Bitumen has been known to be prone to chemical aging from the very beginning of its modern use in road construction.

As a matter of fact, Joseph Nicéphore Niépce made some of the very first recorded photographs in the early 1820s by exposing a solution of Dead Sea or Judea bitumen to light (see Figure 1 below). This procedure created insoluble compounds that could not be washed away and remained as part of the picture [1].

Also, it was widely known at the turn of the 20th Century that a combination of high temperature and exposure to air flow could harden a soft bitumen base. This evolved into the modern air-blowing process which was already widespread in 1920.

In parallel, the age-hardening of bitumen upon outdoor exposure was noticed by the road industry at the very beginning of asphalt paving. It had raised sufficient attention for researchers to set-up accelerated aging methods as early as 1897.