A high-strength and high-toughness concrete, its preparation method and toughness evaluation model

Abstract

The present invention discloses a high-strength and high-toughness concrete, which comprises the following components in parts by mass: 300-500 parts of fly ash, 300-500 parts of slag, 200-300 parts of silica fume, 100-200 parts of sodium hydroxide solution, 200-250 parts of sodium silicate solution, 300-400 parts of fine aggregate, 150-200 parts of water and prestressed fibers with a volume fraction of 0.5%-2.0%, wherein the prestressed fibers are prestressed fibers with a shape memory polymer cured on the surface. The present invention also provides a preparation method and a toughness evaluation model for the above high-strength and high-toughness concrete. The high-strength and high-toughness concrete provided by the present invention can effectively improve the reinforcement and toughening effects of the fibers.

Description

Technical Field

[0001] The present invention relates to the field of concrete materials, and particularly to a high-strength and high-toughness concrete, a preparation method thereof, and a toughness evaluation model. Background Art

[0002] At present, the building materials used in hydraulic structures are still mainly concrete. Traditional concrete has outstanding advantages such as wide material sources and high economy. However, when it is applied to infrastructure construction, there are many inherent defects, such as poor tensile performance, high brittleness, insufficient toughness, and difficult crack control. In a harsh service environment, the strength (compression, bending, shear) of structural load-bearing members is insufficient, especially the low toughness level and the failure of joint connections are the main reasons for the failure of hydraulic concrete structures and even the overall failure of the structure. Once a hydraulic structure fails, it will seriously threaten the normal use of hydraulic buildings, and in severe cases, it will cause incalculable losses and consequences. Therefore, it is necessary to develop high-performance concrete materials, optimize the strength and toughness levels of concrete in key parts of hydraulic structures that are prone to damage in harsh service environments, and improve the overall disaster prevention, mitigation, and resistance capabilities of hydraulic buildings.

[0003] In order to improve the inherent defects of traditional concrete and enhance its strength and toughness, researchers have adopted the method of incorporating short-cut fibers into the concrete matrix material to effectively exert the bridging effect of the fibers and develop high-performance concrete. In the process of the development of high-performance concrete, two types of concrete materials have received extensive attention. The first is engineered / strain-hardening cementitious composites (ECC) with polymer fibers as the main reinforcing material. This is a high-performance fiber-reinforced composite material designed based on micro-mechanics criteria, which can achieve significant strain hardening and multiple cracking behaviors under direct tensile action. Generally, the tensile strain capacity of ECC is reported to be 1% - 8% (i.e., 100 - 800 times that of ordinary concrete), but its compressive strength is usually below 60 MPa. The second is ultra-high-performance concrete (UHPC) with steel fibers as the main reinforcing material. Compared with ordinary ECC materials, UHPC has much higher strength (usually above 60 MPa), but its tensile strain capacity is relatively insufficient (usually below 1.0%), which severely limits its application scope in practical engineering. In recent years, in order to meet the increasing requirements of hydraulic structures such as ports, docks, and dams for the strength and toughness of concrete materials, the research on high-strength and high-toughness concrete has gradually become one of the main directions of the current development of concrete materials.

[0004] In the process of the development of high-performance concrete, fiber modification is the core. At the same time, in order to integrate the characteristics of different types of fibers (steel fibers, polymer fibers) in enhancing or toughening the concrete matrix material, the research on hybrid fiber concrete has received extensive attention. For example, in the invention patent CN109369095A, by giving full play to the performance characteristics of different types, a hybrid fiber concrete and its preparation method and application are proposed. However, due to the mismatch of physical and chemical properties, the interfacial compatibility between the fiber and the concrete is not good. If the interfacial compatibility is not good, it may lead to the weakening of the bonding performance between the fiber and the matrix, the fiber is easily pulled out from the matrix, the excellent tensile performance of the fiber itself cannot be fully exerted, and it is difficult to disperse the stress transmitted by the concrete matrix material, ultimately resulting in the decline of the performance of the concrete material. Therefore, improving the interfacial characteristics between the fiber and the concrete is the key to improving the strength and toughness of fiber concrete.

[0005] Therefore, it is necessary to optimize the interfacial action effect between the fiber and the concrete matrix in view of the deficiencies in the prior art, and then develop a high-strength and high-toughness concrete with both high strength and high toughness characteristics, and establish a corresponding bending toughness evaluation method. Summary of the Invention

[0006] Object of the Invention: In order to solve the problem that in the existing preparation process of hybrid fiber concrete, the interfacial compatibility between the fiber and the concrete matrix material is not good, resulting in insufficient strengthening and toughening effects, the present invention provides a high-strength and high-toughness concrete and its preparation method and toughness evaluation model.

[0007] In order to solve the above technical problems, on the one hand, the present invention provides a high-strength and high-toughness concrete, which comprises the following components in parts by mass: 300-500 parts of fly ash, 300-500 parts of slag, 200-300 parts of silica fume, 100-200 parts of sodium hydroxide solution, 200-250 parts of sodium silicate solution, 300-400 parts of fine aggregate, 150-200 parts of water and prestressed fibers with a volume fraction of 0.5%-2.0%, wherein the prestressed fibers are fibers with a shape memory polymer cured on the surface.

[0008] Specifically, the prestressed fibers are prepared through the following steps:

[0009] A1: Dissolve the shape memory polymer in cyclohexane at a mass ratio of 10%-15%, mix well to obtain a shape memory polymer solution;

[0010] A2. Treat the fiber surface with anhydrous ethanol and plasma in sequence; specifically, use anhydrous ethanol to clean the fiber in an ultrasonic cleaner for 10 - 15 minutes to remove surface grease, dust and other impurities. After that, in order to improve the adhesion of the coating, the fiber surface will be treated with plasma, and this step enhances the bonding effect of the coating by changing the surface energy;

[0011] A3. Use a spraying device to spray the fiber with a shape - memory polymer solution, with the coating thickness being 50 - 100 μm, and then cure it to obtain the fiber with a cured coating;

[0012] A4. Perform shape - memory programming on the fiber with a cured coating. After the shape - memory programming is completed, the fiber naturally cools to room temperature without removing the tensile force to form prestressed fiber.

[0013] Shape - memory polymers (abbreviated as SMP) have attracted much attention in the field of materials science due to their unique shape - memory effect. When subjected to external stimuli (such as temperature changes), SMP can transform from one form to another preset form. Utilizing this property, prestress can be introduced into concrete materials to cope with complex loading conditions and environmental changes.

[0014] When performing the coating preparation step of SMP, the key is to select a suitable SMP material. For this application, we have selected polyurethane - based SMP, which is particularly suitable for temperature - activated applications due to its excellent shape - memory properties and thermal stability. Polyurethane - based SMP is soft and plastic at ambient temperature, while when heated to its transition temperature (about 55°C), it can quickly harden and remember the new shape.

[0015] During the coating preparation process, preferably dissolve the polyurethane - based SMP in cyclohexane at a mass ratio of 15% to form a homogeneous solution. The viscosity of this solution is adjusted to be suitable for spraying, and usually the viscosity range should be controlled between 1000 and 1200 cP. To ensure the uniformity and functionality of the coating, use a professional spraying device for operation. The spraying pressure is set to about 2 - 3 bar, and the nozzle diameter is 0.5 mm, so as to form a uniform coating with a thickness of 50 - 100 μm on the fiber surface. In addition, ensure that the working environment is dust - free to avoid impurities on the coating surface.

[0016] The treatment of the fiber and the application of the coating are key steps to achieve good interfacial bonding. First, the fiber needs to be thoroughly cleaned to remove surface grease, dust and other impurities, usually by treating it with anhydrous ethanol in an ultrasonic cleaner for 15 minutes. After that, in order to improve the adhesion of the coating, the fiber surface will be treated with plasma, and this step enhances the bonding effect of the SMP coating by changing the surface energy.

[0017] The coating is applied using spraying technology because spraying can cover the fiber surface more evenly, ensuring the consistency of the coating. During the spraying process, the thickness and uniformity of the coating are key control points to ensure that each fiber is completely and evenly covered.

[0018] Among them, the fiber composite includes steel fibers and polymer fibers. The addition ratio of the fiber composite is generally about 0.5%-2.0% of the total volume of the concrete. Preferably, the addition ratio is 2%, and the ratio of steel fibers to polymer fibers is preferably 1:1 to 1:3.

[0019] In step A3, the curing conditions are as follows: The coated fibers are cured at 60-70°C for 2-3 hours. Preferably, the coated fibers need to be cured at 60°C for 2 hours. This step aims to ensure that the SMP material is completely cured and forms strengthened chemical bonds with the fiber surface.

[0020] In step A4, the steps of shape memory programming are as follows: The fibers with the cured coating are placed in a temperature-controlled oven, the temperature is set at 100-120°C. At this temperature, the fibers are mechanically stretched, the strain rate is controlled at 2-3%, and this state is maintained for 30-50 minutes.

[0021] Heat treatment and shape memory programming are the core links to achieve the shape memory effect. Preferably, during the programming stage, the coated fibers are placed in a temperature-controlled oven, the temperature is set at 100°C, which is higher than the shape fixing temperature of the SMP. At this temperature, the fibers are mechanically stretched, the strain rate is controlled at 3%, and this state is maintained for 30 minutes. During this process, the SMP material will change from the temporary form to the fixed stretched state.

[0022] After programming, the fibers are naturally cooled to room temperature without removing the tensile force. This step is crucial because it ensures that the fibers do not retract during cooling and curing, thus retaining the applied prestress. This prestress will be activated by the triggering temperature (40-60°C) in future applications to achieve the shape memory recovery of the fibers, thereby introducing prestress into the concrete.

[0023] Among them, the average particle size of the fly ash is 8-10 μm; the average particle size of the slag is 8-10 μm; the average particle size of the silica fume is 1-5 μm, and the average particle size of the fine aggregate is 0.5-1.0 mm.

[0024] The concentration of the sodium hydroxide solution is 12-16 M.

[0025] The present invention further provides a method for preparing the above-mentioned high-strength and high-toughness concrete, including the following steps:

[0026] B1. Weigh 300 - 500 parts by mass of fly ash, 300 - 500 parts of slag, 200 - 300 parts of silica fume, and 300 - 400 parts of fine aggregate components and put them into a mixing device for dry mixing for 120 - 180 s;

[0027] B2. Weigh 100 - 200 parts by mass of sodium hydroxide solution, 200 - 250 parts of sodium silicate solution and 150 - 200 parts of water, pour them into the mixing device at one time, and conduct wet mixing for 150 - 300 s;

[0028] B3. Put fibers with shape - memory polymers surface - cured with a volume fraction of 0.5% - 2% into the mixing device for dry mixing for 120 - 180 s to make the fiber composite evenly distributed to obtain concrete. Finally, pour the evenly - stirred fresh mixture into a mold and vibrate it to make it dense;

[0029] B4. After standing and curing at room temperature for 20 - 26 hours, demold the specimen, and then transfer it to a standard curing room (control the temperature at 17 - 23 °C and the relative humidity at 90% - 95%) for curing until the test age.

[0030] When mixing concrete, add the treated fibers evenly to the concrete. The addition ratio of the fibers is generally about 2% of the total volume of the concrete. Use efficient mixing equipment to ensure that the fibers are evenly distributed in the concrete and avoid agglomeration. The even distribution of the fibers is crucial for achieving the mechanical properties of the overall structure and can effectively enhance the strength and toughness of the concrete.

[0031] Concrete pouring is the last step to realize the formation of the structure. After the concrete pouring is completed, immediately carry out curing to prevent cracks caused by premature drying. During the curing process, pay special attention to controlling the temperature and humidity conditions (control the temperature at 17 - 23 °C and the relative humidity at 90% - 95%). The hydration heat of the concrete will trigger the shape - memory effect of the SMP, and at this time, the internal temperature of the concrete will rise to 50 °C to 70 °C. Maintain appropriate curing temperature and humidity to ensure that the concrete hardens slowly and evenly, and at the same time activate the prestress in the SMP fibers.

[0032] This series of steps constitutes a complete solution for applying the shape - memory polymer coating technology to concrete fibers. From the selection and preparation of materials to the final application and performance verification, each link is aimed at ultimately achieving the goal of improving the crack - resistance performance and durability of the concrete structure.

[0033] This application further proposes a method for calculating the flexural toughness of the above - mentioned high - strength and high - toughness concrete, including the following steps:

[0034] Step 1: Select the concrete component to be tested, conduct a four - point bending test, and draw the load - mid - span deflection test curve of the concrete component to be tested;

[0035] Step 2: According to the load and mid-span deflection test curve of the concrete component to be measured, obtain the load value P corresponding to the proportional limit point of the concrete component on this test curve LOP and the mid-span deflection value 𝛿 LOP ; at the same time, obtain the load value P corresponding to the fracture modulus point of the concrete component on this test curve MOR and the mid-span deflection value 𝛿 MOR ;

[0036] Step 3: According to the length L a , width b, height h, and net span L 0 of the concrete component to be measured, the proportional limit load P LOP , proportional limit deflection 𝛿 LOP , fracture modulus load P MOR , fracture modulus deflection 𝛿 MOR , use formulas (1)-(7) to establish a calculation method for the flexural toughness of concrete that includes the strain-hardening flexural strength ratio R hm and the strain-hardening flexural energy Q m :

[0037] Strain-hardening flexural strength ratio (1)

[0038] Strain-hardening flexural energy (2)

[0039] Equivalent fracture modulus strength (3)

[0040] Equivalent proportional limit strength (4)

[0041] Equivalent fracture modulus energy (5)

[0042] Equivalent proportional limit energy (6)

[0043] Pure flexural cross-sectional volume (7)

[0044] The present invention also proposes the application of the above-mentioned high-strength and high-toughness concrete in the key vulnerable parts of water discharge buildings.

[0045] Beneficial effects: A high-strength and high-toughness concrete provided by the present invention can effectively improve the strengthening and toughening effects of fibers. Description of the drawings

[0046] Figure 1 It is the load-deflection curve of Example 1. Detailed implementation manners

[0047] The following further specifically describes the present invention in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0048] In the following embodiments, fly ash, slag and silica fume are all purchased from Henan Borun Foundry Materials Co., Ltd. The average particle size of fly ash is 8-10 μm, and its main chemical components include 30%-40% of Al 2 O 3 , 45%-55% of SiO 2 , 1%-5% of CaO; the average particle size of slag is 8-10 μm, and its main chemical components include 10%-20% of Al 2 O 3 , 30%-40% of SiO 2 , 30%-40% of CaO; the sodium hydroxide solution is made of sodium hydroxide flake powder with a purity of 98.5% and a concentration of 14 M; the sodium silicate solution mainly consists of 8.35% of Na 2 O, 26.54% of SiO 2 and 65.11% of H 2 O; the average particle size of silica fume is 1-5 μm, and its main chemical components include 95%-98% of SiO 2 ; the maximum particle size of the fine aggregate is 1 mm, and the average particle size is 0.645 mm; the hybrid fiber is composed of steel fiber and polymer fiber, and the volume fractions of the two in the total raw materials are 0.5%-2.0%.

[0049] Example 1

[0050] A high-strength and high-toughness concrete is prepared through the following steps:

[0051] (1) Preparation of prestressed fibers:

[0052] The fibers used in this application include steel fibers and polymer fibers. Among them, the steel fibers are copper-plated steel fibers produced by Hebei Biaocai Rubber Products Co., Ltd., with a length of 13 mm, a diameter of 0.20 mm, a density of 7.80 g / cm 3 , a tensile strength of 2930 MPa, and an elastic modulus of 210 GPa; the polymer fibers are PE fibers produced by Hubei Jiateng Textile Co., Ltd., with a length of 13 mm, a diameter of 0.025 mm, a density of 0.97 g / cm 3 , a tensile strength of 3100 MPa, and an elastic modulus of 122 GPa.

[0053] The above two kinds of fibers are respectively prepared into prestressed steel fibers and prestressed polymer fibers through the following steps:

[0054] A1. Dissolve the polyurethane-based shape memory polymer (SMP) in cyclohexane at a mass ratio of 15% to form a homogeneous solution;

[0055] A2. Clean the fibers in an ultrasonic cleaner with absolute ethanol for 15 minutes to remove surface grease, dust, and other impurities. After that, to improve the adhesion of the SMP coating, the fiber surface will be treated with plasma, which enhances the bonding effect of the SMP coating by changing the surface energy;

[0056] A3. Spray the fibers using spraying equipment to attach the SMP coating to the fiber surface. The spraying pressure is set to about 2 - 3 bar, and the nozzle diameter is 0.5 mm, so as to form a uniform coating with a thickness of 50 - 100 μm on the fiber surface. The fibers with the additional coating need to be cured at 60°C for 2 hours to ensure that the SMP material is completely cured and forms strengthened chemical bonds with the fiber surface;

[0057] A4. Place the fibers with the cured coating in a temperature-controlled oven, with the temperature set at 100°C, which is higher than the shape fixation temperature of the SMP. At this temperature, the fibers are mechanically stretched, with the strain rate controlled at 2 - 3%, and this state is maintained for 30 minutes. During this process, the SMP material will change from its temporary form to a fixed stretched state.

[0058] A5. After the shape memory programming is completed, the fibers are naturally cooled to room temperature without removing the tensile force. The fibers will not retract during the cooling and curing process, thus retaining the applied prestress and forming prestressed fibers.

[0059] (2) Preparation method of high-strength and high-toughness concrete.

[0060] By mass, take 520 parts of fly ash, 520 parts of slag, 260 parts of silica fume, 390 parts of fine aggregate, and dry mix for 150 s; then, by mass, add 156 parts of sodium hydroxide solution, 234 parts of sodium silicate solution, and 182 parts of water, and wet mix for 300 s. Finally, add prestressed fibers with a volume fraction of 2.0% (composed of 0.5% prestressed steel fibers and 1.5% prestressed polymer fibers) and dry mix for 150 s to make the fiber composite evenly distributed to obtain the concrete. Finally, pour the uniformly mixed fresh mixture into a mold, vibrate it to make it dense, and leave it to cure at room temperature for 20 - 26 hours, then demold the specimen, and then transfer it to a standard curing room (control the temperature at 17 - 23°C and the relative humidity at 90% - 95%) for curing until the test age.

[0061] Example 2

[0062] The basic formulation and preparation process are the same as those in Example 1, except that the mixing ratio of the prestressed fibers with a volume fraction of 2.0% added at the end is different (composed of 1.0% prestressed steel fibers and 1.0% prestressed polymer fibers).

[0063] Comparative Example 1

[0064] The basic formulation and preparation process are the same as those in Example 1, except that the mixing ratio of the prestressed fibers with a volume fraction of 2.0% added at the end is different (composed only of 2.0% prestressed polymer fibers).

[0065] Comparative Example 2

[0066] The basic formulation and preparation process are the same as those in Example 1, except that the mixing ratio of the prestressed fibers with a volume fraction of 2.0% added at the end is different (composed of 1.5% prestressed steel fibers and 0.5% prestressed polymer fibers).

[0067] Comparative Example 3

[0068] The basic formulation and preparation process are the same as those in Example 1, except that the mixing ratio of the prestressed fibers with a volume fraction of 2.0% added at the end is different (composed only of 2.0% prestressed steel fibers).

[0069] Comparative Example 4

[0070] The basic formulation and preparation process are the same as those in Example 1, except that the same amount of hybrid fibers added do not have a prestressed coating, that is, 0.5% steel fibers and 1.5% polymer fibers are directly added.

[0071] Comparative Example 5

[0072] The basic formulation and preparation process are the same as those in Example 1, except that no fibers are added to the matrix, that is, it is a pure matrix material.

[0073] The properties of the concrete specimens obtained from the examples and comparative examples after standard curing were tested:

[0074] (1) For the cube specimens with dimensions of 50×50×50 mm 3 uniaxial compression performance tests were carried out to determine the compressive strength of the specimens in each example and comparative example. It was carried out in accordance with the "Standard for Test Methods of Physical and Mechanical Properties of Concrete GB / T50081 - 2019", and a 3000 kN microcomputer-controlled pressure testing machine produced by Shanghai Hualong Testing Instruments Co., Ltd. was used for determination. According to the test specifications, the loading speed was 0.5 MPa / s, and the test results are shown in Table 1.

[0075] (2) For specimens with dimensions of 400×100×15 mm 3For thin plate specimens, a four-point bending performance test was carried out to determine the bending performance of the specimens in each example and comparative example. It was carried out in accordance with the "Standard for Test Methods of Physical and Mechanical Properties of Concrete GB / T 50081-2019", and a 2000 kN electro-hydraulic servo universal testing machine produced by Shanghai Hualong Testing Instrument Co., Ltd. was used for determination. According to the test specifications, the loading speed was 0.5 mm / min, and the calculation results of relevant characteristic parameters are shown in Table 2-4.

[0076] Among them, the calculation method of the flexural toughness of concrete is as follows:

[0077] Step 1: Select the concrete component to be tested, conduct a four-point bending test, and draw the load and mid-span deflection test curve of the concrete component to be tested;

[0078] Step 2: According to the load and mid-span deflection test curve of the concrete component to be tested, obtain the load value P corresponding to the proportional limit point of the concrete component on the test curve LOP and the mid-span deflection value 𝛿 LOP ; at the same time, obtain the load value P corresponding to the fracture modulus point of the concrete component on the test curve MOR and the mid-span deflection value 𝛿 MOR .

[0079] Step 3: According to the length L a , width b, height h, and net span L 0 of the concrete component to be tested, the proportional limit load P LOP , proportional limit deflection 𝛿 LOP , fracture modulus load P MOR , fracture modulus deflection 𝛿 MOR , establish a calculation method for the flexural toughness of concrete including the strain-hardening flexural strength ratio R hm and the strain-hardening flexural energy Q m .

[0080] The calculation method of the flexural toughness of the concrete is as follows:

[0081] Strain-hardening flexural strength ratio (1)

[0082] Strain-hardening flexural energy (2)

[0083] Equivalent fracture modulus strength (3)

[0084] Equivalent proportional limit strength (4)

[0085] Equivalent fracture modulus energy (5)

[0086] Equivalent proportional limit energy (6)

[0087] Pure flexural cross-sectional volume (7)

[0088] Table 1 Compressive strength test results of examples and comparative examples

[0089]

[0090] Table 2 Characteristic parameters of load-deflection curves of examples and comparative examples

[0091]

[0092] Table 3 Calculation results of bending characteristic parameters of examples and comparative examples

[0093]

[0094] Table 4 Calculation results of flexural toughness parameters of examples and comparative examples

[0095]

[0096] Based on the above characteristic parameters, it can be seen that by applying a high-strength and high-toughness concrete provided by the present invention, the strengthening and toughening effects of fibers can be effectively improved, and the calculated values of the flexural toughness characteristic parameters of the examples are better than those of the comparative examples.

[0097] The present invention provides an idea and method for high-strength and high-toughness concrete. There are many specific methods and ways to implement this technical solution. The above description is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by existing technologies.

Claims

1. A high-strength and high-toughness concrete, characterized in that: The invention comprises the following components in parts by mass: 300-500 parts of fly ash, 300-500 parts of slag, 200-300 parts of silica fume, 100-200 parts of sodium hydroxide solution, 200-250 parts of sodium silicate solution, 300-400 parts of fine aggregate, 150-200 parts of water and prestressed fiber with a volume fraction of 0.5%-2.0%, wherein the prestressed fiber is a fiber composite with a shape memory polymer cured on the surface, and the shape memory polymer is a polyurethane-based shape memory polymer or a copolyamide-based shape memory polymer.

2. The high-strength and high-toughness concrete according to claim 1, characterized in that: The prestressed fiber is prepared by the following steps: A1: dissolving the shape memory polymer in cyclohexane at a mass ratio of 10%-15%, and mixing well to obtain a shape memory polymer solution; A2, treating the fiber surface with anhydrous ethanol and plasma in turn; A3, spraying the fiber with a shape memory polymer solution using a spraying device, with a coating thickness of 50-100 μm, and then curing to obtain a fiber with a cured coating; A4. The fiber with the cured coating is subjected to shape memory programming. After the shape memory programming is completed, the fiber is naturally cooled to room temperature without removing the tensile force to form a prestressed fiber.

3. The high-strength and high-toughness concrete according to claim 2, characterized in that: In A2, the fibers include steel fibers and polymer fibers.

4. The high-strength and high-toughness concrete according to claim 2, characterized in that: In step A3, the curing conditions are: curing the coated fiber at 60-70° C. for 2-3 hours.

5. The high-strength and high-toughness concrete according to claim 2, characterized in that: In step A4, the shape memory programming step is as follows: the fiber with the cured coating is placed in a temperature-controlled oven, the temperature is set to 100-120°C, at which temperature, the fiber is mechanically stretched, the strain rate is controlled at 2-3%, and this state is maintained for 30-50 minutes.

6. The high-strength and high-toughness concrete according to claim 1, characterized in that: The average particle size of the fly ash is 8-10 μm; the average particle size of the slag is 8-10 μm; the average particle size of the silica fume is 1-5 μm; the average particle size of the fine aggregate is 0.5-1.0 mm; and the concentration of the sodium hydroxide solution is 12-16 M.

7. The method for preparing the high-strength and high-toughness concrete according to any one of claims 1 to 6, characterized in that: The steps include: B1. Weigh 300-500 parts of fly ash, 300-500 parts of slag, 200-300 parts of silica fume and 300-400 parts of fine aggregate components by mass, put them into a mixing device and dry mix for 120-180 seconds; B2. Weigh 100-200 parts of sodium hydroxide solution, 200-250 parts of sodium silicate solution and 150-200 parts of water by mass, pour them into a stirring device at one time, and wet mix for 150-300 s; B3, putting 0.5%-2% by volume of fibers with a shape memory polymer cured on the surface into a stirring device for dry mixing for 120-180 s to evenly distribute the fibers to obtain concrete, and finally pouring the evenly mixed new mixture into a mold and compacting it by vibration; B4. After standing and curing at room temperature for 20-26 hours, the specimen is demoulded and then transferred to a standard curing room for curing until the test age.

8. The preparation method according to claim 7, characterized in that: The curing conditions are: control the temperature at 17-23℃ and the relative humidity at 90%-95%.

9. The method for calculating the bending toughness of high-strength and high-toughness concrete according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: Select the concrete component to be tested, conduct a four-point bending test, and draw the load and mid-span deflection test curve of the concrete component to be tested; Step 2: According to the load and mid-span deflection test curve of the concrete member to be tested, obtain the load value P corresponding to the proportional limit point of the concrete member on the test curve. LOP and the mid-span deflection 𝛿 LOP ; At the same time, the load value P corresponding to the rupture modulus point of the concrete component on the test curve is obtained MOR and the mid-span deflection 𝛿 MOR ; Step 3: According to the length L of the concrete component to be tested a , width b, height h, clear span L0, proportional limit load P LOP , proportional limit deflection 𝛿 LOP , rupture modulus load P MOR , modulus of rupture deflection 𝛿 MOR , using formulas (1)-(7) to establish the strain hardening bending strength ratio R hm and strain hardening bending energy Q m Calculation method of concrete flexural toughness: Strain hardening flexural strength ratio (1) Strain hardening bending energy (2) Equivalent rupture modulus strength (3) Equivalent proportional ultimate strength (4) Equivalent rupture modulus (5) Equivalent proportional limit energy (6) Pure bending section volume (7).

10. Use of the high-strength and high-toughness concrete according to any one of claims 1 to 6 in key parts of drainage structures that are easily damaged.

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