Test device and test method for simulating actual flowing water scouring behavior of asphalt pavement

Abstract

The invention relates to a test device and a test method for simulating an actual flowing water scouring behavior of an asphalt pavement, and aims to solve the technical problem that the actual flowing water scouring behavior of the asphalt pavement is difficult to simulate in the prior art. The test temperature, the water pressure and the dynamic water scouring time in the dynamic water scouring test process can be accurately adjusted and controlled, factors such as water, temperature and load are coupled, the test environment is close to the actual working condition, the dynamic water scouring action caused by vehicle tires on the actual asphalt pavement surface is truly simulated, and good generalizability is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of road engineering detection, and relates to a test device and a test method for simulating the dynamic water scouring behavior of an actual asphalt pavement. Background Art

[0002] During rainy weather, there will be moisture distribution within a range of 10cm from the road surface. Due to the impermeability of asphalt pavement, moisture will be stored inside the asphalt pavement structure for a long time. When vehicles driving on the road surface squeeze the road surface, dynamic water pressure will be formed. The long-term dynamic water pressure on the asphalt pavement will cause the asphalt adhesion to decrease, causing the asphalt film to peel off, resulting in cracks and damage inside the asphalt pavement structure, and eventually causing looseness, peeling, potholes and other diseases, which seriously reduce the service life of the asphalt pavement.

[0003] my country's current standards use the immersion Marshall test and freeze-thaw splitting test to evaluate the water stability of asphalt mixtures. This is to test the changes in performance indicators of asphalt mixture specimens after curing them with water by immersion or freeze-thaw cycles. This is a static water effect, which is quite different from the dynamic water scouring effect that asphalt pavements are actually subjected to. In order to truly simulate the dynamic water scouring effect that actual asphalt pavements are subjected to, scholars in related fields have designed and developed some dynamic water scouring test devices. However, the inventors of this application found in practical research that these existing test devices still have shortcomings, mainly including: (1) the test does not introduce water pressure; (2) the test temperature and pressure are uncontrollable; (3) the three factors of water, temperature and load are not integrated together.

[0004] The inventor knows a test device for simulating the dynamic water scouring behavior of asphalt mixture (CN 214277768U), which includes a rainfall simulation box and a water supply device; the top of the rainfall simulation box is open, and a sample placement plate and a heating device are arranged in the rainfall simulation box, the sample placement plate is arranged at a distance from the bottom of the rainfall simulation box, and the heating device is arranged between the sample placement plate and the bottom of the rainfall simulation box; the water supply device includes a water pipe, a water pump and a nozzle, the water pump is connected to the water pipe, one end of the water pipe is connected to the bottom of the rainfall simulation box, and the other end of the water pipe is connected to the nozzle, the nozzle is located directly above the rainfall simulation box, and the nozzle is arranged downward. Simulate the scouring effect of rainwater on the surface layer of the pavement and the soaking effect of the lower layer during the actual use of the asphalt pavement, and can adjust the water pressure and water temperature of the dynamic water scouring simulation. However, in the process of realizing the technical solution in the embodiment of the present application, the inventor of the present application found that the above technology has at least the following technical problems: the water pressure will change when water passes through the nozzle and enters the rainfall simulation box, which makes it difficult to accurately control the water pressure of the asphalt mixture specimen during the dynamic water scouring process.

[0005] The information disclosed in this background technology section is only used to deepen the understanding of the background technology of the present disclosure, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0006] The inventors discovered in scientific research practice that dynamic water scouring has an important influence on the road performance of asphalt pavement structures. In order to better simulate the effects of water environment on asphalt pavements during actual use, by introducing three factors, namely water, temperature and load, they designed and developed a test device that can truly simulate the dynamic water scouring behavior of actual asphalt pavements.

[0007] The present application provides a test device and a test method for simulating the actual dynamic water scouring behavior of asphalt pavement, organically coupling the three factors of water, temperature and vehicle load, aiming to solve the technical problem that the existing technology is difficult to truly simulate the actual dynamic water scouring behavior of asphalt pavement.

[0008] According to one aspect of the present disclosure, a test device for simulating the dynamic water scouring behavior of an actual asphalt pavement is provided, comprising a test box, a scouring unit, and a power control box, wherein the scouring unit is connected to the upper and lower parts of the test box through an upper water connection pipe and a lower water connection pipe; The test box is provided with a heating device, a sample placement plate, a metal mesh, a temperature sensor, and a movable cover plate. The heating device is provided at the bottom of the test box, the sample placement plate is provided at a distance of 20 to 30 mm from the bottom of the test box, the temperature sensor is provided at a corresponding position of the side wall of the test box, the movable cover plate is provided at the top of the test box, and the metal mesh is located below the movable cover plate; The power control box includes a power indicator light, a working indicator light, a working switch, and a temperature display; The flushing unit comprises a pressure pump, an upper water connection pipe and a lower water connection pipe, and the lower water connection pipe and the upper water connection pipe are connected to each other through the pressure pump.

[0009] In some embodiments of the present disclosure, the test box is made of Q345 steel plate.

[0010] In some embodiments of the present disclosure, the upper water connecting pipe and the lower water connecting pipe are DN32 type pipes.

[0011] In some embodiments of the present disclosure, a pressure gauge is provided at a corresponding position of the upper water pipe.

[0012] According to another aspect of the present disclosure, a test method for simulating the dynamic water scouring behavior of an actual asphalt pavement is provided, comprising the following steps: 1) Fix the asphalt mixture specimen to be tested on the specimen placement plate inside the test chamber, then fill the test chamber with water until the asphalt mixture specimen is submerged, and cover the movable cover; 2) Set the temperature range required for the test; 3) Set the required dynamic water pressure for the test to 0.15-0.25 MPa, the dynamic water flushing time to 1.5-2.5 h, and perform repeated dynamic water flushing on the asphalt mixture specimens; 4) After the simulated dynamic water scouring test of the asphalt mixture specimen is completed, the test device is turned off, the specimen is taken out, and its road performance is tested. The damage caused by the dynamic water scouring to the asphalt pavement is evaluated based on the relevant technical indicators of road performance.

[0013] In some embodiments of the present disclosure, the dynamic water flow rate is controlled to be 1 to 2 m / s.

[0014] In some embodiments of the present disclosure, the dynamic water flushing frequency is controlled to be 2s / time.

[0015] In some embodiments of the present disclosure, the dynamic water temperature is controlled to be 34-36°C.

[0016] One or more technical solutions provided in the embodiments of the present application have at least any of the following technical effects or advantages: 1. During the specific operation of the test device of the present application, the test temperature of the asphalt mixture specimen to be tested can be accurately adjusted and controlled through the heating rod, temperature sensor and temperature display inside the power control box; the dynamic water pressure of the asphalt mixture specimen to be tested can be accurately adjusted and controlled through the pressure pump and pressure gauge; the dynamic water flushing time can be accurately adjusted and controlled through the working switch inside the power control box.

[0017] 2. The test device of the present application can simulate the dynamic water scouring behavior of asphalt mixture specimens of different sizes by increasing the area of ​​the test box; through the stainless steel wire mesh provided at the lower part of the upper cover of the test box, a large-area scouring behavior of the asphalt mixture specimen to be tested can be achieved, so that the test is consistent with the dynamic water scouring state of the actual asphalt pavement, and the device structure is simple and the design is reasonable.

[0018] 3. The test device of this application realizes the coupling of factors such as water, temperature and load; at the same time, it can simulate the dynamic water scouring on the upper surface of the asphalt mixture specimen, more realistically simulate the dynamic water scouring effect caused by vehicle tires on the actual asphalt pavement surface, explore the damage caused by dynamic water scouring on the asphalt pavement, reveal the damage law of dynamic water scouring on the asphalt pavement, and provide solid theoretical support for the practical application of asphalt pavement. At the same time, the test environment simulation is close to the actual working conditions, the test results are true and accurate, and have good generalizability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the overall structure of a test device for simulating the actual dynamic water scouring behavior of an asphalt pavement in one embodiment of the present application.

[0020] Figure 2 This is a schematic diagram of the side structure of a test device for simulating the actual dynamic water scouring behavior of an asphalt pavement in one embodiment of the present application.

[0021] In the above figures: 1. test box; 2. water pump; 3. lower water pipe; 4. upper water pipe; 5. pressure gauge; 6. power control box; 7. heating rod; 8. sample placement plate; 9. movable cover; 10. asphalt mixture specimen; 11. water; 12. working indicator light; 13. power indicator light; 14. working switch; 15. temperature display; 16. stainless steel wire mesh; 17. temperature sensor. DETAILED DESCRIPTION

[0022] It should be noted that the diagrams provided in this specification are only used to illustrate the basic concept of the present application in a schematic manner, so the diagrams only show the components related to the application rather than being drawn according to the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation can be changed at will, and the layout of the components may also be more complicated. The structure, proportion, size, etc. shown in the diagrams attached to this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that the present invention can be implemented, so they have no technical substantive significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed in this application without affecting the effect and purpose that can be achieved by this application.

[0023] In order to better understand the technical solution of the present application, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. However, the following implementation methods are only used to illustrate the present invention in detail and do not limit the scope of the present invention in any way.

[0024] The present application discloses a test device for simulating the dynamic water scouring behavior of an actual asphalt pavement. Figure 1 , Figure 2 The test device for simulating the dynamic water scouring behavior of actual asphalt pavement includes a test box 1, a water pump 2, a lower water pipe 3, an upper water pipe 4, a pressure gauge 5, a power control box 6, a heating rod 7, a sample placement plate 8, a movable cover 9, a working indicator light 12, a power indicator light 13, a working switch 14, a temperature display 15, a stainless steel wire mesh 16 and a temperature sensor 17.

[0025] The test box 1 is made of Q345 steel plate, which can withstand large loads and impacts and has good corrosion resistance. A heating rod 7 is provided at the bottom of the test box 1, and the test temperature can be accurately observed at the temperature display 15 through the temperature sensor 17. A sample placement plate 8 is provided 30 mm away from the bottom of the test box 1 to fix the asphalt mixture specimen 10. A movable cover plate 9 is provided on the top of the test box 1, which can be moved back and forth for taking and placing the asphalt mixture specimen 10. A stainless steel wire mesh 16 is provided at the bottom of the movable cover plate 9 to achieve large-area flushing of the asphalt mixture specimen 10 to be tested. A lower water pipe 3 is provided on the side of the test box 1, and an upper water pipe 4 is provided on the top of the test box 1. The water pipe 3 and the upper water pipe 4 are connected by a water pump 2, so that the water inside the test box 1 can be flushed up and down, and the lower water pipe 3 and the upper water pipe 4 are both DN32 pipes, with a total length of 2m and a water flow rate of 1m / s; the upper water pipe 4 is provided with a pressure gauge 5, which can control the test water pressure, so that the water pressure in the process of dynamic water flushing can be accurately and adjustable; the power control box 6 is provided with a working indicator 12, a power indicator 13, a working switch 14 and a temperature display 15, and the working switch 14 in the power control box 6 can control the dynamic water flushing time, and the temperature display 15 can accurately monitor the test temperature, so as to achieve accurate and adjustable water and temperature in the process of dynamic water flushing. The test device simulating the dynamic water flushing behavior of the actual asphalt pavement performs dynamic water flushing on the specimen every 2s.

[0026] The specific operation process is as follows: (1) Fix the asphalt mixture specimen 10 prepared in advance on the specimen placement plate 8 inside the test box 1, then pour water 11 into the test box until the asphalt mixture specimen 10 is submerged, cover the movable cover plate 9 of the test box, and prepare for the test; (2) Set the required temperature range for the test. For example, if the required test temperature is 35°C, set the lower limit of the thermometer to 34°C and the upper limit to 36°C so that the water temperature in the device is controlled within the range of 34°C to 36°C. (3) The dynamic water pressure required for the test is set to 0.2 MPa, and the dynamic water flushing time is set to 2 h. The asphalt mixture specimen 10 is repeatedly subjected to dynamic water flushing according to the above test conditions, thereby realizing the dynamic water flushing test simulation process of the asphalt mixture specimen under the coupling effect of water, temperature and load; (4) After the simulated dynamic water scouring test of the asphalt mixture specimen 10 is completed, the test device switch is turned off, the specimen is taken out, and its road performance is tested. The damage caused by the dynamic water scouring to the asphalt pavement is evaluated based on the relevant technical indicators of road performance.

[0027] In this test, AC-20 asphalt mixture was selected. Referring to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), a 300mm×300mm×50mm rutting plate specimen was formed by the wheel rolling method for the high-temperature stability test of the asphalt mixture; the rutting plate formed by wheel rolling was cut into 250mm×30mm×35mm prismatic beams for the low-temperature crack resistance test of the asphalt mixture; the Φ101.6mm×63.5mm Marshall specimen was formed by the compaction method for the water stability test of the asphalt mixture.

[0028] By checking the rainfall in Zhengzhou over the past thirty years, it is known that the average annual rainfall in Zhengzhou is 640.9 mm, of which the rainfall in the flood seasons of May, June, July, August and September is about 491 mm. According to the survey of rainfall weather in the five months of the flood season, the average rainfall is 1 mm / h, and it can be calculated that the time for asphalt mixture to be affected by dynamic water pressure is 491 hours. A section of Zhengzhou was randomly selected for investigation, and it was found that the number of vehicles traveling in rainy weather was 156 vehicles / h, and the average driving speed was 60 km / h. Therefore, it can be obtained that the number of times the recycled aggregate asphalt pavement was affected by the dynamic water pressure generated by the vehicles was 76,596 times.

[0029] According to Bernoulli's theorem, the theoretical dynamic water pressure P can be calculated: , Where: P —Hydrodynamic pressure, Pa; —Water density, 1000kg / m 3 ; v —Vehicle speed, m / s.

[0030] Through regression analysis, the actual dynamic water pressure P on the road surface can be obtained: , Where: P — dynamic water pressure; v —Vehicle speed, km / h.

[0031] According to formula (1), the theoretical dynamic water pressure is 139.1 kPa, so the dynamic water pressure for the indoor test is designed to be 200 kPa; according to formula (2), the dynamic water pressure on the actual road surface is 11 kPa. In this example, it is assumed that the number of dynamic water pressure actions generated on the actual road surface is consistent with the number of dynamic water pressure actions generated in the indoor test. The number of dynamic water pressure actions generated in the indoor test can be calculated according to formula (3): , Where: s 1 —The number of times the hydrodynamic pressure is applied on the actual road surface; q1 —Actual road surface water dynamic pressure, kPa; s 2 —Number of times the dynamic water pressure is applied during indoor testing; q 2 —Indoor test dynamic water pressure, kPa.

[0032] According to formula (3), the number of dynamic water pressure actions generated by the indoor test is 4213 times. As the asphalt pavement is easily damaged under high temperature, the test temperature of the dynamic water action in the indoor test is designed to be the average temperature of the hottest month, 35°C.

[0033] Therefore, the indoor test conditions for dynamic water flushing are set as follows: using the dynamic water flushing simulation test device described in this application, at a temperature of 35°C and a pressure of 200 kPa, dynamic water flushing is performed 4213 times for about 2 hours.

[0034] Example 1: The test device used to simulate the dynamic water scouring behavior of actual asphalt pavement has a test method and steps that are basically the same as the above method, except that: the dynamic water scouring is performed for 0.5h under the conditions of temperature of 35°C and pressure of 0.2MPa.

[0035] Example 2: The test device used to simulate the dynamic water scouring behavior of actual asphalt pavement has a test method and steps that are basically the same as the above method, except that: dynamic water scouring is performed for 1 hour under the conditions of a temperature of 35°C and a pressure of 0.2MPa.

[0036] Example 3: The test device used to simulate the dynamic water scouring behavior of actual asphalt pavement has a test method and steps that are basically the same as the above method, except that: the dynamic water scouring is performed for 1.5 hours under the conditions of a temperature of 35°C and a pressure of 0.2MPa.

[0037] Example 4: The test device used to simulate the dynamic water scouring behavior of actual asphalt pavement has the same test method and steps as the above method, except that: the dynamic water scouring is performed for 2 hours at a temperature of 35°C and a pressure of 0.2MPa.

[0038] Example 5: The test device used to simulate the dynamic water scouring behavior of actual asphalt pavement has the same test method and steps as the above method, except that: the dynamic water scouring is carried out for 2.5 hours under the conditions of temperature of 35°C and pressure of 0.2MPa.

[0039] Example 6: The test device used to simulate the dynamic water scouring behavior of actual asphalt pavement has the same test method and steps as the above method, except that: dynamic water scouring is performed for 3 hours under the conditions of temperature of 35°C and pressure of 0.2MPa.

[0040] Example 7: The test device used to simulate the dynamic water scouring behavior of actual asphalt pavement has a test method and steps that are basically the same as the above method, except that: dynamic water scouring is performed for 3.5 hours under the conditions of a temperature of 35°C and a pressure of 0.2MPa.

[0041] Example 8: The test device used to simulate the dynamic water scouring behavior of actual asphalt pavement has a test method and steps that are basically the same as the above method, except that: dynamic water scouring is performed for 4 hours under the conditions of a temperature of 35°C and a pressure of 0.2MPa.

[0042] The AC-20 asphalt mixture in Examples 1-8 was subjected to performance tests, including a high-temperature rutting test, a low-temperature beam bending test, a freeze-thaw splitting test, and an immersion Marshall test, to test the high-temperature stability, low-temperature crack resistance, and water stability of the asphalt mixture specimens after the dynamic water scouring test of the present application. The asphalt mixture specimens that were not subjected to the dynamic water scouring test were used as a control example, and a comparative analysis of the asphalt mixture specimens under different dynamic water scouring test conditions was performed. The test results are shown in Table 1.

[0043] Table 1 Test indexes of road performance of asphalt mixture under the action of dynamic water flushing device in this application .

[0044] As can be seen from Table 1, the test results of the road performance of asphalt mixtures under the action of the dynamic water flushing device and method provided by the present application all show a trend of first rising and then falling with the extension of the dynamic water flushing time, and the various road performances of the mixture reach a peak value after 2 hours of dynamic water flushing, and begin to decline rapidly after 2 hours of dynamic water flushing. This shows that short-term dynamic water flushing has a positive effect on the road performance of the mixture, but a long dynamic water flushing time will seriously reduce the road performance of the mixture. However, the test results in the embodiments all meet the relevant technical requirements in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004).

[0045] Although some preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0046] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the inventive concept. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A test device for simulating the actual water scouring behavior of an asphalt pavement, characterized in that: It includes a test box, a flushing unit, and a power control box, wherein the flushing unit is connected to the upper and lower parts of the test box through an upper water connection pipe and a lower water connection pipe; The test box is provided with a heating device, a sample placement plate, a metal mesh, a temperature sensor, and a movable cover plate. The heating device is provided at the bottom of the test box, the sample placement plate is provided at a distance of 20 to 30 mm from the bottom of the test box, the temperature sensor is provided at a corresponding position of the side wall of the test box, the movable cover plate is provided at the top of the test box, and the metal mesh is located below the movable cover plate; The power control box includes a power indicator light, a working indicator light, a working switch, and a temperature display; The flushing unit comprises a pressure pump, an upper water connection pipe and a lower water connection pipe, and the lower water connection pipe and the upper water connection pipe are connected to each other through the pressure pump.

2. The test device for simulating the actual water scouring behavior of asphalt pavement according to claim 1 is characterized in that: The test box is made of Q345 steel plate.

3. The test device for simulating the actual water scouring behavior of asphalt pavement according to claim 1 is characterized in that: The upper water connection pipeline and the lower water connection pipeline adopt DN32 type pipes.

4. The test device for simulating the dynamic water scouring behavior of an actual asphalt pavement according to claim 1 is characterized in that: A pressure gauge is provided at a corresponding position of the upper water connection pipeline.

5. A test method for simulating the dynamic water scouring behavior of an actual asphalt pavement, characterized in that: The test device according to claim 1 is implemented, comprising the following steps: (1) Fix the asphalt mixture specimen to be tested on the specimen placement plate inside the test chamber, then fill the test chamber with water until the asphalt mixture specimen is submerged, and cover the movable cover; (2) Set the dynamic water temperature range required for the test; (3) The required dynamic water pressure for the test is set to 0.15-0.25 MPa, the dynamic water flushing time is set to 1.5-2.5 h, and the asphalt mixture specimen is repeatedly subjected to dynamic water flushing; (4) After the simulated dynamic water scouring test of the asphalt mixture specimen is completed, the test device is turned off, the specimen is taken out, and its road performance is tested. The damage caused by the dynamic water scouring to the asphalt pavement is evaluated based on the relevant technical indicators of road performance.

6. The test method according to claim 5, characterized in that The dynamic water flow rate is controlled to be 1-2 m / s.

7. The test method according to claim 5, characterized in that: In the step (3), the frequency of dynamic water flushing is controlled to be 2s / time.

8. The test method according to claim 5, characterized in that: In step (2), the moving water temperature is controlled to be 34-36°C.

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