Reading a Bitumen Certificate of Analysis
What each row measures, which test method produces it, and what an out-of-range value physically tells you about the parcel. Written so a buyer without a laboratory can still tell a sound certificate from a doubtful one.
Certificate rows for penetration grade bitumen
Applies to grades such as 20/30, 40/50, 50/70, 60/70, 80/100, 85/100, 120/150 and 200/300.
| Row | Method | What an out-of-range value tells you |
|---|---|---|
| Penetration @ 25 °C | ASTM D5 | Reported in dmm, tenths of a millimetre. Conditions are 100 g for 5 s. Outside the window means the wrong grade was loaded or the blend missed target |
| Softening point | ASTM D36 | Ring and ball. Well above the minimum with penetration at the low end suggests material that has already been heated hard, or older stock |
| Ductility @ 25 °C | ASTM D113 | Drawn at 5 cm per minute. A low result on a paving grade indicates a binder that will crack rather than flex, and is a stronger warning than a marginal penetration figure |
| Density / relative density | ASTM D70 | Below about 1.01 g/cm³ suggests cutting with a lighter fraction. It also changes every volume conversion on the shipment |
| Solubility in trichloroethylene | ASTM D2042 | Below 99.0 % means non-bituminous matter is present, usually mineral filler. The most direct test for adulteration on the certificate |
| Flash point | ASTM D92 | Cleveland open cup. A low result indicates cutter stock or solvent carry-over, and narrows the safe heating margin |
| Loss on heating and retained penetration | ASTM D6 or D1754, then D5 | How much softness survives mixing. A low retained figure means the binder hardens fast on the road even though it left the tank in specification |
| Spot test | AASHTO T102 | Should read negative. Positive indicates the material was cracked or overheated during processing |
Certificate rows for PG bitumen
A performance grade certificate reports the binder in three states. Knowing which state each row belongs to is what makes the document checkable.
| Row | Method | What it governs |
|---|---|---|
| Flash point | AASHTO T48 | Safe handling margin, minimum 230 °C |
| Rotational viscosity @ 135 °C | AASHTO T316 | Pumpability and mixing. The 3 Pa·s ceiling exists so the binder can be handled with conventional plant |
| Dynamic shear, original binder | AASHTO T315 | Rutting resistance at the start of service. G*/sinδ, minimum 1.00 kPa, at the upper grade temperature |
| Dynamic shear, RTFOT residue | AASHTO T240 then T315 | Rutting resistance after mixing and laydown. Minimum 2.20 kPa at the same temperature |
| Dynamic shear, PAV residue | AASHTO R28 then T315 | Fatigue cracking after five to ten years of ageing. Maximum 5000 kPa at the intermediate temperature |
| Creep stiffness, bending beam | AASHTO T313 | Thermal cracking. Maximum 300 MPa. A figure in the thousands is a transcription error copied from the dynamic shear row |
| m-value, bending beam | AASHTO T313 | How fast the binder sheds thermal stress. Minimum 0.300, and the more common of the two low-temperature failures |
Eight things worth querying before acceptance
Questions buyers ask about certificates
What does a negative spot test mean?
It means the material passed. The spot test, AASHTO T102, detects whether the bitumen has been cracked or overheated during processing, which shows up as a dark ring when a drop is placed on filter paper with a solvent. A negative result is the required outcome; a positive result indicates thermally damaged material that will age faster and behave unpredictably in the mix.
What does dmm mean on a penetration result?
Tenths of a millimetre. A penetration of 65 dmm means the standard needle sank 6.5 mm into the sample under 100 grams for 5 seconds at 25 degrees. It is not millimetres, and reading it as millimetres makes every grade look ten times softer than it is. The convention comes from the test method reporting in units of 0.1 mm.
What does solubility in trichloroethylene actually test for?
Adulteration. Bitumen dissolves almost completely in trichloroethylene; mineral filler, sand and most other non-bituminous additions do not. A result below 99.0 per cent means something insoluble is present, and the shortfall is a direct measure of how much. It is the most straightforward test on the certificate for detecting a cut or extended parcel.
Why does the certificate show two dynamic shear results at the same temperature?
Because the binder is tested twice: once as delivered and once after the rolling thin film oven test, which simulates the hardening that happens during mixing and laydown. The original binder must reach at least 1.00 kPa and the aged residue at least 2.20 kPa. Seeing only one of the two means the certificate is incomplete.
Can I ask for a third-party inspection certificate?
Yes, and it is normal practice where a letter of credit requires it. SGS, Intertek and Bureau Veritas all provide load-port sampling and analysis. The cost is normally to the buyer account unless the contract states otherwise, and the appointment should be made before loading rather than after, since a sample drawn at destination proves far less about what was shipped.
Other technical references
Want a sample certificate before you order?
Send the grade and quantity you are considering and a representative certificate of analysis comes back with the offer, along with the inspection options available at load port.