Low Temperature Performance of Sasobit-Modified Warm-Mix Asphalt

In the summer of 2008, a field trial project using Sasobit-modified warm-mix asphalt (WMA) was established in Alaska, which was Alaska’s first experience with a WMA technology. Previous studies conducted by writers identified a number of engineering benefits of Sasobit-modified WMAs over conventional hot-mix asphalt (HMA). This paper presents a further assessment focusing on low temperature performance of both Sasobit-modified WMA binders and mixes. A series of binder tests including bending beam rheometer (BBR), direct tension test (DTT), and asphalt binder cracking device (ABCD) tests were conducted. Indirect tension tests (IDT) of mixtures along with a thermal cracking analysis were performed to obtain a more definitive answer regarding the WMA application for cold-weather conditions. Results showed a decrease of tensile strength for both WMA binders and mixtures at low temperatures, and the cracking temperatures of both WMA binders and mixtures increased with the increase of Sasobit content. However, the increase in cracking temperature was very slight, which indicated that Sasobit addition had an insignificant effect on resistance to low temperature cracking. Therefore, Sasobit-modified WMA should be suitable for the Northern Region of the Alaska Department of Transportation and Public Facilities (AKDOT&PF) without compromising the resistance to low temperature cracking.