Quick-setting recycled concrete for rush repair and construction and preparation method of quick-setting recycled concrete

Abstract

The method comprises the following steps: weighing water, cement, fly ash, natural river sand, recycled coarse aggregate, a water reducing agent, a liquid alkali-free accelerator and copper-plated steel fibers, uniformly mixing the cement and the fly ash to obtain a cementing material, reserving a part of the water, and uniformly mixing the cement and the fly ash to obtain the quick-setting recycled concrete for emergency repair and construction. Mixing the natural river sand and the cementing material, performing dry stirring, then adding the remaining water and the water reducing agent, performing stirring, then adding the copper-plated steel fiber and the recycled coarse aggregate, performing stirring, adding the liquid alkali-free accelerator and the reserved water into the obtained mixture, and performing stirring so as to obtain a concrete mixture in a gel state; and filling the concrete mixture in the gel state into a mold, vibrating, standing, demolding and curing to obtain the quick-setting recycled concrete for emergency repair and rush building. The quick-setting recycled concrete has the advantages of short setting time, high mechanical strength, stable chemical property and the like, and has good economical efficiency and environmental protection property.

Description

Technical Field

[0001] The present invention belongs to the technical field of building engineering materials, and particularly relates to a rapid-setting recycled concrete for emergency repair and construction and a preparation method thereof. Background Art

[0002] China's emergency repair field faces dual rigid demands: on the one hand, it is necessary to achieve rapid forming of concrete structures within 3 hours during the 72-hour golden rescue period after a disaster; on the other hand, it is urgent to break through the key bottlenecks of traditional building materials, such as low transportation efficiency (the proportion of aggregate transportation exceeds 60%) and high environmental load in areas with interrupted transportation. Especially for emergency repair scenarios such as road collapse clearance and dike piping plugging, the setting control system of existing materials (initial setting 4 - 12 hours, final setting 12 - 24 hours) seriously lags behind the time sensitivity requirements of emergency projects.

[0003] Recycled concrete is a kind of concrete material that replaces part of natural aggregate by recycling and processing waste crushed concrete, and it has good environmental friendliness. However, its performance such as setting time and strength still fails to meet the application requirements in special environments that need to be built urgently. Traditional rapid-setting concrete has extremely poor fluidity and is generally used for shotcrete. After using a rapid-setting agent, it instantly loses fluidity and can solidify on some large slope bottoms or walls. If this concrete is poured into a mold, it will instantly solidify at the pouring point and cannot flow by itself to fill the mold to complete the casting. Therefore, traditional rapid-setting concrete cannot be used for conventional projects to cast concrete according to the mold pattern.

[0004] In summary, developing a rapid-setting recycled concrete suitable for emergency repair and construction is of great practical significance for improving construction efficiency, reducing resource waste, and making full use of waste concrete resources. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a rapid-setting recycled concrete for emergency repair and construction that has a short setting time, high mechanical strength, stable chemical properties, excellent economy and environmental protection, and a preparation method thereof.

[0006] To solve the above technical problems, the present invention proposes the following technical solutions.

[0007] A preparation method of a rapid-setting recycled concrete for emergency repair and construction includes the following steps: (1) Weigh raw materials according to the following mass parts: 192 - 195 parts of water, 642 - 643 parts of cement, 98 - 99 parts of fly ash, 723 - 724 parts of natural river sand, 523 - 524 parts of recycled coarse aggregate, 3.1 - 3.2 parts of water reducing agent, 44.4 - 44.5 parts of liquid alkali-free rapid-setting agent, and 77.8 - 78.1 parts of copper-plated steel fiber; (2) Mix the cement and fly ash evenly to obtain a cementitious material; reserve a part of the water, and denote the reserved water as , then satisfies the following formula (I): Formula (I) In the formula: is the reserved water, with the unit of kg / m 3 concrete, C is the cement dosage, with the unit of kg / m 3 concrete, T is the construction temperature, with the unit of °C, 0°C ≤ T ≤ 45°C (preferably 5°C ≤ T ≤ 45°C), t is the mixing time, with the unit of s, t ≤ 3600 s; Mix the natural river sand and the cementitious material and conduct dry mixing, then add the remaining water and water reducer. The remaining water is the total water minus the reserved water, conduct primary mixing, and then add copper-plated steel fibers and recycled coarse aggregates, conduct secondary mixing, and obtain a mixture; among them, the total time of the primary mixing and the secondary mixing is t in formula (I); (3) Add a liquid alkali-free accelerator and the reserved water to the mixture , stir for 20 s to 45 s, and obtain a concrete mixture in a gel state; (4) Pour the concrete mixture in the gel state into a mold for vibration, and obtain a quick-setting type recycled concrete for emergency repair and construction after standing, demolding, and curing.

[0008] For the above preparation method of the quick-setting type recycled concrete for emergency repair and construction, preferably, in step (1), the liquid alkali-free accelerator meets the implementation standard GB / T 35159-2017, and the liquid alkali-free accelerator includes the FSA-AF type liquid alkali-free accelerator. The apparent appearance of the liquid alkali-free accelerator is a light yellow liquid with a white tint.

[0009] For the above preparation method of the quick-setting type recycled concrete for emergency repair and construction, preferably, in step (1), the copper-plated steel fibers meet the implementation standard JT / T 524-2019, the length of the copper-plated steel fibers is 12 mm to 15 mm, the diameter of the copper-plated steel fibers is 0.18 mm to 0.3 mm, and the tensile strength of the copper-plated steel fibers > 3000 MPa. The surface of the copper-plated steel fibers is smooth, and the appearance is brass-colored.

[0010] The preparation method of the rapid-setting recycled concrete for emergency repair and construction, preferably, in step (1), the recycled coarse aggregate is obtained by crushing, sieving, washing, and drying waste ordinary natural aggregate concrete, and the recycled coarse aggregate has the following characteristics: 0 < water content ≤ 0.5%, 9.7% ≤ water absorption rate ≤ 11.3%, 0 < particle size ≤ 31.5 mm; The waste ordinary natural aggregate concrete is characterized in that: the 28-day standard curing strength reaches above 50 MPa; if the components are in parts by mass, it includes 402 - 403 parts of ordinary Portland cement, 100 - 101 parts of pulverized coal ash, 729 - 730 parts of natural river sand, 1048.5 - 1050.5 parts of natural gravel, 1.0 - 1.2 parts of water reducing agent, 161 - 162 parts of water, and the water-binder ratio is 0.32.

[0011] The preparation method of the rapid-setting recycled concrete for emergency repair and construction, preferably, in step (1), the natural river sand has the following characteristics: the proportion of particle size 0.08 mm < particle size ≤ 0.16 mm is 13% ± 5%, the proportion of particle size 0.16 mm < particle size ≤ 0.5 mm is 20% ± 5%, the proportion of particle size 0.5 mm < particle size ≤ 1.00 mm is 23% ± 5%, the proportion of particle size 1 mm < particle size ≤ 1.6 mm is 33% ± 5%, and the proportion of particle size 1.6 mm < particle size ≤ 2 mm is 11% ± 5%.

[0012] The preparation method of the rapid-setting recycled concrete for emergency repair and construction, preferably, in step (1), the water reducing agent is a polycarboxylate water reducing agent, the water reducing rate of the polycarboxylate water reducing agent is 25% - 29%, the cement is ordinary Portland cement, the ordinary Portland cement includes PO42.5 ordinary Portland cement, and the fly ash is grade I fly ash. The polycarboxylate water reducing agent is white powdery particles, usually with a solid content of 99%. Grade I fly ash is in the form of spherical particles (fly ash microspheres), with a specific surface area of 1280 m 2 / kg, water demand of 98%, spherical particle density of 2.25 g / cm 3 , spherical particle content of 90%, fineness of 12%, loss on ignition of 2.34%, and strength activity index of 86%.

[0013] The preparation method of the rapid-setting recycled concrete for emergency repair and construction, preferably, in step (2), the dry mixing time is 2 min - 4 min, the first mixing time is 2 min - 4 min, and the second mixing time is 3 min - 5 min.

[0014] The preparation method of the rapid-setting recycled concrete for emergency repair and construction, preferably, in step (4), the vibration time is 30 s - 45 s, the standing time is 23 h - 24 h, and the curing time is 1 day - 3 days.

[0015] As a general technical concept, the present invention also provides a quick-setting recycled concrete for emergency repair and construction prepared by the preparation method of the above-mentioned quick-setting recycled concrete for emergency repair and construction.

[0016] In the present invention, the recycled coarse aggregate can be prepared through the following methods, but not limited to this: Manually screen the waste ordinary natural aggregate concrete (with a strength of 50 MPa or above), select good-quality solid blocks, remove impurities such as needle-like and flaky particles, wood chips, and cement mortar blocks, crush them into aggregates of different particle sizes using a jaw crusher, sieve out the aggregates using standard square-hole sieves of different particle sizes, and remove surface dust, impurities, and other surface attachments through repeated washing. After drying in the sun, the recycled coarse aggregate is obtained.

[0017] Glossary: Sand ratio: The mass percentage of natural river sand / (natural river sand + recycled coarse aggregate).

[0018] Quick-setting property: For general concrete, it may take several hours from pouring to hardening, while quick-setting concrete shortens this time. The quick-setting property represents the performance of the setting time. Compared with ordinary concrete, if it has a faster setting time, this concrete is said to have quick-setting property.

[0019] Compared with the prior art, the advantages of the present invention are as follows: (1) The present invention provides a preparation method of quick-setting recycled concrete for emergency repair and construction. By adopting a staged quantitative water control process, the concrete can not only set quickly but also obtain great fluidity in a short time, solving the problem of extremely poor fluidity of traditional quick-setting concrete. The recycled concrete of the present invention is more conducive to the construction pouring of ordinary projects compared with ordinary concrete or quick-setting concrete. The recycled concrete prepared by the present invention significantly reduces the setting time compared with existing conventional concrete, is more resource-saving, and has higher strength. The initial setting time of the recycled concrete of the present invention is within 25 minutes, and the final setting time is within 35 minutes. The strength after standard curing for 3 days can reach more than 44 MPa, making it more suitable for the requirements of quickly repairing and building damaged buildings needed for engineering construction.

[0020] Due to extremely poor fluidity, traditional quick-setting concrete is generally used for shotcrete. After using a quick-setting agent, it instantly loses fluidity and will solidify on some large slope bottoms or walls. If this concrete is poured into a mold, it will instantly solidify at the pouring point and cannot flow by itself to fill the mold to complete the casting. Therefore, it cannot be used for conventional projects to cast concrete according to the mold pattern. The quick-setting recycled concrete of the present invention adopts a staged quantitative water control process, enabling the concrete to obtain great fluidity in a short time, through the following as shown in formula (Ⅰ) V 1The reserved water formula accurately regulates fluidity, comprehensively considering variables such as the on-site construction environment temperature (construction temperature) T (°C), mixing time t (s), and different amounts of cement usage C (kg / m³). Compared with ordinary concrete or quick-setting concrete, it is more conducive to the construction pouring of conventional ordinary projects. The recycled concrete of the present invention has better construction performance compared with conventional quick-setting concrete, and its workability can be better adapted to construction.

[0021] The recycled concrete prepared by the present invention is different from the low-strength recycled concrete in the past. The recycled concrete of the present invention has excellent mechanical properties while having quick-setting properties. Due to the natural disadvantage of recycled concrete, that is, there is a relatively weak bonding area between recycled aggregates and new and old mortar, resulting in the strength of recycled concrete being inferior to that of natural aggregate concrete. However, the present invention adopts copper-plated steel fibers and a staged water control process to increase crack resistance while greatly improving the tensile strength, toughness, and early strength of the concrete. In the preparation process of the present invention, cement and fly ash are evenly mixed to obtain a cementitious material, and the subsequent addition of water enables the hydration products (ettringite, calcium hydroxide, calcium silicate, etc.) formed by the cementitious material to effectively fill the rough holes on the recycled aggregates, making the cement matrix tightly combined with the recycled coarse aggregates, with a significant increase in strength and better mechanical properties obtained.

[0022] Existing ordinary concrete fails in a severe brittle failure. The fragments broken after being impacted may cause secondary injuries to the personnel inside the building. However, the failure mode of the present invention is more excellent. After the concrete fails, it will not break apart, but will generate cracks like bulletproof glass, with significantly fewer fragments. At the same time, the fluidity brought by the staged quantitative water control process makes the concrete more dense, greatly improving the strength of its impact resistance. In the case of being subjected to a high strain rate impact load, it can ensure a good shape to the greatest extent, and even if it fails, it can greatly reduce personnel injuries, thereby protecting the personnel and equipment inside the building.

[0023] (2) To ensure the reasonable application of the reserved water formula (Ⅰ), the present invention controls the mixing time within no more than 3600 s, which can ensure that the water consumption in the first stage can fully stimulate the hydration activity of cement without destroying the designed water-cement ratio of the concrete.

[0024] (3) After adding liquid alkali-free quick-setting agent and reserved water to the mixture, the present invention controls the mixing time within 20 s to 45 s. Not less than 20 s can ensure that the concrete mixture forms a uniform cementitious state, and if it exceeds 45 s, the fluidity will be greatly reduced under the action of the quick-setting agent.

[0025] (4)The preparation technical process of the present invention can be used for the repair-type concrete that appears in the future, which has the characteristics of short setting time, fast strength growth, easy local material sourcing, and environmentally friendly and low-carbon preparation and construction. Description of the Drawings

[0026] Figure 1 SEM diagram of the rapid-setting recycled concrete for emergency repair and construction prepared in Example 1 of the present invention.

[0027] Figure 2 SEM diagram of the ordinary concrete prepared in Comparative Example 1. Detailed Embodiments

[0028] The present invention will be further described below in conjunction with the attached drawings of the specification and specific preferred embodiments, but the protection scope of the present invention is not limited thereby. The materials and instruments used in the following embodiments are all commercially available.

[0029] Example 1 A preparation method of the rapid-setting recycled concrete for emergency repair and construction of the present invention includes the following steps: (1) Weigh the raw materials according to the following parts by mass: 192 parts of water, 642.3 parts of cement, 98.46 parts of fly ash, 723 parts of natural river sand, 523.0 parts of recycled coarse aggregate, 3.1 parts of water reducer, 44.5 parts of liquid alkali-free rapid-setting agent, and 77.8 parts of copper-plated steel fiber; when 1 part by mass is 1 kg, 1 m³ of concrete is obtained; (2) Mix the cement and fly ash weighed in step (1) evenly to obtain a cementitious material; reserve a part of the water, and the reserved water is denoted as , then satisfies the following formula (Ⅰ): Formula (Ⅰ) In the formula: is the reserved water, with the unit of kg / m 3 concrete, C is the cement dosage, with the unit of kg / m 3 concrete, T is the construction temperature, with the unit of °C, 5°C ≤ T ≤ 45°C ( T can also be as low as 0°C), t is the mixing time, with the unit of s, t ≤ 3600 s; in this embodiment, the construction temperature T is 25°C and the mixing time is 300 s, then = 48.173 kg / m 3 concrete, that is, 48.173 parts; Add natural river sand and cementitious materials into the HJW-60 type mixing equipment, mix and dry mix for 3 min, then add the remaining water and water reducing agent. The remaining water is the total water ( ) minus the reserved water , mix for 2 min, then add copper-plated steel fibers and recycled coarse aggregates, mix for 3 min to obtain a mixture; (3) Add liquid alkali-free accelerating agent and the reserved water to the mixture , mix for 30 s until the concrete mixture completely becomes a uniform gel state to obtain a concrete mixture in gel state; (4) Pour the above-mentioned concrete mixture in gel state into a cube mold of 100 mm×100 mm×100 mm, vibrate for 30 s, let it stand for 24 h, then demold and cure it in a standard curing box to obtain a rapid-setting recycled concrete for emergency repair and construction. The microscopic morphology is as Figure 1 shown.

[0030] In step (1) of this embodiment: The liquid alkali-free accelerating agent meets the implementation standard GB / T 35159-2017. The liquid alkali-free accelerating agent is the FSA-AF type liquid alkali-free accelerating agent, and the brand is Niji Technology Brand, which is commercially available. The apparent appearance of this liquid alkali-free accelerating agent is a white to light yellow liquid; in this embodiment, the dosage of the liquid alkali-free accelerating agent (abbreviation: accelerating agent) is 6%; The calculation formula of the dosage is shown in formula (Ⅱ): Formula (Ⅱ) Wherein, A is the dosage of the liquid alkali-free accelerating agent, with the unit of kg / m³ of concrete, C is the cement dosage, with the unit of kg / m³ of concrete, and F is the fly ash dosage, with the unit of kg / m³ of concrete.

[0031] The copper-plated steel fibers meet the implementation standard JT / T 524-2019. The length of the copper-plated steel fibers is 12 mm to 15 mm, the diameter of the copper-plated steel fibers is 0.18 mm to 0.3 mm, the surface is smooth, the appearance is brass-colored, and the tensile strength > 3000 MPa; The water is tap water that meets the national standard; The recycled coarse aggregates are obtained by crushing, sieving, cleaning, and drying waste ordinary natural aggregate concrete. The recycled coarse aggregates have the following characteristics: 0 < water content ≤ 0.5%, 9.7% ≤ water absorption rate ≤ 11.3%, 0 < particle size ≤ 31.5 mm.

[0032] The characteristics of the discarded ordinary natural aggregate concrete are as follows: the standard curing strength at 28 days is 50 - 55 MPa; or, its composition by mass includes 402.3 parts of ordinary Portland cement, 100.58 parts of fly ash, 723 parts of natural river sand, 1049 parts of natural crushed stone, 1.1 parts of water reducing agent, and 161.3 parts of water, and the water - binder ratio is 0.32, but not limited to this; The natural river sand is natural salvaged river sand, and the natural river sand has the following characteristics: 0.08 mm < particle size ≤ 2 mm, among which the proportion of natural river sand with a particle size of 0.08 mm - 0.16 mm is 13% ± 5%, the proportion of 0.16 mm - 0.5 mm is 20% ± 5%, the proportion of 0.5 mm - 1.00 mm is 23% ± 5%, the proportion of 1 mm - 1.6 mm is 33% ± 5%, and the proportion of 1.6 mm - 2 mm is 11% ± 5%.

[0033] The water reducing agent is a polycarboxylate water reducing agent, which is white powdery particles, the solid content is 99%, and the water reducing rate of the polycarboxylate water reducing agent is 25% - 28%; The cement is ordinary Portland cement, and the ordinary Portland cement is PO42.5 ordinary Portland cement; The fly ash is Class I fly ash.

[0034] In step (4) of this embodiment, when curing for 3 days, 7 days, and the standard age of 28 days, a part of the specimens is taken for compressive strength test, and the results are shown in Table 1.

[0035] Comparative Example 1 A kind of ordinary concrete, the difference in the preparation process of this concrete from that of Example 1 is as follows: 1. Replace the recycled coarse aggregate with natural gravel coarse aggregate; 2. Add all the water in step (2) instead of adding it in two times; 3. Do not add liquid alkali - free accelerating agent and copper - plated steel fiber; 4. The mix ratio is different from that of Example 1, that is, 161 parts of water, 402 parts of ordinary Portland cement, 100 parts of pulverized coal ash, 729 parts of natural river sand, 1049.0 parts of natural gravel coarse aggregate, 1.0 part of water reducing agent, and the water - binder ratio is 0.32. The microscopic morphology of this ordinary concrete is as Figure 2 shown.

[0036] consisting of Figure 1 and Figure 2It can be seen that from a microscopic perspective, there is an obvious transition zone between the cement mortar matrix and the aggregate in ordinary concrete, while the recycled aggregate concrete of the present invention can tightly combine the cement mortar matrix with the aggregate, showing more excellent macroscopic properties. Compared with ordinary concrete, the recycled aggregate concrete of the present invention has better impact mechanical properties because copper-plated steel fibers are incorporated, and at the same time, a staged quantitative water control process is adopted to improve its setting time while ensuring its compactness performance. After the cement is cured, a mechanical biting force is formed with the copper-plated steel fibers, causing the copper-plated steel fibers to be tightly embedded in the cement mortar, increasing the ductility and tensile capacity of the concrete during destruction.

[0037] Comparative Example 2 A preparation method of recycled aggregate concrete, the preparation process is basically the same as that of Example 1, the only difference being: the staged quantitative water control process is not adopted, and all the water is added in step (2). Due to the non-adoption of this process, after adding the accelerating agent, the mixture instantly loses its fluidity, completely loses its fluidity, loses the ability to pour into the mold, and there are phenomena such as many internal cavities and exposed aggregates, and the 28d standard compressive strength only reaches 81.2% of that of Example 1.

[0038] Comparative Example 3 A preparation method of rapid-setting recycled aggregate concrete, the preparation process is basically the same as that of Example 1, the only difference being: copper-plated steel fibers are not added. When the content of copper-plated steel fibers is reduced by 100% relative to (Example 1), the strengths at 3, 7, and 28d are reduced by 20%, 12.4%, and 5.3% respectively. Because the copper-plated steel fibers in Example 1 form a mechanical biting force, causing the copper-plated steel fibers to be tightly embedded in the cement mortar, increasing the ductility and tensile capacity of the concrete during destruction.

[0039] Example 2

[0040] A preparation method of rapid-setting recycled concrete for emergency repair and construction of the present invention, which is basically the same as Example 1, the only difference being: the dosage of the accelerating agent is 7%. Example 3

[0041] A preparation method of rapid-setting recycled concrete for emergency repair and construction of the present invention, which is basically the same as Example 1, the only difference being: the dosage of the accelerating agent is 8%.

[0042] As can be seen from Table 1, the 3-day strength of the rapid-setting recycled concrete of the present invention can reach 71% of the 28d compressive strength, showing a certain early strength property. As can be seen from Table 1 and Table 2, the rapid-setting recycled concrete of the present invention has good early strength performance and excellent setting performance, and can be applied to the actual projects of emergency repair and construction.

[0043] The quick-setting recycled concrete prepared in this embodiment for emergency repair and construction also has good workability, meeting the technical requirements of the project for concrete. Combining Table 1 and Table 2, on the premise of meeting the setting time within minutes, it can reach a strength grade of 60 MPa, which is a significant decrease compared to the setting time of ordinary concrete for several hours. Moreover, the construction process is simple and easy to implement, and it can meet the requirements for high-strength concrete in civil concrete projects.

[0044] The above is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the above-disclosed methods and technical contents, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A preparation method of a quick-setting recycled concrete for emergency repair and construction, characterized in that, It includes the following steps: (1) Weigh raw materials according to the following parts by mass: 192 - 195 parts of water, 642 - 643 parts of cement, 98 - 99 parts of fly ash, 723 - 724 parts of natural river sand, 523 - 524 parts of recycled coarse aggregate, 3.1 - 3.2 parts of water reducer, 44.4 - 44.5 parts of liquid alkali-free accelerating agent, and 77.8 - 78.1 parts of copper-plated steel fiber; (2) Mix cement and fly ash evenly to obtain a cementitious material; reserve a portion of the water, and denote the reserved water as , then satisfies the following formula (I): Formula (I) Where: is the reserved water, in kg / m 3 concrete, C is the cement dosage, in kg / m 3 concrete, T is the construction temperature, in °C, 0°C ≤ T ≤ 45°C, t is the mixing time, in s, t ≤ 3600 s; Mix the natural river sand and the cementitious materials and perform dry mixing, then add the remaining water and the water reducer. The remaining water is the total water minus the reserved water, perform primary mixing, then add the copper-plated steel fiber and the recycled coarse aggregate, and perform secondary mixing to obtain a mixture; where the total time of the primary mixing and the secondary mixing is t in formula (Ⅰ); (3) Add liquid alkali-free accelerator and the reserved water to the mixture , stir for 20s to 45s to obtain a concrete mixture in a gel state; (4) Put the concrete mixture in the gel state into a mold for vibration, and after standing, demolding, and curing, obtain a quick-setting recycled concrete for emergency repair and construction.

2. The preparation method of the quick-setting recycled concrete for emergency repair and construction according to claim 1, characterized in that, In step (1), the liquid alkali-free accelerating agent meets the implementation standard GB / T 35159 - 2017, and the liquid alkali-free accelerating agent includes FSA-AF type liquid alkali-free accelerating agent.

3. The preparation method of the quick-setting recycled concrete for emergency repair and construction according to claim 1, characterized in that, In step (1), the copper-plated steel fiber meets the implementation standard JT / T 524 - 2019, the length of the copper-plated steel fiber is 12 - 15 mm, the diameter of the copper-plated steel fiber is 0.18 - 0.3 mm, and the tensile strength of the copper-plated steel fiber > 3000 MPa.

4. The preparation method of the rapid-setting recycled concrete for emergency repair and construction according to any one of claims 1 to 3, characterized in that, In step (1), the recycled coarse aggregate is prepared by crushing, sieving, cleaning, and drying waste ordinary natural aggregate concrete, and the recycled coarse aggregate has the following characteristics: 0 < water content ≤ 0.5%, 9.7% ≤ water absorption rate ≤ 11.3%, 0 < particle size ≤ 31.5 mm; The characteristics of the waste ordinary natural aggregate concrete are: the 28-day standard curing strength reaches above 50 MPa.

5. The preparation method of the quick-setting recycled concrete for emergency repair and construction according to any one of claims 1 to 3, characterized in that, In step (1), the natural river sand has the following characteristics: The proportion of particle size 0.08 mm < particle size ≤ 0.16 mm is 13% ± 5%, the proportion of particle size 0.16 mm < particle size ≤ 0.5 mm is 20% ± 5%, the proportion of particle size 0.5 mm < particle size ≤ 1.00 mm is 23% ± 5%, the proportion of particle size 1 mm < particle size ≤ 1.6 mm is 33% ± 5%, and the proportion of particle size 1.6 mm < particle size ≤ 2 mm is 11% ± 5%.

6. The preparation method of the quick-setting recycled concrete for emergency repair and construction according to any one of claims 1 to 3, characterized in that In step (1), the water reducer is a polycarboxylate water reducer, the water reduction rate of the polycarboxylate water reducer is 25% - 29%, the cement is ordinary Portland cement, the ordinary Portland cement includes PO42.5 ordinary Portland cement, and the fly ash is grade Ⅰ fly ash.

7. The preparation method of the quick-setting recycled concrete for emergency repair and construction according to any one of claims 1 to 3, characterized in that In step (2), the time of dry mixing is 2 - 4 min, the time of primary mixing is 2 - 4 min, and the time of secondary mixing is 3 - 5 min.

8. The preparation method of the rapid-setting recycled concrete for emergency repair and construction according to any one of claims 1 to 3, characterized in that, In step (4), the time of vibration is 30 s - 45 s, the time of standing is 23 h - 24 h, and the time of curing is 1 - 3 days.

9. A rapid-setting recycled concrete for emergency repair and construction prepared by the method for preparing rapid-setting recycled concrete for emergency repair and construction according to any one of claims 1 to 8.

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