A review of Sulfur Extended Asphalt Modifiers: feasibility and limitations

Sulfur Extended Asphalt Modifier (SEAM) is currently being marketed as an additive for hot asphalt mix-tures. Typically 40% by mass of the binder phase in the asphalt mix can be replaced by SEAM using conven-tional mix design and production techniques. A number of full scale trials using SEAM have been reported in the literature and, except for some minor concerns regarding rutting and moisture resistance, it appears that overall the SEAM modified mixes have the potential for improved mechanical performance compared to conventional asphalt. During the production stages of SEAM asphalt mixes in conventional hot mix plants, the sulfur component will exist in the liquid phase, which requires careful thermal management to control gaseous emissions. As a consequence, this paper includes a general review of exposure limits for sul-fur dioxide and hydrogen sulfide emissions and their short and long term health effects on healthy and asth-matic individuals.