Oxidized bitumen is blown from blowing hot air to pure bitumen at the final stage of the purification operation in this process, hot air with a temperature of 200 to 300 degrees Celsius is blown through a perforated tube into a compartment containing bitumen.
Oxidized bitumen is categorized based on softening points and penetration rate. For example, oxidized bitumen 85/40 is a type of bitumen whose softening point is 85±5 degrees Centigrade and its penetration rate is 40±5 (0.1mm). Oxidized bitumen is also expected to make up for weight loss under heat. The softening point in oxidized bitumen is much higher than in regular bitumen, causing lower thermal sensitivity.