Evaluation of Warm Mix Asphalt for Alaska Conditions

Abstract

In line with a field demonstration project of WMA using Sasobit conducted in Southeast Alaska, this study focused on experimentally assessing the engineering properties of Sasobit modified WMA binders and mixes. Performance tests of binders were conducted according to Superpave specification to assess the correlation between the content of additives, and Superpave performance grade (PG) and stiffness of modified binders. Tests conducted to assess the performance of WMA included 1) permanent deformation (rutting) susceptibility, 2) low temperature cracking performance including tensile strength and tensile creep compliance properties, 3) moisture susceptibility, and 4) dynamic modulus |E*|. Laboratory investigation of Sasobit-modified binders and WMAs in this study identified a lot of engineering benefits of WMAs using Sasobit over traditional HMA. WMAs using Sasobit with reduced mixing and compaction temperatures, improved workability and rutting resistance, and insignificant effect on moisture susceptibility favorably indicated the suitability of this WMA technology for Alaska conditions. The indirect tension test (IDT) results showed degraded resistance to low temperature cracking of WMA using Sasobit in this study. However, additional tests at lower temperatures, along with a more complete thermal cracking analysis for specific environments of interest should be performed to get a more definitive answer regarding the effects of Sasobit on low temperature cracking.