Oxidized Asphalt 75/35, also known as Blown Asphalt 75/35 or Oxidized Bitumen 75/35, is a semi-solid industrial grade bitumen produced by the controlled air-blowing (oxidation) of petroleum bitumen. This process significantly modifies the physical and chemical structure of the base bitumen, resulting in a material with a higher softening point, lower penetration, and improved thermal and mechanical stability compared to conventional penetration grade bitumen.

Definition and Material Characteristics

Oxidized Asphalt 75/35 is manufactured by passing very hot air through penetration grade bitumen, typically Bitumen 60/70, under carefully controlled conditions. The oxidation process increases the asphaltene content and reduces temperature susceptibility, producing a bitumen grade with enhanced durability and resistance to deformation.

The designation 75/35 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, Oxidized Asphalt 75/35 behaves predominantly as a solid material, while when heated and applied, it provides superior adhesion, sealing, and waterproofing performance.

Physical and Performance Properties

Oxidized Asphalt 75/35 is characterized by:

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

• High flash point, providing improved safety during heating and application

• Excellent thermal stability during repeated heating and cooling cycles

• Strong adhesive properties when applied hot

• High resistance to moisture penetration and environmental exposure

These properties make this grade particularly suitable for industrial and construction applications requiring long-term performance and reliability.

Meaning of Grade 75/35

The grade number 75/35 indicates:

• A softening point centered around 75°C, reflecting high thermal resistance

• A penetration value around 35 (0.1 mm), indicating a relatively hard and stable consistency

This combination places Oxidized Asphalt 75/35 between flexible paving bitumen and highly rigid industrial grades, making it suitable for applications where dimensional stability and waterproofing are critical.

Applications of Oxidized Asphalt 75/35

Oxidized Asphalt 75/35 is widely used in a broad range 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 projects

• Pipe coating for corrosion resistance

• Hydraulic applications and Portland cement pavement joints

• Paint, lacquer, and varnish manufacturing

• Asphalt-based coatings for metal corrosion protection

• 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 excellent waterproofing, dustproofing, corrosion resistance, and noise reduction.

Application Guidelines

Oxidized Asphalt 75/35 should be heated to approximately twice its softening point to achieve suitable flow and viscosity for application. All surfaces must be dry, clean, and free from dust, loose particles, curing compounds, slurry, and other contaminants prior to application to ensure proper adhesion and performance.

Storage, Handling, and Safety

When stored and handled in accordance with the product MSDS, Oxidized Asphalt 75/35 maintains its quality and performance for up to 10 years, even under multiple heating and cooling cycles. Proper storage conditions and temperature control are essential to preserve material integrity and safety.

Packaging and Supply

Oxidized Asphalt 75/35 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 from penetration grade bitumen through a controlled air-blowing process and supplied in full compliance with ASTM standards, ensuring consistent quality and specification conformity.

Technical Specification – Oxidized Asphalt 75/35

Conclusion

Oxidized Asphalt 75/35 is a versatile and high-performance blown bitumen designed for demanding industrial and construction applications. Its combination of elevated softening point, controlled hardness, excellent adhesion, and waterproofing capability makes it an ideal material for roofing, insulation, corrosion protection, and heavy-duty infrastructure projects where durability and thermal stability are essential.