Sampling Asphalt Binders and Emulsions

Performance grading tests on asphalt binder are sensitive: a small amount of solvent, a little overheating, or the wrong container can change a binder's grade. Sampling binder is less about representing a variable material, since a well-mixed tank is fairly uniform, and more about getting the binder from the tank to the laboratory unchanged. The national practice is AASHTO R 66 (ASTM D140), which replaced the older T 40 (California Department of Transportation, 2022¹).

Where Binder Is Sampled

• Supplier terminal or refinery. Agencies that certify suppliers sample at the terminal tank to verify the grade.
• Transport on arrival. A sample taken from the delivery tanker at the plant or job checks what was delivered.
• Plant tank or feed line. A sample from the line feeding the mixer checks the binder actually used in production, after any blending or additives at the plant.
• Distributor truck. For chip seals, tack coats and other sprayed treatments, the distributor is sampled from its sampling valve.

Most tanks and transports have a dedicated sampling valve. Before taking the sample, the valve is opened and a quantity of binder is drawn off and discarded, to clear material that has been sitting in the line. Samples are never dipped from an open hatch with a container that has been in contact with anything else (California Department of Transportation, 2022¹).

Containers

• Asphalt binders are sampled into new, clean, unlined metal cans with tight lids, usually about 1 L (1 quart). Cans are not washed with solvent and not reused.
• Emulsions are sampled into clean, wide-mouth plastic containers with screw caps. They are not put in metal cans, which can corrode and break the emulsion, or in glass.
• Cutbacks follow the binder practice but need tight seals because their solvents evaporate.

Containers are filled nearly full, sealed at once, and wiped clean on the outside with a dry cloth, never with solvent. Each is labeled on the body, not the lid, with the grade, supplier, tank or transport, date, time and sampler (California Department of Transportation, 2022¹).

Handling

• Emulsions must not freeze, and should be tested within the time the specification allows, because they can settle or break in storage.
• Binder samples are not repeatedly reheated. Each reheating ages the binder and can push it toward a stiffer grade. Laboratories heat a sample once and pour all the test specimens they need at that time.
• Samples are protected from contamination by dust, water or oil during transport.

Related Articles

• Superpave Performance Grading
• Emulsified Asphalt
• Asphalt Safety

Standard Practices

• AASHTO R 66, ASTM D140: Sampling asphalt materials

@misc{pavint-sampling-asphalt-binders-and-emulsions,
  author = {{Pavement Interactive}},
  title = {Sampling Asphalt Binders and Emulsions},
  year = {2026},
  publisher = {HeadLight},
  howpublished = {\url{https://pavementinteractive.org/reference-desk/testing/sampling/sampling-asphalt-binders-and-emulsions/}},
  note = {Accessed [date]}
}