Oxidized Bitumen, also known as Blown Bitumen, is a thermally and chemically modified bitumen produced by passing controlled air through hot penetration-grade bitumen (typically 230–260°C). During this process, oxidation reactions increase molecular weight and form complex asphaltene structures.
This controlled oxidation results in a higher softening point, lower penetration, increased viscosity, and superior thermal and chemical stability. Oxidized Bitumen is primarily used in non-paving, industrial, and waterproofing applications.
Oxidation (Blowing) Manufacturing Process
Base Bitumen Selection
High-quality penetration grade bitumen such as 60/70 or 80/100 is selected as feedstock.
Heating Stage
Bitumen is heated to 230–260°C in a blowing still.
Air Injection (Blowing)
Dry air is injected at controlled rates, forming ketones, carboxylic acids, and high-molecular-weight asphaltenes.
Property Control
Blowing time and temperature control softening point, penetration, viscosity, and elasticity.
Cooling & Filtration
Finished bitumen is cooled, filtered, tested, and packed.
Grade Designation System
Grades are designated by Softening Point / Penetration, such as:
85/25 · 90/15 · 95/20 · 115/15 · 75/30
First number = Softening Point (°C)
Second number = Penetration (dmm at 25°C)
Key Technical Characteristics
High Softening Point
Retains structural integrity at elevated temperatures and prevents sagging or flow.
Low Penetration & High Hardness
Provides dimensional stability and resistance to creep and deformation.
Excellent Water Resistance
Hydrophobic nature provides long-term waterproofing performance.
Chemical & Oxidative Stability
Resistant to mild acids, alkalis, and salts with slower aging.
Strong Adhesion
Excellent bonding with concrete, metal, brick, and asphalt membranes.
Thermoplastic Behavior
Softens on heating and hardens on cooling without chemical curing.
Durable & Non-Brittle
Maintains flexibility under temperature cycling with long service life.
Typical Mechanical & Physical Properties
| Property | Typical Range |
|---|---|
| Softening Point (R&B) | 70°C – 150°C |
| Penetration @ 25°C | 5 – 30 dmm |
| Ductility | Low (grade dependent) |
| Density @ 25°C | 1.00 – 1.05 g/cm³ |
| Flash Point | 250°C – 300°C |
| Loss on Heating | <1% |
| Solubility | ≥99% |
Comparison with Penetration & VG Bitumen
| Property | Oxidized Bitumen | Penetration / VG |
|---|---|---|
| Softening Point | Very High | Moderate |
| Penetration | Very Low | Medium to High |
| Elasticity | Lower | Higher |
| Temperature Stability | Excellent | Limited |
| Road Use | Not Recommended | Primary Application |
Available Supply Forms & Packaging
Solid blocks (25 / 35 kg)
Meltable poly bags (clean handling)
Steel drums (185 / 200 kg)
Bulk liquid supply for large consumers
Custom packaging as per project needs
Storage & Handling Guidelines
Store in cool, dry, covered areas
Avoid prolonged sunlight exposure
Maximum heating temperature: 200–230°C
Use indirect heating systems
Applications of Oxidized (Blown) Bitumen
Waterproofing & Roofing
Torch-on membranes, roofing felts, shingles, parapets, basement damp proofing
Construction & Civil Engineering
Expansion joint fillers, bridge bearing pads, crack sealing, protective coatings
Industrial Applications
Cable coating, bituminous paints, anti-corrosion coatings, adhesives, mastics
Chemical & Process Industries
Chemical tank linings, pipeline coatings, acid-resistant linings
Advantages of Oxidized Bitumen
Superior heat resistance
Excellent waterproofing performance
Long service life
Strong multi-surface adhesion
Low maintenance in harsh environments
Standards & Compliance
ASTM D312
ASTM D36 / D5
EN 13304
IS 702