A quantitative characterization method for the distribution of residual mortar layer on the surface of recycled aggregate in three dimensions

Abstract

This invention discloses a quantitative characterization method for the distribution of residual mortar layer on the surface of recycled aggregate in three dimensions, comprising: 1. immersing the recycled aggregate in a heavy metal ion solution; 2. fixing the immersed recycled aggregate in a plastic tube using a dispersion medium; 3. performing cross-sectional scanning of the recycled aggregate sample using an industrial CT system; 4. obtaining a grayscale threshold for distinguishing between natural particles and residual mortar based on digital image technology; 5. obtaining the actual spatial coordinates of the surface volume elements of the total recycled aggregate and its natural particles using a threshold segmentation method; 6. reconstructing the total recycled aggregate and its natural particles based on spherical harmonic functions, and calculating quantitative parameters such as the residual mortar encapsulation volume ratio and the residual mortar encapsulation surface area ratio based on this. This invention can accurately and conveniently quantify the residual mortar in recycled aggregate, achieving a precise description of the characteristics of recycled aggregate, thereby facilitating the rational and efficient application of recycled aggregate.

Description

Technical Field

[0001] This invention belongs to the field of recycled aggregate concrete, and specifically relates to a quantitative characterization method for the distribution of residual mortar layer on the surface of recycled aggregate in three dimensions. Background Technology

[0002] With the rapid urbanization in my country, the amount of construction waste is increasing year by year, and the proportion of recyclable components in construction waste is also constantly rising. Most construction waste is transported directly to the suburbs or urban peripheries for simple landfilling or open dumping without any treatment, which not only wastes land and resources but also pollutes the environment. On the other hand, the high demand for sand and gravel materials from the construction industry and infrastructure construction has led to resource depletion, landslides, and riverbed changes due to long-term sand and gravel mining, severely damaging the natural environment. The production and reuse of recycled aggregates is of great significance for conserving resources, protecting the environment, and achieving sustainable development in the construction industry.

[0003] Recycled aggregates prepared from waste concrete through simple crushing and screening processes often retain hardened cement paste on their surface. This results in recycled aggregates with high porosity, high water absorption, low bulk density, and high crushing value. Recycled concrete prepared using this type of aggregate exhibits multiple transition zones, significantly impacting its hardening strength, elastic modulus, impermeability, frost resistance, carbonation resistance, and chloride ion penetration resistance. Determining the content and distribution of the cement paste on the surface of recycled aggregates, and quantitatively describing their characteristics, is crucial and necessary for their application. Existing methods typically employ acid dissolution treatment, which can only measure the content of residual mortar but cannot determine the thickness of the mortar layer, the location of encapsulation, or other particle characteristics. Therefore, CN110823060A uses asphalt-coated recycled aggregate, utilizing the differences in nanomechanical parameters between residual mortar, recycled aggregate, and asphalt binder. An in-situ nanomechanical measurement system is used for hardness testing to determine the thickness of residual mortar at characteristic locations. However, this method requires high precision in sample preparation and grinding and can only achieve two-dimensional local thickness testing, failing to accurately characterize the features of residual mortar on the surface of actual recycled aggregate. To date, there is no quantitative evaluation method for the content and distribution of residual mortar on the surface of recycled aggregate at a three-dimensional level. Summary of the Invention

[0004] The present invention addresses the shortcomings of the prior art by proposing a quantitative characterization method for the distribution of residual mortar layer on the surface of recycled aggregate in three dimensions. This method aims to accurately and conveniently quantify the residual mortar in recycled aggregate, thereby achieving a precise description of the characteristics of recycled aggregate and facilitating its rational and efficient application.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] The present invention provides a quantitative characterization method for the distribution of residual mortar layer on the surface of recycled aggregate in three dimensions, characterized by comprising the following steps:

[0007] Step 1: After soaking the recycled aggregate in a heavy metal ion solution, recycled aggregate particles for CT scanning are obtained;

[0008] Step 2: The soaked recycled aggregate is dispersed and fixed in a circular plastic tube using a dispersion medium to obtain a recycled aggregate sample for CT scanning;

[0009] Step 3: Use an industrial CT system to perform cross-sectional scanning on the recycled aggregate sample to obtain a sequence of grayscale images of the sample's cross-section;

[0010] Step 4: Extract the grayscale sequence of a single recycled aggregate particle from the cross-sectional grayscale sequence of the sample, and use the maximum inter-class variance method to determine the optimal threshold for ternaryization of the grayscale sequence as the grayscale threshold for distinguishing between natural particles and residual mortar in a single recycled aggregate particle.

[0011] Step 5: Based on the grayscale threshold, the grayscale image sequence is processed using the threshold segmentation method to obtain the voxel set of a single recycled aggregate particle and the voxel set of natural particles in a single recycled aggregate particle, respectively.

[0012] A global three-dimensional Cartesian coordinate system is established with the lower left corner of each grayscale image in the grayscale image sequence as the origin of the two-dimensional Cartesian coordinate system, the two sides adjacent to the origin as the x-axis and y-axis respectively, and the thickness direction as the positive z-axis.

[0013] Identify the surface voxels of the corresponding voxel set, and obtain the actual spatial coordinates of the total recycled aggregate surface voxels in the global three-dimensional Cartesian coordinate system and the actual spatial coordinates of the natural particle surface voxels in the individual recycled aggregate particles according to the pixel position and pixel resolution of the surface voxels.

[0014] Step 6: Move the origin of the global three-dimensional Cartesian coordinate system to the geometric center of the natural particles in a single recycled aggregate particle to obtain a local three-dimensional Cartesian coordinate system;

[0015] Calculate the coordinate data of the surface volume element of a single recycled aggregate particle and the coordinate data of the surface volume element of the natural particle in the single recycled aggregate particle in the local three-dimensional Cartesian coordinate system, and convert them into coordinate data in the spherical coordinate system respectively; and the origin of the spherical coordinate system coincides with the origin of the local three-dimensional Cartesian coordinate system.

[0016] Based on the spherical harmonic function, the contours of a single recycled aggregate particle and the natural particles therein are reconstructed, and the residual slurry encapsulation volume ratio RV and residual slurry encapsulation surface area ratio RS are calculated using equations (1) and (2), respectively.

[0017]

[0018]

[0019] In equations (1) and (2), V RCA V is the volume of a single recycled aggregate particle. NA S represents the volume of natural particles in a single recycled aggregate particle; w-NA S is the surface area of ​​a single recycled aggregate particle where the natural particles are encapsulated by the residual slurry. t-NA This represents the total surface area of ​​the natural particles in a single recycled aggregate particle.

[0020] The quantitative characterization method described in this invention is also characterized in that, in step 6, equations (3) and (4) are used to perform spherical harmonic reconstruction on the contours of a single recycled aggregate particle and the natural particles therein, respectively:

[0021]

[0022]

[0023] In equations (3) and (4), N1 is the order of the spherical harmonic expansion; Let a be an nth-order m-th basis of spherical harmonics. nm and b nm The outlines of individual recycled aggregate particles and the natural aggregate particles therein correspond to... spherical harmonic coefficients; and Representing the surface volume elements of a single recycled aggregate particle and its natural particles at polar angle θ and azimuth angle respectively. The radius value at that time; and These are the reconstructed analytical expressions for the surface profiles of a single recycled aggregate particle and the natural particles within it, respectively.

[0024] In step 6, the volume V of a single recycled aggregate particle is calculated using equations (4) and (5) respectively. RCA and the volume V of the natural particles therein NA :

[0025]

[0026]

[0027] In step 6, the residual slurry coating surface area S w-NA and total surface area S t-NA It is obtained by following these steps:

[0028] Step a: Set the polar angle θ in [0, 2π] and the azimuth angle respectively. Divide the aggregate into N equal parts within the range [0,π], and obtain N on the surface of each individual recycled aggregate particle and the natural particles therein. 2 One surface point;

[0029] Step b: Use the Delaunay triangulation method to perform N-axis triangulation on the two contour surfaces mentioned above. 2 Triangulation of each surface point and drawing of triangular facets yields the approximate surface contours of the total recycled aggregate and its natural particles.

[0030] Step c: Compare at N respectively 2 From various angles and If there is a difference between the two values ​​at a certain angle, it means that the natural particles in a single recycled aggregate particle have residual slurry encapsulation at the corresponding angle; otherwise, it means that there is no residual slurry encapsulation.

[0031] Step d: Accumulate the area of ​​all triangular facets on the surface of the natural particles in a single recycled aggregate particle to obtain the total surface area S of the natural particles in the recycled aggregate. t-NA ;

[0032] Step e: Delete the triangular facets on the natural particles in a single recycled aggregate particle that are not covered by residual slurry, and sum the areas of the remaining triangular facets to obtain the surface area S of the natural particles in a single recycled aggregate particle that is covered by residual slurry. w-NA .

[0033] The present invention provides an electronic device, including a memory and a processor, wherein the memory is used to store a program that supports the processor in executing the quantization characterization method, and the processor is configured to execute the program stored in the memory.

[0034] The present invention provides a computer-readable storage medium on which a computer program is stored, wherein the computer program is executed by a processor to perform the steps of the quantization characterization method.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. This invention employs heavy metal ion immersion in recycled aggregate to amplify the density difference between residual slurry and natural aggregate. Then, industrial CT scanning and digital imaging techniques are used to extract the surface volume element spherical coordinate data of the recycled aggregate and its natural aggregate components. Furthermore, based on spherical harmonic basis functions, the surfaces of the recycled aggregate and its natural aggregate are reconstructed to obtain mathematical analytical expressions for each surface. Finally, numerical integration and triangular patch summation methods are used to accurately calculate parameters such as the residual slurry encapsulation volume ratio (RV) and residual slurry encapsulation surface area ratio (RS) in the recycled aggregate. These quantitative indicators can more accurately and comprehensively characterize the distribution of residual mortar on the surface of recycled aggregate, providing a basis for analyzing the influence of different crushing methods on the residual slurry stripping rate of recycled aggregate.

[0037] 2. Compared with existing methods that use nanomechanical technology to measure the local encapsulation thickness of residual mortar layers in two dimensions, this invention uses CT scanning, digital imaging, and spherical harmonic reconstruction to further identify and quantify the encapsulation of residual mortar in recycled aggregates in three dimensions, which helps to generate a geometric model of recycled aggregates in discrete element simulation of recycled aggregate concrete.

[0038] 3. Compared with the existing acid leaching method for measuring residual mortar content, this invention, through mathematical reconstruction of the surfaces of recycled aggregate and its natural aggregate, and by employing numerical integration and triangular patch summation methods, can further quantify and characterize the distribution characteristics of residual mortar in recycled aggregate, providing a basis for establishing the relationship between different encapsulation parameters of residual slurry and the performance of recycled aggregate concrete. Attached Figure Description

[0039] Figure 1 This is a flowchart of the quantitative characterization method of the present invention;

[0040] Figure 2 This is a three-dimensional view of a layer of recycled aggregate after industrial CT scanning according to the present invention;

[0041] Figure 3 This is a three-dimensional CT view of a single particle extracted according to the present invention;

[0042] Figure 4 This is a schematic diagram of the trialization result of the present invention using the Otsu's method;

[0043] Figure 5a This is a schematic diagram of the shape of the total recycled aggregate obtained by the threshold segmentation method of the present invention;

[0044] Figure 5b This is a schematic diagram showing the shape of natural particles in total recycled aggregate obtained by the threshold segmentation method of the present invention;

[0045] Figure 6a This is a schematic diagram showing the shape of the total recycled aggregate after spherical harmonic reconstruction according to the present invention;

[0046] Figure 6b This is a schematic diagram showing the shape of natural particles in the total recycled aggregate after spherical harmonic reconstruction according to the present invention;

[0047] Figure 7 This is a schematic diagram illustrating the calculation of surface area using the triangular facet summation method of the present invention. Detailed Implementation

[0048] In this embodiment, as Figure 1 As shown, a quantitative characterization method for the distribution of residual mortar layer on the surface of recycled aggregate in three dimensions includes the following steps:

[0049] Step 1: Since the water absorption rate of residual mortar is much greater than that of natural aggregate, the recycled aggregate is soaked in a heavy metal ion solution such as CsCl to amplify the density difference between residual mortar and natural aggregate in the recycled aggregate, thus obtaining recycled aggregate particles for CT scanning; the mass fraction of the CsCl heavy metal ion solution used is generally not less than 30%.

[0050] Step 2: To prevent the recycled aggregate particles from coming into contact with each other and from shaking during the scanning process, the soaked recycled aggregate is dispersed and fixed in a circular plastic tube using a dispersion medium such as silica gel to obtain a recycled aggregate sample for CT scanning. The reason for using a low-density matrix such as silica gel is to facilitate the extraction of the recycled aggregate phase using the threshold segmentation method later.

[0051] Step 3: Use an industrial CT system to perform cross-sectional scanning on the recycled aggregate sample to obtain a sequence of grayscale images of the sample's cross-section, such as... Figure 2 As shown; in order to accurately identify the residual slurry coating on the surface of recycled aggregate, it is necessary to control the sample size or scanning parameters to ensure that the pixel resolution is no greater than 30-40 μm;

[0052] Step 4: Extract the grayscale sequence of individual recycled aggregate particles from the cross-sectional grayscale sequence of the sample (e.g., ...). Figure 3 As shown, the optimal threshold for ternaryization of the grayscale image sequence is determined using the Otsu's method (maximum inter-class variance method), which serves as the grayscale threshold for distinguishing between natural particles and residual mortar in a single recycled aggregate particle. Figure 4 The results of ternary modeling of a cross-section of a certain recycled particle based on Otsu are shown.

[0053] Step 5: Obtain the spatial coordinates of a single recycled aggregate particle and the surface volume elements of its natural particles based on the threshold segmentation method:

[0054] Step 5-1: Based on the grayscale threshold, the grayscale image sequence is processed using a threshold segmentation method to obtain the voxel set of a single recycled aggregate particle and the voxel set of natural particles within a single recycled aggregate particle, such as... Figure 5a and Figure 5b As shown;

[0055] Step 5-2: Establish a global three-dimensional Cartesian coordinate system with the lower left corner of each grayscale image in the grayscale image sequence as the origin of the two-dimensional Cartesian coordinate system, the two sides adjacent to the origin as the x-axis and y-axis respectively, and the thickness direction as the positive z-axis.

[0056] Step 5-3: Use the built-in function bwperim in Matlab to identify the surface voxels of the corresponding voxel set, and obtain the actual spatial coordinates of the total recycled aggregate surface voxels and the actual spatial coordinates of the natural particle surface voxels in a single recycled aggregate particle in the global three-dimensional Cartesian coordinate system according to the pixel position and pixel resolution of the surface voxels.

[0057] Step 6: Perform spherical harmonic reconstruction of the surface volume element coordinates of individual recycled aggregate particles and their natural particles, and quantify the distribution parameters of the residual mortar layer:

[0058] Step 6-1: To facilitate the conversion of coordinate data to the spherical coordinate system, the origin of the global three-dimensional Cartesian coordinate system is first moved to the geometric center of the natural particles in a single recycled aggregate particle to obtain the local three-dimensional Cartesian coordinate system.

[0059] Step 6-2: Calculate the coordinate data of the surface volume element of a single recycled aggregate particle and the coordinate data of the surface volume element of a single recycled aggregate particle in the local three-dimensional Cartesian coordinate system, and convert the data in the local coordinate system to the spherical coordinate system according to Equation (1); and the origin of the spherical coordinate system coincides with the origin of the local three-dimensional Cartesian coordinate system.

[0060]

[0061] In equation (1), θ is the angle between the directed line segment from the particle center to each surface element and the positive x-axis, i.e., the polar angle; when viewed from the positive z-axis, counterclockwise is positive. The azimuth angle is the angle between the directed line segment from the particle center to each surface volume element and the positive z-axis. The polar angle is the distance from the particle surface volume element to its center of mass, i.e., the radius. x, y, and z are the coordinates of the particle surface volume element in the local three-dimensional Cartesian coordinate system, respectively.

[0062] Step 6-3: According to equations (2) and (3), the contours of individual recycled aggregate particles and their natural particles are reconstructed based on spherical harmonic functions. The reconstructed contour shape is as follows: Figure 6a and Figure 6b As shown;

[0063]

[0064]

[0065] In equations (2) and (3), N1 is the order of the spherical harmonic expansion, which should be no less than 15 to ensure reconstruction accuracy; Let a be an nth-order m-th basis of spherical harmonics. nm and b nm These are the total recycled aggregate and the natural aggregate profiles corresponding to... The spherical harmonic coefficients can be calculated using the Gaussian integration method, where the number of Gaussian integration points at both the polar angle and the azimuth angle should be no less than 120 to ensure the accuracy of the integration. and Representing the total recycled aggregate and the volumetric elements on the surface of its natural particles at polar angle θ and azimuth angle respectively. The radius value at that time; and These are the analytical expressions for the reconstruction of the total recycled aggregate and the surface of the natural particles therein, respectively.

[0066] Step 6-4: Calculate the total volume V of recycled aggregate using equations (4) and (5) respectively. RCA and the volume V of the natural particles therein NA :

[0067]

[0068]

[0069] Step 6-5: Calculate the total surface area S of natural particles in a single recycled aggregate. t-NA and the surface area S of the residual slurry w-NA First, set the polar angle θ in [0, 2π] and the azimuth angle respectively. The area is divided into N equal parts within the range [0,π]. To ensure the accuracy of the surface area calculation using the triangular patch summation method, the number of equal parts N for both the polar angle and the azimuth angle should not be less than 256. N equal parts are obtained on the surface of each individual recycled aggregate particle and the natural particles within it. 2 One surface point;

[0070] The Delaunay triangulation method was used to analyze the N values ​​of the two contour surfaces mentioned above. 2 Triangulation of each surface point and drawing of triangular facets yields the approximate surface contours of the total recycled aggregate and its natural particles.

[0071] Compare at N respectively 2 From various angles and To account for the impact of reconstruction accuracy, a truncation error can be set. If the difference between the two at a certain angle is greater than this stage error, it means that the natural particles in a single recycled aggregate particle at the corresponding angle have residual slurry encapsulation; otherwise, it means that there is no residual slurry encapsulation.

[0072] The total surface area S of the natural particles in the recycled aggregate is obtained by calculating the area of ​​all triangular facets on the surface of each natural particle in a single recycled aggregate particle. t-NA ;

[0073] Remove the triangular facets on the natural particles of a single recycled aggregate particle that are not covered by residual slurry, and sum the areas of the remaining triangular facets to obtain the surface area S of the natural particles in a single recycled aggregate particle that are covered by residual slurry. w-NA The calculation principle for the area of ​​each triangular facet is as follows: Figure 7 As shown in equation (6).

[0074]

[0075] In equation (6), S i p is the area of ​​the i-th triangular facet; i1 ,p i2 and p i3 θ represents the three vertices of the i-th triangular facet; i Represents the vector in the i-th triangular facet and The included angle.

[0076] Step 6-6: Calculate the residual slurry encapsulation volume ratio RV and the residual slurry encapsulation surface area ratio RS using equations (7) and (8), respectively;

[0077]

[0078]

[0079] In equations (7) and (8), V RCA V is the total volume of recycled aggregate. NA S represents the volume of natural aggregate in the recycled aggregate; w-NA S represents the surface area of ​​natural particles in recycled aggregate that are encapsulated by residual slurry. t-NA This represents the total surface area of ​​natural particles in the recycled aggregate.

[0080] Step 7: Separate the recycled aggregate particles from the silica gel and other dispersion matrix, dry them, and crush them using a mortar. Since some of the calcium aggregate will also be dissolved by hydrochloric acid, a salicylic acid methanol solution is used to dissolve the residual slurry in the recycled aggregate. The volume change of the recycled aggregate before and after acid dissolution is measured using a graduated cylinder to obtain the residual slurry encapsulation volume ratio RV of the recycled aggregate, so as to verify the accuracy of the residual slurry encapsulation volume ratio RV calculated based on CT scanning technology and spherical harmonic function.

[0081] Example: The following steps were used to measure and calculate the characteristic parameters of residual mortar made from recycled aggregate:

[0082] Step 1: Soaking recycled aggregate with heavy metal ions:

[0083] Dissolve 15g of CsCl powder in 35g of water to prepare a 30% CsCl solution. Place recycled fine aggregate with a particle size in the range of 2.36-4.75mm into the solution and soak for 12h.

[0084] Step 2: Dispersing and fixing recycled aggregates in a silica matrix:

[0085] Pour addition-cured silicone into a plastic tube with an inner diameter of 30 mm in layers. When the cured silicone reaches a strength that can support the recycled particles without settling, place the recycled aggregates dispersedly in the silicone matrix, ensuring that the particles do not come into contact with each other. Finally, continue to pour silicone to cover the particles.

[0086] Step 3: Industrial CT cross-sectional scanning of the sample:

[0087] After the silicone has cured, the plastic tube containing the recycled aggregate was subjected to CT tomography. The obtained image resolution was 1980×1980×253, and the interlayer spacing of the planar and axial scan slices was 0.0197mm.

[0088] Step 4: Extract individual particles and determine the grayscale threshold that distinguishes between slurry and particles:

[0089] Extract the grayscale image sequence of a single particle, such as Figure 3 As shown, the optimal threshold for ternary gradation was determined to be 68 using the maximum inter-class variance method, which serves as the grayscale threshold for distinguishing between natural particles and residual mortar.

[0090] Step 5: Obtain the surface volume coordinates of total recycled aggregate particles and their natural particles:

[0091] By setting different thresholds, voxel sets of total recycled aggregate and its natural particles are obtained respectively. The scanned volume of the particles is obtained by multiplying the number of voxels of each set by the cube of the image pixel size. RCA and V NA The thicknesses are 40.69 and 36.56 mm respectively. 3 The pixel coordinates of the surface volume elements of the total recycled aggregate and its natural particles can be obtained by using the built-in function bwperim in Matlab. Multiplying these by the image resolution will give the actual spatial coordinates.

[0092] Step 6: Contour reconstruction and parameter calculation based on spherical harmonic basis functions:

[0093] The origin of the three-dimensional Cartesian coordinate system is translated to the center of the natural particle region in a single recycled aggregate, and the translated surface volume element coordinates are transformed to the spherical coordinate system. Then, the single recycled aggregate and its natural particles are reconstructed using spherical harmonics according to equations (2) and (3), where a 15th-order spherical harmonic function is used for reconstruction.

[0094] Based on the mathematical analytical expression of the surface profile after spherical harmonic reconstruction, the total recycled aggregate V is calculated according to equations (4) and (5). RCA and the volume V of the natural particles therein NA They are 39.85mm respectively. 3 and 36.98mm 3 The results show good agreement with the voxel stacking method of CT results.

[0095] Divide the polar angle and azimuth angle into 256 equal parts, and draw triangular facets for each surface based on the Delaunay triangulation method. The total surface area S can be obtained by summing the areas of the triangular facets of the natural particles in the recycled aggregate. t-NA It is 68.23mm 2 .

[0096] Traverse N 2 At each angle, with a cutoff error set to 0.005mm, the results were compared. and The difference is used to determine whether there is encapsulation at this angle; the triangular facets on the natural particles in the recycled aggregate that are not encapsulated by the residual slurry are deleted, and the sum of the areas of the remaining triangular facets is calculated to obtain the surface area S of the natural particles in the recycled aggregate that is encapsulated by the residual slurry. w-NA It is 15.32mm 2 ;

[0097] Further calculation using formula (7) yielded a residual slurry-coated volume ratio RV of 7.76%; calculation using formula (8) yielded a residual slurry-coated surface area ratio RS of 22.06%.

[0098] Step 7: Verify the calculation results based on the acid dissolution method:

[0099] The recycled aggregate particles obtained from CT scans were separated from the silica matrix. The extracted recycled aggregate was then selected, and its volume was measured using a high-precision graduated cylinder with a range of 0.2 ml (measuring accuracy up to 0.003 ml) based on the displacement method. The result was 39 mm². 3 The recycled particles were then crushed in a mortar. 14g of salicylic acid was dissolved in 80ml of anhydrous methanol to prepare a salicylic acid-methanol solution. The crushed recycled particles were then poured into this solution to dissolve the residual slurry in the recycled aggregate. After dissolving for 2 hours, the mixture was filtered, and the remaining volume was measured; the result was 36mm. 3The residual slurry volume ratio (RV) of the recycled aggregate was calculated to be 7.69% based on the volume change before and after dissolution. This is similar to the RV calculated based on CT and spherical harmonic reconstruction methods, which verifies the accuracy of the residual slurry encapsulation volume ratio (RV) calculated based on CT technology and spherical harmonic functions.

[0100] In this embodiment, an electronic device includes a memory and a processor. The memory stores a program that supports the processor in executing the above-described method, and the processor is configured to execute the program stored in the memory.

[0101] In this embodiment, a computer-readable storage medium stores a computer program, which is executed by a processor to perform the steps of the above method.

Claims

1. A method of quantitatively characterizing the distribution of surface residual mortar layer of recycled aggregates of three-dimensional layers, characterized in that, The method comprises the following steps: Step 1: soaking the recycled aggregate after regeneration with a heavy metal ion solution to obtain recycled aggregate particles for CT scanning; Step 2: dispersing the soaked recycled aggregate in a dispersion medium and fixing it in a circular plastic tube to obtain a recycled aggregate sample for CT scanning; Step 3: using an industrial CT system to scan the cross section of the recycled aggregate sample to obtain a sequence of cross-sectional grayscale images of the sample; Step 4: extracting a grayscale image sequence of an individual recycled aggregate particle from the sequence of cross-sectional grayscale images of the sample, and using the maximum inter-class variance method to determine the optimal threshold value of the grayscale image sequence for three-value conversion as the grayscale threshold value for distinguishing between natural particles and residual mortar in the individual recycled aggregate particle; Step 5: based on the grayscale threshold value, using threshold segmentation to process the grayscale image sequence to obtain a voxel set of the individual recycled aggregate particle and a voxel set of the natural particles in the individual recycled aggregate particle; Taking the lower left corner of each grayscale image in the grayscale image sequence as the origin of a two-dimensional Cartesian coordinate system, taking the two edges adjacent to the origin as the x-axis and y-axis, and taking the thickness direction as the positive direction of the z-axis, a global three-dimensional Cartesian coordinate system is established; Identifying the surface voxels corresponding to the voxel set, and obtaining the actual spatial coordinates of the total recycled aggregate surface voxels and the actual spatial coordinates of the natural particle surface voxels in the individual recycled aggregate particle in the global three-dimensional Cartesian coordinate system based on the pixel position and pixel resolution of the surface voxels; Step 6: moving the origin of the global three-dimensional Cartesian coordinate system to the geometric center position of the natural particles in the individual recycled aggregate particle to obtain a local three-dimensional Cartesian coordinate system; Calculating the coordinate data of the individual recycled aggregate particle surface voxels and the coordinate data of the natural particle surface voxels in the individual recycled aggregate particle in the local three-dimensional Cartesian coordinate system, and converting them into coordinate data in a spherical coordinate system; and the origin of the spherical coordinate system coincides with the origin of the local three-dimensional Cartesian coordinate system; Based on spherical harmonics, the profiles of the individual recycled aggregate particle and the natural particles therein are reconstructed, and the residual mortar wrapping volume ratio RV and the residual mortar wrapping surface area ratio RS are calculated using formulas (1) and (2), respectively; In formula (1) and formula (2), V RCA is the volume of the individual recycled aggregate particle, V NA is the volume of the natural particle in the individual recycled aggregate particle; S w-NA is the surface area of the natural particle in the individual recycled aggregate particle that is wrapped by residual paste, S t-NA is the total surface area of the natural particle in the individual recycled aggregate particle.

2. The method of claim 1, wherein, In step 6, spherical harmonic reconstruction is performed on the profiles of the individual recycled aggregate particle and the natural particles therein using formulas (3) and (4), respectively: In formula (3) and formula (4), N1 is a spherical harmonic expansion order number; is an n-th order m-th basis of spherical harmonics, a nm and b nm are respectively a single recycled aggregate particle and a profile of a natural aggregate in which a spherical harmonic coefficient of and respectively represent a single recycled aggregate particle and a radius value of a surface voxel of a natural particle at a polar angle of θ and an azimuthal angle of ; and are respectively a single recycled aggregate particle and a reconstructed analytical expression of a natural particle surface profile.

3. The method of claim 2, wherein, The step 6 is to calculate the volume V of individual recycled aggregate particles using the formula (4) and (5) respectively RCA and wherein the volume V of natural particles NA :

4. The method of claim 2, wherein, S is the surface area of the residual slurry in step 6 w-NA and the total surface area S t-NA is obtained as follows: Step a: The polar angle θ is equally divided into N parts in the range [0, 2π] and the azimuthal angle φ is equally divided into N parts in the range [0, π] In the range [0, π] into N parts, N 2 surface points are obtained on the surface of a single recycled aggregate particle and the natural particles therein Step b: Delaunay triangulation is used to triangulate the N 2 surface points of the two profile surfaces respectively, and the approximate surface profiles of the total recycled aggregate and the natural particles therein are obtained after drawing the triangular facets. Step c: Compare at N respectively 2 From various angles and If there is a difference between the two values ​​at a certain angle, it means that the natural particles in a single recycled aggregate particle have residual slurry encapsulation at the corresponding angle; otherwise, it means that there is no residual slurry encapsulation. Step d: the area of all triangular facets of the natural particle surface in a single recycled aggregate particle is cumulatively calculated, thereby obtaining the total surface area S of the natural particles in the recycled aggregate t-NA ; Step e: deleting the triangular facets on the natural particle in the single recycled aggregate particle that are not wrapped by the residual paste, and cumulatively calculating the sum of the areas of the remaining triangular facets, thereby obtaining the surface area S of the natural particle wrapped by the residual paste in the single recycled aggregate particle w-NA .

5. An electronic device comprising a memory and a processor, characterized in that The memory is used to store a program supporting the processor to execute the quantification characterization method of any one of claims 1-4, and the processor is configured to execute the program stored in the memory.

6. A computer-readable storage medium having stored thereon a computer program, characterized in that The computer program is executed by the processor to perform the steps of the quantification characterization method of any one of claims 1-4.

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