Blown Bitumen 85/40, also known as Oxidized Bitumen 85/40, is a semi-solid industrial grade bitumen produced through the controlled air-blowing (oxidation) of petroleum bitumen. This manufacturing process alters the molecular structure of the base bitumen, increasing its softening point and improving thermal stability, durability, and resistance to deformation compared to conventional penetration grade bitumen.

Definition and Material Characteristics

Blown Bitumen 85/40 is manufactured by passing very hot air through penetration grade bitumen, typically Bitumen 60/70, under strictly controlled conditions. The oxidation process increases asphaltene content and reduces temperature susceptibility, resulting in a harder and more stable material suitable for demanding industrial and construction applications.

The designation 85/40 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 Bitumen 85/40 behaves predominantly as a solid material, while when heated and applied, it offers excellent adhesion, sealing capability, and waterproofing performance.

Physical and Performance Properties

Blown Bitumen 85/40 is characterized by:

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

• High flash point, ensuring safer handling during heating and application

• Good stability during repeated heating and cooling cycles

• Strong adhesive and cohesive properties

• Effective resistance to moisture penetration and environmental exposure

These characteristics make this grade suitable for applications requiring controlled hardness and long-term performance.

Meaning of Grade 85/40

The grade number 85/40 indicates:

• A softening point centered around 85°C, reflecting enhanced thermal resistance

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

This balance places Blown Bitumen 85/40 between flexible paving grades and very hard industrial grades, making it ideal for waterproofing, insulation, and protective applications.

Applications of Blown Bitumen 85/40

Blown Bitumen 85/40 is widely used in a variety of industrial and construction applications, including:

• Roofing and waterproofing systems

• Bitumen membrane sheets for insulation and isolation

• Road construction, pavement works, and crack sealing

• Civil engineering and public works structures

• Pipe coating for corrosion resistance

• Asphalt-based paints for metal protection

• Paint, lacquer, and varnish manufacturing

• Adhesives and electrical laminate bonding

• Synthetic turf base layers

• Caulking, mastics, and damp proofing systems

In addition, this grade is extensively used in the automotive industry for vehicle undercoating, where it provides waterproofing, dustproofing, corrosion resistance, and noise reduction.

Application Guidelines

Blown Bitumen 85/40 should be heated to approximately twice its softening point to achieve suitable flow and viscosity. All surfaces must be dry, clean, and free from dust, loose particles, curing compounds, slurry, and other contaminants to ensure proper adhesion and performance.

Storage, Handling, and Safety

When stored and handled in accordance with the product MSDS, Blown Bitumen 85/40 maintains its quality and performance for up to 10 years, even under multiple heating and cooling cycles. Proper temperature control and safe handling practices are essential to preserve material integrity.

Packaging and Supply

Blown Bitumen 85/40 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 and supplied in full compliance with ASTM standards, ensuring consistent quality and specification conformity.

Technical Specification – Blown Bitumen 85/40

Conclusion

Blown Bitumen 85/40 is a reliable and versatile oxidized bitumen grade designed for waterproofing, insulation, corrosion protection, and industrial construction applications. Its elevated softening point, controlled penetration, and strong adhesive properties make it an excellent choice for projects requiring durability, thermal stability, and long-term performance.