Double-liquid type 3D printing steel fiber concrete and preparation method thereof

Abstract

The invention provides double-liquid type 3D printing steel fiber concrete and a preparation method thereof.The concrete comprises a component A and a component B. The component A comprises fly ash, silica fume, steel fibers, a viscosity modifier, quartz sand, a water reducing agent and water; the component A comprises an interface binder, a coagulant, an internal curing agent and water; the component A is a basic gelling system of the concrete, and the component B is a reinforcing phase for promoting solidification; through a double-liquid reaction synergistic mechanism of the component A and the component B, the adaptability of keeping fluidity during printing and quickly curing after printing of the concrete is realized; a'flexible adhesive film-fiber bridging 'dual reinforcement structure exists in a basic gel system, so that the interlayer bonding strength is improved, and generation and expansion of interlayer cracks are inhibited; the breaking strength and the fracture toughness of the material are greatly improved, and the brittle fracture defect of traditional 3D printing concrete is fundamentally improved.

Description

Technical Field

[0001] This application belongs to the field of building 3D printing materials technology, and particularly relates to a two-liquid 3D printing steel fiber concrete and its preparation method. Background Technology

[0002] In the process of 3D printing concrete construction, traditional printing materials face three major challenges: First, the printing process needs to balance fluidity and plasticity. Traditional single-liquid materials are prone to insufficient fluidity leading to pipe blockage, or excessive fluidity causing the printed parts to collapse and deform. Second, the interlayer interface is weak, and it is easy to generate interlayer cracks due to material shrinkage and environmental humidity, which reduces the overall load-bearing capacity of the structure. Third, the material has poor toughness and weak impact resistance, and is prone to brittle fracture under external force, making it difficult to meet the requirements of dynamic loads or scenarios with high crack resistance.

[0003] Currently, mainstream 3D printed concrete is mainly single-component type. Although the preparation process is simple, the setting time is difficult to control, and no reinforcing phase is introduced, resulting in prominent toughness defects. Even when fibers are added, glass fibers and polypropylene fibers are mostly used, which have weaker tensile strength and interfacial bonding force than steel fibers, resulting in limited reinforcement effect. In addition, existing fiber-containing printing materials often cause pipe blockage due to poor fiber dispersion, or improper fiber content affects fluidity, making it difficult to balance "printing smoothness" and "reinforcing effect".

[0004] Therefore, developing a two-component 3D-printed concrete that incorporates a reinforcing phase, combines fluidity and plasticity, has high interlayer bond strength, excellent toughness, and controllable setting time is of great significance for promoting the large-scale application of 3D-printed building technology. Summary of the Invention

[0005] This application provides a two-component 3D printed steel fiber reinforced concrete and its preparation method to solve the problems existing in related technologies. The technical solution is as follows: In a first aspect, embodiments of this application provide a two-component 3D printed steel fiber concrete, comprising component A and component B; component A and component B are mixed and used in a volume ratio of (8-12):1. Component A comprises the following components in parts by weight: 70-80 parts silicate cement; 15-25 parts fly ash; 3-7 parts silica fume; 2-4 parts steel fiber; 0.1-0.3 parts viscosity modifier; 80-100 parts quartz sand; 0.1-0.3 parts water-reducing agent; 20-40 parts water; Component B comprises the following components in parts by weight: Interface binder 0.5-2 parts; coagulant accelerator 15-25 parts; internal curing agent 0.1-1 parts; water 90-110 parts.

[0006] In one embodiment, the silicate cement is P·II 52.5R silicate cement.

[0007] In one embodiment, the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent.

[0008] In one embodiment, the steel fiber is a hook-shaped cold-drawn steel wire fiber.

[0009] In one embodiment, the fly ash is Class F, Grade I fly ash.

[0010] In one embodiment, the viscosity modifier is hydroxypropyl methylcellulose ether.

[0011] In one embodiment, the steel fiber has a length of 10-12 mm and a diameter of 0.2 mm.

[0012] In one embodiment, the fly ash has a water requirement ratio of ≤95% and a loss on ignition of ≤5%.

[0013] In one embodiment, the specific surface area of ​​the silica fume is ≥15000 m². 2 / kg, SiO2 content ≥90%.

[0014] In one embodiment, the quartz sand is continuously graded quartz sand with a particle size of 0.15-0.6 mm and a mud content of ≤1%.

[0015] In one embodiment, the viscosity of the viscosity modifier is ≥100,000 mPa·s.

[0016] In one embodiment, the interface adhesive is one or more of the following: polyethylene-vinyl acetate copolymer emulsion, acrylate emulsion, styrene-butadiene latex, and epoxy resin emulsion.

[0017] In one embodiment, the coagulant is one or more of sodium silicate, lithium carbonate, calcium formate, and nano-CSH.

[0018] In one embodiment, the internal curing agent is sodium polyacrylate.

[0019] Secondly, embodiments of this application provide a method for preparing 3D-printed steel fiber reinforced concrete, comprising the following steps: Preparation of Component A slurry: Silicate cement, fly ash, silica fume, quartz sand, thickener and water-reducing agent are mixed evenly; steel fibers are slowly added and stirred at high speed; Add the water in batches according to the formula, stirring after each addition, until a uniform, lump-free, and fiber-free A component slurry is formed; Preparation of Component B slurry: Water, interfacial binder and quick-setting agent are stirred evenly; internal curing agent is added and stirring is continued to be evenly mixed to obtain Component B slurry; Using a 3D printing mechanism, the slurry of component B and component A are transported and mixed according to the pumping speed of component A slurry : component B slurry (8-12):1, and then the 3D printing operation is performed.

[0020] In one embodiment, after the A component slurry is prepared, it is continuously stirred and stored at a temperature of 15-30°C for no more than 30 minutes. Once the B component slurry is prepared, it should be used within 20 minutes.

[0021] The advantages or beneficial effects of the above technical solutions include at least the following: The concrete of this application comprises component A and component B. Component A is the basic cementitious system of the concrete, and component B is a reinforcing phase that promotes setting and curing. Through the synergistic mechanism of the two-liquid reaction of components A and B, the concrete achieves the adaptability of "maintaining fluidity during printing and rapid curing after printing". Furthermore, the basic cementitious system has a dual reinforcing structure of "flexible adhesive film-fiber bridging", which not only improves the interlayer bond strength, but also inhibits the generation and propagation of interlayer cracks. The flexural strength and fracture toughness of the material are greatly improved, fundamentally improving the brittle fracture defects of traditional 3D printed concrete.

[0022] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of this application will become readily apparent from the following detailed description. Detailed Implementation

[0023] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the description is considered to be exemplary in nature and not restrictive.

[0024] In a first aspect, embodiments of this application provide a two-component 3D printed steel fiber concrete, comprising component A and component B; component A and component B are mixed and used in a volume ratio of (8-12):1. Component A comprises the following components in parts by weight: 70-80 parts silicate cement; 15-25 parts fly ash; 3-7 parts silica fume; 2-4 parts steel fiber; 0.1-0.3 parts viscosity modifier; 80-100 parts quartz sand; 0.1-0.3 parts water-reducing agent; 20-40 parts water; Component B comprises the following components in parts by weight: Interface binder 0.5-2 parts; coagulant accelerator 15-25 parts; internal curing agent 0.1-1 parts; water 90-110 parts.

[0025] This application utilizes a two-liquid reaction synergistic mechanism. After component A and component B are mixed, the coagulant in component B rapidly activates the hydration of the cementitious material, generating a large amount of high-strength hydration products such as hydrated calcium silicate and hydrated calcium sulfoaluminate, achieving the adaptability of "maintaining fluidity during printing and rapid curing after printing." Component A itself also possesses an interlayer reinforcement and fiber synergistic mechanism. The interlayer bonding enhancer in component A forms a flexible adhesive film at the interface of the printed layer, filling the interfacial micropores and alleviating shrinkage stress.

[0026] As one embodiment, the silicate cement is P·II 52.5R silicate cement.

[0027] As one embodiment, the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent.

[0028] In one embodiment, the steel fiber is a hook-shaped cold-drawn steel wire fiber. More preferably, the steel fiber has a length of 10-12 mm and a diameter of 0.2 mm.

[0029] Steel fibers bridge adjacent printed layers, constructing a dual-reinforcement structure of "flexible adhesive film-fiber bridging," which not only improves interlayer bonding strength but also inhibits the generation and propagation of interlayer cracks. Furthermore, the steel fibers in component A achieve a toughness optimization mechanism through "crack bridging and stress dispersion," preventing the further development of microcracks within the printed concrete, significantly improving the material's flexural strength and fracture toughness, and fundamentally improving the brittle fracture defects of traditional 3D printed concrete.

[0030] As one embodiment, the fly ash is Class F Grade I fly ash; more preferably, the fly ash has a water requirement ratio ≤95% and a loss on ignition ≤5%.

[0031] In one embodiment, the viscosity modifier is hydroxypropyl methylcellulose ether. More preferably, the viscosity of the hydroxypropyl methylcellulose ether is ≥100,000 mPa·s.

[0032] As one embodiment, the silica fume has a specific surface area ≥15000m². 2 / kg, SiO2 content ≥90%.

[0033] In one embodiment, the quartz sand is continuously graded quartz sand with a particle size of 0.15-0.6 mm and a mud content of ≤1%.

[0034] As one embodiment, the interface adhesive is one or more of the following: polyethylene-vinyl acetate copolymer emulsion, acrylate emulsion, styrene-butadiene latex, and epoxy resin emulsion.

[0035] In one embodiment, the accelerator is a combination of one or more of sodium silicate, lithium carbonate, calcium formate, and nano-CSH. The accelerator rapidly activates the hydration of the cementitious material, generating a large amount of high-strength hydration products such as hydrated calcium silicate and hydrated calcium sulfoaluminate, achieving the adaptability of "maintaining fluidity during printing and rapid curing after printing".

[0036] As one embodiment, the internal curing agent is sodium polyacrylate.

[0037] This application also provides a method for preparing 3D printed steel fiber reinforced concrete, comprising the following steps: Preparation of Component A slurry: Silicate cement, fly ash, silica fume, quartz sand, thickener and water-reducing agent are mixed evenly; steel fibers are slowly added and stirred at high speed; Add the water in batches according to the formula, stirring after each addition, until a uniform, lump-free, and fiber-free A component slurry is formed; Preparation of Component B slurry: Water, interface binder and quick-setting agent are stirred evenly; internal curing agent is added and stirring is continued to be evenly mixed to obtain Component B slurry; Using a 3D printing mechanism, with the pumping speed of component A slurry being (8-12):1, component B slurry is evenly applied to the surface of the concrete strip formed by printing component A slurry.

[0038] In this embodiment, the preparation of component A slurry is carried out in a mixer. The formulated amounts of silicate cement, fly ash, silica fume, quartz sand, thickener, and water-reducing agent are added to the mixer and stirred; generally, the stirring time is 2-3 minutes. Then, steel fibers are slowly added to the mixture and stirred at high speed for 4-6 minutes. Then, the formulated amounts of water are added in batches and stirred; preferably, the water is added in 2-3 batches; preferably, stirring for 3-4 minutes after each addition of water; stirring continues until a uniform, lump-free, and fiber-free component A slurry is formed.

[0039] In this embodiment, the prepared A component slurry is transferred into a storage tank with a stirring function, continuously stirred, and the storage temperature is strictly controlled at 15-30℃, with a storage time not exceeding 30 minutes.

[0040] In this embodiment, the preparation of component B slurry is carried out in a mixer. Specifically, mixing water, interfacial binder, and accelerator are added sequentially to the mixer and stirred until homogeneous; preferably, the stirring time is 3-4 minutes. Then, an internal curing agent is added and stirring continues; the stirring time is 1-2 minutes. In this embodiment, the prepared component B slurry is transferred to a storage tank. The preparation of component B slurry should follow the principle of small-batch, multiple-time preparation and be completed within 20 minutes.

[0041] In this embodiment, component A slurry and component B slurry are mixed and printed using a 3D printing mechanism. During use, the component B slurry and component A slurry are transported and mixed at a pump speed of (8-12):1, and then the 3D printing operation is performed. A specific implementation method will be further explained below.

[0042] Example 1 A two-component 3D-printed steel fiber reinforced concrete, wherein the volume ratio of component A to component B is 10:1, and the composition by weight is as follows: Component A slurry: 75 parts silicate cement; 20 parts fly ash; 5 parts silica fume; 3 parts steel fiber; 0.2 parts viscosity modifier; 90 parts quartz sand; 0.2 parts water-reducing agent; 30 parts water; Component B slurry: 1 part interface binder; 20 parts coagulant; 0.5 parts internal curing agent; 100 parts water The silicate cement is P·II 52.5R silicate cement; The fly ash mentioned is Class F, Grade I fly ash, with a water requirement ratio ≤95% and a loss on ignition ≤5%; The silica fume has a specific surface area ≥15000m² 2 / kg, SiO2 content ≥90%; The steel fiber is a hook-shaped cold-drawn steel wire fiber with a length of 10-12mm and a diameter of 0.2mm; The viscosity modifier is hydroxypropyl methylcellulose ether with a viscosity ≥ 100,000 mPa·s.

[0043] The quartz sand is a continuously graded quartz sand with a particle size of 0.15-0.6 mm and a mud content of ≤1%.

[0044] The water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent.

[0045] The interface binder is a polyethylene-vinyl acetate copolymer emulsion.

[0046] The coagulant is a mixture of sodium silicate and lithium carbonate in a mass ratio of 10:3. The internal curing agent is sodium polyacrylate; The preparation method includes the following steps: Add silicate cement, fly ash, silica fume, quartz sand, thickener, and water-reducing agent to the A component slurry preparation mixer and stir for 2-3 minutes; slowly add steel fibers and stir at high speed for 4-6 minutes; add the prescribed amount of water in 2-3 batches, stirring for 3-4 minutes after each addition, until a uniform A component slurry without lumps or obvious fiber agglomeration is formed; transfer the prepared A component slurry to a storage tank with a stirring function, continue stirring, and strictly control the storage temperature at 15-30℃ for no more than 30 minutes; Add mixing water, interface binder and quick-setting agent to the mixer for preparing component B slurry in sequence, and stir for 3-4 minutes; add internal curing agent and stir for 1 minute; transfer the prepared component B slurry to the storage tank; the preparation of component B slurry should follow the principle of small amount and multiple times, and be used within 20 minutes; The A component slurry storage tank and the B component slurry storage tank are connected to the top of the 3D printing mixing nozzle through different metering pumps. The slurry is delivered at a ratio of 10:1 (A component slurry pump speed: B component slurry pump speed). At the same time, the 3D printing mixing nozzle is started to perform the printing operation. Example 2 The difference from Example 1 is that: the steel fiber content in component A slurry is 2 parts; and the interfacial binder content in component B slurry is 0.5 parts. Other components and preparation methods are the same as in Example 1.

[0047] Example 3 The difference from Example 1 is that: the steel fiber content in component A slurry is 4 parts; and the coagulant content in component B slurry is 15 parts. Other components and preparation methods are the same as in Example 1.

[0048] Example 4 The difference from Example 1 is that: the A component slurry contains 15 parts fly ash and 7 parts silica fume; the B component slurry contains 0.1 parts internal curing agent. Other components and preparation methods are the same as in Example 1.

[0049] Example 5 The difference from Example 1 is that: the A component slurry contains 25 parts fly ash and 3 parts silica fume; the B component slurry contains 1 part internal curing agent. Other components and preparation methods are the same as in Example 1.

[0050] Example 6 The difference from Example 1 is that: the quartz sand in component A slurry is 80 parts; and the coagulant in component B slurry is 25 parts. Other components and preparation methods are the same as in Example 1.

[0051] Example 7 The difference from Example 1 is that: the quartz sand in component A slurry is 100 parts; and the interfacial binder in component B slurry is 2 parts. Other components and preparation methods are the same as in Example 1.

[0052] Example 8 The difference from Example 1 is that: the silicate cement in component A slurry is 70 parts; the accelerator in component B slurry is a mixture of sodium silicate and lithium carbonate (mass ratio 1:1). Other components and preparation methods are the same as in Example 1.

[0053] Example 9 The difference from Example 1 is that: the silicate cement in component A slurry is 80 parts; and the interfacial binder in component B slurry is an acrylic emulsion. Other components and preparation methods are the same as in Example 1.

[0054] Example 10 The difference from Example 1 is that the water-reducing agent in component A slurry is 0.1 parts; and the coagulant accelerator in component B slurry is nano-CSH. Other components and preparation methods are the same as in Example 1.

[0055] Comparative Example 1 The difference from Example 1 is that the steel fiber content in component A slurry is 0 parts. Other components and preparation methods are the same as in Example 1.

[0056] Comparative Example 2 The difference from Example 1 is that the viscosity modifier in component A slurry is 0 parts. Other components and preparation methods are the same as in Example 1.

[0057] Comparative Example 3 The difference from Example 1 is that the interfacial binder in component B slurry is 0 parts. Other components and preparation methods are the same as in Example 1.

[0058] Comparative Example 4 The difference from Example 1 is that the coagulant in component B slurry is 0 parts. Other components and preparation methods are the same as in Example 1.

[0059] Comparative Example 5 The difference from Example 1 is that the internal curing agent in component B slurry is 0 parts. Other components and preparation methods are the same as in Example 1.

[0060] Comparative Example 6 The difference from Example 1 is that the steel fibers in component A slurry are 3 parts polypropylene fibers (10 mm in length and 0.2 mm in diameter). Other components and preparation methods are the same as in Example 1.

[0061] Comparative Example 7 The difference from Example 1 is that component B slurry was not used. Other components and preparation methods are the same as in Example 1.

[0062] Performance testing: The performance of the two-component 3D-printed steel fiber reinforced concrete prepared in Examples 1-10 and Comparative Examples 1-7 was tested, including interlayer bond strength, 28-day flexural strength, 28-day compressive strength, and initial setting time. The test methods are as follows: Interlayer bond strength testing: The interlayer shear test method was used. Interlayer bond test blocks with dimensions of 100mm × 100mm × 100mm were prepared using a 3D printer according to actual printing parameters. During printing, the printing interval between adjacent layers was controlled to match the actual engineering process, ensuring that the interlayer interface of the test block simulated the real printing state. After the test blocks were cured to the specified age (28 days), shear loading was applied using a universal testing machine at a speed controlled at 0.5mm / min until interlayer failure occurred, and the maximum failure load was recorded. The interlayer bond strength was calculated using the formula τ = F / A, where τ is the interlayer bond strength (MPa), F is the maximum failure load (N), and A is the interlayer bond stress area (mm²). 2 The results are shown in Table 1.

[0063] 28-day flexural strength test: The three-point bending test method was used. Prismatic specimens of 100mm × 100mm × 400mm were prepared using a 3D printer according to the specimen size requirements of the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The printing direction was consistent with the direction of flexural stress. After preparation, the specimens were cured in a standard curing environment (temperature 20±2℃, relative humidity ≥95%) for 28 days. After curing, a flexural strength testing machine was used. The support span was set to 300mm, and the loading speed was controlled at 0.05mm / s. The maximum load at which the specimen broke was recorded. The 28-day flexural strength was calculated using the formula f = FL / (bh). 2 The calculations were performed, where f is the flexural strength (MPa), F is the maximum failure load (N), L is the support span (mm), b is the width of the specimen section (mm), and h is the height of the specimen section (mm); the results are shown in Table 1.

[0064] 28-day compressive strength test: A cubic compressive strength test method was used. 100mm × 100mm × 100mm cubic specimens were prepared using a 3D printer, ensuring dimensional accuracy and avoiding interlayer defects during printing. After curing in a standard environment (temperature 20±2℃, relative humidity ≥95%) for 28 days, the specimens were removed, their surface moisture wiped dry, and placed in the center of the pressure plate of the compression testing machine, ensuring complete contact between the pressure-bearing surface and the pressure plate. A uniform loading method was used, with the loading speed controlled at 0.5-1.0 MPa / s, until the specimen failed, and the maximum failure load was recorded. The 28-day compressive strength was calculated using the formula f = F / A, where f is the compressive strength (MPa), F is the maximum failure load (N), and A is the pressure-bearing area of ​​the specimen (mm²). 2 The results are shown in Table 1.

[0065] Initial setting time test: The penetration resistance method was used. After the A and B components of the two-component 3D-printed steel fiber reinforced concrete were mixed evenly according to the design ratio, the mixture was immediately poured into a 150mm diameter, 150mm high mold, the surface was smoothed, and the mold was placed in a standard curing environment (temperature 20±2℃, relative humidity ≥95%) for static curing. Timing began from the moment water was added (or components were mixed), and the penetration resistance value was measured at regular intervals using a concrete penetration resistance meter. During the test, a suitable penetration needle was selected (100mm was used during the initial setting stage). 2 Insert the penetration needle evenly and slowly into the sample to a depth of 25 mm, and record the penetration resistance value and the corresponding test time. When the penetration resistance value reaches 3.5 MPa, the corresponding time is the initial setting time.

[0066] The test results are shown in Table 1.

[0067] Table 1

[0068] As can be seen from the data in Table 1, Examples 1-10 all exhibited excellent interlayer bond strength (≥3.5MPa), flexural strength (≥6.5MPa), and compressive strength (≥40MPa), with initial setting time controlled at 3-6 min and flowability retention time at 1-3 min, meeting the requirements of 3D printing.

[0069] Comparative Example 1 (without steel fiber) showed a significant decrease in interlaminar bond strength and flexural strength, indicating the key role of steel fiber in toughness and interlaminar reinforcement.

[0070] Comparative Example 2 (without viscosity modifier) ​​had excessive fluidity after printing, making it impossible to prepare a printed block for testing.

[0071] Comparative Example 3 (without interfacial adhesive) showed a significant decrease in interlayer bond strength, verifying the importance of interfacial adhesive for interlayer bonding.

[0072] Comparative Example 4 (without accelerator) had an excessively long initial setting time, and the printed parts could not be cured quickly, making it impossible to prepare printed blocks for testing.

[0073] The bonding strength of Comparative Example 5 (without internal curing agent) decreased significantly, confirming the important role of internal curing agent in the formation of interfacial adhesives.

[0074] Comparative Example 6 (using polypropylene fiber as a substitute) showed a significant decrease in bond strength, flexural strength, and compressive strength, indicating that steel fiber can better improve the performance of 3D printed concrete than polypropylene fiber.

[0075] Comparative Example 7 (slurry of component A only) had excessive fluidity after extrusion and an extremely long setting time, making it impossible to prepare printed blocks for testing.

[0076] The above comparisons confirm that the absence or substitution of any key component will lead to the failure or performance degradation of 3D printed concrete.

[0077] In summary, the two-component 3D printed steel fiber concrete of this invention achieves a balance between fluidity and setting speed through the synergistic effect of component A and component B slurry, resulting in high interlayer bond strength and excellent toughness.

[0078] In summary, this application utilizes a two-component synergistic approach with component A and component B slurry to print concrete. Initial setting occurs within 3-10 minutes after mixing, with the fluidity retention time adjustable to 1-3 minutes as needed. The steel fibers are uniformly dispersed without the risk of pipe blockage, ensuring a smooth printing process and preventing collapse and deformation of the printed parts due to slow curing. The interlayer bond strength of the printed concrete is ≥3.5MPa, and the 28-day flexural strength is ≥6.5MPa, effectively addressing the two core issues of interlayer weakness and brittle fracture. Furthermore, the printed body exhibits stable mechanical properties, with a 28-day compressive strength reaching 40MPa, meeting the load-bearing requirements of most building structures. The minimal dispersion in mechanical properties ensures the stability of the printed component's quality.

[0079] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0080] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0081] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A two-component 3D-printed steel fiber reinforced concrete, characterized in that, Includes component A and component B; component A and component B are mixed and used in a volume ratio of (8-12):1; Component A comprises the following components in parts by weight: 70-80 parts silicate cement; 15-25 parts fly ash; 3-7 parts silica fume; 2-4 parts steel fiber; 0.1-0.3 parts viscosity modifier; 80-100 parts quartz sand; 0.1-0.3 parts water-reducing agent; 20-40 parts water; Component B comprises the following components in parts by weight: Interface binder 0.5-2 parts; coagulant accelerator 15-25 parts; internal curing agent 0.1-1 parts; water 90-110 parts.

2. The dual-liquid 3D printed steel fiber reinforced concrete according to claim 1, characterized in that, The silicate cement is P·II 52.5R silicate cement; the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent.

3. The dual-liquid 3D printed steel fiber reinforced concrete according to claim 1, characterized in that, The steel fiber is a hook-shaped cold-drawn steel wire fiber; the length of the steel fiber is 10-12mm and the diameter is 0.2mm.

4. The dual-liquid 3D printed steel fiber reinforced concrete according to claim 1, characterized in that, The fly ash is Class F, Grade I fly ash; the water requirement of the fly ash is ≤95%, and the loss on ignition is ≤5%.

5. The dual-liquid 3D printed steel fiber reinforced concrete according to claim 1, characterized in that, The silica fume has a specific surface area ≥15000m² 2 / kg, SiO2 content ≥90%.

6. The dual-liquid 3D printed steel fiber reinforced concrete according to claim 1, characterized in that, The quartz sand is a continuously graded quartz sand with a particle size of 0.15-0.6 mm and a mud content of ≤1%.

7. The dual-liquid 3D printed steel fiber reinforced concrete according to claim 1 or 2, characterized in that, The viscosity modifier is hydroxypropyl methylcellulose ether; viscosity ≥ 100,000 mPa·s.

8. The dual-liquid 3D printed steel fiber reinforced concrete according to claim 1, characterized in that, The interface adhesive is one or more of the following: polyethylene-vinyl acetate copolymer emulsion, acrylic emulsion, styrene-butadiene latex, and epoxy resin emulsion. The coagulant is one or more of sodium silicate, lithium carbonate, calcium formate, and nano-CSH. The internal curing agent is sodium polyacrylate.

9. The method for preparing 3D-printed steel fiber reinforced concrete according to any one of claims 1-8, characterized in that, Includes the following steps: Preparation of Component A slurry: Silicate cement, fly ash, silica fume, quartz sand, thickener and water-reducing agent are mixed evenly; steel fibers are slowly added and stirred at high speed; Add the water in batches according to the formula, stirring after each addition, until a uniform, lump-free, and fiber-free A component slurry is formed. Preparation of Component B slurry: Water, interface binder and quick-setting agent are stirred evenly; internal curing agent is added and stirring is continued to be evenly mixed to obtain Component B slurry; Using a 3D printing mechanism, the slurry of component B and component A are transported and mixed according to the pumping speed of component A slurry : component B slurry (8-12):1, and then the 3D printing operation is performed.

10. The method for preparing 3D-printed steel fiber reinforced concrete according to claim 9, characterized in that, After the slurry of component A is prepared, it is continuously stirred and stored at a temperature of 15-30℃ for no more than 30 minutes. Once the B component slurry is prepared, it should be used within 20 minutes.

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