Editing Bitumen (section)

=== Additives, mixtures and contaminants ===
For economic and other reasons, bitumen is sometimes sold combined with other materials, often without being labeled as anything other than simply "bitumen".<ref name="whats_in_your_asphalt_2017_09_fhwa">Arnold, Terence S. (senior research chemist, Pavement Materials Team, Office of Infrastructure Research and Development, [[Federal Highway Administration]]; Federal lab manager for the chemistry lab, [[Turner-Fairbank Highway Research Center]]; fellow of the [[Royal Society of Chemistry]] in the United Kingdom), [https://highways.dot.gov/public-roads/september-2017/whats-your-asphalt "What's in Your Asphalt?,"] September 2017 (last modified 25 October 2017), ''Public Roads'', FHWA-HRT-17-006.htm," Office of Research, Development, and Technology, Office of Corporate Research, Technology, and Innovation Management, [[Federal Highway Administration]], [[U.S. Department of Transportation]]</ref>

Of particular note is the use of [[Automotive oil recycling#REOB|re-refined engine oil bottoms – "REOB" or "REOBs"]]{{snd}}the residue of [[Automotive oil recycling|recycled automotive engine oil]] collected from the bottoms of re-refining [[vacuum distillation]] towers, in the manufacture of asphalt. REOB contains various elements and compounds found in recycled engine oil: additives to the original oil and materials accumulating from its circulation in the engine (typically iron and copper). Some research has indicated a correlation between this adulteration of bitumen and poorer-performing pavement.<ref name="whats_in_your_asphalt_2017_09_fhwa" />