Device and method for testing volume stability of concrete in gobi desert erosion environment based on DIC technology

Abstract

The invention relates to a testing device and a testing method for the volume stability of concrete in a gobi desert erosion environment based on a DIC technology, and belongs to the technical field of concrete performance detection. In order to solve the problem that the concrete performance in the severe environment of the gobi desert cannot be detected at present, an erosion environment simulation system, a DIC image acquisition system and an image data analysis and calculation system are arranged, and the erosion environment simulation system comprises an environment simulation box and an equipment control box; the DIC image acquisition system comprises an electric slide rail, a CCD (Charge Coupled Device) industrial camera, an industrial lens and a data transmission line and is used for performing image acquisition on the concrete test piece, and the image data analysis and calculation system is used for processing image information transmitted by the CCD industrial camera and calculating the volume stability of the concrete test piece. According to the invention, the whole-process detection of the concrete volume stability change in the gobi desert erosion environment can be realized, the equipment operation is simple, and theoretical basis and data support are provided for the research and application of the concrete performance in the harsh environment.

Description

Technical Field

[0001] The invention relates to the technical field of concrete performance testing, and in particular to a testing device and a testing method for the volume stability of concrete in a Gobi desert erosion environment based on DIC technology. Background Art

[0002] There are vast Gobi Desert environments in western my country, which have special climatic conditions, large temperature differences between day and night, high surface evaporation, strong winds and sand, and a large amount of high-concentration chlorides and sulfates and other corrosive salts in the soil, which will cause serious corrosion to bridges, roads and buildings, reduce their volume stability and shorten their service life. In order to study the specific characteristics of the Gobi Desert environment, the erosion environment of the Gobi Desert is usually simulated indoors, and the volume stability of concrete is continuously tested in this environment, so as to improve the durability of concrete structures in the Gobi Desert area and extend their service life in the Gobi Desert environment as much as possible.

[0003] At present, the determination method of concrete volume stability mainly uses displacement sensors, extensometers and foil resistance strain gauges and other measuring devices, but the above devices can only measure the concrete strain and displacement within the gauge range, and it is difficult to achieve point-by-point measurement of the entire concrete damage process. In addition, the simulation environment of indoor corrosion tests is relatively harsh, and conventional measuring devices such as strain gauges and displacement meters are easily affected by high temperature, low temperature and dry-wet cycle, resulting in a significant decrease in their measurement accuracy. Therefore, for indoor corrosion simulation tests, new test methods are needed to globally detect the performance of concrete specimens in corrosion environments.

[0004] Digital image correlation (DIC) technology is a non-contact, non-destructive deformation detection method that integrates digital image processing and numerical calculation. It can measure the deformation of concrete without affecting its early age development. It has the advantages of high sensitivity, high measurement accuracy, no special requirements for the environment, and simple equipment requirements. It does not require special optical instruments. At the same time, DIC technology has a wide measurement range and a high degree of automation. It can be used in concrete mechanical tests and performance detection. At present, some scholars have designed and studied concrete performance testing devices through DIC technology. For example, utility model patent CN220289459U discloses "A real-time low-temperature frost heave deformation test device based on three-dimensional DIC", invention patent CN116164690A discloses "A method and equipment for detecting carbonization depth of concrete based on DIC technology", and invention patent CN113466066B discloses "A method for measuring fatigue deformation and crack width of concrete materials based on DIC technology". The above-mentioned existing technologies do not involve the volume stability of concrete in the harsh environment of the complex Gobi Desert, and cannot realize the full process detection of concrete performance in an erosive environment, which affects the related research on non-destructive, rapid and continuous detection of concrete performance in the harsh environment of the Gobi Desert.

[0005] Based on this, it is necessary to propose a measurement device and method for the volume stability of concrete in the Gobi Desert erosion environment based on DIC technology, which can provide new ideas for the continuous detection of concrete volume stability under the coupling of multiple complex factors in the harsh environment of the Gobi Desert, and is of great significance for the global detection of concrete performance under indoor simulated Gobi Desert erosion simulation tests. Summary of the invention

[0006] In view of the defects existing in the above-mentioned prior art, the present invention aims to provide a testing device and a testing method for the volume stability of concrete in a Gobi Desert erosion environment based on DIC technology, which combines a Gobi Desert erosion environment simulation and control system, a mobile DIC image acquisition system, and a data analysis and calculation system into a whole. Based on the testing device and method, rapid, non-destructive and continuous detection of the volume stability of concrete in a Gobi Desert erosion environment can be achieved in a laboratory environment, and the change law of the volume stability of concrete in a Gobi Desert erosion environment can be studied, providing a basis for analyzing the performance degradation law of concrete in the harsh environment of the Gobi Desert.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The technical solution disclosed in the present invention is: a testing device for the volume stability of concrete in a Gobi Desert erosion environment based on DIC technology, comprising:

[0009] The erosion environment simulation system is used to place concrete specimens in it to simulate the erosion effect of the complex environment of the Gobi Desert on the concrete specimens;

[0010] A DIC image acquisition system, which is connected to the erosion environment simulation system and is used to obtain image data of the concrete specimen under the erosion environment simulation test;

[0011] The image data analysis and calculation system is connected to the DIC image acquisition system, and is used to receive the image data transmitted by the DIC image acquisition system, and calculate the volume stability of the concrete specimen at different erosion stages based on the image data.

[0012] As a further preferred embodiment of the above scheme: the erosion environment simulation system includes an environment simulation box, an anti-corrosion partition and an equipment control box arranged in sequence from bottom to top, wherein:

[0013] Equipment control box, used to control the simulated temperature and humidity in the environmental simulation box;

[0014] Anti-corrosion partition, connected between the environmental simulation box and the equipment control box;

[0015] The environmental simulation box is used to carry out Gobi desert erosion environment simulation tests on concrete specimens placed therein.

[0016] Based on the above technical solution, further, an electronic control panel is arranged on the outside of the equipment control box, and a water supply component, a heating component and a cooling component connected to the electronic control panel are arranged inside the equipment control box. The water supply component includes a water tank and a copper water pipe. The water tank is installed on the upper right side of the equipment control box. The copper water pipe is inserted in the water tank in an inverted U shape. The upper end of the copper water pipe extends into the environmental simulation box. The heating component and the cooling component are respectively connected to the copper water pipe. Temperature sensors are arranged on the heating component and the cooling component, and the temperature sensor is electrically connected to the electronic control panel. The operation of the water supply component, the heating component, the cooling component and the temperature sensor is adjusted and controlled by the electronic control panel.

[0017] Based on the above technical solution, further, corrosive wet sand and wipers are provided in the environmental simulation box, the concrete specimen is located in the environmental simulation box and inserted in the corrosive wet sand, the wiper is connected to the top of the environmental simulation box, a humidity sensor is buried in the corrosive wet sand, and the humidity sensor is electrically connected to the electronic control panel.

[0018] As a further preferred embodiment of the above scheme, the DIC image acquisition system includes an image acquisition box and an acquisition device component, and the acquisition device component includes:

[0019] An electric slide rail is installed on the inner top wall of the image acquisition box;

[0020] The electric slide rail controller is embedded in the electric slide rail;

[0021] The camera is movably connected to the electric slide rail via a slider;

[0022] The data transmission line comprises two parts, wherein two ends of the data transmission line of one part are respectively connected to the electric slide rail controller and the image data analysis and calculation system, and two ends of the data transmission line of the other part are respectively connected to the camera and the image data analysis and calculation system.

[0023] Based on the above technical solution, further, the camera includes a CCD industrial camera, an industrial lens and a polarized illumination light source, the CCD industrial camera is installed on an electric slide rail, the industrial lens is arranged at the bottom of the CCD industrial camera, and the polarized illumination light source is connected to the CCD industrial camera.

[0024] As a further preferred embodiment of the above scheme, the image data analysis and calculation system includes hardware and image processing software integrated on the hardware, wherein:

[0025] The hardware includes a trigger collector and a computer. The trigger collector is connected to the computer via a data cable and is used to transmit the image data collected by the camera to the computer.

[0026] The image processing software includes an image data preprocessing module, an image data analysis module and an image data storage and management module, which are respectively used to preprocess, analyze and store the image data received by the computer.

[0027] Another technical solution disclosed in the present invention is: a method for testing the volume stability of concrete in a Gobi Desert erosion environment based on DIC technology, the method testing the volume stability of concrete based on any of the above-mentioned testing devices, comprising the following steps:

[0028] S1 Establishment of indoor Gobi Desert erosion simulation environment: Use the equipment control box to adjust the erosion environment temperature and humidity, and set the time of different erosion stages;

[0029] S2 Preparation and pretreatment of concrete specimens: concrete specimens were prepared according to the simulated actual environment of the Gobi Desert, and speckle spraying was performed after standard curing;

[0030] S3 Equipment Installation: Lay out the water supply components, heating components and cooling components in the equipment control box, the eroded wet sand, concrete specimens and wipers in the environmental simulation box, and the electric slide rails, camera and data transmission lines in the image acquisition box, and then connect the image data analysis and calculation system with the DIC image acquisition system;

[0031] S4 Concrete specimen image data acquisition: take a surface image of a concrete specimen, then take surface images of the remaining concrete specimens when the electric slide rail is moving, and transmit and store the acquired surface images to the computer in real time;

[0032] S5 analyzes the volume stability of concrete specimens: the collected surface images are processed and corrected using image processing software, and then the visual image of the concrete specimen is output and exported as an image data file, and the volume stability of the concrete specimen is calculated through the image data file.

[0033] A further preferred embodiment of the above technical solution is as follows: in step S3, the steps of installing the water supply component, the heating component and the cooling component in the equipment control box include:

[0034] Place one end of the copper water pipe in the water tank;

[0035] The heating component and the cooling component are respectively arranged on both sides of the middle of the equipment control box;

[0036] After the installation is completed, the other end of the copper water pipe passes through the heating component, the cooling component and the corroded wet sand and then returns to the water tank to form a circulation loop.

[0037] Furthermore, in step S3, the steps of installing the corrosive wet sand, concrete specimen and wiper in the environmental simulation box include:

[0038] The concrete specimens were placed on stainless steel short columns in the environmental simulation box;

[0039] Lay eroded wet sand in the environmental simulation box. The thickness of the eroded wet sand is higher than the copper water pipe, and the eroded wet sand is kept flush with the surface of the concrete specimen.

[0040] burying a humidity sensor in the eroded wet sand and connecting the humidity sensor to an electronic control panel;

[0041] Install the wiper on the inner top wall of the environmental simulation box.

[0042] Compared with the prior art, the technical solution of the present invention achieves the following effects:

[0043] 1. The test device provided by the present invention can effectively simulate the real Gobi Desert erosion environment indoors, detect the dynamic changes of concrete during the erosion process in real time, and perform strain and displacement analysis on the surface of slow setting soil to comprehensively evaluate the stability of concrete. The DIC image acquisition system can be dynamically adjusted according to different test conditions, and is suitable for different test environments and volume stability analysis of different concretes and other materials.

[0044] 2. The test device provided by the present invention is convenient for experimenters to operate and maintain, reduces complex manual operations, and improves test efficiency; it collects a large amount of displacement and strain data, which is helpful for engineering design and structural optimization, and improves the reliability and durability of concrete buildings in extreme environments.

[0045] 3. The testing device provided by the present invention is simple to operate, economical and practical. The testing method can realize the analysis of the volume stability of concrete specimens under various corrosive environments, and can provide design ideas for the research and detection application of concrete performance in harsh environments. It has important engineering significance and broad application prospects.

[0046] 4. The test method provided by the present invention can display the deformation of concrete specimens during the entire erosion process, obtain the displacement cloud map and strain cloud map of concrete specimens in the Gobi Desert erosion environment, and fully understand the stress and deformation state of concrete; the volume stability measurement of the entire process is performed through a CCD industrial camera and image processing software, without contacting the concrete specimen, maintaining its integrity, and allowing repeated measurements of the same concrete specimen at different times and conditions, which is convenient for long-term detection and comparative analysis; the DIC software can automatically process and analyze image data, reduce human errors and workload, and provide rich statistical information and analysis results, with the advantages of high measurement accuracy, low detection damage, good data visualization effect, and fast data processing and analysis speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required in the embodiments are briefly introduced below.

[0048] Figure 1 It is a flowchart of the method for testing the volume stability of concrete in a Gobi Desert erosion environment based on the DIC technology of the present invention, and a schematic diagram of the testing device;

[0049] Figure 2 It is a schematic diagram of a device for testing the volume stability of concrete in a Gobi Desert erosion environment based on the DIC technology of the present invention;

[0050] Figure 3 The temperature change in Nukus area in 2022 in the test method of the present invention;

[0051] Figure 4 It is a structural schematic diagram of the control box of the Gobi Desert erosion environment equipment in the testing device of the present invention;

[0052] Figure 5 It is a schematic diagram of the structure of the Gobi Desert erosion environment simulation box in the testing device of the present invention;

[0053] Figure 6 It is a structural schematic diagram of a mobile DIC image acquisition box in the testing device of the present invention;

[0054] Figure 7 This is a flow chart of the DIC system construction and acquisition process in the testing method of the present invention;

[0055] Among them: 1- equipment control box; 2- environmental simulation box; 11- water tank; 12- centrifugal water pump; 13- heating rod; 14- compressor; 15- condenser; 16- expansion valve; 17- evaporator; 18- copper water pipe; 19- heat insulation baffle; 20- anti-corrosion baffle; 21- eroded wet sand; 22- concrete specimen; 23- stainless steel short column; 24- wiper; 25- glass observation window; 26- humidity sensor; 3- temperature sensor; 4- electronic control panel; 5- image acquisition box; 50- CCD industrial camera; 51- industrial lens; 52- polarized lighting source; 53- electric slide; 54- electric slide controller; 55- data transmission line; 56- slider; 6- image data analysis and calculation system; 60- trigger collector; 61- computer host; 62- computer accessories; 7- power cord; 8- power socket; 9- exhaust vent. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the embodiments will be described clearly and completely in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments, not all of the embodiments. For ordinary technicians in this field, other embodiments can be obtained without creative work.

[0057] Embodiment 1:

[0058] Reference Figure 1-7 The present invention proposes a testing device for the volume stability of concrete in a Gobi desert erosion environment based on DIC technology, including an erosion environment simulation system, a DIC image acquisition system and an image data analysis and calculation system 6. A concrete specimen 22 is provided in the erosion environment simulation system to simulate the erosion effect of the complex environment of the Gobi desert on the concrete specimen 22; the DIC image acquisition system is connected to the erosion environment simulation system and the image data analysis and calculation system respectively, and the image data of the concrete specimen 22 under the simulation test is obtained through the DIC image acquisition system, and the image data is transmitted to the image data analysis and calculation system 6, and then the volume stability of the concrete specimen 22 at different erosion stages is calculated based on the image data.

[0059] Specifically, the erosion environment simulation system includes an equipment control box 1, an environmental simulation box 2 and an anti-corrosion partition 20. The equipment control box 1 is placed at the bottom of the environmental simulation box 2. The simulated temperature and humidity in the environmental simulation box 2 are controlled by the equipment control box 1. The concrete specimen 22 placed in the environmental simulation box 2 is subjected to a Gobi desert erosion environment simulation test. The anti-corrosion partition 20 is arranged between the environmental simulation box 2 and the equipment control box 1. It is made of stainless steel and coated with an anti-corrosion coating on the surface. It is dustproof and waterproof. The anti-corrosion partition 20 is used to separate the equipment control box 1 from the environmental simulation box 2.

[0060] like Figure 2 , Figure 4 As shown, an electronic control panel 4 is arranged outside the device control box 1, an exhaust port 9 is opened on one side of the device control box 1, and a water supply component, a heating component and a cooling component connected to the electronic control panel 4 are arranged inside the device control box 1, the heating component and the cooling component are respectively connected to the water supply component, a temperature sensor 3 is arranged on the heating component and the cooling component, and the temperature sensor 3 is connected to the electronic control panel 4, and the operation of the water supply component, the heating component, the cooling component and the temperature sensor 3 is adjusted and controlled by the electronic control panel 4.

[0061] More specifically, the water supply component includes a water tank 11 and a copper water pipe 18. The water tank 11 is made of stainless steel and is used to store tap water and corrosive salt solution required for the test. The middle of the water tank 11 is connected to a heat-insulating baffle 19 to divide the water tank 11 into two parts, the left and right parts. The heating component and the cooling component are respectively located on both sides of the heat-insulating baffle 19, and the heating component and the cooling component are respectively wrapped on the outside of the copper water pipe 18 to adjust the water temperature in the copper water pipe 18 to the set temperature of the test. Both ends of the copper water pipe 18 are placed in the water tank 11. One end of the copper water pipe 18 extends upward to the environmental simulation box 2 after passing through the centrifugal water pump 12 and the heating component and the cooling component to control the temperature and humidity in the environmental simulation box 2. The other end of the copper water pipe 18 extends downward to the water tank 11 through the environmental simulation box 2 to form a circulation loop;

[0062] The heating assembly includes a heating rod 13, a temperature sensor 3 and a water flow channel. The heated hot water flows out from the water outlet of the water flow channel and enters the next part of the circulation loop. The temperature sensor 3 is used to detect the water temperature to ensure that the erosion environment simulation system operates within the set temperature range. Preferably, one end of the temperature sensor 3 connected to the heating assembly is respectively installed at the inlet and outlet of the heating rod 13 to measure the water temperature before and after heating to ensure that the set values ​​of the initial water temperature and the heating water temperature meet the test requirements. The other end of the temperature sensor 3 is electrically connected to the electronic control panel 4.

[0063] The cooling assembly includes a compressor 14, a condenser 15, an expansion valve 16 and an evaporator 17. The compressor 14 compresses the low-pressure refrigerant into a high-pressure and high-temperature gaseous refrigerant. The condenser 15 liquefies the high-pressure refrigerant and sends it to the expansion valve 16 to reduce its pressure to form a low-pressure and low-temperature liquid refrigerant. The evaporator 17 performs heat exchange between the low-pressure and low-temperature liquid refrigerant and water to reduce the temperature of the cooled water to below zero. Preferably, one end of the temperature sensor 3 connected to the cooling assembly is respectively installed at the inlet and outlet of the evaporator 17 to measure the water temperature before and after cooling to ensure that the set values ​​of the initial water temperature and the cooling water temperature meet the test requirements. The other end of the temperature sensor 3 is electrically connected to the electronic control panel 4.

[0064] In this embodiment, the electronic control panel 4 is used to turn on the heating component, the cooling component and the wiper 24, control and monitor the set values ​​of the temperature in the heating component and the cooling component and the set value of the humidity of the erosion wet sand 21 in the erosion simulation environment box 2;

[0065] Reference Figure 2 , Figure 5 The environmental simulation box 2 is provided with erosion wet sand 21, stainless steel short column 23 and wiper 24. The erosion wet sand 21 refers to wet sand containing erosion solution, which is used to simulate the erosion environment of the Gobi Desert. The type and concentration of the erosion solution are determined according to the results of the on-site environmental survey. In this embodiment, the erosion solution is a sulfate solution, and its SO42- The concentration is 25000 mg / L, the humidity of the sand is controlled at 60%, the thickness is 200 mm, and a humidity sensor 26 is buried in the eroded wet sand 21; the concrete specimen 22 is inserted on the stainless steel short column 23 in the environmental simulation box 2, and the concrete specimen 22 and the eroded wet sand 21 are at the same horizontal line. The concrete specimen 22 is prepared according to the construction mix ratio of the actual environment of the Gobi Desert. After 28 days of standard curing, it is placed in the eroded wet sand 21 for erosion test. The water-cement ratio (0.35, 0.39 and 0.43) is adjusted according to the construction mix ratio and strength requirements. According to the most dense stacking principle and The sand ratio (36%, 39% and 42%) is adjusted according to the slump requirement, and the amount of air-entraining agent (1‰, 2‰ and 3‰) is adjusted according to the air content requirement. In this embodiment, the size of the concrete specimen 22 is a cube of 100mm×100mm×100mm, and its mix ratio is shown in Table 1. After the concrete specimen 22 is formed, it is placed in a standard curing room with a temperature of 20±2°C and a humidity of 90±5% for curing for 28 days, and then placed on a stainless steel short column 23 to avoid direct contact with the copper water pipe 18. The stainless steel short column 23 and the concrete specimen 22 are both buried in the erosion wet sand 21 for corrosion test.

[0066] Table 1 Concrete mix ratio (kg / m 3 )

[0067]

[0068] Glass observation windows 25 are arranged on all sides of the environmental simulation box 2. The glass observation windows 25 are double-layer hollow settings and are used to observe the humidity of the eroded wet sand 21 and the erosion of the concrete specimen 22. Epoxy resin sealant is evenly coated on all sides to ensure that the temperature and humidity in the environmental simulation box 2 are not affected by the external environment; the wiper 24 is connected to the top of the inner side of the environmental simulation box 2 to scrape off the water mist generated on the glass observation window 25 due to high temperature, low temperature, dry-wet cycle and freeze-thaw cycle during the erosion simulation experiment.

[0069] like Figure 2 , Figure 6As shown, the DIC image acquisition system includes an image acquisition box 5 and a collector component, the collector component includes a camera, an electric slide 53, an electric slide controller 54 and a data transmission line 55, the electric slide 53 is installed on the inner top wall of the image acquisition box 5, the electric slide controller 54 is installed on the outside of the image acquisition box 5, the camera is movably connected to the electric slide 53 through a slider, the data transmission line 55 includes two parts, one end of the data transmission line 55 of one part is connected to the electric slide controller 54, and the CCD industrial camera 50 on the electric slide 53 is controlled to move accurately to a specified position according to a control signal sent by the image data analysis and calculation system 6, and the other end is connected to a computer; one end of the data transmission line 55 of the other part is connected to the CCD industrial camera 50, and the other end is connected to the computer, and the image data taken by the CCD industrial camera 50 is sent to the data analysis and calculation system 6, so as to provide data support for the next step of image analysis and calculation of the volume stability of the concrete specimen 22.

[0070] The camera includes a CCD industrial camera 50, an industrial lens 51 and a polarized illumination light source 52. The CCD industrial camera 50 is mounted on a slider 56 and movably connected to an electric slide rail 53, and is used to take pictures of the concrete specimen 22 during the erosion process, and observe and analyze the influence of temperature and humidity changes on the volume stability of the concrete. The CCD industrial camera 50 should have high resolution, high frame rate, high sensitivity and high dynamic range, and should also have a fast shutter speed. The CCD industrial camera 50 has a connection method with a computer or other device, and is compatible with existing image processing tools. In this embodiment, the model of the CCD industrial camera 50 is Basler ace acA2440-75um, with a resolution of 2448x2048 pixels, a frame rate of 30fps, a dynamic range of 70dB, and is compatible with C-mount lenses, which can meet the needs of industrial lenses 51 with different focal lengths and apertures. The CCD industrial camera 50 is equipped with a GigE interface to ensure high bandwidth and stable data transmission, and is compatible with LabVIEW, MATLAB and Open CV and other existing image processing software and analysis tools are compatible, which facilitates the processing and analysis of image data; the industrial lens 51 is connected to the bottom of the CCD industrial camera 50, and the model of the industrial lens 51 is Computar M2514-MP2 supports high-resolution imaging and low distortion characteristics, with 16mm focal length, F / 1.4 aperture and 25mm focal length, F / 1.8 aperture, respectively. It can provide high-quality images of the concrete specimen 22 during the erosion process under different shooting distances and lighting conditions, and adapt to the needs of different DIC detection technologies; the polarized illumination light source 52 is connected to the CCD industrial camera 50. The polarized illumination light source 52 determines the light source type, polarizer type, polarization direction and light source intensity based on the requirements of illumination uniformity, light source life, light source parameter adjustability and color temperature. The polarized illumination light source 52 consists of two independent and positionally adjustable sub-light sources, which are respectively placed on both sides of the CCD industrial camera 50. The polarizer uses a circular polarizer made of glass. The light source and the front polarizer of the camera are both set to right-handed circular polarization, which can maintain the polarization state in a more complex optical path, and a polarizer is installed for use in conjunction to eliminate the reflection points that appear during the camera imaging process under complex environments and improve the image quality; the initial light intensity is 2000lx, and is adjusted according to the reflection of the concrete specimen 22.

[0071] Furthermore, the electric slide rail 53 is made of stainless steel and is placed on the upper inner side of the image acquisition box 5, and is used to install and move lighting equipment such as the CCD industrial camera 50, the industrial lens 51, the polarized lighting source 52, and the data transmission line 55; preferably, the lighting equipment and the data transmission line 55 are connected to the CCD industrial camera 50 and then connected to the electric slide rail 53, and the electric slide rail controller 54 is embedded in the electric slide rail 53. The electric slide rail controller 54 is used to control the movement of the electric slide rail 53 on the track, thereby realizing the automatic detection of the concrete specimen 22 during the entire erosion test process.

[0072] The data transmission line 55 includes a USB data transmission line, an RS-485 data line, an HDMI data line and a Camera Link data line; preferably, the USB data transmission line type is 3.0, the RS-485 data line is used to control devices such as cameras, light sources and slide rails to ensure synchronous operation and high-precision data acquisition, the HDMI data line type is 2.0, supporting 4K resolution and higher transmission rates, and the Camera Link data line type is Full Configuration, which is used to connect the CCD industrial camera 50 and the computer host 61 to achieve high-speed image data transmission.

[0073] like Figure 2 As shown, the image data analysis and calculation system 6 includes hardware and image processing software integrated on the hardware, wherein: the hardware includes a trigger collector 60 and a computer, the trigger collector 60 is electrically connected to the computer via a data line, and is used to transmit the image data collected by the camera to the computer;

[0074] The trigger collector 60 includes an input interface, a trigger signal processing unit, a control logic unit, a time management unit, an output interface, a multi-channel control unit and a power supply unit; preferably, the input interface is used to receive the trigger signal of an external sensor, the number of input channels is four, and the input signal type is a digital signal; the trigger signal processing unit is used to remove noise and interference in the input signal, and the gain value is "2x"; the control logic unit sends the processed trigger signal to the output interface, level triggering, and "AND" operation; the time management unit is set to a variable delay with an accuracy of 1μs, which is used to manage the time parameters of the trigger signal; the output interface transmits the processed trigger signal to the CCD industrial camera 50, and the number of output channels is two; the multi-channel control unit is an independent channel, which is used to realize the synchronous triggering of multiple CCD industrial cameras 50, and the power supply unit is a 24V DC power supply, which provides a stable power supply for each component of the trigger collector 60.

[0075] The computer includes a computer host 61 and computer accessories 62 that are compatible with it. The computer host 61 processor is selected from Intel Core i7 or i9 series, the memory is 64GB, the image processor is selected from NVIDIA GeForce RTX 40 series, a 1TB solid-state drive is selected as the main storage, a 2TB mechanical hard drive is used for large data storage, the operating system is selected from Windows 11, and the computer accessories 62 include a monitor, keyboard and mouse. The monitor size is 27 inches, supports Adobe RGB color gamut, and has a resolution of 4k (3840×2160), which can accurately restore image colors and facilitate image analysis and processing. The keyboard and mouse parameters can be configured in the conventional way.

[0076] The image processing software includes an image data preprocessing module, an image data analysis module and an image data storage and management module, which are respectively used for preprocessing, analyzing and storing and managing the image data received by the computer; among them, the image data preprocessing module uses the U-Net neural network for image denoising, correction and enhancement, the image data analysis module uses the Mask R-CNN convolutional neural network for image segmentation and feature extraction, and the image data storage and management module uses the MySQL database management system for storage, management and backup of image data.

[0077] Embodiment 2:

[0078] like Figure 2 As shown, the test device for the volume stability of concrete in the Gobi Desert erosion environment based on the DIC technology in the first embodiment is used to perform a Gobi Desert erosion environment simulation experiment with high temperature, low temperature, dry-wet cycle and freeze-thaw cycle coupling on the concrete specimen 22, so as to obtain the volume stability of the concrete. The specific test method includes the following steps:

[0079] Step 1: Establishment of indoor Gobi Desert erosion simulation environment:

[0080] Take Nukus in Uzbekistan as an example. The region has cold winters, continuous rain and snow, hot summers, dry and rainless weather, and hot days and cool nights. This is a typical Gobi Desert environment. Figure 3 As shown, this embodiment investigates in detail the temperature and weather changes in the region from 10 am to 3 pm in 2022, and calculates that the erosion time of the annual average high temperature (≥35°C) and the annual average low temperature (≤-20°C) in the region are 22.5d and 0.75d respectively, and the average temperature of the coldest month in the region is basically -3°C to -10°C;

[0081] When the lowest surface temperature is ≤-3℃ and the highest surface temperature is >0℃, the concrete is subjected to one freeze-thaw action. According to the temperature change in the area, the average annual freeze-thaw cycle in the area is about 51 days, so the dry-wet cycle in one year is about 290.75 days. Simulating the actual environment for 5 years as an erosion cycle, the high-temperature erosion time is 255 days, the low-temperature erosion time is 3.75 days, the dry-wet cycle is about 1453.75 days, and the freeze-thaw cycle is about 112.5 days. The erosion solution type is Na2SO4 solution, of which SO4 2- The concentration is 9.22%;

[0082] Establish an indoor simulation process of the Gobi Desert erosion environment, and set the duration of different erosion stages. The high temperature erosion stage lasts for 28 days, the low temperature erosion stage lasts for 1 day, the dry-wet cycle erosion stage lasts for 2 days, and the freeze-thaw cycle erosion stage lasts for 43 days.

[0083] The equipment control box 1 in the indoor simulation of the erosion environment is used to control the temperature and humidity of the erosion environment. The environmental simulation box 2 is used to place the erosion wet sand 21 and the concrete specimen 22. The equipment control box 1 and the environmental simulation box 2 together constitute a erosion environment simulation system.

[0084] Step 2: Preparation and pretreatment of concrete specimens:

[0085] According to the mix ratio of the actual construction site in the Gobi Desert, a concrete specimen 22 was prepared. After the mixture was stirred, it was poured into a 100mm×100mm×100mm cubic mold, placed on a vibration table for vibration shaping, and removed from the mold after curing for 1 day. It was then placed in a standard curing room with a temperature of 20±2°C and a humidity of 90±5% for curing for 28 days. The upper surface of the concrete specimen 22 was cleaned with a hard brush and clean water, placed in a natural environment to dry for 24 hours, and then polished with 120-mesh quartz sandpaper for smoothness and then subjected to speckle spraying.

[0086] During the speckle spraying, first keep the spray gun 30 cm away from the surface of the concrete specimen 22, randomly spray a layer of matte white primer and then spray the matte black paint, and use multi-angle spraying to avoid fixed-angle spraying; form a high-contrast, evenly distributed speckle pattern on the upper surface of the concrete specimen 22, and ensure that the coverage of the speckle pattern is between 60% and 80%, and tightly adhere to the concrete specimen 22. After the speckle spraying is completed, dry for 2 hours.

[0087] The prepared concrete specimen 22 is placed in the eroded wet sand 21 , and the exposed upper surface of the concrete specimen 22 is used as the acquisition surface for subsequent DIC image acquisition. The eroded wet sand 21 and the concrete specimen 22 are both located in the environmental simulation box 2 .

[0088] Step 3: Test device installation:

[0089] The water supply component, heating component and cooling component in the equipment control box 1, the erosion wet sand 21, the concrete specimen 22 and the wiper 24 in the environmental simulation box 2, and the electric slide rail 53, the camera and the data transmission line 55 in the image acquisition box 5 are arranged in sequence;

[0090] Then, the image data analysis and calculation system 6 is connected to the DIC image acquisition system;

[0091] Install the equipment control box 1, the environment simulation box 2, the image acquisition box 5, and the image data analysis and calculation system 6 in sequence;

[0092] First, place the water tank 10, the heating component and the cooling component at the bottom of the equipment control box 1, the water tank 11 is installed on the right side of the equipment control box 1, and the heating component and the cooling component are installed on both sides of the heat insulation baffle 19 in the equipment control box 1;

[0093] Subsequently, one end of the copper water pipe 18 is placed in the water tank 11, and returns to the water tank 11 after passing through the heating component / cooling component, the centrifugal water pump 12 and the eroded wet sand 21, thus forming a circulation loop;

[0094] Then, one end of the temperature sensor 3 is respectively placed at the inlet and outlet of the heating rod 13 and the inlet and outlet of the evaporator 17, and the other end of the temperature sensor 3 is electrically connected to the electronic control panel 4. The concrete specimen 22 is placed on the raised platform in the environmental simulation box 2 to ensure that the concrete specimen 22 remains stable during the image acquisition process. The eroded wet sand 21 is laid on the bottom of the environmental simulation box 2, and its thickness is higher than the copper water pipe 18 and is flush with the upper surface of the concrete specimen 22; one end of the humidity sensor 26 is buried in the eroded wet sand 21, and the other end is electrically connected to the electronic control panel 4; the wiper 24 is installed on the inner side of the top of the environmental simulation box 2; the electronic control panel 4 is installed on the outer side of the front facade of the equipment control box 1 to control the erosion environment simulation system, and its circuit passes through the inner side of the equipment control box 1 and is connected to the power cord 7 and the power socket 8 at the rear;

[0095] The interface of the electronic control panel 4 includes an equipment control area, an erosion environment temperature and humidity control area, and an ancillary facility control area; the equipment control area includes the "start" and "stop" buttons of the centrifugal water pump 11, and the corresponding buttons are pressed at the beginning and end of each erosion stage, the operation of the heating component and the cooling component and their respective "start" and "stop" buttons; the erosion environment temperature and humidity control area includes a temperature and humidity detection area and temperature "increase" and "decrease" buttons; the ancillary facility control area includes a wiper 24 frequency knob, which is provided with three gears of "low speed", "medium speed" and "fast speed";

[0096] During the high temperature erosion stage, click the "Start" button of the heating component, and set the heating time according to the high temperature erosion duration and temperature in step 1, click the "Increase" button to increase the temperature to 45°C, and click the "Stop" button after the specified time to stop heating;

[0097] During the low-temperature erosion stage, click the "Start" button of the cooling component, set the cooling time according to the duration and temperature of the low-temperature erosion stage in step 1, click the "Lower" button to lower the temperature to -35°C, and click the "Stop" button after the specified time to stop cooling;

[0098] During the dry-wet cycle erosion stage, click the "on" button of the heating system to raise the temperature of the environmental simulation box 2 to 60°C and maintain it for 6 hours, then stop heating, cool it naturally for 2 hours, and then add Na2SO4 erosion solution to soak the wet sand for 16 hours;

[0099] During the freeze-thaw cycle erosion stage, a rapid freeze-thaw cycle is performed every 6 hours. The heating component and the cooling component need to be turned on alternately to ensure that the temperature of the environmental simulation box 2 is not higher than 10°C and not lower than -20°C. Click the "Stop" button after the cycle ends;

[0100] For the installation of the image acquisition box 5, firstly, the electric slide rail 53 is welded to the inner side of the top of the image acquisition box 5, and one end of the electric slide rail controller 54 is connected to the slider 56, and the other end is connected to the computer host 61, so as to control the movement of the slider 56 on the electric slide rail 53;

[0101] After assembling the CCD industrial camera 50, the industrial lens 51 and the polarized illumination light source 52, they are connected to the slider 56, and the angle of the CCD industrial camera 50 is adjusted to align it with the observation area of ​​the concrete specimen 22;

[0102] Finally, one end of the data transmission line 55 is connected to the CCD industrial camera 50, and the other end is connected to the interface of the computer host 61 for transmitting the collected image data. The computer host 61 is used to control the moving direction of the CCD industrial camera 50, the shooting direction of the industrial lens 51 and the brightness of the polarized illumination light source 52 respectively;

[0103] For the installation of the image data analysis and calculation system 6, first, the computer host 61, computer display, keyboard and mouse, computer accessories 62 and other hardware devices are installed in sequence; then, the software system, CCD industrial camera 50 and trigger collector 60, MATLAB data analysis software and Open CV image processing library are installed; finally, the camera parameters and electric slide rail 53 are configured, and the CCD industrial camera 50 is calibrated before installation to ensure its measurement accuracy;

[0104] The specific calibration method for the CCD industrial camera 50 is as follows:

[0105] (1) Fix the CCD industrial camera 50 on the same equipment as the test process to ensure that the CCD industrial camera 50 does not move during the calibration process, and adjust the focal length of the CCD industrial camera 50 so that the calibration points on the calibration plate can be clearly observed;

[0106] (2) Select a 12×9 chessboard calibration plate, on which the calibration points should be evenly distributed and have high contrast;

[0107] (3) Take at least 10 images of the calibration plate from different angles and positions to ensure that the calibration points of the calibration plate are clearly visible in each image;

[0108] (4) Use the automatic extraction function in calibration software such as Open CV to identify the calibration points in the image, calculate the distortion parameters of the captured image, and eliminate the distortion using the following formula;

[0109] x revised =x(1+m1r 2 +m2r 4 +m3r 6 )+[2μ1xy+μ2(r 2 +2x 2 )]

[0110] y revised =y(1+m1r 2 +m2r 4 +m3r 6 )+[μ1(r 2 +2y 2 )+2μ2xy]

[0111] Where: (x, y) is the corrected pixel coordinate; (x revised ,y revised ) is the corrected pixel coordinate; r is the distance from the point to the pixel center, r 2 =x 2 +y 2 ; m1, m2 and m3 represent radial distortion parameters respectively; μ1 and μ2 are tangential distortion parameters;

[0112] When the calculated reprojection error ω is less than 0.1, it means that the calibration of the CCD industrial camera 50 and the debugging of the DIC system are completed, and the reprojection error ω can be calculated by the following formula;

[0113]

[0114] Where: N is the total number of calibration points in the calibration image;

[0115] Furthermore, considering the detection of the long-term volume stability of the concrete specimen 22 during the erosion process, the actual ambient light will experience a change from night to day, resulting in a significant change in the grayscale of the image of the concrete specimen 22 received by the CCD industrial camera 50, which reduces the measurement accuracy and stability of DIC. In this embodiment, the average grayscale is used to characterize the change in light intensity. The larger the value, the higher the contrast of the image, which is more conducive to the CCD industrial camera 50 to perform accurate search. The average grayscale suitable for the erosion process is determined by the following formula:

[0116]

[0117] Where: W and H are the width and height of the image respectively; is pixel x ij The modulus of the grayscale gradient; f x (x ij ) and f y (x ij ) are pixel points x ij First order grayscale derivatives in the x and y directions.

[0118] Step 4: Image data acquisition of concrete specimens:

[0119] Turn on the computer host 61, and start the relevant image acquisition and analysis software, initialize the CCD industrial camera 50, the industrial lens 51, the electric slide 53 and the electric slide controller 54, preheat the CCD industrial camera 50 for 1.5-2 hours, reduce the lens distortion caused by the self-heating of the CCD industrial camera 50, and ensure the normal operation of the equipment during the measurement process; set the moving path and moving speed of the electric slide 53 to ensure the stability of the CCD industrial camera 50 during the acquisition process;

[0120] Start the erosion environment simulation system and the image acquisition program, and the CCD industrial camera 50 starts to take images of the upper surface of the concrete specimen 22, with a sampling frequency of one image every 5 minutes. The sampling time is determined according to the erosion test scheme described in step 1, and 500 images are extracted at equal time intervals of 5 minutes for analysis;

[0121] After the surface image of a concrete specimen 22 is captured, the electric slide rail 53 moves along a preset path to sequentially capture the upper surface images of the remaining concrete specimens 22 in the environmental simulation box 2; the image acquisition process is detected in real time in the image acquisition box 5, and the image data is checked to ensure that no data is lost or damaged; the acquired image data is stored in the computer host 61, and the data file is named according to the specimen number and the acquisition time, and the data is backed up regularly;

[0122] Preferably, the following least square distance normalization (ZNCCD) is used as the judgment criterion for image feature matching, which is used to quantitatively evaluate the similarity of the shooting area of ​​the concrete specimen 22 before and after deformation. The value range of ZNCCD is [-1, 1]. The closer the value is to 1, the better the image correlation is.

[0123]

[0124] Where: u, v are the integer pixel displacements of the center point of the reference sub-region in the x and y directions respectively; M is the half width of the image sub-region, and the sub-region size is (2M+1)×(2M+1); f(x i ,y j ) and g(x' i , y' j ) are the grayscale values ​​of each pixel in the reference sub-area and the target sub-area respectively; f m With g m are the average grayscale values ​​of each pixel in the reference sub-area and the target sub-area respectively; x' i With y' j is the coordinate of any point in the deformed subset;

[0125] Since the concrete specimen 22 not only includes its own rigid body displacement during the erosion process, but also includes shrinkage deformation caused by temperature and humidity, etc., a first-order shape function is required to reflect the changes in the subset shape. The expression of the first-order shape function is as follows:

[0126] x i '=x0+u+Δu+u x Δx i +u y Δy j

[0127] y' j =y0+v+Δv+v x Δx i +v y Δy j

[0128] Where: x0 and y0 are the coordinates of the origin; Δu and Δv are the displacements of the center point at the sub-pixel level; u x 、u y 、v x With v y are the first-order gradients of u and v in the x and y directions respectively; Δx i with Δy j It means (x i ,y j ) is the coordinate difference between (x0, y0) and (x0, y0) in the x and y directions.

[0129] Step 5: Analyze the volume stability of concrete specimens:

[0130] The collected surface image is processed and corrected by using image processing software, and then the visual image of the concrete specimen 22 is output and exported as an image data file, and the volume stability of the concrete specimen 22 is calculated through the image data file.

[0131] The image data preprocessing module and image data analysis module of the image processing software are used to perform preprocessing work such as denoising and enhancement on the collected images, and geometric correction is performed on them; the DIC software is used to output visualization images such as the displacement field of the concrete specimen 22, and the color mapping and display settings are adjusted to obtain clearer results; according to the displacement components of the concrete specimen 22 in the x and y directions, the finite difference method is used to approximate the displacement gradients in the corresponding directions to obtain the strain components ε of the concrete specimen 22 in the x and y directions xx , ε yy and ε xy / ε yx ; Export the displacement field and strain field as an image file or a data file, calculate the average volume strain of the concrete specimen 22 as the volume change rate, and evaluate the average strain ε of the concrete specimen 22 by analyzing the volume change rate and strain distribution average and the maximum strain ε max Isovolumetric stability index.

[0132] In this embodiment, step 2 and step 3 can refer to Figure 4 , Figure 5 Understand the structure marked in the figure. Steps 4 and 5 can refer to Figure 6 , Figure 7 Understand the structure and system building process marked in.

[0133] The above shows and describes the basic principles, main features and beneficial effects of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A test device for the volume stability of concrete in Gobi Desert erosion environment based on DIC technology, characterized in that: include: An erosion environment simulation system, in which a concrete specimen (22) is placed to simulate the erosion effect of the complex environment of the Gobi Desert on the concrete specimen (22); A DIC image acquisition system connected to the erosion environment simulation system and used to obtain image data of a concrete specimen (22) under a erosion environment simulation test; An image data analysis and calculation system (6) is connected to the DIC image acquisition system and is used to receive image data transmitted by the DIC image acquisition system and calculate the volume stability of the concrete specimen (22) at different erosion stages based on the image data.

2. A testing device for the volume stability of concrete in a Gobi Desert erosion environment based on DIC technology according to claim 1, characterized in that: The erosion environment simulation system comprises an equipment control box (1), an anti-corrosion partition (20) and an environment simulation box (2) which are arranged in order from bottom to top, wherein: The equipment control box (1) is used to control the simulated temperature and humidity in the environmental simulation box (2); An anti-corrosion partition (20) is provided between the environmental simulation box (2) and the equipment control box (1); The environmental simulation box (2) is used to carry out a Gobi desert erosion environmental simulation test on a concrete test piece (22) placed therein.

3. A testing device for the volume stability of concrete in Gobi Desert erosion environment based on DIC technology according to claim 2, characterized in that: An electronic control panel (4) is arranged outside the equipment control box (1), and a water supply component, a heating component and a cooling component connected to the electronic control panel (4) are arranged inside the equipment control box. The water supply component comprises a water tank (11) and a copper water pipe (18). The water tank (11) is installed at the upper right of the equipment control box (1). The copper water pipe (18) is inserted into the water tank (11) in an inverted U shape. The upper end of the copper water pipe (18) extends into the environmental simulation box (2). The heating component and the cooling component are respectively connected to the copper water pipe (18). Temperature sensors (3) are arranged on the heating component and the cooling component, and the temperature sensor (3) is electrically connected to the electronic control panel (4). The operation of the water supply component, the heating component, the cooling component and the temperature sensor (3) is adjusted and controlled by the electronic control panel (4).

4. A testing device for the volume stability of concrete in a Gobi Desert erosion environment based on DIC technology according to claim 3, characterized in that: An environmental simulation box (2) is provided with corrosive wet sand (21) and a wiper (24); a concrete specimen (22) is located in the environmental simulation box (2) and inserted into the corrosive wet sand (21); the wiper (24) is connected to the top of the environmental simulation box (2); a humidity sensor (26) is buried in the corrosive wet sand (21); and the humidity sensor (26) is electrically connected to an electronic control panel (4).

5. A testing device for the volume stability of concrete in a Gobi Desert erosion environment based on DIC technology according to claim 4, characterized in that: The DIC image acquisition system comprises an image acquisition box (5) and an acquisition device component, wherein the acquisition device component comprises: An electric slide rail (53) mounted on the inner top wall of the image acquisition box (5); An electric slide rail controller (54) is embedded in the electric slide rail (53); A camera is movably connected to the electric slide rail (53) via a slider (56); The data transmission line (55) comprises two parts, wherein two ends of one part of the data transmission line (55) are respectively connected to the electric slide rail controller (54) and the image data analysis and calculation system (6), and two ends of the other part of the data transmission line (55) are respectively connected to the camera and the image data analysis and calculation system (6).

6. A device for testing the volume stability of concrete in a Gobi Desert erosion environment based on DIC technology according to claim 5, characterized in that: The camera comprises a CCD industrial camera (50), an industrial lens (51) and a polarized illumination light source (52); the CCD industrial camera (50) is mounted on an electric slide rail (53); the industrial lens (51) is arranged at the bottom of the CCD industrial camera (50); and the polarized illumination light source (52) is connected to the CCD industrial camera (50).

7. A testing device for the volume stability of concrete in a Gobi Desert erosion environment based on DIC technology according to claim 6, characterized in that: The image data analysis and calculation system (6) comprises hardware and image processing software integrated on the hardware, wherein: The hardware includes a trigger collector (60) and a computer. The trigger collector (60) is connected to the computer via a data line and is used to transmit the image data collected by the camera to the computer. The image processing software includes an image data preprocessing module, an image data analysis module and an image data storage and management module, which are respectively used to preprocess, analyze and store the image data received by the computer.

8. A method for testing the volume stability of concrete in a Gobi Desert erosion environment based on DIC technology, the method testing the volume stability of concrete based on the testing device of any one of claims 1 to 7, characterized in that: The following steps are involved: S1 Establishment of indoor Gobi Desert erosion simulation environment: Use the equipment control box (1) to adjust the erosion environment temperature and humidity and set the time of different erosion stages; Preparation and pretreatment of S2 specimens: concrete specimens (22) were prepared according to the simulated actual environment of the Gobi Desert, and speckle spraying was performed after standard curing; S3 Equipment installation: Arrange the water supply component, heating component and cooling component in the equipment control box (1), the eroded wet sand (21), concrete specimen (22) and wiper (24) in the environmental simulation box (2), and the electric slide rail (53), camera and data transmission line (55) in the image acquisition box (5) in sequence, and then connect the image data analysis and calculation system (6) with the DIC image acquisition system; S4: collecting image data of the specimens: photographing a surface image of a concrete specimen (22), and then photographing surface images of the remaining concrete specimens (22) when the electric slide rail (53) moves, and transmitting and storing the collected surface images in real time to a computer; S5 analyzes the volume stability of the specimen: uses image processing software to process and correct the collected surface image, then outputs a visual image of the concrete specimen (22) and exports it as an image data file, and calculates the volume stability of the concrete specimen (22) through the image data file.

9. A testing method for a testing device for testing volume stability of concrete in Gobi Desert erosion environment based on DIC technology according to claim 8, characterized in that: In step S3, the steps of installing the water supply component, the heating component and the cooling component in the equipment control box (1) include: Place one end of a copper water pipe (18) in a water tank (11); The heating component and the cooling component are respectively arranged on two sides of the middle of the equipment control box (1); After the installation is completed, the copper water pipe (18) passes through the heating component and the cooling component and corrodes the wet sand and then returns to the water tank (11), forming a circulation loop.

10. A testing method for a testing device for the volume stability of concrete in a Gobi Desert erosion environment based on DIC technology according to claim 8, characterized in that: In step S3, the steps of installing the corrosive wet sand (21), the concrete test piece (22) and the wiper (32) in the environmental simulation box (2) include: The concrete specimen (22) is placed on a stainless steel short column (23) in an environmental simulation box (2); Laying corroded wet sand (21) in the environmental simulation box (2), wherein the thickness of the corroded wet sand (21) is higher than the copper water pipe (18), and the corroded wet sand (21) is kept flush with the surface of the concrete specimen (22); A humidity sensor (26) is buried in the eroded wet sand (21), and the humidity sensor (26) is connected to the electronic control panel (4); The wiper (24) is mounted on the inner top wall of the environmental simulation box (2).

Images