Memory alloy fiber and recycled sand powder ecc functional material, preparation method and application thereof

Abstract

The application discloses a kind of memory alloy fiber and regenerative sand powder ECC functional materials, its preparation method and application, belong to building material field.The application is through the way of fiber hybrid and formula optimization, fully utilizes building waste resource regeneration powder technology, further promotes the high ductility and self-healing of ECC material, can form fine and uniform crack when being loaded, substantially improves the durability and disaster resistance of structure, and preparation method is simple and easy.

Description

Technical Field

[0001] This invention relates to a shape memory alloy fiber and recycled sand powder ECC functional material, its preparation method and application, belonging to the field of building materials. Background Technology

[0002] With the advancement of urbanization and rapid economic development, the amount of construction waste is increasing year by year. Faced with this situation, the transformation and upgrading of the industry is urgently needed. Considering that construction solid waste contains a large amount of sintered red bricks and waste concrete, how to utilize these wastes as resources has become a new direction for the development of the construction industry. Through deep grinding, synergistic heating, and drying of solid waste, recycled brick sand and recycled micro-powder can be prepared, and their high-value utilization is of great significance to promoting the development of green building materials. Engineering cement-based composite materials (ECC), as a type of high-ductility cement-based composite material, are gradually becoming a research and application hotspot in the field of materials due to their excellent tensile strain hardening and multi-crack characteristics, particularly in the repair of building structures, seismic reinforcement, and the preparation of new components. While traditional ECC materials possess the advantage of high ductility, cracks are difficult to self-heal after they develop, making them highly susceptible to external erosion and reducing the service life of the structure. Currently, some studies improve the ductility of ECC by incorporating single fibers or achieving self-healing by adding external healing agents, but these often suffer from uneven crack distribution and difficulty in simultaneously achieving high ductility, self-healing, and high-value utilization of construction solid waste. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide an ECC functional material with excellent high ductility and self-healing properties, its preparation method and application.

[0004] Technical Solution: The shape memory alloy fiber and recycled sand powder ECC functional material of the present invention comprises the following components by weight: 52.5 cement: 1.0 part; recycled sand powder: 1.1-15.0 parts; fly ash: 0.1-2.0 parts; silica fume: 0.1-2.0 parts; nano silica: 0.01-0.1 parts; cellulose ether: 0.01-0.1 parts; shape memory alloy fiber: 0.01-0.5 parts; PE fiber: 0.02-0.5 parts; polycarboxylate superplasticizer: 0.01-0.1 parts; water: 0.1-3.0 parts.

[0005] This application achieves a synergistic effect of high ductility and self-healing function in ECC materials by blending shape memory alloy fibers with PE fibers. This solves the technical problem that traditional ECC materials only have high ductility but no self-healing function, significantly improving the durability and service life of the materials. Recycled brick sand and recycled micro powder are used as crack inducing agents. Their porous characteristics and heterogeneous particle gradation form micro-stress concentration zones inside the material, providing crack formation points under load and avoiding the generation of single wide cracks, thus significantly improving the tensile ductility and crack resistance of the materials. At the same time, the resource-based products of construction solid waste replace some natural aggregates and cementitious materials, realizing the rational utilization of construction solid waste and reducing the consumption of natural resources and the disposal cost of construction solid waste.

[0006] Furthermore, the recycled sand powder includes recycled micro powder and recycled brick sand, with recycled micro powder comprising 0.1-5.0 parts and recycled brick sand comprising 1.0-10.0 parts.

[0007] Further, the functional material comprises the following components: 1.0 part of 52.5 cement; 1.1-10.0 parts of recycled sand powder; 0.1-2.0 parts of fly ash; 0.1-2.0 parts of silica fume; 0.01-0.15 parts of nano-silica; 0.01-0.15 parts of cellulose ether; 0.01-0.5 parts of shape memory alloy fiber; 0.02-0.5 parts of PE fiber; 0.01-0.1 parts of polycarboxylate superplasticizer; and 0.1-3.0 parts of water; wherein the recycled micro powder is 0.1-5.0 parts and the recycled brick sand is 1.0-5.0 parts.

[0008] Further, the functional material comprises the following components: 1.0 part of 52.5 cement; 3.5-10.0 parts of recycled sand powder; 0.1-2.0 parts of fly ash; 0.1-2.0 parts of silica fume; 0.01-0.15 parts of nano-silica; 0.01-0.15 parts of cellulose ether; 0.01-0.5 parts of shape memory alloy fiber; 0.02-0.5 parts of PE fiber; 0.01-0.1 parts of polycarboxylate superplasticizer; and 0.1-3.0 parts of water; wherein the recycled micro powder is 1.5-5.0 parts and the recycled brick sand is 2.0-5.0 parts.

[0009] Further, the functional material comprises the following components: 52.5 cement: 1.0 part; recycled sand powder: 3.5-10.0 parts; fly ash: 0.4 parts; silica fume: 0.4 parts; nano silica: 0.15 parts; cellulose ether: 0.15 parts; shape memory alloy fiber: 0.03 parts; PE fiber: 0.02 parts; polycarboxylate superplasticizer: 0.02 parts; water: 1.5 parts; wherein recycled micro powder comprises 1.5-5.0 parts and recycled brick sand comprises 2.0-5.0 parts.

[0010] Furthermore, the recycled micro powder is a fine powder made by grinding a mixture of waste concrete and waste bricks and tiles, with a particle size ≤75 μm, and recycled micro powder with a particle size ≤45 μm accounts for ≥70% of the total recycled micro powder, of which waste bricks and tiles account for 10-90% of the mass percentage of the recycled micro powder.

[0011] Furthermore, the recycled brick sand is powder made from ground waste red bricks with a particle size of 0.15-5 mm.

[0012] Furthermore, the cellulose ether includes one or more of methylcellulose ether, hydroxyethylcellulose ether, hydroxypropyl methylcellulose ether, carboxymethylcellulose ether, and ethyl hydroxyethylcellulose ether.

[0013] Furthermore, the polycarboxylate superplasticizer has a solid content of 20-40% and a water reduction rate of ≥25%.

[0014] Furthermore, the shape memory alloy fiber is a NiTi alloy fiber.

[0015] The method for preparing a shape memory alloy fiber and recycled sand powder ECC functional material according to the present invention is characterized by comprising the following steps: (1) Mix cement, recycled sand powder, fly ash, silica fume, nano silica and cellulose ether, stir evenly to obtain a premixed compound; (2) Add water and polycarboxylate superplasticizer to the premix and stir. After mixing evenly, add PE fiber in batches while stirring. Stir until the fiber is evenly distributed, then slowly add shape memory alloy fiber. Stir evenly to obtain the final mixture. (3) The final mixture is then placed into a mold for curing.

[0016] Furthermore, the PE fibers are added in 3-5 portions.

[0017] The present invention relates to the application of the above-mentioned shape memory alloy fiber and recycled sand powder ECC functional material in the preparation of building materials.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention makes full use of the resource-based recycled powder technology of construction waste through fiber blending and formula optimization, further improving the high ductility and self-healing of ECC materials, which can form fine and uniform cracks under load, greatly improving the durability and disaster resistance of the structure, and the preparation method is simple and easy to implement. Attached Figure Description

[0019] Figure 1 This is a comparison of the performance differences of the materials prepared in the comparative examples and embodiments of the present invention.

[0020] Figure 2The tensile strain results of the material prepared as a comparative example of the present invention are shown.

[0021] Figure 3 The tensile strain results of the materials prepared in the embodiments of the present invention are shown. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0023] The following is a memory alloy fiber and recycled sand powder ECC functional material of the present invention and its preparation process: Take 1.0 part of 52.5 cement, 0.1-5.0 parts of recycled micro powder, 0.1-2.0 parts of fly ash, 0.1-2.0 parts of silica fume, 0.01-0.1 parts of nano silica, 0.01-0.1 parts of cellulose ether, and 1.0-10.0 parts of recycled brick sand, mix them evenly, and obtain a premixed compound.

[0024] Measure 0.1-3.0 parts of water and 0.01-0.1 parts of polycarboxylate superplasticizer and add them to the premixed mixture. Stir until the mixture is uniform. Then, while stirring, add 0.02-0.5 parts of PE fiber in 3-5 batches until the fiber is uniformly dispersed. Finally, slowly add 0.01-0.5 parts of shape memory alloy fiber and stir until the mixture is uniform to obtain the final mixture.

[0025] The final mixture obtained is then poured into a mold, thoroughly vibrated, and the entire mold is covered with plastic wrap. Standard curing is performed at a temperature of 18-22℃, a humidity of 85-95%, and a curing period of 28 days. Finally, ultra-high performance shape memory alloy fiber and recycled sand powder ECC functional material is obtained.

[0026] Raw material requirements: The cement is either silicate cement or ordinary silicate cement, and its strength grade is 52.5. In this example, the cement is Conch brand Portland cement produced by Anhui Conch Cement Co., Ltd., which is silicate cement.

[0027] The recycled micro powder is made by grinding construction waste into fine powder with a particle size ≤75 μm. The construction waste is a mixture of waste concrete and waste bricks and tiles. The impurity content in the construction waste is <0.1%, the original strength grade of the waste concrete is ≥C20, the original strength grade of the waste bricks and tiles is ≥MU5.0, and the mass percentage of waste bricks and tiles in the construction waste is 10-90%. The recycled micro powder is used in a completely dry state. The pretreatment before use is to place the recycled micro powder in a drying oven and dry it at 100-110℃ for 24 h, and the mass change of the active recycled micro powder is <0.1%. Among them, the recycled micro powder with a particle size ≤45 μm accounts for ≥70% of the total recycled micro powder. In the example, the recycled micro powder was prepared by the company after obtaining waste concrete and waste bricks and tiles (from Shandong Kangjing New Material Technology Co., Ltd.).

[0028] Fly ash is a fine powder with a particle size of ≤45 μm collected from coal-fired power plants. In this example, the fly ash comes from Henan Borun Foundry Materials Co., Ltd.; silica fume is an ultrafine, highly active mineral admixture with a particle size of 0.1-0.3 μm. In this example, the silica fume comes from Shandong Boken Silicon Materials Co., Ltd.; recycled brick sand is made by crushing waste red bricks into particles with a particle size of 0.15-5 mm. The original strength grade of the waste red bricks is ≥MU10, and the impurity content is <0.1%. The recycled brick sand is soaked in water for 24 hours to allow the pores to fully absorb water and the outer surface of the particles to be free of free water, so that it is in a saturated surface-dry state. In this example, the recycled brick sand is prepared by the company after obtaining waste red bricks (from Zhejiang Hongjin Renewable Resources Co., Ltd.).

[0029] The particle size range of nano-silica is ≤100 nm. In this example, the nano-silica is sourced from Zhongyu Wohao New Materials Co., Ltd. The shape memory alloy fiber (SMA fiber) is NiTi alloy fiber with an ultimate tensile strength ≥700 MPa, an elastic modulus of the parent phase ≥50 GPa, a temperature recovery force ≥300 MPa, and a length range of 15-60 mm. In this example, the NiTi alloy fiber is sourced from Kunshan Jinanjia New Materials Co., Ltd. The elastic modulus of PE fiber is 91-140 N / tex, and the length range is 6-20 mm. In this example, the PE fiber is sourced from Shandong Taihe New Materials Co., Ltd. The cellulose ether is hydroxypropyl methylcellulose ether, sourced from Shanghai Chenqi Chemical Technology Co., Ltd. The water-reducing agent used is a conventionally used polycarboxylate high-efficiency water-reducing agent (water reduction rate ≥25%, air content ≤2.0%). In this example, the water-reducing agent used is sourced from Shanxi Feike New Materials Technology Co., Ltd. The water is ordinary tap water.

[0030] Compare with Example 1 Measure 2.5 parts of 52.5 cement, 0.4 parts of fly ash, 0.4 parts of silica fume, 0.15 parts of nano silica, 0.15 parts of cellulose ether, and 2.0 parts of quartz sand, and mix for 3 minutes to obtain a premix. Measure 1.5 parts of water and 0.02 parts of polycarboxylate superplasticizer and add them to the premix, mixing thoroughly. Then, add 0.02 parts of PE fiber in 5 batches to the cement mixer and mix for 3 minutes each time to obtain the final mixture.

[0031] The cement used is selected from silicate cement. Fly ash is a fine powder with a particle size ≤45 μm collected from coal-fired power plants; silica fume is an ultrafine, highly active mineral admixture with a particle size of 0.1-0.3 μm. Quartz sand is obtained from crushed natural ore and dry-screened according to GB / T 14684-2022 using a standard square-hole sieve (4.75-0.15 mm) for 10 min of vibrating screening; gradation is controlled according to Class I, Zone 2, with a fineness modulus of 2.6-3.0, harmful impurity content <0.1%, dense and stable raw stone texture, and completely dry; qualified quartz sand accounts for ≥90% of the total quartz sand. The particle size range of nano-silica is ≤25 nm. The elastic modulus of PE fiber is 91-140 N / tex, and the length range of PE fiber is 12-15 mm. The cellulose ether is hydroxyethyl cellulose ether. The water-reducing agent is polycarboxylate high-efficiency water-reducing agent. The water is tap water.

[0032] The final mixture obtained is then poured into a mold, thoroughly vibrated, and the entire mold is covered with plastic wrap. After the specimen has initially set, the mold is removed and placed in a curing chamber for standard curing. The standard curing temperature is 18-22℃, the standard curing humidity is 85-95%, and the standard curing period is 28 days.

[0033] Compare with Example 2 Measure 2.5 parts of 52.5 cement, 0.4 parts of fly ash, 0.4 parts of silica fume, 0.15 parts of nano-silica, 0.15 parts of cellulose ether, and 2.0 parts of quartz sand, and mix for 3 minutes to obtain a premix. Then, measure 1.5 parts of water and 0.02 parts of polycarboxylate superplasticizer and add them to the premix, mixing for 3 minutes. While mixing, add 0.02 parts of PE fiber in 5 batches until the fiber is evenly dispersed. Then, slowly add 0.01 parts of shape memory alloy fiber to the cement mixer and mix for 3 minutes to obtain the final mixture.

[0034] Among them, the shape memory alloy fiber (SMA fiber) is a NiTi alloy fiber with a length range of 30-40 mm. The other materials are the same as those in Comparative Example 1.

[0035] Then pour the final mixture into the mold, vibrate it thoroughly, and cover the entire mold with plastic wrap for curing.

[0036] Compare with Example 3 Measure 2.5 parts of 52.5 cement, 0.4 parts of fly ash, 0.4 parts of silica fume, 0.15 parts of nano-silica, 0.15 parts of cellulose ether, and 2.0 parts of recycled brick sand, and mix for 3 minutes to obtain a premix. Then, measure 1.5 parts of water and 0.02 parts of polycarboxylate superplasticizer and add them to the premix, mixing for 3 minutes. While mixing, add 0.02 parts of PE fiber in 5 batches until the fiber is evenly dispersed. Then, slowly add 0.01 parts of shape memory alloy fiber to the cement mixer and mix for 3 minutes to obtain the final mixture.

[0037] The recycled brick sand has a particle size of 1-3 mm, the impurity content of the building red bricks used in the recycled brick sand is <0.1%, and the original strength grade of the waste red bricks is ≥MU15. The other materials are the same as in Comparative Example 2.

[0038] Then pour the final mixture into the mold, vibrate it thoroughly, and cover the entire mold with plastic wrap for curing.

[0039] Compare with Example 4 Measure 1.0 part of 52.5 cement, 2.0 parts of recycled micro powder, 0.4 parts of fly ash, 0.4 parts of silica fume, 0.15 parts of nano silica, 0.15 parts of cellulose ether, and 2.0 parts of quartz sand, and mix for 2 minutes to obtain a premix. Then, measure 1.5 parts of water and 0.02 parts of polycarboxylate superplasticizer and add them to the premix, mixing for 3 minutes. Then, while mixing, add 0.02 parts of PE fiber in 5 batches until the fiber is evenly dispersed. Finally, slowly add 0.01 parts of shape memory alloy fiber to the cement mixer and mix for 4 minutes to obtain the final mixture.

[0040] In the preparation of the recycled micro powder, waste bricks and tiles accounted for 70% of the total construction waste by mass, the impurity content in the construction waste was <0.1%, the original strength grade of the waste concrete was C20, and the original strength grade of the waste bricks and tiles was MU5.0. The recycled micro powder was in a completely dry state, with recycled micro powder with a particle size ≤30 μm accounting for ≥90% of the total recycled micro powder by mass, and the remaining recycled micro powder having a particle size ≤75 μm. Qualified quartz sand accounted for ≥90% of the total quartz sand by mass. The remaining materials were the same as in Comparative Example 2.

[0041] Then pour the final mixture into the mold, vibrate it thoroughly, and cover the entire mold with plastic wrap for curing.

[0042] Example 1

[0043] Measure 1.0 part of 52.5 cement, 0.1 part of recycled micro powder, 0.4 part of fly ash, 0.4 part of silica fume, 0.15 part of nano silica, 0.15 part of cellulose ether, and 1.0 part of recycled brick sand, and mix for 3 minutes to obtain a premix. Measure 1.5 parts of water and 0.02 parts of polycarboxylate superplasticizer and add them to the premix, mixing for 3 minutes. Then, while mixing, add 0.02 parts of PE fiber in 5 batches until the fiber is evenly dispersed. Finally, slowly add 0.01 parts of shape memory alloy fiber to the cement mixer and mix until the fiber is evenly dispersed to obtain the final mixture.

[0044] The cement used is selected from silicate cement. In the construction waste used to prepare the recycled micro-powder, waste bricks and tiles account for 65% of the total construction waste by mass, the impurity content in the construction waste is <0.1%, the original strength grade of the waste concrete is C25, and the original strength grade of the waste bricks and tiles is MU5.0. The recycled micro-powder is in a completely dry state, with recycled micro-powder particles ≤30 μm accounting for ≥95% of the total recycled micro-powder, and the remaining recycled micro-powder particles ≤75 μm in size. Fly ash is a fine powder with a particle size ≤45 μm collected from coal-fired power plants; silica fume is an ultrafine, highly active mineral admixture with a particle size of 0.1-0.3 μm. The recycled brick sand has a particle size of 1-3 mm, the impurity content in the selected red bricks is <0.1%, the original strength grade of the waste red bricks is ≥MU15, and the recycled sand is in a saturated surface-dry state. The particle size range of nano-silica is ≤25 nm. The elastic modulus of PE fibers is 91-140 N / tex, and the length ranges from 12-15 mm. Shape memory alloy fibers (SMA fibers) are NiTi alloy fibers with an ultimate tensile strength ≥700 MPa, an elastic modulus of the parent phase ≥50 GPa, a temperature recovery force ≥300 MPa, and a length range of 30-40 mm. The cellulose ether is hydroxyethyl cellulose ether. The water-reducing agent is a polycarboxylate superplasticizer. The water is tap water.

[0045] The final mixture obtained is then poured into a mold, thoroughly vibrated, and the entire mold is covered with plastic wrap. After the specimen has initially set, the mold is removed and placed in a curing chamber for standard curing. The standard curing temperature is 18-22℃, the standard curing humidity is 85-95%, and the standard curing period is 28 days.

[0046] Example 2

[0047] Measure 1.0 part of 52.5 cement, 1.5 parts of recycled micro powder, 0.4 parts of fly ash, 0.4 parts of silica fume, 0.15 parts of nano-silica, 0.15 parts of cellulose ether, and 2.0 parts of recycled brick sand, and mix for 3 minutes to obtain a premix. Measure 1.5 parts of water and 0.02 parts of polycarboxylate superplasticizer and add them to the premix, mixing for 3 minutes. Then, while mixing, add 0.02 parts of PE fiber in 5 batches until the fiber is evenly dispersed. Finally, slowly add 0.03 parts of shape memory alloy fiber to the cement mixer and mix until the fiber is evenly dispersed to obtain the final mixture.

[0048] The material conditions are the same as in Example 1.

[0049] Then pour the final mixture into the mold, vibrate it thoroughly, and cover the entire mold with plastic wrap for curing.

[0050] Example 3

[0051] Measure 1.0 part of 52.5 cement, 5.0 parts of recycled micro powder, 0.4 parts of fly ash, 0.4 parts of silica fume, 0.15 parts of nano silica, 0.15 parts of cellulose ether, and 5.0 parts of recycled brick sand, and mix for 3 minutes to obtain a premix. Measure 1.5 parts of water and 0.02 parts of polycarboxylate superplasticizer and add them to the premix, mixing for 3 minutes. Then, while stirring, add 0.02 parts of PE fiber in 5 batches until the fiber is evenly dispersed. Finally, slowly add 0.5 parts of shape memory alloy fiber to the cement mixer and stir until the fiber is evenly dispersed to obtain the final mixture.

[0052] The material conditions are the same as in Example 1.

[0053] Then pour the final mixture into the mold, vibrate it thoroughly, and cover the entire mold with plastic wrap for curing.

[0054] Example 4

[0055] Measure 1.0 part of 52.5 cement, 5.0 parts of recycled micro powder, 0.4 parts of fly ash, 0.4 parts of silica fume, 0.15 parts of nano silica, 0.15 parts of cellulose ether, and 5.0 parts of recycled brick sand, and mix for 3 minutes to obtain a premix. Then, measure 1.5 parts of water and 0.02 parts of polycarboxylate superplasticizer and add them to the premix, mixing for 3 minutes. Then, while mixing, add 0.02 parts of PE fiber in 5 batches until the fiber is evenly dispersed. Finally, slowly add 0.01 parts of shape memory alloy fiber to the cement mixer and mix until the fiber is evenly dispersed to obtain the final mixture.

[0056] The material conditions are the same as in Example 1.

[0057] Then pour the final mixture into the mold, vibrate it thoroughly, and cover the entire mold with plastic wrap for curing.

[0058] The comprehensive performance of the materials prepared in Comparative Examples 1-4 and Examples 1-4 was evaluated, and the results are shown in Table 1.

[0059] The specimens used were standard dog bone ECC specimens with an overall length of 330 mm, an effective gauge length of 80 mm, and a cross-sectional thickness of 13 mm. Ultimate tensile strength, tensile strain, and crack width were routine performance tests, while the ECC self-healing rate test required calculation using the crack healing rate evaluation index. A universal testing machine was used to apply a 1.0% pre-tension strain to the specimen at a displacement rate of 0.5 mm / min to create controllable microcracks of 30-120 μm. Measurement points were marked in situ, and the initial crack width was measured. A pure water immersion curing regimen was then used, and the crack width was remeasured after 28 days. The crack healing rate was calculated using Formula 1. Data processing required at least three parallel specimens for each group, and outliers exceeding 20% ​​were removed before averaging to obtain the final self-healing rate.

[0060]

[0061] in The crack closure and healing rate; This represents the average width of the pre-crack. This represents the average suture width after healing.

[0062] Table 1. Comprehensive performance evaluation of different types of ECC material samples

[0063] Comparing Comparative Example 1 and Example 2, it can be seen that introducing renewable brick powder to replace cement and quartz sand in a conventional ECC matrix and then incorporating shape memory alloy fibers significantly improves the material's high ductility and self-healing ability. Compared to the conventional ECC of Comparative Example 1, the ultimate tensile strength of the ECC material in Example 2 increased from 6.12 MPa to 13.32 MPa, an increase of 117.6%; the tensile strain increased from 4.0% to 9.7%, an increase of 142.5%. Figure 2 and 3After cracking, the crack width decreased from 117 μm to 42 μm, a reduction of 64.1%; the self-healing rate increased from 21% to 89%, an increase of 323.8%, achieving a significant improvement in overall performance. Comparing Example 2 with Control Examples 2, 3, and 4 reveals that, to effectively address the limited improvement in ECC matrix strength and insignificant improvement in self-healing performance when using single-component SMA fibers, SMA combined with recycled brick sand, or SMA combined with recycled micropowder, this invention fully leverages the crack bridging and toughening effects and shape memory crack closure effects of SMA fibers by adjusting the SMA fiber dosage threshold; and optimizes the mixing ratio of recycled brick sand and recycled micropowder to act as crack inducing agents, providing uniformly distributed microcrack formation sites for the matrix, thereby achieving precise control over crack development. A multi-scale synergistic reinforcement system of SMA-recycled brick sand-recycled micropowder was constructed.

Claims

1. A shape memory alloy fiber and recycled sand powder ECC functional material, characterized in that, By weight, it comprises the following components: 52.5 cement: 1.0 part; recycled sand powder: 1.1-15.0 parts; fly ash: 0.1-2.0 parts; silica fume: 0.1-2.0 parts; nano silica: 0.01-0.15 parts; cellulose ether: 0.01-0.15 parts; shape memory alloy fiber: 0.01-0.5 parts; PE fiber 0.02-0.5 parts; polycarboxylate superplasticizer 0.01-0.1 parts; Water 0.1-3.0 parts.

2. The ECC functional material of shape memory alloy fiber and recycled sand powder according to claim 1, characterized in that, The recycled sand powder includes recycled micro powder and recycled brick sand, with recycled micro powder comprising 0.1-5.0 parts and recycled brick sand comprising 1.0-10.0 parts.

3. The ECC functional material of shape memory alloy fiber and recycled sand powder according to claim 2, characterized in that, The recycled micro powder is a fine powder made by grinding a mixture of waste concrete and waste bricks and tiles, with a particle size ≤75 μm, and recycled micro powder with a particle size ≤45 μm accounts for ≥70% of the total recycled micro powder, of which waste bricks and tiles account for 10-90% of the mass percentage of recycled micro powder.

4. The ECC functional material of shape memory alloy fiber and recycled sand powder according to claim 2, characterized in that, The recycled brick sand is powder made from ground waste red bricks, with a particle size of 0.15-5 mm.

5. The ECC functional material of shape memory alloy fiber and recycled sand powder according to claim 1, characterized in that, The cellulose ether includes one or more of methylcellulose ether, hydroxyethylcellulose ether, hydroxypropyl methylcellulose ether, carboxymethylcellulose ether, and ethyl hydroxyethylcellulose ether.

6. The ECC functional material of shape memory alloy fiber and recycled sand powder according to claim 1, characterized in that, The polycarboxylate superplasticizer has a solid content of 20-40% and a water reduction rate of ≥25%.

7. The ECC functional material of shape memory alloy fiber and recycled sand powder according to claim 1, characterized in that, The shape memory alloy fiber is a NiTi alloy fiber.

8. A method for preparing a shape memory alloy fiber and recycled sand powder ECC functional material according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Mix cement, recycled sand powder, fly ash, silica fume, nano silica and cellulose ether, stir evenly to obtain a premixed compound; (2) Add water and polycarboxylate superplasticizer to the premix and stir. After mixing evenly, add PE fiber in batches while stirring. Stir until the fiber is evenly distributed, then slowly add shape memory alloy fiber. Stir evenly to obtain the final mixture. (3) The final mixture is then placed into a mold for curing.

9. The preparation method according to claim 8, characterized in that, The PE fiber is added in 3-5 portions.

10. The application of the shape memory alloy fiber and recycled sand powder ECC functional material according to any one of claims 1-7 in the preparation of building materials.

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