Ultrasonic Testing Method for Sulfate Corrosion of Concrete Excluding the Influence of Coarse Aggregates

Abstract

The present invention discloses a method for ultrasonic testing of sulfate corrosion of concrete by eliminating the influence of coarse aggregates. The initial value of the wave velocity of concrete is obtained through ultrasonic waves, the CT image of the concrete in the plane where the ultrasonic measuring line is located is obtained, the proportion of coarse aggregates on the ultrasonic measuring line is obtained based on the CT image, and the wave velocity correction value is obtained based on the proportion of coarse aggregates and the wave velocity of the same ultrasonic waves in the coarse aggregates. The method for ultrasonic testing of sulfate corrosion of concrete by eliminating the influence of coarse aggregates of the present invention has the advantages of simple steps, convenient implementation, accurate calibration, and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of building testing, and particularly to an ultrasonic testing method for concrete sulfate corrosion that eliminates the influence of coarse aggregates. Background Art

[0002] The ultrasonic non-destructive testing technology is a non-destructive technology based on the propagation of elastic waves. The propagation speed of the waves depends on the density and stiffness of the material to be measured. Therefore, the ultrasonic testing technology can be used to test the performance of materials such as concrete. Ultrasonic testing reflects the internal situation of the object to be measured by measuring the average sound velocity of the straight-line distance between two measuring points. The smaller the sound velocity inside the material to be measured, the greater the degree of corrosion. At present, ultrasonic velocity testing is often used in relatively homogeneous structural materials such as mortar. However, for heterogeneous materials such as concrete, which is composed of a cement matrix, aggregates, and pores, when the concrete structure is subjected to sulfate erosion, only the cement matrix and the internal pores will change, while the coarse aggregates are hardly eroded. Also, because the distribution of coarse aggregates in the concrete structure is extremely uneven, it is inaccurate to directly use ultrasonic testing velocity to judge the corrosion situation of the concrete structure in current research, resulting in the need for a large amount of various data for calibration when ultrasonic is used for concrete testing. And if computer tomography (CT) technology is used to calculate the concrete performance, there will be problems such as extremely large computational amount, many detection times, and high cost. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an ultrasonic testing method for concrete sulfate corrosion that eliminates the influence of coarse aggregates, has simple steps, is easy to implement, is accurately calibrated, and has low cost.

[0004] To solve the above technical problem, the technical solution proposed by the present invention is:

[0005] An ultrasonic testing method for concrete sulfate corrosion that eliminates the influence of coarse aggregates, obtains an initial wave velocity test value of the concrete through ultrasonic waves, obtains a CT image of the concrete in the plane where the ultrasonic measuring line is located, obtains the proportion of coarse aggregates on the ultrasonic measuring line based on the CT image, and obtains a wave velocity correction value based on the proportion of coarse aggregates and the wave velocity of the same ultrasonic waves in the coarse aggregates.

[0006] As a further improvement of the above technical solution:

[0007] The wave velocity correction value V of the concrete 修正值 The obtaining steps are:

[0008] S1: Obtain the acoustic time passed by the measuring line in at least one direction of the concrete to be tested through ultrasonic waves, and combine with the measuring line length L 测线 To obtain the initial wave velocity test value V of the concrete 测试初值 ;

[0009] S2: Obtain the CT image of the concrete in the plane where the ultrasonic measuring line is located, process the CT image, and extract the coarse aggregate area based on the edge features of the coarse aggregate;

[0010] S3: Mark the position of the measuring line in the CT image to obtain the length L of the coarse aggregate on the measuring line 粗骨料 , and according to obtain the length ratio ω of the coarse aggregate on the ultrasonic measuring line;

[0011] S4: Obtain the wave velocity correction value V based on the ratio and the wave velocity of the same ultrasonic wave in the coarse aggregate 修正值 .

[0012] The testing method further includes step S0: Core or cut samples from the concrete to be tested on site to obtain cylindrical specimens;

[0013] And then obtain the initial wave velocity test values V 测试初值x , V 测试初值y , V 测试初值z by ultrasonic waves in three mutually perpendicular directions X, Y, and Z of the cylinder; and finally obtain the wave velocity correction values V 修正值x , V 修正值y , V 修正值z .

[0014] Among the measuring lines in the three directions X, Y, and Z, one measuring line coincides with the axis of the cylindrical specimen, and the other two measuring lines are on the same section perpendicular to the axis and both pass through the center of the section.

[0015] During testing, the wave velocity correction value V 修正值 is obtained through the following processing:

[0016]

[0017] where ω is the length ratio of the coarse aggregate on the ultrasonic measuring line, V 测试初值 is the initial wave velocity test value of the ultrasonic wave to obtain the concrete, and V 粗骨料 is the wave velocity value of the same ultrasonic wave in the coarse aggregate.

[0018] The obtaining steps of the said V 粗骨料 are as follows:

[0019] S1: Prepare concrete standard specimens with the same mix ratio as that during the construction of the concrete to be tested, and cure the specimens;

[0020] S2: Obtain the acoustic time T passed by the measuring line through ultrasonic waves in at least one direction of the concrete standard specimen;

[0021] S3: Obtain the CT image of the concrete standard specimen in the plane where the ultrasonic measuring line is located, process the CT image, and extract the coarse aggregate area based on the edge features of the coarse aggregate;

[0022] S4: Mark the position of the measuring line in the CT image to obtain the length L of the coarse aggregate on the measuring line 粗骨料 and the length L of the non - coarse aggregate 非粗骨料 ;

[0023] S5: Obtain V through the following processing 粗骨料 :

[0024]

[0025] where V 非粗骨料 is the wave velocity value of the ultrasonic wave in the non - coarse aggregate part of the concrete standard specimen.

[0026] Obtain the acoustic time T x and T y that the measuring line passes through in two mutually perpendicular directions X and Y in the same plane of the concrete standard specimen by ultrasonic waves, and obtain V 粗骨料 and V 非粗骨料 through the following processing:

[0027]

[0028] Compared with the prior art, the advantages of the present invention are as follows:

[0029] The ultrasonic test method for concrete sulfate corrosion that eliminates the influence of coarse aggregate in the present invention first obtains the initial value of the wave velocity test of concrete by ultrasonic waves. Due to the influence of coarse aggregate, this initial test value cannot accurately reflect the erosion situation of sulfate and needs to be corrected. Therefore, obtain the CT image of the concrete in the plane where the ultrasonic measuring line is located, obtain the proportion of the coarse aggregate on the ultrasonic measuring line based on the CT image, separate the coarse aggregate part and the non - coarse aggregate part of the concrete, and then obtain the wave velocity correction value based on the proportion of the coarse aggregate and the wave velocity of the same ultrasonic wave in the coarse aggregate, so as to eliminate the influence of the coarse aggregate on the wave velocity and obtain an accurate measurement value, solving the problem of ultrasonic wave velocity test of different components in the concrete specimen and the problem of the influence of different components on the change of wave velocity after sulfate corrosion of the concrete specimen. And compared with using a single CT scan calculation, this test method only scans at the measuring line, greatly reducing the number of scans required, saving a large amount of costs, and combining ultrasonic velocity measurement, saving a large amount of calculation processes, improving the test efficiency, and ensuring the test accuracy at the same time. Description of the Drawings

[0030] Figure 1 is a schematic diagram of obtaining the CT image;

[0031] Figure 2 It is a schematic diagram for marking the position of the measurement line in the CT image;

[0032] Figure 3 It is a schematic structural diagram of the concrete cylinder specimen to be tested. Specific implementation mode

[0033] For the convenience of understanding the present invention, the following will describe the present invention more comprehensively and meticulously in conjunction with the accompanying drawings of the specification and preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0034] Embodiment:

[0035] As Figure 1 and Figure 2 shown, in the ultrasonic test method for sulfate corrosion of concrete with the influence of coarse aggregates removed in this embodiment, the initial wave velocity measurement value of the concrete is obtained through ultrasonic waves. Due to the influence of coarse aggregates, this initial measurement value cannot accurately reflect the sulfate erosion situation and needs to be corrected. Therefore, the CT image of the concrete in the plane where the ultrasonic measurement line is located is obtained again. According to the CT image, the proportion of coarse aggregates on the ultrasonic measurement line is obtained, and the coarse aggregate part and non - coarse aggregate part of the concrete are separated. According to the proportion of coarse aggregates and the wave velocity of the same ultrasonic waves in the coarse aggregates, the wave velocity correction value is obtained, so as to remove the influence of coarse aggregates on the wave velocity and obtain an accurate measurement value, solving the problem of ultrasonic wave velocity measurement of different components in the concrete specimen and the problem of the influence of different components on the wave velocity change after sulfate corrosion of the concrete specimen. And compared with using a single CT scan calculation, this test method only scans at the measurement line, greatly reducing the number of scans required, saving a large amount of costs, and combining ultrasonic velocity measurement, saving a large amount of calculation processes, improving the test efficiency, and ensuring the test accuracy at the same time.

[0036] In this embodiment, the specific steps of the test method are as follows:

[0037] 1. First, obtain the wave velocity of ultrasonic waves in coarse aggregates by preparing standard specimens, V 粗骨料 The specific obtaining steps are as follows:

[0038] S1: Prepare concrete standard specimens with the same mix ratio as that during the construction of the concrete to be tested, so that the standard specimens are consistent with the ideal state of the concrete. Cure the concrete standard specimens for 28 days with reference to the specimen curing method in the Standard for Test Methods of Long - term Performance and Durability of Ordinary Concrete (GB / T 50082 - 2009).

[0039] S2: After curing is completed, obtain the acoustic time T passed by the measuring line in at least one direction of the standard concrete specimen through ultrasonic waves. In this embodiment, obtain the acoustic time T passed by the measuring line in two mutually perpendicular directions X and Y in the same plane of the standard concrete specimen through ultrasonic waves. x and T y . The same plane can ensure that only one acquisition is performed during subsequent CT scanning, further reducing the required cost.

[0040] S3: As Figure 1 shown, obtain the CT image of the standard concrete specimen in the plane where the ultrasonic measuring line is located, process the CT image, and extract the coarse aggregate area based on the edge characteristics of the coarse aggregate. This image acquisition process can be carried out using a conventional CT scanning device, and the method of obtaining the area through the edge is also a relatively common image processing process, which can be executed by common image processing devices on the market, so it will not be elaborated here.

[0041] S4: As Figure 2 shown, mark the position of the measuring line in the CT image to obtain the length L of the coarse aggregate on the measuring line 粗骨料 and the length L of the non - coarse aggregate 非粗骨料 ;

[0042] S5: Obtain V through the following processing 粗骨料 :

[0043]

[0044] where V 非粗骨料 is the wave velocity value of the ultrasonic wave in the non - coarse aggregate part of the standard concrete specimen.

[0045] Since ultrasonic velocity measurement is performed in two directions in this embodiment, two unknowns V 粗骨料 and V 非粗骨料 can be obtained according to the following processing:

[0046]

[0047] In this embodiment, since the internal density of the newly prepared concrete specimen is good and the sound velocities of each part of the non - coarse aggregate are almost the same, V 非粗骨料 can be regarded as a constant value.

[0048] This embodiment is to eliminate the influencing factors between materials. The method of first preparing the specimen and then performing the test to obtain V 粗骨料 is adopted. In other embodiments, if the requirements for the test results are not high, V 粗骨料 can also be obtained by directly ultrasonic testing the coarse aggregate or other methods.

[0049] II. Obtain V 粗骨料After that, start to obtain the wave velocity correction value V of the concrete 修正值 :

[0050] S0: Core or cut samples from the concrete to be tested on-site. As Figure 3 shown, obtain cylindrical specimens; in other embodiments, specimens with other structures can also be used.

[0051] S1: Obtain the acoustic time passed by the measuring line in at least one direction of the cylindrical specimen of the concrete to be tested through ultrasonic waves, and combine it with the length L of the measuring line 测线 to obtain the initial wave velocity test value V of the concrete 测试初值 ; in this embodiment, the initial wave velocity test values V 测试初值x , V 测试初值y , V 测试初值z are obtained through ultrasonic waves in three mutually perpendicular directions X, Y, and Z of the cylinder; among the measuring lines in the three directions X, Y, and Z, one measuring line coincides with the axis of the cylindrical specimen, and the other two measuring lines are on the same section perpendicular to the axis and both pass through the center of the section, and this section can be located in the middle of the cylinder.

[0052] S2: Obtain the CT image of the concrete in the plane where the ultrasonic measuring line is located, process the CT image, and extract the coarse aggregate area based on the edge characteristics of the coarse aggregate;

[0053] S3: Mark the position of the measuring line in the CT image to obtain the length L of the coarse aggregate on the measuring line 粗骨料 , and according to obtain the length ratio ω of the coarse aggregate on the ultrasonic measuring line, and based on the ratio and the wave velocity of the same ultrasonic wave in the coarse aggregate, that is, the V 粗骨料 obtained in the previous step, obtain the wave velocity correction value V 修正值 ; in this embodiment, the wave velocity correction value V 修正值 is obtained through the following processing:

[0054]

[0055]

[0056]

[0057]

[0058] where t is the total time for the ultrasonic wave to pass through the measuring line, t 1 is the time for the ultrasonic wave to pass through the coarse aggregate, ω is the length ratio of the coarse aggregate on the ultrasonic measuring line, V 测试初值 is the initial wave velocity test value of the concrete obtained by the ultrasonic wave, V 粗骨料is the wave velocity value of the same ultrasonic wave in the coarse aggregate. Through the above treatment, the wave velocity correction values V 修正值x , V 修正值y , V 修正值z of the concrete cylinder specimen to be measured in the three directions X, Y, and Z can be obtained, so as to obtain the corrosion degrees of the concrete to be measured in the three directions.

[0059] In this embodiment, although the process describes the operations as sequential processing, many of the operations can be implemented in parallel, concurrently, or simultaneously. The order of the operations can be rearranged. The processing can be terminated when its operations are completed, but there can also be additional steps not included therein. The processing can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0060] The above is only the preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, the improvements and transformations obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. An ultrasonic testing method for sulfate corrosion of concrete that eliminates the influence of coarse aggregates, characterized in that: Obtain the initial value of the wave velocity of concrete through ultrasonic waves, obtain the CT image of the concrete in the plane where the ultrasonic wave measuring line is located, obtain the proportion of coarse aggregate on the ultrasonic wave measuring line based on the CT image, and obtain the wave velocity correction value based on the proportion of coarse aggregate and the wave velocity of the same ultrasonic wave in the coarse aggregate; obtain the wave velocity correction value V through the following processing 修正值 : Where ω is the proportion of the length of coarse aggregate on the ultrasonic measurement line, V 测试初值 is the initial wave velocity value obtained by ultrasonic waves for concrete, and V 粗骨料 is the wave velocity value of the same ultrasonic waves in coarse aggregate.

2. The ultrasonic testing method for sulfate corrosion of concrete that eliminates the influence of coarse aggregates according to claim 1, characterized in that, The wave velocity correction value V of the concrete 修正值 is obtained through the following steps: S1: Obtain the acoustic time passed by the measurement line in at least one direction of the concrete to be tested through ultrasonic waves, and combine it with the measurement line length L 测线 to obtain the initial wave velocity measurement value V of the concrete 测试初值 ; S2: Obtain the CT image of the concrete in the plane where the ultrasonic measuring line is located, process the CT image, and extract the coarse aggregate area based on the edge characteristics of the coarse aggregates; S3: Mark the position of the measurement line on the CT image to obtain the length L of the coarse aggregate on the measurement line 粗骨料 , and according to obtain the proportion ω of the length of the coarse aggregate on the ultrasonic measurement line S4: Obtain the wave velocity correction value V based on the proportion and the wave velocity of the same ultrasonic wave in the coarse aggregate 修正值 .

3. The ultrasonic testing method for sulfate corrosion of concrete that eliminates the influence of coarse aggregates according to claim 2, characterized in that, It further includes step S0: Core or cut samples from the concrete to be tested on site to obtain cylindrical specimens; And then, the initial wave velocity test values V 测试初值x , V 测试初值y , V 测试初值z are obtained in three mutually perpendicular directions X, Y, Z of the cylinder by ultrasonic waves; and finally, the wave velocity correction values V 修正值x , V 修正值y , V 修正值z in three directions X, Y, Z are obtained.

4. The ultrasonic testing method for sulfate corrosion of concrete that eliminates the influence of coarse aggregates according to claim 3, characterized in that: Among the measuring lines in the three directions X, Y, and Z, one measuring line coincides with the axis of the cylindrical specimen, and the other two measuring lines are on the same section perpendicular to the axis, and both pass through the center of the section.

5. The ultrasonic testing method for sulfate corrosion of concrete that eliminates the influence of coarse aggregates according to claim 4, characterized in that, The said V 粗骨料 is obtained by the following steps: S1: Prepare concrete standard specimens with the same mix ratio as when the concrete to be tested is constructed, and cure the specimens; S2: Obtain the acoustic time T passed by the measuring line in at least one direction of the concrete standard specimen through ultrasonic waves; S3: Obtain the CT image of the concrete standard specimen in the plane where the ultrasonic measuring line is located, process the CT image, and extract the coarse aggregate area based on the edge characteristics of the coarse aggregates; S4: Mark the position of the measurement line on the CT image to obtain the length L of the coarse aggregate on the measurement line 粗骨料 and the length L of non - coarse aggregate 非粗骨料 ; S5: Obtain V through the following processing 粗骨料 : Among them, V 非粗骨料 is the wave velocity value of ultrasonic wave in the non-coarse aggregate part of the standard concrete specimen.

6. The ultrasonic testing method for sulfate corrosion of concrete that eliminates the influence of coarse aggregates according to claim 5, characterized in that: Obtain the acoustic time T passed by the measuring line in two mutually perpendicular directions X and Y in the same plane of the standard concrete specimen through ultrasonic waves x and T y and obtain V according to the following processing 粗骨料 and V 非粗骨料 : 。

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