Distribution of sulfur compounds in Brazilian asphalt cements and its relationship to short-term and long-term aging processes

Abstract In this work, speciation analysis of sulfur compounds was carried out in asphalt cements submitted to short-term and long-term processes. The separation of sulfur classes was obtained after selective oxidation/reduction steps followed by adsorption liquid chromatography. Five asphalt cements were comparatively analyzed (virgin and aged) for total sulfur distribution, what permitted to establish a possible mechanism for sulfur transformation occurring in Brazilian asphalts. The decrease of thiophenes (17.7–47.5%) was accompanied by the increase in aliphatic sulfides (2.6–19.6%), as well as aromatic/saturated sulfur (5.9–34.9%) in its more oxidized state after RTFOT and RTFOT + PAV aging. A disruption of thiophenic rings and their subsequent conversion to saturated/aromatic sulfur compounds and cyclic/polycyclic aliphatic sulfides can be established as possible route. It showed that part of chemical changes is related to conversion of thiophenes mostly in asphaltenic fraction, since maltenes were found to be relative stable over the thiophenes distribution after aging.