A 3D printed reinforced concrete precast composite slab and its production process

Abstract

The present invention belongs to the field of concrete, and specifically relates to a 3D printed reinforced concrete prefabricated composite board and its production process. The production process is: clean the mold table and position it on the mold table surface; set up the steel mesh according to the positioning result, and print the frame of the composite board on the set up steel mesh through a 3D concrete printer; through the vibration of the mold table, the 3D printed concrete fills the gap under the steel bar; after the frame hardens, pour concrete on the inside of the frame; and rest, roughen, maintain, demould and avoid roughening in sequence. The production process described in the present invention has a small number of printing layers of the frame, and can be operated on a continuous mold table at the same time, which synergistically improves production efficiency; and can fill the excess gaps through small vibrations, so that the structure of the prefabricated composite board frame is tighter and firmer; and the fixation of the magnetic clamp prevents the frame from slipping during the concrete pouring and vibration process, improves product quality, and the process is correspondingly economical.

Description

Technical Field

[0001] The present invention belongs to the field of concrete, and particularly relates to a 3D printed reinforced concrete precast composite slab and its production process. Background Art

[0002] In recent years, China has vigorously developed prefabricated buildings, and the composite floor slab among them is a horizontal component used in prefabricated buildings. At present, reinforced concrete composite slabs are the most widely used composite floor slabs. Reinforced concrete composite slabs are usually prefabricated in factories, involving many processes for the frame and a large amount of manual labor. At the same time, for reinforced concrete composite slabs with special shapes, customized steel side forms are required, resulting in low efficiency and high costs. And in order to reduce special-shaped composite slabs, designers will use a large number of small composite slabs in special structural parts, thereby further reducing production efficiency and increasing production costs.

[0003] Concrete 3D printing technology is a new type of concrete construction technology developed in recent years, which can be used for the manufacture of small houses, concrete components, etc. However, the most difficult problem to solve in concrete 3D printing technology is the reinforcement problem. For example, CN208870180 U relates to a 3D printed reinforced concrete component. By 3D printing the outer shell of the concrete component, the steel reinforcement cage is completely inside the component, and ordinary concrete is poured inside at the same time, but the steel mesh cannot pass through the printing layer. Another example is CN 115146369A, which relates to a method for constructing a 3D printed precast composite floor slab. First, the outer formwork is printed to the height of the steel mesh, and then the steel mesh is erected. In actual production, there will be the following problems: First, the heights of the steel mesh in the X and Y directions are inconsistent; second, the thickness of the steel reinforcement protection layer of the reinforced concrete composite slab is 15 mm, and for a 60 mm composite slab, 4 layers need to be printed, resulting in low production efficiency; third, the printing is not continuous. After the first layer is printed, the steel mesh is erected, and then the remaining three layers are printed, with a complex process; fourth, it is suitable for fixed mold production and not suitable for assembly line production.

[0004] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a 3D printed reinforced concrete precast composite slab and its production process. In the production process, the steel mesh is erected first, and then the concrete frame is continuously 3D printed at one time, and the number of printing layers of the frame is small. At the same time, it can operate on a continuous mold table, synergistically improving production efficiency; on the other hand, during the production process, small vibrations can be used and the thixotropy of the concrete can be utilized to fill the excess gaps, making the structure of the precast composite slab more compact and firm.

[0006] The solution of the present invention is to provide a production process for a 3D printed reinforced concrete precast composite slab, and the production process includes the following steps:

[0007] (1) Clean the formwork and position it on the surface of the formwork.

[0008] (2) Erect the steel mesh according to the positioning result, and print the border of the composite slab on the erected steel mesh by a 3D concrete printer.

[0009] (3) Through slight vibration of the formwork, make the 3D printed concrete further fill the gap under the steel bars.

[0010] (4) After the border hardens, pour concrete inside the border.

[0011] (5) Cure, roughen, maintain, demold and avoid surface cleaning in sequence, then the 3D printed reinforced concrete precast composite slab is obtained.

[0012] Preferably, in step (1), clean the formwork and carry out scribing positioning or projection positioning on the surface of the formwork.

[0013] Preferably, in step (2), according to the positioning result, erect the steel mesh by using a padding method to meet the requirement of the protective layer thickness of the composite slab.

[0014] Preferably, in step (3), after the erection is completed, carry out 2-3 layers of continuous 3D reinforced concrete printing on the border of the steel mesh. After the printing is completed, make the formwork vibrate slightly. For a movable formwork, generate slight vibration by walking or a small vibrator, and for a fixed formwork, generate slight vibration by a small vibrator, so that the reinforced concrete fills the gap.

[0015] Preferably, in step (4), after the border hardens, install magnetic suction clamps on the border and the steel mesh to prevent the border from slipping during the concrete pouring and vibrating process.

[0016] Preferably, in step (5), the demolding means directly lifting the composite slab to disconnect it from the bottom formwork.

[0017] Preferably, in step (5), the so-called avoiding surface cleaning means using coarse sand or fine stone aggregate for the printed concrete material to increase the surface roughness of the printed material and avoid the edge surface cleaning step in the production of conventional composite slabs.

[0018] Another solution of the present invention is to provide a 3D printed reinforced concrete precast composite slab prepared by the above production process.

[0019] The beneficial effects of the present invention are:

[0020] The production process described in the present invention first sets up a steel bar mesh, and then continuously 3D prints the concrete frame. The number of printing layers of the frame is small, and it can be operated on a continuous die table, which synergistically improves the production efficiency. At the same time, during the production process, small vibrations can be used and the thixotropy of the concrete can be utilized to fill the excess gaps, making the structure of the precast composite slab frame more compact and firm. Before the concrete pouring, a magnetic chuck is used to fix the printed frame and the steel bar mesh to prevent the frame from slipping during the concrete pouring and vibration process, improving the product quality. In addition, compared with the traditional composite slab production process, the step of roughening the surface is eliminated, saving water and materials and reducing the sewage discharge in the factory area. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It is a schematic structural diagram of the steel bar mesh described in the present invention.

[0023] Figure 2 It is an actual diagram of the process of 3D printing reinforced concrete in the present invention.

[0024] Figure 3 It is a schematic structural diagram of the first layer of 3D printed reinforced concrete in the present invention.

[0025] Figure 4 It is a schematic structural diagram of the second layer of 3D printed reinforced concrete in the present invention.

[0026] The reference numerals in the drawings are as follows:

[0027] 1 - transverse steel bar; 2 - longitudinal steel bar; 3 - steel bar mesh; 4 - concrete; 5 - printing head; 6 - gap; 7 - cover thickness; 8 - first layer printing thickness; 9 - second layer printing thickness. Detailed Embodiments

[0028] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other implementation manners obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present invention.

[0029] Embodiment 1

[0030] This embodiment provides a production process for 3D printing reinforced concrete precast composite slabs, and the production process includes the following steps:

[0031] (1) Arrange multiple transverse steel bars 1 parallel to each other in sequence, and also arrange multiple longitudinal steel bars 2 parallel to each other in sequence, keeping the transverse steel bars 1 perpendicular to the longitudinal steel bars 2, thereby fabricating a steel bar mesh 3, which is used as the precast composite slab skeleton. Refer to Figure 1 ;

[0032] (2) Clean the mold table and conduct scribing and positioning on the surface of the mold table;

[0033] (3) According to the positioning result, use the method of adding cushion blocks to erect the steel bar mesh 3, which can also ensure the thickness of the protective layer of the reinforced concrete precast composite slab. After erection, print the first layer of concrete 4 (refer to Figure 2 ); among them, the border of the first-layer printed concrete 4 is slightly higher than the steel bars, and the discharge amount of the concrete 4 should be large, and the concrete 4 is extruded by the print head 5 to make the concrete 4 fill the space below the steel bars; in addition, due to the thixotropy of the concrete 4, there will be a gap 6 below the steel bars during natural filling (refer to Figure 3 ). For the assembly line mold table, small-amplitude vibration is increased during the movement of the mold table for filling; in addition, large-grained sand or fine gravel is used for printing the concrete, which can improve the surface roughness of the printing material and eliminate the subsequent border scabbing process;

[0034] (4) For the mold table of the assembly line operation, the printed steel bar mesh 3 waits for the border to harden through the transition station, and then magnetic positioning clamps are installed on the outside of the border to prevent slippage during the concrete pouring and vibration process. Then, truss steel bars and embedded pipelines are installed, and pouring, static curing, roughening, curing, and demolding are carried out in sequence to obtain the 3D printed reinforced concrete precast composite slab.

[0035] It should be emphasized that for comparison with the prior art, in this embodiment, the designed thickness of the reinforced concrete precast composite slab is 60 mm, the diameter of the steel bars is 8 mm, the thickness of the protective layer 7 is 15 mm, and it is printed in two layers. The printing thickness 8 of the first layer is 32 mm (15 mm + 8 mm × 2 + 1 mm allowance, refer to Figure 4 ); the printing thickness 9 of the second layer is 29 mm (refer to Figure 4 ), and the discharge amount is reduced. The total printing height is 61 mm. In order to fill the gap, small-amplitude vibration is applied to the mold table, so the border height will be reduced by about 1 mm, and the total height is reduced to about 60 mm, meeting the design expectation. While waiting for the border to harden, truss steel bars are installed, and then subsequent processes are carried out. Therefore, when the thickness of the precast slab is 60 mm, the solution of this embodiment is to print continuously twice, while the prior art requires four prints, and the efficiency is significantly improved.

[0036] Embodiment 2

[0037] This embodiment provides a production process for 3D printing reinforced concrete precast composite slabs. The production process includes the following steps:

[0038] (1) Arrange multiple transverse steel bars 1 in parallel in sequence, and also arrange multiple longitudinal steel bars 2 in parallel in sequence, keeping the transverse steel bars 1 perpendicular to the longitudinal steel bars 2, thereby fabricating a steel mesh sheet 3, which is used as the precast composite slab skeleton. Refer to Figure 1 ;

[0039] (2) Clean the formwork table and perform projection positioning on the surface of the formwork table.

[0040] (3) According to the positioning result, erect the steel mesh sheet 3 by the method of adding spacer bars, which can also ensure the thickness of the protective layer of the reinforced concrete precast composite slab. After erection, print the first layer of concrete 4 (refer to Figure 2 ); among them, the border of the first-layer printed concrete 4 is slightly higher than the steel bars, and the discharge amount of the concrete 4 should be large. Extrude the concrete 4 through the print head 5 to make the concrete 4 fill the space below the steel bars. In addition, due to the thixotropy of the concrete 4, there will be gaps 6 below the steel bars during natural filling (refer to Figure 3 ). For a fixed formwork table, a small vibration is applied by a vibrator for filling; in addition, large-grained sand or fine gravel is used for printing the concrete, which can improve the surface roughness of the printing material and eliminate the subsequent border roughening process.

[0041] (4) For a fixed formwork table, the printed steel mesh sheet 3 waits for the border to harden through the transition station, and then install magnetic positioning clamps on the outside of the border to prevent slippage during the concrete pouring and vibration process. Then install truss steel bars and embedded pipelines, and pour, cure, roughen, cure, and demold in sequence to obtain the 3D printed reinforced concrete precast composite slab.

[0042] It should be emphasized that for comparison with the prior art, in this embodiment, the designed thickness of the reinforced concrete precast composite slab is 60 mm, the diameter of the steel bars is 8 mm, the thickness of the protective layer 7 is 15 mm, and it is printed in two layers. The thickness of the first layer of printing 8 is 33 mm (15 mm + 8 mm × 2 + 2 mm allowance, refer to Figure 4 ); the thickness of the second layer of printing 9 is 28 mm (refer to Figure 4 ), and the discharge amount is reduced. The total printing height is 61 mm. In order to fill the gaps, a small vibration is applied to the formwork table, so the border height will be reduced by about 1 mm, and the total height is reduced to about 60 mm, meeting the design expectation. Wait for the border to harden and install truss steel bars at the same time, and then perform subsequent processes. Therefore, when the thickness of the precast slab is 60 mm, the solution of this embodiment is to print continuously twice, while the prior art requires four times of printing, and the efficiency is significantly improved.

[0043] Example 3

[0044] This embodiment provides a production process for 3D printing a reinforced concrete precast composite slab. The production process includes the following steps:

[0045] (1) Arrange multiple transverse steel bars 1 in parallel in sequence, and also arrange multiple longitudinal steel bars 2 in parallel in sequence, keeping the transverse steel bars 1 perpendicular to the longitudinal steel bars 2. In this way, a steel mesh sheet 3 is fabricated and used as the precast composite slab skeleton. Refer to Figure 1 ;

[0046] (2) Clean the formwork table and perform projection positioning on the surface of the formwork table;

[0047] (3) According to the positioning result, use the method of adding spacer bars to erect the steel mesh sheet 3, which can also ensure the thickness of the protective layer of the reinforced concrete precast composite slab. After erection, print the first layer of concrete 4 (refer to Figure 2 ); among them, the border of the first-layer printed concrete 4 is slightly higher than the steel bars, and the discharge amount of the concrete 4 should be large. The concrete 4 is extruded by the print head 5 to fill the space below the steel bars; in addition, due to the thixotropy of the concrete 4, there will be a gap 6 below the steel bars during natural filling (refer to Figure 3 ). For a fixed formwork table, a small vibration is applied by a vibrator for filling; in addition, large-grained sand or fine stones are used for printing the concrete, which can improve the surface roughness of the printing material and eliminate the subsequent border scabbing process;

[0048] (4) For a fixed formwork table, the printed steel mesh sheet 3 waits at the transition station for the border to harden, and then a magnetic positioning fixture is installed on the outside of the border to prevent slipping during the concrete pouring and vibration process. Then, truss steel bars and embedded pipelines are installed, and pouring, curing, roughening, curing, and demolding are carried out in sequence to obtain the 3D printed reinforced concrete precast composite slab.

[0049] It should be emphasized that in this embodiment, the designed thickness of the reinforced concrete precast composite slab is 61 mm, the diameter of the steel bars is 8 mm, the thickness of the protective layer 7 is 15 mm, and it is printed in two layers. The printing thickness 8 of the first layer is 33 mm (15 mm + 8 mm × 2 + 2 mm allowance, refer to Figure 4 ); the printing thickness 9 of the second layer is 29 mm (refer to Figure 4 ), and the discharge amount is reduced. The total printing height is 62 mm. In order to fill the gap, a small vibration is applied to the formwork table, so the border height will be reduced by about 1 mm, and the total height is reduced to about 61 mm, meeting the design expectation. While waiting for the border to harden, truss steel bars are installed, and then subsequent processes are carried out.

[0050] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims described above.

Claims

1. A production process for 3D printing reinforced concrete precast composite slabs, characterized in that, The production process includes the following steps: (1) Clean the mold table and position on the surface of the mold table; (2) Erect the steel mesh according to the positioning result, and print the border of the composite slab on the erected steel mesh by a 3D concrete printer; (3) Through the vibration of the mold table, make the 3D printed concrete fill the gap under the steel bars; (4) After the border hardens, pour concrete into the inner side of the border; (5) Cure, roughen, maintain, demold and avoid surface cleaning in sequence, then the 3D printed reinforced concrete precast composite slab is obtained.

2. The production process of the 3D printed reinforced concrete precast composite slab according to claim 1, characterized in that, In step (1), clean the mold table and conduct scribing positioning or projection positioning on the surface of the mold table.

3. The production process of the 3D printed reinforced concrete precast composite slab according to claim 1, characterized in that, In step (2), according to the positioning result, erect the steel mesh by means of heightening to meet the requirement of the protective layer thickness of the composite slab.

4. The production process of the 3D printed reinforced concrete precast composite slab according to claim 1, characterized in that, In step (2), after the erection is completed, conduct 2 - 3 layers of 3D reinforced concrete printing on the border of the steel mesh.

5. The production process of the 3D printed reinforced concrete precast composite slab according to claim 1, characterized in that, In step (3), for a moving mold table, generate vibration by walking or a small vibrator; for a fixed mold table, generate vibration by a small vibrator.

6. The production process of the 3D printed reinforced concrete precast composite slab according to claim 1, characterized in that, In step (4), after the border hardens, install magnetic suction clamps on the border and the steel mesh to prevent the border from slipping during the concrete pouring and vibration process.

7. The production process of the 3D printed reinforced concrete precast composite slab according to claim 1, characterized in that In step (5), the demolding means directly lifting the composite slab to disconnect it from the bottom mold.

8. The production process of the 3D printed reinforced concrete precast composite slab according to claim 1, characterized in that, In step (5), the so-called avoiding surface cleaning means using coarse sand or fine aggregate as the printed concrete material to increase the surface roughness of the printed material and avoid the edge surface cleaning step in the production of conventional composite slabs.

9. A 3D printed reinforced concrete precast composite slab prepared by the production process according to any one of claims 1 - 8.

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