Concrete placing method

Abstract

The present application relates to the technical field of building construction, and specifically provides a concrete pouring method, which solves the problem of low control precision and unstable quality of concrete segregation caused by reliance on manual experience in the prior art. The method determines the maximum particle size of coarse aggregate and classifies it into A / B / C intervals, installs a distributing device and a lateral laser aggregate analyzer, and sets a variable frequency vibrator at the end of the conveying pipe. During pouring, the initial frequency f0 of the vibrator is set according to the particle size interval, the mass proportion P of the coarse aggregate is monitored in real time, when P deviates from the design value P0 by more than ±5%, the height of the distributing device is automatically reduced by 0.1-0.3m, and the vibration frequency is increased by 5-10Hz for 20-40s, the concrete temperature is simultaneously controlled by 10-18℃, and the total conveying time is less than or equal to 60min, and finally the concrete after entering the mold is vibrated. The present application is mainly used for large volume concrete pouring engineering of high-rise buildings, bridges and the like, realizes dynamic closed-loop control of segregation, and improves pouring uniformity.

Description

Technical Field

[0001] This invention relates to the field of building construction technology. More specifically, this invention relates to concrete pouring methods. Background Technology

[0002] In concrete pouring construction, the uniform distribution of coarse aggregate is crucial for structural strength and durability. Current technology primarily relies on manual experience to control the pouring process, with operators visually assessing the concrete's condition and manually adjusting the vibrator position or hose height. This method has significant drawbacks: manual operation cannot quantify the mass ratio of coarse aggregate in real time, only providing a rough perception of segregation trends. This leads to significant discrepancies in judgments among different operators regarding the same degree of segregation, resulting in inconsistent adjustment standards. Furthermore, manual response exhibits severe lag; from detecting an anomaly to executing an action, multiple stages of observation, decision-making, and action are required, taking approximately 120 seconds. During this time, about 1.5 cubic meters of segregated concrete have already flowed into the formwork, causing localized aggregate accumulation or slurry enrichment. Engineering testing data shows that the strength dispersion coefficient in manually controlled areas exceeds 15%, far higher than the 8-10% of automated construction.

[0003] The root cause of these problems lies in the lack of effective real-time monitoring methods. Laboratory sieving methods require interrupting construction and take over 10 minutes, making them unsuitable for guiding process control. Industrial camera image recognition solutions suffer from a failure rate exceeding 30% due to dust obscuring the aggregate and slurry encapsulating it, hindering practical application. Furthermore, fixed parameter control exacerbates the risk of segregation: the preset vibration frequency of 40Hz cannot accommodate differences in aggregate particle size; for example, insufficient vibration leads to uneven aggregate settling when particle size is greater than 25 mm, while over-vibration easily causes slurry to float when particle size is less than 15 mm. A fixed hose height of 1.0 meter ignores the correlation with falling kinetic energy; heights exceeding 1.2 meters exacerbate aggregate impact and accumulation, while heights below 0.5 meters restrict flow and cause blockages. Summary of the Invention

[0004] The purpose of this invention is to provide an automated and high-precision concrete pouring method, aiming to solve the problem of uneven coarse aggregate distribution caused by manual experience control in existing technologies. This method introduces a dynamic closed-loop control mechanism: first, the maximum particle size of the coarse aggregate is determined and classified into a preset range; second, a differentiated initial vibration frequency is set based on the particle size range; during the pouring process, the mass ratio P of the coarse aggregate is monitored in real time using a laser aggregate analyzer; when the P value deviates from the design value P0 by more than ±5%, an adjustment operation is automatically triggered: the height of the concrete placing device is reduced by 0.1-0.3m (ensuring an adjusted height of 0.5-1.2m) and the vibration frequency is simultaneously increased by 5-10Hz for 20-40s. At the same time, the total conveying time is strictly controlled to ≤60min and the temperature to 10-18℃ to eliminate the response lag and subjective judgment errors of manual control, significantly improving the uniformity of concrete aggregate distribution and structural strength stability. This method is suitable for large-volume concrete projects such as high-rise buildings and bridges.

[0005] This addresses the problem of uneven coarse aggregate distribution caused by concrete segregation due to manual experience-based control.

[0006] Solve the problem of concrete cracking caused by temperature fluctuations.

[0007] This addresses the issue of dust pollution interfering with the detection accuracy of laser aggregate analyzers.

[0008] Solve the problem of vibrator overload damage.

[0009] This addresses the problem of uneven vibration energy distribution reducing concrete density.

[0010] To address the measurement error in coarse aggregate proportion caused by changes in height.

[0011] To address the problem of increased concrete segregation due to flow velocity fluctuations.

[0012] This addresses the issue of uneven pouring surfaces caused by localized buildup.

[0013] To solve the problem of concrete surface defects caused by air bubble aggregation.

[0014] To address the aforementioned problems and achieve the objectives and other advantages of this invention, a concrete pouring method is provided, comprising the following steps:

[0015] Determine the maximum particle size d of the coarse aggregate;

[0016] When preparing fresh concrete at a concrete mixing plant, the coarse aggregate used has a particle size of 5-40mm. Record the mass ratio of coarse aggregate P0 in the design mix proportion.

[0017] Based on the maximum particle size d of the coarse aggregate, determine its particle size range: Range A: 5mm≤d<15mm; Range B: 15mm≤d<25mm; Range C: 25mm≤d≤40mm;

[0018] An adjustable-height concrete placing device is installed above the formwork of the structure to be poured. The placing device includes a rigid conveying pipe and a detachable hose connected to the end of the rigid conveying pipe.

[0019] Install a laser aggregate analyzer on the side of the hose outlet;

[0020] A variable frequency vibrator is installed on the outer wall of the connection between the end of the rigid conveying pipe and the flexible hose.

[0021] Freshly mixed concrete is pumped out through rigid delivery pipes and flexible hoses via concrete pumps.

[0022] The initial operating frequency f0 of the variable frequency vibrator is set according to the particle size range of the coarse aggregate: 35-40Hz for range A; 40-45Hz for range B; and 45-50Hz for range C.

[0023] Start the variable frequency vibrator and apply radial vibration at f0;

[0024] The following controls shall be implemented during the concrete pouring process:

[0025] The mass ratio P of coarse aggregate in the flowing concrete is obtained in real time using a laser aggregate analyzer. When the P value deviates from the P0 value by more than ±5%, the height and frequency adjustment operation is triggered.

[0026] The height of the concrete placing device is automatically adjusted to reduce the vertical height between the outlet end of the hose and the current pouring surface by 0.1-0.3m, and to ensure that the adjusted height is between 0.5-1.2m.

[0027] Increase the operating frequency of the variable frequency vibrator by 5-10Hz based on f0 and run it continuously for 20-40 seconds;

[0028] Control the output rate of the concrete pump so that the total time from when the fresh concrete leaves the batching plant to when it falls into the formwork through the hose outlet is ≤60 minutes, and the temperature is maintained at 10-18℃.

[0029] After the concrete is poured into the formwork, it is vibrated with an immersion vibrator. The vibration depth is 50-70cm, the vibration duration at a single point is 15-25s, and the distance between adjacent vibration points is ≤60cm.

[0030] Preferably, in the concrete pouring method, at the concrete mixing plant, a precooling system is used to reduce the temperature of coarse aggregate to 8-15°C, and then it is mixed with cement, admixtures, additives and mixing water in a mixer to prepare fresh concrete.

[0031] During the concrete pouring process, the following controls are also implemented:

[0032] Use a temperature sensor inserted into the freshly mixed concrete to monitor the internal temperature of the concrete in real time;

[0033] When the real-time monitored internal temperature of the concrete reaches 18℃, a cooling command is sent to the mixing plant.

[0034] After receiving the cooling command, the mixing plant starts the pre-cooling system to further reduce the target temperature of the coarse aggregate to be added to the next batch of mixing to 5-10℃.

[0035] Preferably, in the concrete pouring method, a laser aggregate analyzer is installed 10-15cm from the outlet of the flexible hose, and the central axis of the detection window of the laser aggregate analyzer is at an elevation angle of 20-25° to the vertical falling direction of the concrete.

[0036] A ring-shaped compressed air nozzle is integrated circumferentially into the detection window of the laser aggregate analyzer;

[0037] During the concrete pouring process, the following controls are also implemented:

[0038] When the difference between the highest and lowest P-values ​​detected three times consecutively by the laser aggregate analyzer exceeds 6% of the average of the three values, a cleaning operation is initiated.

[0039] Activate the annular compressed air nozzle and inject compressed air at a pressure of 0.35-0.45 MPa for 4-6 seconds;

[0040] After the cleaning operation is completed, obtain the P value again;

[0041] If the deviation between the re-acquired P-value and the P-value of the last test before the cleaning operation exceeds ±1.5%, the cleaning operation is repeated.

[0042] If, after two repeated cleaning operations, the deviation between the newly acquired P-value and the P-value detected before the last cleaning operation still exceeds ±1.5%, an alarm will be triggered and pouring will be suspended.

[0043] Preferably, in the concrete pouring method, a triaxial vibration acceleration sensor is installed on the outer wall of the rigid conveying pipe 5-10cm above the connection between the end of the rigid conveying pipe and the flexible hose.

[0044] Install a temperature sensor at the center point of the non-heat-dissipating area of ​​the variable frequency vibrator motor housing;

[0045] During the concrete pouring process, the following controls are also implemented:

[0046] The vibration acceleration amplitude A monitored by the triaxial vibration accelerometer and the surface temperature T monitored by the temperature sensor are acquired in real time.

[0047] When any of the following conditions are met:

[0048] a) A>15m / s 2 And continuously for 10 seconds;

[0049] b) T > 65℃;

[0050] The operating frequency of the variable frequency vibrator is automatically reduced by 4±0.5Hz from the current operating frequency;

[0051] After reducing the frequency, follow these steps:

[0052] If the value of A drops to ≤10m / s within 30s 2 If the T value is ≤60℃, the operating frequency will be restored to the frequency value before the frequency reduction operation.

[0053] If either the A value or the T value fails to meet the standard, the reduced operating frequency will be maintained.

[0054] When the cumulative frequency reduction operation time reaches 90 seconds, a shutdown alarm is triggered.

[0055] Preferably, in the concrete pouring method, the following vibration energy optimization and control steps are added during the concrete pouring process:

[0056] Within the first 5 minutes after the start of concrete pouring, the raw signal of the concrete scattered light was collected every 30 seconds for 10 seconds using a laser aggregate analyzer.

[0057] Perform spectral analysis on each 10-second signal acquisition and calculate the total signal energy value of each acquisition signal within the frequency range of 100-500Hz.

[0058] Take the arithmetic mean of the total signal energy values ​​calculated independently above 10 times, and record it as the baseline energy value E0;

[0059] Starting from the 5th minute after pouring begins, a new 10-second raw signal of the concrete scattered light is collected every 10 seconds using a laser aggregate analyzer, and the total signal energy value of this newly collected signal in the frequency range of 100-500Hz is calculated and recorded as the current energy value E.

[0060] When the current energy value E obtained three times consecutively is greater than 1.2 times the baseline energy value E0, perform the following operations:

[0061] The variable frequency vibrator is controlled with f0 as the center frequency and the output frequency is continuously adjusted according to the sine waveform. The frequency fluctuation range is ±3Hz of the center frequency. Each complete cycle from the center frequency to the peak value, to the trough value, and back to the center frequency takes 6 seconds.

[0062] Maintain this sinusoidal waveform frequency adjustment mode for 25 seconds;

[0063] After the operation is completed, the frequency converter will automatically return to the constant vibration mode at f0.

[0064] Preferably, in the concrete pouring method, the following controls are also performed during the concrete pouring process:

[0065] 1) Pre-store the compensation coefficient table, which contains the compensation coefficients corresponding to different coarse aggregate particle size ranges and height variations ΔH;

[0066] 2) When the height of the fabric assembly is adjusted:

[0067] Calculate the height change ΔH between the current height H and the initial installation height H0, where ΔH = H0 - H;

[0068] Based on the particle size range and ΔH value of the coarse aggregate, consult the compensation coefficient table to obtain the basic compensation coefficient K;

[0069] 3) Obtain the current operating frequency f of the variable frequency vibrator, and calculate the absolute value of the difference between f and f0, |△f|, where |△f| = |f - f0|;

[0070] If |△f|≤3Hz, then keep the basic compensation coefficient K unchanged;

[0071] If 3Hz < |Δf| ≤ 6Hz, then increase the basic compensation coefficient K by 0.03;

[0072] If |△f|>6Hz, then increase the basic compensation coefficient K by 0.06;

[0073] 4) Multiply the P value measured by the laser aggregate analyzer by the compensation coefficient K to obtain the calibration value P. cal ;

[0074] 5) When P is detected cal When the deviation from P0 exceeds ±5%, the height and frequency adjustment operation is triggered.

[0075] Preferably, in the concrete pouring method, a flow rate sensor is installed at the outlet of the hose;

[0076] When the altitude and frequency adjustment operations are triggered, the following controls are executed:

[0077] The initial concrete flow velocity is obtained by a flow velocity sensor. The initial concrete flow velocity is the average flow velocity before the adjustment operation is triggered.

[0078] The target flow velocity range is set to 0.8-1.2 times the initial concrete flow velocity;

[0079] Real-time monitoring of concrete flow velocity using flow velocity sensors;

[0080] When the concrete flow rate is greater than the upper limit of the target flow rate range, the concrete flow rate is reduced to bring the concrete flow rate back to the target flow rate range.

[0081] When the concrete flow velocity is less than the lower limit of the target flow velocity range, the concrete flow velocity is brought back to the target flow velocity range by increasing the output rate of the concrete pump.

[0082] Repeat the above flow rate monitoring and pump output rate adjustment operations until the P value detected by the laser aggregate analyzer stabilizes within the range of P0±5%.

[0083] When adjusting the output rate of the concrete pump, ensure that the total time from when the freshly mixed concrete leaves the mixing plant to when it falls into the formwork through the hose outlet is ≤60 minutes.

[0084] Preferably, in the concrete pouring method, after triggering the height and frequency adjustment operation, the following movement control is executed:

[0085] The fabric control device performs two-dimensional reciprocating movement in the horizontal plane. The starting point of the movement is the instantaneous position at the time of the trigger operation. The movement process executes the following steps in sequence:

[0086] Move a distance L along the positive X-axis of the preset horizontal rectangular coordinate system x = 0.75 times the inner diameter of the hose outlet;

[0087] Move a distance L along the positive Y-axis y = 0.5 times the inner diameter of the hose outlet;

[0088] Move a distance L along the negative X-axis x ;

[0089] Move a distance L along the negative Y-axis y ;

[0090] The moving speed is 0.1-0.3 m / s, and the continuous moving time is the same as the continuous running time of the frequency converter after increasing the frequency.

[0091] Preferably, in the concrete pouring method, the following air bubble control step is added during the concrete pouring process:

[0092] The laser aggregate analyzer takes three consecutive samples with an interval of ≥1s between each sample, measuring the mass proportions of coarse aggregate P1, P2, and P3. The fluctuation range ΔP of P1, P2, and P3 is calculated as: ΔP = max(P1, P2, P3) − min(P1, P2, P3). When ΔP ≤ 1%, bubble control is executed.

[0093] Reduce the operating frequency of the variable frequency vibrator by 3-5Hz based on f0;

[0094] The height of the concrete placing device is adjusted synchronously to control the vertical height between the outlet end of the hose and the pouring surface at 0.5-0.6m.

[0095] Maintain this state while pouring for 2-3 meters. 3 Concrete;

[0096] Once completed, restore the operating frequency and height value to the state before the bubble control operation;

[0097] After every five bubble control operations, perform bubble detection and parameter adjustment:

[0098] Level the pouring surface by 1m. 2 The area is covered with a transparent polyethylene film;

[0099] After standing for 10 minutes, count the number N of bubbles with a diameter greater than 2 mm.

[0100] If N > 15, the frequency reduction of subsequent bubble control operations will be increased by 1 Hz.

[0101] If N≤8, then the subsequent frequency reduction will be reduced by 1Hz;

[0102] If 8 < N ≤ 15, then the original frequency reduction rate remains unchanged.

[0103] The present invention has at least the following beneficial effects:

[0104] This invention significantly improves the uniformity of concrete aggregate distribution and reduces strength dispersion caused by segregation by dividing the aggregate into intervals based on the maximum particle size and setting differentiated initial vibration frequencies, combined with real-time laser monitoring of the coarse aggregate ratio and closed-loop control of automatic adjustment of height and frequency.

[0105] This invention effectively suppresses the internal temperature rise of concrete, reduces the risk of temperature difference cracks, and ensures the durability of large-volume concrete structures by pre-cooling coarse aggregate and triggering a dynamic cooling mechanism based on a temperature threshold.

[0106] This invention employs a side-mounted, elevation-angled laser aggregate analyzer and a compressed air self-cleaning system to eliminate interference from dust and slurry adhesion, ensuring reduced detection accuracy deviation and improving the reliability of segregation judgment.

[0107] This invention reduces equipment failure rate and balances construction continuity with equipment safety by real-time monitoring of vibration acceleration and temperature dual thresholds, automatic frequency reduction protection, and cumulative operation time-limited shutdown mechanism.

[0108] This invention identifies concrete rheological anomalies by monitoring scattered light energy, triggers sinusoidal frequency modulation to break the resonance state, improves concrete density, and optimizes vibration energy transfer efficiency.

[0109] This invention utilizes a compensation coefficient to dynamically calibrate measurement errors caused by height changes and frequency shifts, thereby improving the accuracy of segregation determination and avoiding accidental triggering of adjustment operations.

[0110] This invention performs closed-loop flow rate control after segregation adjustment, limiting the flow rate fluctuation range to ±20% of the baseline value, suppressing secondary segregation and strictly ensuring that the total conveying time is ≤60min, thus maintaining the workability of the material.

[0111] This invention initiates two-dimensional forward reciprocating movement after triggering the adjustment operation, expands the material distribution range and matches the spatiotemporal matching of vibration strengthening, eliminates local aggregate accumulation, and improves the flatness of the pouring surface.

[0112] This invention identifies high-risk periods for bubble formation based on the characteristics of coarse aggregate ratio fluctuations, automatically reduces the frequency and height of bubble merging and generation, and dynamically optimizes parameters through periodic bubble quantity statistics to reduce surface defects.

[0113] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0114] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0115] This invention provides a concrete pouring method, comprising the following steps:

[0116] Determine the maximum particle size d of the coarse aggregate;

[0117] When preparing fresh concrete at a concrete mixing plant, the coarse aggregate used has a particle size of 5-40mm. Record the mass ratio of coarse aggregate P0 in the design mix proportion.

[0118] Based on the maximum particle size d of the coarse aggregate, determine its particle size range: Range A: 5mm≤d<15mm; Range B: 15mm≤d<25mm; Range C: 25mm≤d≤40mm;

[0119] An adjustable-height concrete placing device is installed above the formwork of the structure to be poured. The placing device includes a rigid conveying pipe and a detachable hose connected to the end of the rigid conveying pipe.

[0120] A laser aggregate analyzer is installed on the side of the hose outlet. The principle of the laser aggregate analyzer to monitor the mass ratio P of coarse aggregate in real time on the side of the hose outlet is as follows: a 1550nm near-infrared laser is used to penetrate the slurry layer on the concrete surface. Based on the difference in reflection intensity between coarse aggregate (reflectivity 60-75%) and slurry (reflectivity <25%), the scattered light signal is captured by a high-speed sensor and the proportion of bright pixels is calculated, and the P value is dynamically output (accuracy ±1.8%). This detection accuracy ensures the reliability of the ±5% deviation trigger condition, and the measured engineering deviation is ≤1.0% (e.g., 42.3% laboratory value corresponds to 43.1% monitoring value).

[0121] A variable frequency vibrator is installed on the outer wall of the connection between the end of the rigid conveying pipe and the flexible hose.

[0122] Freshly mixed concrete is pumped out through rigid delivery pipes and flexible hoses via concrete pumps.

[0123] The initial operating frequency f0 of the variable frequency vibrator is set according to the particle size range of the coarse aggregate: 35-40Hz for range A; 40-45Hz for range B; and 45-50Hz for range C.

[0124] Start the variable frequency vibrator and apply radial vibration at f0;

[0125] The following controls shall be implemented during the concrete pouring process:

[0126] The mass ratio P of coarse aggregate in the flowing concrete is obtained in real time using a laser aggregate analyzer. When the P value deviates from the P0 value by more than ±5%, the height and frequency adjustment operation is triggered.

[0127] The height of the concrete placing device is automatically adjusted to reduce the vertical height between the outlet end of the hose and the current pouring surface by 0.1-0.3m, and to ensure that the adjusted height is between 0.5-1.2m.

[0128] Increase the operating frequency of the variable frequency vibrator by 5-10Hz based on f0 and run it continuously for 20-40 seconds;

[0129] Control the output rate of the concrete pump so that the total time from when the fresh concrete leaves the batching plant to when it falls into the formwork through the hose outlet is ≤60 minutes, and the temperature is maintained at 10-18℃.

[0130] After the concrete is poured into the formwork, it should be compacted using an immersion vibrator. The compaction depth should be 50-70cm, the duration of single-point compaction should be 15-25s, and the distance between adjacent compaction points should be ≤60cm, until the following conditions are met:

[0131] a) Cementation on the concrete surface;

[0132] b) The concrete did not sink significantly after the vibrator was slowly pulled out;

[0133] c) No bubbles continue to escape.

[0134] In concrete pouring, the conventional method uses a fixed vibration frequency of 40Hz and a manually controlled hose height of 1.0m. The operator visually assesses the segregation state and manually adjusts the frequency. This method has significant drawbacks: the fixed frequency cannot accommodate differences in coarse aggregate size; for example, with 30mm aggregate, 40Hz vibration is insufficient, leading to uneven aggregate settling; with 10mm aggregate, the same frequency easily causes slurry to float. Furthermore, the manual response delay is approximately 120s, covering a period of about 1.5m. 3 Segregated concrete has already flowed into the formwork. Even with subsequent manual vibration, the excessive amount of pre-segregated concrete makes it difficult to eliminate the problems of uneven aggregate distribution and strength dispersion.

[0135] This embodiment addresses the above-mentioned problems by performing the following steps: First, the maximum particle size d of the coarse aggregate is measured and classified into intervals A (5mm ≤ d < 15mm), B (15mm ≤ d < 25mm), or C (25mm ≤ d ≤ 40mm). This classification clarifies the vibration parameter adaptation benchmark to solve the fixed frequency failure problem. A height-adjustable material distribution device is installed, and a laser aggregate analyzer is installed on the side of the hose outlet to quantify the mass ratio P of the coarse aggregate in real time, replacing the subjectivity of manual visual inspection; a variable frequency vibrator is installed at the end of the conveying pipe to provide adjustable vibration energy. The initial frequency f0 is set according to the particle size intervals: 35-40Hz for interval A, 40-45Hz for interval B, and 45-50Hz for interval C. This differentiated frequency matching ensures effective vibration of aggregates of different particle sizes. During pouring, the P-value is monitored in real time using a laser aggregate analyzer. When the P-value deviates from the design value P0 by more than ±5%, automatic adjustment is triggered: the hose height is reduced by 0.1-0.3m (adjusted height 0.5-1.2m) to shorten the falling distance and reduce aggregate segregation kinetic energy; simultaneously, the vibration frequency is increased by 5-10Hz from f0 for 20-40s to enhance compaction force and promote uniform aggregate distribution. This closed-loop control eliminates the delay of manual response. The concrete temperature is controlled at 10-18℃ and the total conveying time is ≤60min throughout the process to ensure material workability and prevent segregation deterioration. After completing the above operations, the concrete placement area still needs to undergo conventional vibration: using an immersion vibrator with parameters of 50-70cm depth, single-point duration of 15-25s, and spacing ≤60cm, to ensure the final concrete density is ≥94%.

[0136] Example 1

[0137] For the pouring of the raft foundation of a high-rise building, the maximum coarse aggregate size was 32mm, falling within range C. The initial frequency was set at 48Hz, and the P-value fluctuation range monitored by laser was P0±3.8%. An immersion vibrator was used to compact the concrete before placement, with a vibration depth of 60cm, a single-point vibration duration of 20s, and a spacing of 50cm between adjacent points. After final setting, the following results were obtained: strength dispersion coefficient 9.2%, segregation area percentage 6.5%, and core density 94.1%.

[0138] Example 2

[0139] For the pouring of a bridge pier, the maximum coarse aggregate size was 12mm, falling within interval A. The initial frequency was set at 38Hz. During pouring, the P-value suddenly increased to P0+6.1%. The system automatically lowered its height by 0.3m and raised the frequency to 44Hz for 25 seconds. Within 30 seconds, the P-value returned to the range of P0±4%. An immersion vibrator was used to compact the concrete before placement, with a compaction depth of 60cm, a single-point compaction time of 20 seconds, and a spacing of 50cm between adjacent points. After final setting, the segregation area was 5.1%, and the core sample density was 95.3%.

[0140] Comparative Example 1

[0141] Similar to Example 1, a fixed frequency of 40Hz was used. When the aggregate size was 32mm, vibration was insufficient, resulting in a coarse aggregate proportion in the lower part of the cast body that was 8.7% lower than the design value. Manual vibration was applied during placement of the formwork (parameters same as Example 1), with a vibration depth of 60cm, a single-point vibration duration of 20s, and a spacing of 50cm between adjacent points. After final setting, the strength dispersion coefficient was 19.5%, the segregation area ratio was 14.8%, and the density of local honeycomb areas was only 82%.

[0142] Comparative Example 2

[0143] Similar to Example 2, under the manual intervention mode, it was found that the height adjustment was completed in 115 seconds after segregation. During this period, 1.8m of segregated concrete flowed in. 3 The material was manually vibrated in the mold (parameters same as in Example 1), with a vibration depth of 60cm, a single-point vibration duration of 20s, and a spacing of 50cm between adjacent points. After final setting, the segregation area reached 11.3%, the density of the slurry enrichment area was 85%, and the density of the aggregate accumulation area was 89%.

[0144] Results: In Example 1, the segregation area ratio was 6.5% when the frequency of interval C was 48Hz, while in Comparative Example 1, the segregation area ratio was 14.8% when the frequency was fixed at 40Hz, resulting in a 56% improvement in aggregate distribution uniformity. The core density of Example 1 was 94.1%, while the density of the local honeycomb area in Comparative Example 1 was only 82%, resulting in a 14.6% improvement in structural reliability.

[0145] Example 2: Automatic adjustment of 0.3m³ of segregated concrete within 30 seconds. 3 Comparative Example 2: Manual adjustment took 115 seconds, resulting in 1.8 m³ of segregated concrete. 3 Automatic response efficiency is improved by 83%.

[0146] Example 2 showed a core density of 95.3%, while Comparative Example 2 showed a slurry-rich zone density of 85%, resulting in an overall density increase of 12.1%. In another embodiment, the concrete pouring method involves using a pre-cooling system at the concrete mixing plant to lower the temperature of the coarse aggregate to 8-15°C, and then mixing it with cement, admixtures, additives, and mixing water in a mixer to prepare fresh concrete.

[0147] During the concrete pouring process, the following controls are also implemented:

[0148] Use a temperature sensor inserted into the freshly mixed concrete to monitor the internal temperature of the concrete in real time;

[0149] When the real-time monitored internal temperature of the concrete reaches 18℃, a cooling command is sent to the mixing plant.

[0150] After receiving the cooling command, the mixing plant starts the pre-cooling system to further reduce the target temperature of the coarse aggregate to be added to the next batch of mixing to 5-10℃.

[0151] When preparing fresh concrete at a concrete batching plant, the conventional method involves directly mixing coarse aggregates at ambient temperature (25-35℃), with temperature passively controlled only through the insulation layer during pouring. This approach carries the risk of temperature runaway: high-temperature aggregates can cause the initial temperature of the mixture to exceed 22℃, and the internal temperature after pouring can easily exceed 25℃, leading to temperature difference cracks.

[0152] This implementation addresses the aforementioned issues by performing the following steps: A pre-cooling system at the concrete mixing plant dynamically reduces the temperature of the coarse aggregate to 8-15℃, ensuring its thermal stability. The pre-cooled coarse aggregate is then simultaneously added to the mixer along with cement, admixtures, additives, and mixing water to prepare fresh concrete with a controllable initial temperature. During pouring, a temperature sensor is inserted into the fresh concrete to monitor internal temperature changes in real time. When the monitored temperature reaches a critical value of 18℃, a cooling command is automatically sent to the mixing plant. Upon receiving the command, the mixing plant activates the pre-cooling system to further reduce the target temperature of the next batch of coarse aggregate to be mixed to 5-10℃, forming a dynamic temperature suppression mechanism. The entire process combines coarse aggregate ratio control with temperature-coordinated constraints to achieve dual risk control against segregation and thermal cracking.

[0153] In another embodiment, in the concrete pouring method, a laser aggregate analyzer is installed 10-15cm to the side of the hose outlet, and the central axis of the detection window of the laser aggregate analyzer is at an elevation angle of 20-25° to the vertical falling direction of the concrete.

[0154] A ring-shaped compressed air nozzle is integrated circumferentially into the detection window of the laser aggregate analyzer;

[0155] During the concrete pouring process, the following controls are also implemented:

[0156] When the difference between the highest and lowest P-values ​​detected three times consecutively by the laser aggregate analyzer exceeds 6% of the average of the three values, a cleaning operation is initiated.

[0157] Activate the annular compressed air nozzle and inject compressed air at a pressure of 0.35-0.45 MPa for 4-6 seconds;

[0158] After the cleaning operation is completed, obtain the P value again;

[0159] If the deviation between the re-acquired P-value and the P-value of the last test before the cleaning operation exceeds ±1.5%, the cleaning operation is repeated.

[0160] If, after two repeated cleaning operations, the deviation between the newly acquired P-value and the P-value detected before the last cleaning operation still exceeds ±1.5%, an alarm will be triggered and pouring will be suspended.

[0161] In conventional concrete pouring methods, the laser aggregate analyzer is directly installed at the side of the hose outlet, with the detection window horizontal. Dust and slurry splashes generated by falling concrete easily adhere to the detection window, causing signal distortion, and there is no active cleaning mechanism.

[0162] This implementation addresses the aforementioned issues by performing the following steps: A laser aggregate analyzer is installed 10-15cm to the side of the hose outlet, with its detection window's central axis forming a 20-25° angle with the vertical falling direction of the concrete, avoiding the main falling trajectory and reducing direct slurry contamination. A ring-shaped compressed air nozzle is integrated around the detection window, with the nozzle outlet pointing perpendicularly to the window surface. During pouring, the laser aggregate analyzer continuously measures the coarse aggregate proportion (P-value) three times. If the difference between the highest and lowest values ​​exceeds 6% of the average of the three values, it is determined that dust interference is causing signal abnormalities. The ring-shaped compressed air nozzle is immediately activated, spraying compressed air at 0.35-0.45MPa for 4-6 seconds to remove attached contaminants. After cleaning, the P-value is re-acquired. If the deviation from the last detection value before cleaning exceeds ±1.5%, the spraying operation is repeated. If the deviation still exceeds ±1.5% after two repetitions, an alarm is triggered, pouring is paused, and manual intervention is requested.

[0163] Laser particle size analysis technology has been successfully applied in mining crushing production lines and agricultural particle sorting. It uses 1550nm near-infrared laser light to identify the reflection characteristics of moving particles in dust concentrations >100mg / m³. 3 It maintains an accuracy of ±1.5% even in challenging environments. However, concrete pouring presents unique challenges such as aggregate encapsulation by slurry and high-frequency mechanical vibration, and directly transplanting existing equipment would lead to contamination of the detection window and signal distortion.

[0164] This solution adopts a lateral 20-25° elevation angle installation method, drawing on the oblique detection scheme for material monitoring of mining conveyor belts. However, in view of the adhesion characteristics of concrete slurry, an additional annular compressed air nozzle is added. Its 0.35-0.45MPa injection parameters are determined based on building materials laboratory tests: when the pressure is <0.35MPa, the cement slurry film cannot be peeled off, and when the pressure is >0.45MPa, it interferes with the falling trajectory of the concrete.

[0165] According to actual tests conducted at a commercial concrete mixing plant, under the same dust conditions, the industrial camera image recognition had a misjudgment rate of 31.5% due to slurry reflection, while the laser analysis method in this case, after optimization of elevation angle and self-cleaning, reduced the misjudgment rate to 4.2% (compared with the manual sieving method).

[0166] In another embodiment, in the concrete pouring method, a triaxial vibration acceleration sensor is installed on the outer wall of the rigid conveying pipe 5-10cm above the connection between the end of the rigid conveying pipe and the flexible hose.

[0167] Install a temperature sensor at the center point of the non-heat-dissipating area of ​​the variable frequency vibrator motor housing;

[0168] During the concrete pouring process, the following controls are also implemented:

[0169] The vibration acceleration amplitude A monitored by the triaxial vibration accelerometer and the surface temperature T monitored by the temperature sensor are acquired in real time.

[0170] When any of the following conditions are met:

[0171] a) A>15m / s 2 And continuously for 10 seconds;

[0172] b) T > 65℃;

[0173] The operating frequency of the variable frequency vibrator is automatically reduced by 4±0.5Hz from the current operating frequency;

[0174] After reducing the frequency, follow these steps:

[0175] If the value of A drops to ≤10m / s within 30s 2 If the T value is ≤60℃, the operating frequency will be restored to the frequency value before the frequency reduction operation.

[0176] If either the A value or the T value fails to meet the standard, the reduced operating frequency will be maintained.

[0177] When the cumulative frequency reduction operation time reaches 90 seconds, a shutdown alarm is triggered.

[0178] In conventional concrete pouring methods, variable frequency vibrators rely solely on manual observation of their operating status, lacking real-time monitoring and protection mechanisms, making them prone to damage due to vibration overload or temperature rise.

[0179] To prevent equipment failure, this implementation method installs a triaxial vibration acceleration sensor on the outer wall 5-10cm above the connection point between the rigid conveying pipe and the flexible hose to accurately capture the vibration energy transfer state of the rigid pipe, avoiding interference from the hose's damping. A temperature sensor is installed at the center point of the non-heat-dissipating area of ​​the variable frequency vibrator motor housing to obtain accurate temperature rise data, avoiding the influence of the heat sink. The vibration acceleration amplitude A and surface temperature T are acquired in real time. When A > 15m / s², [further details are needed]. 2 If the operating frequency is continuously reduced by 4±0.5Hz for 10 seconds or when T>65℃, the operating frequency will be reduced to suppress the risk of overload; if A≤10m / s within 30 seconds after frequency reduction, the operating frequency will be reduced. 2 Furthermore, if T≤60℃, the original frequency is restored to ensure construction continuity; otherwise, the frequency is reduced to prevent damage from worsening. When the cumulative frequency reduction operation reaches 90s, a shutdown alarm is triggered to avoid permanent damage to the equipment, thus balancing protection needs with construction efficiency.

[0180] Example 3

[0181] The raft foundation of a high-rise building used coarse aggregate with a maximum particle size of 35mm in section C. The initial frequency was set to 48Hz, and the laser monitoring showed a P-value fluctuation range of P0±4.2%. During pouring, an accelerometer detected A = 16.5m / s². 2 After 11 seconds, the system automatically reduced its frequency to 44Hz. Within 25 seconds, the A value dropped to 9.8m / s. 2 The T value stabilized at 59℃, and the frequency recovered to 48Hz. The cumulative frequency reduction time was 45s, which did not reach the 90s threshold. An immersion vibrator was used to vibrate the concrete before it was poured, with a vibration depth of 60cm, a single point vibration duration of 20s, and a spacing of 50cm between adjacent points. The equipment completed the pouring without any faults. After final setting, the core sample was taken and the density was tested to be 94.6%.

[0182] Comparative Example 3

[0183] Similar to Example 3, the project used coarse aggregate with a maximum particle size of 35mm in section C and set an initial frequency of 48Hz. No acceleration or temperature sensors were installed. At 32 minutes of pouring, the vibrator experienced a sudden abnormal vibration, requiring a manual delay in response. At 38 minutes, the motor burned out and the machine stopped; replacing the components took 4 hours. Vibration was only applied to the concrete already poured before the failure (parameters same as Example 3), with a vibration depth of 60cm, a single-point duration of 20s, and a spacing of 50cm between adjacent points. After final setting, the density of the section poured before the failure was 83.7%, indicating that the affected area was not properly formed.

[0184] Results: Example 3 avoids mechanical damage by triggering frequency reduction through acceleration threshold; Comparative Example 3 suffers equipment damage due to lack of monitoring.

[0185] Example 3: The cumulative frequency reduction for 45 seconds did not reach the 90-second threshold, ensuring continuous construction; Comparative Example 3: A fault caused a 4-hour work stoppage.

[0186] Example 3 showed a core density of 94.6%, while Comparative Example 3 showed a density of only 83.7% in the section before the failure, resulting in a 13.0% improvement in structural reliability.

[0187] In another embodiment, the concrete pouring method includes the following vibration energy optimization and control steps during the concrete pouring process:

[0188] Within the first 5 minutes after the start of concrete pouring, the raw signal of the concrete scattered light was collected every 30 seconds for 10 seconds using a laser aggregate analyzer.

[0189] Perform spectral analysis on each 10-second signal acquisition and calculate the total signal energy value of each acquisition signal within the frequency range of 100-500Hz.

[0190] Take the arithmetic mean of the total signal energy values ​​calculated independently above 10 times, and record it as the baseline energy value E0;

[0191] Starting from the 5th minute after pouring begins, a new 10-second raw signal of the concrete scattered light is collected every 10 seconds using a laser aggregate analyzer, and the total signal energy value of this newly collected signal in the frequency range of 100-500Hz is calculated and recorded as the current energy value E.

[0192] When the current energy value E obtained three times consecutively is greater than 1.2 times the baseline energy value E0, perform the following operations:

[0193] The variable frequency vibrator is controlled with f0 as the center frequency and the output frequency is continuously adjusted according to the sine waveform. The frequency fluctuation range is ±3Hz of the center frequency. Each complete cycle from the center frequency to the peak value, to the trough value, and back to the center frequency takes 6 seconds.

[0194] Maintain this sinusoidal waveform frequency adjustment mode for 25 seconds;

[0195] After the operation is completed, the frequency converter will automatically return to the constant vibration mode at f0.

[0196] In conventional concrete pouring methods, variable frequency vibrators operate at a fixed frequency f0, which cannot adaptively optimize energy distribution based on the rheological properties of concrete.

[0197] To optimize vibration energy distribution, this implementation method involves acquiring a 10-second raw signal of scattered concrete light every 30 seconds during the first 5 minutes of pouring using a laser aggregate analyzer. After each acquisition, the total signal energy within the 10-second frequency range of 100-500Hz is calculated, and the arithmetic mean of 10 calculations is taken as the baseline energy value E0. Starting from the 5th minute, a newly generated 10-second raw signal of scattered concrete light is acquired every 10 seconds, and the current energy value E within the 100-500Hz range is calculated. When the E value is greater than 1.2 times E0 for three consecutive times, the variable frequency vibrator is controlled to continuously adjust the output frequency in a sinusoidal waveform with f0 as the center frequency. The frequency fluctuation amplitude is ±3Hz of the center frequency, and each complete cycle from the center frequency to the peak value, down to the trough value, and back to the center frequency takes 6 seconds. This sinusoidal waveform adjustment mode is maintained for 25 seconds before resuming the constant f0 vibration mode. The periodic frequency change breaks the resonance state of the concrete and optimizes energy transfer efficiency.

[0198] Example 4

[0199] The foundation slab of a high-rise building used coarse aggregate with a maximum particle size of 20mm in section B. The initial frequency was set to 42Hz. For the first 5 minutes of pouring, scattered light signals were collected for 10 seconds every 30 seconds, and the baseline energy value E0 = 1520 units was calculated. At the 8th minute, the current energy values ​​E0 were 1830, 1845, and 1860 units respectively (all greater than 1520 × 1.2 = 1824 units). The system immediately started sinusoidal frequency modulation: centered at 42Hz, the frequency fluctuated sinusoidally between 39-45Hz, completing a full cycle every 6 seconds (rising from the center frequency to the peak, falling to the trough, and returning to the center frequency), continuing for 25 seconds before resuming constant frequency operation at 42Hz. An immersion vibrator was used to compact the concrete, with a compaction depth of 60cm, a single-point compaction time of 20 seconds, and a spacing of 50cm between adjacent points. After final setting, core samples were taken to test the compaction density at 94.2%.

[0200] Comparative Example 4

[0201] Similar to Example 4, the maximum particle size of the coarse aggregate in section B was 20mm, and the initial frequency was set to 42Hz. Vibration energy optimization was disabled. At the 8-minute mark, the energy value also exceeded the baseline value by 20%, but no frequency adjustment was performed. Manual compaction was carried out (parameters same as Example 4), with a compaction depth of 60cm, a single-point duration of 20s, and a spacing of 50cm between adjacent points. After final setting, core samples taken from the same location showed a density of 86.5%, with locally visible honeycomb-like pores.

[0202] Results: Example 4 broke the resonance of concrete by using sine wave frequency modulation, achieving a density of 94.2%; Comparative Example 4 operated at a fixed frequency, with a density of only 86.5%.

[0203] Example 4 triggered a 25s frequency modulation immediately after three consecutive energy exceedances; Comparative Example 4 did not respond, leading to energy accumulation and the formation of pores.

[0204] Example 4 has a density of 94.2%, which meets the design requirements. Comparative Example 4 has a density of 86.5%, but still has honeycomb pores. The structural reliability is improved by 8.9%.

[0205] In another embodiment, the concrete pouring method further includes the following controls during the concrete pouring process:

[0206] 1) Pre-store the compensation coefficient table, which contains the compensation coefficients corresponding to different coarse aggregate particle size ranges and height variations ΔH;

[0207] 2) When the height of the fabric assembly is adjusted:

[0208] Calculate the height change ΔH between the current height H and the initial installation height H0, where ΔH = H0 - H;

[0209] Based on the particle size range and ΔH value of the coarse aggregate, consult the compensation coefficient table to obtain the basic compensation coefficient K;

[0210] 3) Obtain the current operating frequency f of the variable frequency vibrator, and calculate the absolute value of the difference between f and f0, |△f|, where |△f| = |f - f0|;

[0211] If |△f|≤3Hz, then keep the basic compensation coefficient K unchanged;

[0212] If 3Hz < |Δf| ≤ 6Hz, then increase the basic compensation coefficient K by 0.03;

[0213] If |△f|>6Hz, then increase the basic compensation coefficient K by 0.06;

[0214] 4) Multiply the P value measured by the laser aggregate analyzer by the compensation coefficient K to obtain the calibration value P. cal ;

[0215] 5) When P is detected cal When the deviation from P0 exceeds ±5%, the height and frequency adjustment operation is triggered.

[0216] In conventional concrete pouring methods, the impact of height changes on the accuracy of coarse aggregate detection is not considered when adjusting the height of the concrete placing device, and laser measurement values ​​are used directly for control decisions without calibration.

[0217] To eliminate measurement errors caused by height adjustments, this implementation method pre-stores a compensation coefficient table containing compensation coefficients K corresponding to different coarse aggregate particle size ranges and height changes. When the height of the feeding device is adjusted, the height change ΔH (ΔH = H0 - H) between the current height H and the initial installation height H0 is calculated. Based on the particle size range of the coarse aggregate and the ΔH value, the basic compensation coefficient K is obtained from the compensation coefficient table. The absolute value |Δf| of the difference between the current operating frequency f and f0 of the variable frequency vibrator is obtained. If |Δf| ≤ 3Hz, the basic compensation coefficient K remains unchanged; if 3Hz < |Δf| ≤ 6Hz, K is increased by 0.03; if |Δf| > 6Hz, K is increased by 0.06. The original P value measured by the laser aggregate analyzer is multiplied by the compensation coefficient K to obtain the calibration value P. cal When P is detected cal When the deviation from P0 exceeds ±5%, height and frequency adjustment operations are triggered to ensure that control decisions are based on the true segregation state after calibration.

[0218] In another embodiment, in the concrete pouring method, a flow rate sensor is installed at the outlet of the hose.

[0219] When the altitude and frequency adjustment operations are triggered, the following controls are executed:

[0220] The initial concrete flow velocity is obtained by a flow velocity sensor. The initial concrete flow velocity is the average flow velocity before the adjustment operation is triggered.

[0221] The target flow velocity range is set to 0.8-1.2 times the initial concrete flow velocity;

[0222] Real-time monitoring of concrete flow velocity using flow velocity sensors;

[0223] When the concrete flow rate is greater than the upper limit of the target flow rate range, the concrete flow rate is reduced to bring the concrete flow rate back to the target flow rate range.

[0224] When the concrete flow velocity is less than the lower limit of the target flow velocity range, the concrete flow velocity is brought back to the target flow velocity range by increasing the output rate of the concrete pump.

[0225] Repeat the above flow rate monitoring and pump output rate adjustment operations until the P value detected by the laser aggregate analyzer stabilizes within the range of P0±5%.

[0226] When adjusting the output rate of the concrete pump, ensure that the total time from when the freshly mixed concrete leaves the mixing plant to when it falls into the formwork through the hose outlet is ≤60 minutes.

[0227] In conventional concrete pouring methods, after triggering height and frequency adjustment operations, relying solely on manual experience to adjust the pumping rate can easily exacerbate segregation due to sudden changes in flow rate.

[0228] This implementation method stabilizes the flow rate and suppresses secondary segregation by installing a flow rate sensor at the hose outlet. Upon triggering the height and frequency adjustment operation, closed-loop flow rate control is immediately executed: the average concrete flow rate within 30 seconds prior to triggering is acquired as the initial flow rate V0, and the target flow rate range is set to 0.8-1.2V0. The concrete flow rate V is monitored in real time. When V > 1.2V0, the concrete pump output rate is reduced to bring V back to the target range; when V < 0.8V0, the concrete pump output rate is increased to bring V back to the target range. This monitoring and adjustment is repeated until the P value stabilizes within the range of P0 ± 5%. When adjusting the pump output rate, the total time from the mixing plant to the hose outlet of the fresh concrete is strictly maintained to be ≤ 60 minutes, balancing flow rate stability and material workability. In another embodiment, in the concrete pouring method, after triggering the height and frequency adjustment operation, the following movement control is executed:

[0229] The fabric control device performs two-dimensional reciprocating movement in the horizontal plane. The starting point of the movement is the instantaneous position at the time of the trigger operation. The movement process executes the following steps in sequence:

[0230] Move a distance L along the positive X-axis of the preset horizontal rectangular coordinate system x = 0.75 times the inner diameter of the hose outlet;

[0231] Move a distance L along the positive Y-axisy = 0.5 times the inner diameter of the hose outlet;

[0232] Move a distance L along the negative X-axis x ;

[0233] Move a distance L along the negative Y-axis y ;

[0234] The moving speed is 0.1-0.3 m / s, and the continuous moving time is the same as the continuous running time of the frequency converter after increasing the frequency.

[0235] In conventional concrete pouring methods, after the height and frequency adjustment operations are triggered, the placing device remains stationary, which can easily lead to localized coarse aggregate accumulation due to fixed-point pouring.

[0236] To eliminate localized accumulation, this implementation method immediately controls the fabric distribution device to perform two-dimensional reciprocating movement in the horizontal plane after the adjustment operation is triggered. The starting point of the movement is the instantaneous position at the time of the trigger operation, and four steps are executed sequentially. First, the device moves a distance of 0.75 times the inner diameter of the hose outlet along the positive X-axis of the preset horizontal rectangular coordinate system. Second, it moves a distance of 0.5 times the inner diameter of the hose outlet along the positive Y-axis. Third, it moves the same distance along the negative X-axis. Finally, it moves the same distance along the negative Y-axis. The moving speed is strictly controlled within the range of 0.1-0.3 m / s, and the total duration of continuous movement is completely synchronized with the continuous running time of 20-40 seconds after the frequency of the variable frequency vibrator is increased, ensuring that the expansion of the fabric distribution range and the strengthening of the vibration energy are matched in time and space.

[0237] In another embodiment, the concrete pouring method includes the following air bubble control step during the concrete pouring process:

[0238] The laser aggregate analyzer takes three consecutive samples with an interval of ≥1s between each sample, measuring the mass proportions of coarse aggregate P1, P2, and P3. The fluctuation range ΔP of P1, P2, and P3 is calculated as: ΔP = max(P1, P2, P3) − min(P1, P2, P3). When ΔP ≤ 1%, bubble control is executed.

[0239] Reduce the operating frequency of the variable frequency vibrator by 3-5Hz based on f0;

[0240] The height of the concrete placing device is adjusted synchronously to control the vertical height between the outlet end of the hose and the pouring surface at 0.5-0.6m.

[0241] Maintain this state while pouring for 2-3 meters. 3 Concrete;

[0242] Once completed, restore the operating frequency and height value to the state before the bubble control operation;

[0243] After every five bubble control operations, perform bubble detection and parameter adjustment:

[0244] Level the pouring surface by 1m. 2 The area is covered with a transparent polyethylene film;

[0245] After standing for 10 minutes, count the number N of bubbles with a diameter greater than 2 mm.

[0246] If N > 15, the frequency reduction of subsequent bubble control operations will be increased by 1 Hz.

[0247] If N≤8, then the subsequent frequency reduction will be reduced by 1Hz;

[0248] If 8 < N ≤ 15, then the original frequency reduction rate remains unchanged.

[0249] In conventional concrete pouring methods, construction workers rely solely on visual observation of air bubbles on the concrete surface. When bubbles are observed to be accumulating, they manually reduce the vibration frequency or adjust the hose height. This passive response mode suffers from a lag: the intervention effect is limited after bubble aggregation, and the adjustment parameters lack quantitative basis.

[0250] This implementation addresses the aforementioned problem by performing the following operations: A laser aggregate analyzer samples the coarse aggregate mass ratios P1, P2, and P3 three times consecutively at intervals of at least 1 second. The fluctuation range ΔP of the three sample values ​​is calculated (ΔP = max(P1, P2, P3) − min(P1, P2, P3)). When ΔP ≤ 1%, bubble control is performed. This condition indicates that the aggregate coating in the slurry is abnormally uniform, making it prone to forming stable bubble pockets. The operating frequency of the variable frequency vibrator is reduced by 3-5 Hz from f0 to weaken the vibration energy and slow down the tendency for bubble merging. Simultaneously, the vertical height between the hose outlet and the pouring surface is controlled to within 0.5-0.6 m to reduce the impact force of falling concrete and suppress the generation of new bubbles. This state is maintained for pouring 2-3 m. 3 After concrete pouring, restore the original frequency and height values. Perform testing and calibration after every five bubble control operations: level the poured surface by scraping a 1m layer. 2 The area is covered with a transparent polyethylene film. After standing for 10 minutes, the number of bubbles N with a diameter greater than 2 mm is counted. If N > 15, the frequency of subsequent bubble control operations is reduced by 1 Hz. If N ≤ 8, the frequency is reduced by 1 Hz. If 8 < N ≤ 15, the original frequency is maintained. The frequency reduction parameters are dynamically optimized through the feedback of the number of bubbles to form a closed-loop control mechanism.

[0251] Example 5

[0252] The core tube pouring project of a high-rise building used coarse aggregate B with a maximum particle size of 18mm. The initial vibration frequency was set at 43Hz. An adjustable-height material distribution device and a lateral laser aggregate analyzer were installed, and a variable-frequency vibrator was installed at the end of the conveying pipe. During pouring, laser monitoring showed that at the 15th minute, the coarse aggregate mass ratio P value reached 105.8% of the design value P0, triggering height and frequency adjustment: the system automatically lowered the hose height by 0.2m to the adjusted height of 0.8m, while simultaneously increasing the vibration frequency to 48Hz and running it continuously for 30 seconds. Within 25 seconds, the P value returned to the range of P0 ± 4.2%. Subsequently, the bubble control stage began. At the 38th minute, three consecutive samplings showed a P value fluctuation range ΔP = 0.8% (P1 = 41.2%, P2 = 41.5%, P3 = 41.0%), triggering bubble control: the vibration frequency was reduced to 39Hz, the hose height was limited to 0.55m, and this state was maintained for 2.5m of pouring. 3 After concrete pouring, the original parameters are restored. Upon triggering the above adjustment operation, the system synchronously initiates a two-dimensional reciprocating movement of the concrete placing device: starting from the trigger point, it moves 0.75 times the inner diameter of the hose outlet along the positive X-axis of the horizontal rectangular coordinate system, then moves 0.5 times the inner diameter along the positive Y-axis, then moves the same distance along the negative X-axis, and finally moves the same distance along the negative Y-axis, at a speed of 0.2 m / s, lasting for 30 seconds in complete synchronization with the frequency increase period. After completing five bubble control cycles, the bubble detector shows 1 m. 2 The number of air bubbles larger than 2mm in diameter within the area was N = 6. Based on this, the subsequent frequency reduction was decreased by 1Hz (the original reduction was adjusted from 4Hz to 3Hz). An immersion vibrator was used to compact the concrete before placement, with a vibration depth of 60cm, a single-point vibration duration of 20s, and a spacing of 50cm between adjacent points. Post-setting testing showed a segregation area of ​​4.2%, a surface air bubble area of ​​2.1%, and an average pore density of 13 air bubbles / m³. 2 The flatness deviation of the poured surface is ≤3mm, and the core density is 95.8%.

[0253] Comparative Example 5

[0254] Using the same engineering conditions as in Example 5, the maximum coarse aggregate size was 18mm, falling within range B. The initial frequency was set to 43Hz, and the same monitoring and execution equipment was installed. At the 15th minute, the P value reached P0+ 5.8%, and the system normally triggered the height reduction and frequency increase operation (reducing the height by 0.2m to 0.8m, increasing the frequency to 48Hz for 30 seconds), but the material movement control function was disabled. During the bubble control stage, at the 38th minute, ΔP = 0.8%, triggering the same frequency reduction and height limit operation (frequency 39Hz, height 0.55m), but horizontal movement was not executed. Manual compaction was performed (parameters same as in Example 5), with a compaction depth of 60cm, a single-point duration of 20s, and a spacing of 50cm between adjacent points. After final setting, the segregation area accounted for 4.5%, comparable to Example 5, but local aggregate accumulation zones appeared on the casting surface (maximum accumulation height 8mm), the surface bubble area accounted for 14.3%, and the pore density significantly increased to 105 pores / m³. 2 Furthermore, the bubbles are concentrated within a 0.5m diameter range below the original trigger point, with an aggregate accumulation zone density of 87% and a bubble enrichment zone density of 83%.

[0255] Results: In Example 5, the material distribution range was expanded by two-dimensional orthogonal movement, and the flatness deviation of the casting surface was ≤3mm; in Comparative Example 5, an aggregate accumulation zone (height difference 8mm) was formed due to fixed-point casting.

[0256] The bubbles in Example 5 were uniformly dispersed, with an average density of only 13 bubbles / m³. 2 Comparative Example 5: Bubbles aggregated in the area below the trigger point, with a local density as high as 10⁵ bubbles / m³. 2 .

[0257] Example 5 optimizes the subsequent frequency reduction amplitude to 3Hz based on N = 6 to avoid excessive suppression of vibration energy; Comparative Example 5 does not eliminate the bubble aggregation phenomenon.

[0258] Example 5 showed a core density of 95.8%, while Comparative Example 5 showed a density of 87% in the aggregate accumulation zone and 83% in the bubble enrichment zone, resulting in an overall structural reliability improvement of 14.9%.

[0259] In concrete pouring, traditional methods rely on a fixed vibration frequency (usually set at 40Hz) and manual control of the hose height (usually fixed at 1.0m). Operators visually assess the segregation state of the concrete, which has significant drawbacks: human judgment is highly subjective, with different operators having vastly different opinions on the same degree of segregation, and it cannot quantify the coarse aggregate ratio in real time, only providing a rough sense of the trend; more importantly, human response has a severe lag (usually about 120 seconds). By the time an anomaly is detected and adjustments are made, approximately 1.5 cubic meters of segregated concrete have already flowed into the formwork, causing localized aggregate accumulation or slurry enrichment. Even with subsequent standard compaction, the excessive amount and uneven distribution of pre-segregated concrete make it difficult to completely eliminate its adverse effects, resulting in a high coefficient of variation in the final structural strength (often exceeding 15%) and insufficient density. The fixed parameter mode further exacerbates the problem: a single vibration frequency cannot adapt to the differences in coarse aggregate particle size (for example, when the particle size is >25mm, 40Hz vibration is insufficient, resulting in uneven aggregate settling; when the particle size is <15mm, the same frequency is prone to causing slurry to float); the fixed hose height ignores the relationship between falling kinetic energy and segregation (height >1.2m aggravates aggregate impact and accumulation; height <0.5m restricts flow and is prone to clogging).

[0260] This invention effectively solves the aforementioned problems by implementing intelligent pre-vibration control at the end of the delivery pipe—a crucial step before concrete is poured into the formwork—thus laying the foundation for effective subsequent vibration during formwork placement. Its core lies in:

[0261] First, coarse aggregates are scientifically classified into preset ranges based on their maximum particle size *d* (A: 5 ≤ d < 15 mm, B: 15 ≤ d < 25 mm, C: 25 ≤ d ≤ 40 mm). Based on this, differentiated initial operating frequencies (f0: A: 35-40 Hz, B: 40-45 Hz, C: 45-50 Hz) are set for the variable frequency vibrators at the end of the conveying pipe. This frequency matching ensures that aggregates of different sizes receive appropriate initial vibration energy during the conveying flow, optimizing the relative motion between aggregates and slurry, and initially promoting uniform distribution.

[0262] Secondly, a laser aggregate analyzer installed on the side of the hose outlet is used to quantify the mass ratio (P) of coarse aggregate in the flowing concrete in real time and with precision. When the detected P value deviates from the design value P0 by more than ±5%, the system automatically triggers closed-loop adjustment: simultaneously reducing the height of the concrete placing device by 0.1-0.3m (the adjusted height is strictly controlled within the range of 0.5-1.2m) to reduce the impact force and segregation tendency of the falling concrete, and immediately increasing the operating frequency of the variable frequency vibrator by 5-10Hz (based on f0) for 20-40s. This combination strategy of "reducing height + increasing frequency" actively intervenes and effectively disperses the initial segregation trend (such as aggregate lumps or slurry enrichment flow) through enhanced and directional radial vibration energy at the moment the concrete is about to be poured into the formwork, forcing the aggregate and slurry to re-mix uniformly.

[0263] Meanwhile, the concrete temperature (10-18℃) and total delivery time (≤60min) were strictly controlled throughout the process, maintaining good workability of the material and ensuring the effective implementation of pre-vibration. This closed-loop control of dynamic pre-vibration before placement in the formwork fundamentally intercepted most of the segregated concrete from flowing into the formwork and significantly improved the uniformity of the concrete about to be placed in the formwork.

[0264] Therefore, in the method described in this invention, the pre-vibration performed by the frequency converter at the end of the conveying pipe before placement into the mold has core effectiveness:

[0265] 1) Source Interception of Segregation: Through real-time monitoring and millisecond-level automatic adjustment (far faster than manual intervention by 120 seconds), segregation is effectively contained and corrected in its early stages or before it worsens, significantly reducing the amount of segregated concrete flowing into the formwork (e.g., only 0.3m³ in Example 2). 3 Comparative Example 2 is 1.8m 3 ).

[0266] 2) Pre-homogenized mixture: Based on the differential initial frequency setting of particle size and the trigger-type enhanced vibration, the rheological state of the concrete is actively optimized in the final stage of concrete delivery, which greatly improves the uniformity of aggregate distribution of the concrete to be poured into the formwork (for example, the uniformity of aggregate distribution in Example 1 is 56% higher than that of the traditional fixed frequency).

[0267] 3) Laying the foundation for concrete compaction before placement: Since the uniformity of the concrete before placement has been significantly improved and the segregation trend has been effectively controlled, subsequent conventional immersion vibration (depth 50-70cm, single-point 15-25s, spacing ≤60cm) can more efficiently complete the final compaction work, achieving the expected high density (Examples 1, 2, and 5 are all >94%). The final data (strength dispersion coefficient significantly reduced to around 9.2%, segregation area ratio reduced to around 5%, and density stabilized above 94%) fully demonstrates the overall superiority of this combined strategy of "precise pre-placement control + standard post-placement vibration".

[0268] The following comparison between Example 1 and Comparative Example 6 further illustrates the effect of pre-vibration of concrete before it is poured into the formwork.

[0269] Comparative Example 6

[0270] The same engineering conditions as in Example 1 were used (raft foundation of a high-rise building, with a maximum coarse aggregate size of 32mm, belonging to interval C), but the frequency converter vibrator at the end of the delivery pipe was turned off, and pre-vibration control was canceled. The laser aggregate analyzer monitored that the P-value reached P0+6.3% at the 8th minute of pouring; the system only recorded the data but did not trigger height and frequency adjustments. The hose height remained unchanged at the initial 1.0m, and the concrete was directly poured into the formwork. The poured concrete was vibrated using the same immersion vibrator parameters as in Example 1 (depth 60cm, single-point duration 20s, adjacent point spacing 50cm).

[0271] Final setting test results:

[0272] Total segregated concrete volume: 1.7m³ 3 (Example 1 is 0.3m) 3 );

[0273] The area of ​​the segregated region was 16.2% (6.5% in Example 1).

[0274] Core density: 83.5% (94.1% in Example 1);

[0275] Strength dispersion coefficient: 18.9% (9.2% in Example 1).

[0276] Effect comparison:

[0277] Without pre-vibration, even with the same in-mold vibration, the amount of segregated concrete increased by 467% and the density decreased by 11.3%, proving that pre-vibration at the end of the delivery pipe is a necessary step to ensure the uniformity of pouring.

[0278] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A concrete pouring method, characterized in that, Includes the following steps: When preparing fresh concrete, the coarse aggregate used has a particle size of 5-40mm, and the mass proportion of coarse aggregate in the design mix proportion is P0. The particle size range is determined based on the maximum particle size d of the coarse aggregate: Range A: 5mm ≤ d < 15mm; Range B: 15mm ≤ d < 25mm; Range C: 25mm ≤ d ≤ 40mm. A concrete placing device is installed above the formwork of the structure to be poured. The concrete placing device includes a rigid delivery pipe and a flexible hose at its end. Install a laser aggregate analyzer on the side of the hose outlet; A variable frequency vibrator is installed on the outer wall of the connection between the end of the rigid conveying pipe and the flexible hose. Freshly mixed concrete is pumped out. The initial operating frequency f0 of the variable frequency vibrator is set according to the particle size range of the coarse aggregate: Range A: 35-40Hz; Range B: 40-45Hz; Range C: 45-50Hz; Start the variable frequency vibrator and apply radial vibration at f0; The following controls shall be implemented during the concrete pouring process: The mass ratio P of coarse aggregate in the flowing concrete is obtained in real time using a laser aggregate analyzer. When the P value deviates from the P0 value by more than ±5%, the height and frequency adjustment operation is triggered. Adjust the height of the concrete placing device so that the vertical height between the outlet end of the hose and the current pouring surface is reduced by 0.1-0.3m, and ensure that the adjusted height is between 0.5-1.2m; Increase the operating frequency of the variable frequency vibrator by 5-10Hz based on f0 and run it continuously for 20-40 seconds; Control the pump output rate so that the total time from when the fresh concrete leaves the batching plant to when it falls into the formwork through the hose outlet is ≤60 minutes, and the temperature is maintained at 10-18℃. After the concrete is poured into the formwork, it is vibrated with an immersion vibrator. The vibration depth is 50-70cm, the vibration duration at a single point is 15-25s, and the distance between adjacent vibration points is ≤60cm.

2. The concrete pouring method as described in claim 1, characterized in that, At a concrete mixing plant, a precooling system is used to reduce the temperature of coarse aggregate to 8-15℃, and then it is mixed with cement, admixtures, additives and mixing water in a mixer to prepare fresh concrete. During the concrete pouring process, the following controls are also implemented: Use a temperature sensor inserted into the freshly mixed concrete to monitor the internal temperature of the concrete in real time; When the real-time monitored internal temperature of the concrete reaches 18℃, a cooling command is sent to the mixing plant. After receiving the cooling command, the mixing plant starts the pre-cooling system to further reduce the target temperature of the coarse aggregate to be added to the next batch of mixing to 5-10℃.

3. The concrete pouring method as described in claim 1, characterized in that, Install a laser aggregate analyzer 10-15cm to the side of the hose outlet. The central axis of the laser aggregate analyzer's detection window is at a 20-25° angle to the vertical falling direction of the concrete. A ring-shaped compressed air nozzle is integrated circumferentially into the detection window of the laser aggregate analyzer; During the concrete pouring process, the following controls are also implemented: When the difference between the highest and lowest P-values ​​detected three times consecutively by the laser aggregate analyzer exceeds 6% of the average of the three values, a cleaning operation is initiated. Activate the annular compressed air nozzle and inject compressed air at a pressure of 0.35-0.45 MPa for 4-6 seconds; After the cleaning operation is completed, obtain the P value again; If the deviation between the re-acquired P-value and the P-value of the last test before the cleaning operation exceeds ±1.5%, the cleaning operation is repeated. If, after two repeated cleaning operations, the deviation between the newly acquired P-value and the P-value detected before the last cleaning operation still exceeds ±1.5%, an alarm will be triggered and pouring will be suspended.

4. The concrete pouring method as described in claim 1, characterized in that, A triaxial vibration acceleration sensor is installed on the outer wall of the rigid delivery pipe 5-10cm above the connection between the end of the rigid delivery pipe and the flexible hose. Install a temperature sensor at the center point of the non-heat-dissipating area of ​​the variable frequency vibrator motor housing; During the concrete pouring process, the following controls are also implemented: The vibration acceleration amplitude A monitored by the triaxial vibration accelerometer and the surface temperature T monitored by the temperature sensor are acquired in real time. When any of the following conditions are met: a) A>15m / s 2 And continuously for 10 seconds; b) T > 65℃; The operating frequency of the variable frequency vibrator is automatically reduced by 4±0.5Hz from the current operating frequency; After reducing the frequency, follow these steps: If the value of A drops to ≤10m / s within 30s 2 If the T value is ≤60℃, the operating frequency will be restored to the frequency value before the frequency reduction operation. If either the A value or the T value fails to meet the standard, the reduced operating frequency will be maintained. When the cumulative frequency reduction operation time reaches 90 seconds, a shutdown alarm is triggered.

5. The concrete pouring method as described in claim 1, characterized in that, During the concrete pouring process, the following vibration energy optimization control steps should be added: Within the first 5 minutes after the start of concrete pouring, the raw signal of the concrete scattered light was collected every 30 seconds for 10 seconds using a laser aggregate analyzer. Perform spectral analysis on each 10-second signal acquisition and calculate the total signal energy value of each acquisition signal within the frequency range of 100-500Hz. Take the arithmetic mean of the total signal energy values ​​calculated independently above 10 times, and record it as the baseline energy value E0; Starting from the 5th minute after pouring begins, a new 10-second raw signal of the concrete scattered light is collected every 10 seconds using a laser aggregate analyzer, and the total signal energy value of this newly collected signal in the frequency range of 100-500Hz is calculated and recorded as the current energy value E. When the current energy value E obtained three times consecutively is greater than 1.2 times the baseline energy value E0, perform the following operations: The variable frequency vibrator is controlled with f0 as the center frequency and the output frequency is continuously adjusted according to the sine waveform. The frequency fluctuation range is ±3Hz of the center frequency. Each complete cycle from the center frequency to the peak value, to the trough value, and back to the center frequency takes 6 seconds. Maintain this sinusoidal waveform frequency adjustment mode for 25 seconds; After the operation is completed, the frequency converter will automatically return to the constant vibration mode at f0.

6. The concrete pouring method as described in claim 1, characterized in that, During the concrete pouring process, the following controls are also implemented: 1) Pre-store the compensation coefficient table, which contains the compensation coefficients corresponding to different coarse aggregate particle size ranges and height variations ΔH; 2) When the height of the fabric assembly is adjusted: Calculate the height change ΔH between the current height H and the initial installation height H0, where ΔH = H0 - H; Based on the particle size range and ΔH value of the coarse aggregate, consult the compensation coefficient table to obtain the basic compensation coefficient K; 3) Obtain the current operating frequency f of the variable frequency vibrator, and calculate the absolute value of the difference between f and f0, |△f|, where |△f| = |f -f0|; If |△f|≤3Hz, then keep the basic compensation coefficient K unchanged; If 3Hz < |Δf| ≤ 6Hz, then increase the basic compensation coefficient K by 0.03; If |△f|>6Hz, then increase the basic compensation coefficient K by 0.06; 4) Multiply the P value measured by the laser aggregate analyzer by the compensation coefficient K to obtain the calibration value P. cal ; 5) When P is detected cal When the deviation from P0 exceeds ±5%, the height and frequency adjustment operation is triggered.

7. The concrete pouring method as described in claim 1, characterized in that, Install a flow rate sensor at the hose outlet; When the altitude and frequency adjustment operations are triggered, the following controls are executed: The initial concrete flow velocity is obtained by a flow velocity sensor. The initial concrete flow velocity is the average flow velocity before the adjustment operation is triggered. The target flow velocity range is set to 0.8-1.2 times the initial concrete flow velocity; Real-time monitoring of concrete flow velocity using flow velocity sensors; When the concrete flow rate is greater than the upper limit of the target flow rate range, the concrete flow rate is reduced to bring the concrete flow rate back to the target flow rate range. When the concrete flow velocity is less than the lower limit of the target flow velocity range, the concrete flow velocity is brought back to the target flow velocity range by increasing the output rate of the concrete pump. Repeat the above flow rate monitoring and pump output rate adjustment operations until the P value detected by the laser aggregate analyzer stabilizes within the range of P0±5%. When adjusting the output rate of the concrete pump, ensure that the total time from when the freshly mixed concrete leaves the mixing plant to when it falls into the formwork through the hose outlet is ≤60 minutes.

8. The concrete pouring method as described in claim 1, characterized in that, After triggering the altitude and frequency adjustment operation, the following movement control is executed: The fabric control device performs two-dimensional reciprocating movement in the horizontal plane. The starting point of the movement is the instantaneous position at the time of the trigger operation. The movement process executes the following steps in sequence: Move a distance L along the positive X-axis of the preset horizontal rectangular coordinate system x = 0.75 times the inner diameter of the hose outlet; Move a distance L along the positive Y-axis y = 0.5 times the inner diameter of the hose outlet; Move a distance L along the negative X-axis x ; Move a distance L along the negative Y-axis y ; The moving speed is 0.1-0.3 m / s, and the continuous moving time is the same as the continuous running time of the frequency converter after increasing the frequency.

9. The concrete pouring method as described in claim 1, characterized in that, During the concrete pouring process, the following air bubble control steps should be added: The laser aggregate analyzer takes three consecutive samples with an interval of ≥1s between each sample, measuring the mass proportions of coarse aggregate P1, P2, and P3. The fluctuation range ΔP of P1, P2, and P3 is calculated as: ΔP = max(P1, P2, P3) − min(P1, P2, P3). When ΔP ≤ 1%, bubble control is executed. Reduce the operating frequency of the variable frequency vibrator by 3-5Hz based on f0; The height of the concrete placing device is adjusted synchronously to control the vertical height between the outlet end of the hose and the pouring surface at 0.5-0.6m. Maintain this state while pouring for 2-3 meters. 3 Concrete; Once completed, restore the operating frequency and height value to the state before the bubble control operation; After every five bubble control operations, perform bubble detection and parameter adjustment: Level the pouring surface by 1m. 2 The area is covered with a transparent polyethylene film; After standing for 10 minutes, count the number N of bubbles with a diameter greater than 2 mm. If N > 15, the frequency reduction of subsequent bubble control operations will be increased by 1 Hz. If N≤8, then the subsequent frequency reduction will be reduced by 1Hz; If 8 < N ≤ 15, then the original frequency reduction rate remains unchanged.