Compressive strength testing method and system based on construction waste recycled aggregate

Abstract

The invention discloses a compressive strength testing method and system based on building waste recycled aggregate, and relates to the technical field of building material testing, and the method comprises the following steps: extracting multiple groups of samples from a to-be-tested building waste recycled aggregate pile according to a specific partition sampling strategy, and carrying out preliminary screening treatment on each group of samples; and mixing the screened samples according to a set proportion to prepare a standard test piece, wherein the size and the shape of the standard test piece are determined according to experimental requirements. Through a partition sampling strategy and a standardized test piece preparation process, the representativeness of sample selection is improved. Compared with a traditional testing method, the method has the advantages that the real compressive properties of recycled aggregates of different batches and sources can be reflected more comprehensively, and a reliable basis is provided for quality evaluation of the recycled aggregates. The spatial distribution characteristic that the samples cover the whole aggregate heap is ensured through a partition sampling strategy, and deviation caused by local sampling is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of building material testing, and in particular to a compressive strength testing method and system based on recycled aggregate from construction waste. Background Art

[0002] In recent years, with the rapid development of the construction industry, the amount of construction waste generated has continued to increase. Processing construction waste into recycled aggregate not only alleviates the shortage of natural aggregate resources but also effectively reduces environmental pressure. In the practical application of recycled aggregate, its compressive strength is a core indicator of quality. Accurate compressive strength testing is crucial for ensuring the safe use of recycled aggregate in construction projects. Currently, compressive strength testing of recycled aggregate from construction waste is typically performed using methods such as 7-day / 28-day unconfined compressive strength testing with standard specimens.

[0003] However, due to the complex composition of construction waste and the significant differences in the properties of recycled aggregate from different sources, existing testing methods have limitations in sample selection. Existing technologies do not adequately account for the complex characteristics of recycled aggregate, and the selected samples fail to fully reflect the overall properties of the recycled aggregate. This can lead to deviations in test results from the actual compressive strength of recycled aggregate from different batches and sources, thus affecting the accuracy of recycled aggregate quality assessments and their appropriate application in construction projects. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a compressive strength testing method and system based on recycled aggregates from construction waste, which is used to solve the problems in the existing technology that the sample selection process is not representative enough and the test results are difficult to accurately reflect the true compressive strength of recycled aggregates from different batches and sources.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A compressive strength testing method based on recycled aggregates from construction waste comprises the following steps:

[0006] Extract multiple groups of samples from the recycled aggregate pile of construction waste to be tested according to a specific zoning sampling strategy, and perform preliminary screening on each group of samples;

[0007] The sieved samples are mixed according to the set ratio to prepare standard specimens. The size and shape of the standard specimens are determined according to the experimental requirements.

[0008] Use a pressure loading device to apply gradually increasing pressure to the standard specimen and record the deformation data of the specimen at different pressure levels;

[0009] Based on the collected deformation data and the geometric characteristics of the specimen, the compressive strength value is calculated;

[0010] By statistically analyzing the compressive strength values ​​of multiple specimens, a compressive strength distribution curve is generated to evaluate the overall compressive performance of recycled aggregate.

[0011] Furthermore, extracting multiple groups of samples from the pile of recycled aggregate from construction waste to be tested according to a specific partition sampling strategy includes the following steps:

[0012] The recycled aggregate pile to be tested is divided into three-dimensional grids, and the volume of each grid unit is a fixed value;

[0013] Several sampling points are randomly selected in each grid cell, and the number of sampling points is related to the aggregate density in the grid cell;

[0014] The samples extracted from all sampling points are combined into one group of samples, and the above steps are repeated until a preset number of sample groups are obtained.

[0015] Furthermore, the preparation of a standard test piece by mixing the sieved samples according to a set ratio includes the following steps:

[0016] Each group of samples was subjected to particle size classification and divided into three categories: coarse aggregate, medium aggregate and fine aggregate;

[0017] According to the proportion requirements of the experimental design, the coarse aggregate, medium aggregate and fine aggregate are mixed evenly according to the mass ratio;

[0018] Mix the aggregate and cement paste evenly according to the set ratio, fill them into the mold and vibrate them to make them dense;

[0019] The filled mold is placed in a constant temperature and humidity environment and cured to the specified age to form a standard test piece.

[0020] Furthermore, applying gradually increasing pressure to the standard specimen using the pressure loading device comprises the following steps:

[0021] Place the standard specimen on the workbench of the pressure loading device and adjust the position of the specimen so that its axis coincides with the loading direction;

[0022] Start the pressure loading device and apply pressure at a set loading rate between 0.1 MPa / s and 1 MPa / s;

[0023] During the loading process, the strain data on the specimen surface and the pressure data at the loading end are collected in real time;

[0024] When the specimen shows obvious damage or the loading pressure reaches the preset upper limit, the loading process is stopped.

[0025] Furthermore, the calculation of the compressive strength value based on the collected deformation data and the geometric characteristics of the specimen includes the following steps:

[0026] Calculate the cross-sectional area of ​​the specimen based on its geometric dimensions;

[0027] The compressive strength value of the specimen is obtained by dividing the maximum pressure value recorded during the loading process by the cross-sectional area;

[0028] The compressive strength value is corrected, and the correction factor is determined by the material properties of the specimen and the loading conditions.

[0029] Furthermore, generating a compressive strength distribution curve by statistically analyzing the compressive strength values ​​of a plurality of test pieces includes the following steps:

[0030] Arrange the compressive strength values ​​of all specimens in ascending order and calculate the cumulative frequency corresponding to each strength value;

[0031] Draw a distribution curve with compressive strength value as the horizontal axis and cumulative frequency as the vertical axis;

[0032] The distribution curve is smoothed by fitting algorithm to obtain the probability density function of compressive strength;

[0033] The probability density function was used to calculate the average compressive strength value and standard deviation of recycled aggregate.

[0034] The present invention also provides a compressive strength testing system based on recycled aggregates from construction waste, comprising the following modules:

[0035] The sampling module is configured to extract multiple groups of samples from the pile of recycled aggregates of construction waste to be tested according to a specific partition sampling strategy, and perform preliminary screening processing on each group of samples;

[0036] The specimen preparation module is configured to mix the sieved samples according to a set ratio and prepare a standard specimen;

[0037] A pressure loading module is configured to apply gradually increasing pressure to the standard specimen using a pressure loading device, and record deformation data of the specimen under different pressure levels;

[0038] a data analysis module configured to calculate the compressive strength value of the specimen based on the collected deformation data and in combination with the geometric characteristics of the specimen, and generate a compressive strength distribution curve by performing statistical analysis on the compressive strength values ​​of multiple specimens;

[0039] The main control module is connected to the sampling module, the specimen preparation module, the pressure loading module and the data analysis module, and is used to execute the compressive strength testing method based on recycled aggregate from construction waste as described in any one of claims 1 to 6.

[0040] Furthermore, the sampling module includes a three-dimensional grid division unit for performing three-dimensional grid division on the recycled aggregate pile to be tested, and the volume of each grid unit is a fixed value.

[0041] Furthermore, the specimen preparation module includes a particle size grading unit, which is used to classify each group of samples into three categories according to particle size: coarse aggregate, medium aggregate and fine aggregate, where the particle size of coarse aggregate is greater than 10 mm, the particle size of medium aggregate is between 5 mm and 10 mm, and the particle size of fine aggregate is less than 5 mm.

[0042] Furthermore, the pressure loading module includes a loading rate control unit for applying pressure at a set loading rate, and the loading rate is between 0.1 MPa / s and 1 MPa / s.

[0043] Beneficial effects

[0044] The present invention improves the representativeness of sample selection through a zoning sampling strategy and a standardized specimen preparation process. Compared with traditional testing methods, the present invention can more comprehensively reflect the true compressive performance of recycled aggregates from different batches and sources, providing a reliable basis for the quality assessment of recycled aggregates. The zoning sampling strategy ensures that the samples cover the spatial distribution characteristics of the entire aggregate pile, avoiding the deviation caused by local sampling. At the same time, the present invention adopts a standardized specimen preparation process and precise pressure loading control to make the compressive strength test results more accurate and stable. In addition, the compressive strength distribution curve is generated through statistical analysis, which further improves the scientific nature and reference value of the test results, and provides technical support for the rational application of recycled aggregates in construction projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the method flow of the present invention;

[0046] Figure 2 Schematic diagram of the module structure of the system of the present invention. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] See also Figure 1 and Figure 2 The present invention provides a compressive strength testing method based on recycled aggregate from construction waste, comprising the following steps:

[0049] Extract multiple groups of samples from the recycled aggregate pile of construction waste to be tested according to a specific zoning sampling strategy, and perform preliminary screening on each group of samples;

[0050] The sieved samples are mixed according to the set ratio to prepare standard specimens. The size and shape of the standard specimens are determined according to the experimental requirements.

[0051] Use a pressure loading device to apply gradually increasing pressure to the standard specimen and record the deformation data of the specimen at different pressure levels;

[0052] Based on the collected deformation data and the geometric characteristics of the specimen, the compressive strength value is calculated;

[0053] By statistically analyzing the compressive strength values ​​of multiple specimens, a compressive strength distribution curve is generated to evaluate the overall compressive performance of recycled aggregate.

[0054] As a preferred implementation of this embodiment, extracting multiple groups of samples from the pile of recycled aggregates from construction waste to be tested according to a specific partition sampling strategy includes the following steps:

[0055] The recycled aggregate pile to be tested is divided into three-dimensional grids, and the volume of each grid unit is a fixed value;

[0056] Several sampling points are randomly selected in each grid cell, and the number of sampling points is related to the aggregate density in the grid cell;

[0057] The samples extracted from all sampling points are combined into one group of samples, and the above steps are repeated until a preset number of sample groups are obtained.

[0058] As a preferred implementation of this embodiment, the preparation of a standard test piece by mixing the sieved samples according to a set ratio includes the following steps:

[0059] Each group of samples was subjected to particle size classification and divided into three categories: coarse aggregate, medium aggregate and fine aggregate;

[0060] According to the proportion requirements of the experimental design, the coarse aggregate, medium aggregate and fine aggregate are mixed evenly according to the mass ratio;

[0061] Mix the aggregate and cement paste evenly according to the set ratio, fill them into the mold and vibrate them to make them dense;

[0062] The filled mold is placed in a constant temperature and humidity environment and cured to the specified age to form a standard test piece.

[0063] As a preferred implementation of this embodiment, applying gradually increasing pressure to the standard specimen using the pressure loading device includes the following steps:

[0064] Place the standard specimen on the workbench of the pressure loading device and adjust the position of the specimen so that its axis coincides with the loading direction;

[0065] Start the pressure loading device and apply pressure at a set loading rate between 0.1 MPa / s and 1 MPa / s;

[0066] During the loading process, the strain data on the specimen surface and the pressure data at the loading end are collected in real time;

[0067] When the specimen shows obvious damage or the loading pressure reaches the preset upper limit, the loading process is stopped.

[0068] As a preferred implementation of this embodiment, the calculation of the compressive strength value based on the collected deformation data and the geometric characteristics of the specimen includes the following steps:

[0069] Calculate the cross-sectional area of ​​the specimen based on its geometric dimensions;

[0070] The compressive strength value of the specimen is obtained by dividing the maximum pressure value recorded during the loading process by the cross-sectional area;

[0071] The compressive strength value is corrected, and the correction factor is determined by the material properties of the specimen and the loading conditions.

[0072] As a preferred implementation of this embodiment, generating a compressive strength distribution curve by statistically analyzing the compressive strength values ​​of multiple specimens includes the following steps:

[0073] Arrange the compressive strength values ​​of all specimens in ascending order and calculate the cumulative frequency corresponding to each strength value;

[0074] Draw a distribution curve with compressive strength value as the horizontal axis and cumulative frequency as the vertical axis;

[0075] The distribution curve is smoothed by fitting algorithm to obtain the probability density function of compressive strength;

[0076] The probability density function was used to calculate the average compressive strength value and standard deviation of recycled aggregate.

[0077] The present invention also provides a compressive strength testing system based on recycled aggregates from construction waste, comprising the following modules:

[0078] The sampling module is configured to extract multiple groups of samples from the pile of recycled aggregates of construction waste to be tested according to a specific partition sampling strategy, and perform preliminary screening processing on each group of samples;

[0079] The specimen preparation module is configured to mix the sieved samples according to a set ratio and prepare a standard specimen;

[0080] A pressure loading module is configured to apply gradually increasing pressure to the standard specimen using a pressure loading device, and record deformation data of the specimen under different pressure levels;

[0081] a data analysis module configured to calculate the compressive strength value of the specimen based on the collected deformation data and in combination with the geometric characteristics of the specimen, and generate a compressive strength distribution curve by performing statistical analysis on the compressive strength values ​​of multiple specimens;

[0082] The main control module is connected to the sampling module, the specimen preparation module, the pressure loading module and the data analysis module, and is used to execute the compressive strength testing method based on recycled aggregate from construction waste as described in any one of claims 1 to 6.

[0083] As a preferred implementation of this embodiment, the sampling module includes a three-dimensional grid division unit for performing three-dimensional grid division on the recycled aggregate pile to be tested, and the volume of each grid unit is a fixed value.

[0084] As a preferred implementation of this embodiment, the specimen preparation module includes a particle size grading unit, which is used to divide each group of samples into three categories according to particle size: coarse aggregate, medium aggregate and fine aggregate, where the particle size of coarse aggregate is greater than 10 mm, the particle size of medium aggregate is between 5 mm and 10 mm, and the particle size of fine aggregate is less than 5 mm.

[0085] As a preferred implementation of this embodiment, the pressure loading module includes a loading rate control unit for applying pressure at a set loading rate, and the loading rate is between 0.1 MPa / s and 1 MPa / s.

[0086] The following is combined with Figure 1 and attached Figure 2 Specific embodiments of the present invention are described in detail.

[0087] In practical applications, the testing method and system of the present invention primarily consist of five modules: a sampling module, a specimen preparation module, a pressure loading module, a data analysis module, and a main control module. These modules work together through a combination of logical and physical connections to complete the overall process from sample collection to compressive strength distribution curve generation.

[0088] During the implementation process, the sampling module first samples the recycled aggregate from the construction waste pile to be tested in different zones. The sampled aggregate is then transferred to the specimen preparation module for screening and mixing, ultimately forming a standard specimen. Once the specimen is prepared, it is transferred to the pressure loading module for compressive strength testing. The deformation and pressure data generated during the test are transmitted in real time to the data analysis module for processing, ultimately generating a compressive strength distribution curve. The entire process is coordinated and managed by the main control module.

[0089] (1) Specific operations of the sampling module

[0090] The core function of the sampling module is to ensure the representativeness and uniformity of sample selection. In actual operation, the sampling module first divides the recycled aggregate pile of construction waste to be tested into a three-dimensional grid. The volume of each grid unit is determined according to the total volume of the aggregate pile and the number of preset sample groups (for example, when the total volume is 100 cubic meters and 10 groups of samples are preset, the volume of a single grid unit is 10 cubic meters). This ensures that the grid division covers the entire aggregate pile and there are no duplicate areas. This division method can effectively cover the spatial distribution characteristics of the entire aggregate pile and avoid deviations caused by local sampling.

[0091] In each grid unit, the sampling module randomly selects a number of sampling points according to the aggregate density. The number of sampling points is linearly positively correlated with the aggregate density in the grid unit. The calculation formula is: n = k × ρ, where n is the number of sampling points (take an integer), and ρ is the aggregate density in the grid unit (unit: kg / m 3 ), k is the proportional coefficient (usually 0.001, that is, every 1000kg of aggregate corresponds to 1 sampling point). For example, when the aggregate density is 1500kg / m 3 In the grid unit, the number of sampling points is 1500×0.001=1.5≈2; in the case of a density of 800kg / m 3 For an area with a sampling point of 1, the number of sampling points is 1.

[0092] The samples collected at all sampling points are combined into one sample group, and the above steps are repeated until a predetermined number of sample groups are obtained (usually each sample group weighs at least 5 kg, and the number of sample groups is at least 3). The output of the sampling module is connected to the input of the specimen preparation module. After sampling is completed, the samples directly enter the specimen preparation module for subsequent processing.

[0093] (2) Specific operations of the specimen preparation module

[0094] The main task of the specimen preparation module is to perform preliminary screening and standardization of the samples provided by the sampling module. During the screening process, the specimen preparation module divides each group of samples into three categories according to particle size: coarse aggregate, medium aggregate and fine aggregate. The classification is based on the particle size range of the aggregate, where the particle size of the coarse aggregate is greater than 10 mm, the particle size of the medium aggregate is between 5 mm and 10 mm, and the particle size of the fine aggregate is less than 5 mm. After the screening is completed, the specimen preparation module mixes the aggregate according to the proportion requirements of the experimental design. The mixing ratio needs to be determined based on the application scenario of the recycled aggregate: when used for concrete structural components, coarse aggregate: medium aggregate: fine aggregate = 6:3:1 (mass ratio), which simulates the aggregate grading in structural concrete; when used for non-load-bearing wall materials, the ratio is adjusted to 4:3:3 to improve the integrity of the material. The mixed aggregate and cement paste are stirred evenly according to the set ratio. The mass ratio of aggregate to cement paste is 4:1 (cement: water: admixture = 1:0.5:0.2, ensuring that the paste fluidity meets the filling requirements).

[0095] After mixing is complete, the specimen preparation module fills the mixture into a mold (common molds are 150mm×150mm×150mm cubes or φ100mm×200mm cylinders, selected according to the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete") and compacts it by vibration (vibration frequency 50Hz, duration 30 seconds) to ensure that no bubbles remain inside the specimen. The filled mold is placed in a constant temperature and humidity environment for curing (temperature 20±2℃, relative humidity ≥95%) to the specified age (curing for 7 days for short-term evaluation and curing for 28 days for final quality acceptance) to form a standard specimen that meets the experimental requirements. The output of the specimen preparation module is connected to the input of the pressure loading module. After the standard specimen is prepared, it directly enters the pressure loading module for compressive strength testing.

[0096] (3) Specific operation of pressure loading module

[0097] The pressure-loading module is a key component in the system used to perform compressive strength testing. In practice, it first places a standard specimen on a workbench and uses an adjustment mechanism (calibrated with a laser positioner, with a deviation of ≤0.5°) to ensure that the specimen's axis is perfectly aligned with the loading direction, minimizing eccentricity during loading.

[0098] After the adjustment is completed, the pressure loading module starts the loading device. The loading rate is selected according to the aggregate particle size distribution: when the coarse aggregate accounts for more than 50%, the rate is 0.3MPa / s; when the medium aggregate accounts for more than 50%, the rate is 0.5MPa / s; when the fine aggregate accounts for more than 50%, the rate is 0.8MPa / s (the rate range is 0.1MPa / s to 1MPa / s, which meets the requirements of the "Test Method for Recycled Aggregates for Construction"). During the loading process, the pressure loading module collects real-time strain data on the specimen surface and pressure data on the loading end through strain sensors (accuracy of ±2με) and pressure sensors (accuracy of ±0.5%FS), with a sampling frequency of 10Hz.

[0099] The pressure loading module automatically stops loading when the specimen shows significant damage (strain spike > 500 με) or when the loading pressure reaches a preset upper limit (typically 1.5 times the design strength). The collected deformation and pressure data are transmitted to the data analysis module via a USB 3.0 data transmission interface for further processing. The output of the pressure loading module is connected to the input of the data analysis module to ensure real-time and accurate data transmission.

[0100] (IV) Specific operations of the data analysis module

[0101] The data analysis module is responsible for processing and analyzing the data transmitted by the pressure loading module to calculate the compressive strength value of the specimen and generate a compressive strength distribution curve.

[0102] 1. Compressive strength calculation

[0103] First, calculate the cross-sectional area of ​​the specimen based on its geometric dimensions:

[0104] -Cube specimen: A = a 2 (a is the side length, unit is mm)

[0105] -Cylindrical specimen: A = π × (d / 2) 2 (d is the diameter, unit is mm)

[0106] Then, the maximum pressure value (F max , in N) divided by the cross-sectional area (A, in mm 2 ), and the initial compressive strength value is obtained:

[0107]

[0108] The compressive strength value is corrected. The correction factor (k) is determined by the material properties of the specimen and the loading conditions:

[0109] k=1+0.01×(P-0.5)+0.02×(S-20)

[0110] Where P is the proportion of coarse aggregate (decimal), and S is the curing age (days). The ultimate compressive strength is:

[0111] f cu =f cu,0 ×k

[0112] 2. Statistical analysis and distribution curve generation

[0113] The compressive strength values ​​(f cu,i ) are arranged in ascending order and the cumulative frequency (F i =i / (n+1), where n is the total number of specimens. A distribution curve is drawn with the compressive strength value as the horizontal axis and the cumulative frequency as the vertical axis.

[0114] The curve is smoothed by the normal distribution fitting algorithm (the mean μ and standard deviation σ are estimated by the least squares method) to obtain the probability density function of the compressive strength:

[0115]

[0116] The probability density function is used to calculate the average compressive strength (μ) and standard deviation (σ) of recycled aggregate, providing a scientific basis for subsequent quality assessment. The output of the data analysis module is connected to the input of the main control module, and the analysis results are summarized and displayed by the main control module.

[0117] (V) Specific operations of the main control module

[0118] The main control module is the core control unit of the system of the present invention, responsible for coordinating the operation of each module. Set parameters through the touch screen or computer software (supports Windows 10 system):

[0119] - Sampling module: grid volume, number of sample groups, density-sampling point correlation coefficient;

[0120] -Specimen preparation module: aggregate ratio, curing age, mold type;

[0121] -Pressure loading module: loading rate, stop conditions, sensor calibration parameters;

[0122] -Data analysis module: fitting algorithm type, confidence interval (default 95%).

[0123] The main control module displays the operating status of each module (sampling progress, curing time, loading curve) in real time. After the test is completed, a report is automatically generated, including the average compressive strength, standard deviation, distribution curve and original data records.

[0124] It can be seen from the above specific embodiments that the testing method and system of the present invention achieve a comprehensive evaluation of the compressive properties of recycled aggregates from construction waste through a partitioned sampling strategy, a standardized specimen preparation process, and precise pressure loading control. The partitioned sampling strategy ensures that the sample covers the spatial distribution characteristics of the entire aggregate pile, avoiding the deviation caused by local sampling. The standardized specimen preparation process enables the specimen to truly reflect the actual use status of the recycled aggregate through strict particle size classification and mixing ratio control. Precise pressure loading control ensures the accuracy and stability of the test results through a gradually increasing loading method and real-time data acquisition. In addition, the compressive strength distribution curve is generated through statistical analysis, which further improves the scientific nature and reference value of the test results and provides technical support for the rational application of recycled aggregates in construction projects.

[0125] In order to better enable relevant personnel in this technical field to fully understand and implement the present invention, the specific implementation principle of the present invention is supplemented below with reference to a specific application scenario.

[0126] At a construction waste treatment plant, technicians needed to comprehensively evaluate the compressive strength of a batch of recycled aggregate. This aggregate, sourced from multiple demolition projects, had a complex composition and significantly varying properties. To ensure the test results accurately reflected the characteristics of the entire aggregate pile, the technicians decided to employ the compressive strength testing method and system provided by this invention.

[0127] First, the sampling module starts the partition sampling strategy. The technicians divide the recycled aggregate pile to be tested into multiple three-dimensional grid units, and the volume of each unit is set to 1 cubic meter. Then, the sampling module randomly selects several sampling points in each grid unit based on the aggregate density information. For example, in areas where aggregates are densely piled, the sampling module detects a higher aggregate density through sensors, so the number of sampling points in this area is increased; in areas where aggregates are sparsely distributed, the number of sampling points is appropriately reduced. The samples extracted at all sampling points are merged into a group of samples, and the above steps are repeated until a preset number of sample groups are obtained. In this way, the sampling module ensures the uniformity of the spatial distribution of samples and avoids deviations caused by local sampling.

[0128] Next, the specimen preparation module performs preliminary screening and standardization on the received samples. The technicians divide each group of samples into three categories according to the particle size: coarse aggregate, medium aggregate and fine aggregate. The particle size of coarse aggregate is greater than 10 mm, the particle size of medium aggregate is between 5 mm and 10 mm, and the particle size of fine aggregate is less than 5 mm. After the screening is completed, the specimen preparation module mixes the coarse aggregate, medium aggregate and fine aggregate in a mass ratio of 6:3:1 according to the proportion requirements of the experimental design. Subsequently, the mixed aggregate and cement slurry are stirred evenly in a mass ratio of 4:1. The technicians fill the stirred mixture into the mold and compact it by vibration to eliminate internal bubbles. The filled mold is placed in a constant temperature and humidity environment for curing for 28 days to form a standard specimen that meets the experimental requirements.

[0129] When the standard specimen is prepared, the pressure loading module begins to test its compressive strength. The technician places the specimen on the workbench of the pressure loading device and adjusts the position of the specimen through a mechanical positioning device so that its axis completely coincides with the loading direction. This adjustment process minimizes the eccentricity error that may occur during the loading process. Subsequently, the pressure loading module applies pressure at a loading rate of 0.5 MPa / s, and collects the deformation data of the specimen surface and the pressure data of the loading end in real time through strain sensors and pressure sensors. When the specimen is obviously damaged or the loading pressure reaches the preset upper limit, the pressure loading module automatically stops the loading process. The collected data is transmitted to the data analysis module through the data transmission interface for further processing.

[0130] After receiving the deformation and pressure data, the data analysis module first calculates the cross-sectional area of ​​the specimen based on its geometric dimensions. For example, for a cylindrical specimen with a diameter of 100 mm and a height of 200 mm, its cross-sectional area is 7854 square millimeters. The data analysis module then divides the maximum pressure value recorded during loading by the cross-sectional area to obtain the specimen's compressive strength. To improve the accuracy of the calculation results, the data analysis module introduces a correction factor, which is determined by the specimen's material properties and loading conditions. For example, for specimens with a high proportion of fine aggregate, the correction factor is slightly lower than for specimens with a high proportion of coarse aggregate. After the calculation is complete, the data analysis module arranges the compressive strength values ​​of all specimens in ascending order and calculates the cumulative frequency corresponding to each strength value. A distribution curve is plotted with the compressive strength value as the horizontal axis and the cumulative frequency as the vertical axis. To improve the smoothness of the distribution curve, the data analysis module uses a fitting algorithm to process the curve, ultimately obtaining the probability density function of the compressive strength. Using the probability density function, the data analysis module calculated that the average compressive strength of the recycled aggregate is 35 MPa with a standard deviation of 5 MPa.

[0131] The entire test process is coordinated and managed by the main control module. The main control module first receives the partition sampling strategy parameters from the sampling module, and generates sampling instructions based on the preset sampling quantity and aggregate density information. After sampling is completed, the main control module sends screening and mixing instructions to the specimen preparation module to ensure that the specimen preparation process is strictly carried out in accordance with the experimental design. After the specimen preparation is completed, the main control module sends parameters such as loading rate and loading upper limit to the pressure loading module, and monitors the data collection during the loading process in real time. When the pressure loading module completes the test, the main control module transmits the collected data to the data analysis module, and generates a compressive strength distribution curve based on the processing results of the data analysis module. Finally, the main control module displays the test results to the user through the human-computer interaction interface.

[0132] Through the above-mentioned specific application scenarios, it can be seen that the testing method and system of the present invention realize a comprehensive evaluation of the compressive performance of recycled aggregates from construction waste through a partitioned sampling strategy, a standardized specimen preparation process, and precise pressure loading control. The partitioned sampling strategy ensures that the sample covers the spatial distribution characteristics of the entire aggregate pile, avoiding the deviation caused by local sampling. The standardized specimen preparation process enables the specimen to truly reflect the actual use status of the recycled aggregate through strict particle size classification and mixing ratio control. Precise pressure loading control ensures the accuracy and stability of the test results through a gradually increasing loading method and real-time data acquisition. In addition, the compressive strength distribution curve is generated through statistical analysis, which further improves the scientific nature and reference value of the test results, and provides technical support for the rational application of recycled aggregates in construction projects.

[0133] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0134] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A compressive strength test method based on recycled aggregates from construction waste, characterized in that: The following steps are involved: Extract multiple groups of samples from the recycled aggregate pile of construction waste to be tested according to a specific zoning sampling strategy, and perform preliminary screening on each group of samples; The sieved samples are mixed according to the set ratio to prepare standard specimens. The size and shape of the standard specimens are determined according to the experimental requirements. Use the pressure loading device to apply gradually increasing pressure to the standard specimen and record the deformation data of the specimen under different pressure levels; Based on the collected deformation data and the geometric characteristics of the specimen, the compressive strength value is calculated; By statistically analyzing the compressive strength values ​​of multiple specimens, a compressive strength distribution curve is generated to evaluate the overall compressive performance of recycled aggregate.

2. The compressive strength testing method based on recycled aggregate from construction waste according to claim 1, characterized in that: The method of extracting multiple groups of samples from the pile of recycled aggregates from construction waste to be tested according to a specific partition sampling strategy comprises the following steps: The recycled aggregate pile to be tested is divided into three-dimensional grids, and the volume of each grid unit is a fixed value; Several sampling points are randomly selected in each grid cell, and the number of sampling points is related to the aggregate density in the grid cell; The samples extracted from all sampling points are combined into one group of samples, and the above steps are repeated until a preset number of sample groups are obtained.

3. The compressive strength testing method based on recycled aggregate from construction waste according to claim 1, characterized in that: The preparation of the standard test piece by mixing the sieved samples according to a set ratio comprises the following steps: Each group of samples was subjected to particle size classification and divided into three categories: coarse aggregate, medium aggregate and fine aggregate; According to the proportion requirements of the experimental design, the coarse aggregate, medium aggregate and fine aggregate are mixed evenly according to the mass ratio; Mix the aggregate and cement paste evenly according to the set ratio, fill them into the mold and vibrate them to make them dense; The filled mold is placed in a constant temperature and humidity environment and cured to the specified age to form a standard test piece.

4. The compressive strength testing method based on recycled aggregate from construction waste according to claim 1, characterized in that: The step of applying gradually increasing pressure to the standard specimen by using the pressure loading device comprises the following steps: Place the standard specimen on the workbench of the pressure loading device and adjust the position of the specimen so that its axis coincides with the loading direction; Start the pressure loading device and apply pressure at a set loading rate between 0.1 MPa / s and 1 MPa / s; During the loading process, the strain data on the specimen surface and the pressure data at the loading end are collected in real time; When the specimen shows obvious damage or the loading pressure reaches the preset upper limit, the loading process is stopped.

5. The compressive strength testing method based on recycled aggregate from construction waste according to claim 1, characterized in that: The method of calculating the compressive strength value of the specimen based on the collected deformation data and the geometric characteristics of the specimen includes the following steps: Calculate the cross-sectional area of ​​the specimen based on its geometric dimensions; The compressive strength value of the specimen is obtained by dividing the maximum pressure value recorded during the loading process by the cross-sectional area; The compressive strength value is corrected, and the correction factor is determined by the material properties of the specimen and the loading conditions.

6. The compressive strength testing method based on recycled aggregate from construction waste according to claim 1, characterized in that: Generating a compressive strength distribution curve by statistically analyzing the compressive strength values ​​of a plurality of test pieces comprises the following steps: Arrange the compressive strength values ​​of all specimens in ascending order and calculate the cumulative frequency corresponding to each strength value; Draw a distribution curve with compressive strength value as the horizontal axis and cumulative frequency as the vertical axis; The distribution curve is smoothed by fitting algorithm to obtain the probability density function of compressive strength; The probability density function was used to calculate the average compressive strength value and standard deviation of recycled aggregate.

7. The compressive strength testing system based on recycled aggregate from construction waste is characterized by: Includes the following modules: The sampling module is configured to extract multiple groups of samples from the pile of recycled aggregates of construction waste to be tested according to a specific partition sampling strategy, and perform preliminary screening processing on each group of samples; The specimen preparation module is configured to mix the sieved samples according to a set ratio and prepare a standard specimen; A pressure loading module is configured to apply gradually increasing pressure to the standard specimen using a pressure loading device, and record deformation data of the specimen under different pressure levels; a data analysis module configured to calculate the compressive strength value of the specimen based on the collected deformation data and in combination with the geometric characteristics of the specimen, and generate a compressive strength distribution curve by performing statistical analysis on the compressive strength values ​​of multiple specimens; The main control module is connected to the sampling module, the specimen preparation module, the pressure loading module and the data analysis module, and is used to execute the compressive strength testing method based on recycled aggregate from construction waste as described in any one of claims 1 to 6.

8. The compressive strength testing system based on recycled aggregate from construction waste according to claim 7, characterized in that: The sampling module includes a three-dimensional grid division unit, which is used to perform three-dimensional grid division on the recycled aggregate pile to be tested, and the volume of each grid unit is a fixed value.

9. The compressive strength testing system based on recycled aggregate from construction waste according to claim 7, characterized in that: The specimen preparation module includes a particle size classification unit, which is used to classify each group of samples into three categories according to particle size: coarse aggregate, medium aggregate and fine aggregate. The particle size of coarse aggregate is greater than 10 mm, the particle size of medium aggregate is between 5 mm and 10 mm, and the particle size of fine aggregate is less than 5 mm.

10. The compressive strength testing system based on recycled aggregate from construction waste according to claim 7, characterized in that: The pressure loading module includes a loading rate control unit for applying pressure at a set loading rate, and the loading rate is between 0.1 MPa / s and 1 MPa / s.

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