Abstract
This study evaluated the resistance of field-produced warm-mix asphalt (WMA) mixtures obtained from field sections in Manitoba, Canada, to moisture damage, reflective cracking, and permanent deformation. The project, constructed in the summer of 2010, included a side-by-side hot-mix asphalt (HMA) control section and three WMA sections in which the Advera, Evotherm 3G, and Sasobit technologies were used. The mixtures' susceptibility to moisture damage was evaluated by their unconditioned and moisture-conditioned indirect tensile strength (ITS) and dynamic modulus (|E*|) at multiple freeze–thaw cycles. All mixtures met the minimum unconditioned ITS criterion of 65 psi at 77°F and the minimum indirect tensile strength ratio of 80% after one freeze–thaw cycle. Although comparable tensile strength and |E*| ratios were observed for the mixtures after one freeze–thaw cycle, the WMA–Sasobit mixture exhibited lower resistance to moisture damage when assessed after three freeze–thaw cycles. Except for the WMA–Sasobit mixture, the WMA mixtures showed similar or higher resistance to reflective cracking when measured by means of the Texas A&M Transportation Institute overlay tester. All WMA mixtures exhibited similar resistance to permanent deformation in the flow number test at the LTPPBind 50% reliability temperature (118°F) as compared with the HMA control section. However, none of the mixtures (including the HMA) met the proposed flow number criterion for WMA. When the mixtures were tested in the flow number test at the effective pavement temperature (92°F), a different ranking for their resistance to rutting was detected. Continuous field monitoring for performance of the various sections will help in assessing any proposed criterion as well as the effectiveness of WMA mixtures in cold weather areas such as Manitoba.