Laboratory · Bitumen and asphalt mixtures
A road surface lasts only as long as its binder and its mix allow. We test bitumen grades and asphalt mixtures, from the job mix formula in the laboratory to samples taken behind the paver, so that a pavement is built to the specification it was designed for.
All eight tests are accredited under ISO/IEC 17025 (DPA certificate LT 069), with asphalt sampling to BS EN 12697-27.
When you need these tests
- Designing and approving the job mix formula for a new asphalt plant or project.
- Daily production control at the asphalt plant.
- Acceptance of laid layers for roads, car parks and airfields.
- Checking bitumen deliveries against the declared penetration grade.
Accredited tests and standards
Bitumen binders
| Test | What it tells you | Range | Standard | Where |
|---|---|---|---|---|
| Needle penetration | Hardness of the binder; classifies the penetration grade | 5–330 dmm | BS EN 1426:2015; BS 2000-49:2015 | Laboratory |
| Softening point (ring and ball) | Temperature at which bitumen softens; classifies the grade | 0.1–130 °C | BS EN 1427:2015; BS 2000-58:2015; ASTM D36/D36M-14(2020) | Laboratory |
Asphalt mixtures
| Test | What it tells you | Range | Standard | Where |
|---|---|---|---|---|
| Binder content by extraction | Checks the binder content against the approved job mix | 3.0–6.0% | BS EN 12697-1:2020; ASTM D2172/D2172M-17e1 Sampling: BS EN 12697-27:2017 |
Laboratory |
| Particle size distribution of recovered aggregate | Grading of the aggregate recovered from the mix | 0.063–50 mm | BS EN 12697-2:2015+A1:2019 Sampling: BS EN 12697-27:2017 |
Laboratory |
| Bulk density (Marshall specimens) | Compaction reference for the mix and the laid layer | 2.0–2.7 g/cm³ | BS EN 12697-6:2020 Sampling: BS EN 12697-27:2017 |
Laboratory |
| Air voids content | Too many voids means low durability; too few means rutting | 0.1–9.0% | ASTM D3203-22; BS EN 12697-8:2018 Sampling: BS EN 12697-27:2017 |
Laboratory |
| Marshall stability and flow | Load-bearing performance of the mix | 0.1–50 kN; 0.05–10 mm | BS EN 12697-34:2020; ASTM D6927-22 Sampling: BS EN 12697-27:2017 |
Laboratory |
| Asphalt concrete mix design (job mix formula) | Designs the production recipe to meet the project specification | — | BS EN 13108-1:2016; BS EN 13108-4:2016; BS EN 13108-20:2016 Sampling: BS EN 12697-27:2017 |
Laboratory |
Sampling and what to send us
- Loose asphalt: about 10–15 kg per sample, taken to BS EN 12697-27, in sealed metal containers.
- Bitumen: about 1 kg in a clean, sealed tin, with the delivery reference.
- For mix design: representative aggregate fractions, filler and the binder you intend to use.
What your test report contains
- A unique report number, the accredited laboratory’s details and the ISO/IEC 17025 accreditation mark for accredited tests.
- Sample identification, sampling details and the condition of the sample on receipt.
- The standard and method used for every test, with any deviation stated.
- Results with units, and comparison with the specified limits when you give them to us.
- Signature of the authorised laboratory staff.
Frequently asked questions
What does a Marshall test tell me?
Stability and flow describe how the mix carries load; together with density and air voids they show whether the mix meets the design and will resist rutting and cracking.
Can you design an asphalt mix?
Yes. Job mix formulas to BS EN 13108-1, -4 and -20 are within our accredited scope.
Related testing
Tell us the material, the quantity of samples and the specification you are working to. We’ll confirm the tests, the sampling and the price.