Selecting Warm Mix Asphalt (WMA) additives by the properties of WMA binders

The objective of this research was to investigate the influence of WMA additives on the properties of WMA binders through a series of laboratory testing such as viscosity, penetration, ductility, and softening points on the binders. The experimental design included the use of three WMA additives of Sasobit, Rediset, and Evotherm at a recommended content of 2, 2 and 0.6% respectively, two base binder sources, and one modified binder sources. The properties of WMA binders were compared to those of original asphalts without the additives as controls. Results from this study showed that: (1) Three WMA additives of Sasobit, Evotherm and Rediset increased the dynamic viscosity (60 °C) of asphalt binders; (2) The additives of Evotherm and Rediset reduced the kinematic viscosity (130 °C) of tested WMA asphalt binders. Adding 2 % Sasobit did not affect the kinematic viscosity; (3) Adding 2 % Sasobit reduced the penetration of WMA asphalt binder obviously. The most reduced rate of penetration is 22.7 % for SK base asphalt binder; (4) The WMA additives increased the softening point of WMA asphalt binders, except for the case with 0.6 % Evotherm. The effect of adding 2% Sasobit on the softening point of asphalt binders is the most significant, while the effect of adding 0.6 % Evotherm is the least; (5) adding 0.6 % Evotherm increased the ductility of warm asphalt binders by 28.6 %, while adding 2 % Sasobit reduced the ductility of warm asphalt binders obviously