An Alternative Asphalt Binder, Sulfur-Extended Asphalt (SEA)

Background In the early 1970s, due to concern over asphalt cement supply issues and an anticipated over abundance of elemental sulfur, many organizations Société Nationale des Pétroles d’Aquitaine (SNPA), Gulf Oil of Canada, Sulfur Development Institute of Canada (SUDIC), Texas Chemical Company, U.S. Bureau of Mines, and the Texas Transportation Institute) began to evaluate the potential for sulfur to substitute for asphalt as a binder extender; this became known as SulfurExtended Asphalt (SEA). At the time, it was projected that there would be an abundant amount of sulfur from many sources: pyrite processing into sulfuric acid, natural gas recovery, crude oil refining, coal usage, other chemical processes, and desulfurization from smoke stack emissions. Sixty-eight test sections were constructed between 1975 and 1984; 18 of these were monitored under FHWA Demonstration Project No. 54 (DP54). This was initiated in 1979 and provided design, construction, and evaluation assistance (1). The Demonstration Projects Division organized a task force, with the Sulfur Institute to conduct a comparative performance review of the SEA pavements with that of conventional asphalt concrete (AC) pavement control sections. Twenty-six projects in 18 states were evaluated.