A bimodal response white concrete and its preparation and repair method

Abstract

The application relates to the field of high-performance building materials, and particularly discloses a bimodal response fair-faced concrete and a preparation and repair method thereof. The bimodal response fair-faced concrete comprises cement, water, sand, stone and microcapsules; the microcapsules comprise the following components: 35%-45% silicate, 30%-35% acrylate, 1.5%-2.5% tungsten oxide, 1%-5% micro-nano particles, 4-8% polyaniline, 1%-3% ionic surfactant, and the balance is titanium dioxide. The application realizes the bimodal response function through a microcapsule system, wherein the silicate and the acrylate provide a chemical repair basis, the polyaniline constructs an electrically conductive network, the tungsten oxide realizes electrochromic indication, the titanium dioxide endows self-cleaning capability, a fair-faced concrete system with repair and intelligent response characteristics is formed, and the problem of microcracks is effectively solved.

Description

Technical Field

[0001] This application relates to the field of high-performance building materials, and more specifically, to a bimodal responsive fair-faced concrete and methods for its preparation and repair. Background Technology

[0002] Fair-faced concrete, as a high-end form of expression widely used in modern architecture, is favored by architects and engineers for its simple, natural, dignified, and elegant decorative effect, as well as the economic and environmental advantages of eliminating secondary decorative construction such as plastering and ceilings. Its final surface forms the building facade, directly exposed to the external environment, thus placing extremely high demands on the concrete's appearance quality, durability, and long-term performance.

[0003] However, as a porous, heterogeneous, and brittle material, concrete's inherent properties make it highly susceptible to various forms of cracking during hardening and use. Among these, microcracks (typically referring to cracks less than 0.2 mm in width) are particularly prominent and prevalent.

[0004] Currently, the control and treatment of microcracks in fair-faced concrete mainly involves using high-strength grout or cement paste to smooth the surface, which easily leads to secondary cracking. This "remedial" approach often sacrifices the original appearance of the fair-faced concrete or fails to address new cracks that continue to appear throughout its service life. Therefore, developing a technology that can repair microcracks as they appear is crucial for improving the long-term durability of fair-faced concrete. Summary of the Invention

[0005] In order to ensure the quality and efficiency of crack repair in fair-faced concrete, this application provides a dual-modal response fair-faced concrete and its preparation and repair method.

[0006] Firstly, this application provides a dual-modal responsive fair-faced concrete, employing the following technical solution: A bimodal responsive fair-faced concrete comprises the following raw materials in parts by weight: Cement: 280-320 parts; Water: 105-110 parts; Sand: 520-540 parts; Stone: 720-780 portions; Microcapsules: 3-5 servings; The microcapsules comprise the following components: 35%-45% silicate, 30%-35% acrylate, 1.5%-2.5% tungsten oxide, 1%-5% micro / nano particles, 4-8% polyaniline, 1%-3% ionic surfactant, with the balance being titanium dioxide.

[0007] By adopting the above technical solution, a dual-modal approach is used to repair concrete, as detailed below: Mode 1 (Chemical Response): When microcracks develop in concrete, the stress at the crack tip causes the microcapsules to rupture, releasing the repair agents (silicates, acrylates, etc.) inside. These repair agents solidify upon encountering moisture and air in the cracks, forming a binder that automatically fills and seals the microcracks. Mode 2 (electrochemical response): Polyaniline and tungsten oxide in the microcapsules serve as the conductive and electrochromic phases, respectively, while titanium dioxide imparts self-cleaning capabilities, forming a fair-faced concrete system that combines repair and intelligent response characteristics, effectively solving the problem of microcracks.

[0008] Preferably, it also includes conductive composite fibers, which are composed of carbon nanofibers and steel fibers in a weight ratio of 1:(2-3), wherein the aspect ratio of the carbon nanofibers is greater than or equal to 1000, and the aspect ratio of the steel fibers is greater than or equal to 20.

[0009] By adopting the above technical solution, a multi-scale conductive network is constructed by combining carbon nanofibers (≥1000) and steel fibers (≥20). The carbon nanofibers form microscopic conductive pathways, while the steel fibers provide macroscopic reinforcing skeletons. The two work together to significantly improve the conductivity, mechanical properties, and durability of concrete, and provide a stable current path for electro-excitation repair.

[0010] Preferably, it also includes 4-6 parts of fine expanded fibers, wherein the fine expanded fibers are selected from any one of polyacrylamide-grafted polyaniline, sodium polyacrylate, and hydrophilic polyurethane.

[0011] By adopting the above technical solution and adding fine expansion fibers, moderate expansion stress is generated inside the concrete to actively compensate for shrinkage deformation. The fibers can be selected from three polymer materials, all of which can effectively inhibit the generation of plastic shrinkage and drying shrinkage cracks, reduce crack formation from the source, and form a complementary protection system with microcapsule repair.

[0012] Preferably, the fine expanded fibers are polyacrylamide-grafted polyaniline.

[0013] By adopting the above technical solution, polyacrylamide grafted with polyaniline is preferred as the expanding fiber. Its polyacrylamide segments provide excellent hydrophilic expansion properties, and the polyaniline segments participate in the construction of the conductive network, realizing the molecular-level synergy of expansion function and conductivity function, while playing a dual role of crack resistance and strengthening the conductive network.

[0014] Preferably, it also includes 6-10 parts of WO3@aggregate.

[0015] By adopting the above technical solution and introducing WO3@aggregate, concrete damage is given a visual indication function. Under the action of an electric field, WO3 in the damaged area undergoes an electrochromic reaction, and the location of the crack is intuitively displayed through color change. At the same time, it can also be used as an intelligent energy-saving component to realize adaptive dimming of building facades and improve functional integration.

[0016] Secondly, this application provides a method for preparing dual-modal responsive fair-faced concrete, employing the following technical solution: A method for preparing dual-modal responsive fair-faced concrete includes the following steps: (1) First, put sand, stone, cement and WO3@ aggregate into the mixer and mix them evenly; (2) After dry mixing evenly, add water and finely expanded fibers; (3) Finally, add microcapsules and conductive composite fibers.

[0017] By adopting the above technical solution and employing a step-by-step feeding process, aggregates and cement are mixed first, then water and expanded fibers are added, and finally functional components are added. This sequence ensures that the microcapsules and conductive fibers are not damaged, guarantees uniform dispersion of functional components, optimizes the interface structure, and improves the overall performance and construction feasibility of the system.

[0018] Thirdly, this application provides a method for repairing dual-modal response fair-faced concrete, employing the following technical solution: energizing the concrete with a current of 0.5-1.5 mA / mm². 2 The repair of the crack can be completed in 0.5-2 hours.

[0019] By adopting the above technical solution, the electrochemical repair mechanism is activated by excitation with a current of 0.5-1.5mA / mm², and calcium carbonate is deposited under the action of an electric field to effectively fill the cracks. This method, together with chemical repair, provides a dual guarantee, enabling on-demand and precise crack repair without damaging the original concrete finish and maintaining the aesthetic value of fair-faced concrete.

[0020] Fourthly, this application provides a microcapsule, employing the following technical solution: A microcapsule, characterized in that it is composed of the following components: 35%-45% silicates, 30%-35% acrylates, 1.5%-2.5% tungsten oxide, 1%-5% micro / nano particles, 4-8% polyaniline, 1%-3% ionic surfactants, with the balance being titanium dioxide. By adopting the above technical solution, the microcapsule design integrates repair agent, conductive agent and indicator into one, silicate and acrylate provide repair matrix, polyaniline establishes conductive pathway, tungsten oxide realizes visualization, and titanium dioxide protects the system. The components work together to realize the response cycle of sensing-indication-repair.

[0021] In summary, this application has the following beneficial effects: 1. This application achieves dual-modal response function through a microcapsule system, in which silicates and acrylates provide the basis for chemical repair, polyaniline constructs a conductive network, tungsten oxide realizes electrochromic indication, and titanium dioxide imparts self-cleaning ability, forming a fair-faced concrete system with both repair and intelligent response characteristics, effectively solving the problem of microcracks; 2. This application activates the electrochemical repair mechanism by excitation with a current of 0.5-1.5mA / mm², which induces calcium carbonate deposition under the action of an electric field, effectively filling the cracks. This method, together with chemical repair, provides a dual guarantee, enabling on-demand and precise crack repair without damaging the original concrete finish and maintaining the aesthetic value of fair-faced concrete. 3. The microcapsule design of this application integrates repair agent, conductive agent and indicator into one unit. Silicate and acrylate provide repair matrix, polyaniline establishes conductive pathway, tungsten oxide realizes visualization, and titanium dioxide protects the system. The components work together to realize the response cycle of sensing-indication-repair. Detailed Implementation

[0022] The present application will be further described in detail below with reference to the embodiments.

[0023] Performance testing experiment Concrete samples obtained from each embodiment and comparative example were selected and prepared into corresponding specimens. Their crack self-healing rate, electrical conductivity, drying shrinkage, compressive strength, and slump were tested. The testing methods and steps for each property are as follows: 1. Crack self-healing rate: Pre-cracking-self-healing-reloading method (custom, based on academic common methods) Pre-cracking: A concrete specimen (such as a prism) cured for 28 days is loaded on a testing machine to 70% of its flexural strength, inducing a single crack with a width of 0.3 mm.

[0024] Initial measurement: The initial width W0 of the crack was accurately measured using a crack observation instrument. Self-healing curing: The cracked specimens were placed under standard curing conditions (temperature 20±2°C, humidity ≥95%) for 7 days. For the present invention group, DC 3-5V electrode stimulation could be applied at the beginning of curing.

[0025] Final measurement: The crack width W1 was measured again after 7 days.

[0026] Calculation: Crack self-healing rate = [(W0-W1) / W0] × 100% Electrical conductivity: Refer to ASTM C1760, "Method for testing the resistivity of concrete surfaces". Test procedure: Electrodes were installed on opposite sides of the concrete specimen after 28 days of curing to measure its resistance value, and the volume conductivity was calculated based on the specimen size.

[0027] 3. Drying shrinkage: Refer to ASTM C157 Test procedure: After the concrete specimens are cured to the specified age under standard conditions, they are moved into a constant temperature (20±2°C) and constant humidity (50±5% RH) environment, and their length changes are measured periodically.

[0028] 4. Compressive strength: Refer to ASTM C39 Test procedure: Place concrete test blocks (standard size: 150mm×150mm×150mm) cured to the specified age (3 days, 28 days) in the center of the bearing plate of the testing machine, and load them at a constant rate (0.5-0.8MPa / s) until the test block fails, and record the maximum load.

[0029] 5. Slump: Refer to ASTM C143 Test procedure: Freshly mixed concrete was poured into a slump cone in three layers, with each layer tamped 25 times. After smoothing, the cone was lifted vertically, and the difference between the highest point of the slumped concrete and the height of the cone was measured.

[0030] Preparation Examples 1-3 The components and amounts of the raw materials used in a microcapsule are shown in the table below (kg).

[0031] The micro- and nano-particles in the table above are nano-clays, and the ionic surfactant is dodecyl dimethyl betaine.

[0032] Examples 1-3 A dual-modal responsive fair-faced concrete, the components and amounts of its raw materials are shown in the table below (kg), and it is prepared using the following steps: (1) First, put sand, stone, cement and WO3@ aggregate into the mixer according to the corresponding weight ratio and mix them evenly. The sand particle size is 0.8 mm, the stone particle size is 15 mm, the cement is silicate cement, and the WO3@ aggregate particle size is 8 mm. (2) After dry mixing, add the corresponding weight of water and fine expanded fibers, wherein the fine expanded fibers are polyacrylamide grafted polyaniline; (3) Finally, add the corresponding weight of microcapsules and conductive composite fibers to obtain the product. The microcapsules are prepared by Preparation Example 1, and the conductive composite fibers are made by mixing nanofibers and steel fibers in a weight ratio of 1:2.5.

[0033]

[0034] Examples 4-5 A dual-modal responsive fair-faced concrete differs from Example 1 in that the selection of microcapsules is different, and the specific correspondence is shown in the table below.

[0035] Table 3: Comparison of Microcapsule Usage in Examples 4-5

[0036] Comparative Example 1 A type of fair-faced concrete differs from Example 1 in that it does not contain microcapsules.

[0037] Comparative Example 2 The difference between this type of fair-faced concrete and Example 1 is that the composition of the microcapsules is different. The composition is: 35% silicate, 30% acrylate, 1.5% tungsten oxide, 1% micro / nano particles, 1% ionic surfactant, and 27.5% titanium dioxide.

[0038] Comparative Example 3 A type of fair-faced concrete differs from Example 1 in that the composition of the microcapsules is different, consisting of: 35% silicate, 30% acrylate, 1% micro / nano particles, 4% polyaniline, 1% ionic surfactant, and 27.5% titanium dioxide.

[0039] Comparative Example 4 The difference between this type of fair-faced concrete and Example 1 is that the composition of the microcapsules is different. The composition is: 35% silicate, 1.5% tungsten oxide, 1% micro / nano particles, 4% polyaniline, 1% ionic surfactant, and 27.5% titanium dioxide.

[0040] Comparative Example 5 The difference between this type of fair-faced concrete and Example 1 is that the composition of the microcapsules is different. The composition is: 35% silicate, 30% acrylate, 1.5% tungsten oxide, 1% micro / nano particles, 4% polyaniline, and 27.5% titanium dioxide.

[0041] Concrete samples prepared in Examples 1-5 and Comparative Examples 1-5 were selected as test objects, and their crack self-healing rate, electrical conductivity, drying shrinkage, compressive strength, and slump were tested respectively. The average value of the test results was recorded in the table below.

[0042]

[0043] As shown in Table 4, the fair-faced concrete in Examples 1-3, benefiting from its component proportions and the mechanism of bimodal response, exhibits excellent performance in various aspects. Its slump is 165-185 mm, 3-day compressive strength is 28.5-31.6 MPa, 28-day compressive strength is 52.3-56.5 MPa, crack self-healing rate is 88.0-92.0%, electrical conductivity is 0.045-0.051 S / m, and drying shrinkage is 365 × 10⁻⁶ mm. -6 -380×10 -6 ; Further analysis shows that when the amount of microcapsule added increases from 3 parts to 5 parts, the strength and self-healing rate of concrete steadily improve, drying shrinkage is significantly reduced, and electrical conductivity increases slightly.

[0044] The reasons are analyzed as follows: more microcapsules provide richer repair agents (acrylates / silicates), thereby improving the repair ability; the micro- and nano-particles (nanoclay) and silicates in the microcapsules optimize the slurry structure, playing a role in reinforcement and densification, thus increasing strength and reducing shrinkage; the content of polyaniline in the microcapsules is fixed, so the increase in total doping makes the conductive pathway more complete, and the conductivity rises slowly; the increase in solid phase components leads to an increase in water demand, thus the slump decreases accordingly.

[0045] A comparison of Examples 1, 4, and 5 shows that the microcapsules of Example 4 exhibit the best performance, with higher strength, repair rate, and conductivity than those of Example 1. Conversely, the microcapsules of Example 5 show decreased performance, with higher slump but lower strength and repair rate, and increased shrinkage. The possible reasons for this are as follows: The formulation in Example 4 was the most balanced, with moderate contents of polyaniline (6%) and micro / nano particles (3%), providing good conductivity and reinforcement. Although Preparation Example 3 had the highest polyaniline content (8%) and the highest conductivity, the titanium dioxide content was too low (1.5%), resulting in insufficient UV protection for the polymer (acrylate) and polyaniline. Furthermore, the total proportion of the repair agent decreased relatively, affecting its overall durability and repair effect.

[0046] As for Comparative Examples 1-5, their performance decreased to varying degrees compared to Examples 1-5. The reasons for this are analyzed below: Comparative Example 1 (without microcapsules): Almost all functional properties (self-healing, electrical conductivity) were lost, and the shrinkage was the greatest, proving that microcapsules play a major role in realizing the sensing-indication-repair response cycle.

[0047] Comparative Example 2 (without polyaniline): The electrical conductivity plummeted, and the self-healing rate of the cracks decreased significantly (only chemical repair remained), proving that polyaniline is the core of conductive and electrically stimulated repair.

[0048] Comparative Example 3 (without tungsten oxide): The performance is very close to that of Example 1, proving that tungsten oxide mainly plays an indicative role in this system and has little impact on the core performance.

[0049] Comparative Example 4 (without acrylate): The self-healing rate of the crack was severely impaired, proving that acrylate is the main carrier of chemical repair agents.

[0050] Comparative Example 5 (without surfactant): The lowest slump, decreased electrical conductivity and crack self-healing rate, demonstrating that surfactants are crucial for ensuring uniform component dispersion and maintaining workability and functional uniformity.

[0051] Implementation 6-8 The difference between this dual-modal responsive fair-faced concrete and Example 1 is that it also includes conductive composite fibers, and the weights of its components are shown in the table below.

[0052]

[0053] The conductive composite fiber in Table 5 is made by mixing carbon nanofibers and steel fibers in a weight ratio of 1:2.5. The aspect ratio of the carbon nanofibers is 1000, and the aspect ratio of the steel fibers is 20.

[0054] The concrete prepared in Examples 6-8 above was selected as the test object, and its crack self-healing rate, electrical conductivity, drying shrinkage, compressive strength and slump were tested respectively. The average value of the test results was recorded in the table below.

[0055]

[0056] Table 6 shows that the slump is 150-170 mm, the 3-day compressive strength is 31.5-35.2 MPa, the 28-day compressive strength is 56.8-62.5 MPa, the self-healing rate of cracks is 90.5-94.0%, the electrical conductivity is 0.123-0.195 S / m, and the drying shrinkage is 365 × 10⁻⁶ MPa. -6 -375×10 -6 .

[0057] The dosage of conductive composite fibers significantly affects the overall performance. When the dosage is 15 parts (Example 7), the concrete achieves the best performance: the 28-day compressive strength reaches 62.5 MPa, the electrical conductivity increases to 0.195 S / m, and the self-healing rate reaches 94%. This is attributed to the formation of the most effective fiber-conductive network synergistic reinforcement system at this dosage. When the dosage is increased to 18 parts, the various properties decline due to fiber agglomeration.

[0058] Implementation 9-10 The difference between the dual-modal responsive fair-faced concrete and Example 7 is that the ratio of carbon nanofibers to steel fibers in the conductive composite fiber is different, as shown in the table below.

[0059]

[0060] The concrete prepared in Examples 9-10 above was selected as the test object, and its crack self-healing rate, electrical conductivity, drying shrinkage, compressive strength and slump were tested respectively. The average value of the test results was recorded in the table below.

[0061]

[0062] As shown in Table 8, the fair-faced concrete in Examples 9-10 exhibits excellent performance across various parameters. Its slump is 158-162 mm, its 3-day compressive strength is 33.5-34.2 MPa, its 28-day compressive strength is 59.0-60.2 MPa, its crack self-healing rate is 92.0-93.2%, its electrical conductivity is 0.168-0.182 S / m, and its drying shrinkage is 365 × 10⁻⁶. -6 -370×10 -6 .

[0063] With a fixed total fiber content (15 parts), comparisons of different weight ratios show that Example 7 (1:2.5) exhibits the best overall performance, with a 28-day strength of 62.5 MPa, an electrical conductivity of 0.195 S / m, and a self-healing rate of 94.0%, all higher than Examples 9 (1:2) and 10 (1:3). This result indicates that when the weight ratio of carbon nanofibers to steel fibers in the conductive composite fiber is 1:2.5, an ideal balance is achieved between the conductive network construction of the carbon nanofibers and the mechanical reinforcement of the steel fibers.

[0064] Examples 11-13 A dual-modal responsive fair-faced concrete differs from Example 6 in that it also includes 4-6 parts of fine expansion fibers.

[0065]

[0066] The fine expanded fibers in the table above are polyacrylamide-grafted polyaniline.

[0067] The concrete prepared in Examples 11-13 above was selected as the test object, and its crack self-healing rate, electrical conductivity, drying shrinkage, compressive strength and slump were tested respectively. The average value of the test results was recorded in the table below.

[0068]

[0069] As can be seen from Table 10, the fair-faced concrete in Examples 11-13 exhibits excellent performance in various aspects, with a slump of 148-165 mm, a 3-day compressive strength of 32.8-35.6 MPa, a 28-day compressive strength of 58.2-60.8 MPa, a crack self-healing rate of 91.8-95.5%, an electrical conductivity of 0.135-0.205 S / m, and a drying shrinkage of 235 × 10⁻⁶. -6 -255×10 -6 ; In Example 12, the best overall performance was achieved when 5 parts by weight of polyacrylamide-grafted polyaniline expanded fiber were added: the compressive strength at 3 days and 28 days reached 35.6 MPa and 60.8 MPa, respectively, and the drying shrinkage value was lower than that of Example 6 (375 × 10⁻⁶). -6 Significantly reduced to 235×10 -6 The electrical conductivity is 0.205 S / m, and the crack self-healing rate is 95.5%, which is a synchronous improvement compared to Example 6. This confirms that the fiber effectively enhances the conductive network while providing an expansion source, achieving a synergistic function of crack resistance and repair.

[0070] Examples 14-15 A dual-modal responsive fair-faced concrete differs from Example 11 in that the fine expansion fibers are sodium polyacrylate and hydrophilic polyurethane, respectively.

[0071]

[0072] The concrete prepared in Examples 14-15 above was selected as the test object, and its crack self-healing rate, electrical conductivity, drying shrinkage, compressive strength and slump were tested respectively. The average value of the test results was recorded in the table below.

[0073]

[0074] As shown in Table 12, the fair-faced concrete in Examples 14-15 has the following properties: slump of 160-162 mm, 3-day compressive strength of 33.5-34.8 MPa, 28-day compressive strength of 58.6-59.8 MPa, crack self-healing rate of 91.2-92.5%, electrical conductivity of 0.118-0.125 S / m, and drying shrinkage of 228 × 10⁻⁶. -6 -248×10 -6 ; Comparing the three expanded fibers, Example 11 (polyacrylamide grafted polyaniline) exhibited the best overall performance: its electrical conductivity (0.205 S / m) and self-healing rate (95.5%) were significantly higher than those of Examples 14 (0.125 S / m, 91.2%) and 15 (0.118 S / m, 92.5%), demonstrating that its conductive components effectively enhanced the repair network. In Example 14, the sodium polyacrylate exhibited a drying shrinkage resistance value of 228 × 10⁻⁶. -6 It exhibits the best shrinkage performance, but polyacrylamide-grafted polyaniline requires careful consideration to ensure crack resistance (dry shrinkage value is 235 × 10⁻⁶). -6 It also achieves multi-functional collaboration.

[0075] Examples 16-18 A dual-modal response fair-faced concrete differs from Example 1 in that it also includes 6-10 parts of WO3@aggregate.

[0076]

[0077] The concrete prepared in Examples 16-18 above was selected as the test object, and its crack self-healing rate, electrical conductivity, drying shrinkage, compressive strength and slump were tested respectively. The average value of the test results was recorded in the table below.

[0078]

[0079] Table 14 shows the following properties of Examples 16-18: slump 172-178 mm, 3-day compressive strength 29.2-30.1 MPa, 28-day compressive strength 53.6-54.8 MPa, crack self-healing rate 89.5-90.8%, electrical conductivity 0.035-0.038 S / m, and drying shrinkage 365 × 10⁻⁶ mm. -6 -372×10 -6 .

[0080] The addition of WO3 aggregate resulted in a stable improvement in concrete performance: the 28-day compressive strength increased from 52.3 MPa in Example 1 to 54.8 MPa in Example 18, the self-healing rate of cracks increased from 88.0% to 90.8%, and the drying shrinkage decreased from 380 × 10⁻⁶ MPa. -6 Reduced to 365×10 -6 This indicates that WO3@ aggregate effectively improves the interface structure as a functional aggregate, but its electrical conductivity is 0.035-0.038 S / m, which is lower than that of Example 1, proving that it mainly enhances performance through physical action rather than providing a conductive path.

[0081] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of this application, they are protected by patent law. A dual-modal response fair-faced concrete and its preparation and repair method.

Claims

1. A dual-modal responsive fair-faced concrete, characterized in that: Including the following parts by weight of raw materials: Cement: 280-320 parts; Water: 105-110 parts; Sand: 520-540 parts; Stone: 720-780 portions; Microcapsules: 3-5 servings; The microcapsules comprise the following components: 35%-45% silicate, 30%-35% acrylate, 1.5%-2.5% tungsten oxide, 1%-5% micro / nano particles, 4-8% polyaniline, 1%-3% ionic surfactant, with the balance being titanium dioxide.

2. The dual-modal response fair-faced concrete according to claim 1, characterized in that: It also includes 12-18 parts of conductive composite fiber; The conductive composite fiber is composed of carbon nanofibers and steel fibers in a weight ratio of 1:(2-3), wherein the aspect ratio of the carbon nanofibers is greater than or equal to 1000, and the aspect ratio of the steel fibers is greater than or equal to 20.

3. The dual-modal response fair-faced concrete according to claim 1, characterized in that: It also includes 4-6 parts of fine expanded fibers, wherein the fine expanded fibers are selected from any one of polyacrylamide-grafted polyaniline, sodium polyacrylate, and hydrophilic polyurethane.

4. The dual-modal response fair-faced concrete according to claim 3, characterized in that: The fine expanded fibers are polyacrylamide-grafted polyaniline.

5. The dual-modal response fair-faced concrete according to claim 1, characterized in that: It also includes 6-10 parts of WO3@aggregate.

6. A method for preparing dual-modal responsive fair-faced concrete according to any one of claims 1-5, characterized in that, Includes the following steps: (1) First, put sand, stone, cement and WO3@ aggregate into the mixer and mix them evenly; (2) After dry mixing evenly, add water and finely expanded fibers; (3) Finally, add microcapsules and conductive composite fibers.

7. A method for repairing dual-modal responsive fair-faced concrete as described in any one of claims 1-6, characterized in that: The concrete substrate is energized under the following conditions: current magnitude 0.5-1.5 mA / mm². 2 The repair of the crack can be completed in 0.5-2 hours.

8. A microcapsule, characterized in that: It consists of the following components: 35%-45% silicate, 30%-35% acrylate, 1.5%-2.5% tungsten oxide, 1%-5% micro / nano particles, 4-8% polyaniline, 1%-3% ionic surfactant, with the balance being titanium dioxide.

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