Method for detecting compressive strength of concrete based on ultrasonic rebound method

Abstract

The present application relates to the technical field of compressive strength test, and particularly relates to a concrete compressive strength detection method based on ultrasonic rebound method.The present application divides the surface of concrete structure into several concrete regions and arranges corresponding measuring points, respectively collects ultrasonic signals and surface rebound values of each measuring point, calculates concrete pressure characteristic value, determines whether the concrete of concrete region is abnormal, carries out secondary measurement, and generates several compressive strength values, uploads the abnormal compressive strength values of each abnormal concrete region to a pre-constructed compressive strength value library for comparative analysis, determines whether the compressive strength of abnormal concrete region is qualified based on the comparative analysis result, and classifies the reasons for unqualified compressive strength of abnormal concrete region based on dimensional characteristic index and sends corresponding alarm signals.The present application improves the accuracy of concrete compressive strength detection through ultrasonic rebound method detection and analysis of each concrete region.

Description

Technical Field

[0001] This invention relates to the field of compressive strength testing technology, and in particular to a method for testing the compressive strength of concrete based on the ultrasonic rebound method. Background Technology

[0002] In the field of construction engineering, concrete, as a core load-bearing material, directly determines the safety, stability, and service life of a structure through its compressive strength. From the construction quality acceptance of new buildings to the service status assessment of existing buildings, concrete compressive strength testing is a crucial step. However, traditional testing methods, on the one hand, while the core drilling method, as the benchmark method for concrete strength testing, yields accurate results, it requires drilling core samples from the structure, which has problems such as damaging the integrity of components, limited testing range, poor applicability to concealed components, and long testing cycles and high costs, making it difficult to meet the needs of large-area, rapid testing. On the other hand, the single rebound method relies solely on the surface hardness of concrete to estimate strength, which is easily affected by factors such as surface carbonization, weathering, and flatness, and has weak ability to identify internal density defects, resulting in large deviations in test results and an inability to accurately determine potential internal quality problems in concrete. Traditional methods are no longer suitable for complex engineering scenarios.

[0003] For example, Chinese Patent Publication No. CN119044336A discloses a method and system for testing the compressive strength of concrete in construction engineering. Specifically, this method involves: acquiring the ultrasonic velocity and representative rebound values ​​at various measurement locations on the concrete; calculating the acoustic interference degree at each measurement location at each acquisition time; obtaining the interference difference degree at each measurement location at each acquisition time; clustering the interference difference degrees; analyzing the difference between each cluster and other clusters regarding the mean of the interference difference degree to obtain propagation reliability; analyzing the difference in ultrasonic velocity and interference difference degree between each measurement location to be corrected and a reference measurement location; obtaining a sound velocity correction value; calculating the representative sound velocity values ​​at each location to be corrected and at each reference measurement location; and obtaining the compressive strength of the concrete at each measurement location based on the representative sound velocity values ​​and the representative rebound values. This application improves the accuracy of concrete compressive strength testing.

[0004] The following problems still exist in the existing technology:

[0005] The existing technology does not consider comprehensively evaluating the compressive strength of the concrete area through multiple measurements, nor does it consider analyzing the reasons for the failure of compressive strength based on the deviation of each measured value and the measured values ​​of concrete samples of the same type and thickness. Summary of the Invention

[0006] Therefore, the present invention provides a concrete compressive strength testing method based on ultrasonic rebound method, which overcomes the problems of existing technology that do not consider comprehensive evaluation of the compressive strength of concrete areas through multiple measurements, and do not consider analyzing the reasons for unqualified compressive strength based on the deviation of each measured value and the measured values ​​of concrete samples of the same type and thickness.

[0007] To achieve the above objectives, the present invention provides a method for testing the compressive strength of concrete based on the ultrasonic rebound method, comprising:

[0008] The surface of the concrete structure is divided into several concrete areas and corresponding measurement points are arranged. The ultrasonic signals and surface rebound values ​​of each measurement point are collected.

[0009] Based on the ultrasonic signal generation and propagation speed combined with the surface rebound value, the concrete pressure characteristic value is calculated and compared with the standard value of concrete. Based on the comparison result, it is determined whether the concrete in the concrete area corresponding to the measurement point is abnormal.

[0010] Secondary measurements are performed at the measurement points corresponding to the abnormal concrete area based on the pre-set measurement angle direction, and several compressive strength characterization values ​​are generated based on the amplitude and frequency of the ultrasonic signals obtained at different measurement angle directions.

[0011] The discrete characteristic value of sound velocity corresponding to each measurement angle direction is calculated to determine the abnormal compressive strength characterization value of the abnormal concrete area. The abnormal compressive strength characterization value of each abnormal concrete area is compared and analyzed with the preset compressive strength characterization value. Based on the comparison and analysis results, it is determined whether the compressive strength of the abnormal concrete area is qualified.

[0012] In response to the determination that the compressive strength of the abnormal concrete area is unqualified, the dimensional characteristic index of the abnormal concrete area is determined, and the reasons for the unqualified compressive strength of the abnormal concrete area are classified based on the dimensional characteristic index and a corresponding alarm signal is issued. The dimensional characteristic index is determined according to the sound velocity, amplitude and frequency of the ultrasonic signal measured in the secondary measurement.

[0013] Furthermore, the process of dividing the concrete structure surface into several concrete areas and arranging corresponding measurement points, and collecting the ultrasonic signals and surface rebound values ​​of each measurement point, includes:

[0014] The geometric center of each concrete region is selected as the measurement point for the corresponding concrete region.

[0015] The ultrasonic signals at the measurement points were acquired using a comparative measurement method.

[0016] The surface rebound value is collected in the vertical direction at the measurement point.

[0017] Furthermore, the process of calculating the concrete pressure characteristic value based on the ultrasonic signal propagation velocity and the surface rebound value, comparing it with the standard value of concrete, and determining whether the concrete in the corresponding concrete area at the measurement point is abnormal based on the comparison result includes:

[0018] Based on the propagation speed of the ultrasonic signal;

[0019] The weighted sum of the propagation velocity and the surface rebound value is determined to be the characteristic value of concrete pressure.

[0020] The standard propagation velocity and standard surface rebound value of the concrete test block with the same thickness and material as the concrete area are measured to calculate the standard value of the concrete.

[0021] Based on the comparison between the concrete pressure characteristic value and the concrete standard value, it is determined whether the concrete in the corresponding concrete area of ​​the measurement point is abnormal.

[0022] Furthermore, the determination of whether the concrete in the area corresponding to the measurement point is abnormal is based on the comparison result between the concrete pressure characteristic value and the concrete standard value.

[0023] If the concrete pressure characteristic value is less than the standard value for concrete, then the concrete area corresponding to the measurement point is determined to be abnormal.

[0024] Furthermore, the process of performing secondary measurements at the measurement points corresponding to the abnormal concrete area based on a pre-set measurement angle direction includes:

[0025] The measurement angle direction is preset, with the measurement point as the starting point of the measurement angle direction;

[0026] The oblique measurement method is used to perform secondary measurements on the abnormal concrete area based on the measurement angle direction to obtain the amplitude and frequency of the ultrasonic signal in different measurement angle directions.

[0027] Furthermore, the process of generating several compressive strength characterization values ​​based on the amplitude and frequency of ultrasonic signals acquired from different measurement angles includes:

[0028] The ratio of the amplitude data to the rated amplitude is determined as the amplitude influence factor;

[0029] The ratio of the frequency data to the rated frequency is determined as the frequency influence factor;

[0030] The weighted sum of the amplitude influence factor and the frequency influence factor is determined to be the stress resistance characterization value.

[0031] Furthermore, the process of calculating the discrete characteristic values ​​of sound velocity corresponding to each measurement angle direction to determine the abnormal compressive strength characterization value of the abnormal concrete region includes:

[0032] Obtain the secondary sound velocity value of the ultrasonic wave corresponding to each measurement angle direction, and calculate the sound velocity standard deviation of each of the secondary sound velocity values;

[0033] Calculate the mean of the standard deviation of the sound speed, and determine the mean as the discrete characteristic value of the sound speed;

[0034] If the discrete characteristic value of sound velocity is less than the preset discrete value of sound velocity, then the average of several compressive strength characterization values ​​calculated from different measurement angle directions is determined as the abnormal compressive strength characterization value.

[0035] Furthermore, the process of determining whether the compressive strength of the abnormal concrete area is qualified based on the comparative analysis results includes:

[0036] The abnormal compressive strength characterization values ​​of each abnormal concrete area are compared with the preset compressive strength characterization values;

[0037] If the abnormal compressive strength characterization value is greater than or equal to the preset compressive strength characterization value, then the compressive strength of the abnormal concrete area is determined to be qualified.

[0038] If the abnormal compressive strength characterization value is less than the preset compressive strength characterization value, then the compressive strength of the abnormal concrete area is determined to be unqualified.

[0039] Furthermore, the process of determining the dimensional characteristic indicators of the abnormal concrete area includes:

[0040] The differences between the sound velocity, amplitude, and frequency of the ultrasonic signals measured in the second measurement and the sound velocity, amplitude, and frequency of the samples corresponding to the same concrete type were determined.

[0041] The mean of several of the aforementioned differences is taken as the dimension feature index.

[0042] Furthermore, based on the aforementioned dimensional feature indicators, the reasons for the substandard compressive strength of the abnormal concrete area are classified and corresponding alarm signals are issued, wherein,

[0043] If the dimensional feature index is less than the preset feature index, the reason for the unqualified compressive strength of the abnormal concrete area is determined to be due to the raw material ratio, and a ratio alarm signal is issued.

[0044] If the dimensional characteristic index is greater than or equal to the preset characteristic index, the reason for the unqualified compressive strength of the abnormal concrete area is determined to be due to construction operation, and a construction alarm signal is issued.

[0045] Compared with existing technologies, the beneficial effects of this invention are as follows: By dividing the surface of a concrete structure into several concrete regions and arranging corresponding measurement points, ultrasonic signals and surface rebound values ​​are collected at each measurement point. Based on the propagation speed of the ultrasonic signal and the surface rebound value, the concrete pressure characteristic value is calculated and compared with the standard value of concrete. Based on the comparison results, it is preliminarily determined whether the concrete in the corresponding concrete region of the measurement point is abnormal. By simultaneously collecting ultrasonic signals and generating sound velocity, which reflects the internal density and elastic modulus, and rebound value, which reflects the surface hardness, the pressure characteristic value is calculated by integrating parameters from two dimensions: internal structural state and surface performance. This eliminates the one-sided interference of a single parameter on the test results from the source, making the strength assessment more consistent with the true quality state of the concrete. This partitioned + multi-point sampling mode significantly reduces sampling random errors, allowing the test results to truly reflect the strength distribution of each region of the structure. It can quickly screen out key areas of concern in the early stage of testing, improving the accuracy of concrete compressive strength testing.

[0046] Furthermore, this invention performs secondary measurements at measurement points corresponding to the abnormal concrete area based on pre-set measurement angles. It generates several compressive strength characterization values ​​based on the amplitude and frequency of ultrasonic signals acquired at different measurement angles, calculates the discrete characteristic value of sound velocity corresponding to each measurement angle to determine the abnormal compressive strength characterization value of the abnormal concrete area, and performs preliminary detection. For example, in zoned point-to-point measurements, a single fixed angle is typically used. If the measurement method penetrates vertically, only ultrasonic information from a single propagation path can be obtained, which is prone to information omission due to directional differences in the internal structure. By covering the interior of the abnormal area with multi-directional ultrasonic propagation paths: ultrasonic waves at different angles penetrate structures of different depths and orientations; tilted angles can capture tilted cracks missed by vertical angles; and when cracks intersect with the ultrasonic path, significant amplitude attenuation occurs. The secondary measurement generates compressive strength characterization values ​​based on amplitude and frequency. By supplementing information in two key dimensions, the strength correlation model is improved. By quantifying the fluctuation degree of sound velocity at different angles, the overall anomaly and local interference are accurately distinguished, further improving the accuracy of concrete compressive strength detection.

[0047] Furthermore, this invention uploads the abnormal compressive strength characterization values ​​of each abnormal concrete area to a pre-constructed compressive strength characterization value library for comparative analysis. Based on the comparative analysis results, it determines whether the compressive strength of the abnormal concrete area is qualified. During project construction, a compressive strength characterization value library for concrete specific to the project is constructed, and a standardized judgment and verification system is established. The comparative analysis of abnormal compressive strength characterization values ​​with the preset characterization value library, through massive data interval definition, standard body system benchmark, reverse verification to eliminate errors, empirical case anchoring reality, and dynamic iterative optimization logic, solves the core pain points of indirect detection from four dimensions: certainty of indirect calculation, uniformity of judgment benchmark, verifiability of data authenticity, and empirical support of results. It upgrades the strength judgment of abnormal areas from indirect calculation based on a single parameter to accurate verification based on massive empirical data, thereby significantly improving the accuracy of concrete compressive strength detection, providing a more reliable decision-making basis for structural safety assessment, and further improving the accuracy of concrete compressive strength detection.

[0048] Furthermore, this invention, under the condition that the compressive strength of abnormal concrete areas is unqualified, determines the degree of deviation between the measured values ​​of the abnormal concrete areas and the measured values ​​of concrete samples of the same type and thickness. It then classifies the causes of the unqualified compressive strength in the abnormal concrete areas and issues corresponding alarm signals. Through precise matching of deviation characteristics with causes, it avoids misinterpretation of test results due to general attribution. The ultimate value of test accuracy lies in guiding subsequent rectification. If only a general alarm for unqualified concrete is issued, rectification measures may over-process or omit key issues, conversely proving that the initial test did not accurately locate the problem, affecting the acceptance of accuracy. Targeted alarms based on deviation classification can directly guide precise rectification, further improving the accuracy of concrete compressive strength testing. Attached Figure Description

[0049] Figure 1 This is a flowchart illustrating the steps of the concrete compressive strength testing method based on the ultrasonic rebound method of the present invention.

[0050] Figure 2 This invention provides a step-by-step diagram for determining whether the concrete in the concrete area corresponding to the measurement point is abnormal.

[0051] Figure 3 This is a flowchart illustrating the logic of the present invention for determining whether the compressive strength of abnormal concrete areas is qualified.

[0052] Figure 4 This is a flowchart illustrating the logic of classifying the reasons for the substandard compressive strength of the abnormal concrete area according to the present invention. Detailed Implementation

[0053] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0054] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0055] It should be noted that in the description of this invention, the terms "upper," "lower," "inner," "outer," etc., which indicate the direction or positional relationship, are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0056] Please see Figure 1 The diagram shows the steps of the concrete compressive strength testing method based on the ultrasonic rebound method of the present invention. The concrete compressive strength testing method based on the ultrasonic rebound method of the present invention includes:

[0057] Step S1: Divide the concrete structure surface into several concrete areas and arrange corresponding measurement points, and collect the ultrasonic signals and surface rebound values ​​of each measurement point respectively.

[0058] Step S2: Calculate the concrete pressure characteristic value based on the ultrasonic signal propagation speed and surface rebound value, and compare it with the standard value of concrete. Based on the comparison result, determine whether the concrete in the corresponding concrete area of ​​the measurement point is abnormal.

[0059] Step S3: Perform secondary measurements at the measurement points corresponding to the abnormal concrete area based on the pre-set measurement angle direction, and generate several compressive strength characterization values ​​based on the amplitude and frequency of the ultrasonic signals obtained at different measurement angle directions.

[0060] Step S4: Calculate the discrete characteristic value of sound velocity corresponding to each measurement angle direction to determine the abnormal compressive strength characterization value of the abnormal concrete area. Compare and analyze the abnormal compressive strength characterization value of each abnormal concrete area with the preset compressive strength characterization value. Based on the comparison and analysis results, determine whether the compressive strength of the abnormal concrete area is qualified.

[0061] Step S5: In response to the judgment result that the compressive strength of the abnormal concrete area is unqualified, determine the dimensional characteristic index of the abnormal concrete area, classify the reasons for the unqualified compressive strength of the abnormal concrete area based on the dimensional characteristic index, and issue corresponding alarm signals. The dimensional characteristic index is determined according to the sound velocity, amplitude and frequency of the ultrasonic signal measured in the second measurement.

[0062] It is understandable that the ultrasonic measuring lines and rebound measuring points should be matched one-to-one at the measurement points.

[0063] Specifically, in step S1, the process of dividing the concrete structure surface into several concrete areas and arranging corresponding measurement points, and collecting the ultrasonic signals and surface rebound values ​​of each measurement point, includes:

[0064] Select the geometric center of each concrete area as the measurement point for that concrete area;

[0065] The ultrasonic signals at the measurement points were acquired using a comparative measurement method;

[0066] Surface rebound values ​​are collected in the vertical direction at the measurement points.

[0067] It is understandable that for those skilled in the art, collecting ultrasonic signals and surface rebound values ​​at each measurement point is existing technology, and will not be elaborated upon here.

[0068] Please see Figure 2 The diagram illustrates the steps of this invention for determining whether the concrete in the area corresponding to the measurement point is abnormal. In step S2, the concrete pressure characteristic value is calculated based on the ultrasonic signal propagation velocity and surface rebound value, and compared with the standard value of concrete. The process of determining whether the concrete in the area corresponding to the measurement point is abnormal based on the comparison result includes:

[0069] Step S201: Generate propagation speed based on ultrasonic signal;

[0070] Step S202: Determine the weighted sum of the propagation velocity and the surface rebound value as the characteristic value of concrete pressure;

[0071] Step S203: Measure the standard propagation velocity and standard surface rebound value of a concrete test block with the same thickness and material as the concrete area, and calculate the standard value of the concrete.

[0072] Step S204: Based on the comparison results between the concrete pressure characteristic value and the concrete standard value, determine whether the concrete in the corresponding concrete area of ​​the measurement point is abnormal.

[0073] Specifically, the sum of the weighting coefficients for propagation speed and surface rebound value is 1. Since propagation speed and surface rebound value characterize the compressive strength of concrete from acoustic and mechanical perspectives, respectively, the weighting coefficient for propagation speed is generally taken as 0.5, and the weighting coefficient for surface rebound value is also taken as 0.5.

[0074] Specifically, the concrete pressure characteristic value = 0.5x propagation velocity / 100 + 0.5x surface rebound value, where the propagation velocity is in m / s, and only the numerical value is taken when calculating the above formula.

[0075] In one specific embodiment, a C30 concrete component with a thickness of 200 mm was selected for testing. The measured sound velocity at the measurement point was 3700 m / s, the surface rebound value was 35, and the concrete pressure characteristic value was 36.

[0076] A standard concrete test block with the same thickness (200mm) and material (C30) as the component was made. The standard propagation velocity at the measurement point of the test block was measured to be 4000m / s, and the standard surface rebound value was 38. Therefore, the standard value of the concrete was 39.

[0077] Specifically, in step S2, based on the comparison between the concrete pressure characteristic value and the concrete standard value, it is determined whether the concrete in the corresponding concrete area at the measurement point is abnormal.

[0078] If the characteristic value of concrete pressure is less than the standard value of concrete, then the concrete in the area corresponding to the measurement point is determined to be abnormal.

[0079] If the concrete pressure characteristic value is greater than or equal to the concrete standard value, then the concrete in the area corresponding to the measurement point is considered normal.

[0080] In one specific embodiment, the measured standard value of concrete is 39. If the concrete pressure characteristic value of 36 is less than the standard value of concrete, then the concrete area corresponding to the measurement point is determined to be abnormal.

[0081] If the concrete pressure characteristic value is 40, which is greater than the standard value for concrete, then the concrete in the area corresponding to the measurement point is considered normal.

[0082] Specifically, in step S3, the process of performing secondary measurements at the measurement points corresponding to the abnormal concrete area based on the pre-set measurement angle direction includes:

[0083] The measurement angle direction is preset, with the measurement point as the starting point of the measurement angle direction;

[0084] The oblique measurement method is used to perform secondary measurements on the abnormal concrete area based on the measurement angle direction to obtain the amplitude and frequency of the ultrasonic signal in different measurement angle directions.

[0085] Specifically, this invention divides the surface of a concrete structure into several concrete regions and arranges corresponding measurement points. Ultrasonic signals and surface rebound values ​​are collected at each measurement point. Based on the propagation speed of the ultrasonic signal and the surface rebound value, the concrete pressure characteristic value is calculated and compared with the standard value of concrete. Based on the comparison results, it is preliminarily determined whether the concrete in the corresponding region of the measurement point is abnormal. By simultaneously collecting ultrasonic signals and generating sound velocity, reflecting internal density and elastic modulus, and rebound value, reflecting surface hardness, the pressure characteristic value is calculated by integrating parameters from both the internal structural state and surface performance dimensions. This eliminates the one-sided interference of a single parameter on the test results from the source, making the strength assessment more closely reflect the true quality state of the concrete. This partitioned + multi-point sampling mode significantly reduces sampling random errors, allowing the test results to truly reflect the strength distribution of each region of the structure. It can quickly screen out key areas of concern in the early stages of testing, improving the accuracy of concrete compressive strength testing.

[0086] Specifically, in step S3, the process of generating several compressive strength characterization values ​​based on the amplitude and frequency of the ultrasonic signals obtained from different measurement angles includes:

[0087] The ratio of the amplitude data to the rated amplitude is determined as the amplitude influence factor;

[0088] The ratio of the frequency data to the rated frequency is determined as the frequency influence factor;

[0089] The weighted sum of the amplitude influence factor and the frequency influence factor is determined to be the stress resistance characterization value.

[0090] In one specific embodiment, the amplitude data of the concrete area was measured to be 38dB, the frequency data was 48kHz, the rated amplitude was measured to be 40dB, the rated frequency was 50kHz, the amplitude influence factor was 0.95, the frequency influence factor was 0.96, and therefore the compressive strength characterization value was 0.955.

[0091] Specifically, in practice, the rated amplitude is the average of several measured amplitudes of concrete test blocks of the same thickness and material in the measured concrete area, and the rated frequency is the average of several measured frequencies of concrete test blocks of the same thickness and material in the measured concrete area.

[0092] Specifically, the sum of the weighting coefficients of the amplitude influence factor and the frequency influence factor is 1, the weighting coefficient of the amplitude influence factor is 0.5, and the weighting coefficient of the frequency influence factor is 0.5.

[0093] Specifically, in step S4, the process of calculating the discrete characteristic values ​​of sound velocity corresponding to each measurement angle direction to determine the abnormal compressive strength characterization value of the abnormal concrete region includes:

[0094] Obtain the secondary sound velocity values ​​of the ultrasonic waves corresponding to each measurement angle direction, and calculate the standard deviation of the sound velocity for each secondary sound velocity value.

[0095] Calculate the mean of the standard deviation of the speed of sound, and determine the mean as the discrete characteristic value of the speed of sound;

[0096] If the discrete characteristic value of sound velocity is less than the preset discrete value of sound velocity, then the average of several compressive strength characterization values ​​calculated from different measurement angles is determined as the abnormal compressive strength characterization value.

[0097] In one specific embodiment, a preset sound velocity discrete value is set to 0.2. If the sound velocity discrete characteristic value is 0.18, which is less than the preset sound velocity discrete value, then the average of several compressive strength characterization values ​​calculated from different measurement angle directions is determined to be the abnormal compressive strength characterization value.

[0098] It is understandable that the sound velocity of ultrasound in concrete is generally between 3000m / s and 4500m / s, so the preset sound velocity dispersion value is selected between 50 and 200 based on the measurement accuracy.

[0099] Specifically, this invention performs secondary measurements at measurement points corresponding to abnormal concrete areas based on pre-set measurement angles. It generates several compressive strength characterization values ​​based on the amplitude and frequency of ultrasonic signals acquired at different measurement angles. The discrete characteristic value of sound velocity corresponding to each measurement angle is calculated to determine the abnormal compressive strength characterization value of the abnormal concrete area. Preliminary detection, such as comparative measurements with zoned points, typically uses a single fixed angle. Vertical penetration in comparative measurements only acquires ultrasonic information from a single propagation path, easily leading to information omissions due to directional differences in internal structures. By covering the interior of the abnormal area with multi-directional ultrasonic propagation paths: ultrasonic waves at different angles penetrate structures of different depths and orientations; tilted angles can capture tilted cracks missed by vertical angles; and significant amplitude attenuation occurs when cracks intersect with the ultrasonic path. The secondary measurement generates compressive strength characterization values ​​based on amplitude and frequency. By supplementing information in two key dimensions, the strength correlation model is improved. By quantifying the fluctuation degree of sound velocity at different angles, the overall anomaly and local interference are accurately distinguished, further improving the accuracy of concrete compressive strength detection.

[0100] Please see Figure 3 As shown, this is a flowchart illustrating the logic of determining whether the compressive strength of the abnormal concrete area is qualified according to the present invention. In step S4, the process of determining whether the compressive strength of the abnormal concrete area is qualified based on the comparative analysis results includes:

[0101] The abnormal compressive strength characterization values ​​of each abnormal concrete area are compared with the preset compressive strength characterization values;

[0102] If the abnormal compressive strength characterization value is greater than or equal to the preset compressive strength characterization value, then the compressive strength of the abnormal concrete area is determined to be qualified.

[0103] If the abnormal compressive strength characterization value is less than the preset compressive strength characterization value, the compressive strength of the abnormal concrete area is deemed unqualified.

[0104] In one specific embodiment, a preset compressive strength characterization value is set to 0.9. If the abnormal compressive strength characterization value of 0.955 is greater than the preset compressive strength characterization value, the compressive strength of the abnormal concrete area is determined to be qualified.

[0105] If the abnormal compressive strength characterization value is 0.87, which is less than the preset compressive strength characterization value, then the compressive strength of the abnormal concrete area is deemed unqualified.

[0106] It is understandable that the closer the compressive strength characterization value is to 1, the closer the amplitude and frequency are to the rated value. The lower the value, the more severe the amplitude attenuation and the greater the frequency deviation. Therefore, the preset compressive strength characterization value is generally taken as 0.9 to 0.95.

[0107] Specifically, this invention uploads the abnormal compressive strength characterization values ​​of various abnormal concrete areas to a pre-built compressive strength characterization value library for comparative analysis. Based on the comparative analysis results, it determines whether the compressive strength of the abnormal concrete areas is qualified. During project construction, a compressive strength characterization value library for concrete specific to the project is constructed, and a standardized judgment and verification system is established. The comparative analysis of abnormal compressive strength characterization values ​​with the preset characterization value library, through massive data interval definition, standard body system benchmark, reverse verification to eliminate errors, empirical case anchoring to reality, and dynamic iterative optimization logic, solves the core pain points of indirect detection from four dimensions: certainty of indirect calculation, uniformity of judgment benchmark, verifiability of data authenticity, and empirical support of results. It upgrades the strength judgment of abnormal areas from indirect calculation based on a single parameter to accurate verification based on massive empirical data, thereby significantly improving the accuracy of concrete compressive strength detection, providing a more reliable decision-making basis for structural safety assessment, and further improving the accuracy of concrete compressive strength detection.

[0108] Specifically, in step S5, the process of determining the dimensional characteristic indicators of the abnormal concrete area includes:

[0109] The differences between the sound velocity, amplitude, and frequency of the ultrasonic signals measured in the second measurement and the sound velocity, amplitude, and frequency of the samples corresponding to the same concrete type were determined.

[0110] The mean of several degrees of difference is taken as the dimensional feature index.

[0111] Specifically, the degree of difference is the ratio of the absolute value of the difference between two corresponding values ​​to the mean of the two values; the dimensional feature index is the mean of several degrees of difference.

[0112] Please see Figure 4As shown, this is a flowchart illustrating the logic of classifying the causes of unqualified compressive strength in abnormal concrete areas according to the present invention. In step S5, the causes of unqualified compressive strength in abnormal concrete areas are classified based on dimensional feature indicators, and corresponding alarm signals are issued.

[0113] If the dimensional characteristic index is less than the preset characteristic index, the reason for the unqualified compressive strength of the abnormal concrete area is determined to be the raw material ratio and a ratio alarm signal is issued.

[0114] If the dimensional characteristic index is greater than or equal to the preset characteristic index, the reason for the unqualified compressive strength of the abnormal concrete area is determined to be due to construction operation, and a construction alarm signal is issued.

[0115] In a specific embodiment, the preset feature index is set to 0.1. If the dimension feature index is 0.096, which is less than the preset feature index, the reason for the unqualified compressive strength of the abnormal concrete area is determined to be the raw material ratio and a ratio alarm signal is issued.

[0116] If the dimensional feature index is 0.309, which is greater than the preset feature index, the reason for the unqualified compressive strength of the abnormal concrete area is determined to be due to construction operation, and a construction alarm signal is issued.

[0117] It is understandable that the dimensional feature index reflects the overall deviation between the secondary measurement parameters and the sample parameters. Preferably, the preset value range of the feature index is 0.05 to 0.1.

[0118] Specifically, this invention determines the degree of deviation between the measured values ​​of abnormal concrete areas and those of concrete samples of the same type and thickness when the compressive strength of the abnormal concrete area is substandard. It then classifies the causes of the substandard compressive strength in the abnormal concrete area and issues corresponding alarm signals. By accurately matching deviation characteristics with causes, it avoids misinterpretations of test results due to general attribution. The ultimate value of test accuracy lies in guiding subsequent rectification. If only a general alarm for non-compliance is issued, rectification measures may over-process or omit key issues, conversely proving that the initial test did not accurately locate the problem, affecting the acceptance of accuracy. Targeted alarms based on deviation classification can directly guide precise rectification, further improving the accuracy of concrete compressive strength testing.

[0119] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0120] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting the compressive strength of concrete based on the ultrasonic rebound method, characterized by, The method comprises the following steps: dividing the surface of the concrete structure into a plurality of concrete regions and arranging corresponding measuring points, respectively collecting the ultrasonic signals and surface rebound values of each measuring point; generating the propagation speed based on the ultrasonic signals, combining the surface rebound values to calculate the concrete pressure characteristic value and comparing it with the concrete standard value, and determining whether the concrete of the concrete region corresponding to the measuring point is abnormal based on the comparison result; based on the pre-set measuring angle direction, performing secondary measurement on the measuring point corresponding to the abnormal concrete region, and generating a plurality of compression resistance characteristic values according to the amplitude and frequency of the ultrasonic signals obtained in different measuring angle directions; calculating the sound velocity dispersion characteristic value corresponding to each measuring angle direction to determine the abnormal compression resistance characteristic value of the abnormal concrete region, comparing the abnormal compression resistance characteristic value of each abnormal concrete region with the pre-set compression resistance characteristic value, and determining whether the compression strength of the abnormal concrete region is qualified based on the comparison result; in response to the determination result that the compression strength of the abnormal concrete region is unqualified, determining the dimensional characteristic index of the abnormal concrete region, classifying the reason for the unqualified compression strength of the abnormal concrete region based on the dimensional characteristic index, and issuing a corresponding alarm signal, wherein the dimensional characteristic index is determined according to the sound velocity, amplitude and frequency of the ultrasonic signals obtained by the secondary measurement.

2. The ultrasonic rebound method-based concrete compressive strength detection method according to claim 1, characterized by, The process of dividing the surface of the concrete structure into a plurality of concrete regions and arranging corresponding measuring points, respectively collecting the ultrasonic signals and surface rebound values of each measuring point, comprises: selecting the geometric center of each concrete region as the measuring point of the corresponding concrete region; collecting the ultrasonic signals of the measuring point by using the direct measurement method; collecting the surface rebound value in the vertical direction of the measuring point.

3. The ultrasonic rebound method-based concrete compressive strength detection method according to claim 2, characterized by, The process of generating the propagation speed based on the ultrasonic signals, combining the surface rebound values to calculate the concrete pressure characteristic value and comparing it with the concrete standard value, and determining whether the concrete of the concrete region corresponding to the measuring point is abnormal based on the comparison result, comprises: generating the propagation speed based on the ultrasonic signals; determining the weighted sum value of the propagation speed and the surface rebound value as the concrete pressure characteristic value; measuring the standard propagation speed and standard surface rebound value of the concrete test block with the same thickness and same material as the concrete region to calculate and generate the concrete standard value; determining whether the concrete of the concrete region corresponding to the measuring point is abnormal based on the comparison result of the concrete pressure characteristic value and the concrete standard value.

4. The ultrasonic rebound method-based concrete compressive strength detection method according to claim 3, characterized by, The process of determining whether the concrete of the concrete region corresponding to the measuring point is abnormal based on the comparison result of the concrete pressure characteristic value and the concrete standard value, wherein, if the concrete pressure characteristic value is less than the concrete standard value, it is determined that the concrete of the concrete region corresponding to the measuring point is abnormal.

5. The ultrasonic rebound method-based concrete compressive strength detection method according to claim 1, characterized by, The process of performing secondary measurement on the measuring point corresponding to the abnormal concrete region based on the pre-set measuring angle direction, comprises: pre-setting the measuring angle direction, taking the measuring point as the starting point of the measuring angle direction; using the oblique measurement method to perform secondary measurement on the abnormal concrete region based on the measuring angle direction to obtain the amplitude and frequency of the ultrasonic signals in different measuring angle directions.

6. The ultrasonic rebound method-based concrete compressive strength detection method according to claim 5, characterized by, The process of generating several compression resistance characteristic values according to the amplitude and frequency of the ultrasonic signals obtained at different measurement angle directions comprises: determining the ratio of the amplitude data to the rated amplitude as an amplitude influence factor; determining the ratio of the frequency data to the rated frequency as a frequency influence factor; determining the weighted sum of the amplitude influence factor and the frequency influence factor as a compression resistance characteristic value.

7. The ultrasonic rebound method-based concrete compressive strength detection method according to claim 6, characterized by, The process of calculating the acoustic velocity discrete characteristic value corresponding to each measurement angle direction to determine the abnormal compression resistance characteristic value of the abnormal concrete region comprises: obtaining the secondary acoustic velocity value of the ultrasonic wave corresponding to each measurement angle direction, and calculating the acoustic velocity standard deviation of each secondary acoustic velocity value; calculating the mean value of the acoustic velocity standard deviation, and determining the mean value as the acoustic velocity discrete characteristic value; if the acoustic velocity discrete characteristic value is less than a preset acoustic velocity discrete value, determining the mean value of the several compression resistance characteristic values generated by the calculation of different measurement angle directions as the abnormal compression resistance characteristic value.

8. The ultrasonic rebound method-based concrete compressive strength detection method according to claim 7, characterized by, The process of determining whether the compression strength of the abnormal concrete region is qualified based on the comparison analysis result comprises: comparing the abnormal compression resistance characteristic value of each abnormal concrete region with a preset compression resistance characteristic value; if the abnormal compression resistance characteristic value is greater than or equal to the preset compression resistance characteristic value, determining that the compression strength of the abnormal concrete region is qualified; if the abnormal compression resistance characteristic value is less than the preset compression resistance characteristic value, determining that the compression strength of the abnormal concrete region is unqualified.

9. The ultrasonic rebound method-based concrete compressive strength detection method according to claim 8, characterized in that, The process of determining the dimension characteristic index of the abnormal concrete region comprises: respectively determining the several degrees of difference between the acoustic velocity, amplitude and frequency of the twice measured ultrasonic signals and the sample acoustic velocity, sample amplitude and sample frequency corresponding to the same concrete model; taking the mean value of the several degrees of difference as the dimension characteristic index.

10. The ultrasonic rebound method-based concrete compressive strength detection method according to claim 9, characterized by, Based on the dimension characteristic index, the causes of the unqualified compression strength of the abnormal concrete region are classified and the corresponding alarm signal is sent, wherein, if the dimension characteristic index is less than a preset characteristic index, it is determined that the cause of the unqualified compression strength of the abnormal concrete region is the raw material proportioning cause and the proportioning alarm signal is sent; if the dimension characteristic index is greater than or equal to the preset characteristic index, it is determined that the cause of the unqualified compression strength of the abnormal concrete region is the construction operation cause and the construction alarm signal is sent.

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