Multi-dimensional hybrid cast-in-place fiber concrete with controllable fiber content and preparation method thereof

Abstract

A multi-dimensional hybrid infiltration fiber concrete with controllable fiber content belongs to the field of building material concrete and is composed of the following components by mass: 20-40 parts of double-fast cement, 20-40 parts of fine aggregate, 5-10 parts of ultrafine silica microbeads, 10-25 parts of waste tire steel fiber, 3-10 parts of three-dimensional spiral steel fiber, 0.2-0.4 parts of water reducer, 0.1-0.3 parts of interfacial activator, 0.05-0.1 parts of thixotropic agent, and 4-8 parts of water. A preparation method for multi-dimensional hybrid infiltration fiber concrete with controllable fiber content is also provided. The present invention uses one-dimensional waste tire steel fiber and three-dimensional spiral steel fiber for multi-dimensional mixing. By optimizing the fiber content and spatial distribution, the mechanical properties of the material are improved. At the same time, without relying on special manufacturing molds or additional construction auxiliary control, the production cost and construction difficulty are greatly reduced, making it more economical and engineering applicable.

Description

Technical Field

[0001] The invention belongs to the field of concrete, and in particular relates to a cast-in-place fiber concrete with controllable fiber content based on waste tire steel fibers and three-dimensional spiral fibers, and a preparation method thereof. Background Art

[0002] Cast-in-place fiber reinforced concrete is formed by injecting a fluid mortar into a mold containing a pre-placed steel fiber skeleton. The steel fiber volume fraction can reach up to 25%. Cast-in-place fiber reinforced concrete offers significantly improved mechanical properties compared to conventional concrete. Its tensile strength is on the same order of magnitude as the compressive strength of conventional concrete, and its energy absorption capacity is three orders of magnitude greater than that of conventional concrete.

[0003] Currently, the steel fibers used in cast-in-place concrete primarily include ordinary carbon steel fibers, stainless steel fibers, and the more expensive copper-coated fine steel fibers. Ordinary carbon steel fibers are widely used in general fiber-reinforced concrete due to their low cost, but their durability and corrosion resistance are relatively poor. Stainless steel fibers offer good corrosion resistance and high strength, but their high price limits their application in large-scale projects. Copper-coated fine steel fibers are typically used in ultra-high-performance concrete (UHPC) or specialized structures. The copper coating on their surface enhances the bond between the fiber and the matrix, but the high material cost increases the overall project cost. However, the relatively fixed bulk density of steel fibers makes it difficult to flexibly adjust the fiber dosage, making it difficult to precisely control the fiber distribution during construction. Furthermore, high dosages not only reduce the permeability of the slurry and affect the uniformity of the matrix, but also significantly increase material costs, limiting the widespread application of cast-in-place concrete in engineering projects.

[0004] With the continuous development of the automobile industry, a large amount of waste tires are generated every year. In the prior art, these waste tires are usually treated in simple ways such as open-air stacking or direct incineration. These methods not only occupy a large amount of land resources, but also cause serious environmental pollution and increase resource waste. How to efficiently recycle and rationally utilize the steel fibers in waste tires has become an important direction for promoting the development of green building materials. The steel fibers obtained by peeling and screening from waste tires still have high tensile strength. During the separation process, the fiber shape undergoes spatial distortion, which improves its anchoring force and the accumulation effect in the matrix. The rubber remaining on the fiber surface can further enhance the interfacial bonding between the fiber and the matrix, and improve the energy absorption capacity of the material. Based on this, the present invention uses recycled waste tire steel fibers to prepare cast-in-place concrete with high cost performance and good construction adaptability, while reducing production costs and improving the comprehensive performance of the material.

[0005] In order to overcome the performance limitations of traditional steel fibers in cast-in-place concrete, some inventions use specially made three-dimensional fibers to optimize the spatial distribution of fibers. For example, Chinese patent CN 113754332 A discloses a three-dimensional steel fiber, and Chinese patent CN 113636771 B discloses an arc-shaped steel fiber. Although these fibers can form a more stable reinforcement structure in concrete, their production relies on specific manufacturing molds, resulting in high manufacturing costs and complex processes, making it difficult to achieve large-scale engineering applications. In addition, Chinese patent CN119462025A proposes a fiber spatial arrangement technology based on electromagnetic field directional control. Although this method can achieve directional arrangement of fibers, its production process is cumbersome and the construction equipment requirements are high, which greatly increases the difficulty and cost of engineering implementation. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology, the present invention provides a multi-dimensional hybrid infiltration fiber concrete with controllable fiber content and a preparation method thereof. The total amount of steel fiber filling is controlled by the spatial characteristics of the three-dimensional spiral steel fibers, and a specially prepared high-strength and high-fluidity mortar is injected into a mold in which a steel fiber skeleton is previously placed to prepare the infiltration fiber concrete. Concrete with both excellent mechanical properties and crack resistance can be prepared. The preparation method involved is simple and low-cost, can realize the utilization of waste tire steel fibers and the effective control of the total amount of fibers, and has important economic, social and environmental benefits.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] A multi-dimensional hybrid infiltration fiber concrete with controllable fiber content is composed of the following components in parts by mass: 20-40 parts of double-fast cement, 20-40 parts of fine aggregate, 5-10 parts of ultrafine silica microbeads, 10-25 parts of waste tire steel fiber, 3-10 parts of three-dimensional spiral steel fiber, 0.2-0.4 parts of water reducer, 0.1-0.3 parts of interfacial activator, 0.05-0.1 parts of thixotropic agent and 4-8 parts of water.

[0009] Furthermore, the double-fast cement uses tricalcium silicate and calcium fluoroaluminate as main raw materials, has a setting time of no more than 0.5 hours, and a strength of no less than 60 MPa.

[0010] Furthermore, the recycled fine aggregate is an aggregate with a particle size less than 0.6 mm and greater than 0.075 mm, and its material is silicon dioxide.

[0011] Furthermore, the specific surface area of ​​the ultrafine silica microbeads is not less than 300 m2 / kg, and the particle size distribution is 0.2 to 2 μm.

[0012] The waste tire steel fiber is a steel wire for rubber tire rims or tire edge steel wire, with a diameter of 0.2mm to 2mm, a length of 2mm to 30mm, and a tensile strength of not less than 1500MPa.

[0013] The fiber filament diameter of the three-dimensional spiral steel fiber is 0.1mm to 0.3mm, the outer diameter of the spiral steel fiber is 4mm to 20mm, and the length is 5mm to 40mm.

[0014] The water reducing agent is a polycarboxylic acid type water reducing agent with a water reduction rate of not less than 30%.

[0015] The interfacial activator is one of ethanolamine, diethanolamine, triethanolamine, triisopropanolamine or diethanol monoisopropanolamine, or a mixture of two or more thereof.

[0016] The thixotropic agent is nano silicon dioxide, and the particle size thereof is 30nm to 50nm.

[0017] A method for preparing multi-dimensional hybrid cast-in-place fiber concrete with controllable fiber content, wherein the method uses multi-dimensional hybrid steel fibers as a main toughening material and is prepared by cast-in-place high-strength, high-fluidity double-fast cement mortar, and the method comprises the following steps:

[0018] Step 1: Mix the two fibers evenly and spread them throughout the entire mold. Utilize the spatial characteristics of the three-dimensional spiral steel fibers to form a three-dimensional spatial network structure. The volume content of the mixed fibers is controlled at 2% to 12%.

[0019] Step 2: Prepare the infiltration mortar according to the following proportions: per cubic meter of mortar, based on 100 parts by weight, the mortar is composed of the following components in parts by mass: 20-40 parts of double-fast cement, 20-40 parts of fine aggregate, 5-10 parts of ultrafine silica microbeads, 10-25 parts of waste tire steel fiber, 3-10 parts of three-dimensional spiral steel fiber, 0.2-0.4 parts of water reducer, 0.1-0.3 parts of interfacial activator, 0.05-0.1 parts of thixotropic agent, and 4-8 parts of water;

[0020] Step 3: Pour the double-fast cement, ultrafine silica microbeads, water reducer, and thixotropic agent into a mixer according to the weight of the formula and dry mix them evenly for 2-3 minutes. Then, add fine aggregate and interfacial activator and stir for 2-3 minutes. Then, pour water and stir for 5-6 minutes to obtain double-fast cement mortar slurry;

[0021] Step 4: Slowly inject the mortar slurry obtained in step 3 into the mold filled with mixed fibers until the slurry is slightly higher than the mold surface, and then place the mold in an environment with a temperature of 20±5°C and let it stand for one to two days and nights, then number it and remove the mold; after removing the mold, immediately place it in a standard curing room with a temperature of 20±2°C and a relative humidity of more than 95% for curing for more than 28 days to obtain the infiltration mixed steel fiber concrete.

[0022] The technical concept of the present invention is to use one-dimensional waste tire steel fibers and three-dimensional spiral steel fibers for multi-dimensional mixing, and improve the mechanical properties of the material by optimizing the fiber dosage and spatial distribution. At the same time, the present invention does not require special manufacturing molds or additional construction auxiliary controls, which greatly reduces production costs and construction difficulty, making it more economical and engineering applicable.

[0023] First, the present invention uses steel fibers extracted from waste tires, achieving high-value recycling of waste materials. This not only effectively reduces environmental pollution, but also, with the help of the rubber particles remaining on the surface of the waste tire steel fibers, improves the interfacial adhesion between the fibers and the matrix, thereby enhancing the overall mechanical properties of the concrete, with significant economic, environmental, and social benefits. Secondly, the three-dimensional spiral steel fibers used in the present invention, due to their unique "spiral" spatial structure, form a mechanical interlocking effect with the cement matrix, significantly improving the interfacial bonding strength, delaying crack propagation, and improving the fracture toughness of the material. At the same time, the three-dimensional spiral steel fibers have a relatively complex geometric shape, and their three-dimensional spiral structure has significant spatial advantages, which can achieve a high volume filling rate with an extremely low fiber content. Traditional cast-in-place fiber concrete mostly uses a single long straight fiber as the filling skeleton. Due to its constant packing density, the fiber content of this type cannot be adjusted, and the small pores between the fibers often make it difficult to fill the slurry densely. To address the above problems, the present invention utilizes the spatial structural characteristics of the three-dimensional spiral fibers and mixes them with traditional long straight fibers for filling, which can effectively control the volume content of the long straight fibers, thereby obtaining a cast-in-place fiber concrete material with adjustable fiber content. Compared to traditional cast-in-place steel fiber concrete (SIFCON), which requires a fiber volume fraction of more than 10% to achieve a good reinforcement effect, the present invention uses a multi-dimensional hybrid reinforcement strategy to ensure excellent tensile, impact, and crack resistance at a lower dosage (≤ 4%), reducing material usage and improving economic efficiency. In addition, during the preparation of traditional cast-in-place steel fiber concrete, steel fibers are often placed in a mold in advance. The volumetric dosage of steel fibers is difficult to calculate accurately, and external vibrations can easily cause the steel fibers to sink and the mortar to have difficulty in penetrating. The spiral fiber concrete used in the present invention has a cylindrical shape, which facilitates the calculation of the filling volume. In addition, the hollow cavity within the spiral fiber facilitates the rapid filling of the cast-in-place mortar. Finally, the infiltration mortar of the present invention adopts an interfacial activator and a thixotropic agent, which not only greatly improves the interfacial bonding force between the fiber and the slurry, and increases the energy consumption of fiber pull-out during destruction, but also significantly enhances the rheological properties of the mortar and the void passing performance during pouring, thereby improving the density and construction convenience of the infiltration fiber concrete, so that it can be widely used in rapid reinforcement and emergency repair projects, showing excellent compressive, bending, and shear properties as well as excellent ductility and toughness.

[0024] The present invention breaks through the limitations of traditional cast-in-place fiber concrete by rationally configuring one-dimensional and three-dimensional fibers, and provides a new material solution with high strength, high toughness and low cost for the project.

[0025] The beneficial effects of the present invention are mainly manifested in:

[0026] 1. This invention uses ultra-high fluidity, rapid-hardening cement mortar and leverages the dimensional stability of three-dimensional spiral steel fibers to reduce fiber accumulation, allowing the slurry to more evenly and fully penetrate the steel fiber skeleton, thereby improving the permeability and uniformity of the slurry and ensuring the overall stability of the concrete performance.

[0027] 2. Compared with traditional SIFCON, which requires a high dosage of more than 10% by volume, the multi-dimensional hybrid design of the present invention can ensure good tensile, impact and crack resistance at a lower dosage (≤ 4%).

[0028] 3. The present invention makes full use of recycled waste tire steel fibers, which have a much lower cost than copper-plated steel fibers or special three-dimensional steel fibers. In addition, their distorted shape and rough surface help to improve the interfacial adhesion of the matrix. While maintaining excellent material performance, they have a higher cost-effectiveness and are suitable for large-scale engineering applications.

[0029] 4. The spatial bridging effect of the three-dimensional spiral steel fiber of the present invention can effectively disperse stress, inhibit crack expansion, and improve the energy absorption capacity of concrete. It is suitable for scenes with high toughness requirements such as bridges, tunnels, and earthquake-resistant projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the direct tensile stress-strain curve of the multi-dimensional hybrid cast-infiltration fiber concrete of the present invention.

[0031] Figure 2 This is a four-point bending load-displacement curve of the multi-dimensional hybrid cast-in-place fiber concrete of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below.

[0033] Reference Figure 1 and Figure 2 A multi-dimensional hybrid infiltration fiber concrete with controllable fiber content is composed of the following components in parts by mass: 20-40 parts of double-fast cement, 20-40 parts of fine aggregate, 5-10 parts of ultrafine silica microbeads, 10-25 parts of waste tire steel fiber, 3-10 parts of three-dimensional spiral steel fiber, 0.2-0.4 parts of water reducer, 0.1-0.3 parts of interfacial activator, 0.05-0.1 parts of thixotropic agent and 4-8 parts of water.

[0034] The double-fast cement is primarily made from tricalcium silicate and calcium fluoroaluminate, has a setting time of no more than 0.5 hours, and a strength of no less than 60 MPa. The recycled fine aggregate is silica aggregate with a particle size of less than 0.6 mm and greater than 0.075 mm. The ultrafine silica microbeads have a specific surface area of ​​no less than 300 m² / kg, with a particle size distribution of 0.2 to 2 μm. The scrap tire steel fiber is rubber tire bead wire or tire edge wire, with a diameter of 0.2 to 2 mm, a length of 2 to 30 mm, and a tensile strength of no less than 1500 MPa. The three-dimensional spiral steel fiber has a fiber strand diameter of 0.1 to 0.3 mm, an outer diameter of 4 to 20 mm, and a length of 5 to 40 mm. The water reducer is a polycarboxylic acid-based water reducer with a water reduction rate of no less than 30%. The interfacial activator is one or more of ethanolamine, diethanolamine, triethanolamine, triisopropanolamine or diethanol monoisopropanolamine. The thixotropic agent is nano-silicon dioxide with a particle size of 30nm to 50nm.

[0035] The double-fast cement used in the following embodiments is high-belite sulphoaluminate cement; the fine aggregate used is 20-40 mesh fine sand; the particle size of the ultrafine silica microbeads used is in the range of 50 μm-100 μm; the water reducer used is MELFLUX4930F polymer water reducer; the activator used is ultrafine slag powder; and the thixotropic agent used is ATTGEL50 thixotropic agent.

[0036] Example 1

[0037] A multi-dimensional hybrid fiber concrete with controllable fiber content. The raw materials used include, by mass, 30 parts of double-fast cement, 30 parts of fine aggregate, 8 parts of ultrafine silica beads, 10 parts of waste tire steel fiber, 9 parts of three-dimensional spiral steel fiber, 0.3 parts of water reducer, 0.3 parts of activator, 0.1 parts of thixotropic agent and 6 parts of water. In this embodiment, the fiber volume content is approximately 3.8%.

[0038] A method for preparing multi-dimensional hybrid cast-in-place fiber concrete with controllable fiber content comprises the following steps:

[0039] Step 1: Mix the two fibers evenly and spread them throughout the entire mold. Utilize the spatial characteristics of the three-dimensional spiral steel fibers to form a three-dimensional network structure. The volume content of the mixed fibers is controlled at 3.8%.

[0040] According to the test or engineering requirements, place the mold in the pouring area and ensure that the mold is well sealed. Spread the three-dimensional spiral steel fibers evenly on the bottom of the formwork according to the set dosage to form a mesh skeleton. Since the spiral steel fibers have self-supporting capabilities, they can naturally form a multi-dimensional support structure after laying, providing a certain bearing capacity to avoid excessive fiber accumulation or collapse. Evenly spread one-dimensional steel fibers with a preset dosage above the skeleton of the three-dimensional spiral steel fibers. Since the three-dimensional spiral steel fibers provide support, the one-dimensional steel fibers can be suspended to avoid direct contact with the bottom of the formwork, thereby improving the uniformity of their spatial distribution in the matrix. Through slight shaking or low-speed airflow assistance, the one-dimensional steel fibers are dispersed under the support of the three-dimensional spiral steel fibers, thereby improving the bridging effect between the fibers and avoiding local excessive accumulation;

[0041] Step 2: Prepare the infiltration mortar according to the following proportions: per cubic meter of mortar, based on 100 parts by weight, the mortar is composed of the following components in parts by mass: 30 parts of double-fast cement, 30 parts of fine aggregate, 8 parts of ultrafine silica microbeads, 10 parts of waste tire steel fiber, 9 parts of three-dimensional spiral steel fiber, 0.3 parts of water reducer, 0.3 parts of activator, 0.1 parts of thixotropic agent and 6 parts of water;

[0042] Step 3: Pour the double-fast cement, ultrafine silica microbeads, water reducer, and thixotropic agent into a mixer according to the weight of the formula and dry-mix and stir evenly for 2 minutes. Then, add fine aggregate and interfacial activator and stir for 2 minutes. Then, pour water and stir for 5 minutes to obtain double-fast cement mortar slurry;

[0043] The process of step three is as follows:

[0044] S1. According to the weight ratio of the formula, double-fast cement, ultrafine silica microbeads, water reducer, and thixotropic agent are poured into a mixer and dry-mixed and stirred evenly. The stirring time is not less than 2 minutes at a speed of 40r / min, and then fine aggregate and interfacial activator are added and stirred for 2 minutes to obtain a dry mix;

[0045] S2. Stir the dry mix with water for 5 minutes to mix evenly to obtain a high-fluidity double-fast cement mortar slurry.

[0046] Step 4: Slowly inject the mortar slurry obtained in step 3 into the mold filled with mixed fibers until the slurry is slightly higher than the mold surface, and then place the mold in an environment with a temperature of 20°C and let it stand for a day and a night, then number it and remove the mold; after removing the mold, immediately place it in a standard curing room with a temperature of 20°C and a relative humidity of more than 95% for curing for more than 28 days to obtain infiltration mixed steel fiber concrete.

[0047] Using a layered pouring method, ultra-high-flow cement mortar is slowly poured into the fiber space skeleton to ensure that the mortar fully wraps the fibers and avoids flow obstruction caused by fiber accumulation. Low-frequency vibration is used to remove bubbles within the mortar, improve the density of the concrete, and reduce porosity.

[0048] The curing process is as follows:

[0049] S1. Curing in a dry curing room at a temperature of 20℃ for one day and night, then removing the mold;

[0050] S2. Move the test piece to a standard curing room with a temperature of 20°C and a humidity of not less than 95% and cure for more than 28 days.

[0051] Then the mechanical properties were tested: the tensile and flexural properties of the multi-dimensional hybrid infiltration fiber concrete were tested after 28 days.

[0052] Example 2

[0053] A multi-dimensional hybrid fiber concrete with controllable fiber content. The raw materials used include, by mass, 30 parts of double-fast cement, 30 parts of fine aggregate, 8 parts of ultrafine silica beads, 22 parts of waste tire steel fiber, 3 parts of three-dimensional spiral steel fiber, 0.3 parts of water reducer, 0.3 parts of activator, 0.1 parts of thixotropic agent and 6 parts of water. In this example, the fiber volume content is approximately 8.2%.

[0054] A method for preparing multi-dimensional hybrid cast-in-place fiber concrete with controllable fiber content comprises the following steps:

[0055] Step 1: Mix the two fibers evenly and spread them throughout the entire mold. Utilize the spatial characteristics of the three-dimensional spiral steel fibers to form a three-dimensional spatial network structure. The volume content of the mixed fibers is controlled at 8.2%.

[0056] According to the test or engineering requirements, place the mold in the pouring area and ensure that the mold is well sealed. Spread the three-dimensional spiral steel fibers evenly on the bottom of the formwork according to the set dosage to form a mesh skeleton. Since the spiral steel fibers have self-supporting capabilities, they can naturally form a multi-dimensional support structure after laying, providing a certain bearing capacity to avoid excessive fiber accumulation or collapse. Evenly spread one-dimensional steel fibers with a preset dosage above the skeleton of the three-dimensional spiral steel fibers. Since the three-dimensional spiral steel fibers provide support, the one-dimensional steel fibers can be suspended to avoid direct contact with the bottom of the formwork, thereby improving the uniformity of their spatial distribution in the matrix. Through slight shaking or low-speed airflow assistance, the one-dimensional steel fibers are dispersed under the support of the three-dimensional spiral steel fibers, thereby improving the bridging effect between the fibers and avoiding local excessive accumulation;

[0057] Step 2: Prepare the infiltration mortar according to the following ratio. Each cubic meter of mortar, based on 100 parts by weight, consists of the following components in parts by mass: 30 parts of double-fast cement, 30 parts of fine aggregate, 8 parts of ultrafine silica microbeads, 22 parts of waste tire steel fiber, 3 parts of three-dimensional spiral steel fiber, 0.3 parts of water reducer, 0.3 parts of activator, 0.1 parts of thixotropic agent and 6 parts of water.

[0058] In step three of this embodiment, stirring for 2.5 minutes, then adding fine aggregate and interfacial activator and stirring for 2.5 minutes, then pouring water and stirring for 5.5 minutes to obtain a double-fast cement mortar slurry;

[0059] In step 4 of this embodiment, the mold is placed in an environment with a temperature of 15°C and allowed to stand for 1.5 days and then numbered and demolded; immediately after demolding, it is placed in a standard curing room with a temperature of 15°C and a relative humidity of more than 95% for curing for more than 28 days.

[0060] The remaining steps are the same as in Example 1. Figure 1 and Figure 2 The tensile and flexural test data for Examples 1 and 2 are shown. A comparative analysis of the two sets of examples shows that in Example 1, although the three-dimensional spiral steel fiber content is only slightly higher than in Example 2 and the one-dimensional fiber content is significantly reduced, its overall mechanical properties do not show a significant decline, and it still maintains excellent ductility. This demonstrates that while optimizing the spatial distribution of fibers, the three-dimensional spiral steel fibers can effectively regulate the fiber content, maintaining good mechanical properties even when the one-dimensional fiber content is reduced. This result further validates the key role of three-dimensional spiral steel fibers in improving fiber utilization efficiency and optimizing material reinforcement mechanisms.

[0061] Example 3

[0062] A multi-dimensional hybrid fiber concrete with controllable fiber content. The raw materials used include, by mass, 20 parts of double-fast cement, 20 parts of fine aggregate, 5 parts of ultrafine silica beads, 15 parts of waste tire steel fiber, 6 parts of three-dimensional spiral steel fiber, 0.2 parts of water reducer, 0.1 parts of activator, 0.05 parts of thixotropic agent and 4 parts of water. In this example, the fiber volume content is approximately 5.9%.

[0063] Except for the different formula, the preparation method of this embodiment is the same as that of Example 1.

[0064] In step three of this embodiment, stirring for 3 minutes, then adding fine aggregate and interfacial activator and stirring for 3 minutes, then pouring water and stirring for 6 minutes to obtain a double-fast cement mortar slurry;

[0065] In step 4 of this embodiment, the mold is placed in an environment with a temperature of 25°C and allowed to stand for two days and nights, then numbered and demolded; immediately after demolding, it is placed in a standard curing room with a temperature of 25°C and a relative humidity of more than 95% for curing for more than 28 days.

[0066] Example 4

[0067] A multi-dimensional hybrid fiber concrete with controllable fiber content. The raw materials used include, by mass, 40 parts of double-fast cement, 40 parts of fine aggregate, 10 parts of ultrafine silica microbeads, 25 parts of waste tire steel fiber, 10 parts of three-dimensional spiral steel fiber, 0.4 parts of water reducer, 0.2 parts of activator, 0.08 parts of thixotropic agent and 8 parts of water. In this example, the fiber volume content is approximately 4.8%.

[0068] Except for the different formula, the preparation method of this embodiment is the same as that of Example 1.

[0069] In step three of this embodiment, stirring for 3 minutes, then adding fine aggregate and interfacial activator and stirring for 2 minutes, then pouring water and stirring for 6 minutes to obtain a double-fast cement mortar slurry;

[0070] In step 4 of this embodiment, the mold is placed in an environment with a temperature of 22°C and allowed to stand for two days and nights, then numbered and demolded; immediately after demolding, it is placed in a standard curing room with a temperature of 24°C and a relative humidity of more than 95% for curing for more than 28 days.

[0071] The embodiments of this specification are merely examples of implementations of the invention and are provided for illustrative purposes only. The scope of protection of the present invention should not be considered limited to the specific embodiments described in these embodiments. The scope of protection of the present invention also extends to equivalent technical means that can be conceived by a person of ordinary skill in the art based on the invention.

Claims

1. A multi-dimensional hybrid fiber concrete with controllable fiber content, characterized in that: It is composed of the following components in parts by mass: 20-40 parts of double-fast cement, 20-40 parts of fine aggregate, 5-10 parts of ultrafine silica microbeads, 10-25 parts of waste tire steel fiber, 3-10 parts of three-dimensional spiral steel fiber, 0.2-0.4 parts of water reducer, 0.1-0.3 parts of interfacial activator, 0.05-0.1 parts of thixotropic agent and 4-8 parts of water.

2. The multi-dimensional hybrid fiber concrete with controllable fiber content according to claim 1, characterized in that: The double-fast cement uses tricalcium silicate and calcium fluoroaluminate as main raw materials, has a setting time of no more than 0.5 hours, and a strength of no less than 60 MPa.

3. The multi-dimensional hybrid cast-in-place fiber concrete with controllable fiber content according to claim 1 or 2, characterized in that: The fine aggregate is an aggregate with a particle size less than 0.6 mm and greater than 0.075 mm, and its material is silicon dioxide.

4. The multi-dimensional hybrid cast-in-place fiber concrete with controllable fiber content according to claim 1 or 2, characterized in that: The specific surface area of ​​the ultrafine silica microbeads is not less than 300m2 / kg, and the particle size distribution is 0.2 to 2μm.

5. The multi-dimensional hybrid cast-in-place fiber concrete with controllable fiber content according to claim 1 or 2, characterized in that: The waste tire steel fiber is a steel wire for rubber tire rims or tire edge steel wire, with a diameter of 0.2mm to 2mm, a length of 2mm to 30mm, and a tensile strength of not less than 1500MPa.

6. The multi-dimensional hybrid cast-in-place fiber concrete with controllable fiber content according to claim 1 or 2, characterized in that: The fiber filament diameter of the three-dimensional spiral steel fiber is 0.1mm to 0.3mm, the outer diameter of the spiral steel fiber is 4mm to 20mm, and the length is 5mm to 40mm.

7. The multi-dimensional hybrid fiber concrete with controllable fiber content according to claim 1 or 2, characterized in that: The water reducing agent is a polycarboxylic acid type water reducing agent with a water reduction rate of not less than 30%.

8. The multi-dimensional hybrid cast-in-place fiber concrete with controllable fiber content according to claim 1 or 2, characterized in that: The interfacial activator is one of ethanolamine, diethanolamine, triethanolamine, triisopropanolamine or diethanol monoisopropanolamine, or a mixture of two or more thereof.

9. The multi-dimensional hybrid cast-in-place fiber concrete with controllable fiber content according to claim 1 or 2, characterized in that: The thixotropic agent is nano silicon dioxide, and the particle size thereof is 30nm to 50nm.

10. A method for preparing multi-dimensional hybrid fiber concrete with controllable fiber content as claimed in claim 1, characterized in that: The method comprises the following steps: Step 1: Mix the two fibers evenly and spread them throughout the entire mold. Utilize the spatial characteristics of the three-dimensional spiral steel fibers to form a three-dimensional spatial network structure. The volume content of the mixed fibers is controlled at 2% to 12%. Step 2: Prepare the infiltration mortar according to the following proportions: per cubic meter of mortar, based on 100 parts by weight, the mortar is composed of the following components in parts by mass: 20-40 parts of double-fast cement, 20-40 parts of fine aggregate, 5-10 parts of ultrafine silica microbeads, 10-25 parts of waste tire steel fiber, 3-10 parts of three-dimensional spiral steel fiber, 0.2-0.4 parts of water reducer, 0.1-0.3 parts of interfacial activator, 0.05-0.1 parts of thixotropic agent, and 4-8 parts of water; Step 3: Pour the double-fast cement, ultrafine silica microbeads, water reducer, and thixotropic agent into a mixer according to the weight of the formula and dry mix them evenly for 2-3 minutes. Then, add fine aggregate and interfacial activator and stir for 2-3 minutes. Then, pour water and stir for 5-6 minutes to obtain double-fast cement mortar slurry; Step 4: Slowly inject the mortar slurry obtained in step 3 into the mold filled with mixed fibers until the slurry is slightly higher than the mold surface, and then place the mold in an environment with a temperature of 20±5°C and let it stand for one to two days and nights, then number it and remove the mold; after removing the mold, immediately place it in a standard curing room with a temperature of 20±2°C and a relative humidity of more than 95% for curing for more than 28 days to obtain the infiltration mixed steel fiber concrete.

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