Laboratory Evaluation of Warm-Mix Open Graded Friction Course Mixtures

Abstract

The objective of this study was to evaluate the feasibility of using warm mix asphalt (WMA) technologies to produce quality open graded friction course (OGFC) mixtures. This evaluation was based on the comparison of Evotherm WMA and foamed WMA mixes with traditional hot mix asphalt (HMA) OGFC using three primary criteria: draindown, permeability, and abrasion resistance. The results of the study indicated that fibers could be removed from OGFC mixtures when using the WMA technologies included in this study. This conclusion was based on the performance evaluation of the mixtures, which showed that when the fibers were removed, the permeability of the mix almost doubled. Additionally, the WMA mixtures without fibers met typical aged abrasion loss requirements and the foamed WMA mixtures without fibers performed similarly with regard to aged abrasion resistance to the HMA mixture with fibers, whereas the HMA mix without fibers showed lower resistance to abrasion than the WMA mixtures. The enhanced performance of the mixtures can be attributed to the increased binder film thickness of the WMA mixtures compared to the HMA mixtures without fibers.