High-strength conductive concrete and preparation method thereof

Abstract

The invention discloses high-strength conductive concrete, which is prepared from the following components in parts by weight: 380 to 400 parts of Portland cement, 200 to 220 parts of water, 800 to 820 parts of river sand, 880 to 900 parts of gravel, 135 to 140 parts of fly ash, 5 to 10 parts of polycarboxylate superplasticizer, 40 to 50 parts of surface modified steel fiber and 5 to 15 parts of modified nano titanium dioxide particles, wherein the surface modified steel fibers are nano-zinc oxide coated steel fibers, and the modified nano-titanium dioxide particles are nano-titanium dioxide particles of which the surfaces are coated with Ce-doped zinc oxide conductive layers. The doped surface-modified steel fibers comprise long fibers and short fibers, and the shapes of the doped surface-modified steel fibers comprise straight, end-hook-shaped and wave-shaped. The surface modified steel fibers and the modified nano titanium dioxide particles are compositely doped in the concrete, so that the resistivity is reduced, the tensile strength, the compressive strength and the bending strength of the concrete are improved, and the high-strength conductive concrete is obtained.

Description

Technical Field

[0001] The present invention relates to the field of building materials, and particularly to a high-strength conductive concrete. Background Art

[0002] Concrete is a hydraulic cementitious material, mainly composed of cement, fine and coarse aggregates, admixtures and water mixed and stirred in a certain proportion. It belongs to artificial composite stone. Its advantages lie in strong plasticity, good durability and convenient production, and it is widely used in construction, bridges, roads, national defense projects and other aspects. The resistivity of ordinary concrete is usually between 10 6 ~10 9 Ω·cm, belonging to a poor conductor of electricity. By doping appropriate amounts of various conductive materials such as carbon-based materials, metals and metal oxides, and polymers in concrete, conductive concrete can be prepared, and its resistivity is in the range of 10 -1 ~10 4 Ω·cm. Conductive concrete has both the excellent properties of structural materials and characteristics such as conductivity, piezoresistivity, and thermosensitivity. It is usually applied to electromagnetic shielding, melting ice and snow, indoor heating, industrial anti-static, etc. In addition, it can also be used to monitor the structural changes of concrete by equipment. The admixtures of conductive concrete are usually divided into two categories: one is fibrous admixtures, such as steel fibers, carbon fibers, etc.; the other is granular admixtures, such as nano carbon black, metal powders, etc. Different admixtures have different effects on reducing the resistivity of concrete and also have different effects on mechanical properties. In order to balance a low resistivity and good comprehensive mechanical properties, different forms and materials of conductive materials are usually compounded and doped in concrete in order to produce a positive hybrid effect. The resistivity of steel fibers is about (1.33~2.44)×10 -5 Ω·cm. Doping steel fibers can effectively reduce the resistivity of concrete. At the same time, steel fibers can be used as a reinforcing phase to improve the compressive strength, tensile strength and durability of concrete. However, the surface of steel fibers is smooth, the interfacial bonding with concrete is relatively weak, and it is easy to rust in concrete, resulting in the difficulty of fully exerting the strengthening and toughening effect of steel fibers on concrete. Preparing a conductive coating on the surface of steel fibers can enhance the interfacial bonding force between the fibers and concrete, improve the mechanical properties, and at the same time improve the corrosion resistance of steel fibers without affecting their conductivity. Nano-titanium dioxide is a typical active nano material. As a filling material, it can optimize the pore distribution of concrete, make the microstructure of concrete more dense, improve its mechanical properties, and have a certain self-cleaning property. In addition, nano-titanium dioxide particles have conductivity and photocatalytic properties, and the resistivity can reach 10~100Ω·cm after surface modification. Adding it to concrete can also play a role in reducing resistance. Summary of the Invention

[0003] Technical problem to be solved: The technical problem to be solved by the present invention is to provide a high-strength conductive concrete.

[0004] Technical solution: A high-strength conductive concrete, comprising the following components in parts by weight: Portland cement: 380 - 400 parts; Water: 200 - 220 parts; River sand: 800 - 820 parts; Crushed stone: 880 - 900 parts; Fly ash: 135 - 140 parts; Polycarboxylate water reducer: 5 - 10 parts; Surface-modified steel fibers: 40 - 50 parts; Modified nano-titanium dioxide particles: 5 - 15 parts. Preferably, the surface-modified steel fibers are steel fibers coated with nano-zinc oxide. Preferably, the preparation method of the nano-zinc oxide-coated steel fibers is electrophoretic deposition, comprising the following steps: S11. Clean the steel fibers. First, rinse off the grease and other impurities on the surface of the steel fibers with absolute ethanol, and then rinse with deionized water until the pH value is neutral, and dry at room temperature; S12. Prepare a suspension. Add nano-zinc oxide to deionized water with a concentration of 0.05 - 0.1 wt%, and ultrasonically disperse for 10 - 20 min; S13. Electrophoretic deposition. Place the steel fibers as the cathode material into the suspension, apply a direct current of 3 - 7 V, and process for 5 - 15 min; S14. Clean and dry. Take out the treated steel fibers, rinse them clean with deionized water, put them into an oven for drying, the drying temperature is 60 - 70 °C, and the drying time is 20 - 25 h. Preferably, the morphology of the surface-modified steel fibers includes straight, end-hooked, and wavy shapes. Preferably, the surface-modified steel fibers include long fibers and short fibers. The length range of the long fibers is 20 - 40 mm, the equivalent diameter range is 0.3 - 0.6 mm, and the aspect ratio is between 50 - 80; the length range of the short fibers is 5 - 10 mm, the equivalent diameter range is 0.2 - 0.4 mm, and the aspect ratio is between 10 - 25. Preferably, the modified nano-titanium dioxide particles are nano-titanium dioxide particles with a conductive layer of zinc oxide doped with Ce on the surface. Preferably, the preparation method of the nano-titanium dioxide particles with a conductive layer of zinc oxide doped with Ce on the surface is chemical co-precipitation, comprising the following steps: S21. Add zinc chloride and cerium chloride to a hydrochloric acid solution, stir well to dissolve, and obtain a mixed solution; S22. Add deionized water to titanium dioxide particles, and ultrasonically stir for 5 - 15 min to make titanium dioxide and deionized water miscible, obtaining a titanium dioxide suspension; S23. Drop the mixed solution of S21 into the titanium dioxide suspension, and simultaneously dropwise add sodium hydroxide solution, and keep stirring to promote the reaction. After the addition is completed, keep the reaction at a certain temperature for 1 - 1.5 h; S24. Filter, wash, dry, grind and calcine the obtained reactants to obtain nano - titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface. Preferably, the particle size range of the modified nano - titanium dioxide particles is 10 - 100 nm. Preferably, the particle size of the river sand is 1 - 5 mm, and the particle size of the crushed stone is 5 - 20 mm. Preferably, the preparation method of the high - strength conductive concrete includes the following steps: S1. Add water to the modified nano - titanium dioxide particles, and ultrasonically stir for 10 - 15 min to obtain a uniformly dispersed suspension; S2. Weigh the corresponding weights of fly ash, river sand and steel fibers, pour them into a mixer and dry - mix for 1 - 3 min to obtain a uniform primary mixture; S3. Add the corresponding weights of river sand and cement to the primary mixture, and dry - mix for 3 - 5 min to obtain a secondary mixture; S4. Add the corresponding weights of the suspension, water - reducing agent and water to the secondary mixture, and wet - mix for 5 - 10 min to obtain concrete. Beneficial effects: Compared with the prior art, the present invention has the following characteristics: For the conductive concrete of the present invention, surface - modified steel fibers and surface - modified nano - titanium dioxide particles are compound - doped as conductive materials, which can effectively reduce the resistivity of the concrete. At the same time, the doping of steel fibers can improve the tensile strength and flexural strength of the concrete, and the doping of nano - titanium dioxide particles can improve the compressive strength and frost resistance of the concrete. The compound doping of the two can effectively improve the comprehensive performance of the concrete. Steel fibers themselves possess high strength, high elasticity, and good electrical conductivity. Incorporating steel fibers into concrete can not only reduce the resistivity but also be an effective way to improve the performance of concrete. Moreover, steel fibers have excellent dispersibility and are not prone to agglomeration during the preparation process, which can simplify the production process and reduce production costs. Steel fibers with different morphologies and lengths have different bonding strengths and angles with the matrix, resulting in different strengthening effects on concrete. Therefore, doping steel fibers with different morphologies and lengths can achieve better comprehensive strengthening effects. However, the surface of steel fibers is smooth, which easily forms a weak bonding layer with the concrete matrix, leading to low interfacial bonding strength and affecting the mechanical properties of the matrix. Modifying the surface of steel fibers by coating a conductive nano-zinc oxide layer can increase the surface roughness of steel fibers, improve the interfacial bonding strength, and at the same time, does not affect the overall electrical conductivity of the concrete. In addition, as a corrosion inhibitor, nano-zinc oxide coated on the surface of steel fibers can effectively prevent them from rusting or passivating, ensuring the durability and electrical conductivity of the concrete. As a modified material for concrete, nano-titanium dioxide has small-size effect and filling effect, which can improve the microstructure of concrete, thereby enhancing the macroscopic properties. And nano-titanium dioxide has certain self-cleaning and photocatalytic properties, and adding it to concrete is environmentally friendly. However, as a metal oxide, nano-titanium dioxide has poor electrical conductivity. Therefore, through surface modification, coating a zinc oxide layer doped with Ce on its surface can reduce its resistivity to 10 - 100 Ω·cm while improving the mechanical properties of the nanoparticles. Adding surface-modified nano-titanium dioxide particles to concrete can not only reduce the resistivity but also endow the concrete with excellent comprehensive mechanical properties. Compared with the prior art, the present invention has the following advantages and positive effects: The present invention compositely dopes surface-modified steel fibers and surface-modified nano-titanium dioxide particles in concrete, which can improve the mechanical properties of concrete while reducing the resistivity of the concrete. The surface modification methods of the fibers and nano-particles used in the present invention have simple steps, convenient operation, controllable processes, and the coatings can effectively improve the comprehensive properties of concrete. The concrete preparation process used in the present invention is simple, and the fibers and nano-particles have good dispersibility, effectively avoiding the occurrence of agglomeration, sedimentation, etc. Detailed Embodiments To further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with examples. The specific preferred examples are as follows: Example 1: A high-strength conductive concrete, comprising the following components in weight ratio: Portland cement: 380 parts; Water: 220 parts; River sand: 800 parts; Crushed stone: 900 parts; Fly ash: 135 parts; Polycarboxylate superplasticizer: 10 parts; Surface-modified steel fiber: 40 parts; Modified nano-titanium dioxide particles: 15 parts; The surface-modified steel fiber is a steel fiber coated with nano-zinc oxide; The preparation method of the nano-zinc oxide-coated steel fiber is electrophoretic deposition, including the following steps: S11. Clean the steel fiber. First, use anhydrous ethanol to rinse off impurities such as grease on the surface of the steel fiber, and then use deionized water to rinse until the pH value is neutral, and dry at room temperature; S12. Prepare a suspension. Add nano-zinc oxide to deionized water with a concentration of 0.05wt%, and use ultrasonic dispersion for 10 min; S13. Electrophoretic deposition. Place the steel fiber as the cathode material into the suspension, pass a direct current of 3V, and process for 15 min; S14. Clean and dry. Take out the treated steel fiber, rinse it with deionized water, put it into an oven for drying, the drying temperature is 70°C, and the drying time is 20 h; The morphology of the surface-modified steel fiber includes straight, end-hooked, and wavy shapes; The surface-modified steel fiber includes long fibers and short fibers. The length range of the long fibers is 20 - 40 mm, the equivalent diameter range is 0.3 - 0.6 mm, and the aspect ratio is between 50 - 80; the length range of the short fibers is 5 - 10 mm, the equivalent diameter range is 0.2 - 0.4 mm, and the aspect ratio is between 10 - 25; The modified nano-titanium dioxide particles are nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The preparation method of the nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface is chemical co-precipitation, including the following steps: S21. Add zinc chloride and cerium chloride to the hydrochloric acid solution, stir and dissolve thoroughly to obtain a mixed solution; S22. Add deionized water to the titanium dioxide particles, stir ultrasonically for 15 min to make the titanium dioxide and deionized water miscible, and obtain a titanium dioxide suspension; S23. Drop the mixed solution of S21 into the titanium dioxide suspension, and at the same time drop the sodium hydroxide solution, and keep stirring to promote the reaction. After dropping, keep the reaction at a constant temperature for 1.5 h; S24. Filter, wash, dry, grind, and calcine the obtained reactants to obtain nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The particle size range of the modified nano-titanium dioxide particles is 10 - 100 nm; The particle size of the river sand is 1 - 5 mm, and the particle size of the crushed stone is 5 - 20 mm; The preparation method of the high-strength conductive concrete includes the following steps: S1. Add water to the modified nano-titanium dioxide particles and ultrasonically stir for 15 min to obtain a uniformly dispersed suspension; S2. Weigh the corresponding weights of fly ash, river sand, and steel fibers, pour them into a mixer and dry mix for 1 min to obtain a uniform primary mixture; S3. Add the corresponding weights of river sand and cement to the primary mixture and dry mix for 3 min to obtain a secondary mixture; S4. Add the corresponding weights of the suspension, water reducing agent, and water to the secondary mixture and wet mix for 10 min to obtain the concrete. Example 2: A high-strength conductive concrete, comprising the following components by weight ratio: Portland cement: 400 parts; Water: 200 parts; River sand: 820 parts; Crushed stone: 880 parts; Fly ash: 140 parts; Polycarboxylate water reducing agent: 5 parts; Surface-modified steel fibers: 50 parts; Modified nano-titanium dioxide particles: 5 parts; The surface-modified steel fibers are steel fibers coated with nano-zinc oxide; The preparation method of the nano-zinc oxide-coated steel fibers is electrophoretic deposition, including the following steps: S11. Clean the steel fibers. First, use anhydrous ethanol to rinse off impurities such as grease on the surface of the steel fibers, then use deionized water to rinse until the pH value is neutral, and dry at room temperature; S12. Prepare a suspension. Add nano-zinc oxide to deionized water with a concentration of 0.1 wt%, and ultrasonically disperse for 20 min; S13. Electrophoretic deposition. Place the steel fibers as the cathode material into the suspension, pass a direct current of 7 V, and process for 5 min; S14. Wash and dry. Take out the treated steel fibers, rinse them with deionized water, put them into an oven to dry, the drying temperature is 60 °C, and the drying time is 25 h; The morphology of the surface-modified steel fibers includes straight, end-hooked, and wavy shapes; The surface-modified steel fibers include long fibers and short fibers. The length range of the long fibers is 20 - 40 mm, the equivalent diameter range is 0.3 - 0.6 mm, and the aspect ratio is between 50 - 80; the length range of the short fibers is 5 - 10 mm, the equivalent diameter range is 0.2 - 0.4 mm, and the aspect ratio is between 10 - 25; The modified nano titanium dioxide particles are nano titanium dioxide particles with a surface coated with a Ce-doped zinc oxide conductive layer; The preparation method of the nano titanium dioxide particles with a surface-coated Ce-doped zinc oxide conductive layer is a chemical coprecipitation method, comprising the following steps: S21. Add zinc chloride and cerium chloride to the hydrochloric acid solution, stir and dissolve to obtain a mixed solution; S22. Deionized water was added to the titanium dioxide particles and ultrasonically stirred for 5 min to dissolve the titanium dioxide and deionized water to obtain a titanium dioxide suspension; S23. The mixed solution of S21 was dropped into the titanium dioxide suspension, and sodium hydroxide solution was added dropwise, and stirring was maintained to promote the reaction. After the addition was completed, the reaction was kept warm for 1h; S24. The resulting reactant is filtered, washed, dried, ground and calcined to obtain nano-titanium dioxide particles having a surface-coated Ce-doped zinc oxide conductive layer; The particle size of the modified nano titanium dioxide particles ranges from 10 to 100 nm; The particle size of the river sand is 1 to 5 mm, and the particle size of the crushed stone is 5 to 20 mm; The preparation method of the high-strength conductive concrete comprises the following steps: S1. Add water to the modified nano-titanium dioxide particles and stir ultrasonically for 10 min to obtain a uniformly dispersed suspension; S2. Weigh the corresponding weight of fly ash, river sand and steel fiber, pour into the mixer and dry mix for 3 minutes to obtain a uniform primary mixture; S3. Add the corresponding weight of river sand and cement to the primary mixture, dry mix for 5 minutes to obtain a secondary mixture; S4. Add corresponding weights of suspension, water reducing agent and water to the secondary mixture and wet mix for 5 minutes to obtain concrete. Embodiment 3: A high-strength conductive concrete comprising the following components in weight ratio: Portland cement: 385 parts; Water: 215 parts; River sand: 810 parts; Crushed stone: 890 pieces; Fly ash: 138 parts; Polycarboxylate water reducer: 7 parts; Surface modified steel fiber: 46 parts; Modified nano titanium dioxide particles: 9 parts; The surface modified steel fiber is a nano zinc oxide coated steel fiber; The preparation method of the nano zinc oxide coated steel fiber is an electrophoretic deposition method, comprising the following steps: S11. Clean the steel fibers. First, rinse off impurities such as grease on the surface of the steel fibers with anhydrous ethanol, and then rinse with deionized water until the pH value is neutral, and dry at room temperature; S12. Prepare a suspension. Add nano-zinc oxide to deionized water at a concentration of 0.08 wt%, and disperse it ultrasonically for 17 min; S13. Electrophoretic deposition. Place the steel fibers as the cathode material into the suspension, and pass a direct current of 5 V for 12 min; S14. Clean and dry. Take out the treated steel fibers, rinse them clean with deionized water, put them into an oven to dry, the drying temperature is 64 °C, and the drying time is 23 h; The morphology of the surface-modified steel fibers includes straight shape, end-hook shape and wavy shape; The surface-modified steel fibers include long fibers and short fibers. The length range of the long fibers is 20 - 40 mm, the equivalent diameter range is 0.3 - 0.6 mm, and the aspect ratio is between 50 - 80; the length range of the short fibers is 5 - 10 mm, the equivalent diameter range is 0.2 - 0.4 mm, and the aspect ratio is between 10 - 25; The modified nano-titanium dioxide particles are nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The preparation method of the nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface is the chemical co-precipitation method, including the following steps: S21. Add zinc chloride and cerium chloride to the hydrochloric acid solution, stir well to dissolve, and obtain a mixed solution; S22. Add deionized water to the titanium dioxide particles, stir ultrasonically for 10 min to make the titanium dioxide and deionized water miscible, and obtain a titanium dioxide suspension; S23. Drop the mixed solution of S21 into the titanium dioxide suspension, and at the same time drop the sodium hydroxide solution, and keep stirring to promote the reaction. After dropping, keep the reaction at a constant temperature for 1.3 h; S24. Filter, wash, dry, grind and calcine the obtained reactants to obtain nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The particle size range of the modified nano-titanium dioxide particles is 10 - 100 nm; The particle size of the river sand is 1 - 5 mm, and the particle size of the crushed stone is 5 - 20 mm; The preparation method of the high-strength conductive concrete includes the following steps: S1. Add water to the modified nano-titanium dioxide particles, stir ultrasonically for 12 min to obtain a uniformly dispersed suspension; S2. Weigh the corresponding weights of fly ash, river sand, and steel fibers, pour them into a mixer and dry mix for 2 min to obtain a uniform primary mixture; S3. Add the corresponding weights of river sand and cement to the primary mixture and dry mix for 4 min to obtain a secondary mixture; S4. Add the corresponding weights of suspension, water reducing agent, and water to the secondary mixture and wet mix for 7 min to obtain concrete. Example 4: A high-strength conductive concrete, comprising the following components by weight ratio: Portland cement: 390 parts; Water: 210 parts; River sand: 805 parts; Crushed stone: 895 parts; Fly ash: 136 parts; Polycarboxylate water reducing agent: 9 parts; Surface-modified steel fibers: 43 parts; Modified nano-titanium dioxide particles: 12 parts; The surface-modified steel fibers are steel fibers coated with nano-zinc oxide; The preparation method of the nano-zinc oxide-coated steel fibers is electrophoretic deposition, including the following steps: S11. Clean the steel fibers. First, use anhydrous ethanol to rinse off impurities such as grease on the surface of the steel fibers, then use deionized water to rinse until the pH value is neutral, and dry at room temperature; S12. Prepare a suspension. Add nano-zinc oxide to deionized water with a concentration of 0.06 wt%, and use ultrasonic dispersion for 12 min; S13. Electrophoretic deposition. Place the steel fibers as the cathode material into the suspension, pass a direct current of 4 V, and process for 10 min; S14. Clean and dry. Take out the treated steel fibers, rinse them with deionized water, put them into an oven to dry, the drying temperature is 67 °C, and the drying time is 21 h; The morphology of the surface-modified steel fibers includes straight, end-hooked, and wavy shapes; The surface-modified steel fibers include long fibers and short fibers. The length range of the long fibers is 20 - 40 mm, the equivalent diameter range is 0.3 - 0.6 mm, and the aspect ratio is between 50 - 80; the length range of the short fibers is 5 - 10 mm, the equivalent diameter range is 0.2 - 0.4 mm, and the aspect ratio is between 10 - 25; The modified nano-titanium dioxide particles are nano-titanium dioxide particles with a surface-coated zinc oxide conductive layer doped with Ce; The preparation method of the nano-titanium dioxide particles with a surface-coated zinc oxide conductive layer doped with Ce is chemical co-precipitation, including the following steps: S21. Add zinc chloride and cerium chloride to hydrochloric acid solution, stir well to dissolve, and obtain a mixed solution; S22. Add deionized water to titanium dioxide particles, stir ultrasonically for 12 min to make titanium dioxide and deionized water miscible, and obtain a titanium dioxide suspension; S23. Drop the mixed solution of S21 into the titanium dioxide suspension, and at the same time drop sodium hydroxide solution, and keep stirring to promote the reaction. After dropping, keep the reaction at a constant temperature for 1.5 h; S24. Filter, wash, dry, grind and calcine the obtained reactants to obtain nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The particle size range of the modified nano-titanium dioxide particles is 10 - 100 nm; The particle size of the river sand is 1 - 5 mm, and the particle size of the crushed stone is 5 - 20 mm; The preparation method of the high-strength conductive concrete includes the following steps: S1. Add water to the modified nano-titanium dioxide particles, stir ultrasonically for 14 min to obtain a uniformly dispersed suspension; S2. Weigh the corresponding weights of fly ash, river sand and steel fibers, pour them into a mixer and dry mix for 2 min to obtain a uniform primary mixture; S3. Add the corresponding weights of river sand and cement to the primary mixture and dry mix for 3 min to obtain a secondary mixture; S4. Add the corresponding weights of the suspension, water reducing agent and water to the secondary mixture, and wet mix for 9 min to obtain concrete. Example 5: A high-strength conductive concrete, comprising the following components by weight ratio: Portland cement: 395 parts; Water: 205 parts; River sand: 815 parts; Crushed stone: 885 parts; Fly ash: 139 parts; Polycarboxylic acid water reducing agent: 6 parts; Surface-modified steel fibers: 45 parts; Modified nano-titanium dioxide particles: 10 parts; The surface-modified steel fibers are steel fibers coated with nano-zinc oxide; The preparation method of the nano-zinc oxide-coated steel fibers is electrophoretic deposition method, including the following steps: S11. Clean the steel fibers. First, use anhydrous ethanol to rinse off the grease and other impurities on the surface of the steel fibers, then use deionized water to rinse until the pH value is neutral, and dry at room temperature; S12. Prepare a suspension by adding zinc oxide nanoparticles to deionized water at a concentration of 0.07 wt%, and disperse it ultrasonically for 15 min; S13. Electrophoretic deposition: Place steel fibers as the cathode material into the suspension, apply a direct current of 6 V, and process for 7 min; S14. Wash and dry: Take out the treated steel fibers, rinse them thoroughly with deionized water, place them in an oven for drying, with a drying temperature of 62 °C and a drying time of 24 h; The morphology of the surface-modified steel fibers includes straight, end-hooked, and wavy shapes; The surface-modified steel fibers include long fibers and short fibers. The length range of the long fibers is 20 - 40 mm, the equivalent diameter range is 0.3 - 0.6 mm, and the aspect ratio is between 50 - 80; the length range of the short fibers is 5 - 10 mm, the equivalent diameter range is 0.2 - 0.4 mm, and the aspect ratio is between 10 - 25; The modified nano-titanium dioxide particles are nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The preparation method of the nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface is the chemical co-precipitation method, which includes the following steps: S21. Add zinc chloride and cerium chloride to hydrochloric acid solution, stir well to dissolve, and obtain a mixed solution; S22. Add deionized water to the titanium dioxide particles, stir ultrasonically for 9 min to make the titanium dioxide and deionized water miscible, and obtain a titanium dioxide suspension; S23. Drop the mixed solution of S21 into the titanium dioxide suspension, while dropping sodium hydroxide solution, and keep stirring to promote the reaction. After dropping, keep the reaction at a constant temperature for 1.2 h; S24. Filter, wash, dry, grind, and calcine the obtained reactants to obtain nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The particle size range of the modified nano-titanium dioxide particles is 10 - 100 nm; The particle size of the river sand is 1 - 5 mm, and the particle size of the crushed stone is 5 - 20 mm; The preparation method of the high-strength conductive concrete includes the following steps: S1. Add water to the modified nano-titanium dioxide particles, stir ultrasonically for 13 min to obtain a uniformly dispersed suspension; S2. Weigh the corresponding weights of fly ash, river sand, and steel fibers, pour them into a mixer and dry-mix for 2 min to obtain a uniform primary mixture; S3. Add the corresponding weights of river sand and cement to the primary mixture and dry-mix for 4 min to obtain a secondary mixture; S4. Add the corresponding weights of the suspension, water-reducing agent, and water to the secondary mixture and wet-mix for 8 min to obtain concrete. Comparative Example 1: A conductive concrete, comprising the following components by weight ratio: Portland cement: 390 parts; Water: 210 parts; River sand: 810 parts; Crushed stone: 890 parts; Fly ash: 137 parts; Polycarboxylate superplasticizer: 8 parts; Steel fiber: 42 parts; Modified nano-titanium dioxide particles: 13 parts; The morphology of the steel fiber includes straight, end-hooked and wavy shapes; The steel fiber includes long fibers and short fibers. The length range of the long fibers is 20 - 40 mm, the equivalent diameter range is 0.3 - 0.6 mm, and the aspect ratio is between 50 - 80; the length range of the short fibers is 5 - 10 mm, the equivalent diameter range is 0.2 - 0.4 mm, and the aspect ratio is between 10 - 25; The modified nano-titanium dioxide particles are nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The preparation method of the nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface is the chemical co-precipitation method, including the following steps: S21. Add zinc chloride and cerium chloride to the hydrochloric acid solution, stir and dissolve thoroughly to obtain a mixed solution; S22. Add deionized water to the titanium dioxide particles, ultrasonically stir for 13 min to make the titanium dioxide and deionized water miscible, and obtain a titanium dioxide suspension; S23. Drop the mixed solution of S21 into the titanium dioxide suspension, and at the same time drop the sodium hydroxide solution, and keep stirring to promote the reaction. After dropping, keep the reaction at a constant temperature for 1.4 h; S24. Filter, wash, dry, grind and calcine the obtained reactants to obtain nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The particle size range of the modified nano-titanium dioxide particles is 10 - 100 nm; The particle size of the river sand is 1 - 5 mm, and the particle size of the crushed stone is 5 - 20 mm; The preparation method of the high-strength conductive concrete includes the following steps: S1. Add water to the modified nano-titanium dioxide particles, ultrasonically stir for 12 min to obtain a uniformly dispersed suspension; S2. Weigh the corresponding weights of fly ash, river sand and steel fiber, pour them into a mixer and dry mix for 1 min to obtain a uniform primary mixture; S3. Add the corresponding weights of river sand and cement to the primary mixture and dry mix for 4 min to obtain a secondary mixture; S4. Add the corresponding weights of suspension, water reducing agent and water to the secondary mixture, and wet mix for 8 min to obtain concrete. Comparative Example 2: A conductive concrete, comprising the following components by weight ratio: Portland cement: 395 parts; Water: 205 parts; River sand: 805 parts; Crushed stone: 895 parts; Fly ash: 140 parts; Polycarboxylate water reducing agent: 5 parts; Surface-modified steel fibers: 41 parts; Nanometer titanium dioxide particles: 14 parts; The surface-modified steel fibers are steel fibers coated with nanometer zinc oxide; The preparation method of the steel fibers coated with nanometer zinc oxide is electrophoretic deposition method, comprising the following steps: S11. Clean the steel fibers. First, rinse off the grease and other impurities on the surface of the steel fibers with anhydrous ethanol, and then rinse with deionized water until the pH value is neutral, and dry at room temperature; S12. Prepare a suspension. Add nanometer zinc oxide to deionized water with a concentration of 0.05 wt%, and use ultrasonic dispersion for 11 min; S13. Electrophoretic deposition. Place the steel fibers as the cathode material into the suspension, and pass a direct current of 4 V for 13 min; S14. Clean and dry. Take out the treated steel fibers, rinse them with deionized water, put them into an oven for drying, the drying temperature is 68 °C, and the drying time is 20 h; The morphology of the surface-modified steel fibers includes straight shape, end-hook shape and wavy shape; The surface-modified steel fibers include long fibers and short fibers. The length range of the long fibers is 20 - 40 mm, the equivalent diameter range is 0.3 - 0.6 mm, and the aspect ratio is between 50 - 80; the length range of the short fibers is 5 - 10 mm, the equivalent diameter range is 0.2 - 0.4 mm, and the aspect ratio is between 10 - 25; The particle size range of the nanometer titanium dioxide particles is 10 - 100 nm; The particle size of the river sand is 1 - 5 mm, and the particle size of the crushed stone is 5 - 20 mm; The preparation method of the high-strength conductive concrete comprises the following steps: S1. Add water to the nanometer titanium dioxide particles, and stir ultrasonically for 14 min to obtain a uniformly dispersed suspension; S2. Weigh the corresponding weight of fly ash, river sand and steel fiber, pour into the mixer and dry mix for 2 minutes to obtain a uniform primary mixture; S3. Add the corresponding weight of river sand and cement to the primary mixture, dry mix for 5 minutes to obtain a secondary mixture; S4. Add corresponding weights of suspension, water reducing agent and water to the secondary mixture and wet mix for 10 minutes to obtain concrete. Comparative Example 3: A conductive concrete comprising the following components in weight ratio: Portland cement: 395 parts; Water: 205 parts; River sand: 810 parts; Crushed stone: 890 pieces; Fly ash: 137 parts; Polycarboxylate water reducer: 8 parts; Surface modified steel fiber: 45 parts; Modified nano titanium dioxide particles: 10 parts; The surface modified steel fiber is a nano zinc oxide coated steel fiber; The preparation method of the nano zinc oxide coated steel fiber is an electrophoretic deposition method, comprising the following steps: S11. Cleaning the steel fiber, first use anhydrous ethanol to rinse off impurities such as grease on the surface of the steel fiber, then use deionized water to rinse until the pH value is neutral, and dry at room temperature; S12. Prepare a suspension, add nano zinc oxide to deionized water at a concentration of 0.07wt%, and use ultrasonic dispersion for 18min; S13. Electrophoretic deposition, put steel fiber as a cathode material into the suspension, pass 5V DC, and treat for 10min; S14. Cleaning and drying, remove the treated steel fiber, rinse with deionized water, put into an oven for drying, drying temperature 65 ° C, drying time 22h; The surface modified steel fiber is a straight long fiber with a length ranging from 20 to 40 mm, an equivalent diameter ranging from 0.3 to 0.6 mm, and an aspect ratio between 50 and 80; The modified nano titanium dioxide particles are nano titanium dioxide particles with a surface coated with a Ce-doped zinc oxide conductive layer; The preparation method of the nano titanium dioxide particles with a surface-coated Ce-doped zinc oxide conductive layer is a chemical coprecipitation method, comprising the following steps: S21. Add zinc chloride and cerium chloride to the hydrochloric acid solution, stir and dissolve to obtain a mixed solution; S22. Deionized water was added to the titanium dioxide particles and ultrasonically stirred for 10 min to dissolve the titanium dioxide and deionized water to obtain a titanium dioxide suspension; S23. Drop the mixed solution of S21 into the titanium dioxide suspension, while dropping the sodium hydroxide solution, and keep stirring to promote the reaction. After dropping, keep the reaction at a certain temperature for 1.2 h. S24. Filter, wash, dry, grind and calcine the obtained reactants to obtain nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface. The particle size range of the modified nano-titanium dioxide particles is 10 - 100 nm. The particle size of the river sand is 1 - 5 mm, and the particle size of the crushed stone is 5 - 20 mm. The preparation method of the high-strength conductive concrete includes the following steps: S1. Add water to the modified nano-titanium dioxide particles and stir ultrasonically for 13 min to obtain a uniformly dispersed suspension. S2. Weigh the corresponding weights of fly ash, river sand and steel fibers, pour them into a mixer and dry mix for 3 min to obtain a uniform primary mixture; S3. Add the corresponding weights of river sand and cement to the primary mixture and dry mix for 5 min to obtain a secondary mixture. S4. Add the corresponding weights of the suspension, water reducing agent and water to the secondary mixture and wet mix for 6 min to obtain the concrete. Comparative Example 4: A conductive concrete, comprising the following components by weight ratio: Portland cement: 375 parts; Water: 210 parts; River sand: 815 parts; Crushed stone: 885 parts; Fly ash: 135 parts; Polycarboxylate water reducing agent: 10 parts; Surface-modified steel fibers: 40 parts; Modified nano-titanium dioxide particles: 30 parts; The surface-modified steel fibers are steel fibers coated with nano-zinc oxide. The preparation method of the nano-zinc oxide-coated steel fibers is electrophoretic deposition, including the following steps: S11. Clean the steel fibers. First, use anhydrous ethanol to rinse off the grease and other impurities on the surface of the steel fibers, then use deionized water to rinse until the pH value is neutral, and dry at room temperature. S12. Prepare the suspension. Add nano-zinc oxide to deionized water with a concentration of 0.06 wt%, and disperse ultrasonically for 13 min; S13. Electrophoretic deposition. Put the steel fibers as the cathode material into the suspension, and apply 3 V direct current for 9 min. S14. Wash and dry. Take out the treated steel fibers, rinse them with deionized water, put them into an oven to dry, the drying temperature is 69 °C, and the drying time is 24 h. The morphology of the surface-modified steel fibers includes straight, end-hooked, and wavy shapes; The surface-modified steel fibers include long fibers and short fibers. The length range of the long fibers is 20 - 40 mm, the equivalent diameter range is 0.3 - 0.6 mm, and the length-to-diameter ratio is between 50 and 80; the length range of the short fibers is 5 - 10 mm, the equivalent diameter range is 0.2 - 0.4 mm, and the length-to-diameter ratio is between 10 and 25; The modified nano-titanium dioxide particles are nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The preparation method of the nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface is the chemical co-precipitation method, which includes the following steps: S21. Add zinc chloride and cerium chloride to the hydrochloric acid solution, stir well to dissolve, and obtain a mixed solution; S22. Add deionized water to the titanium dioxide particles, stir ultrasonically for 20 min to make the titanium dioxide and deionized water miscible, and obtain a titanium dioxide suspension; S23. Drop the mixed solution of S21 into the titanium dioxide suspension, and at the same time drop the sodium hydroxide solution, and keep stirring to promote the reaction. After dropping, keep the reaction at a constant temperature for 2.0 h; S24. Filter, wash, dry, grind, and calcine the obtained reactants to obtain nano-titanium dioxide particles with a zinc oxide conductive layer doped with Ce on the surface; The particle size range of the modified nano-titanium dioxide particles is 10 - 100 nm; The particle size of the river sand is 1 - 5 mm, and the particle size of the crushed stone is 5 - 20 mm; The preparation method of the high-strength conductive concrete includes the following steps: S1. Add water to the modified nano-titanium dioxide particles, stir ultrasonically for 15 min to obtain a uniformly dispersed suspension; S2. Weigh the corresponding weights of fly ash, river sand, and steel fibers, pour them into a mixer and dry mix for 1 min to obtain a uniform primary mixture; S3. Add the corresponding weights of river sand and cement to the primary mixture and dry mix for 3 min to obtain a secondary mixture; S4. Add the corresponding weights of the suspension, water reducer, and water to the secondary mixture and wet mix for 9 min to obtain the concrete. Perform mechanical property and resistivity tests on the concrete of the examples and comparative examples. The test piece sizes for tensile strength and compressive strength are 100 mm × 100 mm × 100 mm, and the test piece size for flexural strength is 100 mm × 100 mm × 400 mm. The two-electrode method of a DC power supply is used for resistance testing, and the resistance of the test piece can be measured. The resistivity can be obtained through conversion. Name Tensile strength / MPa Compressive strength / MPa Flexural strength / MPa Resistivity / Ω·cm Example 1 3.50 37.56 4.35 856 Example 2 3.92 34.79 4.77 305 Example 3 3.79 35.13 5.56 451 Example 4 3.56 37.05 4.96 608 Example 5 3.67 36.37 5.28 393 Comparative example 1 2.99 32.59 3.82 312 Comparative example 2 3.32 34.28 3.44 917 Comparative example 3 2.78 30.97 3.07 533 Comparative example 4 3.25 29.13 4.11 729 In summary, compared with the comparative example, the conductive concrete prepared by the present invention not only has a lower resistivity, but also has improved tensile, compressive and flexural strengths, and has excellent comprehensive mechanical properties. Moreover, the modification process of the fibers and particles is simple, the coating quality is high, the preparation process of the concrete takes a short time, and the fibers and particles have good dispersibility.

Claims

1. A high-strength conductive concrete, characterized in that: The high-strength conductive concrete comprises the following components by weight: Portland cement: 380-400 parts; Water: 200-220 parts; River sand: 800-820 parts; Crushed stone: 880-900 parts; Fly ash: 135-140 parts; Polycarboxylate water reducer: 5-10 parts; Surface modified steel fiber: 40-50 parts; Modified nano titanium dioxide particles: 5 to 15 parts.

2. The high-strength conductive concrete according to claim 1, characterized in that: The surface modified steel fiber is a nano zinc oxide coated steel fiber.

3. The high-strength conductive concrete according to claim 1, characterized in that: The preparation method of the nano zinc oxide coated steel fiber is an electrophoretic deposition method, comprising the following steps: S11. Cleaning the steel fiber, first use anhydrous ethanol to rinse off impurities such as grease on the surface of the steel fiber, then use deionized water to rinse until the pH value is neutral, and dry at room temperature; S12. Prepare a suspension by adding nano zinc oxide to deionized water at a concentration of 0.05 to 0.1 wt %, and use ultrasonic dispersion for 10 to 20 min; S13. Electrophoretic deposition: steel fiber is placed in the suspension as cathode material, and 3-7V direct current is applied for 5-15min; S14. Cleaning and drying: taking out the treated steel fiber, rinsing it with deionized water, and drying it in an oven at a temperature of 60 to 70° C. for 20 to 25 hours.

4. The high-strength conductive concrete according to claim 1, characterized in that: The surface modified steel fiber shapes include straight shape, end hook shape and wavy shape.

5. The high-strength conductive concrete according to claim 1, characterized in that: The surface modified steel fiber includes long fibers and short fibers. The long fibers have a length range of 20 to 40 mm, an equivalent diameter range of 0.3 to 0.6 mm, and an aspect ratio of 50 to 80. The short fibers have a length range of 5 to 10 mm, an equivalent diameter range of 0.2 to 0.4 mm, and an aspect ratio of 10 to 25.

6. The high-strength conductive concrete according to claim 1, characterized in that: The modified nano titanium dioxide particles are nano titanium dioxide particles with a surface coated with a Ce-doped zinc oxide conductive layer.

7. The high-strength conductive concrete according to claim 1, characterized in that: The preparation method of the nano titanium dioxide particles with a surface-coated Ce-doped zinc oxide conductive layer is a chemical coprecipitation method, comprising the following steps: S21. Add zinc chloride and cerium chloride to the hydrochloric acid solution, stir and dissolve to obtain a mixed solution; S22. Deionized water was added to the titanium dioxide particles and ultrasonically stirred for 5 to 15 min to dissolve the titanium dioxide and deionized water to obtain a titanium dioxide suspension; S23. The mixed solution of S21 is dropped into the titanium dioxide suspension, and sodium hydroxide solution is added dropwise while stirring to promote the reaction. After the addition is complete, the reaction is kept warm for 1 to 1.5 hours; S24. The obtained reactant is filtered, washed, dried, ground and calcined to obtain nano titanium dioxide particles with a surface-coated Ce-doped zinc oxide conductive layer.

8. The high-strength conductive concrete according to claim 1, characterized in that: The particle size of the modified nano titanium dioxide particles ranges from 10 to 100 nm.

9. The high-strength conductive concrete according to claim 1, characterized in that: The particle size of the river sand is 1 to 5 mm, and the particle size of the crushed stone is 5 to 20 mm.

10. The high-strength conductive concrete according to claim 1, characterized in that: The preparation method of the high-strength conductive concrete comprises the following steps: S1. Add water to the modified nano-titanium dioxide particles and stir ultrasonically for 10 to 15 minutes to obtain a uniformly dispersed suspension; S2. Weigh the corresponding weight of fly ash, river sand and steel fiber, pour them into a mixer and dry mix for 1 to 3 minutes to obtain a uniform primary mixture; S3. Add corresponding weight of river sand and cement to the primary mixture and dry mix for 3 to 5 minutes to obtain a secondary mixture; S4. Add corresponding weights of suspension, water reducing agent and water to the secondary mixture and wet mix for 5 to 10 minutes to obtain concrete.