Testing device for simulating corrosion of stray current to steel fiber reinforced concrete

Abstract

A test device for simulating corrosion of stray current to steel fiber reinforced concrete comprises a direct-current power box and an anti-corrosion box, a sponge piece layer is arranged on the outer layer of a to-be-tested piece, an upper sponge piece is arranged on the top face of the to-be-tested piece, a lower sponge piece is arranged on the bottom face of the to-be-tested piece, the lower sponge piece is located on a titanium mesh, and the titanium mesh is located on the bottom face of an inner cavity of the anti-corrosion box. A graphite plate is placed on the upper sponge piece, and the graphite plate and the titanium mesh piece are connected with the direct-current power box through wires. The testing device is short in testing period, simple, low in cost and capable of effectively simulating corrosion of stray current to the steel fiber reinforced concrete.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of steel fiber reinforced concrete durability test, it is a test device that simulates stray current corrosion of steel fiber reinforced concrete. BACKGROUND

[0002] As a new type of composite material, steel fiber reinforced concrete has excellent mechanical properties and is widely used in subway construction. In subway tunnels, steel fiber reinforced concrete can improve the strength and toughness of the lining, improve the waterproof performance, and prolong the service life. In subway stations, steel fiber reinforced concrete can be used for platform slabs, stairs, and underground continuous walls to withstand pedestrian flow and train vibrations, improve load-bearing capacity, and ensure safety and stability.

[0003] In China, the subway system generally uses direct current traction power supply. In ideal conditions, the power supply current provides power for the locomotive, and then returns to the negative pole of the traction substation through the running rail. In actual conditions, it is difficult to completely insulate the running rail from the ground, and part of the current flows out of the running rail into buried metal structures, forming stray current. Stray current can cause electrochemical corrosion of steel materials such as steel bars and steel fibers in the metal pipes and concrete structures along the subway route. According to engineering experience, the damage of stray current to concrete structures mainly reflects the corrosion of steel. Stray current can accelerate the corrosion process of metal, as it conducts through the soil and pipes, forming a closed circuit around the soil, accelerating the oxidation rate of iron in the anode area. In the subway system, the presence of stray current can cause corrosion of the rail and its accessories, concrete structures, and buried pipelines.

[0004] Seawater intrusion in coastal cities is one of the main reasons for the increase in chloride ion content in groundwater. High chloride ion content in groundwater can cause serious corrosion problems in steel bars in concrete structures. When the corrosion products accumulate to a certain extent, it can cause concrete corrosion expansion and cracking, affecting the service life of the subway project. Existing research shows that there is a positive correlation between chloride ions in groundwater and the distance from the coastline. Therefore, for subway projects in coastal cities, the influence of chloride ions in groundwater should be considered when considering the durability of subway structures.

[0005] The invention patent application with the Chinese patent publication number CN118425012 A discloses a test equipment for the durability of concrete under dry-wet cycles. In order to obtain reliable durability data during the test process and make the test piece achieve the expected erosion effect, the dry-wet cycle test usually needs to be repeated multiple times (several dozen to several hundred times). The entire test may take several weeks or even months to complete, resulting in a long test period and relatively high test and labor costs.

[0006] The utility model discloses a kind of steel reinforced concrete test piece veneering method accelerated corrosion test device, the device for test piece accelerated corrosion method uses traditional veneering method, the device can batch power corrosion test, but the device is bulky, structure is more complex, and use cost is higher.

[0007] In the above prior art, the test period of the concrete wet-dry cycle test is long, and it is difficult to obtain the effect of stray current on steel fiber reinforced concrete corrosion in a short time. In the traditional veneering method, sodium chloride solution is usually used between the contact surfaces of the anode, cathode and test block to ensure the test effect, resulting in a complex test device, large size, increased test difficulty and increased test cost.

[0008] Therefore, it is crucial to find a test method and test device that can effectively simulate the corrosion of stray current on steel fiber reinforced concrete in actual conditions, with short test period, simple test device, low cost and effective simulation of stray current corrosion on steel fiber reinforced concrete. SUMMARY

[0009] To overcome the shortcomings of the prior art, the utility model provides a test device that can effectively simulate the corrosion of stray current on steel fiber reinforced concrete, with short test period, simple test device and low cost.

[0010] The utility model solves the technical problems by adopting the following technical solutions:

[0011] A test device for simulating the corrosion of stray current on steel fiber reinforced concrete, comprising a DC power supply box and a corrosion-resistant box. The outer layer of the test piece has a sponge sheet layer. The top surface of the test piece is a top sponge sheet, and the bottom surface of the test piece is a bottom sponge sheet. The bottom sponge sheet is located on a titanium mesh, and the titanium mesh is located on the inner cavity bottom surface of the corrosion-resistant box. A graphite plate is placed on the top sponge sheet. The graphite plate and the titanium mesh are connected to the DC power supply box through wires.

[0012] Further, the positive electrode of the DC power supply box is connected to the titanium mesh through wires, serving as the anode of the corrosion device. The negative electrode of the DC power supply box is connected to the graphite plate through wires, serving as the cathode of the corrosion device.

[0013] The utility model has the following advantages:

[0014] 1. It can meet the requirements of steel fiber reinforced concrete power corrosion test, and different voltages can be adjusted according to the actual situation of the test.

[0015] 2. The sponge sheet is used instead of the conductive solution in the traditional veneering method, reducing the loss of current during the power corrosion process and improving the efficiency of the test.

[0016] 3. Can be used to study the influence of steel fiber reinforced concrete on material durability under the superimposed action of stray current and different concentrations of NaCl solution.

[0017] 4. Can shorten the steel fiber reinforced concrete corrosion test specimen, and facilitate the durability evaluation of the material by the test personnel within a short period of time. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a structural schematic view of the test device for simulating the corrosion of steel fiber reinforced concrete by stray current.

[0019] The reference signs are as follows: 1. DC power supply box; 2. Graphite plate; 3. Upper sponge sheet; 4. Test piece; 5. Lower sponge sheet; 6. Titanium mesh; 7. Wire; 8. Corrosion-proof box. DETAILED DESCRIPTION

[0020] The utility model will be further described below with reference to the drawings.

[0021] Referring to Figure 1 A test device for simulating the corrosion of steel fiber reinforced concrete by stray current, comprising a DC power supply box 1 and a corrosion-proof box 8, the test piece 4 has a sponge sheet layer on the outer layer, the top surface of the test piece 4 is an upper sponge sheet 3, the bottom surface of the test piece 4 is a lower sponge sheet 5, the lower sponge sheet 5 is located on the titanium mesh 6, the titanium mesh 6 is located on the inner cavity bottom surface of the corrosion-proof box 8, the graphite plate 2 is placed on the upper sponge sheet 3, and the graphite plate 2 and the titanium mesh 6 are connected with the DC power supply box 1 through wires.

[0022] Preferably, the positive electrode of the DC power supply box 1 is connected with the titanium mesh 6 through the wire 7, serving as the anode of the corrosion device, and the negative electrode of the DC power supply box 1 is connected with the graphite plate 2 through the wire, serving as the cathode of the corrosion device.

[0023] The working process of the embodiment is as follows:

[0024] 1. According to the designed mixing ratio, the cement, coarse aggregate, fine aggregate and water are first mixed uniformly in a mixer, and then the steel fiber is added, and the mixture is stirred until the steel fiber is uniformly distributed in the concrete without clumping phenomenon, and then poured into a mold, and the mold is placed in an environment with a temperature of 10℃ or higher and a humidity of 90% or higher for 24 hours, and then demolded and cured to the planned age.

[0025] 2. Prepare a 5% NaCl solution as a conductive solution. This solution simulates the corrosive medium found in underground environments. Before immersion, clean the test piece 4 to remove surface oil and dust to ensure test accuracy. Soak the test piece in the 5% NaCl solution for 24 hours to ensure sufficient moisture on the surface and saturate the internal structure, simulating the corrosive conditions found in a real-world environment.

[0026] 3. Turn off the external power supply. Connect the graphite plate 2 to the negative terminal of the DC power supply box 1 via wire 7. Connect the titanium mesh 6 to the positive terminal of the DC power supply box 1 via wire. Then, place a sponge sheet soaked in 5% NaCl solution between the anode, cathode, and the contact surface of the test piece. Ensure that all connections are secure and reliable to avoid open circuits or short circuits during the test.

[0027] 4. Turn on the DC power supply box 1, set the output voltage value according to the specific requirements of the test (such as corrosion rate) and the characteristics of the material, use the constant voltage mode, and conduct corrosion tests for different corrosion times (such as 48h, 72h) for each group of specimens according to the set corrosion rate. Replace the sponge and replenish the solution every 12h.

[0028] The embodiments of this specification are merely examples of implementations of the invention and are for illustrative purposes only. The scope of protection of this utility model should not be considered limited to the specific forms described in this embodiment. The scope of protection of this utility model also extends to equivalent technical means that can be conceived by ordinary technicians in this field based on the invention.

Claims

1. A test device for simulating the effect of stray current on the corrosion of steel fiber reinforced concrete, characterized by, The test device comprises a direct current power supply box and an anticorrosion box, the outer layer of the test piece has a sponge sheet layer, the top surface of the test piece is a top sponge sheet, the bottom surface of the test piece is a bottom sponge sheet, the bottom sponge sheet is located on a titanium mesh, the titanium mesh is located on the bottom surface of the inner cavity of the anticorrosion box, a graphite plate is placed on the top sponge sheet, and the graphite plate and the titanium mesh are connected with the direct current power supply box through wires.

2. The apparatus for testing the corrosion of steel fiber reinforced concrete by simulating stray current according to claim 1, wherein The positive electrode of the direct current power supply box is connected with the titanium mesh through wires and serves as the anode of the erosion device, and the negative electrode of the direct current power supply box is connected with the graphite plate through wires and serves as the cathode of the erosion device.

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