Preparation method of functionalized geopolymer aggregate reinforced ultrahigh-ductility cement-based composite material

Abstract

The invention discloses a preparation method of a functionalized geopolymer aggregate reinforced ultra-high ductility cement-based composite material, which comprises the following steps: firstly, packaging functional components in a geopolymer to prepare a geopolymer aggregate; and introducing the geopolymer aggregate into the cement matrix to obtain the functionalized geopolymer aggregate reinforced ultrahigh-ductility cement-based composite material. The preparation method of the geopolymer aggregate comprises the following steps: uniformly mixing the raw material components including the fly ash, the mineral powder, the functional components and the alkali activator to form a mixture; adding water into the mixture to form slurry; and pouring the slurry into a mold, curing for 2-3 days, then crushing, and carrying out standard curing for 20-30 days to obtain the geopolymer aggregate. The functional component is a material which enables the cement-based composite material to have any one of a self-sensing function, an electromagnetic shielding function and a self-healing function. The cement-based composite material with ultrahigh ductility and multiple intelligent characteristics is prepared by compounding a geopolymer for packaging functional components with an ECC (Error Correction Coefficient) system.

Description

Technical Field

[0001] This invention relates to the field of cement-based composite materials technology, and in particular to a method for preparing an ultra-high ductility cement-based composite material reinforced with functionalized geopolymer aggregates. Background Technology

[0002] As civil engineering evolves towards intelligent, long-life, and specialized service environments, the functional requirements for engineering cementitious composites (ECCs) are increasingly stringent. These requirements include stress / damage self-sensing, electromagnetic interference shielding, and damage healing. Currently, the mainstream approach to achieving these functions is to directly incorporate relevant functional materials into the cement matrix, such as carbon fiber, carbon nanotubes, steel fiber, and superabsorbent polymers. However, directly mixing functional materials into the cement matrix has significant drawbacks: these materials are prone to performance degradation in strongly alkaline environments and during complex mixing processes; they are difficult to disperse; and their interfacial bonding with the matrix is ​​weak, leading to low functional efficiency and unstable performance. Furthermore, multiple functional materials may interfere with each other, making synergistic effects difficult within the same system.

[0003] Current research on functionalized engineering cement-based composite materials mainly focuses on the performance of the final composite material. The technical approach can be summarized as a physical mixing model of "matrix material + fiber + functional additives". In terms of self-sensing, conductive materials such as carbon fibers and carbon nanotubes are typically directly mixed with cement and aggregates. This method faces problems such as difficulty in dispersing conductive materials, easy agglomeration, high threshold for forming conductive networks, poor repeatability of sensing signals, and poor durability. In terms of electromagnetic shielding, steel fibers or carbon fibers are often directly incorporated, or iron-rich slag / red mud powder is used. This method results in a random distribution of functional phases, making it difficult to construct an efficient and continuous electromagnetic wave attenuation path, and high dosages can negatively impact the mechanical properties and workability of the matrix. In terms of self-healing, superabsorbent polymer (SAP) capsules or particles are directly incorporated into the mixture. In this method, SAP rapidly absorbs water in the initial mixing stage, potentially affecting workability and creating weak points at the interface with the cementitious matrix, leading to a decrease in the strength of the cement-based composite material.

[0004] Therefore, developing a method for preparing functionalized cement-based composite materials that can synergistically solve the above problems has become an urgent need for technological development in this field. Summary of the Invention

[0005] To address the aforementioned problems with existing technologies for functionalizing cement-based composite materials, this invention provides a method for preparing ultra-high ductility cement-based composite materials reinforced with functionalized geopolymer aggregates.

[0006] The present invention provides a method for preparing a functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material, comprising two steps: (1) The functional component is encapsulated inside the geopolymer to prepare the geopolymer aggregate; the functional component is a material that enables the cement-based composite material to have any one of the functions of self-sensing function, electromagnetic shielding function or self-healing function.

[0007] (2) Geopolymer aggregate is introduced into the cement matrix to obtain a functionalized geopolymer aggregate reinforced ultra-high ductility cement-based composite material.

[0008] In step (1), the method for preparing the geopolymer aggregate is as follows: The raw material components, including fly ash, mineral powder, functional ingredients and alkali activator, are mixed evenly to form a mixture; water is added to the mixture and stirred evenly to obtain a slurry; the slurry is poured into a mold and cured for 2-3 days, then crushed to aggregate particles with a particle size of 3-6mm, and then cured for 20-30 days to obtain geopolymer aggregate.

[0009] Depending on the selected functional components, cement-based composite materials with different functions (self-sensing function, electromagnetic shielding function, or self-healing function) are finally prepared.

[0010] Specifically, when the functional component is at least one of chopped carbon fibers, carbon nanotubes, graphite, and graphene, fly ash, mineral powder, functional component, alkali activator, and dispersant are mixed evenly to form a mixture. Water is added to the mixture and stirred evenly to obtain a slurry. The slurry is poured into a mold and cured for 2-3 days, then crushed to aggregate particles with a particle size of 3-6 mm, and then cured for 20-30 days to obtain geopolymer aggregate. The fly ash accounts for 50-80% of the total mass fraction of fly ash and mineral powder, with the remainder being mineral powder. The functional component accounts for 0.25%~1.0% of the total mass of fly ash and mineral powder; the dispersant is methylcellulose or hydroxypropyl methylcellulose, and its dosage is 20 wt% of the functional component. The alkali activator is anhydrous sodium silicate. A cement-based composite material with self-sensing function is prepared using this geopolymer aggregate.

[0011] When the functional components are iron-containing slag or red mud and chopped carbon fibers, the preparation method of the geopolymer aggregate is the same as above. Specifically, based on a total mass fraction of 100% for fly ash, mineral powder, and iron-containing slag or red mud, the mineral powder accounts for 20-50%, with the remainder being fly ash and iron-containing slag or red mud. The amount of chopped carbon fibers accounts for 0.25% to 1.0% of the total mass of fly ash, mineral powder, and iron-containing slag or red mud. A cement-based composite material with electromagnetic shielding function is prepared using this geopolymer aggregate.

[0012] Preferably, the chopped carbon fibers used above have undergone pre-modification treatment, and the modification method is as follows: Short carbon fibers (0.1 mm to 3.0 mm) are immersed in concentrated nitric acid and refluxed at 70-90°C for 2-3 hours, then washed until neutral. The acidified short carbon fibers are added to an ethanol solution containing a silane coupling agent and stirred at 50-70°C for 4-5 hours. After drying, modified short carbon fibers are obtained.

[0013] When the functional component is highly absorbent polymer (SAP), its dosage accounts for 0.1% to 0.3% of the total mass of fly ash and mineral powder. Fly ash, mineral powder, functional component, and alkali activator are mixed evenly to form a mixture. Water is added to the mixture and stirred evenly to obtain a slurry. The slurry is poured into a mold and cured for 2-3 days, then crushed to aggregate particles with a diameter of 3-6 mm, and then cured under standard conditions for 20-30 days to obtain geopolymer aggregate. Cement-based composite materials with self-healing function are prepared using this geopolymer aggregate.

[0014] Preferably, the highly absorbent polymer SAP has undergone pre-modification treatment, and the modification method is as follows: Tetraethyl orthosilicate and anhydrous ethanol were mixed and then ammonia was added to adjust the pH of the solution to 9-10. The dried SAP particles were added to the solution and stirred at 40°C to allow the tetraethyl orthosilicate to undergo a hydrolysis-condensation reaction, forming a SiO2 gel layer on the SAP surface. Finally, the mixture was vacuum dried to obtain white powdery nano-SiO2 modified SAP composite microspheres.

[0015] In step (2), the geopolymer aggregate is introduced into the cement matrix. The specific method is as follows: Cement, fly ash, and geopolymer aggregates are mixed evenly to form a mixture. Water and a water-reducing agent are added to the mixture, and the mixture is stirred at high speed to form a uniform and smooth slurry. Then, the stirring speed is reduced, and chopped fibers are slowly and evenly sprinkled into the slurry. The stirring speed is then increased again and stirred for several minutes until the chopped fibers are completely coated with the slurry. After static curing, a functionalized cement-based composite material is obtained. The chopped fibers are any one of polyethylene fibers, polyvinyl alcohol fibers, polypropylene fibers, or basalt fibers. The length of the chopped fibers is 6-18 mm, and the chopped fibers account for 1.5-2.0% of the volume of the cement-based composite material.

[0016] Compared with the prior art, the advantages of the present invention are: This invention provides a stable and reliable method for preparing functionalized ECC materials: functional components are pre-encapsulated in geopolymers to form geopolymer-based artificial aggregates, which are then introduced into the cement matrix to achieve the self-sensing, electromagnetic shielding, and self-healing properties of the ECC. Geopolymers, as a green cementitious material, not only possess early strength and corrosion resistance, but more importantly, they belong to the same aluminosilicate system as the cement matrix, exhibiting excellent chemical compatibility and interfacial bonding strength. This invention utilizes the unique "encapsulation effect" and "pore ion conductivity" of the geopolymer matrix. By using geopolymers as a carrier to pre-encapsulate functional components, the problem of functional component dispersion in cement is solved. Furthermore, through the robust aggregate-matrix interface, the material's intelligent properties are endowed while maintaining or even enhancing its mechanical properties. Specifically, this is manifested in the following aspects: (1) Solved the problem of dispersion and durability of traditional self-sensing ECC conductive phase: Through the technical path of "encapsulation first and then mixing", the nano- or micro-scale conductive phase (carbon fiber) is pre-uniformly solidified inside the artificial geopolymer aggregate, which fundamentally avoids the problem of agglomeration encountered when it is directly dispersed in the cement matrix.

[0017] (2) It solves the problem of difficult dispersion of conductive phase in traditional electromagnetic shielding ECC materials and reduces the impact of iron-rich slag / red mud on the strength of cement-based materials.

[0018] (3) It solves the problem of reduced strength of cement-based matrix after introducing SAP material into traditional self-healing ECC. SAP is encapsulated in geopolymer aggregate to construct a pre-defined pore structure, so that ECC can achieve self-healing ability during normal use.

[0019] (4) Achieving green materials and controllable design: Industrial solid wastes such as slag are used as the main raw materials for preparing geopolymer matrices and conductive aggregates, which is in line with the concept of green and low-carbon sustainable development. At the same time, by precisely controlling the dosage, particle size and gradation of functional aggregates, the "functional design" of ECC materials can be achieved to meet the specific needs of different engineering application scenarios.

[0020] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0021] Figure 1 These are test graphs of the self-sensing performance of the cement-based composite material prepared in Example 1 under compressive and tensile conditions. Among them, (a) is the test graph of self-sensing performance under compressive conditions, and (b) is the test graph of self-sensing performance under tensile conditions.

[0022] Figure 2The figures show the self-sensing performance test diagrams of the cement-based composite material prepared in Comparative Example 1 under compressive and tensile conditions. Among them, (a) is the self-sensing performance test diagram under compressive conditions, and (b) is the self-sensing performance test diagram under tensile conditions.

[0023] Figure 3 The graphs show the self-sensing performance test results of the cement-based material prepared in Comparative Example 2 under compressive and tensile conditions. Among them, (a) is the self-sensing performance test result under compressive conditions, and (b) is the self-sensing performance test result under tensile conditions.

[0024] Figure 4 This is a graph showing the electromagnetic shielding performance test results of the cement-based material prepared in Example 2 of the present invention.

[0025] Figure 5 These are the test results of the self-healing performance of the cement-based composite materials obtained in Example 3 and Comparative Example 3.

[0026] Figure 6 These are the test results of the compressive strength properties of the cement-based composite materials obtained in Example 3 and Comparative Example 3. Detailed Implementation

[0027] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0028] Example 1 A method for preparing an ultra-high ductility cement-based composite material with self-sensing function: (1) Preparation of geopolymer aggregate: Step 1: Immerse the carbon fiber in 65% concentrated nitric acid and reflux acidify it at 80°C for 2 hours to increase its surface active sites; after washing until neutral, place it in an ethanol solution containing 2wt% silane coupling agent (KH-550) and stir at 60°C for 4 hours to achieve chemical modification of silane molecules on the fiber surface. Finally, after drying, the modified carbon fiber is obtained.

[0029] Step 2: According to the raw material ratio shown in Table 1, add modified carbon fiber, fly ash, mineral powder, methylcellulose, and alkali activator (anhydrous sodium silicate) to a mortar mixer and mix at low speed for 2 minutes; then add water to the mixture and mix at high speed for 2 minutes to obtain a fresh slurry; pour the fresh slurry into a mold, cure for 2 days, and then crush it into fine aggregate with a diameter of less than or equal to 4.75 mm, and then cure it according to standard for 28 days to obtain geopolymer aggregate.

[0030] The allocation of each raw material group is shown in Table 1: Table 1. Raw material composition ratio for preparing geopolymer aggregate

[0031] (2) Preparation of cement-based composite materials: 500g of cement, 750g of fly ash, and 450g of geopolymer aggregate prepared in step (1) were placed in a mixer and mixed at low speed to form a mixture. 375g of water and 6.8g of water-reducing agent (NF-A naphthalene-based water-reducing agent) were added to the mixture and stirred at high speed to form a uniform and smooth slurry. Then the stirring speed was reduced and 26g of short-cut fibers (PVA fibers, 6-18 mm in length) were slowly and evenly sprinkled into the slurry. After all the fibers were added, the mixer was adjusted to high speed and stirred for 3 minutes until the fiber clumps were no longer visible to the naked eye and each fiber was wrapped in the slurry. Finally, the functionalized cement-based composite material was obtained after static curing.

[0032] Comparative Example 1 Based on Example 1, the modification of carbon fiber in step (1) is omitted (the first step is omitted), and the original carbon fiber is directly used to prepare the geopolymer aggregate according to the method in the second step. The geopolymer aggregate is used in step (2), and the raw material ratio and preparation method in step (2) are the same as in Example 1. Finally, a cement-based composite material is obtained.

[0033] Comparative Example 2 Based on Example 1, step (1) is omitted, and natural sand is used to replace the geopolymer aggregate in step (2) to finally obtain cement-based material.

[0034] Figure 1 , 2 Figures 3 and 4 show the self-sensing performance test diagrams of the cement-based materials prepared in Examples 1, 1, and 2 under compressive and tensile conditions, respectively. (a) shows the self-sensing performance test diagram under compressive conditions, and (b) shows the self-sensing performance test diagram under tensile conditions. As can be seen from the figures, the self-sensing performance of the cement-based composite material of Example 1 under both compressive and tensile conditions is comparable to that of the cement-based materials of Comparative Examples 1 and 2. Comparing Example 1 with Comparative Example 1, it can be concluded that carbon fiber modification can further improve the self-sensing performance of the cement-based composite material.

[0035] Example 2 A method for preparing an ultra-high ductility cement-based composite material with electromagnetic shielding function: (1) Preparation of geopolymer aggregate: Step 1: Immerse the carbon fiber in 65% concentrated nitric acid and reflux acidify it at 80°C for 2 hours to increase its surface active sites; after washing until neutral, place it in an ethanol solution containing 2wt% silane coupling agent (KH-550) and stir at 60°C for 4 hours to achieve chemical modification of silane molecules on the fiber surface. Finally, after drying, the modified carbon fiber is obtained.

[0036] Step 2: Prepare five different geopolymer aggregates according to the raw material composition ratio shown in Table 2. These are geopolymer aggregates without red mud and carbon fiber (referred to as Control), geopolymer aggregates without red mud but containing carbon fiber (referred to as CF-Control), and geopolymer aggregates containing different amounts of red mud and carbon fiber (referred to as RM20C0.5, RM40C0.5, and RM60C0.5).

[0037] Specific preparation method: Modified carbon fiber, fly ash, mineral powder, red mud, methylcellulose, and alkali activator (anhydrous sodium silicate) are added to a mortar mixer and stirred at low speed for 2 minutes; then water is added to the mixture and stirred at high speed for 2 minutes to obtain a fresh slurry; the fresh slurry is poured into a mold, cured for 2 days, and then crushed to fine aggregate with a diameter of less than or equal to 4.75 mm, and then cured for 28 days to obtain geopolymer aggregate.

[0038] In the above preparation method, for different geopolymer aggregates, unused raw material components are directly omitted, and the preparation steps remain unchanged.

[0039] Table 2. Raw material composition ratio for preparing geopolymer aggregate

[0040] (2) Cement-based materials were prepared using the five types of geopolymer aggregates obtained in step (1), and the preparation methods are as follows: 500g of cement, 750g of fly ash, and 450g of geopolymer aggregate prepared in step (1) were placed in a mixer and mixed at low speed to form a mixture. 375g of water and 6.8g of water-reducing agent (NF-A naphthalene-based water-reducing agent) were added to the mixture and stirred at high speed to form a uniform and smooth slurry. Then the stirring speed was reduced and 26g of short-cut fibers (PVA fibers, 6-18 mm in length) were slowly and evenly sprinkled into the slurry. After all the fibers were added, the mixer was adjusted to high speed and stirred for 3 minutes until no fiber clumps were visible to the naked eye and each fiber was wrapped in the slurry. Finally, the cement-based material was obtained after standing and curing.

[0041] The electromagnetic shielding performance test results of five cement-based materials prepared from five types of geopolymer aggregates are shown in the figure. Figure 4 In the figure, the control group is a cement-based material prepared using geopolymer Control. The carbon fiber control group is a cement-based material prepared using geopolymer CF-Control. RM20C0.5, RM40C0.5, and RM60C0.5 are cement-based composite materials prepared using these three geopolymer aggregates, respectively. As can be seen from the figure, the electromagnetic shielding performance of the ultra-high ductility cement-based composite materials (RM20C0.5, RM40C0.5, RM60C0.5) prepared by the method of this invention is significantly better than that of the control group and the carbon fiber control group.

[0042] Example 3 A method for preparing an ultra-high ductility cement-based composite material with self-healing function: (1) Preparation of geopolymer aggregate: Step 1: Preparation of Modified SAP Material: In this embodiment, the SAP material selected is an acrylic acid-acrylamide copolymer. Based on the core-shell modification method, the acrylic acid-acrylamide copolymer is surface modified. The method is as follows: Tetraethyl orthosilicate (TEOS) is used as the silicon source, and anhydrous ethanol is used as the solvent. They are mixed at a volume ratio of 1:5, and a small amount of ammonia is added as a catalyst to adjust the pH of the solution to 9-10. The dried acrylic acid-acrylamide copolymer particles are quickly added to the above modification solution. Utilizing the water absorption properties of the acrylic acid-acrylamide copolymer, it absorbs a small amount of solvent while anchoring TEOS molecules in the pores on the particle surface. Then, the mixture is continuously stirred at 40°C, causing the TEOS to undergo a hydrolysis-condensation reaction, forming a SiO2 gel layer on the surface of the acrylic acid-acrylamide copolymer. The modified acrylic acid-acrylamide copolymer is then vacuum dried to remove residual ethanol. Finally, nano-SiO2 modified acrylic acid-acrylamide copolymer composite microspheres with a white powdery texture and a relatively hard feel are obtained, i.e., modified SAP.

[0043] Step 2: Mix 800g fly ash, 200g mineral powder, 1g modified SAP, and 120g alkali activator (anhydrous sodium silicate) in a mortar mixer at low speed for 2 minutes. Add water to the mixture and mix at high speed for 2 minutes to obtain a fresh slurry. Pour the slurry into a mold and cure for 2 days. Then crush the slurry into fine aggregate with a diameter of less than or equal to 4.75 mm. Then cure for 28 days to obtain geopolymer aggregate.

[0044] (2) Preparation of cement-based composite materials: 500g of cement, 750g of fly ash, and 450g of geopolymer aggregate prepared in step (1) were placed in a mixer and mixed at low speed to form a mixture. 375g of water and 6.8g of water-reducing agent (NF-A naphthalene-based water-reducing agent) were added to the mixture and stirred at high speed to form a uniform and smooth slurry. Then the stirring speed was reduced and 26g of short-cut fibers (PVA fibers, 6-18 mm in length) were slowly and evenly sprinkled into the slurry. After all the fibers were added, the mixer was adjusted to high speed and stirred for 3 minutes until the fiber clumps were no longer visible to the naked eye and each fiber was wrapped in the slurry. Finally, the functionalized cement-based composite material was obtained after static curing.

[0045] Comparative Example 3 Based on Example 3, step (1) directly uses unmodified acrylic acid-acrylamide copolymer (unmodified SAP) to prepare geopolymer aggregate, and step (2) remains unchanged, finally obtaining cement-based composite material.

[0046] The self-healing performance test results of the cement-based composite materials obtained in Example 3 and Comparative Example 3 are as follows: Figure 5 As shown, compared with unmodified SAP, the cement-based composite material prepared from the nano-SiO2 modified SAP material in Example 3 exhibits better crack healing performance, reducing the crack width from 648 μm to 190 μm, with a healing rate of approximately 70.68%. This demonstrates that pre-modifying the SAP material with nano-SiO2 in the method of the present invention can further improve the self-healing performance of cement-based composite materials.

[0047] The compressive strength test results of the cement-based composite materials obtained in Example 3 and Comparative Example 3 are as follows: Figure 6 As shown in the figure, the compressive strength of the cement-based composite material prepared by the modified SAP in Example 3 is superior to that of the unmodified group at all ages. This indicates that pre-modification of SAP materials with nano-SiO2 can improve the mechanical properties of cement-based composite materials, achieving a dual improvement in self-healing and mechanical properties.

[0048] In summary, the preparation method of the functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material of the present invention mainly utilizes the excellent chemical compatibility and physical adhesion between the artificial geopolymer aggregate and the cement matrix to optimize the aggregate-matrix interface transition zone. This ensures that the composite material achieves functional properties without sacrificing its core tensile strain hardening and multi-crack characteristics, and even achieves synergistic enhancement of mechanical properties through micromechanical design. While guaranteeing reliable functional properties (self-sensing, electromagnetic shielding, and self-healing), the mechanical properties of the material are not reduced.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material, characterized in that, It includes the following two steps: (1) The functional component is encapsulated inside the geopolymer to prepare the geopolymer aggregate; the functional component is a material that enables the cement-based composite material to have any one of the functions of self-sensing function, electromagnetic shielding function or self-healing function; (2) Geopolymer aggregate is introduced into the cement matrix to obtain a functionalized geopolymer aggregate reinforced ultra-high ductility cement-based composite material.

2. The method for preparing the functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material as described in claim 1, characterized in that, The specific method for step (1) is as follows: The raw material components, including fly ash, mineral powder, functional ingredients and alkali activator, are mixed evenly to form a mixture; water is added to the mixture and stirred evenly to obtain a slurry; the slurry is poured into a mold and cured for 2-3 days, then crushed to aggregate particles with a particle size of 3-6mm, and then cured for 20-30 days to obtain geopolymer aggregate.

3. The method for preparing the functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material as described in claim 2, characterized in that, In step (1), the functional component is at least one of short-cut carbon fiber, carbon nanotube, graphite, and graphene, and its dosage accounts for 0.25% to 1.0% of the total mass of fly ash and mineral powder. The prepared cement-based composite material has a self-sensing function.

4. The method for preparing the functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material as described in claim 2, characterized in that, In step (1), the functional components are iron-containing slag or red mud and short-cut carbon fibers; the prepared cement-based composite material has electromagnetic shielding function.

5. The method for preparing the functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material as described in claim 3 or 4, characterized in that, The chopped carbon fibers were pre-modified using the following method: Short-cut carbon fibers are immersed in concentrated nitric acid and refluxed at 70-90℃ for 2-3 hours, then washed until neutral. The acidified short-cut carbon fibers are added to an ethanol solution containing a silane coupling agent and stirred at 50-70℃ for 4-5 hours. After drying, modified short-cut carbon fibers are obtained.

6. The method for preparing the functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material as described in claim 3 or 4, characterized in that, The raw material components for preparing geopolymer aggregates also include a dispersant, wherein the dispersant is methylcellulose or hydroxypropyl methylcellulose.

7. The method for preparing the functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material as described in claim 2, characterized in that, In step (1), the functional component is highly absorbent polymer SAP, which accounts for 0.1% to 0.3% of the total mass of fly ash and mineral powder. The prepared cement-based composite material has a self-healing function.

8. The method for preparing the functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material as described in claim 7, characterized in that, The highly absorbent polymer SAP was pre-modified using the following method: Tetraethyl orthosilicate and anhydrous ethanol were mixed and then ammonia was added to adjust the pH of the solution to 9-10. The dried SAP particles were added to the solution and stirred at 40°C to allow the tetraethyl orthosilicate to undergo a hydrolysis and condensation reaction, forming a SiO2 gel layer on the SAP surface. Finally, the mixture was vacuum dried to obtain white powdery nano-SiO2 modified SAP composite microbeads.

9. The method for preparing the functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material as described in claim 1, characterized in that, The specific method for introducing geopolymer aggregates into the cement matrix is ​​as follows: Cement, fly ash, and geopolymer aggregates are mixed evenly to form a mixture. Water and water-reducing agent are added to the mixture, and the mixture is stirred at high speed to form a uniform and smooth slurry. Then the stirring speed is reduced, and short-cut fibers are slowly and evenly sprinkled into the slurry. The stirring speed is then increased and stirred for several minutes until the short-cut fibers are completely coated with the slurry. After static curing, functionalized cement-based composite material is obtained.

10. The method for preparing the functionalized geopolymer aggregate-reinforced ultra-high ductility cementitious composite material as described in claim 7, characterized in that, The chopped fibers are any one of polyethylene fibers, polyvinyl alcohol fibers, polypropylene fibers, or basalt fibers.

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