Blown Asphalt 90/40, also known as Oxidized Bitumen 90/40 or Blown Bitumen 90/40, is a semi-solid industrial grade bitumen produced through the controlled air-blowing (oxidation) of petroleum bitumen. This oxidation process modifies the molecular structure of the base bitumen, increasing the softening point while maintaining a controlled penetration range, resulting in improved thermal stability, durability, and resistance to deformation compared to conventional penetration grade bitumen.

Definition and Material Characteristics

Blown Asphalt 90/40 is manufactured by passing very hot air through penetration grade bitumen, typically Bitumen 60/70, under carefully controlled conditions. During oxidation, the bitumen undergoes polymerization reactions that increase asphaltene content and reduce temperature susceptibility, producing a stable material suitable for industrial and construction applications.

The designation 90/40 represents the midpoint values of the product’s key physical properties:

• Softening Point, measured in degrees Celsius using the Ring and Ball method in accordance with ASTM D36

• Penetration, measured in tenths of a millimeter (0.1 mm) at 25°C in accordance with ASTM D5 or IP49

At ambient temperatures, Blown Asphalt 90/40 behaves as a solid or semi-solid black material, gradually becoming fluid when heated.

Physical and Performance Properties

Blown Asphalt 90/40 is characterized by:

• High softening point, providing excellent resistance to flow at elevated temperatures

• Controlled penetration, offering a balance between hardness and workability

• High flash point, ensuring safer heating and application

• Good ductility compared to harder oxidized grades

• Stability during repeated heating and cooling cycles

• Strong adhesive, sealing, and waterproofing properties

These characteristics make this grade suitable for both industrial and construction-related applications.

Meaning of Grade 90/40

The grade 90/40 indicates:

• A softening point centered around 90°C, reflecting high thermal resistance

• A penetration value around 40 (0.1 mm), indicating a semi-hard consistency

This combination positions Blown Asphalt 90/40 as a versatile oxidized bitumen grade, offering greater flexibility than very hard grades such as 90/10 or 90/15, while maintaining excellent heat resistance.

Applications of Blown Asphalt 90/40

Blown Asphalt 90/40 is widely used in a broad range of industrial and construction applications, including:

• Roofing felts and waterproofing systems

• Bitumen membrane sheets for insulation and isolation

• Pipe coating for corrosion resistance

• Anti-rust and anti-slip compounds

• Sound dampening felts and vibration control materials

• Joint filling compounds and sealants

• Bituminous mastics and industrial coatings

It is also extensively used in:

• Road construction, pavement works, and crack sealing

• Civil engineering and public works structures

• Asphalt-based paints for metal corrosion protection

• Paint, lacquer, and varnish manufacturing

• Adhesives and electrical laminate bonding

• Synthetic turf base layers

• Caulking, mastics, and damp proofing systems

In addition, Blown Asphalt 90/40 is widely applied in the automotive industry for vehicle undercoating, where it provides excellent waterproofing, dustproofing, corrosion resistance, and noise reduction.

Application Guidelines

Blown Asphalt 90/40 should be heated to approximately twice its softening point to achieve proper flow and workable viscosity. Prior to application, all surfaces must be dry, clean, and free from dust, loose particles, curing compounds, slurry, oil, or other contaminants to ensure effective adhesion and long-term performance.

Storage, Handling, and Safety

When stored and handled in accordance with the product MSDS, Blown Asphalt 90/40 maintains its quality and performance for up to 10 years, even under multiple heating and cooling cycles. Proper storage conditions and controlled reheating are essential for safety and material integrity.

Packaging and Supply

Blown Asphalt 90/40 is available in various packaging options to meet different customer and project requirements, including:

• Kraft paper bags

• Meltable plastic bags

• Steel drums

• Bulk supply

The product is manufactured through a controlled air-blowing process from penetration grade bitumen and supplied in full compliance with ASTM standards, ensuring consistent quality and specification conformity.

Technical Specification – Blown Asphalt 90/40

Conclusion

Blown Asphalt 90/40 is a versatile and high-performance oxidized bitumen designed for waterproofing, insulation, corrosion protection, and industrial construction applications. Its combination of high softening point, controlled penetration, good ductility, and excellent stability makes it an ideal choice for projects requiring durability, thermal resistance, and reliable long-term performance.