The development of high performance polymer modified binders for asphalt use with improved fuming characteristics

Polymer modified binders (PMBs) have been used in Australia for some time to provide deformation and fatigue resistance in asphalt. The excellent performance of these binders has been recognised through increasing usage and through the publication of AUSTROADS and other specifications. Problems have, however, been encountered in the application of these materials, especially with SBS-based PMBs, with respect to the evolution of fumes during laying of the asphalt. This paper discusses the development by BP Australia of PMBs which exhibit reduced fuming characteristics and which have a low tendency for polymer segregation during hot storage. Binder properties are evaluated with conventional and more sophisticated testing, such as rheometry. A simple fuming test was devised to guide binder development. Dense graded asphalt mixes were characterised using SAA tests and AUSTROADS guidelines for mix design and stiffness, dynamic creep and fatigue, together with wheel tracking testing. Performance in open graded asphalt was indicated by conducting abrasion testing, binder drainage testing and other conventional asphalt testing. The encouraging laboratory performance indicators for binder fuming were confirmed by road trials carried out to monitor any adverse health effects experienced by crews on exposure to fumes. The excellent asphalt characteristics measured in the laboratory were also validated by conducting ALF testing to measure rutting at elevated temperatures.