A rapid method for determining the mixing uniformity of water-based polymer-stabilized graded crushed stone.

Abstract

This invention discloses a rapid method for determining the mixing uniformity of water-based polymer-stabilized graded crushed stone, relating to the field of road engineering material testing and construction quality control technology. This invention adds an identifiable tracer component without significantly altering the film-forming and dispersion characteristics of the water-based polymer, preparing a tracer polymer liquid which is then mixed with graded crushed stone. Through multi-point sampling, single-particle approximate single-layer slab preparation, and image acquisition under uniform optical conditions, and after background correction, threshold segmentation, particle identification, and region statistics, the surface coating rate, region dispersion coefficient, exposed particle rate, and agglomeration index are calculated and compared with preset thresholds, achieving rapid quantitative determination of mixing uniformity and process feedback adjustment.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering material testing and construction quality control, and specifically to a rapid determination method for the mixing uniformity of water-based polymer stabilized graded crushed stone. Background Technique

[0002] As a road base material, water-based polymer stabilized graded crushed stone is usually mixed by the method of adding a low dosage of liquid polymer externally. Due to the low dosage of the water-based polymer and the insignificant difference in the appearance of particles after mixing, it is difficult to directly, rapidly, and quantitatively judge by the naked eye whether the distribution of the polymer on the surface of the graded crushed stone particles is uniform during the on-site production and indoor sample preparation processes.

[0003] The existing quality control methods mainly rely on empirical means such as extending the mixing time, changing the liquid spraying method, and adjusting the liquid adding sequence, or indirectly infer the mixing quality through posteriori tests such as compressive strength, resilient modulus, and water stability after forming. Such methods have problems of lagging determination, untimely feedback, insufficient batch representativeness, and difficulty in rapid on-site closed-loop adjustment.

[0004] On the other hand, although methods such as CT, slice image analysis, and fluorescence microscopic observation can obtain high-resolution internal structure information, these methods generally have deficiencies such as high equipment cost, cumbersome sample processing, long detection period, and inapplicability to rapid on-site quality control. Especially for the low-dosage externally added water-based polymer system, in engineering, there is a greater need for a detection method that uses the apparent coating uniformity on the exposed surface as a proxy index, can rapidly determine whether it is qualified, and inversely guide the process adjustment, rather than a microscopic mechanism characterization method aimed at measuring the true three-dimensional surface full coverage of particles.

[0005] Therefore, how to construct a mixing uniformity detection method that neither significantly changes the film-forming and dispersion characteristics of the water-based polymer, can visualize its distribution state, and realizes rapid, objective, and quantitative evaluation by combining standardized image acquisition, image processing, and multi-index criteria has become an urgent technical problem in this field. Summary of the Invention

[0006] The purpose of the present invention is to provide a rapid determination method for the mixing uniformity of water-based polymer stabilized graded crushed stone to solve the technical problems proposed in the background technique.

[0007] To achieve the above purpose, the present invention provides the following technical solution: A rapid determination method for the mixing uniformity of water-based polymer stabilized graded crushed stone, including the following steps:

[0008] S1: Select a water-based polymer and graded crushed stone, and add an identifiable tracer component to the water-based polymer on the premise of not significantly changing the film-forming and dispersion characteristics of the water-based polymer to prepare a tracer polymer liquid;

[0009] S2: Spray the tracer polymer liquid or add it to the graded crushed stone according to the preset polymer dosage and water content for mechanical mixing to obtain the mixture to be tested;

[0010] S3: Extract multiple samples from different spatial locations of the mixture to be tested, and lay each sample flat on the observation carrier so that the particles are in a state of near-single-layer exposure.

[0011] S4: Acquire images of the sample under uniform optical conditions;

[0012] S5: Perform background correction, tracer-sensitive channel extraction, particle projection region identification, threshold segmentation and noise removal on the acquired image to obtain the effective tracer coverage area, the high-brightness enrichment area and the analyzable particle projection area.

[0013] S6: Divide the processed image into several statistical regions and calculate the surface coverage rate CR, regional dispersion coefficient CV, exposed particle rate UR, and aggregation index AI respectively. Among them, CR is the ratio of the effective tracer coverage area to the analyzable particle projection area, CV is the coefficient of variation of the local coverage rate of each statistical region, UR is the proportion of the number of particles with a coverage rate lower than the minimum effective coverage rate threshold to the total number of particles, and AI is the proportion of the area of ​​the bright enriched region to the total area of ​​the effective tracer coverage area.

[0014] S7: Compare CR, CV, UR and AI with preset thresholds respectively. When CR is not lower than the preset lower limit and CV, UR and AI are not higher than their respective upper limits, the uniformity of the mixture to be tested is deemed to be qualified. Otherwise, it is deemed unqualified, and at least one of the following should be adjusted: mixing time, spraying method, spraying sequence, polymer dilution ratio or mixing equipment parameters, and then retested.

[0015] Furthermore, the tracer group includes at least a fluorescent tracer, a visible light colorimetric agent, and a near-infrared responsive tracer;

[0016] The amount of the tracer component added is 0.05% to 0.50% of the mass of the water-based polymer.

[0017] Furthermore, the unified optical conditions include at least keeping the excitation light source wavelength, illumination angle, camera-sample distance, exposure parameters, and background plate reflectivity consistent.

[0018] Furthermore, there are no fewer than four sample points, and each sample is taken from a different spatial location of the mixture to be tested. The different spatial locations are representative spatial locations with different flow trajectories, and the different spatial locations include at least the surface layer, the middle layer, the bottom layer, and the discharge port.

[0019] Furthermore, the processed image is divided into 9 to 25 statistical regions of approximately equal area.

[0020] Furthermore, the threshold segmentation includes at least the Otsu method, the adaptive threshold method, and the pre-calibrated fixed threshold method;

[0021] The background correction employs one or more of the following: background image subtraction, flat field correction, top-hat transformation, or rolling ball background subtraction.

[0022] Furthermore, the calculation of the exposed particle rate UR includes particle segmentation, which is accomplished through connected component analysis;

[0023] When there is contact between particles, distance transformation and watershed algorithm are used for particle separation.

[0024] Furthermore, the highlighted enriched regions are defined as regions whose average intensity is not lower than the clustering recognition threshold. And the area of ​​the connected region is not less than the minimum clustered connected area threshold. The connected components, where , To effectively trace coverage and identify thresholds.

[0025] Furthermore, the preset threshold must at least satisfy the following settings:

[0026] The lower limit for surface coating rate is 80%–90%; the upper limit for regional dispersion coefficient is 10%–15%; the upper limit for exposed particle rate is 5%–10%; and the upper limit for aggregation index is 8%–12%.

[0027] For multiple sample points in the same batch, the arithmetic mean of the surface coating rate of each sample point is taken as the batch surface coating rate, and the maximum value of the regional dispersion coefficient, exposed particle rate and aggregation index of each sample point is taken as the batch representative value.

[0028] The method is used for the preparation of indoor specimens of water-based polymer-stabilized graded crushed stone, optimization of large-scale mixing process, quality control at construction sites, or monitoring of mixing uniformity in demonstration projects.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. This invention, without significantly altering the basic film-forming and dispersion characteristics of water-based polymers, achieves visualization of the distribution state of low-dosage polymers through tracer components, solving the industry pain point that the polymer coating situation cannot be identified by the naked eye. For the first time, it realizes direct and quantitative evaluation of the uniformity of stable graded crushed stone mixing of water-based polymers without relying on post-test performance tests.

[0031] 2. This invention uses the apparent uniformity of particle surface coating as an engineering proxy indicator, eliminating the need for sample slicing, CT scanning, or microscopic observation. The detection process is simple, has a low operating threshold, and a short detection cycle. A single batch of tests can be completed within 15 minutes. It is suitable for rapid sample preparation and quality control in indoor laboratories, as well as meeting the real-time quality control needs of plant mixing and construction sites, filling the gap in on-site rapid testing technology for this material.

[0032] 3. This invention constructs a joint evaluation system of four core indicators: surface coating rate, regional dispersion coefficient, exposed particle rate, and agglomeration index. It can accurately distinguish four different mixing failure modes: insufficient overall coating, uneven regional distribution, excessive missing particles, and local agglomeration and enrichment. This provides a direct quantitative basis for targeted optimization of the mixing process, rather than a single qualified / unqualified judgment.

[0033] 4. This invention establishes a closed-loop quality control process from detection, judgment, process adjustment to re-inspection, which can quickly complete the iterative optimization of the mixing process. It solves the problem of large dispersion of mechanical properties and unstable engineering quality caused by uneven mixing of water-based polymer stabilized graded crushed stone from the source, and significantly improves the stability and comparability of indoor test data, as well as the quality reliability of engineering applications.

[0034] 5. This invention has low requirements for testing equipment. Only a portable excitation light source, high-definition acquisition equipment, and conventional image processing software are needed to complete all the testing. No large precision instruments are required, the equipment investment cost is low, and it is easy to promote and apply in engineering sites. It has significant economic benefits and engineering practical value. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0036] This invention provides a rapid method for determining the mixing uniformity of water-based polymer-stabilized graded crushed stone, specifically a rapid method for determining the mixing uniformity of water-based polymer-stabilized graded crushed stone based on tracer imaging and image analysis, in order to solve the technical problem that existing methods are difficult to rapidly, objectively, and quantitatively evaluate the distribution uniformity of externally added water-based polymers in graded crushed stone.

[0037] A further objective of this invention is to: provide quantitative basis for optimizing the large-scale mixing process of water-based polymer-stabilized graded crushed stone; provide batch access criteria for indoor specimen preparation; provide rapid detection and feedback means for on-site quality control; and improve the stability and comparability of subsequent mechanical property test and engineering application data through a closed-loop process of detection, judgment, adjustment, and re-inspection.

[0038] A rapid method for determining the mixing uniformity of water-based polymer-stabilized graded crushed stone includes the following steps:

[0039] S1: Preparation of test subjects

[0040] The target graded crushed stone and water-based polymer were selected. The graded crushed stone is the actual production material to be used in the road base layer; the water-based polymer is the polymer binder used in construction mixing.

[0041] Without significantly altering the film-forming and dispersion properties of the water-based polymer, a predetermined proportion of identifiable tracer components is added to the water-based polymer to prepare a tracer polymer solution. The tracer component is preferably one or more of a fluorescent tracer, a visible light colorimetric agent, or a near-infrared responsive tracer compatible with the water-based polymer.

[0042] S2: Mixture Preparation

[0043] According to the preset polymer dosage, water content and mixing process, the tracer polymer liquid is sprayed or added to graded crushed stone for mechanical mixing to obtain the mixture to be tested.

[0044] The mixing process parameters shall include at least one of the following: mixing time, mixing speed or mixing intensity, spraying method, spraying sequence, whether to add liquid in batches, and polymer dilution ratio.

[0045] S3: Sampling and Plating

[0046] After mixing is completed, multiple sample points are extracted from the mixture to be inspected according to the preset sampling rules. The sample points cover different spatial locations of the mixture.

[0047] Each sample is evenly spread on the observation carrier, so that the particles are in a state of near-single-layer exposure, reducing misjudgments caused by particles occluding each other and multiple layers stacking. The observation carrier is preferably a low-reflection, dark background plate.

[0048] S4: Image Acquisition

[0049] In a closed or semi-closed low background light environment, the sample is irradiated with a specific wavelength excitation light source matched with the tracer component, and an image acquisition device is used to acquire images of the sample surface.

[0050] Image acquisition conditions should at least maintain the following consistency: consistent light source wavelength and illumination angle; consistent distance between camera and sample; consistent exposure time, white balance, gain, and resolution; and consistent background color and reflectivity.

[0051] S5: Image Processing

[0052] The acquired images are subjected to background correction, tracer-sensitive channel extraction, particle projection region identification, threshold segmentation, and noise removal to identify the effective tracer coverage area of ​​the polymer, the particle projection area, and the high-brightness enrichment area.

[0053] Background correction can be achieved by subtracting the original image from the background reference image. The background correction formula is as follows:

[0054]

[0055] in, For the original acquired image in pixels The grayscale value or channel intensity value at that location; The corresponding pixel values ​​of the background reference image acquired under the same optical conditions; This represents the image intensity value after background correction.

[0056] Threshold segmentation preferably employs the Otsu method, adaptive thresholding, or a pre-calibrated fixed thresholding method. When using the adaptive thresholding method, the local threshold can be expressed as:

[0057]

[0058] in, For pixels Local threshold at; This is the preset average grayscale value within a local window; The standard deviation of grayscale within a preset local window; These are empirical correction coefficients.

[0059] After image segmentation, noise is preferably removed by median filtering, morphological opening and closing operations, hole filling, and small connected component removal; for particles with slight contact, connected component analysis combined with the watershed algorithm is preferred for particle separation.

[0060] The processed image is divided into several statistical regions, preferably into 9-25 grid regions of approximately equal area, in order to calculate the local coverage index within each statistical region.

[0061] S6: Calculation of uniformity index

[0062] The surface coating rate referred to in this invention is essentially the apparent coating rate of the exposed surface. Let the processed image be divided into m statistical regions, and the analyzable particle projection area of ​​the j-th statistical region be... The effective tracking coverage area is The local coverage rate of this area is... for:

[0063]

[0064] 1. Surface coating rate CR

[0065]

[0066] in, The total area of ​​effective tracer coverage within the entire image; This represents the total projected area of ​​analyzable particles within the entire image.

[0067] 2. Regional Discreteness Coefficient (CV)

[0068] The mean local coverage rate of each statistical region is:

[0069]

[0070] The regional dispersion coefficient is:

[0071]

[0072] in, This represents the average local coverage rate. Used to reflect the degree of fluctuation in coverage rate between different regions The smaller the value, the more uniform the regions.

[0073] 3. Exposed Particle Rate (UR)

[0074] Let N be the total number of particles identified after particle segmentation, and let the projected area of ​​the i-th particle be... Its effective tracer coverage area is Then the particle coating rate of the particle for:

[0075]

[0076] The exposed particle rate is defined as:

[0077]

[0078] in, For particles with a coating rate lower than the minimum effective coating rate threshold The number of particles; The minimum effective coating rate threshold for particles is preferably 20%–30%.

[0079] 4. Reunion Index AI

[0080] Suppose there are K bright polymer enriched connected regions in total, and the area of ​​the kth bright polymer enriched connected region is... The total area of ​​highlight enrichment for:

[0081]

[0082] The reunion index is defined as:

[0083]

[0084] Among them, the preferred high-brightness enriched connected regions satisfy the following:

[0085] Average intensity of connected regions ;

[0086] Area of ​​connected regions ;

[0087] The threshold for cluster identification, and ; This is the threshold for ordinary effective coverage recognition; This is the minimum clustered connectivity area threshold.

[0088] 5. Batch Representative Value

[0089] When a batch contains n sample points, preferably, the arithmetic mean of the surface coating rates of each sample point is used as the batch surface coating rate, and the maximum value of the regional dispersion coefficient, exposed particle rate, and aggregation index of each sample point is used as the batch representative value, that is:

[0090]

[0091]

[0092]

[0093]

[0094] in: , , , These are the representative values ​​for each batch; , , , These are the detection results for the s-th sample point.

[0095] S7: Pass / Fail Judgment

[0096] The surface coating rate, regional dispersion coefficient, exposed particle rate, and agglomeration index are compared with preset quality control thresholds. The batch of mixture is deemed to have acceptable mixing uniformity when the following conditions are met; otherwise, it is deemed unacceptable.

[0097]

[0098]

[0099]

[0100]

[0101] in: The minimum surface coating rate threshold; preferred. It is 80%–90%; The threshold for the highest regional dispersion coefficient; preferred. It is 10%–15%; The threshold for the highest exposed particle rate; preferred. It is 5%–10%; The highest aggregation index threshold; preferred It is 8%–12%.

[0102] When the mixture to be tested fails to meet the requirements, adjust at least one of the following: mixing time, spraying method, spraying sequence, polymer dilution ratio, atomization intensity, or mixing equipment parameters, and retest.

[0103] In summary:

[0104] This invention introduces an identifiable tracer component to prepare a tracer polymer solution, which is then mixed with graded crushed stone, without significantly altering the film-forming and dispersion characteristics of the water-based polymer. Through multi-point sampling, near-single-layer single-particle sampling, and image acquisition under uniform optical conditions, the surface coating rate, regional dispersion coefficient, exposed particle rate, and agglomeration index are calculated after background correction, threshold segmentation, particle identification, and region statistics. These values ​​are compared with preset thresholds to achieve rapid quantitative determination of mixing uniformity and process feedback adjustment. This invention is applicable to indoor sample preparation, large-scale mixing production, and on-site quality control during construction.

[0105] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A rapid method for determining the mixing uniformity of water-based polymer-stabilized graded crushed stone, characterized in that: Includes the following steps: S1: Select water-based polymer and graded crushed stone, and add identifiable tracer components to the water-based polymer without significantly changing the film-forming and dispersion characteristics of the water-based polymer to prepare tracer polymer solution; S2: Spray or add the tracer polymer liquid to the graded crushed stone according to the preset polymer dosage and water content, and then mechanically mix to obtain the mixture to be tested. The water content is the optimal moisture content. S3: Extract multiple samples from different spatial locations of the mixture to be tested, and lay each sample flat on the observation carrier so that the particles are in a state of near-single-layer exposure. S4: Image acquisition of the sample under uniform optical conditions; S5: Perform background correction, tracer-sensitive channel extraction, particle projection region identification, threshold segmentation and noise removal on the acquired image to obtain the effective tracer coverage area, the high-brightness enrichment area and the analyzable particle projection area. S6: Divide the processed image into several statistical regions and calculate the surface coverage rate CR, regional dispersion coefficient CV, exposed particle rate UR, and aggregation index AI respectively. Among them, CR is the ratio of the effective tracer coverage area to the analyzable particle projection area, CV is the coefficient of variation of the local coverage rate of each statistical region, UR is the proportion of the number of particles with a coverage rate lower than the minimum effective coverage rate threshold to the total number of particles, and AI is the proportion of the area of ​​the bright enriched region to the total area of ​​the effective tracer coverage area. S7: Compare CR, CV, UR and AI with preset thresholds respectively. When CR is not lower than the preset lower limit and CV, UR and AI are not higher than their respective upper limits, the uniformity of the mixture to be tested is deemed to be qualified. Otherwise, it is deemed unqualified, and at least one of the following should be adjusted: mixing time, spraying method, spraying sequence, polymer dilution ratio or mixing equipment parameters, and then retested.

2. The method for rapid determination of the mixing uniformity of water-based polymer-stabilized graded crushed stone according to claim 1, characterized in that: The tracer group includes at least a fluorescent tracer, a visible light colorimetric agent, and a near-infrared responsive tracer; The amount of the tracer component added is 0.05% to 0.50% of the mass of the water-based polymer.

3. The method for rapid determination of the mixing uniformity of water-based polymer-stabilized graded crushed stone according to claim 1, characterized in that: The unified optical conditions include keeping the excitation light source wavelength, illumination angle, camera-sample distance, exposure parameters, and background plate reflectivity consistent.

4. The method for rapid determination of the mixing uniformity of water-based polymer-stabilized graded crushed stone according to claim 1, characterized in that: The plurality of sample points are no less than four, and are taken from different spatial locations of the mixture to be tested. The different spatial locations are representative spatial locations with different flow trajectories, and the different spatial locations include at least the surface layer, the middle layer, the bottom layer and the discharge port.

5. The method for rapid determination of the mixing uniformity of water-based polymer-stabilized graded crushed stone according to claim 1, characterized in that: The processed image is divided into 9 to 25 statistical regions of approximately equal area.

6. The method for rapid determination of the mixing uniformity of water-based polymer-stabilized graded crushed stone according to claim 1, characterized in that: The threshold segmentation includes at least the Otsu method, the adaptive threshold method, and the pre-calibrated fixed threshold method; The background correction employs one or more of the following: background image subtraction, flat field correction, top-hat transformation, or rolling ball background subtraction.

7. The method for rapid determination of the mixing uniformity of water-based polymer-stabilized graded crushed stone according to claim 1, characterized in that: The calculation of the exposed particle rate UR includes particle segmentation, which is accomplished through connected component analysis; When there is contact between particles, distance transformation and watershed algorithm are used for particle separation.

8. The method for rapid determination of the mixing uniformity of water-based polymer-stabilized graded crushed stone according to claim 1, characterized in that: The highlighted enriched regions are defined as those whose average intensity is not lower than the clustering recognition threshold. And the area of ​​the connected region is not less than the minimum clustered connected area threshold. The connected components, where , To effectively trace coverage and identify thresholds.

9. The method for rapid determination of the mixing uniformity of water-based polymer-stabilized graded crushed stone according to claim 1, characterized in that: The preset threshold must at least satisfy the following settings: The lower limit for surface coating rate is 80%–90%; the upper limit for regional dispersion coefficient is 10%–15%; the upper limit for exposed particle rate is 5%–10%; and the upper limit for aggregation index is 8%–12%.

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