A method for determining the equivalent dielectric constant of a cement stabilized aggregate test specimen
Patent Information
- Application Number
- CN202610871434.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-16
- Publication Date
- 2026-11-03
AI Technical Summary
Traditional methods for determining the equivalent dielectric constant rely on idealized assumptions, making it difficult to accurately obtain the true value of cement-stabilized crushed stone specimens. Furthermore, measurements are only performed on a single component or a simple structure, resulting in significant discrepancies between the measurement results and the actual situation.
By acquiring CT images of cement-stabilized crushed stone specimens, preprocessing, segmenting, and classifying them, calculating the volume fraction of each component, determining whether cracks exist and making corrections, and constructing an equivalent dielectric constant solution equation in conjunction with a multiphase generalized dielectric mixing model, the interaction of the multiphase mixing system is fully considered.
It accurately reflects the electromagnetic properties of materials, reduces the deviation between measurement results and actual conditions, and provides equivalent dielectric constant calculation results that are closer to reality.
Smart Images
Figure CN123029276A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of equivalent dielectric constant determination technology, and in particular to a method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens. Background Technology
[0002] In the field of building materials science, cement-stabilized crushed stone is an important basic material widely used in the construction of roads, bridges and other projects. The accurate evaluation of its performance is crucial for the quality and durability of the project. Among them, the equivalent dielectric constant, as a key parameter reflecting the electromagnetic properties of the material, has important application value in non-destructive testing and material property analysis.
[0003] Traditional methods for determining the equivalent dielectric constant often have certain limitations. On the one hand, some methods rely on idealized assumptions, such as the uniform distribution of components within the material and the absence of microscopic defects. However, the actual internal structure of cement-stabilized crushed stone specimens is complex, containing multiphase components such as coarse aggregate, cement mortar, and pore air, and the distribution of these components is not uniform. Furthermore, the specimens may contain microscopic defects such as cracks. These factors significantly affect the material's equivalent dielectric constant, making it difficult for traditional methods to accurately obtain its true value. On the other hand, some existing measurement techniques may only measure the dielectric constant of a single component or a simple structure, failing to comprehensively consider the complex interactions of multiphase mixtures. For example, measuring only the dielectric constant of coarse aggregate or cement mortar ignores their combined effects in a mixed state and their interaction with pore air, resulting in significant deviations between the measurement results and the actual situation. Summary of the Invention
[0004] In view of this, the present invention proposes a method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, which can effectively solve the defects of the prior art, which rely on idealized assumptions, making it difficult to accurately obtain the true value, and the measurement results deviate significantly from the actual situation due to the measurement of dielectric constant only for a single component or simple structure.
[0005] The technical solution of this invention is implemented as follows:
[0006] A method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, specifically including:
[0007] Acquire CT images of the target cement-stabilized crushed stone specimen and preprocess the CT images;
[0008] The preprocessed CT images are segmented and classified to obtain the regions of three components: coarse aggregate, cement mortar, and pore air, and the volume fraction of each component is calculated.
[0009] Measure the dielectric constant of the coarse aggregate region and the cement mortar region;
[0010] Determine whether the target cement-stabilized crushed stone specimen has cracks. If so, correct the volume fraction of pore air based on the crack geometry parameters, and adjust the volume fraction of coarse aggregate and cement paste accordingly.
[0011] Based on the corrected cement mortar volume fraction, the corrected coarse aggregate volume fraction, the corrected pore air volume fraction, and the dielectric constants of the coarse aggregate region and the cement mortar region, an equivalent dielectric constant solution equation is constructed based on a multiphase generalized dielectric mixing model.
[0012] The equivalent dielectric constant is obtained by solving the equation for the equivalent dielectric constant.
[0013] As a further optional scheme of the method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, the segmentation and classification of the preprocessed CT images to obtain regions of three components: coarse aggregate, cement mortar, and pore air, specifically includes:
[0014] Feature extraction is performed on the preprocessed CT images to obtain multi-scale features and gray-level distribution features;
[0015] Based on the extracted multi-scale features and gray-level distribution features, a threshold segmentation algorithm is used to perform initial segmentation on the CT image to obtain the initial segmentation result.
[0016] The initial segmentation result is optimized using a region growing algorithm to obtain the optimized segmentation result;
[0017] Based on the optimized segmentation results, the accurate regions of the three components—coarse aggregate, cement mortar, and pore air—are obtained.
[0018] As a further optional embodiment of the method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, the calculation of the volume fraction of each component specifically includes:
[0019] Traverse the regions of the three components: coarse aggregate, cement mortar, and pore air, and count the number of pixels belonging to the coarse aggregate region, the number of pixels belonging to the cement mortar region, and the number of pixels belonging to the pore air region.
[0020] Obtain the total number of pixels in the CT image;
[0021] Based on the number of pixels in each component and the total number of pixels in the image, calculate the volume fraction of coarse aggregate, the volume fraction of cement mortar, and the volume fraction of pore air.
[0022] As a further alternative to the method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, a ring electrode capacitance method dielectric constant tester is used to measure the dielectric constant of the coarse aggregate region and the cement slurry region.
[0023] As a further optional embodiment of the method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, the correction of the pore air volume fraction based on crack geometry parameters specifically includes:
[0024] Calculate the air volume in the crack based on its length, width, and depth.
[0025] The corrected pore air volume fraction is obtained by superimposing the air volume in the cracks and the original pore volume.
[0026] As a further alternative to the method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, the multiphase generalized dielectric mixing model is a multiphase mixing model established by introducing the polarization influence coefficient of adjacent scatterers and the shape factor on the multiphase Maxwell-Garnett generalization model.
[0027] A system for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, comprising:
[0028] The image acquisition and preprocessing module is used to acquire CT images of the target cement-stabilized crushed stone specimen and to preprocess the CT images.
[0029] The segmentation and classification module is used to segment and classify the preprocessed CT images to obtain the regions of three components: coarse aggregate, cement mortar, and pore air, and to calculate the volume fraction of each component.
[0030] The measurement module is used to measure the dielectric constant of the coarse aggregate region and the cement slurry region;
[0031] The judgment and correction module is used to determine whether the target cement-stabilized crushed stone specimen has cracks. If so, the volume fraction of pore air is corrected according to the crack geometry parameters, and the volume fraction of coarse aggregate and cement paste are adjusted accordingly.
[0032] The equivalent dielectric constant solution equation construction module is used to construct the equivalent dielectric constant solution equation based on the modified cement mortar volume fraction, modified coarse aggregate volume fraction, modified pore air volume fraction, and dielectric constant of the coarse aggregate region and cement mortar region, based on the multiphase generalized dielectric mixing model.
[0033] The solver module is used to solve the equation for the equivalent dielectric constant to obtain the equivalent dielectric constant of the target cement-stabilized crushed stone specimen.
[0034] As a further alternative to the system for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, the multiphase generalized dielectric mixing model is a multiphase mixing model established by introducing the polarization influence coefficient of adjacent scatterers and the shape factor on the multiphase Maxwell-Garnett generalization model.
[0035] A computing device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of any of the above-described methods for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens.
[0036] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of any of the above-described methods for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens.
[0037] The beneficial effects of this invention are as follows: By acquiring and preprocessing CT images of the target cement-stabilized crushed stone specimen, the three-dimensional structural information inside the specimen can be presented intuitively and accurately. Based on this, the CT images are segmented and classified to accurately obtain the regions of the three types of components and calculate their volume fractions. Simultaneously, the presence of cracks is determined, and the volume fractions of pore air, coarse aggregate, and cement mortar are corrected according to the crack geometry parameters. This series of operations fully considers the actual component distribution and microscopic defects inside the specimen, breaking the limitations of traditional idealized assumptions and providing more realistic basic data for accurately calculating the equivalent dielectric constant. Furthermore, based on the corrected volume fractions of each component and the measured dielectric constant, an equivalent dielectric constant solution equation is constructed based on a multiphase generalized dielectric mixing model. This model combines the actual multiphase composition and structural characteristics inside the specimen, rather than being based on idealized assumptions, thus enabling a more realistic calculation. This method reflects the electromagnetic interactions within the material, effectively solving the problem of obtaining the true value of the equivalent dielectric constant due to idealized assumptions, making the calculation results more consistent with reality. Secondly, by measuring the dielectric constants of the coarse aggregate region and the cement slurry region, and comprehensively considering the influence of pore air, the volume fraction of each component is calculated. These actually measured dielectric constants and corrected volume fractions are incorporated into the solution equations of the multiphase generalized dielectric mixing model. This comprehensively considers the interactions and combined effects between the components in the multiphase mixed system. The solution equations based on the multiphase generalized dielectric mixing model can more accurately describe the electromagnetic response of the material in the multiphase mixed state, thereby effectively reducing the deviation between the measurement results and the actual situation caused by measuring only a single component or simple structure. This allows the final equivalent dielectric constant to more accurately reflect the true electromagnetic properties of the cement-stabilized crushed stone specimen. Attached Figure Description
[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0039] Figure 1 This is a flowchart illustrating a method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens according to the present invention.
[0040] Figure 2 This is a schematic diagram of the composition of a system for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens according to the present invention.
[0041] Figure 3 This is a schematic diagram of the composition of a computing device according to the present invention. Detailed Implementation
[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0043] refer to Figures 1 to 3 A method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, specifically including:
[0044] CT images of the target cement-stabilized crushed stone specimen were acquired and preprocessed.
[0045] Specifically, industrial CT scan tomographic image sequences of the target cement-stabilized crushed stone specimen are obtained. The images are preprocessed through grayscale transformation, noise reduction filtering, and contrast enhancement to reduce noise, improve boundary clarity, create conditions for threshold segmentation and region growing, and improve segmentation robustness.
[0046] The preprocessed CT image is segmented and classified to obtain regions of three components: coarse aggregate, cement mortar, and pore air, and the volume fraction of each component is calculated. In some embodiments, the segmentation and classification of the preprocessed CT image to obtain regions of three components—coarse aggregate, cement mortar, and pore air—specifically includes:
[0047] Feature extraction is performed on the preprocessed CT images to obtain multi-scale features and gray-level distribution features;
[0048] Based on the extracted multi-scale features and gray-level distribution features, a threshold segmentation algorithm is used to perform initial segmentation on the CT image to obtain the initial segmentation result.
[0049] The initial segmentation result is optimized using a region growing algorithm to obtain the optimized segmentation result;
[0050] Based on the optimized segmentation results, the accurate regions of the three components—coarse aggregate, cement mortar, and pore air—are obtained.
[0051] Specifically, feature extraction is performed on the preprocessed CT images to obtain multi-scale features and gray-scale distribution features. Multi-scale features can capture detailed information of the image at different scales, such as the general outline of coarse aggregate and its fine surface texture. Gray-scale distribution features reflect the gray value changes in different regions of the image, which is crucial for distinguishing regions with different material compositions. By extracting these rich features, a comprehensive and detailed image information foundation is provided for subsequent segmentation and classification, which helps to more accurately identify various components.
[0052] Secondly, based on the extracted multi-scale features and gray-scale distribution features, the threshold segmentation algorithm is used to perform initial segmentation of the CT image. The threshold segmentation algorithm has the characteristics of simple calculation and high efficiency. It can quickly divide the image into different regions according to the differences in features and preliminarily determine the region range that may belong to coarse aggregate, cement mortar and pore air.
[0053] Furthermore, a region-growing algorithm is employed to optimize the initial segmentation results. This algorithm merges adjacent pixels into the same region based on pixel similarity (such as grayscale values, feature similarity, etc.), effectively resolving issues like inaccurate boundaries and incomplete regions that may exist in the initial segmentation. Through optimization, the segmentation results better reflect the actual component distribution, improving the accuracy and reliability of the segmentation.
[0054] Furthermore, classifying based on the optimized segmentation results can more accurately determine the precise regions of the three components: coarse aggregate, cement mortar, and pore air. Accurate classification results are crucial for subsequent calculations of the volume fraction of each component. Only by accurately determining the regions of each component can the accuracy of the volume fraction calculation be guaranteed.
[0055] In some embodiments, calculating the volume fraction of each component specifically includes:
[0056] Traverse the regions of the three components: coarse aggregate, cement mortar, and pore air, and count the number of pixels belonging to the coarse aggregate region, the number of pixels belonging to the cement mortar region, and the number of pixels belonging to the pore air region.
[0057] Obtain the total number of pixels in the CT image;
[0058] Based on the number of pixels in each component and the total number of pixels in the image, the volume fraction of coarse aggregate, the volume fraction of cement mortar, and the volume fraction of pore air are calculated. Among these, the volume fraction of pore air is... Coarse aggregate volume ratio Cement mortar volume ratio =1- - .
[0059] Specifically, by traversing the regions of the three components, the number of pixels belonging to the coarse aggregate region, cement mortar region, and pore air region is counted respectively. This method conducts a detailed examination of each relevant region in the image, ensuring a comprehensive understanding of the pixel count of each component in the image. Obtaining the total number of pixels in the CT image provides an overall reference standard for calculating the volume ratio of each component. The total number of pixels, as the denominator, can reasonably reflect the proportion of the number of pixels of each component in the entire image.
[0060] Secondly, the volume ratio is calculated based on the number of pixels in each component and the total number of pixels in the image. This utilizes the principle that there is a certain proportional relationship between the number of pixels and the actual volume. In CT images, pixels are a digital representation of the actual object structure. Through this proportional calculation method, pixel information in the image can be converted into actual volume information, achieving a reasonable conversion from image data to physical quantities; the pore air volume ratio is explicitly given. Coarse aggregate volume ratio Cement mortar volume ratio Relationship =1- - This relationship not only conforms to the basic logic of material volume composition, but also simplifies the calculation process, avoids redundant calculations, and improves calculation efficiency.
[0061] The dielectric constant of the coarse aggregate region and the cement mortar region is measured. In some embodiments, a ring electrode capacitance method dielectric constant tester is used to measure the dielectric constant of the coarse aggregate region and the cement mortar region. Before the test, the instrument is calibrated in air (reading is 1), and contact measurement is performed under the condition that "the sample size is larger than the probe and the surface is flat". The average value of multiple points is taken as the dielectric constant value.
[0062] Specifically, the ring electrode of the ring electrode capacitance method dielectric constant tester is carefully placed on the surface of the coarse aggregate area, ensuring full contact between the ring electrode and the coarse aggregate, and that the contact surface is flat and without gaps. The tester's measurement function is then activated; the internal measurement system accurately measures the capacitance between the ring electrodes and records the measured capacitance value. According to the pre-set conversion formula between capacitance and dielectric constant of the tester. (in The dielectric constant of the coarse aggregate region. The conversion function (determined based on parameters such as the electrode structure and measurement frequency of the testing instrument) calculates the dielectric constant of the coarse aggregate region. After completing the measurement of the coarse aggregate area, remove the ring electrode from the coarse aggregate area and carefully place it on the surface of the cement grout area, ensuring that the ring electrode and cement grout are in full contact and the contact surface is good. Restart the measuring function of the tester to measure the capacitance value between the ring electrodes and record it. Using the same conversion formula for capacitance and dielectric constant. (in (where is the dielectric constant of the cement grout region), calculate the dielectric constant of the cement grout region. The measured dielectric constant of the coarse aggregate region and the dielectric constant of the cement mortar region Record it.
[0063] Thus, by employing a ring electrode capacitance method dielectric constant tester, better contact with the surface of the measured area can be achieved, adapting to the shape and characteristics of the cement-stabilized crushed stone specimen surface, ensuring the feasibility and accuracy of the measurement. Secondly, by taking the average of multiple points as the dielectric constant value, the potential non-uniformity of the dielectric constant within the measured area is fully considered. The internal structure of the coarse aggregate and cement slurry regions in the cement-stabilized crushed stone specimen is complex, and the dielectric constant may differ at different locations. Multi-point measurement and averaging can effectively reduce the influence of such local differences on the measurement results, improve the accuracy and reliability of the measurement data, and make the obtained dielectric constant value more representative of the average dielectric properties of the entire region.
[0064] Determine whether the target cement-stabilized crushed stone specimen has cracks. If so, correct the volume fraction of pore air based on the crack geometry parameters, and adjust the volume fraction of coarse aggregate and cement paste accordingly. In some embodiments, the correction of the volume fraction of pore air based on the crack geometry parameters specifically includes:
[0065] The air volume of the crack is calculated based on its length l, width w, and depth h. The specific formula is as follows: ;
[0066] When cracks appear in cement-stabilized crushed stone materials, air fills the cracks, increasing the volume of air in the pores of the cement-stabilized crushed stone materials. At this point, the volume fraction of the pore air... and coarse aggregate volume ratio for:
[0067] ;
[0068] ;
[0069] in, and The values represent the porosity and coarse aggregate volume fraction of the intact cement-stabilized crushed stone specimen, respectively; S and H represent the horizontal cross-sectional area and height of the intact cement-stabilized crushed stone specimen, respectively; and the total volume of the intact specimen is given by S and H. .
[0070] Specifically, based on the crack length l, width w, and depth h, the formula is used. The formula for calculating the air volume in cracks is simple and effective in converting the geometric dimensions of cracks into volume parameters, accurately quantifying the space occupied by cracks. When cracks appear in cement-stabilized crushed stone materials, the cracks are filled with air, increasing the volume of pore air in the material components. The formula corrects the pore air volume ratio by comprehensively considering the changes in the original pore air volume, crack air volume, and the total volume of the specimen, scientifically and reasonably reflecting the actual impact of cracks on the pore air volume ratio, making the corrected pore air volume ratio more consistent with the true state of the material. By adjusting the volume ratio of coarse aggregate accordingly, this adjustment process considers the influence of the space occupied by cracks on the volume ratio of coarse aggregate, ensuring the accuracy of the coarse aggregate volume ratio and making the relationship between the volume ratios of each component more reasonable.
[0071] Based on the cement mortar volume fraction, the corrected coarse aggregate volume fraction, the corrected pore air volume fraction, and the dielectric constants of the coarse aggregate region and the cement mortar region, an equivalent dielectric constant solution equation is constructed based on a multiphase generalized dielectric mixing model. In some embodiments, the multiphase generalized dielectric mixing model is a multiphase mixing model established by introducing the polarization influence coefficient of adjacent scatterers and the shape factor on the multiphase Maxwell-Garnett generalization model.
[0072] Specifically, based on the generalized dielectric mixing model, with the continuous phase cement mortar as the background medium, and the scattering coarse aggregate and air in the pores uniformly distributed in the background medium, the dielectric mixing theoretical model of cement-stabilized crushed stone material is as follows:
[0073] ;
[0074] in, Expressed as the relative permittivity of air, Expressed as the relative permittivity of cement mortar;
[0075] The volume fraction of cement-stabilized crushed stone materials consisting of pore air, coarse aggregate, and cement paste. , and They are respectively:
[0076] ;
[0077] ;
[0078] ;
[0079] In practical engineering, the morphologies of coarse aggregate and pores in cement-stabilized crushed stone mixtures are complex and varied, differing significantly from spherical shapes. Therefore, it is necessary to optimize the component morphology factor u, and considering the polarization effect of adjacent scatterers (v=2), a general dielectric mixing model for intact cement-stabilized crushed stone materials is derived as follows:
[0080] ;
[0081] ;
[0082] ;
[0083] in, Expressed as the relative permittivity of cement-stabilized crushed stone, It is expressed as the relative permittivity of coarse aggregate.
[0084] A general dielectric mixing model for cement-stabilized crushed stone mixtures is given, which can be converted into a cubic equation for the relative permittivity of the mixture. The estimated relative permittivity of the cement-stabilized crushed stone mixture is the real solution of this equation. The coefficients a, b, c, and d in the equation are represented as follows:
[0085] ;
[0086] ;
[0087] ;
[0088] ;
[0089] ;
[0090] To better determine the shape factor u of the phase scattering components applicable to cement-stabilized crushed stone mixtures, based on the general dielectric mixing model and its real solution for cement-stabilized crushed stone mixtures, different shape factor values were taken at intervals of 0.1. Based on 42 sets of indoor measured data, the estimated relative permittivity of intact cement-stabilized crushed stone specimens with different crack widths was calculated. It was found that when the shape factor u = 1, the average relative error of the relative permittivity of the cement-stabilized crushed stone specimens was the smallest, with a value of 3.47%. Substituting the shape factor u = 1 into the general dielectric mixing model, an optimized dielectric mixing model for cement-stabilized crushed stone mixtures can be obtained.
[0091] .
[0092] The equivalent dielectric constant is obtained by solving the equation for the equivalent dielectric constant.
[0093] Specifically, the equation is based on a multiphase generalized dielectric hybrid model, which has wide application and acceptance in describing the dielectric properties of multiphase hybrid materials. The solution equation derived from this model is scientific and reliable, and can more realistically simulate the dielectric response of cement-stabilized crushed stone specimens under electromagnetic field. By solving the equation, the equivalent dielectric constant of the target cement-stabilized crushed stone specimen can be obtained. Since the equation fully considers various key factors and is based on a reasonable model, the obtained equivalent dielectric constant can more accurately reflect the overall electromagnetic properties of the specimen.
[0094] Example: Verification of cement-stabilized crushed stone specimens for a highway base course:
[0095] This embodiment verifies the accuracy and superiority of the equivalent dielectric constant determination method described in this invention by conducting a series of experiments on the cement-stabilized crushed stone material used in the base layer of a certain highway.
[0096] Step 1. Experimental preparation and specimen preparation:
[0097] Raw materials: Continuously graded machine-made granite aggregate (particle size 0~31.5mm) and P.O42.5 ordinary Portland cement were selected. Trial mixes were conducted based on the gradation curve of the dense aggregate, and the optimum moisture content was determined to be 5.1%, with a cement dosage of 5%.
[0098] Specimen molding: Cylindrical cement-stabilized crushed stone specimens with a diameter of 150 mm and a height of 150 mm were prepared by static compaction. To simulate different compaction states, different vibration compaction energies were applied to mold six specimen groups with different dry densities (corresponding to different initial porosities). Each group contained three parallel specimens, for a total of 18 basic specimens.
[0099] Damage simulation: Regular cracks of different widths (cracks running through the entire specimen) were prefabricated in the center of the specimen. The crack widths w were 0 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm and 7 mm, respectively, to simulate different degrees of base layer cracking damage.
[0100] Step 2. Data Acquisition and Preprocessing:
[0101] Component dielectric constant measurement: The relative dielectric constant of the raw aggregate and the cement mortar test block after 28 days of curing were directly measured using a Percometer dielectric constant tester (SF-177 probe). The relative dielectric constant of the coarse aggregate was measured to be 8.63, and the relative dielectric constant of the cement mortar was measured to be 5.21.
[0102] CT structural analysis: Each specimen was scanned using an industrial CT system to obtain its internal tomographic image sequence.
[0103] Image processing and volume fraction calculation: The CT images were subjected to grayscale transformation, denoising and contrast enhancement. Threshold segmentation and region growing algorithms were performed using Matlab to extract the pixel distribution of coarse aggregate, cement mortar and pore air, and the true volume fraction of each component was calculated.
[0104] Volume ratio correction: For specimens with precast cracks, the volume ratio of pore air and coarse aggregate is corrected in real time using the formula of this invention based on the crack geometry parameters (length l, width w, depth h).
[0105] Step 3. Model building and validation results:
[0106] Based on 42 sets of measured sample data (covering 6 types of density and 7 types of crack width), detailed data are shown in Tables 1-6. The optimal parameters of the multiphase generalized dielectric mixing model were determined by regression solution.
[0107] Figure 1. Volume and dielectric properties of cement-stabilized crushed stone specimen group 1 (initial porosity 2.11%):
[0108] Figure 2. Volume and dielectric properties of cement-stabilized crushed stone specimen group 2 (initial porosity 3.63%):
[0109] Figure 3. Volumetric and dielectric properties of cement-stabilized crushed stone specimen group 3 (initial porosity 5.42%):
[0110] Figure 4 shows the volumetric and dielectric properties of cement-stabilized crushed stone specimen group 4 (initial porosity 7.04%).
[0111] Figure 5. Volumetric and dielectric properties of cement-stabilized crushed stone specimen group 5 (initial porosity 8.76%):
[0112] Figure 6. Volumetric and dielectric properties of cement-stabilized crushed stone specimen group 5 (initial porosity 9.88%):
[0113] Parameter optimization: Experiments showed that the error between the model prediction and the measured value was minimized when the shape factor u of the component phase scatterer was 1.
[0114] Error analysis: The estimated equivalent dielectric constant obtained by using the optimized model of this invention has an average relative error (MRE) of only 3.47% and an average absolute error (MAE) of 0.235.
[0115] Comparative Validation: This method is compared with the traditional Polder-van Santen and Rayleigh models. The results are shown in the table below:
[0116] Step 4. Conclusion:
[0117] Experimental results show that the optimized model proposed in this invention has significantly better prediction accuracy than the traditional model when dealing with base materials with high porosity or wide cracks (≥4mm). Especially in the service crack state commonly seen in cement-stabilized crushed stone, this method can more accurately reflect the true electromagnetic properties inside the material, providing reliable parameter support for the quality inspection of road base.
[0118] A system for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, comprising:
[0119] The image acquisition and preprocessing module is used to acquire CT images of the target cement-stabilized crushed stone specimen and to preprocess the CT images.
[0120] The segmentation and classification module is used to segment and classify the preprocessed CT images to obtain the regions of three components: coarse aggregate, cement mortar, and pore air, and to calculate the volume fraction of each component.
[0121] The measurement module is used to measure the dielectric constant of the coarse aggregate region and the cement slurry region;
[0122] The judgment and correction module is used to determine whether the target cement-stabilized crushed stone specimen has cracks. If so, the volume fraction of pore air is corrected according to the crack geometry parameters, and the volume fraction of coarse aggregate and cement paste are adjusted accordingly.
[0123] The equivalent dielectric constant solution equation construction module is used to construct the equivalent dielectric constant solution equation based on the modified cement mortar volume fraction, modified coarse aggregate volume fraction, modified pore air volume fraction, and dielectric constant of the coarse aggregate region and cement mortar region, based on the multiphase generalized dielectric mixing model.
[0124] The solver module is used to solve the equation for the equivalent dielectric constant to obtain the equivalent dielectric constant of the target cement-stabilized crushed stone specimen.
[0125] In some embodiments, the multiphase generalized dielectric mixing model is a multiphase mixing model established by introducing the polarization influence coefficient of adjacent scatterers and the shape factor on the multiphase Maxwell-Garnett generalization model.
[0126] A computing device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of any of the above-described methods for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens.
[0127] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of any of the above-described methods for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens.
[0128] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, characterized in that, Specifically, it includes: Acquire CT images of the target cement-stabilized crushed stone specimen and preprocess the CT images; The preprocessed CT images are segmented and classified to obtain the regions of three components: coarse aggregate, cement mortar, and pore air, and the volume fraction of each component is calculated. Measure the dielectric constant of the coarse aggregate region and the cement mortar region; Determine whether the target cement-stabilized crushed stone specimen has cracks. If so, correct the volume fraction of pore air based on the crack geometry parameters, and adjust the volume fraction of coarse aggregate and cement paste accordingly. Based on the corrected cement mortar volume fraction, the corrected coarse aggregate volume fraction, the corrected pore air volume fraction, and the dielectric constants of the coarse aggregate region and the cement mortar region, an equivalent dielectric constant solution equation is constructed based on a multiphase generalized dielectric mixing model. The equivalent dielectric constant is obtained by solving the equation for the equivalent dielectric constant.
2. The method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens according to claim 1, characterized in that, The preprocessed CT images are segmented and classified to obtain regions consisting of three components: coarse aggregate, cement mortar, and pore air. Specifically, this includes: Feature extraction is performed on the preprocessed CT images to obtain multi-scale features and gray-level distribution features; Based on the extracted multi-scale features and gray-level distribution features, a threshold segmentation algorithm is used to perform initial segmentation on the CT image to obtain the initial segmentation result. The initial segmentation result is optimized using a region growing algorithm to obtain the optimized segmentation result; Based on the optimized segmentation results, the accurate regions of the three components—coarse aggregate, cement mortar, and pore air—are obtained.
3. The method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens according to claim 2, characterized in that, The calculation of the volume fraction of each component specifically includes: Traverse the regions of the three components: coarse aggregate, cement mortar, and pore air, and count the number of pixels belonging to the coarse aggregate region, the number of pixels belonging to the cement mortar region, and the number of pixels belonging to the pore air region. Obtain the total number of pixels in the CT image; Based on the number of pixels in each component and the total number of pixels in the image, calculate the volume fraction of coarse aggregate, the volume fraction of cement mortar, and the volume fraction of pore air.
4. The method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens according to claim 3, characterized in that, The dielectric constant of the coarse aggregate region and the cement mortar region was measured using a ring electrode capacitance method dielectric constant tester.
5. The method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens according to claim 4, characterized in that, The correction of the pore air volume fraction based on crack geometry parameters specifically includes: Calculate the air volume in the crack based on its length, width, and depth. The corrected pore air volume fraction is obtained by superimposing the air volume in the cracks and the original pore volume.
6. The method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens according to claim 5, characterized in that, The multiphase generalized dielectric mixing model is a multiphase mixing model established by introducing the polarization influence coefficient of adjacent scatterers and the shape factor on the multiphase Maxwell-Garnett generalization model.
7. A system for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens, characterized in that, include: The image acquisition and preprocessing module is used to acquire CT images of the target cement-stabilized crushed stone specimen and to preprocess the CT images. The segmentation and classification module is used to segment and classify the preprocessed CT images to obtain the regions of three components: coarse aggregate, cement mortar, and pore air, and to calculate the volume fraction of each component. The measurement module is used to measure the dielectric constant of the coarse aggregate region and the cement slurry region; The judgment and correction module is used to determine whether the target cement-stabilized crushed stone specimen has cracks. If so, the volume fraction of pore air is corrected according to the crack geometry parameters, and the volume fraction of coarse aggregate and cement paste are adjusted accordingly. The equivalent dielectric constant solution equation construction module is used to construct the equivalent dielectric constant solution equation based on the modified cement mortar volume fraction, modified coarse aggregate volume fraction, modified pore air volume fraction, and dielectric constant of the coarse aggregate region and cement mortar region, based on the multiphase generalized dielectric mixing model. The solver module is used to solve the equation for the equivalent dielectric constant to obtain the equivalent dielectric constant of the target cement-stabilized crushed stone specimen.
8. The system for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens according to claim 7, characterized in that, The multiphase generalized dielectric mixing model is a multiphase mixing model established by introducing the polarization influence coefficient of adjacent scatterers and the shape factor on the multiphase Maxwell-Garnett generalization model.
9. A computing device, characterized in that, The method includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens as described in any one of claims 1-6.
10. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the steps of the method for determining the equivalent dielectric constant of cement-stabilized crushed stone specimens as described in any one of claims 1-6.