Test Device and Method for Anti-Ion Erosion Performance of Cracked Concrete

Abstract

The present application discloses a test device and method for the anti-ion erosion performance of cracked concrete, which relates to the field of concrete durability performance testing. The problem that the crack width is not easy to control is solved, and the experimental research under the coupling action of load and erosion solution is realized. The test device includes upper and lower support assemblies and two loading plates; the two loading plates are arranged in parallel, and are provided with a first through hole and a plurality of second through holes thereon; the first through hole is located at the center of the loading plate, and the plurality of second through holes are all located on the outer periphery of the first through hole; both ends of the upper support assembly and the lower support assembly are erected at the second through holes; a salt solution tank is arranged between the upper support assembly and the lower support assembly; the middle part of the reinforced concrete specimen is located in the salt solution tank, the steel bar at the first end extends out of one of the first through holes and is fastened to the holding nut, and the steel bar at the second end extends out of the other first through hole and is connected to the loading nut. The present application also discloses a test method based on the above test device.

Description

Technical Field

[0001] This application relates to the field of concrete durability performance testing, and particularly to an experimental device and method for the anti-ion erosion performance of cracked concrete. Background Art

[0002] Erosive ions (such as Cl - , SO4 2- etc.) in marine environments or saline soil environments are the main causes of steel bar corrosion and concrete deterioration. Due to the very low tensile strength of concrete, a very small tensile strain (about 100×10 -6 ) may cause cracks in it, and the interconnection of cracks will form a large number of mass transfer channels, increasing the transmission speed of moisture, oxygen, and soluble harmful media, and thus easily leading to a significant shortening of the service life of concrete structures. In summary, it is necessary to study the influence of cracks on the durability performance of concrete structures.

[0003] Currently, scholars at home and abroad have carried out extensive research on the anti-ion erosion performance of cracked concrete and designed different production methods for cracked concrete specimens, mainly including the splitting method, the flexural loading method, the precast crack method, the expansion core method, etc. However, these test methods also have some deficiencies. For example, multiple cracks often appear simultaneously when using the splitting method, making it difficult to accurately and quantitatively describe the width of a single crack; the cross-sectional shape of the crack obtained by the flexural loading method is wedge-shaped. At this time, the crack depth and width jointly affect the diffusion effect of erosive substances, and the obtained test results cannot be considered to be only affected by the crack width; the crack width obtained by the precast crack method is usually large, and the roughness and tortuosity of the cracking surface are quite different from those of actual engineering cracks; it is difficult to control the development of the crack width and tortuosity generated by the expansion core method, and it is difficult to quantitatively describe the degree of internal damage. At the same time, since the vast majority of concrete structures are in service under load, ignoring the external load effect and only considering the research on damaged cracked concrete without load will have a large difference from the actual engineering situation.

[0004] Therefore, it is necessary to provide a loading device and test method for the long-term durability performance research of cracked concrete under the action of load and solution environment, so as to facilitate the study of the influence of cracks on steel bar corrosion and concrete deterioration, etc. under the coupling action of erosive ions and load in durability tests. Summary of the Invention

[0005] Embodiments of the present application provide a test device and method for the anti-ion erosion performance of cracked concrete. By performing two-point three-point bending loading and one longitudinal tensile loading on the steel bars in the specimen, single crack prefabrication is achieved, solving the problem in the prior art that the crack width cannot be effectively controlled. At the same time, a holding device is used to continuously axially pull the steel bars, realizing the holding work on the reinforced concrete specimen with a single crack. A supporting salt solution tank is used to realize the experimental research under the coupling action of load and erosion solution, ensuring that the holding device is not corroded during long-term durability tests, saving the solution and facilitating solution replacement.

[0006] To achieve the above object, on the one hand, embodiments of the present application provide a test device for the anti-ion erosion performance of cracked concrete, including an upper support assembly, a lower support assembly, and two loading plates; the two loading plates are arranged in parallel, and a first through hole and a plurality of second through holes are provided on the loading plates; the first through hole is located at the center of the loading plate, and the plurality of second through holes are all located on the outer periphery of the first through hole; both ends of the upper support assembly and the lower support assembly are mounted at the second through holes; the upper support assembly and the lower support assembly can prevent the two loading plates from approaching each other; a salt solution tank for accommodating salt solution is provided between the upper support assembly and the lower support assembly; the middle part of the reinforced concrete specimen is located in the salt solution tank, the steel bar at the first end of the reinforced concrete specimen extends out of one of the first through holes and is fastened to a holding nut, and the steel bar at the second end extends out of the other first through hole and is fastened to a loading nut.

[0007] Further, the loading plate is a square plate, and both the upper support assembly and the lower support assembly are two, and the two upper support assemblies and the two lower support assemblies are respectively arranged near the corresponding vertices of the loading plate.

[0008] Further, the upper support assembly includes a lead screw and fixed nuts connected to both ends of the lead screw, and the fixed nuts are located inside the corresponding loading plates; the lower support assembly has the same structure as the upper support assembly.

[0009] Further, an installation plate is provided on the lower support assembly, and the salt solution tank is arranged on the installation plate.

[0010] Further, the salt solution tank is a rectangular shell with an upward opening, and notches are provided on the two side walls in the length direction of the rectangular shell. The steel bars at both ends of the reinforced concrete specimen sequentially extend out of the corresponding notches and second through holes and are respectively fastened to the holding nut and the loading nut, and the steel bars at both ends of the reinforced concrete specimen are sealed with the side walls of the salt solution tank through sealant.

[0011] On the other hand, an embodiment of the present application further provides a test method based on the above test device for the anti-ion erosion performance of cracked concrete, including the following steps: S1. Prepare a reinforced concrete specimen; S2. Prefabricate a target uniform crack, where the target uniform crack is a single crack with a uniform width; S3. Continuously apply an axial tensile load to the reinforced concrete specimen through the test device for the anti-ion erosion performance of cracked concrete until a target qualified crack is obtained; S4. Conduct an anti-ion erosion performance test on the reinforced concrete specimen through the test device for the anti-ion erosion performance of cracked concrete; S5. After the anti-ion erosion performance test is completed, unload the reinforced concrete specimen and detect the damage condition of the concrete and the corrosion condition of the steel bars.

[0012] Further, the reinforced concrete specimen is a quadrangular prism reinforced concrete specimen, and external thread segments are processed on the steel bars at both ends thereof; S2 includes the following steps: S21. Perform two-point three-point bending loading on the reinforced concrete specimen to obtain a preliminary load crack; S22. Apply an axial tensile load to the reinforced concrete specimen to obtain a target uniform crack.

[0013] Further, S21 includes the following steps: S211. Define the four formed surfaces of the reinforced concrete specimen: Define the formed surface as the bottom surface, the opposite surface as the front surface, and the rest as the A side surface and the B side surface; S212. Perform the first three-point bending loading with the B side surface of the specimen as the tension surface. When the crack on the front surface or the bottom surface extends to a preset depth, stop loading and record the bending moment value at this time; S213. Perform the second three-point bending loading with the A side surface of the specimen as the tension surface. Stop loading when the bending moment reaches the bending moment value in S212 to obtain a preliminary load crack.

[0014] Further, S3 includes the following steps: S31. Assemble the upper support assembly, the lower support assembly, the reinforced concrete specimen, two loading plates and the tensioning device to form a tensioning assembly; S32. Operate the tensioning device to perform stable loading on the reinforced concrete specimen until the target qualified crack width is reached and then stop loading; S33. Fasten the holding nut at the front end of the tensioning device to the steel bar at the end of the reinforced concrete specimen and unload the tensioning device.

[0015] Further, S4 includes the following steps: S41. Horizontally place the tensioning assembly in step S33; S42. Use a crack width measuring instrument to measure the width of the target qualified cracks, take the crack width distribution measured this time as the final test crack width level, and record the maximum crack width at each measuring point and the average crack width of each target erosion surface; S43. Install a salt solution tank to ensure that the middle part of the reinforced concrete specimen is located inside the salt solution tank, and the steel bars at both ends of the reinforced concrete specimen extend out of the corresponding notches of the salt solution tank respectively; S44. Seal the notches with sealant; S45. Add an erosive solution to the salt solution tank to ensure that the solution exceeds the height of the reinforced concrete specimen by at least 10 mm, and protect the non-erosion surface and the steel bars extending outside the salt solution tank.

[0016] The present application has the following beneficial effects compared with the prior art:

[0017] 1. In the embodiment of the present application, through two three-point bending loadings and one longitudinal tension loading of the steel bars in the specimen, the prefabrication of a single crack is realized, and the crack width is effectively controlled during the crack prefabrication process. At the same time, through the anti-ion erosion performance test device for concrete with cracks, a continuous axial tensile load is applied to the steel bars in the specimen and an erosion test is carried out. The ion diffusion law and the steel bar corrosion situation obtained in the test can be used for the durability analysis and life prediction of actual engineering structures. Thus, the research purposes such as the influence of crack width on the diffusion of erosion substances and the corrosion of steel bars in reinforced concrete specimens under the coupling action of load and erosion solution can be achieved.

[0018] 2. Compared with the prior art where complex cracks need to consider the influence of various factors such as crack width, depth, and orientation (relative to steel bars), the uniformly wide single crack obtained in the embodiment of the present application is particularly suitable for the research on the durability performance of concrete structures focusing on the single factor of crack width. That is, as long as the crack width is measured by a crack width measuring instrument, the damage situation can be accurately described, which is more convenient for crack measurement, statistics, and calculation, and is more convenient in the theoretical derivation and numerical simulation of the durability of concrete structures.

[0019] 3. The specimen in the present application uses a reinforced concrete structure specimen. Compared with the concrete specimen without steel bars in the prior art, the specimen in the present application not only has the same stress principle as the actual service structure project, but also the steel bars in the specimen can not only play the role of loading and load holding, but also can detect and study the steel bar corrosion situation, which is also an important content of the durability research of reinforced concrete structures.

[0020] 4. The embodiments of the present application can achieve the research on solution immersion or wet-dry cycling erosion of cracked reinforced concrete specimens under continuous axial tensile load, and the salt solution tank in the test device can just be placed in the space formed by the upper and lower support components. This not only makes the structure more compact and the solution replacement more convenient, but also reduces the waste of solution in the test while ensuring that the immersion requirements of the concrete specimens can be fully met. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 Front view of the test device for the anti-ion erosion performance of cracked concrete in the embodiments of the present application;

[0023] Figure 2 Top view of the test device for the anti-ion erosion performance of cracked concrete in the embodiments of the present application;

[0024] Figure 3 Side view of the test device for the anti-ion erosion performance of cracked concrete in the embodiments of the present application;

[0025] Figure 4 Schematic structural diagram of the upper support component in the test device for the anti-ion erosion performance of cracked concrete in the embodiments of the present application;

[0026] Figure 5 Schematic structural diagram of the reinforced concrete specimen in the embodiments of the present application;

[0027] Figure 6 Schematic structural diagram of the salt solution tank in the test device for the anti-ion erosion performance of cracked concrete in the embodiments of the present application;

[0028] Figure 7 Flow chart of the test method in the embodiments of the present application. Detailed Embodiments

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0030] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0031] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; for those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0032] The terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0033] Referring to Figures 1 to 3 , an embodiment of the present application provides a test device for the anti-ion erosion performance of cracked concrete, which includes two upper support assemblies 1, two lower support assemblies 2, and two loading plates 3. Among them, the loading plate 3 is a square steel plate with dimensions of: length × width × height = 200 mm × 200 mm × 25 mm.

[0034] The two loading plates 3 are arranged in parallel, and a first through hole and four second through holes are provided on the loading plate 3. The first through hole is located at the center of the loading plate 3, and the four second through holes are respectively arranged near the four vertices of the loading plate 3. Both ends of the upper support assembly 1 and the lower support assembly 2 are mounted at the second through holes. Specifically, referring to Figure 4 , the upper support assembly 1 includes a lead screw 11 and fixing nuts 12 connected to both ends of the lead screw 11. Both ends of the lead screw 11 are mounted at the second through holes, and the fixing nuts 12 are located inside the corresponding loading plate 3. The lower support assembly 2 has the same structure as the upper support assembly 1. The lead screw 11 is a standard lead screw with a diameter of 24 mm and a length of 850 mm. The upper support assembly 1 and the lower support assembly 2 can support the two loading plates 3 and prevent them from approaching each other.

[0035] A salt solution tank 4 for accommodating salt solution is provided between the upper support assembly 1 and the lower support assembly 2. Specifically, a mounting plate 5 is connected to the lower support assembly 2, and the salt solution tank 4 is placed on the mounting plate 5. Referring to Figure 6, the salt solution tank 4 is a rectangular shell with an upward opening.

[0036] Specifically, referring to Figure 2 and Figure 6 , the salt solution tank 4 is made of 3mm thick acrylic board and is cut and assembled by laser cutting technology. The outer edge size of the salt solution tank 4 is 430mm×120mm×150mm, the wall thickness is 3mm, and the actual inner edge size is 424mm×114mm×147mm. Selecting this size can not only meet the requirement of being placed in the internal space formed by the upper and lower support components, but also ensure that the reinforced concrete specimen 6 can be completely immersed. The salt solution tank 4 can be placed inside the load-bearing part by means of the mounting plate 5 placed on the lower support component 2. The mounting plate 5 for placing the salt solution tank 4 is made of a steel plate with a size of 440mm×160mm×3mm. At the corresponding positions of the steel bars at both ends of the salt solution tank 4, a notch 41 needs to be opened respectively. The notch 41 can be a U-shaped groove with a width of 18mm and a depth of 70mm.

[0037] Referring to Figure 5 , the reinforced concrete specimen 6 is a prismatic reinforced concrete specimen, and external thread sections are processed on the steel bars at both ends. Specifically, the size of the reinforced concrete specimen 6 is: length×width×height = 100mm×100mm×400mm. Among them, the through-core steel bar for applying axial tensile load is an HRB400 grade steel bar with a diameter of 16mm and a length of 700mm. The first end of the through-core steel bar is threaded starting from the end point, and the threading length is 30mm. The second end starts threading 130mm away from the end point, and the thread length is 30mm. The designed strength of the concrete is C40.

[0038] Referring to Figure 2 , during the anti-ion erosion performance test, the middle part of the reinforced concrete specimen 6 is located inside the salt solution tank 4. The steel bar at the first end of the reinforced concrete specimen 6 extends out of one notch 41 and the first through-hole in sequence and is fastened to the load-bearing nut 7. The steel bar at the second end extends out of the other notch 41 and the first through-hole in sequence and is connected to the loading nut 8. Moreover, the steel bars at both ends of the reinforced concrete specimen 6 are sealed with the side wall of the salt solution tank 4 by sealant.

[0039] It should be noted that when continuously applying axial tensile load to the reinforced concrete specimen 6, the salt solution tank 4 has not been installed yet. The second end of the reinforced concrete specimen 6 is connected to a tensioning device (not shown in the figure). After the axial tensile load is applied, the salt solution tank 4 is installed, the second end of the reinforced concrete specimen 6 is connected to the loading nut 8, and then the tensioning device is removed. The tensioning device adopts a QYC270 type prestressed through-core front-loading jack (i.e., the tool anchor is placed in front).

[0040] Referring to Figure 7, embodiments of the present application also provide a test method based on the above test device for the anti-ion erosion performance of cracked concrete. This method facilitates the application of a continuous axial tensile load to the specimen by casting a reinforced concrete specimen with steel bars protruding from both ends. Then, the specimen reaching the target age is subjected to two bending loadings and one axial tensile loading to uniformly penetrate the internal and external cracks of the specimen to the steel bars. Next, a constant axial tensile load is applied using the test device for the anti-ion erosion performance of cracked concrete to simulate the stress state of the tensile zone in an actual engineering structure, achieving the goal of controllable crack width during the loading process. A salt solution tank 4 is used in combination for anti-erosion tests with chloride salts, sulfates, etc., which is economical and practical and convenient for solution replacement.

[0041] This method includes the following steps:

[0042] S1. Prepare a reinforced concrete specimen 6; the reinforced concrete specimen 6 is a prismatic reinforced concrete specimen 6, and external thread segments are processed on the steel bars at both ends thereof.

[0043] S2. Prefabricate target uniform cracks; the target uniform cracks are single cracks with uniform width.

[0044] S21. Conduct two three-point bending loadings on the reinforced concrete specimen 6 to obtain preliminary load cracks.

[0045] S211. Define the four formed surfaces of the reinforced concrete specimen 6:

[0046] Evenly brush putty slurry on the four sides of the reinforced concrete specimen 6, and mark a grid with a size of 25 mm × 25 mm on the specimen surface; define the formed surface as the bottom surface, its opposite surface as the front surface, and the rest as side A and side B. For single-sided erosion tests, the front surface is used as the erosion surface.

[0047] S212. Conduct the first three-point bending loading with side B of the specimen as the tensile surface. When the crack on the front surface or the bottom surface extends to 1 / 2 of the depth, stop loading and record the bending moment value M0 at this time.

[0048] S213. Conduct the second three-point bending loading with side A of the specimen as the tensile surface. Stop loading when the bending moment reaches M0 to obtain preliminary load cracks. After unloading, evenly arrange 10 measuring points along the crack direction on the front surface and the bottom surface of the reinforced concrete specimen 6, measure the crack width at each measuring point position, and calculate the average crack width of each surface. If the difference between the average crack widths of the measured front surface and the bottom surface does not exceed 0.04 mm, it is considered that the preliminary production of the load cracks is qualified.

[0049] S22. Apply an axial tensile load to the reinforced concrete specimen 6 to obtain target uniform cracks:

[0050] Apply axial tensile load to the reinforced concrete specimen 6 through a testing machine. After the crack width reaches the target width of 0.2 mm, measure the target crack width at 10 measuring points on the four surfaces and calculate the average crack width of each surface. The difference between the measured values of the inner measuring points on each side does not exceed 0.04 mm, and the difference between the average values of the four sides does not exceed 0.04 mm. At this time, the formed cracks are considered qualified.

[0051] S3. Continuously apply axial tensile load to the reinforced concrete specimen 6 through the anti-ion erosion performance test device for cracked concrete until the target qualified cracks are obtained.

[0052] S31. Assemble the upper support assembly 1, the lower support assembly 2, the reinforced concrete specimen 6, two loading plates 3 and the tensioning equipment to form a tensioning assembly. Among them, the tensioning equipment is connected to the second end of the reinforced concrete specimen 6. The tensioning equipment uses a QYC270 type prestressed through-hole front-loading jack (i.e., the tool anchor is placed in front).

[0053] S32. Operate the tensioning equipment to apply a stable load to the reinforced concrete specimen 6 until the loading is stopped after reaching the target qualified crack width:

[0054] Specifically, stop loading immediately when the oil pressure of the tensioning equipment reaches the oil pressure corresponding to the expected crack width.

[0055] After the cracks are made, measure the target crack width at the measuring points on the four sides and calculate the average crack width of each side. The difference between the measured values of the inner measuring points on each side does not exceed 0.04 mm, and at the same time, the difference between the average values of the four sides does not exceed 0.04 mm. At this time, the obtained cracks are considered qualified.

[0056] S33. Fasten the holding nut 7 at the front end of the tensioning equipment to the steel bars at the end of the reinforced concrete specimen 6, and unload the tensioning equipment.

[0057] S4. Conduct an anti-ion erosion performance test on the reinforced concrete specimen 6 through the anti-ion erosion performance test device for cracked concrete.

[0058] S41. Place the tensioning assembly in step S31 horizontally.

[0059] S42. Measure the target qualified crack width with a crack width gauge. Take the crack width distribution measured this time as the final test crack width level, and record the maximum crack width of each measuring point and the average crack width of each target erosion surface.

[0060] S43. Install the salt solution tank 4 to ensure that the middle part of the reinforced concrete specimen 6 is located inside the salt solution tank 4, and the steel bars at both ends of the reinforced concrete specimen 6 extend out of the corresponding notches 41 of the salt solution tank 4 respectively:

[0061] Place the mounting plate 5 on the two lower support components 2, and then place the salt solution tank 4 on the mounting plate 5, ensuring that the notch 41 exactly engages with the steel bars protruding from the reinforced concrete specimen 6.

[0062] S44. Seal the notch 41 with sealant; the sealant can be epoxy resin glue.

[0063] S45. Add corrosive solution, such as 5% NaCl solution, into the salt solution tank 4, and ensure that the corrosive solution exceeds the height of the reinforced concrete specimen 6 by at least 10 mm, and protect the non-corrosive surface and the steel bars protruding outside the salt solution tank 4.

[0064] S5. After the anti-ion corrosion performance test is completed, unload the reinforced concrete specimen 6, and detect the damage condition of the concrete and the corrosion condition of the steel bars:

[0065] After reaching a certain test age, remove the salt solution tank 4, and use a wrench to slowly loosen the loading nut 8 and the holding nut 7 in turn to unload the reinforced concrete specimen 6. At this time, one loading plate 3 can be removed, and after taking out the reinforced concrete specimen 6, the damage condition of the concrete and the corrosion condition of the steel bars of this specimen can be detected.

[0066] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any change or replacement within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An experimental device for the anti-ion erosion performance of cracked concrete, characterized in that it includes an upper support assembly, a lower support assembly and two loading plates; The two loading plates are arranged in parallel, and a first through hole and a plurality of second through holes are provided on the loading plates; the first through hole is located at the center of the loading plate, and the plurality of second through holes are all located on the outer periphery of the first through hole; both ends of the upper support assembly and the lower support assembly are erected at the second through holes; the upper support assembly and the lower support assembly can prevent the two loading plates from approaching each other; a salt solution tank for accommodating salt solution is provided between the upper support assembly and the lower support assembly; the middle part of the reinforced concrete specimen is located in the salt solution tank, the steel bar at the first end of the reinforced concrete specimen extends out of one of the first through holes and is fastened to the holding nut, and the steel bar at the second end extends out of the other first through hole and is fastened to the loading nut; the reinforced concrete specimen is a quadrangular prism reinforced concrete specimen, and external thread segments are processed on the steel bars at both ends thereof; The test method based on the experimental device for the anti-ion erosion performance of cracked concrete includes the following steps: S1. Prepare a reinforced concrete specimen; S2. Prefabricate a target uniform crack, and the target uniform crack is a single crack with uniform width; S21. Perform two-point three-point bending loading on the reinforced concrete specimen to obtain a preliminary load crack; S22. Apply axial tensile load to the reinforced concrete specimen to obtain the target uniform crack; S3. Continuously apply axial tensile load to the reinforced concrete specimen through the experimental device for the anti-ion erosion performance of cracked concrete until a target qualified crack is obtained; S4. Perform an anti-ion erosion performance test on the reinforced concrete specimen through the experimental device for the anti-ion erosion performance of cracked concrete; S5. After the anti-ion erosion performance test is completed, unload the reinforced concrete specimen, and detect the damage condition of the concrete and the corrosion condition of the steel bars.

2. The test device for the anti-ion erosion performance of cracked concrete according to claim 1, wherein, The loading plate is a square plate, there are two upper support assemblies and two lower support assemblies, and the two upper support assemblies and the two lower support assemblies are respectively arranged close to the corresponding vertices of the loading plate.

3. The test device for the anti-ion erosion performance of cracked concrete according to claim 1, characterized in that, The upper support assembly includes a lead screw and fixed nuts connected to both ends of the lead screw, and the fixed nuts are located inside the corresponding loading plates; the lower support assembly has the same structure as the upper support assembly.

4. The test device for the anti-ion erosion performance of cracked concrete according to claim 1, characterized in that An installation plate is provided on the lower support assembly, and the salt solution tank is arranged on the installation plate.

5. The test device for the anti-ion erosion performance of cracked concrete according to claim 1, characterized in that, The salt solution tank is a rectangular shell with an upward opening, and notches are provided on the two side walls in the length direction of the rectangular shell. The steel bars at both ends of the reinforced concrete specimen extend out of the corresponding notches and second through holes in sequence and are respectively fastened to the holding nut and the loading nut, and the steel bars at both ends of the reinforced concrete specimen are sealed with the side walls of the salt solution tank through sealant.

6. The test device according to claim 1, characterized in that The S21 includes the following steps: S211. Define the four formed surfaces of the reinforced concrete specimen: Define the formed surface as the bottom surface, its opposite surface as the front surface, and the rest as the A side surface and the B side surface; S212. Conduct the first three-point bending load on the side surface of Specimen B as the tensile surface. When the crack on the front or bottom surface extends to the preset depth, stop the load and record the bending moment value at this time. S213. Conduct the second three-point bending load on the side surface of Specimen A as the tensile surface. Stop the load when the bending moment reaches the bending moment value in S212 to obtain the preliminary load crack.

7. The test device according to claim 1, characterized in that The said S3 includes the following steps: S31. Assemble the upper support assembly, lower support assembly, reinforced concrete specimen, two loading plates and the tensioning equipment to form a tensioning assembly. S32. Operate the tensioning equipment to conduct a stable load on the reinforced concrete specimen until the load stops when the target qualified crack width is reached. S33. Fasten the holding nut at the front end of the tensioning equipment to the steel bars at the end of the reinforced concrete specimen, and unload the tensioning equipment.

8. The test device according to claim 7, characterized in that, The said S4 includes the following steps: S41. Horizontally place the tensioning assembly in step S33. S42. Measure the target qualified crack width with a crack width gauge. Take the crack width distribution measured this time as the final test crack width level, and record the maximum crack width at each measuring point and the average crack width of each target erosion surface. S43. Install the salt solution tank to ensure that the middle part of the reinforced concrete specimen is located inside the salt solution tank, and the steel bars at both ends of the reinforced concrete specimen extend out of the corresponding notches of the salt solution tank respectively. S44. Seal the notches with sealant. S45. Add the erosive solution into the salt solution tank to ensure that the solution exceeds the height of the reinforced concrete specimen by at least 10 mm, and protect the non-erosion surface and the steel bars extending outside the salt solution tank.

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