An indoor accelerated simulation device for the self-cleaning behavior of large-void asphalt mixtures

Abstract

The present invention discloses an indoor accelerated simulation device for the self-cleaning behavior of large-void asphalt mixture, comprising an experimental box, a water discharge test bench fixed in the experimental box, and a spray mechanism fixed on both sides of the water discharge test bench, wherein the water discharge test bench is provided with a positioning mechanism; further comprising a longitudinal drive mechanism fixed on the experimental box, a rotating mechanism fixedly connected to the driving end of the longitudinal drive mechanism, and a bracket fixedly connected to the rotating shaft of the rotating mechanism, a load block is placed on the bracket, and a test wheel is connected to the end of the bracket; the test wheel is located above the water discharge test bench. The experimental device of the present invention can simulate the self-cleaning behavior of the internal voids of large-void asphalt mixture under different driving speeds, axle weights, temperatures, and ultraviolet intensity conditions, thereby providing a data basis for optimizing the proportion of large-void asphalt mixture from the perspective of extending the service life of large-void asphalt mixture, and providing guidance and suggestions for the use occasions and maintenance planning of large-void asphalt mixture.

Description

Technical Field

[0001] The invention relates to an indoor accelerated simulation device for self-cleaning behavior of large-void asphalt mixture. Background Art

[0002] With the continuous development of urban road construction, the concept of sponge city is gradually entering the vision of planning and design personnel. For example, Nanjing City issued the "Sponge City Planning and Construction Management Regulations" in 2019, focusing on promoting the construction of sponge pilot projects in Jiangxinzhou Ecological Science and Technology Island and Dingjiazhuang Affordable Housing Area. Large-void asphalt mixture can not only meet the requirements of conventional asphalt pavement to resist repeated driving loads, but also provide good drainage and noise reduction performance. Using large-void asphalt mixture as the surface layer to form a drainage pavement can achieve timely lateral discharge of rainwater along the internal voids of the surface layer during rainfall, effectively reducing the formation of water film on the road surface, reducing the possibility of vehicle slippage, and reducing the water mist on the side and rear of the tire, providing better visibility for the rear driver and significantly improving driving safety. At the same time, the large-void structure has a good noise reduction effect. When the tire contacts the road surface to produce the "air pump suction" effect, the compressed air can quickly diffuse into the road surface through the connected voids, and some energy can be consumed during the diffusion process, that is, the noise intensity is reduced from the source. Studies have shown that large-void asphalt pavements generally reduce the accident rate on rainy days by 76% compared with ordinary asphalt pavements, and reduce noise by 3-8 decibels.

[0003] Asphalt mixture with large voids will inevitably become the development trend of asphalt pavement in the future, and its drainage and noise reduction performance is closely related to its void ratio. As the pavement is used for a longer time, solid materials such as particulate matter in the air, tire wear materials, and other turbid materials in rainwater gather in the voids of the asphalt mixture under the action of gravity or rainwater, resulting in a decrease in the actual void ratio of the asphalt mixture, and thus the drainage and noise reduction performance of the pavement will be greatly reduced or even disappear. Therefore, the recovery of the void ratio of asphalt mixture with large voids is extremely important.

[0004] Relevant research shows that the "air pumping" effect generated by the contact between vehicle tires and the road surface can cause pollutants accumulated in the road surface voids to loosen or even rush out of the internal voids under severe vibration, achieving the effect of gradually restoring the actual porosity of the road surface, thereby gradually restoring the drainage and noise reduction performance. This is the "self-cleaning behavior" of the internal voids of large-void asphalt mixtures. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide an experimental device that can simulate the self-cleaning behavior of the internal voids of large-void asphalt mixtures under different driving speeds, axle loads, temperatures, ultraviolet intensities and different pollutant concentrations.

[0006] Technical solution: The indoor accelerated simulation device for the self-cleaning behavior of large-void asphalt mixture described in the present invention includes an experimental box, a water discharge test bench fixed in the experimental box, and a spray mechanism fixed on both sides of the water discharge test bench, wherein the water discharge test bench is provided with a positioning mechanism; it also includes a longitudinal drive mechanism fixed on the experimental box, a rotating mechanism fixedly connected to the driving end of the longitudinal drive mechanism, and a bracket fixedly connected to the rotating shaft of the rotating mechanism, a load block is placed on the bracket, and a test wheel is connected to the end of the bracket; the test wheel is located above the water discharge test bench.

[0007] Wherein, the experimental box is also provided with an ultraviolet lamp and a heating device.

[0008] Among them, the asphalt mixture specimen is placed on a water leakage test bench, the upper surface area of ​​the water leakage test bench is larger than the bottom area of ​​the asphalt mixture specimen, and a plurality of through-hole structures are provided on the upper surface of the water leakage test bench, which are communicated with the inner cavity of the water leakage test bench, and the inner cavity of the water leakage test bench is connected to the drainage water tank through a pipe.

[0009] The spray mechanism includes a riser fixed on the side of the water discharge test bench and a spray head fixed on the water outlet end of the riser. The water inlet end of the riser is connected to the water supply tank through a pipeline, and a lifting pump is provided on the pipeline.

[0010] The angle between the spray head and the horizontal plane is adjustable; the spray direction of the spray head faces the water discharge test bench.

[0011] Among them, the positioning mechanism includes a fixed plate fixed on the water discharge test bench, a movable plate arranged opposite to the fixed plate, and a hydraulic cylinder driving the movable plate to move along the water discharge test bench towards or away from the fixed plate; the fixed end of the hydraulic cylinder is fixed in the test box, and the driving end of the hydraulic cylinder is fixedly connected to the movable plate.

[0012] Among them, the longitudinal driving mechanism is a cylinder, the rotating mechanism is a motor, the cylinder is fixed to the top of the experimental box through a connecting frame, the fixed end of the cylinder is fixed on the connecting frame, and the driving end of the cylinder passes through the connecting frame and is fixedly connected to the motor.

[0013] Wherein, a coupling is provided at the connection between the motor rotating shaft and the bracket.

[0014] Beneficial effects: The experimental device of the present invention can simulate the self-cleaning behavior of the internal voids of the large-void asphalt mixture under different driving speeds, axle weights, temperatures and ultraviolet intensity conditions, so as to provide a data basis for optimizing the proportion of the large-void asphalt mixture from the perspective of extending the service life of the large-void asphalt mixture, and provide guidance and suggestions for the use occasions and maintenance planning of the large-void asphalt mixture, thereby effectively improving the use effect of the large-void asphalt mixture. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the structural principle diagram of the experimental device of the present invention. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0017] like Figure 1 As shown in the figure, the indoor accelerated simulation device for the self-cleaning behavior of large-void asphalt mixture of the present invention comprises an experimental box 2 with a horizontal sliding door 7, a water discharge test bench 17 fixed in the experimental box 2, and a spray mechanism fixed on both sides of the water discharge test bench 17, the spray mechanism comprises a riser 15 fixed on the side of the water discharge test bench 17 and a spray head 9 fixed on the water outlet end of the riser 15, the water inlet end of the riser 15 is connected to the water supply tank 19 through a pipe 26, and a lifting pump is provided on the pipe 26; the spray head 9 is arranged at an angle greater than 0° with the horizontal plane, and the spray direction of the spray head 9 faces the water discharge test bench 17; The green mixture specimen 14 is placed on the water discharge test bench 17. The upper surface area of ​​the water discharge test bench 17 is larger than the bottom surface area of ​​the asphalt mixture specimen 14. The upper surface of the water discharge test bench 17 is provided with a plurality of through-hole structures, which are communicated with the inner cavity of the water discharge test bench. The inner cavity of the water discharge test bench is connected to the drainage water tank 1 outside the box body 2 through a drainage pipe 18. The water discharge test bench 17 is provided with a positioning mechanism, which includes a fixed plate 16 fixed on the water discharge test bench 17, a movable plate 11 arranged opposite to the fixed plate 16, and a driving plate 11 to move along the water discharge test bench 17 close to the fixed plate 16. The hydraulic cylinder 10 is a hydraulic cylinder 10 that moves away from the fixed plate 16, the fixed end of the hydraulic cylinder 10 is fixed on the bottom plate of the experimental box 2, the driving end of the hydraulic cylinder 10 is fixedly connected to the moving plate 11, and the distance between the moving plate 11 and the fixed plate 16 is adjusted according to the size of the asphalt mixture specimen 14 placed on the water discharge test bench 17; the indoor acceleration simulation device for the self-cleaning behavior of large-void asphalt mixture of the present invention also includes a longitudinal driving mechanism fixed on the experimental box 2, a rotating mechanism fixedly connected to the driving end of the longitudinal driving mechanism, and a bracket 23 fixedly connected to the rotating shaft of the rotating mechanism, and the bracket 23 includes A connecting rod 24 and a U-shaped frame 25 fixedly connected to the connecting rod 24, a load block 8 is placed on the horizontal beam of the U-shaped frame 25, and test wheels 13 are connected to both ends of the U-shaped frame 25; the test wheel 13 is located directly above the water discharge test bench 17; the longitudinal driving mechanism is a cylinder 21, and the rotating mechanism is a motor 3. The cylinder 21 is fixed to the top of the test box 2 through a connecting frame 20, and the fixed end of the cylinder 21 is fixed to the connecting frame 20. The driving end 22 of the cylinder 21 passes through the connecting frame 20 and is fixedly connected to the motor 3. A coupling 6 is provided at the connection between the rotating shaft of the motor 3 and the connecting rod 24 of the bracket 23.

[0018] An ultraviolet lamp 5 and a heating device 4 are also provided in the experimental box 2 ; the heating device 4 is a PTC air heater, and the ultraviolet lamp 5 is symmetrically arranged on the top plate of the experimental box 2 .

[0019] The device of the present invention is used for indoor accelerated simulation test of self-cleaning behavior of large-void asphalt mixture, and evaluates the self-cleaning behavior ability of large-void asphalt mixture under corresponding driving speed, axle load, temperature and ultraviolet intensity;

[0020] The specific test steps are as follows:

[0021] (1) Asphalt mixture specimen 14 was formed according to the test specification, and the initial water permeability coefficient of the asphalt mixture specimen was measured according to the "Test Specification for Asphalt and Asphalt Mixture for Highway Engineering" (JTG E20), which was recorded as C1;

[0022] (2) Determine the composition of simulated sewage, mix particulate matter and turbid matter into a pollutant solution of a certain concentration according to a certain proportion, and add the pollutant solution into the water supply tank 19, which serves to provide gap plugging;

[0023] (3) Open the sliding door 7 of the test box 2, lift the test wheel 13 through the longitudinal drive mechanism, place the test piece 14 on the water discharge test bench 17, and adjust the distance between the movable plate 11 and the fixed plate 16 through the hydraulic cylinder 10 so that the test piece 14 is fixed between the movable plate 11 and the fixed plate 16;

[0024] (4) Close the sliding door 7, turn on the lifting pump on the pipe 26 between the water supply tank 19 and the riser 15, and adjust the flow rate to the test requirement. After the water flow from the sprinkler head 9 is stable, start the timing. During the test, pay attention to the remaining amount of sewage in the water supply tank 19, and timely configure and replenish the sewage with the specified concentration;

[0025] (5) During the test, water that passes through the asphalt mixture specimen 14 will flow into the inner cavity of the water discharge test bench through the through hole on the water discharge test bench 17, and then be discharged to the drainage water tank 1 through the drainage pipe 18;

[0026] (6) After the required test time is reached, the lifting pump is turned off, the horizontal sliding door 7 is opened, the test piece 14 is taken out, and the water permeability coefficient of the asphalt mixture test piece 14 after the gap is blocked is measured, which is recorded as C2;

[0027] (7) Repeat the above step 3, place the asphalt mixture specimen 14 back on the test bench 17, lower the test wheel 13 through the longitudinal drive mechanism, adjust the number of load blocks 8 on the horizontal beam of the U-shaped frame 25 until the test pressure is required, push the horizontal sliding door latch 12 to close the horizontal sliding door 7, and avoid temperature loss in the box 2 during the test;

[0028] (8) Turn on the PTC air heater 4 on the side wall of the test box 2 and adjust it to the temperature required by the test; at the same time, turn on the ultraviolet lamp 5 and adjust it to the ultraviolet intensity required by the test;

[0029] (9) Turn on the motor 3, adjust the speed of the test wheel 13 to the required test speed, make it move in a uniform circular motion on the asphalt mixture specimen 14, perform a pumping action on it, and start timing;

[0030] (10) After the required test time is reached, turn off the PTC air heater 4, the UV lamp 5 and the motor 3, open the sliding door 7, lift the test wheel 13, take out the test specimen 14, and measure the water permeability coefficient of the asphalt mixture specimen 14 after the gap is self-cleaned under the action of the tire pump suction, which is recorded as C3, and calculate the recovery coefficient of the water permeability coefficient of the specimen according to the following formula: R = (C3-C2) / C1×100%. The larger the value, the stronger the self-cleaning behavior ability of the asphalt mixture under the corresponding driving speed, axle weight, temperature, and ultraviolet intensity; in the formula, C1 is the initial water permeability coefficient of the specimen; C2 is the water permeability coefficient of the specimen after being blocked by pollutants; C3 is the water permeability coefficient of the specimen after self-cleaning; R is the coefficient of the self-cleaning behavior ability of the specimen.

[0031] The device of the present invention can also be used for accelerated wear test of asphalt mixture specimens to evaluate the wear resistance of asphalt mixture under corresponding driving speed, axle load, temperature and ultraviolet intensity;

[0032] The specific test steps are as follows:

[0033] (1) Asphalt mixture specimen 14 was molded according to the test specification, and the initial anti-skid coefficient of the asphalt mixture specimen was measured according to the "Test Specification for Asphalt and Asphalt Mixture for Highway Engineering" (JTG E20), which was recorded as S1;

[0034] (2) Open the sliding door 7 of the test box 2, lift the test wheel 13 through the longitudinal drive mechanism, place the test piece 14 on the water discharge test bench 17, and adjust the distance between the movable plate 11 and the fixed plate 16 through the hydraulic cylinder 10 so that the test piece 14 is fixed between the movable plate 11 and the fixed plate 16;

[0035] (3) Lower the test wheel 13 through the longitudinal drive mechanism, adjust the number of load blocks 8 on the horizontal beam of the U-shaped frame 25 until the test pressure is required, push the horizontal sliding door latch 12 to close the horizontal sliding door 7, avoid the temperature loss in the box 2 during the test, and close the horizontal sliding door 7;

[0036] (4) Turn on the PTC air heater 4 on the side wall of the test box 2 and adjust it to the temperature required by the test; at the same time, turn on the ultraviolet lamp 5 and adjust it to the ultraviolet intensity required by the test;

[0037] (5) Turn on the motor 3, adjust the speed of the test wheel 13 to the required test speed, make it make uniform circular motion on the asphalt mixture specimen 14, wear it, and start timing;

[0038] (6) After the required test time is reached, turn off the PTC air heater 4, the UV lamp 5 and the motor 3, open the sliding door 7, take out the test piece 14, measure the anti-skid coefficient of the asphalt mixture test piece 14 after wear, record it as S2, and calculate the anti-skid performance attenuation coefficient of the test piece according to the following formula: T = (C2-C1) / C1×100%. The larger the value (T), the higher the degree of anti-skid performance attenuation of the asphalt mixture under the corresponding driving speed, axle load, temperature, and UV intensity; in the formula, S1 is the initial anti-skid coefficient of the test piece; C2 is the anti-skid coefficient of the test piece after wear; T is the anti-skid performance attenuation coefficient of the test piece.

Claims

1. An indoor accelerated simulation device for self-cleaning behavior of large-void asphalt mixture, characterized in that: It includes an experimental box, a water discharge test bench fixed in the experimental box, and a spray mechanism fixed on both sides of the water discharge test bench, and a positioning mechanism is provided on the water discharge test bench; it also includes a longitudinal drive mechanism fixed on the experimental box, a rotating mechanism fixedly connected to the driving end of the longitudinal drive mechanism, and a bracket fixedly connected to the rotating shaft of the rotating mechanism, a load block is placed on the bracket, and a test wheel is connected to the end of the bracket; the test wheel is located above the water discharge test bench; an ultraviolet lamp and a heating device are also provided in the experimental box; the inner cavity of the water discharge test bench is connected to the drainage water tank through a pipeline; the spray mechanism includes risers fixed on both sides of the water discharge test bench and a spray head fixed at the water outlet end of the riser, and the water inlet end of the riser is connected to the water supply tank through a pipeline; the positioning mechanism includes a fixed plate fixed on the water discharge test bench, a movable plate arranged opposite to the fixed plate, and a hydraulic cylinder driving the movable plate to move along the water discharge test bench to move closer to or away from the fixed plate; The above device is used for indoor accelerated simulation test of self-cleaning behavior of large-void asphalt mixture. The specific test steps are as follows: (1) Asphalt mixture specimens are formed according to the test procedures, and the initial water permeability coefficient of the asphalt mixture specimens is measured according to JTG E20 "Test Procedures for Asphalt and Asphalt Mixtures for Highway Engineering", which is recorded as C1; (2) Determine the composition of simulated sewage, mix particulate matter and turbidity into a pollutant solution of a certain concentration in proportion, and add the pollutant solution into the water supply tank to provide gap plugging; (3) Open the sliding door of the test box, lift the test wheel through the longitudinal drive mechanism, place the test specimen on the water discharge test bench, and adjust the distance between the movable plate and the fixed plate through the hydraulic cylinder so that the test specimen is fixed between the movable plate and the fixed plate; (4) Close the sliding door, turn on the lifting pump on the pipe between the water supply tank and the riser, and adjust it to the required flow rate. When the water flow from the sprinkler head is stable, start the timing. During the test, pay attention to the remaining amount of sewage in the water supply tank, and timely configure and replenish the sewage with the specified concentration; (5) During the test, water that passes through the asphalt mixture specimen will flow into the inner cavity of the water discharge test bench through the through holes on the water discharge test bench, and then be discharged to the drainage water tank through the drainage pipe; (6) After the required test time is reached, turn off the lifting pump, open the sliding door, take out the specimen, and measure the water permeability coefficient of the asphalt mixture specimen after the gap is blocked, which is recorded as C2; (7) Repeat the above step (3), place the asphalt mixture specimen back on the test bench, lower the test wheel through the longitudinal drive mechanism, adjust the number of load blocks on the bracket until the test pressure is met, and push the sliding door latch to close the sliding door to prevent the temperature inside the box from dissipating during the test; (8) Turn on the PTC air heater on the side wall of the test chamber and adjust it to the temperature required by the test; at the same time, turn on the UV lamp and adjust it to the UV intensity required by the test; (9) Turn on the motor and adjust the test wheel speed to the required test speed, so that it makes uniform circular motion on the asphalt mixture specimen, performs pumping action on it, and starts timing; (10) After the required test time is reached, turn off the PTC air heater, UV lamp and motor, open the sliding door, lift the test wheel, take out the test specimen, and measure the water permeability coefficient of the asphalt mixture specimen after self-cleaning of the gap under the action of tire pump suction, denoted as C3, and calculate the specimen water permeability recovery coefficient according to the following formula: R = (C3-C2) / C1×100%; where C1 is the initial water permeability coefficient of the specimen; C2 is the water permeability coefficient of the specimen after being blocked by pollutants; C3 is the water permeability coefficient of the specimen after self-cleaning; R is the self-cleaning behavior coefficient of the specimen; the R value is used to evaluate the self-cleaning behavior ability of the asphalt mixture under the corresponding driving speed, axle load, temperature and ultraviolet intensity.

2. The indoor accelerated simulation device for self-cleaning behavior of large-void asphalt mixture according to claim 1 is characterized in that: The asphalt mixture specimen is placed on a water leakage test bench, the upper surface area of ​​the water leakage test bench is larger than the bottom surface area of ​​the asphalt mixture specimen, and a plurality of through hole structures are arranged on the upper surface of the water leakage test bench, which are communicated with the inner cavity of the water leakage test bench.

3. The indoor accelerated simulation device for self-cleaning behavior of large-void asphalt mixture according to claim 1, characterized in that: A lifting pump is arranged on the pipeline.

4. The indoor accelerated simulation device for self-cleaning behavior of large-void asphalt mixture according to claim 1, characterized in that: The fixed end of the hydraulic cylinder is fixed in the experimental box, and the driving end of the hydraulic cylinder is fixedly connected to the movable plate.

5. The indoor accelerated simulation device for self-cleaning behavior of large-void asphalt mixture according to claim 1, characterized in that: The longitudinal driving mechanism is a cylinder, and the rotating mechanism is a motor. The cylinder is fixed to the top of the experimental box through a connecting frame, the fixed end of the cylinder is fixed to the connecting frame, and the driving end of the cylinder passes through the connecting frame and is fixedly connected to the motor.

6. The indoor accelerated simulation device for self-cleaning behavior of large-void asphalt mixture according to claim 1, characterized in that: A coupling is provided at the connection between the motor rotating shaft and the bracket.

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