A pouring construction system and construction method for near-zero magnetic concrete structure

Abstract

The application discloses a pouring construction system and a construction method for near-zero magnetic concrete structure, and the pouring construction system comprises a vibrating device and a troweling device, wherein the vibrating device is used for vibrating the low-magnetic concrete, and the troweling device is used for demagnetizing and troweling the concrete. In the application, the cementitious material particles in the concrete are first vibrated to a disordered state by the vibrating device, the residual magnetic value is reduced by destroying the magnetic state of the cementitious material particles, the low-magnetic concrete is formed, then the environmental magnetic field is dynamically demagnetized, the problem that the low-magnetic concrete formed by the vibrating is magnetized by the environmental magnetic field and the residual magnetic value is increased before the cementitious material particles form a net-like lapping structure is avoided, the residual magnetic value in the hardening process of the concrete is further avoided, finally, the surface is troweled by the troweling device, and the pouring construction of the near-zero magnetic concrete is realized.

Description

Technical Field

[0001] This invention relates to the field of near-zero magnetic concrete construction technology, specifically to a pouring construction system and method for near-zero magnetic concrete structures. Background Technology

[0002] Low-magnetic concrete, as a special type of concrete material, is often used in the construction of projects such as low-magnetic medical rooms, low-magnetic geomagnetic stations, and demagnetization laboratories to form a closed low-magnetic concrete structural space, ensuring that sensitive instruments and equipment are not affected by strong external magnetic fields during use.

[0003] Existing research indicates that the remanence of ordinary concrete ranges from several hundred to several thousand nT. After pouring using various low-magnetization production methods, the remanence of conventional concrete is at least 3 nT, and it is easily magnetized by the surrounding geomagnetic field or strong magnetic field sources during the pouring process. However, for critical scientific devices such as large-scale scientific facilities with extremely weak magnetic fields and high-end zero-magnetic medical equipment, the design requirements for extremely weak environmental magnetic fields are extremely low, requiring the remanence of concrete to not exceed 0.5 nT. This type of concrete is called near-zero magnetic concrete. However, when using near-zero magnetic concrete for construction, although the remanence of the near-zero magnetic concrete itself meets the requirements, it is still easily magnetized by the environmental magnetic field during construction, resulting in a post-construction environmental magnetic field that does not meet the requirements, making the construction of an extremely weak environmental magnetic field extremely difficult. This invention provides a pouring and construction system and method for near-zero magnetic concrete structures to solve the above problems. Summary of the Invention

[0004] This invention provides a casting construction system and method for near-zero magnetic concrete structures, which achieves the casting construction of near-zero magnetic concrete structures through demagnetization vibration and dynamic demagnetization.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: A pouring construction system for near-zero magnetic concrete structures includes a vibrating device and a smoothing device, wherein the vibrating device is used for vibrating the concrete and the smoothing device is used for environmental demagnetization and smoothing the concrete. The vibration equipment includes a vibrator and a measuring device. The vibrator is used for vibrating concrete, and the measuring device is used to measure the state of the concrete after vibration. The smoothing equipment includes a demagnetizing mechanism and a smoothing mechanism. The demagnetizing mechanism is mounted on the smoothing mechanism. The demagnetizing mechanism is used to dynamically demagnetize the ambient magnetic field after the concrete is vibrated. The smoothing mechanism is used to smooth the concrete after it has been vibrated.

[0006] Furthermore, the vibrator includes a first power unit, a shielded chamber, a connecting pipe, and a vibrating rod. The first power unit is installed in the shielded chamber, and the vibrating rod is connected to the first power unit through the connecting pipe.

[0007] Furthermore, the shielded room includes a protective layer, a shielding layer, a protective layer, and a demagnetizing layer. The protective layer and the shielding layer are alternately stacked on the inner side of the protective layer, and the demagnetizing layer is disposed on the outer side of the protective layer.

[0008] Furthermore, the measuring device includes a measuring probe and a display. The measuring probe is used to insert into the concrete to measure the phase angle of the concrete, and the display is used to display the measured phase angle of the concrete.

[0009] Furthermore, the smoothing mechanism includes a second power unit, a smoothing plate, and an outer frame. The second power unit is mounted on the outer frame, and the smoothing plate is located at the bottom of the outer frame and connected to the second power unit. The outer frame includes a frame, wheels, and handrails, with the wheels and handrails located on the front side of the frame.

[0010] Furthermore, the demagnetizing mechanism includes a detection device and a demagnetizing device. The detection device is mounted on the frame and is used to detect the ambient magnetic field. The demagnetizing device is located on the outer periphery of the frame and is used to demagnetize the ambient magnetic field.

[0011] Furthermore, the detection device is a fluxgate, and the demagnetizing device is a demagnetizing coil wound around the outer periphery of the frame.

[0012] Furthermore, the vibrating rod is made of 316L material, and the shielding layer is permalloy.

[0013] A construction method for a casting system for near-zero magnetic concrete structures includes the following steps: S1, Concrete pouring: Concrete is poured in layers, with each layer not exceeding 300mm in thickness. S2, Conventional concrete vibration: After the concrete is poured, the concrete is subjected to initial conventional vibration. S3, Demagnetizing and Vibrating Concrete: 1 hour before the initial setting of concrete, demagnetize and vibrate the concrete. When demagnetizing and vibrating, repeat the operation by vibrating first and then measuring until the phase angle of the concrete after vibration is not less than 85°. Then lift the vibrator outside the concrete. S4, Dynamic demagnetization of concrete: The smoothing equipment is transferred to the concrete after vibration, and the demagnetizing device is used to dynamically demagnetize the ambient magnetic field. During dynamic demagnetization, the magnetic field strength generated by the demagnetizing device is ten times the detected ambient magnetic field strength. S5, Concrete Smoothing: After the dynamic demagnetization of the concrete is completed, the concrete surface is smoothed by a smoothing mechanism, and then the concrete is allowed to harden.

[0014] Furthermore, in step S4, after the dynamic demagnetization is completed, the phase angle of the concrete is measured by a measuring probe. If the concrete phase angle is not higher than 10°, the dynamic demagnetization is stopped. If the concrete phase angle is higher than 10°, the dynamic demagnetization is performed again. When the concrete phase angle is between 10-20°, the dynamic demagnetization is performed again for 1 minute. For every 10° increase in the concrete phase angle, the demagnetization time is increased by 1 minute.

[0015] The beneficial effects of this invention are as follows: First, the cementitious material particles in the concrete are vibrated to a disordered state, thereby reducing the residual magnetic value by disrupting their magnetic state and forming low-magnetic concrete. Then, the ambient magnetic field is dynamically demagnetized to prevent the low-magnetic concrete formed by vibration from being magnetized by the ambient magnetic field before forming the network overlap structure of cementitious material particles, thus avoiding the problem of increased residual magnetic value. Finally, the surface is smoothed by a smoothing device, realizing the pouring and construction of near-zero magnetic concrete. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the vibratory demagnetization working state of the vibratory device of the present invention; Figure 2 A schematic diagram of the smoothing device of the present invention in the dynamic environmental demagnetization working state. Figure 3 This is a schematic diagram of the smoothing device of the present invention; Figure 4 This is a schematic diagram of the vibrator structure of the present invention; Figure 5 This is a schematic diagram of the layered structure of the shielding room of the present invention; Figure 6 This is a schematic diagram illustrating the relationship between phase angle and residual magnetism during the concrete vibration demagnetization process of the present invention; Figure 7 This is a schematic diagram illustrating the relationship between the residual magnetism of concrete and the stage of stopping dynamic demagnetization, as presented in this invention.

[0017] Reference numerals: 100, Vibrating equipment; 200, Smoothing equipment; 1, Vibrator; 11, First power unit; 12, Shielding room; 121, Protective layer; 122, Shielding layer; 123, Protective layer; 124, Demagnetizing layer; 13, Connecting pipe; 14, Vibrating rod; 2, Measuring instrument; 21, Measuring probe; 22, Display; 3, Demagnetizing mechanism; 31, Detection device; 32, Demagnetizing device; 4, Smoothing mechanism; 41, Second power unit; 42, Smoothing plate; 43, Outer frame; 431, Frame; 432, Traveling wheel; 433, Handrail. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0020] like Figure 1 , 2 As shown, a construction system for pouring near-zero magnetic concrete structures includes a vibrating device 100 and a smoothing device 200. The vibrating device 100 is used for vibrating the concrete, and the smoothing device 200 is used for environmental demagnetization and smoothing the concrete.

[0021] The specific principle of this invention is as follows: Low-magnetic concrete has a low remanent magnetization value and is easily magnetized before solidification. Therefore, it is easily magnetized by the ambient magnetic field during pouring, leading to an increase in remanent magnetization value. After hardening, its remanent magnetization value does not meet the requirements of a very weak ambient magnetic field. Therefore, during concrete pouring, a vibrator 1 is first used to vibrate the concrete, and the phase angle of the concrete is measured during the vibration process. The phase angle is a direct observation parameter characterizing the degree of overlap of the cementitious material particle network structure in the concrete. When the interparticle network structure is destroyed, the cementitious material particles can undergo [further action / destruction]. The magnetic structure formed after being magnetized by the ambient magnetic field disappears upon free movement and rotation. The remanent magnetization value of the concrete at this time is obtained by reading the phase angle. When the remanent magnetization value meets the requirements, i.e., after the low magnetic concrete is formed, the vibration is stopped. Then, the ambient magnetic field is dynamically demagnetized by the demagnetizing mechanism 3 to prevent the low magnetic concrete that has not formed a mesh-like overlapping structure after vibration from being magnetized by the ambient magnetic field again. After the ambient magnetic field is dynamically demagnetized, the low magnetic concrete is smoothed to complete the construction. The remanent magnetization value of the final concrete structure is less than 0.5nT, realizing the pouring construction of near-zero magnetic concrete.

[0022] Furthermore, through laboratory experiments, it was observed that the flocculated network structure of cementitious particles in concrete with high remanent magnetization was destroyed during vibration. The particles could move freely and rearrange themselves. Simultaneously, the phase angle of the concrete also changed synchronously. The larger the phase angle, the greater the degree of destruction of the flocculated network structure, i.e., the existing magnetic domain structure. When the phase angle reached 85° or above, the flocculated network structure of cementitious particles in the concrete was completely destroyed. The cementitious particles moved and rotated freely, and the concrete was in a non-magnetic or low-magnetic state. After vibration stopped, the cementitious particles would be magnetized by the external magnetic field and move towards the direction of the strong magnetic field, thus forming a magnetic domain structure and exhibiting magnetism. If the external magnetic field was dynamically demagnetized immediately after vibration using an alternating magnetic field, the cementitious particles would also be in a disordered state due to the uncertain direction of the external magnetic field. After the cementitious particles were hardened in a disordered state, they would not exhibit a uniform magnetic arrangement, thus exhibiting low-magnetic or near-zero-magnetic concrete. As concrete hardens, the free activity of its cementitious particles decreases. With this decrease, a stable flocculated network structure forms between the cementitious particles. When the phase angle is no higher than 10°, it indicates that a stable flocculated network structure has been completely formed between the cementitious particles. At this point, the external magnetic field environment can no longer magnetize the cementitious particles, thus preventing an increase in the remanent magnetization value of the concrete. This ensures that the remanent magnetization value of the hardened concrete is no higher than 0.5 nT, achieving the construction of near-zero magnetic concrete building structures.

[0023] like Figure 6 As shown, commercially available ordinary cement and aggregates with a remanent magnetic value not exceeding 1 nT were used to prepare concrete in a normal ambient magnetic field. After the concrete was prepared, it was vibrated to demagnetize it. The remanent magnetic value of the same type of concrete was measured when it was vibrated to different phase angles. Since the remanent magnetic value of commercially available concrete is between tens and hundreds, the higher the degree of damage to the existing magnetic structure of the concrete by vibration, the lower the remanent magnetic value. When the phase angle was only 10°, the remanent magnetic value was as high as 115.7 nT, while when the phase angle reached 85°, the remanent magnetic value was only 0.4 nT, which meets the requirement of near-zero magnetism.

[0024] like Figure 7As shown, after concrete is vibrated and forms near-zero magnetic concrete, dynamic demagnetization needs to continue until a stable mesh-like overlap structure is formed to prevent the concrete from being remagnetized by the ambient magnetic field. Afterward, the concrete will remain in a near-zero magnetic state. Experiments have shown that the remanent magnetization value of the concrete varies significantly depending on when dynamic demagnetization is stopped at different stages before the formation of a stable mesh-like overlap structure. Without dynamic demagnetization after vibration demagnetization, the concrete will be remagnetized during hardening, resulting in a remanent magnetization value of 113.8 nT after hardening. However, if dynamic demagnetization is continued until a stable mesh-like overlap structure is formed, i.e., when the phase angle of the concrete is no higher than 10°, the remanent magnetization value after hardening is 0.3 nT, and the remanent magnetization value does not increase again.

[0025] like Figure 1 , 4 As shown, the vibration equipment 100 includes a vibrator 1 and a measuring device 2. The vibrator 1 is used to vibrate concrete and demagnetize the concrete by vibration, thereby destroying the magnetic structure in the concrete to form low-magnetic concrete. The measuring device 2 is used to measure the state of the concrete after vibration. By measuring the phase angle of the concrete, the residual magnetic value of the concrete at this time is obtained. After the phase angle meets the requirements, the vibration is stopped.

[0026] like Figure 2 , 3 As shown, the smoothing device 200 includes a demagnetizing mechanism 3 and a smoothing mechanism 4. The demagnetizing mechanism 3 is mounted on the smoothing mechanism 4. The demagnetizing mechanism 3 is used to dynamically demagnetize the ambient magnetic field after the concrete is vibrated. The smoothing mechanism 4 is used to smooth the near-zero magnetic concrete after vibration.

[0027] Furthermore, the vibrator 1 includes a first power unit 11, a shielding chamber 12, a connecting pipe 13, and a vibrating rod 14. The first power unit 11 is disposed in the shielding chamber 12 and is used to provide power to the vibrating rod 14. The shielding chamber 12 is used to shield the electromagnetic field generated when the first power unit 11 is working. The vibrating rod 14 is connected to the first power unit 11 through the connecting pipe 13, and the connecting pipe 13 is used to transmit the power of the first power unit 11 to the vibrating rod 14.

[0028] like Figure 5As shown, the shielded chamber 12 further includes a protective layer 121, a shielding layer 122, a protective layer 123, and a demagnetizing layer 124. The protective layer 121 and the shielding layer 122 are alternately stacked inside the protective layer 123, with one layer of protective layer 121 and one layer of shielding layer 122 alternately stacked, resulting in three layers of shielding layer 122. A protective layer 121 is placed between the outermost shielding layer 122 and the protective layer 123, for a total of four layers of protective layer 121. The demagnetizing layer 124 is placed outside the protective layer 123. The shielded chamber 12 using multiple layers of shielding layer 122 has an overall residual magnetism value not exceeding 30 nT.

[0029] Furthermore, the vibrating rod 14, the protective layer 123, and the metal components in the device are all made of 316L stainless steel, which is a near-zero magnetic material and will not magnetize the concrete. The protective layer 121 is a flexible insulating material that serves as a buffer and protector. The shielding layer 122 is permalloy, a commonly used magnetic shielding material. The demagnetizing layer 124 is a demagnetizing coil. The shielding layer 122 is easily magnetized by a magnetic field, so it needs to be demagnetized by the demagnetizing layer 124 before use.

[0030] like Figure 1 As shown, the measuring device 2 further includes a measuring probe 21 and a display 22. The measuring probe 21 is used to insert into the concrete to measure the phase angle of the concrete, and the display 22 is used to display the measured phase angle of the concrete.

[0031] Furthermore, the measuring probe 21 includes a motor, a probe, a normal force sensor, and a linear optical encoder. The probe is mounted on the motor, which is an EC motor. The EC motor is connected to the probe via an air bearing to ensure high-precision transmission with ultra-low deviation. The EC motor drives the probe to rotate in the concrete. The EC motor applies stress through the probe. The normal force sensor is connected to the probe to measure the stress on the probe. The linear optical encoder is connected to the EC motor. When the EC motor rotates, the grating generates a synchronous displacement. The receiver reads the angular displacement data of the grating, measures the angular displacement of the EC motor, and calculates the shear strain value from the angular displacement.

[0032] The phase angle is calculated by taking the acquired torque value to calculate the shear stress value and the acquired angular displacement to calculate the shear strain value, thus obtaining the phase angle of the concrete. The specific process is as follows: The probe is set with an angular frequency ω and a strain amplitude γ0. The strain amplitude is achieved by controlling the angular displacement. The EC motor drives the probe to rotate according to the sinusoidal position command. The actual applied strain signal γ(t) = γ0*sin(ωt); the concrete resists the applied strain, which is manifested as a torque M(t). The normal force sensor measures M(t) in real time. The measured torque is used to calculate the stress τ(t) through geometric transformation, τ(t) = τ0*sin(ωt+δ); Fourier transform is used to perform Fourier transform on the acquired strain signal and stress signal and compare them to determine the time difference between them. Then, the time difference is converted into a phase angle difference δ, thus obtaining the phase angle of the concrete. After measuring the phase angle of the concrete, the corresponding remanence value of the concrete at this time is found by referring to a table.

[0033] like Figure 3 As shown, the smoothing mechanism 4 further includes a second power unit 41, a smoothing plate 42, and an outer frame 43. The second power unit 41 is mounted on the outer frame 43 and is used to drive the smoothing plate 42. The smoothing plate 42 is located at the bottom of the outer frame 43 and connected to the second power unit 41 for smoothing the concrete surface. The outer frame 43 includes a frame 431, wheels 432, and handrails 433. The frame 431 is used to mount the smoothing plate 42, wheels 432, and handrails 433. The wheels 432 and handrails 433 are located on the front side of the frame 431.

[0034] like Figure 2 , 3 As shown, the demagnetizing mechanism 3 further includes a detection device 31 and a demagnetizing device 32. The detection device 31 is a fluxgate mounted on the frame 431 and is used to detect the ambient magnetic field. The demagnetizing device 32 is a demagnetizing coil wound around the outer periphery of the frame 431 and is used to demagnetize the ambient magnetic field.

[0035] like Figure 2 , 3 As shown, the frame 431 further includes a frame body and an outer cover. The frame body is located on the upper part of the outer cover and is used to install and place the second power device 41, the walking wheel 432 and the handrail 433. The outer cover is an open cover at the bottom. The wiping plate 42 is located in the outer cover. The wiping plate 42 and the outer cover are made of 316L stainless steel. The demagnetizing device 32 is surrounded on the outer periphery of the outer cover.

[0036] A construction method for a casting system for near-zero magnetic concrete structures includes the following steps: S1, Concrete pouring: Concrete is poured in layers, with each layer not exceeding 300mm in thickness. S2, Conventional concrete vibration: After the concrete is poured, it is subjected to initial conventional vibration to make the concrete dense. S3, Demagnetizing and Vibrating Concrete: 1 hour before the initial setting of concrete, demagnetize and vibrate the concrete. During demagnetizing and vibrating, repeat the operation by vibrating first and then measuring until the phase angle of the concrete after vibration is not less than 85°. Then, lift the vibrator 14 outside the concrete. S4, Dynamic demagnetization of concrete: The smoothing equipment 200 is transferred to the concrete after vibration, and the demagnetizing device 32 is used to dynamically demagnetize the ambient magnetic field. During dynamic demagnetization, the magnetic field strength generated by the demagnetizing device 32 is ten times the detected ambient magnetic field strength. Dynamic demagnetization is achieved by using a strong alternating magnetic field generated by the demagnetizing device 32 to counteract the ambient magnetic field and simultaneously act on the vibrated concrete. Demagnetization is carried out by utilizing the decreasing hysteresis loop, thereby preventing the ambient magnetic field from remagnetizing the demagnetized low-magnetic concrete and ensuring that the concrete forms a mesh-like overlapping structure and hardens in a state of low residual magnetic value. After dynamic demagnetization is completed, the phase angle of the concrete is measured by measuring probe 21. If the phase angle of the concrete is not higher than 10°, dynamic demagnetization is stopped. If the phase angle of the concrete is higher than 10°, dynamic demagnetization is performed again. When the concrete phase angle is between 10-20°, perform dynamic demagnetization for another minute. For every 10° increase in the concrete phase angle, add another minute to the dynamic demagnetization time. S5, Concrete Smoothing: After the concrete dynamic demagnetization is completed, the concrete surface is smoothed by the smoothing mechanism 4, and then the concrete is allowed to solidify.

[0037] Furthermore, in step S3, when performing concrete demagnetization vibration, the specific operation is as follows: the vibrator 14 is inserted into the concrete at a speed of 0.3-0.5 m / s. After it is inserted into the concrete, the concrete is first vibrated at a frequency of 150 Hz for 8 seconds. Then, the measuring probe 21 is inserted into the concrete at a distance of 10-15 cm from the tip of the probe. The concrete is then vibrated at a frequency of 1 Hz with a shear strain not exceeding 1% for 2-5 seconds to measure the phase angle of the concrete. During measurement, if the concrete phase angle is lower than 85°, increase the frequency of the vibrator 14 by 50Hz and vibrate the concrete for 8 seconds. Measure the concrete phase angle again. If the concrete phase angle is not lower than 85°, stop vibrating. If the concrete phase angle is still lower than 85°, increase the frequency of the vibrator 14 by another 50Hz and vibrate the concrete for 8 seconds. Repeat the above operation until the concrete phase angle is not lower than 85°. Once the concrete phase angle meets the requirements, remove the vibrator 14 at a speed of 0.1 m / s.

[0038] Furthermore, during concrete demagnetization vibration in step S3, the vibration spacing is controlled within 1.0 times the effective radius of the vibrator, and a quincunx pattern is used.

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A casting construction system for near-zero magnetic concrete structures, characterized in that: It includes a vibrating device (100) and a smoothing device (200), wherein the vibrating device (100) is used for vibrating concrete, and the smoothing device (200) is used for environmental demagnetization and concrete smoothing; The vibrating device (100) includes a vibrator (1) and a measuring device (2), wherein the vibrator (1) is used for vibrating concrete and the measuring device (2) is used for measuring the state of concrete after vibration; The smoothing device (200) includes a demagnetizing mechanism (3) and a smoothing mechanism (4). The demagnetizing mechanism (3) is located on the smoothing mechanism (4). The demagnetizing mechanism (3) is used to dynamically demagnetize the ambient magnetic field after the concrete is vibrated. The smoothing mechanism (4) is used to smooth the concrete after it is vibrated. The vibrator (1) includes a first power unit (11), a shielded chamber (12), a connecting pipe (13), and a vibrating rod (14). The first power unit (11) is installed in the shielded chamber (12), and the vibrating rod (14) is connected to the first power unit (11) through the connecting pipe (13). The measuring device (2) includes a measuring probe (21) and a display (22). The measuring probe (21) is used to insert into the concrete to measure the phase angle of the concrete, and the display (22) is used to display the measured phase angle of the concrete. The demagnetizing mechanism (3) includes a detection device (31) and a demagnetizing device (32). The detection device (31) is used to detect the ambient magnetic field, and the demagnetizing device (32) is used to demagnetize the ambient magnetic field.

2. The casting and construction system for near-zero magnetic concrete structures according to claim 1, characterized in that: The shielding chamber (12) includes a protective layer (121), a shielding layer (122), a protective layer (123), and a demagnetizing layer (124). The protective layer (121) and the shielding layer (122) are alternately stacked on the inner side of the protective layer (123), and the demagnetizing layer (124) is disposed on the outer side of the protective layer (123).

3. The casting and construction system for near-zero magnetic concrete structures according to claim 1, characterized in that: The smoothing mechanism (4) includes a second power device (41), a smoothing plate (42), and an outer frame (43). The second power device (41) is mounted on the outer frame (43), and the smoothing plate (42) is mounted on the bottom of the outer frame (43) and connected to the second power device (41). The outer frame (43) includes a frame (431), wheels (432) and handrails (433), with the wheels (432) and handrails (433) located on the front side of the frame (431).

4. The casting and construction system for near-zero magnetic concrete structures according to claim 3, characterized in that: The detection device (31) is mounted on the frame (431), and the demagnetizing device (32) is mounted on the outer periphery of the frame (431).

5. The casting and construction system for near-zero magnetic concrete structures according to claim 4, characterized in that: The detection device (31) is a fluxgate, and the demagnetizing device (32) is a demagnetizing coil, which is wound around the outer periphery of the frame (431).

6. The casting and construction system for near-zero magnetic concrete structures according to claim 2, characterized in that: The vibrating rod (14) is made of 316L material, and the shielding layer (122) is made of permalloy.

7. A construction method for a near-zero magnetic concrete structure casting system according to claim 1, characterized in that, Includes the following steps, S1, Concrete pouring: Concrete is poured in layers, with each layer not exceeding 300mm in thickness. S2, Conventional concrete vibration: After the concrete is poured, the concrete is subjected to initial conventional vibration. S3, Demagnetizing and vibrating concrete: 1 hour before the initial setting of concrete, demagnetize and vibrate the concrete. When demagnetizing and vibrating, the method of vibrating first and then measuring is repeated until the phase angle of the concrete after vibration is not less than 85°. Then the vibrator (14) is lifted outside the concrete. S4, Dynamic demagnetization of concrete: The smoothing equipment (200) is transferred to the concrete after vibration and the demagnetizing device (32) is used to dynamically demagnetize the ambient magnetic field. During dynamic demagnetization, the magnetic field strength generated by the demagnetizing device (32) is ten times the detected ambient magnetic field strength. S5, Concrete smoothing: After the concrete dynamic demagnetization is completed, the concrete surface is smoothed by the smoothing mechanism (4), and then the concrete is left to harden.

8. A construction method for a near-zero magnetic concrete structure casting system according to claim 7, characterized in that: In step S4, after the dynamic demagnetization is completed, the phase angle of the concrete is measured by the measuring probe (21). If the phase angle of the concrete is not higher than 10°, the dynamic demagnetization is stopped. If the phase angle of the concrete is higher than 10°, the dynamic demagnetization is performed again. When the concrete phase angle is between 10-20°, dynamic demagnetization is performed again for 1 minute, and the dynamic demagnetization time is increased by 1 minute for every additional 10° the concrete phase angle exceeds.

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