Calculator
Example Data
| Case | Wm (g) | Wmoist (g) | Wa (g) | Wf (g) | Wcorr (g) | Bitumen % (dry) |
|---|---|---|---|---|---|---|
| A | 1200 | 0 | 1120 | 10 | 0 | 5.83% |
| B | 1500 | 15 | 1390 | 12 | 3 | 5.40% |
| C | 1000 | 0 | 945 | 8 | 0 | 4.70% |
These examples assume recovered fines are measured separately and included as mineral matter.
Formula Used
This calculator estimates binder mass by subtracting recovered mineral matter from the dry sample mass.
- Dry mix mass:
Wd = Wm − Wmoist - Total mineral matter:
Wmin = Wa + Wf + Wcorr - Bitumen mass:
Wb = Wd − Wmin - Bitumen content (% dry mix):
Pb(dry) = (Wb / Wd) × 100 - Bitumen content (% as received):
Pb(wet) = (Wb / Wm) × 100 - Bitumen content (% of mineral matter):
Pb(agg) = (Wb / Wmin) × 100
Notes: Use consistent units (grams). Set optional fields to 0 when not applicable.
How to Use This Calculator
- Weigh the asphalt mix sample before extraction and enter Wm.
- If the sample includes moisture, enter Wmoist; otherwise use 0.
- After extraction and drying, weigh recovered aggregate and enter Wa.
- If you recover fines separately, enter Wf; else keep 0.
- Apply any required correction as Wcorr when specified by your method.
- Optionally set binder limits to check compliance, then press Submit.
- Use Download CSV or Download PDF to archive results.
Technical Notes and Practical Guidance
1) Why bitumen content matters in asphalt work
Bitumen content directly affects durability, rut resistance, and moisture susceptibility. Too little binder can leave aggregates uncoated, increasing raveling and early cracking. Too much binder can reduce stability, increase bleeding, and trap voids. Routine extraction testing helps confirm that production matches the job mix formula and supports consistent field performance.
2) Input data and typical laboratory ranges
The calculator uses mass balance from extraction test measurements. For many mixes, a lab sample may be between 800 g and 2000 g, with moisture mass often near 0 g for properly conditioned samples. Recovered aggregate mass should be close to the dry mix mass, while fines mass may range from 0 g to 20 g depending on gradation and recovery method. Keep units consistent in grams.
3) Moisture, fines, and correction terms
Moisture reduces the effective dry mix mass, so the calculator computes Wd = Wm − Wmoist. If fines are recovered separately, they should be counted as mineral matter (Wf) to avoid overstating binder. Some procedures also require mineral matter corrections (Wcorr) for dissolved material or systematic losses. Use the values specified by your method and equipment.
4) Reading the outputs for reporting
The primary compliance value is binder percentage by dry mix mass, Pb(dry). The calculator also reports binder as a percentage of the as‑received sample and as a percentage of mineral matter to support internal reviews. When you enter specification limits, the PASS/CHECK label is evaluated against Pb(dry) to match common quality control practice.
5) Quality checks to improve repeatability
Verify that balances are calibrated and that aggregate is oven‑dried to constant mass before recording Wa. Record filter and pan tare masses to reduce transcription errors. If the calculated bitumen mass becomes negative, the mineral matter total is exceeding the dry sample mass; recheck moisture, fines recovery, and correction entries. Exporting the CSV or PDF helps maintain an auditable trail for each test.
FAQs
1) Which bitumen percentage should I report to the client?
Most specifications use binder content as % by dry mix mass. Use Pb(dry) unless your project documents require a different basis.
2) When should I enter moisture mass (Wmoist)?
Enter Wmoist when the sample is not fully dry at the time you record Wm. If the sample is conditioned and dry, keep Wmoist as 0.
3) What is the fines mass (Wf) field for?
Use Wf if your procedure recovers fine material separately from the aggregate. Including fines in mineral matter avoids inflating binder content.
4) What does mineral matter correction (Wcorr) represent?
Some methods apply a correction for dissolved mineral matter or systematic losses. Enter the correction required by your standard operating procedure; otherwise leave it as 0.
5) Why do I see a negative bitumen mass?
A negative value means total mineral matter exceeds the dry sample mass. Recheck Wa, Wf, Wcorr, and moisture entries, and confirm drying and tare procedures.
6) Can I use kilograms instead of grams?
Yes, if all inputs use the same unit. The percentages are unit‑independent, but the report labels assume grams, so keep documentation consistent.
7) Does the PASS/CHECK compare against Pb(wet) or Pb(dry)?
PASS/CHECK is based on Pb(dry), which aligns with typical asphalt binder content specifications. If your spec differs, interpret the outputs accordingly.