Midrange Temperature Rheological Properties of Warm Asphalt Binders

Abstract

With increasing concerns of global warming and increasing emissions, the asphalt industry is making a constant effort to lower its emissions by reducing the mixing and compaction temperatures of the asphalt mixture without affecting the properties of the mix. Several proprietary chemicals are available in the industry that can help reduce the mixing and compaction temperatures. A significant reduction of required heat can be achieved in most cases. Several studies have been conducted evaluating the properties of the warm mix asphalt; however, properties of the binders containing these chemicals have not been studied in great detail. Warm asphalts were produced using two of the available processes utilizing five different asphalt binder sources, and some rheological tests were conducted (dynamic shear rheometer and viscosity). The results indicated that binders containing the inorganic additive Aspha-Min (Eurovia, France) underwent minor or no changes compared to the base binders in terms of flow properties, stiffness, and response to creep. However, the flow of binders with the additive Sasobit (Sasol Wax, Germany), which consists of aliphatic hydrocarbons, changed from Newtonian to shear thinning at 60°C, and the viscosity of the binder at 60°C increased. Sasobit also improved the stiffness and penetration resistance of the base binders, and binders with Sasobit had significantly lower permanent deformations after repeated creep-recovery tests compared to the base binders.