Device and method for testing corrosion resistance of pavement steel for bridge and method for evaluating corrosion resistance

Abstract

The invention belongs to the technical field of steel plate corrosion evaluation, and particularly relates to a bridge pavement steel corrosion resistance testing device and method and a corrosion resistance evaluation method.The method comprises the steps that 1, a sample holder is rotated, so that one face of a to-be-tested sample fixed to the sample holder faces upwards, and simulation liquid for simulating the atmospheric environment is sprayed to the upward face; when the other side of the test sample faces downwards, heating and drying are performed, and the other side of the test sample is dried; 2) rotating the sample holder to enable the other side of the to-be-tested sample to face upwards, and spraying the simulated concrete pore liquid to the to-be-tested sample; one side of the to-be-tested sample faces downwards, heating and drying are performed, and one side of the sample is dried; and (3) repeating the steps (1) and (2), and alternately spraying the simulated liquid for simulating the atmospheric environment and the simulated concrete pore liquid. The device has the advantages that the working environment of the pavement steel can be simulated, the corrosion test of the pavement steel in two environments can be simultaneously carried out without two corrosion tests, the test process is simplified, and the test accuracy is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel plate corrosion evaluation, and particularly relates to a corrosion resistance test device and method for bridge pavement steel, and a corrosion resistance evaluation method. Background Art

[0002] With the progress of science and technology in China, the rapid development of industry and agriculture, and the increasingly active urban-rural exchanges, the road traffic volume has increased significantly. Large buses and heavy trucks have also increased day by day. Coupled with traffic congestion caused by the growth of traffic volume and the frequent braking and starting of vehicles, higher requirements are put forward for the service performance of road pavements. From the current development status at home and abroad, although the cost of traditional asphalt concrete pavements is not high, their service life is short and the maintenance cost is high. In recent years, in some countries with developed highway transportation, such as the United States, Germany, etc., the development of bridge pavement steel plates has been very rapid.

[0003] When the bridge pavement steel plate is in service, the upper and lower surfaces of the steel plate are respectively in the atmospheric and concrete environments, resulting in rust damage on the upper and lower surfaces during long-term use and shortening the service life of the bridge pavement steel.

[0004] For corrosion test devices and methods for simulating the atmospheric environment, the commonly used indoor acceleration methods at present are:

[0005] 1. Salt spray test: An accelerated test method used to evaluate the corrosion resistance of metal materials and the protective effect of coatings on the base metal. This method cannot predict the service life of metal materials in the service environment, but as a classic accelerated test method, it still has certain significance.

[0006] 2. Damp heat test: Often used to evaluate the corrosion resistance of metal materials or the influence of surface residual pollutants. This method is divided into two types: constant damp heat test and alternating damp heat test, and can be used to simulate the high temperature and high humidity environment in the tropics. Since the water droplets formed on the surface during the damp heat test are usually of different sizes and cannot agglomerate and flow, the formed water film is not uniform enough and the simulation is poor.

[0007] 3. Periodic immersion corrosion test: An accelerated test method commonly used at home and abroad, which makes the test piece undergo dry-wet cycles periodically, reproducing the three corrosion states of immersion, wetting, and drying on the metal surface, and is often used for predicting the corrosion life in the atmospheric environment.

[0008] The commonly used acceleration methods for concrete environment corrosion at present are:

[0009] Preparation of concrete test blocks: As specified in the national standard GB / T 31933-2015, a method for evaluating the chloride ion corrosion resistance of steel bars in concrete structures under simulated marine environments is provided. Place the steel bars in a mold to prepare reinforced concrete specimen blocks. After curing and maintenance, inject sodium chloride solution and conduct potential measurements, while recording the surface corrosion conditions of the steel bars. Corresponding dry-wet alternate corrosion tests under simulated seawater environments can also be carried out as needed.

[0010] Method for simulating concrete pore solution: Since the corrosion of reinforced concrete components is slow in natural environments, to simplify the influence of external corrosion environments on reinforced concrete, many researchers have used the preparation of simulated concrete pore solution as an accelerating solution to conduct electrochemical tests and corresponding coupon tests. For example, in the patent publication number: CN106556564A, a method for evaluating the corrosion resistance of steel bars for concrete is disclosed, where electrochemical tests are carried out in simulated concrete pore solution, and the relative corrosion resistance index NSZS of the steel bars is defined, and the corrosion performance of the steel bars is evaluated based on the magnitude of NSZS.

[0011] The above methods all separately study the corrosion performance in the atmospheric environment or the concrete environment, and are not applicable to the study of the corrosion performance of bridge pavement steel where the upper and lower surfaces are respectively in the composite environment of the atmosphere and concrete. Combining the current corrosion test methods in the atmospheric and concrete environments, there is an urgent need to develop a corrosion test method that can simulate the special service environment of bridge pavement steel and can evaluate the corrosion resistance. Summary of the Invention

[0012] To overcome the deficiencies of the prior art, the purpose of the present invention is to provide a corrosion resistance test device and method for bridge pavement steel and a corrosion resistance evaluation method, which can simultaneously simulate the upper and lower surfaces of bridge pavement steel being respectively in the atmospheric environment and the concrete composite environment, and can evaluate the corrosion resistance of bridge pavement steel in this environment.

[0013] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0014] A corrosion resistance test method for bridge pavement steel includes the following steps:

[0015] 1) Fix the test specimen on a rotatable specimen rack;

[0016] 2) Rotate the specimen rack to make one side of the test specimen face upward, and spray the simulation liquid simulating the atmospheric environment on the upward side; the other side of the test specimen faces downward, and is heated and dried, and the other side of the specimen is dried;

[0017] 3) Rotate the specimen rack to make the other side of the test specimen face upward, and spray the simulated concrete pore solution on it; one side of the test specimen faces downward, and is heated and dried, and one side of the specimen is dried;

[0018] 4) Repeat steps 2) and 3), and alternately spray the simulated liquid for simulating the atmospheric environment and the simulated concrete pore liquid.

[0019] The temperature of the simulated liquid for simulating the atmospheric environment is 30 - 60 °C; the spraying pressure is 0.5 - 2 MPa, and the single spraying time of the simulated liquid for simulating the atmospheric environment and the simulated concrete pore liquid is 1 - 180 min; the drying temperature is 40 - 80 °C.

[0020] The simulated atmospheric environment is a simulated marine atmospheric environment, and the simulated liquid for simulating the marine atmospheric environment is a NaCl solution with a mass fraction of 0.5% - 2%; the simulated concrete pore liquid under the marine atmospheric environment is a mixed liquid of a NaCl solution with a mass fraction of 0.1% - 1% and a saturated Ca(OH)₂ solution.

[0021] The simulated atmospheric environment is a simulated industrial atmospheric environment, and the simulated liquid for simulating the industrial atmospheric environment is a NaHSO₃ solution with a concentration of 0.01 - 0.05 mol / L; the simulated concrete pore liquid under the simulated industrial atmospheric environment is a mixed liquid of 1 - 3 g / L CO₃ 2- + 2 - 10 g / L SO₄ 2- + saturated Ca(OH)₂.

[0022] The simulated atmospheric environment is a simulated rural atmospheric environment, and the simulated liquid for simulating the rural atmospheric environment is deionized water; the simulated concrete pore liquid under the simulated rural atmospheric environment is a saturated Ca(OH)₂ solution.

[0023] A corrosion resistance test device for the pavement steel of a bridge, comprising a box body, a specimen rack, a spraying mechanism, a storage tank I, a storage tank II, a heating and drying pipe, a fan, and a solution discharge port; a specimen rack is connected in the middle of the box body, and the box body is divided into an upper area and a lower area by the specimen rack. The upper area is connected with a spraying mechanism, and the lower area is fixedly connected with a heating and drying pipe; the spraying mechanism is provided with spraying liquid by the storage tank I and the storage tank II; the fan is arranged in the upper area, and the bottom of the box body is connected with a solution discharge port; the specimen rack can be driven to rotate by a motor.

[0024] It further includes pipelines, inlet valves, and inlet water pumps. Both the storage tank I and the storage tank II are connected with inlet valves, and the inlet valves are connected with the spraying mechanism through pipelines, and inlet water pumps are connected to the pipelines; the storage tank I and the storage tank II are respectively filled with the simulated liquid for simulating the atmospheric environment and the simulated concrete pore liquid.

[0025] The specimen rack includes a fixed rod, and the end of the fixed rod is connected with the output shaft of the motor through a coupling, and the fixed rod is fixedly connected with the specimen through bolts.

[0026] The upper area is connected with a hygrometer, and the lower area is connected with a thermometer.

[0027] A method for evaluating the corrosion resistance of pavement steel for bridges includes the following steps:

[0028] 1) Calculate the weight loss rate of the pavement steel for bridges after the test:

[0029]

[0030] In formula (1), W 前 is the weight of the specimen before the test, in g; W 后 is the weight of the specimen after the test, in g; S is the total surface area of the specimen, in m 2 , t is the test time, in h; the weight loss rate is the corrosion rate, in g / (m 2 ·h);

[0031] 2) Calculate the pitting corrosion difference degree of the pavement steel for bridges in the atmospheric environment and the concrete environment:

[0032] Divide a same - area region on one side and the other side of the specimen respectively, and measure the depth of the pitting corrosion pits; measure the depth of M pitting corrosion pits on one side of the specimen, denoted as QA, QB, QC......QM, where QA>QB>QC......>QM; measure the depth of m pitting corrosion pits on the other side of the specimen, denoted as Qa, Qb, Qc......Qm, where Qa>Qb>Qc......>Qm;

[0033] Calculate respectively If the calculated value is greater than or equal to 0.25, it is determined that the pitting corrosion difference degree of the corresponding two positions is large, and record the number of large pitting corrosion difference degrees as I;

[0034] According to Calculate the pitting corrosion difference degree between one side and the other side of the pavement steel for bridges;

[0035] 3) Use the weight loss rate and the pitting corrosion difference degree as the indexes for evaluating the corrosion resistance of the pavement steel for bridges, and divide the corrosion resistance into 4 evaluation grades:

[0036] When the weight loss rate > 10.5 g / (m 2 ·h) and the pitting corrosion difference degree > 40%, the corrosion resistance of the pavement steel for bridges is at the severe level;

[0037] When the weight loss rate is 7.5 - 10.5 g / (m 2 ·h) and the pitting corrosion difference degree is 30% - 40%, the corrosion resistance of the pavement steel for bridges is at the relatively severe level;

[0038] When the weight loss rate is 3.5 - 7.5 g / (m 2 ·h), excluding 7.5 g / (m 2·h), and the pitting difference degree is 20% - 30%, excluding 30%, then the corrosion resistance of the bridge pavement steel is medium level;

[0039] When the weight loss rate is 2.0 - 3.5 g / (m 2 ·h), excluding 3.5 g / (m 2 ·h), and the pitting difference degree is 10% - 20%, excluding 20%, then the corrosion resistance of the bridge pavement steel is slightly level;

[0040] When the weight loss rate < 2.0 g / (m 2 ·h), and the pitting difference degree < 10% - 20%, then the corrosion resistance of the bridge pavement steel is relatively slightly level.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] The present invention can simulate the working environment of bridge pavement steel, and can carry out the corrosion tests of bridge pavement steel in two environments simultaneously without conducting two corrosion tests, simplifying the test process and improving the test accuracy. The test device has a simple and reasonable structure, is easy to operate, and has low manufacturing and operation costs, and can meet the requirements of simulating the corrosion resistance performance test of bridge pavement steel. After the corrosion test, taking into account the corrosion weight loss rate of the bridge pavement steel and the pitting difference degree of the two surfaces, the corrosion degree of the bridge pavement steel in this environment can be quantitatively evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is the structural schematic diagram of the present invention.

[0044] Figure 2 is the structural schematic diagram of the baffle.

[0045] In the figure: 1, box body; 2, pipeline; 3, water inlet valve; 4, water inlet pump; 5, specimen rack; 6, storage tank I; 7, storage tank II; 8, heating and drying pipe; 9, solution discharge port; 10, thermometer; 11, hygrometer; 12, specimen; 13, control system; 14, spraying mechanism; 15, fan; 16, baffle; 17, water guiding hole; 18, sealing ring; 19, mounting hole. DETAILED DESCRIPTION OF THE INVENTION

[0046] The present invention will be described in detail below with reference to the accompanying drawings of the specification, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0047] See Figure 1 , a corrosion resistance performance test device for bridge pavement steel that simultaneously simulates different corrosion environments on the upper and lower surfaces of bridge pavement steel, including a box body, a specimen rack, a spraying mechanism, a pipeline, a water inlet valve, a water inlet pump, a storage tank I, a storage tank II, a heating and drying pipe, and a control system;

[0048] The box body is divided into an upper area and a lower area by a specimen rack. A spraying mechanism is connected to the upper area, and a heating and drying pipe (electric heating pipe) is fixedly connected to the lower area. The spraying mechanism is connected to storage tank Ⅰ and storage tank Ⅱ through pipelines, enabling the spraying function. Both storage tank Ⅰ and storage tank Ⅱ are connected with water inlet valves. The water inlet valves are connected to the spraying mechanism through pipelines, and a water inlet pump is connected to the pipelines to adjust the spraying time, spraying flow rate, and spraying pressure. Simulated liquid simulating the atmospheric environment and simulated concrete pore liquid are respectively contained in storage tank Ⅰ and storage tank Ⅱ. Storage tank Ⅰ and storage tank Ⅱ are connected with a heating mechanism to adjust the temperature inside the tanks. The heating and drying pipe can achieve the function of drying and heating, enabling the surface of the specimen to be dried. A waste liquid discharge port is provided at the bottom of the box body for collecting and discharging waste liquid.

[0049] The specimen rack in the middle of the box body is of a flip - type structure. The specimen rack includes a fixed rod. The end of the fixed rod is connected to the output shaft of the motor through a coupling, and the fixed rod is fixedly connected to the specimen through bolts. Multiple specimens of bridge pavement steel plates can be installed on the fixed rod at the same time. The specimen rack can make the upper and lower surfaces of the specimen alternately flip by 180°, with alternate spraying and drying. One side of the bridge pavement steel plate specimen is surface A, and the other side opposite to surface A is surface B. When surface A of the specimen faces upward and surface B faces downward, the heating and drying pipe is in the heating state, the water inlet valve and the water inlet pump are started, and the simulated liquid simulating the atmospheric environment in storage tank Ⅰ is pumped. At this time, surface A of the specimen is sprayed, and at the same time, surface B of the specimen is dried. When the specimen rack flips 180°, surface B of the specimen faces upward, the water inlet valve and the water inlet pump are started, and the simulated concrete pore liquid in storage tank Ⅱ is pumped. At this time, surface A of the specimen is dried. After the upper and lower surfaces of the specimen are sprayed with solutions in their respective different simulated corrosion environments, when it flips to the lower surface, it will be dried, and the two surfaces of the specimen alternately undergo dry - wet cycles. See Figure 2 On the specimen rack, a baffle 16 is fixedly connected through bolts. Several holes for installing the specimen 12 are provided on the baffle 16. Sealing rings 18 are installed around the holes, and the specimen 12 is installed in the holes. Several water guiding holes 17 are provided on the baffle 1 on the outside of the sealing ring 18, which can lead out the corrosive liquid sprayed on the baffle 16. Installation holes are provided on the baffle 16 for fixed connection with the specimen rack. When one side of the specimen 12 is sprayed, under the action of the baffle 16, the other side of the specimen 12 will not be wetted by the flowing corrosive liquid, ensuring that one side of the test piece always contacts only one kind of corrosive liquid.

[0050] A hygrometer and a fan are connected to the upper area of the box body, and a thermometer is connected to the lower area for the regulation and control of temperature and humidity. The control system is used to control and adjust the temperature of the spraying solution in storage tank Ⅰ and storage tank Ⅱ, the spraying time, the spraying flow rate, the flipping time of the specimen rack, the temperature and humidity, etc.

[0051] A test method for the corrosion resistance of bridge pavement steel includes the following steps:

[0052] 1) The sample to be tested is fixed on a rotatable sample holder;

[0053] 2) Rotate the sample holder so that one side of the sample to be tested faces upward, and spray a simulated liquid simulating the atmospheric environment onto the upward-facing side; the other side of the sample to be tested faces downward, and it is heated and dried, and the other side of the sample is dried;

[0054] 3) Rotate the sample holder so that the other side of the sample to be tested faces upward, and spray simulated concrete pore liquid onto it; one side of the sample to be tested faces downward, and it is heated and dried, and one side of the sample is dried;

[0055] 4) Repeat steps 2) and 3), and alternately spray the simulated liquid simulating the atmospheric environment and the simulated concrete pore liquid;

[0056] The temperature of the simulated liquid simulating the atmospheric environment is 30 - 60 °C; the spraying flow rate is 0.5 - 2 MPa, and the single spraying time of the simulated liquid simulating the atmospheric environment and the simulated concrete pore liquid is 1 - 180 min; the drying temperature is 40 - 80 °C.

[0057] It can simulate marine atmospheric environment, industrial atmospheric environment and rural atmospheric environment, and corresponding simulated liquids can be filled in storage tank I and storage tank II according to simulation needs:

[0058] When the simulated atmospheric environment is a simulated marine atmospheric environment, the simulated liquid for the simulated marine atmospheric environment is a NaCl solution with a mass fraction of 0.5% - 2%; the simulated concrete pore liquid under the marine atmospheric environment is a mixed liquid of a NaCl solution with a mass fraction of 0.1 - 1% and a saturated Ca(OH)2 solution.

[0059] When the simulated atmospheric environment is a simulated industrial atmospheric environment, the simulated liquid for the simulated industrial atmospheric environment is a NaHSO3 solution with a concentration of 0.01 - 0.05 mol / L; the simulated concrete pore liquid under the simulated industrial atmospheric environment is 1 - 3 g / L CO3 2- + 2 - 10 g / L SO4 2- + a mixed liquid of saturated Ca(OH)2.

[0060] When the simulated atmospheric environment is a simulated rural atmospheric environment, the simulated liquid for the simulated rural atmospheric environment is deionized water; the simulated concrete pore liquid under the simulated rural atmospheric environment is a saturated Ca(OH)2 solution.

[0061] A method for evaluating the corrosion resistance of pavement steel for bridges includes the following steps:

[0062] 1) Calculate the weight loss rate of the pavement steel for bridges after the test is completed:

[0063]

[0064] In formula (1), W 前is the weight of the specimen before the test, in g; W 后 is the weight of the specimen after the test, in g; S is the total surface area of the specimen, in m 2 , t is the test time, in h; the weight loss rate is the corrosion rate, in g / (m 2 ·h);

[0065] 2) Calculate the pitting corrosion difference degree of the pavement steel for bridges in the atmospheric environment and the concrete environment:

[0066] Divide a same - area region on one side and the other side of the specimen respectively, and measure the depth of the pitting corrosion pits; measure the depth of M pitting corrosion pits on one side of the specimen, denoted as QA, QB, QC......QM, where QA>QB>QC......>QM; measure the depth of m pitting corrosion pits on the other side of the specimen, denoted as Qa, Qb, Qc......Qm, where Qa>Qb>Qc......>Qm;

[0067] Calculate respectively If the calculated value is greater than or equal to 0.25, it is determined that the pitting corrosion difference degree of the corresponding two positions is large, and record the number of positions with large pitting corrosion difference degree as I;

[0068] According to Calculate the pitting corrosion difference degree between one side and the other side of the pavement steel for bridges;

[0069] 3) Use the weight loss rate and the pitting corrosion difference degree as the indexes for evaluating the corrosion resistance of the pavement steel for bridges, and divide the corrosion resistance into 4 evaluation grades, as shown in Table 1.

[0070] Table 1 Corrosion evaluation of the pavement steel for bridges

[0071]

[0072] Example 1

[0073] Use the corrosion resistance test device for the pavement steel for bridges to conduct a corrosion test under the simulated rural - atmospheric environment, and evaluate the corrosion degree, so as to compare its corrosion resistance.

[0074] (1) After degreasing and cleaning the specimen, polish the surface and fix the pavement steel plate specimen for bridges horizontally on the specimen rack with insulated fine wires.

[0075] (2) Fill deionized water in storage tank I as the corrosion liquid for the simulated rural - atmospheric environment; fill clarified saturated Ca(OH)2 in storage tank II as the simulated concrete pore liquid.

[0076] (3) Set parameters through the control system, with the solution temperature at 40 °C, the spraying pressure at 0.5 MPa, and the drying temperature at 50 °C. The spraying time of the solution in the simulated rural atmosphere is 40 min. During the spraying of the solution in the simulated rural atmosphere, the specimen rack is flipped to the A side facing up. The spraying time of the simulated concrete pore solution is 20 min. During the spraying of the simulated concrete pore solution, the specimen rack is flipped to the B side facing up. The spraying of the two solutions is carried out alternately.

[0077] (4) After the 240-hour corrosion test is completed, first calculate the weight loss rate of the material. The weight loss rate is calculated according to the formula: In the formula, W 前 is the weight of the specimen before the test, in grams; W 后 is the weight of the specimen after the test, in grams; S is the total area of the specimen, in m 2 ; t is the test time, in hours; the unit of the weight loss rate is g / (m 2 ·h). The results are shown in Table 2.

[0078] (5) Next, calculate the pitting corrosion difference degree of the bridge pavement steel in the two environments: Divide a region with the same area size on the A side (simulating the rural atmosphere corrosion surface) and the B side (simulating the concrete surface) of the specimen, and measure the depth of the pitting corrosion pits. Measure the depth of 10 pitting corrosion pits (in μm) on the A side. The depth of the corrosion pits is expressed as Q A、 Q B、 Q C ......Q 10 , where Q A >Q B >Q C ......>Q 10 ; Measure the depth of 10 pitting corrosion pits (in μm) on the B side. The depth of the corrosion pits is expressed as Q a、 Q b、 Q c ......Q 10 , where Q a >Q b >Q c ......>Q 10 .

[0079] According to calculate. If the calculation is greater than or equal to 0.25, it is determined that the pitting corrosion difference degree at these two positions is relatively large, and record the number of positions with a relatively large pitting corrosion difference degree as I. Calculate the pitting corrosion difference degree between the A side (simulating the rural atmosphere corrosion surface) and the B side (simulating the concrete surface) of the bridge pavement steel according to the formula . Take into account both the weight loss rate and the pitting corrosion difference degree between the two sides, and evaluate the corrosion degree according to Table 1. The results are shown in Table 2.

[0080] Table 2 Corrosion Results and Degree Grades

[0081] Specimen <![CDATA[Weight loss rate g / (m 2 ·h)]]> Pitting difference % Corrosion degree grade 1# 8.53 35％ Relatively severe 2# 4.62 20％ Medium 3# 1.87 9％ Relatively slight

[0082] The weight loss rate and the degree of pitting difference between two surfaces are taken into account as the indexes for evaluating the corrosion resistance of the pavement steel for bridges, and the corrosion degree grade is evaluated according to Table 1. According to the test results this time, the corrosion resistance from strong to weak is: 3# > 2# > 1#.

[0083] Example 2:

[0084] Use the corrosion test device for pavement steel for bridges to conduct corrosion tests under simulated rural atmospheric environment and evaluate the corrosion degree, so as to compare its corrosion resistance.

[0085] (1) After degreasing, defatting and cleaning the specimen, polish the surface and fix the specimen horizontally on the specimen rack with insulated thin wires.

[0086] (2) Load 0.01mol / L NaHSO3 into storage tank I to simulate the industrial atmospheric environment corrosion solution; load 2g / L CO3 2- +6g / L SO4 2- g / L saturated Ca(OH)2 as the simulated concrete pore solution.

[0087] (3) Set parameters through the control system, the solution temperature is 40°C, the humidity in the box is 60%RH, the spraying pressure is 0.8MPa, and the drying temperature is 70°C. The spraying time of the simulated industrial atmospheric solution is 60min. When spraying the simulated industrial atmospheric solution, the specimen rack is turned over so that the A side is facing up. The spraying time of the simulated concrete pore solution is 30min. When spraying the simulated concrete pore solution, the specimen rack is turned over so that the B side is facing up. The spraying of the two solutions is carried out alternately.

[0088] (4) After 360h of corrosion test, first calculate the weight loss rate of the material. The weight loss rate is calculated according to the formula: The calculation results are shown in Table 3.

[0089] (5) Next, calculate the degree of pitting difference of the pavement steel for bridges in the two environments: Divide a region with the same area size on the A side (simulating the industrial atmospheric corrosion surface) and the B side (simulating the concrete surface) of the specimen, and measure the depth of the pitting pits. Measure the depth of 10 pitting pits (unit: μm) on the A side. The depth of the corrosion pits is expressed as Q A、 Q B、 Q C ......Q 10 where Q A >Q B >Q C ......>Q 10Measure the depth (in μm) of 10 pitting corrosion pits on the B side. The depth of the corrosion pits is denoted as Q a、 Q b、 Q c ......Q 10 , where Q a >Q b >Q c ......>Q 10 .

[0090] According to calculate. If the calculation is greater than or equal to 0.25, it is determined that the pitting corrosion difference degree at these two positions is relatively large, and record the number of positions with relatively large pitting corrosion difference degree as I. According to the formula Calculate the pitting corrosion difference degree between the A side (simulating the rural atmospheric corrosion surface) and the B side (simulating the concrete surface) of the pavement steel for bridges. Take into account both the weight loss rate and the pitting corrosion difference degree between the two sides, and evaluate the corrosion degree according to Table 1. The results are shown in Table 3

[0091] Table 3 Corrosion Results and Degree Grades

[0092] Specimen <![CDATA[Weight loss rate g / (m 2 ·h)]]> Pitting difference % Corrosion degree grade 4# 4.25 30％ Medium 5# 3.42 35％ Relatively severe 6# 1.69 8％ Slight

[0093] Take into account both the weight loss rate and the pitting corrosion difference degree between the two sides as the index for evaluating the corrosion resistance of the pavement steel for bridges, and evaluate the corrosion degree grade according to Table 1. According to the results of this test, the corrosion resistance from strong to weak is: 6# > 4# > 5#

Claims

1. A test method for the corrosion resistance of pavement steel, characterized in that, It includes the following steps: 1) Fix the test sample on a rotatable sample holder; 2) Rotate the sample holder to make one side of the test sample face upward, and spray a simulated liquid simulating the atmospheric environment onto the upward-facing side; the other side of the test sample faces downward, and heating and drying are carried out, and the other side of the sample is dried; 3) Rotate the sample holder to make the other side of the test sample face upward, and spray a simulated concrete pore solution onto it; one side of the test sample faces downward, and heating and drying are carried out, and one side of the sample is dried; 4) Repeat steps 2) and 3), and alternately spray the simulated liquid simulating the atmospheric environment and the simulated concrete pore solution.

2. The test method for the corrosion resistance of pavement steel according to claim 1, characterized in that, The temperature of the simulated liquid simulating the atmospheric environment is 30 - 60 °C; the spraying pressure is 0.5 - 2 MPa, and the single spraying time of the simulated liquid simulating the atmospheric environment and the simulated concrete pore solution is 1 - 180 min; the drying temperature is 40 - 80 °C.

3. The test method for the corrosion resistance of pavement steel according to claim 1, characterized in that, The simulated atmospheric environment is a simulated marine atmospheric environment, and the simulated liquid for the simulated marine atmospheric environment is a NaCl solution with a mass fraction of 0.5% - 2%; the simulated concrete pore solution under the marine atmospheric environment is a mixed solution of a NaCl solution with a mass fraction of 0.1% - 1% and a saturated Ca(OH)₂ solution.

4. A test method for the corrosion resistance of pavement steel according to claim 1, characterized in that The simulated atmospheric environment is a simulated industrial atmospheric environment, and the simulated liquid for simulating the industrial atmospheric environment is a 0.01-0.05 mol / L NaHSO3 solution; the simulated concrete pore fluid under the simulated industrial atmospheric environment is 1-3 g / L CO3 2- +2~10g / L SO4 2- + saturated Ca(OH)2 mixture.

5. A method for testing the corrosion resistance of pavement steel according to claim 1, characterized in that, The simulated atmospheric environment is a simulated rural atmospheric environment, and the simulated liquid for the simulated rural atmospheric environment is deionized water; the simulated concrete pore solution under the simulated rural atmospheric environment is a saturated Ca(OH)₂ solution.

6. A pavement steel corrosion resistance test device for implementing the test method described in any one of claims 1-5, characterized in that, It includes a box body, a sample holder, a spraying mechanism, a storage tank I, a storage tank II, a heating and drying pipe, a fan, and a solution discharge port; a sample holder is connected in the middle of the box body, and the box body is divided into an upper area and a lower area by the sample holder. The upper area is connected with a spraying mechanism, and the lower area is fixedly connected with a heating and drying pipe; the spraying mechanism is provided with spraying liquid by the storage tank I and the storage tank II; the fan is arranged in the upper area, and the bottom of the box body is connected with a solution discharge port; the sample holder can be driven to rotate by a motor.

7. An experimental device for the corrosion resistance of pavement steel according to claim 6, characterized in that, It also includes pipelines, water inlet valves, and water inlet pumps. Both the storage tank I and the storage tank II are connected with water inlet valves, the water inlet valves are connected with the spraying mechanism through pipelines, and a water inlet pump is connected to the pipelines; the storage tank I and the storage tank II respectively contain the simulated liquid simulating the atmospheric environment and the simulated concrete pore solution.

8. An experimental device for the corrosion resistance of pavement steel according to claim 6, characterized in that, The sample holder includes a fixed rod, the end of the fixed rod is connected with the output shaft of the motor through a coupling, and the fixed rod is fixedly connected with the sample through bolts.

9. An experimental device for the corrosion resistance of pavement steel according to claim 6, characterized in that, The upper area is connected with a hygrometer, and the lower area is connected with a thermometer.

10. A method for evaluating the corrosion resistance of pavement steel implemented based on the test method described in any one of claims 1-5, characterized in that, It includes the following steps: 1) Calculate the weight loss rate of the pavement steel after the test is completed: In formula (1), W 前 is the weight of the specimen before the test, in g; W 后 is the weight of the test specimen after the test, in g; S is the total surface area of the specimen, in m 2 , t is the test time, in h; the weight loss rate is the corrosion rate, in g / (m 2 ·h); 2) Calculate the pitting corrosion difference degree of the pavement steel in the atmospheric environment and the concrete environment: Divide a same-area region on one side and the other side of the sample respectively, and measure the depth of pitting corrosion pits; measure the depth of M pitting corrosion pits on one side of the sample, denoted as QA, QB, QC... QM, where QA > QB > QC... > QM; measure the depth of m pitting corrosion pits on the other side of the sample, denoted as Qa, Qb, Qc... Qm, where Qa > Qb > Qc... > Qm; Calculate separately If the calculated value is greater than or equal to 0.25, it is determined that the pitting corrosion difference degree between the corresponding two positions is relatively large, and the number of positions with relatively large pitting corrosion difference degree is recorded as I; According to calculate the degree of difference in pitting corrosion between one side and the other side of the pavement steel; 3) Use the weight loss rate and the pitting corrosion difference degree as indexes for evaluating the corrosion resistance of the pavement steel, and divide the corrosion resistance into 4 evaluation grades: When the weight loss rate > 10.5 g / (m 2 ·h), and the pitting corrosion difference degree > 40%, the corrosion resistance of the pavement steel is at a severe level; When the weight loss rate is 7.5 - 10.5 g / (m 2 ·h) and the pitting corrosion difference degree is 30% - 40%, the corrosion resistance of the pavement steel is at a relatively severe level; When the weight loss rate is 3.5 - 7.5 g / (m 2 ·h), excluding 7.5 g / (m 2 ·h), and the degree of pitting corrosion difference is 20% - 30%, excluding 30%, the corrosion resistance of the pavement steel is medium; When the weight loss rate is 2.0 - 3.5 g / (m 2 ·h), excluding 3.5 g / (m 2 ·h), and the pitting corrosion difference degree is 10% - 20%, excluding 20%, the corrosion resistance of the pavement steel is slight; When the weight loss rate < 2.0 g / (m 2 ·h), and the pitting corrosion difference degree < 10% - 20%, the corrosion resistance of the pavement steel is at a relatively slight level.

Images