An adaptive vacuum dehydration method and device for fresh concrete

Abstract

The present invention discloses an adaptive vacuum dehydration method and device for fresh concrete, constructs a vacuum adaptive control algorithm for characterizing the relationships between the expected vacuum treatment depth and the vacuum degree, the expected vacuum treatment depth and the vacuum treatment time, and the concrete surface strength and the vacuum degree and the water removal amount; uses the vacuum adaptive control algorithm to generate an adaptive vacuum treatment plan for different working conditions; or determines a constant vacuum treatment plan according to the working condition requirements; under the adaptive vacuum treatment plan or the constant vacuum treatment plan, autonomously controls the vacuum dehydration treatment process of the fresh concrete, and monitors the water removal amount and the vacuum compactness in real time during the vacuum dehydration treatment process, and quantitatively evaluates the vacuum treatment effect. The present invention can adaptively generate a vacuum treatment plan for different working conditions, autonomously control the whole process of vacuum treatment according to the plan, and monitor the water removal amount and the vacuum compactness of fresh concrete in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent concrete construction, and particularly relates to an adaptive vacuum dehydration method and device for fresh concrete. Background Technique

[0002] Vacuum dehydration technology is a mechanical water absorption measure to improve the surface vacuum density and strength of concrete. By creating a vacuum environment on the surface of fresh concrete, a large negative pressure is formed inside and outside the concrete, causing internal water and bubbles to be discharged together. During the vacuum dehydration process, the water-binder ratio on the surface layer of fresh concrete decreases, and the vacuum density increases, resulting in a decrease in the porosity of the hardened concrete surface layer and a reduction in the capillary pore diameter, greatly improving the physical and mechanical properties and durability of the surface concrete. From the analysis of the vacuum compaction effect, vacuum dehydration can be regarded as a process of continuously compacting the surface concrete. The vacuum negative pressure generated by vacuum dehydration technology on the surface of fresh concrete is equivalent to a process of continuously compacting the surface layer of concrete under the same amount of compaction pressure. Under the action of the compaction pressure, the water on the surface layer of fresh concrete is discharged, reducing the effective water-binder ratio on the concrete surface and achieving the purpose of improving the surface strength and durability of the concrete.

[0003] The existing vacuum dehydration technology is a commonly used surface strengthening technology for structures such as highway pavements and mass concrete. The patent "Concrete Vacuum Dehydration Construction Method (CN 106320711 B)" invented a concrete vacuum dehydration construction method, which has the advantages of simple construction, good sealing performance, and significant improvement in surface strength. However, this method requires manual control of the vacuum degree and vacuum time throughout the process, and no calculation method for the vacuum degree and vacuum treatment time is established. The patent "Air-entrained Vacuum Concrete Pavement and Construction Method (CN200910161844.3)" conducts vacuum dehydration treatment on fresh air-entrained concrete. This method establishes the relationship between the two parameters of the vacuum degree and vacuum treatment time and the vacuum depth, and proposes the recommended vacuum degree and vacuum treatment time under different working conditions, but does not propose a control method for the vacuum degree and vacuum treatment time, lacking real-time monitoring and regulation of the vacuum treatment process. The patent "A Device for Concrete Vacuum Dehydration Process (CN 213837777 U)" invented a set of movable concrete vacuum dehydration devices, but this device can only perform vacuum treatment with a constant vacuum degree. At the same time, it is unable to quantitatively evaluate the improvement effect of fresh concrete after vacuum dehydration.

[0004] Currently, the following problems still exist in the concrete vacuum dehydration method and device:

[0005] (1) Lack of a vacuum dehydration quantification control model: There is a lack of a reasonable calculation model for the concrete vacuum degree and vacuum treatment time, and no clear concrete vacuum dehydration system and method have been formed;

[0006] (2) Low level of intelligence in vacuum dehydration technology: The existing concrete vacuum dehydration devices cannot autonomously adjust the vacuum degree on the concrete surface according to the actual working conditions, resulting in a low level of intelligence in vacuum dehydration technology.

[0007] (3) Unable to evaluate the vacuum dehydration effect: At present, there is no suitable method to evaluate the improvement effect on the surface of fresh concrete, and the concrete vacuum dehydration device cannot evaluate the improvement effect in real time.

[0008] Therefore, how to provide an adaptive vacuum dehydration method and device for fresh concrete that can adaptively control the entire vacuum treatment process for different working conditions and real-time monitor the water dehydration amount and vacuum density of fresh concrete is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0009] In view of this, the present invention provides an adaptive vacuum dehydration method and device for fresh concrete, which can adaptively generate a vacuum treatment plan for different working conditions, autonomously control the entire vacuum treatment process according to the plan, and real-time monitor the water dehydration amount and vacuum density of fresh concrete.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] An adaptive vacuum dehydration method for fresh concrete, comprising:

[0012] Constructing a vacuum adaptive control algorithm for characterizing the relationship between the expected vacuum treatment depth and the vacuum degree, the relationship between the expected vacuum treatment depth and the vacuum treatment time, and the relationship between the concrete surface strength and the vacuum degree and the water dehydration amount;

[0013] Using the vacuum adaptive control algorithm to generate an adaptive vacuum treatment plan for different working conditions; or determining a constant vacuum treatment plan according to the working condition requirements;

[0014] Under the adaptive vacuum treatment plan or the constant vacuum treatment plan, autonomously controlling the vacuum dehydration treatment process of fresh concrete;

[0015] Real-time monitoring the water dehydration amount and vacuum density of fresh concrete during the vacuum dehydration treatment process, and quantitatively evaluating the vacuum treatment effect.

[0016] Further, in the above-mentioned adaptive vacuum dehydration method for fresh concrete, the constant vacuum treatment plan is: presetting a constant vacuum degree and a constant vacuum treatment time, performing vacuum dehydration on fresh concrete under the constant vacuum degree, and stopping the vacuum dehydration after reaching the constant vacuum treatment time;

[0017] The adaptive vacuum treatment scheme includes three types, namely the expected vacuum depth control mode, the expected strength control mode, and the expected vacuum density control mode;

[0018] Among them, the expected vacuum depth control mode is as follows: under the condition of meeting the expected vacuum treatment depth, the adaptive vacuum degree and the adaptive vacuum treatment time are calculated using the vacuum adaptive control algorithm, and the fresh concrete is subjected to vacuum dehydration at the adaptive vacuum degree. After reaching the adaptive vacuum treatment time, the vacuum dehydration is stopped;

[0019] The expected strength control mode is as follows: under the condition of meeting the expected surface strength of the concrete, the adaptive vacuum degree and the expected water removal amount are calculated using the vacuum adaptive control algorithm, and the fresh concrete is subjected to vacuum dehydration at the adaptive vacuum degree. After reaching the expected water removal amount, the vacuum dehydration is stopped;

[0020] The expected vacuum density control mode is as follows: the initial density of the fresh concrete is measured using a nuclear density emitter, and the expected density required for the concrete is input. The fresh concrete is subjected to vacuum dehydration at a set vacuum degree. After reaching the expected density, the vacuum dehydration is stopped.

[0021] Furthermore, in the above-mentioned method for adaptively vacuum dehydrating fresh concrete, the relationship between the expected vacuum treatment depth and the vacuum degree is as follows:

[0022]

[0023] Among them, P vx is the vacuum degree at the expected vacuum treatment depth; P v is the vacuum degree on the concrete surface; H m is the limit depth of vacuum treatment, taking 200 mm; h x is the expected vacuum treatment depth.

[0024] Furthermore, in the above-mentioned method for adaptively vacuum dehydrating fresh concrete, the relationship between the expected vacuum treatment depth and the vacuum treatment time is as follows:

[0025]

[0026] Among them, q0 is the initial volume of water in the concrete per unit volume; α is the proportionality coefficient, taking α = 100.

[0027] Furthermore, in the above-mentioned method for adaptively vacuum dehydrating fresh concrete, the relationship between the concrete surface strength and the vacuum degree and the water removal amount is as follows:

[0028]

[0029] Among them, W eis the mass of water after vacuum dehydration; C e is the mass of the gelling material after vacuum dehydration; U wi is the water content per unit volume before vacuum dehydration; U ci is the cement content per unit volume before vacuum dehydration; (S f / H) = 0.063 + 0.0181·logP vx (S f / H ≥ 0) is the vacuum compaction amount of concrete per unit height; S f is the maximum compaction degree of concrete; H is the height of the concrete specimen; ρ is the density of water; β is the slump correction value of concrete, which is related to the slump of fresh concrete. When the slump of fresh concrete is less than 50 mm, β takes 1.5; when the slump of fresh concrete is 50 mm - 150 mm, β takes 1.2; when the slump of fresh concrete is 150 - 200 mm, β takes 1; when the slump of fresh concrete is 200 mm - 250 mm, β takes 0.9; when the slump of fresh concrete is greater than 250 mm, β takes 0.8.

[0030] Furthermore, in the above-mentioned method for vacuum dehydration of fresh concrete, the vacuum density of fresh concrete is the ratio of the measured density of fresh concrete to the expected density of fresh concrete.

[0031] The present invention also discloses an apparatus for vacuum dehydration of fresh concrete, comprising: an adaptive vacuum control subsystem, a vacuum adsorption subsystem, and a collection and display subsystem;

[0032] The adaptive vacuum control subsystem is used to pre-embed a vacuum adaptive control algorithm for characterizing the relationship between the expected vacuum treatment depth and the vacuum degree, the relationship between the expected vacuum treatment depth and the vacuum treatment time, and the relationship between the concrete surface strength and the vacuum degree and the water removal amount, and use the vacuum adaptive control algorithm to generate an adaptive vacuum treatment plan for different working conditions or determine a constant vacuum treatment plan according to the working condition requirements;

[0033] The adsorption end of the vacuum adsorption subsystem acts on the surface of fresh concrete and is used to independently control the vacuum dehydration treatment process of fresh concrete under the adaptive vacuum treatment plan or the constant vacuum treatment plan;

[0034] The collection and display subsystem is used to monitor the water removal amount and the vacuum density of fresh concrete during the vacuum dehydration treatment process in real time.

[0035] Further, in the above-mentioned self-adaptive fresh concrete vacuum dewatering device, the vacuum adsorption subsystem includes a vacuum suction pad, a vacuum suction cup, a vacuum conduit, a vacuum degree sensor, a vacuum regulating valve, a vacuum pump, and a control box; the vacuum pump is installed inside the control box; one end of the vacuum suction cup in contact with the fresh concrete is installed with the vacuum suction pad through a magnetic sealing strip, and the other end is communicated with the vacuum pump through the vacuum conduit; both the vacuum degree sensor and the vacuum regulating valve are installed at one end of the vacuum conduit close to the vacuum pump.

[0036] Further, in the above-mentioned self-adaptive fresh concrete vacuum dewatering device, the collection and display subsystem includes: a gas-water separation device, a lifting platform, a mass sensor, a nuclear density emitter, and a display installed inside the control box;

[0037] The mass sensor is installed on the lifting platform and is used to collect the water dewatering amount of the fresh concrete collected by the gas-water separation device in real time;

[0038] The nuclear density emitter is installed on the back of the vacuum suction cup and is aligned with the surface of the fresh concrete, and is used to monitor the density of the fresh concrete in real time;

[0039] The display is embedded on the surface of the control box and is used to display the vacuum degree, the water dewatering amount, and the vacuum compactness of the fresh concrete in real time.

[0040] Further, in the above-mentioned self-adaptive fresh concrete vacuum dewatering device, a cesium-137 γ source is arranged inside the nuclear density detector, and the released γ rays enter the fresh concrete and collide with the outer electrons of the substance atoms to generate Compton scattering. By measuring the number of γ rays after scattering, the actual density of the fresh concrete is obtained.

[0041] From the above technical solutions, it can be seen that compared with the prior art, the present invention discloses a self-adaptive fresh concrete vacuum dewatering method and device, which has the following beneficial effects:

[0042] 1. The present invention has strong applicability and high intelligence. By constructing a vacuum adaptive control algorithm, a vacuum treatment plan is adaptively proposed for different working conditions, and the whole process of vacuum treatment is autonomously controlled according to the plan, and the vacuum termination condition is clear, and the intelligence level is relatively high;

[0043] 2. The present invention can monitor the process in real time and quantitatively evaluate the effect. The water dewatering amount and the vacuum compactness of the fresh concrete can be monitored in real time, and when the preset vacuum treatment effect is achieved, a quantitative evaluation of the vacuum effect can be carried out. Description of the Drawings

[0044] 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 in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0045] Figure 1 It is a flowchart of the adaptive fresh concrete vacuum dehydration method provided by the present invention;

[0046] Figure 2 It is a schematic external structure diagram of the adaptive fresh concrete vacuum dehydration device provided by the present invention;

[0047] Figure 3 It is a schematic internal structure diagram of the adaptive fresh concrete vacuum dehydration device provided by the present invention. Detailed implementation manners

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0049] As Figure 1 shown, the embodiments of the present invention disclose an adaptive fresh concrete vacuum dehydration method, including the following steps:

[0050] S1. Construct a vacuum adaptive control algorithm for characterizing the relationship between the expected vacuum treatment depth and the vacuum degree, the relationship between the expected vacuum treatment depth and the vacuum treatment time, and the relationship between the concrete surface strength and the vacuum degree and the water removal amount;

[0051] S2. Use the vacuum adaptive control algorithm to generate an adaptive vacuum treatment plan for different working conditions; or determine a constant vacuum treatment plan according to the working condition requirements;

[0052] S3. Under the adaptive vacuum treatment plan or the constant vacuum treatment plan, independently control the vacuum dehydration treatment process of the fresh concrete;

[0053] S4. Real-time monitor the water removal amount and the vacuum density of the fresh concrete during the vacuum dehydration treatment process, and quantitatively evaluate the vacuum treatment effect.

[0054] In a specific embodiment,

[0055] In S1, in the vacuum adaptive control algorithm, the relationship between the expected vacuum treatment depth and the vacuum degree is:

[0056]

[0057] Among them, P vx is the vacuum degree at the expected vacuum treatment depth; P v is the concrete surface vacuum degree; H m is the limit depth of vacuum treatment, taking 200 mm; h x is the expected vacuum treatment depth.

[0058] The relationship between the expected vacuum treatment depth and the vacuum treatment time is:

[0059]

[0060] Among them, q0 is the initial volume of water in unit volume of concrete; α is the proportionality coefficient.

[0061] The adaptive vacuum degree and the adaptive vacuum treatment time can be calculated according to Equation (1) and Equation (2).

[0062] The water content per unit volume (U wi ) and the cement content per unit volume (U ci ) before vacuum dehydration are calculated according to the water-binder ratio of fresh concrete, as shown in Equation (3).

[0063]

[0064] In the formula, U wi is the water content per unit volume before vacuum dehydration; U ci is the cement content per unit volume before vacuum dehydration; W i is the mass of water before vacuum dehydration; C i is the mass of the binder before vacuum dehydration; V is the volume of the specimen.

[0065] The expected strength of concrete can be converted into the water content per unit volume (U we ) and the cement content per unit volume (U ce ) after vacuum dehydration through Equation (4) and Equation (5).

[0066]

[0067] In the formula, W e is the mass of water after vacuum dehydration; C e is the mass of the binder after vacuum dehydration; α a , α b are regression coefficients; f b is the mortar strength of the binder at 28 d; f cu,0 is the expected prepared strength of concrete.

[0068]

[0069] Wherein, U we is the water content per unit volume after vacuum dehydration; U ce is the cement content per unit volume after vacuum dehydration.

[0070] The vacuum compaction amount of concrete has a linear relationship with the vacuum negative pressure. The better the vacuum treatment effect of fresh concrete is as the slump increases. The vacuum compaction amount of concrete when reaching the required strength is calculated by using formulas (6) and (7), and the vacuum negative pressure value required at a specified depth of concrete is calculated according to the calculation. Substitute it into formula (1) to calculate the required vacuum negative pressure value on the surface, that is, the vacuum degree that the vacuum pump should provide. The expected water removal amount can be calculated through formula (8).

[0071]

[0072] Wherein, S f / H is the vacuum compaction amount of concrete per unit height; ρ is the density of water; β is the slump correction value of concrete.

[0073] (S f / H) = 0.063 + 0.0181·log P vx (S f / H≥0) (7)

[0074] Formulas (6)-(7) characterize the relationship between the vacuum compaction amount of concrete per unit height and the vacuum degree and water removal amount. Among them, U wi is the mass of water after vacuum dehydration; U ci is the mass of cementitious material after vacuum dehydration; U wi is the water content per unit volume before vacuum dehydration; U ci is the cement content per unit volume before vacuum dehydration; (S f / H) = 0.063 + 0.0181·log P vx (S f / H≥0) is the vacuum compaction amount of concrete per unit height; S f is the maximum compaction degree of concrete; H is the height of the concrete specimen; ρ is the density of water; β is the slump correction value of concrete, which is related to the slump of fresh concrete. When the slump of fresh concrete is less than 50mm, β takes 1.5; when the slump of fresh concrete is 50mm - 150mm, β takes 1.2; when the slump of fresh concrete is 150 - 200mm, β takes 1; when the slump of fresh concrete is 200mm - 250mm, β takes 0.9; when the slump of fresh concrete is greater than 250mm, β takes 0.8.

[0075] ΔW = W i-W p (8)

[0076] Wherein, ΔW is the predicted vacuum water removal amount of the concrete.

[0077] In one embodiment, the fresh concrete vacuum density is the ratio of the measured fresh concrete density to the expected fresh concrete density. That is Where γ n is the measured density of the fresh concrete; γ m is the designed density of the fresh concrete. During operation, the parameters in the "expected vacuum density control" working mode can be selected according to the real-time measured vacuum density.

[0078] Specifically, in S2, the constant vacuum treatment scheme is: preset the constant vacuum degree and the constant vacuum treatment time, perform vacuum dehydration on the fresh concrete under the constant vacuum degree, and stop the vacuum dehydration after reaching the constant vacuum treatment time.

[0079] The adaptive vacuum treatment scheme includes three types, namely the expected vacuum depth control mode, the expected strength control mode, and the expected vacuum density control mode;

[0080] Among them, the expected vacuum depth control mode is: under the condition of meeting the expected vacuum treatment depth, use the vacuum adaptive control algorithm to calculate the adaptive vacuum degree and the adaptive vacuum treatment time, perform vacuum dehydration on the fresh concrete under the adaptive vacuum degree, and stop the vacuum dehydration after reaching the adaptive vacuum treatment time;

[0081] The expected strength control mode is: under the condition of meeting the expected surface strength of the concrete, use the vacuum adaptive control algorithm to calculate the adaptive vacuum degree and the predicted water removal amount, perform vacuum dehydration on the fresh concrete under the adaptive vacuum degree, and stop the vacuum dehydration after reaching the predicted water removal amount;

[0082] The expected vacuum density control mode is: measure the initial density of the fresh concrete by using a nuclear density emitter, input the expected density that the concrete needs to reach, perform vacuum dehydration on the fresh concrete at the set vacuum degree, and stop the vacuum dehydration after reaching the expected density.

[0083] As Figures 2-3 shown, the embodiment of the present invention also provides an adaptive fresh concrete vacuum dehydration device, including: an adaptive vacuum control subsystem, a vacuum adsorption subsystem, and a collection and display subsystem;

[0084] The adaptive vacuum control subsystem is used to pre-embed a vacuum adaptive control algorithm for characterizing the relationship between the expected vacuum treatment depth and the vacuum degree, the relationship between the expected vacuum treatment depth and the vacuum treatment time, and the relationship between the concrete surface strength and the vacuum degree and the water discharge volume, and use the vacuum adaptive control algorithm to generate an adaptive vacuum treatment plan for different working conditions or determine a constant vacuum treatment plan according to the working condition requirements;

[0085] The adsorption end of the vacuum adsorption subsystem acts on the surface of the freshly mixed concrete, and is used to autonomously control the vacuum dehydration treatment process of the freshly mixed concrete under the adaptive vacuum treatment plan or the constant vacuum treatment plan;

[0086] The collection and display subsystem is used to real-time monitor the water discharge volume and the vacuum compactness of the freshly mixed concrete during the vacuum dehydration treatment process.

[0087] In one embodiment, the vacuum adsorption subsystem includes a vacuum suction pad 1, a vacuum sucker 2, a vacuum conduit 3, a vacuum degree sensor 4, a vacuum regulating valve 5, a vacuum pump 6 and a control box 7; the vacuum pump 6 is installed inside the control box 7; one end of the vacuum sucker 2 in contact with the freshly mixed concrete installs the vacuum suction pad 1 through a magnetic sealing strip, and the other end is communicated with the vacuum pump 6 through the vacuum conduit 3; both the vacuum degree sensor 4 and the vacuum regulating valve 5 are installed at one end of the vacuum conduit 3 close to the vacuum pump 6. Among them, the front end of the control box 7 is provided with a sliding door 8, the top end is provided with an anti-slip handle 9, and the side wall is provided with ventilation grilles 10. Inside the control box 7, there is a support 11, and the vacuum pump 6 is fixed on the support 11.

[0088] In another embodiment, the collection and display subsystem includes: a gas-water separation device 12, a lifting platform 13, a mass sensor 14, a nuclear density transmitter 15 and a display 16 arranged inside the control box 7; the vacuum conduit 3 includes a first conduit 301 and a second conduit 302;

[0089] Both ends of the first conduit 301 are respectively connected to the vacuum sucker 2 and the gas-water separation device 12; both ends of the second conduit 302 are respectively connected to the gas-water separation device 12 and the vacuum pump 6; among them, the open end of the gas-water separation device 12 has a rubber plug 17, and there are two through holes on the rubber plug 17, one through hole is connected to the first conduit 301, and the other through hole is connected to the second conduit 302.

[0090] The gas-water separation device 12 is installed on the surface of the lifting platform 13 and is used to continuously collect the water discharged during the vacuum process of the freshly mixed concrete;

[0091] The mass sensor 14 is installed on the lifting platform 13 and is used to real-time collect the water discharge volume of the freshly mixed concrete collected by the gas-water separation device 12;

[0092] The nuclear density emitter 15 is installed on the back of the vacuum sucker 2 and aligned with the surface of the freshly mixed concrete for real-time monitoring of the density of the freshly mixed concrete;

[0093] The display 16 is embedded on the surface of the control box 7 for real-time display of the vacuum degree, the water removal amount, and the vacuum compactness of the freshly mixed concrete.

[0094] Among them, a cesium-137 γ source is provided inside the nuclear density detector 15. The released γ rays enter the freshly mixed concrete and collide with the outer electrons of the substance atoms to generate Compton scattering. By measuring the number of γ rays after scattering, the actual density of the freshly mixed concrete can be obtained.

[0095] Specifically, the adaptive vacuum control subsystem can provide four control modes, namely: the constant vacuum degree and constant vacuum treatment time control mode, the expected vacuum depth control mode, the expected strength control mode, and the expected vacuum compactness control mode. The following is a further description of each control mode.

[0096] I. The constant vacuum degree and constant vacuum treatment time control mode is as follows: The constant vacuum degree and constant vacuum treatment time are preset, and the freshly mixed concrete is vacuum dehydrated under the constant vacuum degree. After reaching the constant vacuum treatment time, the vacuum dehydration is stopped. The following is a detailed description with a specific example:

[0097] 1. Design a precast track slab with dimensions of 5m × 2.8m × 0.2m, and the adsorption end of the vacuum adsorption subsystem is closely attached to the upper surface of the freshly mixed concrete;

[0098] 2. Connect the vacuum sucker to the gas-water separation device and the vacuum pump through a vacuum conduit. Turn on the power supply, click the "lower lifting platform" option in the display, pour out the water in the gas-water separation device, and then click the "raise lifting platform" option to return the gas-water separation device to its original position. Click the "tare" option to complete the preliminary preparation work;

[0099] 3. Select the "constant vacuum degree and constant vacuum treatment time" working mode in the adaptive vacuum system according to the working conditions. Input the required vacuum degree of 0.06 MPa, the vacuum treatment time of 10 min, and the slump of the freshly mixed concrete of 180 mm. Click the "start" option to start the vacuum dehydration work;

[0100] 4. When the set vacuum treatment time of 10 min is reached, the adaptive freshly mixed concrete vacuum dehydration device automatically stops working;

[0101] 5. Record the vacuum dehydration rate as 4.09%, and the vacuum compactness of the freshly mixed concrete measured by the nuclear density emitter is increased from 89.90% to 93.24%;

[0102] 6. After the vacuum degree drops to 0, remove the vacuum suction cup from the surface of the freshly mixed concrete and level the surface of the freshly mixed concrete;

[0103] 7. Click the "Lower the lifting platform" option on the display, pour out the water collected in the air-water separation device, and then click the "Raise the lifting platform" option to return the air-water separation device to its original position;

[0104] 8. Remove the vacuum suction cup and the vacuum conduit from the vacuum dewatering device, put them into the storage box, and after confirming that the vacuum dewatering device has stopped running, turn off the power and stop working.

[0105] II. The expected vacuum depth control mode is as follows: Under the condition of meeting the expected vacuum treatment depth, use the vacuum adaptive control algorithm to calculate the adaptive vacuum degree and the adaptive vacuum treatment time, and perform vacuum dewatering on the freshly mixed concrete at the adaptive vacuum degree. After reaching the adaptive vacuum treatment time, stop the vacuum dewatering. Specifically:

[0106] 1. Design a precast track slab with dimensions of 5m × 2.8m × 0.2m, and press the adsorption end of the vacuum adsorption subsystem tightly against the upper surface of the freshly mixed concrete;

[0107] 2. Connect the vacuum suction cup to the air-water separation device and the vacuum pump in sequence through the vacuum conduit. Turn on the power, click the "Lower the lifting platform" option on the display, pour out the water in the air-water separation device, and then click the "Raise the lifting platform" option to return the air-water separation device to its original position. Click the "Tare" option to complete the preliminary preparation work;

[0108] 3. Select the "Expected Vacuum Depth Control" working mode in the adaptive vacuum subsystem according to the working conditions, set the expected vacuum depth to 10mm, specify the vacuum degree requirement for the specified vacuum depth as 0.05MPa, the amount of concrete binder as 1321.6kg, the amount of water as 509.6kg, and the slump of the freshly mixed concrete as 180mm;

[0109] 4. The adaptive vacuum subsystem obtains the required vacuum degree of 0.0541MPa and the vacuum treatment time of 6.07min to meet the expected vacuum depth requirement through the built-in algorithm, and displays the results on the display;

[0110] 5. After confirming that the vacuum degree can meet the requirements, click the "Start" option to start the vacuum dewatering work;

[0111] 6. The air-water separation device starts to operate, observe the changes in the vacuum water removal amount and the vacuum density of the freshly mixed concrete. After reaching the set vacuum treatment time of 6.07min, the adaptive freshly mixed concrete vacuum dewatering device automatically stops working;

[0112] 7. Record the vacuum dehydration amount as 9.73 kg, the vacuum dehydration rate as 1.91%, and the vacuum density of the fresh concrete measured by the nuclear density transmitter is increased from 89.90% to 91.60%;

[0113] 8. After the vacuum degree drops to 0, remove the vacuum suction cup from the surface of the fresh concrete and level the surface of the fresh concrete;

[0114] 9. Click the "Lower the lifting platform" option on the display, pour out the water collected in the gas-water separation device, and then click the "Raise the lifting platform" option to return the gas-water separation device to its original position;

[0115] 10. Remove the vacuum suction cup and the vacuum conduit from the gas-water separation device, put them into the storage box, turn off the power, and stop working.

[0116] III. The expected strength control mode is as follows: Under the condition of meeting the expected surface strength of the concrete, use the vacuum adaptive control algorithm to calculate the adaptive vacuum degree and the expected dehydration amount. Under the adaptive vacuum degree, perform vacuum dehydration on the fresh concrete, and stop the vacuum dehydration after reaching the expected dehydration amount. Specifically:

[0117] 1. Design a precast track slab with dimensions of 5 m × 2.8 m × 0.2 m, and press the vacuum suction cup with a length of 5 m and a width of 2.8 m tightly against the surface of the fresh concrete;

[0118] 2. Connect the vacuum suction cup to the gas-water separation device and the vacuum pump in sequence through the vacuum conduit. Turn on the power, click the "Lower the lifting platform" option on the display, pour out the water in the gas-water separation device, and then click the "Raise the lifting platform" option to return the gas-water separation device to its original position. Click the "Tare" option to complete the preliminary preparation work;

[0119] 3. Select the "Expected Strength Control" working mode in the adaptive vacuum system according to the working conditions, input the amount of concrete binder as 840 kg, the amount of water as 473.2 kg, the slump of the fresh concrete as 180 mm, and the expected prepared strength as 55 MPa;

[0120] 4. The adaptive vacuum system obtains the vacuum degree of 0.045 MPa and the expected dehydration amount of 1.12 kg that meet the expected strength requirements through the built-in algorithm, and displays the results on the display;

[0121] 5. After confirming that the vacuum degree can meet the requirements, click the "Start" option to start the vacuum dehydration work;

[0122] 6. The gas-water separation device starts to operate, observe the changes in the vacuum dehydration amount and the vacuum density of the fresh concrete. When the dehydration amount reaches 1.12 kg, the adaptive fresh concrete vacuum dehydration device automatically stops working;

[0123] 7. Record that the vacuum water removal amount in the adaptive vacuum system is 1.12 kg, the vacuum dehydration rate is 0.24%, and the vacuum compactness of the fresh concrete measured by the nuclear density transmitter is increased from 89.90% to 90.17%.

[0124] 8. After the vacuum degree drops to 0, remove the vacuum suction cup from the surface of the fresh concrete and level the surface of the fresh concrete.

[0125] 9. Click the "Lower the lifting platform" option on the display, pour out the water collected in the gas-water separation device, and then click the "Raise the lifting platform" option to return the gas-water separation device to its original position.

[0126] 10. Remove the vacuum suction cup and the vacuum duct from the vacuum dehydration device, put them into the storage box, turn off the power, and stop working.

[0127] IV. The expected vacuum compactness control mode is as follows: Measure the initial density of the fresh concrete using a nuclear density transmitter, input the expected density required for the concrete, perform vacuum dehydration on the fresh concrete at a set vacuum degree, and stop the vacuum dehydration after reaching the expected density. Specifically:

[0128] 1. Design a precast track slab with dimensions of 5 m × 2.8 m × 0.2 m, and press the vacuum suction cup with a length of 5 m and a width of 2.8 m tightly against the surface of the fresh concrete.

[0129] 2. Connect the vacuum suction cup to the gas-water separation device and the vacuum pump in sequence through the vacuum duct, turn on the power, click the "Lower the lifting platform" option on the display, pour out the water in the gas-water separation device, then click the "Raise the lifting platform" option to return the gas-water separation device to its original position, and click the "Tare" option to complete the preliminary preparation work.

[0130] 3. Select the "Expected Vacuum Compactness Control" working mode in the adaptive vacuum system according to the working conditions. Input the amount of cementitious materials in the concrete as 840 kg, the amount of water as 473.2 kg, the slump of the fresh concrete as 180 mm, the required vacuum degree as 0.06 MPa, and the vacuum treatment time as 10 min. According to the nuclear density meter, the initial surface density of the fresh concrete is 2500 kg / m 3 , and the expected surface density is 2700 kg / m 3 ;

[0131] 4. The adaptive vacuum system measures the surface density of the fresh concrete in real time through the nuclear density meter and displays the result on the display.

[0132] 5. After confirming that the vacuum degree can meet the requirements, click the "Start" option to start the vacuum dehydration work.

[0133] 6. The air-water separation device starts to operate. Observe the changes in the vacuum water removal amount and vacuum density of the freshly mixed concrete. Wait until the surface density of the freshly mixed concrete reaches 2700 kg / m 3 After that, the adaptive vacuum dehydration device for freshly mixed concrete automatically stops working;

[0134] 7. Record that the vacuum water removal amount in the adaptive vacuum system is 1.69 kg, the vacuum water removal rate is 0.36%, and the vacuum density of the freshly mixed concrete measured by the nuclear density emitter is increased from 86.75% to 92.63%.

[0135] 8. After the vacuum degree drops to 0, take out the vacuum suction cup from the surface of the freshly mixed concrete and level the surface of the freshly mixed concrete;

[0136] 9. Click the "Lower the lifting platform" option on the display. After pouring out the water collected in the air-water separation device, click the "Raise the lifting platform" option to return the air-water separation device to its original position;

[0137] 10. Remove the vacuum suction cup and the vacuum conduit from the vacuum dehydration device, put them into the storage box, turn off the power supply, and stop working.

[0138] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple. For the relevant parts, reference can be made to the description in the method part.

[0139] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An adaptive vacuum dehydration method for fresh concrete, characterized in that, Including: Constructing a vacuum adaptive control algorithm for characterizing the relationship between the expected vacuum treatment depth and the vacuum degree, the relationship between the expected vacuum treatment depth and the vacuum treatment time, and the relationship between the concrete surface strength and the vacuum degree and the water removal amount; Using the vacuum adaptive control algorithm to generate an adaptive vacuum treatment plan for different working conditions or determining a constant vacuum treatment plan according to the working condition requirements; Under the adaptive vacuum treatment plan or the constant vacuum treatment plan, autonomously controlling the vacuum dehydration treatment process of fresh concrete; Real-time monitoring of the water removal amount and vacuum compactness of fresh concrete during the vacuum dehydration treatment process, and quantitatively evaluating the vacuum treatment effect.

2. The self-adaptive vacuum dehydration method for freshly mixed concrete according to claim 1, characterized in that, The constant vacuum treatment plan is: presetting a constant vacuum degree and a constant vacuum treatment time, performing vacuum dehydration on fresh concrete under the constant vacuum degree, and stopping the vacuum dehydration after reaching the constant vacuum treatment time; The adaptive vacuum treatment plan includes three types, namely the expected vacuum depth control mode, the expected strength control mode, and the expected vacuum compactness control mode; Among them, the expected vacuum depth control mode is: under the condition of meeting the expected vacuum treatment depth, calculating the adaptive vacuum degree and the adaptive vacuum treatment time by using the vacuum adaptive control algorithm, performing vacuum dehydration on fresh concrete under the adaptive vacuum degree, and stopping the vacuum dehydration after reaching the adaptive vacuum treatment time; The expected strength control mode is: based on the relationship between the water-binder ratio of concrete and the strength, under the condition of meeting the expected surface strength of the concrete, calculating the adaptive vacuum degree and the expected water removal amount by using the vacuum adaptive control algorithm, performing vacuum dehydration on fresh concrete under the adaptive vacuum degree, and stopping the vacuum dehydration after reaching the expected water removal amount; The expected vacuum compactness control mode is: measuring the initial density of fresh concrete by using a nuclear density emitter, inputting the expected density required for the concrete, performing vacuum dehydration on fresh concrete at a set vacuum degree, and stopping the vacuum dehydration after reaching the expected density.

3. An adaptive fresh concrete vacuum dewatering method according to claim 1, characterized in that, The relationship between the expected vacuum treatment depth and the vacuum degree is: Among them, P vx is the vacuum degree at the expected vacuum treatment depth; P v is the concrete surface vacuum degree; H m is the limit depth of vacuum treatment, taking 200 mm; h x is the expected vacuum treatment depth.

4. An adaptive fresh concrete vacuum dehydration method according to claim 1, characterized in that, The relationship between the expected vacuum treatment depth and the vacuum treatment time is: Among them, q0 is the initial volume of water in unit volume of concrete; α is a proportionality coefficient, and α = 100 is taken.

5. An adaptive vacuum dehydration method for freshly mixed concrete according to claim 1, characterized in that, The relationship between the concrete surface strength and the vacuum degree and the water removal amount is: Among them, W e is the mass of water after vacuum dehydration; C e is the mass of the gelling material after vacuum dehydration; U wi is the water content per unit volume before vacuum dehydration; U ci is the cement content per unit volume before vacuum dehydration; (S f / H) = 0.063 + 0.0181·logP vx (S f / H≥0) is the vacuum compaction amount of concrete per unit height; S f is the maximum compaction degree of concrete; H is the height of the concrete specimen; ρ is the density of water; β is the concrete slump correction value, which is related to the slump of the fresh concrete. When the slump of the fresh concrete is less than 50 mm, β is taken as 1.5; when the slump of the fresh concrete is 50 mm - 150 mm, β is taken as 1.2; when the slump of the fresh concrete is 150 - 200 mm, β is taken as 1; when the slump of the fresh concrete is 200 mm - 250 mm, β is taken as 0.9; when the slump of the fresh concrete is greater than 250 mm, β is taken as 0.

8.

6. An adaptive vacuum dehydration method for fresh concrete according to claim 1, characterized in that, The vacuum compactness of fresh concrete is the ratio of the measured density of fresh concrete to the expected density of fresh concrete.

7. An adaptive fresh concrete vacuum dewatering device, characterized in that, Including: An adaptive vacuum control subsystem, a vacuum adsorption subsystem, and a collection and display subsystem; The adaptive vacuum control subsystem is used to pre-embed a vacuum adaptive control algorithm for characterizing the relationship between the expected vacuum treatment depth and the vacuum degree, the relationship between the expected vacuum treatment depth and the vacuum treatment time, and the relationship between the concrete surface strength and the vacuum degree and the water removal amount, and using the vacuum adaptive control algorithm to generate an adaptive vacuum treatment plan for different working conditions or determining a constant vacuum treatment plan according to the working condition requirements; The adsorption end of the vacuum adsorption subsystem acts on the surface of the freshly mixed concrete and is used to autonomously control the vacuum dehydration process of the freshly mixed concrete under the adaptive vacuum treatment scheme or the constant vacuum treatment scheme; The collection and display subsystem is used to monitor the water removal amount and vacuum compactness of the freshly mixed concrete during the vacuum dehydration process in real time.

8. An adaptive fresh concrete vacuum dewatering device according to claim 7, characterized in that, The vacuum adsorption subsystem includes a vacuum suction pad, a vacuum sucker, a vacuum conduit, a vacuum degree sensor, a vacuum regulating valve, a vacuum pump, and a control box; the vacuum pump is installed inside the control box; one end of the vacuum sucker in contact with the freshly mixed concrete is installed with the vacuum suction pad through a magnetic seal strip, and the other end is communicated with the vacuum pump through the vacuum conduit; both the vacuum degree sensor and the vacuum regulating valve are installed at one end of the vacuum conduit close to the vacuum pump.

9. An adaptive fresh concrete vacuum dewatering device according to claim 8, characterized in that, The collection and display subsystem includes: a gas-water separation device, a lifting platform, a mass sensor, a nuclear density emitter, and a display; The lifting platform is installed inside the control box; the gas-water separation device is installed on the surface of the lifting platform and is used to continuously collect the water discharged during the vacuum process of the freshly mixed concrete; The mass sensor is installed on the lifting platform and is used to collect in real time the water removal amount of the freshly mixed concrete collected by the gas-water separation device; The nuclear density emitter is installed on the back of the vacuum sucker and is aligned with the surface of the freshly mixed concrete, and is used to monitor the density of the freshly mixed concrete in real time; The display is used to display the vacuum degree, the water removal amount, and the vacuum compactness of the freshly mixed concrete in real time, and display the corresponding operation interface for the staff to set various control parameters.

10. An adaptive fresh concrete vacuum dewatering device according to claim 9, characterized in that, A cesium-137 γ source is arranged inside the nuclear density emitter, and the released γ rays enter the freshly mixed concrete and collide with the outer electrons of the atomic substances to generate Compton scattering. By measuring the number of γ rays after scattering, the vacuum compactness of the freshly mixed concrete is obtained.

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