A numerical simulation method for the performance of recycled concrete

Abstract

This invention relates to the field of recycled concrete technology and discloses a numerical simulation method for the performance of recycled concrete. The method includes: generating a geometrical distribution framework of recycled aggregate by combining aggregate gradation, old mortar adhesion rate, and average thickness of the old ITZ (intermediate temperature zone) to construct a polygonal microstructure of the recycled concrete; calculating the stress distribution values ​​of the polygonal microstructure and locating the stress concentration areas and ITZ regions; setting a damage initiation location locator for the polygonal microstructure using initial damage points to track the initial propagation path's trajectory within the polygonal microstructure; setting the five-phase constitutive relationship of the polygonal microstructure and, in conjunction with external loads, measuring the damage variables of the polygonal microstructure to generate a damage cloud map; and performing numerical simulation processing of the recycled concrete performance by combining the damage cloud map, propagation trajectory, damage initiation location locator, and polygonal microstructure. This invention can improve the accuracy of recycled concrete performance simulation.

Description

Technical Field

[0001] This invention relates to a numerical simulation method for the performance of recycled concrete, belonging to the field of recycled concrete technology. Background Technology

[0002] Recycled concrete refers to a new type of concrete material formed by processing waste concrete components through crushing, washing, and screening to produce recycled aggregates of different particle sizes, which partially or completely replace natural aggregates (such as sand and gravel) in a certain proportion, and then mixing them with cement, water, and other materials. The use of recycled concrete can reduce dependence on natural sand and gravel and alleviate resource shortage pressure. However, although recycled concrete can reduce the consumption of natural aggregates, its mechanical properties, durability, and other indicators differ significantly from ordinary concrete due to differences in the source of waste concrete and the presence of hardened cement paste on the surface of recycled aggregates. These differences not only affect the application scope of recycled concrete in actual engineering projects but may also have potential impacts on the safety and service life of structures. Therefore, a comprehensive evaluation of the performance of recycled concrete is particularly important.

[0003] Traditional numerical simulation of recycled concrete performance mainly utilizes classical numerical calculation methods, such as the finite element method, which is based on the theory of micromechanics of materials. It simulates macroscopic properties by constructing a multiphase model of the material. Although this method can qualitatively reveal the micromechanical mechanism of the mechanical behavior of recycled concrete, it cannot characterize the performance response of recycled concrete under complex stress states, which limits the accuracy and reliability of the simulation results.

[0004] Therefore, a solution is urgently needed to improve the accuracy of performance simulation of recycled concrete. Summary of the Invention

[0005] This invention provides a numerical simulation method for the performance of recycled concrete, the main purpose of which is to improve the accuracy of the performance simulation of recycled concrete.

[0006] To achieve the above objectives, the present invention provides a numerical simulation method for the performance of recycled concrete, comprising:

[0007] Obtain recycled concrete and extract recycled aggregate from the recycled concrete. Measure the old mortar adhesion rate, average thickness of the old ITZ, and aggregate gradation of the recycled aggregate. Combine the aggregate gradation, the old mortar adhesion rate, and the average thickness of the old ITZ to generate a geometric distribution framework for the recycled aggregate.

[0008] Based on the geometric distribution framework, a polygonal microstructure of the recycled concrete is constructed, the stress distribution value of the polygonal microstructure is calculated, the stress concentration area of ​​the polygonal microstructure is located using the stress distribution value, and the ITZ region of the polygonal microstructure is identified based on the average thickness of the old ITZ.

[0009] The initial damage point of the polygonal microstructure is identified from the stress concentration area and the ITZ region. The damage initiation position determiner of the polygonal microstructure is set using the initial damage point. The initial expansion path of the initial damage point is identified. Based on the initial damage point, the expansion trajectory of the initial expansion path in the polygonal microstructure is tracked.

[0010] Based on the old mortar adhesion rate and the average thickness of the old ITZ, the five-phase constitutive relationship of the polygonal microstructure is set. An external load is applied to the polygonal microstructure, and the damage variable of the polygonal microstructure under the external load is determined by combining the external load and the five-phase constitutive relationship.

[0011] Based on the damage variables, a damage cloud map of the polygonal microstructure is generated. Combining the damage cloud map, the expansion trajectory, the damage initiation location determiner, and the polygonal microstructure, the performance numerical simulation of the recycled concrete is performed to obtain the performance numerical simulation results.

[0012] Optionally, the step of generating the geometric distribution framework of the recycled aggregate by combining the aggregate gradation, the old mortar adhesion rate, and the average thickness of the old ITZ includes:

[0013] Based on the aggregate gradation, the multi-size spatial layout of the recycled aggregate is identified to construct the initial three-dimensional framework of the recycled aggregate.

[0014] Based on the old mortar adhesion rate, an old mortar coating layer is generated on the aggregate surface of the initial three-dimensional frame to obtain an aggregate-mortar composite frame.

[0015] Based on the average ITZ thickness, an interface transition layer is created at the aggregate-old mortar contact interface of the aggregate-mortar composite frame to generate the target three-dimensional frame.

[0016] The CT scan data and performance data of the recycled aggregate are collected, and the target three-dimensional frame is corrected using the CT scan data and performance data to generate the geometric distribution frame of the recycled aggregate.

[0017] Optionally, constructing the polygonal mesostructure of the recycled concrete based on the geometric distribution framework includes:

[0018] Extract the recycled aggregate and its geometric phase label corresponding to the geometric distribution framework;

[0019] The aggregate surface, ITZ layer, and old mortar layer of the recycled aggregate are separated from the geometric distribution framework.

[0020] The aggregate surface, the ITZ layer, and the old mortar layer are subjected to triangular meshing to obtain a surface triangular mesh.

[0021] The surface triangular mesh is converted into a tetrahedral volume mesh, and the tetrahedral volume mesh is subjected to material property mapping based on the geometric phase label to obtain the mesostructure.

[0022] Acquire microstructural images of the recycled concrete and extract the aggregate-mortar-ITZ distribution characteristics from the microstructural images;

[0023] Construct a spatial mapping relationship between the aggregate-mortar-ITZ distribution characteristics and the microstructure;

[0024] Based on the spatial mapping relationship, the positions of the mesh nodes in the microstructure are optimized to obtain the polygonal microstructure.

[0025] Optionally, identifying the ITZ region of the polygonal mesostructure based on the average thickness of the old ITZ includes:

[0026] Retrieve the recycled concrete corresponding to the polygonal microstructure;

[0027] The internal three-dimensional structure of the recycled concrete was obtained, and the mechanical properties of the recycled concrete were measured. Simultaneously, microscopic morphological images of the recycled concrete were acquired.

[0028] Based on the microscopic morphology image, the aggregate-mortar interface of the recycled concrete is identified, and the gray-level co-occurrence matrix of the aggregate-mortar interface is calculated.

[0029] Based on the gray-level co-occurrence matrix, the interface texture features of the recycled concrete are extracted;

[0030] The density distribution characteristics of the recycled concrete are extracted from the internal three-dimensional structure, and the modulus gradient characteristics of the recycled concrete are identified based on the mechanical properties.

[0031] By combining the average thickness of the old ITZ, the interface texture features, the density distribution features, and the modulus gradient features, the ITZ region of the polygonal microstructure is identified.

[0032] Optionally, identifying the initial damage points of the polygonal mesostructure from the stress concentration region and the ITZ region includes:

[0033] Calculate the normalized stress gradient between adjacent elements within the stress concentration region;

[0034] The degree of degradation in the ITZ region is quantified to obtain the ITZ degradation degree;

[0035] Calculate the percentage of microcracks per unit area within the ITZ region;

[0036] Based on the normalized stress gradient, the ITZ degradation degree, and the proportion of microcracks, a damage accumulation index for the polygonal mesostructure is constructed.

[0037] Set a damage threshold for the damage accumulation index, and use the damage threshold to determine the potential damage initiation region of the polygonal mesostructure;

[0038] Damage initiation seed points of the polygonal mesostructure are identified from the potential damage initiation region;

[0039] Abnormal points are identified from the damage initiation seed points, and the abnormal points are removed to obtain the initial damage points of the polygonal microstructure.

[0040] Optionally, the step of using the initial damage point to set the damage initiation location determiner of the polygonal mesostructure includes:

[0041] Extract the new ITZ region and the old ITZ region corresponding to the polygonal mesoscopic architecture;

[0042] Based on the initial damage point, identify the local stress field and microcrack layout corresponding to the new ITZ region and the old ITZ region;

[0043] Identify the initial damage point coordinate set corresponding to the initial damage point to construct the damage point spacing matrix of the polygonal mesostructure;

[0044] The stress concentration degree corresponding to the new ITZ region and the old ITZ region was measured respectively, and the performance degradation rate corresponding to the new ITZ region and the old ITZ region was analyzed based on the microcrack layout.

[0045] Based on the damage point spacing matrix, the stress concentration degree, and the performance degradation rate, the damage feature vector of the polygonal mesostructure is extracted.

[0046] Based on the damage feature vector, a damage determination rule for the polygonal mesoscopic architecture is constructed.

[0047] Based on the damage determination rule, an adaptive threshold is set for the polygonal mesostructure;

[0048] Based on the adaptive threshold and the initial set of damage point coordinates, a damage propagation network for the polygonal mesoscopic architecture is generated.

[0049] Based on the damage transmission network, a dual-mode damage verification mechanism is set for the polygonal mesoscopic architecture;

[0050] Based on the damage transmission network and the dual-mode damage verification mechanism, a damage initiation location determiner for the polygonal mesoscopic architecture is set.

[0051] Optionally, the step of tracing the expansion trajectory of the initial expansion path in the polygonal mesostructure based on the initial damage point includes:

[0052] Based on the initial damage point, mark the new-old ITZ stress concentration areas of the polygonal mesostructure;

[0053] Construct a dual-channel analysis unit for the initial extension path in the new-old ITZ stress concentration zone, and configure the real-time tracking node of the dual-channel analysis unit;

[0054] Based on the dual-channel analysis unit and the real-time tracking node, the trajectory topology network of the polygonal mesoscopic architecture is set;

[0055] Based on the trajectory topology network, a damage evolution monitor with the polygonal mesoscopic architecture is configured;

[0056] The damage evolution monitor is used to track the expansion trajectory of the initial expansion path in the polygonal microstructure.

[0057] Optionally, setting the five-phase constitutive relationship of the polygonal microstructure based on the old mortar adhesion rate and the average thickness of the old ITZ includes:

[0058] Based on the old mortar adhesion rate and the average thickness of the old ITZ, the material phase boundaries of the polygonal microstructure are identified.

[0059] Based on the material phase boundaries, the five-phase material of the polygonal mesostructure is determined;

[0060] Construct the stiffness transfer matrix of the five-phase material;

[0061] Based on the stiffness transfer matrix, the stress distribution weights of the polygonal mesostructure are set;

[0062] Configure the multi-scale constitutive units of the polygonal mesoscopic architecture according to the stress allocation weights;

[0063] The five-phase constitutive relation of the polygonal mesoscopic architecture is set through the multi-scale constitutive unit.

[0064] Optionally, generating the damage cloud map of the polygonal mesoscopic architecture based on the damage variables includes:

[0065] Based on the damage variables, a damage level threshold is set for the polygonal mesostructure;

[0066] Based on the damage level threshold, identify the damage level regions of the polygonal mesostructure;

[0067] Construct geometric mapping units corresponding to the damage level region;

[0068] Based on the geometric mapping unit, the graphics generation rules for the polygonal microstructure are set;

[0069] Configure the dynamic visualization engine for the polygonal microstructure based on the graphics generation rules;

[0070] Based on the dynamic visualization engine, a damage cloud map of the polygonal microstructure is generated.

[0071] Optionally, the performance numerical simulation of the recycled concrete is performed by combining the damage cloud map, the expansion trajectory, the damage initiation location determiner, and the polygonal microstructure to obtain performance numerical simulation results, including:

[0072] Based on the aforementioned polygonal microstructure, the multi-scale material composition elements of the recycled concrete were analyzed.

[0073] The mechanical properties of the constituent elements of the multi-scale material were analyzed;

[0074] Based on the multi-scale material composition elements and the mechanical properties, the damage evolution characteristic parameters of the recycled concrete are set;

[0075] The initial damage core area of ​​the recycled concrete is located using the damage initiation location determiner.

[0076] Based on the aforementioned expansion trajectory, a multi-crack collaborative expansion network for the recycled concrete is constructed.

[0077] Based on the damage cloud map, a damage distribution characterization system for the recycled concrete is created;

[0078] By combining the damage evolution characteristic parameters, the initial damage core region, the multi-crack collaborative propagation network, and the damage distribution characterization system, a full-cycle performance evolution map of the recycled concrete is generated.

[0079] Based on the full-cycle performance evolution map, the performance numerical simulation of the recycled concrete is performed to obtain the performance numerical simulation results.

[0080] Compared to the problems described in the background art, the embodiments of the present invention, by measuring the old mortar adhesion rate, average thickness of the old ITZ, and aggregate gradation of the recycled aggregate, can optimize the mix design, pretreatment methods, and numerical simulation of recycled concrete, thereby improving the performance of recycled concrete. Furthermore, by combining the aggregate gradation, the old mortar adhesion rate, and the average thickness of the old ITZ to generate a geometric distribution framework of the recycled aggregate, the embodiments of the present invention can more accurately simulate the mechanical behavior of recycled concrete. By constructing a polygonal microstructure of the recycled concrete based on the geometric distribution framework, the embodiments of the present invention can realistically and comprehensively present the structural characteristics of recycled concrete at the microscale, making the numerical simulation more closely resemble the actual material and improving the accuracy and reliability of the simulation results. Furthermore, by using the stress distribution values ​​to locate the stress concentration areas of the polygonal microstructure and identifying the ITZ regions of the polygonal microstructure based on the average thickness of the old ITZ, the embodiments of the present invention help to deeply understand the failure mechanism of recycled concrete, thereby more accurately simulating the stress transmission path and the expansion path of damage from the starting point. This invention provides a key basis for improving material performance. In this embodiment, by using the initial damage point to set the damage initiation location determiner of the polygonal microstructure, the accurate initial damage location and damage mode can be provided for numerical simulation, thereby improving the accuracy of the simulation. Furthermore, by tracking the expansion trajectory of the initial expansion path in the polygonal microstructure based on the initial damage point, this invention can improve the reliability assessment efficiency of the polygonal microstructure of recycled concrete and achieve early warning of damage expansion risk. In this embodiment, by setting the five-phase constitutive relationship of the polygonal microstructure according to the old mortar adhesion rate and the average thickness of the old ITZ, multi-scale damage mapping of recycled concrete can be achieved, improving the accuracy of recycled concrete performance prediction and guiding the optimized design of recycled aggregates. Furthermore, by applying external loads to the polygonal microstructure and combining the external loads and the five-phase constitutive relationship, the damage variables of the polygonal microstructure under the external loads are measured, which helps to understand the behavior of materials under different load conditions, thereby enabling accurate simulation of material response.This invention, through generating a damage cloud map of the polygonal mesostructure based on the damage variables, can effectively reveal the internal failure mechanism of the material, providing an intuitive basis for numerical simulation of recycled concrete performance. Finally, by combining the damage cloud map, the expansion trajectory, the damage initiation location determiner, and the polygonal mesostructure, this invention performs numerical simulation of the recycled concrete performance, obtaining performance simulation results. This allows for more accurate simulation of the stress distribution and damage evolution process of recycled concrete in practical applications, significantly improving the prediction accuracy of recycled concrete performance, reducing reliance on actual experiments, thereby improving R&D efficiency and reducing costs. Simultaneously, it can optimize the microstructure design of recycled concrete, improving the material's mechanical properties and durability. Therefore, the numerical simulation method for recycled concrete performance provided by this invention can improve the accuracy of recycled concrete performance simulation. Attached Figure Description

[0081] Figure 1 This is a flowchart illustrating a numerical simulation method for the performance of recycled concrete according to an embodiment of the present invention.

[0082] Figure 2 This is a schematic diagram of the microstructure of recycled concrete used to implement the numerical simulation method for the performance of recycled concrete according to an embodiment of the present invention.

[0083] Figure 3 This is a schematic diagram of the geometric distribution framework of recycled aggregates for implementing the numerical simulation method for the performance of recycled concrete according to an embodiment of the present invention;

[0084] Figure 4 This is a functional block diagram of the numerical simulation system for the performance of recycled concrete provided in an embodiment of the present invention.

[0085] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0086] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0087] This application provides a method for numerically simulating the performance of recycled concrete. The execution subject of this method includes, but is not limited to, at least one of the following electronic devices that can be configured to execute the method provided in this application: a server, a terminal, etc. In other words, the method for numerically simulating the performance of recycled concrete can be executed by software or hardware installed on a terminal device or a server device. The server includes, but is not limited to, a single server, a server cluster, a cloud server, or a cloud server cluster.

[0088] Example 1:

[0089] Reference Figure 1 The diagram shown is a flowchart illustrating a numerical simulation method for the performance of recycled concrete according to an embodiment of the present invention. In this embodiment, the numerical simulation method for the performance of recycled concrete includes:

[0090] S1. Obtain recycled concrete and extract recycled aggregate from the recycled concrete. Measure the old mortar adhesion rate, average thickness of the old ITZ, and aggregate gradation of the recycled aggregate. Combine the aggregate gradation, the old mortar adhesion rate, and the average thickness of the old ITZ to generate a geometric distribution framework for the recycled aggregate.

[0091] This invention provides necessary raw materials for the preparation of recycled concrete by obtaining recycled concrete and extracting recycled aggregate from it. The recycled concrete refers to a standardized concrete sample prepared by replacing part or all of the natural aggregate with recycled concrete aggregate (RCA) according to a specific mix proportion. The recycled aggregate refers to the aggregate components separated from the recycled concrete (RAC Specimen) through processes such as physical crushing and screening.

[0092] For example, recycled concrete (150mm cube) of strength grade C30 is prepared as follows: the recycled aggregate is selected from waste concrete after crushing and screening to obtain a continuous gradation of 5~20mm; the new mortar is prepared according to the ratio of cement (P.O42.5):sand:water = 1:1.5:0.45 (mass ratio). In the mix design, the volume replacement method is used to set the replacement rate of recycled aggregate (e.g., 50% replacement of natural coarse aggregate), and additional pre-wetting treatment is carried out to compensate for the water absorption rate of RCA; during the molding process, a vibration molding method with a frequency of 50Hz and an amplitude of 0.5mm is used, followed by standard curing for 28 days in an environment of 20±2℃ and RH≥95%.

[0093] The preparation method described above can effectively guarantee the strength and quality of recycled concrete, providing a reliable sample for the application of recycled aggregates in concrete engineering.

[0094] To visually demonstrate the application of recycled concrete in real-world scenarios and to aid in understanding the spatial relationship between parameters such as new mortar, natural aggregates, and interface transition zones, the following explanation is provided in conjunction with a microscopic structural diagram of recycled concrete:

[0095] See Figure 2The diagram shown is a microscopic structural diagram of recycled concrete used to implement the numerical simulation method for the performance of recycled concrete according to an embodiment of the present invention. It is used to visually demonstrate the spatial distribution of natural aggregates, hardened old mortar layer, and newly hardened mortar inside the recycled concrete, as well as the positional relationship of the transition zone between the old and new interfaces, and to help understand the actual existence form and interaction basis of each component.

[0096] Furthermore, by measuring the old mortar adhesion rate, the average thickness of the old ITZ, and the aggregate gradation of the recycled aggregate, the mix design, pretreatment method, and numerical simulation of recycled concrete can be optimized, thereby improving the performance of recycled concrete. The old mortar adhesion rate refers to the amount of old cement mortar remaining on the surface of the recycled aggregate. The average thickness of the old ITZ refers to the average thickness of the transition zone between the natural aggregate core and the old mortar adhesion layer in the recycled aggregate, which is usually 20~100μm. The aggregate gradation refers to the distribution pattern of particles of different sizes in the recycled aggregate.

[0097] Optionally, the old mortar adhesion rate of the recycled aggregate can be determined by thermal shock method, the average thickness of the old ITZ can be determined by SEM-EDS line scanning, and the aggregate gradation can be determined by standard sieve.

[0098] This invention, by combining the aggregate gradation, the old mortar adhesion rate, and the average thickness of the old ITZ, generates a geometric distribution framework for the recycled aggregate, which can more accurately simulate the mechanical behavior of recycled concrete. The polygonal microstructure refers to a virtual geometric model that describes and simulates the internal microstructure of recycled concrete.

[0099] As an embodiment of the present invention, the step of generating the geometric distribution framework of the recycled aggregate by combining the aggregate gradation, the old mortar adhesion rate, and the average thickness of the old ITZ includes:

[0100] Based on the aggregate gradation, the multi-size spatial layout of the recycled aggregate is identified to construct the initial three-dimensional framework of the recycled aggregate.

[0101] Based on the old mortar adhesion rate, an old mortar coating layer is generated on the aggregate surface of the initial three-dimensional frame to obtain an aggregate-mortar composite frame.

[0102] Based on the average ITZ thickness, an interface transition layer is created at the aggregate-old mortar contact interface of the aggregate-mortar composite frame to generate the target three-dimensional frame.

[0103] The CT scan data and performance data of the recycled aggregate are collected, and the target three-dimensional frame is corrected using the CT scan data and performance data to generate the geometric distribution frame of the recycled aggregate.

[0104] To more intuitively illustrate the geometric distribution of the recycled aggregates, the following explanation is provided in conjunction with a schematic diagram of the geometric distribution framework of the recycled aggregates:

[0105] See Figure 3 The diagram shows a schematic of the geometric distribution framework of recycled aggregates for implementing the numerical simulation method of recycled concrete performance according to an embodiment of the present invention. Through the spatial layout of multi-size recycled aggregates and the position and shape of the aggregate-old mortar contact interface in the schematic diagram, the structural features of multi-size recycled aggregates, interface transition layers and other features can be intuitively presented. The microstructure of recycled aggregates can be accurately constructed by multi-parameter coordination (gradation, adhesion rate, ITZ thickness).

[0106] The multi-size spatial layout refers to the distribution and arrangement of recycled aggregates of different sizes in three-dimensional space, including the relative positions, spacing, and stacking methods between aggregates. The initial three-dimensional framework refers to a three-dimensional model constructed in virtual space based on the multi-size spatial layout of recycled aggregates, containing only recycled aggregate particles. The aggregate surface refers to the specific curved surface structure formed by the outer boundaries of the recycled aggregate particles. The old mortar coating layer refers to a simulated old mortar structure generated on the surface of the recycled aggregates according to the old mortar adhesion rate. The aggregate-old mortar contact interface refers to the interface between the recycled aggregate particles and the attached old mortar coating layer, which is the location where the interface transition layer is formed. The interface transition layer refers to the layer formed at the interface of the recycled aggregate-old mortar composite. The functional layer has gradient structural features. The target three-dimensional framework refers to the complete three-dimensional model that simulates the complex structure of recycled aggregate, formed by adding an old mortar wrapping layer and an interface transition layer on the basis of the initial three-dimensional framework. The CT scan data refers to the tomographic image data of the internal structure of recycled aggregate obtained by CT scanning equipment, which can intuitively present the actual shape and distribution of aggregate, mortar, interface transition zone, etc. The performance data refers to the physical and mechanical property data related to recycled aggregate, such as compressive strength, elastic modulus, water absorption rate, etc. The correction processing refers to the process of comparing the CT scan data and performance data with the target three-dimensional framework in depth, and making precise adjustments and optimizations to the geometric parameters, structural morphology, material properties, etc. in the target three-dimensional framework based on the analysis results.

[0107] Optionally, based on the aggregate gradation, the multi-size spatial layout of the recycled aggregate can be identified by a random placement algorithm; the generation of an old mortar coating layer on the aggregate surface of the initial three-dimensional frame according to the old mortar adhesion rate can be achieved using a geometric offset method; and the correction processing of the target three-dimensional frame using the CT scan data and the performance data can be achieved using digital twin technology.

[0108] S2. Based on the geometric distribution framework, construct the polygonal microstructure of the recycled concrete, calculate the stress distribution value of the polygonal microstructure, use the stress distribution value to locate the stress concentration area of ​​the polygonal microstructure, and identify the ITZ region of the polygonal microstructure according to the average thickness of the old ITZ.

[0109] This invention, through the construction of a polygonal microstructure of recycled concrete based on the aforementioned geometric distribution framework, can realistically and comprehensively present the structural characteristics of recycled concrete at the microscale, making the numerical simulation more closely resemble the actual material and improving the accuracy and reliability of the simulation results. The polygonal microstructure refers to a structural framework formed by dividing and modeling the various components of recycled concrete, such as recycled aggregate, new mortar, old mortar coating layer, and interface transition zone, using polygonal meshes at the microscale.

[0110] As an embodiment of the present invention, constructing the polygonal mesoscopic architecture of the recycled concrete based on the geometric distribution framework includes:

[0111] Extract the recycled aggregate and its geometric phase label corresponding to the geometric distribution framework;

[0112] The aggregate surface, ITZ layer, and old mortar layer of the recycled aggregate are separated from the geometric distribution framework.

[0113] The aggregate surface, the ITZ layer, and the old mortar layer are subjected to triangular meshing to obtain a surface triangular mesh.

[0114] The surface triangular mesh is converted into a tetrahedral volume mesh, and the tetrahedral volume mesh is subjected to material property mapping based on the geometric phase label to obtain the mesostructure.

[0115] Acquire microstructural images of the recycled concrete and extract the aggregate-mortar-ITZ distribution characteristics from the microstructural images;

[0116] Construct a spatial mapping relationship between the aggregate-mortar-ITZ distribution characteristics and the microstructure;

[0117] Based on the spatial mapping relationship, the positions of the mesh nodes in the microstructure are optimized to obtain the polygonal microstructure.

[0118] The geometric phase label refers to a label used to identify the material properties and physical characteristics of recycled aggregate and its components (such as aggregate core, old mortar layer, and ITZ layer). The aggregate surface refers to the outermost boundary of the recycled aggregate particles. The ITZ layer, or interface transition zone, is a region with special structure and properties between the recycled aggregate and the old mortar. The old mortar layer refers to the old mortar adhering to the surface of the recycled aggregate. The triangular mesh partitioning process refers to the process of dividing the complex geometric structures of the aggregate surface, ITZ layer, and old mortar layer into many small triangular mesh units. The tetrahedral volume mesh refers to extending the two-dimensional surface mesh to three-dimensional space based on the triangular mesh, forming a volume mesh composed of many tetrahedra. The material property mapping process refers to mapping the corresponding physical and mechanical property parameters (such as elastic modulus, Poisson's ratio, density, etc.) according to the material category identified by the geometric phase label. The process of assigning microstructure (such as degree, etc.) to each element of a tetrahedral volume grid, where the microstructure image refers to an image of recycled concrete at a microscale obtained through equipment such as microscopes and CT scans, the aggregate-mortar-ITZ distribution features refer to the key microstructure feature vectors of recycled aggregate, mortar, and ITZ layers extracted from the microstructure image based on image recognition and pattern recognition technologies, the spatial mapping relationship refers to an end-to-end spatial mapping model based on deep learning, which automatically learns the complex spatial correspondence between a large number of microstructure images and corresponding microstructure data, and the grid node position refers to an intelligent node in the tetrahedral volume grid with adjustable parameters, each node equipped with optimizable parameters such as coordinate offset and weight coefficient, and the position optimization process refers to the process of adjusting and optimizing the coordinates of the grid nodes according to the spatial mapping relationship between the microstructure image and the microstructure. For example, according to the mapping relationship, the grid node positions of the initial microstructure are adjusted by the vertex displacement method to make the geometric features consistent with the microstructure image.

[0119] Optionally, the triangular meshing of the aggregate surface, the ITZ layer, and the old mortar layer can be implemented using the constrained Delaunay triangular meshing algorithm. The conversion of the surface triangular mesh into a tetrahedral volume mesh can be implemented using the TetGen algorithm. The material property mapping of the tetrahedral volume mesh based on the geometric phase label can be implemented using the property gradient transition algorithm. The spatial mapping relationship between the aggregate-mortar-ITZ distribution characteristics and the microstructure can be constructed using a non-rigid registration algorithm.

[0120] Furthermore, by calculating the stress distribution value of the polygonal microstructure, the embodiments of the present invention can intuitively present the concentrated areas and transmission paths of stress in each phase material, thereby revealing the weak links in the material properties. The stress distribution value refers to the magnitude and direction of the stress borne by each part (such as recycled aggregate, new mortar, old mortar and interface transition zone, etc.) in the polygonal microstructure of recycled concrete.

[0121] Optionally, the stress distribution values ​​of the polygonal microstructure can be calculated using adaptive mesh refinement techniques and high-order finite element methods.

[0122] This invention utilizes the stress distribution value to locate the stress concentration area of ​​the polygonal microstructure, which helps to deepen the understanding of the failure mechanism of recycled concrete and provides a key basis for improving material performance. The stress concentration area refers to a local location in the microstructure model of recycled concrete where the stress is significantly higher than the surrounding area due to factors such as differences in the mechanical properties of each component phase (e.g., different elastic modulus and Poisson's ratio), irregular geometric shape (different aggregate shapes, uneven thickness of interface transition zone), and the presence of micro-defects (pores and cracks in old mortar).

[0123] Optionally, the location of stress concentration areas in the polygonal microstructure using the stress distribution value can be determined by setting a stress threshold. For example, an adaptive threshold dynamic adjustment technique can be used to calculate the stress concentration judgment threshold for each region in real time based on the material phase properties and structural characteristics, thereby identifying the stress concentration areas.

[0124] Furthermore, by identifying the ITZ region of the polygonal microstructure based on the average thickness of the old ITZ, the embodiments of the present invention can more accurately simulate the stress transmission path and the expansion path of damage from the starting point. The ITZ region refers to a layer with a special structure and performance gradient formed between recycled aggregate and new mortar in recycled concrete, and between old mortar and new mortar on the surface of recycled aggregate.

[0125] As an embodiment of the present invention, identifying the ITZ region of the polygonal microstructure based on the average thickness of the old ITZ includes:

[0126] Retrieve the recycled concrete corresponding to the polygonal microstructure;

[0127] The internal three-dimensional structure of the recycled concrete was obtained, and the mechanical properties of the recycled concrete were measured. Simultaneously, microscopic morphological images of the recycled concrete were acquired.

[0128] Based on the microscopic morphology image, the aggregate-mortar interface of the recycled concrete is identified, and the gray-level co-occurrence matrix of the aggregate-mortar interface is calculated.

[0129] Based on the gray-level co-occurrence matrix, the interface texture features of the recycled concrete are extracted;

[0130] The density distribution characteristics of the recycled concrete are extracted from the internal three-dimensional structure, and the modulus gradient characteristics of the recycled concrete are identified based on the mechanical properties.

[0131] By combining the average thickness of the old ITZ, the interface texture features, the density distribution features, and the modulus gradient features, the ITZ region of the polygonal microstructure is identified.

[0132] The internal three-dimensional structure refers to the morphology and structure of the recycled concrete in three-dimensional space obtained by scanning the recycled concrete using techniques such as X-ray computed tomography (CT). The mechanical properties refer to the properties exhibited by the recycled concrete under stress, including but not limited to compressive strength, tensile strength, elastic modulus, and Poisson's ratio. The microscopic morphology image refers to the image obtained by magnifying and photographing the internal microstructure of the recycled concrete using microscopic observation equipment such as scanning electron microscope (SEM). The aggregate-mortar interface refers to the boundary area where the recycled aggregate and mortar in the recycled concrete come into contact. The gray-level co-occurrence matrix refers to a statistical matrix used to describe the distribution characteristics of gray-level pixels in an image. In the microscopic morphology image of recycled concrete, it reflects the texture information of the image by calculating the co-occurrence probability of different gray-level pixels in a specific direction and distance. The interface texture feature refers to the parameters extracted from the gray-level co-occurrence matrix that can describe the microscopic texture characteristics of the aggregate-mortar interface. The density distribution feature refers to the distribution law and differences of density in different parts of the recycled concrete. The modulus gradient feature refers to the spatial variation trend and gradient of the elastic modulus inside the recycled concrete.

[0133] Optionally, the mechanical properties of the recycled concrete can be determined by nanoindentation testing. Based on the mechanical properties, the modulus gradient characteristics of the recycled concrete can be identified by fitting nanoindentation load-displacement curves. Combining the average thickness of the old ITZ, the interface texture characteristics, the density distribution characteristics, and the modulus gradient characteristics, the ITZ regions of the polygonal mesostructure can be identified by a random forest classification model. For example, the average thickness of the old ITZ can be used as a constraint condition, and the interface texture, density distribution, and modulus gradient characteristics can be input into a random forest classifier to predict the ITZ probability of the mesh cells of the polygonal mesostructure. Cells with a probability > 0.5 are marked as ITZ regions.

[0134] S3. Identify the initial damage point of the polygonal microstructure from the stress concentration area and the ITZ region, use the initial damage point to set the damage initiation position determiner of the polygonal microstructure, identify the initial expansion path of the initial damage point, and track the expansion trajectory of the initial expansion path in the polygonal microstructure based on the initial damage point.

[0135] By identifying the initial damage points of the polygonal microstructure from the stress concentration zone and the ITZ region, this embodiment of the invention can ensure that the numerical simulation can accurately reflect the microstructure and mechanical behavior of recycled concrete. The initial damage points refer to the locations in the polygonal microstructure of recycled concrete where local damage (such as microcrack initiation, interface debonding, and material plastic deformation) first occurs due to factors such as differences in the properties of different phases of the material, stress concentration, and micro-defects.

[0136] As an embodiment of the present invention, identifying the initial damage points of the polygonal microstructure from the stress concentration region and the ITZ region includes:

[0137] Calculate the normalized stress gradient between adjacent elements within the stress concentration region;

[0138] The degree of degradation in the ITZ region is quantified to obtain the ITZ degradation degree;

[0139] Calculate the percentage of microcracks per unit area within the ITZ region;

[0140] Based on the normalized stress gradient, the ITZ degradation degree, and the proportion of microcracks, a damage accumulation index for the polygonal mesostructure is constructed.

[0141] Set a damage threshold for the damage accumulation index, and use the damage threshold to determine the potential damage initiation region of the polygonal mesostructure;

[0142] Damage initiation seed points of the polygonal mesostructure are identified from the potential damage initiation region;

[0143] Abnormal points are identified from the damage initiation seed points, and the abnormal points are removed to obtain the initial damage points of the polygonal microstructure.

[0144] Wherein, adjacent units refer to two units sharing an edge or face within the stress concentration zone; the normalized stress gradient refers to the ratio of the stress difference between adjacent units to the characteristic length of the unit, normalized by the material reference stress (such as compressive strength) to quantify the severity of stress concentration; the degree of degradation refers to the degree of mechanical property attenuation in the ITZ (interface transition zone) due to material composition inhomogeneity (such as high porosity or disordered crystal orientation); the quantification process refers to the numerical characterization of the ITZ degradation degree using a multi-parameter coupling algorithm; the unit area refers to the characteristic area unit defined in the polygonal mesoscopic architecture, such as 100μm×100μm; the microcrack ratio refers to the ratio of the projected area of ​​microcracks (usually referring to cracks with a length <100μm) to the characteristic area per unit area; and the... The damage accumulation index refers to a comprehensive parameter formed by weighting or functional coupling of stress gradient, ITZ deterioration degree, and microcrack ratio. The damage threshold refers to the critical value of the damage accumulation index determined by uniaxial tensile / compression test. When the damage accumulation index of a local area exceeds this value, it is determined that damage initiation may occur. The potential damage initiation zone refers to a continuous area where the damage accumulation index exceeds the threshold, containing multiple possible initial damage points. The damage initiation seed point refers to the local damage accumulation index maxima identified by a density peak clustering algorithm (such as K-Density) within the potential damage zone. The outlier refers to a point with a significantly different damage accumulation index from the surrounding seed points and an isolated spatial distribution. The removal process refers to the process of identifying and removing outliers through spatial clustering (such as DBSCAN).

[0145] Optionally, the damage threshold of the damage accumulation index can be set through Weibull statistical analysis. The process of removing the outliers to obtain the initial damage points of the polygonal microstructure can be achieved through an iterative outlier detection algorithm. The specific implementation steps are as follows: constructing a KD tree index of the spatial distribution of the damage initiation seed points; calculating the local density and distance threshold of each point; removing points that meet the outlier conditions and recalculating the damage correlation of the remaining points until convergence.

[0146] Furthermore, by utilizing the initial damage point to set the damage initiation location determiner of the polygonal microstructure, the embodiments of the present invention can provide accurate initial damage location and damage pattern for numerical simulation, thereby improving the accuracy of the simulation. The damage initiation location determiner is a tool used to predict and identify the specific location where damage begins to appear in a material or structure.

[0147] In an optional embodiment of the present invention, based on the normalized stress gradient, the ITZ degradation degree, and the microcrack ratio, the damage accumulation index of the polygonal mesostructure is constructed using the following formula:

[0148] ,

[0149] in, A measure of damage accumulation in polygonal microstructures. This represents the weight coefficient of the e-th type of mesocell in the polygonal mesostructure. This represents the normalized stress gradient of the e-th type of mesoscopic element. This represents the ITZ degradation degree of the e-th type of mesocell. The material correlation coefficient representing the degree of ITZ degradation. This represents the proportion of microcracks in the e-th type of mesoscopic unit. The material correlation coefficient representing the proportion of microcracks. This represents the effective damage area of ​​the e-th type of mesocell. Let n represent the reference area of ​​the e-th mesocell, where e represents the mesocell index and n represents the total number of mesocell categories. The material correlation coefficient represents the normalized stress gradient.

[0150] It should be noted that in this application, the formula is used... The damage contribution of fine elements such as aggregate corners and the transition zone between old and new interfaces is distinguished using formulas. Identifying the synergistic damage effect of stress concentration and interface degradation can enable the quantification of damage in multiphase heterogeneous structures of recycled concrete, and improve the correlation between damage accumulation index and macroscopic strength decay.

[0151] As an embodiment of the present invention, the step of setting the damage initiation position determiner of the polygonal mesostructure using the initial damage point includes:

[0152] Extract the new ITZ region and the old ITZ region corresponding to the polygonal mesoscopic architecture;

[0153] Based on the initial damage point, identify the local stress field and microcrack layout corresponding to the new ITZ region and the old ITZ region;

[0154] Identify the initial damage point coordinate set corresponding to the initial damage point to construct the damage point spacing matrix of the polygonal mesostructure;

[0155] The stress concentration degree corresponding to the new ITZ region and the old ITZ region was measured respectively, and the performance degradation rate corresponding to the new ITZ region and the old ITZ region was analyzed based on the microcrack layout.

[0156] Based on the damage point spacing matrix, the stress concentration degree, and the performance degradation rate, the damage feature vector of the polygonal mesostructure is extracted.

[0157] Based on the damage feature vector, a damage determination rule for the polygonal mesoscopic architecture is constructed.

[0158] Based on the damage determination rule, an adaptive threshold is set for the polygonal mesostructure;

[0159] Based on the adaptive threshold and the initial set of damage point coordinates, a damage propagation network for the polygonal mesoscopic architecture is generated.

[0160] Based on the damage transmission network, a dual-mode damage verification mechanism is set for the polygonal mesoscopic architecture;

[0161] Based on the damage transmission network and the dual-mode damage verification mechanism, a damage initiation location determiner for the polygonal mesoscopic architecture is set.

[0162] The term "new ITZ zone" refers to the interface transition zone between old mortar (from demolished old concrete) and aggregate; "old ITZ zone" refers to the interface transition zone between fresh mortar and old mortar; "local stress field" refers to the stress distribution state within a 200μm range around the damage point; "microcrack layout" refers to the spatial distribution characteristics of microcracks within the microscopic region; "initial damage point coordinate set" refers to the three-dimensional coordinate set of the first identified potential damage locations; "damage point spacing matrix" refers to the matrix describing the spatial distance between each damage point, for example, the spacing matrix of three damage points is [[0,15,28],[15,0,13],[28,13,0]]; "stress concentration degree" refers to the ratio of the highest local stress to the average far-field stress, such as a stress concentration ratio of 2.4 times in the old interface zone of a sample; "performance degradation rate" refers to the rate of change of material properties (such as elastic modulus) over time, such as a degradation rate of 50% faster in the old interface zone than in the new interface zone of a sample, which can be obtained through nanoindentation testing; and "damage..." The damage feature vector refers to a comprehensive set of parameters characterizing the damage state. For example, a typical feature vector form is [old area stress ratio 2.4, deterioration rate 0.8, spacing 0.15 | new area stress ratio 1.9, deterioration rate 0.5, spacing 0.22]. The damage judgment rule refers to the judgment criteria set based on the damage feature vector. For example, when the stress ratio of the old interface area exceeds 2.2 and the deterioration rate is greater than 0.7, it is judged as dangerous damage. The adaptive threshold refers to the damage critical value dynamically adjusted according to the material state. For example, for components containing 40% recycled aggregate, the threshold adjustment cycle is extended to 28 hours. The damage transmission network refers to a topological model constructed with damage points as nodes and propagation paths as edges. The dual-mode damage verification mechanism refers to a dual-mode verification method used to verify the accuracy of the damage transmission network, including morphological verification and energy verification. For example, the spatial overlap between the network-predicted crack path and the synchrotron radiation CT scan results must be ≥85%; the relative error between the damage energy consumption calculated by the network and the cumulative acoustic emission energy is ≤15%, otherwise, the rule base is updated.

[0163] Optionally, the stress concentration corresponding to the new ITZ region and the old ITZ region can be determined by digital image correlation technology, the damage point spacing matrix of the polygonal microstructure can be constructed using Delaunay triangulation, the damage transmission network of the polygonal microstructure based on the adaptive threshold and the initial damage point coordinate set can be generated using a probabilistic graphical model, and the damage determination rule of the polygonal microstructure based on the damage feature vector can be determined by a support vector machine.

[0164] By identifying the initial propagation path of the initial damage point, this invention can identify areas prone to damage and key factors for damage propagation in recycled concrete, thereby guiding material improvement and optimization design. The initial propagation path refers to the trajectory or direction of damage or crack propagation from a starting point, which can be determined by numerical manifold method.

[0165] Furthermore, by tracking the expansion trajectory of the initial expansion path in the polygonal microstructure based on the initial damage point, the embodiments of the present invention can improve the reliability assessment efficiency of the polygonal microstructure of recycled concrete and achieve early warning of damage expansion risk. The expansion trajectory refers to the path followed by a crack, damage or other defect as it expands from a starting point inside or on the surface of the material.

[0166] As an embodiment of the present invention, the step of tracing the expansion trajectory of the initial expansion path in the polygonal mesostructure based on the initial damage point includes:

[0167] Based on the initial damage point, mark the new-old ITZ stress concentration areas of the polygonal mesostructure;

[0168] Construct a dual-channel analysis unit for the initial extension path in the new-old ITZ stress concentration zone, and configure the real-time tracking node of the dual-channel analysis unit;

[0169] Based on the dual-channel analysis unit and the real-time tracking node, the trajectory topology network of the polygonal mesoscopic architecture is set;

[0170] Based on the trajectory topology network, a damage evolution monitor with the polygonal mesoscopic architecture is configured;

[0171] The damage evolution monitor is used to track the expansion trajectory of the initial expansion path in the polygonal microstructure.

[0172] The stress concentration zone between the new and old ITZs refers to the stress concentration area in the transition zone between the new and old interfaces in the polygonal microstructure caused by material property mismatch (such as differences in elastic modulus and coefficient of thermal expansion). The new ITZ refers to the interface transition zone dynamically formed during loading, such as grain boundaries / phase boundaries where crack propagation newly contacts. The old ITZ refers to initial material defects or pre-formed interfaces, such as the original interface after casting. The dual-channel analysis unit is a dual analysis module used to simultaneously analyze the mechanical behavior and damage evolution of the initial propagation path in the new and old ITZ regions, achieved through a dynamic weight matrix (weight coefficients λ∈[0.1,0.9] adaptively adjusted). The collaborative analysis of mechanical models and data-driven approaches involves real-time tracking nodes, which are monitoring points deployed in the old and new ITZ stress concentration zones to collect damage-related data such as stress and displacement in real time. For example, 3-5 key tracking nodes are set up in the old and new stress concentration zones. The trajectory topology network refers to a network model that abstracts the damage propagation path in the polygonal microstructure as a graph structure, with nodes representing key locations and edges representing path connections. The damage evolution monitor is a system used to monitor the propagation process of the initial propagation path in the polygonal microstructure. This system uses a recurrent neural network (RNN) in the time dimension to process historical monitoring data and predict future... The expansion trend within s; the three-dimensional damage field is reconstructed in the spatial dimension using digital volume correlation (DVC) technology, with a resolution of submicron level (<0.8μm).

[0173] Optionally, the initial propagation path can be constructed using a dual-channel analysis unit in the new-old ITZ stress concentration zone by combining extended finite element method (XFEM) and convolutional neural network (CNN), such as calculating the crack tip stress intensity factor based on XFEM. The displacement field gradient in the DIC image is processed by a convolutional neural network (CNN) to extract crack tip propagation features, and the real-time tracking node of the dual-channel analysis unit can be configured using a micron-scale fiber optic grating (FBG) sensor. The damage evolution monitor based on the trajectory topology network and the polygonal microstructure can be configured using micro-strain gauges and acoustic emission sensors.

[0174] S4. Based on the old mortar adhesion rate and the average thickness of the old ITZ, set the five-phase constitutive relationship of the polygonal microstructure, apply an external load to the polygonal microstructure, and combine the external load and the five-phase constitutive relationship to determine the damage variable of the polygonal microstructure under the external load.

[0175] This invention, by setting the five-phase constitutive relationship of the polygonal microstructure based on the adhesion rate of the old mortar and the average thickness of the old ITZ, can realize multi-scale damage mapping of recycled concrete, improve the accuracy of performance prediction of recycled concrete, and guide the optimized design of recycled aggregates. The five-phase constitutive relationship refers to the interaction between different phases inside the material and the relationship of the overall material mechanical behavior.

[0176] As an embodiment of the present invention, the step of setting the five-phase constitutive relationship of the polygonal microstructure based on the old mortar adhesion rate and the average thickness of the old ITZ includes:

[0177] Based on the old mortar adhesion rate and the average thickness of the old ITZ, the material phase boundaries of the polygonal microstructure are identified.

[0178] Based on the material phase boundaries, the five-phase material of the polygonal mesostructure is determined;

[0179] Construct the stiffness transfer matrix of the five-phase material;

[0180] Based on the stiffness transfer matrix, the stress distribution weights of the polygonal mesostructure are set;

[0181] Configure the multi-scale constitutive units of the polygonal mesoscopic architecture according to the stress allocation weights;

[0182] The five-phase constitutive relation of the polygonal mesoscopic architecture is set through the multi-scale constitutive unit.

[0183] The material phase boundary refers to the physical interface between different material components in the microstructure of recycled concrete, such as the boundary between natural aggregate and old mortar, and between old mortar and new mortar. The five-phase material refers to the five material components divided in the microstructure of recycled concrete, including natural aggregate, old mortar, new mortar, old interface transition zone (old ITZ), and new interface transition zone (new ITZ). The stiffness transfer matrix is ​​a matrix describing the stiffness coupling relationship between the five-phase materials, used to calculate the stress transfer law in each phase material. The stress distribution weight is the stress proportion coefficient allocated to each phase material when under stress, calculated based on the stiffness proportion of each phase, used to describe the stress distribution law in the five-phase materials. The multi-scale constitutive unit refers to an intelligent coupling unit that integrates the microscopic five-phase material properties and macroscopic mechanical behavior based on small-package transformation.

[0184] Optionally, based on the old mortar adhesion rate and the average thickness of the old ITZ, the material phase boundaries of the polygonal microstructure can be identified by combining CT scanning and deep learning methods, and the stiffness transfer matrix of the five-phase material can be constructed by a 25th-order asymmetric tensor matrix.

[0185] Furthermore, in this embodiment of the invention, by applying external loads to the polygonal microstructure and combining the external loads with the five-phase constitutive relation, the damage variables of the polygonal microstructure under the external loads are determined. This helps to understand the behavior of materials under different load conditions, thereby enabling accurate simulation of material response. The external loads refer to the external forces applied to the recycled concrete structure or material. In the polygonal microstructure, the external loads need to be transferred to the structure through boundary conditions, such as applying displacement or force to the boundary nodes of the polygonal elements. The damage variables refer to physical quantities used to quantify the degree of damage within the material, including scalar damage variables and tensor damage variables. For example, the scalar damage variable ranges from 0 to 1. When the value is 0, it indicates that the material is intact, and when the value is 1, it indicates that the material is completely destroyed.

[0186] Optionally, by combining the external load and the five-phase constitutive relation, the damage variable of the polygonal mesostructure under the external load can be determined experimentally, such as through a macro-mesocorrelation test.

[0187] S5. Based on the damage variables, generate a damage cloud map of the polygonal microstructure. Combine the damage cloud map, the path expansion trajectory, the damage initiation location determiner, and the polygonal microstructure to perform performance numerical simulation processing of the recycled concrete and obtain performance numerical simulation results.

[0188] This invention generates a damage cloud map of the polygonal microstructure based on the damage variables, which can effectively reveal the internal failure mechanism of the material and provide an intuitive basis for numerical simulation of the performance of recycled concrete. The damage cloud map is a visual graphic that intuitively displays the spatial distribution of the degree of damage inside the polygonal microstructure material through color gradient.

[0189] As an embodiment of the present invention, generating a damage cloud map of the polygonal mesoscopic architecture based on the damage variable includes:

[0190] Based on the damage variables, a damage level threshold is set for the polygonal mesostructure;

[0191] Based on the damage level threshold, identify the damage level regions of the polygonal mesostructure;

[0192] Construct geometric mapping units corresponding to the damage level region;

[0193] Based on the geometric mapping unit, the graphics generation rules for the polygonal microstructure are set;

[0194] Configure the dynamic visualization engine for the polygonal microstructure based on the graphics generation rules;

[0195] Based on the dynamic visualization engine, a damage cloud map of the polygonal microstructure is generated.

[0196] The damage level threshold refers to the critical numerical standard used to classify the degree of material damage. For example, the damage variable D=0.3 is set as the boundary value between slight damage and moderate damage. The damage level region refers to the material region divided according to the damage level threshold. The degree of damage within the same region belongs to the same level. For example, the region D∈[0.3,0.6] is defined as the moderate damage region. The geometric mapping unit refers to the basic unit that transforms the geometric features (such as shape, size, and position) of the damage level region into visual graphic elements. For example, a polygon region is mapped to a mesh surface or voxel. The graphic generation rule refers to the rule that defines how the damage region is transformed into a visual graphic, such as the setting method of visual attributes such as color, transparency, and texture. The dynamic visualization engine refers to a multi-scale visualization computing platform used to generate and display damage cloud maps in real time.

[0197] Optionally, the geometric mapping unit corresponding to the damage level region can be constructed by combining finite element mesh and computer graphics, and the dynamic visualization engine of the polygonal microstructure can be configured through a CPU-GPU collaborative computing architecture according to the graphics generation rules.

[0198] Furthermore, in this embodiment of the invention, by combining the damage cloud map, the expansion trajectory, the damage initiation location determiner, and the polygonal microstructure, the performance numerical simulation processing of the recycled concrete is performed to obtain performance numerical simulation results. This can more accurately simulate the stress distribution and damage evolution process of recycled concrete in practical applications, significantly improve the prediction accuracy of recycled concrete performance, reduce reliance on actual experiments, thereby improving R&D efficiency and reducing costs. At the same time, it can optimize the microstructure design of recycled concrete, improve the mechanical properties and durability of the material. The performance numerical simulation processing refers to the process of simulating and analyzing the physical, mechanical, and other properties of recycled concrete through computer numerical calculation methods.

[0199] As an embodiment of the present invention, the performance numerical simulation processing of the recycled concrete is performed by combining the damage cloud map, the expansion trajectory, the damage initiation location determiner, and the polygonal microstructure to obtain the performance numerical simulation results, including:

[0200] Based on the aforementioned polygonal microstructure, the multi-scale material composition elements of the recycled concrete were analyzed.

[0201] The mechanical properties of the constituent elements of the multi-scale material were analyzed;

[0202] Based on the multi-scale material composition elements and the mechanical properties, the damage evolution characteristic parameters of the recycled concrete are set;

[0203] The initial damage core area of ​​the recycled concrete is located using the damage initiation location determiner.

[0204] Based on the aforementioned expansion trajectory, a multi-crack collaborative expansion network for the recycled concrete is constructed.

[0205] Based on the damage cloud map, a damage distribution characterization system for the recycled concrete is created;

[0206] By combining the damage evolution characteristic parameters, the initial damage core region, the multi-crack collaborative propagation network, and the damage distribution characterization system, a full-cycle performance evolution map of the recycled concrete is generated.

[0207] Based on the full-cycle performance evolution map, the performance numerical simulation of the recycled concrete is performed to obtain the performance numerical simulation results.

[0208] The multi-scale material components refer to the material constituent units of recycled concrete at different scales, including the overall structure at the macro scale, the polygonal aggregate / new and old mortar / interface transition zone at the meso scale, and the crystals / pores at the micro scale. The mechanical properties refer to the physical properties exhibited by recycled concrete and its constituent elements under stress, such as elastic modulus, compressive strength, Poisson's ratio, etc. The damage evolution characteristic parameters refer to the key indicators used to describe the damage development process of recycled concrete, such as damage initiation threshold, propagation rate, stiffness degradation coefficient, etc. The initial damage core region refers to the local area where recycled concrete first shows damage under external load, such as the interface transition zone, aggregate edges, etc. The multi-crack collaborative propagation network refers to the connected network formed by multiple cracks in recycled concrete influencing each other and propagating together. The damage distribution characterization system refers to the model used to describe the spatial distribution of damage inside recycled concrete. The full-cycle performance evolution map refers to the spatiotemporal map of multi-scale performance evolution of recycled concrete from the initial state to the entire process of failure.

[0209] Optionally, based on the extended trajectory, the multi-crack collaborative propagation network of the recycled concrete can be constructed using a phase-field fracture model; based on the damage cloud map, the damage distribution characterization system of the recycled concrete can be created using a U-Net network model; and combining the damage evolution characteristic parameters, the initial damage core region, the multi-crack collaborative propagation network, and the damage distribution characterization system, the full-cycle performance evolution map of the recycled concrete can be created using the Neo4j graph database.

[0210] Compared to the problems described in the background art, the embodiments of the present invention, by measuring the old mortar adhesion rate, average thickness of the old ITZ, and aggregate gradation of the recycled aggregate, can optimize the mix design, pretreatment methods, and numerical simulation of recycled concrete, thereby improving the performance of recycled concrete. Furthermore, by combining the aggregate gradation, the old mortar adhesion rate, and the average thickness of the old ITZ to generate a geometric distribution framework of the recycled aggregate, the embodiments of the present invention can more accurately simulate the mechanical behavior of recycled concrete. By constructing a polygonal microstructure of the recycled concrete based on the geometric distribution framework, the embodiments of the present invention can realistically and comprehensively present the structural characteristics of recycled concrete at the microscale, making the numerical simulation more closely resemble the actual material and improving the accuracy and reliability of the simulation results. Furthermore, by using the stress distribution values ​​to locate the stress concentration areas of the polygonal microstructure and identifying the ITZ regions of the polygonal microstructure based on the average thickness of the old ITZ, the embodiments of the present invention help to deeply understand the failure mechanism of recycled concrete, thereby more accurately simulating the stress transmission path and the expansion path of damage from the starting point. This invention provides a key basis for improving material performance. In this embodiment, by using the initial damage point to set the damage initiation location determiner of the polygonal microstructure, the accurate initial damage location and damage mode can be provided for numerical simulation, thereby improving the accuracy of the simulation. Furthermore, by tracking the expansion trajectory of the initial expansion path in the polygonal microstructure based on the initial damage point, this invention can improve the reliability assessment efficiency of the polygonal microstructure of recycled concrete and achieve early warning of damage expansion risk. In this embodiment, by setting the five-phase constitutive relationship of the polygonal microstructure according to the old mortar adhesion rate and the average thickness of the old ITZ, multi-scale damage mapping of recycled concrete can be achieved, improving the accuracy of recycled concrete performance prediction and guiding the optimized design of recycled aggregates. Furthermore, by applying external loads to the polygonal microstructure and combining the external loads and the five-phase constitutive relationship, the damage variables of the polygonal microstructure under the external loads are measured, which helps to understand the behavior of materials under different load conditions, thereby enabling accurate simulation of material response.This invention, through generating a damage cloud map of the polygonal mesostructure based on the damage variables, can effectively reveal the internal failure mechanism of the material, providing an intuitive basis for numerical simulation of recycled concrete performance. Finally, by combining the damage cloud map, the expansion trajectory, the damage initiation location determiner, and the polygonal mesostructure, this invention performs numerical simulation of the recycled concrete performance, obtaining performance simulation results. This allows for more accurate simulation of the stress distribution and damage evolution process of recycled concrete in practical applications, significantly improving the prediction accuracy of recycled concrete performance, reducing reliance on actual experiments, thereby improving R&D efficiency and reducing costs. Simultaneously, it can optimize the microstructure design of recycled concrete, improving the material's mechanical properties and durability. Therefore, the numerical simulation method for recycled concrete performance provided by this invention can improve the accuracy of recycled concrete performance simulation.

[0211] Example 2:

[0212] like Figure 4 The diagram shown is a functional block diagram of a numerical simulation system for the performance of recycled concrete according to the present invention.

[0213] The recycled concrete performance numerical simulation system 300 described in this invention can be installed in an electronic device. Depending on the functions implemented, the recycled concrete performance numerical simulation system may include an aggregate distribution module 301, a microstructure generation module 302, a damage tracking module 303, a five-phase relationship identification module 304, and a performance numerical simulation module 305. The module described in this invention can also be referred to as a unit, which refers to a series of computer program segments that can be executed by the processor of an electronic device and can perform a fixed function, and which are stored in the memory of the electronic device.

[0214] In this embodiment of the invention, the functions of each module / unit are as follows:

[0215] The aggregate distribution module 301 is used to obtain recycled concrete, extract recycled aggregate from the recycled concrete, measure the old mortar adhesion rate, the average thickness of the old ITZ and the aggregate gradation of the recycled aggregate, and generate the geometric distribution framework of the recycled aggregate by combining the aggregate gradation, the old mortar adhesion rate and the average thickness of the old ITZ.

[0216] The microstructure generation module 302 is used to construct a polygonal microstructure of the recycled concrete based on the geometric distribution framework, calculate the stress distribution value of the polygonal microstructure, locate the stress concentration area of ​​the polygonal microstructure using the stress distribution value, and identify the ITZ region of the polygonal microstructure based on the average thickness of the old ITZ.

[0217] The damage tracking module 303 is used to identify the initial damage point of the polygonal microstructure from the stress concentration area and the ITZ region, use the initial damage point to set the damage start position determiner of the polygonal microstructure, identify the initial expansion path of the initial damage point, and track the expansion trajectory of the initial expansion path in the polygonal microstructure based on the initial damage point.

[0218] The five-phase relationship identification module 304 is used to set the five-phase constitutive relationship of the polygonal microstructure based on the old mortar adhesion rate and the average thickness of the old ITZ, apply an external load to the polygonal microstructure, and combine the external load and the five-phase constitutive relationship to determine the damage variable of the polygonal microstructure under the external load.

[0219] The performance numerical simulation module 305 is used to generate a damage cloud map of the polygonal microstructure based on the damage variable, and to perform performance numerical simulation processing of the recycled concrete by combining the damage cloud map, the expansion trajectory, the damage initiation position determiner and the polygonal microstructure to obtain performance numerical simulation results.

[0220] In detail, the modules in the numerical simulation system 300 for the performance of recycled concrete described in this embodiment of the invention employ the same methods as described above. Figure 1 The method is the same as the numerical simulation method for the performance of recycled concrete described in the article, and can produce the same technical effect, so it will not be repeated here.

[0221] 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 present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0222] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A numerical simulation method for the performance of recycled concrete, characterized in that, The method includes: Obtain recycled concrete and extract recycled aggregate from the recycled concrete. Measure the old mortar adhesion rate, average thickness of the old ITZ, and aggregate gradation of the recycled aggregate. Combine the aggregate gradation, the old mortar adhesion rate, and the average thickness of the old ITZ to generate a geometric distribution framework for the recycled aggregate. Based on the geometric distribution framework, a polygonal microstructure of the recycled concrete is constructed, the stress distribution value of the polygonal microstructure is calculated, the stress concentration area of ​​the polygonal microstructure is located using the stress distribution value, and the ITZ region of the polygonal microstructure is identified based on the average thickness of the old ITZ. The initial damage point of the polygonal microstructure is identified from the stress concentration area and the ITZ region. The damage initiation position determiner of the polygonal microstructure is set using the initial damage point. The initial expansion path of the initial damage point is identified. Based on the initial damage point, the expansion trajectory of the initial expansion path in the polygonal microstructure is tracked. Based on the old mortar adhesion rate and the average thickness of the old ITZ, the five-phase constitutive relationship of the polygonal microstructure is set. An external load is applied to the polygonal microstructure, and the damage variable of the polygonal microstructure under the external load is determined by combining the external load and the five-phase constitutive relationship. Based on the damage variables, a damage cloud map of the polygonal microstructure is generated. Combining the damage cloud map, the expansion trajectory, the damage initiation location determiner, and the polygonal microstructure, the performance numerical simulation of the recycled concrete is performed to obtain the performance numerical simulation results.

2. The numerical simulation method for the performance of recycled concrete as described in claim 1, characterized in that, The process of generating the geometric distribution framework of the recycled aggregate by combining the aggregate gradation, the old mortar adhesion rate, and the average thickness of the old ITZ includes: Based on the aggregate gradation, the multi-size spatial layout of the recycled aggregate is identified to construct the initial three-dimensional framework of the recycled aggregate. Based on the old mortar adhesion rate, an old mortar coating layer is generated on the aggregate surface of the initial three-dimensional frame to obtain an aggregate-mortar composite frame. Based on the average ITZ thickness, an interface transition layer is created at the aggregate-old mortar contact interface of the aggregate-mortar composite frame to generate the target three-dimensional frame. The CT scan data and performance data of the recycled aggregate are collected, and the target three-dimensional frame is corrected using the CT scan data and performance data to generate the geometric distribution frame of the recycled aggregate.

3. The numerical simulation method for the performance of recycled concrete as described in claim 1, characterized in that, The construction of the polygonal mesoscopic architecture of the recycled concrete based on the geometric distribution framework includes: Extract the recycled aggregate and its geometric phase label corresponding to the geometric distribution framework; The aggregate surface, ITZ layer, and old mortar layer of the recycled aggregate are separated from the geometric distribution framework. The aggregate surface, the ITZ layer, and the old mortar layer are subjected to triangular meshing to obtain a surface triangular mesh. The surface triangular mesh is converted into a tetrahedral volume mesh, and the tetrahedral volume mesh is subjected to material property mapping based on the geometric phase label to obtain the mesostructure. Acquire microstructural images of the recycled concrete and extract the aggregate-mortar-ITZ distribution characteristics from the microstructural images; Construct a spatial mapping relationship between the aggregate-mortar-ITZ distribution characteristics and the microstructure; Based on the spatial mapping relationship, the positions of the mesh nodes in the microstructure are optimized to obtain the polygonal microstructure.

4. The numerical simulation method for the performance of recycled concrete as described in claim 1, characterized in that, The step of identifying the ITZ region of the polygonal microstructure based on the average thickness of the old ITZ includes: Retrieve the recycled concrete corresponding to the polygonal microstructure; The internal three-dimensional structure of the recycled concrete was obtained, and the mechanical properties of the recycled concrete were measured. Simultaneously, microscopic morphological images of the recycled concrete were acquired. Based on the microscopic morphology image, the aggregate-mortar interface of the recycled concrete is identified, and the gray-level co-occurrence matrix of the aggregate-mortar interface is calculated. Based on the gray-level co-occurrence matrix, the interface texture features of the recycled concrete are extracted; The density distribution characteristics of the recycled concrete are extracted from the internal three-dimensional structure, and the modulus gradient characteristics of the recycled concrete are identified based on the mechanical properties. By combining the average thickness of the old ITZ, the interface texture features, the density distribution features, and the modulus gradient features, the ITZ region of the polygonal microstructure is identified.

5. The numerical simulation method for the performance of recycled concrete as described in claim 1, characterized in that, The identification of initial damage points of the polygonal microstructure from the stress concentration region and the ITZ region includes: Calculate the normalized stress gradient between adjacent elements within the stress concentration region; The degree of degradation in the ITZ region is quantified to obtain the ITZ degradation degree; Calculate the percentage of microcracks per unit area within the ITZ region; Based on the normalized stress gradient, the ITZ degradation degree, and the proportion of microcracks, a damage accumulation index for the polygonal mesostructure is constructed. Set a damage threshold for the damage accumulation index, and use the damage threshold to determine the potential damage initiation region of the polygonal mesostructure; Damage initiation seed points of the polygonal mesostructure are identified from the potential damage initiation region; Abnormal points are identified from the damage initiation seed point, and the abnormal points are removed to obtain the initial damage points of the polygonal microstructure.

6. The numerical simulation method for the performance of recycled concrete as described in claim 1, characterized in that, The method of setting the damage initiation position determiner for the polygonal mesostructure using the initial damage point includes: Extract the new ITZ region and the old ITZ region corresponding to the polygonal mesoscopic architecture; Based on the initial damage point, identify the local stress field and microcrack layout corresponding to the new ITZ region and the old ITZ region; Identify the initial damage point coordinate set corresponding to the initial damage point to construct the damage point spacing matrix of the polygonal mesostructure; The stress concentration degree corresponding to the new ITZ region and the old ITZ region was measured respectively, and the performance degradation rate corresponding to the new ITZ region and the old ITZ region was analyzed based on the microcrack layout. Based on the damage point spacing matrix, the stress concentration degree, and the performance degradation rate, the damage feature vector of the polygonal mesostructure is extracted. Based on the damage feature vector, a damage determination rule for the polygonal mesoscopic architecture is constructed. Based on the damage determination rule, an adaptive threshold is set for the polygonal mesostructure; Based on the adaptive threshold and the initial set of damage point coordinates, a damage propagation network for the polygonal mesoscopic architecture is generated. Based on the damage transmission network, a dual-mode damage verification mechanism is set for the polygonal mesoscopic architecture; Based on the damage transmission network and the dual-mode damage verification mechanism, a damage initiation location determiner for the polygonal mesoscopic architecture is set.

7. The numerical simulation method for the performance of recycled concrete as described in claim 1, characterized in that, The step of tracing the expansion trajectory of the initial expansion path in the polygonal mesostructure based on the initial damage point includes: Based on the initial damage point, mark the new-old ITZ stress concentration areas of the polygonal mesostructure; Construct a dual-channel analysis unit for the initial extension path in the new-old ITZ stress concentration zone, and configure the real-time tracking node of the dual-channel analysis unit; Based on the dual-channel analysis unit and the real-time tracking node, the trajectory topology network of the polygonal mesoscopic architecture is set; Based on the trajectory topology network, a damage evolution monitor with the polygonal mesoscopic architecture is configured; The damage evolution monitor is used to track the expansion trajectory of the initial expansion path in the polygonal microstructure.

8. The numerical simulation method for the performance of recycled concrete as described in claim 1, characterized in that, The step of setting the five-phase constitutive relationship of the polygonal mesostructure based on the old mortar adhesion rate and the average thickness of the old ITZ includes: Based on the old mortar adhesion rate and the average thickness of the old ITZ, the material phase boundaries of the polygonal microstructure are identified. Based on the material phase boundaries, the five-phase material of the polygonal mesostructure is determined; Construct the stiffness transfer matrix of the five-phase material; Based on the stiffness transfer matrix, the stress distribution weights of the polygonal mesostructure are set; Configure the multi-scale constitutive units of the polygonal mesoscopic architecture according to the stress allocation weights; The five-phase constitutive relation of the polygonal mesoscopic architecture is set through the multi-scale constitutive unit.

9. The numerical simulation method for the performance of recycled concrete as described in claim 1, characterized in that, The step of generating a damage cloud map of the polygonal mesoscopic architecture based on the damage variables includes: Based on the damage variables, a damage level threshold is set for the polygonal mesostructure; Based on the damage level threshold, identify the damage level regions of the polygonal mesostructure; Construct geometric mapping units corresponding to the damage level region; Based on the geometric mapping unit, the graphics generation rules for the polygonal microstructure are set; Configure the dynamic visualization engine for the polygonal microstructure based on the graphics generation rules; Based on the dynamic visualization engine, a damage cloud map of the polygonal microstructure is generated.

10. The numerical simulation method for the performance of recycled concrete as described in claim 1, characterized in that, The performance numerical simulation of the recycled concrete is performed by combining the damage cloud map, the expansion trajectory, the damage initiation location determiner, and the polygonal microstructure to obtain the performance numerical simulation results, including: Based on the aforementioned polygonal microstructure, the multi-scale material composition elements of the recycled concrete were analyzed. The mechanical properties of the constituent elements of the multi-scale material were analyzed; Based on the multi-scale material composition elements and the mechanical properties, the damage evolution characteristic parameters of the recycled concrete are set; The initial damage core area of ​​the recycled concrete is located using the damage initiation location determiner. Based on the aforementioned expansion trajectory, a multi-crack collaborative expansion network for the recycled concrete is constructed. Based on the damage cloud map, a damage distribution characterization system for the recycled concrete is created; By combining the damage evolution characteristic parameters, the initial damage core region, the multi-crack collaborative propagation network, and the damage distribution characterization system, a full-cycle performance evolution map of the recycled concrete is generated. Based on the full-cycle performance evolution map, the performance numerical simulation of the recycled concrete is performed to obtain the performance numerical simulation results.

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