Abstract
The basic concept of warm mix asphalt (WMA) technologies is to reduce the asphalt binder viscosity, which allows the asphalt to attain a suitable viscosity to coat the aggregates and thus to compact asphalt mixtures at lower temperatures. A main concern for adding WMA additives to asphalt is that it might reduce the rutting resistance at high temperatures and the cracking resistance at low temperatures. To address these concerns, this article presents the impacts of various amounts of WMA additives on the viscosity and low-temperature cracking of asphalt binder. The test results at 135°C show that the viscosity of asphalt reduced significantly when 0.5 % of Additive B was added; the viscosity did not decrease when up to 1.0 % of Additive A was added. When the temperature was lowered to 120°C, however, a more drastic reduction in viscosity was observed when just 0.5 % of additives were added, and the viscosity remained relatively steady as the dosage was increased up to 3.0 %. These viscosity test results confirm that the higher amounts of WMA additives do not necessarily reduce the viscosity of asphalt binder. To characterize the low temperature property of the asphalt binder, the asphalt binder with WMA additives were tested using the asphalt binder cracking device (ABCD). As the WMA additives were increased from 0.5 % to 3.0 %, the cracking temperature increased slightly but remained steady near the cracking temperature of the virgin asphalt binder. The ABCD test results confirm that the cracking temperature of asphalt binder is not significantly affected by WMA additives.
