You want to know how rejuvenators, also called Recycling Agents, can modify old asphalt binders? This note explains why bitumen ages and how to rejuvenate it with the right product.
Bitumen aging
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.
Figure 1: Considered the first modern photograph, the heliograph "Point de vue du Gras" was taken by J. N. Niépce probably in 1827 using Judea bitumen. It made use of the propensity of bitumen to age upon light exposure. It is conserved at the Harry Ransom Center of the University of Austin (Texas, USA). Full reference of original picture is: Joseph Nicéphore Niépce (French, 1765–1833), Untitled 'point de vue,' 1827. Heliograph on pewter, 16.7 x 20.3 x .15 cm. Gernsheim Collection, purchase, 964:0000:0001. Picture courtesy of HRC: https://www.hrc.utexas.edu/niepce-heliograph/
RoadMat, "Can an old aged bitumen become like new again? Or why use rejuvenators...", RoadMat Note 5, 2020, published Feb 24, 2020 - last modified Dec 1, 2023
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