Blown Bitumen 75/25 or Oxidized Bitumen or Blown Asphalt is produced by blowing hot air into the penetration bitumen. This action makes the bitumen more rubbery than its original formula and it becomes harder bitumen. This bitumen recovers the weight loss under heating. Due to low thermal sensitivity, the softening point is much higher than regular bitumen and the penetration index (PI) is higher than road construction bitumen (8>PI>2) due to the letter having a gel-like structure because of asphalt accumulation.
Blown Bitumen 75/25 is produced by the air-blowing of penetration grade bitumen. This is done at high temperatures, resulting in a material of a much higher penetration index. RAHA Bitumen 75/25 is based on petroleum bitumen which is made by blowing bitumen 60/70 by very hot air. The designation of the Blown Bitumen 75/25 refers to the midpoint of the softening point acceptance criteria.
