The Filler Bitumen Ratio Calculator helps civil engineers, road construction contractors, and material technologists find the right balance between mineral filler and bitumen in asphalt mixes. This ratio plays a major role in deciding the stiffness, durability, and workability of hot mix asphalt. A well-balanced ratio ensures the road surface stays smooth, resists cracking, and withstands heavy traffic loads. This calculator belongs to the Pavement Mix Design and Material Quality Calculator category and is commonly used in quality control, mix design labs, and field projects.
formula of Filler Bitumen Ratio Calculator
Filler-Bitumen Ratio = Weight of Mineral Filler / Weight of Bitumen
Where:
Weight of Mineral Filler is the fine material like stone dust, lime, or cement added to fill voids and improve bonding (in kg or grams)
Weight of Bitumen is the total weight of the binder used in the mix (same unit as filler)
Expressed as:
Filler-Bitumen Ratio = F / B
Example:
If Filler (F) = 60 kg
Bitumen (B) = 300 kg
Then:
Filler-Bitumen Ratio = 60 / 300 = 0.20
Importance:
In practice, target ratios for hot mix asphalt range from 0.8 to 1.2 by weight to get good coating, workability, and resistance to deformation. Adjusting this ratio helps meet pavement performance standards.
Common Filler-Bitumen Ratios Reference Table
This table shows typical filler-bitumen ratio ranges for different mix types and conditions.
| Asphalt Mix Type | Recommended Filler-Bitumen Ratio (by weight) |
|---|---|
| Dense Bituminous Macadam (DBM) | 0.8–1.0 |
| Bituminous Concrete (BC) | 1.0–1.2 |
| Stone Mastic Asphalt (SMA) | 1.2–1.5 |
| Cold Mix Asphalt | 0.7–0.9 |
This helps designers pick suitable values without recalculating for each project.
Example of Filler Bitumen Ratio Calculator
Let’s solve a practical example.
You have an asphalt batch where:
Filler = 50 kg
Bitumen = 60 kg
- Use the formula:
Filler-Bitumen Ratio = F / B = 50 / 60 = 0.83
So, the filler-bitumen ratio is 0.83. This fits within the normal range for Dense Bituminous Macadam, ensuring good stability and bonding.
Most Common FAQs
This ratio controls the stiffness and durability of asphalt. Too much filler makes the mix brittle; too little causes poor bonding and rutting under traffic.
Not all fillers are the same. Common choices include stone dust, hydrated lime, and cement. They must meet standard grading and chemical requirements to avoid negative reactions.
If the ratio is too low, add more filler or slightly reduce bitumen content. However, always test new mix samples in the lab to confirm stability and performance.