GB/T 4510-2017 Petroleum asphalt brittleness point determination method — Fraass method

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Card type: Test method

1. Method number / full title / English title / replacement relationship

• Standard number: GB/T 4510-2017
• Chinese title: Petroleum asphalt brittleness point determination method — Fraass method
• English title: Test method for breaking point of bitumen—Fraass method
• Replacement relationship: replaces GB/T 4510-2006 "Petroleum asphalt brittleness point determination method — Fraass method"
• Previous versions: GB/T 4510-1984, GB/T 4510-2006
• Publication/implementation: published on 2017-07-31, implemented on 2018-02-01
• Custodian: National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280)
• Drafting organizations: Research Institute of Qilu Branch, China Petroleum & Chemical Corporation (responsible); Fushun Research Institute of Petroleum and Petrochemicals, China Petroleum & Chemical Corporation; Research Institute of Petroleum Processing, China Petroleum & Chemical Corporation; CNOOC (Qingdao) Heavy Oil Processing Engineering Technology Research Center Co., Ltd. (participating)
• Main drafters: Yao Dehong, Chen Heling, Chang Yuyan, Zhu Chuanrong, Ning Aimin, Wang Cuihong, Li Fuqi

2. Scope of application and non-applicability

• This standard specifies a method for determining the brittleness point of petroleum asphalt materials by the Fraass method.
• This standard is applicable to the determination of the brittleness point of asphalt materials by the Fraass method.
• Not applicable: not provided in the available source.

3. Method principle

An asphalt sample is uniformly coated on a flat thin steel strip, and under specified conditions it is continuously cooled and repeatedly bent until the asphalt sample coating cracks; the temperature at which cracking first occurs is reported as the Fraass brittleness point.

4. Reagents and materials (purity / preparation)

• Ethanol or an ethanol analogue (5.7): added to a vacuum flask, or added through funnel 9 (see Figure 1) into outer test tube 4 (see Figure 1).
• Dry ice or other coolant (5.8): dry ice or other coolant is added through funnel 9 (see Figure 1) into ethanol or its analogue.
• Desiccant: inner test tube 5 and cylindrical tube 1 contain a small amount of desiccant such as calcium chloride or silica gel (5.2.3).
• Cleaning solvent (6.3.1): acetone, cyclohexane, etc.
• Purity requirements: not provided in the available source.

5. Apparatus and equipment

• 5.1 Thin steel strip: material is 70 spring steel or another similar type, which does not deform after repeated bending; length 41.00 mm±0.05 mm, width 20.0 mm±0.2 mm, thickness 0.15 mm±0.02 mm; it should be stored flat in a dry and clean place; those with obvious bending deformation or rust visible to the eye should be discarded.
• 5.2 Fraass brittleness point apparatus
  • 5.2.1 Structural diagram of the brittleness point apparatus: the manual Fraass brittleness point apparatus is as shown in Figure 1, and consists of the components described in 5.2.2 to 5.2.4; semi-automatic or fully automatic brittleness point apparatuses that meet the test conditions specified in this standard are permitted, and their specific structural diagrams are given in the corresponding instrument operating instructions.
  • 5.2.2 Bender: consists of two concentric circular tubes, inner and outer, made of a material with a low coefficient of thermal expansion (linear expansion coefficient: <40×10⁻⁶ 1/K) and poor thermal conductivity [thermal conductivity: <0.3 W/(m·K)]; during assembly, the inner tube can move longitudinally inside the outer tube, and the gap between the two tubes should not exceed 1 mm; a steel clamp is installed at the lower end of each circular tube, and the two clamps should be in the same plane, parallel to the axis of the tubes; the positioning screw is tightened to prevent the inner tube from rotating; a narrow slit is left in the inner tube so that the mercury bulb of the thermometer is exposed, and the mercury bulb should be exactly located at the middle part behind the unbent test strip; at the upper end, a mechanical lifter composed of a hard metal cone with a crank and a positioning screw is installed; the maximum distance between the two clamps is 40.0 mm±0.1 mm, and turning the crank 11 turns can shorten the distance between the two clamps by 3.5 mm±0.1 mm; semi-automatic brittleness point apparatuses with a built-in motor-driven cam disk or fully automatic brittleness point apparatuses are permitted.
  • 5.2.3 Cooling device: includes inner test tube 5 (inner diameter 35 mm, length 210 mm), which is fixed off-axis by means of rubber stopper 7 inside the larger outer test tube 4 (inner diameter 57.5 mm±2.5 mm, length 200 mm), and rubber stopper 7 is provided with small funnel 9; outer test tube 4 is fixed on cylindrical glass cylinder 1 with rubber stopper or cork stopper 6; inner test tube 5 and cylindrical cylinder 1 contain a small amount of desiccant such as calcium chloride or silica gel; the bender is fixed inside inner test tube 5 with rubber stopper 8; outer test tube 4 and cylindrical cylinder 1 may be replaced by an unsilvered vacuum flask meeting the requirements of Figure 1; all components of the cooling device should be ensured to be vertical; the suitable bath liquid for the vacuum flask may be ethanol or an ethanol analogue; semi-automatic and fully automatic brittleness point apparatuses with automatic control of temperature decrease are permitted.
  • 5.2.4 Thermometer: a mercury thermometer meeting the technical requirements for GB-43 brittleness point in GB/T 514, with a measurement range of −38 ℃ to +30 ℃; other temperature measuring instruments that have been calibrated and meet this requirement may also be used; fully automatic brittleness point apparatuses with automatic display of the brittleness point temperature are permitted; record the correction value of the thermometer and correct the indicated value.
• 5.3 Heater: consists of a heat source, a heating plate and a stand; a flat metal heating plate of length 160 mm, width 80 mm, and thickness 3 mm is placed on a stand that can be adjusted to level, and a heat source with adjustable temperature is provided below the heating plate.
• 5.4 Balance: minimum division value is 0.01 g.
• 5.5 Porcelain dish or metal dish: when heating the sample, select an appropriate porcelain dish or metal dish according to the amount of sample.
• 5.6 Sieve: metal sieve with sieve openings of 0.3 mm to 0.6 mm.
• 5.7 Ethanol or an ethanol analogue.
• 5.8 Dry ice or other coolant.

6. Recommended operating conditions

• Cooling rate: 1 ℃/(60±5) s; when decreasing by 1 ℃, the maximum time deviation and average time deviation must not exceed ±5 s per minute (7.1).
• Starting bending temperature: begin bending when the temperature reaches (10±2) ℃ above the expected brittleness point of the test strip (7.1).
• Bending operation: turn the crank at a speed of r/s until the distance between the clamps is shortened by 3.5 mm±0.1 mm; if there is no crack, immediately turn back in the opposite direction at the same speed to extend the test strip; after the bender returns to the initial position and is held for (38±5) s, repeat the bending and extending operations so that the test strip is bent and extended 1 times per minute until a crack appears (7.1).
• Test strip placement: place at a temperature at least 15 ℃ above the expected brittleness point for 30 min to 240 min, and protect the test strip from dust contamination (7.1).
• Cooling bath: inject at least 100 mm of ethanol or its analogue into outer test tube 4 (7.1).
• Semi-automatic/automatic brittleness point apparatus: operate according to the manufacturer's operating instructions, the cooling rate is always maintained at 1 ℃/(60±5) s, and the bending frequency should also meet the above requirements (7.1).
• During the test, it is not permitted to take the bender out of the inner test tube for observation (7.1).

7. Sampling and sample preparation

• 6.1 Sampling: obtain a representative uniform sample free from contamination in accordance with GB/T 11147.
• 6.2 Sample treatment:
  • When heating the sample, an appropriate heating temperature should be selected. For asphalt with a softening point lower than 80 ℃, the heating temperature should not be higher than 80 ℃ to 90 ℃ of the estimated softening point; for petroleum asphalt with a softening point higher than 80 ℃, if the heating temperature cannot be accurately determined, it should be heated to the lowest temperature at which there are no bubbles in the sample; under no circumstances may the heating temperature of the sample exceed 110 ℃ of its softening point; for polymer-modified asphalt, regardless of the softening point, the heating temperature must not exceed 200 ℃.
  • The heating time should be such that the sample flows sufficiently, and it should be stirred continuously during heating to avoid local overheating; when the sample contains water, stir continuously until the water is removed; when it contains impurities, filter through a sieve; during preparation, the sample must not undergo changes in properties such as aging or decomposition.
• 6.3 Test strip preparation:
  • 6.3.1 Thin steel strip preparation: clean it thoroughly with solvent (acetone, cyclohexane, etc.), dry it, and weigh accurately to 0.01 g; thin steel strips that are bent or rusted must not be used.
  • 6.3.2 Test strip preparation: weigh 0.41 g±0.01 g of asphalt sample onto a clean thin steel strip of known mass; when using a heater to melt the sample, place the test strip on the heating plate and heat slowly, and when the sample just begins to flow, hold the heating plate with tweezers and swing it back and forth and left and right until the test strip is completely coated with the sample; for samples with a high softening point or when using a fixed heating plate, a clean fine needle may be used to spread it or cellophane may be used to separate and press it so that the test strip is completely coated with the sample, and then a flame of suitable size is carefully passed over the test strip to remove bubbles, avoiding local overheating of the test strip during bubble removal; when the test strip is heated on the heating plate, the temperature must not exceed the asphalt softening point by 80 ℃, and for polymer-modified asphalt the temperature must not exceed 200 ℃; for samples that are difficult to prepare at the above temperatures, the temperature may be appropriately increased until the sample can flow; if the apparatus is equipped with special pressing equipment, the pressed sample sheet may be attached to the thin steel strip and slightly heated so that it bonds well to the thin steel strip; the finally obtained test strip has a smooth surface, and the preparation time for each test strip must not exceed 10 min; after the prepared test strip is cooled to room temperature, weigh it again, and the sample mass should meet the requirements of 0.41 g±0.01 g, otherwise this test strip is discarded and not used.

8. Analytical procedure

• 7.1 Determination method:
  • Place the test strip at a temperature at least 15 ℃ above the expected brittleness point for 30 min to 240 min, and protect the test strip from dust contamination.
  • Inject at least 100 mm of ethanol or its analogue into outer test tube 4, and carefully place the slightly bent test strip between the two clamps of the bender; if the test strip cracks during placement, discard it and do not use it.
  • Install the bender in inner test tube 5 of the cooling device, insert the thermometer, and make the mercury bulb of the thermometer be located at the middle position behind the test strip.
  • Add dry ice into ethanol or its analogues through a funnel 9, controlling the addition rate so that after 3 min the cooling bath reaches a cooling rate of 1 ℃/(60±5) s; when lowering 1 ℃, the maximum time deviation and average time deviation must not exceed ±5 s per minute.
  • When the temperature reaches above the expected brittle point of the test specimen (10±2) ℃, begin turning the crank at a speed of r/s until the clamp distance is shortened by 3.5 mm±0.1 mm, while observing whether the specimen cracks when bent; if no crack, immediately turn the crank back in the reverse direction at the same speed to extend the specimen; after the bender returns to the initial position and is held (38±5) s, repeat the bending and extending operations so that the specimen is bent and extended 1 times per minute, until a crack appears; record this temperature as the brittle point measured value, accurate to 1 ℃.
  • When repeatedly measuring multiple test specimens, each measurement should allow the temperature of ethanol or its analogues to rise back to the initial test temperature.
  • During the test, it is not allowed to remove the bender from the inner test tube for observation.
  • When using a semi-automatic or automatic brittle point apparatus, operate according to the manufacturer's instructions, the cooling rate is always maintained at 1 ℃/(60±5) s, and the bending frequency should also meet the above requirements.
• 7.2 Determination of Fraass brittle point:
  • Measure the first test specimen to obtain the approximate brittle point value of the sample T₁.
  • If T₁ is obtained from initial bending above T₁ (10±2) ℃, record it as T₀; take another test specimen and repeat the measurement, with initial bending above T₀ (10±2) ℃, to obtain the brittle point measured value, recorded as T₁.
  • If T₁ is not obtained from initial bending above T₁ (10±2) ℃, take two more test specimens and repeat the measurement, with initial bending above T₁ (10±2) ℃, to obtain the brittle point measured values, recorded respectively as T₂, T₃.
• 7.3 Maximum range of valid measured values:
  • When the difference between two measured values (T₀, T₁) or (T₂, T₃) is not greater than 3 ℃, then (T₀, T₁) or (T₂, T₃) are valid values.
  • If the difference between (T₀, T₁) or (T₂, T₃) is greater than 3 ℃, take two more test specimens for additional measurement, with initial bending above T₁ (10±2) ℃, to obtain the brittle point measured values, recorded respectively as T₄, T₅; if the difference between (T₄, T₅) is not greater than 3 ℃, then the values (T₄, T₅) are valid.
  • If the difference between (T₄, T₅) is still greater than 3 ℃, then consider the four values (T₀, T₁, T₄, T₅) or the four values (T₂, T₃, T₄, T₅) as valid, and indicate the value range of the valid results.
  • Note: In the original text 7.2, 7.3, the subscripts of the symbols T₁, T₀, T₂, T₃, T₄, T₅ and some expressions have source-text extraction doubts, requires confirmation against the source standard (source-text extraction).

9. Qualitative and Quantitative and Calculation Formulas

• Result calculation (Chapter 8): Take the average of two or four valid values as the reported value of the Fraass brittle point, in degrees Celsius (℃), and the result is rounded to an integer.
• Calculation formula: not provided in the available source.

10. Precision

• 9.1 Repeatability: the difference between two test results obtained by the same operator, using the same instrument, according to the same test method, on the same sample in continuous measurements; for road asphalt and building asphalt, the difference between repeatability test results should not exceed 3 ℃.
• 9.2 Reproducibility: the difference between single, independent test results obtained in different laboratories, by different operators, using different instruments, according to the same test method, on the same sample; for road asphalt and building asphalt, the difference between reproducibility test results should not exceed 6 ℃.
• 9.3 Precision for polymer-modified asphalt: This standard does not currently specify precision for polymer-modified asphalt.
• Note: In the original text 9.1, 9.2, there is a suspected source-text extraction misalignment in the arrangement of definition sentences and index sentences, requires confirmation against the source standard (source-text extraction).

11. Report

Chapter 10 Test report: The original record should at least include the following information:

• a) Sample type and name;
• b) Reference to this standard number;
• c) Type of instrument used (manual, semi-automatic or automatic);
• d) Test results;
• e) Any deviation from the specified procedure;
• f) Test date.

12. Normative References

• GB/T 514 Technical conditions for glass liquid thermometers for petroleum product testing
• GB/T 11147 Asphalt sampling method
• GB/T 1.1—2009 (mentioned in the foreword, this standard is drafted according to the rules given therein)

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