SH/T 0774-2005 Accelerated Aging Test Method for Asphalt (PAV Method)

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Card type: Test method

1. Method number / Full name / English name / Replacement relationship

• Method number: SH/T 0774—2005
• Chinese full name: Accelerated Aging Test Method for Asphalt (PAV Method)
• English name: Standard practice for accelerated aging of asphalt binder using a pressurized aging vessel (PAV)
• Replacement relationship: This standard is first published (original text: This standard is first published). Modified adoption of ASTM D 6521-00 "Standard Practice for Accelerated Aging of Asphalt Binder Using a Pressurized Aging Vessel (PAV) (PAV)" (English version), and redrafted according to ASTM D 6521-00.
• Main differences from ASTM D 6521-00 (original foreword):
  • For referenced documents, where ASTM standards have been converted to corresponding Chinese standards, the Chinese standard names are used.
  • Replace ASTM D8 "Terminology Relating to Road and Pavement Materials" in the normative references of ASTM D 6521-00 with SH/T 0652 "Petroleum Asphalt Terminology".
  • Change the layout format of the ASTM standard to conform to the layout format of Chinese standards.
  • Since China currently does not adopt PG grading, content related to PG grading in the original standard text has been deleted.
• Publication/Implementation: Published on 2005-11-28, implemented on 2006-06-01; issuing authority: National Development and Reform Commission of the People's Republic of China.
• Technical administration: Technical administration by the Heavy Oil Research Institute of China University of Petroleum (East China); drafting organizations: Heavy Oil Research Institute of China University of Petroleum (East China), Wuhan University of Technology; main drafters: Zhang Xiaoying, Zhang Yonghe, Yu Jianying, Wu Shaopeng.

2. Scope of application and non-applicability

• 1.1 This test method uses high temperature and compressed air to accelerate the aging (oxidation) of asphalt, with the purpose of simulating the oxidative aging that occurs during road service. This method cannot accurately simulate the relative rate of aging.
• Sample source: The sample used in this method is the residue obtained from the SH/T 0736—2003 "Standard Test Method for Effect of Heat and Air on a Moving Film of Asphalt (Rolling Thin-Film Oven Test) (RTFOT)" test.
• Not applicable: Modified asphalts that undergo phase separation or surface skinning under the RTFOT test conditions may also undergo similar situations under the PAV test conditions, so this method may not be applicable to such modified asphalts. Whether this method is applicable to asphalt containing fine particles requires confirmation against the source standard.
• 1.2 This standard is used to evaluate the anti-oxidative aging ability of different asphalts under test temperature and pressure conditions, but it cannot explain the influence of mixture factors or the influence of asphalt under actual service conditions on aging.
• 1.3 This standard uses International System of Units (SI) units.
• 1.4 This standard does not involve safety regulations related to use, and users of the standard are responsible for establishing appropriate safety application procedures before use.

3. Method principle

• 4 Method overview: Place the residue from SH/T 0736 "Standard Test Method for Effect of Heat and Air on a Moving Film of Asphalt (Rolling Thin-Film Oven Test) (RTFOT)" in a stainless steel pan of GB/T 5304 "Standard Test Method for Effect of Heat and Air on Asphaltic Materials (Thin-Film Oven Test) (TFOT)" according to the asphalt film thickness specified in the test, then place it in a pressure vessel with an air pressure of 2.1MPa, and age at the selected aging temperature for 20h. Finally, the residue is subjected to vacuum degassing.
• 5 Significance and use:
  • 5.1 This test method is used to simulate the oxidative aging that occurs during the use of asphalt. The properties of the residue obtained by this standard can predict the physical and chemical properties of asphalt after several years of use.
  • 5.2 For asphalts of different grades or different sources, there is no direct correspondence between the aging time and temperature in this test and the aging time and temperature in road use.
  • 5.3 Under a certain same temperature and pressure condition, two asphalts may have similar aging rates, but under another test condition, the aging rates may differ. Therefore, under the PAV condition, the relative aging rates of some asphalts may be significantly different from the actual relative rates during use. (This paragraph in the original text has heavy source-text extraction noise, semantics require confirmation against the source standard (source-text extraction))

4. Reagents and materials (purity / preparation)

• 7 Test material: commercially bottled compressed air or equivalent.
• Other reagents: not provided in the available source.

5. Instruments and equipment

• 6.1 The equipment system consists of a pressure vessel, pressure control equipment, temperature control equipment, pressure and temperature measurement equipment, and a temperature and pressure recording system (see Figure 1).
• 6.1.1 Pressure vessel: a stainless steel vessel that can be used for a long time under a pressure of 2.1MPa±0.1MPa and a temperature of 90℃~110℃, and its internal dimensions should be sufficient to accommodate pan loading and 10 pans of TFOT. The vessel includes a pan rack, which can horizontally place 10 pans so that the asphalt film thickness is reasonably uniform. The pan rack should allow the pans and asphalt to be easily placed and removed at the aging temperature. (The original text here has heavy source-text extraction noise, the dimensional description requires confirmation against the source standard (source-text extraction))
• 6.1.2 Pressure control equipment:
  • 6.1.2.1 Pressure reducing valve: prevents the pressure in the vessel from exceeding the design pressure of the vessel. Under no circumstances during aging may the pressure in the vessel exceed 2.5MPa. (The number in the original text is suspected to be "V.SMP", requires confirmation against the source standard (source-text extraction))
  • 6.1.2.2 Pressure regulating system: maintains the vessel pressure at 2.1MPa±0.1MPa, controls the pressure in the vessel at ±0.02MPa, and... (The original text here has heavy source-text extraction noise, requires confirmation against the source standard (source-text extraction))
  • 6.1.2.3 Slow gas release: after exceeding, can be reduced from 2.1MPa to local atmospheric pressure within 8min~15min. (The original text has heavy source-text extraction noise, requires confirmation against the source standard (source-text extraction))
• 6.1.3 Temperature control equipment: temperature control equipment that can stabilize the internal temperature of the pressure vessel at ±0.5℃ of the aging temperature.
  • 6.1.3.1 Heating equipment of a forced draft oven or liquid bath: after the sample pans and pan rack are placed in the vessel and before pressurization, its heating equipment can reach the aging temperature within 2h and maintain the temperature within ±0.5℃ of the aging temperature. If an oven is used, it should be large enough so that the vessel is placed in the oven and the blown air can freely circulate around the vessel. There should be a support in the oven that can horizontally place the pressure vessel and temperature display.
  • 6.1.3.2 Pressure vessel with temperature control system: after the sample pans and pan rack are placed in the vessel, the vessel loaded with the vessel can, within 2h of the heating equipment, restore the pre-aging temperature determined in 9.3 and maintain the pressure within ±0.5℃ required for aging. Note: The pressure vessel must be preheated to the aging temperature within the required 2h.
• 6.1.4 Temperature and pressure measurement equipment:
  • 6.1.4.1 Platinum resistance thermometer: a platinum resistance thermometer accurate to 1℃, meeting or equivalent to the specification of ASTM E 1137 (IP0 751), measuring the temperature inside the pressure vessel. Calibrate the RTD system with a separate instrument or circuit. (The original text "[garbled tolerance wording] 1°C" requires confirmation against the source standard (source-text extraction))
  • 6.1.4.2 Recorder: a bench-top recorder or other equipment with similar functions, capable of recording the temperature throughout the aging process with an accuracy of 0.3. Alternatively, a temperature recording device accurate to 0.1℃ that records only the maximum and minimum temperatures may be used. (The original text "[garbled prefix]03 accuracy" requires confirmation against the source standard (source-text extraction))
  • 6.1.4.3 Pressure gauge: capable of accurately measuring the pressure inside the pressure vessel. (The original text source-text extraction has heavy noise, requires confirmation against the source standard (source-text extraction))
• 6.2 Stainless steel pan: a stainless steel pan of TFOT meeting the requirements of the GB/T 5304 standard. (The original text "SB/T 5304" requires confirmation against the source standard (source-text extraction))
• 6.3 Balance: ±0.1g.
• 6.4 Vacuum oven: precision... in cases where a vacuum oven is used, capable of maintaining a temperature of 180℃, with an absolute pressure of 15kPa±0.1kPa... (The original text source-text extraction has heavy noise, requires confirmation against the source standard (source-text extraction)). If there is no vacuum oven, the pressure vessel itself may be used instead of the vacuum oven.
• 6.5 Vacuum system: a vacuum system capable of generating and maintaining an absolute pressure of 15kPa. The vacuum system should include a vacuum pump, a vacuum chamber, and a vacuum gauge. (The original text "5kPa" requires confirmation against the source standard (source-text extraction))
• Figure 1 PAV Schematic diagram of the test system; Figure 2 PAV Schematic diagram of the positions of the sample pan and temperature sensor (RTD) (unit: mm; a is the horizontal control point of the pan, and there are three or more support points of the device; c should be greater than 12mm; the difference in distance should be controlled at ±0.05mm, etc., source-text extraction has heavy noise, requires confirmation against the source standard (source-text extraction)).

6. Recommended operating conditions

• Aging temperature: set based on climatic conditions, and may be one of 90℃, 100℃, 110℃. For asphalt with a 7-day average maximum design temperature higher than 64℃ or higher, except in desert climate conditions where it is 110℃, the aging temperature under other conditions is 100℃. (The original text "90°CC, 100[unreadable unit], 110[unreadable unit]" requires confirmation against the source standard (source-text extraction))
• Note 2: For a three-temperature-controlled oven, the vessel may be preheated to 10℃~15℃ above the aging temperature to reduce the decrease in PAV temperature during loading and to reduce the time to reach equilibrium temperature and to rise to the aging temperature after loading. (The original text "[garbled temperature-control wording]" requires confirmation against the source standard (source-text extraction))
• Note 3: Select the PAV aging temperature according to different climatic zones. Heating temperature exceeding 115℃ should be avoided, as excessively high temperature may cause changes in the chemical properties of asphalt.
• Pressure: 2.1MPa±0.1MPa air pressure.
• Aging time: 20h±10min.
• Pressure release: reduce from 2.1MPa to local atmospheric pressure within 8min~15min.

7. Sampling and specimen preparation

• 10.1 Perform aging test on asphalt according to SH/T 0736—2003 "Standard Test Method for Effect of Heat and Air on a Moving Film of Asphalt (Rolling Thin-Film Oven Test) (RTFOT)".
• 10.2 Pour the residues from each bottle of RTFOT into one container, mix uniformly, and then perform PAV aging; according to 10.4, pour the residue into TFOT pans, or cool the residue in the container to room temperature, cover with a lid, place at room temperature, and later perform PAV aging. Asphalt at room temperature should be heated until it flows before being poured into the TFOT pans.
• 10.4 Place the TFOT pan on the balance, add 50g±0.5g of asphalt into the pan, and spread it into an asphalt film approximately 3.2mm thick.
• Note: Measurement of mass change is not part of the standard procedure. The mass increase as an aging result is obviously caused by the asphalt absorbing air under pressure, so measuring mass change is meaningless.

8. Analytical Procedure

• 10.3 Place the pan and rack inside the pressure vessel. If an oven is used, place the pressure vessel in the oven, select the aging temperature, and preheat the pressure vessel to the selected aging temperature. If a pressure vessel with a temperature controller is used, select the aging temperature and preheat the pressure vessel according to the equipment instructions.
• 10.5 If a container heated by an oven is preheated to a temperature higher than desired, reset the temperature on the oven to achieve the aging temperature.
• 10.6 Operate as quickly as possible according to the contents described in 10.7 and 10.8, avoiding cooling of the container and pan.
• 10.7 Place the pan containing the sample on the pan rack (during a single aging process, pans of asphalt from different sources and of different grades may be placed in the same pressure vessel). Place the pan containing the test sample and the rack into the pressure vessel, and close the pressure vessel (unused rack slots do not need empty pans).
• 10.8 If an oven is used, place the closed pressure vessel containing the sample into the oven. Set the oven temperature, connect the temperature sensor of the container, and connect the compressed air line to the fitting on the outside of the pressure vessel according to the requirements of the container design and oven structure.
• 10.9 Keep the pressure vessel in the oven until the temperature inside it reaches the specified temperature minus the value determined in 9.3, introduce air at a pressure of 2.1MPa±0.1MPa, and start timing the aging procedure. If a temperature controller is used, after preheating the container, introduce 2.1MPa±0.1MPa compressed air and start timing the aging procedure according to the equipment instructions.
  • Note 1: A pressure exceeding 2.1MPa does not substantially increase the aging rate, so there is no reason to increase the pressure.
  • Note 2: Once calibrated, the temperature inside the pressure vessel equilibrates rapidly. SH/T 0736 In the asphalt rotating thin film oven test method, the asphalt residue that has undergone 163℃ aging undergoes almost no aging at atmospheric pressure from the preheating temperature to the aging temperature. Therefore, the pressurization time (excluding the preheating time at room temperature) is also the aging time.
• 10.10 Maintain the temperature and pressure inside the pressure vessel at 20h±10min.
• 10.11 During the aging stage, if any of the following conditions occur, the aging process is invalid and the test sample shall be discarded:
  • (1) After loading the rack and pan 2h, the temperature inside the container has not yet reached the desired temperature for pressurization;
  • (2) The total time during which the temperature displayed by the temperature recording device is higher or lower than the target aging temperature ±0.5℃ exceeds 60min;
  • (3) At the end stage of the aging procedure, the pressure exceeds the design range in 10.9;
  • (4) If the equipment can only record the maximum and minimum temperatures, and during the aging period of 20h, the recorded temperature variation exceeds the aging temperature ±0.5℃.
• 10.12 When the aging of 20h ends, use the vent valve to begin slowly reducing the internal pressure of PAV. The vent valve is preset to an opening such that the internal and external pressures of PAV equilibrate within 8min~15min, avoiding excessive bubbles and foam in the asphalt. The aging time of 20h does not include the time for releasing and equilibrating pressure.
• 10.13 Perform vacuum degassing on the aged sample:
  • 10.13.1 Remove the rack and pan from PAV, and place the pan in an oven set at 163℃ to heat for 15min±1min. Note: The residue of PAV may be heated and stirred in a TFOT pan at a temperature of 163℃ to remove bubbles. This helps avoid oxidation and volatilization losses that cause sample hardening. During heating, cover the sample, and occasionally stir and scrape the bottom of the pan to ensure sample uniformity.
  • 10.13.2 Preheat the vacuum oven to 170℃±5℃.
  • 10.13.3 Remove the pan from the oven, pour the hot residue containing a single sample separately into a container. A container of suitable size shall be selected so that the thickness of the residue in the container is between 15mm~40mm. After scraping the last pan, transfer the container into the vacuum oven within 1min. Keep the vacuum oven at 170℃±5℃ for 10min±1min.
  • 10.13.4 Reduce the pressure as quickly as possible to an absolute pressure of 15kPa±2.5kPa, and maintain constant pressure for 30min±1min. Release the vacuum and remove the container. If bubbles remain on the surface, use a hot knife to remove the bubbles on the surface of the residue of PAV.
• 10.14 If other tests are not immediately performed on the degassed residue of PAV, the container of residue of PAV may be covered and placed at room temperature for further testing.

9. Qualitative and Quantitative and Calculation Formulas

• No calculation formula is provided in the available source. This standard is an aging test method and only specifies the test procedure; it does not involve test indicators of material performance (see 12.1).

10. Precision

• 12.1 This standard is an aging test method and only specifies the test procedure; it does not involve test indicators of material performance, and therefore there is no precision requirement.
• 12 Precision and bias: no specific provisions on bias are provided in the available source.

11. Report

Report the following information:

• 11.1 Sample number.
• 11.2 Aging temperature, accurate to 0.5℃.
• 11.3 Record the maximum and minimum aging temperatures, accurate to 0.1℃.
• 11.4 The total time during the aging process when the aging temperature is outside the specified range, accurate to min.
• 11.5 Total aging time, in units of h and min.
• 11.6 During the processing of asphalt, if a temperature higher than 163℃ is required, record the heating temperature and heating time.

12. Referenced Documents

• GB/T 5304 Standard Test Method for Thin Film Oven Test of Petroleum Asphalt
• SH/T 0652 Terminology for Petroleum Asphalt
• SH/T 0736 Standard Test Method for Rotating Thin Film Oven Test of Asphalt
• ASTM D 4753 Specification for Evaluation, Selection, and Classification of Balances and Scales Used in Tests of Soils, Rocks, and Construction Materials (Specification for Evaluating, Selecting and Specifying Balances and Scales for Use in Soil Rock and Construction Materials Testing)
• ASTM E 220 Standard Test Method for Calibration of Thermocouples by Comparison Techniques (Test Method for Calibration of Thermocouples by Comparison techniques)
• ASTM E 1137 Specification for Industrial Platinum Resistance Thermometers (Specification for Industrial Platinum Resistance Thermometers)
• Note: SH/T 0736 is cited in the main text as SH/T 0736—2003.

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick Reference Q&A