Impact of Water during the Laboratory Aging of Asphalt

ABSTRACT A series of asphalts was PAV aged at 60 and 80°C in the absence or presence of water for varying lengths of time. The chemical and rheological properties of these aged asphalts are compared. It was concluded that water and temperature increase the extent of chemical aging by apparently disrupting the colloidal structure of asphalt. The consequence being that additional reactive compounds are available to undergo oxidation at the relatively mild conditions employed during the laboratory aging procedure. It appears that the stiffness of sol-type asphalts is less affected by increasing amounts of polar compounds than gel-type asphalts. The compatibility of the asphalts was also affected by aging, generally decreasing with increasing time of aging. The exception was AAM-1 (SHRP designation), a sol-type asphalt whose compatibility increased with increasing time of aging. It was also demonstrated that the extent of oxidative aging is asphalt-source dependent.