A Study of the Low-Temperature Properties of Sulphur Extended Asphalt Mixtures

摘要

Sulphur Extended Asphalt (SEA) mixtures were used commercially in the 1970s and 1980s. Increases in sulphur prices, however, rendered SEA mixes uneconomical. Handling and safety issues also were of concern, as molten sulphur was difficult to use and occasionally generated hydrogen sulphide (H2S). Interest in the use of SEA mixes has been renewed by the precipitous rise in bitumen prices and some recent innovations in sulphur technology. A sulphur mixture modifier is supplied in pellet form, allowing easy handling and storage. The modified sulphur pellets are at ambient temperature when added to the Hot Mix Asphalt (HMA) during the mixing process. By keeping the mix temperature to a range of 130°- 145°C, H2S emissions are virtually eliminated. Although economic factors offer valid reasons to use SEA, recent laboratory studies have also shown that the addition of sulphur improves performance. Significantly enhanced performance in high temperature conditions has been well documented [2]. This study examines low temperature effects of SEA by using the Thermal Strength Restrained Specimen Test and also examines the effects of sulphur binder content as measured by stiffness modulus in both high and low temperatures. The study concludes that SEA can enhance the performance of HMA in both high and low temperature conditions.