% to obtain ultra-high performance concrete.

[0030] Example 2 This embodiment provides a ultra-high performance concrete material for bridge structures, comprising the following raw materials in parts by weight: 230 parts of cement, 140 parts of fly ash, 50 parts of silica fume, 250 parts of fine aggregate (river sand), 50 parts of coarse aggregate (basalt), 5 parts of water reducing agent, 80 parts of steel fiber, 0.03 part of modified graphene, 3 parts of expansive agent (calcium sulfoaluminate-based expansive agent), 1 part of viscosity regulator, and 70 parts of water.

[0031] Among them, the preparation process of the modified graphene is as follows: Weigh graphene, isopropyltris(isostearoyl)titanate, and 2,2-bis[(4-trimethylsiloxysilyl)phenyl]propane according to a mass ratio of 1:3:7 respectively, and set aside. First, add the graphene to N,N-dimethylformamide for ultrasonic dispersion, then add isopropyltris(isostearoyl)titanate and 2,2-bis[(4-trimethylsiloxysilyl)phenyl]propane, and stir at 80 °C for 5 h. Filter the reaction solution, wash and dry the filter residue to obtain the modified graphene.

[0032] The preparation process of the viscosity regulator is as follows: Add carboxymethyl cellulose, potassium hydroxide, and urea to deionized water, where the mass ratio of potassium hydroxide, urea, deionized water, and carboxymethyl cellulose is 5:8:100:3. Stir at room temperature for 40 min, and then freeze at -30 °C for 24 h to obtain the viscosity regulator.

[0033] This embodiment also provides a preparation method for the ultra-high performance concrete material for the bridge structure, including the following steps: (1) Weigh each raw material component according to the above weight parts and set aside; (2) Mix cement, fly ash, silica fume, fine aggregate, coarse aggregate, and expansion agent to obtain a first mixture; (3) Add a water reducer, viscosity regulator, and water to the first mixture and stir, then add steel fibers and modified graphene and continue to stir to obtain a second mixture; (4) Pour the second mixture into a mold and cure it in a curing room for 28 d and then demold it. The temperature of the curing room is 18 °C and the humidity is above 94% to obtain ultra-high performance concrete.

[0034] Example 3 This embodiment provides an ultra-high performance concrete material for a bridge structure, including the following raw materials in weight parts: 240 parts of cement, 150 parts of fly ash, 60 parts of silica fume, 260 parts of fine aggregate (quartz sand), 60 parts of coarse aggregate (pebble), 9 parts of water reducer, 90 parts of steel fiber, 0.08 part of modified graphene, 5 parts of expansion agent (magnesium oxide-based expansion agent), 3 parts of viscosity regulator, and 80 parts of water.

[0035] Among them, the preparation process of the modified graphene is as follows: Weigh graphene, isopropyltris(isostearoyl)titanate, and 2,2-bis[(4-trimethylsiloxysilyl)phenyl]propane according to a mass ratio of 1:5:10 respectively, and set aside. First, add the graphene to N,N-dimethylformamide for ultrasonic dispersion, then add isopropyltris(isostearoyl)titanate and 2,2-bis[(4-trimethylsiloxysilyl)phenyl]propane, and stir at 100 °C for 2 h. Filter the reaction solution, wash and dry the filter residue to obtain the modified graphene.

[0036] The preparation process of the viscosity regulator is as follows: carboxymethyl cellulose, potassium hydroxide, and urea are added to deionized water, and the mass ratio of potassium hydroxide, urea, deionized water, and carboxymethyl cellulose is 5:8:100:4; stir at room temperature for 60 min, and freeze at -50 °C for 15 h to obtain the viscosity regulator.

[0037] This embodiment also provides a preparation method for the above ultra-high performance concrete material for bridge structures, including the following steps: (1) Weigh each raw material component according to the above parts by weight and set aside; (2) Mix cement, fly ash, silica fume, fine aggregate, coarse aggregate, and expansive agent to obtain a first mixture; (3) Add a water reducer, viscosity regulator, and water to the first mixture and stir, then add steel fibers and modified graphene and continue to stir to obtain a second mixture; (4) Pour the second mixture into a mold, place it in a curing room for 28 d and then demold it. The temperature of the curing room is 22 °C and the humidity is above 94% to obtain ultra-high performance concrete.

[0038] Comparative Example 1 This Comparative Example 1 is basically the same as Example 1, except that: graphene is used instead of modified graphene, and the others are the same as Example 1.

[0039] Comparative Example 2 This Comparative Example 2 is basically the same as Example 1, except that: isopropyltri(isostearoyl) titanate is omitted in the process of preparing modified graphene, and the others are the same as Example 1.

[0040] Comparative Example 3 This Comparative Example 3 is basically the same as Example 1, except that: 2,2-bis[(4-trimethylsiloxyphenyl)propane] is omitted in the process of preparing modified graphene, and the others are the same as Example 1.

[0041] Comparative Example 4 This Comparative Example 4 is basically the same as Example 1, except that: the viscosity regulator is replaced by carboxymethyl cellulose, and the others are the same as Example 1.

[0042] Test Example 1 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 viscosities of the samples obtained in Examples 1-3 and Comparative Examples 1-4 were tested using a rheometer, and the test results are shown in Table 1.

[0043] Table 1 Performance test results It can be seen from the test results in Table 1 that 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 composition of the concrete is optimized in the present invention. The introduced modified graphene and cement gel matrix have good compatibility, which can improve the compactness of the concrete material, interact with cement, etc. to form a densified structure. The entire concrete system is closely packed, improving the performance of the concrete material such as compressive strength and stability. The viscosity regulator can adjust the fluidity of the concrete slurry, thereby effectively reducing the viscosity of the concrete, making each component in the concrete easier to stir and mix evenly, and maintaining the uniformity and compactness of the concrete. The generation and expansion of cracks caused by viscosity problems in the concrete are eliminated, thereby improving the overall performance of the bridge. The above results show that the introduction of modified graphene and viscosity regulator in this application not only improves the viscosity of the ultra-high performance concrete, but also simultaneously improves its performance such as compressive strength, flexural strength, and tensile strength, expanding its application prospects in bridge concrete.

[0044] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantive changes and substitutions made by those skilled in the art based on the present invention belong to the scope of protection required by the present invention.

Claims

1. An ultra-high performance concrete material for a bridge structure, characterized in that: The invention comprises the following raw materials in parts by weight: 230-240 parts of cement, 140-150 parts of fly ash, 50-60 parts of silica fume, 250-260 parts of fine aggregate, 50-60 parts of coarse aggregate, 5-9 parts of water reducer, 80-90 parts of steel fiber, 0.03-0.08 parts of modified graphene, 3-5 parts of expansion agent, 1-3 parts of viscosity regulator and 70-80 parts of water.

2. The ultra-high performance concrete material for bridge structure according to claim 1, characterized in that: The preparation process of the modified graphene is as follows: adding graphene into a solvent, then adding isopropyl tri(isostearoyl) titanate and 2,2-bis[(4-trimethylsilyloxy)phenyl]propane, heating and stirring to obtain the modified graphene.

3. The ultra-high performance concrete material for bridge structure according to claim 2, characterized in that: The mass ratio of the graphene, isopropyl tri(isostearoyl) titanate and 2,2-bis[(4-trimethylsilyloxy)phenyl]propane is 1:(3-5):(7-10), the amount ratio of the graphene and the solvent is 1 g:80-100 mL; and the solvent is N,N-dimethylformamide.

4. The ultra-high performance concrete material for bridge structure according to claim 2, characterized in that: The heating and stirring is performed at a temperature of 80-100° C. and for a time of 2-5 hours.

5. The ultra-high performance concrete material for bridge structure according to claim 1, characterized in that: The preparation process of the viscosity regulator is as follows: carboxymethyl cellulose, potassium hydroxide and urea are added into water, stirred at room temperature, and then frozen to obtain the viscosity regulator.

6. The ultra-high performance concrete material for bridge structure according to claim 5, characterized in that: The mass ratio of potassium hydroxide, urea, water and carboxymethyl cellulose is 5:(8-12):(95-100):(3-5).

7. The ultra-high performance concrete material for bridge structure according to claim 5, characterized in that: The stirring time is 40 to 60 minutes; the freezing temperature is -30 to -50°C, and the time is 12 to 24 hours.

8. The ultra-high performance concrete material for bridge structure according to claim 1, characterized in that: The fine aggregate is quartz sand or river sand with a particle size of 0.08-2 mm; the coarse aggregate is one or more of limestone, basalt or pebbles with a particle size of 5-12 mm; the water reducer is a powdered polycarboxylic acid high-performance water reducer with a solid content greater than 40%; the expansion agent is a magnesium oxide or calcium sulfoaluminate expansion agent; the steel fiber is a copper-plated steel fiber with a diameter of 0.1-0.3 mm and a length of 10-15 mm; the fly ash is low-calcium fly ash with a particle size of 5-10 µm and a density of 2-3 g / cm 3 , the mass content of SiO2 is ≥40%; the silica ash is fully encrypted silica ash, and the mass content of SiO2 in the silica ash is ≥95%.

9. The method for preparing an ultra-high performance concrete material for a bridge structure according to any one of claims 1 to 8, characterized in that: The steps include: (1) Weighing each raw material component according to the stated weight proportions and setting aside; (2) mixing cement, fly ash, silica fume, fine aggregate, coarse aggregate and expansion agent to obtain a first mixture; (3) adding a water reducing agent, a viscosity modifier and water to the first mixture and stirring, and then adding steel fiber and modified graphene and continuing to stir to obtain a second mixture; (4) The second mixture is poured into a mold and demolded after curing to obtain ultra-high performance concrete.

10. Use of the ultra-high performance concrete material for bridge structure as claimed in any one of claims 1 to 8 in the preparation of bridge structure materials.

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