Method for detecting water penetration height in concrete penetration resistance test using capacitor

Abstract

The present application relates to the technical field of concrete impermeability detection, and particularly relates to a method for detecting water penetration height in concrete impermeability test by using a capacitor. The method for detecting water penetration height in concrete impermeability test by using a capacitor is proposed, and the water penetration height is tested by using the characteristics that the capacitor value changes with the water penetration height when the water penetration height of the concrete changes, and the water penetration height is used as the medium between the poles of the capacitor. The implementation of the present application can make the two tests of the step-by-step pressurization method and the water penetration height method be completed in one test, and the automatic detection can be completely realized without human intervention, so that the test time of the water penetration height method can be greatly saved, and the work efficiency and the detection data quality can be improved. The present application solves the defects of the complicated operation and the low efficiency of the water penetration height method in the prior art.

Description

[0001] This invention is a divisional application of the patent application with application number "2025102605242" filed on March 6, 2025, entitled "Method, Apparatus and System for Detecting Water Seepage Height in Concrete Permeability Test". Technical Field

[0002] This invention relates to the field of concrete impermeability testing technology, and in particular to a method for detecting the seepage height of concrete in an impermeability test using a capacitor. Background Technology

[0003] The main methods for testing the water permeability of concrete include the water penetration height method and the stepwise pressure method, which are used to test the water permeability resistance of ordinary concrete.

[0004] The preparation of specimens for the permeability height method must adhere to specific standards, such as strict regulations on the maximum nominal aggregate size, specimen dimensions, and flatness of the bearing surface. Specimens must be cured under standard curing conditions until the specified age is reached. Before testing, the specimens must be sealed by applying molten paraffin or similar material to the sides to ensure accuracy. The test begins at 0.1 MPa, increasing the pressure by 0.1 MPa every 8 hours until 3 out of 6 specimens show signs of permeability, at which point the test is terminated. The specimens removed from the permeability tester are placed on a press, with a 6m diameter steel strip placed at the center of each end face along the diameter direction, ensuring they are in the same vertical plane. The press is then activated, splitting the specimen in half longitudinally. After splitting, watermarks should be marked with a waterproof pen. Place the trapezoidal plate on the split surface of the specimen and use a steel ruler to measure the water seepage height at 10 equally spaced points along the watermark. The readings should be accurate to 1 mm. If a measuring point is blocked by the aggregate, the arithmetic mean of the water seepage heights at the two ends closest to the aggregate can be used as the water seepage height at that point.

[0005] The stepped pressure method is also used to determine the water permeability resistance of ordinary concrete. Specimen preparation, curing, and sealing are the same as the seepage height method. The test begins with low water pressure, gradually increasing the pressure and maintaining each pressure level for a certain time until the predetermined pressure is reached or obvious seepage is observed. The seepage situation at each pressure level, as well as the number of specimens that ultimately show no seepage, are recorded to calculate the concrete's impermeability grade.

[0006] In summary, both the seepage height method and the stepwise pressure method can evaluate the impermeability of concrete. After the seepage height method test is completed, the specimen is split in half along the longitudinal section using a press, and the seepage height value at 10 measuring points at equal intervals along the water mark is measured with a steel ruler. This method can accurately determine the seepage situation of each specimen and has higher reliability than the stepwise pressure method.

[0007] However, after the water seepage height method test is completed, it is time-consuming and laborious to use a press to split the specimen in half along the longitudinal section and then evaluate the water seepage situation, which to some extent restricts the widespread promotion of this method. Summary of the Invention

[0008] To overcome the shortcomings of the existing water seepage height method, which is complex to operate and inefficient, this invention proposes a method for detecting the water seepage height in concrete impermeability tests. This method enables rapid detection of water seepage height, avoids the cumbersome process of splitting the specimen with a press for measurement, effectively saves time and reduces costs.

[0009] The present invention proposes a method for detecting the seepage height in a concrete impermeability test. The concrete specimen and the seepage water inside it are used as the dielectric between the electrodes of a capacitor. A capacitance sensor is arranged around the concrete specimen to hold it in place. The capacitance sensor is insulated from the concrete specimen. Then, the seepage height is calculated based on the capacitance value.

[0010] Preferably, it is suitable for parallel plate capacitors, in which parallel plate capacitors are arranged horizontally vertically to clamp the concrete specimen during testing;

[0011] The method first combines the relationship between the capacitance value and the seepage height of the concrete specimen with the calibration sample, and records the seepage height calculated by combining the known capacitance value and the relationship as the seepage height fitting value, and records the seepage height calculated by combining the known capacitance value and the theoretical formula as the seepage height theoretical value; and constructs the ratio change curve of the seepage height fitting value and the seepage height theoretical value under different capacitance values ​​on the calibration sample.

[0012] Then, a parallel plate capacitor is used to test the concrete specimen to obtain the measured capacitance value. The theoretical value of the water seepage height of the concrete specimen is calculated, and the target ratio corresponding to the measured capacitance value is obtained by finding the ratio change curve. The product of the target ratio and the theoretical value of the water seepage height of the concrete specimen is calculated as the test result of the water seepage height of the concrete specimen.

[0013] Preferably, the relation is expressed as: h = a + b·ln(C) -4 Where a and b are the parameters to be fitted, C is the capacitance value, and h is the seepage height.

[0014] The preferred theoretical formula is expressed as follows:

[0015]

[0016] Among them, h s ε1 is the theoretical value of the seepage height; ε2 is the dielectric constant of the permeable concrete; H is the specimen height; S is the plate area; C is the capacitance value.

[0017] Preferably, a ring-shaped capacitor is used to detect the capacitance value of the concrete specimen. The two clamps of the ring-shaped capacitor are symmetrically arranged about the left and right sides of the concrete specimen and clamp it. The appropriate model for detecting the seepage height using the ring-shaped capacitor is as follows:

[0018]

[0019] Where h is the seepage height; ε1 is the dielectric constant of the seepage concrete; ε2 is the dielectric constant of the dry concrete; H is the specimen height; C is the measured capacitance value; α is the opening angle of the ring-shaped capacitor; and ξ is the correction coefficient.

[0020] Preferably, the correction coefficients are obtained by fitting the calibration samples.

[0021] Preferably, the value range of the slit opening angle α is [85°, 89.5°].

[0022] The present invention proposes a device for detecting the seepage height in a concrete impermeability test, comprising a capacitor structure, a capacitance testing instrument, and a computer; the computer stores a seepage height detection model corresponding to the capacitor structure, the capacitor structure uses a concrete specimen as a medium, the capacitance testing instrument is used to detect the capacitance value of the capacitor structure, and the computer obtains the capacitance value measured by the capacitance testing instrument and substitutes it into the seepage height detection model to calculate the seepage height.

[0023] When the capacitor structure is a parallel-plate capacitor consisting of two plates, the water seepage height detection model is as follows:

[0024] h = f s,C ·h s

[0025] Where h is the seepage height; h s To measure the capacitance value, substitute it into the theoretical model to calculate the theoretical value of the seepage height; let Cf s To characterize the ratio f of the fitted value to the theoretical value of the water seepage height in concrete specimens under different capacitance values s The correction function of the relation; f s,C Represents the correction function Cf s The ratio f corresponding to the upper detection capacitance value s ;

[0026] When the capacitor structure is a ring-shaped capacitor consisting of two clamping plates, the water seepage height detection model is as follows:

[0027]

[0028] Where h is the seepage height; ε1 is the dielectric constant of the seepage concrete; ε2 is the dielectric constant of the dry concrete; H is the specimen height; C is the measured capacitance value; α is the opening angle of the ring-shaped capacitor; and ξ is the correction coefficient.

[0029] The present invention proposes a system for detecting the seepage height in a concrete impermeability test, comprising a memory and a processor. The memory stores a computer program, and the processor is connected to the memory. The processor executes the computer program to implement the method for detecting the seepage height in a concrete impermeability test.

[0030] The present invention proposes a storage medium storing a computer program, which, when executed, is used to implement the method for detecting the seepage height in a concrete impermeability test.

[0031] The advantages of this invention are:

[0032] This invention proposes a method for detecting the seepage height in concrete permeability testing. It utilizes the characteristic that the capacitance of concrete, acting as the dielectric between the electrodes of a capacitor, changes with the seepage height to determine the seepage height. The implementation of this invention will allow both the step-by-step pressure method and the seepage height method to be completed in a single experiment, achieving fully automated testing without human intervention. This will significantly reduce the testing time for the seepage height method, improving work efficiency and the quality of test data.

[0033] This invention utilizes the characteristic that concrete specimens can be clamped by capacitors during concrete impermeability testing to perform capacitance testing, which is convenient and quick, eliminating the need to split the concrete for observation, thus improving the efficiency of concrete testing and reducing operating costs and difficulty.

[0034] This invention, taking into account the fact that concrete specimens are typically truncated cones, proposes two capacitor structures and capacitance measurement methods: a parallel plate capacitor and a ring-shaped capacitor. Corresponding water seepage height detection models are proposed for different capacitance measurement methods, providing multiple methods for capacitance testing of concrete specimens, facilitating selection based on environmental conditions; it also facilitates verification of test results through different testing methods. Attached Figure Description

[0035] Figure 1 This is a flowchart of a method for detecting the seepage height in a concrete impermeability test.

[0036] Figure 2 This is a schematic diagram of a parallel-plate capacitor.

[0037] Figure 3 This is a schematic diagram of the detection status of a parallel plate capacitor.

[0038] Figure 4 This is a schematic diagram of the detection status of a wraparound capacitor;

[0039] Figure 5 To show the angle;

[0040] Figure 6This is a test site for a parallel plate capacitor.

[0041] Figure 7 This is a display of the fitted function;

[0042] Figure 8 The detection error is shown in Table 2 of Example 1;

[0043] Figure 9 The detection error is shown in Table 3 of Example 1;

[0044] Figure 10 This is a test site for a wraparound capacitor.

[0045] Figure 11 The detection error is shown in Table 4 of Example 2;

[0046] Figure 12 The detection error is shown in Table 5 of Example 2;

[0047] Figure 13 The detection error is shown in Table 6 of Example 2. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] Reference Figure 1 This invention uses a concrete specimen and its internal seepage water as the dielectric between the electrodes of a capacitor. A dedicated capacitance sensor is placed around the periphery of the concrete specimen. When the seepage water height changes, the dielectric constant of the dielectric between the capacitor electrodes changes, resulting in a change in the capacitance value. Testing revealed that the change in capacitance value exhibits a linear relationship with the seepage height. Therefore, the seepage height in concrete impermeability tests can be quickly measured using this invention, avoiding the cumbersome process of splitting the specimen with a press, effectively saving time and reducing costs.

[0050] This invention provides two capacitor structures.

[0051] The first type of capacitor structure consists of vertically arranged, parallel plates 1, referred to as a parallel-plate capacitor, such as... Figure 3 As shown.

[0052] A parallel-plate capacitor is a fundamental and important electronic component, widely used in various circuits. Several key parameters related to the capacitance value C of a parallel-plate capacitor include: the relative permittivity ε of the inter-electrode insulating medium e.r The vacuum dielectric constant ε0, plate area S, and plate spacing d are detailed in the following references. Figure 2 These parameters collectively determine the capacitance of a capacitor, that is, its ability to store electrical charge. The formula for calculating the capacitance of a parallel-plate capacitor is:

[0053]

[0054] As can be seen from the above formula, the capacitance of a capacitor is mainly affected by the following factors:

[0055] 1. Different types of insulating media (such as air, mica, glass, etc.) will affect the dielectric constant;

[0056] 2. The area of ​​the upper and lower plates of the capacitor;

[0057] 3. The distance between the upper and lower plates of the capacitor.

[0058] When using a parallel-plate capacitor to test the water seepage height of a concrete specimen, the two plates 1 of the parallel-plate capacitor are arranged vertically on the two end faces of the concrete specimen, so that the two plates 1 are horizontally arranged and clamp the concrete specimen 2 vertically. The results are as follows. Figure 3 As shown. It is worth noting that the concrete specimen 2 is insulated from the two plates 1.

[0059] Thus, with a fixed plate area, the distance between the plates is equivalent to the height of the concrete specimen. When water seeps into the concrete specimen, it alters the overall dielectric constant of the inter-plate medium. The higher the water penetration height, the greater the water content, resulting in a higher overall dielectric constant and a larger capacitor capacitance. Conversely, the lower the water penetration height, the lower the water content, and the smaller the overall dielectric constant of the inter-plate medium.

[0060] When using a parallel plate capacitor to test the water seepage height, the water seepage height can be calculated using the water seepage height detection model shown in the following formula (1).

[0061]

[0062] Where h is the seepage height; ε1 is the dielectric constant of the seepage concrete; ε2 is the dielectric constant of the dry concrete; H is the height of the concrete specimen; C is the capacitance value measured by the parallel plate capacitor; S is the area of ​​the plate; let Cf s A correction function to characterize the ratio of fitted values ​​to theoretical values ​​of water seepage height in concrete specimens under different capacitance values; f s,C f represents the capacitance value when the capacitance is C. s Values.

[0063] ε1 and ε2 can be obtained by looking up a table.

[0064] Correction function Cf sThe acquisition of [the resource] includes the following steps.

[0065] S11. Construct the testing environment and determine the height H of the concrete specimen and the plate area S of the parallel plate capacitor. Use the parallel plate capacitor to measure the capacitance of the concrete specimen in the testing environment. The two plates of the parallel plate capacitor are set horizontally and clamp the concrete specimen from top to bottom. The plates are insulated from the concrete specimen.

[0066] S12. Obtain calibration samples (h, C) of concrete specimens. p ), where h is the water seepage height of the concrete specimen set during calibration, and C p The capacitance value is set at a water seepage height of h for the concrete specimen during calibration. Specifically, the capacitance of the concrete specimen can be measured first, and then the specimen can be split to measure the water seepage height to obtain the calibration sample (h, C). p );

[0067] S13. Fitting the seepage height h and calibration capacitance C based on the calibration sample. p The relationship is used as the fitting formula for the seepage height.

[0068] Specifically, in this embodiment, the fitting formula for the seepage height can be set as h=a+b·ln(C p ) -4 Thus, parameters a and b are fitted based on the calibrated samples.

[0069] S14. Calculate the calibration capacitance C according to the theoretical calculation formula. p The theoretical value h of the corresponding concrete specimen seepage height s ;

[0070]

[0071] Among them, h s ε1 is the theoretical value of the seepage height; ε2 is the dielectric constant of the permeable concrete; H is the specimen height; S is the plate area.

[0072] S15. Obtain the correction function Cf s That is, to construct the seepage height h and the theoretical height h s The ratio f s Regarding capacitor C p The correlation curve, f s =h / h s .

[0073] The second type of capacitor structure consists of two clamping plates 3 forming a ring-shaped capacitor as electrode plates. The ring-shaped capacitor is positioned around the outer periphery of the concrete specimen, with the two clamping plates 3 holding the specimen from the left and right sides and insulated from it. A gap is left between the two clamping plates 3, and the two clamping plates 3 are arranged symmetrically about the concrete specimen, as shown below. Figure 4As shown, the dashed line 4 represents the water level.

[0074] The second capacitor structure is equivalent to the first capacitor structure, and its influencing parameters are the same as those of a parallel-plate capacitor. When the water penetration height of the concrete specimen changes, the overall dielectric constant of the inter-electrode medium changes. The higher the water penetration height, the greater the water content, the greater the overall dielectric constant of the inter-electrode medium, and the larger the capacitor capacitance. Conversely, the same linear change occurs.

[0075] For cylindrical concrete specimens, the clamping plate 3 is set with an arc surface structure attached to the circumference of the concrete specimen. At this time, the water seepage height of the concrete specimen can be calculated according to the water seepage height detection model shown in the following formula (2).

[0076]

[0077] h is the seepage height; ε1 is the dielectric constant of the seepage concrete; ε2 is the dielectric constant of the dry concrete; H is the specimen height; C is the measured capacitance value; α is the opening angle of the ring-type capacitor, as shown in Figure 5; ξ is the correction coefficient, which can be obtained through sample fitting.

[0078] Specifically, the fitting method for the correction coefficient ξ is as follows: First, obtain the calibration samples (h, C) of the concrete specimens. p Then let C = C p Substitute the calibration sample into formula (2) to fit the correction coefficient ξ.

[0079] The above-mentioned seepage height detection model is verified in conjunction with specific embodiments below.

[0080] Example 1

[0081] In this embodiment, a parallel plate capacitor is used for measurement to verify formula (1).

[0082] In this embodiment, an acrylic simulated concrete specimen container is made. The internal volume of the container is the same as that of a standard concrete specimen, with a height of 150 mm, a bottom circle diameter of 185 mm, and an upper bottom circle diameter of 175 mm.

[0083] The experimental setup is as follows:

[0084] Capacitance testing instrument: test level is 1V, test frequency is 1kHz;

[0085] Parallel plate capacitor: The plate is made of aluminum sheet with an area of ​​300×300mm and a thickness of 2mm;

[0086] Container contents: sand and water;

[0087] In the experiment, the water level inside the container was separated by a thin film to control the water level line, i.e., the seepage height; the part above the film was dry sand, and the part below the film was a sand-water mixture.

[0088] The experimental procedure consisted of 5 steps.

[0089] Step 1: With no water in the acrylic specimen container, use a capacitance tester to measure and record the capacitance value at this time;

[0090] Step 2: Fill the acrylic specimen container with water to 1 / 4 of its volume, and use a capacitance tester to measure and record the capacitance value at this point.

[0091] Step 3: Fill the acrylic specimen container with water to 2 / 4 of its volume, and use a capacitance tester to measure and record the capacitance value at this point.

[0092] Step 4: Fill the acrylic specimen container with water to 3 / 4 of its volume, and use a capacitance tester to measure and record the capacitance value at this point.

[0093] Step 5: Fill the acrylic specimen container with water, use a capacitance tester to test the capacitance value at this time and record it.

[0094] First, perform data calibration. Repeat the above experiment, record the data twice, take the average, and then perform formula calculation. Figure 6 These are photos taken at 3 / 4 water level during this implementation.

[0095] The data for this scheme was calibrated, and the recorded data is shown in Table 1 below.

[0096] Table 1: Capacitance values ​​at various water levels

[0097] 1 0 8.158 2 37.5 8.995 3 75 10.878 4 112.5 15.307 5 150 49.177

[0098] By fitting the above calibration data, we obtain:

[0099] h = a + b ln(C) p ) -4

[0100] Determine the parameters a = 167.3, b = -3124.2. The calibration data and fitting function are as follows: Figure 7 As shown. In this embodiment, formula (1-1) is used to calculate different capacitance values ​​C. p The theoretical value of the water level is used to calculate different capacitance values ​​C. p The ratio of the actual water level to the theoretical water level is used to construct a correction function Cf. s .

[0101] In this embodiment, two more tests were conducted, data were collected, and the water level was calculated using the seepage height detection model shown in formula (1). The results are shown in Tables 2 and 3. Figure 8 , Figure 9 As shown.

[0102] Table 2: Statistics of Back-Calculation Errors in the First Experiment

[0103]

[0104] Table 3: Statistics of Back-Calculation Errors in the Second Experiment

[0105]

[0106]

[0107] As can be seen, the error in this embodiment is consistently below 3%, proving the reliability of the method.

[0108] Example 2

[0109] In this embodiment, a wraparound capacitor is used for measurement to verify formula (2).

[0110] The simulated concrete specimen container and capacitance testing instrument in this embodiment are as shown in Embodiment 1. The medium inside the container is sand and water. A thin membrane is set at the water level to isolate water seepage, so that the part above the membrane is dry sand and the part below the membrane is a mixture of sand and water.

[0111] The clamp 3 of the ring-shaped capacitor is an arc-shaped copper sheet attached to the outer periphery of the simulated concrete specimen container, with an area of ​​150×295mm and a thickness of 0.3mm. During the test, the opening angle α of the ring-shaped capacitor is 89°.

[0112] In this embodiment, the calibration sample (h, C) is first obtained. p Substituting into formula (2), the fitting correction coefficient ξ is 8.5; then the formula (2) is verified based on the experimentally measured capacitance value.

[0113] The experimental procedure is as follows.

[0114] Step 1: With no water in the acrylic specimen container, use a capacitance tester to measure and record the capacitance value at this time;

[0115] Step 2: Fill the acrylic specimen container with water to 1 / 4 of its volume, and use a capacitance tester to measure and record the capacitance value at this point.

[0116] Step 3: Fill the acrylic specimen container with water to 2 / 4 of its volume, and use a capacitance tester to measure and record the capacitance value at this point.

[0117] Step 4: Fill the acrylic specimen container with water to 3 / 4 of its volume, and use a capacitance tester to measure and record the capacitance value at this point.

[0118] Step 5: Fill the acrylic specimen container with water, use a capacitance tester to test the capacitance value at this time and record it.

[0119] Repeat the above experiment, record the data 3 times, and calculate the water level based on the measured capacitance value and formula (2). The results are shown in Tables 4-6. Figures 11-13 As shown.

[0120] Table 4: Statistics of the first test data in Example 2

[0121]

[0122] Table 5: Statistics of the Second Test Data in Example 2

[0123]

[0124] Table 6: Statistics of the Third Test Data in Example 2

[0125]

[0126]

[0127] The results of the three tests above show that the error using the sheathed capacitor test is consistently below 6%; however, from... Figures 11-13 It can be seen that the linear characteristics of the wraparound capacitor are more significant and superior to those of the planar capacitor, indicating that the wraparound capacitor is more suitable for practical applications.

[0128] Of course, those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, but also includes the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0129] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0130] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A method for detecting the seepage height in a concrete permeability test using a capacitor, characterized in that, The concrete specimen and its internal seepage water are used as the dielectric between the electrodes of a capacitor. A capacitance sensor is placed around the concrete specimen to hold it in place. The capacitance sensor is insulated from the concrete specimen. Then, the seepage height is calculated based on the capacitance value. A ring-shaped capacitor is used to test the capacitance of concrete specimens. The two clamps of the ring-shaped capacitor are symmetrically arranged about the left and right sides of the concrete specimen and hold it in place. The appropriate model for detecting water seepage height using a ring-shaped capacitor is as follows: in, This refers to the seepage height; The dielectric constant of permeable concrete; The dielectric constant of dry concrete; The height of the specimen; The measured capacitance value; The opening angle of the sheathed capacitor; This is a correction factor.

2. The method for detecting the seepage height of concrete in a permeability test using a capacitor as described in claim 1, characterized in that, The correction coefficients are obtained by fitting the calibration samples.

3. The method for detecting the seepage height of concrete in a permeability test using a capacitor as described in claim 1, characterized in that, Opening angle The value range is [85°, 89.5°].

4. A system for detecting the seepage height in a concrete impermeability test, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program, the processor is connected to the memory, and the processor is used to execute the computer program to implement the method for detecting the seepage height of concrete in a permeability test using a capacitor as described in any one of claims 1-3.

5. A storage medium, characterized in that, The device contains a computer program that, when executed, implements the method for detecting the seepage height of concrete in a permeability test using a capacitor, as described in any one of claims 1-3.

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