Bitumen Content Test(ASTM D2172 — Centrifuge Extraction)
Determination of binder content in bituminous mixes by centrifuge extraction per ASTM D2172 — verifying the as-produced binder percentage against the Job Mix Formula within the ±0.3% tolerance required by MoRTH Section 500.
What is the Bitumen Content Test?
Binder content is the single most cost- and performance-critical parameter of a bituminous mix. Too little bitumen and the layer ravels and fatigues early; too much and it ruts and bleeds. MoRTH Specifications (Fifth Revision), Section 500, therefore fixes the binder content in the approved Job Mix Formula and allows a production tolerance of only ±0.3% by mass of total mix — verified by routine extraction testing at prescribed frequencies.
Global Lab determines bitumen content by centrifuge extraction per ASTM D2172 — the mix sample is washed with solvent in a centrifuge extractor until the effluent runs clear, and the binder content is computed from the mass difference after accounting for filler carried into the extract. The recovered aggregate from the same operation feeds directly into the gradation test, giving JMF verification for both parameters from a single sample.
How the Bitumen Content Test is Conducted
- 1
Sampling & Weighing
A representative production sample is taken at MoRTH-prescribed frequency, split to test size, and its initial mass recorded accurately. - 2
Centrifuge Extraction
The sample is placed in the ASTM D2172 centrifuge extractor bowl with solvent; repeated wash-and-spin cycles continue until the effluent runs clear of binder. - 3
Filler Correction
Fine mineral matter carried into the extract is determined (by ashing or centrifuging an aliquot) and credited back to the aggregate mass, as the method requires. - 4
Drying & Final Weighing
The extracted aggregate is dried to constant mass; the binder content is calculated from the mass difference, expressed as percent of total mix. - 5
JMF Comparison
The measured binder content is compared with the approved Job Mix Formula value and the ±0.3% MoRTH tolerance, with a clear pass/fail verdict. - 6
Reporting
The certificate — binder content, JMF reference and verdict — is issued via Autovity QLMS.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| ASTM D2172/D2172M | Standard Test Methods for Quantitative Extraction of Asphalt Binder from Asphalt Mixtures | Centrifuge Extraction | ASTM Standard |
| ASTM D6307 | Standard Test Method for Asphalt Content of Asphalt Mixture by Ignition Method | Alternative Ignition Method | ASTM Standard |
| MoRTH (5th Rev.) Sec. 500 | Specifications for Road and Bridge Works — Bituminous Courses | Binder Content Tolerance (±0.3%) | MoRTH Spec |
| IRC:111-2009 | Specifications for Dense Graded Bituminous Mixes | DBM / BC Binder Requirements | IRC Code |