Bitumen
Bitumen Density Explained: Why kg/m³ Values Vary
The single most common source of estimating error in bitumen calculations is using the wrong density value — here is how to pick the right one.
Ask three different suppliers for the density of bitumen and you may get three slightly different numbers — not because anyone is wrong, but because density is not a single fixed constant. It depends on grade, temperature, and the reference standard being used.
The typical range
At 15°C, penetration-grade bitumen (60/70, 80/100, etc.) typically falls between 1000 and 1050 kg/m³ (roughly 62–65 lb/ft³), with 1030 kg/m³ being a commonly used working average when a supplier-specific value is not yet available. Bitumen emulsions are lighter, generally 1000–1020 kg/m³, since a portion of their volume is water. Modified bitumens (polymer-modified, SBS-modified) can sit slightly outside this range depending on the modifier percentage.
| Material | Typical Density Range | Notes |
|---|---|---|
| Penetration-grade bitumen (60/70, 80/100) | 1000–1050 kg/m³ | Reference temperature 15°C unless stated otherwise |
| Bitumen emulsion | 1000–1020 kg/m³ | Lower due to water content (typically 30–40% water) |
| Cutback bitumen | 990–1020 kg/m³ | Varies with solvent/diluent ratio |
| Polymer-modified bitumen (PMB) | 1010–1060 kg/m³ | Depends on polymer type and dosage |
Why temperature changes the number
Bitumen expands as it heats, so its density drops as temperature rises — roughly 0.6–0.7 kg/m³ per °C for most grades, though this varies slightly by supplier data sheet. That means bitumen weighed hot at 150°C occupies noticeably more volume per tonne than the same bitumen at 15°C. If you are converting between weight and volume, always confirm which temperature the density figure applies to — mixing a 15°C reference density with a volume measured at 150°C will overstate your material requirement.
Approximate temperature correction
Density at T°C ≈ Density at 15°C − [0.0006 × (T − 15)]
Use this only as a rough estimate. For contractual quantities, use the correction factor table from ASTM D1250 or your supplier’s technical data sheet.
Which value should you actually use?
For estimating and quoting: use your specific supplier’s data sheet value if you have one, or 1030 kg/m³ as a reasonable working default for penetration-grade bitumen. For contractual, invoiced, or as-built quantities: always use the certified value from the delivery docket, since payment is often based on weighbridge tickets, not calculated volume.
Density vs specific gravity — don’t confuse the two
Bitumen specifications sometimes quote "specific gravity" (a unitless ratio relative to water) instead of density (kg/m³ or lb/ft³). Numerically, specific gravity and density in g/cm³ are close (SG of 1.03 ≈ 1030 kg/m³), but make sure you are not accidentally plugging a specific gravity number directly into a calculator field that expects kg/m³ — the values look deceptively similar but off by three decimal places.
Enter your supplier’s density value directly into the calculator for accurate results