Aggregate adhesion test device and test method based on pressure vessel

Abstract

The present invention discloses an aggregate adhesion test device and test method based on a pressure vessel. It includes a pressure vessel that can be sealed, an instrument housing with a control system, and a heating device for heating the pressure vessel. The asphalt-coated aggregate to be tested can be placed in the pressure vessel. An air pressure compensation device is arranged on the side of the pressure vessel. The air pressure compensation device is connected to the pressure vessel and can compensate the pressure in the pressure vessel through the control of the control system so that the heating temperature of the water is not limited by the atmospheric pressure of the test environment, and then the water temperature required for the adhesion test between the aggregate and the asphalt is determined according to the softening point of different asphalts. The advantages are: it can meet the requirements of the determination of the adhesion between the aggregate and the traditional road petroleum asphalt, and also meet the requirements of the adhesion between the aggregate and the special asphalt such as polymer modified asphalt, rubber asphalt, composite modified asphalt, etc., and at the same time is not subject to the limitation of the atmospheric pressure of the test environment.

Description

Technical Field

[0001] The invention relates to an aggregate-asphalt adhesion test device based on the saturated vapor pressure of water, in particular to an aggregate adhesion test device and a test method based on a pressure vessel, belonging to the technical field of road engineering. Background Art

[0002] In recent years, with the continuous development of my country's transportation industry, the total mileage of highways has continued to increase, and the quality level has continued to improve. However, the early damage of highway pavement, especially the early water damage such as loosening, peeling and potholes of asphalt pavement under the repeated effects of temperature, rain, traffic load and other factors, not only reduces the service life of asphalt pavement, but also makes the highway enter a large-scale maintenance period ahead of time, increasing the maintenance cost of the road surface, which has gradually attracted widespread attention in the highway industry.

[0003] The main cause of water damage to asphalt pavement is that water penetrates between the aggregate and the asphalt film of the asphalt mixture, causing two destructive effects: reducing the adhesion of asphalt to mineral materials; destroying the bonding between asphalt mixtures. Therefore, evaluating the adhesion between aggregate and asphalt through real and effective methods and taking corresponding technical means to improve the ability of the asphalt film on the aggregate surface to resist peeling caused by water erosion is an important way to increase the service life of asphalt pavement.

[0004] At present, the water boiling method is the standard method for evaluating the adhesion between coarse aggregate and asphalt in the current regulations. Its basic steps are as follows: ① Take 5 aggregates of 13.2-19 mm, clean them with water, tie them with thin wires, and heat them in an oven at 105℃±5℃ for 1h; ② Lift the heated aggregate particles one by one, immerse them in pre-heated asphalt (130℃-150℃) for 45s, and then gently take them out so that the surface of the aggregate is completely and evenly covered with the asphalt film, and then hang the aggregates covered with the asphalt film on the sample rack to cool for 15min; ③ After the aggregate particles are cooled, lift them one by one with wires and immerse them in the center of a large beaker filled with slightly boiling water. Adjust the heating furnace to keep the water in the beaker in a slightly boiling state, but no boiling foam is allowed; ④ After immersion and boiling for 3min, take the aggregate out of the water, cool it appropriately, and then put it into a beaker filled with water at room temperature. Visually observe the degree of peeling of the asphalt film on the surface of the aggregate particles, and judge the adhesion between the aggregate and asphalt according to the degree of peeling.

[0005] Through theoretical analysis, combined with the description of the adhesion between aggregate and asphalt determined by the boiling method, it can be known that the key factors affecting the adhesion between aggregate and asphalt determined by the boiling method are: ① The acidity and alkalinity of the aggregate surface. Due to the presence of asphalt anhydride, asphalt is acidic. Therefore, the stronger the alkalinity of the aggregate surface, the better the adhesion with asphalt, and vice versa. The adhesion with asphalt is worse; ② The microscopic roughness of the aggregate surface. The larger the microscopic pores on the aggregate surface, the greater the mutual sliding resistance with asphalt, and the better the adhesion. On the contrary, the smoother the aggregate surface, the worse the adhesion; ③ The viscosity of asphalt. The greater the viscosity of asphalt, the greater the adhesion between asphalt and the aggregate surface. The greater the attachment work and adhesion, the stronger the ability to resist water peeling and the better the adhesion; ④ The cohesive force between asphalt molecules. The greater the cohesive force between asphalt molecules, the stronger the ability of the asphalt film to resist water tearing, and water is not easy to penetrate into the bonding surface between asphalt and aggregate; ⑤ The water temperature and bubble size in the slightly boiling state. Since asphalt is a temperature-sensitive material, the higher the temperature, the lower the asphalt viscosity. At the same time, the larger the bubbles, the greater the scouring kinetic energy of the water. Therefore, the higher the water temperature and the larger the bubbles during slight boiling, the easier it is for the asphalt to fall off from the aggregate surface; ⑥ The length of the slight boiling time. The longer the slight boiling time, the more obvious the erosion effect of water. Looking at the above key factors that affect the water boiling method for determining the adhesion between aggregate and asphalt, under the premise of determined materials, the acidity and roughness of the aggregate surface, the viscosity of asphalt and the cohesion between asphalt molecules are fixed, so the factors that can affect the authenticity of the water boiling method are the water temperature during slight boiling, the foam size and the slight boiling time. Among them, the test procedures for the foam size during slight boiling and the slight boiling time are strictly limited and can only be followed. Therefore, the determination of the slight boiling state and the water temperature are the core of the authenticity of the reaction water boiling method for determining the adhesion between aggregate and asphalt.

[0006] However, the reason why the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" stipulates that the micro-boiling temperature for determining the adhesion between coarse aggregate and asphalt by the water boiling method is 100°C is based on two reasons: a large number of studies have shown that testing at 50°C above the asphalt softening point can better simulate the water erosion process under the conditions of asphalt pavement use; due to historical limitations, the asphalt used in my country's asphalt pavements at the time was ordinary road petroleum asphalt, which has a softening point of about 50°C. However, with the continuous development of asphalt material technology, in addition to road petroleum asphalt, a large number of high-viscosity and high-cohesion polymer modified asphalt, rubber asphalt, composite modified asphalt and other special asphalts are used in asphalt pavement construction and maintenance projects. Their softening points are much higher than 50℃, basically around 80℃, and even more so above 90℃. If 100℃ is still used as the micro-boiling temperature, the hard core asphalt film formed by the special asphalt on the aggregate surface is not enough to be softened, blocking the infiltration of water, and the measured adhesion results are always good. The appearance of the test results causes the distortion of the adhesion between aggregate and asphalt, thus laying a major hidden danger for water damage to asphalt pavement. At the same time, the micro-boiling state of water is subject to atmospheric pressure. Under standard atmospheric pressure, 100℃ is the critical temperature of water in liquid and gaseous states. As the atmospheric pressure decreases, the critical temperature also decreases. Therefore, the adhesion between aggregate and asphalt measured by the standard water boiling method in high altitude areas is higher than the true adhesion, while the measured value in low altitude areas is lower than the true adhesion.

[0007] In this context, it is necessary to develop a test device for measuring the adhesion between aggregate and asphalt, which is not only suitable for measuring the adhesion between aggregate and traditional road petroleum asphalt, but can also accurately determine the adhesion between aggregate and special asphalt, and is not restricted by the atmospheric pressure of the measurement environment, providing a new way to study and evaluate the adhesion between asphalt and coarse aggregate. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide an aggregate adhesion test device and test method based on a pressure vessel that can meet the requirements of the adhesion test between aggregate and traditional road petroleum asphalt, as well as the adhesion test between aggregate and special asphalts such as polymer modified asphalt, rubber asphalt, composite modified asphalt, etc., and is not restricted by the limitation of the atmospheric pressure of the measuring environment.

[0009] In order to solve the above technical problems, the aggregate adhesion testing device based on a pressure vessel of the present invention includes a sealable pressure vessel, an instrument housing with a control system and a heating device for heating the pressure vessel. The asphalt-coated aggregate to be tested can be placed in the pressure vessel. An air pressure compensation device is provided on the side of the pressure vessel. The air pressure compensation device is connected to the pressure vessel and can compensate for the pressure in the pressure vessel through the control of the control system so that the heating temperature of the water is not limited by the atmospheric pressure of the test environment, and then the water temperature required for the adhesion test between the aggregate and the asphalt is determined according to the softening points of different asphalts.

[0010] A stirring device is arranged in the pressure container.

[0011] The stirring device is a magnetic stirrer.

[0012] The heating device is an electromagnetic heating plate arranged at the bottom of the pressure container.

[0013] The air pressure compensation device comprises an air booster pump located beside the pressure container and a pressure air pipeline connected to the air booster pump, wherein the pressure air pipeline extends into the pressure container.

[0014] A pressure vessel cover is arranged on the top of the pressure vessel, and a secondary safety valve and a primary safety valve are arranged on the pressure vessel cover.

[0015] A pressure sensor and a temperature sensor are arranged in the pressure container.

[0016] The control system comprises a time controller, a temperature controller, a pressure controller and a stirring device adjustment knob.

[0017] A sample rack is arranged in the pressure container, and the asphalt-coated aggregate is suspended on the sample rack by a wire rope.

[0018] Two tie rods are arranged on the sides of the pressure vessel, a pressure strip located at the top of the pressure vessel is arranged between the tops of the two tie rods, and a pressure strip limiter is arranged on the pressure strip.

[0019] The pressure container is provided with a test observation window.

[0020] A method for testing the adhesion of aggregates based on a pressure vessel, characterized in that it comprises the following steps:

[0021] (1) Screen the aggregate to be tested, take 5 aggregates with a size of 13.2-19 mm, clean them with water, tie them tightly with a string, and heat them in an oven at 105℃±5℃;

[0022] (2) According to the asphalt softening point test method in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", test the softening point of the asphalt used in the test;

[0023] (3) Lift the heated aggregate particles one by one, immerse them in pre-heated asphalt (softening point +80°C) for 40-50 seconds, and then take them out so that the aggregate surface is completely and evenly coated with the asphalt film. Then hang the aggregate coated with the asphalt film on the sample rack to cool for 10-20 minutes;

[0024] (4) Determine the test water temperature based on the softening point of the asphalt used in the test. The test water temperature is the softening point of the asphalt + 50°C.

[0025] (5) According to the test water temperature, look up the table to obtain the saturated vapor pressure of water at that temperature;

[0026] (6) According to the saturated vapor pressure of water, set the value of the pressure controller so that the pressure in the pressure vessel during the test is constant at the saturated vapor pressure of water + 20Kpa;

[0027] (7) Set the value of the temperature controller to the test water temperature;

[0028] (8) Set the value of the time controller;

[0029] (9) Add water heated to 85-95°C into the pressure vessel. The amount of water added should be 3-5 cm higher than the temperature sensor;

[0030] (10) After the aggregate particles have cooled, they are lifted one by one with a wire and placed on a sample rack. They are then immersed in water at 85-95°C and added to a pressure vessel. The main power switch, air booster pump power switch, and heating power switch are then turned on in sequence. The stirring device is adjusted to keep the water in a micro-motion state. The heating temperature is fine-tuned by the bubbles that form when the water boils during the test.

[0031] (11) After the immersion time is over, open the primary and secondary safety valves to reduce the air pressure in the pressure vessel to atmospheric pressure. Then take the aggregate out of the water, cool it, and put it into a beaker filled with water at room temperature. Visually inspect the degree of peeling of the asphalt film on the surface of the aggregate particles. Judge the adhesion between the aggregate and the asphalt based on the degree of peeling.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. Compared with the traditional test, the air pressure compensation device is arranged on the side of the pressure vessel so that the heating temperature of the water is not limited by the atmospheric pressure of the test environment. Then, the water temperature required for the adhesion test between aggregate and asphalt can be conveniently determined according to the softening points of different asphalts. Under this water temperature condition, the water is in a slightly boiling state, which not only meets the requirements of the adhesion test between aggregate and traditional road petroleum asphalt, but also meets the requirements of the adhesion test between aggregate and special asphalt such as polymer modified asphalt, rubber asphalt, and composite modified asphalt. At the same time, it is not restricted by the limitation of the atmospheric pressure of the test environment, which completely solves the defects of the water boiling method for determining the adhesion between coarse aggregate and asphalt in the existing "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering".

[0034] 2. The magnetic stirrer and electromagnetic heating plate can ensure that the water temperature is more uniform. During the test, the water can be kept in a slightly boiling state without producing boiling foam. The test results are more accurate. At the same time, the control unit is set to make it simple and fast to operate, and the data is scientific and accurate.

[0035] 3. The primary and secondary safety valves are set to limit the maximum pressure of the air booster pump, and the minimum allowable pressure of the pressure vessel and the observation window, which can greatly improve the safety factor of the equipment and make the test process safe and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of an aggregate adhesion test device based on a pressure vessel of the present invention;

[0037] In the figure: 1. Pressure vessel cover; 2. Secondary safety valve; 3. Pressure strip limiter; 4. Primary safety valve; 5. Pressure strip; 6. Sealing rubber ring; 7. Pull rod; 8. Pressure vessel; 9. Pressure air pipeline; 10. Asphalt-coated aggregate; 11. Pressure sensor; 12. Thin wire; 13. U-shaped support block; 14. Test observation window; 15. Limiter; 16. Temperature sensor; 17. Test water; 18. Bolt; 19. Air booster pump; 20. Magnetic stirrer; 21. Air booster pump power switch; 22. Heating power switch; 23. Main power switch; 24. Sample rack; 25. Magnetic stirrer adjustment knob; 26. Pressure controller; 27. Temperature controller; 28. Time controller; 29. ​​Controller signal light; 30. Support seat; 31. Instrument housing; 32. Electromagnetic heating plate. DETAILED DESCRIPTION

[0038] The following is a further detailed description of the aggregate adhesion test device and test method based on a pressure vessel of the present invention in conjunction with the accompanying drawings and specific embodiments. Example

[0039] As shown in the figure, the aggregate adhesion test device based on the pressure vessel of the present invention can be used to accurately measure the adhesion between various types of road aggregates, blocks and different types of asphalt materials such as basalt, limestone, diabase, granite, etc. under different altitude conditions. It includes a closed pressure vessel 8, an instrument housing 31 with a control system, and a heating device for heating the pressure vessel 8. The pressure vessel selected in this embodiment is a cylindrical structure, and the bottom and the wall of the pressure vessel are welded, and the maximum allowable pressure is greater than 1.5Mpa; as can be seen from the figure, the heating device is an electromagnetic heating disk 32 arranged at the bottom of the pressure vessel 8. The electromagnetic heating disk selected in this embodiment can raise 3L of water at 90°C to 150°C within 30s; a pressure vessel cover 1 is arranged on the top of the pressure vessel 8, and the pressure vessel cover 1 and the pressure vessel 8 can be threadedly connected. A sealing ring 6 is arranged between the pressure vessel cover 1 and the pressure vessel 8, thereby the pressure vessel 8 can be closed, and a stirring device 20 is arranged in the pressure vessel 8, and the stirring device 20 is preferably a magnetic In this embodiment, two magnetic stirrers are provided at the bottom of the pressure vessel, and a sample rack 24 is provided in the pressure vessel 8. Specifically, two U-shaped support blocks 13 arranged opposite to each other are installed on the inner wall of the pressure vessel 8. When installed, the U-shaped support blocks are welded and fixed to the cylinder wall of the pressure vessel. The sample rack is fixed by the two U-shaped support blocks; the sample rack 24 is horizontally installed between the two U-shaped support blocks 13, and the sample rack 24 has an aggregate 10 wrapped with asphalt hoisted by a wire rope (thin rope) 12, and the pressure vessel 8 contains test water 17. The asphalt-coated aggregate 10 is immersed in the test water 17. A test observation window 14 is arranged on the front of the cylinder wall of the pressure vessel. A pressure sensor 11 and a temperature sensor 16 are also arranged in the pressure vessel 8. An air pressure compensation device is arranged on the side of the pressure vessel 8. The air pressure compensation device is connected to the pressure vessel 8 and can compensate the pressure in the pressure vessel through the control of the control system so that the heating temperature of the water is not limited by the atmospheric pressure of the test environment, and then the water temperature required for the adhesion test between the aggregate and the asphalt is determined according to the softening point of different asphalts.

[0040] In addition, during installation, in order to save space and facilitate operation, the pressure vessel 8 is installed on the upper part of the instrument housing 31, that is, the electromagnetic heating disk is located on the top surface of the instrument housing, and the pressure vessel is directly above the electromagnetic heating disk. At the same time, in order to ensure the reliability of the installation position of the pressure vessel 8, four limit blocks 15 are arranged on the instrument housing 31 and are located on the periphery of the pressure vessel 8. Four support seats 30 are arranged at the bottom of the instrument housing 31. The four support seats 30 are made of high-strength rubber material, are fixedly connected to the instrument housing, and are supported at the four corners of the instrument housing; the instrument housing 31 is also provided with a main power switch 23, an air booster pump power switch 21 and a heating power switch 22; of course, a time controller 28, a temperature controller 27, a pressure controller 26 and a magnetic A magnetic stirrer adjustment knob (stirring device adjustment knob) 25 and multiple controller signal lights 29, wherein the time controller is linked to the heating power switch and the air booster pump power switch signal, the pressure controller is linked to the air booster pump power switch signal, the temperature controller is linked to the heating power switch signal, and the pressure controller is linked to the temperature controller signal; as can be seen from the figure, a controller signal light 29 for indicating control information is also provided above the time controller 28, the temperature controller 27, and the pressure controller 26, respectively. The control system uses the time controller 28, the temperature controller 27, the pressure controller 26 and the magnetic stirrer adjustment knob 25 as a control unit, and the operation of the magnetic stirrer can be controlled by adjusting the magnetic stirrer adjustment knob 25.

[0041] Furthermore, the air pressure compensation device includes an air booster pump 19 located next to the pressure vessel 8 and a pressure air pipeline 9 connected to the air booster pump. The pressure air pipeline 9 is located at the pressure vessel cover 1 and extends into the pressure vessel 8. The air booster pump used in this embodiment is a 220V booster pump, and the boost limit value is 1.0Mpa.

[0042] Furthermore, the pressure vessel cover 1 is provided with a secondary safety valve 2 and a primary safety valve 4, the secondary safety valve 2 and the primary safety valve 4 are connected to the pressure vessel internally and connected to the atmosphere externally, the primary safety valve can automatically release pressure when the pressure in the pressure vessel reaches 1.1Mpa, and the secondary safety valve can automatically release pressure when the pressure in the pressure vessel reaches 1.3Mpa.

[0043] Furthermore, two tie rods 7 are arranged on the sides of the pressure vessel 8, and the two tie rods 7 are fixedly mounted on the instrument housing 31 by fasteners 18. A pressure strip 5 located at the top of the pressure vessel 8 (i.e., the upper part of the pressure vessel cover 1) is arranged between the tops of the two tie rods 7, and a pressure strip limiter 3 is arranged on the pressure strip 5. During installation, the two ends of the pressure strip are connected to the two tie rods by bolts, and the pressure strip is fixed to the center of the top cover of the pressure vessel by the pressure strip limiter.

[0044] Furthermore, an insulation layer may be attached to the wall and top of the pressure vessel. The test observation window is made of double-layer high-pressure resistant glass, and the glass pressure resistance limit is greater than 1.5Mpa. In addition, the temperature sensor is located 1 / 3 above the bottom of the pressure vessel, and the pressure sensor is located 3 / 4 above the bottom of the pressure vessel; the pressure sensor is linked to the pressure controller signal, and the temperature sensor is linked to the temperature controller signal. Example

[0045] The materials used in the test are: the aggregate is limestone aggregate produced in Jiangsu Province, and the asphalt is SBS polymer modified asphalt (ID).

[0046] Combined with Figure 1 As shown, the adhesion between limestone aggregate and SBS polymer modified asphalt is tested according to the following steps:

[0047] 1. Sieve the limestone aggregate to be tested, take 5 aggregates of 13.2-19 mm, clean them with water, tie them with a thin wire, and heat them in an oven at 105℃±5℃ for 1h;

[0048] 2. According to the asphalt softening point test method in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), the softening point of SBS polymer modified asphalt is 75°C;

[0049] 3. Lift the heated aggregate particles one by one, immerse them in pre-heated asphalt (155°C) for 45 seconds, then gently take them out so that the aggregate surface is completely and evenly coated with the asphalt film, and then hang the aggregate coated with the asphalt film on the sample rack to cool for 15 minutes;

[0050] 4. According to the softening point of the asphalt used in the test, which is 75°C, the test water temperature is determined to be 125°C;

[0051] 5. According to the test water temperature of 125℃, the saturated vapor pressure of water at this temperature is 232.01Kpa;

[0052] 6. According to the saturated vapor pressure of water, set the value of the pressure controller so that the pressure in the pressure vessel is constant at 252.01Kpa during the test;

[0053] 7. Set the value of the temperature controller to the test water temperature of 125°C;

[0054] 8. Set the value of the time controller to 210s;

[0055] 9. Add water heated to 90°C into the pressure vessel. The amount of water added should be 3cm above the temperature sensor.

[0056] 10. After the aggregate particles have cooled, lift them one by one with a wire and place them on the sample rack, then immerse them in 90°C water and add them into the pressure vessel. Then turn on the main power switch, the air booster pump power switch, and the heating power switch in sequence, and adjust the magnetic stirrer knob to make the water in a micro-motion state. There is no boiling foam in the water during the test;

[0057] 11. After the soaking time is over, quickly open the first and second safety valves to reduce the air pressure in the pressure vessel to atmospheric pressure, then take the aggregate out of the water, cool it, and then put it into a beaker filled with water at room temperature. Visually inspect the degree of peeling of the asphalt film on the surface of the aggregate particles, and determine that the average adhesion between the aggregate and the asphalt is level 5. Example

[0058] Compared with Example 1, the difference of this example is that the raw materials used in the test are: the aggregate is basalt aggregate produced in Chifeng City, Inner Mongolia Autonomous Region, and the asphalt is composite modified asphalt produced by Jiangsu Tiannuo Road Materials Technology Co., Ltd.

[0059] Combined with Figure 1 As shown in the figure, the adhesion between basalt aggregate and composite modified asphalt is tested according to the following steps:

[0060] 1. Screen the basalt aggregate to be tested, take 5 aggregates of 13.2-19 mm, clean them with water, tie them with a thin wire, and heat them in an oven at 105℃±5℃ for 1h;

[0061] 2. According to the asphalt softening point test method in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), the softening point of the composite modified asphalt is 90°C;

[0062] 3. Lift the heated aggregate particles one by one, immerse them in pre-heated asphalt (170°C) for 45 seconds, then gently take them out so that the aggregate surface is completely and evenly coated with the asphalt film, and then hang the aggregate coated with the asphalt film on the sample rack to cool for 15 minutes;

[0063] 4. According to the softening point of the asphalt used in the test, which is 90°C, the test water temperature is determined to be 140°C;

[0064] 5. According to the test water temperature of 140℃, the saturated vapor pressure of water at this temperature is 361.19Kpa;

[0065] 6. According to the saturated vapor pressure of water, set the value of the pressure controller so that the pressure in the pressure vessel is constant at 381.19Kpa during the test;

[0066] 7. Set the value of the temperature controller to the test water temperature of 140°C;

[0067] 8. Set the value of the time controller to 210s;

[0068] 9. Add water heated to 90°C into the pressure vessel. The amount of water added should be 5 cm above the temperature sensor.

[0069] 10. After the aggregate particles have cooled, lift them one by one with a wire and place them on the sample rack, then immerse them in 90°C water and add them into the pressure vessel. Then turn on the main power switch, the air booster pump power switch, and the heating power switch in sequence, and adjust the magnetic stirrer knob to make the water in a micro-motion state. During the test, there is a small amount of boiling foam in the water. At this time, reduce the heating temperature by 1°C;

[0070] 11. After the soaking time is over, quickly open the first and second safety valves to reduce the air pressure in the pressure vessel to atmospheric pressure, then take the aggregate out of the water, cool it, and then put it into a beaker filled with water at room temperature. Visually inspect the degree of peeling of the asphalt film on the surface of the aggregate particles, and determine that the average adhesion between the aggregate and the asphalt is level 4. Example

[0071] Compared with the first embodiment, the present embodiment is different in that: the raw materials used in the test are: the aggregate is granite aggregate produced in Rizhao City, Shandong Province, and the asphalt is heavy traffic road petroleum asphalt 70# produced by Shell.

[0072] Combined with Figure 1 As shown in the figure, the adhesion between granite aggregate and heavy traffic road petroleum asphalt 70# is tested according to the following steps:

[0073] 1. Screen the granite aggregate to be tested, take 5 aggregates of 13.2-19 mm, clean them with water, tie them with a thin wire, and heat them in an oven at 105℃±5℃ for 1h;

[0074] 2. According to the asphalt softening point test method in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), the softening point of heavy traffic road petroleum asphalt 70# is 50℃;

[0075] 3. Lift the heated aggregate particles one by one, immerse them in pre-heated asphalt (127°C) for 45 seconds, then gently take them out so that the aggregate surface is completely and evenly coated with the asphalt film, and then hang the aggregate coated with the asphalt film on the sample rack to cool for 15 minutes;

[0076] 4. According to the softening point of the asphalt used in the test, which is 50°C, the test water temperature is determined to be 100°C;

[0077] 5. According to the test water temperature of 100℃, the saturated vapor pressure of water at this temperature is 101.32Kpa;

[0078] 6. According to the saturated vapor pressure of water, set the value of the pressure controller so that the pressure in the pressure vessel is constant at 121.32Kpa during the test;

[0079] 7. Set the value of the temperature controller to the test water temperature of 100°C;

[0080] 8. Set the value of the time controller to 210s;

[0081] 9. Add water heated to 90°C into the pressure vessel. The amount of water added should be 3cm above the temperature sensor.

[0082] 10. After the aggregate particles have cooled, lift them one by one with a wire and place them on the sample rack, then immerse them in 90°C water and add them into the pressure vessel. Then turn on the main power switch, air booster pump power switch, and heating power switch in sequence, and adjust the magnetic stirrer knob to make the water in a micro-motion state. There is no boiling foam in the water during the test;

[0083] 11. After the soaking time is over, quickly open the first and second safety valves to reduce the air pressure in the pressure vessel to atmospheric pressure, then take the aggregate out of the water, cool it, and then put it into a beaker filled with water at room temperature. Visually inspect the degree of peeling of the asphalt film on the surface of the aggregate particles, and determine that the average adhesion between the aggregate and the asphalt is level 3.

[0084] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A test method for aggregate adhesion based on a pressure vessel, characterized in that: The following steps are involved: (1) Screen the aggregate to be tested, take 5 aggregates with a size of 13.2-19 mm, clean them with water, tie them tightly with a string, and heat them in an oven at 105℃±5℃; (2) According to the asphalt softening point test method in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", test the softening point of the asphalt used in the test; (3) Lift the heated aggregate particles one by one, immerse them in the pre-heated asphalt for 40-50 seconds, and then take them out so that the aggregate surface is completely and evenly coated with the asphalt film. Then hang the aggregate coated with the asphalt film on the sample rack to cool for 10-20 minutes; (4) Determine the test water temperature based on the softening point of the asphalt used in the test. The test water temperature is the softening point of the asphalt + 50°C. (5) According to the test water temperature, look up the table to obtain the saturated vapor pressure of water at that temperature; (6) According to the saturated vapor pressure of water, set the value of the pressure controller so that the pressure in the pressure vessel during the test is constant at the saturated vapor pressure of water + 20Kpa; (7) Set the value of the temperature controller to the test water temperature; (8) Set the value of the time controller; (9) Add water heated to 85-95°C into the pressure vessel. The amount of water added should be 3-5 cm higher than the temperature sensor; (10) After the aggregate particles have cooled, they are lifted one by one with a wire and placed on a sample rack. They are then immersed in water at 85-95°C and added to a pressure vessel. The main power switch, air booster pump power switch, and heating power switch are then turned on in sequence. The stirring device is adjusted to keep the water in a micro-motion state. The heating temperature is fine-tuned by the bubbles that form when the water boils during the test. (11) After the immersion time is over, open the primary and secondary safety valves to reduce the air pressure in the pressure vessel to atmospheric pressure. Then take the aggregate out of the water, cool it, and put it into a beaker filled with water at room temperature. Visually inspect the degree of peeling of the asphalt film on the surface of the aggregate particles. Judge the adhesion between the aggregate and the asphalt based on the degree of peeling.

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