Cold region hydraulic self-repairing concrete based on geopolymer and preparation method thereof

Abstract

The invention discloses a geopolymer-based cold region hydraulic self-repairing concrete and a preparation method thereof, and belongs to the technical field of self-repairing concrete. The concrete is prepared from an excessive composite precursor, a composite alkali activator, calcium fluoride, polyvinyl alcohol, retired fan blade fibers, aggregate and water according to a specific ratio, wherein the excessive composite precursor is prepared from slag powder, retired fan blade micro powder, fly ash and nano silicon dioxide. The preparation method comprises the steps of premixed material preparation, slurry preparation, pouring molding, surface spraying and 7-14-day watering maintenance. The strength recovery rate of the concrete exceeds 100%, the number of anti-freezing cycles reaches 350-400, the mechanical property is excellent, solid waste resource utilization can be achieved, environmental protection and energy saving are achieved, and the concrete is suitable for hydraulic structures such as underground tunnels in cold regions and water level change regions. The technical problems that existing hydraulic concrete in the cold region is poor in freezing resistance, free of self-repairing capacity, insufficient in environmental friendliness and the like are solved.

Description

Technical Field

[0001] This invention belongs to the field of self-healing concrete technology, specifically relating to a geopolymer-based self-healing hydraulic concrete for cold regions and its preparation method. Background Technology

[0002] Concrete is the most widely used building material in hydraulic engineering construction. However, hydraulic concrete structures operating in cold regions (such as northern my country and high-altitude areas) are subjected to the combined effects of extremely harsh environments, including extreme diurnal temperature variations, frequent freeze-thaw cycles, strong ultraviolet radiation, and water erosion. These complex and severe conditions easily lead to the formation of micro-cracks within the concrete structure, which then propagate and connect, eventually causing cracking, erosion, and a sharp decline in strength and durability. This severely shortens the lifespan of the project, threatens flood control safety, and makes subsequent repair and reinforcement difficult and costly.

[0003] To address these challenges, self-healing concrete has become a research hotspot. Self-healing concrete can automatically repair cracks and restore some or all of its properties when micro-damage occurs, through internal or external mechanisms. Currently, mainstream self-healing technologies mainly rely on internal capsules, microbial mineralization, or shape memory alloys, but these methods often suffer from problems such as difficulty in encapsulating repair agents, high costs, poor compatibility with concrete, limited repair efficiency, or only being able to repair once.

[0004] On the other hand, the traditional silicate cement production process is energy-intensive and generates large carbon emissions, which contradicts the requirements of environmental sustainability. Geopolymers are inorganic polymer cementitious materials polymerized from aluminosilicate raw materials under alkaline conditions. They possess advantages such as high early strength, high temperature resistance, corrosion resistance, low permeability, and environmental friendliness (they can utilize industrial solid waste), and are considered a potential alternative to silicate cement. However, ordinary geopolymer concrete still has shortcomings in terms of frost resistance and toughness, and does not yet possess active self-healing capabilities.

[0005] Therefore, there is an urgent need to develop a new type of hydraulic concrete material for cold regions that comprehensively utilizes solid waste, is environmentally friendly, and possesses excellent frost resistance, wear resistance, and efficient self-healing capabilities. Summary of the Invention

[0006] To address the technical problems of existing cold-region hydraulic concrete, such as poor frost resistance, lack of self-healing ability, insufficient environmental friendliness, and the difficulty of adapting existing geopolymer concrete to the extreme environment of cold-region hydraulic structures, the primary objective of this invention is to provide a geopolymer-based self-healing concrete for cold-region hydraulic structures. This concrete uses industrial solid waste as the main raw material and possesses excellent frost resistance, abrasion resistance, and significant self-healing ability, which can effectively extend the service life of hydraulic structures in cold regions.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned self-healing concrete, which is simple in process, easy to implement, and can ensure that the concrete obtains the aforementioned excellent properties.

[0008] Technical solution To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a geopolymer-based self-healing hydraulic concrete for cold regions, characterized in that the main material is composed of the following raw materials in parts by weight: 325-365 parts of slag powder 65-90 parts of decommissioned wind turbine blade powder 33-52 parts fly ash 8-13 parts of nano-silica 48-55 parts of fast-dissolving potassium silicate 20 parts of anhydrous sodium metasilicate Sodium metasilicate pentahydrate 12-17 parts, 1-2 parts of fiber from retired wind turbine blades 1-3 parts calcium fluoride 3-9 parts of polyvinyl alcohol, 850-905 parts of manufactured sand 696-740 pieces of crushed stone 180-200 parts water.

[0009] The slag powder, decommissioned wind turbine blade powder, fly ash, and nano-silica together constitute the composite precursor. One of the core concepts of this invention is that the total amount of this composite precursor is designed to be "excessive," specifically 1.3 times the amount of a conventional precursor, while the dosage of the composite alkali activator, composed of readily soluble potassium silicate and sodium metasilicate pentahydrate, remains unchanged. This combination of "excessive precursor and constant activator" aims to ensure that after the initial curing of the geopolymer, some unreacted active precursor particles remain inside the concrete.

[0010] Furthermore, after the concrete has been poured, shaped, and initially cured, a solution prepared from anhydrous sodium metasilicate in a specified amount is sprayed onto its surface. Part of this solution penetrates the surface layer, while some of the anhydrous sodium metasilicate remains in the surface pores in crystalline form. This constitutes another key aspect of the self-healing function of this invention: providing an additional alkaline activation source for subsequent repair reactions.

[0011] When microcracks develop in concrete under complex cold environments, external moisture penetrates along the cracks. This moisture dissolves anhydrous sodium metasilicate crystals remaining near and on the surface of the cracks, forming a highly alkaline solution. This alkaline solution comes into contact with excess unreacted precursor particles pre-existing within the concrete, triggering secondary or even multiple alkali-activated reactions to generate new geopolymer gels. This gel fills and bonds the microcracks, achieving automatic repair and reinforcement.

[0012] As a preferred option, the specific technical parameters of each raw material are as follows: The slag powder is of grade S95 with a specific surface area of ​​not less than 400 m² / kg to ensure its high activity.

[0013] The decommissioned wind turbine blade powder is obtained by grinding and screening decommissioned wind turbine blades (usually glass fiber reinforced composite materials) with a fineness of 200 mesh. It not only exerts an active effect but also realizes the high-value utilization of solid waste.

[0014] The decommissioned wind turbine blade fibers are short-cut fibers extracted from decommissioned blades, with a single filament diameter of about 5 μm and a length of 3 to 5 mm, which serve to toughen and prevent cracking.

[0015] The fly ash is either Grade I or Grade II.

[0016] The nano-silica is a white powder with a particle size of 5–100 nm, used to fill micropores and improve density and early strength.

[0017] The readily soluble potassium silicate is a white powder with a modulus of 2.3–2.5; the anhydrous sodium metasilicate is an industrial-grade white powder with a density of approximately 2.4 g / cm³; and the pentahydrate sodium metasilicate is an industrial-grade white powder with a fineness of 60 mesh. The combined use of readily soluble potassium silicate and pentahydrate sodium metasilicate can effectively suppress the common surface "frost" phenomenon in geopolymers.

[0018] The calcium fluoride is a white powder with a fineness of 100 mesh and a loss on ignition of ≤0.6%. It can participate in the reaction to form a dense fluoride phase, promoting self-repair.

[0019] The polyvinyl alcohol is a dry powder mixture with a fineness of 160 mesh. It serves as a polymer modifier to improve the workability of the mixture and enhance its impermeability and freeze resistance.

[0020] The fineness modulus of the manufactured sand is 2.4 to 2.8; the particle size of the crushed stone is 5 to 20 mm, and it is continuously graded.

[0021] Secondly, the present invention provides a method for preparing the above-mentioned geopolymer-based self-healing hydraulic concrete for cold regions, characterized by comprising the following steps: Step S1: Preparation of premixed dry materials: Weigh out slag powder, decommissioned fan blade powder, fly ash, nano silica, decommissioned fan blade fiber, calcium fluoride, polyvinyl alcohol, manufactured sand and crushed stone according to the proportion, put them into a forced mixer, dry mix for 2 minutes, and mix evenly to obtain a dry material mixture.

[0022] Step S2: Prepare and mix the slurry: Dissolve the readily soluble potassium silicate and sodium metasilicate pentahydrate in all the water according to the specified ratio, and stir until fully dissolved to obtain an alkali activator solution. Pour this solution into the dry mixture from step S1, and wet mix for 3 minutes using a forced mixer until a homogeneous concrete mixture is formed.

[0023] Step S3, Casting and Shaping: The mixture should be poured into the formwork promptly, and thoroughly compacted using an immersion vibrator. Compaction should continue until the concrete surface no longer shows significant settling, no air bubbles appear, and slurry appears on the surface. Adding water is strictly prohibited during the casting process.

[0024] Step S4, Surface Spraying Treatment: 12 hours after pouring and molding (when the concrete has initially hardened), dissolve all the anhydrous sodium metasilicate in the formula in 100 parts water to prepare a solution. Use a spraying device to evenly spray this solution onto the concrete surface. Spraying is done in multiple applications, usually after the previous layer of surface solution has been absorbed or the surface has slightly dried (approximately 1 hour) before the next application, for a total of 3 applications.

[0025] Step S5, Curing: After the surface spraying treatment is completed, water curing should be started immediately to keep the concrete surface continuously moist. It is recommended that the ambient temperature for curing should not be lower than 5℃, and the curing time is 7 to 14 days.

[0026] Beneficial effects Compared with the prior art, the present invention has the following significant advantages: 1. Excellent self-healing ability: Through a formulation design of "excessive precursor and constant activator," combined with the subsequent surface spraying of anhydrous sodium metasilicate solution, a "repair agent reservoir" and "triggering mechanism" are built into the concrete. When microcracks occur and moisture penetrates, multiple alkali-activated reactions can be automatically triggered, achieving efficient crack repair. Tests show that after 14 days of curing, the compressive strength recovery rate of damaged concrete can reach over 106%, and the internal density (characterized by ultrasonic wave velocity) also basically recovers to the pre-damage level.

[0027] 2. Superior durability: The synergistic effect of nano-silica and calcium fluoride significantly improves the density of the geopolymer matrix; the toughening effect of the fibers in the decommissioned wind turbine blades inhibits the initiation and propagation of cracks; and the composite alkali activator formulation reduces frost formation. These combined effects give the concrete extremely high frost resistance (significantly increased number of frost cycles) and impact and abrasion resistance.

[0028] 3. Green environmental protection and resource utilization: Using industrial solid waste such as slag, fly ash, decommissioned wind turbine blade powder and fiber as the main raw materials, it completely replaces traditional silicate cement, significantly reducing production energy consumption and carbon dioxide emissions.

[0029] 4. The method is simple and practical: the preparation process is well integrated with traditional concrete construction, the surface spraying treatment is easy to operate, and there is no need for complicated equipment or expensive repair agent encapsulation technology, making it easy to promote and apply in engineering practice.

[0030] 5. Wide adaptability: The improved overall performance of the concrete in this invention, especially the combination of self-healing and high frost resistance, makes it very suitable for hydraulic structures in cold regions that are difficult to maintain and have harsh environments, such as underground tunnels, dam water level change zones, and canal linings, and has broad application prospects. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating the process of preparing and repairing self-healing concrete according to the present invention.

[0032] Figure 2 This is a schematic diagram showing the compressive strength relationship of concrete specimens in the examples and comparative examples before and after failure (loaded to 70% ultimate load) and after 14 days of repair and curing.

[0033] Figure 3 The graphs show the compressive strength recovery rate of concrete specimens in the examples and comparative examples after 14 days of curing following failure. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. The following embodiments and comparative examples are used to illustrate the present invention. The amount of composite precursor in the embodiments is 1.3 times that in the comparative examples, and the amount of base activator in the comparative examples is 18% of the amount of precursor. The mass of base activator in the embodiments and the comparative examples is the same. Example 1

[0035] 325 parts of slag powder, 65 parts of decommissioned wind turbine blade powder, 33 parts of fly ash, 8 parts of nano-silica, 1 part of decommissioned wind turbine blade fiber, 1 part of calcium fluoride, 3 parts of polyvinyl alcohol, 905 parts of manufactured sand, and 740 parts of crushed stone were placed in a mixer and forcibly stirred for 2 minutes. Then, 48 parts of readily soluble potassium silicate and 12 parts of sodium metasilicate pentahydrate were dissolved in 180 parts of water and added to the mixer, and forcibly stirred for 3 minutes to prepare two sets of compressive strength test specimens (100×100×100mm) and two sets of frost resistance test specimens (100×100×400mm). After 12 hours of casting, 20 parts of anhydrous sodium metasilicate were dissolved in 100 parts of water to prepare a solution, which was sprayed onto the surface of the cured geopolymer concrete specimens. One hour later, when the surface was dry, another layer was sprayed, for a total of three sprays. If the surface was not dry, the spraying time could be appropriately extended. After 24 hours, the mold was removed and the product was placed in a standard curing room. After 28 days of curing, a self-healing test and a freeze-resistance test were conducted.

[0036] Concrete self-healing test: One group of specimens was subjected to compressive strength test to obtain its average ultimate strength σ. max The other group first performed ultrasonic testing on each block to obtain the sound velocity value, and then loaded each block onto the machine to 70% σ. max The pressure was maintained for 60 seconds to create artificial cracks, and then each specimen was subjected to ultrasonic testing to obtain the sound velocity value after failure. After curing the specimens in a curing room for 14 days, they were taken out and ultrasonically tested again to obtain the sound velocity value after re-curing. Then, the ultimate strength test was performed, and finally, the strength recovery rate was calculated. Example 2

[0037] 345 parts of slag powder, 78 parts of decommissioned wind turbine blade powder, 40 parts of fly ash, 10 parts of nano-silica, 1 part of decommissioned wind turbine blade fiber, 2 parts of calcium fluoride, 6 parts of polyvinyl alcohol, 875 parts of manufactured sand, and 715 parts of crushed stone were placed in a mixer and forcibly stirred for 2 minutes. Then, 50 parts of readily soluble potassium silicate and 15 parts of sodium metasilicate pentahydrate were dissolved in 190 parts of water and added to the mixer. The mixture was forcibly stirred for 3 minutes to prepare compressive strength specimens (100×100×100mm) and frost resistance specimens (100×100×400mm). After 12 hours of casting, 20 parts of anhydrous sodium metasilicate were dissolved in 100 parts of water to prepare a solution. This solution was sprayed onto the surface of the cured geopolymer concrete specimens. One hour later, when the surface was dry, another layer was sprayed, for a total of three sprays. If the surface was not dry, the spraying time could be appropriately extended. After 24 hours, the mold was removed and the product was placed in a standard curing room for curing for 28 days.

[0038] The self-healing test and the antifreeze test are the same as in Example 1. Example 3

[0039] 365 parts of slag powder, 90 parts of decommissioned wind turbine blade powder, 52 parts of fly ash, 13 parts of nano-silica, 2 parts of decommissioned wind turbine blade fiber, 3 parts of calcium fluoride, 9 parts of polyvinyl alcohol, 850 parts of manufactured sand, and 696 parts of crushed stone were placed in a mixer and forcibly stirred for 2 minutes. Then, 55 parts of readily soluble potassium silicate and 17 parts of sodium metasilicate pentahydrate were dissolved in 200 parts of water, fully dissolved, and added to the mixer. The mixture was forcibly stirred for 3 minutes to prepare compressive strength specimens (100×100×100mm) and frost resistance specimens (100×100×400mm). Twelve hours after casting, 20 parts of anhydrous sodium metasilicate were dissolved in 100 parts of water to prepare a solution, which was sprayed onto the surface of the cured geopolymer concrete specimens. One hour later, when the surface was dry, a second spray was applied, for a total of three sprays. If the surface was not dry, the spraying time could be appropriately extended. After 24 hours, the mold was removed and the product was placed in a standard curing room for curing for 28 days.

[0040] The self-healing test and the antifreeze test are the same as in Example 1. Comparative Example 1

[0041] 250 parts of slag powder, 50 parts of decommissioned wind turbine blade powder, 25 parts of fly ash, 6 parts of nano-silica, 1 part of decommissioned wind turbine blade fiber, 968 parts of manufactured sand, and 788 parts of crushed stone were placed in a mixer and forcibly stirred for 2 minutes. Then, 48 parts of readily soluble potassium silicate and 12 parts of sodium metasilicate pentahydrate were dissolved in 180 parts of water and added to the mixer, and forcibly stirred for 3 minutes to prepare compressive strength test specimens (100×100×100mm) and frost resistance test specimens (100×100×400mm). After casting and molding, the specimens were removed from the mold and placed in a standard curing room for 28 days.

[0042] The self-healing test and the antifreeze test are the same as in Example 1. Comparative Example 2

[0043] 265 parts of slag powder, 60 parts of decommissioned wind turbine blade powder, 30 parts of fly ash, 8 parts of nano-silica, 1 part of decommissioned wind turbine blade fiber, 938 parts of manufactured sand, and 768 parts of crushed stone were placed in a mixer and forcibly stirred for 2 minutes. Then, 50 parts of readily soluble potassium silicate and 15 parts of sodium metasilicate pentahydrate were dissolved in 190 parts of water and added to the mixer, and forcibly stirred for 3 minutes to prepare compressive strength test specimens (100×100×100mm) and frost resistance test specimens (100×100×400mm). After casting and molding, the specimens were removed from the mold and placed in a standard curing room for 28 days.

[0044] The self-healing test and the antifreeze test are the same as in Example 1. Comparative Example 3

[0045] 280 parts of slag powder, 70 parts of decommissioned wind turbine blade powder, 40 parts of fly ash, 10 parts of nano-silica, 2 parts of decommissioned wind turbine blade fiber, 912 parts of manufactured sand, and 746 parts of crushed stone were placed in a mixer and forcibly stirred for 2 minutes. Then, 55 parts of readily soluble potassium silicate and 17 parts of sodium metasilicate pentahydrate were dissolved in 200 parts of water, fully dissolved, and added to the mixer. The mixture was then forcibly stirred for 3 minutes to prepare compressive strength test specimens (100×100×100mm) and frost resistance test specimens (100×100×400mm). After casting, the specimens were removed from the mold 24 hours later and placed in a standard curing room for 28 days of curing.

[0046] The self-healing test and the antifreeze test are the same as in Example 1.

[0047] Table 1. Experimental Results

[0048] Table 1 shows the test results, indicating that the 1-day and 28-day strengths of the examples were significantly improved compared to the comparative examples. This is attributed to the modification effects of calcium fluoride and polyvinyl alcohol, as well as the secondary alkali activation effect of the anhydrous sodium metasilicate solution. After the specimens underwent loading and destructive testing, and following 14 days of curing, the strengths of the examples all significantly increased, exceeding the original strength values, while the strengths of the comparative examples did not recover to their original values. Figure 2 All three examples recovered to over 100% of their original strength, with Example 3 achieving a recovery rate of 116.1%. The comparative examples also showed some strength recovery, but only reached 89.3%–93.0% of their original strength, failing to fully recover to their original values. (See attached image for details.) Figure 3 The results show that the three comparative examples, obtained through the technical optimization measures of this patent, possess self-healing capabilities, and their strength has recovered to above the original strength. Regarding ultrasonic wave velocity, the wave velocity decreased significantly after the loading failure test. After 14 days, the three comparative examples showed almost no significant fluctuations, while the three examples' wave velocity essentially recovered to pre-loading failure levels after 14 days, indicating that after 14 days of curing, the concrete interior became as dense as the original specimen. Freeze-thaw cycle tests showed that the examples exhibited significantly improved freeze-thaw resistance compared to the comparative examples. After 200 cycles, the mass loss rate of both the comparative examples and the examples did not exceed 5%, and the relative dynamic modulus of elasticity was greater than 60%, indicating that the comparative examples and the examples resisted freeze-thaw cycles greater than 200 cycles. The three comparative examples resisted freeze-thaw cycles between 200 and 250 cycles (Comparative Example 1: 200 cycles, Comparative Example 3: 250 cycles), while the examples' freeze-thaw resistance increased to 350-400 cycles, an improvement of 60%-75%. Impact and abrasion resistance also showed a significant improvement, increasing by 61.4%-72.8%.

[0049] In summary, as shown in Table 1, the concrete of Examples 1-3 of this invention is significantly superior to that of Examples 1-3 in terms of 1-day compressive strength, 28-day compressive strength, self-healing ability, frost resistance, and impact abrasion resistance. 1. Mechanical properties: The 1-day compressive strength of Examples 1-3 was 23.1-30.5 MPa, which was 151.1%-100.0% higher than that of Comparative Examples 1-3 (9.2-15.3 MPa); the 28-day compressive strength was 37.9-49.6 MPa, which was 27.2%-51.2% higher than that of Comparative Examples 1-3 (29.8-32.8 MPa). This shows that the raw material composition and preparation process of the present invention can significantly improve the early and late mechanical properties of concrete.

[0050] 2. Self-healing ability: After applying 80% ultimate load for 28 days, the compressive strength recovery rate of Examples 1-3 exceeded 100% after 14 days of curing, reaching a maximum of 116.1%, and the ultrasonic wave velocity basically recovered to the pre-damage level; while the strength recovery rate of Comparative Examples 1-3 was only 89.3% to 93.0%, and the ultrasonic wave velocity did not recover significantly. This proves that the super-abundant composite precursor and surface secondary excitation system of the present invention can effectively achieve self-healing of concrete damage.

[0051] 3. Freeze-thaw resistance: After 200 freeze-thaw cycles, the mass loss rate of Examples 1-3 was only 1.1%-2.8%, the relative dynamic modulus of elasticity was 86%-95%, and the number of freeze-thaw cycles reached 350-400; after 200 freeze-thaw cycles, the mass loss rate of Comparative Examples 1-3 was 3.9%-4.8%, the relative dynamic modulus of elasticity was 62%-73%, and the number of freeze-thaw cycles was only 200-250. This shows that the present invention can significantly improve the freeze-thaw resistance of concrete and is suitable for cold environments.

[0052] 4. Abrasion resistance: The abrasion resistance of Examples 1-3 is 16.52-19.82 h / (kg / m²), which is 72.8%-61.4% higher than that of Comparative Examples 1-3 (9.56-12.28 h / (kg / m²)). This indicates that the concrete of the present invention has better abrasion resistance and is suitable for water flow scouring parts of hydraulic structures.

[0053] Comparative Examples 1-3 of this patent can be used in hydraulic concrete, meeting the needs of concrete structures in water conservancy projects. After a series of optimizations by this patent, Examples 1-3 were obtained, with significantly improved freeze-thaw resistance and abrasion resistance. In particular, they possess self-healing capabilities, with strength recovery rates exceeding 100%, surpassing the original strength. The ultrasonic wave velocity inside the concrete also recovered to its pre-damage state. In cold-region water conservancy projects, when concrete is initially damaged by loads or freeze-thaw cycles, microcracks form at the damaged areas. After water seeps in, it dissolves the remaining anhydrous sodium metasilicate sprayed after curing and repeatedly activates the excess precursor with alkali, repairing and reinforcing the cracks at the damaged areas. This significantly improves the overall performance of the geopolymer-based self-healing concrete for cold-region hydraulic engineering provided by this patent, making it fully applicable to concrete structures in underground tunnels and water level fluctuation zones in severely cold regions. Simultaneously, it fully utilizes emerging solid waste, replacing traditional silicate cement, thereby effectively reducing production energy consumption and carbon emissions. It is a new type of green concrete material with broad application prospects in the future.

[0054] In summary, the geopolymer-based self-healing concrete for cold-region hydraulic engineering and its preparation method provided by this invention successfully combine the green characteristics of geopolymers with intelligent self-healing functions, achieving excellent comprehensive performance with high strength, high durability (especially frost resistance and wear resistance) and active damage repair. It is particularly suitable for application in cold-region hydraulic and hydropower projects with harsh environments and inconvenient maintenance, and has important engineering application value and promotion prospects.

[0055] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A geopolymer-based self-healing hydraulic concrete for cold regions, characterized in that, The main ingredients are composed of the following raw materials in parts by weight: 325-365 parts slag powder, 65-90 parts decommissioned wind turbine blade powder, 33-52 parts fly ash, 8-13 parts nano silica, 48-55 parts readily soluble potassium silicate, 20 parts anhydrous sodium metasilicate, 12-17 parts sodium metasilicate pentahydrate, 1-2 parts decommissioned wind turbine blade fiber, 1-3 parts calcium fluoride, 3-9 parts polyvinyl alcohol, 850-905 parts manufactured sand, 696-740 parts crushed stone, and 180-200 parts water. The slag powder, decommissioned wind turbine blade powder, fly ash and nano silica constitute an excessive composite precursor, and its total usage is 1.3 times that of the baseline precursor usage. The fast-dissolving potassium silicate and sodium metasilicate pentahydrate form a composite alkaline activator. The anhydrous sodium metasilicate solution is used for spraying treatment on the surface of the cured concrete. The slag powder is grade S95, with a specific surface area of ​​not less than 400 m² / kg; the fineness of the decommissioned wind turbine blade powder is not less than 200 mesh; the monofilament diameter of the decommissioned wind turbine blade fiber is 5 μm, and the length is 3-5 mm; the fly ash is grade I or II; the nano-silica is a white powder with a particle size of 5-100 nm; the modulus of the readily soluble potassium silicate is 2.3-2.5; the anhydrous sodium metasilicate is an industrial-grade white powder with a density of 2.4 g / cm³; the fineness of the pentahydrate sodium metasilicate is 60 mesh; the fineness of the calcium fluoride is 100 mesh, and the loss on ignition is ≤0.6%; the polyvinyl alcohol is a dry powder mixture with a fineness of 160 mesh; the fineness modulus of the manufactured sand is 2.4-2.8; and the particle size of the crushed stone is 5-20 mm.

2. A method for preparing geopolymer-based self-healing hydraulic concrete for cold regions as described in claim 1, characterized in that, Includes the following steps: Step S1, Premix preparation: Mix the slag powder, decommissioned wind turbine blade powder, fly ash, nano silica, decommissioned wind turbine blade fiber, calcium fluoride, polyvinyl alcohol, manufactured sand and crushed stone according to the weight parts of claim 1, and mix them with forced stirring for 2 minutes until uniform to obtain a dry mixture. Step S2: Prepare slurry: Dissolve the parts by weight of fast-dissolving potassium silicate and sodium metasilicate pentahydrate as described in claim 1 in the parts by weight of water as described in claim 1, and add the solution to a mixer after it is fully dissolved. Then, use forced stirring for 3 minutes. Step S3, Casting and Shaping: The concrete should be leveled and vibrated in time after being poured into the formwork. No water should be added to the formwork during the pouring process. Step S4, Surface spraying treatment: 12 hours after casting and molding, dissolve the anhydrous sodium metasilicate of the weight specified in claim 1 in 100 parts of water to prepare a solution, and spray it onto the surface of the cured geopolymer concrete. After 1 hour, when the surface is dry, spray it again, for a total of 3 sprays. If the surface is not dry, the spraying time can be appropriately extended. Step S5, Maintenance: After completing the surface spraying treatment, carry out water curing for 7 to 14 days.

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