Laboratory Evaluation of Sasobit-Modified Warm-Mix Asphalt for Alaskan Conditions

Abstract

A number of completed or ongoing studies on different aspects of warm-mix asphalt (WMA) have being conducted in the United States, indicating pavement professionals’ strong interest in exploring the application of this innovative technology. In the summer of 2008, a field trial project using Sasobit-modified WMA was established in the southeastern region of Alaska, which was Alaska’s first experience with a WMA technology. In line with this field experimental feature project, this paper presents a systematic laboratory study of both Sasobit-modified WMA binders and mixes. Engineering properties of Sasobit-modified WMA binders and mixes were experimentally evaluated, and the effects of Sasobit addition on the WMA’s performance in terms of low temperature behavior, rutting resistance, and moisture susceptibility were investigated. Research results identified a number of engineering benefits of Sasobit-modified WMAs over conventional HMA. Sasobit-modified WMAs reduced mixing and compaction temperatures, improved workability and rutting resistance, and had insignificant effect on moisture susceptibility. These effects indicated the suitability of this WMA technology for central and southeastern regions of the Alaska Department of Transportation and Public Facilities (AKDOT&PF). The indirect tension test results showed a decrease of WMAs tensile strength at low temperatures. Additional tests at lower temperatures, along with a more complete thermal cracking analysis need to be performed to obtain a more definitive answer regarding the low temperature performance of these mixes for the northern region of AKDOT&PF.