Sulphur-extended asphalt:: reaction kinetics of H2S evolution

The interest in sulphur-asphalt mixtures was especially high in the 1970s and 1980s. At present, there is concern about the behaviour of sulphur-extended asphalts (SEA) because of the problems that could arise during the recycling of old SEA pavements. This paper studies the kinetics of H2S evolution during the reaction of sulphur with asphalt; such a reaction starts well below 150 degrees C, as previously stated. The activation energy and the reaction order are different for various types of material: for cracked bitumens the reaction order is 0.5, while for straight run products it is higher and dependent on the type of bitumen. The results of the study suggest operating with great caution when heating SEA mixtures. (C) 1998 Elsevier Science Ltd. All rights reserved.